EP0988946A2 - Method and device for chipping wood - Google Patents

Abstract

The method and appliance for machining wood incorporate a ring (2) fitted with cutting blades (5) on its inner periphery and parallel with its rotational axis (3). The wooden trunks (1) are held at one end by a holder and insertion system and are inserted into the ring by means of the opposite, free end. A forward thrust mechanism consists of a swivel part swiveling on a circular track (11) and on which the rotary bladed ring is positioned. The swivel axis (13) belonging to the part, and the rotational axis of the bladed ring are parallel. The wood trunks are held between two circle-arc shaped side walls (6,7).

Description

The invention relates to a method for cutting logs large-scale wood chips, in which a rotating, with parallel to its axis of rotation aligned cutting knives provided knife ring on the one hand and a number also aligned parallel to the axis of rotation of the knife ring On the other hand, logs move towards each other and the logs are cut become. The invention also relates to an apparatus for executing this procedure.

Methods and devices for cutting wood are state of the art known for a long time. With the development of wood materials, such as Chipboard, fiberboard, chipboard beams, chipboard molded parts, etc. Such technologies have gained in importance and are constantly being perfected been.

Oriented Strand Board" (OSB), eine Weiterentwicklung der herkömmlichen Spanplatte. Unter dem Begriff Strands" sind in diesem Zusammenhang großflächige Holzspäne mit bevorzugter Geometrie' beispielhaft 100 mm x14 mm x 0,5 mm, zu verstehen, die flächig kreuzweise übereinandergeschichtet zu OSB verleimt werden. Die so entstehenden Platten zeichnen sich gegenüber herkömmlichen Spanplatten durch wesentlich höhere Festigkeit aus. Sie weisen außerdem aufgrund der Lageorientierung der Holzspäne einen bedeutend geringeren Anteil Klebstoff bzw. ein günstigeres Verhältnis der Bestandteile Holz und Klebstoff auf, was zu einer Einsparung von Klebstoffen führt. This is one of the most recently developed wood-based materials

Oriented Strand Board "(OSB), a further development of conventional chipboard. Under the term Strands "are to be understood in this context as large wood chips with preferred geometry ', for example 100 mm x14 mm x 0.5 mm, which are glued together cross-laminated on top of each other to form OSB. The boards produced in this way are distinguished from conventional chipboards by their significantly higher strength. Due to the orientation of the wood chips, they also have a significantly lower proportion of adhesive or a more favorable ratio of the wood and adhesive components, which leads to a saving in adhesives.

However, with the development of the OSB, there are also quality requirements the wood chips increased, because the advantages mentioned are only with compliance the chip geometry, especially the chip thickness.

The corresponding processes and facilities for wood cutting are therefore discussed The primary requirement was to deliver chips of defined quality. This effort for chip quality has recently led to the development of cutting machines for logs and residual wood, for example for pieces that have not been cut to length Round wood, guided, in which the machining with a rotating knife ring is made. This knife ring essentially has the geometry of a Hollow cylinder on, radially symmetrically distributed parallel over its inner circumference cutting knives aligned with the axis of rotation are arranged.

In sections, a bundle of parallel to the Wood logs aligned with the axis of rotation, each by one Length dimension, which corresponds to the dimension of the knives in the axial direction; there the knives are not yet in contact with the logs. After the logs have been pushed in, they are clamped by a holding system and then the rotating knife ring in the radial direction on the in his Interior, the so-called machining chamber, protruding section of the Logs moved too, consequently the knives in contact with the logs come and the machining takes place, which is characterized by the peeling effect, which the rotating knives aligned parallel to the longitudinal direction of the logs cause the required chip quality.

Of course, play in the chip formation process with regard to the chip quality Feed speed, knife board, division of the knife ring or Number of knives on the circumference, cutting speed, radius of the flight circle Cutting etc. play an essential role. Extensive investigations are already underway done, the results are known and are already being used. Indeed is another key criterion in the manufacture of strands yet not sufficiently solved, namely the amount that can be achieved with a knife ring revolution Chips of the same quality, especially the same chip thickness.

If one looks at the movement curves of the cutting knives, it follows that each During the cutting process, the cutting edge describes a path that is spiral runs and corresponds to a helix with a slope that of the Feed direction and depends on the feed speed.

With respect to the feed motion of the Horizontalzerspanung and Vertikalzerspanung are known in principle, whereby the designations indicate horizontal and vertical to the feed direction of the knife ring. In the patent DE 35 05 077 C2, for example, a machine for horizontal machining is shown, in which the bundle of wood is placed on a horizontally arranged sliding wall, is slid over this sliding wall with the aid of a feed slide into the interior of the knife ring and is held in this position with clamping elements. Then the feed movement of the rotating knife ring takes place in the horizontal direction, for example from left to right, the wood bundle being machined. The depth of the machining chamber is determined by the axial length of the individual knives.

In the case of vertically machining machines, the basic difference is in Compared to the horizontal chipper essentially in the vertical direction Feed movement of the knife ring. Here, too, first of all with the help of a Feeder a bundle of logs into the inside of the knife ring advanced, again by a distance equal to the axial length of the knife corresponds. Then the rotating knife ring is in a vertical feed movement offset, whereby the machining takes place. So is from the patent DE 43 35th 348 C1 a long wood chipper is known in which the feed movement is vertical, and is directed upwards against the bundle of wood. The execution is analogous to this of cutting devices with vertical downward movement of the knife ring conceivable.

The linear feed movement is characteristic of both arrangements described. The machining process taking place will be briefly explained below. 1 shows the basic representation of a knife ring with m _G = 36 knives. Of these knives, theoretically only the m _E = 18 knives can be engaged, which are arranged on the semicircle in the feed direction. If a vertical upward feed movement, as shown in FIG. 1, is now assumed, then depending on their current position on the circumference of the knife ring, different feed paths result which have different chip thicknesses, depending on their current position.

1 shows a cutting edge A and the cutting edge B lagging the cutting edge A for different phase angles α during the rotation of the knife ring. It can be seen that the greatest chip thickness results at d ₃ and the smallest chip thickness at d ₁ . The resulting chip thicknesses therefore depend on the respective position of a cutting knife on the circumference of the knife ring at which the intervention takes place.

To be a benchmark for the quality of the chips supplied To find the positions of the cutting knives, you divide the circumference of the knife ring in sectors from which chips are supplied, the thicknesses of which are within a permissible tolerance limit.

In FIG. 2, the knife ring for a vertical chipper with upward machining is divided into individual phase sectors, the sectors extending in the feed direction and the division being based on the number of knives. Since of the total number of m _G = 36 knives theoretically only m _E = 18 knives can be engaged and these 18 knives are distributed symmetrically to the axis of rotation, there are a number of nine sectors S ₁ to S ₉ . It is assumed that chips with a thickness that lie within a permissible tolerance range are generated within each sector.

It follows from this that chips of a sufficiently uniform thickness can only be obtained if the wood bundle is only kept in one of the sectors during the cutting process, possibly in two or three neighboring sectors, for example sectors S ₁ and S ₂ . At the same time, however, it is clear that the cost-effectiveness of a cutting device, particularly in connection with the production of OSB, depends to a large extent on how many chips of uniform thickness are produced with one revolution of the knife ring. In the diagram according to FIG. 3, the areas shown above each sector S ₁ to S ₉ are a measure of the chip quantities occurring in this sector. From this it can be seen that only the chips from the sectors S ₁ and S ₂ , depending on the sharpness of the quality requirement, can possibly also be used from the sector S ₃ . This also reveals the disadvantage inherent in the prior art, namely that the amount of chips of sufficient quality that can be generated per unit of time is very small.

From this, the invention is based on the object of a method for Machining logs of the type described above in such a way that with each revolution of the knife wheel, a larger number of chips that the above-described quality requirements are sufficient, can be produced.

According to the invention this is achieved in that the directed towards the logs Movement of the knife ring and / or the movement directed at the knife ring the logs at least during the machining process on one curved path takes place.

With the relative movement running on a curved path between the knife ring and the bundle of the logs to be cut, it is achieved that some of the chip sectors compressed ", others The surfaces above the chip sectors (see FIG. 3) are no longer distributed symmetrically to the axis of rotation, but are shifted asymmetrically so that a larger proportion of chips with a quality within the specified tolerance results.

A particularly preferred embodiment of the invention results for a method variant, where the knife ring is moved on a circular path while the logs are kept in relative rest to the knife ring.

It can advantageously be provided that the logs between the side walls are held, like the movement of the knife ring a circular arc curvature have, the path of movement of the knife ring and the Curvatures of the side walls have the same center.

An embodiment of the invention in which the logs are very particularly preferred initially held at one end and with the opposite free end in one on its inner circumference with axially parallel cutting knives equipped rotating knife ring and then the knife ring is moved perpendicular to its axis of rotation on a circular path, the Machining takes place inside the knife ring.

The invention also achieves the object of a device for machining Logs with a rotating knife ring on its inner circumference is equipped with cutting blades aligned parallel to its axis of rotation, with an insertion and holding system for logs through which the logs held at one end and with the opposite free end in the Knife ring are insertable and with a feed device for generating a movement of the rotating towards the free ends of the logs To further develop the knife ring in such a way that with each revolution of the knife wheel produced amount of chips with a chip thickness within a tolerance limit is larger than in the prior art.

This is achieved according to the invention by the feed device on one Circular path has pivotable part on which the rotating knife ring is arranged , the pivot axis assigned to the part and the axis of rotation of the knife ring are aligned parallel to each other.

On the swiveling part, for example a seesaw, on which the knife ring is arranged, the drive motor for the knife ring and the transmission members can arranged for the rotary movement of the drive motor to the knife ring his. This results in advantageous constructive aspects, since the Drive motor also used as a counterweight to the mass of the knife ring and Can be mounted on the opposite side of the swivel axis For generation a hydraulic drive can be provided for the pivoting movement, for example a hydraulic cylinder that is connected to the swivel lever that when extending the piston rod, the knife ring against the one to be machined Bundle of wood is advanced.

It is also advantageous if the logs between two side walls are held, which have an arcuate curvature, the centers of curvature of the two side walls in the swivel axis of the knife ring lie and the radius of curvature of a first side wall smaller and the Radius of curvature of the second side wall is greater than the pivot radius of the Knife ring are executed. This ensures that during the feed movement the axis of rotation of the knife ring at a constant distance moved to both side walls between the side walls.

In addition, the radii of curvature can be measured so that the distances between the circular path of the axis of rotation of the knife ring and the inner and the outer side wall is not the same size, but for example the distance between Axis of rotation and outer side wall, i.e. the side wall with the larger one Radius of curvature is greater than the distance between the axis of rotation and the inner side wall, i.e. to the side wall with the smaller radius of curvature. This advantageously results in a shift of the chip sectors and thus a further increase in the amount of chips with sufficient quality.

In this connection there is a special feature within the scope of the invention in that the side walls are designed in such a way that they project into the knife ring approximately according to the axial extension of the knife and are fixed to the knife ring. When operating the invention Follow the device that is designed according to this variant the sidewalls of movement of the knife ring, being relative to the Moving logs. This has the particular advantage that the due the periodic feed movement of increasingly shorter logs still held securely even with short lengths within the machining chamber become.

Furthermore, the invention can be designed in such a way that the knife ring not on a rocker or a swivel lever, but on a guide carriage is mounted, which is on a curved path, preferably also a circular path, is slidably arranged. The drive motor for the knife ring can also be used here also be mounted on the guide carriage and it is also here advantageous to use a hydraulic cylinder to generate the feed movement, on the one hand fixed to the frame and on the other hand with the guide carriage is connected and the guide carriage when extending the piston rod moved and thus triggers the feed movement.

In an analog design variant it can further be provided that the Knife ring with a gear member of a four-link coupling gear, for example a push crank chain, connected and movable on a circular path is. In this case too, it is advantageous to trigger the movement of the Coupling gear or the feed movement of the knife ring the coupling gear to connect with a hydraulic drive.

A very advantageous embodiment of the invention can be achieved if the Radius of curvature of the feed movement in a range between 1800mm and 2500mm.

Conceivable and within the scope of the described invention are self-evident also arrangements in which a feed movement of the knife ring on an irregularly curved cam track, for example a parabola, he follows.

Fig.1

den Eingriff der Schneiden während der Rotation des Messerringes

Fig.2

ein Beispiel für die Einteilung des Messerringes in Spansektoren

Fig.3

ein Beispiel für die Verteilung der Spandicke über die Spansektoren nach dem Stand der Technik

Fig.4

die Prinzipdarstellung einer erfindungsgemäßen Anordnung

Fig.5

ein Diagramm mit der Verteilung der Spandicken über die Spansektoren bei Anwendung des erfindungsgemäßen Verfahrens

The invention will be explained in more detail below using an exemplary embodiment. Show in the accompanying drawings

Fig. 1

the engagement of the cutting edges during the rotation of the knife ring

Fig. 2

an example of the division of the knife ring into chip sectors

Fig. 3

an example of the distribution of the chip thickness over the chip sectors according to the prior art

Fig. 4

the schematic diagram of an arrangement according to the invention

Fig. 5

a diagram with the distribution of the chip thicknesses over the chip sectors when using the inventive method

In Figure 4, a device for machining logs 1 is shown in the a knife ring 2 is rotatably mounted about an axis of rotation 3. In the illustration 4, the axis of rotation 3 runs perpendicular to the plane of the drawing, the logs 1 are aligned with their longitudinal direction parallel to the axis of rotation 3.

The knife ring 1 has the geometric shape of a hollow cylinder, which on its inner circumference 4 is equipped with cutting knives 5. The cutting knives 5 are distributed radially symmetrically on the inner circumference 4 of the knife ring 2, i.e. she have the same arc distance from each other. 4 are exemplary twenty cutting blades 5 are provided.

Furthermore, the device comprises an insertion and holding system for the logs 1, wherein essentially a first to implement the holding function Side wall 6, a second side wall 7, a base 8 and a counter wall 9 are provided. On the base 8, the logs 1 are stored, and so that they in their longitudinal direction or in the direction of the axis of rotation 3 the base 8 are slidable. The deposited on the base 8 and by the two side walls 6 and 7 wooden trunks 1 held sideways are piled up into a bundle. Laying down the logs 1 the base 8 for the purpose of loading the device takes place outside the knife ring 2.

After loading the device or after placing the logs on the base 8 between the side walls 6 and 7 is made by the slide-in system, which is not shown in the drawing, the advancement of the Logs 1 (perpendicular to the drawing plane) in the interior of the knife ring 2, i.e. into the machining chamber 10. For this, the logs are 1 um a length dimension inserted into the knife ring 2, that of the length of the cutting knife 5 corresponds in the axial direction.

The machining process is now initiated by the knife ring 2 in Rotation offset about the axis of rotation 3 and then on the in the machining chamber 10 logs 1 in relative rest to the knife ring 2 is moved to. The cutting process starts when the rotating Cutting knife 5 with the logs 1 closest to the circumference 4 come to the intervention. The feed forces that occur are from the side walls 6 and 7, but especially taken from the counter wall 9.

In order to achieve that during the machining process one as possible large amount of wood chips of the same quality or with one within one predefined tolerance range lying chip thickness is according to the invention provided that the feed movement of the knife ring 2 on a Curve takes place. The path movement, the axis of rotation 3 of the knife ring 2 describes, is identified by way of example as a circular path 11. According to Fig. 4 runs the circular path 11 in the plane of the drawing, i.e. the axis of rotation is 3 aligned perpendicular to the circular area enclosed by the circular path 11 becomes.

The movement of the axis of rotation 3 on the circular path 11 is according to the invention achieved by a rocker 12 which is supported and tiltable about a pivot axis 13 on which the knife ring 2 is rotatably mounted. Also arranged on the rocker 12 is the drive motor 14 which is used to generate the rotary movement of the Knife ring 2 is used and for this purpose via a belt drive 15 with the Knife ring 2 is connected.

In the illustrated embodiment, the pivoting movement of the knife ring takes place 2 counterclockwise, i.e. the weight of the logs 1 counteracts the feed forces. Deviating from this are also Embodiments are conceivable in which the pivoting movement of the knife ring 2 clockwise in the same direction, with the knife ring 2 moved towards the logs 1 in the direction of gravity and the logs 1 against the gravity and through the knife ring acting feed forces are to be maintained.

To generate the pivoting movement of the rocker 12 about the pivot axis 13 and thus to generate the feed movement of the knife ring 2 against the logs 1, a hydraulic cylinder 16 is provided. The hydraulic system with which the hydraulic cylinder 16 is connected, the drive motor 14 for the knife ring 2 as well as the drive mechanism for the slide-in and holding system are connected to a control direction that is not shown in the drawing is and which should not be described in more detail, since it is from the State of the art is already known. This control device is dependent from a sequence program in which the above-described movement sequences the triggering and coordination of the individual movements are stored, as inserting the log 1 into the machining chamber 10 by control the insertion system, switching on the rotation of the knife ring 2 by activation of the drive motor 14, initiation of the feed movement of the knife ring 2 by acting on the hydraulic cylinder 16, reversing the feed movement by counteracting the hydraulic cylinder 16, repeated insertion of the logs 1 into the machining chamber 10, etc.

The chips produced during the decomposition process fall under the force of gravity then into the hopper 17, from which it is transported to OSB for further processing become.

According to a preferred embodiment variant of the invention, the first Side wall 6 and the second side wall 7 are curved in a circular arc, the centers of curvature of both sidewalls, as well as the Center of curvature of the circular path 11, lie in the pivot axis 13. The The radius of curvature of the side wall 6 is smaller, the radius of curvature of the Side wall 7 is larger than the radius of curvature of the circular path 11, so that the circular path 11 runs between the two side walls 6 and 7. Through the The curvature of the side walls 6 and 7 following the circular path 11 is advantageous achieved that always the same during the entire machining process Chip sectors of the knife ring 2 remain in engagement with the logs 1.

Within the scope of the invention there are further design variants that are the first Side wall 6, the second side wall 7, the base 8 as well as the counter wall 9 concern. So it is conceivable to extend this towards to design the knife ring 2 differently, for example the side walls 6 and 7 as well as the sections of the logs to be machined 1 in the machining space 10 protrude and the feed movement of the knife ring 2 following can be arranged pivotable about the pivot axis 13, while the counter wall 9 remains fixed to the frame. This configuration has the advantage that the logs 1 within the knife ring 2 or in the machining chamber 10 one during the entire cutting process have a well-maintained grip, but requires relative movement between the side walls 6 and 7 and the counter wall 9 the relative movement between the side walls 6 and 7 and the logs 1 overcoming the investment forces, with which the logs 1 rest on the side walls 6 and 7 and thus higher feed forces.

In a similar way it can be provided that the base 8 in the machining space protruding and following the feed movement of the knife ring 2 is arranged movably.

When using the method according to the invention or the device proposed according to the invention and its variants when machining logs 1, the change in the chip diagram shown in FIG. 5 can be achieved. In FIG. 5 it can be seen that the chip quantities obtained from the individual chip sectors are no longer distributed symmetrically to the axis of rotation 3, as was the case in the prior art (see FIG. 3), but that one is here on the axis of rotation 3 related asymmetry is to be recorded, which means that, for example, a larger amount of chips from the neighboring chip sectors S ₁ , S ₂ and S _{3 are} available. In accordance with the object of the invention, a higher availability of chips of uniform quality is thus advantageously achieved. The width between the side walls 6, 7 and the area between the side walls 6, 7 that receives the logs can be aligned within the machining chamber 10 to the sectors that provide chips of sufficient quality and quantity.

An embodiment of the invention advantageous from these points of view Device results when the distance between pivot axis 13 and Rotation axis 3 is carried out with 2,200 mm and the angle β around which the axis of rotation 3 is pivotable, is about 50 °.

Here, as shown in Fig. 4, the straight line between the swivel axis 13 and axis of rotation 3 before the start of the machining process, i.e. while the supply of the logs 1 in the machining chamber, approximately horizontally be aligned and the feed or pivoting movement of the knife ring 2 about the pivot axis 13 should be in the R direction.

The diameter of the inner circumference 4 equipped with the cutting knives 5 the knife ring 2 can advantageously as the distance between the pivot axis 13th and axis of rotation 3 with 2,200 mm. The radius of curvature of the first side wall 6 should be 1,550 mm during the radius of curvature the second side wall 7 should be 3,050 mm. That is the distance between the circular path 11, on which the axis of rotation 3 moves, and the side wall 6 by an amount of 200 mm smaller than the distance between the circular path 11 and the side wall 7. Due to this asymmetry in the positioning of the both side walls in relation to the path of movement of the axis of rotation 3 results a further improvement in the availability of chips of uniform quality.

Claims (10)

Method for cutting wood, in which a rotating knife ring (2) provided with cutting knives (5) aligned parallel to its axis of rotation (3) on the one hand and a number of logs (1) also aligned parallel to the axis of rotation (3) of the knife ring (2) on the other hand, moving towards one another and the logs being machined, characterized in that the movement of the knife ring (2) directed at the logs (1) and / or the movement of the logs (1) directed at the knife ring (2) at least during the machining process run on a curved path. Method according to claim 1, characterized in that the knife ring (2) is moved on a circular path (11) while the logs (1) in relative Keep calm to the knife ring (2). A method according to claim 2, characterized in that the logs (1) held between side walls (6,7), which like the movement of the Knife ring (2) have a circular arc curvature, the path of movement the knife ring (2) and the curvatures of the side walls the same Have focus. Method according to one of the preceding claims, in which the logs (1) first held at one end and with the opposite free end in one on its inner circumference (4) with axially parallel Cutting knives (5) equipped rotating knife ring (2) are introduced and then the knife ring (2) perpendicular to its axis of rotation (3) on a Circular path (11) is moved, the machining in the interior of the knife ring (2) is done. Device for cutting logs (1), with a rotating knife ring (2), which is equipped on its inner circumference (4) with cutting knives (5) aligned parallel to its axis of rotation (3), with a holding and insertion system for the logs (1), by means of which the logs (1) are held at one end and can be inserted into the knife ring (2) with the opposite, free end and with a feed device for producing a movement of the rotating knife ring (2) directed towards the free ends of the logs (1), characterized in that the feed device has a part which can be pivoted on a circular path (11) and on which the rotating knife ring (2) is arranged the swivel axis (13) assigned to the part and the axis of rotation (3) of the knife ring (2) being aligned parallel to one another. Apparatus according to claim 5, characterized in that the logs (1) are held between two side walls (6,7), which is an arch of ice Have curvature, the centers of curvature of the two Side walls (6, 7) lie in the swivel axis (13) of the knife ring (2) and the radius of curvature of a first side wall (6) is smaller and the radius of curvature the second side wall (7) is larger than the swivel radius the knife ring (2). Device according to claim 6, characterized in that the radius of curvature the first side wall (6) about 1,550 mm, the swing radius of the knife ring about 2,200 mm, the radius of curvature of the second side wall (7) about 3,050 mm and the inner diameter of the knife ring (2) about 2,200 mm. Device according to claim 6 or 7, characterized in that the side walls (6,7) designed in sections protruding into the knife ring (2) and are fixed to the knife ring (2), whereby they move following the knife ring (2), movable relative to the logs (1) are. Device according to the preamble of claim 5, characterized in that the knife ring (2) on a curved path, preferably a circular path (11), slidably mounted part is arranged. Device according to the preamble of claim 5, characterized in that that the knife ring (2) with a gear link of a four-link Coupling gear, preferably a slider crank chain, firmly connected and with this is movable on a circular path (11).

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