Specification and function of basic fastener knowledge

Basic knowledge of fastener products (Function)

I. Function:

1, screw torque requirements: the external hexagon screw to bear the torque is relatively larger, the inner hexagon screw to bear the torque is smaller, the cross groove torque is smaller (so this kind of screw is generally ordinary grade screws).

2. The assembly of external hexagon bolts shall generally be assembled with adjustable spanner, box spanner and open spanner.The assembly efficiency of adjustable wrench is low, but its versatility is strong. It is suitable for all kinds of hex screws with different head specifications.The efficiency of the box wrenches is the highest, but it is not suitable for some occasions. A box spanner has only 2 heads, so it can only be used on the outer hexagon screws with the heads of two specifications.An open spanner is similar to a box spanner, but it can be used with an extended sleeve.The smaller the specification of the outer hexagon screw, the higher the requirement for the angular Angle of the outer hexagon bolt, or its head will slip easily when subjected to (wrench) force.Wenzhou people in order to save material, invented the outer hexagon recess.Concave hexagon screw single weight, the thickness of the head is thinner, easy to slip, the head may also be screwed out.

3. Inner hexagon screws shall be assembled with inner hexagon wrench.This internal hexagonal hole requirements are very high, the hole a bit bigger wrench slip, a bit smaller wrench can not be inserted into.The smaller the hexagon, the higher the requirement for the hole.For some large inner hexagon screws, the inner hexagon as long as there is a qualified side, with a wrench can be normally assembled;To a few specifications small hexagon socket screw, such as M2 hexagon socket set, wrench inserted into a little force hexagon socket will slip, so a little bit on the side of a big unqualified.Therefore, the socket head screws M2, M2.5 and M3 (especially for fixed products) are easy to slip during the assembly process.

4, the cross groove screw with screwdriver assembly, do not need to use too much, so the strength as long as 4.8 can, occasionally some need high strength screws, as long as the carburizing heat treatment can