US1892568A - Surge valve for hydraulic presses or the like - Google Patents

Description

Dec. 27, 1932. w. ERNiT 1,892,568

l SURGE VALVE FOR HYDRAULIC PRESSES OR THE LIKE Filed Dec. l2, 1950 l 2 Sheets-Sheet l Snventor Walzefz'fw,

Gttornegs.

Dec. 27, 1932. w. ERNST SURGE VALVE FOR HYDRAULIC PRESSES OR THE LIKE Filed Dec. 12, 1950 2 Sheets-5heet 2 Patented Dec. 27, 1932 UNITED STATES PATENT OFFICE WALTER ERNST, OF MOUNT GILEAD, OHIO, ASSIGNOR TO THE HYDRAULIC PRESS MANUFACTURING COMPANY, OF MOUNT GILEAD, OHIO SURGE 'VALVE FOR HYDRAULIC PRESSES OR THE LIKE Application filed December 12, 1930. Serial No. 501,994.

This invention relates to improvements in surge valvesfor hydraulic presses or the like.

ln certain kinds of hydraulic machinery which include power cylinders into whic fluid under pressure is introduced for causing a ram to move a platen, die, punch, or the like towards a table supporting material to be worked upon, it is usual to so arrange the press operating circuit that the initial part of a pressing or working stroke is performed by the gravitational descent of the rain and platen, or to provide auxiliary or booster cylinders for advancing the main ram toward the work during the initial part of the working stroke. Such booster cylinders are of lesser diameter than the main work cylinder and the fiuid delivered under pressure from the pump therefore acts to move the booster ram and the main ram downwardly more rapidly than would be the case if the fluid were directed to the larger main cylinder' during the entire Working stroke. During initial part of the working stroke,

' when the fiuid from the pump is being delivered to the booster cylinders, or, in presses in which no booster cylinders are provided, when the rain and platen are descending gravitationally, it is necessary that the main cylinder' be placed in communicationl with a surge tank in order that the main cylinder may be prefilled bv a gravity iow of fluid from the tank, so that during the latter part of the work stroke when the pump discharge is directed to the main cylinder, the latter will be full of fluid. Various kinds of surge valves for controlling the communication between the surge tank and the main cylinders of presses of this kind have been heretofore used and within limits have functioned satisfactor-ily. One difliculty or defect in valves of this kind previously employed is that they have been so constructed and so arranged relative to the other parts of the press-operating circuit as to result in there being a considerable resistance to the gravity prefilling action, this resistance being due to pipe connections interposed between the surge tank and the valve and between the valve and the cylinder, to bends ingsuch pipe connections,

and to inefficient arrangement of the parts and passages of the valves.

An object of the present invention is to provide a surge valve so constructed and adapted to be so arranged with relation to a surge tank and the main cylinder of a hydraulic press or the like as to efiiciently provide for, and control communication between the tank and cylinder and affording a minimum of resistance to the free flow of fluid therebetween. Other objects will become apparent from a reading of the following description of a practical embodiment of the invention, the appended claims, and the accompanying ,drawings in which:

Figure l is a diagrammatic view of a press-operating circuit including a surge valve embodying the invention;

Figure 2 is a view in front elevation of a hydraulic press forming part of the circuit;

Figure 3 is a central vertical sectional view of a surge valve embodying the invention;

Figure 4 is a horizontal sectional view taken on the line 4--4 of Figure 3, and

Figure 5 is a horizontal sectional-view taken on the line 5-5 of Figure 3.

The surge valve illustrated herein as embodying the present invention may be. used in connection with various kinds of presses and press-operating circuits, and for purposes of illustration is shown las formino' a part of a hydraulic circuit including a, T1 draulic press A of the downward pressure type adapted to be operated by means of a reversible flow circuit including a radial reversible pump B of a well-known kind and a surge tank C mounted on top of the press.V

The press A includes a base l, a press head 2 connected to the base by strain rods 3 and a platen 4 mounted for reciprocatory movements on the strain rods. A main ram 5 is connected to the platen and extends into a main cylinder 6 while booster rams 7 also connected to the platen extend into booster cylinders 8. Push back rams 9, also connected to the platen, extend downwardly into push back cylinders 10. The surge valve embodying the present invention and generally designated D is Amounted inthe top of the main cylinder 6 and is adapted to afford comthe press operating circuit and associated valve mechanism, which is to follow, may -be more readily understood it may here be stated in general that when a pressing or working stroke is to be performed fluid is first introduced into the booster cylinders 8, this fluid then acting upon the booster rams to move the platen downwardly, .which will also efl'ect a downward movement of the main ram 5 and the consequent vacating of the main cylinder bythe ram 5. As will be later described, during this period of operation the surge valve D opens to permit a gravity prefill of the main cylinder from the surge tank. When the platen encounters the work, fluid under pressure delivered by the pump is directed to the main cylinder as well as to the booster cylinders. This fluid entering the main cylinder under high pressure is active to close the surge valve, that is, to close communication between the main cylinder and the surge tank after which the pressing operation will be performed by high pressure fluid in the main and booster cylinders. When this operation has been completed fluid under pump pressure is directed to the push back cylinders 10, thus moving the platen and associated parts upwardly. During such movement fluid is exhausted from the main cylinder to the tank by means of the surge valve, and from the booster cylinders to the tank and pump.

For conduct-ing fluid under pressure to the several cylinders of the press to effect the above-described sequence of platen movements, hydraulic connections and suitable valve mechanism are connected between the pump, the tank and the press cylinders. .In the circuit illustrated these connections 1nclude a pipe line 12 which connects one s ide of the pump to a chamber 13 of a valve casing 14 of a valve mechanism generally designated E, and a pipe line 15 which connects the other side of the pump to a valve chamber 16 also formed in the casing 14. A pipe 17 affords communication between the surge tank and a chamber 17a in the valve casing 14, the

chamber 17a being disposed between the chambers 13 and 16 and being separated therefrom by partitions 18 and 19 respectively. A valve stem 20 extends through openings 20a and 21'in the partitions 18 and 19 and is provided at its ends with heads -22 and 23 which are adapted to close the openings 20a and 21 respectively.

The casing 14 is formed with a depending casing portion 24 which includes a chamber 25 which is adapted to communicate with the chamber 13 by means of a passage 26. This communication is controlled by a valve head 27 formed on a valve stem 28 which extends through and is mounted for sliding movements in the valve depending casing portion. The lower end of the stem 28 extends into a recess 29 in a l separate casing 30 having threaded connection with the depending portion 24. A spring 3l is interposed between a head 32 on the lower end of the stem 28 and a head 33 on the inner end of an adjusting screw 34 which extends through and has threaded connection with -a cap 35 screwed onto the lower end of the depending casing 24. A pipe 26 affords constant communication lietwccn the surge tank and the valve chamber 25. A branch pipe 37 leads from the pipe line 12 to the booster cylinders; and a branch pipe 38 leads directly from the pipe line 15 to the push back cylinders.

The press and press-operating circuit described above are in general shown, described and claimed in my prior U. S. Patent 1,672,561 issued June 5, 1928; and it is to be understood that the description of this circuit lias been included in the present disclosure only in order that the operation of the surge valve forming the subject matter of the present invention and its arrangement relative to other parts of the press and circuit may be readily understood.

The surge valve D constructed and arranged in accordance with the invention includes a cylindrical valve casing 39 positioned in an opening 40 in the top of the cylinder 6 and extending downwardly into the cylinder, the casing being provided with a peripheral flange 41 positioned in a seat 42 on the top of the cylinder. The valve casing is clamped in place by means of a clamping ring 43 which forms part of a separate casing member 44 disposed directly above the valve casing 39 and which is drawn downwardly against the flange 41 by means cf suitable securing means such as bolts 45.

The valve casing 39 is formed with a bore 46, the upper end portion of which is of reduced diameter. This bore faces directly up toward the surge tank and communicates directly therewith by means of a plurality of openings 47 in the separate casing member 44. The bore communicates directly with the main cylinder by means of a plurality of radial passages 48 extending through the casing and-lying in a common horizontal plane disposed substantially at the vertical center of the casing 39. It will be seen that by arranging the valve casing to communicate directly with the main cylinder and tank, the use of connecting piping is r'ndered unnecessary ltki and efficient prefilling and exhausting of the cylinder's provided for. It is not necessary t at the valve casing be disposed within an opening in a cylinder wall wjhich forms a partition between the cylinder chamber and surge tank but it is important that the casing be disposed between the cylinder chamber and tank and so arranged that the ends of the casing open substantlally directly into the tank and cylinder respectively without the use of connecting piping. A valve element 49 is mounted for vertical sliding movements within the bore and is provided with a plurality of vertically extending ribs or wings 50 which cooperate with the reduced upper portion of the bore for guiding the valve element. This element is formed with a seat engaging surface 51 which is tapered outwardly and downwardly and which is adapted to seat upon a peripheral seat 52 formed in the bore 46, the seat being similarly tapered outwardly and downwardly, and being disposed above and immediately adjacent to the radial passages 48. Means are provided for biasing the valve element upwardly to closed position and in the form shown the lower part of the valve element 49 is hollow and accommodates a biasing spring 53 interposed between a plate 54 secured to the lower end of the casing 39 and a spring seat 55 formed in the hollow part of the valve element. The plate 54 is perforate as at 56 and is provided with aspring centering rib 57. The spring 53 1s just strong enough to maintain the valve element in its upper position against its own weight and is readily yieldable to permit the element to move downwardly when the pressure on the lower side thereof is slightly less than that on the top side.

In operation, when the platen and main and booster rams are being moved downwardly under the action of high pressure fluid directed to the booster cylinders only, the vacating of the main cylinder by the main ram will tend to create a suction in this cylinder. As soon as this takes place the statlc pressure due to the head of fluid in the surge tank will move the valve element 49` downwardly and fluid will flow downwardly from the surge tank through the openings 47, the spaces between the ribs 50 and thence through the radial passages 48 and into the cylinder. It will be observed that with the exception of the change 'from downward to outward flow at the plane of the radial passages 48,

the fluid has a direct and unobstructed path over which to travel in passing from the surge tank to the cylinder so that a minimum of resistance to fluid flow is offered. The drag on the descent of the platen and rams usually due to restricted flow is therefore reduced to a minimum and more efficient operation of the press is made possible. It will also be vobserved that due to the particular arrangement of the tapered valve engaging surface 52, the fluid is deflected smoothly outward `through the passages 48 so that no seriously abrupt changes in the direction of fluid flow take place. By locating theI surge valve in tne opening in the cylinder, the piping usually necessary to connect the tank, the valve and the cylinder is dispensed with and losses heretofore due to frictional resistance to the pretilling of the main cylinder are further reduced. I'

In certain kinds of press operating circuits, such as'that illustrated in the accompanying drawings, it is Vnecessary that the surge valve be opened when fluid is introduced into the push back cylinders to effect a return movement of the platen. This is necessary in order to provide for the expelling from the cylinder of the fluid remaining therein at the end of a working stroke. In accordance with one feature of the present'invention I provide a pressure actuated plunger 58 mounted for vertical sliding movements in a bushing 59 in the separate casing member 44, the upper end of the plunger extending into a pressure chamber 60 closed at its upper end by means of a plate 61. A spring 62 is interposed between a head 63 on the upper end ofthe plunger 58 and the top face of the bushing, this spring serving to normally maintain the plunger out of contact with the top of the movable valve element 49. A pipe 64 afl'ords constant communication between the pipe 15 and the chamber 60 and, as will be later described, when fluid is introduced into the booster cylinders, fluid under pump pressure will also be introduced into the chamber 60 which will result in the plungers being moved downwardly into engagement with the valve element 49 for moving the latter downwardly.

In order that the function of the surge valve and its relation to the various other parts of the circuit may be readily understood, a complete operating cycle of the press provided with this valve will be briefly set forth. It will be assumed that the platen is in its upper position and that the parts are in the relative positions shown in the drawings. When it is desired to produce a working stroke, the pump control device 1 1 is set to cause the pump to deliver fluid under pressure through the pipe line 1.2. rlhis fluid will pass through the pipe line 37 and into the booster cylinders and will act on the booster rams to move the plat-en and main ram downwardly. During this part of the downward stroke there is little resistance to movement of the platen so that fluid will be trapped in the valve chamber 13 by means of the valve head 27 held closed by the spring 31. While the ram is descending the suction created in the main cylinder will result in the surge valves being opened in the manner already described and fre-e unobstructed prefilling of the main cylinder will take place.

When the platen encounters resistance to its downward movement, pressure will build up in the booster cylinders, in the pipe lines 27 and 12, and in the chamber 13 until a predetermined pressure has been attained, at which time the fluid pressure acting on the valve head 2T will move the latter downwardly and admit fluid under pump pressure directly to the main cylinder by means of the pipe line 36. The increased fluid pressure now active in the main cylinder will close the surge valve whichwill then maintain an effective seal between, the main cylinder and the surge tank, and the pressing operation will be completed with fluid under pressure being delivered to both the main and booster cylinders. During the downward movement of the ram just described the pump will take in fluid partly from the push back cylinders l()l by means of the pipes 38 and l5, and partly from the surge tank by means of the pipe 17 the valve chamber 17, the valve chamber 16, and the pipe 15. When the pressing operation has been completed the pump control device will be set to reverse the direction of discharge from the pump so that fluid will be directed under pressure through the pipe line 15, the pressure fluid entering the chamber 16 and moving the valve 20 to the left. Fluid will then be delivered by the pump to the push back' cylinders 10 by means of the pipe 38 and will move the platen and rams upwardly. When the pump has been reversed to elect this upward movement of the platen, fluid under pressure in the pipe line 15 will act through the pipe 64 and in the chamber 6() to move the plunger 58 downwardly at which time the plunger will engage and move downwardly the valve element 49 thus opening the surge valve and placing the main cylinder in communication with the surge tank. The platen will then continue to ascend until its uppermost position has been reached at which time the pump control device may be set either to reverse the pump and to effect another pressing operation or to bring the platen to rest.

It is obvious that the surge -valve here shown and described is not limited in application to use in connection with presses having separate booster and push back cylinders; and that the valve may be used to advantage in connection with all hydraulic presses vor the like in which a pressure cylinder is preilled by a gravity flow from a surge tank, for example in presses having no booster cylinders and in which the prefill of the cylinder takes place during gravitational dev scent of the ram and platen.

I claim:

1. In a hydraulic press or the like, the combination with a. cylinder having an o ening in its top; of a surge tank-supporte directly above said cylinder; a ram mounted for reciprocation in said cylinder, movement of the ram during a part of a workin stroke creating suction in said cylinder; a va ve casing mounted in the o ening in said cylinder and having a vertica ly extending bore the upper end of which faces and opens into said surge tank, said valve casing being rovided with a plurality of radially exten ing passages communicating with said bore and opening directly into the interior of said cylinder, and with a circular valve seat formed in said bore and located adjacent to and above said radial passages, said seat being tapered downwardly and outwardly towards said passages; a spring pressed valve element mounted for .vertical movements in said bore and being provided with a seat-engaging surface tapered downwardly and outwardly whereby Huid in passing downwardly through said bore, will be smoothly deflected outwardly towards and through said radial passages, said valve being ada ted to be opened by suction in said cylin er; a pressure chamber disposed within said surge tank and above said valve element; and a pressure responsive plunger mounted in said pressure chamber and bein adapted to be actuated by fluid pressure or moving said Valve element to its open position against the urge of said spring during a return stroke of said ram.

2. In a hydraulic press or the like, the combination with a cylinder having an opening in itsA top; of a surge tank supported on top of said cylinder; a ram mounted for reciprocation in said cylinder, movement of the ram during a part of a working stroke creating suction in said cylinder; a valve casing mounted in the opening in said cylinder; a

der, a valve element mounted for verticalv movements in said valve casing for controlling communication between said tank and said cylinder; a spring mounted below said valve element and cooperating therewith for urging the latter upwardly to close said communication and being yieldable to permit openin of said valve by suction in said cylinder uring a working stroke; and means including a pressure responsive plunger mounted in said separate casing member and directly above said valve element for moving said element downwardly to open said communication during a return stroke of said ram.

3. In a hydraulic motor for presses or the like, the combination of a motor cylinder; a surge tank mounted on top of the cylinder, the top of said cylinder being provided with an opening; a ram mounted for reciprocation in said cylinder, movement of the ram during part of a working stroke being adapted to create suction in the cylinder; a valve casing mounted in the openin in said cylinder and having a bore adapte to provide communication between the surge tank and cylinder; a pressure casing member positioned within said surge tank and in axial alignment with said valve casing; a valve element mounted for reciprocatory movements in said valve casing or controllingcommunication between said tank and cylinder; a spring seat on the inner end of said valvecasing; a spring interposed between said seat and said movable element for urgingthe latter towards its closed position and being yieldable to permit opening of said valve by suction in said cylinder during a working stroke; and a pressure re sponsive lunger mounted in said pressure casing an being adapted to be actuated by Huid pressure for moving said valve element to its o en position against the urgeof said spring lduring a return stroke of said ram.

4. In a hydraulic motor for presses or the like, the combination of a ram advancing cylinder-and a ram returning cylinder; a surge tank mounted on top of the ram advancing cylinder, the Atop of said ram advancing cylinder being provided with an opening; ram mea-ns mounted for reciprocation in said cylinders, movement of the ram means during part of a working stroke being adapted to create suction in the ram advancing cylinder; a valve casing mounted in the opening in said ram advancing cylinder and having a bore adapted to provide communication between the surge tank-and said cylinder; a valve element mounted for reciprocatory movements in said valve. casing for con` trolling communication between said tank and cylinder;`a spring engaging said movable valve element for urgingthe latter to'- wards its closed position and being yieldable to permit opening of said valve by suction in said cylinder during a working stroke; and means associated with said valve element and being responsive to pressure in said ram returning cylinder for moving said valve element to its open position against the urge of said spring during a return stroke of said ram.

l5. In a hydraulic motor Afor presses or the like, the combination of a ram advancing cyl inder and a ram returning cylinder; a surge tank mounted above the ram advancing cylinder, ram means mounted for reciprocation in said cylinders, movement of the ram means during part of a working stroke being adapted to create suction in the ram advancing cylinder; a valve casing interposed between said ram advancing cylinder and said surge tank and having a vertical bore communicating directly with both said tank and cylinder; a valve element mounted for reciprocatory movements in said vertical bore for con- Vof said spring during a return stroke of said lram.

6. In a hydraulic motor for presses or the like, the combination of a ram advancing cylinder and a rain returning cylinder; a surge tank mounted above the ram advancing cylinder, ram means mounted for reciprocation in said cylinders, during part of a working stroke being adapt- 1 s5 movement of the ram means ed to create suction in the ram advancing e cylinder; a valve Casin interposed between said ram advancing cylinder and said surge tank and having a vertical borecommunicat ing directly with both said tank and cylinder; a valve element mounted for reciprocatory1 movements in said vertical bore for contro ling communication between said tank and c linder; biasing means connected to said mova le valve element for urging the latter upwardly to closed position, said biasing means exerting suiiicfent pressure on said valve to support the latter against the action of gravity but being yieldable to permit opening of said valve by suction in said cylinder during a working stroke; and means associated with said valve element and being responsive to pressure in said ram returning. cylinder for .movin said valve element to its open position against the urge of said biasing means during a return stroke of said ram.

n testimony whereof, I have hereunto

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