Control system of a machine tool

Abstract

Control system (100) of a machine tool machining a workpiece (W), the control system (100) comprising: a control device (17) which controls a drive axis of the machine tool (10) based on speed control data; a machined surface measuring device (20) that measures a machined surface of the workpiece (W); and an analysis device (30) which analyses defects on the machined surface of the workpiece (W), wherein the analysis device (30) comprises: a first retrieving section (31) which retrieves the chronological speed control data when machining the workpiece (W) from the control device (17); a second retrieving section (32) that retrieves spatial measurement data on a machined surface measured by the machined surface measuring device (20) after machining the workpiece (W); a data association processing section (34) that associates the chronological speed control data retrieved by the first retrieval section (31) with the spatial measurement data relating to a machined surface retrieved by the second retrieval section (32); a machined surface error detection section (35) that detects the errors on the machined surface of the workpiece (W) and their positions based on the machined surface spatial measurement data retrieved by the second retrieving section (32); an identification section (36) which, based on the speed control data and machined surface measurement data assigned by the data assignment processing section (34), identifies the speed control data on the defect positions corresponding to the machined surface measurement data to the defect positions detected by the machined surface defect detection section (35); a defect pitch detecting section (37) that detects a pitch of the defects detected by the machined surface defect detecting section (35); and a calculation section (38) which determines a speed in a direction of machining based on the speed control data on the defect positions identified by the identification section (36), and calculates a frequency of vibrations of the machine tool (10) causing the defects based on the determined speed and the distance of the defects detected by the defect distance detection section (37).

Description

BACKGROUND OF THE INVENTIONField of the Invention

[0001] The present invention relates to the control system of a machine tool that machines a workpiece. Related technology

[0002] A machine tool machines a workpiece by moving at least either the workpiece (the object to be machined) or a tool along predetermined drive axes. In other words, the machine tool machines the workpiece while changing the relative position of the workpiece and the tool.

[0003] US 5 768 137 A describes a precision positioning system for the renewal and repair of rails and guides of large, heavy machines.

[0004] During machining of the workpiece, vibrations may be transmitted to a main axis head holding a tool or a table holding the workpiece, causing the tool or workpiece to vibrate. Vibrations are generated, for example, when the moving direction of the main axis head or the table is changed during machining. Vibrations are also transmitted from a fan motor in an inverter or the like in the machine tool, various machines outside the machine tool, or the like. When the tool or the workpiece is vibrated by the vibrations described above, a stripe pattern (defect) may appear on the machined surface of the workpiece. In other words, streaks or stripes may appear at a predetermined pitch.

[0005] Patent Documents 1 and 2 disclose technologies in which a stripe pattern (defect) on the machined surface of a workpiece is detected based on the movement trajectory of the front end of a tool when machining a workpiece. Patent Document 1: Unexamined Japanese Patent Application Publication No. 2016-57843 Patent Document 2: Unexamined Japanese Patent Application, Publication No. 2017-13178 SUMMARY OF THE INVENTION

[0006] The inventors of the present application, et al., have attempted an approach different from the technologies disclosed in Patent Documents 1 and 2 for detecting defects on the machined surface of a workpiece. Specifically, as another method for detecting defects on the machined surface of the workpiece after machining, an optical sensor or the like is used to detect an image of the machined surface of the workpiece, image processing is performed on the data of the detected image, and the defects (the streaks or striations) on the machined surface are thereby detected. Then, based on the distance of the defects detected from the image data, the frequency of vibrations causing the defects is estimated.

[0007] However, during machining of the workpiece, the machining speed may change. In this case, the spacing of the defects (the streaks or striations) changes, making it difficult to estimate the frequency of the vibrations causing the defects.

[0008] Therefore, it is an object of the present invention to provide the control system of a machine tool by which the frequency of vibrations causing defects on the machined surface of a workpiece in machining in which the machining speed changes during machining of the workpiece can be estimated.

[0009] (1) A control system (for example, a machine tool numerical control system 100, which will be described later) of a machine tool according to the present invention that machines a workpiece (for example, a workpiece W, which will be described later) includes: a control device (for example, a numerical control device 17, which will be described later) that controls a drive axis of the machine tool (for example, a machine tool 10, which will be described later) based on speed control data; a machined surface measuring device (for example, a machined surface measuring device 20, which will be described later) that measures a machined surface of the workpiece; andand an analysis device (for example, a machined surface error analysis device 30, described later) that analyzes errors on the machined surface of the workpiece, the analysis device comprising: a first retrieval section (for example, a drive axis control data retrieval section 31, described later) that retrieves the chronological speed control data during machining of the workpiece from the control device; a second retrieval section (for example, a machined surface measurement data retrieval section 32, described later) that retrieves spatial measurement data of a machined surface measured by the machined surface measurement device after machining of the workpiece;a data association processing section (for example, a data association processing section 34, described later) that associates the chronological speed control data retrieved by the first retrieval section with the spatial measurement data of a machined surface retrieved by the second retrieval section; a machined surface defect detection section (for example, a machined surface defect detection section 35, described later) that detects the defects on the machined surface of the workpiece and their positions based on the spatial measurement data of a machined surface retrieved by the second retrieval section;an identification section (for example, a defect position control data identification section 36, described later) that identifies, based on the speed control data and machined surface measurement data associated with each other by the data association processing section, the defect position speed control data corresponding to the machined surface measurement data and the defect positions detected by the machined surface defect detection section; a defect pitch detection section (for example, a defect pitch detection section 37, described later) that detects a pitch of the defects detected by the machined surface defect detection section;and a calculation section (for example, a vibration frequency calculation section 38 described later) that determines a speed in a machining direction based on the speed control data on the defect positions identified by the identification section, and calculates the frequency of vibrations of the machine tool causing the defects based on the determined speed and the distance of the defects detected by the defect distance detection section;

[0010] (2) In the control system of the machine tool according to (1), the data matching processing section may: detect a machining start position and a machining completion position as an edge position of the workpiece based on a change in the chronological speed control data to generate a first workpiece shape image; detect an edge position of the workpiece based on the spatial measurement data of a machined surface to generate a second workpiece shape image; and match the chronological speed control data with the spatial measurement data of a machined surface to superimpose the edge position of the first workpiece shape image and the edge position of the second workpiece shape image.

[0011] (3) In the control system of the machine tool according to (1), the data allocation processing section may: detect a machining start position and a machining completion position as an edge position of the workpiece based on a change in a value obtained by subtracting an acceleration / deceleration change part from the chronological speed control data to generate a first workpiece shape image; detect an edge position of the workpiece based on the spatial measurement data of a machined surface to generate a second workpiece shape image; and associate the chronological speed control data with the spatial measurement data of a machined surface to superimpose the edge position of the first workpiece shape image and the edge position of the second workpiece shape image.

[0012] (4) In the control system of the machine tool according to (1), the first retrieving section may retrieve, from the control device, information on the position of the drive axis of the machine tool, which is chronological position control data associated with the chronological speed control data in machining the workpiece, and the data association processing section may: generate a first image of the shape of a workpiece based on the chronological position control data; generate a second image of the shape of a workpiece based on the spatial measurement data of a machined surface; associate the chronological position control data with the spatial measurement data of a machined surface to superimpose the first image of the shape of a workpiece and the second image of the shape of a workpiece;and associate the chronological speed control data with the chronological position control data to associate the chronological speed control data with the spatial measurement data relating to a machined surface;

[0013] (5) In the control system of the machine tool according to (4), the chronological position control data may be machine coordinate information, and the spatial measurement data on a machined surface may be machine coordinate information calculated based on machine coordinates of the machined surface measuring device.

[0014] (6) In the control system of the machine tool according to any one of (1) to (5), the analysis device may further include a setting section (for example, a setting section 39 described later) that sets a filter or a machining condition of the control device to reduce the vibration based on the frequency of the vibrations calculated in the calculation section.

[0015] (7) In the control system of the machine tool according to (6), the setting section may set a characteristic of the filter in a control circuit of the control device or set the filter in the control circuit of the control device.

[0016] (8) In the control system of the machine tool according to (6), the setting section may set a parameter for determining a speed, an acceleration or a jerk of the drive axis in the control device to set the machining condition.

[0017] (9) In the control system of the machine tool according to any one of the items (1) to (8), the defects on the machined surface of the workpiece may be streaks or striations.

[0018] (10) In the control system of the machine tool according to any one of (1) to (9), the speed control data may be a speed command value or a speed feedback value.

[0019] By the present invention, it is possible to provide the control system of a machine tool by which the frequency of vibrations causing defects on the machined surface of a workpiece in machining in which the machining speed changes during machining of the workpiece can be estimated. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view showing an example of the configuration of a machine tool according to the present embodiment of the present invention. Fig. 2 is a diagram showing the configuration of a numerical control system of the machine tool according to the embodiment of the present invention. Fig. 3 is a flowchart showing a machined surface error analysis processing executed by the machined surface error analysis apparatus of the numerical control system of the machine tool according to the embodiment of the present invention. Fig. Figure 4 is a diagram schematically showing data matching processing. Fig. 5 is a diagram schematically showing identification processing on the control data for the position of defects. Fig. 6A is a schematic view showing defects (streaks or streaks) when the workpiece is viewed from a direction perpendicular to the machined surface. Fig. 6B is a schematic view showing the defects (the streaks or striations) when the workpiece is viewed from a direction parallel to the machined surface. Fig. 7A is a schematic view showing an example of the defects (the streaks or striations) when the workpiece is viewed from the direction perpendicular to the machined surface. Fig. 7B is a schematic view showing another example of the defects (the streaks or striations) when the workpiece is viewed from the direction perpendicular to the machined surface. Fig. 7C is a schematic view showing another example of the defects (the streaks or striations) when the workpiece is viewed from the direction perpendicular to the machined surface. DETAILED DESCRIPTION OF THE INVENTION

[0020] Examples of embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings, like or corresponding portions are designated by the same reference numerals. (machine tool)

[0021] First, an example of a machine tool in a numerical control system according to the embodiment of the present invention will be described. Fig. 1 is a perspective view showing an example of the configuration of the machine tool according to the present embodiment of the present invention. This machine tool 10 is a machine tool that performs machining (removal). The machine tool in the numerical control system according to the present invention is not limited to this machine tool and can be any industrial machine.

[0022] The Fig. The machine tool 10 shown in FIG. 1 includes a head 2, a support member 3 that movably supports the head 2, a support column 4 that movably supports the support member 3, a stand 5 that supports the support column 4, and a table 6. A tool T such as an end mill is fixed to the head 2, and a workpiece W is mounted on the table 6. The machine tool 10 includes a drive device (not shown) and a numerical control device (not shown).

[0023] The drive device includes servo motors, which will be described later. The drive device moves the column 5 in the X-axis direction (arrow X), the table 6 in the Y-axis direction (arrow Y), and the holding member 3 in the Z-axis direction (arrow Z). Furthermore, the drive device rotates the tool T with respect to the head 2 in the A-axis direction (arrow A) and the head 2 with respect to the holding member 3 in the B-axis direction (arrow B).

[0024] The numerical control device controls the drive device to control the drive axes formed by the three directly moving axes (the X-axis, the Y-axis, and the Z-axis) and the two rotary axes (the A-axis and the B-axis), thereby controlling the relative position of the tool T with respect to the workpiece W and its posture. In this way, the machine tool 10 machines the workpiece W while changing the relative position of the tool T with respect to the workpiece W and its posture.

[0025] When machining the workpiece W in the machine tool 10 described above, vibrations may be transmitted to the head 2 holding the tool T or the table 6 holding the workpiece W, causing the tool T or the workpiece W to vibrate. For example, vibrations are generated when the movement direction of the head 2 or the table 6 is changed during machining. If the tool T or the workpiece W is vibrated by the vibrations of the machine tool 10 described above, defects (streaks or streaks) may occur on the machined surface of the workpiece W.

[0026] The defects (the streaks or striations) described above can be detected to detect an image of the machined surface of the workpiece W and to perform image processing on the data of the detected image after machining the workpiece W using an optical sensor or the like. Then, based on the pitch of the defects detected from the image data, the frequency of the vibrations of the machine tool 10 causing the defects can be estimated.

[0027] However, during machining of the workpiece W, a machining speed may change. In this case, the pitch of the defects (the streaks or striations) changes, making it difficult to estimate the frequency of the vibrations of the machine tool 10 that cause the defects.

[0028] The present invention relates to the numerical control system of the machine tool by which the frequency of the vibrations of the machine tool 10 causing the defects on the machined surface of the workpiece W can be estimated even in machining in which the machining speed changes during machining of the workpiece. (Numerical control system of the machine tool)

[0029] Next, the numerical control system of the machine tool according to the embodiment of the present invention will be described. Fig. Fig. 2 is a diagram showing the configuration of the numerical control system of the machine tool according to the embodiment of the present invention. The numerical control system 100 of the Fig. 2 comprises the machine tool 10 described above, a machined surface measuring device 20 and a machined surface error analyzing device 30.

[0030] The machine tool 10 includes a plurality of servomotors M1 to M5 in the above-described drive device, encoders (position / speed detectors) 11 to 15 provided in the servomotors M1 to M5, current detectors CT1 to CT5, a measuring scale (position detector) 16, and the numerical control device (CNC) 17. In Fig. 2, only the configuration of the machine tool 10 relating to the features of the present invention is shown, and the illustration of the remaining configuration is omitted.

[0031] The servomotors M1 to M5 each drive the above-described drive axes (the X-axis, the Y-axis, the Z-axis, the A-axis, and the B-axis) under the control of the numerical control device 17. The encoders 11 to 15 each detect the rotational positions of the servomotors M1 to M5 and send the detected rotational positions as position feedback values ​​to the numerical control device 17. The encoders 11 to 15 each detect the rotational speeds of the servomotors M1 to M5 and send the detected rotational speeds as speed feedback values ​​to the numerical control device 17.

[0032] The current detectors CT1 to CT5 respectively detect the drive current values ​​of the servo motors M1 to M5 and send the detected drive current values ​​as current feedback values ​​(actual current values, actual torque values) to the numerical control device 17.

[0033] For example, a measuring scale 16 is provided in the table 6 on which the above-described workpiece W is mounted. The measuring scale 16 detects the position of the workpiece and sends the detected position as a position feedback value to the numerical control device 17.

[0034] The numerical controller 17 generates torque command values ​​(current command values) for the drive axes based on position command values ​​(movement command values) of the drive axes based on a machining program related to machining the workpiece W, the position feedback value from the measuring scale 16 or the position feedback values ​​from the encoders 11 to 15, the speed feedback values ​​from the encoders 11 to 15, and the current feedback values ​​from the current detectors CT1 to CT5, and drives the servomotors M1 to M5 using these torque command values.

[0035] Specifically, the numerical control device 17 includes a position command generation section, a speed command generation section, and a torque command generation section. The position command generation section generates the position command values ​​(the motion command values) for the drive axes based on the machining program stored in a storage section. The speed command generation section generates speed command values ​​for the drive axes based on differences between the position command values ​​and the position feedback values. The torque command generation section generates the torque command values ​​(the current command values) based on differences between the speed command values ​​and the speed feedback values.The numerical control device 17 generates the drive currents for the drive axes based on differences between the torque command values ​​(the current command values) and the current feedback values.

[0036] The numerical control device 17 is constituted, for example, by a computing processor such as a DSP (digital signal processor) or an FPGA (field-programmable gate array). Various types of functions of the numerical control device 17 are realized by executing predetermined software (programs, applications) stored in the memory section (not shown). The various types of functions of the numerical control device 17 can be realized through the cooperation of hardware and software or solely by hardware (an electronic circuit).

[0037] The machined surface measuring device 20 is a device that measures the workpiece W to measure the machined surface of the workpiece W. Specific examples of the machined surface measuring device 20 include an optical sensor, an optical microscope, a laser microscope, or a three-dimensional coordinate measuring machine. The machined surface measuring device 20 sends the measured image data or position data of the workpiece W to the machined surface defect analysis device 30. The machined surface measuring device 20 is provided, for example, in a measuring stage or a rework stage outside the machine tool 10 or a final stage of a robot. The machined surface measuring device 20 may be integrated into the machine tool 10.

[0038] The machined surface defect analysis device 30 is a device that analyzes the defects (the streaks or striations) on the machined surface of the workpiece W. Specifically, the machined surface defect analysis device 30 estimates the frequency of vibrations that cause the defects (the streaks or striations).The machined surface defect analysis apparatus 30 includes a drive-axle control data retrieval section 31 (a first retrieval section), a machined surface measurement data retrieval section 32 (a second retrieval section), a storage section 33, a data allocation processing section 34, a machined surface defect detection section 35, a defect position control data identification section 36, a defect distance detection section 37, a vibration frequency calculation section 38, and a setting section (a determination section) 39.

[0039] The drive-axis control data retrieval section 31 retrieves the chronological drive-axis control data during the machining of the workpiece W from the numerical control device 17. Specifically, the drive-axis control data retrieval section 31 retrieves speed control data (speed command values ​​or speed feedback values ​​acquired from the encoders 11 to 15) as drive-axis control data.

[0040] The machined surface measurement data retrieval section 32 retrieves the spatial measurement data of a machined surface measured by the machined surface measuring device 20 after machining the workpiece W. Specifically, the machined surface measurement data retrieval section 32 retrieves the three-dimensional image data or the position data (the coordinate data) as the machined surface measurement data. The machined surface measurement data retrieval section 32 may retrieve two-dimensional image data as the machined surface measurement data.

[0041] The storage section 33 stores the chronological speed control data retrieved by the drive axle control data retrieval section 31 and the spatial measurement data of a machined surface measured by the machined surface measuring device 20. The storage section 33 is, for example, a rewritable memory such as an EEPROM.

[0042] The data association processing section 34 associates the chronological speed control data with the spatial measurement data stored in the storage section 33 to a machined surface. The details of the data association processing will be described later.

[0043] The machined surface defect detection section 35 detects the defects (the streaks or striations) of the machined surface of the workpiece W and their positions based on the spatial measurement data of a machined surface stored in the storage section 33.

[0044] The defect position control data identifying section 36 identifies, based on the speed control data and machined surface measurement data associated with each other by the data association processing section 34, the defect position speed control data corresponding to the machined surface measurement data and the defect positions detected by the machined surface defect detection section 35. The defect position control data identifying section 36 also associates the direction of the defects (the streaks or striations) of the machined surface with the machining direction based on the chronological defect position speed control data.

[0045] The defect spacing section 37 detects the spacing of the defects (the streaks or bands) detected by the machined surface defect detection section 35.

[0046] The vibration frequency calculation section 38 determines a speed in the machining direction based on the speed control data of the defect positions identified by the defect position control data identification section 36. Then, based on the determined speed v and the distance d of the defects (the streaks or striations) detected by the defect distance detection section 37, the vibration frequency calculation section 38 calculates the frequency f of the vibrations of the machine tool 10 causing the defects using the following formula (1). f=v / d

[0047] The adjustment section 39 adjusts the filter or the machining condition of the numerical controller 17 to reduce the vibration based on the vibration frequency calculated by the vibration frequency calculation section 38. For example, the adjustment section 39 adjusts the characteristic of the filter (e.g., a low-pass filter, a high-pass filter, or a band-pass filter) or the gain of a control circuit formed by the position command generation section, the speed command generation section, and the torque command generation section in the numerical controller 17. Alternatively, the adjustment section 39 adjusts a filter (e.g., a notch filter or a band-stop filter) in the control circuit of the numerical controller 17.Alternatively, the setting section 39 sets the machining condition (the speed, the acceleration, or the jerk) of the numerical control device 17. The details of the setting processing of the setting section 39 will be described later.

[0048] Here, the defects (the streaks or striations) caused by vibrations occur in a direction that intersects the machining direction. Therefore, the adjustment section 39 executes adjustment processing based on the direction of the defects (the streaks or striations) of the machined surface and the machining direction assigned by the defect position control data identification section 36 when the direction of the defects (the streaks or striations) of the machined surface intersects the machining direction.

[0049] The machined surface defect analysis device 30 is formed, for example, by a computing processor such as a DSP (digital signal processor) or an FPGA (field programmable gate array). The various types of functions of the machined surface defect analysis device 30 are realized by executing predetermined software (programs, applications) stored in the memory section (not shown). The various types of functions of the machined surface defect analysis device 30 can be realized through the cooperation of hardware and software or exclusively through hardware (an electronic circuit).

[0050] The various types of functions of the machined surface defect analysis device 30 can be implemented in the numerical control device 17 of the machine tool 10.

[0051] Next, with reference to the Fig. 3 to 7C, the machined surface error analysis processing executed by the machined surface error analysis device 30 of the numerical control system 100 of the machine tool according to the present embodiment will be described. Fig. 3 is a flowchart showing the processing for analyzing machined surface errors executed by the machined surface error analyzing device 30 of the numerical control system 100 of the machine tool according to the present embodiment. Fig. Figure 4 is a diagram schematically showing the data mapping processing. Fig. 5 is a diagram schematically showing the identification processing on the control data of the error positions. Fig. 6A is a schematic view showing the defects (the streaks or striations) when the workpiece W is viewed from a direction perpendicular to the machined surface, and Fig. Figure 6B is a schematic view showing the defects (the streaks or striations) when the workpiece W is viewed from a direction parallel to the machined surface. Fig. 7A to 7C are schematic views showing examples of defects (streaks or streaks) when the workpiece W is viewed from the direction perpendicular to the machined surface.

[0052] When the workpiece W is machined by the machine tool 10, the numerical control device 17 controls the drive axes based on the position command values, the speed command values, and the torque command values ​​(the current command values) of the drive axes, the position feedback values ​​from the measuring scale 16 (or the position feedback values ​​from the encoders 11 to 15), the speed feedback values ​​from the encoders 11 to 15, and the current feedback values ​​(the actual current values ​​and the actual torque values) from the current detectors CT1 to CT5, and thereby controls the relative position of the tool T with respect to the workpiece W and its posture.

[0053] When machining the workpiece W, the drive-axis control data retrieval section 31 retrieves the chronological speed control data (the speed command values ​​or speed feedback values ​​detected by the encoders 11 to 15) from the numerical control device 17 in step S11 and stores them in the storage section 33.

[0054] When the machining of the workpiece W is completed, the machined surface measuring device 20 measures the machined surface of the workpiece W. Here, in step S12, the machined surface measurement data retrieval section 32 retrieves the spatial machined surface measurement data from the machined surface measuring device 20 and stores it in the storage section 33. Specifically, the machined surface measurement data retrieval section 32 retrieves the three-dimensional image data or the position data (the coordinate data) as the machined surface measurement data.

[0055] Subsequently, in step S13, the data matching processing section 34 matches the chronological speed control data with the spatial measurement data of a machined surface stored in the storage section 33. Here, after machining the workpiece, the data of an image detected by an optical sensor is, for example, three-dimensional data, whereas the speed control data obtained by the numerical controller 17 during machining of the workpiece W is chronological data, making it difficult to match these types of data. The present inventors et al. use the following method to match these types of data.

[0056] For example, the machine tool machines the entire workpiece W while reciprocating the tool T with respect to the workpiece W. When the tool T comes into contact with the workpiece W and when the tool T is removed from the workpiece W, the speed command values ​​and the speed feedback values ​​change. In this way, the point of change in the speed command values ​​or the point of change in the speed feedback values ​​is detected, and therefore, it is possible to detect the edge position of the workpiece W, that is, the outline of the workpiece W.

[0057] Since the speed command values ​​and the speed feedback values ​​are also changed according to acceleration / deceleration, in the present embodiment, a value obtained by subtracting an acceleration / deceleration change part from the speed command values ​​and the speed feedback values ​​is used. This prevents a reversal point when the tool T is reciprocated with respect to the workpiece W from being mistakenly detected as the edge position of the workpiece W. When the tool T is not reciprocated with respect to the workpiece W, the speed command values ​​and the speed feedback values ​​can be used without processing.

[0058] Specifically, the data allocation processing section 34 detects, based on the point of change of the value obtained by subtracting the acceleration / deceleration change part from the chronological speed control data, a machining start position and a machining completion position as the edge position of the workpiece W, and thereby generates, as shown in Fig. 4 shows a first image W1 of the shape (outline) of the workpiece.

[0059] The data allocation processing section 34 also detects the edge position of the workpiece based on the spatial measurement data to a machined surface after machining the workpiece W, and thereby generates, as shown in Fig. 4, a second image W2 of the shape (outline) of the workpiece. For example, when the machined surface measuring device 20 is an optical sensor, the machined surface measurement data is image data. In this case, the data matching processing section 34 uses image processing technology to detect the edge position of the workpiece W from the image data and generate the second image W2 of the shape (outline) of the workpiece.

[0060] On the other hand, if the machined surface measuring device 20 is an optical microscope, a laser microscope, or a three-dimensional coordinate measuring machine, the machined surface measurement data is position data (coordinate data). In this case, the data matching processing section 34 detects the edge position of the workpiece W from the position data (coordinate data) and generates the second image W2 of the shape (outline) of the workpiece.

[0061] Then, the data association processing section 34 associates the chronological speed feedback values ​​with the spatial measurement data on a machined surface to the machined surface to superimpose the first image W1 of the shape of a workpiece and the second image W2 of the shape of a workpiece.

[0062] Subsequently, in step S14, the machined surface defect detection section 35 detects the defects (the streaks or striations) on the machined surface of the workpiece W and their positions based on the spatial machined surface measurement data stored in the storage section 33. Specifically, the machined surface measurement data is image data when the machined surface measuring device 20 is an optical sensor. In this case, the machined surface defect detection section 35 detects the defects on the machined surface and their positions based on the magnitude of the characteristic of the streaks and striations on the machined surface in the image data.

[0063] On the other hand, if the machined surface measuring device 20 is an optical microscope, a laser microscope, or a three-dimensional coordinate measuring machine, the machined surface measurement data is position data (coordinate data). In this case, the machined surface defect detection section 35 detects the defects on the machined surface and their positions based on a slight change (such as vibration) in the position data (coordinate data) of the machined surface.

[0064] Subsequently, the control data identification section 36 identifies error positions in step S15 as shown in Fig. 5, based on the speed control data (the first workpiece shape image W1) and the machined surface measurement data (the second workpiece shape image W2) assigned by the data assignment processing section 34, the speed control data to an error position D1 corresponding to the machined surface measurement data to an error position D2 detected by the machined surface error detection section 35.

[0065] Section 36 on the identification of control data on defect positions also assigns the direction of the defects (the streaks or stripes) of the machined surface to the direction of machining on the basis of the chronological control data of the defect positions.

[0066] Subsequently, the error distance detecting section 37 detects in step S16, as shown in the Fig. 6A and Fig. 6B, the distance d of the defects (the streaks or striations) on the machined surface of the workpiece W detected by the machined surface defect detecting section 35.

[0067] Subsequently, in step S17, the vibration frequency calculation section 38 determines the speed v in the machining direction based on the speed control data of the defect positions identified by the defect position control data identification section 36. Subsequently, based on the determined speed v and the distance d of the defects (the streaks or striations) detected by the defect distance detection section 37, the vibration frequency calculation section 38 calculates the frequency f of the vibrations of the machine tool 10 causing the defects using the following formula (1). f=v / d

[0068] Subsequently, in step S18, the adjustment section 39 adjusts the filter or machining condition of the numerical controller 17 to reduce the vibration based on the vibration frequency calculated by the vibration frequency calculation section 38. For example, the adjustment section 39 adjusts the cutoff frequency of the filter (e.g., a low-pass filter, a high-pass filter, or a band-pass filter) of the control circuit of the numerical controller 17 formed by the position command generation section, the speed command generation section, and the torque command generation section, thereby reducing the gain at the vibration frequency.

[0069] Alternatively, the setting section 39 sets a filter (for example, a notch filter or a band-stop filter) in the control circuit of the numerical control device 17. If the numerical control device 17 is implemented by software, the filter can be generated automatically, for example.

[0070] Alternatively, the setting section 39 sets the machining condition (speed, acceleration, or jerk) of the numerical controller 17 so that the machining speed is low. For example, the setting section 39 changes a parameter for determining the speed, acceleration, or jerk of the drive axes based on the set value of the machining program.

[0071] Here, the defects caused by vibrations (the streaks or striations) occur in the direction that intersects the machining direction. The defects caused by vibrations (the streaks or striations) can, for example, occur in the direction perpendicular to the machining direction, as in Fig. 7A, or they may occur in the direction that obliquely intersects the direction of machining, as shown in Fig. 7B. The defects caused by the vibrations (the streaks or bands) can appear linearly, as shown in the Fig. 7A and Fig. 7B, or they may appear in the form of curves, as in Fig. 7C shown.

[0072] Thus, based on the direction of the defects (the streaks or striations) of the machined surface and the machining direction assigned by the defect position identification section 36, the adjustment section 39 executes the above-described adjustment processing when the direction of the defects (the streaks or striations) of the machined surface intersects the machining direction. If the direction of the defects (the streaks or striations) of the machined surface is parallel to the machining direction, the defects are not caused by vibration, and therefore the adjustment section 39 does not execute the above-described adjustment processing.

[0073] As described above, in the numerical control system 100 of the machine tool according to the present embodiment, the machined surface error analysis device 30 associates the chronological speed control data during machining of the workpiece with the spatial measurement data of a machined surface of a workpiece after machining of the workpiece, and thereby identifies the speed control data of the error positions corresponding to the measurement data of a machined surface of a workpiece and the error positions of the machined surface of the workpiece W. Then, the machined surface error analysis device 30 calculates the frequency of vibrations based on the machining speed based on the identified speed control data of the error positions and the pitch of the errors (streaks or streaks).In this way, based on the pitch of the defects (the streaks or striations) on the machined surface of the workpiece and the machining speed when the defects occur, the frequency of the vibrations can be estimated, and the frequency of the vibrations of the machine tool 10 causing the defects on the machined surface of the workpiece can be accurately estimated even in machining in which the machining speed changes during machining of the workpiece.

[0074] In the numerical control system 100 of the machine tool according to the present embodiment, the machined surface error analysis device 30 adjusts the filter characteristic or the machining condition (speed, acceleration, or jerk) of the numerical control device 17 based on the calculated vibration frequency to reduce the vibration. Thus, it is possible to improve the quality of the machined surface at the time of subsequent machining passes.

[0075] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. The results described in connection with the present embodiment are simply those determined by listing the most preferable results achieved by the present invention, and therefore, the results of the present invention are not limited to those described in connection with the present embodiment.

[0076] In the above-described embodiment, the machined surface defect analysis device 30 data association processing section 34 for identifying the speed control data corresponding to the machined surface measurement data to the defect positions directly associates the speed control data from the numerical control device 17 itself and the machined surface measurement data from the machined surface measurement device 20 with each other, for example.However, the data matching processing section 34 may indirectly match the position control data from the numerical control device 17 and the machined surface measurement data, identify the position control data corresponding to the machined surface measurement data with the defect positions, and identify the speed control data corresponding to the position control data. In this case, the drive axis control data retrieval section 31 and the data matching processing section 34 of the machined surface defect analysis device 30 may be configured and operated as follows.

[0077] The drive axis control data retrieval section 31 retrieves the speed control data (the speed command values, the speed feedback values) and the position control data (the position command values, the position feedback values) as chronological drive axis control data in the machining of the workpiece W from the numerical control device 17 and stores them in the storage section 33 (according to Fig. 3 Step S11).

[0078] The data association processing section 34 associates the chronological position control data stored in the storage section 33 with the spatial measurement data of a machined surface (according to Fig. 3 (Step S13). Specifically, the data matching processing section 34 first converts the machined surface measurement data into machine coordinate data. For example, when the machined surface measuring device 20 is an optical sensor, the machined surface measurement data is image data. In this case, the data matching processing section 34 uses image processing technology to determine the coordinate data of the workpiece W from the image data. Then, the data matching processing section 34 converts the coordinate data of the workpiece W into the machine coordinate data based on a distance between the machined surface measuring device 20 and the workpiece W and the position (machine coordinates) and angle (view angle) of the machined surface measuring device 20.

[0079] On the other hand, if the machined surface measuring device 20 is an optical microscope, a laser microscope, or a three-dimensional coordinate measuring machine, the machined surface measurement data is position data (coordinate data). In this case, the data mapping processing section 34 converts the position data (coordinate data) of the workpiece W into machine coordinate data based on the distance between the machined surface measuring device 20 and the workpiece W, and the position (machine coordinates) and angle (view angle) of the machined surface measuring device 20.

[0080] Subsequently, the data allocation processing section 34 allocates the chronological position control data (the machine coordinates) during the machining of the workpiece W to the spatial position data (the machine coordinates) of the machined surface after the machining of the workpiece W. For example, as shown in Fig.4, the data allocation processing section 34 generates the first workpiece shape image W1 based on the chronological position control data (the machine coordinates) when machining the workpiece W. Similarly, the data allocation processing section 34 generates the second workpiece shape image W2 based on the spatial position data (the machine coordinates) of the machined surface after machining the workpiece W. Then, the data allocation processing section 34 associates the chronological position control data with the spatial position data of the machined surface to superimpose the first workpiece shape image W1 and the second workpiece shape image W2.

[0081] Here, the speed control data and the position control data are associated with each other in the numerical control device 17. In this way, the data association processing section 34 associates the chronological speed control data stored in the storage section 33 with the position control data to associate the chronological speed control data with the spatial position data of the machined surface.

[0082] In the above-described embodiment, the data association processing section 34 can indirectly associate torque control data from the numerical controller 17 and the machined surface measurement data, identify the torque control data corresponding to the machined surface measurement data at the error positions, and identify the speed control data corresponding to the torque control data. In this case, as in the case of the speed control data described above, the torque control data corresponding to the machined surface measurement data at the error positions can be identified based on the point of change of the torque control data.

[0083] Although the machined surface defect detection section 35 of the machined surface defect analysis device 30 in the above-described embodiment automatically detects the defects on the machined surface and their positions based on the image data or the position data (coordinate data) of the workpiece W (the machined surface) from the machined surface measurement device 20, they may be manually detected. For example, the measurement result (the three-dimensional image data or the position data) of the machined surface measurement device 20 may be displayed on a monitor or the like, the defects and their positions may be visually detected by a user, and the detected defect positions may be manually inputted to the machined surface defect analysis device 30.

[0084] Although the defect pitch detecting section 37 of the machined surface defect analysis device 30 automatically detects the pitch of defects (streaks or streaks) on the machined surface of the workpiece W in the above-described embodiment, it may be manually detected. For example, the measurement result (three-dimensional image data or position data) of the machined surface measurement device 20 may be displayed on a monitor or the like, the pitch of defects (streaks or streaks) may be visually detected by the user, and the detected pitch of defects (streaks or streaks) may be manually input to the machined surface defect analysis device 30. EXPLANATION OF REFERENCE SYMBOLS 2 heads 3 Holding element 4 Support column 5 stands 6 table 10 machine tools 11 to 15 coding device 16 measuring scale 17 numerical control device (control device) 20 Device for measuring a machined surface 30 Device for analyzing defects in a machined surface (analysis device) 31 Section for retrieving drive axle steering data (first retrieval section) 32 Section for retrieving measurement data for a machined surface (second retrieval section) 33 storage section 34 Processing section for data assignment 35 Section for recording defects of a machined surface 36 Section for identifying control data for error positions (identification section) 37 Section for recording the distance of defects 38 Section for calculating the frequency of vibrations (calculation section) 39 Setting section (setting section, determination section) 100 numerical control system (control system) CT1 to CT5 current detector M1 to M5 servo motors T tool W workpiece

Claims

[1] A control system (100) of a machine tool machining a workpiece (W), the control system (100) comprising: a control device (17) which controls a drive axis of the machine tool (10) based on speed control data; a machined surface measuring device (20) that measures a machined surface of the workpiece (W); and an analysis device (30) which analyses defects on the machined surface of the workpiece (W), wherein the analysis device (30) comprises: a first retrieving section (31) which retrieves the chronological speed control data when machining the workpiece (W) from the control device (17); a second retrieval section (32) that retrieves spatial measurement data on a machined surface measured by the machined surface measuring device (20) after machining the workpiece (W); a data association processing section (34) that associates the chronological speed control data retrieved by the first retrieval section (31) with the spatial measurement data relating to a machined surface retrieved by the second retrieval section (32); a machined surface error detection section (35) that detects the errors on the machined surface of the workpiece (W) and their positions based on the machined surface spatial measurement data retrieved by the second retrieving section (32); an identification section (36) which, based on the speed control data and machined surface measurement data assigned by the data assignment processing section (34), identifies the speed control data on the defect positions corresponding to the machined surface measurement data to the defect positions detected by the machined surface defect detection section (35); a defect pitch detecting section (37) that detects a pitch of the defects detected by the machined surface defect detecting section (35); and a calculation section (38) which determines a speed in a direction of machining based on the speed control data on the defect positions identified by the identification section (36), and calculates a frequency of vibrations of the machine tool (10) causing the defects based on the determined speed and the distance of the defects detected by the defect distance detection section (37). [2] The machine tool control system (100) according to claim 1, wherein the data allocation processing section (34): detecting a machining start position and a machining finish position as an edge position of the workpiece based on a change in the chronological speed control data to generate a first image of the shape of a workpiece; based on the spatial measurement data of a machined surface, detecting an edge position of the workpiece to generate a second image of the shape of a workpiece; and assigns the chronological speed control data to the spatial measurement data of a machined surface to superimpose the edge position of the first image of the shape of a workpiece and the edge position of the second image of the shape of a workpiece. [3] The machine tool control system (100) according to claim 1, wherein the data allocation processing section (34) comprises: detecting a machining start position and a machining completion position as an edge position of the workpiece based on a change in a value obtained by subtracting an acceleration / deceleration change part from the chronological speed control data to generate a first image of the shape of a workpiece; based on the spatial measurement data of a machined surface, detecting an edge position of the workpiece to generate a second image of the shape of a workpiece; and assigns the chronological speed control data to the spatial measurement data of a machined surface to superimpose the edge position of the first image of the shape of a workpiece and the edge position of the second image of the shape of a workpiece. [4] The control system (100) of the machine tool according to claim 1, wherein the first retrieval section (31) retrieves information on the position of the drive axis of the machine tool (10), which is chronological position control data associated with the chronological speed control data in machining the workpiece (W), from the control device (17), and the processing section (34) for assigning data: generates a first image of the shape of a workpiece based on the chronological position control data; creates a second image of the shape of a workpiece based on the spatial measurement data of a machined surface; assigns the chronological position control data to the spatial measurement data of a machined surface to superimpose the first image of the shape of a workpiece and the second image of the shape of a workpiece; and assigns the chronological speed control data to the chronological position control data in order to assign the chronological speed control data to the spatial measurement data for a machined surface. [5] The control system (100) of the machine tool according to claim 4, wherein the chronological position control data is machine coordinate information, and the spatial measurement data on a machined surface is machine coordinate information calculated based on machine coordinates of the machined surface measuring device (20). [6] The control system (100) of the machine tool according to any one of claims 1 to 5, wherein the analysis device (30) further comprises a setting section (39) that sets a filter or a machining condition of the control device (17) to reduce the vibrations based on the frequency of the vibrations calculated by the calculation section (38). [7] The control system (100) of the machine tool according to claim 6, wherein the setting section (39) sets a characteristic of the filter in a control circuit of the control device (17) or sets the filter in the control circuit of the control device (17). [8] The control system (100) of the machine tool according to claim 6, wherein the setting section (39) sets a parameter for determining a speed, an acceleration or a jerk of the drive axis in the control device (17) to set the machining condition. [9] The control system (100) of the machine tool according to any one of claims 1 to 8, wherein the defects on the machined surface of the workpiece are streaks or striations. [10] The control system (100) of the machine tool according to any one of claims 1 to 9, wherein the speed control data is a speed command value or a speed feedback value.

Images