Patent GB-1357912-A (GB)
Title: Apparatus for moving wire
IPC: B23K9/29
Filed: 1971-05-19
Abstract: 1357912 Welding by fusion HOBART BROS CO 19 May 1971 [25 May 1970] 15890/71 Heading B3R In a consumable electrode wire feed device comprising a rotatable body having an electrode wire accommodating bore therethrough, and at least one freely rotatable roller mounted on said body with its axis inclined to the body axis and engageable with the electrode wire so as to impart movement of the wire through the body aperture in response to body rotation, the roller is carried on the body by way of a lever and a centrifugal weight is provided on the lever to at least counterbalance centrifugal force acting on the roller. The device is referred to in respect of feeding steel, aluminium or magnesium wire. The centrifugal weight may be such as to substan - tially balance the roller centrifugal force, in which case roller/wire contact force is effected by a biasing spring between a roller carrying lever and the body (Fig. 9, not shown) or between the roller and centrifugal weight ends of two opposed levers (Fig. 7, not shown), or by torsion rod mounting of levers (Figs. 17-21, not shown), such roller/wire contact force being independent of speed. The centrifugal weight may alternatively be such as to increase roller/wire contact with increasing body speed. When the device is used for only one diameter of wire, only one of a plurality of rollers need be lever mounted. As shown in Fig. 15, the rollers, preferably tungsten carbide surfaced, may have a profile A for easy wire insertion, B for wire deformation, or C for dual contacting. The feed devices may be provided at either end and/or at one or more intermediate positions of a feed cable. The feed devices closest to the wire source may be arranged to move the wire slower or faster than those remote from said source to put the wire respectively in tension or compression. Wire drive may be frictional only or, to-avoid slip, roller/ wire contact force may be such that the wire is deformed. The roller/wire contact force may be set to allow roller/wire slip with the body set to rotate at constant speed, or be set to effect roller/wire tracking, a constant torque device being provided so that the body rotates at different speeds. Where two sets of rollers are spaced along the wire line, the position of the second set is preferably such that at least one roller of said second set follows in one of the first set tracks. As shown, in a welding gun, two devices 35, 36 are rotated simultaneously by an hydraulic, pneumatic or electric motor 37, and each have two axially spaced pairs of diametrically opposed rollers. Provision is made for transmission through the gun of welding wire (through the devices 35, 36, the motor 37 and a contact tube 32), welding current, control current and shielding gas, the latter also cooling the motor and carrying away dirt or wire contamination from the devices 35, 36. In Figs. 25-28 (not shown), a feed device body carries two axially spaced groups of three co-operating rollers, each of pairs of rollers comprising one of each group being acted on by a corresponding single centrifugal weight and bias spring disposed transversely of the wire. The rollers of each group may contact the wire at coplanar points or at points outside a single plane. In Fig. 23 (not shown), wire twisting is prevented by using two axially spaced feed devices with opposite hand rollers, each device being driven in opposite rotational directions by a single motor through a bevel gear meshing two contra-rotating bevel gears. In Fig. 24 (not shown), accurate wire control, e.g. for arc spot welding, is provided by continuously rotating the wire feed devices and braking the wire, roller/wire slip resulting. The wire is braked by a solenoid brake controlled by a timer which is controlled automatically or by a trigger pulse.