Improvements in and connected with the Method of and Apparatus for Drying the Wet Felt of Paper-making Machines.
Year: 1899

page_text: Date of Application, 23rd May, 1899-Accepted, 15th July, 1899
COMPLETE SPECIFICATION.
Improvements in and connected with the Method of and Apparatus
for Drying the Wet Felt of Paper-making Machines.
We, HANS NEIDHARDT, of 7, Gerichtstrasse, Chemnitz, Kingdom of Saxony,
in the Empire of Germany, and HERMANN SCHULTE, of 37, Währingerstrasse,
Vienna, in the Empire of Austria, both Civil Engineers, 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:-
The wet felt used for long wire-and cylinder machines are, after washing,
usually dried by hanging them on rods either in the open air or in closed rooms,
and there left until the condensed water is entirely evaporated. As this goes
on very slowly, taking 2 or 3 days in summer and 4 to 6 days during the other
seasons of the year, the fabric loses its strength, and the time during which it
may be used decreases considerably after each drying.
A circumstance also contributing to the early wearing out of the felt is that
the fabric continuously becomes longer and narrower on the paper-machine,
the original square meshes becoming more and more contracted and progressively
diminishing the absorption of water from the paper.
This inconvenience may be overcome by means of an apparatus represented
in the accompanying drawings, which not only dries the felt in the shortest
time but also stretches the material in the direction of the breadth. By this
means the injurious influence of moisture on the woollen fabric is obviated and
the meshes are opened anew for the transfusion of the water.
Moreover the fabric remains cleaner, since it becomes impossible for as much
dust or the like, to accumulate, as when hung in the open air for days.
In the accompanying drawings two ways are shewn, of carrying out the
improved drying and stretching machine:
Figs. 1 and 2 giving, the one form, and
Fig. 3 the other;
Figs. 4 and 5 representing details.
A series of rollers are mounted free in the two sidewalls a b of the frame
(Figs. 1 and 2) one of which rollers (e) remains constantly in its bearings, whilst
the others (hik) can be taken out to enable the felt to be interchanged. The
upper pair of rollers (i k) are, furthermore, adjustable in a vertical direction,
so as to make the appliances suitable for felt of various lengths.
The roller c consists of a bronze shell with an interior lining of cast iron.
Arrangements are provided for heating it by steam, the inlet being at d and the
outlet at c, and it is driven by means of the belt pulley f.
gik are stretching rollers, and h is a guide roller.
The stretching rollers g and i are provided with spiral metallic bands on their
periphery, these bands starting from the middle of the rollers and running, in
opposite directions and twist, towards the ends, the result of which is that a
piece of cloth or fabric passed over this part of such rollers is subjected to a
strongly transverse pull. The same purpose is served by the rollers shewn

page_text: diagramatically in Figs. 4 and 5, two conical rollers being shewn in Fig. 4,
tapering inwards to the centre. Use is here made of the well known
phenomenon, that a band-in this case the wide felt a-attempts to draw towards
the thicker part of the roller. As this goes on at the same time in both rollers
the desired stretching of the felt is effected in the direction indicated by the
arrows y. A similar thing occurs in the arrangement given in Fig. 5, where
two rollers engage under the stretched fabric a in such a manner that their axes
of rotation are arranged so as to enclose an obtuse angle. The friction between
the periphery of the rollers and the fabric forces the latter to run off in a direc-
tion at right angles to the axes of the rollers. The paralelogram of forces y v z
shows that hereby a force y is generated which serves to stretch the fabric out
laterally.
To still further ensure this stretching of the felt in a transverse direction
(direction of the weft) a weighting roller is placed on the upper roller i
(Figs. 1 and 2), the periphery of being provided with engraved spiral grooves
corresponding with the projecting (right and left handed) spirals on i. By
this means the felt fed between the two rollers is strongly forced to stretch to
the right and left in accordance with the opposed direction of the spirals.
In order to prevent any tendency of the fabric to draw laterally in a slanting
direction, the guide roller is provided, and can, if necessary, be adjusted some-
what slantwise by means of the set screw h¹.
As already stated, the upper pair of rollers ik is adjustable vertically, this
being effected by the set screws i¹. On taking out the rollers, they are tem-
porarily supported on the rest .
The felt stretching and drying machine shewn in Fig. 3 differs from those
already described, in that the drying cylinder is replaced by a heating apparatus
m m situated in the enclosing chamber m, under the felt cloth, and the stretching
of the fabric in the direction of the warp, is effected automatically by the
weight, by the latter exerting a continuous upward draft on n.
In place of the heating pipe, other forms of heating bodies can of course be
used, such at hot air allowed to escape underneath the felt cloth.
The rollers n o p q r s, have in general the same form and use as the rollers gh
ik in Figs. 1, 2, 4 and 5.
Both in the arrangement shewn in Figs. 1 and 2, and that in Fig. 3, an
appliance consisting of roller brushes tu can be interposed, with the object of
exercising a loosening action on the surface of the fabric, so that the small hairs
on the surface of the felt, that have been twisted and entwined during the using
of the felt in the paper machine, are again straightened and so do not close the
pores of the fabric.
The mode of working the improved apparatus culminates, as can be seen, in
the restoration of the felt, which while in use in the paper machine, has become
impenetrable and wet--to a condition as closely as possible resembling that of
new felt, which, as is well known, is loosely woven from coarse woollen yarn and
is neither raised nor shorn. It is just this loosely woven structure that is of
special value for the satisfactory action of the felt, since it is desirable, that the
felt should be in a high degree permeable to water. In order to restore this
permeability to the used felt, it is not sufficient to dry and stretch the material,
but the fabric must be subjected to a very frequently repeated stretching and
releasing during the drying process. Only in this manner can a uniform
loosening of the fabric be attained.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
1. The improved method for drying the wet felt of paper-making machinės,
substantially as set forth.
2. The improved apparatus for drying the wet felt of paper-making machines

page_text: characterised by the combination of heating appliances with a series of stretch-
ing rollers, some of which rollers are provided with spiral metallic bands on
their periphery, these bands starting from the middle of the rollers and running
in opposite directions and twist, towards the ends, substantially as and for the
purpose set forth and illustrated in the drawings.
3. The improved apparatus for drying the wet felt of paper-making machines,
characterised by the combination of heating appliances with a series of stretching
rollers, two of them being of conical shape, tapering inwards to the centre, sub-
stantially as and for the purpose set forth and illustrated in the drawings.
4. In apparatus of the kind described in Claims 2 and 3, the employment of a
heating apparatus situated, in an enclosing chamber, under the felt cloth, and
the stretching of the fabric in the direction of the warp being effected automati-
cally by a weight, substantially as and for the purpose set forth and illustrated
in the drawings.
5. In apparatus of the kind described in Claims 2 and 3, the employment of
two adjustable rollers, engaging each other, one of them being provided with en-
graved spiral grooves, and the other with projecting spirals, substantially as
and for the purpose set forth and illustrated in the drawings.
6. In apparatus of the kind described in Claims 2 and 3, the arrangement,
where two rollers engage under the stretched fabric in such a manner, that their
axes of rotation enclose an obtuse angle, substantially as set forth and for the
purpose described, and illustrated in Fig. 5 of the accompanying drawings.
7. In apparatus of the kind described in Claims 2 and 3, the employment of
an appliance, consisting of roller brushes interposed with the object set forth.
Dated this 23rd day of May 1899.