| Gears and racks,as one of the most common transmission mechanisms in modern equipment,have the characteristics of high transmission efficiency,compact structure,long life,reliable work,etc..For those reasons,they are widely used in the lifting systems of large-scale machinery and equipment such as mines and water conservancy.Short service life,low reliability and complicated structure have already become the three major problems that hinder the development of Chinese gear industry.As one kind of surface hardening techniques,induction hardening is a surface hardening technique that uses internal heat source for heating.It features of fast heating speed,high thermal efficiency,and uniform hardening layer distribution.It can effectively reduce the phenomenon of oxidation and decarburization on the surface of the workpiece.The depth of the hardened layer is easier to control,and the energy consumption is lower.In the process of the development of the gears and racks from the soft tooth flank to the hard tooth flank,the induction hardening technique has played an important role.For large modulus and heavy duty racks,limited by their own structural size and strict load environment,higher requirements are put forward on the induction hardening technique.Based on the above,on the basis of the study of the principle of electromagnetic induction heating,the following research has been done for the induction heating technique of large modulus and heavy duty racks:In order to improve the failure problem of large modulus and heavy duty racks after induction heating in the prior art,this paper proposes a scanning heating method along the tooth profile,and designs an inductor structure suitable for this processing method.Based on ANSYS software,a static numerical simulation of the rack induction heating process is carried out.This paper analyzed the internal law of the temperature distribution after the rack is heated.The analysis includes three aspects which are the influence of the coil size on the temperature distribution in the face width,the characteristics of the magnetic field distribution during the induction heating process,and the temperature distribution in the heating depth.In order to improve the reliability and accuracy of the simulation analysis of the rack induction heating process,this paper proposes a "Load migration for loop computation" method that takes the relative motion of the inductor and the rack into consideration,and it establishes the coupling model among electric field,magnetic field,and motion field which realizes the dynamic simulation analysis of the heating process of the rack along the tooth profile scanning.On this basis,the influence of the coil feed speed on the temperature distribution after the rack is heated has been studied.It also makes an analysis of the temperature uniformity along the tooth profile after the rack is heated.aiming at the shortcomings of the transverse flux induction heating method,this paper also proposes a method of arranging magnetizer in sections to improve the temperature distribution along the tooth width after the rack is heated.For the method of scanning heating along the tooth profile proposed in this paper,related experiments were carried out by building a rack induction heating experiment platform.Under the same conditions,the "Load migration for loop computation" method was used for numerical simulation.The comparison and analysis of the temperature change data of the experimental group and the simulation group at the same position verifies the accuracy of the numerical simulation results.At the same time,it also proves that the analysis of using the "Load migration for loop computation" for simulating the heating process of the large modulus and heavy duty racks along the tooth profile scanning is reliable. |
