METHOD AND DEVICE FOR PUNCHING HOLES IN DOUBLE-WALLED MATERIALS

摘要

It is described a method of making holes in a first plate (1) and in a second plate (2) situated at a distance from the first plate (1). The method comprises the steps of punching a hole (h1) in the first plate (1) by means of a punch nipple (5); punching a concentric part (CP) which includes the hole out of the first plate (1); punching a hole (h2) in the second plate (2) by means of the punch nipple (5); and pushing the punched out concentric part (CP) onto the hole (h2) into the second plate (2). This results in increased strength and stress characteristics especially around the hole (h2) in the second plate (2), which in turn may result in material savings, especially if the method is applied to a hollow rim of a wheel which is to be provided with spokes by means of spoke nipples attached to the rim.