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.
In the riveting connection of various structural parts, waterproof lantern rivets have been widely used in riveting environments that require waterproofing. After the riveting parts are riveted, the waterproof structure area of the mandrel and the waterproof structure of the rivet body There is no complete close fit between the areas. In some riveting ranges, the waterproof performance of the rivet is affected. The main reason is that the traditional processing technology of the mandrel and the materials used bring many troubles to the riveting process. is a problem to be solved at present.
When used for the connection and fixation of doors, windows, cabinets, etc. involving hinges, the traditional screw fastening method is usually used, and the screws are directly driven into the screw holes of the connected parts, and the screw end caps are directly exposed, which not only affects the connected parts. Moreover, the end caps of the screws exposed for a long time are easy to rust, and there are burrs in the end processing of the general screws. When used for fastening connections, the end caps of the screws are easy to scratch people, which affects the appearance and is not safe.
From the perspective of use: The bolted connection of the main components of the building structure is generally connected by high-strength bolts. Ordinary bolts can be reused, but high-strength bolts cannot be reused. High-strength bolts are generally used for permanent connections. The high-strength bolts are prestressed bolts. The friction type uses a torque wrench to apply the specified prestress, and the pressure type screw off the torx head. Ordinary bolts have poor shear performance and can be used in secondary structural parts. Ordinary bolts just need to be tightened. Ordinary bolts are generally 4.4, 4.8, 5.6 and 8.8. High-strength bolts are generally 8.8 and 10.9, of which 10.9 is mostly. Level 8.8 is the same level as 8.8S. The mechanical properties and calculation methods of ordinary bolts and high-strength bolts are different. The stress of high-strength bolts is firstly by applying a pre-tension force P inside, and then generating frictional resistance on the contact surface between the connected parts to bear the external load, while ordinary bolts directly bear the external load.
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