JP2024002285A - Surface property estimation device and grinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface property estimation device that can improve accuracy in estimating a surface property, by mitigating effect of noise due to a gain unstable frequency band with a natural vibration property.

SOLUTION: A calculation processing device 20 of a surface property estimation device 2 is provided with: a signal data obtaining part 21 that obtains first spiral data D1 on an acceleration sensor 32 of a sizing instrument 3; an evaluation information storage part 23 that stores evaluation information I in which a gain stable frequency band K0 and a gain unstable frequency band K1 are set in a natural vibration property K of the acceleration sensor 32; a rotation speed setting part 25 that sets a measurement-time rotation speed Vw2 of the work-piece W, on the basis of a relation between a processing-time rotation speed Vt1 of a grinding wheel 12 and a processing-time rotation speed Vw1 of the work-piece W; and a surface property estimation part 22 that estimates, as a surface property S, a concave-convex surface state of a ground peripheral surface W1 of the work-piece W, on the basis of the first spiral data D1 obtained by the signal data obtaining part 21 when the work-piece W is rotated at the measurement-time rotation speed Vw2, at the time of measurement.

SELECTED DRAWING: Figure 6

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a surface texture estimating device and a grinding machine.

The surface texture estimating device is used to estimate (measure) surface texture such as unevenness on the surface of a workpiece rotatably supported by a grinding machine. The surface of the grinding wheel of a grinding machine has irregularities formed by a large number of abrasive grains, and during grinding, the irregularities caused by the abrasive grains are reflected on the surface of the workpiece. In the grinding machine, the surface texture formed on the surface of the workpiece depends on the processing conditions such as the state of the abrasive grains in the grinding wheel, the rotational speed of the grinding wheel, the rotational speed of the workpiece, and the shape of the workpiece. changes. A surface texture estimating device uses a sizing device with a sensor to measure the irregularities that occur on the surface of a workpiece in the circumferential and axial directions, and uses the measurement results of these irregularities to estimate the surface of the workpiece. The surface texture of the surface is estimated.

For example, in the surface texture estimation system of Patent Document 1, when the measurement position on the surface of the workpiece is moved spirally in the circumferential direction and the axial direction, a sensor detects irregularities on the surface of the workpiece. It is described that the surface texture of the surface of a workpiece is generated based on time series data related to The time-series data is acquired corresponding to the helical position at each predetermined angle with respect to the rotation axis of the workpiece, and based on the time-series data, the circumference at different angles of the workpiece and at different axial positions of the workpiece is Directional vibration is generated. Then, the circumferential chatter is regarded as a plurality of circumferential chatters at the same angle of the workpiece, and a planar chatter is generated in which the plurality of circumferential chatters are arranged in parallel in the axial direction.

JP 2021-79534 Publication

Sensors constituting sizing devices and the like have natural vibration characteristics as frequency response characteristics due to the influence of vibrations generated in various parts of the grinding machine. This natural vibration characteristic affects the measurement of irregularities on the surface of the workpiece by a sizing device or the like as noise, and becomes an error factor in estimating the surface texture of the surface of the workpiece. The surface texture estimation system of Patent Document 1 also does not take this natural vibration characteristic into consideration, and there is a risk that an error may occur in the generation (estimation) of the surface texture. Therefore, in order to improve the accuracy of estimating the surface texture of the surface of the workpiece by the surface texture estimating device, further efforts are required.

The present invention has been made in view of such problems, and the present invention is a surface texture estimating device and a grinding machine that can improve the estimation accuracy of surface texture by alleviating the influence of noise due to the unstable gain frequency band of natural vibration characteristics. This is what we are trying to provide.

One aspect of the present invention is
A surface texture estimation device for estimating the surface texture of a ground peripheral surface of a workpiece that has been ground by a grinding wheel in a grinding machine,
a sizing device that is provided on the grinding machine and measures the diameter of the peripheral surface to be ground while the workpiece is being ground while being rotated;
The grinding of the workpiece due to the grinding wheel to which the uneven surface of the grinding wheel has been transferred is based on signal data output from a sensor provided in the sizing device during measurement after the grinding process of the workpiece. an arithmetic processing device that estimates an uneven surface state of the peripheral surface as the surface texture;
Equipped with
The arithmetic processing device is
A signal that acquires the signal data when the sizing device and the workpiece are relatively moved in the axial direction of the workpiece while rotating the workpiece, corresponding to the uneven surface state of the grinding peripheral surface. a data acquisition section;
When a vibration with a changed frequency is applied to the sizing device as an input, in the natural vibration characteristic as a frequency response characteristic of the output data output from the sensor, the variation in the gain of the natural vibration characteristic is within a predetermined value. Stores evaluation information in which a gain stable frequency band included in the gain stable frequency band and a gain unstable frequency band whose frequency is lower than the gain stable frequency band and whose variation in the gain of the natural vibration characteristic exceeds the predetermined value are set. an evaluation information storage unit for
a machining condition acquisition unit that acquires a machining rotational speed Vt1 of the grinding wheel and a machining rotational speed Vw1 of the workpiece during grinding of the workpiece by the grinding wheel;
Based on the relationship between the machining rotation speed Vt1 of the grinding wheel and the machining rotation speed Vw1 of the workpiece, when the measurement rotation speed Vw2 of the workpiece at the time of measurement is assumed, the signal data includes: rotation for setting the rotational speed Vw2 of the workpiece during measurement so that at least two selected frequencies of a fundamental frequency component to be measured and a harmonic component of the fundamental frequency component are included in the gain stable frequency band; a speed setting section;
Based on the signal data acquired by the signal data acquisition unit when the workpiece is rotated at the measurement rotation speed Vw2 during the measurement, the uneven surface state of the grinding peripheral surface is determined based on the surface texture. a surface texture estimating unit that estimates as;
A surface texture estimating device is provided.

Another aspect of the present invention is a grinding machine including the surface texture estimating device according to the above-described one aspect.

In the surface texture estimating device of the above aspect, evaluation information of the natural vibration characteristics by the sensor is stored, and the measurement of the workpiece is performed with respect to the rotational speed (rotation speed) Vw1 during machining of the workpiece, taking the natural vibration characteristics into consideration. By intentionally changing the rotational speed (number of rotations) Vw2, the influence of the natural vibration characteristics on the estimation of the surface texture is alleviated. Specifically, in the evaluation information in the evaluation information storage section, a gain stable frequency band and a gain unstable frequency band are set for the natural vibration characteristics.

Then, in the rotational speed setting section, when the rotational speed Vw2 of the workpiece at the time of measurement is assumed based on the relationship between the rotational speed Vt1 of the grinding wheel during machining and the rotational speed Vw1 of the workpiece during machining, The rotational speed Vw2 of the workpiece during measurement is set so that at least two selected frequencies of the fundamental frequency component and the harmonic component to be included in the signal data of the signal data acquisition section are included in the gain stable frequency band. .

By setting the rotational speed Vw2 of the workpiece during measurement in this way, it is possible to prevent the influence of noise due to the unstable gain frequency band of the natural vibration characteristics from occurring on the signal data acquired by the signal data acquisition unit during measurement. It can be done. Then, by reducing the error factor, it is possible to improve the accuracy of estimating the surface texture by the surface texture estimating section.

Therefore, according to the surface texture estimating device of the above aspect, it is possible to improve the estimation accuracy of the surface texture by excluding the influence of noise due to the unstable gain frequency band of the natural vibration characteristics.

According to the grinding machine of the other aspect, the same effects as those of the surface texture estimating device of the above-described one aspect are exhibited.

FIG. 1 is an explanatory diagram showing a grinding machine including a surface texture estimating device according to an embodiment. FIG. 2 is an explanatory diagram showing a surface texture estimating device during measurement after grinding a workpiece according to an embodiment. FIG. 1 is an explanatory diagram showing a surface texture estimating device during grinding of a workpiece according to an embodiment. 1 is a flowchart showing a grinding process of a grinder according to an embodiment. FIG. 2 is an explanatory diagram showing the surface texture of the ground peripheral surface of a workpiece ground by a grinding machine according to the embodiment. FIG. 1 is an explanatory diagram showing the configuration of a surface texture estimating device according to an embodiment. FIG. 7 is an explanatory diagram showing divided data of first spiral data by an acceleration sensor according to the embodiment. FIG. 4 is an explanatory diagram showing phase matching data of first spiral data by an acceleration sensor according to the embodiment. FIG. 7 is an explanatory diagram showing a chatter map based on first spiral data obtained by an acceleration sensor according to the embodiment. FIG. 7 is an explanatory diagram showing a radius map based on second spiral data and rotation data obtained by a displacement sensor according to the embodiment. FIG. 4 is an explanatory diagram showing a surface texture map in which a chatter map and a radius map are combined according to the embodiment. 3 is a graph showing natural vibration characteristics of an acceleration sensor according to an embodiment. 7 is a graph showing Fourier transform data after fast Fourier transform of first spiral data obtained by an acceleration sensor according to the embodiment. 7 is a graph showing Fourier transform data after fast Fourier transform of first spiral data obtained by an acceleration sensor according to the embodiment.

A preferred embodiment of the above-described surface texture estimating device and a grinding machine equipped with the surface texture estimating device will be described with reference to the drawings.
(Embodiment)

1. Configuration of Grinding Machine 1 The configuration of the grinding machine 1 will be explained. As shown in FIG. 1, the grinding machine 1 includes a surface texture estimating device 2. The surface texture estimation device 2 is used as an analysis device for the grinding state of the grinding machine 1. In particular, the surface texture estimating device 2 estimates the surface texture S of the ground peripheral surface W1 of the workpiece W that has been ground by the grinding wheel 12 in the grinding machine 1. The grinding machine 1 includes an image output device 4 that outputs the surface texture S of the grinding peripheral surface W1 of the workpiece W estimated by the surface texture estimation device 2 as a surface texture map M as a mapped image.

The grinding machine 1 performs a grinding process on the grinding peripheral surface W1 of the workpiece W by rotating the workpiece W and the grinding wheel 12 and moving the workpiece W and the grinding wheel 12 relative to each other. The grinding machine 1 can be applied to a table traverse type grinder that traverses the workpiece W, or can be applied to a grindstone traverse type grinder that traverses the grindstone head 13 that supports the grinding wheel 12. Below, a table traverse type grinder will be described as an example of the grinder 1.

The grinding machine 1 includes a bed 11, a grinding wheel 12, a grinding wheel head 13, a headstock 14, a tailstock 15, a spindle table 16, a control device 10, and a surface texture estimating device 2. The workpiece W is supported at both ends in the axial direction by a headstock 14 and a tailstock 15, and is driven by the headstock 14 to rotate. The shape of the workpiece W is not particularly limited, and may be a columnar shape, a cylindrical shape, or the like. As shown in FIG. 2, the grinding peripheral surface W1 of the workpiece W may be not only the outer peripheral surface of the cylindrical or cylindrical workpiece W, but also the inner peripheral surface of the cylindrical workpiece W.

In this embodiment, the case where the workpiece W is cylindrical is illustrated. The grinding machine 1 brings a grinding wheel 12 into contact with an outer circumferential surface of a rotating workpiece W as a grinding circumferential surface W1, and uses the grinding wheel 12 to grind the outer circumferential surface of the workpiece W.

Here, the direction parallel to the axial direction of the workpiece W supported by the headstock 14 and the tailstock 15 is called the Z-axis direction, and the grinding wheel 12 is perpendicular to the Z-axis direction with respect to the workpiece W. The direction in which they approach is called the X-axis direction. In each figure, the Z-axis direction is indicated by the symbol Z, and the X-axis direction is indicated by the symbol X. The grinding wheel 12 is supported by a grinding wheel head 13 in a state where it can rotate around an axis parallel to the Z-axis direction. A whetstone head guide 11a is provided on the bed 11, and the whetstone 13 is supported by the whetstone head guide 11a so as to be movable in the X-axis direction. (not shown) in the X-axis direction.

The grinding wheel 12 is driven and rotated by a grinding wheel rotation motor 12a of a grinding wheel head 13, which is controlled by the control device 10. The grinding wheel 12 approaches the grinding circumferential surface W1 of the workpiece W by moving the grindstone head 13 in the X-axis direction, and grinds the grinding circumferential surface W1 of the workpiece W.

The spindle table 16 is supported movably in the Z-axis direction by a spindle table guide portion 11b provided on the bed 11, and is moved in the Z-axis direction by a drive source (not shown) controlled by the control device 10. do. The headstock 14 and the tailstock 15 are arranged facing each other on the spindle table 16. The workpiece W is driven and rotated by a spindle rotation motor 14a of the headstock 14, which is controlled by the control device 10.

2. Overview of surface texture estimating device 2 An overview of the surface texture estimating device 2 will be described. FIG. 2 shows the surface texture estimating device 2 during measurement after grinding the workpiece W, and FIG. shows. As shown in FIGS. 2 and 3, the surface texture estimating device 2 estimates the surface texture S of the ground peripheral surface W1 of the workpiece W that has been ground by the grinding wheel 12 of the grinding machine 1.

The surface texture estimating device 2 includes a sizing device 3 provided with an acceleration sensor 32 as a sensor, and an arithmetic processing device 20. The sizing device 3 is provided on the grinding machine 1 and measures the diameter of the grinding peripheral surface W1 of the workpiece W while the workpiece W is being ground while being rotated. At the time of measurement after grinding the workpiece W, the arithmetic processing unit 20 controls the grinding wheel 12 to which the uneven surface of the grinding wheel 12 has been transferred, based on the signal data output from the acceleration sensor 32 of the sizing device 3. The resulting uneven surface state of the grinding peripheral surface W1 of the workpiece W is estimated as the surface texture S.

3. Configuration of sizing device 3 of surface texture estimating device 2 Next, the sizing device 3 will be explained. In this embodiment, as shown in FIG. 2, the outer circumferential surface of the cylindrical workpiece W as the grinding circumferential surface W1 is ground, and the sizing device 3 is used as an outer diameter measuring device to measure the outer circumferential surface of the workpiece W. Measure the outer diameter. The sizing device 3 may measure the inner diameter of the inner circumferential surface of the workpiece W as the ground circumferential surface W1. The diameter of the grinding peripheral surface W1 of the workpiece W measured by the sizing device 3 is used for switching the grinding process. However, in this embodiment, the sizing device 3 is also used for estimating the surface texture S of the ground peripheral surface W1 of the workpiece W by the surface texture estimating device 2.

The sizing device 3 includes a pair of contact members 31 that come into contact with the grinding circumferential surface W1 of the workpiece W and are displaced in accordance with the uneven surface condition of the grinding circumferential surface W1, and an acceleration sensor disposed on one of the contact members 31. 32. By using the acceleration sensor 32, it becomes easy to measure the uneven surface of the high frequency component on the grinding peripheral surface W1 of the workpiece W.

A contactor 33 that contacts the grinding peripheral surface W1 of the workpiece W is provided at the tip of the pair of contact members 31. The contactor 33 contacts the grinding circumferential surface W1 of the workpiece W at two points sandwiching the rotation center O of the workpiece W, and is displaced following the uneven surface formed on the grinding circumferential surface W1. The displacement of the contactor 33 is measured by a displacement sensor 34. The displacement sensor 34 uses, for example, a differential transformer that converts mechanical linear motion into an electrical signal as a displacement amount.

The sizing device 3 measures the outer diameter of the grinding peripheral surface W1 of the workpiece W by converting the mechanical displacement of the displacement sensor 34 into signal data that is an electrical signal, and also measures the acceleration detected by the acceleration sensor 32. The uneven surface state of the ground peripheral surface W1 of the workpiece W is measured by converting it into displacement and signal data which is an electric signal. As shown in FIG. 1, the sizing device 3 is movable in the Z-axis direction parallel to the central axis of the workpiece W by an axial movement device 35 controlled by the control device 10.

The condition of the uneven surface of the ground circumferential surface W1 of the workpiece W is determined by the signal data of the displacement sensor 34 during measurement when rotating the workpiece W after grinding and measuring the condition of the uneven surface of the ground circumferential surface W1 of the workpiece W. The uneven surface is a low frequency component detected based on the signal data of the acceleration sensor 32, and the uneven surface is a high frequency component detected based on the signal data of the acceleration sensor 32. The low frequency component detected based on the signal data of the displacement sensor 34 is, for example, a frequency of 10 Hz or less, and the high frequency component detected based on the signal data of the acceleration sensor 32 is, for example, a frequency exceeding 10 Hz and below 2500 Hz. Detected as a frequency.

4. Grinding process of the grinding machine 1 Next, the grinding process of the grinding machine will be explained. As shown in FIG. 4, the grinding process is divided according to the feed speed of the grinding wheel 12 in the X-axis direction, and is divided into a rough grinding process St1, a fine grinding process St2, a fine grinding process St3, and a spark-out process St4. It will be done. The feed speed of the grinding wheel 12 in each process is as follows: rough 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 grinding step St2 and fine grinding step St3, the surface shape of the workpiece W is prepared while reducing the feed speed of the grinding wheel 12. In the final spark-out step St4, the surface of the workpiece W is finished, and the workpiece W is completed.

The diameter of the grinding peripheral surface W1 of the workpiece W measured by the sizing device 3 is used for switching the grinding process. In the control device 10 of the grinding machine 1, the diameter of the workpiece W at the time of switching between the rough grinding process St1 and the fine grinding process St2, the diameter of the workpiece W at the time of switching between the fine grinding process St2 and the fine grinding process St3, And the diameter of the workpiece W at the time of switching between the fine grinding process St3 and the spark-out process St4 is set. During the grinding process, when the diameter of the workpiece W measured by the sizing device 3 reaches the set diameter, the grinding process is switched by the control device 10 of the grinding machine 1.

Here, in the surface texture estimating device 2, it is preferable to estimate the surface texture S of the workpiece W after the spark-out step St4 in which grinding is completed. The surface texture estimating device 2 estimates the surface texture S of the workpiece W in an in-process. In-process is a period from when the workpiece W is ground until it is removed from the grinding machine 1, and includes the period after the spark-out step St4. The surface texture estimating device 2 of this embodiment maintains the rotational state of the workpiece W during grinding after the grinding of the workpiece W is completed, and appropriately increases the rotational speed as the measurement rotational speed Vw2 of the workpiece W. Estimate the surface texture S of the workpiece W.

5. Surface texture S of the grinding peripheral surface W1 of the workpiece W
Next, the surface texture S of the ground peripheral surface W1 of the workpiece W will be explained. As shown in FIG. 5, the surface texture S of the ground peripheral surface W1 of the workpiece W ground by the grinding machine 1 is formed due to various factors. In the present embodiment, the surface texture S refers to a surface texture resulting from the grinding wheel 12 to which an uneven surface as a surface condition of the grinding outer circumferential surface of the grinding wheel 12 is transferred.

The surface texture S of the grinding peripheral surface W1 caused by the grinding wheel 12 is separated into a surface texture S1 to which the uneven surface of the grinding wheel 12 is transferred, and a surface texture S2 due to variations in the reference radius in the circumferential direction C of the workpiece W. be done. The surface texture S is generated by combining (adding) the surface textures S1 and S2. Variations in the reference radius in the circumferential direction C of the workpiece W are expressed as roundness, etc., and are mainly caused by a shift in the distance between the center of the grinding wheel 12 and the center of the workpiece W during grinding. it is conceivable that.

6. Configuration of Processing Unit 20 of Surface Texture Estimating Device 2 Next, the processing unit 20 of the Surface Texture Estimating Device 2 will be described. As shown in FIG. 6, the arithmetic processing device 20 includes a signal data acquisition section 21, an evaluation information storage section 23, a machining condition acquisition section 24, a rotation speed setting section 25, a workpiece spindle drive section 26, and a surface texture estimation section 22. Be prepared.

In other words, when the signal data acquisition unit 21 moves the sizing device 3 and the workpiece W relative to each other in the Z-axis direction of the workpiece W while rotating the workpiece W, in other words, the signal data acquisition unit 21 detects that the contactor 33 of the sizing device 3 When the position of contact with the workpiece W is relatively moved spirally in the Z-axis direction, the signal data from the acceleration sensor 32 of the sizing device 3 and the signal data from the displacement sensor 34 of the sizing device 3 are It is acquired corresponding to the uneven surface state of the surface W1. The signal data from the acceleration sensor 32 is acquired as first spiral data D1 having a high frequency component, and the signal data from the displacement sensor 34 is acquired as second spiral data D2 having a low frequency component. Furthermore, when the relative position between the sizing device 3 and the workpiece W in the Z-axis direction is fixed and the workpiece W is rotated, the signal data acquisition unit 21 receives the signal data from the displacement sensor 34 as rotation data D3. get.

In FIG. 5, a state in which the first spiral data D1 and second spiral data D2 are measured by the sizing device 3 and a state in which the rotation data D3 is measured by the sizing device 3 are shown by broken lines. The first spiral data D1 and the second spiral data D2 are acquired simultaneously as data on a part of the ground circumferential surface W1 of the workpiece W in the Z-axis direction and a part in the circumferential direction C. A part of the first spiral data D1 in the circumferential direction C is extracted as a range in which the grinding wheel surface 121 of the grinding wheel 12 is transferred multiple times to the grinding peripheral surface W1 of the workpiece W. Grinding marks caused by each abrasive grain of the grinding wheel 12 repeatedly appear within a part of the circumferential direction C of the grinding peripheral surface W1. The first spiral data D1 from the acceleration sensor 32 is used to measure the uneven surface state of the ground peripheral surface W1 of the workpiece W.

The second spiral data D2 from the displacement sensor 34 is used to measure the difference in radius of the workpiece W in the Z-axis direction. Originally, the difference in radius of the workpiece W in the Z-axis direction can be measured by relatively moving the sizing device 3 in the Z-axis direction of the workpiece W. However, the second spiral data D2 is acquired when the contactor 33 moves relative to the acceleration sensor 32 in a spiral manner simultaneously in the circumferential direction C and the Z-axis direction. Therefore, from the change in the radius of the grinding peripheral surface W1 of the workpiece W in the Z-axis direction and the change in the radius of the grinding peripheral surface W1 of the workpiece W in the circumferential direction C according to the second spiral data D2, the workpiece W according to the rotation data D3 By excluding the change in the radius of the ground circumferential surface W1 of the workpiece W in the circumferential direction C, the change in the radius of the ground circumferential surface W1 of the workpiece W in the Z-axis direction is obtained.

The rotation data D3 is acquired as data for the entire circumference in the circumferential direction C at the same position in the Z-axis direction that overlaps a part of the range in the Z-axis direction of the first spiral data D1 and the second spiral data D2. It is considered that the change in the radius of the ground circumferential surface W1 of the workpiece W in the circumferential direction C, which is indicated by the roundness or the like, is maintained in the same state in the Z-axis direction. Therefore, the rotation data D3 may be acquired at one position in the Z-axis direction. However, in order to improve accuracy, the rotation data D3 may be acquired at a plurality of positions in the Z-axis direction within the range of the first spiral data D1 and the second spiral data D2 in the Z-axis direction.

As shown in FIG. 6, the surface texture estimation unit 22 calculates the grinding circumference based on the signal data acquired by the signal data acquisition unit 21 when the workpiece W is rotated at the measurement rotation speed Vw2 during measurement. The uneven surface state of the surface W1 is estimated as the surface texture S. The surface texture estimation unit 22 performs signal processing on the first spiral data D1, the second spiral data D2, and the rotation data D3, estimates the surface texture S of the ground peripheral surface W1 of the workpiece W, and colorizes the surface texture S. A surface texture map M that is visually expressed based on the difference between the two is created. The surface texture map M includes a chatter map M1 showing the surface texture S1 of the grinding circumferential surface W1 caused by the uneven surface of the grinding wheel 12, and a chatter map M1 showing the surface texture S1 of the grinding circumferential surface W1 caused by errors in the roundness, radius, etc. of the grinding circumferential surface W1. It is created by combining the radius map M2 indicating the surface texture S2.

The chatter map M1 is created by performing signal processing on the first spiral data D1, which is signal data from the acceleration sensor 32. This signal processing is performed by each step of gain correction processing 221a, division processing 222, high frequency component analysis 223a, and phase matching processing 224. In the gain correction processing 221a, it is taken into consideration that the acceleration sensor 32 has an input/output characteristic that attenuates the output signal for an input signal exceeding a specific frequency, and the frequency is adjusted so that the variation in the output signal of the acceleration sensor 32 is reduced. Each output signal is corrected.

As shown in FIG. 7, in the dividing process 222, the first spiral data D1 about the grinding peripheral surface W1 of the workpiece W is divided into two parts at each position in the Z-axis direction set at predetermined intervals in the Z-axis direction. is divided into a plurality of divided data D11 as data for each position in the circumferential direction C set at predetermined intervals in the circumferential direction C. In the high frequency component analysis 223a, fast Fourier transform (FFT) is performed on each divided data D11. Regarding the uneven surface state of the grinding peripheral surface W1 in which abrasive grain marks are repeatedly formed by each abrasive grain of the grinding wheel 12, the formation state of each abrasive grain mark is expressed by a high frequency component expressed by frequency (or period) and amplitude. is extracted as Fourier transform data.

Thereafter, a specific high frequency component is extracted so as to remove noise components in the Fourier transform data of the high frequency component, and an inverse fast Fourier transform (inverse FFT) is performed on the extracted high frequency component. Thereby, noise components in each divided data D11 are removed. The noise component includes noise due to mechanical vibration and the like.

In this embodiment, as will be described later, by adjusting the rotational speed Vw2 of the workpiece W during measurement in an increasing direction, the number of repeated appearances of each abrasive grain mark on the grinding peripheral surface W1 is increased, and the high frequency component analysis At 223a, the frequency when the first spiral data D1 is Fourier transformed is adjusted in an increasing direction.

As shown in FIG. 8, in the phase matching process 224, the divided data D11 after noise component removal set at each position in the Z-axis direction and shifted at each position in the circumferential direction C is Phase matching is performed so as to be located at the site, and phase matching data D12 is created. When this phase matching is performed, the phase in the circumferential direction C is finely adjusted so that the uneven surface state of the ground circumferential surface W1 in the phase matching data D12 does not become intermittent in the Z-axis direction. In this way, as shown in FIG. 9, a chatter map M1 is created for the first spiral data D1 obtained by the acceleration sensor 32.

The radius map M2 is created by performing signal processing on the second spiral data D2 and rotation data D3, which are signal data from the displacement sensor 34 of the sizing device 3. This signal processing is performed separately into steps of gain correction processing 221b and low frequency component analysis 223b for the second spiral data D2, and steps of gain correction processing 221c and roundness analysis 225 for the rotation data D3. Then, as a roundness removal process 226, the second spiral data D2 after the low frequency component analysis 223b and the rotation data D3 after the roundness analysis 225 are used. , a change in radius in the Z-axis direction on the grinding peripheral surface W1 of the workpiece W is acquired.

In the gain correction processing 221b, 221c of the second spiral data D2 and rotation data D3, it is taken into consideration that the displacement sensor 34 has an input/output characteristic that attenuates an output signal for an input signal exceeding a specific frequency. The output signal for each frequency is corrected so that the variation in the output signal is reduced.

In the low frequency component analysis 223b of the second spiral data D2, fast Fourier transform (FFT) is performed on the second spiral data D2. Then, changes in the radius of the grinding peripheral surface W1 of the workpiece W in the Z-axis direction and the circumferential direction C are extracted as Fourier transform data of low frequency components expressed by frequency (or period) and amplitude.

Thereafter, a specific low frequency component is extracted so as to remove noise components in the Fourier transform data of the low frequency component, and an inverse fast Fourier transform (inverse FFT) is performed on the extracted low frequency component. Thereby, noise components in the second spiral data D2 are removed. The noise component includes noise due to mechanical vibration and the like. The second spiral data D2 also includes a change in the radius of the grinding peripheral surface W1 of the workpiece W in the Z-axis direction.

In the roundness analysis 225 of the rotation data D3, it is analyzed how much unevenness is caused by roundness errors in the uneven surface state of the ground peripheral surface W1 of the workpiece W. Then, in the roundness removal process 226, the rotation data D3 after the roundness analysis 225 is collated with the second spiral data D2 after the low frequency component analysis 223b, and the second spiral The influence of unevenness in the circumferential direction C and the Z-axis direction and the influence of unevenness due to errors in roundness are excluded from the data D2. Then, radius data indicating the difference in radius for each position in the Z-axis direction is acquired, and as shown in FIG. 10, a radius map M2 is created based on the radius data.

Thereafter, as shown in FIG. 11, the chatter map M1 and the radius map M2 are combined to create a surface texture map M. In the surface texture map M, the uneven surface condition of the ground circumferential surface W1 of the workpiece W, which reflects the difference in radius at each position in the Z-axis direction, is visualized by color coding or the like. In FIG. 11, the width of one rotation of the grinding wheel 12 is shown in the circumferential direction C of the grinding peripheral surface W1 of the workpiece W.

7. Adjustment of the measurement rotation speed Vw2 of the workpiece W Next, adjustment of the measurement rotation speed Vw2 of the workpiece W will be described. The surface texture estimating unit 22 of this embodiment adjusts the rotational speed Vw2 of the workpiece W at the time of measurement in consideration of the natural vibration characteristic K that the acceleration sensor 32 has, and adjusts the rotational speed Vw2 of the workpiece W at the time of measurement, and A component analysis 223a is performed. Specifically, as shown in FIG. The measuring rotational speed Vw2 of the workpiece W when measuring the uneven surface state of the surface W1 is adjusted to reduce the influence of noise due to the natural vibration characteristic K of the acceleration sensor 32 on the estimation of the surface texture S.

As shown in FIG. 12, the evaluation information storage unit 23 stores the frequency response characteristics of output data output from the acceleration sensor 32 when vibrations with varying frequencies are input to the acceleration sensor 32 of the sizing device 3. In the natural vibration characteristic K, there is a gain stable frequency band K0 in which the variation ΔG of the gain G of the natural vibration characteristic K is within a predetermined value, and a gain stable frequency band K0 whose frequency is lower than the gain stable frequency band K0 and the gain of the natural vibration characteristic K. Evaluation information I in which a gain unstable frequency band K1 in which G variation ΔG exceeds a predetermined value is set is stored.

In the gain unstable frequency band K1, not only the gain G indicating the input/output ratio of the acceleration sensor 32 is significantly larger than 1, but also the variation ΔG in the gain G is large. In the high frequency component analysis 223a of the surface texture estimation unit 22, it is preferable not to use the first spiral data D1 of frequencies included in the gain unstable frequency band K1.

In the present embodiment, the evaluation information I in the evaluation information storage unit 23 includes, in addition to the gain stable frequency band K0 and the gain unstable frequency band K1, a frequency higher than the gain stable frequency band K0 and an acceleration sensor. An anti-resonance frequency band K2 in which the gain G of the natural vibration characteristic K fluctuates up and down due to the anti-resonance characteristic of 32 is set, in which gain compensation cannot be performed. When the gain G fluctuates up and down, it refers to a state in which a case where the gain G fluctuates more than 1 and a case where the gain G fluctuates less than 1 occur successively when the frequency changes. The term "gain compensation impossible" refers to a state in which it is difficult to correct the gain G as the input/output ratio of the acceleration sensor 32 to be close to 1. In the high frequency component analysis 223a of the surface texture estimating section 22, it is preferable not to use the first spiral data D1 of frequencies included in the anti-resonant frequency band K2.

In order to obtain the natural vibration characteristic K of the acceleration sensor 32, before the surface texture estimating device 2 and the grinding machine 1 are operated, the vibration device 5 shown in FIG. A vibration is applied to the acceleration sensor 32, and a change in the output from the acceleration sensor 32 is measured. Then, the degree of increase/decrease in the amplitude of the output of the acceleration sensor 32 with respect to the amplitude of the vibration input to the acceleration sensor 32 by the vibration device 5 is obtained as a frequency response characteristic for the gain G of the acceleration sensor 32. In the frequency response characteristic for this gain G, the natural vibration characteristic K is determined from the gain unstable frequency band K1, the gain unstable frequency band K1, and the gain A stable frequency band K0 and an anti-resonant frequency band K2 are set.

The gain G is 1 when the amplitude of the output is the same as the amplitude of the input, a value larger than 1 when the amplitude of the output becomes large, and a value smaller than 1 when the amplitude of the output becomes small. The variation ΔG in the gain G indicates the width of the variation in the gain G within a predetermined frequency range.

The gain unstable frequency band K1 is set as a frequency range in which the gain G approaches 1 from a large value near 100, and in which the variation ΔG exceeds a predetermined value. The gain stable frequency band K0 is set as a frequency range in which the gain G is close to 1, and in which the variation ΔG is within a predetermined value. The anti-resonant frequency band K2 is set as a frequency range in which the gain G swings greatly between greater than 1 and less than 1. The predetermined value of the variation ΔG is determined by focusing on the allowable range of variation in the gain G within a predetermined frequency range. The permissible range of variation in gain G is set as a range of numerical values such as ±1.2 times the variation in gain G, for example.

In the present embodiment, the stable gain frequency band K0 of the evaluation information I in the evaluation information storage section 23 includes a resonant frequency band K3 in which the gain G of the natural vibration characteristic K fluctuates up and down due to the resonance characteristics of the acceleration sensor 32, where the gain can be compensated. It is set. In the resonance frequency band K3, while the gain G fluctuates up and down, the variation ΔG of the gain G is within a predetermined value. The resonance frequency band K3 is a frequency band that can be corrected so that the gain G as the input/output ratio of the acceleration sensor 32 becomes close to 1, and the first spiral data D1 of frequencies included in the resonance frequency band K3 is , may be used in the high frequency component analysis 223a of the surface texture estimating section 22. However, the first spiral data D1 having a frequency included in the resonance frequency band K3 may not be used in order to simplify the correction of the gain G.

As shown in FIG. 6, the machining condition acquisition unit 24 acquires the machining rotational speed Vt1 of the grinding wheel 12 and the machining rotational speed Vw1 of the workpiece W when the grinding wheel 12 grinds the workpiece W. The rotational speed of the grinding wheel 12 is faster than the rotational speed of the workpiece W, and the rotational speed Vt1 of the grinding wheel 12 during machining is greater than the rotational speed Vw1 of the workpiece W during machining.

As shown in FIGS. 6 and 12, the rotational speed setting unit 25 is configured based on the relationship between the rotational speed Vt1 of the grinding wheel 12 during machining and the rotational speed Vw1 of the workpiece W during machining, which is acquired by the machining condition acquisition unit 24. Assuming the measurement rotation speed Vw2 of the workpiece W at the time of measurement, the fundamental frequency component F1 included in the first spiral data D1, which is the signal data of the acceleration sensor 32, and the fundamental frequency component F1. The rotational speed Vw2 of the workpiece W at the time of measurement is set so that at least two selected frequencies Fs of the harmonic components F2 are included in the gain stable frequency band K0.

The fundamental frequency component F1 is generated by the sizing device when the workpiece W is rotated at the rotational speed Vw2 at the time of measurement due to the unevenness as grinding marks caused by a large number of abrasive grains of the grinding wheel 12 on the grinding peripheral surface W1 of the workpiece W. represents the frequency repeatedly detected by the acceleration sensor 32 of No. 3. The harmonic component F2 is expressed as a component that is an integral multiple of the fundamental frequency component F1, and is expressed as a frequency that is a second-order component or higher when the fundamental frequency component F1 is a first-order component. The harmonic component F2 is generated due to the characteristics of the acceleration sensor 32.

The high-frequency component analysis 223a of the surface texture estimating unit 22 calculates the measurement rotational speed Vw2 of the workpiece W at the time of measurement in which the uneven surface state of the ground peripheral surface W1 of the workpiece W is measured by the sizing device 3. The rotational speed during machining is set to be faster than Vw1. By increasing the rotation speed Vw2 of the workpiece W during measurement, the frequency of the frequency component in the divided data D11 of the first spiral data D1 by the acceleration sensor 32, which is used for the high frequency component analysis 223a, is shifted to a higher frequency side. In other words, by increasing the measurement rotational speed Vw2 of the workpiece W, when measuring the uneven surface state of the grinding peripheral surface W1 of the workpiece W with the acceleration sensor 32, The period at which the unevenness of the abrasive grain marks is repeatedly measured becomes shorter.

Further, in the present embodiment, the rotation speed setting unit 25 sets the at least two selected frequencies Fs to be included in the gain stable frequency band K0, excluding the gain unstable frequency band K1 and the anti-resonance frequency band K2. The rotational speed Vw2 of the workpiece W during measurement is set. With this configuration, at least two selected frequencies Fs are also removed from the anti-resonant frequency band K2, improving the accuracy of the high frequency component analysis 223a.

FIG. 13 shows Fourier transform data of a high frequency component expressed by the relationship between frequency and amplitude, which is obtained by performing fast Laplace transform on the first spiral data D1 in the high frequency component analysis 223a of the surface texture estimation unit 22. show. FIG. 13 shows four selected frequencies Fs: a harmonic component F21 as a second-order component, a harmonic component F22 as a third-order component, a harmonic component F23 as a fourth-order component, and a harmonic component as a fifth-order component. A state in which component F24 is included in gain stable frequency band K0 including resonance frequency band K3 is shown. If the selection frequency Fs may be included in the resonance frequency band K3, selection of the selection frequency Fs is relatively easy.

Furthermore, in the present embodiment, the rotation speed setting unit 25 sets the at least two selected frequencies Fs to a gain stable frequency band K0 excluding the gain unstable frequency band K1 and the anti-resonant frequency band K2 and excluding the resonant frequency band K3. The rotational speed Vw2 of the workpiece W at the time of measurement is set so that it is included in . With this configuration, at least two selected frequencies Fs are also excluded from the resonance frequency band K3, and the accuracy of the high frequency component analysis 223a is further improved.

Similar to FIG. 13, FIG. 14 shows a high frequency signal expressed by the relationship between frequency and amplitude obtained by performing fast Laplace transform on the first spiral data D1 in the high frequency component analysis 223a of the surface texture estimation unit 22. Shows the Fourier transform data of the components. In FIG. 14, three selected frequencies Fs, a harmonic component F21 as a second-order component, a harmonic component F22 as a third-order component, and a harmonic component F24 as a fifth-order component, are shown except for the resonance frequency band K3. This shows a state included in the stable gain frequency band K0.

The high-frequency component analysis 223a of the surface texture estimating unit 22 is performed using signal data from the acceleration sensor 32, which is acquired by the signal data acquisition unit 21 when the workpiece W is rotated at the measurement rotation speed Vw2 during measurement. 1. Based on the spiral data D1, a plurality of calculation frequencies Fc in a predetermined range each including the selected frequency Fs are extracted, and based on the amplitudes of the plurality of calculation frequencies Fc, the uneven surface state of the grinding peripheral surface W1 is determined. is estimated as the surface texture S.

As shown in FIGS. 13 and 14, in the high frequency component analysis 223a of this embodiment, a plurality of calculation frequencies Fc in a predetermined range are calculated for the divided data D11 of the first spiral data D1 that has been subjected to fast Fourier transform. Extracted. The calculation frequency Fc is extracted as a frequency range having a predetermined width for at least two selected frequencies Fs of the fundamental frequency component F1 and the harmonic component F2 which is an integral multiple of the fundamental frequency component F1. The calculation frequency Fc may be extracted, for example, by setting a predetermined width around the frequency of the fundamental frequency component F1 or the harmonic component F2 and setting a predetermined width on the high frequency side and the low frequency side.

Note that a part of the calculation frequency Fc as a frequency range having a predetermined width may be included in the resonance frequency band K3. Further, the entire calculation frequency Fc as a frequency range having a predetermined width may not be included in the resonance frequency band K3. Further, it is preferable that the gain unstable frequency band K1 and the anti-resonance frequency band K2 do not include even a part of the calculation frequency Fc.

In the high frequency component analysis 223a, an inverse fast Fourier transform is performed on the range of frequencies extracted as a plurality of calculation frequencies Fc from the divided data D11 of the first spiral data D1 that have been subjected to the fast Fourier transform. As a result, in the chatter map M1 created by the surface texture estimating unit 22, the unevenness as abrasive grain traces caused by a large number of abrasive grains appearing on the ground circumferential surface W1 of the workpiece W, excluding the noise component, becomes higher. It can be made to appear with precision.

In this embodiment, the rotation speed setting unit 25 includes a fundamental frequency component F1 as a first-order component, and a harmonic component F2 (F21) that is two to five times the fundamental frequency component F1 as a second to fifth-order component. , F22, F23, F24) are included in the gain stable frequency band K0 excluding the resonance frequency band K3. By setting the harmonic component F2 to up to the fifth order component, the accuracy of creating the surface texture map M can be maintained.

In addition, the rotation speed setting unit 25 selects four selected frequencies Fs, which are harmonic components F2 (F21, F22, F23, F24) that are 2 to 5 times the fundamental frequency component F1 as second to fifth order components. It is preferable to set the rotational speed Vw2 of the workpiece W during measurement so that it is included in the gain stable frequency band K0 excluding the resonance frequency band K3.

In the experiment, when the rotational speed Vw2 of the workpiece W during measurement was made much faster than the rotational speed Vw1 of the workpiece W during machining so that the fundamental frequency component F1 as a first-order component was included in the gain stable frequency band K0. In this case, the surface texture S could not be estimated with high accuracy due to vibrations occurring in the components of the grinding machine 1. In order to estimate the surface texture S with high accuracy, it is better to set the rotational speed Vw2 of the workpiece W during measurement so that the fundamental frequency component F1 as a first-order component is included in the gain unstable frequency band K1. It has been found that there are cases. Therefore, by creating the surface texture map M based on the harmonic components F2 from the second order component to the fifth order component, the accuracy of the surface texture map M can be easily maintained.

For example, three or four selected frequencies Fs, which are harmonic components F2 (F21, F22, F23, F24) from the second to fifth order components, are the gain unstable frequency band K1, the anti-resonant frequency band K2, and the resonance frequency band K2. It may be assumed that it is not easy to include the gain stable frequency band K0 except for the frequency band K3. In consideration of such a case, the rotation speed setting unit 25 repeatedly changes the rotation speed Vw2 of the assumed workpiece W during measurement so that at least two selected frequencies Fs are included in the gain stable frequency band K0. The rotational speed Vw2 of the workpiece W at the time of measurement may be determined by calculation. For example, four selected frequencies Fs, which are harmonic components F2 (F21, F22, F23, F24) from the second to fifth order components, are included in the gain stable frequency band K0 excluding the resonance frequency band K3. It is preferable to repeat the calculation by changing the rotational speed Vw2 of the assumed workpiece W at the time of measurement.

As shown in FIG. 6, the workpiece spindle drive unit 26 changes the rotational speed of the workpiece W to the measuring rotational speed Vw2 when the sizing device 3 measures the uneven surface state of the grinding peripheral surface W1 of the workpiece W. maintain. The workpiece spindle drive unit 26 is configured in the control device 10, and acquires information about the measurement rotation speed Vw2 of the workpiece W from the rotation speed setting unit 25, and controls the spindle rotation motor 14a of the headstock 14. Rotate at rotational speed Vw2 during measurement.

The measurement rotation speed Vw2 of the workpiece W is adjusted by the evaluation information storage unit 23, the machining condition acquisition unit 24, the rotation speed setting unit 25, and the workpiece spindle drive unit 26 based on the machining rotation speed Vt1 of the grinding wheel 12 and the workpiece This may be carried out when at least one machining condition of the machining rotational speed Vw1 of W is changed. Once the machining rotational speed Vw1 of the workpiece W is set, the machining is not performed until at least one of the machining rotational speed Vt1 of the grinding wheel 12 and the machining rotational speed Vw1 of the workpiece W is changed. There is no need to adjust the rotational speed Vw2 of the object W during measurement.

8. Relationship between the grinding wheel 12 and the uneven surface on the grinding peripheral surface W1 of the workpiece W Next, the relationship between the grinding wheel 12 and the uneven surface on the grinding peripheral surface W1 of the workpiece W will be described. The grinding wheel 12 is composed of a large number of abrasive grains, a binder that binds the abrasive grains together, and pores. The grinding wheel surface (outer peripheral surface) 121 of the grinding wheel 12 has an uneven surface formed by a large number of abrasive grains. On the grinding circumferential surface W1 of the workpiece W that is ground by the outer circumferential surface of the grinding wheel 12, an uneven surface state is formed by transferring the uneven surface caused by a large number of abrasive grains.

As shown in FIG. 3, the outer diameter of the grinding wheel 12 is larger than the outer diameter of the grinding peripheral surface W1 of the workpiece W. Further, the rotational speed Vt1 of the grinding wheel 12 during machining is larger than the rotational speed Vw1 of the workpiece W during machining. During machining, the grinding wheel 12 rotates multiple times while the workpiece W rotates once. During one rotation of the workpiece W, irregularities are repeatedly formed on the grinding peripheral surface W1 of the workpiece W, which are generated when a large number of abrasive grains collide with each other on the outer peripheral surface of the grinding wheel 12.

FIG. 3 shows a case where the grinding wheel 12 and the workpiece W rotate in the same direction at their contact position. The grinding wheel 12 and the workpiece W may rotate in opposite directions at these contact positions.

During machining, when the machining rotation speed (rotation speed) Vt1 [rps] of the grinding wheel 12 and the machining rotation speed (rotation speed) Vw1 [rps] of the workpiece W are used, the workpiece W rotates once. During this time, each of the abrasive grains of the grinding wheel 12 collides with the grinding peripheral surface W1 of the workpiece W the number of times determined based on Vt1/Vw1. The rotational speed Vw1 of the workpiece W during machining is preferably the rotational speed of the workpiece W at the end of machining. Grinding wheel surface information corresponding to the number of collisions of the abrasive grains is transferred to the grinding peripheral surface W1 of the workpiece W, and is measured by the acceleration sensor 32 of the sizing device 3 as vibrations of a specific frequency.

On the other hand, during measurement, if the rotational speed Vw2 of the workpiece W at the time of measurement is changed from the rotational speed Vw1 of the workpiece W at the time of machining, the vibration of the frequency determined based on Vt1/Vw1×Vw2 is 3 acceleration sensor 32. In the surface texture estimating device 2, vibrations at this frequency are measured as a fundamental frequency component F1. The rotational speed Vw2 of the workpiece W during measurement may not only be changed to be larger than the rotational speed Vw1 of the workpiece W during processing, but also may be changed to be smaller than the rotational speed Vw1 of the workpiece W during processing. There may be.

The rotational speed setting unit 25 of the present embodiment sets the rotational speed ratio Vr (Vt1/Vw1), which is the ratio of the rotational speed Vt1 of the grinding wheel 12 during processing to the rotational speed Vw1 of the workpiece W during processing, to the rotational speed ratio Vr (Vt1/Vw1). The fundamental frequency component F1 is determined based on multiplication by the hourly rotation speed (rotation speed) Vw2 [rps]. The fundamental frequency component F1 is determined based on Vr×Vw2.

9. Other Configurations When the sizing device 3 measures the uneven surface state of the ground peripheral surface W1 of the workpiece W, the signal data acquisition unit 21 estimates the surface texture by using a frequency band of 1/2 or more of the sampling frequency as aliasing noise. It has a configuration that prevents the results of the high frequency component analysis 223a of the section 22 from being influenced. Therefore, it is preferable that the surface texture estimating device 2 further includes a low-pass filter 211.

Specifically, as shown in FIG. 6, the signal data acquisition unit 21 acquires signal data via a low-pass filter 211 whose cutoff frequency is set to a frequency higher than the gain stable frequency band K0. The cutoff frequency may be set to the upper limit frequency of the natural vibration characteristic K stored in the evaluation information storage section 23. In the evaluation information storage unit 23 of this embodiment, natural vibration characteristics K of frequencies up to 2500 Hz are stored. The cutoff frequency of the low-pass filter 211 may be set to sufficiently attenuate frequency components exceeding 2500 Hz.

Further, the signal data acquisition unit 21 acquires signal data using a sampling frequency that is twice or more than the cutoff frequency. In the present embodiment, the sampling frequency of the signal data acquisition unit 21 is set to 5000 Hz or more, which is twice or more the upper limit frequency of the natural vibration characteristic K stored in the evaluation information storage unit 23.

As shown in FIG. 1, the grinding machine 1 may include a determination unit 101 that performs various determinations using a surface texture map M estimated and created by the surface texture estimation device 2. The determination unit 101 may determine the quality of the grinding process of the workpiece W based on the surface texture map M. The surface texture estimating device 2 stores a reference surface texture map that serves as a reference when good grinding is performed on the workpiece W. The surface texture map M created each time the process is performed once or a predetermined number of times is compared with a reference surface texture map. Then, the determination unit 101 determines that the grinding process is defective when the surface texture S of the ground circumferential surface W1 of the workpiece W that has been subjected to the grinding process has deteriorated compared to the surface texture in the reference surface texture map. You may.

The determination unit 101 may determine, based on the surface texture map M, whether it is necessary to adjust the machining conditions of the workpiece W to be machined from the next time onwards. The processing conditions for the workpiece W include, in addition to the rotational speed Vt1 of the grinding wheel 12 during processing and the rotational speed Vw1 of the workpiece W during processing, the feed rate (amount of cut) of the grinding wheel 12 in the X-axis direction, etc. . In this case as well, the surface texture estimating device 2 stores a reference surface texture map, and the determination unit 101 stores a surface texture map that is created each time the grinding machine 1 grinds the workpiece W once or a predetermined number of times. Compare M with a reference surface texture map. Then, the determination unit 101 determines that it is necessary to adjust the machining conditions when the surface texture S of the ground peripheral surface W1 of the workpiece W subjected to the grinding process has deteriorated compared to the surface texture in the reference surface texture map. It may be determined that

The determination unit 101 may determine whether or not the correction timing of the grinding wheel 12 needs to be adjusted based on the surface texture map M. The correction timing of the grinding wheel 12 indicates the frequency at which the grinding wheel 12 is corrected. Correction of the grinding wheel 12 includes truing (reshaping) to correct the run-out of the grinding wheel 12, shape, etc., and dressing (reshaping) to correct the protruding amount of the abrasive grains, creation of the cutting edge of the abrasive grains, etc. and so on. In this case as well, the surface texture estimating device 2 stores a reference surface texture map, and the determination unit 101 stores a surface texture map that is created each time the grinding machine 1 grinds the workpiece W once or a predetermined number of times. Compare M with a reference surface texture map. Then, when the surface texture S of the ground circumferential surface W1 of the workpiece W that has been subjected to grinding has deteriorated compared to the surface texture in the reference surface texture map, the determination unit 101 shortens the frequency at which the grinding wheel 12 is corrected. It may be determined that there is a need to do so.

10. Effects In the surface texture estimating device 2 of this embodiment, the evaluation information I of the natural vibration characteristic K by the acceleration sensor 32 is stored, and the rotational speed Vw1 of the workpiece W during machining is By intentionally changing the rotational speed Vw2 of the workpiece W during measurement, the influence of the natural vibration characteristic K on the estimation of the surface texture S is alleviated. Specifically, in the evaluation information I of the evaluation information storage unit 23, a stable gain frequency band K0, an unstable gain frequency band K1, an anti-resonant frequency band K2, and a resonant frequency band K3 are set for the natural vibration characteristic K. There is.

Then, the rotational speed setting unit 25 assumes a measurement rotational speed Vw2 of the workpiece W at the time of measurement based on the relationship between the rotational speed Vt1 of the grinding wheel 12 during processing and the rotational speed Vw1 of the workpiece W during processing. At this time, the selected frequencies Fs of at least two of the harmonic components F2 from the second order component to the fifth order component included in the first spiral data D1 of the signal data acquisition unit 21 exceed the resonance frequency band K3. The rotational speed Vw2 of the workpiece W at the time of measurement is set so that it is included in the gain stable frequency band K0.

By setting the rotational speed Vw2 of the workpiece W at the time of measurement in this way, the gain unstable frequency band K1 of the natural vibration characteristic K is included in the first spiral data D1 acquired by the signal data acquisition unit 21 at the time of measurement. It is possible to prevent the influence of noise due to the anti-resonant frequency band K2 and the resonant frequency band K3 from occurring. By reducing the error factor, the accuracy of estimating the surface texture S by the surface texture estimating section 22 can be improved, and the accuracy of the surface texture map M can be improved.

Therefore, according to the surface texture estimating device 2 of this embodiment, the accuracy of the surface texture map M can be improved by excluding the influence of noise due to the gain unstable frequency band K1 of the natural vibration characteristic K.

The present invention is not limited only to the embodiments, and can be configured into further different embodiments without departing from the gist thereof. Further, the present invention includes various modifications, modifications within equivalent ranges, and the like. Furthermore, various combinations, forms, etc. of constituent elements envisioned from the present invention are also included in the technical idea of the present invention.

1 Grinding machine 12 Grinding wheel 2 Surface texture estimation device 20 Arithmetic processing device 21 Signal data acquisition section 22 Surface texture estimation section 23 Evaluation information storage section 24 Machining condition acquisition section 25 Rotation speed setting section 3 Sizing device 32 Acceleration sensor 34 Displacement sensor W Workpiece W1 Grinding surface S Surface texture F1 Fundamental frequency component F2 Harmonic component Fs Selected frequency Fc Calculation frequency M Surface texture map G Gain ΔG Variation K Natural vibration characteristics I Evaluation information K0 Gain stable frequency band K1 Gain unstable frequency Band K2 Anti-resonant frequency band K3 Resonant frequency band Vt1 Rotation speed of grinding wheel during processing Vw1 Rotation speed of workpiece during processing Vw2 Rotation speed of workpiece during measurement

Claims (12)

A surface texture estimation device for estimating the surface texture of a ground peripheral surface of a workpiece that has been ground by a grinding wheel in a grinding machine,
a sizing device that is provided on the grinding machine and measures the diameter of the peripheral surface to be ground while the workpiece is being ground while being rotated;
The grinding of the workpiece due to the grinding wheel to which the uneven surface of the grinding wheel has been transferred is based on signal data output from a sensor provided in the sizing device during measurement after the grinding process of the workpiece. an arithmetic processing device that estimates an uneven surface state of the peripheral surface as the surface texture;
Equipped with
The arithmetic processing device is
A signal that acquires the signal data when the sizing device and the workpiece are relatively moved in the axial direction of the workpiece while rotating the workpiece, corresponding to the uneven surface state of the grinding peripheral surface. a data acquisition section;
When a vibration with a changed frequency is applied to the sizing device as an input, in the natural vibration characteristic as a frequency response characteristic of the output data output from the sensor, the variation in the gain of the natural vibration characteristic is within a predetermined value. Stores evaluation information in which a gain stable frequency band included in the gain stable frequency band and a gain unstable frequency band whose frequency is lower than the gain stable frequency band and whose variation in the gain of the natural vibration characteristic exceeds the predetermined value are set. an evaluation information storage unit for
a machining condition acquisition unit that acquires a machining rotational speed Vt1 of the grinding wheel and a machining rotational speed Vw1 of the workpiece during grinding of the workpiece by the grinding wheel;
Based on the relationship between the machining rotation speed Vt1 of the grinding wheel and the machining rotation speed Vw1 of the workpiece, when the measurement rotation speed Vw2 of the workpiece at the time of measurement is assumed, the signal data includes: A rotation for setting the rotational speed Vw2 of the workpiece at the time of measurement so that at least two selected frequencies of a fundamental frequency component to be measured and a harmonic component of the fundamental frequency component are included in the gain stable frequency band. a speed setting section;
Based on the signal data acquired by the signal data acquisition unit when the workpiece is rotated at the measurement rotation speed Vw2 during the measurement, the uneven surface condition of the grinding peripheral surface is determined based on the surface texture. a surface texture estimating unit that estimates as
A surface texture estimation device comprising: The rotation speed setting section includes:
The rotational speed Vw2 of the workpiece during measurement is determined by changing the assumed rotational speed Vw2 of the workpiece during measurement and performing repeated calculations so that at least two of the selected frequencies are included in the gain stable frequency band. The surface texture estimating device according to claim 1. The surface texture estimating unit includes:
Based on the signal data acquired by the signal data acquisition unit when the workpiece is rotated at the measurement rotation speed Vw2 during the measurement, a plurality of predetermined ranges individually including the selected frequency are selected. The surface texture estimating device according to claim 1 or 2, wherein a calculation frequency is extracted, and the uneven surface state of the ground circumferential surface is estimated as the surface texture based on the amplitude of the calculation frequency. The rotation speed setting section includes:
The basic frequency component is calculated based on multiplying the rotational speed ratio Vr, which is the ratio of the rotational speed Vt1 of the grinding wheel during processing to the rotational speed Vw1 of the workpiece during processing, by the rotational speed Vw2 of the workpiece during measurement. The surface texture estimating device according to claim 1 or 2, wherein the surface texture estimating device calculates the following. The evaluation information in the evaluation information storage section includes:
In addition to the gain stable frequency band and the gain unstable frequency band, there is an anti-resonance whose frequency is higher than the gain stable frequency band and where the gain of the natural vibration characteristic fluctuates up and down due to anti-resonance characteristics and which cannot be compensated for. The frequency band is set,
The rotation speed setting section includes:
The rotational speed Vw2 of the workpiece during measurement is set such that at least two of the selected frequencies exclude the gain unstable frequency band and the anti-resonance frequency band and are included in the gain stable frequency band. 2. The surface texture estimating device according to 1 or 2. The gain stable frequency band of the evaluation information in the evaluation information storage section includes:
It includes a resonant frequency band in which the gain of the natural vibration characteristic fluctuates up and down due to the resonance characteristic and the gain can be compensated for,
The rotation speed setting section includes:
The rotational speed Vw2 of the workpiece during measurement is set such that at least two of the selected frequencies are included in the gain stable frequency band excluding the gain unstable frequency band and excluding the resonance frequency band. 2. The surface texture estimating device according to 1 or 2. The rotation speed setting section includes:
At least two of the selected frequencies of the fundamental frequency component as a first-order component and harmonic components 2 to 5 times the fundamental frequency component as second to fifth-order components are in the gain stable frequency band. The surface texture estimating device according to claim 1 or 2, wherein the rotational speed Vw2 of the workpiece at the time of measurement is set so as to be included in the rotational speed Vw2 of the workpiece. The rotation speed setting section includes:
The rotational speed of the workpiece at the time of measurement is adjusted such that the four selected frequencies, which are harmonic components 2 to 5 times the fundamental frequency component as second to fifth order components, are included in the gain stable frequency band. The surface texture estimating device according to claim 1 or 2, which sets Vw2. The signal data acquisition unit includes:
The signal data is acquired through a low-pass filter whose cutoff frequency is set to a higher frequency than the gain stable frequency band, and the signal data is acquired at a sampling frequency that is at least twice the cutoff frequency. The surface texture estimation device according to item 1 or 2. The sizing device includes a contact member that comes into contact with the grinding peripheral surface of the workpiece and is displaced to follow the uneven surface state of the grinding peripheral surface, and an acceleration sensor as the sensor disposed on the contact member. The surface texture estimating device according to claim 1 or 2, comprising: A grinding machine comprising the surface texture estimating device according to claim 1 or 2. Based on the surface texture estimated by the surface texture estimating device, determining the quality of grinding of the workpiece, determining whether it is necessary to adjust the machining conditions of the workpiece to be machined from next time onwards, and correcting the grinding wheel. The grinding machine according to claim 11, further comprising a determining unit that executes at least one of determining whether timing adjustment is necessary.

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