US2251274A - Pump control - Google Patents

Description

Aug, 5, 1941. A' w. ERNST 2,251,274

PUMP CONTROL Original AFiled Aug. 5, 1935 1o sheets-sheet 1 Aug. 5, 1941. w. ERNST y 2,251,274

PUMP CONTROL Original Filed Aug. 5. 1935 1Q Sheets-Sheet 2 W. ERNST PUMP CONTROL Aug. 5, 1941.

Original Filed Aug.

1o sneets-sheet 4 W. ERNST PUMP CONTROL Original Filed Aug. 5', 1935 Aug. 5, 1941.

Aug. 5, 1941.

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W. ERNST PUMP CONTROL Original Filed Aug. 5, 1935 lO Sheets-Sheet 5 Aug. 5, 1941. lw. ERNST 2,251,274

` PUMP CONTROL Original Filed Aug. 5, 1935 10 Sheets-Sheet 6 Aug. 5, 1941. w. ERNST 2,251,274

PUMP CONTROL' Original Filed Aug.- 5, 1935 10 Sheets-Sheet 8 ug. 5, '1941. W- ERNST l2,251,274

PUMP CONTROL A Original Filed Aug. 5. 1955 f l0 Sheets-Sheet 9 Fl' I4.

W. ERNST PUMP CONTROL Aug. 5, 1941.

Original Filed Aug. 5, 1935 l0 Sheets-Sheet lO WIM 75l? EIMS 7'.

l Patented'Aug. 5, 1941 PUMP CONTROL Walter Ernst, Mount Gilead, Ohio, asignor to The Hydraulic Press Corp., Inc., Wilmington, Del., a corporation of Delaware Original application August 5, 1935, Serial No.

34,652, now Patent No. 2,190,939, dated February 20, 1940. Divided and this application July 30, 1936, Serial No. 93,465

12 Claims.

This invention relates to hydraulic machinery, and in particular, to circuits and devices for controlling presses and similar hydraulic machinery.

One object of this invention is to provide an electro-hydraulic circuit for electrically regulating the condition of the hydraulic circuit wherein the electrical circuit is controlled by means associated with the pump control mechanism.

Another object is to provide an electrical circuit arranged to energize an electrical device, which in turn,1 shifts a valve to vary its positions so as to control the .operation of a hydraulic circuit containing a hydraulic machine and a pump with a pump control system having an electrical circuit regulator associated with the pump control so that the latter operates the former when the attainment of a predetermined pressure in the hydraulic press circuitl causes the pump control to shift.

Another object is to provide such an electrohydraulic circuit wherein the said valve is a four-way valve having a by-pass arrangement for automatically by-passing the delivery of the pump until the pressure has been suiliciently released from the main cylinder, whereupon the press delivery is automatically applied tothe pull-back cylinders to accomplish the return stroke of the press.

This is a division of my copending application, Ser. No. 34,652, filed August 5, 1935, since issued as Pat. No. 2,190,939.

lin the drawings:

Figure 1 is a diagrammatic view, partly in section, of the hydraulic circuit of this invention, with the principal elements thereof shown in diagrammatic form.

Figure 2 is a side elevation of the press and associated control mechanism according to the present invention.

Figure '3 is a front elevation of the press shown in Figure 2.

Figure 4 is a central, vertical section through the press, taken along the line 4--4 of Figure 2.

Figure 5 is a central, vertical section through a pump, showing the electrical circuit regulating device associated with the pump control.

Figure 6 is an enlarged detail view of the electrical circuit regulating device shown in Figure 5, with the parts in a position disengaged from the switch.

Figure 7 is a view similar toFigure 6, but with the parts in a position engaging the switch.

Figure 8 lis a view, partly in section, taken 4 along the line 8-8 of Figure 6.

with the valve in its second position, i. e. during 10 the pressing operation.

Figure 12 is a view similar to Figure 10, but with the valve in its third position, i. e. during the interval between the forward and return' strokes of the press, and While the pump dis- 1 5 charge is being by-passed during the release of pressure from the main cylinder. Y v

Figure 13 is a view similar to Figure 10, but

with the valve in its fourth position, i. e. during the return stroke of the press.

Figure 14 is a view similar to Figure 10, but

with the valve in its fifth position, i. e. While the press is idle at the top of its return stroke.

Figure 15 is an end elevation of the valve shown in Figures 10 to 14.

25, Figure 16 is a vertical section along the line Figure 17 is a vertical section along the `line lk'l--l'l of Figure 10. 1

Figure 18 is a vertical section along-j the line Iii-lil of Figure 13. e

Figure 19 is a top plan view of the valve shown in Figures 10 to 18.

Figure 20 is a front elevation of the valve shown in Figure 19.

- Figure 21 is a bottom plan view of the valve shown in Figure 19.

General arrangement In general, the present invention is concerned with a control system for operating a press, in

which a pump is employed in connection with a multi-position valve, the valve itself being so shifted to apply the pressure fluid from the pump selectively to the main cylinder for a pressing stroke, to the pull-back cylinders for a re turn stroke, to by-pass the pump discharge while releasing the pressure from the main cylinder between the forward and return strokes, and to by-pass the pump discharge and cause the press to be held at the top of its return stroke.

Hitherto, when four-way valves have been employed with a pump discharging in one direction, it has been found diicult to control the release of the pressure from the large main cylinder during the operation of the valve. If the valve was opened quickly a recoil resulted, due to the sudden release of pressure from the main cylinder. On the other hand, if it was attempted to release the pressure slowly or release it through a restricted opening, then a time interval occurred during which there was no place for the discharge of the pump to go. The pump discharge was to be directed into the pull-back cylinders, but could not return the press until after the pressure had dropped from the main cylinder. If this pressure drop occupied too long a time, a shock was set up in the pump and discharged into the pull-back cylinders without causing the platen to move.

The present invention includes a valve having an additional valve stem which is automatically held open by the pressure in the main cylinder as long as there is any pressure in this main cylinder, this additional valve stem providing a by-pass for the pump until all pressure has been released from the main cylinder. In this manner there is provided a controlled release of pressure from the main cylinder at any desired speed, and yet the pump discharge is automatically by-passed while the release of pressure in the main cylinder takes place. After this main cylinder pressure is fully released, the by-pass automatically closes and permits the pump discharge to now into the pull-back cylinders and return the press. In this way there is provided a smooth release of pressure, and a smooth pickup on the pull-back stroke.

The valve in the present invention is actuated by electrical means controlled by a switch associated with the pump control mechanism, thereby eliminating the necessity for separate pressure switches, or similar devices. The electrical circuit containing these devices is arranged so that the press may be operated in three diierent ways: Completely automatic operation, wherein the press automatically performs an indeterminate number of pressing and return strokes without halting at the end of the return stroke; semi-automatic operation, wherein the press is caused to execute a pressing and return stroke, and then halt at the end of the return stroke; and manual operation, wherein the operation of the press is controlled manually so that the operator controls the point at which the press platen will stop at the end of the pressing stroke and/or the return stroke.

Figure 1 shows a diagrammatic layout of/the principal elements involved in the system of this invention. In Figure 1 is shown a press, generally designated l, connected to a `control valve, generally designated 2, which receives vthe discharge of a pump, generally designated 3. The pump 3 is provided with a pressure-responsive control device, generally designated 4, which returns the flow-control element of the pump to a neutral position upon the attainment of a. predetermined pressure, the amount of which may be regulated by the adjusting mechanism, generally designated 5. An electrical circuit-breaking device, generally designated 6, is associated with the pressure-responsive device 4 and actuated thereby to control the energization of the electrical devices employed for shifting the control-valve 2 to its various positions. As hereinafter explained, the control valve 2 may also be shifted mechanically by devices associated with the press. The pump 3 is driven by the electric motor 1 (Figure 3).

Press construction and associated mechanism The press I, shown in the drawings, has vincorporated therein the various devices of-this invention, and consists of a base I0 and a top member II interconnected by strain rods I2, and clamped thereto by the nuts I3. The base I0 has associated therewith a work table I4.

The main cylinder 26 contains a main plunger 21, passing through a packing 28 compressed by a gland 29 through the cap screws 30, thereby preventing leakage from the main cylinder 26 around the main plunger 21t To the lower end of the main plunger 21 is attached the platen 3 I, which is reciprocably mounted upon the strain rods I2, and which is held i'n engagement therewith by the end plates 32 secured to the platen by the cap screws 33.

The platen 3l in its central plane and at its outer extremities contains projecting portions forming arms 34, which have bores 35 arranged to receive the ends of pull-back piston rods 3 6 (Figure 4), these being secured thereto by the nuts 31 threaded on the lower ends thereof. The piston rods 36 have pull-back pistons 38 mounted on the upper endsthereof, and arranged to reciprocate within the pull-back cylinders 39 mounted on either side of the main cylinder 26. The ports 40 beneath the pull-back pistons 38 open into the pipe line 4I, which serves to convey fluid thereto from the control valve 2, in a manner described below. Similarly, the upper ends of the pull-back cylinders 39 contain ports 42, from which pipe lines 43 run to the ports 44 of the surge tank 45 to drain off leakage from the pistons. Escape of uid from the pull-back cylinders 39 is prevented by the packings 46 compressed by the glands 41 around the piston rods 36.

The head of the main cylinder 26 (Figure 4) is provided with a bore 48, arranged to receive a surge valve 49, to which is attached the actuating pipe 5I) running therefrom to a connection with the pull-back cylinder pipe line 4I (Figure 1). The surge valve 49 serves to permit the prefilling of the main cylinder 26, while the main plunger 21 is moving downward under gravity at the beginning of the forward stroke; and also serves to release uid from the'main cylinder 26 during the return stroke of the platen. 'I'he fluid for this purpose is taken in from and returned to the surge tank 45. The details of the surge valve 49 form no part of the present invention, and a complete disclosure thereof will be found in United States patent to Ernst, No. 1,892,568, issued December 2'1, 1932.

Movably mounted in lugs 5I and 52 in the upper and lower press members I I and I0, respectively, is a press control rod 53 (Figures 2 and 3). An arm 54 extends outwardly from the platen 3| and encircles the control rod 53 in such a manner as to engage an adjustable stop 55 thereon to lift the control rod 53 upon its upward or return stroke. The control rod may also be shifted by means of a hand lever 56 of bellcrank form, and pivoted, as at 51, upon the frame boss 58. The outer end of the bellcrank portion of the hand lever 56 is yoke shaped, and provided with a pair of rounded portions 59, making contact-with collars 60 mounted upon the control rod 53 (Figure 2).

Also mounted on the control rod 53 on the upper portion thereof is an adjustable collar 6I, arranged to engage the lever of a limit switch 62, the instant of actuation being varied by moving the collar l up or down the control rod 53. Still further up the control rod 53 is a collar 63 (Figure 2), arranged to engage the rounded ends 64 on the yoke-shaped end of a lever 55, which is pivotally mounted on the shaft 66. The latter is mounted upon the upper member of the press. Pivotally connected to the opposite end of the lever |55 from the ends 04 is a clevis 61, having secured thereto a link 68 leading to a clevis 69 pivotally mounted upon the armature 10 of a solenoid 1|. Adjacent the solenoid 1| and controlling the solenoid is a magnetic switch 12, the operation of which is described below.

operatively connected to the lever 65 and mounted to move upon the same shaft 6E, is an arm 13. On the outer end of the arm 13 is pivotally mounted a clevis 14, to which is attached a connecting rod 15 leading to a clevis 16, pivotally mounted upon the end of a lever 11. The latter is pivotally supported on the shaft 18, near its mid point, and on its lower end is provided with a clevis 19 pivotally mounted..

thereon and connected to the operating rod B8 of the control valve 2. The details ci the control valve 2 are described below. Consequently, it will be seen that when the solenoid 1| is ener-V gized the armature 10 will be drawn downward, the operating rod 80 moved to the left. When the solenoid `'ll is deenergized, however, the spring 91 will force this linkage in the opposite direction, moving the solenoid armature 10 upward, and the valve operating. rod 80 to the right.

Leading to'a single connection 34 on the upper side of the control valve 2 is the pressure line 8|, whose other yend terminates at the pressure coupling 82 of the pump 3. The suction coupling 83 thereof is joined to the surge tank 45 by the pipe line 83, giving access thereto through the port 85 (Figures 1 and 2). Leading from theconnection 95 on the lower side of the control valve 2, to the pull-back line 3|, is the pipe line 88. The pipe line 81 similarly leads from another bottom connection 96 of the control valve 2 to the port 88 in the main cylinder 26 (Figures l, 2 and 4. A connection 89 (Figure 4) serves to support the control valve 2 upon the upper member ofthe press, and also to provide an exhaust duct leading through the pipe line 38 to the surge tank l5 by way of the port 3| therein. Valves 32 and 93 control the discharge of uid Vfrom the lines 98 and 83, respectively, into the surge tank 35 (Figure 2). Mounted on the rear side of the upper press member is the pump 3, driven by the motor 1| (Figure 3).

Pump control mechanism The pump 3 is of the variable delivery type, and consists of a casing (Figure 5),having bearing pads |0| arranged to reciproca-bly support a shift ring |02, wh? .1 rotatably supports a secondary rotor |03. Gn the secondary rotor are guide blocks |83, arranged to reciprocably receive the crossheads of pistons |05. The pistons |05 reciprocate in cylinder bores |06 within a primary rotor or cylinder barrel |01. The latter is rotatably mounted upon a hollow pintle |08,

provided with valve passages serving to transmit fluid to and' from the cylinder bores |06, in a manner well known to those skilled in the art. Consequently, when the shift ring |02 is moved, the secondary rotor |03 will be caused to rotate around an axis which is eccentric to the axis of the primary rotor |01 upon the pintle |08. This eccentricity will caus'e the piston |05 to reciprocate radially in the cylinder barrel or primary rotor |01, while their crossheads reciprocate tangentially in theguide blocks |04.

Secured to one side of the shift ring |02 by the threaded connection |09 is a rod H0, having a screw threaded portion at its outer end. Threaded upon this portion ||I is the hub ||2 of a hand wheel ||3, which engages a slidable sleeve ||4 through the intermediate agency o a ball thrust bearing H5. Surrounding the rod H0, with one end engaging the inner end of the sleeve H4, is a coil spring ||6, the opposite end ofv which engages' a collar ||1, surrounding the rodl l0 and abutting the casing |00of the pump. A nut I|8 on the threaded outer end ||9 of the rod ||0 prevents dislodgment of the hand wheel H3. The sleeve' ||4 is reciprocable within the casing |20 of the adjusting device 5, this casing being secured to the pump casing |00 by the bolts |2 I. The rod ||0 passes through a bore '|22 in the casing |00. Consequently, by rotating the hand wheel ||3 the spring ||6 may be compressed to impart any desired amount of force to the rod ||0.

Secured to the opposite side of the shift ring |02, as by the threaded connection |23, is a rod |24 which passes through the bore |25 in the pump casing |00, and also through the bore |26 in the casing |21 of the pump control device 4. Within the casing |21 is a chamber |23, and within this chamber the rod |24 is enlarged to provide an annular piston head |29. The port |30 provides access to the chamber` |28 and is joined to the pipe |3| leading to the pressure coupling 32 of the pump 3 (Figures 1 and 5). The casing |21 is secured to the pump casing |03 by means of the bolts |32.

The enlarged portion of the rod |24 is arranged to reciprocate within an enlarged bore |33, coaxial with the bore |25 on the opposite side of the chamber |28 (Figure 6). The end of the enlarged portion of the rod |20 terminates in-a counterbore |34, which continues from a bore |35 passing entirely through the rod |23 from the interior of the pump casing |03 at its threaded connection |23. Diagonal passageways |36 lead from the outer end of the rod |24 into the bore |35 so as to provide free passage of oil therethrough. Mounted in the counterbore is a hollow plug |31 containing a bore |38, arranged to receive a coil spring |33. One end of the coil spring engages the plug |30, threaded into the upper end of the bore |38 (Figure 6), whereas the opposite end engages the enlarged portion |3| of a switch operating rod |42 which passes through a bore |43 in the end of the hollow plug |32. The outer end of the hollow plug |31 passes through a bore |43 in the end wall of a switch casing |45, the latter being secured to the control casing |21 by the bolts |48 (Figure 8).

Surrounding the hollow plug |31 is an arinular oil seal |41, held in position by an annular plate |38, secured by the ,screws |49 to an annular projection |50 upon the end wall of the switch casing |45. The threaded aperture |5| in the end of the control casing |21 is provided for purposes not connected with the present invention. The switch casing |45 contains a cover plate |52, heldin engagement. therewith by the bolts |53. The cover plate |52 gives access to a normally closed single-throw switch |54 secu'red to the switch casing |45 by the bolts |55. The contact button |56 of the switch |54 is arranged in line with the switch operating rod |42 on the end of the plug |31 in the rod |24 (Figures 6 and 8). Ports |51 provide drainage of any oil which may escape past theeo'il seal |41.

When it is desired to cause the pump to deliver fluid the hand wheel ||3 is turned so as to move the shift ring |02 to a position which is eccentric of the pintle |08 and primary rotor |111, compressing the spring I6. As the pumpperates it builds up pressure, this pressure being'fcommunicated through the line |3| from `Vthe pressure coupling 82 to the chamber |28. This pressure acts against the annular piston head |29, and when it increases to a suiciently large amount it overcomes the resistance of the coil spring ||6 and moves the pump shift ring |02 downward toward its neutral position (Figure 5). In this manner the pump is caused to regulate itself and to cut down its own discharge when its delivery approaches a predetermined pressure. When the I shifting of the shift ring 02 thus takes place,

through the action of the annular piston head |29; the same action causes the switch operating rod |42 to move from its disengaged position (Figure 6) to its engaged position (Figure 7), operating the switch |54 and opening its normally closed contacts. This brings about a control of the solenoid 1| through the magnetic switch 12, in the manner described below.

Control 'valve construction and operation 'Ihe control valve 2 consists of a casing |68 (Figures 10 to 21), provided witha pair of substantially parallel bores |6| and |62 (Figure 10). The opposite ends of the bore |6| are closed by the annularv plugs |63, having the packings |64 for preventing the escape o'f iiuid. The screws |58 serve to secure the plugs 63 to the casing 60 (Figure 15). Passing through the apertures |65 in the annular plugs |63 is a valve rod |66, having threaded ends |61. Mounted onone of these threaded ends |61 is a clevis |58, which pivotally engages, as at |69, a clevis |10 mounted on the end of the valve operating rod 80 (Figures 2 and 10).

The valve rod |66 is provided with a plurality of heads |1|, |12, |13 and |14. The heads |1| and |14 serve to limit the reciprocation of the valve rod |66 by engaging the annular plugs |63 at the opposite limit of reciprocatio'n. The valve head |12 is provided with oppositely drilled passages |15 and |16, which serve for the passage of fluid in the mid-position of the valve shown in Figure 14, at which time the valve is in the position for causing the platen to remain idle at the top of its stroke.

'I'he valve bore |6| is provided with a plurality of enlarged ducts |11, |18, |19, |80 and |8|. The duct |11 leads from the bore |6| to the choke bore |82.. the latter receiving the choke screw |83, threaded therein and arranged to partially close the aperture |84 in the end thereof. The end cap |85 covers the end of the choke screw |83 and prevents it from being accidentally rotated. 'Ihe aperture |84 opens into the exhaust duct |86, passing through the connection 89 by which the valve is supported upon thev press head The duct |8| also establishes communication between the valve Ibore |6I and the choke bore |81. The latter is of similar construction to the choke bore |82. and receives -a choke screw |88, threaded therein and having a tapered end, partially closing the aperture |89, likewise leading into the exhaust duct |86. The choke screw |88 is similarly covered by an end cap |90 for a similar purpose to the end cap |85. The choke screws |83 and |88 are provided with drilled passages 9| and |92, respectively, these providing drainage into the exhaust duct |86 from the annular chambers |93 and |94 surrounding the choke screws |83 and |88, and communicating by the drilled passages |95 and |96 with the opposite ends of the valve bore |6l. The outer end of the duct |8| communicates with the valve bore |62. The ducts |18 and |80 also establish intercommunication -between the valve bores |6| and |62. 'I'he outer end of the valve bore |62 is closed by a threaded plug |91, giving access to the interior thereof.

Reciprocably mounted in the valve bore |62 is a valve rod |98, having spaced heads |99 and 200 thereon. An enlargement 20| in the chamber 202 serves to limit the motion of the valve rod |98, and is urged to the left by the coil spring 203, whose opposite end rests against the inner wall of 'the spring cap 204. The latter is secured to the casing |60 by means of the screws 205. Fluid is permitted to enter the duct |19 in the valve bore |6| through the port 206. The latter communicates with the upper connection 94, leading to the pressure pipe line 8| from the pump 3. The port 201 leads from the duct |18 to the lower left-hand connection 96, whence the pipe line 81 leads to the main cylinder 26. A third port 208 leads from the duct |80, within the valve bore I 62, to the outer connection 95, from which the pipe line 86 runs to the pipe line 4| of the pull-back cylinders`39 (Figures 1 and 10).

In the operation of the control valve 2 the valve rods |66 and |98 may occupy any one of the live different positions shown in Figures 10 to 14, inclusive. They first position of the control valve 2 provides for the forward movement of the press, and is shown in Figure 1|).v In this position the fluid from the pressure coupling 82A of the pump 3 passes falong the pressure line 8|, through the connection 94 and port 206, into the duct |19, thence through the passageway provided between the valve heads |13 and |12, into the duct |18, thence through the port 201 and the connection 96, to and 4through the line 81 leading to the main cylinder 26 (Figures 1 and 10).

At the same time the oil from the pull-back cylinders 39 proceeds through the pipe lines 4| and 86 to the connection 95, thence through the port 208 into the duct |80, thence through the passageway between the valve heads |13 and |14 into the duct |81, thence through the choked aperture |89, into the exhaust duct |86, thence through the pipe line into the surge tank 45, through the port 9| thereof (Figures 1 and 10). The choke screw |88 permits the rapid traverse speed of the platen to be adjusted by varying the size of the annular passage through the aperture |89 into the exhaust duct |86.

As soon vas the press platen encounters the resistance of the work-piece, Athe pressure built up in the system will force the lower valve head |99 to the right into the position shown in Figure 11. This position is maintained during the pressing operation, and the fluid coming from the pull-back cylinders 39, through the port 208, is additionally permitted to pass outward through the duct 18|, as well as through the duct |80.

When the desired pressure has been exerted upon the work-piece, the valve rod |66 is moved tothe right into the position shown in Figure i3, either manually, by means o! the hand lever' 88 or by the solenoid 1|, as energized by the opening oi the normally closed switch |88 assoelated with the pump 8. In this position the pump discharge proceeds through the port 288 and into the duct |18, and thence through the annular lpassageway between the heads |12 and |18 into the duct |88. thence through the annular passageway between the heads |88 and 288 on the valve rod |88. into the duct |81. and thence outward' through the choked aperture |28 into the exhaust duct |88, returning to the surge tank 88 by the line 88.

' In this manner the discharge oi the pump is diverted to the surge tank 88; and thus bypassed while the pressure is discharging from the main cylinder 26. The iluid trom the main cylinder 28 proceeds through.the port 88and aac 1,1miv

' ward through the choked passageway |88 into the valve head |12, into the duct |11. thence outthe, discharge duct |88. and back to the surge tank 88 by way ot the pipe line 88.

The huid in the pull-back cylinders 88 is imprisoned in this position by the alve head |18 covering the entrance to the uct |88. The platen accordingly halts and remains in a ilxed position while the control valve 2 la in its nith position (Figure 14) Should there be any tendency ior'the platen to coast downward the valve rod |88 will shift to the right, thus opening'up a connection between the port 288 .trom the pump 8 and the duct'` |88 leading to the port 288s so the line 21. through the connecticn 88 and the port 281 into the duct |18, and thence through Ithe annular passageway between the i ,release 6r the pressure fluid in the main cylinder heads|12 and |1| into the duct |11, thence outward past the choked aperture-|84 into the exhaust duct |88. and thence to the surge tank 88 by way ot the line 88.

Thus the choke screw |88 may be adjusted so that a gradual and slow release ci the pressure iluid from the main cylinder can take place,

without any shock because thepump discharge is by-,passed while this release is taking place.

This provision gives n place for' the ilow oi the l`pump to be diverted while the gradual release of the pressure in the main cylinder takes that pressure iiuid ilows along the line 88 and the pull-.back cylinders, returning the platen to v its `previous position. By the same action the by-pass connection through the drilled passages |18 and |18 in the valve head |12 is closed. -Conseouently, the press platen is automatically re-. turned to its top position whenever any tendency to trip downward is started;

Electrical andhydraulic operation The detailed operation ci the control valve 2' has been described'immediately above. This controivalve is operated by the 4 valve-operating rod place, for otherwise pressure from theipump could not lift the platen 8| by means of the pull` back pistons 88 so long as there was pressure in the main :cylinder 28. The piston valve a.r rangement on the valve rod |88, therefore, permits the/pump to bypas s freely while the slow takes placa-thereby avoiding the shock and water hammer occasioned by' sudden releases oi pressure. a

As soon as the pressure-in-the main cylinder i has been released, as determined by the adjustment of the choke screw' |88, the spring 288 shifts' the valve rod |88 and ,igt's valve heads |88 and 288 tothe fourth position of the valve. as shown in Figure 18, thus shutting olf the bypassing arrangement oi the'p'ump. The pump now. discharges from the -porti2288 oi the .valve 2v into the duct |18. throughifthe annular passageway between the valveh'e'ads |12 and |18. and through the duct |88,' in to the port 288. thence through the conneotiongfii and pipe linesv4 88 and 8| to the pull-back cylinders 88. The pump new discharges into the pull-back cylinthis position the fluid from the pump entering the control valve 2 through the port 288 passes through the annular passageway to the right oi the valve .head L12, thence through the drilled passageways in the valve head |12, thence. into the duct |18, thence through' the drilledf. passageways |16 in 'the valve head |12, and( the arm 18 and the lever 88 (Figure 2).

88 through the lever 11, the connecting rod 18. The latter may be operated either by the action oi the hand level` 88 upon the control rod 88, or by the energlaation of the lsolenoid 1|. according to .the manner described below, or by spring 81. t

The solenoid 1| and its electrical lconnections are shown in Figure 9. Power current is received from thelines 2|8 and 2|I and passes to the magnetic switch 12. I! the latter is closed the current from the lines 2|8 and 2| passes through the switch blades 2|2 and 2|8 into the lines 2|5 and 2|8. running to the solenoid 1|. A third switch blade 2H oi the magnetic switch 12 serves toclose and open a holdingwircuit for the operating coil oi 'the magnetic switch 12. Also included inthe circuit shown in Figure 9 is the normally open forward switch 2|1, the normally closed reverse switch 2 I8 and theselector switches -2|il and 228. These switches are mounted upon the switch box 22|. which in turn,. is mounted ders 88 and starts the return stroke oi the press.

upon the arm 222 (Figure 2) secured-to the base member i8 of the press.Y

Qontrol current to actuate of the magnetic switch 12 -is received irom the lines 228 and 228 connected to the power lines 2li and 2|8, respectively. theline- 228 -being connected to the resistor 225.-'.Ong-the `other side o! the resistor 228 the line 228 'runsto one side' oi' the selector switch 2|8, from the opposite side o! which the line 221 runs toene side ci 'the operating coil ci the magnetic 'switch v12. From the opposite side oi the latter v the-line 228 runs to one side o! the forward switch2|1. A branch line 228 runs from the line-1228 to one' o! the" iblade contacts engaged by'thezswltch blade 2H;

From the opposite contact'thereoi the line 288 through the annular'passageway to thefleit oi75 runs to one side oi the switch |88.- actuated by the pump control mechanism.

From the opposite side o! this switch the line 28| runs to one side oi the'reverse switch 2|8, the opposite side ci which is -connected to the line 22|, previously described.l From the line 228 the branch -line 282 'runs to one side of the limit switch 82, the opposite sides-ot which is connected to the selector switch 228 by the line 288. From, theV remaining terminal oi the selector switch 228 the line 28| runs to the remainthe operating coil.

A operating coll thereof through the branch line 229, the switch blade ing terminal of the forward switch 2|1, whence the line 235 runs to a connection with the line The electrical circuit enables the press to be controlled in three diilerent ways. U/nder completely automatic control the platen performs an indeterminate number of -working and return strokes without' halting at the end of each return stroke. In semi-automatic operation the platen performs a working stroke and a return stroke, halting at the end of the return stroke. Under manual operation the press is controlled by the operator as to the termination of either or both of its4 strokes. f' l For completely automatic operation the operator closes the selector switches 2|9 and 220. He then depresses the forward switch 2 1. These actions energize the operating coi] of the magnetic switch 12 by current passingfrom the line 2li, through the line 223, the resistor 225, the line 225, the selector switch 2|9, the line 221, the operating coil of the magnetic switch 12, the line 228, the forward switch 2I1, the line 235, the line 238, the pump-operated switch |54, the line 23|, the reverse switch 2|8 and the line 224 leading to the zpower line 2|0. 'I'he energization of the magnetic switch 12 causes its switch blades 2|2 and 2|3 as well as 2|4 to close, whereupon the remains energized 2|4 and the line 23|, even when the operator releases the forward switch 2|1 to break the circuit between the lines 228 and 235.

As the magnetic switch 12 closes the solenoid 1| becomes energized by as lines zlsrand zls becoming connected to the' power lines 2li) and 2|| through the switch blades 2 I2 and 2|3. When thisoccurs the solenoid 1| (Figure 2) isdrawn downward, moving the arm 13 to the right and the valve rod |68 to the left, into the vposition shown in Figure 10. The press -platen then starts downward and performs its pressing operation, with the control valve 2 taking its second position as previously described in connection with Figure 11. Meanwhile, the main plunger 21 has coasted downwardly during the initial part of its stroke at a rapid traverse speed, withdrawing sumcient iluid through the surge valve 49 from the surge tank 45.

When the pressure within the hydraulic circuit builds up to a predetermined amount, as determined by the resistance of the work-piece to the pressing operation, the uid pressure within the chamber |28 of the pump (Figure 5) forces the annular piston |29 downward and opens the normally closed switch .|54. This breaks the holding circuit of theY magnetic switch 12 by' severing the connection between the lines 230 and 23|. Accordingly, the blades 2|4, 2|2 and 2|3 disengage their contacts and the` solenoid 1| becomes deenergized. The armature thereof is pulled upward under the influence of the spring 81 upon the linkage connected thereto.

The control valve 2 now occupies its third position (Figure 12) until the pressure has been released from the main cylinder through the pipe .line 81 and past the choked aperture |84 in the control valve 2,' the pump discharge being automatically by-passed during this period, in the manner previously described.

The control valve now shifts to its fourth position (Figure 13), andthe return movement of the platen takes place under the inuence of the pressure fluid entering the pull-back cylinders which is opened by the pressure fluid along the 35. Mea while, the action of the surge valve,

line 50 from the pull-back line 4|, enables the uid within'the maint-cylinder 26 4to be rapidly discharged into the surge tank 45.

When the platen 3| approaches the end of its return stroke4 the platen arm 54 will engage the collarv 55 (Figure 2) and lift the control rod 53, causing the collar 5| thereon to engage and close the normally open limit switch 62. This reenergizes the operating coil of the magnetic switch 12 by current proceeding from the line 2||, through the line 223, the resistor 225, the line 226, the selector switch 219, the line 221, the

operating coll of the magnet switch 12, the line 228, the branch line 232, the limit switch 62, the

une zsathe'seieetor swiich 22o, the unes 234,.

235 and 230, the pump-operated kswitch |54, the line,23|, the normally closed reverse switch I 2|8 and the line 224 leading to the power line 2 I8.

The second closing of the switch blades 2|2, 2|3 and 2|4 again energizes the solenoid 1| to startv another pressing stroke and at the same time energizes the holding circuit of the magnetic switch 12 through the switch blade 2|4,

in the manner previously described (Figure 9).

'I'he operating coil of the magnetic switch 12' thus remains energized through this holding vcircuit even whenthe limit switch 2 is opened by its release, because of the downward motion of the collar 6| upon the control rod 53, as permitted by the downward motion of the platen 3|. The press will thereafter continue automatically to execute an indeterminate number of pressing and return strokes without halting and without the necessity, on the part of the operator, of depressing the forward switch 2|1'for each stroke.

To cause the press to operate under semi-automatic control, whereby :fthe platen performs a workingstroke, reverses itself and comes to rest at the end of a return stroke, the selector switch 228 is opened by y the operator. 'Ihe selector switch 2|9, however, is kept closed. 'Ihe operator starts the operation of the forward stroke, as before, by closing the forward switch 2|1. The platen 3| will then execute a working stroke, in the manner previously described in connection with the completely automatic operation. As the selector switch 220 is open, however, the closing of the limit switch 62 at the end of the return stroke is ineffective tofreenergize the operating coil of the magnetic switch 12. The solenoid 1| therefore remains unenergized and ineffective to start another working stroke, Accordingly, the

platen 3| continues to move upward until the platen arm 54 engages the collar 55 and lifts the control rod 53, thereby shifting the control valve 2 to its fth position, shown in Figure 14. By the action of the control valve 2 in its fifth position, as previouslydescribed, the platen 3| comes to rest at the top of its return stroke and is held in place by the action of the control valve in preventing the tripping of the platen, as described above.

When it is desired to cause the press to execute another semi-automatic cycle of operations, the operator again depresses the forwardswitch 2|1. The foregoing cycle of operations, then repeats itself, and the platen moves downward, executes a has occurred, the operator depresses the normally actuated switch |54, and deenergizes the holding circuit of the operating coil of the magnetic switch 12 by'breaking the connection between' the line 23| and the line 224 leading to the power line 2 lll.'

The consequent opening of the magnetic switch blades 2|2 and 2 I3 deenergizes the solenoid lli, whereupon the spring 97 shifts the control valve 2 -to its third position or reversing position, as

shown in Figure 12. Under completely automatic operation the closing of the limit switchL 52 by the raising of the control rod 53 again' energizes the solenoid 1l and causes the platen 3| to reverse at the top of its return stroke, thereby executing another pressing stroke. Undersemi-automatic operation, however, the action of the platen arm 54 a'nd collar 5v5 shifts the control rod 53 to cause the control valve 2 to shift to its fifth position (Figure 14), whereupon the platen comes to rest at the top of its return stroke, as described above. The reversal of the press by the use of the reverse switch Zi, in eiiect, enables the operator to control the press platen manually by electrical means.

To render the electrical apparatus entirely ineffective, the selector switch -2l9 is opened. This opens the circuit between the line 226 running to the power line 2| I, through the resistor 225 and the line 223, and thus entirelyprevents the energization of the operating coil of the magnetic switchflZ under any circumstances. The manual control lever 56 may then be employed to move the control rod 53 up or down and operate the control valve 2 through the linkages connecting the valve rod I6@ with the centrol rod 53, In this manner the operator may control the action of the` press by purely mechanical means, and cause it to execute pressing and return strokes of any desired length.

If positional reversal of the platen upon the working stroke is desired, it may be accomplished by replacing the pump-actuated switch |54 by a normally closed limit switch similar to the limit switch 62 and actuated by a collar upon the control rod 53, similar to the collar 6|, and turned in the opposite direction. Ii .both methods of reversal are desired. this normally closed limit switch may be placed in parallel with the pumpactuated switch |56 between the lines 230 and 23| with a single-pole double-throw selector switch to determine which method of control will be used.

I desire to comprehend within my invention such modiiications as may be embraced within my claims and the scope of myy invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

l. In a hydraulic press circuit with an electromagnetically-operated control valve, a variable delivery pump having a dow-controlling member in the pump, movable to regulate the delivery of the pump in response to the pressure in the hydraulic press circuit, and an electrical circuitcontrolling device arranged to be operated by the motion of said flow-controlling member and connected :to control the energization ofthe electromagnetically-operated control valve. j

2. In a hydraulic press circuit with an electromagnetically-operated control valve, a variable delivery pump having a movable flow-controlling member in the pump, pressure-responsive means for shifting said flow-controlling member to reduce the discharge of said pump in response to the attainment of a predetermined pressure in the hydraulic press circuit, and an electrical circuit-controlling device arranged' to be operated by the motion of said flow-controlling member and connected to control the energization of the electromagnetically-operated control valve.

3. In a hydraulic press circuit with an electromagnetically-operated control valve, a variable delivery pump having a movable flow-controlling member in the pump, movable to regulate the delivery of the pump in response to the pressure in the hydraulic press circuit, pressure-responsive means for shifting said flow-controlling member to reduce the discharge of said pump in response to the attainment of a. predetermined pressure in the hydraulic press circuit, and an electrical switch adapted to be operated by the motion of said flow-controlling member and connected to control the enerization of the electromagnetically-operated control Valve.

4. In a hydraulic press circuit with an electromagnetically-operatedl control valve, a variable delivery pump having a movable flow-controlling member in the pump movable to regulate the delivery of the pump in response to the pressure in the hydraulic press circuit, pressure-responsive means for shifting saidow-controlling member to reduce the discharge of said pump in response to the attainment of a predetermined pressure in delivery pump having a movable now-controlling member in the pump movable to regulate the delivery of the pump in response to the pressure n the hydraulic press circuit, pressure-responsive means for shifting said flow-controlling member to reduce the discharge of said pump in response to the attainment of a predetermined pressure in the hydraulic press circuit, an electrical circuitcontrolling device arranged to be operated by the motion of said dow-controlling member and connected to control the energization of the electromagnetically-operated control valve, and means for varying the amount of the predetermined pressure at which said pressure-responsive means becomes operative.

6. In a hydraulic press circuit with an electromagnetically-operated control valve, a variable delivery pump having a movable flow-controlling member in the pump, movable to regulate the delivery of the pump in response to the pressure in the hydraulic press circuit, pressure-responsive means for shifting said flow-controlling member to reduce the discharge of said pump in response to the attainment of a predetermined pressure in the hydraulic press circuit, electrical switch means arranged to be engaged by said flow-controlling member upon the attainment of said predetermined pressure and connected `to control the delivery pump having a shift ring in the pump adapted {to vary the discharge of said pump, an electrical switch connected to control the energization of the electromagnetically-operated control valve, a pressure-responsive device for shifting said shift ring to its neutral position to terminate the discharge of said pump in response to the attainment of a predetermined pressure in the hydraulic press circuit, and means interconnecting said shift ring and said switch to operate said switch upon the attainment of said predetermined pressure.

8. In a hydraulic press circuit, a variable delivery pump having a ow controlling member in the pump, a valve arranged to control the direction of delivery of fluid from saidvpump to the press circuit, a solenoid adapted to actuate said valve, a relay connected to said solenoid to control its energization, and a switch in series with the coil of said relay arranged to be actuated by o0 the flow-controlling member of said pump upon the attainment of a predetermined pressure in the press circuit so as to actuate said valve and thus to reverse the delivery of said pump.

9. In a hydraulic press circuit with an electromagnetically-operated control valve, a uni-directional variable delivery pump having a flowcontrolling member in the pump movable to regulate the delivery of the pump in response to the pressure in the hydraulic press circuit, and an 2 electrical circuit-controlling device arranged to be operated by the motion of said now-controlling member and connected to control the energize.- tion of the electromagnetically-operated control valve.

l 10. In a hydraulic press circuit with an electromagnetically-operated press reversing valve, a variable delivery pump having a flow-controlling member in the pump movable to regulate the de- [delivery pump having a now-controlling member `in the pump movable to regulate the delivery of the pump in response to the pressure in the hydraulic press circuit, said pump being connected to said electromagnetically-operated control valve so as to deliver through it to said press circuit, and an electrical circuit-controlling device arranged to be operated by the motion of said how-controlling member and connected to control the energization of the electromagneticallyoperated control valve.

l2. In a hydraulic press circuit with an electromagnetically-operated control valve, a variable delivery pump having a ow-controlling member in the pump, movable to regulate the delivery of the pump in response to the pressure in the hydraulic press circuit, and a normally closed electrical switch arranged to be opened by said owcontrolling member and connected to control the energization of the electromagnetically-operated control valve. v

, WALTER ERNST.

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