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WO2018185993A1 - Dispositif de commande de vitesse d'arbre principal - Google Patents

Dispositif de commande de vitesse d'arbre principal Download PDF

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Publication number
WO2018185993A1
WO2018185993A1 PCT/JP2018/001000 JP2018001000W WO2018185993A1 WO 2018185993 A1 WO2018185993 A1 WO 2018185993A1 JP 2018001000 W JP2018001000 W JP 2018001000W WO 2018185993 A1 WO2018185993 A1 WO 2018185993A1
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WIPO (PCT)
Prior art keywords
chatter
spindle
rotational speed
tool
rotation speed
Prior art date
Application number
PCT/JP2018/001000
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English (en)
Japanese (ja)
Inventor
勝彦 大野
静雄 西川
将隆 阪本
謙吾 河合
Original Assignee
Dmg森精機株式会社
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Filing date
Publication date
Application filed by Dmg森精機株式会社 filed Critical Dmg森精機株式会社
Publication of WO2018185993A1 publication Critical patent/WO2018185993A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q15/00—Automatic control or regulation of feed movement, cutting velocity or position of tool or work
    • B23Q15/007—Automatic control or regulation of feed movement, cutting velocity or position of tool or work while the tool acts upon the workpiece
    • B23Q15/12—Adaptive control, i.e. adjusting itself to have a performance which is optimum according to a preassigned criterion
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/404—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia

Definitions

  • the present invention relates to a spindle rotational speed adjusting device that monitors whether or not regenerative chatter occurs during machining using a machine tool, and adjusts the rotational speed of a main spindle to eliminate the regenerative chatter when the regenerative chatter occurs. .
  • This stability limit diagram shows that when the spindle rotational speed is a value obtained by dividing the natural frequency of the tool by the number of blades of the tool, the limit cutting depth of the tool shows a peak, that is, the stable region has a peak. It has a so-called stable pocket (primary stable pocket), and further has a high-order stable pocket at each spindle rotational speed obtained by dividing the spindle rotational speed corresponding to the primary stable pocket by an integer of 2 or more.
  • the operator can instantly visually recognize the relationship between the spindle rotation speed at which regenerative chatter does not occur and the cutting depth of the tool, and efficient machining that does not cause regenerative chatter. Conditions can be set easily.
  • the operator can set efficient machining conditions within a range in which regenerative chatter does not occur by using the stability limit diagram displayed on the apparatus as a reference.
  • Patent Document 2 it is expected that the chatter will be suppressed by changing the spindle rotational speed to the predicted stable rotational speed.
  • the predicted stable rotational speed disclosed in Patent Document 2 is not necessarily the spindle rotational speed corresponding to the above-described stable pocket. For this reason, the method disclosed in Patent Document 2 is not expected. The street was unable to suppress regenerative chatter.
  • the spindle speed of the stable pocket is calculated based on the natural frequency of the tool, while the predicted stable speed disclosed in Patent Document 2 is based on the actual regenerative chatter frequency.
  • the actual regenerative chatter frequency does not always match the natural frequency of the tool, and the expected stable rotational speed in Patent Document 2 is actually the same as the spindle rotational speed of the stable pocket. I have not done it.
  • the present invention has been made in view of the above circumstances, and monitors whether or not regenerative chatter occurs during machining using a machine tool.
  • the regenerative chatter is compared with the conventional one.
  • An object of the present invention is to provide a spindle rotational speed adjusting device that can be more effectively eliminated.
  • the present invention for solving the above problems is an apparatus for adjusting the spindle rotational speed of a machine tool controlled by a numerical control device,
  • a vibration detection unit that detects vibration generated in the tool by processing and outputs a signal related to the detected vibration;
  • the vibration signal output from the vibration detection unit is analyzed to monitor whether or not regenerative chatter occurs in the tool.
  • the detection signal and data related to the regenerative chatter frequency are displayed.
  • a chatter detector to output, While receiving the data related to the detection signal and the playback chatter frequency output from the chatter detection unit, and continuously receiving the detection signal, at a predetermined amount of change at a predetermined time interval, A speed adjustment signal for increasing or decreasing the spindle rotation speed is transmitted to the numerical control device, a rotation speed adjustment process for increasing or decreasing the spindle rotation speed is executed, and each time the speed adjustment signal is transmitted, playback chatter is performed. Executes a detection process for detecting whether or not the state can not be resolved, and stops transmission of the speed adjustment signal to the numerical control device when the detection signal is not received from the chatter detection unit.
  • a main spindle rotational speed adjusting device comprising: a rotational speed adjusting unit that executes countermeasure processing.
  • the vibration generated in the tool being processed is detected by the vibration detection unit, and is output from the vibration detection unit to the chatter detection unit as a vibration signal.
  • the vibration signal output from the vibration detection unit is analyzed by the chatter detection unit to monitor whether or not regenerative chatter has occurred in the tool.
  • the detection signal is output from the chatter detection unit. Output to the rotation speed adjustment unit.
  • the spindle rotation speed adjustment unit when the detection signal is received from the chatter detection unit, the spindle rotation speed is increased by a predetermined change amount at a predetermined time interval while the detection signal is continuously received or A speed adjustment signal to be decreased is transmitted to the numerical controller, and a process of increasing or decreasing the spindle rotation speed stepwise by the amount of change is executed.
  • the stability limit diagram is a diagram showing the correlation between the rotational speed of the spindle and the limit cutting depth of the tool that causes regenerative chatter, in other words, in the relationship between the spindle rotational speed and the cutting depth of the tool.
  • FIG. 5 is a diagram showing a boundary between a stable region where no regenerative chatter occurs and an unstable region where regenerative chatter occurs.
  • the limit cutting depth of the tool shows a peak, that is, the stable region is It has a so-called stable pocket showing a peak, and further has a high-order stable pocket at each spindle rotational speed obtained by dividing the spindle rotational speed corresponding to the primary stable pocket by an integer of 2 or more.
  • An example of this stability limit diagram is shown in FIG.
  • the cutting depth of the tool when regenerative chatter occurs is smaller than the limit cutting depth of the stable pocket on the high speed side than the spindle rotation speed at that time and smaller than the limiting cutting depth of the stable pocket on the low speed side.
  • the relationship between the spindle rotation speed and the cutting depth of the tool is in the stable pocket in the stability limit diagram, that is, an unstable region where regenerative chatter occurs. Therefore, it is possible to realize a state in which the chatter is shifted to a stable region where regenerative chatter does not occur, thereby eliminating (or suppressing) regenerative chatter occurring in the tool (see FIG. 5).
  • the rotation speed adjustment unit stops transmission of the speed adjustment signal to the numerical control device when the playback chatter is eliminated by the above processing and no detection signal is received from the chatter detection unit.
  • the spindle rotation speed and the tool cutting depth will be increased even if the spindle rotation speed is increased stepwise. It is considered that the regenerative chatter generated in the tool cannot be eliminated because the relationship with the depth cannot be shifted to the stable region.
  • the cutting depth of the tool is larger than the critical cutting depth of the stable pocket on the lower speed side than the spindle rotation speed at that time, the spindle rotation speed and the tool Since the relationship with the cutting depth cannot be shifted to the stable region, it is considered that the regenerative chatter generated in the tool cannot be eliminated also in this case.
  • a detection process is performed to detect whether or not the regenerative chatter cannot be eliminated. Executed and when it is detected that the regenerative chatter cannot be eliminated, the rotation speed adjustment unit sends a cutting stop signal to the numerical control device to stop cutting or adjust the spindle rotation speed. At least one of the countermeasure processes for notifying the outside of the fact that it is stopped or the playback chatter cannot be eliminated is executed.
  • the machining in the regenerative chatter state can be stopped by stopping the cutting by retracting the feed shaft.
  • the spindle rotation speed is increased in stages, the higher rotation speed causes an increase in vibration, which may increase the adverse effects of chatter vibration on tools and workpieces.
  • the main spindle rotational speed adjusting device when regenerative chatter occurs during machining, the main spindle rotational speed is set at a predetermined change amount from the rotational speed adjusting unit at predetermined time intervals.
  • a speed adjustment signal for increasing or decreasing is transmitted to the numerical controller, and the spindle rotational speed is increased or decreased stepwise by the amount of change. Therefore, if the cutting depth of the tool when regenerative chatter occurs is the depth of cut that can eliminate regenerative chatter by adjusting the main spindle rotational speed, such adjustment of the main spindle rotational speed should be performed. By doing so, it is possible to effectively eliminate regenerative chatter compared to the conventional case.
  • the cutting depth of the tool when regenerative chatter occurs is the depth of cut that cannot be relieved by adjusting the spindle rotation speed, regenerative chatter cannot be eliminated. Therefore, by taking appropriate measures that can be taken, it is possible to prevent unwanted adverse effects on the tool or workpiece by changing the spindle rotational speed.
  • the rotation speed adjustment unit transmits the spindle rotation speed S i [min ⁇ 1 ] and the playback chatter frequency ⁇ i [Hz] at that time.
  • the coefficient k i is calculated by the following formula 1 based on the number N of blades of the tool, and is calculated while the detection signal is continuously received from the chatter detection unit.
  • the value of the coefficient k i changes, it is possible to adopt a mode in which it is determined that the playback chatter cannot be eliminated and the countermeasure process is executed.
  • k i (60 ⁇ ⁇ i ) / (N ⁇ S i )
  • i is an integer of 1 or more, and means the number of changes in the spindle rotation speed.
  • N is an integer equal to or greater than 1
  • k i is an integer obtained by rounding down the fractional part.
  • the coefficient k i represents the order of the stability lobe (individually convex curve) in the stability limit diagram, and when the value of this coefficient k i changes, the cutting depth of the current tool Therefore, it is determined that the relationship between the cutting depth of the tool and the spindle rotation speed cannot be shifted to the stable region by adjusting the spindle rotation speed.
  • each time the rotational speed adjustment unit transmits the speed adjustment signal in the detection process the playback chatter frequency output from the chatter detection unit at that time and the playback chatter frequency output last time And when the calculated difference value exceeds a predetermined reference value while continuously receiving the detection signal from the chatter detecting unit, playback is performed. It can be determined that the chatter cannot be eliminated and the countermeasure process can be executed.
  • the regenerative chatter phenomenon has a characteristic that the regenerative chatter frequency gradually increases (continuously increases) as the spindle rotation speed increases in the region corresponding to each stability lobe in the stability limit diagram.
  • the characteristic that the playback chatter frequency suddenly decreases when moving from the high-order stable lobe region to the low-order stable lobe region, in other words, when crossing the stable pocket, in the process of increasing the spindle rotation speed Have
  • a difference value (change amount) between the playback chatter frequency output from the chatter detection unit and the playback chatter frequency output last time is predetermined. If the value exceeds the reference value, it is determined that the spindle rotation speed has fluctuated across the stable pocket. In this case, the current tool depth of cut exceeds the limit depth of the stable pocket. In addition, it is determined that the relationship between the cutting depth of the tool and the spindle rotation speed cannot be shifted to the stable region by adjusting the spindle rotation speed.
  • the rotation speed adjustment unit when the rotation speed adjustment unit receives the detection signal from the chatter detection unit, before executing the rotation speed adjustment process, the spindle rotation speed S 0 [min ⁇ 1] and regenerative chatter frequency omega 0 [Hz], and on the basis of the number of teeth N of the tool, calculates a coefficient k 0 before treatment by equation 2 below, in the rotational speed adjustment process, the coefficient k 0 is previously When the value is larger than a predetermined value, the spindle rotational speed is decreased, and when the coefficient k 0 is smaller than a predetermined value, the spindle rotational speed is increased or decreased.
  • the aspect comprised so that it may be made can be taken.
  • k 0 (60 ⁇ ⁇ 0 ) / (N ⁇ S 0 )
  • k 0 is an integer obtained by truncating the decimal point.
  • the rotation speed adjustment unit of this aspect when the detection signal is received from the chatter detection unit, before executing the rotation speed adjustment process, first, the main shaft rotation speed S 0 [min ⁇ 1 ] and the playback chatter frequency are obtained. Based on ⁇ 0 [Hz] and the number N of blades of the tool, the coefficient k 0 before processing is calculated by the above formula 2. This coefficient k 0 represents the order of the stability lobe in the stability limit diagram.
  • the stability limit diagram regarding regenerative chatter shows that when the order of the stability pocket exceeds a certain value and becomes higher, the limit cutting depth tends to gradually increase as the spindle rotation speed decreases. This is generally called a process damping region (see FIG. 5).
  • the rotational speed adjustment unit sets the spindle rotational speed to a predetermined value in the subsequent processing.
  • the time is reduced in a stepwise manner at a time interval and a predetermined change amount, that is, by reducing the spindle rotational speed as long as the chatter detection signal is not lost, the spindle rotational speed is guided into the process damping region, and the coefficient
  • the spindle rotational speed is changed step by step at a predetermined time interval and a predetermined change amount. Increase or decrease. Thereby, the spindle rotational speed can be more effectively guided to the stable region.
  • the rotational speed adjusting unit receives the detection signal from the chatter detecting unit, the rotational speed adjusting unit, based on the playback chatter frequency ⁇ 0 [Hz] at that time and the number N of blades of the tool, before executing each process. Then, the stable rotational speed S S [min ⁇ 1 ] of the main spindle is estimated by the following formula 3, and a speed command signal related to the estimated stable rotational speed S S is transmitted to the numerical control device, so that the main spindle rotational speed is determined. estimated is changed to a stable rotational speed S S, it can be the case even after the change to receive the detection signal from the chatter detection unit, taking the configured manner to perform the respective processing.
  • S S (60 ⁇ ⁇ 0 ) / (N ⁇ k)
  • k is an arbitrary integer of 1 or more.
  • the rotation speed adjustment unit of this aspect when the detection signal is received from the chatter detection unit, the playback chatter frequency ⁇ 0 [Hz] at that time and the number N of blades of the tool are set before executing the respective processes. Based on the above equation 3, the stable rotational speed S S [min ⁇ 1 ] of the main spindle is estimated, and a speed command signal related to the estimated stable rotational speed S S is transmitted to the numerical control device. is changed to a stable rotational speed S S were estimated.
  • the stable rotational speed S S is the rotational speed corresponding to the k-th order stable pot in the stability limit diagram, by adjusting the spindle rotation speed to the stable rotational speed S S, to eliminate the regenerative chatter could be possible.
  • this stable rotational speed S S is an approximate value and does not necessarily match the actual rotational speed corresponding to the stable pocket. Therefore, even if the spindle rotational speed is adjusted to such a stable rotational speed S S , playback chatter is not generated. If it is not resolved, a process of increasing or decreasing the spindle rotational speed in a stepwise manner at a predetermined time interval and a predetermined amount of change is performed to eliminate playback chatter.
  • the main spindle rotational speed is greatly changed. since increased risk of the tool defect such, when setting the value of the coefficient k is, who provided the somewhat limited based on the coefficient k 0 is preferable.
  • the rotation speed adjustment unit determines whether or not the position of the tool obtained from the numerical control device is an air cut position when executing the process of stopping the cutting in the countermeasure process.
  • the position becomes the air cut position it is possible to adopt an aspect configured to execute a process of transmitting a cutting stop signal to the numerical controller and stopping the rotation of the spindle.
  • the rotation speed adjustment unit performs cutting according to the change in the spindle rotation speed so that the amount of cutting per blade of the tool does not fluctuate when the numerical control device changes the spindle rotation speed.
  • the mode comprised so that the signal which changes a feed rate might be transmitted to the said numerical control apparatus can be taken.
  • the cutting amount per blade of the tool in other words, the feed amount per blade does not vary, so the theoretical surface of the workpiece surface processed by the tool
  • the roughness can be made constant, and the machining accuracy can be prevented from deteriorating by changing the spindle rotational speed.
  • the main spindle rotational speed adjusting device when regenerative chatter occurs during machining, the main spindle rotational speed is changed at a predetermined change amount from the rotational speed adjusting unit at predetermined time intervals.
  • a speed adjustment signal for increasing or decreasing is transmitted to the numerical controller, and the spindle rotational speed is increased or decreased stepwise by the amount of change. Therefore, if the cutting depth of the tool when regenerative chatter occurs is the depth of cut that can eliminate regenerative chatter by adjusting the main spindle rotational speed, such adjustment of the main spindle rotational speed should be performed. By doing so, it is possible to eliminate the regenerative chatter more effectively than in the prior art.
  • the cutting depth of the tool when regenerative chatter occurs is a cutting depth at which regenerative chatter cannot be eliminated by adjusting the spindle rotation speed, this can be detected and taken accordingly. Since measures are taken, it is possible to prevent excessive adverse effects on tools and workpieces.
  • FIG. 1 is a block diagram showing a schematic configuration of a spindle rotational speed adjustment device, a numerical control device, and the like according to the present embodiment.
  • the spindle rotational speed adjusting device 1 of this example is an apparatus that adjusts the rotational speed of the spindle of the machine tool 20 that is numerically controlled by the numerical controller 10.
  • the numerical controller 10 controls the spindle rotational speed of the machine tool 20 to be adjusted.
  • the machine tool 20 of this example includes a bed 21, a column 22 erected on the bed 21, and an arrow Z-axis direction on the front surface (surface on the processing region side) of the column 22.
  • a spindle head 23 movably provided on the head, a spindle 24 held by the spindle head 23 so as to be rotatable about the axis, and a bed 21 below the spindle head 23 so as to be movable in the Y-axis direction.
  • a Y-axis feed mechanism 28 for moving, a Z-axis feed mechanism 27 for moving the spindle head 23 in the Z-axis direction, and a spindle motor (not shown) for rotating the spindle 24 are provided.
  • the X-axis feed mechanism 29, the Y-axis feed mechanism 28, the Z-axis feed mechanism 27, and the spindle motor (not shown) are driven to rotate the spindle 24 about its axis, and the spindle 24 and the table 26 are moved.
  • the workpiece W fixed on the table 26 is processed by the tool T mounted on the spindle 24.
  • the tool T is mounted on the main shaft 24 while being held by the tool holder TH.
  • FIG. 2 shows an end mill as an example of the tool T.
  • the numerical control device 10 includes an NC program execution unit 11, an NC program storage unit 12, a spindle control unit 13, a feed control unit 14, a tool data storage unit 15, a display control unit 16, and the like. Is connected to a display device 17 having a display as appropriate.
  • the numerical control device 10 is composed of a computer including a CPU, RAM, ROM and the like.
  • the NC program storage unit 12 and the tool data storage unit 15 are composed of an appropriate storage medium such as a RAM, and the NC program execution unit 11, the spindle control unit 13, the feed control unit 14 and the display control unit 16 are configured by a computer program. Function is realized.
  • the spindle control unit 13 is a control unit that controls the operation of a spindle motor (not shown).
  • the spindle control unit 13 receives a control signal (command signal) related to the spindle rotation speed from the NC program execution unit 11, and The spindle motor (not shown) is controlled so that the rotation speed of the spindle 24 becomes the commanded rotation speed.
  • the feed control unit 14 is a control unit that controls the operation of the X-axis feed mechanism 29, the Y-axis feed mechanism 28, and the Z-axis feed mechanism 27. For example, each feed axis from the NC program execution unit 11 is controlled. A control signal related to the movement position and movement speed for (X axis, Y axis and Z axis) is received, and the corresponding X axis feed mechanism 29, Y axis feed mechanism 28 and Z axis feed mechanism 27 are driven and commanded. The main shaft 24 and the table 26 are relatively moved in the three-dimensional space so that the commanded positional relationship is obtained at the moving speed.
  • the NC program execution unit 11 reads out the NC program stored in the NC program storage unit 12 and sequentially analyzes the NC program to generate a control signal according to the command.
  • the generated control signal is transmitted to the spindle control unit. 13 and the transmission control unit 14 are transmitted.
  • the NC program stored in the NC program storage unit 12 is executed by the NC program execution unit 11, and the spindle motor (see FIG. (Not shown) is driven by the spindle control unit 13 so that the spindle 24 rotates about its axis, and the X-axis feed mechanism 29, Y-axis feed mechanism 28, and Z-axis feed mechanism 27 are fed to the feed control unit 14.
  • the workpiece W on the table 26 is machined by the tool T mounted on the spindle 24 as the spindle 24 and the table 26 move relative to each other in the three-dimensional space.
  • the tool data storage unit 15 is associated with information on the tool T used in the machine tool 20, such as the tool number, the type of the tool T, the number of blades of the tool T, the material of the tool T, and the like. Stored.
  • the display control unit 16 controls display on the display device 17. For example, under the control of the display control unit 16, the NC program stored in the NC program storage unit 12 is displayed on the display device 17, and the coordinate position of the tool T in the three-dimensional space is displayed on the display device. 17 is displayed.
  • the spindle rotation speed adjustment device 1 includes an acceleration sensor 2 provided at the lower end portion of the spindle head 23 and an arithmetic processing device 3 (see FIGS. 1 and 2).
  • the arithmetic processing unit 3 includes a general computer including a CPU, a ROM, a RAM, and the like, and includes a chatter detection unit 4 and a rotation speed adjustment unit 5 whose functions are realized by a computer program.
  • the acceleration sensor 2 detects vibration generated in the tool T when the workpiece W is being machined by the tool T, and outputs a signal corresponding to the vibration to the chatter detection unit 4. The detection of vibration by the acceleration sensor 2 is always executed while the machining is being performed.
  • the chatter detection unit 4 receives a signal related to vibration continuously output from the acceleration sensor 2, analyzes the received signal by Fourier analysis (frequency analysis) at a predetermined sampling interval, and is generated in the tool T. Calculate the frequency and magnitude of the vibration. Then, when the magnitude of the obtained vibration exceeds a predetermined threshold value, it is determined that the playback chatter has occurred, and each time the chatter detection signal and the data related to the playback chatter frequency are transmitted to the rotation speed adjustment unit 5. Perform the process.
  • Fourier analysis frequency analysis
  • the stable rotation speed S S is a rotation speed corresponding to the k-th order stability pot in the stability limit diagram shown in FIG. 5 described above.
  • the spindle rotation speed By adjusting the spindle rotation speed to this stable rotation speed S S , the regenerative chatter There is a possibility that can be resolved.
  • the stable rotational speed S S obtained by Equation 5 is within the stable region. In this case, the chatter can be eliminated by changing the spindle rotation speed from S 0 to S S.
  • the playback chatter frequency ⁇ 0 is acquired from the chatter detecting unit 4.
  • the tool number currently being machined is acquired from the NC program execution unit 11, and then the data related to the number of tool blades corresponding to the tool number is stored in the tool data storage unit 15. Obtained by getting from.
  • step S2 the spindle speed and tool T that is currently running from the NC program execution unit 11, changing the spindle speed from the current rotation speed to the stable rotational speed S S, one blade An adjusted feed speed is calculated so that the hit cutting amount (feed amount) is not changed (step S2).
  • the current spindle rotational speed can also be obtained from a rotary encoder attached to the spindle motor (not shown).
  • a rotational speed command corresponding to the stable rotational speed S S calculated as described above is transmitted to the main spindle control unit 13 to change the main spindle rotational speed to the stable rotational speed S S and to adjust the feed speed.
  • a corresponding feed speed command is transmitted to the feed control unit 14 to change the relative feed speed between the tool T and the workpiece W (hereinafter simply referred to as “feed speed of the tool T”) to the adjusted feed speed. (Step S3).
  • the coefficient k may be an arbitrary integer, but in a state where chatter vibration does not occur, a cutting condition with higher cutting efficiency is set by increasing the rotational speed further than the current spindle rotational speed. If you want to set cutting conditions that extend the tool life by reducing the rotation speed from the current spindle rotation speed without causing chatter vibration, based on the current spindle rotation speed and chatter frequency Specifically, it is set to a value different from the coefficient k 0 calculated according to Equation 8 described later.
  • step S16 when the playback chatter is eliminated by the processing of steps S2 and S3, the process proceeds to step S16 described later.
  • the playback chatter is not eliminated, and the chatter detection signal is continuously input from the chatter detection unit 4.
  • the coefficient k 0 ′ is calculated based on the spindle rotational speed S 0 ′ [min ⁇ 1 ], the regenerative chatter frequency ⁇ 0 ′ [Hz], and the number N of blades of the tool according to the following formula 6. Is calculated (step S5).
  • k 0 ′ (60 ⁇ ⁇ 0 ′) / (N ⁇ S 0 ′)
  • k 0 ′ is an integer obtained by rounding down the decimal part.
  • the spindle rotational speed is set to increase at a predetermined change amount at predetermined time intervals.
  • An increase amount (adjustment amount) for increasing the feed rate is set so that the cutting amount (feed amount) per blade of the tool T is not changed in accordance with the increase in the spindle rotation speed (steps S6 and S7). The process proceeds to the next step S9.
  • the coefficient k 0 ′ calculated by the above equation 6 represents the order of the stability lobe (curved downward curve) in the stability limit diagram, and the spindle rotational speed S 0 ′ at that time is the order k 0 ′. Is within the range of the stability lobe.
  • the spindle rotational speed S 0 ′ is a rotational speed on the lower speed side than the stable pocket of the order k. Therefore, as described above, a predetermined time interval and The spindle rotation speed is increased by a predetermined change amount, and an increase amount for increasing the feed speed is set accordingly.
  • spindle speed S 0 at that time '( S 'in the case is equal to k (including the case k is greater than)
  • a setting is made to decrease the spindle rotational speed by a predetermined change amount at predetermined time intervals.
  • a reduction amount (adjustment amount) for decreasing the feed speed is set so that the cutting amount (feed amount) per blade of the tool T is not changed in accordance with the decrease in the spindle rotation speed (steps S6 and S8). The process proceeds to the next step S9.
  • the spindle rotational speed is set to decrease step by step at a predetermined time interval and with a predetermined amount of change so as to fall within.
  • step S9 the rotation speed adjustment unit 5 transmits a command related to the adjustment of the spindle rotation speed set in step S7 or step S8 to the spindle control unit 13, and the change amount in which the spindle rotation speed is set.
  • the feed rate adjustment command is transmitted to the feed control unit 14 to adjust the feed amount of the tool T by the set adjustment amount.
  • the rotational speed adjustment unit 5 calculates the coefficient k according to the following formula 7 based on the spindle rotational speed S i [min ⁇ 1 ] and the regenerative chatter frequency ⁇ i [Hz] after the adjustment process and the number N of blades of the tool. i is calculated (step S10), and it is confirmed whether or not the value of the calculated coefficient k i has changed (step S11). If the value of the coefficient k i does not change, whether or not the playback chatter has been eliminated. (Step S12), if the playback chatter is eliminated, the process proceeds to Step S16. If the playback chatter is not eliminated, Steps S9 to S11 are repeated.
  • k i (60 ⁇ ⁇ i ) / (N ⁇ S i )
  • i is an integer of 1 or more, and means the number of adjustments of the spindle rotation speed and feed speed.
  • k i is an integer obtained by rounding down decimal places.
  • step S11 when the value of the coefficient k i changes (step S11), the rotation speed adjustment unit 5 transmits a command signal for displaying that the value of the coefficient k i has changed to the display control unit 16 for display.
  • the device 17 is displayed that the value of the coefficient k i has changed, that is, that the chatter cannot be eliminated by adjusting the spindle rotational speed (step S13). Note that the processing in steps S10 and S11 is processing for detecting whether or not playback chatter cannot be eliminated.
  • the rotation speed adjustment unit 5 detects that the cutting vibration has disappeared from the NC program execution state in the NC program execution unit 11 and the vibration state detected by the chatter detection unit 4 or acts on the tool T.
  • a cutting stop signal is transmitted to the NC program execution unit 11 to stop the execution of the program, thereby stopping the rotation of the main shaft 24 and stopping the feed of the tool T to stop cutting.
  • a control signal for the retracting operation is appropriately transmitted from the rotation speed adjusting unit 5 to the feed control unit 14 to cause the tool T to execute the retracting operation, thereby stopping the cutting. good.
  • the rotation speed adjusting unit 5 repeats the processes of steps S1 to S15 until a process end signal is input, and ends the process when the process end signal is input (step S16).
  • the NC program is executed by the NC program execution unit 11 and vibrations generated in the tool T while the workpiece W is machined by the machine tool 20.
  • a signal detected by the acceleration sensor 2 and corresponding to the vibration is input from the acceleration sensor 2 to the chatter detection unit 4.
  • the chatter detection unit 4 analyzes the vibration signal continuously input at appropriate sampling intervals, calculates the vibration frequency and the magnitude of the tool T, and the calculated magnitude of the vibration exceeds a predetermined threshold value.
  • the chatter detection signal and the data related to the playback chatter frequency are transmitted from the chatter detection unit 4 to the rotation speed adjustment unit 5.
  • the rotational speed adjusting unit 5 receives the chatter frequency ⁇ 0 [Hz] at that time and the number N of blades of the tool T, and the above formula 5 stable rotational speed to calculate the S S, changing the spindle speed from the current rotation speed to the stable rotational speed S S, adjusted feed rate as the cutting amount (feeding amount) is not changed per blade according Is calculated.
  • the stable rotational speed S S is the estimated rotational speed corresponding to the k-th order stable pot in stability limit diagram, firstly, by changing the spindle speed to the stable rotational speed S S, it is elimination of regenerative chatter Tried.
  • changing the spindle speed to such a stable rotational speed S S as the feed amount per blade of the tool T does not change, because the feed speed of the tool T also adjusted by the tool T
  • the theoretical surface roughness of the workpiece W to be machined can be made constant, thereby preventing the machining accuracy from deteriorating by changing the spindle rotation speed.
  • the coefficient k 0 ′ is calculated according to Equation 6 above, and if the calculated coefficient k 0 ′ is equal to or greater than the coefficient k, it is determined that the target stable pocket is not exceeded. Therefore, the spindle rotational speed is increased stepwise at a predetermined time interval and with a predetermined amount of change, and the cutting amount (feed amount) per blade of the tool T corresponding to the increase in the spindle rotational speed. ) Is increased so that the feed rate of the tool T is increased.
  • the calculated coefficient k 0 ′ is a value smaller than the coefficient k, it is determined that the target stable pocket is exceeded, and therefore, at a predetermined time interval and a predetermined change amount, In addition, the spindle rotational speed is reduced, and the feed rate of the tool T is reduced so that the cutting amount (feed amount) per blade of the tool T is not changed in response to the decrease in the spindle rotational speed.
  • the relationship between the spindle rotational speed and the cutting depth of the tool is shown in the stability pocket in the stability limit diagram.
  • the transition state that is, the unstable region where the regenerative chatter occurs can be shifted to the stable region where the regenerative chatter does not occur, and thus the regenerative chatter of the tool can be eliminated (or suppressed).
  • the rotation speed adjustment unit 5 is configured to perform the processes of steps S10 and S11 as a process for detecting whether or not the playback chatter cannot be eliminated.
  • step S9 the spindle rotational speed adjustment command and the feed speed adjustment command are output, and instead of step S10, the playback chatter frequency output from the chatter detection unit 4 and the previous output are output in step S9.
  • step S11 it is determined whether or not the calculated difference value exceeds a predetermined reference value.
  • playback chatter can be eliminated by adjusting the spindle speed instead of step S14. After the process of displaying on the display device 17 to the effect that had, may be configured to proceed to step S14.
  • FIG. 12A is a diagram having the same contents as FIG. 10 described above, and FIG. 12B shows the regenerative chatter frequency in the spindle rotational speed region corresponding to each stability lobe shown in FIG. FIG.
  • the regenerative chatter phenomenon gradually increases the regenerative chatter frequency as the spindle rotation speed increases in the region corresponding to each stability lobe in the stability limit diagram. (Continuously increases), and when moving from the high-order stability lobe region to the low-order stability lobe region in the process of increasing the spindle rotation speed, in other words, straddling the stability pocket In some cases, the reproduction chatter frequency is rapidly reduced.
  • the difference value (change amount) between the playback chatter frequency output from the chatter detection unit 4 and the playback chatter frequency output last time. Is greater than the predetermined reference value, it is determined that the spindle rotational speed has fluctuated across the stable pocket, as shown by the behavior of S 0 ′ in the figure. In this case, the cutting depth of the current tool is determined. However, it may be determined that the relationship between the cutting depth of the tool and the spindle rotation speed cannot be shifted to the stable region by adjusting the spindle rotation speed because the limit cutting depth of the stable pocket is exceeded. it can.
  • the rotation speed adjustment unit 5 is configured to perform the processes of steps S2 to S6.
  • the present invention is not limited to this, and when the chatter detection signal is received in step S1, the step is performed.
  • the spindle rotational speed may be decreased at a predetermined time interval and a predetermined amount of change, and a setting process (step S8) for decreasing the feed speed of the tool T in accordance with this may be executed (step S8).
  • FIG. 11 Whether step S7 is executed or step S8 is executed can be arbitrarily set.
  • the coefficient k 0 represents the order of the stability lobe in the stability limit diagram.
  • the stability limit diagram regarding regenerative chatter has a tendency that when the order of the stability pocket is higher than a certain value, the limit cutting depth tends to increase as the spindle speed decreases. This is generally called a process damping region (see FIG. 11).
  • the spindle rotation speed and the feed speed of the tool T are set at a predetermined time interval and a predetermined change amount.
  • a process of decreasing in a stepwise manner, that is, guiding the spindle rotation speed into the process damping region is performed.
  • the spindle rotational speed and the feed speed of the tool T are set to predetermined time intervals in the subsequent processing. In addition, it is increased or decreased stepwise by a predetermined change amount. Thereby, the spindle rotational speed can be more effectively guided to the stable region (see FIG. 11).
  • the vibration of the tool T is detected by the acceleration sensor 2 provided on the spindle head 23.
  • the present invention is not limited to this, and the processing sound generated during processing is collected by a microphone.
  • the machining vibration may be detected.
  • chatter detection 4 it is determined that the playback chatter has occurred when the magnitude of vibration obtained by the FFT analysis exceeds a predetermined threshold.
  • the present invention is not limited to this.
  • the difference value of the vibration level (magnitude) detected at the sampling interval exceeds a predetermined threshold value, it may be determined that playback chatter has occurred.
  • the arithmetic processing device 3 of the spindle rotational speed adjusting device 1 is provided separately from the numerical control device 10, but is not limited to such a configuration, and the arithmetic processing device 3 is replaced by the numerical control device 10.
  • a built-in configuration may be used.

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  • Engineering & Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Mechanical Engineering (AREA)
  • Automatic Control Of Machine Tools (AREA)
  • Numerical Control (AREA)

Abstract

L'invention concerne un dispositif de réglage de la vitesse d'un arbre principal (1) comportant : une unité de détection de vibration (capteur d'accélération) (2) pour détecter la vibration d'un outil; une unité de détection de broutage (4) pour surveiller un signal de détection de l'unité de détection de vibration (2) afin de déterminer la présence ou l'absence de broutage régénératif; et une unité de réglage de la vitesse de rotation (5) qui, lors de la réception d'un signal de détection provenant de l'unité de détection de broutage (4), transmet à un dispositif de commande numérique (10) un signal de réglage de vitesse pour augmenter ou réduire la vitesse de l'arbre principal pendant un intervalle de temps prescrit et avec une ampleur de variation prescrite. Chaque fois que le signal de réglage de vitesse est transmis, l'unité de réglage de la vitesse de rotation (5) détecte si un broutage régénératif peut être résolu, et s'il a été détecté que le broutage régénératif ne peut pas être résolu, l'unité de réglage de la vitesse de rotation termine la coupe, termine le réglage de la vitesse de l'arbre principal et/ou annonce que le broutage régénératif ne peut pas être résolu.
PCT/JP2018/001000 2017-04-04 2018-01-16 Dispositif de commande de vitesse d'arbre principal WO2018185993A1 (fr)

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CN112395809A (zh) * 2020-11-20 2021-02-23 华中科技大学 一种加工零件表面振纹缺陷检测方法
CN116638124A (zh) * 2023-07-27 2023-08-25 深圳市欣茂鑫实业有限公司 一种用于一体式镜筒的加工控制系统及方法
TWI826688B (zh) * 2019-05-13 2023-12-21 日商迪思科股份有限公司 刀片裝卸輔助裝置

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JP2019072806A (ja) * 2017-10-17 2019-05-16 オムロン株式会社 切削加工装置
JP7022242B1 (ja) 2021-06-28 2022-02-17 Dmg森精機株式会社 工作機械および表示制御装置
JP6994596B1 (ja) 2021-06-28 2022-01-14 Dmg森精機株式会社 工作機械および表示制御装置
JP7192152B1 (ja) 2022-01-07 2022-12-19 Dmg森精機株式会社 表示制御装置および工作機械
JP7159494B1 (ja) 2022-01-07 2022-10-24 Dmg森精機株式会社 表示制御装置および工作機械

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TWI826688B (zh) * 2019-05-13 2023-12-21 日商迪思科股份有限公司 刀片裝卸輔助裝置
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CN112395809B (zh) * 2020-11-20 2023-12-19 华中科技大学 一种加工零件表面振纹缺陷检测方法
CN116638124A (zh) * 2023-07-27 2023-08-25 深圳市欣茂鑫实业有限公司 一种用于一体式镜筒的加工控制系统及方法
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