Control device of a machine tool

Abstract

The present invention provides a control device for a machine tool that can reduce the impact generated by the machine tool during oscillatory cutting. The control device (1) of the machine tool performs machining while relatively oscillating a tool and a workpiece, and includes: an oscillation command generation unit (13) that generates an oscillation command based on oscillation conditions; an oscillation start / end determination unit (14) that determines the start / end of oscillation based on the oscillation command; and a position / velocity control unit (18) that relatively oscillates the tool and the workpiece based on an overlapping command generated by overlapping the oscillation command on a movement command according to the determination result of the oscillation start / end determination unit (14). The oscillation start / end determination unit (14) determines the start / end of oscillation when the absolute value of the oscillation command is equal to or less than a specified value.

Description

Technical Field

[0001] The present invention relates to a control device for a machine tool. Background Art

[0002] Conventionally, as a chip control measure for drilling and turning, etc., oscillatory cutting has sometimes been applied. For example, a technique for overlapping a swing command with a movement command in order to perform oscillatory cutting is known (for example, refer to Patent Document 1). According to this technique, by the overlapping command generated by overlapping the swing command with the movement command, oscillatory cutting can be performed while cutting the chips into pieces.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-28597 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In addition, depending on the swing phase when starting / ending the overlap of the swing command with the movement command, a discontinuous overlap command is generated due to the overlap of the swing command. Due to such a discontinuous overlap command, the acceleration sometimes changes abruptly, and the machine tool generates an impact. If the machine tool generates an impact, it may have an adverse effect on the machining accuracy.

[0008] Therefore, a control device for a machine tool that can reduce the impact generated by the machine tool during oscillatory cutting is desired.

[0009] Means for Solving the Problems

[0010] One aspect of the present disclosure relates to a control device for a machine tool that performs machining while relatively swinging a tool and a workpiece, and includes: a swing command generation unit that generates a swing command based on swing conditions; a swing start / end determination unit that determines the start / end of the swing based on the swing command; and a control unit that relatively swings the tool and the workpiece based on an overlap command generated by overlapping the swing command with a movement command according to the determination result of the swing start / end determination unit, and the swing start / end determination unit determines the start / end of the swing when the absolute value of the swing command is equal to or less than a specified value.

[0011] Advantages of the Invention

[0012] According to one aspect of the present disclosure, a control device for a machine tool that can reduce the impact generated by the machine tool during oscillatory cutting can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1Shows the structure of the control device of the machine tool according to the first embodiment of the present invention.

[0014] Figure 2 Shows an example of a movement command.

[0015] Figure 3 Shows an example of a swing command.

[0016] Figure 4 Indicates the start / end pair Figure 2 of the movement command overlapping Figure 3 the overlapping command when the timing of the swing command deviates from the swing phases of 0° and 180°.

[0017] Figure 5 Indicates the start / end pair Figure 2 of the movement command overlapping Figure 3 the overlapping command when the timing of the swing command does not deviate from the swing phases of 0° and 180°.

[0018] Figure 6 Shows another example of a swing command.

[0019] Figure 7 Indicates the start / end pair Figure 2 of the movement command overlapping Figure 6 the overlapping command when the timing of the swing command deviates from the swing phase where the swing designation is 0.

[0020] Figure 8 Indicates the start / end pair Figure 2 of the movement command overlapping Figure 6 the overlapping command when the timing of the swing command does not deviate from the swing phase where the swing designation is 0.

[0021] Figure 9 Shows the structure of the control device of the machine tool according to the second embodiment of the present disclosure. Detailed implementation mode

[0022] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, in the description after the second embodiment, the description of the structures and effects common to the first embodiment will be omitted, and only the structures and effects different from the first embodiment will be described. In addition, in this specification, the swing command refers to the instantaneous value of the command at a certain swing phase, and the swing amplitude refers to the amplitude value of the sine wave or cosine wave.

[0023] [First Embodiment]

[0024] Figure 1 Is a functional block diagram of the control device 1 of the machine tool according to the first embodiment of the present disclosure. As Figure 1As shown, the control device 1 of the machine tool according to this embodiment is configured to include a servo control device 10, which drives and controls the motor 30 that drives the feed axis.

[0025] As Figure 1 shown, the control device 1 of the machine tool according to this embodiment includes a first adder 11, a swing condition setting unit 12, a swing command generation unit 13, a swing start / end determination unit 14, a second adder 15, a learning controller 16, a third adder 17, and a position and speed control unit 18.

[0026] As Figure 1 shown, in the control device 1 of the machine tool according to this embodiment, the movement command for the motor 30 generated by a movement command generation unit (not shown) based on machining conditions is input to the first adder 11 of the servo control device 10 described later.

[0027] The first adder 11 calculates the position deviation. Specifically, the first adder 11 calculates the difference between the position feedback based on the position detection by the encoder of the motor 30 of the feed axis and the position command, that is, the position deviation.

[0028] The swing condition setting unit 12 sets the swing conditions. Specifically, the swing condition setting unit 12 sets the swing amplitude or the swing amplitude magnification, the swing frequency or the swing frequency magnification. The swing conditions composed of these swing amplitude or swing amplitude magnification and swing frequency or swing frequency magnification are input to the swing command generation unit 13 described later.

[0029] The swing command generation unit 13 generates a swing command based on the swing conditions. The swing command generation unit 13 can obtain the swing command according to swing conditions such as the swing amplitude magnification and the swing frequency magnification and machining conditions, or can obtain the swing command according to swing conditions such as the swing amplitude and the swing frequency. In addition, the magnification and the non-magnification conditions can be arbitrarily combined. That is, also considering applications such as the case where the swing axis has stopped, as long as the swing amplitude and swing frequency are directly set by the swing conditions, the swing command can be generated without using the machining conditions.

[0030] The swing start / end determination unit 14 determines the start / end of the swing based on the swing command. The determination of the start / end of the swing performed by the swing start / end determination unit 14 will be described in detail later.

[0031] The second adder 15 generates an overlapping instruction. Specifically, the second adder 15 overlaps the swing instruction generated by the swing instruction generation unit 13 with respect to the position deviation calculated by the first adder 11, thereby generating an overlapping instruction. In addition, the second adder 15 may be configured to add the swing instruction generated by the swing instruction generation unit 13 to the movement instruction. Alternatively, it may be configured such that the swing instruction generation unit 13 generates a swing instruction (speed instruction), and the second adder 15 adds the swing instruction to the movement instruction (speed instruction).

[0032] In addition, the second adder 15 overlaps the swing instruction with respect to the position deviation according to the determination result of the swing start / end determination unit 14. That is, the second adder 15 starts overlapping the swing instruction with respect to the position deviation when the swing start / end determination unit 14 determines that the swing starts, and ends overlapping the swing instruction with respect to the position deviation when the swing start / end determination unit 14 determines that the swing ends.

[0033] The learning controller 16 calculates a correction amount of the overlapping instruction based on the overlapping instruction, and adds the calculated correction amount to the overlapping instruction by the third adder 17, thereby correcting the overlapping instruction. The learning controller 16 has a memory, stores the swing phase and the correction amount in association with each other in the memory for one cycle or a plurality of cycles of the swing, reads out the correction amount stored in the memory at a timing capable of compensating for the phase delay of the swing operation corresponding to the responsiveness of the motor 30, and outputs it to the third adder 17. When there is no swing phase for outputting the correction amount among the swing phases stored in the memory, the output correction amount can be calculated based on the correction amount close to the swing phase. Generally, the higher the swing frequency, the greater the position deviation with respect to the swing instruction. Therefore, by correcting with this learning controller 16, the followability for the periodic swing instruction can be improved. As a result, the followability for the overlapping instruction is also improved, and the impact generated by the machine tool during swing cutting can be reduced. Furthermore, the machining accuracy can be improved.

[0034] The position speed control unit 18 generates a torque instruction for the motor 30 that drives the feed axis based on the overlapping instruction added with the correction amount, and controls the motor 30 according to the generated torque instruction. Thereby, machining is performed while relatively swinging the tool and the workpiece.

[0035] Next, the determination of the start / end of the swing performed by the swing start / end determination unit 14 will be described in detail.

[0036] The swing start / end determination unit 14 of the present embodiment determines the start / end of the swing when the absolute value of the swing command is equal to or less than a specified value. The specified value is set to 0 or a value near 0, for example, and can also be calculated based on acceleration. At this timing, when the swing start / end condition is satisfied, it is determined that the swing starts / ends. For example, the determination can be made based on the swing amplitude, the movement command, the notification from the upper control device that manages the machining program, and the external signal. When the determination is made based on the swing amplitude and the movement command, if it is equal to or greater than the specified value, it is determined as the start, and if it is less than the specified value, it is determined as the end. The specified value for making the start / end determination can also have a hysteresis. When the determination is made based on the notification from the upper control device or the external signal, if the notification starts (ON), it is determined as the start, and if the notification ends (OFF), it is determined as the end. Since the absolute value of the swing command overlapping with the position deviation is equal to or less than the specified value, the generation of discontinuous overlapping commands at the start / end of the swing can be suppressed, and the impact generated by the machine tool can be reduced.

[0037] In addition, in the present embodiment, since the timing of the start / end of the swing is determined by the swing start / end determination unit 14, the timing of the start / end of the swing may deviate from the timing of the start / end of the swing specified by the machining program. The swing start / end determination unit 14 can be configured to determine the timing of the start / end of the swing such that the deviation amount from the timing of the start / end of the swing specified by the machining program is within a predetermined range.

[0038] Refer to Figures 2 - 8 The specific example shown is used to more specifically describe the determination of the start / end of the swing performed by the swing start / end determination unit 14.

[0039] Figure 2 is a diagram showing an example of the movement command, in the case where the movement command is constant. In Figure 2 the case where the movement command shown is a constant speed, it becomes a linear command in which time and the movement amount are in a proportional relationship. In addition, Figure 3 is a diagram showing an example of the swing command, in the case where it is a sine wave-shaped command.

[0040] Figure 4 Indicates the start / end pair Figure 2 of the movement command overlapping Figure 3 the swing command, and the overlapping command when the timing deviates from the swing phases of 0° and 180°. Figure 3 Since the swing command of Figure 3 is a sine wave, the swing command is 0 at the swing phases of 0° and 180°. Therefore, if the timing of the swing command of Figure 4 overlapping the start / end deviates from the swing phases of 0° and 180°, the swing command becomes a value other than 0. Therefore, as shown inFigure 4 In this case, the part surrounded by the dashed line indicates that a large impact occurs when the overlap starts / ends.

[0041] In contrast, Figure 5 indicating the start / end pair Figure 2 the movement instruction overlap of Figure 3 the timing of the swing instruction does not deviate from the overlap instruction when the swing phase is 0° and 180°. When the start / end overlap Figure 3 the timing of the swing instruction is at the swing phases of 0° and 180°, the swing instruction is 0. Therefore, as Figure 5 shown, the instructions at the overlap start / end are continuous and smooth. In Figure 5 this case, the part surrounded by the dashed line indicates that the impact is reduced when the overlap starts / ends.

[0042] In addition, Figure 6 shows other examples of the swing instruction. Like the swing instruction Figure 6 shown, it can also be a cosine-wave-shaped instruction with the position of the vertical axis offset.

[0043] Figure 7 indicating the start / end pair Figure 2 the movement instruction overlap of Figure 6 the timing of the swing instruction deviates from the overlap instruction when the swing phase where the swing specification becomes 0. Figure 6 The swing instruction of Figure 6 is a cosine wave and the position of the vertical axis is offset. According to Figure 6 it can be seen that when the swing phase is 0°, the swing instruction is 0. Therefore, if the timing of the swing instruction Figure 7 for the start / end overlap deviates from the swing phase of 0°, the swing instruction becomes a value other than 0. Therefore, as Figure 7 shown, the instructions at the overlap start / end are not continuous. In

[0044] In contrast, Figure 8 indicating the start / end pair Figure 2 the movement instruction overlap of Figure 6 the timing of the swing instruction does not deviate from the overlap instruction when the swing phase where the swing specification becomes 0. If the timing of the swing instruction Figure 6 for the start / end overlap is at the swing phase of 0°, the swing instruction is 0. Therefore, as Figure 8 shown, the instructions at the overlap start / end are continuous and smooth. In Figure 8 this case, the part surrounded by the dashed line indicates that the impact is reduced when the overlap starts / ends.

[0045] As Figures 2 - 8 ​​​As described, by starting / ending the swing at a timing with a small swing command, the impact generated by the machine tool can be reduced.

[0046] The control device 1 of the machine tool according to the present embodiment has the following effects.

[0047] In the present embodiment, it is configured to provide a swing start / end determination unit 14 that determines the start / end of the swing based on the swing command, and generates an overlapping command by overlapping the swing command with the movement command according to the determination result of the swing start / end determination unit 14. In addition, it is configured to determine the start / end of the swing by the swing start / end determination unit 14 when the absolute value of the swing command is equal to or less than a specified value.

[0048] Thereby, when the absolute value of the swing command is equal to or less than the specified value, the swing command is overlapped with the movement command at the start / end, so that the generation of discontinuous commands can be suppressed, and the impact generated by the machine tool can be reduced. In addition, the machining accuracy of the swing cutting process can be improved.

[0049] [Second Embodiment]

[0050] Figure 9 The structure of the control device 1A of the machine tool showing the second embodiment of the present disclosure is as follows. As Figure 9 shown, the control device 1A of the machine tool in the second embodiment is different from that in the first embodiment in that it is configured to include a servo control device 10A, and further includes a swing amplitude calculation unit 121 and a swing phase calculation unit 122. In addition, the swing command generation unit 13A corresponds to the swing command generation unit 13 in the first embodiment, the swing start / end determination unit 14A corresponds to the swing start / end determination unit 14 in the first embodiment, and other structures are the same as those in the first embodiment.

[0051] The swing amplitude calculation unit 121 calculates the swing amplitude based on the swing conditions. For example, the swing amplitude calculation unit 121 calculates the swing amplitude based on the swing amplitude magnification factor set by the swing condition setting unit 12.

[0052] The swing phase calculation unit 122 calculates the swing phase according to the swing conditions. For example, the swing phase calculation unit 122 calculates the swing phase (swing frequency) based on the swing frequency magnification factor set by the swing condition setting unit 12.

[0053] The swing command generation unit 13A in the present embodiment generates a swing command based on the swing amplitude calculated by the swing amplitude calculation unit 121 and the swing phase calculated by the swing phase calculation unit 122.

[0054] The swing start / end determination unit 14A of the present embodiment determines the start / end of the swing based on at least one of the swing amplitude calculated by the swing amplitude calculation unit 121 and the swing phase calculated by the swing phase calculation unit 122.

[0055] More specifically, the swing start / end determination unit 14A can, for example, determine the start / end of the swing when the swing amplitude (amplitude value of a sine wave or cosine wave) is below a specified value. Thereby, it is possible to suppress discontinuous commands during the overlapping start / overlapping end of the swing command.

[0056] In addition, the swing start / end determination unit 14A can also determine the start / end of the swing at a swing phase when the absolute value of the swing command is below a specified value. By setting the specified value to 0, it is possible to further reduce the impact. If it is the case of the sine-wave-shaped swing command shown above Figure 3 then it is only necessary to determine the start / end of the swing when the swing phase is 0° or 180°. In addition, if it is the case of the cosine-wave-shaped swing command with the position of the vertical axis offset as shown above Figure 6 then it is only necessary to determine the start / end of the swing when the swing phase is 0°.

[0057] According to the present embodiment, similar to the first embodiment, when the absolute value of the swing command is below a specified value, the swing command is started / ended to overlap the movement command. Therefore, it is possible to suppress the generation of discontinuous commands and reduce the impact generated by the machine tool. And it is possible to improve the machining accuracy of the swing cutting process.

[0058] Furthermore, the present disclosure is not limited to the above-described mode, and modifications and improvements within the scope that can achieve the object of the present disclosure are also included in the present disclosure.

[0059] For example, in the second embodiment, it is configured to include the swing amplitude calculation unit 121 and the swing phase calculation unit 122, but it can also be configured to include only one of them.

[0060] Explanation of reference numerals

[0061] 1, 1A Control device of the machine tool

[0062] 10, 10A Servo control device

[0063] 11 First adder

[0064] 12 Swing condition setting unit

[0065] 13, 13A Swing command generation unit

[0066] 14, 14A Swing start / end determination unit

[0067] 15 Second adder

[0068] 16 Learning controller (learning control unit)

[0069] 17 Third adder (learning control unit)

[0070] 18 Position and speed control unit (control unit)

[0071] 30 Motor

[0072] 121 Swing amplitude calculation unit

[0073] 122 Swing phase calculation unit.

Claims

1. A control device for a machine tool, which performs machining while relatively swinging a tool and a workpiece, characterized in that: The control device includes: A swing command generation unit that generates a swing command based on swing conditions; A swing start / end determination unit that determines the start / end of swinging based on the swing command; and A control unit that relatively swings the tool and the workpiece based on an overlapping command generated by overlapping the swing command on a movement command according to the determination result of the swing start / end determination unit, The swing start / end determination unit determines the start / end of swinging when the absolute value of the swing command is equal to or less than a specified value.

2. The control device for a machine tool according to claim 1, characterized in that: The control device further includes a swing amplitude calculation unit that calculates a swing amplitude based on the swing conditions, The swing command generation unit calculates the swing command based on the swing amplitude, The swing start / end determination unit determines the start / end of swinging based on the swing amplitude.

3. The control device for a machine tool according to claim 1, characterized in that: The control device further includes a swing phase calculation unit that calculates a swing phase based on the swing conditions, The swing command generation unit generates the swing command based on the swing phase, The swing start / end determination unit determines the start / end of swinging based on the swing phase.

4. The control device for a machine tool according to claim 2, characterized in that: The control device further includes a swing phase calculation unit that calculates a swing phase based on the swing conditions, The swing command generation unit generates the swing command based on the swing phase, The swing start / end determination unit determines the start / end of swinging based on the swing phase.

5. The control device for a machine tool according to claim 3, characterized in that: The swing start / end determination unit determines the start / end of swinging at the swing phase when the swing command becomes 0.

6. The control device for a machine tool according to claim 4, characterized in that: The swing start / end determination unit determines the start / end of swinging at the swing phase when the swing command becomes 0.

7. The control device for a machine tool according to any one of claims 1 to 6, characterized in that: The swing start / end determination unit determines that swinging starts when a swing start is notified by an external signal and a predetermined swing start condition is satisfied, and determines that swinging ends when a swing end is notified by an external signal and a predetermined swing end condition is satisfied.

8. The control device for a machine tool according to any one of claims 1 to 6, characterized in that: The control device further includes a learning control unit that calculates a correction amount of the overlapping command based on the overlapping command and corrects the overlapping command by adding the calculated correction amount to the overlapping command.

9. The control device for a machine tool according to claim 7, characterized in that: The control device further includes a learning control unit that calculates a correction amount of the overlapping instruction based on the overlapping instruction, and corrects the overlapping instruction by adding the calculated correction amount to the overlapping instruction.

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