Cross-welding and perforating continuously moving double plastic film - has upper and lower welding tools with perforating knife which rotate around axes at speeds related to film speed

摘要

Equipment for welding a continuously moving double layer plastic film at right angles to the direction of movement simultaneously creates a tearoff perforation along the weld. A hot welding tool can be moved by a power source around an axis with a circumferential speed which is similar to that of the plastic film at the point of welding. After welding the tool continues to rotate around the axis at a speed related to the distance between welds. A second welding tool on the opposite side of the film is synchronised with the movement of the first tool. Both welding tools are located between two pairs of powered drive rollers for film transport. The speed of the second pair of rollers is slightly faster than that of the first or feed rollers. A perforation knife is mounted within one of the welding tools. USE/ADVANTAGE - Produces the welded seam bases of plastic bags which can then be torn off of a continuous roll. Welding seams are precisely located and are stress free. High production. rates are attained.