US2678480A - Device for delivering metered shots of molten metal for castings - Google Patents

Description

May 18, 1954 J. LAPIN DEVICE FOR.DEL1

VERING METERED SHOTS OF MOLTEN METAL FOR CASTINGS 2 sheets-sheet 1 Filed Jan. 24, 1952 ATTORNEYS May 18, 1954 J. LAPIN DEVICE FOR DELIVERING METERED SHOTS OF MOLTEN METAL FOR CASTINGS 2 Sheets-Sheec 2 Filed Jan. 24, 1952 .5k/'n form'- /rjyas IN VENTOR J0/7n La/o/'n ATTORNEYS Patented May 18, 1954 DEVICE `FOR DELIVERING METERED SHOTS 0F MOLTEN METAL FOR CASTINGS John Lapin, Bay City, Mich., assigner to The Dow Chemical Company, Midland, Mich., a corporation of Delaware .Application January 24, 1952, Serial No. 268,001

3 Claims. 1 lThe invention Vrelates to improved apparatus for delivering accurately metered's'hots of molten metal particularly to a casting device "such as a die casting machine.

`An object of the invention is to provide means fof the foregoing character includinga pipe, having an open delivery end, for conveying by gravity V*flow a succession of metered amounts of molten metal from a source of molten metal, such `as a meltingpot, to the point `of delivery, such as a shot cylinder of a `die-casting machine, without dripping or dribbling from the delivery end after the shot is made. The inlet end of the pipe has a valve means forV regulating the volume, i. e. metering the amount, of `metal entering the pipe for each shot. The deliveryend of the pipe has 'a trap to prevent ingress of vair and maintain the pipe filled with molten metal between deliveries and orince means at the delivery end in `connection with the trap adapted to prevent dripping and dribbling from the delivery end after the said `valve is closed so that the volume of metal delivered. in each shot is precisely metered by the duration of the opening and closing `foi" the said valve.

Other objects and advantages ofthe invention will become apparent as the description of the invention proceeds,

The invention will be more readily understood from a readingrof lthe `following specification and reference to the accompanying drawing showing anexample of the `inventionwherein:

Fig. 1 is a sideelevationpartly in'sec'tionshowing a preferred embodiment of 'th'e apparatus of the invention in position to deliver metered-shots v of molten nieta-Lto a die-casting in'ach'ine.

Fig; 2 is a plan view of a portion of slillig. l.

Fig. '3 is a side `elevation largelyin enlarged vertical sectionI of Tone for-m of the `delivery end of .the apparatus.

Fig. 4 is an end elevation of the "delivery 'end of the appara-tus shown in Fig. 3. l

Fig. 5 is a Jfragmentary View of the plugin the delivery end oi the apparatus shown `in Fig. 3.

Fig. 5 is aside elevation of a modication of the delivery end of the apparatus. A

Fig. 7 is a vertical` section on the line 1-1 of Fig. 6.

Fig. is a fragmentary view oi Fig. 3 showing the orice thereof.

Fig. 9 is a fragmentary view of Fig. '7 showing the orifice thereof.

Referring to the drawing in detail, there is shown a furnace setting l provided withV a heating burner 2 and iiue 3. Shownin the'furn'a'ce `movable cover 9.

setting is the melting pot 4 or metal supply vessel having a rim ii which rests upon the top E of the setting, The melting pot is provided with a cover 'l having a charging opening 3 closed with a re- The side wall l0 of the pot near the bottom H is provided with an opening i2 through which passes the outlet pipe I3, the outside of which is welded or otherwise sealed to the wall of the pot around the opening l2. The end it of the outlet pipe within the pot is rovided with a thick walled elbow i having its open end it extending downward. As shown, the open end is provided with a bevel I1 which forms a valve seat for 'the ball valve I8. rEhe ball valve is carried on the support i9 which is mounted on the lever arm fiii. One end of the lever arm 25 carries a pivot 2i which turns in the bearing 22 secured to the side wall I0 of the pot. The

other end ol the lever arm carries a pivot 23 which turns in the bearing 24 carried by the lower end 25 of the piston rod 26, The upper end 27 of the piston rod extends through the opening 28 in the cover and carries the piston 29. The piston 2Q operates in the inverted cylinder 25 'it which is mounted on the cover l. A compression spring 3l is provided around the upper end of the piston rod and extends between the cover and underside of the piston-and urges the piston upwardly. The upper end 32 of the cylinder above the piston communicates with the pipe 33 which is connected to a source of fluid pressure not shown.

Pipe tti connects with outlet pipe I3 and eX- tends from the wall of the pot through the furnace setting close to the point of delivery of the molten metal from the pot. Both pipe 36 and pipe i3 are preferably arranged to slope upwardly from the elbow i5 at a slight angle to the hori- Zontal, e. g. 1 to 10, so that there is an upwardly inclined continuous passage 35 from the valve seat il in the elbow i5 to the outer end t0 of the pipe, although the pipe 34 may be horizontal or even slope the other Way.

The outer end 3S of the pipe is provided `with a union 3l by which the delivery end means, e. g. 38, are secured to the pipe 34. As shown in Figs. l through 5, the delivery end means 3B comprises a section lof pipe 38 having an upturned end 40 with an external thread 4l thereon by means of which the discharge outlet, having the form of an elbow, indicated generally lby numeral A2, is screwthreadedly thereto secured. The said elbow comprises a body i3 which may be formed in a more or less rectangular oblong block of metal. Through the long axis of the block is formed, the cylindrical bore 44 having the same internal diameter as that of the pipe 39 which may have an I. D. of 1 to 2 inches. Each end of the cylindrical bore lili is roamed out and threaded brought into engagement with the shoulder it so that the wall of the cylindrical bore lill o1" the block and the bore oi the pipe are flush with each other forming a continuous smooth passage. The lower side of the block has a flat face 41 so-formed as to lie in a plane which does not `depart from the horizontal by more than 10. A conical bore is is formed in the block intermediate its ends and extends from the face 4l into the block to intersect the bore fill. The outer and smaller end of conical bore i3 terminates in a circular criiice 49 having a diameter of 1/4 to 1/2 inch. it will be noted that the larger .end of the conical :bore 158 has the same diameter as the bore Il@ which may have a diameter 4of l to 2 inches as aforesaid, The center of the orifice d and the long axis of the bore i8 lie in a vertical plane which also passe-s through the long axis of the bore iii.

A manifold 59 for the distribution of a skin,-

forming gas adjacent to the orice i9 is provided as by drilling a passage into the block perpendicular to the aforesaid plane near the orice and providing -a series of openings di connecting the passage with the space 52 below and adjacent to the orifice. A pipe 53 connects the gas distri bution manifold with a source (not shown) of a suitable skin-forming gas, exemplified later.

Yprovided with an enlarged diameter portion in which a thread l is cut enabling the plug to be screw threadedly secured in the block as shown in Fig. 3. The plug, as in place, streamlines the intersection 58 of the bore ld with the passage 48. The plug being removable also -provides access to the passages through the elbow for cleaning.

The point of intersection 5:9 where the lower side Eil of the bore dit meets the wall el of the `bore A8 is arranged to be at an elevation substantially above the top side 62 of the bore of the pipe section 39 beyond the outer upturned end d. This arrangement may be achieved by bending the outer end lil of the pipe section 39 upwardly V(as shown) so that a horizontal plane 63 passing through the point 59 will be above substantially all the top side d2 of the pipe 39 adjacent to its upturned end et. The plane of the face lil' is machined off" or otherwise formed so as to be in a substantially horizontal lplane (i. e. within of horizontal), as'already indicated, after providing for the aforesaid upturn. It will be notedV that the highest point in the upturned portion of the pipe is within the elbow 122 adjacent to the oriiice 1%.

In the alternate form or outlet orifice arrangement shown in Figs. 6 and "I, the delivery end means 38', already described, are removed at the union 37 and replaced by the alternate form dil.

In this form, a downwardly turned elbow 65 which is secured to pipe 34 by the union 3l' has screwthreadedly secured to it at the downturned end 65 the outlet orice body 61. As shown, this consists of a chamber 68 having a vertical cylindrical side wall S9 and a bottom l0 on the lower end. An internally threaded opening is provided in the bottom concentric with the side wall 59, the axis of `the thread being coincident with the vertical axis of the chamber. Arranged within the chamber is an inverted cup l2 with the cylindrical side wall 13 sealed to the inside 'M of the bottom all around the open end of the cup l2. The closed end 15 of the cup (bottom of the cup 72 inverted) is preferably rounded or dome-shaped on the outside so as to form the convex surface le streamlining the entrance to the annular space il between the outside wall of the cup and the inside wall of the chamber E5. Openings 73 in the side wall of the cup provide communication between the inside 19 of the cup and the aforesaid annular space. The said openings 78 are placed near the open end or" the inverted cup adjacent to the inside le of the bottom l0. Screwthreadedly secured in the said internally threaded opening is the orifice member 80. This consists of a tube-like member having an axial bore 8l 1A; to 1A; inch in diameter, extending from end to end of the member, and an enlarged middle portion 92 which is provided with an external thread E3 by which the Vmember 39 is screwthreadedly secured in the bottom 19. The upper end t4 of the tube-like member extends above the openings '18 into the inverted cup. YThe lower end extends below the bottom lil. The length of the orice member does not exceed 4 to 6 times the diameter of the bore 8l. A gas distributing manifold 9%. in the for-m of a ring shaped pipe is placed around the lower end S9 and openings 8l, in the inner periphery or the nia-nifold 89, are provided which are directed toward the outlet orice 88 at the lower end 95 of the oriiice member 89. A pipe t9 provides an inlet to the manifold sii for a slain-forming gas. The upper end 99 of the chamber is internally threaded and secured by means or this thread to the lower end 55 of the elbow. Pipe 34, and either of the two forms ci the delivery means 39 and 54, may be suitably lagged with thermal insulation 9i and, if desired, an electrical resistance heating element 9.2 may be embedded in it for maintaining the apparatus at operating temperature/ As already indicated, the device is particularly adapted to metering shots of molten metal and delivering the metered shots to a die-casting machine. A portion of a machine of this type is shown in Figs. 1, 2, 6, and '7 in operative relation to the two forms of discharge oriiices 49 and 88, respectively, of the device. The portion shown of the die-casting machine is conventional and consists of a shot cylinder 93 having an opening 94 thereto for receiving the shot and is placed close to and directly below either form of the molten metal delivery means, as indicated in Figs. 1 and 6, respectively. A piston 95 is reciprocally operable in the shot cylinder 93 to force the shot of metal delivered thereto into the cavity of a mold or die. In the usual arrangement of casting apparatus of this kindthe shot cylinder 93 is mounted on a xed platen 96 Vwhich carries one-half 91 of the mold or die.

The other half 98 of the mold or die is mounted `88 (whichever is used) is purged v0i gases.

alloys of magnesium in which the n'iagnesiurn` content exceeds 80 per cent by weight) as in die casting these metals and the operation of the apparatus will be described in connection with metering shots of these metals.

In starting, valve I8 is in the closed position against the beveled valve seat I'I `(as shown) being held by the spring 3|, the upward urge of which exerts an upward pressure on piston 20. This in turn pulls up the rod which raises the lever arm 20, thereby forcing the ball valve I3 onto its seat Il. With this valve thus closed, a supply of molten metal |02 is provided and maintained in the melting pot using conventional procedures `ior preventing atmospheric attack such as the application of a layer oi a iioating saline iiux |03. The depth of `the metal lil? in the melting pot ismade suiiicient to provide a head of molten metal of at least e inches above the outlet orifice 40 or d8, according to the 1nodiiication used. The burner 2 is adjusted to maintain the molten metal |02 at suitable casting temperatures which are ascertainable by trial.

Pipe dand either delivery end means, whichever is used, is maintained atasuitable operating temperature by means of the electrical resistance heating element 02 or by the passage of molten metal when the apparatusA is in full operation. Molten metal` is released from the pot by opening valve |8. is accomplished by applying uid pressure through pipe 33 onto thetop side of piston 20 in amount suiiicient to overcome the upward urge of the spring 3|. The piston 29 is thereby moveddownwardly and this in turn l lowers rod `2li and causes lever arm 20 to swing downwardly and move the ball valve IB downwardly ofi its seat Il. As the molten metal enters the outlet pipe i3 and travels therefrom into; the bore 35 of` pipe 34, it displaces therefrom the air which escapes through the discharge outlet means. In the case of the modiiication illustrated in Fig. 3, the molten metal passes through pipe S0 into the cylindrical bore 44 `and thence through the bore to the outlet orifice 49. In the modification shown in Figs.` 6 and '7, the molten metal from pipe 34 passes through the elbow into chamber 68 and thence through the annular space ll and openings 'I8 into the annular space Hi8. Molten metal passes from the annular space |03 over the upper end 84 of the bore 0I and thence to the outlet oriiice 80. Flow is allowed to continue until the passage from the valve seat Il to the outlet oriiice 40 or Valve I8 is then seated on the seat il by releasing the fluid from the upper end 32 of the cylinder above piston 20 allowing it to move upwardly under the action of the spring 3 I. A shin-forming gas,

such as Soz, B013, EF1, dichlorodiiiuoromethane,

etc., which is capable of forming a tenacious skin on the surface of molten magnesium and the magnesium-base alloys, is released from openings 5| or 8l (whichever form is used) so as to form an atmosphere essentially of skin-forming gas aereas@ adjacent-to` the molten metal atY tlie'i orifice-149.16: 88; respectively.

It will beiobserved that-once the air or' other gas'ihas been purged from the passage from the valve seat l'i to the` outlet orifice 49 or08, which.- ever is used.. and the iiow of metal islstopped by the closure of valve |8,.the saidipassage'remains filled with metal all the way from the valve I0 to the orice i0 or 88, whichever' is' used, anda skin forms on the molten metal at the respective oriiices as shown in Figs. 8 and 9, respectively. In Fig. 8, theskinis shown as |04 over thermetal It retained in bore 40; in Fig. 9, the skin. is shownas |06 over the metal retained in bore 8|.. With the orifice sizes given andv liquid metalhe'ad involved' in the apparatus, the skin is suiliciently strong to retain the metal in the respective passage immediately above it, i. e. the passageV bee tween the outlet orifice 40 and the plane 63 in the case of the modiiication of Fig. 3, or the passage between the orifice 03 and the plane |0`|`y of the upper end 84 of the bore 8| in the caseoi. the modication of Fig. 7,` so that no dripping. or' dribbling` occurs after the valve I8 is closed and atmospheric attack on the molten metal under the skin is substantially prevented. It will be observed also that with either modi`ca tion', the molten metal is trapped in then pipe 34 close to the discharge orifice so that ingress` of air is prevented and there is no danger' 0f the' whole passage from the valve' to the respective oriiice emptying, when valve I0 is closed, in `the event `that vibration lor other inadvertent act' shouldV cause the skin to break. In the modiii-` cationl shown in Fig. 3, it' will be seen that only' a very small volume of metalcan escape in the event that the skin |04 should break while valve`- I3` is closed. The volume of molten metal which might. thus escape. is that which occupies the passage which extends' from the orifice 49` through bore 40 and bore 44 to the level ofthe plane `G3 which is determined by the elevation*- of the point159. In the modiiicaticn shown in Figs. 6 and '7, the volume of molten metal which` might escape in the event that the skin |06 over the metal |00 in the bore 3| breaks is that occupying the bore 8| and the' portion of the space'4 'I0 above the plane |01 whichpasses through the# upper end 84 of the bore 0I. The upper end of theoriiice member 00 thus functions as a trap which traps molten metal in the annular' space'` |062` below the plane |01 and prevents ingressof air into the apparatus beyond the level of the upper end 84 of the bore 3|.

With `the passage from' the valve seat I'I to theoutletA orifice completely iilled with molten.` metal, metered shots thereafter are made byi openingvalve i8 for specific lengths of time ac cordingto the size of the shot desired.-V TheV molten metal thus delivered from the discharge oriiice may fall directly into the opening 94 of the shot cylinder of a die-casting machine as shown.

In using a die-casting machine in connection with the molten metal delivery apparatus, the movable platen 0l? is brought tightly up against the iixed platen Sl and the piston 95 is retracted as shown and then a shot is made by opening valve i3 for a length of time suflicient to deliver the desired volume o metal. The valve I8 is then caused to be closed. Closure of the valve I3 stops the flow of metal from the orice 49 or t3 and thereupon a skin, |04 or |05, respectively, as the case may be, forms over the surface of the metal at the orice 40 or 08, as the case may be, as shown in Figs. 8 and 9, respectively, preventingv dripping or dribbling. As a result, no more than the metered amount of metal enters the shot cylinder 93 at each shot. As soon as the metered shot of molten metal is delivered to the shot cylinder piston 95 is moved (by means not shown) into the shot cylinder 93 so as to force the shot quickly from the cylinder into the die. Therein the molten metal solidies as a. casting. The resulting casting is then removed by retraoting the ram i 90 which moves the platen 99 and die-half 98 away from die-half 91 exposing the casting for removal. After the removal of the casting, the ram is again actuated so as to bring die-half 98 up against diehalf 91 in preparation for the next shot which is made as described. Thus, the operations of delivering accurately metered shots of molten metal may be made repetitiously as desired.

Among the advantages of the invention are dripping or dribbling of molten metal from the orifice is eliminated; oxidation or burning of the molten metal leading to the formation of clogging deposits adjacent to the orifice is virtually eliminated; gas which may be released from the molten metal within the passage from the outlet of the supply vessel to the orifice cannot accumulate in detrimental amount in the passages to interfere with metering; air cannot enter the delivery pipe even in the event that the skin at the orice is accidentally broken allowing molten metal immediately above the orifice to fall out; the apparatus is rugged and allows long troublefree operation; because the passageway from the supply vessel to the orifice remains lled with molten metal during operation and there is no dripping or dribbling from the orifice when the valve is closed, the amount'of metaldischarged from the orifice is precisely metered merely by the length of time the valve is allowed to remain open; the valve, being submerged in the molten metal, is maintained at operating temperature at all times and is not subject to contamination by air.

I VI claim:

l. An apparatus for delivering metered shots of molten metal from a supply thereof to a cast- Y ing apparatus comprising the combination of a vessel for holding a supply of the molten metal; a pipe having one end extending into the vessel to a point near Vthe bottom thereof and the other end outside the vessel at a level between the bottom of the vessel and the operating level of the molten metal in the vessel, the said other end being turned upwardly; a valve on the end of the pipe within the vessel adaptedto start and stop flow of molten metal from inside the vessel through the pipe to meter the shots; a downturned pipe elbow on the upturned end of the said pipe, the downturned end of the said pipe elbow being open and forming an orifice 1A to 1/2 inch in diameter, the periphery of said orice lying in a plane which is not inclined to the horizontal more than 10, the said pipeelbow and delivery pipe forming a continuous passage from the vessel to the orifice, said elbow forming a gas trap in the bore above the orice; and pipe means having an outlet adjacent to the orice below the said plane adapted to deliver a skinforming gas below the said orifice.

2 An apparatus according to claim l in which the passage through the downturned portion of the elbow increases in diameter from the said orice toward the bore of the pipe, and the highest point of the said continuous passage is within the said elbow.

3. An apparatus for delivering metered shots of molten metal from a supply thereof to a casting apparatus comprising the combination ofa vessel for holding a supply of the molten metal; a pipe having one end extending into the vessel to a point near the bottom thereof and the other end outside the vessel at a level between the bottom of the vessel and the operating level of the molten metal in the vessel, the said other end being tilted upwardly; a valve on the end of the pipe within the vessel adapted to start and stop ilow of molten metal from inside the -vessel through the pipe to meter the shots; a downturned pipe elbow on the tilted end of the said pipe; a pipe nipple in the downturned end of the elbow forming an extension of the bore thereof; an orifice tube having a bore 1A; to 1/2 inch in diameter fitted into the lower end of thel pipe nipple and extending upwardly therein the inside of the pipe nipple being spaced from the outside of theorice tube to form therebetween an annular pocket; an inverted cup disposed within the nipple over the upper end of the orifice tube with the rim of the cup extending downwardly into the pocket, said cup having an opening in its side wall near the rim to permit passage of molten metal from the pipe nipple through the side wall of the cup to the orice tube; and pipe means having an outlet adjacent to the orice adapted to deliver a skin-forming gas below the Vsaid orifice. Y Y

References Cited in the file of thisV patent y UNITED STATES PATENTS Number

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