What kinds of screws are there?

1) slotted ordinary screws

It is mostly used for connecting smaller parts. It has pan head screws, cylindrical head screws, semi-countersunk head screws and countersunk head screws. The screw head strength of pan head screws and cylindrical head screws is higher, and the shell is connected to the ordinary parts; The head of the semi-countersunk head screw is curved, and its top is slightly exposed after installation, and it is beautiful and smooth, generally used for instruments or precision machinery; Countersunk screws are used where the nail heads are not allowed to be exposed.

2) Hex socket and hex socket screw

The head of this kind of screw can be buried in the member, can apply greater torque, high connection strength, and can replace hexagonal bolts. It is often used for connections requiring compact structure and smooth appearance.

3) Common screws with cross grooves

It has similar function with slotted ordinary screws and can be replaced with each other, but the groove strength of the cross groove ordinary screws is higher, it is not easy to screw bald, and the appearance is more beautiful. When used, it must be loaded and unloaded with the matching cross screw.

4) Ring screw

The lifting ring screw is a kind of hardware accessory for bearing weight during installation and transportation. When in use, the screw must be driven to the position that the supporting surface is closely fitted, and no tool is allowed to tighten it, nor is it allowed to have a load perpendicular to the plane of the lifting ring.

5) Tighten the screw

Setting screws are used to fix the relative positions of the parts. Screw the tightening screw into the screw hole of the part to be tightened, and press its end on the surface of another part, that is, fix the former part on the latter part.

The setting screw is usually made of steel or stainless steel material, and its end shape is conical, concave, flat, cylindrical and stepped. The end of the cone end or the concave end of the screw is directly jacking the part, which is generally used for the place where it is not often removed after installation; The end of the flat end setting screw is smooth, the top tightening does not damage the surface of the part, and is used for the connection where the position is often adjusted, and only small loads can be transferred; Cylindrical end tightening screw is used in the need to adjust the fixed position, it can bear a large load, but the anti-loosening performance is poor, the need to take anti-loosening measures when fixed; Step setting screws are suitable for fixing parts with large wall thicknesses.

6) Self-tapping screws

When the tapping screw is used on the connected part, the thread can be made without advance at the connected part. Tap the thread directly with the screw when joining. It is often used to join thin metal plates. There are two kinds of cone-end self-tapping screws and flat-end self-tapping screws.

7) Self-tapping locking screws

Self-tapping locking screw not only has self-tapping effect, but also has low screwing torque and high locking performance. Its thread is triangular section, the surface of the screw is hardened and has a high hardness. Its thread specifications are M2 ~ M12.