US3240020A - Collet chuck operating mechanism - Google Patents

Description

March 15, 1966 T. E. WILLIAMS 3,240,020

GOLLET CHUCK OPERATING MECHANISM Filed Sept. 13, 1963 F/a A INVENTOR. THEODORE E. Mil/4M5 to two criteria.

United States Patent 3,240,920 (BULLET CHUCK (WERATING MIE CHANlSM Theodure E. Williams, 11497 Sunset Blvd, West Los Angales, Calif. Filed Sept. 13, 1963, Ser. No. 308,707 7 tjlaims. Zl. e0 s4.5

This invention relates to an actuating device of the fluid pressure type and has particular utility when adapted for operative cooperation with metal working machinery.

It is well known to those skilled in the art that the production efliciency of metal working equipment may be substantially increased where the tool or work holding mechanism is provided with power means to move said mechanism to the open or closed position. A typical example of this type of device is disclosed and described in my Patent No. 2,726,090, issued December 6, 1955, for a Collet Chuck Operating Mechanism. Said patent illust-r-ates a typical use and location of the herein-disclosed invention.

The herein-disclosed invention is equally applicable to many types of metal working equipment, such as, for ex- 7 ample, automatic screw machines, turret lathes, grinding machines, polishing machines, chucking machines, mills and the like. Each of these machines is provided with a mechanism for the purpose of either holding a movable metal cutting tool or firmly gripping movable work piece. Such machines usually have draw or push type collets, expanding mandrels and power chucks. Characteristically such mechanisms are constructed with a centra longitudinally extended aperture arranged to receive an appropriate tool or work piece. The aperture is annularly surrounded by gripping elements which are arranged to move radially toward and away from the central aperture. This radial motion may be achieved by providing longitudinal slots separating the gripping elements. An-

nular cam surfaces are provided on the outer surfaces of each gripping element and in acute angular relation with the longitudinal axis of the central aperture. A complementing fixed cam surface annularly surrounds and engages the first mentioned cam surfaces whereby the gripping elements are cam biased to open or closed position as a result of linear longitudinal motion of the mechanism and slidable engagement between the first mentioned cam surfaces and the annular fixed cam surface. Early in the art, the linear motion referred to was provided by the manual operation. Such manual operation was patently time consuming. Consequently, the developing art dictated, and as noted above by the referenced patent, that power actuators be employed to provide the mentioned linear motion.

Characteristically, a simple cylinder-piston arrangement is employed, the latter being movable linearly in sequence to the action of a pressure fluid thereon. In fluid pressure actuators high pressured air is the most frequent source of primary power. This is due to the fact that reasons of economy has dictated that factory operators install high pressure air lines to their various production facilities. As a result, air operated equipment must be designed with the pressure limitations of existing compress-ed air systems in mind.

Production eificiency in machining operations responds They are the volume of metal removal per unit of time and piece part or tool change frequency per unit of time. A factor that materially affects metal removal per unit of time is the depth of cut that can be taken per revolution of the work piece or tool without work piece or tool slippage. A key fact-or in increased depth of cut is the total force available to grip the tool or work piece. As noted, the level of air pressure available as a power source is, for practical pur- Patented Mar. 15, 1966 poses, limited. Therefore, to increase the total force available for gripping the tool or work piece prior art design increased the total area of the piston upon which the air pressure acts. Patently an increase in piston size and the resulting larger mass increases the time required to move the larger piston through each cycle. Thus efforts to increase the gripping force in this manner tends to reduce the time efiiciency of the loading and unloading operation. Additional disadvantages are that as the size of the actuator increases it becomes more bulky and more difficult to handle as well as to install on existing equipment set up time is thus increased. In some instances the installation of an actuator on existing equipment is impossible, without substantial reconstruction thereof. Such modification is not desired as it may impair the original functional purpose of the equipment.

With the above in mind it is a general object of the disclosed invention to provide an actuating device of the type hereunder consideration which offers a substantial magnification of available force to thereby improve the efiiciency of the machining operation.

It is a further object of the invention to provide an actuator which offers the mentioned force magnification Without impairing the etficiency of the loading and unloading operations.

It is yet a further object of the invention to provide an actuator having the advantages mentioned that is compact and easily handled and readily adaptable to existing equipment.

Specifically, a prefer-red embodiment of the invention oomprehen-ds a primary linearly movable air actuated piston. The structure of the primary piston includes a secondary piston movable therewith, the latter being operatively disposed within a closed fluid pressure chamber forming one operative limit thereof. A third piston is also disposed within the closed pressure chamber and forms the other operative limit thereof. It will thus be understood that a primary force magnification is available as a result of the action of the air under pressure on the primary piston. Additionally, a secondary force magnification becomes available as a result of the action of the secondary piston on the closed pressure chamber and the action of the latter on the tertiary piston.

These and other objects and advantages of the disclosed invention will become apparent in the course of the following description and from examination of the disclosed drawings, wherein:

FIGURE 1 is a diagrammatic view of a typical actuator installation;

FIGURE 2 is a vertical sectional view of a preferred embodiment of the herein-disclosed actuator;

FIGURE 3 is a detail second vertical sectional view of that portion of the operating actuator that is subject to rotational motion during operation.

Describing the invention in detail and directing attention to FIGURE 1, it will be understood that the numeral 16 diagrammatically represents an operating element of a typical metal working machine such as a lathe headstock. The numeral 12 diagrammatically represents the herein disclosed actuator operatively mounted in a conventional manner on the headstock 10. While the details of the structure are not here shown, the numeral 14 illustrates a usual work or load holding device, such as a collet, which may be biased to an open and to a closed position by the linear motion of the actuator 12. A fluid pressure supply is indicated by the pipe 16, which in turn may be connected to any source, (not shown) such as a compressed air system. A main shut off valve 18 and a pressure gauge 20 are also provided in line 16. The line 16 is in direct communication with a typical four-way valve 22, the latter being ported as at 24 and 26 directly to lines 28 and 36, respectively. Lines 28 and 3% in turn respectively communicate with ports 32 and 34 of the actuator 12. The operation of the conventional valve 22 will be readily understood in that, as the handle 36 is moved to its various positions air under pressure is selec tively directed to either of the lines Zii or 30, and, as each line receives air under pressure, the other line is directed to exhaust.

FIGURES 2 and 3 disclose a preferred embodiment of the invention and show same in central vertical sectional view. With this in mind it will be understood that all of the parts illustrated are of annular construction and surround the central longitudinal axis of the actuator. Thus, an annular housing 38 is provided, said housing defining within itself a primary pressure chamber 40. The pressure chamber 40 is ported as at 32 and 34 to provide access to the pressured air. A first annular bearing arrangement is indicated generally at Said hearing 42 comprises an outer race 44, fixedly mounted within the housing 38 and an inner race 4-6 operatively joined by the rollers 48.

A primary'piston, indicated generally at 56, is disposed within the pressure chamber 40 and comprises a first annular segment 52 having oppositely directed ring packings 54 and 56 conventionally disposed in the outer peripheral surface thereof. The segment 52 additionally has an inner ring packing 58 conventionally disposed on the inner annular surface thereof. The primary piston t) further comprises a longitudinally directed annular skirt 60, which defines a bearing cavity 62 in which is pressure fitted the outer race 64 of a secondary bearing indicated generally at 66.

End wall 68 having an inner annular ring packing '76 in sealing engagement with skirt 60 closes the left aspect of the pressure chamber 44) and is conventionally secured and sealed to the housing 38. The housing 38 further comprises a radially inwardly directed wall 72, which defines the right aspect of the pressure chamber 4t? and at its inner terminus is provided with a longitudinally directed annular guide wall 74. It will be noted that the inner peripheral surface of the primary piston 59 guidably bears on the outer surface of the wall 74. A seal is provided by ring 58.

The longitudinally directed skirt 60 of the primary piston 50 has an inwardly directed integral abutment wall 78 which cooperates with snap ring 80 to fixedly lock the outer race 64 of the bearing 66 in place. It will be understood that the bearing 66 is preferably of a combined thrust and rotational type.

Attention is now directed to FIGURE 3 wherein the number 84 generally indicates a secondary piston. This secondary piston comprises a longitudinally extended annular member 86 having an outer annular surface 88, which lockingly receives the inner race 9t) (FIGURE 2) of bearing 66 via the snap ring 92 and threaded collar 94 (FIGURE 3). The right terminal portion of secondary piston 84 is provided with an annular outwardly directed shoulder 96, the latter having pressure surface 98 at one side thereof.

Recalling that the actuator herein disclosed is adapted to be associated with various types of metal working equipment, it will be understood that, for illustrative purposes, the numeral 100 designates the threaded terminal end of a machine spindle of, for example, the lathe headstock 10. A fragmentary portion of the spindle is shown. An adapting collar 102 is threadably mounted on the spindle 1th) and in turn is connected by a bolt as at i, to an annular bearing retainer 166. The bearing retainer 1&6 is threadably connected at 163 to an annular secondary housing 110. The housing 11th internally (lefines secondary pressure chamber 112.

Typically, the spindle 100 is hollow, hence accomodates the telescopic disposition of a push tube 114 therein. The push tube 114 is only fragmentarily illustrated, but it will be understood that it may extend through the spindle for conventional (not shown) operative connection to the collet 14. 5

The secondary pressure chamber 112 telescopically receives a third or actuating piston indicated generally at 16. The piston 116 comprises an annular radially directed drive plate which abuts, as at 120, the adiacent end of push tube 114. A longitudinally directed inner skirt 122 is annularly coextensive with the inner diameter of the drive plate 118 and is telescopically received within the secondary piston 8 -3 to accommodate relative longitudinal motion therehetween at the surface 124-. The piston 116 further includes an annular longitudinal pressure skirt 125 which is disposed in secondary pressure chamber 112, and surrounds the adjacent end of secondary piston 84. To appropriately seal the secondary pressure chamber 112 conventional ring packings 127, 128 and 13%) are provided. Wiper rings are provided at 132 and 134 respectively, to avoid contamination during actuator action hereinafter described.

To provide a unitary actuator piston the pressure skirt 126 may be connected by a dowel pin 136 to plate 118. To accommodate the motion herein contemplated, another dowel pin 138 is press fitted as at Md in the plate 318 and slip fitted within the drilled hole 142 of the bearing retainer iii-6. Further, a dowel pin 144 may have one end press fitted within the drive plate 118, as at 145, and the opposed end slip fitted within the drilied hole 14-6 of the secondary piston 84. Thus rotary motion of the spindle 100, the adaptor 1G2, retainer 186 is transmitted to the actuator piston 116 and the secondary piston 84. If desired, a plurality of dowel pins may be utilized in the mechanical connections referred to above. Thus the entire structure of FIGURE 3 rotates in device operation.

Returning to FIGURE 2 it may be seen that the actuator piston 116 may be provided with a plurality of cavities 15d, distributed in equal angular spacing around the forwardly facing surface thereof. The bearing retainer 1% may be provided with a plurality of facing and complementarily aligned cavities 152 distributed on the inner surface thereof. Compression springs 154 are re ceived within the cavities and 152 and arranged to pressure the gauge the actuator piston 116 and bearing retainer respectively. The number of compression springs may be increased as design requirements dictate.

The secondary pressure chamber 112 is initially completely filled with an appropriate fluid such as a relatively incompressible oil via the fill line 160. As the chamber 112 is filled with the oil, air may be evacuated therefrom via bleeding ports 162 or 164.

In operation, it is desired to move the push tube 114 linearly to the right as seen in FIGURE 3, which, as noted, achieves collet closure. The machine operator initially sets lever 36 of valve 22 to the appropriate position. Compressed air is admitted via port 34 to the righthand side of the piston 52 and in the primary pressure chamber 40. Concurrently, the port 32 allows evacuation of air from the lefthand side of the piston 52. As a result, the piston 52 is moved quickly to the left to the limit of its stroke and into abutting engagement with the wall 68. The secondary piston 84 is concurrently carried to the left as a result of the mechanical connection at the thrust bearing 66 with piston 52. This motion causes the relatively small pressure surface 98 to bear against the relatively incompressible fiuid in secondary pressure chamber 112 creating a high unit pressure therein. The unit pressure of the liquid being uniformly directed throughout the body thereof is distributed over the relatively iarge surface 17%) of the actuator piston 116 urging the actuator piston to the right as seen in FIGURE 3. Movement of the actuator piston to the right induces compression of springs T154 and further induces rightward motion of the engaged push tube 114. Collet closure results. Upon operator resetting of the valve 22, compressed air is now admitted to the primary pressure chamber 40 via port 32 and exhaust is accommodated via port 34. Thus the primary piston is returned to the right to the position shown in FIGURE 3 and the secondary piston 84 is again carried therewith. Pressure on the hydraulic fluid trapped in chamber 112 is thus relieved and the now compressed springs 154 urge the actuator piston 116 to the left or release position shown in the drawings.

It will be particularly noted that the entire action described is undertaken without halting spindle rotation. The outer housing 38 as well as the primary piston 52 remain rotationally stationary. The housing 38 is linearaly stationary as well. The primary piston 52 moves only linearly. The secondary piston 84, the actuator piston 116 move both rotationally and linearly. The secondary housing moves only rotationally.

It will thus be noted that the relatively large closing surface area of the primary piston 52 on the right face thereof, is available for substantial force magnification from line pressure. Thereafter, this now magnified force is distributed to the closed pressure chamber 112 and against the liquid trapped therein. A substantial secondary magnification is achieved by virtue of the distribution of such unit pressure against relatively large surfaced actuator piston 116. This large force magnification increases the stock or tool gripping power, improving as above noted, the efiiciency of the machining operation. Additionally, the disclosed invention has the mentioned advantages of compactness and of ready adaptability to existing metal working equipment. The actuator has the further advantages of rapid closure uniformity of grip regardless of stock size variation and long service life with minimum maintenance.

Having described a preferred embodiment it is to be understood that the invention is not limited thereto and may be subject to modification without departing from the scope of the appended claims.

What is claimed is:

1. In an actuating device, a housing defining therein a primary pressure chamber, a linearly movable primary piston disposed within said primary chamber, a fluid power source operatively communicating with the primary chamber to selectively apply pressure on said primary piston to induce motion thereof, a "linearly and rotationally movable secondary piston operatively connected to the primary piston and movable linearly in response to the movement of the former, a secondary pressure chamber having pressure distributing fluid therein, said secondary piston being operatively disposed in said secondary chamber, a linearly and rotationally movable tertiary piston operatively disposed in said secondary chamber, said tertiary piston being movable in response to movement of said secondary piston and the distribution of pressure through said distributing fluid and bearing means accommodating concurrent rotational and linear movement of said secondary and tertiary pistons.

2. An actuating device according to claim I and including spring means compressibly engagable with said tertiary piston and being operative to reverse the linear movement of said tertiary piston upon release of the pressure applied to said primary piston.

3. In a force multiplying actuating device, a stationary housing, a first pressure chamber in the housing, a movable first piston disposed in said chamber, pressure means communicating with said chamber and operative to induce motion of said first piston, a second piston, connec tion means providing a mechanical connection between said first and second pistons to accommodate concurrent movement thereof, a movable third piston carried by the device, and a force multiplying connection between the second and third pistons whereby said third piston moves in response to movement of said other pistons, said force multiplying connection comprising a closed hydraulic chamber having the second and third piston movably disposed therein, first bearing means fixedly carried by such stationary housing, and second bearing means, all of said bearing means accommodating concurrent rotational and linear movement of said second and third pistons.

4. A force multiplying actuating device according to claim 3, and including other pressure means operative to reverse the linear movement of at least one of said pistons upon release of said first mentioned pressure means.

5. In a force multiplying actuating device adaptable to gripping mechanisms of metal working equipment, an outer stationary housing, first bearing means having an outer race fixedly carried by the stationary housing, said housing defining a first pressure chamber, a source of compressed air communicating with said chamber, a first piston disposed in the chamber and linearly movable through a predetermined stroke upon the application of compressed air thereto, a second housing telescopically disposed within the first housing, the inner race of said first bearing means being carried by said second housing whereby said first bearing means accommodates rotational movement of said second housing relative to said outer housing, said second housing defining a second pressure chamber therein, ran actuating piston disposed in said second chamber and linearly movable through a predetermined stroke less than said first mentioned stroke, and pressure applying means operatively interconnecting the first chamber and said second chamber, said pressure applying means including a second piston movable with and having a bearing connection to the first piston accommodating relative rotational movement therebetween, said pressure applying means including means to magnify the total pressure of output of said actuating piston and reduce the linear stroke thereof.

6. A force multiplying actuating device adaptable to gripping mechanisms of metal working equipment according to claim 5, wherein said last mentioned means comprises a relatively incompressible fluid trapped in said second pressure chamber, a first surface on said second piston for pressured engagement with said fluid upon determined movement of said second piston, and a second surface having an area substantially greater than said first surface on said actuating piston and arranged to be pressure engaged by said fluid.

7. A force multiplying actuating device adaptable to gripping mechanisms of metal working equipment according to claim 6, and including spring means pressure engaging the actuating piston and operative to reverse the linear movement thereof upon the release of the applied compressed air to the first piston.

References Cited by the Examiner UNITED STATES PATENTS 579,441 3/1897 Parfitt 60-545 X 582,839 5/1897 Winans 60-545 675,880 6/1901 Carlisle 60-545 X 825,301 7/1906 Coddington 60-545 X 1,037,031 8/1912 Martin 60-545 2,173,583 9/1939 Forichon 60-545 2,388,877 11/1945 Souter 60-545 X 2,829,498 4/1958 Ferguson 60-545 3,059,433 10/1962 Hirsch 60-545 FOREIGN PATENTS 929,959 7/ 1947 France. 704,657 4/ 1941 Germany.

SAMUEL LEVINE, Primary Examiner.

ROBERT R. BUNEVICH, Examiner.

Claims (1)

1. IN AN ACTUATING DEVICE, A HOUSING DEFINING THEREIN A PRIMARY PRESSURE CHAMBER, A LINEARLY MOVABLE PRIMARY PISTON DISPOSED WITHIN SAID PRIMARY CHAMBER, A FLUID POWER SOURCE OPERATIVELY COMMUNICATING WITH THE PRIMARY CHAMBER TO SELECTIVELY APPLY PRESSURE ON SAID PRIMARY PISTON TO INDUCE MOTION THEREOF, A LINEARLY AND ROTATIONALLY MOVABLE SECONDARY PISTON OPERATIVELY CONNECTED TO THE PRIMARY PISTON AND MOVABLE LINEARLY IN RESPONSE TO THE MOVEMENT OF THE FORMER, A SECONDARY PRESSURE CHAMBER HAVING PRESSURE DISTRIBUTING FLUID THEREIN, SAID SECONDARY PISTON BEING OPERATIVELY DISPOSED IN SAID SECONDARY CHAMBER, A LINEARLY AND ROTATIONALLY MOVABLE TERTIARY PISTON OPERATIVELY DISPOSED IN SAID SECONDARY CHAMBER, SAID TERTIARY PISTON BEING MOVABLE IN RESPONSE TO MOVEMENT OF SAID SECONDARY PISTON AND THE DISTRIBUTION OF PRESSURE THROUGH SAID DISTRIBUTING FLUID AND BEARING MEANS ACCOMMODATING CONCURRENT ROTATIONAL AND LINEAR MOVEMENT OF SAID SECONDARY AND TERTIARY PISTONS.

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