IMPROVEMENTS IN DRYING PAPER AND PASTEBOARD IN THE COURSE OF ITS MANUFACTURE, AND, IN THE APPARATUS FOR THAT PURPOSE
Year: 1879

page_text: LETTERS PATENT to Frank Wirth, of the Firm of Wirth and Company, Patent
Solicitors, at Frankfort on the Main, in the Empire of Germany, for the
Invention of "IMPROVEMENTS IN DRYING PAPER AND PASTEBOARD IN THE
COURSE OF ITS MANUFACTURE, AND, IN THE APPARATUS FOR THAT PURPOSE."
A communication from the Society for the Manufacture of Wood Pulp, at
Grellingen. in the Republic of Switzerland.
PROVISIONAL SPECIFICATION left by the said Frank Wirth at the Office
of the Commissioners of Patents on the 19th September 1879.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
Frankfort on the Main, in the Empire of Germany. "IMPROVEMENTS IN DRYING
PAPER AND PASTEBOARD IN THE COURSE OF ITS MANUFACTURE, AND IN THE
APPARATUS FOR THAT PURPOSE." [A communication from the Society for the
Manufacture of Wood Pulp, at Grellingen, in the Republic of Switzerland.]
The present Invention relates to an improved mode of drying continuous paper
and pasteboadr, and in the apparatus employed for this purpose. Heretofore the
paper coming from the pressing machine or other machines was led over heated
metal cylinders, which had the disadvantage that the paper became more or less
brittle, thus rendering impossible the use of mechanically ground unboiled wood
fibre without other admixture, and also that the cost of plant and working was
considerably increased by the necessary employment and working of the expensive
metal cylinders required for the purpose.
The present Invention has for its object to obviate these defects, and consists
mainly in subjecting the paper or pasteboard coming from the long press machine
or other machine to the direct action of heated air, gases, or vapour in one or more
chambers, instead of using heated cylinders for this purpose as heretofore.
The paper receives by this means an increased strength and toughness, because
the paper is perfectly free to shrink to the full extent both in the length and in the
width as it passes from the moist to the dry condition, whereas with the use of
heated metal drying cylinders and felt guides as heretofore this shrinkage could

page_text: not only not take place perfectly but the paper was even stretched longitudinally,
which can only be done at the expense of its strength and toughness.
In addition to the above advantages the cost of plant is considerably reduced by
doing away with the cylinders, and the working expenses are also less as less fuel
for heating is required. The operation is carried out in the following manner :-
The paper, coming in a more or less wet state from the wet long press or other
machine, is conducted by means of guide rollers, guiding felts, cloths, or wire gauze,
or the like, in a horizontal or other direction, through one or more closed chambers
where it is subjected to the direct action of hot air, gas or vapour, until it has been
sufficiently freed from moisture, whereupon it is led through a wet satin press and
is then again subjected to the action of heated air or gas in the same or other
drying chambers until it has attained the same state of dryness as the atmosphere.
Lastly, the paper is passed through a calander on to the winding reel. In order
to economise space in the drying chambers the paper is led backwards and forwards
therein in a zigzag direction by means of rollers arranged in tiers. Between the
adjacent rollers are plates to support the paper. The rollers are driven a little
faster than the paper travels, so that they may have a pushing effect thereon rather
than drag it, and they may be driven by friction discs.
The same process can also be applied, with the necessary modifications, to
pasteboard.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Frank Wirth in the Great Seal Patent Office on the 3rd March
1880.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
Frankfort on the Main, in the Empire of Germany. "IMPROVEMENTS IN DRYING
PAPER AND PASTEBOARD IN THE COURSE OF ITS MANUFACTURE, AND IN THE
APPARATUS FOR THAT PURPOSE." A communication from the Society for the
Manufacture of Wood Pulp, at Grellingen, in the Republic of Switzerland.
The present Invention relates to an improved mode of drying continuous paper.
and pasteboard, and in the apparatus employed for this purpose. Heretofore the
paper coming from the pressing machine or other machines was led over heated
metal cylinders, which had the disadvantage that the paper became more or less
brittle, thus rendering impossible the use of mechanically ground unboiled wood
fibre without other admixture, and also that the cost of plant and working was
considerably increased by the necessary employment and working of the expensive
metal cylinders required for the purpose. The present Invention has for its object
to obviate these defects, and consists mainly in subjecting the paper or pasteboard
coming from the long press machine-or other machine-to the direct action of
heated air, gases or vapour, in one or more chambers, instead of using heated
cylinders for this purpose as heretofore. The paper receives by this means an
increased strength and toughness, because the paper is perfectly free to shrink
to the full extent both in the length and in the width as it passes from the moist
to the dry condition, whereas with the use of heated metal drying cylinders and
felt guides as heretofore this shrinkage could not only not take place perfectly but
the paper was even stretched longitudinally, which can only be done at the expense
of its strength and toughness. In addition to the above advantages the cost of
plant is considerably reduced by doing away with the cylinders, and the working
expenses are also less as less fuel for heating is required. The operation is carried
out in the following manner:-The paper, coming in a more or less wet state from
the wet long press or other machine, is conducted by means of guide rollers, guiding
felts, cloths or wire gauze, or the like, in a horizontal or other direction through one
or more closed chambers, where it is subjected to the direct action of hot air, gas or
vapour, until it has been sufficiently freed from moisture, whereupon it is led
through a wet satin press and is then again subjected to the action of heated air or
gas in the same or other drying chambers until it has attained the same state of
dryness as the atmosphere. Lastly, the paper is passed through a calander on to
the winding reel. In order to economise space in the drying chambers, the paper
is led backwards and forwards therein in a zig-zag direction by means of rollers
arranged in tiers. Between the adjacent rollers are plates to support the paper.
The rollers are driven a little faster than the paper travels, so that they may have
a pushing effect thereon rather than drag it, and they may be driven by friction
discs.
"
The same process can also be applied, with necessary modifications, to pasteboard.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a longitudinal section with the middle part shewn in external elevation
of drying apparatus according to this Invention'; Fig. 2 is a transverse section on
X, X; Figure 3 a transverse section on Y, Y; and Fig. 4 is a plan. From the last
roller a of the paper making machine the continuous sheet 6 in its soft moist

page_text: The end and pressing rollers are driven by bands, and the rollers in the drying
chamber are driven by friction from dises on a shaft k. The rollers leading the
paper into and through the drying chamber are driven a little faster than the paper
is supplied, so as to have a pushing action on it and not to subject it to any tearing
strain. Between the rollers in the drying chamber are plates i which support the
sheet. The heated air supplied from a stove p flows as indicated by the arrows in
a direction opposite to that in which the paper is travelling, finally passing by a
fluer below the chamber to the chimney T. The guide rollers g may be heated,
and instead of hot air hot gases or superheated vapours may be transmitted through
the drying chamber, and the direction of their movement may be varied if desired. 1
Having thus described the nature of the said Invention, and in what manner the
same is to be performed as communicated to me by my correspondents, I claim,-
First. Drying and rendering firm paper or pasteboard as it comes in a continuous
web from the paper making machine, by passing the web over guide rollers through
a chamber through which hot air or gas is caused to circulate, substantially as
herein described.
Second. The construction and arrangement of apparatus for drying and rendering
firm a continuous web of paper or pasteboard, as herein described with reference to
the accompanying Drawings.
1
In witness whereof, I, the said Frank Wirth, have hereunto set my hand and 2
seal, this Twenty fifth day of February, in the year of our Lord One
thousand eight hundred and eighty.
FRANK WIRTH. (L.S.)