An Electrothermal Model Based Adaptive Control of Resistance Spot Welding Process

Ziyad Kas^*, Manohar Das

Department of Electrical and Computer Engineering, Oakland University, Rochester, USA.

DOI: 10.4236/ica.2015.62014                

Abstract

Resistance Spot Welding (RSW) is a process commonly used for joining a stack of two or three metal sheets at desired spots. The weld is accomplished by holding the metallic workpieces together by applying pressure through the tips of a pair of electrodes and then passing a strong electric current for a short duration. Inconsistent weld and insufficient nugget size are some of the common problems associated with RSW. To overcome these problems, a new adaptive control scheme is proposed in this paper. It is based on an electrothermal dynamical model of the RSW process, and utilizes the principle of adaptive one-step-ahead control. It is basically a tracking controller that adjusts the weld current continuously to make sure that the temperature of the workpieces or the weld nugget tracks a desired reference temperature profile. The proposed control scheme is expected to reduce energy consumption by 5% or more per weld, which can result in significant energy savings for any application requiring a high volume of spot welds. The design steps are discussed in details. Also, results of some simulation studies are presented.

Keywords

Resistance Spot Welding, Adaptive Control, Nugget Formation, Energy Saving

Conflicts of Interest

The authors declare no conflicts of interest.

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