JP4812446B2 - Defect detection method for roller bearings by torque monitoring - Google Patents

Description

  The present invention relates to a roller bearing defect detection method based on torque monitoring that detects defects in one or both of a rolling contact surface and a roller of a roller bearing.

2. Description of the Related Art Conventionally, as a method for detecting a defect on a rolling surface of a bearing or a rolling element in a state of a single component, an appearance inspection with a naked eye using a microscope has been performed.
Further, as a bearing defect detection method in a finished product state, a method of vibration inspection using an acceleration pickup or a speed pickup is performed (for example, Patent Document 1).
JP 2000-171351 A

However, in the appearance inspection with the naked eye using the microscope described above, the inspection takes a lot of time and oversight may occur due to human work. Further, in the inspection of a single component, it is impossible to detect a scratch or a burr crimp that occurs during product assembly.
In the vibration inspection, it is possible to detect a relatively large defect, but it is difficult to detect a small defect having a slight catching feeling. In addition, there is a problem that a large defect that locks the rotation causes the vibration value to be small, and may be erroneously determined as a non-defective product.

  The object of the present invention is to accurately detect minute defects existing on the rolling surface of the roller bearing and the roller in the finished product, and to stably detect large defects that lock the rotation. It is another object of the present invention to provide a roller bearing defect detection method by torque monitoring that can be shortened.

According to the present invention, there is provided a roller bearing defect detection method based on torque monitoring, in a roller bearing including an outer ring and a plurality of rollers that roll on the rolling surface of the outer ring, either or both of the rolling surface of the outer ring and the roller. The taper shaft is inserted into the roller array in the roller bearing, and the taper shaft is rotated and the tapered surface is brought into close contact by the wedge effect. A variation in rotational torque of the shaft is detected by a torque sensor, and a defect of the rolling surface or roller is detected by signal processing of a signal detected by the torque sensor.
According to this method, it is possible to accurately detect minute defects existing on the rolling surface and roller of the roller bearing in the finished product, and it is possible to stably detect large defects that lock the rotation, and the time required for inspection is also increased. Can be shortened. That is, high detection performance from a minute defect to a large defect can be obtained. In addition, since the inspection time is short, the defect detection process in the bearing production process can be inlined.

  In the present invention, the signal processing may remove signal components in a predetermined unnecessary frequency band from the signal waveform obtained from the torque sensor by filtering. The signal processing may be performed by performing envelope detection processing and quantifying the defect component by frequency analysis of the signal subjected to the envelope detection processing. Further, the signal processing may be performed by counting pulses. The signal processing may be a method of performing quantification using an effective value.

  According to the present invention, there is provided a roller bearing defect detection method based on torque monitoring, in a roller bearing including an outer ring and a plurality of rollers that roll on the rolling surface of the outer ring, either or both of the rolling surface of the outer ring and the roller. The taper shaft is inserted into the roller array in the roller bearing, and the taper shaft is rotated and the tapered surface is brought into close contact by the wedge effect. Rolling bearings in the finished product are detected by detecting fluctuations in the rotational torque of the shaft with a torque sensor and detecting the defect of the rolling surface or roller by processing the signal detected by the torque sensor. A minute defect existing on a surface or a roller can be detected with high accuracy, a large defect whose rotation is locked can be detected stably, and the time required for detection can be shortened.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of an inspection apparatus used in the roller bearing defect detection method according to this embodiment. The roller bearing 11 to be inspected to which this defect detection method is applied includes a cylindrical shell-type outer ring 12 and a rolling surface 12a that is an inner diameter surface of the outer ring 12 as shown in FIG. This is a shell-type radial bearing including a plurality of rollers 13 arranged along the rolling surface 12a and a retainer 14 that rotatably holds these rollers 13. In this defect detection method, defects in the rolling surface 12 a of the outer ring 12 and the rollers 13 in the roller bearing 11 are detected.

  An inspection apparatus 1 shown in FIG. 1 is inserted into a chuck 2 that grips a roller bearing 11 to be inspected from the outer periphery of an outer ring 12 and an array of rollers 13 in the roller bearing 11 that are disposed opposite to the chuck 2. A taper shaft 3, a motor 4 that rotationally drives the taper shaft 3, a torque sensor 5 that detects fluctuations in the rotational torque of the taper shaft 3, and an analyzer 6 that performs signal processing on signals detected by the torque sensor 5. Is provided. The chuck 2 is supported so as to be movable up and down along the linear slide 8 and is driven up and down by a lifting drive source 7 including a cylinder device or the like. The chuck 2 can be aligned by the alignment mechanism 9. A load cell 10 for monitoring the amount of insertion of the taper shaft 3 into the roller bearing 11 is provided in the vicinity of the taper shaft 3.

  The taper shaft 3 is inserted into the roller bearing 11 held by the chuck 2 as the chuck 2 moves up. The load cell 10 measures the pressure applied to the taper shaft 3 when the taper shaft 3 is inserted, and estimates the insertion amount of the taper shaft 3 from the measured value. When the insertion amount of the taper shaft 3 monitored by the load cell 10 exceeds a certain value, the lift drive source 7 is stopped in response to this. At this time, due to the wedge effect of the taper shaft 3, the roller 13 of the bearing 11 and the outer ring rolling surface 12a are in close contact with each other at the taper shaft 3. In this state, the taper shaft 3 is rotationally driven by the motor 4, and the fluctuation of the rotational torque of the taper shaft 3 is detected by the torque sensor 5. The signal detected by the torque sensor 5 is processed by the analyzer 6 to detect the presence or absence of a defect in the outer ring rolling surface 12a of the roller bearing 11 or the roller 13.

  FIG. 2 shows a block diagram of the analyzer 6. The analyzer 6 includes a preamplifier circuit unit 21 at the front stage and a PLC (programmable logic controller) 22 for analysis at the rear stage. The preamplifier circuit unit 21 performs a filter process for removing a signal component in an unnecessary frequency band from the signal waveform obtained by the torque sensor 5 by the band filter 24, and then amplifies the signal by the amplifier 25. And a second filter circuit 23B that amplifies the signal by an amplifier 27 after performing a filter process for removing a signal component of an unnecessary frequency band from the signal waveform obtained by the torque sensor 5 by the low-pass filter 26. .

  The analyzing PLC 22 includes an envelope detection / frequency analysis processing unit 27, a pulse count unit 28, an effective value calculation processing unit 29, and a determination unit 30.

  The envelope detection / frequency analysis processing means 27 performs envelope detection processing on the signal that has passed through the first filter circuit 23A in the preamplifier circuit unit 21, and performs frequency analysis of the signal subjected to the envelope detection processing to thereby detect a defect component. Quantification is performed. The envelope detection / frequency analysis processing means 27 has an absolute value detection unit 27a, an envelope processing unit 27b, and a frequency analysis unit 27c in this order from the input side, and detects an absolute value of the input signal by the absolute value detection unit 27a. The detected signal is subjected to envelope processing by the envelope processing unit 27b, and the frequency-analyzed signal is subjected to frequency analysis by the frequency analysis unit 27c.

  The pulse counting means 28 performs pulse counting of a signal that has passed through the first filter circuit 23A. The pulse count means 28 has an absolute value detection unit 28a, a crest factor processing unit 28b, and a pulse count unit 28c in this order from the input side. The absolute value detection unit 28a detects the absolute value of the input signal and this detection is performed. The crest factor processing unit 28b performs crest factor processing, and the pulse coefficient of the processed signal is performed by the pulse count unit 28c.

  The effective value calculation processing means 29 calculates the effective value of the signal that has passed through the second filter circuit 23B in the preamplifier circuit section 21, and quantifies the defect component based on the effective value.

  The determination means 30 determines the presence or absence of defects in the roller bearing 11 from the processing results of the envelope detection / frequency analysis processing means 27, the pulse count means 28, and the effective value calculation processing means 29, and outputs a determination signal. is there. The determination unit 30 includes a normal product determination unit 30 a and a locked product determination unit 30 b, and the normal product determination unit 30 a corresponds to the outputs of the envelope detection / frequency analysis processing unit 27 and the pulse count unit 28. In accordance with a predetermined determination criterion, a normal product is determined. The lock product determination unit 30b determines the lock product according to a predetermined reference from the processing result of the effective value calculation processing unit 29.

  Table 1 shows the function names of the signal processing means 27 to 29 in the analyzing PLC 22 in the analyzer 6, the contents thereof, and the inspection items in a contrasting manner.

  That is, the determination means 30 detects a sense of grief due to a minute defect by determining “envelope detection + FFT” performed by the envelope detection / frequency analysis processing means 27 and determining the pulse count performed by the pulse count means 28. And the detection of the effective value calculation result performed by the effective value calculation processing means 29 detects a very large wrinkle that causes the roller bearing 11 to lock without rotating.

3 to 5 are graphs showing specific inspection results obtained by the above-described defect detection method. Of these, FIG. 3 shows the inspection result for the presence or absence of a sense of ghost based on the data of the envelope detection processing, FIG. 4 shows the result of the examination for the presence or absence of sensation based on the data of the pulse count, and FIG. Each test result is shown. This inspection was performed under the following measurement conditions.
Applied pressure: 3N
Taper shaft taper angle: 0.0035 °
Taper shaft rotation speed: 300rpm
Measurement chuck advance speed: 30 mm / sec
Measurement time: 0.51 sec
Details of determination: (1) Envelope detection + FFT (carrier band 120-320 Hz, repetition frequency 23 Hz)
(2) Pulse count
(3) Effective value

  In the graph of the measurement result of “envelope detection + FFT” shown in FIG. 3, a product with a moderate feeling of required accuracy is a product having a horizontal axis of 3.0 or more in the graph. If the NG (defective) level is determined, 100% NG determination is made, and it can be seen that the required accuracy is satisfied. It can also be seen that a product with a low degree of harshness can be detected to some extent.

  According to the graph of the measurement result with the pulse count shown in FIG. 4, when comparing the determination of a product with a moderate feeling of harshness with the determination by “envelope detection + FFT”, the fluidized product and the measured value are close to each other. If you can see.

  In the graph of the result of measuring the presence / absence of the locked product in the effective value determination shown in FIG. 5, the determination value of “envelope detection + FFT” and the pulse count are the same level as the OK product (good product), but the effective value is OK. The value is 3 to 10 times that of the product.

  Based on the above results, the detection of a sense of grief due to a minute defect is based on the “envelope detection + FFT” determination, combined with the pulse count determination, and if a serious NG that does not rotate and lock is performed by the effective value determination, It was confirmed that accurate defect detection was possible.

  Therefore, in the roller bearing defect detection method based on torque monitoring according to the present invention, it is possible to accurately detect minute defects existing on the outer ring rolling surface 12a of the roller bearing 11 and the roller 13 in the finished product state. . In addition, it is possible to stably detect a large defect that is difficult to detect in the vibration inspection of the conventional example and whose rotation is locked. Furthermore, since the inspection time is shorter than in the case of visual inspection with a single component by visual observation in the conventional example, it is possible to perform an in-line 100% automatic inspection.

(A) is a schematic block diagram of the test | inspection apparatus used for the defect detection method of the roller bearing by torque monitoring concerning one Embodiment of this invention, (B) is the elements on larger scale which show the relationship between the bearing and a taper shaft. . It is a block diagram of the analyzer in the inspection device. It is a graph of the measurement result by "envelope detection + FFT" determination in the said defect detection method. It is a graph of the measurement result by pulse count determination in the defect detection method. It is a graph of the measurement result by the effective value determination in the said defect detection method. It is sectional drawing which shows an example of the roller bearing used as the test object of the defect inspection method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Tapered shaft 5 ... Torque sensor 6 ... Analyzer 11 ... Roller bearing 27 ... Envelope detection / frequency analysis processing means 28 ... Pulse count means 29 ... Effective value calculation processing means 30 ... Determination means

Claims (5)

In a roller bearing provided with an outer ring and a plurality of rollers rolling on the rolling surface of the outer ring, a method for detecting a defect in one or both of the rolling surface of the outer ring and the roller,
Insert a taper shaft into the roller array in the roller bearing, rotate the taper shaft with the tapered shaft and the rolling surface in close contact with each other by the wedge effect, and use a torque sensor to measure the fluctuation in rotational torque of the taper shaft. A method for detecting a defect of a roller bearing by torque monitoring, wherein the defect of the rolling surface or the roller is detected by detecting and processing a signal detected by a torque sensor.   2. The roller bearing defect detection method according to claim 1, wherein, as the signal processing, a signal component of a predetermined unnecessary frequency band is removed from the signal waveform obtained from the torque sensor by filtering.   3. The roller bearing defect detection method according to claim 1 or 2, wherein, as the signal processing, an envelope detection process is performed, and a defect component is quantified by frequency analysis of the signal subjected to the envelope detection process. .   3. The roller bearing defect detection method according to claim 1, wherein the signal processing includes torque monitoring for counting pulses.   3. The roller bearing defect detection method according to claim 1, wherein the signal processing is quantified by an effective value as torque processing.

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