Method of forming a package from a strip of material

IS 2 280 342 T3

DESCRIPTION

Method of forming a package from a strip of material.

Background of the invention

Strips of material are used to make diapers and other absorbent products. The strips are cut on the manufacturing line, on longitudinally spaced cross-cut lines to divide the strip into individual webs each used in the manufacture of a respective absorbent product. In general, these strips are also die-cut to provide different heights, in order to outline the products to better fit the user's body, and to improve aesthetics. Most of the current processes of this type, punch the elements from a single strip of material, which has a width at least equal to the maximum width required, and discard the waste from the sides, formed by cutting the side parts to the scalloped width, narrower. Attempts have been made to recycle scrap parts, generally by shredding and returning the materials to the strip manufacturer. However, recent developments have increased the complexity of the materials, thus increasing the cost and making recycling more difficult. Therefore, there is an interest in reducing the amount of waste.

Previously, it has been proposed to longitudinally slit a web of the required materials into a plurality of juxtaposed strips having variable widths. Shaping is carried out so that the strips have the widest part of one, adjacent to the widest part of the next, and vice versa. This eliminates, or at least reduces, the amount of scrap, relative to an arrangement in which all the webs are individually cut from a respective constant width strip.

However, the packaging of such continuous strips is problematic, since the strip elements are of varying width, so that the location at the side edges varies. One purpose is to form the strip into a single roll or notebook, which is spirally wound. Another purpose is to roll the strip into a cross bundle. Neither package structure is stable, since the side edges of one rolled layer do not directly overlap the side edges of the next, leaving protruding parts and raised edges.

Previously, pre-bundles of a continuous strip of material have been formed using a technique known as "scalloping", in which the strip is folded back and forth to deposit a series of strip parts back and forth, with each part being folded relative to the next, around a line transverse to the strip. The scalloping technique has been available for many years, and is used to package many different types of materials, but especially material of a fibrous nature such as cloth, non-woven strips, and the like. In this technique, conventionally the strip is guided into a receptacle such as a cardboard box, while a first rocking motion causes parts of the strip to be deposited through the receptacle, and folded back and forth, and a second rocking motion causes the positions of the parts intersect in relation to the receptacle, transversely to the parts. Typically, the receptacle comprises a rigid rectangular container, at least partially made of cardboard, having a base and four vertical sides.

Scalloping can be used to package the strips of variable width, but this technique has significant disadvantages, which inhibit the effectiveness of the product when it is removed and processed. In particular the crease lines, which are essential to the process, will interfere with the absorbency or other characteristic of the material, when such crease lines occur in a central area of ​​the web.

US-A-5 956 926 discloses a method according to the preamble of the claim. Summary of the invention

The object of the present invention is to provide an improved method of forming a package from a strip of material.

In accordance with the aspect of the invention, there is provided a method of forming a pack from a strip of material, comprising the features set forth in claim 1.

Preferred features are described in the dependent claims.

Brief description of the drawings

An embodiment of the invention, and some examples that are not part of the invention, will now be described in connection with the accompanying drawings, in which:

Figure 1 is a schematic, isometric view of a continuous strip package (not part of the present invention), the package including a plurality of strip layers, and shown with flexible packaging material omitted, for convenience in illustration;

Figure 2 is a top plan view of the package of Figure 1 with the flexible packaging material, included;

Figure 3 is an end elevation view of an apparatus and method for forming the package of Figure 1;

Figure 4 is a top plan view of the apparatus of Figure 5;

Figure 5 is a top plan view of the platform of the apparatus of Figure 4, showing the strips in an extended arrangement for juxtaposition folding;

Figure 6 is a top plan view of a package structure formed using the method of the invention;

Figure 7 is an isometric view, of a package of the type according to Figure 6, showing the spliced ​​connections of each strip with the next, but for convenience in the illustration the strips are shown with constant width;

Figure 8 is a schematic side elevation view of a manufacturing line for cutting the strip into sheets; and Figure 9 is a top plan view of the line of Figure 8.

In the drawings, like reference characters indicate corresponding parts in the different drawings.

Detailed description

As shown in Figures 1 and 2, the package comprises a generally rectangular body 10, formed from a strip 11 of a material to be packaged, and generally this material will be fibrous in nature, formed from a woven or woven material.

ES 2 280 342 T3 non-woven, although this is not essential to the structure of the package. Many materials of various thicknesses can be packaged using the scallop technique, as long as they can accept the necessary crease at the end of each part.

The body of the package is formed of a plurality of juxtaposed stacks of strips, where each stack comprises a plurality of folded strip portions of the strip that are deposited on top of each other. Thus, as shown in figure 1, the parts are folded back and forth, in respective extreme fold lines 25 and 16, so that the fold lines lie in a common vertical plane defined by the ends 15 and 16 of the stack. . Each part of the strip lies directly on the previous part, so that the lateral edges 27 and 28 of the parts of the strip define a first set of lines in the common plane, at right angles with respect to the strip parts that contain all side edges 27 of the stack and similarly the side edges 28 of the stack strips define a second set of lines in the common plane, at right angles to the strip portions containing all the side edges 28 of the stack.

Thus, the pack is formed by stacking the parts each one on top of the next, from a lower part 29 to an upper part 30, to form the stack. Thus, the package is formed from the plurality of stacks 12, each of which has a length equal to that of the other stacks, and therefore equal to that of the package, and the stacks are formed to a common height. which, therefore, is equal to the height of the package. Package 10 is formed from a plurality of individual stacks 12 arranged in juxtaposition. In figure 1 only three such stacks are shown, for convenience in illustration, while in figure 2 six such stacks are shown arranged in juxtaposition, forming a complete package structure. Each stack is formed from a folded strip, which is continuous through the stack. Each stack has an upper end 13, a lower end 14, two ends 15 and 16 that are in opposition, and two sides 17 and 18 that are in opposition.

Of course, it will be appreciated that the dimensions of the package can be varied according to need, so that the number of stacks can be increased or decreased, the length and height of each stack can be varied to increase the number of folded strip parts, and to increase the length of the folded strip parts.

As best seen in the plan view of the strips of Figure 2, the strips in each stack are folded back and forth from the fold lines 25 to the fold lines 26, to form a folded strip portion having a length equal to the distance between the fold lines.

As described below, the strips are cut to have a variable width between the side edges 27 and 28 of the strip. In the example shown, the strips are a simple shape in which the width varies periodically between narrow sections 32 and wider sections 33: In other examples more complex width variations can be used.

In the example shown, the strip is intended for the manufacture of diapers, or similar products that are each formed from a respective web cut from the length of the strip.

Each web element in the example shown has a planned cut line 34 in the widest section 33, and a cut line 35 also foreseen in the widest section 33, so that the narrower section 32 is located between the lines. planned cut-off.

It will be appreciated that in the package structure shown, there has not yet been any cutting of the strips in the transverse direction, and the cut lines 34 and 35 are in fact imaginary lines. However, its position can be determined by the design of the webs, and the position along the length of the strip that forms the beginning and end of the webs. The laminar elements are, in fact, thus arranged end-to-end, so that each one is separated from the next, simply by cutting along the intended cutting line.

The strip has a variable characteristic along its length, which determines the position of the laminar elements in the strip, and therefore ends the positions of the intended cutting lines. In the example shown, the variable characteristic is the variable width. Other features such as additional materials or variable thicknesses can be used.

Therefore, from Figure 2 it will be noted that each part of the folded strip, of each of the bodies of the package, is defined by an exact total number of laminar elements. In the example shown, the number of laminar elements is three, but of course this can be varied, from a minimum of one to a maximum that depends exclusively on the maximum acceptable size in the structure of the transportable package. In most cases, it is preferred that the folded strip portion contains more than one web, since frequently the webs are on the order of six inches (15.2 cm) to two feet (61 cm) in length, and the required package structure will generally be significantly greater than this, and certainly on the order of four feet (122 cm).

In the example shown, the design of the wider and narrower parts of the strip is arranged so that no debris is generated when the slitting action occurs, and the wider parts exactly match the narrower parts of the strip. the following strips. However, in some cases there may not be an exact fit between the widest parts of the strip and the narrowest parts of the next adjacent strip, so some scrap will be generated when trimming the frame and discarding such scrap parts.

Thus, as shown in Figure 2 the strip parts will each nest exactly next to the next, with the narrower parts of one receiving the wider parts of the next. In a situation where the wider parts do not exactly match the narrower parts, there will be some nesting effect, even though there may be gaps between the folded strip parts.

The fact that each folded strip part contains an exact total number of strip elements ensures that the cut lines occur directly at the fold lines. Thus, there are no fold lines through the strip anywhere in the webs, after the webs are cut along the cut lines. This is desirable since the absence of fold lines

ES 2 280 342 T3 in the material of the laminar elements, it will avoid compromising the absorbency performance of the laminar element in the main body of the laminar element.

Furthermore, the fact that the folded strip part contains a total number of laminar elements, and that the laminar elements are identical, ensures that the side edges of each folded strip part lie directly on the side edges of the strip parts. folded previously deposited. Therefore, there are no protruding or raised strip parts, and all strip parts are completely contained within the stack. Therefore, the pile is in fact a solid structure that has a constant density across its width. Therefore the stack, when compressed, can form a very rigid structure without the possibility of damaging the lateral edges of the strip, or of sandwiching some material between the lateral edges of the strip.

In the examples shown in figure 2, to provide the nesting effect, because all of the package bodies are in fact identical, with the fold lines arranged through the widest parts of the strip, it is necessary displacing each stack relative to the next, in a longitudinal direction of the strip. This is in contrast to the essence of the invention. Thus, each stack is displaced by half the length of the web. Thus, for example, the fold line 25A of the laminar element 12A is displaced with respect to the line 25 of the laminar element 12, by a distance equal to half the length of the laminar element, from the fold line 25A to the cut line 34. However, the nesting effect of the stack provides an integral package structure, when the stack is gathered and rolled up by the packaging material, as described below.

As shown in Figure 6, an arrangement can be provided with the method of the invention in which the position of the fold lines relative to the laminar elements is of minor importance and it is possible to accept a fold line 35A, in a position along the length of the web different from the intended cut line 35. Thus, there is no need to move the stacks longitudinally, since the fold lines 35A in alternate stacks are arranged in the narrower parts 32 of the strip. Thus, the fold lines are aligned, but the webs are longitudinally offset. In such a way, the package structure can be directly rectangular, apart from the outer edges which are profiled to follow the side edges of the outermost package bodies.

The package is rolled up by means of a flexible packaging material, preferably non-permeable heat seal plastic, which encompasses the entire package indicated at 40 (not shown in Figure 1). The packaging material forms a sealed package that allows air to be drawn from the package, and this vacuum action can be used with physical compression D from the top and from the bottom 13 and 14 of the package, to compress the package to a reduced height, in a vacuum packaging system. The amount of compression can be determined to minimize the volume of the package, without interfering with the required thickness of the product when it is removed from the package. Thus, the package structure avoids the need for rigid sides, a box or similar container, so that the package structure is stable, due to compression of the layers to reduce the height of the layers, and due to to the pressure of each layer against the sides of the next adjacent layers.

Compression of the package is possible only in direction D, which is at right angles to the surfaces of the strip parts. This acts to compress the height of the stacks, so that the thickness of each strip portion in the D direction is reduced by such compression. Compression along the parts, or at right angles to the piles, is not possible since it will act to deform the strip. Therefore, mechanical compression of the package in the D direction thus reduces the dimension of the package in that direction, allowing air to be drawn from the flexible packaging material 40, causing the material to be pulled down onto the pack, to keep it in its compressed condition and to apply pressures that tend to hold the stacks in close contact.

The strip of each layer is connected to the next, by a crossed or spliced ​​portion of the strip, which extends from one stack to the next, to form a continuous strip through the entire length of the package. The technique for connecting the strip from each stack to the next layer is shown in Figure 7. In Figures 1 to 6, the spliced ​​portion is simply omitted for convenience in the illustration. Thus, in Figure 7 four stacks 200, 201, 202 and 203 are shown. The strip of each pack is continuous, from an upper strip portion 205 to a lower strip portion 206. The connection is made by a tail portion 208, which extends from the lower portion 206 beyond an end of the battery. The portion 208 extends along the end of the stack at 216, and includes a turn 215 with fold lines 213 and 214, to form a portion 217 that extends along the end of the next adjacent stack. The portion 217 is connected, via a junction 211, to the top 205 of the next adjacent stack. Other splice arrangements are possible.

Turning now to Figures 3, 4 and 5, a technique for forming the package structure is shown in greater detail. A web 50 is provided on a master roll 51, and is unwound from the master roll by a feed and guide system 52, which includes two pairs of pressure rollers 53 and 54. A slitting system 55 is mounted, transversely to the band, to divide the band into a plurality of juxtaposed parallel strips. This may be provided by a slitter bar, carrying a plurality of slitting blades in transversely spaced positions, to longitudinally cut the web into a plurality of strips 57 which are each conveyed forward by guide system 52, of shape that they stay in the common plane of the band, and they stay edge to edge. However, preferably the slitting system comprises a die roll 56, over a pressure roll 56A to cut the strips into the widest and narrowest parts, described above.

To form the package structure shown in Figures 1 and 2, where the fold lines are arranged in the widest parts of the strip, it is necessary to spread the strips apart to adopt the

The position shown in Figure 5, and also longitudinally offset the strips so that the wider portions 33 are aligned across the strip, and the narrower portions 32 are also aligned across the strip. This movement takes place in an area generally indicated 90, which occurs between rollers 54 and a guide roller 58. In this area 90, the strips 57 are split apart by means of a suitable guide system, well known to those skilled in the art, and alternate strips are passed over a deflection roller 91, which increases the length of the path by a distance equal to half the length of a web, so that when the strips pass through guide rollers 58 they are aligned in the position shown in Figure 5.

The strips 57 are supplied on a guide roll 58, in a fold system indicated generally at 59, located below the feed roll 58. The fold system 59 comprises a support table 60, which has a width sufficient to receive the entire width of the band 50, when extended as shown in Figure 5, ie the strips in juxtaposition. The support table 60 is of sufficient length to receive the parts of the strips deployed in the frame, as previously described. The table 60 is mounted on a lifting system 61, shown only schematically, and acts to raise and lower the table, such that the table is gradually lowered as the strips are folded over the table.

The folding system further includes a pair of fold bars 62 and 63, which act to fold the strips back and forth across table 60. Fold bar 62 is mounted on an actuator cylinder 64, and similarly the Fold bar 63 is mounted on an actuator cylinder 65. In FIG. 3, fold bar 63 is shown in the retracted position, and fold bar 62 is shown in the extended position. The folding bars are alternately moved between these positions, so that first the folding bar 62 is retracted, and then the folding bar 63 is extended, to move the strips across the table to form the covering parts. strip, previously described. The fold bars 62 and 63 extend across the entire width of the web, to simultaneously engage all of the strips, and to simultaneously move such strips to the folded positions. Thus, the strips remain in the position described above when they are being folded. The folding bars 62 and 63 can be in the form of rollers, to allow the material to pass over the bar without friction, while the material is being pushed by the bar to the required position on the table. The mounting system for supporting the cylinders is not shown, for convenience in illustration, and of course this will be apparent to a person skilled in the art.

The folding system further includes a pair of folding jaws 66 and 67 each disposed at the end of the path of a respective one of the folding bars. The folding jaws further extend across the entire width of the web, and comprise a pair of jaw elements 68 and 69, which can be moved between an open position indicated on the left, and a closed position indicated on the right. The jaws are moved between these positions by an actuator cylinder 70, synchronized in relation to the operation of cylinder 64 and 65. In addition to the opening and closing movement, the folding jaws also move in and out, in a horizontal direction relative to the table, so that they release each fold or fold line after it has been formed, to allow that the cape and the crease at the end of the cape, be thrown over the previous layers, and to move down with the table 60. As illustrated, the folding jaw 66 at the end of the folding, moves outward away from the fold or fold line, and at the same time opens slightly to release the fold between the two parts, to the effect that it falls. down on the underlying parts. The jaws are then opened and retracted inward, ready to receive the portion of the strips wrapped around the folding bar, and to grasp them when they are released from the folding bar, as shown in the folding jaw 67 of the figure. 5. This compound movement can be effected by any suitable mechanical joint, activated by actuator cylinder 70, this arrangement also being self-evident to a person skilled in the art.

Thus the strips are simultaneously deposited in folded parts back and forth, one on top of the other, to simultaneously form a plurality of stacks of the package structure. Thus, each stack is made up of only one of the respective strips. The strip is continuous through the entire stack. To provide a continuous strip, one or more rolls may be spliced ​​at the supply, the splice being formed across the width of the strip, such that each longitudinally cut strip also intervenes for longitudinal cutting through the splice.

The folding of the strips back and forth, in the piles, continues until enough parts are applied in the pile, to complete the pile according to the required dimensions of the pile.

A modified method that is not part of the invention, to manufacture the package of the structure as shown in Figures 1 and 2, basically uses the steps shown in Figures 3, 4 and 5, but instead of using the system slitter 55, using the cutting method shown and described, for example, in US-5956 926, in which a folded web is cut using a web knife through the folded structure. Such an arrangement will form a package structure, in which the individual package bodies are fully nested with the fold lines aligned, so that it is not possible to manufacture such a structure in which the fold lines are all located on the fold lines. Planned cutting of the laminar elements.

In another modified method of package manufacturing, which is also not part of the invention, each individual strip separated from slitting system 55 can be transported to an individual folding head, where the strip is folded back and forth as shown. previously described, to form individual package bodies. When individual package bodies are thus formed, these can be assembled and stacked on a suitable collection platform, for subsequent compression and winding, as previously described.

There is a marker 56B located next to the fold system 59, to apply a readable mark 56C to

ES 2 280 342 T3 machine on the strip, in line with the cutting lines provided to divide each laminar element with respect to the next. The markings shown as a line of dots and dashes in Figures 2 and 6, may comprise an inkjet marking, possibly in the shape of a dot or a square, visible to both the eye and the machine, or in some cases only for the machine. The mark may or may not be located directly on the cutting line, depending on the location of the machine's reader in relation to the cutting blade and, in the example shown, the mark is in a forward location with respect to the line. expected cut. The mark may extend across only a short part, the width of the strip. It will be appreciated that when the marks are registered with the respective cut lines, each mark is offset from its associated cut line by the same distance. In an arrangement where only the fold lines are marked by the ink jet marking, there will only be one marking on each part of the strip. In an arrangement in which the number of laminar elements in each strip part is an integer greater than one, each intended cutting line can be marked, and thus open a plurality of marks on each strip part.

Turning now to Figures 8 and 9, the cut and unfold line for utilizing the strip, and separating the strip into the separate webs, is shown schematically. Thus, the package is indicated at 10 and the strip is withdrawn from the package on a guide element 80, to be directed to an operation line 81. A cutting device 82 is activated by a control unit 83, which receives registration information from marks 56C, when read by a reader 84. Thus, the marks are located in a position to activate the control device, in order to cut on the intended cutting line.

As previously explained, some of the cut lines are located on the fold lines. Depending on tolerances, the cut may not be made directly on the fold line, but may deviate from it slightly. Since it is often envisaged that the webs are longitudinally cut, or otherwise shaped into a final product, with the edges of the web thus being formed into edges of the final product, the cutting line may deviate from the line of fold in a small amount, as long as the fold line does not end in a central area 85 of the final product, indicated by the striped lines 86, 87. That is, the fold lines are arranged close enough to one end of the laminar elements, to avoid compromising the characteristics of the laminar elements.