Improvements in Electrically Heated Rolls for Drying Paper or Fabric and for similar purposes.
Year: 1898

page_text: Improvements in Electrically Heated Rolls for Drying Paper or
Fabric and for similar purposes.
I, FRED PEARLY SNOW, of 15, Rockingham Street, Lynn, Essex County, State
of Massachusetts, United States of America, Electrician, 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; -
My invention relates to electrically heated rolls that may be used for drying
fabrics or paper, for calendering and for other kindred purposes. The object of
the invention is to apply to the heating of such rolls the familiar principle of
electrical induction. To accomplish this object I use a hollow roll, having an
internal shaft, which is encircled by an annular core, wound with insulated con-
ductor. By this arrangement a secondary circuit through and about the annular
core, is made to consist of the cylindrical wall, the heads and the shaft, of the
hollow roll. By locating the principal resistance of the secondary circuit in that
wall I cause heat to be generated in that part of the roll which needs to be heated.
The best manner in which I have contemplated applying the principles of my
invention is illustrated by the accompanying drawings. Figure 1 is a side view
of an electrically heated roll that is constructed in accordance with those principles.
Figure 2 is an end view of the same roll. Figure 3 is a longitudinal axial section
of Figure 1; and Figure 4 is a cross section on line xx of Figure 1. Figure 5 is
a detail.
The roll that is depicted in these views has a hollow cylindrical shell 1, which
is formed of iron, or of other metal of low electrical conductivity, is thickest at
the middle, and diminishes in thickness gradually toward the ends of the shell,
as shown in Figures 3, 4 and 5. Figure 5, being an enlarged detail from Figure 3,
is a longitudinal section through the wall of the shell. The numerals 2 and 3.
denote two parallel disks of copper, or of other highly conductive material, which
constitute the heads of shell 1, and are united therewith by brazing or soldering. In
the middle of the roll is a large shaft 4, which is made of copper, or of other highly
conductive material, and is integrally or closely united with the heads 2 and 3.
Into the opposite ends of shaft 4, and through heads 2 and 3, are driven the
gudgeon-like bearing-pieces 5 and 6, whereby the roll is mounted for rotation in
suitable supports, not shown in the drawings. In the annular space 14, that is
included between the shell 1, the heads 2 and 3 and the shaft 4, is an annular
laminated core 7, which is wound longitudinally, in and out, with an insulated
copper wire 8.
This laminated core is preferably formed of soft iron, but may be of any other
817

page_text: magnetic material, that is to say, any material that is capable of easy reversals
of magnetization..
In the said annular space 14, and next to shell 1, may be placed any necessary
or convenient packing of asbestos or other material 13. The ends of wire 8, which
is led through insulating bushings in head 2, are electrically connected respectively
with collectors 9 and 10. These are rings of copper, or like conductive material,
carried by insulating disks 11 and 12, which are keyed to bearing-piece 5, as
shown in Figure 3.
Such being the construction of my improved roll, as shown in the said draw-
ings, its mode of operation is easily understood. The entire described mechanism
is rotated bodily by belt and pulley, or by other suitable means, not shown in the
drawings, and at the same time, an electric current of the alternating type, is
supplied, from any suitable generator, to the collectors 9 and 10, and thence to
the primary circuit 8. Thus a current is generated by induction in the secondary
circuit through the shell 1, the heads 2 and 3 and the shaft 4. By this induced
current the shell 1, having less conductivity than the other parts of the secondary
circuit, is heated to any necessary or desired extent, the amount of heat being
regulated and determined, in view of the work to be done, either by the regulation
of the current that is supplied to the primary circuit, or by other appropriate
means, not shown in the drawings. At the same time a uniform distribution of
heat throughout the length of shell 1 results from the described form of that shell
as being of greatest thickness at the middle, and of diminishing cross-section
toward the ends.
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. A hollow cylindrical shell of iron, or of other material that has low electrical
conductivity, two cylinder heads of copper or of other highly conductive material,
united with said hollow shell, and a shaft of copper, or of other highly conductive
material, uniting said cylinder heads, in combination with an annular core,
formed of magnetic material, encircling said shaft, and wound with insulated
conductor, all adapted to be rotated about a common axis, substantially as and
for the purpose specified.
2. A cylindrical shell, that has low electrical conductivity, two cylinder heads,
formed of highly conductive material, united electrically with that shell, and a
shaft, formed of highly conductive material, uniting said cylinder heads, and
provided with terminal bearing-pieces, in combination with an annular core,
formed of magnetic material, wound with insulated conductor, and encircling said
shaft, all arranged symmetrically about a common axis of rotation, substantially
as and for the purpose specified.
3. A hollow shell, formed of iron, or of other material of low electrical con-
ductivity, and having its wall of predetermined cross-sectional area, increasing
toward the middle, and diminishing toward the ends of said shell, two cylinder
heads, formed of highly conductive material, and electrically united with said
hollow shell, a shaft, formed of highly conductive material, and electrically unit-
ing said cylinder heads, and an annular core, formed of magnetic material, wound
with insulated conductor, and encircling said shaft, in combination with current
collectors, connected with said insulated conductor, all being rotable about a
common axis upon suitable bearings, substantially as and for the purpose specified.
4. A hollow cylindrical shell, that has low. electrical conductivity, two cylinder
heads that are formed of conductive material, and are united with said shell, a
magnetic core, which is contained in said shell, and is wound with insulated con-
ductor, in combination with a shaft, that is formed of conductive material, uniting
said cylinder heads, and is provided with terminal bearing-pieces, and with rotary
current collectors for supplying current to said insulated conductor during rotation,
substantially as and for the purpose specified.

page_text: 5. An annular core, wound with primary conductor, and contained in a rotary
shell, which forms the choking portion of a secondary circuit about the same core,
substantially as and for the purpose specified.
Dated this 12th day of July 1898.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.