FI58894B - FOERFARANDE FOER FRAMSTAELLNING AV PLASTBEKLAEDD KARTONGBEHAOLLARE - Google Patents

Description

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Patent · och regliteretyrelaen 'AmMcm utlagd och utUkrtfun puwic * r * d 30.01.81 (32) (33) (31) Pyy4 «* y atuelkai» -8 «| M priorltet 28.07.76

Norway-Norway (NO) 762629 (71) Elopak A / S, Box 26U, N-3 ^ 30 Spikkestad, Norway-Norway (NO) (72) Finn Skjelby, Spikkestad, Svein Slungaard, Spikkestad,

Norway-Norway (NO) (7 * 0 Berggren Oy Ab (5I ») Method of manufacturing a plastic-coated cardboard container -Förfarande för framställning av plastbeklädd kartonbehallare

The present invention relates to a method of manufacturing a plastic-coated carton made of a unitary, folded and heat-welded blank having a rectangular base and substantially straight parallel side walls and closed at its upper end by folding the uniform upper strips inwards along the side edges so that between the top strip and below the oblique fold lines, after which the other edge portions of all the top strips are compressed and closed into a four-layer upwardly rising brush, while the corners of the oblique fold lines are selected so that the top strips forming at most small angles with the plane passing through the bottom of the tank, after which the other side of the brush and the upper side of the upper strip on this side are heated by means of warm air and the brush is folded down and pu is crossed against this top strip by means of a cooling rail to secure it to the top strip in a position which holds both top strips down in an upper plane substantially parallel to the bottom of the container.

Such brush containers or housings have a very well-closed top, so that they can be used for liquid substances such as milk, juice, water, etc. and, of course, also for slightly thicker products 2 58894. Brush containers are made by pressing, grooving and stamping rolls containing cardboard webs coated with permanent cotton into flat blanks with grooved fold lines. These blanks are heat welded on the sides and bottom to form an open container which is then filled to a certain level with the desired substance. Finally, the top of the container is closed by folding it mainly into the shape of a ridge roof with an upwardly rising ridge which is heated and closed by squeezing it together between two clamping jaws. However, it is also known to make the fold lines so that the strips forming the "roof" do not form a considerable angle with each other after folding, so that when the brush is folded down a substantially flat top seam is obtained, at least when a second container is placed above the container.

When the container is opened for use, folded to the second end of the inclined surfaces of the back pass, the weld seam tearing open about half the length of the brush, wherein the brush aukirevityn edge of the upper sheet consisting of a single pouring spout, which is very suitable for the liquid or kevytjuoksui-emptying its contents.

Although the top seam of such brush containers can be pressed substantially flat when the containers or housings are immediately stacked on top of each other, the brush usually straightens slightly upward when the top container is removed. Therefore, it is desirable to attach the brush to the second top strip in a position where the top seam remains flat.

In the manufacture of such a container, attaching the brush to the second top strip is not quite simple. First, the milk containers are made of relatively thick cardboard, whereby many layers of the brush make it very rigid and the brush tends to stand up with a relatively high force due to the inherent stiffness of the substance. Therefore, a firm fastening is required, which, however, is difficult to achieve without making it difficult to open the container and at the same time making the brush larger, e.g. so that the brush extends downwards with one side edge or two end portions along the other side surface. This increases the consumption of cardboard.

The object of the invention is therefore to provide a method for producing an improved brush housing of a known type, by means of which method the brush remains securely closed while the consumption of the raw material 3,5894 remains the same and the container can be easily opened.

This is achieved according to the invention as set out in the appended claims.

However, it is difficult to fold the brush down with good results if the brush is seamed in a position where it is at a 90 ° angle to the upper plane. This is due to the tension on the board. Therefore, it is advantageous to weld the brush in a slightly lowered position, e.g. at an angle of about 70 ° to the upper plane. In order to facilitate welding in the desired oblique position and the subsequent lowering of the brush, it is also preferred that the fold line between the upper edge part and the upper strip forming an angle of less than 90 ° with the brush is more strongly grooved than other fold lines and in particular consists of two parallel grooves.

Another prerequisite for achieving a good result is the controlled heating and cooling of the brush to provide adequate welding without adversely affecting the sealing of the container at the brush. This is accomplished by heating with air and pressing the brush down using the cooling rails.

Finally, it is important that the folding is not performed by simply pressing the brush down. Thus, in addition to the cooling rails that press down the brush, compression rails are used on both sides of the brush to press down on the upper strips.

The object of the present invention can thus only be achieved by combining all the features set out in claim 1.

In order to achieve the best possible result, it is still important that the unfolding takes place without twisting the container at an angle. This is easily done on standard milk packaging machines if the brush and top strips on standard chain guides are folded down strongly. Therefore, according to a preferred embodiment of the present invention, a chain guide is used, supplemented by an additional control chain, by means of which the container is guided securely without distortion. Conventional milk container handling machines use two overlapping control chains at 4,5894 at the top of the container, while the lower end of the container is instead supported by only one chain guide on the other side. According to a preferred embodiment of the present invention, the container is instead guided between two superimposed control chains also at the lower end of the container.

The invention will be explained in more detail below with reference to the accompanying drawing.

Figure 1 shows the upper part of a pre-grooved and stamped blank which is pressed into a container according to the invention.

Figure 2 shows a vertical section of the top of a pre-assembled container with a folded brush according to the invention.

Figure 3 shows a vertical section of the top of the container and the clamping jaws during the sealing of the brush and the sealing of the brush in an oblique position.

Figure 4 shows a perspective view of a container according to the invention as it exits the sealing device.

Figure 5 schematically shows a hot air nozzle used in welding to heat the parts of the brush and the upper strip to be connected to each other.

Figure 6 shows a partial section of the hot air nozzle of Figure 5.

Figure 7 is a perspective view of the rails used to lower the brush and top strips to form a flat top seam.

The part of the grooved and stamped plastic-coated cardboard blank 1 shown in Fig. 1 forms the upper part of the non-welded container. In the further processing of the container, the blank 1 is folded by grooving along the weakened vertical fold lines 2 and the edge 3 is heat-welded to the opposite edge part 3 '. The bottom part (not shown) is then folded and heat-welded in a manner known per se with an inner mandrel, the blank 1 forming an open container which can be filled with the desired substance, e.g. milk, up to the fold lines 8 between the container (part B) and the closure strips 4, 5 (parts A). After filling, the solid strips are folded in along the lines 8 so that the strips 5 are folded in under the strips 4 by simultaneously folding along the grooved diagonal lines 7 and the other fold lines 9 and 10 in a manner known per se.

The angle of the slashes 7 is chosen so that both the flat strips 4 and the folded strips 5 remain approximately horizontal when the container 5 58894 is closed. As shown in Fig. 2, the brush is further folded completely down into the upper plane and fixed in this position, whereby the upper seam remains substantially horizontal, since the material specific stiffness tends to raise the upper seam and in particular the brush.

To achieve this, it is preferred that the brush formed by the fields 4 'and 5' be kept at an angle of less than 90 ° to the upper plane during welding and not in its natural vertical position. In practice, an angle of about 70 ° to the upper plane has proved advantageous. This is shown in Figure 4, which shows a container with a pre-folded top and an oblique brush. The folding of the top and the welding of the brush are performed as shown in Fig. 3 by means of clamping jaws 6 and 7, in which the clamping surfaces 6 'and 7' are inclined at the desired angle. The clamping jaws compress the brush together after it has been preheated in a suitable manner, e.g. with hot air. The jaws are cooled and they keep the brush compressed until it has cooled sufficiently.

The fold line 9 located between the upper edge portion 4 'and the rest of the strip 4 against which the brush tilts during welding may preferably be in the form of a double groove line to facilitate folding of the brush.

A brush closed in such an oblique position and / or having such a double groove line can then be folded down against the top of the container without damaging the carton or seam. However, it has been found that holding the brush in this position is not quite simple. The attachment must be strong enough to overcome the considerable force which, due to the inherent stiffness of the material, tends to lift the brush. On the other hand, the fastening must not be so good as to make it difficult to open the container. However, it has been found that the brush can be welded to the strip without damaging the seam of the brush by means of the controlled heating of the brush and the second upper strip. All other welds in the tank are carried out between the immediate jaws or resistors which press the cardboard layers between them, but when welding the brush onto the upper strip 4, it is impossible to obtain a resistance below the upper strip. This makes the welding operation particularly cumbersome, and it is not at all obvious that the brush can be welded to the top strip 4 without heating it so much that the seam of the brush may be damaged. In previously known containers in which an attempt has been made to keep the brush down to smooth the top of the container, the brush is always extended so that the welding point is spaced from the brush seal and preferably located along the container edges, the sidewalls forming a "stiffening ring"

As shown in Figures 5 and 6, a hot air nozzle 11 is used to heat the brush and the adjacent strip 4, which blows hot air through small nozzle openings 12. The nozzle 11 may have a length corresponding to a suitable multiple of the width of the container. The nozzle openings 12 can be arranged so that hot air is applied to the same points of the brush and the strip 4 each time the intermittent tank conveyor is stationary.

After suitable heating for a few seconds with warm air, e.g. about 170 ° C, the containers are further conveyed under the clamping rails 13 and 14 shown in Fig. 7. The function of the middle rail 13 is to depress the brush, while the two rails 14 press the top strips 4 down on both sides of the brush, as best shown in Fig. 8. All three rails have a rounded inlet to provide a gradual depression, and the rail 13 is further bent outward in a horizontal plane, as best seen in Figure 9, with the front located approximately in the biscuit plane of the container, while the main body of the rail 13 is in a vertical plane affects the free end of the brush when it is in the lowered position.

The drawing does not show a guide that holds and moves the containers as they pass under the rails 13 and 14. However, this is an extension of conventional chain guides used in machines for handling such milk containers. Conventional Chain Guides used for this purpose comprise two guide chains on each side of the upper end of the container, while at the lower end of the container there is only one guide chain on the other side of the container against which the container rests. However, according to the invention, this chain guide is supplemented by an additional control chain located immediately above the lowest control chain of the ordinary chain guide. In this way, the container is clamped between two control chains from both the top and the bottom.

This is important so that the tank is not twisted out of position when the brush is folded down and welded into place. Such warping can cause additional stresses to be placed on the weld seam holding the brush down due to return to the normal position when the tank exits the machine.

Claims (2)

58894 7 A method of making a plastic-coated carton made of a unitary, folded and hot-welded blank having a rectangular base and substantially straight side walls and closed at its upper end by folding in uniform sealing and top strips 5 along the side edges so that two opposite edges folded in between the two upper strips (4) and below the oblique fold lines (7), after which the upper edge portions (4 ', 5') of all the closing and upper strips are pressed together and closed into a four-layer upwardly rising brush only a fraction of the distance from the brush parallel to it on the side edges of the container, while the angles of the oblique fold lines (7) are selected so that the upper strips (4), with the exception of their ridge-forming parts (4 '), remain folded and closed in planes forming at most small angles to the bottom of the container with the plane passing through, after which h The other side of the plow and the top of the top strip on this side are heated by warm air and the brush is folded down and pressed against this top strip by a cooling rail to secure it to the top strip in a position holding both top strips down in an upper plane substantially parallel to the bottom of the container in addition to and on either side of the cooling rail, compression rails are used to depress the top strips. A method according to claim 1, characterized in that the container is conveyed during the depressing step in a chain guide of the type common in machines for handling such containers, but supplemented by an additional control chain, whereby the container is guided securely without distortion. Method according to Claim 1 or 2, characterized in that the brush is welded in a manner known per se to a position in which it forms an angle of less than 90 ° with the upper strip against which it must subsequently be folded down.