US2309944A - Platen leveling device - Google Patents

Description

Feb. 2, 1943.

P. E. FLOWERS PLATEN LEVELING DEVICE Filed June' 2l, 1941 2 Sheets-Sheet l INvENTon AUL FLO R5 MdL/L Arrosmev Feb. ZT, P E FLowl-:Rs 2,309,944

PLATEN LEVELING DEVICE Filed June 21, 1941 2 sheets-sheet 2 nm'ma MovEMENTj Enum.

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'Patented Feb. 2, 1943 PLATEN LEvnLnvG DEVICE Paul E. Flowers, Mount Gilead, Ohio, assigner to The Hydraulic Development Corporation, Inc.,

Wilmington, Dei., a corporation of vDelaware Application June 21, 194,1, Serial No. 399,169

(Cl. b-11) 18 Claims.

This invention relates to hydraulic machines and, in particular, to the correction of deections in platens of hydraulic presses which may occur during the pressing operation oi such presses.

It is an object of the invention to provide a hydraulic press, in which the press platen is so controlled that any deflections of' the platen which may possibly occur during the pressing operation remain below a predetermined value.

It is another object of the invention to provide a hydraulic press, in which any minute deflections or tilting movements of 4the platen which may occur during a pressing operation and exceed a predetermined value are instantaneously detected and corrected.

It is a further object to provide a press with a hydraulicallyadvanced press platen, in which the supply of pressure fluid for advancing the platen is controlled in response to a predetermined deviation of the platen from a plane parallel to the normal plane of the platen, i. e., the piene of the platen when the latter is in its retracted or idle position.

Another object of the invention consists in theprovision of a press having a platen with a plurality of uid operable cylinder-piston-assemblies for advancing the platens in which the supply of uid to each cylinder-piston-assembly is individually controlled in response to a predeter- The detecting and correcting device for deviations of the press platen which may occur dur- 4 ing the pressing operation comprises .substantially a reciprocable member which is in constant contact with the press platen and translates deviations ofthe latter from its normal plane to mined deviation or tilting movement of the"30 platen.

It is another object to provide a press as set forth in the preceding paragraph, in which various predetermined deviations or tilting movements of the platen automatically cause correcting movements of various extent.

It is still another object to provide a press with a plurality of double-acting plungers for advancing and retracting the press platen, in which the supply of pressure uid to the advancing side of said plungers is individually controlled in response to predetermined deviations or tilting movements of the platen, while the supply of pressure uld to the advancing sides' oi said plungers is concomitantly reversed when said deviations or tilting movements exceed a predetermined value.

Another object consists in the provision oi a hydraulic press, in which deections or tilting movements of the press platen act upon a uid operable plunger adapted to bring about a variation in the supply oi uid to a uld motor for reciprocating the press platen.

These and other objects' and advantages oi the invention will appear more clearly from the iola control cylinder-piston-assembly including a control plunger' which is constantly urged in a predetermined direction.

Deviations of the press platen translated to the said cylinder-piston-assembly cause a variation in the pressure condition prevailing in said cylinder-piston-assembly which in turn causes movement o! the control plunger in one or the other direction.

Responsive to the movement of the control plunger, a mechanism is actuated which varies the supply of fluid to `iiuld operable means for advancing the press platen in Vsuch a manner that the advancement of that portion of the press platen which is running ahead is automatically retarded, thereby allowing the platen to return to its normal plane.

Structural arrangement Referring to theV drawings in detail, the press diagrammatically shown in Figure l comprises a. press head I and a press bed 2 interconnected r with each other by strain rods 3.

The press head i comprises two cylinders 4 and 5 of substantially equal shape and dimension, in which respectively are reciprorably mounted a ram 6, l, connected to the press platen 8. The rams 6 and l are surrounded at the lower portion of the cylinders 4 and 5 by packing material 9 and l0 respectively compressed by glands Il and i2.

Mounted at the upper end in each cylinder 4, 5, is a surge valve Il. i3a, which extends into the duid reservoir or surge tank ll mounted on top of the press head l. The surge valve i9 communicates with a conduit l5 comprising a check valve l and communicating with a conduit l1,

one end of which leads to a pressure relief valve i8, while the otherend of the conduit il leads to a main cylinder release and pump ley-pass valve i9,

. The surge valve i3 and the main cylinder release and pump by-pass valve i9 do not form a part of the present invention and for a more detailed description thereof reference may respectively be had to U. S. Patent 2,193,21l8and U. S. patent application, Serial 286,063, flied July 2s, 1939, both to Ernst. I

'Ihe purpose of the surge valve i3 is to prell the cylinder l when the ram d moves downwardly by gravity, while the main cylinder release and pump by-pass valve i9 serves to relieve the pressure in the upperportion ci the cylinder d at the initiation of the retraction stroke oi the press platen 8.

Communicating with the conduit l1 is a conduit 20, one end of which leads to the lower end of the cylinder 4, while the other end leads to one side of a. reversible variable delivery pump 2| The other side of the pump 2| is connected to the conduit 22 which leads to the upper portion of the press cylinder 4. The conduit 22 is connected to a branch line 23 leading to the main cylinder releaseY and pump by-pass valve I9, and is also connected with a conduit 24 comprising a pressure relief valve 25.. The pump 2| comprises a. servomotor 26 which is supplied with pressure iluid from an auxiliary pump (not shown), and its operation is controlled by means of the servomotor valve rod 21 by moving the servomotor valve rod 21 in or out. 'I'he servo- 'motor 26 may be caused to shift the flow condirection of the pressure uid supplied by the pump 2|. The details of this servomotor control system form no part of the present invention and for a more detailed description thereof reference may be had to U. S. Patent 2,184,665 to Ernst. s

Pivotally connected with the servomotor valve rod 21 and shii'table about the pivot 28 olf -the link 29 is the link 30 which inits turn is pivotally connected to the collapsible link cylinder 3| Communicating with the end oi the cylinder 3| is a T-shaped conduit 32, one end of which leads to a check valve 33, while the other end leads to an adjustable choke valve 34. Reciprocably mounted in the link cylinder 3| is a. piston 35 connected to an armature. 38 of smaller di ameter which in its turn is connected to a link 31 passing through the end wall 38 of the cylinder 3| and pivotally connected to the arm 39. Mounted between the armature 36 and the end wall 38 is a spring 40 continuously urging the amature 36v and piston 35 away from. the end. wall 38.

Connected for instance by a screw 4| with the link 31 is a latch 42 adapted to cooperate selectively with the arm 43 or 44 of the snap lever 4 5 which is shiftable about the pivot 46. 'I'he pivot 46 is adjustable in a slot 41 of a supporting arm 48 connected, in any convenient manner, with the link cylinder 3|. The snap lever 45 comprises an arm 49 carrying a contact 50 adapted to engage a contact 5|. The contacts 50 and 5| The contact 59 is connected with a line 53 leading to the line 59, one end of which is connected to the solenoid 55 which is stationarily mounted in the link cylinder 3| and adapted, when energized, to actuate the armature 36. The other end oi the solenoid 55 is connected to the line 55 leading to the main supply line 51.

Branching o from the line 56 are lines 58,' 59 and 69 adapted respectively to be connected with lines 9|, 92 and 69 by closure of the blades 68, 69 and 96. The blades 69, 65 and 66 are carried. by the armature 91 which is continuously urged to open position by a spring 68 and is adapted to be moved into closed position against the thrust of the spring 68 by energization of the solenoid 69. One end of the solenoid 69 is connected with the line 6| and with a line 10, which in its turn is adapted by closure of the starter button 1| to be connected with the line 12 leading to the line 58. The other end of the solenoid 69 is connected to a line-v 13. which leads to a normally closed limit switch 14a, which latter is connected by line 15 with a similarly normally closed limit switch 14. 'Ihe limit switch 14 is connected with a line 16 leading to the main supply line 11. The line 16 is also connected to the line 18 leading to a normally open limit switch 19. Also connected to the limit switch 19 is a line 80 which leads to the contact 5|.

The lines `62 and 63 lead to a solenoid 8| adapted, when energized, to attract an armature 82, 'which is pivotally connected with a threearm lever, generally designated 83.v Connected with the lines 62 and 63 are lines 62a and 63a leading to a similar solenoid 8|a. The arm 84 ofthe threearm lever 83 is pivotally connected by a link 85 with the arm 39, while the arm 86 of the three-arm lever 83 is adapted to be engaged by a collar 31 adjustably mounted on a.

push rod 88 which is reciprocable in the pressv head i. The push rod 88 also carries at the lower end thereof anadustablecollar 89, adapted to be engaged by the platen arm 90.l

The press platen 8 comprises a control cylinder 9| in Jwhich is reciprocably mounted a plunger 92 surrounded by packing material 93 compressed by a. gland 94, which is connected to the platen 8 in any convenient manner. The plunger 92 connected to the reference bar 95 has alongi- Atudinal bore 96 therethrough, which registers with a bore 91 in the reference bar 95.

Reciprocably mounted in the bore 91' is a control plunger 98 surrounded by packing material 99 compressed by a gland |00. The control plunger 98 carries a cam member |0| which is adapted selectively to .close the switch 19 by l actuating its arm |02 or to close the switch |03 s by actuating its arm I 04. Thecam member |0| is also adapted to open the normally closedV is also connected by means of line ||0 with the main supply line 11. v

Communicating with the bore 911m the reference bar 951s a passageway which leads to a valve ||2 and is adapted to release air trapped in the bore 91. The control cylinder 9| communicates with the passageway ||3 provided in the platen 8 and leads to a shut-of! valve ||4 which is connected to a fluid source, for instance a hydraulic pressure pump (not shown). When the valve II4 is open, iluid passes therethrough into the control cylinder 9|. To eilect fine adjustments in the pressure prevailing in the control cylinder 9I, athreaded plunger I|5 is provided in the platen 8 and extending into the control cylinder 9I. The 'adjustment of the' threaded plunger 115 maybe eiected from the outside of the press, by turning the plunger head II6. A lock nut II1 likewise operable from the outside of the press is provided for maintaining the threaded plunger I5 mits adjusted position.

4While the detecting and correcting device and the hydraulic system so far described pertains to the ram 6 only, it is of course understood that similar means are associated with the ram 1. However, since the last mentioned means are identical with those pertaining to the ram 6, a description thereof appears to be superfluous and the corresponding parts have been numbered with the same reference numerals as those pertaining to the ram 6, however, with the additional letter a.

The reference bar 95 is connected with a plunger II8 reciprocable ln sleeves II9 provided in the press head I. Connected to the lower side of the reference bar 95, for instance by screws |20, is an upperbearing member I2I resting with its spherical surface on a ball |22 which in its turn is journalled in a lower bearing member |23 connected to the platen 8.V Normally the weight of the plunger II8 and the reterence lbar 95 will be sufficient to positively hold the upper bearing member |2| in contact with the ball |22. However, if desired, two springs |24 may be provided for securing constant contact between the upper bearing member |2| and the ball |22.

Referring to Figure 6, the structure shown therein is similar to that shown at the lower end of Figure 2. However, in contrast to the arrangement shown in the latter, the control cylinder |25, corresponding to the control cylinder 9| of Figure 2, is provided in a separate casing |26, which is threaded or otherwise detachablv connected to the press platen 8b. Furthermore, the control plunger 98 is reciprocable in the bore 96h of the plunger 92h, which is connected by a clamp ring |21 with the reference bar 95. Since in the embodiment of Figure 6 the casing |09 is connected to the casing |28, a slot |28 is provided in the casing |09 t'o allow movement of the reference bar relative thereto, while a slot |29 is provided in the casing |09 to allow movement of the valve I |2 carried by the plunger 92h and adapted to communicate with the upper portion of the bore 96h. I

Operation supposing that all parts of the press occupy the position shown in Figures l and 2, and that it is now desired to perform a working cycle.

To this end the operator actuates the starter button 1I so as to connect the line 10 with the line 12 (Figure 2). As a result thereof, current i-lows from the main supply line 51, through line blade 54, line 6|, solenoid 69, line 13, switches 14a and 14, line 16 and the main supply line 11.

Closure of the switch blades 65 and 66 establishes a holding circuit for the solenoid 8|, which comprises the main supply line 51, line 56, line 59, switch blade 65, line 62, solenoid 8|, line 63. switch blade 66, line 60 and main supply line 11 This causes energization of the solenoid 8| and also of the solenoid 8Ia, which is connected by lines 62a and 63a with the lines 62 and 63.

Energization of the solenoid 8| shifts the three-arm lever 83 in clockwise direction so that the link 31 and due to its spring connection with the cylinder 3|, also the latter is shifted toward the left with regard to Figures 1 and 2,

which in turn causes shifting movement of the 58,', starter button 1I, line 10, solenoid 69, line 13, normally closed switches 14a and 14 and line 16 to the main supply line 11. In this way the solenoid 69 is energized, thereby causing the switch blades 64, and 66 to move into closing position. Closurel of the switch blade 64 establishes a holding circuit for the solenoid 69, which comprises the main supply line 51. line 58, switch "servomotor valve rod 21 toward the right, thereby moving the pump 2| into full delivery forward stroke position. Similarly the energization oi the solenoid 8Ia moves the pump 2 la simultaneously into full delivery forward stroke position. As a result thereof, the pump 2| delivers pressure iluid through conduit 22 into the upper portion of the cylinder 4, while the .pump 2Ia delivers pressure fluid through the line 22a into the upper portion of the cylinder 5. Since, as mentioned above, the pumps 2| and 2Ia and the cylinders 4 and 5 are substantially identical, the cylinders 4 and 5 receive the same quantity of fluid from their respective pumps. Due to the withdrawal of iluid from the lower portion of the cylinders 4 and 5 through the conduits 20 and 20a respectively, the rams 6 and 1 move downwardly by gravity. Duri-ng this downward movement, the supply of iiuid from the pumps 2| and 2Ia is supplemented by fluid from the tank I4 passing through the surge valves I3 and I3a respectively. As soon as the platen or the die connected thereto engages the work piece. pressure starts to build up in the cylinders 4 and 5, which causes the surge valves |3 and I3a to close. While the pumps 2 I and 2Ia continue to remain in full delivery forward stroke position and to supply iluid into their respective cylinders 4 and 5, the actual pressing starts.

Assuming now that the press platen 8 starting from the position shown in Figure 3 encounters unequally distributed forces during the pressing stroke, which forces are shown in Figure 4 and represented by arrows of different length accord ing to their magnitude. As will be seen from Figure 4, the greatest force acts upon the right side of the platen 8, thereby deflecting the platen from its normal plane A-A. This deflection resuits in an increase in the distance between the lower side at the left end of the reference bar and the lower side at the left end of the platen 8.

It will be noted that the tilting movement of the platen cannot cause a tilting movement of the reference bar 95 since the latter has no positive connection thereto and is separated from the platen byfthe ball |22 which constitutes a universal link between the platen 8 on one hand and the reference bar 95 and the, plunger II8 on the other hand, which latter is guided in the stationary press head I. Y Due to the above mentioned increase in distance between the left ends of the reference bar 95 and the platen 8, also the distance between the bottom portion of the plunger 92 and the bottom of the cylinder 9| increases, with the result that the fluid pressure in the cylinder 9| decreases. Consequently, the spring |01 shifts the plunger 98 downwardly until it is again balanced by the pressure in the cylinder 9|.

It may be assumed that the plunger 98 has moved downwardly to such an extent that the cam member I| actuates the switch arm |02, thereby closing the normally open switch 19. Closure of this switch establishes a circuit comprising the main supply line 11, line 16, lines 18 and 80, contacts and 50, line 53, solenoid 55, line 56 and main supply line 51. As a result thereof the solenoid 55 is energized and since it is stationarily mounted in the casing 3| while the three arm lever 83 is held in its positionby the solenoid 8|, the cylinder 3| is shifted toward the right, thereby causing the servomotor valve rod 21 to move toward the left and thereby to reduce the delivery of the pump 2|. During this rightward movement of the cylinder 3| relative to the piston 35, the increasing space between the latter and the right end wall of the cylinder 3| is lled with air entering through the check valve 33. In this way the correcting device according to the invention tries to bring the platen back to its normal plane.

As soon as the cylinder 3|, due to the energization of the lsolenoid 55, is moved toward the right, the arn 48 connected to the cylinder 3| brings the lower end of the snap lever 45 into engagement with the latch 42 so that the contacts 50 and 5| are spaced from each other. This immediately breaks the energizing circuit for the solenoid 55 with the result that the spring 40 starts returning the cylinder 3| toward its left end position. However, this leftward movement of the cylinder 3| does not take place with the same speed as the previous rightward movement of the cylinder 3|, since the air entrapped between the piston 35 and the right end wall of the cylinder 3| can escape only through the choke valve 34. The rate of the leftward movement of the cylinder 3| is, therefore, determined by the adjustment of the choke valve 34.

Under normal conditions the above mentioned action of the correcting device will be sufficient to bring the platen practically into its normal plane. However, if for some reason the distance between the left ends of the platen 8 and the reference bar 95 should, instead of being decreased, have further increased, the corresponding increase between the bottom of the cylinder 9| and the bottom of the plunger 92 will allow the spring |01 to push the control plunger 90| downwardly to such an extent that the cam member |0| actuates the switch arm |04 pertaining to the switch |03 so as to close the normally open switch |03. This establishes a circuit comprising the main supply line 11, switch |03, line 54, solenoid 55, line 56 and main supply line 51.. The solenoid 55 is, therefore, energized and, in4 the manner previously described, causes the cylinder 3| to move toward the right, while the shifting member of the pump 2| places the latter on reduced stroke. However, it will be noted that in this instance the stroke of the cylindery 3| and, thereby, of the servomotor valve rod 21 is greater than in the previously described instance because the breaking of the contacts 5| and 50 after a portion of the stroke of cylinder 3| has no eiect on the energization of the solenoid 55. In other words, while in the above mentioned instance the energization of the solenoid 55 is interrupted, due to the breaking of the contacts 5| and 50 after the cylinder 3| has moved, by apredetermined distance but before it has reached the end of its rightward movement, the cylinder 3| now performs a complete rightward stroke. Consequently, the reduction in the supply of pressure fluid to the cylinder 4 is greater in the last mentioned instance than in the first mentioned instance. This reduction in the supply of fluid to the cylinder 4 will, for all normal, practical purposes, be sufcient to immediately start the leveling action of the platen, i. e., to bring the latter back to its normal plane.

As soon as, during this leveling action the distance between the bottom portion of the plunger 92 and the'bottom of the cylinder 9| decreases again, the increase in pressure inthe cylinder 9| acts upon the control plunger 98 and lifts the latter against the thrust of the spring |01. This upward movement of the control plunger 98 causes the cam member-|0| to release the switch arm |04 so that the switch |03 opens again. As a result thereof the energizing circuit for the solenoid 55 is interrupted and the spring 40 begins to return the cylinder 3| to its left end position and, consequently, to restore the pump 2| to its full delivery forward stroke position. As previously mentioned, the return movement of the cylinder 3| toward its left end position and, therefore, also the rate of the shifting movement of the pump 2| to its full delivery forward stroke position depends on the adjustment of the choke valve 34.

When the platen has reached the end of its pressing stroke, a mechanism is actuated either in response to the press platen or in response to a predetermined pressure in the cylinders 4 and 5 in a manner well known in the art, which mechanism then shifts the ow control or shift ring of the pumps 2| and 2Ia so as to place the said pumps into full delivery retraction stroke position. Pressure is then'delivered by the pumps 2| and 2Ia into the lower portion of the cylinders 4 and 5, respectively, through the conduits 20 and 20a, while the conduits 22 o and 22a become the suction lines.

After the release of pressure in the upper portion of the cylinders 4 and 5 by themain cylinder release and pump by-pass valves I9 and |9a at the initiation ofthe retraction stroke, the rams 6 and 1 begin to move upwardly. When the rams 6 and 1 have reached the end of .their retraction stroke, the platen arms and 90a engage the collars 89 and 89a on the push rods 88 and 88a, thereby causing the collars 81 and 81a on said push rods to shift the three-arm lever 83 in clockwise direction and the lever 83a into anti-clockwise direction so as respectively to move the pumps 2| and 2| a to neutral or no delivery position. The press Ithen comes to a standstill and is ready for a new cycle.

Supposing now that, during the pressing operation, an extraordinary situation is encountered. in which the above mentioned leveling action was not successful and that the distance between the left ends of the platen and reference bar had further increased with the result that the cam member I0| was moved downwardly to such .an extent that it engages the switch arm' |05.

This actuation of the switch arm |05 will then immediately open the normally closed switches 'I4 and 14a and, therefore, break the holding circuit for the solenoids 8| and 8|a. As a result thereof a spring'mot shown) in the servomotors 26 and 26a of the pumps 2| and 2Ia immediately reverse the ldelivery of the pumps 2| and 2Ia so that pressure uid is delivered from thesaid pumps into the lower portions of the cylinders 4 and 5 thereby returning the platen to its retracted or starting position, as previously described.

With regard to the embodiment shown in Figure 6, the operation thereof is the same as that 5 y described above so that a particular description of the operation of. Figure appears superuous. While the press described above has been shown with two pumps each of which pertains to one of the rams, it is of course understood that correcting device shown in the lower portions of Figures 2 and 6 Lwould actuate admission valves controlling the flow of fluid to the rams instead of the servomotor 26, a as previously described. Inother words, the electric control system actuated by the detecting and correcting 20 device of the invention could be used for actuat-4 ing an admission valve in the conduit 22, 22a respectively, while one single pump is adapted to supply pressure iluid through said admission valves into the cylinders 4 and 5 respectively.

It should furthermore be noted that while the correcting device shown in the drawings is provided with two correcting switches, namely, 19 and |03, it is of course possible and in many namely 03, in which instance the contacts 50 and 5|, the arm 48, the snap lever 45 and the latch 42 are superiiuous. I this instance the conduits 53 and 54 and the conduit 16 are, of

course, also superfluous. The device will then finement of the device inasmuch as it tends to nip any deflections of the platen from its normal position at the very point when it begins, while the switch l 03 allows a predetermined deection 'and then immediately starts to correctthe deflection of the platen. As previously brought out,

the actuation of the switch arm |02 pertaining to the switch 19 merely causes a partial stroke of the link cylinder 3|, while actuation of the switch arm |04 pertaining to the switch |03 causes a full stroke of the link cylinder 3|.

The correcting device according to the invention is very simple in structure and allows minute adjustment by actuation of the threaded plunger H5. To facilitate such adjustment, the cam member |0| is preferably provided with a mark |30 which, when properly adjusted, may register with a corresponding mark |3| in a window |32 of the cap.

While the detecting and .correcting device according to the invention has been illustrated and described so as to bring about the leveling operation or correction of the platen deiie'ction when the space between the adjacent ends of the platen and the reference bar increases, it is, of course, understood that the cam member |0| and switches 14, 19 and |03 may, if desired, be so arranged that the leveling action is brought about in response to a decrease in the distance between the adjacent ends of the reference bar and the platen.

It is of course also understood that instead of providing only two platen actuating rams as shown in the drawings, also a greater number. of platen actuating rams may be connected with the platen. Furthermore, the. rams may be connected with the platen at any convenient place although it is preferable `to mount one ram at each corner of the platen.`

It will be understood that I desire to comprehend within my invention such modiiications as come within the scope of the claims and the invention.

Having thus fully described my invention, what I claim as new and 2desire to secure by Letters Patent is:

1. In a press having a press platen, a plurality of iiuid operable means for advancing said platen, a iluid source for supplying pressure fluid to said iiuid operable means, and electrically operable control means responsive to a predetermined deflection of said platen for varying the supply of fluid to one of said iiuid operable means to reduce said deiiection.

2. In a press having a press platen, a plurality of uid operable advancing means for advancing said platen, a fluid source for supplying pressure fluid to said means, a reciprocable member arranged coaxially with said platen, and electric means operable by said member in response to deflections or tilting movements of said platen for controlling the relative speed of movement of said fluid operable means.

3. In a press having a hydraulically operable press platen, a press headja control member recases quite sufficient to provide only one switch, 30

ciprocably mounted in said head and responsive to the movement of 'said platen in vertical direction only, and electric means controlled by said control member in response to deilections or tilting movements of said platen for correcting said deflections or tilting movements.

4. In a press having a press platen, a plurality of identical cylinder-piston-assemblies operatively connected with said platen, a iiuid source for supplying pressure fluid to said cylinder-piston-assemblies, each of said cylinder-piston-assemblies having associated therewith identical fluid supply control means, reference means common to said control means and resting substantially on the center portion of said platen, guiding means for guiding said reference means in vertical direction while simultaneously preventing said reference means from following deiiections or tilting movements of said platen, and

* trol means to thereby vary the supply of iiuid to said cylinder-piston-assemblies to correct said deiiections or tilting movements.

5. In a press having a press platen, a plurality of double-acting fluid operable plungers for advancing and retracting said press platen, a uid source for supplying pressure fluid to said plungers, means for controlling the supply of pressure iluid to the advancing side of said plungers individually in response to a predetermineddeviation or tilting movement of the platen, and means for concomitantly reversing the flow' of iluid between said uid source and said plungers in response to a deviation or tilting movement of said platen in excess of said predetermined deviation or tilting movement.

6. In a press having a press platen, a plurality of independently operable iluid motors for reciprocating said platen, a plurality of independently operable control means associated respectively with said motors for controlling the speed thereof, and fluid operable plunger means responsive to deflections or tilting movements of said platen for actuating one of said control means to bring about a change in the speed of one motor Without changing the speed of another motor, thereby leveling said platen.

` 7. In a press having a press platen, a plurality of fluid operable cylinder-piston-assemblies for advancing said platen, a fluid source for supplying pressure fluid to said cylinder-piston-assemblies, electrically operable controlling means for `individually controlling the supply of fluid to said cylinder-piston-assemblies, and a plurality of control(l elements operatively connected with each of said controlling means and adapted responsive to predetermined different deviations or tilting movements of the platen to effect different controlling actions of said controlling means to correct said deviations or tilting movements.

8. In a press having a press platen, a plurality of fluid operable motors for actuating said platen, a fluid source for supplying pressure fluid to said motors, controlling means adapted individually to control the supply of fluid to said motors, electric means operable to cause actuation of said controlling means, and a reciprocable member 'movable in response to a deflection or tilting movement of said platen for actuating said electric means to bring about correction of said deflection or tilting movement. A-

9. In a press having a press platen, a plurality of fluid operable motors associated with said platen for actuating the same. a fluid source for supplying pressure nuid to said motors, controlling means for individually controlling the supply of fluid to said motors, a press head, a reciprocable member vertically movable in said head, and a plurality of control cylinders corresponding in number to said motors and each having reciprocably mounted therein a control plunger, each of said control plungers being connected to said reciprocable member and being adapted-in response to a deflection or tilting movement of said platen to cause adjustment of one of said controlling means.

10. In a press having a press platen, a plurality of fluid operable motors for actuating said platen, a fluid source for supplying pressure fluid to said motors, each of. said motors having associated therewith controlling means for individually controlling the supply of fluidv from said fluid source to said motors, a press head, a vertically reciprocable member mounted in said head and supported by said platen, means associated with said platen for allowing universal movement of the latter relative to said reciprocable member, and means operatively connected with said reciprocable member and responsive to deflections or tilting movements of said platen for actuating said controlling means.

11. In a press having a press platen, a plurality of fluid operable cylinder-piston-assemblies for actuating said platen, and a plurality oi reversible variable delivery pumps corresponding :in

number to the number of said cylinder-pistonassemblies and adapted to supply pressure fluid to the latter each of said pumps having associated therewith servomotor means, a plurality of control means respectively associated with said servomotor means and operable in response to a predetermined deflection or tilting movement of l the platen for actuating the respective servomotor means, each of said control means being operable to vary the delivery of one pump without causing a change in the delivery of another pump.

12. In a press having a press platen, a plurality of fluid operable cylinder-piston-assemblies for actuating said platen, fluid supply means hymined deflecting movement of said platen for` actuating said controlling means to vary the flow of fluid from said' supply means to at least one of saidcylinder-piston-assemblies tobring about a correction of said deilecting movement of said platen.

13. In a press having a press platen, a plurality of fluid operable .cylinder-piston-assemblies for actuating said platen, fluid supply means hydraulically connected with each of said cylindern piston-assemblies and having controlling means associated therewith for individually controlling the supply of fluid from said fluid supply means to said cylinder-piston-assemblies, a plurality of detecting devices corresponding in number to said cylinder-piston-assemblies and each comprising a plurality of switch means operatively connected with said controlling means, and a plunger adapted in response to different predetermined deflections or tilting movements of said platen to actuate different switch means for variably adjusting said controlling means to correct said deflections or tilting movements of said platen.

14. In a press having a press platen, a plurality of fluid operable cylinder-piston-assemblies for actuating said platen, fluid supply means hydraulically connected with each of said cylinderpiston-assemblies and having controlling means associated therewith for selectively, individually or collectively controlling the supply oi. fluid from said uid supply means to said cylinder-pistonassemblies, aplurality of detecting devices corresponding in number to said cylinder-pistonassemblies, each of said detecting devices comprising a plunger reciprocable in response to tilting movements of said platen, and a plurality of .actuating members operable by said plunger and operatively connected with said controlling means, one of said actuating members being adapted in response to a predetermined tilting movement of the platen to reduce the supply of fluid from said fluid supply means to the respective cylinderpiston-assembly, and another of said actuating membersbeing adapted-in response to a tilting movement of the platenin excess of said predetermined tilting movement to reverse the flow of fluid from said fluid supply means between all cylinder-piston-assemblies and the fluid supply means pertaining thereto to cause retraction of said platen.

15. In a press having a press platen, a plurality of fluid operable cylinder-piston-assemblies, each having associated therewith a reversible variable delivery pump for supplying pressure fluid to the respective cylinder-piston-assembly,V servomotor means associated with each of said pumps for controlling the supply of fluid from each pump to its respective cylinder-piston-assembly, each of said servomotor means having associated therewith a collapsible link operable selectively to be actuated in collapsible or non-collapsible position, starter means operatively connected with said collapsible links and adapted to start all pumps simultaneously, and a plurality of controlling members corresponding in number to said cylinder-piston-assemblies. each of said controlling members being operatively connected with one of said links and adapted to operate said link in response to a predetermined tilting movement of said platen for actuating the respective servomotor means.

16. In a press having a press platen, a plurality of cylinder-piston-assemblies operatively connected with said platen for reciprocating the same, a plurality of reversible variable delivery pumps corresponding in number to the number ot said cylinder-pistonassemblies, each of said pumps having associated therewith a servomotor with a collapsible link for controlling the supply of fluid from the respective pump to the cylinderpiston-assembly pertaining thereto, said collapsible link comprising two elements movable relative to each other, one of said elements being connected with said servomotor and carrying a solenoid, and the other movable element being connected with a link system operable by starter means, yielding means interposed between said two movable elements, and a plurality of detecting devices corresponding in number to said cylinder-piston-assemblies and being adapted in response to a predetermined tilting movement of said platen to energize one of said solenolds.

17. In a press having a press platen, fluid operable means for advancing said platen, uid supply means for supplying pressure fluid to said fluid operable means, control means associated with said uid supply means and comprising collapsible link means for controlling said control means, and detecting and correcting means responsive to predetermined tilting movements of said platen and operatively connected with said collapsible link means for variably expanding said collapsible link means ln response to diilerent predetermined tilting movements of said platen to correct said tilting movements.

18. In a press having a press platen, a plurality of fluid operable plungers for advancing said platen, a plurality of control elements independent of each other and respectively associated with said plungers for controlling the supply of iluid thereto, and means responsive to a predetermined deviation of one end of said platen in one or the other direction for actuating only one of said control elements to vary the supply of fluid to one of the plungers without charging the supply of fluid to another plunger.

PAUL E. FLOWERS.

CERTIFICATE OF CORRECTION.

Patent No. 2,509,94l1.. February 2, 19kg).

PAUL E. FLOWERS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring -correction as follows: Page 7, second column, line 25, for charging read --changing; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the cese in the Patent Office.

Signed and sealed this 6th day of April, A. D. 19115.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

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