What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
screw with a gasket includes a screw head and a screw connection part connected with the screw head, the screw connection part is provided with a thread, and a transition part is provided between the screw head and the thread provided on the screw connection part , the diameter of the transition part is smaller than the diameter of the thread, the transition part is sleeved with a plastic washer, the inner ring of the plastic washer is a polygon, and the diameter of the inscribed circle of the inner ring of the plastic washer is smaller than the diameter of the thread. The utility model replaces the traditional metal washer with a plastic washer, which avoids the phenomenon that the washer causes wear on the connection base. The inner hole of the plastic washer adopts a polygonal design, and the diameter of the inscribed circle of the inner ring of the plastic washer is smaller than the diameter of the thread, which is in the same shape as the thread. The multi-point contact solves the problem that the washer is easy to slip off due to the circular design of the inner hole of the traditional metal washer, and improves the assembly efficiency of the screw.
In view of the deficiencies of the prior art, a simple structure is provided, which can ensure that the nut body and the washer are assembled together during the production of the wheel nut, and will not be separated from each other in any occasion, so as to ensure the reliability of the assembly, and the nut will no longer appear. The wheel nut assembly that needs to be reassembled after use or placement saves time and effectively improves the convenience of the wheel nut when it is used or placed
A low-carbon steel rivet nut fastener composed of a brim, a deformed skirt and a threaded wire hole is characterized in that there are fish teeth below the brim; the outer side of the lower end of the threaded wire hole has a chamfer; the inner wall of the threaded wire hole The cross section of the thread is an isosceles trapezoid, and the upper bottom of the trapezoid is a concave arc.
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.
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