What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
At present, with the development of the manufacturing industry, many parts with strange shapes are widely used in aviation, aerospace and other industrial fields, one of which is an L-shaped cylindrical pin. The upper end is provided with a 2.55×4.95 U-shaped boss. The parallelism error between the upper end face and the lower end face of the boss is required to be less than 0.01 mm. The L-shaped cylindrical pin requires high machining accuracy and is difficult to clamp on the machine tool. It is difficult to process. When the forming part is cut off, the cut surface, that is, the upper end surface of the boss, will leave a small column platform. When processing this end surface, in the prior art, a vise is generally used to process such an L-shaped cylindrical pin. Or copper sleeves are clamped, and then processed; however, due to the small size of the parts, the L-shaped cylindrical pin workpiece is difficult to clamp; due to the high precision required for each machined surface of the workpiece, when clamping with a vise , the clamping force of the vise is difficult to control, and it is easy to crush and scratch the surface of the workpiece; and when using a vise or a copper set clamp, only one workpiece can be clamped for each processing and production, and it is difficult to ensure the upper and lower planes of the parts after the clamping is completed. Parallelism machining error, resulting in low parts processing quality and low production efficiency.
The head of the traditional screw is located outside the threaded hole and occupies a large space, which is not suitable for occasions with small space, nor is it suitable for occasions where the outer surface of the component is a working surface. For example, in the field of electronic products, or when connecting the shaft and the shaft sleeve, the machine screw with a fully threaded structure on the outer surface is widely used.
At present, in the production workshop, there is no special tool for removing rivets such as skew, wrong rivets, and multiple rivets. When removing these rivets, workers use homemade rivet removal tools, use a sledgehammer to remove the rivet head, and then use a sharp tool to remove the rivet rod. eject. During the removal operation, sometimes the rivet head will fly out, the speed is high, the danger is extremely high, and the labor intensity is high, which has caused many industrial accidents.
The locking effect of the spring washer is general, and the important parts are used as little or not as possible, and the self-locking structure is adopted. For spring washers used for high-speed tightening (pneumatic or electric), it is best to use surface phosphating washers to improve their anti-wear performance, otherwise it is easy to burn out or open mouth due to friction and heat, and even damage the surface of the connected parts. For thin plate joints, spring washer construction should not be used. According to statistics, spring washers are used less and less in automobiles.
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