US2413678A - Work-holding means for grinding machines - Google Patents

Description

7, 1947. R. s. BEVERLIN 2,413,678

WORK-HOLDING MEANS FOR GRINDING MACHINES Filed July 19, 1945 2 Sheets-Shed; 1

E 02171;? 5. BEVERLIN Jan. 7, 1947. R. s. BE'VERLIN 2,413,678

' WORK-HOLDING MEANS FOR GRINDING MACHINES Filed July 19, 1945 2 Sheets-Sheet? 4 V :7; I 4L 41 HUB RT 5. BBYERLIN Patented Jan. 7, 1947 WORK-HOLDING MEANS FOR GRINDING MACHINES Robert S. Beverlin,

Aerodynamic Research ton, D. 0., a corporation of the District of Columbia Toledo, Ohio, assignor to Corporation, Washing- Application July 19, 1945, Serial No. 605,993

2 Claims.

This invention relates to work-holding means, and is illustrated in connection with a grinding machine to hold a Valve in position for grinding or refacing.

An object of .the invention is the provision of a work-holding fluid operated means of simple and efficient construction that is quickly operable to engage or release a work-piece, such, for instance, as the stem of a tappet Valve, and to firmly hold the engaged work-piece in position to be acted on whereby to enhance the practicability and operating efficiency of the device.

Further objects and advantages of the invention will be apparent from the following detailed description, and from the accompanying drawings, in which- Fig. l is a perspective view of a valve refacing machine embodying the invention; Fig. 2 is a central vertical longitudinal section of the workholding and rotating means of the machine, with the collet contracted and holding a work-piece; Fig. 3 is an enlarged perspective detail of one of the sleeve members of the work-holding means; Fig. 4 is an enlarged perspective view of the chuck sleeve; Fig. 5 is an enlarged perspective view of the removable front end portion of such sleeve; Fig. 6 is an enlarged perspective view of the clip for securing the two chuck sleeve sections in assembled relation; Fig. '1 is a perspective view, in expanded form, of a collet used in connection with the device, and Fig. 8 is a fragmentary section similar to Fig. 2, with the chuck sleeve retracted and .the collet in expanded position.

In the drawings, l9 designates a frame head having, in the present instance, a horizontal bore I l in which a sleeve I2 is rotatably mounted with both ends projecting from the bore. This sleeve is prevented from endwise movements in the head in any suitable manner, which in the present instance includes a radial flange I3 thereon projecting into an end and engaging the inner wall thereof. The outer or free end of the sleeve receives a work-holding collet 11 for radial expanding and contracting movements therein and with its outer end bearing against a conically restricted end portion l8 of the sleeve for collet centering and contracting purposes, as understood in the art.

In the rear end portion of the sleeve I2 is mounted a longitudinally slidable chuck sleeve 20 having a separable nose portion 2| with the outer end of its bore provided with an internal conical taper 22 for coaction with the inner or rear end of the collet in opposition to the restriction 18 to eflect contraction of the collet when the sleeve recess M in the head bore 29 is moved forward. In the present instance, the sleeve 20 and its separable nose piece are releasably secured together by a spring clip 23 having outwardly projecting radial edge lips engaging in internal recesses in the sleeve sections. The rear end of the sleeve 20 is longitudinally forked as shown in Fig. 4, thus forming an annular series of alternate recesses 24 and fingers 25, the fingers terminating at their outer ends in stepped shoulders 26 for the purpose hereinafter described.

Mounted in the rear end portion of the sleeve 29 and projecting rearwardly therefrom is a sleeve 21 shown in detail in Fig. 3, which has an annular flange 28 intermediate its ends with lengthwise extending openings 29 in its base portion through which the sleeve fingers 25 project for free longitudinal movements. The sleeve 21, immediately forward of the flange 28, is provided with segmental projections 39 extending through the registering recesses 24 of the sleeve 20 and threading at their outer ends to the rear inner end portion of the drive sleeve 12, as shown at 31 in Fig. 8. The two sleeves l2 and 21 are locked together in threaded engagement by a set-screw 32 threaded into a radial socket 32' in the flange 28 and engaging an end notch in the sleeve I2. For this purpose the base portion of the flange 28 is recessed as shown at 33 in Fig. 3, so that it partially overhangs the sleeve end. It is thus apparent that the sleeves I2, 20 and 21 turn together with the sleeves l2 and 21 locked against relative movements and with the sleeve 20 adapted to have limited longitudinal movements relative thereto.

A pulley 35 end of the sleeve part of the head is fixedly mounted on the rear 12 between the sleeve bearing l9 and the flange 28. In the present instance, the pulley 35 has connection with and is driven by a motor 35 which also serves to drive the grinding wheel 31 of the machine.

Threaded on the rear end of the sleeve 21 is an end flange 38, and connecting this and the flange 28 with its respective ends shouldered thereon for relative turning movements is a cylinder member 39 concentric to the axis of the sleeve 21 and forming the outer wall of a cylindrical chamber 40 around said sleeve. This member is secured against turning relative to the frame head H) by a pin 4| projecting from an arm 42 on the member into a hole 43 in said head.

The chamber 40 is made fluid-tight at its rear or outer end by a ring 44 fitted in the member 39 and fixedly mounted on the sleeve 21 between a spring-looking ring 45 thereon and the end flange 38, with a gasket 46 between said ring and flange. The inner end of the chamber is formed by a ring plunger 41 slidingly fitting both the inner surface of the member 39 and the outer surface of the sleeve 21. This plunger has its forward end thrust against the rear shouldered ends of the fingers 25 on the chuck sleeve 28. The forward strokes of the sleeve 20 and plunger 41 are resisted by a coiled expansion spring 48, the rear end thrust of which is against said shoulders, while its forward end thrust is against the flange 28 on the stationary sleeve 21. In the present instance, the forward end coil of the spring 48 seats in an annular groove in the rear face of said flange and this groove is of sufficient depth to extend into the socket 32, so that the end coil of the spring engages over the outer end of the set-screw 32 to prevent an outward releasing movement thereof.

A pipe Ell is connected to the chamber ii! through an orifice in the member 39 and has communication through a suitable control 52 both with a compressed air supply source to admit operating air to such chamber and with the atmosphere to permit an exhaust of air from the chamber as it may be desired to operate the chuck sleeve to eflect contraction or permit expansion of the c-ollet H.

The collet l1 preferably employed is of the type shown in perspective in Fig. 7. The workgripping jaw parts 54 of this collet are 01' segmental form and connected together at opposite ends by spring wires 55 in a manner to retain the difierent parts together as a unit and to normally effect relative radial expansion of the segments to work-piece released position. The collet is adapted to receive the stem 56 of, for instance, a valve 5'! to be ground or refaced and acts by relative contraction of the jaw parts to grip and firmly hold the stem, as understoodin the art. The outer end surfaces of the jaw parts are tapered to be engaged by the respective conical surfaces of the sleeves i 2 and 26 to effect contraction thereof, and these surfaces are preferably provided with bosses or balls to have combined contact with the sleeve surfaces and thereby reduce friction. Nothing new is claimed for this collet.

A gauge rod 58 projects centrally into the sleeves 2i and 21 for stop engagement at its forward end with the work-piece, and has its rear end adjustably held in a bushing 59 in the flange 38 by a set-screw threaded therethrough.

In the operation of the device, a work-piece stem may be inserted into an expanded collet i! when the sleeve I2 is being driven, the air chamber ii! at the time being free of air pressure and the chuck sleeve 28, 2| and piston 41 being retracted by the action of the spring 48. A work-piece having been positioned in the collet, the control 52 is operated to admit fluid pressure to the chamber it which effects a quick movement of the plunger 47 and chuck sleeve to the right to cause work-gripping contractionof the collet. This action is maintained during the grinding or refacing operation of the'work and upon the completion of such operation the control 52 is actuated to shut off the fluid pressure supply to the chamber 40 and to permit venting of the pressure therein to the atmosphere. The spring 48 then acts to return the chuck sleeve and plunger to normally retracted positions to permit expansion of the collet to release the work-piece.

I wish it understood that my invention is not limited to any specific construction, arrangement or form of the parts, as it is capable of numerous modifications and changes without departing from the spirit of the claims.

Havin thus described my invention, what I claim as new, and desire to secure by United States Letters Patent, is:

1. In a device of the class described, a rotatably mounted sleeve, a chuck sleeve mounted in said first sleeve to turn therewith and have longitudinal movements relative thereto, said sleeves having longitudinally spaced opposing collet engaging portions, a normally expanded coilet interposed between said portions to be engaged thereby and caused to contract when the chuck sleeve is moved in one direction, a third sleeve fitted into the rear end portion of said chuck sleeve and fixed to the first sleeve to turn therewith, means cooperating with said third sleeve to form a cylinder, a plunger movable in said cylinder lengthwise of said sleeves and having connection with said chuck sleeve to move it forward under cylinder pressure to effect contraction of the collet, means acting on said chuck sleeve and plunger to normally return them to retracted positions, and means controlling the admission of fluid pressure to and its exhaust from said cylinder.

2. In a device of the class described, a rotatably mounted sleeve, a chuck sleeve rotatable with and mounted for longitudinal movements in said first sleeve, said sleeves having opposed restricted portions and the chuck sleeve havin its rear end portion provided with longitudinally extending slots, a normally expanded collet mounted within the first sleeve between said restricted portions and operable to be contracted by said portions upon forward movements of the chuck sleeve from retracted position, means normally holding the chuck sleeve in retracted position, a third sleeve fitted into the rear end portion of said chuck sleeve and having portions projected through said chuck sleeve slots and fixedly connected tosaid first sleeve, means cooperating with said third sleeve to form a cylinder into which the rear end of the chuck sleeve projects, means Within the cylinder acting onthe chuck sleeve to normally retain it in rearwardly retracted position, a plunger mounted in said cylinderand in forward end thrust engagement with said chuck sleeve, and means controlling the admission of fluid pressure to said cylinder to cause forward movement of said plungerand chuck sleeve to efiect contraction of the collet and also operable to. shut. off the fluid pressure supply to. said cylinder and open the cylinder forexhaust of its pressure.

ROBERT S..BEVERLIN..

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