US2300338A - Hydraulic press and the like - Google Patents

Description

Oct. 27, 1942- A. CAMEROTA ETAL 0 HYDRAULIC PRESS AND THE LIKE Filed Oc t. 3, 1940 4 Sheets-Sheet 1 INVENTORS: Louis fl. Cam/61 0M wcefll owell,

Arm

Oct. 27, 1942.

[ A. CAMEROTA ET AL HYDRAULIC PRESS AND THE LIKE Filed Oct. 3', 1940 4 Sheets-Sheet 2 1 N mvNhN INVENTORS.

' CZrmceEiPow eZL LLAQ T'ToRNEYsf Oct. 27, 1942- L. A. CAMEROTA ETAL 2,300,338v

HYDRAULIC PRESS AND THE LIKE Filed Oct. 3, i940 4 Sheets-Sheet 3 WITNESSES: INVENTORS;

Louis ,4. L'ameroia Oct. 27, 1942. L. A. CAMEROTA EI'AL HYDRAULIC PRESS AND THE LIKE Filedoct. 3, 1940 4 Sheets-Sheet 4 I LouiSfl.CamemZa Mum By 46ZareaceEPowgZl,

WWZZWM Patented Oct. 27, 1942 E. Powell, Philadelphia, Pa.,

assignom to Florence Pipe Foundry & Machine Company, Florence, N. J., a corporation of New Jersey Application October 3, 1940, 'SerlalNo. 359,532

11 Claims. (CI. 60-51) This invention relates to machinery operated by fluid pressure, such as presses and the like, and more particularly to the provisions for supplying and controlling the operating or working fluid for such machinery. The general purpose of the invention is to improve and simplify the fluid supply and control system,and to simplify and facilitate the manipulation of the control for various operations. The invention is of special advantage for presses employing difierent working fluids, or fluid at diiierent pressures, and for presses adaptable for diverse modes of operation. We have hereinafter explained the invention in' connection with a metal-working hydraulic press using inelastic fluid at high and low pressures as its ,working fluid, and adaptable for themodes of operation distinctively known" in the art as cogging" and forging." In this particular press, the opposite movements of the press head are produced by separate single acting pistons of plunger type, operating in separate cylinders; but it will be understood that the invention is equally applicable to presses having other types or arrangements of piston means or the like for producing the movement of the press head, such as an ordinary double-acting piston on a piston rod, for example.

In cogging, the press operates under high pressure to slowly squeeze out or crush a relatively large (hot) metal billet or ingot between flat surfaces for the purpose of reducing its crosssection or of changing itsshape. It is desired to control the movement of the press quite accurately; and the working fluid is generally used at relatively high pressure for both the working and the return (or closing and opening) movements or strokes of the press head or platen with respect to the work and the bed of the press.

In forging, a (hot) metal blank is pressed to shape between dies; and it is desired to have the press move quite rapidly in one direction, at least (usually the working or closing movement),

until the resistanceof the blank or work is encountered by the moving'press head or platen,

and thereafter to apply high pressure to shape the metal while the working movement or stroke is being completed. Accordingly, part of the press movement is generally efiected by working fluid at relatively low pressure, and part by fluid at high pressure.

Heretofore, it has been necessary to provide a press for cogging and forging with two separate systems of piping and valves for supplying, venting or exhausting, and controlling the high pressure fluid and the low pressure fluid. For operating the controls, there have been a plurality of levers to be manipulated; and severe effort has" been required of the operator in manipulating them properly.

Our invention permits, amongst other advantages, of simplifying the fluid supply and control system and its operation, eliminating the necessity of double piping and valve systems such as heretofore used, as well as the necessity of manipulating a number of control levers in operating the press. The physical exertion of manipulating the controls may also be very greatly reduced. In the system herein particularly illustrated and described, the control is efiected by a single easily moved hand lever for both cogging and forging operations; and an auxiliary selector shiftable by an easy movement of the hand adapts the press for either cogging or forging, as desired.

Various features and advantages of the invention will appear from the following description of a species and'form of embodiment,gand from the drawings. All the features and combinations shown and described are of our invention, so far as novel; and it will be understood that various such features or combinations herein disclosed may be used separately from the rest, in

presses quite different from that here illustrated.

In the drawings, Fig. l is a general diagrammatic view of a hydraulic press with a working fluid supply and control system conveniently embodying our invention, the control system being adjusted or set for cogging; and Fig. 2 is a similar view with the control system set for forging. In these figures, adjustable shoes on the valve stems of the main control valves are shown in section.

Figs. 3, 4, 5, and 6 are diagrammatic views' of the main operating valve means of the fluid supply and control system, showing their positions in various stages of the cogging operation of the press; and Figs. 7, 8, 9, l0, and 11 are diagrammatic views of the main operating valve means and supplemental valve means, illustrating various stages in the forging operation of the press.

by and between which the metal 'billet, ingot, or

platen l'l moves vertically up and down relative thereto. Cylinder and piston means 20 2| are shown for imparting the downward working movement to the head i1; and for imparting the upward return movement to said head l1, there are cylinder and piston means 22, 23, here shown in duplicate. The piston means 2|, 23 are illustrated as simple rams or plungers of uniform diameter. For the downward working movement of the head I], pressure fluid is admitted to the cylinder 20, and may be concurrently vented from the cylinders 22; while the upward return moveworkW acted on. As shown, the lower head or press bed It is fixed. and the upper head or pipeconnection 43to1the upper portion of said reservoir. The reservoir 44 is. preferably eq ipped with a liquid overflow pipe 50 having therein an overflow check-valve 5|. As shown, the reservoir 44 is also provided with a gauge glass 32,

an excess air pressure relief valve 53, connected tions of press operation when the high pressure fluid is shut-oil and low pressure working fluid is' to be used in the cylinder 3|! (for rapid unresisted movement of the head ll) the valve 40 is openduring both the return and working movements of the head ll. When the valve 4|) is thus open, upward return movement of the plunger 2| into the cylinder (due tothe acequalizer 21 .is shown interposed, comprising a closed chamber having its bottom connected into the pipe line 26, and containing a body ofair or other elastic cushioning fluid above the water or other (inelastic) working fluid. A springactuated hydraulic shock absorber 23 may also be interposed in the pipe line 2i, preferably in advance of most of the connections thereto. The connections to the pipe line 23 include a branch (in which may be interposed an adjustable 1 control throttle valve 3|), for supplying high pressure fluid through the main operating valve means 32 (and a pipe line 33) to the main working cylinder 23 and its piston means 2!, and also 4 (through a pipe line 34) to the return cylinders 22 and their piston means 23; another branch 35 for also s pp y n h h pressure fluid "to the. return cylinders and piston means 22, 23 (through connections hereinafter described, including an admission and ventpipe '33); a branch 31 for supp yin high pressure fluid, :through the selector valve means .38 and other connections hereinafter described, to certain supplemental and auxiliary control valves 40, 4|, 42 of the system; and a (continuation) branch '43 for supplying high Pressure. fluid to; one of said auxiliary control tion of the plungers 23, 23) forces working liquid through the pipe lines 45, 33 into the reservoir 44, thus increasing the air pressure in said reservoir; while during the downward movement of the press head II, when working fluid is being vented from the return cylinders 22, 22, the accumulated pressure of the air in the reservoir 44 forces liquid back through the pipes 33, 45

into the cylinder 20 to produce (or permit) downward movement of the head I L As shown, the valve 40 is fluid-operated, having its stem connected to the rod of a piston 16 in a cylinder whose ,upper end is connected to a branch 51 from the pressure supply and exhaust pipe 36 of the cylinders 22, and whose lower end has a double pipe connection to the auxiliary (three way) valve 4| already mentioned,

into the cavity between its double valve seats.

valves. 'As shown, the shock absorber 28 isconnected in the pipe line 23 in advance of all of these branches, excepting the branch 31 to the selector valve means 38..

Besides the supply of high pressure working fluid through the pipe line 26, provision is also made for a supply of low pressure fluid, for rapid (unresisted) movement of the head or platen 11. As shown, this supply of low pressure fluid is not taken from .an independent source, but is derived from the supply of high pressure fluid, through the action of the press .on one of its movements. ,For this purpose, there is shown in Fig. 1 a pressure reservoir or tank 44 arranged for connection to the cylinder "through a pipe line 45, which maybe connected to the high pressure fluid pipe line '33 from themain operating valve means 32 to said cylinder. In this pipe line 4-5 is interposed the supplemental control valve 40 already referred-to, and also a shut-oil valve 41. The reservoir 44 normally contains a suitable'amount of water or other working liquid, as wellas a body of air or other elastic cushion fluid above the water. Liquid may be introduced into the reservoir- 44 (or withdrawn, if required) through a; valved outlet pipe 48 from its bottom, and .compressed air to any desired pressure may be introduced through a valved One branch of the double connection 60 has a check-valve ii which only permits outflow from beneath the piston 56, while the other branch is shown provided with a shut-oil and regulating valve 32. Thus the outflowof fluid from beneath the piston 53 is freer than the inflow. The normally-closed valve 40 responds to the pressure admitted beneath the piston 56 by the auxiliary valve 4|, as well as to the pressure conditions (of admission or exhaust) in the cylinders 22; but as the area of the lower side of the piston i8 exceeds that at its upper side by the sectional area of its rod 55, the valve 40 tends to open when these pressures are equalized. Being as shown, an unbalanced (disc) valve, the valve.-

40 behaves as a check-valve whenever thepressures aflecting the piston '56 permit:- i. e., it

tends to close with (and prevent) outflow from the cylinder 20.

The auxiliary valve 4! and its operation will be further explained hereinafter.

The main operating valve means 32 controls the admission or supply of high pressure fluid to the main working cylinder and piston means- 20, 2|, and the venting or exhaust of the spent fluid therefrom, both through the pipe line 33. Besides this, the valve means 32 also controls the supplying and venting of high pressure working fluid to and from the return cylinder and piston means 22, 23 (under certain operating condimultiple valve devices 66,- are provided for I supplying and venting working fluid to and-from the cylinder 20 through the pipe line 33: i. e.,

the valve device 36 for admitting and exhausting fluid slowly, for relatively slow movement of the press |5, and the valve device 81 for admitting and exhausting-fluid freely and rapidly, for more rapid movement of the press. These valve devices 85, 88, and 81 may comprise separate fluid admission and exhaust valves of inverse flow plunger and disc type. The valves 88a. 85a, 88a, 88c, 81a, 81c may be normally held to their seats, as shown in Fig. 1, by any suitable means acting on the valve plungers, here indicated by a helical compression spring 88 acting on the upper end of the plunger of the valve 85c, and by cylinders into which the upperend of the other plu'ngers extend, and to which high pressure fluid is constantly supplied through connections from a pipe line 88 that is itself connected into the pipe line 38.

High pressure fluid may be supplied to all three of the admission valves 85a, 88a, 81a through a duct I8 forming a continuation of the supply branch 38 and-delivering into the cavities around the (reduced) valve stems below the valve seats. The cavities above the seats of the exhaust valves 85c, 88c are shown connected to a. common vent or exhaust duct II, and the cavity above the seat of the exhaust valve 81c is connected to a larger exhaust duct 12. Ducts l3 connect the cavities above the seats of the admission valves 85a, 88a, and Bid with the cavities below the seats of the exhaust valves 85c, 88c, and 8'le, respectively. The cavity above the seat of the admission valve 880 and the cavity below the seat of the exhaust valve 8'Ie are connected to the admission and exhaust line 33 of the cylinder 28. The cavity abovethe .seat of the admission valve 85a is connected to the pipe line 34 which under certain conditions serves the cylinders 22,- at will presently be explained.

Cam means for operating the'valve devices 85, 88, 81 in proper sequence are diagrammatically represented in Figs. 1 and 2 by three-armed rockers 11 whose lower, arms are interconnected by a link rod 18. The upper arms of the rockers 11 are shown provided with anti-friction rollers for engaging (adjustable) shoes on the lower ends of the plungers of the valves 85a, 85c, 88a, 88c, 81a, 8ie. The clearances between the valveplunger shoes and the rockerrollers correspond to the sequence in the operation of the several valves that is described hereinafter. For operating the rockers 11., there is shown a lever or crank arm I9 fast on the pivot shaft of the rocker ll of the valve device 61.

For manually operating the whole main valve means 32 and controlling both cogging and forging operation of the press l5, there is shown a swingable hand lever 88 mounted for rocking movement on a fixed support 8|, andvpreferably associated with a locking segment 82 notched to lock the lever 88 in a vertical neutral position N (shown in full'lines), or in positions d, D, and u, U, to either side. which are indicated in dot-and-dash lines. In the present instance, the hand lever 88 does not operate the lever arm 18 above described directly, but through a servomotor 84 whose piston rod is (pivotally) connected at 85 to said lever arm 18. ,For this purpose, a-crank arm 88 fast on the shaft of the hand lever 88 is connected by a link rod 81 to one end of a lever 88 which is pivoted at 89, intermediate its ends, to the stem of the controlling piston valve 98 for the servo-motor 84. The lever 88 is without a fixed fulcrum, having its other end pivoted to the lever arm 19, and (as shown) on the same pivotal axis 85 by which the piston rod is pivoted to said lever arm 18. Thus the floating lever 88 serves as a follow-up to return the valve 88 to mid-position and stop the servo-motor 84 as soon as the latter has made a movement proportionate to the actual movement of the hand lever 88.

As here shown, the servo-motor 84 is of the hydraulic type, and is supplied with operating fluid under pressure (preferably 011), between the pistons of -its valve 88, through a pipe line 8| (to which a pressure gauge is shown connected) from a pump 82 drawing from a reservoir tank 93 and driven by an (electric) motor 84. The spent liquid exhausted from the opposite ends of the piston valve returns through a (branched) pipe line 85 to the reservoir 83. I

The- pipe lines 34 and 35 herelnbefore mentionedserve the cylinders 22 alternatively, according to the conditions of operation: the pipe line 35 for cogging operation of the press, and

the pipe line 84 for forging. The use of one connection or the other is determined by the auxiliary (three-way) valve 42 already mentioned, and accordingly the pipe lines 34, 35 are connected to the cavities of this valve 42 at opposite sides of its double valve seats, while the (branching) pipe line 38 to the cylinders 22 is connected to the cavity of said valve 42 between the seats. A pressure relief valve 91 is also preferably connected to the pipe line 38. a

-The auxiliary three-way valves 4| and 42 are so interrelated in operation that they can best be described and explained together. Each of these valves 4|, 42 has a middle. cavity with double valve seats, and a valve body member seating on the two seats alternatively. Each valve 4|, 42 is continually urged. to seat on one (the lower) seat by a constantly acting force: in the case of the valve 4|, high pressure fluid supplied through the pipe 43 to a cylinder into which. the upper end vof the valve plunger extends; and in the case of the valve 42, a helical compression spring 88 acting between the upper end of the valve plunger and a fixed abutment carried by the valve casing. The valve-body of each valve 4|, 42 is moved the other way (upward) by fluid pressure in a cylinder acting on the (enlarged) lower end of the valve plunger,

pressure being admitted to the cylinders through pipes I88. |8| under control oil the selector valve means 38. The connections 34, 35, 38 to valve 42 have already been described. Besides ,the connection 88 to the cavity between its seats 1 above its own upper seat, with a check-valve I84.

and the selector pipe connection I88 to its aforementioned (lower) operating cylinder, the valve 4| has a branch pipe connection I82 from the. pipe 84 (which is connected as already mentioned, to the cavity of' the valve 42 above its upper seat),.and a branch pipe connection I83 from the pipe I88 to the cavity of said valve 4| therein that only permits return flow from the valve 4| through the pipe |88..

It will be seen therefore, that when the selector 38 admits fluid pressure to the pipe IN and vents the pipe I88, the valve body of valve 42 is raised and held to its upper seat, .as shown in Fig. 1, admitting constant fluid pressure from the pipe line 35 to the cylinders 22, and preventing access of fluid pressure beneath .the lower seatof the valve 4|; while the valve body of-valve 4| is de pressed and held to its lower seat, as in' Fig; l,

permitting outflow of fluidfrom beneath piston 58 of valve 48, so that this valve may close under pressure coming from pipe line 33. When, gon

v the other hand, the selector valve means 33 admits fluid pressure to the pipe I and vents it fromthe pipe IN, the valve 42 is depressed and held down as in Fig. 2, connecting the pipe line 34 controlled by the valve device 85 to the cylinders 22; while the valve H is raised and held up as in Fig. 2, shutting off pipe I00 from pipes 50 and connecting the latter to the said pipe line 34. So

.though the relative positions of the admission and exhaust valves I 350, le, and I08a, I0ie are interchanged as compared with those of the valve devices 65, 68, and their pressure supply and exhaust connections 31 and I01 are correspondingly changed. The valves I05a, I05e, I05a, I05e may all be normally held to their seats by any suitable means acting on the valve plungers, here indicated by helical compression springs. For operating the valve devices I05, I06, there are two three-arm rockers I00, I08 whose lower arms are interconnected by a link-rod I09 which is also connected to a swinging actuating hand-lever IIO fulcrumed on any suitable support III. The upper arms of the rockers I08, I08 are shown provided with anti-friction rollers for engaging the lower ends of the valve-plungers I05a, l05e. and I00a, I0ie. By throwing the lever IIO to one extreme position 0 as in Fig. l, the system is set for cogging; by throwing it to the other extreme F, as in Fig. 2, it is set for forging.

It will be understood, of course, that the application of fluidthrough the pipe connections I00, IOI under control of the valve devices I05, I08 is only an illustrativemode of operative connection from the selector lever IIO for actuating the auxiliary valves 4I, 42.

To prepare the press for operation, water at relatively'low pressure is supplied to the slack water tank or reservoir 44 through the valved to the position u in Fig. 3, thus lifting the small pipe 48, and compressed air to a suitable pressure is supplied to said reservoir through the valved pipe 43. The gate valve 41 being open, sufllcient water is forced through the pipe lines 48, 45 (and 33) to fill the cylinder 20 and the pipe line 33. Throttle valve 3| being now opened, liquid under high pressure is supplied through the pipe lines 20 and 30. w

For cogging, the selector lever H0 is set in the position shownin Fig. 1. In this condition, the valve body of the auxiliary valve 42 is in its upper position, and pressure is constantly supplied through the pipes 35,. 30 to the return cylinders 22, constantly tending to raise the head or platen I'I, pipe 36 and cylinders 22 being at this time shut-oil from pipe line 34. Hence any operation of valve device 55 to admit pressure fluid to pipe 34 or to vent the latter is migratory and without effect on thepress during cogging: i. e., cogging is controlled solely by the valve devices 06, 61. As the valve body of the valve II is depressed and held down by the constant pressure supplied through .the pipe 43, fluid is constantly vented from the lower side of piston 50 (through pipe lines 80 and I80) and is constantly supplied above 1 it (through pipe lines a, rs, and s1), sothat valve 40 is held closed under all conditions of cogging operation.

controlled by the valve device 55.

exhaust valve 60c and allowing fluid from the cylinder 20 to exhaust slowly (through pipe line 33). This allows the high pressure fluid constantly supplied to the cylinders 22 (through pipe line 35, valve 42,. and pipe 36) to slowly lift the movable press head I! away from. the flxed press head I6. When the lever 80 is moved further to valve 88c remains open and the larger exhaust valve We is also opened, allowing rapid exhaust of fluid from the cylinders 20, (since the exhaust passage afforded by the valve 01a is equal to the full capacity of the pipe line 33), and rapid upward movement of the press head II.

This upward movement of the press head Il may be slowed down whenever desired by returning the lever 80 toward the left, to the position u, and may be stopped by returning the lever 80 to its neutral position N, thus closing all the valves of the main valve means 32, and restoring the system to its general condition in Fig. l, with the press head I'l locked in the position to which it has been moved.

To lower or force down the press head II, the lever 80 is moved to the left from its neutral position N in Fig. 1 to the position din Fig. 5, thus lifting the small pressure admission valve 360 off its seat and admitting high pressure fluid in small quantities to the cylinder 20 (through the pipe line 33). The area of the piston 2I being greater than the total aggregate area of the pistons 23,

the press head I! is moved slowly downward toward the fixed head I6 against the pressure constantly supplied to the cylinders 22 (through the pipe line 28, valve 42, and pipe line 38). When the lever 80 is moved further to the left, to the position D in Fig. 6, the small admission valve 080 remains open and the larger pressure admission valve .Gla is lifted off its seat, thus admitting high pressure fluidin larger quantities to the cylinder 20 and causing the press head I! to move downward more rapidly and forcibly.

This downward movement of the press head I! may be slowed down by returning the lever 80 to vthe right from position D to position d, and may be stopped by returning it to itsneutral position N, thus restoring the system to its condition in Fig. -1 and locking the press head I! in the position to which it has been moved. To raise the press head I! again, it is only necessary to move the lever 80 to the right beyond the neutral position N, asalready explained.

For -orging," the selector lever H0 is moved to the left, from the position C shown in Fig. 1 to the position F shown in Fig. 2. This permits fluid to exhaust through the pipe line I0 I, so that the, valve body of valve 42 is forced downward by the spring 83 to its lower seat, as shown in Fig. 2,

shutting off the constantly open pipe line 35 from the pipe line 38 and placing the latter in communication with the pipe line 34, which is With this setting of the selector valve means 38, also, fluid is supplied through the pipe line I00 to lift and hold the valve body of valve M to its upper seat, as shown in Fig. 2, so that the pipe line "and the lower side of the piston 56 are in communication with the pipe line 34. Accordingly, the valve device 65 is effective to control the operation of the press in forging, as hereinafter explained.

So long as the main valve means 32 remains closed, as shown in Fig. 2, no fluid is supplied to the lower side of the piston 56 of valve 40, or to either of the cylinders 20 or 22, so that the press head I! remains locked in position as shown in Fig. 2.

When the lever 80 is moved a short distance to the right, from its neutral position N in Fig. 2 toward its position u, as shown in Fig. '7, the small exhaust valve 66a is lifted from its seat, releasing the pressure in the cylinder 20 (through pipe line 33). This, however, does not result in admitting pressure fluid (through the pipe lines 34 and 36) to the cylinders 22, and so the press head I! still remains stationary. But when the lever 80 is moved further to the right, to the position it in Fig. 8, the small admission valve 65a is opened to supply' high pressure fluid (through pipe line 34, valve 42, and pipe line 36) to cylinders 22, and pressure is also admitted (through pipe I02, valve 4|, and pipe 60) beneath piston 56 of valve 40. Since the area at the lower side of this piston 56 is greater than that at its upper side (by the diameter of its stem-rod 55), said piston 56 rises and opens the supplemental valve 40, which allows the pressure in the cylinders 22 to lift the press head I'l slowly and expel liquid from cylinder 20 (through the pipe lines 33 and '45) into the reservoir 44, increasing the air pressure in said reservoir. This rising movement of the press head I! is sufliciently rapid for forging purposes, so that it is never necessary to move the lever 80 still further to the right, to the position U of Fig. 1. While the small exhaust valve Elie remains open at this time and vents fluid from the pipe line 33, this small loss of fluid does not materially afiect the flow through the much larger valve 40 into the reservoir 44.

Returning the lever 80 to the left from the position u in Fig. 8 to its neutral position N in Fig. 2 will close the valves 66a and 65a, restoring the system to its condition in Fig. 2, and locking the press head i! in the position to which it has been moved.

Moving the lever 80 to the left from its neutral position N in Fig. 2 toward the-position d as shown in Fig. 9 opens the small exhaust valve 65e, thus venting the cylinders 22 through the pipe lines 34 and 36, and also equalizing the pressure above and below the piston -56 oi valve 40. The supplemental valve 40 therefore rises and opens (as a check valve) owing to the venting of the cylinders 22 and the suction created by the plunger 2|, due to the weight of this plunger and the associated parts, or under pressure existing in the reservoir 44. The pressure previously stored in the reservoir is thus admitted (through the pipes 45 and 33) to the piston 2| in the cylinder 20, so as to force the press head i! downward. When the press head I! engages the work W on the stationary head IS, the resistance thus encountered stops the movement of the press head l1 and the flow of fluid upward past the valve 40, which may then close by its own weight, cutting off the cylinder 20 from the reservoir 44, as shown in Fig. 10. Movement of the lever 80 further to theleft, to

to the cylinder 20, thus exerting a force upon the work W which ordinarily suflices to compress and flatten it, or otherwise change its shape as desired. As soon as the valve 66a is thus opened,

the presure thereby created in the pipe 45 causes I the valve 40 to close, if it has not done so already. Movement of the lever 80 yet further to the left, to the position D in Fig. 11, lifts the larger pressure admission valve 61a off its seat (in addition to the admission valve 66a), permitting full flow of high pressure fluid into the cylinder to exert maximum force on the press head l1 and on the workW. I

If not reviously closed as above mentioned, the valve closes (as a check-valve) when the opening of valve 66a creates pressure in the pipe and a tendency toward back flow into the I reservoir 44, or, at any rate, when the opening of the larger valve 61a tends to create a more powerful backflow in said pipe 45. In this latter case, the gentle backflow through pipe 45 after valve 66a opens results in an accumulation of pressure in reservoir 44 before valve 61a opens and creates a sufficiently vigorous backflow to close valve 40. Which. of these actions occurs may depend on the design of the valve 40 and its piston 56, as well as on the exact operating conditions and pressures, including the adjustment of various valves 41, 62, etc.

Returning the lever 80 from the position D to the position it slows the downward movement of the press head H, or if the resistance of the the position 12 in Fig. 10, lifts the small pressure admission valve 66a of: its seat and admits high pressure fluid slowly (through the pipe line 33) work W is great enough, even arrests such downward movement. Returning the lever to the neutral position N restores the system to its position'in Fig. 2, with the press head I1 arrested and locked in the position to which it has been moved. To raise the press head I! from the work W, it is only necessary to move the'lever 80 to the right to its position u, Fig. 8,. as already explained.

Having thus described our invention, we claim:

1. In a press of the character described, the combination with a moving press head or platten and pistonmeans for imparting to said head its working and return movements, and means for supplying working'fluid under pressure for moving said head; of operating valve means for controlling the supply and venting of working fluid at a relatively low rate inland from said piston means for movement of said head in opposite directions, operating valve means for controlling the' admission and venting of working fluid at a relatively high rate to and from said piston means for movement of said head in opposite; directions, and other. operating valve means for controlling the venting and admission of working fluid to and from said piston means in reverse correspondence with the admission and venting'of working fluid by the aforesaid operating valve means alternative means for admitting fluid to said piston means to urge said head in the direction of the movement produced by admission of fluid by the last-mentioned operating valve means; and means for either connecting said alternative means to said piston means and shutting ofi connection of said other operating valve means thereto, or vice-versa.

2. In a press of the character described having divers modes of operation, the combination with a moving press head or platten and piston means for imparting to said head its working and return movements, and means for supplying working fluidof different pressures for moving said head; of operating valve means controlling the supply and venting of fluid to and from the piston means for one of said movements of said head during divers modes of operation, but controlling the supply and venting of fluid to and from the piston means for the opposite movement of said head during only one mode of operation; selective means for determining the mode of operation of the press; and supplemental valve means controlling the connection of one of said fluid supplies to the piston means for one of said movements, and itself controlled by said selective means.

3. In a press of the character described, the combination with a moving press head or platten and piston means for imparting to said head its working and return movements, and means for supplying working fluid of different pressures for moving said head; of operating valve means for controlling the supply and venting of higher pressure fluid to and from the piston means for producing the movements of said head; fluidoperated supplemental valve means controlling the action of lower pressure fluid on said piston means, and itself controlled by said operating valve means; alternative means for supplying working fluid to the cylinder and piston means for moving said head, with auxiliary valve means controlling said alternative supply means; and

I of operation of the press and the control or non- 2,eoo,sse

ling the connection of one of said fluid supplies to the piston means for one of said movements when the fluid supply to said latter piston means is controlled by'said operating valve means.

6. Ina press of the character described having divers modes of operation, the combination with a moving press head or platten and piston means for imparting to said head itsworking and return movements, and means for supplying working fluid of different pressures for moving said head; of operating valve means controlling the supply and venting of fluid to and from the piston means for one of said movements of said head during divers modes of operation, but controlling the supply and venting of fluid to and from the piston means for the opposite movement of said head during only one mode of operation; selective means for determining the mode control of the fluid supply for the last-mentioned movement of said head by said operating valve means; and supplemental valve means controlling the connection of one of said fluid supplies to the piston means for one of said movements, and itself controlled .by said selective means and by the pressure producing the other of said movements under control of said operating valve means.

selective means controlling said auxiliary valve means and the action of fluid on said supplemental .valve means. '4. In a press of the character described having divers modes of operation, the combination with a moving press head or platten and piston means-for imparting to said head its working and return movements, and means for supplying working fluid o! difierent pressures for moving said head; of operating valve means controlling the supply and venting orfluid to and from the piston means for one of said movements of said head during divers modes of operation, but controlling the supply and venting of fluid to and from the piston means for the opposite trolled by said selective means and by pressure acting on said piston means under control of said operating valve means.

i 5. In a press of the character described having divers modes of operation, the combination with a moving press head or platten and piston means for imparting to said head its working and return movements, and means for supplying working'fluid of different pressures for moving said head; of operating valve means controlling the supply and venting of fluid to and from the piston means for one of said movements of said head during divers modes of operation. but controlling the supply and venting of fluid to and from the piston means for the opposite movement of said head during only one mode of operation; selective means for determining the mode of operation of the press and the control or noncontrol of the fluid supply for the last-mentioned movement of said head by said operating valve means; and supplemental valve means control- 7. In a press of the character described, the combination with a moving press head or-platten and, piston means for imparting to said head its working and return movements, and means for supplying working fluid under relatively high pressure for moving said head; of operating valve means for admitting fluid to the piston means for the movement of said head one way, and venting it therefrom during the reverse movement of said head; operating valve means for admittin fluid to the piston means for said reverse movement of said head, and venting it therefrom during the first-mentioned movement; alternative means for admitting fluid to the piston means to urge said head in the direction of said reverse movement; a liquid and gas pressure reservoir with connection for receiving and accumulating fluid from the above-mentioned supply at relatively low pressure; supplemental valve means controlling admission of the accumulated low pressure fluid to the piston means for the flrstmentioned movement of the head, and responsive to fluid pressure controlled by said last-mentioned valve means; and selective means for determining whether fluid is admitted to the piston means bysaid alternative means, or admitted and vented by the last-mentioned operating valve means, and also coacting with said lastmentioned operating valve means to control said supplemental valve means.

8. In a press of the character described, the combination with a moving press head or platten and piston means for imparting to said head its working and return movements, and meansfor supplying working fluid under pressure for moving said head; of operating valve means for controlling the supply and venting of working fluid at a relative low rate to and from said piston means for movement of said head in opposite directions, operating valve means for controllin the admission and venting of working fluid at a relatively high rate to and from said piston means for movement of said head in opposite directions,

and operating valve means for admitting fluid to the piston means for movement of the head and alternative means for admitting fluid to said piston means to urge said head in the direction of the movement produced by admission of fluid by the last-mentioned operating valve means; a common operator shiftable to and fro for actuating the aforesaid operating valve means, with actuating connections therefrom for opening the second operating valve means for admission after opening of the first and third operating valve means for admission and venting respectively, when said operator is shifted further and further toward one extreme of its movement, and for opening the second operating valve means for venting after opening of the first and third operating valve means for venting and admission,

respectively, when said operator is shifted fur ther and further toward the other extreme of its movement; and means for either connecting said alternative means to said piston means and shutting off connection of said third operating valve means thereto, or vice-verse.

9. In a press of the character described, the combination with a moving press head or platten and piston means for imparting to said head its working and return movements, and means for supplying working fluid under relatively high pressure for moving said head; of operating valve means for controlling the supply and venting of working fluid at a relative low rate to and from said piston means for the working and return movements of said head, operating valve means for controlling the admission and venting of working fluid at a relatively high rate to and from said piston means for the working and return movements of said head, and otherjoperating valve means for admitting. fluid to the piston means for the return movement of'saidv head, and venting it therefrom during the work ing movement; alternative means for constantly admitting fluid to-the piston means to urge 'said head continually-in the direction ofretum move with said last-mentioned operating valve means to control said supplemental valve means.

10. In a press of the character described, the combination with a moving press head or'platten and piston means for imparting to said head its working and return movements, and means ment; means for receiving and accumulating, at

relatively low pressure, fluid discharged from the piston means during the return movement of the head; supplemental valve means for controllingf' this accumulation, and for admittin'gfthe acc'umulated low pressure fluid to the piston'means for working movement of the headi ia common '50 verse movement operator shiftable to and fro for actuating said operating valve means, with actuating connections therefrom for successively opening the flrsi and second operating valve means for admission when said operator is shifted furth'er and further toward one extreme of its movement, and for successively opening the first and second operating valve means for venting when said operator is shifted further and further toward the other extreme of its movement: and selective means for determining whether fluid is constantly .ad-

mitted to the piston means by said alternative means, or admitted and vented by the last-mentioned operating valve means, and also coacting verse '5 movement 'said" reverse movement; sure reservoir with connection for receiving and accumulating, at relatively low pressure,

stantly admitting fluid to the piston means to urge said head continually in the direction of return movement; means for receiving and ac-.

cumulating, at relatively low pressure, fluid. discharged from turn movement of the head; supplemental valve means for controlling this accumulation, and for admitting the accumulated low pressure fluid to the piston means for working movementof the head; and selective. means for determining whether fluid is constantly admitted to the piston means by said alternative means, or admitted and vented by the last-mentioned operating valve means, and also coacting with said lastmentioned operating valve means to ontrol said supplemental valve means.

11. In a press of the character described, the

combination with a moving press head or platten and piston means for imparting to said head its working and return movements, and means for supplying working fluid under relatively high pressure for moving said head; of operating valve flmeans for admitting fluid to the piston means "for the movement 0! H said head one way. and venting it therefrom during the of said therefrom during the first-mentioned movement;

alternative means for admitting fluid to thep fi' 1 tonmeans to urge said head in the direction of a liquid and gas presdischarged from the piston means during said reofv accumulated fluid to the piston means for the first-mentioned movement of the head, with supplemental valve means for controlling this connection; and selective the piston means during the rereverse movementor said head; operating valve means for admitting fluid to the piston means for said re- I head, and venting it of the head, and for the return,

means for determining whether fluid is admitted to the piston means by said alternative means,

to control said supplemental

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