What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The necked brake pad rivet includes a head and a shaft, the head and the shaft are integrally connected, and it is characterized in that: the head and the shaft are provided with axial through holes formed by cold heading, so The end of the shaft is provided with a tapered portion formed by cold extrusion and chamfering.
A pin and a pin piece inserted on the pin, the width of the pin piece gradually decreases from the insertion end to the other end, and the pin piece is also provided with a protrusion, the protrusion is a triangular ratchet tooth shape, the An insertion hole is arranged on the pin, and a pawl corresponding to the protrusion is arranged in the insertion hole.
The history of screws was broadcast in 1986. Our country formulated a new standard for standard parts, which is commonly known as the new standard in the business. The most used ones are GB5780, GB5781, GB5782, GB5783, GB5784. GB5780 is a hexagonal head thick shank half-thread screw, its accuracy grade is C-grade product, which can be replaced by GB5782 (GB5782 is a hexagonal head thick shank full-thread screw, and its accuracy grade is grade A and B.) GB5781 is a hexagonal head full-thread screw. Threaded screw, the accuracy grade is C grade product. It can be replaced by GB5783 (GB5783 is a hexagonal head full-tooth screw, and its accuracy grades are A and B). GB5784 is a hexagon screw with thin rod and half teeth.
At present, with the development of my country's railway industry, many railway fastener systems involve T-bolts. The structure is shown in Figure 1. The dimensions that need to be inspected are head width A, head length B, and head straight table height. C. The height of the head slope D, the total length of the bolt E, and the major diameter of the bolt F. Due to the irregular shape of these places to be inspected, the measurement is difficult. The measurement of general measuring tools is not only slow, but also difficult to control human errors, resulting in some extreme upper limits and There are disputes and misjudgments about the size of the extreme lower limit when judging qualified and unqualified.
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