China's gear products have made great progress in the past 10 years. Many products have reached or approached the international advanced level, but there are still quite a large number of gears and gearbox products. The gap between vibration noise and fatigue life is significantly different from the international advanced level. This is closely related to gear materials and heat treatment equipment and process level. They have become the bottleneck for Chinese gear products to catch up with international standards.
Based on this clear understanding, the Gear Professional Association not only established a committee for materials and heat treatment, but also held a seminar on heat treatment every year. Recently, they organized the “2007 Carburizing and Quenching Seminar†in Changchun. More than 100 industry experts and representatives of gear manufacturers, heat treatment equipment and accessories manufacturers gathered together to discuss how to further improve the quality of gears. Suggestions and suggestions.
Wang Shengtang, Secretary General of the Gear Professional Association, summarized the outstanding achievements of China's gear products in recent years. He believes that this is also the result of materials and heat treatment.
China's gear industry has developed rapidly in recent years, the total value of gear production has reached 70 billion yuan, and all kinds of gear products have been fully developed.
First of all, the self-owned manual transmission products reach or are close to the international level. Among them, the medium and heavy-duty automobile gearbox represented by Shaanxi Fast is particularly outstanding, and the products of Minjiang and Datong also have good performance. Mainly able to match various models from 5 tons to 50 tons, and exported to more than 10 countries in Europe and America; the manual transmission of the slight car represented by Changchun Automobile Gear Factory and Chongqing Qingshan has also made rapid progress; represented by Zhejiang Shuanghuan The professional manufacturers of motorcycles and automobile gears have been supplied to Japanese and European companies; key component companies represented by Tianjin Tianhai Synchronizer have also participated in international support.
Secondly, Shaanxi Hande Axle Factory has realized the first technology export in China's axle manufacturing enterprises. This shows that on the basis of the introduction of technology, combined with China's national conditions, through continuous improvement and secondary development, it is possible to form autonomous products. Series, including strong, quenched, hardened, widened track, 13t ~ 16t series.
There are also medium and small power industrial universal gearboxes that are being exported to Europe and the United States in batches. In recent years, the international big names of medium and small power industrial universal gearbox represented by German SEW have poured into the domestic market. In the competition with them, a group of Zhejiang private enterprises such as Stellar, Wanjie, Dongli and KONE have performed. Outstanding, the product quality level has improved rapidly, and the products have been exported to Europe and the United States in batches.
In addition, industrial high-speed and heavy-duty transmission products are already available for multinational companies. In the past five years, after years of process tempering and large-scale technical transformation, a group of enterprises in China have formed world-class high-speed and heavy-duty gear manufacturing capabilities. High-speed heavy-duty gears for cement, metallurgy, mining, marine, gas turbines, etc., have been involved in international support, including many world-renowned companies such as Demark, SMS, and US PH. Heavy tooth, Nigao tooth and Hang forward have reached or approached the level of international advanced companies in the quality of 3~4 hard tooth surface hardened gear box.
Wang Shengtang said that the level of gear products is inseparable from the support of China's heat treatment process equipment. The most outstanding performance is that the degree of numerical control of China's heat treatment process equipment has been significantly improved. For more than 20 years, after competing with the well-known foreign brands such as Ai Xilin and Epson, the gear carburizing, heat treatment process and complete sets of equipment with Chinese characteristics have been formed. The market share of domestic heat treatment equipment has increased year by year. It has strong competitiveness. The box furnace and continuous furnace of FAW Jiaxin are the best in Xi'an Minsheng. In particular, the infiltration technology has attracted the attention of foreign companies.
Speaking of the gap between gear products and foreign advanced level, Wang Shengtang takes the main reducer spiral bevel gear as an example. It points out that except for the products of a few enterprises that reach or are close to the advanced level of foreign countries, most of the products of the enterprises are related to fatigue life and noise indicators. The gap between the advanced levels is large, and enterprises are trapped in vicious competition of low prices and low quality. And its quality level has an important relationship with the level of materials and heat treatment.
He said that the improvement in the quality of automotive gearbox products began with the study of control gear heat treatment deformation. From the heat treatment deformation control in the 1970s to the formation of vehicle gear steel procurement standards at the end of the 20th century, the gear industry has experienced a painful exploration process. Later, it has been proved that if the quality of the gear steel is not strictly controlled, and the heat treatment process control is simply studied, the problem of the automobile gear deformation cannot be solved. Wang Shengtang compares materials to the root of gear quality. Therefore, after more than 10 years of brewing, drafting and trials for a period of time, in 2004 the first standard of the Gear Professional Association was officially released – the vehicle gear steel procurement standard. Wang Shengtang said that from the implementation of gear steel procurement standards these years, the production level of automotive gearbox gear has been significantly improved. Therefore, we should continue to implement the gear steel procurement standards, recommend Class A steel for automobile gears, adhere to Class B steel, and phase out Class C steel.
The material is solved. After roughing, the next step is to carry out hot processing. Only after heat treatment can the hardness of the gear product be improved and the life and reliability can be improved. However, the heat treatment will inevitably lead to deformation of the product. How to control the deformation to the utmost is still a The world's problems, and China's heat treatment deformation control and foreign advanced level gap. Wang Shengtang pointed out that the deformation control of industrial gearbox gears is the basis of high-quality grinding gears, such as heavy teeth, NGC, Hangjin and other enterprises grinding 3~4 grade carburizing and quenching gears, for multinational companies, all are controlled Heat treatment deformation is based. Without good deformation control, there is no good grinding gear. If the grinding tooth covers the heat treatment deformation of the super deviation, the concept of geometric accuracy is wrong. Grinding tooth correction deformation can only be carried out within reasonable tolerances, otherwise the carburized layer will be destroyed and the smooth transition of the root circle will be unqualified.
System control from steel to heat treatment is also key. Wang Shengtang also cited the example of Dongguan Golden State. Dr. Wang Yong from Guangdong Jinzhou Company returned from the United States to control the forging heat treatment process by strictly controlling the quality of gear materials, and using the second-hand equipment to mass produce low-noise, long-life spiral bevel gears with noise control of about 70 decibels. The life expectancy is over 1 million times, which is close to the international level. The importance of system control has also been proven from his industrial practice, and these experiences are worth learning.
Wang Shengtang also emphasized that data accumulation is the only way to improve the level of heat treatment process control software. We use heat-treated CNC equipment to promote the improvement of heat treatment process level, and the accumulation of process data of heat treatment promotes the improvement of the level of heat treatment process control software. This is a complementary relationship. Many companies have their own valuable in the accumulation of heat treatment process data. Experience, this has also become a fortune for them. Why do some companies use the same equipment and produce the same products, but the quality level is high, which has a certain relationship with the accumulation of their process data and the level of heat treatment process control software.
In response to the existing problems, Wang Shengtang made three suggestions. First, gear companies should work closely with steel mills to continue to promote the further implementation of gear steel procurement standards. Second, each gear enterprise must form its own product heat treatment process software, form its own process know-how, and form its own product process specifications according to the characteristics of its own products. The heat treatment equipment enterprises should do a good job in the after-sales service on the basis of improving the numerical control level and control level of the equipment, and use the heat treatment equipment together with the users to the best. The third is the heat treatment equipment enterprise and the gear manufacturer to jointly study the complete set of equipment and process specifications for heat treatment; to make the general specifications of carburizing, quenching and heat treatment well, not only to standardize the configuration of numerical control equipment, but also to ensure the carburizing and quenching process. Stable.
In this regard, the Gear Professional Association has begun to work. At the symposium, the Gear Professional Association issued the “Notice on the Establishment of the Working Group for the Heat Treatment Process Specification of the Main Reducer Spiral Bevel Gears for Vehiclesâ€. Wang Shengtang said that it is called “Technology Research Team†or “Technical Specification Preparationâ€. "Working Group", although everyone is still controversial, but the goal is clear, that is, the vehicle main reduction spiral bevel gear as a breakthrough, standardize its heat treatment equipment and process control principles, and promote the vehicle main reduction spiral bevel gear heat treatment deformation control and fatigue life Meet the international vehicle support level.
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