WO2002030660A1

WO2002030660A1 - Sack bottom manufacturing equipment

Info

Publication number: WO2002030660A1
Application number: PCT/FI2001/000831
Authority: WO
Inventors: Valter Sievers
Original assignee: Upm-Kymmene Corporation
Priority date: 2000-10-12
Filing date: 2001-09-24
Publication date: 2002-04-18
Also published as: FI20002246A; AU2001291908A1; FI20002246A0

Abstract

The invention relates to equipment for manufacturing the bottom of a cross-bottom sack. It comprises means (2) for attaching the bottom patch (6) to the bottom of a flattened sack so that the first side edge of the patch protrudes beyond the edge of the bottom and has been folded against the first side (9) of the wall of the sack. In addition, the equipment comprises means (2, 10, 11) for attaching the bottom patch (6) to the bottom in such a way that there is a protruding part (6.2) at one side edge of the patch, which part protrudes beyond the other edge of the bottom and is folded against the other side (5) of the sack wall.

Description

SACK BOTTOM MANUFACTURING EQUIPMENT

Technical field of the invention

The present invention relates to sack manufacture and concerns the equipment that is used in the manufacture of the bottom of a cross-bottom sack, by means of which equipment a bottom patch is attached to the flat bottom. The bottom patch protects, reinforces and seals the bottom. The invention can be used particularly in the manufacture of paper sacks.

Background technology Sacks are manufactured in such a way that at least one end of the blank that has been cut from a flattened tube is closed to form the bottom. The paper tube is formed by joining the edges of the paper web together. The tube may comprise various plies one inside the other. A flat bottom can be formed in such a way that the triangular end flaps are folded inwards from the edges of the blank, and on top of these, side strips are folded from the sides. In a valve sack the bottom is formed at both ends of the blank, but on one bottom, the gap between the folds is left open at one end so as to form a filling valve. Usually a so-called bottom patch is pasted to the bottom, which patch protects, reinforces and seals the bottom. In a finished sack, the bottoms are turned against the wall of the flattened sack. The bottoms are formed by means of a so-called bottomer.

With the bottomers used on present-day paper sack manufacturing lines, the bqttom patch can usually be pasted only on the area of the bottom and also over one side edge, if desired.

Description of the invention The current invention relates to equipment as claimed in claim 1, for use in the manufacture of the sack bottom. Certain other preferred embodiments of the invention are described in the other claims.

The invention enables the manufacture of cross-bottom sacks with a bottom patch that has been attached over both side edges of the bottom. A patch of this kind significantly reinforces the edges of the sack bottom.

A valve sack may have a bottom patch as claimed in the invention on either bottom or on both bottoms. Most simply there is a patch only on the valve bottom. Then it reinforces the sack at the filling stage when the sack is suspended from the filling pipe. An upright sack is best kept with the valve bottom against the ground. In this case, too, the protective patch on the valve bottom is important. The width of the part of the bottom patch that is folded over the bottom edge is, for example, 10 - 50% of the width of the bottom patch, typically approximately 20%.

Equipment as claimed in the invention can be added to existing manufacturing lines as an additional unit. In particular, it can be incorporated after the traditional bottomer in which the bottom is formed horizontally. In this case the drive is most advantageously a servo drive that is synchronised with the speed of the bottomer line.

Figures The attached figures form a part of the detailed description of one embodiment of the invention presented below.

Figure 1 shows one example of bottom patch attaching equipment relating to the invention, seen from the side. In the figure, the sacks travel from right to left.

Figure 2 shows a sack moving in the equipment as shown in figure 1 at different stages, seen from above.

Figure 3 shows the sack correspondingly at different stages, seen from the right hand side.

Detailed description of one embodiment

The last unit of the manufacturing line of a conventional cross-bottom sack 1 is the so-called bottomer 2, in which the flat bottoms are finally formed. At one end of the valve bottom 3 of the sack, a filling valve has been formed by leaving the side strips unpasted to the end flaps. The other bottom 4 is completely closed.

The sacks moving on the line have been flattened and they travel horizontally.

The longitudinal direction of the sacks is transverse to the direction of travel. The bottoms that have been formed are folded against the underside 5 of the wall.

At the bottomer 2, bottom patches 6, 7 are also pasted to the bottoms 3, 4 of the sack. To form the bottom patch, the bottom patch web 8, which is wider than the bottom, is brought into position at both bottoms. A piece that is the length of the bottom is cut off the web, paste is spread on it in the form of strips of paste that are in the direction of travel, and the piece is pressed against the bottom. The outer edges of both bottom patches protrude beyond the outer edges of the bottom. Paste is also spread on this protruding part 6.1, 7.1, most preferably in such a way that the paste starts right from the edge. The part protruding beyond the edge is folded around the edge of the bottom, against the topside 9 of the wall and is pressed onto it. In the bottom patch 7 at the closed end, the inner edge, i.e. the edge that is next to the wall, is placed at the edge of the bottom. Most preferably, it is provided with paste starting right from the edge. In the valve bottom patch 6, also the inner edge protrudes beyond the edge of the bottom. No paste is spread on this protruding part 6.2 on the bottomer.

In addition, a manufacturing line as claimed in figure 1 is provided with a bottom turning device 10 and a pasting device 11 for the protruding part 6.2 of the bottom patch for the valve bottom. These are used to turn the bottoms of the sack 1, coming from, the bottomer 2, against the topside 9 of the wall, and to paste the protruding part over the edge of the bottom 3.

In the turning device 10, on the track along which the patches travel, there are curved guide blocks that turn the bottoms 3, 4 from the underside 5 of the wall against its topside 9. The protruding part 6.2 of the valve bottom patch 6 is now outside the plane of the wall.

The pasting device 11 is provided with a pasting unit 12, by means of which paste can be spread on the wall at the point where the protruding part 6.2 is to be pasted, at a suitable distance (e.g. approximately 10 mm) from the edge of the bottom. The paste strip is slightly (e.g. approximately 20 mm) shorter than the bottom patch. The pasting unit is provided, at the position of the additional strip, with an upper roll 13 and a lower roll 14, to which a paste belt or band has been attached, on which belt or band there is already pasted a pasting rubber that is the width and length of the desired paste strip. On this pasting rubber paste is spread using the paste roll 15. These rolls have been mounted on the body 16, which also incorporates a paste reservoir under the pasting roll. The lower roll is connected to the drive 17. The drive power can be taken from the conveyor's drive equipment on the line or it can be arranged separately. The upper roll is only used when necessary, as a weight. In particular, a servo drive synchronised with the speed of the line can be used.

The roll body 16 can be moved vertically, so that the lower roll 14 can if desired be released from the pasting position, when manufacturing sacks without the protruding part 6.2, or if for some reason the protruding part is not pasted, at least at this stage. Finally the protruding part 6.2 is folded over the edge of the bottom and pressed against the underside 5 of the wall, by means of the folding device 18. It has folding blocks that are curved in the direction of travel, which blocks also press the protruding part against the wall.

Claims

1. Equipment for manufacturing the bottom of a cross-bottom sack, comprising means (2) for attaching the bottom patch (6) to the bottom of a flattened sack, in such a way that the first side edge of the patch protrudes beyond the edge of the bottom and is folded against the first side (9) of the wall of the sack, characterised in that the equipment has means (2, 10, 11) for attaching the bottom patch (6) to the bottom so that there is a protruding part (6.2) at one side edge of the patch, which part protrudes beyond one edge of the bottom and is folded against the other side (5) of the wall of the sack.

2. Equipment as claimed in claim 1, comprising means (2) for attaching the bottom patch to the bottom, which has been folded against one side of the wall of the sack, in such a way that the first side edge of the patch protrudes beyond the outer edge of the bottom and has been folded against the first side of the wall of the sack.

3. Equipment as claimed in claim 2, comprising means (10) for turning the bottom and the bottom patch attached to it from the first side of the wall to the other side of the wall, and after that, folding means (18) for folding the protruding part against the other side of the wall.

4. Equipment as claimed in claim 3, comprising, between the turning means (10) and the folding means (18), means (12) for spreading paste on the surface of the additional strip that comes against the wall.

5. '^•Equipment as claimed in claim 4, comprising, as part of its pasting means, a spreading roll (14) to spread paste on the wall of the sack or the protruding part, most preferably on the wall of the sack.

6. Equipment as claimed in claim 5, comprising means (15) for transferring paste from the paste container onto the spreading roll.

7. Equipment as claimed in claim 5 or 6, comprising a second roll (13), through which second roll and the spreading roll the bottom passes.

8. Equipment as claimed in any of the claims 5 to 7, in which the spreading roll (14) is mounted in a movable body.

9. A method for attaching the bottom patch to the bottom of a flattened cross- bottom sack so that the first side edge of the patch protrudes beyond the edge of the bottom and has been turned against the first side of the wall of the sack, characterised in that a bottom patch is attached to the bottom, and at one side edge of the bottom patch there is a protruding part that protrudes beyond one edge of the bottom, and the additional strip is turned against the other side of the wall of the sack.

10. Equipment as claimed in claim 7, in which a bottom patch is attached to the bottom, and the width of the additional strip in the said bottom patch is 10-50%> of the width of the bottom, typically approximately 20%.