US3440770A

US3440770A - Device for polishing specimens

Info

Publication number: US3440770A
Application number: US612997A
Authority: US
Inventors: Jacques Klein; Bernard Mansard
Original assignee: Commissariat a lEnergie Atomique CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 1966-02-18
Filing date: 1967-01-31
Publication date: 1969-04-29
Anticipated expiration: 1986-04-29
Also published as: FR1475016A; NL6702127A; CH472267A; BE693093A; GB1102738A; LU52970A1; ES336563A1

Description

April 29, 1969 J, KLElN ET AL 3,440,770

DEVICE FOR POLISHING SPECIMENS Filed. Jan. 31, 1967 Sheet of 2 FIGI April 29, 1969 J. KLEIN ETAL DEVICE FOR POLISHING SPECIMENS Filed Jan. 31, 1967 United States Patent "ice Int. Cl. 1324b /04 U.S. Cl. 51-129 4 Claims ABSTRACT OF THE DISCLOSURE The polishing device comprises a rotary disc covered with abrasive. The specimens are each retained and driven in rotation by a wheel rotatably mounted on a stationary plate, the wheels being in frictionally driven contact With a cone which is concentric with the rotary polishing disc.

This invention is directed to a device for polishing specimens and is more specifically concerned with polishing devices of the type comprising a rotary polishing disc having a flat abrasive face at right angles to its axis of rotation and comprising a substantially cylindrical plate for retaining specimens to be polished.

Uniform polishing of specimens on a rotating wheel or disc is ensured by subjecting the specimens to a movement of rotation about their own axes in order to compensate for differences in linear velocities of the polishing wheel at the different points of the surface to be polished. In order to utilize this inequality of velocities at different points of contact and the resultant application on the specimen of a force which is displaced with respect to the center of its contact sulface, the majority of devices which are in service at the present time accordingly impart a movement of rotation to the specimen. In point of fact, the movements of rotation which are thus obtained are not usually uniform and, in addition, there is not even any guarantee that the specimen will be set in rotation,

The present invention is directed to the design concept of a polishing device which meets practical requirements more effectively than comparable devices of the prior art, especially insofar as it ensures a uniform movement of rotation of the specimen without any attendant danger of jamming, this result being achieved only by the use of simple mechanisms which do not interfere with the positioning and removal of specimens. The point last mentioned is important since such operations are frequently carried out by means of manipulators, particularly when the work involves handling of radioactive specimens in hot laboratories.

To this end, the invention proposes a device fitted with a mechanism for driving specimens in rotation, said mechanism comprising at least one wheel which is driven in rotation by the polishing disc about an axis which is parallel to that of said disc, said wheel being placed with respect to a specimen-insertion hole formed in the plate in such a manner that the frictional contact of the polishing disc with the specimen moves this latter against the wheel.

In a preferred embodiment of the invention, the mechanism also comprises a roller which is mounted to rotate freely on said plate on a spindle which is parallel to the spindle of the driving wheel, the roller being placed with respect to the wheel in such a manner that the specimen is applied both against said wheel and said roller.

The direction of rotation of the driving wheel and the position of said wheel with respect to the hole are advantageously chosen so that the action of the wheel is 3,440,770 Patented Apr. 29, 1969 added to the action of the difference in linear frictional velocities at the different points of the specimen so as to cooperate in setting this latter in rotation.

The invention further consists in other arrangements which are preferably employed in conjunction With the preceding but which can be employed independently. All of these arrangements will become more readily apparent from a perusal of the following description of a preferred embodiment of the invention which is given by way of non-limitative example, reference being bad to the accompanying drawings, in which:

FIG. 1 is a view in elevation of the device with a specimen to be polished in position;

FIG. 2 shows the device looking on the right-hand side of FIG. 1, the specimen-holding plate and drive mechanism being in the raised position.

The device which is illustrated in FIGS. 1 and 2 comprises a horizontal base-plate 4 which carries a drive motor (not shown in the drawings). Said motor is adapted to drive in rotation in the direction of the arrow 1 a vertical shaft 6 which carries a rotary polishing disc 8; the top face of the disc is provided with a flat covering 10 of abrasive.

Bearing-brackets 12 are mounted on the base-plate 4 and fitted with a horizontal pin 14 on which is pivotally mounted a swingable unit generally designated by the reference 15; said unit 15 is made up of a plate 16 for receiving and retaining specimens and an arm 18 which is pivotally mounted on the pin 14. The arm and plate are secured to each other by any suitable means such as screws 20 and shims (not shown) which can be interposed between said arm and said plate so as to modify the relative positions of these latter and to ensure that the plane of the specimen retaining plate and the plane of the base-plate are in parallel relation.

The plate 16 of the device which is illustrated in FIGS. 1 and 2 is pierced by three circular holes such as the hole 22 for the purpose of accommodating specimens such as the specimen 24. As shown in FIG. 2, the holes 22 have a diameter which is slightly larger than that of the specimens in order to permit of a certain freedom of motion in plan when the specimen retaining plate is in the lowered position.

The mechanism for driving the specimens in rotation is provided with portions which are associated with each of three holes and a common portion. Said common portion comprises a driving cone 26 which is rotatably mounted on a spindle 28, said spindle being fixed at the center of the specimen retaining plate 16 by means of a nut 29. When the specimen retaining plate is lowered to the operating position, the driving cone moves into position in coaxial relation with the rotary polishing disc, thereby constituting a stationary abutment which fixes the height of the specimen retaining plate 16 above the abrasive covering 10. In addition, said cone 26 is adapted to be driven in rotation by the polishing disc. For this purpose, a blind-end slot of elongated shape is formed in the large base of the cone so as to engage over a tenon 30 of corresponding shape which is formed in the line of extension of the drive shaft 6.

A driving wheel 32 is associated with the hole 22 and is mounted on a spindle 34 which is secured to the specimen retaining plate. The wheel is mounted to rotate freely on the spindle 34 and is additionally capable of slidingly longitudinally along said spindle for the purpose of ensuring that a rubber rim 36 which is fitted on said Wheel is brought to bear against the cone 26 under the action of the weight proper of the wheel. Thus, when the cone, which is driven by the polishing disc, rotates in the direction of the arrow 1, the wheel 32 rotates in the opposite direction (arrow j in FIG. 2).

The driving wheel 32 is placed with respect to the hole 22 in such a manner and has a diameter such that it projects slightly within said hole 22; as shown in FIG. 2, said wheel is located downstream of the hole in the direction of rotation f of the polishing disc and the wheel spindle 34 is slightly nearer the center of the polishing disc than the center of the hole 22.

That portion of the drive mechanism which is associated with the hole 22 further comprises a guide roller 38 which is rotatably mounted on a vertical spindle 40 which is also secured to the specimen retaining plate 16. Said roller is also placed downstream of the hole 22 in the direction of rotation of the polishing disc and radially so as to project also within the hole, the axis of said roller being located at a slightly greater distance from the center of the polishing disc 8 than the center of the hole 22.

The operation of the device is apparent from the foregoing description and will therefore be described only briefly. When the unit is in the lowered position, the specimen to be polished is inserted through the hole 22 and placed in position on the polishing disc. As soon as the disc is set in rotation, the specimen 24 is drawn into abutment against the wheel 32 and the roller 38. The wheel 32 then drives the specimen in rotation in the direction indicated by the arrow 1 in FIG. 2, that is to say in the direction of rotation of the polishing disc 8. Thus, the effect produced by the difference in linear velocities of the polishing disc at the different points of contact is added to the action of the wheel 32.

It can therefore be seen that, although the specimen is not subjected to any mechanical connection and no stresses arise other than those which are exerted on the polishing disc by the sample itself under the action of its own Weight (to which a suitable ballast-weight may be added), said specimen performs a movement of rotation about its own axis at a constant speed which ensures uniform polishing.

The device which is illustrated in FIGS. 1 and 2 is designed to receive three specimens although any number may be provided. In fact, the number of specimens is limited in practice solely by the dimensions of the polishing disc. It is noted in addition that the positioning and removal of specimens remain extremely simple operations both during rotation and when the device is stationary and the tolerance allowed on the diameter of specimens is as great as was the case in devices of the prior art.

A large number of alternative modes of construction can of course be contemplated. It must be understood that these alternative forms as well as any others which remain within the scope of equivalent mechanical means are covered by this patent.

What we claim is:

1. A device for polishing specimens of substantially cylindrical shape wherein said device comprises a rotary polishing disc having a fiat abrasive face at right angles to its axis of rotation and a mechanism for retaining and driving specimens in rotation, said mechanism comprising at least one roller which is mounted to rotate freely on a spindle which is parallel to the drive shaft of the polishing disc and a wheel which is mounted to rotate freely on a spindle which is substantially parallel to the drive shaft of said polishing disc, said wheel being applied against and driven by a cone which is coaxial with the polishing disc and which is disengageably coupled for rotation with said disc, the position of the roller and of the wheel being such that the friction between the polishing disc and a specimen causes said specimen to be applied against said roller and against said Wheel.

2. A polishing device in accordance with claim 1, wherein the wheel is slidably mounted on a spindle carried by a plate and is applied against the driving cone under the action of its own Weight.

3. A polishing device in accordance with claim 1, wherein said device comprises a plurality of pairs of wheel and roller assemblies which are uniformly spaced around the driving cone and each adapted to drive a specimen.

4. A polishing device in accordance with claim 3, wherein the driving cone, wheels and rollers are rotatably mounted on a plate which is swingably mounted on a pivot-pin located at right angles to the axis of the polishing disc and the downward application of the cone against the polishing disc fixes the operating position of the plate in which openings are pierced for accommodating specimens.

References Cited UNITED STATES PATENTS LESTER M. SWINGLE, Primary Examiner.