Machine tool control device

Abstract

Provided is a control device for a machine tool that machines a workpiece by vibration-controlling a control shaft, wherein shaking of the machine tool as a whole is reliably suppressed. This control device for a machine tool includes: a vibration condition setting unit that sets a vibration condition including at least one of a frequency parameter comprising a vibration frequency or a vibration frequency multiple, an amplitude parameter comprising a vibration amplitude or a vibration amplitude multiple, and a vibration direction; a vibration upper limit setting unit that sets, in accordance with one or both of the vibration frequency and the vibration direction, an upper limit value of the vibration parameter that is determined by the vibration condition and includes at least one of the vibration frequency, the vibration amplitude, a vibration speed, a vibration acceleration, and a vibration jerk; a vibration condition limiting unit that limits, on the basis of the upper limit value of the vibration parameter, the vibration condition set by the vibration condition setting unit; and a vibration control unit that vibration-controls a control shaft on the basis of the vibration condition limited by the vibration condition limiting unit.

Description

[Technical field]

[0001] The present disclosure relates to a control device for a machine tool. [Background technology]

[0002] Conventionally, there is known a control device for a machine tool that processes a workpiece by controlling the axial movement of a control axis while vibrating the control axis, such as in swing cutting, crank pin machining, etc. When the control axis is vibrated in this manner, the vibration may cause excessive shaking of the entire machine tool, which may adversely affect the machining accuracy.

[0003] Therefore, in order to prevent excessive shaking of the entire machine tool due to vibration of the control axis, a technique has been proposed in which upper limits are set for vibration acceleration and jerk, and vibration is controlled within the set upper limits (see, for example, Patent Document 1). This technique is said to ensure a good finished surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-044849 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, due to the influence of the resonance frequency specific to the machine tool and differences in inertia of each control axis, even if an upper limit value for vibration acceleration is set and the vibration acceleration is reduced, the vibration of the entire machine tool may conversely increase. In other words, simply setting an upper limit value for vibration acceleration or jerk without considering the vibration frequency or the inertia of the control axes cannot reliably suppress the vibration of the entire machine tool.

[0006] Therefore, in a control device for a machine tool that performs vibration control on a control axis to machine a workpiece, a technique is desired that can reliably suppress vibration of the entire machine tool. [Means for solving the problem]

[0007] One aspect of the present disclosure is a control device for a machine tool that performs processing while vibrating a tool and a workpiece relative to each other, the control device for the machine tool comprising: a vibration condition setting unit that sets vibration conditions including at least one of a frequency parameter consisting of a vibration frequency or a vibration frequency multiplier, an amplitude parameter consisting of a vibration amplitude or a vibration amplitude multiplier, and a vibration direction; a vibration upper limit setting unit that sets upper limits of vibration parameters including at least one of a vibration frequency, a vibration amplitude, a vibration velocity, a vibration acceleration, and a vibration jerk determined by the vibration conditions, in accordance with one or both of the vibration frequency and the vibration direction; a vibration condition limiting unit that limits the vibration conditions set by the vibration condition setting unit based on the upper limit values ​​of the vibration parameters; and a vibration control unit that performs vibration control of a control axis based on the vibration conditions limited by the vibration condition limiting unit. Effect of the Invention

[0008] According to the present disclosure, in a control device for a machine tool that performs vibration control on a control axis to machine a workpiece, vibrations of the entire machine tool can be reliably suppressed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating a control device for a machine tool according to an embodiment of the present disclosure. [Diagram 2] 11A to 11C are diagrams for explaining vibration control according to the embodiment. [Diagram 3] FIG. 4 is a diagram showing a first example of vibration control according to the embodiment. [Figure 4] FIG. 11 is a diagram showing a second example of vibration control according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0011] Fig. 1 is a diagram showing a machine tool control device 1 according to this embodiment. The machine tool control device 1 according to this embodiment cuts a workpiece with a cutting tool (hereinafter, referred to as tool) by operating at least one spindle that rotates the tool and the workpiece relatively, and at least one feed axis that moves the tool relative to the workpiece. For convenience, Fig. 1 shows only a motor 3 that drives one feed axis.

[0012] The control device 1 of the machine tool according to this embodiment performs oscillating cutting (hereinafter also referred to as vibration cutting) by operating the spindle and feed axis. That is, the control device 1 of the machine tool rotates the tool and the workpiece relatively and performs cutting while oscillating (hereinafter also referred to as vibration) the tool and the workpiece relatively. The tool path, which is the trajectory of the tool, is set so that the current path partially overlaps the previous path, and the part that has been machined on the previous path is included in the current path. Therefore, an air cut occurs in which the cutting edge of the tool separates from the surface of the workpiece, and chips that are continuously generated by cutting are reliably chopped.

[0013] This embodiment can be applied not only to a configuration in which the tool moves in the feed direction while oscillating relative to a workpiece rotating about its central axis, but also to a configuration in which the tool T rotates about the central axis of the workpiece and the workpiece moves in the feed direction relative to the tool. This embodiment can also be applied to both the outer diameter machining and the inner diameter machining of a workpiece. Furthermore, this embodiment can be applied not only to a case in which the workpiece has a tapered portion or an arc-shaped portion on the machining surface and thus requires multiple feed axes (Z-axis and X-axis), but also to a case in which the workpiece is cylindrical or cylindrical and only one specific axis (Z-axis) is sufficient as a feed axis.

[0014] The machine tool control device 1 is configured using a computer including, for example, memories such as a read only memory (ROM) and a random access memory (RAM), a control processing unit (CPU), and a communication control unit, all of which are connected via a bus. As shown in Fig. 1, 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, and the functions and operations of these units can be achieved by cooperation between the CPU and memory mounted on the computer, and a control program stored in the memory.

[0015] A host computer (not shown), such as a CNC (Computer Numerical Controller) or a PLC (Programmable Logic Controller), is connected to the machine tool control device 1. Machining programs and workpiece machining conditions, such as rotation speed and feed speed, are input to the machine tool control device 1 from these host computers.

[0016] The machining conditions of the workpiece include the relative rotation speed of the workpiece and the tool around the central axis of the workpiece, the relative feed speed of the tool and the workpiece, and a position command for the feed axis, etc. In this embodiment, the CPU in the control device 1 of the machine tool may be configured to read out the rotation speed and feed speed from the input machining program as machining conditions and output them to the vibration control unit 14, or a position command creation unit in the vibration control unit 14, etc. may be provided in the above-mentioned upper computer.

[0017] The vibration condition setting unit 11 sets vibration conditions including at least one of a frequency parameter consisting of a vibration frequency or a vibration frequency multiplier, an amplitude parameter consisting of a vibration amplitude or a vibration amplitude multiplier, and a vibration direction. The vibration condition setting unit 11 sets the vibration conditions based on a machining program, machining conditions, etc. input to the control device 1 of the machine tool, under restrictions imposed by a vibration condition restriction unit 12 described below. The vibration conditions set by the vibration condition setting unit 11 are output to a vibration control unit 14 described below.

[0018] Here, the vibration frequency magnification is a frequency parameter obtained by dividing the vibration frequency by the spindle speed. The vibration amplitude magnification is an amplitude parameter obtained by dividing the vibration amplitude by half the feed amount of the feed axis per one spindle revolution. The vibration direction is represented by, for example, the inclination θ with respect to the central axis of the workpiece (Z-axis direction) (see Fig. 4 described later).

[0019] The vibration upper limit setting unit 13 sets the upper limit of the vibration parameters including at least one of the vibration frequency, vibration amplitude, vibration velocity, vibration acceleration, and vibration jerk determined by the vibration conditions, according to one or both of the vibration frequency and the vibration direction. The upper limit of the vibration parameters set by the vibration upper limit setting unit 13 is output to the vibration condition restriction unit 12 described later.

[0020] When the vibration upper limit setting unit 13 sets the upper limit value of the vibration parameter according to the vibration frequency, it is preferable to set the upper limit value of the vibration parameter so that it decreases stepwise or continuously as the vibration frequency increases. This is because the higher the vibration frequency, the more likely the machine tool is to shake. For example, the vibration upper limit setting unit 13 sets the upper limit value of the vibration parameter, such as the acceleration upper limit, so that it decreases as the vibration frequency increases in 10 Hz intervals, such as 0 to 10 Hz, 10 to 20 Hz, 20 to 30 Hz, etc. (see FIG. 3 described later).

[0021] The vibration of the entire machine tool caused by vibration control of the control axis is caused by the frequency, amplitude, speed, acceleration, and jerk of the vibration. These vibration amplitude, speed, acceleration, and jerk are affected by the vibration frequency. In this embodiment, on the other hand, the upper limit values ​​of vibration parameters such as the vibration frequency, vibration amplitude, vibration velocity, vibration acceleration, and vibration jerk are set according to the vibration frequency, and the vibration conditions are set based on the upper limit values ​​of the vibration parameters set in this way, thereby effectively suppressing the vibration of the entire machine tool.

[0022] When the vibration frequency corresponds to a resonant frequency inherent to the machine tool, it is more preferable that the vibration upper limit setting unit 13 sets the upper limit value of the vibration parameter to a smaller value than in the case of other frequencies. For example, when the resonant frequency inherent to the machine tool is 40 to 50 Hz, the vibration upper limit setting unit 13 sets the upper limit value of the vibration parameter to a smaller value than in the case of other vibration frequencies that are less than 40 Hz or more than 50 Hz.

[0023] When the vibration frequency in the vibration control of the control axis corresponds to the resonant frequency inherent to the machine tool, the machine tool vibrates more strongly in synchronization with the vibration of the control axis. In contrast, in this embodiment, when the vibration frequency corresponds to the resonant frequency, the upper limit value of the vibration parameter is set smaller, and the vibration condition is set based on the upper limit value of the vibration parameter set in this way, so that the vibration of the entire machine tool is more effectively suppressed.

[0024] In addition, when the vibration frequency corresponds to the resonant frequency, the resonant frequency inherent to the machine tool may be included in a vibration frequency band having a certain width, for example, a width of 10 Hz. In this case, the width of the vibration frequency band is set appropriately.

[0025] In some cases, it may be preferable for the vibration upper limit setting unit 13 to set the upper limit values ​​of the vibration parameters so that they decrease stepwise or continuously as the inclination of the vibration direction with respect to the central axis direction of the workpiece increases. In this case, for example, the upper limit values ​​of the vibration parameters such as the acceleration upper limit are set so that the inclination θ of the rocking direction (hereinafter also referred to as the vibration direction) with respect to the central axis line (Z-axis direction) of the workpiece increases in 10° intervals, such as 0° to 10°, 10° to 20°, and 20° to 30° (see FIG. 4 described later).

[0026] For example, heavy objects such as servo motors are often arranged in the X-axis direction (radial direction of the workpiece) perpendicular to the Z-axis direction (center axis direction of the workpiece), so the vibration amount of the control axis is larger in the X-axis than in the Z-axis, and the inertia is larger. Since the inertia of the control axis differs depending on the machine tool, the vibration of the entire machine tool caused when the control axis is vibrated is affected by the vibration direction that represents the ratio of the vibration amount of the control axis. In contrast, in this embodiment, the upper limit values ​​of vibration parameters such as vibration acceleration and vibration jerk are set according to the vibration direction, specifically based on the inclination θ of the vibration direction with respect to the Z-axis, so that the vibration conditions are set based on the upper limit values ​​of the vibration parameters set in this way, and therefore the vibration of the entire machine tool is more effectively suppressed.

[0027] Of course, the magnitude of inertia of the Z-axis and X-axis differs depending on the machine configuration, so there are cases where the Z-axis has greater inertia than the X-axis. In this case, the vibration of the entire machine tool can be more effectively suppressed by setting the tilt θ of the vibration direction in 10° increments, such as 0° to 10°, 10° to 20°, and 20 to 30°, so that the upper limit values ​​of vibration parameters such as the upper acceleration limit value increase as the tilt θ of the vibration direction with respect to the Z-axis direction increases.

[0028] Furthermore, it is preferable that the vibration upper limit setting unit 13 sets the upper limit value of the vibration parameter to a different value when the vibration direction is parallel to the drive direction of each control axis and when it is non-parallel. When the vibration direction is parallel to the drive direction of each control axis, it means that only one of the control axes is vibrated, and when it is non-parallel, it means that multiple drive axes are vibrated in coordination. That is, it is preferable to set the upper limit value of the vibration parameter when multiple drive axes are vibrated in coordination, separately from the upper limit value of the vibration parameter for each control axis. This may more effectively suppress the vibration of the entire machine tool.

[0029] Furthermore, when the upper limit value of the vibration parameter is set according to the vibration direction, the vibration upper limit setting unit 13 may set the vibration frequency as the upper limit value of the vibration parameter. In this case, since the vibration frequency increases, the shaking of the machine tool also increases, it is preferable to set the upper limit value of the vibration frequency to be smaller as the inclination of the vibration direction relative to the central axis direction of the workpiece increases.

[0030] The vibration upper limit setting unit 13 can measure the vibration of the machine tool when vibration control of the control axis is actually performed in advance, not only by visual inspection by the user but also by various sensors, etc., and determine the upper limit value of the vibration parameter based on these results.

[0031] The vibration condition restriction unit 12 restricts the vibration conditions set by the vibration condition setting unit 11 based on the upper limit value of the vibration parameter set by the vibration upper limit setting unit 13. Specifically, the vibration condition restriction unit 12 acquires a frequency parameter and a vibration direction from the vibration condition setting unit 11, and restricts the vibration conditions using the upper limit value of the vibration parameter corresponding to the acquired frequency parameter and vibration direction.

[0032] It is preferable that the vibration condition limiting unit 12 limits the vibration conditions set by the vibration condition setting unit 11 so as not to exceed the upper limit value of the vibration parameter corresponding to the acquired frequency parameter or vibration direction. For example, the vibration condition limiting unit 12 clamps the vibration frequency, vibration amplitude, etc. within a range not exceeding the upper limit value of the vibration parameter. Alternatively, when the upper limit value of the vibration parameter is exceeded, the vibration condition limiting unit 12 issues an alarm (warning) or the like to stop the machining program.

[0033] The vibration control unit 14 performs vibration control of the control axis based on the vibration conditions set by the vibration condition setting unit 11 under the restriction by the vibration condition restriction unit 12. In order to execute vibration control of the control axis, the vibration control unit 14 includes various functional units (none of which are shown), such as a position command generation unit, a vibration command generation unit, a superposition command generation unit, a learning control unit, and a position and speed control unit.

[0034] The position command generating unit generates a position command as a movement command for the motor 3 based on the machining program and machining conditions inputted to the control device 1 of the machine tool. Specifically, the position command creating unit generates a position command (movement command) for each feed axis based on the relative rotation speed of the workpiece and the tool around the central axis of the workpiece and the relative feed speed of the tool and the workpiece.

[0035] The vibration command generating unit generates a vibration command based on the vibration conditions set by the vibration condition setting unit 11 described above.

[0036] The superimposed command generating unit calculates a position deviation, which is the difference between the position feedback based on the position detection by the encoder of the motor 3 of the feed axis and the position command, and generates a superimposed command by superimposing the vibration command generated by the vibration command generating unit on the calculated position deviation. Alternatively, the vibration command may be superimposed on the position command instead of the position deviation.

[0037] The learning control unit calculates a correction amount of the superimposition command based on the superimposition command, and corrects the superimposition command by adding the calculated correction amount to the superimposition command. The learning control unit has a memory, correlates the vibration phase and the correction amount within one or multiple vibration periods, and stores them in the memory. The learning control unit reads out the superimposition command stored in the memory at a timing when the phase delay of the vibration operation according to the responsiveness of the motor 3 can be compensated for, and outputs the superimposition command as a correction amount. If the vibration phase for which the correction amount is output does not exist in the vibration phases stored in the memory, the correction amount to be output may be calculated from a correction amount close to the vibration phase. Generally, the higher the vibration frequency, the larger the position deviation with respect to the vibration command. Therefore, by performing this correction by the learning control unit, it is possible to improve the followability to the periodic vibration command.

[0038] The position and speed control unit generates a torque command for the motor 3 that drives the feed axis based on the superimposed command after the correction amount is added, and controls the motor 3 by the generated torque command. As a result, machining is performed while vibrating the tool T and the workpiece W relatively.

[0039] The display unit 15 displays on a display screen the upper limit values ​​of the vibration parameters set by the vibration upper limit setting unit 13 and the vibration conditions limited by the vibration condition limiting unit 12 based on the upper limit values ​​and set by the vibration condition setting unit 11. The display unit 15 also displays various setting parameters as well as the machining program inputted to the control device 1 of the machine tool. This allows the user to set the upper limit values ​​of the vibration parameters and the vibration conditions by an input unit (not shown) while checking the display screen.

[0040] Next, vibration control of a control axis executed by the control device 1 for a machine tool according to this embodiment will be described.

[0041] 2 is a diagram for explaining vibration control according to the present embodiment. As shown in FIG. 2, for example, when the vibration acceleration is 1,800,000 [mm / min 2 There are multiple combinations of vibration frequency and vibration amplitude that satisfy the condition 1. In FIG. 2, three patterns, 1 to 3, are shown as examples, and the vibration acceleration determined by the vibration conditions of patterns 1 to 3 is 1,800,000 [mm / min 2 This vibration acceleration is calculated by the following formula (1). [Number 1] Vibration acceleration = α × (vibration amplitude) × (vibration frequency) 2 ...Equation (1)

[0042] Here, as shown in the display unit 15 in FIG. 2, the upper vibration limit setting unit 13 sets the upper acceleration limit to 1,800,000 [mm / min 2 ], and the vibration frequency and vibration amplitude specified by the machining program are 40 Hz and 0.2 mm. In this case, as is clear from a comparison with pattern 1, which has a vibration frequency of 40 Hz and a vibration amplitude of 0.015 mm, the vibration acceleration calculated by the above formula (1) is the upper limit value of 1,800,000 [mm / min 2 This causes large vibrations in the entire machine tool.

[0043] Therefore, in this embodiment, the vibration condition limiting unit 12 limits the vibration acceleration to the upper limit of 1,800,000 [mm / min 2 For example, the vibration frequency is kept at 40 Hz and the vibration amplitude is clamped at 0.015 mm so that the vibration acceleration does not exceed the upper limit of 1,800,000 [mm / min.]. The vibration condition setting unit 11 then sets the vibration frequency of 40 Hz and the clamped vibration amplitude of 0.015 mm as the vibration conditions. 2 ], which reliably suppresses vibrations that occur throughout the entire machine tool.

[0044] It should be noted that the clamping is not limited to the vibration amplitude, but the vibration frequency may be clamped, or both the vibration amplitude and the vibration frequency may be clamped. The method of limiting the vibration conditions is not limited to clamping, and may be configured to issue an alarm or the like and stop the machining program when a vibration parameter such as vibration acceleration exceeds its upper limit.

[0045] Fig. 3 is a diagram showing a first example of vibration control according to this embodiment. The first example shown in Fig. 3 is an example in which the upper limit of vibration acceleration is set according to the vibration frequency. Specifically, as shown on display unit 15 in Fig. 3, the upper limit of vibration acceleration when the vibration frequency is 0 Hz to 10 Hz (meaning 0 or more and less than 10; the same applies below) is set to 2,000,000 [mm / min 2 ], and 1,900,000 [mm / min at 10 to 20 Hz 2 ], and 1,800,000 [mm / min at 20-30Hz 2 ], and 1,600,000 [mm / min at 30-40Hz 2 ], and 1,000,000 [mm / min for 40-50Hz 2 ], and 1,500,000 [mm / min at 50-60Hz 2 As shown in FIG. 1, an upper limit of vibration acceleration is set for each vibration frequency band at 10 Hz intervals. In this first example, a lower upper limit of acceleration is set as the vibration frequency increases, and the smallest upper limit of acceleration is set at 40 to 50 Hz, which corresponds to the resonant frequency of the machine tool.

[0046] In this first example, as shown on the display unit 15 in Fig. 3, the vibration frequency of the vibration cutting specified by the machining program inputted to the control device 1 of the machine tool is 25 Hz and the vibration amplitude is 0.1 mm. When the vibration acceleration at a vibration frequency of 25 Hz and a vibration amplitude of 0.1 mm is calculated using the above-mentioned formula (1), the upper limit of the vibration acceleration at a vibration frequency of 25 Hz is 1,800,000 [mm / min 2 ]. Therefore, in this first example, the vibration amplitude is changed to a smaller value while keeping the vibration frequency at 25 Hz, and when the calculated vibration acceleration does not exceed the vibration acceleration upper limit, the vibration amplitude is clamped to 0.00384 mm, which is the vibration amplitude at that time. In this way, by setting vibration conditions that do not exceed the vibration acceleration upper limit, vibrations occurring in the entire machine tool are reliably suppressed.

[0047] Fig. 4 is a diagram showing a second example of vibration control according to this embodiment. The second example shown in Fig. 4 is an example in which the upper limit of vibration acceleration is set according to the vibration direction. Specifically, as shown on the display unit 15 in Fig. 4, when the inclination θ of the vibration direction with respect to the Z axis is 0° to 10° (or less; the same applies below), the upper limit of vibration acceleration is set to 2000000 [mm / min 2 ], 1900000 [mm / min for 10-20° 2 ], 1,800,000 [mm / min when 20~30° 2 ], 1600000 [mm / min for 30-40° 2 ], and 1,400,000 [mm / min.] for 40 to 50° 2 ], and 1,100,000 [mm / min.] for 50 to 60° 2 As shown in the second example, the upper limit of vibration acceleration is set for each inclination angle band at 10° intervals. Also, in this second example, the upper limit of acceleration is set smaller as the inclination of the vibration direction with respect to the Z axis increases.

[0048] In this second example, as shown on the display unit 15 in FIG. 4, the vibration frequency of the vibration cutting specified by the machining program inputted to the control device 1 of the machine tool is 25 Hz, and the vibration amplitude is 0.04 mm. The movement direction of the movement command specified by the machining program is determined to be 45° from the X coordinate position and Z coordinate position specified by G00 and G01. Here, in the vibration cutting in this example, since the vibration direction is the same as the movement direction of the movement command, the inclination θ of the vibration direction relative to the Z axis is 45°. When the vibration acceleration at a vibration frequency of 25 Hz and a vibration amplitude of 0.04 mm is calculated using the above-mentioned formula (1), the upper limit of the vibration acceleration when the inclination θ of the vibration direction relative to the Z axis is 1,400,000 [mm / min] is obtained. 2 ]. Therefore, in this second example, the vibration amplitude is changed to a smaller value while keeping the vibration frequency at 25 Hz, and when the calculated vibration acceleration does not exceed the vibration acceleration upper limit, the vibration amplitude is clamped to 0.0299 mm, which is the vibration amplitude at that time. In this way, by setting vibration conditions that do not exceed the vibration acceleration upper limit, vibrations occurring in the entire machine tool are reliably suppressed.

[0049] According to this embodiment, the following effects are achieved.

[0050] The control device 1 of the machine tool according to this embodiment includes a vibration condition setting unit 11 that sets vibration conditions including at least one of a frequency parameter consisting of a vibration frequency or a vibration frequency multiplier, an amplitude parameter consisting of a vibration amplitude or a vibration amplitude multiplier, and a vibration direction, and a vibration upper limit setting unit 13 that sets an upper limit value of a vibration parameter including at least one of a vibration frequency, a vibration amplitude, a vibration velocity, a vibration acceleration, and a vibration jerk determined by the vibration conditions, in accordance with one or both of the vibration frequency and the vibration direction. The control device 1 of the machine tool according to this embodiment also includes a vibration condition limiting unit 12 that limits the vibration conditions set by the vibration condition setting unit 11 based on the upper limit value of the vibration parameter, and a vibration control unit 14 that performs vibration control of a control axis based on the vibration conditions limited by the vibration condition limiting unit 12.

[0051] The vibration of the entire machine tool caused by vibration control of the control axis is mainly caused by vibration parameters such as vibration acceleration and jerk, and these vibration parameters are affected by the vibration frequency and vibration direction. In contrast, according to this embodiment, the vibration conditions set by the vibration condition setting unit 11 are restricted by the vibration condition restriction unit 12 based on the upper limit values ​​of the vibration parameters set by the vibration upper limit setting unit 13 according to one or both of the vibration frequency and the vibration direction. Therefore, in the vibration control of the control axis, it is possible to set vibration conditions that do not exceed the upper limit values ​​of the vibration parameters set according to the vibration frequency and the vibration direction, and it is possible to reliably suppress the vibration occurring in the entire machine tool.

[0052] Furthermore, the vibration upper limit setting unit 13 of this embodiment sets the upper limit value of the vibration parameter so that it decreases stepwise or continuously as the vibration frequency increases. The higher the vibration frequency, the more likely the machine tool is to shake. According to this embodiment, since a more appropriate upper limit value of the vibration parameter can be set according to the vibration frequency, it is possible to more reliably suppress the vibration occurring in the entire machine tool.

[0053] Furthermore, the vibration upper limit setting unit 13 of this embodiment sets the upper limit of the vibration parameters to different values ​​when the vibration direction is parallel to the drive direction of each control axis and when it is not parallel to the drive direction of each control axis. This can more effectively suppress vibration of the entire machine tool.

[0054] Furthermore, the vibration upper limit setting unit 13 of this embodiment sets the upper limit value of the vibration parameter to be smaller or larger in a stepwise or continuous manner as the inclination θ of the vibration direction relative to the central axis direction (Z axis) of the workpiece increases. Depending on the mechanical configuration, the machine tool becomes more likely or less likely to shake as the inclination θ of the vibration direction relative to the central axis direction (Z axis) of the workpiece increases, but according to this embodiment, a more appropriate upper limit value of the vibration parameter can be set according to the vibration direction, so that the vibration occurring in the entire machine tool can be more reliably suppressed.

[0055] Furthermore, the vibration upper limit setting unit 13 of this embodiment sets the upper limit value of the vibration parameter to a smaller value when the vibration frequency corresponds to a resonant frequency specific to the machine tool, compared to the case of other frequencies. When the vibration frequency corresponds to the resonant frequency of the machine tool, the machine tool is prone to shaking, but according to this embodiment, a more appropriate upper limit value of the vibration parameter can be set according to the resonant frequency, so that shaking occurring in the entire machine tool can be more reliably suppressed.

[0056] Furthermore, in this embodiment, the vibration condition limiting unit 12 limits the vibration conditions set by the vibration condition setting unit 11 so as not to exceed the upper limit value of the vibration parameter. As a result, according to this embodiment, it is possible to reliably avoid exceeding the upper limit value of the vibration parameter, and therefore it is possible to more reliably suppress vibrations occurring in the entire machine tool.

[0057] The present disclosure is not limited to the above-described aspects, and modifications and improvements within the scope that can achieve the object of the present disclosure are included in the present disclosure.

[0058] For example, in the above embodiment, the present invention is applied to vibration cutting, but is not limited thereto. The present invention can also be applied to a control device of a machine tool that processes a workpiece by controlling the axial movement while vibrating the control axis, such as in crank pin processing, and can obtain the same effects as those of the above embodiment.

[0059] In the above embodiment, the upper limit value of the vibration parameter is set according to the vibration frequency and the vibration direction, but the present invention is not limited to this. The upper limit value of the vibration parameter may be set according to both the vibration frequency and the vibration direction.

[0060] In the above embodiment, the control device 1 of the machine tool is configured to include the display unit 15, but this is not limited to the above. The control device 1 of the machine tool does not have to include the display unit 15, and the display unit 15 may be provided in the above-mentioned higher-level computer or the like. [Explanation of symbols]

[0061] 1. Machine tool control device 3 Motor 11 Vibration condition setting section 12 Vibration condition restriction section 13. Upper limit vibration setting section 14 Vibration control section 15 Display section

Claims

1. A control device for a machine tool that performs machining while vibrating a tool and a workpiece relative to each other, a vibration condition setting unit that sets vibration conditions including at least one of a frequency parameter consisting of a vibration frequency or a vibration frequency magnification, an amplitude parameter consisting of a vibration amplitude or a vibration amplitude magnification, and a vibration direction; a vibration upper limit setting unit that sets an upper limit value of a vibration parameter including at least one of a vibration amplitude, a vibration velocity, a vibration acceleration, and a vibration jerk, which is determined by the vibration conditions, in accordance with a vibration frequency; a vibration condition limiting unit that limits the vibration condition set by the vibration condition setting unit based on an upper limit value of the vibration parameter; a vibration control unit that controls vibration of a control axis based on the vibration conditions restricted by the vibration condition restriction unit.

2. A control device for a machine tool that performs machining while vibrating a tool and a workpiece relative to one another, comprising: a vibration condition setting unit that sets vibration conditions including at least one of a frequency parameter consisting of a vibration frequency or a vibration frequency magnification, an amplitude parameter consisting of a vibration amplitude or a vibration amplitude magnification, and a vibration direction; a vibration upper limit setting unit that sets an upper limit value of a vibration parameter including at least one of a vibration frequency, a vibration amplitude, a vibration velocity, a vibration acceleration, and a vibration jerk, which is determined by the vibration conditions, in accordance with a vibration direction; a vibration condition limiting unit that limits the vibration condition set by the vibration condition setting unit based on an upper limit value of the vibration parameter; a vibration control unit that controls vibration of a control axis based on the vibration conditions restricted by the vibration condition restriction unit.

3. A control device for a machine tool as described in claim 1, wherein the vibration upper limit setting unit sets the upper limit value of the vibration parameter so that it decreases gradually or continuously as the vibration frequency increases.

4. A control device for a machine tool as described in Claim 2, wherein the vibration upper limit setting unit sets the upper limit value of the vibration parameter to different values ​​when the vibration direction is parallel to the drive direction of each control axis and when it is non-parallel.

5. A control device for a machine tool as described in claim 2 or 4, wherein the vibration upper limit setting unit sets the upper limit value of the vibration parameter to be gradually or continuously smaller or larger as the inclination of the vibration direction relative to the central axis direction of the workpiece increases.

6. A control device for a machine tool as described in claim 1 or 3, wherein the vibration upper limit setting unit sets the upper limit value of the vibration parameter to a smaller value when the vibration frequency corresponds to a resonant frequency specific to the machine tool compared to the cases of other frequencies.

7. A control device for a machine tool described in any one of claims 1 to 6, wherein the vibration condition limiting unit limits the vibration conditions set by the vibration condition setting unit so as not to exceed an upper limit value of the vibration parameter.

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