Design knowledge of shaft pin parts

Axle pin parts are usually used for bearings after processing. In the bearing industry, some people call them needle rollers or rollers. Generally, many people think that this should be a manufacturer of bearings. This is the only way to do this. In fact, it is not. A precision parts processing company like us can also do it. Not only can it be done, but it can be done very well. Today we will introduce the design concept and prior knowledge of the shaft pin exhausted parts. .

Shaft pin components usually exhibit delayed fracture under stress. There have been galvanized parts such as automobile springs, washers, screws, leaf springs, etc., which fractured within a few hours after the assembly of the shaft pin parts, and the fracture ratio reached 40% to 50%. The cadmium-plated parts of a special product had cracks and fractures in batches during the use process, and a nationwide research was organized to formulate a strict dehydrogenation process. In addition, some hydrogen embrittlement does not manifest as delayed fracture. For example, electroplating fixtures (steel wire, copper wire) have serious hydrogen infiltration due to repeated electroplating and pickling and stripping, which often occurs when they are in use. The phenomenon of brittle fracture; the mandrel used for shotgun precision forging, after being chrome-plated for many times, fell to the ground and fractured; some quenched parts (with large internal stress) cracked during pickling. These parts are seriously permeated by hydrogen, and cracks occur without external stress, and the original toughness can no longer be restored by removing the shaft pins.

When the shaft pin is designed for anti-reduction of the shaft pin, the friction type connection of the shaft pin is that the external shear force reaches the maximum possible friction force provided by the bolt tightening force between the contact surfaces of the plates as the limit state, that is, the connection is guaranteed during the entire use period. The internal and external shear forces do not exceed the maximum frictional force. The plate will not undergo relative slip deformation (the original gap between the screw and the hole wall is always maintained), and the connected plate will be elastically stressed as a whole. In the design of shear resistance, the external shear force is allowed to exceed the maximum friction force in the high-strength shaft pin pressure-bearing connection. At this time, relative slip deformation occurs between the connected plates until the bolt rod contacts the hole wall, and then the connection is made by bolts. The shearing of the shaft and the bearing of the hole wall and the friction between the contact surfaces of the plates jointly transmit the force, and finally the shearing of the shaft or the bearing of the hole wall is regarded as the limit state of the connection shearing.