US2489069A

US2489069A - Hydraulic apparatus

Info

Publication number: US2489069A
Application number: US652937A
Authority: US
Inventors: Cecil E Adams; Ellis H Born
Original assignee: Denison Engineering Co
Current assignee: Denison Engineering Co
Priority date: 1946-03-08
Filing date: 1946-03-08
Publication date: 1949-11-22
Anticipated expiration: 1966-11-22

Description

Nov. 22, 1949 c. E. ADAMS E AL HYDRAULIQ APPARATUS 2 Sheets-Sheet .1

I I INVENZ 'ORJ Ce c131 E.Adorns I Ellis I-LBorn 57 @M 5% Filed March 8, 1946 Nov. 22, 1949 c. ADAMS ET AL 2,489,069

HYDRAULIC APPARATUS Filed March 8, l9 46 2 Sheets-Sheet 2 V INVENTORS Cecil EAdums Ellis HJBorn Patented Nov. 22, 1949 HYDRAULIC APPARATUS Cecil E. Adams and Ellis H. Born, Columbus, Ohio, assignors to Ihe Denison Engineering Company, Columbus, Ohio Application March 8, 1946, Serial No. 652,937

Claims.

This invention relates to hydraulic apparatus and is particularly directed to apparatus for forming articles or objects by hydraulic pressure.

An object of this invention is to provide a, hy-

draulic press having a forming ram and a second ram operable in conjunction with the forming ram to knock out or eject the formed pieces from dies or similar tools used with the forming ram.

Another object of the invention is to provide a press having a hydraulic ram operating unit, a hydraulically operated unit for a knock out ram and a hydraulic circuit for controlling the operation of the units to secure a particular sequence of operations of the rams.

A further object is to provide a ram-operating unit of particular construction which will function, when the ram is moved in a certain direction, to supply auxiliary operating fluid to another unit, the construction being such that when the latter unit no longer needs the auxiliary operating fluid, the supply will be discontinued.

A still further object is to so construct the ram operating unit, mentioned in the preceding paragraph, and arrange the hydraulic circuit incorporating the unit and a knock out cylinder, or other power unit, that when the former reaches a certain stage of operation the latter will move or return to a predetermined position or stage of operation.

Another object is to provide the hydraulic system incorporating the various ram operating units with a valve for the selective operation of certain of the ram operating units in a predetermined manner.

An object of the invention also is to provide a press having a pressing-ram operating unit including piston cylinders of different sizes and pistons disposed in the cylinders and connected for movement in unison, the total of the areas of the pistons being effective when moving in one direction, the area of one piston being effective when the pistons are moving in the opposite direction to transmit at least part of the fluid used in the pressing operation, to an ejecting device, the difierence in areas of the pistons providing for a differential in the rate of travel of or the distance traveled by the pressing ram on its return stroke and the distance moved by the ejecting device.

Another object is to provide a hydraulic circuit for a pressing mechanism of the type having a pressing ram and a knock out ram, which may cause the knock out ram to move at a different rate of speed when the pressing ram has reached a predetermined point in its travel, the circuit being provided with mechanism to permit the selective return of the knock out ram to inactive position either manually or otherwise.

It is an object of this invention to provide hydraulic pressing mechanism having a, pressing ram and an ejecting ram and a hydraulic circuit for operating the rams, which circuit will provide a plurality of modes of operation, such, for example, as the agitation of the material being i pressed during the pressing operation; the subjection of the formed article to pressure between the rams. during the ejection thereof; the subjection of the formed article to pressure between the rams during a part only of the ejection stroke,

theejection of the formed article while being held between the rams without the exertion of pressure thereon, and the ejection of the formed article with the pressing ram separated therefrom.

An object of the invention also is to provide a v pressing mechanism having pressing and ejecting rams arranged in a hydraulic circuit of such type that the rams respond in unison to the operational characteristics of the control mechanism therea for, in other words, the control may be actuated to cause the pressing ram to be advanced into forming contact with the material; then, the control ma be manipulated rapidly between pressing and return positions to cause the ram to reciprocate through a portion of its travel and the ejecting ram will move in a similar manner, the placing of the control in return position causing the return stroke of the pressing ram which in turn causes the ejection stroke of the ejecting ram.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of embodiment of the invention is clearly shown.

In the drawings:

Fig. 1 is a diagrammatic view of a hydraulic circuit for a pressing mechanism constructed in accordance with the present invention. 7

Fig. 2 is a diagrammatic view of a slightly modified circuit.

Referring more particularly to Fig. 1 of the drawings, the numeral llldesignates generally a fluid pressure source which includes, a, reservoir H, a motor driven pump l2, a pressure relief valve l3 and fluid lines l4, l5 and I6 leading to and from the pump and from the valve [3 to the reservoir, respectively. Fluid line l5 has a branch I! extending therefrom to a control valve mechanism is employed to govern the flow of fluid under pressure from the source ID to -a primary pgwer unit designated generally by the numeral 2 The unit 20 includes a fluid cylinder 2| having a pair of sections 22 and 23 of different diameters. These cylinder sections 22 and 23 receive a piston unit with beads 24 and 25 disposed for movement in the sections 22 and 23, respectively, and connected by stem 25 to form a unit. Ram 21 projects from the piston 24 through the end wall of the cylinder to perform useful work. Fluid lines 28 and 32:. extend from the control valve mechanism i8, which. in the present illustration is of the conventional four-way type but for special operations may be of other types such as those illustrated in the copending applications of Cecil E. Adams, Serial Nos. 545,700 now Patent No. 2,464,283; 545,701, now Patent No.. 2,21 589,163; 594,963. to the cylindersections- 2.2 at-ope. posite ends of piston 24. Through the manipulation of the spool 31 of the valve [8,, fluid under pressure from the source may be alternately applied to opposite ends of piston 24 .to efiect reciprocation of the piston and the ram 21. The above mentioned copending applications illustrate the manner in which the control valve may be automatically or manually manipulated to -secure the reciprocation oi the. ram through either the. full stroke or part of such stroke.

To utilize the. pressing force ofthe ram 21, a

mold. 32 having av cavity 33 is supported in registration with the ram 21, the latter may be pro-. vided with a suitable tool for cooperation withthe mold .32 depending upon the shape of the article being pressed. In the present illustration, no additional tool is employed, the lower end of the ram entering the cavity 33. to form a slug 0r v I According to. the invention, the lower end of the. cavity 33 is closed by a second ram 35 which projects. outwardly from a piston as forming a part of a secondary power unit .31. This unit has a cylinder 38. and is arranged on the opposite side oi the moldslfrom the primary power unit,

the ram 35, in addition to forming the bottom wall of the cavity, serving .as. an ejector or knock out plunger for the finished article 34. The piston .32 and, ram 35 are normally urged toward a retracted position by a..spring All-surrounding the ram .35. between the piston 36 and the inner end of the cylinder 38-and when fully retracted, the outer end of the ram 35. will be properly positioned in the mold 32 for the formation of an article. This position may bevaried to change the capacity-of thecavity 33 through the adjustment of a stop means, such as the. screw 39, dise posed at the lower end of the unit for engagement by a balancing stem. projecting from the. piston .35 on the side opposite the ram 35.

In the operationoi the pressing mechanism, the mold cavity 33 is charged with the material to be pressed and the spool 3| moved upwardly, by .suitable means such as the foot lever 42 and shipperrod .23, todirect fluid from line l1 to line.

25 and the upper end of cylinder section 22. A portion of this fluid also flows from line. :28 through a branch line 44, past check valve 45 and through line 26. tothe enter and of cylinder section 23. The .force of this fluid acts upon the end of. piston head 25. and operates in conjunction with the .fluid supplied to the upper end of cylindersection 22 tomove the pistonand ram assembly in the power or working stroke. As the ram moves into the moldlcavity, the material therein is compressed to form the desired article. After the maximum pressure -for which the relief valve I3 has been set, has been exerted by the ram 21,- the lever 42 is manipulated to move spool 35 into position to direct fluid from line 11 through line 33 to the lower end of cylinder section 22 to efiect the elevation or retraction of ram 2?. In the formation of articles from some materials it may be desirable to impart a series of pressure impulses to the article being formed. This may be accomplished by oscillating the spool 3i between elevated and lowered positions after the initial pressing stroke of-the ram has been completed. When the pressing mechanism is provided with control means of the type shown in the above mentioned copending Adams applications, this series'of impulses, consisting of short reciprocations of the ram, may be either manually or automatically secured. As is customary in presses of this character, the fluid exhausted from cylinder 22 during the working stroke is returned tov the fluid reservoir through an exhaust line 41. On the return movement of the ram at least a portion of the exhaust fluid is utilized to effect the operation of the secondary power unit in the ejection stroke of the plunger 35. This feature is, accomplished by extending a branch line from the line 45 to the outer end of thesecondary cylinder 38. Thus when fluid is exhausted from cylinder section 23 it will flow through lines- 4t and is to the outer end-of cylinder-:38 causing piser 35. and piston 36 are retracted or returned totheir initial positions during each pressing stroke of the ram 21, the fluid beneath piston 36 being forced through lines 48 and 4.6 to the outer end of cylinder section 23. It will be obvious from the foregoing that when a series of impulses are imparted to an article, the ejection plunger ime parts a thrust to the article during each; upward movement of the pressing ram. In this manner, the material is agitated during the; forming op-. eration.

Since it is desirable in some instances, to have the pressing ram 21 move away from or separate from the formed article beiore the latter is ejected, only a portion of the fluid exhausted during the retraction of the ram in such in stances, is employed .to move theejection plunger. The efiective area of the piston used to operate this plunger is also calculated so that the fluid supplied to the cylinder 38 will cause the plunger 35 to move at a slower rate than the'ram 21. The check valve 25 between lines 46 and 44 prevents the fluid being exhausted from the outer end of cylinder section 23 from flowing to the exhaust line 31. It is essential, however, to permit this exhaust fluid to reach the exhaust line ll' after the piston 25 has completed its necessary stroke. A by-pass line 50 is, therefore, extended between lines it and 44 around the check valve 45. This by-pass line is provided with a pressure relief valve 55 which is adjusted to the maximum pressure necessary for the operation of the ejection.

plunger 35.

. When fully automatic operation is desired it is necessary to return the plunger 35 to a retracted position after the formed article 34 has been removed to permit a new charge of material to be inserted in the mold. This auto-. matic retraction of the ejector plunger is ssence formed withv a socket .52. forv the slidable reception of a valve plug 5.3. A spring 54-disposed be tween the plug 53' and the inner end of the sock et 52 normally urges the. plug to a. position to prevent communication between passages 55 and the socket 52, the passages extendingtothe inner'end of the head25.. The cylinder section 23 has an adjustable stop screw 56 projecting there-- into from the outer end; This screw is disposed to engage the plug 53 as the ram 2! and piston thereof are retracted and cause relative move-j ment between the plug 53 and the piston 25 whereby communication. between opposite ends ofthe piston head 25 will be established. When the passages and the socket 52 are in communication, the spring 4'8 may expand and force the piston 36 toward the outer end of the cylinder 38. Fluid beneath the piston 36. will be exhausted through-lines 48 and 46 to the outer end of cylinder 23;. Since communication is established between opposite ends of piston 25 this fluid will flow through lines 28, 44 and 51 to the inner end of cylinder 38. g

Pressure and suction created by the recipro. cation of the plug 53 are relieved by a small oriflce 58' extending through the plug and illustrated in Fig. 1 'bydotted lines.

In some instances it may be desirable to se:- lectively return the plunger 35 to a retracted position. For instance, it may be advantageous to retain the ejecting ram in an extended condition to support the formed article 34 until it may be manually removed. In such operation, the pressing ram and its piston structure may be fully retracted before the removal of the article. To prevent the automatic retraction of the ejecting plunger in the manner pointed out above, the stop screw 56 is adjusted until the plug 53 cannot-engage it during the retraction of the pressing ram. After the formed article 34 is removed, the plunger 35 may be retracted through'the operation of a normally closed valve 59 arranged in a by-pass line 6-0 extending between fiuid lines 48 and 51. If the valve 59 is opened'when the-plunger 35 is extended, fluid may flow through line 68 from one end of cylinder 38 to theother permitting spring so to move piston 36 and plunger 35 to normal, retracted positions. It' should be obvious that valve 59 could be-operated either manually or mechani-' v cally depending upon the nature of the work being performed.

The invention is susceptible to considerable modification. For example, Fig. 2 shows a by draulic circuit 65' of modified form for use on a pressing mechanism. As in the first form of the invention, the circuit 65 includes a fluid pressure source 86 similar to that shown at I 8 in Fig. 1. The pressure line 51 extending from the source 66 is connected to a control valve 68 which may also be of the conventional four-way or any other reversing type four-way valve. Cylinder lines: and H lead-from the valve 58 to the ends ofa power cylinder 12. Line 10 has a spring pressed" check'valve 13 incorporated therein for a purpose to be' later described. Cylinder; l2 slidably' receivesa iston 14 from one-end of which proa jects a ram this ram serves to do useful work and corresponds to ram 21 in the mechanism shown in Fig. 1".

- I The circuitof Fig. 2 also includes an ejection.

or knock-out plunger 16 corresponding to that indicated by in Fig. 1. Plunger; 16 forms. a part of a piston 11 disposed for reciprocation; in. cylinder 18.- A coil spring surrounding plunger.

1.6 and engaging piston 71 resiliently urges the plunger toward a retracted: position. This later position is determined by a stop screw 80 ad.- justably. receivedby the outer end of the cylinder 18.

V In Fig. 2, the circuitincludes a pressure operated valve sl having a spool 82 disposed for sliding. movement in a cylinder 83. Fluid lines 84and8'5 extend to opposite ends of this cylinder, line-84 branching from line 10 and line- 85 leading from the outer end of the cylinder 12. When. fluid. is. directed from. the pressure source .66. to the outer end of the cylinder 12 bythe valve 68, the springpressed check valve will resist now through the line 18 causing a slight increase in pressure in line 10 which will be transmitted by line to the end of cylinder 83 and applied tothe endof spool 82 to move the same to a position to pre'ventoommunication between line 85' and'a line .86 leading from valve 8| to the lower or outer endofcylinder'lB.

After'ram '15 has completed a pressing stroke, valve 68 is operated to direct fluid from the pressure source to thelower or inner end of cylinder. l2'to effect the retraction ofthe ram.75. When ram 15 so moves, fluid exhaustedfrom the outer end of cylinder l2 will-be'prevented from flowing to va1ve'68 through line Why the check valve 13. Such exhaust fluid must, therefore, flow through line 85 to cylinder as where its force will be applied to' the end of spool 82 to move it to a valve opening position.v The fluid may then flow through-line 86 to the outer end of cylinder 18. Line 86 contains a pressure relief val-ve 8'! and a normally open spool valve 88 which is arranged to be operated by a cam 98,

v fixed for movement, in this instance, with ram 15. It should be obvious that cam 98 could be moved either by-handor by some other mechanismif desired.

When ram 75 is being retracted and a valve 88 is open-allthe'fluid being exhausted from cylinder 12 may fiow'tocylinder 18. This fluid will tend to cause theram 16 to move at a greater rate than ram 75. In'the formation ofsomeproducts this tendency is desirable because it is advantageous to exert a squeezing action on the product'as it is being ejected. The force exerted by the ram 16 is determinedby thesetting' of the relief valve 81' which also serves to relieve. excessive pressure if f ram 16 should be stopped'before reaching the end of its travel orwhen this'ram reaches the limit of its I movement retracted.

Some products require the relative positions of the rams T5 and 16 to be maintained throughout a now control mechanism 9d of conventional'com struction arranged in a by-pass line fizextending. around valve 88: To renderthe mechanism 91.

eifeotive; valve 88" must be closed by cam. 58 or.

otherwise at some Point during the retraction oi;

ram 15 If the ram 15 be required to separate.

from the article during ejection, the mechanism' 9| is adjusted to cause plungerv it to. move at a slower rate than ram [5, the. excess of exhaust fluid necessary. to operate'plun'ger 15 being. re.- turned tozthe reservoir. by relief valve 87..

Retraction ofjplunger 'lGjis effected by opening a. normally closed-valve 93 connected in a fluid line 9'4jdisposed betweenline .86 and another liner95 15 connecting the upner. -or inner endof cylinder '1.8.-

before ram is completely 'aaaooc of the invention first described, valve 68 may bemanually operated, or-valve means of the type shown in the above mentioned copending applications may be provided which will automatically operate, to impart a series of sharp pressing impacts to the article being formed. During this series of impacts, the pressing ram is repeatedly advanced and retracted and similar movement of the ejecting plunger also occurs, the latter being retracted as the former advances. To permit this retraction of the ejecting plunger or ram it is necessary to provide an outlet for the fluid in the outer end of cylinder 18. Such an outlet is secured in the circuit shown in Fig. 2, by extending a fluid line 9'! from the cylinder 83, between the lands on the spool 82, to the reservoir of the pressure source 66. Thus when fluid pressure is from said first power unit during retraction of said first ram to said second power unit to cause the projection of the second ram; means for limiting the projecting movement of said second ram; relief valve means in said fluid conducting means to limit the pressure in said fluid conducting means after the motion of said secondjram has been limited; means normally urging said second ram toward a retracted position; and valve means operatedby the piston of the first power unit at a predetermined point during the retraction of the first ram to discontinue the direction of exhaust fluid to said second power unit and direct it to exhaust, said valve means also serving at the same time to establish communication between the opposite ends ofsaid second power unit.

3. In a hydraulic pressing apparatus, a source of fluid pressure; first and second power units having reciprocable rams; a control valve mechanism between said source of pressure and the supplied to line 18 to cause the advance of ram l spool 82 will be moved to a position to interrupt communication between lines 85 and 86 and establish a connection between the latter and line 91 whereby fluid exhausted from the outer end of cylinder 18 may flow without obstruction to the reservoir. 7

The circuits shown and described, as well as others falling within the scope of the appended claims are particularly suited for use in pelleting or similar operations wherein material is supplied to a mold, a pellet is pressed, the pressing die is retracted, the pellet is ejected, the ejector retracted, and a fresh charge of material supplied to the mold. By utilizing fluid exhausted upon first of said power units, said valve mechanism being operative to effect the reciprocation of the first ram; fluid conducting means connecting the outer ends of said power units to apply fluid exhausted from the first power unit during retraction of the first ram to said second unit to cause the retraction of the pressing ram, for operating the article ejector these operations are properly synchronized without the necessity of extraneous timing mechanism,

While only two circuits have been illustrated, it should be obvious that many minor modifications may be made therein without departing from the fundamental principles set forth in the following claims.

7 W e claim:

1. A mechanism for pressing articles comprising a source of fluid pressure; a power unit having a ram for cooperation with forming tools and piston sections of different areas connected with said ram; means for directing fluid from said pressure source to said power unit to move said ram toward and away from said forming tools; means for ejecting a formed article from the forming tools, said means having a second power unit with a ram and piston; and means connecting the first and second power units and operating to apply fluid exhausted by the piston section of the first power unit having the smaller area to the piston of the second power unit to effect movement of the second ram and ejection of formed articles; and, means forming a part of the smaller piston section of the first power unit for interrupting the application of exhaust fluid to the piston of the second power unit when said first power unit reaches a predetermined stage of operation.

2. In a hydraulic pressing apparatus, a source.

of fluid pressure; first and second power units having reciprocable rams; a control valve mechanism between said source of pressure and the first of said power units, said valve mechanism being operative to effect the reciprocation of the first ram; fluid conducting means connecting the outer ends of said power units to direct fluid exhausted the projection of the second ram; means normally urging the second ram toward a retracted position; a valved passage means operative when said first ram reaches a predetermined point during retraction to establish communication between the opposite ends of the cylinder of said second power unit.

4. In a hydraulic pressing apparatus a source of fluid pressure; a power unit having piston and cylinder sections of diiierent areas; control valve mechanism between said pressure source and said power unit; said control mechanism being operative to effect the reciprocation of the piston section of said power unit, a second power unit disposed in opposed relation to the first-' mentioned power unit; fluid conducting means establishing communication between the outer ends of both sections of said first and said second power units; means normally tending to move the piston of said second power unit to a retracted position; and valved passage means operative when the piston section of said first power unit reaches a predetermined position during retractive movement to establish communi-' cation between opposite ends of the smaller cylinder section of said first power unit.

5. In a hydraulic pressing apparatus, a source of fluid pressure; first and second power units having reciprocable rams; a control valve mechanism between said source of pressure and the first of said power units, said valve mechanism being operative to eiiect the reciprocation of the first ram; fluid conducting means connecting the outer ends of said power units to apply fluid exhausted from the first power unit during retraction of the first ram to said second unit to cause the projection of the second ram; means normally urging the second ram toward a retracted position; and valved passage means operative when said first ram reaches a predetermined point during retraction to establish com-- of fluid pressure; first and second power. units having reciprooable rams; a control valve mechanism between said source of pressure and the first of said power units, said valve mechanism being operative to effect the reciprocation of the first ram; fluid conducting means connecting the outer ends of said power units to apply fluid exhausted from the first power unit during retraction of the first ram to said second unit to cause the projection of the second ram; means normally urging the second ram toward a retracted position; and valved passage means operative when said first ram reaches a predetermined point during retraction to establish communication between the opposite ends of the cylinder of said second power unit and a second means selectively operable to establish communication between the opposite ends of the cylinder of said second power unit prior to the time the first ram reaches said predetermined point in its retraction movement.

7. In a hydraulic pressing apparatus, a source of fluid pressure; a power unit having piston and cylinder sections of different areas; control valve means between said pressure source and said power unit; said valve means being operative to alternately connect the inner and outer ends of the larger cylinder section of said power unit with said pressure source to effect reciprocation of said piston sections; a second power unit having a piston and cylinder disposed in opposed relation to said first power unit; a fluid passage establishing communication between the outer ends of the smaller cylinder section of the first and the cylinder of said second power units; a second fluid passage establishing communication between the outer end of the larger cylinder section of the first power unit and the inner end of the second power unit; a check-valve containing passage connecting said first and second passages, said check valve limiting fluid flow to a direction from the second to the first passage; another valved passage operative when the piston sections of said first power unit reach a predetermined position during retraction to establish communication between the outer ends of the cylinder sections of said first power unit; and means yieldably urging the piston of said second power unit toward a retracted position.

8. In a hydraulic pressing mechanism, a source of fluid pressure; a power unit of the piston and cylinder type; a control valve mechanism between the pressure source and said power unit, said valve mechanism being operative to alternately connect the ends of said cylinder to said pressure source to effect reciprocation of said piston; a second power unit of the piston and cylinder type mounted in opposed relation to the first power unit; a fluid conductor connecting the outer ends of the cylinders of said power units; and valve means in said conductor responsive to fluid pressure when the outer end of the cylinder of said first power unit is connected with said pressure source to interrupt communication between the outer ends of the first and second cylinders and to connect the latter to exhaust.

9. In a hydraulic pressing mechanism, a source of fluid pressure; a power unit of the piston and cylinder type; a control valve mechanism between the pressure source and said power unit, said valve mechanism being operative to alternately connect the ends of said cylinder to said pressure source to effect reciprocation of said piston; a second power unit of the piston and cylinder type mounted in opposed relation to the first power unit; a fluid conductor connecting the outer ends of the cylinders of said power units; a flow control mechanism for regulating the rate of movement of the piston in said second power unit; and valve means in said fluid conductor operative to render the flow control mechanism effective.

10. In a hydraulic pressing mechanism, a source of fluid pressure; a power unit of the piston and cylinder type; a control valve mechanism between the pressure source and said power unit, said valve mechanism being operative to alternately connect the ends of said cylinder to said pressure source to effect reciprocation of said piston; a second power unit of the piston and cylinder type mounted in opposed relation to the first power unit; a fluid conductor connecting the outer ends of the cylinders of said power units; and valve means in said conductor responsive to fluid pressure when the outer end of the cylinder of said first power unit is connected with said pressure source to interrupt communication between the outer ends of the first and second cylinders and to connect the latter to exhaust; a flow control mechanism for regulating the rate of movement of the piston in said second power unit; and means operated by the piston of said first power unit at a predetermined point in the retraction thereof to render said flow control mechanism eifective.

CECIL E. ADAMS. ELLIS H. BORN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,112,466 Maloon Mar. 29, 1938 2,192,778 Stacy Mar. 5, 1940 2,243,716 Monroe May 27, 1941 2,280,849 Pocock Apr. 28, 1942 2,337,578 Schultz Dec. 28, 1943