IN APPARATUS FOR GRINDING OVAL GLASSES, MIRRORS AND SUCH LIKE
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Edwin Ambrose Brydges at the Office
of the Commissioners of Patents on the 16th December 1882. Communicated
to him by the firm of Schwarz Brothers of the Town of Fürth in the Kingdom
of Bavaria and German Empire.
te
EDWIN AMBROSE BRYDGES of the firm of "Brydges & Co" Engineers and Patent
Solicitors of 107 Königgrätzer Str in the City of Berlin and German Empire and
IMPROVEMENTS
of 6 St. Leonards Terrace Upton in the County of Middlesex.
IN APPARATUS FOR GRINDING OVAL GLASSES, MIRRORS AND SUCH LIKE." a
communication to me by the firm of Schwarz Brothers of the Town of Fürth in
the Kingdom of Bavaria and German Empire.
This Invention relates to improvements in apparatus for grinding oval glasses,
mirrors and such like other objects which are given an oval or round form.
The shaft or axle of the apparatus is carried in suitable bearings in the frame
and is caused to rotate by means of a strap and strap drum. This shaft or axle
passes through a guide disc which said guide disc can be adjusted laterally between
suitable guides and can be rigidly attached to the axle or shaft by means of
suitable screws
On the said shaft in front of the guide disc is a face plate which said face plate
is provided with two slots in which said slots the rods or bolts are moveably
arranged. These said rods or bolts are firmly attached to or screwed into the slide
which moves in suitable guides on the face plate. Each two of such said rods or
bolts are connected at the end opposite to the face plate to each other by means of
a connecting piece of metal or rod which by each rotation of the disc, when such
said disc occupies an excentrical position, move or slide on the same and transmit
their movement to the face plate which said face plate rotates with like speed to
the disc.
The shaft or spindle attached to the slide makes an elliptical movement which
said movement is also transmitted to the elliptical disc on the shaft or spindle
which said shaft or spindle also carries the mirror or other matter which is to be
ground into oval or other suitable form. The above described mechanism for
obtaining an elliptical movement of the object to be operated on is the well known
oval mechanism.

page_text: In order to provide the object to be ground with a good bearing a sheet of
india rubber, felt or other elastic material is attached to the disc which said disc is
further provided with a rim of brass or other suitable material in order to prevent
the mirror or other object to be ground from leaving its position. The mirror or
other object to be operated on is further held in position by means of a disc or
plate the surface of. which is covered with india rubber or other suitable material in
order to prevent the surface of the mirror or other object from being scratched or
injured. This said plate or disc is held in position by means of an adjustable
spring the forward end of which said spring is provided with a pivot peg or pin
which said pivot or pin is pointed and fits into a suitable cavity or recess in the
rear surface of the plate or disc; or the pin or pivot can be attached to the rear
surface of the plate or disc and fit into a suitable cavity or recess in the end of the
spring. It is necessary that the device be self adjusting in order to prevent the
mirror or other object from leaving its position and for this reason the parts are so
arranged that the spring and plate or disc follow the movement of the glass mirror
or other object in such manuer that the disc or plate constantly remains in the
centre of the ellipse.
This device or arrangement consists of a slide which is in connection with the
spring and the axle or spindle which latter possesses an elliptical movement.
A spindle axle or shaft is carried in suitable bearings in the frame of the
machine and carries a slide box. A slide is so arranged in this said slide box that
the said slide can move up and down and at the same time make an oscillating
movement. The oscillating movement is effected by means of a connecting rod.
which is arranged around the shaft. By means of the connecting rod the
elliptical movement of the shaft is transmitted to the slide which is thereby moved
backwards and forwards.
The slide also guides the spring which is connected to the said slide by the rod
so that the spring receives a like motion to the shaft. The slide box is moveably
attached to the shaft and permits the vertical movement of the slide in suitable
slots. This movement is applied in order to compensate for the slight vertical
movement of the plate or disc in rotating by means of the spring which as
aforenamed is in connection with the slide.
The grindstone, of stone, stone and iron or other suitable material is arranged to
carry out the preliminary coarse and fine grinding of the glass, mirror or other
object. The polishing can be effected by replacing the grindstone by a disc of
wood or other suitable polishing material."
The grindstone is attached to a shaft which is carried in suitable bearings in
the frame and receives its rotary motion by means of a strap. drum or suitable
gearing.
The shaft and also the grinding stone can be moved in the horizontal plane in
order to prevent the stone from being subjected to undue wear and tear at one
point.
In order to attain an equable wear and tear of the entire surface of the stone the
following arrangement is employed.
A ring collar or cylinder provided with a cam groove is placed on a fixed axle
or spindle in the frame which said cylinder with cam groove is connected to a
strap drum.
A two armed lever which can make a partial revolution around a pivot or stud
is guided at the lower end in the cam groove whereas the upper arm is arranged
between two rings or collars on the shaft.
The cam is rotated by means of the strap drum on the shaft which said drum is
so connected to the second strap drum by means of a suitable strap that the second
drum and cam are caused to rotate with the said drum. As the cam rotates the
lever guides the shaft, and consequently the stone to the right or left as the case.
may be.
In order to be able to stop the action of the shaft and remove the mirror or
other object from contact with the stone a level which turns on a suitable centre

page_text: is arranged at the opposite end of the shaft to that carrying the oval grinding
devices. If the free arm of the hand lever is now moved to the right, the upper
lever arm will be moved in an opposite direction and the shaft and the devices
connected to the same moved to the left and thus withdrawn from contact with
the stone.
A third arm is firmly connected to or made of one piece with the said hand lever
to the outer end of which said arm is attached the one end of a spiral spring the
other end of which said spring is fixed or attached to a suitable frame.
This spring serves to continuously press the mirror or other object into contact
with the grind stone as the tension of this spring draws the outer lever arm
upwards and presses the upper arm of the lever the shaft and the devices attached
to the same to the right hand and as aforesaid in contact with the stone.
Instead of using the spiral spring a suitable weight can be employed.
It is also evident that the position of the parts can be varied in many ways and
the parts themselves modified without departing from the tenor of this said
invention..