Detection and Measurement of Defects in Butt Welds

Abstract

Sheet metal is produced in rolling mills in the form of coils of finite length. However, stamping and forming plants use these coils as a continuous stream of material to produce all the products we take for granted throughout society. Thus, the middle of this production chain must contain a “shock absorber” where the end of one coil is welded to the beginning of another. If this weld fails, expensive damage can result and productivity is definitely slowed down. Figure 1 shows this process in a schematic form and indicates that the welding is performed in between two clamps that hold the ends of the coils together while the weld is made. Special storage sections are included in the line so that the downstream flow of metal is not interrupted during the time in which the upstream flow is stopped for the weld. This welding machine not only forms the joint but knives clean off the weld bead on the top and bottom of the plate so that a smooth surface is presented to the downstream machines.