Abstract: The present invention relates to a resistance welding method suitable for use in spot welding between a steel-base metal sheet, which has been plated for rust prevention purposes, and an aluminum-base metal sheet and aims to permit a current to flow at a high density across the plated steel sheet and the aluminum-clad steel sheet, thereby realizing high-quality welding.An aluminum-clad steel sheet comprised of a steel layer having projections and an aluminum layer is interposed between the plated steel sheet and the aluminum-base metal sheet to be welded to each other. An electrode is energized by a predetermined weld current from an alternating power supply. The current path is limited to the area of the projections, and metallic melt formed by melting of the plating is accommodated between the projections, preventing the current-carrying area from being increased.

Abstract: A method of producing a metal mold is disclosed. A heat resistant sheet is forcedly brought into close contact with a product configuration surface of a matrix such as a wooden pattern, a resin model, or the like by making use of negative pressure. The matrix is brought into contact with a melt of a low melting-point alloy while that state of close contact is being maintained and the melt is allowed to cool as it is, thereby casting one part of the mold which makes up a pair. The matrix is then removed, and by using the one part of the mold thus cast as a new matrix, this new matrix is brought into contact with the melt of a low melting-point alloy via the heat resistant rubber sheet and is allowed to cool as it is, thereby casting a counterpart of the mold that makes up the pair.