Implementation of equipment for induction heat treatment

1 Preface

Induction heat treatment has the advantages of high heating speed, energy saving, non-oxidative decarburization, no environmental pollution, and high production efficiency. These advantages are widely recognized by heat treatment workers, so it has developed rapidly in the past ten years. Of course, this is the actual demand, but it also significantly contributes to the development of domestic induction heat treatment equipment and technology improvement. For example, at "China FAW" Changchun company, there are more than 100 induction heat treatment installations, of which nearly 10 years - new or updated equipment - 50, almost all SCR and IGBT audio equipment. Now the heat treatment parts of "FAW" medium size to achieve a weight of 291.3 kg, accounting for 52% of all heat treatment parts, induction heat treatment has really strengthened half of the heat treatment.

2 China's early induction heat treatment equipment situation

In the early 1950s, with the construction of "FAW" and "drag-and-drag", a large number of high and medium frequency processing equipment was introduced from the Soviet Union, totaling about 20, as well as a very small number of Czech equipment. People learned from induction heat treatment. In the late 1950s, several domestic factories developed high and medium power power equipment, such as Tianjin Broadcasting Equipment Factory and Beijing Broadcasting Equipment Factory, to develop high-frequency tube equipment, Xiangtan Motor Factory and Jinzhou Motor Factory developed mechanical medium-frequency generator; Around the mid-1960s, Tianjin Labor Bureau Technical School (later Tianjin Ninth Machine Tool Plant) began production of a simple quenching machine [1]. They opened their own research and development and production precedent of induction heat treatment equipment.

3 Current situation and development of induction heat treatment equipment in China

Medium and high-frequency power supply equipment is the key equipment for induction heat treatment. At present, China's heat treatment industry, in addition to the highest spark gap power supply is not used, other several power supplies are used, which generate machine generators and high-voltage tube-type power supplies, despite lagging behind in some areas or factories, it is still the main production equipment. Now about the advantages and disadvantages of various power supplies, presented as follows:

3.1 Mechanical frequency generator

Mechanical medium-frequency generators, developed around 1920, when the United States, Ohio, Clark first used it for crankshaft quenching, which is the first for industrial production of intermediate power supply. Its biggest advantage is durability, in addition to running for several years to replace the bearing, almost no maintenance. Its disadvantages are often fixed, limited use volume, large area, noise, water consumption, power utilization efficiency is low, about 70 ~ 75% [2].

2.2 High-frequency power supply

High-frequency tube power was born around 1930. Its main advantage is simple adjustment, easy to use, despite the high frequency (after the development of super audio), the application volume is still wide (regardless of heating efficiency). Its main disadvantage is low power efficiency, about 50%, working voltage is too high, low safety, low power [2].

2.3 Thyristor (SCR) medium-frequency power supply

Thyristor (SCR) IF power supply, also known as SCR power supply, this power has been about 70 years in international development and has become widely used. China in the successful development of the 1980s and began litigation. In the early 1990s, quite mature, some technical indicators have reached the international advanced level. Induction hardening with thyristor frequency frequency is usually 2.5 ~ 8 kHz. It has many advantages compared with machine frequency: small size, light weight, no mechanical movement, low noise, easy start and stop, frequency can be adjusted according to the parts and in the process of automatic tracking, to maintain the highest power factor for starting Easy installation, no need for special base, independent quenching equipment up to 1000 kW, electrical efficiency up to 90% [2].