US2011378A - Die casting machine - Google Patents

Description

1935. w. P. SHERMAN 2,011,378

DIE CASTING MACHINE Filed Nov. 24, 1931 4 INVENTOR.

A TTORNEYS.

Patented; Aug. 13, 1935 UNITED STATES PATENT OFFICE 2,011,378 pm CASTING mom Walter P. Sherman, .Jackson Heights, N. Y. Application November 24, 1931, Serial No. 577,019

'1 Claims.

This invention relates to die casting, and more particularly to a novel form of die casting machine,

v The object of the 5 is to provide an improved die casting machine which will be relatively simple in construction and which will operate e'ificiently over an exceptionally long period of useful life for the production of perfect die castings.

More particularly, one object of the present invention is to permit the casting of any metal at any desired pressure,'regardless of the melting point of the metal and of the intensity of the pressure desired. Another-object of the invention is topermit the casting of the desired metal in a pure state, uncontaminated by the gradual solution therein of the metal of the machine parts. Another object of the invention resides in the provision of a die casting machine in which a variety of metals and alloys may be cast, and which permits changing over from one metal to another without difiiculty during the operation of the machine.

In a general way, it may be stated that the foregoing objects are fulfilled by utilizing'in the.

die casting machine a cupor receptacle into 'which or out of which a pressure plunger may be reciprocated in order to eject a single charge of molten metal, previously ladled into the cup, from the cup to the die. Further objects of the present invention are, first, to prevent fiow of molten metal into the die prior to the application of pressure'by means of the pressure plunger; secondly, to insure removal from the cup of any residue of metal not forced into the die; thirdly, to accomplish this desired result without the provision of special ejector means, and more particularly to remove the residue along with the pressure plunger itself; and. fourthly, to separate the solidified residue from the pressure plunger after its removal from the cup. Still another object of the present invention is to facilitate the pouring or ladling of a charge of molten metal into the cup during the operation of the machine.

To the accomplishment of the foregoing and such other objects as may hereinafter appear, my inventionresides in the die casting machine elements and their relation one to'the other as hereinafter are more particularly described in the specification and sought to be defined in the claims. The specification is accompanied by drawings, in which:' 55 Fig. l is apartially sectioned side elevation of present invention, generally,

one form of machine embodying features'of my invention;

Fig. 2 is an enlarged section through the cup and plunger, showing an intermediate position of the plunger during its descent; Q

Fig. 3 is a similar section showing the plunger at the end of its stroke;

Fig. 4 is an inverted plan view of the lower end of the plunger;

Fig. 5 is a partially sectioned elevation through 10 the plunger after its retraction from the cup;

and

Fig. 6 is a perspective view of. the solidified residue after its. removal from the cup and I the plunger. 5

Referring to the drawing, and more particularly to Fig. 1 thereof, the die casting machine of the present invention comprises, generally, a cup or receptacle C, a reciprocable-plunger P adapted to be reciprocated into and out of thego cup C, a die D, and a fiow passage or gate G leading from the cup C into the die D.

In operation, a measured charge of molten metal, sufiicient for a single casting operation, is poured or ladled from a separate heating cru- 2| 'cible, not shown, into the cup C. Plunger P then descends and forces or ejects the molten metal from the cup C into the die D. Plunger P is then retracted and the die D is opened in order to permit removal of the finished casting and the 30 removal of any solidified residue of metal remaining in cup C. The die is then closed, a new charge of molten metal poured into the cup, and the casting operation repeated.

It should first be noticed that the flow passage 3| or gate G is located at an elevation higher than the normal high liquid .level in the cup C. This prevents metal poured into the cup from flowing directly into the die prior to the application of pressure on the metal. The fiow passage between 40 the cup and the diemay take any of a number of .forms so long as at least a portion of the passage is brought to a level higher than the normal high liquid level in the cup. The desired result may be most simply accomplished in the .45 manner shown in the drawing, in accordance with which the die D is located alongside of cup C and the passage or gate G is simply a direct, straight horizontal passage extending from the side of cup C at a-point 2 higher than the liquid level 4, indicated in the drawing.

With this construction, provision must be made to permit fiow of metal upwardly to opening 2 when the plunger P descends.- with this object in view, the sides of the plunger and cup are metal upwardly to the gate.

during its descent, themanner in which the clearance 6 serves to permit free and unobstructed discharge of metal from the cup into the die will be apparent.

After plunger P is retracted from the vcup C, a residue of metal will remain in the cup C, and solidified metal will also fill the gate passage G. It is necessary to remove such residuary metal before the next casting operationcan proceed. For this purpose, ejector pins or a plunger or like reciprocable element may be provided at the bottom of cup C, which pins are forced upwardly after or during retraction of plunger P, and which serve to force the residue of metal at the bottom of the cup upwardly'for removal. At the same time, this body of metal will bu sheared at the point 2 from the metal in gate G. It will further be noted that gate G is given considerable flare or taper, and this is done to insure removal of the metal therein with the casting in the die D.

The die D is of the conventional separable type comprising an ejector die 8 and a cover .die

It). The cover die is fixed to plate i2 of the machine frame and remains stationary. The ejector die 8 is fixed to a movable plate or head I 4 which is arranged for reciprocation on rods I5. In accordance with conventional practice, the mold impression in the ejector die 8 is so designed as to insure retraction of the casting with the ejector die when the latter is moved aWay'from the cover die It]. The conical gate within passage G is moved with the casting in ejector die 8. Near the end of the opening stroke of the die, an appropriate ejector plate and ejector pins may come into operation in accordance with conventional practice, in order to force or free the casting from the ejector die, whereupon it is removed entirely from the machine.

The residue of metal in cup C is preferably forced upwardly before die D is opened, in order to shear the said residue from the-gate G at the point 2. In some cases, particularly with a very small gate opening at the point 2, it may be possible to first open the die D and separate the metal'in gate G from the residue in cup C by a direct pull in tension. This, however, is a relatively undesirable sequence of operation,

first, because it requires undue hold by ejector die 8 on the casting therein, and second, there is no perfect assurance that the point of separation will take place flushwith the wall of the cup at the point 2.

In order to simplify the machine and to dispense with special mechanism for ejecting the solidified residue from cup C, the plunger P of the present machine is preferably provided with an appropriate recess, undercut, or slot suitably shaped to cause the residueof metal in the cup to be retracted along with the plunger. In the particular embodiment here shown, this means consists simply of the transverse key slot 20 formed at the side of theplunger. This slot is preferably located at the point 2 so as to apply.

cated at 46.

' a shearing force directly at the point where it is most needed. The slot is anyway preferably provided on the same side of the plunger as clearance 6, in order to facilitate subsequently separating the residue from the plunger.

It isnecessary toknock the solidified residue of metal from the end of the plunger after each casting operation. With the arrangement so far described, this. may readily'be accomplished by simply hitting the pancake-shaped residue of metal at the bottom of the plunger in the direction of the die D. However, in order to economize in the use of material and fuel, it is desirable to reduce the solidified metal residue to a relatively small amount by accurately measuring the charge of metal poured intothe cup, and in such case the residue at the bottom of the plunger may be too thin to be readily struck. In accordance with a further feature of the present invention, the bottom of the. plunger is provided with a transverse groove or recess 22 extending along a diameter at the bottom of the plunger in the direction of the vertical clearance 6. The recess 22 facilitates the free flow and ejection of molten metal from the cup into the gate when the plunger descends.

.At the same time, when the plunger is drawn upwardly, it exposes a section of m-etal'24 (see Figs. 4 and 5) which may be readily struck to knock the entire solidified residue from the end of the plunger. This residue then takes the shape shown in Fig. 6, and consists of an upright portion 6, corresponding to the vertical flow clearance 6 on the side of the plunger, a transverse portion 20', corresponding to the keyslot 2|], which insures retraction of the residue'with the plunger, a horizontal ridge 22, corresponding to the clearance 22 at the bottom of the plunger, and a flat disclike or pancake-shaped residue 30, corresponding to the actual excess of metal in the cup.

In order to knock the residue from .the end of i the plunger, knockout means are preferably provided consisting of a hammer-like element 32 carrying a knockout bar 34. These elements are reciprocable and preferably adjusted to strike the residue on the end of the plunger when the plunger is in retracted position. The desired movement may most simply be obtained by suspending the elements 32 and 34 on an arm 36 pivoted at-38 on brackets 40 mounted on the machine frame. This knockout mechanism may be operated manually after each stroke of the plunger, or, if preferred, may be operated automatically, and means for automatic operation-is schematically shown in Fig. 1 of the drawing. This means consists simply of a projecting bell crank arm 42 rigidly secured to'the arm 36 and interposed in the path of a collar 44 mounted on plunger P. The position of collar 44 is adjustable, as also are the positions of element 32 and the knockout bar 34. These various members are so relatively positioned that knockout bar 34 is moved against the metal at the end of the plunger at or near the end of the upward'stroke of the plunger. It will be understood, of course, that the knockout means here shown are merely by way of exemplifies.- tion, and that more complex mechanical move ments may be used for the same purpose.

It should be noted that the cup or receptacle C is preferably cut away at one side, as is indi- This facilitates pouring of metal into the cup from a ladle, and reduces the'height to which the metal falls before it hits the bottom of the cup. At the same time, the opposiie side of the cup is given considerable altitude, as is indicated at 48, in order to seal the various clearcup. This feature will be readily understood from an inspection of Fig.2 showing the plunger P just as it reaches the metal, and further showing how the endof the plunger is completely enclosed by the walls and 48 of the. cup, thereby preventing escape of metal. With this arrangement, metal may be poured into the cup rapidly and without requiring undue care or watchfulness on the part of the workman, because the ladle is effectively guided directly into the cup; no appreciable splashing results from pouring; and any slight deposit of metal on the rim of the cup is of no consequence or effect on the operation of the machine.

Plunger P is preferably operated by hydraulic mechanism comprising a piston 50 reciprocable in a cylinder 52 mounted at the upper end of a vertical frame 54. to cylinder 52 through pipes 56 and 58 controlled by appropriate valve mechanism of conventional type. If desired, the area at the lower side of the piston may be diminished to a value permitting of the constant application of pressure fluid through pipe 56, in which case valve control need through the tensiorior tie rod Hi. Pressure fluid is supplied through pipes 66 and 68, and here again,

if desired, the area at the lower side of piston 60 maybesufficiently diminished so; as to make it 1 possible to constantly apply pressure thereto and to use valve control onlyfor the fluid supplied to pipe 68. The valves forcontrolling the operation of pistons .50 and lill'may be'automatically controlled by'mechanical' means-:of-known type, so as to properly interrelate;thegtim'ng and sequence operation of the plunger lfi'and the die D. It will further be appreciated that, if desired, a

relatively small separate hydraulic piston and cylinder mechanism may be used to' operate a knockout bar 34 for .knocking thesolidified residue from the end of plunger P. ,In such case,

the valve for controlling the operation of such an auxil'ary hydraulic mechanism may also be mechanically interrelated to the valves for cyl- ' inders 52 and 62, in order to obtain automatic timing and proper sequence of operation of the various parts of the machine.

The operation of the machine may now be briefly summarized. A measured charge of metal is transferred from a crucible or melting furnace Pressure fluid is supplied only be applied to the supply fluid through pipe to the cup ,0; Plunger P then descends and ejects the metal into die D. Plunger P is retracted, causing the residue of metal in the cup to shear free from the metal in gate G and at the same time retracting the residue'of metal with the plunger. During the upward movement of plunger P, the die D may be opened, the movable portion 8 of the die carrying with it the casting and the conieal'core of metal from gate G. Near the :end of the opening movement of the die, the

casting is ejected therefrom and removed. At or near the end of the upward stroke of p'lunger P,

the solidified residue of metal onfthe end of the same is knocked free from the plunger, after i which it'may be remelted and again used. The

die is then closed, andat the same time a fresh charge of metal is poured into the cup, after to permit plunger. Y

be repeated machine makes it possible to cast any metal atany desired pressure, the metal being heated in a separate and preferably refractory crucible.

The metal being used for casting purposes, may be changed in an instant by. simply beginning to ladle metal from a different crucible. The ladling operation may be accomplished rapidly and expeditiously, and without undue care. No metal is permitted to flow into the die until the entire body of metal is forcibly ejected from the cup into the die, which prevents flaws, porosity, or other defects. The residue in the cup is removed therefroin in a simple and eiiicient manner, and without the provision of special mechanical means with attendant complication and attendant difliculty due to leakage, tolerances, and wear. The residue removed with the plunger is readily knocked therefrom either manually or automatically.

It'will be apparent that while I have shownand descr bed my invention in preferred form, many changes and modifications may be made in the structure disclosed, 'withoutdeparting from the spirit of the invention, defined in the following claims.

. I claim:

1. A die casting machine comprising. a cylindrical pressure cup for receiving a charge of molten metal, a reciprocable but non-rotatable plunger closely fitting said cup and arranged for cooperation therewith, a die arranged alongside of said cup, a diverging gate or =fiow passage extending from the side of the cup directly into the die at an elevation higher, than the normal high liquid level in the cup, the side of the plunger adjacent the gate being cut away from metal from the bottom of ,the cup through the ,v

gate as theplunger descends, and means toremove the solidified residue of metal from'the cup including a transverse key slot cut in said plunger and suitably shaped and located to shear the .gate and insure retraction of the solidfled residue of metal from the cup with theplunger, and I separation of the residue from the 2."A die casting machine comprising a cylindricalpressure cup for "receiving a charge of molten metal, a reciprocable but non-rotatable plunger closely fitting said cup and arranged for cooperation therewith,-a die arranged alongside of said cup, a diverging gate or flow passage extending from the side of the cup directlyinto the I die at an elevation higher than the normal high liquid level in the cup, the side of the plunger adjacent the gate being cut away from thebottom to a point adjacentthe gate in order to provide a clearance permitting free flow of metal from the bottom of'thecup through the gate as 7 the plunger descendameans to remove the solidifled residue of metal from the cup including transverse ke'y slots cut in said plunger and suitably shaped to insure retraction of the solidified residue of metal from the cup with the plunger, and knockout means to knock the solidified residue from the end of the plunger including a reciprocable knockout element arranged to strike the solidified residue in the direction of the aforesaid clearance.

3. A die casting machine comprising a'cylindrical pressure cup for receiving a charge of molten metal, a reciprocable but non-rotatable plunger closely fitting said cup and arranged for cooperation therewith, a die arranged alongside of said cup, and a diverging gate or fiow passage extending from the side of the cup directly-into the die at an elevation higher than'the norm-a1 high liquid level in the cup, the side of'the plunger adjacent the gate being cut away from the bottom to a point adjacent the gate in order to provide a clearance permitting free flow of metal from the bottom of the cup through the gate as the plunger descends, the top or open edge of said cup being cut away at the side 0pposite the gate and die in order to facilitate pouring of molten metal from a ladle into the cup, the relatively greater height of the cup adjacent the gate serving to seal the plunger against escape of metal despite the cut-away flow clearance on said plunger.

4. A die-casting machine comprising a cylindrical pressure cup for receiving a single charge of molten metal, a reciprocable but non-rotatable plunger closely fitting said cup and arranged for cooperation therewith, a die arranged alonginto the die at an elevation higher than the normal high liquid level in the cup, the sideofthe plunger adjacent the gate being cut away from the bottom to a point at the .gate in order to provide a clearance permitting free flow of metal from the bottom of the cup upwardly and through the gate as the plunger descends, said clearance being so shaped as to form a key'slot or recess to insure shearing of the gate and withdrawal of solidified residue with the plunger, and knock-out means on said machine at the opposite side of the plunger and reciprocable toward and from the plunger and so disposed as to strike the solidified residue in a direction toward the aforesaid clearance.

5. A die-casting machine comprising a cylindrical pressure cup for receiving a, single charge of molten metal, a reciprocable but non-rotatable plunger closely fitting said cup and arranged for cooperation therewith, a die arranged alongside of said cup, a divergent gate or flow passage extending from the side of the cup directly into the die at an elevation higher than the normal high liquid level in the cup, the side of the plunger adjacent the gate being cut away from I the plunger having theafores'aid clearance at the top of said clearance, and knock-out means-on said machine at the opposite'side of the plunger and reciprocable toward and from the plunger andso disposed as to strike the solidified residue retracted from the cup by the plunger in a direction toward the aforesaid clearance and key slot or recess.

'6. A die-casting machine comprising a cylindrical pressure cup'for receiving a single charge of molten metal, a reciprocable but non-rotatable plunger closely fitting said cup and arranged for cooperation therewith, a die arranged alongside of said cup, a divergent gate or flow passage extending from the side of the cup directly into the f die at an elevation higher than the normal high liquid level in the cup, the side of the plunger adjacent the gate being cut away from the bottom to a point at the gate in order to provide a clearance permitting tree flow of metal from the'bottom of the cup upwardly and through the gate as the plunger descends, a recess extending diametrically across the bottom of the plunger and terminating at the clearance, and knock-out means on said machine at the opposite side of the plunger and reciprocable toward and from the plunger and so disposed as to'strike the solidified residue retracted from the cup by the plunger at the end of the bottom channel in a direction toward the aforesaid clearance.

7 A die-casting machine comprising a cylindrical pressure cup for receiving a single charge of molten metal, a reciprocable but non-rotatable plunger closely fitting said cup and arranged for cooperation therewith, a die arranged alongside of said cup, a divergent gate or flow passage extending from the side of the cup directly into the die at an elevation higher than the normal high liquid level in the cup, the side of the plunger adjacent the gate being cut away from the bottom to a point at the gate in order to provide a clearance permitting free flow of metal from the bottom of the cup upwardly and through the gate as the plunger descends, a recess extending diametrically across the bottom of the plunger and terminating at the clearance, a key slot or recess extending transversely across that side of the plunger having the aforesaid clearance at the top of said clearance, and knock-out means on said machine at the opposite side of the plunger and reciprocable toward and from the plunger and so disposed as to strike the solidified residue retracted from the cup by the plunger at the end of the bottom channel in a direction toward the aforesaid clearance and key slot or recess.

WALTER P. SHERMAN.

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