Antifrictional Characteristics of Sliding Bearings from Modified Pressed Wood
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frictional Characteristics of Sliding Bearings from Modified Pressed Wood M. V. Anikeyevaa, * and V. I. Vrublevskayaa aBelarusian
State University of Transport, Gomel, 246653 Belarus *e-mail: [email protected]
Received December 9, 2019; revised July 2, 2020; accepted July 7, 2020
Abstract—In this study, we experimentally tested slide bearings made of modified pressed wood (MPW), showing that a high probability of their failure occurs when the counterbody surface hardness is less than 50 HRC. For the first time, laboratory tests of antifriction properties of MPW bushings with counterbodies having various hardness of the contact surface were performed in order to predict the operating modes of friction units of machines and mechanisms. In experiments according to the “shaft–partial insert” scheme on a 2070 SMT-1 friction machine, 45, 45Kh, and 18KhGT-steel rollers were used as a counterbody. The hardened steel rollers were tempered to low, medium, and high temperatures in order to obtain various hardness of the contact surface. The pressed wood inserts were impregnated with MC-20 mineral aviation oil thickened with a high-molecular additive. Keywords: modified pressed wood, sliding bearings, bushings, counterbody, heat treatment of counterbody, tribotechnical tests, friction coefficient, wear rate DOI: 10.3103/S1068366620050025
INTRODUCTION High quality wear-resistant self-lubricating sliding bearings were developed based on theoretical and experimental data and their analysis. The technological foundations for the production of pressed wood sliding bearings were developed. The choice of birch wood (high-strength natural composite) was justified because its microscopic structure is similar to the hardest wood on the planet, lignum vitae. A method of end-press deformation of a wood card into a bushing and semiautomatic devices for the production of sliding bearings have been invented. The choice of lubricants for modifying wood bushings (liners) was substantiated and the design and manufacturing technology of self-aligning sliding bearings was developed. Extensive industrial tests of self-lubricating sliding bearings (SSBs) were carried out [1–6]. However, during SSB operation in abrasive-aggressive environments, cases of their failure were revealed due to poorquality heat treatment of the counterbody. The experience of installing SSBs in the seed drill coulters instead of rolling bearings showed high operational ability of the friction unit in abrasive-aggressive environments. However, after 24 h of operation, performance loss of a batch of bearings was recorded. When disassembling a defective unit, catastrophic wear of the metal surfaces of counterbodies was
revealed. The hardness of the counterbody surface was found to be in the range of 23–27 HRC, which indicates a discrepancy from the permissible value according to the design documentation, which should be 45– 55 HRC. Therefore, there is a need to comply with the heat treatment modes of the counterbody surface and to study the optimal values of its hard
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