US20090218375A1

US20090218375A1 - Close proximity pouring device

Info

Publication number: US20090218375A1
Application number: US12/074,285
Authority: US
Inventors: Doyle Ray Ledbetter
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-03-03
Filing date: 2008-03-03
Publication date: 2009-09-03

Abstract

There is disclosed herein a Close Proximity Pouring Device to automatically pour molten metal into a mold. The pouring device consists of a pour box equipped with a stopper rod and nozzle to dispense molten metal into a mold. This is accomplished by lowering the pour box so that a truncated conical pour nozzle, which extends below the pour box, is lowered into a truncated conical cavity in the mold without making contact with the mold. Then, when the stopper rod is opened, molten metal flows from the pour box through the nozzle and into the mold. As the molten metal fills the conical void between the nozzle and the mold, a seal is established preventing air from entering the mold. Oxidation and/or gassing of the molten metal entering the mold is minimized reducing the chance of producing defective castings. Once the molten metal seal is achieved between the nozzle and the mold, the metal head in the pouring vessel adds head pressure to improve filling the mold. Likewise, as the molten metal flows through the nozzle and fills the conical void between the nozzle and the mold, energy is transferred from the molten metal to the tip of the nozzle. By heating the tip of the nozzle during each pour, buildup of metal and metal oxides on the nozzle is eliminated.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

Not Applicable

FEDERALLY SPONSORED RESEARCH

Not Applicable

SEQUENCE LISTING OR PROGRAM

Not Applicable

BACKGROUND OF THE INVENTION

1. Technical Field of Invention
This invention relates generally to an unheated pour box for pouring molten metal into a mold and, more particularly, to such a device equipped with a means to heat the tip of the nozzle during each pour thereby keeping a building up from forming in the nozzle.
2. Discussion of Related Art
Historically, the pouring of molten metals into molds was done by hand. Because hand pours were not consistent, stopper rod pouring became the preferred method. Herein, molten metal is metered from a pour box and into a mold using a stopper rod and a nozzle. As the stopper rod is raised from it down or closed position, the metal flow rate increases from no flow to its maximum flow rate which is controlled by the height of the metal in the pour box and the diameter of the opening in the nozzle.
When stopper rod pouring, the fill rate of a mold is faster at the beginning of the pour than at the end of the pour since the head pressure of the molten metal in the mold decreases as the mold cavity fills. Consequently, the stopper rod must be modulated to slow down the pour rate to prevent over filling a mold. As the stopper rod closes, the last metal to flow from the nozzle tends to freeze, buildup and progressively close down the orifice in the nozzle resulting in erratic pours.
Because the pour box is located above the mold, molten metal flows through air before entering the sprue cup in the mold. Not only does this results in oxidation of some of the metal, but air is aspirated into the sprue gassing some metals.
Contact pouring was developed by Brunner U.S. Pat. No. 5,465,777 to address the aforementioned problems. Herein, a pressure pour furnace was lowered so that a flat bottom nozzle located in the pour launder would contact a flat surface on the mold. Once the seal was made between the nozzle and mold, the stopper rod was raised and metal flowed into the mold.
Contact pouring was also developed by Billau U.S. Pat. No. 6,138,742, wherein molten metal is poured through the orifice of a nozzle that was flush with the bottom of the vessel and the mold.
The advantages reported for contact pouring were as follows. First, when the nozzle is seated flush to the mold, air is prevented from entering the mold via the sprue. Second, a significant improvement in the mold fill rate is achieved because the metal head in the pour box provided additional pressure to aid in filling the last portion of the mold. Third, there is no need to modulate the stopper rod opening from beginning to end of pour. Fourth, there is an increase in the casting yield because the weight of the metal associated with the sprue cup was eliminated. Fifth, there is no overfilling of a mold which leaves metal atop the mold.

DISADVANTAGES OF THE PRIOR ART

The problem with contact pouring is that the nozzle is cooled each time it contacts a mold. Consequently, metal builds up on the nozzle which progressively alters the subsequent pours. To remove the buildup, Brunner U.S. Pat. No. 5,465,777 used a milling cutter to face the bottom of the nozzle. However, the milling cutter could not remove the buildup with the nozzle orifice. Furthermore, the production rate dropped off because the time to face of the nozzle increased the cycle time per mold.

OBJECTS AND ADVANTAGES

It is an objective of the present invention to overcome the disadvantages of the prior art by providing an improved means to stopper rod pour molten metals into molds while externally heating the nozzle to minimize buildup on the nozzle.

DRAWINGS Figures

Still other objectives of the present invention will become apparent to those skilled in the art after reading the following specification and by referencing the drawings which:

FIG. 1 is a cross section of the Close Proximity Pouring Device in the up position.

FIG. 2 is a cross section of the Close Proximity Pouring Device in the down position.

FIG. 3 is a cross section of the Close Proximity Pouring Device in the down position pouring a mold.

FIG. 4 is a cross section of the Close Proximity Pouring Device in the up position just after pouring a mold.

REFERENCE NUMERALS

Referring to the drawings, in all of which, like parts are designated by like reference characters.
FIG. 1. typical close proximity pouring device

- 110 pour box
- 111 mold
- 112 linear actuator
- 113 stopper rod actuator
- 114 stopper rod
- 115 molten metal
- 116 nozzle
- 117 truncated conical shape
- 118 truncated conical pour basin

FIG. 2. typical close proximity pouring device cross section in the down position

- 210 fixed stops

FIG. 3. typical close proximity pouring device cross section in the down position with the stopper rod actual raised.

- 310 sprue
- 311 mold cavity

FIG. 4. typical close proximity pouring device cross section in the up position

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following description of the preferred embodiment is merely exemplary in nature and is not intended to limit the invention, its application or uses.
In FIG. 1 there is shown a cross section of a close proximity pouring device 100 in the up position. A pour box 110 is held above the mold 111 by means of mechanical devices such as a hydraulic cylinder, a cam or a linear actuator 112. The pour box 110 is fitted with a stopper rod actuator 113 which raises and lowers a stopper rod 114. The stopper rod 114 keeps the molten metal 115 in the pour box 110 by means of contact with the nozzle 116. The bottom of the nozzle 116 has a truncated conical shape 117. Likewise, the mold 111 has truncated conical shaped pour basin 118.
In FIG. 2 there is shown a cross section of a close proximity pouring device 100 in the down position. Herein, the pour box 110 has been lowered relative to the mold 111 by means of mechanical devices such as a hydraulic cylinder, a cam or a linear actuators 112 until the pour box 110 sets atop fixed stops 210 so that there is no contact between the nozzle 116 and the mold 111.
In FIG. 3 there is shown a cross section of a close proximity pouring device 100 in the down position wherein the stopper rod actuator 113 has raised the stopper rod 114 to allow molten metal 115 to flow from the pour box 110 and into the mold 111. As the molten metal 115 flows into the mold 111, the down sprue 310 fills with molten metal 115. Since the rate of metal flow into the sprue 310 is faster than the rate at which the mold cavity 311 will accept the molten metal 115, the molten metal 115 fills part of the conical gap 117 between the truncated conical shape 117 of the nozzle 116 and the truncated conical pour basis 118 in the mold 111. The hot metal 115 heats the nozzle 116 during each pour. After three or four pours, the nozzle 116 becomes heated so that the molten metal 115 does not stick to and build up on the nozzle 116.
In FIG. 4 there is shown a cross section of a close proximity pouring device 100 in the up position just after a pour wherein the stopper rod actuator 113 has closed the stopper rod 114 to stop molten metal 115 flow from the pour box 110 and into the mold 111. The molten metal 115 that was in the orifice in the nozzle 116 flowed into the truncated conical pour basin 118. The result is that there are no short or long pours.

CONCLUSION

The foregoing discussions, disclosures and describes are merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.

Claims

1. A method of pouring molten metals comprising:

a pour box to hold molten metal;

a stopper rod actuator to allow metal to flow from a pour box;

a means to raise and lower the pour box;

a truncated conical nozzle through which the metal flows;

a truncated conical cavity in the mold; and

a gap between the truncated nozzle and the truncated cavity in the mold.

2. A method of pouring molten metal as in claim 1 where in molten metal fills part of the conical opening between the nozzle and the mold so that the tip of the nozzle is heated during each pour.

3. A method of pouring molten metal as in claim 1 where in the gap between the truncated conical nozzle and the truncated conical cavity in the mold is sized so that the surface tension of the metal will allow only a portion of the gap between the nozzle and the mold to fill without overflowing metal atop the mold.

4. A method of pouring molten metal as in claim 1 where in the molten metal forms a seal between the nozzle and the mold preventing aspiration of air into the mold.

5. A method of pouring molten metal as in claim 1 where once the a molten metal seal is achieved between the nozzle and the mold, the metal head in the pouring vessel adds head pressure to improve filling the mold.

6. A method of pouring molten metal as in claim 1 where in the pour box is raised and lowered by means of mechanical devices such as a hydraulic cylinder, a cam or a linear actuator operated device

7. A method of pouring molten metal as in claim 1 where in the pour box sits atop positioning devices to provide precise vertical control of the nozzle placement in the mold without contacting the mold when in the down position.