Improvements in Machinery or Apparatus for Grinding and Polishing Lenses.
Year: 1892

page_text: Date of Application, 15th July, 1892-Accepted, 1st Apr., 1893
COMPLETE SPECIFICATION.
Improvements in Machinery or Apparatus for Grinding and
Polishing Lenses.
I, THOMAS BOURNE of 76 Stour Street, Birmingham, in the County of
Warwick, Glass Beveller and Merchant, 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 :-
Owing to the considerable cost of grinding and polishing by the means ordinarily
employed, lenses suitable for use in lamps and lanterns to diffuse light it has been
customary to employ to a large extent lenses cast in moulds.
Now this invention has reference to the construction of machinery or apparatus
whereby sheets or blocks of plate glass may be readily, accurately and economically
formed into lenses by grinding and polishing.
For this purpose in a machine according to my invention the glass to be operated
upon, and which, before being placed into the machine, has had a circular form
imparted to it, is secured to a shaft or spindle that holds the glass with its exposed
face in contact with an annular grinding and polishing surface to which motion
in a rotary sense is imparted at the same time that the said spindle or shaft receives
motion not only in a rotary sense about its own axis but also in an oscillatory sense
so that the desired convex form is imparted by the grinding and polishing surface
to the surface of the circular piece of glass under treatment, as I will now proceed
to more particularly explain by aid of the accompanying illustrative drawings,
which illustrate in three several modifications the construction of machinery or
apparatus according to my invention.
Referring to these drawings
Fig. 1 is a part sectional elevation of a machine.
Fig. 2 is a part plan of the same, and
Fig. 3 is an end view.
1 is an ordinary head-stock with cone pullies 2 and face plate 3, which carries a
ring 4 whose inner circumference constitutes an annular grinding surface. As will
be seen this ring can be readily removed from the face plate 3.
The glass disc to be operated upon is arranged to bear upon the internal surface
of the ring 4, the radius of said internal surface being made to correspond to the
radius of the curvature to be given to the lens. The ring 4 is formed of or lined
with or has applied thereto suitable grinding or polishing material according as the
lens is to be ground or polished. Suitable materials are, for grinding, sand or
emery with water, and for polishing, putty powder, rouge, fuller's earth, or
5 powdered pumice stone, that is to say materials such as are commonly employed
for grinding & polishing glass. Several rings of different kinds may be provided
so that grinding and polishing can be effected successively in the same machine.
The glass disc 5 to be operated upon is attached by means of a layer of pitch
or other adhesive medium to the under side of a disc 6 which is provided with a
O spindle 7 extending into a hollow shaft & mounted in journals 9 carried as shewn in
Fig. 1 in the fork shaped end of an arm 10, the other end of which is pivotally
connected to a bifurcated head at the end of a rocking shaft 11 carried by a fixed
standard 12.
On the hollow shaft 8 which is connected with the disc 6 by means of a pin 13
5 fixed thereon and taking into a recess in the shaft 8, is keyed a worm wheel 14
driven by a worm 15 fixed on shaft 16 mounted in bearings on the arm 10 and
driven from a cord pulley 17. The arm 10 is connected with the shaft 11 by
means of conical ended screw threaded studs 18 which pass through correspondingly
screw threaded holes formed in the cheeks 19 of the head of the shaft 11 and take

page_text: into conical recesses formed on opposite sides of that end of the arm 10 which is
not fork shaped. By this arrangement, the arm 10 can be swung back as indicated
in dotted lines (Fig. 1) to facilitate the changing of lenses. For the purpose of
enabling lenses of different contours and thicknesses to be produced a series of
holes are formed in the cheek,19 so that the fulcrum of the arm 10 can be raised
or lowered as desired. To allow of a rocking motion being imparted to the arm 10
and so to the glass disc being operated upon there is fixed to the bifurcated head
of the shaft 11 a lug or projection 20 to which is pivoted a rod 21 connected to a
crank or eccentric 22 which receives motion through the medium of a worm
wheel 23 and worm 24 from a cord pulley 25.
Fig. 4 is a side elevation on a reduced scale shewing so much as is necessary to
illustrate a modification of the machine in which the glass disc bears upon the
periphery of a disc, the glass disc being arranged as hereinabove described with
reference to Figs. 1, 2 and 3 in connexion with a spindle that is rotated and rocked
.as set forth.
Fig. 5 is a part sectional elevation to a larger scale illustrating a further
modification in which the glass disc is caused to bear upon a rotating table, the
upper surface of which is grooved as shewn at 26, the rotating and rocking motion
being imparted to the spindle that carries the glass disc as described with reference
to Figs. 1, 2 and 3,
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
:-
1. A machine for grinding and polishing lenses comprising an annular grinding
or polishing surface and means for holding the glass to be operated upon and for
imparting thereto motion in a rotary sense simultaneously with an oscillatory or
rocking motion as set forth.
2. In a machine for grinding and polishing lenses an annular grinding or polishing
surface formed on the interior of a ring the said surface being curved to a radius
corresponding to that of the convexity to be imparted to the lens.
3. In a machine for grinding and polishing lenses the combination of parts
constructed arranged and operating substantially as described for the purpose of
holding the glass to be operated upon and imparting thereto motion in a rotary
sense about its axis simultaneously with an oscillatory or rocking motion.
4. The construction of machines for grinding and polishing lenses as hereinabove
described with reference to Figs. 1 to 3 inclusive, or modified according to Fig. 4
or to Fig. 5 of the accompanying drawings.
Dated this 15th day of July 1892.
W. LLOYD WISE,
Per F. J. Broughan,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.