Patent ID: 7091447

Claim:
A local heatsink welding device for improving mechanical properties of welds of a base metal, comprising: a welding torch disposed above welds of two pieces of the base metal placed in contact with each other to be welded, the welding torch welding the pieces of the base metal by melting a welding wire or an electrode on the welds of the base metal and fusing the pieces together; and a cooling unit disposed to be able to spray a low-temperature fluid from the sides of the welding torch, the cooling unit cooling at least a portion of a non-transformation heat-affected zone formed around the outside of a fusion zone in which the base metal is molten during welding; wherein the cooling unit comprises a pair of spray nozzles disposed at both sides of the welding torch to be able to move up and down, the nozzles spraying the low-temperature fluid onto the heat-affected zone, a fluid supply unit that supplies the low-temperature fluid to the spray nozzles, a pair of fluid supply hoses connected between the spray nozzles and the fluid supply unit, the fluid supply hoses forming the flow path through which the fluid from the fluid supply unit moves to the spray nozzles, and a spray nozzle control device controlling locations of the spray nozzles up and down and left and right with respect to the base metal; and wherein a shielding curtain is disposed between each of the spray nozzles and the welding torch to prevent the low-temperature fluid discharged from the spray nozzle from flowing to the fusion zone from the heat-affected zone.