Automatic precision clinching system for manufacturing sheet metal tubes

A method for forming a finished clinched sheet metal tube from a sheet metal blank cut to size, said method comprising:

• a) moving said sheet metal blank to a position beneath a mandrel, wherein said mandrel has a first end connected to a fixed support and a second end connected to a movable support;
• b) lifting and holding said sheet metal blank to a bottom apex of said mandrel and wrapping said sheet metal blank around a bottom portion of said mandrel with a wrap strap;
• d) overlapping and holding opposing ends of said sheet metal blank across each other at a top portion of said mandrel using opposed side wipers;
• e) clinching said overlapping opposite ends of said sheet metal blank using clinching dies mounted in said mandrel and complementary clinching prongs to form clinched overlapping opposite ends, thereby forming said sheet metal tube;
• f) holding said clinched overlapping opposite ends of said sheet metal tube against the mandrel with a holding bar while withdrawing said clinching prongs;
• g) automatically removing said clinched tube from the mandrel after moving said holding bar and said clinching prongs a predetermined distance away from said mandrel, said removing step including the sub-steps of:
• (i) sliding said movable support away from said second end of said mandrel;
• (ii) moving said die bar away from said overlapping opposite ends of said clinched tube into said mandrel;
• and,
• (iii) moving a stripper plate along the length of said mandrel to move said clinched tube toward an extraction support bar extending from said second end of said mandrel.