INVESTIGATION OF THE BEARING UNIT FOR PISTON HEAD OF CONNECTING ROD

Abstract

The article investigates the bearing unit of the piston head of the connecting rod (PGSh) of 6DN 12/2x12 type diesel transport. The PGSh bearing assembly contains a two-row, non-standard needle bearing of a non-standard design. Needle bearings in the PGSh assembly are often used for the designs of high-speed small-sized two-stroke internal combustion engines. Bearing failures PGS appear as a result of wear of the working surfaces at significant speeds of rotation of the crankshaft and low loads. In order to increase durability, the production technology of its parts is improved, the quality of installation is improved and the heat sink is provided. A design, a complete analysis of the geometry and materials of which the basic elements are made is given. Distinctive features of the design are the installation of the sleeve in PGSh with a gap that provides the necessary mobility relative to the connecting rod, and rotation of the piston pin in working condition in the piston bosses. The operating temperatures of the loaded part of the raceway surface are provided only by a sufficient supply of lubricant. To lubricate the raceways and needle rollers in the bearing bush there are four radial holes. To increase productivity and reduce the cost of rounding off the sharp edges of the holes along the outer and inner surface of the sleeve, it is proposed to perform this procedure using the electrochemical method. To compare the fatigue strength of the sleeves manufactured by serial technology (manually) and using the method of electro-chemical processing, their accelerated durability tests were carried out, the results were analyzed. In the process of research, a design scheme for loading the sleeve was developed. For this purpose, a special device for fatigue tests has been manufactured. A mathematical model was compiled and the optimal choice of modes was analyzed. Studies have been carried out that make it possible to draw practically important conclusions about the fatigue strength in bending of experimental and serial bushings. It has been established that the electrochemical technology of processing the edges of the holes does not reduce the fatigue strength of steel ShKh15-Sh.