Apparatus for manufacture of a plastic bag with standup bottom wall

Abstract

A flat plastic bag is formed from a side gusseted tubular web. The bag is formed with an open end and a opposite spaced end seal. Hinge crease patterns are formed in each of the gusseted portions at the bottom end of the bag. The pattern includes a two ridge upper leg and a three ridge bottom leg which are formed by a cold sealing process. A bag making machine includes a web supply which is passed through a web feed supply section to form the gusseted web. The gusseted web is sent through a forming section. The segment is first formed with the patterns of two bags in immediately adjacent relationship and located to the opposite sides of a common line defining the end of the adjacent bags. The web is formed into two bag segments with the creases located at each of the segment ends. The web is passed through a unit creating the seal and simultaneously severing the upstream segment. The segments are stacked on a table with each stack sequentially transferred to a punch unit which severs the center portion of the segment to define open bag ends adjacent each other with interconnections to maintain the stack relationship between the separated bags. The formed stack is passed through a separation unit which removes the cut portions thereby separating the bags for transport to a conveyor. The bag may be formed with ventilation openings at the punch unit. The crease pattern with the bottom portion includes a plurality of creases to ensure the proper location of at least one crease within the gusseted portion to ensure easy opening of the plastic bag.