Appartus for, and method of, producing a bag from paper, and paper bag

Abstract

A bag machine for production of bags made of paper material includes an unwinding device to unwind and feed paper material in a transport direction (x), a device to produce weakening lines partially offset in direction (x), so that a first wall of the bag continues in at least one tab that extends beyond a second wall, a tube-forming device, in which side areas are folded to form an overlapping area, a separation device to separate tube sections along the weakening lines, and a bottom formation device, in which areas of a leading end of the tube section are folded and fastened onto an outer wall thereof. The machine has a device for application of adhesive surfaces to the paper material, with which an adhesive surface is applied to an area of the paper material that represents the side of the tab facing the second wall in the finished bag.

Claims

1. A bag machine for production of bags made of paper material, comprising: an unwinding device to unwind and feed the paper material in a transport direction (x); a device for producing a perforation, such that portions of the perforation are offset relative to each other in the transport direction (x), so that a first wall of a finished bag continues in at least one tab, which extends beyond a second wall thereof; a tube formation device to form a tube, with which the side areas of the sheet are folded and joined to each other to form an overlapping area; a separation device to separate a tube section along the perforation from the tube; a bottom formation device, with which areas of a leading end of the tube section are folded and fastened to an outer wall of the tube section; and a device for applying to the paper material, directly adjacent to the perforation, an adhesive surface, the adhesive surface being (i) applied to an area of the paper material that represents a side of the tab facing the second wall in the finished bag and (ii) a piece of material having adhesive on bot sides thereof, one side of which is covered with a cover sheet, the device for applying the adhesive surface being located upstream, in the transport direction (x), of the tube formation device.

2. The bag machine according to claim 1, wherein for production of bags having gussets, the adhesive surface is applied to an area of the tab that is not covered by the gussets.

3. The bag machine according to claim 1, further comprising a device for producing folding lines, wherein the device for applying the adhesive surface is located downstream, in the transport direction (x), of the device for producing folding lines.

4. The bag machine according to claim 1, further comprising a longitudinal gluing device arranged upstream, in the transport direction (x), of the tube formation device, wherein the device for applying the adhesive surface is located adjacent the longitudinal gluing device.

5. The bag machine according to claim 1, wherein the device for applying the adhesive surface is synchronized with at least one of a cutting tool and a perforation tool associated with the device for producing the perforation.

6. The bag machine according to claim 1, wherein the device for applying the adhesive surface is movable across the transport direction (x) of the paper material or the bag.

7. The bag machine according to claim 1, wherein the device for applying the adhesive surface includes an unwinding device, in which a roll with a strip, on which adhesive labels are applied, is insertable.

8. A method for production of bags made of paper material, said method comprising the following steps: unwinding a sheet of the paper material and feeding the unwound sheet of the paper material in a transport direction (x); introducing a perforation, such that portions of the perforation are offset relative to each other in the transport direction (x), so that a first wall of a finished bag continues in at least a tab that extends beyond a second wall thereof; forming a tube, in which side areas of the sheet are folded to form an overlapping area and join to each other; separating tube sections along the perforation from the tube; forming a bottom, with a leading end of the tube section being folded and fastened onto an outer wall of the tube section; and applying to the sheet, directly adjacent to the perforation, an adhesive surface, the adhesive surface being (i) applied to an area of the paper material that represents a side of the tab facing the second wall in the finished bag and (ii) a piece of material having adhesive on both sides thereof, one side of which is covered with a cover sheet, the step of applying the adhesive surface being performed before the step of forming the tube.

9. The method according to claim 8, wherein during production of bags having gussets, the adhesive surface is applied to an area of the tab that is not covered by the gussets.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The individual figures show:

(2) FIG. 1 Top view of the sheet-like paper material before tube formation

(3) FIG. 2 Top view of tube formation

(4) FIG. 3 Top view of a finished bag

(5) FIG. 4 View of a finished bag from below

(6) FIG. 5 Side view of a bag machine according to the invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

(8) FIG. 1 shows sheet-like paper material 1 before actual formation, which is guided through the bag machine in transport direction x. Perforations 2 have already been introduced to this paper material 1, which essentially run across the transport direction x. It is apparent that sections of the perforations are arranged in transport direction x at different positions. Thus, the section 2a is shifted relative to the sections 2b in the transport direction. The lines running in the longitudinal direction show the longitudinal folding edges 3. It is apparent in the figure that the offset of sections 2a and 2b occurs in the region of these folding edges. The folding lines 4, around which the sheet-like material is folded during tube formation, if gusseted bags are to be produced, is shown with a dotted line.

(9) The surface 5 designates the inside 5 of the lower wall. The surfaces 6a and 6b, after tube formation, represent the inside of the upper wall. In the depicted practical example, adhesive surfaces 7 are shown in surface 6a. The adhesive surfaces 7 are then applied to the paper material, so that they lie in the transport direction x fully in front of the perforation section 2b. However, only a relatively small surface should be present between the adhesive surfaces 7 and section 2b, so that adhesive surfaces 7 and section 2b are adjacent to each other. An adhesive surface 7 can additionally or as an alternative be arranged on surface 6b. The double arrow y indicates that the adhesive surface, as required, can be moved across the transport direction x and can therefore be arranged at any location.

(10) FIG. 2 shows a tube formation process. By means of appropriate guide elements in the bag machine, for example, by means of correspondingly bent guide plates, the sheet-like paper material 1 is folded. For this purpose, the sheet edges 8a, 8b are guided by the guide elements, so that they are positioned on surface 5, in which case folds are formed along the longitudinal folding edges 3. The insertion of gussets is known to one skilled in the art and is therefore not further described here.

(11) During folding, the sheet edge 8b is first folded, followed by the sheet edge 8a, so that the edge 8a, after tube formation, remains visible. However, it is also conceivable that edge 8a is folded first and then edge 8b. In the top view of the tube 9 just formed, it is conspicuous that the perforation section 2b is visible, since it is introduced to the wall now lying on top. The adhesive surface 7 is now also situated in this wall lying on top. However, since it is situated in the tube interior and is not visible in the top view, it is shown with a dotted line in FIG. 2. The perforation section 2a is now also not visible, since the surface 5, into which it is introduced, is now covered by the surfaces 6a and 6b, so that section 2a is also shown with a dotted line. It is apparent in FIG. 2 that the extent of the adhesive surface 7 in transport direction x advantageously at a maximum is equal to the difference in positions of sections 2a and 2b. In this way, the adhesive surface is restricted to the area of tab 10, which is apparent in FIGS. 3 and 4.

(12) FIG. 3 shows the tube 9 after it has been separated into tube sections. This separation generally occurs by guiding the tube through a first roll gap. The rolls of an additional roll gap following in the transport direction and separated from the first roll gap by at least one tube section length, are driven with higher speed than the rolls of the first roll gap. When the rolls of the additional roll gap grasp the leading end of tube 9, it tears along the weakening line of perforation 2. After separation, the leading end of the tube section, which consists at least of an extension of lower surface 5, is folded and fastened onto the upper wall, which includes surfaces 6a and b.

(13) The folding edges 3 now form the longitudinal sides of bag 11. Projection of the perforation section 2a of surface 5 and perforation section 2b now delimit the tab 10, on whose inside the adhesive surface 7 is now arranged.

(14) FIG. 4 shows the same bag as in FIG. 3, merely turned around the longitudinal axis, so that the bottom is visible.

(15) FIG. 5 schematically depicts a bag machine 20 according to the invention. The sheet-like paper material 21 is wound on a roll in unwinding station 22 and is guided from there by deflection rolls 23 to the perforation station 24 (not further shown).

(16) From there the sheet-like material goes to a counter-roll 25. This roll serves as counter-position for the labeling station 26. A roll 27 is situated in this station with a strip, on which individual labels are applied, which are adhesive on both sides. This strip is unwound from roll 27 in cycles. In each cycle, an individual label is applied at a precalculated time to the sheet-like paper material 1. The pressure element 29 is used here to press on the label, which is formed roll-like in the depicted variant. The strip, which now no longer carries labels, is then wound onto roll 28 and can be disposed of from there. The sheet-like paper material provided with labels as described then goes to the tube-forming station 30 (not further shown) and then to additional stations for production of the bag. The rolls of the labeling station 26 can preferably be driven independently of the rest of the machine. The drive, however, is preferably controlled by control of the bag machine. A separate sensor for the drive, however, is also conceivable.

(17) The labeling station can be provided as an optional attachment, which can be mounted on the side walls of the machine frame of the bag machine.

(18) The invention being thus described, it will be apparent that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be recognized by one skilled in the art are intended to be included within the scope of the following claims.