What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Bolts refer specifically to screws with larger diameters and may also have no heads, such as stud bolts. In general, it is not called a stud bolt but a stud stud. The most common form of stud is threaded at both ends and a polished rod in the middle. The most typical use: anchor bolts, or places similar to anchor bolts, thicker connections, when ordinary bolts cannot be used.
Generally, the T-bolt structure is common, and its blank shape can be completed at one time on a multi-station cold heading machine. But for T-bolts with relatively rare structures, (for example: the intersection of ¢14x42 cylinder (head) + ¢12 cylinder, the two cylinders form a 90° intersection) due to the special structure, the head Cold forming is difficult, and the traditional processing route is: die casting blank → deburring → turning processing → grinding blank diameter → wire rolling → heat treatment → surface treatment → finished product packaging.
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.
The square nut is a fastener that needs to be used in the installation of the cable tray. In the prior art, the square nut 1 is pressed by the elastic force of the spring 2 below it and the opening of the C-shaped steel 3 (as shown in Figure 1, Figure 2), in the absence of external force, through the interaction of pressure and static friction, the C-shaped steel 3 will not move vertically or horizontally, which can facilitate engineering installation. The advantage of this installation method is that it can slide anywhere on the C-shaped steel 3, but the disadvantage is that it occupies the bottom space of the C-shaped steel 3, and the spring 2 will interfere with the installation hole of the square nut I, which affects the installation.
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