Method and apparatus for producing welded metallic can body

An apparatus for producing a welded metallic can body from a metal blank bent into a cylindrical can-like structure with a marginal side edges overlapped, comprising:

• a pair of opposed parallel elongated electrodes, one of said parallel electrodes being divided into a plurality of portions positioned side-by-side in the direction of the length of said electrodes and electrically insulated from each other and individually movable toward and away from the opposed electrode;
• a pair of opposed parallel wire electrodes positioned on the opposed surfaces of said parallel electrodes for holding the overlapped edges of the can-like structure therebetween along the entire length of the structure;
• means connected to the respective electrode portions for providing currents from at least two separate sources of electric current and for passing electric currents electrically in parallel across said portions and the other electrode for a predetermined period of time and with the current through at least one of said portions being from one of said sources and being independent from the currents through the other portions and the currents having current values for causing the temperature rise in the overlapped edges of the can body-like structure to be uniform along the length of the overlapped edges;
• and means for exerting pressure on the respective electrode portions independently of the other electrode portions for pressing the wire electrodes and parallel electrodes against said overlapped edges with substantially uniform pressure along the entire length of said parallel electrodes.