Four stages of development of induction heat treatment technology in China

The development of induction heat treatment technology in my country can be divided into four stages, namely the comprehensive introduction of former Soviet technology stage and the self-reliance stage before the reform and opening up, the rapid development stage and the independent innovation stage after the reform and opening up.

(1) The stage of comprehensive introduction of former Soviet Union technology. In the early days of the founding of New China, my country's induction heat treatment technology received comprehensive assistance from the former Soviet Union in three aspects: process equipment design and manufacturing, factory design, and technology and theory.

(2) Self-reliance stage. After 1960, the development of induction heat treatment technology in my country entered the stage of self-reliance. The sign is that the design, equipment and technology of the induction heating section in the construction of the new automobile plant are almost all self-sufficient. The induction hardening machine tools and sensors of the machine tool factory and heat treatment plant are also all self-sufficient, showing a prosperous scene in which a hundred flowers bloom. Automotive induction heat treated parts account for an increasing percentage of all heat treated parts. The research and development of some new processes such as induction quenching of rail ends and quenching of low-hardenability steel gears have been carried out, and academic exchanges on induction heating have emerged.

(3) Rapid development stage. After the reform and opening up, through inspections, studies, participation in conferences and exchanges in industrially developed countries, some advanced induction heating processes, equipment, technical books and standards were introduced, which caused great changes in my country's induction heating processes and equipment. Representative examples include longitudinal current heating of stepped shafts (applied to primary quenching of half shafts), rotational heating of crankshaft necks (applied to engine crankshafts), gear imitation tooth profile quenching, and use of hardness method to measure the depth of the hardened layer (replacing the original metallographic method). ), can process magnetic conductors and oxygen-free copper materials for inductor manufacturing, etc. Great changes have also taken place in the development of induction heating enterprises. Induction heating power supply factories, inductor factories, transformer factories, and quenching machine tool factories have been established one after another. The supply of complete sets of equipment has begun, and has begun to move towards a more advanced level.

(4) Independent innovation stage. At present, my country's induction heat treatment technology is in the stage of independent innovation.

1) The induction heating equipment manufacturing industry is developing rapidly. In terms of power supply, IGBT ultrasonic induction heating equipment and portable power supplies are basically self-sufficient and have exports. In terms of quenching machine tools, equipment that is difficult to manufacture, such as fully automatic crankshaft quenching complete sets, horizontal large-scale marine crankshaft quenching machine tools, soft-belt raceway quenching devices and CVJ CNC quenching machine tools, have been able to independently design and produce. In terms of sensors, the number of professional sensor manufacturers is constantly increasing, which is conducive to improving the technology and quality of such products.

2) The application of new induction hardening processes continues to expand. For example: longitudinal induction hardening of shafts has expanded its application scope in the automobile and tractor industries. Advanced processes such as soft belt-free quenching of slewing bearing raceways, quenching of three-column slide sets, and dual-frequency induction quenching of gears have been used by Chinese companies and are being continuously improved.

3) The application scope of induction heat treatment continues to expand. Induction hardened parts are no longer limited to improving wear resistance, but have developed to improve the fatigue strength, torsional strength and bending strength of the workpiece. Induction annealing of steel pipe welds improves the durability of steel pipes. The application fields of heat treatment have expanded from machine tools, automobiles, tractors, engineering machinery, and locomotive manufacturing to petroleum machinery, metallurgical manufacturing, aerospace and other fields.

4) Computer simulated induction heat treatment has been carried out in some factories and research institutes. This new technology of virtual trial production will replace the tedious and time-consuming on-site process adjustment, which can be called a process debugging revolution.

5) Induction hardening itself is an energy-saving process, but due to poor equipment, poor technology and no reasonable assessment of unit power consumption (that is, the overall quality of the part is used as the assessment unit rather than the thickness of the hardened layer), the induction hardening process is There are unreasonable energy consumption loopholes. GB/T 10201-2008 "Guidelines for the Rational Use of Electricity in Heat Treatment" has formulated a new power consumption quota for induction hardening. It is calculated based on the depth of the heating layer and the heating surface area. It is completely different from the overall quality of the workpiece as the calculation basis. This guideline The implementation of the regulations will promote the development of induction heat treatment equipment.

6) Formulated or revised a series of relevant national standards and machinery industry standards for induction heat treatment processes, equipment and energy conservation. The formulation and implementation of these standards will play an important role in induction heat treatment technology, workpiece quality, and equipment quality.