Automatic welding machine

An automatic welding machine comprising a link actuation device,

• the link actuation device including:
• a proximal end side link hub;
• a distal end side link hub;
• and
• three or more link mechanisms which each couple the distal end side link hub to the proximal end side link hub such that a posture of the distal end side link hub can be changed relative to the proximal end side link hub, wherein
• each of the link mechanisms includes:
• a proximal side end link member having one end rotatably coupled to the proximal end side link hub;
• a distal side end link member having one end rotatably coupled to the distal end side link hub;
• and
• an intermediate link member having opposite ends rotatably coupled to other ends of the proximal side end link member and the distal side end link member, respectively,
• each of the link mechanisms has such a shape that a geometric model of the link mechanism represented by straight lines shows symmetry between a proximal end side portion thereof and a distal end side portion thereof with respect to a center portion of the intermediate link member, and
• two or more link mechanisms among the three or more link mechanisms are each provided with a posture changing actuator which arbitrarily changes the posture of the distal end side link hub relative to the proximal end side link hub,
• the link actuation device being disposed on a mount while the proximal end side link hub is directly or indirectly fixed to the mount,
• a welding torch being mounted to the distal end side link hub, and
• the link actuation device being provided with both or either one of a one-or-more-axes linear motion actuator which causes the link actuation device to advance and retract relative to the mount, and a one-or-more-axes linear motion actuator which causes a workpiece to advance and retract relative to the mount, the workpiece serving as a target to be subjected to welding work performed by the welding torch.