GB2032293A

GB2032293A - Process and apparatus for making filter bags

Info

Publication number: GB2032293A
Application number: GB7931902A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-09-21
Filing date: 1979-09-14
Publication date: 1980-05-08
Also published as: IT7925813A0; FR2436673A1; DE2929194A1; LU81696A1; GB2032293B; BE878915A; FI792457A7; SE7907759L; NL7906264A; IT1123213B; DK377879A; NO792907L

Abstract

A process for making filter bags comprises forming a flat tube (20) from a paper web by folding both longitudinal edges (5) inwardly so that they overlap at (55) in a central region of the web and forming two rows of filter bags (21) from the flat tube with each bag having one edge (12) formed as a line where the paper is folded. Each bag also has two sealed edges (10 and 11) and an open curved edge (15). The apparatus for practising the process comprises means for joining the longitudinal web edges together by embossing to form a flat tube, means for joining portions of the web together to form the edges (10, 11) and means for cutting the edges (10, 11, 15) of the filter bags such that only the hatched areas of the tube go to waste. The bag may be used as a coffee filter bag. <IMAGE>

Description

SPECIFICATION Process of and apparatus for making filter bags and filter bags made therewith This invention relates to a process of and apparatus for the manufacture of filter bags as weil as to the filter bags themselves.

Filter bags used in making coffee often have, when laid flat, an outline similar to a trapezoid, the opening of the bag being at the long, in most cases, curved base edge of the trapezoid. The two paper layers, superposed in the flat state, of such a filter bag can be integrally connected along one trapezoid arm at a line where the paper is folded; compared with filter bags the paper webs of which are joined by embossing on three sides, this has the advantage that they are less likely to collapse when used and contain less paper.

Filter bags of the folded type can be manufactured by punching corresponding cut-outs, folding them individually and joining the superposed paper layers on two edges; this is a very involved process. They can also be manufactured, however, by longitudinallyfolding a paper web, joining the superposed paper layers along the particular edges of the future filter bags and cutting out the filter bags. Although this can be simpler, as previously practised, it can lead to more paper waste.

It is an object of the invention to simplify the manufacture of filter bags and, in particular, to enable the filter bags to be manufactured economically and with saving as much paper as possible.

According to the invention there is provided a process for the manufacture of filter bags, wherein a web of filter paper is folded into the shape of a lay-flat paper tube which is then converted into filter bags by locally joining, and cutting, its superposed layers.

A further aspect of the invention provides apparatus for the manufacture of filter bags comprising means for advancing filter paper in the form of a web, means for forming the web into a lay-flat paper tube, means for joining superposed paper web layers of the tube at locations to form edges of the filter bags being formed and means for cutting out the filter bags.

Yet another aspect of the invention provides a filter bag which, when laid flat, has two paper layers with an outline similar to a trapezoid, superposed one on the other and integrally connected to one another along one trapezoid side, one of the paper layers consisting of two paper parts joined at an overlap line which intersects the opening edge of the bag and another trapesoid side of the flat outline of the bag.

The lay-flat paper tube has the advantage that it can readily be worked. Moreover, when it is made with folded longitudinal edges, it makes it possible, in its edge zones, to manufacture filter bags which have a folded edge on a trapezoid side. If, in the preferred manner, only two interlocking rows of filter bags pointing in opposite directions are manufactured the waste can be restricted to a minimum, only filter bags of the preferred folded type being manufactured. If the filter bags of the two rows are to have approximately the same appearance, the junction of the edges of the paper web is located, in the preferred manner, approximately in the centre of the longitudinal zone of the lay-flat paper tube.

The invention will be discussed in more detail, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a side view of essential components, with frame omitted, of apparatus embodying the invention; Figure 2 is a plan view of the components of the apparatus shown in Figure 1; Figure 3 is a simplified sectional view, enlarged relative to Figure 1 and taken along line Ill-Ill in Figure 1; Figure 4 is a perspective view of a detail of the apparatus; Figure 5 is a plan view of part of a lay-flat tube showing the arrangement of filter bags to be produced therefrom and drawn to a scale which differs from the scale of eac of the preceding Figures; and Figure 6 is a view of the opening side of a slightly opened filter bag.

Referring to the drawings, a roll 1 of filter paper is shown rotatably mounted in a frame which is not shown. From there, the web 2 of filter paper is drawn through the apparatus. Suitably the drawing force can be generated by the action of a pair of embossing rollers 3. The paper web 2 first passes a bending device illustrated as two folding rods 4 which act to lay the two longitudinal edges 5 of the web inwardly.

Guide rollers 6 interact with a hollow guide body 7 to cause the longitudinal edges 5 of the web to be superposed in the manner which can be seen from Figures 2 and 5.

The overlapping edges 5 of the web now pass the pair 8 of the embossing rollers 80 and 81 to cause formation of a tube 20 of the filter paper. The rollers 80 and 81 are mounted on parallel axes 32,83. The axis 82 is mounted, in a manner which is not shown, on the machine frame which is not illustrated. The axis 83 is connected to the axis 82 by a swan neck arrangement 84, which can readly be seen in Figure 4, so that the edges 5 of the web can be fed to the embossing rollers 80,81, one edge passing through the slot 85 and the other passing the location 86.

The tube 20 thus formed is then laid flat by a metal sheet 9, projecting from the guide body 7 and gradually widening, and enters between the embossing rollers 3 which carry out local embossings which correspond to the edges 10 and 11 of the filter bags 21, as shown in Figure 5, whereupon a pair of cooperating cutting rollers 30 cut out the filter bags 21. In the lay-flat state, these filter bags have an outline similar to a trapezoid, of which one trapezoid arm 10 and the smaller base 11 have paper layers 13, 14 (Figure 6) which are joined by embossing. Along the trapezoid arm 12, (Figures 6 and 5) which coincides with the edge 120 of the tube (Figure 5), the paper layers 13,14 are integrally joined to one another on a folding line. These are thus filter bags 21 which are folded along the trapezoid arni 12. The junction 55 (Figures 2,5 and 6) of the longitudinal edges 5 of the paper web 2 intersects the opening edge 15 (Figure 5) and the embossed trapezoid arm 10 of the filter bag 21.

Due to the arrangement of the filter bags 21, resulting from Figure 5, the waste indicated by horizontal hatching can be restricted tio a minimum, although the filter bags 21 are cut with a curved opening edge 15.

A station 22 serves for collecting the filter bags 21 and, if appropriate, packaging them; this can be carried out in a manner which is in itself known.

Claims

1. A process for the manufacture of filter bags, wherein a web of filter paper is folded into the shape of a lay-flat paper tube which is then converted into filter bags by locally joining, and cutting, its superposed layers.

2. A process according to claim 1, wherein the paper tube is formed by running together and joining the longitudinal edges of the paper web.

3. A process according to claim 2, wherein the junction of the longitudinal edges of the paper web is located in the central longitudinal zone of the lay-flat paper tube and two interfitting rows of filter bags are formed which in the flat state are similarto a trapezoid with each filter bag being given an uncut trapezoid side consisting of a longitudinal edge of the lay-flat paper tube the filter bags in the different rows being oppositely orientated.

4. A process according to claim 1,2 or 3, wherein the joining of superposed layers of the paper web is effected by embossing.

5. Apparatus for the manufacture of filter bags comprising means for advancing filter paper in the form of a web, means for forming the web into a lay-flat paper tube, means for joining superposed paper web layers of the tube at locations to form edges of the filter bags being formed and means for cutting out the filter bags.

6. Apparatus according to claim 5, which comprises a guide device for laying the longitudinal edges of the paper web inwards and superposing them, a guide body, joining means forjoining the superposed longitudinal edges of the paper web and means for laying flat the paper tube so formed.

7. Apparatus according to claim 6, wherein embossing rollers are provided as the joining means for joining together the superposed longitudinal edges of the paper web.

8. Apparatus according to claim 7, wherein the embossing rollers are connected to one another by a swan neck arrangement, one embossing roller being located in the interior of the guide body.

9. Afilter bag which, when laid flat, has two paper layers with an outline similar to a trapezoid, superposed one on the other and integrally connected to one another along one trapezoid side, one of the paper layers consisting of two paper parts joined at an overlap line which intersects the opening edge of the bag and another trapezoid side of the flat outline of the bag.

10. A filter bag according to claim 9, wherein the overlap line has been joined by embossing as have the layers at said other trapezoid side of the bag.

11. A process of making filter bags substantially as herein described with reference to the accompanying drawings.

12. Apparatus for the manufacture of filter bags constructed and arranged to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.

13. A filter bag when made by the process of any one of claims 1 to 4 and 11 or using the apparatus of anyone of claims 5 to 8 and 12.