CA2109763A1

CA2109763A1 - Method and apparatus for the production of sheets of fibrous material to imitate a porous structure of natural wood

Info

Publication number: CA2109763A1
Application number: CA002109763A
Authority: CA
Inventors: Giovanna Senzani
Original assignee: Individual
Current assignee: Alpi SpA
Priority date: 1992-11-27
Filing date: 1993-11-23
Publication date: 1994-05-28
Also published as: DE4339515A1; ITMI922732A0; ITMI922732A1; IT1255974B; MX9307426A

Abstract

METHOD AND APPARATUS FOR THE PRODUCTION OF SHEETS OF
FIBROUS MATERIAL TO IMITATE A POROUS STRUCTURE OF
NATURAL WOOD
Abstract of the Disclosure A method and apparatus for the production of sheets of material to imitate a porous structure of natural wood. According to the invention, the porous structure of a sample surface of a sheet of natural wood is analysed, taking information from it regarding the coordinates of characteristic points of the lines representing the individual pores. Said information is then stored in a process logic unit comprising a computerised design program, providing data which indicate the dimensions of the pores to be formed. The data and information are then converted into control signals for a computerised engraving system which reproduces this porous structure by engraving it on a sheet of fibrous material. The sheet of porous material made in this way can be used directly for facing or decoration or for creating an artificial veneer.

Description

2 21~97~3 ':';

Background of the Present Invention The present invention relates to a method and to an apparatus for working sheets of wood or of fibrous material having a porous structure which is especially suitable for producing veneers of artificial wood. More particularly the invention relates to a method which enables the porous structure of any type of natural wcod to be recreated artificially, starting with common wood of poorer quality in order to produce veneers or for other purposes of use of natural wood.

Various methods have been proposed in the prior art for the production of sheets of wood veneer imitating natural wood. The first attempts involved the formation of suitable blocks by superimposing and glueing laminates of wood obtained by tangentially slicing a log. The block was shaped appropriately in a press, superimposed and glued to other identical blocks until a final block was obtained from which sheets of wood veneer were then cut, according to predetermined cutting angles. The shape of the block, slant of the cutting angle, dyeing of the sheets and the possible use of coloured glues, enabled the grains and porosity of wood to bs imitated to a certain extent~ In practice the structure of the veneer remained substantially similar to the wood structure of the sheets of material used for forming blocks.

This technique is described for example in the patents US 3 312 582 andUS 3 418195.

3 2 1 9 9 7 6 3 ::

Methods of this kind provided a fairly rough imitation both of the grains and of the porous structure of natural wood. The level of commercial success was hence very low in relation to the obviously artificial appearance of the individual sheets of veneer, apparent even to a non-skilled in the art. The method was moreover extremely complex, with negligible aesthetic results, which were not always totally repeatable.

Other methods were also proposed which involved the formation of blocks by means of a different combination and superimposing of different wood sheets or of laminates, some of whose fibres were orientated perpendicular to the plane of the sheets themselves. By means of an appropriate composition of the blocks and their configuration in the moulds, it was possible to place in the required positions layers with fibres orientated in various ways, longitudinally and perpendicular to the sheets of veneer cut from the block itself, in this way achieving a better imitation of a wood structure reproducing the various layers of growth of a natural trunk.

Although these systems have given good results, they nevertheless provide a porous structure of the veneer sheets whose appearance is not entirely natural in that layers with fibres orientated perpendicular to tha plane of the sheet itself alternate in the reconstructed block, contrarily to the longitudinal direction of the fibres in a natural trunk. Moreover there is no possibility of controlling the shape, arrangement or dimension of the individual pores or of modifying these characteristics according to the , '.

4 210~763 varying production needs in order to obtain the porous structure of the type of wood to be imitated.

Finally the process of reconstructing the block from which the final veneer is to be cut is still relatively complex and complicated.
.
The object of the present invention is to provide a method for the formation of sheets of fibrous material which have a porous structure of any type whatsoever of natural wood, which can be obtained in a repeatable and perfectly controlled manner.

More particularly the object of the present invention is to provide a method for the formation of porous structures on sheets of fibrous material, as a perfect imitation of the porous structures of natural wood, by means of which the fibres of the individual sheets can be maintained parallel in the natural planes wherein they lie, at the same time achieving an imitation of whatsoever porous structure so as to improve the quality of the veneer which can be obtained in this way to a considerable extent.

Yet a further object of the present invention is to provide a method and apparatus as defined above, which not only allow high quality results to be achieved when imitating any type of wood, but at the sama time allow a high degree of control of the production process, and repeatability, continuity and reliability of the result achieved.

5 2:1a9753 Summary of the Invention The above can be obtained by means of a method for the formation of porous structures in sheets of fibrous material to imitate porous structures of natural wood, according to the features of the main claim. - ~;

According to the invention, a portion of a sample surface of a porous ;;
structure of a natural wood to be reproduced is analysed, taking note of information relating to the shape and coordinates of characteristic points ;~
of the lines defining the shape of the individual pores. Said information is stored in a process iogic unit comprising a computerised design program, and at the same time data are provided to indicate the dimensions of the pores. The data and information stored in this way are then converted ~ ~ ;
into control signals for a computerised engraving system, which reproduces the memorised porous structure of the sheet of natural wood, engraving it continuously or discontinuously on fibrous material in sheets or in the form of a strip, which can be used later in the preparation of artificial veneers according to systems in themselves known, for example from the prior documents previously mentioned. ~ :

Brief Description of th~Drawings These and further features of the method and apparatus according ta the present invention are to be illustrated in greater detail hereinunder with reference to the examples in the accompanying drawings, in which~
Fig. 1 represents a process diagram according to a possible embodiment n of the present invention; -6 21097~3 Fig. 2 is a plan view of an enlarged detail of a sheet of natural wood,whose porosity must be imitated by operating according to the process diagram in figure 1;
Fig. 3 is a plan view of a further enlarged detail of a pore of the porous structure of figure 2; ~ .
Fig. 4 is a sectional view of the pore taken along line 4-4 of figure 3;
Fig. 5 is a sectional view of the pore taken along line 5-5 of figure 3;
Fig. 6 is a plan view of a sheet of fibrous material on which the fibrous structure of the wood type to be imitated has been reproduced, according to the method of the invention;
Fig. 7 is a plan view of a sheet of fibrous material on which a fibrous strcture of a wood has been reproduced according to a variant of the ~nethod according to the invention.

Detailed Description of the Invention With reference to figure 1, A denotes a sheet of natural wood of a generical wood type whose porous structure is to be imitated for the production of an artifical veneer.

As can be seen in the same figure 1, and in the detail in figure 2 which represents an enlarged view of a portion of surface B of the sheet of natural wood A, the fibrous structure of the latter has, in the example shown, zones B1 having a very compact fibrous structure, with few pores, alternating with zones B2 having a high degree of porosity, according to the wood layers belonging to the various periods of growth of a natural "''`"'`'- '~'.`..' ,`

7 2 1 ~ 9 7 6 3 trunk.

After having isolated a portion C of a sample surface of a porous zone B2, whose fibrous structure must be reproduced and used to achieve a .
perfect imitation of the similar porous structure of the natural wood, a determination is carried out of the positions and coordinates of characteristic points of the lines representing individual pores P in relation to specific reference cartesian axes, storing these data and information in a process logic unit or microprocessor 10, indicated schematically in -~
figure 1 .

This can be achieved for example by analysing the porosity of the sample surface C by means of a scanner, or directly by an operator who uses for example a pen for writing 11 or by another suitable manner. -During the manual or automatic scanning of the individual pores P of the portion of sample surface C, all the information required for defining the position and distribution of the individual pores is obtained by means of the coordinates of the various points or characteristic points which form the lines representing the pores themselves.

These data are then stored in the data memory of the process logic unit - . .
10, into whose main memory a suitable computerised design program (CAD) has been loaded previously and which is appropriate for this ~ ~:
purpose. ~ ~ "

8 21097~3 Since each pore P, as shown in figures 3, 4 and 5, is characterised, inaddition to its shape and position, also by its length L1, width L2 and depth L3 which can be constant or vary, by means of the control keyboard or another device, for example a mouse 12, the operator enters into the memory of the microprocessor 10 all those necessary data which indicate the real dimensions of the pores to be reproduced, with the possibility of adapting them or changing them. Thus an image will gradually be created on the screen of the porous structure to be formed, which may be adjusted or modified from time to time until a perfect imitation of the natural one is obtained.

Onca the process unit 10 has stored and processed, on the basis of its design program, the information and data relating to all the pores of the sample of area C analysed, these data must be converted into signals suitabls for the functioning of a computerised engraving system. This conversion may ba performed directly by the same process logic unit 10 if appropriate circuits are provided or, as indicated schematically in figure 1, it can be performed by a second process logic unit 13 provided with a control keyboard 14, connected directly and serially to the process unit 10, as indicated by the dotted line 15, or by means of a suitable magnetic medium 16 indicatedschematically. !

The conversion of these data into signals for controlling the computerised engraving system may be controlled or modified if required by varying appropnate working parameters in the second process unit (CAM) for 9 2 1 0 ~ 7 6 3 controlling the apparatus. Therefore the signals in output from the process unit 13, by means of a suitable interface 17, are sent to the computerised engraving system 18 to reproduce in a unique or repeatable manner on the sheet of material C1 of a different wood type, of poorer quality, the same porous structure of the sample of surface C of the wood structure of the type which is to be imitated.
: `
The sheets C1 with the engraved porous structure may then be used in a normal process of forming blocks for the production of an artificial veneer, in a manner in itself known. Engraving of the pores (continuously or discontinuously) may be carried out at any point of the process of producing the vsneer, for example immediately after the tangential slicing or the radially cutting of the log and before possible dyeing, or subsequent to the phase of dyeing which precedes the formation of the block from which the new veneer will in the end be cut.

. . ;.:
The engraving of the porous structure on the sheet C1 can be performed ~ m using any computerised engraving system, be it mechanical or of another kind. For example tests carried out have shown that it is extremely advantageous, in terms of reliability and rapidity of execution, to use engraving systems which adopt sources of highly concentrated light energy in order to generate pulses of variable intensity and duration, such as to produce localised combustion of the fibrous material in order to achieve engraving of the sheet, faithfully copying and reproducing the effect of porosity of the original sample according to the processing ~ ~;

:~

2i 09 ~63 performed by the process logic units 10 and/or 13 mentioned previously.
By way of an example, good results have been achieved by using devices capable of generating and strongly amplifying radiations of optical frequency, of the stimulated radiation emission type. By choosing appropriate optical frequencies of operation and the frequencies of . ~.
emission of the pulses of light energy, it is possible to achieve excellent results for any type of wood to be imitated. Therefore the process logic unit 13 must control the energy generator 19 and the actuator or actuators 20 which direct and control the ray for engraving the porous structure on the sheet C1. Figure 6 in the drawings shows the final result on the sheet C1.

By following the procedure described above, it is therefore possible toanalyse a whole series of samples of porosity of the same type of wood ancUor different wood types, storing them in one of the process units or on appropriate magnetic media which may be used from time to time according to production needs. In every case a method and apparatus will be provided for the formation of porous structures in sheets or strips of fibrous material, which will enable any porous structure of natural wood to be imitated to perfection, always maintaining a longitudinal arrangement of the pores in substantially tangential planes in'the reconstruction of a hypothetical trunk of wood from which an artificial veneer is subsequently cut.

The method according to the invention therefore enables a greater 11 2.L~9763 degree of approximation to be achieved in the imitation of a veneer of natural wood, maintaining control and a high degree of reliability in the production process, with the possibility of adapting the method for producing porous structures, however configured, directly on rotary-cut wood, or on veneers forming the end product. This is shown by way of an example in figure 7, where a porous structure F with a design of the various grains of the wood has been reproduced on a generical sheet of wood E. This can be achieved for example by combining data and information of a sample of porosity of a type of wood previously stored in the memory, with a particular grain design to imitate a specific type of wood, specially created or copied from a sample of natural veneer.
~ - .
The intention therefore is that the general principle of the present invention consists in reproducing by engraving porous structures of natural wood on sheets of fibrous material of another kind, which can be used in the production of artificial veneers with an improved appearance.
Therefore what has been said and shown has been given merely as an illustration of the innovative principle which is claimed.

.: :

Claims

1.- Method for the formation of porous structures on a fibrous material, to imitate a porous structure of natural wood, in particular for the production of artificial veneers, comprising the steps of:
- analysing the porous structure of a sample surface of the natural wood to be imitated, noting data and information relating to the arrangement and to the coordinates of characteristic points of the lines defining the individual pores of the porous structure in question;
- storing said data and said information in a process logic unit provided with a computerised design program (CAD), also providing data indicating the dimensions of the pores themselves;
- converting said data and said information into control signals for a computerised engraving system; and - reproducing said porous structure, stored in the memory, on a sheet or strip of fibrous material, engraving it by means of said computerised engraving system.

2. - Method according to claim 1, in which during storing of the porous structure in said process logic unit the data relating to the dimensions of length, width and depth of engraving of the individual pores or shape of the pores themselves are provided and/or modified.

3.- Method according to claim 1, in which engraving of the pores is achieved by means of a sequence of pulses of highly concentrated light energy, for example by stimulated radiation emission.

4.- Method according to claim 1, in which engraving of said porous structure on a sheet or strip of fibrous material occurs continuously and/or in predetermined zones or bands of engraving.

5.- Method according to claim 1, in which the data converted into control signals are transferred into a second logic unit for controlling the computerised engraving system.

6.- Method according to claim 5, in which said second control logic unit is connected to the first process logic unit serially or by means of transferable magnetic memory media.

7.- Sheets material for the production of artificial veneers, having a porous structure engraved to imitate a corresponding porous structure of a type of natural wood, in which the pores are engraved by means of the method of any one of claims 1 to 6.

8. - - Sheet material according to claim 7, in which the engraving of the porous structure is distributed over the whole surface of the sheet or part thereof evenly or according to a predetermined design.

9. - Method for the formation of porous structures on fibrous material in the production of artificial veneer whereby blocks of precomposed wood from which the veneer sheets cut are formed by superimposing and alternating sheet materials, suitably glued and/or dyed, in which at least part of the sheets of material have a porous structure imitating that of the natural wood to be imitated, achieved by means of the computerised -engraving method set out in the previous claims.

10. - Method according to claim 9, in which said computerised engraving is performed before the phase of dyeing the sheets continuously during tangential slicing of a log or by radial cutting, before or after the phase of dyeing the sheets respectively or in another phase of the process of forming a composite block for the production of artificial veneer.

11. - Apparatus for the production of material in sheets with a porous structure achieved by means of the method of the previous claims, in which it comprises means for analysing a sample porous structure of a type of wood to be imitated, means for storing and reconstructing said porous structure in a process logic unit equipped with a computerised design program- (CAD) and means for converting said data into control signals, as well as comprising a computerised engraving system fed by the abovementioned control signals.

12.- Apparatus according to claim 11, in which said computerised engraving system comprises a source of highly concentrated light energy, with stimulated radiation emission, and means for directing and orientating a light ray coming from said source of energy towards a sheet material to be engraved, according to the control signals emitted on the basis of an engraving program stored in a control logic unit of the light energy source, and means respectively for directing and orientating the light ray for engraving the material.