Improvements in the Process of and Machines for Drying Webs of Cloth, Paper and like Material.
Year: 1898

page_text: Date of Application, 25th Oct., 1898-Accepted, 25th Feb., 1899
COMPLETE SPECIFICATION,
Improvements in the Process of and Machines for Drying Webs
of Cloth, Paper and like Material.
I, HENRY FAIRBANKS, of St. Johnsbury, Vermont, United States of America,
Manufacturer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
This invention relates to a certain new process for drying yarn, warps, cloth
in the web, or paper as it runs from the paper machine, leather board, straw
board and similar products, and to the machine by which this is accomplished,
to wit the vacuum web driver. These webs have heretofore been dried in the
air, by passing them over steam heated cylinders or drying cans, and, since
much heat would injure the fabric, it has been necessary to provide a large
amount of moderately heated surface, making the machines very heavy and very
expensive. Since the webs of cloth are long, and paper runs off from the machine
continuously no way has been previously known of using a vacuum to assist the
evaporation. The new process herein set forth consists in drawing the web con-
tinuously through a heated vacuum chamber, in which the atmospheric pressure
is so far reduced that the water is rapidly vaporized, and actually boiled out at
a temperature so low that the fabric is not injured, the motion and squeezing
of the web contributing to the result. The vacuum must be maintained, suffi-
cient to be effective, and provision must be made for carrying the web into
and out from the chamber without admitting air. It is believed that this pro-
cess has not before been invented.
It
The machine.devised for carrying out this process in the most convenient way
is understood to be a basic invention, and a new article of manufacture.
consists of a closed chamber connected with an exhauster, capable of removing
more than half of the atmospheric pressure; heated preferably to less than one
hundred and ninety degrees Fahrenheit, and provided with roller gates through
which the web to be dried may pass in and out.
The exhauster may be of the ordinary air pump type but, since there is more
steam than water to be removed, a condenser will more than double its effi-
ciency and a comparatively small pump may suffice.
The chamber may be heated by steam coils, but the thin air is a poor conductor
of heat, and for rapid drying, surface contact with moderately hot surfaces may
be necessary, and I use cylinders heated through their axles. The most im-
portant new feature of the drier is the air-tight device through which the web
to be dried is rolled into and out from the vacuum chamber between elastic
faced rolls. Two or more rolls rolling against each other close a rectangular
opening in each end of this chamber, being packed against its walls, forming
roller gates, the elastic surface of one of these closing over the moving web,
and preventing a stream of air from entering with the web. These rolls at the
entrance and exit, and all the moving heated surfaces within the chamber, in
contact with which the web moves forward, are geared together to secure equal

page_text: surface travel for all, and a web of cloth, once started, may require no guiding.
But if a web of delicate paper which has little strength is to be provided for,
it will be necessary to arrange endless carriers. Aprons of wire cloth, duck or
felt may be used, but I prefer endless bands of metallic tape, of which two series
are carried round' in the path by which the web is to move, adapted to receive
this web between them, and guide it through. The tapes of each series are
spaced not far apart, and the two series meet just outside or close within the
roller gates, in position to receive and carry the web.
In the drawings, Figure 1 is a sectional view of one form of the drier look-
ing from the side, showing the chamber, the roller gates at its entrance and
exit, the cylinders with their hollow journals, the carrying aprons or tapes, and
the guide rolls carrying them, and the exhaust pipe. Figure 2 shows the pitch
circles of the gearing by which the several gear wheels engage each other to
give equal surface travel to all the moving surfaces that carry the web. Figure 3
gives an end view of the machine, showing below the condenser and air-pump
connected, and at the right the heater and pump for circulating some liquid
of a predetermined temperature through the cylinders within the machine.
Figure 4 shows a portion of the ends of the cylinders, with the guide rolls and
metallic carrying tapes. Figure 5 gives an enlarged view of the roller gate
packing, stationary guides and last pair of rollers. Figure 6 illustrates the
arrangement when the guide tapes or aprons are made to meet outside the
chamber. Figure 7 shows an alternative form of the drier, in which the web
is carried straight through, while the aprons separate from it, these aprons pass-
ing quite through the chamber and returning outside to receive the web between
them.
B is the closed vacuum chamber, or box, exhausted through the exhaust pipe E,
through the condenser F, by the steam driven air pump L; C, C, C are the
cylinders, heated by steam or hot oil introduced through their hollow jour-
nals S, S¹, S, it being understood that if heated by steam, the usual syphon
arrangement will be used to keep them free from water, and if heated by some
liquid that does not vaporize, the heater H and the pump P will be required.
Around these cylinders are carried two series of metallic tapes G, G₁, running
over loose rollers N, N¹, N", and 0, 0, 0, 0, meeting between 0 and N in
a way to surely receive the web between them and to carry it down under the
cylinder C, then over the cylinder C, and under the third C", in a way to
secure the longest surface contact with their peripheries. The tapes of each
series may be two or three inches apart, or two aprons of wire or cloth may
replace the two series. These tapes are guided by grooves N, 0* respectively
in the rollers N¹, O¹, and O". More cylinders can be introduced in the vacuum
chamber in case it is desired to dry sensitive fibre with less heat, or to run the
web faster, it having been found that six cylinders in such a vacuum as may
be easily maintained will effect as much as forty of the same size and similarly
heated will effect against the pressure of the atmosphere. If a web, such as thin
paper is not strong enough to be managed in any other way, these tapes or aprons
may be arranged to run over the inlet rollers, as illustrated in Figure 6, meet-
ing outside, or be carried quite outside the box as shown in Figure 7, and brought
together as they enter, to receive the web between them. Most webs however
will have body enough to allow the attendant simply to insert the end between
the two rubber rolls R, which will slide it between the stationary guides u, u,
and so deliver it to the carrier guides G, G' between the rolls N, and O, and start
it on its course. These two rolls with elastic surface cannot well be packed to
move airtight against the walls of the chamber, as the sliding roughens the soft
surface. I therefore place outside of them, and in rolling contact with them
two iron rolls I, I', at the side of entrance, and I" and I at the side of exit,
with the two rubber faced rolls pressed between them. These upper and lower
hard faced rolls I, I, I" and I have packings P, P", pressing upon them
from proper recesses, and are practically air-tight in the side of the chamber,

page_text: and the elastic surface of the middle rolls presses against them and against each
other, allowing no air to enter. And when any web of cloth or paper is drawn
in between them, the rubber is compressed enough to allow it to pass without
forcing the rolls apart. In this way I provide for drawing through the machine
a web of cloth or of paper, or warps and yarns of any length. The drying sur-
face is made sufficient, so that at the required speed of passing, these entering
wet will emerge dry, rolls being added if necessary.
A glance at Figure 2 will show that the three cylinders are geared together so
as to secure equal peripheral speed, and the two iron rolls of each pair at the
entrance and exit are also geared together and an intermediate wheel connects
the gears of the cylinders and the gears of the small rolls in a way to secure for
all the same surface velocity. The pairs of iron rolls being driven by power,
the rubber rolls between them are carried at equal speed by surface contact.
If the web shrinks in drying it may be necessary to slightly reduce the peripheral
speed of the rolls at the exit, as may be easily done by adding one or two teeth
to the small gear of I.
For some uses it may be necessary to provide the rubber rolls with scrapers
(doctors), to prevent the web winding upon them, and the stationary guides u, u,
serve both as guides and scrapers, and bent back also serve to screen the rubber
rolls from excessive heat.
It may generally be sufficient to have but one roll with elastic surface
between the two hard faced rolls, and in that case these rolls must rotate in the
same direction, in contact with the elastic roll between them. By a different
arrangement of driers the web might be brought out on the same end of the
machine, as that by which it enters, and possibly one elastic faced roll might
suffice for the machine the web passing in between this and one hard faced roll,
and passing out on the other side of the same rubber roll, and between it and.
the other hard roll, in that case being pressed into the elastic surface, and not
forcing the rolls apart, or allowing the air to enter with it.
For some fabrics greater heat can properly be employed than can be conveyed
by steam without raising the pressure unduly, and for that condition I propose
to use some liquid that has a high boiling point, some oil perhaps, pumping it
around, and this can generally be used without confining it. The use of a liquid
will have the advantage that it is so in contact with the surfaces to be heated
that heat is conducted much more rapidly than from a vapor like steam which
is very important, since the evaporation from the wet web carries away heat with
exceeding rapidity.
The same arrangement allows the use of a liquid heated moderately, and to
a definite, predetermined temperature which temperature would not injure such
material as wet leather. This arrangement for circulating a liquid is illus.
trated fully in Figure 3, where H is the heater, P is the pump, and S, S¹ the
pipes connecting into the hollow journals of the cylinders. This use of a liquid
conveyor of heat will in some cases be of advantage in the drying cylinders of
the ordinary paper machine, and may be used in cylinders not enclosed in a
vacuum chamber.
Some of the advantages of my drier would be secured by carrying the web on
a wire apron or otherwise over heating coils, as indicated by S, S*, of Figure 7,
and for this the higher temperature secured by the liquid would be needed,
heating the fabric mainly by radiation, since the thin air left in the partially
exhausted chamber is so poor a conductor of heat. This treatment would avoid
calendering the surface of fine papers, if desired.
It will be understood that in the arrangement shown in Figure 1 the cylinder C¹
presses against the two cylinders C and C when the web is such that pressure
at these points will be of advantage in drying, squeezing the web, as is likely to
be the case when the web is carried between aprons which pressed against it
absorb its moisture.
The arrangement shown in Figure 7 is a modification of the drier adapted to

page_text: certain kinds of paper.
In this the cylinders, heated through their journals,
are arranged in pairs, three pairs being shown in the drawing, a pair at each end
of the chamber forming the roller gates, and as many pairs being arranged
between as may be necessary to dry the web at the required speed of running.
As here indicated, two endless aprons, A, A, carrying the web W, W between
them enter the chamber B, and are successively squeezed between the cylin-
ders CV,CIV,CIII CII, C₁ C, being separated between each pair of cylinders by the
rollers r,, and after leaving the chamber, returning outside over the guide
rollers R, R. By this arrangement it is apparent that absorbent aprons pressed
against the web between the hot cylinders will absorb much of its moisture by
capillary attraction, and then being separated from it, evaporation will take place
freely from both the web and the two aprons, say from six drying surfaces.
The arrangement that effects this is clearly indicated in the drawing, Figure 7,
but small rollers may also be arranged in a similar way to lift the upper apron
shown in Figure 1, as is plain without illustration. By the use of carrying
aprons it is apparent that, with either arrangement of drying cylinders, the most
delicate webs may be safely carried, since in all close places the web is between
these carriers, and does not itself touch the hot rolls.
The arrangement of aprons or carrying tapes meeting outside the chamber
adapts the drier to carry through it not only webs but also detached sheets, as
of leather-board or straw board, and also loose substances, as wool hair and
the like. It is not intended to limit the claims of the machine to any single use.
It will be understood that this invention admits of much variety in the details
of construction, and that parts of the machine may be omitted or much changed
without destroying its efficiency, and it is not intended to limit the patent to
a machine constructed in minor details precisely as shown. The drying cham-
ber may be used with or without a condenser, it may be heated through the
journals of the cylinders or by steam coils below them, or coils for circulating
oil, and the web and aprons may be carried by a course different from that illus-
trated in the drawings, but the feature of the roller gates and exhausted chamber
cannot be dispensed with, and the machine shown is believed to be the best form
for carrying out the invention.
my
Having now particularly described and ascertained the nature of said in-
vention and in what manner the same is to be performed, I declare that what
I claim is:
1. The process of drying fibrous substances or materials which consists in
subjecting the same, in a closed chamber, to the combined action of an exhaust,
of heat and of motion, as they are continuously carried through the said chamber,
substantially as described.
2. The process of drying fibrous substances or materials which consists in sub-
jecting the same to the joint action of pressure, motion, heat and an exhaust,
while they are continuously carried through a closed chamber, substantially as
specified.
3. A vacuum web drier, consisting of a closed chamber communicating with
an exhauster, means for heating the interior of the same, rolls in pairs, rolling
against each other, and suitably packed against the walls of the said chamber,
forming roller gates through which the web may be rolled into and out from
the chamber, while these rolls with the web between them close the openings
against the admission of air, and connecting mechanism whereby the rolls of
the said gates and all the parts in contact with the web are moved with the same
surface velocity, substantially as described.
4. A vacuum web drier, consisting of a closed chamber connecting with an
exhauster, means for heating the interior of the same, two rolls rolling against
each other, suitably packed against the walls of the vacuum chamber, driven
by power, and adapted to carry the web between them into the vacuum chamber

page_text: without admitting air, and two similar rolls, similarly placed, and adapted to
roll the said web out from the said chamber, substantially as herein set forth.
5. In a vacuum web drier, the combination of the vacuum chamber, the heat-
ing surface within it, the moving rolls in pairs, forming roller gates, closing the
entrance and exit of the said chamber against the pressure of the external air,
and an exhauster, arranged for joint action as herein set forth.
6. In a vacuum web drier, the combination of the vacuum chamber, the heat-
ing surfaces within it, the moving rolls in pairs, forming roller gates, closing
the entrance and exit of the said chamber against the pressure of the external
air, and a condenser and an exhauster, arranged for joint action, substantially
as specified.
7. A vacuum web drier, consisting of a closed chamber connecting internally
with an exhauster, and having entrance and exit openings for the web, pairs of
feed rolls, one or both of each pair with elastic surface, tightly closing the
entrance and exit openings, and adapted to draw in and feed out the web to be
dried, and moving heated surfaces around which this web is stretched, geared
to move with the same surface velocity as the web, and adapted to carry it for-
ward while evaporating the water from it, substantially as specified.
8. A vacuum web drier, consisting of a closed chamber, having entrance and
exit openings for the web, pairs of feed rolls, one or both of each pair with
elastic surface, closing these entrance and exit openings, and adapted to con-
tinuously draw in and feed out the web to be dried, and a series of cylinders
heated through their journals, and arranged to hold the web in contact with a
considerable part of their heated surfaces, while moving it forward, the said
cylinders being connected to each other and to the two pairs of rolls by gearing
and rolling contact, whereby all have practically the same surface travel, in
combination with exhausting apparatus, substantially as herein set forth.
9. In apparatus for drying webs of cloth or paper, the combination of a closed
chamber connecting internally with an exhauster, and having entrance and exit
openings for the web, pairs of feed rolls, one of each pair with elastic surface,
tightly closing these openings, and adapted to continuously draw in and feed
out the web to be dried, and rotary hollow cylinders, over the surface of which
the said web passes, geared to move with the same surface speed as the web,
and adapted to carry the web forward, while evaporating its moisture, a liquid
conveyor of heat, of which the boiling point is higher than the required tempera-
ture of the said cylinders, introduced into these cylinders through their hollow
journals, and apparatus for heating such liquid and circulating it through said
cylinders, whereby the heat of their surfaces in contact with the web is main-
tained at the predetermined temperature best suited for co-operating with the
exhaust in treating the particular material of this web, substantially as specified.
10. In a vacuum web drier, in combination with the exhausted chamber, and
with the moving heated surfaces within it, two series of endless metallic tapes,
carrying rolls having grooves by which these tapes are guided, the said tapes
stretched around and travelling by the path in which the web is to move, each
series of tapes made up of several such tapes, spaced near each other, and the two
series adapted to receive the said web between them, and hold it to its course
while sufficiently exposing it to permit free evaporation, substantially as set
forth.
11. In a vacuum web drier, a closed chamber connecting internally with an
exhauster, means for heating the interior of the same, rolls in pairs
packed against the walls of this vacuum chamber, rolling against each other,
and forming roller gates by which the web may be rolled into and out from
the said chamber, an endless apron or series of guide tapes passing through the
said chamber, and adjustable guide or tightening rollers, substantially as
described.
12. In a vacuum web drier, a closed chamber connecting internally with an
exhauster, means for heating the interior of the same, rolls in pairs packed

page_text: against the walls of this vacuum chamber, and rolling against each other, and
forming roller gates by which the web may be rolled into and out from the said
chamber, and two series of endless tapes, or two endless aprons carried over
rollers, arranged to meet at the entrance and to receive the wet web between
them and carry it through the chamber, substantially as described.
13. In a vacuum web drier, in combination with the closed chamber and its
exhauster, a series of rolls between which the web to be dried may enter the
chamber, and a similar series between which it may pass out, the outer two
rolls of each series having a hard smooth surface, packed against the walls of
the chamber, and the middle roll or rolls being of elastic surface, in rolling con-
tact with the outer two rolls, and adapted to close upon the web and prevent the
air from entering, substantially as herein specified.
NII: 05th day of Ontahan 1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.