Stretch hood wrapping system

Abstract

The invention discloses a stretch hood wrapping system that includes a stretcher, a carrying frame, and a manipulator configured to be operable to stretch wrap an object from a designated surface thereof with a hood comprising an elastic film sleeve, with the stretcher stretching the sleeve, the carrying frame receiving the stretched sleeve from the stretcher, the manipulator locating the carrying frame against a designated surface of the object and passing the carrying frame over the object from its designated surface to proximate an opposing end thereof to stretch the sleeve over the object from its designated surface and along sides thereof, thereby allowing the sleeve to be transferred from the carrying frame onto the object, to wrap the object with a stretch hood. The invention extends to a carrying frame for such a system and a method of wrapping an object with a stretch hood.

Description

[0001] STRETCH HOOD WRAPPING SYSTEM

[0002] FIELD OF THE INVENTION

[0003] This invention relates to a stretch hood wrapping system and an associated method for, and apparatus used to, wrap palletised goods.

[0004] BACKGROUND TO THE INVENTION

[0005] The wrapping and sealing of palletised goods are required to ensure load stability of goods transported on a pallet, and to protect such goods from adverse weather such as rain. By way of example, cement powder is bagged in paper bags and stacked on a pallet. Such a pallet is lifted by a forklift onto a truck or train for transportation, sometimes uncovered. Cement reacts with water to solidify, so any rain that may fall onto such a pallet is likely to ruin at least some of the cement bags on such a pallet.

[0006] Different techniques have been developed to cover such palletised goods. These include stretch wrapping, shrink wrapping, and the use of a stretch hood.

[0007] In stretch wrapping a roll of stretchable film is wrapped around the goods on a pallet. The bags on the pallet are only covered in the horizontal direction, which leaves the top and bottom of the pallet exposed. The bottom is not much of a problem, but the uncovered top is a problem in respect of adverse weather. For that reason, a separate sheet of film must be used to cover the top of such a pallet, when required. The stretch wrap is strong, but overuse of such film is common, and the end of the film can become loose from where it is typically tucked in, and that creates a risk for entanglement during handling of such pallets. The need to separately add a top film adds to the cost and time requirement for using stretch wrapping.

[0008] In shrink wrapping a hood of shrink film, which consists of a tube with one open end and one closed end, is pulled from the top of the pallet over the goods and the pallet. The closed end of the hood is thus located over the top of the goods on the pallet which solves the need for a separate sheet of film for the top. The hood is then heated which causes it to shrink onto the palletised goods. A problem with such a system is that the film becomes opaque during heating, which makes it difficult to scan barcodes that are printed on palletised goods. This may tempt a worker to tear the film to gain access to a barcode, which compromises the packaging and partly defeats its purpose by compromising its ability to seal the palletised goods. To avoid this, a separate barcode must be fixed to the film after shrink wrapping, which adds costs to the process and time to affix it. There is also the risk of incorrect barcoding, since the point of sealing goods on pallet is typically removed from the point where barcodes are affixed to bags. In some instances, bags are printed with barcodes which means an extra supply of barcodes printed on stickers is required at the point where the pallet wrapping occurs. The use of heat for the shrinking action also creates the possibility that product bags may fuze together, and inherent to the use of heat is the risk of fire. A further problem is that heating requires energy, and energy losses during such heating processes is significant. Increasing electricity costs and instability in the supply of electricity from energy grids detract from the attractiveness of this option.

[0009] The use of a stretch hood is basically the same as shrink hood, apart from not using heat to shrink the hood over the palletised goods. Instead, the hood is manufactured from a film of stretchable material, and it is stretched within its elastic limit. It is pulled in this stretched condition from the top over a pallet of goods, and simply released to close onto the palleted goods due to elastic recovery of the film. This provides a very even fit of the plastic hood over palletised products. Barcodes are easily readable through the film. The dimensions of the film can be determined and controlled very accurately to compliment the dimensions of the packaged goods which dramatically reduces waste.

[0010] Although the quality and performance of packaging produced using the stretch hood system is very good, and much more economical and of better quality than stretch wrapping or shrink wrapping, conventional stretch hood systems using this technique are not without limitations.

[0011] In a conventional stretch hood system, a pallet with for example stacked bags is delivered onto a conveyor that leads into a sealing space within the conventional stretch hood system. The pallet must be placed very accurately, typically within several millimetres, by the conveyor in the sealing space.

[0012] A frame is used to stretch a plastic material hood open to have an internal size that is greater than the plan dimensions of the palletised goods. The frame is passed over the pallet from its top, in the process drawing the stretched open end of the hood over the top of the pallet. This means the internal dimensions of the frame is greater than the outer dimensions of the palletised goods. If the pallet is square in plan, then a square frame is used. The plastic hood is located on the outer surface of the frame, and located against the frame while it is pulled over the pallet of bags. This locates the stretched plastic hood over the palletised bags, from its top to its bottom.

[0013] The open end of the hood is pulled down over the top of the bags in the upper layer of bags on the pallet and stretched down from the closed top of the hood. When the frame reaches the pallet itself, the plastic hood which has been cut to size reaches its end, pulls off the frame and snaps under resilient force onto the bottom layer of bags. It may also overlap with the side of the pallet.

[0014] The frame has a very accurate and very specific vertical path within which it must travel. The pallet of bags must be placed directly underneath it, accurately centred relative to the centre of the frame, and it must be squared to the frame. Only a small deviation in position could be accommodated by the extent to which the inner dimensions of the frame exceed the pallet outer dimensions. However, a pallet of bags that is not orientated squarely with the frame causes the corners of the frame to not descend over the corners of the pallet, and instead the sides of the frame will catch onto the corners of the stack of palletised bags. This could interfere with the operation of the stretch hood system and tear the stretch hood or tear bags on the pallet.

[0015] This can be prevented to some extent by increasing the dimensions of the frame, but this will then either require a larger, and hence more expensive, stretch hood system or it places a limit on the size of palletised bags that can be handled by such a system. This indirectly also increases the effective cost of the stretch hood system. None of these options are preferable and the practical solution to this inherent limitation of conventional stretch hood systems is to position the palletised bags very accurately within the sealing space, with the requirement that the pallet must be centred and squared very accurately relative to the frame that holds the stretched hood.

[0016] The equipment used to achieve this is very expensive and requires extremely tight setup tolerances and accuracy of operation, and frequent high-level maintenance. The frame is unforgiving in terms of its requirements, and the pallet must be positioned accurately in relation it, not the other way around. Such systems are typically unforgiving of, and practically have zero tolerance for, deviations.

[0017] Additionally, the conventional stretch hood system is a fixed installation, with a conveyor belt leading into it and conveyor belt leading out of it. A compromise to even a small component forming part of the system, whether upstream or downstream, has the potential to disrupt the entire system. For example, a broken bearing on single roller forming part of a conveyor roller leading into the system can misalign the pallets and cause the system to malfunction. That forces the system to be stopped until that component can be fixed. If that component is not readily available, the system is offline until it arrives. In an era of global supply interruptions even a mundane item such as a roller bearing can disrupt such an entire system. The technical support required for such systems are often located in major cities in so-called “first world” countries and any installation in a remote area or in a so-called “third world” country will be vulnerable for delays where technical support must be flown in. This can lead to delays of several days or weeks for apparently minor issues.

[0018] With a single conveyor belt leading into it and a single conveyor belt leading out of it, the conventional system is also constrained in terms of production tempo to the rate achievable by the slowest component in the system, which is the system’s rate limiting step. For example, delivery of palletised goods faster than what sealed pallets can be cleared from the single conveyor belt leading out of the system will simply cause a pile up of unsealed pallets at the infeed side of the system.

[0019] Conventional stretch hood packaging systems are also very costly to acquire and to maintain, with long lead times for their manufacturing, and long installation and commissioning times. It is not uncommon for such a system to require a full month for installation and commissioning.

[0020] Only select high-end customers can typically afford conventional stretch hood packaging systems, and other customers have no option but to resort to older techniques, such as stretch wrapping or shrink wrapping, which provide less than optimal results.

[0021] OBJECTIVE OF THE INVENTION

[0022] It is an objective of the invention to provide a stretch hood wrapping system, an associated method, and associated apparatus which at least partly overcomes the abovementioned problems.

[0023] SUMMARY OF THE INVENTION

[0024] In accordance with this invention there is provided a stretch hood wrapping system for an object, with the system including a stretcher, a carrying frame, and a manipulator that are configured to be operable to stretch wrap the object from a designated surface thereof with a hood comprising an elastic film sleeve, with the stretcher configured to stretch the sleeve, the carrying frame configured to receive the stretched sleeve from the stretcher, the manipulator configured and operable to locate the carrying frame against a designated surface of the object and to pass the carrying frame over the object from its designated surface to proximate an opposing end thereof to stretch the sleeve over the object from its designated surface and along sides thereof, thereby allowing the sleeve to be transferred from the carrying frame onto the object to wrap the object from its designated surface and along its sides with a stretch hood.

[0025] There is further provided for the elastic film sleeve to have a sidewall that extends between an open end a closed end of the sleeve, and with the sidewall defining inside the sleeve a sleeve inner space on a cross-sectional plane that is normal to a longitudinal axis of the sleeve; with the stretcher including a plurality of grippers each being shaped and configured to releasable grip and stretch at least part of the sidewall for dimensions of the sleeve inner space to exceed dimensions of the designated surface of the object, with the sidewall being receivable substantially bunched-up on the grippers and the closed end of the sleeve extending between the grippers; with the carrying frame being shaped and configured to be securable to the manipulator, and having a continuous circumferential wall which defines a frame inner space on the operative inside of the wall that is complementary shaped to a shape of the designated surface of the object, and sized for dimensions of the frame inner space to exceed dimensions of the designated surface of the object; with the manipulator being configured and operable to locate the carrying frame against a designated surface of the object by - locating the carrying frame in a position between the grippers and inside the stretched and still bunched-up sidewall of the sleeve, moving the carrying frame against the operatively inner surface of the closed- end of the stretched sleeve to transfer the stretched and still bunched-up sidewall of the sleeve onto the outer surface of the carrying frame, thereby transferring the sleeve onto the carrying frame, with the still bunched-up sidewall of the sleeve located against an operatively outer surface of the carrying frame, and rotating the carrying frame to orientate the operatively outer surface of the closed end of the stretched sleeve to be coplanar with and facing the designated surface of the object. There is further provided for each gripper to comprise an arm terminating in a hook with the hooks with the hooks of the plurality of grippers defining between them a stretching plane, with each arm being movable coplanar to the stretching plane between an inner position and an outer position, with the inner position of each arm being closer to a centre of the stretching plane than its outer position, operatively enabling the bunched-up sidewall of the sleeve to be located over the hooks with the arms located in their inner positions and to be stretched between the hooks with movement of the arms from their inner positions to their outer positions, to stretch the film between the hooks in the stretching plane.

[0026] There is further provided for each hook to terminate in an end that is provided with at least one roller.

[0027] There is also provided for each arm to be provided with a clamp terminating in an end that is provided with a roller guide, with each clamp being movable between a disengaged position in which the end of the clamp is distal from the hook and an engaged position in which the roller guide is located in abutment with the free of its respective hook against the roller on the end of the hook, in use against the bunched-up sidewall of the sleeve located on the hook.

[0028] There is further provided for the clamp to be secured to a cylinder that is operable between a compressed position in which the clamp is in the disengaged position and an extended position in which the clamp is in the engaged position.

[0029] There is further provided for the carrying frame to include a base with a bracket shaped and configured to be securable to the manipulator.

[0030] There is further provided for the circumferential wall of the carrying frame to include an operative top edge and an operative bottom edge, with a flange extending at least from proximate the bottom edge of the wall for at least part of the circumference of the wall and with the flange being directed outward from the wall.

[0031] There is further provided for the top edge of the carrying frame to be provided with a set of circumferential driven rollers, which are connected internally in the frame by means of drive shafts and gears at corners of the frame to at least one electrical motor.

[0032] There is still further provided for the stretch hood wrapping system to include a control system configured to determine the speed with which the manipulator passes the carrying frame over the object, for a processor associated with the control system to determine a complimentary speed of rotation for the rollers to ensure the stretched sleeve is transferred from the carrying frame at substantially the same rate that the manipulator passes the carrying frame over the object, and with control system being configured to control the electrical motors to drive the rollers at the complimentary speed of rotation.

[0033] There is further provided for the designated surface of the object to be a free end of the object comprising its upper surface, and for the object to comprise a palletised product.

[0034] There is further provided for each arm of the gripper to be slidingly movable between its inner position and its outer position.

[0035] There is still further provided for the stretcher preferably to include a set of legs supporting a stretcher frame, with the arms being movable secured to the stretcher frame.

[0036] There is also provided for the manipulator to comprise a programmable robot.

[0037] In accordance with a further aspect of the invention there is provided a carrying frame for a stretch hood wrapping system, with the frame being shaped and configured to be securable to a manipulator that is configured operatively to stretch wrap an object from a designated surface thereof with a hood comprising an elastic film sleeve by passing the carrying frame carrying the sleeve bunched-up on the frame over the object, with the frame including a continuous circumferential wall which defines a frame inner space on the operative inside of the wall that is complementary shaped to a shape of the designated surface of the object, and which is sized for dimensions of the frame inner space to exceed dimensions of the designated surface of the object.

[0038] There is further provided for the circumferential wall of the carrying frame to include an operative top edge and an operative bottom edge, with a flange extending at least from proximate the bottom edge of the wall for at least part of the circumference of the wall and with the flange being directed outward from the wall.

[0039] There is also provided for the top edge of the carrying frame to be provided with a set of circumferential driven rollers, which are connected internally in the frame by means of drive shafts and gears at corners of the frame to at least one electrical motor. In accordance with a still further aspect of the invention there is provided a method of wrapping an object with a stretch hood by locating a stretched sleeve over a carrying frame that is shaped and sized to have inner dimensions exceeding the outer dimensions of a designated surface of the object, orientating the operatively upper surface of the stretched sleeve to be coplanar with and face the designated surface of the object, passing the carrying frame over the object from its designated surface to proximate an opposing end thereof to stretch the sleeve over the object from its designated surface and along sides thereof, thereby allowing the sleeve to be transferred from the carrying frame onto the object, to wrap the product from its designated surface and along its sides with a stretch hood.

[0040] There is also provided for the method to include determining the speed with which the manipulator passes the carrying frame over the object, determining a complimentary speed of rotation for a set of circumferential driven rollers on the top edge of the carrying frame, which are connected internally in the frame by means of drive shafts and gears at corners of the frame to at least one electrical motor, to ensure the stretched sleeve is transferred from the carrying frame at substantially the same rate that the manipulator passes the carrying frame over the object, and controlling the electrical motors to drive the rollers at the complimentary speed of rotation.

[0041] These and other features of the invention are described in more detail below.

[0042] BRIEF DESCRIPTION OF THE DRAWINGS

[0043] A preferred embodiment of the invention are described by way of example only and with reference to the accompanying drawings in which:

[0044] Figure 1 is a side elevation view of a stretch hood wrapping system according to an embodiment of the invention, showing a stretcher, a carrying frame and a manipulator in the form of a programmable robotic manipulator, integrated with an associated sleeve forming assembly;

[0045] Figure 2 is a plan view of the stretcher of Figure 1 in the sleeve forming assembly;

[0046] Figure 3 is a plan view of the stretcher of Figure 1 , showing detail of one of its corners;

[0047] Figure 4 is a side elevation view of one arm at a corner of the stretcher of the system shown in Figure 1 , with the guide roller in the disengaged position;

[0048] Figure 5 is a side elevation view of the stretcher of Figure 4 with the guide roller in the engaged position; Figure 6 is a plan view of the carrying frame of the system shown in Figure 1 , with detail of the internal drive transmission mechanism at one corner thereof;

[0049] Figure 7 is a side elevation view of the carrying frame of Figure 6;

[0050] Figure 8 is a plan view of the stretcher of the system shown in Figure 1 and the carrying frame secured to the manipulator, showing movement of the carrying frame between the stretcher and a position where the stretched hood can be pulled over a pallet of goods;

[0051] Figure 9 is a side elevation view of the system shown in Figure 8 with the manipulator moving the carrying frame in position underneath the stretcher;

[0052] Figure 10 is a plan view of the system as shown in Figure 9;

[0053] Figure 11 is a side elevation view of the system shown in Figure 10 with the manipulator raising the carrying frame up into abutment with the operative lower surface of the stretched plastic hood;

[0054] Figure 12 is a plan view of the system shown in Figure 11 with each guide roller moving to its disengaged position;

[0055] Figure 13 is a plan view of the system shown in Figure 12 with the manipulator moving the carrying frame including the stretched hood from the stretcher to the pallet of bags;

[0056] Figure 14 is a side elevation view of the system shown in Figure 13 with the manipulator rotating the carrying frame including the stretched hood on it around a horizontal axis above the pallet of goods;

[0057] Figure 15 is a side elevation view of the system shown in Figure 14 with the manipulator lowering the carrying frame over the pallet of goods with the plastic hood first coming in contact with the upper surface of the upper layer of goods on the pallet;

[0058] Figure 16 shows the view of the system of Figure 15 with the carrying frame proximate the pallet;

[0059] Figure 17 shows the view of the system of Figure 16 with the manipulator having pulled the carrying frame down to the bottom of the pallet and the with plastic hood stretched over the outer surface of the goods on the pallet, and the manipulator withdrawing the carrying frame to the top of the pallet of goods leaving the hood located over the pallets of goods;

[0060] Figure 18 is a plan view of the system shown in Figure 17 with the manipulator moving the empty carrying frame back toward the stretcher;

[0061] Figure 19 is a side plan view of the manipulator and carrying frame shown in Figure 18 with the manipulator positioning the empty carrying frame horizontally in the stretcher for the carrying frame to collect a new stretched hood from the stretcher;

[0062] Figure 20 is a is a plan view of the system shown in Figure 19, showing also the pallet goods that have been covered with the stretched hood being replaced by an uncovered pallet of goods for it to be covered next by the system; and

[0063] Figure 21 is a side elevation view of the manipulator and carrying frame shown in Figure 20 with the manipulator raising the carrying frame underneath a stretched hood to collect it from the stretcher.

[0064] DETAILED DESCRIPTION OF THE INVENTION

[0065] Before embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings.

[0066] The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0067] The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

[0068] Unless specified or limited otherwise, the terms "mounted", "connected", "engaged" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings and are thus intended to include direct connections between two members without any other members interposed therebetween and indirect connections between members in which one or more other members are interposed therebetween. Further, "connected" and "engaged" are not restricted to physical or mechanical connections or couplings. Additionally, the words "lower", "upper", "upward", "down" and "downward" designate directions in the drawings to which reference is made.

[0069] The terminology includes the words specifically mentioned above, derivatives thereof, and words or similar import. It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the," and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

[0070] A preferred embodiment of a stretch hood wrapping system (1) according to the invention is configured for use with the sealing of palletised bags of particulate material, such as cement bags (2). These bags (2) are stacked in layers onto a pallet (3), with the orientation of each successive row being offset to the row beneath it. This creates an interlocking effect between the bags (2). Once packed, the bags (2) on the pallet (3) are sealed to protect their content against negative environmental impact, such as adverse weather conditions. The bags (2) are sealed using a stretch hood wrapping system according to the invention.

[0071] The stretch hood wrapping system (1) of the invention includes a stretcher (4), a carrying frame (5), and a manipulator (6). The stretch hood wrapping system (1) is associated with a sleeve forming assembly (7) which receives an infeed from rolls of plastic sheet, of which one (8) is shown in Figures 1 and 2. The plastic sheet (9A) is layered and secured lengthwise along its edges to form a sleeve (9). This sleeve (9) is closed at one end to form open-ended sleeve (9). The sleeve forming assembly (7) is comprised of existing technology.

[0072] The stretch hood wrapping system (1) of the invention receives such an open-ended sleeve

[0073] (9) from the sleeve forming assembly (7), stretches it to form an open-ended stretched hood

[0074] (10), and locates it over the bags (2) on the pallet (3).

[0075] The stretcher (4) of the stretch hood wrapping system (1) includes a set of four arms (12) that extend from a frame (11). Each of four arms (12) terminates in a hook (13) at an end located within the frame (11). As shown in Figure 3, the arms (12) are slidingly movable (12A) relative to the frame (11) to enable each hook (13) to be moved between an outer position (14) and an inner position (15).

[0076] As shown in Figures 4 and 5, the hook (13) of each arm (12) is provided with a set of rollers (16) facing outward relative to the centre of the frame (11). Each hook (13) is also provided with a roller guide (17). Each roller guide (17) is secured to an extendable arm (18) that is movable between a disengaged position (19), shown in Figure 4, and an engaged position (20) shown in Figure 5. As shown in Figure 6, the carrying frame (5) has a square shape and is sized for its inner dimensions to exceed the outer dimensions of the set of palletised bags (2), which allows the carrying frame (5) to freely pass over the palletised bags (2).

[0077] The carrying frame (5) is provided with a bracket (21) that allows it to be secured to the manipulator (6), as described in more detail below. The carrying frame (6) has a set of four sidewalls (22) with 45° corners (23), as shown in Figure 6.

[0078] As shown in Figure 7, in its upright configuration, the top edge (24) of the carrying frame (5) is provided with a set of driven rollers (25). The driven rollers (25) are connected internally in the body of the frame (5) by means of draft shafts (26) and gears (27) at the 45° corners (23) of the top edge (24) to a set of electrical motors (28). The material of which the driven rollers (25) is manufactured, is selected to provide sufficient grip to hold the stretched sleeve (9) yet is still smooth enough to avoid tearing it and to allow it to smoothly roll off from the driven rollers (25).

[0079] Still in its upright configuration, the bottom edge (29) of the carrying frame (5) is provided with a set of outwardly projecting circumferential flanges (30), which extend from the sidewalls (22) but not from the 45° corners (23) of the carrying frame (5). This is shown in Figures 6 and 7.

[0080] The body of the carrying frame (5), between the top edge (24) with the driven rollers (25) and the bottom edge (29) with the circumferential flanges (30), has a depth that is sufficient to receive the bulk of a section of the sleeve (9) that is to be formed into a stretched hood (10), bunched-up over the sidewalls (22) onto the flanges (30).

[0081] The driven rollers (25) are used to control the transfer of a stretched sleeve (9) from the carrying frame (5) onto the palletised bags (2). This is described in more detail below.

[0082] In this embodiment, the manipulator (6) comprises a programmable robot (31), with an arm (32) that can be fitted to the bracket (21) of the carrying frame (5). This allows the carrying frame (5) to be releasably secured to the robot (31), for it to manipulate the carrying frame (5), including to raise it up and down and to rotate it through the horizontal axis. This allows the robot (31) to move the carrying frame (5) relative to the stretcher (4) and between the stretcher (4) and the position where the palletised bags (2) are located, and up and down relative to the palletised bags (2). As shown in Figure 1 , the entire assembly (1), which includes the stretcher (4) and the sleeve forming assembly (7), is secured to a movable frame (11). This allows the entire assembly (1 and 7), if required without a robot (31), to be packed into a container and to be moved to a site and by means of the movable frame (11) to be located in a desired position relative to a robot (31).

[0083] In use, a tube of plastic is film is created by aligning two sheets of film, heat sealing them along their longitudinal edges and across it at a predetermined length to create the sleeve (9) with one open end and one closed end. This is done in conventional manner in the sleeve forming assembly (7) that precedes the stretcher (4).

[0084] The sleeve (9) is fed to a position above the stretcher (4), where it is opened to its normal unstretched size and leading with its open end located over the hooks (13) of the stretcher (4). The closed end of the sleeve (9) is located above the hooks (13), with the sidewalls of the sleeve (9) being collected bunched-up on the outsides of the hooks (13), over the rollers (16) of the hooks (13).

[0085] When the sleeve (9) is fully collected, bunched-up, on the hooks (13), each roller guide (17) is moved into its engaged position, which press the sidewalls of the sleeve (9) against the rollers (16) of the hooks (13). In this condition, the sleeve (9) is still unstretched but is located over the hooks (13) and held in position by the roller guides (17) on the hooks (13). Each arm (18) of the stretcher (4) is still in its inner position (15).

[0086] The arms (18) of the stretcher (4) are then moved to their respective outer positions (14), which stretches the sleeve (9) between the hooks (13) to a predetermined degree. The arms (18) are retracted far enough for the area between the hooks (13), and thus within the space created underneath the stretched sleeve (9), to be greater than the upper surface (33) area of the palletised bags (2).

[0087] The robot (31) positions the carrying frame (5), held by the bracket (21), underneath the stretcher (4) and substantially centred between the four hooks (13), as shown in Figures 9 and 10. The robot (31) is then used to raise the carrying frame (3) upwards from below the hooks (13) and in between them, as shown in Figures 11 and 12. The top edge (24) of the carrying frame (5) is thus pushed up against the then lower surface of the stretched sleeve (9). The carrying frame (2) is pushed further up which transfers the stretched sleeve (9) onto the carrying frame (5) by pushing the stretched sleeve (9) off the hooks (13), as shown in Figures 11 and 12.

[0088] The carrying frame (5) is now raised clear above the stretcher (4). The robot (31) moves the carrying frame (5) with the bunched-up stretched sleeve (9) on it out of the now empty stretcher

[0089] (4) and over the palletised bags (2), as shown in Figure 13.

[0090] The carrying frame (5) is then rotated (5A) around its horizontal axis through 180°, as shown in Figure 14. This effectively turns the carrying frame (5) upside down, which orientates the top edge (24) of the carrying frame (5) over which the stretched sleeve (9) is contained to face downward to the upper surface (33) of the palletised bags (2).

[0091] As shown in Figure 15, the robot (31) then lowers (5B) the carrying frame (5) with stretched sleeve (9) on it over the palletised bags (2), which pushes the closed end of the stretched sleeve (9) against the upper surface (33) of the palletised bags (2).

[0092] The inner dimensions of the carrying frame (5) exceed the outer dimensions of the palletised bags (2), which allows it to freely pass over it. With continued downward movement by the robot (31), the stretched sleeve (10) is drawn against the upper surface (33) of the palletised bags (2), which peels the bunched-up stretched sleeve (9) under tension from the upturned top edge (24) of the carrying frame (5) away from the upturned bottom edge (29) and the circumferential flanges (30) of the carrying frame (5).

[0093] Since the stretched sleeve (9) is drawn across the upturned top edge (24) of the carrying frame

[0094] (5) as it moves down over the palletised goods (2), the stretched sleeve (9) cannot easily dislodge from the carrying frame (5).

[0095] The electrical motors (28) drive the rollers (25) on the upturned top edge (24) at a speed that is complimentary, and is synchronised with, the speed with which the robot (31) lowers the carrying frame (5) from the top (34) to the bottom (35) of the palletised bags (2).

[0096] The speed of the electrical motors (28) is controlled by a control system to be complimentary to the lowering speed of the carrying frame (5) to ensure that the rollers (25) don’t rotate substantially slower than the lowering speed of the carrying frame (5), since that will place excess tension in the sleeve (9) when it is pulled from the frame (5) which may tear the sleeve (9). This also ensures that the rollers (25) don’t rotate substantially faster than the lowering speed of the carrying frame (5), since that could bundle the stretched sleeve (9) onto the palletised bags (2) before it is properly located on them.

[0097] The control system determines the vertical speed with which the robot (31) lowers the carrying frame (5) from the top (34) to the bottom (35) of the palletised bags (2). This is converted by a processor associated with the control system to a complimentary speed of rotation for the rollers (25) to ensure that the rollers (25) don’t rotate substantially slower than the lowering speed of the carrying frame (5). The control system then controls the electrical motors (28) to drive the rollers (25) at the required speed to match the vertical speed with which the carrying frame (5) is lowered over the palletised bags (2).

[0098] In this manner, the stretched sleeve (9) is transferred onto the palletised bags (2) to form a smoothly stretched hood (10) on the palletised bags (2).

[0099] The length of the sleeve (9) is selected such that when the carrying frame (5) reaches (5C), as shown in Figure 16, the pallet (3) itself, the sleeve (9) reaches the end of its length, and it elastically closes onto the base of the palletised bags (2) and the edge of the pallet (3) itself. This seals the palletised bags (2) from the top (34) to the bottom (35) with a single closed-end stretched hood (10).

[0100] When this is done, the robot (31) raises (5D) the now empty carrying frame (5) back to the top (34) of the palletised bags (2), and lifts it clear from it, as shown in Figure 17. The robot (31) rotates the carrying frame (5) again through 180° and returns (5E) it to the empty stretcher as shown in Figure 18. In the meantime, the arms (12) of the stretcher (5) have been moved from their outer positions (14) to their inner positions (15). This repositions the hooks (13) to receive and stretch a next sleeve (9) for the carrying frame (5), to repeat the process with a next set of palletised bags (2A), as shown in Figures 20 and 21.

[0101] It will be appreciated that the embodiment described above is given by way of example only and is not intended to limit the scope of the invention. It is possible to alter aspects of the embodiment without departing from the essence of the invention.

[0102] It is for example possible to use frame of different dimensions and configurations. A square frame can be used for goods packed on a square pallet, a rectangular frame can be used for goods packed on a rectangular pallet, and a circular frame can be used for goods wrapping a right circular cylindrical stack or circular goods such as drums packed on a square shaped pallet.

[0103] The carrying frame may also include means to allow it to controllably collapse or close. This will allow the stretched sleeve to be released from the carrying frame at the election of the operator.

[0104] It will also be appreciated that the goods need not be covered only in the vertical direction. An item that may be gripped from one end and presented horizontally towards the manipulator can just as well be sealed from its free end using the system of the invention. This is done by rotating the carrying frame through 90°, instead of 180°, which allows it to be moved across the item that is packed in a horizontal direction instead of the vertical direction as described above. It is also possible to seal such an item part of its length, more than halfway, to swap the end from which it is gripped and seal it from the other end, with the item thus being sealed with two sleeves that overlap to completely seal the item.

[0105] Similarly, the specific positioning of the palletised goods is not critical. An alignment relative to some predetermined position is not required as is the case with conventional stretch hood wrapping systems. The manipulator can determine the orientation of the palletised goods, and operatively align the carrying frame accurately to it.

[0106] The installation of a system according to the invention is much simpler compared to prior art system. A stretcher is required which can be located and secured to any floor. The manipulator operates relative to it to locate the sleeve onto the carrying frame and can apply the sleeve all around it apart from where the stretcher is located. It is even possible for a single manipulator, especially an automated robotic version such as herein described, to have multiple stations around it where forklifts can deposit pallets for sealing.

[0107] Safety considerations dictate that these be placed within cages with doors that can close, but that as such does not limit the number of sealing bays around a single manipulator. Practically speaking, having 3 or even 5 bays around a single manipulator appears feasible.

[0108] This greatly increases the production capacity of the system with the manipulator being able to collect a stretched sleeve and seal one pallet which pone or more other pallets that have already been sealed are cleared from sealing bay, and a new pallet that is still to be sealed placed in position. The stretching frame can also be manufactured with the opening in the beam. The carrying frame can be extended beyond the hooks by means of a telescopic arm to collect the sleeve, the hooks can then be opened and one it has collected the sleeve the carrying frame can be lowered to below the stretcher again and withdrawn from it.

Claims

CLAIMS1 . A stretch hood wrapping system for an object, with the system including a stretcher, a carrying frame, and a manipulator that are configured to be operable to stretch wrap the object from a designated surface thereof with a hood comprising an elastic film sleeve, with the stretcher configured to stretch the sleeve, the carrying frame configured to receive the stretched sleeve from the stretcher, the manipulator being configured and operable to locate the carrying frame against a designated surface of the object and to pass the carrying frame over the object from its designated surface to proximate an opposing end thereof to stretch the sleeve over the object from its designated surface and along sides thereof, thereby allowing the sleeve to be transferred from the carrying frame onto the object to wrap the object from its designated surface and along its sides with a stretch hood.

2. A stretch hood wrapping system as claimed in claim 1 in which the elastic film sleeve has a sidewall that extends between an open end a closed end of the sleeve, and with the sidewall defining inside the sleeve a sleeve inner space on a cross-sectional plane that is normal to a longitudinal axis of the sleeve; with the stretcher including a plurality of grippers each being shaped and configured to releasable grip and stretch at least part of the sidewall for dimensions of the sleeve inner space to exceed dimensions of the designated surface of the object, with the sidewall being receivable substantially bunched-up on the grippers and the closed end of the sleeve extending between the grippers; with the carrying frame being shaped and configured to be securable to the manipulator, and having a continuous circumferential wall which defines a frame inner space on the operative inside of the wall that is complementary shaped to a shape of the designated surface of the object, and sized for dimensions of the frame inner space to exceed dimensions of the designated surface of the object; with the manipulator being configured and operable to locate the carrying frame against a designated surface of the object by - locating the carrying frame in a position between the grippers and inside the stretched and still bunched-up sidewall of the sleeve, moving the carrying frame against the operatively inner surface of the closed-end of the stretched sleeve to transfer the stretched and still bunched-up sidewall of the sleeve onto the outer surface of the carrying frame, therebytransferring the sleeve onto the carrying frame, with the still bunched-up sidewall of the sleeve located against an operatively outer surface of the carrying frame, and rotating the carrying frame to orientate the operatively outer surface of the closed end of the stretched sleeve to be coplanar with and facing the designated surface of the object.

3. A stretch hood wrapping system as claimed in claim 2 in which each gripper comprises an arm terminating in a hook with the hooks with the hooks of the plurality of grippers defining between them a stretching plane, with each arm being movable coplanar to the stretching plane between an inner position and an outer position, with the inner position of each arm being closer to a centre of the stretching plane than its outer position, operatively enabling the bunched-up sidewall of the sleeve to be located over the hooks with the arms located in their inner positions and to be stretched between the hooks with movement of the arms from their inner positions to their outer positions, to stretch the film between the hooks in the stretching plane.

4. A stretch hood wrapping system as claimed in claim 3 in which each hook terminates in an end that is provided with at least one roller.

5. A stretch hood wrapping system as claimed in claim 3 or 4 in which each arm is provided with a clamp terminating in an end that is provided with a roller guide, with each clamp being movable between a disengaged position in which the end of the clamp is distal from the hook and an engaged position in which the roller guide is located in abutment with the free of its respective hook against the roller on the end of the hook, in use against the bunched-up sidewall of the sleeve located on the hook.

6. A stretch hood wrapping system as claimed in claim 5 in which the clamp is secured to a cylinder that is operable between a compressed position in which the clamp is in the disengaged position and an extended position in which the clamp is in the engaged position.

7. A stretch hood wrapping system as claimed in any one of the preceding claims in which the carrying frame includes a base with a bracket shaped and configured to be securable to the manipulator.

8. A stretch hood wrapping system as claimed in any one of the preceding claims in which the circumferential wall of the carrying frame includes an operative top edge and an operative bottom edge, with a flange extending at least from proximate the bottom edge of the wall for at least part of the circumference of the wall and with the flange being directed outward from the wall.

9. A stretch hood wrapping system as claimed in claim 8 in which the top edge of the carrying frame is provided with a set of circumferential driven rollers, which are connected internally in the frame by means of drive shafts and gears at corners of the frame to at least one electrical motor.

10. A stretch hood wrapping system as claimed in claim 9 which includes a control system configured to determine the speed with which the manipulator passes the carrying frame over the object, for a processor associated with the control system to determine a complimentary speed of rotation for the rollers to ensure the stretched sleeve is transferred from the carrying frame at substantially the same rate that the manipulator passes the carrying frame over the object, and with control system being configured to control the electrical motors to drive the rollers at the complimentary speed of rotation.

11. A stretch hood wrapping system as claimed in any one of the preceding claims in which the designated surface of the object is on a free end of the object comprising its upper surface, and the object comprises a palletised product.

12. A stretch hood wrapping system as claimed in any one of claims 2 to 11 in which each arm of the gripper is slidingly movable between its inner position and its outer position.

13. A stretch hood wrapping system as claimed in any one of the preceding claims in which the stretcher preferably includes a set of legs supporting a stretcher frame, with the arms being movable secured to the stretcher frame.

14. A stretch hood wrapping system as claimed in any one of the preceding claims in which the manipulator comprises a programmable robot.

15. A carrying frame for a stretch hood wrapping system, with the frame being shaped and configured to be securable to a manipulator that is configured operatively to stretch wrap an object from a designated surface thereof with a hood comprising an elastic filmsleeve by passing the carrying frame carrying the sleeve bunched-up on the frame over the object; with the frame including a continuous circumferential wall which defines a frame inner space on the operative inside of the wall that is complementary shaped to a shape of the designated surface of the object, and which is sized for dimensions of the frame inner space to exceed dimensions of the designated surface of the object.

16. A carrying frame as claimed in claim 15 in which the circumferential wall of the carrying frame includes an operative top edge and an operative bottom edge, with a flange extending at least from proximate the bottom edge of the wall for at least part of the circumference of the wall and with the flange being directed outward from the wall.

17. A carrying frame as claimed in claim 16 in which the top edge of the carrying frame is provided with a set of circumferential driven rollers, which are connected internally in the frame by means of drive shafts and gears at corners of the frame to at least one electrical motor.

18. A method of wrapping an object with a stretch hood by locating a stretched sleeve over a carrying frame that is shaped and sized to have inner dimensions exceeding the outer dimensions of a designated surface of the object, orientating the operatively upper surface of the stretched sleeve to be coplanar with and face the designated surface of the object, passing the carrying frame over the object from its designated surface to proximate an opposing end thereof to stretch the sleeve over the object from its designated surface and along sides thereof, thereby allowing the sleeve to be transferred from the carrying frame onto the object, to wrap the product from its designated surface and along its sides with a stretch hood.

19. A method as claimed in claim 18 which includes determining the speed with which the manipulator passes the carrying frame over the object, determining a complimentary speed of rotation for a set of circumferential driven rollers on the top edge of the carrying frame, which are connected internally in the frame by means of drive shafts and gears at corners of the frame to at least one electrical motor, to ensure the stretched sleeve is transferred from the carrying frame at substantially the same rate that the manipulator passes the carrying frame over the object, and controlling the electrical motors to drive the rollers at the complimentary speed of rotation.

20. A stretch hood wrapping system substantially as herein described with reference to the drawings.

21. A carrying frame for a stretch hood wrapping system substantially as herein described with reference to the drawings.

22. A method of wrapping an object with a stretch hood substantially as herein described with reference to the drawings.

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