EP0652088A1 - Method and device for processing tree trunks - Google Patents

Abstract

A method and device are used for processing treetrunks (50) into wood products. The device comprises a circular saw (40) which has a spatially fixed deflecting element (44) parallel to a circular saw blade (41). The deflecting element (44) extends into the engagement region of teeth (42) of the circular saw blade (41). As side boards (side cuts) (51) are cut off, the deflecting element diverts these out of the plane of the teeth (42) from a main stock (52) of the treetrunk (50) directly after the passing of the teeth (42). The device further comprises first means for removing a wane (53) of the treetrunk (50), as well as second means for trimming the side boards (51) to predetermined lengths. The first means are constructed as edging-chipper assembly (60 to 63) and are arranged, in the conveying direction (54) of the treetrunk (50), directly downstream of the circular sawblade (40) but upstream of the second means. <IMAGE>

Description

The invention relates to a method for dismantling a tree trunk into wood products, in which side boards are separated from a main article of the tree trunk by means of a circular saw, the side boards being bent out of the plane of the teeth immediately after passing the teeth of the circular saw by means of a fixed deflecting element and subsequently in be cut to a predetermined length, and measures are also taken to remove a wall edge of the tree trunk in such a way that side boards are trimmed on both sides.

The invention further relates to a device for disassembling a tree trunk into wood products, with a circular saw that has a spatially fixed deflecting element parallel to a circular saw blade that extends into the engagement area of teeth of the circular saw blade and when the side boards are detached from a main item of the tree trunk, the side boards immediately after passing the teeth bends out of the plane of the teeth, the device further comprising first means for removing a forest edge of the tree trunk and second means for cutting off the side boards to a predetermined length.

A method and a device of the type mentioned above are known from WO 88/02683.

In the known method and the known device, an otherwise conventional circular saw is provided with a spatially fixed, disc-shaped deflecting element which is arranged parallel to the circular saw blade and extends in the edge region up to the engagement region of the teeth. The deflector is slightly conical. If the circular saw z. B. separates a side board from a main item of a tree trunk, the separated side board runs on the conical, fixed deflector and is thus bent from the parting plane. This has the advantage that the separated side board comes out of engagement with the rotating circular saw blade immediately after passing the teeth of the circular saw blade, so that the generation of frictional heat is avoided.

In the known method and the known device, no special measures are concerned to remove the tree trunk or the side board from a forest edge, ie bark remains on the edge free the side board. The known method and the known device are based on an already pretreated, namely a profiled tree trunk.

A profiled tree trunk is understood to mean one that has already been pretreated in previous processing steps in such a way that the entire bark has already been removed from the originally raw tree trunk and a profile has already been produced in cross-section in which only side boards have to be cut off or one The log has to be broken down into other wood products (boards, planks, squared timber and the like).

Methods and devices for profiling tree trunks are known, for example from DE-PS 32 44 393, DE-PS 29 28 949 and DE-PS 29 18 622.

In these known methods and devices, the initially raw tree trunk is flattened on all sides, so that a cross-sectional shape of almost square shape is created, but in the area of the corners of the square there are still bark remains, the so-called forest edges. In subsequent corner milling stations, these corners with forest edges are now milled out, so that a cross-sectional shape is created which has the shape of a square with milled square corners. The corners can also be milled in several stages. Subsequent separating cuts can now be used to separate the laterally protruding rectangular profiles as side boards. These side boards are then cut to length using standard cross-cut saws. This can either happen while the side boards have not yet been completely separated from the main goods, i.e. are still materially connected to them, but it is also possible for the side boards First cut off the main goods over the entire length of the tree trunk and then cut to length in separate work steps.

In addition, it is generally known to only flatten a raw log at the side and then, without any profiling, to cut off side boards, which are then still provided with the forest edges on their sides. These separately handled side boards can then be guided over so-called trimming units in order to separate the forest edges on both sides. The trimming machiners can be designed as circular saws with which the forest edge is sawn and then cut, but tools are also known with which the forest edges are cut when they are cut off.

In a method and a device of the type mentioned at the outset which already have a profiled, i.e. Milling a tree trunk at the corners can, however, cause problems in practice if the corner milling cutters are not properly positioned in relation to the circular saws, which cause the side boards to be cut off after the corners have been milled out. This applies in particular if the tree trunk is handled again during the machining process between the corner milling station and the circular saw, for example it is conveyed over long distances or even rotated. Then it can happen that the kerf of the circular saw loses its reference position to the two surfaces of the milled corner and either side boards with incorrect dimensions or with collar-like projections are produced.

Another disadvantage of profiling tree trunks using corner milling cutters is that the corner milling cutters, with their rotating circumferential surface, plunge tangentially into the wood of the tree trunk and just support yourself on the tree trunk. This leads to the formation of chips which are thickened at one end and tapered at the other end and which are therefore referred to in technical terms as "comma chips". However, such shavings are undesirable for customers of such shavings, namely the cellulose industry, because fractions with a constant length and thickness are desired for the further processing of the shavings in cellulose production.

From GB-PS 1 086 450 a method and an apparatus for processing tree trunks are known. Then the tree trunks are first flattened on both sides by means of the first band saws, by cutting off a part with a circular cross-section on both sides and a forest edge on the circular-arc-shaped surface. The tree trunk flattened in this way is then rotated by 90 ° and flattened again on both sides by means of a second band saw unit. The parts separated in this way are fed to further band saws and circular saws in order to produce boards free of forest edges. These boards without forest edges are then cut to a predetermined length in a sorting device by means of circular saws.

The invention is therefore based on the object of developing a method and a device of the type mentioned at the outset such that the disadvantages mentioned above are avoided. In particular, dimensionally accurate and form-accurate side boards are to be produced, the chips being produced being suitable for subsequent cellulose production.

According to the method of the type mentioned, this object is achieved according to the invention in that the side boards in the untrimmed state are fed to a trimming machine unit immediately after turning and only then are they physically separated from the main goods.

According to the device mentioned in the introduction, the object is achieved according to the invention in that the first means are designed as a trimming unit and are arranged in the conveying direction of the tree trunk directly downstream of the circular saw blade, but upstream of means for materially separating the side boards from the main goods.

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

According to the invention, in contrast to conventional profiling methods, the step of trimming the side boards is again postponed after the step of separating the side boards. However, in order to ensure an association between the circular saw and the trimming tool, in other words, a high degree of dimensional and shape accuracy, the side boards are trimmed in a state in which they are still materially connected to the tree trunk. This is the case immediately after passing the circular saw. One takes advantage of the fact that a certain circular saw is used which not only separates the side boards from the main goods, but also bends them out of the parting plane. Then you have the side boards immediately behind the circular saw at a distance from the main goods and you can trim the untrimmed side board there with the space you need for trimming tools. As a result of the material unity between the side board and main goods, extreme dimensional and shape retention is possible in this way because there is a rigid mechanical connection between the side board in the area of the circular saw and the leading section of the side board in the area of the trimming tool.

In a preferred development of the invention, a rotating trimming chipper is used as the trimming machinist, the diameter of which is dimensioned such that the side boards be moved approximately diametrically past the trimmer.

This measure has the advantage that the plane of engagement of the chipper on the wood is almost below 90 ° to the direction of movement of the side boards. The wood of the side board thus acted upon in the radial direction is broken down into chips in this way, the thickness of which is constant. These chips are referred to in technical jargon as "constant thickness chips" and are gladly accepted by the cellulose industry because they are suitable for the production of cellulose. The procedure according to the invention, namely trimming the side board at a distance from the main goods, thus has the systematic advantage over the known profiling methods that the chips can be produced in a more favorable form.

This applies in particular if, according to a development of the invention, the side boards are supported in the area of engagement of the trimmer by means of an abutment.

This measure has the advantage that chip production with chips of equal thickness is particularly successful.

Further advantages result from the description of the attached drawing.

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

Fig. 1

einen unbearbeitetenden Baumstamm im Radialschnitt;

Fig. 2

den Baumstamm gemäß Fig. 1 gemäß einem ersten Bearbeitungsschritt bei einem herkömmlichen Profilierverfahren;

Fig. 3

den Baumstamm gemäß Fig. 2 gemäß einem weiter nachfolgenden Bearbeitungsschritt;

Fig. 4

den Baumstamm gemäß Fig. 3 gemäß einem noch weiter nachfolgenden Bearbeitungsschritt, nämlich dem Abtrennen eines Seitenbrettes;

Fig. 5

eine Darstellung, ähnlich Fig. 3, jedoch zur Veranschaulichung eines möglichen Verfahrensfehlers;

Fig. 6

eine Darstellung ähnlich Fig. 4, zur Veranschaulichung der sich aufgrund des Verfahrensfehlers ergebenden fehlerhaften Holzerzeugnisse;

Fig. 7

eine Darstellung ähnlich Fig. 3 zur Erläuterung der Spanherstellung bei einem herkömmlichen Profilierverfahren;

Fig. 8

eine Draufsicht auf die Anordnung gemäß Fig. 7;

Fig. 9

eine Seitenansicht einer herkömmlichen Kreissägeanordnung zur Veranschaulichung der dort obwaltenden Umstände bei der Spanherstellung;

Fig. 10

eine Draufsicht auf ein Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung;

Fig. 11

eine Schnittdarstellung entlang der Linie XI-XI von Fig. 10.

An embodiment of the invention is shown in the drawing and is explained in more detail in the following description. Show it:

Fig. 1

a raw log in radial section;

Fig. 2

1 according to a first processing step in a conventional profiling method;

Fig. 3

2 according to a further subsequent processing step;

Fig. 4

3 according to a still further processing step, namely the detachment of a side board;

Fig. 5

a representation, similar to Figure 3, but to illustrate a possible procedural error;

Fig. 6

a representation similar to Figure 4, to illustrate the faulty wood products resulting from the process error.

Fig. 7

a representation similar to Figure 3 to explain the chip production in a conventional profiling process.

Fig. 8

a plan view of the arrangement of FIG. 7;

Fig. 9

a side view of a conventional circular saw arrangement to illustrate the circumstances prevailing there during chip production;

Fig. 10

a plan view of an embodiment of a device according to the invention;

Fig. 11

a sectional view taken along the line XI-XI of Fig. 10th

Fig. 1 shows a radial section of a tree trunk 10, which in the simplified representation consists of log 11 and an outer surrounding bark 12. Longitudinal planes on the tree trunk 10 are indicated by 13, along which chipper tools can be guided in order to flatten the tree trunk 10 on all sides.

The result of the flattening is shown in Fig. 2. It can be seen that the tree trunk 10 now has an approximately square cross-sectional shape, which is determined on the sides by the planes 13. Only in the area of the corners are so-called forest edges 14 remaining as remains of the bark 12. Axially extending corners are indicated by 15 in FIG. 2, which can subsequently be attached by means of so-called corner cutters in order to remove the forest edges 14.

The result of this corner milling is shown in FIG. 3, where the corners 15 with their boundary surfaces can be clearly seen in the left half. 3 in FIG. 3 indicates that a subsequent saw cut can be made, the thickness of the kerf being designated by d.

4 shows the result of the saw cut 16. The originally still one-piece, profiled tree trunk has now been divided into a so-called main article 18 and a side board 17. A side board can also be separated there by corresponding steps on the right side of the tree trunk in FIG. 4, and the same applies to the top and bottom of the tree trunk, for which purpose the tree trunk is expediently rotated by 90 °, so that the same units can be used which previously carried out the processing steps illustrated in FIGS. 2 to 4.

In Fig. 5 it is now illustrated that the profiling and cutting of tree trunks explained above can lead to certain errors. If, instead of being adjusted in their desired position, the corner milling cutters are adjusted with a certain offset, which is denoted by x in FIG. 5, then not a corner 15 according to FIG. 3 but rather a corner 15 ′ according to FIG. 5, the vertical surface of which is generated 5 is offset to the left by the amount x.

FIG. 6 shows the sequence when the saw cut 16 is subsequently made in the desired position of the saw blade. Because of the offset x of the corner 15 ', a side board 17' is now created, on the right side of which projections 19 remain. It is obvious that a side board 17 'produced in this way cannot be sold, but rather must be subjected to further post-processing, which leads to corresponding costs.

It follows from the foregoing that when profiling and subsequently dismantling tree trunks, an exact assignment of the tool positions in successive processing steps must be guaranteed, in connection with the conveyance of the tree trunks between the different processing positions. The problems shown with reference to FIGS. 5 and 6 arise to a greater extent, the less precise the positioning of the tools and the greater the distances between the processing positions and thus the travel distances of the tree trunk. When moving the tree trunks In fact, changes in the position of the tree trunk can also result in assignment errors which lead to the consequences illustrated in FIGS. 5 and 6.

Another aspect of conventional profiling methods is shown in FIGS. 7 and 8.

FIG. 7 shows, in a representation that corresponds to the machining step according to FIGS. 2 and 3, a corner milling cutter 25 that can be rotated about an axis 24. The axis 24 is perpendicular to the conveying direction of the tree trunk 10, which is indicated in FIG. 8 by an arrow 26 . The corner milling cutter 24 rotates in a direction which is indicated by an arrow 27 in FIGS. 7 and 8.

The corner milling cutter 25 essentially produces the corner 15 with its end face, as can be clearly seen from the illustration in FIG. 8. The corner milling cutter 25 plunges essentially tangentially into the wood of the tree trunk 10. It supports itself against the tree trunk 10 itself. Because of these engagement conditions of the corner milling cutter 25 on the tree trunk 10, chips 28 arise in the engagement area, which are thickened at the left end in FIG. 8 and tapered at the right end in FIG. 8. This is because the corner milling cutter 25 engages exactly tangentially in the wood of the tree trunk 10 at the right end of the chip 28 in FIG. 8 and at a finite but small angle at the left end in FIG. 8. The mean pressure angle is designated by α in FIG. 8. It is exaggeratedly large there and in practice is in the range of a few degrees.

In this way, chips 28 are formed in the form of so-called "comma chips" which are thick at one end and thin at the other end.

The chips generated when cutting wood are used as raw material for the cellulose industry and are largely removed from it. For the production of cellulose, however, it is important to have the wood chips available in a uniform structure, because the wood chips are broken down chemically in the production of cellulose and therefore one wants to have chips that have a constant thickness so that the chips in the further one Processing can be disassembled evenly. This is not the case for chips of irregular shape with different thicknesses because the thinner areas are more likely to decompose than the thicker areas. The so-called "comma chips" are therefore more problematic in further processing and are less accepted by the cellulose industry, in any case at lower purchase prices.

In comparison to this, FIG. 9 shows a situation such as that which arises, for example, in a conventional circular saw, with which a board is sawn or slotted, for example.

In this situation, a board 30 is sawn or slit by means of a circular saw 31, the circular saw 31 rotating about an axis 32, as indicated by an arrow 33. Another arrow 34 shows the advance of the board 30 relative to the circular saw 31. 35 denotes an abutment on which the board 30 rests in the vicinity of the engagement area of the circular saw 31.

Since the circular saw 31 has a very large diameter, the arrangement can be made such that the board 30 runs approximately diametrically past the circular saw blade, i.e. practically along a diameter, this measure being limited only in that a finite dimension for a drive shaft of the circular saw blade must be provided in the area of the axis 32.

With large diameters of the circular saw blade, however, this plays a negligible role, so that the angle between the direction of engagement of the circular saw 31 (arrow 33) and the advancing direction of the board 30 (arrow 34) is practically 90 °, as with an angle β in FIG. 9 indicated.

The chips 36 formed in this way have a constant thickness over their entire length and are therefore referred to in technical terms as "uniform thickness chips". These chips are economically more valuable than "comma chips" as explained above.

In the exemplary embodiment of the invention shown in FIGS. 10 and 11, this knowledge is now used.

In the device according to the invention, a circular saw 40 is provided with a circular saw blade 41 which is provided with teeth 42 on its circumference. A drive shaft 43 ensures a rotation of the circular saw blade 41. Parallel to the circular saw blade 41, a spatially fixed, disc-shaped deflecting element 44 is provided, which is slightly conical, as can be seen particularly clearly in FIG. 11. The spatially fixed deflecting element 44 is held by a holder 45, which is arranged, for example, concentrically with the drive shaft 43. The axis of the circular saw 40 is designated 46. An arrow 47 defines the direction of rotation of the circular saw blade 41.

Further details on the structure and function of the circular saw 40 can be found in WO 88/02683, to which reference is made to avoid repetition.

A tree trunk 50 is guided past the circular saw 40 in order to separate side boards 51 from a main item 52. The log 50 is only flattened when it reaches the circular saw 40, but is not profiled in the conventional sense, i.e. not provided with axial corners. The tree trunk 50 is therefore still affected by forest edges 53.

The side board 51 is now separated from the main item 52 by means of the circular saw 40. The side board 51 is bent out of the plane of the circular saw blade 41 due to the conicity of the fixed deflecting element 44, as can be seen particularly clearly in FIG. 11. Due to the taper of the deflecting element 44, the side board 51 is also displaced laterally slightly from the axis of the tree trunk 50, as can be seen in FIG. 10.

Downstream of the direction of conveyance of the tree trunk 50 indicated by an arrow 54, a trimming unit is arranged directly behind the circular saw 40. The trimming unit consists of a first pair of rollers 60, a second pair of rollers 61 arranged at a distance downstream therefrom and a trimmer cutter 62 positioned between the roller pairs 60, 61. Immediately upstream of the trimmer cutter 62, the side board 51 is supported from below by an abutment 63, a so-called counter knife . With 56, 66, 67 the axes of rotation of the pairs of rollers 60, 61 and the trimmer 62 are designated, while arrows 68, 69 and 70 define their direction of rotation.

The trimming machiner unit 60 to 63 is arranged somewhat above the main goods 52 which continue to pass, as shown in FIG. 11. This is possible because, as mentioned, the side board 51 has been bent out of the parting plane. The roller pairs 60, 61 now cause the side board 51 to bend back in a direction parallel to the conveying direction of the main item 52.

The side board 51 is trimmed in the trimming unit 60 to 63 and leaves it as a trimmed side board 51a, as can be seen from FIG. 10.

Since the trimmer hogger unit 60 to 63 is arranged at a distance above or next to the main goods 52 which continue to run, a trimmer hogger 62 with a relatively large diameter D can be used, which is indicated schematically in FIG. 11. The edges of the trimming cutter 62 then run practically at a pressure angle of approximately 45 ° in the radial direction through the wood in the region of the forest edges 53, the abutment 63 also contributing to the fact that chips of uniform thickness are formed, as already explained further above in FIG. 9 has been.

As a result of the close spatial association of the circular saw 40 and the trimming cutter assembly 60 to 63, a high degree of dimensional accuracy is also ensured because the side board 51 is still materially connected to the main product 52 when it passes through the trimming cutter assembly 60 to 63.

The trimmed side board 51a is trimmed downstream of the trimmer unit 60 to 63 to commercially available lengths.

This can either be done by arranging a cross-cut saw (not shown) downstream of the trimming unit 60 to 63 in order to separate the side board 51a, which is still materially connected to the main product 52, from the main product 52 and to cut it to length.

On the other hand, one can also first trim the side board 51, completely separate it from the main goods 52, as shown in FIGS. 10 and 11, and then cut it to another location after separate handling and transport to a cross-cut saw (likewise not shown).

Claims (6)

Method for cutting a tree trunk (50) into wood products, in which side boards (51) are separated from a main item (52) of the tree trunk (50) by means of a circular saw (40), the side boards (51) immediately after passing the teeth ( 42) the circular saw (40) is bent out of the plane of the teeth (42) by means of a fixed deflecting element (44) and subsequently cut to a predetermined length, measures being also taken to remove a forest edge (53) from the tree trunk (50), such that side boards (51) with trimmed edges are produced, characterized in that the side boards (51) in the untrimmed state are fed to a trimming machinist unit (60 to 63) immediately after the bending and only then are they materially separated from the main goods (52). A method according to claim 1, characterized in that a rotary trimming chipper (62) is used as the trimming cutter unit (60 to 63), the diameter (D) of which is dimensioned such that the side boards (51) approach approximately at about 45 ° pressure angle the trimmer (62) are moved past. Method according to claim 2, characterized in that the side boards (51) are supported in the area of engagement of the edger cutter (62) by means of an abutment (63). Device for cutting a tree trunk (50) into wood products, with a circular saw (40) which, parallel to a circular saw blade (41), has a spatially fixed deflecting element (44) which extends into the engagement area of teeth (42) of the circular saw blade (41) extends and when separating side boards (51) from a main item (52) of the tree trunk (50) the side boards (51) immediately after passing the teeth (42) from the plane of the teeth (42), the device further comprising first means for removing a forest edge (53) from the tree trunk (50) and second means for cutting off the side boards (51) to predetermined lengths, characterized in that the first means are designed as trimming machiners (60 to 63) and in the conveying direction (54 ) of the tree trunk (50) immediately downstream of the circular saw blade (40), but upstream of means for materially separating the side boards (51) from the main goods (52). Apparatus according to claim 4, characterized in that the trimmer hogger unit (60 to 63) comprises a rotating trimmer hogger (62), the diameter (D) of which is dimensioned such that the side boards (51) approximately at about 45 ° pressure angle on the Trimming machiners (62) can be moved past. Apparatus according to claim 5, characterized in that an abutment (63) for the side boards (51) is provided in the area of engagement of the edging cutter (62).

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