What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The national standard for the size of the screws in the round head three-combination screw is GB818. The main technical requirements of various types are: iron and stainless steel for material requirements, low, medium and high carbon steel for iron, and stainless steel combination screws The materials are stainless steel 201, stainless steel 304 and stainless steel 316. The thread tolerance is 6G, and the mechanical properties of the iron combination screws are 4.8 and 8.8. The 4.8-level combination screws are ordinary steel, and the maximum allowable hardness is 255HV. The 8.8-level combination screws are generally made of wire rod 10B21. , and then undergo hardening treatment, and then dehydrogenation after hardening treatment. Hydrogen removal is to prevent hydrogen embrittlement of the spring washer in the combination screw. Prevent the spring pad from breaking. The tolerance class of the combination screws is A. The cross groove is H-shaped. The surface treatment of the combination screw has environmental protection and non-environmental protection. Such as, environmental protection blue zinc, environmental protection color zinc, black zinc, color zinc, white nickel and so on. The technical requirement of the combination screw for the spring washer is that the washer should be able to rotate automatically without falling off.
flat washer, an annular groove is formed on the outer side of the upper surface of the flat washer, and a sealing ring is embedded in the annular groove, at least five circularly equidistantly arranged cylinders are fixed on the upper surface of the flat washer, and the The upper surface of the flat washer is provided with a circular hole that communicates with its bottom, a collar is arranged in the circular hole, an upper circular ring is fixed above the collar, a lower circular ring is fixed below the collar, and the upper circular The diameter of the ring is the same as the diameter of the lower ring, the diameter of the collar is smaller than the diameter of the upper ring, the diameter of the collar is consistent with the diameter of the circular hole, and there are at least three equally spaced holes in the middle of the outer wall of the flat washer. A circular groove, the outer wall of the flat washer is fixed with at least three reinforcing blocks staggered with the circular groove, and the reinforcing blocks and the flat washer are welded into one piece.
The inch thread is the thread size marked in inch. According to the shape, it is divided into two types: cylindrical and conical; according to the tooth angle, it is divided into two types: 55° and 60°. The 1/4, 1/2, 1/8 marks in the thread refer to the diameter of the thread size in inches. One inch equals 8 cents, 1/4 inch equals 2 cents, and so on.
screw is a tool that uses the physical and mathematical principles of the circular rotation and friction of an object to fasten the mechanism of the object step by step. A screw is a common term for fasteners, an everyday colloquial language. Screws are indispensable industrial necessities in daily life: tiny screws used in cameras, glasses, clocks, electronics, etc.; general screws in televisions, electrical products, musical instruments, furniture, etc.; as for engineering, construction, and bridges, large screws are used. Screws and nuts; transportation equipment, airplanes, trams, automobiles, etc. are used together with large and small screws. Screws have important tasks in industry. As long as there is industry on earth, the function of screws will always be important. The screw is a common invention in people's production and life for thousands of years. According to the application field, it is the first invention of mankind.
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