US1745549A - Die cushion - Google Patents

Description

Feb. 4;, 1930.

s. MARGHITAN DIE CUSHION Filed Feb. 16, 1928 2 Sheets-Sheet 1 Feb. 4, 1930. s. MARGHITAN 1,745,549

DIE cU'sHIoN Filed Feb. 16. 192e 2 sheets-sneer 2 -work or entirely eliminating same.

Patented Feb. 4, 1930 UNITED STATES PATENT OFFICE SAMUEL MARGHITAN, 0F CHICAGO, ILLINOIS,

ASSIGNOR TO NEL-MAR MFG. CO., OF

CHICAGO, ILLINOIS, A CORPORATION '0F ILLINOIS DIE CUSHION Application led February 16, 1928.V Serial No. 254,730.

- by the ram during bending, forming or drawlng operations. There are many situations where the desideratum is to obtain a maximur amount of resistance, against the work, during a portion of the down stroke of the ram, and at some place or places during the stroke, to reduce or increase the amount of resistance, more or less, andfin some cases it is highly desirable that the amount of resistance vary at several places during the working stroke of the ram.

In many press operations'it is essential that the Work be firmly gripped between the dies or between one die and the draw ring, during the'entirestroke of the ram, and in many drawing operations it is necessary that the grip on the Work be released gradually or suddenly at spaced intervals as the ram makes its down stroke, and one of the objects of the present invention is to provide automatic means for varying the amount or degree of resistance offered against the pressure exerted by the ram While performin its nother object is to provide means whereby the` variable pressure or resistance may be regu' lated or eliminated to suit the particular character of work at hand.

Other objects and advantages willi occur in the courseof this specification, and with said objects and advantages in view, this invention consists fin a die cushion having means whereby the resistance or pressure against the ram is capable of variation during the working stroke of the ram. It further consists in a die cushion in which the variable pressures may be regulated to suit ythe particular work at hand. It further consists in a die cushion in which the resistancey or pressure against the ram may vary during the down stroke of the ram either through a gradual variation or through sudden changes from a maximum' pressure to a reduced pressure. The invention further consists in the several novel features hereinafter fully set forth and claimed.

The invention is clearly illustrated in the drawings accompanying this specification in which- Figure.K 1 is a central vertical section through a""fragment of a power press and' showing a simple embodiment of the present invention applied thereto;

Fig. 2 is a View similar to Fig. l with certain parts broken away, the operating mechanism being illustrated in a different position and the parts being shown upon a larger scale;

Fig.3 is a detail horizontal section taken on the line 3-3 of Fig. 2; and

Fig. 4 is a detail side elevation of a slightly modilied form of cani which forms part of the present invention.

Referring to said drawings, which illustrate one embodiment of the present invention, the reference character 5 designates a fragment of the frame of a power press having the usual uprights or standards 6 on which is guided the ram or plunger 7 as is customary. n On the frame of the press is supported the usual bolster 8 on which is mounted a die shoe 9 carrying the lower die 10. The upper die 11 is mounted on the ram as usual. As is well understood, power mechanism is provided inthe press for reciprocating the ram, but as this forms no part of the present invention, the power mechanism has not been illustrated.

In connection with certain drawing operations, a draw ring 12 is provided, which surrounds the lower die 1() and is adapted to engage with that part of the underside of the blank 13 which projects beyond the lower die 10. In some cases a` cushion pad is emplo ed for certain classes of work, as iswell un erstood. The draw ring or cushion pad is yieldingly supported by lelements of the die cushion, which forms the subject matter of the present application, and, as shown, the draw ring is mounted upon a number of draw pins 14 which project down through holes in the bolster 8 and are secured to and supported by a plate or block 15 that is mounted upon a piston rod 16 which has a piston or plunger 17 upon its lower end which is contained in the-cylinder 18 of the die cushion.

The cylinder 18 is closed at both ends by cylinder heads and 23 and may be supported from the-bolster by rods 19 which are secured in the bolster and are connected to the cylinder head 20 by nuts 21. The cylinder 18 may be flanged upon its lower end and secured to the cylinder head 20 by bolts 22. Suitable packing is provided between the cylinder 18 and head 20 to insure a tight joint therebetween. The upper head of the cylinder may comprise an end wall 23 formed as a part of the cylinder` Leading from the cylinder, at one side of the piston 17, is a conduit 24, which also communicates with the cylinder on the opposite side of the piston and forms a fluid passage around the piston. It will be understood that the cylinder is filled or partially filled with a fluid, such as liquid or compressed airor the like, and during the down stroke of the piston the fluid is forced through said conduit from the lower side of said piston to the upper side thereof. Interposed in said conduit is a pressure regulating valve 25 or relief valve having regulatable means whereby the flow of the fluid through said valve may be governed.

lVhile the exact form of pressure regulating valve or relief valve is not material to the present invention, broadly speaking, it usually embodies a compression spring 26 behind the valve proper 27,' which spring op'- erates to hold the valve seated against a pressure up to a predetermined point, and yields under pressure in excess thereof, the pressure required to compress thev valve spring determining the flow4 of fluid therethrough. By properly adjusting the valve 25, the diel cushion is made to resist a maximum or mini.- mum amount of pressure exerted by the ram during the stroke so as to afford a maximum or minimum .grip on the work operated upon which may be varied as required.

In order to provide lfor a multiple pressure or resistance to the ram, while moving through its working stroke, the piston 17 is provided with a by-pass or fluid paageway 28 extending between its opposite sides, which by-pass or passageway may be closed during a portion of the down stroke of the ram so as to provide a maximum amount ofresistance to the under side of the piston during such portion of the stroke of the ram, and-which by-pass or passagewayis arranged tobe opened at predetermined places along the stroke of the ram to thereby permit the fluid contained in the lower end of the cylinder to rapidly escape into. the upper end thereof; Means are also provided in connection with said bypass or passageway 28 to regulate or control the flow of liquid therethrough in orderto obtain the required pressure or resistance in the die cushion. These means will now be described.

The piston stem `16y is'made hollow, asA

formed on the lower side of the cylinder head 20, whereby it may be raised or lowered to locate the grooves 30 and 3l at various positions along the axis of the cylinder 18. Conveniently, the rod 29 may be screw threaded as at 33 and threadedly connected with the boss 32, and it may be provided with a squared o1' non-circular end 34 for the reception of a wrench or other tool for adjusting the rod. A lock nut 35 may be secured upon the threaded portion of the rod 29 below the boss 32. The by-pass or passageway 28 opens downwards from the lower face of the piston 17 and its upper end extends radially to and beyond the valve device 29, where in certain positions of the pistou, the by-pass is closed by the valve device. The passageway opens upwardly at its end into the upper end of the cylinder and preferably through a pressure regulating valve or relief valve 36 secured in the upper side of the Diston.

As has been explained, the valve device 29 fits in the bore of the piston stem 16 and closes the passage through said by-pass 28, as is clearly seen in the drawings. When, however, one ofthe circumferentialgrooves 3() or 31 registers with the by-pass 28communi cation is established between the lower end of the cylinder 18 and its upper end through said by-pass, thereby permitting fluid in the lower end of the cylinder to pass more freely to the upper end of the cylinder.

The relief valve 36 may be omitted er1- tirely, if desired, whereby when the passage" way through the by-pass 28 is opened by the valve device 29, the fluid may flow unrestricted through said passageway, but with certain classes of work, it may be found desirable to control or regulate the flow of fluid through the by-pass, and, for this reason, the relief valve 36 is provided in or at the end of said by-pass. The relief valve has regulating means whereby it remains closed against pressure up to a predetermined amount and is opened when subjected to the influence of pressure above said predetermined amount, and it has adjustment means for determining the amount of. pressure required to open it, which means is usually 'controlled from a stem 37 which is accessiblev from the exterior of the cylinder.` For instance, an opening may be provided in the upper head 23 of the cylinder through which a socket wrench may be inserted for engage ment. with the adjusting stem 37 and said opening may closed by aplug threadedly los l secured in the cylinder head. By properly sion between the setting the relief valve 36, it will remain closed until the pressure in the lower end of the cylinder unseats the valve, whereupon the fluid is permitted to pass through the bypass 28 at a predetermined velocity.

In .order to permit the piston to return rapidly during the up stroke of the ram, ports or passa eways 38 are provided through the piston 17, which ports or passageways are arranged to be closed on the underside of the piston by a valve member 39, here shown as surrounding the lower end of the piston stem 16, and spring pressed against the lower face of the piston by a coiled compression spring 40 confined between the valve member 39 and a' nut 41 threadedly secured on the lower end of the piston stem 16. The valve -member 39 is kept closed during the down stroke of the piston 17, Idue to the pressure on the fluid, but opens to permit the fiuid to freely pass through the ports 38 during the up stroke of the piston.

It is understood that the piston 17 is forced down4 upon the fluid, contained in the lower part of the cylinder 18, by the ram on its working stroke. Means are provided for returnin the piston and the parts connected therewlthto their upper position, while the ram is vreturning to the top of its stroke.

-Said means may be in the form of coiled compression springs interposed between the plate 15 and some stationary part, and, in the drawing, a coiled compression spring 42 is shown which is confined under compreshead 23.

17 and plate 15, and one of such rods is illus-A In addition to the spring 42, or as a separate means for positively returning the piston 17 to its upper posltion, a plurality of connecting rods may be provided between some movable part, as, for instance, the ram trated at 43. Its upper end is connected to a lug 44 on the ram anditslower end extends through a lug 45 on the plate '15 and has a coiled compression spring 46 interposed between the lower side of the lug 45 and a nut 47 threaded on the lower end of the rod. 43.

When the rods 43 are employed for raising the piston and other parts supported by the plate 15, the rods 43 lift theplatey 15 while the ram'is moving to the upper vend of its stroke and the springs 46 are provided to allow of lost motion between the rods 43 and the plate 15 in case the length of travel of the ram is slightly greater than that of the plate l15.

plate 15 and the cylinder asmuch as the through the valve 25. In the simple form of means illustrated, the valve stem of the valve proper 27 has a part 48 which projects out through the casing of the valve 25 and rides ulpon a cam 49 which, as shown, is rotatab y mounted upon a bracket 50 and is operatively connected to the plate 15, as, for instance, by a link 51, a lever 52, and a rod 53.

The link 51 is connected to' an arm 54 which supports the cam 49, and the other end of the vlink is connected to one arm of the lever 52.

The rod 53 is connected to the other arm of said lever and to a 1ug55 on the plate 15. The cam 49 may be formed with a circular` cam face 56 which is eccentric with respect to the axis around which the camy rotates, and the cam is adjustable with respect to its supporting arm 54, an adjusting screw 57 being provided in the arm and engaging with the cam.

, By turning the adjusting screw 57 the relation between the circular cam face 56-and the axis of rotation of the cam may be varied so as to obtain any desired action of the cam on the valve stem. By lengthening or shortening the radius of the circular cam face 56 and by adjusting the cam, a variety of actions may be had upon the valve 27, with the result f that the pressure in the lower endv of the cylinder 18 may vary constantly during the entire working stroke of the ram. For instance, the pressure may be so regulated that the blank, to be operated upon, 'willbe tightly gripped between the upper die and the opposition part below it, and during the working stroke of the ram the grip may be lessened and again increased,v or the cam may be so set that at the commencement of the working stroke, the grip will not be so great, but during the course of the stroke the pressure will be increased, or the cam may be so set that at first the grip will not be so great, but during the course of the stroke the pressure will be increased and the grip tightened and later on reduced again. In'Fig. 4 is illustrated a slightly modified cam 49, this cam having an irregular cam face 56a whereby variable pressures may be obtained in the cylinder.

In the operation of the die cushion, the piston is normally held in its upper position with the draw ring or pressure pad heldin its upper the draw ring or pressure pad, the ram-is started on its working stroke and as the upper die encounters the blank, the blank is pressed against the draw ring or pressure pad and is gripped firml between said parts inownward pressure of the ram is opposed by the fluid contained below the piston 17 in the cylinder 18. As the ram continues its downward movement, the piston 17 is forced downward through its connections with the draw ring or fpressure pady and the fluid in the lower end o the cylinder is forced outward through' the restricted position. The blank being laid upon openin in the pressure regulating valve and is ischarged into the upper end of the cylinder 18.

When the by-pass or passageway 28 registers with a circumferential groove in the valve device 29 communication is established directly between the lower end of the cylinder and the upper end thereof through said-bypass and the fluid is permitted to flow morefreely from the lower end of the cylinder to the upper end thereof, whereby the resistance l or pressure in the lower end in the cylinder is decreased, and consequently the pressure of the die upon that part of the blank gripped between it and the draw ring or pressurel ad is released somewhat depending upon the ow of fluid through the by-pass 28. The reduced pressure remains until the by-pass 28 is again covered by the valve device, whereupon the maximum pressure is again maintained.

As has been explained, the cam actuatedpressure regulating device in the conduit 24 may operate in conjunction with the by-pass` in the piston or independently thereof, or the grip on the blank may be controlled by the action of the cam on the valve 25.

More or less variation of the exact details of construction is ossible without departing `from the spirit o this invention; I desire, 30 therefore, not to limit myself to the exact form of the construction shown and described,l but intend, in the following claims, to point out all of the invention disclosed herein. c

I claim as new, and desire to secure by Letters Patent:

1. In a die cushion for power resses, the combination of a cylinder adapte to contain fluid and closed at both ends, a piston therein, a conduit having a continuous passageway therethrough connecting one end of the cylinder with the other and having a restricted orifice whereby fluid may continuously flow 2 from the lower side of the piston to the upper '45' side thereof lwhen the piston is depressed,

- press operated means for displacingA the fluid in the cylinder, a closed passage through the piston, means controlled by the downward movement of the piston for openin said last '3' mentioned passage whereby the pressure below the pistn may be decreased at a predetermined point in the working stroke of the piston, and a second valve controlled passage through the piston through which the uid ,may pass from the up r side of the piston to the lower side thereo 'when the piston is being raised.

2. In a die cushion for power presses, the combination of acylinder adapted to contain 6 .a fluid and closed at both ends, a piston therein, a conduit having a continuous passage# 'way therethrough connecting thelower end ofthe cylinder with the upper end and hav- -ing a restricted orifice therein whereby the fluid may flow from the lower side. pf the is being raised, and press operated means for displacing the fiuid in the cylinder.

' 3. In a die cushion for power presses, the combination of a cylinder adapted to contain a fluid and closed at both ends, a piston therein, a conduit having a continuously open passageway connecting the lower end of the cylinder with the upper end and having a restricted orifice therein whereby Huid may flow from one side of the piston to the other when the piston is depressed, said piston having-a restricted passageway therethrough leading /from one side thereof to the other, a pressure operated relief valve in said restricted passageway of the piston, a valve device extending through said piston and having means for opening and closing the restricted passageway therethrough on the working stroke of the piston, a second passageway through the piston, a valve closing said last mentioned passageway and arranged to open on the up stroke of the piston, and press operated means for displacing the liuid in the cylinder.

4. In a die cushion for power presses, the combination of a cylinder yadapted to contain a fluid and closed at both ends, a piston therein, a conduit having a continuous passageway connecting-the lower end of the cylinder with the upper end and having a regulatableA restricted orifice therein whereby the fluid may flow from thelower side of the piston to the other when the piston is depressed, said piston having a controllable restricted passageway therethrough, a stationary valve devlce extending through said iston and having means for opening and c osing the passageway therein on the working stroke of the piston, a second passageway through the piston, a valve closing said last mentionedv passageway and\arr'anged to open on the upstroke of the piston, and press operated means for displacing the uid in the cylinder.

5. In a die cushion for power resses, the combination of a cylinder adapte to contain a fluid ,and closed at both ends, a piston therein, a conduit having a continuous passageway connecting the lower end of the cylinder wit the upper end thereof, a pressure re valve in said conduit, said piston havmg a restricted passageway therein extending from one side of the piston to the other, a valve device extending through said piston and cooperating therewth to open and close said restricted passageway vin the piston on the workating 1-25 ing stroke of the piston, a second passageway through the piston, a valve closing said last mentioned passageway and arranged to open on the up stroke of the piston, and press operated means for forcing said iston against the fluid contained in the cylin4 er.

6. In a die cushion. for power presses, the combination of a cylinder adapted to contain a fluid and closed at both ends, a piston therein having a restricted passageway extending from one 'side of the piston to the other, a valve device extending through said Vpiston and co-operating therewith to open and close said restricted passageway in the piston on the working stroke of the plston, a second passageway through the piston, a valve closing said last mentioned passagewa and arranged to open on the up stroke of the piston,

- a' conduit having a continuous passageway leading from one end of the cylinder to the other, a pressure regulating valve l'in said p conduit, said valve having a pressure regulating adjustment stem,v press operated means for moving said piston against the fluid in the cylinder, and means actuated bly;

said press operated means co-operating wit c said valve stem to control the passage of fluid therethrou h.

7. In a ie cushion for power presses, the combination of a cylinder adapted to contain a fluid and closed at both ends, a piston therein having a controllable restricted passageway therethrough, a conduit having a continuous passageway leading from one end of the c linder to the other and having a regulata le restricted orifice therein, ress operated means for moving said iston against the fluid, and yielding means or returning the piston to its normal position.

8. In a die cushion for power presses, the combination of a cylinder adapted to'contain a fluid and closed at both ends, a iston therein having a controllable restricte passageway leading therethrough, a conduit having a continuous passageway leading from one end of the cylinder to the other and having a regulat'able restricted orifice therein, press operated means for moving said piston against the fluid, and yielding means connected to said press operated means for returning said piston to its normal position.

9. In a die cushion for ower presses, the combination of a cylinder c osed at both ends, a piston therein, a hollow piston stem, draw ring supporting elements carried by said iston stem, there being a. passageway lea n through said piston from side to side, an a valve device ittin in the hollow of said pistonV stem and having a part arranged to close said passageway and a circumferential groove adapted to register with said passageway, whereby the passageway through said piston is opened. I

10. In a die cushion for power presses, the combination of a cylinder, a piston therein,

dult leading fromA one end of the cylinder to the other and having a restricted orifice therein.

1l. In a die cushion for power presses, the combination of a cylinder, a piston therein, a hollow piston stem, draw ring supporting elements carried by saidpiston stein, there bein a passageway leading through said piston rom side to side, and a valve device adjustably mounted in -saidhollow piston stem and having a part closing said passageway, and a passageway adapted to register with said passageway, whereby the passageway throu h said piston is opened.

12. n a die cushion for power presses, the combination of a cylinder, a piston therein having a passageway leadin therethrough from side to side, a relief va ve in said passageway, a hollow piston stem secured to said piston, draw ring pins connected to said piston stem, and a valve device mounted in the hollow of said piston stem for closing the passageway through said piston, said valve device havin a cut away portion adapted to re 'ster with said assageway to thereby estab ish communication between the opposite sides of the iston.

S'MUEL MARGHITAN.

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