Patent GB-677256-A (GB)
Title: Improvements in or relating to bag bottom forming apparatus
IPC: B31B37/00
Filed: 1949-09-02
Abstract: 677.256. Making paper bags. ST. REGIS PAPER CO. Sept. 2, 1949 [Sept. 11, 1948], No. 22780/49. Class 94(ii) A machine for forming paper bags, particularly multi-ply valve-bags, comprises means for conveying a succession of bag tubes over a predetermined path at a constant speed ratio with respect to spaced operating-devices such as slitters, spreaders, adhesive-applying and folding means, the devices being connected to the conveying means for actuation in timed relationship. As shown, a pair of endless conveyer chains 31, 32 is fitted with spaced pairs of baggrippers 37 each comprising a fixed and a movable jaw, the latter being normally spring-closed and opened by cam-action to receive and grasp a flattened bag-tube 55, and to release the same after the bag-forming operation is completed. The stages in the formation of a bag are illustrated at a-h. in Fig. 17. The flattened tube is first moved to a location 56 where slits 55a, Fig. 17(a) are formed, the slitting being effected by a pair of rotary knives 56a co-operating with rotary grooved backing-members 58. The tube next passes between a pair of scoring-rollers 71 and grooved backing- rollers 73 to form a folding line 72, Fig. 17(b), near each end of the tube. The flattened tube ends are next bent up by shoes 83, 84 and partially opened by means of suction-cups 85, 86 before passing to spreader units 82, Fig. 3. These comprise pairs of oppositely-rotating fingers shown in Fig. 7. A first pair 104, 105 enters the tube to form the side flaps 108, 109, Fig. 17(d) after which a second pair 112, 113 enters to form the leading corner flap 110. The trailing corner flap 111 is then spread by a third pair of fingers 116. 117. Eccentric toothed gearing, Figs. 10, 11, (not shown) is provided so that the fingers 112, 113, move at greatest speed when contacting the leading corner flap 110; this drive also includes a yielding spring coupling, Figs. 8, 9, (not shown). The fingers of a set are adjustably mounted on their shaft. The flattened tube then passes between pressing rollers 162, 163 to iron the spread corner and side flaps. The bottom and top fold-lines 164, Fig. 17(e), are then formed by pairs of scoring- rollers 166, 167 after which adhesive is applied to preselected areas of the corner and side flaps of the spread bag. Mechanism is next reached for forming and applying a bag valve sleeve 186, Fig. 17(g), after which folding along the lines 164 is effected to form the finished bottom and top as seen in Fig. 17(h). Referring to Fig. 2, the strip material 188a for forming the bag valve sleeves is fed from a stockroll 188 over adhesive applyer 198 and rolls 190, 191, 192 to a shaping mandrel 193, and after severing, the sleeves are applied to the bags by means of a roller 189. The bags are then passed between rollers 244, 245, which exert light pressure on the pasted seams, on to a delivery-conveyer 247. Differential gear apparatus such as 68, 100, 149a, Fig. 1, manually adjustable during operation, provides for obtaining the required phase relationship of the various operations. The machine is adjustable for different length and width of bag.