The screws on doors and windows can be divided into cylinder head, half countersunk head, countersunk head, cylinder head, hexagon head, not to mention, there are many thread styles just according to its head shape.
Expansion screw: Expansion is not as literally imagined. After the screw is screwed, it will suddenly expand to strengthen the connection strength. The principle of the expansion screw is to move the screw thread so that the expansion tube forms a great pressure on the surroundings to achieve a fixed effect.
Compared with ordinary screws, its drilling is small, the pulling force is large, and it can be removed at will, so it frequently appears in every corner of our life, but it is also prone to mistakes. Pay special attention to the depth of the hole when installing, whether it is deep or shallow. , Will affect its fixed ability.
Self-tapping screw: This name has already given a good definition of its ability-good at self-attack. Compared with the ordinary screw, the "flat-headed kid", the self-tapping screw is a "stab head".
Its sharp-angled shape allows you to drill directly into the profile without drilling holes in the profile. Just listening to it is amazingly lethal. High texture, high strength, and strong corrosion resistance (mostly exposed) make it one of the giants in one fell swoop. Finally, there are the self-drilling screws.
Its characteristic is that the tail is drilled or pointed, no auxiliary processing is required, and the material can be drilled, tapped, and locked directly. All the procedures are completed in one go, which greatly saves the construction time.
Compared with ordinary screws (the gun is lying down again), its toughness and holding power are high, and it will not loosen after a long time after combination, and its stability is higher.
The characteristics and differences between self-tapping screws and self-drilling screws are located at the tail.
The tail of the self-tapping screw is pointed, coarse and hard with a certain taper, but it cannot be drilled. The threaded head of the self-tapping screw is like a drill bit that can be drilled. Easy to distinguish.