The present invention covers a debarker with converging blades, with hydraulic and/or pneumatic control, used to separate the bark from sections of wood tissue, for example branches pruned from cork oak trees or branches and logs from felled cork oak trees, obtaining an output much higher than the current manual extraction and, at the same time, obtaining clean separated products, allowing a better profitability of the operations of the downstream industries, namely black cork agglomerate and charcoal .

The pruning, lopping of trees or air branches cleaning is a practice characteristic of the cork oak groves, creating the favourable conditions for a regular productivity, with the regenaration of the branches and the increase of the suberose production.

Besides these indirect advantages, the charges connected with their execution may be recovered through the value of the branches obtained, transformed into wood or charcoal and exploiting the cork in the industry of the black cork agglomerate.

The pruning takes place in Autumn and Winter, during the vegetative rest, and the cork is generally extracted in Summer. There is therefore a period during which the cork oak groves do not supply any work.

The paring is generally effected in the cork oak groves originally formed by trees of the same age, in order to enable the natural regeneration, or in cork oak groves densely covered with trees and also in dead or sick trees.

Nowadays, the remainings either of the pruning or the paring are piled up and the cork is, later on, manually

extracted, using axes or adzes, thus obtaining a -product formed of pieces of a product, which is a mixture of suberose tissue, inner bark and some pieces of woody tissue and, on the other side, the timber, both having very different dimensions. The return of this extraction is very low.

The pieces obtained from the extracted product are used for the production of black cork agglomerate and, for the purpose, they must be grinded and cleaned of impurities, inner bark and woody tissue, the latter raising problems with the production of this agglomerate, as the used procedure originates nodules of charcoal which originate the self- -combustion of the agglomerate during the laste phase of production.

The stumps of wood are sold as they are, fore firewood, or are transformed in charcoal in carbonization furnaces.

In other forest species, the clean debarking is difficult, but it is much seeked, considering the further uses of respective products.

The present invention cancels the mentioned inconve- niences, as it allows the processing of stumps of different diameters with the same length or with different lengths. When pushed through a set of disks, these are debarked as a banana, thus obtaining a clean stump and strips of bark.

If the stumps are cut into small pieces, the wood is ideal for fireplaces and can be sold at a higher price, therefore the extra cost required for cutting is fully compensated by the increased value originated. On the other side, the fact that the cork does not have any wood attached avoids certain problems in the production of the black cork agglomerate, the same thing happening with the other barks from other trees.

Another advantage is the fact that, with the machine,

a higher extraction output is obtained, by comparison-with the manual operation (wich tends to be abandoned, as well as the pruning, due to the raise of the costs of manpower) , thus enabling the operations aiming at a better production of the cork and the utilization of relevant quantities of timber and cork. This machine can be adapted to a farm tractor, the men being thus busy in the fields during the "dead" periods.

Hereunder, there is a detailed description, as illustra¬ tion and without a limitative character, of a preferred embodiment of the present invention, as illustrated on the attached drawings, on which:

Fig. 1 represents the machine with hydraulic or pneumatic control, according to the invention, which includes one steel ring (1) , one set of hydraulic or pneumatic cylinders (2) and a set of sharpenned steel disks (3) for cutting, alternating with blunt disks for centering and guiding;

Fig. 2 represents the debarking body, formed by a steel ring (1) with adequate thickness, with a central hole. This steel ring is used as support for the hydraulic or pneumatic cylinders (2) which drive the circular blades

(3) for cutting or centering, alternatingly placed; on the opposite side of the centering blades on the other side of the thin rubber ring are placed the hydraulic or pneumatic cylinders, which drive cutting blades;

Fig. 3 represents an alternative system, in which the hydraulic or pneumatic cylinders (2) are placed between two thin metal rings (1) ;

Fig. 4 represents the general lay-out of the machine with the feeding system formed by a conveyor belt (5) and transportation cylinders (8) ; the cutting system formed by a thin steel ring to support the system (1) , hydraulic or pneumatic cylinders (2) , of variable

quantity, disks or blades for cutting and guiding (3) ; and the extraction system, formed by a set of cogwheels (6) or cogged belt (7) ;

Fig. 5 represents an alternative system, with manual feed, formed by an hydraulic or pneumatic cylinder (11) which pushes a piston (12) which in turn pushes the stumps of wood (9) through the blades (3) here placed between two thin steel rings (1) .

The hydraulic or pneumatic cylinders were placed between the two thin steel rings represented on Fig. 5 and screwed to them; there may be another body, axially placed in line and crosswise unlined. A single thin steel ring may also be used, as shown on Fig. 4, and the supporting cylinders and the disks may all be at the same level or at different levels. Several consecutive debarking groups may also be used.

The axle of the cutting disks is placed at the end of a shaft (4) driven by an hydraulic or pneumatic cylinder (2) . When a stump approaches the central area of the machine, a detecting system drives the cylinders which remain closed. These cylinders act as a spring with a strong capacity of recovery and a high compression level . It should be stressed that the pressure can be regulated by means of an adjusting device. This pressure adjusting device is required because, depending on the type of stump, a stronger or weaker pressure will be required. Another aspect is that there is material with more or less bark thickness, in which case the pressure must be different, according to the situation.

In alternative to the cutting disks, blunt disks may also be used, acting as guides and making easier the centering of the stumps relatively to the cutting disks.

The feeding system may be formed, for example, by a conveyor chain and transportation cylinders, of adjustable pressure, as per the diagram on Fig. 4. There may also be a

stump traction system, after the debarking system, formed, for example, by cogwheels with the independent movement, as per Fig.4.

Alternatively, there may be manual feeding, in which case, it will be formed by only one double effect hydraulic system with respective support, as shown on Fig. 5. This cylinder develops the convenient force enabling the stumps to pass through the disks. At the end of the cylinder, a base can be installed, to allow a larger area to push the stump.

The operation of the machine is very simple, as human mediation is limited to placing the wood for debarking into the feeding system. When the stumps are conveyed and when the systems to put the disks into operation, converging blades which close, are set in motion, the bark of the wood is cut lengthwise by the cutting disks installed on the thin steel rings. At the outlet of each stump, the strips of bark remain and the clean wood comes out .

It is to be stressed that this machine obtains very good results with stumps of pruned branches of cork oak and eucalyptus, being the ideal machine for this type of material.

The output of the machine is higher than the manual extraction and its cost is quickly recovered.