What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The flat key transmits torque on the side, has good neutrality, is easy to assemble and disassemble, and cannot realize the axial fixation of the parts on the shaft. Ordinary flat key: Type A, Type B, Type C, Type A is used for shaft grooves machined by end mills. The key is well fixed axially in the groove, but the stress concentration caused by the groove on the shaft is large; Type B is used for disc milling cutters. The machined shaft groove, the stress concentration of the shaft is small; the C type is used for the shaft end; it is suitable for high-speed, high-precision or occasions under variable load and impact, such as fixing gears, sprockets and other rotating parts on the shaft. Guided flat key: The key is fixed on the shaft with a screw, the key and the hub groove are in dynamic fit, and the parts on the shaft can move axially. For the convenience of starting the key, there is a key-starting screw hole. Use the occasions where the axial movement of the parts on the shaft is not large, such as the slip gear in the gearbox. Feather key: The key is fixed on the axle, and the parts on the shaft can move axially with the key; it is used in the occasions where the axial movement of the parts on the shaft is large;
At present, injection molding screws are widely used in various electronic and automotive components, including a body, the middle of which is provided with a through hole 3, the body head 1 has a hexagonal cross-section, and the tail 2 is provided with screw teeth. When in use, the middle through hole 3 of the body will first put the wire harness, and then fix it by injection molding from the head I, and the threads of the tail 7 should be connected and installed with other components. Because the head I of the main body is hexagonal, the torque provided after injection molding is insufficient. Therefore, after the external thread is installed and connected with other components, the head is prone to slip, the installation is not reliable, and there is no push-pull force, resulting in product failure and increased safety hazards.
Blind rivets are a type of rivets for single-sided riveting, but they must be riveted with a special tool - a rivet gun (manual, electric, pneumatic). This type of rivet is especially suitable for riveting occasions where it is inconvenient to use ordinary rivets (which must be riveted from both sides), so it is widely used in construction, automobiles, ships, aircraft, machinery, electrical appliances, furniture and other products. Among them, the open type oblate head blind rivets are the most widely used, the countersunk head blind rivets are suitable for riveting occasions that require smooth performance, and the closed blind rivets are suitable for riveting occasions that require higher load and certain sealing performance.
Iron two combination screws can be sucked up with magnets, but stainless steel two combination screws are difficult to be sucked up. Environmentally friendly three-combination screws and non-environmentally friendly ones are invisible to the naked eye and require mechanical testing. It cannot be judged with the naked eye and out of thin air. The specifications of the two combination screws need to be determined by the national standard. The salt spray of the two combination screws needs to be measured with a salt spray machine for how many hours.
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