Machine for welding thermoplastic sheets

A machine for separation and welding of sheets from a thermoplastic web comprising:

• a rotatable separation and welding means;
• an opposing roller having a cylindrical circumferential surface and an axis operative to oppose said separation and welding means;
• means for passing said thermoplastic web between said separation and welding means and said opposing roller;
• means for periodically contacting said separation and welding means to said web against said opposing roller and for welding and separating a leading portion of said web from the remainder thereof;
• means for conveying said leading portion away from said separation and welding means;
• said means for conveying including a conveying support;
• said conveying support defining a surface which intersects a surface of said opposing roller at a distance displaced from said welding gap in a direction toward said axis of said opposing roller;
• a guide plate tangentially adjoining said surface of said opposing roller for guiding said leading portion from said opposing roller to said conveyor surface;
• means for producing a high-speed flow of air through said welding gap, said flow of air being effective to hold said leading edge closely adjacent said circumferential surface of the opposing roller for a first distance and to permit said leading edge to separate from said circumferential surface at a second distance;
• and
• said guide plate being disposed beyond said second distance whereby said leading edge slides over said guide plate and is guided thereby to said conveying support.

A machine for welding seams in a thermoplastic web having at least two plies comprising:

• a separation and welding tool continuously rotating about an axis;
• a welding edge on said welding tool;
• an opposing roller having a cylindrical circumferential surface opposing said welding tool and defining a welding gap therebetween, said welding tool being effective to weld and separate said web into sheets each of which sheets includes a leading edge;
• first conveying means for feeding said thermoplastic web to said welding gap;
• second conveying means including means for removing said sheets from said welding gap;
• an elastically compressible strip rotating with said welding tool and located in a lagging direction relative to the rotation of said welding tool;
• means for producing a high-speed flow of air through said welding gap;
• said elastically compressible strip protruding radially from said axis a greater distance than said welding edge, said elastically compressible strip and said high-speed flow of air being effective to hold said leading edge against said opposing roller for a first distance past said welding gap and to permit said leading edge to separate from said opposing roller at a second distance;
• and
• a guide plate tangentially disposed adjacent said opposing roller at a tangential position beyond said second distance where said leading edge of said web lifts off said opposing roller and effective to guide said leading edge to said second conveying means.