Although the carburizing and quenching process has unparalleled advantages in obtaining the uniform distribution of the hardened layer and the stability and reliability of the quenching quality, in the actual production process, there are long production cycles, large heat treatment deformation, and difficulty in machine loading. Poor cleaning, energy consumption and other shortcomings. These defects in the carburizing and quenching process are the advantages of induction heating and quenching technology. Therefore, how to properly use the induction heating quenching technology is an urgent problem to be solved.

China's Erzhong Group Gear Factory Liu Jiquan

With the intervention of computer technology in the carburizing process, the carbon atmosphere in the carburizing quenching furnace is precisely controlled, so that the uniformity of the hardened layer after carburizing and quenching, the depth of the hardened layer, the stability and reliability of the quenching quality are ensured. In addition, domestically, especially in the heavy-duty manufacturing industry, the introduction of CNC forming gear grinding machines, the surface strengthening method of gears is increasingly inclined to adopt the heat treatment method of carburizing and quenching. However, the commonly used induction heat treatment method is unstable due to the quenching strengthening effect, and the quenching cracking tendency is large. It is difficult to obtain the hardened layer distributed along the tooth profile, and the root reinforcement effect is poor; the frequency and power adjustment of the intermediate frequency heating power supply is poor, and it is difficult to achieve Real-time adjustment of induction heating quenching parameters. Therefore, in recent years, applications on gears have become less and less.

To this end, the China Gear Professional Association Gear Heat Treatment Working Committee held a special seminar on gear induction heating and quenching technology in Taiyuan in September this year. The author was fortunate to participate in the event. The participants summarized the application results and successful experience of induction heating quenching technology on gear surface strengthening in recent years, which made us see the application prospect of induction heating quenching in gear strengthening. As a technician who has been engaged in induction heat treatment in professional gear manufacturing factories for many years, I have talked about some of the experience of induction heating and quenching technology in gear strengthening technology.

Although the carburizing and quenching process has unparalleled advantages in obtaining the uniform distribution of the hardened layer and the stability and reliability of the quenching quality, in the actual production process, there are long production cycles, large heat treatment deformation, and difficulty in machine loading. Poor cleaning, energy consumption and other shortcomings. Take the main reducer on the main drive of the rolling line equipment produced by our group company, the gears and gear shaft products with large modulus ( m >25 or more) in the gear base, due to the presence of non-carburizing surface The protection problem, although the non-carburizing part is protected by anti-seepage coating in the carburizing process, the effect is not significant, which makes the semi-finished car before the gear and gear shaft grinding, the finishing process is difficult, and the tool consumption is increased. As a result, we have to add a process to the carburized layer of the non-permeable part after carburizing, which invisibly increases the production cycle. The main reason is that the heat treatment deformation is large, and the hardened layer distribution of the tooth surface is uneven in the actual processing, the tooth size is out of tolerance, the precision after grinding is reduced, and the normal use requirement is affected. If measures are taken to increase the amount of retention, the depth of the carburized layer will be increased first, which will prolong the carburizing cycle and cause the brittleness of the carburized layer to increase, which will affect the quality of the product. These defects in the carburizing and quenching process are the advantages of induction heating and quenching technology. Therefore, how to properly use the induction heating quenching technology is an urgent problem to be solved. According to the practice of induction heat treatment for many years, the author believes that the induction heating along the tooth groove quenching process can completely solve the above problems under the normal use of the gear parts, provided that the following problems exist in the process of quenching along the groove problem:

(1) Design and manufacture of quenching sensors along the tooth gap.

(2) The protection of the hardened tooth surface is how to prevent the tooth surface from "tempering".

(3) Reasonable choice of quenching cooling method.

For this reason, in the inner ring gear reinforcement mode of the drum-shaped toothed shaft product in the main transmission of the 8750 rolling mill of Guosteel, Guofeng 1450 rolling mill and 1750 rolling mill of Handan Iron and Steel Co., Ltd., I used the branch along the tooth groove. The quenching process replaced the original carburizing and quenching process and achieved remarkable results.

It is worth noting that the heat treatment in the 21st century is developing in the direction of high efficiency, energy saving, precision and cleanliness, and advocates “less pollution, less distortion, less (quality) dispersion, less waste, less oxidation, less decarbonization, The concept of “no labor, no waste”. China's "Ten, 15th" plan also clearly puts forward an environmentally friendly and energy-saving economic development policy. All of these indicate that as a clean and energy-saving heat treatment process, as long as the potential weakness is solved, the application of induction heating and quenching technology on the gear has a certain vitality. With the maturity of the application of full-frequency solid-state IGBT inverter power supply technology, the adjustment of the frequency and power of the heating power supply has been completely solved, and the adjustment and control of the induction heating quenching parameters are fully guaranteed, and the application of numerically controlled quenching machine tools is widely applied. The quenching quality of the induction heating quenching, the stability and reliability of the strengthening effect will be further ensured. Since the frequency of the power supply is adjustable in the range of 50-100 Hz, the depth range of the hardened layer can fully meet the requirements of the gear parts, and the depth of the quenching layer can reach more than 10 mm, which is impossible to achieve by the current carburizing and quenching process. In the future, heavy-duty gears such as rolling, shipbuilding, lifting and mining will inevitably develop to a deeper level, while deep carburizing (>5mm) is not mature in China at present.

(1) Steels suitable for deep carburizing have to be studied;

(2) The carburizing cycle is long, and the problem of quenching deformation needs to be solved urgently;

(3) How to ensure the quality of the seepage layer, and the induction heating quenching technology undoubtedly has an absolute advantage in this respect.

The author believes that the majority of workers engaged in induction heat treatment, as long as they work hard, conduct extensive and in-depth research on the weaknesses in gear strengthening, and find solutions. I believe that the future application of induction heating and quenching technology will be even more on gears. good prospect forecast.

This article was issued by the "Mechanical Workers" (Hot Processing), the 11th issue of 2006, so stay tuned!
Copyright, without written permission , may not be reproduced!

Bathroom Showers

shower set,thermostatic showers,bathroom shower accessories,concealed shower,exposed shower

Guangdong Kinen Sanitary Ware Industrial Co.,Ltd. , https://www.kinengroup.com