Mechanochemical Fracture of the Components of Wood-Cutting Equipment
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MECHANOCHEMICAL FRACTURE OF THE COMPONENTS OF WOOD-CUTTING EQUIPMENT Е. А. Pamfilov,1, 2 S. V. Lukashov,1 and Ya. S. Prozorov1 We study the operating conditions, mechanisms, and regularities of wear of the surfaces of the friction units of chippers. We recorded a complex set of phenomena in the friction zone of the cutter shaft (or the cutting drum) and wood, which reveals the predominance of the corrosion-mechanical type of wear. It is shown that water, carboxylic acids, and polyphenol compounds most strongly affect the character of wear and wear rate. The mechanical component of wear in friction against wood is caused by the entrainment of dispersed wear particles in the contact zone, the appearance of abrasive particles (earth, sand, and clay) together with machined wood, or the penetration of these particles in the junctions of the chipper from the outer medium. The influence of hydrogenation of the surface on the wear resistance of the material of the components of woodworking machinery is established. We analyze the regularities and mechanisms of wear of the components of the friction units of chippers, formulate the requirements to the choice of the method of improvement the wear resistance, and theoretically justify the structural-phase composition and the physicochemical properties of the surface layer of the analyzed components. Keywords: friction units, wood, carboxylic acids, polyphenol compounds, hydrogenation, wear resistance.
The engineering and economic parameters of manufacturing of numerous wooden composite materials (consumption of wood raw materials and binders, energy consumption, and the quality of manufactured products) are formed already in the stage of manufacturing of the main component of the composite, i.e., of wood chips. For this purpose, it is customary to use chippers of various types, the loss of the serviceability of which is mainly connected with the wear of the working surfaces of the components of friction units, namely, of the cutter shaft, cutting drum, knife holders, etc. For this reason, the problem of choosing wear-resistant materials and efficient technologies of hardening of the wearing surfaces of the components of the friction units of equipment used for the production of wood chips seems to be quite urgent. To solve this problem, it is necessary to determine the principal factors affecting the wear processes and establish their regularities. The serviceability of the chippers is determined by the operating, design, and technological factors. Among the operating factors, we can mention the kinematic mode of operation, which includes the cutting and feed rates, the thickness of removed chips and its uniformity, the durations of the event of cutting and idle run, the direction of cutting relative to the annual layers, specific features of the formation of chip, and their removal from the cutting zone, the force factor, which includes the character of application of the load, forward force, the area of the contact zone, stress-strain state of units of the chipper, and the t
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