Control device for machine tool

Abstract

Provided is a technique whereby surface roughness can be calculated and machining conditions and swing conditions can be easily set while the calculated surface roughness is confirmed. A control device (1) for a machine tool that performs machining while swinging a cutting tool and a workpiece relative to each other is provided with: a condition acquisition unit (12) that acquires a machining condition and a swinging condition; a surface roughness calculation unit (13) that calculates a surface roughness on the basis of the machining condition and the oscillation condition acquired by the condition acquisition unit (12); and a surface roughness output unit (14) that outputs the surface roughness calculated by the surface roughness calculation unit (13).

Description

Technical Field

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

[0002] Conventionally, in order to prevent the chips continuously generated during cutting from being entangled in the workpiece or cutting tool, thereby causing machining defects, mechanical failures, etc., there is known a swing cutting method in which the cutting tool and the workpiece are swung relative to each other while cutting the workpiece. In this swing cutting, the tool path, which is the trajectory of the cutting tool, is set to overlap a portion of the previous tool path by adjusting the swing frequency and the swing amplitude. Thus, the chips are broken by generating a swing called a blank cut in which the cutting tool tip is separated from the surface of the workpiece.

[0003] However, the surface roughness of the machined workpiece when the oscillating cutting is applied is often worse than when the oscillating cutting is not applied. This is because the path of the cutting tool when the oscillating cutting is applied becomes the trajectory of the oscillating motion according to the specified oscillating condition. Therefore, a technology for calculating the surface roughness based on, for example, the shape of the cutting tool tip, the rotation speed of the spindle, and the feed speed has been proposed (for example, refer to Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-114614 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, the calculation of surface roughness depends on the processing conditions and the swing conditions, so it is difficult to set the processing conditions and the swing conditions while considering the surface roughness. Therefore, a technology that can calculate the surface roughness and easily set the processing conditions and the swing conditions while confirming the calculated surface roughness is desired.

[0009] The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide a technology capable of calculating surface roughness and easily setting machining conditions and swing conditions while confirming the calculated surface roughness.

[0010] Means for solving problems

[0011] The present invention discloses a control device for a machine tool that performs processing while causing a cutting tool and a workpiece to swing relative to each other, the control device comprising: a condition acquisition unit that acquires processing conditions and swing conditions; a surface roughness calculation unit that calculates surface roughness based on the processing conditions and swing conditions acquired by the condition acquisition unit; and a surface roughness output unit that outputs the surface roughness calculated by the surface roughness calculation unit.

[0012] Effects of the Invention

[0013] According to the present disclosure, it is possible to provide a technology that can calculate surface roughness and easily set machining conditions and swing conditions while confirming the calculated surface roughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram for explaining swing cutting.

[0015] Figure 2 This is a functional block diagram of the control device for the machine tool according to the first embodiment.

[0016] Figure 3 This is a diagram showing a surface roughness confirmation screen in which machining conditions and swing conditions are input.

[0017] Figure 4 It is a diagram showing the cutting path.

[0018] Figure 5 It is a figure which shows the surface roughness confirmation screen which displays the calculated surface roughness.

[0019] Figure 6 It is a diagram showing the phase of the obtained roughness curve.

[0020] Figure 7 It is a graph showing a roughness curve.

[0021] Figure 8 This is a functional block diagram of a control device for a machine tool according to a second embodiment.

[0022] Fig. 9 It is a diagram showing a first example of the surface roughness correction table.

[0023] Fig.10 It is a diagram showing a first example of the surface roughness correction table.

[0024] Fig.11 It is a figure which shows the surface roughness confirmation screen which displays the calculated surface roughness.

[0025] Fig.12 The figure shows the surface roughness confirmation screen which displays the surface roughness corrected based on the correction coefficient of the surface roughness.

[0026] Fig.13 It is a diagram showing a second example of the surface roughness correction table.

[0027] Fig.14 It is a diagram showing a second example of the surface roughness correction table.

[0028] Fig.15 It is a figure which shows the surface roughness confirmation screen which displays the calculated surface roughness.

[0029] Fig.16 The figure shows a surface roughness confirmation screen showing the surface roughness corrected for each type of workpiece.

[0030] Fig.17 This is a functional block diagram of a control device for a machine tool according to a third embodiment.

[0031] Fig.18 This is a graph showing the attenuation rate of the actual measured value of the swing amplitude with respect to the command value of the swing amplitude.

[0032] Fig.19 It is a figure which shows the surface roughness confirmation screen which inputs the attenuation rate of the vibration amplitude.

[0033] Fig. 20 The figure shows a surface roughness confirmation screen showing the surface roughness corrected based on the attenuation rate of the vibration amplitude. DETAILED DESCRIPTION

[0034] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description of the second embodiment and thereafter, the same reference numerals are given to the same configurations as those of the first embodiment, and the description thereof will be omitted as appropriate.

[0035] [First embodiment]

[0036] The control device for a machine tool according to the first embodiment executes swing cutting for cutting a workpiece while swinging a cutting tool and the workpiece relative to each other. Figure 1 This is a diagram for explaining swing cutting. Figure 1In the example of swing cutting shown, at least one spindle S and at least one feed axis (not shown) are operated to rotate the cutting tool T and the workpiece W relative to each other, and the cutting tool T and the workpiece W are swung relative to each other in the feed direction while cutting. The at least one spindle S rotates the cutting tool T and the workpiece W relative to each other, and the at least one feed axis moves the cutting tool T relative to the workpiece W. At this time, the tool path as the trajectory of the cutting tool T is set so that the current path and the previous path partially overlap. That is, the current path partially includes the part that was processed in the previous path, so that the cutting tool T is separated from the surface of the workpiece W, which is called an empty swing, and the chips are broken.

[0037] In addition, in the swing cutting performed in this embodiment, the shape of the workpiece is not limited. That is, even if the workpiece has a tapered portion or an arc portion on the processing surface and multiple feed axes (Z axis and X axis) are required, even if the workpiece is cylindrical or cylindrical and a specific feed axis (Z axis) is sufficient, it can also be applied.

[0038] Figure 2 1 is a functional block diagram of the control device 1 of the machine tool according to the first embodiment. Figure 2 As shown, the control device 1 of the machine tool of the first embodiment includes an input unit 11, a condition acquisition unit 12, a surface roughness calculation unit 13, a surface roughness output unit 14, and a surface roughness display unit 15. The control device 1 of the machine tool is configured using, for example, a computer including a memory such as a ROM (read only memory) and a RAM (random access memory) connected to each other via a bus, a CPU (control processing unit), and a communication control unit. The functions and actions of the above-mentioned functional units are realized by the cooperation of the CPU, the memory, and the control program stored in the memory mounted on the above-mentioned computer.

[0039] The control device 1 of the machine tool may be composed of a CNC (Computer Numerical Controller), and may also be connected to a host computer (not shown) such as a CNC or a PLC (Programmable Logic Controller). In addition to the machining program, machining conditions such as rotation speed and feed speed, and swing conditions such as swing amplitude and swing frequency are input from the host computer to the control device 1 of the machine tool.

[0040] The input unit 11 inputs information related to machining conditions and swing conditions according to an operator's input operation on an input unit (not shown) such as a keyboard or a touch panel. The information related to machining conditions and swing conditions input by the input unit 11 is output to a condition acquisition unit 12 described later.

[0041] The condition acquisition unit 12 acquires the machining conditions and the swing conditions inputted through the input unit 11. The condition acquisition unit 12 outputs the acquired machining conditions and the swing conditions to the surface roughness calculation unit 13 described later.

[0042] Here, the processing conditions include at least information on the feed amount per one rotation of the cutting tool and the workpiece relative to each other and information on the shape of the cutting edge of the cutting tool, and also include information on, for example, the spindle speed S (1 / min), the feed speed of the cutting tool (mm / min), the workpiece diameter (mm), the back angle (°) of the cutting tool, etc. In addition, as information on the feed amount per one rotation of the cutting tool and the workpiece relative to each other, the feed amount per one rotation F (mm / rev) can be cited, and as information on the shape of the cutting edge of the cutting tool, the R (mm) of the cutting edge can be cited.

[0043] In addition, as the swing condition, information related to the number of swings per one rotation of the cutting tool and the workpiece relative to each other and information on the swing amplitude relative to the feed amount per one rotation of the cutting tool and the workpiece relative to each other are included. As the information related to the number of swings per one rotation of the cutting tool and the workpiece relative to each other, a swing frequency magnification I (times) indicating the swing frequency per one rotation of the spindle can be cited. In addition, as the information on the swing amplitude relative to the feed amount per one rotation of the cutting tool and the workpiece relative to each other, a swing amplitude magnification K (times) indicating the size of the swing amplitude relative to the size of the feed amount per one rotation of the spindle can be cited. The swing frequency magnification I (times) can be directly specified, or it can be calculated based on the swing frequency (Hz) and the spindle rotation speed S (1 / min) after specifying the swing frequency (Hz). In addition, the swing amplitude magnification K (times) can also be directly specified, or it can be calculated based on the swing amplitude (mm), the feed speed (mm / min) and the spindle rotation speed S (1 / min) after specifying the swing amplitude (mm).

[0044] The surface roughness calculation unit 13 calculates the surface roughness based on the processing conditions and the swing conditions acquired by the condition acquisition unit 12. The surface roughness calculated by the surface roughness calculation unit 13 includes, for example, at least one of the arithmetic mean roughness, the maximum height of the maximum distance between the peak and the valley, the maximum peak height of the maximum height from the average line of the surface, the maximum valley depth of the absolute value of the minimum height from the average line of the surface, the average height of the height of the profile curve element with adjacent peaks and valleys as a group, the maximum cross-sectional height of the sum of the maximum height of the peak of the profile curve element and the maximum depth of the valley, and the load length ratio of the load length of the profile curve element at a predetermined cutting level (height % or μm) to the evaluation reference length. The specific calculation method of these surface roughnesses will be described in detail later.

[0045] The surface roughness output unit 14 outputs the surface roughness calculated by the surface roughness calculation unit 13 to the outside. In the present embodiment, the surface roughness output unit 14 outputs the calculated surface roughness to the surface roughness display unit 15 described later.

[0046] The surface roughness display unit 15 displays the surface roughness output by the surface roughness output unit 14. Specifically, the surface roughness display unit 15 displays the surface roughness calculated by the surface roughness calculation unit 13 on a surface roughness confirmation screen described in detail later.

[0047] Next, refer to Figure 3 to Figure 5 The method of calculating the surface roughness by the surface roughness calculation unit 13 will be described in detail. Figure 3 This is a diagram showing a surface roughness confirmation screen in which machining conditions and swing conditions are input. Figure 4 It is a diagram showing the cutting path. Figure 5 It is a figure which shows the surface roughness confirmation screen which displays the calculated surface roughness.

[0048] like Figure 3 As shown, first, the operator uses the surface roughness confirmation screen displayed by the surface roughness display unit 15 to input the processing conditions and the swing conditions by operating the input unit 11. Figure 3 As shown in the example, as processing conditions, the operator inputs information related to the feed amount per relative rotation of the cutting tool and the workpiece, i.e., the feed amount per rotation F (mm / rev) and information related to the shape of the cutting edge of the cutting tool, i.e., the cutting edge R (mm), and inputs the swing frequency multiplier I and the swing amplitude multiplier K as swing conditions.

[0049] Then, the condition acquisition unit 12 acquires the input machining conditions and swing conditions, and the surface roughness calculation unit 13 automatically calculates the surface roughness based on the acquired machining conditions and swing conditions. Specifically, the surface roughness calculation unit 13 uses the following formula (1) to calculate the coordinate value Y (mm) of the feed direction of the cutting path, and searches for the position where the distance between the cutting paths is the largest.

[0050]

[0051] In formula (1), Y represents the coordinate value of the feed direction (mm), f represents the feed amount per spindle rotation (mm / rev), S represents the spindle speed (1 / min), I represents the swing frequency multiplier (times), K represents the swing amplitude multiplier (times), and t represents time (sec).

[0052] exist Figure 4 The position where the distance between the cutting paths is the largest is represented in . In this embodiment, the coordinate values ​​Y of the position where the distance between the cutting paths is the largest are obtained by the above-mentioned formula (1), and the distance between the obtained coordinate values ​​is taken as the maximum distance between the cutting paths. And, for example, when the maximum value of the distance between the peak and the valley, i.e., the maximum height Rz, is calculated as the surface roughness, the maximum height Rz can be calculated by substituting the R (mm) of the tool tip and the maximum distance between the cutting paths obtained as described above into the following formula (2).

[0053] Maximum height Rz (μm) = (maximum distance between cutting paths) 2 / 8R×1000 formula (2)

[0054] Here, in the prior art, the surface roughness after the oscillation cutting is calculated based on the machining conditions such as the shape of the cutting tool tip, the rotation speed of the spindle, and the feed speed. In contrast, in the surface roughness calculation unit 13 of the present embodiment, according to the above-mentioned surface roughness calculation method, the oscillation frequency magnification I and the oscillation amplitude magnification K as the oscillation conditions are also included in the calculation conditions to calculate the surface roughness. Therefore, according to the surface roughness calculation unit 13 of the present embodiment, a more accurate surface roughness can be calculated compared with the past.

[0055] In addition, the surface roughness calculated by the surface roughness calculation unit 13 as described above is as follows: Figure 5 The surface roughness confirmation screen is automatically displayed as shown. Figure 5 In the display, the maximum height is displayed as the surface roughness. Thus, the operator can set the machining conditions and the swing conditions while confirming the surface roughness calculated more accurately than before, and the setting of the machining conditions and the swing conditions becomes easy.

[0056] In addition, refer to Figure 6 and Figure 7 For example, a case where the arithmetic mean roughness Ra is calculated as the surface roughness will be described in detail. Figure 6 It is a diagram showing the phase of the obtained roughness curve. Figure 7 It is a graph showing a roughness curve.

[0057] Figure 6 Yes Figure 4 The cutting path shown in the figure is rotated 90 degrees, which is an example of using the phase of the position where the distance between the above-mentioned cutting paths is the largest as the phase of the roughness curve of the workpiece processing surface. By configuring the arc of the radius R of the tool tip at the coordinate value of the cutting path at this phase, it is possible to obtain Figure 7 In this way, the roughness curve of the workpiece processing surface taking into account the cutting tool tip R can be obtained by Figure 7 The Z value in the roughness curve is substituted into the following formula (3) to calculate the arithmetic mean roughness Ra.

[0058]

[0059] According to the control device 1 for a machine tool according to the first embodiment, the following effects are achieved.

[0060] In the control device 1 of the machine tool of the present embodiment, a condition acquisition unit 12 for acquiring machining conditions and swing conditions, a surface roughness calculation unit 13 for calculating surface roughness based on the machining conditions and swing conditions, and a surface roughness output unit 14 for outputting the calculated surface roughness are provided. Thus, the surface roughness depends on the machining conditions and swing conditions, and it was difficult to set the machining conditions and swing conditions while considering the surface roughness in the past. According to the present embodiment, the surface roughness can be calculated based on the machining conditions and swing conditions, and the machining conditions and swing conditions can be easily set while confirming the surface roughness calculated and output to the outside.

[0061] In addition, the control device 1 of the machine tool of the present embodiment is further provided with a surface roughness display unit 15 which displays the surface roughness output by the surface roughness output unit 14. Thus, the operator can more easily set the machining conditions and the swing conditions while checking the surface roughness displayed on the display screen of the surface roughness display unit 15 or the like.

[0062] In addition, in the control device 1 of the machine tool of the present embodiment, it is configured to obtain information about the feed amount per one rotation of the cutting tool and the workpiece relative to each other and information about the shape of the cutting tool tip as machining conditions, and to obtain information about the number of swings per one rotation of the cutting tool and the workpiece relative to each other and information about the swing amplitude relative to the feed amount per one rotation of the cutting tool and the workpiece relative to each other as swing conditions, and calculate the surface roughness based on these machining conditions and swing conditions. Thus, although the surface roughness depends on the swing condition, the swing condition has not been considered in the past, but according to the present embodiment, the swing condition can be included in the calculation condition to calculate the surface roughness, and a more accurate surface roughness can be calculated.

[0063] [Second embodiment]

[0064] Figure 8 1A is a functional block diagram of a control device 1A for a machine tool according to a second embodiment. Figure 8 As shown, the control device 1A of the machine tool of the second embodiment is different from the control device 1 of the machine tool of the first embodiment in that it also includes a correction value calculation unit 16 and an actual surface roughness acquisition unit 17, and unlike the surface roughness calculation unit 13 of the first embodiment, the surface roughness calculation unit 13A also performs surface roughness correction. The other structures are the same as those of the first embodiment.

[0065] The actual surface roughness acquisition unit 17 acquires the actual surface roughness obtained by actually measuring the surface roughness of the workpiece machined surface obtained by actually performing the oscillating cutting process, and outputs the acquired actual surface roughness to the correction value calculation unit 16 described later.

[0066] The correction value calculation unit 16 calculates a correction value for correcting the surface roughness. Specifically, the correction value calculation unit 16 calculates the correction value based on the theoretical surface roughness calculated by the surface roughness calculation unit 13A and the actual surface roughness measured by the actual surface roughness acquisition unit 17. For example, the correction value calculation unit 16 calculates a correction coefficient or a correction amount based on the deviation ratio or difference between the actual surface roughness obtained by actually performing the swing cutting process under the machining conditions used in the calculation and the swing conditions and the theoretical surface roughness. The calculated correction value is output to the surface roughness calculation unit 13A described later.

[0067] In addition, the correction value calculation unit 16 preferably calculates the correction value for each machining condition. Specifically, the correction value calculation unit 16 preferably calculates the correction value for each machining condition including at least one of the material of the cutting edge of the cutting tool, the shape of the cutting edge of the cutting tool, the material of the workpiece, the cutting speed, the cutting thickness, and the cutting angle.

[0068] The surface roughness calculation unit 13A calculates the surface roughness based on the machining conditions and the swing conditions acquired by the condition acquisition unit 12 by the same calculation method as the surface roughness calculation unit 13 of the first embodiment. In addition, the surface roughness calculation unit A, unlike the surface roughness calculation unit 13 of the first embodiment, uses the correction value calculated by the correction value calculation unit 16 to correct the calculated theoretical surface roughness.

[0069] Next, refer to Figures 9 to 12 A first example of a method of correcting the surface roughness by the surface roughness calculation unit 13A will be described in detail. Fig. 9 and Fig.10 It is a diagram showing a first example of the surface roughness correction table. Fig.11 It is a figure which shows the surface roughness confirmation screen which displays the calculated surface roughness.

[0070] Fig.10 The figure shows the surface roughness confirmation screen which displays the surface roughness corrected based on the correction coefficient of the surface roughness.

[0071] First, as machining conditions, the operator inputs information related to the feed amount per rotation of the cutting tool and the workpiece, i.e., the feed amount per rotation F (mm / rev), information related to the shape of the cutting edge of the cutting tool, i.e., the cutting edge R (mm), and the spindle speed S (1 / min), and inputs the swing frequency magnification I and the swing amplitude magnification K as swing conditions. Then, as Fig.11 As shown in FIG. 1 , the theoretical surface roughness automatically calculated by the surface roughness calculation unit 13A is displayed as the surface roughness on the surface roughness confirmation screen. Fig.11 In the figure, the maximum height Rz is shown as the surface roughness ( Fig.12 Also, the operator operates the control device 1A of the machine tool before and after the above input operation to actually measure the surface roughness of the workpiece machined surface obtained by actually performing the oscillating cutting process under the machining conditions and oscillating conditions used in the calculation of the theoretical surface roughness.

[0072] Next, the operator operates the input unit of the input unit 11 to open the input unit 11 in order to correct the calculated theoretical surface roughness. Fig. 9 The surface roughness correction table is shown in FIG. Fig. 9 As shown in the figure, in addition to the feed rate F per revolution, tool tip R, spindle speed S, swing frequency magnification I, and swing amplitude magnification K entered in the surface roughness confirmation screen, the calculated theoretical surface roughness is also automatically displayed in the surface roughness correction table. Fig. 9 In the figure, the theoretical maximum height Rz ( Fig.10 Same).

[0073] Therefore, the operator operates the input unit of the input unit 11 to input the actual surface roughness obtained by actual measurement. Fig. 9 In the figure, the actual maximum height Rz is shown as the actual surface roughness ( Fig.10 Thus, the correction value calculation unit 16 automatically calculates the correction coefficient based on, for example, the deviation ratio between the theoretical surface roughness and the actual surface roughness, and automatically displays the calculated correction coefficient in the surface roughness correction table. Fig.12 As shown, the display of the surface roughness on the surface roughness confirmation screen is changed to the value of the surface roughness corrected using the correction coefficient.

[0074] In addition, if Fig. 9 as well as Fig.10 As shown in FIG. 1 , when there are multiple combinations of input machining conditions and oscillation conditions, and there are multiple combinations of theoretical surface roughness and actual surface roughness according to the combinations of the conditions, it is preferred that the correction value calculation unit 16 automatically calculates the correction coefficient based on the arithmetic mean of the deviation magnifications of the theoretical surface roughness and the actual surface roughness calculated in each combination. When deriving the correction coefficient based on the deviation magnification, other data analysis methods such as geometric mean, harmonic mean, median value, and mode value may also be used.

[0075] Next, refer to Figure 13 to Figure 16 A second example of the method of correcting the surface roughness by the surface roughness calculation unit 13A will be described in detail. Fig.13 and Fig.14 It is a diagram showing a second example of the surface roughness correction table. Fig.15 It is a figure which shows the surface roughness confirmation screen which displays the calculated surface roughness. Fig.16 The figure shows a surface roughness confirmation screen showing the surface roughness after correction for each type of workpiece.

[0076] First, as machining conditions, the operator inputs information related to the feed amount per rotation of the cutting tool and the workpiece, namely, the feed amount per rotation F (mm / rev), information related to the shape of the cutting edge of the cutting tool, namely, the R (mm) of the cutting edge, and the type (material) of the workpiece, and inputs the swing frequency magnification I and the swing amplitude magnification K as swing conditions. Fig.15 As shown in FIG. 1 , the theoretical surface roughness automatically calculated by the surface roughness calculation unit 13A is displayed as the surface roughness on the surface roughness confirmation screen in accordance with the type of the selected workpiece. Fig.15 In the figure, the maximum height Rz is shown as the surface roughness ( Fig.16Also, the operator operates the control device 1A of the machine tool before and after the above input operation to actually measure the surface roughness of the workpiece machined surface obtained by actually performing the oscillating cutting process under the machining conditions and oscillating conditions used in the calculation of the theoretical surface roughness.

[0077] Next, the operator operates the input unit of the input unit 11 to open the input unit 11 in order to correct the calculated theoretical surface roughness. Fig.13 The surface roughness correction table is shown in FIG. Fig.13 As shown in the figure, in the surface roughness correction table, in addition to the feed rate F per revolution, tool tip R, workpiece type, swing frequency magnification I, and swing amplitude magnification K entered in the surface roughness confirmation screen, the calculated theoretical surface roughness is also automatically displayed. Fig.13 In the figure, the theoretical maximum height Rz ( Fig.14 Same).

[0078] Therefore, the operator operates the input unit of the input unit 11 to input the actual surface roughness obtained by actual measurement. Fig.13 In the figure, the actual maximum height Rz is shown as the actual surface roughness ( Fig.14 Thus, the correction value calculation unit 16 automatically calculates the correction coefficient based on the deviation ratio between the theoretical surface roughness and the actual surface roughness, and automatically displays the calculated correction coefficient in the surface roughness correction table. Fig.16 As shown, the display of the surface roughness on the surface roughness confirmation screen is changed to the value of the surface roughness corrected using the correction coefficient.

[0079] In addition, if Fig.13 and Fig.14 As shown, a correction coefficient is calculated for each type of workpiece. In this second example, an example of calculating a correction coefficient for each type of workpiece is given, but correction values ​​such as correction coefficients can be calculated not only for the type of workpiece, but also for each processing condition including the material of the cutting tool tip, the shape of the cutting tool tip, the cutting speed, the cutting thickness, and the cutting angle. In addition, similar to the first example, when there are multiple combinations of input processing conditions and swing conditions, and there are multiple combinations of theoretical surface roughness and actual surface roughness according to the combination of each condition, it is preferred that the correction value calculation unit 16 automatically calculates the correction coefficient based on the arithmetic mean of the deviation magnification of the theoretical surface roughness and the actual surface roughness calculated in each combination. When deriving the correction coefficient based on the deviation magnification, other data analysis methods such as geometric mean, harmonic mean, central value, and most frequent value can also be used.

[0080] According to the control device 1A for a machine tool according to the second embodiment, the following effects are achieved.

[0081] In the control device 1A of the machine tool of the second embodiment, a correction value calculation unit 16 is further provided, and the correction value calculation unit 16 calculates a correction value for correcting the surface roughness, and the calculated surface roughness is corrected using the correction value calculated by the correction value calculation unit 16. More specifically, an actual surface roughness acquisition unit 17 is further provided, and the actual surface roughness acquisition unit 17 acquires the actual surface roughness obtained by actually performing the machining, and calculates the correction value based on the calculated theoretical surface roughness and the actual surface roughness. Thus, a more accurate surface roughness can be calculated.

[0082] In the control device 1A of the machine tool of the second embodiment, the correction value calculation unit 16 is configured to calculate the correction value for each machining condition. More specifically, the correction value calculation unit 16 is configured to calculate the correction value for each machining condition including at least one of the material of the cutting edge of the cutting tool, the shape of the cutting edge of the cutting tool, the material of the workpiece, the cutting speed, the cutting thickness, and the cutting angle. Thus, a more accurate surface roughness can be calculated.

[0083] [Third Embodiment]

[0084] Fig.17 1B is a functional block diagram of a machine tool control device according to the third embodiment. Fig.15 As shown, the control device 1B of the machine tool of the third embodiment is different from the control device 1 of the machine tool of the first embodiment in that it also has a correction value calculation unit 16A and an actual swing amplitude acquisition unit 18, and unlike the surface roughness calculation unit 13 of the first embodiment, the surface roughness calculation unit 13B also performs surface roughness correction. The other structures are the same as those of the first embodiment.

[0085] The actual swing amplitude acquisition unit 18 acquires the swing amplitude of the cutting path measured by actually performing the swing cutting process under the processing conditions and swing conditions for calculating the theoretical surface roughness as the actual swing amplitude. The measured value of the cutting path can be acquired by a position detector such as an encoder generally provided in the servo motor. The acquired actual swing amplitude is output to the correction value calculation unit 16A described later.

[0086] The correction value calculation unit 16A calculates a correction value for correcting the surface roughness. Specifically, the correction value calculation unit 16A calculates the correction value based on the attenuation rate of the actual swing amplitude obtained by the actual swing amplitude acquisition unit 18 relative to the swing amplitude obtained by the condition acquisition unit 12, that is, the swing amplitude command value. For example, the attenuation rate itself is used as the correction value. The calculated correction value is output to the surface roughness calculation unit 13B described later.

[0087] In addition, it is preferred that the correction value calculation unit 16A calculates the correction value for each processing condition, specifically, for each processing condition including at least any 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 thickness and the cutting angle, in the same manner as the correction value calculation unit 16 of the second embodiment.

[0088] The surface roughness calculation unit 13B calculates the theoretical surface roughness based on the processing conditions and the swing conditions acquired by the condition acquisition unit 12 by the same calculation method as the surface roughness calculation unit 13 of the first embodiment. In addition, when the surface roughness is calculated using the above-mentioned formula (1) by the same calculation method as the surface roughness calculation unit 13 of the first embodiment, the surface roughness is calculated by substituting the value obtained by multiplying the swing amplitude magnification K by the attenuation rate as a correction value into the formula (1) instead of the swing amplitude magnification K. In this way, the surface roughness corrected based on the attenuation rate can be calculated.

[0089] Next, refer to Figures 18 to 20 The surface roughness correction method performed by the surface roughness calculation unit 13B will be described in detail. Fig.18 This is a graph showing the attenuation rate of the actual measured value of the swing amplitude with respect to the command value of the swing amplitude. Fig.19 It is a figure which shows the surface roughness confirmation screen which inputs the attenuation rate of the vibration amplitude. Fig. 20 The figure shows a surface roughness confirmation screen showing the surface roughness corrected based on the attenuation rate of the vibration amplitude.

[0090] First, as machining conditions, the operator inputs information on the feed amount per rotation of the cutting tool and the workpiece, i.e., the feed amount per rotation F (mm / rev), and information on the shape of the cutting edge of the cutting tool, i.e., the cutting edge R (mm), and inputs the swing frequency magnification I and the swing amplitude magnification K as swing conditions. Fig.19 As shown in FIG. 1 , the theoretical surface roughness automatically calculated by the surface roughness calculation unit 13B is displayed as the surface roughness on the surface roughness confirmation screen. Fig.19 In the figure, the maximum height Rz is shown as the surface roughness ( Fig. 20 Also, the operator operates the control device 1A of the machine tool before and after the above-mentioned input operation, and actually performs the swing cutting process under the machining conditions and swing conditions for calculating the theoretical surface roughness, and obtains the actual measurement value of the cutting path.

[0091] Then, if Fig.18As shown in FIG. 1 , the correction value calculation unit 16A calculates the attenuation rate of the measured value of the swing amplitude relative to the command value of the swing amplitude by comparing the command value of the cutting path with the measured value, and uses the calculated attenuation rate itself as the correction value. Then, the surface roughness after correction based on the attenuation rate is calculated by the surface roughness calculation unit 13B, as shown in FIG. Fig. 20 As shown, the attenuation rate of the amplitude is displayed on the surface roughness confirmation screen, and the display of the surface roughness is changed to the value of the surface roughness corrected based on the attenuation rate.

[0092] According to the control device 1B for a machine tool according to the third embodiment, the following effects are achieved.

[0093] In the control device 1B of the machine tool of the third embodiment, an actual swing amplitude acquisition unit 18 is further provided, which acquires an actual swing amplitude obtained by actually performing the swing cutting process, and the correction value calculation unit 16A is configured to calculate the correction value based on the attenuation rate of the actual swing amplitude acquired by the actual swing amplitude acquisition unit 18 with respect to the swing amplitude acquired by the condition acquisition unit 12. In this way, a more accurate surface roughness can be calculated.

[0094] In addition, the present disclosure is not limited to the above-mentioned embodiment, and modifications and improvements within the scope that can achieve the purpose of the present disclosure are included in the present disclosure.

[0095] For example, in the second and third embodiments, the correction value is automatically calculated by the correction value calculation unit 16, 16A, but the present invention is not limited thereto and the operator may manually input and set the correction value obtained by calculation or the like by an external computer.

[0096] For example, in the third embodiment described above, if the attenuation rate of the actual vibration amplitude is known from the result of the frequency response of the machine, the correction value may be calculated based on the attenuation rate.

[0097] Description of Reference Numerals

[0098] 1. Control device of 1A and 1B machine tools

[0099] 11 Input section

[0100] 12 Condition Acquisition Department

[0101] 13, 13A, 13B Surface roughness calculation unit

[0102] 14Surface roughness output unit

[0103] 15Surface roughness display unit

[0104] 16.16A correction value calculation unit

[0105] 17 Actual surface roughness acquisition unit

[0106] 18: Actual swing amplitude acquisition unit.

Claims

1. A control device for a machine tool, wherein the machine tool performs machining while causing a cutting tool and a workpiece to swing relative to each other, characterized in that: The control device has: a condition acquisition unit that acquires processing conditions and swing conditions; a surface roughness calculation unit that calculates surface roughness based on the processing conditions and the swing conditions acquired by the condition acquisition unit; and A surface roughness output unit outputs the surface roughness calculated by the surface roughness calculation unit.

2. The control device for a machine tool according to claim 1, characterized in that: The control device further includes a surface roughness display unit that displays the surface roughness output by the surface roughness output unit.

3. The control device for a machine tool according to claim 1 or 2, characterized in that: The condition acquisition unit acquires information related to the feed amount per relative rotation of the cutting tool and the workpiece and information related to the shape of the cutting edge of the cutting tool as the processing conditions, and acquires information related to the number of swings per relative rotation of the cutting tool and the workpiece and information on the swing amplitude relative to the feed amount per relative rotation of the cutting tool and the workpiece as the swing conditions.

4. The control device for a machine tool according to any one of claims 1 to 3, characterized in that: The surface roughness includes at least one of arithmetic mean roughness, maximum height, maximum peak height, maximum valley depth, average height, maximum cross-sectional height, and load length ratio.

5. The control device for a machine tool according to any one of claims 1 to 4, characterized in that: The control device further includes a correction value calculation unit that calculates a correction value for correcting the surface roughness. The surface roughness calculation unit corrects the surface roughness calculated based on the machining condition and the swing condition acquired by the condition acquisition unit using the correction value calculated by the correction value calculation unit.

6. The control device for a machine tool according to claim 5, characterized in that: The control device further includes an actual surface roughness acquisition unit that acquires an actual surface roughness obtained by actually performing the processing. The correction value calculation unit calculates the correction value based on the surface roughness calculated by the surface roughness calculation unit and the actual surface roughness acquired by the actual surface roughness acquisition unit.

7. The control device for a machine tool according to claim 5, characterized in that: The correction value calculation unit calculates the correction value based on a decay rate of an actual swing amplitude with respect to a swing amplitude.

8. The control device for a machine tool according to claim 7, characterized in that: The control device further includes an actual swing amplitude acquisition unit that acquires an actual swing amplitude obtained by actually executing the machining. The condition acquisition unit acquires the swing amplitude, An attenuation rate of an actual swing amplitude with respect 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.

9. The control device for a machine tool according to any one of claims 5 to 8, characterized in that: The correction value calculation unit calculates the correction value for each of the machining conditions.

10. The control device for a machine tool according to claim 9, characterized in that: The correction value calculation unit calculates the correction value for each of the machining conditions including at least one of the material of the cutting edge of the cutting tool, the shape of the cutting edge of the cutting tool, the material of the workpiece, the cutting speed, the cutting thickness, and the cutting angle.

Images