In prior art, e. g. a wrapping apparatus is known which is provided with wheels and designed to be hitched to the rear of a tractor. The apparatus has picking devices for picking up bales from the ground, a wrapping table on which the bale is rotated, a wrapping arm or a special wrapping frame especially for rectangular bales, rotating around the bale and provided with a plastic roll, a plas- tic holder and a plastic cutter. Large rectangular bales have been found to have e. g. the advantage that their an- gular shape allows them to be packed in a small space for transportation and storage. However, they have the draw- back that rectangular bales cannot be wrapped with plas- tic foil using small and cheap machines, but instead it is necessary to use large apparatus whose weight imposes a heavy load on the soil and which are too expensive for many farmers to buy, Therefore, rectangular bales have been wrapped using wrapping machines composed of smaller wrapping devices designed for e. g. for the wrapping of round bales with plastic. Such attempts result in low- quality and inefficient wrapping, Moreover, the amount of plastic needed in relation to the amount of fodder thus stored is about 30% larger than in the case of round bales.

The object of the present invention is to eliminate the drawbacks described above and to achieve a reliable and easy-to-use method and apparatus for the wrapping of bales, especially rectangular bales. The procedure of the invention is characterised by what is presented in the characterisation part of claim 1, and the apparatus of

the invention is characterised by what is presented in the characterisation part of claim 3. Other embodiments of the invention are characterised by what is presented in the other claims.

The solution of the invention has the advantage that the same wrapping device can be used to effectively wrap both round bales and rectangular bales while ensuring a very high fodder quality with a minimum plastic consumption. A further advantage is that other bale treatment operations in addition to the wrapping, e. g. loading, can be per- formed using the same apparatus. The wrapping of the bales can also be very flexibly carried out either in the place of storage, from a transport carriage or when the bales are being loaded onto a transport carriage on a field. A further advantage is efficiency-the apparatus has a capacity sufficient to allow it to be used in a high-efficiency baler chain. Additional advantages are simplicity and low price of the apparatus, so it is suited for use on smaller farms as well.

In the following, the invention will be described in de- tail by the aid of an example by referring to the at- tached drawings, wherein Fig. 1 presents a plastic-wrapping apparatus in an oblique rear view, Fig. 2 presents the same plastic-wrapping apparatus at the beginning of a wrapping operation, seen in top view, and Fig. 3 presents the same plastic-wrapping apparatus at another stage of a wrapping operation, seen in top view.

The apparatus of the invention will be described first to make it easier to understand the procedure. The bale treatment apparatus of the invention, hereinafter re-

ferred to as'apparatus', is driven e. g. by a tractor, to whose rear part it is hitched. The apparatus comprises a frame part consisting of at least a vertical support 2 and a supporting beam 1 disposed symmetrically above the frame part 2 and perpendicularly to it, i. e. in a sub- stantially horizontal position. At each end of the sup- porting beam there is a working arm 4 pivotally connected to the beam by its first end and acting as a loading and wrapping arm, which turns laterally about joint 28 and vertically about joint 27, In addition, the length of the working arm, i. e. the distance of its second end from its first end is adjustable, allowing the same apparatus to be used to handle bales of different sizes. The movements of the working arm are implemented using power means, of which the figures show a hydraulic cylinder 9 producing the lateral motion. Mounted at the other end of each working arm is a bale holding and rotating mechanism, which consists of a hydraulic motor acting as a rotation means 11, a rotating shaft 12 and a squeeze plate 10 at- tached to the shaft 12. The squeeze plates on the two working arms face toward each other so that, by turning the working arms 4 toward each other, a bale can be gripped between the squeeze plates 10 in order to move it, wrap it with plastic or load it onto a vehicle.

Placed in the vicinity of the squeeze plates is at least one mechanical detector serving to centralise the squeeze plates with respect to the bale. Moreover, the squeeze plate is connected to its rotating shaft via a ball joint to permit adaptation to a possible wobbling motion of the bale.

Connected in a horizontally turnable fashion by its first end to the lower part of the vertical support is a low supporting arm 3, whose other end carries a hydraulic mo- tor 14 and a rotating plate 15 attached to it by a shaft and designed to support the bale from below when the bale is being turned in a horizontal plane between different

stages of a wrapping operation. During wrapping, the low supporting arm is held in a lateral position to keep it out of the way when the bale is being rotated in a verti- cal plane, The turning movement of the low supporting arm is implemented using a hydraulic cylinder 16.

Placed above the supporting beam 1 and parallel to it are two guide bars 5 and 6, of which the upper guide bar 5 is attached by its ends to end plates 25 while the lower guide bar 6, which may disposed in a position somewhat closer to the bale, is attached by its ends to end plates 26. Slidably mounted on each guide bar is a roll carriage 29 with bearings supporting a wrapping foil roll 7,8 in a position parallel to the guide bars 5,6. The roll carriages are designed to be movable on the guide bars from end to end of the bar, the movement being controlled by a logic control system. The roll carriage movement is produced by a chain connected to each roll carriage and driven by a hydraulic motor. The range of movement of the roll carriages extends so far out that the horizontal distance between the outer ends of the plastic rolls at the beginning of a wrapping operation is larger than the corresponding width of the fodder bale 24 between the squeeze plates 10 of the working arms. This arrangement allows a portion of the plastic foil to be bent over the inner corners 22,23 of the bale at the beginning of the wrapping operation so that no part at the corners of the bale is left uncovered with plastic.

In addition, mounted in the immediate vicinity of each squeeze plate 10 is a holder and locking device 19a, 19b for the free end of the plastic foil, as well as a cut- ting device. After the bale has been wrapped with plastic foil, the free end of the plastic foil of each roll will remain secured in the holder, ready for the next wrapping operation. Moreover, as seen from above, the plastic foils are arranged in a crosswise manner so that the free

end of the plastic foil of the left-hand plastic roll 7 is held by the right-hand holder 19a while the free end of the plastic foil of the right-hand plastic roll 8 is held by the left-hand holder 19b, Bale treatment by the method of the invention is as fol- lows: The situation presented in Fig. 2 may be regarded as representing the start of a working cycle. The bale 24, held between the squeeze plates 10 of the working arms 4, has been taken up from a field, storage or other suitable place, To save plastic, the bale is gripped by its longer sides and the length of the working arms has been adjusted according to the bale length so that the squeeze plates grip the bale at about the centre of the bale side. Before starting the wrapping process, the plastic rolls 7,8 are driven by the logic control system into a crosswise position as illustrated by Fig. 2. In this situation, the distance between the outer ends of the plastic rolls is greater than the corresponding width dimension of the bale. This ensures that the plastic foil is bent over the inner corners 22,23 of the bale at the start, thus effectively protecting the bale, The free ends of the plastic foils are held in their holders 19a, 19b, The free end of the plastic foil of the left-hand plastic roll 7 is held by the right-hand holder 19a while the free end of the plastic foil of the right-hand plas- tic roll 8 is held by the left-hand holder 19b, Before the wrapping operation is started, the low supporting arm must be turned aside to make way for the bale.

The wrapping process is started by rotating the bale in a vertical plane by means of the rotation means 11. The crosswise plastic foils 17,18 at first go over the inner corners 22,23 of the bale and are partially bent onto the long sides of the bale, From this point, the process can be continued in two different ways, In a first alter- native, when the bale has been rotated through a first

half-revolution, the plastic rolls are quickly moved crosswise again, the bale is rotated again through half a revolution and the originally outer corners 20,21 are wrapped. After this, the bale is rotated continuously in a vertical plane while the plastic rolls are slowly driven toward each other, the bale being thus completely wrapped longitudinally until the plastic rolls have reached the midpoint of their range of movement.

In an alternative solution, after the inner corners have been wrapped, the plastic rolls are immediately driven slowly against each other and the rolls are moved, with- out rotating the bale, from their mid-position to the ex- tremities of their range of movement, and finally the originally outer corners 20,21 are wrapped.

At this point of the wrapping operation, regardless of which one of the alternative methods has been used so far, the second phase is started, The low supporting arm 3 is driven into position under the bale, the working arms 4 are released from the bale by turning them outward farther apart and the bale is rotated horizontally through 909 by means of the rotating mechanism 14, The plastic foils 17,18 now cross each other again and are bent over the corners 20 and 23. The bale is pressed by its ends between the squeeze plates 10 and lifted off the rotating plate 15, whereupon the low supporting arm 3 is turned aside. Next, the wrapping operation is finished by rotating the bale transversely between the squeeze plates 10 and moving the plastic rolls on their guide bars ei- ther from the middle towards the ends or from the ends towards the middle.

At the final stage of the wrapping operation, the plastic rolls are again moved to the ends of their guide bars, whereupon the free ends of the plastic foils fall into the holders 19a, 19b mounted near the other ends of the

working arms 4 and are locked in the holders. After this, the portion of the plastic foil between the bale and the holder is cut off, leaving the free end of each plastic foil locked in the holder, whereupon the bale can be dropped down from between the squeeze plates.

It is obvious to the person skilled in the art that the invention is not restricted to the example described above but that it may be varied within the scope of the claims presented below. Thus, for example, according to a preferred embodiment, the apparatus may be so constructed that the bale itself is not rotated but instead the plas- tic rolls 7,8 together with the guide bars 5,6 and roll carriages 29 are driven in an orbit around the bale. In this case the squeeze plates 10 are only used to keep the bale raised during the wrapping operation. Correspond- ingly, connected to each working arm are a rotating mechanism and an L-shaped rotating arm with a roll car- riage 29 and a plastic roll mounted in its portion paral- lel to the axis of rotation, The portions parallel to the axis of rotation of the rotating arms are placed oppo- sitely to each other and so dimensioned and synchronised with respect to each other that the roll will not touch each other, The rotating mechanisms may be so constructed that the path of the plastic rolls around the bale is not necessarily a perfect circle but rather an adapted'quad- rangular'orbit. In this case, the apparatus is provided with a separate chain-operated track attached to the working arms and placed laterally relative to the bale, said track being of a rectangular shape as seen from the side, approximately conforming to the dimensions of the bale. The roll carriage travels around the bale along this chain track, remaining at substantially the same distance from the bale all the time.

The actual wrapping function is in principle the same as that described above in conjunction with the apparatus according to a second embodiment.

This solution has the advantage that the apparatus can be used to wrap bales of different shapes, including shapes other than rectangular.

Instead of using logic control, the control of the wrap- ping operation can be implemented using e. g. a microproc- essor or equivalent,