Computer Aided Process Simulation for the Design and Manufacturing of High Quality Tube Mill Rolls and Practical Results of Simulation Data Application at HFI ERW Mill--Paper 1: Finite Element Simulation of the Roll Forming and HF Welding Process in the Production of Welded Tubes

摘要

The paper deals with the continuous Roll Forming (RF) and High-Frequency (HF) welding processes of Internal High-Pressure (IHP) tubes. Models of the RF process and the induction forced HF welding are presented using the Finite Element software program COPRA~R FEA RF with integrated MSC.MARC/Mentat~(TM) solver. In early works as a rule tubemaking was considered as an isothermal elastic-plastic deformation process. So it was impossible to investigate the influence of the temperature field on the tube's properties in the weld seam and in the heat affected zone. The HF welding has been considered separately without coupling to the forming process. In the so-called weld “V” the coil edges are heated by induction. Pressing the hot edges against each other some material is forged into the weld bulges. The weld bulges have to be cut off straight after the welding point. Without the consideration of these forging and cutting processes this material portion must be removed from the simulation models before the coil edges touch each other. In the paper a complete non-isothermal elastic-plastic numerical simulation method is presented including the roll forming process, the transient temperature fields during welding, the bulge cut-off, the temperature behaviour in cooling, and the tube calibration. The simulations are performed for 4 different roll geometries and 2 materials. The results are compared with real process measurements. Using numerical simulation the forming and welding process parameters are modified in order to improve the tubes' IHP properties by homogenization of the thickness and minimization of the total equivalent plastic strain (TEPS).