Patent GB-627820-A (GB)
Title: An improved machine for the manufacture of paper bags
IPC: B31B29/84
Filed: 1947-07-24
Abstract: 627,820. Paper bags. MACHINES AUTOMATIQUES BARDET. July 24, 1947, No. 19960. Convention date, Sept. 26, 1946. [Class 94(ii)] A bag making machine is supplied with open-ended tubes, preferably multi-ply, which are carried on posts A<SP>1</SP>-A<SP>2</SP> on the periphery of a continuously rotating cylinder R before various fixed stations until the completed bag a with two closed ends, Fig. 4, is delivered at station F. B, Figs. 8, 19, shows a feeding station for the flat tubes a; C where paper valves b are supplied; D the station at which the bottoms are gummed; E where the folds of the bottoms are opened and stuck. Bag structure.-Each tube a, Fig. 4, is stuck at the edge a<SP>1</SP>, the edges of the plies being offset, the tube ends being cut to form edges a<SP>2</SP>, and the ends folded down on one face of the tube about a crease a<SP>3</SP>, the edges a<SP>2</SP>, after being gummed, being folded about creases a<SP>8</SP>, a<SP>9</SP> upon one another and upon the parts a<SP>10</SP> included between the creases a4. A short tube b, to act as a valve, is placed on one portion a<SP>10</SP> and covered by wings a<SP>6</SP>, a<SP>7</SP> which are stuck to one another and to the valve. Mechanism.-Each post comprises two symmetrical parts A<SP>1</SP>, A<SP>2</SP>, Fig. 20, the axial spacing of which can be varied to suit the length of the bag to be made. Each part A<SP>1</SP>, A<SP>2</SP> contains mechanism to form a complete bag bottom, and one, additionally, supplies and fixes the valve b. They are each attached by means of spindles 1 to one of the two drums 2, 3 which form the cylinder R and revolve about stationary, inner drums 4, 5 mounted on a fixed shaft 6. The drums carry cams 12 which engage rods 49a to k, Fig. 23, serving to actuate the various mechanisms of the posts. The spacing between the drums A<SP>1</SP>, A<SP>2</SP>, Fig. 20, is adjusted by means of a motor N through gearing 15 and a nut 16 screwing along the shaft 6. The cylinder R is driven by a motor M through gears. The blanks for the bags are supplied on belts 25, 25a, the latter moving at a speed slightly less than that of the belt 25, so that the friction causes the blanks to bear against the conveyer belt. The blanks are directed by guides 26, one by one, on to posts A<SP>1</SP>, A<SP>2</SP>, flexible guide blades 27 being used. Each part includes a table 30, Fig: 14, which is provided with marginal elements 31, Fig. 23, lateral grippers 32, a crossbar 33 for folding and pressing a wing a<SP>6</SP>, a movable suction cup 34, combined with a vacuum pump 35, for lifting a part a<SP>6</SP> of the bag end and two stationary suction cups 36 provided to keep the underside of the bag pressed upon the table. There are also shaping members 37 for forming oblique creases a<SP>4</SP>, a bar 38, normally contained in a groove in the table 30 and designed for raising one of the end portions of the bag and an extraction bar for ejecting the completed bag. The bar 33 is moved by linkage including parallelograms 66a controlled by rods 49c, 49d from the appropriate cams 12. The pump 35 has a piston 90 moved downwards by a spring 91, to create a suction in the cups 34 and 36, when a rod 49f, in contact with one of the cams 12, is lowered. The wing a<SP>6</SP> is raised and shapers 37 now enter the bag ends to form creases. At station C a valve b is placed upon one of the tabs a<SP>10</SP>, Fig. 4, the grippers 32, previously separated to allow the positioning of the valve, being returned by their rack and pinion gear and linkage (Fig. 28 not shown) to grip the bag and the valve. To form the valve, paper strip b<SP>1</SP>, from a spool 141, Fig. 19, is fed by a gumming roller 143 through forming channel 145 where the strip is formed into a tube which is flattened on passing between rolls 140 and its upper face coated with adhesive by a gumming roller 146. Tubes, severed by knives not shown, pass down a channel 148 on to a blade 149 which presses each valve tube on to a bag on the post A<SP>1</SP>. The extremities of the channel 148 and blade 149 are cut into the shapes of combs or hands so that the fingers of the blade can ascend between those of the channel to raise the valve and press it upon the bag. The rolls 140, driven frictionally, are controlled by an electromagnet, the drive being eliminated when a bag is not in position in front of C to receive a valve. A gumming roller 110 at the station D is also lifted clear electromagnetically when the feeding table has no bag ready. On the periphery of the roller are ridges for marking each bag with fold-. ing creases as, a<SP>9</SP>. A metallic detector drum 274a, Fig. 35, is contacted by a pair of wheels 230 and excites an electromagnet which acts upon a recording device serving to close in succession two circuits 235, 236, Fig. 19, to arrest the distribution of the valves and the functioning of the gumming roller 110, respectively. The circuits are broken when a bag passes between the wheels 230 and the drum. The drum 279 of the conveyer 25a is coupled with the above gear by wheels 280, 281. The delivery device F, Fig. 19, comprises three conveyers 128, 129, 130 which have tensioning pulleys. Arms with springs press the conveyers 128, 129, against each other to grip the completed bags. The springs are adjustable. When a change is being made in the length of a bag by means of the motor N acting on the drum A<SP>2</SP>, blades 27, Fig. 35, which guide the bags on to the tables 30, may be moved laterally upon shafts 350a-350e, supported by frames 7, 8. By rotating one or more of the shafts by means of cranks 353a-c, the blades are moved laterally.