US2819569A

US2819569A - Automatic abrasive liquid distributing device for optical lens polishing machines

Info

Publication number: US2819569A
Application number: US490350A
Authority: US
Inventors: Angenieux Pierre
Original assignee: Pierre Angenieux SA
Current assignee: Pierre Angenieux SA
Priority date: 1954-07-28
Filing date: 1955-02-24
Publication date: 1958-01-14
Anticipated expiration: 1975-01-14

Description

Jan. 14, 1958 P. ANGENIEUX 2,819,569

' AUTOMATIC ABRASIVE LIQUID DISTRIBUTING DEVICE FOR OPTICAL LENS POLISHING MACHINES Filed Feb. 24, 1955 2 Sheets-Sheet l Mn uentor:

j ferre, flngenieux 7 M 5. muw

Jan. 14, 1958 P. ANGENIEUX 2,319,569

AUTOMATIC ABRASIVE LIQUID DISTRIBUTING DEVICE FOR OPTICAL LENS POLISHING MACHINES Filed Feb. 24, 1955 2 Sheets-Sheet 2 $1 8 l'l'e nnyenfeu V 1am I. 9711' Km United States AUTOMATIC ABRASIVE LIQUID DISTRIBUTING DEVICISl FOR OPTICAL LENS POLISHING MA- CHINE Pierre Angenieux, Paris, France, assi'gnor to Etablissements Pierre Angenieux (Societe a Responsabilite Limitee), Paris, France, a corporation This invention relates to machines for polishing optical lenses and more particularly to a device for automatically distributing an abrasive, liquid in machines of the type comprising a concave part-spherical member and a convex part-spherical member contacting each other, one of these members consisting of the optical surfaces to be polished and the other of the polishing tool proper, both members being imparted an adequate relative movement with respect to each other.

It is known that the abrasive liquid employed in machines of this type consists of a pulverulent abrasive, generally a metal oxide, preferably a rare metal oxide, in suspension in a liquid medium such as water. As a substitute for manual distribution, it has already been proposed to provide a continuous feed of the abrasive liquid, but experience proved that it was hardly possible to obtain and maintain a homogeneous and uniform film all over the surface of the polishing tool. Briefly, the abrasive powder distribution and film thickness vary from the point of impingement of the abrasive liquid to the point remotest therefrom. Moreover, this solution is extremely costly in that it involves an important consumption of the abrasive product. The recovery of the liquid implies a closed-circuit operation with all the detrimental consequences resulting from the pollution of the liquid by many foreign substances deriving partly from the abrasion work proper.

It is the essential object of this invention to provide an intermittently operating automatic abrasive liquid distributing device designed to avoid the inconveniences broadly set forth hereinabove.

According to this invention the device comprises a closed-circuit arrangement in which the abrasive liquid is caused to flow with a relatively large output, the relatively small amount of liquid required for treating the common contact surfaces of the co-acting part-spherical members being taken automatically and intermittently from this circuit and distributed inbetween these co-acting surfaces, the installation being adapted to supply a plurality of polishing machines.

The attached drawings forming part of this specification illustrate diagrammatically by way of example one form of embodiment of the device constructed in accordance with the teachings of this invention.

In the drawings:

Figure 1 is a comprehensive, part-sectional view of the device;

Figure 2 is an elevational sectional view of the electromagnet valve effecting the intermittent distribution of the abrasive liquid;

Figure 3 is a part-sectional, fragmentary view of a detail variant.

In Fig. 1 of the drawings; 1 is the concave part-spherical member acting as a polishing tool, which rests on the lenses 2 to be polished, the latter constituting together the convex part-spherical member and being secured on a support 3 to which a combined rotational and oscillating motion about the common centre of both members may be impressed, according to the known technique. The concave member I is held by a tubular rod 4 formed with a substantially spherical end portion 5 and suitably guided in vertical guiding means (not shown) and engaging a cavity 6 formed in the aforesaid concave member to form a ball-and-socket coupling.

According to this invention the liquid distributing device comprises a reservoir 7 containing the liquid to be distributed 8, which consists for example of cerium oxide particles in suspension in a suitable liquid, for example water. A centrifugal pump 9 driven from a motor 10 forcesthis liquid through pipings 1 1, 12, 13, 14, 15 and 16; the pipe sections 14 to 16 ensuring the return flow to the reservoir 7, as shown. This liquid circulation occurs with a large output to maintain the oxide particles in suspension in the liquid medium. The flow occurs in closedcircuit fashion through

valves

17 and 13; the number of these valves is equal to that of the polishing stations to be supplied with abrasive liquid through the pipe portion 13. In Fig. l the valve 17 shown in vertical section overlies the part-spherical members 1, 2, whereas the other polishing station corresponding to the valve 18 is not shown.

As illustrated in the drawing the valve 17 comprisesa chamber 19 connected to the pipe 13 and having formed in its bottom wall a port 20 normally closed by a needle valve 21, of the needle type regularly and intermittently raised to its open position to allow a few drops of abrasive liquid to flow through the port 20; These drops are received in a funnel-shaped member 22 mounted on top of the tubular rod 4 holding the concave member 1, and a duct 23 coaxial with the rod 4 directs the drops into the space formed between the two part-spherical members to wet by capillarity and centrifugal action the concave surface of the polishing tool 1 (both part-spherical members being driven for rotation during the polishing operation, whilst the holding rod 4 is stationary).

Reference will now be made to Fig. 2 showing the constructional details of a valve and its operation.

This valve is of the electromagnetically controlled type. To avoid the formation of oxide deposits the port 20 of the valve chamber should be as close as possible to the liquid stream, as shown in the drawing. The upward movement of the needle valve 21 is controlled through an electromagnet coil 24 which, when energized, attracts the armature 25 rigid with the valve member 21. When the electric pulse is terminated a spring 26 returns the valve member 21 to its seated position to close the port 20. The stroke of the needle valve 21 is a function of the gap d between the valve armature 25 and the coil core 27. This gap may be adjusted by removing the cover member 28 from the valve body 17 to which the coil is attached by nuts 29. To ensure the fluid-tight closing of the port 20 the end or operative portion 30 of the needle valve 21 is made of rubber or like resilient material.

The energizing impulses are fed to the coil 24 from a so-called microswitch device 31 controlled by a cam disc 32 rotatably driven from a slow-running motor (not shown). Current flows through the circuit connecting the microswitch 31 to the winding 24 each time the notch 33 formed in the cam disc 32 moves past the actuating pin 34 of the microswitch. A suitable frequency of operation of the microswitch 31 is of the order of one impulse per minute. A main switch 35 is provided to short-circuit the microswitch 31 when it is desired to effect a supply of abrasive liquid at any time.

The device illustrated in Fig. 3 is designed for those cases wherein it is desired to polish a separate concave lens, in this case, the lens constitutes the concave partspherical member and the polishing tool 38 constitutes the convex part-spherical member of the assembly. Under these conditions, a funnel-shaped member 22 is also pro-y Patented Jan. 14, 1958 3 vided for collecting the drops of abrasive liquid, but the holding rod 4 is not tubular but solid, the axial aperture being replaced by a lateral pipe section 39 conducting the liquid from the bottom portion of the funnel 22, clear of the lens, to the convex surface of the polishing tool.

Of course, if the upper concave member holding rod were oscillated instead of being stationary, the device would operate in the same manner but a flexible hose connection or the like should be provided between the value port 20 and the funnel 22.

What I claim as new is:

1. Lens polishing machine comprising a concave upper spherical member acting as a polishing device and a convex spherical member consisting of the optical surfaces, sa-id concave spherical member bearing on said convex spherical member and being held by a stud occupying thereabove a fixed vertical position, the geometrical axis of said stud passing through the common centre of said spherical members, said concave spherical member being adapted to rotate freely about said geometrical axis, said stud comprising an axial duct having an extension passing through the top of said upper spherical member so as to open inbetween said concave and convex spherical members, a funnel disposed at the upper end of said duct, and means for feeding said funnel with the abrasive liquid to be distributed over the contact surface of said spherical members.

2. Lens polishing machine as set forth in claim 1, wherein said means for feeding said funnel with abrasive liquid comprise a closed circuit in which a relatively large output of abrasive liquid is circulated continuously, said closed circuit having inserted therein a distributor comprising a body provided with an abrasive-liquid distributing orifice positioned vertically above said funnel, a valve member adapted to obturate said orifice, and control means for periodically unseating said valve member to allow a small amount of abrasive liquid to flow directly into said funnel.

3. Lens polishing machine as set forth in claim 1, wherein said means for feeding said funnel with abrasive liquid comprise a closed circuit in which a relatively large output of abrasive liquid is circulated, said closed circuit having inserted therein a distributor comprising a body provided with an abrasive-liquid distributing orifice, a valve member adapted to obturate said orifice, control means for periodically unseating said valve member to allow a small amount of abrasive liquid through said orifice, and a flexible hose connecting said orifice with said funnel.

References Cited in the file of this patent UNITED STATES PATENTS 1,409,888 Taylor Mar. 14, 1922 1,513,813 Hill et a1. Nov. 4, 1924 1,619,344 Hill Mar. 1, 1927 1,620,021 Hitchcock Mar. 8, 1927 1,625,197 Eisenhauer Apr. 19, 1927 1,800,743 Morris Apr. 14, 1931 2,069,261 Cassity Feb. 2, 1937 FOREIGN PATENTS 215,661 Great Britain May 15, 1924