HARVESTER HEAD AND METHOD FOR CONTROLLING DEBARKING PROPERTIES IN HARVESTER HEAD

HARVESTER HEAD AND METHOD FOR CONTROLLING DEBARKING PROPERTIES IN HARVESTER HEAD

TECHNICAL FIELD OF THE INVENTION

The invention relates to a harvester head and a method for controlling debarking properties in a harvester head according to the preambles of the independent claims presented further below. The invention especially relates to a new manner of realizing debarking knives in a harvester head or a corresponding tree processing device.

PRIOR ART

Typically a harvester head or the equivalent contains one or more pairs of debarking knives or blades. Generally the harvester head has front knives or upper blades and often also rear knives, i.e. lower blades. The knives of the same knife pair, which knives have been placed on separate sides of a tree to be processed, i.e. the left and right knife, are often shaped identically to each other, but as mirror images.

Typically the knives can be moved hydraulically in relation to the frame of the device, away from and towards the travel route of the tree being processed in the device, i.e. the tree processing route of the harvester head. The harvester head may also have fixed debarking knives, i.e. debarking knives that are immobile in relation to the frame. Typically there are knives at least on both sides of the tree to be processed. The turnable knives can be made to open, i.e. turn away from the tree processing route, in order to enable the grabbing of the tree. During the processing, i.e. feeding, of the tree, the knives are pushed closed, i.e. they are turned toward the tree processing route, i.e. into contact with the tree to be processed. When debarking a tree, the knives can thus be made to hug the tree in a way, i.e. their movement can be made to follow the narrowing and expanding of the tree, i.e. the shape of the surface of the tree. In addition to the debarking, the knives can also be used for grabbing trees and for picking trees as well as for delimbing trees. The knives are usually sharpened at their so-called front side, i.e. on the side, which processes the tree being moved forward in the harvester head, to be sharper or more grasping than at their rear side. Usually debarking can be performed with the knives also when feeding a tree backwards, but typically the rear side of the knife does not need to be as sharp or as grasping as the front side. Thus a separate left and right knife or blade is needed.

Several different blades and knives usually have to be manufactured for different purposes. The blades need to be changed for example when a blade has broken. The blades may need to be changed also when the processing target, i.e. the wood species, is changed to another. The blades may need to be changed also when the processing need changes, i.e. for example debarking blades can be changed into delimbing blades or delimbing blades can be changed into debarking blades. Because the changing of blades according to need is laborious or even impossible, the debarking often has to be performed with a blade, which is poorly suited for the purpose.

OBJECT AND BRIEF DESCRIPTION OF THE INVENTION

It is an object of the present invention to reduce or even eliminate the above- mentioned problems appearing in prior art.

It is especially an object of the present invention to facilitate the changing of debarking members in a harvester head. It is especially an object of the present invention to reduce the need for different debarking members.

It is especially an object of the present invention to provide an even more efficient manner of controlling the debarking properties of a harvester head.

In order to achieve among others the objects mentioned above, the harvester head and the method and other objects of the invention are characterized by what is presented in the characterizing parts of the enclosed independent claims. The embodiment examples and advantages mentioned in this text relate, where applicable, to both the harvester head and the method according to the invention, even if this is not always specifically mentioned.

In this text harvester head means tree processing devices connectable to a base machine which processes tree trunks, such as a harvester head, a delimbing device, a debarking device, a tree collecting device, an energy wood harvester, a felling head. A connecting means has typically been attached to the frame of the harvester head, via which connecting means the harvester head is connectable to a base machine that uses it, such as a base machine made especially for use with a harvester, which base machine generally travels either on wheels or on tracks. Other possible base machines are for example a wheel loader, an excavator or another excavating machine, a tractor, a truck or another mobile device.

A typical harvester head comprises a frame and tree processing members attached to the frame. The tree processing members define, with their structure and function, a longitudinal tree processing route of the harvester head, where the tree trunks mainly are during the processing. The tree processing members can for example be tree support rollers or other tree support members, tree feeding rollers, delimbing devices, debarking devices. The structure and operation of some tree processing members do not as such require a certain direction from the tree to be processed. Such members are for example some blades or measuring devices, which measure the tree.

In a typical harvester head according to the invention at least one of the tree processing members is a debarking member, which consists of at least two parts, i.e. a base part and a knife part. The base part is attached to the frame of the harvester head. The knife part is meant to debark the tree trunk on the tree processing route. The base part and the knife part are attached together with a detachable attachment. The detachable attachment can for example be a flange attachment, which is easy to arrange to be stable and quick to open and attach. The detachable attachment can also for example be a male-female type attachment or a dovetail attachment or some other attachment comprising attaching members, which are placed to overlap or inside each other. Screws, bolts, nuts, latches, cotters, locking pins or other locking means, which can be opened, can be used in the detachable attachment.

In a typical method according to the invention for controlling debarking properties, a harvester head is used, which has a debarking member. The debarking member has a base part attached to the frame of the harvester head and a knife part attached detachably thereto. The method comprises

- opening the attachment between the base part and the knife part,

- detaching the knife part from the base part,

- attaching a new knife part to the base part.

In an embodiment of the invention the harvester head has two or more debarking members according to the invention. Thus the detachable attachments are congruent, so that the knife parts can be changed between different base parts. Such a harvester head is used in a method, which comprises

- opening two or more attachments between a base part and a knife part,

- detaching two or more knife parts from the base parts,

- changing at least one detached knife part onto another base part of the same harvester head.

In an embodiment of the invention the knife parts of the two or more debarking members of the harvester head are mainly alike, even identical. In an embodiment of the invention the knife parts of the two debarking members arranged on separate sides of the tree processing route are mainly alike, even identical.

One of the greatest advantages of the invention is that the quality of the debarking improves when the debarking knife can, if necessary, easily be changed to one of a suitable size or shape. The profile of the knife determines how the knife touches, i.e. tangents, the surface of the tree at different tree diameters. One of the greatest advantages of the invention is that it facilitates the changing of the debarking member. Different knife pairs can easily be installed in the harvester head according to need. In an embodiment of the invention the harvester head comprises at least one delimbing member, which is arranged to structurally correspond to debarking members according to the invention. Such a delimbing member thus consists of at least two parts, i.e. a base part and a knife part. In some cases it may be possible that debarking knives can be used as delimbing knives and vice versa. In these cases debarking knives of a larger-size harvester head can be used as delimbing knives of a smaller harvester head. On the other hand delimbing knives of a smaller-size harvester head can thus be used as debarking knives of a larger harvester head. Due to the invention, a front knife of a larger harvester head can for example easily be fitted as a rear knife of a smaller model and even the other way around. The trees to be debarked are usually smaller in diameter than trees to be delimbed with the same knives.

One of the greatest advantages of the invention is that with its aid, the same knife part can be installed either on the right or the left side of the harvester head. Thus costs and effort is saved, for example the production series can be larger and the need for spare parts is reduced and the service is simplified.

One of the greatest advantages of the invention is that when the knife parts are congruent in their shape, also the debarking result, i.e. the quality, is congruent on both sides of the tree.

One of the greatest advantages of the invention is that in a situation, where the diameter of the tree is measured based on the position of the debarking member, the measuring precision improves when the knife parts are congruent in their shape.

In an embodiment of the invention the base part of the debarking member is arranged to be moveable in relation to the frame and the harvester head comprises power means for moving the base part and the knife part attached thereto in relation to the frame. The base part can for example be tumable or moveable in a linear manner in relation to the frame of the harvester head. In an embodiment of the invention the base part of the debarking member is arranged to be turnable in relation to the frame so that the knife part is, if desired, moveable toward the tree processing route and away from the tree processing route. The turning angle of the debarking member can for example be about 90 degrees. Such a base part is typically pivoted to the frame of the harvester head. The pivoting can be made durably, because the base part does not need to be detached from the frame during normal use. Typically such a harvester head comprises power means connected between the frame and the debarking member, such as a hydraulic cylinder, for turning the debarking member. In an embodiment of the invention the tree processing members comprise at least

- a first turnable debarking member, which is turnably arranged to the frame on the first side of the tree processing route, and

- a second turnable debarking member, which is turnably arranged to the frame on the second side of the tree processing route.

In this embodiment both the first and the second turnable debarking member comprises a base part, a knife part and a detachable attachment between them. In such a harvester head the first and the second, i.e. the left and the right, knife part can be made the same, even identical. In an embodiment of the invention the first and the second turnable debarking member are arranged as a pair, mainly opposite each other on separate sides of the tree processing route. The knife parts of the same pair are typically arranged to turn to slightly overlap each other. The debarking members of the same pair can be controlled with one or more power members, such as a hydraulic cylinder. The power members controlling the debarking members of the same pair, such as the hydraulic cylinders or the like, can be in the same or different hydraulic fluid circuits. In an embodiment of the invention the pressing force directed by the debarking members onto the surface of the tree, i.e. the pressure level of the power means, such as the hydraulic cylinder, is adjustable according to the diameter of the tree to be processed. In an embodiment the pressure level of the power members is controlled as a proportional function of the diameter of the tree, so that a smaller tree diameter requires a lower pressure. In an embodiment the pressure level of the power members is controlled automatically with the aid of a controlling device, i.e. a computer. The invention is very well suited for debarking hardwood, such as eucalyptus, acacia and mixed hardwood.

BRIEF DESCRIPTION OF THE FIGURES

The invention is described in more detail below with reference to the enclosed schematic drawing, in which

Figure 1 shows a harvester head according to the invention,

Figure 2 shows a debarking member of the invention, and

Figure 3 shows a debarking member pair according to the invention as an exploded view, seen in the longitudinal direction of the harvester head.

DETAILED DESCRIPTION OF THE EXAMPLES OF THE FIGURES

Figure 1 shows a harvester head 1 according to the invention. A tilt arm 3 is tumably attached to the frame 2 of the harvester head. In the middle of the tilt arm 3 there is a rotator 4 and necessary parts 5 for connecting the harvester head to a base machine, such as a forest tractor. Tree processing members have been attached to the frame 2, such as front i.e. upper knives 11 , feeding rollers 6, a cutting saw 7 (shown with dotted lines), and a lower i.e. rear knife 9 (shown with dotted lines). The tree processing members define the tree processing track of the harvester head, on which track there is in the situation in Figure 1 a tree trunk 10 being processed. For the purpose of clarity, only one lower knife 9 is drawn in the figure, but there may be also another lower knife as its pair, on the opposite side of the tree processing track. There may be also other tree processing members in the harvester head, such as moveable gathering paws. The front knife 11 according to the invention, seen better in Figure 2, consists of a base part 13 attached via an axis 12 to the frame and of a knife part 16 attached with a flange attachment to the base part with the aid of bolts 14 and nuts 15. The bolt 14 and nut 15 is drawn schematically only at two bolt openings 24. The curved work surface 17 of the knife part 16 is meant to be in contact with the tree 10 to be processed.

A knife pair is seen in Figure 3, which knife pair consists of a left knife 11 and a right knife 11 '. The left and right knife part 16 and 16' are shaped identically and thus their places can freely be changed, if desired. The changeability is important e.g. when manufacturing cast metal knife parts. Thus the size of the production series is a significant factor in view of the costs. It is possible that the left and right knife part are manufactured, for example by casting, first as alike preforms, but with machining the left and right knife part are created from the alike preforms. This can be done for example by sharpening the work surface of the knife part at its front edge 18 to be so-called more grasping and a relieving is done at the rear edge 19 of the knife.

Not all things needed by the harvester head, such as hydraulic tubes and electric wires, which are known to those skilled in the art, are shown in the embodiments in the figures. The figures show only some preferred embodiment examples according to the invention. The operation of the harvester head is known to those skilled in the art, and it is not further described in this text. It is obvious to someone skilled in the art that the invention is not limited merely to the above- described examples, but the invention may vary within the scope of the claims presented below. The dependent claims present some possible embodiments of the invention, and they are not to be considered to restrict the scope of protection of the invention as such.