JP4299949B2 - Method and apparatus for detecting slippage between roller shaft and bearing of conveyor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a slip detection method and a detection device between a roller shaft of a conveyor and a bearing that detect slippage between the shaft and the inner ring, which is generated by loosening between the shaft and the inner ring of the bearing.
[0002]
[Prior art]
Generally, in various types of bearings, tightening loosening may occur between the shaft and the bearing due to poor mounting of the bearing or an excessive load during operation. When this looseness occurs, slippage occurs between the shaft and the bearing, which causes seizure in the bearing due to frictional heat and contamination of foreign matter. And a crack generate | occur | produces on a rolling surface and a rolling element, and it may lead to damage of a bearing.
[0003]
On the other hand, as a method for detecting an abnormality occurring on a rolling surface of a bearing or a rolling element, detection by a vibration method has been used in addition to human hearing and tactile sense by hand.
[0004]
However, in these conventional methods, when the abnormal impact sound generated from the vicinity of the bearing is low, it is often difficult to discriminate from other noises. In addition, when an abnormal noise is observed, it is usually after a scratch or the like has already occurred on the rolling surface of the bearing.
[0005]
[Problems to be solved by the invention]
In view of such a conventional situation, an object of the present invention is to provide a method and a detection device for easily and reliably detecting slippage between a shaft and a bearing that cause damage to the bearing.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the feature of the slip detection method between the roller shaft of the conveyor and the bearing according to the present invention is provided with a roller shaft of the conveyor and a bearing that pivotally supports the shaft, and an acoustic sensor from the vicinity of the bearing The acoustic signal is received by, and among the signal components in the acoustic signal, the intensity of the component at the frequency corresponding to the rotational speed of the shaft is continuously monitored during the operation of the conveyor, whereby the shaft and the inner ring of the bearing are The purpose of this is to detect slippage between the inner ring and these shafts, which is caused by loose tightening between them. In the present embodiment, a tapered jig is inserted between the shaft and the inner ring.
[0007]
According to the experiments by the inventors, when slip occurs between the shaft and the bearing, the intensity of the component at the frequency corresponding to the rotational speed of the shaft among the signal components in the acoustic signal generated from the vicinity of the bearing becomes high. It has been found. Therefore, the slip can be detected at an early stage by monitoring this intensity.
[0008]
On the other hand, the characteristic configuration of the slippage detection device between the roller shaft and the bearing of the conveyor according to the present invention includes a roller shaft of the conveyor, a bearing that pivotally supports the shaft, and an acoustic sensor that receives an acoustic signal from the vicinity of the bearing. The shaft rotation number detecting means for detecting the number of rotations of the shaft and the frequency analysis means for analyzing the frequency in the acoustic signal, and the rotation of the shaft detected by the shaft rotation number detecting means among the frequency components of the acoustic signal. Strength detecting means for continuously measuring the strength of the component at the frequency corresponding to the number during the operation of the conveyor is provided, and between the inner ring of these shafts generated by loosening between the shaft and the inner ring of the bearing. It is to detect slippage.
[0009]
【The invention's effect】
As described above, according to the present invention, it is only necessary to monitor the “intensity of the component at the frequency corresponding to the rotational speed of the shaft” in the acoustic signal, so that it is less susceptible to noise and reliably slips between the shaft and the bearing. Can now be detected. In addition, since it is easy to limit the monitor information, the apparatus itself can be easily configured, and slip detection can be easily performed.
[0010]
Other objects, configurations and effects of the present invention will become apparent in the section of the embodiment of the present invention shown below.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a longitudinal sectional view in the vicinity of a bearing that is a detection target of the present invention, and is used when, for example, a roller shaft such as a conveyor is pivotally supported. Here, in the shaft end portion structure 1, the shaft 2 is rotatably received by the bearing 3, and the bearing 3 is supported by the bearing housing 4.
[0012]
The shaft 2 has a small diameter portion 2 a on the end side and an intermediate large diameter portion 2 b, and the small diameter portion 2 a is fastened and fixed to the bearing 3 by a jig 5. Here, the tapered surface 5 a of the jig 5 has a smaller diameter toward the end portion side of the shaft 2, similar to the inner ring inner surface 8 a of the inner ring 8 of the bearing 3. Then, a lock washer 7 is externally fitted to the end of the inner ring 8, and a nut 6 is screwed into the threaded portion 5b and tightened. The jig 5 is forced to bite between the shaft 2 and the shaft 2 and the inner ring 8 to prevent relative rotational slippage.
[0013]
A plurality of rolling elements 9 are arranged in the circumferential direction over two rows between the inner ring 8 and the outer ring 11 located on the outer periphery thereof. The cage 10 positions the rolling elements 9 and prevents contact between the rolling elements 9. The inner ring 8 is supported so as to be rotatable relative to the outer ring 11.
[0014]
The bearing housing 4 is fixedly supported on the basis of the outer ring 11 of the bearing 3. A hole is formed in the end of the bearing box 4 and is closed by a lid 4a, and an acoustic sensor 21 is attached to the lid 4a. The bearing box 4 is manufactured as a casting or the like, and an acoustic signal (AE) resulting from relative rotation between the small diameter portion 2 a and the jig 5 is received by the acoustic sensor 21 due to loosening of the nut 6.
[0015]
FIG. 2A is a block diagram of a detection apparatus 20 for performing the detection method of the present invention. The detection device 20 receives an acoustic signal generated between the shaft 2 and the jig 5 by an acoustic sensor 21, amplifies it by an amplifier 22, records it by a waveform recording device 23, and records a fast Fourier signal by a frequency analysis device 24. A frequency spectrum is obtained by transformation (FFT).
[0016]
According to the experiments by the inventors, the acoustic signal waveform when the bearing is not loose is as shown in FIG. 5, and the envelope waveform shown in FIG. The frequency spectrum shown in (b) is obtained. From these examples, it can be seen that when there is no looseness, the envelope waveform has little fluctuation and the frequency spectrum is generally flat.
[0017]
On the other hand, as shown in FIG. 4, the envelope waveform shown in (a) of the acoustic signal waveform in the case where the bearing is loosened generally fluctuates. In addition, the frequency spectrum after the FFT processing shown in (b) is high as indicated by an arrow at a certain characteristic frequency in the low frequency region.
[0018]
As a result of investigating the relationship between the characteristic frequency f0 at which the frequency spectrum shown in FIG. 3 is locally increased and the rotational speed of the shaft, it was found that the characteristic frequency f0 is substantially equal to the frequency corresponding to the rotational speed of the shaft 2. Since the slip between the shaft 2 and the jig 5 is intermittently generated, a relative rotation equal to the rotational speed of the shaft 2 is generated between them, which corresponds to the rotational speed of the shaft 2. It is inferred that frequency AE has occurred.
[0019]
Next, as a second embodiment of the present invention, a detection device 30 that continuously monitors characteristic frequencies will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the member similar to the said embodiment.
[0020]
The acoustic signal from the acoustic sensor 21 is A / D converted by the A / D converter 25 a after being amplified by the amplifier 22 and processed by the personal computer 26. The rotation speed of the shaft 2 is detected by a rotation speed detection element 27a that magnetically or optically captures the mark on the shaft 2 or a rotation control device 27b that controls driving of the entire conveyor system. The signals of the rotation speed detecting element 27a and the rotation control device 27b which are these rotation detecting means are A / D converted by the A / D converter 25b and used for determining the characteristic frequency for monitoring in the personal computer 26.
[0021]
In the personal computer 26, the envelope waveform of the input acoustic signal is subjected to FFT conversion by the FFT means 26a, and a frequency spectrum is obtained. In the intensity monitoring means 26b equivalent to the intensity detecting means, the characteristic frequency is determined based on the signal from the previous rotation detecting means, and the intensity of the frequency component at the characteristic frequency is monitored. When the frequency component at this characteristic frequency exceeds a certain level of intensity, an alarm is issued to detect the looseness of the shaft.
[0022]
Finally, the possibilities of other embodiments of the invention are listed.
In the above embodiment, the present invention has been described for a bearing of a conveyor. In the above embodiment, the inner ring of the bearing is on the rotation side and the shaft itself is rotated. However, the outer ring of the bearing may be the rotating side and the shaft itself may be the fixed side.
[0023]
In the above embodiment, the present invention has been described for the roller bearing. However, the present invention can be implemented not only for ball bearings but also for bearings using sliding bodies that do not use rolling elements such as rollers and balls.
[0024]
In addition, the code | symbol entered in the term of the claim is only for the convenience of contrast with drawing, and this invention is not limited to the structure of an accompanying drawing by this entry.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view in the vicinity of a bearing to be detected according to the present invention.
FIG. 2A is a block diagram of a detection apparatus for carrying out the detection method of the present invention, and FIG. 2B is a block diagram of a detection apparatus showing another embodiment.
FIG. 3 is a diagram showing a relationship between slip between a shaft and a bearing and signal intensity at a characteristic frequency.
FIGS. 4A and 4B are acoustic signal waveforms when a bearing is loosened, where FIG. 4A is an envelope waveform, and FIG. 4B is a waveform showing a frequency spectrum after FFT processing.
FIGS. 5A and 5B are acoustic signal waveforms when the bearing is not loosened, where FIG. 5A is an envelope waveform, and FIG. 5B is a waveform showing a frequency spectrum after FFT processing;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shaft end structure 2 Shaft 2a Small diameter part 2b Large diameter part 3 Bearing 4 Bearing box 4a Lid 5 Jig 5a Tapered surface 5b Screw part 6 Nut 7 Washer 8 Inner ring 8a Inner ring inner surface 9 Rolling element 10 Cage 11 Outer ring 20 Detector DESCRIPTION OF SYMBOLS 21 Acoustic sensor 22 Amplifier 23 Waveform recording device 24 Frequency analyzer 25a, 25b A / D converter 26 Personal computer 26a FFT means 26b Intensity monitor means 27a Rotation speed detection element 27b Rotation control device 30 Detection apparatus

Claims (3)

  A roller shaft of the conveyor and a bearing that pivotally supports the shaft, and an acoustic signal is received from the vicinity of the bearing by an acoustic sensor. Among signal components in the acoustic signal, a component at a frequency corresponding to the number of rotations of the shaft. The roller shaft and the bearing of the conveyor which detects the slip between the shaft and the inner ring caused by loosening between the shaft and the inner ring of the bearing by continuously monitoring the strength of the conveyor during the operation of the conveyor Slip detection method between.   The method for detecting slippage between a roller shaft and a bearing of a conveyor according to claim 1, wherein a tapered jig is interposed between the shaft and the inner ring.   A roller shaft of the conveyor, a bearing that pivotally supports the shaft, an acoustic sensor that receives an acoustic signal from the vicinity of the bearing, a shaft rotational speed detection means that detects the rotational speed of the shaft, and frequency analysis in the acoustic signal A frequency analysis means for performing strength measurement for continuously measuring the strength of a component at a frequency corresponding to the rotational speed of the shaft detected by the shaft rotational speed detection means among the frequency components of the acoustic signal during operation of the conveyor A slip detection device between a roller shaft of a conveyor and a bearing, which is provided with detection means and detects slip between the shaft and the inner ring caused by loosening between the shaft and the inner ring of the bearing.

Images