AU700740B2

AU700740B2 - Film wrapping apparatus and method

Info

Publication number: AU700740B2
Application number: AU17615/95A
Authority: AU
Inventors: Yoshitaka Okuse; Ken Peters; Paul Rakich
Original assignee: TKK ENGINEERING Pty Ltd
Current assignee: TKK ENGINEERING Pty Ltd
Priority date: 1994-04-22
Filing date: 1995-04-21
Publication date: 1999-01-14
Anticipated expiration: 2015-04-21
Also published as: AU1761595A

Description

2 FILM WRAPPING APPARATUS AND METHOD FIELD OF THE INVENTION The present invention relates to a wrapping apparatus and method for wrapping a product in a web of plastic film and relates particularly, though not exclusively, to a hay bale wrapping apparatus and method for wrapping hay bales for export.

BACKGROUND TO THE INVENTION Australia has for many years been exporting hay to overseas countries, mainly for use as livestock fodder. In order to export the hay in a cost-effective manner it is compressed into bales which are then typically packed into shipping containers. The compressed bales are normally bound with twine or steel straps to retain their compressed shape.

S. 15 However, there are a number of disadvantages with this form of packing and shipping. Twine is not strong enough to inhibit expansion of the compressed hay and therefore the degree of compression is limited by the strength of the twine. Steel straps do not suffer from this problem, however 20 they are more difficult to remove by the farmer or other end i ouser. Furthermore, if any pieces of steel strap become mixed up with the hay, they may be consumed by livestock presenting a serious threat to the health of the animal if not fatal.

A further disadvantage is that a significant quantity of hay breaks away or falls off the bales during handling and transport. This not only creates a problem of uncleanliness s but may also result in substantial wastage of hay.

SUMMARY OF THE INVENTION The present invention was developed with a view to providing a way of packaging and shipping hay bales that is less susceptible to the problems noted above. However, it will be evident that the wrapping apparatus and method of the invention can be used for wrapping other products apart from hay bales and therefore the invention i alot limited in its r 1; ii:_ 3 4 application to wrapping hay bales.

According to one aspect of the present invention there is provided a wrapping apparatus for wrapping compressed hay into bales with a web of plastic film, the apparatus comprising: a rotatable ring member having a central axis about which the ring member is adapted to rotate; a plurality of film web dispensing means rotatably mounted at spaced locations about a circumference of said rinq member and adapted to dispense a corresponding plurality of film webs for wrapping the compressed hay as the ring member rotates; a chute substantially aligned with said central axis of the ring member and adapted to feed said compressed hay through said ring member, and wherein the end of said chute extends into a path of said plurality of film webs as they are dispensed, wherein a portion of the end of said chute is also wrapped by said plurality of film webs whereby, in use, as the compressed hay emerges from the end of said i 20 chute it pulls the film from the chute to inhibit expansion of the compressed hay as it emerges; and a guillotine for pre-cutting said compressed hay within said chute prior to wrapping whereby the compressed hay forming each bale is cut into sections.

0 25 Preferably each of said film web dispensing means o.comprises a roll of film rotatably mounted on the *0O circumference of said ring member and a plurality of rollers 9S*~r* S"adapted to feed the film from the roll to the product to be S• wrapped, at least one of said rollers being arranged to prestretch the film prior to wrapping about said product whereby, in use, the film webs provide a containment force about the product. Typically said, web of plastic film is a stretchable cling wrap film.

Preferably said plurality of rollers comprises a 4 pre-stretch drive roller, a floating pre-stretch driven roller and a fixed tracking roller, wherein said pre-stretch drive roller drives said pre-stretch driven roller via a drive transmission.

Preferably said drive transmission provides a gear ratio between said pre-stretch drive roller and pre-stretch driven roller that causes the pre-stretch driven roller to rotate faster than the pre-stretch drive roller whereby, in Suse, the film is pre-stretched as it passes therebetween.

Advantageously said ring member has four film web dispensing means rotatably mounted thereon. Typically the ring member is driven at a speed in the range of 30 to revolutions per minute (rpm), more preferably 50 to 75 rpm.

Preferably the apparatus further comprises: a second rotatable ring member also adapted to rotate about said central axis, and through which the product passes after it has been wrapped; and, o° a cutting means mounted on saA second ring member and adapted to cut the film webs wrapped about the product at 20 pre-determined intervals.

eo Typically the cutting means comprises a knife which cuts through the film web circumferentially about the product each time a pre-determined length of wrapped product has passed through said second ring member.

According to another aspect of the present S° invention there is provided a method of wrapping compressed hay into bales with a web of plastic film, the method 4* S.comprising the steps of: ejecting compressing hay from a chute so that it passes through a rotatable ring member along a central axis; revolving the ring member about said central axis; dispensing a plurality of film webs as the ring member rotates whereby, in use, as the compressed hay emerges from an end of said chute it is wrapped in said plurality of film webs; pre-cutting said compressed hay prior to ejection from the chute whereby the compressed hay forming each bale can be cut into sections; and, wherein said dispensing step involves dispensing the film webs so that a portion of the end of said chute is also wrapped by said plurality of film webs whereby, in use, as the compressed hay emerges from the end of said chute it pulls the film from the chute to inhibit expansion of the compressed hay as it emerges.

Preferably the plastic film is a stretchable cling wrap film and the method further comprises the step of: pre-stretching the film webs prior to wrapping about the product whereby, in use, the film webs provide a containment force about the product.

Advantageously the step of dispensing comprises *simultaneously dispensing four film webs as the ring member rotates.

o' According to a still further aspect of the oo a, O? 0o a o •7 o 6 invention there is provided a hay bale wrapped in a web of plastic film in accordance with the method of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In order to facilitate a better understanding of the nature of the invention a preferred embodiment of the wrapping apparatus and method will now be described in detail, by way of example only, with reference to the accompanying drawings in which: r Figure 1 is a schematic end view of a first ring 4. i0 member in the wrapping apparatus of the preferred embodiment; 444044 4 4 o ~Figure 2 is a schematic end view of a second ring o o0 member in the wrapping apparatus of the preferred embodiment; o 0 o o. Figure 3 is a schematic side view of the wrapping o. apparatus of the preferred embodiment; and, oa. 15 Figure 4 illustrates a hay bale wrapped by the o apparatus of Figures 1 to 3.

er 4 4: DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

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Referring to Figures 1 to 3 of the accompanying drawings, the preferred embodiment of the invention in the form of a hay bale wrapping apparatus 10 for wrapping compressed hay into bales is illustrated. The hay is subjected to approximately 200 tonnes of pressure in a press, S(not illustrated) and the compressed hay is ejected from the press via a chute 12 of rectangular cross-section. The inside dimensions of the chute are sized so that as the hay emerges from the end 14 of the chute it conforms to a standard bale size, having side walls approximately 36 centimetres high and top and bottom walls approximately centimetres wide.

As the compressed hay emerges from the end 14 of L 7 -7chute 12 it passes through a first rotatable ring member 16 along a central axis 18 about which the ring member 16 rotates. As can be seen most clearly in Figure i, the ring member 16 has four film web dispensing means 20 rotatably mounted at spaced locations about its circumference. The film web dispensing means 20 are adapted to dispense a corresponding plurality of film webs 22 as the ring member 16 rotates, so that as the compressed hay emerges from the chute 12 and passes through the rotating ring member 16 it is simultaneously wrapped in four film webs 22.

Each of the film web dispensing means 20 comprises a roll 4 of film rotatably mounted on the circumference of the ring member 16 and a plurality of rollers 1, 2 and 3 *4o.

adapted to feed the film from the roll 4 to the hay bale.

The web of plastic film employed for wrapping the hay bales :is typically manufactured from stretch-wrap plastics material, for example polyethylene film of relatively low linear density and having a cling additive. The feed rollers 1, 2 and 3 of the film web dispensing means 20 are arranged to pre-stretch the film prior to wrapping about the compressed hay so that the film webs provide a containment force about the compressed hay.

In this embodiment the plurality of feed rollers comprise a pre-stretch drive roller 1, which is in rolling engagement with the outer circumference of the film roll 4, a pre-stretch driven roller 2 which is driven by the drive roller 1 via a drive transmission (not illustrated), and a fixed tracking roller 3 which ensures that the film webs 22 are properly aligned as they are dispensed onto the compressed hay during rotation of ring member 16. The drive transmission that mechanically couples the pre-stretch drive roller 1 and the pre-stretch driven roller 2 is typically a chain with sprockets having a gear ratio of 36:13 so that the driven roller 2 rotates almost three times as fast as the drive roller 1. In this way, the film 22 is pre-stretched at

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r* .4 4 4 4 I 4 8 a pre-stretch ratio in the range of approximately 1.5:1 to 3.5:1. Some further stretching of the film webs 22 may occur between roller 2 and the compressed hay 15. The tracking roller 3 is also provided with anti-static means to inhibit the build-up of static charge on the film webs 22.

Pre-stretch rollers 1 and 2 are mounted on a common support assembly (not illustrated) which is pivotally connected to the ring member 16 by a hinge pin 26. The support assembly for rollers 1 and 2 is biased by a spring (not illustrated) which keeps the pre-stretch drive roller 1 in constant contact with the outer surface of the film roll 4. In use, as the first ring member 4 rotates the four webs of film wrap are drawn from each of the film rolls 4 due to the tensile forces acting through the film webs 22 between the compressed hay 15 and the rolls 4. The tensile forces are such that the webs of film are stretched almost to their limit, so that as the compressed hay is wrapped in the film webs very little expansion of the compressed hay can occur due to stretching of the film webs.

In this embodiment the first ring member 16 is in the form of a slew ring, which is a ring gear having gear teeth on its outer periphery that engage with a relatively small drive gear connected to the shaft of a variable speed electric motor (not illustrated). Typically the ring member 16 is driven at a speed in the range of 30 to 90 revolutions per minute, more typically in the range 50 to 75 rpm.

Because the hay bale wrapping machine lays down four layers of stretch wrap simultaneously by the four film web dispensing means 20, a speed of 50 rpm for ring member 16 is equivalent to a speed of 200 rpm for a ring member carrying only one film web dispensing means.

The end 14 of the chute 12 is arranged so that it extends through the first ring member 16 into the region between the film rolls 4 so that as the film layers are -9dispensed a portion of the end of chute 12 is also wrapped by the four film webs. This is to ensure that the compressed hay is wrapped in the film webs immediately it emerges from the end 14 of the chute and therefore expansion of the compressed hay as it emerges is inhibited. As the compressed hay emerges from the end of the chute it drags the film with it from off the end of the chute. Of course, as quickly as the film is pulled off the end of the chute, it is replaced by new layers of film from the foi:r film dispensing means 1 0 Due to the high pressures exerted on the compressed o mhay a layer of vegetable matter and cellulose rapidly builds up on the inner surfaces of the ejection chute 12, inhibiting eoro t :o the smooth and efficient ejection of the compressed hay from the end 14 of the chute. In order to inhibit this build-up of cellulose, the inner surfaces of the chut"E' 2 are lined with a polyethylene wear plate to minimise friction and promote free sliding of the compressed hay through the chute 12. The thickness of the polyethylene lining on the sidewalls of the chute is approximately 5mm, whereas on the top and bottom walls it is approximately 3mm thick.

a g. :Means for cutting the compressed hay within the chute 12 may be provided in the form of a guillotine 50 to enable the bales to be pre-cut into sections prior to wrapping. Guillotine 50 comprises a thin guillotine blade 52 slidably mounted within a stand 54 and driven in a vertical direction by a double-acting hydraulic ram 56. Ram 56 moves rapidly and forces the blade 52 through the compressed hay in a single stroke, then immediately returns to its retracted position. Travel of the compressed hay through chute 12 is momentarily halted during operation of guillotine Preferably guillotine 50 is activated every time ejection of compressed hay from chute 12 is halted during cutting of the layers of film wrap at the exit of the wrapping apparatus, as described below. The guillotine stand 54 is preferably positioned relative to the end 14 of chute 12 such that each 10 bale is cut through the middle to form two half bales, which are then wrapped as a single bale. If the end-user, for example, a farmer, finds the single bales are too heavy to handle manually, he can cut the bale in half simply by cutting through the layers of filmn wrap on a circumferential line around the middle of the bale. The two halves of the bale will then fall apart as the bale has been pre-cut.

The wrapping apparatus 10 further comprises a second rotatable ring member 30 (see Figure which also rotates about the central axis 18 and through which the compressed hay passes after it has been wrapped. A cutting means 32 is mounted on the ring member 30 and is arranged to oocut the film webs 22 wrapped about the compressed hay at predetermined intervals, so as to form individual hay bales 34.

Cutting means 32 comprises a knife 36 mounted on a support arm 38 which is pivotally connected to the second ring member A small jockey wheel 40 is rotatably mounted adjacent the knife 36 and is adapted to ride over the outer surface of the compressed hay bale 34 as the knife 36 cuts through the webs of film. A pneumatic ram 42 actuates support arm 38 so that it moves from a retracted position to a cutting position in which the jockey wheel 42 rides on the outer surface of the hay bale.

Both the first and second ring member 16, 30 are -otatably mounted on a rigid steel support frame 44 designed to inhibit vibration and control harmonics. The second ring member 30 is driven in a similar manner to that of the first ring menmber 16, but is driven independently thereof.

Furthermore, the second ring member 30 is provided with a rotation sensing means that generates a pulse train so that the position of the knife 36 and the number of revolutions of the second ring member 30 can be monitored and controlled.

The steel support frame 44 is also provided with a support tray 46 arranged to support the compressed hay after it has been wrapped and prior to cutting of the film wrap with knife

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11 36. The distance A between the plane of rotation of knife 36 and th plane of rotation of the centres of the film rolls 4 is approximately equal to twice the length of one hay bale 34, ie, approximately 1 metre.

The operation of the wrapping apparatus 10 is controlled by means of a programmable logic controller (PLC) accord 4 ng to the following control sequence. Compressed hay emerges from the eject chute 12 at a rate of approximately 6 metres per minute. The speed of the first ring member 16 is S 10 matUched to the linear speed of the compressed hay to produce o" a spiral wrap of the film webs about the compressed hay.

99*99* As the compressed hay begins to emerge from the chute 12 the ring member 16 begins to rotate and lay approximately 100mm of stretch film over the end 14 of the 0 -o 15 chute. During initial set-up the wrapping process will be r maintained continuously until approximately 1.5 metres of compressed hay have been continuously wrapped. However, at that point when the full length of one bale has moved beyond 9499 the plane of rotation of blade 36, (approximately 49cm) the 20 first ring member 16 stops rotating and ejection of S",3 compressed hay from the chute 12 is momentarily stopped, so that the first bale can be cut.

The second ring member 30 is then rotated and pneumatic ram 42 actuated so as to bring jockey wheel 40 into rolling contact with the outer surface of the wrapped compressed hay. Knife 36 then cuts through the layers of film wrap and the first hay bale 34 separates from the bulk of the compressed hay under its own weight. An example of a wrapped hay bale 34 is illustrated in Figure 4. The dimensions of the hay bale 34 are approximately 40 x 36 x 49cm. A single hay bale typically weighs between 30 to kilograms depending upon the pressure exerted in the press.

At the same time that ejection of hay from chute 12 t

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mA 12 is momentarily stopped and rotation of the second ring member commences, guillotine 50 is activated to cut through the compressed hay in chute 12. Therefore the length of compressed hay that passes the chute 12 between operations of S the guillotine 50 is equal to the full length of a hay bale.

However, as noted above, guillotine 50 is located at a prescribed distance from the end 14 of chute 12 such that it cuts through the middle of each wrapped bale that is cut by knife 36 at the exit of the wrapping apparatus 10 When the hay bale has been cut, rotation of the ooe second ring member 30 ceases and rotation of the first ring Oa member 16 recommences at the same time as ejection of compressed hay from chute 12 recommences. With the first ring member 16 rotating at up to 75 rpm, each bale receives approximately 15 wraps from each of the film rolls 4, or approximately 100 metres (25 metres x 4) of film wrap.

Wrapping and cutting of each hay bale is completed in approximately 40 seconds giving a rate of 90 wrapped hay bales per hour.

20 From the above description of the preferred embodiment of the wrapping apparatus and method according to the invention it will be evident that hay bales wrapped in this manner are substantially cleaner and easier to handle than hay bales wrapped in the conventional manner. A significant advantage of the wrapping apparatus and method of the invention is that the use of multiple film web dispensing means on a single rotatab3e ring member allows high speed wrapping of product with a plurality of film webs. This is especially important for compressed hay which expands rapidly if not contained. The simultaneous dispensing of multiple film webs as the product passes through the ring member can ensure that the required containment force is provided about the product without reducing the throughput of product to an unacceptably low level. Furthermore, the plastic stretch wrap is easily removed by the end user by employing a sharp 13 knife, and can be readily recycled if desired.

Numerous variations and modifications to the described embodiment will suggest themselves to persons skilled in the mechanical arts, in addition to those already described, without departing from the basic inventive concepts. In the preferred embodiment four film web dispensing means are employed on the ring member, however clearly the number of film web dispensing means may be two or more depending on the application. All such variations and modifications are to be considered within the scope of the present invention, the nature of which is to be determined O ofrom the foregoing description and the appended claims.

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Claims

1. A wrapping apparatus for wrapping compressed hay into bales with a web of plastic film, the apparatus comprising: a rotatable ring membr having a central axis about which the ring member is adapted to rotate; a plurality of film web dispensing means rotatably mounted at spaced locations about a circumference of said ring member and adapted to dispense a corresponding plurality of film webs for wrapping the compressed hay as the ring member rotates; a chute substantially aligned with said central axis of the ring member and adapted to feed said compressed hay through said ring member, and wherein the end of said chute extends into a path of said plurality of film webs as they are dispensed, wherein a portion of the end of said chute is also wrapped by said plurality of film webs whereby, in use, as the compressed hay emerges from the end of said chute it pulls the film from the chute to inhibit expansion 20 of the compressed hay as it emerges; and a guillotine for pre-cutting said compressed hay within said chute prior to wrapping whereby the compressed oo* hay forming each bale is cut into sections. o8

2. A wrapping apparatus as defined in claim 1, wherein each of said film web dispensing means comprises a roll of film rotatably mounted on the circumference of said ring member and a plurality.of rollers adapted to feed the film from the roll to the product to be wrapped, at least one of Ssaid rollers being arranged to pre-stretch the film pri( to wrapping about said product whereby, in use, the film webs ".provide a containment force about the product.

3. A wrapping apparatus as defined in claim i, wherein said chute has inside dimenisions sized so that as the hay j'1 emerges from the end of the chute it conforms to a standard 15 hay bale size.

4. A wrapping apparatus as defined in claim 2, wherein said plurality of rollers comprises a pre-stretch drive roller, a floating pre-stretch driven roller and a fixed tracking roller, wherein said pre-stretch drive roller drives said pre-stretch driven roller via a drive transmission. A wrapping apparatus as defined in claim 4, wherein said drive transmission provides a gear ratio between said pre-stretch drive roller and pre-stretch driven roller that causes the pre-stretch driven roller to rotate faster than the pre-stretch drive roller whereby, in use, the film is pre-stretched as it passes therebetween.

6. A wrapping apparatus as defined in claim 5, wherein said ring member has four film web dispensing means rotatably mounted there< n.

7. A wrapping apparatus as defined in claim 6, further comprising: a second rotatable ring member also adapted to S: 20 rotate ;about said central axis, and through which the product S* passes after it has been wrapped; and, a cutting means mounted on said second ring member and adapted to cut the film webs wrapped about the product at i ,pre-determined intervals. 25 8. A wrapping apparatus as defined in claim 7, wherein S"the cutting means comprises a knife which cuts through the film web circumferentially about the product each time a pre- determined length of wrapped product has passed through said second ring member.

9. A wrapping apparatus as defined in claim 3, wherein said guillotine is positioned relative to the end of the A! chute such that each bale is cut through the middle to form DFIF :-B)l.llprmTW*-UIC~ 16 two half bales, which are then wrapped as a single bale. A method of wrapping compressed hay into bales with a web of plastic film, the method comprising the steps of: ejecting compressing hay from a chute so that it passes through a rotatable ring member along a central axis; revolving the ring member about said central axis; dispensing a plurality of film webs as the ring member rotates whereby, in use, as the compressed hay emerges from an end of said chute it is wrapped in said plurality of film webs; pre-cutting said compressed hay prior to ejection from the chute whereby the compressed hay forming each bale can be cut into sections; and, wherein said dispensing step involves dispensing the film webs so that a portion of the end of said chute is also wrapped by said plurality of film webs whereby, in use, as the compressed hay emerges from the end of said chute it pulls the film from the chute to inhibit expansion of the compressed hay as it emerges. iee oeoeo•

11. A method of wrapping as defined in claim wherein the plastic film is a stretchable cling wrap film and r the method further comprises the step of: oro pre-stretching the film webs prior to wrapping about the hay whereby, in use, the film webs provide a S 25 containment force about the hay.

12. A method of wrapping as defined in claim 11, wherein the step of dispensing comprises simultaneously dispensing four film webs as the ring member rotates. SS 54

13. A method of wrapping as defined in claim 12, wherein the compressed hay is pre-cut into half bale sections. A hay bale wrapped in a web of plastic film in 17 17 accordance with the method of wrapping as defined in any one of claims 10 to 13. A hay bale wrapping apparatus substantially as herein described with reference to and as illustrated in the accompanying drawings.

16. A method of wrapping hay bales substantially as herein described with reference to and as illustrated in the accompanying drawings. DATED this 3rd day of November 1998 TKK ENGINEERING PTY LIMITED By its Patent Attorneys: GRIFFITH HACK Fellows Institute of Patent Attorneys of Australia e S o.e e o o ABSTRACT A hay bale wrapping apparatus (10) for wrapping compressed hay into bales is described. The hay is compressed in a press, and the compressed hay is ejected via a chute (12) of rectangular cross-section. As the compressed hay emerges from the end (14) of the chute (12) it passes through a first rotatable ring member (16) along a central axis (18) about which the ring member (16) rotates. Four rolls of film are rotatably mounted on the circumference of the ring member 10 (16) and a plurality of rollers are adapted to feed the film from the rolls to the hay bale. The feed rollers are arranged to pre-stretch the film prior to wrapping about the compressed hay so that the film webs provide a containment force about the compressed hay. The compressed hay is wrapped in the film webs immediately it emerges from the end °o (14) of the chute and therefore expansion of the compressed o°'o hay as it emerges is inhibited. A second rotatable ring member (30) also rotates about the central axis A Doa knife (36) is mounted on a support arm (38) which is pivotally connected to the second ring member At predetermined intervals, knife (36) cuts through the layers of film wrap and each hay bale separates from the bulk of the compressed hay under its own weight.