The disclosed clamp device for clamping blank pieces may comprise a mounting table, first and second clamping units, positioning units, and lock units. The mounting table is for placing thereon first and second blank pieces. The first and second clamping units have respective clamp plates that are able to be put on the first and second blank pieces while permitting a guided movement of the first and second blank pieces on the mounting table. The positioning units move the first and second blank pieces to establish a positioning of the first and second blank pieces on the mounting table. The lock units apply a given force to the first and second clamp plates to lock the first and second blank pieces.