Making block bottom plastics bag - using variable size stretching frame

摘要

An appts. for making commercial bags of thin tubular film, esp. plastics sheet. comprises: a tension compensator mounted on a stable frame for keeping the tubular material tensioned; an appts for expanding and stretching the tube, comprising a solid geometrical object with >=1 flat sides and varying dimensions; a device for forming a sealed filler valve on one flat side of the tube a separately supplied plastics sheet; a welding element for welding this sheet after folding onto the tubular bag; folding devices for forming the bottom folds; a welding and cutting device which cuts the tube to bag lengths and comprising welding rods with a hot cutting blade between them.