What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Round head three-combination screw The screw size in the round-head three-combination screw is GB818, and the main technical requirements of various types are: iron and stainless steel material requirements, iron low, medium, high carbon steel, stainless steel combination The materials of the screws 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.
The flat screw mainly includes a rotating part and a screw locking part, wherein the rotating part and the screw locking part are respectively flat-shaped structures; At least two sides of the screw lock portion are respectively provided with tooth rows, and the two tooth rows are mutually dislocated, so that the screw lock portion can be locked in a pre-formed screw hole in the workpiece.
The rivet nut is a kind of nut applied to thin plate or sheet metal. The principle is to press the embossed teeth into the preset holes of the sheet metal. Generally, the diameter of the square preset holes is slightly smaller than the embossed teeth of the pressure riveting nut. The periphery of the hole is plastically deformed, and the deformed object is squeezed into the guide groove, thereby producing a locking effect. The pressure riveting nut is divided into free-cutting steel pressure riveting nut S type, stainless steel pressure riveting nut type CLS, stainless iron pressure riveting nut SP type and copper and aluminum pressure riveting nut CLA type, which should be used in different environments. . Generally speaking, the national standard domestic products without rivet nuts from M2 to M12 are PEM specifications, which are usually produced in chassis cabinets and sheet metal industries.
In view of the above problems, Guangdong Yueluo Hardware Industry Co., Ltd. aims to provide a new type of open blind rivet suitable for riveting of aluminum, steel and stainless steel sheets with foamed materials.
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