An invention related to method and apparatus for converting trees into wood chips standing on their stubs. The apparatus contains a chipping vehicle, at the mobile boom head of which a cutting and chipping unit is installed for cutting trees and converting them into chips. Produced chip is shifted over from chipping unit into a chip container on the vehicle.

Today, in harvesting small-sized timber in connection with improvement cuttings from growing stands, some of the trees must be thinned out in the age of ab 20-30 years, in order to make place for the tops of remaining trees and to avoid pole-stage of forest. Felling has been carried out mainly by timber workers who fell, delimbe and cut the trees to be thinned out into 3 meter blocks which are then collected into piles along driving tracks and transported to timber yards e.g. by forest tractors.

Part of the piled wood harvested in above manner, is converted into wood chip either in the timber yard by means of a movable chipping machine or it transported unprocessed to a pulp mill where chipping is concentrated to a bigger chipping unit. Chipping machines of the s.c. master's series, are generally small tractor-mounted machines getting their driving power from the power take-off of the tractor and by means of which forest owners, making delivery loggings, can produce wood chips themselves of trees of own harvest.

Apparatus related to converting standing trees into wood chip are known a.o. from US patents No. 3,651,845 and 3,646,976. They are not applicable for thinning, since their chipping method is space-taking or they cannot be driven close to the tree. They are practicable for for converting either a single tree in a clearing or all directly oncoming trees into wood

chip, but it requires quite a passable terrain.

By means of a chipping vehicle as per the invention, a fundamental advantage is achieved compared with said disadvantages. In order to put this method into practice, the chipping vehicle of the invention is characterized in what has been presented in the enclosed patent claims 1 and 5.

It can be considered the most important advantage of method and apparatus of this invention that handling a tree to be converted into wood chip is carried out in stage, which means that the delivery time of wood chip from forest to pulp mill can be reduced to a minimum. Likewise, the working conditions of workers converting trees into wood chip are improved remarkably, whereby lack of labor prevailing in the wood thinning sector can be eased through making the working conditions less stressing. In addition, according to the method of the invention, the convertion into wood chip can be done with trees in standing position, whereby damage to surrounding trees is also reduced to a minimum. The mobile boom and the chipping unit at its head can be of relativley light construction since the tree is in no stage hanging from the boom. Thus the boom can reach rather far and the vechicle must not be moved very often. The wood chip container can also be of exchangeable type.

In the following the invention is defined with reference to enclosed drawings:

Fig. 1 shows the chipping vehicle.

Fig. 2 shows the cutting and chipping unit of the chipping vehicle Fig. 3 shows the gripping and delimbing rolls of the tree to be converted into wood chip Fig. 4 shows the delimbing, debarking and chipping unit Fig. 5 shows the delimbing blades

Fig. 6 shows the cutting and chipping blade disc Fig. 7 is the cross-section of the chipping blade

Figure 1 illustrates a chipping vehicle 1 furnished with a chip container 2 and a hydraulic boom 3 with a chipping unit 4 at its top, by means of which a tree 6 to be converted into wood chip is cut and chipped in standing position, support rolls 16 holding tree upright and delimbing, steering and feeding it to the blade in the chipping unit. Produced wood chip is shifted along a conveyor 5 to the chip container 2. Chipping unit 4 is furnished with outriggers 8.

Figure 2 shows the chipping vehicle with a chipping unit with outriggers 8 and a tree gripping jaw 10 driven by a hydraulic cylinder 7. The jaw presses the trunk against part 11. The tree is cutted with a combination 13 consisting of chipping blades 25 on a saw disc which are manipulated by a hydraulic cylinder 9 and rotated by a hydraulic motor 12. The outer of edge of saw disc is formed as a circular saw. After cutting, blades 25 convert the standing tree into chips. At least during chipping, it is preferable to keep the blade blame assembly in slanting position, at angle of up to 45° with the tree. Produced chip is collected with a funnel receptacle 14 and shifted along conveyor 5 to wood chip container 2 on the chipping vehicle.

Figure 3 shows support and delimbing rolls 15,16, by means of which the trunk is kept upright and fed into the chipping unit while making chip. Rolls 15,16 delimbe the tree when it is fed downward upon chipping. In order to increase the delimbing effect, rolls 15,16 are in a position where the direction of their longitudinal axis deviates from the direction perpendicular to the longitudinal axis of the tree. Rolls 15 and 16 are fastened rotatably on levers 17,18 and the rolls can can be moved with relation to the tree in

turning the levers 17,18. Rotation of rolls is effected by means of a hydraulic motor.

Fig. 4 shows the chipping unit 4 with the blade disc 24 in slanting position, cutting the tree by means of its end bits 26 and chipping blades 25. Chip is produced already upon cutting and ejected by the blade assembly into a collector bin 23 from where it is shifted over, as described, to container 2. The container bottom 22 is robust and moves on the stub as cutting advances and, finally, carries the chipping unit 4 and the tree 6. The chipping unit is fastened to the boom arm 20 with cylinder 21. Blade bar 24 is fixed to frame member 19 by means of a bar 27, against the roll 28 of which the tree is supported. Turnable arms 29 are fixed to frame member 19 by an articulation 35. One of the arms 29 is behind the tree. The arms embrace the tree with a strong grip for support and put chipping unit into working position. The arms are furnished with hydraulically rotatable debarking rolls. After cutting, the tree is put into rotation by means of rotating and inclined feeding rolls 16. Feed roll arms 31 open and adjust according to tree diameter. Delimbing rolls 32,33 are fastened to same arms and are also adjustable according to tree diameter.

Figure 5 illustrates the delimbing blades and cross-section of blade 32 profile. Blades 32,33,34 can be spring-loaded, whereby leaned against the trunk they cut off oncoming limbs. The blades turn around a fulcrum pin 36.

Figure 6 illustrates a blade disc 24 with blade bits 26 along its edge and chipping blades 25 protruding from blade disc upper face. Wood chip is moved from the front of the blade through the disc to its underside and further into the collecting bin ejected by the winglike blade.

Figure 7 illustrates as cross-section of the fastening of blade 25 to the blade disc by means of an abuttment bit 35. The chips teared off the tree are slewed from the front of blade through the disc to the its underside.

Especially worht noting is the fact that the chipping unit can be furnished with a gripping element to take support from the stub and keep tree upright on the stub and by means of which tree can be lifted and supported during processing, for instance by means of hydraulic cylinders. The tree can be cut also by using a blade, which driven by great power power cuts the tree and then engages ti with the chipping blade. Anyhow, the invention is introduced here by referring only to one of its useful embodiments but many modifications are possible within the inventional idea determined by the following patent claims