JPH0454432A - Deciding means for contacting of rotary body and mixing of foreign matter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rotating body such as a motor, in which the contact between a rotating part and a non-rotating part due to the structure and the internal rotation [Prior Art] Conventionally, a stepping motor The human ear is used to detect abnormal noises that occur during rotation to determine whether there is uneven contact between the shaft and the holding part due to a structural defect in the rotor and yoke, or whether there is a foreign object that has entered the joint of the rotating body. It depended on the method. Alternatively, a frequency analysis method was used to analyze the sound waveform (vibration waveform) emitted by the motor, extract features, and make a determination. There are two types: one that listens with the ears and one that detects and analyzes sound wave shapes.

[Problem to be solved by the invention]

However, with conventional judgment methods, the former relies on the sensory test of human hearing, so the judgment criteria are not clear (and there is also the problem that only specific people can make judgments due to differences in individual abilities). Regarding the latter, since the vibration waveform is frequency-resolved, the measurement equipment is large-scale, costly, and takes a long time to measure.Also, the frequency characteristics of the sound do not match the sound quality that can be heard by the ear, making it impossible to perform highly accurate detection. There was a problem.

Therefore, in order to solve the problems of the conventional sensory test using the ear, the high cost of the analyzer, and the low detection rate considering the long fixed time, the present invention establishes a general-purpose judgment method and uses a simple device. The purpose is to be able to make automatic judgments.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a method for determining the presence or absence of contact between rotating bodies and the presence or absence of foreign matter contamination between a rotating body such as a motor bearing and the guide part, or between a rotating body and a rotating part such as an external contact prevention part. Rubbing due to structure within non-rotating parts, or
In the method of detecting contact caused by mixed foreign matter and determining whether there is rubbing or foreign matter contamination, the capacitance between a rotating body and a non-rotating part is measured, and the fluctuation of the capacitance is used to detect contact or foreign matter contamination. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings in the case of a stepping motor. In FIG. 1, in order to measure the capacitance of a stepping motor 1, an electrode 2 is brought into contact with the rotating shaft and an electrode 3 is brought into contact with the outer frame. This electrode measures the motor's capacitance. Since the bearing is a lubricated surface, there is no electrical conductivity, and in the case of a snapping motor, the electrical capacity is dominated between the rotor and yoke.

When the rotating shaft is gradually rotated, the capacitance changes with the rotation angle, as shown in FIG. 2, and becomes approximately several tens of μF. However, if there is a contact object around the rotating body, the capacitance increases (varies) as shown in Figure 2 A and B. On the other hand, the capacitance increases even if there are no foreign objects or the shaft does not come in contact with the rotating body. , it is stable at about several tens of μF and does not fluctuate greatly. Therefore, by setting a threshold value of about ±1 μF, it is possible to detect products with foreign objects and products with shaft pieces.
Measurement is possible when the motor rotates at a constant rate, and to configure the measurement system, all you need is an electrode around the shaft (one that comes into contact with the plan, spring, etc. without adhesive), an electrode for the outer frame, an impedance meter, and a simple comparator. That's fine.

In addition, contact objects and foreign objects that can be detected by the method of the present invention are cases where a rotating object and a non-rotating object are in contact or are very close together, and minute dust etc. cannot be detected compared to the gap.Such small dust This has no effect on the actual rotation of the motor and cannot be a fatal defect.On the other hand, the contact that can be detected by the present invention causes a decrease in torque during rotation, deteriorating the motor characteristics, and cannot become a fatal defect. With other methods, it is currently difficult to classify fatal defects based on the ability to distinguish between the presence and absence of abnormal sounds.In other words, even things that cannot potentially become defects are discarded as defects. ing.

Therefore, the present invention can be said to be an efficient method for detecting defective products.

〔Effect of the invention〕

As described above, according to the present invention, since the determination can be made simply by measuring the capacitance of the rotating body, automatic testing is possible and the need for human sensory testing can be eliminated. Also,
This method eliminates the need for frequency processing of waveforms that would be required using voice recognition technology, is inexpensive, enables real-time measurement, and can be fully used in manufacturing sites. In this case, it is necessary to prepare a vibration-proof table and a sound-proof room in order to be careful about noise and vibration from outside. However, with this method, the object to be measured is the electric capacity of the motor, so as long as the electrodes can be connected, it is possible to It is not affected by the environment (and can be easily implemented under adverse conditions such as manufacturing sites).

[Brief explanation of drawings]

FIG. 1 is a diagram showing the measurement method of the present invention. Figure 2 is a diagram showing the discrimination method when using the method of the present invention. 1...Stepping motor 2---
Rotating shaft electrode 6--・--・Outer frame electrode 4--・Capacitance characteristics

Claims (1)

[Claims] Detects friction due to structures between rotating parts such as motor bearings and the guide part, or between rotating parts and non-rotating parts such as the rotating body and external contact prevention part, or contact due to foreign objects mixed in, and prevents friction and A method for determining the presence or absence of foreign matter contamination, characterized in that the capacitance between the rotating body and the non-rotating part is measured, and the presence or absence of contact or the contamination of foreign matter is determined based on fluctuations in the capacitance. , a method for determining the presence or absence of foreign matter contamination.