Restoration of bronze bushes by the method of surface plastic deformation

Abstract

The restoration cost for agricultural machinery parts systematically influences on that of agricultural production. Hence the need to find the most effective and less expensive methods for repairing these parts. The bushes of the connecting rods of internal combustion engines are among the parts that wear out quickly and are made with expensive and deficient bronzes. The technical equipment used consists a worn out bushes of bronze treated by various methods, a vibro-rolling device, deformation software, a profilograph-profilometer, a microscope, and a machine of friction. In order to analyze the performance of the bushes of the connecting rods of internal combustion engines resulting from various treatments, the following parameters were determined: the height of the micro-relief elements, the absorption and the surface oil retention force, the optimum support surface, the wear and the wear intensity, the temperature of the friction area and the duration of the running-in period. The vibro-rolling followed by the deformation by broaching increases oil retention force from 1.8 to 2 times, and the wear resistance from 1.86 to 3.45 times as compared with the traditional technology. This new technology can be used for the restoration of the bushes of the connecting rods of internal combustion engines.

Designing the structures of discrete solid­alloy elements for broaching the holes of significant diameter based on the assessment of their strength

“…The calculation was carried out under unit normal load σ n =1 MPa. To use the obtained results under other loads, it is necessary to use dependence (4), derived from the condition of the elastic problem linearity, and the strength conditions of the elements of the prefabricated tool, which are expressed by dependence (5). The value of the permissible contact pressure is estimated by dependence (7).…”

“…Then, from (4), taking into consideration (5) and 6, we obtain σ n =3,566 MPa ≈3.6 GPa. This is the permissible contact pressure on the tool.…”

“…UDC 531.374; 539.213 DOI: 10.15587/1729-4061.2020.203524 deformation strengthening. Currently, DBR is applied in engineering production when machining precise holes with low roughness and for draft operations to adjust pipe blanks made from various materials before further treatment [3][4][5]. In this case, both small surface and large deformations can be executed, reaching 20 %, which change the size of a component and the mechanical characteristics of the machined material [6].…”

“…The strength condition for a solid-alloy insert takes the following form: ( 6 ) n is the strength margin factor. Then, from (4), taking into consideration (5) and 6, we obtain a dependence to determine the acceptable contact load:…”

Methodology of technological design in the restoration of parts

“…Operation as a stage in a part life cycle is terminated after reaching the maximum allowable wear, leading to the cessation of the entire mechanism operation. To extend the life cycle of worn parts, technologies for their restoration are used [3]. These technologies are fundamentally different from the technologies for manufacturing a new part, although the end product of production in both cases is the same finished part with its own service functions.…”