2. In order to eliminate the damage of the spring pad to the machine surface when removing the screw, the flat pad must be matched. It must be a spring pad and a flat pad when used. The flat pad is next to the machine surface, and the spring pad is between the flat pad and the nut.

3, need to use elastic pad when locking.

Extended data

A screw is only equipped with a spring pad or a flat pad, or it can be equipped with a two-piece assembly with only one flower tooth. The national standard number of combined screws is indicated by GB9074. The national standard number of commonly used cross-grooved small pan head triple combination screw is GB9074.8.

The materials of combined screws are divided into iron and stainless steel.

High-strength large hexagon-head bolt combination screws for steel structures are mainly used in railway and highway bridges, boiler steel structures, industrial workshops, high-rise civil buildings, tower mast structures, hoisting machinery and steel structures where friction-type high-strength bolt combination screws are needed.

Characterized in that the end of the bolt is provided with a dodecagon, which is also called a bolt. When installing, a special electric wrench must be used, with two concave heads at the top and bottom, one on the hexagon of the nut and the other on the ten corners of the external hexagon screw.

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