Method for welding coated steel plate

摘要

Provided is a method for welding coated steel plates in which a metal portion of a metal plate having one surface coated with an insulating film is punched from the other surface having no insulating film with a punch having a flat end and a die paired therewith, whereby the lower end of the metal portion on the inner surface of the punched hole is exposed at the surface coated with the insulating film. The exposed portion is then brought into contact with another metal plate, allowing an electric current to pass therethrough for jointing by resistance welding.