GB684890A - Improvements in or relating to methods of and apparatus for forming a paper or like bag - Google Patents

Abstract

684,890. Making paper and like bags. ROBINSON (CANADA) Ltd., E. S. & A. Feb. 9, 1951 [Feb. 9, 1950], No. 3216/51. Class 94(ii) Relates to a method of forming a self-opening satchel bottom bag from a tube with side bellows folds, or of converting an already formed plain square bottom bag to a self-opening satchel bottom bag. As shown in Fig. 1 a plain square bottom type bag 10 comprises a length of flattened tubular material having opposed bellows folds 11, the end 12 at the bottom forming portion being sealed and folded back about a fold line 14 and secured to the adjacent side wall by an adhesive. Spaced parallel crease lines 15 and 16 are also provided. A forming anvil 18 is movable toward the bottom edge 14 of the bag, and two opening blade mechanisms 21 are arranged on opposite sides of the bag. The mechanisms 21, Fig. 16, comprise blade-like members 23, 24 mounted for coaxial contrarotating movement on a sleeve 26, and a shaft 25 respectively, means being provided to rotate the sleeve 26 and shaft 25 relative to each other in the desired manner. When the blade mechanisms 21 are moved to their innermost position, adjacent the inner limits of the bellows folds 11, the anvil member 18 is moved toward the bottom fold 14 to grip the bottom folded portions of the bag between the edge of the anvil and the edges of the folding blades 23, 24, Fig. 5. The blades 23, 24, are then opened, Fig. 7 and 8, to produce a square flat bottom in the bag 10, Fig. 13 and 14, comprising rectangular areas 33, 34, extending between the initial fold line 14 and the transverse crease lines 15, the bottom ends of the bellows folds being formed into connected pairs of triangular shaped fold portions 35, 36. The blades 23, 24, are moved to the position shown in Fig. 9 and force the bottom forming portions 33, 34 against the surfaces 19, 20, of the anvil member 18, causing the side walls of the bag to collapse inwardly, and a pair of opposed creaser members 41, 42, are moved into pressing engagement with the bottom of the bag. This produces the triangular fold portions 39, 40, and 47, 48, in the bag. After the members 41, 42 are withdrawn the blade 23 is moved .clockwise, Fig. 11, to position the folded bottom portion at an angle to the plane of the collapsed body portion, and the blade mechanisms 21 are then withdrawn and the anvil member 18 retracted. The 'bag is then passed between a pair of endless belts, Fig. 12 (not shown) to flatten the bottom of the bag against the body. An alternative method of producing a bag having the same bottom formation is described, Fig. 17 to 30 (not shown). The portion 12 is not initially bent over and secured to the side wall as in Fig. 1, but the anvil member comprises two jaws which grip the portion 12 during the folding operations, after which this protruding portion is attached to the bottom forming portion of the bag.