METHOD OF MANUFACTURING FILTER BAGS AND A FILTER BAG

Abstract: The present invention relates to a method of manufacturing filter bags and a filter bag. In a method according to the invention two sheets of filter material are superimposed, the superimposed paper sheet layers are then joined together along the seams of the bags, defining two or more rows, immediately bordering on each other, of immediately adjacent trapezium-shaped filter bags, positioned opposite to each other, the edges of which form a sine-wave-like figure when the filter bags are cut apart. Thus the loss of material can be considerably reduced.

Description: METHOD OF MANUFACTURING FILTER BAGS AND A FILTER BAG The present invention relates to a method of manufacturing filter bags and a filter bag or pouch. These bags or pouches are specially used for making of filtered coffee. A problem in previous methods of manufacturing filter bags has been the great amount of process waste. The per- centage loss of filter material can be as high as 40%. The object of the present invention is to considerably reduce the loss of material and thus reduce manuf cturing costs. This is achieved with a new cutting pattern and a new shape of the filter bag. In a method according to the present invention, two sheets of filter material are placed on top of each other, the superimposed paper sheet layers are then joined together along the seams of the filter bags, defining two or more rows that immediately border on each other, of immediately adjacent trapezium-shaped filter bag blanks, positioned opposite to each other, the edges of which form a sine- wavelike or otherwise undulating pattern when the filter bags are cut apart. A filter bag according to the present invention comprises two superimposed layers of paper, joined together at the curved bottom and the straight edges and essentially shaped like a trapezium, but the upper edge of which is wavelike and the bottom correspondingly curved. What is achieved with the new cutting pattern and shape of the filter bag according to the invention is that there will be no loose slips between the filter bag blanks and thus the loss of material is kept to a minimum. According to the preferred embodiment of the invention the cutting pattern is sinusoidal. The invention is, however, by no means limited to only this cutting pattern, but any other waveform is also possible, by means of which the object of this invention can be achieved. According to one embodiment of the present invention, the desired pattern can be embossed into one or both of the filter material sheets before joining the sheets together. Thus a filter bag according to the invention can inside it have embossed, for example, a scale for measuring the correct amount of coffee or an emblem of the manufacturer. In a method according to the invention the filter material is supplied from two rolls of paper, the width of which is preferably about 1 meter. The great width enables a larger production volume than previous methods. Less machinery and therefore less personnel is reguired to obtain large production volumes, which together with a smaller loss of material reduces production costs. The present invention is described in closer detail by referring to the enclosed schematic figures, in which: FIGURE 1 is a side view of the apparatus for carrying out the method according to the invention FIGURE 2 is the apparatus in FIGURE 1 as seen from above FIGURE 3 represents a filter bag according to the invention The filter paper sheet is supplied from two rolls 1 and 2 of paper. A measuring scale, an emblem of the manufacturer or another desired text 22 is embossed into one of the sheets 3 with the apparatus 5. The sheets 3 and 4 are then superimposed in a way disclosed in prior art and joined together along the straight side seams 10 and 12 and the curved bottom seam 11 of the filter bags by crimping roller 6, thus defining filter bag rows 21, immediately bordering on each other. The neighbouring rows share a common dividing line between them, formed in turn by the top edge 15 and in turn by the bottom edge 16 of the neighbouring filter bags, positioned opposite to each other. After that a roll cutter 7 cuts off the filter bags 20 from their curved top 15 and bottom 16 edges in a sine-wavelike form, and from the straight edges 13 and 14. After the cutting the filter bags are sorted 8 into "right hand" and "left hand" groups for subsequent inspection and packing. The straight edges 13 and 14 of the bag 20 can be perfora¬ ted instead of cut, thus obtaining rows 21 of filter bags attached to each other at their straight edges, and from which a bag can be torn off. This could be a preferable solution for those consuming large amounts of filter bags. The filter bags can also be perforated differently in order to obtain different groups of filter bags. When utilizing a method according to the invention, no loose slips are defined between the filter bag blanks, e.g. there is only a minimal amount of process waste, as is clearly disclosed in Figure 2. Only between the edges of the outermost rows and the edges of the paper sheet will some waste material be formed. When producing usual sizes of filter bags, the material loss is only 4-5 %. A filter bag 20 according to the invention (FIG. 3), having a preferable shape, comprises two superimposed layers 17 and 18 of paper. The layers are joined together from the bottom 16 and the straight edges 13 and 14 with seams 10, 11 and 12. The wave-like top edge 15 is open. A measuring scale 22 has been embossed into the filter bag.

Claims: Claims : 1. A method of manufacturing filter bags, characterized in that two sheets of filter material (3, 4) are superim- posed, the superimposed paper sheet layers are then joined together along the seams (10, 11, 12) of the filter bags thus defining two or more rows (21) that immediately border on each other, of immediately adjacent trapezium-shaped filter bag blanks, positioned opposite to each other, and that when the filter bags (20) are cut apart, the edges of the rows form a sine-wave-like or otherwise undulating pattern. 2. A method as recited in claim 1, characterized in that the desired pattern (22) is embossed into one or both of the paper sheets (3, 4). 3. A filter bag, characterized in that it comprises two superimposed layers of paper (17, 18), essentially trape- zium-shaped, the top edge (15) of which is wave-like and the bottom (16) correspondingly curved, and the layers being joined together at the sides (13, 14) of the trapezium and at the curved bottom (16). 4. A filter bag as recited in claim 3, characterized in that either the out- or inside of the bag is provided with a desired pattern, e.g. a scale for measuring coffee or an emblem of the manufacturer.

Inventors: MARS VESA, MARS, VESA
Applicants: AHLSTROEM CONSUMER PROD, AHLSTROEM KULUTTAJATUOTTEET OY
Application year: 1991
Main classification: A47J31
IPC codes: A47J31, B01D39, B31B25