PSI - Issue 40

Aleksey Antimonov et al. / Procedia Structural Integrity 40 (2022) 17–26 Aleksey Antimonov, Nadezhda Pushkareva / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction Thick-walled steel pipes of small diameter are used in the fuel equipment of diesel engines. The basis of this pipes production technology is coiled drawing on a self-aligning mandrel in several passes. To implement this process, the end of the pipe is compressed along the diameter, i.e. sharpened, then it is run in a die, grasped with pincers of a drawing mill and pulled. In the next step the pointed end of the pipe is cut off. Grease is applied into the pipe and a mandrel is inserted. The pipe end is compressed again and the drawing process is repeated. Cutting of rolled products and pipes is carried out by different methods by Veselovskij (1973), Poljanskij et al. (1985) and Bondarenko (1968). Blade tools - band and circular saws are widely used according to Kubrin and Medvedjuk (1966). The use of this tool in this case is limited by its high cost, low tool life and low productivity of cutting process. To restore the cutting ability, regrinding with the use of special equipment is required. The advantage of the process of cutting steel with an abrasive tool is high productivity according to Ural.fil. VNII abrazivov i shlifovanija (1988). Bakelite-bound abrasive wheels are cheap, but the consumption due to the tool wear is quite large, which ultimately equals its price with the bladed tool. The disadvantage is the high temperature in the cutting area, especially while cutting pipes. The jet of hot abrasive grains and molten metal gets inside the pipe. This causes the abrasive to weld to the inner surface. This requires subsequent cleaning of the workpieces. In addition, cutting with bladed and abrasive tools generates waste in the form of chips and abrasives that must be disposed off. Non-waste methods include shear and bend breaking of round bars, the use of which ensures high productivity by Finkel' et al. (1982) and Filimonov (2003). In this case a cheap tool of a simple design, resistant to destruction and deterioration, is used. At the same time shear and bend breaking leads to cross- section defects, which doesn’t allow using these methods for pipe breaking. Laser, plasma and waterjet cutting ways are used to process materials in complex technological processes on numerically controlled machines and are not intended for cutting bars and pipes into workpieces according to Golubev and Lebedev (1988), Shirshov and Kotikov (1987), Poljanskij and Nesterov (2004). 2. Purpose of the work Development and research of high-performance process and equipment for cutting pipes without the use of abrasive and bladed cutting tools. Studying the possibility of replacing the cutting process by brittle cutting based on the fatigue fracture effect. 3. Problem statement Materials fatigue is the cause of machine parts and structural elements destruction by Terent'ev and Korableva (2015). Under the action of cyclic loads, a fatigue crack appears in the material, with the development of which the cross-sectional area of the part gradually decreases and the stress in it increases. When the stress reaches the fatigue limit, the part suddenly fails. The fatigue limit depends on material properties, presence of a stress concentrator and surface roughness. The paper proposes the use of the fatigue fracture effect for round bars and pipes with the study of the process productivity.