CN111843829A - Apparatus for estimating surface roughness and method for estimating surface roughness - Google Patents

Apparatus for estimating surface roughness and method for estimating surface roughness Download PDF

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Publication number
CN111843829A
CN111843829A CN202010331404.4A CN202010331404A CN111843829A CN 111843829 A CN111843829 A CN 111843829A CN 202010331404 A CN202010331404 A CN 202010331404A CN 111843829 A CN111843829 A CN 111843829A
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workpiece
surface roughness
contact
measurement result
value
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Inventor
臂安彦
今枝大辅
岩井英树
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JTEKT Corp
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JTEKT Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
    • B24B49/02—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation according to the instantaneous size and required size of the workpiece acted upon, the measuring or gauging being continuous or intermittent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B5/00—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor
    • B24B5/36—Single-purpose machines or devices
    • B24B5/42—Single-purpose machines or devices for grinding crankshafts or crankpins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B51/00—Arrangements for automatic control of a series of individual steps in grinding a workpiece
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
    • G01B5/28—Measuring arrangements characterised by the use of mechanical techniques for measuring roughness or irregularity of surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q15/00—Automatic control or regulation of feed movement, cutting velocity or position of tool or work
    • B23Q15/007—Automatic control or regulation of feed movement, cutting velocity or position of tool or work while the tool acts upon the workpiece

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Grinding Of Cylindrical And Plane Surfaces (AREA)
  • A Measuring Device Byusing Mechanical Method (AREA)
  • Constituent Portions Of Griding Lathes, Driving, Sensing And Control (AREA)

Abstract

The invention provides a device for estimating surface roughness and a method for estimating surface roughness. The device for estimating surface roughness is provided with: a measurement result acquisition unit configured to acquire a measurement result when a contact of a sizing device capable of measuring a size of a workpiece is brought into contact with the workpiece and the sizing device is moved relative to the workpiece; a conversion unit configured to convert the measurement result obtained by the measurement result obtaining unit into at least one substitute value that is a substitute characteristic of the surface roughness of the workpiece; a model storage unit configured to store a model indicating a relationship between the at least one surrogate value and an actual measurement value of the surface roughness of the workpiece; and an estimating unit configured to estimate the surface roughness of the workpiece based on the model and the at least one surrogate value.

Description

Apparatus for estimating surface roughness and method for estimating surface roughness
Technical Field
The present invention relates to an apparatus for estimating surface roughness and a method of estimating surface roughness.
Background
Japanese patent application laid-open No. 2006-300823 discloses a surface roughness measuring apparatus that measures the surface shape of a workpiece by detecting the amount of displacement generated in a stylus supported by a cantilever when the stylus is moved in contact with the workpiece.
Measuring the surface roughness of a workpiece using the surface roughness measuring device described in japanese patent application laid-open No. 2006-300823 requires conveying the workpiece machined by a machine tool or the like to the surface roughness measuring device, and the time required for conveying the workpiece is periodically extended. Therefore, in order to shorten the realization cycle, it is desirable to grasp the surface roughness of the workpiece after machining in a machine tool used for machining the workpiece.
Disclosure of Invention
The present disclosure provides a surface roughness estimation device and a surface roughness estimation method that can grasp the surface roughness of a machined workpiece on a machine tool.
(1. surface roughness estimating apparatus)
According to an aspect of the present disclosure, a first device for estimating surface roughness includes: a measurement result acquisition unit configured to acquire a measurement result when a contactor of a sizing device is brought into contact with a workpiece and the sizing device is moved relative to the workpiece, wherein the sizing device is provided in a machine tool configured to machine the workpiece, has the contactor configured to be brought into contact with the workpiece, and is capable of measuring a dimension of the workpiece by detecting contact between the contactor and the workpiece; a conversion unit configured to convert the measurement result obtained by the measurement result obtaining unit into at least one substitute value that is a substitute characteristic of the surface roughness of the workpiece; a model storage unit configured to store a model indicating a relationship between the at least one surrogate value and an actual measurement value of the surface roughness of the workpiece; and an estimating unit configured to estimate the surface roughness of the workpiece based on the model and the at least one surrogate value.
According to the first surface roughness estimating device, the estimating unit estimates the surface roughness of the workpiece W based on the substitute value obtained by converting the measurement result obtained from the sizing device and the model indicating the relationship between the substitute value and the actual measurement value of the surface roughness of the workpiece. In this case, the first surface roughness estimating device can grasp the surface roughness of the machined workpiece on the machine tool. Accordingly, compared to a case where the machine tool measures the surface roughness of the workpiece using an external device provided outside the machine tool, the step of conveying the machined workpiece from the machine tool to the external device can be omitted, and therefore the cycle time can be shortened.
According to another aspect of the present disclosure, a second device for estimating surface roughness includes: a measurement result acquisition unit configured to acquire a measurement result when a contactor of a sizing device is brought into contact with a workpiece and the sizing device is moved relative to the workpiece, wherein the sizing device is provided in a machine tool configured to machine the workpiece, has a contactor configured to contact the workpiece, and is capable of measuring a dimension of the workpiece by detecting contact between the contactor and the workpiece; a conversion unit configured to convert the measurement result obtained by the measurement result obtaining unit into a substitute value that is a substitute characteristic of the surface roughness of the workpiece; and a model generation unit configured to generate a learning model configured to estimate the surface roughness of the workpiece by machine learning using the surrogate value and an actual measurement value of the surface roughness of the workpiece as learning data.
According to the second surface roughness estimating apparatus, the model generating unit generates a learning model for estimating the surface roughness of the workpiece by machine learning. Then, the second surface roughness estimating apparatus can improve the accuracy of estimating the surface roughness of the workpiece W by using the learning model. In addition, since the second surface roughness estimating device can estimate the surface roughness of the workpiece W based on the substitute value obtained by converting the measurement result obtained from the sizing device and the learning model, the machine tool can grasp the surface roughness of the machined workpiece on the machine tool equipment.
(2. surface roughness estimation method)
According to another aspect of the present disclosure, a method of estimating surface roughness includes: measuring a machined surface of a workpiece by bringing a contact of a sizing device into contact with the workpiece and moving the sizing device in parallel with respect to the workpiece, wherein the sizing device is provided in a machine tool that machines the workpiece, has the contact that contacts the workpiece, and is capable of measuring a dimension of the workpiece by detecting the contact of the contact with the workpiece; a conversion step of converting a measurement result obtained by the measurement into a substitute value that becomes a substitute characteristic for the surface roughness of the workpiece; and estimating the surface roughness of the workpiece based on a model representing a relationship between the substitute value and an actually measured value of the surface roughness of the workpiece.
According to this surface roughness estimating method, the same effects as those of the first surface roughness estimating apparatus described above are obtained.
Drawings
Fig. 1 is a top view of the grinding machine.
Fig. 2 is a diagram showing a configuration of the sizing device.
Fig. 3 is an example of a graph showing the measurement results for estimation.
Fig. 4 is a functional block diagram showing a configuration of a learning stage of the surface roughness estimating apparatus.
Fig. 5 is a functional block diagram showing a configuration of an estimation stage of the surface roughness estimating apparatus.
Fig. 6 is a graph showing an example of the regression model generated by the model generation unit.
Fig. 7 is a flowchart showing a surface roughness estimating process executed by the control device.
Fig. 8 is a flowchart showing a first example of the measurement step executed in the surface roughness estimation step.
Fig. 9 is a flowchart showing a second example of the measuring process performed in the surface roughness estimating process.
Detailed Description
(1. overview of surface roughness estimating apparatus)
The surface roughness estimating device estimates the surface roughness of a workpiece after machining in a machine tool device that machines the workpiece. The machine tool is provided with a sizing device, and the surface roughness estimating device measures the workpiece by the sizing device while relatively moving the sizing device with respect to the workpiece in a state where a contact of the sizing device is brought into contact with a machining surface of the workpiece after the machining of the workpiece by the machine tool. Then, the surface roughness estimating device estimates the surface roughness of the workpiece based on the measurement result obtained from the sizing device.
(2. constitution of grinding machine 1)
First, a configuration of a grinding machine 1 as an example of a machine tool will be described with reference to fig. 1. In the present embodiment, the grinding machine 1 is a grinder of a wheel slide traverse type. The machine tool may be a table-traversing type grinding machine, or may be a machine tool other than a grinding machine, for example, a lathe. In the present embodiment, the workpiece W is a crankshaft having a plurality of cylindrical surfaces with different outer diameters. The workpiece W is not limited to a crankshaft. That is, the workpiece W may be a rotating body other than the crankshaft, for example, a rotating body having the same outer diameter as the whole in the axial direction. The workpiece W is not limited to the rotating body.
As shown in fig. 1, the grinding machine 1 mainly includes a bed 10, a work support device 20, a tool support device 30, a tool moving device 40, a sizing device 50, a sizing device moving device 60, a wheel truing device 70, and a control device 80.
The bed 10 is fixed on an installation surface. The workpiece support device 20 rotatably supports the workpiece W. In the present embodiment, the workpiece support device 20 includes a headstock 21 and a tailstock 22. The headstock 21 is provided on the upper surface of the bed 10, and supports the workpiece W so as to be rotatable about the central axis (about the Z axis). The tailstock 22 is provided on the upper surface of the bed 10 at a position facing the headstock 21. The workpiece support device 20 rotatably supports the workpiece W at both ends thereof by a headstock 21 and a tailstock 22, and the workpiece W is rotated by driving a motor 23 provided in the headstock 21.
The tool supporting device 30 supports the tool in a rotatable manner. In the present embodiment, the tool supporting device 30 mainly includes a grinding wheel 31 as a tool and a grinding wheel holder 32. The grinding wheel 31 is a disk-shaped tool configured by fixing a plurality of abrasive grains with a binder. Abrasive particles there are general abrasive particles and superabrasive particles. As general abrasive grains, ceramic materials such as alumina and silicon carbide are widely known. The superabrasive particles are diamond or CBN. The grinding wheel holder 32 rotatably supports the grinding wheel 31. The wheel head 32 is provided with a motor 33 for applying a driving force for rotating the grinding wheel 31.
The tool moving device 40 relatively moves the grinding wheel 31 with respect to the bed 10. In the present embodiment, the tool moving device 40 mainly includes the first table 41 and the motor 42. The first table 41 is provided to be movable in the Z-axis direction with respect to the bed 10, and the motor 42 applies a driving force for moving the first table 41 in the Z-axis direction. A grinding wheel head 32 is provided on the upper surface of the first table 41, and the grinding wheel head 32 is provided movably in a direction (X-axis direction) toward and away from the workpiece W with respect to the first table 41. The tool moving device 40 is provided with a motor 43, and the motor 43 applies a driving force for moving the wheel head 32 in the X-axis direction with respect to the first table 41. In other words, the grinding machine 1 can move the grinding wheel 31 relative to the workpiece W in the X-axis direction and the Z-axis direction using the tool moving device 40.
The sizing device 50 mainly measures the outer diameter of the machining portion of the workpiece W. In addition, the sizing device 50 is also used to estimate the surface roughness of the machined surface of the workpiece W. The sizing device 50 is configured as described later. The sizing device moving device 60 mainly includes a second table 61 and a motor 62. The second table 61 is provided on the opposite side of the work support device 20 from the first table 41 so as to be movable in the Z-axis direction with respect to the bed 10. The motor 62 applies a driving force for moving the second table 61 in the Z-axis direction. A sizing device 50 is provided on the upper surface of the second table 61, and the sizing device 50 is movable relative to the second table 61 in the Z-axis direction. In other words, the grinding machine 1 can relatively move the sizing device 50 in the Z-axis direction with respect to the workpiece W using the sizing device moving device 60.
The grinding wheel truing device 70 trues the surface condition of the grinding wheel 31. The grinding wheel truing device 70 performs at least one of truing and dressing as the truing of the grinding wheel 31. The grinding wheel dresser 70 also has a function of measuring the size (diameter) of the grinding wheel 31.
Here, the dressing is a shape correcting operation, and is an operation of shaping the grinding wheel 31 in accordance with the shape of the workpiece W when the grinding wheel 31 is worn by grinding, an operation of removing the vibration of the grinding wheel 31 by partial wear, or the like. Dressing is a dresser (dressing) operation, and is an operation of adjusting the amount of protrusion of abrasive grains or creating a cutting edge of abrasive grains. Dressing is an operation of correcting scratches, clogging, falling, and the like, and is generally performed after shaping. In addition, shaping and trimming may not be performed separately.
The control device 80 controls each drive device based on the NC program and the control program of the PLC. The control device 80 controls the motors 23, 33, 42, 43, and 62 provided in the grinding machine 1 based on the NC program. The control program of the PLC operates the output device in response to ON/OFF of a command signal from the input device. For example, the controller 80 grinds the workpiece W based on the diameter of the workpiece W measured by the sizing device 50 until the workpiece W has a finished shape. When the grinding wheel 31 is replaced or corrected (trued or dressed), the control device 80 controls the motors 42 and 43, the grinding wheel dresser 70, and the like.
(3. construction of sizing device 50)
Next, the structure of the sizing device 50 will be described with reference to fig. 2. As shown in fig. 2, the sizing device 50 mainly includes a device main body 51, a pair of contacts 52a and 52b, a pair of hooks 53a and 53b, and a differential transformer 54. The contactors 52a, 52b are provided in contact with the outer peripheral surface of the workpiece W. Specifically, one of the pair of contacts 52a, 52b contacts the outer peripheral surface of the workpiece W from above, and the other contact 52b contacts the outer peripheral surface of the workpiece W from below. The hooks 53a, 53b hold the contacts 52a, 52b, and support the contacts 52a, 52b so as to be relatively displaceable with respect to the apparatus main body 51. Specifically, one hook 53a of the pair of hooks 53a, 53b supports one contact 52a, and the other hook 53b supports the other contact 52 b.
The differential transformer 54 is housed in the device body 51. The differential transformer 54 detects the displacement of the pair of hooks 53a, 53b that is displaced in accordance with the displacement of the pair of contacts 52a, 52b, and outputs an electrical signal corresponding to the displacement of the hooks 53a, 53 b. During grinding, the controller 80 determines the positions of the hooks 53a and 53b when the pair of contacts 52a and 52b contact the outer peripheral surface of the workpiece W based on the electric signal output from the differential transformer 54, and measures the outer diameter of the workpiece W based on the positions of the hooks 53a and 53 b. As will be described later, the surface roughness estimating apparatus 100 estimates the surface roughness of the machined surface of the workpiece W based on the electric signal output from the differential transformer 54.
(4. overview of surface roughness estimating apparatus 100)
Next, an outline of the surface roughness estimating apparatus 100 will be described. The surface roughness estimating apparatus 100 estimates the surface roughness of a workpiece W ground by a grinding machine 1, which is an example of a machine tool. The surface roughness estimating apparatus 100 may be an apparatus incorporated in the grinding machine 1, or may be a unit separate from the grinding machine 1.
Here, the correlation between the measurement result of the sizing device 50 and the surface roughness will be described. The grinding machine 1 uses the sizing device 50 when estimating the surface roughness by the surface roughness estimation device 100. Specifically, in the grinding machine 1, in a state where at least one of the contactors 52a and 52b is brought into contact with the machining surface of the workpiece W after machining, the measurement by the sizing device 50 is performed while moving the contactors 52a and 52b in the central axis direction (Z-axis direction) of the workpiece W with respect to the machining surface. Hereinafter, the measurement result measured by the sizing device 50 while the contacts 52a and 52b are brought into contact with each other and the contacts 52a and 52b are moved in the Z-axis direction is referred to as an "estimation measurement result".
Fig. 3 is a graph showing an example of the measurement result for estimation. In the graph shown in fig. 3, the horizontal axis represents the positions (moving distances) of the contacts 52a and 52b from the measurement start point, and the vertical axis represents the output values (e.g., voltage values) of the electric signals obtained from the sizing device 50 as the measurement results for estimation.
Specifically, fig. 3 shows three graphs (1) to (3) showing the measurement results for estimation obtained by measuring the machining surfaces of three workpieces W1 to W3 having different actual measurement values of surface roughness by the sizing device 50. Further, the measurement results for estimation of the workpiece W1 are shown in the graph (1), the measurement results for estimation of the workpiece W2 are shown in the graph (2), and the measurement results for estimation of the workpiece W3 are shown in the graph (3). In addition, among the three workpieces W1-W3, the measured value of the surface roughness of the workpiece W1 was the smallest, and the measured value of the surface roughness of the workpiece W3 was the largest.
As shown in fig. 3, graph (1) has the smallest amplitude among the three graphs (1) - (3), and graph (3) has the largest amplitude among the three graphs (1) - (3). In other words, the graph showing the measurement result for estimation of the workpiece W1 having the smallest actually measured value of the surface roughness has the smallest amplitude among the three graphs (1) to (3), and the graph showing the measurement result for estimation of the workpiece W3 having the largest actually measured value of the surface roughness has the largest amplitude among the three graphs (1) to (3).
In this way, a correlation is identified between the measurement results of the sizing device 50 and the measured values of the surface roughness. In view of this, the surface roughness estimating apparatus 100 estimates the surface roughness of the workpiece W after machining based on the measurement results for estimation. In the present embodiment, the case where the surface roughness estimating apparatus 100 estimates the surface roughness of the outer peripheral surface of the workpiece W is described as an example, but the surface roughness of the inner peripheral surface of the workpiece W may be estimated.
(5. constitution of surface roughness estimating apparatus 100)
Next, the configuration of the surface roughness estimating apparatus 100 will be described with reference to fig. 4 and 5. As shown in fig. 4, the surface roughness estimating apparatus 100 has the following configuration that functions as a learning stage. That is, the surface roughness estimating apparatus 100 includes a measurement result acquiring unit 110, a converting unit 120, an actual measurement value acquiring unit 130, a model generating unit 140, and a model storing unit 150.
The measurement result acquisition unit 110 acquires measurement results for estimation. Specifically, the grinding machine 1 brings the contact pieces 52a and 52b into contact with the machining surface of the workpiece W immediately after the grinding. In this state, the grinding machine 1 performs measurement by the sizing device 50 while moving the second table 61 in the Z-axis direction. Then, the measurement result acquisition unit 110 acquires the electric signal output from the differential transformer 54 as an estimation measurement result.
The conversion unit 120 converts the measurement result for estimation obtained by the measurement result obtaining unit 110 into a substitute value that is a substitute characteristic for the surface roughness of the workpiece W. The actual measurement value acquisition unit 130 acquires an actual measurement value of the surface roughness of the workpiece W measured by a surface roughness measurement device as an external device. The model generation unit 140 generates a model indicating the relationship between the surrogate value converted by the conversion unit 120 and the actual measurement value acquired by the actual measurement value acquisition unit 130. The model storage unit 150 stores the model generated by the model generation unit 140.
As shown in fig. 5, the surface roughness estimating apparatus 100 has the following configuration that functions as an estimation stage. That is, the surface roughness estimating apparatus 100 includes a measurement result acquiring unit 110, a converting unit 120, a model storing unit 150, an estimating unit 160, and a determining unit 170.
The estimating unit 160 estimates the surface roughness of the workpiece W based on the surrogate value of the measurement result for estimation newly acquired by the measurement result acquiring unit 110 converted by the converting unit 120 and the model stored in the model storage unit 150. The determination unit 170 performs determination based on the estimation result of the estimation unit 160. Specifically, the determination unit 170 includes a good/bad determination unit 171 and a correction timing determination unit 172.
The quality determination unit 171 determines whether or not the processed workpiece W is acceptable. For example, the quality determination unit 171 determines whether or not the estimated value of the surface roughness obtained as the estimation result by the estimation unit 160 is equal to or less than a first threshold value set in advance. As a result, if the estimated value of the surface roughness is equal to or less than the first threshold, the quality determination unit 171 determines that the workpiece W is acceptable.
In this way, the surface roughness estimating apparatus 100 can determine the quality of the workpiece W after machining based on the estimation result of the estimating unit 160. The grinding machine 1 can determine the quality of the workpiece W after machining on the grinding machine 1. As a result, compared to a case where an operator measures the surface roughness of the machined workpiece W using a surface roughness measuring device as an external device provided outside the grinding machine 1, the work of conveying the workpiece W from the grinding machine 1 to the surface roughness measuring device can be omitted, and accordingly, the cycle time can be shortened.
In addition, when the quality determination unit 171 determines that the workpiece W is defective, the operator can perform processing on the workpiece W (such as discarding or regrinding the workpiece) before performing subsequent processing on the workpiece W. In other words, since the subsequent processing of the defective workpiece W by the operator can be avoided, the work efficiency can be improved.
The dressing timing determination unit 172 determines whether or not the grinding wheel 31 is dressed. Here, in the present embodiment, the grinding machine 1 performs grinding processing by plunge grinding on the workpiece W. Therefore, it is considered that the estimated value of the surface roughness reflects the surface condition of the grinding wheel 31. Therefore, the correction timing determination unit 172 determines whether or not the estimated value of the surface roughness exceeds a preset second threshold value. As a result, when the estimated value of the surface roughness exceeds the second threshold value, the dressing timing determination unit 172 determines that it is the timing to dress the grinding wheel 31, and the control device 80 performs dressing or dressing of the grinding wheel 31.
When the estimated value of the surface roughness exceeds the second threshold value, it is determined as the timing to correct the grinding wheel 31. This makes it possible to suppress the occurrence of a failure due to the deterioration of the surface state of the grinding wheel 31 in the grinding machine 1. In this case, the grinding machine 1 can determine the correction timing of the grinding wheel 31 based on the estimated value of the surface roughness of the workpiece W, which is a standard for grasping the surface state of the grinding wheel 31. Thus, the grinding wheel 31 can be corrected at an optimum timing as compared with a case where the grinding machine 1 corrects the grinding wheel 31, for example, every predetermined number of times of grinding, and therefore, the tool life of the grinding wheel 31 can be extended while suppressing the occurrence of defective products. The surface roughness estimating apparatus 100 will be described below with reference to specific examples.
(5-1. surface roughness estimating apparatus 101 of the first example)
First, a first example of the surface roughness estimating apparatus 100 will be described. As shown in fig. 4, the surface roughness estimating apparatus 101 of the first example has the following configuration that functions as a learning stage. That is, the surface roughness estimating apparatus 101 of the first example includes the measurement result acquiring unit 110, the converting unit 121, the actual measurement value acquiring unit 130, the model generating unit 141, and the model storing unit 151.
The conversion unit 121 converts the measurement result of the sizing device 50 into a substitute value by using a conversion method stored in advance. The conversion method is based on arithmetic mean coarseness calculation. Specifically, the conversion unit 121 first extracts N values Z of the extracted data from the measurement result of the sizing device 501－Zn(e.g., voltage value). Next, the conversion section 121 calculates the values Z of the N extracted data1－ZnAverage value Z ofavgAnd calculating the value Z of each extracted dataiWith the average value ZavgThe absolute value of the difference. Then, the conversion unit 121 divides the total of the absolute values by the number (N) of extracted data to obtain a substitute value. In other words, the calculation formula used by the conversion section 121 is expressed by the following formula.
[ EQUATION 1 ]
Figure BDA0002465080250000091
The model generating unit 141 collects, for a plurality of workpieces W, the surrogate values obtained by converting the measurement results for estimation of the machined surfaces of the workpieces by the converting unit 121, and the actual measurement values of the surface roughness of the machined surfaces acquired by the actual measurement value acquiring unit 130. Then, the model generating unit 141 generates a regression model indicating the relationship between the surrogate value and the actual measurement value based on the collected surrogate value and actual measurement value. The regression model is a model for estimating the surface roughness of the workpiece, and the regression model generated by the model generation unit 141 is stored in the model storage unit 151.
As shown in fig. 5, the surface roughness estimating apparatus 101 of the first example has the following configuration that functions as an estimation stage. That is, the surface roughness estimating apparatus 101 of the first example includes the measurement result acquiring unit 110, the converting unit 121, the model storing unit 151, the estimating unit 161, and the determining unit 170. The estimating unit 161 estimates the surface roughness of the machined surface of the new workpiece W based on the surrogate value obtained by the converting unit 121 converting the measurement result for estimation newly acquired by the measurement result acquiring unit 110 and the regression model stored in the model storage unit 151.
Fig. 6 is a graph showing an example of a regression model showing a relationship between an actual measurement value and a surrogate value. As shown in fig. 6, a correlation is identified between the measured value and the surrogate value. In other words, a relationship is recognized in which the larger the surface roughness as an actual measurement value, the larger the value of the substitute value. Thus, the surface roughness estimating apparatus 100 can estimate the surface roughness of the workpiece based on the measurement result obtained from the sizing device 50 and the regression model stored in the model storage unit 151.
In this way, the grinding machine 1 can grasp the surface roughness of the workpiece after machining on the grinding machine 1 by using the surface roughness estimating device 101 of the first example. Thus, compared to the case where the grinding machine 1 measures the surface roughness of the workpiece W using an external device provided outside the grinding machine 1, the step of conveying the machined workpiece W from the grinding machine 1 to the external device can be omitted, and therefore the cycle time can be shortened. In addition, the surface roughness estimating apparatus 101 of the first example can improve the accuracy of estimating the surface roughness of the workpiece W by using the regression model generated by the model generating unit 141.
(5-2. surface roughness estimating apparatus 102 of the second example)
Next, a second example of the surface roughness estimating apparatus 100 will be described. As shown in fig. 4, the surface roughness estimating apparatus 102 of the second example has the following configuration that functions as a learning stage. That is, the surface roughness estimating device 102 of the second example includes the measurement result acquiring unit 110, the converting unit 122, the actual measurement value acquiring unit 130, the model generating unit 142, and the model storing unit 152.
The conversion unit 122 converts the measurement result for estimation into a plurality of substitute values by using a plurality of different conversion methods. The plurality of conversion methods are based on a calculation of a parameter of the surface roughness. Examples of the calculation formula used by the conversion unit 122 include the above-described calculation formula based on the arithmetic average roughness, and calculation formulas based on parameters such as the ten-point average roughness, the center average roughness, and the maximum height.
The model generation unit 142 generates a learning model for estimating the surface roughness of the workpiece W by machine learning using the plurality of substitute values converted by the conversion unit 121 and an actual measurement value of the surface roughness of the workpiece W measured by the surface roughness measurement device as learning data. Specifically, the model generation unit 142 collects, for a plurality of workpieces W, a plurality of substitute values obtained by converting the measurement result for estimation of the machined surface of the workpiece by the conversion unit 122, and an actual measurement value obtained by measuring the machined surface by the surface roughness measurement device. Then, the model generation unit 142 generates a learning model indicating the relationship between the plurality of surrogate values and the actual measurement value by machine learning based on the plurality of surrogate values and the actual measurement value of the collected lane, and the generated learning model is stored in the model storage unit 152.
As shown in fig. 5, the surface roughness estimating apparatus 102 of the second example has the following configuration that functions as an estimation stage. That is, the surface roughness estimating apparatus 102 of the second example includes the measurement result acquiring unit 110, the converting unit 122, the model storing unit 152, the estimating unit 162, and the determining unit 170. The estimation unit 162 estimates the surface roughness of the machined surface of the new workpiece W based on the plurality of surrogate values obtained by the conversion unit 122 converting the measurement result for estimation newly acquired by the measurement result acquisition unit 110 and the learning model stored in the model storage unit 152.
In this way, the grinding machine 1 can grasp the surface roughness of the workpiece after machining on the grinding machine 1 by using the surface roughness estimating apparatus 102 of the second example. Thus, compared to the case where the grinding machine 1 measures the surface roughness of the workpiece W using an external device provided outside the machine tool of the grinding machine 1, the step of conveying the machined workpiece W from the grinding machine 1 to the external device can be omitted, and therefore the cycle time can be shortened. In addition, the surface roughness estimating apparatus 102 of the second example generates a learning model for estimating the surface roughness of the workpiece W, and estimates the surface roughness of the workpiece W using the generated learning model, so that the accuracy of estimating the surface roughness of the workpiece W can be improved.
(6. surface roughness estimating step)
Next, a surface roughness estimating step, which is a procedure for estimating the surface roughness of the workpiece W using the sizing device 50, will be described with reference to a flowchart shown in fig. 7. In the present embodiment, a case where the grinding machine 1 performs grinding of the workpiece W by plunge grinding will be described as an example. Further, the grinding machine 1 can also perform grinding processing on the workpiece W by vertical feed grinding.
As a first step in the surface roughness estimating step, the grinding machine 1 measures the machined surface by the sizing device 50 (S1: measuring step). Specifically, the grinding machine 1 brings at least one of the contacts 52a and 52b into contact with the machined surface of the workpiece W on which the grinding process of the grinding wheel 31 has been completed. Then, the grinding machine 1 moves the sizing device 50 relative to the workpiece W in the central axis direction (Z-axis direction) of the workpiece W while bringing the contactors 52a, 52b into contact with the machining surface. At this time, the controller 80 moves the second table 61 in the Z-axis direction while bringing the contactors 52a and 52b into contact with the processing surface, and performs measurement by the sizing device 50. Then, the measurement result acquisition unit 110 acquires the electric signal output from the differential transformer 54 as a measurement result for estimation.
Next, the conversion unit 120 converts the estimation measurement result acquired by the measurement result acquisition unit 110 into a substitute value (S2: conversion process). Then, estimation unit 160 estimates the surface roughness of workpiece W based on the surrogate value converted by conversion unit 120 and the model stored in model storage unit 150 (S3: estimation process). Thereafter, the determination unit 170 determines whether or not the workpiece W is acceptable based on the estimation result of the estimation unit 160, and determines whether or not the workpiece W is in the grinding wheel 31 correction timing (S4: determination step).
(7. operation example of grinding machine 1 in measuring step (S1))
Here, an example of the operation of the grinding machine 1 in the measurement step (S1) will be described. In other words, the control device 80 performs the operation control of the grinding machine 1 in parallel with the grinding of the workpiece W by the grinding wheel 31 and the operation control of the grinding machine 1 in parallel with the estimation of the surface roughness of the workpiece W using the sizing device 50, thereby shortening the cycle time. Therefore, the operation control of the grinding machine 1 by the control device 80 in the measurement step (S1) will be described by way of example.
(7-1. first example of operation of grinding machine 1 in measuring step (S1))
First, a first example of the operation of the grinding machine 1 in the measurement step (S1) will be described with reference to the flowchart shown in fig. 8. As shown in fig. 7, in the measuring step of the first example, when the grinding wheel 31 finishes machining the workpiece W (S11), the grinding machine 1 starts a retracting operation of retracting the grinding wheel 31 from the workpiece W (S12). Specifically, after the spark is completed, for example, the controller 80 drives the motor 33 to retract the wheel head 32 from the work support device 20.
Next, the grinding machine 1 retracts the grinding wheel 31 from the workpiece W, and moves the sizing device 50 in the Z-axis direction with respect to the workpiece W while bringing the contactors 52a, 52b into contact with the workpiece W (S13). Specifically, the controller 80 drives the motor 62 to move the second table 61 in the Z-axis direction while at least one of the contactors 52a and 52b is in contact with the machined surface of the workpiece W that has been machined, and measures the machined surface by the sizing device 50.
In other words, the grinding machine 1 needs to move the wheel head 32 and the first table 41 during the plunge grinding from the end of grinding one machined surface of the workpiece W to the start of grinding the other machined surface to be machined next. In this regard, according to the measuring step of the first example, while the grinding wheel 31 is retreated from the workpiece W, the control device 80 moves the sizing device 50 in the Z-axis direction with respect to the workpiece W in a state where the contactors 52a and 52b are brought into contact with the machined surface of the machined workpiece W, and measures the machined surface by the sizing device 50. Thus, the grinding machine 1 can eliminate the need to set a waiting time for measuring the machining surface of the workpiece W by the sizing device 50 separately from the operation time of the grinding machine 1 during the plunge grinding, and thus the cycle can be shortened.
In this case, the grinding machine 1 can measure the workpiece W that continues to rotate after the grinding process by the sizing device 50. In other words, in this case, since the grinding machine 1 does not need to rotate the workpiece W again to perform the measurement by the sizing device 50 after the rotation of the workpiece W is stopped after the grinding process, the cycle time can be shortened and the power can be saved.
(7-2. second example of operation of grinding machine 1 in measuring step (S1))
First, a second example of the operation of the grinding machine 1 in the measurement step (S1) will be described with reference to the flowchart shown in fig. 9. As shown in fig. 9, in the measuring step of the second example, when the grinding wheel 31 finishes machining the workpiece W (S21), the controller 80 determines whether or not there is an unprocessed portion (S22). In other words, the control device 80 determines whether or not there is a portion where the grinding process is not completed.
As a result, if there is an unprocessed portion (YES in S22), the grinding machine 1 starts grinding the unprocessed portion (S23). Then, the grinding machine 1 moves the sizing device 50 relative to the workpiece W while bringing the contact pieces 52a and 52b into contact with the machined surface of the machined workpiece W while machining the workpiece W with the grindstone 31 (S24). Specifically, the control device 80 performs grinding by the grinding wheel 31 on the machined surface of the workpiece W whose machining has not been completed, and drives the motor 62 to move the second table 61 in the Z-axis direction while at least one of the contactors 52a and 52b is in contact with the machined surface of the workpiece W whose machining has been completed, and performs measurement of the machined surface by the sizing device 50.
In this way, according to the measuring process of the second example, the control device 80 simultaneously performs the grinding process by the grinding wheel 31 on the unprocessed portion and the measurement by the sizing device 50 on the processed portion. In this case, the grinding machine 1 does not need to set a waiting time for measuring the machining surface of the workpiece W by the sizing device 50 separately from the operation time of the grinding machine 1 during the plunge grinding, and therefore the cycle can be shortened. Further, since the grinding machine 1 can measure the rotating workpiece W by the sizing device 50, the cycle time can be shortened and power can be saved.
On the other hand, if there is no unprocessed portion (S22: NO), the grinding machine 1 performs the same processing as the grinding processing of the first example. In other words, in this case, the grinding machine 1 starts the retracting operation of retracting the grinding wheel 31 from the workpiece W (S25). Next, the grinding machine 1 retracts the grinding wheel 31 from the workpiece W, and moves the sizing device 50 in the Z-axis direction with respect to the workpiece W while bringing the contactors 52a, 52b into contact with the workpiece W (S26). This enables the grinding machine 1 to achieve a reduction in cycle time.
In the present embodiment, the workpiece W is a crankshaft having a plurality of cylindrical surfaces with different outer diameters. In this regard, the surface roughness estimating apparatus 100 can efficiently estimate the surface roughness of the workpiece W after machining by using the measuring process of the second example.
As described above, the grinding machine 1 can grasp the surface roughness of the workpiece W after machining on the machine tool by using the surface roughness estimating device 100, and therefore, the cycle time can be shortened. In particular, the surface roughness estimating apparatus 100 uses the sizing device 50, which is mainly used for measuring the size of the workpiece W during machining, for measuring the surface roughness of the machined surface of the workpiece W after machining. Thus, the surface roughness estimating apparatus 100 can eliminate the need to provide a new apparatus in the grinding machine 1. In addition, since the surface roughness estimating apparatus 100 uses the sizing device 50 used in grinding to estimate the surface roughness of the machined surface of the workpiece W after machining, the cycle time can be shortened.

Claims (15)

1. An apparatus for estimating surface roughness, comprising:
a measurement result acquisition unit configured to acquire a measurement result when a contactor of a sizing device is brought into contact with a workpiece and the sizing device is moved relative to the workpiece, wherein the sizing device is provided in a machine tool configured to machine the workpiece, has the contactor configured to contact the workpiece, and is capable of measuring a dimension of the workpiece by detecting contact between the contactor and the workpiece;
A conversion unit configured to convert the measurement result obtained by the measurement result obtaining unit into at least one substitute value that is a substitute characteristic of the surface roughness of the workpiece;
a model storage unit configured to store a model indicating a relationship between the at least one surrogate value and an actual measurement value of the surface roughness of the workpiece; and
an estimating unit configured to estimate the surface roughness of the workpiece based on the model and the at least one surrogate value.
2. The apparatus of claim 1, wherein,
the model is a regression model representing the relationship between the at least one representative value and the actual measurement value.
3. The apparatus of claim 1, wherein,
the conversion unit converts the measurement result into a plurality of substitute values having the at least one substitute value and different from each other by using a plurality of conversion methods different from each other,
the model is a learning model generated by machine learning that applies the plurality of substitute values and the actual measurement value as learning data.
4. The apparatus of claim 3, wherein,
the learning device further includes a model generation unit configured to generate the learning model by the machine learning using the plurality of substitute values and the actual measurement value as learning data.
5. The apparatus of any one of claims 1 to 4,
the conversion unit may be configured to determine, as the at least one substitute value among the substitute values, a value obtained by dividing a total of absolute values of an average value of the extracted data by the number of the extracted data, based on values of the extracted data extracted from the measurement result.
6. The apparatus of any one of claims 1 to 5,
the workpiece is a rotating body,
the measurement result acquiring unit acquires the measurement result when the contact is brought into contact with the outer peripheral surface of the workpiece or the inner peripheral surface of the workpiece and the sizing device is moved relative to the workpiece.
7. The apparatus of claim 6, wherein,
the workpiece is configured to rotate,
the measurement result acquiring unit acquires the measurement result when the contact is brought into contact with the rotating workpiece and the sizing device is moved relative to the workpiece.
8. The apparatus of any one of claims 1 to 7,
the machine tool includes:
a workpiece support device that rotatably supports the workpiece;
A tool support device configured to support a tool configured to process the workpiece;
a tool moving device for moving the tool supporting device relative to the workpiece supporting device; and
a control device configured to control at least one of the work support device, the tool moving device, and the sizing device,
the control device moves the positioning device relative to the workpiece while bringing the contact into contact with the workpiece after the workpiece is machined by the tool and while retracting the tool from the workpiece.
9. The apparatus of any one of claims 1 to 7,
the machine tool includes:
a workpiece support device that rotatably supports the workpiece;
a tool support device configured to support a tool configured to process the workpiece;
a tool moving device for moving the tool supporting device relative to the workpiece supporting device; and
a control device configured to control at least one of the work support device, the tool moving device, and the sizing device,
the control device is configured to move the sizing device relative to the workpiece while bringing the contact into contact with the machined surface of the machined workpiece while machining the workpiece with the tool.
10. The apparatus of claim 9, wherein,
the workpiece has a plurality of cylindrical surfaces having different outer diameters.
11. The apparatus of any one of claims 1 to 7,
the machine tool includes:
a workpiece support device that rotatably supports the workpiece;
a wheel head provided to be movable relative to the work support device; and
a grinding wheel rotatably supported by the wheel head and configured to grind the workpiece,
the measurement result acquiring unit acquires the measurement result when the contact is brought into contact with the machining surface of the workpiece ground by the plunge grinding and the sizing device is moved in the axial direction of the workpiece relative to the workpiece.
12. The apparatus of any one of claims 1 to 11,
the grinding wheel dresser further includes a dressing period determination unit configured to determine whether or not to dress the grinding wheel based on the at least one substitute value or the estimation result of the estimation unit.
13. The apparatus of any one of claims 1 to 12,
the workpiece quality determination device further includes a quality determination unit configured to determine the quality of the workpiece based on the at least one substitute value or the estimation result of the estimation unit.
14. An apparatus for estimating surface roughness, comprising:
a measurement result acquisition unit configured to acquire a measurement result when a contactor of a sizing device is brought into contact with a workpiece and the sizing device is moved relative to the workpiece, wherein the sizing device is provided in a machine tool configured to machine the workpiece, has the contactor configured to contact the workpiece, and is capable of measuring a dimension of the workpiece by detecting contact between the contactor and the workpiece;
a conversion unit configured to convert the measurement result obtained by the measurement result obtaining unit into a substitute value that is a substitute characteristic of the surface roughness of the workpiece; and
and a model generation unit configured to generate a learning model configured to estimate the surface roughness of the workpiece by machine learning using the surrogate value and an actual measurement value of the surface roughness of the workpiece as learning data.
15. A method of estimating surface roughness, comprising:
measuring a machined surface of a workpiece by bringing a contact of a sizing device into contact with the workpiece and moving the sizing device in parallel with respect to the workpiece, wherein the sizing device is provided in a machine tool that machines the workpiece, has the contact that contacts the workpiece, and is capable of measuring a dimension of the workpiece by detecting the contact of the contact with the workpiece;
A conversion step of converting a measurement result obtained by the measurement into a substitute value that becomes a substitute characteristic for the surface roughness of the workpiece; and
the surface roughness of the workpiece is estimated based on a model representing a relationship between the substitute value and an actual measurement value of the surface roughness of the workpiece.
CN202010331404.4A 2019-04-25 2020-04-24 Apparatus for estimating surface roughness and method for estimating surface roughness Pending CN111843829A (en)

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