Patent ID: 9731476
Date: 2017-08-15
CPC Classifications: B21D,B32B,Y10T

Claim:
1. A composite metal sheet produced by joining at least two metal sheets together, comprising: projections formed in each of overlapping metal sheets; holes formed in each of the overlapping metal sheets; and a joint formed between the overlapping metal sheets and between each projection and each hole of each overlapping metal sheet, wherein the projections are formed by pressing and thus cutting the overlapping metal sheets along two cutting lines relative to a same uncut reference line such that each cutting line extends from and communicates with both terminals of the reference line, each projection having a portion whose width is wider than a length of the uncut reference line, each hole is formed by further pressing each cut projection relative to the uncut reference line and toward one of the overlapping metal sheets, the joint is formed between an outer peripheral cutting face of the projection of a first metal sheet and an inner peripheral cutting face of the hole of a second metal sheet due to friction between the portion of the outer peripheral face of the projection of the first metal sheet that is wider than the length of the uncut reference line, and the inner peripheral cutting face of the hole of the second metal sheet during the pressing, and due to the friction the outer peripheral cutting face of the projection of the first metal sheet and the inner peripheral cutting face of the hole of the second metal sheet are adhered to each other in the joint.