Changing the Stress-strain State of the Working Surface of a Part with an Antifriction Coating

The article deals with the issue of increasing the durability of the camshaft of an internal combustion engine by improving the operational properties of cams. It is determined that by studying the stress-strain state of individual elements of a part, it is possible to solve a number of technological problems. Taking into account that in most cases the destruction of a part begins from its surface, the stress-strain state of the surface layer has a significant impact on the operational properties of parts. The study of the parameters of the stress-strain state on the working surface of the cam of the camshaft of an internal combustion engine was carried out by modelling using the finite element method. The model takes into account the design features of the camshaft, the operating conditions of the cam-pusher connection, and the forces acting in the gas distribution mechanism at the moment of valve opening. To adequately reproduce the loads in the details of the studied assembly, a finite element model of the camshaft was created, with the camshaft journals in contact with the bushings and the cams in contact with one of the pushrods. The calculation results confirmed that it is in the cam-pusher contact zone that the maximum stress values are observed. To determine the ways to improve the operational properties of the working surfaces of cams, the parameters of the stress-strain state of the base cam and the cam with an antifriction coating applied by finishing antifriction non-abrasive treatment were investigated. It was found that the maximum stress is about 60 MPa for the uncoated cam and about 37 MPa for the cams with antifriction coatings. In addition, a change in the shape of the diagram was recorded: in the cams with antifriction coatings, the stresses are more evenly applied in the contact patch. The improvement in the stress state of the cams can be explained by the presence of an antifriction coating, which reduces not only the friction coefficient but also serves as a solid lubricant. The obtained regularities allow us to assert the expediency of finishing antifriction non-abrasive treatment of cams when solving the issue of increasing the durability of the camshaft.