Patent ID: 8003914

Claim:
A butt welding system of steel plate in which steel plates are welded at a butting portion for jointing, the system comprising: gripping means for gripping the steel plates to be jointed together near butting portions of the steel plates; butting means for butting the steel plates gripped by the gripping means at the butting portions, and for applying a predetermined butting load to the butting portion of the butted steel plates; matching means for relatively moving the steel plates butted by the butting means so as to match-slide the butting portions of the steel plates; and welding means for welding the butting portion of the steel plates along a welding line; wherein the gripping means includes a base that extends along the welding line and supports portions of lower surfaces of the steel plates near the butting portions; a clamp bar provided above the base so as to face the base; a plurality of clampers vertically disposed on the clamp bar so as to be vertically movable and arranged along the clamp bar; a plurality of compression springs interposed between the clamp bar and each clamper and disposed in parallel for each damper; and clamp-bar driving means for driving the clamp bar in a vertical direction; and wherein spring force of one or more of the compression springs disposed closer to an end of each clamper is set larger than that of one or more of the compression springs disposed closer to a center.