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Machine Welding - In machine welding, the operation is performed under the constant observation and control of a welding operator. The equipment mayor may not perform the loading and unloading of the work. The work may be stationary while a welding head is moved mechanically along the weld joint, or the work may be moved under a stationary welding head.
Machine welding can increase welding productivity by reducing operator fatigue and by increasing the consistency and quality of the welds. The equipment should control the following variables when welding:
1. Initiation and maintenance of the welding arc
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2. Feeding of the filler metal into the joint
3. Travel speed along the joint
In machine welding, the operator must be near to the point of welding to closely observe the operation and interact continuously with the equipment to assure proper placement and quality of the weld metal.
Machine welding devices generally fit into one of the following categories:
(a) Machine carriages
(b) Welding head manipulators
(c) Side-beam carriages
(d) Specialized welding machines
(e) Positioners, turntables, and turning rolls.
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These devices provide means for moving an automatic welding head relative to the part being welded or vice versa. Machine welding can be used with most fusion welding processes.
(a) Machine Carriages
A welding machine carriage provides relatively inexpensive means for providing arc motion. A typical carriage rides on a linear or curved track of the same contour as the joint to be welded.
Welding carriages may be employed for welding in the horizontal, vertical and overhead positions.
Tractor type carriages are used primarily for welding in the flat or horizontal position.
(b) Welding head manipulator
A welding head manipulator typically consists of a vertical mast and a horizontal boom that carries an automatic welding head. Manipulators usually have power for moving the boom up and down the mast, and in most units, the mast will swivel on the base.
Welding manipulators are used to position the welding head for longitudinal, transverse and circular welds.
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(c) Side-beam carriage
A side-beam carnage consists of a welding carriage mounted on a horizontal beam. It provides powered linear travel for the welding head. The powered welding carriage supports the welding head filler wire feeder, and sometimes, the operator controls. Typically, the welding head on the carriage is adjustable for vertical height and transverse position.
(d) Specialized welding machines
Special welding machines are available with custom clamping devices, torch travel mechanism, and other specific features. Applications include equipment for making circumferential and longitudinal welds on tanks and cylinders, welding piping and tubing, fabricating flanged beams, welding studs or bosses to plates, and for performing special maintenance work, such as the rebuilding of track pads for crawler type tractors.
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