EP0604891B1 - Method and device for slicing planks of predetermined thickness from squared timber - Google Patents

Abstract

The present invention concerns a method for cutting squared timber into a number of thin boards. Individual boards 32 are cut off by a blade 30 from the squared timber in each of the successive cutting machines 14a-g, essentially in longitudinal direction of the squared timber. The thickness of the squared timber 26 is selected in such a way that, once an integral number of boards having a predetermined thickness are cut off, a residual board remains which is reduced to the same thickness d as the boards 32 by shaving. The shaving preferably takes place by placing a planer 18 after the last cutting machine 14g. The installation 10 is equipped with a material feed 12 and a conveying system 20 for removing the cut boards, the cutting machines and the planer are also connected to one another by conveying devices 16, 24.

Description

The invention relates to a method for cutting a squared timber into a number of thin boards of predetermined thickness according to the preamble of claim 1. The invention further relates to a system for performing such a method.

The cutting generation of relatively thin boards from a squared timber or a device therefor are known, for example, from DE-A 37 02 909.

If thin boards are processed into laminate products such as composite panels, wall and floor panels or glue binders, for the manufacture of which they are generally combined into layers with a larger surface area, it is necessary that the thin boards to be processed have the same thickness as possible, so that they are assembled There were no surface gradations. In contrast, different layers can have different thicknesses. If thin boards are produced by sawing from a square timber, the thicknesses of the boards can generally be determined or adjusted relatively precisely by appropriate adjustment of the saw blades. The required initial thickness of a squared timber for producing a certain number of boards of the same thickness can also be determined relatively accurately with additional consideration of the thickness of the saw cut joints.

When cutting boards, the actual thickness of a board depends on various process parameters, including the particular state of the wood, so that it is often only possible to react to the knife setting after measuring a cut board in order to correct the thickness of the boards subsequently separated from a squared timber.

Such a method for thickness correction is described in DE-A 40 26 346, for example. Board cutting systems with lower output often only use one or two cutting machines. After one or two boards have been cut off in two cutting machines arranged immediately one behind the other, the squared timber is generally sent back in front of the machines for a further passage through the machines until it is completely divided into the thin boards to be produced. With this procedure, there is enough time to correct the knife setting after the thickness of a cut board before the next pass of the timber through the machines.

In systems with high output, it is preferable to arrange as many cutting devices or cutting machines directly in series in succession that a square timber of a certain thickness can be processed completely into thin boards of desired, predetermined thickness in one, usually straight-line passage through the system. If one furthermore takes into account that today when cutting thin boards, cutting speeds of 90-140 m / min and above are used, the throughput of a squared timber for its complete division by a sequence of cutting devices arranged one behind the other becomes so short that it is acceptable Effort measuring a produced board from a cutting device and a resulting correction of the knife position of the next cutting device can no longer be carried out. This possibility is practically completely ruled out if several squared timbers are led through the sequence of cutting devices in direct succession. The knife correction could then only take place while a board is in separation, which would give it an uneven thickness over its length.

The invention is therefore based on the object of proposing a method and a system with which it is possible to produce boards of a predetermined thickness even in the case of a succession of cutting devices which divide a squared timber into thin boards in one pass.

According to the invention, this object is achieved in terms of the method by the characterizing features of patent claim 1 and in terms of the device by the characterizing features of patent claim 3.

The great advantage of cutting thin boards is that compared to manufacturing by sawing dividing a square timber, up to 40% of the raw material wood can be saved, since no cutting dust is produced during cutting. However, this advantage could not be exploited if cut boards produced for the production of high-output laminate products cannot be used because the thickness constancy of the boards cannot be fully controlled.

Therefore, according to the invention, a certain machining of the rest of the board is accepted. Theoretically, there would also be the possibility of dimensioning the squared timber somewhat thicker than necessary in order to obtain a thin waste board in the last cutting device, which is discarded. There are limits to this method, however, because a very thin last section, ie a section that is thinner than the minimum lamella thickness that can be produced by the cutting machine, can no longer be handled in the cutting machines as a so-called residual board. Even a procedure such that a thin oversize layer is cut off from the remaining squared timber in the last cutting device and the squared residual wood leaving the last cutting device is used as the last board, since in the cutting devices only the thickness of the separated layer due to the distance can be determined between the contact surface for the squared timber and the knife. So if you only wanted to cut a thin layer of the residual square timber fed to the last cutting device, this residual square timber would first have to be measured in order to determine the thickness of the layer to be cut off and adjust the knife accordingly. However, this is exactly the process that cannot be managed with reasonable effort at high speeds and immediately following squared timbers. It could also be the case that the residual square timber fed to the last cutting device is no longer completely parallel in its main surfaces after several boards have been cut off. When cutting a thin oversize layer, it would then be cut off with the same thickness and the skewness would remain in the last board.

The object of the invention is therefore achieved in an optimal manner against the rules of avoiding waste chips in that the advantage of cutting boards is neglected to a small extent. By machining the remaining board in a way that does not cut off a coherent layer of wood - and in this way the term "machining" is to be understood here - less waste is ultimately accepted than if one were to do it consistently Carrying out the cutting technique would have to discard a remaining board, which in any case would have to be thicker than the maximum excess required by the machining aftertreatment.

The machining post-processing is preferably carried out by planing, in such a way that the rest of the board is guided with one of its main surfaces on a support surface and the machining is carried out from the other side. In this way, a lack of parallelism of the rest of the board can also be restored.

Cutting machines, which have proven themselves in practice, are constructed in such a way that the squared timber is guided on a support table and pressed against a knife edge which is approximately at a distance from the board thickness to be produced above the support table. The back of the knife serves as a support surface for the remaining square timber reduced by a board thickness and the board produced is led off obliquely downwards from the gap between the first support surface and knife edge and finally removed from the side of the machine.

It is also conceivable that a cutting machine contains several cutting devices one after the other, or that boards are cut from two sides of a square timber at the same time, but the previous practice is such that each cutting device is part of a separate cutting machine.

Since the squared timbers are practically guided on a horizontal table as they pass through the cutting machines, an arrangement lends itself in which a sequence of cutting machines is set up essentially immediately one behind the other, the cutting machines being connected to one another only by conveying or feeding devices for the squared timber and the squared timber can be guided in a straight line through the sequence of machines. Since the rest of the board to be reworked is basically the rest of the square timber leaving the last cutting device, which consequently does not have to be removed laterally from the cutting machines like the previously cut boards, the device for post-processing can also be used directly in continuation of the straight conveying direction of the squared timber Connect sequence of cutting machines.

A system with a sequence of cutting machines is expediently designed in such a way that squared timbers of a certain maximum thickness can be broken down into a certain number of thin boards in one pass. If, contrary to this design, fewer boards are to be produced in one pass, the system is advantageously to be equipped in such a way that the remaining board passes through the last, unnecessary cutting machines without a layer of wood is separated from it. For this purpose, the last cutting machines in a sequence of machines which are suitable for an idle run are to be equipped in such a way that their knives can be set to a board thickness of 0 mm, ie that the knife edge can be brought into the plane of the support table or below. The smooth passage of a residual board through a cutting machine can also be made more difficult by the counterpressure bar in front of each knife and rising from the support table. In an expedient embodiment of the invention, the machines provided for empty passage are therefore also additionally equipped so that the counter pressure bars can be moved back into the level of the support table or below.

The unimpeded passage of the rest of the board by a cutting machine can also be ensured in such a way that the cutting knife is replaced by a blind plate which has no cutting edge. The blind plate has the same dimensions as a cutting knife, so that a completely flat support and guide surface for the rest of the board is formed after inserting the blind plate.

An exemplary embodiment of a system is described below with which squared timbers can be divided into a number of thin boards of the same thickness.

Fig. 1

eine schematisch dargestellte Anlage zum Aufteilen eines Kantholzes in eine Anzahl dünner Bretter vorbestimmter Dicke,

Fig. 2

einen Schnitt durch den Messerbereich einer Schneidmaschine.

Show it:

Fig. 1

a schematically illustrated system for dividing a squared timber into a number of thin boards of predetermined thickness,

Fig. 2

a section through the knife area of a cutting machine.

The system 10 for dividing squared timbers 26 is composed of a material feed 12, a number of cutting machines 14a-g arranged one behind the other, which are connected to one another by transport devices 16a-f, a planing machine 18 arranged behind the last cutting machine 14g and a transport system 20 for transporting of the cut boards 32 together.

The material feed 12 can be designed as a roller conveyor in which at least some of the rollers are driven, but it can also, as shown here, be designed as a conveyor belt, on which squares 26 are fed to the cutting machine 14a-g. The squared timbers 26 are then guided at high speed, at least 90 m / min, preferably approximately 140 m / min, up to a maximum of 220 m / min, in the longitudinal direction through the cutting machines 14a-g arranged one behind the other. The cutting machines 14a-g have their own feed or transport devices. Conveyor belts 16a-f or roller conveyors are arranged between the cutting machines 14a-g for conveying the squared timber 26, as shown here. A discharge 22a-g for the cut boards 32 branches off from each cutting machine 14a-g. These discharges are part of the transport system 20, by means of which the cut boards 32 are fed for further processing. Roller conveyors or, as shown, conveyor belts can also be used here.

The last cutting machine 14g is connected to the planing machine 18 via a further conveyor device 24. That in the planer 18 Calibrated rest board is also fed to the transport system 20 and thus to the same further processing as the other boards 32.

The system 10 is operated in such a way that a squared timber 26 is fed to the first cutting machine 14a via the material feed 12. As can be seen from FIG. 2, the squared timber 26 is brought in the cutting machine 14a on a horizontal contact surface 28 to the knife 30 arranged above the plane of the contact surface. The knife 30 cuts a board 32 of predetermined thickness d, which is transported downwards. In order to achieve an optimal cutting profile, a counter-pressure bar 34 is arranged in the contact surface 28 in the cutting direction directly in front of the knife edge, which protrudes somewhat from the contact surface 28. The counter pressure bar 34 thereby exerts selective pressure on the squared timber 26, so that the gap caused by the knife edge in the squared timber 26 cannot spread out in an uncontrolled manner.

In this way, a board 32 of predetermined thickness d is cut off in each of the arranged cutting machines 14a-g on the underside of the square timber 26. With each pass through a cutting machine 14a-g, the thickness of the squared timber 26 is reduced by the amount of the board thickness d.

The number of cutting machines 14a-g arranged one behind the other depends on the maximum number of boards 32 which are to be cut from a square timber 26. Are squared timbers 26 of lower thickness cut so that fewer boards 32 are obtained or squares 26 of the same thickness become thicker boards 32 cut so that again fewer boards 32 are obtained, it may be that the remaining board to be planed has to pass through one or more cutting machines 14a-g without a board 32 being cut off there. As usual, the rest of the board is guided over the contact surface 28 of the cutting machines 14a-g. However, this flat transport surface would be interrupted by the protruding counter pressure bar 34, which becomes inoperative as soon as no board 32 is cut off in the cutting machine 14a-g. The counter pressure bar 34 is therefore displaceably arranged so that it can be lowered at least into the plane of the contact surface 28 if the cutting machine 14a-g is only passed by a remaining board without a board 32 being separated. The displaceable bearing 36 can be designed, for example, as a hydraulic bearing or as a mechanical bearing.

The same knife position and lowering of the counter pressure side can be selected if e.g. for maintenance work, any of the machines connected in series is run through without cutting.

According to the method, a square timber 26 is broken down into a number n of boards 32 in the system 10. After passing through several cutting machines 14a-g, in which n-1 boards 32 are cut off, a so-called residual board remains, which according to the method has a thickness which is slightly greater than the thickness d of the boards 32. After cutting off n-1 boards 32 the rest of the board is either fed directly to the planing machine 18 or any cutting machines 14a-g that are still present are passed without boards 32 being separated, in order to then be fed to the planing machine 18 via the conveyor device 24.

Despite precisely set cutting machines 14a-g, it can happen that this remaining board no longer has a uniform thickness. Since the surface of the squared timber 26 lying on the contact surface 28 has always been machined, this lower surface lying on the contact surface 28 is to be regarded as flat. Any irregularities in the thickness of the rest of the board are therefore advantageously removed from the top of the rest of the board.

The planing machine 18 is preferably equipped with planer shafts located at the top of the rest of the board. The planer shafts are designed so that they reduce the rest of the board to the predetermined thickness d by removing individual shavings.

The material loss caused by the removal of shavings is less than if a residual board whose thickness d1 was less than the predetermined thickness d were cut off in a last cutting machine 14a-g.

Claims (8)

1. A process to partition a squared timber (26) into a number of thin blanks (32), wherein single blanks (32) are separated one after another from the squared timber (26) essentially lengthwise thereof through slicing by means of a knife (30),
   characterized in that a squared timber is used, the thickness thereof in vertical direction with respect to the slicing plane of the knife (30) being slightly larger than the sum of the thicknesses of an integer number of blanks (32) having a predetermined thickness, and in that the residual blank ensuring from the partition is reduced to a predetermined thickness through machining.
2. A process according to claim 1, characterized in that the residual blank is reduced to said predetermined thickness through planing.
3. A plant for the partition of squared timbers (26) into a number of thin blanks (32) of a predetermined thickness, said plant having series of slicing appliances (14 a-g) disposed one after another to separate each blank purely by slicing from one side of a squared timber (26),
   characterized in that a machining device (18) is provided behind the series of slicing appliances (14 a-g) in order to reduce the thickness of the final or residual blank ensuring from the series of slicing appliances (14 a-g).
4. A plant according to claim 3, characterized in that the machining device is a planer (18).
5. A plant according to claims 3 or 4, characterized in that each slicing appliance out of the series of slicing appliances (14 a-g) is part of a separate slicing machine and in that the slicing machines are disposed one after another in a series.
6. A plant according to claim 5, characterized in that conveying devices (16 a-f) are provided between the slicing machines (14 a-g) for an essentially rectilinear further conveyance of the squared timber (26) or, respectively of each residual squared timber in lengthwise direction thereof across the series of slicing machines (14 a-g), and in that a conveying device (24) is provided behind the last slicing machine for an immediate further conveyance of the last residual squared timber constituting the last residual blank immediately into the machining equipment of the planer (18).
7. A plant according to at least one of the claims 3 to 6, wherein the slicing devices (14 a-g) have an abutment face (28) for a guidance of the squared timber (26), a knife (30) being disposed behind said abutment face (28) with respect to the direction of transport of that squared timber and being adjustable to a distance "d" from said abutment face (28) in the direction of said squared timber (26) and a backpressing shoulder (34) placed in front of said knife (30) and slightly projecting over said abutment face (28),
   characterized in that, for a run of the squared timber (26) without separation of a blank (32), said knife (30) and said backpressing shoulder (34) of at least on slicing device (14 a-g) is removable under said abutment face (28).
8. A plant according to at least one of claims 3 to 6, characterized in that the knife (30) in at least one of the slicing devices (14 a-g) is replaceable by a dummy plate forming a flat side conjointly with the abutment face (28).

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