JP2001141594A - Dynamic balancing machine and its unbalance caluculation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure precisely the magnitude and the direction of unbalance of a rotor. SOLUTION: A vibration signal obtained from a vibration sensor of a dynamic unbalance testing machine is subjected to A/D conversion and taken in as a digital value, while an X-direction standard function and a Y-direction standard function are generated based on a rotary standard pulse. After multiplying the vibration signal and each standard function together, averaging processing by a digital filter is executed, to thereby operate correlation coefficients. The magnitude and the direction of unbalance is operated based on an X-direction correlation coefficient and a Y-direction correlation coefficient obtained in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic balance test apparatus for measuring a balance state when a test body is rotated, and a method of calculating an unbalance performed by the apparatus.

[0002]

2. Description of the Related Art In a dynamic balance test apparatus, generally, an unbalance signal generated by rotating a specimen is detected by a detector, and the magnitude of the unbalance of the specimen is obtained from its amplitude value. In addition, rotation obtained by detecting a rotation reference position such as a mark on the surface of the specimen or a surface characteristic of the specimen by a rotational phase detector constituted by a non-contact sensor such as a laser sensor or a photo sensor. From the phase relationship between the reference pulse and the unbalanced signal, an unbalanced direction (unbalanced angle) existing in the specimen is obtained.

In order to obtain the magnitude of the unbalance and the angle of the unbalance, two types of reference waveforms are generated based on the position of the reference pulse generated by the rotation reference sensor, and the cross-correlation between the reference waveform and the vibration signal detected by the vibration detector is performed. Was performed by analog circuits. That is, a cosine wave is generated as a reference waveform in the X direction, a sine wave is generated as a reference waveform in the Y direction, each signal is multiplied by an output signal from the vibration sensor, and further integrated and averaged to obtain X. The unbalance amount between the directional component and the Y-direction component is obtained, and this value is taken into a computer via an A / D converter to calculate and display the magnitude and direction of the unbalance.

[0004] Since the conventional method is a method using an analog circuit, an offset error of an intervening amplifier and a full-scale error when a measurement range is changed are large.
In addition, when the reference waveform is multiplied by the output signal from the vibration sensor and averaged by integration, it takes time until the output of the averaging process is stabilized, and rapid measurement cannot be performed.
Further, the analog circuit includes a non-linear error, and various filtering processes are required to process the vibration signal. However, it has been difficult to freely set the filtering process.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has little effect on errors and instability of a measurement circuit, and has a stable measurement value when a range is switched. Accordingly, it is an object of the present invention to provide a dynamic balance test apparatus having high accuracy and a short time for obtaining a measured value, and a method for measuring the unbalance thereof.

[0006]

In order to solve the above-mentioned problems, the present invention provides a method for calculating the magnitude and direction of an unbalance from a vibration signal detected when a specimen is rotated and a rotation reference position signal. In a balance test apparatus, a vibration sensor for detecting vibration of a specimen, an A / D converter for converting an output of the vibration sensor into a digital signal, a rotation reference sensor for detecting a rotation reference position of the specimen, First calculating means for calculating a reference function in the X and Y directions based on the reference signal of the rotation reference sensor; and an output of the A / D converter and the X direction calculated by the first calculating means. A second calculating means for calculating a correlation coefficient between the X direction and the Y direction based on a reference function in the Y direction; and a second calculating means for calculating the magnitude and direction of the unbalance of the specimen from the correlation coefficient between the X direction and the Y direction. Note that the calculation means of (3) is provided. To.

Further, in an unbalance calculation method of a dynamic balance test apparatus for calculating the magnitude and direction of an unbalance from a vibration signal detected when the specimen is rotated and a reference position signal of the rotation, an output from the vibration sensor is calculated. A / D converted and fetched as a digital signal, a reference function in the X and Y directions is calculated based on a reference signal from the rotation reference sensor, and a X-direction between the digital signal from the vibration sensor and the reference function is calculated. And a Y-direction correlation coefficient, and the magnitude and direction of the unbalance of the specimen are calculated based on the X-direction and Y-direction correlation coefficients.

[0008] In the dynamic balance test apparatus of the present invention, the output of the vibration sensor is immediately A / D converted into a digital signal. On the other hand, a reference function in the X and Y directions is digitally calculated based on a reference position signal from the rotation reference sensor.
By calculating the digital data of these vibration sensors and the digital data of the reference function, the correlation coefficient in the X direction and the Y direction is obtained, and the magnitude and direction of the unbalance of the specimen are calculated based on the correlation coefficient. In addition, there is little room for error in the final result, and a highly accurate unbalance amount can be obtained. In addition, since various digital filters can be employed in obtaining the correlation coefficient, not only the accuracy of the result is high but also the measurement time can be shortened.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the dynamic balance test device of the present invention. A belt 2 is wound around the specimen W in a state where both ends are supported by bearings 1 a and 1 b, and rotation is given through the belt 2 by driving a motor 3. Each bearing 1a, 1b
Is displaceably supported on the tester frame via springs 4a and 4b, and when the specimen W rotates, the specimen W
The bearings 1a and 1b are displaced due to the unbalance existing in the bearing. The displacements (speeds) of these bearings 1a, 1b are detected as unbalanced vibration signals on the left and right surfaces of the specimen W by the moving coil type vibration sensors 5a, 5b. Each of these unbalanced signals is a sine-wave signal. After being amplified by the amplifiers 11a and 11b, the signals are digitized by the A / D converters 12a and 12b, and the instantaneous value is taken into the arithmetic unit 13.

A laser sensor 6 is disposed near the surface of the specimen W supported by the bearings 1a and 1b, and the laser sensor 6 detects a mark M provided on the surface of the specimen W. After the detection signal is amplified by the amplifier 14, it is shaped into a pulse signal of a predetermined shape by the pulse shaping circuit 15, and is taken into the arithmetic unit 13 as a rotation reference pulse of the specimen W.

The arithmetic unit 13 is a digital arithmetic unit mainly composed of a DSP (Digital Signal Processor). In addition to the above-mentioned A / D converters 12a and 12b and the pulse shaping circuit 15, the arithmetic unit 13 also calculates an arithmetic result. A display 16 for displaying is connected. Then, the arithmetic unit 13 calculates the magnitude of the unbalance in each of the left and right surfaces existing in the specimen W from the amplitude values of the unbalance signals from the left and right detectors 5a and 5b, as will be described in detail later. From the phase relationship between each unbalanced signal and the rotation reference pulse, the unbalanced direction (angular position) of each of the left and right surfaces is calculated. Then, the calculation results are displayed on the display 16.

Next, a procedure for measuring the magnitude and direction of the imbalance performed by the above-described dynamic balance tester will be described in detail with reference to FIG. The reason why the output of the vibration sensor 5 is A / D-converted and then taken into the calculation unit 13, while the reference position signal (reference pulse) from the laser sensor 6 which is a rotation reference sensor is also taken into the calculation unit 13 as described above. It is as follows. First, a reference function serving as a reference in the X direction and the Y direction is created based on the reference pulse (center in FIG. 2). The reference function in the X direction is a cosine function whose origin is the rising of the reference pulse and whose period is the period of the reference pulse. The reference function in the Y direction is a sine function with the reference pulse as the origin and the cycle of the reference pulse as the cycle. These waveforms are digitally calculated and stored in the arithmetic unit 13.
Since the cycle of the reference pulse fluctuates somewhat in accordance with the rotation of the specimen, the cycle (interval) of the reference pulse observed immediately before is used as the cycle for generating the reference function.

Next, the digital value of the output of the vibration sensor (left side in FIG. 2) taken into the arithmetic unit 13 is multiplied by the above-mentioned reference functions in the X and Y directions, and then averaging (digital filter processing) is performed. Then, the correlation coefficients are calculated separately in the X and Y directions. The correlation coefficient is a value indicating the degree of coincidence between the phase of the measured signal and the phase of the reference signal, and the greater the value, the greater the degree of coincidence.

When the correlation coefficient in the X direction and the correlation coefficient in the Y direction are obtained, the magnitude and direction of the imbalance can be obtained based on these two values. When the magnitude of the correlation coefficient in the X direction and the magnitude of the correlation coefficient in the Y direction are plotted on the XY rectangular coordinates, the resultant vector represents an unbalanced vector (right side in FIG. 2). The magnitude of the combined vector represents the magnitude of the imbalance, and the angle formed by the combined vector and the X axis represents the direction (angle) of the imbalance.

In the apparatus according to the above-described embodiment, it is more preferable to provide a calibration means as shown in FIG. 3 in order to cancel a temporal variation of the measurement circuit. FIG. 3 is a diagram for extracting and explaining a circuit portion from one vibration sensor 5 to the calculation unit 13. A changeover switch 18 is provided at an input portion of the amplifier 11 so that a reference voltage generated by the reference power supply 17 can be input to circuits subsequent to the amplifier 11. The amplifier 11 may drift due to various factors such as an ambient temperature. Further, when the measurement range of the unbalance amount (such as the amplification degree of the amplifier 11) is switched, if the range adjustment is insufficient, the measured value may be different in each range. The calibration means shown in FIG. 3 performs calibration so as to cancel these fluctuation factors by actually measuring a reference voltage.

The calibration is performed in the following procedure. The changeover switch 18 is set to the reference power supply 17 side, and the reference power supply 17 is set so as to generate a predetermined voltage (referred to as E).
Then, the reference voltage value is measured via the amplifier 11 and the A / D converter 12. If the measured value at that time is V, this value should originally match E, so this error is considered to be caused by an unspecified error of the amplifier 11 or the like, and a correction coefficient K = E / V is introduced. .

In the case of an actual unbalance measurement, the changeover switch 18 is measured across the vibration sensor, and the above-described correction coefficient K is added to the measured value of the vibration sensor output (the value after A / D conversion). By multiplying, a measured value in which an error of the amplifier is canceled can be obtained. After that, the unbalance amount is calculated in the same manner as described above.

It is preferable that the calibration using the reference voltage is performed for each measurement range, and the correction coefficients are stored. Then, the error caused by changing the measurement range is canceled. In addition, if the calibration operation is performed not only when the power of the apparatus is turned on, but also as needed, it is possible to always obtain more accurate measured values.

It should be noted that the first in the claims.
The third calculation means is a means realized inside the calculation unit 13 in the above-described embodiment. Further, in the above description, the arithmetic unit 13 is a digital arithmetic device mainly composed of a DSP, but it is needless to say that the arithmetic unit 13 may be realized by a personal computer or the like.

[0020]

In the dynamic balance test apparatus of the present invention, the output of the vibration sensor is immediately converted into a digital signal by digital-to-analog conversion, and is digitally calculated based on the reference position signal from the rotation reference sensor. A digital operation is performed between the reference function in the X direction and the reference function in the Y direction to obtain a correlation coefficient in the X direction and the Y direction, and the magnitude and direction of the unbalance of the specimen are calculated based on the correlation coefficient. As a result, there is little room for an error based on drift or temperature dependence as in an analog circuit, and a highly accurate unbalance amount can be obtained. In addition, since various digital filters can be employed in obtaining the correlation coefficient, not only the accuracy of the result is high, but also the measurement time can be shortened by selecting an optimal processing method.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the device of the present invention.

FIG. 2 is a diagram conceptually illustrating an unbalance calculation method according to the present invention.

FIG. 3 is a diagram showing a preferred embodiment of a calibration process.

[Explanation of symbols]

 1a, 1b: Elongation measuring device 2: Belt 3: Motor 4a, 4b: Spring 5a, 5b: Vibration sensor 6: Laser sensor 11a, 11b: Amplifier 12a, 12b: A / D converter 13: Operation unit 14: Amplifier 15 ... Pulse forming circuit 16 ... Display 17 ... Reference power supply 18 ... Changeover switch W ... Sample M ... Mark

Claims (2)

[Claims] 1. A dynamic balance test apparatus for calculating a magnitude and a direction of an unbalance from a vibration signal detected when a specimen is rotated and a reference position signal of rotation, a vibration sensor for detecting vibration of the specimen. An A / D converter for converting the output of the vibration sensor into a digital signal, a rotation reference sensor for detecting a rotation reference position of the specimen, and an X and Y direction based on the reference signal of the rotation reference sensor. First calculating means for calculating a reference function, and a phase relationship between the X direction and the Y direction based on the output of the A / D converter and the reference function in the X and Y directions calculated by the first calculating means. A dynamic balance test comprising: a second calculating means for calculating the number; and a third calculating means for calculating the magnitude and direction of the unbalance of the specimen from the correlation coefficient in the X and Y directions. apparatus. 2. A method for calculating an unbalance of a dynamic balance test apparatus for calculating a magnitude and a direction of an unbalance from a vibration signal detected when a specimen is rotated and a reference position signal of rotation,
The output from the vibration sensor is A / D converted and fetched as a digital signal, a reference function in the X and Y directions is calculated based on the reference signal from the rotation reference sensor, and the digital signal from the vibration sensor and the reference function are calculated. Between X direction and Y
An unbalance calculation method for a dynamic balance test apparatus, comprising: calculating a correlation coefficient in a direction; and calculating a magnitude and a direction of the unbalance of the specimen based on the correlation coefficient in the X direction and the Y direction.