Machine tool control device

Abstract

Provided is a feature with which it is possible to precisely achieve a desired surface roughness even if a cutting tool is replaced after the start of processing or if the shape of a blade edge of the cutting tool has changed, to improve the readability of a processing program, and to reduce the time and effort required in creating the processing program. Specifically, provided is a control device 1 for a machine tool that processes a workpiece W while moving the workpiece W relative to a cutting tool T, the machine tool control device 1 comprising: a surface roughness acquisition unit 11 that acquires, from a processing program, a target surface roughness set for a workpiece W being processed; a tool surface roughness information acquisition unit 12 that acquires tool surface roughness information relating to the surface roughness of the cutting tool T; and a feeding amount control unit 14 that, on the basis of the tool surface roughness information, determines feeding amount information relating to a feeding amount per relative rotation of the cutting tool T and the workpiece W such that the surface roughness of the workpiece W reaches the target surface roughness.

Description

Machine tool control device

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

[0002] BACKGROUND ART Conventionally, in cutting processing, a technique is known in which the feed amount of a spindle that moves a workpiece to be processed is specified in advance in a processing program or the like, and cutting processing is performed (see, for example, Patent Documents 1 and 2).

[0003] JP 2003-323204 A JP 2018-094690 A

[0004] One of the indicators of a machined workpiece is its surface roughness. Surface roughness is determined by the shape of the cutting edge of the cutting tool and the feed rate. Therefore, the feed rate of the spindle per unit time has been determined so that the machined workpiece can achieve the desired surface roughness.

[0005] However, if the cutting tool is changed during cutting or the shape of the cutting tool's cutting edge changes due to wear or the like, the cutting will continue at the same feed rate even though it is necessary to change the feed rate. If the feed rate is not appropriate for the conditions, there is a risk that the desired surface roughness will not be obtained.

[0006] Furthermore, in the method of setting a feed rate that reflects surface roughness in the machining program, it is difficult to grasp surface roughness, which is one of the indicators, from the machining program, and the conventional technology also had room for improvement in terms of readability.

[0007] Furthermore, the method of setting a feed rate that reflects surface roughness in the machining program requires the work of calculating a feed rate that will give the workpiece the desired surface roughness after machining, and then reflecting this in the machining program, which is time-consuming.

[0008] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a technology that can accurately obtain the desired surface roughness even if the cutting tool is changed after machining has begun or the shape of the cutting tool's cutting edge changes, and that can improve the readability of the machining program and reduce the effort required to create the machining program.

[0009] The present disclosure relates to a control device for a machine tool that performs machining while moving a cutting tool and a workpiece relative to each other, and includes a surface roughness acquisition unit that acquires a target surface roughness set for the workpiece to be machined from a machining program, a tool surface roughness information acquisition unit that acquires tool surface roughness information related to the surface roughness of the cutting tool, and a feed amount control unit that determines feed amount information related to the relative feed amount per rotation of the cutting tool and the workpiece based on the tool surface roughness information so that the surface roughness of the workpiece becomes the target surface roughness.

[0010] According to the present disclosure, it is possible to provide a technology that can accurately obtain the desired surface roughness even if the cutting tool is changed after machining has begun or the shape of the cutting tool's cutting edge changes, and that can improve the readability of the machining program and reduce the effort required to create the machining program.

[0011] FIG. 1 is a functional block diagram of a control device for a machine tool according to a first embodiment. FIG. 2 is a schematic diagram showing an example of cutting processing in which a target surface roughness is set. FIG. 3 is a diagram showing an example of a processing program. FIG. 4 is a diagram showing an example of a table of tool surface roughness information. FIG. 5 is a functional block diagram of a control device for a machine tool according to a second embodiment. FIG. 6 is a diagram for explaining swing cutting. FIG. 7 is a functional block diagram of a control device for a machine tool according to a third embodiment. FIG. 8 is a functional block diagram of a control device for a machine tool according to a fourth embodiment. FIG. 9 is a functional block diagram of a control device for a machine tool according to a fifth embodiment. FIG. 10 is a functional block diagram of a control device for a machine tool according to a sixth embodiment.

[0012] 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.

[0013] 1 is a functional block diagram of a machine tool control device 1 according to a first embodiment. The control device 1 according to the first embodiment controls a machine tool that performs machining while moving a cutting tool T and a workpiece relative to each other. The control device 1 cuts the workpiece with the tool by operating at least one spindle that rotates the cutting tool T and the workpiece relative to each other, and at least one feed axis that moves the cutting tool T relative to the workpiece.

[0014] 1 shows only the motor 3 that drives one feed axis and the cutting tool T for convenience. Furthermore, the cutting process according to this embodiment is not limited to a specific shape of the workpiece. That is, the present invention is applicable to cases where the workpiece has a tapered or arc-shaped portion on the machining surface, requiring multiple feed axes (Z-axis and X-axis), and cases where the workpiece is columnar or cylindrical, and only one specific feed axis (Z-axis) is sufficient.

[0015] As shown in Fig. 1, the machine tool control device 1 according to the first embodiment includes a first storage unit 10, a surface roughness acquisition unit 11, a second storage unit 20, a tool surface roughness information acquisition unit 12, and a feed rate control unit 14. 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, all 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 the control program stored in the memory.

[0016] 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 the machining program, machining conditions such as rotation speed are input to the machine tool control device 1 from the host computer.

[0017] The first storage unit 10 stores a machining program to be executed by the machine tool. The machining program includes workpiece machining conditions, etc. The workpiece machining conditions include the relative rotation speed of the workpiece and the cutting tool T around the central axis of the workpiece, the relative feed speed of the cutting tool T and the workpiece, position commands for the feed axes, target surface roughness, etc.

[0018] The target surface roughness is a desired surface roughness value set for the workpiece to be machined. Examples of surface roughness include at least one of the following: arithmetic mean roughness; maximum height, which is the maximum distance between peaks and valleys; maximum peak height, which is the maximum height from the mean line of the surface; maximum valley depth, which is the absolute value of the minimum height from the mean line of the surface; average height, which is the average height of the profile elements consisting of a pair of adjacent peaks and valleys; maximum cross-sectional height, which is the sum of the maximum peak height and the maximum valley depth of the profile elements; and load length ratio, which is the ratio of the load length of the profile elements at a predetermined cutting level (height % or μm) to the evaluation reference length. While typical surface roughness indices have been listed, they are not limited to these, and other surface roughness indices may also be used.

[0019] The surface roughness acquisition unit 11 acquires a target surface roughness from the machining program. In the first embodiment, the surface roughness acquisition unit 11 acquires the target surface roughness set in the machining program via the first storage unit 10, and outputs the acquired target surface roughness to the feed rate control unit 14.

[0020] The second storage unit 20 stores tool surface roughness information related to the surface roughness of the cutting tool T. The tool surface roughness information related to the surface roughness of the cutting tool T includes information specifying the shape of the cutting tool T (tool shape information). The tool shape information is, for example, information indicating the shape of the cutting edge of the cutting tool T, such as a nose R (mm) that indicates the diameter length of the cutting edge. The second storage unit 20 acquires and stores information specifying the shape of the cutting tool T from the machining program.

[0021] The tool surface roughness information relating to the surface roughness of the cutting tool T may be, for example, information (e.g., table data, relational equations, etc.) that represents the relationship between the feed rate and the surface roughness obtained when machining at that feed rate.

[0022] The tool surface roughness information relating to the surface roughness of the cutting tool T may be the information relating to the surface roughness of the cutting tool T itself, or may be indirect information such as a tool number for identifying tool shape information. In this case, a method may be used in which the second storage unit 20 stores in table form the numerical values ​​of the nose R (mm) corresponding to each tool number as indirect information, and the cutting tool T in use is identified by identifying the tool number in the machining program or the tool number of the connected cutting tool T.

[0023] The second memory unit 20 also stores information indicating tool surface roughness information related to the current surface roughness of the cutting tool T, which is acquired from the cutting tool T connected to the control device 1. By acquiring information indicating tool surface roughness information related to surface roughness from the cutting tool T, the second memory unit 20 also reflects changes in the tool surface roughness information related to the surface roughness of the cutting tool T after machining due to replacement or wear of the cutting tool T. The information indicating the tool surface roughness information related to the current surface roughness of the cutting tool T, which is acquired from the cutting tool T, may be the information related to the tool surface roughness itself, or may be indirect information such as a tool number. The change in the tool surface roughness information related to the surface roughness of the cutting tool T may be detected, for example, by including information identifying the tool surface roughness information related to the surface roughness of the cutting tool T in an external signal indicating that the cutting tool T has been replaced with a new one. The change in the tool surface roughness information related to the surface roughness of the cutting tool T may be detected, for example, by image processing using an imaging device, or by measuring the shape of the cutting edge using a contact or non-contact sensor.

[0024] The tool surface roughness information acquisition unit 12 acquires the tool surface roughness information of the cutting tool T from the second storage unit 20. The tool surface roughness information acquisition unit 12 may acquire the tool surface roughness information stored in the second storage unit 20, or may identify the tool surface roughness information from information identifying the cutting tool T stored in the second storage unit 20. The tool surface roughness information acquisition unit 12 outputs the acquired tool surface roughness information to the feed rate control unit 14.

[0025] The feed amount control unit 14 determines feed amount information relating to the relative feed amount per rotation between the cutting tool T and the workpiece, and controls the driving of the motor 3. The feed amount control unit 14 calculates the feed amount information based on the target surface roughness input from the surface roughness acquisition unit 11 and the tool surface roughness information input from the tool surface roughness information acquisition unit 12.

[0026] The feed amount information is information relating to the relative feed amount per revolution of the cutting tool T and the workpiece. The information relating to the feed amount is, for example, the feed amount F (mm / rev) per revolution of the spindle. The information relating to the feed amount may also be the spindle rotation speed (rev / min) and the feed amount (mm / min). Therefore, the feed amount control unit 14 may control both the feed axis motor and the spindle motor.

[0027] The input unit 15 inputs information related to processing in response to an operator's input operation on an input means (not shown), such as a keyboard or a touch panel. The information related to processing input by the input unit 15 is stored in the first storage unit 10 or the like, or input to each unit of the control device 1.

[0028] The display unit 16 displays various information relating to the machine tool, the control device 1, and machining.

[0029] Next, an example of the control process of the control device 1 according to the first embodiment will be described. Fig. 2 is a schematic diagram showing an example of cutting in which a target surface roughness is set. In the example of Fig. 2, "Rz: 3.0" is set in advance in the machining program as the target set roughness.

[0030] FIG. 3 is a diagram showing an example of a machining program. In the machining program of FIG. 3, the block "S2000 M03" is a description indicating forward rotation of the spindle. The block "T05" is a description indicating a tool number, which is information for identifying tool surface roughness information. Blocks beginning with "G00" or "G01," such as "G00 Z40.0 X20.0," are descriptions indicating behaviors and coordinates such as positioning and linear interpolation. Of these, "Rz3.0" in the block "G01 Z20.0 Rz3.0" is a description indicating the target surface roughness. When operation based on the machining program begins, the surface roughness acquisition unit 11 of the control device 1 begins analyzing the block "G01 Z20.0 Rz3.0" and acquires that the target surface roughness Rz is 3.0.

[0031] Fig. 4 is a diagram showing an example of a table of tool surface roughness information. In the example of Fig. 4, the information is stored in the second storage unit 20 in table format, and at least information on tool numbers T01 to T06 and the nose radii corresponding to each of the tool numbers T01 to T06 is stored. The tool surface roughness information acquisition unit 12 acquires tool surface roughness information based on the tool numbers described in the machining program and the table shown in Fig. 4. In this example, a nose radius of 0.4 (mm) corresponding to tool number "T05" included in the machining program is acquired as tool surface roughness information.

[0032] The method for acquiring the tool surface roughness information is not particularly limited. For example, the tool surface roughness information acquiring unit 12 may acquire the tool surface roughness information by referring to the tool number and table stored in the second storage unit 20, or may acquire tool surface roughness information that has been specified in advance based on the tool number and table from the second storage unit 20.

[0033] The feed rate control unit 14 determines the feed rate based on the target surface roughness acquired by the surface roughness acquisition unit 11 and the tool surface roughness information acquired by the tool surface roughness information acquisition unit 12. When the maximum depth Rz is used as an index of the target surface roughness, the feed rate control unit 14 calculates the feed rate using the following formula. In this example, when the target surface roughness h = 3.0 and nose R = 0.4 are substituted into the formula below, the feed rate F is approximately 0.098 (mm / rev).

[0034]

[0035] In formula (1), h represents the target surface roughness Rz (μm), f represents the feed rate per revolution of the spindle (mm / rev), and RE represents the nose R (mm) that indicates the shape of the cutting edge of the cutting tool T.

[0036] The feed amount control unit 14 controls the motor 3 at a feed amount based on the target surface roughness of the machining program until the target surface roughness of the machining program is updated. When the target surface roughness of the machining program is updated, the feed amount control unit 14 controls the motor 3 at a feed amount calculated based on the updated new target surface roughness.

[0037] Furthermore, the tool surface roughness information acquiring unit 12 monitors the state of the surface roughness of the cutting tool T. For this purpose, for example, it monitors whether the cutting tool T has been replaced. When replacement of the cutting tool T is detected, the tool surface roughness information acquiring unit 12 recalculates the feed amount information based on the surface roughness information of the replaced cutting tool T and the target surface roughness.

[0038] Furthermore, the shape of the blade of the cutting tool T is monitored as another means for monitoring the state of the surface roughness of the cutting tool T. When a change in the shape of the blade of the cutting tool T is detected, the tool surface roughness information acquisition unit 12 recalculates the feed amount information based on the tool shape information indicating the changed shape of the blade of the cutting tool T and the target surface roughness.

[0039] The control device 1 of the machine tool according to the first embodiment, which performs machining while moving the cutting tool T and the workpiece W relative to each other, provides the following effects.

[0040] The machine tool control device 1 according to this embodiment includes a surface roughness acquisition unit 11 that acquires a target surface roughness set for a workpiece W to be machined from a machining program; a tool surface roughness information acquisition unit 12 that acquires tool surface roughness information related to the surface roughness of a cutting tool T; and a feed amount control unit 14 that determines feed amount information related to the relative feed amount per rotation of the cutting tool T and the workpiece W based on the tool surface roughness information so that the surface roughness of the workpiece W matches the target surface roughness. This allows the target surface roughness to be set in the machining program, making it possible to control the feed amount based on the target surface roughness, improving the readability of the machining program, and reducing the effort required to create the machining program. Furthermore, even if the cutting tool T or the shape of the cutting edge of the cutting tool T (e.g., nose radius) changes after machining has begun, the feed amount information can be recalculated based on the target surface roughness and the surface roughness information of the cutting tool T, thereby enabling the desired surface roughness to be obtained with high accuracy.

[0041] Furthermore, in this embodiment, when the tool surface roughness information acquisition unit 12 detects a change in the tool surface roughness information of the cutting tool T, it acquires the changed tool surface roughness information, and the feed amount control unit 14 re-determines the feed amount information by reflecting the changed tool surface roughness information. This allows changes in the cutting edge of the cutting tool T due to replacement or wear of the cutting tool T to be quickly reflected in the feed amount information.

[0042] Furthermore, in this embodiment, until the next target surface roughness is acquired from the machining program, the surface roughness acquisition unit 11 continues to output the target surface roughness previously acquired from the machining program to the feed amount control unit 14. This makes the target surface roughness command modal information, facilitating machining programming.

[0043] Second Embodiment Figure 5 is a functional block diagram of a machine tool control device 1A according to a second embodiment. The control device 1A according to the second embodiment controls a machine tool that performs swing cutting while swinging a cutting tool T and a workpiece relative to each other. As shown in Figure 5, 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 third storage unit 30 and a swing condition acquisition unit 13, and in the control of a feed amount control unit 14A, but the other configurations are the same as those of the first embodiment.

[0044] 6 is a diagram illustrating swing cutting. In one example of swing cutting shown in FIG. 6, 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 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 to swing the cutting tool T and the workpiece W relative to each other in the feed direction while performing 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 that has been machined in the previous path, a missed swing called an air cut occurs, in which the cutting edge of the cutting tool T separates from the surface of the workpiece W, and chips are shredded.

[0045] The third storage unit 30 stores oscillation conditions for performing oscillation cutting. The oscillation conditions are acquired, for example, from a machining program. The oscillation conditions include information regarding the relative oscillation frequency per rotation between the cutting tool and the workpiece W and information regarding the oscillation amplitude relative to the relative feed rate per rotation between the cutting tool and the workpiece W. The information regarding the relative oscillation frequency per rotation between the cutting tool and the workpiece W includes an oscillation frequency magnification I (times), which indicates the oscillation frequency per rotation of the spindle. Furthermore, the information regarding the oscillation amplitude relative to the relative feed rate per rotation between the cutting tool and the workpiece W 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 directly specified, or may be calculated from the oscillation amplitude (mm), feed rate (mm / min), and spindle rotation speed S (1 / min) after specifying the oscillation amplitude (mm).

[0046] The oscillation condition acquisition unit 13 acquires the oscillation conditions and outputs them to the feed amount control unit 14A. The oscillation condition acquisition unit 13 acquires the oscillation conditions from the third storage unit 30. The oscillation condition acquisition unit 13 can also acquire oscillation conditions specified by an external signal or the like. The oscillation condition acquisition unit 13 outputs the acquired oscillation conditions to the feed amount control unit 14A.

[0047] The feed amount control unit 14A of the second embodiment calculates feed amount information based on the target surface roughness input from the surface roughness acquisition unit 11, the tool surface roughness information input from the tool surface roughness information acquisition unit 12, and the oscillation conditions input from the oscillation condition acquisition unit 13. The motor 3 is controlled based on the feed amount information calculated by the feed amount control unit 14A, and oscillation cutting is performed.

[0048] Furthermore, when the swing conditions in the machining program are updated, the updated swing conditions are stored in the third storage unit 30. The swing condition acquisition unit 13 monitors whether the swing conditions have changed. A change in the swing conditions occurs, for example, when the swing conditions of the machining program are changed, or when the swing conditions are changed by an external signal. When a change in the swing conditions is detected, the swing condition acquisition unit 13 recalculates the feed amount information based on the changed swing conditions, the tool surface roughness information, and the target surface roughness.

[0049] The machine tool control device 1A according to the second embodiment has the following advantages.

[0050] The machine tool control device 1A according to this embodiment further includes a surface roughness acquisition unit 11, a tool surface roughness information acquisition unit 12, and an oscillation condition acquisition unit 13 that acquires oscillation conditions for oscillation cutting, which oscillates the cutting tool T and workpiece W relative to one another. The feed rate control unit 14A determines feed rate information based on the tool surface roughness information and the oscillation conditions so that the surface roughness of the workpiece W matches the target surface roughness. This achieves the same effects as the control device 1 of the first embodiment. Even if the oscillation conditions change after machining begins, the feed rate information is recalculated based on the target surface roughness, the tool surface roughness information of the cutting edge of the cutting tool T, and the changed oscillation conditions. This allows the desired surface roughness to be accurately achieved even in oscillation cutting. This also reduces the effort required to determine the feed rate taking the oscillation conditions into account.

[0051] Furthermore, when the oscillation condition acquisition unit 13 of this embodiment detects a change in the oscillation conditions, it acquires the changed oscillation conditions, and the feed amount control unit 14A re-determines the feed amount information by reflecting the changed oscillation conditions. This allows the change in the oscillation conditions after the start of processing to be quickly reflected in the feed amount information.

[0052] [Third embodiment] Figure 7 is a functional block diagram of a machine tool control device 1B according to a third embodiment. The control device 1B according to the third embodiment controls a machine tool that performs cutting processing while moving a cutting tool T and a workpiece relative to each other. As shown in Figure 7, 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 specified feed amount acquisition unit 17 and in the control of a feed amount control unit 14B, but the other configurations are the same as those of the first embodiment.

[0053] The specified feed amount acquisition unit 17 acquires specified feed amount information that specifies information about the relative feed amount per rotation between the cutting tool T and the workpiece W. The specified feed amount information is a preset numerical value, and is a numerical value in the same unit as the feed amount information. The specified feed amount information is set by being written in the machining program or input from the input unit 15.

[0054] For example, the designated feed amount acquisition unit 17 acquires the designated feed amount when designated feed amount information is described in the machining program in the first storage unit 10. Upon acquiring the designated feed amount information, the designated feed amount acquisition unit 17 outputs the designated feed amount information to the feed amount control unit 14B.

[0055] When the feed amount control unit 14B of the third embodiment acquires designated feed amount information from the designated feed amount acquisition unit 17, the designated feed amount information takes priority over the feed amount information calculated based on the target surface roughness and the tool surface roughness information. Therefore, the motor 3 is controlled based on the designated feed amount information.

[0056] The machine tool control device 1B according to the third embodiment provides the following effects.

[0057] When the machine tool control device 1B according to this embodiment acquires designated feed amount information specifying information relating to the relative feed amount per rotation between the cutting tool T and the workpiece W, it controls the relative feed amount per rotation between the cutting tool T and the workpiece W based on the designated feed amount information. This makes it possible to flexibly respond to cases where it is better to specify a feed rate, such as when there is a block that is not to be machined.

[0058] The designated feed amount acquisition unit 17 of the third embodiment may be added to the configuration of the second embodiment that performs oscillating cutting. In this case, when the feed amount control unit 14B acquires designated feed amount information, it controls the motor 3 by giving priority to the designated feed amount information.

[0059] [Fourth embodiment] Fig. 8 is a functional block diagram of a machine tool control device 1C according to a fourth embodiment. As shown in Fig. 8, the machine tool control device 1C according to the fourth embodiment differs from the machine tool control device 1 according to the first embodiment in that it further includes a deviation correction value acquisition unit 18 and in the control of a feed amount control unit 14C, but the other configurations are the same as those of the first embodiment.

[0060] The deviation correction value acquisition unit 18 acquires a deviation correction value that corrects the deviation between the theoretical value and the measured value of surface roughness. The deviation correction value is calculated, for example, based on the machining conditions and the like acquired from the first storage unit 10. The machining conditions are calculated based on the machining conditions and the like including at least one of the material of the cutting tool cutting edge, the shape of the cutting tool cutting edge, the material of the workpiece W, the cutting speed, the cutting depth, and the cutting angle. The deviation correction value may also be calculated based on machine parameters as needed. The deviation correction value acquisition unit 18 outputs the acquired deviation correction value to the feed rate control unit 14C.

[0061] The feed amount control unit 14C of the fourth embodiment calculates feed amount information based on the target surface roughness input from the surface roughness acquisition unit 11, the tool surface roughness information input from the tool surface roughness information acquisition unit 12, and the deviation correction value acquired from the deviation correction value acquisition unit 18. The motor 3 is controlled based on the feed amount information calculated by the feed amount control unit 14C, and cutting is performed.

[0062] The deviation correction value acquisition unit 18 may also use machine learning such as supervised learning. For example, a learning model may be constructed using a large amount of data set that receives feed amount information related to the machining conditions and the feed amount and outputs the actual surface roughness, and the deviation correction value may be determined based on the surface roughness that is the output result of the learning model.

[0063] According to the machine tool control device 1C according to the fourth embodiment, the following effects are achieved.

[0064] The machine tool control device 1C according to this embodiment further includes a deviation correction value acquisition unit 18 that acquires a deviation correction value for correcting the deviation between the theoretical value of surface roughness and the measured value of the actual surface roughness of the workpiece W, and the feed amount control unit 14C determines the feed amount information taking the deviation correction value into account. As a result, the feed amount information is determined taking the deviation between the theoretical value of surface roughness and the actual surface roughness value into account, and it is possible to perform machining with even higher precision and achieve the desired surface roughness.

[0065] The deviation correction value acquisition unit 18 of the fourth embodiment may be added to the configuration of the second embodiment, which performs swing cutting. In this case, it is preferable that the deviation correction value acquisition unit 18 determines the feed amount information by taking into account swing conditions in addition to the machining conditions. When machine learning is combined, it is preferable to add swing conditions to the input of the data set.

[0066] Fifth Embodiment Fig. 9 is a functional block diagram of a machine tool control device 1D according to a fifth embodiment. As shown in Fig. 9, the machine tool control device 1D according to the fifth embodiment differs from the machine tool control device 1 according to the first embodiment in that it further includes a surface roughness correction value acquisition unit 21 and a surface roughness determination unit 22, and in the control of a feed amount control unit 14D, but the other configurations are the same as those of the first embodiment.

[0067] The surface roughness correction value acquisition unit 21 acquires a surface roughness correction value for correcting the target surface roughness. The surface roughness correction value acquisition unit 21 is a magnification (correction coefficient) that is specified, for example, by the operator operating an input means such as a dial on the input unit 15 or by operating an external computer. The operator can adjust the surface roughness by changing the target surface roughness to 90%, 110%, etc., with the target surface roughness being 100% as the standard.

[0068] The surface roughness determination unit 22 corrects the target surface roughness input from the surface roughness acquisition unit 11 using the surface roughness correction value input from the surface roughness correction value acquisition unit 21 , and outputs the corrected value to the feed amount control unit 14 .

[0069] The feed amount control unit 14D of the fifth embodiment calculates feed amount information based on the corrected target surface roughness input from the surface roughness determination unit 22 and the tool surface roughness information input from the tool surface roughness information acquisition unit 12. The motor 3 is controlled based on the feed amount information calculated by the feed amount control unit 14D, and cutting is performed.

[0070] The machine tool control device 1D according to the fifth embodiment has the following advantages.

[0071] The machine tool control device 1D according to this embodiment further includes a surface roughness correction value acquisition unit 21 that acquires a surface roughness correction value for correcting a target surface roughness, and a surface roughness determination unit 22 that determines a surface roughness based on the target surface roughness acquired by the surface roughness acquisition unit 11 and the surface roughness correction value acquired by the surface roughness correction value acquisition unit 21, and a feed amount control unit 14D determines feed amount information so as to achieve the surface roughness determined by the surface roughness determination unit 22. This allows the operator to adjust the accuracy of the surface roughness after machining without changing the machining program.

[0072] Furthermore, the surface roughness correction value acquisition unit 21 and the surface roughness determination unit 22 of the fifth embodiment may be added to the configurations of other embodiments, such as the second embodiment in which oscillating cutting is performed.

[0073] [Sixth embodiment] Fig. 10 is a functional block diagram of a machine tool control device 1E according to a sixth embodiment. As shown in Fig. 10, the machine tool control device 1E according to the sixth embodiment differs from the machine tool control device 1 according to the first embodiment in that it further includes an output processing unit 23, but the other configurations are the same as those of the first embodiment.

[0074] The output processing unit 23 executes display processing for outputting the feed amount information determined by the feed amount control unit 14 to the display unit 16. The display unit 16 displays on the screen the feed amount information that has been subjected to display processing by the output processing unit 23. The display unit 16 displays, for example, the feed amount F (mm / rev) per spindle rotation, the spindle rotation speed (rev / min), the feed amount (mm / min), and the like on the screen as feed amount information.

[0075] The machine tool control device 1E according to the sixth embodiment has the following advantages.

[0076] The machine tool control device 1E according to this embodiment further includes an output processing unit 23 that outputs feed amount information determined by the feed amount control unit 14 to the display unit 16. This allows the operator to check the feed amount information displayed on the display screen of the display unit 16, making it easy to check safety and production plans.

[0077] Furthermore, the output processing unit 23 of the sixth embodiment may be added to the configuration of other embodiments, such as the second embodiment in which oscillating cutting is performed.

[0078] 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.

[0079] 1, 1A, 1B, 1C, 1D, 1E Machine tool control device 11 Surface roughness acquisition unit 12 Tool surface roughness information acquisition unit 13 Swing condition acquisition unit 14, 14A, 14B, 14C, 14D Feed amount control unit 16 Display unit 17 Specified feed amount acquisition unit 18 Deviation correction value acquisition unit 21 Surface roughness correction value acquisition unit 22 Surface roughness determination unit 23 Output processing unit

Claims

1. A control device for a machine tool that performs machining while moving a cutting tool and a workpiece relatively, comprising: a surface roughness acquisition unit that acquires a target surface roughness set for the workpiece to be machined from a machining program; a tool surface roughness information acquisition unit that acquires tool surface roughness information relating to the surface roughness of the cutting tool; and a feed amount control unit that determines feed amount information regarding the relative feed amount per rotation of the cutting tool and the workpiece based on the tool surface roughness information so that the surface roughness of the workpiece becomes the target surface roughness.

2. A swing condition acquisition unit that acquires swing conditions for swing cutting in which the cutting tool and the workpiece are swung relatively to each other, The feed amount control unit is determining the feed amount information based on the tool surface roughness information and the swing conditions so that the surface roughness of the workpiece becomes the target surface roughness; The control device for a machine tool according to claim 1.

3. When the oscillation condition acquisition unit detects a change in the oscillation condition, the oscillation condition acquisition unit acquires the oscillation condition after the change; The control device for a machine tool according to claim 2 , wherein the feed amount control section redetermines the feed amount information by reflecting the changed oscillation conditions.

4. the tool surface roughness information acquisition unit, when detecting a change in the tool surface roughness information of the cutting tool, acquires the tool surface roughness information after the change; 4. The control device for a machine tool according to claim 1, wherein the feed amount control unit redetermines the feed amount information by reflecting the changed tool surface roughness information.

5. The control device for a machine tool according to any one of claims 1 to 3, wherein the surface roughness acquisition unit continues to output the target surface roughness previously acquired from the machining program to the feed amount control unit until the next target surface roughness is acquired from the machining program.

6. 4. The control device for a machine tool according to claim 1, wherein when the feed amount control unit acquires specified feed amount information specifying information regarding the relative feed amount per rotation between the cutting tool and the workpiece, it controls the relative feed amount per rotation between the cutting tool and the workpiece based on the specified feed amount information.

7. A deviation correction value acquisition unit that acquires a deviation correction value that corrects a deviation between a theoretical value of surface roughness and an actual value of surface roughness of the workpiece, The control device for a machine tool according to claim 1 , wherein the feed amount control unit determines the feed amount information by taking into account the deviation correction value.

8. a surface roughness correction value acquisition unit that acquires a surface roughness correction value for correcting the target surface roughness; a surface roughness determination unit that determines a surface roughness based on the target surface roughness acquired by the surface roughness acquisition unit and the surface roughness correction value acquired by the surface roughness correction value acquisition unit, 4. The control device for a machine tool according to claim 1, wherein the feed amount control unit determines the feed amount information so as to achieve the surface roughness determined by the surface roughness determination unit.

9. 4. The control device for a machine tool according to claim 1, further comprising an output processing section that outputs the feed amount information determined by the feed amount control section to a display section.