Induction heating, as a new subject, has come to real application in the past 30 years.In today’s energy shortage, its importance is particularly prominent, technology is rapidly improving, increasingly widely used. Induction heating technology began to be developed in China after the reform and opening up, and its application prospect is very promising.
1. Induction heating characteristics
(1) High heating temperature and non-contact heating.
(2) High heating efficiency.
(3) Fast heating speed.
(4) The temperature is easy to control.
(5) Local heating can be used.
(6) Easy to realize automatic control.
(7) Good working environment, almost no noise, and dust.
(8) Less workspace and high production efficiency.
(9) Can heat workpiece with complex shape.
(10) The workpiece is easy to heat evenly, and the product quality is good.
(11) The solution in melting has the effect of electromagnetic stirring. The liquid metal components can be evenly adjusted, the solution temperature is uniform, there will be no local high temperature. Less burning of metals is more important for the smelting of minor metals.
2. Advantages of induction heating
The first is low energy consumption. The actual billet heating efficiency of induction melting furnace and induction diathermy furnace can reach 65% ~ 75%, while that of the flame furnace and various chamber furnaces is only about 30%.
Second, this type of furnace does not need a coal furnace, gas furnace, resistance furnace, and another necessary preheating process, easy to use, simple to operate, can work for a long time continuous or according to the need to open or stop at any time, manual can also be fully automatic or semi-automatic work, can have an absolute advantage in production scheduling.
Third, without heat for artifacts as a whole, can choose local heating, and less power consumption, small deformation and heating speed, can make the workpiece in a very short period of time to achieve the required temperature, so that the workpiece surface oxidation and decarburization of very low heating defect degree, can be used for steel material such as steel, iron, tungsten, molybdenum can also be applied to chemical activity strong heating of aluminum, titanium, zirconium, niobium or heat treatment.
Fourth, induction heating equipment can be installed on the production line, easy to realize the automation and mechanization of the production line, easy to manage, can effectively reduce transportation, save labor, improve production efficiency.
Fifthly, induction heating also has the advantages of high power utilization rate, environmental protection, and energy saving, safety and reliability, and a good working environment.
Based on the above advantages, in the electricity instead of coal, oil, gas and other non-renewable energy gradually become the dominant energy in the heating field today, induction heating melting, heating, and other fields have been increasingly widely used, electric heating, especially the application of induction heating has a very broad application prospect, induction heating equipment manufacturers have a broad space for development.
3. Application in automobile manufacturing
The vigorous development of the automobile industry has brought unprecedented development opportunities to the auto parts industry. Induction heating technology is also being used more and more widely in the field of automobile manufacturing.
In smelting, casting is an easy – to – form metal processing method. Parts of various sizes and complex shapes on automobiles can be made by casting method.It can be said that in the development of the automobile industry to make the best use of almost all casting processes in the automobile industry can do their best. The main smelting processes used in the production of casting automobile parts at home and abroad are cupola smelting process, medium-frequency induction furnace smelting process, and cupola – medium-frequency induction furnace double melting process. Induction smelting furnace is also being increasingly widely used in the casting industry due to its technical advantages.
In terms of heating, according to statistics, the induction heat treatment parts of the former Soviet Union in the automobile industry has accounted for 40% ~ 45% of the heat treatment parts. Induction heating technology developed to today, its application and development degree is self-evident.
Induction heating technology is mainly applied in the following fields in the automotive industry:
(1) Metal smelting.
(2) Heating of forging blank.
(3) Heat treatment of auto parts.
(4) Induction heating curing of auto parts after adhesion.
(5) Induction heating semi-solid forming.
(6) Induction heating assembly.
(7) Induction heating brazing.
4. Current situation of induction heating abroad
With the development of power semiconductor devices and the continuous development of power electronics technology, the appearance of induction heating devices is changing with each passing day, especially in terms of the volume, quality, and performance of the devices. Such as frequency, frequency conversion device with the capacity of the transistor type and tube type variable frequency device smaller than two-thirds, a two-thirds reduction in weight, water-saving, 1/2, save third power consumption, efficiency increased by 35%, service life is longer, more safe and reliable, easy to realize automatic control, to improve the heating efficiency and quality, less maintenance workload, can do along with it.
The technology development and application of induction heating devices in Germany, The United States, The United Kingdom, France, Japan, Italy, Spain, Belgium, and Russia are at the forefront of the world.
5. Domestic development and current situation
The application of induction heating technology in China began in the 1950s and was mainly developed after the reform and opening up, mainly used in machine tools, automobiles, tractors, and other manufacturing industries. Induction heating focuses on the surface quenching of the workpiece, but less is used in melting and diathermy. Induction heating technology comes almost entirely from the former Soviet Union and the Czech Republic. In the 1980s, Zhejiang University independently developed the first parallel thyristor intermediate frequency power supply and promoted it to the whole country.
In the 1990s, some foreign induction furnace companies came to China directly to set up factories, such as American Yingda Induction heating Company and Biller Company, etc., competing with domestic manufacturers in the same industry. Their products have high technical content, large power supply, full brand, large furnace tonnage, and large production line scale, occupying a large part of the domestic market. Only their equipment price is high (domestic products with the same performance is about 1/5 of its price), which makes domestic manufacturers have a certain market development space.
