Research On An Induction Heating Bearing Inner Race Replacer With Adjustable Bore

Bearings are important components of modern machines. The combination between bearing and shaft is often fit, which makes it difficult to remove bearing from shaft or install bearing on shaft. The traditional methods of disassembling bearing can be divided into mechanical methods and heating methods. The mechanical methods include using top-pulling machine or chest developer to pull down bearing from shaft, etc. These mechanical methods often damage the inner surface of the bearing and reduce the life of bearing. The heating methods generally include heating bearing by roasting or oil cooking, etc, which typically only be used for interference fit of bearing. It is difficult to control the heating temperature for the heating methods, which not only easy to make the surface of bearing be oxidied, but also pollte the environment.Because of these traditional approaches have so many shortcomings, they are been replaced by electric heating methods gradually. Induction heating is one typical form of electric heating methods. The principle of induction heating is coil provided alternating current generates alternating magnetic field, which produces eddy current in the metal. So the metal is be heated by the eddy heat. This electric heating method has the advantages of easying to control temperature, no pollution, high efficiency, etc. So it has been widely applied to many fields of the industrial production. It will give full play to the advantages of the induction heating technology, if it is used for disassembling bearing.The purpose of this study is to design a bearing induction heating replacer with variable bore. The replacer based on a principle of induction heating can change its bore to assemble or disassemble bearing inner races with different outer diameters rapidly and have no damage to bearings. This paper has done some research as follows:1. Initially, this paper had done some theoretical research about induction heating, including skin effect and its influence factors, magnetic field intensity distribution and power consumption in the metal during induction heating, temperature distribution in the metal when heated in alternating magnetic field and so on. The theoretical research set the stage for the further design of the bearing replacer.2. On the basis of the theory, the paper indentified the trend of the magnetic field lines in the bearing inner race during induction heating, and designed the replacer model. The model includes the main structure, the support and the drive mechanism. Adjustable bore is the most prominent feature of the replacer. The radial magnetic conductor of the replacer can move along the radial of the replacer, which make the replacer clamp bearing inner races with different diameters. This structural characteristic greatly expands the application scope of the replacer. The support and drive machanism are used to reduce the trouble of moving the replacer when working, which increases automation of the replacer.3. To verify whether the replacer meets the request of disassembling or assembling bearing inner race rapidly and with no damage, its work process has been simulated using finite element analysis method. Simulation contents include:the distribution of the magnetic field in bearing inner race and shaft, the temperature changes over time in the bearing inner race and shaft, the distribution of the temperature along the radius of the bearing inner race and shaft, the distribution of the expansion size in the bearing inner race and shaft. The simulation results shown the existence of skin effect, and gave the distributions of temperature and expansion size in the bearing inner race and shaft. Factors influencing the distribution of temperature and expansion size had been discussed. Ultimately, some reasonable structure parameters of the replacer had been determined. The parameters mainly include turns of coil, wire size and magnet size and so on, which provide reliable theoretical basis for the further production of the replacer.4. Based on the structural parameters obtained by simulation, this paper produced a prototype of the replacer, and its performance was investigated experimentally. Experiment contents include:the temperature measurement of different isothermal in the bearing inner race, the expansion size measurement of the inner radius of the bearing inner race, the power consumption measurement when the replacer working. Experimental results shown that the replacer can meet the requiremengts of disassembling or assembling bearing inner race rapdily and with no damage. The design of the replacer provides a new and efficient method for removing or installing bearing.