There are two most common ways to replace INA bearings: one is to directly heat INA bearings with acetylene oxygen; the other is to use oil immersion heating for small INA bearings to achieve thermal expansion and expand the inner diameter of INA bearings for assembly. These methods have been widely used in long-term equipment maintenance, and basically satisfy and solve the INA bearing assembly problem in equipment maintenance. However, these two methods are difficult to determine whether the temperature value of the heated area of u200bu200bthe INA bearing is uniform during the heating process. Because the traditional acetylene oxygen heating is a single gas burner, and the heating process is only based on experience, it is difficult to grasp how much the temperature of the heated INA bearing is appropriate. If the temperature is too high, it will anneal the INA bearing and reduce the mechanical performance of the INA bearing; if the temperature is too low, the thermal expansion value is not enough, and it is difficult to assemble. In equipment repairs, the repairman sometimes has to take down the INA bearings and install them again because of insufficient heating of the INA bearings, which increases the labor intensity. For this reason, we propose a new method to change the traditional heating assembly of INA bearings.

　　 1. Use electric heating instead of acetylene oxygen heating. The plane electric furnace is designed into a cylindrical electric furnace, named INA bearing electric heater. According to different INA bearing inner diameters, it can be designed into INA bearing electric heaters of different powers and specifications (the best applicable range is INA bearing inner diameter φ300mm/ above). This kind of heating device has the following advantages: uniform and stable heat radiation, no smoke and dust on the surface of the heated INA bearing, clean and clean, and easy to measure and control the temperature of the INA bearing.

　　2. Use an infrared thermometer to monitor the temperature of the heated INA bearing surface. The heating value of INA bearing assembly is generally controlled at 100℃～120℃. Within this temperature value, the thermal expansion value of INA bearing steel is the largest, which is convenient for INA bearing assembly. This temperature value will not change the mechanical performance of INA bearing, and its reliability is high.

　　 In summary, INA bearing electric heater is superior to traditional acetylene oxygen heating, and it is an effective method to improve INA bearing assembly accuracy and work efficiency, and reduce labor intensity. 1. A way to improve the accuracy of INA bearings

　　 A factory trial-produced exquisite instruments. The main shaft uses a 6202/P2 INA bearing and its accuracy still cannot meet the requirements. Then thicken the journal and make a roll on it. Instead of the inner ring, the steel balls are accurately measured. The size of each group is three grains, and each group of steel balls comes at an interval of close to 120°. Because of the addition of a processing surface and a mating surface, At the same time, the rigidity of the shaft and the INA bearing system is improved, and the close and equidistant spread of the largest three steel balls and the smallest three steel balls also improves the rotation accuracy of the shaft, thus meeting the accuracy requirements of the instrument.

　　2. Accuracy improvement method

After the 　　INA bearing is installed in the host, such as measuring the radial runout of the spindle, it can be found that the measured value of each revolution has a certain change ; When measuring continuously, it can be found that after a certain number of revolutions, this change will appear approximately repeatedly. The index to measure the degree of this change is the cyclic rotation accuracy. The number of revolutions required for the approximate repetition of the change represents the 'quasi-period' of the cyclic rotation accuracy. The magnitude of the change in the quasi-period is large, which is the poor cyclic rotation accuracy. .

　　 If the spindle is properly preloaded, the speed is gradually reduced to close to the required speed to implement the 'run-in' effect of the INA bearing, which can improve the cycle rotation accuracy of the spindle.