What is the specific use of bolt connection with washer?

What is the specific use of bolt connection with washer?  The second is to increase the contact surface, in order to prevent stress concentration this is not a fixed rule, flat pad is added on both sides, the bolt hexagonal head and bolt rod transition have large chamfer, the main design requirements;  Third, the stable friction coefficient.  The spring mat is mainly to prevent loose, and is added at the end of the screw.  But there are rules to follow, one is to adjust the height:  

1. Screw the nut on the side of the nut, so that the chamfered side of the washer can be put on the hex head of the bolt to avoid, and the flat washer in the tightening is not allowed to turn, it is convenient to add it on the bolt or nut.  

2, the screw hole chamfer is small;  Four is to prevent the pull bolt, flat pad at both ends of the more.  There are several functions of the flat washer. The screw bolt is on the side of the bolt. If the head is pulled after tightening the bolt, it will be damaged.  What role does the washer play in the bolt connection?  

First, the role of the flat washer in the bolt connection  

In the case of frequent removal of bolts, in order to protect the surface of the connecting piece from scratches, the general need to place a flat washer in the nut or bolt head position, so that you can prevent the surface of the connecting piece from scratches.  

In some require more accurate joint friction coefficient, such as high strength prestressed bolts are placed flat washer need nut end, in this condition, bolts, nuts, washers are provided by the same manufacturer, bolt manufacturers need to corresponding processing of nut and washer, to ensure the consistency of the friction coefficient between the nut and washer.  

When the bolt strength is high and the allowable compressive stress of the connected part is low, in order to reduce the compressive stress of the bearing surface of the connected part, it is generally necessary to add a flat washer.  

In the bolt connection, the pressure transfer of the bearing surface of the bolt head or nut is gradually expanded in the shape of a horn. The larger the bearing surface is, the smaller the compressive stress is. Therefore, the flat washer can be added to reduce the compressive stress of the contact surface of the connected parts to ensure the effective bolt connection.  

In some cases, in order to ensure that the bolt holes between the two connectors can be one to one, we need to increase the diameter of the hole to compensate the position of the hole deviation, the bolt hole exceeds the standard requirements need to increase the flat washer.  

Sometimes in order to facilitate installation and adjustment, the bolt hole will be made into a long hole, so that the installation position of the workpiece can be adjusted within a certain range. When the long hole is used, the thickened flat washer must be used, more specific, and even the use of special gaskets or multiple gaskets.  

The role of spring washers in bolt connections  

The main purpose of the spring washer is to relax, generally used for the bolt pretightening force is not high, and the dynamic load is small occasions.  

When the bolt clamping length is short, the bolt stress relaxation is obvious, and the spring washer can compensate for the stress relaxation.  

Some experiments show that under dynamic load conditions, high-strength bolted spring washers have almost no anti-loosening effect, but also cause the rapid attenuation of bolt clamping force, so there are few foreign spring washers used in high-strength bolted connection.