US2324374A - Apparatus for drilling diamonds and like purposes - Google Patents

Description

C. G. EDEN I July 13, 1943.

APPARATUS FOR DRILLING DIAMONDS AND LIKE PURPOSES Filed March 12, 1942 Inven'tor: Christophev G. Eden,

His A'btovneg Patented July 13, 1943 APPARATUS FOR DRILLING DIAMONDS AND LIKE PURPOSES Christopher G. Eden, Rickmansworth, England,

assignor to General Electric Company, a corporation of New York Application March 12; 1942, Serial No. 434,446 In Great Britain March 19, 1941 4 Claims.

diamond have to be separated from each other at intervals (generally considerably less than one second) in order that the diamond dust and oil with which the drill is supplied may reach the bottom of the hole; the required separation is usually less than 1 mm. and often less than 0.1 m. I

For the most satisfactory results the following conditions have to be fulfilled: (1) the extent of the separation is independent of the depth of the hole already drilled; (2) the separated parts, when they meet after separation, do so without excessive impact; (3) the ratio of the period of separation to the period of contact is readily variable; (4) the pressure of the drill on the diamond during drilling is constant.

An object of the invention is to provide simple means for attaining, or at least approaching very nearly, all of the said conditions. A machine for a purpose like diamond drilling means one in which the periodic separationof two parts by a distance less than 1 mm. and with a period less than 1 sec. has to be effected subject to conditions closely similar to those aforesaid.

In what follows it will be assumed for brevity that the bearings of the rotating drill are fixed and that the diamond carrier is moved by a driving member whose motion is completely determinate. It is permissible, though generally less desirable, to make any modification that leaves the relative motion of diamond and drill or tool unaltered; e. g., to fix the diamond carrier and move the drill. Any statement indicating the scope of the invention must be interpreted so as to admit of such modification.

According to the invention this object is achieved preferably by connecting the diamond carrier to the driver member through a hydraulic link and providing means whereby, during one part of the cycle, a connection is made between the fluid in the hydraulic link and a reservoir of fluid, so that, during this period, the drill and diamond come into contact whatever the position of the driving member.

The invention will now be explained further with reference to an embodiment, described by way of example and illustrated in the accompanying drawing by a partly sectional diagrammatic elevation.

Referring to the drawing, l is the diamond carrier or holder resting as usual on rollers 2, of

against the end of a horizontally disposed needle or drill (not shown). The hydraulic link consists of a. vessel 3 filled with liquid (usually oil) into which enter the pistons 4, 5. The outer end of piston 4, which is the driven member, is connected to the diamond carrier by a link 6, so that the motion of the carrier I in a horizontal direction is always the same as that of the piston 4.- Piston 5, which is the said driving member, is forced to enter and leave the cylinder by means of the straight cam I2 against which its outer end is pressed by the spring I. The cross section of the piston 4 is preferably (as shown) greater than that of the piston 5; but of course this is not necessary if the motion of 5 can be controlled suificiently finely.

If the vessel 3 were always closed during operation, the oscillations of the piston 5 would be reproduced in the motion of piston 4 (and thereforeof the carrier), on a scale reduced by the ratio of the cross section of piston 5 to that of piston 4. The carrier would oscillate between two fixed positions; once the drill had ceased to press on the diamond when the carrier was in its forward position, owing to the wear on either or both, drilling would cease. (Usually, of course, the drill wears much more rapidly than the diamond.)

In order that pressure between the drill and the diamond may be maintained, connection is made between the liquid in the vessel 3 and that in a constant-pressure reservoir 8 during (and only during) the period when the carrier is in its forward position and the driving member is at rest. The diamond is thus pressed against the drill during this period by a constant force; but since the connection to the reservoir is broken before the driving member moves, the excursion of the carrier produced by the driver does not depend on the position that the carrier takes up under the constant pressure.

The periodic making and breaking of the said connection is effected by causing the shaft 9 driving the cam to act as a tap in the tube I0, connecting the vessel 3 to the reservoir 8 in a. manner sufficiently indicated in the drawing.

In order that the part of the cycle during which the diamond and drill are separated may be readily varied, a link II' of easily variable length .s inserted in the connection between the cam l2 and the crank pin I3 driven by the shaft 9. Thus the link may consist in well-known manner of a sleeve l4 into which rods l5, l6, being screw-threads of opposite senses, work at which only the hindermost is shown, and pressed either end. It is thus possible to secure that the cam follower l1 moves between the points l8, [9 on the cam or between the points 20, 2| or over any intermediate range. In the first alternative, the period of separation is only that when the carrier is moving; in the second, the period of separation is substantially the whole cycle; in the third it may be anything between these extremes.

The velocity with which the carrier approaches the drill in its forward position may be made very small by shaping the cam surface suitably. All possibility of impact under the influence of the driving member may be thus avoided. Objectionable impact under the constant pressure in reservoir 8 is highly improbable, since the amplitude of the motion under this pressure will always be very small. Roughly speaking, it cannot be greater than the amount by which the depth of the hole was increased during the drilling period preceding the last separation. But impact can always be avoided by providing sufllcient resistance to the flow of liquid between the reservoir 8 and the vessel 3.

In an alternative embodiment the piston 4 itself is used as the diamondcarrier, the diamond being mounted on the outer end of it.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In apparatus of the class described, the com-' bination of a driven member, driver mechanism for urging said driven member forward in a given direction and periodically retracting it a short distance, and hydraulic link mechanism connecting said driven member to said driver' mechanism and providing means for periodically supplying a constant pressure to the fluid in said link mechanism only when the driven member is in its forward position and the said driver mechanism is at rest so that the driven member is then urged forward by a force determined by the said constant pressure means.

2. In apparatus for drilling diamonds and like purposes, the combination of a work holder, driver mechanism for urging said work holder forward in a given direction against a drill and periodically retracting it a definite short distance which is independent of the depth of the hole already drilled, and means, independent of said driver mechanism, for periodically applying a deflnite constant force to said work holder only during the period it is in its forward position and the said driver mechanism is at rest so that the work holder contacts the drill with a definite pressure regardless of the position of the driver mechanism.

3. In apparatus of the class described, the combination of a driven member, driver mechanism for urging said driven member forward in a given direction and periodically retracting it a definite short distance, hydraulic link mechanism connecting said driven member to said driver mechanism, a constant-pressure fluid reservoir, and means for periodically connecting the fluid in said link mechanism with said reservoir only durng the period when said driven member is in its forward position and the said driver mechanism is at rest so that the said driven member is urged forward during the said period by a force determined by the pressure in said reservoir.

4. In apparatus of the class described, the combination of a driven member, a driving member, a hydraulic link connecting said driven and driving members, cam means engaging said driving member to urge said driven member forward, through said hydraulic link, and to retract it a definite short distance, a constant-pressure fluid reservoir, a conduit connecting said reservoir with the fluid in said hydraulic link, valve means forming part of said conduit, said valve means being connected to said cam means, and said valve means and cam means being so constructed and arranged that the valve means periodically connects the fluid in said link with said reservoir only during the period when said driven member is in its forward position and the driving member is at rest so that the said driven member is urged forward during this period by a force determined by the pressure in said reservoir.

- CHRISTOPHER G. EDEN.

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