PURPOSE: To facilitate manufacture of interchangeable parts and to shorten time for changing parts at the time of wear, and to improve the efficiency of work by making Z bar that guides a cylindrical blank to a set of two blocks having opposing L-shaped faces.

CONSTITUTION: In manufacturing process of a can drum, a Z-bar 4 that guides the cylindrical blank 1 of a welded can to welding process is made to a set of two blocks 9, 10 constituting opposing L-shaped faces, and grooves 6', 8' are formed in the lower side. When guiding two end faces 2, 3 of the cylindrical block 1, this is brought into contact with bottom faces 5, 7 of the Z-bar 4 and slid, and both sides of the blank inside of the edge of the blank 1 are guided by the faces of blocks 9, 10. As only heavily worn tip part is constituted of blocks 9, 10, and screwed to the body of the Z-bar 4 with a stud bolt 13, only worn block 9 or 10 can be replaced easily.