What is the induction heat treatment process? How does it work?

1.The meaning of induction heat treatment process

Induction heat treatment process refers to the phenomenon of conductor heating caused by alternating current in the conductor. This technique is based on Faraday’s discovery of electromagnetic induction.

In 1957, the United States developed the thyristor, which played a milestone role in the development of power electronic devices, but also triggered a great revolution in induction heating technology. In 1966, Truthful and West Germany first developed the induction heating device by using the thyristor, and since then, induction heating technology has entered a period of rapid development. With the rapid development of power electronic devices in the 1980s, the induction heating device also began to adopt the newly developed thyristor, and the technology became more and more advanced.

The real application of induction heat treatment technology in China was in 1956, mainly in the automobile industry, and the technology was mainly introduced to the Soviet Union. With the wide application of induction heat treatment technology, induction quenching technology has also been a great development. At present, the application of induction hardening technology has become increasingly extensive. At present, the induction heat treatment process is mainly used in automobile manufacturing and the metallurgical industry. It is fast, efficient, energy saving, clean, and easy to realize automatic and on-line production. It belongs to the contact heating mode. This method of heating not only works in a variety of carrier gases without causing any pollution but also increases the highly flexible selectivity of heating surfaces and depths.It is these technical characteristics of the induction heat treatment process that make this technology more and more widely recognized and supported.

2.the advantages of induction heat treatment process

In recent decades, induction heat treatment technology has been widely applied and innovated in metallurgy, machinery, automobile manufacturing, and other industries. The variety and number of induction heat treatment workpieces in the mechanical industry are also increasing year by year. These achievements and progress are closely related to the advantages of induction heat treatment technology. The author analyzes the following advantages from the characteristics of the induction heat treatment process:

(1) Induction heat treatment process is conducive to the implementation of the national principles and policies of environmental protection and energy conservation and sustainable development

The electric energy that has an electric tiger to say is the main power that the machine industry trades. According to statistics, the electricity consumption of heat treatment accounts for 25% of the total electricity consumption of the mechanical industry, and the electricity consumption of induction heat treatment accounts for about 20%-25% of the total electricity consumption of heat treatment equipment. Induction heating can automatically control the whole process of process implementation, avoiding unnecessary waste and consumption of power resources. The efficiency of the induction heat treatment process is also improved with the reduction of power resource consumption.

(2) The induction heat treatment process is conducive to speeding up the heating speed and improving the production efficiency

Since the whole process of heat treatment is completed by induction, the whole process of heat treatment can be shortened more than 4 times. It reduces the waste of power resources, accelerates the heating speed of the heat-sensing heat treatment process, promotes the overall production efficiency, and finally makes enterprises obtain high profits.

(3) Induction heat treatment process is conducive to the realization of production automation

In inductive heating and quenching machine tool equipment, closely cooperate with the microprocessor equipment such as machine, can realize the running of production next material quenching machine tool and workpiece full automation in the whole production line, using microcomputer processing technology to quench heating and cooling time, heating speed, quenching machine tool speed, the temperature of quenching medium, monitor electrical parameters such as frequency converter, hot and cold processing, automatic continuous production.

(4) The induction heat treatment process provides a healthy and good working environment for the staff

Induction heating treatment is not like an electric furnace, an oil furnace in the working state to release a lot of heat radiation, resulting in the pollution of the working environment. The induction heat treatment process only needs to be carried out at room temperature, and it is very convenient to open and shut down the furnace. Therefore, induction heat treatment technology for the frontline staff’s health to provide good working conditions.

(5) The induction heat treatment process is conducive to improving the surface strengthening effect

Induction heating can improve the phase transition temperature of metal materials and accelerate the austenite transformation. When heating with induction resistance and high-power pulse induction heating, finer martensite structure can be obtained, surface strength can be improved, and the consequences of deformation can be alleviated to some extent.

3. Practical application of induction heat treatment technology

(1) The application of induction heat treatment technology in practice

Application in the automobile manufacturing industry. Induction quenching technology has been widely used in automobile production. In addition, there are more than 200 kinds of parts in medium and heavy vehicles, light vehicles, and several kinds of cars that need induction hardening. At present, the automobile parts which adopt induction quenching mainly include automobile axle parts that transmit power torque and various pin axle parts. In addition, induction hardening technology has also been used in the manufacture of automotive leaf springs by Dongfeng Motor Company. At present, the research and development of low hardenability steel and limited hardenability steel by scientific and technical personnel is also applied to automobile steering worm, cross shaft, universal joint, and other parts.

Application in the tractor industry. With the improvement of economic level, the introduction and digestion and absorption of tractor products and technology at home and abroad are becoming more and more people to the tractor enterprise technology and manufacturing technology is also put forward higher requirements, so the induction heat treatment process in the industry has been rapid development, a large number of induction heat treatment process and solid-state induction heating power supply, NC quenching machine tool and other advanced equipment in the development of agricultural machinery enterprises are great, the use of the induction heat treatment process to improve the overall technical level of the agricultural machinery industry in China.

Applications in the construction and oil industry. In the construction industry, various induction heat treatment processes, such as induction heat treatment production line for high-strength prestressed reinforcement, stabilization production line for low-relaxation prestressed steel wire, and induction heat treatment production line for petroleum casing, have been well utilized by virtue of its advantages such as small quenching deformation, high production efficiency, and good working environment. The use of this technology allows the construction industry to speed up progress, and the quality of the project is guaranteed. And the working efficiency of the oil industry has been greatly improved, promoting the rapid development of the industry used.

(2) The deficiency of induction heat treatment technology in practice

There is no perfect thing in the world, everything is in the constant self-denial and affirmation of innovation and development. Under the test of the induction heat treatment process in practice, compared with the carburizing and quenching technology, the following points and views on the defects of the induction heat treatment process are summarized.

With the early 1980s computer in the field of carburizing control widely used, and carburizing technology in the theory of constant supplement and innovation, carburizing quality has been a strong guarantee, carburizing process and operation level has also been greatly improved and improved. The carburizing medium of the technology is very expensive, the energy consumption is big, the workpiece distortion is big, the pollution to the environment is serious and so on the problem and the insufficiency did not shake its dominant position in the heat treatment strengthening technology. Compared with the induction heat treatment process, there is still a certain gap.

Firstly, the automatic control function of induction heat treatment equipment is weak, which cannot meet the professional requirements. Secondly, professional guiding standard documents for induction heat treatment process are too few, and lack of timely addition and revision; Finally, there is a lack of in-depth research on the theoretical knowledge of induction heating treatment process, a lack of abundant theoretical monographs and papers with relevant professional knowledge, and even if there are related literature, most of them stay on the surface research of literature, lacking process operability. Without the guidance of scientific theory, there are few leapfrog development and progress in practice.

The above mentioned is from the professional perspective of induction heat treatment. In addition to the lack of professional, induction heat treatment processes related to the staff of the awareness of learning and innovation is also lack.It is because of not good at learning, not good at innovation, will make the induction heat treatment industry progress is very slow. Secondly, most small and medium-sized enterprises lack specialized new equipment, new processes and new technologies, which are all hardware facilities. Hardware facilities are the foundation. Without these hardware facilities, it is just like the saying “one cannot make bricks without straw”. Technological improvement and innovation cannot be carried out.

4. Development approaches and measures for the inductive heat treatment process

(1) To strengthen induction processing technology practitioners of learning awareness and innovation awareness

Let them strengthen the learning of theoretical knowledge of induction heating treatment. Only by mastering the theoretical knowledge and principle of induction heat treatment process can they carry out high-level innovation and improve the level of induction heat treatment process. Let each employee improve their comprehensive quality through continuous learning so that each employee can realize the innovation of induction heat treatment technology.

(2). The government should play its regulating and encouraging role

Develop the corresponding technology innovation reward system to create a good innovation environment for employees. Part of the funds will be provided to purchase advanced test equipment and updated and improved theoretical knowledge books to provide a hardware basis for employees’ learning and innovation. Then invite professionals from all over the country to train employees in various aspects of knowledge and skills to improve their comprehensive quality. In addition, the government should properly play its supervisory role to supervise the problems in the application of induction heat treatment technology, as well as the illegal behaviors such as cutting corners in the operation of employees.

(3) Expand the application scope of the induction heat treatment process

The induction heat treatment process is mainly used in the automobile manufacturing industry and metallurgical industry. The technology is now being applied to tractors, bearings, construction, and the oil industry. Among them, induction quenching technology for the small inner hole, variable power of shaft parts, and induction quenching technology for variable moving speed of parts must be used more in the application of induction heat treatment technology in the tractor industry. Find different induction heating technologies in different industries. The induction heat treatment process will be extended to the plastic, rubber industry, to the electronic industry. In addition, the use of induction heating technology for bonding, as well as the role of sealing and packaging. Expand the application range of induction heating technology, play its powerful role and advantages.

(4) To broaden the source of induction power supply and constantly introduce the world’s advanced induction power supply

Paving the way for induction heating technology. At present, induction power on the market from the United States, Britain, Japan, Germany, Spain, and other industrial developed countries SIT, IGBT, MOSFET national solid-state transistor power. The induction power supply with complete specifications, small size, and high efficiency of electric energy conversion is constantly introduced. Induction quenching machine tools, which are developing towards flexibility, automation, and intelligent control, should be introduced to diagnose, alarm, and display process parameters and problems of induction quenching device in the process of application.

(5) Strengthen the role of heat treatment cooperation center, vigorously develop the induction heat treatment process

Although induction heat treatment technology has many advantages, it has high investment cost and difficulties in heat insulation and temperature measurement, especially at present some non-professional heat treatment plants are not strong enough to buy new equipment and introduce new technology. Therefore, the heat treatment cooperation center must play its due role to help small and medium-sized heat treatment enterprises to solve various problems, take the lead to expand the use of induction heat treatment.

5.Development prospect of induction heat treatment technology

At present, the application of the induction heat treatment process is still very limited, and it is mostly used in the automobile manufacturing industry, metallurgical industry, construction industry, and petroleum industry. In addition, the application of induction heat treatment technology in gear quenching is mainly limited to small and medium-sized model gears with little transmission power. For large gear has appeared a lot of quality problems.

Although the developed carburizing quenching technology has been able to be used in practice, with the rapid development of cement, wind power, and metallurgical industry, the induction heat treatment process needs more and more gearbox power. After carburizing and quenching, the gear deformation is very large, the actual carburizing hardened layer depth of the gear surface after grinding the finished product is not uniform. Therefore, in the effective control of the induction quenching temperature and hardened layer depth uniform and controllable problems need to continue to research and innovation, and further improve and improve the technical level of the process, change the status quo. The application of induction heat treatment technology can be extended to a wider range of fields only through continuous technical innovation and overcoming various difficulties.

If the process of induction heat treatment can be continuously modified and improved under the test of practice and the continuous learning and innovation of heat treatment staff, it will be a technology with great development potential. As a philosophical saying goes, “The future is bright, but the road is tortuous.”There is still a long way to go in the development of induction heat treatment technology, but as long as we take every step in a down-to-earth way, induction heat treatment technology will eventually move to a wider industry and help China to embark on the road of sustainable development with high production efficiency, low consumption, and no pollution.

6.The concluding

In recent decades, induction heat treatment technology has been widely applied and innovated in metallurgy, machinery, automobile manufacturing, and other industries. But the practice has proved, in its popularization and the development process also has many difficult problems. In order to give full play to its advantages and advantages, it is necessary to strengthen the propaganda of technology and promote the new equipment, new process, and new technology of induction heat treatment. Revise and perfect the standard of induction heat treatment, and incorporate the written rules and standards into the mechanical design manual. With the increasing proportion of the induction heat treatment process in the production, the production efficiency is improved, the energy consumption is reduced to the minimum, and the road of sustainable development will be further improved.

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