Take the automobile as an example. At present, most of the automotive fasteners have been localized, including 10.9, 12.9 grade high-strength bolts and some high-precision bolts. It seems that China has a strong ability in this area.
Today, we will lead you to understand the current situation and Prospect of China's fastener industry from bolt technology, testing, tightening and other aspects.
The typical main production process of fasteners is, first of all, steel production in steel mills. This work is mainly completed by large state-owned steel mills in China. At present, the production level of large steel mills in China, such as Baosteel, Xinggang, Nangang, Jigang and Zhongtian special steel, has been very high, and the stability of steelmaking and cold drawing technology has been able to meet the production requirements of most fasteners. At present, China's fastener manufacturers are also purchasing from these steel plants.
The steel wire produced by iron and steel plants needs cold heading to become the initial shape of fasteners. The most critical factor for the production of high-performance fasteners is the accuracy of cold heading machine. At present, the high-precision cold heading machines in China are not domestic, and are basically monopolized by Germany and Japan.
Therefore, China's fastener supplier is only a foundry, without high-end equipment manufacturers, and has not mastered the core technology at present. Therefore, our technology needs to strengthen technology research and development.
After cold heading, the thread of fastener needs to be twisted to form the rod thread. The key equipment is the thread rolling machine. At present, most of the domestic thread rolling machine can basically meet the production requirements, but the wear resistance life of the thread rolling machine needs to be further improved. In addition, the requirements of ultra-high precision and some special tooth shape, domestic thread rolling machine is still unable to meet the requirements, the basic monopoly of Europe and the United States.
In order to achieve a certain strength, the parts after rubbing must be heat treated. Heat treatment plays an important role in the mechanical properties of fasteners. But at present, the domestic heat treatment machine temperature control performance is still not up to the level of process manufacturers, so the equipment is basically monopolized by foreign countries.
In order to achieve a certain anti-corrosion performance, the surface of fasteners after heat treatment needs to be electroplated and coated with zinc and aluminum. At present, there are many electroplating factories and zinc aluminum coating factories in China. The coated products can basically meet the anti-corrosion requirements of high-performance fasteners;
At present, many domestic fastener manufacturers have established their own electroplating process lines, and their level is also very high. However, the electroplating or coating chemicals are rarely made in China, which are basically monopolized by foreign manufacturers such as ammett, jumeite and kouteya, and the chemicals are the most profitable ones for surface treatment.
Gluing of fasteners
In order to further improve the anti loosing or sealing performance of fasteners after surface treatment, gluing is one of the methods. The core technology of gluing is glue. At present, glue is monopolized by European and American countries. Manufacturers in China are only agents. By authorizing gluing manufacturers to earn huge profits, fastener manufacturers have to go to specific gluing manufacturers for gluing, because they have no choice.
After production, fasteners need to be tested according to the standard. Taking friction coefficient as an example, the testing level of domestic fastener manufacturers is very high. But the test equipment is a lot of foreign imports, such as ziwic friction coefficient machine, the test accuracy and convenience are very good, but the price is relatively expensive.
Tightening of fasteners
The fastener after passing the test needs to be tightened on the corresponding parts according to the process requirements by tightening equipment. At present, the tightening equipment of the mainstream manufacturers are all the equipment of horse head, Atlas, Bosch and other foreign manufacturers, but the domestic manufacturers are few, and the equipment prices of these manufacturers are high. There is still a big gap between China and foreign countries.
After the above thoughts, do you find that even if it's just a small screw, the whole independent supply chain of our country is still very imperfect, and there is still a big gap between us and foreign countries. Therefore, we must strengthen our independent R & D capability, and constantly narrow the difference between us and developed countries through time.