WO2000043176A1

WO2000043176A1 - Chipping tool

Info

Publication number: WO2000043176A1
Application number: PCT/EP2000/000492
Authority: WO
Inventors: Hans Dietz
Original assignee: Esterer Wd Gmbh & Co.
Priority date: 1999-01-25
Filing date: 2000-01-24
Publication date: 2000-07-27
Also published as: DE19902873A1; AU2543300A

Abstract

The invention relates to a chipping tool (10) which serves to chip wood, especially for producing three-dimensionally defined chips (strands). The chipping tool (10) comprises a disc body (12) which can rotate around an axis (15). The chipping tool (10) also comprises a multitude of chipping blades (20) which are distributed over a periphery (16) of the disc body (12). The chipping blades (20) freely protrude over said periphery (16).

Description

Cutting tool

The invention relates to a cutting tool for cutting wood with a disk body rotatable about an axis and with a plurality of cutter blades distributed over a circumference of the disk body.

A cutting tool of the type mentioned above is known from DE 20 31 635 A.

BESttriGU ÜSKÖPIE Chipping tools for cutting wood are known in different designs and for different applications. The chipping tools can be used to flatten tree trunks laterally, ie to remove the bark areas in the edge area of the tree trunks (the so-called "forest edge") and to give the tree trunk a geometrically defined contour. Chipping tools are also used to free boards sawn from tree trunks that still have a forest edge on the side. Such tools are also referred to as "trimming machiners". Cutting tools are also used to profile tree trunks for subsequent dismantling into boards, planks and the like. For this purpose, the chipping tools (profiling tools) are used to provide the logs in the longitudinal direction with a continuous corner, which then serves as a reference plane for the side boards to be separated.

DE 195 04 030 Cl discloses a device for producing strands. This is understood to mean wood chips that are three-dimensionally defined and have, for example, a width of 15 to 30 mm, a thickness of 0.8 to 3 mm and a length of 180 to 300 mm, these values being understood only as examples. Strands are used for the production of heavy-duty composite components, for example for the production of panels, boards and beams. The strands are glued to one another for the production of these components, their three-dimensionally defined shape allowing particularly good alignment of the strands when scattering. In the known device, the strands are not produced by completely chipping tree trunks or branches (as is also known), but rather by chipping or chipping side areas and corner areas of a tree trunk in a profiling system, the main goods remaining in the center having any dimension assume and can also be relatively small.

The production of strands is a preferred field of application of the present invention, but is not restricted to this field of application.

In conventional chipping tools of the type mentioned above, for example in the chipping tool according to the aforementioned DE 20 31 635, a disk body is used as a carrier for the chipper knife, which is rotatable about a central axis. In this known chipping tool, the disk body is a flat disk, but chipping tools are also known in which the chipping surface is conical. The disk body is designed to be continuous, but disk bodies are also known which are provided with openings for the passage of chips.

On the cutting side of the disk body, a plurality of essentially radially directed chipper knives are arranged at an axial distance such that the cutting edges of the chipper knives run essentially in the radial direction. The chipper knives are held on radially continuous fastening bodies at an axial distance from the chipper disk. Seen in the direction of conveyance of the wood, there is an abutment shortly before each blade or cutting edge is also referred to as a "counter knife". The chip separated from the cutting edge therefore enters the space between the cutting edge and the counter knife in the circumferential conveying direction and is additionally bent away from the machined wood and thus essentially in the axial direction. Since the fastening body of the cutting edge is located in the circumferential direction, that is, in the conveying direction of the chip, and furthermore in the axial direction below the mentioned gap of the disk body, there are radially directed channels between the cutting edges and counter-knives, the long sides of which through the fastening bodies and the underside through the disk body be formed. Since the cutting tools rotate at high speed, the centrifugal force is usually sufficient to convey the separated chips out through these radial channels. However, if the chips become longer and you are also interested in the most precise, three-dimensional shape of the chip, disadvantages can occur if the separated long chip first hits the fastening body with its front end, is bent there, then through the channel runs through, and finally hits the opposite body of the chipboard, where the chip is bent again. There is a high risk that the chip will be damaged as a result of repeated bending. It can also not be ruled out that, in particular, longer chips jam in the radial direction in the manner of a turning chip, so that the centrifugal forces which occur no longer suffice to challenge these chips from the cutting tool. This then leads to a clogging of the above-mentioned channels and, as a result of the congestion that occurs, damage to the wood, possibly to the cutting tool, but in any case to the chips produced, which then break or deform undefined. A cutting edge arrangement and a blade holder for a chipper are known from US Pat. No. 5,505,239. In the known arrangement, the shaft of the chipper tool is designed as a hexagonal profile. A mounting flange is arranged on each of the six surfaces of the profile and carries a blade holder. The blade holder extends inclined to the axial direction of the cutting tool and that radially obliquely outwards from its free end. The blade holders each carry a blade that also extends radially outward from the free end of the cutting tool. According to a first embodiment, the blade holder, which is triangular in radial view, is provided with a window through which the chips which are removed are to pass. According to a further exemplary embodiment, however, the blade holder is designed like a ladle, that is to say axially and radially continuously, so that the cut chips fly in the axial direction along the blade holder and can be disposed of after passing through the blade holder. In any case, the blade is solidly connected at both ends to the blade holder or the hexagonal shaft of the cutting tool. This means that the cut chips always encounter obstacles when they fly along the cutting edge of the cutting tool in the circumferential direction of the cutting tool.

From DE 20 31 635 a cutting disc for a wood chip machine is known. The cutting disc comprises a flat tool holder, on which, in a radial alignment, circular sector-shaped chip knives are arranged. These run slightly axially outwards in the radial direction. When this cutting tool rotates, the leading cutting knife acts as counter knife and the immediately following cutting knife acts as ,

Cut so that the cut chips enter the space between the counter knife and the cutting edge. As they get there, however, in the region of the radially continuous, disk-shaped blade carrier to face the aforementioned disadvantages ^* a share. The chips are forcibly bent and mostly broken.

The invention is based on the object of further developing a cutting tool of the type mentioned in such a way that these problems are avoided. In particular, it should be possible to build strands, i.e. to produce very long chips with a three-dimensionally defined shape without the disadvantages described occurring.

In the case of a cutting tool of the type mentioned at the outset, this object is achieved according to the invention in that the cutting knife protrudes freely from the circumference.

The object underlying the invention is completely achieved in this way.

If the chipper knives protrude freely from the disc body in the manner of turbine blades, then the chips that are cut off are subjected to practically no resistance at all, because the existing interference contour leads to the greatest possible freedom in the path of movement of the chips. In this way, chips of practically any length can be generated because the chips no longer hit any obstacles after the passage between the cutting edge and the counter knife. In a preferred embodiment of the invention, a first chip knife acts as a cutting edge and a second chip knife lying in front of it in the direction of rotation of the chip cutting tool acts as a counter knife, the arrangement of the freely projecting chip knives being such that a chip separated from the knife edge is without obstacles meet between the cutting edge and the counter knife.

This measure has the advantage that a geometry in the cutting tool is ensured in such a way that there is no longer any fear of mechanical impairment of the chips.

In a further preferred embodiment of the invention, the cutting knives have a fastening flange for fastening to the disk body and a blade carrier protrudes freely from the fastening flange.

This measure has the advantage that a particularly simple, single-ended fastening of the span knife is possible.

This applies in particular if, according to a summary of the above-mentioned exemplary embodiments, pockets are provided on the periphery for detachably holding the chipper knife.

This measure has the advantage that on the one hand a reliable fastening of the chipper knife is possible, but on the other hand the chipper knife can also be replaced individually if required, be it that a chipper knife is no longer functional or has to be reground regularly. In further developments of this exemplary embodiment, the fastening flanges can be fastened, in particular screwed, in the pockets.

It is further preferred if the blade carriers are either formed in one piece with the chip knives or are detachably fastened to the blade carriers.

In preferred configurations of the cutting tool according to the invention, this can be conical or even plane in a manner known per se, essentially to the axis.

It is further preferred if the circumference of the disk body is also designed in a spiral manner, in particular in a multi-course spiral manner, more preferably in a two-course spiral pattern.

These measures, which are known per se, have the advantage that it is possible to use known designs with the inherent advantages.

In further preferred embodiments of the invention it is provided that the chipper knives are provided with a cutting edge on an upper side and that a lower side is concave. It is further preferred if the concave underside has a radius of curvature that is greater than the radius of curvature of a chip separated by means of the cutting edge.

This measure has the advantage that within the constructive possibilities when designing the freely projecting machining The shape of the area of the chipper knife that is first arranged in the area of the path of movement of the split chip is optimized. If the underside is made concave in the manner described, there is therefore more room for movement for the separated chip. If the radius of curvature in the manner also described is greater than the radius of curvature of the cut chip, there can no longer be any obstructive contact between chip and chipper knife after leaving the cutting edge.

Furthermore, it is preferred in the chipping tool according to the invention if the chipper knives are arranged axially stepped in the circumferential direction in a manner known per se.

This measure has the advantage that the chipper knives distributed over the circumference engage one after the other with a defined axial distance in the wood, so that a defined shape (thickness) is possible in this coordinate direction.

Finally, further exemplary embodiments of the invention are preferred, in which the chipper knives are connected to one another at their free ends by a stiffening element, this stiffening element preferably being essentially annular.

This measure has the advantage that the mechanical bending load on the freely projecting chipper knives is reduced if they are gripped by their circumference without the movement space for the separated chips being impeded. 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.

Exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the following description. Show it:

Figure 1 is a plan view, partially in section, of a disc body, as used in a cutting tool according to the invention.

FIG. 2 shows a detail from FIG. 1 on a greatly enlarged scale;

3 shows a cutting tool according to the prior art;

Fig. 4 is an illustration, similar to Fig. 3, for explaining the cutting tool according to the invention.

In FIG. 1, 10 designates a chipboard with a disk body 12, which has a central fastening opening 14. The further fastening elements, in particular threaded bores for fastening screws and the like, are not shown for the sake of clarity. It is understood that through the fastening opening 14 a shaft of an Drive motor is sufficient, which can drive the chuck 10 at a predetermined speed and torque. The axis of rotation is designated 15.

The disk body 12 is divided into two rotationally symmetrical circumferential areas, each of which has a spiral circumference 16. The spirals can e.g. be formed as Archimedean spirals.

Pockets 18 are embedded in the periphery 16 on the periphery in the surface of the disk body 12.

If, in a practical embodiment, the chipping disk 10 has an outer diameter D of e.g. 1,430 mm and an inner diameter d of e.g. 750 mm, whereby these numbers are only to be understood as examples, so on both circumferences 16 e.g. twenty-five pockets 18 each are arranged.

It goes without saying that instead of two peripheral regions, three or four or even just one can also be provided. The number of pockets 18 can also be freely selected in a wide range.

One end of a chipper knife 20 is fastened in each of the pockets 18, for example by means of two fastening screws. The chipper knife 20 projects with its other free end freely over the circumference 16 of the disk body 12. The radial board is designated 1 in FIG. 1. In the exemplary embodiment defined in more detail above, the board 1 can be, for example, 250 mm. It is also indicated in FIG. 1 that the chipper knife 20 can, if necessary, be connected at its circumference to a stiffening element 21, which is preferably of annular design and holds the chipper knife 20 at its circumference.

An arrow 22 shows the direction of rotation of the chipping disk 10.

In Fig. 2 it is shown on a greatly enlarged scale that each chipper knife 20 comprises at the clamped end a mounting flange 30 which is preferably in a form-fitting manner 30 in a pocket 18. For fastening the chipper knife 20, the fastening flange 30 is fixed in the pocket 18 by means of screws 32.

A blade carrier 34 projects freely from the mounting flange 30, which e.g. is provided on its top with a blade 36. The blade 36 has a cutting edge 38 in the cutting direction (arrow 22).

It goes without saying that blade carrier 34 and blade 36 can also be in one piece, but an arrangement is preferred in which the blades 36 are designed as separate and thus interchangeable elements.

In order to illustrate the functioning of the tool according to the invention, FIG. 3 first shows an arrangement according to the prior art, for example according to DE 20 31 635 already mentioned at the beginning. In this known cutting tool, a cutting disk 50 with a circular disk body 52 is provided. The disk body 52 is arranged to be rotatable about an axis (not shown). Fastening bodies 54 protrude from the top of the disk body 52 and extend in the radial direction. Blade carriers 56 are screwed onto the inclined upper side of the fastening bodies 54, which in turn are provided with blades 58 on their upper side. The blades 58 are provided with cutting edges 60 at one edge. The cutting edges 60 likewise run in a substantially radial direction with respect to the shaving washer 50.

If a wood 66 is now passed over the chipping disk 50, a chip 68 is cut off by means of the cutting edge 60. The chip 68 is bent when it is separated and runs into a space 70, which is located on the disc body 52 as a radial channel between two fastening bodies 54 lying next to one another. The effective interference contour 72 is hatched in FIG. 3. It can be seen that the bent chip 68 can only move freely over a very limited distance in the circumferential direction of conveyance and in the axial direction (ie to the right or downward in FIG. 3). The chip 68 will therefore, as indicated in FIG. 3, first strike the next outer fastening body 54 in the circumferential direction (to the right) and be bent there in the axial direction (downward). It then hits the disk body 52 and is bent there again, namely in the radial direction, ie perpendicular to the plane of the drawing, as indicated by arrows 74 and 76, in order then to be ejected from the channel between the two adjacent fastening bodies 54 under the influence of centrifugal force. The chip 68 comes into contact with areas of the interference contour 72 several times and is deformed, if not damaged. This applies in a corresponding manner also to known chipper tools, for example according to US 5 505 239 A mentioned at the beginning. In the chipper tools described there, the chips always strike the fastening elements of the blades, which are connected to the fastening flange over their entire length.

4 shows the situation in the case of the cutting tool according to the invention with freely projecting blades or cutting edges.

If a wood 66 'is guided over the chipping disk 10, a chip 68' is cut off by means of the cutting edge 38. The chip 68 'enters the free space between the cutting edge 38 and the blade carrier 34 in front of it in the cutting direction, which in this case acts as a counter knife. The space 70 'below this gap, however, is completely free, in contrast to the prior art described, because the blade carriers 34 project freely, as already explained. The chip 68 'can thus freely (downwards in FIG. 4) spread out without being hindered by an interference contour. The interference contour 72 ', which is likewise hatched in FIG. 4, is namely outside the path of movement of the chip 68'. For this purpose, the underside of the blade carrier 34 is convex, the radius of curvature R of this convex region being greater than the radius of curvature r which is naturally formed when the chip 68 'is cut off.

Finally, it can be seen from Fig. 4 that the circumferential, i.e. in the cutting direction, successive blade carriers 34 are stepped in the axial direction, as indicated by z in FIG. 4.

Claims

claims

Cutting tool for cutting wood with a disc body (12; 52) which can be rotated about an axis (15) and with a large number of cutting knives (20) distributed over a circumference (16) of the disc body (12; 52), characterized in that the cutting knife (20) cantilever from handling (16).

Cutting tool according to claim 1, characterized in that a first cutting knife (20) acts as a cutting edge (38) and a second cutting knife (22) in front of it in the direction of rotation (22) of the cutting tool (10) on the circumference (16) acts as a counter knife, and in that the arrangement of the freely cantilevering knife (20) is such that a chip (68 ') separated from the cutting edge (38) passes between the cutting edge (38) and the counter knife without hitting any obstacles.

Cutting tool according to Claim 1 or 2, characterized in that the cutting knife (20) has a fastening flange (30) for fastening to the disk body (12; 52), and in that a blade carrier (34) projects freely from the fastening flange (30).

Cutting tool according to one or more of claims 1 to 3, characterized in that pockets (18) are provided on the circumference (16) for releasably receiving the chipper knives (20).

5. Cutting tool according to claim 3 and 4, characterized in that the fastening flanges (30) in the pockets (18) are fastened, in particular screwed.

6. Cutting tool according to one or more of claims 3 to 5, characterized in that the blade carriers are formed in one piece with the cutting knives.

7. Cutting tool according to one or more of claims 3 to 5, characterized in that the cutting knife (22) on the blade carriers (34) are releasably attached.

8. Cutting tool according to one or more of claims 1 to 7, characterized in that the disc body (12) is conical to the axis (15) substantially.

9. Cutting tool according to one or more of claims 1 to 7, characterized in that the disc body (12) is substantially flat to the axis (15).

10. Cutting tool according to one or more of claims 1 to 9, characterized in that the circumference (16) is spiral.

11. Cutting tool according to claim 10, characterized in that the circumference (16) is multi-helical.

12. Cutting tool according to claim 11, characterized in that the circumference is double-helical.

13. Cutting tool according to one or more of claims 1 to 12, characterized in that the chipper knife (20) are provided on one upper side with a cutting edge (38) and that an underside is concave.

14. Cutting tool according to claim 13, characterized in that the concave underside has a radius of curvature (R) which is greater than the radius of curvature (r) of a chip (68) separated by means of the cutting edge (38).

15. Cutting tool according to one or more of claims 1 to 14, characterized in that the chipper knife (20) are arranged axially stepped (z) in the circumferential direction.

16. Cutting tool according to one or more of claims 1 to 15, characterized in that the chipper knife

(20) at their free ends by a stiffening element

(21) are interconnected.

17. Cutting tool according to claim 16, characterized in that the stiffening element (21) is substantially annular.