Control device for machine tool

Abstract

Provided is a technology with which a chip length can be calculated, and with which a machining condition and an oscillation condition can be set easily while checking the calculated chip length. A control device 1 of a machine tool which performs machining while causing a cutting tool and a workpiece to oscillate relative to one another comprises: a condition acquiring unit 12 for acquiring a machining condition and an oscillation condition; a chip length calculating unit 13 for calculating a chip length on the basis of the machining condition and the oscillation condition acquired by the condition acquiring unit 12; and a chip length outputting unit 14 for outputting the chip length calculated by the chip length calculating unit 13.

Description

Machine tool control device

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

[0002] Conventionally, to prevent chips continuously generated during cutting from becoming entangled in the workpiece or cutting tool, which can cause machining defects or machine failures, a known method is oscillation cutting, in which the cutting tool and workpiece are oscillated relative to each other while cutting the workpiece. In this oscillation cutting, the tool path, which is the trajectory of the cutting tool, is set to partially overlap the previous tool path by adjusting the oscillation frequency and oscillation amplitude. This causes a missed cut, called an air cut, in which the cutting edge of the cutting tool separates from the surface of the workpiece, shredding the chips.

[0003] Even if the chips can be cut into small pieces, if the chips are too long, they may become tangled in the workpiece or cutting tool. Also, if the cutting tool or workpiece is oscillated excessively in order to shorten the chip length, the load on the machine increases, which may cause the machine to break down.

[0004] For example, as a technology that takes chip length into consideration, a technology has been proposed in which the number of vibrations (swings) is determined based on a set chip length and the diameter of the workpiece (see, for example, Patent Document 1). This technology is said to be able to automatically determine the number of vibrations based on a set desired chip length and the diameter of the workpiece.

[0005] Patent No. 6744815

[0006] However, in the technology of Patent Document 1, the desired chip length is simply calculated from the number of vibrations, but the chip length depends on the machining conditions and oscillation conditions, and it is difficult to set the machining conditions and oscillation conditions while taking the chip length into consideration. Therefore, a technology that can calculate the chip length and easily set the machining conditions and oscillation conditions while checking the calculated chip length is desired.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a technology that can calculate chip length and easily set machining conditions and oscillation conditions while checking the calculated chip length.

[0008] The present disclosure relates to a control device for a machine tool that performs processing while swinging a cutting tool and a workpiece relative to one another, the control device for a machine tool including: a condition acquisition unit that acquires processing conditions and swing conditions; a chip length calculation unit that calculates a chip length based on the processing conditions and the swing conditions acquired by the condition acquisition unit; and a chip length output unit that outputs the chip length calculated by the chip length calculation unit.

[0009] According to the present disclosure, it is possible to provide a technology that can calculate chip length and easily set machining conditions and oscillation conditions while checking the calculated chip length.

[0010] 1 is a diagram for explaining swing cutting. It is a functional block diagram of a control device of a machine tool according to a first embodiment. It is a diagram showing a chip length confirmation screen into which machining conditions and swing conditions are input. It is a diagram showing a cutting path. It is a diagram showing a chip length confirmation screen on which a calculated chip length is displayed. It is a functional block diagram of a control device of a machine tool according to a second embodiment. It is a diagram showing a first example of a chip length correction table. It is a diagram showing a first example of a chip length correction table. It is a diagram showing a chip length confirmation screen on which a calculated chip length is displayed. It is a diagram showing a chip length confirmation screen on which a chip length corrected based on a chip length correction coefficient is displayed. It is a diagram showing a second example of a chip length correction table. It is a diagram showing a chip length confirmation screen on which a calculated chip length is displayed. It is a diagram showing a chip length confirmation screen on which a chip length corrected for each type of workpiece is displayed. It is a functional block diagram of a control device of a machine tool according to a third embodiment. It is a diagram showing a attenuation rate of an actual measured value with respect to a command value of swing amplitude. It is a diagram showing a chip length confirmation screen into which a attenuation rate of swing amplitude is input. FIG. 10 is a diagram showing a chip length confirmation screen on which the chip length corrected based on the attenuation rate of the oscillation amplitude is displayed.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description of the second and subsequent embodiments, the same reference numerals will be used to designate components common to the first and second embodiments, and the description thereof will be omitted as appropriate.

[0012] First Embodiment A machine tool control device according to a first embodiment performs swing cutting, which cuts a workpiece while swinging the cutting tool and the workpiece relative to each other. FIG. 1 is a diagram illustrating swing cutting. In the example of swing cutting shown in FIG. 1 , at least one spindle S that rotates the cutting tool T and the workpiece W relative to each other and at least one feed axis (not shown) that moves the cutting tool T relative to the workpiece W are operated to rotate the cutting tool T and the workpiece W relative to each other and swing the cutting tool T and the workpiece W relative to each other in the feed direction to perform cutting. At this time, the tool path, which is the trajectory of the cutting tool T, is set so that the current path partially overlaps the previous path. In other words, because the current path partially includes a portion already machined in the previous path, a missed cut known as an air cut occurs, in which the cutting edge of the cutting tool T separates from the surface of the workpiece W, shredding chips.

[0013] The shape of the workpiece is not limited in the swing cutting performed in this embodiment. That is, it can be applied to cases where the workpiece has a tapered portion or an arc-shaped portion on the machining surface, requiring multiple feed axes (Z-axis and X-axis), or to cases where the workpiece is columnar or cylindrical and only one specific feed axis (Z-axis) is sufficient.

[0014] Figure 2 is a functional block diagram of the machine tool control device 1 according to the first embodiment. As shown in Figure 2, the machine tool control device 1 according to the first embodiment includes an input unit 11, a condition acquisition unit 12, a chip length calculation unit 13, a chip length output unit 14, and a chip length display unit 15. The machine tool control device 1 is configured using a computer including memories such as a ROM (read only memory) and a RAM (random access memory), a CPU (control processing unit), and a communication control unit, which are connected to each other via a bus, for example. The functions and operations of the above functional units are achieved by cooperation between the CPU and memory installed in the computer, and a control program stored in the memory.

[0015] The machine tool control device 1 may be configured with a CNC (Computer Numerical Controller), and may be connected to a host computer (not shown) such as a CNC or a PLC (Programmable Logic Controller). In addition to a machining program, machining conditions such as rotation speed and feed rate, and oscillation conditions such as oscillation amplitude and oscillation frequency are input to the machine tool control device 1 from the host computer.

[0016] The input unit 11 inputs information about the machining conditions and the oscillation conditions in response to an operator's input operation on an input means (not shown), such as a keyboard or a touch panel. The information about the machining conditions and the oscillation conditions input by the input unit 11 is output to the condition acquisition unit 12, which will be described later.

[0017] The condition acquisition unit 12 acquires the machining conditions and oscillation conditions input by the input unit 11. The condition acquisition unit 12 outputs the acquired machining conditions and oscillation conditions to the chip length calculation unit 13, which will be described later.

[0018] Here, the machining conditions include at least information regarding the machining diameter (mm), as well as information regarding, for example, the number of revolutions S (1 / min) of the spindle, the feed rate F (mm / rev), the feed rate of the cutting tool (mm / min), the workpiece diameter (mm), the cutting edge R (mm), and the clearance angle (°) of the cutting tool.

[0019] The oscillation conditions include information regarding the relative oscillation frequency per rotation between the cutting tool and the workpiece, and information regarding the oscillation amplitude relative to the relative feed rate per rotation between the cutting tool and the workpiece. The information regarding the relative oscillation frequency per rotation between the cutting tool and the workpiece includes an oscillation frequency magnification I (times), which indicates the oscillation frequency per rotation of the spindle. The information regarding the oscillation amplitude relative to the relative feed rate per rotation between the cutting tool and the workpiece includes an oscillation amplitude magnification K (times), which indicates the magnitude of the oscillation amplitude relative to the magnitude of the feed rate per rotation of the spindle. The oscillation frequency magnification I (times) may be specified directly, or may be calculated from the oscillation frequency (Hz) and the spindle rotation speed S (1 / min) after specifying the oscillation frequency (Hz). Similarly, the oscillation amplitude magnification K (times) may be specified directly, or may be calculated from the oscillation amplitude (mm) and the feed rate F (mm / rev) after specifying the oscillation amplitude (mm).

[0020] The chip length calculation unit 13 calculates the chip length based on the machining conditions and swing conditions acquired by the condition acquisition unit 12. A specific method for calculating the chip length will be described in detail later.

[0021] The chip length output unit 14 outputs to the outside the chip length calculated by the chip length calculation unit 13. In this embodiment, the chip length output unit 14 outputs the calculated chip length to a chip length display unit 15, which will be described later.

[0022] The chip length display unit 15 displays the chip length output by the chip length output unit 14. Specifically, the chip length display unit 15 displays the chip length calculated by the chip length calculation unit 13 on a chip length confirmation screen, which will be described in detail later.

[0023] Next, a method for calculating the chip length by the chip length calculation unit 13 will be described in detail with reference to Figs. 3 to 5. Fig. 3 is a diagram showing a chip length confirmation screen in which the machining conditions and oscillation conditions are input. Fig. 4 is a diagram showing the cutting path. Fig. 5 is a diagram showing the chip length confirmation screen in which the calculated chip length is displayed.

[0024] As shown in Fig. 3, first, the operator inputs the machining conditions and the oscillation conditions by operating the input means of the input unit 11 using the chip length confirmation screen of the chip length display unit 15. For example, as in the example shown in Fig. 3, the operator inputs a coordinate value in the workpiece radial direction (also referred to as coordinate value X), which is information related to the machining diameter, as the machining condition, and also inputs an oscillation frequency magnification I and an oscillation amplitude magnification K, which are oscillation conditions.

[0025] The input machining conditions and oscillation conditions are then acquired by the condition acquisition unit 12, and the chip length calculation unit 13 automatically calculates the chip length based on the acquired machining conditions and oscillation conditions. Specifically, the chip length calculation unit 13 calculates the coordinate value Y (mm) in the feed direction of the cutting pass using the following formula (1), and searches for the point where the phase difference between the intersections of the cutting passes (the previous cutting pass and the current cutting pass) is maximum.

[0026]

[0027] In formula (1), Y represents the coordinate value in the feed direction (mm), f represents the feed amount per rotation of the spindle (mm / rev), S represents the number of rotations of the spindle (1 / min), I represents the oscillation frequency magnification (times), K represents the oscillation amplitude magnification (times), and t represents time (sec).

[0028] Here, as shown in Figure 4, the intersection of the previous cutting pass and the current cutting pass is the start or end point of air cutting. In other words, the point where the phase difference between the intersection of the previous cutting pass and the current cutting pass is maximum means the cutting section with the maximum chip length, where the chip length is maximum. Therefore, in this embodiment, the phase difference of this cutting section with the maximum chip length is calculated using the above formula (1), and the maximum chip length obtained by multiplying the phase difference of the cutting section with the maximum chip length by the workpiece radius (mm) as shown in the following formula (2) is calculated as the chip length (mm). Hereinafter, in this specification, the maximum chip length and the chip length will be described as being synonymous.

[0029]

[0030] As is clear from the above-described chip length calculation method, the chip length calculated by the chip length calculation unit 13 of this embodiment excludes sections where air cutting occurs, and the sections where air cutting occurs are not included in the chip length. In contrast, in conventional chip length calculations, where r is the workpiece radius (mm) and I is the oscillation frequency magnification (times), the chip length (mm) is calculated as 2πr / I, and the sections where air cutting occurs are also included in the chip length. Therefore, the chip length calculation unit 13 of this embodiment can calculate chip lengths more accurately than conventional methods.

[0031] The chip length calculated by the chip length calculation unit 13 as described above is automatically displayed on a chip length confirmation screen as shown in Fig. 5. This allows the operator to set the machining conditions and oscillation conditions while checking the chip length that has been calculated more accurately than before, making it easier to set the machining conditions and oscillation conditions.

[0032] The machine tool control device 1 according to the first embodiment provides the following effects.

[0033] The machine tool control device 1 according to this embodiment is provided with a condition acquisition unit 12 that acquires machining conditions and oscillation conditions, a chip length calculation unit 13 that calculates chip length based on the machining conditions and oscillation conditions, and a chip length output unit 14 that outputs the calculated chip length. As a result, while chip length depends on the machining conditions and oscillation conditions and it has conventionally been difficult to set machining conditions and oscillation conditions while taking chip length into consideration, according to this embodiment, chip length can be calculated based on the machining conditions and oscillation conditions, and machining conditions and oscillation conditions can be easily set while checking the calculated chip length that has been output to an external device, etc.

[0034] Furthermore, the machine tool control device 1 according to this embodiment is further provided with a chip length display unit 15 that displays the chip length output by the chip length output unit 14. This allows the operator to more easily set the machining conditions and oscillation conditions while checking the chip length displayed on a display screen or the like by the chip length display unit 15.

[0035] Furthermore, the machine tool control device 1 according to this embodiment is configured to acquire information on the machining diameter as the machining conditions, and acquire information on the relative number of oscillations per rotation between the cutting tool and the workpiece, and information on the oscillation amplitude for the relative feed rate per rotation between the cutting tool and the workpiece, as oscillation conditions, and calculate the chip length based on these machining conditions and oscillation conditions. As a result, although chip length depends on oscillation amplitude, which has a significant impact on the occurrence of air cut, in the past oscillation amplitude was not taken into consideration, but according to this embodiment, chip length can be calculated by including oscillation amplitude in the calculation conditions, and a more accurate chip length can be calculated by excluding the section where air cut occurs.

[0036] [Second embodiment] Figure 6 is a functional block diagram of a machine tool control device 1A according to a second embodiment. As shown in Figure 6, the machine tool control device 1A according to the second embodiment differs from the machine tool control device 1 according to the first embodiment in that it further includes a correction value calculation unit 16 and an actual chip length acquisition unit 17, and in that, unlike the chip length calculation unit 13 of the first embodiment, the chip length calculation unit 13A also corrects the chip length, but the other configurations are the same as those of the first embodiment.

[0037] The actual chip length acquisition unit 17 acquires the actual chip length obtained by actually measuring the chip length of the chip obtained by actually performing the swing cutting process. The acquired actual chip length is output to the correction value calculation unit 16, which will be described later.

[0038] The correction value calculation unit 16 calculates a correction value used to correct the chip length. Specifically, the correction value calculation unit 16 calculates the correction value based on the theoretical chip length calculated by the chip length calculation unit 13A and the measured actual chip length acquired by the actual chip length acquisition unit 17. For example, the correction value calculation unit 16 calculates a correction coefficient or correction amount based on the deviation factor or difference between the theoretical chip length and the actual chip length obtained by actually performing oscillation cutting under the machining conditions and oscillation conditions used for the calculation. The calculated correction value is output to the chip length calculation unit 13A, which will be described later.

[0039] Furthermore, it is preferable that the correction value calculation unit 16 calculates the correction value for each machining condition. Specifically, it is preferable that the correction value calculation unit 16 calculates the correction value for each machining condition including, for example, at least one of the material of the cutting tool tip, the shape of the cutting tool tip, the material of the workpiece, the cutting speed, the cutting depth, and the cutting angle.

[0040] The chip length calculation unit 13A calculates the chip length based on the machining conditions and oscillation conditions acquired by the condition acquisition unit 12, using the same calculation method as the chip length calculation unit 13 of the first embodiment. Moreover, unlike the chip length calculation unit 13 of the first embodiment, the chip length calculation unit 13A corrects the calculated theoretical chip length using a correction value calculated by the correction value calculation unit 16.

[0041] Next, a first example of a chip length correction method by the chip length calculation unit 13A will be described in detail with reference to FIGS. 7 to 10. FIGS. 7 and 8 are diagrams showing a first example of a chip length correction table. FIG. 9 is a diagram showing a chip length confirmation screen on which the calculated chip length is displayed. FIG. 10 is a diagram showing a chip length confirmation screen on which the chip length corrected based on the chip length correction coefficient is displayed.

[0042] First, as in the first embodiment described above, the operator inputs a workpiece radial coordinate value X, which is information related to the machining diameter, as a machining condition, and also inputs an oscillation frequency magnification I and an oscillation amplitude magnification K, which are oscillation conditions. Then, as shown in Figure 9, the theoretical chip length automatically calculated by the chip length calculation unit 13A is displayed as the chip length on the chip length confirmation screen. In addition, the operator operates the machine tool control device 1A before and after the above input operation to actually perform oscillation cutting under the machining conditions and oscillation conditions used to calculate the theoretical chip length, and measures the length of the resulting chip.

[0043] Next, in order to correct the calculated theoretical chip length, the operator operates the input means of the input unit 11 to open a chip length correction table as shown in Fig. 7. Then, as shown in Fig. 7, the calculated theoretical chip length is automatically displayed in the chip length correction table in addition to the coordinate value X in the workpiece radial direction, the oscillation frequency magnification I, and the oscillation amplitude magnification K input on the chip length confirmation screen.

[0044] Therefore, the operator operates the input means of the input unit 11 to input the actual chip length obtained by actual measurement. Then, the correction value calculation unit 16 automatically calculates a correction coefficient based on, for example, the deviation magnification between the theoretical chip length and the actual chip length, and the calculated correction coefficient is automatically displayed in the chip length correction table. Furthermore, as shown in Fig. 10, the chip length displayed on the chip length confirmation screen is changed to the chip length value corrected using the correction coefficient.

[0045] 7 and 8, when there are multiple combinations of input machining conditions and oscillation conditions, and multiple combinations of theoretical chip lengths and actual chip lengths exist for each combination of conditions, it is preferable that the correction value calculation unit 16 automatically calculates the correction coefficient based on the arithmetic mean of the deviation magnifications between the theoretical chip length and the actual chip length calculated for each combination. When deriving the correction coefficient from the deviation magnification, other data analysis methods such as the geometric mean, harmonic mean, median, and mode may be used.

[0046] Next, a second example of a method for correcting chip length by the chip length calculation unit 13A will be described in detail with reference to FIGS. 11 to 14. FIGS. 11 and 12 are diagrams showing a second example of a chip length correction table. FIG. 13 is a diagram showing a chip length confirmation screen on which the calculated chip length is displayed. FIG. 14 is a diagram showing a chip length confirmation screen on which the corrected chip length for each type of workpiece is displayed.

[0047] First, the operator inputs the workpiece radial coordinate value X, which is information related to the machining diameter, and the type of workpiece (material), as machining conditions, and also inputs the oscillation frequency magnification I and oscillation amplitude magnification K, which are oscillation conditions. Then, as shown in Figure 13, the theoretical chip length automatically calculated by the chip length calculation unit 13A corresponding to the selected workpiece type is displayed as the chip length on the chip length confirmation screen. In addition, before and after the above input operation, the operator operates the control device 1A of the machine tool to actually perform oscillation cutting under the machining conditions and oscillation conditions used to calculate the theoretical chip length, and measures the length of the resulting chip.

[0048] Next, in order to correct the calculated theoretical chip length, the operator operates the input means of the input unit 11 to open a chip length correction table as shown in Fig. 11. Then, as shown in Fig. 11, the chip length correction table automatically displays the calculated theoretical chip length in addition to the coordinate value X in the workpiece radial direction, the type of workpiece, the oscillation frequency magnification I, and the oscillation amplitude magnification K input on the chip length confirmation screen.

[0049] Therefore, the operator operates the input means of the input unit 11 to input the actual chip length obtained by actual measurement. Then, the correction value calculation unit 16 automatically calculates a correction coefficient based on, for example, the deviation magnification between the theoretical chip length and the actual chip length, and the calculated correction coefficient is automatically displayed in the chip length correction table. Furthermore, as shown in Fig. 14, the chip length displayed on the chip length confirmation screen is changed to the chip length value corrected using the correction coefficient.

[0050] 11 and 12, the correction coefficient is calculated for each type of workpiece. In this second example, an example was given in which the correction coefficient was calculated for each type of workpiece, but correction values ​​such as the correction coefficient may be calculated for each machining condition including not only the type of workpiece but also at least one of the material of the cutting tool cutting edge, the shape of the cutting tool cutting edge, the cutting speed, the depth of cut, and the depth of cut angle. Also, as in the first example, when there are multiple combinations of input machining conditions and oscillation conditions and multiple combinations of theoretical chip length and actual chip length depending on each combination of conditions, it is preferable that the correction value calculation unit 16 automatically calculates the correction coefficient based on the average value of the deviation magnification between the theoretical chip length and the actual chip length calculated for each combination.

[0051] The machine tool control device 1A according to the second embodiment has the following advantages.

[0052] The machine tool control device 1A according to the second embodiment is further provided with a correction value calculation unit 16 that calculates a correction value used to correct the chip length, and is configured to correct the calculated chip length using the correction value calculated by the correction value calculation unit 16. More specifically, it is further provided with an actual chip length acquisition unit 17 that acquires the actual chip length obtained by actually performing machining, and is configured to calculate the correction value based on the calculated theoretical chip length and the actual chip length. This makes it possible to calculate a more accurate chip length.

[0053] In the machine tool control device 1A according to the second embodiment, the correction value calculation unit 16 is configured to calculate a correction value for each machining condition. More specifically, the correction value calculation unit 16 is configured to calculate a correction value for each machining condition including at least one of the material of the cutting tool tip, the shape of the cutting tool tip, the material of the workpiece, the cutting speed, the cutting depth, and the cutting angle. This allows for even more accurate chip length calculation.

[0054] [Third embodiment] Figure 15 is a functional block diagram of a machine tool control device 1B according to a third embodiment. As shown in Figure 15, the machine tool control device 1B according to the third embodiment differs from the machine tool control device 1 according to the first embodiment in that it further includes a correction value calculation unit 16A and an actual swing amplitude acquisition unit 18, and in that, unlike the chip length calculation unit 13 of the first embodiment, a chip length calculation unit 13B also corrects the chip length, but the other configurations are the same as those of the first embodiment.

[0055] The actual oscillation amplitude acquisition unit 18 acquires, as the actual oscillation amplitude, the oscillation amplitude of the cutting path measured by actually performing oscillation cutting under the machining conditions and oscillation conditions used to calculate the theoretical chip length. The actual measurement value of the cutting path can be acquired by a position detector such as an encoder that is normally provided in a servo motor. The acquired actual oscillation amplitude is output to the correction value calculation unit 16A, which will be described later.

[0056] The correction value calculation unit 16A calculates a correction value used to correct the chip length. Specifically, the correction value calculation unit 16A calculates the correction value based on the attenuation rate of the actual oscillation amplitude acquired by the actual oscillation amplitude acquisition unit 18 relative to the oscillation amplitude acquired by the condition acquisition unit 12, i.e., the oscillation amplitude command value. For example, the attenuation rate itself is used as the correction value. The calculated correction value is output to the chip length calculation unit 13B, which will be described later.

[0057] Furthermore, similar to the correction value calculation unit 16 of the second embodiment, it is preferable that the correction value calculation unit 16A calculates a correction value for each machining condition, specifically for each machining condition including at least one of the material of the cutting tool tip, the shape of the cutting tool tip, the material of the workpiece, the cutting speed, the cutting depth, and the cutting angle.

[0058] The chip length calculation unit 13B calculates a theoretical chip length based on the machining conditions and oscillation conditions acquired by the condition acquisition unit 12, using the same calculation method as the chip length calculation unit 13 of the first embodiment. Furthermore, when calculating the chip length using the above-mentioned formula (1), the chip length calculation unit 13B calculates the chip length by substituting a value obtained by multiplying the oscillation amplitude magnification K by a damping rate as a correction value into formula (1) instead of the oscillation amplitude magnification K. This makes it possible to calculate a chip length corrected based on the damping rate.

[0059] Next, the method of correcting the chip length by the chip length calculation unit 13B will be described in detail with reference to Figs. 16 to 18. Fig. 16 is a diagram showing the attenuation rate of the actual measurement value relative to the command value of the oscillation amplitude. Fig. 17 is a diagram showing a chip length confirmation screen on which the attenuation rate of the oscillation amplitude is input. Fig. 18 is a diagram showing a chip length confirmation screen on which the chip length corrected based on the attenuation rate of the oscillation amplitude is displayed.

[0060] First, as in the first embodiment described above, the operator inputs a workpiece radial coordinate value X, which is information related to the machining diameter, as a machining condition, and also inputs an oscillation frequency magnification I and an oscillation amplitude magnification K, which are oscillation conditions. Then, as shown in Figure 17, the theoretical chip length automatically calculated by the chip length calculation unit 13B is displayed as the chip length on the chip length confirmation screen. In addition, the operator operates the machine tool control device 1A before and after the above input operation to actually perform oscillation cutting under the machining conditions and oscillation conditions used to calculate the theoretical chip length, and obtains actual measurement values ​​of the cutting path.

[0061] Next, the correction value calculation unit 16A calculates the attenuation rate of the actual measurement value for the oscillation amplitude relative to the command value by comparing the command value and the actual measurement value of the cutting path, and sets the calculated attenuation rate itself as the correction value, as shown in Fig. 16. Then, the chip length calculation unit 13B calculates the chip length corrected based on the attenuation rate, and as shown in Fig. 18, the attenuation rate of the amplitude is displayed on the chip length confirmation screen, and the display of the chip length is changed to the chip length value corrected based on the attenuation rate.

[0062] The machine tool control device 1B according to the third embodiment provides the following effects.

[0063] The machine tool control device 1B according to the third embodiment is further provided with an actual oscillation amplitude acquisition unit 18 that acquires an actual oscillation amplitude obtained by actually performing oscillation cutting, and the correction value calculation unit 16A is configured to calculate a correction value based on the attenuation rate of the actual oscillation amplitude acquired by the actual oscillation amplitude acquisition unit 18 relative to the oscillation amplitude acquired by the condition acquisition unit 12. This makes it possible to calculate a more accurate chip length.

[0064] The present disclosure is not limited to the above-described embodiments, and includes modifications and improvements within the scope of achieving the object of the present disclosure.

[0065] For example, in the second and third embodiments, the correction values ​​are automatically calculated by the correction value calculation units 16 and 16A, but the present invention is not limited to this. The correction values ​​may be calculated by an external computer or otherwise acquired, and then manually input and set by an operator.

[0066] For example, in the third embodiment, if the attenuation rate of the actual oscillation amplitude is known from the results of the frequency response of the machine, the correction value may be calculated based on that attenuation rate.

[0067] 1, 1A, 1B Machine tool control device 11 Input section 12 Condition acquisition section 13, 13A, 13B Chip length calculation section 14 Chip length output section 15 Chip length display section 16, 16A Correction value calculation section 17 Actual chip length acquisition section 18 Actual oscillation amplitude acquisition section

Claims

1. A control device for a machine tool that performs machining while relatively swinging a cutting tool and a workpiece, A condition acquisition unit that acquires processing conditions and swing conditions; a chip length calculation unit that calculates a chip length based on the machining conditions and the swing conditions acquired by the condition acquisition unit; a chip length output unit that outputs the chip length calculated by the chip length calculation unit.

2. The control device for a machine tool according to claim 1 , further comprising a chip length display unit that displays the chip length output by the chip length output unit.

3. The condition acquisition unit, As the machining conditions, information regarding the machining diameter is obtained, The control device for a machine tool according to claim 1 or 2, wherein the oscillation conditions include information regarding the relative number of oscillations per rotation between the cutting tool and the workpiece, and information regarding the oscillation amplitude for the relative feed amount per rotation between the cutting tool and the workpiece.

4. A correction value calculation unit is further provided for calculating a correction value used for correcting the chip length, 3. The control device for a machine tool according to claim 1 or 2, wherein the chip length calculation unit corrects the chip length calculated based on the machining conditions and the swing conditions acquired by the condition acquisition unit, using the correction value calculated by the correction value calculation unit.

5. An actual chip length acquisition unit that acquires an actual chip length obtained by actually executing the machining, 5. The control device for a machine tool according to claim 4, wherein the correction value calculation unit calculates the correction value based on the chip length calculated by the chip length calculation unit and the actual chip length acquired by the actual chip length acquisition unit.

6. The control device for a machine tool according to claim 4 , wherein the correction value calculation section calculates the correction value based on a damping rate of an actual swing amplitude relative to a swing amplitude.

7. An actual swing amplitude acquisition unit that acquires an actual swing amplitude obtained by actually executing the machining, The condition acquisition unit acquires a swing amplitude, The control device for a machine tool according to claim 6, wherein a attenuation rate of the actual swing amplitude relative to the swing amplitude is calculated based on the swing amplitude acquired by the condition acquisition unit and the actual swing amplitude acquired by the actual swing amplitude acquisition unit.

8. The control device for a machine tool according to claim 4 , wherein the compensation value calculation unit calculates the compensation value for each of the machining conditions.

9. 9. The control device for a machine tool according to claim 8, wherein the correction value calculation unit calculates the correction value for each of the machining conditions including at least one of a material of the cutting edge of the cutting tool, a shape of the cutting edge of the cutting tool, a material of the workpiece, a cutting speed, a cutting depth, and a cutting angle.