WO1999065773A1

WO1999065773A1 - Method and apparatus for forming a bundle

Info

Publication number: WO1999065773A1
Application number: PCT/SE1999/000736
Authority: WO
Inventors: Mats Wilstrand
Original assignee: Wilstrand Innovation I Hedemora Ab
Priority date: 1998-06-15
Filing date: 1999-05-04
Publication date: 1999-12-23
Also published as: AU4402699A; SE9802127D0; EP1087889A1; SE9802127L; SE514201C2

Abstract

The invention relates to a method of bundling woody plants, said plants being successively fed to and gathered in a bundling unit (8) where the plants and the continuous bundle being formed are subjected to a rotary movement and a simultaneous substantially linear movement in the longitudinal direction of the continuous bundle being formed. According to the invention the plants are fed onto a supporting plane (7) on which they are engaged and conveyed in a direction generally transversal to the longitudinal extension of the plants and sideways into the bundling unit.

Description

METHOD AND APPARATUS FOR FORMING A BUNDLE Field of the invention

The present invention relates- generally to the field of biomass energy and more specifically relates to a method and an apparatus for forming a bundle of woody plants for use in this field, and of the kinds specified in the preambles of the enclosed claims 1 and 7 respectively. Description of the prior art

In line with the present increasing environmental concerns much work has been performed with the aim of developing techniques and equipment for producing renewable energy, mainly for use as fuel for heating purposes and for generating electric energy. Thus, such techniques and equipment have been developed for planting and harvesting energy forest and other kinds of brushwood, icluding sugar cane, corn stalks, etc. At the present stage the harvested plants are predominantly cut into wood chips immediately upon harvesting, i.e. in most cases in combined machines harvesting and cutting the plants in the field.

Such a processing of the plants into wood chips at this early stage causes several problems that are well known within this field, such as the need for complex and expensive machines and the danger of self-combustion in stacked wood chips.

In view of the above there is a demand for alternative solutions that focus on collecting the harvested plants in bundles, thereby requiring less complex machines, and storing the plants in said bundles, thereby eliminating the danger of self-combustion. The basic idea of collecting the plants and forming bundles thereof for transportation and storage as well as a general idea of a machine for collecting the plants and for forming a continous bundle which is then cut up into separate bundles, are disclosed in U.S. Patent No. 4,399,745, which forms the prior art from which the present invention starts.

However, said prior art method and machine suffer from severe drawbacks which have contributed to the fact that this technique has not been further developed and has not yet reached the market. One basic disadvantage is that in order to operate satisfactorily the machine will have to be extremely long and thereby difficult to manoeuvre in the field as well as during transport thereof to and from the field. More specifically the extreme length of the machine is required by the disclosed technique of inserting the plants, which may be up to 6 metres long, lengthwise into a bundle former by which a continuous bundle is formed with the succesive insertion of new harvested plants.

Another unsatisfactory design solution of the prior art machine is a bundle former consisting of a plurality of separate circular disks intended to provide a rotary movement to the plants as the bundle is formed.

Summary of the invention The object of the invention is, therefore, to provide a method and an apparatus of the above indicated kind which permit the formation of bundles of biomass energy plants in an efficient manner and in a comparatively restricted space, and yet to a very competitive cost.

According to the invention these objects are obtained by means of a method and an apparatus having the features of the characterizing portion of the enclosed claims 1 and 7 respectively.

Preferred further developments and embodiments of the invention are specified in the dependent subclaims.

Brief description of the drawings

Further objects, features and advantages of the present invention are described below in connection with exemplifying embodiments thereof, which are illustrated in the enclosed drawings, on which:

Fig. 1 is a perspective view of a first embodiment of the apparatus according to the invention, for bundling plants,

Fig. 2 is a plan view from above of the embodiment according to Fig. 1,

Fig. 3 is a side view of the embodiment according to Fig. 1, Fig. 4 is a front view of the embodiment according to Fig. 1,

Fig. 5 shows a section of an embodiment of a chain for the infeed device of the apparatus of Figs. 1-4,

Fig. 6 shows a section of a conveyor chain in the platform of the apparatus according to Figs. 1-4,

Fig. 7 is a perspective view of a second embodiment of the apparatus according to the invention, for bundling plants,

Fig. 8 is a plan view from above of the apparatus according to Fig. 7,

Fig. 9 is a front view of the apparatus according to Fig. 1, and

Fig.10 is a schematical illustration of the movable link system of the bundling tunnel in the embodiment illustrated in Figs. 7-9.

Detailed description of the preferred embodiment

The invention will be further described below with reference first of all to Figs. 1-4 which illustrate an embodiment of the apparatus 1 according to the present invention that is intended for harvesting and bundling woody plants of any kind, such as energy forest and other biomass energy plants, sugar cane and corn stalks.

In the illustrated embodiment the apparatus 1 is designed to be towed as indicated in the drawing figures by means of the drawbar 2 and the coupling 3 to be connected to the power take-off of for instance an ordinary agricultural tractor. However, although such a towed design is presently preferred, mainly for reasons of cost, the invention is likewise applicable to a self-propelled machine.

The bundling apparatus or bundler 1, in the illustrated embodiment, generally consists of the following main units; a cutting unit 4 for successively cutting off the growing plants as the apparatus 1 is advanced, an infeed unit 5 for receiving the growing plants and holding/stabilizing them during the cutting-off and for feeding the cut-off plants to the actual bundling assembly of the apparatus 1, a platform unit 7 onto which the cut-off plants are fed by the infeed unit 5 and which in turn takes over the responsibility for the further feed of the cut-off plants, a bundling unit 8 for forming a continuous bundle of the cut-off plants, and a bundle cutting and strapping unit 9 for providing separate strapped bundles of predetermined length.

For the cutting unit 4 the illustrated embodiment of the bundling apparatus 1 employs a design that has proven itself to be very efficient and reliable in harvesting machines for energy forest and which does therefore not constitute any part of the present invention. Said cutting unit 4, which is only schematically illustrated in the drawings, consists of a right-angled frame 41 which is opened forwardly, i.e. in the towing direction C of the apparatus 1. At the free ends of the forwardly directed legs of the frame 41 ground engaging nose pieces 42 are provided. Said nose pieces 42 are provided with skids 42a intended to slide on the ground so as to maintain the cutting unit 4 on the correct height for cutting the plants. Around pulleys (not illustrated) in the frame 41 an endless saw chain 43 is driven such that an unsupported section of the chain 43 spans the distance between the free ends of the frame 41. In a manner not illustrated in the drawings, sections of the endless chain 43 run within the frame 41, around further, not illustrated pulleys, of which at least one is driven by a likewise not specifically illustrated motor. Finally a section of the saw chain 43 spans the distance between the legs of the frame 41 at a small distance from the base of said legs.

The infeed unit 5 is likewise designed and functions according to conventional basic principles and consists of two separate infeed conveyors 51, 52 which between them form a relatively narrow space 56 (Fig. 2)through which the plants are fed from the receiving end 53 to the output end 54 of the infeed unit 5. At the receiving end 53 each such infeed conveyor 51, 52 is provided with a guide member 55 for securely guiding the plants successively into the space between the infeed conveyors 51, 52 which are separately, firmly secured to the basic frame or chassis 100 of the apparatus 1, said chassis rotatably supporting running wheels 101 of the apparatus. The guide members 55 are each provided with a single conveyor chain 55a passed around pulleys 55b at the respective ends of each guide member 55, as illustrated in Fig. 1, for guiding and feeding the gathered plants into said plant receiving space 56 between the infeed conveyors 51, 52. Each such infeed conveyor 51, 52 consists of a base structure 57 in each of which two separate, endless conveyor chains 58, 59 (only partially illustrated in the drawings) are arranged, passed around respective pulleys 65, 66 and running in chain guides 67, 68 between the respective pulleys 65, 66.

The links of the conveyor chains 58, 59 are provided with drivers 63 for engaging the plants, as will be described more closely below, with reference to Fig. 5. The arrangement of the conveyor chains 58, 59 in each infeed conveyor 51, 52 is such that said chains 58, 59 have substantially the same extent and are positioned one above the other, spaced apart by a distance decreasing from the infeed end 53 towards the output end 54 of the infeed unit 5. In order to exemplify this varying distance it may be specified that in one embodiment successful tests have been performed where the distance between the upper and lower chains 58, 59 is 20-25 cm at the infeed end 53 whereas said distance gradually decreases to 5-10 cm at the output end 54. This arrangement in combination with the feature that the upper conveyor chain 58 is driven at a higher speed than the lower chain 59, in said tested embodiment at approximately 25% higher speed, produces the result that the plants that are received in a substantially vertical position at the infeed or receiving end 53, are gradually brought to a substantially horizontal position as they are conveyed through the receiving space 56.

In the above described manner the plants will be discharged at the output end 54 of the infeed unit 5 onto the platform unit 7 in a substantially horizontal position, thereby securing that the plants are positioned in order on the platform unit 7, in the proper position.

In Fig. 5 a short section of the infeed conveyor chain 58 or 59 is illustrated, which is basically designed as an ordinary chain consisting of interconnected links, where the inner links 60 have a conventional design whereas the outer links 61 are formed of an outer guide portion 62 slidingly engaging the respective guide members 67, 68 of the conveyors 51, 52 and a driver member 63 having a generally outwardly tapering shape, the purpose of which is to engage the plants. It will be appreciated that in the assembled condition said conveyor chains 58, 59 are arranged such that in the receiving space 56 each pair of upper and lower conveyor chains 58, 59 cooperate to hold and advance the received plants. In the design of the chains 58, 59 described above this is accomplished by the fact that in said section of the chains the driver members 63 of each pair of upper or lower chains 58, 59 are directed towards each other for forming plant receiving pockets 64 between adjacent links of the opposite chains. For achieving the best result the driver members are preferably manufactured from a suitable rubber material. The above described chain design in combination with the gradually decreasing distance between the upper and lower conveyor chains of each infeed conveyor as well as the difference in speed between the upper and lower chains provides for a very favourable and secure infeed of the plants and a discharge of the plants in a near horizontal position on the platform unit 7.

Said platform unit 7 basically consists of a lower frame 70 firmly connected to the above described base frame 100 of the apparatus 1. On said lower frame 70 is supported an upper plant supporting platform 71 which may preferably be formed by interconnected square steel bars and plate sections covering the spaces between the square bars, so as to form a supporting plane for the plants discharged from the infeed unit 5. Said plant supporting platform 71 may be substantially horizontal, but in the preferred embodiment it is inclined slightly in relation to the horizontal plane, and more specifically so as to become lower in the later described feeding direction B of the formed bundle, so as to support such a feeding movement of the bundle.

On said platform 71 are provided a number of, in the illustrated embodiment four, platform conveyors 72 consisting of second, endless conveyor chains 73, see especially fig. 6, extended in a direction D generally transversal to the longitudinal direction of the plants discharged onto the platform unit 7 and to the towing direction C. Each of the platform conveyor chains 73 is guided in platform guide members 74a, 74b, 74c of which a first guide member 74a is extended in the support plane of the platform 71 and continues in a second guide member 74b extended around the inner periphery of the partially open bundling tunnel 80 of the bundling unit 8, which will be described more closely below. The second guide member 74b preferably extends in a helical path along the full inner periphery of the bundling tunnel 80, for reasons discussed below, but may very well, for certain applications, be extended only over a part of the inner periphery of said tunnel 80. Close to the end of the second guide member 74b the chain 73 runs over a pulley 75 a and into a third guide member 74c extended along the outer periphery of the bundling tunnel 80. Said last mentioned pulleys 75a of all platform conveyors 72 are preferably drive pulleys of the conveyors and are therefore supported on a common shaft 75b driven by a motor not illustrated in the drawings.

The third guide members 74c have a specific design with relatively high side plates (compare especially with fig. 1) so as to serve a triple function, and specifically their first purpose is to guide the conveyor chain 73 as it returns on the outside of the tunnel 80; their second purpose is to cover the chain 73 and its driver members, described further below, for safety reasons; and their third purpose is to strengthen the bundling tunnel 80. From said third guide member 74c the platform conveyor chain 73 passes over a second pulley (not illustrated in the drawing figures) and returns below the support plane of the platform 71 extending across the platform 71 to a third pulley 75c around which the chain 73 runs so as to reenter the first platform guide member 74a.

As is illustrated in fig. 6 the platform conveyor chains 73 are preferably also chains of a traditional design having interconnected links 73a, 73b, where the outer link on one side is formed by a platform driver member 73b, preferably made of steel. Said platform driver members 73b of the platform conveyor chains 73 are directed such that as the chains 73 run through the first and second guide members 74a and 74b the driver members 73b extend up through a longitudinal slot 74d in the guide members 74a, 74b and engage the plants discharged onto the platform 71, for moving them sideways into the partially open bundling tunnel 80 and also to rotate them whithin the bundling tunnel 80.

The above described features of the apparatus according to the invention, providing for the movement of the plants in a direction generally transversal to the longitudinal extension of the plants and sideways into the bundling unit is a basic feature of the invention resulting in a very compact bundling apparatus, as compared to the prior art where the plants are moved longitudinally into the bundling unit.

In the illustrated embodiment, see especially Fig. 3, the bundling tunnel 80 is in the shape of a steel cylinder open at both ends and with a portion of its peripheral wall removed for forming an infeed opening 81 extending the full length of the tunnel 80 and corresponding to approximately one quarter of its circumference. The bundling tunnel 80 is moreover preferably positioned such that its centre axis forms an angle larger than 90°, preferably in the area of 110-130° with the general feeding direction of the plants on the platform 71, i.e. with the longitudinal direction of the platform conveyor chains 73 in the first guide members 74a.

By this angular arrangement of the bundling tunnel 80 the very favourable effect is achieved that a combined rotation and forward feed of the plants in the bundling unit (in accordance with the general principles of the above mentioned prior U.S. Patent 4,399,745), during formation of the bundle, is realized in a very simple, uncomplicated and thereby inexpensive manner. More specifically, by allowing the platform conveyor chains 73 to be extended in one vertical plane in the first guide member 74a on the platform 71 and by positioning the bundling tunnel 80 in the above described angular position in relation thereto, the conveyor chains 73 will automatically enter the bundling tunnel 80 at an angle corresponding to the helix angle of a helical shape of the second guide member 74b at the inner periphery of the bundling tunnel 80 and of the third guide member 74c at the outer periphery of the bundling tunnel 80, to thereby provide the combined rotational and forward feeding action for the plants during formation of the bundle. In order to simplify the drive arrangement for the drive pulleys 75a through one common shaft 75b these pulleys are, however, provided perpendicular to the centre axis of the tunnel 80, and this change of direction of the chains 73 is in the order of a few centimeters and is admitted by the play in the chains and by the fact that the corresponding end portions of the second and third guide members 74b and 74c respectively, gradually divert from the helical shape to the perpendicular shape.

Although not illustrated in the drawings, the bundling tunnel 80 may advantageously be provided with a short, slightly inwardly tapering section at its bundle discharge end, i.e. closest to the cutting and strapping unit 9. The purpose of this tapering section is to compact the formed bundle without creating to large a resistance to the feeding movement of the formed bundle, and therefore the cross section of the tunnel 80 should be reduced to approximately correspond to the inner surface of the guide members 74b or slightly smaller.

From the described bundling tunnel 80 the formed continous bundle is fed to a cutting and strapping unit 9 which is only schematically illustrated in drawing figures 1-4 and which need not be described in any specific detail since it may preferably employ conventional apparatuses, such as a cutting apparatus 91 and a strapping apparatus 92. Thus, the cutting apparatus 91 may for instance be a conventional guillotine-type cutting apparatus whereas the strapping apparatus 92 may be of any conventional kind suitable for providing straps at regular distances from each other around the bundle being fed therethrough. Finally the formed, cut-off and strapped bundle is discharged from the apparatus 1, and due to the angular position of the bundling tunnel 80 the formed bundles are discharged safely at one side of the apparatus.

With the bundling apparatus 1 as described above, the basic principle of the present invention is achieved, namely that a very compact and simple design is realized, and more specifically this is achieved by means of the unique principle of discharging the harvested plants onto a platform 70 on which the plants are subsequently conveyed sideways into a partially open bundling tunnel 80. With this unique bundling forming technique it will primarily not be necessary to adapt the apparatus to the very varying length of for instance energy forest plants, which may be up to approximately 6 meters long.

Specifically, in the embodiment illustrated in Figs. 1-4, the harvested plants are positioned on the platform 71 by the infeed unit 5, with their root ends at a generally fixed position rear- wardly with respect to the general infeed direction A (see Fig. 2). In view of the fact that the plants are then conveyed sideways in the manner described above, on the platform, said position of the root ends is maintained such that the formation of the bundle starts with the root ends of the plants at a fixed position, irrespectively of the actual length of the plants, said bundle forming direction B being reversed with respect to the infeed direction A in the illustrated embodiment. Theoretically, it would naturally be possible, at a significantly higher cost, to turn around the plants such that their root ends would be positioned forwardly with respect to the general infeed direction A and to form the bundle in a direction corresponding to said general infeed direction, i.e. revsersed with respect to the bundle forming direction B as indicated in Fig. 2. In such a theoretically possible embodiment the cutting and strapping unit 9 would naturally be positioned to the right in drawing figure 2.

A second embodiment of the present invention will now be described with specific reference to Figs. 7-10, said embodiment being identical to the first embodiment with respect to the drawbar 2, the coupling 3, the plant cutting unit 4, the infeed unit 5, the cutting and strapping unit 9 and the base frame 100 with wheels 101, and therefore the same reference designations are used for said parts and a specific description thereof will be omitted. Also, the different chains, i.e. the saw chain, the infeed conveyor chains and the platform conveyor chains and their respective pulleys have been eliminated from figs. 7-9 for reasons of clarity.

In this second embodiment the main difference as compared to the first, above described embodiment is that the apparatus 1' of the second embodiment employs an adjustable or variable bundling tunnel 80' in the bundling unit 8'.

Said variable bundling tunnel 80' is formed by a series of link systems 81 ' (Fig. 10), preferably one link system 81' for each of the later described tunnel chain sets 82'. Each link system 81 ' consists of a number of, in the illustrated embodiment four, pivotally interconnected links 81 'a, 81 'b, 81 'c and 81 'd, the first link 81 'a being pivotally supported by the platform 71 ', specifically by being freely pivotally journalled on a shaft 83 'a which is rotatably journalled in the platform 71' and which carries one pulley 84 'a for each link system 81 '. Moreover freely rotatable shafts 83'b, 83'c, 83'd and 83'e are supported by all of the link systems 81 ' at the pivotal connections between the links 81 'a, 81'b, 81'c and 81 'd and at the free end of the last link 8 I'd, said shafts each carrying two pulleys 84'b, 84'c, 84'd except for said last shaft 83'e which carries one single pulley 84'e. It will now be understood that in each conveyor chain set 82' one conveyor chain 82'a, 82'b, 82'c and 82'd is extended around each corresponding pair of pulleys for forming a conveyor structure corresponding to that of the first embodiment although allowing for the adjustability of the width of the bundling tunnel 80'.

In this embodiment of he bundling tunnel 80' it is not possible to make the same efficient use of the inclination of the bundling tunnel in order to obtain the helical conveyor form, and therefore the bundling tunnel is preferably extended at a right angle to the direction D of extension of the platform conveyor chains 73'. Accordingly, in this embodiment the bundle forming direction B' is also substantially perpendicular to the direction D and parallell to the towing direction C. Therefore, in order to obtain the rotational and forward conveying movement of the bundle being formed, said pulleys are tilted relative to a plane perpendicular to their respective shaft, in a manner not specifically illustrated in the drawings.

As indicated in Fig. 10 the conveyor chain sets 82' are preferably driven by the respective platform conveyor chain 73' by providing a further rotatably journalled shaft 85' in the plat- form 71' said shaft carrying pulleys 85'a for the platform conveyor chains 73' as well as for a further drive transmitting chain 86' which is also extended over a further, not illustrated pulley on the first link system shaft 83 'a.

The drive means for manoeuvring the link systems in order to vary the width of the bundling tunnel 80' are not illustrated specifically in the drawings but it should be noted that any conventional drive means could be employed for this purpose, such as hydraulic cylinders interconnecting the adjacent links such that when they are simultaneously actuated to extend their piston rods they cause a clockwise rotation (with reference to Fig. 10) from the bundle forming position of Fig. 10 to a substantially flat condition forming an extension of the plat- form 71' and such that when they are simultaneously actuated to retract the piston rods they cause the link systems to return to the illustrated bundle forming position.

The platform unit T of this second embodiment is essentially identical to that of the first embodiment although the platform 71' in itself is slightly modified, mainly in view of the diffe- rent position of the bundling tunnel 80' and the journals for the pivotal link system 81' and the shafts 83 'a and possibly 85'. It should be emphasized that in this embodiment also the platform 71 ' is formed of plates covering the distances between the bars of the framework, although said plates have been removed in figs. 7-9 in order to provide a better illustration of the framework of the platform unit T .

In this second embodiment the platform 71' is provided with a guide member consisting only of the first section 74'a whereas the tunnel conveyor chains do not run in any guides. However, protective covers 87 are provided externally of the chain sets 82', said covers being separated for allowing for the pivotal movement but in effect being connected to each other by means of not illustrated rubber bellows to thereby have the functional design appearing in figs. 7 and 8 offering full protection against injury by the chains. Preferably all of the chains of the second embodiment, i.e. the platform conveyor chains 73', possibly the drive transmitting chain 86' and all of the chains in the chain sets 82' are of the same kind as the platform conveyor chains 73' illustrated and described in connection with the first embodiment, i.e. being equipped with driver members which are not specifically illustrated in Figs. 7-10.

The main advantage of the described second embodiment is that bundles of variable diameter may be formed but this embodiment also adds to the flexibility of the bundling apparatus 1'. More specifically the apparatus may be employed in the following manner. When a field is to be harvested the bundling tunnel 80' is unfolded so as to form a flat continuation of the plat- form 71' either for receiving plants to be used in full lengths for instance for planting, or for harvesting a section of the field until the platform is full and then returning to a specific location where the bundling tunnel 80' is folded again and the sideways conveying is started for forming bundles of the collected material at said specific location so that they will not have to be picked up on the field. When the platform is emptied the tunnel 80' is unfolded and harvesting is resumed.

Although the invention has been described herein with reference to specific embodiments thereof, it should be obvious that the invention also comprises variations and modifications that are obvious to a man skilled in the art. Thus, although the invention has been described herein solely with regard to an apparatus for harvesting plants and feeding them onto the platform, it should be obvious that the basic principle of the invention is also applicable to a stationary bundle forming apparatus in which woody plants are manually or otherwise loaded onto the platform in order to be conveyed sideways into the bundling unit. Likewise, the invention is not restricted to the specific embodiments of the drive means, conveyor means and so forth that are described and illustrated with reference to the illustrated embodiments, but it should be obvious that equivalent means could be employed instead thereof. Therefore, the scope of the invention should only be determined by the scope of the enclosed patent claims.

Claims

PATENT CLAIMS

1. A method of bundling woody plants, said plants being sucessively fed to and gathered in a bundling unit (8, 8') where the plants and the continous bundle being formed are subjected to a rotary movement and a simultaneous substantially linear movement in the longitudinal direction (B; B') of the continous bundle being formed, characterized in that the plants are fed onto a supporting plane (7, T) on which they are engaged and conveyed in a direction (D) generally transversal to the longitudinal extension of the plants and sideways into the bundling unit.

2. A method according to claim 1, characterized in that the plants are fed onto the supporting plane (7, T) in a plant infeed direction (A) generally transversal to the plant conveying direction (D) on the supporting plane (7, 7') and in that the bundle being formed is fed out from the bundling unit (8, 8') in a bundle discharge direction (B; B') likewise generally transversal to said conveying direction (D) and substantially opposite said plant infeed direction.

3. A method according to claims 1 or 2, characterized in that at least said bundle discharge direction (B) forms an obtuse angle with the conveying direction (D).

4. A method according to claims 1 or 2, characterized in that at least said bundle discharge direction (B') forms a right angle with the conveying direction (D).

5. A method according to any of claims 1-4, characterized in that the plants are fed onto the supporting plane (7; 7') positioned with their root ends in a predetermined substantially fixed position, rearwardly on the supporting plane, with respect to said plant infeed direction (A).

6. A method according to any of claims 1-5, characterized in that the bundle is formed having a variable diameter in an adjustable width bundling unit (8').

7. An apparatus (1; 1') for bundling woody plants, having a bundling unit (8; 8') and conveyors (73; 73', 82') for conveying the plants into the bundling unit and for subjecting the plants and the continous bundle being formed to a rotary movement and a simultaneous substantially linear movement in the discharge direction (B; B') of the continous bundle being formed, characterized by a supporting plane (7; 7') on which the plants are supported, in that the plant conveyors are extended in a direction (D) generally transversal to the longitudinal extension of the plants on the supporting plane and to said direction (B; B') of the continous bundle and in that the bundling unit (8, 8') comprises a bundling tunnel (80; 80') extending generally transversal to the extension of the plant conveyors and provided with an infeed opening (81) for feeding the plants sideways into the bundling tunnel.

8 An apparatus (1 ; 1) according to claim 7, characterized by an infeed unit (5) for feeding the plants onto the supporting plane in an infeed direction (A) being substantially opposite to the bundle discharge direction (B, B').

9. An apparatus (1) according to claim 7 or 8, characterized in that the bundling tunnel (80) has the shape of a hollow cylinder supported on the supporting plane (7) and in that a section of the peripheral wall of the cylinder is removed along the full length thereof, forming the infeed opening (81).

10. An apparatus (1) according to any of claims 7-9, characterized in that the supporting plane (7) is formed by a platform (71), in that said conveyors (73) are endless conveyors extending partially in the supporting plane of the platform and partially along the inner periphery of the bundling tunnel (80).

11. An apparatus (1) according to claim 10, characterized in that the conveyors (73) along the platform (71) run in a first plane (D) substantially perpendicular to the supporting plane of the platform (71) and to the longitudinal extension of the plants, and along the inner periphery of the bundling tunnel (80) run in a helical path.

12. An apparatus (1) according to any of claims 7- 11, characterized in that the centre axis of the bundling tunnel (80) and thereby the bundle forming direction (B) forms an obtuse angle with the direction (D) in which the plant conveyors (73) are extended.

13. An apparatus (1 ') according to claim 7 or 8, characterized in that the bundling tunnel (80') is adjustable with regard to its inner, bundle forming cross section.

14. An apparatus (1') according to claim 13, charact erized in that the bundling tunnel (80') is is adjustable to a flat condition, forming a continuation of the supporting plane (7').

15. An apparatus (1') according to claim 13 or 14, c h a r a c t e r i z e d in that the supporting plane (7') is formed by a platform (71'), in that said conveyors (73', 82') are endless conveyors of which a number of first conveyors (73') extend partially in the supporting plane of the platform and a number of sets of second conveyors (82') extend partially along the inner periphery of the bundling tunnel (80').

16. An apparatus (1') according to claim 15, c h ara c t e r i z e d in that the first conveyors (73') along the full extent thereof run in one first plane substantially perpendicular to the supporting plane of the platform (71') and to the centre axis of the bundling tunnel (80') and thereby to the bundle discharge direction (B') and in that said second conveyors (82') each run in planes inclined with regard to said second plane.

17. An apparatus (1; 1') according to any of claims 8-16, characterized in that the infeed unit (5) consists of two infeed conveyors (51, 52) separated by a plant receiving and conveying space (56) and has an infeed end (53) spaced from the supporting plane (7; 7') and an output end (54) positioned generally centrally, with respect to the infeed direction (A), above the supporting plane.

18. An apparatus (1; 1') according to claim 17, characterized in that the infeed conveyors (51, 52) each are provided with an upper and a lower endless conveyor member (58 and 59, respectively) positioned one above the other, at a distance from each other.

19. An apparatus (1; 1') according to claim 18, characterized in that the mutual distance between the upper and lower conveyor members (58 and 59, respectively) of each infeed conveyor (51, 52) decreases gradually from the infeed end (53) of the infeed unit (5) towards its discharge end (54).

20. An apparatus (1; 1') according to any of claims 7 -19, characterized in that the plant conveyors (73; 73', 82') consist of conveyor chains being provided with drivers (73b) for engaging the plants.

21. An apparatus (1; 1') according to any of claims 18 -20, characterized in that the upper and lower conveyor members (58, 59) of the infeed unit (5) consist of conveyor chains being provided with drivers 63 for engaging the plants.