JPH0261700B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for detecting the amount of preload applied to a rolling bearing for various purposes.

Rolling bearings are often used with an appropriate clearance under operating conditions, but
Depending on the purpose of use, the bearing may be used with internal stress generated in advance so that a negative clearance is created when the bearing is assembled. Therefore, management of the magnitude of preload becomes an important issue. If the preload is too large, it is likely to cause an increase in frictional moment, abnormal heat generation, and shortened fatigue life.On the other hand, if the preload is too small, it may easily cause slippage between the rolling elements and the raceway. It is important to apply an appropriate preload.

Methods for controlling and detecting this preload include: (1) A method of tightening and using a combination bearing whose preload has been adjusted in advance.

(2) A method of adjusting the dimensions of spacers and shims without using a combination bearing.

(3) Method using coil springs and disc springs.

(4) Method of measuring the starting friction moment of a bearing.

(5) Method of measuring nut tightening torque.

(6) A method for measuring the amount of axial displacement of a bearing.

However, these conventional methods have the following drawbacks.

Methods (1) and (2) can control the amount of preload with relatively high accuracy, but in the case of (1), the dimensions of the shaft and bearing box that fit into the bearing will affect the dimensional accuracy of the shaft and bearing box. If the shape or shape is bad, the preload will not reach the specified value. Also (2)
This method is affected by the manufacturing accuracy of the spacer and shim, and may exceed a predetermined value due to deformation of the spacer during preload loading. Method (3) allows the amount of preload to be kept almost constant regardless of the relative position of the bearings, but it requires a clearance between the bearings on one side and cannot be used when rigidity is required.

Method (4) is often used for tapered roller bearings, but if the method of measuring the starting friction moment is poor, the variation will be large. In method (5), the variation is small when the tightening torque is large, but the error becomes large when the torque is small. With method (6), it is often difficult to accurately measure displacement with the bearing installed in the machine. In addition, methods (1), (2), and (3) above, which can manage preload with relatively high accuracy, have drawbacks such as the inability to easily check whether the actual predetermined preload has been applied after the bearing is assembled. It was hot.

The present invention has been made to eliminate the above-mentioned drawbacks, and is intended to apply vibration to a rolling bearing to be measured or a member directly or indirectly engaged with the rolling bearing to be measured, or to mainly apply vibration to a rolling bearing to be measured while applying vibration. This is a method of measuring the resonance frequency that changes depending on the magnitude of the spring constant of the spring constant, and detecting the amount of preload based on the relationship value between the amount of preload and the resonance frequency, and a device that embodies this method.

Next, one embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a vibrator for adding vibration to the rolling bearing 11 to be measured, the bearing box 12, the shaft 13, etc., and an electrodynamic type vibrator is usually used. In order to excite this exciter 1, an excitation signal generator 2 and an amplifier 3 for amplifying the pulse wave or random wave transmitted from the excitation signal generator 2 and inputting the amplified wave to the exciter 1 are provided. It is provided. 4 is a speed or acceleration sensor, in this example,
It is integrated with the vibration exciter 1. The signal obtained by this speed or acceleration sensor is amplified by an amplifier 5, and the amplified signal is input to a frequency analyzer 6, such as a FET (Fast Fourier Transform) analyzer.

The device described above is used to measure the resonant frequency of the object to be measured and to detect the amount of preload on the rolling bearing to be measured, but if a suitable vibrator is not available, a small hammer or string can be used. It is also possible to directly or indirectly hit the object to be measured with a suspended small object or the like.

Also, the installation position of the speed or acceleration sensor is
In the above embodiment, it is attached to the shaft end, but it can also be attached to the bearing box, other spacers, front cover, etc. If it is attached to a non-rotating part, it can measure the resonance frequency while the shaft is rotating. , it is also possible to detect the preload of the rolling bearing to be measured.

In the above device, the rolling bearing to be measured 11
The tightening nut 14 is rotationally displaced in order to increase the preload amount, the shaft 13 to which the rolling bearing 11 to be measured is attached is vibrated by the vibrator, and the signal detected by the speed or acceleration sensor 4 is transmitted to the amplifier. 5 and this signal is analyzed by a frequency analyzer 6 to detect the resonant frequency of the rolling bearing to be measured. This device tightens the nut 1
FIG. 2 shows a detected resonance frequency corresponding to the rotation angle of No. 4. This figure 2 shows the detection results of the angular ball bearing (inner diameter 120 mm) shown in figure 1, but depending on the tightening rotation angle of the nut,
That is, it can be seen that the resonant frequency changes as the preload increases. The reason for this change is that the load range of a rolling bearing changes depending on the magnitude of the load it receives, and the deformation of the rolling contact part of the bearing is nonlinear, so the spring constant of the bearing changes depending on the bearing load. Conceivable.

Figure 3 shows the relationship between the preload amount of the tapered roller bearing and the resonance frequency in a device incorporating two tapered roller bearings with an inner diameter of 95 mm, as determined by the detection device shown in Figure 1. It can also be seen that as the preload amount increases, the resonant frequency increases.

If the preload is increased in this way, the resonant frequency will increase, so by calculating the relationship between the preload amount and the resonant frequency using the finite element method, etc., it is possible to detect the preload amount from the resonant frequency. .

Furthermore, even if the relationship between the preload amount and the resonant frequency is not determined by calculation, if an appropriate preload state is created through experience or conventional preload setting methods, the resonant frequency under that state can be used to set the preload.

In the above embodiment, the resonant frequency was measured using a frequency analyzer, but if the relationship value between the preload amount and the resonant frequency is stored in advance in the computer, the preload can be determined by the computer based on the magnitude of the resonant frequency. It is also possible to read out the size.

In addition, if the resonant frequency is affected by installing a speed or acceleration sensor because the mass of the object to be measured or the shaft to be engaged is small, etc., use a non-contact displacement meter as the sensor, or use a microphone. Acoustic detectors such as

By carrying out the method of the present invention and using the device of the present invention, the amount of preload on a rolling bearing can be controlled more accurately than when using the conventional method, thereby preventing heat generation, seizure, and short life due to excessive preload. ,
Alternatively, it is possible to prevent insufficient rigidity, poor rotation accuracy, etc. due to excessive preload.

Furthermore, if the method of the present invention is added to the conventional preload management method, the magnitude of the preload can be confirmed after the rolling bearing is installed in an actual machine or device, thereby improving the accuracy of preload setting.

Moreover, the magnitude of the preload in the operating state of the rotating shaft can also be known by this method.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a device showing an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between the preload amount and the resonance frequency of the combination angular ball bearing according to the rotation angle change of the tightening nut shown in FIG. FIG. 3 is a diagram showing the relationship between preload amount and resonance frequency when two tapered roller bearings are used in combination. Explanation of the symbols: 1 is an exciter, 2 is an excitation signal generator, 3 is an amplifier, 4 is a speed or acceleration sensor,
5 is an amplifier, 6 is a frequency analyzer, and 11 is a rolling bearing to be measured.

Claims (1)

[Scope of Claims] 1. Vibrating or applying vibration to either a rolling bearing to be measured incorporated in a machine or a device, or a shaft or a bearing box that engages with the rolling bearing, or while applying vibration, mainly to the rolling bearing. A method of detecting the resonant frequency, which changes depending on the magnitude of the spring constant, and detecting the preload amount of the rolling bearing from the predetermined relationship between the preload amount of the rolling bearing and the resonant frequency. 2. A vibrator for vibrating the rolling bearing to be measured or a member such as a shaft or bearing box that engages with the rolling bearing, an excitation signal generator for exciting the vibrator, and the vibrator. an amplifier that amplifies a signal transmitted from a signal generator; a speed sensor or acceleration sensor provided integrally with or separately from the vibrator; and an amplifier that amplifies a signal detected by any of the sensors; A preload amount detection device for a rolling bearing that includes a frequency analyzer that analyzes the signal amplified by this amplifier and detects the amount of preload based on the relationship value between the amount of preload and the resonance frequency based on the detected resonance frequency.