CA1210682A - Plywood and method of manufacturing the same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Glued laminated wood which has a novel laminated structure and may be fabricated from small-sized veneer sheets, and method of manufacturing such laminated wood are provided. The glued laminated wood in its continuous form is made from a series of unit-length veneer sheets each having the same length and thickness which are lamina-ted in a laid-up arrangement in which each of the veneer sheets is lapped on another and offset therefrom in the direction of its length at a regular interval determined by the number of plies to be in the laminated wood products and the length of the unit veneer sheets. It has a novel structure in that each veneer sheet therein has tandemly spaced straight length portions which are parallel to each other, but successively displaced from each other in the direction of the thickness of the product, there being a somewhat S-shaped curved length portion of the veneer sheet between any successive pair of these straight length portions.
The number of such straight length portions in each unit veneer sheet is equal to the number of plies in the glued laminated wood being made, and the length of each such straight length portion is nominally determined by dividing the length of the unit veneer sheet by the number of plies.

Description

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GLUED LAMINATED WOOD AND METHOD OF MANUFACl'URING
T~IE SAME.
Fiel~ of the invention The present invention relates generally to yluea laminated wood, including plywood and to a method of manu-facturing the same. More specifically, it re]ates to glued laminated wood having a novel laminated structure of veneers and to a method of manufacturing the same.
Background of the invention In the so-called improved woods, several types of sheet or board materials are available, among which glued laminated wood, including plywood is one of the most popular wood sheet materials.
In general, glued laminated wood which is composed of plural layers of veneers laminated or glued together into a sheet form achieves its thickness from the thicknesses of the individual component veneers and the number of layers of such component veneers. Such glued laminated wood, including plywood, as compared with sawn lumber, exhibits improved uniformity in strength and provides a useful wood sheet material which can be made in much larger areas.
Therefore, such glued laminated wood, including plywood comes in a great variety of sizes and thicknesses, and can be laminated in different ways to meet varying requirements of the marke~. It is therefore used for a wide range of applications including, construction, housing, furniture, e-tc.
Under present circumstances of limited supply and ;82 therefore increasing prlces of logs, it is an uryent task of every manufacturer to establish a manufacturing system which can permit production of various kinds of glued la-minated wood sheets or panels having different lengths, widths and thicknesses with the highest possible yield rate and the minimum cost in production, labor and materials, in order to fulfill the above-said versatile demands of -the market. In addition, it is a potential task of the producer to develop new fields of application for such glued lamina-ted wood through further improvements of its inherent advan-tages.
It is evident that the above~mentioned urgent pro-blems cannot be solved by glued laminated wood having con-ventional structure which inevitably calls for and requires selection of component veneers whose sizes are determined by the si~es of the glued laminated wood sheets or panels to be mada. For e~ample/ it is presently necessary to cut veneer sheets from a log which is eight feet long in order to make a typical 4' x 8' plywood panel, for reasons under-stood by those familiar with the manufacture of plywood.
This requirement makes conventional plywood panels more costly.
~t is therefore believed that an effective approach to the problem would be -to establish a technology by which various sizes of glued laminated wood, including plywood may be fabricated from veneers of a reduce~ number of sizes or, most preferably, from veneers of only one size. Moreover, it would be a significant advance if glued laminated wood panels could be manufactured fr~m veneers which are smaller ~Ji ~LZ~

than the intended panel si~e. ~n other words, the pre-sent invention is intended to provide more effective utilization of veneers. This is because, iTI the manufac-ture of glued laminatecl wood, the process involved in makiny veneers from logs is more problema~i.c and calls for more labor than does the process of making the lami-nated wood from the veneers. ~hus, improvements in the former process can make a greater contribution to the reduction of costs and to the simplification of laminated 1~ wood manufacturing as a whole~ However, when realizing a plywood technolog~ which could make possible production of various plywood sizes from veneers of a reduced nu~er of veneer sizes or of a single size, it would be important to prevent the introduction of any new defects in the pro-1~ ducts which would be made in that way. The glued laminated wood and the method for its manufacture according to the present invention were developed with these considerations n mind.
Japanese Patent Application No. 104006 (1976~ pu-blished on September 14~ 1976 to Ishida shows glued lami-nated wood composed of a series of short veneers which are all parallel-laminated in such an arrangement that each.veneer is offset or shifted with respect to its ad-~acent veneer at a regular interval of leng-th, and the

2~ ends of all of the veeners are exposed on both faces of the sheet. However, the glued laminated wood product o-f the present invention is different, and is produced in a different way.

-~ _ 4 -~t is an object oE the present invention to provi-de glued laminated wood which has improved ven~er lamina-tion and is economical to manufacture.
~t is another object of the invention to provide S glued laminated wood which, when its length and width are given, can be made from veneers whose lengths and/or widths are smaller than those of the glued laminated wood to be made.
It is another object of the invention to provide glued laminated wood which can be made longer without being influenced by the given length and/or width of the veneers therefor.
It is still another object of the invention to pro vide glued laminated wood which can be made in many sizes or dimensions from veneers whose number of sizes or dimen-sions is reduced.
It is still another object of the invention to pro-vide glued laminated wood which can be made in various forms of veneer lamination.
It is still another ob~ect of the invention to pro-vide glued laminated wood which, after forming, is accep-tahle in appearance and can be used without further pro-cessing.
It is another important object of the present in-~5 vention to pro~ide a method of manufacturing the glued laminated wood product contemplated by the invention.
It is still another object of the invention to pro-vide a continuous method of gluing and laying-up of veneers ~, in making oE the glued laminated wood which has distinct labor saving advantages.
BrieE d~scription o~ the Invèntion The foregoing objects are attained by providiny a continuous run of laid-up veneers which is made from S a series ot unit-length veneer sheets having the same length and laminated in a laid up arranyement in which each veneer sheet is lapped on another and offset there~
from in the direction of its length at a reyular interval determined by the number of plies to be in the glued la minated wood and the length of the unit veneer sheets.
The layers of veneers thus arranged are tacked, and glued laminated wood panels of one or more desired sizes are produced by ~utting such a continuous length of laid-up veneers into the desired lengths and then pressing the lS cut lengths to maka the exposed surfaces of the veneer sheets flush with ea~h other. Alternatively, depending upon the arrangement and the type of hot press for forming glued laminated wood, an indefinite and substantially con-tinuous length of glued laminated wood from which panels of the desired lengths may be Cllt, can be produced.
The gl~ed laminated wood, including plywood thus produced has a novel structure in that each veneer sheet therein has tandemly spaced straight length portions which are parallel to each other, but successively displaced from each other in the direction of the thickness of the glued laminated wood, there being a somewhat S-shaped curved length portion of the veneer sheet between any s~lccessive pair of these straight length portions. The ~Z~
~ 6 --extent of the referred to displacement of each successive straight length portion is equal to the thickness oE the adjacent veneer sheet, and the number of such straight length portions in each veneer sheet i5 e~ual to the number of plies or veneer laminations in the glued laminated wood being made. The length of each such straiyht length por-tion is nominally determined by dividing the length of the unit veneer sheet (measured in the direction of forma-tion of the laminated wood) by the number of plies. ~hus, the endmos~ straight length portions of each veneer sheet will respectively appear on the opposite faces of the laminated wood product and form a portion of such faces.
The unit-length veneer sheets are substantially flat when the necessary glue is applied to their overlapping length portions and they are laid-up in the afore-mentioned successively lapped relation. It is apparent that all of the veneer sheets will be inclined to the horizontal and will cxtend across the thickness of the laid-up arrangement thereof. Preferably, the unit-length veneer sheets are laid up ~ubstantially in a continuous manner, which is followed by a tacking operation for temporarily laminating the glued plies of veneer sheets together. After tacking, panels of laminated ~eneer sheets of any selected sizes are cut fro~ the continuous lamination of veneex sheets, and the individual panels are then hot-pressed to cause per-manent formation of the afore-mentioned straight length and curved length portions in each laminated veneer sheet to produce a flattened thickness in the glued laminated wood panels and also for curing the lamination glue, thereby g~

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to fix the shapes of the veneers therein.
In i~s preferred embodiment~ the invention ~urther contemplates a continuous manner of application of glue to each veneer sheet, before it is laid-upl b~ which those areas on the sheets which will appear on the faces of the glued laminated wood are automaticall~ shielded from the glue application, yet the glue is applied to all of the areas on which it is intended. This is accomplished by arranying a single row of the veneer sheets in lapped relation on a flight conveyor, preferably located above the main laying-up conve~or and which travels ln the oppo-site direction, and appl~ing the glue by a glue spreader along only the top surfaces of the lapped sheets. The unit veneer sheets with the glue thus applied are then successively dropped on~o the main conveyor in their in-tended laid-up arrangement, as will be seen.
After the glued laminated wood panels have been formed, filler material ma~ be applied to fill in the na-turall~ occurring grooves adjacent the ends of the veneer sheets to smooth one or both faces of the panel. Alter natively, a conventional panel-si2ed veneer sheet overlay may be laminated onto one or both faces, whereupon the pane~s will have the appearance of conventional panels.
Still another alternative would be to avoid the formation of such grooves by beveling one or both ends o~ each veneer sh~et before forming the laminated wood, as will be seen.
Detailed Description of Preferred Embodiments These and other objects, features and advantages of , the inven-tion will become apparent to those s~illed in the art from the following descriptlon of the basic structure of pl~wood and ~arious embodiments of ylued lamina-ted wood according to the present invention, and methods for its manufacture, which description is made with reference to the accompanying drawings, wherein:
Fig. 1 is a fragmentar~ perspective view illustra-ting the basic laminated structure of veneers as it ap-pears in glued lamina-ted wGod according to the invention;
Fig. 2 is similar to Fig. 1, illustrating the same basic laminated structure of veneers in the glued lamina-ted wood of the invention, but wherein the veneers have beveled ends for providing uninterrupted surfaces on the plywood;
Fig. 3 is a fragmentary side view of glued lamina-ted wood of the invention, showing a manner of veneerlamination which is slightly different from that of Fig.

Figs. ~ to 7 are fragmentary side views showing other possible end forms of each veneer and laid-up arran-gements of such veneers;
Fig. 8 is a partial perspective view showing a ty-pical unit veneer sheet which is used as a component ve-neer for fabricating glued laminated wood panels in accor-dance with the invention;
~S Fig. 9 is a partial perspective view showing a pa-rallel laminated wood panel according to the invention produced using unit veneer sheets as illustrated in Fig. 8;

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g Fig. 10 is similar to Fig. 9, but showing another embodiment of a parallel laminated wood panel produced using unit veneer sheets having beveled ends;
Fig. ll is a par-tial perspective view showing ano-ther unit veneer sheet which is used as a component veneerfor making glued lamina*ed wood panels;
Fig. 12 is a partial perspective view showing the embodiment of a parallel ~aminated wood panel produced using unit veneer sheets as illustrated in Fig. 11;
Fig. 13 is similar to Fig. 1~, but showing another embodiment of a paxallel laminated wood panel produced using unit veneer sheets similar -to that of Fig. 11, but having beveled ends;

Fig. 14 is a fragmentary perspective view of a unit vPneer sheet which is made using two veneer sheets jointed together;
Fig. 15 is a partial perspective view of the embo-diment of a glued laminated wood panel of the invention produced using -the unit veneer sheets as illustrated in ~Q Fig. 14, Fig. 16 is similar to Fig. 15, but showing another embodiment of a glued laminated wood panel produced using unit veneer sheets similar to that of Fig. 14,but having beveled ends;
Fig. 17 is a partial perspective view of a unit veneer sheet which is made using three pieces of veneers jointed together;
Fig. 18 is a partial perspective view showing the :. .

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embodiment of a glued laminated wood panel of the inven-tion prod~lced using unit veneer sheets as illus-trated in Fig. 17;
Fig. 19 is similar to Fig. 18, but showing another S embodiment o~ a glued laminated wood panel produced using unit veneer sheets similar to that of Fiy. 17~ but having beveled ends;
Fig. 20 is a partial perspective view showing ano-ther unit veneer sheet which is made using three pieces of veneers jointed together;
Fig. 21 is a partial perspective view showing the embodiment of a plywood panel of the invention produced using a plurality of the unit veneer sheets shown in Fig.
20;
Fig. 22 is similar to Fig. 21, but showing another embodiment of a glued laminated wood panel of the invention produced using unit veneer sheets similar to that shown in Fig. 20, but having beveled ends;
Fig. 23 (A) and (B) are partial perspective views showing res~ective, alternate grain arrangements in unit veneer sheets made of two pieces of undersized veneers ~ointed -together;
Fig. 24 is a partial perspective view of the embo-diment of a glued laminated wood panel of the invention produced by laying up alterrlate unit veneer sheets as shown in Figs. 23 (A~ and (B);
Fig. 25 is similar to Fig. 24, but showing another embodiment of a glued laminated wood panel produced in , ~

the sarne manner as that of Fig. 24, bu-t wherein the uni-t veneer sheets have beveled ends;
Fig. 26 is a schema-tic illustration o~ pr~ferred method of manu:Eacturing the aforesaid embodiments of ylued laminated wood panels, including plywood panels, accordiny to the invention;
Fig. 27 i5 an enlarged sectional view of veneers, showing possible variations in the relative lapped positions of one veneer sheet on another during the laying-up step in the glued laminated wood manufac~uting method illus-trated in Fig. 26;
Fig. 2~ is a similarly enlarged sectional view of veneers r showing possible variations in the relative lapped positions of one veneer sheet on another during the gluing step in the glued laminated wood manufacturing method il-lustrated in Fig~ ~5;
Figs. 29 and 30 are partial perspective views, res-pectively~ showing alternative types of flight conveyors which may be used to convey the unit veneer sheets during the gluying and laying-up steps in manufacturing the glued laminated wood panels according to the method illustrated in Fig. 25;
Fig. 31 is a schematic diagram illustrating the ope-rative relationships between the conveyor drives used in ~S the gluying and laying-up processes;
Fig. 32 is a fragmentary perspective view of glued laminated wood in accordance with the invention having overlay sheets adhered to its respective faces; and Fig. 33 is a diagramatic illustration o~ the manner ~J

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of cutting unit Veneer sheets ~rom random lenykh logs, for use in practicing the present invention.
Referring first to Fig. 33, thexe is illustrated a conventional manner of producing a continuous lenyth of venee.r sheet V from a log 40 by forced rotation of -the log in the direction of axrow ~, against the knife blade Y, causiny the veneer V, having a thickness t, to peel off in the direction of arrow Z. The wood grain G extenas in the direction of the length of khe log 40, as is well understood.
When making a conventional glued laminated wood panel (.not shown~, the length of the panel is limited to khe length o~ the log 40; e.g., a 4I x 8' pl~wood panel calls for a log whose length is at least 8', which means that a veneer-lathe which is capable of handling at least 8' long logs has previously been necessary for making such 4' x 8' panels. According to the present invention, how-ever, any sized panels can be produced from a plurality of unit veneer sheets, such as the unit veneer sheet 3 shown in Fig. 8 whose length is indicated b~ Ll and its width W. The width of the panel -to be made is determined by cutting the veneer V (Fig. 33) peeled from the log 40, into a width W, in this case 4'. On the other hand, since the series of ~nit veneer sheets 3 are laid~up and lamina-ted success.ively in the direction Ll (Figs. 8 and 33), the glued laminated wood panel can be made as long as any req~ired dimension, say 8'. In this way, the 4' x 8' panel can be produced from a log 40 whose length does not .! ~
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l~ve to be at least 8' ~ong, but may be much smaller than that, say only 3' long.
Turning now to Figs. 1 and 2, the basic laminated structure of venears glued toge-ther to form glued lamina-ted wood according to the present invention is illustra-ted wherein the glued laminated wood, though it is shown only in a partial view, is designated by reference nu-meral 1, and veneers constituting the layers or plies of such glued laminated wood 1 are indicated by reference numeral 2.
For clarity of understanding, no wood grain pattern is shown on th~ laminated wood product in Figs. 1 and 2.
The present invention contemplates the production of glued laminated wood, having any desired finite length, which.may be obtained from a potentially continuous length of laminated wood formed by a series of relatively small-$ized ~nit-length ve.neer sheets laminated in a regular manner so as to form such continuous length of glued la-minated wood. For convenience in describing the structure of glued laminated wood according to the pres~nt invention, the veneer lamination structure of the product will be explained herein on the assumption that the glued lamina-ted wood which is partially shown in FigsO 1 and 2 (and also in other similar drawings illustrating individual different embodiments) constitutes a fragmentary showing of either the finished, cut glued laminated wood panel or the glued laminated wood as formed in a continuously extending len~th from which the plywood panels may be cut, because the shapes of the veneer laminations are the same in both.
Referring to Fig. 1, -the glued laminated wood in accordance with the invention is formed b~ laminatiny a series of unit veneer sheets 2, each haviny the same thickness t and the same length L. In the illustrated embodiment, the~v are built up into a Eive ply of five-layer configuration, as most clearly seen at the cut-away end section of the illust~ated glued laminated wood 1.
In making the glued laminated wood, a series of such unit veneer sheets 2 are laminated tc~gether in a laid-up arran-gement so that each of the veneer sheets 2 is partl~ su-peximposed, or lapped, on another veneer sheet 2 positioned in an adjacent layer, the upper sheet being offset from the other, i.e., having its one end spaced from the cor-respondingly adjacent end of the underlying sheet, at alength interval Q Thus, the successively laid-up unit veneer sheets 2 may form an indefinite, continuous length.
Wh.en such a lai.d-up arrangement of veneer sheets 2 is pressed flat, each veneer sheet is deformed, and displaced, or stepped in the direction of the thic~ness T of the laminated wood, at the same regular intervals Q, at the locations corresponding to the ends of the successive veneer sheets. As will be seen, each succesive veneer sheet if offset from each other at the same interval Q, and it will be noted that each component veneer sheet 2 thus deformed .includes respective straight length portions la forming portions of the opposite faces of the laminated wood product, and straight length portions lb extending parallel thereto in tamdem relation and successively displaced from each o-ther in the direction of the thick~
ness T of the procluct. Between each pair o straiyht leny-th portions a generally S-shapecl, curved length portion lc is formed comrn~nsurately. A finished glued laminated wood panel having any desired length may be obtained by cutting such substantially continuous length of the laminated wood.
In the continuously extending glued laminated wood having a preselected number N of veneer plies and composed of veneer sheets 2 each having a longitudinal dimension L which are offset at length intervals Q, the relationships between N, L and Q, may be formulated such that L is substantially e~ual to the product of N and Q, i.e., L_NQ. The lapping distance or lapped leng-th portion of each veneer sheet 2 is therefore expressed as L -L/N.
In order to ensure consistency in the number of veneer plies the glued laminated wood 1 for attaining substantial uni-formity in the product thickness throughout its length~
the component veneer sheets 2 should be offset when lapped on each other at such regular intervals that the leading end 2a of any veneer sheet 2 on one face of the product and the trailing end 2_ of a veneer sheet 2 exposed on the other face thereof are positioned in oppositely aligned 2S relation to each other across ~he thickness _ of the pro-duct, as exemplified in Fig. lo Therefore, consistency in the number of veneer plies in the laminated wood 1 is assured by predetermining the value for Q correctly with ~i.
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relation to the desired number N of veneer plies and the length L of each component veneer sh~et 2 or, alter-natively, by predetermininy the value for L with re~ation to _ and ~. As a concrete e~ample, when glued laminated wood of five-ply configuration ~N=5) is to be made from veneer sheets each having a length of 300 mm (L=300), the offsetting length interval Q will be about 60 mm (or300/5).
It will now be apparent to those skilled in the art, to increase the number of veneer plies in the glued laminated wood 1, the value for L i5 increased and/or the value for Q is decreased accordingly; and that, to decrease the number of plies, the reverse is true.
In the glued laminated wood of Fig. 1 whichis com-posed of veneer sheets 2 whose ends are square-cut, re-cessed portions R will inevitably be formed extending -across the width of the product on both faces ld, l_ thereof at locations which are spaced at intervals corres-ponding to the lengths Q. Such recesses may be left as they are without any additional processing if so desired, e.g. for any particular appearance effect, although they may be easily eliminated by applying filler material therein.
Alternatively r additional grooves may be form~d so as to camouflage the original recesses.
Referring now to Fig. 2, the glued laminated wood 1 is fabricated substantially in the same manner as the glued laminated wood of Fig. 1, but the component unit veneer sheets 2 for its lamina-ted construction are provided at their ends 2a, 2_ ~ith bevels formed by scarf-cutting or ~2~

any other convenient process. The results j.s -th~t the glued laminated wood 1 made from such beveled veneer sheets will have complete fla-tness without the referred to recesses R ~Fig. 1) on both ~aces thereof. When vene~r sheets '~ having such beveled ends are used for lamina-tion, however, it is important that each sheet 2 be accurately overlapped so that the beveled faces of each pair of opposed ends 2a, 2_ on the opposite faces of the product overlap each other with reference to ~heir sectional alignment, as shown in Fig. 2, to achieve complete flatness without aither recesses or projections on the product faces. In such a case, if the length L of each component veneer sheet 2 for the glued laminated wood of Fig. 2 is the same as that of Fig. 1, the length Q of the veneer offset intervals should be slightly smaller in Fig. 2 than in the case of Fig. 1, because the membars of each pair of opposing beveled ends 2a, 2b extend beyond each other for a slight distance, as will be understood.
It should be noted here in connection with the afore-mentioned relation of Q~L/N that in the glued laminated wood of Fig. 1 each pair of the adjacently opposite ends 2a, 2_ are preferabl~ positioned with some longitudinal spacing bQing provided in the sectional alignment between the extreme ends thereof, whereas in the glued laminated wood of Fig. 2 each pair of the adjacentl~ opposite beveled ends 2a, 2b is in fully overlapping relation to each other.
Thus, the value for Q varies from case to case even if the -values for _ and N remain the same. In addition, although the length L designates the longitudinal dimension of each , -- ~z~

component veneer sheet 2 in a straiyh~ened states, the actual ~alue Eor L as measured in the longitudinal di-rection of the formed laminated wood will be sliyhtl~
smaller. Thol1gh there actually exists a slight de~iation from the relationship ~ , it will be understood, having the features of the laminated wnod structure of the inven-tion in mind, that such deviation is considered to fall within the scope of the formulation Q-L~N.
Reference is now made to Figs. 3 to 7 showing va-rious examples of the shapes of the veneer ends, and re-lative alignment relationships of the oppositely disposed respective ends 2a, 2_ on opposite faces of the laminated wood.
Referring to Fig. 3 which shows in siae elevation lS a portion of the glued laminated wood 1 having five plies of veneer shee~s 2 laminated together 7 each veneer sheet 2 has square-cut ends and is lapped on another using an offset interval such that the opposed ends 2a, 2b extend beyond each other for a slight dist~ce, with the result that o~twardly proje~ting portions are formed on both faces of the laminated wood. Of course, when the laid-up veneer sheets are pressed to deform the laminations, the faces of the press accommodate these projections, as will be understood. These projections on the laminated wood may 2~ be left as they are if so dèsired, but may be removed readily by sanding or cuttiny, as indicated by phantom lines, for prod~cing substantially flat surfaces on the product faces.

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Figs. 4 to 7 show six plies of veneer shee-ts 2, respectively, which are just laid~up and are yet to be glued together to form the complete laminated wood prod-uct.
In Fliy . ~ r each veneer sheet 2 has beveled encl~ with their beveled faces facing inwardly. ~'he ends 2at 2b are posi-tioned in overlapping relation as illustrated, so that their beveled faces extend beyond and face each other~
Glued laminated wood obtained by pressing these six plies of veneer sheets 2 to cause the aforementioned deformation 1~ thereof is similar to the glued laminated wood of Fig. 2, though the latter is only of five-ply structure. Fig. 5 shows six plies of veneer sheets 2 each of which has beveled ends whose beveled faces, unlike the counterparts of Fig. 4, face outwardly. Glued laminated wood resulting from such ~S layers of veneer sheets 2 after pressing is similar to the glued laminated wood of Fig. 3 after removal of the excess material from the ends as previously described. In Fig. 6, one end of each veneer sheet 2 is beveled while the other end thereof is square-cut, and each such veneer sheet is placed so that the ends 2_, 2b are substantially in verti-cal alignment with each other at their extreme ends.
Accordingly, after the veneer sheets 2 are deformed for laminating them into the glued laminated wood product, one face thereof will be formed flat while the other face will be formed with recessed po~tions -therein. In Fig. 7, each component veneer sheet 2 has ends 2a, 2_ which are chamfered or rounded, and which are spaced longitudinally apart on the opposite faces of the product, with reference to an , imaginary line (not shown~ extending perpendicular to its thickness. The resulting glued laminated wood will have recesses on both faces thereo-E, and the exposed edges of each veneer sheet 2 will be rounded, accordinyly.
S Further embodiments of the glued laminated wood of the invention will now be described with reference to E'igs.
8 - 25.
Fig. 8 shows a unit veneer sheet 3 having a longi-tudinal dimension Ll in the direction of its wood grain G.
A series of such unit veneer sheets 3 are laminated toge-ther in the above-described manner for ~uilding up glued laminated wood, from which laminated wood panel 4 of the embodiment shown in Fig. 9, having a five-~ply configuration, may be obtained~
In the embodiment of plywood 4 shown in Fig. 9, it is fabricated by parallel-laminating a series of the unit veneex sheets 3 of Fig. 8, with all of their grains G ex-tending in the longitudinal direction of the laminated wood to be made. ~herefore, each unit veneer sheet 3 will be offset in the direction of its wood grain from each adja-cent veneer at an interval of predetermined length Q l, so as to form a continuous length of parallel laminated wood. A panel 4 of any des~red length may be cut from such continuous length of glued parallel laminated wood.
The faces of the laminated wood ~ inevitably have recesses R formed therein adjacent to the ends of each veneer sheet 3, but these may be eliminated by applying any suitable filler material therein. If desired for any reason, such recesses may be retained as they are, without ~2~

any further additional processing, or additional grooviny may be provided so as to camouflage the recesses. Though the veneer sheet 3 in Fig. 8 is shown as a solid sheet, it may contain therein one or more joints 3a at which -two pieces of undersized veneer sheets are end-jointed to ma~e a full-si~ed unit veneer sheet having the length Ll, e.g. when it is desired to use veneers which are shorter than Ll. Such joints may be formed easily by using any known method such as butt-jointinyr scarf jointing, or an~ other convenient jointing.
Another embodiment of the glued parallel laminated wood 4 as shown in Fig. 10 is similar to that of Fig. 9, but differs therefrom in that the laminated wood is composed of veneer sheets 3 whose ends are beveled in the inwardly facing direction, thus corresponding to Fig. 2. This em-bodimen-t is advantageous as compared with its counterpart in Fig. 9, when continuity in surface flatness is a major concern in product quality~
Reference is now made to Fig. 11, wherein a unit veneer sheet 5, having the dimension L2 across its wood grain G is shown. A series of such unit veneer shee-ts 5 are used to fabricate a substantially continuous run of glued parallel laminated wood from which laminated wood 6 of any required length as shown in Fig. 12 may be cut.
~n the embodiment of ri~. 12, the parallel laminated wood 6 is made by laminating a series of the unit veneer sh~ets 5 of Fig. 11 in parallel relation to each other with all of their grains G extending across the longitu-nal direction of the product. Accordingly, each unit veneer sheet 5 will be offset, in the direction across the wood grain thereof, from each adjacent veneer sheet at a predetermined length in-terval Q2 for forming a con-tinuous length of glued parallel laminated wood. Thelaminated wood 6 of any desired length ma~ be obtained from such continuous length of parallel laminated wood.
Fig. 13 illustrates another embodiment of the glued parallel laminated wood 6, which is made using a series of laminated unit veneer sheets, 5 having beveled ends as in previous embodiments for preventing recesses from being produced on the product faces.
Referring to Fig. 14, a unit veneer sheet 7 is shown which, ~nlike the solid unit veneer sheets shown in Figs. 8 and 11, includes two pieces of undersized veneers 8 and ~ which are jointed together along their line of abutment 7a to make the full-sized unit veneer sheet 7 having a longitudinal dimension L3. The under-sized veneer 8 on the left-hand side as shown has it grain Gl oriented in the longitudinal direction of the laminated wood to be made; while the other undersized veneer 9 has its grain ~2 thereacross. When making a unit veneer sheet 7 which includes two jointed pieces of undersi~ed veneers 8 and 9, the dimension of the veneer 8 in the direction of its grain Gl and the dimension of the veneer 9 across its grain _2 should preferably be such that either of the di-mensions is greater than the interval lengths Q3 (Figs.
lS and 16) at which the unit veneer sheets 7 will be offset ~ , , ~' ~2~a~2 successively from each other in the lamination thereof for ma~ing of the laminated wood product~ ~y ~o doing, the abutment line 7_ may be prevented from appea.ring on the product faces. Furthermore, to maintain the s-trength of the res~llting laminated wood the climension of the ve-neer 8 having its grain Gl along the length L3 should preferably be the sum of said interval length Q3 and a dimension which is greater than five times, or more pre-ferabl~ in the range of from 15 to 150 times, the thickness of the veneer sheet 7 so that the jointing line 7a may not be positioned closely enough to the adjacent lapping end of its overlying veneer sheet to affect the strength of the laminated wood at such jointing line, as will be understood by those skilled iIl the art.
When a series of overlapped veneer sheets 7 having thçrein a side-to-end ~oint are glued together to form a laminated struc~ure according to the invention, glued la-minated wood 10 as shown in Fig. 15 will result. That is, in the illustrated case of a five~ply laminati~n, the upper two or three plies thereof have their grains Gl extending in the longitudinal direction of the glued la-minated wood 10, while the lower two or three plies have their grains G2 set thereacross.
The embodiment of plywood shown in Fig. 16 differs from that of Fig. 15 in that the glued laminated wood is made of similar unit veneer sheets 7, but each having its ends beveled in the inward direction, each unit veneer sheet being offset from another at a slightly smaller ~ a, interval, as previousl~ explained.
Fig. 17 shows still another Eorm oE a component unit veneer sheet 11 which is integrally formed by jointiny three sections of undersi~ed veneers 12, 13 and 1~/ along their respective lines of abutment lla, llb into a unit veneer sheet 11 having a longitudinal dimension L~. In this unit veneer sheet 11, its respective end sections 12 and 14 have their wood grains Gl extending in the direction oE the length L4, whereas the veneer section 13 at the center has it grain G2 extending thereacross. Each of the dimen-sions of the undersized veneers 12 and 14 in the direction of their grains G2 is made greater than the interval lengths Q~ (Figs. 18 and 19) at which the unit veneer sheets 11 will be offset from each other when laminated to make the glu~d laminated wood product. Furthermore, -the dimensions of said veneers 12 and 14 should preferably be the sum of said interval length Q4 and a dimension which is greater than five times, or more preferably in the ran~e of from S to 150 times, the thickness of the veneer sheet 11, Eor the same reasons stated previously in connection with Fig.
14.
Laminating a series of such integrally formed unit veneer sheets 11 o~ Fig. 17 into a five-ply structure ac-cording to the invention will eventually produce glued laminated wood 15 as illustrated in Fig. 18. In this em-bodiment, a cross-banded structure which is similar to a three-pl~ conEiguration can be created, as seen clearly at the side section thereof. That is, in the case of the 6~

ill~strated five-ply lamination, one or two plies o -the veneer she~ts 11 at the top and at the bottom of the ylued laminated wood 15 have their grains Gl extendiny in the direction of the length thereof, and two or three plies at the core portion of the laminated wood have their yrains G2 running thereacross.
-The embodiment of the glued laminated wood 15 in Fig. 19 differs from its counterpart shown in Fig. 18 in th~t each component unit veneer sheets 11 therefor has 10 beveled ends, and is offset from each of its adjacent ve-neer at a slightly smaller interval which corresponds with the beveling as previousl~ explained.
In Fig. 20, a unit veneer sheet 16 is shown which has th~ree sections of undersized veneers 17, 18 and 19 lS jointed together, along respective abutment lines 16a, 16b, into the length ~5 of a full-sized unit veneer sheet 16.
This veneer sheet 16 is similar to that shown in Fig. 17, but differs therefrom in that the undersigned veneer 18 at its center has its grain Gl extending in the direction 20 of the length L5, whereas the veneer sections 17 and 19 at the ends have their grains G2 extending thereacross.
Like the veneer sections 12 and 1~ ~Fig. 17), the under-sized veneers 17 and 19, as measured along the length L5 or across the grains G2 thereof, have dimensions greater than the length Q5 (FigS.21 and 22) of the intervals at 25 which the unit veneer sheets 16 will be offset from each other in the lamination thereof into a continuous length of glued laminated wood for the same reason stated in . .

connection with Fig~ 14.
The glued laminated wood 20 which results from la-minating such integrated unit veneer sheets 16 accordiny to the invention is shown in Fig. 21. ~ts cross-banded structure is arranged in a manner similar to that of the embodiment of FigO 18, althollgh each veneer la~er is re~
versed in respect of the direction of i~s wood grains.
Fig. 22 illustrates another embodiment of the glued laminated wood 20, wherein the ~aces thereof are formed 1~ flat, with no recesses such as those seen in Fig. 21, by providing inwardly beveled ends on each component unit veneer sheet 16, and laminating the veneer sheets with their ~e-veled ends o~erlapping and confron-ting one another, as previously explained.
Reference is now made to Fig. 23 which shows two unit veneer sheets 21 and 24, each having two sections of undersized veneers 22, 23 and 25, 26 respectively, which are jointed together at the lines of abutment 21a t 24a into unit veneer sheets having the length L6, respectively.
In the unit veneer sheet 21, its undersized veneer 22 has its grain Gl extending in the direction of the length L6, and the other veneer 23 has its grain G2 extending there-across. ~ith reference to the unit veneer sheet 24, its undersized veneer 25 has its grain G2 extending across the length L6 and the other veneer 26 has its grain Gl therealong~ The dimensions of the respec-tive undersized veneers 22~ 23, 25 and 26 as measured along the length L6 are preferabl~ made greater than the length ~6 (Figs.

$~2 24 and 25) o~ the intervals a-t which the unit veneer sheets 21 and 24 will be offset from one another in the lamination thereof when making a continuous le.nyth of glued laminated wood so that the abu-tment lines 21a and 24a may not appear on the faces of the resulting product.
As to the veneer sections 22 and 26 having their grains Gl extending along the length L6, the dimensions thereof along the length L6 should preferably be the sum of said interval length Q6 and a dimension which is greater than 10..' five times, or more preferabl~ in the range of from 15 to 150 times, the thickness o the veneer sheats 21, 24, to avoid a decrease in strength of the resulting product due to the abutment lines 21a and 24a being formed close to the adjacent lapping ends of the successive overlying unit ~ veneer sheets in the laminated wood structure. In the i.llus.tration of Fig. 23, the two unit veneer sheets 21 and 24 are made substantiall~ s~mmetrical with respest to the ~ointing lines 21a and 24a, respectively.
The glued laminated wood 27 which is made from the combination of the above two kinds of unit veneer sheets 21 and 24 is exemplified in Fig. 24~ In this parti.cular embodiment, the unit veneer shee~s are arranged and laid~
up in the ratio of two of the veneer sheets 21 to one of 2~ the veneer sheets 24, whereby glued laminated wood having a composite cross-banded structure is created, as seen at the side section thereof in Fig~ 24. Though not shown in the drawings, various embodiments of laminated wood having ~he ~nit veneer sheets arranged in ratios other than the , ~,, q~2 above two-to-one, e.g. one veneer sheet Zl to any desired number of veneer sheets 2~, three veneer sheets 21 to any desired number of veneer sheets 2~, and so ~orth, may be contemplated.
Fig. 25 exemplifies another embodiment which is si-milar to that of Fig. 24, but whose component uni-t veneers ha~e inwardly beveled ends, as shown.
As will now be apparent, the present invention can be utilized in making various types of glued laminated wood, l~ including laminated wood having parallel laminated veneers as well as cross~banded structure, depending upon the orien-tation of the wood grains of the component veneers and the selected combination of undersized veneers used in making the component unit veneer sheets. Since each t~pe of la-minated wood has its own applications, it will be apparant that each of the previously described embodiments has a particular use.
It would be preferable that the veneer sheets be used in the making of glued laminated wood according to the in~ention have a thickness in the range of from l to 4 mmO
Since the stepped deforma~ion of each veneer sheet which occurs during the process makes use of its inherent flexi-bility, the greater the thickness of the veneer sheets, the mcre difficult it will be to successfully make the product.
With this and the above range of preferred thicknesses of veneer sheets taken into consideration, the practical range of thicknesses of the resulting product will be from about 6 to 50 mm. Depending upon the veneer thickness and i~3 `
}~.r~ ~, ;8~

other factors, the present invention will exhibit a re markable advantaye in terms of economy when the component ~nit veneer sheets have dimensions of frorn 100 to 1,000 mm in the L direction. As to the number of plies in the la-S minated wood, any desired number can be selected, prefe-rable from within the range of from 3 to 12 plies according to various factors including the desired thickness of pro-duct to be made, the veneer thickness to be used, the particular wood species of which the venee~ is made, and lQ so on.

The method of manufacturing glued laminated wood, including plywood, according to the present invention will now be explained with reference to Figs. 26 to 31:

Fig. 26 shows a schematic diagram illustrating the basic procedural steps for manufacturing the continuously produced product, which include a gluing (adhesive applying~
process or station designated generally by reference letter A, followed se~uentially by a laying-up process or station B, a tacking station C, a cutting station D, and a final bonding station E.

In the gluing station A, a series of unit veneer sheets 2 each having the same length L and thickness are arranged with their respective leading ends lapped on the trailing ends of the preceding veneer sheets as shown in the drawing. In such arrangement, they are conveyed face-up by conveyor 28 in the direction of the arrow succesive-ly beneath a glue spreader 38, which coats the upper surfa-ces of the veneer sheets 2 with a continuous film of glue t .,Y ~.
. ~ `

~z~

which covers only the exposed surfaces thereof, the glue being indicated by the dots GL in the drawing. 'rhe coat-ing of glue may be accomplished by use of any suitable glue applying apparatus such as the glue spreader 38 shown schematically in Fig. 26, a curtain coater, a film-glue applying device which is disclosed in the Canadian Patent Application No. 418,699 filed on December 29, 1982 by Meinan Machinery Worlcs, or any other conventional means.
Anyway, the gluing process A is performed in such a way that no glue is applied to the opposite underside surface of each veneer sheet 2, or on the lapped upwardly facing portion at the trailing end of the veneer sheet. The length of overlap of each veneer sheet on the other is nominally equal to the quotient determined by dividing the unit veneer length L by the number N of plies to be in the laminated wood structure, i.e~ the same length as the length Q of offset of the veneer sheets in the laying up operation which follows.
~s thus coated with glue, the unit veneer sheets 2 are transferred to the subsequent laying-up station B, by sequentially dropping the sheets 2, as indicated by arrows F, from the con~eyor 28. On the laying-up conveyor 28a, each veneer sheet 2 is lapped only on the glued portion of its proceeding sheet, thereby exposing only the unglued 2~ portions of the veneer sheets. That is, in the laying-up station B each veneer sheet 2, which in the illustrated laying-up station has reversed its direction of movement from that of the ~luing conve~or 28, is laid on the preceding ~9 /~i ~;

~2~

veneer with its now unglued leading end exposed as a re-sult o~ the continuous or index;ny movement of the prece-ding veneer shee~. It will there~ore be apparent that the }apped length portion, or g~ue coated portion, on each veneer sheet is substantially equal to ~
As thus laid-up in a continuous, sequentially over-lapped length, the series o~ veneer sheets 2 are conveyed on conveyor 28a to the tacking station C, which includes a cold press (not shown) or any other convenient device, such as a stapler, a hot-melt glue applicator, etc., de-signed to temporarily hold the individual laid-up veneer sheets 2 together in a laminated form while malntaining the correct relative positions thereo~.
The continuous lamination of veneers thus formed is transferred to the subsequent cutting station D, where it is cut into the desired panel lengths. The panels are then moved to the bonding station E which includes a device, such as a hot press, designed to cure the layers of glue between the veneer sheets while pressing them to permanently set them in their desired deformed shapes having the tandemly arranged and displaced straight length portions lb and curved length protions lc (Fig. 1). As will be noted from Fig. 1, during the bonding operation at the station E, each straight length portion lb is displaced, in the direction o~ the thickness T of the product, by a distance substantially e~ual to the thickness t o~ its adjacent veneer sheet. Of course, if the product is made of veneers having verying thicknesses, the extents to which . ..~

~2~

its s-traight length portions are displaced will be corres-pondingly varied. E'or example, in a typical hot press operation, pressure on the order of about 7 to 21 kg/cm2 ~or about 3,000 to 9,000 lbs/ft2) is applie~ at a tempe-rature oE about 120 to 176C to cure the glue between the veneers and permanently set and bond them together.
In the described method of manufacturing glued la-minated wood, it is desirable during the gluing process A
that glue should be applied to each veneer sheet 2 leaving an appropriate unglued portion to allow very little of the glue to be exposed when it is laid-up on the preceding ve-neer sheet in the subsequent la~ing-up process B. For example, in an arrangement of veneer sheets 2 in the la~ving-up process B wherein each pair of adjacentl~ opposite ends 2a, 2_ of two overlapped veneer sheets 2 have their ends in vertical alignment with each other as exemplified by ~ull lines in the fragmenting side elevational showing of Fig. 27, each veneer sheet 2 will have an exposed portion of its surface on either face ~1hich is exactly e~ual to the distance of L/N twherein ~ represents the longitudinal di-mension of each unit veneer sheet 2; and N the number of veneer plies in ~he laminated wood to be made). As sta-ted earlier, in connection with the description of the product itself, the above-said distance, and therefore the surface area to be exposed, varies depending upon the shapes of the veneer ends, the sizes thereof, the relative positions of each pair of the adjacently opposite ends 2a~2b, etc.
For example, when the edges of each pair of corresponding j:" .:' 8~

veneer .sheet ends 2a and 2b are arranged or laid up in oth~r ways s~ch that one end overlaps the other a distance S, or such that the ends 2a, 2b are not in transverse alignment, but are spaced apart Erom each other in the longitudinal direction a distance S', as indicated by phantom lines in Fig. 27 respectivel~, the unglued area to be exposed should be decreased in the case of the over-lapping relation S, and increased when they are to be ~paced apart as shown by S', respectively. In either event, it i.s desirable that each v~neer sheet 2 have glue applied a~ station A in a way such as to maintain the appropriate ~nglued areas which will be exposed at the laying-up station B ~Fig. 26).
Although maintenance of such unglued portion on each veneer sheet 2 may be accomplished by properly contro'-ling the glue applying device 38, it is more convenient to apply glue in a continuous manner to the series of veneer sheets 2 which are successively lapped at -their ends using the appropriate lapping distance, thus permitting the use of any known type of glue applying device~ The length over w.h.ich. the respective ends of adjacent veneer sheets 2 are lapped on the gluing conve~or 28 ~Fig. 26) and as will pro-vide the unglued areas is determinea by the lengthwise dimension o~ the surface area to be exposed in ~he laying~
up process B (Fig. 26), which is the length interval Q
at which the veneers are laminated in offset relation to 2S each other. When the paired ends 2a, 2b of the upper and lower veneer sheets 2 in the laying-up process B are . . . ~

~2~
~ 34 -themselves to be longitudinally overlapped as indicaked by S, or are going to be longitudinally spaced apart from each other as at S' in Fig.~27, the lengths over which the ends of any two adjacen-t veneer sheets 2 are lapped in the gluing process A will be decreased or in-creased, accordingly, as indicated by phantom lines in Fig. 28. Regarding the value of S or S' r depending upon the usago of the glued laminated wood each is preferably within the range of less than 50 times or, more preferably, less than 5 times, the thickness of the unit veneer sheet 2 to be employed in making the product. Though it is ideal that the area of unglued surface obtained in the gluing process A and the area o~ sur~ace -to be exposed in the subse~uent laying-up process B should exactly coin-cide, errors are unavoidable in actual practice during both the gluing and the laying-up processes A and B. To compensate for such errors, any practical adjustment may be made, as by increasing or decreasing the areas of the unglued surfaces in the gluing station, etc.
Figs. 29 and 30 respectively illustrate two types of flight conveyors which may be used to transport the veneer sheets 2 while retaining the correct overlapping relation between them during either the gluing process A
or the laying-up process B (Fig. 26). The conveyor 28 shown in Fig. 29 includes several conveyor belts (onl~
one of which is shown in the drawing) having veneer sheet locating steps 29, for receiving the trailing ends of the veneer sheets~ The conve~or 30 in Fig. 30 includes several . .y ~, ~2~

conveyor belts ~only one of which is shown in -the drawing) having veneer sheet locating pins 31 projec-ting therefrom, for the same purpose. By placing each veneer sheet 2 onto the conveyors whether in automatic, se~ automatic or manual manner, it will be transported while being located and overlapped correctly in the longitudinal direction. Thus, a high standaxd of accuracy and stability in veneer posi-tioning can be achieved during the transporting of the veneer sheets through either the gluing or the laying-up processes.
~eferring now to Fig. 31, to permit the gluing and laying-up processes to be carried out in close conjunction with each other in order to synchronize the relative posi-tioning of the veneer sheets in the two processes, a com-mon drive 32 is provided for directly driving the conveyor 28 for the gliuing station A and for driving the conveyor 28a for the la~ing-up station B via any suitable speed-reducing davice 33, as shown schematically in Fig. 31. By such drive arrangement, the two different processes A and 2~ _ can be operatively synchronized so that error, if any, between the rates of travel of the veneer sheets during the two processes will take place at a given; and therefore, predictable value. Therefore, adjustment for compensating ths error may be made with ease.
2S If the drive 32 operates in a continuous manner, a cold press of a continuous type may be used in the tacking station C. If the drive 32 is capable of automatically interrupted operation, it is possible to employ a cold press having :~`f i ~2~
, intermittent operation for the tacking process C.
When it is permissible for the glue coating on the veneer sheets 2 to be e~posed in the subsecluent layiny-up process B, or when it is intended to have such exposure of glue on the product, the gluing process A may be con-ducted without maintaining the above-mentioned specific unglued areas on the veneer surfaces. For example, the veneer sheets 2 may be merely passed through the glue spreader 38 ~Fig. 26) one after another in end-to-end rela-tionship, without lapping their ends as shown in Fig. 28, so as to coat the glue on the entire surface of each veneer sheet. By so doing, a continuous length of glue exposure will appear on the face or faces of the continuously laid-up veneer sheets 2 formed in the laying-up station B.
Such exposure of glue on the laid-up veneers is permissible or even desired, depending upon -the type of laminated wood panel to be produced. For example, the glue which is ex-posed on the face can facilitate the application of an additional layer of overlay of a flat sheet o~ veneer, printed paper, hoard or any other suitable overlay material _ which would be laminated onto the face or faces of the product, as illustrated in ~ig~ 32. The overlay sheet O
may be added during or after the laying-up process, as desired.
Thus, it is to be understood that the particular embodiment o~ the method of manufacturing glued laminated wood according to the invention, specifically with refe-rence ~o the gluing process A, will vary depending upon ,. , .,~.
,,, ..i ., .~

its in-tended relationship with the subsequenk layiny-up process B. Thus, -the gluiny method may be conducted in a variety of ways other than those described above.
With reyards to the manner in which the gluiny and laying-up stations A and B are disposed relative to each other for transferring the veneer sheets from the former to the latter, they may be located on the same level by arranying the gluing station A on the upstream side and the laying-up station B on the downstream side with refe-rence to the direction of transfer of the veneer sheets 2, although th~y are located on different levels in the embodiment of Fig. 26. Furthermore, these two processes A and B may be arranged in line with each other, wherein the conveyor 28a is moved in the same direction as the conveyor 28, without being reversed as in the illustrated embodiment of Fig. 26, and instead each veneer sheet 2 coated with glue in the gluing station A is turned by reversing the leading and trailing ends thereof before it i5 transferred to the subsequent laying-up station B
to be lapped on the glued portion of its preceding sheet.

Therefore, th0se two stations may be opera-tively connected in any manner according to any specific r~quirements.
Furthermore~ in the method of laminated wood manu facturing shown in Fig. 26, the tacking process C may be either replaced by, or immediately followd by the bonding process E by substituting or adding a hot press of a type designed to operate in a continuous or intermittent manner, whereupon the laying-up process B and the final bonding ' i ~2~

process E can be integrated into a wholly continuous process. In such an arrangement, the continuously produced glued laminated wood can be cut into any desired leny-ths in the cutting process D which would then ~ollow the bonding process E. Thus, any desired lengths of plywood panels can be produced from a continuously produced run of glued laminated wood.
The present invention contemplates glued laminated wood having a novel laminated structure of veneers, which makes possible the formation of laminated wood of any desired length from veneer sheets wh-ich are too short or too narrow for such desired length of the product, thus permitting economical usage of veneer.
Regarding other general considerations associated with veneer or laminated wood making such as the kind of wood to be used, thickness, size, how to deal with lathe checks on the veneer surfaces, number of plies, adhesives to be used, moisture content in veneers, etc., none are affected in any way by the practice of the present invention, but ~o are subject to ordinary practices in glued laminated wood making.
~ hile the invention has been illustrated and described with reference to various specific embodiments, it is to be understood that various modifications in the details of the glued laminated wood construction or its method of manufac-ture may be made withou-t departing from the spirit and scope of the invention.

, . ~

Claims (23)

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. Glued laminated wood comprising a laminated plu-rality of lapped veneer sheets, at least one of said veneer sheets having at least two straight length portions which are disposed in tandem relation and parallel to each other, each of said straight length portions of said one veneer sheet being successively displaced from each other in the direction of the thickness of said glued laminated wood, said one veneer sheet further having a curved length portion extending between each two successive straight length por-tions, and a lapping veneer sheet on each side of said one veneer sheet, each said lapping veneer sheet comprising a straight length portion which is laminated to one of said two straight length portions of said one veneer sheet, the distance of said displacement of said two straight length portions of said one veneer sheet from each other being substantially equal to the thickness of said straight length portion of at least one of said lapping veneer sheets.

2. Glued laminated wood having N layers of veneer sheets and cut from a substantially continuously producible length of glued laminated wood formed by laying up and la-minating successively lapped unit veneer sheets, each unit veneer sheet having a length L as measured in the direction of said laying-up and a thickness t, and said unit veneer sheets being successively offset from each other in the di-rection of said laying-up at a length interval ? with respect to its underlying unit veneer sheet, each of said unit veneer sheets as it appears in said continuously producible length of glued laminated wood having N-number of straight length portions which are disposed in tandem relation and succes-sively displaced from each other in the direction of the thickness of said continuously producible length of glued laminated wood a distance substantially equal to said thick-ness t, and each said unit veneer sheet as it appears in said continuously producible length of glued laminated wood further having a curved length portions between each pair of its said straight length portions, all of said unit veneer sheet straight length portions being parallel to each other, and each of said unit veneer sheets extending through said thick-ness of said continuously producible length of glued lamina-ted wood from one surface thereof of the other with the endmost of its said straight length portions forming respect-ive portions of the opposite faces of said continuously producible length of glued laminated wood.

3. Glued laminated wood according to claim 2, wherein said length interval ? is substantially equal to L
divided by N.

4. Glued laminated wood according to claim 2, wherein said length interval ? is within the range of from L divided by N plus 50 times said thickness t of each said unit veneer sheet, to L divided by N minus 50 times said thickness t of each said unit veneer sheet.

5. Glued laminated wood according to claim 4, wherein said length interval ? is within the range of from L divided by N plus 5 times said thickness t of each said unit veneer sheet, to L divided by N minus 5 times said thickness ? of each said unit veneer sheet.

6. Glued laminated wood according to claim 2, wherein each said unit veneer sheet comprises a solid sheet of veneer having said length L.

7. Glued laminated wood according to claim 2, wherein each said unit veneer sheet comprises at least two undersized sheets of veneer which are jointed together to form said unit veneer sheet.

8. Glued laminated wood according to claim 7, wherein each said undersized sheet of veneer which is disposed at an end of said unit veneer sheet has a length, as measured in the direction L, which is greater than said length ?.

9. Glued laminated wood according to claim 7, wherein each said undersized sheet of veneer which is disposed at an end of said unit veneer sheet has a length, as measured in the direction of L, which is susbtantially equal to the sum of said length interval ? and a dimension which is from about 5 to about 150 times said thickness t of said unit veneer sheet.

10. Glued laminated wood according to claim 7, wherein said undersized sheets of veneer are jointed to-gether in end-to-end relation with reference to the di-rections of their respective wood grains.

11. Glued laminated wood according to claim 7, wherein said undersized sheets of veneer are jointed to-gether in end-to-side relation with reference to the directions of their respective wood grains.

12. Glued laminated wood according to claim 2, wherein each said unit veneer sheet has opposite ends at least one of which is beveled, whereby at least one face of said glued laminated wood is substantially smooth.

13. Glued laminated wood according to claim 1, which further comprises overlay material laminated onto at least one of the faces of said glued laminated wood.

14. Method of manufacturing glued laminated wood comprising providing a plurality of unit veneer sheets, applying glue to said unit veneer sheet, laying up said unit veneer sheets in successively lapped relation in one direction of overlap, each of said unit veneer sheets having substantially the same length in the direction of said laying-up, the successive length intervals of overlap of each said unit veneer sheet on another in said direction of overlap each being nominally equal to said unit veneer sheet length minus the quotient determined by dividing said unit veneer sheet length by the number of plies to be in said glued laminated wood, and pressing and curing said-laid-up veneer sheets to permanently deform and bond the same and thereby establish the thickness of said glued la-minated wood, each of said deformed unit veneer sheets having a plurality of straight length portions and respective curved length portions between any two adjacent ones of its said straight length portions, said straight length portions being in tandem parallel relation to each other and successively displaced from each other in the direction of the thickness of said glued laminated wood by a distance substantially equal to the thickness of the immediately adjacent, lapped veneer sheet.

15. Method according to claim 14, wherein each of said unit veneer sheets has equal thickness, and said length interval of overlap of each said unit veneer sheet on another is varied from said nominal length interval by a length which is up to 50 times the thickness of one of said unit veneer sheets.

16. Method according to claim 14, wherein said step of applying glue to said unit veneer sheets comprises arranging said unit veneer sheets in successively lapped relation in the direction of their said lengths, the length interval of overlap of each said unit veneer sheet on another in said arranging being nominally equal to said unit veneer sheet length divided by the number of plies to be in said glued laminated wood, coating said glue substantially continuously along those overlapped surfaces of said unit veneer sheets which face on one direction whereby said length interval on each unit veneer sheet is shielded from said coating of glue, and said subsequent step of laying up said unit veneer sheets comprises subs-tantially reversing the length interval of overlap of said unit veneer sheets whereby said glue coating glues the respective of said sheets one to another in successively overlapped relation with said shielded length intervals on said sheets being exposed.

17. Method according to claim 16, wherein during said arranging of said unit veneer sheets, said overlapped unit veneer sheets are conveyed in said arrangement by a first conveying means with said glue-coated surfaces thereof facing upwardly and said substantially reversing the length interval of overlap of said unit veneer sheets comprises feeding said unit veneer sheets one at a time off from said arrangement of said unit veneer sheets and laying up said unit veneer sheets while conveying the same by a second conveying means.

18. Method according to claim 17, wherein said step of substantially reversing the length interval of overlap comprises feeding said unit veneer sheets one at a time off from the underside of said arrangement of unit veneer sheets and dropping said unit veneer sheets on to said second conveying means, said second conveying means being disposed below said first conveying means, and con-veying said sheets in direction which is substantially opposite to that of said first conveying means.

19. Method according to claim 15, wherein said length interval of overlap of each said unit veneer sheet on another is varied from said nominal length interval by a length which is up to 5 times the thickness of one of said unit veneer sheets.

20. Method according to claim 14, wherein each said unit veneer sheet comprises a solid sheet of veneer.

21. Method according to claim 14, wherein each said unit veneer sheet comprises at least two undersized sheets of veneer which are integrally jointed together to form said length of each said unit veneer sheet.

22. Method according to claim 21, wherein each said undersized sheet of veneer which is disposed at and forms an end of said unit veneer sheet has a length, as measured in the direction of said laying-up, which is greater than a dimension determined by dividing said unit veneer sheet length by the number of plies to be in said glued laminated wood.

23. Method according to claim 21, wherein each said undersized veneer sheet which is disposed at and forms an end of said unit veneer sheet has a length, as measured in the direction of said laying-up, which is greater than said dimension by an amount which is from about 5 to about 150 times the thickness of said unit veneer sheet.