US3252698A - Hydraulic cushion and return device for dies - Google Patents

Description

y 1966 J. v. PERRQNE 3,252,698

HYDRAULIC CUSHION AND RETURN DEVICE FOR DIES Original Filed Dec. 15, 1961 PM 2 W??? T/aj 40 INVENTOR. Jnmg l PERRONE B ,djz'lson, Seflle 8. Craig flTTO/{NEl j United States Patent 3,252,698 HYDRAULIQ CUSHION AND RETURN DEVICE FOR DIES Ilames V. Perrone, 4L1 Shady Hollow, Dearborn, Mich. Original application Dec. 15, 1961, Ser. No. 159,701, 110W Patent No. 3,171,640, dated Mar. 2, 1965. Divided and this application Dec. 16, 1964, Ser. No. 418,923

2 Claims. (Cl. 267-1) The present invention relates to a die pad control mechanism for a press and more particularly to a hydraulic control system for controlling the movement of a die pad to and from a working position in a press.

This application is a division of my copending United States application, Serial No. 159,701, filed December 15, 1961, now Patent No. 3,171,640.

In modern, high speed presses commonly utilized for performing stamping, drawing or other operations upon sheet metal, it is necessary to provide for the accurately controlled movement of the die pad normally carrying the lower of the cooperating die elements of the press. It has been proposed that this die pad be mounted upon a plurality of individual hydraulically actuated cylinder and piston assemblies and that these assemblies be controlled from a common control valve or set of control valves. The die pad conventionally contacts the pistons of the assemblies and is movable with these pistons. Upon actuation of the press to its closed or working position, the pistons are forced downwardly within the cylinder block to subject hydraulic fluid trapped beneath the piston in the cylinder block to a pressure proportional to the working pressure of the press. Upon venting of this hydraulic pressure in a controlled manner, the consequent downward displacement of the die pad during the working stroke of the press is accommodated. Upon opening of the press, i.e., usually vertical retraction of the upper die member, the hydraulic fluid is fed back into the cylinder block beneath the pistons to elevate the die pad to its initial position prior to the next subsequent working stroke of the press. In some instances, e.g., to aid in stripping complex or deeply drawn parts from the press dies, it is desirable to delay elevation of the die pad to its initia position.

Several expensive and complicated valving assemblies have been proposed for controlling the movement of the die pad, both during the working stroke of the press and during return of the die pad to its initial or starting position. Such previously proposed valving systems as have been heretofore utilized are difficult to initially install, set up and maintain during use, are expensive and complicated in construction, arrangement and installation, and are inflexible in their adaptation to the widely variant working conditions encountered in changes from one set of dies to another within a given press.

The present invention now proposes a new and novel valve structure for controlling the movement of a die pad to and from a working position in a press. Generally, the basic valve structure of the present invention includes a unit main valve body which may be used singly or in multiples to provide flexible valving arrangements ca pable of accommodating a wide variety of operating conditions at which the amount of fluid displaced and the fluid pressures encountered are widely variant. Each such main valve body is provided with an inlet element serving to control the flow of fluid into the cylinder block to displace the die pad pistons therein and a single outlet capable of controlling the operation of the inlet element so as to accommodate the flow of hydraulic fluid from a cylinder block during displacement of the die pad upon press actuation.

One fundamental advantage of the present invention resides in the utilization of the single inlet element of each valve body as the sole flow-controlling element for fluid flow both to and from the cylinder block and the utilization of the outlet element merely as a control device for the inlet element during flow of fluid in one direction only therethrough.

It is, therefore, an important object of the present invention to provide a new and novel control valve assembly for controlling movement of a die pad to and from a working position in a press.

Another important object of this invention is the provision of an improved and substantially simplified valve assembly for controlling actuation of a die pad for a press, the valve assembly including a single unit valve body or cartridge through which the flow of hydraulic fluid occurs during complete cycling of the press and which may be readily removed and replaced as a unit.

Another important object of this invention is the provision of a unitary hydraulic valve assembly particularly adapted for utilization in conjunction with a die pad control mechanism for a press and including a single valve element accommodating hydraulic fluid flow occurring upon actuation of the press die pad in either direction.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

On the drawings:

FIGURE 1 is a somewhat schematic representation of a die pad control mechanism for a press and illustrating in detail a hydraulic control valve of the present invention in a neutral or non-actuated position;

FIGURE 2 is a view similar to FIGURE 1, but illustrating the valve in an actuated position; and

FIGURE 3 is a view similar to FIGURES l and 2 but illustrating the valve in another actuated position.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

As shown on the drawings:

In FIGURE 1, reference numeral 10 refers generally to an accumulator providing a source of hydraulic fluid under pressure. The accumulator 10 may take any desired form but generally may be a cylindrical casing 11 containing .a body of hydraulic fluid, e.g., to the indicated level 12, the upper end of the casing 11 communicating with a conduit 13 connected to a source of air or similar fluid under pressure. The accumulator is connected, as through conduit 14 to a main valve block 15 having an inlet opening 16 communicating with the conduit 14 and a transverse passage 17 communicating through one or more branch passages 18 with an open-topped valve body recess 19.

Positioned within the valve body recess 19 is a main valve body 20. It will be appreciated that a number of similar, parallel valve body recesses 19 may be provided in a single valve block 21, each such recess 19 in the block 21 receiving therein a valve body 20. The number of such main valve bodies 20 provided within any given block 21 is dependent upon the fluid flow required for a given installation, and the utilization of a plurality of such valve bodies 20 permits the utilization of valve bodies of standard size and capacity under a wide variety of operating conditions.

Each such valve body establishes and controls communication between the accumulator 10 and a cylinder block 22 having therein a plurality of recesses 23 snugly receiving pistons 24 contacting the undersides of a die pad 25, in a manner well known in the art. The cylinder block recesses 23 communicate with the main valve block 21 by means of conduits 26, valve block ports 27, and valve body recesses 19 into which the main valve body 20 depends. One or more cylinder recesses 23 communicate with each main valve body port 27 so that each main valve body 20 controls the flow of hydraulic fluid between one or more cylinder recesses 23 and the accumulator 10.

The main valve body 20 is a unitary cartridge which comprises an upper, preferably hexagonal valve body head 30 overlying a threaded valve body boss 31 received by a threaded opening 32 defined in the main valve block 21. The unitary structure of main valve 20 and its location relative to valve block 21 provide a significant advantage over known prior art. The structure and location of main valve 20 allows for easy, unitary removal and replacement of valve 20 simply by unthreading at connection 32, when the valve has become worn or is in need of service. Performance of this procedure requires only a few seconds of time and thus avoids costly equipment down time. Beneath the threaded portion 31, the main valve body is provided with a plurality of ports 33 establishing communication between the inlet port 18 and the lower cylindrical valve body portion 34. This main valve body portion 34 is provided with an enlarged body recess 36 communicating through an upper valve opening 37 with the valve ports 33, the valve opening 37 being defined at the inner periphery of an annular end wall 38 defining a valve seat at the opening 37. The main valve body portion 34 is provided with radial ports 39 establishing communication between the interior opening 36 thereof and the valve block recess 19.

Disposed interiorly of the main valve body is a valve inlet element 40 having a lower cylindrical exterior surface 41 snugly mating with the inner surface 36 of the valve body 34 and merging through a frusto-conical inclined portion 42 with a reduced diameter nose portion 43 terminating at the free upper end in a frusto-conical peripheral seat 44 sealingly engageable with the valve body Wall 38 to prevent the flow of fluid through the valve aperture 37.

The lower extremity of the valve body portion 34 is recessed to receive interiorly thereof a radially extending orifice plate 45 retained in position by suitable means, as by a snap ring 46. Bottomed against the upper surface of this orifice plate 45 and confined thereby against the undersurface of the inlet element 40 is a coiled compression spring 47 urging the valve inlet element 40 upwardly, so that the tapered seat 44 seats snugly against the wall 38 to prevent the flow of fluid from the inlet ports 33 through the valve port 37.

The inlet element 40 is provided with an inwardly directed shoulder 48 circumscribing a circular valve port 49. The flow of fluid through this valve port 49 is controlled by an outlet element 50.

This valve element 50 is provided with a lower, downwardly facing frusto-conical valving surface 511 cooperable with the valve port 49 to prevent the flow of fluid therebetween. The valve element 50 is urged against the shoulder 48 into sealing relation with the port 49 by means of a coiled compression spring 52 acting upon the free upper surface 53 of the valve element and urged thereagainst by an annular snap ring or the like 54 carried by the inlet element 40. The outlet element 50 is provided, beneath the frusto-conical surface 51 thereof with a depending extremity of reduced diameter axially projecting into a freely vertically displaceable, generally cylindrical orifice pin 55. This orifice pin 55 depends freely through the central cylindrical orifice 56 of the orifice plate 45, the pin serving to keep the orifice free of any dirt or other debris which might become lodged therein.

The operation of the device is well illustrated by a comparison of FIGURES l, 2 and 3. In the neutral or nonactuated position of FIGURE 1, the die pad 25 is illustrated in its lowermost position, with the piston 24 being bottomed within the cylinder recess 23. At this position, the inlet element is displaced upwardly by the compression spring 47 to close the valve port 37 and to interrupt any communication between this valve port 37 and the radial valve ports 39. At the same time, the outlet element 50 has its conical surface 51 in sealing engagement with the shoulder 48 to interrupt flow through the valve port 49, by virtue of the coiled compression spring 52 urging the valve element 50 to its illustrated or lower position.

-In the condition of FIGURE 2, fluid from the accumulator 10 under the pressure of air or other gas in the accumulator cylinder 11 displaces fluid under pressure through the line 14, the passage 16, the transverse passage 17 and each of the inlet passages 18 for flow through the radial inlet passages 33 of the main valve body 20.

Assuming that the pressure within the accumulator and exerted upon the hydraulic fluid is on the order of 50 pounds per square inch, such pressure is sufiicient to overcome the compression force of the spring 47, and the inlet element 40 is displaced downwardly against the spring to open communication between the upper or axial valve port 37 and the lower, radial valve ports 39. The resultant flow of fluid from the accumulator through the valve block recess 28 and the port 37 enters the conduit 26 and displaces the piston 24 upwardly to thereby elevate the die pad 25 to its operating position for the next subsequent press stroke. External stops are conventionally provided for the die pad to position the die pad in its proper relation to the press and the movable die element carried thereby.

Upon actuation of the press, the die pad 25 is depressed and the piston 24 is similarly depressed to generate within the cylinder space 23 substantial hydraulic pressure. This pressure is exerted through line 26, port 27 and valve block recess 19 upon the main valve assembly. This inlet element 40 is balanced against such pressure, the pressure being vented through the orifice 56 of the plate against the entire undersurface of the inlet element 40, and the pressure being exerted in the reverse direction upon the inlet element 40 against the inclined surfaces 44 and 42 thereof by flow through ports 39. However, the pressures upon the undersurface of the inlet element 40 act against the outlet element only in opposition to the compression spring 52.

When the pressure against the chamfered or inclined face 51 of the outlet element becomes sufficient to overcome the compression force of the spring 52, the outlet element 50 is displaced upwardly, thereby opening the valve port 49. The opening of the port 49 relieves the pressure on the undersurface of the inlet element 40. As a result, the inlet element is no longer subject to balanced pressures, but to an unbalanced pressure acting on the chamfered surfaces 42 and 44 to displace the inlet element downwardly against compression spring 47. That fluid under pressure passing through the lower inlet element port 49 will, of course, flow upwardly through the hollow inlet element and through the upper radial ports 33. Upon downward displacement of the inlet element 40, the pressure will be vented through the lower radial ports 39, between the concentric spaced surfaces 36 and 43 of the valve body 34 and the inlet element 40, respectively, through the upper valve port 37 and finally through the upper radial ports 33 into the passage 18. Fluid thus displaced by the piston 24 can now flow freely through the main valve body, by virtue of opening of the inlet element through the passages 17 and 16 and the conduit 14 into the accumulator, thereby accommodating movement of the die pad 25 downwardly under the displacement force of the press. The pressure of fluid so flowing to the accumulator will be modulated by the combination of the outlet element 50 and the inlet element 40.

After the die pad 25 has reached its lowermost position because of actuation of the press, pressure will be maintained in the piston space 23 until such time as the die pad begins its upward stroke when press actuation completes its full cycle. At this time, the cycle heretofore described will be repeated.

Having thus described my invention, I claim:

1. A valve mechanism for controlling the flow of hydraulic fluid between an accumulator and a press-actuated die pad cushion cylinder, comprising a hollow cylindrical main valve body interposed between said accumulator and said cylinder, said body having a reduced diameter inlet port at one end in constant communication with said accumulator, a second port extending radially through the Wall of said Valve body intermediate the ends thereof, and a third port at the other end of said valve body, said second and third ports being in constant communication with said cylinder, a valve member having a main cylindrical section slideably received within said valve body, a reduced diameter head portion projecting axially from one end of said cylindrical section to define an annular shoulder at said one end of said cylindrical section, said head portion being engageable with said inlet port to block direct communication between said inlet port and said second port, spring means resiliently biassing said valve member toward said inlet port, means defining an axial 6 passage extending through said valve member having one end in constant communication with said inlet port and its other end in constant communication with said third port, and one-way check valve means in said axial passage permitting flow of fluid through said axial passage only in the direction from said third port to said first port.

2. A valve mechanism as defined in claim 1 further comprising a valve block having a flow passage extending 'therethrough from an inlet connected to said accumulator to an outlet connected to said cylinder, said passage having an enlarged chamber therein terminating at one end in a passage section adapted to sealingly receive said cylindrical valve body with said second and third ports opening into said chamber and said inlet port opening into said passage.

References Cited by the Examiner UNITED STATES PATENTS 1,849,691 3/1932 Rode 267-1 2,393,589 1/1946 Compton et al. 137493.6 X 2,901,238 8/1959 Williamson 267-1 FOREIGN PATENTS 777,611 12/1934 France.

ARTHUR L. LA POINT, Primary Examiner.

W. B. WILBER, Assistant Examiner.

Claims (1)

1. A VALVE MECHANISM FOR CONTROLLING THE FLOW OF HYDRAULIC FLUID BETWEEN AN ACCUMULATOR AND A PRESS-ACTUATED DIE PAD CUSHION CYLINDER, COMPRISING A HOLLOW CYLINDRICAL MAIN VALVE BODY INTERPOSED BETWEEN SAID ACCUMULATOR AND SAID CYLINDER, SAID BODY HAVING A REDUCED DIAMETER INLET PORT AT ONE END IN CONSTANT COMMUNICATION WITH SAID ACCUMULATOR, A SECOND PORT EXTENDING RADIALLY THROUGH THE WALL OF SAID VALVE BODY INTERMEDIATE THE ENDS THEREOF, AND A THIRD PORT AT THE OTHER END OF SAID VALVE BODY, SAID SECOND AND THIRD PORTS BEING IN CONSTANT COMMUNICATION WITH SAID CYLINDER, A VALVE MEMBER HAVING A MAIN CYLINDRICAL SECTION SLIDEABLY RECEIVED WITHIN SAID VALVE BODY, A REDUCED DIAMETER HEAD PORTION PROJECTING AXIALLY FROM ONE END OF SAID CYLINDRICAL SECTION TO DEFINE AN ANNULAR SHOULDER AT SAID ONE END OF SAID CYLINDRICAL SECTION, SAID HEAD PORTION BEING ENGAGEABLE WITH SAID INLET PORT TO BLOCK DIRECT COMMUNICATION BETWEEN SAID INLET PORT AND SAID SECOND PORT, SPRING MEANS RESILIENTLY BIASING SAID VALVE MEMBER TOWARD SAID INLET PORT, MEANS DEFINING AN AXIAL PASSAGE EXTENDING THROUGH SAID VALVE MEMBER HAVING ONE END IN CONSTANT COMMUNICATION WITH SAID INLET PORT AND ITS OTHER END IN CONSTANT COMMUNICATION WITH SAID THIRD PORT, AND ONE-WAY CHECK VALVE MEANS IN SAID AXIAL PASSAGE PERMITTING FLOW OF FLUID THROUGH SAID AXIAL PASSASGE ONLY IN THE DIRECTION FROM SAID THIRD PORT TO SAID FIRST PORT.

Images