EP0440151A2 - Method for flattening tree trunks - Google Patents

Abstract

A method serves for flattening logs (10) showing a curved longitudinal center line (10a). The logs (10) are conveyed in horizontal position in their longitudinal direction, with their convex side (11) up and their concave side (12) down. The concave side (11) of the logs (10) is flattened from below in the area of their butt ends (27). In order to optimize the yield in wood, the logs (10) are measured before carrying out the flattening step, in a position where they are supported on a reference plane (13) by the end points (20, 22) of their concave side (12) only. The geometrical position of a first point (26) of the log (10) is determined on the convex side (11) as its elevation above the reference plane (13). The butt end (27) of the log (10) is then lowered, while keeping the end point (20) opposite the butt end of the log constantly in contact with the reference plane ( 13), until the first point, which defines the lowest point between the said highest elevation (23) and the said butt end (27) on the said convex side (11), comes to lie at a level above the reference plane (13) which corresponds to the diameter (d0) of the said log (10) at its end opposite the said butt end. Thereafter, the logs (10) are flattened in this lowered position up to the reference plane (13) (FIG. 1).

Description

The invention relates to a method for flattening tree trunks with a curved longitudinal center line, in which the tree trunks are conveyed in the lying position with their convex side up and their concave side down in the longitudinal direction and flattened on the concave side in the region of an earth end from below and before the flattening in one position are measured, in which they lie only at end points of the concave side on a reference plane, the position of a first point of the tree trunk being determined after its elevation above the reference plane, and the tree trunks on the reference plane at the end of the earth when the end of the end facing away from the ground is continuously supported be lowered far so that the first point lies in a predetermined plane, and the tree trunks are flattened in this lowered position up to the reference plane.

A method and a device of the type mentioned above are known from DE-OS 37 30 865.

As is well known, tree trunks that are to be processed into finished products such as squared timber, boards and the like in sawmill systems have grown strictly straight only in exceptional cases due to natural conditions. In practice, it has been shown that the tree trunks delivered generally have a curved longitudinal center line, so that this odd growth form must be taken into account when processing the tree trunks in order to obtain an optimal wood yield. Another possible source of error in such tree trunks is the shape of the so-called earth end, ie the thickening of the trunk in the transition to the root area. Tree trunks are sawn off as close to the ground as possible for the sake of optimal yield, so that a considerable proportion of the tree trunk length, for example one meter, widens conically progressively and thus has a considerably larger cross-section than the otherwise more or less regularly tapered rest Tree trunk. If a tree trunk of this type with the end of the earth now lies on a flat contact surface of a conventional transport device for sawmill systems, it would it also lies very obliquely with the otherwise straight longitudinal center line, because the earth end with its much larger diameter allows the thicker end of the tree to stand up.

If a tree trunk has grown oddly at the same time and has a well-formed earth end, these errors may add up and it is difficult to feed the tree trunk into a position in which an optimal wood yield is guaranteed.

In this context, it is known from DE-PS 32 44 393 to at least partially flatten the tree trunk at its lateral surface section concavely curved in the longitudinal direction of the trunk at its earth end in a plane which is approximately parallel to one of the two trunk ends at the other in the longitudinal direction with a convex curved lateral surface section Tribal tangent plane.

In the known method and the known device, the end of the earth is flattened on one side on the concave curved side of the tree trunk, so that the tree trunk comes to a flatter support on a conveyor and therefore a better wood yield is achieved.

However, it has been shown in practice that the method mentioned above or the associated device, in particular in the case of very strongly curved tree trunks, does not result in optimum wood yield, so that there is still a need to further develop the positioning or preprocessing of the tree trunks in such a way that also optimal tree yield is guaranteed with very strongly curved tree trunks.

In the method known from the aforementioned DE-OS 37 30 865, the tree trunks are measured before flattening in such a way that the position of the first point on the concave side is determined as the point of greatest deflection after the distance from the earthed end point and after it has been raised above the reference plane becomes. The tree trunk is then lowered so far at the end of the earth that the first point lies in the reference plane.

Although the known method can be used with advantage in many cases, there are also cases in which even better results are desirable for certain types of tree or for certain typical types of tree growth.

The invention is therefore based on the object of developing a method and a device of the type mentioned at the outset in such a way that this wish is taken into account.

According to the method mentioned in the introduction, this object is achieved according to the invention in that the first point on the convex side marks the lowest point between the highest elevation and the end of the earth, and in that the predetermined plane lies at a height above the reference plane which corresponds to the diameter of the tree trunk at the end facing away from the earth.

The object on which the invention is based is completely achieved in this way because the abovementioned measures enable an even higher wood yield in a large number of tree species and also in certain types of tree growth than is the case according to the method mentioned at the beginning. In addition, the method according to the invention has the advantage that it is easier to carry out in practice because only two diameters must be determined.

Further advantages result from the description and the attached drawing.

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

Fig. 1

eine Seitenansicht eines ungerade gewachsenen Baumstammes mit ausgeprägtem Erdende sowie den im Rahmen der vorliegenden Erfindung interessierenden Meßpunkten mit ihren Koordinaten;

Fig. 2

den Baumstamm der Fig. 1, jedoch in einer zu einer Bezugsebene erfindungsgemäß einseitig abgesenkten Stellung;

Fig. 3

eine äußerst schematisierte Seitenansicht einer Vorrichtung zur Durchführung des erfindungsgemäßen Verfahrens;

Fig. 4 und 5

Ansichten in Richtung der Ebene IV-V-IV-V der Fig. 3 für zwei unterschiedliche Förderpositionen von Baumstämmen.

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

Fig. 1

a side view of an odd tree trunk with a pronounced end of the earth and the measuring points of interest in the context of the present invention with their coordinates;

Fig. 2

the tree trunk of Figure 1, but in a position lowered on one side according to the invention to a reference plane.

Fig. 3

an extremely schematic side view of an apparatus for performing the method according to the invention;

4 and 5

Views in the direction of the plane IV-V-IV-V of FIG. 3 for two different conveying positions of tree trunks.

In Fig. 1, 10 designates a tree trunk of natural growth, the longitudinal center line 10a of which is curved.

The tree trunk 10 is arranged horizontally, so that a convexly curved side 11 is at the top and a concavely curved side 12 is at the bottom. In this position, the tree trunk 10 lies on a reference plane denoted by 13, which can be, for example, an upper level of a conveying device of a sawmill system.

The left, thinner end of the tree trunk 10 in FIG. 1 has a first point 20 and a second point 21 as end points of the thinner end and the diameter of the tree trunk 10 at the thinner end is denoted by d₀. At the opposite, thicker trunk end, the tree trunk 10 lies with a third point 22 on the reference plane 13. A fourth point 23 marks the point of highest elevation on the convex side 11 of the tree trunk 10. A fifth point 26 marks on the convex side 11 the lowest point between the fourth point 23 of the highest elevation and the end of the earth 27. The height of the tree trunk 10 in the fifth Point 26 is denoted by h.

The measured values d₀ and h can be determined using measuring devices known per se, as will be explained further below with reference to FIGS. 3 to 5.

In order to pre-process the tree trunk 10 in a manner that enables subsequent processing with optimum wood yield, the tree trunk 10, as shown in FIG. 2 in detail, should now be lowered into a position in which the thinner end of the tree trunk 10 matches the first Point 20 on the reference plane 13 remains that the thicker end of the tree trunk 10 is lowered so far with the earth end 27 that the fifth point 26 on the convex side 11 comes to lie at the height of the second point 21 above the reference plane 13.

gehorcht. Um diesen Absenkwert A wird der Baumstamm 10 etwa in der Radialebene abgesenkt, die durch den fünften Punkt 26 definiert ist, d.h. etwa im Bereich des Überganges vom Erdende 27 zum übrigen Baumstamm 10.In order to achieve this, a lowering value A is determined from the previously determined measured variables d₀ and h, which corresponds to the relationship:

$\text{A = h - d₀}$

obey. By this reduction value A, the tree trunk 10 is lowered approximately in the radial plane which is defined by the fifth point 26, ie approximately in the region of the transition from the earth end 27 to the remaining tree trunk 10.

As FIG. 2 shows, the tree trunk 10 arrives from its starting position shown in dashed lines there, which corresponds to that of FIG. 1, into its end position drawn in solid lines. The seventh point 26 becomes 26 'and comes to lie at the height d 13 above the reference plane 13.

In this lowered position, the tree trunk 10 is now flattened from below to the reference plane 13, so that the area designated by 30 in FIG. 2 and hatched there is cut or sawn off.

The tree trunk flattened in this way now has an optimal contour in the horizontal direction for subsequent processing from the point of view of the best possible use of space. The subsequent processing can e.g. consist in a manner known per se that the flattened tree trunk 10 is now also flattened on the remaining 3 sides and then side boards or squared timbers are separated from the flattened sides.

In the exemplary embodiment of a known device shown in FIG. 3, which can also be used to carry out the method, as previously explained with reference to FIGS. 1 and 2, 40 designates a first conveyor device, for example a conveyor belt, on which the tree trunk 10 is promoted from left to right in Fig. 3. The earth end 27 is conveyed ahead in the conveying direction, but this does not have to be the case, because even with a corresponding adaptation of the elements still to be explained below, a conveyance of the tree trunk 10 with the thin end ahead would also be possible without further ado.

The tree trunk 10 passes through a light curtain 41 on its way in the first conveyor device 40, as will be explained further below with reference to FIGS. 4 and 5. The light curtain 41 is connected to a control unit 42, so that all the characteristic values d₀, d₁ and d _max already explained for FIG. 1 are supplied to the control unit 42. The control unit 42 determines the lowering value A from these input values and uses it to control a lifting device 43 which grasps the tree trunk 10 in the region of the end of the earth. As shown in Fig. 3, after leaving the first conveying device 40, the tree trunk 10 'projects freely with its earth end 27, so that the earth end 27' can be lowered by the lowering amount A when the thin end of the tree trunk 10 'is continuously supported. The area 30 thus passes below the reference plane 13 and can be removed by means of a milling cutter 44 or another suitable tool. It goes without saying that, instead of the lifting device 43 acting from above and drawn in in FIG. 3, a lifting device 43 'acting from below can also be used in order to lower the earth end 27' in the manner described.

The flattened tree trunk 10 '' then arrives at a second conveyor 45, from which it receives further processing stations, e.g. is further fed to flat milling cutters, corner milling cutters, cut-off and cross-cut saws and the like, as is known per se.

4 and 5 show the tree trunk 10 in two positions when passing through the light curtain 41. It can be seen that the light curtain 41 preferably consists of a rectangular frame which surrounds the first conveyor device 40 on all sides. In one vertical leg of the frame, light transmitters 50 are attached, which are opposed by light receivers 51, for example photodiodes or the like, on the other vertical leg. In this way, a curtain of light rays 52 is created, ie a plurality of horizontally aligned light barriers arranged one above the other, which are more or less interrupted by the contour of the tree trunk 10. 5 clearly shows that in this way the contour of the tree trunk 10 can also be detected without contact in the region of the convex side 12.

In the explanation of the device according to FIGS. 3 to 5, it should also be added that the lifting device 43 or 43 'in the lowering plane marked A in FIGS. 1 and 2 can act with the fifth point 26, but does not have to act, because, of course, lowering is also possible in the radial plane defined by the third point 22 or in another radial plane, in which case the specified relationship for the lowering value A would have to be adapted accordingly.

Claims (1)

Method for flattening building trunks (10) with a curved longitudinal center line (10a), in which the tree trunks (10) in the lying position are conveyed with their convex side (11) upwards and their concave side (12) downwards in the longitudinal direction and on the concave Side (11) in the area of an earth end (27) is flattened from below and measured before flattening in a position in which they rest only on end points (20, 22) of the concave side (12) on a reference plane (13), whereby the position of a first point (26) of the tree trunk (10) is determined after it has been raised above the reference plane (13), and the tree trunks (10) with continuous support of the end point (20) facing away from the earth end on the reference plane (13) at the end of the earth (27 ) are lowered so far that the first point (26 ') lies in a predetermined plane, and the tree trunks (10) are flattened in this lowered position up to the reference plane (13), characterized in that the first point (26) on the convex side e (11) marks the lowest point between the highest elevation (23) and the end of the earth (27), and that the predetermined plane lies at a height above the reference plane (13) which corresponds to the diameter (d₀) of the tree trunk (10) corresponds to the end facing away from the earth.

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