US20090202327A1

US20090202327A1 - Cylindrical module unwrapping device and method

Info

Publication number: US20090202327A1
Application number: US12/069,602
Authority: US
Inventors: Mark D. Cory; Roy Owens
Original assignee: Cherokee Fabrication Co Inc
Current assignee: Cherokee Fabrication Co Inc
Priority date: 2008-02-12
Filing date: 2008-02-12
Publication date: 2009-08-13

Abstract

A device and method for removing fibrous materials from a wrapped cylindrical module of fibrous material. The wrap material encloses the lateral sides of the cylindrical module, but only overlaps a portion of each end of the module. A cylindrical module is advanced on its side upon a conveyor to a loading position where it is lifted by one or more grasping members on one or more arms to an unloading position without altering the orientation of the module. The cylindrical module is then turned vertically to allow the fibrous material to fall out of the wrap material. The wrap material remains attached to the grasping member by a plurality of projections. Once empty, the empty wrap material may be manually removed and discarded and the arm returned to the loading position to lift the next module.

Description

FIELD OF THE INVENTION

This invention relates in general to processing fibrous materials, and in particular to a method and apparatus for removing a wrapping or cover from cylindrical modules of fibrous materials. While the invention may be useful for unwrapping modules of other fibrous materials, it has been developed for use in conjunction with cylindrical modules or bales of cotton wrapped in plastic film.

BACKGROUND OF THE INVENTION

Freshly picked seed cotton must be transported from the field where it has been picked to a cotton gin. Recent improvements to harvester technology have resulted in the popularity of cotton harvesters with on-board processing systems that create compacted cylindrical bales of seed cotton. In order to protect the cotton and to ease its transportation, current harvesters wrap the module in plastic sheet or netting material at least around the rounded sides (i.e., the curved surface of the cylinder) and typically with some overlap on the top and bottom. Cylindrical cotton modules, often called round modules, are wrapped in a wrapping material, such as plastic sheeting, polyethylene film or other netting material to protect and maintain the integrity of the formed module and to prevent water from wicking into the cotton. Such wrap material typically covers the cylindrical sides (or curved surface) of the module and part or all of one or more ends of the module so that water cannot enter the module when it is lying on its side on the ground, and thereby damage the cotton.
Current harvesters form the module by rolling and compacting the seed cotton. As the roll grows near its final diameter, a tail of the wrap material is incorporated into the roll to maintain the wrap around the roll as the final layer of the module is compacted. When the final layer of cotton being compacted sufficiently overlaps the tail section of the wrap material, the addition of cotton is halted and the wrap material is adhered to the under-laying wrapped material.
When handling wrapped modules, the processing system must be able to efficiently separate all of the cotton from the wrap material before the cotton enters the cotton gin. Many methods for unwrapping modules include slitting or cutting the wrap material. However, if not precisely controlled, such cuts may result in the tail of the wrap material remaining in the cotton and entering the gin. Such contaminated cotton is undesirable because it may foul the workings of the gin or later processing of the gin cotton into thread. Thread made with contaminated cotton is virtually unusable. Contaminated cotton is often rejected by the mill and returned to the grower or deeply discounted, resulting in expensive losses to the grower.
The cotton modules being manipulated can weigh several tons and have a diameter and a length on the order of eight feet or more. When the wrap material is removed, the cotton quickly loses its cylindrical shape, resulting in a mass of relatively loose cotton which can no longer practically be handled as a cohesive unit except by placing the entire pile of loose cotton on a conveyor.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an improved device for unwrapping cylindrical modules of fibrous materials.
Another object of the present invention is to provide an improved module unwrapping system and method which avoids contamination of the cotton by wrap material remnants.
A further object of the present invention is to remove the wrap material from a cylindrical fibrous module while keeping the wrap material in a single piece, thereby avoiding contamination of the cotton.
It is still other object of the present invention to provide a method for easily removing the wrap material from round modules while assuring complete removal of the cotton from the wrap.
Another object of the present invention is to provide a device for unwrapping cylindrical modules that will not prohibit the use of the same conveyor for the processing of standard rectangular modules.
In one embodiment, a pair of parallel arms affixed on either side of a module conveyor grasp the advancing, wrapped cylindrical module from either side, lift the cylindrical module and turn it into a vertical orientation, thereby allowing the weight of the cotton itself to pull the cotton out of the open-bottomed sheet of the wrap which is retained by spikes the arms. Once the cotton falls or is shaken out of the wrap material, the intact wrap material can be easily removed and discarded or recycled.
In another embodiment, the cylindrical module is advanced along a conveyor while laying on its side in between a pair of opposing vertical tracks upon which are slidably mounted a pair of opposing, inwardly facing lift units. When the cylinder is between vertical tracks, the lift units are pivoted to axially correspond to the cylinder and actuated to compress inward towards each other thereby grasping the cylinder. The lift units then travel up on the vertical tracks and then are pivoted 90 degrees so that the cylinder is turned to the vertical, thereby allowing the cotton to fall out of the open bottom of the wrap material while the wrap material itself is held in place by spikes on the inner surface of the lift units.

BRIEF DESCRIPTION OF THE DRAWINGS

The particular features and advantages of the invention as well as other objects will become apparent from the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a perspective view of a first embodiment of the cylindrical module unwrapping device of the present invention with the arms in the loading position.

FIG. 2 is a schematic view of a cross-section of a cylindrical or “round” module of fibrous material such as cotton.

FIG. 3 is a perspective view of a cylindrical module of fibrous material such as cotton.

FIG. 4 is a side view of a first embodiment of the cylindrical module unwrapping device of the present invention with the arms in the unloading position and the lift elements carrying a module.

FIG. 5 is a side view of a first embodiment of the cylindrical module unwrapping device of the present invention with the arms in the unloading position and the lift elements turning to unload the cotton from the wrap.

FIG. 6 is a side view of a first embodiment of the cylindrical module unwrapping device of the present invention with the arms in the unloading position and the lift elements carrying a module wherein the lift elements have been turned to unload the cotton from the wrap.

FIG. 7 is a perspective view of a grasping member of the cylindrical module unwrapping device of the present invention.

FIG. 8 is a side view of another embodiment of the cylindrical module unwrapping device of the present invention having a sturdier arm configuration.

FIG. 9 is a perspective view of another embodiment of the cylindrical module unwrapping device of the present invention having the lift element carried on a gantry.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As illustrated in FIG. 1, a module-receiving area 15 of a crop processing facility such as a cotton gin is shown. A plurality of wrapped bales, also called round modules 11, of fibrous material, such as seed cotton 14, are delivered by truck or other suitable transport vehicle (not shown) to a horizontal receiving conveyor 18. Cylindrical modules 11 are typically loaded on the conveyor 18 on their lateral or rounded side, i.e., the curved surface of the cylinder, with the vertical axis 25 of the cylindrical module 11 roughly parallel to the conveyor 18. The conveyor 18 moves the modules 11 laterally away from the transport vehicle towards the first component of the gin system such as disperser 20. A disperser 20 is typically the first element of a cotton gin line as its spiked, spinning, disperser cylinders 22 function to break up seed cotton modules 14.
The cylindrical module unwrapping device 10 of the present invention is located upstream of the disperser 20, preferably proximate to the end of the conveyor 18 where the conveyor 18 feeds seed cotton 14 into the disperser 20. The unwrapping device 10 is placed there for removing the wrap 30 from the modules 11 of seed cotton 14 prior to the entry of the cotton 14 into the disperser 20.
As shown in FIG. 1, the cylindrical module unwrapping device 10 comprises an arm structure, such as one or more powered arms 33 pivotably affixed along side said conveyor 18, such as to a base 36. If desirable, base 36 may alternatively be suspended, such as from the ceiling or other structural support (not shown). Preferably the device 10 comprises at least two arms 33, one on each opposing side 19 a, 19 b of the conveyor 18. A suitable mechanism 61 is provided for raising and lowering the arms 33 such as one or more hydraulic cylinders or a chain or belt drive and motor (not shown) or any other suitable mechanism.
Each such arm 33 has a base end 34 pivotably connected to base 36 and an opposed working end 35. Attached proximate to the working end 35 of each arm 33 is an inwardly-facing lift element 40. The lift element 40 is pivotably attached to the working end 35 of the arm 33 and may be hydraulically-actuated about the pivot point 37 by a suitable turning mechanism 63 for rotating the lift element 40 about the pivot point 37 such as one or more hydraulic cylinders or a chain belt and motor (not shown) or any other suitable mechanism.
The lift element 40 further comprises one or more hydraulically-actuated grasping members 44 for engaging the module 11. In a preferred embodiment, grasping members 44 further comprise one or more elongated plates 46, 47 attached to the lift element 40 and a suitable pushing mechanism 66 for pushing the grasping members 44 against the module 11 such as one or more hydraulic cylinders or any other suitable mechanism. The attachment of plates 46, 47 to lift element 40 may be made by one or more struts 49, 50.
A plurality of projections such as spikes 53, preferably tapered, extend from the inward surface 42 of plates 46, 47 for puncturing the wrap 30 and assisting in the lifting of the module 11. While any roughening of the inward surface 42 of the plates 46, 47 with assortedly shaped projections may provide adequate frictional gripping ability to lift a module 11, spikes 53 or other similar elongated projections are preferred in order to puncture the wrap material 30. Spikes 53 range from about 1 to about 10 centimeters in length and between about 0.3 to about 2 centimeters in diameter at the widest point. All or some of the spikes 53 are preferably oriented pointing slightly upward relative to the axis 25 of the cylindrical module 11 so that when the plates 46, 47 grasp the module 11 and the lift element 40 is actuated to turn the cylindrical module 11 vertically, (as shown in FIG. 6), the upward slant of the spikes 53 assist in keeping the wrap 30 engaged with the plates 46, 47 as the cotton 14 falls out of the wrap 30 onto the conveyor 18.
As shown in FIGS. 2 and 3, the generally cylindrical modules 11 include a wrap 30 shown as generally solid, continuous sheet of plastic material such as polyethylene or polypropylene that protects and maintains the integrity of the modules 11 during storage and transport to the gin, and handling at the gin. The wrap 30 is wound around the circumference of formed modules 11 of cotton 14, starting at a location or inner edge 30 a and terminating with more than one layer of wrap material at an end or outer edge 30 b. The end of the wrap 30 b is attached to the previous layer of wrap material by an area of tacky material or by any other suitable joining method such as stapling, taping, gluing, heat sealing or stitching. The wrap material itself will typically cling together wherever it overlaps itself without an intervening bat 16 of seed cotton 14. It is common for the wrap material 30 to be wound multiple times around the module 11 for strength.
As shown in FIG. 3, modules 11 are roughly cylindrical in shape and have a vertical axis 25 and a curved surface or side 23. The module wrap 30 is formed from a generally rectangular sheet of wrap material and is wrapped around the compacted cotton so that the inner edge 30 a is approximately parallel to the axis 25 of the module 11.
As previously discussed, as a module 11 of seed cotton 14 is formed in the harvester (not shown), a tail 31 of wrap material 30 on the inside of the wrap 30 is left embedded within the cotton 14 of the module 11 so that it is not adhered or adhesively secured to a portion 32 of the wrap 30 which overlays the intervening bat 16 of cotton 14 over the tail 31. The length of the tail 31 may vary widely based on the type of module builder used. It may also be that tails 31 are formed within the cotton in various other manners during the formation and wrapping of the module 11.
As shown in FIG. 3, an overlapping portion 28 of the wrap material 30 generally overlaps at least a first or top end 12 of the module 11 and a second overlapping portion 27 of wrap material 30 may also overlap a second or bottom end 13 of the module 11 to prevent water from wicking up into the seed cotton 14 when the module 11 is laying on its side 23 (i.e., the curved surface of the cylinder). In current practice, the overlapping portions 27, 28 of wrap 30 overlap between about 15 to about 31 centimeters of each end 12, 13.
Returning, then, to FIG. 1, cylindrical modules 11 are typically transported lying on the side 23 and loaded onto a conveyor 18 in that same orientation upon arrival at a gin. The cylindrical module unwrapping device 10 of the present invention is shown with the module 11 having been advanced on its side 23 upon conveyor 18 to a first position adjacent and between the working ends 35 of the arms 33 when the arms 33 are lowered to a loading position. The lift element 40 of each arm 33 is rotated to orient so that it is aligned with the axis 25 of the cylindrical module 11 and the grasping members 44 actuated from either side of the conveyor 18 to grasp the cylindrical module 11 at points on substantially opposite sides of the module 11. When the grasping members 44 are actuated towards the module 11, the spikes 53 of the plates 46, 47 puncture through the wrap 30 and embed into the cotton 14 of the module 11. The frictional pressure generated by the inward pressing of the plates 46, 47 of the grasping members 44, along with the added gripping force of the spikes 53, allow the module 11 to be squeezed between the lift elements 40 of the opposing arms 33 and lifted.
Installation of the cylindrical module unwrapping device of the present invention will have no effect upon the ability to continue to process standard rectangular modules (not shown) using the conveyor 18 and disperser 20 as the arms and lift elements can be configured to allow such standard rectangular modules (not shown) pass by the device 10 on the conveyor 18 without inhibition.
As shown in FIG. 4, the arms 33 are then raised to a second, unloading position, thereby lifting the module 11 off of the conveyor 18 and holding it above the conveyor 18. Preferably, when the module 11 is raised to the unloading position, it will be above a portion of the conveyor 18 proximate to and immediately upstream of the disperser 20 at a point where the conveyor 18 has been bounded on either side by opposing retaining walls 59 and 58 (wall 58 not shown in FIG. 4). The retaining walls 59 and 58 serve to assist in keeping the cotton 14 on the conveyor 18 when, as shown in FIGS. 5 and 6, the lift element 40 is rotated so that the axis 25 of the cylinder is brought to vertical (that is perpendicular to the conveyor 18 if the conveyor is level) thereby allowing the cotton 14 to fall out of the wrap 30.
The retaining walls 59 and 58 (not shown) may be slanted inward from top to bottom to assist in guiding the cotton 14 from the modules 11 onto the conveyor 18.
As shown in FIG. 4, in order to keep the cotton 14 from falling out of the wrap 30 prematurely, it is preferred that the lift elements 40 be configured to maintain the orientation of the module 11 relative to the conveyor 18 while the arms 33 are being lifted from the loading position to the unloading position. In other words, while the arms 33 are being raised, the lift element 40 is rotated at a rate which maintains the axis 25 of the cylindrical module 11 substantially parallel to the conveyor 18. Once the arms 33 are raised to the unload position, the module 11 is rotated by rotating the lift elements 40 to bring the axis 25 of the module 11 perpendicular to the conveyor 18. It has been found that the weight of the cotton 14 within the wrap 30 is itself heavy enough to cause the compacted cotton 14 to fall out of the wrap 30 when the module 11 is held vertically, despite the presence of any overlapping portions 27, 28 of the wrap 30. However, it may be desirable to configure either the arms 33 or the lift elements 40 to shake the modules 11, preferably in an up and down motion, to assist in the complete removal of the cotton 14 from within the wrap 30. Conceivably, a blower mechanism (not shown) may also be utilized to assist in the complete removal of the cotton 14 from the wrap 30. Depending on the width of the overlapping portions of the wrap 30, it may also be desirable to provide a mechanism for creating one or more radial cuts or perforations (not shown) in the width of the overlapping portions 27, 28 of the wrap 30 on one or both ends 12, 13.
Because the tail 31 of the wrap 30 is merely compacted into the cotton 14 of the modules 11, when the cotton 14 falls out of the wrap 30, it separates from the inner walls 29 of the wrap 30 and from the tail 31, leaving all of the wrap material 30 in a single piece which is held above the conveyor 18 on the spikes 53 of the lift elements 40. The strength of the wrap material 30 coupled with the expansion and loss of integrity of the compacted cotton 14 as it falls out of the wrap 30 result in very low likelihood that all or part of the tail 31 or surrounding portions of wrap material 30 will be torn away from the wrap 30 to contaminate the cotton 14.
Once the wrap 30 is emptied of cotton 14, the wrap 30 is removed from the lift elements 40. To assist in the wrap 30 removal, the lift elements 40 may be rotated 180 degrees so that the spikes 53 on the lift elements 40 are pointing downward, making it easier for the wrap material 30 to be pulled off of, or perhaps even fall or be shaken off of, the lift element 40. Once removed, the used wrap material 30 may be discarded or recycled.
As shown in FIG. 7, the plates 46, 47 of the grasping members 44 of lift elements 40 may be fitted with a press plate 65 having a plurality of perforations 64 in a pattern and shape corresponding to the spikes 53. A press plate 65 is operatively connected to each plate 46, 47 and has a normal position substantially flush against the inward surface 42 of plate 46 or 47 with each spike 53 extending through a corresponding perforation 64. The press plate 65 may be actuated to extend away from the plate 46, 47 to which it is connected a distance substantially the same as the length of the spikes 53 to push any wrap material 30 or clinging clumps of cotton 14 off of the spikes 53. If necessary, the perforations 64 may be oblong to accommodate the tilt of the spikes 53 when the press plate 65 is in both the normal and extended positions. A suitable press mechanism 55 is provided for shifting the press plate 65 between its normal and extended positions, such as one or more hydraulic cylinders or pneumatic cylinders or any other suitable mechanism.
Returning to FIG. 6, once the unbaled cotton 14 is loaded onto the conveyor 18, it is fed by the conveyor 18 into the disperser 20 to begin the ginning process. As the conveyor 18 feeds the unbaled cotton into the disperser 20, the conveyor 18 is also advancing the next round module 11 to the loading position to which the arms 33 are lowered. Once between the lowered arms 33, the inwardly-facing lifting elements 40 will grasp the next module 11 to begin the next unwrapping operation. The timing of the movement of the conveyor 18 and the lifting and unloading of the modules may be adjusted and coordinated to yield a relatively constant volume of cotton 14 being fed into the disperser 20.
Turning then to FIG. 8, a second preferred embodiment of the cylindrical module unwrapping device 10 of the present invention is depicted. As illustrated, the arms 33 on either side of the conveyor 18 may comprise a plurality of arm posts 70, 71 to add strength to the device 10. Each arm post 70, 71 is joined to the other arm post 70, 71 by one or more rigid spacers 69 connected at opposing ends 72, 73 to the arm posts 70, 71 at a connection, such as rotatable connection 74, capable of allowing the spacer 69 to move relative to the arm post 70, 71 as the arms 33 are raised and lowered. Thus it can be seen that as the arm posts 70, 71 are raised and lowered, they remain held parallel to each other by the spacers 69.
In this preferred embodiment, the lift elements 40 of each opposing arm 33 are pivotally attached to a pivot point 37 on one of the spacers 69.
If both this and the earlier embodiment, if desired, the working end 35 the arms 33 can be lengthened beyond the point of attachment 37 of the lift elements 40 so that the two opposing arms 33 on either side of the conveyor 18 can be joined by a one or more cross pieces 77, 78 to strengthen and add rigidity to the device 10 and ensure that the opposing arms 33 always move in parallel. If such connection between the arms 33 by cross pieces 77, 78 is desired, care must be taken to ensure that the arms 33 are sufficiently lengthened past the pivot point 37 so that the cross pieces 77, 78 do not interfere with the rotation of a module 11 when it is grasped and rotated by the lift elements 40.
A third embodiment of the present invention is depicted in FIG. 9. In this embodiment, the lift elements 40 are carried on vertical tracks 81, 82 attached to bases 85, 86 (not shown). The vertical tracks 81, 82 may be sturdy enough to lift modules 11 themselves, or may be mounted to a support structure such as towers 88, 89. The support structure may be fixed by attachment to a base (not shown) or it may comprise a mobile support structure such as wheeled gantry 92, tracks 93 and a suitable mechanism for moving the gantry 92 upstream and downstream along the path of the conveyor 18, such as one or more hydraulic cylinders, electric motors or any other suitable mechanism. Tracks 93 are preferably located on either side of the conveyor 18 outside of retaining walls 58, 59 so that loose cotton 14 does not interfere with the operation of the tracks 93. Another alternative is to have the gantry 92 carried above the conveyor along one or more suspended rails (not shown).
Thus, it can be seen that the round module 11 is carried by the conveyor 18 to a loading position between the tracks 81, 82 where it is grasped by the lift elements 40 and lifted as the lift elements 40 are raised up the tracks 81, 82 by a lifting mechanism 95 for raising and lowering the lift elements 40 along the vertical tracks 81, 82, such as one or more hydraulic cylinders or a chain or belt drive (not shown) or any other suitable mechanism. When sufficient height to allow the complete emptying of the cotton 14 from the wrap 30 has been obtained, the lift elements 40 are rotated to bring the axis 25 of the cylindrical module 11 to vertical so that the cotton 14 can fall out of the wrap 30.
The configuration shown in FIG. 9 may be less preferred because since the lift elements 40 must run up and down the vertical tracks 81, 82, when the cotton 14 escapes the confines of the wrap 30, it may fall onto or in amongst the tracks 81, 82, potentially clogging or otherwise interfering with the operation of the device.
Although this invention has been disclosed and described in its preferred forms with a certain degree of particularity, it is understood that the present disclosure of the preferred forms is only by way of example and that numerous changes in the details of operation and in the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

Claims

1. A device for removing fibrous materials from a module of fibrous material having a wrap material enclosing the sides of the module, said device comprising:

(a) one or more arm structures pivotably affixed at a base end along side a conveyor of such modules, said arm structure having a working end opposite the base end, said working end positionable between a loading position and an unloading position;

(b) said arm structure having a lift element for engaging the sides of a module lying on the conveyor, said lift element pivotably attached at a pivot point to said arm structure proximate the working end of said arm structure.

2. The device of claim 1 wherein said arm structure further comprises a pair of arms, one of each such arms affixed opposite the other arm on opposing sides of the conveyor.

3. The device of claim 1 wherein the lift element further comprises one or more grasping members for engaging the module.

4. The device of claim 3 wherein said grasping member comprises one or more plates having a plurality of projections upon an inward surface of said plate.

5. The device of claim 4 wherein said projections comprise spikes for puncturing the wrap material.

6. The device of claim 1 further comprising a mechanism for raising and lowering said arm structure between said loading position and said unloading position.

7. The device of claim 1 further comprising a turning mechanism for rotating said lift element about the pivot point.

8. The device of claim 3 further comprising a pushing mechanism for pushing the grasping member against the module.

9. The device of claim 2 wherein said arms are joined by a cross piece.

10. The device of claim 2 wherein each of said arms further comprise a plurality of parallel arm posts joined by spacers.

11. A method of removing fibrous materials from a cylindrical module of fibrous material having a wrap material enclosing a curved surface of the module, said module having a vertical axis, said method comprising the steps of:

(a) loading a module on its curved surface upon a conveyor;

(b) advancing the module upon the conveyor to a loading position;

(c) engaging the curved surface of the module;

(d) lifting the module to an unloading position above the conveyor while maintaining the vertical axis of the module substantially parallel to the conveyor;

(e) turning the module to bring the vertical axis of the module to a vertical orientation so that the fibrous material falls out of the wrap material onto the conveyor.

12. The method of claim 11 wherein said engaging step further comprises puncturing the wrap material with a plurality of spikes to assist in retaining the wrap material as the fibrous material is unloaded during the turning step.

13. The method of claim 11 wherein the loading position is adjacent one or more arm structures pivotably affixed at a base end along side the conveyor, said arm structure having a working end opposite the base end, said working end positionable between the loading position and the unloading position.

14. The method of claim 13 wherein the arm structure further comprises a lift element for engaging the curved surface of the module, said lift element pivotably attached at a pivot point to said arm structure proximate the working end of said arm structure.

15. The method of claim 11 wherein the engaging step further comprises engaging the curved surface of the module from substantially opposite sides of the module.

16. A device for emptying fibrous materials from within a wrapping enclosing the curved surface of a compacted module of fibrous materials, said device comprising:

(a) a first arm structure pivotably affixed at a base end along a first side of a conveyor of such modules, said first arm structure having a working end opposite the base end, said first arm structure being moveable between a loading position and an unloading position;

(b) a second arm structure pivotably affixed at a base end opposite the first arm structure along a second side of the conveyor, said second arm structure having a working end opposite the base end, said second arm structure being moveable between a loading position and an unloading position;

(c) a first lift element carrying one or more plates for pressing against the curved surface of the module, said lift element pivotably attached at a pivot point to said first arm structure;

(d) a second lift element carrying one or more plates for pressing against the curved surface of the module, said lift element pivotably attached at a pivot point to said second arm structure.

17. The device of claim 16 wherein said plates further comprise a plurality of projections upon an inward surface.

18. The device of claim 17 wherein at least some of said projections comprise spikes for puncturing the wrapping.

19. The device of claim 18 wherein said spikes are between about 1 centimeter to about 10 centimeters in length and between about 0.3 centimeters to about 2 centimeters in diameter at a widest point.

20. The device of claim 16 wherein the first arm structure and the second arm structure are joined by a cross piece.