GB2329359A

GB2329359A - Forming fold lines in continuously fed flat workpieces

Info

Publication number: GB2329359A
Application number: GB9820104A
Authority: GB
Inventors: Horst Rautenberg
Original assignee: Windmoeller and Hoelscher KG
Current assignee: Windmoeller and Hoelscher KG
Priority date: 1997-09-23
Filing date: 1998-09-15
Publication date: 1999-03-24
Anticipated expiration: 2018-09-15
Also published as: IT1303522B1; GB9820104D0; FR2768652A1; JP4707202B2; DE19741937A1; JPH11165294A; GB2329359B; FR2768652B1; DE19741937C2; ITBZ980054A1

Abstract

Continuously fed flat workpieces 14 have indentations 15 forming fold lines pressed into the workpieces with a scoring tool, wherein the fold lines 15 are marked only in the zones of their ends. Apparatus for forming the fold lines comprises a cutter-type ridge rotating on a cylindrical cover shell 11, which presses the indentations 15 into the workpieces 14 supported on a roller 18 with an elastomeric shell. The invention is particularly used for forming the bottom fold lines in cross bottom sacks or bags manufactured from transversely fed tubular sections.

Description

2329359 Method and apparatus for forming fold lines in continuously fed

flat work pieces

FIELD OF THE INVENTION

The invention concerns a method for forming fold lines in continuously fed flat workpieces, preferably in laid flat tubular sections as prescored lines for the bottoms to be opened out, wherein indentations forming the fold lines are pressed into the workpiece with a scoring tool.

PRIOR ART

From DE-PS 12 99 514, there is known a scoring apparatus for forming the bottom main folds, in machines for laying cross bottoms, for manufacturing sacks or bags out of transversely fed tubular sections, wherein the scoring tool consists of a rotating scoring disk with a knifetype cutter which cooperates with a counter disk provided with a scoring groove. With such a scoring apparatus, the central bottom folds 2 are scored of the tubular sections 1, made of paper or a synthetic film, shown in Figures 6 to 8 of the drawings. In this representation, Figure 6 shows a top view of a flat lying tubular section, Figure 7 shows a section through the tubular section along line VII - VII in Figure 6, and Figure 8 shows a section corresponding to Figure 7 through the tubular section with the opened-out bottoms disposed at right angles to the side walls which lie flat on top of one another. As shown in Figure 7, with a scoring apparatus of the kind known from the DE-PS 12 99 514 the central bottom folds 2 are prescored in such a way that two corrugation-type scored grooves are obtained which nest in one another'. Now when the bottoms are opened out in the usual way, the bottom parts 3, 4 are folded over in opposite directions with respect to one another, and in this process the upper bottom half 3 is folded in the scored groove 2 because this constitutes a preliminary break corres ponding to the shape of the fold. However, problems do arise in the folding of the bottom half since this is effected, in the way shown in Figure 8, in the opposite direction to the indentation 2 which forms, as it were, a stiffening corrugation so that the folding is effected next to the scored groove 2, which opposes any folding therein.

In a scoring device known from the DE-UM-19 64 069, there are provided disposed closely next to one another two grooving cutters which cooperate with a grooving disk provided with two approximately complementary grooves, between which grooves there is disposed a cutter-type ridge, so that scored lines consisting of two grooves parallel to one another are pressed into the tubular section to be provided with the fold lines, between which scored lines a groove is formed in the opposite direction. If tubular sections, provided with such scored lines, are opened out into bottoms the folding is obtained along a groove which has the right arcuate part corresponding to the folding. Since, in the case of the fold lines pressed in with this folding apparatus, the folding is effected along the fold lines pressed in the correct lateral position there occurs a corresponding offset of the folds of the bottom halves opened out in the opposite direction.

OBJECT OF THE INVENTION It is the object of the invention to create a method of the kind indicated in the Field of the Invention above, wherein fold lines can be arranged in flat workpieces with sides lying on top of one another, for instance in flat lying tubular sections, so as to allow the folds corresponding to one another to be executed in the two sides.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention, this problem is solved in a method for forming fold lines in continuously fed flat workpieces, wherein indentations forming the fold lines are pressed into the workpiece with a scoring tool, and the fold lines are marked only in the zones of their ends by scored lines. It has been shown, surprisingly, that by marking the fold lines only in the zone of their ends it was also possible to effect folding, true to position, in the side of the two-layered workpiece or of the tubular section, wherein the scored line consisting of a groove was on the opposite side to the fold. The fold line is also marked by any prescoring which is incorrect in position, so that a fold is formed between the scored lines that is true to position. In the prescoring of the central bottom folds of tubular sections this means that the side of the tubular section which, after the bottom has been opened out, is provided with the start of an indentation in the opposite direction to the fold also receives a central bottom fold in the correct position.

A second aspect of the invention provides an apparatus for scoring continuously fed flat workpieces for forming fold lines, comprising a cutter-type ridge rotating on a cylindrical cover shell, which presses the indentation into the workpiece supported on a rotating bearing means consisting of a roller with an elastomeric shell.

Because of the elasticity of the elastomeric shell of the counter roller, the apparatus in accordance with the invention presses only relatively shallow scored lines into the workpiece which, surprisingly, ensure good folding along these scored lines. The scored line whose groove points in the opposite direction to the arc created by the folding also allows the fold line to be applied in its correct position. The apparatus in accordance with the invention is therefore particularly suitable in the manufacture of bags, for obtaining the diagonal indentations in the tubular sections, for forming the fold lines for the corner wraps or triangular pockets.

Expediently, the cutter-type ridge consists of a wire held in a groove of a scoring roller. In this design the cutter-type ridge can be introduced into a scoring roller in a simple manner. Due to the cutter-type ridge consisting of a wire, only a gentle prefolding or indentation of the workpieces to be folded is created, which facilitates folding true to position.

In an apparatus of the second aspect the cutter-type ridge expediently consists of at least one scoring segment. This scoring segment has a position and length which ensure the desired start of the indentation in the end zones of the scored line.

If, according to the method in accordance with the first aspect of the invention, the central bottom folds and the diagonal indentations for the triangular pockets are prescored by means of the apparatus of the second aspect of the invention, opened out bottoms are obtained whose fold lines agree very exactly with the scored lines. In the manufacture of bags it is therefore possible to lay the opened out bottom square with great accuracy. Because of this the outer dimensions of the bottom can be adhered to more exactly, so that overlaps of the bottom halves to compensate inaccuracies can be reduced, and it is possible to save material or paper.

An example of the embodiment of the invention will be explained below with reference to the accompanying drawings, in which:- Fig. 3 Fig. 4 Fig. 1 is a side view of a scoring roller, Fig. 2 is a top view of the scoring roller according to Figure 1, partly in section, is a view of two scoring rollers butting with their counter rollers for forming, in the manufacture of bags, the indentations in a tubular section for the central bottom fold and the triangular pockets, is a tubular section which has been provided with scored lines by the scoring rollers and counter rollers according to Figure 3, Fig. 5 is a schematic perspective representation of a scoring roller cooperating with a counter roller, with a holding device disposed down the line for passing tubular sections in a bottom opening-out station, Fig. Sa is a section through a scoring roller with a counter roller applied thereto, in the zone of the scoring segment and of the wire effecting the diagonal indentation, and Figs. 6 to 8 show the known prescoring, already described, of tubular sections in the manufacture of bags.

As may be seen in Figures 1 and 3, the scoring roller 11 is provided at one end face with only a scoring segment 12 with a short circular arcshaped knife-type cutter 13 which presses short scored lines 15 in the zone of the ends of the subsequent central bottom folds into the flat lying tubular section 14 made of paper, shown in Figure 4. Starting from one side of the scoring segment 12, a cl groove 16, shown in Figure 5a, with an approximately helical course is formed in the shell of the scoring roller 11. In this groove 16 there is held a pressed-in wire 17 which projects above the cylindrical shell of the scoring roller 11 only by a height that is smaller than its radius.

In the manner shown in Figures 3, 5, and 5a, the scoring roller 11 cooperates with a counter roller 18 which is covered with a shell 19 made of an elastic material, for example rubber or an elastic synthetic material. For the shell, it is, for example, possible to use Vulculan (RTM) with a hardness of approximately 80 Shore.

As shown in Figure 5a, the depth of penetration of the wire effecting the scoring, and of the scoring segment 12 provided with a rounded cutter 13, into the elastic shell 19 are chosen in such a way that the passing bag workpiece 14 is provided with only shallow pressed-in scored lines which ensure a clean folding of the opened-out bottoms along the scored lines or between the scored lines at the end sides, without offering an undesirably high resistance to the folding in the opposite direction. The scored lines, pointing in their shape in the opposite direction to the fold, define the fold lines as the bottoms are opened out, in which process the fold lines are drawn very accurately to the scored lines.

The passing of the bag workpieces 14 through a scoring apparatus with the scoring roller 11 and the counter roller 18, and the running in of the bag workpiece 14 into the bottom opening-out station down the line, is schematically shown in Figure 5. In the bottom openingout station, the bag workpiece passes through cooperating holding plates 21, 22, between which there is formed a narrow gap from which there only project the ends of the bag workpieces which are opened out by the usual opening- out tools into the so-called bottom squares. During the opening-out of the ends of the bag workpieces into the bottom squares, the folds are effected, between (i) the starts of the indentations 15, 16 for forming the central bottom folds and (ii) the scored lines 23 for forming the diagonal folds of the triangular pockets. In Figure 5, there may only be seen the scoring tools and holding devices for forming a bottom square at the left-hand end of the passing tubular section 14. Symmetrically to the median plane, the same tools are again arranged in the way shown in Figure 3.

Claims

PATENT CLAIMS

1. A method for forming fold lines in continuously fed flat workpieces, wherein indentations forming the fold lines are pressed into the workpiece with a scoring tool, and the fold lines are marked only in the zones of their ends by scored lines.

2. A method according to claim 1, wherein said workpieces are laid flat tubular sections and the fold lines are prescored lines for the bottoms to be opened out.

3. An apparatus for scoring continuously fed flat workpieces for forming fold lines, comprising a cuttertype ridge rotating on a cylindrical cover shell, which presses the indentation into the workpiece supported on a rotating bearing means consisting of a roller with an elastomeric shell.

4. An apparatus according to claim 3, characterized in that the cuttertype ridge consists of a wire held in a groove of a scoring roller.

5. An apparatus according to claim 3 or 4, for operating the method according to claim 1, wherein the cutter-type ridge consists of at least one scoring segment.

6. Apparatus according to any one of claims 3 to 5, when incorporated in a bag forming machine for forming the fold lines in laid flat tubular sections for bottoms to be opened out in the manufacture of bags.

7. A method of forming fold lines in continuously fed flat workpieces, substantially as hereinbefore described with reference to the accompanying drawing.

C

8. Apparatus for scoring continuously fed flat workpieces, substantially as hereinbefore described with reference to and as illustrated in, the accompanying drawings.