What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Stainless Steel Nuts Hexagon Nuts (GB6170/DIN934), Thin Nuts (GB6172/DIN439), Heavy Nuts (Metric, US), Nylon Lock Nuts (DIN985-DIN982 Thick), All Metal Lock Nuts (DIN980M), Cap Nuts (DIN1587), Flange Nuts (GB6177/DIN6923), Flange Nuts Nylon Lock Nuts (DIN6926), Square Weld Nuts (DIN928), Hex Weld Nuts (DIN929), Butterfly Caps (GB62, DIN315, American), K cap, etc. Specifications: M1.6-M64
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.
Screws and bolts are common connecting fasteners. The diameter of the thread is as small as less than one millimeter and as large as several hundred millimeters or even larger. The vast majority of threaded connections are pre-tightened during assembly in order to enhance the rigidity, tightness, anti-loosening ability of the connection and prevent the sliding of the bolted connection under lateral load. The pre-tightening force is determined according to the force of the bolt group and the working requirements of the connection. For important threaded connections, the preload must be measured and controlled.
At present, when fastening parts on thin-walled products or thin plates in our country, screws are usually used to fasten, and welding nuts are required to make the thin plate easy to burn through, or the objects are drilled and tapped to connect, so that the product is deformed and the connection strength is not strong. , It cannot be fastened on some equipment, the operation is inconvenient, and the production efficiency is low.
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