What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
hand screw is a screw with a plastic head, and the user fixes the hand screw by turning the plastic head by hand. At present, a hand screw is disclosed in the market publication number CN202203253U, which includes a plastic head and a screw rod, the plastic head and the screw rod are connected together, and the height of the plastic head is higher than that of an ordinary screw, and the height is 12 cm. The screw of the hand screw is fixed in the plastic head by glue. After a period of use, the aging of the glue leads to the loosening of the screw and the plastic head. When the plastic head is stressed, the screw rod comes out of the plastic head, which affects the normal use of the hand screw.
Referring to Figure 1, one end of the existing insert nut 1' is embedded in the injection molded part 2', and the other end is exposed to the injection molded part 2'. The insert nut 1' has opposite lower and upper end surfaces in the axial direction. The end face of one end of the insert injection molded part 2' is the lower end face. In order to reduce the resistance during hot pressing, the connection between the inner wall surface and the lower end surface of the insert nut 1 ′ is provided with an inclined surface. However, when the embedded nut 1' of this structure is hot-pressed, the hot melted glue will generate a shunt that rises along the slope, and then a convex peak is formed in the screw hole of the embedded nut 1', and the convex peak occupies the screw. The space in the hole prevents the screw 5' from being completely screwed in; at the same time, due to the shunting of the hot solder, the knurling of the inner nut 1' near the upper end face cannot be filled with the solder, which makes the inner nut 1' and the inner nut 1' and The injection part 2' is not firmly embedded. Therefore, the locking strength of the existing insert nut 1 ′ and the screw 5 ′ after being hot-pressed is relatively low.
At present, many manufacturers do not want the product to be disassembled by the user, so they set the anti-disassembly mark on the product. The common method is to apply red or blue anti-disassembly paint on the fastener, such as the nut, once the user disassembles it by himself. , the paint at the connection will fall off, and it can no longer be aligned, so that the manufacturer can judge and identify it and provide a basis for warranty. However, it is inconvenient to paint some joints, and the use of tamper-evident paint is not healthy and environmentally friendly.
The nut is based on the reaction force principle of the inner hexagonal cone of the clamping part and the outer hexagonal cone of the locking part. The higher the pressure, the tighter the lock, so that the bolt can achieve the purpose of self-locking and tightening. The existing bolts rely on multiple nuts against each other to prevent loosening. This method cannot be completely locked, and the bolts are easily loosened when subjected to huge pressure and vibration, which hides potential safety hazards;
The above content is uploaded by Yueluo or the Internet. If there is any copyright issue, please contact [email protected].
