US3357218A

US3357218A - Hydraulic press

Info

Publication number: US3357218A
Application number: US434810A
Authority: US
Inventors: Charles L Mitchell
Original assignee: Cincinnati Milling Machine Co
Current assignee: Milacron Inc
Priority date: 1965-02-24
Filing date: 1965-02-24
Publication date: 1967-12-12
Anticipated expiration: 1984-12-12

Description

Dec. 12, 1967 c. L. MITCHELL 3,357,218

HYDRAULIC PRESS Filed Feb. 24, 1965 7 Sheets-Sheet i Fig. 1

INVENTOR.

WW, 3 W

ATTORNEYS CHARLES L. MITCHELL 1967 c. L. MITCHELL 3,

v HYDRAULIC PRESS Filed Feb. 24, 1965 Fig. 2

i i v v 7 Sheets-Sheet 2 1967 c. L. MITCHELL 3,3

HYDRAULIC PRESS Filed Feb. 24, 1965 7 Sheets-Sheet 4 Dec. 32, 1967 c. L. MITCHELL 3,

HYDRAULIC PRESS Filed F81). 24, 1965 7 Sheets-Sheet 6 ETSLRB ZLSL 2 L l @R 5w 5 N V R :IIBLSLRB wsms evm Dec. 12, 1967 c. L. MITCHELL 3,357,218

HYDRAULIC PRESS Filed Feb. 24, 1965 7 Sheets-Sheet i5VR5 510 IlSLRg 6LS1 N Fi sci ILSEIO I @VRS 514 j I l/ United States Patent 3,357,218 HYDRAULIC PRESS Charles L. Mitchell, Cincinnati, Ohio, assignor to The Cincinnati Milling Machine Co., Cincinnati, Ohio, a corporation of Ohio Filed Feb. 24, 1965, Ser. No. 434,810 19 Claims. (Cl. 72-28) ABSTRACT OF THE DISKILOSURE A chamber pressure control apparatus for a hydraulic forming press using a series of pre-set pneumatic valves actuated by limit switches at certain points of the draw to control the chamber pressure at those points. A selector switch renders certain limit switches inactive and, as a result, the operator may select the preciseness of control during the draw.

The present invention relates to a hydraulic press of the type having a fluid pressure chamber behind a flexible diaphragm and, more particularly, to the control of the pressure in the fluid pressure chamber.

In one type of hydraulic press, a male die plunger presses a workpiece blank into a flexible diaphragm which defines a female die. Pressure in a fluid pressure chamber behind the flexible diaphragm forces the diaphragm and the workpiece blank received between the diaphragm and the plunger) around the plunger to form the workpiece blank into the shape of the plunger. It is desirable, for the most satisfactory forming, to vary the pressure in the pressure chamber as the plunger advances during the operation. This pressure chamber control is conventionally achieved by means of a cam connected to or geared to the plunger, the cam operating a hydraulic valve which controls the pressure in the pressure chamber.

A cam of the precise shape required to produce the desired pressure cycle during the formation of the workpiece is diflicult to produce. Moreover, since the cam produces a continuous signal, or command, for the control of the pressure in the pressure chamber, abrupt changes in pressure during the cycle, which may be desired for a particular workpiece, are diflicult to execute because cam operation of the valve is awkward or impossible if abrupt slopes are present on the cam.

In accordance with the present invention, the pressure in the pressure chamber is regulated, not by a continuous command as a cam would produce, but instead is regulated by a series of discrete commands. Unlike the continuous signal produced by the cam, the discrete signals of the present invention can produce abrupt changes in pressure chamber pressure. In brief, in the preferred embodiment of the invention, a plurality of pressure regulating valves are provided, each valve being set to produce a particular pressure different from the pressure produced by the other pressure regulating valves. The output pressure of these valves are normally ineffective to influence the pressure in the pressure chamber. A plurality of limit switches, one for each pressure regulating valve, are mounted in closely spaced relation for operation as the plunger advances. As the plunger advances and the limit switches are successively operated, the output of the pressure regulating valves are rendered effective successively to establish the pressure in the pressure chamber. Since successive pressure regulating valves can be set to produce widely different output pressures, a small movement of the plunger can produce a large increase (or decrease) in the pressure in the pressure chamber if desired. Moreover, the regulating valves can be easily set, or changed, to produce any desired pressure cycle.

For pressure cycles which must be closely controlled during the formation of the workpiece, every limit switch and every pressure regulating valve is used. For less precise operation, only every other limit switch and every other pressure regulating valve is used. Even fewer limit switches and fewer pressure regulating valves can be used if desired.

It is therefore one object of the present invention to provide a hydraulic press having a diaphragm enclosed fluid pressure chamber in which any pressure cycle can be easily set, or changed, as desired. It is another object of the present invention to produce in a press having a diaphragm enclosed fluid pressure chamber, pressure cycles in which any pressure value may, if desired, vary widely from the preceding pressure value. It is still another object of the present invention, to provide, a hydraulic press having a diaphragm enclosed fluid pressure chamber in which the pressure in the fluid pressure chamber is controlled by discrete signals, or commands. Other objects and advantages of the present invention should be readily apparent by reference to the following specification, considered in conjunction with the accompanying drawings forming a part thereof, and it is to be understood that any modifications may be made in the exact structural details there shown and described, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

In the drawings:

FIG. 1 is a side cross-sectional view of a hydraulic press incorporating the present invention;

FIGS. 2, 3, and 4 are views taken on the

lines

22, 33, and 4-4 of FIG. 1;

FIG. 5 is a schematic diagram of the fluid circuitry of the machine of FIG. 1; and

FIGS. 60, 6b, 6c, and 6d are schematic diagrams of electrical circuitry of the machine of FIG. 1.

There is shown in FIG. 1 a hydraulically operated forming press with a frame having four spaced frame members 10 extending upwardly from a recess 11 in foundation 12. A base, indicated generally at 13, is received within the frame members 10. The base has a cylinder 14 which has an annular wall 15, a lower end plate 16, and an upper end plate 17 to define a cylindrical chamber 18. A circular plate 19 is mounted on cylinder 14 and supports a cylindrical bed 20. Bed 20 has a recess therein in which a plunger 21 is received when retracted (as shown in FIG. '1). A workpiece blank 22 can be placed on the bed over the plunger when the plunger is in the position shown in FIG. 1.

A head member 25, which is supported on the frame members 10, has a depending cylindrical portion 26. A sleeve 27 is slidably received over the depending portion 26, and vertical movement is imparted to the sleeve 27 by the two hydraulic motors 28. Each motor 28 comprises a cylinder 29, and a piston 30 slidably received in the cylinder 29. The pistons 30 are connected to the sleeve 27 by connecting rods 31. The lower end of the sleeve 27 is closed by a flexible diaphragm 32 which is secured therein by clamp ring 33. The diaphragm 32, sleeve 27, and depending portion 26 of the head define a chamber 34 which expands when the sleeve is lowered to a closed position on the bed and which contracts when the sleeve is raised to the open position shown in FIG. 1. Fluid from a reservoir 35 passes through passage 36 as chamber 34 expands; and fluid from chamber 34 passes back through passage 36 to reservoir 35 as chamber 34 contracts.

In the operation of the press, a workpiece blank 22 is placed on the bed 20. Solenoid S1 is energized to shift valve plunger 40 of valve 41, against the bias of spring 42, to the extreme right hand position (as shown in FIG. 1). A motor driven pump 43 takes fluid from a sump 44 and delivers it under pressure to pressure line 45. A relief valve 46, connected to line 45 and discharging to the sump, limits the maximum pressure in line 45 to a safe value. Solenoid S2 is energized at the same time as solenoid S1, shifting valve plunger 47 of valve 48 to the extreme left hand position (when viewed as in FIG. 1) and connecting pressure line 45 to motor line 49. Motor line 50 connects at the same time through the valve 48 to return line 51 which exhausts through check valve 52 and line 53 into sump 44. Motor line 49 has two

branches

49a and 49b leading to the upper ends, respectively, of motors 28; motor line 50 has two branches 50a and 50b leading to the lower ends, respectively, of motors 28. With motor line 49 connected to pressure line 45 and motor line 50 connected to return line 51, the sleeve 27 descends, expanding chamber 34. When sleeve 27 reaches the extreme lower limit, diaphragm 32 firmly engages the top of the workpiece blank 22 and chamber 34 is filled with low pressure (atmospheric pressure) fluid from reservoir 35.

Elevation of plunger 21 is effected by energizing solenoid S4 to shift valve member 54 of valve 55 to an extreme left hand position (when viewed as in FIG. 1). With valve member 54 to the left, pressure line 45 is connected, through valve 55, with motor line 56. At the same time, motor line 57 is connected through valve 55 to return line 58 which discharges to the sump through check valve 59 and line 53.

Motor lines

57 and 56 are connected, respectively, to the top and botom of motor 14. With line 56 connected to pressure and line 57 connected to the sump, the piston 60 rises. Piston 60 is received on connecting rod 61, the upper end of which is connected to the plunger 21. As the plunger 21 rises, the pressure in chamber 34 forces the blank 22 around the plunger.

However, before the plunger 21 is raised, it is necessary to increase the pressure in chamber 34 to some predetermined initial value. The initial desired pressure chamber pressure depends on the shape of the workpiece to be formed and may, for example, be 5,000 pounds per square inch. To build u this pressure in chamber 34, solenoid S1 must be deenergized, allowing valve member 40 to shift to the left from the position shown in FIG. 1 to close passage 36. Fluid under pressure is then added to chamber 34 through head member passage 62 which connects to line 63.

The connecting rod 61 extends through bottom plate 16 of cylinder 14 and has a bracket 65 connected thereto. Bracket 65 has two spaced

upstanding rods

66 and 67 connected thereto. Each rod has a collar (68, 69 respectively) secured thereon at the upper end. Each rod extends into a control box 70 connected between frame members 10. As shown best in FIG. 4, the control box has nine limit switches (1L8 through 9L8) on one side which are operated successively by collar 69 on rod 67 as the plunger 21 is raised during forming. When the plunger is retracted (as shown in FIG. 1), the collar 69 is in registration with, and operates, the lowest limit switch (1L8). The control box has two limit switches 10LS and 13LS on the other side which are operated by collar 68 on rod 66, the limit switch 10LS when the plunger 21 is retracted as shown in FIG. 1 and the limit switch 13LS when the plunger 21 is in the extreme upper position.

As shown in FIG. 5, a low volume high pressure fluid pump 71 takes hydraulic fluid from sump '7 2 and delivers it under pressure to pressure line 73. A relief valve 74 is connected to line 73, to limit the maximum pressure therein, and discharges to the sump. A blocking valve 75 has a valve member 76 which shifts to the right from the position shown in FIG. 5 against the bias of spring 77 when solenoid S15 is energized. When solenoid S15 is deenergized, the valve member 76 shifts to the left to the position shown in FIG. 5. When the valve member 76 is to the right, pressure line 73 is connected to a line 78 leading to a valve 79; when the valve member 76 is to the left, pressure line 73 is connected to a return line 80. Valve 79 has a movable valve member 81 which is urged to the left (as viewed in FIG. 5) by spring 82. The valve member 81 has a central spool 83 which divides the interior of the valve into two

chambers

84, 85. Chamber 84, which is in communication with line 78, has an exhaust port 86 connected to return line 80. Chamber has a port 87 connected by line 88 to inlet port 89 of variable relief valve 90. Lines 78 and 88 are connected through a restriction 91. The areas of valve member 81 exposed to the pressure of chamber 84 and to the pressure of chamber 85 are substantially the same and the spring 82 is very light. Thus, if the pressure in chamber 84 exceeds momentarily the pressure in chamber 85, valve member 81 is shifted to the right, allowing fluid to escape through port 86 to the sump until the pressure in chamber 84 equals the pressure in chamber 85. Chamber 84 is connected to line 63 which leads to passage 62 and chamber 34. Thus, the pressure in chamber 84 and hence in chamber 34 follows the pressure in chamber 85 and hence in line 88.

Valve 90 has two spaced

plungers

95, 96 separated by a spring 97. Plunger 96 is connected to a piston 98 received in a recess in the valve. Piston 98 and flexible skirt 99 surrounding the piston divide the recess into two separate air chambers 100 and 101. Chamber 100 has an open passage 102 to the atmosphere and chamber 101 has a port 103 connected to line 104. When the pressure force in line 88 acting on plunger 95 exceeds the force urging plunger 95 to the left (which latter force depends on the air pressure in chamber 101), hydraulic fluid is forced past plunger 95 into passage 105 and return line 106 leading to the sump. Thus, the pressure in chamber 34 is always proportional to the pressure in chamber 101. Since the area of piston 98 in chamber 101 is so much larger than the small area of plunger 95 exposed to line .88, a relatively small air pressure, say 50 pounds per square inch, in chamber 101 will maintain a relatively large pressure, say 5,000 pounds per square inch, in chamber 34. In order to achieve this specific ratio of 100 to l, the area of piston 98 must be 100 times larger than the area of plunger 95 exposed to the pressure in line 88.

For each of the nine limit switches (1L5 through 9LS) there are a pair of pneumatic valves, each pair comprising a blocking valve (1BV through 9BV) and a pressure regulating valve (lRV through 9RV). Each blocking valve has a valve member 110 actuated by one of the nine solenoids (S6 through S14) which are energized, respectively, by operation of the limit switches 118 through 9L5. When the solenoid of a particular valve is energized, the valve member 110 of that valve is shifted to the right, against the bias of spring 111, to connect line 104 with line 112. When the solenoid is deenergized, line 104 is blocked from line 112. When a blocking valve is open (with member 110 to the right) air flows from a source, or tank, 113 of air under pressure through line 114, through the regulating valve connected to the blocking valve which is open, through line 112, through the open blocking valve, and through line 104 to chamber 101.

Each pressure regulating valve has a movable valve member 115 which is urged to the left by spring 116. If air flows through the valve, valve member 115 is urged to the right by the pressure in line 112 (which is the same as the pressure in chamber 101). Movement of valve member 115 to the right throttles the air entering the valve and vents the air in line 112 to the atmosphere so the pressure in line 112 assumes a value depending on the setting of spring 116, which can be adjusted by the set screw 117. Thus, with a particular solenoid (S6 through S14) of a blocking valve energized, the pressure in chamber 34 will depend on the setting of the set screw 117 of the regulating valve connected to that open blocking valve.

With the plunger in the retracted position (as in FIG. 1) and solenoid S6 energized (since limit switch 1LS is operated by collar 68), air flows through the right hand pair of valves 1RV and 1BV) only, since the other solenoids (S7 through S14) are deenergized at this time. Thus, an initial forming pressure of, say, 5,000 pounds per square inch (indicated by gauge G) is in chamber 34. In forming the workpiece blank, different pressure chamber pressures are desirable at different stages of the forming. Suppose, for example, that a part nine inches deep is to be formed and the limit switches 1LS through 9L8 are spaced one inch apart. Suppose also that on each inch of draw, the pressure in chamber 34 *must be raised 1,000 pounds per square inch (starting from a pressure of 5,000 pounds per square inch) for the optimum forming pressure cycle. In this particular case, the right hand regulating valve lRV (which is the only regulating valve effective when limit switch 1LS is operated) is set to produce a pressure of 5,000 pounds per square inch in chamber 34; the next regulating valve 2RV is set to produce a pressure of 6,000 pounds per square inch in chamber 34. Each regulating valve (moving to the left in FIG. 5) is set to produce a pressure 1,000 pounds per square inch higher in chamber 34 than the preceding regulating valve. The extreme left hand regulating valve 9RV is set to produce a pressure of 13,000 pounds per square inch in chamber 34. Thus, as successive limit switches are operated during the forming cycle, successive regulating valves become effective, and the pressure in chamber 34 progressively rises.

In some operations, a pressure change is desired only every two inches of draw (instead of every inch). In this case, every other limit switch is rendered ineffective, and air will flow successively only through every other pressure regulating valve during the forming operation. Similarly, a change may be desired only every fourth inch of draw. Accordingly, only every fourth limit switch is rendered effective, and air successively passes through only every fourth regulating valve.

The circuit diagram for operation of the press is shown in FIGS. 6a, 6b, 6c, and 6d. In the diagram, the contacts of each relay bear the same number as the relay except with a numerical sufiix to distinguish between contacts of the same relay. Two lines L1 and L2 are connected to a source of energy 120 (FIG. 60). Three selector switches 1SW, ZSW, and 3SW (FIG. 6b) are each connected in series with a selector relay (ISLR, 2SLR, and 3SLR respectively) across lines L1 and L2. Switch ISW is closed to energize relay 1SLR if every limit switch (1LS to 9LS) is to be rendered effective; switch ZSW only is closed to energize relay 2SLR if only every other limit switch (1LS, 3LS, 5LS, 7LS, 9LS) is to be rendered effective; switch SSW only is closed to energize relay SSLR if only every fourth limit switch (1L8, SLS, 9L8) is to be rendered effective. Every limit switch is used if a precise, or closely controlled, pressure cycle is desired; every other limit switch is used if a less precise pressure cycle is adequate; and every fourth limit switch is used if an even less exacting pressure cycle is required.

When the sleeve 27 is up, limit switch 11LS (FIG. 1) is operated and the normally open contacts 11LS1 (FIG.

6b) thereof are closed. At the same time, limit switch 12LS (FIG. 1) is unoperated and the normally closed contacts 12LS1 (FIG. 6b) thereof are also closed. When the plunger 21 is retracted, limit switch ltlLS is operated and the normally open contacts 10LS1 thereof are closed. Thus, if push button switch contacts 1PB1 are closed when the sleeve is up and the plunger is down, relay 1CR, which is connected in series across lines L1, L2 with switch contacts 1PB1, 11LS1, 12LS1, and 10LS1, will be energized. Relay lCR is sealed in by the normally open contacts 1CR1 connected across contacts 1PB1 and 11LS1. With relay ICR energized, the normally open contacts 1CR2 close to energize solenoid S1, which is connected in series with contacts 1CR2 across lines L1 and L2. Energization of solenoid S1 opens passage 36 to connect reservoir 35 with chamber 34.

With the sleeve 27 up and limit switch 12LS unoperated, normally closed contacts 12LS2 (FIG. 6a) are closed so that when normally open contacts 1CR3 close on energization of relay 1CR, solenoid S2, which is connected in series across lines L1, L2 with contacts 1CR3 and 12LS2, is energized. Energization of solenoid S2 operates motors 28 to lower sleeve 27. When the sleeve reaches its lower limit with diaphragm 32 resting on workpiece blank 22, limit switch 12LS is operated to open limit switch contacts 12LS1 (deenergizing relay lCR and solenoid S1) and 12LS2 (deenergizingsolenoid S2). On deenergization of solenoid S1, valve member 40 shifts to the left. Thus, during descent of sleeve 27, fluid can flow freely from reservoir 35 to the expanding chamber 34 through passage 36 but after the sleeve reaches the bed, the passage 36 is closed.

When the sleeve 27 reaches bottom and operates limit switch 12LS, normally open contacts 12LS3 (FIG. 6b) close. At this time, normally closed contacts 11LS2 are closed, and solenoid S15 is energized through contacts 12LS3 and 11LS2. Energization of solenoid S15 operates valve 75 to begin the introduction of high pressure fluid through line 78, valve 79, line 63, and passage 62 to chamber 34. At the same time relay 2CR is energized through contacts 12LS3 and 11LS2. Energization of relay ZCR closes the normally open contacts 2CR1 (FIG. 6b) thereof.

Line L3 is connected to line L1 through contacts -12LS3 and 11LS2. A relay 1VR (FIG. 6b) is connected in series with the normally open contacts 1LS1 and with the three normally open, parallel connected, contacts 1SLR1, 2SLR1, and 3SLR1. Thus, if either selector switch 18W, 25W, or 3SW is closed (to energize either relay ISLR, ZSLR, or 3SLR, respectively), relay VR1 will be energized when the plunger 21 is retracted and collar 69 is operating limit switch 1LS. Energization of relay 1VR causes normally open contacts 1VR1 (FIG. 6b) to close, thereby energizing solenoid S6 which is connected in series with contacts 1VR1 across lines L3 and L2. Thus, at this time, the regulating valve 1RV connected to the first blocking valve 1BV determines the pressure in chamber 34, and this regulating valve is set to produce the desired initial charging pressure of, say, 5,000 pounds per square inch. Relay 1VR is sealed in through normally open contacts 1VR2 and a network comprising three pairs of contacts connected in parallel: normally open contacts 1SLR2 and normally closed contacts 2VR1, normally open contacts ZSLRZ and normally closed contacts 3VR1, and normally open contacts 3SLR2 and normally closed contacts 5VR1. Only one of these pairs of contacts is effective to seal in relay 1VR, depending on which of the switches 18W, 28W, 38W is closed. Contacts 2VR1 will open when limit switch 2LS is operated; contacts 3VR1 will open when limit switch 3LS is operated; and contacts 5VR1 will open when limit switch 5LS is operated. Thus, if switch -1SW is closed, relay 1VR will drop out, deenergizing solenoid S6, only when limit switch 2LS is operated to energize solenoid S7. If switch 25W is closed, relay 1VR will drop out, deenergizing solenoid S6, only when limit switch 3L8 is operated to energize solenoid S8. In the latter situation, limit switch ZLS (as well as limit switches 4LS, 6L5, 8L8) is rendered ineffective. If switch 3SW is closed, relay lVR will drop out, deenergizing solenoid S6, only when limit switch SLS is operated to energize solenoid S10. In this latter situation, only every fourth limit switch is effective.

The normally open contacts 2CR1 (FIG. 6b), which are connected in series across lines L3 and L2 with normally open pressure switch contacts 1PS1 and relay 3CR, close when relay ZCR is energized. The pressure switch is set to operate at the desired initial forming pressure and when that pressure (which is the pressure set in regulating valve 1RV) is reached, the contacts 1PS1 close to energize relay 3CR. Relay 3CR is sealed in by normally open contacts 3CR1 connected across the pressure switch. When relay SCR is energized, normally open contacts 3CR2 (FIG. 6a), which are connected in series with solenoid 54 across lines L1 and L2, close to energize that solenoid. This operates valve 55 to begin the elevation of plunger 21.

After the plunger has traveled upwardly one inch, collar 69 operates limit switch 215 to close normally open contacts 2L5 (FIG. 6c). If, and only if, selector switch 1SW is closed (the switch which renders all limit switches effective) will relay 2VR, which is connected in series across lines L3 and L2 with normally open contacts 1SLR3 and ZLSl, be energized. Relay ZVR, if energized, is sealed in with normally open contacts 2VR2 and normally closed contacts SVRZ. It should be noted that, if relay 2VR is energized, normally closed contacts ZVRl open at this time, deenergizing relay lVR. With relay ZVR energized and relay lVR simultaneously deenergized, normally open contacts 2VR3 close and normally open contacts -1VR1 open. This simultaneously energizes solenoid S7 (connected in series with contacts 2VR3 across lines L3 and L2) and deenergizes solenoid S6. Thus blocking valve 2 3V is operated and blocking valve 13V released, connecting regulating valve 2RV into circuit between

lines

114 and 104 and disconnecting regulating valve 1RV. Thus, the setting of regulating valve ZRV will determine the pressure in chamber 34. Regulating valve 2RV may, for example, be set to produce a pres sure in pressure chamber 34 of 6,000 pounds per square inch. It should be noted that if either ZSW or 3SVV instead of 18W is closed, relay 2VR will not be energized, thereby rendering 2LS ineffective. In this latter situation, pressure in chamber 34 will remain at the initial forming pressure (say 5,000 pounds per square inch) until limit switch 3LS is operated (assuming switch 2SW closed) or until limit switch SLS is operated (assuming switch SSW closed).

The next relay 3VR (FIG. 60) is energized if either 1SW or 23W is closed (and either normally open contacts 1SLR4 or normally open contacts ZSLRS are closed) and limit switch 3L8 is operated (to close normally open contacts 3LS1). The relay SVR is sealed in through normally open contacts 3VR3 and either one of two parallel pairs of series connected contacts: normally open contacts -1SLR5 and normally closed contacts 4VR1 (if switch ISW is closed), or normally open contacts 2SLR4 and normally closed contacts VR2 (if switch 28W is closed). Energization of relay 3VR causes normally open contacts 3VR4 to close, energizing solenoid S8. At the same time the previously energized relay and solenoid become deenergized. Thus regulating valve 3RV becomes effective, and the previously effective regulating valve becomes ineffective, to determine the pressure in chamber 34. If switch W is closed, relay SVR becomes deenergized when limit switch 4L8 is operated to energize relay 4VR and open normally closed contacts 4VR1; if switch ZSW is closed, relay 3VR becomes deenergized when limit switch SLS is operated to energize relay SVR and open normally closed contacts 5VR2.

The next relay dVR (FIG. 6c) is energized if, and

only if, switch ISW is closed to energize relay ISLR and close normally open contacts 1SLR6 and when limit switch 4L8 is operated to close normally open contacts 4LS1. The relay is sealed in through normally open contacts 4VR2 and normally closed contacts 5VR3. Energization of relay 4VR causes normally open contacts 4VR3 to close, energizing solenoid S9. At the same time the previously energized relay and solenoid become deenergized. Thus regulating valve 4RV becomes effective, and the previously effective regulating valve becomes ineffective, to determine the pressure in pressure chamber 34. With switch 18W closed, relay 4VR becomes deenergized when limit switch SLS is operated to energize relay SVR and open normally closed contacts 5VR3.

The neXt relay SVR is energized if either switch 15W, switch 25W, or switch 38W is closed (to close either normally open contacts 1SLR7, normally open contacts 2SLR5, or normally open contacts 3SLR3) and limit switch SLS is operated (to close normally open contacts 5LS1). The relay SVR is sealed in through normally open contacts 5VR4 and either one of three parallel pairs of series connected contacts: normally open contacts 1SLR8 and normally closed contacts 6VR1 (if switch 18W is closed), normally open contacts 2SLR6 and normally closed contacts 7VR1 (if switch 2SW is closed), or normally open contacts 3SLR4 and normally closed contacts 9VR1 (if switch 38W is closed). Energization of relay SVR causes normally open contacts SVRS (FIG. 6:2) to close, energizing solenoid S10. At the same time, the previously energized relay and solenoid become deenergized. Thus regulating valve SRV becomes effective, and the previously effective regulating valve becomes ineffective, to determine the pressure in pressure chamber 34. If switch ISW is closed, relay SVR becomes deenergized when limit switch 6L3 is operated to energize relay 6VR and open normally closed contacts 6VR1; if switch ZSW is closed relay 5VR becomes deenergized when limit switch 7L5 is operated to energize relay 7VR and open normally closed contacts 7VR1; if switch 38W is closed relay SVR becomes deenergized when limit switch 9L5 is operated to energize relay 9VR and open normally closed contacts 9VR1.

The next relay 6VR is energized when and only when switch 1SW is closed (to close normally open contacts 1SLR9) and limit switch 6L8 is operated (to close normally open contacts 6LS1). The relay 6VR is sealed in through normally open contacts 6VR2 and normally closed contacts 7VR2. Energization of relay GVR causes normally open contacts 6VR3 to close, energizing solenoid S11. At the same time the previously energized relay and solenoid become deenergized. At this time, then, relay 6VR becomes effective, and the previously effective pressure regulating valve becomes ineffective, to determine the pressure in chamber 34. Relay 6VR becomes deenergized when limit switch 7LS is operated to energize relay 7VR and open normally closed contacts 7VR2.

The next relay 7VR (FIG. 6d) is energized if either 1SW or 25W is closed (to close either normally open contacts 1SLR10 or normally open contacts 2SLR7) and limit switch 7LS is operated (to close normally open contacts 7LS1). The relay 7VR is sealed in through normally open contacts 7VR3 and either one of two parallel pairs of series connected contacts: normally open contacts 1SLR11 and normally closed contacts -8VR1 (if switch 15W is closed), or normally open contacts ZSLRS and normally closed contacts 9VR2 (if switch 28W is closed). Energization of relay 7VR causes normally open contacts 7VR4 to close, energizing solenoid S12. At the same time the previously energized relay and solenoid become deenergized. Thus at this time regulating valve 7RV becomes effective, and the previously effective regulating valve becomes ineffective, to establish the pressure in pressure chamber 34. If switch 1SW is closed, relay 7VR becomes deenergized, when limit switch SLS is operated to energize relay SVR and open normally closed contacts 1 9 8VR1; if switch 25W is closed relay 7VR becomes deenergized when limit switch 9L8 is operated to energize relay 9VR and open normally closed contacts 9VR2.

The next relay SVR is energized if and only if switch ISW is operated (to close normally open contacts 1SLR12) and limit switch 8LS is operated (to close normally open contacts 8LS1). The relay 8VR is sealed in through normally open contacts 8VR2 and normally closed contacts 9VR3. Energization of relay 8VR causes normally open contacts 8VR3 to close, energizing solenoid S13. At the same time, the previously energized relay and solenoid become deenerg'ized. Thus at this time regulating valve 8RV becomes effective, and the previously effective regulating valve becomes ineffective, to establish the pressure in pressure chamber 34. Relay -8VR becomes deenergized when limit switch 9LS is perated to energize relay 9VR and open normally closed contacts 9VR3.

The last pressure controlling relay 9VR is energized if either switch ISW, switch 2SW, or switch 38W is closed (to close either normally open contacts 1SLR13, normally open contacts 2SLR9, or normally open contacts 3LSR5) and limit switch 9LS is operated (to close normally open contacts 9LS1). The relay is sealed in through normally open contacts 9VR4 and normally closed contacts 13LS2 of limit switch 13LS. Energization of relay 9VR causes normally open contacts 9VR5 to close, energizing solenoid S14. At the same time the previously energized relay and solenoid become deenergized. Thus regulating valve 9RV becomes effective, and the previously effective regulating valve becomes ineffective to determine the pressure in pressure chamber 34. Regardless of which of the switches ISW, 2SW or SSW is closed, relay 9VR becomes deenergized when limit switch 13LS is operated by the collar 68 when the plunger reaches the extreme top limit of its stroke.

It will be noted that in the circuit, each valve relay lVR through 9VR is energized through both selector relay contacts and limit switch contacts. The selector switches, if open, leave certain selector relays deenergized. Thus, certain limit switches, the contacts of which are connected in series with the contacts of the denergized selector relays, are ineffective to energize the valve relays, and hence ineffective to render certain regulating valves effective to control pressure in chamber 34.

When the plunger reaches the extreme upper position and limit switch 13LS is operated to close normally open contacts 13LS3 (FIG. 6a), relay 4CR is energized through contacts 13LS3 and normally closed contacts 11LS4. Relay 4CR is sealed in through normally open contacts 4CR1. At the same time, normally open contacts 13LS1 close to energize solenoid S16 and open blocking valve 10BV, venting line 104 to atmosphere and relieving pressure from chamber 34. Energization of relay 4CR causes normally open contacts 4CR2 to close and energize solenoid S3 through contacts 4CR2 and normally closed contacts 11185. This shifts valve member 47 of valve 48 to the position shown in FIG. 1, connecting motor line 50 to pressure line 45 and connecting motor line 49 to return line 51. At the same time, normally closed contacts 4CR3 (FIG. 6b) close to energize solenoid S1, shifting valve member 48 against the bias of spring 42 to open passage 36. Thus, sleeve 27 rises, transferring fluid from chamber 34 to reservoir 35.

When the sleeve 27 reaches the upper limit to operate limit switch 11LS, solenoid S becomes energized through normally open contacts 11LS6. Energization of solenoid S5 shifts valve member 54 of valve 55 to the position shown in FIG. 1, connecting motor line 57 to pressure line 45 and connecting motor line 56 to return line 58. This causes the plunger to retract, permitting removal of the formed workpiece.

What is claimed is:

1. A hydraulic press for forming a workpiece blank, the press comprising in combination:

(a) means including a flexible diaphragm defining a fluid chamber,

(b) means to introduce fluid under pressure into the chamber,

(c) a plunger,

(d) means to draw the plunger and diaphragm together to form a workpiece therebetween, and

(e) means to produce a series of discrete signals for control of the pressure in the pressure chamber during formation of the workpiece.

2. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(a) means defining a fluid chamber, said chamber having a flexible diaphragm to close one end,

(b) a pump in communication with the chamber to introduce pressure fluid therein,

(c) a plunger,

(d) a motor to move the plunger and diaphragm to gether to form a workpiece therebetween, and

(e) a plurality of limit switches operable during forma tion of the workpiece to control the pressure in the pressure chamber.

3. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(a) means defiining a fluid chamber, said chamber having a flexible diaphragm to close one end,

(c) a plunger,

(d) a motor to move the plunger and diaphragm together to form a workpiece therebetween,

(e) a plurality of switches operable when effective to control the pressure in the pressure chamber during formation of the workpiece, and

(f) means selectively to render some of said switches ineffective.

4. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(a) means defining a fluid chamber, said chamber having a flexible diaphragm secured in one end,

(c) a plunger,

(d) a motor to effect relative movement between the plunger and the diaphragm to form a workpiece therebetween, and

(e) a plurality of switches operated successively in response to said relative movement to control the pressure in the pressure chamber.

5. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(c) a plunger,

(d) a motor to effect relative movement between the plunger and the diaphragm to form a workpiece therebetween,

(e) a plurality of switches successively operable when effective to control the pressure in the pressure chamber in response to said relative movement, and

(f) means to render some of said switches ineffective when a less precise pressure cycle is required.

6. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(b) a pump in communication with the chamber to introduce fluid pressure therein,

(c) a plunger,

(d) a motor to effect relative movement between the plunger and the diaphragm to draw the plunger and diaphragm together for forming a workpiece therebetween,

(e) a plurality of pressure regulating valves, each operable when rendering effective to establish a predetermined pressure in the pressure chamber, and

(f) a plurality of limit switches operated successively in response to said relative movement to render said pressure regulating valves effective.

'7. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(c) a plunger,

(e) a plurality of pressure regulating valves, each operable when rendered effective to establish a predetermined pressure in the pressure chamber,

(f) a plurality of switches operable when effective to render said pressure regulating valves eflective in response to said relative movement, and

(g) means selectively to render some of said switches inefliective.

8. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(c) a plunger,

((1) a motor to effect relative movement between the plunger and the diaphragm to draw the plunger and diaphragm together for forming a workpiece therebetween,

(e) a relief valve in communication wth the fluid chamber, said relief valve operable in response to an input pressure to establish a fluid chamber pressure proportional to said input pressure,

(-f) a plurality of pressure regulating valves, each operable when rendered effective to produce an input pressure at said relief valve, and

(g) a plurality of limit switches operated successively in response to said relative movement between the plunger and the diaphragm to render said pressure regulating valves eflfective.

9. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(a) means defining a fluid chamber, said chamber having a flexible diaphragm secured in one end, (b) a pump in communication with the chamber to introduce fluid pressure therein,

(c) a plunger,

(e) a relief valve in communication with the fluid chamber, said relief valve operable in response to an input pressure to establish a fluid chamber pressure proportional to said input pressure,

(f) a plurality of pressure regulating valves, each operable when rendered effective to produce an input pressure at said relief valve,

(g) a plurality of limit switches operable when effective to render said pressure regulating valves successively effective in response to said relative movement between the plunger and the diaphragm, and

(h) means selectively to render some of said limit switches ineffective when a less precise pressure cycle is required.

10. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

til

(c) a plunger,

(d) a motor to move the plunger toward the diaphragm for forming a workpiece between the plunger and the diaphragm,

(e) a relief valve in communication with the fluid chamber, said relief valve operable in response to an input pneumatic pressure to establish a fluid chamber pressure proportional to said input pressure,

(f) a plurality of pneumatic pressure regulating valves, each operable when rendered effective to produce an input pressure, and

(g) a plurality of limit switches operated successively during advance of the plunger to render said pressure regulating valves effective.

11. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(0) a plunger,

(f) a plurality of pneumatic pressure regulating valves, each operable when rendered effective to produce an input pressure,

(g) a plurality of limit switches operable when effective to render said pressure regulating valves successively efiective during advance of the plunger, and

(h) means including a selector switch to render particular limit switches ineffective.

12. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(c) a plunger having an actuating rod connected thereto,

(g) a plurality of limit switches in the path of said actuating rod for successive operation during advance of the plunger to render said pressure regulating valves effective.

13. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(c) a plunger having an actuating rod connected thereto,

((1) a motor to move the plunger toward the diaphragm for forming a workpiece between the plunger and the diaphragm,

(e) a relief valve in communication with the fluid chamber, said relief valve operable in response to 1 3 an input pneumatic pressure to establish a fluid chamber pressure proportional to said input pressure, (f) a plurality of -pneumatic'pressure regulatingvalves,

each operable-when rendered effective to produce an I input pressure, g

(g) a plurality o f limit'switches in the path of said actuating rod for successive operation during advance of the plunger, each limit switch operable when effective to render a pressure regulating valve efiective, and

(h) at least one selector switch to render particular limit switches ineffective.

14. A hydraulic press for forming a workpiece blank comprising in combination:

(a) a frame,

(b) a bed,

(c) a head at the upper end of the frame having a fluid reservoir therein and having a depending portion,

((1) a sleeve received on the depending portion of the head having a flexible diaphragm secured in the lower end thereof, said sleeve operable to lower the diaphragm to the bed for closing the press and operable to raise the diaphragm to the depending portion of the head for opening the press, said sleeve, diaphragm, and depending head portion defining a fluid chamber which expands and draws low pressure fluid from the reservoir when the press closes and which contracts and returns fluid to the reservoir when the press opens,

(e) a pump in communication with the chamber to introduce high pressure fluid therein,

(f) a plunger received in the bed and having an actuating rod connected thereto,

(g) a motor to move the plunger toward the diaphragm for forming a workpiece between the plunger and the diaphragm and to advance the actuating rod,

(h) a relief valve in communication with the fluid chamber, said relief valve operable in response to an input pneumatic pressure to establish a fluid chamber pressure proportional to said input pressure,

(i) a plurality of pneumatic pressure regulating valves, each operable when rendered effective to produce an input pressure, and

(j) a plurality of limit switches in the path of the actuating rod for successive operation during advance of the actuating rod to render said pressure regulating valves eflective.

15. A hydraulic press for forming a workpiece blank comprising in combination:

(a) a frame,

(b) a bed,

() a head at the upper end of the frame having a fluid reservoir therein and having a depending portion,

((1) a sleeve received on the depending portion of the head having a flexible diaphragm secured in the lower end thereof, said sleeve operable to lower the diaphragm to the bed for closing the press and operable to raise the diaphragm to the depending portion of the head for opening the press, said sleeve, diaphragm, and depending head portion defining va fluid chamber which expands and draws low pressure fluid from the reservoir when the press closes and which contracts and returns fluid to the reservoir when the press opens,

(i) a plurality of pneumatic pressure regulating valves, each operable when rendered effective. to produce an input pressure,

(j) a plurality of limit switches in the path of the actuating rod for successive operation during advance of the actuating rod, each limit switch operable when effective to render a pressure regulating valve effective, and

(k) a selector switch to render particular limit switches ineffective.

16. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(0) a plunger,

(e) a relief valve in communication with the fluid chamber, said relief valve operable in response to an input pressure to establish a fluid chamber pressure proportional to said input pressure, and

(f) a plurality of pressure regulating valves operable during formation of the workpiece to produce an input pressure at said relief valve.

17. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(c) a plunger,

(f) a plurality of pressure regulating valves operable when effective during formation of the workpiece to produce an input pressure at said relief valve, and

(g) means selectively to render some of said pressure regulating valves ineffective.

18. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(a) means defining a fluid chamber, said chamber having a flexible diaphragm secured in one end, (b) a pump in communication with the chamber to introduce pressure fluid therein,

(c) aplunger,

(f) a plurality of pressure regulating valves operated successively during formation of the workpiece to produce an input pressure at said relief valve.

19. A hydraulic press for forming a workpiece blank,

the press comprising in combination:

(c) a plunger,

(e) a relief valve in communication with the fluid chamber, said relief valve operable in response to 15 an input pressure to establish a fluid chamber pressure proportional to saidinput pressure,

(f) a plurality of pneumatic pressure regulating valves successively operable when effective during formation of the workpiece to produce an input pressure at said relief valve, and I p (g) meansselectively to render some of said pressure regulating valves ineffective.

'1 6 References Cited 2,766,711 10/1956 --Dever et al.' 7263 3,046,923 7/ 1962 Yolin v'7228 3,125,053 3/1964 Mitchell 729-63 RICHARD J. HERBST, Primary Eicam'inr.

Claims

1. A HYDRAULIC PRESS FOR FORMING A WORKPIECE BLANK, THE PRESS COMPRISING IN COMBINATION: (A) MEANS INCLUDING A FLEXIBLE DIAPHRAGM DEFINING A FLUID CHAMBER, (B) MEANS TO INTRODUCE FLUID UNDER PRESSURE INTO THE CHAMBER, (C) A PLUNGER, (D) MEANS TO DRAW THE PLUNGER AND DIAPHRAGM TOGETHER TO FORM A WORKPIECE THEREBETWEEN, AND (E) MEANS TO PRODUCE A SERIES OF DISCRETE SIGNALS FOR CONTROL OF THE PRESSURE IN THE PRESSURE CHAMBER DURING FORMATION OF THE WORKPIECE.