US3181211A - Die casting with ultrasonic vibration - Google Patents

Description

May 4, 1965 E, w. REARWIN 3,181,211

DIE CASTING WITH ULTRASONIC VIBRATION Filed May 16, 1962 2 Sheets-Sheet 1 FIG. I

POWER SUPPLY IN VEN TOR. EARLE W. REARWIN Jul $7 d M ATTORNEYS y 4, 1965 E. w. REARWIN 3,

DIE CASTING WITH ULTRASONIC VIBRATION Filed May 16, 1962 2 Sheets-Sheet 2 United States Patent 3,181,211 DIE CASTING WITH ULTRASGNlC VHERATKGN Earle W. Rearwin, High Point, N.C., assignor to Adams- Millis Corporation, High Point, N.C., a corporation of North Carolina Filed May 16, I962, Ser. Nan-195,078 6 Claims. (Cl. 22-68) This invention relates to die casting and, more particularly, to improvements in the construction of the die halves utilized in a die casting machine.

It isthe general object of the invention to provide a method and means of producing stronger and more dense products in the use of die casting machines.

A more specific object of the invention is to provide a die construction for die casting machines which incorporates an ultrasonic vibrator having a tip projecting through an opening in one of the die halves and into the die cavity so as to act upon the molten metal therein to produce the desired results set forth in the general object of this invention.

The drawings show preferred embodiments of the invention and such embodiments will be described, 'but it will be understood that various changes may be made from the constructions disclosed, and that the drawings and description are not to be construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawings:

FIG. 1 is a rather diagrammatic elevational view of that portion of a conventional die casting machine to which the improvements of the present invention may be added;

FIG. 2 is an enlarged plan view of the die assembly featuring the present invention;

FIG. 3 is a still further enlarged horizontal crosssectional view of the ejector-half of the die assembly shown in FIG. 2; and

FIG. 4 is a view generally similar to FIG. 3 but it illustrates a modified mounting arrangement for the ultrasonic vibrator.

Referring now to FIG. 1, it will be observed that the die casting machine to which the presently improved die construction maybe applied includes a movable platen and a stationary platen 12 which respectively support the ejector-half 14 and the cover-half 16 of the die construction or assembly. In keeping with conventional die casting machine construction, the movable platen I0 is mounted on a plurality of tie bars 18, 18 for closing movement toward the right which engages the die halves 14 and 16 and for return movement toward the left to the position shown which is the die open position.

As will be mentioned again, when the die halves are engaged or closed they cooperate to define a die cavity to which molten metal is introduced through a plunger sleeve 20 in the cover-half of the die. A plunger 22 is arranged to be reciprocated within the said sleeve by an hydraulic motor 24 so that molten metal introduced through an opening 26 to the sleeve in advance of the plunger 22 can be rammed into the die cavity under desired pressure. In further keeping with conventional die casting machine operating techniques, an electrical con trol panel 2% is mounted on the machine to provide switches that control solenoid operated valves that in turn control the operation of the hydraulic motor 24 for the plunger and an hydraulic motor (not shown) for reciprocating the movable platen 10 and its associated ejectorhalf 14 of the die. In one normal sequence of die casting machine operation, a switch at the control panel 28 is closed to effect closing of the die halves and then a switch is operated to advance the plunger 22 to move a charge ice of molten metal into the die cavity. Then, after a preselected time period, the plunger is retracted and the die halves are then opened. In this sequence of operations, the high-frequency vibrator incorporated in the die construction is preferably energized when theplunger is advanced and then de-energized when the plunger is retracted.

The improved die constructions illustrated in FIGS. 2, 3 and 4- include many conventional parts. Referring to the ejector-half 14, and as best shown in FIGS. 2 and 3, it is part of a subassembly which includes an anchor plate 39 which is detachably secured to the movable platen 10. Mold base plates 32, 32 are secured to the anchor plate 30 and project forwardly therefrom to support the ejectorhalf 14. Accordingly, when the platen It) is moved forwardly and rearwardly the ejector-half, the base plates and the anchor plate move with it. In the advanced or forward position of the platen 10, the ejector-half 14 en gages the cover-half 16 in face-to-face relationship and they cooperate to define the entire die cavity which is indicated generally in FIG. 2 by the reference number 34. This cavity includes the runner portion 36 which in keeping with conventional practice is ordinarily defined wholly within the ejector-half l4 and which is connected to the product cavity portion 38 at a gate 40, the product cavity 38 being defined partly in the ejector-half 14 and partly in the cover-half 16. In further keeping with conventional practice, cavity retainer blocks or inserts 42., 42 are provided, one in each die half, to facilitate the machining of the desired cavity surfaces.

In further keeping with conventional techniques, an ejector plate 44 is provided for the ejector-half 14, the ejector plate being secured to a back-up plate 46 by a series of machine screws such as the screw 48. A plurality of ejector pins 5%, 5th mounted in the ejector plate 44 and seated against the back-up plate 46 extend into suitable openings in the ejector-half 14 with their extending ends nearly flush with the surface of the cavity 38 formed in the ejector-half. Generally similar push pins 52, 52 extend from the ejector-plate and back-up plate through the ejector-half 14 to engage the front face of the coverhalf when the die halves are engaged. These push pins thereby thrust the ejector plate and back-up plate assembly relatively rearwardly with respect to the ejector-half to properly position the ends of the ejector pins 5t), 50 relative to the cavity.

When the die has been cast, and the ejector-half 14 is retracted with the platen 10, the anchor plate 30 and the base plates 32, 32, it carries the cast product and runner rearwardly with it. Near the end of the rearward travel of this assembly, stop pins 54, 54 engage a fixed I stop and prevent further rearward movement of the backup plate 46 and the ejector plate 44- to eject the casting from the ejector-half. More specifically, the stop pins 54, 54 at their front ends engage the rear surface of the back-up plate 46 and they have shoulders 56, 56 seated in suitable apertures in the anchor plate 30 so that they will carry the ejector plate and back-up plate forwardly with the anchor plate and the ejector-half of the die. The said stop pins also have rearwardly extending reduced diameter portions 58, 58 which slidably project through the anchor plate 30 and the movable platen 10 to engage a stop plate (not shown) as the ejector-half assembly is retracted. This thrusts the stop pins 54, 54 relatively forwardly and the ejector pins 50, 50 are thrust into the cavity area to eject the casting. All of the aforedescribed portion of the die construction is conventional.

As has been mentioned before, the improved die construction of this invention incorporates a high-frequency vibrator which is so constructed and arranged asto act upon the molten metal in the die cavity with the result that the improved final product is obtained. Preferably;

the vibrations produced in the molten metalare of ultrasonic frequency.

One type of device suitable for the purpose of producing the ultrasonic vibration desired is that known as the sonifier manufactured by Branson Instruments, Inc. of Stamford, Connecticut. This device comprises a power supply unit and a sonic converter or transducer. A description of the sonifier is published in the winter 1961- 1962 edition of Ultrasonic News, a copyrighted publication of Branson Instruments, Inc. The power supply unit is shown schematically and designated generally by the reference number 66 in FIG. 1, and it is an electronic instrument capable of converting a 50 or 60 cycle alternating current signal at 115 volts to radio frequency power at approximately 20,000 cycles per second. The power output at radio frequency is transmitted to the transducer which is preferably a device of piezoelectric material or a magnetostrictive material which converts the high-frequency electrical energy to mechanical vibratory energy at the same frequency. The preferred piezoelectric material is lead zirconate titanate which has the ability to deliver great amounts of mechanical energy at high efiiciency from a full wave electrical energy input. When a magnetostrictive material is used, nickel or nickel alloys are preferred. As shown in the drawings, the electrical signal from the power supply unit 60 is transmitted to the transducer which is indicated generally by the reference numeral 62- through a conductor 64.

As best shown in FIGS. 2, 3 and 4, the transducer 62 comprises a relatively large diameter body portion 66, the piezoelectric or magnetostrictive block 68 and a tapered or reduced diameter horn 70 on the said block which terminates in a tip 72. The transducer can be mounted on either the ejector-half or the cover-half of the die, but for convenience in installation and general access, .it is preferably mounted on the ejector-half 14. It will be noted with reference to FIG. 3 that the anchor plate 30, the back-up plate 46, the ejector plate 44, the ejector-half 14 and its cavity retainer block 42 are all provided with registering passages for the installation of the transducer and for access thereto. It will be noted further that the tip 72 of the transducer horn 70 is located in flush relationship with the surface of the cavity block 42 which cooperates to define the cavity 34. Preferably, the transducer is so located that its vibratory tip will engage the molten metal in the runner 36 closely adjacent the gate 40 to the product cavity 38.

The mounting of the transducer is by means of a nodal ring 74 which embraces the piezoelectric block 68 adjacent the horn 70 and which is secured in the ejector-half 14 by means of a plurality of screws such as the screw 76 which extend through the ejector-half and into the die cavity block 42. The nodal ring 74 is located on the transducer at its null point, i.e., the point at which no expansion or contraction of the material occurs as a result of the electrical signal which it receives. The said material does expand and contract on each side of the ring 74, the expansion and contraction on the horn side being concentrated due to the reduced diameter configuration of the horn so that the tip 72 will be vibrated over a relatively substantial distance which may be on the order of .005 inch. It is important to observe that the transducer is mounted solely by means of the ring 74 and that its other parts have freedom of movement Within the openings provided in the die elements with which they are associated. Thus, the vibration effected at the ultrasonic frequencies causes no noise due to mounting.

An alternative mounting arrangement for the transducer is shown in FIG. 4, and the alternative mount is sometimes preferred. In the said alternative form of mounting, a generally cylindrical member 80 is welded to a plate 82 to project forwardly therefrom and the said plate is secured to a slightly modified ejector plate 44a as by machine screws 84, 84. A front annular plate 86 is secured to the cylindrical member 80 and the nodal ring 88 is mounted thereon by rearwardly extending screws such as the screw 90.

In the aforedescribed alternative mounting for the transducer, it moves with the ejector plate and the ejector pins. When the die halves are closed, the vibrating tip 72 of the transducer is flush with the cavity surface as shown in full lines in FIG. 4, but when the die halves are opened to eject the casting, the tip 72 projects forwardly from the face of the ejector-half 14 as shown by the broken lines in FIG. 4. This has the advantage of ejecting any chips or spray that may be trapped between the wall of the die and the horn of the transducer and thereby wedging of the vibrating transducer is fully avoided.

The invention claimed is:

l. A die construction for a die casting machine and comprising a cover-half and an ejector-half which engage to define a cavity for casting a metal product and a runner attached thereto at a gate, the die casting machine being of the type which has means for mounting the said die halves for relative movement so that they can be selectively engaged or closed and then opened respectively to receive molten metal and to eject the formed product and its runner, one of the, said die halves being provided with an opening extending therethrough and communicating with the cavity, an electro-mechanical transducer disposed within said opening for movement therein and having a reduced end substantially flush with a surface of said one die half at the cavity, the said transducer being connectible with a source of radio frequency electrical energy and comprising a material capable of changing its dimension responsive to and in keeping with the frequency of such electrical energy to vibrate its reduced end, a nodal ring embracing said transducer between its ends at a point of minimum vibration, and means for mounting said ring within said opening to support the transducer therein.

2. A die construction as set forth in claim 1 and wherein the opening through the said one die half is arranged to communicate with the cavity in the runner portion thereof adjacent the gate.

3. A die construction for a die casting machine and comprising a cover-half and an ejector-half which engage to define a cavity for casting a metal product and a runner attached thereto at a gate, the die casting machine being of the type which has means for mounting the said die halves for relative movement so that they can be selectively engaged or closed and then opened respectively to receive molten metal and to eject the formed product and its runner, the said ejector-half being provided with an opening extending therethrough and communicating with the cavity, an electro-mechanical transducer disposed within said opening for movement therein and being of generally cylindrical configuration and having a reduced diameter end substantially flush with a surface of said ejector-half at the cavity, the said transducer comprising a piezoelectric material connectible with a source of radio frequency electrical energy and responsive thereto and in keeping with its frequency to change its dimension and thereby vibrate the reduced diameter end, a nodal ring embracing the transducer between its ends at a point of minimum vibration, and means for mounting said ring within the opening to support the transducer therein.

4. A die-construction for a die casting machine and comprising a cover-half and an ejector-half which engage to define a cavity for casting a metal product and a runner attached thereto at a gate, the die casting machine being of the type which has means for mounting the said die halves for relative movement so that they can be selectively engaged or closed and then opened respectively to receive molten metal and to eject the formed product and its runner, the said ejector-half comprising a subassembly which includes an ejector plate movable a limited distance relative to other parts of the ejector-half to eject a finished casting, and said other parts having an opening therethrough communicating with the cavity, an electro-meehanical transducer disposed Within said opening for movement therein, the said transducer being connectible with a source of radio frequency electrical energy and comprising a material capable of changing its dimension responsive to and in keeping with the frequency of such electrical energy whereby the transducer is vibrated, and means on said ejector plate supporting said transducer with one of its ends substantially flush with a surface of said ejector-half at the cavity when the die halves are closed and for projecting the said one end of the transducer into the cavity area when the die halves are open to eject a casting.

5. A die construction for a die casting machine and comprising a cover-half and an ejector-half which engage to define a cavity for casting a metal product and a runner attached thereto at a gate, the die casting machine being of the type which has means for mounting the said die halves for relative movement so that they can be selectively engaged or closed and then opened respectively to receive molten metal and to eject the formed product and its runner, the said ejector-half comprising a subassembly which includes an ejector plate movable a limited distance relative to other parts of the ejector-half to eject a finished casting, and said other parts having an opening therethrough communicating with the cavity, an

electro-mechanical transducer disposed within said opening for movement therein and being of generally cylindrical configuration and having a reduced diameter end, the said transducer comprising a piezoelectric material connectible with a source of radio frequency electrical energy and responsive thereto and in keeping with its frequency to change its dimension and thereby vibrate its reduced diameter end, and means on said ejector plate including a ring embracing said transducer to support it With its reduced diameter end substantially flush with a surface of the ejector-half at the cavity when the die halves are closed and for projecting the reduced diameter end into the cavity area when the die halves are open to eject a casting.

6. A die construction as set forth in claim 5 wherein the opening through the said ejector-half communicates with the cavity in the runner portion thereof adjacent the gate.

References ited by the Examiner Weber et al.: Sound Waves Improve Diecasting Quality, Foundry, February, 1961, pp. 69-71.

MICHAEL V. BRINDISI, Primary Examiner.

WILLIAM J. STEPHENSON, Examiner.

Claims (1)

1. A DIE CONSTRUCTION FOR A DIE CASTING MACHINE AND COMPRISING A COVER-HALF AND AN EJECTOR-HALF WHICH ENGAGE TO DEFINE A CAVITY FOR CASTING A METAL PRODUCT AND A RUNNER ATTACHED THERETO AT A GATE, THE DIE CASTING MACHINE BEING OF THE TYPE WHICH HAS MEANS FOR MOUNTING THE SAID DIE HALVES FOR RELATIVE MOVEMENT SO THAT THEY CAN BE SELECTIVELY ENGAGED OR CLOSED AND THEN OPENED RESPECTIVELY TO RECEIVE MOLTEN METAL AND TO EJECT THE FORMED PRODUCT AND ITS RUNNER, ONE OF THE SAID DIE HALVES BEING PROVIDED WITH AND OPENING EXTENDING THRETHROUGH AND COMMUNICATING WITH THE CAVITY, AND ELECTRO-MECHANICAL TRANSDUCER, DISPOSED WITHIN SAID OPENING FOR MOVEMENT THEREIN AND HAVING A REDUCED END SUBSTANTIALLY FLUSH WITH A SURFACE OF SAID ONE DIE HALF AT THE CAVITY, THE SAID TRANSDUCER BEING CONNECTIABLE WITH A SOURCE OF RADIO FREQUENCY ELECTRICAL ENERGY AND COMPRISING A MATERIAL CAPABLE OF CHANGING ITS DIMENSION RESPONSIVE TO AND IN KEEPING WITH THE FREQUENCY OF SUCH ELECTRICAL ENERGY TO VIBRATE ITS REDUCED END, A NODAL RING EMBRACING SAID TRANSDUCER BETWEEN ITS ENDS AT A POINT OF MINIMUM VIBRATION, AND MEANS FOR MOUNTING SAID RING WITHIN SAID OPENING TO SUPPORT THE TRANSDUCER THEREIN.

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