Method of and apparatus for joining plate members by the use of anchor pegs

A welding apparatus for joining a first electroconductive plate member to a second electroconductive plate member, said first and second plate members being prepared from respective metals dissimilar from each other, by the use of at least one anchor peg made of the same metal as the second plate member, said apparatus comprising:

• first and second welding electrodes supported for movement close to and away from each other, said first welding electrodes having a peg seat defined therein for receiving the anchor peg therein;
• a drive means for driving the first and second welding electrodes to move close to each other with the first and second plate members sandwiched between the second welding electrode and the anchor peg received in the first welding electrode;
• a power supply control means for applying an electric current of a controlled magnitude for a controlled duration to the first and second welding electrodes to initially cause a portion of the first plate member held in contact with the anchor peg to melt by resistance-heating of the anchor peg to thereby allow the anchor peg to be pierced through the first plate member and then to cause the anchor peg extending completely across a thickness of the first plate member to be welded to the second plate member.