US3292218A - Automatic metal injection system - Google Patents

Description

7 Dec. 20, 1966 J. A. KOZMA, JR 3,292,218

AUTOMATIC METAL INJECTION SYSTEM Filed April 29, 1965 FLUID SOURCE INVENTORY 50A 2. JOSEPH A.KOZMA JR.

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ATTORNEYS United States Patent AUTOMATIC METAL INJECTION SYSTEM Joseph A. Kozma, Jr., Dearborn, Mich., assignor to J. A. Kozma Company, Deal-born, Mich., a corporation of Michigan Filed Apr. 29 1965, Ser. No. 451,759 6 Claims. (Cl. 22-70) The present invention relates to metal die casting and more particularly to a means of transferring molten metal from a melting furnace to the receiving chamber of a die casting or extruding machine.

Heretofore various methods have been used to transfer molten metal from a melting furnace to a die casting machine or the 'ke. The molten metal may be hand ladled but this is very slow and results in non-uniform quality as well as non-uniform s'hot sizes.

Another method that has been used is to evacuate the mold in the die casting machine so that atmospheric pressure acting upon the furnace bath will cause the molten metal to flow into the receiving chamber of the machine through a connecting tube. Such a method has the disadvantage that if the timing of the opening and closing of the valves used to produce the evacuation is off even slightly serious difiicu'lty will arise. Either too little molten metal will be delivered to the die resulting in an incomplete end product or too much molten metal will be delivered which produces the danger of the hot metal being forced up into the valve tending to damage or destroy it. Further, the system must be airtight because any leakage will permit air to be drawn into the die instead of the molten metal. This is a difiicult problem because it is practically impossible to keep the die airtight under operating conditions.

Another similar method of transferring the molten metal is by applying compressed air to the surface of the metal in the bath. This method results in non-uniform shot sizes. Any variation in air pressure changes the amount of metal transferred. Any variation in the furnace bath level also changes the amount of metal transferred by a given air pressure and it is impossible to hold the bath level in the furnace uniform during operation.

Still another method is disclosed and claimed in US. Patent No. 3,077,015 issued February 12, 1963. This patent describes a method. in which an automatically operated ladle is used to transfer the molten metal from the melting furnace to the receiving chamber of a die casting or extending machine. While such a method has proven to be quite satisfactory it has the disadvantage that it is difficult to change the size of the shot of molten metal to be delivered. To change the shot size either the ladle must be changed or modified or an insert must be installed or removed.

The present invention provides a system of transferring metal from the melting furnace to the die casting or extruding machine which overcomes the disadvantages of the aforementioned previously used methods. Means are provided for readily adjusting the shot size and this may be accomplished without disrupting the operation of the die casting or extruding machine.

It is an object then of the present invention to increase the operating time of die casting machines and the like by providing a metal injection system having means for readily adjusting the size of the metal shot to be delivered to the machine.

It is still another object of the present invention to improve metal casting by providing means delivering a uniform shot of molten metal from beneath the oxidized surface of the metal bath to the metal casting machine.

Still further objects of the present invention will readice ily occur to one skilled in the art to which the invention pertains upon reference to the following drawings in which like reference characters refer to like parts throughout the several views and in which,

FIG. 1 is a diagrammatic illustration of a metal injection system of the present invention, and

FIG. 2 is an electrical diagram illustrating a preferred or typical control system for the present invention.

Now referring to the drawings for a more detailed description of the present invention, a preferred system is illustrated diagrammatically in FIG. 1 as comprising a melting or holding furnace 10 partially filled with molten material 12 such as metal or the like.

A die casting or extruding machine 13, only a portion of which is shown is provided with a die cavity 11 and a shot sleeve 14 registering with the die cavity 11. A plunger 15 is carried in the shot sleeve 14 and is operable upon being actuated to move axially within the shot sleeve 14 to deliver molten metal from the shot sleeve 14 to the die cavity 11. A shaft 16 is provided on the plunger 15 and microswi-tches 1718 are positioned to be engaged by the plunger 15 and a cam portion 19 provided on the shaft 16 as will be described in more detail below.

A preferred metal injection means for delivering molten metal from the furnace 10 to the shot sleeve 14 of the machine 13 is illustrated in FIG. 1 as comprising a reservoir member 20 preferably constructed of any suitable refractory material and positioned within the furnace 10 beneath the level of molten metal 12. The

. reservoir 10 is provided with a chamber 22 and a piston 24 is axially slidably carried in the chamber 22. A delivery tube 25 provides communication between the chamber 22 and the shot sleeve 14 of the machine 13. Intake ports 26 are annularly spaced about the reservoir 20 and provide communication between the furnace 20 and the chamber 22. Larger ports 27 are provided in reservoir 20 above the ports 26.

A housing 28 is secured to the reservoir 20 in axial alignment with the chamber 22 and extends upwardly therefrom exteriorly of the furnace 10. A top plate 29 covers the exterior end of the housing 28 and provides the means for supporting a power cylinder 30. vThe power cylinder 30 is provided with a piston 32 connected by an extended shaft 34 to the piston 24 so that axial movement of the piston 32 produces a corresponding axial movement of the piston 24.

The operating fluid from the power cylinder 30 enters and exits from ports 36A-36B to actuate the piston 32 and may be either compressed air or hyraulic fluid. The operating fluid is delivered to the power cylinder 30 from a fluid source 37 and through a 4-way valve 38.

A rod 40 is secured to the shaft 34 by a bracket 42 to extend substantially parallel with the shaft 34 and to be axially movable therewith.

A mounting block 41 is secured to the power cylinder 30 and the rod 40 extends through the top plate 29 adjacent the mounting block 41. A guide 43 is mounted on the mounting block 41 to maintain the rod 40 parallel with the shaft 34. A cam portion 44 is provided at the upper end of the rod 40.

A threaded rod 46 is journalled at each end in suitable mounting brackets 47 secured to the mounting block 41 and is provided at its upper end with an adjusting knob 48. A microswitch 50 is carried on the rod 46 by means of an internally threaded block 52 so that rotation of the rod 46 by the knob 48 produces movement of the microswitch 50 axially along the rod 46. The microswitch is positioned to be actuated by the cam portion 44 of the rod and is connected by flexible leads 56 to a terminal block 54 carried by the mounting block 41. A microswitch 57 is carried by the mounting block 41 in a position to be engaged by the free end of the rod 40. A blocking means 59 is carried by one of the brackets 47 to selectively prevent the rod 44 from rotating so as to lock the microswitch 50 in a desired axial position. A calibrated scale 58 is carried on the mounting block 41 adjacent the rod 44 to indicate the position of the microswitch 50.

A microswitch 62 is provided on the machine 13 and is actuated when the die cavity 11 isopen or closed.

The operation of the valve 38 is preferably controlled by electrically actuated solenoids 64 and 66 as shown diagrammatically in FIG. 1. Energization of the solenoid 64 actuates the valve 38 to a position providing fluid under pressure to the port 36B and exhausting pressure from the port 36A to move the piston 32 upwardly in the power cylinder 30. Similarly, energisation of the solenoid 66 actuates the valve 38 to a position providing fluid under pressure to the port 36A and exhausting pressure from the port 3613 to move the piston 32 downwardly in the power cylinder 30.

A preferred electrical system for energizing the solenoids 64 and 66 in the proper sequence is illustrated schematically in FIG. 2. The solenoids 64 and 66 are connected in parallel across a suitable power source 68 and through a manual switching means 70. A control circuit 72 for energizing the solenoid 66 and a control circuit 74 for energizing the solenoid 64 are also connected in parallel across the power source 68.

The control circuit 72 includes the microswitches 17, 50

and 62 series connected with a relay 76. A relay contact 78 is connected in series in the control circuit 72 and is actuated to a closed position by controls (not shown) provided on the machine 13. The switch 62 is normally open and is closed upon the die cavity 11 being closed. The switch 17 is normally open and is actuated to a closed position upon the plunger 15 being moved to its retracted position. The switch 50 is normally closed and is actuated to an open position by the cam portion 44 of the rod when the piston 24 is in a down position.

Thuswith the piston 24 in the upper position and the plunger 15 in the retracted position and the die casting machine 13 ready to receive a shot as indicated by the closed contact 78 the relay 76 will be energized. Energization of the relay 76 actuates a contact 80 to hold the control circuit 72 and a contact 82 to energize the solenoid 66. Energization of the solenoid 66 actuates the power cylinder 30 as described above to move the piston 24 downwardly in the reservoir 20. Downward movement of the piston 24 will force molten metal 12 .from the reservoir 20 through the delivery tube 25 and to the shot sleeve 14.

It is apparent that the extent of axial downward movement of the piston 24 which is permitted will determine the amount of molten metal and thus the shot size which is delivered to the shot sleeve 14. When the piston 24 has moved downwardly sufiiciently to bring the cam portion 44 of the rod 40 into engagement with the switch the control circuit 72 will be opened and the solenoid 66 will be de-energized and the valve 38 will move to a neutral or holding position. The point at which the piston 24 will be stopped on its downward movement determines the shot size and this can be adjusted by adjusting the axial position of the switch 50 along the rod 46.

Once the desired amount of metal has been delivered to the shot sleeve the plunger 15 is actuated to deliver the shot to the cavity 11. Forward movement of the plunger 15 actuates the normally open microswitch 18 through the rod 40 upon upward movement of the piston 24 to open the circuit 74 upon the piston 24 reaching the desired upper position. De-energization of the solenoid 64 :returns the valve 38 to its holding position.

The switches and 92, shown in FIG. 2 as shunting the relay contacts 88 and 82 respectively, are provided to permit manual operation of the piston 24.

The switch 50 has a separate normally open contact 50A which is closed when the piston 24 is in its lowermost 1 position.

This contact 50A can be connected .in the die 1 casting machine circuit to cause the plunger 15 to be actu- The calibrated scale 58 indicates the 1 shot size which will be delivered at any position of the microswitch 50 and the clamping means 59 locks the 1 microswitch 50 at the desired position.

The ports 27 insure that the level of the molten metal in the furnace 10 will also be maintained in the reservoir 20.:

This insures that on the upward stroke of the piston 24;

no air will enter the reservoir 20 to form oxides and that the shot delivered to the machine 13 will be entirely from beneath the surface of the molten metal.

Piston rings cannot as a practical matter be used on the piston 24. Some metal therefore will pass upwardly between the piston 24 and the reservoir 20 as the piston 24 ismoved downwardly but the molten metal above the: piston 24 provided by the ports 27 insures that this metal.

will not squirtupwardly.

It is apparent that with the metal injection system of.

the present invention the shot size can be readily varied without even the necessity of shutting down the die casting or extruding machine. nace has no effect on the size of the shot as long as the furnace bath is high enough to fill the reservoir.

The level of the bath in the fur- Further, since the metal shot is taken entirely from beneath the surface of the molten metal, oxides present on the,

surface of the metal will not be delivered to the casting or extruding machine.

It is also apparent that although I have described but a single embodiment of the present invention many changes I and modifications can be made without departing from: the spirit of the invention or the scope of the appended 3 claims.

I claim:

1. A metal injection system for delivering molten metal from a furnace to a die casting machine or the like comprising,

(a) a reservoir member adapted to be carried in the furnace beneath the level of molten metal therein and having a chamber and intake ports communicating therewith, (b) a piston axially reciprocally slidably carried in said chamber,

(c) a delivery tube connecting said chamber with the,

receiving chamber of the die casting machine or the like,

(d) means for axially moving said piston in said chamber from an initial position, and

(e) means associated with. said piston and operable upon a selectively variable displacement of said pis- A ton from said initial position to render said moving means ineffective so that a selectively variable shot of molten metal is delivered from said reservoir to the receiving chamber of said machine.

2. In combination with a furnace for holding molten metal and the like and a casting machine, an injection system for delivering metal from said furnace to said 1 machine comprising.

(a) said reservoir carried in said furnace beneath the.

level of molten metal therein,

(b) said reservoir being provided with a chamber,

(c) a delivery tube communicating with one end of said chamber and connected with said machine,

(d) a piston axially slidably carried at the end of said chamber opposite said delivery tube,

(e) an intake port provided in said reservoir intermediate said delivery tube and the opposite end of said chamber,

(f) means axially slidably moving said piston from an initial position in said chamber toward said delivery tube,

(g) means connected with said piston and acutated by a predetermined displacement of said piston toward said delivery tube for de-energizing said moving means, and

(b) means operable to selectively vary the stroke of said piston whereby the size of the charge of molten metal delivered to said machine may be selectively varied.

3. The combination as defined in claim 2 and in which said last mentioned means comprises,

(a) switching means operably connected with said piston moving means and operable upon being engaged to de-energize said piston moving means whereby movement of said piston will be stopped,

(b) means carried by said piston and engaging with said switching means at a predetermined axial position of said piston,

(c) and means for selectively varying the position of said switching means whereby said piston can be stopped at any desired position.

4. The combination as defined in claim 3 and including a plunger carried in said delivery tube, a normally open switching means connected with said plunger and operable upon being closed to move said plunger in said delivery tube in a direction toward said machine, and means closing said last mentioned switching means at a predetermined axial position of said piston.

5. The combination as defined in claim 4 wherein the closing of said last mentioned switching means is operable to actuate said piston moving means to return said piston to said initial position in said chamber.

6. A metal injection system for transferring controlled charges of molten metal from a furnace to a casting machine, comprising:

(a) a reservoir member adapted to be carried in the furnace beneath the level of molten metal therein;

(b) said reservoir having a chamber and an intake port providing communication between the furnace and said chamber;

(c) a piston axially slidably carried in said chamber and means selectively reciprocally moving said piston past said intake port;

((1) a delivery tube connecting said chamber with the machine whereby upon movement of said piston past said intake port, a charge of molten metal is forced through said delivery tube to said machine;

(e) means actuated by said piston passing a predetermined position past said intake port for stopping the movement of said piston; and

(f) means for selectively varying the stroke of said piston whereby the size of the charge of molten metal delivered through said delivery tube may be varied.

References Cited by the Examiner UNITED STATES PATENTS 6/1941 Brunner et al. 2/1964 Morton 2268

Claims (1)

1. A METAL INJECTION SYSTEM FOR DELIVERYING MOLTEN METAL FROM A FURNANCE TO A DIE CASTING MACHINE OR THE LIKE COMPRISING, (A) A RESERVIOR MEMBER ADAPED TO BBE CARRIED IN THE FURNANCE BENEATH THE LEVEL OF MOLTEN METAL THEREIN AND HAVING A CHAMBER AND INTAKE PORTS COMMUNICATING THEREWITH, (B) A PISTON AXIALLY RECIPROCALLY SLIDABLY CARRIED IN SAID CHAMBER, (C) A DELIVERY TUBE CONNECTING SAID CHAMBER WITH THE RECEIVING CHAMBER OF THE DIE CASTING MACHINE OR THE LIKE, (D) MEANS FOR AXIALLY MOVING SAID PISTON IN SAID CHAMBER FROM AN INITIAL POSITION, AND (E) MEANS ASSOCIATED WITH SAID PISTON AND OPERABLE UPON A SELECTIVELY VARIABLE DISPLACEMENT OF SAID PISTON FROM SAID INITIAL POSITION TO RENDER SAID MOVNG MEANS INEFFECTIVE SO THAT A SELECTIVELY VARIABLE SHOT OF MOLTEN METAL IS DELIVERED FROM SAID RESERVOIR TO THE RECEIVING CHAMBER OF SAID MACHINE.

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