FEM Simulation of Gas and Plasma Cutting with Emphasis on Precision of Cutting

概要

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To achieve truly effective automation or mechanization of the ship structure assembling line, it is necessary to maintain much higher precision in each manufacturing stage, such as cutting and welding, compared to that required for the system depending on skills of workers. Since the flame cutting is the first stage of the assembly and it determines large part of the accuracy problems, controlling the precision in the flame cutting is receiving more attention now. Although it has long been considered that residual plastic strain and the motion of the plate due to the transient thermal deformation are the main causes of the cutting error, hardly any studies have been conducted to investigate these factors theoretically and quantitatively. In this paper a computational method for simulating the cutting process, based on the thermal-elastic-plastic FEM, has been developed. The proposed method is verified by comparing the computations with the experimental results obtained for the plasma cutting.Using the FEM model, the residual plastic strain and the plate motion due to the transient thermal expansion are obtained respectively. Their effects are quantitatively discussed. The results show that these factors have great influences on the one-side cutting and small effects on the two-side simultaneous cutting. The influences of the residual stress existing in the plate before cutting are also investigated.
社団法人日本船舶海洋工学会の論文