Modifying Wood for Creation Plain Bearings of Timber Machines

Abstract

The use of modified wood in different friction pairs of timber machines and processing equipment is largely due to its high wear resistance, low coefficient of friction and good dissipative characteristics. The positive properties of composite materials are achieved by using technologies of volumetric modification and implantation of antifriction and heatconducting elements, as well as by forming a composite of crushed wood with the addition of modifying additives and three-dimensional reinforcement. The expansion of the scope of using composite materials in the designs of units with sliding friction pairs necessitates carrying out research on their performance and formation conditions for high level tribotechnical parameters: wear resistance, antifriction, heat resistance, etc. Lack of information on the effect from the factors providing the functional characteristics of wood-based materials including thermal conductivity and vibration absorption significantly complicates the problem analysis in design and technology when developing and producing bearing joints. Therefore, the purpose of this work was studying the conditions of contact interaction of plain bearings made of wood-metal composite materials, allowing for rheological effects, and developing the ways of control their tribotechnical parameters by changing the structure, composition and phase filler. Models of bearings of different types, which allow creating a regulated stress-strain state in sleeves and liners, were developed for these purposes. Research of the bearings performance made it possible to find vibration-damping properties when using suspended crushed fractions in the composite. Increased antifriction properties are achieved in the process of wood modification with electrolytic copper, while the manufacturability of a bearing sleeve is achieved when the support is formed directly at the installation site. Unlike most of the used antifriction materials, the bushings wood maintains the stability of structure in conditions of volumetric compression at negative and positive temperatures, and the wear processes occurring on the contact surfaces of wood-metal bearings are followed by the compaction of the sleeve material. The subsequent destruction is predominantly of fatigue nature, initiated by the dynamics of vibrations and disturbances of the system; therefore, an important part of further research is the assessment of the relaxation ability of wood-metal composites under shock-vibration loading with optimization of their composition according to this criterion.