DE1241968B - Method and device for producing a box-shaped sack from weldable plastic - Google Patents

Description

GERMAN # f # PATENT OFFICE

EDITORIAL

German class: 39 a2 -17/02

Number: 1241968

File number: N 24702 X / 39 a2

1 241 968 filing date: March 31, 1964

Open date: June 8, 1967

There is already a cross-bottom valve bag made of weldable plastic with the hose level folded floor and its manufacturing process known in which the bottom seam is welded of the edge strips of the spread over two fold lines running in the longitudinal direction of the bag, previously to Bottom square raised hose end is formed, and which has a hose valve in one corner, which can be closed by a transverse weld after the bag has been filled. in the In the course of the manufacturing process of this known sack, several measures have to be taken in order to to prevent the undesired welding of different layers of material together. aside from that the formation of the most important weld seam, the longitudinal bottom weld seam, takes place in an unfavorable work situation. The process of making this - Sacks is therefore relatively difficult. In addition, the valve width is always the same in this bag Floor width, which is reflected in the trend towards box-shaped, which is effective today as a result of increasing palletization Sacks with a wide bottom and a narrower valve opening proves to be disadvantageous.

The invention relates to a method for producing plastic sacks with a filling opening and box-shaped bottom, which is connected by a longitudinal weld and two T-shaped Side welds are formed, in which an open hose section in a manner known per se When laid flat, it is closed by welding seams and with right-angled corner cut-outs is provided and then the hose section is pulled apart with simultaneous blowing of air into the interior of the bag, to the parallel to Hose level is laid flat floor and the then remaining corner openings by means of Welding are sealed.

The process is simple and safe, and it also allows multi-layer plastic bags to be used Inner layer that cannot be welded to one another at least on the inner surfaces, e.g. made of highly stretchable Paper to produce.

The last-mentioned feature is important, for example, when a light-sensitive product is to be packed watertight or if the sack is to be printed under the transparent sack wall and in this way against mechanical and climatic influences is protected, or if, in general, properties of different packaging materials with one another should be combined.

Another advantage of the inventive method and device for producing a box-shaped sack from weldable
plastic

-

Applicant:

Niedermayr paper goods factory
Aktiengesellschaft, Rosenheim

Named as inventor:
Dr. Friedrich Kratzert,
Schlossberg near Rosenheim

¹ S -

driving consists in the fact that with its help a bag with a box-shaped bottom is also made afterwards

ao an already welded flat bag can be produced.

The method according to the invention is described in more detail in the drawing. Show it
F i g. 1 to 4 and 6 to 16 different successive stages in the manufacture of the sack according to the invention,

5 shows a suction bar with the side facing the workpiece,

17 shows a section through the weld seam in a two-day sack and FIG

F i g. 18 is a perspective view of a filled sack made according to the invention closed filler opening.

A hose section 1 open at its ends 2 and 3 , which is made from a blown or longitudinally welded plastic hose, such as polyethylene, by cutting off the appropriate length, is initially closed at its ends by simple straight welds 4 in a known manner. Then the corners in the in F i g. 2 cut out or punched out in such a way that the cutting edges 6 α and 6 b emanating from the side edges 5 and the weld seams 4 form right angles with legs of equal length, the leg length in three corners being at most equal to half the base width minus a weld seam width and in the corner 7, which is later formed into the filling opening, corresponds to half the width of the filling opening.

Then, in a known manner, in the course of the further conveyance of the hose section, preferably through cross conveying, through guide elements

709 589/336

Claims (1)

elements inserted the ends 2 and 3 between the suction cups 8 and the slot between the support plates 9 (Fig. 3). The suction jaws are provided with suction openings 10 along their edges on the side facing the sack (Fig. 5) and grip the middle part of the erected tube section end on both sides so that the lower edges of the suction jaws along the later longitudinal edges of the bottom (line a-a in Fig. 4 ) get lost. The suction jaws 8 now move in the position shown in FIG. 6 and 7 shown way and place the middle part of the hose section end as a flat spread floor on the support plate 9, whereby at the beginning of the movement of the suction jaws 8 at the same time through the height-adjustable and laterally pivotable nozzles 11 in the area of the punchings 6 air into the The inside of the bag is blown. 8 and 9 show a tube section end after completion of this operation from above and from the side. It is also possible to place a pair of suction plates below the line a-a and, as in FIG. 10 shown to be folded down into corresponding recesses in the support plates 9. These lower suction plates can be shaped so that they cover the entire surface with which the hose wall would otherwise later rest on the support plates 9, so that these plates can be dispensed with entirely (FIG. 11). Finally, pairs of suction plates can be attached simultaneously above and below line a-a and also connected to one another in a hinge-like manner at the level of line a-a. On the side facing the workpiece, the suction jaws 8 can also be provided with a covering made of elastic material which, starting from the center, is slightly ground in the direction of the recesses 6 of the hose section with a slight curvature. With suction cups 8 designed in this way, the suction openings 10 located in the middle are initially completely or partially squeezed when pressed against the hose section 1, while the full suction effect immediately sets in at the suction openings that are closest to the recesses 6 and thus the air inlet openings. As a result, a slightly rolling suction movement which is advantageous for spreading apart is achieved. Welding jaws 12, which are designed to be slidable on their undersides, are then placed at the level of lines b-b and c-c on the free, not yet flat parts of the hose section end. While they depress the hose section end at these points, they slide towards each other in the direction of the cut edges 6 a and 6 b. The cut edges 6 a and 6 b stand up, lie against one another and are welded to one another by the welding jaws 12 (FIGS. 12 and 13). The connection of the cut edges 6 a and 6 b to one another can also be done by radiation welding. In this case, the jaws 12 are designed as pure holding organs. In the corner of the filling opening 7, the cut edges 6 a and 6 b are aligned according to the desired corner tip length determined by the depth of cut. The welding jaws 12 are designed in this case in such a way that the corners 13 (FIG. 14) are only welded in a triangular shape. The possible opening width depends on the one hand on the base width and on the other hand on the length of the corner tip. Since the upward extensions of the side edges 14 of the corner tip form a right-angled triangle, the longer the corner tip is selected, the smaller the width of the filling opening is the same bottom width. In cases in which a tube or hose valve protruding into the interior of the sack is desired, a narrow tube section can be introduced into the opening between the cut edges 6a and 6b in a manner not described here and welded to these cut edges. If this valve tube protruding into the interior of the bag is kept narrower than the opening formed by the two cut edges 6 a and 6 b, lateral channels are created between this and the inserted valve tube through which air can escape during filling and which through later closing of the valve Cross weld to be closed. After the cutting edges 6 a and 6 b have been welded together, the welding jaws 12 and the suction plates 8 return to their starting position, and the finished sack is transported to a storage table. When producing multi-layer plastic sacks with an inner layer that cannot be welded at least on the inner surfaces, one starts with a tube section open at both ends as shown in FIG. 15, in which, in a manner not described in detail here, for example, a tube section LS of the same width made of highly stretchable paper is drawn in, the ends 16 and 17 of which are shortened by about 5 to 10 mm compared to the ends 2 and 3 of the outer layer 1, and which already has punched holes 18 , which are slightly larger than the cutouts 6a and 6b required for the outer layer 1. The multi-layer tube section prepared in this way is then welded at its ends along the line dd (FIG. 16) by a wide weld seam so that the inner paper layer with its ends 16 and 17 just protrudes a little into the weld seam and onto it Way is sealed in (Fig. 17). At the same time, as indicated by crosses in FIG. 16, the inner layer is attached to the inside of the outer layer by point seals 19 made from the outside, namely along the edges of the cutouts 18 and approximately at the points where the suction slots 10 of the suction jaws 8 will later attack on the outside walls. These stitching points ensure that the inner layer carries out the same folding movements as the outer layer in the further course of processing. In the same way, when producing open-topped bags, the inner layer can be joined to the outer layer along the filling edge. The further process steps take place in the manner already described, the welding of the cut edges 6 a and 6 b to one another analogous to the execution of the weld seam along the line d-d in FIG. 16 takes place. Patent claims: 1. A method for producing a box-shaped sack made of weldable plastic, the bottom of which is formed by a longitudinal weld seam and two side welds adjoining this T-shaped, characterized in that an open tube section (1) in a manner known per se in flat