JPS59188535A - Method and device for detecting pre-load amount of boll-and-roller bearing - Google Patents

Abstract

PURPOSE:To control a pre-load amount precisely on the basis of the relational value between the pre-load amount and a resonance frequency by measuring the resonance frequency while oscillating a boll-and-roller bearing to be measured or a member which engages said ball-and-roller bearing directly or indirectly. CONSTITUTION:A pre-load amount detector is provided with an exciter 1 which oscillates the bearing 11 to be measured, a bearing box 12, or shaft 13, etc. Then, a clamping nut 14 is rotated and displaced in order to increase the pre- load amount of the ball-and-roller bearing 11 to be measured, and the shaft 13 to which the ball-and-roller bearing 11 to be measured is fitted is excited by the exciter; and a signal generated by the detection of a speed or acceleration sensor 4 is amplified by an amplifier 5, and analyzed by a frequency analyzer 6 to detect the resonance frequency of the ball-and-roller bearing to be measured. Then, the pre-load amount is controlled precisely on the basis of the relational value between the pre-load amount and resonance frequency.

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, internal stress may be generated in advance to create a negative clearance when the bearing is assembled. When a rolling bearing is used under preload, managing the amount of preload becomes an important issue. For example, 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 is likely to cause slippage between the rolling elements and the raceway surface, etc. It is important to apply an appropriate preload depending on the situation.

The preload management and detection methods are: (1) A method of tightening and using a combination bearing whose preload has been adjusted in advance.

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

(3) Method of using coil springs and disc springs.

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

(5) Method for 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. Furthermore, method (2) 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 a method often used for tapered roller bearings, but if the method for measuring the starting friction moment is poor, the variation will be large. In method (5), there is little variation in tightening when the torque is large, but the error becomes large when the torque is small. Methods (11, (2), and (3)) above, which manage preload with high accuracy (6), cannot easily check whether a predetermined preload has actually been applied after the bearing is installed, etc. There was a drawback.

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 l, an amplifier 3 as a second excitation signal generator is provided. Reference numeral 4 denotes a speed or acceleration sensor, which is integrated with the vibrator 1 in this embodiment. The signal obtained by this speed or acceleration sensor is amplified by an amplifier 5, and the amplified signal is sent to a frequency analyzer 6, e.g.
(Fast Fourier Transform)
configured to be input to the 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.

In addition, the speed or acceleration sensor is installed at the end of the shaft in the above embodiment, but it can also be installed at the bearing box, other spacers, front cover, etc., or it can be installed at the non-rotating part. For example, measure the resonance frequency during shaft rotation,
It is also possible to detect the preload of the rolling bearing to be measured.

In the above device, the rolling bearing 11 to be measured is vibrated by a vibration exciter, the signal detected by the speed or acceleration sensor 4 is amplified by the amplifier 5, this signal is analyzed by the frequency analyzer 6, and the rolling bearing to be measured is The resonant frequency of the bearing can be detected. This device detects the resonance frequency according to the rotation angle of the tightening nut 14, and is shown in FIG. 2. This figure 2 shows the detection results of the angular ball bearing (inner diameter 120 mm) shown in figure 1, and it can be seen that the resonance frequency changes depending on the tightening rotation angle of the nut, that is, as the preload increases. .

The reason for this change is thought to be that the load weight of a rolling bearing changes depending on the magnitude of the load it receives, and that 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. .

It can be seen from this figure that the resonant frequency increases as the amount of preload 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. .

Also, even if you do not calculate the relationship between the preload amount and the resonant wave number,
If an appropriate preload condition is created through experience or conventional preload setting methods, the resonance frequency under that condition can be used to set the preload.

In the above embodiment, the resonant frequency was measured using a frequency analyzer, but if the relationship between the preload amount and the resonant frequency is stored in advance in the computer, the preload can be measured by the computer based on the magnitude of the resonant wave number. The method of the present invention allows reading out the magnitude of the resonance frequency, and in cases where the resonance frequency is affected, a non-contact 1WR displacement meter can be used as a sensor, or an acoustic detector such as a microphone can be used. By carrying out this process, and using the device of the present invention, the amount of preload on a rolling bearing can be controlled more accurately than when using conventional methods, and can prevent heat generation, seizure, short life, or under-preload due to excessive preload. This can prevent insufficient rigidity, poor rotational accuracy, etc.

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

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 invention, and FIG.
The figure is a diagram showing the relationship between the preload amount and resonance frequency of the angular ball bearing according to the change in rotation angle of the tightening nut in Figure 1. Figure 3 is an explanation of the tapered roller shaft code. 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, 11 is a rolling bearing to be measured Patent applicant: NSK Co., Ltd.

Claims (1)

[Scope of claims] A method of detecting the resonant frequency that changes depending on the spring constant of the rolling bearing, and detecting the preload amount of the rolling bearing from the predetermined relationship between the preload t of the rolling bearing and the resonance frequency. (2) Rolling bearing to be measured or a vibrator for vibrating a member such as a shaft or a bearing box that engages the rolling bearing, and an excitation signal generator for exciting the vibrator;
an amplifier that amplifies and amplifies the signal transmitted from the excitation signal generator; a speed sensor or an acceleration sensor provided integrally with or separately from the excitation machine; and a signal detected by any of the sensors. A preload amount detection device for a rolling bearing that includes an amplifier to amplify and a frequency analyzer to analyze the signal amplified by the amplifier, and detects the amount of preload based on the relationship between the preload amount and the resonance frequency based on the detected resonance frequency. .