EP0097794A1 - Method of and apparatus for producing a veneer strip - Google Patents

Abstract

The invention relates to a method for manufacturing a veneer web composed of individual veneer strips of finite length and width which are pre-cut from a peeled veneer sheet. According to a known method, the strips are cut from the veneer sheet in random sizes, depending on the presence of faults or quality variations of the veneer sheet, whereupon they are combined in a tesselated pattern. An object of the invention is the provision of a method permitting veneer webs of practically any desired width and length to be produced in an economical manner with optimum utilization of the faultless and acceptable-quality portions of the peeled starting veneer material. To attain this object, the invention provides that the peeled veneer is cut to strips of equal width, that the absolutely non-usable strips are discarded, that the usable longitudinal sections of partially usable strips are trimmed of such strips, that the fault-free strips and the fault-free strip sections are joined to form continuous ribbons, and finally that these ribbons are joined transversely of their longitudinal direction to form a veneer web of a desired length and width.

Description

The invention relates to a method of the type specified in the preamble of claim 1 and a device which is particularly suitable for carrying out the method.

From the practice around "veneers, plywood and blockboard", author Kollmann, published in 1962 by Springer-Verlag, Terfahren are known, in which the useless surface areas are cut out and the qualitatively different surface areas are also cut into individual veneer strips with extensive use of human labor from the original veneer be divided. This creates strips of different widths as well as veneer parts with fixed widths that have a defined relationship to the end product, eg full widths, half widths, thirds widths, etc. Some of the strips of different widths contain useless areas that have to be separated. The resulting cuts have to be cut to standard lengths, since they are of different widths and are therefore initially unsuitable for assembly in the longitudinal direction, which precludes optimal use of the veneer surface offered. The veneer strips of the same length resulting from the cuts are first assembled transversely to the fiber direction by a known method and then cut into equal widths. Only now are they suitable for assembly in the longitudinal direction by a known method and can then be divided into the length corresponding to the end product. These processes are difficult to automate due to the non-uniformity of the veneer parts. The yield of usable veneer surface is not optimal due to the necessity to limit the length of the cuts.

A further qualitative problem in the known processes is the above-mentioned fixed widths. Because of the uneven wood structure, these naturally contain areas of higher and lower quality in many pieces. The share of low quality in a larger piece devalues the whole piece and assigns it to this lower quality. Saving the higher quality portion for this higher quality would mean that the piece would have to be broken down into strips, which is avoided as much as possible because of the high workload associated with strip processing according to previous methods. The result is that the companies suffer almost constantly from a lack of higher quality, while lower qualities are available in large areas and put a strain on the warehouses used for other purposes.

In a further method described in volume 11/1980, pp. 902-904 and 909 of the magazine "Wood and plastics processing, it is proposed that the different widths of veneer obtained from raw wood blocks, which are relatively short in the fiber direction by means of error cutting, are first endlessly assembled in the transverse direction, then to divide into veneer sheets of the same width, to assemble these veneer sheets endlessly in the longitudinal direction, then to bring them to the same length in the longitudinal direction and, if necessary, to reassemble them endlessly in the transverse direction, apart from the fact that the problem of optimal use of wood is also only incompletely solved with this process Because no use is specified for veneers shorter than the peeling block length, considerable qualitative concerns must be expressed here, because the longitudinal composition of relatively large veneer widths naturally leads to a weakening of the end product over large width fractions, which makes the end usable restricted products. Finally, the degree of automatability is considerably restricted in this method because of the different output widths.

The invention is based on the object of specifying a method of the type mentioned at the outset and a device suitable for carrying out the method, with which veneer webs can be produced quickly and economically in any length and width while making maximum use of the raw veneer.

The object is achieved according to the invention by the method specified in the characterizing part of the main claim.

As a result of the always the same strip width of the strips intended for further use, the method can be carried out simply automatically and with the least possible use of labor. On the other hand, there is the possibility of creating any veneer lengths or veneer web widths depending on the quality and exclusively limited by the dimensions of the devices used for the method. It is also particularly advantageous that the veneers used as starting products are optimally used with the method according to the invention, ie that only those surface areas which are not usable for veneer webs are actually thrown away. The degree of utilization of the surface of the veneer sheets can be regulated in a wide range by the choice of the width of the strips and also by the determination of the practically usable minimum length. Claim 2 shows an advantageous embodiment. In this sorting step, there are only strips and strip sections that are practically usable and may differ only in terms of their quality and other characteristics. Sorting according to these identifiers can be carried out much more easily than was previously the case, since material units of exactly the same width are present here, which on the one hand simplify quality detection and on the other hand facilitate the correct movement and automatic control of the material movement.

Another important aspect that is incorporated into the method according to the invention can be seen from claim 3. With these provisions, not only can the degree of utilization of the raw wood be predetermined, but there is also an individual adaptability to the respective type of wood that is processed according to the invention.

An alternative embodiment variant of the method according to the invention is explained in claim 4. Thereafter, veneer that is usable and qualitatively equivalent over larger surface areas is not first divided into the strips and then reassembled. Rather, these equivalent larger veneer web parts can be cut to full or partial widths and assembled with the equally wide strips to form a veneer web of any width, the latter strips being produced according to the criteria characterized in the main claim.

Another useful point of view is evident from claim 5. Here, for example, it is contemplated that strips of different lengths, which can originate from warehousing, are of the same width and have the same quality properties, are put together to form the veneer web. The joining together is not a problem here, since the strips are provided with parallel and rectilinear edge edges, which result in the method according to the invention.

Another important thought is included in claim 6. This opens up the possibility that veneer strips composed of usable and qualitatively assessed strip sections in the longitudinal direction are combined with long strips which are inherently usable from the start and are therefore not assembled in the longitudinal direction to form a veneer web of any width and the original length.

A number of differently configured machine configurations are conceivable for carrying out the method according to the invention, of which the needs described in claim 7 should correspond particularly well to practice. The individual process steps are carried out continuously on the starting product and the intermediate products, which results in an imperative material flow and a high processing speed. The individual device components can be arranged behind or next to one another in the manner of a production line, so that the available space is optimally used.

So that veneer webs of different but constant quality can also be produced, it is expedient to supplement the device according to claim 7 by a device according to claim ⁸ .

The method according to the invention is explained below with reference to the drawings.

• Fig.la bis 1c eine schematisch dargestellte Schälfurnierbahn, die in Andeutung der weiteren Verarbeitung zeichnerisch nach Art eines Rasters so aufgeteilt ist, wie sie bearbeitet werden soll,
• Fig.2 einen nach dem Verfahren hengestellten Teil einer Furnierbahn,
• Fig.3 einen Teil einer Furnierbahn, anhand dessen eine Ausführungsvariante erkennbar ist,
• Fig.4 einen Teil einer Furnierbahn, anhand dessen eine weitere Ausführungsvariante erkennbar ist,
• Fig.5 eine schematische-Darstellung einer zur Durchführung des Verfahrens geeigneten Vorrichtung in einer Draufsicht.

Show it:

• Fig.la to 1c a schematically illustrated peeling veneer web, which is indicated in the drawing as a grid pattern in the manner of further processing, as it is to be processed,
• 2 shows a part of a veneer web produced according to the method,
• 3 shows a part of a veneer sheet by means of which an embodiment variant can be recognized,
• 4 shows a part of a veneer sheet by means of which a further embodiment variant can be recognized,
• 5 shows a schematic representation of a device suitable for carrying out the method in a plan view.

1a to 1c, a peeled veneer web 5 obtained from a round wood block by round peeling can be seen, which is divided into three sections in the drawing, although the peeled veneer web 5 is continuously produced.

It has imaginary margins 1,2. With dividing lines 3 running approximately in the fiber direction, 5 strips of the same width are cut out of the peeled veneer web. The across to the fiber direction and at the same distance lines 4 indicate a cross-raster Tei development, within which a veneer division across the fiber direction is possible.

The peeling process, starting in Fig.1a, initially provides individual, misshapen veneer pieces, which gradually increase in size with each peeling revolution, into an increasingly complete veneer belt. At the end of the peeling process, Fig.1c, the veneer sheet 5 approaches the core area of the log section, where serious veneer defects 6, e.g. wide cracks and large knotholes occur increasingly.

According to the invention, the veneer web 5 and also its individual pieces are now formed into individual strips of equal width with a width corresponding to the spacing between the separating lines 3 by cuts made approximately parallel to the fiber direction. This results in three categories of strips, namely strips Sa with full length in the direction of the fibers, strips Sb which do not cover the entire surface, but in which a certain longitudinal section is still practically usable, and strips Sc which have no practically usable longitudinal sections over their entire length. In the grid shown, a certain length unit, represented for example by the distance between five lines 4, is now selected as the length which still results in a practically usable longitudinal strip section Sd. Strip sections Sd are then cut from all strips Sb, the common feature of which is rectangular areas of the same width and at least the length Sd. The strips Sc, like the non-usable residues of the strips Sb, can be comminuted and excreted in the cross pattern. As an alternative, the crushing in the cross grid can also be omitted, that is to say the separation in the size that arises.

This leaves only strips Sa and strip sections Sd, all of which are practically usable, although according to FIGS. 1 to 1c no distinction is made with regard to quality, color or fiber structure. In practice, however, there are differences which make it necessary to sort them, so that several groups of different quality are then formed from the strips Sa and the strip sections Sd. 1a to 1c, the differences of the stripes, with the exception of the quality differences, are indicated by different hatching. Areas that remain free represent usable veneer. Obliquely hatched areas are strip parts Sc that contain no usable veneer at all, cross-divided surface areas represent parts of the strips Sb that either do not have full parallel cut edges or that are too small and less than the length of the strip sections Sd Would give length.

The above-mentioned processing method for peeled veneer web ₅ is only based on the device indicated in FIG. ₅ , which is one of several possible. Arrangements represents, explained in detail.

In the device, the preferably dried raw veneer 5, preferably obtained in a round peeling process, is fed to a cutting device 25, which breaks the raw veneer 5 into strips Sa, Sb and Sc approximately parallel to the fiber direction. This can be done at a uniformly low veneer feed rate by a stationary device that works in a clocked manner or at a higher feed rate by a sub-device that moves during the sub-process. But a step-by-step, precisely controlled veneer feed is also possible with a stationary part device.

The separation of the strip elements is expediently connected to the sub-process by establishing equal distances between them, so that the strips lie on the subsequent transport device 7. The following recognition device 8 recognizes which strips belong to category Sa and can thus be passed on unprocessed, which must be trimmed as category Sb in which area and which have no parallel edges of sufficient length so that they are addressed as category Sc = waste. The detection device 8 makes its determinations in a manner known per se, stores them and solves them in the subsequent separation and comminution system 9, which e.g. appropriate control signals from saws, circular knives or the like, which can be swiveled in and out in a narrow grid, but can also consist of high-energy beams. It is conceivable that all non-usable parts are broken down into pieces as small as the grid allows. Then it should be expedient to immediately remove all of the waste in the separation and comminution system 9, because the further transport of such small pieces is not without problems. However, it is also possible to address in the trembling and comminution system 9 only the separating elements required for separating usable and non-usable veneer parts, ie none at all in the case of SC parts. Then all parts are first transported out of the separation and comminution system 9 and into a separation device 10, the switches of which can be controlled by the detection device 8.

After the waste has been removed, there are only usable veneer parts of the same width in the categories Sa and Sd. Now, in the majority of practical cases, a qualitative selection would take place, which is not shown in FIG. 5, because this would make it unnecessarily complicated. The qualitative selection can be done manually as well as with Can be carried out and controlled using a number of known automatic detection methods. In a technically high-quality solution, it can be combined with the separation of the categories Sa and Sd in the separating devices 11 for Sd and 12 for Sa, which is again shown schematically.

Practical operation will in most cases now require intermediate storage of strips Sa and strip sections Sd separately according to quality. In Figure 5, the depiction of the magazine was also omitted. Rather, an immediate further processing to a veneer web 16 according to the invention was shown, the fiber length of which is considerably greater than the fiber length of the raw veneer 5. The qualitatively collected strip sections Sd and strips Sa are each fed to longitudinal assembly devices 13, in which they are initially fed in in a manner known per se theoretically endless veneer tapes of the same width are assembled and then divided into the new length adapted to the end product. According to the invention, there are the possibilities either to assemble the categories Sa and Sd individually or mixed together according to arbitrariness or system and to process them further or to re-magazine them. Also in the further processing, if strips of new length were produced separately from the categories Sa and Sd, there are also the possibilities of assembling the veneer web 16 first of all from the originally Sa category and then from originally from the Sd category, or vice versa, as well as the elements to be mixed according to arbitrary or system. The latter principle was shown in Fig.5.

The devices 14 each contain a stock of strips of new length, which were obtained from the categories Sa and Sd, respectively, and which they pass on here - in random order - to the transport device underneath. This feeds the strips of new length - if necessary after appropriate edge preparation, which may also have already been carried out in the longitudinal composing devices 13 - to the cross-assembling system 15, where the elements are assembled in a known manner to form the veneer web 16 and then either wound up endlessly, processed endlessly or but - as shown - can be divided into veneer sheets with a width dependent on the end product using the dividing device 17 and collected as a veneer stack 18.

The individual device components are automatically controlled by a control device 19 which is connected to the individual components via connecting lines.

The device can easily be designed so that the area of the raw veneer recognizable from Fig.lb, in which there are almost only fully usable surface areas, is divided into individual broad parts, which may already correspond to the final width of the end product.

• FIG. 2 shows, for example, the part of a veneer web cut to the finished width with a certain length and width, which is made in some areas from strips of new length produced separately for each category Sa and Sd, this new length being substantially greater than the original raw veneer length Sa.
• 3 shows a further method variant, in which case the part of a veneer web cut to the finished width corresponds in the fiber direction to the original raw veneer length Sa. The veneer sheet is supplemented in this case by parts of the Sd category assembled in length Sa.
• Finally, FIG. 4 shows, as a variant according to the invention, a part of a veneer web cut to the finished width, in which a large part width (here half width) was combined with strips Sa and strips composed of parts Sd.

Claims (8)

1. A process for producing a veneer sheet by joining individual veneer strips of limited length and width, which are cut out of veneer depending on defects and quality differences, characterized by the following steps: a) dividing the preferably dried raw veneer into strips of exactly the same width approximately parallel to the direction of the fibers, b) separating the non-usable longitudinal sections from those strips that over their longitudinal stretching sometimes have impermissible defects, creating strip sections with a practically usable minimum length, c) Elimination of those strips which have no practically usable parts and those unusable strip parts which have been separated from the usable strip sections, d) assembling the usable strip sections and possibly also the usable full length strips in the longitudinal direction of the strips to form endless strips and dividing them into any desired strip lengths as well e) assembling the strips obtained theoretically of any length transverse to their longitudinal direction to the veneer web of any length and width. 2. The method according to claim 1, characterized. characterized in that separate groups of different quality and / or coloring and / or defect structure are formed from the useful strips and the useful strip sections, and that endless bands of different quality and / or coloring and / or defect structure are formed from each group. 3. The method according to claims 1 and 2, dadurc _h ^g ekennzeichnet that the strip width of all strips and the minimum length of the defect-free strip portions, depending on the wood species and / or species-specific defects characteristic can be selected. 4. The method according to claims 1 to 3, characterized in that the strips cut to length transversely to their longitudinal direction with usable veneers of this length, but greater width than that which have the strips of the same width, are joined to a veneer web of any width. 5. The method according to claims 1 to 3, characterized in that veneer strips of the same width and different length, which were not taken from a uniform block of raw wood, are assembled to veneer strips of the same length and then to a veneer web of any width. 6. Process according to claims 1 to 3, characterized in that given the full length of the usable veneer strips given by the length of the raw wood block, these are joined together with strips of the same length from strip sections joined together in the longitudinal direction to form a veneer web of any width. 7. Device for performing the method according to claims 1 to 6, characterized - by a raw veneer cutting device (26) for the stripe categories (Sa, Sb, Sc) in exactly the same width, by a separating device (7) for producing equal distances between the strips obtained, by a recognition device (8) for determining the category (Sc) of each strip, - by a separation and comminution system (9) for separating unusable strip parts from usable strip sections (Sd) and for comminuting separate strip parts, by a separating device (10) for the comminuted parts and by further separating devices (11 and 12) in which the full-length strips (Sa) are collected separately from the strip sections (Sd), by one or more longitudinal assembly devices (13) in which the strip sections (Sd) and possibly also the strips (Sa) can first be assembled into veneer strips which are endless in the fiber direction and can then be subdivided into any individual lengths adapted to the end use, - By a cross-assembling system (15), in which the newly obtained individual lengths transversely to the fiber direction are first endlessly assembled and then broken down by a cutting device (17) into veneer layers of any width adapted to the end use. 8. The device according to claim 7, characterized - By means of a further detection device for ascertaining qualitative differences between the strips (Sa) or strip sections (Sd), with which corresponding control signals can be triggered and transmitted to further separating and collecting devices in which strips and strip sections of the same quality level can be summarized separately.

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