US2512531A - Actuating mechanism - Google Patents

Description

June 20, 1950 1 T. A. RENKENBERGER 2,512,531

' ACTUATING MECHANISM Filed Aug. 28, 1945 5 Sheets-Sheet 1 INVENTOR Haze 14. PENKENBERGEE BY wyea ATTORNEYS.

June 20, 1950 T. A. RENKENBERGEVR ACTUATING ME CHAN ISM 5 sheets-sheet 2 Filed Aug. 28, 1945 uznuzu ATTORNEYS.

June 20, 1950 T. A. RENKENBERGER- ACTUATING MECHANISM Filed Aug. 28, 1945 5 Sheets-Sheet 3 INVENTOR 32.07 67- PEA/KE NAEEGEE.

B 4 l rw ms ATTORNEYS.

June 20, 1950 T. A. RENKENBERGER 2,512,531

ACTUATING MECHANISM Filed Aug. 28, 1945 5 Sheets-Sheet NV E NTOR TY'RZHH 44. PENKE/VBEEGEE.

m5 ATTORNEYS.

June 20, 1950 T. A. RENKENBERGER ACTUATING MECHANISM 5 Sheets-Sheet 5 Filed Aug. 28, 1945 INVENTOR fizzy/4 6'. ,PeA/ms/vesease.

' ATTORNEYS.

Patented June 20, 1950 County,- Pa., assignor to Herman Pneumatic: Machine Company, Pittsburgh, Pa., a corporation of Pennsylvania Application August 28, 1945, SerialQN'o.6131088 (Cl. 60'-54a5)- 3 Claims. 1 I-his invention relates to actuating mechanism. In certain aspects it relates to mechanism for separating molds and: the patterns on which they have been formed. In other aspects the invention relates to actuating mechanism adaptable for use in such separating mechanism and also adaptable for various other uses.

Inthe making Of molds out of sand and other molding materials the molding material is packed against a pattern after which the mold and pattern are separated to enable the mold to be used for forming a casting. Great care must be taken in separating the mold and pattern to avoid damageto the mold during stripping. I here use the term stripping to refer specifically to the relative movement of the mold and pattern from their initial position with the mold lying. against the pattern just until the mold and pattern are out of contact with each other, while separating" is used to comprehend the entire relative movement of the mold and pattern from the beginning of stripping untilrelative movement ceases. The stripping must be accomplished by relative straight line movement between the mold and: pattern without turning or tilting of either. If the mold and pattern turn or tilt relatively to each other during stripping the molding material of which the mold is made is likely to be deformed so that a casting poured in the mold would be defective.

It. is usual in the art to provide mechanism for separatingmolds and the patterns on which they have been formed in conjunction with mechanism for packing the molding material against the pattern so that as soon as the packing step has been completed the mold and pattern may be separated without the necessity of transferringv the assembled mold and pattern from the' packing mechanism to a separating or stripping station at another location. Since ordinarily the mold and pattern are mounted on the packing mechanism it is. necessary in separating them to engage the one which is to be moved, for example, the mold,.at points removed from its center, and ordinarily separation is effected by engaging the flask in which the mold is formed at points spacedabout its periphery to lift it up off of the pattern. It is important to avoid tilting'that the means for lifting the flask and which engage it at spaced points about its periphery move uniformly. If, for example, the flask is engaged at diametrically opposed portions the means engaging the flask and moving it away from the pattern must move with absolute synchronism. This isnota new problem; it has been recognized for many years. andnumerous. attempts to solve it have been.- made.

It is also important-that at the time of initial engagement between" the" separating means and the one of the' mold and pattern whicliistobe moved-for example,- the flask containing the moldtheseparating means move very slowly toavoid a sharp-impact: which might disturb the molding material. therelative movement between the moltl" and the pattern during stripping anduntil themold and pattern are entirely out" of contact with" each other should he very slow. But during; separationathe mold and pattern are moved relativelytto each other until they are spacedapart-a; suhstantial distance so as to facilitatsubse uent separateh'andll l'i'g' of the mold and pattern without danger of their striking oneanother; we avoid waste of time the relative movementof the mold an'cl pattern after stripping should be speeded up; but,- particularly when the-flash" containing the mold is moved to effect stripping and separation; the relative movement should be terminated very gently to avoid shock which mightd'amage' the mold. This problem l il'iewi'se is not new hutis well recognized in theart;

It is also important-to" confine the separating equipment and theactuating mechanismtherefor within a. restrictedspace sin'ce new spacein'-= a foundry is at a premium: Still another desideratumis" to provide'for relatively-rapid movement of the separating means on the return strolie so as to avoid; waste 'of time. Still further, in hydraulically actuated separating? mechanism provision should be made forco'mpensatih'g' upon eachicycle of 'operati'orr-for losso'f flui'clby l'eaka'ge since such loss may result in improper operation ofthe apparatus and consequent relative: tilting of the'mold and patter-xi during stripping, causing damage to the moliii These problems likewise are well recognized in the-art;

All mechanisms for separating molds and the patterns on which they have been formed heretoforeemployed have seem as-I am aware-failed to meet the requirementsof a-- fully satisfactory separating mechanism; Attempts to solve" the primary-problem of straight line stripping have involved the provisibrr oi complicated and' cumbersome equipment expensive to manufacture, costly tokeep up'and extravagant of floor space. No entirely satisfactory" actuating mechanism operating during thevariousportibns" of the cycle at the relative speeds desired? hasrb'een" provided. In various other respects the best separating equipment devised" by those skilled in the art has been found wanting;

I provide mechanism for. separatingimolds and the patterns-on whichftheyihaverheen formed'and actuating mechanism tiierefiir which fbi thefirst time so far as I am aware satisfactorily solve all the long existing problems above referred to. My separating mechanism insures at all times accuratestraight line stripping, and accomplishes separatifin great Eefliciency' jof' time. The mechanism is compact and highly economical of floor space. It is preferably hydraulically actuated and provision is made for automatic compensation for leakage of fluid, insuring accurate operation upon each cycle.-; .My.. mechanism is fully automatic and elimin to the human element in operation.

I provide mechanism for separating molds and the patterns on whichthey have been formed comprising means for r'rioViiigoxie' of'a'mold and the pattern on which it has been formed relatively to the other thei'eof to separate the mold and -pattern, .said-. meahs comprising a smaller a ar er cylinder arranged in tandem, a piston; fittillgjii 'the smaller j -cylinder and havin an extension;extending' ;into the larger cylinder, -;.a pistonfltting infthe larger cylinder carried by the extension, the extenslonland the larger cylinder defining .anannulajr space whose cross- ..sectional..ar ea is substantiallyequal to the cross- ..sectional area of..'thej, smaller cylinder, outlets from vthe-.arpjrflaf.spa ce and the smaller cylinder, .means fenmoyingthe, pistons to discharge ;-fluidfronrthe annularlspace and the smaller ..cylinder; ,through;the. respective outlets, the rate the rate .of -.discharg e ofifluid from the smaller ecy de substan l :e means operated-hythefluid discharged from the annular-spaceandthe fluid: discharged from the f smal e -l y eeetsena et dr said of the -mold; and pattern. 3 Iadesirablyiemploy a liquid receptacle, a,spurce; f compressed gas, a cono romlthe .sqili i i f n ed gas to the liquid receptacle, a .plura1ity of cylinders each having a piston therein and a fluid outlet, the "cylinders having -substantially equal effective cross-sectional areas, said pistons being connectedtogether for moyernentas a unit, a connection I -from said liquid receptacle tosaid pistons whereby liq i .gompressedbysaid gas advances said ..appended 'claims. .Other. details, objects and ad- :vantages jof the inventio'n will become apparent as the followingdescription, of a present preferred embodimentt reefpr e d -I,n-the accompanying drawings I .have shown a present preferredenibodimentlof the invention, in which:

: E u 1 view, taken on.

vertical I cross-sectional elites I-I ofFigures 2 and 3,

.through actuating'linechanism which I prefer to v v employ for actuating my mold and pattern sep-' arating'mechanism; a I

' Figure Z is" elevationalview, partly in ver- "tical cross section, of the actuating mechanism ,showninFigurel;

me h sm-sum WW2; 5,

'4 is a viewpartiy in elevatidn and partly n assi aemaaw w'ie th in central vertical cross section on the line IV-- IV of Figure 5 of mold and pattern separating mechanism;

Figure 5 is a top plan view of the mechanism shown in Figure 4;

Figure 6 is a diagrammatic view in plan showing the hydraulic system;

Figure '7 is a diagrammatic view in elevation showing the hydraulic system; and

Figure 815 a detail cross-sectional view through the unloading valve used in the actuating mechanism.

Referring now more particularly to the drawings, there is provided a liquid receptacle 2 adapted tocontain hydraulic liquid such as oil and to receive also gas under pressure, such, for example, as compressed air, the receptacle 2 being adapted normally to lbeclosed so that the compressed air is efiective for compressing the oil which serves as the actuating fluid of my mechanism. In the bottom of the receptacle 2 is a vent normally closed by, a plug 3. Connected with the top of the receptacle 2 and communicating with the interior thereof is a conduit 4 leading to an unloading valve 5 shownin cross section to enlarged-scale in Figure 8. The unloading valve 5 comprises a casing 6 with which the conduit 4 may be integral, the casing being closed at the left hand end viewing Figure 8 by a plate 1 threadedly receiving an air line 8. The air line 8 extends to a source of compressed air, as, for example, any ordinary air compressor, a manual control valve 9 (Figure 7) being disposed between the air line 8 and the source of compressed air and being operable to admit compressed air to the valve 5 or to shut off the supply of compressed air as desired, and, when the supply of compressed air is shut ofi, to open line 8 to the atmosphere. As will presently appear, manual opening of the valve 9 actuates my apparatus to separate a mold and the pattern on which it has been formed, the apparatus functioning automatically to the end of the separating movement. Likewise when the valve 9 is closed the efiective elements of my apparatus automatically return to their initial positions ready for repetition of the cycle.

Referring to Figure 8, the'u'nloading valve 5 contains a valve element l0 movable as a whole between a seated position'at the rig-ht hand extremity of its travel to close the exhaust passage I l and an unseated position at the left hand extremity of its travel which allows communication between the exhaustpassage H and the passage [2 communicating with the liquid receptacle 2.

'The valve element I0 is of spider formf'containing a Ibore having a portion I3 of relatively great transverse dimension and a portion M of relatively small transverse dimension. Operating in the bore [3 is an inner valve element I5 adapted to cooperate with a plate l6 having therein an opening 11. A spring ['8 urges the inner valve element 15 toward the left'viewing Figure 8 to seated position against the plate it to close the piston and held in adiusted positiombp w nch-Ni,

theaopenmg I and throug-h passagesiim the 'snideralike valve elementm to" the passage. I 2 and: thence into the liquid: receptacle. 2 During operation of the mechanism: compressed air? con the-spring l8. Duetothe fact that macaw-elemerit l'il lia s a greater areaat its left hand: end thana'ti its right hand end exposedttm the: air; in the passage- 12 the compressed air in the: liquid receptacle z immediately moves the valfvleielement "l b .t'o" theleft, opening-the exhaust" passage-H.

The 'action of the unloading valve iisivery test and the exhaust passage l1 is large so -thatthe air pressure in the liquid: receptacle: 2: is: relieved virtually instantaneously upon the closing-f the valve Thee-liquid receptacle 2 is mountedsomandifast'en'ecl by" bolts It to an-underlyingi supporting structure including a relatively small-vertical-cybinder- Zll and' a larger vertical-cylinder 21 coaxial with th'e cylinder 211 The structure'rhas -amasmunicates through an opening: 23 with-'the liquid receptacle 2. A base" plate 24 is bolted-1 to." the structure bybolts' 25;- Thebase' plate? i'lha sia passage 26 which communicates with theapassage 2'2 and. also with a, central upwardly extending threaded opening 2T in the base: plate-which threadedly receives avertically extending speed controlmember having therethrough a bore 29 communicating with the passage- 26 and with openingstnin the wallof thespeed' control member 28 near the topthereof; Boltedztor the-:top of' 'the'speed control member- 2-8 by bolts'i3 la .is a plate 32 whose edges project outwardlyibeyond the surf'ace of the speed control member as-zshown a passage 34 is for-med within the-wall: or. the

oylinder zll i and opens at its bottom int thev em inder- -Z I- Alpa'ssage 35 extends between thaliquid receptacle 2 and the passage 34-; A passage 35 extends-between the liquid: receptacle-landithe cylinder 20% A vent in theupper end" of therpa'se sage 3 4' is-closed by a plug 31. oilI 1mg: 38 communicates with the passage 34' nearithe'lower end thereofi Connected with-the: top-of the' liquid receptacle 32 and} extendingdownwardly thereintoi .a

stepped cylinder 39 having an upper bore" 411 of relatively large diameter anda lower bored-l of relatively small diameter. A; piston fl -ha's an upper portion fitting the upper bore 40 and -a lower portion fitting the lower bore-4|; Theupperbore' is closed 'by a top-plate -43 ilie1d in place b'yibol'ts '44; Threaded through the" plate 43 isair line 45*which connects with theair line't through a T 45. A globe'valve- Wisdis- "sustain the line 8 between the unloading valve -5 and the-T 46 When the valve -9 is openedconrpressed airis admitted t'o-the bore d-fl-through: "theairf-line -45 as wellwasto the'liquid'reeeptacle z through the unloadingvalve 5-.- fUpwardmovement ofthe piston fli stlimited a set screw 48" threaded into thez-toptofithe reiscrew 5B isn't-plunger: 5| whichioperate 6. connected with the.:bottom-: of; the'pistongthrough .J in gumer tioal guide ih The'plunger 51- urged upwardlyby av compression coil spring 53:: hearing between; an enlarged head 54*- on. theplunger; and the ltopi oi the guide. 52; A passage 55 extends through the-'baseofrthe guide 52* and communiicates' wlth thehore thereof at its bottom. The passagessfi -and 36 open: upwardly into the bore theguido: 5'2 when; the'plunger 5 l'; in its:-upper' 'positionas: shownin'Figure; 1 free com-- munication is permitted between: the interior: of thealiquid receptacle2 and; each of the, cylinders 20 and 2ls. When; however, the'plunger 5 issi-n its-lowermost posit-ionit. closes the passages: 35 and 36 where they open. into the bore of the? ide 52 thus disestablishing. communication be, thei -liquidi receptacle 2 and; the respective cylinderstflh it.

Whenthe valve-.9 is. open the oil in the re.- ceptacle 2 is: compressed: by the air entering through the air line Bland at the same time; the piston 42: ismoyedidownwardly by the air in the air line 45 to hold the plunger 5| in its; lowermost? position and. close the" passages. 35- and- 36. Whenthe valve 9 is closed: the spring 53 moves th'e' -plung'er- 5| and the. piston 42-1upwardly to. the position. shown in. Figure 1, reestablishing. com}- m umcation between the: receptacle 2 and the respective cylinders 20 and; 245.. The purpose of this-mechanism is: to-com-pensat'e for any leakage oi oil from-the cylinders 20- and 21 during the primary operation of theaotuating mechanism which" will: presently be described; At the: conclusion of each cycle of. operation communicatio'n is establishedabetween. the receptacle 2' and each of the twocylinders 50' that any oil; which has leakedout: during; the preceding cycle is replaced.

In the cylinder 20 operates a piston 56. The piston: 56: is axially elongated as shown at 51, projecting downwardly and terminating, ins, pistom58 lifting and.. operating withinthe cylind'erZ L Thus the pistons 56' and 5,8 are-inte rally connected: together to operate as a unit. annular space 59 is: formed within the cylinder 21 and! outside=thedownward extension 51 of the piston: 56.. The partsrare so proportioned. that the cross-sectional area of the annularispace Sal's-equal to the cross-sectional area oi the oylinderZlL Aringafitl surrounds thelower end of theextension: 51' and upon upward movement of. the pistons engages. a stop. 6| integral with the cylinders to limit thestroke of the. pistons The piston 56f-has a) central vent opening 62 closed bylapIugIW.

The piston 58 has a circular central opening W through which the speed control member--28 passes The speed controllmember 28has alower cylindrical portion: 65 of maximum diameter slightly smaller than the opening- 64 so as always to?provide a passage between the speed control member l -wand thepe'riphe'ry-ot the" opening. 64. The baseplate 24 has an annular depression 66 communicating withthe passage between the speed ontrol member 28' and" the periphery of the" opening 64. The base plate fil -alsohas-amothe'r annular depression- 61 surrounding the annular depression 66. The depressions 66' and 61 are connected together by a series of radiating channels 68; I

The speed control-member 2 8 has above themelindrical portion 65 a cylindrical. portion fiaof somewhat smaller diameter than". theicylindrical periton tis ahdladiacentitaurpe :endianotherzcae ing H with the top of the cylinder 21?.

ceding cycle.

cgarzgssi lindrical portion 10 ofthe same diameter. as the cylindrical portion 69.- Intermediate the cyline drical portions 69 and H3 are two frusto-conical portions H and F2. The lower frusto-conical portion H tapers gradually from the diameter of the portion 59 to a minimum diameter 'at its upper extremity at it and the upper frustoconical portion 12 tapers gradually from the minimum diameter at E3 to the diameter of the portion 16. trol member 28 nd normally seats upon the upper surface of the piston 53 ooaxially with the opening 64. The internal diameter of the collar 74 is very slightly greater than the external diameter of the portion 69 of the speed control member 28 so that when the collar 14 is seated on the piston 53 and the partsare in the posi tion shown in Figure l a very restricted passage is provided between the collar and the speed control member. will presently be described the collar is is lifted from its seat upon the piston 53 and when this occurs a passage of relatively great cross-sectional area is immediately opened between the interior of the hollow piston and the depressions B6 and 6! and the channels 58. The piston 56, the piston 58 and the extension 5'; joining these two pistons form in effect a hollow duplex piston with the speed control member 28 projecting up into the interior thereof.

An oil line it communicates with a passage Hi which in turn communicates through an open- Vents in the base plate 2d are normally closed by plugs 18 and 79, respectively.

The actuating mechanism which has been described is for the purpose of delivering oilsimultaneously through the two oil lines 38 and 75 at equal rates. The manner in which this is accomplished will noW be described. The oil lines 38 and T5, the cylinder 29, the annular space 2! and the passages 3 and 35 are filled with oil. Likewise the receptacle 2 contains oil to a level somewhat below the top thereof and oil fills the passages 22 and 25, the bore in the speed control member 23, the space within the hollow composite piston 5l3-'-lil53, the passage between the'speed control member 28 and the periphery of the opening the depressions t8 and El and "the channels 68. Normally when the mechanism is not operating the valve 9 is closed. When the valve 9 is closed the plunger 5! is in its uppermost position as shown in Figure 1 allowing communication between the receptacle 2, the cylinder '20 and the annular space 59 so that oil fromthe receptacle may flow into the cylinder, Eli and the annular space 581 to replace any'oii which has escaped by leakage or otherwise during the pre- Sincethere is no pressure upon the oil in the receptacle 2 the oil in the oil lines :38 and 55', beingunder pressure from the opporsite ends of those lines, respectively, as will presently appear, backs up into the annular space 59 and the cylinder E l, respectively, and the piston 55l58 moves to its lowermost posi- .tion. After the parts have moved to theposition shown in Figure l the collar 5 settles upon the piston 58 and the mechanism is ready for operation. Its operation. is effected simply by opening the valve 9. 7

Immediately upon opening of the valve 9 compressed air passes through the lines a and 45 into the receptacle 2 and the bore ll respectively.

The plunger 51 is moved to the bottomofits A collar M surrounds the speed con- Under certain conditions as 58 both pistons risetogether.

from the receptacle ,2 through the- passages 22 and 26 up through the hollow bore of the speed control member 28 and out through the openings 30 into the hollow piston and thence downwardly ioutsideof the speed control member 28 and nular space 59 oil is delivered simultaneously through the oil lines 38 and i5 atthe same rate.

The initial upward movement of the pistons is very slow due to the fact that the oil forcing the pistons upwardly has-to pass through the very restricted opening between the portion 69 of the speedcontrol member 28 and the collar 14. However,v after the pistons have moved upwardly to the point at which the collar 74 is opposite the lower frusto-conica1 portion ll of the speed control member 28 the. passage between the speed control member and the collar gradually increases in area and as such passage increases in area the rate of flow of oil therethrough increases and hence the speed of upward movement of the pistons increases. This increase in speed continues until the portion E3 of smallest crosssectional area'of the speed control member 28 passes within the collar it, after which the upper frusto-conical portion 12 of the speed control member 28 enters the collar, gradually reducing the area of the passage between the speed control member and'the collaruntil the upper cylindrical portion "ill of the speed control member enters the collar, and consequently gradually decreasing the speed of upward movement of the pistons, whereafter movement of i the pistons is at the same .very slow rate as at the beginning of the stroke when the portion 69 of the speed control member was passing through the collar.

.- As will presently appear, the reason for controlling the speed of the pistons as just described is to correspondingly control the rate of delivery of the oil through the oil lines 38 and 15 toin turn correspondingly control the rate of movement of the mechanism being actuated, in this instance mechanism for separating molds and the patterns on which they have been formed.

Initial slowmovement of such mechanism is desired to prevent shock which might damage'the mold when the lifting mechanism presently to be described engages the mold. The speeding up of movement thereafter is simply to save time. The slowing down 'of movement near the end of the stroke is to avoid shock to the mold as. it comes to a stop which might cause damage to it;

The entire operation of the actuating. mechanism is automaticin response to opening of the valve 9., The speed of movement of the pistons and hence the speed of delivery to the oil is or-- dinarily controlled first at low speed, then gradually increasing in speed, then gradually .slowing down and finally coming toa gentle stop.

when the parts are to be returned to their ini- ;.tial position the valve 9 is closed. Immediately .the plunger 5! rises, establishing communication between the receptacle 2 on the one hand and .thecylinder 20 and the annular space 59 on the other hand. The pressure above the oil in the receptacle 2 is relieved so that oil may pass up- -.wardly; into the receptacle. dines-1.38: nd I5- is underpressure ;,th .t 0i1- flovqs As the oil in theoll amgpei back :into the annular space 59 and the -.cylinder '29, grespectively, forcing it-he hollow piston 56 57- 58 "downwardly. '.As the i-piston 58 moves downwardly Cthev oil :therebelow ypasses upwardly through the opening wfizllrabout the speed control member all. Such upward passage of oil unseats the collar M, which rises, immediately providing a passage 'of much greater area for upflow of oil vthan .the passage provided .for downflow during the preceding stroke in the opposite direction. Thus downward movement of the pistons is at amaterially'faster rate-than upward movement thereof. The collar M is prevented from rising above .the top .of "the .speed {control member :28 :by the projecting iperipheral portion 33zjof'the;plate 32. .Theoil entering the :hollow piston 5.6''5|-.58 flows downwardly through the bore in etherspeed ..control.member229,thencei1aterally :through the passage .26 and thence upwardly throughthe passage .22 .into the :receptacle 2. When the hollow piston .5fi.--5'l'-'+58 reaches the bottom -'of its stroke .(the position shown in Figure '21) ithezmechanism .is .ready ifor the succeedingcycle of :operations.

"Referring now .more particularly to Figures 4 and there iiS shownamold packing mechanism designated generally by reference numeral {89 which is bolted .to .a concrete .foun'dation 8| by bolts 82. The mold packing mechanism may, for example, be a jolting' machine of the Herman Pneumatic type comprising a control valve 93 and a movable head 85 upon which is mounted a pattern stool 85 which carries a pattern (not shown). The flask containing sand or other molding material is disposed over the pattern. The jolting machine packs the molding material against the pattern. The jolting machine is well known.

Mounted in the concrete foundation are opposed cylinders. Since these cylinders are identical only one of them will be described, that description sufficing for both. The cylinder comprises a base portion 81 to which an upper portion 88 is bolted by bolts 89. The diameter of the portion 81 is greater than that of the portion 88. The oil line 38 is let into the cylinder portion 8! through a passage 90. Similarly the oil line 75 is let into the cylinder on the opposite side which, as above stated, is identical to the cylinder being described. Disposed in the cylinder is a piston 9| which fits into the upper portion 88 of the cylinder. The cylinder is provided with a vent closed by a plug 92. At its upper end the cylinder is provided with packing 93 held in place by a packing gland 94 sealing against the piston.

Each piston carries a plate 95 to which is connected a bracket 96 carrying a pair of parallel horizontally extending arms 91. In the end of each arm 91 is threaded a bolt 98 maintained in adjusted position by a nut 99. A guide rod I09 operating in a guide |9| assists in guiding the piston. A sand guard I02 protects the piston and cylinder from sand from the mold.

The two pairs of bolts 98, one pair on each side of the mechanism, as shown in Figure 5, are adjusted so that their upper surfaces lie in the same horizontal plane. These four bolts are flask engaging members and when the two pistons 9| are in their lowermost position as shown in Figure 4 the four bolt heads underlie the rim of When oil passes through the oil lines 38 and I5 into the cylinders containing the pistons 9| those pistons are caused to rise since the oil acts 1 0' againsttheunder-surfaces thereonthis beingprovided for by :recess I93 in :the bottom of each cylinder whichis connected with the-passage 90 and radiallchannels I94 communicating with the annular space .105 between the base portion 81 of 'Ilhe stripping'is accomplished at ver-ylow speed to avoid any possible damage to the mold. After completion ,of stripping the upward movement of the :flask carried by the "bolts :98 increases and as the flask nears the upper limit of its movement its speed decreases until it .is brought gently .to rest. This 'is accomplished by the actuating mechanism -.fully described and explained above.

After the flask-comes to restat the end of the upward movement of :the pistons .-9'| it :is removed from the bolts 98 whereupon the pistons 9| are lowered .in their cylinders to their lowermost position :as shown in i-Figure 4. When the valve 9 is closed the oil flows back from the cylinders containing the pistons 9| through the oil lines 38 and 15 to the annular space 59 and the cylinder 20, respectively. This reverse oil flow is caused bythe downward movement of the pistons 9| due to gravity, the pistons and the superstructure carried thereby being of sufficient mass to cause the reverse oil flow. Both the pistons 9| and the hollow piston 56--5'|58 are urged downwardly by gravity. However the downward movement of the later piston is due primarily to the backflow of oil through the oil lines 38 and 15 caused by the downward movement of the pistons 9|.

While I have shown and described a present preferred embodiment of the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied within the scope of the following claims.

I claim:

1. Actuating mechanism comprising a liquid receptacle, a source of compressed gas, a connection from the source of compressed gas to the liquid receptacle, a plurality of cylinders each having a piston therein and a liquid outlet, the cylinders having substantially equal effective cross-sectional areas, the pistons being connected together for movement as a unit, a connection from the liquid receptacle to the pistons whereby liquid compressed by said gas advances the pis tons simultaneouly in the cylinders to discharge liquid through the respective outlets at substantially equal rates, connections from the liquid receptacle to the respective cylinders, means adapted to close said latter mentioned connections but urged to inoperative position and means connected with the source of compressed gas operable when the liquid in the receptacle is under compression by said gas rendering said first mentioned means operative to close said connections.

2. Actuating mechanism comprising a liquid receptacle, means for placing liquid in the liquid receptacle under pressure, a plurality of cylinders each having a piston therein and a liquid outlet, the cylinders having substantially equal effective cross-sectional areas, the pistons being connected to inoperative position and means connected with the means for placing liquid in the liquid receptacle under pressure operable when the liquid in the receptacle is under pressure rendering said first mentioned means operative to close said connections.

3. Actuating mechanism comprising a liquid rcceptacle, means for placing liquid in the liquid receptacle under pressure, a plurality of cylinders each having a piston therein and a liquid outlet, the cylinders having substantially equal 12 mentioned connections and means for rendering operative said last mentioned means not later than when said means for placing liquid in the liquid receptacle under pressure becomes operative to close said connections.

TIRZAH A. RENKENBERGER.

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

UNITED STATES PATENTS Number Name Date 635,848 Dutton Oct. 31, 1899 831,165 Taylor Mar. 10, 1908 961,702 Lewis June 14, 1910 1,010,000 Snyder Nov. 28, 1911 1,389,300 Gasche Aug. 30, 1921 1,517,798 Nesham Dec. 2, 1924 1,626,225 Campbell Apr. 26, 1927 1,661,621 Pieper Mar. 6, 1928 1,707,781 Blanchard Apr. 2, 1929 1,877,102 Whitesell Sept. 13, 1932 2,060,854 Carroll Nov. 17, 1936 2,206,459 Hagemeyer July 2, 1940 2,252,418 Shelley Aug. 12, 1941 2,380,575 Brown July 31, 1945 2,381,664 Hansen Aug. 7, 1945

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