US2353388A - Apparatus for controlling the slide movement in long-bed hydraulic presses - Google Patents

Apparatus for controlling the slide movement in long-bed hydraulic presses Download PDF

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US2353388A
US2353388A US463604A US46360442A US2353388A US 2353388 A US2353388 A US 2353388A US 463604 A US463604 A US 463604A US 46360442 A US46360442 A US 46360442A US 2353388 A US2353388 A US 2353388A
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slide
press
chambers
liquid
movement
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Cannon Earl
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EW Bliss Co Inc
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EW Bliss Co Inc
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B30PRESSES
    • B30BPRESSES IN GENERAL
    • B30B15/00Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16Control arrangements for fluid-driven presses
    • B30B15/24Control arrangements for fluid-driven presses controlling the movement of a plurality of actuating members to maintain parallel movement of the platen or press beam

Description

CANNON APPARATUS FOR CONTROLLING THE SLIDE MOVEMENT IN LONG-BED HYDRAULIC PRESSES 4 Sheets-Sheet l lfiled Oct. 28. 1942 a w V TORNEYS INVENTOR -fl924 C/Y/vWOA/ Jufiy H, w. E. CANNON APPARATUS FOR CONTROLLING THE SLIDE MOVEMENT IN LONG-:BED HYDRAULIC PRESSES Filed Oct. 28, 1942 4 Sheets-Sheet 2 APPARATUS FOR CONTROLLING? THE SLIDE MOVEMENT IN LONG-BED HYDRAULIC PRESSES Filed 001;. 2 8 1942 4 Sheets-Sheet 5T July 111%., 1944. E, CANNON? 2,353,388-

BY M ATTORNEYS July 11, 1944. E. CANNON APPARATUS FOR CONTROLLING THE SLIDE MOVEMENT IN LONG-BED HYDRAUL IC PRESSES Filedpct. 28, 19 42 4 Sheets-Sheet 4 INVENTOR 5w?! ('fi/VNoM- ATTORN EYS Patented July 11, 1944 PBESSES IN LONG-BED HYDRAULIC Earl Cannon, Rockville Centre, N. Y., asslgnor to E. W. Bliss Company, Brooklyn, N. Y., a corporation of Delaware 20 Claims.

This invention relates to improvements in apparatus for controlling the slide movement in long-bed hydraulic presses, and more particularly relates to improved means for maintaining the slide of such a press substantially in parallelism with the press bed during the advance or downward movement of said slide despite any die or blank irregularity which might tend to induce tilting of the slide.

Any reference in the following specification and claims to parallelism or non-parallelism Application October 28, 1942, Serial No. 463,604

is intended to relate to the attitude of the press .slide relatively to' the bed of a press.

An important object of the present invention is the provision of improved means for auto matically effecting variations in the flow of liquid to plural rams at various points. along a press slide whereby to. substantially compensate for initial inequalities in such flow caused by unequal resistance oflered to the advance of the press slide at various: points thereon. The foregoing and other objects and advantages of the invention will be apparent from the following specification and from the accompanying drawings.

The invention disclosed herein constitutes improved means of achieving the above objects and are necessary to-an understanding of the improvements illustrated and claimed herein.

The means disclosed in said co-pending application are chiefly mechanical means which are employed to eilect compensatory transfer of liquid from a liquid supply for a ram or rams toward one end of the press slide to a liquid supply for a ram or rams toward the opposite 'end of the slide. The improvements of the present invention, however, are directed toward the accomplishment of said objects through electrical or pneumatic apparatus and circuits which are employed to achieve a response to non-parallelism and to control such a compensatory trans- I fer of liquid.

For the purpose of illustrating the present invention, and without limiting the invention thereto,iseveral embodiments thereof are shown in the accompanying drawings,-in which:

Figure 1 is a perspective view of certain important parts of a preferred embodiment-oi the present invention (hereinafter referred to as the first embodiment), and of a long-bedpress on which it may be employed. V

Fig. 2 is a detailed view, in end elevation, showing means employed for initiating a response to nonparallelism and for controlling certain compensating means employed as a part of the present invention.

Fig. 3 is a diagram illustrating the intercon nection of parts comprising the said first embodiment of the invention.

Fig. 4 is a side elevation of a variable iulcrum lever which may be employed advantageously-in the present invention.

4A is a sectional view on the line X-X of Fig. 4.

Fig. 5 is a diagram illustrating the interconnection of parts comprising a second embodiment of the invention.

r the objects set forth in my co-pending applica- Referring first to the disclosures of Figs. 1-3, the press with which the first embodiment is illustrated may comprise a. long-bed H provided in a base. I! suitably tied at its opposite ends to a crown I3 by tie rods l4 extending through slide housings l5 which serve at least partially to guide a vertically reciprocating slide it and to suitably space apart the saidcrown and bed and maintain the two latter members fixedly in their ,proper relationship. Tie rod nuts l'l prefer ably are provided at the upper' and lower ends (the latter are not visible in the drawing) of the said tie rods.

The slide it is reciprocated in a well-understood manner, by rams 181:. and l8b, fixed symmetrically upon the slide, toward opposite ends thereof. These rams, as best understood from Fig. 3, may-be enlarged at their upper ends to form 'ram pistons I So, Nb and may be'urged downwardly on their advance strokes by liquid introduced into advance chambers 20a, 20b and upwardly on their return strokes by liquid introduced into return chambers 2la, 2). The said chambers, of the general character indicated in Fig. 3, may, of course, be suitably formed 1 within the crown is of the press.

Separate, substantially identical pumping sys- 23 through pipe 24a and pumps said liquid through pipe 25a into a distributing slide valve 2 .e,sss,sss h v are connected in suitable electric circuits for con- 26a. which, depending upon the position of a piston 21a. therewithin, directs the liquid either through a pipe 28a to the ram. advance chamber 20a to move the ram lBa. downwardly or through a pipe 29a to the ram return chamber Zia to move the said ram upwardly, or, through a pipe 3.0a, backto the tank23, when it is desired that the ram remain substantially at rest. .The mentioned liquid distribution, yielding the said ram Q movements, is controlled largely by the provision on the pistoni'la. of three enlarged portions or spools am, 32a and 33a and intervening neck portions 34a and 36a.

When it is desired to advance the ram l8a (i.-e., move it downwardly) to advance the slide l5 l6 toward the bed I I and a die and blank thereon, the piston 21a is shifted, by any suitable means,

to its extreme left position as shown in Fig. 3, f

whereupon liquid entering the valve 26a, through pipe 251:, passes around neck portion 34a, of the said piston, into pipe 28a, and thence to the ram advance chamber 20a, thereby forcing the ram lfla downwardly while liquid is exhausted fr the ram return chamber 2ia through pipe 23 into the valve 28a, wherein the exhaust liquid passes around neck a of said piston to pipe 3011 which carries it to the tank 23. By shifting the piston "21a, to its extreme right position, the

flow of liquid is reversed with respect to the said 1 ram chambers thereby causing the ram -l8a to so pursue its upward or return movement.

when it .is desired to arrest the movement of the ram l8a, the piston 2111, may be moved to its mid-position, in which the several. mentioned spools on said piston close ofi all liquid commu- 3 nication between the pump 22a and the ram chambers 20a and 2la. However, the liquid, continuing to be discharged by the pump 22a passes "from pipe 25a into interior lateral passage 35a in the spool 32a, thence through longitudinal passage 81a into lateral passages 38a, 39a in the spools 3 la and 33a, whence said liquid passes into pipe 301; which carries it to the tank 23.

In view of the similarity of the pumping systems for actuating the two rams, the foregoing. description is intended to sufice for both. For

this reason, the similarparts of the pumping systems are given reference characters, in the drawmas and hereinafter in the specification, difiering only in their su'mxes, the sufllx a being applied to parts of the pumping system related to ram I80 and the sufllx I) being applied to parts of the pumping system related to ram lab. Both valves 28a and 28b function alike and-may be As illustrated in theaccompanyin drawings, 65

an electric solenoid may suitably be connected as by a pin I to an end extension M of the piston 21a. The said solenoid is adapted, when energized, to move the pistons 21a and 21b to their left positions, as shown in the drawings, to cause. downward movement of the press slide l8. An-

other solenoid 45 may be similarly connected to the piston 21b for moving both pistons tothelr right positions to cause upward movement of the press slide. The-two said solenoids, of course, my

trolling the operation of the press.

The pistons 21a, 2'") may be held yieldably in their mid-positions by any suitable means which, for example, may employ springs or air or hydraulic pressure. As illustrated in the accompanying drawings, a spring centering device is employed comprising a coil' spring 45 which is positioned about the extension rod 40b and iscompressed between washers 41 which, normally,

are held against the end of said spring by collars 48 formed on or fixed on the rod 40b. A cagelike frame 49 is fixed upon some fixed part of the press or other suitable fixed support in such position, adjacent the rod "b,- that the latter passes through holes 50 in the ends of said frame,

largeenough to freely pass the said collars but smallenough to confine the washers 41 within the said frame. Thus, when the pistons 21a and 21b are held in their left positions, as illustrated in the drawings. by the energised solenoid 42, I

the spring 46 is exerting compression uponthe right washer l1 and the right collar 48 which, when the said solenoidis de-energized, will cause the said pistons to move to their mid-positions. A similar, but opposite action of the centering device results when the said pistons are held in their right position by the solenoid 45 and the latter isthen de-energized.

Although the pumping systems f r operating the rains I81: and lab, as thus far escribed in detail, may be substantially identical in designflit will be appreciated that, where resistance to the advance of the slide is not uniformly distributed 5 thereover, the different slippages in the two pumps, slightleakages, and possibly other factors, would cause the side or end of the press slide encountering the least resistance to advance ahead of the other side thereof and this uneven advance or cocking of the slide, in many instances,

would become more pronounced as the slide pro- 1 s'ressed toward the end of its advance stroke.

This highly undesirable functioning of the press maybe substantially obviated by compensating means now to be described in detail.

An important feature of this invention is the provision of automatic and quickly responsive means for substantially equalizing the supply of liquid to the hydraulic chambers of the several rams which actuate the press slide. According to the first embodiment of the invention it is preferred to provide suchmeans comprising a compensator pump 5| (Fig. 3) connected by a pipe 52 to the pipe 28a which carries the liquid supply to ram advance chamber 20a, and connected by a pipe 53 to the pipe 28!) which carries the liquid supply to ram advance chamber 20b.

The compensator pump 5| may bea continuously acting reversible pump, suitably driven as by an electric motor (not shown) The said compensator pump further is preferably providedwith a pumping mechanism, which is movably adjustable'by means which extend to the exterior of the pump itselifiior reversing the fiow of liquid through the pump and for controlling the volume of such flow. Although various types of pumps, having pumping mechanisms conforming to these preferred characteristics, may be used, a pump of the so-called "Hole-Shaw type such as is illustrated and described in my said co-pending patent is well suited to the purposes of the invention.

As the particular control mechanism employed in the compensator pump is not an essential part of the present invention, the saidpump is not and drain chambers 661 and 661.

herein describedin detail. It is sufficient to observe for present purposes that the flow of liquid through the pump may be reversed and the volume thereof controlled by a reciprocating control member 54 which extends from the interior mechanism of said pump to the exterior'thereof and the air motor- 58. r The valve 58' may be provided with a centering spring 18 which operates to center the piston '18 in the same manner as and is operatively connected through a lever 55 I to an extension 56 of a piston 5I,of an air motor 58. The said motor, as hereinafter explained, is automatically operated in such manner as to regulate the direction and volume of flow of' liquid through the compensator pump ii in order to derive a transfer of a suitable volume of liquid from the liquid supply'of one of the mentioned rams to the liquid supply of the other of said rams whereby to substantially restore and maintain parallelism of the press slide during its advance movement.

The supply of air, as 'a driving medium, to the air motor 58,-is preferably controlled by means of an air distributing valve 59 and an air release valve 68. In carrying out the present invention it is preferable to provide electrical means for operating the valves 58 and 68, which electrical means may conveniently be arranged to respond to non-parallelism of the press slide and to control the operation of the air motor 58 so that the latter may operate the control means of the pump 5| to give to the latter its desired compensating effect.

The piston 51 of the air motor 58 has two spools or piston heads 6 and Mr integrally formed therewith or fixedly secured thereupon and is arranged to reciprocate within a borei'n an elongated casing 62. The said bore is of different diameters at various points therealong to form a central, air chamber 68 and certain oppositely-acting air chambers located toward opposite ends of said casing, namely, balancing chambers 641 and 841', driving chambers 851, 651',

All the mentioned chambers in the air motor 58, as shown in Fig. 3, are provided with suitable ports which, in the case of the drain chambers 66!, 661' afford communication between said chambers and .1e free exterior air, and in the cases of the other I is movable toward the left against the compres-' mentioned chambers afford means of connecta ing the latter to a compressed air lineand to the air valves 58 and. 88.

Similar oppositely-acting centering sleeves 8'11,

the piston 51 at points between the spools 811 and H1. These sleeves have similar annular flanges 68f on their inner ends, the said flanges being arranged to work within the central air chamber 63.

The air distributing valve 59 is very similar to the hydraulic distributing valves 26a and 26b. It comprises a piston '18, having three spools H, 12, '18 formed on or fixed thereon, and accurately fitted to slide within a bore 14 in a casing 15. The said spools define neck portions 1 l6 and 11 on said piston. The valve 58, as shown in Fig. 3, is provided with suitable ports, which may be covered and uncovered by the spools II, l2, 18, when the piston I8 is moved to various the spring 46 functions to center the pistons'of the hydraulic valves 28a and 26b. The piston I8 is connected to oppositely-acting solenoids l8, 7

tween. The casing 85, as shown in Fig. 3, is

provided with several ports affording means for connecting th interior of the bore 84 to free air and to pipes leading to the air motor 58 and the valve 58. The piston is'normally urged toward the right by a compression spring 86 and sion of said spring by means of a solenoid 81 which is suitably connected to said piston. Thesaid solenoid is connected in electric circuits,

hereinafter described.

In order to mechanically detect any non-parallelism of the press slide 16, a pair of vertically disposed racks 88 (see Fig. 1) are secured at their lower ends to the slide I6 toward opposite ends thereof. The said racks may be guided within suitable guides 88 fixed upon the crown l3, and when the Slide descends, the racks rotate shafts 981 and 88 in common directions through the medium of step-up gears 8|, which are suitablyjournaled upon brackets 82. The gears 8| It will readily be understood that if the slide It remains in parallelism with the press bed ll shafts 881, 981' to rotate to a greater degree than v the other of said shafts.

Although the mentioned difference in the degrees of rotation of the shafts 881, 881 may not,

be very great, means are provided in the present invention whereby such difference in rotation causes the closing of an electric circuit or circuits which control the operation of the air valves 58 and 68 which, by controlling the flow of air to the air motor 58, cause the latter to operate the control means of the compensator pump 5i whereby to substantially equalize the supply of liquid to the hydraulic chambers ofthe several rams which actuate the press slide.

The mentioned means for closing said circuits, as may best be understood from Figs. 1 and 2, comprise a switch plate fixed upon th inner .end of the shaft 881' and constrained to turn therewith, and a plurality of electric switches 881 and 861', 8'11 and 811', and 881 and 981, arranged upon the switch plat '85 adjacent the periphery of a switch actuator 88 which is fixed upon the inner end of the shaft 881 and constrained to rotate therewith.

The several mentioned switches may be carried upon blocks I which may advantageously be slidalole, but with a. very close and tight fit, within slideways IOI. Means are provided for adjusting the positions of said blocks and switches relatively to the actuator 99, comprising lugs I02 through which are threaded adjusting screws I08 which bear against the outer sides of the the switches 0', 911 may be positioned with their operating plungers slightly spaced from the actuator 99 so that said switches may close in response to a relative movement slightly greater than that which closes switches 901, 061'; and switches 981, 981' may be positioned so that their operating plungers are slightly more removed from the actuator 90 than plungers of the switches 91!, 911'.

All the switches referrred to are of the type which hav become known as micro-switches" and are so designed that an inward movementof I their operating plungers of as little as .001 inch suflices to close a circuit through the switch, and further, are so designed that the switch plunger,

after moving inwardly sufliciently to close the circuit through the switch, is capable of inward non-effective overtravel. By utilizing switches of the mentioned character in the manner-described it .is possible to provide that the switches 901, 90r may be operated to close circuits therethrough while the operating plungers of the'other mentioned switches are moving within their men-t tioned overtravel. Similarly, switch 9'71 may operate within the overtravel of switch 981 and switch 911 may operate within the overtravel of switch 961.

Means are provided, in the form of a take-ofi drum I05 fixed upon the shaft 901', for connecting the several mentioned switches in suitable electric circuits. As seen from the elevational showingof said drum in Fig. 3, it comprises a plurality of take-oil rings I06, I01, I08, we, H0 and III, all insulated from each other and suitably connected interiorly of said drum to the several switches by wiring which is diagrammatically indicated in Fig. 3. The several mentioned take-.ofl rings are each engaged by wiper contacts which are preferably mounted upon the crown it of the press, and, from said contacts, connecting wires extend tocertain electric solenoids in a manner which is hereinafter described inconnection with the operation of the apparatus.

I The racks 80 preferably are split longitudinallyas indicated at 8811, and the two parts of each rack are, capable of relative longitudinal adjustment through the medium of suitable adjusting screws I2 carried by brackets H8 fixed upon the slide I0. By suitable adjustment of the screws I12, the parts of the racks 80 may be shifted slightly longitudinally relatively to each other whereby to eliminate all material lost motion between the'teeth of said racks and the teeth of the step-up gears 9i In practice, the parts of the described apparatus are so assembled that, when the slide I6 and the bed I I are perfectly parallel, the switches assasss I on the switch plate as and the actuator as are in the relative positions shown in Fig. 2. In such positions, normally open switches 981, 081', I'll and 011' are open, and normally closed switches 001 and 081' are closed and the pistons of the al valves 50 and 00 and of the air motor 58 ar all in the positions indicated in Fig. 3 of the drawinES.

'If the press is open and itis desired to cause the press slide I8 to move downwardly to perform a pressing operation, the operator sets switch Ill to its "down position, as shown mm. 3; thereby closing a circuit from main lead III (indicated as a negative lead), through switch III, wire III; the coil of solenoid, main lead 1, take-oil ring I00, thence by wire I I8 to and through series connected, normally closed switches 081-, 00! which are connected by wire H0 to take-oil rin I01 and thence to lead I20 which is indicated as a positive lead. Automatic or semi-automatic means may be and usually are'provided for controlling the circuits through solenoids and 45,

but such means are not described herein as they constitute no part of the present invention.

Upon the closing of the mentioned circuit through solenoid 02, the latter is energized and draws the pistons of the hydraulic valves 2011,2612 to their left positions as shown in Fig. 3, whereupon liquid from the pumps 22a, 22b passes through the valves 26a, 26b and pipe lines 28a, 20b toram advance chambers 20a, 20b, respectively, thus causing rams lac-and I8b to descend with the slide IS, the liquid from return chambers Ma, 2"), meanwhile, being exhausted through pipes 20a, 20b to the valves 26a, 26b and thence through pipes 30a, 30b back to the tank 28.

For present purposes'it may be supposed that the press contains a die or dies of such irregular vertical dimensions, or that the blank is of such a character, that the slide It, in its downward movement, meets a greater resistance to, such movement toward its right end, thus inducing, in the pump 22b, a greater slippage than is present in the pump 220., with the result that the latterv pump passes'a somewhat greater volume of liquid the result that the left side of the slide I6 tends to move downwardly ahead of the right side there- 0!, thus giving the slide an objectionable tilting attitude which may impair the precision of the pressing operation as aflecting the blank and which, in any event, introduces very objections] friction and consequent wear in the slide guides of-the'press.

However, immediately upon the -inception of such uneven descent and before the tilting of the press slide becomes objectionable in any practical sense, the shaft 90! rotates somewhat ahead of the shaft 901', thus imparting to the switch actuator 00 a clockwise motion (as viewed in Piss. l

' and 2) relatively to the switch plate 95, causing the said switch actuator to depress the plunger of thereby close a circuit from main lead Iii,

, through wire IZI, take-oil! ring III, wires I22, I23,

switch 1', wire I20, take-oil ring I00, wire III,

the coil of solenoid and wire I20, to main lead I I1. Upon the closing of the said circuit throuflh solenoid 00, the latter is energized and draws the piston of air distributing valve 50 toward the right against the tension of spring I0 to a position in which compressed air from air line I21 may freely enter the valve 69 through pipe III and pass along and around neck portion" ot the Piston ll,

whence it may pass out of the valve 59 through pipe I29 into driving chamber 651 of the air motor 58. I

As will'be seen from Fig. 3, the balancing chamhers-Bil, 641' are directly connected to air line I21,

hence the air pressure in said balancing chambers functions normally to maintain the piston 51 of the air motor in its mid position, as shown in the drawings, by air pressure exerted on the outer ends of the sleeves 811, 911', which press at their inner ends against the spools ill, 6 Ir, respectively. However, when compressed air at the same pres sure is introduced into driving chamber 651, in

greater than the difference between the forces of the pressure on the left and right sides of the flange 81) of the sleeve 611, hence the piston 91 is driven toward the right until the spool Gil engages the left end of the sleeve 691 but proceeds nofurther inasmuch as the force of the air pressure within the central air chamber 63, which is normally connected to air line I21 through pipe I30 and valve 60 exerts a greater force upon sleeve 69! than the difi'erence in the forces applied to the spool Bil in the chamber 651 and to the sleeve 1 611' in the chamber 991'. p

The mentioned limited shifting of the piston 51 to the right in the manner just explained causes the lever 55 to turn about its fulcrum 55a and move the control member 54 of the reciprocating pump 5| to the left, andthe'connection of the said control member to the said pump is such that larity of the die or blank causes the left side of the pressslide l6 again to move ahead ofthe right side thereof, the. described apparatus again functions in a similar manner to bring the compensator pump into play to again restore the parallelism of the press slide. This compensating action may conceivably take-place a number of times during the advance of the press slide so the manner just described, the force of said pressure exerted upon the left side of the spool Gil is that, during said advance, the press slide pursues an almost imperceptible rocking action. The latter action, of course, is restrained within permissibl limits so that, inso' far as any material considerations are'concerned, the press slide is maintained in parallelism with the bed of the press during its entire advance movement;

It should be understood, of course, that if the irregularity of the die or blank is such as to cause the right side of the press slide Hi to advan'ce slightly ahead of the left side thereof the apparatus already described eflects compensation in the manner just explained, except, of course, that the switch actuator 99 operates switch 961 instead of'switch9l5r, and, as the former switch is, connected through take-off ring "B8 to the coil of solenoid 19, the piston of the air distributing valve 59 is moved to the left instead of to the right. so that compressed air is introduced into chamber fiirotthe air motor 58 instead of into chamber 69! thereof, thereby causing the piston of said air motor to move toward the left, thus causing the reciprocating control member 59 of the compensating pump to move the latter pumps liquid through pipes 53 and 52 i from the primary liquid supply of .ram l8a to the primary liquid supply of ram l8b.

This pumping action of the pump 5|, resulting from the limited shifting of the piston 51 of the air motor 59 and the consequent limited control change in the compensator pump 5|, may transfer suflicient liquid from one side of the press to the other to fully compensate for the pre-existing inequalities in the volumes of liquid supplied to the opposite side of the press, with theresult that the slide l9 of the press is restored to parallelism with the press bed ll. While such restorat on is taking place, there occurs a counterclockwise movement of the switch actuator 99 relatively to the switch plate which permits switch 961' to open, thus breaking the mentioned circuit through solenoid 99, whereupon the piston 10 of the air distribut ng valve 59 is restored to the mid position shown in Fig. 3 by the centering spring In the'said midposition of piston II, the spool 12 closes oif pipe 129 while driving chamber 6510! the air motor is connected to exhaust port 39 of air valve 59 through air pipe I29 and through the said exhaust port I99 and pass through the latter interior of valve 59 wherein the exhaust air from chamber 691 may pass around neck portion 19 to to free Upon chamber ii! of-the air motor,

being connected to free air in the manner just' described, theair pressure in the balancing cham her 94; functions to move sleeve Sir-to the left, carrying the piston 91 with it back to-the latters midposition, as shown in the drawings. Thesaid movement of the mentioned piston; of course, restores the control member 99 of the compensator pump 5| to its normal position in which the pumping mechanism of said pump, although being driven by its motor, is nevertheless not passing any liquid.

If, after the discontinuance of the pumping action of the compensatorpump ii, the irreguto the right whereby to cause the pumping mechanism of said pump to transfer liquid from the primary liquid supply of ram 18b to the primary liquid supply of ram 18a, thus'restoring the par-' allelism of the press slide.

It may occur'in practice that dieor blank irregularities or other conditions may be such as to cause a more pronoimced or objectionable tilting of the press slide than the permissible tilting which the compensating means thus far described is adapted to compensate. Such objectionable tilting may be of such magnitude that, ifwe 25- sume the left side of the press slide to be moving in advance of the right side thereof, not only would switch 9ST be'closed bythe actuator 99,, but the clockwise rotation of said actuator relatively to switchplate would be sumcient to also close switch 9'" which, as may be seen from Fig. 3, is connected through take-of! ring! with the coil of solenoid 91. Thus, in the event of such excessive tilting of the press slide, the, solenoid 81 is energized and moves piston M- of air release valve ill toward the left against the compression of spring 89, causing spool 89 to close off airline I21 from communication with the interior of said valve and at the same time affording a passage permitting air from central air chamber 63 of the air motor 98 to exhaust through pipe I99 into release valve 99, whence said exhaust air'passes aroimd and along the neck portion of the piston 9l and escapes to free air throughexhaustport I98. 9

Upon the opening of central, air chamber 69 of the air motor I9 to exhaust, the sleeve 99! ther movement of the reciprocating control meme ber 54, of the compensator pump, toward the left, thus increasing the compensating flow of liquid through the pump to yield suflicient additional compensation to overcome the excessive tilting of the press slide and restore it to parallelism;

. in the event that excessive tilting of th press slide occurs in which the right side of the press side thereof, the switch actuator 99 closes switch 31! instead of switch 911. It will beobserved, however, that both mentioned switches are connected in circuit through the coil of solenoid 81,

"thus, regardless of which side of the press slide slide moves downwardly in advance of the left movements it is preferable to provide a variable fulcrum point for the lever I55.-

Preferred means of providing a variable fulcrum point forthe lever 55 are illustrated in.

Figs. 4 and 40. As illustrated, the lever 55 is formed of two opposed similar side pieces I32o,

I321! which are spaced apart,,and the upper ends thereof are pivotally connected to opposite sides of the outer end of the reciprocating control member 54. The lower ends of said side pieces are pivotally connected at opposite sides of one end of a link I33 which is connected to the extension 56 of the piston of the air motor 58.

-A bracket I33 is fixed, as by machine screws or bolts I34, upon any convenient fixed surface of the press installation located sufliciently near to the compensator pump 5| and the air motor 58 that an elongated extension I35 of said bracket may extend between the side pieces I320: and I32b. Over substantial portions of their lengths thesaid side pieces are slotted as at I36, and

piston to move beyond its initial limited movement; causing a corresponding increase in the movement of the reciprocating control member 54 of the compensator pump to the right so that the flow of liquid through said pump, in the proper direction, is increased sufficiently to yield the desired increased compensating effect.

- Under some conditions it may b feasible to dispense with .the air release valve 60. If this is done, the apparatus employed would be so,

adjusted that the compensator pump 5I, under any anticipated operating conditions, would fully yield the compensating effect necessary to re store the parallelism of the press'slide as a result of a single shift of the control member 54. However, if the compensating capacity of the compensator pump 5I is stepped up sufficiently to cause adequate compensation, in all instances,

in response to the closing of only a single switch, 361 or 861, compensation would occur very rapidly the extension I35 is slotted as at I3'I. A follower block I38 is threaded upon and movable longitudinally within the slot I31 by an elongated screw I38, an unthreaded portion at the lower end of which seats within a. socket I88 at the lower end of the slot I31. The screw I39 is threaded over all of its length exceptthe lower end portion just mentioned, and the upper end I4I which may be of any suitable shape for receiving a wrench to turn said screw or may, if desired, have a small hand wheel fixed thereto. The upper end of the extension I35 serves as a lug I42 through which the screw I39 extends, and lock nuts I43 are provided on said screw at each side of said lug to permit locking the said screw in position.

The follower block I38, as best seen-in Fig. 4a,

' the lever 55. The said trunnions each fit accuand consequently the mentioned rocking of the press slide, under some circumstances, might be objectionably rapid, and during a single advance stroke of the slide might occur so frequently as to be objectionable.

rately into bores of blocks I45 whichare suitably formed to slide within rabbets I48 formed along the inner sides of the slots I36. It will be observed from Fig. 4a that, except fo the trunnions I, the follower block I38 is the same width as the adjacent portions of the extension I 35 and that the inner surfaces of the blocks The air release valve is advantageous in that,-by its'use, a complete stroke of the piston 6'I'of the air motor- 58 and consequent extreme adjustment of the control member 54 of the compensator pump, is accomplished in two distinct steps rather than in one step. If excessive tilting of the press slide occurs, the mentioned' two step adjustments yield the maxi- I mum compensating effect necessary to restore the press slide to parallelism. However, the tilting of the press slide, in many cases, may be compensated before becoming excessive, bythe effect of only one step of compensator pump adjustment. It follows that when only the lower compensating effect, of a single step of compensatorpump adjustment, is brought into play, the rocking action ofthe press slide is much slower and not frequent enough to be objectionable.

It may be understood from the foregoing explanation of the effects of too rapid compensation, that it is important to so correlate the movement of the piston 51 of the air motor 58 to the movement'of the reciprocating control element 54 of the compensating pump that only the proper degree of compensation is obtained. In order to readily permit correlation of t e e I45 arein the same plane as the inner surfaces of the side pieces I32a, I 32b. Under this arrangement the said side pieces and the blocks I45 which slide therein are free to oscillate as a part of and with the lever 55 while the follower block I38, although capable of sliding motion within the slot I3'Iin response toturning of the screw I39, is nevertheless restrained against any oscillating movement. It will be seen that by means of the structure illustrated in Figs. 4 and 4a the fulcrum point 55a of the lever 55 may conveniently, be moved up or down, within all desired practicable limits, with respect to the lever 55 so that the action of the air motor 58 may be correlated to the action of the compensator pump 5|.

The second embodiment is illustrated in Fig. 5 and parts therein, which are similar to those illustrated in Fig. 3, are given reference characters which are similar except that where in Fig. 3 the suffixes a and b havebeen'employed in the reference characters of parts in the hydraulic systems supplying the two rams, suilixes a, b, c and d are employed in Fig. 5 in the referencecharacters of certain parts of the hydraulic systems supplying the four rams illustrated.

'I'he second embodiment may best be undermovements to the latter.

hydraulic distributing valve 26a handle the pri- .mary supply of liquidtoram l8a; the pump 22!) ate rams I81; and I.

instrumentalities employed in the first embodiment, to a long-bed hydraulic press in which four rams l8a, l8b, I80 and l8d are associated with the press slide IE to impart the desired pressing The pump 22a and and the hydraulic distributing valve 26b handle the supply of liquid to the ram 18b; a pump 22c and a hydraulic distributing valve 260 handle the supply of liquid to the ram I80; and a pump 22d and a hydraulic valve 26d handle the supply of liquid to the ram I811.

V Instead of employing only a single compensator pump, it is preferred, in the second embodiment,

, to employ two substantially similar compensator pumps I be and 5 lad, the former being connected by suitable pipes 52b0, 5317c, between the pipes 28b and 280 which carry liquid to the advance chambers which actuate rams l8?) and l8c, and the latter pump being connectedby suitable pipes 52 530d, between the pipes 280 and 28d which carry liquid to the advance chambers which actu- The single air motor is is adapted to actuate the reciprocating control members 5lbc and 54nd of the two compensator pumps by connecting the "ating each of the hydraulic distributing valves. However, as it is necessary that the said valves function similarly and simultaneously. the sole- .noids 42a, 42b, 42c and 52d which function to shift the pistons of their related hydraulic dispensator pumps controlled so as to give efiect to the said diilerences in the volume of liquid transfer as between the two mentioned pairs of rams. This may easily be accomplished by varyingthe position of the fulcrum of each'of the levers 55b0, 55nd, so that for any given stroke of the piston 51 of the air motor 58 the resulting stroke of the control member 5411c will be substantially less than the resulting stroke of the control member 54nd so that the rate of flow of liquid through the pump ilad will be substantially greater than the rate of flow through pump 5lbc. Itwill be seen that proper adjustment of the fulcrum points of the two mentioned levers will yield a proper rateof flow through the two compensator pumps. In the event that the slide IS, in its downward movement, is tilting to one side or the other, one or more of the several electric switches, in the manner already fully described, will close and causethe air motor to bring the pumps Slim and ilad into play to cause transfer of compensating I liquid between the liquid supplies to rams I8b and I80, and between the liquid supplies to rams "a. and l8d.

It will be observed that in both modifications the switches 98], 98r are connected in series through the take-off rings I06, I01 between the wire I20 and the main lead I". These switches are normally closed so that in normal operation the circuit between said wire and lead is closed.

, The said switches 98l and 381', as best seen from Fig. 2, may only be actuated by the actuator 99, by rotation of the latter relatively to the switch plate 95 to a. greater extent than is necessary to actuate switches 911 and 911.

Ordinarily, compensation takes place in all cases before actuation of the switches 981 and trlbuting valves to the left, are all connected in parallel in a single circuit and the solenoids a, 45b, I and lid'which function to shift the pistons of said valves to the right are likewise connested in parallel in another single circuit. The first mentioned circuit which causes the mentioned left shifting resulting in a downward movement of the press slide I6, is closed when the switch I u is'set to its down" position, and

I the second mentioned circuit which causes the mentioned right shifting resulting in an upward movement of the press slide I6 is closed when the switch {II is set toits p position.

Inasmuch as the hydraulic distributing valves,

28a, Ilb, 18c, lid in the second embodiment are all operated independently, each of said valves is 981' occurs. However, if some part of the system were to fail, with the consequent failure of the compensating mechanism, or if for any other reason compensation should not take place and the tilting of the press slide progressed sum ciently to be objectionable or dangerous, one or the other of switches 981 or 881 would be opened by the actuator 99, thus opening the solenoid circuits which include said switches, whereupon the pistons of the several hydraulic distributing provided with itsown centering means. Each of said centering means functions exactly as the centering the first embodiment, the only diilerence being that in the second embodiment centering springs "a, lib, c and d are located within the easings of their related valves. a

The variable fulcrum arrangement already described in detail is preferably employed in connection with both levers "be and 55nd. As, in any compensating movement of the'press slide,

the volume of compensating liquid transferredbetween the liquid supplies of rams Ilb and "c a is muchless than the volume of compensating liquidtransferred between the primary liquid supplies of rams Ila and lid, it isnecessary that the rate of flow ofliquid through the two commeans des ribed in connection with valves would assume their mid positions, thus stopping the movement of the press slide, and

the piston of the air valve 58 would moveto its mid position, this centering the piston of the air motor 58 and shifting the control members of the compensator pumps to neutral or nonpumping position. Thus the switches 981, 981' fimction as safety switches.

It is well known by those familiar with the art relating to hydraulic prases, that suitable means in the form of drain or by-pass ducts or clearances must be provided in certain portions of the 1 various valves and the air motor to prevent locking thereof. Such means, however, are not essential features of the present invention and, therefore, have notbeen fully illustratedrin the drawings.

It should be lmderstood. of course, that the invention may be employed in presses using three 'or five or more rams and that the use of a compensator pump or pumps may be avoided in some installations, by adapting the electric or pneumatic apparatus, or both, to function directly with the pumps provided for supplyingqliquid to the several ram chambers, whereby to effect compensation directly in said pumps.- The invention may be practiced in these and many other ways without, however, departing from the substance I of the invention as defined in the accompanying claims.

- said apparatus comprising a, plurality of pumping systems adapted to pump supplies of liquid separately to each of said chambers, adjustable compensating means, adapted for adjustment independently of said plural pumping systems, for

eifecting compensating variations, during the advance movement of the press slide, in the volume of liquid pumped into said chambers, and an electric control system, adapted to control the adjustment of said compensating means and being responsive, to non-parallelism of the press slide, whereby to cause said compensating means to efiect compensation in the volume of liquid pumped into said chambers to substantially remedy such non-parallelism.

2. Apparatus for controlling the slide movement in a long-bed hydraulic press having two or more symmetrically-disposed slide-actuating rams and related ram advance chambers, the said apparatus comprising a plurality of pumping systems adapted to pump supplies of liquid separately to each of said chambers,transfer means for transferring liquid, during the'advance movement of the press slide, from the said liquid supply of a ram advance chamber located toward means adapted to operate said switch in response to non-parallelism of the press slide.

6.'Apparatus for controlling the slide movement in a long-bed hydraulic press having two i or more symmetrically-disposed slide-actuating rams and related ram advance chambers, the said apparatus comprising a plurality of pumping systems adapted to pump supplies of liquid separately to each of said chambers, compensating means for ellecting compensating variations, during the advance movement of the press slide, in the volume of-liquid pumped into said chambers, and an electric control system, adapted to control the operation of said compensating one side of thepress to the liquid supply of a ram ment in a long-bed hydraulic press having two or more symmetrically-disposed slide-actuating rams and related ram advanced chambers, the

said apparatus comprising a plurality of pumping systems adapted to pump supplies of liquid separately to each ,of said chambers, compensating means comprising pumping apparatus, connected between ram advance chambers at opposite sides of the press slide for effecting compensating variations, during the advance movement of thef press slide, in the volume of liquid pumped into said chambers, and an electric control system,

adapted to control the operation of said compensating means and being responsive to non-parallelism of the press slide; .the said pumping apparatus having flow-controlling means, controlled by said electric system, for. controlling the flow of liquid through said pumping apparatus between said chambers, Whereby'to cause said compensating means to effect compensation in the volumeof liquid pumped into said chambers to substantially remedy such non-parallelism.

4. Apparatus according to, claim 3, further characterized in that the mentioned flow-controling means are adapted to control the direction of flow.of liquid through said pumping apparatus between said chambers and to vary the volume of such flow.

5. Apparatus according to claim 1, further characterized in that the said electric control system comprises an electric circuit, controlling the adjustment of said compensating means, a

said electric control system comprises an electric circuit, controlling the operation of said compensating means, a switch in said circuit, and,

a pair of movable members coacting withthe press slide at opposite sides thereof and with said switch, whereby, through said circuit, to control the operation of said compensating means 7. Apparatus for controlling theslide move-' ment in a long-bed hydraulic press having two or more symmetrically-disposed slide-actuating rams and related ram advance chambers, the said apparatus comprising a plurality of pumping systems adapted to pump supplies of liquid separately to each of said chambers, compensating means for eifecting compensating variations, during the advance movement of the press slide,

in the volume of liquid pumped into said chambers, and an electric control system, adapted to control the operation of said compensating means, and comprising an electric circuit, controlling the operation of said compensating means, a switch in said circuit, a pair of rotatable shafts, and driving means at each of opposite sides of the press. slide, controlled by the movement of the latter and adapted to coact with and separately drive said shafts to degrees which correspond or difier in accordance with the parallelism or non-parallelism of the press slide, the said switch beingcarried upon and constrained to rotate with one of said shafts, and the other of said shafts having a switch actuator constrained to rotate therewith, the said switch and actuator being in non-coacting relationship during the parallelism of the slide but being adapted to coact with each other to operate said switch in response to relative movement occurring between said shafts upon the departure of the press slide from parallelism, whereby to cause said compensating means to efiect compensation in the 1 volume of liquid pumped into said chambers to substantially. remedy such non-parallelism.

trol the said driving means, and, through control of the latter, to control the said compensating means to remedy non-parallelism of the press switch in said circuit, and switch operating slide.

9. Apparatus for controlling the slide movement in a long-bed hydraulic press having two or more symmetrically-disposed slide-actuating rams and' related ram advance chambers, the said apparatus comprising a plurality of pump! ing systems adapted to pump supplies of liquid separately to each of said-chambers, compensating means for effecting compensating variations.

during the advance movement of'thepress slide, in'the volume of liquid pumpeddnto said chambers, and an electric control system adapted to control the operation ofv said compensating means and being responsive to non-parallelism of the press slide, the said compensating means comprising a movable member adapted to con-' trol the said compensating variations, and a fluld-actuatedmotor coasting with and adapted to actuate said movable memberfthe said electric control system being adapted to control the said motor, and, through control of the latter, to

cause said compensating means to effect compensation in the volume of liquid pumped into said chambers to substantially remedy such non-parallelism.

directions and degrees of non-parallelism of the press'siide and adapted to control the supply of .fluid to said separate chambers in; accordance with the direction and degree of non-parallelism of the said slide.

13.- Apparatus for controlling the slide move ment in a long-bed hydraulic press having two or more symmetrically-disposed slide-actuating rams and related ram advance chambers, the said apparatus comprising a pumping system for each of said ram advance chambers, adjustable compensating means, adapted for adjustment independently of said pumping systems, for substantially equalizing the volume of liquid pumped to each of said chambers durlngthe advance movement of the press slide, a fluid actuated motor coacting with said compensating means for adiusting the latter, and motor control means. responsive to non-uniform. advance movement oi the press slide and adapted to control the fluid supply to said motor.

, l0. 'Apparatusmccording to claim 1,. further 'eachresponsive to different degrees of non-parallelism of the-press slide and adapted to con-' trol the mentioned separate'stages of operation of said driving means. 4

11. Apparatus for controlling the slide movement in a long-bed hydraulic press having two or more symmetrically-disposed slide-actuating rams and related ram advance chambers, the said apparatus comprising a plurality or pumping systems adaptedto pump supplies .of. liquid separately to each of said chambers, compensating means for eii'ecting compensating variations, during the advance movement of the press slide, in the volume of liquid pumped into said chambers, and an electric control system, adapted to control the operation of said compensating means, the said compensating means comprising a movable member adapted to control said compensating variations to a degree corresponding substantially to the degree oi movement of said 14. Apparatus for controlling the slide movement in a long-bed hydraulic press having'two or more symmetrically-disposed slide-actuating rams and-related ram advance chambers, the

-- said apparatus comprising a pumping system for neoted between ram advance chambers at. op'po-.

each of said ram advance chambers, compensating means, comprising a reversible pump consite sides 01' the press'slide for substantially equalizing the volume 01' liquid plin'lped to each of said chambers during the advance-movement oi the press slide, a fluid-actuated motor coacting with said compensating means for operating the latter, and motor-control means, responsive to non-uniform advance movement of the press movable member, the apparatus having drivin means, for moving said movable member, comprising a fluid-actuated motor including a casing, and a piston adapted to reciprocate within said casing. the casing having separate chambers for fluid for causing plural stages of movement of said piston in one direction, and the said electric control system having plural circuits, each responsive to different degrees of non-parallelism of the press slide and adapted to control the supply of fluid to said separate chambers in slide and adapted to control the fluid supply to said motor.

'15. Apparatus for controlling theslide movement in a long-bed hydraulic press having two or more symmetrically-disposed slide-actuating rams, and related ram advance chambers, the said apparatus comprising a pumping system for each of said ram advance chambers, compensating means for substantially equalizing the volume of liquid pumped to each of said chambers during the advance movement of the press slide, a fluidactuated motor coacting with said compensating means for operating the latter, and motor control means, responsive to non-uniform advance movement of the press slide and adapted to control the fluid supply to said motor, said motor control means comprising an electric circuit including a switch adapted to be operated in response to non-uniform advance movement of the press slide.

16. Apparatus for controlling the slide movement in a long-bed hydraulic press having two or more symmetrically-disposed slide-actuating rams and related ram advance chambers, the said apparatus comprising a pumping system for each of said ram advance chambers, compensathas plural circuits, each responsive to diflerent ing means for substantially equalizing the volume of liquid pumped to each of said chambers during the advance m'vement of the press slide, a fluid-actuated motor enacting with said compensating means for operating the latter, and motor control means, responsive to non-uniform advance movement of the press slide and adapted to control the fluid supply to said motor, said apparatus being further characterized in that the said motor is capable of plural stages of operation and in "hat the motor control means comprise separat; electric circuits. adapted to separately contrci said stages or operation and in that each of said circuits includes separate switches, eachof said switches being adapted to operate in response to diii'erent degrees of non-uniform advance movement of the press slide.

17. Apparatus for controlling the slide movement in a long-bed hydraulic press having one or more pairs of slide-actuating rams, the members of which pairs are equidistant from the center of said slide and at opposite sides thereof, and relat edpairs of ram advance chambers; the said apparatus comprising separate. substantially similar pumping systems for each of said chambers, adjustable compensating means for each pair of chambers, adapted for adjustment independently of said pumping systems, for substantially effecting compensating variations, during theadvance movement of the press slide, in the volume apparatus comprising separate, substantially similar pimping systems for each of said diambers, adjustable compensating means for each pair of chambers, adapted for adjus ment independently of said pumpin systems, for substan- Qtially efiecting compensating variations, during the advance movement of the press slide, in the volume of liquid pumped into the paired chambers, a fluid actuated motor coasting with said compensating means for adjusting the latter, and motor control means, responsive. to non-uniform advance movement of the press slide and adapted to control the ham supply to said motor.

19. Apparatus for controlling the slide movement in a long-bed hydraulic press having two or more symmetrically-disposed slide-actuating rams and related ram advance chambers, the said apparatus comprising a plurality ,of pumping systems adapted to pump supplies of liquid separately to each of said chambers, compensating means for effecting compensating variations during the advance movement of the press slide,

in the volume of liquid pumped into said chambers, an electric operating circuit including a safety switch, for controlling the said advance movement, an electric compensation-control circuit including a control switch, for controlling v the operation of said compensating means, and a pair of movable members, adapted to derive movement relatively to each other, in response to non-uniform advance movement of the press slide, through coaction with opposite sides of the said'slide. one of said movable members having a portion constituting a switch actuator and the other oi said members having said control switch and saidsafety switch fixed thereon along the path followed by said actuator during such relative movement, the said control switch being adapted to be operated by said actuator upon-a predetermined degree oftilting oi the press slide and the said safety switch being adapted to be operated by said actuator upon tilting of the press slide beyond a. predetermined degree of tilting, whereby to cause said operating circuit tostop the advance movement of the press slide.

20. Apparatus for controlling the slide movement in a. hydraulic press having an electric circuit adapted to control the closing movement of the press slide, the said apparatus q prising a pair of movable members, adapted to derive movement relatively .to each other, in response to non-uniform advance movement of the press slide, through coaction with opposite sides of the said slide, and a switch, in said circuit, carried upon one of said members, a portion of the other of said members being adapted, during such relative movement, to engage and operate said switch whereby to cause said electric circuit to stop the movement of the press slide.

' EARL CANNON.

CERTIFICATE OF CORRECTION.

Patentl lo. 2,555,388. July 11, 19M.

EARL CANNON.

it is hereby certified thai; error appears in the print'ed-spcificgtion ofthe above numbered patent requiring correction as follows: Page 9', sec

0nd column, QLine 55, claim 15, after the word. "movement" insert -*-0'f oppo- .s1te sides---- and that the said Letfiers Patent should be read with this correction izhereinthat the seme may conform to the record of the case in the Patent Office.

Signed and sealed this 22nd day of Au ust, A... D". 191 1 Leslie ,Frazer (Seal) Acting Commissioner of Patente.

US463604A 1942-10-28 1942-10-28 Apparatus for controlling the slide movement in long-bed hydraulic presses Expired - Lifetime US2353388A (en)

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2526252A (en) * 1944-03-20 1950-10-17 Mercier Jean Hydraulic control mechanism
US2558071A (en) * 1946-05-03 1951-06-26 Jr James B Castle Electrohydraulic control means for machines employing plural hydraulic motors
US2603145A (en) * 1950-04-25 1952-07-15 Edward M Dreis Leveling mechanism for hydraulically actuated press brakes
US2616265A (en) * 1949-08-24 1952-11-04 Robert C Wilson Means for adjusting fluid motor elements to maintain synchronized movement
US2932171A (en) * 1957-11-04 1960-04-12 Cutler Hammer Inc System for raising and lowering large movable structures
US2958199A (en) * 1959-03-12 1960-11-01 Cleveland Crane Eng Hydraulic press
US2960828A (en) * 1957-03-22 1960-11-22 Gardner S Gould Fluid pressure power system
US2978976A (en) * 1959-01-21 1961-04-11 Cincinnati Shaper Co Level control for press brakes and the like
DE1125280B (en) * 1955-07-20 1962-03-08 Us Industries Inc Synchronization control for hydraulic presses, especially sheet metal presses
US3031950A (en) * 1959-06-05 1962-05-01 Cleveland Crane Eng Hydraulic press
DE1133246B (en) * 1955-04-18 1962-07-12 Scharringhausen Maschb Ges M B Control of piston valves that regulate the pressure medium inflow and outflow on two or more working cylinders of hydraulic presses for automatic parallel guidance of the movable press beam
US3280610A (en) * 1963-09-20 1966-10-25 United States Steel Corp Roll-positioning mechanism
US3355994A (en) * 1966-01-13 1967-12-05 New York Air Brake Co Hydraulic system
US3763690A (en) * 1972-04-17 1973-10-09 Dreis & Krump Manuf Co Press brake ram leveling
US4406726A (en) * 1981-05-11 1983-09-27 Peter Lisec Apparatus for producing compacted insulating glass having parallel planar faces
US4649705A (en) * 1985-05-14 1987-03-17 Clark Equipment Company Composite hydraulic system
DE8714804U1 (en) * 1987-11-06 1987-12-23 Gottfried Joos Maschinenfabrik Gmbh & Co, 7293 Pfalzgrafenweiler, De

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2526252A (en) * 1944-03-20 1950-10-17 Mercier Jean Hydraulic control mechanism
US2558071A (en) * 1946-05-03 1951-06-26 Jr James B Castle Electrohydraulic control means for machines employing plural hydraulic motors
US2616265A (en) * 1949-08-24 1952-11-04 Robert C Wilson Means for adjusting fluid motor elements to maintain synchronized movement
US2603145A (en) * 1950-04-25 1952-07-15 Edward M Dreis Leveling mechanism for hydraulically actuated press brakes
DE1133246B (en) * 1955-04-18 1962-07-12 Scharringhausen Maschb Ges M B Control of piston valves that regulate the pressure medium inflow and outflow on two or more working cylinders of hydraulic presses for automatic parallel guidance of the movable press beam
DE1125280B (en) * 1955-07-20 1962-03-08 Us Industries Inc Synchronization control for hydraulic presses, especially sheet metal presses
US2960828A (en) * 1957-03-22 1960-11-22 Gardner S Gould Fluid pressure power system
US2932171A (en) * 1957-11-04 1960-04-12 Cutler Hammer Inc System for raising and lowering large movable structures
US2978976A (en) * 1959-01-21 1961-04-11 Cincinnati Shaper Co Level control for press brakes and the like
US2958199A (en) * 1959-03-12 1960-11-01 Cleveland Crane Eng Hydraulic press
US3031950A (en) * 1959-06-05 1962-05-01 Cleveland Crane Eng Hydraulic press
US3280610A (en) * 1963-09-20 1966-10-25 United States Steel Corp Roll-positioning mechanism
US3355994A (en) * 1966-01-13 1967-12-05 New York Air Brake Co Hydraulic system
US3763690A (en) * 1972-04-17 1973-10-09 Dreis & Krump Manuf Co Press brake ram leveling
US4406726A (en) * 1981-05-11 1983-09-27 Peter Lisec Apparatus for producing compacted insulating glass having parallel planar faces
US4649705A (en) * 1985-05-14 1987-03-17 Clark Equipment Company Composite hydraulic system
DE8714804U1 (en) * 1987-11-06 1987-12-23 Gottfried Joos Maschinenfabrik Gmbh & Co, 7293 Pfalzgrafenweiler, De

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