US2283358A - Electrically controlled hydraulic press - Google Patents

Description

P. E. FLOWERS ELEOTRICALLY-CON TROLL ED HYDRAULIC PRESS Filed Aug. 31, 1939 6 Sheets-Sheet 1 k S E m 5 w m w N 6 PM mN Om.

NM Wm Arromvarrs May 19, 1942. P. E. FLOWERS I ELECTRICALLY-CONTROLLED HYDRAULIC PRESS s Sheets-Sheet 5 Filed Aug. 31, .1959

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ATTORNEYS y 942. P. E. FLOWERS 2,283,358

ELECTRICALLYCONTROLLED HYDRAULICIPRESS 6', Sheets-Sheet 6 lure/Woe #404 mm;

TTOK/VEYS Patented May 19, 1942 UNITED STATES, PATENTFOFFICE ELECTRICALLY eefifms nrnaaomc Paul E. Flowers, Mount Gilead, Ohio, assignor to The Hydraulic Development Corporation, Inc., Wilmington, DeL, a corporation of Delaware Application August 31, 1939, Serial No. 292,934

12 Claims.

This invention relates to presses; and in particular, to electrically-controlled hydraulic presses.

One object of thisinvention is to provide an electrically-controlled hydraulic press with its electrical and hydraulic units assembled in compact housings so as to conceal them and protect them from dust and other damaging influences.

Another object is to provide an el ectrically controlled hydraulic press having its electrical and hydraulic unitsmounted in inclosed housings in the head and bed ofthe press, respectively, and arranged in compact cessible assemblies.

Another object is to provide a hydraulic press with a head .member and a bed member, one of these members having the principal hydraulic yet easily ac- Q 7 units mounted theron and inclosed by a housing,

and the other member having the principal electrical units similarly. mounted and inclosed.

Another object is to provide ahydraulic press having a pump and a flow-control member actuated by a press control rod, whichin turn,

is under the control of a solenoid mounted in the bed of the press. I

Another object is to provide a hydraulic press control system, as set forth in the preceding para r ph. wherein the solenoid is under the control of one or more limit switches, means being provided to restrict the efiectiveaction of the switch to one direction only 6r actuation.

Another object is to provide a hydraulic press 7 control system including an electrical circuit a r selectively efiecting semi-automatic and in l automatic'opel'ation otthe press ramunder the control of a limit switch, which is effective only to change the energization of the circuit by actuation ill one direction and not. in the opposite Another object is to providea hydraulic press control system having an .electrical control circuit for selectively efiecting semi-automatic and full automatic operation of the press, together with a pairoi limit switches so arranged as to alter the tion of the electrical circuit by actuationin one direction but not in the o posite Figure 1 is a perspective view of a commercial form of pres embodying the control system of the present invention.

Figure2isa'. 'cview,mainly in section, showing the hydraulic circuit for operatlllgthepress showninFigure 1.

Figure MS a side elevation of the press shown in Figure 1, with the housings removed or cut away to disclose the operating mechanism therebeneath.

Figure 4 is an Figure 3. showing the press control rod and the; associated limit switches .in' a position wherein the press-operating solenoid is energized for producing aforward stroke of the press.

Figure 5 is a view similar to Figure 4, but. with the solenoid deener'gized and the press control rod pushed down for efiecting a return stroke of the press ram.

Figure 6 is awiring diagram of the electrical control circuit employed in the press of Figures 1 to 5, inclusive.

Figure 7 is an enlarged front elevation, partly in secticn, of the bed'of a press and a modified control system whereby a single limit switch,

is actuated in but one direction of travel of the of the switch-actuating mechanism of Figure '1,

showing the limit switch being actuated on the ip-stroke of the press control rod.

Figure 10 is a view similar to Figure 9, but

,showing the limit switch being avoided by the switch-actuating mechanism on the down-stroke of the control rod. v

Figure 11 is a side elevation, partly in section,

' showing the hand control lever and its associated mechanism for actuating the press control rod by hand. v w

Figure 12 is a diagram of the electrical circuit associated with the press ofFigures 7 to 11, in-' elusive. General arrangement In general, the hydraulic-press control system of this invention is associated with a press having a reversible hydraulic motor, a source of pressure fluid and a flow-control member, whereby the presui'e fluid is reversibly distributed. to

the motor. The control rod of the press which I shifts the flow-control-member. associated with the source of pressure iluid, such as 'a pump, is

actuated by a solenoid placed in the base of the press. Asoclated with the solenoid is a limit switch system which is rendered effective to energize the solenoid in but one direction of motion of the control rod. In' one embodiment of the invention (Figure 1 to 6) this uni-directional actuation is-efiected by the use of a pair of limit switches, whereas inthe modification (Figures enlarged view of a portion of' 'z to 12) this is effected by mechanical means engaging a single limit switch.

,found advisable to do this because of the presence of dust or other damaging substances, which injure these accessories. It has also been found advisable in recent times to inclose these agcessories within housings in order to present a more compact appearance and also to prevent the accidental damage of these accessories by contact with external objects. At the same time the operator is protected from injury by the presence of these housings.

Hitherto, the flow-controlmember of the reversible variable delivery pump (in a closed circuit) or the. valve member of the main control valve (in an open circuit) has been shifted in at least one direction by an electrical solenoid, shifting in the opposite direction having been usually accomplished by means of I a spring. Previously the solenoid was mounted in a position adjacent the pump, or valve, but this position was remote from the switches, magnetic for the press, such as the back plungers I! connected at their upper ends to the press platen I8. The latter is connected to the main plunger I3, reciprocable in the main cylinder 20, only the lower end of the latter being visible. Mounted upon the press head I2 is a fluid container or surge tank 2| having'a gauge 22 for indicating the level of the oil or other working liquid therein. The press head |2 is provided with a shelf 23 upon which a housing 24 is supported. The housing 24 serves to receive and inclose certain of the hydraulic apparatus pump and driving. motor. A hand lever 25, mounted upon a shaft 26 supported in the press bed l0, serves for the manual control of the press when the electrical "control system is not in operation.

contactor and other electrical units additionally I associated with the control circuit. This was.

particularly true where the pump and other hydraulic units .Were mounted upon the press head out of reach of the operator.

The present invention enables the solenoid to be mounted in the bed of the press adjacent the othervelectrical apparatus of the control circuit.

Means, however, is provided for controlling the solenoid so that it is energized in but one direction of motion of the control rod. In one form of the invention (Figures 1 to 6) the solenoid is under the control of a main limit switch and an auxiliary limit switch, the latter merely conditioning the circuits of the main limit switch for operation. These two limit switches are operated by a cam upon the press control rod so that full automatic operation of the press is brought about when the platen reaches the end of its retraction stroke and raises the control rod so as to actuate the limit switches and reenergize the solenoid. In the modified form of the. invention (Figures 7 to 12) a single main limit switch is employed for effecting full automatic operation and reenergization of the solenoid at the end of the return stroke of the platen, actuation of, this ,limit switch in one direction only being insured by a special mechanical arrangement associated with the press control rod. Either of these forms of the invention enables the solenoid to be concealed within the base of the press adjacent the other electrical apparatus so that short wiring is permitted and a more compact distribution of the electrical units obtained.

Ewternal construction of press Referring to the drawings in detail, Figure 1 shows a perspective view of a press embodying either ofthe control systems of this invention. This 'press consists of a bed |-0 connected by strain rods H to a head l2. The bed In is inclosed by a housing |3 having a closure or door Hydraulic circuit of press The hydraulic circuit for actuating the press is shown diagrammatically in Figure 2. The platen I8 is connected on its upper side to the main plunger l9 reciprocating in the main cylinder 20, and is connected on its lower side to the pushback plungers l1 reciprocating in the push-back cylinders l6. Pressure fluid for operating these cylinders and advancing and retracting the respective plungers is provided by the pump 21, which may be of any suitable type. The pump 21 withdraws fluid through the suction line 28, and discharges pressure fluid through the line 29 leading by way of the check valve 30 to the main four-way control valve 3|. A branch line 32 also leads from the line 29, by way of the pressure relief valve 33 and check valve 34, to the interior of the surge tank 2|, and serves to discharge pressure fluid when the pressure delivered by the pump 2'! exceeds the setting of the pressure relief valve 33.

The four-way valve 3| is provided with a valve rod 35 connected to the press control rod 36, which carries a collar 31 adapted to be engaged by the platen arm 38 extending laterally from the platen H3. The control rod 36 also carries a ca'm'39 adapted to engage and actuate the contact portions 40 and 4| of the automatic restarting switch 42 and the circuit-conditioning switch 43. The control rod 36 terminates at its lower end in a connection 44 joining it to one end of a lever 45, which is pivotally mounted as at 46 to a bracket 47 mounted on thepress frame, and having a pivotal connection 48 with the armature 49 of a push type solenoid 50. The construction shown diagrammatically in Figure 2 is illustrated more in detail in Figure 3. r

The four-way main control valve vided with discharge conduits 5| and 52, and an exhaust conduit 53 with a check valve 54. The exhaust conduit 53 leads to the interior of the surge tank 2|, whereas the discharge conduit 5| leads to the upper end of the main cylinder 20. The discharge conduit 52, on the other hand, leads to the lower ends of thepush-back cylinders l6, and has a branch conduit 55 leading to the operating chamber 56 of the surge valve 51 mounted in the upper end of the main cylinder 20. A pressure-responsive switch or tonnage control 58 is connected by the conduit 59 to the upper end of the main cylinder 20 and by the ex- ?augt conduit. 60 to the interior of the surge Electrical control circuit of press The electrical control circuit for controlling t e various movements of the press (Figure 6) includes a motor 6| operatively connected to the 3| is propump 21 and energized by the lines 82, 83 and 84 from the branch power lines 85, 88 and 81, by way of the switch blades 88, 89 and 18 attached, with the switch blade II, to the armature 12 of the motor contactor I3 having an operating coil I4, one end of which is connected by the line I5 tothe branch power line 85. The branch power lines 85, 86 and 81 are connected, respectively, to the main power lines 18, 11 and I8. ,The switch blade II of the contactor I3 serves as an interlock for providing sustained energization of the motor contactor operating coil 14 when the momentary motor sta g switch or push-button switch I9 is released after being depressed by the operator. For this purpose the line 88 runs from one pole of the switch blade "to one pole of the motor starting push-button switch I9, and thence to one pole of the motor stopping'pushbutton switch 8I.'

The starting push-button switch 19 is'normally open and the stopping push-button switch 8| normally closed. The remaining pole of the latter is connected by the line 82 to the remaining end of the motor contactor operating coil I4. The remaining pole of the motor starting push-button switch I9 is connected by the line 83 to the remaining pole of the switch blade I I, and thence to the branch power line 88. As a consequence, when the motor push-button starting switch I9 is momentarily depressed by the operator, the

consequent energization closes the magnetic contactor 18 and energizes the motor 8I. This starts thepump in operation and supplies pressure fluid to the press circuit.

*At the same time, the switch blade II interconnects the lines 83 and 88 to bridge the contacts of the motor starting push-button switch I9 so that the energization of the operating coil 14 is maintained even when the push-button switch 19 is released by the operator.' If it is desired to stop the motor the operator merely depresses the normally closed push-button stopping switch 8|.

. The press control circuit is energized from the branch power lines 84 and 85, and includes a main magnetic contactor 88, the solenoid 58, an auxiliary magnetic contactor 81, the combined momentary contact 89 and a forward'push-button switch 98. The circuit also includes the limit switches 42 and 43, previously mentioned, for controlling the fullautomatic operation of the press, together with the pressure-responsive switch 58. Also provided is an oiltemperature limit switch 9|, which is controlled by a thermostat to open when the temperature of the oil, or other working fluid,- exceeds the setting. of the thermostat. Insuch event the opening of the switches terminates the automatic operation of the press. A position-responsive limit switch 92, operated by the platen, is also provided as an additional safety feature for preventing overrun, of the platen. The combined momentary contact and selector switches 88- and 89 in their details and of themselves are described in the copending application of Walter Ernst, Ser. No. 292,931,

filed August 31, 1939.

Semi-automatic operation occurs when the press platen makes a forward stroke, reverses, makes a retraction stroke and then comes to a halt. Full automatic operation, on the other hand, occurs when the press platen makes a forward stroke, reverses, executes a retraction stroke and halts only momentarily before beginning another forward stroke, thereby repeating an indefinite number of working cycles until halted by the operator, orby one of the safety switches. The switch 89 is normally engaged in a position designated Automatic, but it may be shifted into the reverse position indicated by the dotted lines of the operating coil I4 in Figure 6. The position marked.Hand is .-merely for the purpose of deenergizing the entire control circuit so that the press is controlled by the shifting of the hand lever 25.

The combined switch 88 is connected by the line 93 to one pole of the forward push-button switch 98, the opposite pole of which is connected by the lines 94 and 95 to one pole of the automatic restarting switch 42 and tothe branch power line 88, respectively. From the opposite pole of the automatic restarting s tch 42 the line 98 runs to one pole ofpthe auxiliary contactor 81. The latter is provided with switch an armature 99 actuated by the operating coil I88. From the opposite pole of, the switch blade 91 the line I8-I runs to one of the full automatic contacts of the combined switch 88, from the remaining contact of which the line I82 runs to one of the interlock contac I of the main contactor 88. .The auxiliary contactor 8l is energized bythe line I83 connectedto the branch power line 84, and its opposite end is connected to the line I84 running to one pole of the'circuit-conditioning switch 48, the connected to the line I85. The closing of the contactor 81 thus closes the circuit between the lines 98 and 'I8I, through the switch blade 91, and between the lines I84 and I85 by way-of the interlock switch blade 98.

Beyond the circuit-conditionnig switch 43 the line I88 runs to a junction-with the line I81 leading from one of the automatic poles of the combined switch 89 to one end of the operating coil I88 of the main magnetic contactor, the opand selector switches 88 and tonnage control limit The switch 88 normally rests in the solid-line position designated .Forward,

moved into the Semi-automatic position or Full automatic position and locked in these positions at the will of the operator. Thus the switch 88 serves not only as a push-button switch .but also as a selector switch for selecting either semi-automatic or full automatic operation.

but it may be to the branch power line 84,

posite end of which is connected by the line I89 to the same pole to which the line I82 is connected, namely, an interlock pole engageable by the interlock switch blade H8. The opposite pole of the latter is connected by the line III and by the line I I2 to an automatic pole of the combined switch 89 by way of the resistance II3 andpilot light H4. The main magnetic contactor 88 is also provided with switch blades H5 and II8 mounted on the same armature III upon which the interlock blade H8 is mounted, and operable to connect and disconnect the solenoid 58 from the branch power lines 84 and 85'.

. Operation In the operationof the press shown in Figures -1 to 6, inclusive, the operator momentarily de- I9, thereby 13. through the interlock switch lade II maintains the energization of the motor I when the pushbutton switch I9 is released. The operation 01 switches 88 and 98 with his two-hands, thus problades 91 and 98, upon other pole of which is The previously described holding circuit viding a safety feature preventing injury to his hands by inadvertently starting the press before he has removed his hands from the press.

The shifting of the switch 88 to the semi-automatic position energizes the main contactor 86, and as a consequence energizes the solenoid 50. The energization of the contactor coil I08 is accomplished by way of the lines I03 and 95, the forward push-button switch 90, the line 93, the combined switch 88, the lines I 02 and I09, the line I01, thecombined switch 89, the limit switch 92, the oil temperature limit switch 9|, the tonnage control switch 58 and the line II 8 to the branch power line 85. The energization is maintained by the closing ofthe interlock switch blade IIO upon its contacts.

The energization of the solenoid 50 pushes its armature 49 downwardly and raises the control rod 36 so as to shift the valve rod 35 into a position where the pump 21 will deliver pressure fluid to the top of the main cylinder 20 through the line The main plunger I9 and platen I8 move downwardly and engage the workpiece. When the resistance thus built up exceeds the pressure setting of the tonnagecontrol switch 58, the latter opens the circuit in the line II 8. This deenergizes the operating coil I08 of the main magnetic contactor 86 and consequently deenergizes the solenoid 50. A spring II 9 (Figure 3) at the upper end of the valve rod 35 then forces the control rod 36 downwardly into the position shown in Figure 5, thereby closing the circuit-conditioning switch 43.

In Figure 3 the switches 42 and 43 and cam 39 are shown in the neutral position of the press, where the platen I8 is halted at the upper end of its stroke. In Figure 4 the control rod 36 and cam 39 have been raised from the neutral position of Figure 3 but whilethe automatic restarting switch 42 has been shifted by the cam 39 no change occurs in the electrical circuit because the circuit-conditioning switch 43 has not yet been engaged and has not prepared the circuit for energization by the automatic restarting switch 42. In other words, the closing of the circuit-conditioning switch 43 is a necessary preliminary to the effective operation of the automatic restarting-switch 42.

The deenergization of the solenoid 50 permits the spring II 9 to force the control rod 36 downwardly into'the Figure 5 position, closing the circuit-conditioning switch 43,. as previously as stated. The consequent shifting of the main control valve 3| reverses the flow of fluid by discharging pressure fluid into inders I6 and exhausting fluid from the upper part of the main cylinder 20 by way of the conduit 5|. The main plunger I9 and platen I8 then rise, under the urge of the push-back plungers I1, until the platen arm 38 engages the collar 31 and lifts the control rod 36 and valve rod 35 as the platen I8 nears the upper end of its retraction stroke. The lifting of the valve rod 35 shifts the valve 3| into its neutral position, whereby the discharge of the pump 21 is bypassed back to the surge tank 2|.and fluid is held in both the main cylinder 20 and push-; back cylinders I6. The main platen I8 thus comes to a halt at the upper end of its retraction stroke.

If full automatic operation is desired the'operator, as before, depresses the combined switch 88 combined switch 88 to its full automatic position by a locking device which looks it in that the push-back cyland the forward switch 90, but returns the tween the lines 96 and IOI.

position. Under these circumstances the platen I8 and main plunger I9 execute a forward stroke lowing the deenergization of the solenoid 50, now

depresses the automatic restarting switch 42 as the control rod 36 is lifted by the platen arm 38 engaging the collar 31.

The closing of the circuit-conditioning switch 43 (Figure 6) immediately energizes the auxiliary contactor 81 by way of the line I03, the operating coil I00, the line I04, the switch 43, the lines I06 and I01, the combined switch 89, the limit switches 92, 9| and 58 and the line H8. The consequent closing of the interlock switch blade 98 closes a holding circuit around the circuit-conditioning switch 43 by way of the lines I04 and I05 so as to maintain the energization of the auxiliary contactor 81 when the circuitconditioning switch 43 is released by the cam 39 on the upward stroke of the press control rod 36. The closing of the magnetic contactor 81 causes its switch blade 91 to close the gap be- When the cam 39 closes the automatic restarting switch 42 thereafter, the circuit is completed from the branch power line 84, through the lines I03, 95 and 94,

the now closed. switch 42, the line 96 the switch blade 91, the line IOI, the combined switch 88, the lines I02 and 09, the main contactor operating coil I08, the line I01, the combined switch 89, the limit switches 92, 9| and 58 and the line I-I8to the branch power line 85. This reenergizes and recloses the main contactor 86 and consequently reenergizes the solenoid 50. The latter again pushes its armature 49 downwardly to raise the control rod 36 and shift the valve 3| to a ram-advancing position. The main plunger I9 then executes another forward stroke, and

4 control rod 36. trol rod 36 is provided, as before, with a connecautomatically reverses itself and returns in the manner previously described, continuing to execute an indefinite number of working cycles until halted by the operator or by one of the safety switches.

Thus the provision of the circuit-conditioning switch 43 permits the automatic restarting switch 42 to be efiective to reenergize the main contactor 86 and solenoid 50 solely upon the upward' stroke of the press control rod 36," and not upon the downward stroke thereof. This feature permits the solenoid 50 to be placed within the housing I3 (Figure 3) along with the other electrical apparatus, and thereby concentrates the electrical apparatus in one location.

Modified construction The modification shownin Figures 7 to 12 is similar to the form shown in Figures 1 to 6 as regards the press construction generally. The press bed I0 is provided'with a movable carrier I20 mounted upon a cushioning plunger I 2|, reciprocable in a cushioning cylinder I22. The bed is also provided with a hand lever I25 mounted upon a shaft I26, carrying a yoke arm I21 (Figurell) engaging a collar I28 upon the press The lower end of the press con tion 44 pivotally attached to 'alever I29 having its outer end pivotally mounted upon the pin I30 in the anchor rod I3I, the upper end of which is secured by the screw I32 to the press bed III.

The inner'end of the lever I29 carries a pair of spaced plates I33 having a pivot pin I34 pivotally supporting a latch I35 (Figures 7 and 8),

one end of which engages a stop portion I36 upon the lever I29 (Figures. 9 and 101. The spaced plates I33 also carry a pivot pin I31, to which is attached the link I33 pivotally connected to the armature I {of a pull type solenoid I40. The latter is mounted upon the prem bed (Figure '7). The cushioning cylinder I22 also serves to support a single automatic restarting switch I42 having a contact portion I4I engageable by the outer end of the latch I when the link I38 is pulled upward by the energization of the solenoid I40 (FigureQ). When the solenoid is deenergized, however, and the spring I I9 onthe upper end of the valve rod 35 forces the press control rod 36 downwardly (Figure .10), the latch I35 tilts and slips past'the contact portion I4I of the switch I42 without actuating it. In

this manner the automatic restarting switch I42 is actuated only upon the upward stroke of the press control rod 36,'but is not actuated upon the downward stroke thereof.

Modified electrical circuit The modified electrical control circuit (Figur .12) for the modification shown in Figures 7 to 11 is similar to the control circuit shown in Figure 6, except that the auxiliary contactor 81, the circuit-coiiditioning switch 43 and the associated lines I05, I06, I04 and I03 have been eliminated.

' The line96 is thus directly. connected to the line IN. The solenoid I40,- however, is of th pull type, whereas the solenoid (Figure 6) is of the push type.

. Operation The semi-automatic operation of the modification shown in Figures '1 to 12 is similar to that of the press circuit shown in'Figures '1 to 6. In full automatic operation, however, when the combined switch 88 has been shifted zinto its upper or full automaticposition, the automatic restarting switch I42 is closed by the lifting of the press control rod 36 when the platen arm 30 ly after the preceding retraction stroke. .When

the press platen has arrived at th end of its forward stroke and the pressure-switch or tonnage control 56 deenergizes the solenoid I40, the consequent pushing down-of the press-control rod 36 by the spring IIS does not affect the automatic restarting switch I42 because the latch I35 merely tilts about its pivot (Figure 10) and slips harmlessly past the contact member I4I thereof.

In both of theforegoing forms of press controlcircuits an open circuit employing a pump 21 and a four-way reversing valve 3I .has been illustrated. It will be understood, however, that the press control rod 35 may be connected through appropriate mechanism to the flow-control member of a reversible variable delivery pump so that the pump itself is reversed upon the raising of the control rod 30.

It will be'understood that I desire to com rehend within my invention such modifications as come within the scope of the claims.

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

1. In a hydraulic press control system, the combination with reversible hydraulic motor means having a reciprocable ram and a source of pressure fluid therefor with a flow-control member for reversibly controlling the distribution of pressure fluid to said hydraulic motor means, of electrical means for actuating said flow-control member, a press control element interconnecting said flow-control member and said electrical means and being engageable by said ram, said press control element being adapted to vary the position of said flow-control member,

a circuit energization controller connected to control the energization of said electrical means and operable by said control element, and means for rendering said controller effective to influence the energization of said electrical means in only one direction of motion of said control element for automatically starting a new working stroke at the end of the retraction stroke.-

2. In a hydraulic press control system, the combination with reversible hydraulic motor means having a reciprocable ram and a source 'of pressure fluid therefor with a flow-control member for reversibly controlling the distribution of pressure fluid to said hydraulic motor means, of electrical means for actuating said flow-control member, a press control element positively connected wih said flow-control member and adapted to be engaged and moved by said ram, 1

said press control element forming a lever arm in a linkage interconnecting said electrical means and said flow-control member, a circuit energization .controller connected to control the-energization of said electrical means and operable by said control element, and means for'activating said circuit energization controller in only one direction of motion of said control element for automatically starting a new working stroke at the end of the retraction stroke.

3. In a hydraulic press control system, the combination with reversible hydraulic motor means having a reciprocable ram and.a source of pressure fluid therefor with a flow-control member for reversibly controlling the distribution of pressure fluid to said hydraulic motor means, of electrical means for actuating said flow-control member, a press control element connected. to said flow-control member and adapted selectively to move in unison with the latter in one or the other direction, said press control element being engageable by said ram, a circuit energization controller connected to control the energization of said electrical means, and a circuitconditioning device in circuit with said controller and engageable by said press control element for conditioning said controller for energizing said electrical meansin response to I the motion of said press control element in only one direction for automatically starting a new working stroke at the end of the retraction stroke.

4. In a hydraulic press control system, the combination with reversible hydraulic motor means having a reciprocable' ram and a source of pressure fluid therefor with a flow-control member for reversibly controlling thedistribution of pressure fluid to said hydraulic motor means, of electrical means for actuating said flow-control member, a press control element positively connected to said flow-control member -flow-control member, a

- flow-control member, a trol element positively interconnecting said flowcontrol member and said electrical means and ram, a circuit energizaand said electrical means, said press control element being engageable by-said ram, a circuit energization controller connected to control the energization of said electrical means, and a circuit-conditioning device in circuit with said controller and engageable by said press control element for conditioning said controller for energizing said electrical means; in response to the motion of said press control element in only one direction, forautomatically starting a new working stroke at the end of the retraction stroke said circuit controller being ineifective to alter the energization of said electrical means in the opposite direction of motion.

5. In a hydraulic press control system, the combination with reversible hydraulic motor means having a reciprocable ram and a source of pressure fluid therefor with a flow-control member for reversibly controlling the distribution of pressure fluid to said hydraulic motor means, of electrical means for actuating said flow-control member, a press control element connected to said flow-control member so as to be reciprocable therewith and engagable by said ram, a circuit energization controller connected to control the energization of said electrical means and engageable by said control element in both directions of motion thereof, and means for rendering said controller electrically effective in only one direction of motion of said control element, said source of pressure fluid and said flow-control member being disposed near one end of the press and said electrical means near the other end of the press, and said flow-control member and said electrical means being press control element.

6. In a hydraulic press control system, the combination with reversible hydraulic motor means having a reciprocable ram and a source of pressure fluid therefor with a flow-control member for reversibly controlling the distribution of pressure fluid to said hydraulic motor means, of electrical ,means for actuating said press control element postivelyconnected on one hand to said flow-con trol member and on the other hand to said electric means, said press control element being engageable by said ram, a circuit energization controller connected to control the energization of said electrical means and engageable by said control element in both 'directions'of motion thereof,

interconnected by said and means for rendering said controller elec-s trically effective in only one direction of motion of said control element, said electrical means comprising a solenoid endof the press from said flow-control member.

7. In a hydraulic press control system, the combination with reversible hydraulic motor means having a reciprocable ram and a source of pressure fluid therefor with a flow-control member for reversibly controlling the distribution of pressure fluid to said hydraulicmotor means, of electrical means for actuating said reciprocable press conbeing engageable by said tion controller connected tocontrol the energization of said electrical means andengageable by said control element in both directions of motion thereof, and means connected to said press control element for actuating said circuit con-' troller in only one direction-of motion of said press control element.

8. In a hydraulic presscontrol system, the

disposed at the opposite combination with reversible hydraulic motor means having a reciprocable ram and a source of pressure fluid therefor with a flow-control member for reversibly controlling the distribution of pressure fluid to said hydraulic motor means, of electrical means for actuating said flow-control member, a press control element positively connected to said flow-control member so as to be adapted to reciprocate together therewith, said press control element being engageable by said ram and interconnecting said electrical means and said flow-control member, a circuit energization controller connected to control the energization of said electrical means and operable by said control element, and mechanical means connected to said press control element and engage able to actuate said circuit controller in only one direction of motion of said press control element.

9. In a hydraulic press control system, the combination with reversible hydraulic motor means having a reciprocable ram and a source of pressure fluid therefor with a flow-control member for reversibly controlling the distribution of pressure fluid to said hydraulic motor means, of electrical means including a movable element for actuating said flow-control-member, a press control element interconnecting said flowcontrol member and said movable element and being engageable by said ram, a circuit energization controller connected to control the energization of said electrical means and operable by said control element, and a latch mechanism connected to said press control element and arranged to actuate said circuit controller in'only one direction of motion of said press control element. g

10. In a hydraulic press control system, the combination with reversible hydraulic motor means having a reciprocable ram and a source of pressure fluid therefor with a flow-control member for reversibly controlling the distribution of pressure fluid to said hydraulic motor means,- of electrical means including a movable element for actuating said flow-control member, a press control element movablyconnected to said flowcontrol member and interconnecting said flowadapted when control member and said movable element, said press control element being engageable by said ram, a circuit energization controllerconnected to control the energization of said electrical means and operable by said control element, and a latch mechanism connected to said press control element and including a pivoting member tiltable about its pivot to slip by said circuit controller in one direction of motion of said press control element without operating said circuit controller and to controller in the opposite direction of its motion.

11. In a hydraulic press in combination, hydraulic motor means, a fluid source for supplying pressure fluid to said motor same, flow controlling means for reversibly controlling the distribution of pressure fluid to saidmotor means, a control member, relay means energized to move said control member, said control member being positively coonnected with and the retraction stroke of said motormeans and means relay means for preventing energization of said by said switch means before said engage and operate said circuit 1 means to actuate the a movable element of said relay means and forming a link in a lever system introlling means, a reciprocable control member 1 positively interconnecting said relay means and said flow controlling means and having cam means associated therewith, switch means adapted to control the energization of said relay means and being engageable by said cam means at each stroke of said control member, and means for preventing energization of said relay means by said switch means before said motor meanshas reached the end of its retraction stroke.

PAUL E. FLOWERS.

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