WO1999000232A1

WO1999000232A1 - Device for producing strands

Info

Publication number: WO1999000232A1
Application number: PCT/EP1998/003899
Authority: WO
Inventors: Hans Dietz
Original assignee: Esterer Wd Gmbh & Co.
Priority date: 1997-06-27
Filing date: 1998-06-25
Publication date: 1999-01-07
Also published as: DE19828445A1; AU8629998A

Abstract

The invention relates to a device (1) for producing strands (51) from round wood, wherein the strands (51) are 200 to 350 mm long in the direction of the fibers, 0.5 to 3 mm wide perpendicular to the direction of the fibers and 15 to 40 mm thick. The device comprises a rotating chip remover (22) for cutting the strands out of the round wood. Preferably, the chip remover (22) is provided with a plurality of interspaced blades (30), each of which has a substantially radially directed cutting edge (31) for cutting out said strands. The chip remover (22) also has a gap (47) in the cutting edge area, which leads to an intermediate area (49) acting as a chip space. The device has first means (33, 60; 33', 60) assigned to the intermediate area for catching the strands and second means (70, 80) for catching large pieces which fail to enter the intermediate area.

Description

Device for making strands

The invention relates to a device for producing strands from round wood, the strands having a length between 200 and 350 mm in the fiber direction and a thickness between 0.5 and 3 mm and a width between 15 and 40 mm transverse to the fiber direction, with a rotating one Chipper for cutting out the strands from the round wood, the chipper being provided with a plurality of spaced-apart knives, each comprising a substantially radially oriented cutting edge for cutting out the strands, during which Cutting out the strands also produces coarse parts such as pieces of bark, broken-out wooden parts of an undefined shape and the like.

A device of the type mentioned above is known from DE 195 04 030 CI.

It is known to manufacture wood products e.g. Beams or planks instead of being made from shavings from solid wood. In addition to the known chipboard, products have become known which consist of so-called "strands", which are also referred to in technical terms as "afer" or "flakes".

This refers to wood chips with relatively large dimensions compared to wood chips or wood chips, e.g. when machining side areas, forest edges or the like. In contrast, strands typically have a length between 200 and 350 mm in the fiber direction and a thickness between 0.5 and 3 mm and a width between 15 mm and 40 mm transverse to the fiber direction. Wooden products are produced from these strands by joining and gluing, for example boards or beams, which are then referred to as "composite beams", "beach boards", "structural lumber products" or CSL (Construction Strand Lumber).

For this purpose it is also known to give the strands a specific shape with a defined width, length and thickness, possibly also with defined bevelled edges, so that the strands can be glued in a defined orientation to boards and beams. From the above-mentioned DE 195 04 030 CI a method and a device for producing such beaches are known. The log is a single tree trunk. The tree trunk is fed to a chipper device by means of a transport device. The chipper device can be brought into engagement with remaining areas outside a main article of the tree trunk, so that the beaches are cut from the remaining areas. The cutting tool used here is designed as a conical cutting disc. There are knives on the conical circumferential surface of the chipper disc, which have a main cutting edge in the radial direction and a secondary cutting edge in the circumferential direction. The chipper discs come into engagement with the tree trunk that has already been slit in the longitudinal direction (first step) and then make the necessary second and third cuts with the main and secondary cutting edges in order to cut out strands from the edge regions of the tree trunk.

A method and an apparatus for producing strands are also known from US Pat. No. 4,681,146. In this case, a rotating, flat chipper disc is used, which is provided with a total of six large, radially oriented knives in its flat surface. The knives are arranged in the manner of planer knives in the flat surface of the rotating tool. This means that before the cutting of the knives only narrow gaps are provided for the passage of the cut strands. A chip space is located below this column, which opens obliquely to the cutting direction at a very acute angle of approximately 5 °. There is a conveyor underneath the chipper disc derband that transports the cut strands into downstream processing areas.

The disadvantage of this known device is that, in addition to the desired cut-out beaches, the conveyor device also has corner pieces broken out of the log, for example. Such parts, called coarse parts, arise in particular when discontinuous areas of the round timber are machined, for example in the transition area to outgoing branches and twigs. The coarse parts placed on the conveyor impair the homogeneity of the quantity of wooden parts (strands and coarse parts) produced, so that the quality of the products made from the wooden parts suffers as a result. If the wooden parts produced are sold as an intermediate product, the achievable price is reduced if there are also coarse parts under the strands.

Against this background, the object of the invention is to further develop a device of the type mentioned at the outset in such a way that the homogeneity of the quantity of wooden parts produced is improved, so that the quality of the products made from the beaches can be increased or higher prices can be achieved.

This object is achieved according to the invention in a device of the type mentioned at the outset in that means are provided within the device for separating the strands from the coarse parts immediately after the strands have been cut out.

The object underlying the invention is completely achieved in this way. The fact that on the one hand means for catching the strands and on the other hand means for catching the coarse parts can be prevented in a structurally simple manner that coarse parts do not even get into the amount of the strands produced.

In a preferred embodiment of the invention, the chipper has a gap in the area of the cutting edges which opens into an intermediate space serving as a chip space, and there are a first means assigned to the intermediate space for catching the beaches and a second means for catching not the Coarse parts are provided.

The first and second means provided thereby enable the beaches to be separated from the unwanted coarse parts. The quality of the beach "mass" available for further processing can thus be increased without having to carry out subsequent sorting work.

In an advantageous development of the invention, the first means comprises an interior space delimited by at least one wall surface, the first means being arranged in a stationary manner in such a way that the intermediate space is connected to the internal space, so that strands reach the interior from the intermediate space. The wall surface is preferably designed as an essentially semi-cylindrical outer surface and has an opening in the lower region through which strands can fall out of the interior. Alternatively, the wall surface is composed of flat partial surfaces, resulting in a surface approximating the cylindrical surface. This has the advantage that a closed connection can be constructed in a structurally simple manner, which ensures that coarse parts cannot get into the "stream" of the strands produced.

In an advantageous development of the invention, the first means comprises a first conveyor unit for transporting beaches, preferably a section of the first conveyor device extending below the opening, and preferably the conveyor device comprising a cover in the region of the other section.

This has the advantage that no coarse parts can get into the conveyor. This is particularly important if the conveyor runs in the immediate area of the chipper.

In an advantageous development of the invention, the second means comprises a stationary deflection element, which is arranged in the cutting area and deflects coarse parts in a certain direction, preferably downwards. The second means preferably comprises a second conveying device, a section of the second conveying device lying in the region of the deflecting element, so that the deflected coarse parts reach the second conveying device.

This has the advantage that the coarse parts can also be collected and transported to a downstream area. This prevents coarse parts from contaminating the system and possibly causing malfunctions. In an advantageous development of the invention, the spaces widen in the radial direction and the knives are provided with cover elements, the cover elements for holding the coarse parts covering the spaces, leaving a gap between the cutting edges and the cover elements for the passage of the beaches.

This has the advantage that, due to the spaces widening in the radial direction, relatively large chip spaces are made available. A jamming of pieces of wood in these chip spaces is practically impossible. This is also due to the fact that the chips in such rotating chippers naturally fly out of the chip spaces under the action of centrifugal force. If the chip spaces widen radially outwards, the chips are accelerated by the centrifugal force in a direction in which even initially stuck pieces of wood loosen again.

Since, on the other hand, the presence of an excessively large chip space could result in coarse parts running through the tool to an undesired extent, for example small branches and fragments of bark and the like, the covering elements are provided with which the spaces can be covered so far that the required passage cross sections can be set for the respective application.

It is particularly preferred if the cover elements are chamfered on their underside towards the gap in order to enlarge the chip spaces. This measure has the advantage that the chip passing through the gap can exit almost freely, so that there is no need to fear jamming in this area. So, for example, while in the prior art the cut chip enters a very narrow wedge-shaped chip space, which is also formed with a constant width in the radial direction, the beveling of the cover elements allows an angle of entry for the chip into the chip space, which is, for example, at over 110 ° can lie. It is obvious that the risk of jamming due to chips can be practically excluded.

In a preferred embodiment of the device according to the invention, the cover elements are attached to the knives.

This measure has the advantage that e.g. the fastening elements (screws) provided for the knives can also serve to fasten the cover elements.

It is further preferred if the cover elements also serve as pressure elements and press the round timber against them in the area of the cutting edges, in particular in that the white elements acting as pressure elements have a pressure edge arranged essentially parallel and spaced from the cutting edge.

In this way, unwanted cracks in the cut strands are avoided.

It is further preferred if the cover elements are adjustable relative to the cutting edges. This measure has advantages with regard to both the masking function and the printing function. This is because not only can the passage cross-sections be set as desired by changing the covering of the interspaces, but rather the pressure force exerted in each case can also be adjusted when the cover elements are used as pressure elements.

In an advantageous development of the invention, the knives are arranged on a conical surface of the chipper, the conical surface enclosing the intermediate space.

It is further preferred if the knives are arranged along a spiral line on a surface of the chipper.

Further advantages result from the description and the attached drawing.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination indicated in each case, but also in other combinations or on their own without departing from the scope of the present invention.

The invention will now be explained in more detail using an exemplary embodiment with reference to the drawing. Show it:

Ia is an extremely schematic view of a wood cutting plant for tree trunks, in which a device according to the invention is used; FIG. 1b shows a section of the device shown in FIG. 1a according to an alternative embodiment;

FIG. 2 shows a schematic side view of the wood-cutting installation according to FIG.

3 shows a plan view of a chip surface of a chipper.

Fig. 4 is a view on the line IV-IV of Fig. 3 on a greatly enlarged scale;

5 shows a schematic sectional illustration of a chipper according to a further exemplary embodiment; and

6a, b

is a schematic sectional view of a section of the chipper shown in Fig. 5.

FIG. 1 a shows a device for the production of strands from tree trunks, designated by reference number 1, as is already described in substantial parts in DE 195 04 030, to which reference is made for further details.

For processing a tree trunk 10 or a corresponding log, this is preferably advanced with its thin end 11 forward by means of transport, not shown. In the cross-section of the tree trunk 10, the so-called main goods 12, for example a squared timber, is shown in dash-dot lines with 13 the remaining areas are indicated, in which the tree trunk 10 consists predominantly of non-processable wood and / or forest edges. The remaining areas 13 are those that are to be processed into strands.

For this purpose, longitudinal cuts 15 are made in the area of the remaining areas 13 on the tree trunk 10. For this purpose, the tree trunk 10 is passed in a transport direction 20 with one end, preferably the thin end 11, past the lateral cutting knives 21.

After passing the cutting knives 21, the tree trunk 10 arrives in the region of two laterally arranged chippers 22. The cylindrical chippers 22, which are designed with mirror symmetry to one another, are of conical shape, the end facing the tree trunk 10 having the smaller diameter. The chippers 22 are driven by means of a shaft 23, which is symbolized by an axis 24. The direction of rotation of the chipper 22 is indicated in Fig. Ia with an arrow 25.

Knives 30 are located on the conical chipper surface, each of which has a main cutting edge 31 oriented in the direction of rotation and a secondary cutting edge 32.

Both chippers 22 have a collecting unit 33 on their side facing away from the tree trunk 10. In the present exemplary embodiment, the collecting unit 33 comprises a wall 34, which is initially semi-cylindrical in the upper region and then runs straight down and which encloses an interior 35. The cylinder wall 34 is arranged in a stationary manner, the axis of the cylinder wall 34 coinciding with the axis 24 of the chipper 22. The collecting unit 33, ie the cylinder wall 34, is aligned with respect to the chipper 22 such that the circumferential gap resulting between the chipper and the cylinder wall 34 is so small that strands cannot pass through.

The collecting unit 33 is designed to be open towards the bottom, the opening thus created being designated by the reference symbol 36. The opening is dimensioned in such a way that the beaches entering the interior 35 can fall freely out of the collecting unit 33 following gravity.

Depending on the application, the interior 35 can be covered toward the long side facing away from the tree trunk 10 by a cover - which is not shown in the figure. However, the long side of the collecting unit 33 facing the chipper 22 is open, so that the strands made by the chipper 22 can reach the interior 35 of the collecting unit 33 from the inside of the chipper 22 in the direction of the axis 24.

A transport unit 60 is provided below each of the two collecting units 33, only one transport unit 60 being shown in FIG. 1 for reasons of clarity. In the present exemplary embodiment, the transport unit 60 comprises a conveyor belt 61 which conveys in the direction of the arrow 62. The transport unit 60 extends into a downstream area, which is not shown in FIG. 1 and in which, for example, a collecting container can be placed. Of course, other processing areas can also be provided instead. The transport unit 60 is provided at least in the area of the chipper 22 with a cover 63 which ensures that no foreign parts can fall onto the conveyor belt 61 from above. However, a recess 64 is provided in the cover 63 directly below the opening 36 of the cylinder wall 34, so that the strands produced can reach the conveyor belt 61 from the interior 35 through the opening 36.

A deflection unit 70 is attached to each of the two collecting units 33, only one deflection unit 70 being shown in FIG. 1. For the sake of clarity, the deflection unit 70 on the front collecting unit 33 has not been shown.

The deflection unit 70, starting from the collecting unit 33, initially extends downward in the opposite direction to the transport direction 20 and after a predetermined distance. The deflection unit 70 is arranged and dimensioned such that it is as close as possible to a side edge of the tree trunk 10. In addition, the deflection unit 70 is attached in an upper region of the collecting unit 33. The deflection unit 70 has the task of intercepting the coarse parts that arise during machining and guiding them downwards. With the aid of the deflection unit 70, it should be avoided that such coarse parts are thrown away from the device 1 by the rotating chipper 22.

To transport the deflected coarse parts, a further transport unit 80 is provided below the deflection unit 70, which is essentially identical to the first transport unit 60. In contrast, the transport unit points 80, however, there is no cover so that coarse parts can fall onto a conveyor belt (not shown) along the entire transport unit, in order then to be transported away in the direction of arrow 62.

An alternative embodiment of the collecting unit 33 'is shown in FIG. In contrast to the collecting unit 33, the wall 34 'with flat partial surfaces placed against one another is only approximated to a cylindrical shape. In this embodiment too, however, the side of the collecting unit 33 ′ facing the transport unit 60 is designed to be open, so that the strands can get into the transport unit 60 unhindered. Of course, the collecting unit 33 'can also be constructed from more than the five flat partial surfaces shown in FIG. 1b.

As already described in connection with FIG. 1a, the long side of the collecting unit 33 'facing away from the tree trunk 10 can be covered with a cover, so that the interior 35 is only open at the bottom.

The operation of the collecting unit 33 'shown in FIG. 1b does not change due to the different shape of the wall 34'.

2, the chipper 22 lying on the right in FIG. 1 is shown again in a front view. It can be clearly seen that the deflection unit 70 is connected to the collecting unit 33, so that the deflection unit 70 is also arranged in a stationary manner. The arrows 82 shown in FIG. 2 are intended to indicate that the parts of gravity entering the interior 35 follow the transport unit 60 and the others Parts get into the transport unit 80. This means that the strands generated by the knives 30, the construction of which is explained in more detail below, can reach the interior 35 in a radial direction from a space enclosed by the chipper and from there to the transport unit 60. The centrifugal force acting on the beaches causes them to migrate in the direction of the collecting unit 33 and ultimately reach the interior 35. Since the collecting unit 33 is arranged stationary, the strands lose their kinetic energy obtained by the rotation of the chipper and fall downward into the region of the opening 36 following the force of gravity.

Coarse parts, which are torn out of the round wood by the knives 30, do not get into the intermediate space of the chipper 22, but rather are thrown away by the rotation of the chipper. By means of the corresponding arrangement of the deflection unit 70, these coarse parts which have been thrown away are braked and directed downwards in the direction of the transport unit 80.

Of course, both the deflection unit 70 and the collecting unit 33 can be constructed in a different construction and while maintaining the function described above. The decisive factor here is that the strands produced are removed separately from the coarse parts, so that the most homogeneous strand mass is available for further processing.

Fig. 3 shows a plan view of the conical chipper surface. It can be seen that the knives 30 are arranged on this surface along a spiral line 40. The details of the knife 30 should now be based on the greatly enlarged Section 42 in Fig. 3 and the sectional view of FIG. 4 are explained in more detail.

As can be easily seen, the knives 30 are in the radial direction on the spiral line 40, i.e. each arranged approximately at a right angle to this. The division of the knives 30 along the spiral line 40 is denoted by α. If e.g. 25 knives 30 are arranged along the spiral line 40, the angle α is of the order of 14.5 °.

As can be clearly seen from FIG. 4, each knife 30, 30a, 30b, 30c is fastened by means of screws 43 to a disk body 44 of the chipper 22, which is only indicated schematically. For this purpose, the disk body 44 can be provided with corresponding projections, ribs or the like.

Cover elements 45a, 45b, 45c are also fastened to the knives 30, 30a, 30b, 30c. The cover elements 45a, 45b, 45c extend in the direction of rotation (arrow 25) of the chipper 22 in each case “backwards” away from the knife 30a, 30b, 30c and run out at their rear end into a pressure edge 46a, 46b which is essentially parallel to the Cutting edge 31, 31b, 31c of the knife on which the cover elements 45a, 45b, 45c are arranged.

In this way, a gap 47a / b, 47b / c is formed between the pressure edge 46a, 46b and the cutting edge 31b, 31c of the knife 30b, 30c lying behind it in the direction of rotation (arrow 25), as shown in the detail 42 in FIG. 3 is clearly recognizable. Arrows 48, 48 'in FIG. 4 indicate that the cover elements 45a, 45b, 45c are adjustable relative to the knives 30a, 30b, 30c on which they are fastened, specifically in the circumferential direction (arrow 48) , for example in the cutting plane, as well as in the axial direction (arrow 48 ').

The size and shape of the gap 47a / b, 47b / c can consequently be changed by moving the cover elements 45a, 45b, 45c.

By adjusting in the direction of arrow 48 ', the axial distance d _x between the pressure edge 46a, 46b and the cutting edge 31b, 31c opposite it can be set.

At a distance d _{2, it} is also indicated in FIG. 4 that the cover elements 45a, 45b, 45c are provided with a run-on slope opposite to the direction of rotation, as will be explained below.

Since the knives 30, 30a, 30b, 30c, as already mentioned, are preferably located on projections or ribs of the disk body 44, there are chip spaces 49a / b, 49b / c between the knives 31a, 31b, 31c, which on the one hand are characterized by the Extend the disk body 44 inwards and, on the other hand, open radially outwards, as the cutout 42 clearly shows in FIG. 3.

To enlarge the chip spaces 49a / b, 49b / c, the cover elements 45a, 45b, 45c can be provided with a bevel 54 on their underside in the area of the pressure edges 46a, 46b. In this way, an entry angle β for the chips into the chip spaces 49a / b, 49b / c is realized, which can be significantly above 100 °. If, as shown at the top right in FIG. 4, the round wood 10 is guided over the chipper 22 in the conveying direction 20, the underside of the round wood 10 runs on the upper side of the cover element 45a. It then reaches the run-up slope in the transition to the pressure edge 46 and is consequently compressed at this point. Since the cutting edge 31b of the knife 30b is at a distance d _x above the pressure edge 46a, a chip 50 is cut out of the round wood 10, which then runs through the gap 47a / b. As soon as the chip 50 is separated, the beach 51 thus produced enters the chip space 49a / b and is conveyed out of the chipper 22 in a direction 52 (axial) and / or by centrifugal force in the radial direction (arrow 53), so that it enters the interior 35 of the collecting unit 33.

As can be easily seen, therefore, by adjusting the cover elements 45a, 45b, 45c in the direction of the arrows 48 and / or 48 ', both the size of the gaps 47a / b, 47b / c and their shape, and in particular also the overlap of the chip spaces 49a / b, 49b / c can be set.

5 shows another embodiment of a chipper 22 '. In contrast to the chipper 22 shown in FIG. 1a, the chipper 22 'comprises a flat disk 90 which runs in a circular housing 91. A number of knives 30.1 'to 30.n' are arranged on this flat disk 90 on a spiral line around the axis 24. 5 clearly shows that the radially outer knife 30.1 'has the smallest distance from the disk 90 and the radially inner knife 30.n' has the greatest distance from the disk 90. This results in one of the conical shapes of the Spaners 22 according to Fig. Ia corresponding conical envelope of the knife 30 '. The strands produced with the aid of this chipper 22 ′ pass through the disk 90 into the interior of the housing 91, as is indicated by the arrow 92. The strands entering the housing 91 then fall onto the conveyor belt 61 of the transport unit 60 shown in FIG. 1a, as indicated by an arrow 93 in FIG. 5. The coarse parts, on the other hand, do not get through the disk 90 into the interior of the housing 91, but, as indicated by an arrow 94, fall down into the transport unit 80 shown in FIG. 2.

6a and 6b show sections of the disk 90 according to FIG. 5.

6a shows a section of the disk 90 along a radially extending cutting line, the axis 24 on the right-hand side and a radially outer region of the disk on the left-hand side. A chip catch 95 is assigned to the schematically indicated knife 30 'and is screwed to the knife holder on the radially outer side of the knife 30'. The chip catch 95 extends from a screwing area lying in a recess at an angle to the surface of the disk 90 and in the direction of the axis 24. The chip catch 95 ends below the main cutting edge 31. The chip catch 95 serves to remove the strands entering the knife gap radial direction to catch, so that they can not fly following the centrifugal force in the radial direction.

6b shows a section of the disk 90 as a section along a spiral line around the axis 24. Three knives 30.a ', 30.a + 1', 30.a + 2 'can be clearly seen, the knife 30.a + 2' lying in the radial direction on the inside and the knife 30.a 'further out. The chip catch 95 assigned to the individual knives, which extends over the entire width of the secondary cutting edge 32, can be clearly seen in each case. Furthermore, the main cutting edges 31 can be seen in FIG. 6b, each of which protrudes beyond the chip catch 95.

It goes without saying that the construction of the previously described collecting unit 33, the deflection unit 70 and the chip catch 95 are chosen purely by way of example. Of course, other configurations of the two units 33, 70 are also conceivable without departing from the scope of the invention.

Claims

claims

Device for producing strands (51) from round wood, the strands (51) having a length in the fiber direction of between 200 and 350 mm and a thickness between 0.5 mm and 3 mm and a width between 15 mm and 40 mm transverse to the fiber direction comprising a rotating chipper (22) for cutting out the strands (51) from the round timber (10), the chipper (22) being provided with a plurality of spaced-apart knives (30, 30a, 30b, 30c), each of which comprise an essentially radially directed cutting edge (31, 31a, 31b, 31c) for cutting out the strands (51), coarse parts such as pieces of bark, broken-out wooden parts of undefined shape and the like being additionally produced during the cutting out of the strands (51), characterized in that that means are provided within the device for separating the strands (51) from the coarse parts immediately after the strands (51) have been cut out.

Apparatus according to claim 1, characterized in that the chipper (22) in the area of the cutting edges (31, 31a, 31b, 31c) each has a gap (47a / b, 47b / c) which leads into an intermediate space (49a / b, 49b / c) and that a first means (33, 60; 33 ', 60) assigned to the intermediate space for catching the strands (51) and a second means (70, 80) are provided for collecting coarse particles which do not enter the intermediate space.

3. Device according to claim 2, characterized in that the first means (33, 60; 33 ', 60) comprises an interior (35) delimited by at least one wall surface (34; 34'), and in that the first means (33, 60; 33 ', 60) is arranged in a stationary manner such that the intermediate space (49a / b, 49b / c) is in communication with the internal space (35), so that strands (51) from the intermediate space into the internal space (35) reach.

4. The device according to claim 3, characterized in that the wall surface (34) is designed as a substantially semi-cylindrical outer surface and has an opening (36) in the lower region through which strands (51) from the interior (35) can fall outwards .

5. The device according to claim 3, characterized in that the wall surface (34) is composed of several flat partial surfaces, and that the wall surface (34 ') has an opening (36) in the lower region, through the strands (51) from the interior (35) can fall outwards.

6. Device according to one of claims 2 to 5, characterized in that the first means (33, 60) comprises a first conveyor unit (60) for transporting beaches (51).

7. The device according to claim 6, characterized in that a portion of the first conveyor (60) extends below the opening (36).

8. The device according to claim 7, characterized in that the first conveyor (60) in the region of the other section comprises a cover (63).

9. Device according to one of claims 2 to 8, characterized in that the second means (70, 80) comprises a stationary deflection element (70) which is arranged in the cutting area and deflects coarse parts in a certain direction, preferably downwards.

10. The device according to claim 8, characterized in that the second means (70, 80) comprises a second conveyor (80), a portion of the second conveyor (80) in the region of the deflecting element (70), so that the deflected coarse parts get to the second conveyor (80).

11. The device according to one or more of the preceding claims, characterized in that between adjacent knives (30, 30a, 30b, 30c) preferably radially widening gaps (49a / b, 49b / c) are provided as chip spaces that the knives ( 30, 30a, 30b, 30c) are provided with cover elements (45a, 45b, 45c), and that the cover elements (45a, 45b, 45c) for keeping the coarse parts away the gaps while leaving the gap (47a / b, 47b / c) cover between the cutting edges (31, 31a, 31b, 31c) and the cover elements (45a, 45b, 45c) for the passage of the strands (51).

12. The apparatus according to claim 11, characterized in that the cover elements (45a, 45b, 45c) to enlarge the Chip spaces are chamfered on their underside towards the gap (47a / b, 47b / c).

13. The apparatus according to 11 or 12, characterized in that the cover elements (45a, 45b, 45c) on the knives (30, 30a, 30b, 30c) are attached.

14. The device according to one or more of claims 11 to 13, characterized in that the cover elements (45a, 45b, 45c) also serve as pressure elements and press the log in the area of the cutting edges (31, 31a, 31b, 31c) against them.

15. The apparatus according to claim 14, characterized in that the cover elements (45a, 45b, 45c) acting as pressure elements have a pressure edge (46a, 46b) arranged essentially parallel and at a distance from the cutting edge (31, 31a, 31b, 31c).

16. The device according to one or more of claims 11 to 15, characterized in that the cover element (45a, 45b, 45c) is adjustable relative to the cutting edges (31, 31a, 31b, 31c).

17. The device according to one or more of the preceding claims, characterized in that the knives (30a, 30b, 30c) are arranged on a conical surface of the chipper (22), the conical surface preferably enclosing the intermediate space.

18. The device according to one or more of the preceding claims, characterized in that the knives (30a, 30b, 30c) are arranged along a spiral line (40) on a surface of the chipper.

19. The device according to one or more of the preceding claims, characterized in that each knife (30a, 30b, 30c) is assigned a chip catch (95) which catches the separated beaches.

20. The apparatus according to claim 19, characterized in that each chip catch (95) on the radially outer side of the knife (30a, 30b, 30c) is arranged.