| 摘要 |
There is disclosed an improved apparatus for joining a plurality of pieces of sheet metal or other sheet material items by first drawing and then laterally extruding portions of the material to be joined into an enlarged shape which will permanently mechanically interlock the sheet material pieces. The apparatus utilizes a novel die construction in which portions thereof are resiliently biased toward one another and pivot or slide laterally in response to lateral extrusion of the joining material, and which is applicable to conventional "lanced" type joints as well as to a novel leakproof joint. A method of forming a leakproof joint between a plurality of pieces of sheet material and a method of fabricating a novel die construction are also disclosed.
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