Bearing preloading can effectively prolong the service life of bearings, and also can improve the operation accuracy and rigidity of bearings, and reduce the deformation. As a high progress bearing, YRT turntable bearing also needs to apply certain preload during installation. However, if the preload cannot be adjusted and perfected, it will accelerate the deformation and failure of the bearing. How to determine the preload of YRT turntable bearing?
1、 Determination of bearing preload by measuring rotation torque
With spring scale or simple dynamometer, fix the bearing and rotating shaft well during assembly, and ensure that the shaft can rotate, and then put the spring scale or simple dynamometer shaft. The spring scale is used to apply tension along the tangent direction of the shaft, and the inner ring and the shaft rotate together. When the reading is in a stable state, it is the final measurement result. The pre-tightening torque value of the bearing on the spindle is obtained by multiplying the measured force and the distance between the tangent line and the shaft center.
The bearing used in pairs has the requirement of friction torque. When the bearing form, internal parameters, and lubrication mode are certain, the friction torque of the bearing has a certain corresponding relationship with the axial load, so the determination of preload can refer to the friction torque of the bearing. Therefore, through the calculation of the friction torque of pairs of bearings bearing preload, the calculation results are compared with the actual measured value of friction torque to determine whether the internal preload of bearing meets the requirements.
2、 Pre measurement of bearing preload
Before the bearing is installed, the bearing is pre-installed with a test system similar to the actual installation. The bearing is installed in the mechanism, and the axial preload required by conversion is applied to measure the actual bearing distance. The measured value is the actual size value required in the assembly after the bearing is applied with preload, which includes the actual distance of the bearing and the clearance adjustment size after the bearing is applied with the preload. The length of the spacer sleeve is processed according to the actual distance of the bearing.
In the actual installation process, strictly control the fit between the bearing bore and the shaft, so that the inner ring of the bearing can not be loose at the shaft neck, but also move along the axial direction flexibly. When assembling the inner and outer rings, it is appropriate to fit the thumbs of both hands at the shaft journal and bearing seat hole. Then, the actual assembly size can be ensured by adjusting the sleeve size and outer bearing cover size. If necessary, the adjusting gasket with a fixed size can be added during the size adjustment to ensure that the value of bearing preload is close to the predicted value.
3、 Measurement and control method of bearing deformation
The relationship between the friction torque and axial load of the bearing is measured in advance. The bearing is placed on the circular seat. Through formula conversion, a load equal to the preload can be applied to the inner ring of the bearing by gravity or spring pressure control. After the bearing bears the force, the axial dimension differences △ K1 and △ K2 between the inner and outer rings are measured with a lever dial indicator. When assembling bearings, the preload of each assembled transmission shaft bearing shall be inspected with a special dial indicator. If the applied preload is insufficient, the washer can be added for adjustment to fix the clearance size of the bearing, so as to ensure that the preload is within the fixed range.
4、 Determination of bearing preload with a constant torque wrench
In order to eliminate the clearance between the inner and outer rings of the bearing, the bearing which is fixed axially by the nut can compress the inner ring of the bearing axially by twisting the nut to achieve the goal of bearing preloading. This method is a general method with simple structure and strong applicability, so the preload of preloading bearing is easy to control, and the defect is that there is no quantitative data. However, the preload can be adjusted by measuring the final assembly axial size and adding an appropriate gasket. In order to improve production efficiency and assembly accuracy, a constant torque wrench is usually used to complete the assembly. The main characteristics of a constant torque wrench are: can set the torque, and the torque is adjustable. The constant torque wrench can be used for both initial tightening and final tightening. Its use is to adjust the torque first and then tighten the bolts. In the process of bearing assembly, preassembly can be carried out to obtain the tightening torque required by the preload, and then the assembly can be carried out.
5、 Using a sensor to determine bearing preload
In the assembly process with high requirements, the measurement and control can be realized with the help of sensors. With the rapid development of modern sensor technology, the measurement becomes more and more simple. In the process of bearing assembly, a torque sensor can be selected. The torque sensor is a special strain gauge which is pasted on the elastic shaft with strain glue and forms a strain bridge. The electric signal of the elastic shaft under torsion can be measured by providing current to the strain bridge. After the strain signal is amplified, it is converted into a frequency signal proportional to the torsional strain. The obtained signal can be processed by relevant instruments or computers to display the torque value. Referring to the previous installation method, a fixed shaft rotating bearing seat was measured. Using the special mechanical fixture with a torque sensor, the bearing body rotates with the measuring machine driven by the driving equipment, and the reaction torque value of the fixture can be measured, that is, the bearing preloading torque value. The common drive motor can be used as a driving device to provide power.
How to determine the preload of YRT turntable bearing, in addition to the above methods, for the determination method of bearing preload, there is actually a method based on the experience of technical workers. This method mainly depends on the perception of resistance moment and bearing rotation flexibility of workers' hands. It is very simple for experienced people, but the work efficiency is low, and the labor intensity is large, so it is not suitable for high-precision YRT turntable bearing.
Luoyang Tedin Bearing Co., Ltd. after years of technical research and development and improvement, the YRT turntable bearing produced by our company has been put into use in various high-precision CNC turntables, and can also provide technical services. If necessary, you can leave a message on our website or call our customer service hotline for a detailed consultation.
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