What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The screw is usually installed in the threaded hole of the part, and its main function is to fix the relative position between the two parts. It is widely used in various industries. A traditional screw generally includes a screw rod and a head located at one end of the screw rod. During installation, the screw rod is connected with a threaded hole, and the head is located outside the screw hole and abuts on the edge of the screw hole.
Generally, the countersunk head is used in places where the surface is required to be smooth without protrusions, because the countersunk head can be screwed into the part. Round heads can also be screwed into parts. The tightening force of the square head can be larger, but the size is large. In addition, in order to meet the needs of locking after installation, there are holes in the head and holes in the rod. These holes can prevent the bolts from loosening when they are vibrated. Some bolts without threads should be made thin, called thin-waisted bolts. This kind of bolt is beneficial to the connection under variable force. There are special high-strength bolts on the steel structure, the head will be larger, and the size will also change. In addition, there are special uses: for T-slot bolts, which are most used on machine tool fixtures, with special shapes, and both sides of the head should be cut off. Anchor bolts, used for machine and ground connection and fixing, come in many shapes. U-bolts, as previously described. and many more. There are also special studs for welding. One end has a thread and the other end is not. It can be welded to the part, and the other side can directly screw the nut.
In the existing joint replacement, self-tapping screws are mostly used, and their triangular thread structure has a certain self-locking ability. After a long period of service, it is prone to loosening. The surrounding bone may not be tight enough after implantation, resulting in a sharp decline in its self-locking ability, and there may be a risk of regression, causing certain damage to the human body.
Screws are a kind of fasteners commonly used in machinery, but most of the screws commonly used in the market are standard parts. The screws themselves are ordinary and have no function of preventing loosening and protecting the matrix. Therefore, in order to prevent the screws from loosening during use , Usually it is necessary to configure additional elastic washers, flat washers, etc. that are suitable for screws, and these elastic washers and flat washers are mostly metal products. During use, it is easy to wear with the body base and damage the protection of the sheet metal base. After long-term use, metal washers are easy to rust, which affects the tightening effect and appearance of screws. In addition, the use of metal washers not only increases the weight and cost, but also the assembly process is complicated and cumbersome, and the anti-loosening and anti-wear effects are not ideal. .
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