| 摘要 |
A method and apparatus for forming multiple bags of thin plastic film having interlocking rib and groove elements on the confronting top edges of the bags wherein said bags are formed from tubular film that is continuously extruded, with said tube having a first pair of rib elements, a second pair of diametrically opposed rib elements, a first pair of groove elements between said pairs of rib elements and a second pair of groove elements diametrically opposed to the first pair, with said elements in said pairs being closely spaced and being on the inner surface of the tube, with each of said pair of rib elements being aligned with each adjacent pair of groove elements as the tubing is flattened to form first and second sets of the aligned pairs of rib and groove elements, and a continuous slit being made between the elements of one layer at one set and the elements of the other layer at the other set, and with the tube being subsequently folded so that an element adjacent the slit of the first set is folded into the second set, and an element adjacent the slit of the second set is folded into the first set so as to form two continuous strips of double interlocking profile film. |
