A BALE WRAPPING MACHINE

Abstract: An apparatus (1, 20) for wrapping bales (2, 28) which has a turntable (24) for supporting a bale, conveying means (31, 32, 36) to turn the bale about a substantially horizontal axis, and a dispenser (26) for continuously supplying a strip of wrapping material (74) to the bale, to wrap the wrapping material about the bale. The turntable and the dispenser are rotatable in opposing directions, allowing for more rapid wrapping of the bale.

Description: A BALE WRAPPING MACHINE Field of the Invention The present invention relates to a bale wrapping machine, in particular a bale wrapping machine for bales of fodder such as silage, hay, straw etc., ("fodder") with a plastics film. Background of the Invention Bale wrapping machines are known for wrapping rectangular and cylindrically shaped bales. Machines for wrapping cylindrically shaped bales with a plastics film are described in British application nos. 2191984-A and 2228246-A and European application no. 0208034A (GB 2159489B). Wrapping machines for rectangular bales are also known. Such machines are described in German Gebrauchmuster No. G9004354.5 (Gebruder Welger GmbH & Co. KG). It is known from the prior art, for example in EP-B-0110110, DE-A-3642513, and GB-A-2193683, for the bale to be mounted on rollers which rotate the bale only about the horizontal axis. In this arrangement there is provided a rotary support arm for the film dispenser which rotates the film dispenser, about a vertical axis, around the bale, while the bale is being turned about a horizontal axis. In other wrapping machines the bale is rotated about its longitudinal axis while simultaneously being rotated about a transverse axis. In these latter type of machines the film dispenser has a fixed position on the wrapping machine. High speed rotation of bales for wrapping is limited by two factors - one of which is the tendency of the wrapping film to break if placed under high tensions. The second factor is the tendency of the bale (and or the entire wrapping machine) to become more unstable as speed of rotation is increased. Bales of fodder tend to be heavy, particularly those of silage. Furthermore the bales are not formed with a evenly distributed weight. At higher speeds the unevenly distributed weight results in an offset of the centre of gravity of the bale resulting in a rocking motion of the bale and in turn of the turntable. The higher the speed of revolution, the greater the rocking motion, the more unstable the machine becomes. Object of the Invention It is an object of the present invention to provide a bale wrapping machine which can wrap bales more rapidly than conventional machines, without comprising the safe- working of the machine. Summary of the Invention The present invention provides a bale wrapping machine comprising : a rotatable support for supporting a bale, means to turn the bale about a substantially horizontal axis, and a dispenser for continuously supplying a strip of wrapping material to the bale, to wrap the wrapping material about the bale characterised in that the support and the dispenser are rotatable in opposing directions. This mechanism allows the bale to be wrapped at a substantially increased speed, without the necessity to increase the speed of the rotatable support or the film dispenser beyond normal speeds. With opposing rotation, 360° of wrapping can be effected by a 180° revolution of the bale. Suitably the means to turn the bale comprises conveying means. In one arrangement the means to turn the bale rotates with the rotatable support. Preferably the support and the bale rotate in opposing directions about a substantially vertical axis. Suitably the apparatus further comprises a second dispenser for continuously supplying a second strip of wrapping material to the bale. This embodiment allows for even more speedy wrapping of the bale. In one arrangement the dispensers are spaced about 180° apart about the rotatable support. In a preferred construction the dispenser, or both dispensers, comprise at least one powered dispensing roller for the wrapping material. Powering the dispensing roller(s) allows the film to be dispensed at higher speeds with less instances of breakage of the film. The bale wrapping machine of the present invention may be used with either rectangular (square) or cylindrical bales. A machine according to the present invention is quite easily made by modification of existing wrapping machines. Brief Description of the Drawings Figure 1 is a schematic representation of a bale wrapping machine of the present invention; and Figure 2 shows an end view of a bale wrapping machine of Figure 1 in more detail; and Figure 3 is also an end view of the machine of Figure 2 with the bale no longer on the turntable, the turntable having being rotated 90 ; and Figure 4 is a top plan view of the rotation systems for the turntable and the dispensers with a bale in place on the turntable. Detailed Description of the Drawings The embodiment described in the drawings is described with reference to a wrapping machine 1 for wrapping a cylindrical bale. The technology can easily be applied to a wrapping machine for rectangular or square bales. With reference to Figure 1 a schematic view of a wrapping machine 1 is shown. A bale 2 is placed on a cradle formed by two rotating rollers 3,4 (which form conveying means and which additionally may have a conveyor belt extending between them) and a supporting turntable (not shown) which forms a rotatable support for the bale. The rollers 3,4 rotate the bale (travelling with the turntable) about its longitudinal (substantially horizontal) axis. The rollers are rotated in the direction of the arrows labelled 5 and this causes rotation of the cylindrical bale 2 in the direction of the arrow 6. While a single conveyor belt is preferred, the machine could have a series of belts known as "strip belts" forming the conveying means to turn the bale. In some machines the conveying means is formed by rollers (with no belt between them) which directly turn the bale. These rollers would usually be provided with friction surfaces for engaging the bale. The turntable is powered for rotation in the direction of the arrow 7. Dispenser 8 for a plastics wrapping film is mounted on a rotating arm 9. The rotating arm 9 is mounted on the bale wrapping machine in a conventional manner e.g. on a mast and is powered to rotate in a direction opposite to that of the turntable. The rotating arm 9 is powered to rotate in a direction according to the arrow 10 which as can be seen from Figure 1 is opposite in direction to the direction of rotation of the cradle (arrow 7). The opposing rotational (contra-rotating) movement of the film dispenser 8 and the cradle effectively increases the relative wrapping speed of the bale 2. To compensate for the increased wrapping speed about the bale 2 the speed of rotation of the rollers 3,4 can be increased so that the wraps of plastics film are placed about the bale in a suitable manner. This is within the skill of a person familiar with this technology. The particular rotational speeds to be adopted for the turntable, the dispenser and the rollers 3, 4 is determined by the required speed of wrapping and is easily determined by one skilled in the art. A second rotating dispenser could be fitted to the machine of the invention, to further increase wrapping speed if desired. The two dispensers would normally rotate in the same direction, and would be placed on the machine a distance of about 180° apart about the wrapping machine so as to allow a maximum distance between them so that the second dispenser can apply a wrapping which partially overlaps with a wrap which has been applied by the first dispenser. While the preferred angle is 180 apart the dispensers could be placed closer together about the turntable. If the dispenser and the turntable are geared to rotate at the same speed in opposite directions, 360° of relative rotation can be achieved for every 180° rotation of the bale thus doubling the wrapping speed of the machine as compared to a conventional wrapping machine which has either a rotating dispenser or a rotating turntable. In order to alleviate the problem of breakage of plastic film at the higher speeds of rotation achieved by a machine of the present invention a "power stretcher" of the type described in International application no. WO 94/20367 or International Application no. WO 97/00202 may be used. For conventional wrapping films applied at speeds lower than about 36 - 40 wraps per minute (one wrap is equivalent to one half revolution of the bale in the present machine) stretching of the film prior to application to the bale or other power assisted dispensing is not necessary. A wrap is one complete web of film encircling the bale. The speed range given applies to each dispenser individually. A power stretcher has a pair or stretch rollers for stretching the film. The stretch rollers are powered by a hydraulic motor which is connected in series to a hydraulic motor for powering the film dispenser. Power stretchers help the application of the wrapping film about the bale by helping to maintain a constant tension in the web of film. This helps to apply the film evenly about the bale. The power stretcher feeds the web of film to the bale, rather than relying on the tension from the bale to the dispenser to pull the film from the dispenser. This alleviates the problem of breaking of the film due to excessive tension. A more detailed description is now given with respect to Figures 2 to 4. The wrapping machine shown in Figures 2 to 4 describes a wrapping machine such as is shown in Figure 1 in more detail. The machine includes some features described as optional for the machine of Figure 1. The wrapping machine 20 has a chassis 21 supported on an axle 22. Wheels 23 allow the machine 20 to be towed behind a tractor. Otherwise the machine 20 could be mounted on a slide which allows the machine to be trailed. On the chassis 21 is mounted a turntable 24. The turntable 24 is rotatable in the direction of the arrow 25. Also mounted on the chassis 21 are two dispensers 26 rotatable in the direction of the arrow 27. It will be appreciated that the respective directions of rotation of the turntable 24 and the dispensers 26, could be reversed so that they counter rotate in a reverse direction to that shown. Only one of the dispensers 26 is visible in the view of Figure 2 the second being obscured by a bale 28. Both are visible in the view of Figures 3 and 4. A cylindrical bale 28 is nested in the turntable 24 and is rotated in two directions at once by revolving of the turntable and by a belt mounted on rollers as described in more detail below. The bale 28 is rotated about a transverse axis in the same direction as the turntable 24 as indicated by the arrow 29 (above the bale). Simultaneously with the rotation about the transverse axis the bale 28 is also rotated about a longitudinal axis as shown by arrow 30. The turntable 24 has a pair of spaced belt rollers 31,32 which are mounted horizontally on the turntable by bearings 33 on pairs of arms 34,35 which pivot with the turntable. The rollers 31,32 are mounted for rotation about horizontal axes on the arms 34,35. An endless belt 36 is mounted about the rollers 31,32. The conveyor belt 36 is an endless belt made from a suitable rubberised fabric and may have cleats, ribs or the like on the surface thereof to improve its frictional properties. The width of the belt 36 is substantially the full width of the belt rollers 31,32. Details for the mounting and operation of the rollers 31 and 32 are well known to those skilled in the art. The rollers 31,32 and arms 34,35 (together with the belt 36) define a well or cradle 37. The cradle 37 is adapted to receive the large cylindrical bale 28 of silage or other fodder for wrapping. The bale can be lifted into the cradle by means of a front loader or by using a hydraulically-operated lifting device forming part of the machine such as already known in the field of bale wrapping machines. When in the cradle 37, the bale is carried on and is rotated by the conveyor belt 36 as described above. The turntable 24 is mounted for rotation on the chassis 21 by a cylindrical axle or spindle 38 mounted on a slewing ring 39 on the chassis allowing powered rotation of the turntable 24 in a horizontal plane as described above. The rotation of the turntable 24 is powered as in conventional machines for example driven by gearing powered by the power take-off (pto.) shaft of a tractor, or hydraulically by a pressurised hydraulic supply from a tractor or from an alternative source of hydraulic pressure. One conventional method is to supply hydraulic fluid to a hydraulic motor which is geared to drive the slewing ring 39 by means of cogs on the slewing ring. The dispenser 26 has a vertical dispensing mast 40. Two aligned main brackets, an upper bracket 41, and a lower bracket 42 are each mounted on the mast 40 and project substantially parallel to each other at right angles to the mast 40. Between the brackets 41,42 are located four substantially vertically orientated rollers numbered 43,44,45 and 46. On the roller 43 there is located a roll 49 of plastics film to be dispensed and wrapped around the bale 28. The rollers 45,46 are mounted as a pair, fixed relative to each other by a pair of brackets - an upper bracket 47 and a lower bracket 48. The brackets 47, 48 hold the pair of rollers 45,46 between the main upper and lower brackets 41,42. The assembly of the brackets 47,48 and the rollers 45,46 is rotatable with respect to the main brackets 41,42. In a normal operating mode the film is fed from the roll 49, behind (taking the perpective of Figure 2) the roller 44, across the face of roller 44, behind roller 45 and across the face of roller 46. The roller 45 and 46 being independently pivotable can rotate so that roller 45 abuts the roller 44 to pinch (and pull) the film. The dispenser mast 40 is mounted on an arm 50 which is rotatably mounted on the chassis 21 in the manner described above for the turntable 24 by a further slewing ring 51. The pair of rollers 45,46 act as distributing or tensioning rollers and maintaining film passed between the rollers for wrapping about the bale 28 in a tensioned state. The arrangement of these rollers could be as described in WO 94/20367 or WO 97/00202. The freedom of movement of the assembly of the brackets 47,48 and the rollers 45,46 allows for the tension in the plastics film to be maintained as the dispenser 26 follows its path around the bale. Both dispensers 26 may be powered for rotational movement by any suitable arrangement for example as described above for the turntable 24. A second dispenser 26 is disposed on the opposite side of the platform 50 spaced 180 from the first dispenser. The construction of the second dispenser is identical to that of the dispenser already described above. Figure 3 shows the wrapping machine of Figure 2. It will be noted that the machine does not have a bale mounted thereon to avoid obscuring the view of the machine. Furthermore the turntable 24 has been rotated through 90 so that the rollers 31,32 are now disposed with their longitudinal axis transversely disposed across the machine. Side rollers 56 which maintain the position of the bale 28 in the cradle 37 of Figure 2 are more clearly visible in the view of Figure 3. The rollers 56 are held in place on the turntable 24 by brackets 71 and rotate with the turntable 24. The arms 50 on which the dispensers 26 are mounted are shown from a side perspective in Figure 3. The brackets 50 are z-shaped between the mounting end 72 mounted on the slewing ring 51 and a dispenser mast, holding end 73. The dispensers 26 are arranged so that the rollers 43-46 face in opposite directions (from the view of Figure 3) to allow them to work in tandem wrapping the bale. One dispenser follows the other about the bale, dispensing film. The combination of the provision of the dual dispensers together with the opposing rotation of the turntable and the dispensers allows for rapid wrapping of the bale without the necessity to provide a more rapidly rotating turntable. A top schematic view shown in Figure 4 with the bale 28 in place. The belt rollers 31,32 can be seen supporting the bale 28. The end rollers 56 are also seen acting to hold the bale in place in the cradle 37. Each of the dispensers 26 are shown, and as described above, they face in opposing directions about the bale 28. The respective slewing rings 39 and 51 for the turntable 24 and the dispenser 26 are also shown in dashed outline. Each film dispenser 26 may include a cut and start device for severing the film at the end of wrapping and for initiating the wrapping of the next bale to be wrapped. A suitable cut and start device is disclosed in US patent no 5,740,662 (in particular Figure 15). To commence wrapping a free end of each of the plastics film 74 is attached to the bale 28 (by a cut and start device). The film dispensers 26 are then caused to rotate around the bale 28 to wrap the bale in plastics film in a well known manner. The bale when wrapped can be lifted from the turntable or can be dislodged from the turntable by making the turntable tippable on action of tipping rams. The words "comprises/comprising" and the words "having/including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

Claims: CLAIMS 1. An apparatus for wrapping bales comprising : a rotatable support for supporting a bale, means to turn the bale about a substantially horizontal axis, and a dispenser for continuously supplying a strip of wrapping material to the bale, to wrap the wrapping material about the bale characterised in that the support and the dispenser are rotatable in opposing directions. 2. An apparatus according to claim 1 wherein the means to turn the bale comprises conveying means. 3. An apparatus according to any one of the preceding claim wherein the means to turn the bale rotates with the rotatable support. 4. An apparatus according to any preceding claim wherein the support and the dispenser rotate in opposing directions about a substantially vertical axis. 5. An apparatus according to claim any preceding claim further comprising a second dispenser for continuously supplying a second strip of wrapping material to the bale. 6. An apparatus according to claim 5 wherein the dispensers are spaced about 180° apart about the rotatable support. 7. An apparatus according to any preceding claim wherein the dispenser, or both dispensers, comprise at least one powered dispensing roller for the wrapping material.

Inventors: BELTON CHRISTOPHER, BELTON, CHRISTOPHER
Applicants: ARBOC LIMITED, BELTON CHRISTOPHER, BELTON, CHRISTOPHER
Application year: 1999
Main classification: B65B11
IPC codes: A01F15, B65B11