In-machine measurement system

Abstract

The in-process measurement system (H) of the present application includes an in-process measurement device (20) and an output device (30). The output device (30) acquires measurement data measured by the in-process measurement device (20) by relatively moving a measurement position on the surface of a workpiece (W) at least in the circumferential direction relative to the workpiece (W), and performs a plurality of analyses related to the machining quality of the workpiece (W) using any one of a low-frequency component, a high-frequency component, and the three of the low-frequency component and the high-frequency component in the frequency component of the measurement data, and outputs a plurality of analysis results.

Description

Technical Field

[0001] This disclosure relates to in-machine measurement systems. Background Technology

[0002] Patent Document 1 describes an example of an automatic dimension measuring device. This automatic dimension measuring device includes a control unit that performs roundness analysis processing. Furthermore, the control unit controls a grinding device to perform dimensional machining on a workpiece based on measurement data obtained from a dimensional measuring device, and analyzes the roundness of the workpiece based on the measurement data from the dimensional measuring device.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2006-153897

[0004] However, the automatic dimension measuring device described in Patent Document 1 only uses measurement data obtained from the dimensional measuring device to analyze roundness. It is desirable to measure the shape of the workpiece, the surface condition after grinding, and the operating state of the grinding device when grinding a workpiece, in order to determine the machining quality of the workpiece after grinding. Therefore, in general, multiple devices are sometimes installed to separately measure the shape of the workpiece, the surface condition after grinding, and the operating state of the grinding device. As a result, the overall system, including the grinding device, becomes complex and expensive, and sometimes it takes time to obtain the desired machining quality. Summary of the Invention

[0005] The purpose of this disclosure is to provide an in-machine measurement system that can obtain grinding quality in a low cost and in a short time during the grinding process.

[0006] The in-machine measurement system comprises: an in-machine measurement device disposed on a grinding apparatus, the in-machine measurement device measuring the surface condition of a workpiece after it has been ground by the grinding apparatus using a grinding wheel, and outputting measurement data representing the surface condition of the workpiece; and an output device acquiring the measurement data measured by the in-machine measurement device by moving the measurement position of the workpiece surface relative to the workpiece at least circumferentially, and using any one of the following three components: low-frequency components in the frequency components of the measurement data, high-frequency components in the frequency components of the measurement data that are higher than the low-frequency components, and low-frequency and high-frequency components in the frequency components of the measurement data, performing multiple analyses related to the processing quality of the workpiece after it has been ground by the grinding apparatus, and outputting multiple analysis results.

[0007] According to the in-machine measurement system, the surface condition of the workpiece can be measured by the in-machine measurement device installed on the grinding machine, and the output device can use the measurement data of any one of the three components—low-frequency component, high-frequency component, and low-frequency component and high-frequency component—obtained from the in-machine measurement device to perform multiple analyses related to the machining quality of the workpiece. Moreover, the output device can output the multiple analysis results obtained through the analysis.

[0008] Therefore, the on-machine measurement system can output multiple analytical results, for example, using only the low-frequency components of the measurement data, using only the high-frequency components of the measurement data, or using both the low-frequency and high-frequency components of the measurement data. Furthermore, the on-machine measurement system can also appropriately combine the low-frequency and high-frequency components to output multiple analytical results, for example, using a first low-frequency component and a second low-frequency component of the measurement data, a first high-frequency component and a second high-frequency component of the measurement data, a first low-frequency component and a second high-frequency component of the measurement data, or a second low-frequency component and a first high-frequency component of the measurement data, etc.

[0009] Therefore, the in-machine measurement system allows for the use of a simple in-machine measurement device that measures the surface condition of a workpiece, thus simplifying the system structure and reducing costs. Furthermore, by appropriately combining the low-frequency and high-frequency components of the measurement data obtained from the in-machine measurement device, the time required to obtain the analysis results can be shortened compared to the case where data is collected from multiple measurement devices and analyzed. Attached Figure Description

[0010] Figure 1 This is a top view showing the structure of the grinding device.

[0011] Figure 2 This is a diagram used to illustrate the in-machine measurement device.

[0012] Figure 3 This is a flowchart illustrating the grinding process of a grinding device.

[0013] Figure 4 It is a diagram used to illustrate the surface properties of a workpiece.

[0014] Figure 5 It is a diagram used to illustrate the surface properties caused by the grinding wheel.

[0015] Figure 6 It is a diagram used to illustrate the surface properties caused by the grinding wheel.

[0016] Figure 7 It is a diagram used to illustrate the surface properties caused by relative vibrations between the hearts.

[0017] Figure 8 This is a block diagram showing the structure of the in-machine measurement system.

[0018] Figure 9 This is a graph used to illustrate the measurement of the first set of data.

[0019] Figure 10 This is a graph used to illustrate the measurement of the second set of data.

[0020] Figure 11 This is a block diagram showing the structure of the first data parsing and processing unit of the output device.

[0021] Figure 12 This is a block diagram showing the structure of the second data parsing and processing unit of the output device.

[0022] Figure 13 This is a block diagram showing the structure of the output processing section of the output device.

[0023] Figure 14 It is a diagram used to illustrate the analytical results of the output processing unit related to the shape of the workpiece.

[0024] Figure 15 It is a diagram used to illustrate the analytical results related to the mechanical state of the output processing unit.

[0025] Figure 16 This is a graph used to illustrate the analytical results (figures) related to the processing quality of the output processing unit.

[0026] Figure 17 This is a graph used to illustrate the analytical results (figures) related to the processing quality of the output processing unit.

[0027] Figure 18 This is a graph used to illustrate the analytical results (figures) related to the processing quality of the output processing unit.

[0028] Figure 19 This is a graph used to illustrate the analytical results (figures) related to the processing quality of the output processing unit.

[0029] Figure 20 This is a graph used to illustrate the analytical results (figures) related to the processing quality of the output processing unit. Detailed Implementation

[0030] The in-system measurement system H will now be described with reference to the accompanying drawings. Figure 1 As shown, the in-machine measurement system H includes a grinding device 10, an in-machine measurement device 20, and an output device 30. Additionally, the in-machine measurement system H in this example includes an image output device 40.

[0031] In the in-machine measurement system H of this example, the in-machine measurement device 20 measures the surface (grinding surface) of the workpiece W during or after grinding by the grinding device 10. The output device 30 performs various data analysis processes based on the measurement data measured by the in-machine measurement device 20 and outputs multiple analysis results related to the processing quality of the workpiece W. Furthermore, the image output device 40 in this example outputs the multiple analysis results output from the output device 30 as an image.

[0032] Here, the measurement data detected by the in-machine measuring device 20 can include, for example, the acceleration and displacement (amplitude) of vibrations that occur corresponding to the surface condition (surface properties) of the workpiece W. Furthermore, the in-machine measuring device 20 can measure the measurement data by direct or indirect contact with the workpiece W, and can also measure the measurement data without contact with the workpiece W (through non-contact measurement). In this example, the measurement of displacement on the surface of the workpiece W and the acceleration related to that displacement by the in-machine measuring device 20 is illustrated and explained.

[0033] (1. Structure of grinding device 10)

[0034] like Figure 1 as well as Figure 2 As shown, the grinding apparatus 10 includes a base 11, a grinding wheel 12, a grinding wheel holder 13, a spindle box 14, a tailstock 15, a spindle table 16, and a controller 17, and also includes an in-machine measuring device 20. The workpiece W is supported at both ends in the direction of rotation by the spindle box 14 and the tailstock 15 and rotates. Furthermore, in this example, the workpiece W is shown to be cylindrical or cylindrical. The grinding apparatus 10 brings the grinding wheel 12 into contact with the surface (outer circumferential surface) of the rotating workpiece W and performs grinding, thereby forming the shape of the workpiece W.

[0035] The grinding wheel 12 is rotatably supported on the grinding wheel holder 13 about an axis parallel to the Z-axis. A grinding wheel holder guide 11a is fixed on the base 11, and the grinding wheel holder 13 is movably supported on the grinding wheel holder guide 11a in the X-axis direction. A grinding wheel rotation motor 12a, controlled by the controller 17, provides rotational driving force to the grinding wheel 12, causing the grinding wheel 12 to rotate about the rotation axis. The grinding wheel 12 moves in the X-axis direction via the grinding wheel holder 13, approaching the workpiece W which is separated in the X-axis direction, and grinding the workpiece W.

[0036] On the base 11, the spindle table guide 11b is fixed in a position separated from the grinding wheel guide 11a in the X-axis direction. The spindle table guide 11b supports the spindle table 16 so that it is movable in the Z-axis direction. The spindle head 14 and the tailstock 15 are arranged opposite each other on the spindle table 16. The workpiece W is rotatably supported at both ends by the spindle head 14 and the tailstock 15, and rotates by being driven by the spindle rotary motor 14a controlled by the controller 17.

[0037] (2. Structure of the in-machine measuring device 20)

[0038] In this example, the in-machine measuring device 20 is configured to include a so-called calibrating device. For example... Figure 1 as well as Figure 2 As shown, the in-machine measuring device 20 includes: a pair of probes 21 serving as contact portions that contact the surface of the workpiece W; and a pair of finger-like portions 22 supporting the probes 21. Figure 2 As shown, the probe 21 is configured to abut against the surface of the workpiece W at two points, with the rotation center O clamping the workpiece W. A pair of finger-like portions 22 have the probe 21 at their front ends, and these portions can be replaced by attaching and detaching the base portions. Furthermore, the on-machine measuring device 20 is supported by the axial movement device 23 and can move along the axial direction of the workpiece W, i.e., the Z-axis direction. The Z-axis movement of the on-machine measuring device 20 is controlled by the axial movement control unit 24. Moreover, the movement in the Z-axis direction is not limited to the axial movement device 23; for example, the displacement functions of the spindle and tailstock spindle of the grinding device 10 can also be used.

[0039] The in-machine measuring device 20 measures the unevenness of the outer periphery of the workpiece W, which is the surface condition of the workpiece W, by converting the mechanical displacement of the probe 21 into an electrical signal related to displacement and acceleration. Here, the in-machine measuring device 20 measures the outer diameter of the workpiece W, i.e., the surface condition of the workpiece W, in a frequency region of less than 60 Hz. That is, the in-machine measuring device 20 is able to measure the low-frequency components in the frequency characteristics of the surface condition of the workpiece W.

[0040] Furthermore, the in-machine measuring device 20 includes a high-frequency component measuring device 25 assembled on at least one of the pair of finger portions 22. In this example, the high-frequency component measuring device 25 mainly includes an acceleration sensor added by being assembled on the finger portion 22, and measures the acceleration related to the displacement value of the surface state of the workpiece W in a frequency region, for example, above 60 Hz, of the frequency characteristics of the surface state of the workpiece W. That is, the high-frequency component measuring device 25 measures the acceleration accompanying the displacement (vibration) generated in the finger portion 22 when the probe 21 moves relative to the workpiece W while in contact with the surface of the workpiece W, as a high-frequency component in the frequency characteristics of the surface state of the workpiece W that is higher than the low-frequency component.

[0041] Here, in this example, the high-frequency component measuring device 25 is illustrated by using an acceleration sensor assembled (added) to the finger portion 22. However, the high-frequency component measuring device 25 is not limited to adding an acceleration sensor; for example, devices such as analog output amplifiers that omit the low-pass filter or high-frequency digital output amplifiers provided in the calibrating device can be used. In this case, the on-machine measuring device 20 measures displacement rather than acceleration, so the process of converting acceleration into displacement described later is unnecessary.

[0042] (3. Grinding process of workpiece W by grinding device 10)

[0043] Grinding device 10 via Figure 3The workpiece W is ground using multiple processes, as shown. The grinding processes are divided according to the different feed rates of the grinding wheel, and are performed in the following order: rough grinding (St1), fine grinding (St2), micro-grinding (St3), and sparkless grinding (St4). The feed rates of the grinding wheel in each process are: rough grinding (St1) > fine grinding (St2) > micro-grinding (St3) > sparkless grinding (St4). In the rough grinding (St1) process, the approximate shape of the workpiece W is formed. In the subsequent fine grinding (St2) and micro-grinding (St3) processes, the surface shape of the workpiece W is adjusted while decreasing the feed rate. In the final sparkless grinding (St4) process, the surface of the workpiece W is finished, thus completing the workpiece W.

[0044] Here, for the in-machine measurement system H, it is preferable that the in-machine measurement device 20 measures the surface condition of the workpiece W during the grinding process, i.e., from the rough grinding step St1 to the sparkless grinding step St4, or after the sparkless grinding step St4 is completed. Furthermore, during the process, the in-machine measurement system H outputs multiple analytical results related to machining quality, as described later. "During the process" refers to the period until the workpiece W is removed from the grinding device 10, including after the sparkless grinding step St4.

[0045] (4. Overview of output device 30)

[0046] Next, a general overview of the output device 30 will be provided. For example... Figure 4 As shown, the surface property S, one of the machining qualities of the workpiece W ground by the grinding device 10, is determined by various factors. That is, the surface property S of the workpiece W is a combination of surface property S1 and surface property S2, where surface property S1 is as follows: Figure 4 The solid line and double-dotted line in the middle represent the surface characteristics caused by the grinding wheel, which are transferred from the surface state of the grinding surface of the grinding wheel 12. This surface characteristic S2 is as follows: Figure 4 The dotted line in the middle represents the surface characteristics caused by the relative vibration between the grinding wheel 12 and the workpiece W, which is transferred by the vibration generated by the relative movement between the grinding wheel 12 and the workpiece W.

[0047] Furthermore, the surface properties S, namely surface properties S1 and surface properties S2, are measured by the in-machine measurement device 20 as measurement data. Here, the measurement data measured by the in-machine measurement device 20 includes the low-frequency components measured by the probe 21 and the high-frequency components measured by the high-frequency component measurement device 25. Therefore, it can be said that the surface properties S are determined by the synthesis of low-frequency and high-frequency components.

[0048] The surface characteristics S1 caused by the grinding wheel are the circumferential and axial surface characteristics of the workpiece W, such as... Figure 5 as well as Figure 6As shown, the surface characteristic S11, which is a high-frequency component of the unevenness of the grinding wheel surface, and the surface characteristic S12, which includes a low-frequency component and is static, are combined. Here, the surface characteristic S11 reflects, for example, the machining accuracy such as the circumferential vibration caused by the unevenness of a cross section of the workpiece W by the grinding wheel (hereinafter referred to as "vibration degree") and the degree of deviation of the vibration degree in the axial direction of the workpiece W (hereinafter referred to as "scalyness").

[0049] In addition, the surface property S2 caused by the relative vibration between the cores is the circumferential surface property of a cross section of the workpiece W, such as... Figure 7 As shown, the surface property S2 is synthesized from low-frequency and high-frequency components. That is, the surface property S2 is synthesized from the surface property S21, which is a high-frequency component, and the surface property S22, which is a low-frequency component. Here, the surface property S2 reflects, for example, the shape of the workpiece W, which depends on the machining accuracy such as roundness, the amount of vibration of the grinding surface, and coaxiality, as well as the mechanical state and machining state such as the vibration of the grinding device 10, the self-excited vibration during machining, and the sparkless grinding effect.

[0050] Therefore, in this example, the output device 30 extracts low-frequency and high-frequency components from the measurement data measured by the in-machine measurement device 20. Then, the output device 30 performs various data analysis processes on the extracted (acquired) low-frequency and high-frequency components and outputs multiple analysis results using various data analysis processes.

[0051] (4-1. Structure of output device 30)

[0052] like Figure 8 As shown, the output device 30 includes a basic data acquisition unit 31, a first data parsing and processing unit 32, a second data parsing and processing unit 33, and an output processing unit 34. The output device 30 may also include, for example, a processor and a memory storing instructions such as a program, so that when the processor executes instructions, the computer can perform the operations of the basic data acquisition unit 31, the first data parsing and processing unit 32, the second data parsing and processing unit 33, and the output processing unit 34.

[0053] (4-2. Basic Data Acquisition Section 31)

[0054] The basic data acquisition unit 31 acquires measurement data (displacement and acceleration) detected by the on-machine measurement device 20 during or after grinding. Specifically, such as... Figure 8 As shown, the basic data acquisition unit 31 acquires the first measurement data K1 output from the on-machine measurement device 20 as the first basic data D1, and acquires the second measurement data K2 as the second basic data D2.

[0055] Here, as Figure 9As shown, the on-machine measuring device 20 first detects first measurement data K1 when the measuring position moves helically relative to the workpiece W in both the circumferential and axial directions, and outputs it to the basic data acquisition unit 31. The measuring position is the position where the displacement and acceleration corresponding to the surface state of the workpiece W are measured. That is, when acquiring the first basic data D1, while the workpiece W is rotating, the probe 21 of the on-machine measuring device 20 contacts the surface of the workpiece W, and the on-machine measuring device 20 is continuously moved along the axial direction of the workpiece W by the axial movement device 23. Here, the measuring position in this example is the position where the probe 21 of the on-machine measuring device 20 contacts the surface of the workpiece W. Furthermore, the first measurement data K1 includes measurement data of low-frequency components (displacement) and measurement data of high-frequency components (acceleration) measured by the high-frequency component measuring device 25.

[0056] In addition, such as Figure 10 As shown, the on-machine measuring device 20 detects a second measurement data K2 of one revolution of the outer circumference of the workpiece W when the measuring position is either in the same position axially (same axial position) or moved separately axially without moving the measuring position in a spiral manner, and outputs it to the basic data acquisition unit 31. That is, while the workpiece W is rotating, the probe 21 of the on-machine measuring device 20 is brought into contact with the surface of the workpiece W, and the on-machine measuring device 20 is stopped at the same axial position of the workpiece W by the axial movement device 23. Here, the second measurement data K2 includes measurement data of low-frequency components (displacement) and measurement data of high-frequency components (acceleration) measured by the high-frequency component measuring device 25.

[0057] The basic data acquisition unit 31 acquires first measurement data K1, which is detected in a spiral pattern, as first basic data D1. Additionally, the basic data acquisition unit 31 acquires second measurement data K2, which is measured at the same position along the axial direction for one revolution, as second basic data D2. Then, the basic data acquisition unit 31 outputs the first basic data D1 and the second basic data D2 to the first data analysis processing unit 32 and the second data analysis processing unit 33, respectively.

[0058] Here, the first basic data D1 and the second basic data D2 are time-series data related to displacement and acceleration. Furthermore, the first basic data D1 and the second basic data D2 are generally obtained as data based on the time axis, but can also be converted to data based on the rotation angle of the workpiece W, depending on time and the rotational speed of the workpiece W.

[0059] (4-3. First Data Parsing and Processing Unit 32)

[0060] The first data analysis and 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 later) on the extracted low-frequency components to calculate multiple first analysis results. Therefore, as... Figure 11 As shown, the first data analysis and processing unit 32 mainly includes a low-frequency component extraction unit 321, a spiral low-frequency waveform generation unit 322, a low-frequency intercentric relative vibration waveform generation unit 323, and a workpiece reference radius calculation unit 32.

[0061] The low-frequency component extraction unit 321 performs a Fast Fourier Transform (FFT) on the first basic data D1 obtained from the basic data acquisition unit 31 and extracts the low-frequency component D11 from the frequency characteristics of the first basic data D1. Additionally, the low-frequency component extraction unit 321 performs an FFT on the second basic data D2 obtained from the basic data acquisition unit 31 and extracts the low-frequency component D21 from the frequency characteristics of the second basic data D2 as a first analytical result. Here, the low-frequency component extraction unit 321 extracts, for example, the low-frequency components of the first basic data D1 and the second basic data D2, which fall within a frequency range of less than 60Hz (approximately 15 to 50 peaks on the waveform), as the low-frequency components.

[0062] The spiral low-frequency waveform generation unit 322 performs an 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 the first measurement data K1 (displacement) detected by the on-machine measuring device 20 along the outer peripheral surface (surface) of the workpiece W in a spiral shape. As a result, the spiral low-frequency waveform generation unit 322 calculates the spiral low-frequency waveform SLW, which represents the waveform of the low-frequency component D11 representing the displacement variation, i.e., vibration, in the spiral direction of the workpiece W, as the first analytical result.

[0063] The low-frequency intercentric relative vibration waveform generation unit 323 performs an inverse FFT on the low-frequency component D21 of the second basic data D2 extracted by the low-frequency component extraction unit 321. Here, the second basic data D2 is the second measurement data K2 (displacement) detected by the in-machine measuring device 20 at the same position along the axial direction of the workpiece W. Therefore, by performing an inverse FFT on the low-frequency component D21 of the second basic data D2, a cross-sectional low-frequency waveform representing the displacement variation, i.e., vibration, of the low-frequency component D21 in the circumferential direction (1 circumference) of the workpiece W can be obtained.

[0064] However, a cross-sectional low-frequency waveform can, for example, represent the relative vibration (low-frequency inter-core relative vibration) caused by the change in the relative position, i.e., the inter-core distance, between the grinding wheel 12 and the workpiece W, which is relatively stable during the grinding of a workpiece W due to factors such as pump pulsation in the grinding apparatus 10 and the setting accuracy of the workpiece W. For a workpiece W, this distance can be considered the same along the axial direction of the workpiece W. Therefore, the low-frequency inter-core relative vibration waveform generation unit 323 calculates a cross-sectional low-frequency waveform obtained by performing an inverse FFT as the first analytical result, i.e., the low-frequency inter-core relative vibration waveform LDV.

[0065] The workpiece reference radius calculation unit 324 uses the helical low-frequency waveform SLW generated by the helical low-frequency waveform generation unit 322 and the low-frequency inter-core relative vibration waveform LDV generated by the low-frequency inter-core relative vibration waveform generation unit 323 to calculate the workpiece reference radius R caused by the surface condition of the grinding surface of the grinding wheel 12 transferred onto the surface of the ground workpiece W. Specifically, the workpiece reference radius calculation unit 324 calculates the workpiece reference radius R by subtracting the low-frequency inter-core relative vibration waveform LDV from the helical low-frequency waveform SLW as the first analytical result.

[0066] Here, as described above, the low-frequency inter-core relative vibration waveform LDV is considered to be a low-frequency waveform with the same cross-section along the axial direction of the workpiece W. Therefore, the workpiece reference radius calculation unit 324 calculates the workpiece reference radius R according to the following formula 1, by adding (copying) a number of low-frequency inter-core relative vibration waveforms LDV that are consistent with the number of helical cycles C of the helical low-frequency waveform SLW, and subtracting the added value from the helical low-frequency waveform SLW.

[0067] R = SLW - C × LDV…Equation 1

[0068] (4-4. Second Data Parsing and Processing Unit 33)

[0069] The second data analysis and 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 on the extracted high-frequency components as described later to calculate multiple second analysis results. Therefore, as... Figure 12 As shown, the second data parsing and processing unit 33 mainly includes a spiral high-frequency component extraction unit 331, a cross-section high-frequency component extraction unit 332, a spiral high-frequency waveform generation unit 333, a high-frequency inter-core relative vibration waveform generation unit 334, and a grinding wheel surface concavity and convexity calculation unit 335.

[0070] The spiral high-frequency component extraction unit 331 extracts the high-frequency component from the frequency characteristics of the first basic data D1 obtained from the basic data acquisition unit 31 by performing an FFT on the first basic data D1 and converting the acceleration data into displacement data, thereby using it as the spiral high-frequency component D12. Here, the first basic data D1 is the first measurement data K1 (acceleration) detected by the on-machine measuring device 20 along the outer peripheral surface of the workpiece W in a spiral shape. In addition, for the spiral high-frequency component extraction unit 331, the frequency characteristics in the frequency range above 60Hz and below the detection upper limit of the on-machine measuring device 20 (approximately 50 to 500 peaks in the waveform) are extracted as the spiral high-frequency component D12.

[0071] A cross-sectional high-frequency component extraction unit 332 extracts a high-frequency component D22 from the frequency characteristics of the second basic data D2 obtained from the basic data acquisition unit 31 by performing an FFT on the second basic data D2 and converting the acceleration data into displacement data. Furthermore, the cross-sectional high-frequency component extraction unit 332 extracts a high-frequency component D221 from the extracted high-frequency component D22 after removing the grinding wheel rotation frequency component fg corresponding to the rotational speed of the grinding wheel 12 and its higher harmonics.

[0072] Here, the second basic data D2 is the second measurement data K2 (acceleration) detected by the in-machine measuring device 20 at the same position along the axial direction of the workpiece W. Therefore, the high-frequency component extracted from the second basic data D2 corresponds to one circumference, i.e., one cross-section of the workpiece W, in the circumferential direction of the workpiece W. Furthermore, for the high-frequency component extraction unit 332 of one cross-section, as a high-frequency component, for example, a frequency range above 60Hz and below the detection upper limit of the in-machine measuring device 20 (approximately 50 to 500 peaks in the waveform) is also extracted as the high-frequency component D22.

[0073] The spiral high-frequency waveform generation unit 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 unit 331. As a result, the spiral high-frequency waveform generation unit 333 calculates the spiral high-frequency waveform SHW, representing the waveform of the spiral high-frequency component D12, which indicates the displacement variation (i.e., vibration) of the workpiece W in the spiral direction, as the second analytical result.

[0074] The high-frequency inter-core relative vibration waveform generation unit 334 performs an inverse FFT on a cross-sectional high-frequency component D221 of the second basic data D2 extracted by the cross-sectional high-frequency component extraction unit 332. Thus, if an inverse FFT is performed on the cross-sectional high-frequency component D221 obtained by removing the grinding wheel rotation frequency component fg and its higher harmonics from the high-frequency component of the second basic data D2, a cross-sectional high-frequency waveform representing the displacement variation, i.e., vibration, of the cross-sectional high-frequency component D221 of the workpiece W can be obtained.

[0075] However, the high-frequency component D221 of a cross section does not include the grinding wheel rotation frequency component fg corresponding to the rotational speed of the grinding wheel 12 and its higher harmonics. Therefore, the high-frequency waveform of a cross section represents vibrations that affect the surface properties S of the workpiece W (more specifically, the surface properties S22 in the surface properties S2 caused by inter-core relative vibrations), other than the grinding wheel rotation frequency component fg corresponding to the rotational speed of the grinding wheel 12 and its higher harmonics. Here, vibrations that affect the surface properties S22 of the workpiece W can be exemplified by, for example, the rotation of the servo motor that controls the movement of the grinding wheel holder 13 and the spindle table 16, externally applied vibrations, self-excited vibrations, etc.

[0076] Therefore, a cross-sectional high-frequency waveform represents the relative vibration (high-frequency inter-core relative vibration) caused by the change in the high-frequency region of the relative position, i.e., the inter-core distance, between the grinding wheel 12 and the workpiece W. Similar to a cross-sectional low-frequency waveform, the same waveform can be considered along the axial direction of the workpiece W. Therefore, the high-frequency inter-core relative vibration waveform generation unit 334 calculates a cross-sectional high-frequency waveform obtained by performing an inverse FFT, and uses this as the second analytical result, i.e., the high-frequency inter-core relative vibration waveform HDV.

[0077] The grinding wheel surface unevenness calculation unit 335 uses the helical high-frequency waveform SHW generated by the helical high-frequency waveform generation unit 333 and the high-frequency inter-core relative vibration waveform HDV generated by the high-frequency inter-core relative vibration waveform generation unit 334 to calculate the grinding wheel surface unevenness P caused by the surface condition of the grinding surface of the grinding wheel 12 transferred to the outer peripheral surface of the workpiece W after grinding. Specifically, the grinding wheel surface unevenness calculation unit 335 calculates the grinding wheel surface unevenness P by subtracting the high-frequency inter-core relative vibration waveform HDV from the helical high-frequency waveform SHW as a second analytical result.

[0078] Here, as described above, the high-frequency inter-core relative vibration waveform HDV is considered to be a high-frequency waveform with the same cross-section along the axial direction of the workpiece W. Therefore, the grinding wheel surface unevenness calculation unit 335 calculates the grinding wheel surface unevenness P by adding (copying) a number of high-frequency inter-core relative vibration waveforms HDV that are consistent with the number of helical cycles C of the helical high-frequency waveform SHW, and subtracting the added value from the helical high-frequency waveform SHW, according to the following formula 2.

[0079] P = SHW - C × HDV…Equation 2

[0080] (4-5. Output Processing Unit 34)

[0081] The output processing unit 34 can process and output multiple parsing results using multiple first calculation results calculated by the first data parsing processing unit 32 and multiple second calculation results calculated by the second data parsing processing unit 33. The multiple parsing results output will be illustrated and explained below.

[0082] The multiple analytical results output by the output processing unit 34 are related to the machining quality of the workpiece W after grinding by the grinding apparatus 10. As machining quality, examples related to the surface properties S2 described above include the roundness of the workpiece W, the amount of vibration on the grinding surface, and the coaxiality of the workpiece W, etc., representing the shape (machining accuracy) of the workpiece W. Furthermore, regarding machining quality, examples include the machining state of the grinding apparatus 10 and the mechanical state of the grinding apparatus 10. The machining state includes machining accuracy, and examples include sparkless grinding and the sharpness of the grinding wheel 12. As for the mechanical state, examples include the vibration of the grinding apparatus 10 (mechanical vibration).

[0083] Furthermore, these processing qualities, processing conditions, and mechanical conditions are analytical results obtained from second measurement data K2 (second basic data D2) measured at the same axial position during the grinding of workpiece W using the in-machine measurement device 20. Therefore, these analytical results are output for each grinding of workpiece W by the grinding device 10, i.e., for all workpieces W.

[0084] Furthermore, as a machining quality, examples include the surface properties S (surface properties S1) and line roughness of the workpiece W, which are included in the machining accuracy. Moreover, these machining qualities (machining accuracy) are analytical results obtained after the workpiece W has been ground, using the on-machine measuring device 20 to measure first measurement data K1 (first basic data D1) in the circumferential and axial directions of the workpiece W, and second measurement data K2 (second basic data D2) at the same position in the axial direction. Therefore, these analytical results can be appropriately output as needed, for example, after the workpiece W has been ground.

[0085] like Figure 13 As shown, the output processing unit 34 in this example includes: a shape analysis output unit 341 that outputs analysis results related to processing quality; a processing state output unit 342 that outputs analysis results related to processing state; a machine state output unit 343 that outputs analysis results related to machine state; and a graph generation output unit 344 that outputs analysis results related to processing quality.

[0086] Here, the shape analysis output unit 341, the machining status output unit 342, and the machine status output unit 343 use the low-frequency and high-frequency components of the second measurement data K2 (second basic data D2) measured by the on-machine measuring device 20 at the same position along the axial direction of the workpiece. On the other hand, the drawing generation output unit 344 uses the low-frequency and high-frequency components of the first measurement data K1 (first basic data D1) measured by the on-machine measuring device 20 in the circumferential and axial directions of the workpiece W, and the low-frequency and high-frequency components of the second measurement data K2 (second basic data D2) measured at the same position along the axial direction of the workpiece.

[0087] The shape analysis output unit 341 obtains the low-frequency intercardiac relative vibration waveform (LDV) as the first analysis result from the first data analysis processing unit 32 (low-frequency intercardiac relative vibration waveform generation unit 323), and obtains the high-frequency intercardiac relative vibration waveform (HDV) as the second analysis result from the second data analysis processing unit 33 (high-frequency intercardiac relative vibration waveform generation unit 334). Then, the shape analysis output unit 341 combines (adds) the low-frequency intercardiac relative vibration waveform (LDV) and the high-frequency intercardiac relative vibration waveform (HDV) to obtain the result as shown in the figure. Figure 14 As shown, the roundness of a cross section of workpiece W and the amount of jitter on the ground surface are output as the analysis result A1. Furthermore, for example, if multiple roundness values ​​and jitter values ​​are analyzed along the axial direction of workpiece W, the coaxiality of workpiece W can also be output.

[0088] The machining status output unit 342 outputs the speed ratio, which represents the ratio of the rotational speeds of the grinding wheel 12 and the workpiece W, as the analysis result A2 for evaluation. Figure 3 The grinding effects of each grinding process are shown. Therefore, for each grinding process, the processing status output unit 342 obtains the high-frequency component D22 of the second basic data D2 from the second data analysis and processing unit 33 (a cross-section high-frequency component extraction unit 332) as the second analysis result.

[0089] For example, when evaluating the grinding effect of the sparkless grinding process St4, the machining status output unit 342 outputs... Figure 3 The ratio (fg2 / fg1) of the wheel rotation frequency component fg2 in the sparkless grinding process St4 to the wheel rotation frequency component fg1 in the rough grinding process St1 is used as the analytical result A2. In this case, the evaluation can be performed as follows: the closer the output analytical result A2 (fg2 / fg1) is to "0", the higher the grinding effect of the sparkless grinding process St4; the closer it is to "1", the lower the grinding effect of the sparkless grinding process St4.

[0090] The mechanical state output unit 343 obtains the low-frequency component D21 of the second basic data D2 from the first data analysis processing unit 32 (low-frequency component extraction unit 321) as the first analysis result, and obtains the high-frequency component D22 of the second basic data D2 from the second data analysis processing unit 33 (one-section high-frequency component extraction unit 332) as the second analysis result. Then, as... Figure 15 As shown, the relationship between the output frequency change and amplitude of the mechanical state output unit 343 is used as the analytical result A3. Here, in Figure 15 In the chart shown, the black squares represent the amplitude and the corresponding frequency of the same amplitude, indicating the vibration state caused by the grinding wheel. Other amplitudes and the corresponding frequencies of the same amplitude represent mechanical vibration.

[0091] The image generation output unit 344 generates and outputs a map representing the circumferential and axial surface characteristics S (surface characteristics S1) of the workpiece W. Therefore, the image generation output unit 344 obtains the grinding wheel surface unevenness P as a second analysis result from the second data analysis processing unit 33 (grinding wheel surface unevenness calculation unit 335). Then, as... Figure 16 As shown, the graph generation output unit 344 generates a graph M1 representing the surface characteristics S11 of the grinding wheel surface unevenness P caused by the grinding wheel, and outputs it as the analysis result A4.

[0092] Additionally, the drawing generation output unit 344 obtains the workpiece reference radius R as the first analysis result from the first data parsing processing unit 32 (workpiece reference radius calculation unit 324). Then, as... Figure 17 As shown, the graph generation output unit 344 generates a graph M2 representing the surface characteristics S12 based on the workpiece reference radius R caused by the grinding wheel, and outputs it as the analysis result A4.

[0093] Furthermore, the graph generation output unit 344 combines (adds) graph M1 and graph M2. Thus, as... Figure 18 As shown, the graph generation output unit 344 generates a graph M3 representing the surface properties S1 caused by the grinding wheel and outputs it as the analysis result A4.

[0094] Here, in this example, by combining the graph M1 representing surface condition S11 and the graph M2 representing surface condition S12, a graph M3 representing the surface condition S1 caused by the grinding wheel is generated. However, the graph generation output unit 344 can also further combine the surface condition S2 caused by inter-center relative vibration with the generated graph M3 to generate a graph representing the surface condition S of the workpiece W.

[0095] In this case, the graph generation output unit 344 obtains the high-frequency intercardiac relative vibration waveform HDV from the second data analysis and processing unit 33 (high-frequency intercardiac relative vibration waveform generation unit 334), such as Figure 19 As shown, Figure M4 is generated, representing the surface characteristics S21 based on the high-frequency intercardiac relative vibration waveform HDV caused by intercardiac relative vibration. Additionally, the figure generation output unit 344 obtains the low-frequency intercardiac relative vibration waveform LDV from the first data parsing processing unit 32 (low-frequency intercardiac relative vibration waveform generation unit 323), as shown. Figure 20 As shown, a graph M5 representing the surface characteristics S22 based on the low-frequency inter-centric relative vibration waveform LDV caused by inter-centric relative vibration is generated. Then, the graph generation output unit 344 further combines (adds) graphs M4 and M5 representing the surface characteristics S2 caused by inter-centric relative vibration with graph M3 representing the surface characteristics S1 caused by the grinding wheel, thereby finally generating a graph representing the surface characteristics S of the workpiece W.

[0096] Furthermore, the image generation output unit 344 is not limited to outputting the generated images M1-M3 (and the generated images M4 and M5) as the analysis result A4, but can also output other analysis results A4 based on the generated images M1-M5. For example, the image generation output unit 344 can output the processing accuracy represented by vibration degree, scale degree, etc. as the analysis result A4 based on the image M1 representing the surface properties S11.

[0097] Then, the output processing unit 34 outputs multiple analysis results to the image output device 40. The image output device 40 then displays the acquired multiple analysis results, for example, on a display screen.

[0098] As can be understood from the above description, according to the in-machine measurement system H, the surface condition of the workpiece W can be measured by the in-machine measurement device 20, which is formed by using the dimensional device provided on the grinding device 10 and the high-frequency component measuring device 25 assembled on the dimensional device. The output device 30 uses the low-frequency and high-frequency components of the first measurement data K1 (first basic data D1) obtained from the in-machine measurement device 20, and the low-frequency and high-frequency components of the second measurement data K2 (second basic data D2) to perform multiple analyses related to the processing quality of the workpiece W.

[0099] Furthermore, the output device 30 can output multiple analytical results A1-A4 obtained through analysis. Therefore, according to the in-machine measurement system H, the in-machine measurement device 20, with its simple structure for measuring the surface condition of the workpiece W, can be used, thus simplifying the system structure and reducing costs. Additionally, according to the in-machine measurement system H, by using the first measurement data K1 (first basic data D1) and the second measurement data K2 (second basic data D2) measured by the in-machine measurement device 20, the time required to obtain the analytical results A1-A4 can be shortened, for example, compared to the case where analytical data is collected from multiple measurement devices.

[0100] More specifically, the output device 30 can perform multiple analyses using the low-frequency component D11 and the spiral high-frequency component D12 (which is a high-frequency component) of the frequency components of the first basic data D1 (first measurement data K1) detected in a spiral pattern, and the low-frequency component D21 and the high-frequency component D22 of the frequency components of the second basic data D2 (second measurement data K2) detected at the same position in the axial direction. Furthermore, the output device 30 can output an analysis result A1 related to the shape of the workpiece W, an analysis result A2 related to the processing state, and an analysis result A3 related to the mechanical state during the grinding of the workpiece W, as multiple analysis results related to processing quality. Additionally, after grinding, the output device 30 can also, as needed, visualize the surface characteristics of the workpiece W related to processing quality and output it as an analysis result A4.

[0101] Therefore, by utilizing the analysis results A1-A4, for example by monitoring the analysis results A1-A3, it is possible to prevent the sudden outflow of defective workpieces W due to dust or other contaminants entering the grinding device 10. Furthermore, by utilizing the analysis results A1-A4, anomalies occurring in the grinding device 10 can be detected in advance, the causes can be analyzed, and countermeasures can be taken proactively. Moreover, by utilizing the analysis results A1-A4, maintenance of the grinding device 10 can also be achieved, such as optimizing the dressing interval, thereby reducing the manufacturing cost of workpiece W.

[0102] (5. Other examples)

[0103] In the example above, the in-machine measuring device 20 uses a dimensional device provided on the grinding apparatus 10. Alternatively, the in-machine measuring device 20 can use a linear gauge. In this case, the same effect as in the example above can be obtained.

[0104] Furthermore, in the above example, the high-frequency component measuring device 25 of the in-machine measuring apparatus 20 is illustrated as mainly equipped with an acceleration sensor to detect acceleration as the first and second measurement data. The high-frequency component measuring device 25 is not limited to mainly equipped with an acceleration sensor; it may also mainly be equipped with a displacement sensor that detects displacement caused by the unevenness of the surface of the workpiece W.

[0105] Displacement sensors included in the high-frequency component measuring device 25 can include, for example, contact-type dimensional devices, linear gauges, or non-contact types such as laser sensors, optical sensors, and eddy current sensors. Contact-type dimensional devices and linear gauges have contact components such as a probe 21 that contacts the surface of the workpiece W, and detect the displacement caused by the vibration of the contact components as the workpiece W rotates. Non-contact types such as laser sensors, optical sensors, and eddy current sensors are configured to not contact the surface of the workpiece W, and detect the displacement from a reference position to the surface of the workpiece W as the workpiece W rotates.

[0106] The displacement of the contact component detected by the contact-type sensor and the displacement detected by the non-contact-type sensor are both measurement data (time series data) representing the displacement of the surface unevenness of the workpiece. Therefore, even in this case, the measurement data (displacement) output from the on-machine measuring device 20 is also time series data, and the basic data acquisition unit 31 acquires the first measurement data K1 and the second measurement data K2 output from the on-machine measuring device 20 as the first basic data D1 and the second basic data D2, respectively.

[0107] Furthermore, the linear gauge has a probe that contacts the workpiece W and an arm that supports the probe, allowing it to detect the displacement of the workpiece W's surface while the probe is in contact with the rotating workpiece W. Additionally, the linear gauge, like the dimensional measuring device, is supported by an axial movement mechanism, enabling it to move along the axial direction of the workpiece W, i.e., the Z-direction.

[0108] Furthermore, in the above example, the low-frequency component extraction unit 321 of the first data analysis and processing unit 32 performs FFT, while the spiral low-frequency waveform generation unit 322 and the low-frequency intercentric relative vibration waveform generation unit 323 perform inverse FFT. Additionally, the spiral high-frequency component extraction unit 331 and the cross-sectional high-frequency component extraction unit 332 of the second data analysis and processing unit 33 perform FFT, while the spiral high-frequency waveform generation unit 333 and the high-frequency intercentric relative vibration waveform generation unit 334 perform inverse FFT.

[0109] In this way, filters capable of extracting the desired frequency components can be set in the aforementioned parts, thus eliminating the need for FFT or inverse FFT. Examples of such filters include low-pass filters, high-pass filters, band-pass filters, and Gaussian filters.

[0110] This application is based on Japanese Patent Application No. 2021-011364, filed on January 27, 2021, the contents of which are incorporated herein by reference.

[0111] Explanation of reference numerals in the attached figures

[0112] 10...Grinding device; 11...Base; 11a...Grinding wheel guide; 11b...Spindle table guide; 12...Grinding wheel; 12a...Grinding wheel rotary motor; 13...Grinding wheel holder; 14...Spindle box; 14a...Spindle rotary motor; 15...Tailstock; 16...Spindle table; 17...Controller; 20...In-machine measuring device; 21...Probe; 22...Finger part; 23...Axial movement device; 24...Axial movement control unit; 25...High-frequency component measuring device; 30...Output device; 31...Basic data acquisition unit; 32 ...First data analysis and processing unit; 321...Low-frequency component extraction unit; 322...Helical low-frequency waveform generation unit; 323...Low-frequency intercentric relative vibration waveform generation unit; 324...Workpiece reference radius calculation unit; 33...Second data analysis and processing unit; 331...Helical high-frequency component extraction unit; 332...One-section high-frequency component extraction unit; 333...Helical high-frequency waveform generation unit; 334...High-frequency intercentric relative vibration waveform generation unit; 335...Grinding wheel surface unevenness calculation unit; 34...Output processing unit; 341...Shape analysis output unit; 342...Machining status output unit; 3 43...Mechanical status output unit; 344...Graphic generation output unit; 40...Image output device; A1, A2, A3, A4...Analysis results; C...Number of spirals; K1...First measurement data; K2...Second measurement data; D1...First basic data; D11...Low-frequency component; D12...High-frequency component of the spiral; D2...Second basic data; D21...Low-frequency component (first analysis result); D22...High-frequency component (second analysis result); D221...High-frequency component of a cross section; LDV...Low-frequency intercardiac relative vibration waveform (first analysis result); HDV ...High-frequency intercentric relative vibration waveform (second analytical result); SLW...helical low-frequency waveform (first analytical result); SHW...helical high-frequency waveform (second analytical result); M1, M2, M3, M4, M5...Figure; O...rotation center; R...workpiece reference radius (first analytical result); P...grinding wheel surface unevenness (second analytical result); S...surface characteristics; S1...surface characteristics (caused by the grinding wheel); S2...surface characteristics (caused by intercentric relative vibration); S11, S12, S21, S22...surface characteristics; H...in-machine measurement system; W...workpiece.

Claims

1. An in-machine measurement system, wherein, The in-machine measurement system includes: An in-machine measuring device is installed in a grinding device equipped with a grinding wheel. The in-machine measuring device measures the surface condition of a workpiece after grinding with the grinding wheel and outputs measurement data representing the surface condition of the workpiece. and The output device uses the measurement data obtained by the on-machine measuring device through relative movement of the measurement position on the surface of the workpiece relative to the workpiece to perform multiple analyses related to the machining quality of the workpiece after grinding by the grinding device, and outputs multiple analysis results. The in-machine measuring device measures the surface state of the workpiece by moving the measuring position of the workpiece surface in a spiral motion in the circumferential and axial directions of the workpiece, and outputs first measuring data as the measuring data. The in-machine measuring device measures the surface condition of the workpiece by moving the measuring position circumferentially from the same position along the axial direction of the workpiece, and outputs second measuring data as the measuring data. The output device uses the first low-frequency component and the first high-frequency component in the frequency components of the first measured data, as well as the second low-frequency component and the second high-frequency component in the frequency components of the second measured data, to perform the multiple analyses and output multiple analysis results.

2. The in-machine measurement system according to claim 1, wherein, The output device has: The first data parsing and processing unit calculates multiple first parsing results by using the parsing and processing of the first low-frequency component and the second low-frequency component; The second data parsing and processing unit calculates multiple second parsing results by using the parsing and processing of the first high-frequency component and the second high-frequency component; as well as The output processing unit outputs a plurality of the parsing results using at least one of the first parsing result and the second parsing result.

3. The in-system measurement system according to claim 1 or 2, wherein, The multiple analytical results include: machining accuracy related to the grinding of the workpiece by the grinding device, and mechanical condition related to the grinding of the grinding device.

4. The in-machine measurement system according to claim 1, wherein, The in-machine measuring device outputs the measuring data for each grinding operation of the workpiece performed by the grinding device.

5. The in-system measurement system according to claim 1 or 2, wherein, The in-machine measurement device outputs the measurement data as time series data.

6. The in-system measurement system according to claim 1 or 2, wherein, The in-machine measuring device includes a dimensional device for measuring the outer diameter of the workpiece in the grinding apparatus.

7. The in-system measurement system according to claim 6, wherein, The in-machine measuring device includes the dimensional fixing device and the high-frequency component measuring device. The high-frequency component measuring device is assembled with the dimensional fixing device and measures the first high-frequency component and the second high-frequency component in the frequency composition of the surface state of the workpiece. The dimensional device is used to measure the first low-frequency component and the second low-frequency component in the frequency composition of the surface state of the workpiece. The high-frequency component measuring device is used to measure the first high-frequency component and the second high-frequency component in the frequency components of the surface state of the workpiece.

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