We sometimes use combination screws in our lives, but do you know anything about combination screws? Maybe people nowadays rarely understand the combination screw. If you don’t understand, you can read this news.

Combination screw Combination screw refers to the combination of a screw with a spring washer and a flat washer by rubbing the teeth to fasten them together. The two-component screw refers to a two-component screw with only one spring washer or only one flat washer, or it can also be equipped with only one tooth. The national standard number of the combined screw is represented by GB9074. The national standard of the commonly used cross recessed small pan head three-combination screw is GB9074.8. This .8 refers to the small pan head. This is the size of the head of a pan-head screw. Expressed in letters as PM. For professional combination screw manufacturers, the customary method of expression is Sanhe PM. The commonly used cross recessed large pan head combination screw national standard is GB9074.4. Professionally called a combination screw with a large pan head. Or R head, or B head. In other words, the head of this combination screw is larger and thicker than the head of the small pan head combination screw. There is also a commonly used one is the external hexagonal combination screw, this is the cross external hexagonal combination screw. It is often called the socket-outside hexagonal combination screw. The national standard number is GB9074.13.

High-strength large hexagonal head bolt combination screws for steel structure, mainly used for railway and highway bridges, boiler steel structures, industrial plants, high-rise civil buildings, tower mast structures, hoisting machinery and their steel structures require friction-type high-strength bolt combinations In the case of screws. It is characterized by a bolt, which is called a dodecagon at the end of the bolt. When installing, you must use a special electric wrench with two socket heads on the top and bottom, one is sleeved on the hexagon of the nut, and the other is sleeved on the decagon of the outer hexagonal screw. When tightening, apply a clockwise torque to the nut and apply an equal counterclockwise torque to the dodecagon of the bolt, so that the end of the hexagonal screw and the neck of the dodecagon are subjected to torsion shear until the neck is sheared. So far, the installation is over. This torsion-shear type high-strength hexagonal screw is a one-time use screw, and generally cannot be removed after installation.

This is the introduction and purpose of the combination screw.