SE2251299A1 - Rear knives in a harvesting apparatus - Google Patents

Abstract

The invention relates to a harvesting apparatus used for felling, delimbing and sectioning trees (14), which harvesting apparatus is attached so as to be freely suspended at one end of a boom of a base machine that is mobile in a forest, which harvesting apparatus includesfirst delimbing knives in front of a feeding device (16) in the direction of feeding, which are articulated to fold underneath the openingsecond delimbing knives, i.e. rear delimbing knives (2, 3), behind the feeding device (16) in the direction of feeding. The rear delimbing knives (2, 3) according to the invention are configured to fold up against the body (1) and their ends are bevelled (3.1) in such a manner that a tree moving in the opening is guided by means of the bevel (3.1) past the rear delimbing knife (2,3) even if it should collide with the same.

Description

Rear knives in a harvesting apparatus The invention relates to a harvesting apparatus used for felling, delimbing, sectioning, and these days even measuring, trees, in particular a harvesting apparatus as set out in the preamble of claim l. The harvesting apparatus is attached to the end of a boom of a base machine that is mobile in a forest. In general, a harvesting apparatus is, in a manner of speaking, The weight of a harvesting apparatus lies in 5000 kg. freely suspended. a range of 250 - Power consumption is approximately 30 - 200 kW. of 3 - 7 m/s, The feed rate in a delimbing mode lies in a range the delimbing force in a range of 5-40 kN. The invention further relates to a harvesting apparatus in which the feeding of the tree occurs by means of feed rollers or roller feed. Stroke-feed harvesting apparatuses are not cov- ered by the invention since they use several knives and grippers as a result of the periodic feeding motion. A chainsaw, circular saw or a so-called guillotine is used as the cutting device in harvesting apparatuses. A size of the tree can be ø 50 mm - 1000 mm.

Patent FIl0453l discloses the structure of a harvester head which has, in addition to front delimbing knives (first delimb- ing knives), also rear knives (second delimbing knives). Since the rear knives are not always used, it is advantageous to be able to hide them. In conventional harvester heads, the rear knives have been left out when not in use so that they have been vulnerable to damage. The body of a harvester head conse- quently includes indentations in which the tips of the rear knives can be arranged when the latter are not being used.

The rear knives in harvesting apparatuses are located between the feeding members and the cutting device. There can be one or two rear knives. One longer knife is the most common design. Two knives arranged on either side of the tree can naturally be shorter.

A function of the rear knives is to help support the tree being processed. during' the feeding' motion, especially' during the back-and-forth motion that occurs when the cutting point is being optimized. Large trees naturally require support, but so do tall, thin trees.

In many tree species, a large number of branches also occur in the base area of the tree. The size of the trees at this stage is not great; in commercial forestry, it is possible to talk of a maximum diameter of 30 cm. Not all of these branches can be removed with the main delimbing knives arranged in front of the feeding apparatus of the harvesting apparatus. Most of these can be removed with a rear knife or knives.

A further important function of the rear knives or knife would be, where possible, to help in gathering a plurality of trees in the harvesting apparatus. In this case, one is talking about smaller trees, generally with a diameter less than 20 cm. Such articulated rear knives exist; however, mechanical problems limit their usage. These gathering rear knives (or knife) re- quire a large amount of space because of the joints. In use, the knives in operation are also subjected to external forces as they collide with stumps and trees close by. Solutions have been proposed but none have caught on due to problems with them.

While providing the harvesting apparatus with additional tree- processing features, the rear knives (or knife) limit the operation of the apparatus. This is the case when there is a plurality of trees close together. The rear knives take up space during the introduction of the tree into the harvesting apparatus. Trees close by that are left standing are easily damaged through contact with the knives. This problem can be avoided, e.g., by retracting the rear knives into a space in the body of the apparatus (FIlO453l). Such a solution is also known for a single knife (FIl23l55). The large amount of space required by the knife inside the apparatus necessitates the creation of an opening in the body structure. It becomes nec- essary for the body to be interrupted and supported externally. in winter snow accumu- In addition, small branches and, e.g., late in the opening. Probably for these reasons, this solution is not commercially available. With the rear knives according to the invention, the objects of supporting the tree, delimbing the tree, gathering trees and retracting the knives in problematic situations are resolved. The starting point of this solution is the design of the feeding device.

The most common feeding system in harvesting apparatuses cur- rently is based on the presence of three rollers. Two rollers support the tree from below and one roller receives the com- pressive force of the lower rollers via the upper surface of the tree. In these devices, especially with smaller trees, the tree exerts a large pressure on the top roller mechanically. In order for feeding to be successful, the tree must always be pressed against the top roller.

Consequently, if one wants to retract the rear knives in a problematic situation, the rear knives have to be moved all the way up to the top side of the top roller. As a result, a separate retraction space has to be built for the knife or knives (FIlO453l). The harvester head according to the invention provides a new solution with respect to the use of the rear knives with which the load on the passive rear knives is not too high during the feeding of the tree. The characteristic features of the har- vester head according to the invention are indicated in patent claim l. Advantageous embodiments are defined in the dependent claims 2-6.Since the ends of the rear delimbing knives are bevelled in such a manner that the tree moving in the jaws is guided by means of the bevel past the rear delimbing knife even if it should collide with the same, they can be folded against the body.

A feeding system using two rollers or tracks moving in opposite directions is also known. The rollers or tracks are roughly at the sides of the tree; the angular difference between the trac- tive surfaces can be lO°f 5°. In these harvesting apparatuses, the support of the tree is based on the vertical force produced by the main delimbing knives and the load-bearing force can of course be increased by using the rear knives. Prior to felling, especially in confined spaces, no effort is made to position the tree against the body of the machine. The feeding of the tree will succeed even if the tree is, e.g., 30 mm f lO mm away from the body of the apparatus. After all, the total width of a tractive surface is lOO-300 mm. The rear knives according to the invention are thus configured utilizing the features of the two feeding devices operating in opposite directions in the harvesting apparatus.

A low compressive pressure of the tree against the body of the apparatus is essential with the above-mentioned feeding device.

The rear knives can now be moved up against the body prior to N B the tree being drawn against the rear knives. Preferably, the rear knives can be arranged against the frame while taking up approximately 30 mm of space in the direction of the tractive surface of the roller or track. the invention is described by means of ex- which In the following, amples and with reference to the accompanying figures, illustrate a harvester head according to the invention in a harvester.

Figure l shows the harvesting apparatus viewed from the side of the cutting device Figure 2 shows the harvesting apparatus illustrated from the side of the saw housing Figure 3 shows a situation where a tree is fed to the front side of the rear knives Figure 4 shows the harvesting apparatus processing a medium- sized tree Figure 5 shows the harvesting apparatus with the rear knives in an open position Figure 6 shows the release of the rear knives as their auxil- iary arm rotates outwards The harvesting apparatus according to the invention is illus- trated in Figure l in a side view of the cutting device. The sectional figure shows the body l and rear knives of the appa- ratus.

The rear knives consist of the parts 2 and 3. The part 2 (the auxiliary arm) is attached by a pin 7 to the body l in the direction of travel of the tree. The rear knife further includes the part 3, which is attached by a pin 6 to the part 2. A cylinder 4 is fixed in the body l by a pin 9. The cylinder 4 is attached to the part 2 by a pin 8. A spring ll holds the part 3 against a support piece lO via the pin 6. A support 6 roller 12 is also visible in Figure 1. The lower surface 13 of this support roller 12 is normally approximately 6 mm away from the bottom 5 of the body 1. This is in order to avoid that the tree wears the surface to an excessive degree during its move- ment. The parts 3 are arranged so as not to collide with one another when rotated by the cylinder 4.

Figure 2 illustrates the harvesting apparatus in a side illus- tration of the saw housing 15. A tree to be processed 14 is arranged between feed rollers 16. The tree 14 in Figure 2 is medium-sized on the scale of the body 1, yet still represents a problematically large tree. The tree 14 can be fed when the part 3 of the rear knives lies up against the lower surface 5 of the body 1. The distance between the main delimbing knives and the rear knives, i.e. the parts 2 and 3, is approximately 60 cm f 20 cm. When the part 3 lies between a point 5 and the tree 14 as it does here, the direction of travel of the tree 14 only changes by 1° f 1°. It is assumed here that the lower surface 13 of the support wheel 12 is approximately 6 mm away from the lower surface 5 of the body 1. The knife, i.e. the part 3, is about 15 mm thick. A cutting bar nose 17 is visible through the sectioned saw housing 15.

Figure 3 shows a situation in which the tree is fed to the front side of the rear knives. Such a situation arises when, after the felling of the tree, the main delimbing knives en- counter oversized branches. The tree 14, moving past the rear knives 3, is reversed in the direction of the feeding devices. A bevel 3.1 forces the colliding tree to pass the rear knives. When now being fed forward, the tree 14 does not collide with the knives 3 because the part 3 includes a sharp portion for delimbing. When fed in the forward direction, the top corner 18 of the tree 14 passes under the knives 3 due to the sharpened 7 bevel of the part 3 (the arrangement of the knives 3 in relation to each other is visible in the figure). In Figure 4, a medium-sized tree 14 is arranged in the harvest- ing apparatus. The rear knives (the parts 2 and 3) now support roughly the lower surface of the tree 14. The parts 2 and 3 are dimensioned in relation to the body 1 via the pins 7 in such a manner that an active contact of the part 3 with the tree 14 occurs at the tip 3.1 of the part 3 along approximately half the distance between the tip 3.1 and the pin 6. Consequently, only one part of the rear knife needs to have a cutting part, likewise along only half of its length.

Figure 5 shows the harvesting apparatus with the rear knives (the parts 2 and 3) in an open position. Figure 6 shows the operation of the rear knives and 3) (the parts 2 when the rear knives are opened while gathering trees, a first tree being shown in the tree-harvesting apparatus in the figure. The operation of the knives 2 and 3 is quite common and known in itself. However, as shown in Figure 1, both knives (the parts 2 and 3) have their own cylinder. This solution saves space in a longitudinal direction in the harvesting ap- paratus. A support wheel 12 can be arranged in the area of the knives 2 and 3. This reduces the friction acting on the lower surface. If the wheel 12 is omitted, the cylinders 4 can be replaced by a single cylinder using pins 8. Still in Figure 6, when the cylinder 4 rotates (not illustrated) the part 2 in the direction of the arrow, buckles. the spring 11 (or equivalent) When the tree 14 is in the grasp of the feeding members, the knives (the parts 2 and 3) are released, the cylinder 4 continuing the motion until the situation il- lustrated in Figure 5 is reached.

The width of the feeding roller/track is 15 - 80%, most pref- erably 16 - 40%, of its maximum holding width. If the wheel 12 is omitted, the cylinders 4 can be replaced by a single cylinder using pins 8.

Still in Figure 6, when the cylinder 4 rotates (not illustrated) the part 2 in the direction of the arrow, buckles. the spring 11 (or equivalent) When the tree 14 is in the grasp of the feeding members, the knives (the parts 2 and 3) are released, the cylinder 4 continuing the motion until the situation il- lustrated in Figure 5 is reached.

If the nominal size of the tree is 300 mm, the width dimension is 120 mm - 400 mm, preferably 150 - 300 mm.

Most preferably, the opposite feeding rollers/tracks 16 form support surfaces on opposite sides of the tree of nominal size, which support surfaces deviate by 0 - 8 degrees, most preferably by 0 - 5 degrees, from the vertical so that at an extreme deviation the feeding rollers/tracks 16 lift the tree to be processed upwards. The nominal size is often 50-70%, 60%, e.g. of the maximum grip. If the maximum diameter is 500 mm, the nominal size with which the harvesting apparatus works best is 300 mm. The small deviation mentioned above makes it possible for said nominal size to fit inside the small minimum diameter of the opening.

Claims (6)

1. A harvesting apparatus used for felling, delimbing and sectioning trees (14), which harvesting apparatus is attached so as to be freely suspended at one end of a boom of a base machine that is mobile in a forest, which harvesting apparatus includes 0 a body (1) that is supportable at the end of said boom, 0 a feeding device (16) for conveying a tree (14) through an opening from the front towards the back, 0 first delimbing knives, i.e. front delimbing knives in front of the feeding device (16) in the direction of feed- ing, which are articulated to fold underneath the opening, rear delimbing knives (2, (16) 0 second delimbing knives, i.e. 3) behind the feeding device in the direction of feeding and wherein the opening is formed in the delimbing position by (1), (16), 0 a lower surface (5) of the body 0 two opposite feed rollers/tracks 0 the opposite first delimbing knives pressed against the underside of the tree to be processed, and 0 the opposite rear knives (2, 3) pressed against the un- derside of the tree to be processed if they are in use, characterized in that the rear delimbing knives (2, 3) are configured to fold up against the body (1) and their ends are bevelled (3.1) in such a manner that the tree moving in the opening is guided by means of the bevel (3.1) past the rear delimbing knife (2, 3) even if it should collide with the same.

2. The harvesting apparatus according to claim 1, char- include the two opposite which acterized i11 that feeding' devices feeding rollers/tracks (16) as the only feeding members, are arranged with a precision of f10° in a circumferential direction.

3. The harvesting apparatus according to claim 1 or 2, characterized in that the rear delimbing knives (2, 3) consist of two parts comprising a base part (2) and (3.l) and a tip part (3) the tips (1). of the tip parts (3) bend away from the body

4. The harvesting apparatus according to any of claims 1 _ 3, is 15 - characterized in that a width of the feeding roller/track 80%, most preferably 16 - 40 %, of its maximum holding width.

5. The harvesting apparatus according to any of claims 1 - 4, characterized in that a lower surface (5) of the body (1) has a support roller (12) which reduces the friction acting on the lower surface (5).

6. The harvesting apparatus according to any of claims 1 _ 5, (16) characterized in that the opposite feeding rollers/tracks form support surfaces on opposite sides of a tree (14) of a nominal size, which support surfaces deviate by O - 8 degrees, from the vertical so that at an (16) most preferably O - 5 degrees, extreme deviation the feeding rollers/tracks lift the tree (14) to be processed upwards.