US3121926A - Vacuum system for die casting - Google Patents

Description

Feb. 25, 1964 G. R. MORTON 3,121,926

VACUUM SYSTEM FOR DIE CASTING Filed Nov. 4, 1957 GLEN R. MORTON INVENTOR.

FIG.2. 4.1% I

United States Patent ()fifice 3,121,926 Patented Feb. 25, 1964 3,121,926 VACUUM SYSTEM FOR DIE CASTING Glen R. Morton, 7025 S. Sarpy, Omaha, Nebr. Filed Nov. 4, 1957, Ser. No. 694,315 Claims. (Cl. 22-68) This invention relates to die-casting machines and more particularly it is an object of this invention to provide a more efficient die-casting system for vacuum die-casting.

I am aware that others have invented vacuum die-casting systems in which valves have been used to close off vacuum outlet grooves in the dies. However, I have discovered by experiment that none of these provide a sufficiently well timed and rapid closing of the vacuum groove valve to make them operable and reliable from the standpoint of preventing large quantities of molten metal from passing into the vacuum system when using a large opening out of the cavity.

It is an object of my invention to provide a vacuum system for die casting machines that makes it possible to have an opening leading from the cavity of the die to the vacuum source which opening has a capacity greater than the rate of displacement of the metal coming into the cavity at the high speed necessary to prevent chilling of the metal at any part before the cavity is completely filled, thus permitting a higher vacuum and sustained during the casting cycle.

A particular object is to provide a cavity in connection with the vacuum groove to utilize the directional flow of the metal in case of too much metal accidently being ladled or injected into the shot chamber, the metal will flow on into this cavity instead of into the vacuum supply line, etc. This was a major source of trouble in some of the systems that the industry has tried to use.

Another object is to use an accumulated source of hydraulic pressure electrically controlled for the instantaneous closing of the vacuum groove valve in the die.

Another object is to provide a vacuum system which uses an accumulated vacuum for making available vacuum in quantity that is not dissipated in a wasteful manner.

A further object is to provide a vacuum system for a cold shot chamber machine which makes possible a higher vacuum than heretofore for exhausting hydrogen gas caused by moisture in the metal, thereby making possible pressure tight castings even when the humidity is as high as 100%.

Another object is to provide a metered flow or" metal into the shot chamber under vacuum through small metered holes for regulating flow, for slowing down metal flow to an extent making possible regulation of timing and further including a means for time delay between application of the vacuum to the cavity and forward motion of the plunger to permit metal in sufficient but not excessive quantities to be driven into the shot chamber by atmospheric pressure as a result of the vacuum drawn on the cavity and shot chamber.

A further object is to eliminate aluminum oxide in the castings which is caused by breaking the surface film of the molten metal by ladling, etc. This aluminum oxide in the castings make them very diflicult to machine as the oxide dulls the tools.

By feeding the metal into the shot chamber from beneath the surface in the bath whereby the metal is not in contact with air until casting is complete. A particular object is to provide a system of timing of the closing of a valve in the bleeder groove sufliciently soon after the cavity has been filled to sufiiciently prevent passage of metal past this valve to avoid the problem of the need for shutting down of a machine for the cleaning of the vacuum line which leads from the bleeder groove.

In the drawings:

FIGURE 1 is a diagrammatic view of a portion of a die casting machine with this invention attached, many parts being shown in section;

FIGURE 2 is a view of the face of the movable die plate of this invention.

In FIGURE 1 a molten metal bath and furnace 10 delivers metal through an extension 12 having a housing 14 to a ceramic intake tube 16 having a closed lower end 18 provided with intake openings 20 one or" which is shown in FIGURE 1. The openings 20 are of small size for metering flow to a speed sufficiently slow that other later described parts of the machine can be timed proportionately thereto.

The extension 16 has its lower end beneath the surface 22 of molten metal in the bath 10.

The extension 16 is suitably attached to the underside of the shot chamber 34) and is in communication therewith through an opening 32 forwardly of a rearwardmost position of a plunger 34 urged by plunger rod 36 as operated by a piston 38 in a cylinder 40 supported by pedestal 42, the cylinder 441 being conventional and operated by hydraulic lines 44 at each end thereof.

Metal from the interior 50 of the shot chamber 30 can pass through a groove 82 in the die then through a more constricted groove 84 in the movable die 85 thence through into the cavity 86 through a constricted groove 88 into a vacuum groove 90 past a vacuum valve 92 adapted to close the groove 9% and prevent molten metal from passing through the groove 90 into a connected vacuum outlet passage 94, which latter is at the top of the movable die block 85. It will be seen that the vacuum groove 90 can also be called an outlet groove inasmuch as it serves as an outlet for air in the die cavity.

The movable die block 85 further has a molten metal trap 96 in the form of an indentation into the die section 85 disposed on the other side of the passage 94 from the vacuum groove 90 or otherwise in a position beneath the passage 94 whereby molten metal tends to collect in the trap 96 rather than passing out through the passage 94. The entrance of the trap is in alignment with the direction of metal flow in the groove and the groove extends beyond the entrance to the trap in a direction transverse to the direction of the extending of that portion of the groove which is before the entrance to the trap with respect to the direction of metal flow.

A vacuum line 98 is connected to the passage 94 by having its lower end secured by a bolt 99 to the stationary die section 87 but not secured to the movable die section 85.

The stationary die section 87 has cavities and the like complemental to those of the movable die section as is usual.

The vacuum line 98 extends to a valve 102 controlling flow from a vacuum supply line 104 leading to a source of accumulated vacuum for instant substantially undissipatable vacuum supply.

The valve 102 is controlled by a solenoid 208 which has one of its terminals connected by a wire to a terminal 112 of a solenoid 116.

The solenoid 116 is part of the standard equipment of a die casting machine and is the solenoid which actuates the timer of the machine when the die locks close, the said timer being conventional and not shown.

The solenoid 116 receives energy to its terminal 112 through a line 120 extending to circuits of a machine not shown and the other terminal 124 of the solenoid receives power from a line 128 extending from circuits of the machine, not shown.

A Wire extends from the terminal 124 to a terminal 144 of a switch 146. The switch 146 has a rocker arm 148 disposed in a position to be actuated by a finger 150 fixed to the plunger rod 36 at times when the plunger rod has reached a forward position in which the plunger 34 has passed across the opening 32 and has traveled substantially to its farthest forward point.

When the finger in forward travel strikes the rocker arm 143 contact is made between terminals and 144 of the switch 146, by means of a contact member 166 of the switch.

This connects the Wire 1140 in circuit with a wire 170 which latter leads to a solenoid 174 of this invention which controls the valve 178 which latter permits flow of hydraulic fluid through a line 180 into a cylinder 182 for driving a piston 184 to the right for causing the valve 92, which is a rod attached to the piston 184, to close.

The hydraulic fluid entering the valve 178 comes through a line from a source of accumulated hydraulic pressure for making possible instantaneous action.

The other terminal of the solenoid 174 is connected by a wire 196 to the terminal 112 of the solenoid 116.

Oil returns from the valve 198 through a line 200 to a reservoir not shown. Oil returns from the cylinder 182 during a motion of the piston 184 to the right through a hydraulic line 206, which latter connects to the right hand end of the cylinder 182 while the line 100 connects to its left end.

The solenoid 208 which operates the vacuum valve 102 receives energy from the same terminals 112 and 124 and so the valve 162 is only energized when the die is closed and as now described.

A line 212 connects one terminal of the solenoid 208 with the wire 196 leading to the terminal 112 and a wire 218 leads from the other terminal of the solenoid 208 to a terminal 220 on the switch 146 which latter is placed in electrical communication with a terminal 144 of the switch 146 by the contact member 166 at times when the rocker arm is in the full line position shown in FIG- URE 1.

The circuit operates as follows:

The solenoid 208 that actuates the vacuum valve 102 and the solenoid 174 that actuates the valve 178 that allows oil to How to the cylinder 182 to move the valve 92 to close the vacuum groove 90 are supplied by the same source, namely the wires 120 and 128 that energize the timer, not shown, that starts the cycle after the die has been closed.

When the die is locked closed a switch, not shown, is closed by the locking of the toggles of the machines, also not shown. And also not shown is a hand operated switch which is closed by the operator when hand ladling, thus energizing the vacuum solenoid 208 through the switch 146, and also starts the timer, not shown, which times out and starts the injection plunger 34 by means of the hydraulic cylinder 40 after delaying a sufficient time to allow the correct amount of aluminum zinc or other alloy to enter the shot chamber 30 under atmospheric pressure due to vacuum in the cavity and shot chamber.

The double switch 146 is actuated by the finger 150 on the injection plunger rod 36 as it moves forward, forcing the metal into the cavities.

The switch 146 is adjustable so it cuts the current from the vacuum valve solenoid 20S and makes the circuit to the solenoid 174 that actuates the valve 178 allowing hydraulic fluid to close the valve 92 shutting off the vacuum groove 90 and preventing molten metal from flowing into the vacuum system through the vacuum line 98.

The switch 146 is set so that the vacuum valve 102 is shut off and the valve 92 and the vacuum groove is also shut off sufiiciently soon after the cavity is completely filled to sufliciently prevent passage of metal past the valve 92 to avoid the problem of necessity for shutting down the machine for the cleaning of the vacuum line.

As soon as the die starts to open this supply of current is cut by a snap-switch, not shown, and as the die unlocks; at the same instant the die opening solenoid 270 is energized. This same current energizes the solenoid 272 that actuates the valve 178 for moving the valve 178 into a position of opposite effect to that of the solenoid 174 whereby oil under pressure fiows through the line 206 to retract the piston 184 and valve 92 opening the vacuum groove 90 completely.

The casting is then ejected in the conventional manner. This invention makes use of the solenoid 270 which is a conventional part of the machine and which actuates the opening of the die for properly timing the solenoid 272.

In using my system the operator only has to retract the ejectors of the machine, which are conventional parts not shown, in the usual manner and thereafter the die closes and the cycle is repeated.

It will be seen that the metal can be forced into the cavity at high speed without decreasing the vacuum as the vacuum is pulled at a greater speed than the metal is injected.

As thus described it will be seen that this invention provides the objectives of greater efficiency, prevention of metal passage into the vacuum lines, and better castings as above set forth.

As thus described it will be seen that this invention provides a vacuum die casting system which is well timed, operates without clogging, eliminates aluminum oxide, removes the hydrogen gas during high humidity, because of the high vacuum that can be obtained. Permits faster production by the elimination of ladling and the accumulation of thin flash sticking to the die face in the bleeder groove, which is a problem with thin bleeds whether using vacuum or not.

From the foregoing description, it is thought to be obvious that a vacuum casting machine constructed in accordance with my invention is particularly well adapted for use, by reason of the convenience and facility with which it may be assembled and operated, and it will also be obvious that my invention is susceptible of some change and modification without departing from the principles and spirit thereof, and for this reason I do not wish to be understood as limiting myself to the precise arrangement and formation of the several parts herein shown in carrying out my invention in practice, except as claimed.

I claim:

1. In a die casing machine, the provision of a die section having an air outlet groove therein leading from the die cavity means comprising a vacuum line for drawing a vacuum on said groove, a shot chamber in communication with said die cavity, a reciprocating shot plunger in said shot chamber, a vacuum groove shut 01f valve mounted in said die section at said vacuum groove for the sudden closing of said groove to prevent escape of molten metal into said vacuum line, a hydraulic cylinder assembly mounted on said machine and having a piston, means drivably connecting said piston with said groove shut-off valve, a source of accumulated hydraulic pressure, means comprising a hydraulic pressure control valve for placing said hydraulic pressure source in communication with said hydraulic cylinder to close said groove shut-off valve, an electrically controllable means for controlling said hydraulic pressure control valve, a source of electrical power, a switch means on said machine operating in response to forward movement of said plunger, and a circuit connecting said switch means, said electrical power source, and said electrically controllable means whereby said electrically controllable means opens said pressure control valve for the closing of said groove shut-off valve when said plunger advances and said switch is operated thereby, the timing of the closing of said groove shut-off valve being sufiiciently soon after the cavity has been filled to sufiiciently prevent passage of metal past the groove shut-off valve to avoid the problem of shutting down the machine for the cleaning of metal from said vacuum line and for providing castings of great density.

2. The combination of claim 1 in which said second controllable means is specifically a solenoid.

3. The combination of claim 1 in which a vacuum supply line valve is disposed in said vacuum supply line, controllable means for operating said vacuum line valve, and said switch means and said circuit operating said controllable means for the opening of said vacuum supply line valve after said die is closed and as said shot plunger moves into said shot chamber.

4. The combination of claim 1 in further combination with: said shot cylinder having an intake opening, an intake tube in communication with said intake opening and extending downwardly into said bath sufiiciently to be beneath the metal in said bath, said intake tube having an opening in its lower end of a small size for metering flow.

5. In a die casting machine the provision of a die section having an air outlet groove leading from the die cavity, a shot chamber in communication with said die cavity, a reciprocating shot plunger in said shot chamber, an air outlet groove shut-off Valve mounted in said die section at said air outlet groove for the sudden clos ing of said groove to prevent escape of molten metal from said groove, a hydraulic cylinder assembly mounted on said machine and having a piston, means drivably connecting said piston with said groove shut-off valve, a source of accumulated hydraulic pressure, means comprising a hydraulic pressure control valve for placing said hydraulic pressure source in communication with said hydraulic cylinder to close said groove shut-off valve, an electrically controllable means for controlling said hydraulic pressure control valve, a source of electrical power, switch means on said machine operating in response to forward movement of said plunger, and a circuit connecting said switch means, said electrical power source, and said electrically controllable means whereby said electrically controllable means opens said pressure control valve for the closing of said groove shut-off valve when said plunger advances and said switch is operated thereby, the time of the closing of said groove shut-oil valve being sufficiently soon after the cavity has been filled to sufficiently prevent passage of metal past the groove shut-oll valve to avoid loss of metal through said groove and to permit escape of air from the cavity during the filling of the cavity with metal for providing castings of great density.

6. The combination of claim 5 in which said second controllable means is specifically a solenoid.

7. The combination of claim 5 which further comprises the presence in said die cavity of an overflow trap cavity in communication with said groove and having an entrance in alignment with the direction of metal flow in said groove, said groove extending beyond the entrance to said trap in a direction transverse to the direction of the extending of that portion of said groove which s before the entrance to said trap, whereby said trap is adapted to receive molten metal in the event the flow of metal reaches the shut-oif valve before the shut-off valve closes.

8. In a die casting machine, a sectional die having an air outlet groove leading from its cavity, a vacuum conduit communicating with the air outlet groove and adapted to be in communication with a vacuum producing means, a molten metal supply conduit communicating with the cavity of said die, a vacuum groove shut-oil valve slidably mounted in said die and located at its air outlet groove for suddenly closing said air outlet groove to prevent the escape of molten metal into said vacuum conduit, a two-way hydraulic cylinder unit having a piston operatively connected to said groove shut-off valve, a source of accumulated hydraulic pressure, means comprising a hydraulic pressure control valve for placing said hydraulic pressure source in said hydraulic cylinder at either side of the piston of said hydraulic cylinder unit, an electrically operated means for actuating said hydraulic pressure control valve, a movable means on said machine indicating the time interval the cavity of the die is substantially filled with molten metal, a switch actuated by said last mentioned means, a source of electrical power, and a circuit connecting said switch means, said source of electrical power, and said electrically operated means, whereby said electrically operated means actuates said pressure control valve for closing said shut-off valve when said switch is actuated and closed by said movable member, the timing of the closing of said groove shut-off valve being sufficiently soon after the cavity has been filled with molten metal to sufiiciently prevent passage of metal past the groove shut-01f valve, thereby preventing the escape of molten metal into the vacuum conduit and also providing castings of great density.

9. In a die casting machine, a sectional die having an air outlet groove leading from its cavity, a vacuum conduit communicating with the air outlet groove and adapted to be in communication with a vacuum producing means, a molten metal supply conduit communicating with the cavity of said die, a vacuum groove shut-off valve slidably mounted in said die and located at its air outlet groove for suddenly closing said air outlet groove to prevent the escape of molten metal into said vacuum conduit, a two-way hydraulic cylinder unit having a piston operatively connected to said groove shut-off valve, a source of accumulated hydraulic pressure, means comprising a hydraulic pressure control valve for placing said hydraulic pressure source in said hydraulic cylinder at either side of the piston of said hydraulic cylinder unit, an electrically operated means for actuating said hydraulic pressure control valve, a movable means on said machine indicating the time interval the cavity of the die is substantially filled with molten metal, a switch actuated by said last mentioned means, an electrically actuate-d valve in said vacuum conduit, a source of electrical power, and a circuit connecting said switch means, said electrically actuated valve, said source of electrical power, and said electrically operated means, whereby said electrically operated means actuates said pressure control valve for closing said shut-oil valve when said switch is actuated and closed by said movable member, the timing of the closing of said groove shut-01f valve being sufficiently soon after the cavity has been filled with molten metal to sufficiently prevent passage of metal past the groove shut-oil? valve, thereby preventing the escape of molten metal into the vacuum conduit and also providing castings of great density.

10. Apparatus for casting articles in which a vacuum is used for pulling die casting material into an article cavity and maintained fully until the cavity is at least substantially loaded, said apparatus comprising a split die having at least two sections and including a die-casting material inlet, an article cavity, and a vacuum passageway communicating with said cavity; a shot cylinder communicating with said die-casting material inlet and having an opening therein; a feed tube coupling said opening with a supply of die-casting materiaLsaid feed tube having an apertured end adapted to be disposed in the supply for metering flow of die-casting material through said tube; a piston in said shot cylinder movable from a position where said opening communicates with said die cavity to a position where communication between said opening and the supply is interrupted and die-casting material in said shot cylinder is forced into said cavity by said piston to load said cavity; conduit means secured to one of said sections and slidably engaging the other of such sections for coupling said vacuum passageway, and thereby said cavity and said shot cylinder with a source of vacuum whereby die-casting material is drawn into said cavity by References Cited in the file of this patent UNITED STATES PATENTS During May 29, Daesen Mar. 26, Brummer ct al June 3, Halward Jan. 8, Schroeder Sept. 16, Venus Nov. 25, Babbitt Feb. 16, Holder Dec. 18, Holder Mar. 19,

Claims (1)

1. IN A DIE CASING MACHINE, THE PROVISION OF A DIE SECTION HAVING AN AIR OUTLET GROOVE THEREIN LEADING FROM THE DIE CAVITY MEANS COMPRISING A VACUUM LINE FOR DRAWING A VACUUM ON SAID GROOVE, A SHOT CHAMBER IN COMMUNICATION WITH SAID DIE CAVITY, A RECIPROCATING SHOT PLUNGER IN SAID SHOT CHAMBER, A VACUUM GROOVE SHUT OFF VALVE MOUNTED IN SAID DIE SECTION AT SAID VACUUM GROOVE FOR THE SUDDEN CLOSING OF SAID GROOVE TO PREVENT ESCAPE OF MOLTEN METAL INTO SAID VACUUM LINE, A HYDRAULIC CYLINDER ASSEMBLY MOUNTED ON SAID MACHINE AND HAVING A PISTON, MEANS DRIVABLY CONNECTING SAID PISTON WITH SAID GROOVE SHUT-OFF VALVE, A SOURCE OF ACCUMULATED HYDRAULIC PRESSURE, MEANS COMPRISING A HYDRAULIC PRESSURE CONTROL VALVE FOR PLACING SAID HYDRAULIC PRESSURE SOURCE IN COMMUNICATION WITH SAID HYDRAULIC CYLINDER TO CLOSE SAID GROOVE SHUT-OFF VALVE, AN ELECTRICALLY CONTROLLABLE MEANS FOR CONTROLLING SAID HYDRAULIC PRESSURE CONTROL VALVE, A SOURCE OF ELECTRICAL POWER, A SWITCH MEANS ON SAID MACHINE OPERATING IN RESPONSE TO FORWARD MOVEMENT OF SAID PLUNGER, AND A CIRCUIT CONNECTING SAID SWITCH MEANS, SAID ELECTRICAL POWER SOURCE, AND SAID ELECTRICALLY CONTROLLABLE MEANS WHEREBY SAID ELECTRICALLY CONTROLLABLE MEANS OPENS SAID PRESSURE CONTROL VALVE FOR THE CLOSING OF SAID GROOVE SHUT-OFF VALVE WHEN SAID PLUNGER ADVANCES AND SAID SWITCH IS OPERATED THEREBY, THE TIMING OF THE CLOSING OF SAID GROOVE SHUT-OFF VALVE BEING SUFFICIENTLY SOON AFTER THE CAVITY HAS BEEN FILLED TO SUFFICIENTLY SOON AFTER THE CAVITY HAS BEEN FILLED TO SUFFICIENTLY PREVENT PASSAGE OF METAL PAST THE GROOVE SHUT-OFF VALVE TO AVOID THE PROBLEM OF SHUTTING DOWN THE MACHINE FOR THE CLEANING OF METAL FROM SAID VACUUM LINE AND FOR PROVIDING CASTINGS OF GREAT DENSITY.

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