US2296072A - Hydraulic press - Google Patents

Description

Sept. 15, 1942. I

HYDRAULIC PRESS Filed Nov. 20, 1939 7 Sheets-Sheet l IITE.1

Imam-on WARREN R. TUCKER BY WvW Anoaueva Sept. 15, 1942. w. R. TUCKER HYDRAULIC PRESS Filed Nov. 20, 1939 7 Sheets-Sheet 2 mm T K M E T .m R 4r N E R m w. m 8 u a 4 n3 f Sept. 15, 1942. w, R ER 2,296,072

HYDRAULIC QPRESS Filed Nbv. 20, 1939 7 Sheets-Sheet 3 I NVENTOFi WARREN RTUCKER ATTo RNEYS Sept; 15,- 1942 W. R. TUCKER HYDRAULIC PRESS 7 Sheets-Sheet 4 Filed Nov. 20, 1959 WARREN R. TUCKER Mm's Ann RNEYS S p 9 w. R. TUCKER 2,296,072

HYDRAULIC PRESS Filed Nov. 20, 1939 Sheets-Sheet 5 Y RY n g:

V l- 3 e Z :5 7" z L I q- 2 5% J w INVENTOR WARREN R.TUCKER BY W rm;

A'r'reRuaYa HYDRAULIC PRESS Sept. 15, 1942.

Filed Nov. 20, 1939 7 Sheets-Sheet 7 .IITSJU 1' be 93 a WARREN R. 5 1m YWTM Inn RNEY the press.

Patented Sept. 15, 1942 UNITED STATES PATENT OFFICE P -zsasuso'zz l masonic mass Warren a. Tucker, Dayton, Ohio, assignonto The Hydraulic Development Corp. Inc., Wilmington, Del., a corporation of Delaware Application November 20,1939, Serial No. 305,356

' (c1.1s-1c) 10 Claims;

\ This invention relates to a hydraulic press and more particularly to a hydraulicpress in which the main ram is eliminated and the head of the press is moved as a unit towards the bed of the i press by means of pistons located in the lower part of the press and operatively connected to the head of the press by rods which are employed in place of the stationary tie rods conventionally heretofore employed. a

Itis an object of the present invention to provide a hydraulic press of simplified construction Fig. '7 is a fragmentary vertical section showing the die halves in closed position and showing the associated mechanism including the knockout or ejecting mechanism.

Fig. 8 is a horizontal section in the direction of the arrows.

whereby the press is less expensive to build and maintain without sacrificing the advantages of the conventional hydraulic presses heretofore l-available.

Another object is to accomplish the foregoing object while providing for veryrapid movement of the head of the press which carries the upper Fi 9 is a vertical section on the line 9-9 of Fi 3.

Fig. 10 is a perspective exploded view of the knockout mechanism on one side of the press; the knockout mechanism on the other side oi! the press is identical.

knockout mechanism onqthe employed in carrying. out what is known as compression molding; in this connection the typical press to be described includes special mechanism for ejecting the molded piece after molding hm been, completed, this ejecting mechanism bein particularly adapted to use with the compression molding press described herein.

I Another object is to provide double-acting means which .is separate from the main. press operating means, for carrying out the operations of fast traverse and of pushing. back of the press head. i

Still otherobjects will more fully hereinafter v appear.-

Referring to, the' vaccompanying drawings;

Fig. 1 is a iront' elevation of a compression molding press embodying the principles of the present invention, with the head at,-the position where it is most widely separated from the base,

and the knockout mechanism actuated. f

Fig. 215 a side elevation of the press. Fig. 3 is a vertical section taken on the line 3-'3 of Fig. 6, .through-one of the main cylinders in the, lower'part of the press.

Fig. dis a rear elevation of the lower part of Fig. 5 is a'diagrammatic view of the complete press, showing the hydraulic circuit.

Fig. 6 is a horizontal section taken on the line .4 of, Fig. 4 through the bottom of the press.

" Fig. 11 is a detailed sectional view showing the operation of the lower knockout mechanism during an ejecting operation-by which the molded piece is ejected from the mold when the (lie halves'are about to attain their most separated position.

Fig. .12 is a similar view'sl wing the lower knockout plate after resettingthereot by the operator. T

Fig. 13 is a similar view but showing the lower head of the press.

General arrangement In the press which is illustrated in the drawings and which constitutes a typical embodiment of the present invention, the conventional stationary press head and tie rods are replaced by a vertical movable head to which is, fixedly secured the upper die half or. equivalent forming or pressing member, and by rods which are tlxedly attached to the press head and. to hydraulic pistons operating in cylinders formed by orassociated with the .bed of the. press upon which the lower die half or-the like is mounted. Thus, the rodsconstitute in eilect very elongated plungers,

and the upper diehalf is broughtinto pressing engagementwith the lower die half by exerting hydraulic'pressure downwardly on the plunger.

rods which are fixedly; attached to the head.

The major part of thedownstroke is carried out v by means or auxiliaryhydraulic pistons which 7 are effective to move, the press head at veryhi gh speed until the pressing operation is aboutto. begin, whereupon automatic adjustable mechanism causesthe fluid pressufe tobe applied additionally to the main pistons. Thus, theauxiliary pistons exert alboosting action on the downst'roker, l

The return oi the. press head} upwardly is acconi plishedby 'exertin'g hydraulic. pressure ran; the, opposite sides of the auxiliarypistons, this" known as the push-back" operation. Suitable I through the top of the press on the line 8-8 of Fig. 9, looking downstroke o t'the matically and at the proper times the application of fluid pressure to the appropriate portions of the press. The booster and push-back pistons are operatively connected to the press head by means of plunger rods which are similar'to the main plunger rods and similarly extend from the pistons which are located in the base of the press into fixed attachment with the press head.

When carrying out compression molding, the press is desirably provided with knockout means for ejecting the molded article from the die half in which it is retained after the upward return of the press head is begun and preferably towards the end of the return stroke.

Referring more particularly to the accompanying drawings, I designates the vertically movablehead of the press and 2 designates the stationary bed of the press. The head I of the press is in the form of a suitable casting which is hollow so as to act as a portion of the hydraulic liquid reservoir, the remainder of the Y hydraulic liquid being carried in the bed 2 of the press which is similarly hollowed out to form an oil reservoir. The upper mold half 3 is carried on the head I of the press by means of of nuts 8 (see Figs. 8 and 9) and vertically dependent therefrom are four main plunger rods 9, and these plunger rods 9 integrally or fixedly carry at their lower ends main pressing pistons I9 which are reciprocably received in main pressing cylinders II which are fixedly carried by the bed 2 of the press (see Fig. 3). The main plungers 9 are sealed at the point where they enter the cylinders II, as at I2 (Fig. 3). These main plungers 9 are operated directly only during the main pressing operation, as will presently appear.

The hydraulic liquid employed is carried in a reservoir which is made up of two parts, one of which is formed in the stationary bed 2 of the press and the other of which is formed-in the movable head I of the press. The lower portion of the reservoir is formed inwardly of the main pressing cylinders II and is designated I3, thiscavity I3 being suitably formed in the castin which'constitutes the bed 2 of the press. The

7 head of the press is formed with six oil cavities I4 (see Figs. 8 and 9), these cavities I4 being interconnected by -;-passageways I5 suit ably disposed'through the partitions I 9 in the head of the press; The-main plunger rods 9 extend into these cavities I4 and are formed axially with bores "which extend to the botmeans of passageways I3 (Fig. 3) in the walls Booster and pushbaclc plungers Fixedly attached to the head I and extending downwardly therefrom are a pair of auxiliary plungers I9, theseplungers l9 being fixedly secured within the end compartments ll of head I by means of nuts 20 (Figs. 8 and 9). Plungers' common conduit 39.

control means are provided for effecting auto- I9 extend downwardly into the press bed 2 and carry on their lower ends pistons 2I which operate vertically within cylinders 22 which are formed in any suitable manner in the press bed. The plungers I9 are nearly as large in diameter as the pistons 2I mounted thereon and consequently when hydraulic pressure is applied above pistons 2I the plungers I9 are drawn downwardly at a very rapid rate, the effective area being very small. However, on the return stroke when oil under pressure is applied beneath pistons 2I, the full area of pistons 2I is effective and return is not as rapid. This fast downstroke is of advantage because it enables the head I of the press to be brought rapidly into the position where pressing is ready to begin, thus saving time. The action of forcing plungers I9 downwardly causes main plungers 9 to be moved downwardly, and as plungers 9 so move, pistons I9 cause oil to be sucked into the spac above pistons I9 through conduits 23 (Figure 6) which lead directly fromthe upper portion of cylinders II into the oil cavity I3. The conduits 23 are provided on their inward ends with check valves 24 which allow oil to be sucked outwardly but prevent its return. Thus pistons I 0 are prevented from drawing a vacuum as they are pulled downwardly by the auxiliary pistons 2|.

I As the head of the press approaches the position where actual pressing is about to begin, the application of hydraulic pressure is automatically shifted so that hydraulic pressure is applied downwardly both upon pistons 2I and upon main pressing pistons III. This shift is effected as follows: An ear 25 fixedly carried in any suit- 21 downwardly against the action of spring 29 which is disposed between an car 29 mounted on bed 2 and an adjustable collar 39. This causes the lower camv end @of nod 21 to move inwardly a rod 3I and to thereby shift a piston 32 (Fig. 5) of a two-way valve 33 so as to admit liquid under pressure to the spaces above main pistons I9 through conduits 34. As indicated in Fig. 6, the spaces above main pistons II) at each end of the press are placed in communication with one another by passageways 35 which are suitably cored in the casting constituting the press base 2.

Liquid under pressure is admitted to the spaces above auxiliary pistons 2I during the fast travto conduits 38', these conduits 38 merging into For returning the head I after a pressing eration, the pistons 2I are employed, by ic pressure being applied below them by suitable operation of the .controls. This causes plungers I9 t move upwardly, carrying head I and with it pl gers 9 and pistons II. The drawing of a suction by pistons Ilon their upward stroke is prevented by their free connection withthe .oil cavity I3 by means of passageways II. One of the secondary features of the press of this in-.

vention is the simplicity of piping, the connection between reservoir I3 and cylinders II being merely by way of ports in the cylinder walls.. Likewise, the spaces above the pistons II are connected to the cavity II by similarshort conduits 23 in the cylinder walls leading to the check valves 24 which are located in the cavity II, this check valve'being continually exposed to the oil in the reservoir by reason of the fact that cavity I3 is always full, being supplied with oil at all 3 times from cavities i4 through bores II' in 'plungers 9. v

The feature of having tw oil reservoirs which are in continuous communication with one anthe spaces above pistons 2!, for causing the rapid traverse, and subsequently for; aiding in the pressingoperation after two-way valve 33 is opened,

other and one of which is in the base and the I other in the pressing head,'serves the purpose of utilizing the'spaces which occur in these parts and of providing a head of pressure for filling the main cylinders ll during the upward movement and the first part of the downward movement of the pressing head I.

Hydraulic circuit While the hydraulic circuit has been referred to to some extent above, it is desirable to describe it in detail with reference particularly to Fig. 5. Oil under pressure is constantly supplied by a one way variable Idelivery pump 40 driven by motor 4| and withdrawing oil through conduit 42 from tank l3 and passing it under pressure through conduit 43 to a four-way valve 44.\ Leading from four-way valve 44 is a conduit 45 which leads to the normally spring-closed two'way valve 33 which is in communication with the inlet conduits 34, leading to the spaces above main pistons l0, by a conduit 45. 'Thusfluid pressure transmitted to conduit 45' is prevented from being admitted to the spaces above pistons ill except when ear has actuated springurged rod-3i so as to open thetwo-way valve 33, this takingplace only when the pressing operation is about to begin andwhen it is desired'to have a very great force applied to the pressing elements, namely mold halves 3 and 5.

Conduit as is connectedto'four-way valve 44 and is adapted to lead pressure fluid tothe spaces below auxiliary pistons 2| when it is desired'to return thepressing head to its upward position. Four-way 'valve 44 contains a shifting member 41 which is adapted to connect the pressure liquid from conduit 43 to either conduit 45 or to conduit 39. The four-way valve 44 is also provided with a common return conduit 43 which connects both ends'of'valve back-to the tank l3 and which is thus adapted to convey fluid returned either -byconduit back to-the tank 13.

Conduit 43 is connected backto the tank by 45 or by conduit 33 a conduit 49 in which is disposed a safety valve 55 which is adapted to'open only under emergency to. allow the outputof pump 40 to be returned to tire tank.

solenoid 54 is provided. When this solenoid 54 is energized by, any suitable means under the control of the operator, valve member 41 is shifted upwardly f Fig. 5, causingthe application of pressure liqu' d to the spaces above auxiliary pistions 2| and the simultaneous return of liquid from below pistons 2i by way of conduits 39 and 43 to the reservoir i3.

In 'order to limit the upward movement of pushback or auxiliary pistons 2| and thereby to limit the upward return of press head I, in order to hold press head i in this upwardposition, and in order to by-pass the output of pump 40 while so holding the head i, the following means is provided. A conduit 55 is disposed in the wall of one of the cylinders 22 at a point'just below the desired upward position of piston 2| in that cylinder and this conduit 55 is connected to conduits 35 and 31. A check valve 55 is disposed in this conduit 55 in such .manner that it allows liquid to pass outwardly from thespace in cylinder 22 to the conduit .31 and'thence byway of I conduit 43 back to the reservoir l3, but, prevents the flow of pressure liquid from "conduit 31 through conduit 55 into cylinder 22. Thus, during the pushback operation, when piston'2l is below the point of connection of conduit 55, the liquid above piston 2| is. adapted to flow out wardly either through-conduit 55 or through conduit 35.. However, when piston 2 i moves upwardly-of the connection of\ conduit 55 to cyl-. inder 22, thepressure liquid admitted from conduit 33 to the interior of cylinders. 22, is freely passed outwardly through check valve 55 into conduit 31 and thence back to the tank l3. Should pistons 2| and had l dlOp slightly so,

as to cover up the port of conduit 55,*the pressure liquid would immediately force-them up- 'wardly until the port of conduit 55 wasuncovered. In this way, the pistons 2i and with them the head I and main pistons it are held intheir uppermost position, this uppermost position is predetermined, and as they arev so held, the

. output of pump 40 is by-passed. As will be ob- The valve member 41 is normally held in the I valve 33.

A spring 53 normally holds valve. member 41 in the position shown in Fig, 5. In order to shift valve member 41 atthe desired time so as vious, it is generally desired to 'placethe port of conduit 55 on the'booster side of the cylinder 22, adjacent the port of conduit 35, whereby the pistons 2| are-located and held near the top of cylinders 22. However, if desired, the port of conduit 55 may be located at any point on the cylinder wall 22'. I

\ Operation of press i While the operation of the press proper .will" be in large part obvious from the foregoing description, it maybe reiterated as follows. Motor H ,is first started, causing pump 40 to deliver liquid. Four-wayvalve 44 is in'the position of Fig. '5 while the press is at rest and-consequently the pressure output from conduit 43 will be de-,- livered through conduit 38 to the spaces below auxiliary pistons 2|, causing them to rise in eylinders 22, thereby elevating the head I of the press to its uppermost position if it is not already at said position. As the pistons 2| 'ri'se, the pressure liquid' above them will be forced outwardly through conduits 36 and 31 and thence through the upper portion of four-way valve 44 to the return conduit 48 which leads back to to admit pressure liquid to conduit and thence through conduit 3 which connects conduit 45 tothe reservoir l3. As the head I approaches its uppermost position, the port of conduit will be uncovered and-the liquid will' be by-passed that ear 25 will engage collar 25 in such manner through check valve 55 to the tank IS in the manner just described above.

As the auxiliary pistons 2| are elevated, the main pistons III will be correspondingly elevated in their cylinders H by reason of their connec- 5 .tionto head I by plungers 5, causing the liquid above pistons It to return to the tank It by way of conduits 34. conduit 5| and check valve 52, conduit 45, the upper portion of four-way valve 44, and return conduit 45 to the reservoir l5. ro

Assume now that it is desired to eifect downward travel of the headin a pressing opera tion. Solenoid 54 will be first energized by any suitable means under the control of the operator, causing valve member 41 in four-way valve 44 to shift upwardly of Fig. 5, thereby causing the pressure liquid from conduit 45 to be connected to conduit 45. The liquid from conduit 45 cannot flow at this time into the spaces above main pistons l5 because two-way valve 53 is still closed and check valve 52 prevents movement of the liquid from conduit 45 into conduits 54. Ac-

cordingly, the liquid is directed from conduit 45 into conduit 51 and thence into the spaces above pistons 2|, it being prevented from going into the spaces below pistons 2| by the action of check valve 55 untll'the piston 2| has traversed the port of conduit 55. Pistons 2| now'exert a traversing action upon the head I, bringing it downwardly. As head I isthus traversed at high speed downwardly, the liquid beneath pistons 2| is caused to be returned to the tank It by way of conduits and 44 which are now in connection by reason of the positioning of valve member 41. Simultaneously, the liquid below 35 main pistons I5 is forced downwardly and into tank It by way 'of passageways l5, and liquid from tank It is sucked upwardly through check valve 24 and conduit 25 into the spaces above pistons l5.

Assume now that the traversing operation has been completed or substantially so and that the actual pressing is about to begin. The adjustable collar 25 on rod 21 will have been so adjusted as to cause opening of two-way valve 33 at .this Point. The pressure liquid in conduit. will now be directed through valve 53 into conduit 45 and thence into the spaces above main pistons III which are already filled with liquid under atmospheric pressure from tank It. The pressing operation is now commenced and is carried out by the exertion of pressure downwardly on main pistons It and simultaneously the downward exertion oi, pressure upon auxiliary pistons 2|, which now exert a booster action. This pressing condition continues until the pressing operation is completed whereupon solenoid 54 is deenergized either manually or automatically so as to cause valve member 41 to move downwardiv 01 Fig. 5, causing liquid under pressure to be again transmitted through conduit 35 to the spaces below auxiliary pistons 2| which new again exert their'push-back function. As the pistons 2| move upwardly, they carry head I and pistons l5 upwardly, the liquid above pistons l5 discharging through conduit 5| and check valve 52 to conduit 45 and thence through conduit 45 back to the tank.

a When carrying out compression molding, it is desirable to hold the mold halves closed under pressure at the end of the pressing operation. Moreover, the speed of downward travel of the. head l-will decrease considerably during the pressing. In order to take care of the decreased 75 aaaao'm amount of pressure liquid thus allowed to be admitted to the spaces above pistons I5 and 2| .and in order to prevent damage to the pump 45,

means is provided for shifting the pump 45 to compensate for these effects. This means is well known in the art and is not described specifically but takes the form of a conduit 5'I (Figs. 2 and 4) which communicates the pressure in conduit 43 to a cylinder 55 on one side of the pump 40 and causes movement of a piston in the cylinder 55 against the action of a spring (not shown) mounted in a chamber 55 on the opposite side of the pump .45 and adjusted by hand wheel 55 to effect shifting of the shift ring in pump 45 so as to reduce the delivery of the pump 45 to the required extent. 'If it is desired merely to hold the head down under pressure, the output of pump 45 is reduced to a point where only suillcient liquid is delivered to compensate for leakages which may occur past pistons l5 and 2|. In this way. the head I is'forced downwardly until a maximum pressure is"exerted, whereupon this pressure is maintained for the desired time,

Eiecting mechanism The mechanism for ejecting the molded article from the mold is shown more particularly in Figs. 7 and 10 to 13. The knock-out or ejecting mechanism is employed to remove the molded article from the mold half to which it adheres as the mold halves approach their point of most complete separation. The ejectingmechanism shown in the drawings comprises a pair of upper knockout plates 5|, one at each side of the press, and a pair of lower knockout plates 52 disposed one,directly below each upper plate 5|. Plates 5| and 52 are provided with bores 53 which slidably receive the plungers 5 and I5. The upper bolster 4 is formed with an elongated recess 54 into which is received a flat plate 55 which is fixedly attached at its ends to the knockout plates 5| and which is substantially thinner than the depth of recess 54. The lower bolster 5 is similarly provided with a recess 55 in which is pins 55 which are adapted to engage the upper face of a plate 55 which is vertically slidably carried in a recess I5 and which carries a plurality of knockout pins H and a pair of positioning pins "which are adapted to engage the upper surface of the lower mold half 5 and thus to push plate 55 upwardly so that pins II are flush with the interior of the mold half 5.

The lower plate 51 carries a pluralityof upwardly extending pins I3 which are adapted to engage a plate 14 vertically reciprocably mounted in a recess 15 in the lower mold half 5. Plate 14 flxedlycarries a plurality of knockout pins 15 which are slidably received in the lower half and which are flush with the inner surface of mold half 5 when plate 14 is resting upon bolster 5. a x a As a result of the construction so far described, it will be apparent that when knockout plates 5| are moved relatively to bolster 4, knockout pins .will be actuated, projecting into the mold cavity when plate 55 approaches the bottom side of recess 54. correspondingly, when knockout plates 52 move relatively to bolster 5, the knockout pins 15 will correspondingly move relative to the mold half 5, being'iully projected thereinto when plate 87 is in contact with surface of recess 88.

the upper" Threaded in the upper knockout plates 8| are a pair of vertical rods 11, the head I being cored out at 18 to receive the projecting ends of these rods. Rods 11 are provided with a depression I8 to receive a spanner wrench for adjusting. them with respect to plates 8|. These rods extend slidably through the lower knockout plates 88, and thhce through recesses 88 in a latch plate 8| into bores 82 in base 2. Latch plate 8| is slidably carried on the under surface of lower knockout plate 82, being retained by a guide plate 9| fixedly carried by knockout plate 82 and by side guide 82 and rear guide 88. As latch plate'8| is lifted, it lifts knockout plate 82 with it, and knockout plate 82 is carried downwardly by its own weight. The rods TI are provided with an annular groove 83 located at an appropriate point thereon, and with a collar 84 which is adjustably disposed between groove 88 and the upper knockout plate 8|. Latch plate 8| is slidable fore and aft withrespect to'the press by means of apair of arms'85 pivoted on the lower knockout plate 82 and adapted to be operated simultaneously by ahandle 88 so as to abut against an abutment 81 to thereby move the latch plate8| rearwardly against the action of spring 88 which bears against rear guide 83 and which normally urges the latch plate 8| forwardlyQ As a result of the foregoing construction, as pressing head I is moved toward the base 2 of the press, the collars 84 will engage the lower knockout plates 82 just as the mold-halves 8 and! are about to come together andwill cause the upper knockout plate 8| to remain stationary and plate 85 to traverse the recess 84 into the position of Fig. '7, thereby fully retracting the pins '88. .The

88 to be fullyretracted upwardly of its slot 18 and cause knockout pins II to be withdrawn to the flush position. Meanwhile, gravity will hold the lower plates 82, 81 and I4 in the downward position, thereby causing knockout pins 18 tobe retracted to a point flush with the mold cavity.

As head I moves downwardly-untilcollars 84 rest upon knockout plate 82, the lower portion of rod'" is received downwardly in the bores 82 in the base 2, the. notch 83 sliding .past the inclined surface 89 of locking projection 80 which is integral with latch plate 8|, causing latch plate 8| to move leftwardly of Fig. 13,(rearwardly) to a position past that shown in Fig. 13. This prepares the assembly for the opening of the mold. It will be understood that the knockout pins. II and 18 have been retracted in order toallow filling of the mold without marking of the article-to be molded. 1 A t Subsequently, after molding has been completed, the controls will be manipulated .to causehead to be .returnedupwardly. I As this occurs, rod 11 will be carried upwardly and as recess 88 passes latch 88, latch 80 will be spring-pressed forward- -ly into latched relationship with rod 11, causing knockout plate 82'to be lifted by the upward movement of rodjl'l'. This is indicated in Fig. 11. This. action takes place near the end of the re 88 inwardly, causing unlatching of the latch plate 8| from rods 11 and causing the'knockout plate 62 and the associated parts to lower into the position of'rigure l2 where they rest upon the base f the press and where they are ready for a, subsequent pressing operation. 8

The foregoing descriptionrelates especially to the case where the'molded article adheres to the lower mold half. If the molding conditions are such that the article adheres to the upper mold half, the upper knockout pins II eject it as follows. As the press opens, the lower knockout plate 82 is carried upwardly by the latched engagement of latch plate 8| with rod 11. This continues as described above until the plate 81 strikes the top of its recess 88. When this happens, the whole knockout mechanism, both top and bottom, is arrested while the press head-l and. the mold half 3 continue in their movement. This causes the'upper plate 85 to traverse its slot 84 in the bolster 4 and to therebyrcompel relative movement of knockout pins 1| through the upper mold half 3, causing ejection of the article.

resting of pins 12 upon the upper surface of mold a half 5 will cause the knockout pin carrying plate cause the press head to come downwardly.

As will be apparent from the foregoing, when the lower knockout plate .62 is reset by means of handle88, the upper plate 85 is in its lowermost position against the bottom of recess 84, so that knockout pins 1| are projected into the mold cavity while the lowerknockout pins 18 are flush with. their cavity by reason of the action of gravity upon knockout plate 82 and the plates 81 and I4 associated therewith. As the press head I moves downwardly, the collars 84 serve to reset the upper plate 85 and the engagement of pins 12 with the upper surface of mold 8 causes the resetting upwardly .of the knockoutpins II. V

It will be seen from the foregoing that the knockout mechanism provides for the projection of knockout pins into either mold half upon a single movement of the mold halves, namely upon their separating movement towards the. end 7 thereof.

In operation, theoperator will first reset the lower knockout plate 82 by pushing handle 88 inwardly and will then energize solenoid 54 to After the molding operation, the operator will deenergize solenoid 54 whereupon the press -,will open and election will automatically occur towards the end of the opening stroke regardless of to which mold half the molded article ad heres. The operator will then reset the plate 82,

i and the cycle willbeagain repeated.

. I wish it to be understood that I intend to .includeas within my invention such modifications as may be necessary to adapt it.- o varying conditions and uses and as fall w in the terms or spirit of the appended claims.

turn stroke of the head I and causes the elevating of. pins 13 relative tostationary bolster. 8 and thereby the projection of knockout pins 18 into .the mold cavity, causing the molded'article to be freed therefrom.

In order to reset the knockout plate 82 after the ejectionoperation, the operator presses bar Having thus fully described my invention, what I claim as new and; desire to secure by Letters r Patent is:

1. A hydraulic press comprising a stationary bed, a head movable toward said bed for a pressing operation and away from said bed after a pressing operation, a first-:group of hydraulic cylinders provided at one side of said bed, a second group of hydraulic cylinders at the opposite side of said bed, hydraulic plungers reciprocably disposed in said cylinders and connected to said head for reciprocating the latter, means associated with said bed for receiving a first mold portion intermediate said plun'gers, means associated with said head for receiving a second mold portion in alignment with said first mold portion for cooperation therewith, and fluid reser voirs carried by said head and said bed respectively and communicating with each other through at least some of said plungers. 1

2. A molding press comprising a stationary press bed, a movable press head, hydraulic motor means including a cylinder-piston-assembly with i one element thereof connected to said press head and a cooperating element of said cylinder-piston-assembly connected with said press bed, said cylinder-piston-assembly being operable selectively to move said head toward said bed or away therefrom, cooperating mold halves carried by said bed and said head, knockout pins associated with each of said-mold halves, and one pair of rods each oi. which rods is connected to all of said knockout pins, said rods being movable by establishing constant free communication between said reservoir and the lower portion of said cylinder, a reservoir in said head, and a bore lengthwise of said plunger and said piston for establishing free liquid communication between bed, a mold half carried by said bed, a mold half carried by said head and adapted to cooperate with said first-named mold half, a rod carried by said head, a knockout plate carried with lost f motion by said bed and being operable by said said press head and operable in response to the movement of said press head to advance and retract the knockout pins associated with said mold halves in a predetermined sequence.

, 3. A hydraulic press comprising a bed, a head movable towards said bed, a plurality of main hydraulic cylinders carried by said bed adjacent the side faces thereof, main pistons in said cylinders, connecting means connecting said pistons and said head for motion together, auxiliary hydraulic cylinders carried by said bed and arranged adjacent the side faces thereof, auxiliary pistons in said auxiliary cylinders, the means connecting said auxiliary pistons and said head for motion together, means for hydraulically actuating said auxiliary pistons for traversing said head towards said bed, means for hydraulically actuating said main pistons for continuing the movement of said head towards said bed under higher pressure after said traversing, and fluid reservoirs in said head and bed respectively and commuincating with each other through passageways in said connecting means and said main pistons.

bed, a mold half carried by said bed, a mold 4. A hydraulic press comprising a bed, a head movable. towards and away from said bed, tie means fixedly attached to said head adjacent the side faces thereof so as to allow insertion of a.v

tiemeans for moving said head through the intermediary of said tie means, a fluid reservoir in said head, and a fluid reservoir in said bed, said fluid reservoirs being in constant communication with each other through passageways in said tie means and said plunger means.

5. In a hydraulic press, a stationary bed, a movable head thereabove, a, reservoir for hydraulic liquid in said bed, a reservoir for hydraulic liquid in said head, and hydraulically operable plunger means movable in said bed and rigidly connected to said head, said plunger means being provided with a passageway therethrough communicating with both of said reservoirs for establishing constant free liquid communication between said reservoirs regardless of the position of said'head.

6. In a hydraulic press, a bed, a head -there-' above which is movable towards and away from said bed, means forming a hydraulic cylinder in said bed, a piston movable in said cylinder in a direction parallel to the motion of said head,a

plunger fixedly attached to and extending from said piston into fixed engagement with said head whereby said head is moved with said piston, a

reservoir for hydraulic liquid in said bed, means knockout plate.

9. A molding press comprising a bed, a head into knockout position.

rod, a plurality of knockout pins associated with said first-named mold half and actuatable by said knockout plate, and means associated with said knockout plate for allowing said rod to move freely by said knockout plate as said head moves towards said bed and for locking said knockout plate to said rod as said head moves away from said bed.

8. A molding press comprising a bed, a head which is'movabie towards and away from said half carried by said head and adapted to cooperate with said first-named mold half, a rod carried by said head, a knockout plate carried with lost ,motion by said bed and beingmovable parallel to itself in the direction of said rod, a plurality of knockout pins associated with said first-named moldhalf and actuatable by said knockout plate, means associated with said knockout plate for allowing said rod to move freely by said knockout plate as said head moves towards said bed and for locking said knockout plate to said rod as said head moves away from said bed, and means for unlocking said knockout plate from said rod for thereby allowing resetting of said movable towards and away from said bed, a first mold half carried by said bed, a second mold half carried by said head and adapted to cooperate with said first mold half, a knockout plate carried with lost motion by said head, knockout pins associated with said second mold half and adapted to be projected by said knockout plate into said second mold half, a rod fixedly carried by said knockout plate and extending towards said bed, and means on said rod for holding said knockout plate stationary while said head moves towards,said bed to retract said knockout pins from said second mold half. I

10. A molding press comprising a bed, a head movable towards and away from said bed, cooperating mold halves carries by said bed and said head, a plurality of knockout pins associated witheach of said mold halves, and means comprising a pair of members each oi. which is connected to all of said knockout pins, said meni-v bers being operatively connected with said movable head and operable in response to the movement of said head away from said bed to project first the knockout pins pertaining to one mold half into the latter and subsequently to move the knockout pins pertaining to the other mold 'half WARREN R. mm

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