US1954775A - Die-casting machine - Google Patents

Description

A ril. 10, 1934. w. J. DURING ET AL DIE CASTING MACHINE I FiledJan. 5, 1931 3 SheetsSheet l VEIYTORS April 10, 1934. w. J. DURING El AL QDIE'CASTING MACHIN 3* Sheets-Sheet 2 Filed Jan 5, 1931 .V .N w I I! I I I l f l r a 5 |..1 5 NV T M n J v w a n i w I. I H 3 -m h I 1 i l l .a Q n M s w EM 3 N a km w 833 3 3 Wm 5% 9 l v. WW I w a Q Q .2 &, av w R E R on Q h N N l| I ll 1' l Il I! W PM P b\ ll 2k www 3 II mfik/ Q Q U NW i E, NM NM, 0 .k QWM. s w 3M MMQM. MM, K .1 .3 5 V 6 April 10, 1934. W. J. DURING ET AL 1354,775-

DIE CASTING MACHINE I Filed Jan. 5. 1931 3 Sheets-Sheet 3 u a an u 5 n v a I, I. 1 n M M MW Z k 11% 1 6 i A 1 m w P TM\ a a w M ,v M 8 \V m y z 3% x a z h fl \M a. g. A: U W a M w x \N \H\ Patented Apr. n10, 1934 DIE-CASTING MACHINI' William J. During, Syracuse, N. Y.,- and Nathan Lester, Cleveland, 'Ohio, assignors to Precision Castings Company, Inc., Syracuse, N. Y., a corporation of New York Application January 5, 1931, Serial No. 506,616

6 Claims. (Cl. 22-68) This invention relates to die-casting machines and pertains more particularly to an apparatus adapted to produce aluminum castings, although we desire it to be understood that this device can readily be used for other metals such as iron, brass, etc.

One of the objects of this invention is to produce a casting machine having a novel and improved means of feeding the molten metal from the crucible or melting pot into the plunger box.

Another object is to provide simple and positive means for forcing the molten metal into the die cavity under very high pressure.

A further object is to produce a machine of the above mentioned class which is compact, rigid and durably constructed, and which is rapid and positive in operation.

Other objects and advantages relating to th form and relation of the parts thereof, will more .fully appear from the following description taken in connection with the accompanying drawings in which: I

Figure 1 is a plan view, partly broken away, of 'a die-casting machine embodying the various features of this invention.

Figure 2 is a longitudinal vertical sectional view, taken inthe plane of the line 2-2, Figure 1.

Figure 3 is an enlarged transverse detail sectional view taken on line 33, Figure 2.

v Figure 4 is an enlarged longitudinal vertical sectional viewthrough the control valve mech-- anism, taken on line 4-4, Figure 2.

Figure 5 is a detail sectional view taken on lin 5-5, Figure 4.

The machine, as illustrated in the drawings, consists of a bed plate 1 having a suitable furnace 2 mounted at one end thereof. The furnace 2 is shown as having one. side thereof open for receiving therein a melting pot or crucible 3. The open side of the furnace is shown closed by a suitable door 4 which is hingedly connected at 5 to the furnace 2.

The upper end of the furnace'chamber as 2' is closed by a cover plate 6 which may be secured to the furnace 2 in any'well known manner, not necessary to herein illustrate. A fixed die-supporting frame 7 is positioned above the cover plate 6 and secured thereto by bolts or screws 8 which pass through suitable openings provided in lateral flanges or legs 9 provided at each side of the supporting frame 7 and screw-threaded into the furnace cover plate 6.

The supporting frame 7 in this instance, is L-shaped in cross section, with one leg as '7 thereof extending upwardlyin a vertical plane for supporting one of the die sections as 10" of a sectional die member 10 which may be secured to said leg '7 in any manner well known to those skilled in the art.

The other or horizontally disposed leg 7 of the supporting frame 'l extends rearwardly from the vertically disposed leg 7' in spaced relation to the furnace cover plate 6 and has the outer end thereof provided with a vertically disposed downwardly extending flange 11 adapted to form an end plate for a cylinder 12. The other end of the cylinder 12 is also provided with an end plate 13, and the cylinder 12 and end plate 13 are secured together and to the end plate 11 of the supporting frame 7 by means of a plurality of, in this instance six, screws or bolts 14 which pass through suitable openings in the outer end plate 13 and are screw-threaded in the end plate 11.

Each of the end plates 11 and 13 is provided with a port 15 and 16 respectively which are in communication with the interior of the cylinder 12 and are connected by corresponding conduits 17 and 18 with. a' suitable control valve as 19, which will hereinafter be more fully described.

A piston 20 is mounted for longitudinal reciprocative movement inthe cylinder 12 and is connected to one end of a piston rod 21 which extends outwardly through a suitable opening 22 provided in the end plate 11 and has the outer end thereof connected by a link 23 to the outer end of a plunger 24.

The plunger 24 is mounted for longitudinal reciprocative movement in a plunger box 25 which is secured to the underside of the supporting frame '7 by means of a supporting bracket 26 which extends transversely across the underside of the plunger box 25 and which is secured to the supporting frame '7 by means of bolts or screws 27 which extend through registering openings provided in the bracket 26 and plunger box 25 and are screw-threaded in said frame, as illustrated more clearly in Figure 3.

The bracket 26 is also employed to secure a feeding tube 28 to the underside of the plunger box 25 in registration with a passage 29 provided in the bottom wall of the plunger box 25 in the following manner: The bracket 26 is provided with a longitudinal T-slot 26' which extends across the upper face thereof and is adapted to receive therein the upper end of the feed tube "28 which is provided with an outwardly extending substantially rectangular flange 28'.

The feeder tube 28, in this instance, is conical in longitudinal cross section, with the larger end thereofpositioned at the bottom. The tube 28 extends downwardly 1m the plunger box 25 through a suitable annular 'ipening 6' provided in the cover plate 6 and which is positioned substantially over the center of the furnace chamber 2'. The lower end of the feeder tube 28 extends some distance into the furnace chamber 2' and, is positioned in the crucible 3, as illustrated in Fig! 11. 3? 2.

The plunger chamber 25 of the plunger box 25, in this instance, is a substantially rectangular slot in cross section formed longitudinally of the plunger box 25 in the upper face thereof.

The side walls of the chamber 25 are tapered upwardly and outwardly from the bottom of said chamber for receiving therebetween a similarly constructed plunger 24. The upper open face of the plunger chamber 25' is closed by the adjacent portion of the supporting frame 7 and also by the fixed die section 10' while the inner end of said chamber is closed by :the movable die section as 10".

The link 23 is removably connected with the plunger 24 and also with the piston rod 21 so as to facilitate the assembling of these units. The plunger 24, when in its normal outer position, has the inner end thereof positioned in registration with the outer edge of the passage 29 so as to permit the free entrance of the molten metal into the plunger chamber 25'. The forward end of the chamber 25 is in communica tion with a gate or sprue forming passage 30 provided for the die 10.

It will be noted that as different width die sections 10' and 10 are used, that it will be necessary to use a correspondingly constructed plunger box 25 which may be easily and-quickly substituted for any other plunger box by the removing of the screws 27.

In the supporting frame 7 is provided a passage 31 which has the outer end thereof connected by a suitable conduit 32 with a control valve 33 which will be. hereinafter more fully described. The'inner end of the passage 31 is in.

communication with the upper portion of the plunger 24 and is connected with the chamber 25' by means of a relatively small passage 24" flange 34 formed at the upper end of the vertical leg 7' of the frame 7, said screws having their inner ends contacting with the upper end of the die section 10.

The movable die section 10", in this instance, is secured to a movable die-supporting plate 35 which is substantially rectangular in face view and has each corner thereof provided with suitable openings 35 for receiving therethrough a respective tie rod 36 for slidably supporting said die plate thereon.

The rod 40 has slidably mounted thereona tubular bracket 43 which isv connected by a rod 44 to the lower. end of a downwardly extending arm 39' formed integral with the lower face of the cylinder plate '39. To the outer face of the cylinder-supporting plate 39 is secured a cylinder 45 and two head plates 46 and 47, said cylinder and head plates being secured together and to the cylinder 39 by means of a plurality of, in

this instance six, bolts or screws 48 which pass through registering openings in the cylinder heads 46 and 47 and are screwthreaded in an outwardly extending projection 49 made integral with the outer face of the cylinder plate 39.

Each of the end plates 46 and 47 is provided with respective ports 50 and 51 which are in communication with the interior of said cylinder and are connected by corresponding conduits 52 and 53 with the hereinbefore mentioned control valve 19.

In the cylinder 45 is mounted for longitudinal reciprocative movement, a piston 54 which is connected to a piston rod 55. The piston rod 55 extends outwardly through a suitable opening 56 provided in the cylinder head'47 and through an enlarged opening 57 provided in the cylinder plate 39 and has the outer end thereof adjustably secured by nuts 58 to a double faced rack member 59, the opening 57 in the plate 39 being of sufficient size to' receive the rack 59 therein. The cylinder plate 39 is also connected with the movable die-supporting plate 35 by means of a toggle link mechanism 60 which is actuated by the rack 59 in the following manner: A pair of links 61 disposed at opposite sides of the rack 59, are each pivotally vconnected at 62 with inwardly projecting lugs 63 secured to or made integral with the cylinder plate 39.

Pivotally connected at 63 to the outer or free end of each of these links 61, is a rock arm 64 which has the other end thereof pivotally connected at 65 to a respective link 66 which in turn are pivotally connected at 67 to respective inwardly extending lugs 68 provided on the inner face of the movable die-supporting plate 35.

The outer adjacent edges of the links 66 and respective arms 64 are provided with abutting shoulders 66' and 64' respectively which, when the pivotal connections .62, 63, 65 and 67 of-the toggle mechanism 60 are in the same straight line, will abut against each other for limiting the inward movement of said links and arms for maintaining said pivotal points in the same straight line.

The rock arms 64 are also pivotally connected intermediate their ends at 69 with a cross head 70 positioned intermediate said arms for maintaining said arms in fixed spaced'relation.

To each of the links 61 is secured a segmental gear member 71 which have the gear teeth thereof in meshing engagement with the teeth of the rack 59 adjacent thereto so that any longitudinal movement of the rack 59 produced by -rthe piston 54 will impart a similar rotating nibvement to the segment 71 and, therefore, to the links 61 for actuating the toggle mechanism 60.

The cross head 70, in this instance, is also provided in its outer face with a recess 70' adapted to receive therein the inner end of the rack 59 when the toggle mechanism 60 is inthe co1- lapsed position.

The face of the movable die-supporting plate 35 adjacent the die section 10 is providedwith a recess 35' adapted to receive therein an ejector plate 73 which is mounted upon guide rods 74 slidably mounted'in the wall of the die-supporttend through suitable apertures provided in the movable die section 10".

These ejector pins areof such a length that when the die sections 10' and 10 are in casting relation with each other and the plate 73 is moved to its extreme outer position, the inner ends of the ejector pins will be in registration with the adjacent inner wall of the die cavity to form a smooth continuous surface.

The supporting rods '74 are of such a length that when the plate '73 is in the extreme outer position and the toggle link mechanism 60 Bin the extended position to maintain the die sections 10 and 10" in casting relation, that said ends will be in spaced relation with the forward end of the cross head '70 and, at'the same time be so related with said cross head, that when the die-supporting plate 35 is moved outwardly to carry the die section 10'. away from the die sec- 'tion 10' by the collapsing of the toggle mechanism 60, that the supporting rods '74 will be engaged by the cross head '70 for moving the plates '73 and ejector pins '75 connected therewith, inwardly through the die section 10" for the purpose of ejecting the casting therefrom. When the die sections 10 and 10" are again brought into casting relation, the ejector pin '75 may again be brought into proper relation with the die cavity by manually moving the ejector plate '73 outwardly or by any other suitable means.

The hereinbefore mentioned control valve 19 may be positioned at any suitable place, adjacent the machine for conveniently controlling the pistons 20 and 54 mounted in the respective cylinders 12 and 45 and for this purpose, is shown mounted. on the bed plate 1 between the supporting brackets 41 and the furnace 2 transversely of the machine which positions the operating handle as 78 near one side of the machine where it may be conveniently manipulated.

The control valve 19, in this instance, consists of a rectangular body member '79 having a centrally located bore 80 extending longitudinally therethrough adapted to form a valve chamber for receiving a valve 81. The ends of the valve chamber 80 may be closed by any suitable means as cover plates 82 and 83 which are secured by screws 84 or their equivalent to the respective vends of the body '79.

' in'this instance, is slidably mounted in a suitable guide 8'7 which is secured to or made integral with a bracket 88 which may be mounted upon the bed plate 1 or, as shown, made integral with the cover plate 83.

The valve body '79 is also provided with an inlet port 89 positioned at one side midway between the ends thereof and a plurality of, in this instance four, outlet ports 90 arranged in two groups of two ports each with a group positioned at each side of the inlet port 89 in uniform spaced relation therefrom.

The outlet port positioned at the extreme left of the inlet port 89 is connected by the conduit 1'7 and port 15 to the rod end of the plungeractuating cylinder 12 while the outlet port positioned adjacent to and at the right of the inlet port 89, is connected by the conduit 18 and port 16 with the head end of said cylinder 12, as hereinbefore described.

The outlet port positioned at the left of the inlet port 89 and adjacent thereto is connected by the conduit 52 and port 50 with the head end of the link-actuating cylinder 45 while the outlet port positioned at the extreme right of the inlet port 89 is connected by the conduit 53 and port 51 with the rod end of said cylinder 45.

The inlet port 89 is connected with the valve chamber 80 by an enlarged annular recess 89' while each of the outlet ports are connected with said chamber by means of enlarged annular recesses 90'. These annular recesses 89" and 90 are spaced a uniform distance apart longitudinally of the chamber 80 so as to form annular walls 80 of substantially equal width between said ports for registering with a pair of enlarged annular flanges 81' and 81" positioned near the outer and inner end respectively of the valve member 81, said flanges being of substantially the same diameter as the interior of the chamber 80 so as to have a close sliding fit therein. These flanges 81 and 81" are also substantially the same width as the walls 80' and spaced apart a distance equal to the distance between the outer .edge of the recess positioned adjacent one end of 1 .of fluid supply such as a pressure pump or storage tank, not shown. by a conduit for supplying fluid, as oil under pressure, through the valve member 19 to the cylinders 12 and 45.

Itwill now. be clearly understood that when the valve 81 is in the extreme left hand or outer position, as illustrated in Figure 4, that the rod end of the plunger cylinder 12 will be in communication with the source of fluid supply and that the head end of said cylinder will be connected with the exhaust conduit 94 by the conduit 18, valve chamber 80, exhaust passage at the right hand end of the valve chamber 80 and the exhaust conduit 94. Likewise, the head end of the link cylinder 45 will be connected with the source of fluid supply by the conduit 52, valve chamber 80 and inlet conduit 95, while the rod end of said cylinder will be connected with the exhaust conduit 94 through the medium of the conduit 53, valve chamber 80 and exhaust passage positioned at.

. disconnected with the exhaust and connected with the source of fluid supply.

The valve 80 may be actuated by any suitable means, as the hereinbefore mentioned lever '78 which in this instance, is pivotally mounted at 9'7 to the bracket 88 in spaced relation with the rack 86. The lower end 98 of the lever '78 extends below and is formed concentric with the pivot 9'7 and provided with gear teeth 98' and adapted to have meshing engagement with the teeth of the rack member 86.

The portion of the lever '78 extending above the pivot 97 is provided with a slot 99 in which is slidably mounted a pawl 100 adapted to engage a circular slot 101 provided in the bracket 88 above the pivot 97 and concentric therewith. This slot 101 is provided with radial grooves 101 in the upper wall thereof for receiving the pawl 100 and maintaining the lever 78 and therefore the valve in a plurality of, in this instance three, predetermined positions.

The pawl 100 is yieldingly maintained in the groove 101' by means of a rod 102 and spring 103, said rod being secured to the pawl 100 at one end and extending upwardly through a suitable opening provided in the upper end of the lever 78 and terminating in an enlarged inwardly extending bore 104 provided in the outer end of said lever. Secured to the upper end of the rod 102 so as to project a short distance above the lever 78 is an annular nut 105, said spring 103 being positioned in the bore 104 between the nut 105 and the inner end of said bore.

The hereinbefore mentioned control valve 33 has one side thereof connected with the conduit 32 which, as before'stated, is connected with the passage 31 provided in the supporting frame 7, and the valve is also connected at its opposite side with a suitable means for producing a vacuum such as a pump, not shown, by means of a conduit 107. This valve 33 may be of any suitable construction and supported in operative relation with the valve rod by the conduits32 and 107.

The valve, in this instance, consists of a body 108 havinga tapered bore 108 therethrough for receiving a similarly tapered rotor 109 which has a port 110 extending transversely therethrough for connecting and dis-connecting the conduits 107 and 32 when said rotor is rotated.

This rotation of the rotor 109 may be accomplished in any suitable manner as by a rock arm 111 secured at one end to the rotor stem 112 while the otherend of the rock arm 111 is forked to receive a pin 112' mounted in an am 113 secured to the valve stem 85 so that as the valve stem 85 is moved for actuating the valve 81, the valve 33 will be simultaneously actuated, thereby connecting and disconnecting the'plunger chamber 25 with the vacuum-producing means.-

It will now be evident by referring to Figures 1 and 2, that the movable die-supporting plate 35 and the cylinder-supporting plate 39 may be adjusted along the tie rods 36 and the supporting rod-40 by the proper manipulation of the nuts :38 for the correct positioning of the die sections 10' and 10" to bring them into casting. relation and permittingthe use of die sections of difierent thicknesses, and for this purpose, the conduits 52 and 53 connecting the link cylinder 45 with the control valve 19, are provided with a suitable number of swivel joints 115 which permit the necessary change in the positioning of the cylinder 45 to accomplish this adjustment of the movable die-supporting plate without the necessityof renewing or changing said conduits.

Operation In operation, the crucible 3 is filled with molten metal such as aluminum, to a level above the inlet of the feeder tube 27 such as indicated by the dotted line X in Figure 2. The valve 81 of the control valve 19 is moved to the position illustrated in Figure 4 at the extreme left hand nect the rod end of the plunger-actuating cylinder '12 with the source of fluid supply which will position the piston 20 at the outer or head 'end of said cylinder and'cause the plunger 24 to be in registration with the outer edge of the inlet passage 29 of the plunger box 25.

The piston 54 will also be in the position shown in Figure 2 due to the head end of the cylinder 45 being connected with the source of fluid supply. This will cause the link mechanism 60 to be in the extended position which will cause the die sections 10 and 10" to be in casting relation with each other with the gate 30 in communication with the plunger chamber 25' of the plunger box 25. The valve 33 will also have been manipulated by the valve stem 85 to connect the passage 31 in the supporting frame '7 with the vacuum-producing means. This positioning of the valve 33 will create a partial vacuum in the die cavity, gate 30, plunger chamber 25 and feeder tube 28 thereby permitting the molten aluminum in the crucible 3 to be forced upwardly by atmospheric pressure through the feeder tube 28 into the plunger chamber 25 until said plunger chamber is completely filled with the molten aluminum at which time the aluminum will enter the restricted passage 24' in .the plunger 24 and become solidified therein thereby cutting oil the plunger chamber 25 from the vacuum and terminating the flow of the metal into said chamber.

As soon as the plunger chamber 25' has been filled with the molten metal, the valve 81 will be moved by the proper manipulation of the lever 78 inwardly to the second position which will cut off the rod end of the cylinder 12 from the source of fluid supply and connect the head end therewith and at the same time, connect the rod end of said cylinder with the exhaust 94 as previously described. This will cause the piston 20 to move inwardly forcing the plunger 24 along the plunger chamber 25' which will force the metal from said chamber into the die cavity un der very high pressure.

As soon as the valve 81 has been moved to the second position, the valve 33 will be closed by the action ofthe valve stem 85-upon the rotor 109 through themedium of the arms 111 and 113 thereby shutting off the vacuum from the plunger chamber 25'. As the plunger 24 moves across the passage 29, said passage will be connected with the atmosphere by means of a small groove 24" formed in the outer end and in the undersurface of the plunger 24, thereby permitting the molten metal contained in the feeder tube 28 to return to the crucible 3 before said metal becomes solidified.

After the die cavity has been filled, it is evident that the excess material will be positioned at the forward end of the plunger chamber 25' in connection with the sprue formed in the gate 30 and that the material solidified in the passage 24' in the upper face of the plunger 24 will also be connected with the excess material.

After the die has been filled, the valve 81 is again moved inwardly'to the third position which will connect the rod end of the cylinder 45 with the source of fluid supply and. cause the piston 54 mounted in said cylinder, to move outwardly.

This outward movement of the piston 54 will supporting plate 35and the die section 10" con- 1,954,775 'nected therewith outwardly away from the fixed die section 10'. This outward movement of the die-supporting plate 35 will carry the casting formed in the die, together with the excess material remaining in .the plunger chamber 25' therewith, and as the movable supporting die plate approaches the limit of its outward movement, the casting will be ejected from the die section 10 by the ejector pins 75 in the manner hereinbefore described.

After the casting has been removed, the valve 81 may again be moved outwardly to the extreme left hand position which will cause the piston 54 to move inwardly and return the die section 10 into casting relation with the die section 10 and then the return of the plunger 24 to the original position, due to the action of the fluid under pressure upon the piston 20, and at the same time, the valve 33 will again be opened to connect the plunger chamber 25- with the vacuum-producing means for again producing the vacuum in said chamber and permittingthe molten metal contained in the crucible3 to be moved by the atmospheric pressure through the feeder tube into the plunger chamber for filling said chamber in the manner hereinbefore described.

This cycle of operation may be continued as long as the molten metal contained in the crucible 3 assumes a level above the inlet to the feed tube 28.

It is apparent that there has beendescribed and shown a very compact, economically con structed device which is positive and automatic in operation, and although we have shownand described the preferred embodiment of this invention, it is not wished to be limited to the exact construction shown, as various changes both in the form and the relation of the parts thereof may readily .be made without departing from the spirit of this invention, asset forth in the appended claims.

We claim:

1. In a die-casting machine in combination with movable die sections and a crucible, of a chamber adapted to contain -.molten metal mounted intermediate the die sections and crucible, metal-conveying -means connecting said chamber with the interior of the crucible and with the die sections, a plunger slidably mounted in said chamber, a conduit adapted to connect said chamber with the vacuum-producing means to cause molten metal to fiow from the crucible into the chamber, said passage being arranged so as to be closed by the molten metal at a predetermined level of said metal for controlling the vacuum in said chamber, fluid-actuated means for moving said plunger to discharge the metal from the chamber into said die sections, separate fluid-actuated means for moving said die sections into and out of casting relation with the chamber, fluid-controlled means for effecting the successive operation of said plunger and die sections, and separate means actuated by the fluid-controlledmeans for automatically cutting off the vacuum during the casting operation.

2. In a die-casting machine in combination with a die and a crucible, of a chamber adapted to contain molten metal mounted over said crucible, metal-conveying means connecting said chamber with the interior of the crucible and with said die, means adapted to connect said chamber with a vacuum-producing means to cause molten metal to flow from the crucible into the chamber, means for ejecting the metal from the chamber into said die, and means actuated by the ejecting means for automatically cutting off the vacuum to said chamber during the casting operation.

3. In a die-casting machine in combination with a die and a crucible, of a chamber adapted to contain molten metal mounted over said crucible, metal-conveying means connecting said chamber with the interior of the crucible and with the die, fluid-conveying means adapted to connect said chamber with a vacuum-producing means for causing molten metal to flow from the crucible into the chamber, ejector means for forcing the molten metal from the chamber into the die, a valve mounted in said fluid-conveying means, and operating means connecting ,said valve with the ejector means for automatically operating the valve to cut off the vacuum in the chamber during the casting operation.

4. In a die-casting machine in combination,

with a die and a crucible, of a chamber adapted to contain molten metal mounted intermediate the die and crucible, metal-conveying means connecting said chamber with the interior of the crucible and with said die, fluid-conveying means adapted to connect said chamber with a vacuum- .producing means to cause molten metal to flow from the crucible into said chamber, means associated with the fluid-conveying means and controlled by the molten metal in the chamber for cutting off the vacuum and limiting the flow of metal into the. chamber to 'a predetermined amount, and mechanical means for ejecting the metal from the chamber into said die.

5. In a die-casting machine in combination with'a die and a crucible, of a plunger box hav ing a casting chamber therein in communication with the die, said box being provided with a passage adapted to be connected with a vacuum-producing means, conveying means connecting said chamber with the interior of the crucible, a plunger slidably mounted in the chamber for ejecting molten metal from the chamber into the die, said plunger being provided with a passage adapted to connect the chamber ahead of the plunger with the first-mentioned passage to cause molten metal to fiow from the crucible into said chamber, said second-mentioned passage being adapted to be closed by the molten metal in the chamber at a predetermined level thereof for controlling the vacuum in said chamber.

6. In a die-casting machine in combination with a die and a crucible, of a chamber adapted to contain molten metal mounted over the crucible with the outlet thereof in communication with the die, metal-conveying means connecting said chamber with the interior of the crucible, fluid-conveying means adapted to connect said chamber with a vacuum-producing means to cause molten metal to flow from the crucible through saidmetal conveying means into the chamber, means for ejecting the metal from the chamber into the die, and vent means controlled by the movement of the ejector means and adapted to connect said metal conveying means with the atmosphere for permitting the molten metal contained in said conveying means to return to the crucible as the metal contained in the chamber is being ejected therefrom.

. NATHAN LESTER.

WILLIAM J. DURING.

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