CA1055832A - Plywood manufacture using foamed glues - Google Patents
Plywood manufacture using foamed gluesInfo
- Publication number
- CA1055832A CA1055832A CA225,620A CA225620A CA1055832A CA 1055832 A CA1055832 A CA 1055832A CA 225620 A CA225620 A CA 225620A CA 1055832 A CA1055832 A CA 1055832A
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- Canada
- Prior art keywords
- liquid
- glue
- foamed
- plywood
- veneers
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
Plywood is made by continuously propelling a liquid plywood glue in unfoamed condition at a predetermined flow rate, continu-ously foaming the flue as it is propelled, and continuously ex-truding or otherwise applying the foamed glue to the surface of a plurality of wood veneers. The flow rate of the unfoamed and foamed glue is maintained substantially the same on a unit weight of liquid glue per unit time basis. The veneers then are laid up in-to a plywood assembly and pressed, whereupon the pressure breaks the fo?? and unites the veneers. The method is applicable gener-ally to the production of laminar products by the application of a foamed liquid to a solid surface.
Plywood is made by continuously propelling a liquid plywood glue in unfoamed condition at a predetermined flow rate, continu-ously foaming the flue as it is propelled, and continuously ex-truding or otherwise applying the foamed glue to the surface of a plurality of wood veneers. The flow rate of the unfoamed and foamed glue is maintained substantially the same on a unit weight of liquid glue per unit time basis. The veneers then are laid up in-to a plywood assembly and pressed, whereupon the pressure breaks the fo?? and unites the veneers. The method is applicable gener-ally to the production of laminar products by the application of a foamed liquid to a solid surface.
Description
5~i~32 PLYWO~D i~ Nr~lAC'~IIRE USING FOAMEI) GLI~ES
This invention relates to the flppl;cation of ro~med liquids to solid surfaces. It relates in pnrticul~r to the manu~acture of 21ywood by tne application of foamed ].iqu;d plywood glues to wood veneers followed by formin~ the veneers into a plywood assembly and pressin~ the assembly into a plywood panel.
In the classic method Or plywood manuracture~ wood veneers are coated with a suitable adhesive ln a ro:Ll coater, spray coater, or curtain coater. The veneers a.re formed înto a plywood assembly usin~ the desired layup pattern after which the assembly is cold pressed or hot pressed to set thfl glue and form the plywood panel.
Th.is procedure, though ancient and widely used, still is beset with troublssomo problems.
Although in order to shorten press times, it is deairable to spread the ~rlue on hot veneers, thls has not been possible because o.f rapid glue dryout and premature glue setting. As a consequence in the manufacture o~ hot press plywood, the anomalous and ineffic-; ient procedure has developed of heatlng the green veneer to dry it, cooling the hot dry veneer, spreadin~ it with ~lue and assembling, .
and then reheatin~ the resultin~ assembly to set the glue.
It has been impossible to spread the veneers wlth ~lues char-acterized by a de~ree of activity above a certain level. This :is for the reason that glue is helcl up in the roll coater, or overspray is recirculated in the spray or curtain coater, with the result that in each instance some of the ~lue applied to the veneers is old glue~ held in the system beyond the permissible time allowance.
In the roll coater, it is impossible accurately to control the applied glue spreads. The spread is influenced by veneer th-ickness and veneer surface qualities. These are variable factorsO
Since press times are relatively lon~, the output of a ~iven mill is determined not b~r the time required for assemblin~ the veneers~ but rather by the capacity Or its presses.
, , , ' In hot I)ress plywood rnanufacture, blistering and veneer over-he~ting are problems BecAuse of` the poor thermal conductivity of wood, it is necessary to overheat the exterior sl1r~cfls of the p~nels. This drives the moist1lre to the center of the panel and causes blisteriny.
~ ,lue foaming, inade~uate pot lire an~ adver~se time-viscosity relRtionships present difricult problems.
Plant layup and press cycles are restrlcted by practical con-siderations of available equipment personnel, ~lue limitations, etc Glue is wasted by the necessity of overspreadin~ to compen-sate for thick and thin veneers and ~ e dryoutO
Methods of ~lue application are not corrolatod with new tech-nlques ~or mochanized layu~ and au-ton1atic plywood productionO
It is the ~eneral purpo9e of the present inventlon to provide method and apparatus for the manufacture of plywood and like pro-ducts which overcome the ~ore~oing problems.
In the accomplishment of this purp~se, a method is practiced which is the exact opposite in many important respects of the con-ventional method of making plywood.
In the conventional ~ethod, chemicals are added and procedures and equipment modiried to prevent the ~lue from foaming. In the present method it is foamed intentionally and performs valuable functions in the ~oamed conditionO
In the conventional method of hot pressing, thick veneers are disadvantageous since they insulate the glue line from heat. In the present method, thick veneers are desirable, or at least not disadvantageous since they provide a greater capacity for storing heat.
In conventional hot pressing the pre.ss time is a direct fun-ction of the thickness of the panel. In the present method, the press time is independent of panel thickness.
1~55~32 In ordinary hot pressing, prodwction capacity is / limited by the number of press openings available. In the present system, a single press opening can handle all of the -panels that possibly can be assembled during a given pressing cycle.
In conventional hot pressing, in order to heat the center of each panel, the exterior portions axe heated to temperatures above that required to cure the glue bond. This results in deterioration and panel blistering. In the present method, no por~ion of the panel need be heated above the glue-curing temperature.
In accordance with one broad aspect, the invention relates to the method of making a laminar product wh:ich comprises a) continuously propelling in unfoamed condition and at a predetermined 10w rate, a liquid comprising a liquid glue or liquid glue component, b) continuously foaming the liquid as it is propelled, c) continuously extruding the foamed liquid on the surface of a first sheet at a predetermined flow rate of foamed liquid and predetermined rate of traversal of extruded foamed liquid and surface relative to each other, d) applying a second sheet to the foamed liquid on said surface, e) at least one of said sheets being a porous cellulosic sheet, and f) pressing the resulting assembly under conditions predetermined to break the foam and create a substantially unfoamed glue bond uniting the sheets.
In accordance with another aspect, the invention relates to foamed liquid applying apparatus, an extruder which comprises: a) a laterally elongated ~irst chamber, b) means for connecting the ~irst chamber to a source of foamed liquid under pressure, c) a lat~rally elongated second chamber, having a plurality of extrusion openings along its length, ' '~
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d~ conduit means interconnecting the first and second chambers substantially throughout their lengths~ and e) valve means disposed in the conduit means for varying the flow oE liquid selectively into different lateral portions of the second chamber as required to produce a predetermined flow of liquid through the extrusion openings.
The flow rates of the unfoamed and foamed liquid are maintained substantially the same on a unit weight o~ liquid per unit time basis and the foamed liquid can be applied to the surface by extruding it thereon in the condition of a substantially continuous film.
The manner of practicing the present invention will be apparent from the accompanying specification and cla:ims considered together with the drawings, wherein:
Fig. 1 is a schematic view illustrating a plywood manufacturing line incorporating the presently described method and apparatus;
Fig. 2 is a schematic view of liquid foaming apparatus, such as may be incorporated in the plywood manufacturing line of Fig. l;
Figs. 3 and 4 are located on the sheet with Fig. 1 and are views in longitudinal and transverse section, respectively, Fig. 4 heing taken along line 4 ~ of Fig. 3, both illustrating the construction and manner of operation of a liquid foaming unit which is one of the elements of the foaming system of Fig. 2;
Figs. 5, 6 and 7 are views in longitudinal section, bottom plan, and -transverse sectionl respectively, of a foamed liquid extruding llnit such as may be employed in the systems of Figs. 1 and 2;
Figs. 8 and 9 are fragmentary detail views in plan and 1, ~ -3a--.
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end elevation, respectively, of a wood veneer sheet upon which foamed liquid glue has been extruded in accordance with the method of the present invention.
~ igs. 10, 11 and 12 are views in foreshortened side elevation, partly in section, transverse cross section, and longitudinal cross section, respectively, of an alternate foamed liquid extruding 3a -3b-.
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~ead which may be employed in the systems of Figs. l and 2; and Figs. 13 and 14 are views in foreshor~ened side elavation and transverse section, re~pectively, of still another extruding head applicable to the purposes of the invention, Fig. 14 being located on the sheet with Fig. lO.
In Fig. 2 there is illustrated schematically apparatus by means of which a liquid glue such as a conventional water base plywood glue, a liquid glue component, or other liquid may be converted to a form useful in the practice of the presently described method.
The liquid is fed by infeed lines lO, l2 into a unit 14 which may comprise a storage tank, or an inline mixer.
It is a particular feature of the invention that it Lends it-... .
self to the inline mixing of the components of the liquid to befoamed. In this application, the component ingredients ~ the liquid are fed, each at its appropriate rate into an inline mixer of suit-able d~31gn. This initiates the flow of liquid lnto the line toward the foamer.
The use of inline mixing has the advantage that the liquid is always freshly mixed and of constant age when it reaches the foam-20 ing unit, and also when it reaches the surface to which it is to beapp~ed. In the manufacture of plywood, this makes possible the use of formulations not operable in conventional procedures because of short plywood glue pot life. It also contributes to ~miform glue-spreading because the glue always is at the same age when it arrives at the spreading station.
In some instances the liquid components may be proprtioned directly into the line with the object in view of permitting the -downstream foaming unit to accomplish the mixing.
Whether the liquid is prepared batch-wise, by means of an in-30 line mixer, or by being direc~ proportioned into the line~ itnext is propelled through the system at a predeterminedl constant rate.
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In the illustrated fo~m of the invention, the llquid contained in unit 14 i9 drawn into line lh by ~e~rls of a positive displace-ment pump ]8~ Th;s key unlt of the a~sembly ~ay co~prise a ge~r pum~ of suitable design eauipped w;th a tachometel 20 capa~)le of ; indic~ting accurately the pump output.
The pump is driven at the desired rate bJ- means of a motor 22 connected to the shaft of the pump through a varlable speed trans-mission 24.
Line 16 also include~ a strainer Z6 and a branch line 28 with control valve 30. Line 28 may be used to introduce into the flow at a controlled rate a materi~l whlch cannot be introduced into unit 14. Such a material might comprise~ for example, a catalyst to be mixed with a plywood ~lue. Slnce it i~ introduced into the system ~ust before the foamer, only a rew seconds elapse between th~ tlrne of introduc,tion and the tirne of application. Thi~ interval ; i9 SO short that thc added mat,erial does not exert an adverse in-fluence, even though it may be highly reactive.
The metered liquid next passes through a three-way valve 32.
In the exemplary embodiment, valve 32 is controlled by an air c~Jlinder 34. In the first position of the valve th~ pumped liquid i9 shunted to a by-pass line 36 which recirculates it through the pump~ In the second position of the valve, the liquid is directed khrou~h llne 38 to the foaming unit l~0.
Foaming unit ~0 is ~acketed and supplied with temperature con-trol water through an inlet line L~2, with control valve 44, and an outlet line 46. It thus is possible to control the temperature of ; the foamed liquid to whatever level is indicated by the pro~erties of the liquid and the conditions of its foaming.
Air, nitrogen or other suitable gas is introduced under pres-sure into foaming unit 40 through line L~8~ Its pressure and amountare controlled by a regulator valve 50, a needle valve 52J and a pressure gauge 54.
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1a~5S8.~Z
The roa~1ng unit is powered ~y a motor 56 which drives the shaft 58 Or the unit through a belt and pulley a~sembly 60 The control of the amount of air supplied to foaming unit 40 -is important, In ~eneral, as much air is supplied to the foam:Lng unit as the liquid will accept. This in turn depends upon the ~.
nature of the liquid an(l the manner of operation of the foaming unit. If too much air is introduced, a non-uni~orm ~oam is produced in that it contains pockets of air which escape :~rom the foam as undesirable large bubbles when the foam is relea~ed ~rom the system, ~ :~
In ~eneral, in the manufacture of foamed plywood ~lue usin~
the system of Fig. 2, the relative amounts of ai.r and liquid ad~
mitted to the foaming unit are re~ulated in such a manner as to produce a foam havin~; a wei~ht to volume ratio of from 0.20 to 0.2~ ~:
: ~ra~ls per cc. Since the unfGamed li.quid ~lue has a density of about ~ .
1.1~, the net ef.~ect is to expand the glue to from l~ to 6 times its original volume by converting it to a foam.
Since the foamed product is driven by the positive drive of pump 18, it moves out of the foaming unit at the same rate that it enters, in terms of pounds per minute. However~ in terms of cubic inches per minute it moves out about five times as fast as it enters~
The .foamed liquid leaving foamin~ unit l~0 passes throu~h a line 62 which includes a temperature gauge 64 and a pressure gauge 66. :
Line 62 discharges the foamed liquid into an extruder 70.
Extruder 70 is equipped with a series of noæzles or jets 72 by means of whioh the foamed liquid i3 applied to a substrate~ It also is equipped with a discharge line 74 with valve 76 which dis-char~es waste material or wash water to the waste disposal system~
Extruder 70 is ~itted with valve means, to be described later, which re~ulates the ~low of foamed liquid to one or the other of these dischar~e systems. The valve means is controlled by an air cyli~br 78 connected in parallel to the same piping whi.ch supplies . , 1 ",, : . .
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alr under preY~ure to cylind0r 3).~. The flow o~ air to both cylin~
ders is controlled by a valve 80.
Thus air under pressure paqse~ from a common line 82 to plpe~
84 supplyin~ cylinder 34, and to pipes 86 supplying cylinder 78.
Jhen valve 80 is adJusted to one of its pos.itions~ cylinders 3L~, 78 initiate the flow of liquid throu~h foaming unit l~0 and extrud- :
ing head 70 simultaneously. When the ~alve is adjuclted to i-ts sec-ond position, the flow of llauid throu~h foamer ~0 and foamed li-quid throu~h extruder 70 qiml1ltaneously are cut offO This insures positive control of the system.
The construction of a suitable foaming unit 40 is shown in ~reater detail in Figs. 3 and 4.
As noted above, the foamin~ unit has for its ob~ect the con-version of liquid introduced throu~h line 38 i.nto a foam which i9 .~u~ficiently stabl~ so as not to break nor collapse si.~rnifican-tly, nor to change volume si~ni:flcantly for reasons other than pressure or temperature di~ferentials existing inside and/or outside the extruder, ac~ it is propelled to the extruder and also durin~ ex-trusion; i,e. it obe~s the ~as laws. The herein described foaming unit has the virtue of accomplishin~ this result rapidly, on a coh-tinuous hi~h volume basis, and with the production of a foam of remarkable stability from a wide var;ety of liquids.
The ~oamin~r unit basically comprises an outer case or stator 80 and a rotor 82.
St~tor 80 may be generally cylindrical in contour. It is pro-vided with a water jacket 84 fed with coolin~ water throu~.h infeed water line 42 and outfeed water line 1~6. It also is provided with connections for liquid infeed line 38, liquid out~eed line 62 and air infeed line 48.
The stator is hollow and provided around its inner periphery with a pluralîty of spaced recesses 86.
Rotor 82 is mounted on shaft 58~ driven by motor 56. The ~7--~OS~i832 sh~t is suprorted at one end of the rotor by means of a stout bearin~ 88 cont~ined in a bearin~ housin~ 90, bolted to one end of vtat or 80 .
Rotor 82 is cylindrical in outlinv~ and dimensioned to be re-ceived within the hollow stator, with a suitable clearance, for example a clearance of about l/16 inch~ being present between their respective surfaces.
The outer peripheral ~urface of the rotor i~ ~ormed with a plurality of recesses 92. These are spaced in a pattern corres-ponding to thvQ pattern o~ the recesses 86 in the stator, so thatdurin~ the rotation of the rotor, the recesses in the surfaces of rotor and stator momentarlly sweep across each other~
The net result i9 to provide an almost ex~losive agitation o~
tho llquld and ~as lntroduced into the ~oaming unit, As the liquid enter~ throu~h line 3~ at one end of' th~v unlt it is mixed with a metered amount Or air entering throu~h line l~a. The two components then pass through the unit in the direction of the axis o~ rotation of the rotor and exhaust via line 62~ As they traverse the unit they are subjected to violent agitation of the character described which results in the lar~e scale, rapid production of a stable foam.
In the alternative, recesses 86, 92 may be replaced by longi-tudinally extanding ~jrooves in the respective surfaces of rotor and stator.
The construction of A suitable extrudin~ unit 70 is shown in detail in Figs. 5, 6 and 7.
The extruding unit comprises a case or head 96 of the desired contour. Where the extruder is to be used in the application of plywood ~lue to a wide sheet of wood veneer, the case may have a length determined by the width of the veneer sheet and a width determin0d by the dimensions and number of the extruding nozzlesO
Case 96 is closed on the top and on all four slcLes9 but open .
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on the bottom. Its lorlgitudinal ~ide walls are provided with re-tainer ~trip~ 98. ~xtending outwardly rro~ its lower mar~ins are lon~itudinal ~langes 100.
A heavy plate 102 is detachably mountecl on the lower side of the case, opposite its lower open end. The plate may be variously retained in position, but as shown, may be retained by ~eans o~
- an~le irons 104 secured by bolts 106 penetrating flanges 100.
Plate 102 mounts a plurality of extrusion nozzles 72, Flgs. 2 and 5. These are dimen~ioned and shaped as desired to determine the size and contour of the extruded filaments of foam~d liquidO
For many applications they desirably may be round in cross section~
They are arranged preferably in two rows in staggered relation to provide a complete coverage of extruded material on the substrate on which the material is to be appliod.
Valve means havin~ th~ virtue of positively startln~ and stop-plng the flow o~ extruded mnterial throu~h the nozzles is provlded.
In the illustrated form of the invention9 such means comprises a sliding valve plate 108 having perforations 110 spaced and dimen-sioned to register with discharge nozzles 72. Valve plate 108 is slidably maintained in position between the upper surface of plate `-102 and the lower sur~aces of flanges 98.
It is adjustable between two positions. To this end the pis-ton rod 112 of cylinder 78 extends through a side wall of case 96 ' and is con~ected to a lug lll~ extending up~larclly from one end of -~
,, plate 108. Cylinder 78 adjusts the valv~ plates between a valve open position in which perforations 110 through the plate register with nozzles 72, and a valve closed position wherein the two sets of openin~s are out o~ registration with each otherO
Foamed liquid discharged throu~h nozzles 72 may be applied to a wood veneer sheet 118 conveyed beneath the extrusion head on a conveyor 120, Fi~o 2~
As related above, the pattern and s;ze and shape o~ the _9_ ;;
, .', ' ~ ' ~(~55133~2 extrllded mate~ial is determined by the arranEement, si7e and shape of tha axtrucli~f no~zles. A ty~)ical pattern and di~tr;but;ion u3e-ful in the manuf`actllre of plywood is illustrated in ~ rs. ~ and ~).
As sho~n in these two fip-lres~ where no7%1es 72 ~re round, the coherent ~oamad liquid is deposited in the form of filaments or rods 1l~0 of circular cross section. ~y virtue of the manner of applicationJ they extend substantially parallel to each other.
Their lateral spacin~ is detertn;ned by the lateral spacing of the nozz]es. In a typical instance it may run .from 1~8 inch to 1~2 inch. The diameter of the filamerlts may vary, for example ~rom 1/6L~ inch to 3/8 inch.
It is to be observed that where the filaments are circular in cross section, the contact bctween the under surface of the fil-aments and tho upper surrace o~ the substrnte is kopt at a minimùm.
'rhis ls lm~ort~nt because it redllces the tendenc~J of` wnl;er or other liqui~ to llow frorn the rilnments into the suostrate.
It also is to be observed -that the filaments are sufLiciently s-table so that they remain in their '~ 9 uncollapsed condition for a substan-tial period Or time9 This is important because it enables filaments of different reactive ma-terials to be applied to the same substrate, as will be discussed more fully hereinafter.
It fur-ther is to be observed that the foamed liquids of which the filaments are comprised do not f`low as do ~lu1(19. They are thixotropic and o~ very low density. Neither ~ravltational force nor momentum contributes much to their flow patterns. ~''or any given foamed liquid, the rate of flow through a speciflc opening will depend mostly on the shape of the openin,~ and the pressure differential between its entrance and its exit. E~ecause o the stability of the foam, it substantially maintains the contour of the extruder openings.
This property of foamed liquids creates a peculiar problem in the manufacture of plywood wherein the head employed for extruding the fil~ments usually is over four feet lon~ and may be over ei~ht ~ 10 ~IDS~3z fevt lon~i. In this applicatlon, ~1 extrllsion head havin~r the de-sL~n o.f that :i.l1ust.rated i.n r~'.ins~ 5, 6 and '7 -tends to dischar~;e foamed adhesive at di~ferent rate~ alorl~ its len~th. In Keneral,?
the rate o~ di.~char~.e is grreata~t ln the middle of the extrucling head and dlminishes tow~rd e~ch end to ~ minimurn occurrlng a 9p-aced distance inwardly from the ends of -the heacl. The rate of dis-char~e then lncreases observably toward the extreme ends of the head. This situation is disadva.ntageous in that lt re~ults in un-even application of foamed adhesive to the veneer surfaces~
~ 10 The ex-truslon heads illustrated in Figs. :L0 to 14 iriclugive overcome these problemsO Each in essence comprises two laterally elongated chambers which prererably lie Parallel to each other.
The foamed li~uid i3 piped into one of`-these chambers ~nd the ex-trus;on openin~ reed out from the other one.
The two chnmbors are connected along their lenp~h by condult means of such a nature -that the flow ~rom one chamber -to the other may be re~ulated independently along different portions of the :`:
chambers. This in turn controls the dischar~e from the extrusion .
; openings which accordingly may be rendered uniform along the width of the head.
In the embodiment of ~l~s, 10, 11 and 12, a discharge head, indicated generally at 70a, is illustrated in whlch -the two chambers ' are connected throu~h a slot~ e conduit in two sectlons: a rirst section in the upper chamber and a communicatln~ second sec-tion in the second chamberO Means are ~rovided for adjustin~ the effective length of the first section and the effective width of the second sect;on thereby adjustin~ the flow from one chamber to . the other. This in turn controls the discharge f'rom -the oxtrusion '. openings in the second chamber.
The f'irst 'chamber 150 preferably is cylindr;cal and may be . fabricated from two len~?ths of pipe 152 the outer ends of which are closed and the inner ends Or which are connected to a T-con-nector 15L~ which communicates with feed pipe 62. The latter in ~055~3~
turn is connected to a sollrcfl o~ ~o~med liqllid ~Inder pressureO
The bott,or, of the pipe is l~rovided with a lon~ituclinal slot 156 which serves bot~ as a guideway and a9 tha rlrst sectlon Or the conduit bet~reen the two chambers.
~ leans are provided ~or adjusting the erfective lengtll of slot 156.
In the illustrated form of the ;nvantion such means comprise gate means which adjustably block off more or less of the end por-tions of the slotO
The ~ate means comprise cylindrical slides 158, one :Located at each end of chamber 150. Each s:Llde has a key 160 which is re-celved in a termlnal gui(leway ~ortion Or slot 156.
The lnterlor of eaoh slid:Ln~ gate m~mber hfl~ a th:reaCIe(l blirld opening 162 which receives a screw 164. The latter extoncls th-rough the end wall of chamber 150 and is fitted with a head 166 by means of whlch the screw may be turned. This adjusts corres-pondingly the lon~itudinal posit;on of the ~ate member within the chamber.
The effective open portion of slot 156 thus provides a con-duit section o~ v~riable width which interconnec-ts chamber 150 wi-th a cooperatin~ chamber 170~
Chamber 170 iY defined by a top which rnay comprise flanges 172 extending laterally outwardly from hollow cylinder 152, a pair of opposed channel members 174 which form side wallsg a per~orated bottom plate 176 and a pair Or end pieces 178. An upper seal 180 ls interposed between flanges 172 and channel members 17l~. A di-vided seal 182 is interposed between channel members 174 and bot-tom plate 176. A filtering screen 184 is interposed between the components Or divided lower seal 182~ It has for its function filterin~ out oversized solid particles which mi~ht interfere with the extrusion of the foamed liquid.
The entire chamber assembly thsn is demountably assembled by means of bolts 186.
~L~ 3 55!3 A plur~lity Or c~tru310n nozzle~ 190 are presEed $nto the perfor~tlon~ of' bottom plate~ 17~o In the illuatr&t~d rorrtl Or the lnvention, these ara arran~ed ln two ~t:~g~ered row~.
The ~low Or roamed liquid throu~h s~tru6ion nozzle~ 190 i8 cQntrollad ~n p~rt by ad ~u~tin~ tha length Or a10t 1569 It 1B
~ur' her controlled by housinF ~lthln ch~mber 170 a oondult ~ec'cion Or ~d~ustable wldtll whlch 5t~m~1UniCate8 ~lth slot 1560 Thi~ eonduit ~ectlon i~ derlned by a p~lr Or ~le~ible plato~
192 wh'ch ~y be ~ade Or nylon, tc~lon, or other inert, ~lexible materisl. The pl~te~ extend 3~bstsntially the ontir~ length Or chamber 170 ln l~terAll~f spaced relation, ror~nin6 a ~lot 193.
They are supported at their ands by terminal bolt~ 1~6.
The ~pacin~ betw~on the two plates determinea the rlow lnto the ch~mber, Thi~ ~pAalng 18 adJu~table alon~ the lcnEth Or the plates by ~uan~ Or ~ plurality o~ ad~u~tment bolt0 194 thre6dod into bo~es 196 extcnding l~terally outwardly ~rom the ~ontr~
portions Or ohannals 174. Thc ends Or bolts 194 bear a~in~t the outer side r~ces Or plates 192. The bolts ~re secured ~n their ~elected sd~u~tment po~ition~ by mean~ o~ lock nut~ 198~
The ontlra as~embly thus ~cts a~ ~ valve which controls the rlow and distrlbution o~ foamed liquid through the ~xtrud~n~ he~d ~B requircd to provide ~ predet~rmined or un1rorm di~ch~r~e through di~char~e opsnlnE~ 190.
Fo~med liquid under pres~ure ~upplied by pipe 62 ~ill8 ahamber l50 ænd p~8308 throu~h communi¢atin~ slots 156D 193 Into ch~.b~r 170~ ther. pa~98 through chamber 170 and out noxzle~ 190 ln a ~low controlled by the ~ettin8 0~ ~&te momber~ 158 ~hich d~term~ne the l0n~th ~ slot l56 ~nd the ~ttin~ Or scr~ws 194 ~hich d~term~ne the width o~ ~lot 193. Thls provld3s ~he d~s~red ~low p~ttern~
A si~l~r r~ult 1~ achi~v0d by oxtru.~ion he~d 7~b, ~he con-~truct$on o~ which la i1}UBtrAt0d in P~gs. 13 ~d l4, Fo~med liqu~d ~nd~r pr~9Bur~ $J ~ntroduced ~nto ~ rst, , ~ Trademark !
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~al55l332 laterally elon~ated chamber 200 which may be slmply constructed of a pipe 202 ritted with end walls 201~ and provided with a plurality of s~aced openings 20~, A second laterally elongated chamber 210 is defined by a per-forated upper plate 212, a perforate~ bottorn plate ~4, filler pl-ates 216, 218, a divided seal 220, and end pieces 222. A filter screen 224 is interposed between the components of divided seal 220. Upper and lower angle iron clampin~ members 226 with associa-ted bolts 228 demountably secure the component parts Or the chamber in their assembled condition, Discharge nozzles 230 are pressed into the perforati.ons pres-ent along the len~rth of bottom plates 214. These may be arranged in any desired pattern, for example i.n A sin~le row alon~ the len~th of the chamber.
As ln the case of the prevlously descrlbed embodiment foamed liquid passes from the first chamber into the second chamber thr-ou~h valved conduit means which permit selective adjustment of the flow rate in various areas along the length of the assembly. To this end there i9 provided a plurality of tubes 232, the upper ends of which are threaded into the openings of upper chamber 200, ~ and the lower ends of which are threaded into the openin~s of upper . :
i l~late 212 of low~r chamber 210, ; Valve means are provided ror controllin~: the flow through each tube 232 individually.
A simple means of achievin~ this purpose i9 to fashion tubes - 232 out of a ~le,~ible deformable material such as rubber or plas-tic and mounting on each tube a pinch clamp, not illustrated, by means of which the flow through the tube may be controlledO
A more durabl.e and precise valve means is that illustrated in the drawin~rsO
; Each of tubes 232 mounts a valve 23l~ which controls the ~low : of .foamed liquid throu~h the tube. The valve may be any one of ., .
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"
~L~SSi~32 various conventional valves. It may ba, for exa~pleJ a ~ate val~e operated by means o~ a screw 236.
Thus in the Fig5. 13 and 14 f`orm of the extrusion head foamed liquid fed under pressure via pipe 62 into chamber 200 pas~es th-rou~h tubes 232 into lower chamber 210 and thence throu~h extrusion openin~s 230 The amount of liquid discharged throu~h the openin~q is det-ermined by the settin~ of the individual ones of valves 234. Thu~
a uni~orm flow, or any deslred pattern of non-uniform ~low may be achieved along the len~th of the extrusion head.
The method of the invention is applicable to the production of laminar products from sheets of material at least alternate ones Or which are cellulosic in ch~racter, such as wood veneers, boards~
and paper and hence nre inherently porous. Its application to ply-wood manu~acture i9 illustrated in E~1~, 1.
Two wood veneor preheatin~ lines run at ri~ht an~les to each other, ~eeting at a common assembly station. One delivers core, center and back veneers to the assembly station. It comprises an infeed conveyor 120, a heater conveyor 122 and an outfeed conveyor 12l~. The second preheatin~ line comprises a similar conveyor sys-tem 128 laid out at ri~ht an~les to the ~irst.
lrhe rirst conveyor system conveys to the assembly station a plurality of core veneers 128 and of` back and center veneers 130~
Conveyor sy~-tem 126 conveys to the assembly station a plurality of ~ace veneers 132, As they travel along the conveyor system including conveyor units 120J 122, 124 the core veneers and back and center veneers ara preheated with suitable heating units 13l~. Preferably, the heat~n~ units comprise -in~rared heatin~ units capable of heating the veneers to a temperature of from 200 to 400 F. during their time o~ passa~e throu~h the heatin~ unit. Singly, the veneers may be heated to this temperature rapidly even though wood is a poor . .
, ~S5~3;~
concluctor o~ heat. The contrary is true ir it is attempted to heat the veneers in a stack during hot pressing.
As they tra~lel along con-veyor system 1267 face veneers 132 are preheated to thc same temperature level by means of heating elements 136.
Foamed ~lue is applied to core veneers 128 and back and center veneers 130. The application is made to the upper sur~ace only of ; these veneers. It is made by means Or an extruder head such as heads 70, 70a, or 70b of Figs. 2, 10 and 13, respectively. This head applies to the veneers a coatin~ of foamed ~lue 140 in a pat-tern determined by the size and dimensions Or the exkruding orifices. -No adhesive whatsoev~r is applied to the surfaces of face ven-eers 132.
~ t the ~ssembly station, the core, back, center and face ven-eers are co~osLted int;o a plywood fls~embly lL~2. This i'3 combined with other panel assemblies to form a press load which ;.9 trans-ferred into a press 144 and consolidated into plywood panels.
The press may be either a sin~le opening or multiple openlng hotpress, or a cold press. It is a feature of the ~nvention that by 20 preheating the veneers, it is possible to use a high capacity sin-gle opening cold press at a press time Or under 2 1/2 minutes and still bond the veneers efficiently into the finished panel.
Durin~ pressin~, under conventional plywood press conditions, the foamed condition of the glue changes, The foam breaks because of two factors which inherently are present in a plywood press.
The first of these is pressure, which breaks the component bubbles of the foam. The second is the mi~ration of the water out of the aqueous foamed glue into the porous wood of the veneers, particu-larly under the influence of heat. ~his necessarily destroys the foam. Glue lines then are formed between the veneers which set to unite them~
The method above described has several significant advantaEes, .
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-16- ~-. , , : , . , ~ . ~ .
l~SS1~32 ~ irst, a~ noted, since the v~nears are prehflated, press times are markedly reduced and plant capacity corre~pondin~l;ly increased.
Second, since the amount of glue applied to the veneers i9 independent of the veneer thickness, it may be predetermined acc-urately without the necessity of over application to insure an adequate bond.
Third, since the ~lue may be placed ~ccurately on the veneer surface, lt need not be spread over trim areas. This effectuates further savin~ of elue.
Fourth, since the foamed ~lue occupies a relatively lar~e volume, and since it isapplied in the for~ of filaments or rods having but a limited contact with the hot veneer surface, problems of ~lue dryout are minimized with con(omitant improvement in bond.
Fi~h, since but a very short time interval elapses between the intro~uction of the ~lue into the system and the pressin~ of the panels ln the pre3s, hl~hly reactive ingredients rnay be intro-duced directly lnto the ~lue Just before it enters the foamer.
Such an ingredient comprises for example a catalyst added to a thermosettin~ resin glue, or formaldehyde added to a blood glue.
Sixth, sinc~ the foamed glue may be applied in the form of di~crete, laterally spaced filaments or rods, multiple extrusion heads may be employed to apply filaments alternately comprising substances which when mixed react chemically with e~ch other. The mixin~ and reaction then will occur during the press cycle at which time the filaments will be flattened into contact with each other durin~ the co~pression and breaking of the foam to form the plywood glue lines.
This concept may be extended to situations wherein the ensuin~
reaction is exothermic. Where the reactants comprise a thermo-setting resin glue and a catalyst -thereforJ the two may be applied separately, intermingled in the press, with the ensuing reaction liberatin~ sufficient heat to set the glue. This may be accomplished ~05SI!33Z
without the application of heat from an ex-ternal sourc0 so that, for the first ti~e, hot press glues may be used in the manufacture of plywood without -the use of a hot press.
An example i9 a thermosettin~ re~inous condensation product of resorcinol and ~ormaldehyde used with a para~ormaldehyde catalyst therefor. Another example is a thermosettin~ resinous condensa- ~;
tion product of phenol and formaldehyde as one componentJ a thermo-~ettin~ resinous condensation product of acetone and fo~aldehyde as a second component, and a catalyst therefor as a third co~ponent.
'.0 Seventh, by the use of foamed ~lue as opposed to liquid glues it is possible to apply the glue by means of extrusion. Extrusion procedures are not easily applicable to liquid glues since the solid fillers and debris which the glues invariably contain tend to plu~ the small openin~s throu~h which the liquid ~lues necessarily must be extruded, By foaming the glue and hence by increasin~ ;
Its volume five-~old lt ls possible to employ extrus;on heads having apertures sufficiently larce to avoid this problem.
Eighth it is possible to control easily and accurately the amount of ~lue applied to the veneers. This may be accomplished in ;
20 a major degree by altering the speed o~ pump 18, or by alterin~ ! ' the speed of the conveyor systems conveying the veneers, or by ch-angin~ extrusion heads 70, or by a combination o~ these expedients Minor variations in spread may be obtained by taking advantage of the fact that the extruded ~llaments are stretchable. Because of this a surprisin~ly wide ran~e o~ spread rates can be had with a given extrusion aperture~ Within limits varying the rate of glue extrusion relative to the speed of veneer conveying merely causes the applied glue filaments to stretch slightly or condense slightly without breaking. The necessary co~trol for optimum ~lue utiliza-tion thus is achieved accurately and easily.
- A
This invention relates to the flppl;cation of ro~med liquids to solid surfaces. It relates in pnrticul~r to the manu~acture of 21ywood by tne application of foamed ].iqu;d plywood glues to wood veneers followed by formin~ the veneers into a plywood assembly and pressin~ the assembly into a plywood panel.
In the classic method Or plywood manuracture~ wood veneers are coated with a suitable adhesive ln a ro:Ll coater, spray coater, or curtain coater. The veneers a.re formed înto a plywood assembly usin~ the desired layup pattern after which the assembly is cold pressed or hot pressed to set thfl glue and form the plywood panel.
Th.is procedure, though ancient and widely used, still is beset with troublssomo problems.
Although in order to shorten press times, it is deairable to spread the ~rlue on hot veneers, thls has not been possible because o.f rapid glue dryout and premature glue setting. As a consequence in the manufacture o~ hot press plywood, the anomalous and ineffic-; ient procedure has developed of heatlng the green veneer to dry it, cooling the hot dry veneer, spreadin~ it with ~lue and assembling, .
and then reheatin~ the resultin~ assembly to set the glue.
It has been impossible to spread the veneers wlth ~lues char-acterized by a de~ree of activity above a certain level. This :is for the reason that glue is helcl up in the roll coater, or overspray is recirculated in the spray or curtain coater, with the result that in each instance some of the ~lue applied to the veneers is old glue~ held in the system beyond the permissible time allowance.
In the roll coater, it is impossible accurately to control the applied glue spreads. The spread is influenced by veneer th-ickness and veneer surface qualities. These are variable factorsO
Since press times are relatively lon~, the output of a ~iven mill is determined not b~r the time required for assemblin~ the veneers~ but rather by the capacity Or its presses.
, , , ' In hot I)ress plywood rnanufacture, blistering and veneer over-he~ting are problems BecAuse of` the poor thermal conductivity of wood, it is necessary to overheat the exterior sl1r~cfls of the p~nels. This drives the moist1lre to the center of the panel and causes blisteriny.
~ ,lue foaming, inade~uate pot lire an~ adver~se time-viscosity relRtionships present difricult problems.
Plant layup and press cycles are restrlcted by practical con-siderations of available equipment personnel, ~lue limitations, etc Glue is wasted by the necessity of overspreadin~ to compen-sate for thick and thin veneers and ~ e dryoutO
Methods of ~lue application are not corrolatod with new tech-nlques ~or mochanized layu~ and au-ton1atic plywood productionO
It is the ~eneral purpo9e of the present inventlon to provide method and apparatus for the manufacture of plywood and like pro-ducts which overcome the ~ore~oing problems.
In the accomplishment of this purp~se, a method is practiced which is the exact opposite in many important respects of the con-ventional method of making plywood.
In the conventional ~ethod, chemicals are added and procedures and equipment modiried to prevent the ~lue from foaming. In the present method it is foamed intentionally and performs valuable functions in the ~oamed conditionO
In the conventional method of hot pressing, thick veneers are disadvantageous since they insulate the glue line from heat. In the present method, thick veneers are desirable, or at least not disadvantageous since they provide a greater capacity for storing heat.
In conventional hot pressing the pre.ss time is a direct fun-ction of the thickness of the panel. In the present method, the press time is independent of panel thickness.
1~55~32 In ordinary hot pressing, prodwction capacity is / limited by the number of press openings available. In the present system, a single press opening can handle all of the -panels that possibly can be assembled during a given pressing cycle.
In conventional hot pressing, in order to heat the center of each panel, the exterior portions axe heated to temperatures above that required to cure the glue bond. This results in deterioration and panel blistering. In the present method, no por~ion of the panel need be heated above the glue-curing temperature.
In accordance with one broad aspect, the invention relates to the method of making a laminar product wh:ich comprises a) continuously propelling in unfoamed condition and at a predetermined 10w rate, a liquid comprising a liquid glue or liquid glue component, b) continuously foaming the liquid as it is propelled, c) continuously extruding the foamed liquid on the surface of a first sheet at a predetermined flow rate of foamed liquid and predetermined rate of traversal of extruded foamed liquid and surface relative to each other, d) applying a second sheet to the foamed liquid on said surface, e) at least one of said sheets being a porous cellulosic sheet, and f) pressing the resulting assembly under conditions predetermined to break the foam and create a substantially unfoamed glue bond uniting the sheets.
In accordance with another aspect, the invention relates to foamed liquid applying apparatus, an extruder which comprises: a) a laterally elongated ~irst chamber, b) means for connecting the ~irst chamber to a source of foamed liquid under pressure, c) a lat~rally elongated second chamber, having a plurality of extrusion openings along its length, ' '~
~5S~3'~
d~ conduit means interconnecting the first and second chambers substantially throughout their lengths~ and e) valve means disposed in the conduit means for varying the flow oE liquid selectively into different lateral portions of the second chamber as required to produce a predetermined flow of liquid through the extrusion openings.
The flow rates of the unfoamed and foamed liquid are maintained substantially the same on a unit weight o~ liquid per unit time basis and the foamed liquid can be applied to the surface by extruding it thereon in the condition of a substantially continuous film.
The manner of practicing the present invention will be apparent from the accompanying specification and cla:ims considered together with the drawings, wherein:
Fig. 1 is a schematic view illustrating a plywood manufacturing line incorporating the presently described method and apparatus;
Fig. 2 is a schematic view of liquid foaming apparatus, such as may be incorporated in the plywood manufacturing line of Fig. l;
Figs. 3 and 4 are located on the sheet with Fig. 1 and are views in longitudinal and transverse section, respectively, Fig. 4 heing taken along line 4 ~ of Fig. 3, both illustrating the construction and manner of operation of a liquid foaming unit which is one of the elements of the foaming system of Fig. 2;
Figs. 5, 6 and 7 are views in longitudinal section, bottom plan, and -transverse sectionl respectively, of a foamed liquid extruding llnit such as may be employed in the systems of Figs. 1 and 2;
Figs. 8 and 9 are fragmentary detail views in plan and 1, ~ -3a--.
~55~3~
end elevation, respectively, of a wood veneer sheet upon which foamed liquid glue has been extruded in accordance with the method of the present invention.
~ igs. 10, 11 and 12 are views in foreshortened side elevation, partly in section, transverse cross section, and longitudinal cross section, respectively, of an alternate foamed liquid extruding 3a -3b-.
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, , :, 1~55~3'~
~ead which may be employed in the systems of Figs. l and 2; and Figs. 13 and 14 are views in foreshor~ened side elavation and transverse section, re~pectively, of still another extruding head applicable to the purposes of the invention, Fig. 14 being located on the sheet with Fig. lO.
In Fig. 2 there is illustrated schematically apparatus by means of which a liquid glue such as a conventional water base plywood glue, a liquid glue component, or other liquid may be converted to a form useful in the practice of the presently described method.
The liquid is fed by infeed lines lO, l2 into a unit 14 which may comprise a storage tank, or an inline mixer.
It is a particular feature of the invention that it Lends it-... .
self to the inline mixing of the components of the liquid to befoamed. In this application, the component ingredients ~ the liquid are fed, each at its appropriate rate into an inline mixer of suit-able d~31gn. This initiates the flow of liquid lnto the line toward the foamer.
The use of inline mixing has the advantage that the liquid is always freshly mixed and of constant age when it reaches the foam-20 ing unit, and also when it reaches the surface to which it is to beapp~ed. In the manufacture of plywood, this makes possible the use of formulations not operable in conventional procedures because of short plywood glue pot life. It also contributes to ~miform glue-spreading because the glue always is at the same age when it arrives at the spreading station.
In some instances the liquid components may be proprtioned directly into the line with the object in view of permitting the -downstream foaming unit to accomplish the mixing.
Whether the liquid is prepared batch-wise, by means of an in-30 line mixer, or by being direc~ proportioned into the line~ itnext is propelled through the system at a predeterminedl constant rate.
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1(~5~1~3~
In the illustrated fo~m of the invention, the llquid contained in unit 14 i9 drawn into line lh by ~e~rls of a positive displace-ment pump ]8~ Th;s key unlt of the a~sembly ~ay co~prise a ge~r pum~ of suitable design eauipped w;th a tachometel 20 capa~)le of ; indic~ting accurately the pump output.
The pump is driven at the desired rate bJ- means of a motor 22 connected to the shaft of the pump through a varlable speed trans-mission 24.
Line 16 also include~ a strainer Z6 and a branch line 28 with control valve 30. Line 28 may be used to introduce into the flow at a controlled rate a materi~l whlch cannot be introduced into unit 14. Such a material might comprise~ for example, a catalyst to be mixed with a plywood ~lue. Slnce it i~ introduced into the system ~ust before the foamer, only a rew seconds elapse between th~ tlrne of introduc,tion and the tirne of application. Thi~ interval ; i9 SO short that thc added mat,erial does not exert an adverse in-fluence, even though it may be highly reactive.
The metered liquid next passes through a three-way valve 32.
In the exemplary embodiment, valve 32 is controlled by an air c~Jlinder 34. In the first position of the valve th~ pumped liquid i9 shunted to a by-pass line 36 which recirculates it through the pump~ In the second position of the valve, the liquid is directed khrou~h llne 38 to the foaming unit l~0.
Foaming unit ~0 is ~acketed and supplied with temperature con-trol water through an inlet line L~2, with control valve 44, and an outlet line 46. It thus is possible to control the temperature of ; the foamed liquid to whatever level is indicated by the pro~erties of the liquid and the conditions of its foaming.
Air, nitrogen or other suitable gas is introduced under pres-sure into foaming unit 40 through line L~8~ Its pressure and amountare controlled by a regulator valve 50, a needle valve 52J and a pressure gauge 54.
., ... ~ , ... . ,~.................. .
1a~5S8.~Z
The roa~1ng unit is powered ~y a motor 56 which drives the shaft 58 Or the unit through a belt and pulley a~sembly 60 The control of the amount of air supplied to foaming unit 40 -is important, In ~eneral, as much air is supplied to the foam:Lng unit as the liquid will accept. This in turn depends upon the ~.
nature of the liquid an(l the manner of operation of the foaming unit. If too much air is introduced, a non-uni~orm ~oam is produced in that it contains pockets of air which escape :~rom the foam as undesirable large bubbles when the foam is relea~ed ~rom the system, ~ :~
In ~eneral, in the manufacture of foamed plywood ~lue usin~
the system of Fig. 2, the relative amounts of ai.r and liquid ad~
mitted to the foaming unit are re~ulated in such a manner as to produce a foam havin~; a wei~ht to volume ratio of from 0.20 to 0.2~ ~:
: ~ra~ls per cc. Since the unfGamed li.quid ~lue has a density of about ~ .
1.1~, the net ef.~ect is to expand the glue to from l~ to 6 times its original volume by converting it to a foam.
Since the foamed product is driven by the positive drive of pump 18, it moves out of the foaming unit at the same rate that it enters, in terms of pounds per minute. However~ in terms of cubic inches per minute it moves out about five times as fast as it enters~
The .foamed liquid leaving foamin~ unit l~0 passes throu~h a line 62 which includes a temperature gauge 64 and a pressure gauge 66. :
Line 62 discharges the foamed liquid into an extruder 70.
Extruder 70 is equipped with a series of noæzles or jets 72 by means of whioh the foamed liquid i3 applied to a substrate~ It also is equipped with a discharge line 74 with valve 76 which dis-char~es waste material or wash water to the waste disposal system~
Extruder 70 is ~itted with valve means, to be described later, which re~ulates the ~low of foamed liquid to one or the other of these dischar~e systems. The valve means is controlled by an air cyli~br 78 connected in parallel to the same piping whi.ch supplies . , 1 ",, : . .
, ~SS83;~
alr under preY~ure to cylind0r 3).~. The flow o~ air to both cylin~
ders is controlled by a valve 80.
Thus air under pressure paqse~ from a common line 82 to plpe~
84 supplyin~ cylinder 34, and to pipes 86 supplying cylinder 78.
Jhen valve 80 is adJusted to one of its pos.itions~ cylinders 3L~, 78 initiate the flow of liquid throu~h foaming unit l~0 and extrud- :
ing head 70 simultaneously. When the ~alve is adjuclted to i-ts sec-ond position, the flow of llauid throu~h foamer ~0 and foamed li-quid throu~h extruder 70 qiml1ltaneously are cut offO This insures positive control of the system.
The construction of a suitable foaming unit 40 is shown in ~reater detail in Figs. 3 and 4.
As noted above, the foamin~ unit has for its ob~ect the con-version of liquid introduced throu~h line 38 i.nto a foam which i9 .~u~ficiently stabl~ so as not to break nor collapse si.~rnifican-tly, nor to change volume si~ni:flcantly for reasons other than pressure or temperature di~ferentials existing inside and/or outside the extruder, ac~ it is propelled to the extruder and also durin~ ex-trusion; i,e. it obe~s the ~as laws. The herein described foaming unit has the virtue of accomplishin~ this result rapidly, on a coh-tinuous hi~h volume basis, and with the production of a foam of remarkable stability from a wide var;ety of liquids.
The ~oamin~r unit basically comprises an outer case or stator 80 and a rotor 82.
St~tor 80 may be generally cylindrical in contour. It is pro-vided with a water jacket 84 fed with coolin~ water throu~.h infeed water line 42 and outfeed water line 1~6. It also is provided with connections for liquid infeed line 38, liquid out~eed line 62 and air infeed line 48.
The stator is hollow and provided around its inner periphery with a pluralîty of spaced recesses 86.
Rotor 82 is mounted on shaft 58~ driven by motor 56. The ~7--~OS~i832 sh~t is suprorted at one end of the rotor by means of a stout bearin~ 88 cont~ined in a bearin~ housin~ 90, bolted to one end of vtat or 80 .
Rotor 82 is cylindrical in outlinv~ and dimensioned to be re-ceived within the hollow stator, with a suitable clearance, for example a clearance of about l/16 inch~ being present between their respective surfaces.
The outer peripheral ~urface of the rotor i~ ~ormed with a plurality of recesses 92. These are spaced in a pattern corres-ponding to thvQ pattern o~ the recesses 86 in the stator, so thatdurin~ the rotation of the rotor, the recesses in the surfaces of rotor and stator momentarlly sweep across each other~
The net result i9 to provide an almost ex~losive agitation o~
tho llquld and ~as lntroduced into the ~oaming unit, As the liquid enter~ throu~h line 3~ at one end of' th~v unlt it is mixed with a metered amount Or air entering throu~h line l~a. The two components then pass through the unit in the direction of the axis o~ rotation of the rotor and exhaust via line 62~ As they traverse the unit they are subjected to violent agitation of the character described which results in the lar~e scale, rapid production of a stable foam.
In the alternative, recesses 86, 92 may be replaced by longi-tudinally extanding ~jrooves in the respective surfaces of rotor and stator.
The construction of A suitable extrudin~ unit 70 is shown in detail in Figs. 5, 6 and 7.
The extruding unit comprises a case or head 96 of the desired contour. Where the extruder is to be used in the application of plywood ~lue to a wide sheet of wood veneer, the case may have a length determined by the width of the veneer sheet and a width determin0d by the dimensions and number of the extruding nozzlesO
Case 96 is closed on the top and on all four slcLes9 but open .
': ' , ' , ' ' ', ~ss~
on the bottom. Its lorlgitudinal ~ide walls are provided with re-tainer ~trip~ 98. ~xtending outwardly rro~ its lower mar~ins are lon~itudinal ~langes 100.
A heavy plate 102 is detachably mountecl on the lower side of the case, opposite its lower open end. The plate may be variously retained in position, but as shown, may be retained by ~eans o~
- an~le irons 104 secured by bolts 106 penetrating flanges 100.
Plate 102 mounts a plurality of extrusion nozzles 72, Flgs. 2 and 5. These are dimen~ioned and shaped as desired to determine the size and contour of the extruded filaments of foam~d liquidO
For many applications they desirably may be round in cross section~
They are arranged preferably in two rows in staggered relation to provide a complete coverage of extruded material on the substrate on which the material is to be appliod.
Valve means havin~ th~ virtue of positively startln~ and stop-plng the flow o~ extruded mnterial throu~h the nozzles is provlded.
In the illustrated form of the invention9 such means comprises a sliding valve plate 108 having perforations 110 spaced and dimen-sioned to register with discharge nozzles 72. Valve plate 108 is slidably maintained in position between the upper surface of plate `-102 and the lower sur~aces of flanges 98.
It is adjustable between two positions. To this end the pis-ton rod 112 of cylinder 78 extends through a side wall of case 96 ' and is con~ected to a lug lll~ extending up~larclly from one end of -~
,, plate 108. Cylinder 78 adjusts the valv~ plates between a valve open position in which perforations 110 through the plate register with nozzles 72, and a valve closed position wherein the two sets of openin~s are out o~ registration with each otherO
Foamed liquid discharged throu~h nozzles 72 may be applied to a wood veneer sheet 118 conveyed beneath the extrusion head on a conveyor 120, Fi~o 2~
As related above, the pattern and s;ze and shape o~ the _9_ ;;
, .', ' ~ ' ~(~55133~2 extrllded mate~ial is determined by the arranEement, si7e and shape of tha axtrucli~f no~zles. A ty~)ical pattern and di~tr;but;ion u3e-ful in the manuf`actllre of plywood is illustrated in ~ rs. ~ and ~).
As sho~n in these two fip-lres~ where no7%1es 72 ~re round, the coherent ~oamad liquid is deposited in the form of filaments or rods 1l~0 of circular cross section. ~y virtue of the manner of applicationJ they extend substantially parallel to each other.
Their lateral spacin~ is detertn;ned by the lateral spacing of the nozz]es. In a typical instance it may run .from 1~8 inch to 1~2 inch. The diameter of the filamerlts may vary, for example ~rom 1/6L~ inch to 3/8 inch.
It is to be observed that where the filaments are circular in cross section, the contact bctween the under surface of the fil-aments and tho upper surrace o~ the substrnte is kopt at a minimùm.
'rhis ls lm~ort~nt because it redllces the tendenc~J of` wnl;er or other liqui~ to llow frorn the rilnments into the suostrate.
It also is to be observed -that the filaments are sufLiciently s-table so that they remain in their '~ 9 uncollapsed condition for a substan-tial period Or time9 This is important because it enables filaments of different reactive ma-terials to be applied to the same substrate, as will be discussed more fully hereinafter.
It fur-ther is to be observed that the foamed liquids of which the filaments are comprised do not f`low as do ~lu1(19. They are thixotropic and o~ very low density. Neither ~ravltational force nor momentum contributes much to their flow patterns. ~''or any given foamed liquid, the rate of flow through a speciflc opening will depend mostly on the shape of the openin,~ and the pressure differential between its entrance and its exit. E~ecause o the stability of the foam, it substantially maintains the contour of the extruder openings.
This property of foamed liquids creates a peculiar problem in the manufacture of plywood wherein the head employed for extruding the fil~ments usually is over four feet lon~ and may be over ei~ht ~ 10 ~IDS~3z fevt lon~i. In this applicatlon, ~1 extrllsion head havin~r the de-sL~n o.f that :i.l1ust.rated i.n r~'.ins~ 5, 6 and '7 -tends to dischar~;e foamed adhesive at di~ferent rate~ alorl~ its len~th. In Keneral,?
the rate o~ di.~char~.e is grreata~t ln the middle of the extrucling head and dlminishes tow~rd e~ch end to ~ minimurn occurrlng a 9p-aced distance inwardly from the ends of -the heacl. The rate of dis-char~e then lncreases observably toward the extreme ends of the head. This situation is disadva.ntageous in that lt re~ults in un-even application of foamed adhesive to the veneer surfaces~
~ 10 The ex-truslon heads illustrated in Figs. :L0 to 14 iriclugive overcome these problemsO Each in essence comprises two laterally elongated chambers which prererably lie Parallel to each other.
The foamed li~uid i3 piped into one of`-these chambers ~nd the ex-trus;on openin~ reed out from the other one.
The two chnmbors are connected along their lenp~h by condult means of such a nature -that the flow ~rom one chamber -to the other may be re~ulated independently along different portions of the :`:
chambers. This in turn controls the dischar~e from the extrusion .
; openings which accordingly may be rendered uniform along the width of the head.
In the embodiment of ~l~s, 10, 11 and 12, a discharge head, indicated generally at 70a, is illustrated in whlch -the two chambers ' are connected throu~h a slot~ e conduit in two sectlons: a rirst section in the upper chamber and a communicatln~ second sec-tion in the second chamberO Means are ~rovided for adjustin~ the effective length of the first section and the effective width of the second sect;on thereby adjustin~ the flow from one chamber to . the other. This in turn controls the discharge f'rom -the oxtrusion '. openings in the second chamber.
The f'irst 'chamber 150 preferably is cylindr;cal and may be . fabricated from two len~?ths of pipe 152 the outer ends of which are closed and the inner ends Or which are connected to a T-con-nector 15L~ which communicates with feed pipe 62. The latter in ~055~3~
turn is connected to a sollrcfl o~ ~o~med liqllid ~Inder pressureO
The bott,or, of the pipe is l~rovided with a lon~ituclinal slot 156 which serves bot~ as a guideway and a9 tha rlrst sectlon Or the conduit bet~reen the two chambers.
~ leans are provided ~or adjusting the erfective lengtll of slot 156.
In the illustrated form of the ;nvantion such means comprise gate means which adjustably block off more or less of the end por-tions of the slotO
The ~ate means comprise cylindrical slides 158, one :Located at each end of chamber 150. Each s:Llde has a key 160 which is re-celved in a termlnal gui(leway ~ortion Or slot 156.
The lnterlor of eaoh slid:Ln~ gate m~mber hfl~ a th:reaCIe(l blirld opening 162 which receives a screw 164. The latter extoncls th-rough the end wall of chamber 150 and is fitted with a head 166 by means of whlch the screw may be turned. This adjusts corres-pondingly the lon~itudinal posit;on of the ~ate member within the chamber.
The effective open portion of slot 156 thus provides a con-duit section o~ v~riable width which interconnec-ts chamber 150 wi-th a cooperatin~ chamber 170~
Chamber 170 iY defined by a top which rnay comprise flanges 172 extending laterally outwardly from hollow cylinder 152, a pair of opposed channel members 174 which form side wallsg a per~orated bottom plate 176 and a pair Or end pieces 178. An upper seal 180 ls interposed between flanges 172 and channel members 17l~. A di-vided seal 182 is interposed between channel members 174 and bot-tom plate 176. A filtering screen 184 is interposed between the components Or divided lower seal 182~ It has for its function filterin~ out oversized solid particles which mi~ht interfere with the extrusion of the foamed liquid.
The entire chamber assembly thsn is demountably assembled by means of bolts 186.
~L~ 3 55!3 A plur~lity Or c~tru310n nozzle~ 190 are presEed $nto the perfor~tlon~ of' bottom plate~ 17~o In the illuatr&t~d rorrtl Or the lnvention, these ara arran~ed ln two ~t:~g~ered row~.
The ~low Or roamed liquid throu~h s~tru6ion nozzle~ 190 i8 cQntrollad ~n p~rt by ad ~u~tin~ tha length Or a10t 1569 It 1B
~ur' her controlled by housinF ~lthln ch~mber 170 a oondult ~ec'cion Or ~d~ustable wldtll whlch 5t~m~1UniCate8 ~lth slot 1560 Thi~ eonduit ~ectlon i~ derlned by a p~lr Or ~le~ible plato~
192 wh'ch ~y be ~ade Or nylon, tc~lon, or other inert, ~lexible materisl. The pl~te~ extend 3~bstsntially the ontir~ length Or chamber 170 ln l~terAll~f spaced relation, ror~nin6 a ~lot 193.
They are supported at their ands by terminal bolt~ 1~6.
The ~pacin~ betw~on the two plates determinea the rlow lnto the ch~mber, Thi~ ~pAalng 18 adJu~table alon~ the lcnEth Or the plates by ~uan~ Or ~ plurality o~ ad~u~tment bolt0 194 thre6dod into bo~es 196 extcnding l~terally outwardly ~rom the ~ontr~
portions Or ohannals 174. Thc ends Or bolts 194 bear a~in~t the outer side r~ces Or plates 192. The bolts ~re secured ~n their ~elected sd~u~tment po~ition~ by mean~ o~ lock nut~ 198~
The ontlra as~embly thus ~cts a~ ~ valve which controls the rlow and distrlbution o~ foamed liquid through the ~xtrud~n~ he~d ~B requircd to provide ~ predet~rmined or un1rorm di~ch~r~e through di~char~e opsnlnE~ 190.
Fo~med liquid under pres~ure ~upplied by pipe 62 ~ill8 ahamber l50 ænd p~8308 throu~h communi¢atin~ slots 156D 193 Into ch~.b~r 170~ ther. pa~98 through chamber 170 and out noxzle~ 190 ln a ~low controlled by the ~ettin8 0~ ~&te momber~ 158 ~hich d~term~ne the l0n~th ~ slot l56 ~nd the ~ttin~ Or scr~ws 194 ~hich d~term~ne the width o~ ~lot 193. Thls provld3s ~he d~s~red ~low p~ttern~
A si~l~r r~ult 1~ achi~v0d by oxtru.~ion he~d 7~b, ~he con-~truct$on o~ which la i1}UBtrAt0d in P~gs. 13 ~d l4, Fo~med liqu~d ~nd~r pr~9Bur~ $J ~ntroduced ~nto ~ rst, , ~ Trademark !
`' ' ' ' ' .
~al55l332 laterally elon~ated chamber 200 which may be slmply constructed of a pipe 202 ritted with end walls 201~ and provided with a plurality of s~aced openings 20~, A second laterally elongated chamber 210 is defined by a per-forated upper plate 212, a perforate~ bottorn plate ~4, filler pl-ates 216, 218, a divided seal 220, and end pieces 222. A filter screen 224 is interposed between the components of divided seal 220. Upper and lower angle iron clampin~ members 226 with associa-ted bolts 228 demountably secure the component parts Or the chamber in their assembled condition, Discharge nozzles 230 are pressed into the perforati.ons pres-ent along the len~rth of bottom plates 214. These may be arranged in any desired pattern, for example i.n A sin~le row alon~ the len~th of the chamber.
As ln the case of the prevlously descrlbed embodiment foamed liquid passes from the first chamber into the second chamber thr-ou~h valved conduit means which permit selective adjustment of the flow rate in various areas along the length of the assembly. To this end there i9 provided a plurality of tubes 232, the upper ends of which are threaded into the openings of upper chamber 200, ~ and the lower ends of which are threaded into the openin~s of upper . :
i l~late 212 of low~r chamber 210, ; Valve means are provided ror controllin~: the flow through each tube 232 individually.
A simple means of achievin~ this purpose i9 to fashion tubes - 232 out of a ~le,~ible deformable material such as rubber or plas-tic and mounting on each tube a pinch clamp, not illustrated, by means of which the flow through the tube may be controlledO
A more durabl.e and precise valve means is that illustrated in the drawin~rsO
; Each of tubes 232 mounts a valve 23l~ which controls the ~low : of .foamed liquid throu~h the tube. The valve may be any one of ., .
. .
"
~L~SSi~32 various conventional valves. It may ba, for exa~pleJ a ~ate val~e operated by means o~ a screw 236.
Thus in the Fig5. 13 and 14 f`orm of the extrusion head foamed liquid fed under pressure via pipe 62 into chamber 200 pas~es th-rou~h tubes 232 into lower chamber 210 and thence throu~h extrusion openin~s 230 The amount of liquid discharged throu~h the openin~q is det-ermined by the settin~ of the individual ones of valves 234. Thu~
a uni~orm flow, or any deslred pattern of non-uniform ~low may be achieved along the len~th of the extrusion head.
The method of the invention is applicable to the production of laminar products from sheets of material at least alternate ones Or which are cellulosic in ch~racter, such as wood veneers, boards~
and paper and hence nre inherently porous. Its application to ply-wood manu~acture i9 illustrated in E~1~, 1.
Two wood veneor preheatin~ lines run at ri~ht an~les to each other, ~eeting at a common assembly station. One delivers core, center and back veneers to the assembly station. It comprises an infeed conveyor 120, a heater conveyor 122 and an outfeed conveyor 12l~. The second preheatin~ line comprises a similar conveyor sys-tem 128 laid out at ri~ht an~les to the ~irst.
lrhe rirst conveyor system conveys to the assembly station a plurality of core veneers 128 and of` back and center veneers 130~
Conveyor sy~-tem 126 conveys to the assembly station a plurality of ~ace veneers 132, As they travel along the conveyor system including conveyor units 120J 122, 124 the core veneers and back and center veneers ara preheated with suitable heating units 13l~. Preferably, the heat~n~ units comprise -in~rared heatin~ units capable of heating the veneers to a temperature of from 200 to 400 F. during their time o~ passa~e throu~h the heatin~ unit. Singly, the veneers may be heated to this temperature rapidly even though wood is a poor . .
, ~S5~3;~
concluctor o~ heat. The contrary is true ir it is attempted to heat the veneers in a stack during hot pressing.
As they tra~lel along con-veyor system 1267 face veneers 132 are preheated to thc same temperature level by means of heating elements 136.
Foamed ~lue is applied to core veneers 128 and back and center veneers 130. The application is made to the upper sur~ace only of ; these veneers. It is made by means Or an extruder head such as heads 70, 70a, or 70b of Figs. 2, 10 and 13, respectively. This head applies to the veneers a coatin~ of foamed ~lue 140 in a pat-tern determined by the size and dimensions Or the exkruding orifices. -No adhesive whatsoev~r is applied to the surfaces of face ven-eers 132.
~ t the ~ssembly station, the core, back, center and face ven-eers are co~osLted int;o a plywood fls~embly lL~2. This i'3 combined with other panel assemblies to form a press load which ;.9 trans-ferred into a press 144 and consolidated into plywood panels.
The press may be either a sin~le opening or multiple openlng hotpress, or a cold press. It is a feature of the ~nvention that by 20 preheating the veneers, it is possible to use a high capacity sin-gle opening cold press at a press time Or under 2 1/2 minutes and still bond the veneers efficiently into the finished panel.
Durin~ pressin~, under conventional plywood press conditions, the foamed condition of the glue changes, The foam breaks because of two factors which inherently are present in a plywood press.
The first of these is pressure, which breaks the component bubbles of the foam. The second is the mi~ration of the water out of the aqueous foamed glue into the porous wood of the veneers, particu-larly under the influence of heat. ~his necessarily destroys the foam. Glue lines then are formed between the veneers which set to unite them~
The method above described has several significant advantaEes, .
. .
-16- ~-. , , : , . , ~ . ~ .
l~SS1~32 ~ irst, a~ noted, since the v~nears are prehflated, press times are markedly reduced and plant capacity corre~pondin~l;ly increased.
Second, since the amount of glue applied to the veneers i9 independent of the veneer thickness, it may be predetermined acc-urately without the necessity of over application to insure an adequate bond.
Third, since the ~lue may be placed ~ccurately on the veneer surface, lt need not be spread over trim areas. This effectuates further savin~ of elue.
Fourth, since the foamed ~lue occupies a relatively lar~e volume, and since it isapplied in the for~ of filaments or rods having but a limited contact with the hot veneer surface, problems of ~lue dryout are minimized with con(omitant improvement in bond.
Fi~h, since but a very short time interval elapses between the intro~uction of the ~lue into the system and the pressin~ of the panels ln the pre3s, hl~hly reactive ingredients rnay be intro-duced directly lnto the ~lue Just before it enters the foamer.
Such an ingredient comprises for example a catalyst added to a thermosettin~ resin glue, or formaldehyde added to a blood glue.
Sixth, sinc~ the foamed glue may be applied in the form of di~crete, laterally spaced filaments or rods, multiple extrusion heads may be employed to apply filaments alternately comprising substances which when mixed react chemically with e~ch other. The mixin~ and reaction then will occur during the press cycle at which time the filaments will be flattened into contact with each other durin~ the co~pression and breaking of the foam to form the plywood glue lines.
This concept may be extended to situations wherein the ensuin~
reaction is exothermic. Where the reactants comprise a thermo-setting resin glue and a catalyst -thereforJ the two may be applied separately, intermingled in the press, with the ensuing reaction liberatin~ sufficient heat to set the glue. This may be accomplished ~05SI!33Z
without the application of heat from an ex-ternal sourc0 so that, for the first ti~e, hot press glues may be used in the manufacture of plywood without -the use of a hot press.
An example i9 a thermosettin~ re~inous condensation product of resorcinol and ~ormaldehyde used with a para~ormaldehyde catalyst therefor. Another example is a thermosettin~ resinous condensa- ~;
tion product of phenol and formaldehyde as one componentJ a thermo-~ettin~ resinous condensation product of acetone and fo~aldehyde as a second component, and a catalyst therefor as a third co~ponent.
'.0 Seventh, by the use of foamed ~lue as opposed to liquid glues it is possible to apply the glue by means of extrusion. Extrusion procedures are not easily applicable to liquid glues since the solid fillers and debris which the glues invariably contain tend to plu~ the small openin~s throu~h which the liquid ~lues necessarily must be extruded, By foaming the glue and hence by increasin~ ;
Its volume five-~old lt ls possible to employ extrus;on heads having apertures sufficiently larce to avoid this problem.
Eighth it is possible to control easily and accurately the amount of ~lue applied to the veneers. This may be accomplished in ;
20 a major degree by altering the speed o~ pump 18, or by alterin~ ! ' the speed of the conveyor systems conveying the veneers, or by ch-angin~ extrusion heads 70, or by a combination o~ these expedients Minor variations in spread may be obtained by taking advantage of the fact that the extruded ~llaments are stretchable. Because of this a surprisin~ly wide ran~e o~ spread rates can be had with a given extrusion aperture~ Within limits varying the rate of glue extrusion relative to the speed of veneer conveying merely causes the applied glue filaments to stretch slightly or condense slightly without breaking. The necessary co~trol for optimum ~lue utiliza-tion thus is achieved accurately and easily.
- A
Claims (27)
1. The method of making a laminar product which comprises a) continuously propelling in unfoamed condition and at a pre-determined flow rate, a liquid comprising a liquid glue or liquid glue component, b) continuously foaming the liquid as it is propelled, c) continuously extruding the foamed liquid on the surface of a first sheet at a predetermined flow rate of foamed liquid and predetermined rate of traversal of extruded foamed liquid and surface relative to each other, d) applying a second sheet to the foamed liquid on said surface, e) at least one of said sheets being a porous cellulosic sheet, and f) pressing the resulting assembly under conditions predetermined to break the foam and create a substantially unfoamed glue bond uniting the sheets.
2. The method of claim 1 wherein the flow rates of the unfoamed and foamed liquid are maintained substantially the same, on a unit weight of liquid per unit time basis.
3. The method of claim 2 wherein the foamed liquid is extruded and deposited on the surface in laterally spaced filaments.
4. The method of claim 2 wherein the foamed liquid is extruded and deposited on the surface in laterally spaced filaments, the filaments being stretchable and extruded by passing the filaments and the surface relative to each other at a relative rate such that the filaments are stretched as they are deposited in frictional en-gagement with the surface to an extent determining the magnitude of application of the liquid.
5. The method of claim 2 wherein the foamed liquid is applied to the surface by extruding it thereon in the condition of a substan-tially continuous film.
6. The method of claim 2 wherein the liquid is foamed by feeding a foam-promoting gas into the liquid as it is propelled, and then mechanically agitating the resultant mixture of gas and liquid.
7. The method of claim 2 wherein the liquid is foamed by feeding a foam-promoting gas into the liquid as it is propelled and then mechanically agitating the resultant mixture of gas and liquid, by passing the mixture between a recessed rotor and stator in the direction of the axis of rotation of the rotor.
8. The method of claim 2 including the step of adding to the un-foamed liquid a material chemically reactive toward the liquid and thereafter immediately foaming the liquid and applying the foamed liquid to the surface in the time interval elapsing between the time of addition of the reactive material and the time required for substantial reaction with the liquid to occur.
9. The method of making plywood which comprises:
a) continuously propelling an unfoamed liquid plywood glue at a predetermined flow rate, b) continuously foaming the liquid glue as it is propelled, c) continuously applying the foamed glue to the surfaces of a succession of wood veneers, d) laying up the veneers into a plywood assembly, e) and pressing the assembly to form a plywood panel, thereby breaking the foam and forming substantially unfoamed glue bonds between the veneers.
a) continuously propelling an unfoamed liquid plywood glue at a predetermined flow rate, b) continuously foaming the liquid glue as it is propelled, c) continuously applying the foamed glue to the surfaces of a succession of wood veneers, d) laying up the veneers into a plywood assembly, e) and pressing the assembly to form a plywood panel, thereby breaking the foam and forming substantially unfoamed glue bonds between the veneers.
10. The method of claim 9 wherein the foamed glue is applied to the veneer surfaces by extruding it thereon in the form of laterally spaced filaments.
11. The method of claim 9 including the step of preheating the ven-eers preliminary to applying the foamed glue.
12. The method of claim 9 wherein the plywood glue comprises a thermosetting resin glue and including the step of pre-heating the veneers preliminary to application of the glue on the surfaces there-of, the amount of preheating being determined to provide the heat required to set the glue during the pressing of the assembly sub-stantially without the addition of supplemental heat from another heat source.
13. The method of claim 9 wherein the foamed glue is applied in the form of laterally spaced filaments, alternate filaments com-prising first and second chemically reactive substances which are caused to mix by the application of pressure occurring during the pressing of the assembly and thence to react chemically with each other to form the glue bond.
14. The method of claim 13 wherein the first and second chemically reactive substances comprise respectively a plywood blood glue and formaldehyde.
15. The method of claim 13 wherein the first and second chemically reactive substances comprise respectively a thermosetting resinous condensation product of a phenol and an aldehyde, and a setting catalyst therefor.
16. The method of claim 13 wherein the first and second chemically reactive substances comprise respectively a thermosetting resorcinol resin and paraformaldehyde.
17. The method of claim 13 wherein the first and second chemically reactive substances comprise respectively a thermosetting resinous condensation product of a phenol and an aldehyde and a thermosetting resinous condensation product of acetone and formaldehyde.
18. The method of claim 9 wherein the foamed glue is extruded onto the veneer surfaces at substantially the same flow rate as the pro-pelled unfoamed liquid glue, on a unit weight of liquid per unit of time basis.
19. In foamed liquid applying apparatus, an extruder comprising:
a) a laterally elongated first chamber, b) means for connecting the first chamber to a source of foamed liquid under pressure, c) a laterally elongated second chamber, having a plurality of extrusion openings along its length, d) conduit means interconnecting the first and second chambers substantially throughout their lengths, and e) valve means disposed in the conduit means for varying the flow of liquid selectively into different lateral portions of the second chamber as required to produce a predetermined flow of liquid through the extrusion openings.
a) a laterally elongated first chamber, b) means for connecting the first chamber to a source of foamed liquid under pressure, c) a laterally elongated second chamber, having a plurality of extrusion openings along its length, d) conduit means interconnecting the first and second chambers substantially throughout their lengths, and e) valve means disposed in the conduit means for varying the flow of liquid selectively into different lateral portions of the second chamber as required to produce a predetermined flow of liquid through the extrusion openings.
20. The apparatus of claim 19 wherein the conduit means is elon-gated laterally, and wherein the valve means comprises adjusting means arranged for adjusting the width of the conduit means in selected locations along its lateral length.
21. The apparatus of claim 19 wherein the conduit means is elon-gated laterally and wherein the valve means comprises a pair of flexible plates spaced from each other and providing an elongated slot therebetween and pressure applying means for applying pres-sure to selected areas of the plates in a direction calculated to flex them relative to each other thereby altering the width of the corresponding portions of the slot.
22. The apparatus of claim 21 wherein the pressure applying means comprises screw means bearing against the plates.
23. The apparatus of claim 19 wherein the conduit means is elon-gated laterally and wherein the valve means includes adjustable sealing means for adjustably sealing off the ends of the conduit means.
24. The apparatus of claim 19 wherein the conduit means is elon-gated laterally and wherein the valve means includes a pair of gate valve members, mounting means slidably mounting the gate valve members one at each end of the conduit means in sealing re-lation thereto, and adjustment means connected to the gate valve members for adjusting their positions as required to seal off predetermined terminal portions of the conduit means.
25. The apparatus of claim 24 wherein the adjustment means com-prises screw means.
26. The apparatus of claim 19 wherein the conduit means comprises a plurality of laterally spaced tubes and wherein the valve means comprises a corresponding plurality of valves one in each tube, for controlling the liquid flow therethrough.
27. The apparatus of claim 19 wherein the conduit means comprises a plurality of laterally spaced tubes and wherein the valve means comprises gate valve means mounted one in each tube.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA225,620A CA1055832A (en) | 1975-04-28 | 1975-04-28 | Plywood manufacture using foamed glues |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA225,620A CA1055832A (en) | 1975-04-28 | 1975-04-28 | Plywood manufacture using foamed glues |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1055832A true CA1055832A (en) | 1979-06-05 |
Family
ID=4102919
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA225,620A Expired CA1055832A (en) | 1975-04-28 | 1975-04-28 | Plywood manufacture using foamed glues |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1055832A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112266724A (en) * | 2020-11-02 | 2021-01-26 | 佛山市协通橡塑制品有限公司 | Coating for wear-resistant layer of running board, preparation method of coating and running board |
-
1975
- 1975-04-28 CA CA225,620A patent/CA1055832A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112266724A (en) * | 2020-11-02 | 2021-01-26 | 佛山市协通橡塑制品有限公司 | Coating for wear-resistant layer of running board, preparation method of coating and running board |
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