US3006043A - Die casting machine and casting process - Google Patents

Description

Oct. 31, 1961 w. M. GOLDHAMER 3,006,043

on: CASTING MACHINE AND CASTING PROCESS Filed April 9, 1959 5 Sheets-Sheet 1 RAGE RESERVOIR INVENTOR PUMP BY 25mm A" on frs WALTER M. GOLDHAMER Oct. 31, 1961 w. M. GOLDHAMER DIE CASTING MACHINE AND CASTING PROCESS 5 Sheets-Sheet 2 Filed April 9, 1959 nnl l Nu I I I II I HHHHHHHH u NHI llllllllllHU INVENTOR WALTER M. GOLDHAMER r ATTORNEYS Oct. 31, 1961 w. M. GOLDHAMER DIE CASTING MACHINE AND CASTING PROCESS 5 Sheets-Sheet 3 Filed April 9, 1959 INVENTOR WALTER M. GOLDHAMER SM nal T ATTORN 1961 w. M. GOLDHAMER 3,006,043

DIE CASTING MACHINE AND CASTING PROCESS Filed April 9, 1959 5 Sheets-Sheet 4 FlG.-7

7 3 FIG. 8

INVENTOR WALTER M. GOLDHAMER Y 7 w. any; 2 16a ATTORNEYS Oct. 31, 1961 w. M. GOLDHAMER DIE CASTING MACHINE AND CASTING PROCESS 5 Sheets$heet 5 Filed April 9, 1959 INVENTOR WALTER M. GOLDHAMER Pumd4 luuwb, 111

ATTORNEY Baum M 7' 3,006,043 DIE CASTING MA CHHNE AND QASTKNG PRUQEEES Walter M. G-oidhamer, hairer Heights, Shin, assignor to gig Casting Research Foundation, Inc., New York,

Filed Apr. 9, 1959, Ser. No. 8953MB 19 Claims. (Cl. 22-4?) This invention relates to die casting operations and apparatus therefor, and has for its object the provision of an improved die casting machine of the type in which the die cavity is either vented to the atmosphere or operated under reduced pressure prior to and during the injection of molten metal. The invention provides means for removing the gas from the die cavity or mold, including the small amount of residual gas which is concentrated or compressed by the advancing metal forced into the die cavity.

The invention provides an improved process for forming die castings in gas impervious molds which are provided with a vent or vacuum duct for gas, and means for forcing molten metal into the die cavity, which comprises removing the gas from the die cavity through the vent or duct in advance of the metal entering the die cavity, cooling the vent or duct to a temperature below the die cavity and, after filling the die cavity, flowing metal into and freezing it in the vent r duct, thereby efiectively removing the gas from the die cavity.

In die casting, the presence of entrapped gas such as air in the die cavity restrains the flow of the metal into the die cavity causing defects in the contour of the casting, blow holes or porosity. When the injection pressure exceeds, for example, one thousand pounds per square inch, the entrapped gas is compressed and dispersed into the casting. Many proposals have been made and devices have been used to remove the gas from the die cavity by venting to the atmosphere or by the application of vacuum but these have not been entirely satisfactory because of the inability heretofore to remove the residual gas from the die cavity in a practical and economical manner.

The invention provides a passageway in the die casting apparatus connecting the die cavity with a vent to the atmosphere or to a vacuum system for evacuating the die cavity while the metal is entering the die cavity and, after filling it, entering the passageway, and means for freezing the metal in the passageway after all the gas has been removed from the die cavity, thereby entirely filling the die cavity without objectionable flow of metal through the passageway. The passageway connecting the die cavity to the vent or vacuum system is provided with cooling means to solidify the metal therein and serve as a chill plug to prevent the flow of metal from the die cavity after removal of all the gas.

The die casting apparatus comprises complementary die members which, during casting, are connected together to form, as near as is practically possible, a gastight cavity for the die casting, and, after casting, separated to remove the casting, at least one of the members being movable into engagement with and away from the other die member, means for injecting molten metal into the die cavity, a metal-cooling member attached to each die member, a continuous passageway formed between the die members and the metal cooling members which connects the die cavity to a vent or a vacuum source. The cooling members are preferably thermally insulated from the die members to suppress the flow of heat into the cooling members. The passageway consists of two parts, one part between the die members which is at a relatively high temperature and is larger than the other part of the passageway which is between the cooling Patented Get. 31, 1961 members, thereby providing a single passageway operated at two different rates of metal flow and two different temperatures. This assures that the metal will flow readily and freely into the die cavity and fill it completely and accurately before the casting solidifies, yet permitting the gas to be vented and the metal to solidify in the part of the passageway within the cooling members and prevent its escape or passage into the vacuum system. By carrying the first portion of the incoming casting metal through and out of the die cavity at a rapid rate a more homogeneous and uniform temperature of the metal of the casting is obtained.

In an effective embodiment of apparatus the die members, preferably of conventional construction, are rigidly and securely connected to and thermally insulated from the cooling members which include chill blocks in heat exchange contact with a coolant medium and between which the passageway is formed for the rapid solidification of the metal. The cooling members are preferably each connected to a die member and one is movable with the movable die member. The passageway portion between the chill blocks is preferably of serpentine or undulating form to provide a large cooling area in a small space, and is proportioned in cross-sectional area to efiect a rapid removal of gas without an excessive loss of metal. The frozen metal in the passageway seals oif the vent or vacuum line, thereby eliminating mechanically operated valves, plungers and like means for this purpose. The part of the passageway between the chill blocks may vary from 0.020 to 0.050 inch in thickness, and the part between the die members is thicker up to, say, about A; inch in thickness. The dimensioning of the passageway is important to effect a rapid removal of the gas and also a rapid solidifying of the metal in the passageway.

The apparatus of the invention makes it possible to remove in one piece the casting and the connected metal which solidified in the passageway, thereby clearing the passageway for the next cycle at the time of removing the casting.

In another aspect of the invention a second passageway as aforementioned is provided for connection to a pressure measuring or recording device to permit continuous measurement of the die cavity pressure throughout the casting cycle. This passageway is preferably connected to the opposite side of the die cavity from the aforementioned passageway which vents the cavity. This arrangement enables one to register or to record simultaneously both the die cavity vacuum level and the pressure, which may also be recorded, in the cylinder which drives the metal injection piston. This eliminates the possibility of the instruments merely measuring the vacuum level in the vacuum system without regard to the restrictions imposed by the passages into the die cavity.

One of the diflicult problems in vacuum die casting is the rapid evacuation of the die cavity and the rapid injection of the metal. Due to unavoidable re-entrant air from leaks around the die members, pins, and the like, as well as the residual gas which becomes appreciable as the metal compresses it, it is important not only to remove this gas but also to record the amount of its pressure.

These and other novel features of the invention will be better understood after considering the following discussion taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side elevational view of a conventional die casting machine in horizontal arrangement embodying the invention;

FIG. 2 is a plan view of the cooling members in connection with die members of the machine of FIG. 1, in closed position;

FIG. 3 is a side elevational view of FIG. 2;

3 7 FIG. 4 is a sectional enlargement of the lower part of FIG. 2;

FIG. 5 is an enlarged sectional view at 5-5 of FIG. 2;

FIG. 6 is a perspective view of the two cooling members of FIGS. 1 to 5;

FIG. 7 is a sectional side view of a portion of the apparatus of FIG. 1 for injecting the molten metal into the die cavity, shown at the beginning of the injection stroke;

FIG. 8 is a view similar to FIG. 7 at the end of the injection stroke;

FIG. 9 is a view similar to FIG. 7 when one die member has been opened for removal of the casting;

FIGS. 10 and 11 are cross sections at 10l0 of FIG.

'7 showing the two positions of the injection piston; and

FIG. 12 is a vertical front view taken facing one of the die members of a modification.

The apparatus illustrated in the drawings and partic ularly as shown in FIG. 1 comprises a die casting machine having a base 1, upright frame members 2 and 3,

tie bars 4 and 5 interconnecting the frame members, a

.die member 6 securely connected to member 3 which has amating complementary die member 7. The bars 4 and 5 are cross-connected by a carriage 8 which is slidable thereon and to which the die member 7 is connected by bracket 12. Carriage 8 is connected by linkage 13 to rod 14 which is operated by a piston in the cylinder 15 to open and close the die member 7.

The die members 6 and 7 are machined to effect tight engagement and have a die cavity 16 therebetween which connects by an upright inlet 17 leading to the cylinder 18 for the injection of molten metal. For convenience of illustration only one die cavity is shown, but it is to be understood that two or'more interconnected cavities may be used in the die members. The cylinder 13 is connected to a pipe 26 which is immersed in the molten metal, for example, aluminum alloys in reservoir 21.

'The assembly of apparatus 22 for injecting the molten metal into the die cavity will be described hereinafter.

The die members 6 and 7 each carry a securely attached cooling member 24 and 25 respectively. Between the die members and chill blocks a continuous vent or evacuation passageway is provided consisting of part 26 between the die members which is relatively thick varying from A to V inch, and part 27 between the cooling members which is relatively thin varying'from 0.020 to 0.050 inch in thickness based upon the cavity volume to be evacuated. The pipe 28 as shown connects the passageway through restricting orifice 30, solenoid valve 31 to the vacuum reservoir 32. 7 When the apparatus is not used for vacuum casting, the pipe 28 is eliminated and the passage 27 vents directly to the atmosphere. The valve 31 is connected by line 33 to an electric switch 34 on the die members 6 and 7 so that the valve 31 is closed when die member'7 is open and is opened to apply vacuum to passageway 27 when the die member 7 is closed. The

orifice is a limiting means to restrict the vacuum at the initial stage. (The valve 31, line 33 and switch 34 may be omitted if desired.) Solenoid valve 35 by-passes valve 31 by pipe 36 and is connected by electric line 37 to the electrically-operated timer control T. The operation of the valves and switches will be described hereinafter. Cooling members 24 and 25 are connected by bolts B to the die members 6 and 7 and are accordingly in rigid secured attachment thereto so that the cooling member 24 remains in stationary fixed position with die member 6 and cooling member 25 is moved to the open and closed positions with die member 7. With particular reference to FIG. 5 it will be noted that the cooling members engage the die members on narrow projections or lands 40 which provide air spaces 41 between the members to serve as thermal insulation and suppress the flow of heat from the die members into the cooling members. The cooling members are each formed of two main parts, nest blocks 42 and 43 formed of a metal such as stainless steel or refractory sintered metal compour ds or other low heat conducting material. In the mating face of block 43 a U-shaped groove 44- is provided for the insertion therein of a gas-sealing gasket 45, such as neoprene, silicone, or Teflon. Each of the nest blocks has a hollow center within which is inserted chill blocks 46 and 47. These chill blocks have a series of channels C on their back surfaces for the circulation therein of coolant fluid passed into the channels through pipes P and discharged from the channels through pipes P. The chill plugs are preferably formed of metal of high heat conductivity such as molybdenum or copper. The chill plugs have corrugated surfaces 48 and 49 which when the chill blocks are in assembled position as shown in FIG. 5 form the tortuous passageway 27a as a part of passageway 27. This undulating passageway extends from the recess in the lower end of a chill block 46 to a chamber 5%? formed in the nest block 25 as shown in FIG. 5. The nest block 42 has a projecting baffle 52 extend- .ing into the space 56 and also a space 53 contiguous with .der to facilitate the removal of the metal that solidifies in the passageway 27 the edges 55 of the corrugations are beveled. As shown in FIGS. 4 and 6, an ejector pin 56 having a projecting head 57 may be inserted in an opening through the nest block and the chill block and has an exterior extension which strikes the frame of the machine when the mold is opened. When the die member 7 and its cooling member 25 are opened the injector head 57 strikes against the metal in the passageway 27 and effects its removal.

If it is desired to measure or record the pressure in the die cavity, additional chill blocks 38' and 39 are connected to the die members 6 and 7, respectively, to provide a passageway 39' connected to the die cavity 16 as is the passage 26 and 27. This passageway is connected to a pressure measuring device 29 which may be a gage or a recording pressure measuring device to register or record the pressure in the die cavity during casting.

This passageway is connected to the die cavity at a place remote from the passageway 26 and permits measuring the actual pressure in the die cavity 16. An alternative arrangement is shown in FIG. 12.

7 The apparatus 22 shown in detail in FIGS. 7-11 is for the controlled injection of measured quantities of molten metal'into the die cavity 16. This apparatus comprises a cylinder 18 secured to the die member 6 which opens into the duct 17 leading directly into the die cavity 16.

extends forward only to the point 62, the functions of which will be described hereinafter. The rod 59 which drives the piston 58 has a head 64 in secured but rotatable connection with the sleeve 65. This sleeve also efiects a threaded connection with the piston rod 66 of the piston operated in the cylinder 67. A locking nut 68 secures the sleeve to both head 64' and rod 66. The cylinder 67 is mounted on a frame 69 and is rigidly attached to the upright frame 3 by two tie rods 72 and 73. The rod 66 is sealed where it passes through the frame 69 with a stufiing gland 74. The piston operable in cylinder 67 is not shown but is understood to be an hydraulically operated piston for driving rods 66, 59 and the piston 58 in response to the cyclic control means'for the machine.

The head 64 has a transverse slot 63 in which the lever arm 75 is inserted. This lever arm has a slot 76 in which ton 58. As best shown in FIG. 10, a bracket 78 is secured to the rod 72. This bracket supports a cylinder 80 having therein an hydraulically operated piston (not shown) which moves the rod 81 and its attached pin 77 backward and forward to turn the lever 75. It will be noted with reference to FIGS. 7 and 8 that the bracket 78 is stationary and remains in secured attachment to the rod 72. The lever 75 engages the pin 77 only when the piston 58 is at the rearward end of its stroke as shown in FIG. 7. The piston in cylinder 80 is operated hydraulically by fluid admitted thereto by the solenoid valve 82. This valve is actuated by the timer T of the casting machine through an electrical circuit connected with line 83. The piston of cylinder 80 is advanced at the end of each machine cycle to turn piston 58 to the position shown in FIGS. 7 and 10, and is retracted at the end of the low level evacuation of the die cavity to turn the piston 58 to the position shown in FIGS. 8 and 11.

The piston in cylinder 15 and the piston in cylinder 67 are operated hydraulically by valve means controlled from the timer T of the casting machine.

The casting apparatus of the invention is operated as follows: When the central timer T is set for operation, the piston in cylinder 15 forces the carriage 8 and the die member 7 with its attached cooling member 25 to the closed position shown in FIGS. 1, 5, 7 and 8. At this time the switch 34 is closed and the valve 31 is open causing a limited vacuum, due to the orifice 30, to be created in the passageways 26 and 27, die cavity 16, duct 17 and cylinder 18. At this time, the lever 75 has turned the piston 58 to the position shown in FIGS. 7 and and a charge of molten metal is sucked upwardly through pipe 20 from the reservoir 21 into the cylinder 18. A short interval thereafter based on the volume of the metal required, the timer T operates sequentially the piston in cylinder 80, the solenoid valve 35 and the piston in cylinder 67. The piston in cylinder $0 turns the lever 75 from the position shown in FIG. 10 to the position shown in FIG. 11 thereby completely disconnecting the forward portion of cylinder 18 from pipe 20. This movement sets the groove 61 over the passage in pipe 20, connecting it to the atmosphere causing the molten metal in contact with piston 58 to return immediately to the vessel 21, thereby preventing this metal from freezing in contact with the piston. At the conclusion of the setting of piston 58, the solenoid valve 35 is opened to apply full vacuum and then the piston in cylinder 67 forces the rods 66 and 59 and piston 58 forward on the injection stroke and the metal in cylinder 18 is forced through the passage 17 and upwardly into the die cavity 16. During this motion and while the full vacuum is applied the metal is entering and filling die cavity 16 and ultimately passes upwardly and with considerable rapidity through the relatively large passageway part 26 and then into the relatively narrow passageway part 27' which is within the cooling members 24 and 25. As a result of the conjoint action of the advancing metal and the vacuum all of the gases contained in the die cavity are removed. A low vacuum as generally used in this are will remove most of the gas from the die cavity. However, when a small amount of residual gas, mostly infiltrated air, is concentrated by the advancing metal, it becomes a contaminant for the metal and results in casting defects and rejects. My improved apparatus removes this residual gas by forcing it into the vacuum system and then freezing the metal in the vent to serve as a plug.

Any small particles of solid metal that may have been retained in the passageways 26 and 27 are blown against the bafile 52 and are trapped by the fibrous metal 54 and thereby prevented from entering the vacuum system. As a result of the low temperature of the chill blocks 46 and 47 the metal in the passageway part 27 is completely solidified before it reaches the chamber 50.

At the completion of this operation the casting machine timer T closes valve 35, reverses the piston in cylinder 15 to move the carriage 8 and the attached die member 7 and cooling member 25 towards the left as viewed in FIG. 1 to open the mold and permit removal of the die casting. Coincident with this movement the ejector part 55 strikes a lug (not shown) on the machine frame and the extreme end 57 thereof which enters the passageway 27 engages an edge portion of the metal web therein and kicks it loose. As a consequence the entire mass of solidified metal and the metal web of the passageway is removed in a single piece.

FIG. 12 illustrates a modification of the apparatus of FIG. 1 and is a side view at the inner face of the die member 7 showing the mounting of the cooling member 25 and a second cooling member 25. This cooling member has a complementary cooling member (not shown) similar to member 24 on die member 6, which forms the passageway 2'7 to which the gage or recording device 29 is attached. It will be noted that the passage 26' enters the cavity 16 at a position opposite the outlet passage 26. This permits the pressure in the die cavity to be measured independently of the pressure in the vacuum system and especially in passageway 26.

My copending application Serial No. 818,079, filed June 4, 1959, describes and claims more fully the improved piston for injecting the molten metal, and also a vertical ram piston as used in zinc die casting. This invention is also applicable to such zinc die casting apparatus in which the piston or ram operates in a pot of molten metal.

This application is a continuation-in-part of my copending application Serial No. 675,206, filed June 30, 1957, now abandonded.

I claim:

1. In a die casting machine including complementary die members which can be connected together to form a die cavity and separated to remove the casting, at least one of the die members being movable into engagement with and away from the other die member, means for injecting molten metal under pressure into the die cavity, a separate metal cooling member secured to each die member, thermal insulating means disposed between the die members and the metal cooling members for suppressing the flow of heat from the die members into the metal cooling members, at least one of said metal cooling members being movable into engagement with and away from the other metal cooling member during movement of the die member to which it is secured, means defining a passageway between the engaged metal cooling members connected to a vaccum duct and to the die cavity, and means for cooling the metal cooling members to solidify metal in said passageway before the metal solidifies in the die cavity.

2. A die casting machine as defined in claim 1 which comprises a die member and a metal cooling member connected together and movable as a unit to open and close both the die cavity and the passageway simultaneously whereby the casting and the attached metal from the passageway may be removed as a unit.

3. A die casting machine as defined in claim 1 which comprises metal cooling members each having a chill block which engages the other chill block and between which the passageway is formed, said chill blocks being formed of a metal of high heat conductivity in comparison with the metal of the mold and having means for the circulation thereon of a coolant liquid.

4. A die casting machine as defined in claim 1 in which the passageway between the chill blocks varies from 0.020 to 0.050 inch and is undulating to provide a long travel for the metal in a short space.

5. A die casting machine as defined in claim 1 which comprises air spaces between the die members and the metal cooling members as thermal insulation to suppress the flow of heat from the die members into the cooling members. i

6. In a die casting machine including complementary :die members which can be connected together to'form a die cavity and separated to remove the casting, at least one of the die members being movable into engagement with and away from the other die member, means for inecting molten metal under pressure into the die cavity, a separate metal cooling member secured to each die member, thermal insulating means disposed between the die members and the metal cooling members for suppressing the flow of heat from the die members into the metal cooling members, at least one of said metal cooling members being movable into engagement with and away from the other metal cooling member during movement of the die member to which it is secured, means defining a passageway between the engaged metal cooling members connected to a vacuum duct and to the die cavity, a passageway between the die members connected to the passageway between the cooling members, the passageway part between the cooling members being at least 0.020 inch thick and tortuous for the rapid solidification of metal therein, the passageway part between the die members being much thicker for the rapid flow of metal therein from the die cavity, and means for cooling the metal cooling members.

7. A die casting machine as defined in claim 6 which comprises electrical switch means operated with the movable die member and an electrically operated valve in the vacuum duct for evacuating the passageway and die cavity when the die member is in closed position.

8. A die casting machine as defined in claim 7 which comprises a second electrically operated valve in the vacuum duct for efiecting an initial vacuum in the die cavity which is followed by a lower vacuum when the first-mentioned electrically operated valve is opened.

9. In a die casting machine of the type having a die cavity and means for injecting molten metal therein under pressure, the improvement which comprises one die member having a part of the die cavity therein which is immovably secured to the machine, a cooling member fixed to the die member, thermal insulating means disposed between the die members and the metal cooling members for suppressing the flow of heat from the die member into the cooling member, a complementary die member also having a part of the die cavity therein, another cooling member fixed to the complementary die member, thermal insulating means disposed between the die members and the metal cooling members for suppressing the flow of heat from the complementary die member into the cooling member attached thereto, means for circulating a cooling fluid in the cooling members, means for moving the complementary die member and its cooling member fixed thereto into close fitting contact with the die member and its cooling member respectively, means between the die members and the cooling members defining a passageway which passageway is connected at one part to a source of vacuum and at another part to the die cavity, said passageway between the cooling members is tortuous and the part formed between the die members is not tortuous whereby the metal, after filling the die cavity, enters the passageway forming residual gas not removed by the vacuum out ahead of it and then enters the tortuous part and solidifies in the passageway part between the cooling members, and means for moving the complementary die member and its cooling member away from the fixed die member and its cooling member for the removal of the die casting and the metal solidified in the passageway as a unitary structure.

10. In a die casting machine including complementary die members cooperating to provide a die cavity, one of said members being movable to open and close said cavity, a metal inlet communicating with said cavity in one of said members, a bi-sectional separable heat exchanger on said members having an air outlet passageway not less than 0.020 inch in thickness therein communicating with said cavity, a vacuum line connected to said passageway, means for passing a cooling fluid in contact with the heat exchangers, a molten metal reservoir adjacent one of said die members, a cylinder superjaceut thereto communicating with said cavity, a piston in said cylinder, a conduit in said reservoir connected to said cylinder, a valve in said vacuum line, a by-pass line having a restricted passageway therein which is looped around said valve, a second valve in said by-pass line, electric means operated by said piston for actuating the first named valve, and a second electric means operated by one of said die members for actuating the second named valve.

11. In a die casting machine including complementary die members cooperating to provide a die cavity, one of said members being movable to open and close said cavity, a metal inlet communicating with said cavity in one of said members, a separable bi-sectional heat exchanger on said members having an air outlet passageway not less than 0.020 inch in thickness therein when closed communicating with said cavity, means for passing a cooling fluid in contact with said heat exchangers, a vacuum line connected to said passageway, a metal reservoir adjacent one of said die members, a metal injecting piston cylinder assembly communicating with the reservoir, valve means in said vacuum line operable by said movable die member for the closure of the vacuum line when the die members are separated but which is opened when the die members are closed, a second valve in the vacuum line which by-passes the first-mentioned valve, and a timer for operating both the second valve and the injection piston, said timer operating the second valve in sequence after the operation of said piston.

12. In a die casting machine including complementary die members cooperating to provide a die cavity, one of said members being movable to open and close said cavity, a metal inlet communicating with said cavity in one of said members, a separable bi-sectional heat exchanger on said members having a passageway therein when closed communicating with said cavity, means for passing a cooling fluid in contact with said heat exchangers, a first vacuum line connected to said passageway, a second vacuum line having a restriction therein communicating with the first named vacuum line, a

metal reservoir adjacent one of said die members, a cylinder communicating with said reservoir and said metal inlet to said cavity, valve means in said first vacuum line to control the application of vacuum, and a second valve means in said second vacuum line to vary the amount of the vacuum.

13. A die casting machine comprising a fixed die member and a confronting reciprocal die member having a mold cavity therein, one of said die members having a metal inlet passageway therein communicating with said mold cavity, a metal outlet passageway for the mold cavity formedibetween the die members which varies in thickness from A to inch a separable heat exchanger embodying separable sections mounted respectively on each die member, said sections forming a space in the mating faces thereof constituting a molten metal passageway not less than 0.020 inch in thickness when said sections are closed which connects to the metal outlet passageway, each section of said heat exchanger having channels therein adjacent said passageway between the cooling members for the circulation of a coolant liquid to solidify molten metal therein after the mold cavity is filled, said heat exchanger embodying an external jacket formed of a material of lower heat conductivity than said die members, thermal insulating means disposed between each heat exchanger and its die member to suppress the flow of heat from the die member to the heat exchanger, and an internal body formed of a material of high heat conductivity, whereby the molten metal will flow through said heat exchanger and be chilled therein before it solidifies in said die cavity.

14. A die casting machine comprising a fixed die member and a confronting reciprocal die member having a mold cavity therein, one of said die members having a metal inlet passageway therein communicating with said mold cavity, a heat exchanger embodying divided separable cooling members having an exterior portion formed of a metal of lower heat conductivity than said die members, and an interior portion of a material of higher heat conductivity than said die members, each cooling member thereof being attached to each die memher, the interior portion of said cooling member having a Wave-like molten metal outlet passageway not less than 0.020 inch in thickness when the cooling members are closed with said die members, means in said heat exchanger for rapidly removing from said passageway heat to reduce the temperature thereof below the temperature of said die members, the engaging areas of said cooling members with said die members being insulated by air gaps to suppress the fiow of heat from the die members into the cooling members.

15. In a die casting machine including complementary die members having recesses in the mating faces thereof defining a die cavity, one of said die members being movable towards and away from the other die member to open and close said cavity, means for injecting molten metal under pressure into the die cavity, a separate metal cooling member secured to each die member, means for suppressing the flow of heat from the die members into the metal cooling members, at least one of said metal cooling members being movable into engagement with and away from the other metal cooling member during movement of the die member to which it is secured, a passageway between the engaged metal cooling members connected to a vacuum duct and to the die cavity, and means for cooling the metal cooling members to solidify metal in said passageway before the metal solidifies in the die cavity, separate means on each die member forming therebetween a second passageway connected to the die cavity, one of said means being movable with the movable die member, said second passageway also extending between metal cooling members, and means connected to the second passageway to measure the pressure in the die cavity during the filling of the die cavity with metal.

16. A die casting machine as defined in claim 15 in which the separate means are each a metal cooling member maintained at a lower temperature than the die members.

17. The improved process for forming die castings by the high-pressure injection of metal into gas-impervious hot molds having die cavities provided with passage means for the removal of gas from and the forcing of molten metal into the die cavities of the molds and in which a part of the passage means for the removal of gas is tortuous and formed between cooling members which are insulated from the molds, which comprises removing gas from the die cavities through the passage means in advance of the molten metal being forced into the die cavities, cooling the tortuous part of the passage means to a temperature below the temperature of the die cavities by the circulation of a cooling fluid in heat exchange contact with the cooling members, after filling the die cavities forcing metal into the tortuous passage means and freezing the metal therein to form a plug and stop the further flow of molten metal from the die cavities.

18. In the process of claim 17, maintaining a vacuum in the passageway to evacuate the die cavity as the die cavity is being filled.

19. In the process of claim 17, measuring the pressure in the die cavity through a separate passageway.

References Cited in the file of this patent UNITED STATES PATENTS 1,606,236 Kadow Nov. 9, 1926 2,210,544 Galloway Aug. 6, 1940 2,243,835 Brunner et al. June 3, 1941 2,248,868 Hanawalt July 8, 1941 2,371,604 Brennan Mar. 20, 1945 2,610,372 Schraeder Sept. 16, 1952 2,785,448 Hodler Mar. 19, 1957 2,786,234 Beyer Mar. 26, 1957 FOREIGN PATENTS 302,974 Switzerland Ian. 17, 1955 UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent No 3 OO6 O43 0ctobegygl 1961 Walter M Goldhamer d thaterror appears in the above numbered pat- It is hereby certifie aid Letters Patent should read as ent requiring correction and that the s corrected below.

Column 7 line 58 for "forming". read forcing *1,

Signed and sealed this 3rd day of April 1962.,

(SEAL) Attest:

ERNEST W. SWIDRR Attesting Officer DAVID L. LADD Commissioner of Patents

Images