WO2002021906A1

WO2002021906A1 - Link mechanism for harvesting head

Info

Publication number: WO2002021906A1
Application number: PCT/FI2001/000790
Authority: WO
Inventors: Kari Hanne
Original assignee: Timberjack Oy
Priority date: 2000-09-15
Filing date: 2001-09-12
Publication date: 2002-03-21
Also published as: FI20030216A; SE0300429D0; FIU20000360U0; SE0300429L; FI122910B; AU2001285975A1; FI4695U1; SE524224C2

Abstract

A link mechanism for a harvester head, the harvester head comprising at least a swivelling arm (1), by means of which the frame (2) of the harvester head is arranged to be suspended in the boom assembly of a working machine, and a link mechanism (10) which is arranged to couple the swivelling arm (1) to the frame (2) and to pivot them in relation to each other around a horizontal axis (Z). The harvester head also comprises actuator means (3) for pivoting, to provide a force effective between the frame (2) and the swivelling arm (1). The link mechanism (10) comprises a shaft (11, 13) to be placed on the axis (Z), the frame (2) being coupled to the shaft in a freely rotating manner and the swivelling arm (1) being connected to the frame in a non-rotating manner. The shaft (11, 13) is arranged to be rotated by means of actuators (3) in relation to the frame (2) and to transmit a force effect via said shaft (11, 13) also to the swivelling arm (1) for pivoting.

Description

Link mechanism for harvesting head

The invention relates to a link mechanism for a harvesting head according to the preamble of claim 1.

For the processing of tree trunks, a harvester head is used for the purpose of gripping an upright growing tree, to cut the tree and to fell it for delimbing and cutting the trunk into pieces of fixed length. The head is normally fixed at the end of a boom assembly in a working machine, such as a harvester, which is movable on a terrain by means of wheels or a crawler. Some harvester heads are also used for the processing of the trunk during loading, wherein they are also provided with grapple means tumable with respect to the frame structure pairwise on different sides of the trunk. The harvester head comprises the necessary actuator means, normally hydraulic cylinders and hydraulic engines which can be used to control the position of the head and the different functions. The head, which, in the following description, will also be referred to as the delimbing apparatus, also comprises delimbing means which can be swivelled in relation to the frame structure, nor- mally pairwise on different sides of the trunk. The delimbing means comprise delimbing blades to cut off the branches while the trunk is being carried and transported through the apparatus. Feeding means, normally also pairwise on different sides of the trunk, normally comprise a feed pulley or a feed roll which is driven by a hydraulic motor, is pressed against the trunk, and pulls it past the delimbing blades and through the apparatus. The head is also provided with cutting means, such as a chain saw, for cutting the trunk.

For the suspension of the delimbing device, a rotatable link, or rotator, is used in a known manner. By means of the link, the head hanging at the end of a boom in the working machine can be swivelled in a controlled manner around a substantially vertical axis. At the same time, the link and the head can swing together and rotate freely around at least one substantially horizontal axis, supported by a free link. The head is connected to the link by means of a swinging arm or a tilt arm, by which, and controlled by the actuators, the head can be turned to a vertical felling position to grip a growing tree and to a horizontal de- limbing position for delimbing or other processing of the trunk. Supported by the tilt arm, the frame of the head is swivelled around a substantially horizontal axis.

One delimbing device and tilt arm with its actuators are presented in the patent publication US 5,975,168, in which the turning cylinder is coupled between the frame of the harvester head and the tilt arm. For floating of the head freely in the horizontal position, the cylinder is let to shorten. When pressurized, the cylinder is lengthened and it simulta- neously turns the frame structure upright. Another delimbing apparatus with a tilt arm is presented in the application publication WO 99/35901 , in which the cylinder is allowed to lengthen for moving of the head freely into the horizontal position. When pressurized, the cylinder is allowed to shorten and it simultaneously turns the frame structure up- right. The tilt arm normally comprises two adjacent arms, and each of them can be coupled to a swivelling actuator for symmetrical loading. At their upper ends, the arms are connected to each other by means of a welded structure. At their lower ends, the arms are connected to the frame by means of a joint.

The mounting points of the cylinder actuators, the mounting lugs and their placement in the tilt arm, as well as the joint arrangements are problematic with respect to space utilization and structural strength. It is particularly difficult to design the welded structures to resist tensions and to have sufficient fatigue strength. The tilt arm is loaded by the weight of the harvester head, which may total about 800 to 1400 kg, and also by the weight of the trunk to be carried, which may be about 400 kg/m³. The loads are increased by the swinging of the head and the trunk during the delimbing and the felling.

It is an aim of the present invention to eliminate the drawbacks presented above by means of a new link mechanism in the swinging arm. To achieve these aims, the link mechanism according to the invention is characterized in what will be presented in the characterizing part of the appended claim 1. By the invention, a simpler structure for the swinging arm is achieved, since there is no need to form or fix extra lugs in the swinging arm e.g. for cylinders or bearings. It is possible to avoid welded structures related to the swinging arm which would have a harmful effect on its tensions and loads. For a pivoting movement, only one actuator will be needed, for example a hydraulic cylinder which is centrally placed inside the swinging arm in a protected manner. The actuator is now also placed in a location closer to the frame where it is better protected. The link mechanism is used to achieve a symmetrical loading on the link shaft and on the swivelling arm.

A significant advantage is that the link mechanism and the mounting of the actuators will only limit the design of the swinging arm with respect to how it is connected to the link shaft shown. In other respects, the swivelling arm structure can be selected more freely to be suitable with respect to e.g. strength, dimensions, weight or processibility.

An advantageous embodiment of the invention has the significant advantage of easy mounting. This is achieved, for example, by means of an link shaft provided with an external grooving and by means of accessory parts provided with an internal grooving. With the grooving, the accessory parts can be fitted on the shaft by gliding, but simultaneously their rotation with respect to each other is prevented by means of the grooving. The actuator is a simple cylinder which per- forms a reciprocating stroke and which is connected to a lug at a distance from the rotation axis. This yields the required moment effect changing the angular position between the swivelling arm and the frame.

In the following description, the invention will be illustrated with reference to the appended drawing which shows a link mechanism according to an advantageous embodiment of the invention in an exploded view and applied in connection with a swivelling arm.

The figure shows a tilt arm or swivelling arm 1 in the harverster head, being substantially fork-like and comprising two adjacent parallel vertical arm parts 1 a and 1b, to whose lower ends the frame 2 of the harvester head is connected by means of the link mechanism 10 according to the invention. To the frame 2 are connected the other actuators of the harvester head, such as feeding, delimbing and felling means. The more detailed structure and selection of actuators may vary, comprising, for example, also grapple means. In a stroke delimber, feeding wheels or rolls used as the feeding means can be replaced by a reciprocating motion. The frame is only illustrated with a broken line 2, to which the cylinder used as the actuator 3 is connected at its one end by means of a joint.

The upper ends of the arm parts 1 a, 1 b are connected by a bridge part 1c, at which it is suspended to the end of the boom assembly of the working machine. To the swinging arm 1 is connected a rotator 4, known as such, which allows the rotation of the swivelling arm 1 around a vertical rotation axis Y. Further, the rotator 4 is freely suspended to the end of the boom assembly, wherein the rotator, and simultaneously the swivelling arm 1 and the frame 2, are allowed to swing around a horizontal rotation axis X. It is obvious that the structure of the swivelling arm 1 may be different from that presented.

The link mechanism 10 according to the invention is arranged to couple the swivelling arm 1 to the frame 2 and to pivot them in relation to each other around a horizontal axis Z. The force effect needed in the pivoting is produced by actuators 3, such as a single-acting or double-acting cylinder 3 driven by pressurized medium. Centrally on the axis Z is fitted a parallel shaft structure which, according to an advantageous embodiment, is a shaft bar 11 , around which the frame 2 can be freely rotated, controlled by the actuators 3. On the other hand, the shaft bar 11 is connected to the arm elements 1a, 1b in such a way that the shaft bar 11 and the swivelling arm 1 cannot rotate in relation to each other around the line Z. Consequently, the swivelling arm 1 rotates with the shaft bar 11 when it is rotated, and vice versa.

The shaft bar 11 is rotated by the moment force of the actuators 3. The torsional moment is fully transmitted to the shaft bar 11 which divides and transmits the moment to both arm elements 1a, 1 b via the mountings 1d, 1e of the swivelling arm 1. The arm elements 1a, 1 b are plate structures made of steel, extending in a direction perpendicular to the line Z.

The outermost first end 11 a of the shaft bar 11 is provided with fixing means 11 b for the swivelling arm 1 and the mounting 1b. The means 11b comprise a perpendicular flange 11 b fitted centrally to the line Z for the screw mounting of the flange 11b. The flange 11b is mounted inside the arm element 1b, between the arm elements 1a and 1 b. Next to the flange 11 b, closer to the second end 11 c, there is also a centrally fitted cylindrical glide surface 11d for slide bearing. The slide bearing forms the necessary bearing means for the frame 2. Around the surface 11d is fitted a cylindrical bushing 12, whose inner surface is used as a second glide surface. Around the bushing 12, in turn, is fitted the mounting of the frame 2, for example a lug with an opening for the bushing 12. It is obvious that the mounting may vary according to the frame structure, and also the more detailed structure of the bushing 12 may vary. The different structures can be implemented by anyone skilled in the art by techniques known as such. The principle is, however, that the frame 2 is supported by the shaft bar 10 at the glide sur- face 11 d as well as at the glide surface 13b.

For the sake of clarity, the parts 11 and 13 are placed outside the arms 1a, 1b in the figure, but in the final assembly, they are placed between the arms 1a, 1b, as well as the bushings 12 and 14.

Around the shaft bar 11 , at its second end 11c, also extending through the middle part, an external and longitudinal grooving 11 e is cut, parallel with the line Z. The grooving 11 e is intended for the transmission of the rotational motion, wherein a grooving with a corresponding pitch is made inside that part which is placed around the shaft bar 11 and which is intended to rotate with the shaft bar 11. The parts can, however, glide along the shaft bar 11 in the direction of the line Z, wherein the mounting is easy. This kind of a part is a separate shaft part 13 which is symmetrically provided with mounting means 13a corre- sponding to the mounting means 11b for the arm element 1a and the mounting 1d, and a glide surface 13b corresponding to the bearing means 11d for the frame 2. The bushing 14 to be placed on the glide surface 13b corresponds to the bushing 12. The part 13 is placed around the end 11c of the shaft bar 11 and is locked in its position by means of a spacer 15 and a bolt 16 which is fixed inside the end 11 c.

Around the shaft bar 11 , in its middle part, it is also possible to mount a turning sleeve 17 for rotating the shaft bar 11. As described above, the sleeve 17 is a part equipped with an internal grooving. The sleeve 17 is rotated in relation to the frame 2 to transmit the rotational motion by means of the shaft bar 11 also to the swivelling arm 1 via the mount- ings 1d, 1e and further the arms 1a, 1 b. In this way, it is possible to accomplish pivoting of the harvester end to the upright position, either by shortening or extending the cylinder 3. The sleeve 17 is provided with lugs 17a and 17b for the cylinder 3. The cylinder 3 is mounted between the lugs, supported by a pin 18. The lugs 17a, 17b constitute a joint whose rotation axis is parallel with the axis Z but at a distance from it. By means of this distance, which forms a lever arm, and the force effect of the cylinder 3, the necessary moment force is produced to turn the sleeve 17 and further the shaft bar 11 and the part 13. By means of the joint in the frame 2, the cylinder 3 can rotate around a rotation axis which is parallel to the line Z:

The parts 11 , 13 and 17 are supported by each other in the direction of the line Z, and their joint length is fitted to correspond to the distance between the arms 1 a, 1b. The sleeve 17 is placed centrally between the arms 1a, 1 b, and the other parts are placed symmetrically in a corresponding manner. Alternatively, the flanges 11 b and 13a can also be mounted on the outer surfaces of the arms 1a, 1 b, wherein the widths of the parts must be fitted accordingly, or spacers must be placed therebetween. The mounting of the sleeve 17 may also vary, depend- ing on the actuator used. The pitch and more detailed dimensions of the grooving 11e may vary according to the forces to be transmitted and the material used. Between the shaft bar 11 and the parts related thereto, there is one or more cotter joints made to correspond to the grooving 11e.

Furthermore, the invention can be applied within the scope of the appended claims.

Claims

Claims:

1. A link mechanism for a harvester head, the harvester head comprising at least:

a swivelling arm (1), by means of which the frame (2) of the harvester head is arranged to be suspended in the boom assembly of a working machine, and

a link mechanism (10) which is arranged to couple the swivelling arm (1) to the frame (2) and to pivot them in relation to each other around a horizontal axis (Z),

- as well as actuator means (3) for pivoting, to provide a force effective between the frame (2) and the swivelling arm (1),

characterized in that

- the link mechanism (10) comprises a shaft (11 , 13) to be placed on the axis (Z), the frame (2) being coupled to the shaft in a freely rotating manner and the swivelling arm (1) being connected to the frame in a non-rotating manner, and which shaft (11 , 13) is arranged to be rotated by means of actuators (3) in relation to the frame (2) and to transmit a force effect via said shaft (11 , 13) also to the swivelling arm (1) for pivoting.

2. The link mechanism (10) according to claim 1 , characterized in that the shaft (11 , 13) comprises at least:

a shaft bar (11), at whose first end (11a), outermost, are fitted first mounting means (11b) for the swivelling arm (1) and, inner than them, first bearing means (11 d, 12) for the frame (2), and also - a separate part (13) to be slided around the second end

(11c) of the shaft bar (11), corresponding second mounting means (13a) being fitted outermost in the part (13) and second bearing means (13b, 14) more to the inside for the frame (2), wherein means (11 e) are fitted between the part

(13) and the shaft bar (11) to prevent at least their mutual rotational motion.

3. The link mechanism (10) according to claim 2, characterized in that it comprises a sleeve (17) slidable around the middle part of the axle shaft (11), by means of which sleeve (17) the actuators (3) are arrange to rotate the axle shaft (11), wherein means (11e) are fitted between the sleeve (17) and the axle shaft (11) to prevent at least their mutual rotational motion.

4. The link mechanism (10) according to claim 2 or 3, characterized in that the axle shaft (11) comprises an external grooving (11e) which extends from its one end (11c) over at least the central part and which is arranged for the transmission of the rotational motion.

5. The link mechanism (10) according to any of the claims 2 to 4, characterized in that the first and second bearing means (11 d, 12, 13b, 14) for the frame (2) each comprise a bushing (12, 14) rotatable around the axle shaft (11) in a sliding manner.