US2660984A - Machine tool with liquid spring actuated ram - Google Patents

Description

Dec. 1, 1953 R. F. ZUMWALT MACHINE TOOL WITH LIQUID SPRING ACTUATED RAM 2 Sheets-Sheet l A ,Q.

Filed March 1, 1951 R. F. ZUMWALT 2,660,984

MACHINE TOOL WITH LIQUID SPRING ACTUATED RAM 2 Sheets-Sheet 2 Filed March 1, 1951 fi af ZQIIQ? :I: @70

Dec. 1, 1953 INVENTOR.

Faber! FZumwaZt Patented Dec. 1, 1953 MACHINE TOOL WITH LIQUID SPRING ACTUATED RAM Robert F. Zumwalt, Kenmore, N. Y., assignor to Wales-Strippit Corporation, North Tonawanda, N. Y., a corporation of New York Application March 1, 1951, Serial No. 213,322

10 Claims. (01. n -13) This invention relates to a work-performing instrumentality which is operative during one stage to compress a fluid medium and in so doing store energy therein and which is operative during a second, or Work-performing, stage to release and utilize such energy; and more particuiarly the invention is concerned with improvements in the work-performing instrumentality disclosed and claimed in the application of Paul H. Taylor, Serial No. 21 ,403 filed March The invention has many and varied applications. For example, it is advantageous in many press-working and forging operations to emplcy' a drop hammer for carrying out desired pressworking or forging operations upon work-pieces supported upon an anvil, or die.

In most operations of this type, it has heretofore been the practice to employ a double-acting air or steam cylinder for elevating the heavy hammer to theposition at which it is released so that the force of gravity may be utilized to effect the, working stroke of the hammer, the double-acting air orsteam cylinder alsobeing available to accelerate the hammer in itsworking stroke and to thereby increase the forces available for the press-working or forging operations. The utilization of the force of gravity and/or air or steam in the above manner has a number of objections. vThe air or steam employed for operating such cylinders ordinarily does not exceed 500 p. s i. Hence a large air or steam cylinder is required to elevate a ham- H161 and properly accelerate it, upon its release, in-the direction of the anvil or die. Such large cylinders and associated parts are costly to machine, assemble. and service. Moreover, the hammer and other actuating parts employed must necessarily be heavy. Other objections are the length of travel required to accelerate the hammer, the slowness of acceleration owing to the forces available for this purpose and the difficulty in controlling the stroke of the ham mer and dissipating the dynamic energy created thereby.

In the work-performing instrumentality disclosed in the application referred to, as is also true of the present invention, a fluid medium is compressed tostore energy therein and. is permitted to expand so that the released energy may be utilized to actuate a member, ram,-

for example, which is to be advanced to per" form a working stroke. In such an instrumentality there is a possibility that if a Work-piece is not present on the anvil or die, or-is present but not of the proper configuration, and provision is not made to guard against this, the entire dynamic force of the ram will be trans mitted by impact to the anvil or die. Such an occurrence may cause various failures including damage to the ram.

The principal object of the present invention is to overcome the above objection, this object contemplating a dynamic work-performing instrumentality of the type generally described wherein provision is made for cushioning the ram, or other member, as it approaches the-end of its working stroke in the event that the dynamic forceofsuch ram, or member, has not been otherwise dissipated.

A further object is to provide a novel means for cushioning the impact of the ram, or other work-performing member.

A still further object is a work-performing instrumentality in which the movement of the ram, or other member, is arrested at the end of the working stroke by a compressible fluid medium. 7

A still further object is to provide a cushiom, ing means of the character described which will be operative to dissipate the dynamic force of the Work-performing member through a smali portion, of the stroke thereof and which will not interfere with the normal operation of the workperforming member throughout its normal range of movement, becoming effective only after the work-performing member passes the point of normal impact.

A still further object is to provide a workperforming; instrumentality wherein the parts are so designed that the normally incompressible fluid availed of in compressing the fluid which actuates the work-performing member may be trapped in such a manner that, it will'become compressible to cushion the work-performing member at the limit of its working stroke in the manner contemplated.

A still further object is a arrangement of the parts of the work-perform ing instrumentality, whereby to provide for s mplicity and economy in construction and facilitate fabricatingassembling and servicing operations,

The inventionv is illustrated in the accompanying drawings, in which:

Figure 1 is a diagrammatic view of a work-.

, Figure 2 is an enlarged vertical section through the portion of the press which includes the ram novel design and the features of the invenand the associated ram energizing parts and is taken along line 22 of Figure 1, the ram being shown extended to the limit of its working stroke; Figure 3 is a similar section in which the ram is shown in its retracted, or loaded, position; and 5 Figure 4 is a fragmentary section on an enlarged scaleshowing a iportionv-of, the stationary piston, a portion of the upper cylinder; and "a portion of the sleeve which is secured to this cylinder, and associated parts, and showing in a.- 1osomewhat diagrammatic and exaggerated manner how leakage of the motive'fiuid' may'occurto effect retraction of the ram.

The invention is illustrated byawayflof example. in connection with a press which:isisumeientlyvlaillustrated for the purpose in view by a showing: of an overhead support I0, a.ram II and an. anvil or die I2, the frame-work'by'which'theover head support and ram are mounted in thedesiredi relation with respect to the anvil or die constitut 2 ing norpart of theinventionand hence not..beingr. illustrated. A 'worliepie'ce .I3 'is shown .supported. uponithe anvil or die. I2 "under the ramJ I'.

The ram II is energizedfbya. lowepressure; hydraulic system hilwhich includes. a reservoir I5, a pump I 6' and an accumulator Il'. Fluid. underpressure is conductedby a. pipe. I 8.from .the pump. andaccumulator. through .a .relif..'val've. I 9. tol.a. two-way selector. valve 20. The latter is included in .a-pipe. 2.! andis operativein one position of adjustment to permit. energizing ...fluid.. under pressure tov enter. a conduit 22. to retract. the ram II.'in-.a.manner.tofl be described. In a second. position of. adjustment. oftlie. selector valve 26, fluid may leave thepipe 22Iduring workingstrokesof the ram andreturn to the reservoir lithroughthe selector-i'valv'e, pipe 23 and'checkvalve 24. The relief "valve 'ISJmaintainsconstant, the pressure of the fluid .deliveredftothe conduit Z2'.by.by=p.assing excess fluid through reIiefJvalVe I 9, pipe 25. and check valve 24 to. thereservoir. I 5.. The fluid employed in the low-pressure hydraulic system is preferably'a liquid suchas mineraLoiL. for. example, and thesystem-is so designedthat' the. desired. energizing pressures are obtainedwithout-compression of such-fluid.

The manner in'which thefiuid .from .the.lowpressure hydraulic systemais utilizedjto. operatetheram .I I is illustrated inFigi'l'res2iand .3'..- Re.-

ferringjto. theformer figure, it .will' be notedthat. w; the-rain] is hollowand that the interiorthereoff providesa chamber 26"f0r'accommodating a body. of fluid 21 which may be, and preferablyis', an. oil-.or. otherliquid which is more', compressible than the minemLoiLor" liquidfimpldyedinihe '54 as'ele'vated expands" rapidly to its no a1 1 I t rm v0 f low pressure hydraulic'fsyst'em, a; silicone voil; for. U example. The ram. II has an open upper end. which is threaded as at 'ZBandwhich 'isr'enlarged' to provide an internal shoulder'29 A cylinder30. occupies the chamberFZS; the 'exter'naldiameter of. the cylinder 30. being .substantially "le'ssfthan the diameter of the chamber z'fiand'the lower end" of the cylinder being spacedfro'm the bottom .of' said chamber;. as illustrated. The upper end of. the cyinder 3Il'is formed with aflange 3Ijwhich. seats .upon the shoulder'29 tosupport the cylinder in the chamberififasuitable sealing .ring;32; beingcarried in an annular channel'inlthe shoul der 29 and cooperating with the flange 3| on the cylinder to prevent leakage "of the fluid medium 7 between the shoulder and'said flan'ge.

The cylinder 3i issecured. in: the. ram. I I. in. the manner described by the lower end of an upper. cylinder. 33, the lower. end of the-latter being. externally" threaded andoccupying. the 1 7 threaded open end of the ram I I so that the flange 3| of the cylinder 30 is tightly held between the shoulder 29 and the lower end of the cylinder 33. The rain II, cylinder 313 and cylinder 33 are thus secured together so that they will move as a unit incident to the operation of the ram.

Aismall diameter piston 34' occupies the cylinderf30 while. a: large diameter piston 35 occupies the cylinder 33. The pistons 34 and 35, in the embodiment illustrated, are integral and are carried by a tubular member 36, the upper end of th'elatterrbeing suitably connected to the overhead support Ill. The tubular member 36, as shown is integrally connected at its lower ,enditoitherupperrend of the piston 35, the pistons 34ahd-35and the-tubular member 36 being axially aligned and being supported as a stationary unit by-the "overhead-member I II.

A 'sleeve'-31 having an externally threaded cen-- tral portion is screwed into the upper end of the cylinder. .33. and isv slidable.-.a1ong:...the....tube.- .36 duringroperationof. the ram. Thesle'eve 3T and:

the. tubular .member336 may carry-.sealinglrings Hand. 4!), respectivelyltd prevent leakageof. the. low pressurelhydraulic; .fliiidv which is supplied tothe tubular member. 36. from the low pressure hydraulic system "while. the piston 35 may bev providedwith a similar sealing ring .4 I

The lower end'ofy'the tubular member 36.15; ported at 42 sothat fiu'idfrom thesaidmember. may enter the annular space between the tubular. member. and the inner wall of the cylinder 33 and act against the end ofthe sleeve 3T'to cause the. cylinder 33 to be elevated to :the position shown in Figure 3'. As the cylinder -33"is elevated in? the manner described, the ram I land cylinder .30 are elevated with'it: Consequently,..as the piston. 34 is stationary, the fluid in the. chamber ZIwill be compressed. This'is'clearlyillustrated in Fig: ure 3 wherein'itwilllb'e noted that the cylinder 30' is entirely occupied by the piston. .34. As the body of liquidz Thus the chamber 26 when inits. incompressedLstate .and .when the. ram II. is in. theextended positiomit'will'beapparent that as the ram is elevated in the. manner described, .the body 'offluid 2T willbe reduced in volume and. energy will thereby be stored in said .body of.fluid.1

Assumingthe. ram II to occupy theelevated position shown "in Figure '3',ifa working strokeof the ram isefie'cted by; adjustingjthe selector valve 20.50 thatthe fluidjin the cylinder 33"may exhaust. through the pipe 22f-and'return1through the selector valve 20 and check.valve 24 to the reservoir I 5. As'this occurs, the'bodyof fiuid 27 in the chamber 26, which was'compressed when the ram umeandin" so: *doing transforms. the pressure existing in'ithe chamber 26'into kinetic energy, and rapidly accelerates the rain .I I inthedirection.

0; of the anvil or. die toefiect.apresseworkingopera:

tion upon the work-piece supported thereon. The: press-working operation is. efie'ctedby theimpact: offthe. ram I I rather than.by-.-a..squeezing operation .such-asicharacterizesa; conventional pressworking operation.

As noted, as theefluidrin--;the;.chamber.26 expands to actuate; the rram l l-iinrthe manner de. scribed, thecy-linderSS .descends,- forcing'the fluid in .the:cylinder::33;(out-through: the: ports 42 and i into the tubular; member73'3-so;1that it may ex haust intc-the=reservoir.:.l5:. In'accordance with-- the invention the portsfl ;are:located above the head of the piston.35 so thataswthe ram: II approaohesthe limit ofa itsworkingstroke; a-body of fluid=43- Fieure :2). will be-trapped .iIli the cylinder;

33 in the annular chamber delimited by said cyl-5 inder, tubular member 36, piston 35 and sleeve 31. The body of fluid thus confined is compressible and resiliently resists any further downward movement of the ram, providing a fluid cushion which will not interfere in any way with the desired reciprocatory movements of the ram and ordinarily only coming into play in the event that a work-piece is not on the anvil at the time the ram is operated or if, for any other reason, the ram would otherwise strike the anvil. The parts are so designed that actuating fluid may leak between those parts of the tubular member 36 and the sleeve 31 which provide walls of the trap in which the fluid 43 is accommodated, it being noted in this connection (see Figure 2) that no seals are employed in connection with these parts of the tubular member 36 and the sleeve 31. Thus some of the trapped fluid may escape through the ports 42 as the ram H approaches the limit of its working stroke and as the trapped fluid 43 is compressed in the manner and for the purpose described. When the energy of the ram II is dissipated and when, preparatory to a suc ceeding working stroke, actuating fluid is again supplied through the tubular member 36, a portion of such fluid may leak through the ports 42 and into the annular trap chamber so that such fluid may act between the piston 35 and the lower end of the sleeve 31 to retract the ram ll until the ports 42 are again open. The leakage path is shown in exaggerated manner in Fig. 4, this figure being a fragmentary section taken at the left of Fig. 2 at and adjacent the pocket in which the fluid 43 is trapped.

Preferably a port 33a connects with atmosphere the portion of the cylinder 33 below the piston 35, whereby to permit entry of air into and its escape from such portion of the cylinder during the operation of the ram;

The construction described has the advantage that the fluid medium in the low pressure hydraulic system is utilized to provide the fluid cushion and although said fluid medium is normally incompressible the parts may be so designed that the confined body of fluid 43 will be compressed to absorb energy as the ram approaches the limit of its working stroke.

The piston 34 may carry sealing rings 34a for preventing escape of fluid from the chamber 26 between the cooperating walls of the piston and the cylinder 30. If desired, the sealing rings 34a, may serve only during the low-pressure portion of the compression strokes and sealing during the high-pressure range of such strokes may be obtained by so designing the cylinder 30 that it will be compressed around the piston as dis closed and claimed in the copending application of Paul H. Taylor Serial No. 180,966, filed August 29, 1950. I

The work-performing instrumentality described. has a number of highly desirable advantages. The parts may be so designed that extremely high forces may be developed in the com pressed fluid by a low-pressure hydraulic energizing system, it being apparent that the parts may be so designed that any desired pressure, within limits, may be developed in the chamber 26 by the energizing fluid supplied to the cylinder 33. For example, the parts may be so designed that a pressure of 30,000 p. s. i. may be developed in the chamber 26, thereby pre-loading the ram H in its fully retracted position so that upon release of pressure in the chamber 26 in the manner described, the, ram II will be actuated to. r

g l utilize such energy in a press-working operation.

It will be noted that the energy which is released by the expanding fluid in the chamber 26 r is transferred to the ram ll throughout its full range of movement 50 that the reaction forces acting on the supporting frame structure are progressively transmitted to the latter in a similar manner. As the forces to which the supporting frame structure is subjected are dissipated over the entire stroke of the ram, such structure may be relatively light and of corresponding low cost.

Although the use of oils and liquids of different compressibilities in the low-pressure hydraulic system and high pressure energy storing system has been described, it will be apparent that the work-performing instrumentality contemplated is of such a character that oil or other liquids of the same compressibility may be employed in both systems, if desired.

' The features of the invention may be employed to advantage in connection with various devices having a member which is advanced incident to a work-performing stroke and which is retracted preparatory to such a stroke. The specific embodiment illustrated and described, therefore, is intended by way of example only.

I claim as my invention:

1. A device having a member which is advanced to perform a working stroke and which is retracted preparatory to a succeeding working stroke, said member having a chamber in which a body of liquid is confined, a cylinder extending into said chamber and spaced from the walls thereof, a stationary piston which occupies said cylinder, means for retracting said member and in so doing cause said piston to compress said body of liquid, means for relieving said last mentioned means so that said body of liquid may expand to effect said working stroke of said member, and means for cushioning said member as it approaches the limit of said working stroke.

2. Apparatus of the character described comprising a member having a hollow chamber therein, a cylinder extending into said chamber, said cylinder having its inner end open and com municating with said chamber, said chamber and cylinder being filled with a body of liquid and confining said body of liquid, a piston reciprocable through the outer end of said cylinder, a second piston rigidl secured to the first piston, a second cylinder rigidly secured to the first cylinder and in which said second piston reciprocates, means including a port through which a hydraulic motive fluid may be supplied to and exhausted from one side of said second piston to advance and retract the first piston in the first cylinder, said first piston when advanced into said first cylinder compressing said body of liquid, and valve means controlling the direction of flow of the hydraulic motive fluid to said one side of the second piston, said port being spaced sufficiently from said one side of said second piston that a body of said hydraulic motive fluid is trapped between said second piston and said second cylinder, when said valve is on exhaust, to cushion the last part of the movement of said second piston in said second cylinder when said valve is on exhaust.

3. A compound fluid motor comprising a hollow member open at one end, a cylinder extending into said hollow member and open at its inner end to communicate therewith, a piston reciprocable in said cylinder, means including said cylinder and said piston for closing the open end of said hollow member, said hollow member and: cylinder being fi'lled. with 1 a:'-. body: of liquid which isof high compressibility, asecon-d piston secured to the first piston; a--,sec0-nd cylinder in which the second zpiston reciprocates, said 7 secondcylinder being; secured to the first cylinder; means-including a port for supplying a liquidof low compressibility between one end ofthesecondpiston and the-adjacentendof the-second cylinder and for exhausting. said lastenamed liquid therefrom-to compress said bodyiofhighly compressible liquid and to permit: the same to expand; respectively, and a ,valve controlling;- the directionof flow of theliduid of low compressibility, said .portbeing spaced from said second piston a sufficient distancezto trap a bodyof said sece ond-liquid between saidsecond piston-andsaid second cylinder when said second cylinder-is-on exhaust, to cushion thelast part ofthe-relative movement between said secondrpi-ston-and said second cylinderWhensa-id second cylindenis on exhaust.

4: Apparatus of the characterdescribed comprisinga reciprccable member havingi-ahollow chamber therein, a cylinder extending, into said chamber and spaced from the inside wall of saidchamber, said cylinder havingits inner end openand communicating with" saidchamber, said chamber and cylinder being filled with a body'of liquid and-confining said body of liquid, astationary-piston reciprocable through the outer end ofsaid cylinder, a secondpiston rigidly secured to the first piston, a second cylinder rigidly secured co-the first cylinder and in which said second piston reciprocates, a-tube connected to the first piston having ports therein for supplying and. exhausting a second liquid :to and from one side ofthe second piston, said ports being spaced from said second piston so that abody of the second liquidis trapped between the second piston. and

the secondicylindernear the end-of themovee I ment of the second piston in the second cylinder when the second cylinder is on exhaust, and a valve controlling the direction of flow of the second liquid through said tube and ports.

5. A device having a member which isadvanced toperform a working stroke and-which is retracted preparatory to i a succeeding working stroke, said member having a chamber in which a body of fluid is confined and providing a cylinder; stationary first and second connectedpistons, said first piston occupying said cylinder, a

fluid motor having a second cylinder connected to said member and occupied by saidsecondpis-i ton, means-for supplying a second fluid under pressure to, said motorrto effect relativemove: ment betweensaid secondcylinder andsaidsecond piston and in so doing cause said first piston to compress said body of fluid, meansforvrelieying said last mentioned means so that said body of fluid may expand to effect. said working. stroke of (said member, and means includingv said sec: ond cylinder and piston for trapping a body of said second. fluid to cushion said member as it approaches the limit of said working stroke.

6. A device having a member which is advanced to perform a Working stroke and which is retracted preparatory to a succeeding working stroke, said member having a chamber in which a body ofliquid is confined, a cylinder extending into said chamber and spaced from the walls thereof, stationary first and second connected pistons, said first piston occupying said cylinder, a fluid motor having a second cylinder connectedyto said member and occupied by said second piston,

meansforsupplying asecond liquid under pressure -to said; motor. tozeffecti relatives; movement betweensaid second cylindenand said second piston and m sc-doing: causesaid first piston to compress, said-body of'liquid, means for relieving saidfiuid- "motorsoz-that'saidibody of liquid may expand to effect said working stroke of said member, and means including said-second cylinder and piston fortrappingand compressing a body oft-said second liquid. to cushion said member as itapproachesthe limit of said working stroke.

7. Av device; having. a member which is advancedato perform a'workingstroke-and which is retracted'preparatory to a succeeding workingstroke, said member having a chamber in which abody offluid is-confined, a cylinder extending into. saidchamber; stationary first and second aligned,- connected pistons, said first piston occupying said, cylinder, a reciprocatory fluid motor-having a second cylinder connected to said member and occupied? bysaid second-piston,- a stationary tube. which enters and which communicates withsaid second cylinder and axially oftwhich;said.second,:cylinder may slide, means for, supplying, a second fluid. under pressure through said tube to'the interior of said second cylinder. to.. effect relative movement between said second cylinder: and said second piston and in so doing, cause saidfirst piston to-compress said .body of fluid,means-forpermitting the fiuid in saidsecond cylinder to exhaust :so that said bodycf .fluid may expand to effect saidworkin stroke of said member, and .means for trapping abody of said second fluid in said second cylinder to) cushionsaid member. as it approaches the limit of said working stroke.

8. Adevice: havingamember which is advanced to performa workingstroke and which is, retracted, preparatoryto asucceeding working v stroke, said member having a chamber in which a body of fluid is-confined, a cylinder extending. into said. chamber, stationary first and secondpistons, said first piston occupying said cylinder, areciprocatory fluid motor having a second cylinder connected to said member and occupiedibysaid secondpiston, a stationary tube which entersandwhich communicates with said second cylinder and axially of which said second cylinder may slide, said first andsecond pistons and saidtubepbeing seriallyconneoted in axial alignment, means for supplying ..a second fluid underpressure. through said tubeto the interior Qfisaid second, cylinder to retract it and in so doing cause.,said, first piston to. compress said body, of fluid, means for permittin th fluid in Said.secondcylinderto exhaust so that said body of fluid may expand to effect said working stroke of,v saidmember, and means for trapping a body ofsaid. secondjfluid in said second cylinder to cushion said member as it'approaches the limit of said working stroke.

9. Aidevicev having a member which is advanced to perform a working stroke and which is retracted preparatory to a succeeding working stroke, said member having a chamber in which abodyofliquid-isconfined, a cylinder extending into said-chamber and spaced from the-walls thereof, stationary firstand second pistons, saidfirstpiston occupying said cylinder, a reciprocatory fiuidmotor having-a second cylinder-:connected to said" member and occupied by 'said secondpiston, a stationary tube which enters-and communicates with said second cylinder and Jaxially of which said second cylinder may slide, said first and second pistons and said tube being serially connected in axial alignment,

means for supplying a second liquid under pressure through said tube to the interior of said second cylinder to retract it and in so doing cause said first piston to compress said body of liquid, means for permitting liquid in said second cylinder to exhaust so that said body of liquid may expand to efiect said working stroke of said member, and means for trapping a body of said second liquid in said second cylinder to cushion said member as it approaches the limit of said working stroke.

10. In a press of the character described, a

ram which is advanced to perform a working stroke and which is retracted preparatory to a succeeding working stroke, said ram having a chamber in which a body of liquid is confined, a cylinder extending into said chamber and spaced from the walls thereof, stationary first and second pistons, said first piston occupying said cylinder, a fluid motor having a second cylinder connected to said ram and occupied by said second piston, means for supplying fluid under pressure to said second cylinder to retract the latter and in so doing retract said ram and cause said first piston to compress said body of liquid, means for permitting fluid in said second cylinder to exhaust so that said body of liquid may expand to effect the Working stroke of said member, and means for trapping a body of said fluid in said second cylinder to cushion said ram as it approaches the limit of said working stroke.

ROBERT F. ZUMWALT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 531,792 Forslund et al Jan. 1, 1895 786,236 Ross Mar. 28, 1905 840,877 Steedman Jan. 8, 1907 904,528 Hamilton et al. Nov. 24, 1908 1,129,964 Ebeling Mar. 2, 1915 1,268,270 Nazel June 4, 1918 1,857,624 Degenhardt May 10, 1932 1,891,312 Knecht Dec. 20, 1932 2,346,667 Dowty Apr. 18, 1944 2,560,005 Shawbrook July 10, 1951 2,563,194 Shawbrook Aug. 7, 1951 2,574,875 Lang Nov. 13, 1951 FOREIGN PATENTS Number Country Date 485,617 Great Britain May 16, 1938 OTHER REFERENCES Dow Corning Silicone Note Book, Fluid Series No. 3, issued Sept. 1948, page 27, published by Dow Corning Corp, Midland, Mich.

Images