Improvements in the Process and Apparatus for the Papering of. Iron Sheets for Electrical and Magnetical Apparatus.
Year: 1896

page_text: Date of Application, 1st July, 1896
Complete Specification Left, 29th Mar., 1897-Accepted, 15th May, 1897
[Communicated from abroad by SIEMENS & HALSKE, of 94 Markgrafenstrasse,
Berlin, in the German Empire, Electrical Engineers.]
Improvements in the Process and Apparatus for the Papering of.
Iron Sheets for Electrical and Magnetical Apparatus.
We, SIEMENS BROTHERS & Co., LIMITED, of 12 Queen Anne's Gate,
Westminster, in the County of London, Electrical Engineers, do hereby declare,
the nature of this invention to be as follows:-
The construction of the iron portions of electrical and magnetical apparatus of:
separate plates insulated from each other by interposed paper, in order to avoid
Foucault currents, is well known.
Hitherto the pieces of iron plate and of paper have been separately cut out, and
then placed together alternately.
This operation involves double labour in the cutting out of the pieces and
requires great care in dealing with the tender paper especially when slots or holes"
have to be cut, and in making sure that there are no defects in the insulation...
Our invention relates to means of overcoming these difficulties by covering one,
side of the iron sheet in the first place with the paper cemented to it by any
suitable medium such as starch paste, and then cutting out the pieces and laying"
them together.
Otherwise, both sides of the iron sheet can be covered with the paper, the
pieces so covered being laid up alternately with pieces that are not papered.
Certain practical difficulties are met with in covering the iron with tender paper,
especially when it is moist, as rents, folds, air bubbles, and inequalities in the
thickness of the cement are liable to occur. In order to avoid these and other'
difficulties, and to effect the papering at moderate cost, we operate with apparatus
of the following kind.
On a horizontal frame we mount at suitable distances apart. three pairs of
horizontal rollers, the first pair feeding successive sheets of iron towards the
second pair, where the papering is effected, and the third pair discharging the
papered sheets. An operator at the first pair of rollers can, by means of a lever,.
separate them so as to introduce a fresh sheet between them, and then by a crank
on the axis of the lower roller can advance the sheet so as to overtake the previous
sheet which is being moved onwards by the second pair of rollers.
paper
Froin a paper roll above, provided with a light brake, a continuous sheet of
is led obliquely down to the bite of the second pair of rollers, and, cement
being fed between the paper and the iron, both pass together between the rollers
by which they are pressed together, the surplus cement being pressed out.
The upper roller of this pair, which bears upon the paper, is covered with
elastic material such as caoutchouc and is kept moistened by a little water to
prevent the paper from adhering to it.
From the second pair of rollers the papered iron sheet travels over a heated
table, the cement being thus dried and set, and finally the prepared iron sheet*
is discharged from the third pair of rollers.
When it is desired to paper both sides of the iron sheet, it is passed vertically,
;

page_text: down between a pair of rollers mounted side by side, along with two sheets of
paper brought, one on each side, obliquely to the bite of the rollers; which dip
into water troughs for the purpose of keeping them clean.
The sheet thus papered passes down between two heaters by which the cement is
dried and set.
ABEL & IMRAY,
Agents for the Applicants.
Improvements in the Process and Apparatus for the Papering of
Iron Sheets for Electrical and Magnetical Apparatus.
We, SIEMENS BROTHERS AND COMPANY, LIMITED, of 12, Queen Anne's Gate,
Westminster, in the County of London, Electrical 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 construction of the iron portions of electrical and magnetical apparatus
of separate plates insulated from each other by interposed paper, in order to
avoid Foucault currents, is well known.
Hitherto the pieces of iron plate and of paper have been separately cut out
and then placed together alternately.
This operation involves double labour in the cutting out of the pieces and
requires great care in dealing with the tender paper especially when slots or
holes have to be cut, and in making sure that there are no defects in the
insulation.
The present invention relates to means of overcoming these difficulties, which
consist in covering one side of the iron sheet, at the commencement of the
manufacture, that is to say before they are cut to shape, with paper cemented
thereto by any suitable material, such as starch paste, after which the sheet is
treated in the usual manner without reference to the paper covering, with the
exception that in fitting together the sheets forming the electro magnet bodies, the
papered side will always have to be placed in the same direction.
The cementing on of the paper can be effected in any known manner either
mechanically or by hand. Instead of covering only the one side of the sheet metal
with paper, both sides may be covered, in which case in building up the electro-
magnet body, such covered sheets are arranged alternately with sheets having no
paper covering. By this means only half the metal sheets employed require to be
treated.
In either of the above cases certain technical difficulties arise in the covering. In
the first place, in particular when using very thin tissue paper it is difficult to cement
the same on in large sheets without the occurrence of tears, folds, and air-bubbles,
as the paper loses its strength almost completely on moistening, and owing to its
porosity the cementing material will readily pass through it to the other side,
causing it to adhere to the appliance, such as a roller, etc., by which the paper is
pressed against the metal.
It is also of great importance that, directly after the cementing-on, all the
moisture contained in the cementing material shall be removed in order to prevent
the formation of rust and the accidental adhering together of prepared sheets
stacked one upon the other, or coiled up in rolls.
Lastly, it is essential that the layer of cementing material between the paper
and sheet metal shall not be of unequal thickness, and that only the minimum
quantity necessary for the cementing together, shall be used.

page_text: In order to avoid these difficulties and to effect the papering at a moderate cost,
we employ for the above purpose a machine constructed as we will describe with
reference to the accompanying drawings, in which
Figure 1 shews a side view of the machine, and Figure 2 a perspective view
thereof;
Figure 3 shews a modification for coating both sides of the sheet metal.
On a framing A are mounted two rollers B and B to which a uniform rotary
motion is imparted in contrary directions; between these rollers are passed the
sheet metal and the paper D, between which is introduced the cementing
material E, the combined sheet metal and paper being then passed over the heated
drying frame F. The rollers B B, or at any rate that over which the paper.
passes, is preferably provided with a covering of caoutchouc in order to adapt
itself better to the unevennesses of the sheet metal.
For coating one side only of the sheet metal, the rollers B B are preferably
mounted one above the other, as shewn at Figures 1 and 2, the sheet metal being
supplied from below and the paper from above. The paper is drawn from a
continuous roll G while the sheet metal may either also be supplied from a
continuous roll or in separate sheets. In the latter case the sheets are preferably fed
towards the covering rollers by being passed between a pair of feeding rollers HH,
having the same surface speed as the rollers B B. The cementing material, such
as starch paste E which is fed in between the sheet metal and paper just before their
entrance between the rollers B B, is squeezed back by the latter so as only to leave
just sufficient between the paper and inetal to ensure the proper cementing together
thereof. The paper is only moistened just before its union with the metal, so that.
being uniformly supported by the latter along its entire width, it possesses sufficient
strength for drawing round the roll G, which is subject to sufficient frictional
resistance to keep the paper slightly stretched.
For maintaining this strain uniform with a gradually decreasing diameter of the
roll G, the axis of the latter carries a brake disc J on which brake blocks K
slide that are gradually moved inwards as the diameter of the roll decreases by a
lever arm K with roller resting on the roll G. Of course other means may be
adopted for accomplishing this object.
The feeding rollers H H which fulfil the additional function of smoothing down
any sharpnesses on the edges of the sheet metal and thus protecting the caoutchouc
covering of the rollers B B2, can, in the case of comparatively small sheets of
metal, be provided with a device L and M which enable them to be occasionally
moved apart, and to be turned by hand independently of the gearing N of the
machine. The object of this is to allow of the intermittent supply of the sheets by
the operator.
While the sheet C' situated between the rollers B B is travelling forward at a
uniform moderate speed, and has nearly passed through, the operator introduces
a fresh sheet C² between the rollers HH2 and turns these rapidly by means of
a crank bandle M, that is fixed on the shaft and is connected by a ratchet and
pawl device with the corresponding driving gear, so that the sheet C is made to
advance quickly up to the end of the sheet C between the rollers B' B³, after
which he moves the rollers slightly apart by means of the lever and wedge
device L, in order to enable him to adjust the position of the sheet C for which
purpose a lateral guide rail may be provided. He then moves the lever L so as
to allow the rollers H to nip the sheet C again, and to feed it forward by means
of the driving gear N until it enters between the rollers B B. It then has
transferred to it the remainder of the paste E squeezed backward from the
plate C fresh paste being added either mechanically or by hand. It is not
necessary to spread the paste uniformly with care, as this is effected automatically
by the rollers B' B.
In order to prevent the paper from adhering to the upper roller B', for which
there will always be a tendency, owing to the paste penetrating through the pores
of the paper on to the surface of the roller B, the latter is continuously cleansed

page_text: and coated with a suitable material that will prevent such adhesion. If starch
paste is used as the cementing material, water may be employed for both the
above purposes. In this case the rinsing and moistening of the roller B¹ is
effected by providing a metal roller O that is pressed against the caoutchouc
covering of roller B' in a lateral position, so as to form a gutter between the two
into which a small stream of water is made to flow from a pipe P at the middle, so
as to flow off at either end, carrying with it the particles of paste washed off the
roller B', and keeping the surface of the latter wet.
As the metal sheet coated with paper leaves the rollers B1 B2 it passes over
a heated drying frame F by which all moisture is evaporated therefrom. Lastly
another pair of rollers QQ also driven by the gearing N, take up the plates (1
after they have left B1 B2 so as to draw them forward over F. If the metal
sheets are to be covered with paper on both sides, the rollers B' B2 are conveniently
arranged side by side as shewn at Figure 3, in which case they may dip at bottom
into water troughs R! R2 for clearing them of adhering paste. The sheet metal C
is in this case passed vertically downwards through the rollers while the paper D¹ D²
is led in at an angle on each side, the paste being supplied at E E. The combined
sheets pass below between two heated drying frames F1 F2.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we declare that what we
claim is :-
1. The process for preparing iron sheets for electrical and magnetical purposes
consisting in cementing paper on one or both sides of the sheets before they are
cut to shape substantially as described.
2. In the process for preparing iron sheets referred to in the first claim, passing
the sheet metal and the paper at an angle to each other between revolving pressing
rollers, the paper sheet being kept stretched by being drawn off a reel offering
a regulated frictional resistance, while the cementing material is supplied between
the metal sheet and the paper at the point where they enter between the pressing
rollers, substantially as described.
3. In a machine for carrying out the process of cementing paper to sheet iron
referred to in the first and second claims, the combination of pressing rollers such
as B1 B2 covered with caoutchouc, through which the metal sheets and paper are
passed and which are provided with means for clearing them of cementing material
that may penetrate through the pores of the paper, a reel such as G from which
the paper is drawn, revolving with regulated frictional resistance, feed rollers such
as H1 H2 for feeding the metal sheets between the pressing rollers, a heated drying
appliance such as over which the combined sheets are passed on issuing from
the pressing rollers, and delivery rollers such as Q1 Q2 by which the combined
sheets are fed forward over the heating device, substantially as described.
Dated this 29th day of March 1897.
ABEL & IMRAY,
Agents for the Applicants.