IMPROVEMENTS IN THE CONSTRUCTION OF ROLLERS FOR CALENDERING AND OTHER PURPOSES."
Year: 1881

page_text: LETTERS PATENT to Wilhelm Richard Schürmann, of Düsseldorf, in the
Empire of Germany, Engineer, for an Invention of "IMPROVEMENTS IN THE
CONSTRUCTION OF ROLLERS FOR CALENDERING AND OTHER PURPOSES."
PROVISIONAL SPECIFICATION left by the said Wilhelm Richard Schürmann
at the Office of the Commissioners of Patents on the 28th January 1881.
WILHELM RICHARD SCHÜRMANN, of Düsseldorf, in the Empire of Germany,
Engineer. "IMPROVEMENTS IN THE CONSTRUCTION OF ROLLERS FOR CALENDERING
AND OTHER PURPOSES."
Experience has proved that the rollers used for calendering and other purposes,
whether made of solid metal and having their journals formed in one with the
body, or made hollow and fitted with a separate axle, are liable to deflection when
subjected to any considerable strain.
It will be found that a pair of such rollers (each truly cylindrical) when working
together, will touch only at their extremities, while they yield midway of their
length to the strain caused by the material to be rolled or calendered passing
between them. This fact is productive of serious inconvenience, which varies in
degree according to the nature of the material operated upon, and the pressure
required to be imparted.
To obviate this inconvenience, rollers have been formed slightly swelling in
diameter towards their middle, their periphery, appearing in longitudinal section
slightly arched.
This shape ensures a uniform action throughout the entire length of the working
line of the rollers, provided such pressure is kept within well known and narrow
limits. Under a less pressure however these rollers will touch only midway of
their length; and, again, under a greater pressure they will touch only at their
extremities, since their deflection varies according to the pressure put upon their
journals.
A uniform pressing action along the entire working line of such rollers is thus
only possible when a given pressure is maintained, which however is a matter of
much difficulty in practice.

page_text: The object of my Invention is to construct rollers which, tho' subject to
variable pressures on their journals, may nevertheless impart an equable and
uniform pressure to the material under treatment along their entire working
line.
In carrying my Invention into effect I take a cylinder of iron having journals
formed in one therewith, and in each end of this roller I cut or "spare out a deep
annular groove (of slightly tapering cross section) extending inwards for about one
third the length of the said cylinder, thus leaving at each end of the roller a
central core of solid metal slightly tapering in form connected with the solid
central portion of the cylinder, and terminating in the journals above mentioned.
A roller thus constructed will be solid for about the middle third of its length,
and the end portions will be susceptible of a certain amount of spring or deflection
owing to the deep annular groove around the slightly tapering core of metal at
each end.
The effect of this principle of construction may be ascertained by taking an
extreme case in which the solid central portion is, extremely narrow in proportion
to the length of the "spared out" ends, for if pressure were brought to bear on the
journals of a roller thus constructed, it is obvious that any deflection which might
result would be limited to the two cores, and that the contact surface of the roller
would remain straight.
For practical reasons however.the.solid central portion of the roller cannot be
made so extremely narrow; but assuming one-third of the, entire length of the
röller to be a fair standard of length for the solid portion thereof, then the said
solid portion will also have a tendency to deflection; this tendency will however
be counteracted by the compressing strains produced toward the "spared out" ends
of the roller.
The proportion as to length which the solid central portion of the roller should
bear to the entire length thereof, and the mean distance apart of its journals may
be easily calculated; but roughly speaking, for a roller whose journals project an
ordinary distance the solid central part should be about one third of the entire
length of the body of the roller.
Instead of forming the rollers and cores out of one piece of metal, it will, in
most cases (for chilled iron rolls for example) be preferable to insert a special axle
of steel or other durable and elastic material, the ends of such axle forming the
journals of the roller.
In this case, the centre of the metal cylinder would first be bored out longi-
tudinally, and the ends of such bore enlarged conically. The separate axle would
then be inserted and firmly secured to the inner periphery of the central portion of
the roller with which portion only of the roller the axle would be in contact.
As a modification of the above arrangement a cylinder of metal might be
constructed to rotate on the central portion of a fixed axle being held in place
thereon by conical sleeves of metal slipped over the slightly tapered ends of the
fixed axle and bearing against shoulders formed in the cylinder of metal.
In this case lubrication of the friction surfaces would be provided for by a central
hole drilled longitudinally of the axle, such hole being provided with an oil
receptacle and communicating with another hole leading radially to the periphery
of the axle midway of the surfaces in frictional contact.
Rollers constructed on the principles above set forth can also work with truly
cylindrical rollers of the ordinary construction, because the bodies of the former, if
not too thick in metal, are able to adapt themselves closely to the said ordinary
rollers when deflected, even if they should have a strengthening collar at the ends
of their bodies.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Wilhelm Richard Schürmann in the Great Seal Patent Office on
the 28th June 1881.
WILHELM RICHARD SCHÜRMANN, of Düsseldorf, in the Empire of Germany,
Engineer. "IMPROVEMENTS IN THE CONSTRUCTION OF ROLLERS FOR CALENDERING
AND OTHER PURPOSES."
It is well known that the rollers used for calendering and other purposes, whether
made of solid metal and having their journals formed in one with the body, or
made hollow and fitted with a separate axle, are liable to deflection when subjected
to any considerable strain. It will be found that a pair of such rollers (each truly
cylindrical) when working together will touch only at their extremities, while they
yield midway of their length to the strain caused by the material to be rolled or
calendered passing between them. This fact is productive of serious inconvenience
which varies in degree according to the nature of the material operated upon and
the pressure required to be imparted.
To obviate this inconvenience, rollers have been formed slightly swelling in
diameter towards their middle, their periphery appearing in longitudinal section
slightly arched. This shape ensures a uniform action throughout the entire length
of the working line of the rollers, provided such pressure is kept within well known
and narrow limits. Under a less pressure however these rollers will touch only
midway of their length, and again under a greater pressure they will touch only at
their extremities, since their deflection varies according to the pressure put upon
their journals.
A uniform pressing action along the entire working line of such rollers is thus
only possible when a given pressure is maintained, which however is a matter of
much difficulty in practice.
The object of my Invention is to construct rollers which, though .subject to
variable pressures on their journals, may nevertheless impart an equable and
uniform pressure to the material under treatment along their entire working line.
The means whereby I attain these results will be readily understood on reference
to the accompanying Drawing.
In Figures 1 and 2 I have shewn the more clearly to explain my Invention two
rollers of a well known type in longitudinal section. In Fig. 1, A is the body of
a solid metal roller, and B, B, the turned journals formed in one therewith.
Fig. 2 represents a hollow roller A fitted with a separate axle B¹, the ends B
of such axle constituting the journals upon which it rotates. In Fig. 3 I have
shewn in longitudinal section a roller constructed according to my present
Invention.
This roller A is constructed of solid metal (with journals B, B, cast in one there-
with), and at each end of the roller a deep annular groove or recess b, b, is formed.
Each of these annular grooves b, b, extends inwards for about one third of the
entire length of the body of the roller, and leaves, as will be seen, at each end of
the roller a central portion or boss c of solid metal, which practically forms part of
a short axle terminating with the journal B and uniting it with the solid middle
portion a of the body of the roller. The outer extremities a', a¹, of the body of
the roller are thus left as it were unsupported, while they are nevertheless of
sufficient strength to resist or counteract the tendency of the roller to deflect along
its axis.
It will thus be seen that on pressure being applied to the surface x, y, of a
roller thus constructed, whereby pressure will be at once thrown upon the journals
B, B, in the direction of the arrows, Fig. 3, the central portions c, c, will have a
tendency to deflect. Now if the solid middle portion a of the body of the

page_text: roller A be supposed, for the sake of argument, to be infinitely narrow, it is obvious
that the deflection of the central portions c, c, would not disturb the equality of
pressure along the working line x, y, of such a roller.
Practical reasons however demand that the solid middle part a. should be of
substantial breadth, as shewn in the Drawing, Fig. 3, and hence this solid middle
portion a will exhibit a tendency to deflect along with the central portions c, c.
This tendency of the solid middle portion a to deflect will however be counteracted
by reason of the more powerful compressing strains produced towards the
annular grooves b, b, forming the unsupported ends a', a', of the body of the
roller.
By paying due regard to the length of the body of the roller and the degree of
projection of the journals upon which it rotates, the proportion which the middle
portion a should bear to the rest of the roller may be easily calculated.
Deflection will be avoided in each case wherein the forces bearing upon the
working line and tending to deflect the middle portion of the roller are exactly
balanced by the counteracting forces derived from the resistance offered by the
unsupported extremities a¹, a', of the body of the roller A.
For a roller, the journals of which project a fair average distance, the solid
middle portion thereof may be about one third (/sra) of the entire length of the
body. It may even bear a rather larger proportion than this to the length of
the body if special circumstances render it advisable, or if a slight deflection of the
roll is immaterial.
In Figures 4 and 5 I have shewn in longitudinal section two composite rollers
constructed according to my Invention.
Instead of forming the rollers in one piece out of solid metal it will be preferable
in most cases (for chilled iron rolls for example) to insert a special axle of steel
or other durable and elastic material, as shewn at B¹, Fig. 4, the ends of such
axle forming, as in Fig. 3, the journals upon which the roller A rotates.
In this case the centre of the metal cylinder A. would first be bored out longi-
tudinally, as at a, Fig. 4, and the separate axle B' would then be inserted and
securely attached to the roller A by shrinking the latter upon it, or in any other
convenient manner, forming a practically homogeneous roller, similar in all essential
respects to that shewn at Fig. 3.
It will be remarked that in this case the annular spaces b, b, taper inwards from
the extremity of the roller, and similarly the central axle B¹ is made of tapering
form towards its ends. This tapering is not however necessary when the roller
and axle are cast in one.
As a modification of this arrangement a cylinder of metal A (see Fig. 5) might
be constructed to rotate upon the middle portion of a fixed axle B¹, being held in
place thereon by means of a collar and a conical sleeve b', 6', slipped over the
tapered end of the fixed axle B¹ and bearing against the middle portion a of the
cylinder A. In this case lubrication of the friction surfaces would be provided for
by oil passages d, e, formed by drilling the axle B₁ radially and longitudinally
as shown in the Drawing, such passage being fed with oil from a lubricator
through a tube f.
Rollers thus constructed may be used in combination with truly cylindrical
rollers of the ordinary construction (as shewn in Figures 1 and 2) which, when
pressure is put upon their journals, show a concave deflection along their working
line, because the bodies of the first named rolls, if not too thick in metal, are able
to adapt themselves closely to the curved rollers even if they should have a
strengthening collar at the ends of their bodies.
Having now set forth the nature of my Invention of "Improvements in the
Construction of Rollers for Calendering and other Purposes," and explained in what
manner the same may be carried into effect, I wish it to be understood that under
the above in part recited Letters Patent I claim,-
The construction and use of rollers for calendering and other purposes, as
described with reference to Figures 3 to 5 of the Drawing, the said rollers having

page_text: spaces or grooves, as at b, b, formed in their end portions and extending inwards to
the central or solid portion a of the roller, whereby the deflection of the body of
the roller when pressure is put upon its journals is diminished and the body of the
roller is better enabled to adapt itself closely to plane or curved surfaces.
In witness whereof, I, the said Wilhelm Richard Schürmann, have hereunto
set my hand and seal, the Twenty first day of May, in the year of our Lord
One thousand eight hundred and eighty-one.
W. R. SCHURMANN. (L.S.)