JP2004279130A - Rotational accuracy measuring method and rotational accuracy measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotational accuracy measuring method and a rotational accuracy measuring instrument for correcting a phase shift within one turn. <P>SOLUTION: According to this rotational accuracy measuring method, time series data comprising sampled values of prescribed cycles exhibiting radial or axial displacement of a rotating body rotating centering around its axis are divided for each of rotation cycles of the rotating body and formed into blocks to prepare a plurality of data blocks. A phase shift is corrected for each of the rotation cycles on the plurality of prepared data blocks and an index is calculated expressing the rotational accuracy of the rotating body based on the plurality of data blocks whose phase shifts are corrected. Further, a phase shift within a rotation cycle of each data block of the rotating body is detected based on the phase of a maximum point and/or a minimum point of the sampled values (S2, S4, S6) to divide the shift among sampled values in a prescribed range in the vicinity of the maximum point and/or the minimum point of the data block (S8). A phase shift in each of the sampled values is corrected based on the divided shift (S10). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotation accuracy measurement method and a rotation accuracy measurement device for measuring the rotation accuracy of a rotating body that rotates about an axis.
[0002]
[Prior art]
2. Description of the Related Art A rotation accuracy measuring device that measures the rotation accuracy of a rotating body (for example, a spindle that is rotated by a motor) supported by a rolling bearing or a fluid bearing or the like has conventionally used a time-series data indicating the displacement of the rotating body as a rotating body. A large amount of displacement data was collected by sampling regardless of the rotation of the, and data processing was performed on the large amount of displacement data collectively. In this data processing, for example, data indicating a frequency spectrum (hereinafter, referred to as “FFT”) is performed on displacement data (hereinafter, referred to as “collected data”) obtained in a time-series manner, Hereinafter, “spectral data” is calculated. Next, by removing a synchronous runout error (RRO; Repeatable Run Out) from the spectrum data, an asynchronous runout error (NRRO; Non Repeatable Run Out) corresponding to the displacement of the rotating body that is not repeated every rotation is obtained. ing.
[0003]
Patent Literature 1 discloses a method and an apparatus for inspecting the rotational accuracy of a ball bearing that can measure NRRO of a single ball bearing by a simple operation. Further, Patent Literature 2 discloses a rotational accuracy and dynamic torque measuring device for a radial rolling bearing in which the rotational asynchronous vibration and the dynamic torque of the radial rolling bearing are associated with each other to enable accurate measurement. Patent Document 3 discloses a rolling bearing rotational accuracy and dynamic torque measuring device that makes it possible to accurately and freely measure the rotational asynchronous vibration and the dynamic torque of the rolling bearing in both the radial and axial directions so that they can be accurately measured. .
[0004]
[Patent Document 1]
JP-A-11-31588 [Patent Document 2]
JP 2000-155073 A [Patent Document 3]
JP 2001-194270A [0005]
[Problems to be solved by the invention]
However, in the conventional rotation accuracy measuring device, rotation unevenness of a motor or the like for rotating the rotating body has a great influence on the measurement. Further, since the above-mentioned collected data is time-series data collected regardless of the rotation of the rotating body, when the FFT is performed in the data processing, the collected data is smoothly reduced to 0 outside a predetermined section. In such a manner, the acquired data is previously appropriately weighted by the window function. In general, when a window function is used, the spectrum obtained by the FFT spreads. Therefore, the use of this function has a great effect on the measurement by the conventional rotation accuracy measuring device. As described above, in the conventional measuring device, since the influence of the rotation unevenness of the motor and the window function is great, it is difficult to perform advanced measurement of the rotation accuracy, that is, accurate calculation of RRO, NRRO, roundness, and the like.
[0006]
In view of the circumstances as described above, the applicant of the present application divides the time-series data for each rotation cycle of the rotating body into blocks, thereby creating block data including a plurality of data blocks, and creating the block data. An index indicating the rotation accuracy of the rotating body is calculated based on the block data thus obtained, and a rotation accuracy measuring device capable of reducing the influence of the rotation unevenness of the motor and the effect of the window function is disclosed in Japanese Patent Application Nos. 2002-018402 and 2002. -036777.
[0007]
In this rotation accuracy measuring device, it is possible to correct the phase shift for each rotation due to uneven rotation of the motor, but there is a problem that the phase shift within one rotation cannot be corrected.
The present invention has been made in view of the above-described circumstances, and has as its object to provide a rotation accuracy measurement method and a rotation accuracy measurement device capable of correcting a phase shift within one rotation.
[0008]
[Means for Solving the Problems]
The rotation accuracy measuring method according to the first aspect of the present invention provides a method of measuring time-series data including a sampling value of a predetermined cycle indicating a radial or axial displacement of a rotating body that rotates about an axis for each rotation cycle of the rotating body. Divide and block to create a plurality of data blocks, correct the phase shift for each rotation cycle of the created data blocks, and, based on the plurality of data blocks corrected for the phase shift, A rotation accuracy measurement method for calculating an index indicating rotation accuracy, wherein a phase shift in a rotation cycle of the rotating body of the data block is detected based on a phase of a maximum point and / or a minimum point of the sampled value. And allocating the detected deviation to sampled values in a predetermined range around the maximum point and / or the minimum point of the data block, and correcting a phase deviation for each of the sampled values based on the distributed deviation. And it features.
[0009]
A rotation accuracy measuring device according to a second aspect of the present invention includes: a unit for acquiring time-series data including a sampling value of a predetermined cycle indicating a radial or axial displacement of a rotating body that rotates about an axis; Means for dividing the time-series data into blocks for each rotation cycle of the rotating body to create a plurality of data blocks, and correcting a phase shift of the plurality of data blocks created by the means for each rotation cycle. A rotation accuracy measuring device comprising: means for calculating an index indicating rotation accuracy of the rotator based on a plurality of data blocks in which the deviation has been corrected by the means; Detecting means for detecting a phase shift within a cycle based on the phase of the maximum point and / or the minimum point of the sampled value; and detecting the shift detected by the detection means for the maximum point and the maximum value of the data block. Or a distribution means for distributing the sampled values in a predetermined range around the minimum point, based on the deviation 該配 partial unit is allocated, characterized in that it comprises a means for correcting the deviation of the sampled values every phase.
[0010]
In the rotation accuracy measurement method according to the first invention and the rotation accuracy measurement device according to the second invention, the acquisition unit includes time-series data consisting of sampled values of a predetermined cycle indicating radial or axial displacement of the rotating rotating body. Means for obtaining and creating a plurality of data blocks by dividing the obtained time-series data for each rotation cycle of the rotating body and dividing the data into blocks. The means for correcting corrects the phase shift of each of the plurality of data blocks created for each rotation cycle, and the means for calculating calculates an index indicating the rotational accuracy of the rotating body based on the corrected plurality of data blocks. .
[0011]
The detecting means detects and distributes a phase shift within the rotation period of the rotator of the data block based on the phase of the maximum point and / or the minimum point (both or both of the maximum point and the minimum point) of the sampled value. Means distributes the detected deviation to a predetermined range of sampled values around the maximum point and / or the minimum point of the data block. The correcting unit corrects the phase shift for each sampling value based on the shift distributed by the distribution unit.
As a result, the phase shift within one rotation can be corrected, and the phase shift within one rotation can be corrected while avoiding a portion where the sampling value fluctuates rapidly. The rotation accuracy measurement method and the rotation accuracy measurement device that improve the accuracy can be realized.
[0012]
In the rotation accuracy measuring device according to a third aspect, the distribution unit is configured to distribute the deviation detected by the detection unit to the sampled values in the predetermined range based on the order of the sampled values in the data block. It is characterized by having.
[0013]
In this rotation accuracy measuring device, the distributing means distributes the deviation detected by the detecting means to the sampling values within a predetermined range based on the order of the sampled values in the data block, so that the phase deviation within one rotation is corrected. The phase shift within one rotation can be corrected in accordance with the magnitude of the shift for each sampled value while avoiding a portion where the sampling value fluctuates rapidly. And a rotation accuracy measuring device and a rotation accuracy measurement device that improve the correction accuracy of the rotation accuracy can be realized.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings showing the embodiments.
FIG. 1 is an explanatory view schematically showing a configuration of an embodiment of a rotational accuracy measuring device according to the present invention, and FIG. 2 is a plan view showing a state when the rotational accuracy measuring device measures a rotating body. It is. The rotation accuracy measurement device is a measurement device that measures the rotation accuracy of the rotating body 10 that is supported by bearings and is rotated about a predetermined rotating shaft 11 by a motor (not shown). And time-series data consisting of sampled values indicating the radial displacement of the rotating body 10 based on the detection signal Sd of the displacement sensor 20 and the collected data as the time-series data. And a data collection processing device 30 that processes the data.
[0015]
The displacement sensor 20 is disposed near the outer peripheral surface of the rotating body 10, detects the distance between the outer peripheral surface and the displacement sensor 20, and outputs the detection result as a detection signal Sd indicating the radial displacement of the rotating body 10. . When detecting the axial displacement of the rotating body 10 and measuring the rotational accuracy with respect to the axial displacement, as shown by a broken line in FIG. A non-contact type displacement sensor 21 for detecting displacement in the direction is arranged, and a signal output from the displacement sensor 21, that is, a signal indicating a distance between the upper surface of the rotating body 10 and the displacement sensor 21 is used as a detection signal Sd. Good.
[0016]
The data collection processing device 30 has a configuration in which a CPU 31 as a central processing unit, an input interface unit 32, a memory 33, and a display control unit 34 are connected by a bus, and a display unit 36 is connected to the display control unit 34. I have. The detection signal Sd from the displacement sensor 20 is input to the input interface unit 32. The input interface unit 32 has an A / D converter, and the detection signal Sd is temporarily stored in the memory 33 as digital data sampled thereby (hereinafter, this digital data is referred to as “original data”). ). The input interface unit 32 constitutes, together with the displacement sensor 20, means for acquiring time-series data representing the displacement of the rotating body 10.
[0017]
By executing a predetermined program stored in the memory 33 in advance, the CPU 31 sequentially performs data processing such as DC cut processing, period division processing, phase correction, rate conversion, and FFT on original data. Accordingly, the data collection processing device 30 includes a DC cut unit 111 (means for acquiring time-series data), a period division unit 112 (means for creating a plurality of data blocks), and a phase correction unit 113 as shown in FIG. It operates as a device including (means for correcting a phase shift), a rate conversion unit 114, and a signal processing unit 115 (means for calculating an index).
[0018]
The DC cut unit 111 removes a DC component from the detection signal Sd output from the displacement sensor 20. Specifically, the DC cut unit 111 performs signal processing on original data which is digital data representing the detection signal Sd, and performs detection processing on the detection signal Sd. , Digital data representing a signal from which a DC component has been removed is created as sampling data Da (this signal processing is referred to as “DC cut processing”). Although the DC cut unit 111 is realized by software, a DC component cut-off circuit is provided in the input interface unit 32 to remove the DC component from the detection signal Sd, and then the A / D converter converts the DC data into a sampled data. Da may be created. In this case, the DC cut unit 111 is realized as hardware, and forms a part of the input interface unit 32.
[0019]
The cycle dividing unit 112 creates the block data Db composed of a plurality of data blocks by dividing the sampled data Da created by the DC cutting unit 111 for each rotation cycle of the rotating body 10 and dividing the data into blocks. The processing is called “periodic division processing”). Specifically, a zero point corresponding to Sd = 0 is obtained from the sampling data Da which is digital data representing the detection signal Sd, and the sampling data Da is divided for each rotation cycle based on the zero point. Obtain block data Db. For example, when the sampled data Da corresponding to the section as shown in FIG. 4 is obtained from the DC cut unit 111 in the detection signal Sd, based on the zero point detected from the sampled data Da, FIG. Blocked data Db composed of four data blocks Db1, Db2, Db3, Db4 as shown is obtained.
[0020]
The number of digital signal values (sampled values indicating the displacement of the rotating body 10) (hereinafter referred to as "data number") constituting each of these four data blocks Db1, Db2, Db3 and Db4 (the number of sampling points in one rotation cycle) Are usually not equal due to uneven rotation of the motor. For example, as shown in FIG. 6, the data numbers of the data blocks Db1, Db2, Db3, and Db4 are n1 and n2, respectively. , N3 and n4. When a driving unit (not shown) including a motor for rotating the rotating body 10 outputs a signal synchronized with the rotation cycle (for example, a signal in which one pulse appears every one rotation) as the index pulse Sip, Instead of the zero point detection described above, the period division processing may be performed based on the index pulse Sip.
[0021]
The phase correction unit 113 corrects the phase shift of each of the data blocks Db1, Db2, Db3, and Db4 of the block data Db divided and blocked by the period division unit 112, and also corrects each of the data blocks Db1, Db2, The phase shift in Db3 and Db4 (phase shift for each sampling point) is corrected, and the corrected blocked data Dc is output. The details of the correction of the phase shift for each sampling point will be described later.
[0022]
The rate conversion unit 114 performs the interpolation processing (resampling and resampling) on the block data Dc including a plurality of data blocks in which the number of data varies as described above, so that the number of data in each data block is the same. To That is, the number of sampling points of each data block is made equal by rate conversion.
At this time, the number of data of each data block is set to a power of 2 in consideration of FFT (Fast Fourier Transform) performed by the signal processing unit 115. For example, by performing rate conversion on the block data Db (Dc) as shown in FIG. 6, block data Dd composed of data blocks whose data count is all 2 ^m can be obtained.
[0023]
The signal processing unit 115 is a unit for calculating an index indicating the rotation accuracy, and calculates spectrum data by performing FFT on the block data Dd after rate conversion without using a window function. Then, based on the calculated spectrum data, RRO, NRRO, roundness, and the like are obtained by a method similar to the conventional method.
Indices indicating the rotational accuracy of the rotating body 10, such as RRO, NRRO, and roundness, obtained in this manner are stored in the memory 33 as measurement results, and transmitted to the display control unit 34 based on another predetermined program. It is sent and displayed on the display unit 36 by the display control unit 34.
[0024]
The operation of correcting a phase shift (a phase shift at each sampling point) in a data block (within the rotation cycle of the rotating body 10) in the phase correction unit 113 of such a rotation accuracy measuring device will be described below. This will be described with reference to the flowchart of FIG.
The phase correction unit 113 first detects the maximum point and the minimum point of the sampled value in each data block, and as shown in FIG. 8, the number of sampling points E1, E2 from the head to the minimum point in each data block. , E3, E4 and the number of sampling points F1, F2, F3, F4 up to the local maximum point (S2), and calculates the average value, thereby calculating the average phase of each local maximum point and each local minimum point. (S4).
[0025]
Next, the phase correction unit 113 calculates a phase shift between the local maximum point and its average phase (S4) in the data block of interest and a phase shift between the local minimum point and its average phase (S4) (S6). ), And then the phase shift is distributed to (the phase of) each sampled value (S8).
When allocating the phase shift to each sampled value (S8), the phase corrector 113 sets the phase shift of the minimum point to Sp / 4 (Sp is 1 data) before and after the minimum point, as shown in FIG. It is distributed to each sampled value within the range of the number of sampling points (number of sampled values) in the block, and the phase shift of the local maximum point is allocated to each sampled value within the range of Sp / 4 before and after the local maximum point. In the distribution, weighting is performed according to the order N (1, 2,... Sp) of the sampled values from the head of the data block.
[0026]
For example, when distributing the phase deviation Zs of the minimum point in the data block of interest, the deviation ZN distributed to the sampling points N (= Sp / 8 to 3Sp / 8) is
It is assumed that ZN = 4N × Zs / Sp.
Similarly, when distributing the phase deviation Zd of the local maximum point in the data block of interest, the deviation ZN distributed to the sampling points N (= 5Sp / 8 to 7Sp / 8) is
It is assumed that ZN = 4N × Zd / Sp.
[0027]
Next, the phase correction unit 113 corrects the phase of each sampling point by subtracting the phase shift (S8) allocated to each sampling point from the phase of each sampling point (S10).
Next, if there is a data block for which the phase of each sampling point should be corrected next (S12), the phase correction unit 113 shifts the phase between the maximum point in the data block and the average phase (S4), and The phase shift between the minimum point and the average phase (S4) is calculated (S6), and then the phase shift is distributed to (the phase of) each sampled value (S8). If there is no data block whose phase should be corrected (S12), the process returns.
In the above-described embodiment, the correction is performed based on the phase shift between the local maximum point and the local minimum point. However, the correction may be performed based on the phase shift between either the local maximum point or the local minimum point.
[0028]
【The invention's effect】
According to the rotation accuracy measurement method according to the first invention and the rotation accuracy measurement device according to the second invention, the phase shift within one rotation can be corrected, and the correction of the phase shift within one rotation is sampled. This can be performed while avoiding a portion where the value fluctuates abruptly, and a rotation accuracy measuring method and a rotation accuracy measuring device in which the correction accuracy of the phase shift is improved can be realized. In addition, the variation in the displacement of the portion where the sampling value fluctuates rapidly decreases.
[0029]
According to the rotation accuracy measuring device according to the third aspect of the present invention, the phase shift within one rotation can be corrected, and the phase shift within one rotation can be corrected by avoiding a portion where the sampling value fluctuates rapidly. In addition, the method can be performed in accordance with the magnitude of the deviation for each sampled value, and a rotational accuracy measuring method and a rotational accuracy measuring device that improve the correction accuracy of the phase deviation can be realized. In addition, the variation in the displacement of the portion where the sampling value fluctuates rapidly decreases.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram schematically showing a configuration of an embodiment of a rotation accuracy measuring device according to the present invention.
FIG. 2 is a plan view showing a state when the rotation accuracy measuring device according to the present invention measures a rotating body.
FIG. 3 is a block diagram illustrating a configuration example of a data collection processing device of the rotation accuracy measuring device according to the present invention.
FIG. 4 is an explanatory diagram showing an example of collected data of the rotation accuracy measuring device according to the present invention.
FIG. 5 is an explanatory diagram showing the operation of the rotation accuracy measuring device according to the present invention.
FIG. 6 is an explanatory view showing the operation of the rotation accuracy measuring device according to the present invention.
FIG. 7 is a flowchart showing the operation of the rotation accuracy measuring device according to the present invention.
FIG. 8 is an explanatory diagram showing the operation of the rotation accuracy measuring device according to the present invention.
FIG. 9 is an explanatory diagram showing the operation of the rotation accuracy measuring device according to the present invention.
[Explanation of symbols]
Reference Signs List 10 Rotating body 11 Rotating axes 20, 21 Displacement sensor 30 Data collection processing device 31 CPU
32 input interface unit 33 memory 36 display unit 111 DC cut unit (means for acquiring time-series data)
112 Period division unit 113 Phase correction unit (means for correcting phase deviation)
114 Rate conversion unit 115 Signal processing unit (means for calculating index)

Claims (3)

A plurality of data blocks is created by dividing time-series data consisting of sampled values of a predetermined cycle indicating a radial or axial displacement of a rotating body rotating about an axis for each rotation cycle of the rotating body and dividing the data into blocks. A rotation accuracy measurement for correcting a phase shift of each of the plurality of created data blocks for each rotation cycle, and calculating an index indicating a rotation accuracy of the rotating body based on the plurality of data blocks in which the phase shifts are corrected. The method,
A phase shift in the rotation cycle of the rotator of the data block is detected based on a phase of a local maximum point and / or a local minimum point of the sampled value, and the detected shift is detected by the local maximum point and / or the data block. A rotation accuracy measuring method, wherein the rotational accuracy is distributed to sampling values in a predetermined range around a minimum point, and the phase deviation for each of the sampling values is corrected based on the distributed deviation. Means for acquiring time-series data consisting of sampled values of a predetermined period indicating a radial or axial displacement of a rotating body rotating about an axis, and the time-series data acquired by the means for rotating the rotating body. Means for dividing a plurality of data blocks into blocks to create a plurality of data blocks, means for correcting a phase shift of the plurality of data blocks created by the means for each rotation cycle, and a plurality of means for correcting the shifts A means for calculating an index indicating the rotation accuracy of the rotating body, based on the data block of, the rotation accuracy measurement device,
Detecting means for detecting a phase shift in the rotation period of the rotating body of the data block based on a phase of a local maximum point and / or a local minimum point of the sampled value; and detecting the shift detected by the detection means in the data block. Allocating means for allocating to the sampling values in a predetermined range around the maximum point and / or the minimum point, and means for correcting a phase deviation for each of the sampling values based on the deviation distributed by the distribution means. A rotation accuracy measuring device, characterized in that: 3. The rotation accuracy measuring apparatus according to claim 2, wherein the distribution unit distributes the deviation detected by the detection unit to the sampled values in the predetermined range based on the order of the sampled values in the data block. .

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