JP7556736B2 - Apparatus, molding system, method, and computer program for acquiring deviation amount from proper position of mold - Google Patents

Description

This disclosure relates to an apparatus, molding system, method, and computer program for acquiring the amount of deviation from the correct position of a mold.

A molding system is known that acquires the amount of deviation from the correct position of a mold installed in a molding machine (for example, Patent Document 1).

JP 2018-89850 A

There has been a demand for technology that can more easily obtain the amount of deviation from the correct position of a mold in a molding machine.

In one aspect of the present disclosure, the mold has a first surface that is arranged to extend in the direction of a first axis perpendicular to the central axis of the mold when the mold is placed in a predetermined appropriate position relative to the molding machine. The device for acquiring the amount of deviation from the appropriate position of the mold installed in the molding machine includes a first distance acquisition unit that acquires a first distance in the direction of the central axis and a second axis perpendicular to the first axis between a first reference point and a second reference point that are determined on the first surface at positions spaced apart from each other in the direction of the first axis when the installation position of the mold is displaced from the appropriate position, and a deviation amount acquisition unit that acquires a first amount of deviation around the central axis of the mold from the appropriate position using the first distance acquired by the first distance acquisition unit.

In another aspect of the present disclosure, a method for acquiring an amount of deviation from an appropriate position of a mold installed in a molding machine includes a processor acquiring a first distance in the direction of a central axis and a second axis perpendicular to the first axis between a first reference point and a second reference point defined on a first surface at positions spaced apart from each other in the direction of the first axis when the installation position of the mold is displaced from the appropriate position, and acquiring a first amount of deviation around the central axis of the mold from the appropriate position using the first distance acquired by the first distance acquisition unit.

According to the present disclosure, the amount of work required to obtain the amount of deviation can be reduced, making it easier and faster to obtain the amount of deviation.

FIG. 1 illustrates a molding system according to one embodiment. FIG. 2 is a block diagram of the molding system shown in FIG. 1 . FIG. 2 is an enlarged view of the end effector shown in FIG. 1 . The mold is shown in the correct position. This shows a state in which the mold installation position has been displaced from the appropriate position. 3 is a flowchart showing an example of a flow for acquiring reference data indicating a proper position of a mold in the molding system shown in FIG. 2 . This shows the state at the end of step S1 in FIG. This shows the state when the determination in step S4 in FIG. 6 is YES. 3 is a flowchart showing an example of a flow for acquiring an amount of deviation of a mold from a proper position in the molding system shown in FIG. 2 . This shows the state when the determination in step S4 in FIG. 9 is YES. 10 is a flowchart showing another example of the flow for acquiring the amount of deviation of the mold from the appropriate position in the molding system shown in FIG. 2 . FIG. 11 is a block diagram of a molding system according to another embodiment. 11 shows the state at the end of step S11 in FIG. 11 in the molding system shown in FIG. 3 is a block diagram showing other functions of the molding system shown in FIG. 2. This shows a state in which the mold installation position has been displaced from the appropriate position. 15 is a flowchart showing an example of a flow for acquiring an amount of deviation of a mold from a proper position in the molding system shown in FIG. 14 . 17 is a flowchart showing an example of the flow of steps S21, S22, and S25 in FIG. 16. This shows the state at the end of step S31 in step S25. This shows the state when the determination in step S25 is YES in step S34. 10 is a flowchart showing another example of the flow for acquiring the amount of deviation of the mold from the appropriate position in the molding system shown in FIG. 2 . 21 is a flowchart showing an example of the flow of steps S21' and S22' in FIG. 20. 3 is a diagram for explaining a method for acquiring the amount of deviation of the mold in the direction of the central axis from the correct position in the molding system shown in FIG. 2. FIG. 13 is a block diagram showing further functions of the molding system shown in FIGS. 2 and 12 . 24 is a diagram for explaining a method for acquiring the amount of deviation of the mold in the direction of the central axis relative to the correct position in the molding system shown in FIG. 23. 24 is a flowchart showing an example of an operation flow of the molding system shown in FIG. 23.

Below, an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that in the various embodiments described below, similar elements will be given the same reference numerals, and duplicated explanations will be omitted. In addition, in the following description, the robot coordinate system C1 in the drawings will be used as the reference for directions, and for convenience, the positive direction of the x-axis of the robot coordinate system C1 will be referred to as the right, the positive direction of the y-axis as the forward direction, and the positive direction of the z-axis as the upward direction.

First, referring to Figures 1 and 2, a molding system 10 according to one embodiment will be described. The molding system 10 includes a molding machine 12, a robot 14, a control device 16, and a sensor 17 (Figure 2). The molding machine 12 is, for example, an injection molding machine or a die-cast molding machine, and has a mold installation section 18 and a mold 20 that is detachably installed in the mold installation section 18.

In this embodiment, the mold 20 is a substantially rectangular prism-shaped member having a central axis A1, and has a left side 22, a right side 24, a bottom side 26, a top side 28, and a rear side 30. Each of the left side 22, the right side 24, the bottom side 26, the top side 28, and the rear side 30 is substantially flat. The left side 22 and the right side 24 are arranged parallel to each other and facing each other.

The lower surface 26 and the upper surface 28 are arranged parallel to each other and perpendicular to the left surface 22 and the right surface 24. The rear surface 30 is perpendicular to the central axis A1 and perpendicular to the left surface 22, the right surface 24, the lower surface 26, and the upper surface 28. A cavity 32 is formed in the center of the mold 20. A material such as resin is poured into this cavity 32, and the molding machine 12 produces a molded product by molding the material in the cavity 32.

The robot 14 performs a predetermined operation (e.g., removing the molded product or inserting an insert part into the molded product) on the molded product molded by the molding machine 12 using the mold 20. In this embodiment, the robot 14 is a vertical articulated robot and has a robot base 34, a rotating body 36, a robot arm 38, a wrist 40, and an end effector 42. The robot base 34 is fixed on the floor of the work cell. The rotating body 36 is mounted on the robot base 34 so that it can rotate around a vertical axis.

The robot arm 38 has a lower arm 44 that is rotatably attached to the rotating body 36 around a horizontal axis, and an upper arm 46 that is rotatably attached to the tip of the lower arm 44. The wrist 40 is rotatably attached to the tip of the upper arm 46, and rotates the end effector 42 around the wrist axis A2.

The end effector 42 is detachably attached to the tip of the wrist 40 (so-called wrist flange). In this embodiment, the end effector 42 is a robot hand capable of gripping an object. As one example, the end effector 42 has an adsorption part (negative pressure generator, electromagnet, suction cup, etc.) that adsorbs an object, and grips the object by adsorbing it with the adsorption surface. As another example, the end effector 42 has multiple claws that can be opened and closed, and grips the object by pinching it with the claws.

Each component of the robot 14 (robot base 34, rotating body 36, lower arm 44, upper arm 46, wrist 40) has a built-in servo motor 48 (Figure 2). These servo motors 48 rotate each movable element of the robot 14 (rotating body 36, lower arm 44, upper arm 46, wrist 40) around a drive axis in response to commands from the control device 16. As a result, the robot 14 can move the end effector 42 forward and backward into the mold 20 and perform a specified operation on the molded product formed by the mold 20.

The sensor 17 detects the contact force CF as a detection value α when the robot 14 touches up the mold 20 with the end effector 42. As an example, the sensor 17 has a six-axis force sensor 17A provided on the robot base 34, the rotating body 36, the robot arm 38, or the wrist 40. The six-axis force sensor 17A has multiple strain gauges and detects the magnitude and direction of the external force applied to the end effector 42.

When the robot 14 touches up the mold 20 with the end effector 42 with a contact force CF, an external force corresponding to the contact force CF is applied from the mold 20 to the end effector 42 as a reaction force to the contact force. The six-axis force sensor 17A can detect the contact force CF as an external force applied to the end effector 42. The detection value α of the six-axis force sensor 17A includes the magnitude of the external force applied to the end effector 42 or the output value of the strain gauge.

As another example, the sensor 17 is built into the robot 14 and has a feedback sensor 17B that detects a feedback value FB (feedback current, load torque, etc.) from the servo motor 48. Specifically, when the robot 14 touches up the mold 20 with a contact force CF, an external force is applied from the mold 20 to the end effector 42 as described above.

The feedback value FB from the servo motor 48 varies in response to this external force. Therefore, the feedback sensor 17B can detect the magnitude of the contact force CF from the feedback value FB. In this case, the detection value α of the feedback sensor 17B is the feedback value FB.

As yet another example, the sensor 17 has a torque sensor 17C provided on each servo motor 48 of the robot 14. The torque sensor 17C detects the torque applied to the drive shaft of the servo motor 48. When the robot 14 touches up the mold 20, the external force applied from the mold 20 to the end effector 42 is applied as a torque to the drive shaft of each servo motor 48.

The torque sensor 17C can therefore detect the magnitude of the contact force CF from the torque. In this case, the detection value α of the torque sensor 17C includes the value of the torque applied to the drive shaft, or the value of the external force applied to the end effector 42, which is calculated from the torque detected by each torque sensor 17C.

As shown in FIG. 2, the control device 16 is a computer having a processor 50, a memory 52, and an I/O interface 54, and controls the molding machine 12, the robot 14, and the sensor 17. The processor 50 is communicatively connected to the memory 52 and the I/O interface 54 via a bus 56, and performs calculations to realize various functions described below while communicating with the memory 52 and the I/O interface 54.

The memory 52 has a RAM or a ROM, etc., and temporarily or permanently stores various data. The I/O interface 54 has, for example, an Ethernet (registered trademark) port, a USB port, an optical fiber connector, or an HDMI (registered trademark) terminal, and communicates data with an external device via a wired or wireless connection under instructions from the processor 50. The servo motor 48 and the sensor 17 described above are connected to the I/O interface 54 so as to be able to communicate via a wired or wireless connection.

As shown in FIG. 1, a robot coordinate system C1 is set for the robot 14. The robot coordinate system C1 is a coordinate system for automatically controlling the operation of each movable element of the robot 14, and is fixedly set with respect to the robot base 34. In this embodiment, the robot coordinate system C1 is set with respect to the robot 14 so that its origin is located at the center of the robot base 34 and its z axis coincides with the rotation axis of the rotating body 36 (i.e., the vertical direction).

On the other hand, as shown in FIG. 3, a tool coordinate system C2 is set for the end effector 42. This tool coordinate system C2 is a coordinate system that defines the position of the end effector 42 in the robot coordinate system C1. In this embodiment, the tool coordinate system C2 is set for the end effector 42 so that its origin is located at a known working point 42a of the end effector 42 and its z axis is parallel to the wrist axis A2.

When moving the end effector 42, the processor 50 sets a tool coordinate system C2 in the robot coordinate system C1, and generates a command to each servo motor 48 of the robot 14 to position the end effector 42 at a position represented by the set tool coordinate system C2. In this way, the processor 50 positions the end effector 42 at an arbitrary position in the robot coordinate system C1. The origin position (i.e., the working point 42a) of the tool coordinate system C2 in the robot coordinate system C1 and the direction of each axis are known. Note that in this document, "position" may refer to position and orientation.

The processor 50 operates the robot 14 according to a previously created operation program OP0, and causes the robot 14 to perform the above-mentioned predetermined operations (such as removing a molded product or inserting and removing an insert part into a molded product) on a molded product molded by the molding machine 12 using the mold 20. For example, the operation program OP0 can be created by teaching the actual robot 14 the operations to perform operations on a molding machine 12 whose mold 20 is installed in a predetermined appropriate position relative to the mold installation section 18 (Figure 1) in real space.

Alternatively, the operation program OP0 may be created by placing a model of the molding machine 12 and a model of the robot 14 in a virtual space and performing a simulation to operate these models in the virtual space (so-called offline teaching). The model of the molding machine 12 and the model of the robot 14 are 3D CAD models having ideal dimensions (i.e., design dimensions), and therefore, in the model of the molding machine 12, the model of the mold 20 is placed in a predetermined appropriate position. The created operation program OP0 is stored in advance in the memory 52.

Here, the operator may change the mold 20 (so-called stage change) depending on the manufacturing process. In this case, the installation position of the mold 20 relative to the mold installation section 18 may be displaced from the appropriate position. An example of such a displacement of the mold 20 will be described below with reference to Figures 4 and 5. Figure 4 shows a state in which the mold 20 is placed in a predetermined appropriate position relative to the mold installation section 18 (Figure 1).

Here, in this embodiment, when the mold 20 is installed in the appropriate position, the central axis A1 of the mold 20 is approximately parallel to the y axis of the robot coordinate system C1, the left surface 22 and the right surface 24 of the mold 20 are arranged so as to extend in the direction of the z axis (first axis) of the robot coordinate system C1 (or are arranged so as to be perpendicular to the x axis of the robot coordinate system C1), and the lower surface 26 and the upper surface 28 of the mold 20 are arranged so as to extend in the direction of the x axis (second axis) of the robot coordinate system C1 (or are arranged so as to be perpendicular to the z axis of the robot coordinate system C1). Also, the coordinates of the central axis A1 of the mold 20 in the x-z plane of the robot coordinate system C1 at this time are ( _xA , _zA ). In other words, the central axis A1 is expressed as a known coordinate _QA ( _xA , y, _zA ) of the robot coordinate system C1.

On the other hand, FIG. 5 shows a state in which the installation position of the mold 20 has been displaced from the appropriate position. In the example shown in FIG. 5, the mold 20 has been displaced from the appropriate position shown by the dotted line so as to rotate around the central axis A1 by a deviation amount θ (first deviation amount). In this embodiment, the processor 50 functions as a device 60 (FIG. 2) that acquires the deviation amount θ of the mold 20 from the appropriate position.

The function of the device 60 will be described below with reference to FIG. 6. The flow shown in FIG. 6 is executed using an actual molding machine 12 in which the mold 20 is placed in the appropriate position as shown in FIG. 4. The processor 50 starts the flow shown in FIG. 6 when it receives a reference data acquisition command from an operator, a higher-level controller, or a computer program.

In step S1, the processor 50 places the robot 14 at a predetermined initial position IP. This initial position IP is determined in advance by the operator, for example, as a position where the working point 42a of the end effector 42 is spaced downward from the central axis A1 of the mold 20 by a distance Δ1 and spaced leftward from the left surface 22 of the mold 20.

For example, the initial position IP can be determined as a coordinate in the robot coordinate system C1 that sets the origin of the tool coordinate system C2. The operator can set the distance Δ1 arbitrarily within the range of 0<Δ1< _Δ1MAX . This upper limit value _Δ1MAX is the distance in the z-axis direction of the robot coordinate system C1 from the central axis A1 to the lower surface 26. A state in which the robot 14 is placed at the initial position IP is shown in FIG. The z-coordinate of the working point 42a in the robot coordinate system C1 at this time is z= _zA -Δ1.

In step S2, the processor 50 starts acquiring the detection value α. Specifically, the processor 50 sends a command to the sensor 17, and the sensor 17 acquires the detection value α continuously (e.g., periodically) in response to the command. The processor 50 sequentially acquires the detection value α from the sensor 17 via the I/O interface 54 and stores it in the memory 52.

In step S3, the processor 50 operates the robot 14. Specifically, the processor 50 operates each movable element of the robot 14 to move the end effector 42 to the right from the initial position IP shown in FIG. 7. As a result, the working point 42a approaches the left surface 22 of the mold 20.

In step S4, the processor 50 determines whether the most recently acquired detection value α has become a predetermined reference value α ₀ (>0). For example, the processor 50 may determine YES when the most recently acquired detection value α is within an allowable range [α _th1 , α _th2 ] that is determined to include the reference value α ₀ (i.e., α _th1 ≦α≦α _th2 ).

The thresholds α _th1 and α _th2 that define the allowable range [α _th1 , α _th2 ] can be predetermined by an operator as values that satisfy, for example, 0 < α _th1 < α ₀ < α _th2 . If the processor 50 determines YES, it stops the operation of the robot 14 and proceeds to step S5, whereas if the processor 50 determines NO, it returns to step S3.

If the determination in step S4 is NO, the processor 50 may determine the direction in which to move the end effector 42 in step S3 to be executed subsequently as a direction that can bring the detection value α closer to the reference value α _0. For example, if the determination in step S3 is NO because the detection value α is greater than the reference value α ₀ (or the threshold value α _th2 ), the direction in which to move the end effector 42 in step S3 to be executed subsequently may be determined to be to the left.

In this manner, the processor 50 repeats the loop of steps S3 and S4 until a YES determination is made in step S4. When a YES determination is made in step S4, the working point 42a comes into contact with the left surface 22 at a reference point P1 with a contact force _CF0 corresponding to a reference value _α0 , as shown in FIG.

In step S5, the processor 50 acquires position data RP1 of the robot 14. Specifically, the processor 50 acquires, as the position data RP1 of the robot 14, coordinates _Q1 (x1, y1, z1) in the robot coordinate system C1 of the origin (i.e., the working point 42a) of the tool coordinate system C2 at this point in time (i.e., the point in time _{when YES} is determined in step _S4 ).

In this embodiment, since the origin of the tool coordinate system C2 is set at the working point 42a, the coordinate _Q1 ( _x1 , _y1 , _z1 ) indicates the coordinate of the reference point P1 on the left surface 22 with which the working point 42a comes into contact. Therefore, _z1 = _zA - Δ1. The coordinate _x1 of this coordinate _Q1 becomes the reference data indicating the position of the left surface 22 placed in the appropriate position in the x-axis direction of the robot coordinate system C1.

After executing the flow of FIG. 6, when the installation position of the mold 20 is displaced as shown in FIG. 5 due to a change in the mold 20 or the like, the processor 50 executes the flow shown in FIG. 9. In the flow shown in FIG. 9, the same processes as those in the flow shown in FIG. 6 are given the same step numbers, and duplicated explanations are omitted. The processor 50 starts the flow shown in FIG. 9 when it receives a deviation acquisition command from an operator, a higher-level controller, or a computer program.

After the flow shown in Fig. 9 starts, the processor 50 executes steps S1 to S5 in the same manner as in the flow of Fig. 6. The positional relationship between the robot 14 and the mold 20 at the time when YES is determined in step S4 is shown in Fig. 10. At this time, the working point 42a of the robot 14 comes into contact with the first reference point P2 on the left surface 22 with a contact force CF ₀ at the position of coordinates (y ₁ , z ₁ ) in the yz plane of the robot coordinate system C1.

Then, in step S5, the processor 50 acquires coordinates _Q2 ( _x2 , y2, _z2 ) in the robot coordinate system C1 of the origin of the tool coordinate system C2 (i.e., working point 42a) as position data RP2 of the robot 14 at this time. Here, since _y2 = _y1 , _z2 = _z1 = _zA - _Δ1 , coordinates _Q2 ( _x2 , _y2 , _z2 ) are expressed as ( _x2 , _y1 , _zA - Δ1). In this embodiment, coordinates _Q2 indicate the coordinates of the first reference point P2 in the robot coordinate system C1.

5 shows the base point P1 and the first reference point P2. In this embodiment, a second reference point P3 is set on the intersection between the left surface 22 placed in the appropriate position indicated by a dotted line and the left surface 22 after being displaced from the installation position. The coordinates of this second reference point P3 in the robot coordinate system C1 are, for example, ( _x1 , _y1 , _zα ). In this way, the first reference point P2 and the second reference point P3 are points set on the left surface 22 at positions spaced apart from each other in the z-axis direction of the robot coordinate system C1.

In step S6, the processor 50 acquires the distance between the first reference point P2 and the second reference point P3. Specifically, the processor 50 acquires the distance δ1 (first distance) between the first reference point P2 and the second reference point P3 in the x-axis direction of the robot coordinate system C1. Here, as shown in FIG. 5, the distance δ1 between the first reference point P2 and the second reference point P3 in the x-axis direction (i.e., the distance between the first reference point P2 and the base point P1 in the x-axis direction) can be calculated as δ1=x ₁ -x ₂ from the coordinate x ₁ of the position data RP1 (coordinate Q ₁ ) acquired in step S5 of FIG. 6 and the coordinate x ₂ of the position data RP2 (coordinate Q ₂ ) acquired in step S5 of FIG. 9. In this way, in this embodiment, the processor 50 functions as the first distance acquisition unit 62 (FIG. 1) that acquires the distance δ1 (first distance).

In step S7, the processor 50 obtains the deviation θ using the distance δ1. As shown in Fig. 5, if the distance in the z-axis direction of the robot coordinate system C1 between the second reference point P3 and the central axis A1 is Δ2, the deviation θ is expressed as a known formula (trigonometric function) as θ = tan ^-1 (δ1/(Δ1 + Δ2)).

As described above, Δ1 is known. Furthermore, when the deviation θ is an extremely small angle, Δ2 can be approximated to zero (Δ2≈0). Thus, the processor 50 can use the distance δ1 to obtain the deviation θ as an approximate value from the formula θ=tan ^-1 (δ1/Δ1). Thus, in this embodiment, the processor 50 functions as the deviation acquisition unit 64 that acquires the deviation θ using the distance δ1.

As described above, in this embodiment, the processor 50 functions as the device 60 including the first distance acquisition unit 62 and the deviation amount acquisition unit 64. This device 60 can acquire the distance δ1 at one position (coordinate z=z _A −Δ1) in the z-axis direction of the robot coordinate system C1 defined by the operator, and acquire the deviation amount θ from the distance δ1 determined at that one position. This can reduce the number of steps required to acquire the deviation amount θ, making it possible to acquire the deviation amount θ more simply and quickly.

In addition, in this embodiment, the distance δ1 is obtained based on the detection value α detected by the sensor 17 when the robot 14 touches up the base point P1 and the first reference point P2 (steps S4 to S6). With this configuration, the process of obtaining the distance δ1 can be effectively automated, and the flow shown in FIG. 9 can be realized with a relatively simple algorithm.

In this embodiment, the processor 50 obtains the distance δ1 based on the position data RP2 of the robot 14 when the detection value α detected by the sensor 17 becomes a predetermined reference value α ₀ when the robot 14 touches up the reference point P1 and the first reference point P2. According to this configuration, the distance δ1 is obtained using the position data RP2 when the same reference value α ₀ is detected at the reference point P1 and the first reference point P2, so that the distance δ1 can be calculated more accurately.

Next, other functions of the molding system 10 will be described with reference to FIG. 11. In the flow shown in FIG. 11, the same processes as those in the flow of FIG. 9 are given the same step numbers, and duplicated descriptions will be omitted. After the installation position of the mold 20 is displaced as shown in FIG. 5, the processor 50 starts the flow shown in FIG. 11 when it receives a deviation acquisition command from an operator, a higher-level controller, or a computer program.

In step S11, the processor 50 moves the robot 14 to a reference position PR1. Here, the reference position PR1 of the robot 14 is determined in advance by an operator with the mold 20 arranged at the appropriate position as a reference. The operator may determine the reference position PR1 by teaching the robot 14 using the actual mold 20 arranged at the appropriate position, or may determine the reference position PR1 through the above-mentioned offline teaching. Below, a case will be described in which the operator sets the reference position PR1 to the coordinate _Q1 ( _x1 , _y1 , _z1 ) of the reference point P1. The memory 52 stores the coordinate _Q1 ( _x1 , _y1 , _z1 ) in advance in the memory as the position data of the reference position PR1.

In step S11, the processor 50 first places the robot 14 at the initial position IP, then sets the origin of the tool coordinate system C2 to the reference position PR1: coordinate _Q1 ( _x1 , _y1 , _z1 ), operates the robot 14, and moves the end effector 42 (working point 42a) rightward from the initial position IP toward the coordinate _Q1 ( _x1 , _y1 , _z1 ). As a result, as in Fig. 10, the working point 42a comes into contact with the first reference point P2 on the left surface 22, and the movement of the end effector 42 is stopped.

The processor 50 may execute this step S11 according to a pre-created operation program OP1. This operation program OP1 may be created by teaching the robot 14 the operation of step S11 using an actual mold 20 placed in an appropriate position, or it may be created through the offline teaching described above.

In step S12, the processor 50 acquires from the sensor 17 the detection value _α1 detected by the sensor 17 when the movement of the end effector 42 stops in step S11, and stores the detection value α1 in the memory 52. This detection value _α1 corresponds to the contact force _CF1 between the working point 42a and the first reference point P2 when the movement of the end effector 42 stops in step S11.

In step S13, the processor 50 functions as the first distance acquisition unit 62 and acquires the distance δ1 (first distance) in the x-axis direction of the robot coordinate system C1 between the first reference point P2 and the second reference point P3. As an example, the memory 52 stores in advance a data table DT1 indicating the relationship between the detection value α and the distance δ1. This data table DT1 can be created by collecting data on the detection value α and the distance δ1 in advance through an experiment or simulation. An example of the data table DT1 is shown in Table 1 below.

As shown in Table 1, in the data table DT1, the detection value α of the sensor 17 (specifically, the numerical range of the detection value α) and the distance δ1 are stored in association with each other. The processor 50 searches the data table DT1 for the distance δ1 corresponding to the detection value _α1 acquired in step S12. In this way, the processor 50 can acquire the distance δ1 using the data table DT1.

As another example, the memory 52 prestores a data table DT2 that indicates the relationship between the detection value α of the sensor 17 and the position of the first reference point P2 (specifically, the x-coordinate of the robot coordinate system C1). In this data table DT2, similar to the above-mentioned data table DT1, the detection value α of the sensor 17 (e.g., a numerical range) and the x-coordinate are stored in association with each other.

The processor 50 searches the data table DT2 to obtain the x coordinate: x _α1 corresponding to the detection value _α1 obtained in step S12. Next, the processor 50 obtains the distance δ1 as δ1 = x _α1 - x _1. In this manner, the processor 50 can obtain the distance δ1 using the data table DT2.

As yet another example, before executing the flow of Fig. 11 (i.e., before the installation position of the mold 20 is displaced), the processor 50 acquires in advance the detection value α1_R detected by the sensor 17 when the robot 14 is placed at the reference position PR1: coordinate _Q1 ( _x1 , _y1 , _z1 ) in the appropriate position shown in Fig. 4. Thereafter, the processor 50 calculates the difference _dα (= _{α1 -α1_R} ) between the detection value _α1 acquired in step S11 when executing the flow of Fig. ₁₁ and the detection value _{α1_R} acquired in advance.

On the other hand, the memory 52 prestores a data table DT3 indicating the relationship between the difference _dα and the distance δ1. In this data table DT3, the difference _dα (e.g., a numerical range) and the distance δ1 are stored in association with each other. This data table DT3 can also be regarded as a data table indicating the relationship between the detection value _α1 and the distance δ1.

The processor 50 searches the data table DT3 for the distance δ1 corresponding to the acquired difference _dα . In this way, the processor 50 can acquire the distance δ1 using the data table DT3. After acquiring the distance δ1, the processor 50 executes the above-mentioned step S7, functions as the deviation amount acquisition unit 64, and acquires the deviation amount θ using the acquired distance δ1.

As described above, in this embodiment, the processor 50 obtains the distance δ1 based on the detection value _α1 detected by the sensor 17 when the robot 14 is moved to the predetermined reference position PR. Here, the positioning accuracy for positioning the robot 14 at a predetermined position in the robot coordinate system C1 is relatively high. Therefore, when the flow of Fig. 11 is repeatedly executed every time the die 20 is changed, the reproducibility of the operation of step S11 is high, and the distance δ1 can be obtained with high accuracy from the detection value _α1 obtained as a result.

Next, a molding system 70 according to another embodiment will be described with reference to Figs. 1 and 12. The molding system 70 differs from the above-described molding system 10 in the sensor 72. The sensor 72 detects the distance β between the robot 14 and the mold 20 as a detection value β. For example, the sensor 72 has a displacement sensor or a distance measuring sensor provided at the working point 42a of the robot 14. The sensor 72 is connected to the I/O interface 54 in a wired or wireless manner so as to be able to communicate with the I/O interface 54, and transmits the detection value β to the control device 16.

Next, the function of the molding system 70 will be described with reference to FIG. 6. The processor 50 of the molding system 70 executes the flow of FIG. 6 for the mold 20 placed in the appropriate position, thereby acquiring reference data indicating the position of the left surface 22 in the appropriate position. Specifically, in step S1, the processor 50 places the robot 14 at the initial position IP. At this time, the sensor 72 is oriented so as to detect the distance β in the x-axis direction of the robot coordinate system C1 between the working point 42a and the left surface 22 facing the working point 42a.

In step S2, the processor 50 starts acquiring the detection value β. Specifically, the processor 50 sends a command to the sensor 72, and the sensor 72 acquires the detection value β continuously (e.g., periodically) in response to the command. The processor 50 sequentially acquires the detection value β from the sensor 72 via the I/O interface 54 and stores it in the memory 52.

After starting step S3, in step S4, the processor 50 determines whether the most recently acquired detection value β has become a predetermined reference value β ₀ (≧0). For example, the processor 50 may determine YES when the most recently acquired detection value β is within an allowable range [β _th1 , β _th2 ] that is determined to include the reference value β ₀ (i.e., β _th1 ≦α≦β _th2 ).

If the processor 50 determines that the result is YES, it stops the operation of the robot 14 and proceeds to step S5, whereas if the processor 50 determines that the result is NO, it returns to step S3. Note that if the processor 50 determines that the result is NO in step S4, it may determine that the direction in which the end effector 42 is to be moved in step S3 to be executed thereafter is the direction in which the detection value β can be brought closer to the reference value β ₀ .

If the reference value _β0 is set to _β0 = 0, and the determination in step S4 is YES, the working point 42a will come into contact with the left surface 22 at the reference point P1, as shown in Fig. 8. On the other hand, if the reference value _β0 is set to a value _β0 > 0, and the determination in step S4 is YES, the working point 42a will be located at a position spaced to the left of the reference point P1 by the reference value _β0 .

In step S5, the processor 50 acquires position data RP3 of the robot 14. Specifically, the processor 50 acquires, as the position data RP3 of the robot 14, coordinates _Q3 ( _x3 , _y3 , _z3 ) in the robot coordinate system C1 of the origin (working point 42a) of the tool coordinate system C2 at this time point.

In this embodiment, since _y3 = _y1 , _z3 = _z1 = zA _- Δ1, coordinate _Q3 ( _x3 , _y3 , _z3 ) is expressed as ( _x1 - _β0 , _y1 , _zA - Δ1). The coordinate _x3 of coordinate _Q3 becomes reference data indicating the position of the left surface 22, which is placed in the appropriate position, in the x-axis direction of the robot coordinate system C1. Since the reference value _β0 is known, the processor 50 may directly determine the coordinate _Q1 ( _x1 , _y1 , _z1 ) = ( _x1 , _y1 , _zA - Δ1) of reference point P1 by adding _β0 to the coordinate x3 of the position data RP3 in _{step S5} .

Thereafter, when the installation position of the mold 20 is displaced as shown in Fig. 5, the processor 50 of the molding system 70 executes the flow shown in Fig. 9. Specifically, the processor 50 executes steps S1 to S5 in the same manner as the flow shown in Fig. 6. If the reference value β ₀ is set to 0, when the determination in step S4 in Fig. 9 is YES, the working point 42a comes into contact with the left surface 22 at the first reference point P2: coordinate Q ₂ (x ₂ , y ₂ , z ₂ ), as shown in Fig. 10. On the other hand, if the reference value β ₀ is set to >0, when the determination in step S4 is YES, the working point 42a is located at a position spaced to the left of the first reference point P2 by the reference value β ₀ .

Then, in step S5, the processor 50 acquires coordinates _Q4 ( _x4 , _y4 , z4) in the robot coordinate system C1 of the origin (working point 42a) of the tool coordinate system C2 at this time as position data RP4 of the robot 14. This coordinate _Q4 ( _x4 , _y4 , _z4 ) is expressed as ( _x2 - _β0 , _{y2 , z2} ) = ( _x2 - _β0 , _y1 , _zA -Δ1). Since the reference value _β0 is known, in step S5, the processor 50 may directly determine the coordinate _Q2 ( _x2 , _y2 , _z2 ) = ( _x2 , _y1 , _zA -Δ1) of the first reference point P2 by adding _β0 to the coordinate _x4 of the position data RP4.

In step S6, the processor 50 functions as the first distance acquisition unit 62 and acquires the distance δ1 (first distance) in the x-axis direction of the robot coordinate system C1 between the first reference point P2 and the second reference point P3. Specifically, the processor 50 can calculate δ1=x3-x4 (= _x1 - _{x2 )} from the coordinate _x3 of the position data RP3 ( _coordinate Q3) acquired in step S5 of Fig. 6 and the coordinate _x4 of the position data RP4 (coordinate _Q4 ) acquired in step S5 of Fig. ₉ .

Furthermore, if the processor 50 directly determines the coordinate Q ₁ (x ₁ , y ₁ , z _A -Δ1) of the base point P1 in step S5 of Fig. 6, and directly determines the coordinate Q ₂ (x ₂ , y ₁ , z _A -Δ1) of the first reference point P2 in step S5 of Fig. 9, the distance δ1 can be determined as δ1 = x ₁ - x _2. Then, in step S7, the processor 50 functions as the deviation amount acquisition unit 64, and determines the deviation amount θ from the formula θ = tan ^-1 (δ1/Δ1), as in the above-mentioned embodiment.

According to this embodiment, as in the above-described embodiment, the number of steps required to obtain the deviation amount θ can be reduced, so that the deviation amount θ can be obtained more easily and quickly. In addition, since the distance δ1 is obtained based on the detection value β of the sensor 72, the process of obtaining the distance δ1 can be effectively automated, and the flow shown in FIG. 9 can be realized with a relatively simple algorithm.

In the molding system 70, the reference data acquisition flow shown in Fig. 6 can be omitted. Specifically, the parameters _x1 , y1, and _{zA -} Δ1 of the coordinate _Q1 ( _x1 , _y1 , _z1 ) = ( _x1 , _y1 , zA-Δ1) of the reference point P1 can be set in advance. For example, the molding machine 12 and the robot ₁₄ are modeled using 3D CAD, and a simulation is performed using these models to teach the operations of the robot 14 in steps S1 and S3 in a virtual space (so-called offline teaching).

Through this offline teaching, the coordinate Q ₁ (x ₁ , y ₁ , z _A -Δ1) of the reference point P1 can be set, and an operation program for making the robot 14 execute the operations of steps S1 and S3 can be constructed. Then, the processor 50 of the molding system 70 executes the flow of FIG. 9 after the installation position of the mold 20 is displaced, without executing the flow shown in FIG. 6, and executes the operations of steps S1 and S3 according to the operation program created in advance. Then, the processor 50 acquires position data RP4: coordinate Q ₄ (x ₄ , y ₄ , z ₄ )=(x ₂ -β ₀ , y ₁ , z _A -Δ1) in step S5, and adds the known β ₀ to the coordinate x ₄ of the coordinate Q ₄ to obtain x ₂ in step S6, and then obtains the distance δ1=x ₂ -x ₁ .

Next, other functions of the molding system 70 will be described with reference to FIG. 11. The processor 50 of the molding system 70 can obtain the deviation amount θ by executing the flow of FIG. 11 after displacing the installation position of the mold 20. Specifically, in step S11, the processor 50 moves the robot 14 to the reference position PR2.

Here, the reference position PR2 is determined in advance by the operator based on the mold 20 placed in the appropriate position. The reference position PR2 may be determined by teaching the robot 14 using the actual mold 20, or may be determined through the offline teaching described above.

The following describes a case where the operator _sets the reference position PR2 to a position _QPR2 (x1 - _βδ , _y1 , _z1 ) that is a distance _βδ to the left of the coordinate Q1 ( _x1 , _{y1 , z1} ) of the reference point P1. In this step 11, the processor 50 operates the robot 14 to position the working point 42a at the coordinate _QPR2 ( _x1 - _βδ , _y1 , _z1 ). The positional relationship between the working point 42a, the reference point P1, and the first reference point P2 at this time is shown in Figure 13.

In step S12, the processor 50 acquires the detection value β detected by the sensor 72 at this time. Then, in step S13, the processor 50 functions as the first distance acquisition unit 62 and obtains the distance δ1 as δ1=β _δ -β, as shown in Fig. 13. Then, in step S7, the processor 50 functions as the deviation amount acquisition unit 64 and acquires the deviation amount θ using the acquired distance δ1.

In this embodiment, when the mold 20 is placed at the appropriate position, the processor 50 may position the robot 14 at the reference position PR2 shown in Fig. 13 and obtain the detection value β _δ detected by the sensor 72 at this time. Then, after the installation position of the mold 20 is displaced, the flow of Fig. 11 may be executed and in step S13, the distance δ1 = β _δ - β may be calculated using the actually measured detection values β _δ and β.

Next, other functions of the molding system 10 will be described with reference to Figures 1 and 14. In this embodiment, the processor 50 functions as a device 60 equipped with a first distance acquisition unit 62, a deviation amount acquisition unit 64, a second distance acquisition unit 66, and a position acquisition unit 68. Here, in addition to the above-mentioned deviation amount θ, this device 60 acquires deviation amounts dx and dz (second deviation amounts) of the mold 20 in a direction perpendicular to the central axis A1 with respect to the correct position.

Specifically, due to a change in stage or the like, the installation position of the mold 20 may shift from the appropriate position around the central axis A1 and in a direction perpendicular to the central axis A1 (in this embodiment, within the x-z plane of the robot coordinate system C1). Or, when the actual molding machine 12 is assembled based on the ideal dimensions of the model of the molding machine 12 created through the above-mentioned offline teaching, the installation position of the mold 20 of the actual machine may shift from the appropriate position determined based on the ideal dimensions of the model of the molding machine 12 in a direction around the central axis A1 and in a direction perpendicular to the central axis A1.

An example of such a displacement of the installation position is shown in FIG. 15. In FIG. 15, the proper position of the mold 20 is indicated by a dotted line, and the central axis of the mold 20 placed in the proper position is indicated as A1'. In the example shown in FIG. 15, the mold 20 is displaced from the proper position by a displacement amount θ around the central axis A1, a displacement amount δx to the left, and a displacement amount dz upward.

To obtain these deviation amounts θ, δx, and dz, the processor 50 executes the flow shown in FIG. 16. The processor 50 starts the flow shown in FIG. 16 when it receives a deviation acquisition command from an operator, a higher-level controller, or a computer program after the installation position of the mold 20 has been displaced.

In step S21, the processor 50 executes a first position acquisition process. For example, in this step S21, the processor 50 acquires the position of a reference point P4, which will be described later. This step S21 will be described with reference to FIG. 17. After the start of step S21, in step S31, the processor 50 places the robot 14 at a predetermined initial position IP1.

This initial position IP1 is arbitrarily determined by the operator, for example, as a position where the working point 42a of the end effector 42 is spaced to the left from the left surface 22 of the mold 20. This initial position IP1 can be determined as the coordinates of the robot coordinate system C1 that sets the origin of the tool coordinate system C2.

In step S32, the processor 50 starts acquiring the detection value α from the sensor 17, similar to step S2 described above. In step S33, the processor 50 operates the robot 14 to move the end effector 42 (working point 42a) to the right from the initial position IP1, similar to step S3 described above.

In step S34, the processor 50 determines whether or not the most recently acquired detection value α has become the reference value α _0, as in the above-described embodiment. If the processor 50 determines YES, it proceeds to step S35, whereas if the processor 50 determines NO, it returns to step S33. When the processor 50 determines YES in step S34, the working point 42a of the robot 14 comes into contact with the reference point P4 ( FIG. 15 ) on the left surface 22 with a contact force CF ₀ corresponding to the reference value α ₀ .

In step S35, the processor 50 acquires the position of the reference point P4. Specifically, the processor 50 acquires the coordinates _Q5 (x5, y5, z5) in the robot coordinate system C1 of the origin of the tool coordinate system C2 (i.e., the working point 42a) as the position data RP5 of the robot 14 at this point in time (i.e., the point _in time _when YES is determined in _{step S34} ).

In this embodiment, since the origin of the tool coordinate system C2 is set at the working point 42a, the coordinate _Q5 indicates the coordinate of the reference point P4 on the left surface 22 with which the working point 42a comes into contact. Therefore, the processor 50 acquires the coordinate _Q5 ( _x5 , _y5 , _z5 ) as data indicating the position of the reference point P4.

Referring again to FIG. 16, the processor 50 executes a second position acquisition process in step S22. In this step S22, the processor 50 acquires the position of a second reference point P5, which will be described later. This step S22 will be described with reference to FIG. 17. After the start of step S22, in step S31, the processor 50 places the robot 14 at a predetermined initial position IP2. This initial position IP2 is determined as a position spaced a predetermined distance Δ3 upward from the initial position IP1 set in the above-mentioned step S21.

Then, similarly to step S21 described above, the processor 50 starts acquiring the detection value α in step S32, moves the end effector 42 (working point 42a) to the right from the initial position IP2 in step S33, and determines in step S34 whether the most recently acquired detection value α has become the reference value α _0. When the determination in step S33 is YES, the working point 42a of the robot 14 comes into contact with the reference point P5 ( FIG. 15 ) on the left surface 22 with a contact force CF ₀ corresponding to the reference value α ₀ .

In step S35, the processor 50 acquires the position of the reference point P5. Specifically, the processor 50 acquires coordinates _Q6 ( _x6 , _y6 , _z6 ) in the robot coordinate system C1 of the origin of the tool coordinate system C2 as position data RP6 of the robot 14 at this time. Note that _y6 may be equal to _y5 . In this embodiment, since the origin of the tool coordinate system C2 is set to the working point 42a, the coordinate _Q6 indicates the coordinate of the reference point P5 on the left surface 22 with which the working point 42a comes into contact. The processor 50 acquires coordinates _Q6 ( _x6 , _y6 , _z6 ) as data indicating the position of the reference point P5.

Thus, in this embodiment, the processor 50 functions as a position acquisition unit 68 (Figure 14) to acquire the position (coordinate _Q5 ) of reference point P4 (step S21) and the position (coordinate _Q6 ) of reference point P5 (step S22) based on the detection value α of the sensor 17.

The operator can also arbitrarily define reference points P4 and P5 as two points on the left surface 22 spaced apart from each other in the z-axis direction of the robot coordinate system C1 (in this embodiment, by setting the positions of the initial positions IP1 and IP2). Thus, one of reference points P4 and P5 corresponds to the "first reference point" and the other corresponds to the "second reference point."

Referring again to FIG. 16, in step S23, the processor 50 functions as the first distance acquisition unit 62 and acquires the distance between the reference point P4 and the reference point P5. Specifically, the processor 50 acquires the distance δ2 (first distance) between the reference point P4 and the reference point P5 in the x-axis direction of the robot coordinate system C1.

15, the distance δ2 in the x-axis direction between reference points P4 and P5 can be calculated as δ2 = x ₆ - x 5 from the coordinate x ₅ of the position (coordinate Q ₅ ) of reference point P4 acquired in step S21 and the coordinate x ₆ of the position (coordinate Q ₆ ) of reference point P5 acquired in step S22. In this way, the processor 50 obtains the distance δ2 based on the detection value _α detected by the sensor 17 for the reference points P4 and P5.

The processor 50 also acquires a distance Δ3 (second distance) between the reference point P4 and the reference point P5 in the z-axis direction of the robot coordinate system C1. For example, the processor 50 can calculate the distance Δ3 as Δ3 = z ₆ - _{z 5} from the coordinate z ₅ of the position (coordinate Q ₅ ) of the reference point P4 acquired in step S21 and the coordinate z ₆ of the position (coordinate Q ₆ ) of the reference point P5 acquired in step S22.

In this manner, in this embodiment, the processor 50 functions as a second distance acquisition unit 66 (FIG. 14) that acquires the distance Δ3 based on the detection value α of the sensor 17. Alternatively, the distance Δ3 in the z-axis direction between the reference points P4 and P5 is arbitrarily set by the operator as described above. Thus, the processor 50 can also acquire the distance Δ3 from the setting information set by the operator.

In step S24, the processor 50 functions as the deviation amount acquisition unit 64 and acquires the deviation amount θ using the distances δ2 and Δ3. Specifically, as shown in Fig. 15, the deviation amount θ is expressed as a known mathematical formula (trigonometric function) as θ = tan ^-1 (δ2/Δ3). Therefore, the processor 50 can obtain the deviation amount θ by applying the acquired distances δ2 and Δ3 to the known mathematical formula.

In step S25, the processor 50 executes a third position acquisition process. For example, in this step S25, the processor 50 acquires the position of a reference point P6 (third reference point) described later. This step S25 will be described with reference to FIG. 17. After starting step S25, in step S31, the processor 50 places the robot 14 at a predetermined initial position IP3.

The positional relationship of the robot 14, which is placed at the initial position IP3, with respect to the mold 20 is shown in FIG. 18. This initial position IP3 is arbitrarily determined by the operator, for example, as a position where the working point 42a of the end effector 42 is spaced downward from the lower surface 26 of the mold 20. This initial position IP3 can be determined as the coordinates of the robot coordinate system C1, which sets the origin of the tool coordinate system C2.

In step S32, the processor 50 starts acquiring the detection value α from the sensor 17, similar to steps S21 and S22 described above. In step S33, the processor 50 operates the robot 14 to move the end effector 42 (working point 42a) upward from the initial position IP3.

In step S34, the processor 50 determines whether the detection value α most recently acquired by the sensor 17 has become the reference value α ₀ '. This reference value α ₀ ' may be the same as the reference value α ₀ described above, or may be a different value. If the processor 50 determines YES, it proceeds to step S35, whereas if the processor 50 determines NO, it returns to step S33. When the processor 50 determines YES in step S34, the working point 42a of the robot 14 comes into contact with the reference point P6 on the lower surface 26 with a contact force CF ₀ ' corresponding to the reference value α ₀ '. This state is shown in FIG. 19.

In step S35, the processor 50 acquires the position of the reference point P6. Specifically, the processor 50 acquires the coordinates _Q7 (x7, y7, z7) in the robot coordinate system C1 of the origin of the tool coordinate system C2 (i.e., the working point 42a) as the position data RP7 of the robot 14 at this point in time (i.e., the point _in time _when YES is determined in step _S34 ).

In this embodiment, since the origin of the tool coordinate system C2 is set at the working point 42a, the coordinate _Q6 indicates the coordinate of the reference point P6 on the lower surface 26 with which the working point 42a comes into contact. Therefore, the processor 50 acquires the coordinate _Q7 ( _x7 , _y7 , _z7 ) as data indicating the position of the reference point P6.

Referring again to FIG. 16, in step S26, the processor 50 functions as the deviation amount acquisition unit 64 and acquires deviation amounts dx and dz (second deviation amounts) based on either the position (coordinate _Q5 ) of reference point P4 acquired in step S21 or the position (coordinate _Q6 ) of reference point P5 acquired in step S22, and the position (coordinate _Q7 ) of reference point P6 acquired in step S25.

An example of a method for obtaining the deviation amounts dx and dz based on the position of reference point P5 (coordinate Q ₆ ) and the position of reference point P6 (coordinate Q ₇ ) will be described below. If the coordinates of central axis A1 in the correct position in the xz plane of robot coordinate system C1 are (x _A , z _A ), the deviation amounts dx and dz can be found from the equations dx = φ - x _A and dz = ω - z _A , respectively. In these equations, φ and ω can be found from the following formulas using coordinates Q ₆ (x ₆ , y ₆ , z ₆ ) and coordinates Q ₇ (x ₇ , y ₇ , z ₇ ) and the deviation amount θ (= tan ^-1 (δ2/Δ3)) obtained in step S24 described above.

Here, "a" in the formula is the distance between the central axis A1 and the left surface 22, and "b" is the distance between the central axis A1 and the lower surface 26, which are predetermined by the operator as design dimensions. With this method, the processor 50 can determine the deviation amounts dx and dz based on the position (coordinate _Q6 ) of the reference point P5 and the position (coordinate _Q7 ) of the reference point P6. Although details are omitted, the processor 50 can also determine the deviation amounts dx and dz based on the position (coordinate _Q5 ) of the reference point P4 and the position (coordinate _Q7 ) of the reference point P6.

As described above, in this embodiment, the processor 50 acquires the deviation θ (first deviation) of the mold 20 from the correct position around the central axis A1, and the deviations dx and dz (second deviation) in the direction perpendicular to the central axis A1. With this configuration, it is possible to obtain the deviations of the mold 20 from the correct position in a wider variety of directions.

Next, further functions of the molding system 10 will be described with reference to Figs. 20 and 21. The processor 50 acquires the deviation amounts θ, dx, and dz by executing the flow shown in Fig. 20. The flow shown in Fig. 20 differs from the flow in Fig. 16 in steps S21' and S22'.

Below, step S21' will be described with reference to FIG. 21. After step S21' starts, in step S41, the processor 50 moves the robot 14 to the reference position PR7. Here, the reference position PR7 is determined in advance by the operator with the mold 20 placed in the appropriate position as a reference.

The reference position PR7 may be determined by teaching the robot 14 using the actual die 20, or may be determined through the above-mentioned offline teaching. Below, a case where the operator sets the reference position _PR7 to the reference point P7:Q7 ( _x1 , _y5 , _z5 ) in Fig. 15 will be described.

In step S41, the processor 50 first places the robot 14 at the initial position IP4, then sets the origin of the tool coordinate system C2 to the reference position PR7: coordinate _Q7 ( _x1 , _y5 , _z5 ), operates the robot 14, and moves the end effector 42 (working point 42a) rightward from the initial position IP4 toward the coordinate _Q7 . As a result, the working point 42a comes into contact with the reference point P4 on the left surface 22, and the movement of the end effector 42 is stopped.

In step S42, the processor 50 acquires the detection value _α2 detected by the sensor 17 when the movement of the end effector 42 stops in step S41 from the sensor 17. This detection value _α2 corresponds to the contact force _CF2 between the working point 42a and the reference point P4 when the movement of the end effector 42 stops in step S41.

In step S43, the processor 50 functions as the position acquisition unit 68 and detects the position of the reference point P4 based on the detection value _α2 . For example, the processor 50 refers to a data table DT2 indicating the relationship between the detection value α and the position of the reference point P4 (specifically, the x coordinate in the robot coordinate system C1), and searches for and acquires the x coordinate: _x5 corresponding to the detection value _α2 acquired in step S42. In this way, the processor 50 can acquire the coordinate _Q5 ( _x5 , _y5 , _z5 ) as the position of the reference point P4.

Step S22' will be described with continued reference to Fig. 21. After the start of step S22', in step S41, the processor 50 moves the robot 14 to a reference position PR8 that is determined based on the mold 20 placed at the appropriate position. The reference position PR8 may be determined by teaching the robot 14 using the actual mold 20, or may be determined through the above-mentioned offline teaching. Below, a case will be described in which the operator sets the reference position PR8 to the reference point P8: _Q8 ( _x1 , _y6 , _z6 ) in Fig. 15.

In step S41, the processor 50 first places the robot 14 at the initial position IP5, then sets the origin of the tool coordinate system C2 to the reference position PR8: coordinate _Q8 ( _x1 , _y6 , _z6 ), and operates the robot 14 to move the end effector 42 (working point 42a) rightward from the initial position IP5 toward the coordinate _Q8 . As a result, the working point 42a comes into contact with the reference point P5 on the left surface 22, and the movement of the end effector 42 is stopped.

The processor 50 may execute step S41 in steps S21' and S22' according to a pre-created operation program OP2. This operation program OP2 may be created by teaching the robot 14 the operation of step S41 using an actual mold 20 placed in an appropriate position, or it may be created through the offline teaching described above.

In step S42, the processor 50 obtains the detection value _α3 detected by the sensor 17 when the movement of the end effector 42 stops in step S41, similar to the above-mentioned step S21'. Then, in step S43, the processor 50 searches and obtains the x-coordinate: _x6 corresponding to the detection value _α3 from the data table DT2, similar to the above-mentioned step S21'. In this way, the processor 50 can obtain the coordinate _Q6 ( _x6 , _y6 , _z6 ) as the position of the reference point P5. Thereafter, the processor 50 executes the above-mentioned steps S23 to S26 as shown in FIG. 20, and sequentially obtains the distances δ2 and Δ3 and the deviation amounts θ, dx, and dz.

As described above, in this embodiment, the processor 50 obtains the positions (coordinates _Q5 , _Q6 ) of the reference points P4, P5 based on the detection values _α2 , _α3 detected by the sensor 17 when the robot 14 is moved to the reference positions PR7 (coordinate Q7 ₎ and PR8 (coordinate _Q8 ), and obtains the distances δ2 and Δ3 using the positions of the reference points P4, P5.

The second distance acquisition unit 66 and the position acquisition unit 68 shown in FIG. 14 can also be applied to the above-mentioned molding system 70. In this case, the processor of the molding system 70 can acquire the distances δ2 and Δ3 and the deviation amounts θ, dx, and dz based on the detection value β of the sensor 72 by executing the flow of FIG. 16.

For example, the processor 50 of the molding system 70 can execute steps S31 to S34 in Fig. 17, similarly to steps S1 to S4 in Fig. 9. Then, in step S35, the processor 50 of the molding system 70 may directly determine the positions (coordinates _Q5 , _Q6, and _Q7 ) of the reference points P4, P5, and P6 from the detection value β (=reference value _β0 ) of the sensor 72.

Alternatively, in the molding system 70, the reference value _β0 referenced in step S34 among steps S21, S22 and S25 may be common, and the processor 50 of the molding system 70 may acquire the position data RP5', RP6' and RP7' of the robot 14 at this time (i.e., the coordinates in the robot coordinate system C1 of the origin of the tool coordinate system C2) in the above-mentioned step S35 as data indicating the positions of the reference points P4, P5 and P6.

The position data RP5' and RP6' acquired at this time have coordinates spaced a distance _β0 to the left from the reference points P4 and P5, and the position data RP7' has coordinates spaced a distance _β0 downward from the reference point P6. Then, in step S26, the processor 50 can substitute the coordinates of the position data RP5', RP6', and RP7' into the formulas for calculating φ and ω described above, to calculate the deviation amounts dx and dz.

Moreover, the processor 50 of the molding system 70 can obtain the distances δ2 and Δ3 and the deviation amounts θ, dx, and dz by executing the flow of Fig. 20. For example, the processor 50 of the molding system 70 executes steps S41 and S42 of Fig. 21, similarly to steps S11 and S12 of Fig. 11 described above. Then, in step S43, the processor 50 of the molding system 70 may directly determine the positions (coordinates _Q5 and _Q6 ) of the reference points P4 and P5 from the detection value β of the sensor 72.

In this way, the processor 50 of the molding system 70 functions as a device 60 equipped with a first distance acquisition unit 62, a deviation amount acquisition unit 64, a second distance acquisition unit 66, and a position acquisition unit 68, and can acquire the distances δ2 and Δ3 and the deviation amounts θ, dx, and dz by executing the flow of FIG. 16 or FIG. 20. The processor 50 of the molding system 10 or 70 can also acquire the position of the reference point P6 by executing steps S41 to S43 shown in FIG. 21 as the above-mentioned step S25.

The processor 50 of the molding system 10 or 70 can also acquire the deviation amount dy (third deviation amount) of the mold 20 in the direction of the central axis A1 relative to the correct position. Below, the method in which the processor 50 of the molding system 10 acquires the deviation amount dy will be described with reference to FIG. 22.

First, the processor 50 of the molding system 10 executes the flow of steps S31 to S35 in Fig. 17 for the reference point P9 on the rear surface 30 of the mold 20 placed in the appropriate position shown by the dotted line in Fig. 22. As a result, the working point 42a of the robot 14 comes into contact with the reference point P9 on the rear surface 30, and the processor 50 acquires the coordinate _Q9 ( _x9 , _y9 , _z9 ) in the robot coordinate system C1 of the origin (working point 42a) of the tool coordinate system C2 as the position data RP9 of the robot 14 at this time.

In this embodiment, since the coordinate _Q9 ( _x9 , _y9 , _z9 ) indicates the coordinate of the reference point P9 with which the working point 42a comes into contact, the processor 50 acquires the coordinate _Q9 ( _x9 , _y9 , _z9 ) as reference data indicating the position of the reference point P9. In this way, the processor 50 acquires the position of the reference point P9: the coordinate _Q9 ( _x9 , _y9 , _z9 ) based on the detection value α.

After the installation position of the mold 20 is displaced as shown in Fig. 22, the processor 50 places the working point 42a at the same position in the xz plane as the coordinate _Q9 , that is, coordinate ( _x9 , _z9 ), as the initial position, and again executes the flow of steps S31 to S35 in Fig. 17. As a result, the working point 42a of the robot 14 comes into contact with the reference point P10 (fourth reference point) on the rear surface 30, and the processor 50 acquires the coordinate _Q10 ( _x9 , _y10 , _z9 ) in the robot coordinate system C1 of the origin (working point 42a) of the tool coordinate system C2 as the position data RP10 of the robot 14 at this time.

Since this coordinate _Q10 ( _x9 , _y10 , _z9 ) indicates the coordinate of reference point P10 with which working point 42a comes into contact, processor 50 functions as position acquisition unit 68 and acquires coordinate _Q10 ( _x9 , _y10 , _z9 ) as data indicating the position of reference point P10. In this way, based on detection value α detected by sensor 17 with respect to reference point P10, processor 50 acquires the position of reference point P10: coordinate _Q10 ( _x9 , _y10 , _z9 ).

Then, the processor 50 functions as the deviation amount acquisition unit 64 and uses the coordinates _Q9 and _Q10 to obtain the deviation amount dy from the formula dy= _y9 - _y10 . In this way, the processor 50 can acquire the deviation amount dy based on the position (coordinate _Q10 ) of the reference point P10. The processor 50 can also acquire the deviation amount dy by executing the flow of FIG. 21 for the reference point P10.

Although details will be omitted, it will be understood that the processor 50 of the molding system 70 can also obtain the deviation amount dy by executing the flow of FIG. 17 or FIG. 21 with respect to the reference point P10. With this configuration, it is possible to obtain the deviation amount of the mold 20 from the correct position in a wider variety of directions.

Next, referring to FIG. 23, further functions of the molding systems 10 and 70 will be described. In this embodiment, the processor 50 functions as a device 60 including a first distance acquisition unit 62, a deviation amount acquisition unit 64, a second distance acquisition unit 66, a position acquisition unit 68, and a correction unit 74.

The processor 50 corrects the working position when the robot 14 performs a predetermined task (removing a molded product or inserting an insert part into a molded product) on a molded product molded by the molding machine 12 using the mold 20, based on the deviation amounts θ, dx, dy, and dz obtained as described above. For example, the operation program OP0 for causing the robot 14 to perform the predetermined task specifies a teaching point TP for positioning the end effector 42 when the robot 14 performs the task at the working position.

The processor 50 may correct the teaching point TP defined in the operation program OP0 so as to displace it by the acquired deviation amounts θ, dx, dy, and dz. Alternatively, the processor 50 may correct the operation program OP0 so as to add an operation command for further moving the end effector 42 by the deviation amounts θ, dx, dy, and dz after the robot 14 positions the end effector 42 at the teaching point TP during operation.

In this way, the working position of the robot 14 can be corrected by the deviation amounts θ, dx, dy, and dz. With this configuration, even if the installation position of the mold 20 is displaced from the appropriate position, the working position of the end effector 42 can be corrected to correspond to the deviation amounts θ, dx, dy, and dz, and a specified operation (operation of removing the molded product or operation of inserting an insert part into the molded product) can be performed with high precision on the molded product molded by the mold 20.

In the embodiment shown in Fig. 5, the processor 50 assumes that the deviation θ is an extremely small angle and obtains the deviation θ as an approximate value (θ = tan ^-1 (δ1/Δ1)) by approximating Δ2 ≈ 0. However, in the embodiment shown in Fig. 5, the processor 50 may obtain a more accurate deviation _θ2 by setting an additional reference point P11 and executing the flow shown in Fig. 9 or 11 for the reference point P11.

This function will be described with reference to Fig. 24. The processor 50 executes the flow shown in Fig. 9 or 11 for the reference point P2 to obtain the distance δ1 and the deviation amount θ ₁ = tan ^-1 (δ1/Δ1) as an approximate value, and then executes the flow shown in Fig. 9 or 11 for the reference point P11 (first reference point) defined on the left surface 22 at a position spaced a distance Δ4 downward from the central axis A1 of the mold 20, and obtains the distance δ3 (first distance) between the reference point P11 and the reference point P3 in the x-axis direction of the robot coordinate system C1 in the above-mentioned step S6 or S13.

In this case, the following formula is satisfied between the distances δ1, δ3, Δ1, Δ2, and Δ4: δ1/(Δ1+Δ2)=δ3/(Δ2+Δ4). From this formula, the distance Δ2 can be calculated as Δ2=(δ3·Δ1-δ1·Δ4)/(δ1-δ3). The processor 50 can then calculate the accurate deviation θ ₂ as θ ₂ =tan ^-1 (δ1/(Δ1+Δ2))=tan ^-1 (δ3/(Δ2+Δ4)).

An example of the operation flow of this function will be described with reference to Fig. 25. In step S51, the processor 50 executes the flow shown in Fig. 9 or 11 for the reference point P2, and acquires the deviation amount θ ₁ =tan ^-1 (δ1/Δ1) as an approximate value. In step S52, the processor 50 judges whether the deviation amount θ ₁ acquired in step S51 is equal to or greater than a predetermined threshold value θ _th (θ ₁ ≧θ _th ). If θ ₁ ≧θ _th , the processor 50 judges YES and proceeds to step S53, whereas if it judges NO, it ends the flow shown in Fig. 25.

In step S53, the processor 50 executes the flow shown in FIG. 9 or FIG. 11 for the reference point P11 (first reference point) to obtain an accurate deviation θ ₂ = tan ^-1 (δ1/(Δ1+Δ2)) = tan ^-1 (δ3/(Δ2+Δ4)). Here, the larger the deviation θ ₁ is, the larger Δ2 becomes, and the error from the theoretical value of the deviation θ ₁ = tan ^-1 (δ1/Δ1) obtained under the assumption that Δ2 ≈ 0 becomes larger. According to the flow shown in FIG. 25, when the deviation θ ₁ obtained as an approximate value is large (i.e., when the error from the theoretical value becomes large), an accurate deviation θ ₂ can be obtained by executing step S53.

The above-mentioned Δ4 may be set so that the reference point P11 is closer to the reference point P2 than the central axis A1 in the z-axis direction of the robot coordinate system C1. With this configuration, the amount of movement of the end effector 42 by the robot 14 when executing step S53 can be reduced, thereby reducing the cycle time. When the processor 50 determines YES in step S52, it may execute the flow shown in FIG. 16 or FIG. 20.

In the above-described embodiment, instead of the sensor 17 capable of detecting the contact force CF or the sensor 72 capable of detecting the distance β, a sensor (e.g., a touch probe) capable of acquiring the position in the robot coordinate system C1 of any point on the surfaces 22, 24, 26, 28, 30 of the mold 20 may be used. In this case, the processor 50 can directly acquire the position data of the above-described points P1 (coordinate _Q1 ), P2 (coordinate _Q3 ), P4 (coordinate _Q5 ), P5 (coordinate _Q6 ), and P6 (coordinate _Q7 ) in the robot coordinate system C1 from the detection value of the sensor (touch probe). The sensor 17, the sensor 72, and the sensor capable of acquiring the positions (touch probe) all correspond to sensors that detect the surfaces 22, 24, 26, 28, 30 of the mold 20.

In the above embodiment, the reference points P2, P3, P4, P5, and P11 are set on the left surface 22 of the mold 20. However, this is not limiting, and the reference points P2, P3, P4, P5, and P11 may be set on any of the right surface 24, the lower surface 26, and the upper surface 28.

In the above-described embodiment, the sensor 17 can also be provided on the mold 20. For example, the sensor 17 is composed of a pressure sensor, a strain gauge, a piezoelectric element, or the like, and is installed on the left surface 22, the bottom surface, and the rear surface 30. Even in this case, the sensor 17 can detect the detection value α of the contact force CF when the robot 14 touches up these surfaces with the working point 42a. Similarly, the sensor 72 can be provided on the left surface 22, the bottom surface 26, and the rear surface 30 of the mold 20.

A computer program that causes the processor 50 to automatically execute the flows shown in Figures 6, 9, 11, 16, 17, 20, 21, and 25 may be stored in the memory 52. The mold is not limited to a rectangular shape, and may have any shape, such as a hexagon or octagon. In the above embodiment, the origin of the tool coordinate system C2 is set to the working point 42a, but the tool coordinate system C2 may be set to any position whose position in the robot coordinate system C1 is known.

The robot 14 is not limited to a vertical articulated robot, but may be any type of robot, such as a horizontal articulated robot or a parallel link robot. The present disclosure has been described above through the embodiments, but the above-mentioned embodiments do not limit the invention according to the claims.

Reference Signs List 10, 70 Molding system 12 Molding machine 14 Robot 16 Control device 17, 72 Sensor 20 Mold 22, 24, 26, 28, 30 Mold surface 60 Device 62 First distance acquisition unit 64 Deviation amount acquisition unit 66 Second distance acquisition unit 68 Position acquisition unit 74 Correction unit

Claims (14)

An apparatus for acquiring an amount of deviation of a mold installed in a molding machine from a proper position,
the mold has a first surface that is arranged to extend in a direction of a first axis perpendicular to a central axis of the mold when the mold is arranged at the predetermined appropriate position with respect to the molding machine;
The apparatus comprises:
a first distance acquisition unit that acquires a first distance in a direction of a second axis perpendicular to the central axis and the first axis between a first reference point and a second reference point that are defined on the first surface at positions spaced apart from each other in the direction of the first axis when an installation position of the mold is displaced from the appropriate position;
a deviation amount acquisition unit that acquires a first deviation amount around the central axis of the mold relative to the correct position using the first distance acquired by the first distance acquisition unit. a second distance acquisition unit that acquires a second distance between the first reference point and the second reference point in a direction of the first axis,
The apparatus according to claim 1 , wherein the deviation amount acquisition unit obtains the first deviation amount by applying the first distance and the second distance to a known mathematical formula. a sensor for detecting a contact force between a robot capable of moving forward and backward relative to the die as a detection value is provided on the robot or the die;
The device according to claim 1 or 2, wherein the first distance acquisition unit acquires the first distance based on a first detection value detected by the sensor when the robot touches up the first reference point. a sensor for detecting a distance between a robot capable of moving forward and backward with respect to the die as a detection value is provided on the robot or the die;
The device according to claim 1 or 2, wherein the first distance acquisition unit acquires the first distance based on a first detection value obtained by the sensor detecting the distance between the robot and the first reference point. The device according to claim 3 or 4, wherein the first distance acquisition unit determines the first distance based on position data of the robot when the first detection value becomes a predetermined reference value. The device according to claim 3 or 4, wherein the first distance acquisition unit acquires the first distance based on the first detection value detected by the sensor when the robot is moved to a predetermined reference position based on the mold placed in the appropriate position after the installation position is displaced. The device according to any one of claims 3 to 6, wherein the first distance acquisition unit acquires the first distance further based on a second detection value detected by the sensor with respect to the second reference point. a position acquisition unit that acquires a position of the first reference point based on the first detection value and acquires a position of the second reference point based on the second detection value,
The device according to claim 7 , wherein the first distance acquisition unit acquires the first distance using a position of the first reference point and a position of the second reference point. The mold further has a second surface arranged to extend in a direction of the second axis when the mold is disposed in the correct position;
the position acquisition unit further acquires a position of a third reference point defined on the second surface after the installation position is displaced based on a third detection value detected by the sensor with respect to the third reference point;
The apparatus of claim 8, wherein the deviation amount acquisition unit further acquires a second deviation amount of the mold relative to the correct position in a direction perpendicular to the central axis based on either the position of the first reference point or the position of the second reference point, and the position of the third reference point. The mold further has a third surface perpendicular to the central axis,
the position acquisition unit further acquires a position of a fourth reference point defined on the third surface after the installation position is displaced based on a fourth detection value detected by the sensor with respect to the fourth reference point;
The apparatus according to claim 8 or 9, wherein the deviation amount acquisition unit further acquires a third deviation amount of the mold relative to the correct position in a direction of the central axis, based on a position of the fourth reference point. A molding machine in which a mold is installed;
a robot that is provided to be movable toward and away from the die and performs a predetermined operation on a molded product molded by the molding machine using the die;
A molding system comprising the apparatus according to any one of claims 1 to 10. The molding system according to claim 11, further comprising a correction unit that corrects the work position of the robot when performing the specified work based on the amount of deviation acquired by the deviation amount acquisition unit. A method for acquiring an amount of deviation of a mold installed in a molding machine from a proper position, comprising:
the mold has a first surface that is arranged to extend in a direction of a first axis perpendicular to a central axis of the mold when the mold is arranged at the predetermined appropriate position with respect to the molding machine;
The processor:
When an installation position of the mold is displaced from the appropriate position, a first distance is obtained in a direction of a second axis perpendicular to the central axis and the first axis between a first reference point and a second reference point that are defined on the first surface at positions spaced apart from each other in the direction of the first axis;
Using the acquired first distance, a first amount of deviation about the central axis of the mold relative to the correct position is acquired. A computer program that causes the processor to execute the method of claim 13.

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