GB1316669A - Bag making machine - Google Patents

Abstract

1316669 Bag making machines A L ROSS 29 July 1970 36791/70 Heading B5D [Also in Division B8] In making bags from a paper web by folding the web to tubular form and finally rupturing the web along perforated lines to form separate bags, a small transverse section of the web remains unperforated until the web passes through that part of the machine in which it is subjected to the highest pulling stresses. The longitudinal edges of the web are adhesively secured to form the tube. The web W from a roll (not shown) is fed round rolls 9 and 10 to an anvil roll 11 when it is perforated by a roll 12 across sections a and d leaving a central part 1<SP>1</SP> intact (see Fig. 12). Feed rolls 3 provide the draw-off tension and pull the web over a tube former 22, the part 1<SP>1</SP> being then perforated by a roll 121. Subsequently, the tube passes to a pinch roll assembly PR where second feed rolls 5 pass the web to rolls 6, 6<SP>1</SP> rotating at a slower surface speed than a main cylinder MC against the surface of which the tube is periodically gripped by a pinch bar 70 to cause rupturing at a line R adjacent a roll 80. Cam means ensures that the rolls 6, 6<SP>1</SP> grip the web before the bar 70 clamps the web against the cylinder MC and do not release the web until after each bag has been separated, when belts 33, 34 drive the bag at a faster speed to a tucker blade 37. Alternatively, the bottom of the bag may be unclosed. The pinch bar 70 has a flexible removable cover and is slightly spiralled to ensure progressive rupturing across the width of the web. Power is transmitted from an electric motor to cylinder MC, the other mechanisms being driven therefrom by chain and gear drives as shown in Fig. 11. The speeds of the first and second feed rolls 3, 5 and of the perforation rolls is the same, while the speed of the pinch rolls is slower. The speed of the main cylinder is faster than that of the feed rolls. Bag-width can be varied by using a different width of web and bag length is adjustable by varying the roller speeds. The perforator blades are set at an angle z between 15 and 45 degrees to the radial line rr through the roller axis, this ensures that the blades leave the web without snagging. The blades are adjustably mounted along their roller shafts and blades forming the corners y (Fig. 13) are also mounted on the same shafts. The bag may be of paper, glassine, a foil, a plastic, or a synthetic material.