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Патент USA US3067826

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Dec. 11, 1962
w~ E_ GOULD
3,067,816
APPARATUS AND PROCESS FOR THE MANUFACTURE OF PAPER
Filed Jan. 20, 1960
36
r._ -
INVENTOR.
Will/‘am E. Gould
H/S ATTORNEY
United States Patent G "ice
3,067,816
Patented Dec. 11, 1952
2
1
generated between covers of these materials and the wire
3,067,816
APPARATUS AND PROCESS FOR THE
MANUFACTURE OF PAPER
William E. Gould, Lewiston, N.Y., assignor to The
Carborundum Company, Niagara Fails, N.Y., a cor
poration of Delaware
screen. They pick up grit and other foreign matter which
Dimensional stability has also
abrades the wire screen.
been a problem. . For example, nylon has a low coefficient
of friction suitable for use as a suction box cover, but it
Filed Jan. 20, 1960, Ser. No. 3,688
8 Claims. (Cl. 162-374)
“grows” or expands due evidently to water absorption.
My invention provides a suction box having a cover
which will permit appreciably longer usage of the wire
the manufacture of paper. More particularly, it relates
other foreign particles which cause abrading action on the
to an improved suction box having a cover in which at
least the outer surface thereof is composed of a dense,
hard ceramic material and a process of making paper
Wire screen. Such covers are dimensionally stable and
the coefiicient of friction between the cover and the wire
screen is low. Furthermore, the useful life of a cover
screens. I have found that suction box covers made of
This invention relates to an apparatus `and process for 10 hard, dense, ceramic materials will not retain grit and
therewith.
'
_
,
ln order to produce paper, economically, high~speed
machines operating at peak eñiciency must be used. The
15 made according to lmy invention is much longer than the
life of the wooden suction box covers now used.
In the drawings, FIGURE 1 is a perspective View illus~
Y trating the general arrangement of a paper~making ma
principal'tonnage of paper produced is processed on Four
chine in which my suction box cover may be used;
drinier machines. At the beginning of the century, the
FIGURE 2 is a plan view of a suction box having a
maximum speed at which these machines operated was 20
cover made according to my invention attached thereto;
in the neighborhood of 500 feet per minute. Today,
speeds as high as 2,000 feet per minute are common.
FIGURE 3 is a section taken on line III-III of FIG
These increased speeds have substantially decreased the i URE 2; and
FIGURE 4 is a sectional view of an alternative form
cost of producing paper. Yet, full advantage of this
potential has not been possible since the useful life of 25 of cover made according to my invention.
Referring to FIGURE l, a slurry 10 of wood pulp and
parts of the machines is materially limited by use at
such high speeds.
Water is fed from a flow box 11 onto a rapidly moving,
endless wire screen 12. The screen passes around end
In a Fourdrinier machine, a slurry of wood pulp and
rolls 13, at least one of which is driven. The slurry, sup
water is fed onto a rapidly moving, endless wire screen.
The slurry deposited on the screen generally contains 30 ported by the wire screen, passes o-ver table rolls 14 and
suction boxes 15. Normal drainage and a vacuum main
less than 1% wood pulp. The screen provides support
tained in the suction boxes draws orf a large portion of the
for the libers While the iibers are matted'and the water
water. The matted tibers are then passed to drying rolls
drained olf. A sidewise shaking motion is imparted to
and sheet rolling equipment, designated generally at 16.
the moving screen to help orient the fibers and give better
felting action. A large portion ofthe Water will normal 35 Suction boxes are composed of a wire-contacting cover
20 and a base member 21. Each suction box is connect
ly drain through the` screen. To increase the speed and
edto a vacuum source by means such as suction lines 22.
efficiency of the drainage, the wire passes over a series
The covers 20 are provided with a plurality of openings
of suction boxes. These are generally made of metal and
or perforations 23 whereby the Vacuum maintained in
have perforated covers whicharein Contact =with- the wire
screen. A vacuum, which i's maintained'in the suction 40 the box- draws -water from -the partially felted fibers.
Generally, each cover is made of a plurality of segments
boxes draws water from the partially felted sheet into the
24, as shown in FIGURE 2.
boxes through the perforations in the cover. The water
Atleast the wire-contacting surfaces of suction box>
which is withdrawn may be recirculated unless too strong
covers made according to my invention are composed of
1y colored.
` `
Suction box covers used today are generally made of 45 a hard, dense ceramic material. I prefer to use an im
end grain maple wood. vAlthough the useful life of the
covers themselves is adequate, they materially limit the
permeable ceramic having a density of approximately 8O
The slurry passing over
. percent or more of its theoretical density and a hardness
of seven or more on Mohs’ scale.
the suction box covers on the wire screen invariably has
Such materials `may be a self-bonded ceramic, such as
useful life of the wire screen.
Some of these particles 50 high-densit , self-bonded silicon carbide. It may be a
ceramic-bonded ceramic, such as silicon nitride-bonded
become embedded in Ithe soft wood cover which results
silicon carbide. Also suitable are the hard, dense, metal
in an abrasive action on the rapidly moving wire screen.
bonded ceramics, such as chromium-bonded alumina, and
The covers wear unevenly which also causes undue wear
hard, dense impregnated ceramics, such as zirconiumV di
on the wire screen.
.
,
At present, the' industry obtainsV in the order of three 55 boride impregnated with molybdenum disilicide. Other
specific hard,v dense ceramics which can be used include
to tive days’ life from wire-screens used on the large,
titanium carbide, boron carbide, tungsten carbide, zir
high-speed machines. Such screens cost between $3,000
conium carbide, titanium boride, zirconium boride, tita
and $5,000 each. In addition to this cost, an extra shift
nium nitride, zirconia, alumina, nitride-bonded silicon
of men is frequently required to change the screen and,
of course, use of the machine must be discontinued. The 60 carbide, metal-bonded titanium carbide, and metal-bond
ed tungsten carbide.
substantial savings involved in anyincrease of the useful
The manufacture of hard, dense ceramics is known to
life of a wire screen is readily apparent. Even if the use
particles of grit and dirt therein.
the art. For example, Schildhauer et al. U.S. Patent No.
2,907,972 discloses the manufacture of dense silicon car-.
the savings would be very substantial. Not only would
the number of screens used be reduced, but also the 65 bide. The preparation of chromium-bonded alumina is
disclosed in Conant et al. U.S. Patent No. 2,698,990.
screen changes could be made on the weekend, thereby
ful life of a wire screen could be increased to six days,
The suction box cover may be formed with the openings
or perforations 23 therein by standard ceramic forming
Several alternatives to the normal end grain maple box
techniques. The dynamic bearing surfaces should be
covers have been tested. Various plastics, rubbers and
leather have proved unsuccessful or not fully satisfactory. 70 smooth and are, therefore diamond ground, if necessary.
As shown in FIGURE 3, suction box covers may be
In general, covers made of these materials have been too
made entirely of the hard, dense ceramic material or,
soft, wearing the wire rapidly due to the high -friction
eliminating shutdowns during the working week.
3,067,816
3
as shown in FIGURE 4, a wire-contacting ceramic section
30 may be bonded to a base plate 31. Also, a layer of
hard, dense ceramic could be coated or sprayed on a base
plate. Any common material such as steel may be used
for the base plate. Preferably, it should be capable of re
ceiving screws or other fastening means directly from the
base of the box. Epoxy resins will form a good bond be
tween the ceramic section and the base plate. If a solid
ceramic cover is used, clamping means, such as shown
in FIGURE 3, are preferable to direct connection between
the box base 21 and the cover 20. I have shown a fixed
clamp 3S fastened to one side of the box base and a
movable clamp 36 mounted on the opposed side of the
box base.
While the initial cost of suction boxes made according
to my invention is greater than that of suction boxes
4. In paper-makingrmachinesin which a moving wire
screen member passes over and contacts a suction box, an
improved suction box comprising: a base member and a
cover, said cover comprising a plurality of perforated,
wire-contacting segments each having a dense, hard,
wear-resistant surface that will not retain grit and other
foreign particles which cause abrading action on said
screen and said wire-contacting segments consisting es
sentially of an impermeable ceramic material having a
hardness of at least 7 on Moh’s scale.
5. A suction box cover for a paper-making machine
including a moving wire screen, said cover comprising a
screen contacting surface portion that is dense, hard, and
wear-resistant and that will not retain grit and other
foreign particles which cause abrading action on said
that the cost of operating a machine having my suction
boxes will he substantially less than one using boxes hav
screen, said surface portion being composed of an imper~
meable ceramicY material of the character of self-bonded
silicon carbide, and having a density of at least 80 percent
of its theoretical density and a hardness of at least 7
ing the common wood covers.
on Moh’s scale.
with maple covers presently used, it is readily apparent
In a test on an operating
Fourdrinier iachine, one segment in each of eight suc
tion box covers was made of hard, dense, self-bonded
6. In paper-making machines in which a moving wire
screen member passes over and contacts a suction box,
silicon carbide. The remaining segments were end grain
an improved suction box comprising: a base member and
maple.
The sections of the wire screens which contacted
a cover, said cover contacting the moving wire screen
only the ceramic segments showed approximately 30 to
and having a dense, hard, wear-resistant, wire contacting
surface that will not retain grit and other foreign particles
40 percent less wear than the sections of the same wire
screens which contacted the end grain maple segments.
Furthermore, after three-months’ operation, the ceramic
segments showed practically no wear, whereas the maple
which cause abrading action on said screen, said cover
being composed of self-bonded silicon carbide, and having
a density of at least 80 percent of its theoretical density
segments showed extensive wear. Thus, it is apparent that 30 and a hardness of at least 7 on Moh’s scale.
7. In paper-making machines in which a moving wire
by use of my invention, the useful lives of 4wire screens
and suction box covers are substantially increased. Main
tenance costs are materially reduced and the power re
quired to operate the machine is likewise reduced.
While I have described the present preferred embodi
ments of my invention, it is to be understood that it may
be otherwise embodied within the scope of the following
claims.
screen member passes over and contacts a suction box, an
improved suction box comprising: a base member and a
cover, said cover comprising a base plate and a wire
contacting section bonded to said base plate, said section
having a wire-contacting surface that is dense, hard, and
wear-resistant and that will not retain grit and other
foreign particles which cause abrading action on said
screen and said Wire-contacting section being composed
of self-bonded silicon carbide, and having a density of
I claim:
l. A suction box cover for a paper-making machine
including a moving Wire screen, said cover comprising a
at least 80 percent of its theoretical density and a hardness
screen contacting surface portion that is dense, hard, and
of at least 7 on Moh’s scale.
`
wear-resistant and that will not retain grit and other
8. In paper-making machines in which a moving wire
foreign particles which cause abrading action on said
screen member passes over and contacts a suction box,
screen, said surface portion being composed of an im 45 an improved suction box comprising: a base member and
permeable ceramic material having a hardness of at least
a cover, said cover comprising a plurality of perforated,
7 on Moh’s scale.
wire-contacting segments each having a dense, hard, wear
2. In paper-making machines in which a moving wire
resistant surface that will not retain grit and other foreign
particles which cause abrading action on said screen and
an improved suction box comprising: a base member and 50 said ywire-contacting segments consisting essentially of self
a cover, said cover contacting the moving wire screen and
bonded silicon carbide, and having a density of at least 80
having a dense, hard, wear-resistant, wire contacting sur
percent of its theoretical density and a hardness of at least
screen member passes over and contacts a suction box,
face that will not retain grit and other foreign particles
7 on Moh’s scale.
which cause abrading action on said screen, said cover
being composed of an impermeable ceramic material
having a hardness of at least 7 on Moh’s scale.
3. In paper-making machines in which a moving wire
screen »member passes over and contacts a suction box, an
improved suction box comprising: a base member and a
cover, said cover comprising a base plate and a wire 60
contacting section bonded to said base plate, said section
having a wire-contacting surface that is dense, hard, and
wear-resistant and that will not retain grit and other
foreign particles which cause abrading action on said
screen and said wire-contacting section being composed 65
of an impermeable ceramic material having a hardness
of at least 7 on Moh’s scale.
'
References Cited in the ñle of this patent
UNITED STATES PATENTS
128,469
1,644,867
1,703,010
2,215,572
2,602,714
2,637,091
Curtis ________________ -„ Iuly 2,
Berry ________________ __ Oct. 11,
Manson ____________ _- Feb. 19,
Wilson ______________ __ Sept. 24,
Wheildon ____________ __ July 8,
Nicholson ____________ __ May 5,
1872
1927
1929
1940
1952
1953
FOREIGN PATENTS
770,832
Great Britain ________ _.. June 15, 1955
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