Bag folding machine

A bag folding machine comprising:

• (a) a pair of folding drums having equal sizes and mirror-image constructions and supported for rotation and means for rotating the drums at the same rate but in opposite directions,
• (b) longitudinal grooves formed in the circumferences of the folding drums at equal circumferential intervals, respectively, each said groove having a pair of side walls,
• (c) swing grippers supported for swing motion in the longitudinal grooves, respectively, said swing grippers having the proximal ends thereof fixed to shafts passing through said longitudinal grooves, said shafts being interlockingly rotatable in said longitudinal grooves with the rotation of said folding drums for periodically pivoting said swing grippers toward a radially outermost end of one of said side walls of each said groove,
• (d) thrusting and cutting blades provided in the circumferences of the folding drums, respectively, said thrusting and cutting blades being of the same number as said longitudinal grooves, each said thrusting and cutting blade being disposed in between each two of said longitudinal grooves of the same folding drum, each said thrusting and cutting blade having a wedge-like head,
• (e) suction means for holding tubes onto the circumferences of said folding drums by suction, said suction means comprising suction passages which each have one end thereof opened at the distal end of a respective said thrusting and cutting blades and another end communicating with a longitudinal suction passage formed in a respective said folding drum and suction passages which each have one end thereof opened at a radially outermost end of one of said side walls of each said groove and another end communicating with a respective longitudinal suction passage, and
• (f) cutting blades disposed along the circumference of said folding drums for cutting tubes cooperatively with said thrusting and cutting blades,
• a rotational phase difference between the folding drums being determined so that the longitudinal grooves and the thrusting and cutting blades of one folding drum coincide with the thrusting and cutting blades and longitudinal grooves of the other folding drum at the point of tangency of the folding drums so as to firmly hold cut tubes on the circumferences of said folding drums by the coupled effect of said swing grippers and said suction passages.