FREIGHT AND PASSENGER VEHICLES PARTS RECONDITIONING TECHNIQUE

Abstract

High accuracy and efficiency indices of machining of worn-out after continuous service parts, reconditioned using materials with high physical and mechanical properties have been studied; a reconditioning technique for worn-out surfaces of parts have been presented; to restore the dimensions of some parts, thermal spraying technique without inadmissible excessive heating of the parts has been chosen, and for another group of parts the process of manual argon-arc surfacing has been chosen; some specifications of the parts of the tram, trackless trolley bus, "KAMAZ", DT-75 tractor reconditioned by means of surfacing, coating and machining are given. Theoretical analysis of the conditions of the reduction of the elastic displacement value, appearing in a technological system during mechanical processing and determining the parameters of machining precision has been performed. Machining accuracy and efficiency improving features for grinding and cutting with cutting tools of parts with hardened (wear-resistant hardfacing materials with hardness up to HRC 63) function surfaces have been theoretically substantiated; some regularities of stock removal while grinding parts reconditioned using wear-resistant hardfacing materials have been analytically described, ways to improve the efficiency of their machining involving application of the method of deep grinding with the wheel periphery with rather low parts speed have been defined. Some ways to increase machining efficiency, to reduce energy consumption of machining and thickness of the cutting by grains of the wheel, and thus the wheel wear rate are presented. By means of calculations it was found out that realizing deep grinding of facing material, machining efficiency can increase by up to 8 times (with the same cutting thickness by a wheel grain) compared with the deep grinding of a solid (homogenous) material. Significant potential for grinding parts restored using wear-resistant surfacing materials, which opens new prospects for machining of resurfaced and face-hardened parts for freight and passenger vehicles, is shown. Potential for machining efficiency enhancement of the mentioned parts with cutting tools made of superhard synthetic materials, hard alloys with wear-resistant coatings, the use of damping cutters, and diamond-abrasive grinding is specified.