Hu Jintao is very concerned about the impact of the international financial crisis on the production and operation of enterprises, and went to the two large enterprises in Harbin for inspection.
Hu Jintao, together with the Harbin Measuring and Cutting Tool Group Co., Ltd., is the leader of the industrial tool industry in China. Hu Jintao analyzes the situation and finds countermeasures. He pointed out that only by vigorously developing independent technologies, while strengthening the introduction, digestion, absorption and innovation, can we continuously enhance the competitiveness of enterprises. We must see opportunities from difficulties, increase research and development efforts, focus on tackling key problems, strive to master more core and key technologies, and make good technical reserves to lay the foundation for better development in the future.
Harbin Aircraft Industry Group Co., Ltd. is the birthplace of China's first helicopter. Hu Jintao walked into the helicopter assembly shop to learn more about the technical design of various types of helicopters produced by the company. The focus was on improving the ability of independent innovation to discuss with everyone. The general secretary told everyone that independent innovation is the key to enhancing the competitiveness of enterprises. I hope that you will increase scientific and technological research and development, strive to master the advanced technology in the world, continuously improve its core competitiveness, and make new contributions to the development and expansion of China's aviation industry.
Because of its self forming or tapping the thread matching it, it has high anti loosing ability in combination and can be disassembled. In the small screw, its size, thread type, head type, drilling performance, in the engineering use of high tension, single, unilateral combination features almost unlimited. Self tapping materials can be divided into carbon steel and stainless steel, of which 1022 medium carbon steel is the main material.
1: According to the different head, it can be divided into: round head, flat head (i.e. countersunk head), top stigma, round top wide side head, big round head (i.e. big flat head), hexagon bearing hole head, hexagon bearing hole Huasi head, hexagon bearing hole Huasi head
Round head: it is the most commonly used head shape in the past
Flat head: it can replace the new design of round head and mushroom head. The head is low in diameter, and the peripheral circumference of the head is connected with the high edge of the characteristic, which makes it play a driving role for high-strength torque. It is slightly different from the hole head in head shape
Top column head: the diameter of the standard flat round top column head is smaller than that of the round head, but it is higher due to the groove depth. The smaller diameter increases the pressure acting on a small area, and can be closely combined with the flange and the increased surface layer. As the head is made in the drilling die set to ensure the concentration, they can be successfully applied to the holes in the internal drilling
Dome wide side head: due to the undercutting of the head to restrain and reduce the wear of the wire components, it is most commonly used in electrical appliances and tape recorders, providing an attractive design type for the middle and low head type with its more sufficient bearing surface
Big round head: also known as oval top wide edge head, is a low type, cleverly designed large diameter head. When the combined tolerance of additional function allows, it can be used to cover the metal plate hole with larger diameter. It can also be recommended to use flat head instead
Hexagon socket head: a kind of joint with the height of wrench head and the size of hexagon head. The hexagon is completely cold formed by the reverse hole mold, and there is an obvious depression at the top of the head
Hexagon socket head: such as the standard hexagon socket head, but at the same time, there is a socket face on the base of the head to protect the assembly from damage of the wrench. Sometimes the function of things is far more important than appearance
Hexagon head: This is a standard type of torque acting on the hexagon head. It has the feature of trimming sharp corners close to the tolerance range. It can be recommended for general commercial use. It can also be applied to various standard patterns and various thread diameters. Because of its necessary second process, it is more expensive than general hexagon socket
2: According to the groove type, there are four types: slotted head type (also called slotting), cross slotted head type, cross slotted head type, cross slotted compound slotted head type and meter slotted head type
3: According to the standard can be divided into: GB, DIN, ANSI, BS
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