Improvements in or connected with Grinding Machines or Apparatus for Bevelling or Chamfering.
Year: 1892

page_text: Date of Application, 8th Dec., 1892-Accepted, 4th Feb., 1893
Improvements in or connected with Grinding Machines or
Apparatus for Bevelling or Chamfering.
A communication by Max OffenBACHER, of Fürth, Bavaria, in the Empire of
Germany, Inventor.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool and 6, Bank Street,
Manchester both in the County of Lancaster and 323 High Holborn in the
County of Middlesex, Civil Engineer, 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:-
This invention relates to that class of facet-grinding machines in which plane
facets are obtained by pressing the inclined placed rotating object to be ground
against the cylindrical circumference of the grinding-cylinders (iron, stone or felt
cylinders).
The object of this invention is to make machines of this kind more suitable and
valuable for practical use by material improvements in their construction.
For this purpose the working piece is arranged, otherwise than is generally the
case approximately horizontal, under the cylinder, which position is more con-
venient for the attending workman and affords him a better opportunity for
watching the grinding process, moreover the supporting frame is so constructed
connected with an upright stand, that it can be moved in very many different ways
for moving in and out, pressing upon or moving the object to be ground, and for
changing its position, and also for the changing of the angle of the facet. Of
especial importance, moreover, is the arrangement for regulating pressure to obtain
facets of equal width.
The facet-grinding machine working in the manner just mentioned is of
the following nature, as may be better seen with reference to the drawing,
in which
Figure 1 is a side elevation of the improved machine, partly in section ;
Figure 2 is a front view of the same; and
Figure 3 represents a front view and side view, partly in section, of the pressure
device.
Like letters represent corresponding parts.
The grinding-cylinder (grindstone) a rests with its horizontal shaft on the
frame A, is rotated in the usual manner, and is, at the same time, moved back and
forth in the direction of the shaft.
Below this cylinder is placed the object, that is, the plate of glass c to be ground.
This is inclined under the acute facet angle towards the horizontal shaft, and, since
this angle is very small, occupies an almost horizontal position.
When the plate, in this inclined position, is pressed against the surface of the
cylinder, which is at the same time rotated on its own shaft, the consequence is that
the object is given a flat facet, according to the facet-angle which has been previously
determined upon.
To attain this, the plate of glass c is fastened in any well known way upon a
plate d, the shaft e of which rests in an adjustable frame B and is provided at its
lower end with a gear wheel meshing into a gear wheel g on the main driving
shaft h, by means of which the shaft e is rotated. The gear-wheel motion is of
importance for the grinding-machine in question, in combination with the adjust-
ability of the frame B already mentioned as the moving in and out of the rotating
object is produced by the lateral rotation of the frame, that is, by the approaching
or withdrawing of the gear wheel f, connected with it, from the spiral g without
Price 8d 1

page_text: necessitating a separate mechanism for throwing it out of gear (as a belt-shifter,
etcetera).
In order to give the object-holders movement in different directions, the frame
is attached to an upright stand C and can be rotated about a horizontal pin i at a
right angle to the direction of the shaft b of the cylinder.
By rotation on this pin, the suspension, that is, the change of the facet-angle is
effected; the position of the frame in each case being fixed by the turning of
a nut i.
Moreover, the frame B can be rotated about a second horizontal pink parallel
to the shaft b of the cylinder, and thereby the object may be made to approach the
circumferences of the grinding cylinder or to recede from it. The contact between
object and cylinder is produced automatically by an arm B' lying on the side
opposite to that of pivot k, which arm is provided with a movable weight l.
The weight in this case restores the equilibrium, when the contact mentioned is
made. The grinding pressure proper is produced, not by this weight as is the
usual method, but by a special mechanism which will receive more detailed
description further on."
This frame movable in the two directions mentioned, is fastened to a horizontal
support m also supporting pins ik. This support m can be moved perpendicular
to the direction of the main cylinder shaft or the guide n.
By these means shaft e according to the size of the piece of glass to be ground,
is moved to or from the frame A so that thereby it is possible within suitable
limits to work glasses of different diameter with the same machine.
Guide n is moved on a second plate o which can be moved on a guide ? parallel
to the cylinder shaft. Hereby without otherwise changing its position, the object
can be moved along the cylindrical surface of the grinding cylinder and therefore,
when one part of the cylinder is worn another part or even the whole length can
be used.
The last mentioned carriage guide prests on a cylindrical support 7 that is fitted
into the upper end of the hollow stand C. By turning support 9 the whole frame
just described is turned on its axis a and thereby, according to the direction of the
rotation, the gear wheel is brought into or out of contact with the worm gear g
and the object is moved in or out. The position in each case can be fixed by an
adjustment screw 5.
In addition to the above mentioned varied movableness the generation and
regulation of the pressure necessary for the grinding is especially noteworthy in
the case of the grinding machine in question.
As already mentioned, the weight I serves only to balance frame B, and to
approach the object to the cylinder with a certain minimum pressure. But the
grinding pressure proper is exerted by a spiral spring r which is so arranged and so
influences frame B, that the grinding pressure is regulated automatically corre-
sponding to the shape of the piece of glass to be ground for the
purpose of obtaining
facets of equal width. For this purpose spring Figs. 1 & 3, is pushed over rod t
that is fastened to a bracket on the outside of stand C, and rests at its lower end on
a firm part of this rod.
go
The free end of the spring acts upon a yoke v which by means of its downwardly
extending portion v can be moved in the hollow portion of the rod t as shown in
Fig. 3. The yoke v is provided with a roller w which under influence of the spring r
is pressed against the circumference of a disc y, and thus presses the frame B or in
other words the object c against the grinding cylinder. This disc y rests on a shaft z
which rests in the frame B and is rotated by shaft e; the regulation of the grinding
pressure now is dependent exclusively upon the shape of disc y which corresponds
to the shape of the glass to be ground. If the latter for instance be round, a
round disc will be put up in the shaft and consequently a perfectly uniform
pressure will be exerted upon the plate of glass. If however facets of oval or other
non round forms are to be ground, the pressure disc y then used will be of a form
corresponding to that of the plate of glass. While this oval or other formed disc.
"

page_text: is being rotated, the spring will be alternately compressed and extended, and will
exert a correspondingly greater or smaller pressure.
2
If now the dise y which, as may be seen in Figure 3 of the drawing, like the
plate of glass, is supposed to be oval, it is so put upon the shaft that spring acts
upon it in the direction of its greater axis, while the plate of glass is being ground
in the direction of the smaller axis, the grinding pressure, in this position, will be
at its greatest, and, inversely, while the grinding is done in the direction of the
greater axis the grinding pressure will be at its lowest.
The strength of the grinding pressure is automatically regulated in reverse ratio
to the length of the axis at the place of grinding, and in this manner the production
of facets of uniform width is made possible.
In order to increase or diminish the grinding pressure in proportion to the
toughness of the material, rod t is threaded at its lower portion, and the tension of
spring can be more or less regulated by a nut t¹.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is--
1. The improvements in or connected with grinding machines or apparatus for
producing flat facets which consist in arranging in such machines or apparatus the
inclined object in almost horizontal position under a grinding cylinder and upon a
frame B rotated upon two horizontal pins ik for the purpose of changing the facet-
angle and arranging the object, the frame B being also movable in two directions
for the purpose of moving the object along the grinding cylinder and for the purpose
of fitting a machine for grinding glasses of very different sizes, and this frame
capable of being rotated about a vertical axis x for the purpose of moving it in and
out, substantially as described.
2. The combination with grinding machines of the kind mentioned in Claim 1, of
a mechanism to regulate the grinding pressure for the purpose of obtaining facets
of equal width, consisting of the arrangement of a disc y of a circular or other shape
and corresponding to that of the facet and fixed to the frame holding the object,
and which receives the pressure exerted by the spring r, and, according to its shape,
thereby making it perfectly uniform, and regulating it as necessary, substantially
as described.
Dated this 7th day of December 1892.
WM. P. THOMPSON & Co.,
Agents for the Applicant.