CA2056333A1 - Feed arrangement for a harvester - Google Patents

Abstract

ABSTRACT

An arrangement for the feeding and guiding of tree trunks in conjunction with the delimbing of the trunk operates with moving feed belts 22 arranged opposite one another on either side of the trunk, which feed belts drive the tree trunk by friction in its longitudinal direction through a delimbing unit, where branches are removed from the tree.
the feed belt is in the form of an endless belt which is attached along its lateral edges 23 to drive chains 20 engaging with toothed rings 24 on two separate feed wheels 7. A rectilinear section of the feed belt is held under pressure in flexible contact with the trunk 1 as friction is developed over a relatively large area.

The large friction surface between the feed belt and the trunk means that the necessary force for feeding the trunk can be achieved without the risk of damage to the surface layer of the trunk.

Description

Sgn/RL/2538~ z~5333 Feed arrangement or a harvester Roy present invention relates to an arrangement for the feeding and guiding of tree trunks in logging machines comprising two interacting moving friction webs in the form of feeding belts which are in contact with the tree trunk on opposite sizes of -the trunk.

Mechanized timber felling makes use of suckled harvesters, whose task is to cut the tree intended for felling at the root, and then to remove branches from the tree and to cut the tree trunk into convenient lengths. The feeding of the tree trunk for delimbing presents certain problems in this respect. The delimbing operation itself is performed with the help of delimbing knives, which follow the tree trunk and against which it is fed butt end first.
Testing has revealed that considerable force is required for the feeding operation, partly in order to overcome the resistance of the delimbing itself, i.e. the cutting of of the brunches from the tree, and partly in order to overcome the frictional forces and accelerating forces which arise.
One major problem associated with felling using harvesters has its background in the requirement for the rapid feeding of the tree trunk without damage being caused to the bark or the surface layer of the trunk. In order to avoid damage to the trunk, the bark layer must remain undamaged as far as possible. Partial barking of the trunk loads to uneven drying out and cracking during storage of the timber. The so-called spiked rollers which were used previously suffer from disadvantages due to their tendency to slip and to cause damage in other respects to the surface layer of toe trunk. feud wheel with a friction web of rubber in ,, : , 2 So combination with an anti-skid device in the form ox chain elements to some extent avoids the aforementioned disadvantages associated with the previously used spiked rollers, although weed wheels of this wind also suffer from S shortcomings due to their small friction surface and the high wear on the rubber web, one consequence of which is high costs.

lo previously disclosed is the equipmen~.of the harvester with a so-called belt feed system. In this case the tree trunk is fed with the help of moving belts which make contact with the trunk under the effect of friction. In order Jo achieve an adequate friction surface with the help of these essentially flat belts, the belts are equipped with spikes or combs to provide increased grip on the trunk. Damage to the trunk similar to that caused by the use of spiked rollers occurs in this case, too.

Feed wheels with a friction web consisting of chain netting, either alone or in combination with an elastic support web in accordance with Patent applications SE-8902493-3 and SE-9000590-1, have been found to produce a significant improvement in that the friction web of the feed wheels is able to adapt with greater flexibility to the form of the tree trunk as it passes through the harvester as the diameter reduces progressively towards the top end of the trunk. These feed wheels are nevertheless still beset by the fundamental problem what the feed wheels are required to exert a relatively high frictional force against the trunk in order to feed it at the required speed. Since the feed wheels are in contact wit the trunk only over a limited area, it is necessary Jo exert a considerable force against the trunk in order to produce the required frictional o'er. It is necessary at all times, however, to take into account the risk of slipping and surface damage to the trunk The object of the present invention is to eliminate the aforementioned disadvantages and to make available a feed arrangement which ensures the necessary feed force whilst exerting a relatively low specific surface pressure against the trunk. This is achieved by a feed arrangement of the kind indicated by way of introduction through the characteristics in accordance with the accompanying Patent Claim 1.

Because the contact pressure of the feed belt against the trunk is distributed over a relatively large area, the specific contact pressure will be relatively low, even if a considerable frictional force is exerted in full between the feed belt and the trunk. The concentrated application of force against the trunk, with the associated risk of damage to it, is avoided in this way.

The feed belt is flexibly supported on the feed wheels and is attached along each of its free edges to a drive chain intended to engage with the respective toothed rings on each feed wheel. In order to achieve the desired flexibility of the feed belt, the toothed rings are non-pivotal mounted on the shafts of thy feed wheels, but in a manner which permits their axial displacement.
alternatively, only one ox the toothed rings may be capable of axial displacement. By changing the axial distance between the toothed rings, the feed belt can be made to adapt to the varying diameter of the tree trunk.

The tree trunk is fed in its longitudinal direction with the help of the fee belt, which is set in motion with the help of a hydraulic motor connected to each feed wheel.

In order to facilitate the adaptation of the feed belt to varying diameters of the tree trunk, the wheel discs ox the feed wheels with their associated toothed rings may be 4 I 33~

connected to the drive shaft of the feed wheel via a threaded union. These threaded unions have a mutually opposing pitch arranged in such a way that the wheel discs are screwed towards one another under -the rotating load from the shaft of the feed wheel until the weed belt between the wheel discs develops sufficient contact pressure to counteract the rotation of the wheel discs relative to the shaft, that is to say in such a way that the wheel discs are caused to rotate in the same direction as the shaft and to feed the trunk via the belt.

In this, as in the preceding form of execution, spring devices in the form of cup springs (Belleville spring washers) are fitted between the wheel discs with the effect of forcing the wheel discs in a direction away from one another. because the wheel discs in the last-mentioned form of execution are connected to the drive shaft ox the feed wheel via threaded unions, the distances between the wheel discs will be adapted in such a way that the feed belt has its largest contact surface at the hull end of the trunk, where the maximum feed force is required, whereas the distance between the wheel discs is increased towards the top end of the trunk, where a smaller feed force is required. This automatic adjustment of the wheel discs and the feed belt maps it possible to achieve effective feeding of the tree trunk even where there is a considerable difference in diameter between the butt end and the top end, but without the wheel discs on the feed wheel coming into contact with one another.
us an alternative to threaded unions, the use ox tooth couplings in which one half of the coupling is attached to the drive shaft of the feed wheel and the other half is attacked to the wheel disc is also conceivable. the teeth of the coupling are executed in this way with the engagement flanks of the teeth inclined at an angle to the Jo 3~3 axis of the coupling such that the tooth coupling operates in a corresponding fashion to the threaded union described above, that is to say an axial displacement of that half of the coupling which is connected to the wheel disc takes place above a certain torque level.

The feed belt included in the arrangement may vary in its execution. Use may thus be made of a chain net of familiar execution, with runs of chain intersecting one another and connected to one another at the points of intersection, which runs of chain extend, for example, at opposing angles of inclination to the longitudinal direction of -the feed belt. Any other chain pattern which permits appropriate adaptation to the tree trunk may also be used, however. Of particular interest as an alternative to the chain net are feed belts consisting of intersecting bands of steel which extend a mutually opposing angles of inclination to the longitudinal direction of the feed belt and are attached to its drive chains. In order to permit the unhindered adaptation of the feed band formed in this way as it changes its form as it passes over the feed wheels, these metal bands are attached only at their ends to the drive chains and are free to move relative to one another at the points of intersection.
It is appropriate and desirable in many cases to provide the elements of the feed belt with an elastomers coating.
If necessary, this coating ma be executed in the Norm of a continuous strip into which the chain net or the aforementioned steel bands are mounded.

the invention is described below in the form of illustrative embodiments and with reference to the accompanying drawings.

3~3 Figure 1 is a schematic end view of a harvester viewed in the direction I-I in Figure 2. Figure 2 shows the unit in schematic plan view. Figure 3 is a side view of a feed wheel belonging to the harvester in the laden condition.
Figure 4 shows the feed wheel in contact with a tree trunk.
Figure 5 is a partially sectioned plan view of the feed wheel in accordance with Figure 4. Figure 6 is a partial side view of the friction web with drive chains connected viewed along the line VI-VI in Figure 5. Figure 7 shows a further embodiment of the feed wheel with the wheel discs connected via threaded unions, to a larger scale. Figure 8 shows the schematic engagement between a feed wheel and the top end of a tree trunk.

Figures 1 and 2 illustrate schematically a harvester 2 for feeding a tree trunk 1 in the direction of the arrow shown in Figure 2. The unit has a cutting unit 3 for cutting the actual tree, a feed arrangement 4 for feeding the tree trunk, and a delimbing unit 5 for the purpose ox removing the ranches of the tree as the tree trunk is fed through.
The cutting and delimbing units are previously disclosed elements and are not discussed in any greater detail in this context.

Mounted on the frame 6 of the harvester are two feed arrangements 7, 7 intended to be forced against each side owe the tree trunk 1. Each feed arrangement is articulately supported at coupling points 10 via arms 9, 9 and bearing shafts 11 on the frame 6. The arms 9 are able to pivot tout the respective shaft 11 and are connected at their ends which face away prom the feed wheels via points ox articulation 13~ 13 to the opposite ends of a pressure cylinder 12. The two feed arrangements 7, 7 with their associated arms are symmetrical in relation to the centre-line of the trunk 1. The arms 9, 9 are caused Jo pivot about the shafts 11, 11 by the expansion of the pressure 7 ~S33~S

cylinder 12, so that the feed arrangements 7, 7 are forced against the trunk 1.

Each feed arrangement comprises two feed wheels 7, 7. The execution of the feed arrangement can be appreciated in more detail from Figures 3 to 6. Each feed wheel is constructed around a central shaft 16 which is rotatable supported in bearings on upper and lower supporting plates 8, which form the supporting structure for the feed wheels.
The supporting plates are articulately connected to the respective arms 9 at the aforementioned coupling points 10. The shaft 16 ! which is rotatable mounted in the supporting plates 8, supports a feed wheel 7 consisting of an upper and a lower wheel disc 15. These wheel discs are non-pivotally mounted, for example Bohemians of splints 17 on the shaft 16, and are capable of axial displacement on that shaft. Present between the two wheel discs is a set of cup springs (Belleville spring washers) 19, the effect of which is to force the wheel discs in a direction away from one another. In the position shown in Figure 3, the wheel discs are in contact with respective bearing bushings in the supporting plates 8.

The wheel discs 15 are executed at their periphery in the form of toothed rings intended to engage with the respective drive chains 20 which link together the feed wheels 7, 7 in each pair. feed belt 22 in the form of an endless belt extends between the drive chains for each pair of feed wheels. The drive chains are illustrated in the Figure as roller chains, although any other type of flat link chain can be used. The feed belt illustrated is executed in thy form of a chain net a SO-called diagonal net is shown in the Figure - although the feed belt can also consist of a chain net to some other pattern which is suitable for forming a support web and can be connected to any drive chains I which may be present. The feed belt can also be constructed from intersecting bands of steel or some other suitable metal, which bands extend at respective opposing angles of inclination to the longitudinal direction of the feed belt. In order to permit the necessary adaptation of the belt as it moves in the feed web, the individual elements of the belt are connected to the drive chains only at their end points and not to one other at the points of intersection. The roller chain 20 shown in Figure 6 is connected to the lateral edge 23 of the chain new with the help of clamps 21.

In order to feed the trunk 1, one of the feed wheels 7 in each pair to either side of the trunk is caused to rotate with the help of, for example, a hydraulic motor 18. m e linking together of the two feed wheels in each pair with the help ox the drive chains 20 ensures the even and equal feeding of the two edges of the chain net.

Figure 3 shows the feed belt in the Walden condition. When 70 the feed heel is forced against the! trunk 1, as shown in Figure 4 (a corresponding feed wheel is assumed to be arranged symmetrically on the opposilce side of the trunk), the feed belt 22 will be forced in towards the centre ox the feed wheel, in conjunction with which the belt 22 draws the two wheel discs 15, 15 towards one another under axial guidance in the splinted union 17. The feed belt I now comes into approximate contact with the surface of the trunk 1 under the effect of friction against it. When the feed belt is extending essentially in a rectilinear fashion along the trunk 1 for a distance corresponding to the distance between the shafts of the feed wheels, a considerable friction surface is produced between the net and the trunk. This friction surface ensures the necessary frictional force for feeding the trunk, even at a relatively low specific surface pressure. The risk of surface damage to the trunk is avoided in this way. The axial adjustment of the two wheel discs of the feed wheel ensures that the chain net adapts appropriately to the form of the trunk.

on embodiment in accordance with Figure 7 can be applied with advantage in order further to improve the attachment of the friction web to the tree trunk, and to permit the feeling of tree trunks with a considerable difference in diameters between the butt par and the top part. The same reference designations as in the above embodiment are used in Figure 7 for identical parts of the arrangement.

according to Figure 7 the shaft 16 is rotatable, as in the previous embodiment, with the help of a motor 18 and is guided in bearings on the support plates 8, 8. attached to the shaft 16 in this case are threaded sleeves 25, which engage via threaded unions 29 with the respective wheel discs 26. These threaded unions have mutually identical but opposing pitches. The threads in the union are preferably square threads or trapezoid threads with the ability to absorb a high axial load. A spacer sleeve 26 is inserted between the threaded sleeves US, I spring device 19 lion example, a sex of cup springs (Belle~ille spring washers)) between the wheel discs 26,-26 exerts an axial force against the wheel discs 26, 26 via spacer washers 28 in a direction such as to move these aware from one another.

Toe l~ft-hand half of Figure 7 shows the eddy wheel with the wheel discs in their outer end position with the chain net 22 extended between the wheel discs. The right-hand halt of the Figure shows the feed wheel during engagement with a tree trunk with the feed wheels brought together against the effect of the spring device 19 to a position in which the feed belt 22 is essentially in contact along its rectilinear part with the tree trunk.

I

This arrangement works in the following way. It is assumed that a corresponding feed wheel engages with the trunk 1 on the right-hand side.

In the initial position in accordance with the left-hand half of Figure 7, the linked pair of feed wheels with the rectilinear net part extended between them is brought into contact with the trunk 1. The shaft 16 with the threaded sleeves 25, 25 rotates. During a starting phase, the wheel discs with the net in contact with the trunk remain in position without the wheel discs rotating, whilst the wheel discs are brought towards one another by means of the threaded unions 29 and compress the spring device 19.
Further displacement of the wheel discs and compression of the spring device finally leads to a position of equilibrium in which the peripheral component of the force transferred to the wheel disc is sufficient to cause the wheel disc to rotate and, by so doing, to advance the trunk 1. The pitch of the opposing threaded unions 29 and the execution and the sliding friction in the threaded union require to be adapted in this case in relation to the developed spring force, in such a way that the desired feed force is obtained at the adjusted axial distance between the wheel discs.
us mentioned above, the required feed force is greatest at thy butt end of the trunk, as it it necessary at this point to take account of significant acceleration of the tree and frictional losses with the ground, etch The fact that the wheel discs 26 are moved closer together, because of the relatively greater feed resistance as the weed wheel is applied to the butt end of the trunk, means that the friction web moves into relatively close contact with the surface of the trunk during the starting phase of the feed, which is advantageous for the uniform distribution of the contact pressure of the net against the trunk.

So it the end of the weed operation, on the other hand, when the necessary feed force is significantly reduced, the wheel discs will be moved further apart under the effect of the spring device 19, which is possible because the threaded union is not self-bra~ing. As will be appreciated from Figure I the friction web 22 will be extended in this way, and the distance between the periphery of the feed wheels 26 will be extended. The risk of the weed wheels approaching too closely to one another or coming into contact with one another is avoided in this way if a trunk of low diameter is fed through.

The feed wheels thus adapt themselves automatically to the force required for feeding a trunk of varying diameter.
In a simplified alternative it is also possible to attach one of the wheel discs 26 securely to the shaft 16 of the feed wheel, whilst the other wheel disc is supported as shown in Figure I above. The feed wheel in this case operates in principle in the same way as described above, although the height of the trunk 1 changes us the axially movable wheel disc 26 is adjusted. This may be observed as the trunk is guided through the harvester.

us can be appreciated from the foregoing, the friction web in contact with the trunk as it is being fed can exhibit different executions. Where high demands are imposed with regard to the surface of the processed trunk, a friction web consisting of a supporting layer which is mounded into a suitable elastomers such as rubber, or a plastic material of adequate softness, etc., is preferred The supporting layer then consists of a chain net or, alternatively, of intersecting band elements, for example, in conjunction Whitehall which the supporting elements of the layer either can be coated separately with an elastomers or can be included in an elas~omer strip in the form of moulded-in reinforcing elements. In those cases in which no special requirements are imposed on the surface of the processed trunk, a chain net, for example, can form the friction web directly without any special coating.
S

Claims (9)

1. An arrangement for the feeding and guiding of tree trunks in logging machines comprising two interacting feed belts (22) capable of moving in a direction parallel with the trunk, each of which belts forms a friction web running over two separate and axially parallel feed wheels (7) which is in contact with the trunk (1) along a rectilinear extended section of the friction web on the respective opposite sides of the trunk, characterized in that the feed belt (22) forms a flexible, elongated contact surface which, under the effect of pressure against the trunk (1), endeavours to adapt itself to the form of the trunk and, after said pressure is removed, endeavours to revert to essentially plane form.

2. Arrangement in accordance with Claim 1, characterized in that the feed belt (22) is attached along each of its free lateral edges (23) to an endless drive chain (20) intended for engagement with a toothed ring (24) respectively on first and second concentric wheel discs (15, 26) which are capable of axial adjustment relative to one another for each feed wheel (7).

3. Arrangement in accordance with Claim 2, characterized in that both wheel discs (15) for each feed wheel (7) are so arranged as to be displaced by the use of previously disclosed coupling devices in a non-pivotal and in an axially floating fashion on the shaft (16) of the feed wheel, in conjunction with which axially acting spring devices (19) cause the wheel discs to move in a direction away from one another.

4. Arrangement in accordance with Claim 2, characterized in that a first wheel disc for each feed wheel is rigidly attached to the shaft of the feed wheel, whilst a second wheel disc is attached by the use of previously disclosed coupling devices in a non-pivotal and in an axially displaceable fashion to the shaft of the feed wheel, in conjunction with which axially acting spring devices (19) cause the wheel discs to move in a direction away from one another.

5. Arrangement in accordance with Claim 2, characterized in that both wheel discs for each feed wheel (7) are attached to the drive shaft (16) of the feed wheel via a threaded union (29) arranged concentrically with the drive shaft and comprising an externally threaded sleeve (25) rigidly attached to the drive shaft in engagement with a corresponding internal thread on the wheel disc (26), in that these threaded unions exhibit mutually opposing pitches arranged in such a way that a torque developed by the drive shaft (16) for the purpose of feeding the tree trunk endeavours to move the wheel discs (26, 26) in a direction towards one another under the relative movement of the engaging component parts of the threaded union, in that spring devices (19) cause the wheel discs (26, 26) to move apart in an axial direction, and in that the threaded unions are not self-braking when exposed to an axial load.

6. Arrangement in accordance with Claim 2, characterized in that a first wheel disc for each feed wheel is rigidly attached to the drive shaft of the feed wheel, whilst a second wheel disc (26) is attached to the drive shaft (16) of the feed wheel via a threaded union (29) arranged concentrically with the drive shaft and comprising an externally threaded sleeve (25) rigidly attached to the drive shaft in engagement with an internal thread on the wheel disc (26), in that the threaded union exhibits a direction of pitch such that a torque developed by the drive shaft (16) for the purpose of feeding the tree trunk (1) endeavours to move the wheel disc attached via the threaded union (29) in a direction towards the rigidly attached wheel disc under the relative movement of the engaging component parts of the threaded union, in that spring devices (19) cause the wheel disc (26) attached via the threaded union to move away from the rigidly attached wheel disc in an axial direction, and in that the threaded union is not self-braking when exposed to an axial load.

7. Arrangement in accordance with any of the preceding Claims, characterized in that the feed belt is in the form of a chain net consisting of links which engage with one another.

8. Arrangement in accordance with any of the preceding Claims, characterized in that the feed belt is in the form of intersecting bands of steel or some other metal which are able to move relative to one another at the points of intersection, which bands extend in respective opposing angles of inclination to the longitudinal direction of the feed belt.

9. Arrangement in accordance with any of the preceding Claims, characterized in that the supporting chain or band elements of the feed belt are provided with a coating of elastomer, or are moulded into a continuous strip of elastomer.