EP1358980A2 - Two dimensionally effective knife for chipping machines as well as a device and method for its production and sharpening - Google Patents

Abstract

The knife blade (1) has an edge (3) chamfered at an acute angle to produce a sharp cutting edge (2). The sharp edge is broken by wedges (4) with sharp forward edges facing forward to cut chips coming off the cutting edge into short sections. The knife may be sharpened by a grinding wheel with a chamfered edge which shapes the wedges.

Description

The invention relates to a two-dimensionally effective knife for cutting machines, especially for wood-cutting machines, a device for producing and resharpening such Knife with at least one grinding tool as well corresponding process for manufacturing and resharpening such knife.

In cutting machines, logs and logs can be made defined wood chips are produced, which are then e.g. to wood-based panels or beam-shaped products be pressed. Cutting machines can also be found in the plastics processing application, e.g. for the production of granules. The following explanations therefore apply Cutting machines in general and are not limited on wood chip machines.

The nature of the chips produced determines the physical properties of the following produced materials, e.g. of wood-based materials, which in used in the construction and furniture industries.

Especially the use of those made from the chips Products in the construction industry with structural and stiffening functions makes the chips high quality in uniformity, surface quality and Edge sharpness necessary. This demand for a high However, chip quality can only be met if continuously optimally sharpened cutting in the cutting machines be used. A regular, quick one and economical changing and sharpening of the knives therefore essential for an optimal production process.

In addition to the properties of the end products, the The raw material yield is determined by the sharpness of the knives. Blunt knives produce fine material during the cutting process, which has to be screened and thus from the Production process is removed.

For the machining of logs and logs, in in recent years so-called knife ring chippers enforced.

In the housing of a modern wood cutting machine, e.g. of a knife ring chipper, there is a rotatable one stored knife ring (also as knife ring or basket referred to), which is preceded by a feed trough. In the logs in a discontinuous operation the rotating knife ring and clocked through the Knife ring passed by fiber course machined, whereby the cycle length is determined by the depth of the knife ring becomes. The circumference of the knife ring is even Distance knives arranged, their knives all intersect are on a common flight circle and inside are directed. The radius difference between the Radial circle radius of the knife edges and the larger radius the cylindrical inner wall of the knife ring determines the Chip thickness.

There are separate scoring blades on each knife with uniform axially spaced from each other, the cutting edges also describe an inward circle, whose radius is that of the knife edge (also main edge called), reduced by at least the chip strength, equivalent. This the main cutting edge by at least one Scribe blades that advance the chip thickness produce transverse to the Grain direction of the wood according to its arrangement ring-shaped grooves in the trunk wood, their distance from each other corresponds to the span length. The tribes become quasi immediately before the chips are cut perpendicular to the fiber incised to define the length of the chips.

So that the chip quality at a consistently high level it can be held that the Cutting machine always with sufficiently sharp knives is working. If the scoring blades become dull, that the proportion of the desired defined chips decreases, and the proportion of fines increases. This fines would affect the quality of the Wood panel so negatively affect it must be screened and thus loss of the raw material wood represents. Blunt scoring blades lower it Raw material yield. Due to the demand for always sharp knives, they must be changed regularly. In order to disturb the production process as little as possible it is necessary to change the knives as quickly as possible.

Various solutions have been developed in the past been around the knife rings of the cutting machine with fresh sharpened knives.

One option is to replace the Knife packages of a knife wreath. The knife packs exist from a knife holding plate, one detachable with this connected knives and several for example from the DE 80 28 362 U1 known scoring blades, which also are detachably connected to the main knife. To replace The production process is repeated several times a day Intervals interrupted. As in DE 35 05 077 A1 the knife ring from the cutting machine is described removed and against a second knife ring with sharp Knife packages exchanged. After this procedure the Cutting machine continue their production process, while the knife packages on the removed knife ring individually change.

The knives are used by the sharpening process Knife holding plates removed and after sharpening in one Adjustment device outside of the knife ring again with screwed the holding plates to knife packs.

A disadvantage of this construction of the knives or Knife packages is that before sharpening the main knife First all scoring blades have to be removed. would If they remain on the knife, a collision would occur the grinding tool working along the main cutting edge. There each knife set of a knife ring several hundred Scoring blades, the removal and after the Grind the scraper blades again represents considerable expenditure of time, which results in high Reflects personnel costs. Also the material costs attract attention because the scoring blades are quite complex Strip steel must be manufactured. The scoring blades are as Disposable knives designed and can not be economical be sharpened because they are too thin. To an optimal The scoring blades should ensure machining every sharpening process of the main cutting edge is replaced by new ones become.

To reduce material costs, the scoring blades are in often used in practice, which is true Reduces costs, but does not cut evenly allows. The proportion of fine goods increases, the committee in Production process increases and at the same time it decreases Quality of the board materials produced by frayed End faces of the chips produced.

It also represents replacing the whole Knife ring represents a considerable effort. This solution can therefore not be reliable and economical be considered.

Another way to cut the knife rings Cutting machines with freshly sharpened knives is provided in the patent specification DE 196 05 072 C1 described. The knife wreaths described are with Knives equipped with the mentioned, separate Scoring blades are firmly and permanently attached. Furthermore provides this possibility, the knives in the knife ring, So in the cutting machine itself, to sharpen the time-consuming exchange of the entire knife ring or to avoid changing knives.

For this purpose, an automatic grinding machine should be used, which is driven into the knife ring of the cutting machine in order to there in several steps first the main cutting edges and then grind the scoring blades. After an elevated Current consumption, caused by the dull Chip knife, the cutting machine machine is triggered has, it moves from the working position into the Maintenance position. One after the other, the plate-shaped Span knife, evenly spaced on the back Scoring blades with scoring organs are permanently attached, solved radially to the amount of wear inside the Knife ring pushed and reattached. A Grinding roller with the length of the chip knife and with evenly spaced ring grooves with the profile of the Scoring organs are used for sharpening chip knives and Ritz organs.

Sharpening takes place in two grinding phases. In the first Grinding phase with rotating knife ring and counter-rotating grinding roller the chip knife sharpened. The infeed of the grinding roller corresponds here the radial displacement of the chip knife.

This is followed by in a second grinding phase knife ring positioned step by step with each small axial movements of the rotating grinding roller Flanks of the scoring organs and those in the area of the ring grooves Remaining remains on the cutting edges of the chip knife abraded. After the grinding tool from the inside the knife ring is pushed out, the Return the machine to its working position and resume production.

The high costs of the complex are disadvantageous designed chip knife felt on the back now scoring blades with scoring organs are attached, especially because the chip knife has a very high Subject to wear and tear after only a few days which they have been sharpened again and again by new ones need to be replaced. For a change of the Production on a different chip length is not enough to replace existing grinding roller with a new one spaced according to the current span length Has ring grooves, but knives must also be covered be the scratching distances between the new requirement satisfy.

The time-consuming re-sharpening of the knives and the separate scoring elements in the chip machine would become one lead to significant loss of production, if not one second cutting machine positioned in front of the feed channel which would affect the production process during the Maintenance procedure continues on the first machine.

In addition to the immense technical effort, there must be two Cutting machines and two maintenance stations with one each Grinding tool and a knife adjuster installed, this solution also brings considerable grinding problems with it. So the high ones Requirements on the grinding result by the Vibration emissions of just a few meters away on the joint cutting machine producing cutting machine, that works with over 1000 kW drive power in some cases, destroyed.

In addition, the so-called burning of Knife cutting and scoring organs at the same time high Removal performance only during sharpening adequate cooling with grinding oil or emulsion countered become. It is therefore inevitable that, on the one hand, in the Maintenance phase coolant with residues of wood chips and Wood dust comes into contact, on the other hand in the Production phase the chips by residues of Grinding abrasion and coolant, which the inner walls of the Cling machine stick, become dirty. This has in in the first case, that is not ecologically safe coolant must be disposed of early, since organic substances are essential for the amount of Germ count, which indicates the service life of the coolant determines who are responsible. In the second case, you can Residual coolant in connection with the glue that forms the chips is added to unexpected chemical reactions to lead. The grinding abrasion can reduce the tool life in the wood panel processing industry. Here are usually very sensitive to metallic ingredients sensitive diamond cutters are used.

Finally, another problem arises from the Construction of the cutting machine and the associated Difficulties in the grinding process. The usually more the 600 mm length of the knives almost corresponds exactly the depth of the closed in the rear area Knife ring, so that a supportive bearing to catch the grinding forces on this side of the grinding roller can be realized. The one-sided storage of the Grinding roller, also called flying storage, is used both the quality of the cut, as well as the removal rate of the grinding tool.

The elementary problem of both solutions is that not that can be ensured in an economical manner sharp knives are always provided in the machine can be. Both the exchange of the complete Knife ring as well as sharpening it in the machine, if a second machine is provided, place one takes a lot of time. Especially with the second version can affect the quality of the cut and thus immediately connected the quality of the product is not guaranteed become.

The present invention is therefore the object based on the manufacture and resharpening of two-dimensionally effective knives for cutting machines, especially for wood chip machines, and thus the Optimize chip production.

This object is achieved by a two-dimensionally effective knife solved one Main cutting edge and at least one cutting edge, the knife and the cutting edges being made in one piece are.

By providing a knife that has a Main cutting edge and at least one cutting edge are provided are and that is made from one piece, is achieved that when changing the knives only one component each needs to be replaced instead of, as was previously the case, a whole knife package consisting of knife holder plate, knife and need to replace multiple scoring blades. Furthermore, that is Knives according to the invention without problems from grinding standard blades in one piece manufacture.

In addition, the above task is performed by a Device for producing and resharpening two-dimensionally effective knives for cutting machines solved, which is provided with a grinding tool that at least two arranged at an angle to each other Has grinding surfaces.

Finally, the task is completed by an appropriate one Process for manufacturing and resharpening solved in which a grinding tool is passed over the knife at least two arranged at an angle to each other Has grinding surfaces.

With the help of the device according to the invention or corresponding procedure can be in a single Work step both a main cutting edge and also at least one side of a cutting edge Knife manufactured or sharpened. In this way will also manufacture and maintain, especially that Sharpening, the knife significantly simplified.

Different from those known from the prior art Only the individual knives are moved, not the entire knife rings, at regular intervals Machine removed, and exchanged for sharp ones, so allow the production process to continue directly can. This can be done with a single machine and not, as in the prior art, with a Machine for production and one machine for maintenance. Also the mere exchange of the knives is a lot quicker and easier to perform than replacing the entire knife ring.

Preferred embodiments are in the subclaims remove.

Fig. 1

die Schneiden eines zweidimensional wirksamen Messers gemäß der Erfindung;

Fig. 2

die Seitenansicht eines erfindungsgemäßen Messers;

Fig. 3

einen Schnitt durch einen mit den erfindungsgemäßen Messern bestückten Messerkranz;

Fig. 4

einen vergrößerten Ausschnitt aus Fig. 3;

Fig. 5

eine schematische Darstellung des Zerspanvorganges;

Fig. 6

eine schematische Darstellung eines Schleifvorgangs mittels einer Schleifvorrichtung gemäß der Erfindung und

Fig. 7

eine schematische Darstellung eines Schleifvorgangs mittels einer weiteren Ausführungsform der erfindungsgemäßen Schleifvorrichtung.

The present invention is explained in more detail below on the basis of exemplary embodiments, reference being made to the drawings. Show in the drawing

Fig. 1

the cutting of a two-dimensionally effective knife according to the invention;

Fig. 2

the side view of a knife according to the invention;

Fig. 3

a section through a knife ring equipped with the knives according to the invention;

Fig. 4

an enlarged section of Fig. 3;

Fig. 5

a schematic representation of the cutting process;

Fig. 6

is a schematic representation of a grinding process using a grinding device according to the invention and

Fig. 7

a schematic representation of a grinding process by means of a further embodiment of the grinding device according to the invention.

The invention relates to a knife 1, which in Cutting machines, especially for wood cutting, is used. As shown in Fig. 1, according to the invention Knife 1 a main cutting edge 2 and several from the Open space 3 cut-off blades 4. The structure of the knife 1, in which the main cutting edge 2 and the Cutting blades 4 are made from one piece, has the decisive advantage that instead of a whole Knife package only exchanged a single knife 1 must become. The tedious dismantling is also eliminated of packages before grinding and assembling afterwards. In addition, the knife 1 is in one grinding Process step from commercially available standard blades manufacture. However, previously known methods see a complex, multi-component structure, whereby a high level of grinding technology arises.

Fig. 2 shows a side view of an inventive Knife 1. It can be seen that the cutting edges 4 neither on the top nor on the bottom of the knife 1 protrude. This construction allows when for example, a knife holding plate is provided, one easier assembly of the knife packs. Because of the special Shape, i.e. without over the contour of the knife 1 protruding elements, the handling of the knife 1 both inside and outside the machine much easier. Also easier resharpening Knife 1 in the machine or an automatic adjustment the knife 1 in the knife ring is conceivable.

Due to the inventive design can on holding plates also be dispensed with. Figures 3 and 4 show one Embodiment in which the knife 1 immediately, d. H. without additional holding plate, in the Knife ring is installed. Because on a holding plate can be dispensed with, and thus the knife 1 directly fewer components can be clamped. This increases the accuracy of the cutting machine because each component can only be manufactured with tolerances. So the more components used in a knife pack find, the greater the additive tolerances. These tolerances mean that in the prior art the Flight circle of the knife is not uniform and therefore chips of different thickness are produced, which further production process and the quality of the End product affected.

Figures 3 and 4 also show the operation of a Wood chip machine with a knife ring that matches the Knives 1 according to the invention is equipped. The knife wreath consists of a carrier disc and a carrier ring, between which the so-called knife carriers in are evenly spaced. In Fig. 3 there are three this knife holder shown. The knife ring is over a shaft connected to the carrier disk is driven, whose axis is perpendicular to the plane of the drawing. On each knife holder is designed according to the invention Knife 1 via frictional engagement by means of a clamping plate held that by rotating the knife ring the logs fed cyclically are machined. in this connection the knife ring moves in the infeed direction against the stationary part of the machine. By the before described cutting edges 4, the chips are cut to length.

4 is the functioning of the invention Knife 1 shown. As the knife ring turns, each cutting edge 4 scratches a groove in the part to be cut Wood and the main cutting edge 2 separate the finished chips. The distance between the cutting edges 4 corresponds to that later chip length L. By the knife board is the Chip thickness defined.

Fig. 5 shows schematically the machining process. The Cutting edges 4 scratch the trunk in the example shown into six segments, which in the lower part of FIG. 5 too is recognizable, and the main cutting edges 2 then separate several Roundwood chips. The spacing of the cutting edges 4 result in the length L of the chips.

FIGS. 6 and 7 show schematically how the knives 1 manufactured by means of the device according to the invention or can be sharpened. 6 sharpen or several rotating, rotationally symmetrical, frustoconical grinding tools 5 whose Axes of rotation are perpendicular to the free surface 3, in one single work step both the main cutting edge 2 and the cutting edges 4. Due to at least one chamfer 6 the grinding tool 5 has at least two angles mutually arranged grinding surfaces 9 and 10. The Chamfer 6 defines the tip angle 7 of the cutting edges 4. Due to the parallel to the cutting edge flanks running feed direction increases the height of the Cutting blades 4 with increasing distance from the Main cutting edge 2 on.

As shown, the knife 1 becomes the free surface 3 ground along. In this way, both the The main cutting edge 2 and the cutting edges 4 are ground or sharpened. The cutting edges 4 go from the Main cutting edge 2 out and rise backwards. Since it is with the cutting edges 4 um from the free area 3 elaborated elements, they do not survive the contour of the knife 1 out.

7 shows a further embodiment of a Grinding tool 8, namely a grinding wheel, the Rotation axis horizontal to the free surface 3 of the knife 1 stands and has a chamfer 6 on each side. This Grinding tool 8 is on two opposite sides frustoconical.

The two grinding methods are only examples. Naturally the knives 1 with their cutting edges 4 can also be used other grinding methods or bodies are produced.

The invention enables, on the one hand, before the first use in a cutting machine from the open space 3 existing Standard cutting blades 4 grinding technology to work out, on the other hand a multiple resharpening both the main cutting edges 2 and the cutting edges 4 of blunt knives after a few hours Labor.

Because the cutting blades 4 directly from the main knife are ground, do not have to be intended as disposable knives Cutting blades are inserted, cutting bodies still need molded onto the knife. Furthermore, the Cutting edges 4 automatically with every sharpening process sharpened. A use of sharpened knives with blunt Cutting is not possible, which is process security guaranteed. Also the high acquisition costs for the Cutting 4 and the cost of the time consuming There is no need to change the blades.

In principle, the knife 1 according to the invention can be used in any Cutting process can be used. An example is that Use as a paring knife for making Veneer strips. Here a tree trunk rotates on one standing knife 1 over and turns every revolution the desired veneer thickness is delivered. A peeling with these knives 1 would thus produce veneer strips. A there is another possible application Plastics processing. With the knife 1 described to process plate-shaped workpieces into granules. The plate-shaped workpieces could thus in one Operation can be divided into two dimensions. A Another application would be as a replacement for comb knives in cutting machines.

Claims (11)

Two-dimensionally effective knife for cutting machines, in particular for wood-cutting machines, characterized in that the knife (1) has a main cutting edge (2) and at least one separating cutting edge (4), the knife (1) and the cutting edges (2, 4) being made in one piece , Knife according to claim 1, characterized in that the cutting edge (4), starting from the front edge of the main cutting edge (2), rises towards the rear. Knife according to claim 1 or 2, characterized in that the cutting edge (4) is machined out of the free surface (3) of the knife (1). Knife according to one of the preceding claims, characterized in that the cutting edge (4) does not protrude beyond the top of the knife (1). Knife according to one of the preceding claims, characterized in that the cutting edge (4) does not protrude beyond the underside of the knife (1). Device for producing and resharpening two-dimensionally effective knives (1) for cutting machines, in particular for wood-cutting machines, with at least one grinding tool (5, 8), characterized in that the grinding tool (5, 8) has at least two grinding surfaces (9, 10) arranged at an angle to one another ) having. Apparatus according to claim 6, characterized in that the grinding tool (5, 8) is rotationally symmetrical. Device according to one of the preceding claims, characterized in that the grinding tool (5, 8) is frustoconical at least on one side. Device according to one of the preceding claims, characterized in that the grinding tool (5, 8) is a grinding wheel. Method for producing and resharpening two-dimensionally effective knives (1) for cutting machines, in particular for wood-cutting machines, characterized in that a grinding tool (5, 8) is guided over the knife (1) and has at least two grinding surfaces (9, 10) arranged at an angle to one another ) having. A method according to claim 10, characterized in that the knives (1) remain in the cutting machine during sharpening.

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