The heat treatment process of inner ring gear quenching by medium frequency induction heating machine

The internal ring gear is an important part of the reducer of automobiles and tractors. Its working conditions are quite harsh. In order to meet its working performance requirements, many manufacturers use medium frequency induction heating machines for quenching heat treatment. Today, we will focus on the medium-frequency induction quenching process of the inner ring gear.

The material used for the 80-type internal ring gear is selected 45#. The technical requirements are that the normalized hardness of the blank before heat treatment is 179~238HB. Before heat treatment, the inner diameter is measured with a measuring rod of 7mm diameter to be 232.50~232.60mm. After heat treatment, the M value = 231.85 -232.20mm, the required hardening layer depth is 1-4mm, and the hardness is 52~57HRC. For this reason, we use a medium frequency induction heating machine for quenching heat treatment to meet its technical requirements.

(1) Quenching sensor and fixture

The inductor for quenching the inner ring gear is an inner hole type quenching inductor. Taking into account the particularity of the quenching structure of the internal gear, in order to ensure that the deformation of the parts after quenching is regular and the deformation is small, the lower end surface and the outer circle can be used to position the induction quenching of the inner gear at the same time. There are 4 clamps designed in the outer circle. Spring, each circlip is equipped with screws and springs, and the 4 circlips have uniform elasticity. This automatic telescopic flexible fixture can keep the workpiece in a flexible positioning state during quenching, effectively control changes in its M value, and eliminate taper and elliptical deformations. In order to prevent the lower tip from loosening when the clamp is used for a long time, a thin copper sleeve is used to cover it, so that the lower tip and the socket fit closely, and the workpiece rotates flatter after adjustment.

(2) Adjustment of process parameters

The process test is to use a 160KW, 8000Hz medium frequency induction heating machine and a hydraulically driven vertical CNC quenching machine to perform medium frequency induction quenching of the internal teeth of the 80-type internal ring gear. We conduct this on a 160KW medium frequency induction heating machine. By adjusting the transition zones at both ends of the internal teeth to make them relatively the same size, we change the heating time, delay time and water spray time according to the principle of thermal expansion and contraction, so that the workpiece can increase the amount of shrinkage. Through extensive experiments, the best process parameters as shown in the table were finally optimized:

Medium frequency induction heating process parameters of inner ring gear

As an important part of automobiles and tractors, the ring gear's heat treatment quality seriously affects the overall operation of the machinery. As a professional manufacturer of medium frequency induction heating machines, Zhengzhou Gou's fifteen years of experience has enabled us to have a good understanding of the heat treatment of various workpieces. If you want to know more about the heat treatment of automobile parts, please call us for consultation.