Joint formed by punch

Assembly Automation

ISSN: 0144-5154

Article publication date: 1 June 2000




(2000), "Joint formed by punch", Assembly Automation, Vol. 20 No. 2.



Emerald Group Publishing Limited

Copyright © 2000, MCB UP Limited

Joint formed by punch

Joint formed by punch

Keywords: Assembly, Joining

Applicant: BTM Corp. (US)Patent number US5984563Publication date: 16 November 1999Title: Apparatus for joining sheet material and joint formed therein

Conventional leakproof joints have seen tremendous commercial success for use in applications such as microwave ovens and aluminium automobile bodies. They consist of two or more sheets of material having a button or joint formed by a uniformly cylindrical punch forcibly pushing a punch side sheet of material into interlocking engagement with a die side sheet of material. In the present invention, an improved apparatus for joining sheet material provides a stepped punch. This serves to strengthen a joint between two or more sheets of material by creating a stepped segment in at least one of these sheets of material. During formation of this stepped segment, material is forcibly displaced toward another segment of material that is outwardly expanded to interlock with the adjacent sheet of material. The punch and joint achieve a surprisingly stronger leakproof joint. Furthermore, the joint has improved wall thickness that is more resistant to fracture as compared with conventional leakproof joints. The punch, joint and method thus reduce scrap during the joint forming process.

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