What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
However, this process scheme has high cost, low efficiency, and has certain difficulties in quality assurance. In order to ensure product production efficiency, reduce manufacturing costs and improve product quality, it must be considered that the blank forming is completed on a multi-station cold heading machine at one time.
The earliest rivets were small pegs made of wood or bone, and the earliest metal variants may be the ancestors of what we know as rivets. They are without a doubt the oldest known method of joining metals, dating back as far as the earliest use of malleable metals, eg: Bronze Age Egyptians riveted the six wooden sectors of the outer lines of a slotted wheel with rivets Fastened together, after the Greeks had succeeded in casting large statues in bronze, the parts were riveted together with rivets.
However, although the existing screws can meet the function of connecting and fastening objects, they are all pressed against the object by the head to achieve the purpose of pressing and fixing. However, due to the small size of the head, it is difficult to press the object firmly. , for this reason, only spacers can be added to increase the pressing area. However, in the assembly process, the gasket is prone to slip off, and it needs to be supported by hand, which brings inconvenience to installation and use; at the same time, sometimes the object to be pressed is only on one side of the screw, and the other side of the screw does not need to be pressed. This results in unnecessary waste of materials, and also occupies a certain space, which brings trouble to the installation of other components.
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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