US2127324A - Prefill valve for hydraulic presses - Google Patents

Description

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' EQCANNON Filed Oct. 10, 1936 V PREFILL VALVE FOR HYDRAULIC PRESSES Aug. 16, 1938 E. CANNON 2,127,324,

PREFILL VALVE FOR HYDRAULIC PRESSES Filed Oct. 10, 1936 s Sheets-Sheet 3 j l r 1 l I l INVENTOR C'wrwwn/ ATTORNEYS Patented Aug. 16, 1938 r-a'riatrr o-Fncs 2,121,324 ranrm. vanvn roa HYDRAULIC masses Cannon, Rockville Centre, N. 2., assignor to E. W. Bliss Company, Brooklyn, N. Y.,.a corporation of Delaware Application mm: 10, 1030, sens inn. 105,005

' 19 Claims. (Cl, 121-38) This invention'relates to improvements in pre-' fill valves for permitting the rapid filling of the 'ram work chamber of a hydraulic press with oil, or other fluid prior to setting up high pressure therein, and is described and illustrated herein. as applied to such valves wherein means are provided for quickly advancing. the press ram into engagement with the work.

Heretofore the quick advance of the main ram in some hydraulic presses has been accomplished by the use of one or more auxiliary rams, operated under relatively low pressure. During' the advance of the main ram in such presses, and as a result of suction created thereby, fluid from a nearby reservoir is drawn through the preflll valve into the ram work chamber of the press, whereupon the prefill valve is closed to permit the setting up of pressure in said chamber suflicient to perform the desired work. For compactness and direct connection, both the preflll valve and a fluid tank have in many presses been mounted on the top of the press, co-axially with the ram chamber, the quick advance of the ram being accomplished by means independent of said ram. In other presses a rod or conduit extends axially within the ram to conduct fluid into a quick-advance chamber therein. and the preilll valve is mounted toward one side of the axis of the ram and is connected to the tank and the ram chamber by suitable pipe connections. My present invention embodies a combination of these. two arrangements, resulting in a more compact and highly efllcient structure which may be economically constructed and maintained.

My invention is disclosed and described herein as applied to a spring-opening type of valve which has certain advantages over a spring-closing type of valve. The latter type, if arranged to depend upon the suction in the ram work chamber to cause it to open and permitthe flow of liquid into said chamber as the ram advances, opens only to a very limited degree and, therefore, does not permit a free and rapid flow of liquid into the said chamber. Such spring-closing type valves, of course, may be and have been provided with auxiliary hydraulic chambers to cause them to open by hydraulic pressure, in which case additional pipes and auxiliary valves are necessary to control the movement of the preflll valve. It is obviously desirable, both from the standpoint of eihciency of operation and compactness of design, to minimize the piping employed in such presses.

An important object of my invention is the provision of a spring-opening type of preflll mit rapid filling of the ram valve which will not have the objectionable characteristics of the spring-closing type of valve as A further object of the invention is the provision of a compact arrangement of prefill valve,

. a tank, and a rod or conduit for conducting fluid into a quick-advance chamber in the ram, all' co-axially disposed relativelyto the ram 01 a press, such arrangement requiring a minimum of piping and yielding a maximum of eiiiciency.

A further object of the invention is the provision of means within the valve structure for by.-

passing pressure from a point at one side of the valve to the ram work chamber at the other side thereof, after the valve has been closed, thus additionally minimizing the piping that is necessary for operating a press.

The foregoing and other objects are accomplished by my invention as described and defined in the following specification and claims and as illustrated in the accompanying drawings, in which:---

Figure 1 is a vertical cross-section of a valve according to my invention.

Fig. 2 is a vertical cross section of a modified form of valve. I I

Fig. 3 is a horizontal section, looking upward, on the line 3-3 of Fig. 2.

Fig. 4 is a vertical cross-section of a still further modification of my invention.

Fig.5 is a horizontal section, looking upward, on the line 5-5 of Fig. 4.

Fig. 6 is a vertical cross-section of another bore ii to permit the passage of fluid therebetween. .The wall ofthis passage is formed by an annular valve seat i'l, fitted tightly within the the bore l2, extends between the latter and the casing Ii, and having a vertical seating surface cated in the drawings. wherein the upward movement or said element is limited by the head il,-and a closed position, wherein the down-- ward movement oi the valve element is limited by the valve seat ll; said valve element having a vertical seating suriace 2| and an oblique seating surface 22, which seating surfaces. respectively, cooperate with the seating surfaces ll and II of the valve seat l'| A compression spring 22 is disposed about a reduced lower portion of the valve element 20, and seats against the valve seat I! and a shoulder 24 on the valve element 2| to hold the latter in an open position. A tank 2| is suitably mounted upon the casing II and substantially surrounds the valve structure. One or more openings 2' are provided in the casing ll leading into a surge chamber 21 in the lower part of the bore l2 for permitting a tree flow or surge of fluid between the tank 2| and said chamber at substantially atmospheric pressure.

The bore l2 serves as a valve chamber comprising the surge chamber 21 and a valve-closing chamber 2| of inversely variable volumes, which vary with the reciprocation of the valve element therewithin. A port 20 opens into the valve-closing chamber 2' to permit the admission of fluid tnereinto under pressure to move the valve element to its closed position.

The bore It serves as a ram chamber comprising a ram work chamber 2| and a ram return chamber ll of inversely variable volumes, within which chambers a reciprocating ram ii is accurately fltted. This ram is somewhat elongated and substantially cylindrical in shape. An upper portion of the ram is of enlarged diameter and works within the said chambers between a raised position, as indicated in full lines in the drawing, and a lowered or advanced position, as indicated in broken lines. The remainder of the ram is of reduced diameter andextends downwardly beyond the casing ii to engage the material being worked upon by the press, a ring 32 being flxed within the lower end oi said casing and about the ram to prevent leakage of fluid from the ram return chamber ll.

The interior of the ram II is hollowed to form a'cylindrical quick-advance chamber ll therewithin. An elongated rod 24 is flxed to the head it by a nut II and extends downwardly centrally through the valve-closing chamber 22, the surge chamber 21, the passage II, and the ram work chamber 30. The said rod extends through a bore It in the valve element 2| and a bore 21 in the upper portion of the ram Ii, and terminates within the quick-advance chamber 22. The rod 34 has an axial passage 3. extending throughout its length and opening into the quick-advance chamber 22 to permit the admission of fluid thereinto under suflicient pressure to quickly advance the ram 3i into engagement with the material being worked.

A port 30" is provided to permit the exhaustion of fluid from the ram return chamber 20' on the advance stroke of the ramand to admit fluid into and chamber to return the ram to a raised posi- Itwill beseen that after the ramhas been lowered or advanced into engagement with the material being worked, by the admission of fluid into the quick-advance chamber It, and the valve element 2| has been moved to a closed position, the ram work chamber It will contain fluid at substantially atmospheric pressure, and the fluid pressure in said chamber must be increased to aromas impose sufllcient pressure upon the ram to enable it to perform the desired work. A source of fluid pressure could, of course, be independently connected to saidchamber, necessitating a separate pipe connection for that purpose. According to my invention, however, the use of such separate connections may be avoided, and to this end I employ a by-pass arrangement whereby the port 20, which admits fluid into the valve-closing chamber 28, also serves for establishing suitable fluid pressure in the ram work chamber 20.

A bore 2! is provided extending within the wall of the casing II from a point opposite the valveclosing chamber 2| to a point near the ram work chamber ll, an opening I connecting said bore with said valve-closing chamber and a passage 4| connecting said bore with the ram work chamber. A check valve 42 is arranged to be held closed across the opening III by a compression spring 48 co-acting with a screw plug 44 which also serves as a guide for said check valve. The compression of the spring 43 is such that the check valve 42 may not open until the pressure within the valve-closing chamber 2| exceeds the pressure required to move the valve element 20 to a closed position.

The cycle of operation commences with the various parts in the positions shown in full lines in the drawings and with fluid under substantially atmospheric pressure in the tank and in all the various chambers and passages referred to, except in the ram return chamber III wherein sufllcient pressure is present to hold the ram ii in a raised position.

Fluid is admitted under moderate pressure into the quick-advance cylinder 33 through the pas- ,sage II in the rod 24, the ram return cylinder 3., meanwhile, being permitted to exhaust through the port This causes the ram Ii to descend into engagement with the material being worked. The descent of the ram causes fluid from the tank 25 to be drawn or sucked through the openings 20 into the surge chamber 21 and thence through the passage It into the ram work chamber 30,

Fluid is then admitted under relatively high pressure through the port 29 into the valve-closing chamber 28, causing the valve element 2| to descend to a closed position. The continued introduction of pressure through the port 22 sets up pressure in the valve-closing chamber 28 suflicient to open the check valve 42 and establish communication between the valve-closing chamber 2| and the ram work chamber 30 through the opening III, the bore 39, and the passage 4|, and thus introduces a suitable working pressure into the ram work chamber 30. The pressure introduced into the said ram work chamber through the port 29 may be raised to the extent necessary to permit the ram to fully perform its desired work. At this stage of the cycle the ram 3| is in substantially, the position indicated in broken lines in the drawings.

It will be seen that after the check valve 42 opens, a substantially uniform fluid pressure is present in both the valve-closing chamber 28 and v the ram work chamber 20. As the upper surface of the valve element 20, which is subjected to downward pressure, is of greater area than the lower surface thereof, which is subjected to upward pressure, it is obvious that there is a predominant downward force exerted upon the valve element 20 which operates to hold said element in a closed position while working pressure is maintained in the ram work chamber, it being by simultaneously releasing the p areas I apparent that the excess downward force must be sufiicient'to overcome in addition the expansive force of the spring 23. I L The return stroke of the ram is accomplislzleld n e valve-closing chamber 28 and the quic .-advance chamber It and introducing fluid under pressure into the ram return chamber 30a, thereby permitting the exhaustion of the chambers 2| and 33, allowing the spring 23 to raise the valve element 20, and forcing the ram 3i upwardly to its uppermost position and permitting the fluid in the ram .work chamber 30 to surge upwardly and outwardly through the passage IS, the surge chamber 21, and the openings 26 into the tank 25, thereby completing the cycle.

It is highly desirable to provide means whereby, on the return stroke of the ram II, as aforesaid, the pressure within the .ram work cylinder 30 may be gradually relieved and reduced to substantially atmospheric pressure, as otherwise the instantaneous release of such pressure upon the unseating of the valve element '20, combined with the action of the spring 23, gives rise to severe shock and to detrimental structural stresses in the press. Means to this end are disclosed and claimed in my co-pending application, Serial No. 111,790, filed Nov. 20, 1936. As disclosed herein, these means comprise a plurality of vertical grooves of various lengths in the lower part of the valve element 20. These grooves are disposed about and interrupt the vertical seating surface II of the said valve element and extend to the lower edge of said surface. As the valve element 20 rises on the return stroke of the press, the longer grooves 45 and then the shorter grooves 45, in succession. extend beyond the upper edge of the vertical seating surface ll of the valveseat l'|,-thus establishing a relatively gradual fluid connection between the tank 25 and the ram work chamber 30 and permitting a relatively gradual reduction of the pressure within the latter, thereby eliminating any objectionable shock and structural stresses. This operation, although taking place progressively to release the pressure, takes place as a practical proposition in a fraction of a second.

The embodiments of Figs. 2 and 4 differ from They diifer also from 1 are sufliciently large to by-pass fluid under pressure, they, nevertheless, are sufliciently small to frictionally retard the passage of fluid therethrough and to permit the accumulation of pressure in the valve-closing chamber 28 to cause the valve element 20 to move downwardly to a closed position as a result of the introduction of .fl'uid into said chamber through the port 29.

Once the valve element 20 reaches its closed posi-' tion, the greater total force upon the upper surface thereof, as compared to the total force upon the lower surface thereof, operates'to hold the said valve element in a closed position against the compression of the spring 23.

It is obvious that larger or greater numbers of by-pass grooves 48 may be provided, the design of the valve in this respect being governed in a measure by the viscosity of the fluid to be used. In any event, such'grooves must not be large enough in the aggregate to pass fluid with sufficient rapidity to prevent the accumulation of pressure in the chamber 20 upon the initial introduction of fluid into said chamber through the inlet 28, as under such conditions the valve would' prevented from closing.

The y-passing means illustrated in Fig. 4 comprise amannular passage 49 formed by the enlargement of the lower portion of the bore 38 in the valve element 20 and extending from the bottom to a point near the'top of said valve element. Fluid connection is provided between the passage 49 and the valve-closing chamber 28 by 'an eccentrically-disposed axial passage 50 in the valve element 20 extending from the top thereof to a point therein opposite the upper end of the annular passage 48, and by an opening II connecting the latter with the passage 49. A check valve 52 is guided within a bore 53 at the lower end of the said axial passage and urged by a compression spring 54 within the bore 63 toward a closing position across the lower end of a tubular threaded seat 56 which is screwed into the upper end of the axial passage 50.

The by-passing means illustrated in Figs. 1 and 4 operate similarly, but diifer principally in that in the former the by-pass check valve and passages are in the valve casing, while in the latter they are in the slide valve. Although the accompanying drawings show only one by-pass. check valve in each embodiment, it is obvious that two or more such valves may be utilized, if desired.

Fig. 6 illustrates by-passing means which are very similar to and function similarly to the bypassing means shown in Fig. 1, the principal differences being that the by-pass fluid connection between the valve-closing chamber 28 and the ram work chamber 30 comprises pipe connections I9 disposed outside of the valve structure, instead of the bore 39, opening 40, and passage 4| shown in Fig. 1 in the valve casing, and that a check valve 56 of modified form is employed for the same purpose as the check valve disclosed in Fig. 1.

Suitable pumping and valving means (not shown) are provided in the several modifications to-time and otherwise control the admission of fluid into the several chambers and the exhaustion thereof to achieve the desired cycle of operation and the necessary fluid pressures.

Myinvention has been described herein and illustrated in the accompanying drawings, solely for illustrative purposes, as employed in a vertical press with a descending ram, but it may obviously be employed in a horizontal press or in a vertical press with an ascending ram or in presses disposed at any angle. Its employment in such various presses and in various modifications may obviously be resorted to without departing from the spirit of the invention.

What I'claim is:

1. The combination with a hydraulic press having. a ram chamber, a ram adapted to reciprocate within said chamber, and a fixed rod extending within a bore in the ram, of a prefill valve comprising a casing within which the said flxed rod extends, a surge chamber in said casing communicating withthe ramchamber, an open.- ing in said casing arranged to permit the flow of fluid into said surge chamber, a valve element slidably mounted upon said flxed rod within said casing, and means for reciprocating said valve element within said surge chamber to control the flow oi fluid between the latter and the ram chamber, the fixed rod being fixedly connected to said casing.

2. The combination according to claim 1 wherein the said ram, fixed rod, and valve element all have a common axis 01' symmetry.

3. The combination according to claim 1 further characterized in having a tank for holding fluid, said preflll valve being disposed substantially within said tank in a position to be immersed in fluid therein whereby to permit the ready flow thereof between said valve and said tank.

4. The combination according to claim 1 further characterized in having an interior hydraulic chamber in the ram and the said fixed rod having an axial passage opening into said.

interior hydraulic chamber and being adapted to conduct fluid thereinto to advance the ram.

5. The combination with a hydraulic press having a ram chamber, a ram adapted to reciprocate within said chamber, and a fixed rod extending within a bore in the ram, of a prefill valve comprising a casing, an annular valve chamber, within which the said fixed rod extends, having an opening in the wall thereof to permit the passage of fluid thereinto, an annular communicating passage between said valve chamber and the ram chamber, an annular valve element within said valve chamber extending around and adapted to slide upon said rod, and means for sliding the valve element between an, open position and a closed position wherein a portion of said element extends across and closes said passage, the flxed rod being fixedly connected to said casing.

6. The combination in a hydraulic press of a ram chamber. a valve-closing chamber, a surge chamber, and a communicating passage between the latter and the ram chamber, all having a common axis of. symmetry, a reciprocating ram adapted to hydraulically work within the ram chamber, a reciprocating slide valve element adapted to hydraulically work within the valveclosing chamber and the surge chamber and having a seating portion adapted to seat across and close said passage when in a closed position, a fixed rod extending centrally through the said valve element and communicating passage and into the reciprocating ram, an opening in the wall of said surge chamber to permit the admission oi fluid thereinto, and spring means for urging the said valve element toward an open position wherein fluid may flow freely through said passage, the valve-closing chamber being adapted to receive fluid thereinto under pressure to urge the valve element toward a closed position against the force of said spring means, the said press having a casing to which the fixed rod is fixedly connected.

'7. The combination, in a hydraulic press, of a ram chamber, a reciprocating valve element adapted when in a closed position to substantially close the said ram chamber whereby to permit establishment of working pressure therein, a valve-closing chamber adapted to hydraulically move said valve element to its closed position, and means for passing fluid from the latter chamber to the ram chamber to establish working pressure therein, said means comprising a continuously open passage connecting the two said chambers, the said passage being of such restricted area that, as fluid passes therethrough open communication therewith, a casing, a valveclosing chamber, a reciprocating ram movable within the ram chamber, a reciprocating valve element movable within the valve-closing chamber and the surge chamber and having an inner end adapted to substantially close the surge chamber and ram chamber against communication when said valve element is in a closed position and having an outer end adapted to receive hydraulic pressure to urge the valve element to a closed position, and means for transmitting fluid pressure between the valve-closing chamber and the ram chamber, and being provided which is fixed to said casing and extends through the said said valve element and into said reciprocating ram.

10. The combination according to claim 9, the said means for transmitting fluid pressure comprising an interior longitudinal groove in the valve element adjacent to the fixed rod and forming, with the latter, a passage for transmitting fluid pressure between the valve-closing chamber and the ram chamber.

11. The combination according to claim 9, the said means for transmitting fluid pressure comprising an annular passage extending around the fixed rod at one end of the valve element and a duct extending from said passage to the other end of the valve element.

12. The combination, in a hydraulic press, of a ram chamber, a surge chamber normally in open communication therewith, a casing, a valve-closing chamber, a reciprocating ram movable within the ram chamber, a reciprocating valve element movable within the valve-closing chamber and the surge chamber and having an inner end adapted to substantially close the surge chamber and ram chamber against communication when said valve element is in a closed position and having an outer end, adapted to receive hydraulic pressure to urge the valve element to a ,closed position, and means for transmitting fluid pressure between the valve-closing chamber and the ram chamber, the said casing substantially surrounding all said chambers, and the said means comprising a passage in said casing adapted to transmit fluid pressure between the valve-closing chamber and the ram chamber.

13. The combination according to claim 12, further characterized in having a valve adapted to permit transmission of pressure between the valve-closing chamber and the ram chamber only when the pressure in the valve-closing chamber is greater than required to move the valve element to a closed position.

14. The combination, in a hydraulic press, of a ram chamber, a surge chamber normally in open communication therewith, a casing, a valve-closing chamber, a reciprocating ram movable within the ram chamber, a reciprocating valve element movable within the valve-closing chamber and the surge chamber and having an inner end adapted to substantially close the surge chamber and ram chamber against communication when said valve element is in a closed position and havment to a closed position.

ing an outer end adapted to receive hydraulic pressure to urge the valve element to a closed and the ram chamber.

15. The combination according to claim 14, further characterized in having a valve adapted to permit transmission of pressure, between the valve-closing chamber and the ram chamber only when the pressure in the valve-closing chamber is greater than required to move the valve ele- 16. The combination according to claim 9, the said means-for transmitting fluid pressure comprising an interior longitudinal passage in the valve element adjacent to and partly defined by the fixed rod, the said passage being of such restricted area that, as fluid from the valve-closing chamber passes therethrough, sufllcient back pressure is created in the valve-closing chamber to close the valve and permit the establishment of working pressure in the ram chamber.

1'7. The combination according toclaim 9, further including spring means coacting with the reciprocating valve element whereby to urge the latter toward an open position, the said means for transmitting fluid pressure comprising an interior longitudinal passage in the valve element adjacent to and partly defined by the fixed rod, said passage being of such restricted area that, as fluid from the valve-closing chamber passes therethrough, sumcient back pressure is created in the valve-closing chamber to close the valve element against the action of said spring means. 7

18. The combination according to claim 'I, further including spring means coacting with the reciprocating valve element whereby to urge the latter toward an open position, the back pressure createdin the valve-closing chamber being suiflcient to move the said valve element to its closed position against the action of said spring means.

19. The combination according to claim '7; fur;- ther including spring-means coacting withthe reciprocating valve element whereby to urge the latter toward an open position, the back pressure created in the valve-closing chamber being sufficient to move the said valve element to its closed position against the action of said spring means, the said passage being in the said valve element and afiording fluid connection between the two said chambers when the said element is in closedposition.

EARL CANNON.

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