Note: Descriptions are shown in the official language in which they were submitted.
2 4 ~
BAC~GROUND OF THE INVENTION
Throughout industry there is of-ten the requiremen-t to effi-
ciently and economically disperse liquids on the surface of particles
which should not undergo mechanical damage or abrasion. Moreover,
many of these particles are collectively crowded together to form a
composite product. The integral strength success of the composite
product, where for example the liquids are binders, is based on the
unirorm or near uniform dispersemen-t of the liquid throughout all the
surface areas of -the par-ticles.
These factors are especially true when wood produc-ts are
being manufactured. However, presen-t methods and available appara-tus
do no-t completely fulfill all of the currently desired economic,
quali-ty and efficiency objec-tives.
For example in respec-t -to the wood wafer board industry
disperse~ment of resin binders is under-taken in blenders, wherein
finely pulverized dry resin is applied to wood wafers via -tumbling
wi-thin an inclined ro-ta-ting drum. The dry resin, so pulverized, is
obtained a-t a higher cost than liquid resins. In -the par-ticle board
industry wood chips are sprayed wi-th liquid resins while -the wood
chips undergo in-tense agitation. The liquid resin is sprayed into the
turbuLen-t mass of wood chips via air atomization or via fluid pressure
nozz:Les. These wood chip blender-s have nozzles which produce droplets
in an unwan-ted wide dispersion of drop:Let sizes. Their air driven
atomization sprays tend -to carry -the finest drople-ts of resin ou-t in
air ven-ting streams, thus creating a nuisance while wasting resin.
Moreover, in these wood chip blenders, -the in-tense agita-tion produces
heat and creates more fine material from -the particles, -tha-t in turn,
-tends -to absorb a dispropor-tiona-te frac-tion of the consumed resin.
In addition, resin-par-ticle agglomerates tend -to build up on -the walls
and paddles of -these blenders requiring frequen-t cos-t:Ly cleaning
~6~24~
main-tenance.
T. M. Maloney in 1977 in a Miller-Freeman publica-tion on
pages 438 through 457 in discussing modern par-ticleboard and dry pro-
cess fiberboard, said labora-tory experimen-tation has shown -that indus-
trial blenders do no-t perform near optimum conditions. Thus important
developments can ye-t be made in -this critical production step.
In respect to information presen-ted in United States patents,
W. Wirz in his Uni-ted S-tates patent No. 4,193,700 of March 18, 1980
disclosed a shor-t leng-th drum wi-th in-ternal vanes or lifters rotated
-to yield an intermittent cascade of particles, while a spray nozzle
dispersed a binder in an axial direction, from the feed end of the
drum into the particle cascade. Also K. Engels in his United S-tates
pa-ten-t No. 4,188,130 of February 12, 1980 illus-tra-ted and described
a drum wi-th in-ternal lif-ters -to ro-tary lif-t partic:les for -their sub-
sequen-t cascading, while a-t -the feed end of -the drum, nozzlex axially
sprayed liquid resin toward -the particles. Although Messrs. Wirz
and Enge:Ls' apparatus compara-tively gen~tly handled the particles, -the
reliance on axially direc-ted sprays required a high drople-t concen-tra-
tion of liquid resin -to achieve a reasonable output rate of treated
particles. Such high concentration of resin drople-ts tends to yield
a wide range in droplet size and reduces the opportunity for uniform
coverage of the par-ticles. Moreover, because one third -to two thirds
of -their in-terior drum surfaces and lifters are also exposed to the
spray of resin, there is the wasteful accumulation of resin on these
exposed in-terior surfaces, also incurring cleaning maintenance cos-ts.
Improved dispersemen-t of liquid resins is also needed in -the
emerging s-tructural board manufac-turing processes, wherein carefully
sliced wood wafers and Flakes are used. To attain maximum panel
strengths of these s-tructural boards the sliced wood wafers and fla]ces
should remain undamaged in blending opera-tions and -thereaf-ter -they
~-- .
should be aligned, as described by ~1. D. Turner in an article
entitled '-Structural Flakeboard Stiffness Rela-tion -to De:Flection
Criteria and Economic Performance', as published in Fores-t Produc-ts
Journal Volume 27, Number 12, December, 1977.
In respect -to all such rela-ted uses of resins, -the distribu-
tion of the resins mus-t be very efficient. Resin, at five percent of
-the dry wood weight, has a resin cost which is about one half of the
wood cost. Usually the resin cost is -the second largest cos-t element
in wood board manufacturing.
Therefore, gentle handling of flakes and maximum efficiency
of -the resin dis-tribution with minimum losses of resin are bo-th
impor-tant objectives in operating wood board processes, and especially
in operating s-truc-tural board processes wherein the wood wafers and
wood flakes are aligned.
SUMMARY OF INVENTION
A new blending me-thod and new blending apparatus are provided
to more efficien-tly utulize liquids such as resin binders and wax
emulsions, par-ticularly in -the wood produc-ts indus-try, by crea-ting
controllable sprays of drople-ts having a high propor-tion of uniform
sized droplets leaving the dges of spinning discs. The particles are
moved via a gen-tle action and in reEerence to wood wafers, wood
flakes, -there is minimal damage or change to these particles. There
are no high speed agitation forces or high pressure agitation forces
involved. Moreover, blender main-tenance is very minimal in respect to
misdirected sprays of liquids and -the accumula-tion of f;nes, both of
which would o-therwise cause plugging or jamming of a blender. This
is true for -the spray is essentially always in-tercep-ted by -the
par-tic'Les, which shield -the in-terior walls of -the blender. By using
the new blending me-thod and apparatus, i-t is es-tima-ted -the liquid
savings, i.e. resin binder savings, e-tc., will range from three
--3--
6-~ 2~
thousand to five thousand dollars a day, at 1980 price levels, during
the operation of a typical three hundred ton capacity plant, i.e. a
wafer board mill.
In respect to the method, the uniform and economical disperse-
ment of the liquids, via sprays of droplets, on surfaces of particles
is undertaken by moving the par-ticles via rotary lifting, followed
by their free falling, with a spray of droplets originating from
a central area of the overall mo-tion path of the partlcles.
In a preferred embodimen-t of the blending appara-tus, a hollow
drum is rotated about a near horizontal axis. Inside the drum,
moun-ted on a common rotating shaft, are spaced slightly conical
discs, which ul-tima-tely disperse respec-tive sprays of drople-ts from
a cen-tral area. This cen-tral area is de-termined or defined by -the
par-ticles being lif~ted, while centrifugally held to the interior of
the drum and then at the zenith locale near -the top of the drum
in-terior, -the gravitational force becomes effective enough so the
par-ticles drop in an arcuate ¢ascade path back down to the interior
surface of the drum -to star-t another cycle. These cycles of lifting
and cascading are predetermined in number to con-tinue until the
particles acquire -the selective and sufficient quan-tity of dispersed
droplets on all -their surfaces. Then the -trea-ted particles leave
-the in-terior of the rota-ting hollow drum a-t -the exi-t end, opposi-te
-the end of -their en-try in-to -the drum. This me-thod and appara-tus is
par-ticularly useful in -treating, wi-th liquid binders and/or wax
emulsiQns, -thin wood wafers, wood flakes, wood shavings, sawdus-t,
ancl o-ther particles of li]ce respec-tive sizes, which often are subse~
quen-tly collec-tively :Eormed and pressed in-to produc-ts such as wood
~afer boards and s-truc-tural boards.
ESCRIPTION OF _ ~WINGS
~ preferred embodiment and o-ther embodiments of the blending
_ L~ _
L 2 ~ ~
appar-atus are illustrated in the drawings supplemented by illus-tra-
tive manufac-turing facility schematic flow charts, and graphs concern-
ing the working r-ange of droplet size and travel, wherein:
Figure 1 is a schematic flow char-t of a composite wood pro-
duct manufacturing facility indicating where the blending apparatus
and method are utilized with respect to -the order of the overall.
apparatus and method;
Figure 2 is a graph illustrating the desirable working range
in respec-t to -the size and travel of the droplets of -the l.i~uids, such
as resin binders and wax emulsions;
Figures 3 and 4 are cross sectional views illustrating the
me-thod and apparatus with respect to the ro-tary lifting of the
par-ticles, followed by their free falling in an arcuate cascade, with
a spray of drople-ts originating from a cen-tral area of -the overall
motion pa-th of the particles, also showing differen-t interior surface
configurations o:F -the drums;
Figure 5 is an isome-tric view of a pre:Ferred embodimen-t of
-the b:Lending apparatus, i.e. the blender, wi-th por-tions removed for
i]lustrating the interior of the drum, and the arrangemen-t on the
shaf-t and the multiple discs;
Figure 6 is a side view of another embodiment of the blender
illus-trating a -tapered drum and also showing -the entry and exit for
-the par-ticles;
Figure 7 i.s a side view of another embodimen-t of the blender
illus-trating a three section drum, with each sec-tion being of a
differen-t diameter and having a respec-tive drive assembly opera-ting
a-t a differen-t ro-tating speed, and also showing the entry and exi-t for
-the par-ticles;
Figure 8 is a pa:r-tial. longi-tudinal cross sec-tional view
-taken near -the en-try end of -the blender showing -the long ro-ta-ting
--5--
~ 3 ~
shaft that carries spray discs illustrating the supply and s-tarting
distribu-tion o:F both a resin binder and a wax emulsion;
Figure 9 is a par-tial -transverse cross sectional view show-
ing the starting dis-tribu-tion of -the wax emulsion, with this view
being taken along line 9-9 of Figure 8;
Figure 10 is a partial -transverse cross sec-tional view
showing the starting distribution of the resin binder, with this view
being taken along line 10-10 of Figure 8;
Figure 11 is a partial transverse cross sectional view show-
ing -the s-tarting distribution of both the resin binder and wax emulsion
wi-th -this view being -taken along line 11-11 of Figure 8; and
Figure 12 is a partial longitudinal cross sectional view
illus-tra-ting how a liquid, either the wax emulsion or -the resin
binder, is dis-tributed -to -the ou-ter periphery, i.e. the rim, of -the
rotating, sligh-tly conical, disc, for depar-ture in a spray of droplets
enrou-te to dispersion on -the su-rfaces of -the particles.
DESCRIPTION OF THE INVENTION
-
One Environmen-t oE Where the Blending Me-thod and Blender are Utilized
The preferred embodiment o~ -this inven-tion is described in
reference -to its u~tilization in a manufacturing process wherein wood
par-ticles are formed and pressed in-to wood products. In Figure 1
the overall me-thod s-teps and rela-ted apparatus of such a manufac-turing
process are illustrated in char-t form. Logs are debarked and cut to
length 10; ho-t soaked 11; flakes or other particles are made 12; they
are dried 14; and as necessary the dried flakes are s-tored in a bunker
16, for subsequent processing. These inven-tions, i.e. both a blending
me-thod and a blender 18, are used in the nex-t step of -the overall
process, wherein -the par-ticles are efficien-tly, economically, and
uni~orm:ly -treated in -the b:Lender being sprayed wi-th drople-ts of resin
binder and/or wax emulsions. The -trea-tecl par-tic:les are, if necessary,
--6--
2 4 ~
s-tored in a bunker 20; then formed 22 in ma-t; ho-t pressed 24, adjusted
for moisture content in a humidifier 26; trimmed by saws 28; stored,
as necessary in a warehouse 30; and shipped 32 upon an order of a
customer.
Preferred Liquid Drople-ts Sizes and Their Travel in Reference to
Their Creation and to Their Dispersion, Reference to a Disc Spraying
Theory
In the practice of this method and the ar-rangemen-t and opera-
tion of the apparatus, -the crea-tion of the liquid droplets in all
r-espects, and especially in reference to their si~es and travel, is
very important. Also, as discussed subsequently, the movemen-t of the
particles to receive the dispersed droplets is likewise very impor-tant.
In reference to a disc spraying theory, -the production of
sprays and mis-ts by means of spinning discs, is believed to have been
first investigated experimen-tally and -theore-tically by Messrs. Walton
and Prewet-t and later in more de-tail by Mr. Drummond. These earlier
experimen-ts may have per-tained -to spinning discs used commercially to
spray insecticides and paints; however -the observa-tions are deemed
pertinent to understanding why and how rotating, i.e., spinning, discs
are used in -the method and blender of this inven-tion.
The forma-tion of drops leaving from the edge of a spinning
dics is analogous in many ways to drop forma-tion leaving from a sta-
tionary -tip. Liquid flows -to the edge of -the disc and accumula-tes
until the centrifugal force on the collected mass is greater -than the
re-taining forces due to surface tension, and then -the drop is thrown
off. Thus, it is reasonable -to expect -the produc-t of the surface
tension and linear dimension of the drop to -the propor-tional -to -the
cen-trifugal force.
In symbols: (~d3 p ) ( w2 D ~ ~ Td or rearranging
( 6 ) ( 2
1/2
~ ~ 6~245
dw (TP) = constant
where d = drop diame-ter T - liquid surface tension
p = liquid specific D = disc diameter
gravity
w = disc angular velocity
Extensive experiments by Messrs. Wal-ton and Prewett resulted
in an average value for the constant of 3.8, wi-th a range of 2.67 to
6.55. Their experimen-ts also showed, the sharpness or edge profile
of the disc was of minor importance. In the range of viscosity
investigated, 0.01 to 15 poise, viscosi-ty had lit-tle effect on tne
spraying process, although high viscosi-ty did tend to reduce the
maximum flow ra-te a-t which homoegenous drops are formed. At small
drop sizes, the drops or drople-ts become airborne, forming a mis-t.
Mr. Drummond presented his experimental resul-ts showing the
effec-ts of flow ra-te Q, kinema-tic viscosi-ty u, and spin rate w, on the
drop size d and ra-te of drop produc-tion. Drop volume is shown to
exceed the volume predic-ted by Messrs. Wal-ton and Prewe-tt's sta-tic
model, indica-ting that -the dynamics of drop forma-tion mus-t be included
in the model.
In -the course of perfecting this invention a number of exper-
iments were conducted in which a paper -tape was exposed to the spray
pa-t-tern for a short in-terval, thus recording -the droplet size distri-
bu-tion and spray pattern. Bo-th water and high viscosity liquid phenol
formaldehyde resin were used. U-tilizing equation, and -the following
parame-ters: D = 250 mm, w = 53L~ radians/second, T = 7.3 dyne/mm, and
p = 1.1, -the theore-tical drop size was predicted a-t 0.12 mm as compared
-to experimen-tal values of 0.20 to 0.30 mm. This agreement was con-
siclered sa-tisfac-tory, and i-t was no-ted -the drops inevi-tably -tend to
spread ou-t, ra-ther than retain -their spherical shape upon reaching a
surface of a par-ticle -to be -trea-ted.
--8--
~ 3 6 ~
In Figure 2, the liquid droplet size and travel are illus-tra-
ted in a graph to indicate the working range selected in reference -to
the method and operation of the blender of this inven-tion. The drople-t
size graph line has a y ordina-te regarding size expressed in microns
and an x ordina-te regarding centrifugal force expressed in multiples
of the gravitational force. The drople-t size graph line has a y
ordinate regarding dis-tance to -travel in centimeters and an x ordinate
regarding centrifugal force expressed in multiples of the gravi-ta-tional
force. The droplet size range is from approximately 200 -to 50 microns
and the droplet travel range is from about 90 cm to 20 cm depending
on liquid proper-ties and gravi-ty force multiples at the spray disc rim.
Thus, volume per drop may range from 4200 x 103 cubic microns to 65 x
103 cubic microns, i.e. a 64 fold range in drop size.
The Con-trolled Movemen-t of Particles as They are Being Trea-ted wi-th
-the Sprayed Liquids, Commencing with Ro-tary Lifting and Then at a
Zeni-th Locale Free Falling at an Arcuate Cascade, Wi-th the Spray
Coming from Spinning Discs Located on -the Central Area Defined by
the Overall Movement Path of -the Particles
In Figures 3 and 4, -the contr-olled movemen-t of par-ticles 13
is illustra-ted as viewed in a -transverse sec-tion -taken -through a
rotating drum 17 of a blender 18. The drum 17 rotates in a clockwise
rotational direction on bearings 15 mounted on an adjus-table frame 19,
shown in par-t. In a central area 21 or volume of the interior of the
drum 17 -there are spaced ro-tating, i.e. spinning, discs 52 which create
the spray of drople-ts of liquids such as resin binders or wax emulsions.
The interior walls 23 of -the drum 17 are coated with a plas-tic finish so
-the par-ticles 13 will not adhere to -these in-terior wall surfaces. Also
even-tually when cleaning becomes necessary, the plastic covered walls
are readily cleaned. Thereforel as viewed in Figures 3 and ~, longi-
-tudinal ribs 25 or raised portions 27, i.e. lands and grooves are
u-tilized in assis-ting iTI -the ro-tary lif-ting of -the par-ticles 13 -to
compensa-te when necessary for -the effec-ts of -the plas-tic finish. They
_ g_
insure -the radial in-termixing of the par-ticles as -they traverse the
blender.
As illustrated in bo-th Figures 3 and 4, the particles 13 are
rotary lifted while positioned adjacent -to the interior wall 23 of the
drum, un-til gravitational forces become effec-tive in causing the
particles 13 to freely fall in an arcuate cascade un-til reaching again
the interior wall 23 to begin ano-ther cycle. Each respec-tive spinning
disc is located, in reference to a par-ticular -transverse cross sectional
view, within -the central area defined by the overall movement of the
collective particles 13. As observed in Figures 3 and ~ the sprayed
droplets 29 reach the particles without any appreciable amount of them
escaping on through to unwantedly contact the in-terior wall 23 of the
blender 18.
The Addi-tional Controlled Movemen-t of -the Par-ticles Under Trea-tment
to Move them on Through the Blender While Being Sprayed wi-th Liquids
and Reference to Speed Changes at -the Circumference of the Interior
of the Drum
In Figures 5, 6, and 7, -the longi-tudinal observations indi-
ca-te -the drum 17 of -the blender 18, in various embod;men-ts, always
ro-tates abou-t a near horizon-tal axis, with the entry end receiving -the
particles 13 being higher than the exit end discharging the particles
13. The reten-tion -time of the par-ticles 13 in -the blender 18 is con-
-trollable by adjus-ting the angle of inclination of the blender in
respect to its near horizon-tal axis. Generally depending on the
inclina-tion angle the par-ticles make from twenty -to forty revolutions
while being -treated in the blender 18. For example in a ten foot
diame-ter blender twen-ty fee-t long a one minu-te re-ten-tion time, when
-the drum 17 is ro-ta-ting at twenty five revolu-tions per minute, requires
an inclina-tion angle of about four and one half degrees.
In reference -to -the ro-ta-tional speed of -the drum 17 of a
blender 18, under some circumstances, as wood wafers, for example,
--10 -
~ 3 ~4~
acquired resin binder on -their surfaces the drum speed preferably has
to be gradually decreased -to achieve -the most desirable cascading free
falling ac-tion of the particles 13. Therefore, in reference to -the
entire length of a drum 7, and realizing as the particles progress
from the en-try -to the exit they gain in their receipt of resin binder,
-the peripheral or circumferential speed is automatically reduced by
utilizing a -tapered drum 33 as illustrated in Figure 6. Or a sectional
drum 34 is used as shown in Figure 7 for a mu1ti-stage operation wi-th
the telescoping sections 35, 36, 37 being opera-ted at different
rotational speeds so their respec-tive peripheral or circumferential
speeds may be reduced as necessary.
The Arrangement of the Componen-ts of the Blender as Illus-trated in
E'igure 5
The blender 18 illus-tra-ted in Figure 5, has a drum 17 of
constant outside diameter. As necessary -the in-terior diame-ter changed
by -the addi-tion of prperly sized liners, not shown, to accommodate
-the possible need for a reduc-tion in the peripheral speed, i.e. speed
a-t -the circumference of -the in-terior. The overall suppor-ting frame
19 is adjustable to change the retention time of -the particles 13
within the drum 17. A-t the exit end -there is a pivota] frame mounting
38 and at the forward end there is a level changing frame mounting 39.
Such angular adjus-tment of frame lg likewise adjus-ts the en-tire compo-
nents of the blender 18 through -the small angle of inclina-tion.
A motor 40, via a power transmission bel-t ro-tates ahft 42.
Spray discs 52, 53, 54, 55, 56 and 57 are mounted a-t spaced intervals
a]ong large diame-ter -tubular shaf-t 42 and their spinning speed is
controlled by opera-ting mo-tor 40.
An adjus-table speed mo-tor 43, via a power -transmission bel-t
of change 44, drives a line shaft 45 moun-ted on bearings 46 secured
-to :Frame 19. Near -the ends of shaf-t 45 are fric-tiona:L drive wheels
47 which ro-tate within circumferen-tial track channels or rails 48
secured around -the drum 17, thereby rotating the drum 17 in a clock-
wise direction, as indicated by the motion arrow in Figure 5.
The Arrangement of -the Components of the Blender as Illustrated in
Figure 6, and the Entry and Exi-t of -the Par-ticles
The blender 18 illus-tra-ted in Figure 6, has a tapered drum
33 which serves to automa-tically reduce the peripheral speed, i.e.
speed at the circumference of the in-terior, -to compensa-te for -the
particles nearing the exit which have changed in dynamic behavior in
respect to their adhering resin binder droplets 29. The angular
adjustments of the horizontal inclination of the drum 33 are similar
to those indica-ted in Figure 5. Also the power transmissions respec-
tively -to both the shaft 42 and the tapered drum 33 are similar to
-those described in regard -to -the blender 17 shown in Figure 5. As is
also true~ bu-t not shown in Figure 5, the particles 13 are illustrated
in Figure 6, being delivered via a loading conveyor 49 and direc-ted
into a loading chute 50 secured to -the non-rota-ting entry end enclo-
sure 51. After passage through -their various advancing cycles within
-the drum 17, -the particles :L3 with -their accumulated resin binder
leave the drum 33 via the exi-t chute 58 positioned by the non-rotating
exit end enclosure 59 and then they drop onto the discharge conveyor
60.
The Arrangement of the Components of the Blender as Illus-trated in
Figure 7 and the Entry and Exit of -the Particles
The blender 18 is illustrated in Figure 7, has a sectional
drum 34 having three sections 35, 36, and 37 increasing in diameter
and -telescoping. Many of the componen-ts are siMilar to -those illustra-
ted in Figures 5 and 6 and are indicated by like numerals. Each
sec-tion 35, 36 and 37 is driven a-t a different speed so the peripheral
speed, i.e. speed a-t -the circumference of -the respec-tive -three
different diame-ter interiors may be independen-tly con-trolled decreasing
-12-
2 ~ ~
in speed f-rom -the en-try -to -the exi-t of -the sectional drum. This
speed reduction is under-taken -to accommoda-te -the par-ticles receiving
-the resin binde-r which a-t -the slower speed will -then commence -their
free fall in -the cascade a-t -the proper zeni.-th locale on -the respective
in-teriors oF -the drum sections 35, 36 and 37. The power being dis-tri-
bu-ted by the line shaf-t ~5 is dis-tributed via -three -transmission bel-t
or chain assemblies 6:1., 62, 63 -to respec-tive secondary power distri-
bu-tion shaf-ts 64, 65, 66 a-t -the respec-tive drum sec-tions 35, 36 and 37.
The drive whee:Ls ~7 Follow channels or rails ~8.
The Dis-tribu-tion and Supply o:E -the Liquids, For Example, the Resin
Binders and Wax Emulsions, -to -the Spinning or Rotating Discs Which
Crea-te -the Spray of Drople-ts
I:n :Figures 6, 8, 9, 10, 11~ and 12, -the distribution and
supply of -the liquids, i.e. resin binder R and wax emulsion W, to the
spinning discs, such as disc 52, are i.l.lus-tra-ted. ~s shown in Figures
6 and 8, concen-tric s-ta-tionary supply -tubes 67 and 63, respectively
receive -t'he resin binde:r R and the wax emuls.iorl W, received -through
hoses 69 and 70 being fed by pUlllpS 71 and 72 from conve:n-tional supp:Ly
sources of each which are no-t shown. Thereaf-ter -the resin binder R
and the wax emulsion W, af-ter directional changes shown in Figure 8
leave -the s-ta-tionary supply -tubes 67 and 68. These liquids leave
-through downwa:rd poin-ting s-tub ~tubes 73, 7~, which have exit holes 75
direc-ted -to nearby pla-tes 76 and 77 which are :ro-tating rapidly with
-the shaf-t ~i2.
Bearing '78 is used in posi-tioning -the stationary supply
-tubes 67 and 68 rela-tive -to -these por-tions, inclusive of pla-tes 76 and
77, which are ro-ta-ting wi-th -the sha:F-t ~2. Bearing 79 is used -to posi-
-tion the :ro-ta-t:ing s'ha~-t re:La-ti,ve -to ~the frame 19 of -the blender 13.
The resin binder R and the wax emulsion W, respec-tively upon
3n :Leaving exi,-t holes 75 t:ravel throug}l space un-til. reachi:ng pla-tes 76
al-ld 7'7. T~le:reclf-ter cerxtr:i.:Fuga~ or:~ce moves l,he ~I.;quids :radia:l.ly
-13-
outwardly -to -the inner wall 80 of a cylindrical sec-tion 81. Pla-te 82,
installed with the aid of grooves 108 and sealing rings 109 similarly
-to the ins-tallation of pla-te 76 serves -to keep the resin binder R and
wax emulsion W separated -throughou-t -the opera~tions as -these liquids
from the respec-tive rota-ting shallow toroidal pools 83, 84. Continu-
ously during operations, -the liquids depart from -these supply pools
83, 84 and enter respective dis-tribution -tubes 85, 86, 87, 88, 89, and
90, which longitudinally distribute the resin blender R and wax emul-
si.on W to spinning discs 52, 53, and 54 being supplied from -the entry
end of the blender 18. Spinning discs 55, 56 and 57 are supplied in
like manner from the exit end of -the blender 18. These dis-tribu-tion
-tubes are located within the protec-tive longitudinal cylindrical shaft
91 secured by fas-teners 93, af-ter being posi-tioned in plate 92 which
also seals off the liquids :F:rom -the interiors of the shaft associated
componen-ts such as tubular shaft 91. The cross sec-tional views of
Figures 9, 10 and 11 Fur-ther illustrate -the dis-tribution of liquids R
and W.
In Figure 1.2 distribution of liquid resin binder ~ to a
spinning disc 53 is shown. This liquid is directed through conduits
85 and 89~ then caused -to change direc-tion into stub tubes 94, 95 and
discharged in-to a first shallow -toroidal supply pool 96. Af-ter reach-
ing a pre-se-t level, -the liquid is longitudinally drained in-to a larger
shallow toroidal pool 97 via a series of annular holes 98 in a dividing
par-tial bulkhead, flange, or annular orifice :ring 99. Thereafte:r in
an adher-ing ou-twardly flow path 100~ -the liquid moves -to -the rim 101
of -the spinning disc 52. The flow of liquid in pa-th 1.00 uni.formly
ex-tends -throughou-t the circular conical surface area of -the disc 52 -to
even-tuall.y con-tinuous:Ly depar-t in a spray o:F drople-ts 29. The peri-
me-ter speed o:F disc 52 is abou-t four-teen -thousand Eee-t a minu-te for a
disc 20 inches in diame-ter~ Circu:lar- pla-te :L03 secured by fas-teners
~ 3 ~3~ 2~ 5
104 shields the f]ow path 100 of liquid from wind and dust. Fasteners
105 secure the disc assembly 106 to the tubular shaf-t 91. Fas~teners
107 secure the disc to the disc assembly 106.
Though six spinning discs are illus-trated in Figure 5, i-t is
feasible -to use as few as two or up to -twelve depending on the capa-
city requiremen-ts. The effective spray travel, as indicated in Figure
2 is governed by -the size of the drople-t and disc speed. A-t a cons-tant
G factor, for example, of 2000, the spray -torus diameter is changed
rela-tively little in size, whether the disc is -ten inches or -twenty
inches in diameter.
Information Concerning the Design Considerations in Respect to a
Selected Shaft on Which -the Spinning Discs are Mounted
The natural resonan-t frequency of a long, rotating shaft
de-termines limi-ts on sha:Ft size, speed and span between bearings.
The applicable formula for this embodiment is:
N = 69~ ~ Where: N = natural frequency in
V - 8 circles per second
E = shaE-t modulus o:F elas-tici-ty: for s-teel - 29,000,000 psi
I = moment of inertia of shaft (Inch4)
~0 W = total weight between bearings (Lbs)
L = span between bearings (inches)
For a 12 inch steel shaf-t wi-th a 0.50 wall thickness with a
span of 18 ft. between bearings carrying six twenty inch diameter discs
-the natural frequency speed is about 3,500 RPM. To at-tain 2,000 times
gravi-ty force a-t disc rim requires abou-t 2,650 RPM. This operating
speed provides a wide safety margin below cri-tical resonant speed.
Information Concerning Design Considera-tions in Respect to Drum
Speeds as They eEfect -the Peripheral Speed, i.e. ~the Speed a-t the
Circumference of -the Interior of -the Drum
In pilo-t scale -testing using a 94.5 inch diame-ter drum,
dry wood wafers, i.e. zero percen-t resin binder, had -the op-timum free
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2 ~ ~
falling arcuate cascading action a-t twenty eight and three -tenths
revolutions per minute. This op-timum speed decreased, in an exponen-
tial fashion, to twen-ty six and -thir-ty -three hundredths revolutions
per minute at a six percent resin binder content.
If the ~ree falling arcuate cascading action is not properly
maintained, an unwanted loosely compac-ted layer of wood wafer, i.e.
particles, wi-th their resin binder, may form within the drum. This
layer could periodically disintegrate and cause opera-tional control
problems. However, if the drum is too slow, the wafers start falling
pr-ematurely and may fall directly onto long tubular shaf-t and spinning
discs, thus degrading quali-ty of resin distribu-tion while allowing
resin to reach inner wall of -the drum.
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