EP0497233B1 - Apparatus for cutting thin planks from squared timber - Google Patents

Abstract

In an apparatus for cutting thin planks (22) from squared timber (6) which is moved on a guide face (4) against the cutting edge (16) of a knife (14), the adjustment of the distance between the guide face (4) and the plane (24) parallel to the latter and running through the knife cutting edge (16), and hence the setting of the apparatus to different plank thicknesses to be produced is performed by relative adjustment of the knife cutting edge (16) with respect to the guide face (4) in an inclined plane (36) forming an acute adjustment angle ( alpha ) with a normal (32) to the guide face (4). As a result of this arrangement, the distance between the knife cutting edge (16) and a counterpressure edge (30) is automatically adapted in the cutting direction if the plank-thickness setting of the apparatus is altered. Furthermore, in a preferred embodiment it is possible with this one adjustment also for the width of the discharge channel (between the faces 26 and 50) for the cut plank (22) to be simultaneously set to the new thickness. <IMAGE>

Description

The invention relates to a device for cutting a thin board from a squared timber according to the preamble of claim 1.

An arrangement of this type is described, for example, in DE-A-39 26 396, to which reference is expressly made in this connection.

The guide surface against which a squared timber to be processed is pressed while it is driven in its longitudinal direction as the conveying direction against the downstream knife can in principle be arranged in any orientation. However, it has proven to be expedient to arrange the guide surface horizontally so that the squared timber rests on it while it is being pushed against the knife.

A knife must necessarily have a finite wedge angle starting from the knife edge, which is why a board that has been cut from a squared timber cannot also be pulled off in the direction of the feed movement of the squared timber, but must be discharged laterally according to the wedge angle of the knife. The knife can now be arranged in the device so that its substantially smooth knife back runs parallel to the guide surface at a distance and forms a further support for the squared timber reduced in thickness by the cut board, the wedge surface of the knife then serving as a discharge surface for the detached board serves. In the spirit of this Description is the acute angle at which the wedge-shaped deflection surface of the knife runs to the back of the knife or to the guide surface, referred to as the deflection angle. The installation of the knife can in principle also be reversed, so that the wedge surface of the knife runs parallel to the guide surface and forms a further support for the squared timber, which is reduced in thickness, and the back of the knife serves as a discharge surface. With such an arrangement, however, in general, in continuation of the wedge surface of the knife, a support surface lying in the same plane for the reduced squared timber is to be provided on the knife carrier, so that the squared timber is sufficiently supported in its further advancing movement behind the knife.

On the side of the squared timber opposite the knife, devices of the type concerned here have a pressure device with which the squared timber is pressed against the guide surface and the knife, and feed means are also provided, with the aid of which the squared timber is driven against the knife in the conveying direction. These parts of a generic device not directly affected by the present invention are known and assumed to be familiar to the person skilled in the art.

In this regard, reference is made, for example, to DE-A-40 38 486.

The pressure edge arranged at the end of the guide surface and upstream of the knife, which generally rises somewhat above the guide surface, serves to exert an additional counterpressure on the squared timber, which is an uncontrolled one The knife should prevent the board from splitting off. Since the squared timber is generally pressed against the guide surface and the back of the knife, the protruding pressure edge is pressed somewhat into the timber. However, since this indentation essentially regresses after the board has been cut off due to the at least partially elastic properties of the wood, the thickness of the board is essentially determined by the distance between the guide surface and the plane parallel to the guide surface running through the knife edge.

The thickness of a board to be separated is preselected by changing the distance between the guide surface and the plane containing the knife edge in such a way that, for example, in a machine with a horizontally running guide surface, either a support table carrying the guide surface or the knife carrier in a direction perpendicular to Guide surface is adjusted relative to the stationary machine frame. When the guide surface is arranged horizontally, this is a pure height adjustment of one of these two machine assemblies.

To simplify the description, a machine is assumed below which has a support table with a horizontal guide surface for the squared timber.

The pressure edge upstream of the guide surface is, as already mentioned, upstream of the knife edge. This means that the vertical projection of the knife edge onto the elongated guide surface has a certain effect has a horizontal distance from the printing edge. In order to maintain optimal and constant cutting conditions, this horizontal distance must be changed depending on the thickness of the boards to be produced in such a way that it increases with increasing board thickness so that the board being separated can be transferred with sufficient bending radius in its direction of discharge. On the other hand, the printing edge should be as close as possible to the knife in order to avoid the already mentioned splitting effect. When changing the thickness setting, it is therefore also necessary to change the horizontal distance between the knife edge and the printing edge. Finally, when the thickness setting is changed, it may also be necessary to also change the elevation of the pressure edge above the guide surface, so that a total of three adjustment paths on the machine may be necessary in order to set this up to a changed board thickness.

Since the cutting edge of devices of the type in question is generally at an acute angle to the direction of conveyance of the wood, the board which is separated in each case also undergoes a twist when it is removed laterally along the discharge surface. It has been found that additional straightening devices for reversing this twisting can generally be dispensed with if the deflecting surface behind the pressure edge at a distance of the board thickness is compared with a supporting surface which, together with the deflecting surface, forms a channel for discharging the separated board, which at least has a certain amount Distance behind the knife edge or the printing edge. Since the discharge channel runs at an angle to the guide surface, the machine is set to a different board thickness by adjusting the height For example, the guide surface does not transfer the change in height in absolute size to the distance between the discharge surface and the support surface, so that when the machine is set up to a different thickness, the discharge channel for the separated board must also be adjusted by changing the distance of the support surface from the discharge surface. This would be a fourth adjustment, which is required when changing the board thickness in known machines.

The invention has for its object to improve a device of the type described in such a way that when changing the board thickness setting as few adjustment paths are required on the device.

This object is generally achieved by the characterizing features of patent claim 1.

It has been found that the horizontal distance between the knife edge and the printing edge has to be changed essentially proportionally with the board thickness setting. This horizontal distance between the knife edge and the printing edge should be in the range between about 0.05 and 0.2 times the board thickness. Preferred distances are between 0.1 times and 0.15 times the board thickness. If a constant factor is used in this respect, it can be achieved by an inclined adjustment according to the invention that when the board thickness setting of the device is changed, the distance between the knife edge and the printing edge is automatically adjusted accordingly. This results in adjustment angles in the range between approximately 3 and 15 degrees, preferably between 5 and 12 degrees.

Since the wedge angle of a conventional knife is about 20 degrees, and this wedge angle forms the discharge angle of the separated board, a separate setting of the discharge channel between the discharge surface and the support surface can be avoided if the adjustment angle corresponds to approximately half the discharge angle, which is the case with a knife wedge angle of 20 ° corresponds to an angle of 10 °, which falls within the preferred range for the adjustment angle. In this case, namely, the direction of adjustment runs along the bisector of the obtuse angle between the support surface and the discharge surface. An adjustment in this direction has the effect that the vertical distance between the guide surface and the knife edge plane is changed in the same absolute amount as the distance between the discharge surface and the support surface of the discharge channel. A separate adjustment of the width of the discharge channel can thus be omitted.

In this way, three different adjustment paths required for the board thickness adjustment of the device can be combined in a single machine adjustment. Only the board of directors of the printing edge above the guide surface needs a separate adjustment if necessary. In a preferred embodiment, however, this can be done very simply by mounting the pressure edge on a wedge element extending in its longitudinal direction, so that a relative longitudinal displacement between the pressure edge and this wedge element leads to a change in the height of the pressure edge. This adjustment can be done by a simple lateral spindle drive or an actuating cylinder, since at a correspondingly flat angle Wedge element relatively large adjustment only cause a small change in height of the printing edge.

The inclined adjustment according to the invention between the knife and the guide surface can take place both by an adjustment of the support table carrying the guide surface and by a corresponding adjustment of the knife carrier.

Fig. 1

eine Anordnung für eine Vorrichtung zum schneidenden Abtrennen eines dünnen Brettes von einem Kantholz, bei der der die Kantholzführungsfläche aufweisende Stütztisch in schräger Richtung höhenverstellbar ist,

Fig. 2

eine entsprechende Anordnung, bei der der Messerträger in schräger Richtung höhenversteilbar ist, und

Fig. 3

eine Schnittansicht der Höhenverstellbarkeit der Druckkante.

The geometric relationships are explained in more detail below with reference to the attached drawings, which relate to the area of the device concerned here.

Fig. 1

an arrangement for a device for cutting a thin board from a squared timber, in which the support table having the squared timber guide surface is height-adjustable in an oblique direction,

Fig. 2

a corresponding arrangement in which the knife carrier is height-adjustable in an oblique direction, and

Fig. 3

a sectional view of the height adjustability of the printing edge.

The section shown in FIG. 1 from a device for cutting a thin board from a square timber shows a support table construction 2 of the device, which is provided on its upper side with a horizontal guide surface 4 for a square timber 6. The support table construction 2 is shown broken off along the line 8 below, where a (not shown in detail) fixed machine frame connects.

As a further assembly, the device has a knife carrier construction 10, which is shown broken off along the line 12 and is likewise connected here to the most stationary machine frame (not shown).

A knife 14 with a knife edge 16 and a knife back 18 rests on the knife carrier construction 10 in a horizontal arrangement. The squared timber 6 is pressed against the guide surface 4 and the knife back 18 by means of pressure means (not shown) and in one conveying direction by means of feed means (not shown). which is indicated by the arrow 20, moved against the knife edge 16, a board 22 being separated from the squared timber 6.

If one assumes in the drawing that the knife edge 16 in the device part shown essentially schematically in section runs perpendicular to the drawing plane of FIG. 1, the conveying direction 20 does not extend in the drawing plane, but in the horizontal direction at an acute angle to Plane level, since the knife edge 16 in turn forms an acute angle with the conveying direction 20 in the device. For the sake of simplicity, however, the squared timber 6 has been shown as if it were moving to the right along the arrow 20 in the plane of the drawing.

It can be seen that the squared timber 6 rests on the guide surface 4 before the board 22 is cut off, while the squared timber reduced in thickness by the thickness of the board 22 continues on the back 18 of the knife 14. The knife edge 16 lies in a plane parallel to the guide surface 4 24, whose vertical distance from the guide surface 4 corresponds to the thickness of the board 22 between its main surfaces. Starting from its cutting edge 16, the knife weeps between its back 18 and a wedge surface 25 a knife angle β, which in the exemplary embodiment is 20 °. The wedge surface 26 is at the same time a deflecting surface for the separated board 22, which is thus discharged obliquely downwards at a diverting angle to the guide surface 4, which corresponds to the knife angle β.

A component 28 is connected to the support table construction 2 on its side facing the knife 14, which is provided on its upper side with a pressure edge 30 which generally protrudes somewhat upwards over the guide surface 4 and thus presses into the squared timber 6. Assuming that the knife edge 16 runs perpendicular to the plane of the drawing, the printing edge also runs perpendicular to the plane of the drawing and parallel to the knife edge 16. In the drawing, the line 32 runs as normal to the guide surface 4 through the knife edge 16, while the perpendicular line parallel thereto 34 runs through the printing edge 30. The distance s between the lines 32 and 34 is thus the distance between the knife edge 16 and the pressure edge 30 in the horizontal direction. A line 36 is also shown, which extends at an angle α to the normal 32 on the guide surface 4. This line 36 belongs to a plane that runs through the knife edge 16 and the pressure edge 30 in the exemplary embodiment.

The support table structure 2 is provided with height adjustment means 38, only shown schematically, with which a movable part 40 of the Support table construction together with the guide surface 4 and the pressure edge 30 can be adjusted along a plane 44 relative to a part 42 of the support table construction which is fixed to the frame. This plane 44 runs parallel to the plane which contains the line 36, which thus forms an adjustment plane in which the pressure edge 30 can be changed at an angle α as the adjustment angle and with it the guide surface 4 for adjusting the board thickness of the machine in its height.

If the board thickness setting is reduced to zero, the guide surface 4 and the pressure edge 30 are raised to such an extent that the pressure edge is located on the knife edge 16. If the pressure edge 30 is lowered along the line 36 inclined by the angle α in this embodiment, the horizontal distance between the knife edge 16 and the pressure edge 30 increases in proportion to the increasing board thickness distance between the plane 24 and the guide surface 4.

It is not absolutely necessary that the adjustment plane 36 running through the pressure edge 30 also runs through the knife edge 16, so that the pressure edge 30 and the knife edge 16 coincide approximately when adjusted to the same height, the adjustment plane 36 can rather also be placed so that it does not run through the knife edge 16, so that when the pressure edge 30 is raised to the level of the knife edge 16 there is still a certain horizontal distance s between the knife edge and the pressure edge. The particular choice of the adjustment angle α and the position of the adjustment plane 36 is left to the choice of the person skilled in the art.

In the illustration in FIG. 1, to the right of the component 28 having the pressure edge 30, there is still a component 48 which is provided on its upper side with an oblique support surface 50 which runs parallel to the discharge surface 26 and together with this discharge duct for the separated one Board 22 forms. If the adjustment angle α is chosen such that it is half the discharge angle β, the line 36 forms the bisector of the obtuse angle between the guide surface 4 and the support surface 50. Under this condition, an adjustment of the pressure edge 30 along the adjustment plane 36 leads to the same Distance changes between the plane 24 and the guide surface 4 on the one hand and the discharge surface 26 and the support surface 50 on the other hand, so that the thickness of the discharge channel for the separated board 22 is automatically adapted to the cut board thickness. In practice, certain deviations from the exact geometric compliance with these conditions may be permissible. In the exemplary embodiment, the adjustment angle is approximately 7-8 °.

A wedge element 52 is also arranged under the component 28, which carries the pressure edge 30. A view perpendicular to the plane of the drawing in FIG. 1 is shown in FIG. 3. At the ends of the wedge element 52 extending in the direction of the pressure edge 30, adjusting screws 54 are provided with which the wedge element 52 can be displaced in its longitudinal direction, thereby causing a slight height adjustment of the pressure edge 30. The spindles or set screws 54 could, for example, also be replaced by a hydraulic actuating cylinder acting on the wedge element 52. in the 3 are still indicated elongated screw connections 56, which have to be loosened for the height adjustment of the component 28 and tightened again after its adjustment in order to firmly lock the component 28 with the pressure edge 30 on the support table construction 2. With corresponding positive guides, eg dovetail guides, these screw connections could also be omitted.

From the above illustration it follows that the device for cutting boards from a single machine adjustment by means of the height adjustment means 38 can be adjusted to practically all conditions of a changed board thickness. A relative adjustment of the pressure edge 30 with respect to the guide surface 4 is not necessary in every case and can, if necessary, be carried out in a simple manner by moving the wedge element 52.

The arrangement of FIG. 2 differs from that of FIG. 1 only in that instead of the height adjustment means 38 in the support table construction 2 corresponding height adjustment means 58 are provided with an inclined plane 60, with the aid of which the knife 14 can now be adjusted in height along the adjustment plane 36 , Here the adjustment plane runs through the knife edge 16, but does not necessarily have to run through the pressure edge 30. The conditions are otherwise the same as in the embodiment in FIG. 1.

Both in FIG. 1 and in FIG. 2, a guide plate 62 is also provided on the knife support structure 10 for guiding the separated board 22.

Claims (9)

1. A device for cutting separation of a thin board from squared timber, comprising:

   - a guide surface (4), along which the squared timber can be fed in its longitudinal direction as conveying direction,

   - a cutting blade (14) arranged downstream of the guide surface (4) when viewed in the conveying direction, the cutting edge (16) of which cutting blade (14) is arranged at an angle to the conveying direction in a plane (24) which runs in parallel with the guide surface (4) at an adjustable distance corresponding substantially to the thickness of the board to be separated,

   - a pressure edge (30) running parallel to the cutting edge (16) and to the guide surface (4) and arranged at the end of the guide surface (4) facing the cutting edge (16), which pressure edge (30) projects if necessary slightly out of the plane of the guide surface (4), and

   - adjusting means for altering this distance between the guide surface (4) and this parallel plane (24) containing the cutting edge,

   characterised in that the adjusting means (38,58) effect a parallel displacement of the cutting edge (16) or the pressure edge (30) in an adjusting plane (36) which forms an acute angle of adjustment (α) with a line (32) normal to the guide surface (4), the adjusting plane (36) being so oriented that, upon an increase in this adjustable distance between the cutting edge (16) and the guide surface (4), the distance between the cutting edge (16) and the pressure edge (30), projected onto the plane of the guide surface (4), increases.
2. A device according to claim 1, characterised in that the adjusting plane (36) is a plane running parallel with that plane which contains the cutting edge (16) and the pressure edge (30), or in that the adjusting plane (36) itself substantially contains the cutting edge (16) and the pressure edge (30).
3. A device to claim 1 or claim 2, characterised in that the angle of adjustment (α) lies in the range of from 3° to 15°.
4. A device according to claim 3, characterised in that the angle of adjustment (α) lies in the range of from 5° to 12°.
5. A device according to claim 1 or claim 2, comprising a diverting surface (26), starting from the cutting edge (16), for diverting a separated board (22), which diverting surface (26) forms an acute angle of divertion (β) with the plane running through the cutting edge (16) and parallel with the guide surface (4), wherein a supporting surface (50) is provided which is arranged downstream of the pressure egde (30) when viewed in the conveying direction, which runs substantially parallel to the diverting surface (26) and which forms, together with the diverting surface (26), a channel for the diversion of a separated board (22), the distance between diverting surface (26) and supporting surface (50) is substantially equal to or slightly greater than the distance between the guide surface (4) and the plane (24) running through the cutting edge (16) and parallel to the guide surface (4), and the angle of adjustment (α) corresponds approximately to half the angle of diversion (β).
6. A device according to at least one of claims 1 to 5, characterised in that the guide surface (4) is adjustable relative to the cutting blade (14) fixed to the frame.
7. A device according to at least one of claims 1 to 5, characterised in that the cutting blade (14) is adjustable relative to the guide surface (4) fixed to the frame.
8. A device according to at least one of claims 1 to 7, characterised in that the pressure edge (30) is height-adjustable relative to the guide surface (4).
9. A device according to claim 8, characterised in that the pressure edge (30) is mounted on a wedge member (52) extending in the longitudinal direction thereof and is height-adjustable by a relative longitudinal displacement between the pressure edge (30) and the wedge member (52).

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