Production of U-shaped card U-shaped bolts galvanized U-shaped water pipe card 1/2-13 1/4-20

High-strength fastener materials mainly include ML35, 35K, ML40Cr, ML35CrMo steel, etc., of which 75ML35CrMo steel is imported. The main problems of the material are box segregation, decarburization, cracks and so on. The material needs to be spheroidized and annealed before cold forming, and the annealing is carried out in an oil furnace. There is no protective atmosphere in the furnace, and there is a decarburization phenomenon. 1.2 The high-strength fasteners, mainly grade 12.9, are quenched and tempered on the chain casting furnace production line. The temperature and atmosphere in the furnace are controlled by computer, and Rx gas is used as a protective atmosphere. Heating and anti-oxidation and decarburization can be effectively controlled, and the quality of the fasteners is intact during the heating process. The high-strength fasteners mainly of grade 8.8 are quenched and tempered on the vibrating hearth furnace. Affected by the structure of the vibrating hearth furnace, the sealing performance of the furnace is poor, the Rx atmosphere is not easy to control, the temperature difference of the furnace is large, and the parts are heated in the furnace. The collision and the length of time are inconsistent, and the quality of the fasteners during the heating process is poor, and there are phenomena such as decarburization, bumps, and uneven heating.

Since the sub-industrial revolution, electricity has been widely used in people's lives. The application and development of electric power liberates the social productive forces and improves the social production efficiency. It is indispensable to the progress of the society. As a necessary constituent element of electric equipment, screws play an important role in the field of electric equipment. Existing screws are composed of screw heads and studs, which require specific tools to be tightened. However, during the maintenance of electrical equipment, some high-altitude workers need to carry extra screws in order to tighten the screws. the tightening tool, the staff caused great inconvenience.

Existing wood screws are composed of a threaded portion with a tapered angle and arranged along a tapered stem and a screw head. The head of the screw can be a countersunk head, hemispherical, or other shapes, and the head of the screw has a groove that fits with the tool, a word groove, and a concave cross groove. The taper angle of existing wood screws is either 45 degrees or 60 degrees, and the front end of the taper angle is a pointed point formed by a rotating thread. The existing wood screws have the following three deficiencies in use. Because the taper angle is 45 degrees or 60 degrees, and the thread angle is 64 degrees, the resistance when entering the material is relatively large, so the existing wood screws are manually screwed. It is difficult to screw in, especially when it is used for hardwood materials, and it often happens that the groove of the screw head is screwed out; A large lateral moment will be formed when the screw is screwed, which is prone to the problem of deviation from the position; in addition, because the existing screw is tapered, it will be subjected to both radial force and axial force when entering the material, and its stress state It is more complicated, so it is easy to cause the cracked wood material to burst, and even cause the material to have longitudinal cracks and be unusable.

The traditional single-sided riveting process mainly adopts two methods: rivet nut connection and blind rivet connection. The efficiency of the rivet nut is low. If the hollow nut is used, the rigidity is insufficient, resulting in low connection strength. In addition, the torsion resistance of the rivet nut is low. If the rivet nut is used to obtain better torsion resistance, it is made into a hexagonal shape. Embedding, because the shape of the sheet metal opening also needs to be made into a corresponding hexagon, it is inconvenient to process.

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