Apparatus for Casting Printers' Rollers.
Year: 1895

page_text: Date of Application, 28th Oct., 1895-Accepted, 21st Dec., 1895
VUMI LEIDDI BUITIATION.
Apparatus for Casting Printers' Rollers.
We, OTTO LOOSEN, Merchant, of 112, Perlengraben, Cologne, and JOHN
HEINRICH JÜLICHER, Manufacturer, of Heinsberg, both in Rhenish Prussia, 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
In order to obtain clear and sharp impressions from the rollers of typographic
printing presses, it is important that the surface of the rollers, and especially of
those which directly touch the printing surface, should be perfectly uniform and
smooth, free from any faults of casting, such as air channels or bubbles. Such
air-channels or grooves in the surface of the rollers are produced if the casting or
plastic mass and the mould (which has been heated immediately before the process
of casting) are allowed to cool before the air occluded between the said mould and
the roller axle has had time to escape upward. Owing to the viscosity of the mass,
it may enclose large or small quantities of air, (according to its viscosity), which
becomes heated by the said mass and tends to escape upwards.
Hitherto it has been usual to coil a string helically around the spindle, and
sometimes a second coil has been laid over and across the first, in order that the
mass flowing down may adhere to the spindle and not come off after it has cooled.
Now, as the air could not ascend along the rough spindle, it ascended along the
smooth wall of the mould, but owing to the incipient cooling and solidifying of the
mass, it could only penetrate with considerable pressure and by forming zig-zag
grooves.
The channels thus produced receive the air bubbles occluded in the mass and
conduct them upward. The depth of these grooves which appear on the surface
of the roller and produce inequalities of the work, is in proportion to the quantity
of air which had been enclosed.
To avoid such surface grooves and air bubbles care must be taken that only a
minimum of air will enter the mould with the mass, and that the mass may flow
uniformly and unhindered along the core or spindle in the mould prepared for the
process of casting. This requirement not fulfilled by the ordinary method of
casting the mass on the spindle end by hand, or through a funnel, but may be
attained by the use of the apparatus constituting the subject of the present
invention.
A further requirement for the manufacture of faultless printing rollers is the
free ascent of the fluid mass in the mould from the bottom of the same, and this is
attained by our invention chiefly because it depends on the fulfilment of the first
mentioned requirement.
In the accompanying drawings,
Fig. 1 is a vertical section of an apparatus embodying our invention,
Fig. 2 is an elevation of the same,
Fig. 3 a horizontal section along line a-b of Fig. 1.
The apparatus chiefly comprises a funnel A containing near its base a couical
spreader E adapted to distribute the contents of the funnel uniformly on all sides.
Said funnel is provided with three or more discharge tubes B of lead or other
flexible material, the upper ends or inlets of said tubes adjoining the base of the
said spreader and being arranged in a circle around the same.
Fig. 1 shows also the manuer of using our new apparatus in casting a roller.
The funnel A is placed on the reduced extremity C of the upright spindle,

page_text: and the discharge tubes B are made to fit with their lower ends tightly against
the circumference of the roller spindle, for. which purpose the tubes are either
drawn apart or pressed together according to the diameter of the spindle. The
lower ends of the tubes B are provided at their inside with short grooves and
bent inward so as to direct the fluid mass against the surface of the spindle.
If the liquid mass is poured into the funnel A, the cone E directs it uniformly
towards the discharge tubes B, through which it flows down to the outlets
situated at the circumference of the roller spindle or core, and then it runs in
uniform rectilinear streams down to the bottom of the mould.
If the viscous liquid is simply poured on the upper end of the spindle by hand,
it will not spread equally over the circumference and will therefore flow down
the spindle irregularly.
After having arrived at the bottom, the mass will ascend between the spindle
and the wall of the mould, driving out the air until the latter reaches the edge
of the mould and escapes into the atmosphere. With our improved method of
casting, however, very few, if any, air bubbles are formed, and these escape at
the upper edge of the mould. Instead of enclosing the spindle with helically
coiled layers of strings, crossing each other, we fix to it a few vertical strings,
which will not impede the flow of the liquid mass, and if the circumference of
the spindle is made of wood, as indicated by the drawings, or of other porous
material, we may avoid altogether the use of strings.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. Apparatus for the manufacture of printing rollers, comprising a funnel
provided at its base with a conical spreader and with three or more flexible
discharge tubes, the said tubes being arranged around the base of the said spreader
and adapted to enclose with their ends the core or spindle of the roller, substantially
as described.
2. The combination of the spindle or core of a printing roller, with an upright
mould, and a casting funnel constructed and adapted to operate substantially as
described.
Dated this 28th day of October 1895.