WO2005091093A1

WO2005091093A1 - Method and device for numerical control

Info

Publication number: WO2005091093A1
Application number: PCT/JP2004/003630
Authority: WO
Inventors: Katsuhide Sekikawa
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2004-03-18
Filing date: 2004-03-18
Publication date: 2005-09-29

Abstract

A method and a device for numerical control capable of performing extremely accurate processing even when the blade tip of a cutting tool is offset from the center of a shaft to which a cutting tool is fitted when a groove with a specified cross section is cut in a work by using the cutting tool having the blade tip matching the shape of the groove to be cut, wherein the position of the blade tip of the cutting tool with reference to the centerline of the rotatable shaft is pre-inputted as tool offset information, the point of the blade tip is used as a reference point for a program moving instruction based on the tool offset information, the correction amount of the blade tip angle of the cutting tool fitted to the rotatable shaft and a correction amount due to the offset of the cutting tool for moving, about a blade tip point, the front face of a cutter to a next moving instruction end point are obtained based on a vector from a present position to the next moving instruction end point, and based on these correction amounts, the rotatable shaft is rotated and X- and Y-axes are moved to control the attitude of the cutter for facing, about the blade tip point, the front face of the cutter toward the next moving instruction end point before the moving instruction is executed.

Description

Numerical control method and device ''

Technical field

The present invention relates to a numerical control method and an apparatus therefor, and more particularly to a method and an apparatus for numerically controlling a machine tool for cutting a groove having a predetermined cross-sectional shape in a workpiece using a cutting tool. book

Background art

Numerical control devices (hereinafter referred to as NC devices) control the position of a tool with respect to a work with a numerical value corresponding to the position, and process the work. The object can be processed easily and with high precision, and the productivity can be further improved.

By the way, as shown in FIG. 2, when cutting a groove having a predetermined cross-sectional shape into a work, a cutting tool having a cutting edge shape matching the groove shape is attached to a main shaft (Z axis) of a machine tool. The work is mounted on the X-Y axis table, and the machine tool is controlled by an NC unit to cut it. .

Such a cutting method is disclosed in, for example, Japanese Patent Application Laid-Open No. 3-228547.

In the cutting method disclosed in Japanese Patent Application Laid-Open No. 3-228 547, a tool is formed such that the center of the cutting edge thereof coincides with the center axis of the main shaft of the machine tool. Attach the tool so that the center of the cutting edge coincides with the center axis of the C-axis of the main shaft of the machine tool, and mount a peak on the X-Y-axis table. The workpiece is grooved by controlling the rotation angle of the main shaft around the c-axis so that the right angle is always maintained.

However, in the cutting method disclosed in JP-A-3-228547, when the tool is mounted on the center line of the C-axis of the spindle, a mounting error actually occurs. Had been included. For this reason, the impact was particularly large on machine tools equipped with numerical control capable of handling 10-nanometer and 1-nanometer orders in recent years, and this was an issue that cannot be ignored.

In addition, because the tool edge must be on the C-axis center line of the main spindle, there is a disadvantage that cutting cannot be performed from the front of the tool when the tip of the tool edge is offset from the center of the C-axis.

As another conventional technique, there is a technique disclosed in Japanese Patent Application Laid-Open No. HEI 8-118205. If the cutting edge of the tool attached to the spindle is offset with respect to the C-axis center axis of the machine tool spindle, the offset between the cutting edge and the C-axis center axis of the machine tool spindle is given. By controlling the rotation angle of the main spindle around the C axis so that the cutting edge of the tool always keeps a right angle to the forward direction of the tool movement trajectory, the machining can be easily performed without the perpetrator being aware of the offset. What was made possible is disclosed. However, in the technique disclosed in Japanese Patent Application Laid-Open No. Hei 8-118205, when cutting the side surface of a work with a hale bite, the cutting edge of a tool attached to the main shaft is offset with respect to the C-axis center axis of the main shaft of the machine tool. As shown in Fig. 2, this is a control method in which the tip of the tool edge has an offset with respect to the center of the C-axis when cutting a groove with a predetermined cross-sectional shape on the workpiece as shown in Fig. 2. The technology disclosed in JP-A-8-118205 is applied to control I can't. Disclosure of the invention

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and when a tool having a cutting edge having a predetermined cross-sectional shape is formed on a workpiece using a tool having a cutting edge that matches the shape of the groove to be cut, the tip of the tool blade tip is inserted into the tool. It is an object of the present invention to obtain a numerical control method and a numerical control method capable of performing extremely high-precision machining (machining closer to a program command) even when an offset is provided with respect to the center of the mounted shaft. .

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. In a numerical control method for performing a predetermined groove machining on a work by numerically controlling a machine tool having a tool mounted on a rotatable shaft, The position of the cutting edge of the tool based on the center line of the possible axis is input in advance as tool offset information, and the cutting edge point is used as a reference point of a program movement command based on the tool offset information, and the next movement from the current position is performed. Based on the vector to the command end point, the correction amount and the tool offset of the tool edge angle of the tool mounted on the rotatable axis to turn the front of the tool to the next movement command end point centering on the tool tip point By rotating the rotatable axis based on these correction amounts and moving the linear movement axes other than the rotatable axis based on these correction amounts, After executing the posture control so that the front of the blade is directed to the next movement command end point at the center, the movement command is executed.

Further, the rotatable axis is a C axis, and the linearly moving axes other than the rotatable axis are an X axis and a Y axis.

When the movement command from the current position to the next position is a curve command, the posture control is performed for each curve interpolation.

Also, numerical control of machine tools with tools mounted on rotatable axes In the numerical control device for performing a predetermined groove machining on a workpiece, a means for storing in advance a tool edge position of a tool with respect to a center line of the rotatable shaft as tool offset information; To move the front of the tool to the next movement command end point centering on the cutting edge point based on the vector from the current position to the next movement command end point based on the The correction amount of the blade edge angle of the tool mounted on the rotatable shaft and the correction amount by the tool offset are determined, and the rotatable shaft is rotated based on these correction amounts, and the rotation of the other than the rotatable shaft is performed. Means for controlling the posture by moving the linear movement axis so that the front of the blade is directed to the next movement command end point around the cutting edge point.

'Also, the rotatable axis is the C axis, and the linear movement axes other than the rotatable axis are the X axis and the Y axis.

Further, the apparatus is provided with means for performing the attitude control for each curve interpolation.

Further, means for performing the attitude control for each curve interpolation is provided in the interpolation unit.

Therefore, according to the present invention, a tool having a cutting edge that matches the shape of the groove to be cut is used. Even with an offset from the center, extremely high-precision machining (machining closer to a program command) can be performed.

In addition, when installing a tool during machining setup, it is possible to omit the work that took a lot of time to adjust whether the tool edge point is correctly on the C-axis center line. There is an effect that can be shortened. Brief Description of Drawings FIG. 1 is an explanatory diagram of a tool movement trajectory by tool tip point tangent control according to Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram showing a preferred machining example in which tool tip point tangent control according to Embodiment 1 of the present invention is used.

FIG. 3 is a diagram showing a mounting configuration of a tool (bite) according to Embodiment 1 of the present invention.

FIG. 4 is a shaft configuration diagram of an applicable machine tool according to Embodiment 1 of the present invention.

FIG. 5 is a configuration diagram of a numerical control device according to Embodiment 1 of the present invention.

FIG. 6 is a flowchart showing advance preparations according to Embodiment 1 of the present invention.

FIG. 7 is a flowchart showing a processing procedure of tool tip point tangent control according to Embodiment 1 of the present invention.

FIG. 8 is an explanatory diagram showing the relationship between the tip point of the cutting edge and the center point of the C-axis of the cutting tool according to Embodiment 1 of the present invention.

FIG. 9 is a view for explaining a specific processing method of tool tip point tangent control according to Embodiment 1 of the present invention.

FIG. 10 is an explanatory diagram showing interpolation of a curve according to Embodiment 2 of the present invention.

FIG. 11 is a flowchart showing a procedure of tool tip point tangent control according to Embodiment 2 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Example 1.

Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 9. First, an outline of the invention will be described with reference to FIGS. 1 to 4 in order to facilitate understanding of the invention.

That is, as shown in FIG. 2, the present invention uses a tool having a cutting edge that matches the groove shape to be cut, and performs shape cutting on the plane of the work 21 with the cutting tool 22. When a machining groove 23 having a predetermined cross-sectional shape is formed in 21, as shown in FIG. 1, cutting is performed while controlling the posture so that the front face 31 of the cutting edge of the tool 22 always faces the next movement command end point (hereinafter, referred to as the following). Tool tip point tangent control). In Fig. 1, reference numeral 37 denotes a locus specified by the machining program.In the example of tangent control at the tool tip point shown in Fig. 1, the tool entered from a is swung to the right and the C-axis center line 32 is moved outward. This is an example in which cutting is performed at the cutting edge front 31 while aligning the tool tip point 35 with the travel vector.

To explain this in more detail, machining is performed using a machine tool (X-axis 41, Y-axis 42, Z-axis (spindle) 43, and rotatable C-axis 44) as shown in Fig. 4. A tool 22 is mounted on the X-axis 41-Y-axis 42 table while a tool 22 is attached to the tip of the center of the axis. The tip point 35 has an offset with respect to the center of the C-axis of the Z-axis, and a tool that can perform machining as shown in Fig. 2) is attached, and the work 21 is attached to the X-axis 41-Y-axis 42 table. Attach.

In Fig. 3, (a) is a front view when the tool 22 is mounted on the Z-axis 43, (b) is a right side view of (a), (c) is a top view of (a), and Is the front of the cutting edge, 32 is the center line of the C axis of the Z axis 43, 33 is the width offset from the center line 32 of the C axis, 34 is the depth offset from the center line 32 of the C axis, and CD is the front direction of the cutting edge.

The X-axis 41, the Y-axis 42, and the C-axis 44 of the machine tool on which the tool 22 and the work 21 are mounted are NC-controlled so that the front end 31 of the tool 22 can be moved in the traveling direction. And cut it. When the cutting direction changes like the machining groove 23 in FIG. 2, as shown in FIG. Move the axis center line 32 (Because the machine tool shown in Fig. 4 cannot move the C axis center line 32 in the X-Y direction, the X-axis 41 and Y-axis are actually By moving the workpiece 42 and moving the workpiece 21, the C-axis center line 32 is relatively moved), and by rotating the C-axis by a predetermined angle, the front face 31 of the cutting edge also moves in the traveling direction according to the change. Turn to match. In addition, the operation of moving the buttocks opposite to the next cutting direction around the tool tip point 35 and then cutting is very similar to the situation where a groove is carved with a chisel of a print.

Next, details of the above-described tool tip point tangent control will be described.

The flow of processing inside the NC device 1 that performs this tool tip point tangent control is as shown in FIG. That is, as shown in FIG. 5, setting data such as NC machining programs, offset data, and parameters input from a man-machine interface (MMI) 2 such as a display device and a keyboard are input / output data processing units. Stored in memory 4 via 3.

The machining program stored in the memory 4 is analyzed by the machining program analysis processing unit 5 as in the conventional case. If the analysis data analyzed by the machining program analysis processing unit 5 is a tool tip point tangent control command (commanded by a G code such as G141 in the machining program), the tool tip point tangent control is performed. The movement data (movement data such as X-axis, Y-axis, C-axis commands, etc.) specified by the machining program is corrected and output to the interpolation processing unit 6. In addition, when the tool tip point tangent control end command (for example, G141.1 is commanded in the machining program) is analyzed, data for terminating the tool tip point tangent control is output to the interpolation processing unit 6. The detailed operation of the machining program analysis processing unit 5 will be described later.

The interpolation processing unit 6 creates axis interpolation data based on the data analyzed (and generated) by the machining program analysis processing unit 5, and performs axis control processing. Output to part 7.

The axis control processing section 7 performs acceleration / deceleration processing, etc., outputs the signals to the servo amplifier & the main axis amplifier 9, and controls the servo motor 10 to control the X, Y, and Z axes, and the main spindle motor 11 to control the C axis. Drive. '

If the data processed by the machining program analysis processing unit 5 is an auxiliary command (M command), the data is passed to the machine control processing unit 12 as in the conventional case, and the ladder processing unit 14 The machine controls (ATC control, coolant ON / OFF, etc.) by the action of the PLC interface 13 and DI / DO control unit (digital I / O control unit) 15. Next, the tool tip point tangent control of the machining program analysis processing unit 5 will be described.

First, the preparation for the tangent control of the tool tip point will be described with reference to FIGS. 3 and 6. FIG.

As shown in FIG. 6, the tool 22 shown in FIG. 3 is attached to the Z-axis 43 of the machine tool shown in FIG. 4 (step 61), and then the measurement function of the NC device 1 is used. As shown in (5), offset amounts 33 and 34 from the C-axis center line 32 are obtained (step 62) and stored in the memory 4 of the NC device 1. Also, as shown in FIG. 3 (c), the blade front direction CD is input to the memory 4 (step 63). Note that the blade front direction CD is input at an angle from a certain reference position (for example, the A position in FIG. 3 (c)).

Next, the tool tip point tangent control performed by the machining program analysis processing unit 5 will be described with reference to FIGS. 7 to 9. FIG.

The flowchart in FIG. 7 shows processing when the machining program analysis processing unit 5 reads a tool tip point tangent control command and is in a tool tip point tangent control mode.

That is, in FIG. 7, the tool offset amounts 33 and 34 are read out from the memory 4 Based on the tool offset amounts 33, 34 of the above, the tool tip point 35 is used as the reference for the program movement command (step 71). In FIG. 8, if the current position is PB (X, Y), the reference point can be represented by PB (X-OW, Y-OD).

Next, the next movement command is input from the machining program, and the movement position is obtained (Step 72). In this embodiment, in the case of arc cutting, data approximating the arc with minute line segments (straight lines) is given in advance by the CAD / CAM device.

Next, it is determined whether or not the program has ended (tool tip point tangent control end command) (step 73), and if the program has ended, the process ends (step 77).

If there is a next movement command in step 73, the correction amount based on the cutting edge correction angle and the tool offset is calculated using the vector from the current position to the next movement end point (step 74).

Specifically, as shown in FIG. 9 (a) and the following equation, the moving direction から is obtained from the coordinates of the next cutting edge moving point P based on the current position B (X1, Y1).

(Blade correction angle)

SIN Θ = Y1 / SQRT (X1 * X Y1 * Y1)

COS θ = Χ1 / SQRT (X1 * X1, Υ1 * Υ1) Next, as shown in Fig. 9 (b) and the following equation, the point Q (X2, Y2) on the center of the C axis is Rotate the center of the angular coordinate for the difference (0-CD) from the current cutting edge direction to obtain Q '(Χ2', Υ2 ').

(Tool offset)

X2 '= X2 * COS (Θ-CD)-Y2 * SIN (Θ -CD)

Y2 '= X2 * SIN (Θ-CD) + Y2 * COS (θ-CD) Next, move the X-axis and Y-axis to X2' and Y2 'using the center B arc command. At the same time, rotate the C axis by (（—CD) (step 75). As a result, the front of the cutting edge can be directed to the movement end point.

Next, a program movement command is executed to move to the end point (step 76). this By repeating this until the program ends, it is possible to obtain the trajectory of the tangent control of the tool tip point as shown in Fig. 1. Example 2.

Next, a second embodiment will be described mainly with reference to FIGS. 10 and 11. FIG.

The second embodiment is an example in which the tool tip point tangent control as shown in FIG. 1 is performed by the interpolation processing unit 6 instead of the processing program analysis processing unit 5 in FIG.

That is, when the machining program analysis processing unit 5 analyzes a curve command or the like in the tool tip point tangent control mode, the analysis data is output to the interpolation processing unit 6 as it is, and the tool tip point tangent control described above is performed by the interpolation processing unit 6. In Fig. 10 (a), if a curve command (arc command) from the current position 101 to the next position 102 is given in the tool tip point tangent control mode, the curve command The processor 6 approximates the curve by dividing it into minute points and connecting each point with a straight line as shown in Fig. 10 (b). I do.

For this reason, according to this embodiment, in the case of a curve command, as in the first embodiment, data approximated to a curve by a minute line segment (tt line) is created in advance by a CAD / CAM apparatus, and the data is processed by a machining program. There is no need to input to the analysis processing unit 5.

FIG. 11 shows an operation flow of the NC device in this case.

In the tool tip point tangent control mode, a curve command (for example, G02 (03) Xx Yy Ii Jj Ff;, G02 (03): G code for circular interpolation, Xx Yy: End point coordinates, Ii Jj: Arc center coordinates, Given Ff: feed rate, the machining program analysis processing unit 5 analyzes the curved line command data and obtains the tool tip point contact as described in the first embodiment. The analysis data is passed to the interpolation unit 6 (without performing line control) (step 1 1 1). The interpolation unit 6 determines the end point position of the curve command based on the commanded data and the current position (step 1 12). Next, the curve is partly divided into small portions (interpolation units) from the starting point to a predetermined distance (interpolation unit), and a curve approximation is performed by connecting the divided points with a straight line. At the same time, the amount of movement of the divided minute line is calculated (step 114). Next, the tool tip point tangent control described in the first embodiment is performed for each minute line segment (step 1 15), and the movement command is executed (step 1 16). Step 6 is repeated until the end point of the arc. Industrial applicability

As described above, the numerical control method and the numerical control apparatus according to the present invention are suitable for the numerical control method and the numerical control method used for machining the shape on a plane with a bite tool or the like.

Claims

The scope of the claims

1. In a numerical control method for performing a predetermined groove machining on a workpiece by numerically controlling a machine tool having a tool mounted on a rotatable axis, a cutting edge position of the tool with respect to a center line of the rotatable axis is determined. Based on the vector from the current position to the end point of the next movement command, based on the vector from the current position to the end point of the next movement command, The amount of correction of the edge angle of the tool mounted on the rotatable shaft and the amount of correction by the tool offset for moving to the next movement command end point around the point of the cutting edge are determined, and based on these corrected amounts, By rotating the rotatable axis and moving the linear movement axis other than the rotatable axis, the attitude control is performed so that the front of the tool faces the next movement command end point around the cutting edge point. After Tsu, numerical control how, characterized in that executing the move command.

2. The numerical control method according to claim 1, wherein the rotatable axis is a C axis, and the linear moving axes other than the rotatable axis are an X axis and a Y axis. .

3. The numerical control method according to claim 1, wherein the attitude control is performed for each curve interpolation when the movement command from the current position to the next position is a curve command.

4. In a numerical control device that performs a predetermined groove machining on a work by numerically controlling a machine tool having a tool mounted on a rotatable shaft, a cutting edge position of the tool with respect to a center line of the rotatable shaft is determined. Means for storing in advance as tool offset information, and using the tool tip information as a reference point for a program movement command based on the tool offset information, and based on a vector from the current position to the next movement command end point, the front of the tool is determined. To the next movement command end point 3 to determine the correction amount of the blade edge angle of the tool mounted on the rotatable shaft and the correction amount by the tool offset, and rotate the rotatable shaft based on these correction amounts and rotate the rotatable shaft. Means for performing posture control by moving a linear movement axis other than the above so that the front of the blade is directed to the next movement command end point centering on the cutting edge point.

5. The numerical control device according to claim 4, wherein the rotatable axis is a C axis, and the linear moving axes other than the rotatable axis are an X axis and a Y axis. '

6. The numerical control device according to claim 4, further comprising: means for performing the attitude control for each curve interpolation.

7. The numerical controller according to claim 6, wherein the means for performing the attitude control for each curve interpolation is provided in an interpolation unit.