Control device for machine tools

Abstract

In a control device of a machine tool that processes a workpiece by vibration-controlling a control shaft, the entire machine tool is reliably suppressed from wobbling. The control device of the machine tool includes: a vibration condition setting section that sets a vibration condition including at least one of a frequency parameter composed of a vibration frequency or a vibration frequency multiplier, an amplitude parameter composed of a vibration amplitude or a vibration amplitude multiplier, and a vibration direction; a vibration upper limit setting section that sets an upper limit value of a vibration parameter determined by the vibration condition, including at least one of a vibration frequency, a vibration amplitude, a vibration velocity, a vibration acceleration, and a vibration jerk, according to one or both of the vibration frequency and the vibration direction; a vibration condition restriction section that restricts the vibration condition set by the vibration condition setting section based on the upper limit value of the vibration parameter; and a vibration control section that vibration-controls the control shaft based on the vibration condition restricted by the vibration condition restriction section.

Description

Technical Field

[0001] This disclosure relates to control devices for machine tools. Background Technology

[0002] Previously, machine tool control devices were known to control the movement of a control axis while it vibrates, such as in oscillating cutting or crank pin machining, to process workpieces. However, if the control axis is vibrated in this way, excessive oscillation may sometimes occur throughout the machine tool, adversely affecting machining accuracy.

[0003] Therefore, in order to prevent excessive oscillation of the entire machine tool caused by the vibration of the control axis, the following technique has been proposed: setting the acceleration of the vibration and an upper limit value of the acceleration, and performing vibration control within the set upper limit value (for example, see Patent Document 1). According to this technique, a good finished surface can be ensured.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2007-044849 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, due to the inherent resonant frequency of the machine tool and the different inertia of each control axis, for example, when setting an upper limit for vibration acceleration to reduce vibration acceleration, sometimes the oscillation of the entire machine tool actually increases. That is, setting only the upper limit for vibration acceleration and jerk without considering the vibration frequency and the inertia of the control axes cannot reliably suppress the oscillation of the entire machine tool.

[0009] Therefore, a technology is desired that can reliably suppress the oscillation of the entire machine tool in the control device of a machine tool that processes workpieces by controlling the vibration of the control axis.

[0010] Methods for solving problems

[0011] One aspect of this disclosure is a control device for a machine tool that performs machining while vibrating the tool relative to the workpiece. The control device comprises: a vibration condition setting unit that sets vibration conditions, the vibration conditions including at least one of a frequency parameter consisting of a vibration frequency or a multiple of a vibration frequency, an amplitude parameter consisting of a vibration amplitude or a multiple of a vibration amplitude, and a vibration direction; a vibration upper limit setting unit that sets an upper limit value of the vibration parameter determined by the vibration conditions based on one or both of the vibration frequency and the vibration direction, the vibration parameter including at least one of a vibration frequency, vibration amplitude, vibration velocity, vibration acceleration, and vibration jerk; a vibration condition limiting unit that limits the vibration conditions set by the vibration condition setting unit based on the upper limit value of the vibration parameters; and a vibration control unit that performs vibration control on a control axis based on the vibration conditions limited by the vibration condition limiting unit.

[0012] Invention Effects

[0013] According to this disclosure, in the control device of a machine tool that performs vibration control on the control axis to process workpieces, the oscillation of the entire machine tool can be reliably suppressed. Attached Figure Description

[0014] Figure 1 Control device for a machine tool according to an embodiment of the present disclosure.

[0015] Figure 2 Vibration control used to illustrate the above-described embodiments.

[0016] Figure 3 This is the first example of vibration control according to the above-described implementation method.

[0017] Figure 4 This is a second example of vibration control according to the above-described implementation method. Detailed Implementation

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0019] Figure 1 The control device 1 of the machine tool according to this embodiment is shown. The control device 1 of the machine tool in this embodiment performs cutting machining on a workpiece using a tool by operating at least one spindle and at least one feed axis. The at least one spindle rotates the cutting tool (hereinafter referred to as the tool) relative to the workpiece, and the at least one feed axis moves the tool relative to the workpiece. Furthermore, in Figure 1 For convenience, only the motor 3 driving one feed axis is shown in the image.

[0020] The machine tool control device 1 of this embodiment performs oscillating cutting (hereinafter also referred to as vibration cutting) by moving the spindle and feed axis. That is, the machine tool control device 1 performs cutting while rotating the tool relative to the workpiece and oscillating (hereinafter also referred to as vibration) the tool relative to the workpiece. The tool path, which is the tool trajectory, is set such that the current path partially overlaps with the previous path, and the portion already processed in the previous path is included in the current path. Therefore, by generating a free swing (free cut) in which the tool tip leaves the surface of the workpiece, the chips continuously generated by the cutting process can be reliably broken.

[0021] Furthermore, this embodiment can be applied not only to structures in which the tool oscillates relative to a workpiece rotating about its central axis while moving in the feed direction, but also to structures in which the tool T rotates about the central axis of the workpiece and the workpiece moves relative to the tool in the feed direction. Additionally, this embodiment can be applied to either outer diameter machining or inner diameter machining of a workpiece. Moreover, this embodiment can be applied not only to cases where multiple feed axes (Z-axis and X-axis) are required because the workpiece has a tapered or arc-shaped portion on the machining surface, but also to cases where the workpiece is cylindrical or cylindrical and a single feed axis (Z-axis) is sufficient.

[0022] The machine tool's control device 1 is configured, for example, using a computer. This computer includes memories such as ROM (read-only memory) and RAM (random access memory), a CPU (central processing unit), and a communication control unit, all interconnected via a bus. Figure 1 As shown, the machine tool control device 1 includes a vibration condition setting unit 11, a vibration condition limiting unit 12, a vibration upper limit setting unit 13, a vibration control unit 14, and a display unit 15. The functions and actions of these units can be realized through the cooperation of the CPU, memory, and control program stored in the memory of the computer.

[0023] In addition, a host computer (not shown) such as a CNC (Computer Numerical Controller) or a PLC (Programmable Logic Controller) is connected to the machine tool's control unit 1. These host computers input machining programs, rotational speeds, feed rates, and other workpiece machining conditions to the machine tool's control unit 1.

[0024] The machining conditions for the workpiece include the relative rotational speed of the workpiece and the tool around the central axis of the workpiece, the relative feed rate of the tool and the workpiece, and the position command of the feed axis. In this embodiment, the CPU in the machine tool's control device 1 can be configured to read the rotational speed and feed rate from the input machining program as machining conditions and output them to the vibration control unit 14. The position command generation unit in the vibration control unit 14 can also be provided in the aforementioned host computer.

[0025] The vibration condition setting unit 11 sets vibration conditions, which include at least one of the following: a frequency parameter consisting of a vibration frequency or a multiple of a vibration frequency; an amplitude parameter consisting of a vibration amplitude or a multiple of a vibration amplitude; and a vibration direction. Based on the machining program and machining conditions input to the machine tool's control device 1, the vibration condition setting unit 11 sets the aforementioned vibration conditions under the constraints of the vibration condition limiting unit 12 (described later). The vibration conditions set by the vibration condition setting unit 11 are then output to the vibration control unit 14 (described later).

[0026] Here, the vibration frequency ratio is a frequency parameter obtained by dividing the vibration frequency by the spindle speed. The vibration amplitude ratio is an amplitude parameter obtained by dividing the vibration amplitude by half the feed amount of the feed axis per revolution of the spindle. The vibration direction is represented, for example, by the inclination θ relative to the workpiece's center axis (Z-axis direction) (see below). Figure 4 ).

[0027] The vibration upper limit setting unit 13 sets an upper limit value for a vibration parameter, including at least one of vibration frequency, vibration amplitude, vibration velocity, vibration acceleration, and vibration jerk, determined by the aforementioned vibration conditions, based on one or both of vibration frequency and vibration direction. The upper limit value of the vibration parameter set by the vibration upper limit setting unit 13 is output to the vibration condition limiting unit 12, which will be described later.

[0028] When the vibration upper limit setting unit 13 sets the upper limit value of the vibration parameter based on the vibration frequency, it is preferable to set the upper limit value of the vibration parameter by gradually or continuously decreasing it as the vibration frequency increases. This is because the higher the vibration frequency, the more easily the machine tool oscillates. For example, the vibration upper limit setting unit 13 is set to decrease the upper limit value of vibration parameters such as the acceleration upper limit as the vibration frequency increases in 10Hz intervals such as 0-10Hz, 10-20Hz, 20-30Hz, etc. (see below). Figure 3 ).

[0029] The oscillation of the entire machine tool, which accompanies the vibration control of the control axis, originates from the frequency, amplitude, velocity, acceleration, and jerk of the vibration. These vibration amplitudes, velocities, accelerations, and jerks are influenced by the vibration frequency. In contrast, in this embodiment, upper limits for vibration parameters such as vibration frequency, vibration amplitude, vibration velocity, vibration acceleration, and vibration jerk are set based on the vibration frequency. Therefore, by setting vibration conditions based on these upper limits for vibration parameters, the oscillation of the entire machine tool can be effectively suppressed.

[0030] The vibration upper limit setting unit 13 is more preferably set to a value smaller than that for other frequencies when the vibration frequency is comparable to the inherent resonant frequency of the machine tool. For example, when the inherent resonant frequency of the machine tool is 40Hz to 50Hz, the vibration upper limit setting unit 13 sets a vibration parameter upper limit value smaller than that for other vibration frequencies, i.e., vibration frequencies less than 40Hz or greater than 50Hz.

[0031] In vibration control of the control axis, when the vibration frequency is comparable to the machine tool's inherent resonant frequency, the machine tool and the control axis vibrate more synchronously. In contrast, in this embodiment, when the vibration frequency is equivalent to the resonant frequency, the upper limit of the vibration parameter is set to be smaller. Therefore, by setting the vibration conditions based on such an upper limit of the vibration parameter, the oscillation of the entire machine tool can be suppressed more effectively.

[0032] Furthermore, the case where the vibration frequency is equivalent to the resonant frequency includes situations where the machine tool's inherent resonant frequency is included within a vibration frequency band of a certain width, such as 10Hz. In this case, the width of the vibration frequency band should be appropriately set.

[0033] Furthermore, the vibration upper limit setting unit 13 may preferably set the upper limit value of the aforementioned vibration parameters to decrease in stages or continuously as the inclination of the vibration direction relative to the central axis direction of the workpiece increases. In this case, for example, it may be set such that as the inclination θ of the oscillation direction (hereinafter also referred to as the vibration direction) relative to the central axis (Z-axis direction) of the workpiece increases at 10° intervals such as 0°~10°, 10°~20°, 20°~30°, the upper limit value of vibration parameters such as the upper limit value of acceleration decreases (see below). Figure 4 ).

[0034] For example, many heavy objects such as servo motors are arranged in the X-axis direction (radial direction of the workpiece), which is orthogonal to the Z-axis direction (the direction of the workpiece's central axis). Therefore, compared to the Z-axis, the X-axis control axis has a larger vibration amount and a larger moment of inertia. The moment of inertia of the control axis varies depending on the machine tool, so the oscillation of the entire machine tool caused by the vibration of the control axis is affected by the vibration direction, which represents the ratio of the vibration amount of the control axis. In contrast, in this embodiment, the upper limit value of vibration parameters such as vibration acceleration and vibration jerk is set according to the vibration direction, specifically according to the inclination θ of the vibration direction relative to the Z-axis. Therefore, by setting the vibration conditions according to the upper limit value of the vibration parameters set in this way, the oscillation of the entire machine tool can be suppressed more effectively.

[0035] Of course, the magnitudes of the inertia of the Z-axis and X-axis vary depending on the mechanical structure, so sometimes the Z-axis has a larger inertia than the X-axis. In this case, it is set so that the tilt θ of the vibration direction relative to the Z-axis increases at 10° intervals, such as 0°~10°, 10°~20°, 20°~30°, thereby increasing the upper limit of vibration parameters such as the upper limit of acceleration, and thus more effectively suppressing the oscillation of the entire machine tool.

[0036] Furthermore, it is preferable that the vibration upper limit setting unit 13 sets the upper limit value of the aforementioned vibration parameter to different values ​​depending on whether the vibration direction is parallel to or not parallel to the drive direction of each control axis. The case where the vibration direction is parallel to the drive direction of each control axis refers to when only one axis among the control axes vibrates; the case where it is not parallel refers to when multiple drive axes vibrate in tandem. That is, it is preferable to set the upper limit value of the vibration parameter when multiple drive axes vibrate in tandem, separately from the upper limit value of the vibration parameter for each control axis. This can sometimes more effectively suppress the oscillation of the entire machine tool.

[0037] In addition, when the vibration upper limit setting unit 13 sets the upper limit value of the vibration parameter based on the vibration direction, it can also set the vibration frequency as the upper limit value of the vibration parameter. In this case, if the vibration frequency increases, the machine tool's oscillation also increases. Therefore, it is preferable that the greater the inclination of the vibration direction relative to the workpiece's central axis, the smaller the upper limit value of the vibration frequency should be.

[0038] In addition, the vibration upper limit setting unit 13 can measure the machine tool's oscillation when the vibration control of the control axis is actually executed in advance, in addition to the user's visual observation, through various sensors, and determine the upper limit value of the vibration parameters based on these results.

[0039] The vibration condition limiting unit 12 limits the vibration conditions set by the vibration condition setting unit 11 based on the upper limit value of the vibration parameters set by the vibration upper limit setting unit 13. Specifically, the vibration condition limiting unit 12 obtains the frequency parameters and vibration direction from the vibration condition setting unit 11, and uses the upper limit value of the vibration parameters corresponding to the obtained frequency parameters and vibration direction to limit the vibration conditions.

[0040] The vibration condition limiting unit 12 preferably limits the vibration conditions set by the vibration condition setting unit 11 so as not to exceed the upper limit value of the vibration parameters corresponding to the obtained frequency parameters and vibration direction. For example, the vibration condition limiting unit 12 clamps the vibration frequency, vibration amplitude, etc., within the range not exceeding the upper limit value of the vibration parameters. Alternatively, if the upper limit value of the vibration parameters is exceeded, the vibration condition limiting unit 12 issues an alarm (warning) and stops the processing program.

[0041] The vibration control unit 14 performs vibration control on the control axis based on the vibration conditions set by the vibration condition setting unit 11 under the restriction of the vibration condition limiting unit 12. In order to perform vibration control on the control axis, the vibration control unit 14 includes various functional units (not shown), such as a position command generation unit, a vibration command generation unit, an overlap command generation unit, a learning control unit, and a position and speed control unit.

[0042] The position command generation unit generates position commands as movement commands for the motor 3 based on the machining program and machining conditions input to the machine tool's control device 1. Specifically, the position command generation unit generates position commands (movement commands) for each feed axis based on the relative rotational speed of the workpiece and the tool around the workpiece's central axis and the relative feed speed of the tool and the workpiece.

[0043] The vibration command generation unit generates vibration commands. The vibration command generation unit generates vibration commands based on the vibration conditions set by the vibration condition setting unit 11.

[0044] The overlap command generation unit calculates the difference between the position feedback obtained from the position detection by the encoder of the feed axis motor 3 and the position command, i.e., the position deviation, and overlays the calculated position deviation with the vibration command generated by the vibration command generation unit, thereby generating an overlap command. Alternatively, the vibration command can be overlaid on the position command instead of the position deviation.

[0045] The learning control unit calculates the correction amount for the overlap command based on the overlap command, adds the calculated correction amount to the overlap command, and thereby corrects the overlap command. The learning control unit has a memory that associates the vibration phase with the correction amount and stores it in the memory within one or more vibration cycles. At a timing that compensates for the phase delay of the vibration action corresponding to the responsiveness of the motor 3, the overlapping command stored in the memory is read out and output as the correction amount. If no vibration phase with an output correction amount is stored in the memory, the correction amount to be output can be calculated based on a correction amount close to the vibration phase. Generally, the higher the vibration frequency, the greater the positional deviation relative to the vibration command; therefore, by using this learning control unit for correction, the tracking accuracy for periodic vibration commands can be improved.

[0046] The position and speed control unit generates a torque command for the motor 3 driving the feed axis based on the overlap command with a correction amount, and controls the motor 3 using the generated torque command. Thus, machining is performed while the tool T vibrates relative to the workpiece W.

[0047] The display unit 15 displays the upper limit value of the vibration parameters set by the vibration upper limit setting unit 13, and the vibration conditions set by the vibration condition setting unit 11, which are limited by the vibration condition limiting unit 12 based on the upper limit value. In addition to displaying various setting parameters, the display unit 15 also displays the machining program input to the machine tool control device 1. Thus, the user can set the upper limit value of the vibration parameters and the vibration conditions through the input unit (not shown) while checking the display screen.

[0048] Next, the vibration control of the control axis executed by the control device 1 of the machine tool in this embodiment will be explained.

[0049] Figure 2 This is used to illustrate the vibration control in this embodiment. For example... Figure 2 As shown, for example, satisfying a vibration acceleration of 1800000 mm / min 2 There are multiple combinations of vibration frequency and vibration amplitude. Figure 2 The diagram illustrates modes 1 through 3, where the vibration acceleration, determined by the vibration conditions, is 1800,000 mm / min. 2 The vibration acceleration is calculated using the following mathematical formula (1).

[0050] [Number 1]

[0051] Vibration acceleration = α × (vibration amplitude) × (vibration frequency) 2 Equation (1)

[0052] Here, as Figure 2As shown in the display unit 15, the upper limit of acceleration is set to 1800000 mm / min by the vibration upper limit setting unit 13. 2 The vibration frequency is 40Hz and the vibration amplitude is 0.2mm as specified by the machining program. In this case, compared with mode 1 where the vibration frequency is 40Hz and the vibration amplitude is 0.015mm, the vibration acceleration calculated based on the above mathematical formula (1) exceeds the upper limit of 1800000 [mm / min]. 2 Therefore, the entire machine tool experiences large oscillations.

[0053] Therefore, in this embodiment, in order to ensure that the vibration acceleration does not exceed the upper limit of 1800000 mm / min 2 The vibration condition limiting unit 12 clamps the vibration amplitude at 0.015 mm while maintaining a vibration frequency of 40 Hz. Then, the vibration condition setting unit 11 sets the vibration frequency of 40 Hz and the clamped vibration amplitude of 0.015 mm as the vibration conditions. As a result, the vibration acceleration becomes an upper limit of 1800000 mm / min. 2 This reliably suppresses the oscillations generated by the entire machine tool.

[0054] Furthermore, clamping is not limited to vibration amplitude; it can also clamp vibration frequency, or even both vibration amplitude and vibration frequency. As a method for limiting vibration conditions, clamping is not limited to it; for example, it can be configured to issue an alarm and stop the processing procedure if vibration parameters such as vibration acceleration exceed their upper limit values.

[0055] Figure 3 This represents the first example of vibration control in this embodiment. Figure 3 The first example shown is an example of setting the upper limit of vibration acceleration based on the vibration frequency. Specifically, as... Figure 3 As shown in the display unit 15, the upper limit of the vibration acceleration when the vibration frequency is 0Hz to 10Hz (meaning above 0 and below 10Hz) is 2000000 mm / min. 2 The upper limit of vibration acceleration at 10–20 Hz is 1,900,000 mm / min; the upper limit of vibration acceleration at 20–30 Hz is 1,800,000 mm / min. 2 The upper limit of vibration acceleration at 30-40Hz is 1600000 mm / min. 2 The upper limit of vibration acceleration at 40–50 Hz is 1,000,000 mm / min. 2 The upper limit of vibration acceleration at 50-60Hz is 1,500,000 mm / min. 2In this way, an upper limit value for vibration acceleration is set for each vibration frequency band with a 10Hz interval. In addition, in this first example, an upper limit value for acceleration that decreases as the vibration frequency increases is set. Furthermore, a minimum upper limit value for acceleration is set at 40Hz to 50Hz, which corresponds to the resonant frequency of the machine tool.

[0056] In this first example, such as Figure 3 As shown in the display unit 15, the vibration frequency for vibratory cutting specified by the machining program input to the machine tool control device 1 is 25Hz, and the vibration amplitude is 0.1mm. If the vibration acceleration at a vibration frequency of 25Hz and a vibration amplitude of 0.1mm is calculated using the above mathematical formula (1), it exceeds the upper limit of vibration acceleration at a vibration frequency of 25Hz, which is 1800000 mm / min. 2 Therefore, in this first example, while maintaining a vibration frequency of 25Hz, the vibration amplitude is changed to a smaller value. When the calculated vibration acceleration does not exceed the upper limit of vibration acceleration, the vibration amplitude is clamped to this value, 0.0384mm. In this way, by setting the vibration condition to not exceed the upper limit of vibration acceleration, the oscillation generated by the entire machine tool can be reliably suppressed.

[0057] Figure 4 This is a second example of vibration control in this embodiment. Figure 4 The second example shown is an example of setting the upper limit of vibration acceleration based on the direction of vibration. Specifically, as... Figure 4 As shown in the display unit 15, when the inclination θ of the vibration direction relative to the Z-axis is 0° to 10° (above 0° and less than 10°, and the same applies below), the upper limit of the vibration acceleration is set to 2000000 mm / min. 2 [, set to 1900000 [mm / min] at 10°~20°. 2 [, set to 1800000 [mm / min] at 20°–30°. 2 [, set to 1600000 [mm / min] at 30°~40°. 2 [, set to 1400000 [mm / min] at 40°~50°. 2 [, set to 1100000 [mm / min] at 50°~60°. 2 Thus, an upper limit value for vibration acceleration was set for each tilt angle band at 10° intervals. In addition, in this second example, an upper limit value for acceleration was set that decreases as the tilt of the vibration direction relative to the Z-axis increases.

[0058] In this second example, such as Figure 4As shown in the display unit 15, the vibration frequency of the vibration cutting specified by the machining program input to the machine tool control device 1 is 25Hz, and the vibration amplitude is 0.04mm. Furthermore, the movement direction of the movement command specified by the machining program is determined to be 45° based on the X-coordinate position and Z-coordinate position specified by G00 and G01. Here, in the vibration cutting of this example, the vibration direction is the same as the movement direction of the movement command, therefore the inclination θ of the vibration direction relative to the Z-axis is 45°. If the vibration acceleration at a vibration frequency of 25Hz and a vibration amplitude of 0.04mm is calculated using the above mathematical formula (1), it exceeds the upper limit of 1400000 mm / min for the vibration acceleration when the vibration direction is tilted θ to the Z-axis at 45°. 2 Therefore, in this second example, while maintaining a vibration frequency of 25Hz, the vibration amplitude is changed to a smaller value. When the calculated vibration acceleration does not exceed the upper limit of vibration acceleration, the vibration amplitude is clamped to this value, 0.0299mm. In this way, by setting the vibration condition to not exceed the upper limit of vibration acceleration, the oscillation generated by the entire machine tool can be reliably suppressed.

[0059] According to this embodiment, the following effects are achieved.

[0060] The machine tool control device 1 of this embodiment includes: a vibration condition setting unit 11, which sets vibration conditions, including at least one of a frequency parameter composed of a vibration frequency or a multiple of a vibration frequency, an amplitude parameter composed of a vibration amplitude or a multiple of a vibration amplitude, and a vibration direction; and a vibration upper limit setting unit 13, which sets an upper limit value of a vibration parameter determined by the vibration conditions, including at least one of a vibration frequency, a vibration amplitude, a vibration velocity, a vibration acceleration, and a vibration jerk, based on one or both of the vibration frequency and the vibration direction. Furthermore, the machine tool control device 1 of this embodiment includes: a vibration condition limiting unit 12, which limits the vibration conditions set by the vibration condition setting unit 11 based on the upper limit value of the vibration parameters; and a vibration control unit 14, which performs vibration control on the control axis based on the vibration conditions limited by the vibration condition limiting unit 12.

[0061] The oscillation of the entire machine tool, which is associated with the vibration control of the control axis, is mainly caused by vibration parameters such as vibration acceleration and jerk, which are affected by the vibration frequency and vibration direction. In contrast, according to this embodiment, the vibration condition limiting unit 12 limits the vibration conditions set by the vibration condition setting unit 11 based on the upper limit value of the vibration parameters set by the vibration upper limit setting unit 13 according to one or both of the vibration frequency and vibration direction. Therefore, in the vibration control of the control axis, vibration conditions can be achieved that do not exceed the upper limit value of the vibration parameters set according to the vibration frequency and vibration direction, thereby reliably suppressing the oscillation generated throughout the machine tool.

[0062] Furthermore, in this embodiment, the vibration upper limit setting unit 13 sets the upper limit value of the vibration parameter to decrease gradually or continuously as the vibration frequency increases. The higher the vibration frequency, the more easily the machine tool wobbles. According to this embodiment, a more appropriate upper limit value of the vibration parameter can be set based on the vibration frequency, thus more reliably suppressing the wobbling generated by the entire machine tool.

[0063] Furthermore, the vibration upper limit setting unit 13 of this embodiment sets different upper limit values ​​for vibration parameters depending on whether the vibration direction is parallel to or not parallel to the drive direction of each control axis. This can sometimes more effectively suppress the oscillation of the entire machine tool.

[0064] Furthermore, in this embodiment, the vibration upper limit setting unit 13 sets the upper limit value of the vibration parameter to decrease or increase in stages or continuously as the inclination θ of the vibration direction relative to the central axis direction (Z-axis) of the workpiece increases. Depending on the mechanical structure, the greater the inclination θ of the vibration direction relative to the central axis direction (Z-axis) of the workpiece, the easier or more difficult it is for the machine tool to oscillate. According to this embodiment, a more appropriate upper limit value of the vibration parameter can be set according to the vibration direction, thus more reliably suppressing the oscillation generated by the entire machine tool.

[0065] Furthermore, in this embodiment, the vibration upper limit setting unit 13 sets the upper limit value of the vibration parameter to a value smaller than that for other frequencies when the vibration frequency is equivalent to the machine tool's inherent resonant frequency. When the vibration frequency is equivalent to the machine tool's resonant frequency, the machine tool is prone to wobbling. According to this embodiment, a more appropriate upper limit value of the vibration parameter can be set based on the resonant frequency, thus more reliably suppressing the wobbling generated by the entire machine tool.

[0066] Furthermore, in this embodiment, the vibration condition limiting unit 12 limits the vibration conditions set by the vibration condition setting unit 11 so that they do not exceed the upper limit value of the vibration parameters. Therefore, according to this embodiment, situations where the upper limit value of the vibration parameters is exceeded can be reliably avoided, thereby more reliably suppressing the oscillations generated by the entire machine tool.

[0067] Furthermore, this disclosure is not limited to the above-described methods; variations and improvements within the scope of achieving the purpose of this disclosure are included in this disclosure.

[0068] For example, in the above embodiments, the present invention is applied to vibration cutting, but is not limited thereto. It can also be applied to control devices of machine tools that control the movement of the control shaft while vibrating to process workpieces, such as in crank pin machining, and can achieve the same effects as in the above embodiments.

[0069] Furthermore, in the above embodiments, examples of setting the upper limit value of the vibration parameter based on the vibration frequency and examples of setting the upper limit value of the vibration parameter based on the vibration direction have been described, but the method is not limited to these. The upper limit value of the vibration parameter can also be set based on both the vibration frequency and the vibration direction.

[0070] Furthermore, in the above embodiment, the machine tool control device 1 is configured to include a display unit 15, but it is not limited to this. The machine tool control device 1 may not include a display unit 15, and may be installed in the aforementioned host computer or the like.

[0071] Explanation of reference numerals in the attached figures

[0072] 1. Machine tool control device

[0073] 3 electric motors

[0074] 11 Vibration Condition Setting Section

[0075] 12 Vibration Condition Limitation Section

[0076] 13 Vibration Upper Limit Setting Section

[0077] 14 Vibration Control Department

[0078] 15. Display section.

Claims

1. A control device for a machine tool, which performs machining while vibrating the tool relative to the workpiece, characterized in that, The control device has: The vibration condition setting unit sets vibration conditions, which include at least one of the following: a frequency parameter consisting of a vibration frequency or a multiple of a vibration frequency, an amplitude parameter consisting of a vibration amplitude or a multiple of a vibration amplitude, and a vibration direction. The vibration upper limit setting unit sets an upper limit value for a vibration parameter determined by the vibration conditions based on the vibration frequency. This vibration parameter includes at least one of vibration amplitude, vibration velocity, vibration acceleration, and vibration jerk. A vibration condition limiting unit, which limits the vibration conditions set by the vibration condition setting unit based on the upper limit value of the vibration parameters; and The vibration control unit controls the vibration of the control shaft according to the vibration conditions limited by the vibration condition limiting unit.

2. The machine tool control device according to claim 1, characterized in that, The vibration upper limit setting unit sets the upper limit value of the vibration parameter to decrease in stages or continuously as the vibration frequency increases.

3. The machine tool control device according to claim 2, characterized in that, When the vibration frequency is a frequency comparable to the inherent resonant frequency of the machine tool, the vibration upper limit setting unit sets the upper limit value of the vibration parameter to a value smaller than that for other frequencies.

4. The machine tool control device according to claim 1, characterized in that, When the vibration frequency is a frequency comparable to the inherent resonant frequency of the machine tool, the vibration upper limit setting unit sets the upper limit value of the vibration parameter to a value smaller than that for other frequencies.

5. The control device for a machine tool according to any one of claims 1 to 4, characterized in that, The vibration condition limiting unit restricts the vibration conditions set by the vibration condition setting unit so that they do not exceed the upper limit of the vibration parameters.

6. A control device for a machine tool, which performs machining while vibrating the tool relative to the workpiece, characterized in that, The control device has: The vibration condition setting unit sets vibration conditions, which include at least one of the following: a frequency parameter consisting of a vibration frequency or a multiple of a vibration frequency, an amplitude parameter consisting of a vibration amplitude or a multiple of a vibration amplitude, and a vibration direction. The vibration upper limit setting unit sets an upper limit value for a vibration parameter determined by the vibration conditions based on the vibration direction. This vibration parameter includes at least one of vibration frequency, vibration amplitude, vibration velocity, vibration acceleration, and vibration jerk. A vibration condition limiting unit, which limits the vibration conditions set by the vibration condition setting unit based on the upper limit value of the vibration parameters; and The vibration control unit controls the vibration of the control shaft according to the vibration conditions limited by the vibration condition limiting unit.

7. The machine tool control device according to claim 6, characterized in that, The vibration upper limit setting unit sets different upper limit values ​​for the vibration parameters when the vibration direction is parallel to and not parallel to the driving direction of each control axis.

8. The machine tool control device according to claim 7, characterized in that, The vibration upper limit setting unit sets the upper limit value of the vibration parameter to decrease or increase in stages or continuously as the inclination of the vibration direction relative to the central axis direction of the workpiece increases.

9. The machine tool control device according to claim 6, characterized in that, The vibration upper limit setting unit sets the upper limit value of the vibration parameter to decrease or increase in stages or continuously as the inclination of the vibration direction relative to the central axis direction of the workpiece increases.

10. The control device for a machine tool according to any one of claims 6 to 9, characterized in that, The vibration condition limiting unit restricts the vibration conditions set by the vibration condition setting unit so that they do not exceed the upper limit of the vibration parameters.

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