What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The screw refers to the screw (foreign name: Screw), which is a tool that uses the physical and mathematical principles of the oblique circular rotation of the object and the frictional force to gradually fasten the utensils and parts. A screw is a common term for fasteners, an everyday colloquial language. Metric threads are measured in MM (millimeters) and have a cusp angle of 60 degrees. Both US and Imperial threads are measured in inches. The cusp angle of the American thread is also 60 degrees, while the cusp angle of the imperial thread is 55 degrees.
The shaft circlip is a mechanical part installed on the slotted shaft and used as a fixed part for the movement of the hole. The inner diameter of the shaft circlip is slightly smaller than the mounting shaft diameter. When installing the shaft circlip, use the circlip pliers, insert the pliers into the pliers hole of the retaining ring, expand the retaining ring, and then put the shaft circlip into the shaft groove.
Most electrical appliance manufacturers only require the size and riveting gap to be tested for riveted contact components. There is no clear requirement for riveting strength. Only a few manufacturers perform torsion testing on riveting strength. The torque detection method is as follows: use a saw blade to open a one-shaped groove on the rivet head of the riveted contact element, and then insert a torque wrench into the one-shaped open groove to rotate, and measure the torque value. Because most of the electrical contacts are made of copper-silver alloy, the strength is low, and it is easy to slip during the test, and when a saw blade is used to open the one-shaped groove, the width and depth cannot be accurately positioned, so the measured value fluctuates greatly. , has always been an unsolvable technical problem in the industry.
The machinery industry is one of the main users of fasteners. Due to China's late understanding of the important position of mechanical basic parts in the machinery industry and a long-term lack of investment, the entire industry has a poor foundation, weak foundation and weak strength. Especially with the improvement of the level of the main engine in China, the bottleneck phenomenon that the mechanical basic parts lag behind the main engine has become increasingly apparent. Today, although the state has given certain support in technology introduction, technological transformation, scientific research and development, etc., there is still a big gap compared with the current market demand and foreign levels. Unstable quality, high early failure rate and poor reliability. Fasteners are the main basic products in the machinery industry, and the development of the machinery industry also puts forward higher requirements for fastener products. Domestic ordinary standard fasteners have always been in oversupply, while high-end fasteners (high temperature, special-shaped, titanium-plastic composite, special performance and other fasteners) are in short supply, and they also rely on imports. The State Machinery Bureau lists ordinary standard fasteners as restricted development products, and high-strength special-shaped fasteners as currently encouraged development products. With the improvement of the country's industrialization level and technological progress, the use of high-strength fasteners has gradually increased.
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