US2790413A

US2790413A - Apparatus for continuously applying liquids to the underside of sheet material

Info

Publication number: US2790413A
Application number: US401351A
Authority: US
Inventors: Arthur S Gregory
Original assignee: Weyerhaeuser Timber Co
Current assignee: Weyerhaeuser Timber Co
Priority date: 1953-12-30
Filing date: 1953-12-30
Publication date: 1957-04-30
Anticipated expiration: 1974-04-30

Description

p 30, 1957 A. s. GREGORY 2,790,413

APPARATUS FOR CONTINUOUSLY APPLYING LIQUIDS TO THE UNDERSIDE OF SHEET MATERIAL Filed Dec. 50, 1953 INVENTOR. Ar'lhur S. Grgq-pry United States Patent .ABPARATUSEOR CONTINUOUSLYVAPBEYING -.LIQ S T UNDERSIQEiQFrSHEET MA EBIL Arthur'S.;Gregory, Longviewywash assignor to"Wey,erhaeuser Timber C ompany, ;Taconia,'-Wash -a corporaltion of Washington materials. For example, in the preparationgf hardboard if may b si bl 9 spra the urf ce o a re i d he lh se fibe h a wi a rre term he aua lyi s ta The h h th m th t a s erredte a t. th "was a he de ra le reh at r p a t zi e the fib rs adjacent the surface so that they conform to the contgur 9 t e p es ea l late wi h whi h they are i cnta This imparts a smooth .surface to the finished boa cl. 7 t ih y h .as eri to app a ,1 .5 t ther an ra e? e the eh ae S e .eueh mats- .1 th m nuia tu e pf ha di qa d f ere h l ere may be 1 us i i lied s iieeh e lh ghs su pension sr hiu e e s9: i lhhd r liquid m e ial he s he h es ttins r sinous a h sives, 9r nhr hi s lt used as fir retardant o h. e h sa'h se s ma ria s emplo e .u lhpi'dofing agents." sun further, i may desired .19 a ly to h met h ee e i he' l hel d mate a i abriasi s 9 Ye t su as e h she arhen sol ents, or he lower aliphatic alcohols; or mixtures ,of' liquids in emul- S eh fort e S .SP $ions o s l d in u ds QT melten s lids o thixe pie olloidal syst ms.

ice

. 2 surface, or one which is not uniform in color. Accordingly, it is essential for many purposes-that-the -fibers in the body 0f the-rnat '-be-=notdisturbed and that th-osebn the sur'face 'o'fthe mat be disturbeda-s'littleas possible. -Hence,. inveltting themat is an undesirable procedure, "as is sliding it over a surface once "the-fibers have been moistened, since',-in the latter case; the fibers" tend to stick to the moistened-suiface. i

It now has been discovered that the foregoing difiiculties may be overcome and'even relatively non-coherent sheets sprayedon v their under surfaces with 'liquid i materials by the us-e-of'method 'andapparatus'whi-ch do'not invert-thesheet and whichdonot'moveit relative -to the supporting-surfaceafter it has been moistened, Broadly stated, this method comprise s supporting the sheet Iona first supporting "member moving at a "predetermined velocity and transferring the sheet'to a second (supporting member stationed downstream fromthefirst supporting member and m-ovingin the same direction at the same velocity. At the transfer point between the "two supporting members there exists "a gap at'which an area of the sheet undcrsurface is exposed. Liquid 'thenis 'applied to'the under surface at this transferpoint.

The apparatus for accomplishing the foregoingimethod comprises a member "for supporting the sheet, means for moving it across the supporting member, and conveying means a spaced distance below the supporting member he con i u u app c io of hese and othe l quid sys em to e t sh ee of Sh et esfe t d mats at li noc'el u s fib ual y is e mp shed easily by w l kriewn RrQcedur S, such as r n t ansfer a b l r do s Howe e pp y l qu ds to t it under surfaces as frequently as desirable is impractical or even impossible. of attainment because of several, factors.

If it is attempted to coat the under surface by first; in; vetting the; mat, an additional processing operation; obvi-s Qhsl eq In d eh here a felted fibrous mat is the subject'rnatter of the operation, it is impos ble to invert it without disintegrating it, or disarranging; the fibers of which it is composed.

Such disarrangement of the fibers may-well be fatal to the successful application of the mat in the production of consolidated products. During the preparation of the mat, great care is exercised to distribute the fibers evenly o th t- 5: i l fqh ll thickn ss Als h should be taken to intertwine the fibers and, orient them in random arrangement to obtain a consolidated product of maximum strength. Accordingly, anydisajrran'gement of the fibers, may make the thicknessv of the mat nonuniform so that a board of non-uniform densityeis; ob; tained. Also, it may disentangle thefibers, destroying e fiber interloclg, so that thejco'nsolidated product dela i,- na tes comparatively readily, or is of impaired streng mh h fibers, h, he. m ts P or o Pr. "s ns el e ee h t hah e hseeh ff r nt tpr du iaa rau h the mat; and

and extending outwardly ion the outfeed side of 'the apparatus for conveying th'esheetaway.

' Stationed opposite the space between the supporting member and the conveying means is a liquid applying means for applying liquid .to the exposed under surface of the sheet as it transfers from the support member to the conveying member. At this junction, the liquid may ,be applied uniformly to the under surface without danger of disintegrating the sheet or of disa-rranging the fibers of which it maybe composed.

This apparatus is described in detail below with particular reference to the drawings wherein:

Figure 1 is a schematic view in side elevation of apparatus for forming a mat from fibrous m-ateriaL'including the means described herein for applying liquids to the under surface of the formed mat;

Figure 2 is an enlarged, detail; sectional view illustrating the construction and operation of the herein described apparatus for applying liquid to the underside of Figure 3 is a fragmentary view, partly in section, taken along the line 3-3 of Figure 2. .7

As is illustrated in i the drawings, the apparatus for continuously applying liquids to the underside of moving sheets which comprises the subject matter of the present invention may be employed to advantage in conjunction with apparatus for felting lignocellulose fiber into a mat,

, cutting the mat. into sections, and introducing the secions into a heated press. for consolidating them. Thus in the illustrated embodiment, wood or other fibers may be, introduced into, a foraminous-felting head 10 under a. positive, air pressure. The felting head is provided with a, bladed wheel 12 whichragitates the fibers within the head}, passing themin dispersed form through theop'e'ri ingsrin. thebottom of thehead".

fibers; travel downwardly-into a felting'farea de fined'andpartially enclosed by; shield 14'. I They then are formed, into a, continuous mat on a feltin membersuch as the endlessFourdrinier wire: 16,-at the point where it passes over a suction box 18 maintained under' a1 negatiye air, pressure'rby means; ofifan 20,3 and stationed below audio substantial registration with shield 14.

In this, manner the fibers are sdriven'l-into' auiiiforfii'niat or, sheet 21 onr-the Fourdrinieriwire. i The-mat first passes beneath a press roll 22 which eifects its partial consolidation. It then passes the cut-off saws, represented schematically at 24, which cut it into sections of substantially equal length. 1

The mat sections pass onto a downwardly inclined transfer belt 26 driven in the outfeed direction at a rate, substantially equal to the rate of travel of Fourdrinierwire 16. This transfers the mat sections to a supporting member 28 which preferably comprises :a sheet of metal at least as wide as the mat and inclined downwardly in the outfeed direction at substantiallythe same angle as transfer belt 26. I

Supporting member 28 may be mounted in any suitable manner, but as is illustrated in Figure 2, preferably is rigidly aflixed to an angle iron 30 which extends transversely of the apparatus and is rigid to a pair of vertically disposed, perforated, supporting plates 32, stationedone on each side of the apparatus. Journalled in bearings 34, which are mounted within the perforations in plate 32, is a shaft, 36 supported at each end by a standard 38 connected to the frame of the apparatus. 7 g

Means are provided for precisely adjusting the-angle of pivotally mounted supporting member 28 with respect to the other elements of the apparatus. To this end at least one of plates 32 is provided with a longitudinal extension 39. This serves as a lever arm and has at its outer end a plurality of teeth engaging a worm 40 journalled in bearings 42, 44 which, in turn, are aflixed to standard 38. It will be apparent that by rotating the shaft mounting worm 40, the angle of supporting member 28 may be varied by increments as desired. 7

Cooperating with transfer belt 26 and the pivotally mounted supporting member 28 is means for conveying the mats away therefrom for further processing. In the illustrated form the conveying means comprises an endless belt 50 stationed below Fourdrinier wire 16, transfer belt 26, and supporting member 28. It extends outwardly from the latter and is driven in the outfeed direction at a rate substantially the same as the rate of travel of both the Fourdrinier wire and the transfer belt.

Conveying belt serves a three-fold function. First, as has been noted, it conveys the fibrous mat away from supporting member 28 for further treatment. Secondly, if the subsequent treatment is to be a pressing operation, it affords a means for placing below the mat one of the caul plates indicated at 52,54 and which has dimensions substantially equal to those of the mat. This may be accomplished simply by placing the caul plates edge to edge on the upper end of conveyor belt 50. Then as each mat leaves supporting member 28 it is deposited upon the caul plate directly beneath and in registry with it.

An upper caul plate 56 then may be placed on top of the mat to form an assembly which may be introduced in to a hot press for consolidation into a pressed board product. As is illustrated schematically, such an assembly may. comprise the mat 58, sandwiched between a lower caul plate 60 and an upper caul plate 62, this entire as:

sembly or an assembly including one or more venting screens, being placed between the lower upper platen 66 of a suitable press.

' The third function served by the conveying belt 50 comprises providing an opportunity, in cooperation with platen 64 and the may be used where liquid water is to be applied to the mat; another where an aqueous solution of resin or inorganic salt is to be applied; a third where an organic solution of a solid material is to be applied; and a fourth, where an emulsion or a thixotropic collodial suspension is to be applied.

The illustrated form of liquid applying means is designed particularly for applying water, aqueous solutions, or similar liquids to the mat. It comprises a plurality of spray heads 70, 72 and 74, spaced apart at suitable interyals and supported on a bracket 76. The bracket in turn is slidably mounted on guides 78, 80 so that the entire spray head assembly may be removed conveniently from theapparatus' if'desired. This permits the rapidservicing or adjustment of the spray heads. Each spray head is provided with a mixing chamber 82 which is fed with liquid through line 84 and with air or with other gas under pressure through line 86. 'If desired, the entire spray head assembly may be reciprocated by means of a crank 88. V

t h Operation 7 The operation of the illustrated embodiment. of the present invention is as follows:

Lignocellulose or other fiber is formed into a felt or mat on the forming wire 16 from felting head 10 assisted by suction box 18. The resulting mat then is partially consolidated by roll 22 and cut in sections by cut-off saws 24. These traverse transfer belt 26 and pass over the supporting plate 28, the angle of which is adjustable through worm 40. a As the mat sections travel over the transfer belt and the supporting plate their travel is paralleled by that of

caul plates

52, 54 placed on an outfeed conveyor belt 50 stationed a spaced distance below the transfer belt and the support plate. Accordingly, as each mat section passes over the outfeed end of the supporting plate it is transferred to the caul plate immediately below. Anupper caul plate then may be placed on top of the section and the assembly transferred to the hot press for consolida tion into pressed fiber board.

Liquid is applied by means of spray heads 70, 72, 74 in predetermined quantity and at the selected rate to the under surface of' each mat at the transfer point between support plate 28 and thecaul plate carried by conveyor belt.50. This is accomplished without turning the mat over and consequently without disarranging its component fibers, or disturbing its surface. As a result there are obtained optimum control of the liquid applied; maximum development ofthe desired properties per unit amount of applied liquid; and the production of a consolidated produet having maximum strength, uniform density, and surface characteristics which have been unimpaired by the application of, the liquid. The liquid may beapplied, furthermore, to continuously forming mats or sheets withoutsubstantial modification of the apparatus employed for-their formation and conveyance. Also, if so desired, the upper surface of the mat may be coated with the same or'with a diiferent liquid at any convenient point the supporting plate 28 from which it is spaced apart, for I applying liquid to the underside of the mat efiiciently and without disturbing or disarranging the mat. As is apparent particularly from Figures -2 and 3 this is accomplished by stationing a liquid applying means in this space,

the liquid applying means being directed in the outfeed d rect on so that'it applies liquid to the under surface'of the mat as ittransfers'from supportingmember 28 to conveying'belt 50. A

a The form of the particular liquidapplying means employed is widely variable depending upon such factors as the character of the liquid to be applied, its viscosity, its content of solids, 'etc.. Thus one typeof applying means between the consolidating roller and the point at which the upper caul is placed on the mat.

I It'isto be understood that the form of my invention herewith shown and described is to be taken as a preferred example ofthe same, and that various changes in the shape, size and arrangement of parts may be resorted to without depa' rting from the spirit of my invention or the scope of the subjoined claims.

.. Having thus described my invention, I claim: a

1. Apparatus for continuously applying liquids to the underside of a sheet of felted lignocellulose which comprises a supporting member inclined downwardly in the 'outfeed direction for supporting the sheet, means for moving the sheet across the supporting member at a predetermined rate, conveying means" adapted to carry a'caul plate a spaced distance below the supporting member and extending outwardly on the outfeed side thereof, means connected to the conveying means for driving the same at a rate substantially equal to the rate of travel of the sheet and in the same direction, and liquid applying means stationed between and beneath the supporting member and the conveying means and directed toward the underside of the sheet as it traverses the space between the supporting member and the conveying means and is deposited on the caul plate carried thereby, said liquid applying means comprising at least one sprayhead, a bracket for supporting the sprayhead, means for slidably mounting the bracket on the underside of the supporting member, and means connected to the bracket for reciproeating same laterally with respect to the sheet.

2. Apparatus for continuously applying liquids to the underside of a sheet of felted lignocellulose which comprises a supporting member inclined downwardly in the outfeed direction for supporting the sheet, means for moving the sheet across the supporting member at a predetermined rate, conveying means adapted to carry a caul plate a spaced distance below the supporting member and extending outwardly on the outfeed side thereof, means connected to the conveying means for driving the same at a rate substantially equal to the rate of travel of the sheet and in the same direction, and liquid applying means stationed between and beneath the supporting member and the conveying means and directed toward the underside of the sheet as it traverses the space between the supporting member and the conveying means and is deposited on the caul plate carried thereby, said liquid applying means comprising at least one sprayhead, a bracket mounting the sprayhead, and a pair of spacedapart slides attached transversely to the underside of the supporting member and adapted to slidably receive the bracket therein thereby permitting lateral withdrawal of the bracket from the supporting member.

References Cited in the file of this patent UNITED STATES PATENTS