JP2023157268A - Surface texture measurement device and surface texture detection system - Google Patents

Abstract

To provide a surface texture measurement device which can achieve improvement of accuracy of estimation of a surface texture.SOLUTION: A surface texture measurement device 20 measures a surface texture of a workpiece W ground by an abrasive wheel 12 by a grinder. The surface texture measurement device 20 includes: a contact member 22 configured to contact with a surface of the workpiece W and slide relative to the surface; a spring 27 which biases the contact member 22 to the surface of the workpiece W; a sensor 25 which detects at least one of an acceleration of vibration of the contact member 22 and displacement of vibration of the contact member 22 which are caused by sliding motion between the contact member 22 and the workpiece W; and a damping component application member 29 which applies a damping component to the contact member 22.SELECTED DRAWING: Figure 2

Description

The present invention relates to a surface texture measuring device and a surface texture detection system.

Conventionally, as a method for measuring the surface quality of a ground workpiece, Patent Document 1 discloses that an acceleration sensor is attached to a contact of a sizing device of a grinding machine, and sizing displacement data and acceleration sensor data are subjected to frequency analysis. A system for quickly measuring the surface properties of a workpiece in-process during grinding is disclosed.

JP 2021-79534 Publication

However, in the configuration disclosed in Patent Document 1, when the natural vibration characteristics of the contactor of the sizing device match the periodicity of chatter occurring on the surface of the workpiece, resonance occurs and the displacement data and acceleration sensor data Noise is generated that affects the measurement. As a result, there is a possibility that the measurement accuracy of the surface texture may be reduced, so there is room for improvement in improving the measurement accuracy.

The present invention has been made in view of this problem, and it is an object of the present invention to provide a surface texture measuring device that can improve the accuracy of estimating surface texture.

One aspect of the present invention is a surface texture measuring device that measures the surface texture of a workpiece ground by a grinding wheel in a grinding device,
a contact member configured to contact and relatively slide on the surface of the workpiece;
a spring that biases the contact member against the surface of the workpiece;
a sensor that detects at least one of the acceleration of the vibration of the contact member and the displacement of the vibration of the contact member caused by sliding between the contact member and the workpiece;
a damping component imparting member that imparts a damping component to the contact member;
A surface texture measuring device is provided.

According to the surface texture measuring device of the above aspect, a damping component is applied by the damping component applying member to the contact member that contacts and relatively slides on the surface of the workpiece. This changes the frequency characteristics of the contact member, so the natural vibration characteristics of the contact member and the periodicity of chatter generated on the surface of the workpiece do not match, thereby suppressing noise in the sensor detection results. can do. As a result, the measurement accuracy of surface texture can be improved.

As described above, according to the above aspect, it is possible to provide a surface texture measuring device that can improve the estimation accuracy of surface texture.

1 is a plan view showing the configuration of a surface texture detection system in Embodiment 1. FIG. 1 is a conceptual cross-sectional diagram of a surface texture measuring device in Embodiment 1. FIG. FIG. 2 is a conceptual cross-sectional diagram of a surface texture measuring device used in a vibration evaluation test in Embodiment 1. 5 is a diagram showing the results of a vibration evaluation test in Embodiment 1. FIG. 1 is a flowchart showing a grinding process of the grinding device in Embodiment 1. FIG. 3 is a diagram for explaining the surface properties of a workpiece in Embodiment 1. FIG. 3 is a diagram for explaining surface texture caused by a grindstone in Embodiment 1. FIG. 3 is a diagram for explaining surface texture caused by a grindstone in Embodiment 1. FIG. 3 is a diagram for explaining surface texture caused by relative vibration between centers in Embodiment 1. FIG. 1 is a block diagram showing the configuration of a surface texture detection system in Embodiment 1. FIG. 6 is a diagram for explaining measurement of first measurement data in Embodiment 1. FIG. 6 is a diagram for explaining measurement of second measurement data in Embodiment 1. FIG. FIG. 3 is a block diagram showing the configuration of a first data analysis processing section of the output device in Embodiment 1. FIG. FIG. 3 is a block diagram showing the configuration of a second data analysis processing section of the output device in Embodiment 1. FIG. FIG. 2 is a block diagram showing the configuration of an output processing section of the output device in Embodiment 1. FIG. FIG. 3 is a diagram for explaining the analysis result regarding the shape of a workpiece by the output processing unit in the first embodiment. FIG. 3 is a diagram for explaining an analysis result regarding a machine state by an output processing unit in the first embodiment. FIG. 3 is a diagram for explaining an analysis result (map) regarding machining quality by an output processing unit in the first embodiment. FIG. 3 is a diagram for explaining an analysis result (map) regarding machining quality by an output processing unit in the first embodiment. FIG. 3 is a diagram for explaining an analysis result (map) regarding machining quality by an output processing unit in the first embodiment. FIG. 3 is a diagram for explaining an analysis result (map) regarding machining quality by an output processing unit in the first embodiment. FIG. 3 is a diagram for explaining an analysis result (map) regarding machining quality by an output processing unit in the first embodiment. FIG. 3 is a conceptual cross-sectional diagram of a surface texture measuring device in modification 1;

(Embodiment 1)
Hereinafter, the surface texture detection system H and the surface texture measuring device 20 of the first embodiment will be described with reference to the drawings. As shown in FIG. 1, the surface texture detection system H includes a grinding device 10, a surface texture measuring device 20, an output device 30, and an image output device 40.

In the surface texture detection system H of the present embodiment, a surface texture measuring device 20 measures the surface (ground surface) of a workpiece W during or after being ground by the grinding device 10, and an output device 30 measures the surface (ground surface) of the workpiece W during or after being ground by the grinding device 10. Various data analysis processes are performed based on the measurement data measured by 20, and a plurality of analysis results related to the machining quality of the workpiece W are output. The image output device 40 of this embodiment outputs the plurality of analysis results output from the output device 30 as images.

Here, the measurement data detected by the surface texture measuring device 20 includes the acceleration of vibrations and the displacement (amplitude) of vibrations generated corresponding to the surface condition (surface texture) of the workpiece W. Note that the measurement data may include other data.

1. Configuration of the grinding device 10 As shown in FIGS. 1 and 2, the grinding device 10 includes a bed 11, a grinding wheel 12, a grinding wheel head 13, a headstock 14, a tailstock 15, a spindle table 16, and a control device 17. In addition, a surface texture measuring device 20 is also provided. The workpiece W rotates while being supported by a headstock 14 and a tailstock 15 at both ends in the rotation axis direction. The shape of the workpiece W is not limited and may be columnar or cylindrical, and the surface to be ground may be the outer circumferential surface or, if it is cylindrical, the inner circumferential surface thereof. In addition, in this Embodiment 1, the case where the workpiece W is cylindrical is illustrated. The grinding device 10 forms the shape of the workpiece W by bringing a grinding wheel 12 into contact with the surface (outer peripheral surface) of the rotating workpiece W and grinding the workpiece W.

The grinding wheel 12 is supported by a grinding wheel head 13 so as to be rotatable around an axis parallel to the Z-axis. A whetstone head guide part 11a is fixed on the bed 11, and the whetstone head 13 is supported by the whetstone head guide part 11a so as to be movable in the X-axis direction. A rotational driving force is applied to the grinding wheel 12 from a grinding wheel rotation motor 12a controlled by a control device 17, and the grinding wheel 12 rotates around a rotation axis. As the grindstone head 13 moves in the X-axis direction, the grinding wheel 12 approaches the workpiece W installed at a distance in the X-axis direction, and grinds the workpiece W.

On the bed 11, a spindle table guide part 11b is fixed at a position spaced apart from the grindstone head guide part 11a in the X-axis direction. The spindle table guide portion 11b supports the spindle table 16 so as to be movable in the Z-axis direction. On the spindle table 16, a spindle stock 14 and a tailstock 15 are arranged facing each other. The workpiece W is rotatably supported at both ends by a headstock 14 and a tailstock 15, and is rotated by a rotational driving force applied from a spindle rotation motor 14a controlled by a control device 17.

2. Configuration of Surface Texture Measuring Device 20 As shown in FIG. 2, the surface texture measuring device 20 includes a measurement feeler 22 as a contact member configured to come into contact with the surface of the workpiece W and slide relatively thereon. In the first embodiment, the measurement feeler 22 also functions as a contact of the sizing device 18 for detecting the diameter of the workpiece W. Therefore, in the first embodiment, the surface texture measuring device 20 is provided in the sizing device 18, and both are integrally configured. The surface texture measuring device 20 includes a housing 26 and a pair of measurement feelers 22 (22a, 22b), and the measurement feelers 22 have a probe 21 at the tip that contacts the surface of the workpiece W.

The measurement feeler 22 includes a shaft portion 221, and is rotatably supported on the shaft portion 221 by a support mechanism (not shown). Further, the measuring element 21 at the tip of the measuring feeler 22 is biased by a spring 27 so that the measuring element 21 is maintained in contact with the surface of the workpiece W. The spring 27 provides a spring constant k in the vibration component of the measurement feeler 22, and in the first embodiment, the spring 27 is a coil spring.

As shown in FIG. 2, the measuring element 21 is provided so as to come into contact with the surface of the workpiece W at two points sandwiching the rotation center O of the workpiece W. The pair of measurement feelers 22 are provided with a probe 21 at their distal ends, and are replaceable by detaching and attaching their base ends. As shown in FIG. 1, the surface texture measuring device 20 is supported by an axial movement device 23 and is movable in the axial direction of the workpiece W, that is, in the Z-axis direction. Movement of the surface texture measuring device 20 in the Z-axis direction is controlled by an axial movement control section 24 . Note that the movement in the Z-axis direction is not limited to using the axial movement device 23, and for example, it is also possible to use a shift function of the main shaft and tailstock shaft of the grinding device 10.

The surface texture measuring device 20 measures the irregularities on the outer periphery of the workpiece W as the surface condition of the workpiece W by converting the mechanical displacement of the measurement feeler 22 into an electric signal related to displacement and acceleration. In the first embodiment, the mechanical displacement of the measurement feeler 22 is converted into an electrical signal by a differential transformer 28 provided within the housing 26. As shown in FIG. 2, the differential transformer 28 is provided on the base end side of the measurement feeler 22 on the opposite side to the probe 21.
Here, the surface texture measuring device 20 measures the outer diameter of the workpiece W, that is, the surface condition of the workpiece W, in a frequency range of less than 60 Hz, for example. That is, the surface texture measuring device 20 can measure the low frequency component of the frequency characteristics of the surface condition of the workpiece W.

Furthermore, the surface texture measuring device 20 includes a sensor 25 assembled to at least one of the pair of measurement feelers 22 . The sensor 25 of the first embodiment is provided on a measurement feeler 22a located above in the direction of gravity. The sensor 25 of Embodiment 1 mainly has a function as an acceleration sensor added by being assembled to the measurement feeler 22 (22a), and has a function of, for example, 60 Hz or more among the frequency characteristics of the surface condition of the workpiece W. In the frequency domain, the acceleration associated with the displacement value in the surface state of the workpiece W is measured. That is, the sensor 25 detects the acceleration of the workpiece W due to the displacement (vibration) generated in the measurement feeler 22 when the measuring tip 21 moves relative to the workpiece W while being in contact with the surface of the workpiece W. It is measured as a high frequency component that is in a higher frequency region than a low frequency component of the frequency characteristics of the surface state.

Here, in this embodiment, a case is illustrated in which an acceleration sensor is used as the sensor 25 by being assembled (added) to the measurement feeler 22, but the sensor 25 is not limited to adding an acceleration sensor. For example, an analog output amplifier without a low-pass filter or a high-frequency digital output amplifier provided in the sizing device 18 can be used. In this case, since the surface texture measuring device 20 measures displacement rather than acceleration, the process of converting acceleration into displacement, which will be described later, becomes unnecessary.

As shown in FIG. 2, the surface texture measuring device 20 includes a damping component applying member 29 that applies a damping component c to the measurement feeler 22 as a contact member. In the first embodiment, the damping component imparting member 29 is made of a viscous member interposed between the measurement feeler 22 and the housing 26. The viscous member constituting the damping component imparting member 29 is made of a material having viscosity that generates a damping force against the vibration of the measurement feeler 22, and includes oil, grease, emulsion, rubber, elastomer, etc. can. Examples of the oil include chemically synthesized oil, mineral oil, animal oil, and vegetable oil. Examples of chemically synthesized oils include silicone-based oils, ester-based oils, ether-based oils, fluorine-based oils, and hydrocarbon-based oils. Further, the viscous member may be fluid (liquid, gas), solid, or semi-solid, and is preferably made of a chemically stable material that does not invade other components.

In the first embodiment, an example is shown in which the viscous member constituting the damping component imparting member 29 is made of silicone oil, which is a type of chemically synthesized oil, as the viscous fluid. In the first embodiment, the housing 26 has a sealed space 26a that includes the base end of the measuring feeler 22 on the opposite side from the measuring element 21, the shaft portion 221, the spring 27, and the differential transformer 28. Note that the housing 26 is provided with a through hole 261 through which the distal end side of the measurement feeler 22 protrudes, and a gap between the through hole 261 and the measurement feeler 22 is sealed with a deformable sealing material 262.

In the first embodiment, the sealed space 26a is filled with silicone oil as the damping component imparting member 29. The silicone oil used as the damping component imparting member 29 may contain dimethylpolysiloxane as a main component and have a viscosity within the range of 500 to 3000 mm ² /s. Note that the filling rate of silicone oil in the sealed space 26a is not limited, and can be 70% or more, 80% or more, or 90% or more of the sealed space 26a. Filling with silicone oil can be performed through an inlet (not shown) provided in the housing 26. Note that the injection port is sealed with a predetermined sealing material after being filled with silicone oil. Further, the differential transformer 28 is provided with a seal member (not shown) that prevents silicone oil from entering.

2-1. Vibration Evaluation Test of Surface Texture Measuring Device 20 The following vibration evaluation test was conducted on the surface texture measuring device 20 in the first embodiment. In the vibration evaluation test, as shown in FIG. The measuring element 21 of the feeler 22a was brought into contact with the piezo displacement monitor 102 to observe measurement data acquired by the sensor 25. As a test example, a sealed space 26a was filled with the above-mentioned silicone oil as the damping component imparting member 29, and as a comparative example, a sealed space 26a was not filled with silicone oil. The vibration amplitude (displacement) on the vibration stage was set to two types: 0.500 μm and 0.100 μm.

The test results of the vibration evaluation test are shown in FIGS. 4(a) and 4(b). As shown in FIGS. 4(a) and 4(b), in the high frequency band of 100 Hz to 1000 Hz, the gain of the measurement data shown on the vertical axis is 0.100 μm when the vibration amplitude (displacement) is 0.500 μm. In any case, in the comparative example without silicone oil, the peak value was a value far away from 1 in a plurality of frequency bands, and the gain width was large. This was particularly noticeable in the high frequency band A shown by the broken line, where the frequency was 400 to 1000 Hz. As a result, it was inferred that the measurement feeler 22a and the vibration stage 101 resonated in the high frequency band A showing the large peak value, and as a result, noise was generated.

On the other hand, in the test example with silicone oil, the gain value is close to 1 in almost the entire high frequency band from 100Hz to 1000Hz, and the gain width is also small, especially in the high frequency band. There was a significant difference in A from the comparative example. As a result, it can be inferred that the damping component c is imparted by the damping component imparting member 29 to the vibration of the measurement feeler 22a, thereby suppressing the resonance and reducing noise.

3. Grinding process of the workpiece W by the grinding device 10 The grinding device 10 grinds the workpiece W through a plurality of steps shown in FIG. The grinding process is divided according to the difference in grindstone feeding speed, and is performed in the order of rough grinding process St1, fine grinding process St2, fine grinding process St3, and spark-out process St4. The grinding wheel feeding speed of each process is as follows: coarse grinding process St1>fine grinding process St2>fine grinding process St3>spark out process St4. In the rough grinding step St1, the rough shape of the workpiece W is formed. In the subsequent fine polishing step St2 and fine polishing step St3, the surface shape of the workpiece W is adjusted while reducing the grindstone feed rate. In the final spark-out step St4, the surface of the workpiece W is finished, and the workpiece W is completed.

Here, in the surface texture detection system H, the surface texture measuring device 20 is used between the rough grinding step St1 during grinding of the workpiece W to the spark-out step St4, or after the spark-out step St4 when grinding is completed. It is preferable to measure the surface condition of the workpiece W. Note that the on-machine measurement system H outputs multiple analysis results related to machining quality, which will be described later, during in-process, but in-process refers to the period until the workpiece W is removed from the grinding device 10. This also includes after the spark-out step St4.

4. Overview of Output Device 30 Next, an overview of the output device 30 will be described. As shown in FIG. 6, the surface texture S, which is one of the machining qualities of the workpiece W ground by the grinding device 10, is determined due to various factors. That is, the surface texture S of the workpiece W includes a surface texture S1 caused by the grinding wheel to which the surface condition of the grinding surface of the grinding wheel 12 is transferred, as shown by the solid line and the dashed-double line in FIG. As shown by the broken line, the surface texture S2 due to the center-to-center relative vibration is transferred to the vibration generated by the relative change between the grinding wheel 12 and the workpiece W, that is, between the centers.

Then, the surface texture S, that is, the surface texture S1 and the surface texture S2 are measured as measurement data by the surface texture measuring device 20. Here, the measurement data measured by the surface texture measuring device 20 includes a low frequency component measured by the differential transformer 28 via the measurement feeler 22 and a high frequency component measured by the sensor 25. Therefore, it can be said that the surface texture S is determined by combining the low frequency component and the high frequency component.

The surface texture S1 caused by the grinding wheel is the surface texture in the circumferential direction and the axial direction of the workpiece W, and as shown in FIGS. The static workpiece reference radius surface texture S12 including the components is synthesized. Here, the surface texture S11 includes, for example, chatter vibration (hereinafter referred to as "chatter degree") which is unevenness caused by a grinding wheel in the circumferential direction of one cross section of the workpiece W, or chatter in the axial direction of the workpiece W. It reflects the processing accuracy such as the degree of variation in scale (hereinafter referred to as "scalability").

Further, the surface texture S2 due to center-to-center relative vibration is a surface texture in the circumferential direction of one cross section of the workpiece W, and as shown in FIG. 9, a low frequency component and a high frequency component are synthesized. That is, the surface texture S2 is a combination of the surface texture S21, which is a high frequency component, and the surface texture S22, which is a low frequency component. Here, the surface texture S2 includes, for example, the shape of the workpiece W that depends on the machining accuracy such as roundness, runout amount of the grinding surface, coaxiality, vibration of the grinding device 10, and self-excited vibration during machining. , mechanical conditions such as spark-out effects, and machining conditions.

Therefore, the output device 30 of this embodiment extracts a low frequency component and a high frequency component from the measurement data measured by the surface texture measuring device 20. Then, the output device 30 performs various data analysis processes on the extracted (obtained) low frequency components and high frequency components, and outputs a plurality of analysis results using the various data analysis processes.

4-1. Configuration of Output Device 30 As shown in FIG. 10, the output device 30 includes a basic data acquisition section 31, a first data analysis processing section 32, a second data analysis processing section 33, and an output processing section 34. .

4-2. Basic data acquisition unit 31
The basic data acquisition unit 31 acquires measurement data (displacement and acceleration) detected by the surface texture measuring device 20 during or after grinding. Specifically, as shown in FIG. 10, the basic data acquisition unit 31 acquires the first measurement data K1 outputted from the surface texture measuring device 20 as the first basic data D1, and also acquires the second measurement data K2 as the first basic data D1. 2. Obtained as basic data D2.

Here, as shown in FIG. 11, the surface texture measuring device 20 first sets measurement positions for measuring displacement and acceleration according to the surface condition of the workpiece W in the circumferential direction and the axial direction with respect to the workpiece W. The first measurement data K1 obtained by relatively spiral movement is detected and output to the basic data acquisition section 31. That is, when acquiring the first basic data D1, the measuring element 21 of the surface texture measuring device 20 is brought into contact with the surface of the workpiece W while the workpiece W is being rotated, and the surface texture is measured by the axial movement device 23. The measuring device 20 is continuously moved in the axial direction of the workpiece W. Here, the measurement position in this embodiment is a position where the probe 21 of the surface texture measuring device 20 contacts the surface of the workpiece W. Further, the first measurement data K1 includes measurement data of a low frequency component (displacement) measured by the differential transformer 28 and measurement data of a high frequency component (acceleration) measured by the sensor 25.

In addition, as shown in FIG. 12, the surface texture measuring device 20 can move the measurement positions at the same position in the axial direction (same position in the axial direction) or spaced apart in the axial direction without moving the measurement position in a spiral pattern. Second measurement data K2 for one circumference of the outer peripheral surface of the workpiece W when the workpiece W is moved is detected and output to the basic data acquisition section 31. That is, with the workpiece W being rotated, the probe 21 of the surface texture measuring device 20 is brought into contact with the surface of the workpiece W, and the axial direction moving device 23 moves the surface texture measuring device 20 in the axial direction of the workpiece W. Stop at the same position. Here, the second measurement data K2 includes measurement data of a low frequency component (displacement) and measurement data of a high frequency component (acceleration) measured by the sensor 25.

The basic data acquisition unit 31 acquires the spirally detected first measurement data K1 as the first basic data D1. The basic data acquisition unit 31 also acquires second measurement data K2 for one revolution acquired at the same position in the axial direction as second basic data D2. Then, the basic data acquisition section 31 outputs the first basic data D1 and the second basic data D2 to the first data analysis processing section 32 and the second data analysis processing section 33, respectively.

Here, the first basic data D1 and the second basic data D2 are time series data regarding displacement and acceleration. Note that the first basic data D1 and the second basic data D2 are generally acquired as data based on the time axis, but the rotation angle of the workpiece W can be calculated from the time and the rotational speed of the workpiece W. It may also be converted into reference data.

4-3. First data analysis processing section 32
The first data analysis processing unit 32 extracts low frequency components from the frequency characteristics of the first basic data D1 and the second basic data D2, and performs various data analysis processes described below on the extracted low frequency components. Calculate multiple first analysis results. Therefore, as shown in FIG. 13, the first data analysis processing section 32 includes a gain compensation section 320, a low frequency component extraction section 321, a spiral low frequency waveform generation section 322, a low frequency intercenter relative vibration waveform generation section 323, It mainly includes a workpiece reference radius calculation section 324.

The gain compensation unit 320 performs gain compensation on the first basic data D1 and the second basic data D2 acquired from the basic data acquisition unit 31. The displacement data signal detected by the differential transformer 28 as a displacement sensor tends to have a signal strength attenuated when it exceeds a specific frequency. Therefore, in order to keep the output level constant, the gain compensator 320 compensates the signal strength of the first basic data D1 and the second basic data D2 for each frequency based on the relationship between the frequency and the signal strength that is stored in advance. .

The low frequency component extraction unit 321 performs fast Fourier transform (hereinafter referred to as "FFT") on the first basic data D1 after gain compensation, and extracts the low frequency component D11 from the frequency characteristics of the first basic data D1. Extract. Furthermore, the low frequency component extraction unit 321 performs FTT on the second basic data D2 after gain compensation, and extracts the low frequency component D21, which is the first analysis result, from the frequency characteristics of the second basic data D2. Here, the low frequency component extraction unit 321 extracts, for example, low frequency components of the first basic data D1 and the second basic data D2 in a frequency range of less than 60 Hz (approximately 15 to 50 peaks as a waveform). Extract.

The spiral low frequency waveform generation unit 322 performs inverse fast Fourier transform (hereinafter referred to as “inverse FFT”) on the low frequency component D11 of the first basic data D1 extracted by the low frequency component extraction unit 321. Here, the first basic data D1 is first measurement data K1 (displacement) detected spirally along the outer peripheral surface (surface) of the workpiece W by the surface texture measuring device 20. Thereby, the spiral low frequency waveform generation unit 322 calculates a spiral low frequency waveform SLW representing the waveform of the displacement fluctuation in the spiral direction of the workpiece W, that is, the waveform of the low frequency component D11 of vibration, as the first analysis result.

The low frequency center-to-center relative vibration waveform generation section 323 performs inverse FFT on the low frequency component D21 of the second basic data D2 extracted by the low frequency component extraction section 321. Here, the second basic data D2 is second measurement data K2 (displacement) detected at the same position in the axial direction of the workpiece W by the surface texture measuring device 20. As a result, when inverse FFT is performed on the low frequency component D21 of the second basic data D2, a one-section low frequency waveform representing the displacement fluctuation in the circumferential direction (one round) of the workpiece W, that is, the low frequency component D21 of vibration is obtained. .

By the way, the one-section low frequency waveform is based on, for example, the relative position between the grinding wheel 12 and the workpiece W that does not change significantly during grinding of one workpiece W, such as the pump pulsation in the grinding device 10 or the setting accuracy of the workpiece W. It represents the relative vibration (low-frequency center-to-center relative vibration) that occurs due to a change in the center-to-center distance, and can be considered to be the same along the axial direction of the workpiece W for one workpiece W. Therefore, the low-frequency center-to-center relative vibration waveform generation unit 323 calculates the one-section low-frequency waveform obtained by performing the inverse FFT as the low-frequency center-to-center relative vibration waveform LDV, which is the first analysis result.

The workpiece reference radius calculation unit 324 calculates the spiral low frequency waveform SLW generated by the spiral low frequency waveform generation unit 322 and the low frequency center-to-center relative vibration waveform LDV generated by the low-frequency center-to-center relative vibration waveform generation unit 323. , is used to calculate the workpiece reference radius R resulting from the transfer of the surface condition of the grinding surface of the grinding wheel 12 on the surface of the ground workpiece W. Specifically, the workpiece reference radius calculation unit 324 calculates the workpiece reference radius R as the first analysis result by subtracting the low frequency center-to-center relative vibration waveform LDV from the spiral low frequency waveform SLW.

Here, the low-frequency center-to-center relative vibration waveform LDV is a one-section low-frequency waveform that is assumed to be the same in the axial direction of the workpiece W, as described above. Therefore, the workpiece reference radius calculation unit 324 adds (copies) the low frequency center-to-center relative vibration waveform LDV by the number corresponding to the number of spirals C of the spiral low frequency waveform SLW according to the following formula 1, and adds (copies) the low frequency center-to-center relative vibration waveform LDV to The workpiece reference radius R is calculated by subtracting from the waveform SLW.
R=SLW-C×LDV...Formula 1

4-4. Second data analysis processing section 33
The second data analysis processing unit 33 extracts high frequency components from the frequency characteristics of the first basic data D1 and the second basic data D2, and performs various data processing described below on the extracted high frequency components, thereby generating a plurality of 2. Calculate the analysis results. Therefore, as shown in FIG. 14, the second data analysis processing section 33 includes a gain compensation section 330, a spiral high frequency component extraction section 331, a one-section high frequency component extraction section 332, a spiral high frequency waveform generation section 333, a high frequency center-to-center relative It mainly includes a vibration waveform generation section 334 and a grindstone surface unevenness calculation section 335.

The gain compensation unit 330 performs gain compensation on the first basic data D1 and the second basic data D2 similarly to the gain compensation unit 320 described above.

The spiral high frequency component extraction unit 331 performs FFT on the first basic data D1 after gain compensation, and further converts the acceleration data into displacement data, thereby converting the high frequency component of the frequency characteristics of the first basic data D1 into a spiral high frequency. Extracted as component D12. Here, the first basic data D1 is first measurement data K1 (acceleration) detected spirally along the outer peripheral surface of the workpiece W by the surface texture measuring device 20. Further, the spiral high-frequency component extraction unit 331 extracts the frequency characteristics of a frequency range of 60 Hz or higher and lower than the detection upper limit frequency of the surface texture measuring device 20 (approximately 50 to 500 peaks as a waveform) as a high-frequency component. Extract as D12.

The 1-section high frequency component extraction unit 332 performs FFT on the second basic data D2 after gain compensation, and further converts the acceleration data into displacement data, thereby extracting the high frequency component D22 from the frequency characteristics of the second basic data D2. Extract. Further, the single-section high-frequency component extraction unit 332 extracts a high-frequency component excluding the grindstone rotation frequency component fg corresponding to the rotation speed of the grinding wheel 12 and its harmonics from the extracted high-frequency component D22 as a single-section high-frequency component D221. .

Here, the second basic data D2 is second measurement data K2 (acceleration) detected at the same position in the axial direction of the workpiece W by the sensor 25 of the surface texture measuring device 20. Thereby, the high frequency component extracted from the second basic data D2 corresponds to one round in the circumferential direction of the workpiece W, that is, one cross section of the workpiece W. Further, the single-section high-frequency component extracting unit 332 also extracts, as a high-frequency component, a frequency range of, for example, 60 Hz or more and below the upper limit of detection by the surface texture measuring device 20 (approximately 50 to 500 peaks in the waveform) as the high-frequency component D22. do.

The spiral high-frequency waveform generation section 333 performs inverse FFT on the spiral high-frequency component D12 of the first basic data D1 extracted by the spiral high-frequency component extraction section 331. Thereby, the spiral high-frequency waveform generation unit 333 calculates a spiral high-frequency waveform SHW representing the waveform of the spiral high-frequency component D12 of the displacement fluctuation in the spiral direction of the workpiece W, that is, the vibration, as the second analysis result.

The high-frequency center-to-center relative vibration waveform generation section 334 performs inverse FFT on the one-section high-frequency component D221 of the second basic data D2 extracted by the one-section high-frequency component extraction section 332. As a result, when inverse FFT is performed on the one-section high frequency component D221 obtained by excluding the grindstone rotation frequency component fg and its harmonics from the high frequency component of the second basic data D2, displacement fluctuation in the circumferential direction (one round) of the workpiece W, that is, A single-section high-frequency waveform representing a single-section high-frequency component D221 of vibration is obtained.

By the way, the one-section high frequency component D221 does not include the grindstone rotation frequency component fg corresponding to the rotation speed of the grindstone wheel 12 and its harmonics. Therefore, the one-section high-frequency waveform includes the surface texture S of the workpiece W (more specifically, the surface texture S2 caused by the relative vibration between centers) other than the grinding wheel rotation frequency component fg corresponding to the rotation speed of the grinding wheel 12 and its harmonics. represents the vibration that affects the surface texture S22). Here, examples of vibrations that affect the surface quality S22 of the workpiece W include rotation of a servo motor that controls the movement of the grindstone head 13 and spindle table 16, vibrations applied from the outside, and self-excited chatter. I can do it.

Therefore, the one-section high-frequency waveform represents the relative vibration (high-frequency center-to-center relative vibration) that occurs due to a change in the relative position of the grinding wheel 12 and the workpiece W, that is, the center-to-center distance, in the high-frequency region. Similar to the frequency waveform, it can be considered that one workpiece W is the same along the axial direction of the workpiece W. Therefore, the high-frequency center-to-center relative vibration waveform generation unit 334 calculates the one-section high-frequency waveform obtained by performing the inverse FFT as the high-frequency center-to-center relative vibration waveform HDV, which is the second analysis result.

The grindstone surface unevenness calculation unit 335 uses the spiral high-frequency waveform SHW generated by the spiral high-frequency waveform generation unit 333 and the high-frequency center-to-center relative vibration waveform HDV generated by the high-frequency center-to-center relative vibration waveform generation unit 334, Grinding wheel surface irregularities P resulting from the transfer of the surface condition of the grinding surface of the grinding wheel 12 on the outer peripheral surface of the ground workpiece W are calculated. Specifically, the grindstone surface unevenness calculation unit 335 calculates the grindstone surface unevenness P as the second analysis result by subtracting the high frequency inter-center relative vibration waveform HDV from the spiral high frequency waveform SHW.

Here, the high-frequency center-to-center relative vibration waveform HDV is a single-section high-frequency waveform that is assumed to be the same in the axial direction of the workpiece W, as described above. Therefore, the grindstone surface unevenness calculation unit 335 adds (copies) the high-frequency center-to-center relative vibration waveform HDV by a number that matches the number of spirals C of the spiral high-frequency waveform SHW, and subtracts it from the spiral high-frequency waveform SHW. By doing so, the grindstone surface unevenness P is calculated.
P=SHW-C×HDV...Formula 2

4-5. Output processing section 34
The output processing section 34 uses the plurality of first calculation results calculated by the first data analysis processing section 32 and the plurality of second calculation results calculated by the second data analysis processing section 33 to generate a plurality of analysis results. It is possible to process and output. Hereinafter, a plurality of output analysis results will be illustrated and explained.

The plurality of analysis results output by the output processing unit 34 are related to the machining quality of the workpiece W ground by the grinding device 10. Examples of machining quality include the shape (machining accuracy) of the workpiece W, such as the roundness of the workpiece W related to the above-mentioned surface texture S2, the amount of runout of the ground surface, and the coaxiality of the workpiece W. I can do it. Further, in relation to processing quality, the processing state of the grinding device 10 and the mechanical state of the grinding device 10 can be mentioned. The machining state is included in machining accuracy, and may include a spark-out state and a sharpness state of the grinding wheel 12. The mechanical state can include vibrations (mechanical vibrations) of the grinding device 10.

Regarding these machining quality, machining state, and machine state, the surface texture measuring device 20 uses second measurement data K2 (second basic data D2) measured at the same position in the axial direction while grinding the workpiece W. These are the analysis results obtained using . Therefore, these analysis results are output for each process in which the grinding device 10 grinds the workpiece W, that is, for all the workpieces W.

Furthermore, examples of machining quality include the surface texture S (surface texture S1) of the workpiece W, line roughness, etc., which are included in the machining accuracy. Regarding these machining quality (machining accuracy), after the workpiece W is ground, the surface texture measuring device 20 uses first measurement data K1 (first measurement data) measured in the circumferential direction and the axial direction of the workpiece W. This is an analysis result obtained using basic data D1) and second measurement data K2 (second basic data D2) measured at the same position in the axial direction. Therefore, these analysis results are output as appropriate, for example, after grinding the workpiece W.

As shown in FIG. 15, the output processing unit 34 of this embodiment includes a shape analysis output unit 341 that outputs analysis results related to machining quality, a machining status output unit 342 that outputs analysis results related to machining conditions, and a machining status output unit 342 that outputs analysis results related to machining conditions. It includes a machine state output section 343 that outputs analysis results related to the state, and a map generation output section 344 that outputs analysis results related to machining quality.

Here, the shape analysis output section 341, the machining state output section 342, and the machine state output section 343 output second measurement data K2 (second measurement data) measured by the surface texture measuring device 20 at the same position in the axial direction of the workpiece. The low frequency component and high frequency component of the basic data D2) are used. On the other hand, the map generation output unit 344 outputs low frequency components and high frequency components of the first measurement data K1 (first basic data D1) measured in the circumferential direction and axial direction of the workpiece W by the surface texture measuring device 20, and the workpiece. The low frequency component and the high frequency component of the second measurement data K2 (second basic data D2) measured at the same position in the axial direction are used.

The shape analysis output unit 341 acquires the low frequency inter-center relative vibration waveform LDV that is the first analysis result from the first data analysis processing unit 32 (low-frequency inter-center relative vibration waveform generation unit 323), and also performs the second data analysis. A high-frequency inter-center relative vibration waveform HDV, which is a second analysis result, is obtained from the processing unit 33 (high-frequency inter-center relative vibration waveform generation unit 334). Then, the shape analysis output unit 341 synthesizes (adds) the low-frequency center-to-center relative vibration waveform LDV and the high-frequency center-to-center relative vibration waveform HDV, thereby generating a Output the roundness and runout amount of the ground surface as analysis result A1. Note that, for example, when a plurality of roundnesses and runout amounts are analyzed in the axial direction of the workpiece W, the coaxiality of the workpiece W can also be output.

In order to evaluate the grinding effect of each of the grinding steps shown in FIG. Output as . For this reason, the machining state output unit 342 acquires the high frequency component D22 of the second basic data D2 as a second analysis result from the second data analysis processing unit 33 (one cross section high frequency component extraction unit 332) for each grinding process. do.

For example, when evaluating the grinding effect of the spark-out process St4, the machining state output unit 342 outputs the ratio ( fg2/fg1) is output as analysis result A2. In this case, it is evaluated that the closer the output analysis result A2 (fg2/fg1) is to "0", the higher the grinding effect of the spark-out process St4, and the closer it is to "1", the lower the grinding effect of the spark-out process St4. I can do it.

The machine state output section 343 acquires the low frequency component D21 of the second basic data D2 as the first analysis result from the first data analysis processing section 32 (low frequency component extraction section 321), and acquires the low frequency component D21 of the second basic data D2 from the first data analysis processing section 32 (low frequency component extraction section 321). The high frequency component D22 of the second basic data D2 is obtained from the one-section high frequency component extraction unit 332) as the second analysis result. Then, the mechanical state output unit 343 outputs the relationship between the frequency change and the amplitude as an analysis result A3, as shown in FIG. 17. Here, in the graph shown in FIG. 17, the amplitude shown with a black square and the frequency corresponding to the same amplitude indicate the vibration state caused by the grinding wheel, and the other amplitudes and frequencies corresponding to the same amplitude are mechanical vibrations. shows.

The map generation output unit 344 generates and outputs a map representing the surface texture S (surface texture S1) of the workpiece W in the circumferential direction and the axial direction. Therefore, the map generation output unit 344 obtains the grindstone surface unevenness P which is the second analysis result from the second data analysis processing unit 33 (the grindstone surface unevenness calculation unit 335). Then, as shown in FIG. 18, the map generation output unit 344 generates a map M1 representing the surface texture S11 due to the grindstone surface unevenness P caused by the grindstone, and outputs it as an analysis result A4.

The map generation output unit 344 also obtains the workpiece reference radius R, which is the first analysis result, from the first data analysis processing unit 32 (workpiece reference radius calculation unit 324). Then, as shown in FIG. 19, the map generation output unit 344 generates a map M2 representing the surface texture S12 due to the workpiece reference radius R caused by the grinding wheel, and outputs it as the analysis result A4.

Furthermore, the map generation output unit 344 synthesizes (adds) the map M1 and the map M2. As a result, the map generation/output unit 344 generates a map M3 representing the surface texture S1 caused by the grindstone, as shown in FIG. 20, and outputs it as an analysis result A4.

In this embodiment, a map M3 representing the surface texture S1 caused by the grindstone is generated by combining the map M1 representing the surface texture S11 and the map M2 representing the surface texture S12. However, the map generation output unit 344 can also generate a map representing the surface texture S of the workpiece W by further synthesizing the surface texture S2 caused by center-to-center relative vibration with the generated map M3.

In this case, the map generation output unit 344 acquires the high-frequency inter-center relative vibration waveform HDV from the second data analysis processing unit 33 (high-frequency inter-center relative vibration waveform generation unit 334), and generates the inter-center relative vibration waveform HDV as shown in FIG. A map M4 representing the surface texture S21 due to the high frequency center-to-center relative vibration waveform HDV caused by vibration is generated. In addition, the map generation output unit 344 acquires the low frequency inter-center relative vibration waveform LDV from the first data analysis processing unit 32 (low-frequency inter-center relative vibration waveform generation unit 323), and generates the inter-center relative vibration waveform LDV as shown in FIG. A map M5 representing the surface texture S22 due to the low frequency center-to-center relative vibration waveform LDV caused by the relative vibration is generated. Then, the map generation output unit 344 further synthesizes (adds) the map M4 and the map M5 representing the surface texture S2 caused by the center-to-center relative vibration to the map M3 representing the surface texture S1 caused by the grinding wheel, thereby generating the final result. It is possible to generate a map representing the surface texture S of the workpiece W.

Note that the map generation output unit 344 is not limited to outputting the generated maps M1-M3 (furthermore, the generated maps M4 and M5) as the analysis result A4, but also performs other analyzes based on the generated maps M1-M5. It is also possible to output the result A4. For example, the map generation output unit 344 can output the machining accuracy expressed by the degree of chatter, degree of scale, etc. as the analysis result A4 based on the map M1 representing the surface texture S11.

Then, the output processing unit 34 outputs the plurality of analysis results to the image output device 40. Thereby, the image output device 40 displays each of the plurality of acquired analysis results on, for example, a display.

5. Effects According to the surface texture measuring device 20 of the first embodiment, the damping component c is applied by the damping component applying member 29 to the measurement feeler 22 as a contact member that contacts and relatively slides on the surface of the workpiece W. has been done. As a result, the frequency characteristics of the measurement feeler 22 change, so that the natural vibration characteristics of the measurement feeler 22 and the periodicity of chatter generated on the surface of the workpiece W do not match, and noise is caused in the detection result of the sensor 25. This can be prevented from occurring. As a result, the measurement accuracy of surface texture can be improved.

Further, in the first embodiment, the surface texture measuring device 20 is provided in the sizing device 18 that rotates the workpiece W during grinding by the grinding wheel 12 and measures the diameter of the workpiece W, and is used as a contact member. The measurement feeler 22 constitutes a contactor that contacts the surface of the workpiece W in the sizing device 18. As a result, the measurement feeler 22 as a contact member in the surface texture measuring device 20 is used both for detecting the diameter of the workpiece W in the sizing device 18 and for detecting vibration displacement or acceleration by the sensor 25. , the number of parts can be reduced and the configuration can be simplified compared to the case where a contact member on which the sensor 25 is installed is provided separately from the sizing device 18. Further, the surface texture measuring device 20 can perform in-process measurement while the grinding wheel 12 is in the process of grinding, and can quickly measure the surface texture of the workpiece.

Further, in the first embodiment, the damping component imparting member 29 includes a viscous member that comes into contact with the measurement feeler 22 as a contact member. Thereby, a damping component can be easily applied to the measurement feeler 22 with a simple configuration due to the viscosity of the viscous member.

In addition, the first embodiment includes a housing 26 that holds a measurement feeler 22 and a spring 27 as contact members. The damping component imparting member 29 is interposed between the measurement feeler 22 and the housing 26. Thereby, the attenuation component can be easily applied to the measurement feeler 22 with a simple configuration.

Further, in the first embodiment, the housing 26 has a sealed space 26a containing a part of the measurement feeler 22 as a contact member, and the sealed space 26a is filled with a viscous fluid as a damping component imparting member 29. has been done. Thereby, since the damping component imparting member 29 is a viscous fluid, it is easy to inject into the closed space 26a and also easily enters between the housing 26 and the measurement feeler 22, making it easy to provide the damping component imparting member 29.

Further, in the first embodiment, the sensor 25 detects the vibration acceleration of the measurement feeler 22 as a contact member. Thereby, the sensor 25 can derive a high frequency component in a high frequency region among the frequency components in the measurement result, so that the damping component imparting member 29 can more easily exhibit the vibration damping effect.

Furthermore, in the first embodiment, the surface texture detection system H outputs a two-dimensional map of the surface texture of the workpiece W estimated based on the measurement results by the surface texture measuring device 20 and the surface texture measuring device 20 as an image. An image output device 40 is provided. Thereby, the surface texture of the workpiece W can be easily grasped from the measurement results of the surface texture measuring device 20.

In the first embodiment, the surface texture detection system H has an amplitude peak in a high frequency component in a higher frequency region than a lower frequency component among the frequency components in the measurement result by the surface texture measuring device 20. Reduce. As a result, in the high frequency range where chatter is likely to occur, the peak of the vibration amplitude can be reduced by the damping component imparting member 29, so that it is possible to further suppress the generation of noise in the detection results of the sensor 25, and it is possible to measure the surface texture. Accuracy can be improved.

6. Modifications In Embodiment 1, as shown in FIG. 3, silicone oil was injected into the closed space 26a as the damping component imparting member 29, but instead of this, as in Modification 1 shown in FIG. Rubber, which is a viscous solid, may be interposed as the damping component imparting member 29 between the measurement feeler 22 and the housing 26 as members. Examples of the viscous solid include rubber and elastomer. In the first modification, since the damping component imparting member 29 is solid, it will not leak even if the internal space 26b of the housing 26 is not sealed, and therefore, handling becomes easy. In addition, even in the case of the said modification 1, the same effect as the case of the above-mentioned Embodiment 1 can be produced except the effect by the damping|damping component provision member 29 being a fluid.

Further, in the first embodiment, the surface texture measuring device 20 uses a sizing device provided in the grinding device 10. Instead of this, as a modification, the surface texture measuring device 20 may use a linear gauge. Even in this case, the same effects as in this embodiment described above can be obtained.

Note that the linear gauge is equipped with a gauge head that contacts the workpiece W and an arm that supports the gauge head, and detects the displacement of the surface of the workpiece W while the gauge head is in contact with the rotating workpiece W. It is something. Further, like the sizing device, the linear gauge is supported by an axial movement device and is movable in the axial direction of the workpiece W, that is, in the Z direction.

Furthermore, in the first embodiment, a case has been exemplified in which the sensor 25 of the surface texture measuring device 20 mainly includes an acceleration sensor and detects acceleration as the first measurement data and the second measurement data. The sensor 25 is not limited to mainly including an acceleration sensor, but as a modification, it is also possible to mainly include a displacement sensor that detects displacement due to unevenness on the surface of the workpiece W.

Furthermore, in the first embodiment, the low frequency component extraction unit 321 of the first data analysis processing unit 32 performs FFT, and the spiral low frequency waveform generation unit 322 and the low frequency center-to-center relative vibration waveform generation unit 323 perform inverse FFT. I decided to do it. Further, the spiral high-frequency component extraction unit 331 and the one-section high-frequency component extraction unit 332 of the second data analysis processing unit 33 perform FFT, and the spiral high-frequency waveform generation unit 333 and high-frequency center-to-center relative vibration waveform generation unit 334 perform inverse FFT. I did it like that. Alternatively, in order to omit performing FFT or inverse FFT, it is also possible to provide a filter capable of extracting a desired frequency component in each of the above sections as a modification. Examples of the filter include a low-pass filter, a high-pass filter, a band-pass filter, a Gaussian filter, and the like.

As described above, according to the above-described embodiments and modifications, it is possible to provide a surface texture measuring device that can improve the estimation accuracy of surface texture.

The present invention is not limited to the embodiments and modifications described above, and can be applied to various embodiments without departing from the spirit thereof.

10 Grinding device 12 Grinding wheel 20 Surface texture measuring device 22 Measurement feeler (contact member)
25 Sensor 26 Housing 26a Sealed space 27 Spring 28 Differential transformer 29 Attenuation component imparting member 30 Output device 40 Image output device H Surface texture detection system

Claims (9)

A surface texture measuring device for measuring the surface texture of a workpiece ground by a grinding wheel in a grinding device,
a contact member configured to contact and relatively slide on the surface of the workpiece;
a spring that biases the contact member against the surface of the workpiece;
a sensor that detects at least one of the acceleration of the vibration of the contact member and the displacement of the vibration of the contact member caused by sliding between the contact member and the workpiece;
a damping component imparting member that imparts a damping component to the contact member;
A surface texture measuring device comprising: The surface texture measuring device is installed in a sizing device that rotates the workpiece during grinding by the grinding wheel and measures the diameter of the workpiece,
The surface texture measuring device according to claim 1, wherein the contact member is a contactor that contacts the surface of the workpiece in the sizing device. The surface texture measuring device according to claim 1 or 2, wherein the damping component imparting member includes a viscous member that comes into contact with the contact member. comprising a housing that holds the contact member and the spring;
The surface texture measuring device according to claim 3, wherein the damping component imparting member is interposed between the contact member and the housing. Surface texture measurement according to claim 4, wherein the housing has a sealed space therein that includes a part of the contact member, and the sealed space is filled with a viscous fluid as the damping component imparting member. Device. The surface texture measuring device according to claim 4, wherein the attenuation component imparting member is solid. The surface texture measuring device according to claim 1 or 2, wherein the sensor detects acceleration of vibration of the contact member. The surface texture measuring device according to claim 1 or 2,
an image output device that outputs as an image a two-dimensional map of the surface texture of the workpiece estimated based on the measurement results by the surface texture measuring device;
A surface texture detection system. The surface texture detection according to claim 8, wherein the attenuation component imparting member reduces an amplitude peak in a high frequency component in a high frequency region more than a low frequency component among frequency components in the measurement result measured by the surface texture measuring device. system.

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