Three-dimensional numerical study of heat-affected zone in induction welding of tubes

Purpose Quality of the weld joint produced by high-frequency induction (HFI) welding of steel tubes is attributed to a number of process parameters. There are several important process parameters such as the speed of the welding line, the angle of the approaching strip edges, the physical configuration of the induction coil, impeder, formed steel strip and weld rolls with respect to each other, the pressure of the weld rolls and frequency of the high-frequency current in the induction coil. The purpose of this paper is to develop a 3D model of tube welding process that incorporates realistic material properties and movement of the strip. Design/methodology/approach 3D numerical simulation by the finite element method (FEM) can be used to understand the influence of these process parameters. In this study, the authors have developed a quasi-steady model along with the coupling of electromagnetic and thermal model and incorporation of non-linear electromagnetic and thermal material properties. Findings In this study, 3D FEM model has been established which gives results in accordance with previously published work on induction tube welding. The effect of the Vee-angle and frequency on the temperature profile created in the strip edge during the electromagnetic heating is studied. Practical implications The authors are now able to simulate the induction tube welding process at a more reasonable computational cost enabling an analysis of the process. Originality/value A 3D model has been developed for induction tube welding. A non-linearly coupled system of Maxwell’s electromagnetic equation and the heat equation is implemented using the fixed point iteration method. The model also takes into account non-linear magnetic and thermal material properties. Adaptive remeshing is implemented to optimise mesh size for the electrical skin depth of induced current in the strip. The model also accounts for the high welding-line speeds which influence the mode of heat transfer in the strip.

Improving induction tube welding system performance using soft magnetic composites

Purpose This paper aims to demonstrate the benefits of using different impeder materials for induction tube welding systems. Design/methodology/approach To show the difference in using various impeder materials, a new approach was taken to model tube welding systems in two and three dimensions. Three-dimensional (3-D) electromagnetic models were used to determine the current distribution along the weld vee as well as the permeability of the tube along the length of the welding system. Two-dimensional (2-D) coupled electromagnetic plus thermal models with rotational movement were used to determine the temperature distribution in the heat-affected zone. Findings Simulation results suggest upwards of 25 per cent system power savings when using a soft magnetic composite (SMC) impeder rather than the traditional ferrites. Research limitations/implications There is currently a lack of experimental data to validate the models, but future work will include comparison of models to real-world trials. Practical implications When dealing with tube welding systems, there are possibilities to improve process efficiency or increase production quality and output by improving the impeder material. Originality/value While simulations of tube welding systems have been done previously, studies on improving impeder materials are rarely carried out. This paper brings to light possible improvements to be made to induction tube welding systems.

Improving Inductive Welding System Performance with Soft Magnetic Composites

Inductive welding is a popular method for making metallic tubes used in a variety of industries. A majority of these induction tube welding systems use internal magnetic flux controllers (impeders) to limit the current flowing on the ID of the tube under the induction coil. As higher power, solid state IGBT power supplies become more widely available for tube welding, and demand for lower cost tubes with higher strength to weight ratios increases, magnetic loading of these impeders is also increasing. Traditionally, impeders are made of ferrites which have a low saturation flux density and can become saturated in these demanding conditions. Saturation of the impeder results in greater currents on the tube ID and lower process efficiency and weld quality. In order to expand the upper operating range of these more demanding systems while maintaining the weld quality, a change in impeder material from ferrites to soft magnetic composites (SMC) with greater saturation flux densities is suggested, as well as the addition of external magnetic controllers (bridges). In this paper, a comparison is made between induction systems with impeders constructed from traditional ferrites and those utilizing bridges and impeders made from SMCs. To do this, a simulation study will be used to estimate impeder flux density, required coil current, and temperature distribution at the end of heating when using impeders made of the two materials, with and without bridges. By soft coupling 3-D electromagnetic models with 2-D electromagnetic and thermal models, a fast and accurate depiction of the welding process can be achieved. A case study is presented comparing simulation results to experimental results.

Numerical Simulation and Investigation of High Frequency Tube Welding Process

Welding processes and installations used nowadays are mainly developed on practical experience and analytical calculations. Nevertheless, high frequency induction tube welding is a very complex three-dimensional dynamic process, where the electromagnetic and thermal characteristics are distributed not only in space but in time as well. A more profound detailed investigation of the induction tube welding process can be only done by numerical modeling. Full and local three-dimensional transient numerical models of induction tube welding process with continuous movement of the welded tube have been developed and tested. Coupled electromagnetic and thermal analyses are carried out at each time step of simulation for correction of temperature dependent material properties. Voltage or current of the induction coil can be individually input into electromagnetic analysis at each time step. This approach allows simulating “quasi” steady-state and transient operation modes.

Ultrasonic TOFD in the Application of Thick Wall Tube Welding Seam Detection Pre-Research

This article firstly introduces the ultrasonic TOFD (Time-of-flight - Diffraction) detection technology of detection principle, advantages and disadvantages, and then summarizes the ultrasonic TOFD technique related testing standard, finally combining the reality of tube mill, analyses the pipe material testing near the surface of the blind area and radian impact problems, discusses the ultrasonic TOFD in application prospect in the field of thick wall tube welding seam detection.

Simulation Analysis on the Contact Status during Sheet-to-Tube Single Sided Spot Welding Process

Single sided resistance spot welding (SSRSW) developed from RSW is a feasible plan to join vehicle structure to closed-form tube and is increasingly used in automobile manufacturing. During the process of SSSW, large deformation and complex contact status of the workpieces occur because there is no inside support. The complex contact status has directly influence on the size of the nugget which is critical to the quality of welding. In this study, the contact statuses during the current stage of sheet-to-tube spot welding were researched by numerical method. It was found that the widths of the contact regions of electrode to sheet and sheet and sheet to tube have dynamic change during welding process which decided the size and speed of the nugget formation. The results have direct guiding significance to the study on ring nugget formation during sheet-to-tube welding.

Application of Flexible Combine-Clamp in Digital Rapid Production for Aircraft Tube

Aiming at the existing problem of plane tube welding jig manufacturing, many systems developed such as standard components parameterized modeling system, computer intelligent reasoning system, standard components replacement system, accuracy checking system and standard components management system, and also replace the traditional standard samples by three-dimensional model of tube, then realize the digital rapid design and manufacture of combined welding jig.