US1870041A - Method and apparatus for the formation of plywood and the like - Google Patents

Description

T. W- DIKE Filed May 21, 1951 5 Sheets-Sheet l m hr IN VEN TOR. Tmmwm a BY -v ATTORNEYS Aug. 2, 1932.

METHOD AND APPARATUS FOR THE FORMATION OF PLYWOOD AND THE LIKE will! T. W. DIKE Aug. 2, I932.

METHOD AND APPARATUS FOR THE FORMATION OF PLYWOOD AND THE LIKE Filed lay'zl, 1951 5 Sheets-Sheet 2 IN VEN TOR.

A TTORNEYS.

T- W. DIKE Aug. 2, 1932.

METHOD AND APPARATUS THE FORMATION OF PLYWOOD AND THE LIKE 5 Sheets-Sheet 5 Filed Hay 21, 1931 1 INVENTOR.

A TTORNEYS.

Aug. 2, 1932. 'r w. DIKE'. I 1,870,041

METHOD AND APPARATUS FOR THE FORMATION OF PLYWOOD AND THE LIKE HESS/fly I N VEN TOR. T G'AoW M- B Y ixb A TTORNEYS.

METHOD AND APPARATUS FOR THE FORMATION OF PLYWOOD AND mp LIKE T. W. DIKE Aug. 2, 1932.

Filed May 21, 1951 5 Sheets-Sheet 5 Q mQQ 36u G SEJ SMFAMWMLM- Dam BY A TTURNEYS. V

and apparatus, an

Patented Aug. 2, 1932 lum'rao STATES."

PATENT OFFICE THEODORE WILLIAMS DIKE, OF NEW WESTMINSTER, BRITISH COLUMBIA, CANADA, ASSIGNOB TO ,I. F. LA' U'CKS, INC.,-OF SEATTLE. WASHINGTQN, A. CORPQRATION OF wasnmerou mn'raon AND arrnnarus roa THE romrxon or rrr woon AND THE m Application Med May 21,

v This invention relates to gluing methods to provide improved methods whereby mem bers may be readily, efficiently and effectively united in a desirable manner. Another object is toprovide methods whereby there may be readily produced high grade structures of uniform quality.

A further object is to provide improved methods whereby'there may be efi'ectively and efiiciently produced plywood which possess strength; endurance and appearance and other qualities of a nature which are particularly desirable for themes to which the plywood produced is to be put.

Another object is the provision of 'a method of forming plywood, wherein each finished panel of a series will have qualities as closely as'possible like those of each other P el of said series.

More specifically, it is an object of the invention to continuously produce a series of panels of substant ally uniform qualities I and characteristics.

Another object is' to combine a plurality of plies into a panel with particular efiiciency and effectiveness.

Another object is to provide apparatus adapted for use in certain procedures involved in carrying out methods such as contemplated by the invention.

A further object is to provide certain forms of apparatus adapted for the efiicientand cf fective production of plywood.

Other objects of the invention will in part bfet obvious and will in part appear hereina er. 1

more. particularly tov methods and apparatus for the formation 1931. seriatuo. 538,883. I

The invention accordingly comprises the several steps and the relation and order of be had to the following detailed description taken in connection with the accompanying dravn'ngs, in which:

Fig. 1 is a somewhat diagrammatic plan view of apparatus exemplifying one form of method embodying the invention;

Fig. '2 is a partly-sectional side View on an enlarged scale exemplifying one type of means for applying gluing materials to materials to be glued in carrying out the invention Fig. 3 is a side view exemplifying one type .of bonding mechanism adapted for use .in

carrying out the invention;

Fig. 4is a somewhat diagrammatic plan view of another type of bonding mechanism adapted for use in carrying out the invention- I Fig. 5 is a side view of another form of apparatus adapted for use in carrying out the invention;

Fig. 6 is a plan view of still another form; Fig. 7 is a side view of a further modified form of apparatus; 7

Fig. 8 is a somewhat diagrammatic plan. view of apparatus exemplifying an additional procedure adapted to be performed in accordance with the invention; 7

Fig. 9 is a side view exemplifying one type of apparatus for disposing plies on a. conveyor in accordance with the invention;

' Fig. '10 is asimilar view of another form;

. Fig. 11 is a side view of apparatus exemplifying another form of the invention;

. Fig. 12 is an enlarged side view of an arrangement ready for pressing, asindicated in Fig. 11; and

Fig. 13 is a somewhat diagrammatic showing of another type of means for applying powdered adhesive material to members to be glued.

While the invention in many of its aspects is adapted foruse in a wide variety of gluing methods, it is more particularly concerned with the formation of plywood, and, in many of its aspects deals with the solution of problems met with primarily in the gluing of veneers, or other materials of a relatively porous or fibrous nature.

Itis to be understood in this connection that the term plywood as used herein, is intended to include not only laminated structures, the plies of which are composed of natural wood, but also structures, of which part, and in some cases all, of the plies are composed of artificial sheet material used as substitutes for natural wood plies, and that it does not exclude structures wherein there are also included one or more plies of other material such for instance as steel, aluminum, paper, etc.

A broad variety of gluing methods adapted for use in the formation of plywood have been proposed. While many of these methods have a relatively wide use there is still a large and unsatisfied demand for plywood panels having a relatively large number of desirable qualities. Among such qualities are uniformity of strength, durability and appearance, both among the panels of a group and throughout an individual panel; freedom from blisters, cracks or strained portions; and, in many cases, water-resistance; and resistance to temperature conditions. There is also a wide field for use of plywood in place of other, and often inferior, materials, which field can be occupied by plywood produced in quantities at a relatively small cost and with substantial freedom from objectionabledeof the foregoing desirable qualities, and it is particularly desirable that such plywood be produced in quantity with a maximum of uniformity and efliciency, and a minimum of labor or expense.

With the foregoing and other ends 'in' view the present invention contemplates the provision of improved methods adapted for the expeditious and effective production of plywood, and particularly for-so producing ply- Wood in a manner well adapted for the man ufacture of quality products.

The gluing methods in common use give rise to numerous difficulties in effectiveness of operation and in quality of product, due in part to the use of liquid glues and in part to the haphazard methods employed, and with proved methods ,and apparatus involving such applications that outstanding results may be obtained.

In connection with the exemplification of such methods, reference will be made to various forms of apparatus which may be used in the performance thereof. A number of such forms" of apparatus, which are illustrated and described herein to the end that a more ready understanding of the present invention may be had, form the subject matter of various applications of myself and others which have been previously filed, are filed herewith, or will be filed in the future. The present invention, however, contemplates also the provision of certain forms of apparatus particularly adapted for use in the performance of such methods. To a like end, reference will also be made to various methods which form the subject matter of applications of myself and others, and not claimed herein.

It is particularly to be understood that while various preferred types. of methods and apparatus are exemplified herein, the invention nevertheless embraces a wide variety of procedures and apparatus and that the various steps and mechanisms exemplified may be widely modified. Moreover, steps or mechanism exemplified in connection with the description of preferred forms of procedure or apparatus may in many instances be omitted without departing from the invention in its broader aspects.

In its preferred fornf, he invention contemplates continuously and concurrently applying gluing material, (i( e. any material utilized in the joining of the plies) to surfaces of plies of one or more series, and building up assemblies including the coated surfaces in a manner such that a series of assemblies will be completed one'after another by steps which are substantially uniform for each assembly, and, preferably, at intervals spaced but ashort time one from the other; delivering each assembly to bonding mechanism in a uniform, and preferably short, time interval after it is completed; and subjecting each assembly to bonding conditions for a uniform, and preferably for a relatively short, time interval. I In general, each of the steps or procedures above noted may be accomplished in a variety of ways, several of which will be mentioned immediately below, and a few of which will be particularly exemplified hereinafter, it beingborne in mind that certain of the procedures outlined and exemplifiedare particu' larly adapted for use under certain conditions andin certain particular types of operations, while others thereof are particularly adapted for use under other conditions and in other particular types of operations.

' The coating of plies may be readily accomplished, for example, by moving a series of plies one after another along a path such that of each of-two other series associated with the coatedsurface in any suitable manner or any suitable time for each ply of the first series- Other suitable variations in the surfaces coated and the manner of associating plys of difl'erent series may be made. It is of importance, however, in obtaining panels of particularly uniform qualities that the coating and assembling steps with respect to the plys of the various series should be similar throughout. 1

The gluing material applied ordinarily consists of or includes material which in itself possesses adhesive qualities or which, under the conditions obtaining at the glue line, is converted into a substance possessing such qualities. All such materials will-be referred to herein as adhesive materials. Such materials may be such as require a given amount of plasticizing agent for effecting the desired union at the glue line, or may be materials which under suitable conditions, such as the presence of heat are suitably plasticized.

n the case of materials requiring the presence of a plasticizing medium an additional gluingmaterial in the nature of aplasticizing medium, for. example, water, may be supplied thereto. Iir instances where one or more of the plies themselves contain sufficient excess moisture so that they will yield up such moisture to the adhesive material, no .ad-' titional supply of plasticizing medium is ordinarily necessary. However, in the gluing of relatively dry materials, which inmany cases is a preferable procedure, it is in some cases desirable to apply a liquid. forexample, water, in suitable proportions either before, with, or after the application of an adhesive material, or at two or more such times. j 1

Other suitable addition agents may be -applied with one-or another of the materials applied, or separately therefrom, as desired.

The application of adhesive or other materials to the surfaces of the plies, i. e., the spreading or .coating ofthe pliesfmav be accomplished in a variety of ways. Mention lay be made of various examples of spread- 1g procedures. The plies may besucces- .ively passed through a zone in which an adhesive or other material isdisseminated in such manner that it will be received by a surface of. each ply as the ply passes through said zone; for example, as described and claimed in my co-pending application, Serial #518,944, filed February 28, 1931. The plies may be otherwise coated in a suitable manner without contact of the applying means with'the coated surface. The plies may be successively dipped in, passed thru, or otherwise brought into contact with the adhesive material. One surface only of eachply may be coated in a single operation or both surfaces of a ply may beso coated. It will be appreciated that various types of such pro-' cedures are particularly advantageous in ormed-between the coating ofvarious of the surfaces contained in the assembly being formed or after all the coating steps, as best suitsthe type of operation and the characteristics desirable in the particular operation involved.

The bonding of the assemblies and the delivery of the same to bonding mechanism 1s preferably accomplished with the greatest possible uniformity consistent with the type of operation. In its broader aspects the 1nvention contemplates performing a bonding operation either with or without the use of. heat. For example, there may be utllized either a hot or a cold press or a combination of-the two, and in certain instances there may be utilized heat which has been stored in one or more of the plies.- In the latter connec-. tion'reference is made to the co-pending application of Irving 17. Laucks, Charles N. Gone, and myself, Serial No. 447,428, filed April 25, 1930, issued March 29, 1932, as Patcnt No. 1,851,709. VProcesses involving the utilization of heat are especially desirable for use in many cases because ofsthe manner in which bonding is often'jexpedit'ed thereby,

,and because of its action in securing'eifective bonding in many desirable types of procedures". w r 1 Preferably eachassemblyis pressed individually, such action being obtained either in a continuous press wherein the assemblies are progressed between the. pressure plates during the pressing operation, or-by the use of a plurality of independently-operable pressure mechanisms to which the assemblies are successively delivered. When a continuous press is used the same may be disposed in the path-of movement of the plies so that each assembly as it is formed is moved di rectly between ithe plates of the pressing mechanism and progressed 'therebetween.

' When independently-operatedpressuremechanisms are used the delivery thereto is preferably so timed that the time of delivery of each assembly to a pressing mechanism 1 is the same as the time of delivery of every other assembly. However, in some cases a slight sacrifice in uniformity may be made and a multiple opening press utilized provided suitabletcare is exercised in promptly loading the press. Such a procedure finds its most likely applications in cases Where the adhesive materials used are not subject to rapid change and where the materials glued do not tend to change the conditions at the glue line by the absorption of water from or addition of water to the adhesive material short time.

or otherwise.

Whatever type of bonding mechanism is used, the delivery of the assemblies thereto is preferably accomplished in a relatively In instances where a continuous press is employed, this time may be reduced almost to a vanishing point. I

In many of its broader aspects the inven-- tion contemplates carrying out the procedures in question in either short or long time I intervals, as may be advisable in the particular operation being carried out. In a number of instances, however,'the efiiciency and eflectiveness of methods such as contemplated by the invention may be enhancedby so conducting certain of the steps that the performance thereof does not occupy more than a given period of time. In this manner the other conditions under which the operation' is conducted be so arranged that the bonding operation itself will not'exceed the equivalent of 1 minute based on the use of face and back plies thick.

In bonding operations utilizing heat as well as pressure, it is'desirable to avoid any changes in the character of the glue prior to the, time when the pressure conditions are proper for bond formation; In particular, when heat co'agulable glues are used themagulation of such glues before the surfaces to be bonded areunder full pressure results in the formation of' unsatisfactory bonds. Again, in the use of glues embodying a small amount of moisture premature and uneven drying is especially undesirable. Various It is. furthermore prefother premature heateflects also have objectionable results. With a view to avoiding these and other difficulties pressure may, in certain instances, be applied at a time not substantially later than the time when heat reaches the glue line, but without substantial loss of time in the heating of the assembly after the pressure has been fully applied.

In instances where the adhesivematerial is maintained in or converted into a more or less fluid condition by the presence of a plasticizing liquid, such as Water, as distinguished from instances where only heat or other agency is utilized for this purpose, it ispreferable that the water or other -plasticizing liquid be present in a definitely controlled amount, although; as above set forth, the

of moisture may be limited by partly drying the same. In instances involving the use of adhesives utilizing water in the uniting of dry material or materials, such as commercially dry veneers, for instance veneers which have recently been dried by a veneer drier or redried in a veneer redryer, which will not give up any substantial amount of moisture to the adhesive material, the moisture supplied may be readily controlled. In instances wherein the moisture is applied from an out side source to materials of a relatively porous nature, the possibility of absorption losses must be taken into account. Evaporation losses, even in relatively rapid processes, may also occur to some slight extent. It has been found thatthe proportion of water to be applied to commercially dry veneer for the plasticization of water plasticizable adhesive material on each thousand square feet of sin- 'gle glue line area should preferably range between 5 lbs. and 30 lbs. and that the'best results are usually obtained when it does not exceed 25 lbs. and often when it does not exceed 20 lbs. If a plasticizing agent other than water is to be utilized, such figuresas are given should be modified in accordance with the known plasticizing power of the agent utilized.

By following out a procedure such as out lined immediately above, a final product haviing a desired final or shipping moisture content can be readily obtained in a simple and expeditious manner.

There are outlined below examples of procedures carried out in accordance with the above:

Erm mplei 3 plies of 1/24" commercla d veneer of light weight wodd 5 I reducing a- -pane1 weighing 600 lbs. per 1,000 sq. ft. bone b 15'1bs. of water content Moisture content of product Total lbs.

, Example 2 3 plies of commercially dry veneerof heav wood producing a panel we ghing 1200 lbs. per 1000 sq. ft. bone dry Moisture content of veneer 6% Soya bean flour spread at 32 lbs.

per 1000 sq. ft. of three-ply panel (two glue lines) Plasticlzinfg liquid containing 24 lbs. 0 water per 1000 sq. ft. of single glue line a: 2

Moisture content of product 10% from 120 lbs.

It is to be noted that in both these examples representing a wide range of conditions the moisture supplied is below 50 lbs. per thousand square feet of three-ply product and below 25 lbs. per thousand square feet of single glue line area; and that in neither case can the finished panel have a moisture content greater than 10% when it comesfrom the press. This figure is well within the range of desirable shipping moisture contents.

It is also to be noted that in a number of, instances wherein moisture is supplied, it is desirable that the amount of moisture supplied be limited to that required for elfecting the desired union at the glue line.

r It is to be borne in mind that while many of the forms of procedure hereinafter exem lified are conducted most efi'ectively and satisfactorilyunder conditions which do not involve the use of plasticizing liquid in amounts materially greater than set forth in the above discussion, the invention in many of its aspects is not limited to such uses. While many of the forms of methods suggested or exemplified herein have anumber of advantageous features, whether or notthe pressing is carried on in the presence of heat, inmost cases the use of heat is preferable because-ofits action in efiectingzo'r accelerating the-setting of a large number of adhesive materials. Both the'intensity and the duration of the heat application may be varied to a considerable extent in accordance with the conditions existing'within the'assembly dur- 1 ing the formation of the bond. A few adhesives, such as the albumens, may be set at tem pertures somewhat below 212, but the action 65 is slow and it'is often desirable to heat the 72 lbs. of water content per thousand 5 lbs. of water conof vaporizable material, for example, moispressure plates to temperatures between 212 F. and 300 F. It is to be borne in mind in th1s connection that the heat should preferably be so controlled as to prevent the development of bursting pressures within the assembly, while at the same time utilizing sufficient heat to set the adhesive. The degree of heat must be correlated somewhat with the. time of pressing, since it has been found that there is often an interval between the maximum time necessary for setting and the minimum time necessary to avoid blistering at a given heat. For example, in bonding an assembly of three plies of birch lued with blood albumen in the presence of 10% lime between pressure plates, heated to 240 F.,

. neither satisfactory bonding nor noticeable blistering'occurred in fifteen seconds, whereas in ninety seconds there was a blister force sufiicient to cause rupture, although there was a strong bond. At thirty seconds there was a weak bond and no substantial blistering. However, pressure for between forty-five and seventy-five seconds resulted in the formation of a strong bond, without substantial tendency to'blister. In its preferred form, moreover, the invention contemplates conducting the bonding operation under conditions wherein the quantity ture, in the pressed panel is not reduceda substantial amount below the quantity of vaporizable materal in the original plies.

After the binding is completed, the panel may, if desired, be subjected to a finishing op; eration. It is often desirable that such a step be initiated within relatively short time after the completion of the bonding-operation, and

in such cases a time not greater thanfive mine e utes is preferred. This time allows ample op- 10 portumty for the panel to cool, if it has been bonded under heat, while nevertheless exce sive delay is avoided:

One method of embodying the nvention arid adapted for the formation of 1 'a three-ply panel is particularly exemplified in -Figure 1. A series of plies or .squares? 20 are. taken one, at a time from a stack 21 and laid upon the active run of a conveyor 22 by which they aremoved suc- 1 cessively-forward. Gluing material is thereupon applied to the upper surface of each of.

the movingplies as indicated at 23. Any of a number of suitable forms of methods and mechanisms may be employed to perform thisv 1 glue applying or spreading step, besides those particularly exemplified hereinafter (as for example in Fig 2).

After the spreading of each ply is 'completed one of a series of plies 26L is-taken from .125

a stack 25and laid on the coated ply 20, after which gluing material is applied, as indicated at 26, to the upper surface of each ply 24 as the movement continues. One of a' series of plies 27 'is thereupon taken from a stack 28 no and laid upon the partial assembly comprising the lies 20 and 24. After each assembly is comp eted the same is delivered to suitable bonding mechanism and subjected to bonding conditions, as for example by a pressing step as indicated at 29.

One method and means for performing the spreading is exemplified in Figure 2. In

this connection, reference is made to my copending applications Serial No. 518,944 filed February 28, 1931, and Serial No. 596,070, filed March 1, 1932, and the copending application of Walter D. Lawshe, myself, and Charles N. Cone, Serial No. 518,945, filed February 28, 1931, as well as other inventive concepts. In this arrangement each ply or partial assembly, for example 3, ply 20, as it 9 moves on the conveyor 22 passes first through a zone in which an aqueous mist 33 is ejected by an atomizer 34, then through a zone in which a cloud of powdered adhesive material is disseminated by a rotary brush 35, to which the adhesive material is delivered by a roll 36. p The periphery of the roll 36 is provided with indentations in the forms of grooves 37, and extends into the bottom of a hopper 38 containing a supply of powdered adhesive material 39. Thereafter the ply passes through a zone in which an aqueous mist 41 is disseminated by atomizer J 42. By the operation of a. valve 43, or in any other suitable manner, the supply of moisture may be so controlled as to limit he moisture at the glue line to substantially t at required for the plasticization of the adhesive material in any particular case. This form of spreading mechanism is accordingly well 576,766, filed November 23, 1931. One type Merritt, Serial No. 599,942 filed March 19,

1932, is particularly exem lified in the form of apparatusembodied in igure 4. In this arrangement each assembly which is completed on conveyormeans such as the conveyor22, moves onto a conveyor which is operated at a considerably higher speed than the conveyor 22 so as to space the assemblies one from. another, as contemplated by the. present invention. As the assembly "reaches the end of the active run of the conveyor 60 it passes onto one end or the other of a shuttle conveyor 61. This shuttle conveyor is arranged to move back andrforth at timed intervals such that as an assembly is delivered to one end thereof a previously received assemblymay be removed from the other end and disposed in one of aplurality of suitable presses 62, and pressure applied. Prefer ably each movement from the shuttle conveyor 61 to the press .62 is performed immediatel after the shuttle conveyor places the assein l and occupies a time interval of constant len h. It will accordingly be seen that the time between the com letion of each,

assembly and the delivery of t e same to one or another of-the presses is thesame as the time of delivery of each other assembly. The

ressure time of each assembly'is likewise preferably kept constant. After pressing, each panel may be placed on a transfer sup- .port 63 and thence moved onto one or the other of a pair of ofibearing conveyors 64, by

1 adapted for use the Production of high which it is carried away to a finishmg mechaquality anels in a particularly short time.

One orm of pressing mechanism which may be utilized in accordance with the invention is exemplified in Figure 3. This comprises a pair of endless-belt or caterpillar members 52 and 53, the active runs of which are adapted to be pressed toward one another by suitable means, such as the diagrammatically illustrated compression members 54 and 55. Assemblies including the ,plies 20, 24 and 27 may substantially immediately after their completion be run ofi the end of the.

- conveyor 22 and between the caterpillar ele- I throng nism or a store e room. When the conveyors 64 are ut' ized to carry panels from hot presses t0 finishing mechanisms the ac-' the runs. thereof are preferably sufliciently extended so that the panels will have cooled to a desired extnt by finishing mechanism.

It is to be notedthat in the utilization of bonding mechanism such as exemplified in both Figs. 3 and 4, in cases where heated press elements are emuloyed, the two sides of each of the assemblies treated aresubjected to uniform heat. and pressure conditions.

An especially simple form of method ndthe time they reach the "apparatus embodying certain features 0 the invention is exemplified in Fig. 5. Plies 65 are taken from a stack 66 and laid at spaced intervals on the upper run of a conveyor 67. Each Ely 65 is moved by the conveyor a zone in which 'a ueous particles 68 aredisseminated by suita le means such as an-atomiz'er 69 and then through a zone in which powdered adhesive material 70 is disseminate'd by suitable means such as :1. vi- 7 brating screen. 71. One of a series of plies '72 taken from a stack 73 is thereupon laid cation of Ericsson H. Merritt, Serial No. 'uponthe ply 65 and the assembly thus formed is runonto a support 74 and preferably immediately, placed in a press 7 5. Under conditions that permit quick pressing-for ex-- erly spaced on the conveyor 67, a pressing of 9 one panel will be completed as another panel reaches the support 74 ready for pressing. As the bonding of each panel is completed, it is moved from the press '7 to a suitable support 76.

a While the path traversed by the plies dur- 7 thereupon lifted, turned over and placed with ing the performance of the spreading and assembly operations is preferably a straight line, such a path, when so traversed, maybe other than a straight line in many instances.

One such arrangement is exemplified in Fig. 6, wherein there is illustrated an apparatus comprising a pair of parallel con'-' veyors 77 .and 78. The plies 7 9 of a series are placed successively on a conveyor 7 7 and 954 passed through a zone 80 in'which a disseminated liquid is falling, through a zone 81 in which a disseminated powder is falling, and through a zone 82 in which a disseminatedliquid is falling. Each coated ply is its coated surface downward upon the upper surface of one of a series of plies 83, which are placed one at atime on the conveyor 7 8. Each partial assembly thus formed is passed through zones 84, 85 and 86 similar to the zones 80, 81 and 82, and an additional ply 87 disposed against the coated surface of this partial assembly. Each assembly thus.

formed is thereupon delivered to pressing mechanism,-for example, in one or another of the manners indicated above,an'd.pressed -therein.

In Fig. 7 there is shown. insomewhat greater detail one form of apparatus such as be utilized in performing an operation suc as indicated in Fig. 1. Automatic means 98 a're provided for moving eahh ply 20 from a stack 21. Elevator means indicated diagrammatically at 99, are provided for lifting the stack 21 as plies 20 are removed therefrom.

Forms of apparatus of this nature form the subject matter of an application by Ericsson H.

Merritt, Serial No. 594,011;filed February 19,

'55 1932. Such apparatus, as well as other types 4 of apparatus to this end will be more particul a'rly exemplified hereinafter. Similar apparatus is exemplified at 100 and 101 in connection with the stack 25; and at 102 and 50103 in connection with the stack 28. Disseminating means comprising elements 104,

105 and '106 are exemplified as disposed between thestacks 21. and 25 and between the stacks 25 and 28. .After each completed as sembly is formed it is passed between the caterpillar elements 52 and 53 of a continuous press.

The pressed panels, whether pressed in a continuous or an intermittent pressing mechanism, and whether pressed individually or together, maybe withdrawn from a press and permitted to cool and thereupon subjected to such finishing operations as may be desirable. When the water or other plas ticizing agent, with the exception of such small part thereof as may have evaporated during the pressing, has been utilized in the bond formation substantially in its entirety,

' there is no necessity for subjecting the panels to further dryin operations. They can ac-' cordingly be con noted in a suitable manner as, for example; on a conveyor 121, Fig. 8, to a sanding mechanism 122 or other smoothing'apparatus, and thence immediately to a trimmer or other device for properly completing the finishing. The run of the con- .Veyor 121 between the press' and the sander should, preferably, be of suflicientlength to allow for the proper cooling of the panels durin their movement. In, igure 9 there is exemplified one type of automatic means adapted for use in moving a ply from a osition at'one side of a conveyor and setting it on a conveyor or on a coated surface of-another ply in movement on the gonveyor. This means consists of a pair of gripper-members 123 and 124 carried on laterally extending track means 125. There'may be provided suitable means for causing a-timed closing and opening action of the grippers when they are above a. support, such as a table 126, and above a conveyor, such as 127, respectively; and also for causing the reciprocation of the gripper unit on the track means.

.There may also be utilized an arrangement such. as that forming the subject matter of the above mentioned application of Ericsson H. Merritt, Serial No. 594,011, filed February 19, 1932, one form of which is exemplified in Figure 10. This. arrangement comprises a. plurality of vacuum cup members 130 forming part of a unit 131 which reciprocates on track means 132. The vacuum cup members may be connected with a suitable evacuating means, not shown,'by means of conduits 133. M'echanismof any well known or suitable -type,may be provided for timing the evacuation of the cup members and the restoration of normal pressure therein, and for the timing ofthe reciprocation of the unit. As will be seen the unit acts to lift plies one by one from a stack-134 andto deposit or set the same on a conveyor 135 or on a ply carried thereon. Elevator means, as indicated at 135', is preferably provided to progressively lift the .stack as plies are removed therefrom. As above .set forth, it is of importance in. many, instances that the pressure reach the glue line before heat has affected the adhesive.

material thereat. At the same time it is desirable that the effect of heat on the adhesive material be not unduly delayed so as to unnecessarily retard the process with a resultant necessity for greater total press area.

instances perforated sheet metal or wire mesh 'cauls may be advantageously utilized. The use of the latter permits the venting of the .assembly,for example, as set forth in my copending application Serial No. 454,832, filed May 22, 1930 as, for example, in instances where a relatively large amount of water or other liquid is employed.

In Fig". 12 there iseXemplified an assembly comprising a core 136, face and back plies 137 and 138, and sheet metal cauls 139 and 140. Then such an arrangement is placed in a hot press, the penetration of heat to the glue lines is retarded just enough by the interposed metallic members to permit the full application of the pressure, whereupon the heat is conducted rapidly through the caul members to the assembly so that there is no further delay in the heating of the adhesive material at the glue lines. In the practice of this feature of the invention, and as exemplified in Fig. 11, a metal caul 140 may be first laid upon a conveyor such as 141, a back 138 disposed thereupon, and the upper, surface of this ply coated as by being moved under a disseminating arrangement such as an atomizer 142, a rotating brush 143 and an on top of the face 137. The completed ar-- rangement may then be delivered to suitable hot press mechanism and thereupon pressed. For example, it may be moved between endless belt pressure members 145 and 146 for which suitable heating means are provided.

As another example of a manner of providing a coating of a powdered adhesive materialon surfaces to be joined, mention may be made of passing a surface to be lued through a mass of adhesive particles. or instance, (Fig. 13) a pair of narrow belts 147 and 148 may be arranged'to grip the edges of a core 149 and pass it into and through a mass or heap 150 of particles in such manner that the particles will adhere to the sides of the core. The surfaces of the core are preferably moistened and the particles of the mass maintained in a dry state. After the core has been moved through the mass,' face and back plies may be associated Willha the coated surfaces thereof in any suitable manner and the assembly passed to pressing means in a desirable manner, such, for example, as one of the manners exemplified herein.

To further facilitate an understanding of the mannerin which the time, temperature, and pressure or moisture content factors may be desirably controlled in a particular operation conducted in accordance with the invention, there is given below data for one mode of procedure in providing three-ply panels from rotary cut, yellow birch plies, each onesixteenth inch thick, in a commerciall dry state, each ply measuring 38 inches y 90 inches.

Character of adhesive material 50, parts 80 mesh caSe1n 50 parts dry spray process blood- 10. parts lime Amount of adhesive material per 1,000 square feet of double glue line area 19 ,5 pounds Amount of water per 1,000 square feet of doubleglue line area 37 pounds Time interval between the starting of initial coating of :1 ply in an assembly and the completion of the assembly 1 minute and 30 seconds Time interval between the completion of an assembly and the initation of the bonding operation 30 seconds Pressure applied 1 200 pounds per square inch Temperature at the face of the pressure elements 258 F. Duration of the bonding operation 1 minute Time interval between the completion of the bonding operation and the initiation of a succeeding finishing v operation 5 minutes Panels made up by a procedure conducted 1n accordance with the inventlon under the conditions set forth immediately above, wherein two plies of each assembly wer coated on a surface, and wherein each of these phes was first passed throu h a spray from which 1t received 9% poun s of water per thousand square feet of area coated, then through a ,zone wherein it received 9% poundsof the dry adhesive set forth per thousand square feet of area coated, and then through a spray wherein it received 9 lbs. of water per thousand square feet of area coated, showed an average of 47 0 pounds in dry shear tests, and an average of 269 pounds in wet shear tests after soaking for 48 hours in cold water.

By Way.of example, further reference is made to a continuous type ofoperationwhereas for instance, hot rollers or heated caterpillar type belts, for example. Reference is made to one instance wherein dry fir-wood veneer is fed to an assembly conveyor and is carried along under an atomizer, and water applied in a fine spray to the exposed surface, the amount of water being about 25 to 30 lbs. per square foot of ply surface. The ply surface is next carried under a distributor for powdered adhesive, 9. dry composition of 52.5 parts soluble blood albumen and 57.5

parts soya bean fiour, 17 parts of hydrous trisodium phosphate crystals, and 15 parts of hydrated lime being dusted on as the surface travels along. The composition may be ground to about 80 mesh and spread at a rate of 20 to 25 lbs. per thousand square feet of ply surface. Another plyis superposed on this prepared surface, moisture is supplied by a further atomizer head, and then an adhesive applicator dusts on the adhesive, and another wood ply is in turn superposed. The assembly is then forwarded througha heat and pressure applying zone in the form of opposed caterpillar type belts and about two minute treatment is had at 270 F., and a pressure of about 200 lbs. during transit. The panels then proceed through a cooling zone and into a double deck sanding machine to sand and smooth down the surfaces. Edge-trimming completes the product, and the panelsmay then be sorted on a sorting and grading conveyor.

There is thus provided a'continuous procedure utilizing blood in connection with soya bean flour, by means of which ply wood may be produced in a particularly eflicient v and effective manner under desirable conditions and with a relatively high degree of uniformity in the product. Since the soya bean flour is an adhesive 'materialof a nondispersible character, the penetration of the blood is desirably controlled as set forth in applicants copending application, Serial #455,978, above referred to. As there set forth, other adhesives may be substituted for thosespecified. For example, soya bean flour I may bdreplaced by other oil seed flours, by

isolated protein therefrom, or. by casein.

In similar continuous procedure, adhesive bases of different composition may also be employed. For instance a protein also in non-dispersed or discrete particle form, asv soya bean flour 100 parts, with trisodium phosphate 10 parts, barium hydroxide 20 parts, and calcium hydroxide 17 parts. The surfac to be glued are supplied with the adhesive base in discrete particle form, and the assemblage may be passed through the hot-pressing'zone for instance for one to three minutes. If the sodium salt be omitted, the

longer period of heating is desirable in order to attain water-resistance. A good bond is bad in either case.

For the sake of facility of expression the I unrolling,

term squares is utilized herein to describe plies which are sufliciently short so that'they may be readily handled without rolling or regardless of their geometric shape.

Since certain changes in carrying out the above methods and in the constructions set forth, which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawings shallbe interpreted as illustrative and not in a limiting sense.

It is also to be understood that the follow-' ing claims are intended to cover all of the generic and specific features of the invention hereindescribed, and all statements ofthe scope of the invention which, as a matter of language, might be said to fall therebetween. Having described my invention, what I claim as new and desire to secure by Letters Patent isf d o 1. The method of forming plywo'od, which comprises continuously supplying an adhesive material in discrete-particle form and in uniform quantities to be received by mov- 'ing squares, moving squares along a path such that a surface of each square will receive said material during its movement, successively forming assemblies by a step which includes associating a square with the coated surface of each square which has so received said material, the sequential coating and associating steps being uniformly timed, and 'subjectingcthe completed assemblies to bondin'g conditions. i

2. The method of forming plywood, which comprises continuously supplying an adhesive material in discrete-particle form and in uniform quantities to be received by moving squares, moving'a series of squares one after another along a path such that a surface vof each square will receive said material during its movement, successively forming assemblies by a step which includes associating one of'another series of squares with the coated surface of each square which has so received said material, the sequential coatingand associating steps with respect to each of the squares of the first mentioned series being uniformly timed and each of said assemblies being completed in a uniform time interval, and subjecting each of the assemblies to bonding conditions for a. uniform time interval.

3. The method offorming plywood, which comprises continuously supplying an adh esive-materialin d screte-particle form and in one of another series of squares with the' coated surface of each square which has so received said material, the sequential coating and associating steps with respect to each of the uares of the first mentioned series being uniformly timed, initiating a bonding step with respect to each of said completed assemblies at uniform time intervals after the coating of their respective ones of the squares contained in the I first mentioned series, and continuing the bonding operation with respect to each of said assemblies for a uniform time interval.

a 4. The method of forming plywood, which comprises continuously supplying anadhe sive material in discrete-particle form and in uniform quantities to be received by moving squares,cmoving a series of squares one after another along a path such that a surface-of each square will receive said material during its movement, there being suitably provided a liquid whereby the adhesive will be affected in situ successivel forming assemblies by a step which includes associating one of another series of squares with the coated surface of each square which has so received said material, initiating a bonding step with respect to each of said completed assemblies at a time not greater than 5 minutes after the coating of the square of the first-mentioned series contained therein and less than sufiicient to complete-the efiect of the liquid on the adhesive.

5. The method of forming plywood, which comprises continuously supplying an adhesive material in discrete-particle form and in uniform quantities to be'receivedby moving squares, moving a series. of squares one after another along ,a path such that a surface of each square will receive said material during. its movement, successively forming assemblies by a step which includes associating one of another series of squares with the coated surface of each square which has so received said material, the sequential coating and associating 'steps with respect to each of the squares of the first mentioned series being uniformly timed, subjecti g each of said as 'semblies to heat an pre ure at a uniform time interval after t e coating of the respective onesiof the squares contained in the firstmentloned series, and maintaining each of o said assemblies under heat and pressure for a uniform time interval under conditionssuch that the quantity of vaporizable material in the pressed panel is not reduced a substantial amount below the quantity of vaporizable material in the or ginal squares.

6. The method of forming plywood, which comprises concurrently supplying a heat set- -able adhesive material in discrete-particle form to surfaces to be united and assembling surfacesto be united in the presence of vaporizablemateriahand subjecting the assembled surfaces to heat and pressure for a period not substantially exceeding one minute, the heat applied being sufiicient to set the adhesive but insufiicientto generate bursting pressures within the assembly great enough to rupture the bond upon the release of pressure, said operations being conducted under conditions such that the quantity of vaporizable mate: rial in the pressed panel is not reduced a substantial amount below the quantity of vapor izable material in the original plies.

7. The method of formmg plywood, which comprises continuously supplying an adhesive material in discrete-particle form and in uniform quantities to be received by moving squares, moving a series of squares one after another along a path such that a surface of each square will receive said material during its movement, successively forming assemblies by a step which includes associating one of another series of squares with the coated surface of each square which has so received said material, each of said assemblies being completed in a'uniform time interval, an moving each of said completed assemblies to bonding mechanism, each of said movements occupying a predetermined time interval after the initial coating of a square contained therein, "and subjecting each assembly to bonding conditions for a uniform time interval. 8. The method of forming plywood, which comprises continuously supplying an adhesive material in discrete-particle form and in uniform quantities to be received by moving squares, moving a series of squares one after another along a path such that a surface of each square will receive said material .during its movement, successively forming assem blies by a 'step which includes setting another square upon ea'ch'coated square at a given point in its movement along said path, and subjecting the completed assemblies to bonding conditions.

9. The method of forming lywood, which comprises continuously supp ying an adhesive-material in discrete-particle form and in uniform quantities at a position to be re-- ceived by moving squares, moving a series of squares one after another along a path such that a surface of each square will receive said material during its movement, associating with each coated square as its movement position, completing each vassembly, and

thereafter subjecting each assembly to heat and pressure, the heat and pressure applied 20 the two sides of each assembly being uniorm. v v

' 10. The method of forming plywood, whichcomprises continuously supplying an adhesive material in discrete-particle form and in uniform quantities at a position to be received'by moving squares, moving a series of squares one afteranother along a path such that a surface of each square will receive 7 said material during its movement associating with each coated square as itsm'ovement continues one of a series of other squares to form a partial assembly, continuously supplying adhesive material in discrete-particle form and in uniform quantities at a position to be received by moving partial assemblies,

moving said partial assemblies one after another as they are formed along a path such that a surface of each artial assembly will receive material at sald second mentioned position," completing each assembly, each assembly being completed in a uniform, time interval, moving each completed assembly to a bonding .mechanism, each movement occupying a predetermined time interval after the initial coating of a square contained therein, and subjecting each assembly to bondilngconditions for a uniform time interva- 11. The method of forming plywood, which.

comprises continuously and concurrently applying an adhesive material indiscrete-particle form to the surfaces of the squares to be united and assembling such surfaces, each assembly being built up on one of a series of squares moving one after another at a given speed, moving each assembly at a higher speed after its completion to separate said assemblies, delivering each of the assemblies thus separated to non-progressivebonding mechanism in a uniform time interval after.

the initial coating of a square contained therein, and subjecting each-assembly to bonding conditions for a uniform time interval without movement of the assembly.

- 12. The method of forming plywood, which comprises moving a series of squares one after another along a given path, applying an adhesive material in discrete-particle form to each of said squares at a given point in said path, disposing another square on each coated square at a second point in said path, performing successive coating and assembly operations at successive points in said path, moving each completed assembly at a higher speed at a further point in said path to separate the assemblies, delivering each of the assemblies thus separated to non-progressive bonding mechanism in a uniformtime interval after the initial coating of a square contained therein, and subjectingeach of said assemblies'to bonding conditions for a uniform time interval without movement of the assembly. V 1

13. The method offorming plywood, which comprises continuously supplying an adhesive material in discrete-particle form in uni- 'rial during its movement, successively form- -by moving squares, moving a series of squares -form quantities at a position to be received by moving squares, moving a series of squares one after another along a path such that a surface of each square will receive said mateing assemblies by a step which includes associating with each coated square one of another seriesof squares, moving the assemblies so formed one after another in uniform time intervals after the initial coating of a square contained therein between pressure elements, and progressing the assemblies along between said pressure elements for a sufiicient period and under conditions to effect the bonding of the squares. 7 39 14. The method of forming plywood which comprises disposing of a series of squares one after another upon a conveyor, applying an adhesive material in discrete-particle form and to successive squares as they move along. on the conveyor, setting each of another series of squares one after another upon successive coated squares at a predetermined point in the motion thereof on the conveyor, completing each partial assembly thus formed, and progressing each assembly after it is formed between heated pressure elements .for a period of time sufiicient to bond the squares to form a completed panel. 15. The method of forming plywood which comprises continuously supplying an adhesive material in discrete-particle form in uniform quantities at a position to be received at a given speed one after another along a path suchthat a surface of each square will receive said material during its movement,

successively forming assemblies by a step which includes setting one of an additional seriesof squares upon each coated square at a given point in its movement, continuing the movement of each assembly to a point where it passes between pressure elements, and progressing each assembly along between said pressure elements for a sufiicient period to effect the desired bonding. said progression 7 being at the same speed asthe aforesaid movement. I

16. The method of forming plywood, which 115 comprises continuously supplying adhesive material in discrete-particle form and in uniform quantities to be received by squares, causing squares to receive coatings of said material, and successively forming assemblies, said operations being conducted in a continuous and concurrent manner wherein an assembly of squares is being formed while another square is being coated, and the successive coating and assembly steps being uni- 125 formly timed.

17. The method of forming plywood, which comprises moving along a given path one after another a series of plate-like elements, each of which is a good conductor of heat, 13') building up an assembly of relatively poor heat-conducting squares on each of said platelike elements during its movement, and sub jecting each completed arrangement to heat and pressure.

18. The method of forming plywood which comprises moving along a given path one after another a series of plate-like elements each of which is a ood conductor of heat,

.building up an assem ly on each of said platesand square feet of glue line area, conducting each assembly as it is formed to a pressing mechanism and immediately applying heat and pressure thereto, each of said assemblies being subjected to heat and pressure at a. uni: form time, after the initial coating of a square contained therein and being subjected toheat and pressure for a uniform time interval.

20. The metlfod of forming plywood which comprises supplying at a glue line between surfaces of materials having no excess of moisture an adhesive material indiscrete particle form, and also supplying a'plasticiz mg agentm an amount not substantially in excess of the amount required for effectmg the union, subjecting the adhesive material at the glue line to heat and pressure, and continuing the application of heat and pressure fora period not exceeding 1 minute". 21. The method of forming plywood which comprises associating surfaces to be joined in the presence of an adhesive-material in dlscrete-particle form and a plasticizing medium in a proportibn not greater than an equivalent of 30 pounds of water to one thousand square feet of glue line area, and sub ecting said surfaces to heat and pressure.

22. The method of forming plywood, which com risesaassociating surfaces to bejoined in t eprcsence of an adhesive material in discrete-particle form and a liquid in a proportion not greater than an equivalent of 25 pounds of water to 1,000 square feet of glueline area, and subjecting said surfaces to heat and pressure. 23. The method of forming plywood, which comprises applying adhesive material in discrete particle form to a surface to be incorporated, a liquid being also applied in a proportion not greater than an equivalent of 65 25 pounds of water to 1,000 square feet of hate powdered adhesive material, means surface area, assembling and" subjecting to heat and pressure;

24. vThe method of forming plywood, which comprises applying adhesive material in pow dered form to-a surface to be incorporated, a liquid'being also applied-in a proportion not greater .thanian equivalent'of 25 pounds of water to 1,000square feet of'glue line area and being applied in part before the application-of the adhesive material and in part after j its 1 application, "assembling I and subjecting to heat and-pressure; 1

25. The method fformin'g comprises continuously and concurrently ap-' plying an adhesive material in discrete-particle form to squares and formingassemblies including said squares, subjecting each-assembly to bonding conditions after an in terval not greater than 5 minutes after the initial coating of a uare 'ncludedtherein, and continuing s'aid-= nding op'eration for a period not exceeding! minute.

o 26. The method of gluing materi is which comprises applyin a plasticizing agentto a surface to be g ued, thereafter "applying an adhesive materialin powdered form to said surface, and thereafter applying a piss ticizing liquid to'saidsurfa'ce, and associatin with the coated surface a surface to be join thereto. 27. Apparatus for the formation of ply wood'compris'ing a conveyor for plies, means for applying a plasticizing-liquid to pliesmoving on said conveyor, means for applying a powdered adhesive material to pliesmoving onsaidconveyor', and a'seoondmean's for applying aplasticizing liquid to" plies moving on said conveyor, said applying means being arranged to operate in the order named.

wood, including spreading means arranged to disseminate powdered adhesive material,

conveyor means for moving-a square inposition'to receive on a 'sur a set a square on said conveyor means, 'means to convey the coated square away from sa d spreading means, meansxto dispose a second square 'upontli'e coated surface of a square being moved away from saidspreading the assemblies thus formed.

29. Apparatus for the formation of plywood, including spreading means arranged to disseminate powdered adhesive material,

conveyor means for movingasqua're in 'position to receive on a surface thereof a ma-' terral from said spreading means,-means to set a square on said conveyor means, means to convey the coated square away from said spreadmgmeans, means to set a'second square upon the coated surfacep of a vsquarebeingmoved away said spreadingv means, a

second spreading means arranged to dissemi- 28. Apparatus for the formation of p1y' ce thereof material from said spreading means, means 'to' lywood which if! ans, and bondingme'ohanism for receiving ill;

bon

thus formed.

move a partial assembly formed bythe previously mentioned means in position to receive an adhesive material from said second spreading means upon a surface thereof, means to convey the coated partial assemblyaway from said second spreading means, means to set a third square upon the coated surface of a partial assembly being moved awa from said second spreading means, and

mechanism for receiving assemblies 30. Apparatus for the formationof plywood, including spreading means arranged to disseminate powdered adhesive material,

conveyor means for moving a square in position to receive'on a surface thereof material from said spreading means, means to set a square on said conveyor means, means to convey, the coated square away from said spreading means, means to set a second square upon the coated surface of a square being moved away from said spreading means, a second spreading means arranged to disseminate powdered adhesive material, means to from said second mg operation progresses.

Apparatus for forming plywood, com-' pris ng means for conveying squares, autormatic means for setting squares successively and in close juxtaposition on said conveyingmeans ad acent the beginning of its active run, means beyond said setting means for disseminating a powdered adhesive material above said conveying means, means beyond the dissemmatiiig means for se ting another square upon each coated "squa e, a second means for disseminating a powdered adhesive material above said conveying means at a point beyond the last-mentioned means, means beyond said second disseminating means for setting an additional square upon eachcoated partial assembly, and means for subjecting to bonding conditions assemblies formed by the preceding means. 32. Apparatus for forming plywood, comprising means for conveying squares, automatic means for setting squares successively and in close juxtaposition on said conveying means adjacent the beginning of its active run, means beyond said setting means for disseminating a powdered adhesive material above said conveying means, means beyond the disseminating means for setting another square upon each coated square, asecond means for disseminating a powdered adhesive material abovesaid conveying means at a point beyond the last-mentioned means, means beyond said second disseminating means for setting an additional square upon each coated partial assembly, and a continuous pressing mechanism disposed beyond the aforesaid mechanism and arranged to progress the assemblies therethrough at a speed similar to the speed of movement of the conveyor. i

33. The method of forming plywood, which comprises successively applying an adhesive material in discrete particle form to the surfaces of squares while progressing them along, forming assemblies embodying coated squares concurrently with thecoating of other squares, and subjecting the assemblies to bonding conditionsconcurrently with the formation of other assemblies, the period between the initial coating of a square contained in an assembly and the completion of the assembly being uniform for all assemblies. i

34:. The method of forming plywood, which comprises successively applying adhesive material in discrete-particle form to the surfaces of squares while progressing them along, a liquid being applied in an amount not greater than 25 pounds per 1,000 square feet of glue line area, forming assemblies embodying coatedsquares concurrently with the coating of other squares, and subjecting the assemblies to bonding conditions concurrently with the formation of other assemblies, the period between the initial coating of a square contained in an assembly and the completion of the assembly being uniform for all assemblies.

7 35. The method of forming plywood which comprises progressing a series 0 squaresone after another along a path, applying adhesive material in discrete-particle form and in uniform amount to said squares at one stage of their travel along said path,

disposing an additional square upon each coated square at a further stagein its travel, applying to the exposed surface of each second square adhesive material in discrete-particle form and in a uniform amount at a further stage inthe travel of said squares along said path, disposing a third square upon each second square ata further stage of travel of said squares along said path, and subjecting assemblies to bonding conditions at a still further stage in the travel of said squares along said path.

36. The method of forming plywood, which comprises applying adhesive material in discrete-particle form to the surfaces of squares, a liquid being provided, forming assemblies each including at least one of said coated squares, and subjecting each of the assemblies to bonding conditions, the time 29 38. The method of forming 15 between the initial application of adhesive material to a square contained in an assembly and the initiation of the bonding operation being uniform with respect to such time in connection with they other assemblies.

plywood, which comprises applying adheslve material in discrete-particle form to the surfaces of squares, a liquid being provided, forming assemblies each including at least one of said coated squares, and subjectingeach of the assemblies to bonding conditions, the time between the initial application of adhesive material to a square contained in an assembly and the initiation of the bonding operation being uniform with respect to such time in connection with the other assemblies, and being insufiicient to permit the liquid to exert its full efiect.

39. The method of formihg plywood,

ac which comprises applying adhesive material in powdered form to the surface of a square,

a pla'sticizing liquid being provided independently of the adhesive, disposing another square on the coated square, and subjecting 40 an assembly including said squares to pressure and heat, the time between the initial coating of a square contained in said assembly and the initial application of pressure and heat being not greater than five minutes, and the application of pressure and -heat being for a period not substantially exceedin'g one minute.

i 4:0. The method of forming laminated structures, each containing a multiplicity of wood plies, which comprises utilizing in the formation of each structure plies having a' combined moisture content of materially less than 10% of the weight ot the structure,

applying to one of each pair of surfaces to be incorporated in each structure an adhesive material in discrete-particle form, supplying. also moisture in a total amount not.

stantially exceeding the difieren'ce between said combined moisture content and c0 -10%.of the weight of the structure, assembling and subjecting to heat and pressure. 41. The method of forming plywood,

whichcomprises continuously and concurrehtl applying powdered adhesive material and iquid to surfaces of commercially dry l squares 'and'forming assemblies 'each include ingat least one of said squares, said liquid being in 'an amount not. greater than the equivalent oftwenty-five pounds of water to one thousand square feet of glue'lline area, and subjecting each assembly to pressure and heat, the initiation of the bonding of no assembly being spaced more than five minutes after the initial coating of a square contained therein. t

42. The method of forming which comprisesapplying adhesive material in discrete-particle form to a surfaceto be incorporated, a liquid being also applied in a proportion not greater than an equivalent of 25 pounds of water to 1,000 square feet of surface area, assembling and subjecting to heat and pressure after an interval not greater than 5 minutes after the application of the adhesive material.

In testimony whereof I afiix-m signature. THEODORE WILLIAMg DIKE.

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