Machine tool control device and machine tool control program

Abstract

The purpose of the present invention is to suppress wasteful power consumption during a tool change. This machine tool control device controls a machine tool. The machine tool comprises a spindle, and a tool attached to the spindle is changed by means of a changing device. The machine tool control device is provided with an execution unit, a calculation unit, and a restriction unit. Before and / or after a tool change, the execution unit causes the simultaneous execution of: a speed change operation for changing the rotation speed of the spindle to a target speed; and a feed operation for causing the position of the spindle relative to a prescribed object to be moved to target coordinates. The calculation unit calculates the completion time of the speed change operation and the completion time of the feed operation. The restriction unit performs restriction control for restricting the absolute value of the acceleration in a previously completed operation that has the earliest completion time in the calculations among the speed change operation and the feed operation. Accordingly, the completion time of the previously completed operation is delayed in comparison to that when the restriction control is not performed.

Description

Machine tool control device and machine tool control program

[0001] The present disclosure relates to an apparatus for controlling a machine tool.

[0002] Some machine tools are equipped with a spindle, and a tool attached to the spindle is automatically changed by a changer.

[0003] Japanese Patent Application Laid-Open No. 2018-039068

[0004] Before a tool is replaced by a tool changer, the control device for such a machine tool must decelerate the rotational speed of the spindle to a target speed such as zero and move the spindle to a target coordinate such as a tool change start coordinate so that the tool can be replaced. After a tool is replaced by a tool changer, the control device must accelerate the rotational speed of the spindle to a target speed such as a machining speed and move the spindle to a target coordinate such as a machining start coordinate so that the workpiece can be machined. In these cases, in order to shorten the cycle time of machining by the machine tool, a speed-changing operation for changing the rotational speed of the spindle to the target speed and a feeding operation for moving the spindle to the target coordinate may be simultaneously performed.

[0005] The present inventors have noticed that in such a case, the following problem may occur: The time at which the speed change operation is completed may differ greatly from the time at which the forward operation is completed. In this case, the speed change operation or the forward operation that is completed earlier may consume more power than necessary.

[0006] Specifically, for example, if the machining speed is not very high after a tool change, and the completion time of the speed change operation is much earlier than the completion time of the feed operation, the rotational speed of the spindle will reach the machining speed long before the spindle reaches the machining start coordinates. However, it is sufficient for the rotational speed of the spindle to reach the machining speed by the time the spindle reaches the machining start coordinates. As a result, the spindle is not only unnecessarily accelerated, but also rotated at the machining speed for an unnecessarily long time, resulting in unnecessarily large power consumption during the speed change operation. Furthermore, this power consumption generates unnecessary heat in the machine tool, which may lead to overheating and reduced machining accuracy.

[0007] Conversely, if the machining speed is high and the completion time of the speed change operation is much later than the completion time of the feed operation, a large amount of power will be wasted in the feed operation.

[0008] The present disclosure has been made in consideration of the above circumstances, and aims to reduce unnecessary power consumption when changing tools.

[0009] The first disclosure is a machine tool control device that controls a machine tool that has a spindle and in which tools attached to the spindle are exchanged by an exchange device, and that includes: an execution unit that simultaneously executes a speed change operation that changes the rotational speed of the spindle to a target speed and a feed operation that moves the relative position of the spindle with respect to a specified object to a target coordinate at least either before or after tool exchange; a calculation unit that calculates the completion time of the speed change operation and the completion time of the feed operation; and a suppression unit that performs suppression control to suppress the absolute value of acceleration in the earlier-completed operation, whichever of the speed change operation and the feed operation has an earlier completion time in the calculation, thereby delaying the completion time of the earlier-completed operation compared to when the suppression control is not performed.

[0010] The second disclosure is a machine tool control program that causes a computer to function as a device for controlling a machine tool that has a spindle and in which tools attached to the spindle are exchanged by an exchange device, and causes the computer to function as: an execution unit that simultaneously executes a speed change operation that changes the rotational speed of the spindle to a target speed and a feed operation that moves the relative position of the spindle with respect to a specified object to a target coordinate at least either before or after a tool exchange; a calculation unit that calculates the completion time of the speed change operation and the completion time of the feed operation; and a suppression unit that performs suppression control to suppress the absolute value of acceleration in the earlier-completed operation, whichever of the speed change operation and the feed operation has an earlier completion time in the calculation, thereby delaying the completion time of the earlier-completed operation compared to when the suppression control is not performed.

[0011] FIG. 1 is a block diagram showing a numerical control device and a machine tool of a first embodiment. FIG. 2 is a front view showing a spindle disposed at a predetermined coordinate before tool change. FIG. 3 is a front view showing a spindle disposed at an exchange start coordinate. FIG. 4 is a front view showing a spindle disposed above the exchange start coordinate. FIG. 5 is a front view showing a spindle disposed at an exchange end coordinate. FIG. 6 is a front view showing a spindle disposed at a machining start coordinate. FIG. 7 is a graph showing the relationship between a speed change amount and a speed change time in a speed change operation. FIG. 8 is a graph showing the relationship between a feed amount and a feed time in a feed operation. FIG. 9 is a graph showing a case where a deceleration operation is a first-completed operation before tool change. FIG. 10 is a graph showing a case where an upper feed operation is a first-completed operation before tool change. FIG. 11 is a graph showing a case where an acceleration operation is a first-completed operation after tool change. FIG. 12 is a graph showing a case where a lower feed operation is a first-completed operation after tool change. FIG. 13 is a flowchart showing a flow of control by a numerical control device.

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the following embodiments and can be appropriately modified and implemented within the scope of the present disclosure.

[0013] 1, a numerical control device 50 is installed relative to a machine tool 120 and controls the machine tool 120. The numerical control device 50 may be read as a "machine tool control device." Hereinafter, three predetermined directions that are orthogonal to one another will be referred to as the "X direction," "Y direction," and "Z direction." In this embodiment, the X direction and the Y direction are horizontal directions, and the Z direction is the up-down direction.

[0014] As shown in FIG. 1 , the machine tool 120 includes a spindle 80 , a spindle drive unit 70 , a Z-direction feed unit 60 , an X-direction feed unit 90 , and a Y-direction feed unit 100 .

[0015] A tool 85 is attached to the lower end of the spindle 80. The spindle 80 machines the workpiece W with the tool 85. The spindle drive device 70 has a spindle amplifier 73 and a spindle motor 74. The spindle motor 74 rotates the spindle 80. The spindle amplifier 73 controls the spindle motor 74 based on commands from the execution unit 21 of the numerical control device 50. Hereinafter, the rotation speed of the spindle 80 will be referred to as the "spindle rotation speed Sp."

[0016] The Z-direction feed device 60 has a Z-axis amplifier 63, a Z-axis motor 64, a Z-direction feed shaft 65, and a movable member 66. The movable member 66 holds a spindle motor 74 and a spindle 80. The Z-direction feed shaft 65 extends in the Z direction and is threadedly engaged with the movable member 66. The Z-axis motor 64 rotates the Z-direction feed shaft 65. The Z-axis amplifier 63 controls the Z-axis motor 64 based on commands from the execution unit 21 of the numerical control device 50. When the Z-direction feed shaft 65 rotates in one direction, the movable member 66 moves upward in one direction in the Z direction, and when the Z-direction feed shaft 65 rotates in the other direction, the movable member 66 moves downward in the other direction in the Z direction.

[0017] The X-direction feed device 90 has an X-axis amplifier 93, an X-axis motor 94, an X-direction feed shaft 95, and a table 96. The table 96 is configured to be able to hold a workpiece W. The X-direction feed shaft 95 extends in the X direction and is screwed to the table 96. The X-axis motor 94 rotates the X-direction feed shaft 95. The X-axis amplifier 93 controls the X-axis motor 94 based on a command from the execution unit 21 of the numerical control device 50. When the X-direction feed shaft 95 rotates in one direction, the table 96 moves in one direction in the X direction, and when the X-direction feed shaft 95 rotates in the other direction, the table 96 moves in the other direction in the X direction.

[0018] The Y-direction feed device 100 includes a Y-axis amplifier 103, a Y-axis motor 104, a Y-direction feed shaft 105, and a saddle 106. The saddle 106 is attached to the X-axis motor 94. The Y-direction feed shaft 105 extends in the Y direction and is threadedly engaged with the saddle 106. The Y-axis motor 104 rotates the Y-direction feed shaft 105. The Y-axis amplifier 103 controls the Y-axis motor 104 based on commands from the execution unit 21 of the numerical control device 50. When the Y-direction feed shaft 105 rotates in one direction, the table 96, which is engaged with the saddle 106 via the X-axis motor 94 and the like, moves in one direction in the Y direction together with the saddle 106. When the Y-direction feed shaft 105 rotates in the other direction, the table 96, together with the saddle 106, moves in the other direction in the Y direction.

[0019] Hereinafter, the relative position of the spindle 80 with respect to a predetermined object will be referred to as the "spindle position Zp." Specifically, before the tool change, the object is the tool change device 200, and after the tool change, the object is the workpiece W. In this embodiment, both before and after the tool change, the spindle position Zp is changed by moving the spindle 80 in the Z direction by the Z-direction feed device 60.

[0020] 1, an exchange device 200 is installed for machine tool 120. Exchange device 200 exchanges tool 85 attached to spindle 80 with another tool 85.

[0021] Hereinafter, the operation of changing the spindle rotation speed Sp to the target speed will be referred to as a “speed change operation.” The “speed change operation” includes a “deceleration operation” performed before tool change and an “acceleration operation” performed after tool change.

[0022] 10, the "deceleration operation" is an operation for decelerating the spindle rotation speed Sp from a predetermined speed SpO before the start of the deceleration operation to zero as a target speed. Hereinafter, the time required from the start to the completion of the deceleration operation will be referred to as the "deceleration time TsB."

[0023] 12, the "acceleration operation" is an operation for accelerating the spindle rotation speed Sp from zero immediately after tool change to a machining speed SpA as a target speed. Hereinafter, the time required from the start to the completion of the acceleration operation will be referred to as the "acceleration time TsA."

[0024] In the following description, the "deceleration time TsB" and the "acceleration time TsA" will be collectively referred to as the "gear-shifting time Ts." In other words, the "gear-shifting time Ts" is the time required from the start to the completion of a gear-shifting operation.

[0025] Hereinafter, the operation for changing the spindle position Zp to each "target coordinate" before and after tool change will be simply referred to as "feed operation." "Feed operation" includes an "upper feed operation" performed before tool change and a "lower feed operation" performed after tool change. In "upper feed operation," the "target coordinate" is the "exchange start coordinate ZpB." On the other hand, in "lower feed operation," the "target coordinate" is the "machining start coordinate ZpA."

[0026] More specifically, the "top feed operation" is an operation for raising the spindle position Zp from the predetermined coordinate ZpO shown in FIG. 2 to the exchange start coordinate ZpB shown in FIG. 3. After the "top feed operation," the spindle position Zp is further raised from the exchange start coordinate ZpB shown in FIG. 3 to the exchange start coordinate ZpB shown in FIG. 4, whereby the tool 85 attached to the spindle 80 is removed by the exchange device 200. Thereafter, the exchange device 200 rotates, whereby the tool 85 to be next attached to the spindle 80 is positioned directly below the spindle 80. From this state, as shown in FIG. 5, the spindle 80 is lowered to the exchange end coordinate ZpB, which is the same as the exchange start coordinate ZpB, whereby the tool 85 is attached to the spindle 80. Hereinafter, as shown in FIG. 9, the time required from the start to the completion of the top feed operation before tool exchange is referred to as the "top feed time TzB."

[0027] On the other hand, the "bottom feed operation" is an operation of lowering the spindle position Zp from an exchange end coordinate that is the same as the exchange start coordinate ZpB shown in Fig. 5 to a machining start coordinate ZpA shown in Fig. 6. After the "bottom feed operation", the spindle position Zp is further lowered from the machining start coordinate ZpA shown in Fig. 6, thereby starting machining of the workpiece W with the tool 85. Hereinafter, as shown in Fig. 11, the time required from the start to the completion of the bottom feed operation after tool exchange is referred to as the "bottom feed time TzA".

[0028] In the following description, the "top feed time TzB" and the "bottom feed time TzA" will be collectively referred to as the "feed time Tz." In other words, the "feed time Tz" is the time required from the start to the completion of the feed operation.

[0029] The numerical control device 50 shown in Fig. 1 is mainly composed of a computer into which a numerical control program has been loaded. In other words, the numerical control program causes the computer to function as the numerical control device 50. In other words, the numerical control device is realized by the cooperation of the computer and the numerical control program. The computer includes a CPU, ROM, RAM, etc. The numerical control program may also be read as a "machine tool control program."

[0030] 1, the numerical control device 50 includes an execution unit 21, an analysis unit 25, a calculation unit 24, a determination unit 23, a suppression unit 22, a memory 35, a feedback unit 31, and a correction unit 32. The execution unit 21, the analysis unit 25, the calculation unit 24, the determination unit 23, the suppression unit 22, and the correction unit 32 are each configured to be able to access the memory 35.

[0031] By reading the machining program 10, the execution unit 21 executes control of the machine tool 120 in accordance with the machining program 10. In this control, the execution unit 21 causes the machine tool 120 to simultaneously execute a speed change operation and a feed operation before and after a tool change in order to reduce the cycle time of machining by the machine tool 120. In other words, before a tool change, the execution unit 21 causes the machine tool 120 to simultaneously execute a deceleration operation and an upper feed operation. On the other hand, after a tool change, the execution unit 21 causes the machine tool 120 to simultaneously execute an acceleration operation and a lower feed operation.

[0032] The analysis unit 25 reads the machining program 10. The analysis unit 25 determines whether or not a speed change operation and a feed operation will be performed simultaneously in the future based on the analysis of the machining program 10. As a result, the analysis unit 25 determines that the simultaneous execution will be performed both before and after the tool change.

[0033] The calculation unit 24 calculates the speed change time Ts and the feed time Tz on the condition that the analysis unit 25 determines that the simultaneous execution will be performed. In other words, it calculates the completion time ts of the speed change operation and the completion time tz of the feed operation. Specifically, before the tool change, the calculation unit 24 calculates the deceleration time TsB and the top feed time TzB shown in FIG. 9. In other words, it calculates the completion time tsB of the deceleration operation and the completion time tzB of the top feed operation. On the other hand, after the tool change, it calculates the acceleration time TsA and the bottom feed time TzA shown in FIG. 11. In other words, it calculates the completion time tsA of the acceleration operation and the completion time tzA of the bottom feed operation.

[0034] Specifically, the calculation unit 24 shown in Fig. 1 calculates the speed change time Ts based on the formula, for example, "Ts = As(n,n)) x Ys(n) x αs(n) x βs." Hereinafter, the amount of change in the spindle rotation speed Sp during the speed change operation will be referred to as the "speed change amount ΔSp." In the above formula, "As(n,n)" is a representative value determined for each type of tool 85 and each speed change amount ΔSp. In the above formula, "Ys(n)" is a correction coefficient that takes into account the fact that the speed change time Ts changes depending on the output of the spindle motor 74.

[0035] In the above equation, "αs(n)" is a correction coefficient for the speed change time Ts based on the difference between the reference tool inertia and the actual tool inertia. Therefore, "αs(n)" differs depending on the type of tool 85. Specifically, the greater the tool inertia, the greater "αs(n)" becomes, and the longer the speed change time Ts becomes. "βs" is a correction coefficient for minimizing the error between the representative value "As(n,n)" and the actual measured value due to individual differences when actually performing a speed change operation.

[0036] These values, that is, the values ​​for "Az(n,n)", "Yz(n)", "αs(n)", and "βs", are each stored in memory 35. Although these values ​​are each discrete, intermediate values ​​are calculated using a function that connects adjacent values.

[0037] For example, if the tool 85 is the "sixth tool" and the speed change amount ΔSp is "2000 rpm," then "As(6th, 2000 rpm)," a representative value corresponding to the "sixth tool" and "2000 rpm," is used as "As(n, n)" in the above formula. Furthermore, "αs(6th)," a correction coefficient corresponding to the "sixth tool," is used as "αs(n)" in the above formula. Furthermore, if the output of the spindle motor 74 is "90%,," then "Yz(90%)," a correction coefficient corresponding to "90%, is used as "Ys(n)" in the above formula. Therefore, in the above cases, the speed change time Ts can be calculated by the formula: "Ts = As(6th, 2000 rpm) × Yz(90%) × αs(6th) × βs."

[0038] According to this formula, the larger the speed change amount ΔSp, the longer the speed change time Ts, as shown in Figure 7. Therefore, when the output of the spindle motor 74 is at each value, for example, if the speed change amount ΔSp is a "predetermined speed change amount ΔSpQ," the "predetermined speed change time TsQ" corresponding to that "predetermined speed change amount ΔSpQ" becomes the speed change time Ts.

[0039] On the other hand, the calculation unit 24 shown in FIG. 1 calculates the feed time Tz based on the formula, for example, "Tz = Az(n) × Yz(n) × βz." Hereinafter, the amount of change in the spindle position Zp during the feed operation is referred to as the "feed amount ΔZp." In the above formula, "Az(n)" is a representative value determined for each feed amount ΔZp. "Yz(n)" in the above formula is a correction coefficient for the feed time Tz, which varies depending on the output of the Z-axis motor 64. "βz" in the above formula is a correction coefficient for minimizing the error between the representative value "Az(n)" and the actual measured value due to individual differences during the actual feed operation. These values, i.e., the values ​​for "Az(n)," "Yz(n)," and "βz," are stored in the memory 35.

[0040] For example, if the feed amount ΔZp is "150 mm," then the representative value "Az(150 mm)" corresponding to this "150 mm" is used as "Az(n)." For example, if the output of the Z-axis motor 64 is "80%, then the correction coefficient "Yz(80%)" corresponding to this "80%" is used as "Yz(n)." Therefore, in the above cases, the feed time Tz can be calculated using the formula "Tz = Az(150 mm) × Yz(80%) × βz."

[0041] According to this formula, the larger the feed amount ΔZp, the longer the feed time Tz, as shown in Fig. 8. Therefore, when the output of the spindle motor 74 is at each value, for example, if the feed amount ΔZp is a "predetermined feed amount ΔZpQ," the "predetermined feed time TzQ" corresponding to that "predetermined feed amount ΔZpQ" becomes the feed time Tz.

[0042] The determination unit 23 shown in FIG. 1 determines whether suppression is necessary based on the shifting time Ts and the forwarding time Tz calculated by the calculation unit 24. In other words, the determination unit 23 determines whether suppression is necessary based on the completion time of the shifting operation and the completion time of the forwarding operation. Specifically, for example, the determination unit 23 determines that suppression is unnecessary if the ratio between the calculated shifting time Ts and the calculated forwarding time Tz is within a predetermined range, and determines that suppression is necessary if the ratio is outside the range. More specifically, for example, the determination unit 23 determines that suppression is unnecessary if the ratio is within a range of 4 / 5 to 5 / 4, that is, 80 to 125%, and determines that suppression is necessary otherwise. Furthermore, for example, if the absolute value of the difference between the calculated shifting time Ts and the calculated forwarding time Tz is greater than a predetermined value, the determination unit 23 determines that suppression is necessary, and if it is smaller, the determination unit 23 determines that suppression is unnecessary.

[0043] The suppression unit 22 shown in FIG. 1 does nothing if the determination unit 23 determines that suppression is not necessary. On the other hand, if the determination unit 23 determines that suppression is necessary, the suppression unit 22 performs suppression control C by influencing the execution unit 21. Hereinafter, the speed change operation or the feed operation whose completion time is earlier in the calculation by the calculation unit 24 is referred to as the "early completion operation," and the later is referred to as the "later completion operation." The suppression control C is a control that suppresses the absolute value of the acceleration in the early completion operation. By performing this suppression control, the suppression unit 22 delays the completion time of the early completion operation within a range that does not make it later than the completion time of the later completion operation. More specifically, the process is described below, divided into before and after tool change.

[0044] First, a case where it is determined that suppression is necessary before tool change will be described. In this case, as shown by the solid line in FIG. 9 , if the calculated completion time tsB of the deceleration operation is earlier than the calculated completion time tzB of the upper feed operation, the deceleration operation will be the earlier completion operation and the upper feed operation will be the later completion operation. In this case, the suppression unit 22 suppresses deceleration in the deceleration operation by suppression control C, as shown by the dashed line in FIG. 9 . This delays the completion time tsB of the deceleration operation compared to before suppression control C is performed, i.e., compared to when suppression control C is not performed. However, this suppression control C is performed within a range in which the completion time tsB of the deceleration operation is not later than the completion time tzB of the upper feed operation.

[0045] Specifically, for example, before suppression control C is performed, the output of the spindle motor 74 and the output of the Z-axis motor 64 are both 100%. In this case, for example, if the output of the spindle motor 74 is suppressed to 55% as shown in Fig. 7, and the speed change time Ts becomes equal to the feed time Tz, the output of the spindle motor 74 is suppressed within a range not falling below 55%. As a result, as shown in Fig. 9, the deceleration time TsB is lengthened within a range not exceeding the upper feed time TzB.

[0046] On the other hand, as shown by the solid line in FIG. 10 , if the calculated completion time tsB of the deceleration operation is later than the calculated completion time tzB of the upper feed operation, the deceleration operation will be the later completion operation and the upper feed operation will be the earlier completion operation. In this case, the suppression unit 22 suppresses at least the acceleration of the upper feed operation using suppression control C, as shown by the dashed line in FIG. 10 . This suppresses the rising speed of the upper feed operation. This makes the completion time tzB of the upper feed operation later than before suppression control C was performed, i.e., compared to when suppression control C was not performed. However, this suppression control C is performed within a range where the completion time tzB of the upper feed operation is not later than the completion time tsB of the deceleration operation. Specifically, the completion time tzB of the upper feed operation is set to be approximately the same as the completion time tsB of the deceleration operation.

[0047] Next, a case where it is determined that suppression is necessary after a tool change will be described. In this case, as shown by the solid line in FIG. 11 , if the calculated completion time tsA of the acceleration operation is earlier than the calculated completion time tzA of the lower feed operation, the acceleration operation will be the earlier completion operation and the lower feed operation will be the later completion operation. In this case, the suppression unit 22 suppresses the acceleration of the acceleration operation by suppression control C, as shown by the dashed line in FIG. 11 . This delays the completion time tsA of the acceleration operation compared to before suppression control C is performed, i.e., compared to when suppression control C is not performed. However, this suppression control C is performed within a range in which the completion time tsA of the acceleration operation is not later than the completion time tzA of the lower feed operation.

[0048] On the other hand, as shown by the solid line in FIG. 12 , if the calculated completion time tsA of the acceleration operation is later than the calculated completion time tzA of the lowering operation, the acceleration operation will be the later completion operation and the lowering operation will be the earlier completion operation. In this case, the suppression unit 22 suppresses acceleration and deceleration in the lowering operation using suppression control C, as shown by the dashed line in FIG. 12 . This suppresses the descent speed in the lowering operation. This makes the completion time tzA of the lowering operation later than before suppression control C is performed, i.e., compared to when suppression control C is not performed. However, this suppression control C is performed within a range where the completion time tzA of the lowering operation is not later than the completion time tsA of the acceleration operation. Specifically, the completion time tzA of the lowering operation is set to be approximately the same as the completion time tsA of the acceleration operation.

[0049] 1 delays the completion time of the earlier-completion action to a degree that does not make it later than the completion time of the later-completion action by performing the suppression control C. Note that the completion time of the earlier-completion action after the suppression control C is also calculated using the same calculation method as in the case of the calculation unit 24.

[0050] The feedback determination unit 31 is configured to be able to communicate with each of the spindle amplifier 73, the Z-axis amplifier 63, the X-axis amplifier 93, and the Y-axis amplifier 103. From the communications with these amplifiers, the feedback determination unit 31 determines whether the completion time of the earlier-completion operation is later than the completion time of the later-completion operation, in other words, whether a problem has occurred.

[0051] The correction unit 32 does not perform any particular action when the feedback determination unit 31 determines that no problem has occurred. On the other hand, when the feedback determination unit 31 determines that a problem has occurred, the correction unit 32 performs a correction to suppress the suppression control C. Specifically, for example, the correction unit 32 corrects one or more of the aforementioned "As(n,n)," "Ys(n)," "αs(n)," "βs," "Az(n)," "Yz(n)," and "βz" stored in memory. This correction prevents the completion time of the earlier-completion action from being later than the completion time of the later-completion action.

[0052] Next, the control flow shown above will be explained with reference to Fig. 13. Note that in the following, the "S" before the numbers stands for "step."

[0053] First, in S1, the execution unit 21 reads the machining program 10 and executes the machining program 10. Next, in S2, the analysis unit 25 reads the machining program 10 and determines, based on an analysis of the machining program 10, whether or not a speed change operation and a feed operation will be performed simultaneously in the future. If a negative determination is made in S2, S2 is repeated, for example, at predetermined intervals. On the other hand, if a positive determination is made in S2, the process proceeds to S3.

[0054] In S3, the calculation unit 24 calculates the speed change time Ts and the feed time Tz. In the following S4, the determination unit 23 determines whether the speed change time Ts is sufficiently shorter than the feed time Tz. If the determination is affirmative, in S5, the suppression unit 22 suppresses the absolute value of the acceleration during the speed change operation using suppression control C. That is, if the tool change is before, the deceleration during the deceleration operation is suppressed, and if the tool change is after, the acceleration during the acceleration operation is suppressed. Then, the process proceeds to S8.

[0055] On the other hand, if a negative determination is made in S4, the process proceeds to S6. In S6, the determination unit 23 determines whether the speed change time Ts is sufficiently longer than the feed time Tz. If a positive determination is made, the suppression unit 22 suppresses the absolute value of the acceleration in the feed operation using suppression control C in S7. That is, if the tool change is before, at least the acceleration in the upper feed operation is suppressed, and if the tool change is after, the acceleration / deceleration in the lower feed operation is suppressed. Then, the process proceeds to S8. On the other hand, if a negative determination is made in S6, the process skips S7 and proceeds directly to S8.

[0056] In S8, the execution unit 21 executes the speed change operation and the feed operation simultaneously under the set conditions.

[0057] According to this embodiment, the following effects can be obtained.

[0058] The execution unit 21 shown in FIG. 1 simultaneously executes a speed change operation and a feed operation before and after a tool change. The calculation unit 24 calculates the completion time of the speed change operation and the completion time of the feed operation. The suppression unit 22 performs suppression control C to delay the completion time of the prior completion operation compared to when suppression control C is not performed. As a result, unnecessary power consumption during tool change can be suppressed. This suppresses unnecessary heat generation in the machine tool, thereby preventing overheating and a decrease in machining accuracy.

[0059] Specifically, if the calculation by the calculation unit 24 shows that the completion time of the speed change operation is earlier than the completion time of the feed operation, the suppression unit 22 suppresses the absolute value of the acceleration in the speed change operation by suppression control C. That is, before the tool change, deceleration in the deceleration operation is suppressed as shown in Fig. 9. On the other hand, after the tool change, acceleration in the acceleration operation is suppressed as shown in Fig. 11. As a result, the output of the spindle motor 74 can be suppressed, and power consumption can be reduced.

[0060] On the other hand, if the calculation by the calculation unit 24 shown in FIG. 1 indicates that the completion time of the speed change operation is later than the completion time of the feed operation, the suppression unit 22 suppresses the absolute value of the acceleration in the feed operation through suppression control C. That is, before the tool change, as shown in FIG. 10, at least the acceleration in the upward feed operation is suppressed. This suppresses the ascent speed of the spindle 80. On the other hand, after the tool change, as shown in FIG. 12, the acceleration and deceleration in the downward feed operation are suppressed, thereby suppressing the descent speed of the spindle 80. This suppresses the output of the Z-axis motor 64, thereby reducing power consumption.

[0061] 9 to 12, the suppression unit 22 delays the completion time of the earlier-completion operation to a degree that does not make it later than the completion time of the later-completion operation. Therefore, the completion time of the entire operation, including the speed change operation and the feed operation, does not change. Therefore, power consumption can be suppressed without lengthening the cycle time of the machining by the machine tool.

[0062] 1 performs a correction to suppress suppression control C when the completion time of the earlier-completion motion becomes later than the completion time of the later-completion motion due to suppression control C. This prevents the completion time of the earlier-completion motion from becoming later than the completion time of the later-completion motion. Therefore, it is possible to quickly return to a state in which the completion time of the earlier-completion motion is before the completion time of the later-completion motion.

[0063] The analysis unit 25 determines whether the speed change operation and the feed operation will be performed simultaneously based on the analysis of the machining program. The calculation unit 24 calculates the completion time of the speed change operation and the completion time of the feed operation on the condition that it is determined that the simultaneous execution will be performed. Therefore, based on the analysis of the machining program, it is possible to efficiently determine the timing at which the simultaneous execution will be performed and to calculate the completion time of the speed change operation and the completion time of the feed operation at that timing.

[0064] The determination unit 23 determines whether suppression control is necessary based on the completion time of the speed change operation calculated by the calculation unit 24 and the completion time of the feed operation calculated by the calculation unit 24. The suppression unit 22 performs suppression control C on the condition that it is determined that suppression control is necessary. Therefore, when the difference between the speed change time Ts and the feed time Tz is not so large, the calculation load on the numerical control device 50 can be reduced by not performing suppression control C.

[0065] The above-described embodiment can be modified, for example, as follows. The execution unit 21 shown in Fig. 1 may simultaneously execute the speed change operation and the feed operation only either before or after the tool change. In this case, it is sufficient for the calculation unit 24 to calculate the speed change time Ts and the feed time Tz for only that one of the periods, and for the suppression unit 22 to perform the suppression control C as needed.

[0066] The feeding operation may include, in addition to the operation of feeding the spindle 80 in the Z direction by the Z direction feed device 60, an operation of feeding the workpiece W in the X direction by the X direction feed device 90, and an operation of feeding the workpiece W in the Y direction by the Y direction feed device 100. In other words, the suppression control C may further suppress the absolute value of the acceleration in the operation of feeding the workpiece W in the X direction or the Y direction.

[0067] The Z direction, i.e., the direction in which the spindle 80 is fed, may be a direction other than the vertical direction. Furthermore, the X direction and the Y direction, i.e., the direction in which the workpiece W is fed, may be a direction other than the horizontal direction.

[0068] According to the above embodiment, the machine tool control device (50) shown in Supplementary Notes 1 to 9 and the machine tool control program shown in Supplementary Note 10 can be realized.

[0069] [Supplementary Note 1] A machine tool control device (50) for controlling a machine tool (120) that has a spindle (80) and in which a tool (85) attached to the spindle (80) is exchanged by an exchange device (200), the machine tool control device (50) comprising: an execution unit (21) that simultaneously executes a speed change operation that changes the rotational speed (Sp) of the spindle (80) to a target speed and a feed operation that moves a relative position (Zp) of the spindle with respect to a predetermined object to a target coordinate, at least either before or after a tool exchange; a calculation unit (24) that calculates a completion time of the speed change operation and a completion time of the feed operation; and a suppression unit (22) that performs suppression control (C) that suppresses an absolute value of acceleration in the earlier-completion operation, which is the speed change operation or the feed operation that has an earlier completion time in the calculation, thereby delaying the completion time of the earlier-completion operation compared to a case in which the suppression control (C) is not performed.

[0070] [Appendix 2] The machine tool control device (50) according to Appendix 1, wherein the suppression unit (22) delays the completion time of the earlier-completion operation by the suppression control within a range that does not delay the completion time of the later-completion operation, whichever of the speed change operation and the feed operation has the later completion time in the calculation.

[0071] [Appendix 3] The machine tool control device (50) according to Appendix 2, further comprising a correction unit that, when the suppression control (C) causes the completion time of the earlier-completion operation to be later than the completion time of the later-completion operation, performs a correction to suppress the suppression control (C) so that the completion time of the earlier-completion operation is not later than the completion time of the later-completion operation.

[0072] [Supplementary Note 4] The machine tool control device (50) according to any one of Supplementary Notes 1 to 3, wherein the execution unit (21) controls the machine tool (120) based on a machining program (10), and the machine tool control device (50) includes an analysis unit (25) that determines whether or not the speed change operation and the feed operation are to be performed simultaneously based on an analysis of the machining program (10), and the calculation unit (24) performs the calculation on the condition that it is determined that the simultaneous execution will be performed.

[0073] [Supplementary Note 5] The machine tool control device (50) according to any one of Supplementary Notes 1 to 4, further comprising a determination unit (23) that determines whether suppression control is necessary based on the completion time of the speed change operation in the calculation and the completion time of the feed operation in the calculation, and the suppression unit (22) performs the suppression control (C) on the condition that it is determined that the suppression control is necessary.

[0074] [Supplementary Note 6] The machine tool control device (50) according to any one of Supplementary Notes 1 to 5, wherein, when the calculation shows that the completion time of the speed change operation is earlier than the completion time of the feed operation, the suppression unit (22) suppresses an absolute value of the acceleration in the speed change operation by the suppression control (C).

[0075] [Supplementary Note 7] The machine tool control device (50) according to any one of Supplementary Notes 1 to 6, wherein, when the calculation shows that the completion time of the speed change operation is later than the completion time of the feed operation, the suppression unit (22) suppresses an absolute value of the acceleration in the feed operation by the suppression control (C).

[0076] [Supplementary Note 8] The machine tool control device according to any one of Supplementary Notes 1 to 7, wherein the execution unit (21) executes, as the speed change operation, an operation of decelerating the rotation speed (Sp) of the spindle (80) to zero as the target speed before the tool change, and executes, as the feed operation, an operation of moving the relative position (Zp) to an exchange start coordinate (ZpB) as the target coordinate.

[0077] [Supplementary Note 9] The machine tool control device according to any one of claims 1 to 8, wherein after the tool change, the execution unit (21) executes, as the speed change operation, an operation of accelerating the rotation speed (Sp) of the spindle (80) to a machining speed as the target speed, and executes, as the feed operation, an operation of moving the relative position (Zp) to a machining start coordinate (ZpA) as the target coordinate.

[0078] [Supplementary Note 10] A machine tool control program that causes a computer to function as a device for controlling a machine tool (120) that has a spindle (80) and in which a tool (85) attached to the spindle (80) is exchanged by an exchange device (200), the machine tool control program causing the computer to function as: an execution unit (21) that simultaneously executes a speed change operation that changes the rotational speed (Sp) of the spindle (80) to a target speed and a feed operation that moves a relative position (Zp) of the spindle with respect to a predetermined object to a target coordinate, at least either before or after tool exchange; a calculation unit (24) that calculates the completion time of the speed change operation and the completion time of the feed operation; and a suppression unit (22) that performs suppression control (C) that suppresses the absolute value of acceleration in the earlier-completion operation, whichever of the speed change operation and the feed operation has an earlier completion time in the calculation, thereby delaying the completion time of the earlier-completion operation compared to a case in which the suppression control (C) is not performed.

[0079] 10 Machining program 21 Execution unit 22 Suppression unit 23 Determination unit 24 Calculation unit 25 Analysis unit 50 Numerical control device (machine tool control device) 120 Machine tool 200 Exchange device C Suppression control Sp Spindle rotation speed (rotation speed of spindle) Zp Spindle position (relative position of spindle with respect to a predetermined object) ZpA Machining start coordinate ZpB Exchange start coordinate

Claims

1. A machine tool control device for controlling a machine tool having a spindle and in which a tool attached to the spindle is replaced by a replacement device, comprising: an execution unit that simultaneously executes a speed change operation to change the rotational speed of the spindle to a target speed and a feed operation to move the relative position of the spindle with respect to a specified object to a target coordinate system at least either before or after a tool change; a calculation unit that calculates the completion time of the speed change operation and the completion time of the feed operation; and a suppression unit that performs suppression control to suppress the absolute value of acceleration of the earlier-completed operation, whichever of the speed change operation and the feed operation has an earlier completion time in the calculation, thereby making the completion time of the earlier-completed operation later than if the suppression control was not performed.

2. A machine tool control device as described in claim 1, wherein the suppression unit delays the completion time of the earlier-completed operation through the suppression control within a range that does not make the completion time later than the completion time of the later-completed operation, which is the one of the speed change operation and the feed operation that had the later completion time in the calculation.

3. A machine tool control device as described in claim 2, further comprising a correction unit that, when the suppression control causes the completion time of the earlier completion operation to be later than the completion time of the later completion operation, performs a correction to suppress the suppression control, thereby preventing the completion time of the earlier completion operation from being later than the completion time of the later completion operation.

4. A machine tool control device as described in any one of claims 1 to 3, wherein the execution unit controls the machine tool based on a machining program, and includes an analysis unit that determines whether or not the speed change operation and the feed operation are performed simultaneously based on an analysis of the machining program, and the calculation unit performs the calculation on the condition that it is determined that the simultaneous execution is performed.

5. A machine tool control device as described in any one of claims 1 to 4, further comprising a judgment unit which judges whether or not suppression control is necessary based on the completion time of the speed change operation in the calculation and the completion time of the feed operation in the calculation, and the suppression unit performs the suppression control on the condition that it is judged that the suppression control is necessary.

6. A machine tool control device as described in any one of claims 1 to 5, wherein when the calculation shows that the completion time of the speed change operation is earlier than the completion time of the feed operation, the suppression unit suppresses the absolute value of the acceleration in the speed change operation by the suppression control.

7. A machine tool control device as described in any one of claims 1 to 6, wherein when the calculation shows that the completion time of the speed change operation is later than the completion time of the feed operation, the suppression section suppresses the absolute value of the acceleration in the feed operation by the suppression control.

8. A machine tool control device according to any one of claims 1 to 7, wherein the execution unit executes, as the speed change operation, an operation of decelerating the rotational speed of the spindle to zero as the target speed before the tool change, and executes, as the feed operation, an operation of moving the relative position to an exchange start coordinate as the target coordinate.

9. A machine tool control device according to any one of claims 1 to 8, wherein the execution unit executes, as the speed change operation, an operation of accelerating the rotational speed of the spindle to a machining speed as the target speed after the tool change, and executes, as the feed operation, an operation of moving the relative position to a machining start coordinate as the target coordinate.

10. A machine tool control program that causes a computer to function as a device for controlling a machine tool having a spindle and in which tools attached to the spindle are replaced by an exchange device, the machine tool control program causing the computer to function as: an execution unit that simultaneously executes a speed change operation to change the rotational speed of the spindle to a target speed and a feed operation to move the relative position of the spindle with respect to a specified object to a target coordinate system at least either before or after a tool change; a calculation unit that calculates the completion time of the speed change operation and the completion time of the feed operation; and a suppression unit that performs suppression control to suppress the absolute value of acceleration in the earlier-completed operation, whichever of the speed change operation and the feed operation, has an earlier completion time in the calculation, thereby making the completion time of the earlier-completed operation later than when the suppression control is not performed.

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