US2856656A

US2856656A - Die casting machine

Info

Publication number: US2856656A
Authority: US
Publication date: 1958-10-21
Anticipated expiration: 1975-10-21

Description

Oct. 21 1958 4 Sheets-Sheet 1 Filed Aug. 2. 1954 m m m m R m m N A m a w 1 w 6 m bw fi dfw NM, mfi m fi NM, M mm Om 3 MW WW m N ANIIII Oct.2l, 1958 L. RING 2,856,656

I DIE CASTING MACHINE Filed Aug. 2. 1954 4 Sheets-Sheet 2 INVENTOR. Z(/C'/4/V lF/NG BYW L. RING DIE CASTING MACHINE Oct. 21, 1958 Filed Aug. 2. 1954 4 Sheets-Sheet 3 INVENTOR.

Arramwars Oct. 21, 1958 L. RING DIE CASTING MACHINE Filed Aug. 2. 1954 4 Sheets-Sheet 4 INVENTOR. 406/ A/ PIA/6 BY DIE CASTING MACHINE Lucian Ring, Detroit, Mich., assignor to Ring Aluminum Development Company, a corporation of Michigan Application August 2, 1954, Serial No. 447,279 11 Claims. (Cl. 22-68) This invention relates generally to pressure casting equipment and refers more particularly to improvements in equipment of the type disclosed in my copending application-Serial No. 382,079, filed September 24, 1953, now Patent No. 2,837,792, granted June 10, 1958.

In die casting, certain metals such, for example, as aluminum, aluminum alloys and metals having similar characteristics, it has been the practice to ladle the required amount of molten metal by hand into the pressure chamber of a suitable die casting machine in advance of the plunger and thereafter operate the plunger to inject the molten metal into the die cavity. Hand ladling of the molten casting material into the pressure chamber not only consumed considerable time and, hence, reduced the rate of production of a given machine but, in addition, rendered it difficult to produce uniform castings due to casting material supplied to the pressure chamber.

In my above identified copending application, the molten casting material is drawn into the pressure chamber by vacuum produced within the pressure chamber in response to return movement of the plunger and this material is subsequently injected into the die cavity of the machine by the plunger as the latter is moved on its pressure stroke within the pressure chamber. This arrangement eliminates the hand ladling operation heretofore considered necessary and renders the machine completely automati so that the rate of production of the machine is not only substantially increased but, in addition, more uniform castings are obtained.

In die casting apparatus of the type set forth in the preceding paragraph, the quantity of molten material admitted to the pressure chamber um produced in the pressure chamber is metered through a supply passage and does not substantially exceed the amount required to fill the die cavity and associated gate. This is accomplished by providing the supply or metering passage with an effective cross sectional area predetermined with respect to the volume of the cavity and the vacuum produced in the pressure chamber. The predetermined cross sectional area of the supply passage must be maintained over long periods of use regardless of the temperature of the molten casting material and regard less of any characteristic this material may possess which tend to corrode or otherwise deteriorate the walls of the supply passage. For example, aluminum and alloys of aluminum have a chemical as well as a physical action on the walls of the supply passage and continued flow of this material through the supply passage has a tendency to increase the size of the latter to such an extent that the amount of molten casting material admitted to the pressure chamber greatly exceeds the requirements.

With the above in View, it is an object of this invention to provide a die casting machine wherein the predetermined cross sectional area of the supply passage is maintained over long periods of use regardless of the temperature of the molten material and regardless of the variations in temperature of the molten by the action of the vacu- The slide 27 is mounted on chemical or physical action of the material on the walls of the supply passage.

It is another object of this invention to provide a supply unit wherein the supply passage for metering the flow of molten casting material into the pressure chamber is formed in a removable tip composed of a sintered The foregoing as well as other objects will be made more apparent as this description proceeds especially when considered in connection with the accompanying drawings, wherein Figure l is a side elevational view partly in section of die casting apparatus constructed in accordance with this invention;

Figure 2 is a cross sectional view taken on the line 2-2 of Figure 1;

Figure 3 i a cross sectional view taken on the line 3-3 of Figure 1;

Figure 4 is a sectional view line 4-4 of Figure 3; j i

Figure 5 is a cross sectional view taken on the line 5--5 of Figure 4;

Figure 6 is a sectional view taken on the line 66 of Figure 2;

Figure 7 is a cross sectional view taken on the line 7-7 of Figure 6;

Figure 8 is a cross sectional view taken on the line 88 of Figure 6;

Figure 9 is a cross sectional view taken on the line 99 of Figure 1;

Figure 10 is a sectional'view taken on the line 1010 of Figure 5;

Figure 11 is an enlarged sectional view taken on the line 11-11 of Figure 1;

Figure 12 is a flow diagram of a part of the apparatus;

Figure 13 is a sectional view taken on the line 13 13 of Figure 11;

Figure 14 is a semi-diagrammatic elevational view of a part of the apparatus shown in Figure 1;

Figure 15 is a sectional view taken on the line 1515 of Figure 4; and

Figure 16 is an enlarged sectional view of a part of the feeding means for molten casting material.

In Figure l of the drawing, the numeral 20 designates a typical die structure having a stationary part 21 and a movable part 22. The part 21 is suitably fixed to a frame. member 23 and the part 22 is supported at the outer side of the part 21 for movement toward and away from the latter part. The adjacent surfaces of the die parts are fashioned to form a cavity 24 in the closed position of the die and to provide a passage or gate 25 leading into the cavity 24.

The part 22 is secured to housing 26 having the outer taken substantially on the the inner end of an annular end mounted on a slide 27. guide bars 28 having their inner ends secured to the frame member 23. Any suitable means not shown herein may be used for moving the slide 27 in opposite guides 28 to open and close the die 20.

Mounted within the housing 26 is an ejector plate 29 having pins 30 extending inwardly from the plate 29 through bores formed in the die part 22 and registering with the die cavity 24. The plate 29 is actuated to eject the casting from the die cavity by a rack bar 31 and pinion 32. The bar 31 is secured to the plate 29 at the outer side of the latter and meshes with the pinion 32 which is driven by any suitable means not shown herein.

Molten metal is introduced into the die cavity 24 through an injection or pressure cylinder 33 having an outer end projecting through aligned openings in the frame member 23 and fixed die part 21, as shown in Figures 1 and 4 of the drawings. The outer end of the cylinder 33 is open and communicates with the die cavity 24 through the medium of the passage 25. The open outer end of the cylinder 33 may be closed by a cylindrical plug 34 slidably supported within a bore formed in the movable die part 22 and having an annular tapered seat 35 at the inner end engageable with an annular tapered seat 36 surrounding the open end of the cylinder 33. The angle of taper of the seats 35 and 36 is preferably somewhat different in order to assure a fluid tight seal between said seats when in contact.

As shown in Figure 1 of the drawings, the plug 34 is reduced at its outer end and projects axially through the movable die 22 for connection to the inner end of a lubricant supply tube 37. The tube 37 projects outwardly through an opening in the center of the plate 29 and is slidably supported by a bushing 38. The inner end of the tube 37 communicates with fluid passages formed in the plug 34 in a manner to lubricate the walls of the bore formed in the die part 22 and the outer end of the tube is connected in any suitable manner to a source of lubricant supply. In this connection, it is to be noted that the bore in the movable die part 22 within which the plug 34 is slidably supported is vented to the atmosphere by a passage 39 formed in the movable die part 22. The purpose of the passage 39 is to prevent a pressure from building up at the outer side of the plug 34 during outward movement of the plug relative to the movable die part 22. In addition, it is to be noted that the outer end of the reduced portion of the plug provides a shoulder 40 which is engageable by the ejector plate 29 as the latter is moved inwardly to eject a casting from the cavity 24. The arrangement is such that the plug 34 is moved axially inwardly into sealing engagement with the open outer end of the cylinder 33 by the ejector plate 29 when the latter is operated to eject a casting from the die cavity 24. In any case the plug 34 closes the outer end of the cylinder 33 when the die is opened and renders it possible to produce a vacuum within the cylinder 33, as will be presently described.

The inner end of the cylinder 33 is supported in a block 41 which is shown in Figure 3 of the drawings as formed with a vertically elongated opening 42 therethrough for receiving the cylinder 33. The lower end of the opening 42 is shaped to provide an extended hearing contact with the adjacent outer surfaces of the cylinder 33 and the latter surfaces are maintained in contact with the block by a set screw 43 threadably supported in the block at the top of the latter in a position to extend into the upper end of the opening 42 and engage the cylinder 33. As shown in Fig. 11, the bottom of the block 41 is slotted or cut away to provide a clearance opening 44 directly opposite an intake port 45 formed in the cylinder 33 at the bottom of the latter. The arrangement is such that the intake port 45 is accessible for connection to a source of molten metal supply which will be more fully hereinafter described.

Mounted within the cylinder 33 is a plunger 46 having a reduced part at the outer end externally threaded for detachable engagement by a head 47 which, as shown in Fig. 4, is dimensioned to slidably engage the inner surface of the cylinder 33. The inner end of the head 47 is spaced from the shoulder 44 formed on the plunger 56 and a piston 57 slidably supported within the cess 49 of the bearing by the reduced outer end of the latter and rings 45' of sealing material are supported on the reduced outer end of the plunger 46. These rings have a wiping action on the inner surface of the cylinder 33 during movement of the plunger 46 in the cylinder and are clamped in place against the shoulder 44' by the head 47. As shown in Figures 6-8 inclusive of the drawings, the inner end of the plunger 46 is supported by a bearing block 48 having a recess 49 which is open at the top to freely receive the inner end of the plunger 46 and a clamping member 536. The portion of the recess 49 at the outer end of the block 48 is shaped to form a saddle 51 for supporting the inner end of the plunger 46, and the clamping member 5% assumes a position in the recess 49 at the inner end of the plunger 46. An annular enlargement 52 is formed on the inner end of the plunger 46 and abuts a shoulder 53 formed on the bearing block 48 to prevent outward axial displacement of the plunger 46 relative to the bearing block 48. Inward axial displacement of the plunger 46 relative to the bearing block 48 is prevented by the clamping member 50 which is secured in the reblock by a stud 53'. Upward displacement of the inner end of the plunger 46 relative to the bearing block 48 is prevented by a rib 54 formed on the outer face of the clamping member 56 in a position to engage the top of the enlargement 52, as shown in Figures 6 and 8 of the drawings. The above construction is such that the inner end of the plunger 46 is readily removably secured to the bearing block 48.

The bearing block 48 also serves as a coupling for connecting the inner end of the plunger 46 to a hydraulic motor 55. The hydraulic motor 55 comprises a cylinder cylinder 56. As shown in Figure 1 of the drawings, the outer end of the cylinder 56 is secured to a suitable support 58 and the piston 57 is connected to a rod 59 which projects outwardly through the outer end of the cylinder I 56. The outer end of the rod 59 is secured to the bearing block 48 in a manner such that movement of the piston 57 in the cylinder 56 imparts a corresponding movement to the plunger 46.

As shown in Figure 12 of the drawings, the piston 57 is operated by a hydraulic fluid medium contained in a reservoir 69 and circulated by a pump 61. The intake side of the pump 61 is connected to the reservoir 60 by a conduit 62 and the discharge side of the pump is connected to a control valve 63. The valve 63 is, in turn, connected to opposite ends of the cylinder 56 and to the reservoir 60 in a manner such that movement of the valve in opposite directions alternately connects opposite ends of the cylinder 56 to the pump and reservoir. The valve 63 may be and preferably is automatically operated to move the plunger 46 back and forth in the cylinder 33 in accordance with a predetermined timed cycle of operation. The means for automatically operating the valve 63 is not shown herein but may be and preferably is the same as the means disclosed in my copending application Serial No. 382,079.

More particularly, upon completion of a casting in the die 20, the parts of the latter are relatively moved to their open positions and the ejection plate 29 is operated to eject the casting from the die cavity 24. At the same time, the ejection plate 29 engages the plug 34 and moves the same inwardly into sealing relationship with the outer end of the cylinder 33. The valve 63 then operates to connect the outer end of the cylinder 56 to the pressure side of the pump 61 and to connect the inner end of the cylinder 56 to the reservoir 60. Thus the piston 57 is moved in an inward direction in the cylinder 56 to impart a corresponding inward movement to the plunger 46 in the cylinder 33. Since the outer end of the cylinder 33 is closed by the plug 34, inward movement of the plunger 46 produces a vacuum in the cylinder 33 and the resulting suction is communicated to the intake port 45 when the plunger 46 assumes its retracted position inwardly beyond the intake port 45.

As will be presently described, this suction draws a quantity of molten casting material such, for example, as aluminum or alloys of aluminum upwardly through the port 45 into the cylinder 33 at the outer side of the plunger 46. Upon completion of this operation, the valve 63 again operates to reverse the connections aforesaid to the pump 61 and reservoir 60 to move the plunger 46 out- Initial outward movement of the plunger 46 closes the intake port 45 in the cylinder 33 and continued outward movement of the plunger 46 forces the molten material into the die cavity 24 which has previously been closed. In this connection it will be understood that the ejector plate 29 is moved to its inoperative position in timed relation to closing of the die cavity 24, enabling the plug 34 to be moved outwardly relative to the not obstruct the flow of molten casting material from the cylinder 33 into the die cavity 24.

The vacuum produced within the cylinder 33 upon retracting movement of the plunger 46 is sufficient to draw the amount of molten casting material into the cylinder 33 required to properly fill the die cavity 24 and associated The vacuum or the amount of pressure drop produced in the cylinder 33 may be varied by regulating the rate of retraction of the plunger 46 and/ or by providing relief areas in the seating surface of either the plug 34 or adjacent end of the cylinder 33 to enable the escape of a limited amount of air into the cylinder 33 as the plunger 46 is moved inwardly relative to this cylinder.

In order to produce satisfactory castings on a high volume production basis with a minimum loss of shutdown time for servicing, it is essential to not only supply the correct amount of molten casting material to the die cavity 24, but to also maintain this predetermined supply uniform over long periods of operation. in accordance with the present invention the quantity of molten casting material supplied to the cylinder 33 is metered with respect to the pressure drop created in the cylinder 33 upon retracting movement of the plunger 46, and with respect to the capacity of the die cavity 24 and associated passage or passages 25. However, this feature alone does not assure satisfactory operation for long periods without servicing especially in instances where the molten casting material employed has a physical as well as a chemical action on the material through which the metering orifice is formed. Such casting materials attack the Walls of the orifice and increase the size of the orifice to such an extent that far too great a quantity of molten casting material is supplied to the cylinder 33.

The foregoing is a critical problem in the commercial application of die casting apparatus of the type disclosed herein and this problem is solved by the structure of the unit to be presently described for connecting the intake port 45 in the cylinder 33 to a source of supply 65 for the molten casting material. In detail, the source of supply 65 comprises a container 66 supported in any suitable manner directly below the intake port 45 formed in the pressure cylinder 33 and having the top open to the atmosphere. Positioned between the container 66 and the cylinder 33 is a conducting device 67 for molten casting material housed within the container 66. The device 67 has a block 68 elongated in a vertical direction and fashioned with a supply passage 69 extending there through from one end to the other. The bottom portion of the block 68 projects into the container 66 through the open top of the latter and is immersed into the molten casting material. Thus, the atmospheric pressure acting on the top surface of the molten casting material in the container 66 tends to force this material upwardly through the supply passage 69.

The wall of the block 68 forming the top of the passage 69 is tapered outwardly to provide an annular seat 70 for the lower end of a plug 71 which is correspondingly tapered to provide a fluid tight joint with the block 68, and which has a vertically extending metering passage 72 registering with the passage 69. The upper end of the plug 71 projects into a recess 73 formed in the cylinder 33 around the intake port 45, and the passage 72 in the plug also registers with the intake port 45. As shown in Figure 16 the upper end of the plug 71 is fashioned with an annular seat 73 surrounding the corresponding end cally shaped and the seat 73 is rounded in cross section to have a continuous line contact with the seat 74. Thus, a fluid tight joint is provided between the seats with a minimum area of contact of the seating surfaces. This that the plug is not only removably supported on the block 68 but, in addition, is reversible. Hence, should one of the seats 73 become defective, the plug 71 may merely be reversed and, should the plug become otherwise defective, it may be readily replaced. Also, the plug 71 may be quickly interchanged with plugs having metering passages 72 of diiferent cross sectional areas.

It follows from the above that the amount of molten material admitted to the cylinder 33 through the intake as uniform operation of the die casting equipment for long periods of use without servicing, the plug 71 is formed of a sintered compound such as tungsten carbide,

cross sectional area of the metering passage 72 uniform over long periods of use.

In operation, the molten material drawn into the cylinder 33 through the intake port 45 impinges on the wall directly opposite the port 45 and eventually causes severe corrosion of the metal. In order to overcome this objection, a plug 75 is removably secured to the wall of the cylinder 33 directly opposite the intake port 45 by the set screw 43. The plug 75 may be formed of the same material as the plug 71 and, in any case, is readily replaceable.

In the present instance, the block 68 together with the plug 71 is supported for movement toward and away respectively extending upwardly along opposite sides of the cylinder 33 and, respectively, threadably engageable with the lower ends of rods 78. The rods 78 slidably engage opposite sides of the block 41 and the upper ends '7 of the rods are reduced to provide annular shoulders 79. The reduced upper ends of the rods extend through openings formed in a cross head 80 at opposite ends of the latter, and bushings 81 are respectively supported by the cross head 83 within the openings to slidably engage the rods 78.

The cross head 80 is normally urged in a downward direction toward stops 82, seated on the shoulders 79, by coil springs 83 respectively surrounding the upper ends of the rods 78. The lower ends of the coil springs 83 engage the cross head 80 and the upper ends of the springs 83 engage adjusting nuts 84 secured to the upper end of the rods 78. The central portion of the cross head 80 between the two rods 78 is connected to the lower end of a piston rod 85 having the upper end connected to a piston 86 which is slidably supported within a vertically extending hydraulic cylinder 87. Any suitable valve controlled means (not shown) may be provided for alternately connecting opposite ends of the cylinder 87 to a reservoir and a source of hydraulic fluid under pressure. The arrangement is such that movement of the cross head 80 in a downward direction by the piston 86, lowers the yoke 76 sufliciently to disengage the plug '71 from the cylinder 33. On the other hand, movement of the cross head 80 upwardly by the piston 86, raises the yoke 76 and engages the plug 71 with the cylinder 33. In this connection attention is called to the fact that upward movement of the plug 71 into engagement with the cylinder 33 is effected through the coil springs 83 with the result that said springs absorb the shock of engagement of the plug 71 with the cylinder 33 and prevent damage to the seating surfaces on the plug and cylinder.

In order to avoid overheating the cylinder 33 and plunger 46 by the molten metal during the ejecting operation, provision is made herein for cooling the aforesaid parts. As shown in Figures 4, 5, 9 and of the drawings, the outer end of the cylinder 33 is fashioned to provide a series of passages 88. The passages 38 extend in the general direction of length of the cylinder 33, but are inclined with respect to the cylinder axis to such an extent that the ends of adjacent passages communicate with one another and provide in effect a single circuitous passage. Water or some other cooling medium is circulated through the passages and for accomplishing this result intake and

outlet conduits

89 and 90 are respectively connected to opposite ends of the circuitous passage formed by the passages 83. In addition to the above cooling arrangement, the cylinder 33 has diametrically opposed bores 91 extending axially outwardly from the inner end of the cylinder and connected to outlet conduits 92, as shown in Figure 4 of the drawings. Extending axially into each of the bores 91 from the inner end of the cylinder 33 is a tube 93 having a diameter substantially less than the diameter of the bores 91 to provide a jacket for a cooling medium within the bores 91. The inner ends of the tubes 93 are respectively connected to intake conduits 94 which in turn communicate with a source of cooling medium supply, not shown herein. Thus, it will be seen that the cylinder 33 is effectively cooled and is maintained at a more or less uniform temperature throughout the operation of the apparatus.

As shown in Figures 2, 4, 6 and of the drawings the plunger 46 has a bore 95 which extends axially of the plunger from the inner end of the latter and is divided into two communicating passages 96 by a partition 97. Referring now to Figure 2 of the drawings, it will be noted that one passage 96 communicates with an intake couduit 98 for cooling medium under pressure, and the other passage 96 communicates with an outlet conduit 99 for the cooling medium. Consequently, the cooling medium is circulated axially of the plunger 46 and the latter is also maintained at a substantially uniform temperature during the casting operation.

Provision is also made herein for lubricating the inner surface of the cylinder 33 during operation of the plunger 46. For accomplishing this result, the plunger 46 is formed with an axially extending lubricant passage 100. The inner end of the passage 1% is connected to a source of lubricant supply by a conduit 102 and the outer end of the passage communicates with the interior of the cylinder 33 at the inner side of the head 47 on the plunger 41% through ports N3.

In the present instance, the lubricant supply conduit 132 is connected to a lubricant supply cylinder 104 through a control valve 105 and a regulating valve 106 by a conduit 107, as shown in Figure 14 of the drawings. The cylinder 164 contains lubricant under pressure so that opening of the valve 105 causes lubricant to flow into the cylinder 33 through the passage in the plunger 46 at a rate depending upon the adjustment of the valve W6. The valve Hi5 is operated to supply lubricant to the cylinder 33 each time the die 20 is closed and is actuated by a roller 1% mounted on the slide 27. If desired, the lubricant supply tube 37 for the closure plug 34 may also be connected to the conduit 107 so that a supply of lubricant is introduced into the bore in the die part 22 each time the die is closed.

What I claim as my invention is:

l. in a pressure casting apparatus, a mold cavity, a pressure cylinder having a discharge opening for molten casting material communicating with the cavity and having an inta 1e opening for molten casting material spaced inwardly from said discharge opening axially of said cylinder, a plunger movable in said pressure cylinder in an outward direction outwardly beyond said intake opening to inject molten casting material into said cavity and movable in an inward direction to a retracted position inwardly beyond the intake opening, means for closing said discharge opening upon initial inward movement of said plunger toward its retracted position to provide a vacuum in said pressure cylinder produced solely by the inward movement of said plunger and suflicient to draw molten casting material into said cylinder through said intake opening when the latter is uncovered by movement of said plunger to its retracted position, means for admitting molten casting material to said pressure cylinder including a part having a passage communicating with said intake opening and of a cross-sectional area predetermined to admit a metered amount of molten casting material to said pressure cylinder in response to the vacuum produced in said cylinder by said plunger, said part being formed of a material characterized in that it withstands the temperature of the molten casting material without deterioration and is not affected by the physical and chemical action of the molten material flowing through the passage in said part.

2. The structure defined in claim 1 wherein said part is formed of a material selected from the group consisting of tungsten carbide, titanium carbide and zirconium boride and a binder selected from the group consisting of cobalt and platinum.

3. In a pressure casting apparatus, a mold cavity, a pressure cylinder having a discharge opening for molten casting material communicating with the cavity and having an intake opening for molten casting material spaced inwardly from said discharge opening axially of said cylinder, a plunger movable in said pressure cylinder in an outward direction outwardly beyond said intake opening to inject molten casting material into said cavity and movable in an inward direction to a retracted position inwardly beyond the intake opening, means for closing said discharge opening upon initial inward movement of said plunger toward its retracted position to provide a vacuum in said pressure cylinder produced solely by the inward movement of said plunger and sufficient to draw molten casting material into said cylinder through said intake opening when the latter is uncovered by movement of said plunger to its retracted position, a container for a supply of molten casting material supported below said pressure cylinder, a member projecting downwardly into said container below the level of the molten casting material in said container and having a vertically extending passage communicating at the lower end with level of the molten casting material and communicating at the upper end with said ing of tungsten carbide, titanium boride and a binder selected cobalt and platinum.

4. The structure defined in claim 3 comprising an ancarbide and zirconium from the group consisting of an intake opening for molten material, ducing molten material through the intake opening sage for molten material means for introinto the pressure chamber including a part having a pasof a cross-sectional area preship with respect to 7. The structure the pressure chamber. defined in claim 6 wherein the part is reversible end for end and 1s removably mounted on the support in either position thereof.

8. In pressure casting apparatus, a mold cavity, a prescross-sectional area predetermined to meter the flow of casting material admitted to said pressure chamber, said part being formed of a material characterized in that it withstands the temperature of the molten casting material and is not affected by physical and chemical action of the casting material whereby the predetermined crosssectional area of said passage is maintained for long periods of use, and means for expelling the casting material admitted to said chamber from said discharge opening, said chamber having an annular seating surface surrounding said intake opening at the outer side of the latter, and said part having an annular seating surface engageable 10 with the seating surface on said chamber, said part be ing formed of a sintered carbide material, and said seating surfaces having cross-sectional contours predetermined to provide a continuous line contact therebetween and thereby reduce heat transfer between said part and chamber to a minimum.

9. In pressure casting apparatus, a .mold cavity, a pressure chamber having a discharge opening communicating with said mold cavity and having an intake opening, means for introducing molten casting material into said pressure chamber through said intake opening including a part having a passage for molten casting material of a cross-sectional area predetermined to meter the flow of casting material admitted to said pressure chamber, said part being formed of a material characterized in that it withstands the temperature of the molten casting material and is not affected by physical and chemical action of the casting material whereby the predetermined cross-sectional area of said passage is maintained for long periods of use, and means for expelling the casting material admitted to said chamber from said discharge opening, said chamber having an annular seating surface surrounding said intake opening at the outer side of the latter, and said part having an annular seating surface engageable with the seating surface on said chamber, said seating surfaces having cross-sectional contours predetermined to provide a continuous line contact therebetween and thereby reduce heat transfer between said part and said chamber to a minimum.

10. In pressure casting apparatus, a mold cavity, means for supplying molten casting material to said cavity including a pressure chamber having a discharge opening, said chamber also having an intake opening, means for introducing molten casting material into said pressure chamber through said intake opening including a part having a passage for molten casting material of a crosssectional area predetermined to meter the flow of casting material admitted to said pressure chamber, means for expelling the casting material admitted to said chamber from said discharge opening, said chamber having an annular seating surface surrounding said intake opening at the outer side of the latter, and said part having an annular seating surface engageable with the seating surface on said chamber, said seating surfaces having cross-sectional contours predetermined to provide a continuous line contact therebetween and thereby reduce heat transfer between said part and said chamber to a minimum.

11. In a pressure casting apparatus, a mold cavity, means for delivering molten casting material to said mold cavity incuding a pressure cylinder having a discharge opening, a plunger supported in said cylinder for axial sliding movement in one direction toward said discharge opening to expel casting material in said cylinder from said discharge opening and in the opposite direction away from said discharge opening to a retracted position, said cylinder having an intake port between said discharge opening and said plunger in the retracted position of the latter, means for admitting molten casting material to said cylinder including a part having a supply passage communicating with said intake port and with a supply of molten casting material, and means for closing said discharge opening during movement of said plunger in said opposite direction to its retracted position to provide a vacuum in said cylinder at the side of said plunger toward said discharge opening produced solely by the movement of said plunger in said opposite direction and suflicient to draw molten casting material through said supply passage into said cylinder through said intake port, said passage being of a cross-sectional area predetermined to admit a metered amount of molten casting material to said cylinder in response therein by said plunger, and said part being formed of a material characterized in that it withstands the temperature of the molten casting '11 material without deterioration and is not a'fiected by the physical and chemical action of the molten material flowing through the passage in said part.

References Cited in the file of this patent 5 UNITED STATES PATENTS 1,589,857 Katcher et a1. June 22, 1926 1,781,168 Dollin et a1 Nov. 11, 1930 1,954,775 During et al Apr. 10, 1934 10 1,960,992 During et a1 May 29, 1934 1,961,942 Pack June 5, 1934 12 Lester Mar. 29, 1938 Lester et a1. Mar. 29, 1938 Flammang et a1. May 31, 1938 Morin Jan. 31, 1939 Daesen Mar. 26, 1940 Stahl May 27, 1941 Waldie Nov. 28, 1944 Lester Dec. 3, 1946 Kux Jan. 8, 1952 Zvanut Dec. 21, 1954 Beckes May 17, 1955