US3522939A - Metal working press cushion structure - Google Patents

Description

1970 F. J. RODE 3,522,939

METAL WORKING PRESS CUSHION STRUCTURE Filed Oct. 2, 1967 2 Sheets-Sheet 1 FIG! INVENTOR FREDRIICH J. RODE ATTORNEYS g- 1970 F. J. RODE METAL WORKING PRESS CUSHION STRUCTURE 2 Sheets-Sheet 2 Filed Oct.

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INJENT OR FREDRICH J. RODE WW ATTORNEYS United States Patent Oflice 3,522,939 Patented Aug. 4, 1970 US. Cl. 267-119 8 Claims ABSTRACT OF THE DISCLOSURE Structure for cushioning a blank holder or the like on a press with pressure at different locations thereon without regard to minor irregularities in blanks held thereby. The specific structure disclosed includes four separate hydraulic cushions for applying pressure to the blank holder at four corners of a rectangle defined by the cushions. An additional hydraulic cushion is disclosed, movable to different locations within the rectangle defined by the four hydraulic cushions to further alter the pressure pattern on the blank holder. The cushions are each connected to separate control systems for maintaining predetermined pressures in the cushions as the press is operated.

BACKGROUND OF THE INVENTION Field of the invention The invention relates to cushions for use with metal working presses and refers more specifically to hydraulic cushion structure for providing individually selected cushion pressures at selected locations on a blank holder or the like.

DESCRIPTION OF THE PRIOR ART In the past, blank holders used in double action presses and the like have often been positioned by a screw and nut arrangement at the four corners thereof so that they provide uniform or desired non-uniform pressures on metal blanks engaged thereby. Such structure must be adjusted accurately to provide a desired pressure. In addition, since the usual blanks may have individual dimensional irregularities therein, such as varied thickness, to provide desired pressure at desired points on a blank holder during operation of a press, a separate adjustment might need to be made for each blank with the prior nut and screw adjusting structure. Individual adjusting of the nut and screw structures of the past to provide the different holding pressures desired is time consuming, tedius and inefiicient.

SUMMARY OF THE INVENTION The invention is in providing structure for maintaining separate pressures at different locations on a single blank holder or the like, which pressures are the same regardless of minor dimensional irregularities in successive blanks and at least some of which positions may be varied.

More specifically, hydraulic cushions are provided to support a blank holder at the four corners of a rectangle defined by the hydraulic cushions. The hydraulic cushions are each controlled by a separate pressure control system for providing a pressure in each hydraulic cushion.

The pressure control systems each include means for maintaining the cushion associated therewith under predetermined tank pressure. Piloted means are provided for relieving the associated cushion after a predetermined pressure has been built up in the associated cushion.

In addition, at least one cushion may be provided for movement into different locations relative to the other hydraulic cushions to provide additional cushioning pressure at a desired location on the blank holder.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation view of a single acting metal working press including cushion structure constructed in accordance with the invention.

FIG. 2 is an enlarged partial section view of the press structure illustrated in FIG. 1, taken substantially on line 22 in FIG. 1 with the bolster plate and die structure removed therefrom.

FIG. 3 is a partial section view of the structure illustrated in FIG. 2, taken substantially on line 3-3 in FIG. 2, with the die structure and bolster plate of FIG. 1 included and partially broken away.

DESCRIPTION OF THE PREFERRED EMBODIMENT.

The press structure 10 illustrated in FIG. 1 includes the base 12 which may be conveniently secured to a floor 14 by, for example, frame members 16 or the like and bolts 18 passing through slots 20 in the base 12.

The press 10 further includes the frame 22 supporting the crank shaft 24 in bearings 26. The press drive wheels 28 are secured to the crank shaft 24 at the ends thereof and are driven by, for example, the pinions 30 in mesh therewith and rotated by convenient means, such as an electric motor (not shown) through the drive shaft 32.

The cranks 34 are secured to the crank shaft 24 for reciprocal movement on rotation of the crank shaft 24 and support the upper platen 36 for reciprocal movement in the guides 38 which are secured to the frame 22. An upper die or dies 40 may be secured to the platen 36 by convenient means (not shown).

Such press structure is common and will not therefore be considered in further detail at this time. The press structure 10 illustrated in FIG. 1 further has openings 42 extending through the base 12 on opposite sides of the center line thereof into which the cushion structures 44 for supporting blank holders 46 or the like of die structures 48 are positioned.

- The cushion structures 44, as best shown in FIGS. 2 and 3, include the rods 50 supported from the frame projections 52 and secured thereto by the bolts 54. The bottom plates 56 are similarly secured to the rods 50 by bolts 58 in conjunction with the annular abutment surfaces 60 on the rods 50. The top plate 62 is slidably mounted on the rods 50 in the bearing sleeves 64 and a pin casting 66 is supported for reciprocal movement on the rods 50 in the bearing sleeves 68 and 70. The pin casting 66 sets on and moves with the top plate 62.

Top plate 62 is supported on the hydraulic cushions 72 positioned adjacent the four corners of the top plate 62. Each of the cushions 72 include a piston 74 and cylinder 76 in which the piston 74 is mounted for reciprocal movement. The cushions 72 define a rectangle therebetween and support the top plate 62 in variable position above the bottom plate 56 between the piston extended position illustrated in FIG. 3 and a piston retracted position in Which the top plate 62 and pin casting 66 are lowered in FIG. 3 to permit downward travel of the pins and blank holder 46 supported thereby, as will be further considered subsequently.

The position of the piston 74 in the cushion 72 depends upon the pressure applied in the cylinder 76 through the associated pressure control system 78 and the pressure applied in the cylinder 76 through the pin casting 66 and the pins 80 from the blank holder 46. Thus the pressure which can be exerted on any corner of the top plate 62 and thus on any corner of the blank holder 46 may be varied in accordance with the relief pressure setting of a particular pressure control system 78. The corner pres- 3 sures may be varied to supply a pressure required for a particular pressure pattern on the blank holder 46.

Conversely the relief pressure of the individual pressure control systems 78 may be set at one selected value for all of the four corner cushions 72 and exactly the same fixed pressure will be provided on blanks held by the blank holder 46 regardless of minor irregularities in the blanks since, after the hydraulic cushions 72 have supported a particular load, no more pressure will be sustained thereby during downward movement of the blank holder 46.

In addition at least one additional hydraulic cushion 82 is provided operable between the bottom plate 56 and top plate 62 which may be moved into different selected locations beneath the top plate 62 to provide special pressure patterns on the top plate 62 and thus on the blank holder 46, as required in the particular die structure 48. As shown, the cushion structure 82 may be moved in a circular path defined in bottom plate 56 by a circular T-slot 84 and locked in position on the circular path by convenient means, such as locking bolts 86.

A separate cylinder 88 including a piston (not shown) reciprocally mounted therein and a piston rod 90 connected to the piston and extending out of the cylinder 88 is positioned between the bottom plate 56 and top plate 62. The function of the cylinder 88, piston therein and piston rod 90 which may be pneumatically operated is to return the top plate 62 to the position shown in FIG. 3 and thus aid in stripping a part formed in the die structure 48, as will be evident to those in the art.

The die structure 48 includes the bolster plate 92 secured on the press bed '94 by convenient means (not shown) and a die 96 secured to the bolster plate 92 including a blank cutting portion 98 and a portion 100 over which the blank is formed. The die structure 48 further includes the blank holder 46 previously mentioned and the pins 80 for transferring pressure from the pin casting 66 to the blank holder 46.

The hydraulic control systems 78 each include a tank of hydraulic fluid 102 having hydraulic fluid under a rather light pressure of, for example, 100 lbs. p.s.i. regulated by the regulator 106. The tank 102 is connected through conduits 108 and 110 to one of the cushions 72 through the check valve 112 through which fluid under light pressure in the tank 102 is permitted to flow to the cushion 72. A pressure relief valve 114 is placed in parallel with the check valve 112 and permits reverse flow of hydraulic fluid from the cushions 72 through the pressure relief valve to the tank 102 when the hydraulic pressure in the cushion 72 is at or exceeds the pressure setting of the pressure relief valve 114. The pressure relief valve 114 is operably associated with the pilot valve 116 to permit rapid passage of hydraulic fluid from the cushion structure 72 to the tank 102 once the pressure in the cylinder 72 is at the critical opening pressure of the pressure relief valve 114.

A separate pressure control system 78 is provided for each of the cushions 72 at the four corners of the upper plate 62 and for the additional cushion 82 provided. Thus the pressure at the 4 corners of the upper plate 62 and therefore on the blank holder 46 through the pins 80 and pin casting 66 may be individually controlled along with individual control of the additional cushion 82.

Thus in overall operation before a metal blank is formed on the die structure 48 by the press 10, the sepa rate pressure relief valves 114 of the pressure control systems 78 are set at selected pressures at which it is desired to maintain the pressure at selected locations on the blank holder 46. If the additional cushion 82 is provided, the. pressure relief valve 114 associated with the additional cushion is also set to a predetermined pressure and the cushion 82 is moved into the desired location therefor under the top plate 62 to provide the desired pressure pattern on the blank holder 46.

The blank is then placed on the die structure 48 and the press 10 is operated in the usual manner. On operation of the press 10 the blank holder 46 will be forced downward due to engagement with the blank which is in turn forced downward by the corresponding parts of the top die 40. Downward movement of the blank holder 46 causes the pins 80 to apply pressure to the pin casting 66 which in turn applies pressure to the top plate 62 so that the pressure on the blank holder 46 is passed to the cushions 72 and 82. When the pressure in the cushions 72 and 82 reach the pressure set on the pressure relief valves 114 which will provide the desired pressure pattern for the blank holder 46, the piston portions of the cushions 72 and 82 telescope into the cylinder portions thereof to permit downward movement of the blank holder 46 and forming of the blank over the portion 100 of the die 96.

After the blank has been formed in the die structure 48 and the cranks 34 have moved into their upper position Withdrawing the die 40 from engagement with the die structure 48, the pistons of the cushions 72 and 82 are returned to the position illustrated in FIG. 3 by hydraulic fluid from the tanks 102 passing through the check valves 112 of the pressure control systems 78. The movement of the top plate 62 back to the position illustrated in FIG. 3 is aided by the cylinder, piston and piston rod structure 88 and 90. The movement of the top plate 62 back into the position shown in FIG. 3 will cause stripping of a formed blank from the die structure 48 on movement of the pin casting 66, pins 80 and blank holder 46 back into the position shown in FIG. 3.

Should subsequent blanks having minor dimensional irregularities therein be formed on the die structure 48, the blank holder 46 will provide the same holding pressures since the cushions 72 and 82 recognize only the pres sure applied thereagainst rather than any dimensional irregularities in the blank positioned on the blank holder 46. In addition if it is desired to provide a different holding pressure pattern on subsequent blanks positioned on the die structure 48, the pressure pattern on the blank holder 46 may be altered as desired by simply adjusting the pressure relief valves 114 of the cushions 72 or 82 and/ or moving the cushion 82.

While one embodiment of the present invention has been disclosed in detail, it will be understood that other embodiments and modifications thereof are contemplated by the inventor. It is the intention to include all embodiments and modifications as are defined by the appended claims within the scope of the invention.

What I claim as my invention is:

1. Structure for cushioning a blank holder on a metal working press or the like comprising a plurality of sep arate cushions engaged with the blank holder at different locations thereon, at least one of which cushions is movable to selected locations on the blank holder, and a separate pressure control system connected to each cushion for separately regulating the pressure applied to the blank holder at the different locations on actuation of the press.

2. Structure as set forth in claim 1 wherein the difierent locations on the blank holder are at the corners of a rectangle.

3. Structure as set forth in claim 2 wherein the cushions are hydraulic.

4. Structure as set forth in claim 3 wherein the separate pressure control systems each include a tank of hy draulic fluid under pressure, a conduit connected between the tank and associated cushion, a check valve in the conduit permitting fluid flow only toward the associated cushion from the tank and a pressure relief valve extending around the check valve for permitting fluid flow from the associated cushion to the tank only after a selected pressure is developed in the associated cushion.

5. Structure as set forth in claim 4 and further including a pilot valve operably associated with the pressure relief valve in each pressure control system to improve the response of and fluid flow through the pressure relief valve.

6. Structureas set forth in claim 1 and further including a plurality of pins supporting the blank holder, a pin casting supporting the pins, a top plate supporting the pin casting, a bottom plate rigidly supported in a position be low the top plate and wherein the cushions include four piston and cylinder structures positioned between the top plate and bottom plate at the corners thereof defining a rectangle.

7. Structure for cushioning a blank holder on a metal working press or the like comprising a plurality of pins supporting the blank holder, a pin casting supporting the pins, a top plate supporting the pin casting, a bottom plate rigidly supported in a position below the top plate, four piston and cylinder structures positioned between the top plate and bottom plate at the corners thereof defining a rectangle, at least one additional piston and cylinder cushion extending between the top plate and bottom plate, means for moving the additional cushion to selected locations within the rectangle defined by the other four cushions including a circular inverted T slot in the bottom plate having its center at the center of the defined rectangle, means for locking the additional cushion in selected locations along the slot and a separate pressure control system connected to each cushion for separately regulating the pressure applied to the blank holder at the different locations on actuation of the press.

8. Structure for cushioning a blank holder on a metal working press or the like comprising a plurality of pins supporting the blank holder, a pin casting supporting the pins, a top plate supporting the pin casting, a bottom plate rigidly supported in a position below the top plate, four piston and cylinder structures positioned between the top plate and bottom plate at the corners thereof defining a rectangle, at least one additional piston and cylinder cushion extending between the top plate and bottom plate, means for moving the additional cushion to selected locations within the rectangle defined by the other four cushions, and a separate pressure control system connected to each cushion for separately regulating the pressure applied to the blank holder at the ditferent locations on actuation of the press, each including a separate tank having hydraulic fluid under pressure associated with each cushion, a conduit connecting each separate tank and associated cushion, a check valve in each conduit for allowing fluid flow only toward the associated cushion from the tank and a separate pressure relief valve in parallel with each check valve for allowing fluid flow back toward the tank from the associated cushion in response to selected pressure in the cushion and a separate pilot valve operably associated with each pressure relief valve.

References Cited UNITED STATES PATENTS 7/1924 Nelson. 10/1930 Rode.

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