Control of wire tip deflection in a consumable electrode type arc welding torch

Abstract

Summary The fundamental requirements for torch construction have been clarified as follows: to provide the specified curvature for a wire and to be able to control its rotation at the same time, so that the accuracy can be improved when aiming at a target position in a welded joint. In order to provide a set curvature for the wire of 1.2 mm diameter, it is necessary to provide the torch with both a radius of curvature of 90 mm or less and a curve with a bend angle of 75° or larger. When the wrist (namely the secondary, axis) of a robot is twisted, it is difficult to restrict the rotation of the wire inside the torch only by selecting both a simple curvature and a bend angle for the curved torch. The rotation of the wire tip can be restricted by providing a wire path with two curves whose centres of curvature are in opposite positions to each other. By using a wire reforming type torch such as the above, even when the bend direction of the curvature of the wire supplied changes and/or when a twisted wire is fed, the deflection of the wire tip from the datum of the torch can extensively be restricted and controlled to aim at the target position in joints. Furthermore, even if the wire conduit connected to the torch vibrates, the deflection of the wire tip position is within about 0.1 mm and the stability of both the welding current and the voltage can be maintained until the end of the life of a contact tube.