CA2933804A1

CA2933804A1 - Delimbing blade

Info

Publication number: CA2933804A1
Application number: CA2933804A
Authority: CA
Inventors: Tero Kaatrasalo; Jouni Viitikka
Original assignee: Ponsse Oyj
Current assignee: Ponsse Oyj
Priority date: 2015-06-23
Filing date: 2016-06-21
Publication date: 2016-12-23
Anticipated expiration: 2036-06-21
Also published as: CA2933804C; FI129895B; FI20155486A

Abstract

The present invention relates to a delimbing blade (4) for use in a harvester head (1) of a forest machine, in particular. Such a delimbing blade comprises a base part (6) to rotatably fix the delimbing blade to the harvester head, and a blade part (8) to process tree trunks (16) handled in the harvester head. This blade part is curved in shape and at least partly surrounds the trunk being handled in the harvester head, whereby the radius of curvature (r) of the blade is positioned on the side of the trunk being handled. The blade part (8) comprises at its end opposite the base part (6), on the side of the radius of curvature on its inner surface (13), at least one gripping member (14). This gripping member is formed on an outer tip (12) opposite the base part of the blade part (8), and comprises a substantially sharp gripping tip (15) which bites firmly on the tree trunk (16) being handled.

Description

DELIMBING BLADE
Background of the invention [0001] The present invention relates to a delimbing blade. In particular, such a delimbing blade is used in a feeding, delimbing, and cutting harvester head of a forest machine, known per se.

[0002] In harvesting, wood may be handled in numerous methods. A
conventional way is to cut and handle a tree at one work stage with a harvester head of a work machine moving in a forest. Another way is to carry out just the cutting of a tree with said work machine, after which the trunk of a tree is processed at a second work stage and advantageously with another work machine.

[0003] In such a second work method, it must be possible to grip the trunk of a tree, and is must be lifted off the ground, advantageously with a harvester head handling the trunk. In such a disclosed method of operation, problems often arise when the attempt is made to lift the trunk off the ground or from a pile due to the fact that the harvester head of the conventional, so-called single grip harvester is as a general rule not originally designed for this purpose. If a trunk is heavy or slippery, it is difficult to achieve a proper grip on it to perform a secure and smooth lifting operation. In order to try to solve the problem, the pressing force of the delimbing blades acting as the gripping member has been increased. However, this detrimentally adds to the total weight of the harvester head and unnecessarily strains its structures, and an adequately secure grip is not achieved, anyway.
Summary of the invention

[0004] The invention was developed to address the prior art drawbacks.

[0005] Accordingly, there is described a delimbing blade for use in at least a feeding, delimbing, and cutting harvester head of a forest machine, such a delimbing blade comprising: a base part for rotatably connecting a delimbing blade to the harvester head, and a blade part for processing tree trunks handled in the harvester head, whereby the blade part is arranged to be curved in shape and to at least partly surround the tree trunk being handled in the harvester head, the radius of curvature of the blade part being on the side of the tree trunk being handled, ch a r a cte rized in that the blade part further comprises, at the end opposite its base part, at least one gripping member on the inner surface on the side of its radius of curvature, so that the gripping member is formed on the outer tip end opposite the base part of the blade part, said gripping member comprising a substantially sharp gripping tip which bites firmly on the tree trunk being handled.
[0007] The invention is based on the realization that a more efficient way than the pressing force is to increase the friction between the delimbing blades and the trunk of the tree, even to achieve a device that could grip the trunk that otherwise easily slips out of the grip of the harvester head.
[0008] Within the scope of the present invention, a "forest machine" will refer to both a tree-cutting and handling work machine and a stationary work and processing machine handling trees already cut down.
[0009] The term "harvester head" in this context is used in the wide sense, including in it felling, feeding, delimbing, and cutting devices in mobile work machines, and devices in mobile or stationary work machines, which lift, feed, delimb, or cut tree trunks.
[0010] The terms "up", "down", "above" and so forth used in the specification illustrate the features of the invention in directions that are relative to the delimbing blade of the invention as it is presented in the attached figures.
[0011] Embodiments of the invention provide considerable advantages.
Therefore the delimbing blade according to the invention, in a simple and reliable way, allows for the lifting of a heavy, icy, or otherwise slippery trunk. This way the processing work carried out by a harvester head becomes substantially easier and more efficient.
[0012] The gripping members on the delimbing blades make it possible to move a trunk by just pinching by the tip part of the delimbing blade.
Consequently, the task of moving tree trunks becomes considerably faster as lifting them entirely to the inside of the harvester head may be avoided.
[0013] In particular, embodiments of the invention are advantageous in the handling of large-diameter tree trunks. A conventional delimbing blade, due to its geometry, is not very well capable of supporting such trunks. When a small-diameter trunk is gripped, the inner surfaces of a pair of blades settling against the trunk will establish an opening angle against gravity, as the trunk rests against the pair of blades. When the tree trunk has a large diameter, the inner surfaces of the pair of blades settling against the trunk will, however, be parallel or even establish an opening angle in the direction of gravity. Without the grip provided by the present invention, these trunks can no longer be lifted or moved about, because the trunk tends to slip out of the delimbing blades. With conventional delimbing blades, a trunk that is too heavy tries to open the delimbing blades, but in the present solution, the gripping members prevent it from falling off. LLarge trunks may also be moved by using a lower pressing force, whereby the strain on the coupling pins and bearings in the frame structure of the cutting head, for example, will be lesser than before.
[0014] Such a delimbing blade according to the invention easily replaces the blades now in use, with all the other structural and usage features remaining substantially unchanged.
[0015] By making the gripping member of a delimbing blade removable, it may be quickly sharpened of replaced with a new one under any operating circumstances.
[0016] Other advantages provided by the embodiments of the invention are disclosed in the following more detailed description of specific embodiments of the invention.
Brief description of the figures [0017] In the following, a preferred embodiment of the invention will be explained in more detail with reference to the accompanying drawing, in which [0018] Figure 1 shows an exemplary harvester head provided with a delimbing blade, [0019] Figure 2 is an axonometric view of a delimbing blade as seen obliquely from above, [0020] Figure 3 shows a longitudinal cross-section of delimbing blade, [0021] Figure 4 shows a cross-section detail of an embodiment of a gripping member at the end of a delimbing blade, [0022] Figure 5 shows a cross-section detail of a second embodiment of a gripping member at the end of a delimbing blade, [0023] Figure 6 shows a cross-section detail of a third embodiment of a gripping member at the end of a delimbing blade, [0024] Figure 7 shows a cross-section detail of a fourth embodiment of a gripping member at the end of a delimbing blade, [0025] Figure 8 shows a cross-section detail of a fifth embodiment of a gripping member at the end of a delimbing blade, [0026] Figure 9 shows a tree trunk supported by delimbing blades and gripping members therein.
Detailed description of the preferred embodiment [0027] The present figures do not show the delimbing blade in scale but the figures are schematic, illustrating the structure and operation of the preferred embodiments in principle. The structural parts shown by reference numbers in the attached figures then correspond to the structural parts marked by reference numbers in this specification.
[0028] In cutting down and handling a tree, or in its handling only, use is made of different cutting or processing heads 1 that are known per se as regard their structure. One of these is shown in Figure 1. Such a harvester head comprises a frame into which are adapted, advantageously but not necessarily, feeding rollers 2 that feed the trunk, upper blades 3 that cut off branches from the tree, and delimbing blades 4 that may be rotated towards the tree. Finally, the cutting head has a cutter 5 by means of which the one or more trunks on it may be cut where desired. Such a cutting head is not, however, the object of the disclosed solution and therefore will not be described here in any greater detail.
[0029] There are two or more delimbing blades 4 in the cutting head, and they are conventionally arranged pairwise on the cutting head in opposite position.
In addition to cutting off branches, the delimbing blades also have the task of gripping the trunk being handled and keeping it in the cutting head 1 during the handling. To improve delimbing and gripping, such delimbing blades are usually formed to be mainly curved, so that they expand hyperbolically, for example. A

delimbing blade is usually made of welding from a steel plate. Alternatively, it may also be made solid or hollow by casting. When such delimbing blades installed substantially opposite each other in the cutting head are rotated towards each other, a space will be formed at the cutting head, which holds the tree in the cutting head and is mainly surrounded by blades of different kind.
[0030] Such a delimbing head 4 comprises in accordance with Figures 2 and 3, for example, a base part 6 for rotatably connecting a delimbing blade to the harvester head 1 by means of a pivot 7 in the base part. The delimbing blade further comprises a blade part 8 to process the tree trunks in the harvester head. In such a case, the blade part, at least, is arranged to have a curved shape, whereby the radius of curvature r of the blade part will be on the side of the trunk being processed in the cutting head. Because the delimbing blades have at least one edge sharpened to be a cutting blade 9 and 10, it is possible to remove branches off the trunk by moving the trunk in the cutting head along its longitudinal axis.
To enhance working, it is advantageous to provide both the edges of a delimbing blade which make contact with a trunk with a sharpening as shown in Figure 2.
[0031] For picking up trunks from the ground or a pile of trunks, it is advantageous to shape the arc of the delimbing blade 4 to have a larger radius of curvature r at the portion that is opposite the base part 6. By gradually changing the radius of curvature, a blade part 8 opening hyperbolically, for example, is achieved.
In this manner, the part on the outer tip 12 in the delimbing blade will be straighter as regards its longitudinal section than the base end, or even entirely straight. A
delimbing blade that straightens out this way may be more easily guided between trunks in a pile or lying on the ground next to each other, for example. With this purpose in mind, it is further advantageous to make the outer tip 12 of a delimbing blade blunt. A blunt outer tip of this kind will not harm surrounding trees to the extent a cutting and sharp outer tip might, and at the same time a blunt outer tip will not stick to a trunk it encounters. A shape for the delimbing blade is thus achieved, which easily pushes its way to between trees, and a single trunk or a plurality of trunks may be selected and picked up to the harvester head 1 with ease.
[0032] The blade part 8 of the presented delimbing blade 4 further comprises at its outer tip 12, opposite the blade part 6, at least one gripping

6 member 14 on the inner surface 13 on the side of the radius of curvature r.
Such a gripping member comprises a gripping tip 15, substantially sharp and shaped to bite firmly on the surface of the trunk being handled, and adapted to extend to the inside of the plane surface defined by the inner surface of the delimbing blade. With such a gripping member, it is made sure that a trunk 16 cannot slide out of the grip of the harvester head 1 as the trunk is picked up as shown in Figure 9. Due to the shaping of the gripping members and gripping tips, when a trunk is being lifted, its own weight may even be utilized. Gravity forces the trunk against the gripping tips which sink into or penetrate the trunk running off downward, from the inner surface of the delimbing blades. So, the gripping tips lock the trunk to the cutting head due to the grip between the trunk and the gripping member. The gripping members may be shaped differently for different tree species or conditions. Therefore, their width, direction of protrusion, or length may be modified to suit different uses.
[0033] It is advantageous to arrange gripping members 14 on opposite delimbing blades 4, whereby gripping tips 15 on the opposite gripping members may be adapted to protrude towards each other. However, the direction of the gripping tip on the gripping member may vary, even being parallel to the inner surface 13 of the blade part 8 in one preferred embodiment (cf. Figure 5). At its largest, the direction of the gripping tip may be in the direction of the radius of curvature r of the blade part 8.
[0034] The outer tip 12 according to Figures 4 and 5 on the delimbing blade 4 advantageously comprises a cylindrical element substantially perpendicular to the longitudinal axis of the delimbing blade. To form a gripping member of the type described in the above, a part has been cut off from such a cylindrical outer tip on the side of the inner surface 13 of the radius of curvature r of the delimbing blade. As shown in Figure 4, such a cut part comprises a piece substantially of the shape of a circular sector. In this preferred embodiment, the other side of this circular sector is also essentially coinciding with the inner surface of the blade part.
The central angle a of the circular sector may vary between 15 and 90 degrees.
[0035] In the embodiment according to Figure 5, the gripping member is in turn formed by cutting off an elliptical part from the cylindrical element which is substantially perpendicular to the longitudinal axis of the delimbing blade.
In the present preferred embodiment, this comprises a part substantially a circular

7 segment in shape. In this preferred embodiment, the tangent of the first outer corner of this circular segment, lower in the figure, is substantially coinciding with the inner surface of the blade part, and the tangent of the opposite, second outer corner, which is higher, is substantially parallel to the first tangent. The gripping tip of a gripping member formed this way is also substantially directed parallel to the inner surface of the blade part.
[0036] To improve maintainability, it is advantageous to arrange the gripping member 14 detachably in the delimbing blade 4. In such a case, the gripping member comprises, for example, a means detachably connected to the blade part 8 by a mechanical grip, such as a screw coupling 17, cf. Figure 6.
It is further possible to arrange the gripping member in the blade part by a form-blocked joint, known per se. A gripping member that may be detached like this is easily replaceable by a new one, or disconnected for sharpening.
[0037] The present gripping member 14 may also be arranged at the outer tip 8 of the delimbing blade 8 to turn in relation to the inner surface 13.
Embodiments of this type are shown in Figure 7 and 8. The figures show that an indentation 19 has been arranged in the outer tip, into which the gripping member, elongated as to its cross-section, may be guided to be substantially parallel to the longitudinal axis of the delimbing blade. The first end of such a gripping member has a joint means to couple it to the blade part. This joint means comprises, for example, an axle (not shown) which is transverse in relation to the longitudinal axis of the delimbing blade, which may be detachably arranged in a channel 20 shown in the figures. At the other end of the gripping member, opposite the joint means, there is the gripping tip 15 formed by a bevel to establish grip on the tree.
[0038] The gripping member 14 shown by Figure 7 may be controlled by a spring element (not shown). A gripping tip 15 of such a gripping member continuously protrudes clearly from the inner surface of the delimbing blade, so that the bevelled end forming the gripping tip could be guided to a position protruding from the inner surface 13 of the blade part 8. This way, the gripping tip is at all times ready to adhere to a trunk which is about to become loose of the grip of the cutting head 1 and sliding downward in it. When a trunk in a pile of trunks or on the ground is gripped, the gripping member in turn is pressed into the indentation as a result of the pressure the trunk puts on it. The damaging of the gripping member is

8 minimized due its yielding. The spring element controlling the gripping member may be a coil spring as well as another resilient means for the purpose.
[0039] The gripping member 14 may also be adapted in the indentation 19 without the spring means described in the above. The gripping tip 15 of such a gripping member rotates out of the indentation as a result of gravity when the delimbing blade is substantially vertical and the outer tip 12 is the lowest.
[0040] A person skilled in the art will find it obvious that, as technology advances, the basic idea of the invention may be implemented in many different ways. The invention and its embodiments are thus not restricted to the above examples but may vary within the scope of the claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A delimbing blade for use in at least a feeding, delimbing, and cutting harvester head of a forest machine, such a delimbing blade comprising:
a base part for rotatably connecting a delimbing blade to the harvester head, and a blade part for processing tree trunks handled in the harvester head, whereby the blade part is arranged to be curved in shape and to at least partly surround the tree trunk being handled in the harvester head, the radius of curvature of the blade part being on the side of the tree trunk being handled, characterized in that the blade part further comprises, at the end opposite its base part, at least one gripping member on the inner surface on the side of its radius of curvature, so that the gripping member is formed on the outer tip end opposite the base part of the blade part, said gripping member comprising a substantially sharp gripping tip which bites firmly on the tree trunk being handled.

2. The delimbing blade as claimed in claim 1, characterized in that the outer tip forms a substantially blunt end directed towards the tree trunk intended to be gripped by the blade part.

3. The delimbing blade as claimed in claim 1, characterized in that the outer tip comprises a cylindrical element substantially perpendicular to the longitudinal axis of the delimbing blade, whereby to form said at least one gripping member, a part has been cut off from the side of the cylindrical outer tip on the inner surface of the radius of curvature on the base part side.

4. The delimbing blade as claimed in claim 3, characterized in that said cut part comprises a circular sector.

5. The delimbing blade as claimed in claim 4, characterized in that the other side of the circular sector is substantially coinciding with the inner surface of the blade part.

6. The delimbing blade as claimed in claim 5, characterized in that the central angle of the circular sector is 15 to 90 degrees.

7. The delimbing blade as claimed in any one of claims 1 to 6, characterized in that the gripping member comprises a member detachably mounted on the blade part.

8. The delimbing blade as claimed in claim 7, characterized in that the gripping member is arranged on the blade part with a screw joint.

9. The delimbing blade as claimed in claim 7, characterized in that the gripping member is arranged on the blade part with a form-blocked joint.

10. The delimbing blade as claimed in any one of claims 1 to 9, characterized in that the gripping member comprises a gripping tip arranged to turn in relation to the inner surface of the blade part.

11. The delimbing blade as claimed in claim 10, characterized in that the gripping tip comprises a longitudinal member, whereby a first end of the member has a pivot means to connect it to the blade part, and the second end, which is opposite the pivot means, is bevelled to establish a grip on a tree.

12. The delimbing blade as claimed in claim 11, characterized in that the gripping tip is flexibly arranged on the blade part in order to direct the bevelled end to a position protruding from the inner surface of the blade part.

13. The delimbing blade as claimed in claim 11, characterized in that the gripping tip is arranged to be controlled by gravity, so that the bevelled end of the gripping tip pivoted on the blade part sets itself to a position protruding from the inner surface of the blade part while the outer tip of the blade part (8) is aligned in a substantially vertical position downward.