DE69013902T2 - Pallet load wrapped with stretch film and method and device for its manufacture. - Google Patents

Abstract

Disclosed are palletized loads (2) formed by a plurality of packages (21) and wrapped in stretchable film (1) as well as a related process and apparatus to produce such palletized loads (2). The stretchable film (1) has strengthened sections (111, 112, 113, 211, 212) generated by folded or rolled edges (11, 12) or folded central parts and, where said film (1) connects the load (2) to the pallet (3), it has a roped lower edge (115). <IMAGE>

Description

Technical area

This invention relates to cargo formed from a plurality of units, wrapped in stretchable film and anchored to a pallet, as well as the method and apparatus for producing such packages.

In particular, the invention relates to stretchable film with folded or rolled edges which spirals around a load, combined with the fixing of the load to a pallet by making the lower edge of the film, where it goes around the pallet, rope-like, thereby increasing the stability of the entire packaging, while reducing material consumption and the duration of the wrapping operation and at the same time improving the handling of the palletized load.

State of the art

There are many different packaging materials available for loads consisting of a plurality of units standing on a pallet. A widely used type of packaging material is a stretch film wrapped around the load and pallet. Loads wrapped in stretch film, as well as methods for achieving this and a variety of machines capable of carrying out such methods, are well known in the art, but until now, stability problems of the complete package have often been solved by using separate material, such as cardboard corner packing aids and extra layers of stretch film itself.

The principle of stretch wrapping is that a stretchable film is guided around a load in a spiral configuration by a roll-off and stretching station through relative rotation between a load and the film supply. In one design, the load is supported on a table which rotates around a vertical axis and thereby winds the film around the load. At the same time, the film supply moves along a vertical path so that a wrapping spiral is created around the load. The vertical path of the film normally starts at one end of the load, top or bottom, moves to the other end of the load and returns to the starting point to allow the next load to be wrapped in the same way. Together, the rotation and vertical travel up and down produce double layers of film with opposite spiral direction. However, more than two layers or wide overlaps are often required, particularly to secure the load to a pallet, to ensure sufficient stability of the package. Good examples of such wrapping, methods and devices are contained for example in US patent 3,863,425, GB patent GB 2,063,809, German patent DE-2 724 100 or European patents EP-A 306 573 and EP-A 22 135.

Another method of attachment is to have a stationary load and to rotate the entire unrolling and stretching device around the load. This alternative application is often called a satellite application and is particularly useful when rotating the load causes problems or is impossible. Descriptions of this and similar alternatives are disclosed in DE 3 414 964, US application 411 995 or EP-A 279 871 and are widely used in the industry.

Further improvements in the technical field that have been disclosed are all based on these two basic stretch wrap applications. However, they all suffer from the disadvantage of high film consumption and often require packaging aids to provide the required stability.

Developments towards more economical use of the film are described in US Patent 4,497,159 and GB Patent 2 083 002 by increasing the stretch of the film and thus reducing the amount of film per package.

Similar developments have been made allowing the use of different types of stretch film material. US Patent US-4,432,185 describes bundling the front and rear ends of a non-self-adhesive stretch film into a rope to facilitate fixing the rear end to the front end of the film. EP-A 32 140 describes an improvement for fixing the front end of the stretch film by controlled wrapping over the front end of the film with successive layers of stretch wrap.

US Patent 4,807,427 describes a rope-like formation of stretch film material to interlock with a basiloid container, thereby securing an upper and lower cover to the stretch-wrapped load.

For cargo consisting of goods stacked in layers, US Patent 4,845,920 describes rope-forming the edges of the stretchable film and applying them in horizontal straps so that one strap connects two layers together. This is done to take advantage of the ease of applying stretchable film, but to allow breathability of the cargo since the straps are vertically spaced apart. Similar layer-connecting straps are disclosed in EP 177 413 without rope-forming the edges of the stretchable film.

Finally, EP-A 298 799 discloses a system for stretching adhesive film to such an extent that the tear resistance of the edges requires an increase by folding some of the film edge. It also describes controlling the amount of film folded at the edges in order to create narrow film sections which allow the load to breathe.

A common disadvantage in stretch film applications is that a high degree of vertical overlap of the spiral stretch film layers is used to ensure stability. Furthermore, to securely hold the load on a pallet, many layers of stretch film are wrapped horizontally around the pallet and portions of the bottom layers of the units. Despite this effort, sufficient stability has often not been achieved, resulting in consumer and customer dissatisfaction with messy loads on a pallet due to excessive use of stretch film. Furthermore, the film that holds the load on the pallet also covers the holes in the pallet designed for forklifts to manipulate pallets. These portions of the Stretch film is often punctured by forklifts, further reducing stability and creating another aesthetic disadvantage, and this is often unacceptable for automated warehouse storage.

It is therefore an object of the present invention to provide a load which is wrapped in stretchable film and fixed to a pallet with stretchable film while having improved stability.

Another goal is to provide cargo that is wrapped in stretch film with a minimal amount of stretch film material and no or minimal amount of packaging aids.

It is another object of the invention to reduce packaging material, thereby meeting the need for decreasing packaging material consumption and improving ecological compatibility.

It is yet another object of the present invention to provide cargo secured to pallets with stretchable film, keeping the tamper recesses clear of such film while achieving an increased degree of stability.

An additional aim of the method of the invention is to reduce the time required to wrap a load in a stretchable film and to fix the load to the pallet.

Summary of the invention

The present invention relates to a load formed from a plurality of units, assembled on a pallet and wrapped with an expandable film in a spiral configuration to stabilize said load and at the same time to fix said load to the pallet. To achieve this, the expandable film combines folded or rolled edges which stabilize the load when wrapped spirally and has a rope-like lower edge when it is wrapped around the transition zone between load and pallet. The rope-like lower edge differs from the folded or rolled edges by comprising more stretchable film than the said folded or rolled edges.

In a preferred embodiment, the rope-like lower edge comprises 2 to 10 times, more preferably 5 to 10 times, the amount of stretchable film used for the folded or rolled portion of the edges.

In a preferred embodiment, the folded or rolled edges of the film are also made from less than 30 mm, more preferably 10 to 20 mm, of the width of the stretchable film.

In yet another preferred embodiment, the packaging is characterized in that the rope-like lower edge is arranged around the upper part of the pallet, sufficiently high to prevent the rope of stretchable film or the membrane of stretchable film extending against the load from being damaged by, for example, forklift trucks, which are usually used to lift pallets.

In general, the packages may contain any commonly used packaging aids such as, but not limited to, top or bottom covers, layer separating sheets, corner stabilizers or soft protectors around sharp corners, although in most cases these may be omitted.

Short description of the drawings

It is believed that the present invention will be better understood by supplementing the detailed description with drawings. The accompanying drawings have designations to identify similar or identical elements in the description.

In the drawings:

Figure 1 shows a torn, flat section of a stretchable film (1) with an upper edge (11) and a lower edge (12).

Figure 2 shows a load (2) which is formed from a plurality of units (21) on a pallet (3) assembled and wrapped in a spiral in stretch film (1) according to known techniques, but after only the first half of the wrapping has been carried out from top to bottom. The edges (11, 12) of the stretch film are flat and the fastening between the load (2) and the pallet (3) is achieved by repeatedly passing the lowermost straps (123) of flat stretch film (1) horizontally around the transition from the load to the pallet, thereby covering the pallet recesses (31).

Figure 3 shows a torn section of a stretchable film (1) with folded-over upper edge (111) and lower edge (121), as used in the invention, guided around the load,

Figure 4 shows a torn-off different section of the stretchable film (1) as used in the invention, with a folded-over upper edge (111) and a rope-like lower edge (115) in order to fix the load (2) to the pallet.

Figure 5 shows a preferred embodiment of the invention, but after only the first half of the wrapping has been carried out, from top to bottom. A load (2) is wrapped with the stretchable film (1) with folded edges, as shown in Figure 3, whereby the fastening between load (2) and pallet (3) is achieved with the stretchable film (1), as shown in Figure 4.

Figure 6 shows an alternative of the stretchable film as shown in Figure 3 with rolled upper edge (211) and rolled lower edge (212).

Figure 7 shows another alternative for the stretchable film as shown in Figures 3 or 6, with a folded top edge (111) and a Z-fold (113) in the middle of the film.

Figure 8 shows the basic method, as has been generally used in the prior art, for stretching the film (1) by passing it around a pair of rollers (41, 42) rotating at different surface speeds, the downstream roller (42) being faster than the upstream roller (41). Other rollers, which (401) are the ones supplied by an unwinding section coming film or (402) causing it to be applied against the load are also shown.

Figure 9 shows the process for producing a folded or rolled top edge (111, 211) and bottom edge (112, 212). The folding or rolling device (51, 52) forces the film edge (11, 12) to bend into folded or rolled film edges (111, 112, 211, 212). The arrangement of the device (51, 52) upstream of the stretching rollers (41, 42) is a preferred embodiment. The rope forming device (6) is shown in a non-latched position.

Figure 10 shows the process for producing a folded upper edge (111) and a rope-like lower edge (115). The rope-forming device (6) forms the stretchable film (1) into a rope-like shape to such an extent that the folding or rolling device (52) does not reach the lower edge (12).

Detailed description of the invention and preferred embodiments Product aspects of the invention

The load (2) consists of a plurality of units (21), which in turn are often packages of different sub-units. The load (2) is wrapped in a spiral shape in stretch film (1) to protect and stabilize the contents. To do this, individual straps of stretch film (1) applied around the load (2) overlap the previous strapping, often by more than 50% of the width of the film, creating a unit of the overall packaging.

Furthermore, the load (2) is also fixed to a handling and transport aid, most often to a pallet (3), in order to increase stability through the rigid support structure to facilitate handling and transport. This is done when the straps are applied horizontally to the bottom part (123) of the load (2), extending over the load (2) and over the pallet (3).

According to one part of the invention, the load (2) is wrapped in a spiral with an extensible film (1) with both edges (111, 211, 112, 212) folded or rolled, thus increasing its stability while allowing a reduction in the amount of overlap of successive strappings or combinations thereof. The other part of the invention is to firmly fix the stabilized load (2) to a pallet (3) by rope-like forming the lower edge (115) of the film (1) of the horizontal strappings to the bottom of the load (123). This rope-like formed lower edge (115) is distinguished from the folded or rolled lower edge (112) in that it is made of more extensible film material than the folded or rolled edge (112).

In a preferred version, the folded or rolled film edges (111, 211, 112, 212) are formed by folding or rolling less than 30 mm, preferably 10 mm to 20 mm. This combines the advantage of improved stability and reducing the width of the stretchable film per edge to a minimum.

In another preferred embodiment, the rope-like lower edge (115) of the stretchable film (1) does not extend over the openings (31) of the pallet (3). This ensures that the stretchable film (1) and the rope-like edge (115) are not damaged when manipulating or transporting the pallet (3), for example by using a forklift or similar device.

Edges (111, 211, 112, 212, 115) of the stretchable film can be folded or rolled or rope-like against the inside or outside of the cargo (2).

It is also possible to apply the stretchable film (1) to the load (2) with only a part of its total length folded over, rolled over or roped over. For example, the first part of the film may have flat edges (11, 12) to cover the package once with the flat film, and the latter part may, in accordance with the invention, have folded over, rolled over and roped over edges (11, 12) have formed edges (111, 211, 112, 212, 115) or vice versa.

Another possibility to achieve the stabilizing effect for the load (2) is to fold one or more central parts of the film in a Z-configuration, producing a Z-fold (113). This would require a more complicated process, but has the advantage of avoiding that upper and/or lower folded or rolled edges (111, 211, 112, 212) of successive spirally guided strappings overlap and thereby exert particularly high partial pressure on the load (2). It is particularly advantageous to have an upper folded or rolled edge (111, 211) and a central Z-fold (113).

Advantages of stability or reduced material consumption or combinations thereof are independent of the particular load (2) or the particular way of assembling it. Hard, soft or even crushable units (21) forming the load (2) which are stacked in sequence or randomly stacked on a pallet can benefit from the invention.

Likewise, cargo (2) requiring breathability can be packed using the invention. For example, spiral wrapping steep enough to avoid overlapping or wrapping and rolling the width of the stretch film sufficiently to prevent overlapping of successive wraps of stretch film (1) can be used to allow breathability.

Likewise, the selection of a particular film material is not essential to the invention. The invention can be made essentially with any existing stretchable film materials that are normally used. Film materials with a one-sided self-adhesion are preferred because they help to stabilize the folded or rolled and the rope-like edges.

Process and device aspects of the invention

To produce load (2) as described above, the following process steps are required: unrolling the stretchable film (1), stretching it and attaching it to the load. As indicated in the prior art, many methods and devices perform the above. Typically, the process involves an unrolling station from which the film is pulled around a non-driven guide roller (401) to a first driven stretch roller (41) which rotates at a lower peripheral speed than the second driven stretch roller (42). The difference in speed produces the stretching of the film (1), which is guided, for example, by another non-driven guide roller (402) and attached to the palletized load (2) by relative rotation of the palletized load and the stretchable film (1). According to the invention, this standard process is supplemented by wrapping or rolling and by rope-forming the film edges (111, 211, 112, 212, 115) to achieve the stretched extensible film (1) of the invention. Placing standard equipment, such as a roller or a folding board or bar (51, 52, 6), as an obstacle in the path of the film edge (11, 12) gradually bends the film edge (11, 12), thus achieving the desired result (111, 211, 112, 212, 115). The depth and angle at which these standard equipment items (51, 52, 6) are arranged in the path of the film edge (11, 12) are decisive as to whether a roll or a rope-like formation occurs. Accordingly, the desired film edge configuration can easily be defined by taking into account the properties of the load (2), the film (1) and the manipulation requirements.

In order to achieve a folding or rolling of the film edges (111, 211, 112, 212) when wrapping the load and a rope-shaped lower film edge (115) when fastening the load (2) to the pallet 3, a control device takes hold of the rope-forming equipment only during the period when the strapping is made on the lower part (123). The control device is not shown in the figures, but can be, for example, a mechanical, electrical or magnetic sensor connected to a suitable activator to move the rope forming equipment. A preferred embodiment is to use a purely mechanical sensor/activator combination.

As will become clearer from the example, the application of this method and this system will lead to the additional advantage of reduced time required to wrap a load (2) in the stretchable film (1) due to the reduced number of strappings around the load (2) and the reduced overlap between successive strappings.

It is not essential to the method where along the path of the film the folding or rolling or rope-forming operation takes place. However, it has been found that it is most advantageous to have the folding or rolling devices (51, 52) installed upstream of the stretching rollers (41, 42) and the rope-forming device (6) installed downstream of the stretching rollers (41, 42).

The process can be further improved by squeezing rollers, which press the formed, folded or rolled or rope-like edges (111, 211, 112, 212, 115) closely together. Squeezing rollers are not shown in the figures. They can be particularly advantageous where stretchable film (1) with little or no adhesive ability is used.

In a preferred method and device embodiment according to the invention, the combination of the lower edge folding or rolling step with the rope forming step is achieved by using a device or device support that is movable with respect to the stretchable film (1).

For cargo (2) that requires breathability, it may also be advantageous, for example, to install adjustable or movable handling or folding devices (51, 52).

Example

Specific examples are described below, which show in detail the application of the invention.

A standard CEKA Dominant satellite stretch wrapper is used as a base. Loads consisting of soft polybag goods are assembled on a pallet. The conventional cardboard corner pieces which were usually necessary to complete the load so that it had acceptable stability are omitted. Two rods are installed on the satellite perpendicular to the plane of the stretch film at a slight angle in the direction of travel of the film. The rods are installed on arms upstream of the stretch rollers. The rods create obstructions, extending 15 mm into the path of the stretch film, measured from the edges of the stretch film. The rods bend the self-adhesive side of the film edges against the self-adhesive side of the film and the fold thus formed is compressed as the film is stretched around the stretch rollers. Squeeze rollers are not required as the self-adhesive ability is sufficient to overcome the internal material elasticity.

Behind the stretching rollers, an hourglass-shaped rope-forming roller is installed on an arm which is movable by a lifting magnet. The magnet is controlled by an electromagnetic switch which is switched on when the horizontal straps are made by securing the load to the pallet. Alternatively, the hourglass-shaped roller can be installed on an arm which fixes it at the desired height by mechanically limiting it from moving further downwards when the horizontal straps are made. The hourglass-shaped rope-forming roller extends 150 mm into the film width when engaged. The axis of the rope-forming roller is approximately perpendicular to the plane of the film.

In this engaged position, the rope-forming roller is at the same level as the upper part of the pallet, but not at or below the level of the manipulation openings in the pallet.

The following table shows variables and in particular the improvements which can be achieved by embodiments according to the invention in comparison with equivalent designs obtained by known techniques. For both examples, the stretch film material is polyethylene and the application device is a stretch wrap machine of the CEKA Dominant-Satellite type.

Stability in these examples was assessed by placing the products on an inclined plane of 24º and measuring the curvature of a 2 m high load against a line perpendicular to the pallet. Positive rating was given for less than 5 cm of curvature and negative rating was given for more than 10 cm of curvature. Loads that overturned were excluded but retained. inventive embodiment in general inventive embodiment but without wrapping, rolling or rope-forming steps cargo cardboard boxes thickness of the stretchable film extension of the film width of the film width of the film used per folded edge width of the film used per rope-formed edge number of film strappings index of the film used for total wrapping total time to wrap a pallet no folded edges no rope-like foil edge inventive design generally inventive design but without wrapping, rolling or rope forming steps Cargo cardboard boxes index of efficiency openings in the pallet degree of stability after 2 hours not covered positive (also after 2 days) covered and punctured negative Cargo soft poly bags thickness of the stretch film extension of the film film width film width used per folded edge film width used per roped edge number of film straps index of the film used for total wrapping openings in the pallet packaging aids not required no folded edges no roped edges carton corners negative, sometimes tipping over

Although many preferred and optional embodiments have been described in detail and illustrated by the drawings and examples, many variations are possible which still fall within the scope of the claimed invention.

Claims (12)

1. A load (2) which is formed from a plurality of units (21), assembled on a pallet (3) and wrapped in a spiral shape with an expandable film (1), characterized in that both edges (111, 211, 112, 212) of said film (1) are folded over or rolled where said film (1) goes around said load (2), and in that the lower edge (11) of said film (1) which forms the strapping on the lower part (123) of the load (2) is rope-like, said rope-like lower edge (115) being formed from more film (1) than said folded or rolled lower edge (112, 212). 2. A palletized load (2) according to claim 1, characterized in that the folded or rolled edges (111, 211, 112, 212) of said film (1) are formed by folding or rolling less than 30 mm, preferably 10 to 20 mm, of the width of said film (1). 3. A palletized load (2) according to one of the preceding claims, characterized in that said rope-like lower edge (115) of said film comprises a quantity of film of two to ten times the quantity of said folded or rolled lower edge of film (112, 212). 4. A palletized load (2) according to one of the preceding claims, characterized in that said rope-like formed lower film edge (115) leaves the openings (31) in said pallet (3) uncovered. 5. A palletized load (2) which is formed by a plurality of units (21), assembled on a pallet (3) and wrapped in a spiral shape with an expandable film (1), characterized in that an edge (111, 211, 112, 212) of said film (1) is folded over or rolled where said film (1) surrounds said load (2); at least one Z-fold (113) is provided in the middle section of the film (1); and the lower edge (115) of said film (1) forming the strapping on the lower part (123) of the load (2) is rope-like, said rope-like lower edge (115) being formed by more film (1) than said folded or rolled edge (111, 211, 112, 212). 6. A method suitable for producing palletized load (2) according to any one of the preceding claims, which comprises -Unrolling and stretching the said film (1) and -Applying said film (1) to a palletized load (2) in a spiral configuration by rotating said palletized load (2) in relation to said unrolling and stretching film and simultaneously - vertical up and down movement of said film characterized in that along the path of said film (1), preferably before said stretching process, the edges of said film (111, 211, 112, 212) are folded over or rolled and the lower edge (115) of said film is formed into a rope-like shape when strapping around the lower part (123) of said load (2) and around the upper part of the pallet (3). 7. A method according to claim 6, characterized in that the said folded or rolled film edges (111, 211, 112, 212) or the rope-like film edge (115) are stabilized in an additional step by pressing the folds or rolls or the rope together. 8. Device for carrying out the method according to claim 7, which comprises a load frame, a film unwinding device, a film stretching device, a drive for rotating said load frame, or a drive for rotating said unwinding and stretching device around said load (2), characterized in that it further comprises Guide means (51, 52) for folding or rolling the edges (111, 211, 112, 212) of said film (1), and Guide means (6) for forming the lower edge (115) of said film (1) in a rope-like manner, which are actuated by a control device so that said rope-like edge (115) is only guided around said pallet (3). 9. A machine according to claim 8, characterized in that said guide means (51, 52) for folding or rolling or said guide means (6) for rope forming are folding bars, folding rollers or folding plates. 10. A machine according to claim 8 or 9, characterized in that said control device is a mechanical stop device. 11. A machine according to claim 8, 9 or 10, characterized in that said guide means forming the folded or rolled edges (111, 211, 112, 212) are mounted on support arms which allow said guide means (51, 52, 6) to be gripped or released. 12. A machine according to claim 8, 9, 10 or 11, characterized in that squeezing rollers are mounted after said guide means forming the folded or rolled edges (111, 112).