WO2001019553A1

WO2001019553A1 - A flow control assembly

Info

Publication number: WO2001019553A1
Application number: PCT/EP2000/009253
Authority: WO
Inventors: David Rees; Peter Charles Dann
Original assignee: Aluminium Pechiney; Pechiney Rhenalu
Priority date: 1999-09-14
Filing date: 2000-09-14
Publication date: 2001-03-22
Also published as: AUPQ284599A0

Abstract

A flow control assembly for a metallurgical plant. The assembly includes a passage defining means or spout (10) and a control means or plug (26). The spout (10) has an inlet opening (16) at one end and an outlet opening (18) at the other end. The plug (26) is receivable in a passage (14) defined by the spout (10). The plug (26) has a first cooperating formation (34) which cooperates with the inlet opening (16) of the spout (10) and a second cooperating formation (36) which cooperates with the outlet opening (18) of the spout (10).

Description

A FLOW CONTROL ASSEMBLY

Field of the Invention

This invention relates to a flow control assembly.

The invention has been developed primarily for use in metallurgical plants, such as aluminium smelters, and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use.

Background of the Invention

Metals, in a molten state, are moved between various receptacles in a casting process. It is necessary to control the flow of the molten metal as it is moved between receptacles. Various devices are known for controlling the flow of the metal, including those known as plug and spout devices.

In one type of plug and spout device, an inlet to the spout is closed by the plug for blocking the supply of the metal to a receptacle arranged downstream of the device. With this device, a low pressure develops at the inlet to the spout, when open, which can cause induction of air into the spout during the casting operation. This results in a large number of impurities occurring in the cast metal which is unsatisfactory.

In another type of plug and spout device, flow through an outlet to the spout is controlled by the plug. If, for some reason, a casting process is aborted, the plug closes off the outlet of the spout to stop the process. Molten metal residing in the spout, at the time the outlet is closed, solidifies in the spout. This necessitates replacement of the plug and spout device at great cost.

Object of the Invention It is an object of the invention to substantially overcome or at least ameliorate the above disadvantages.

Summary of the Invention

According to the invention, there is provided a flow control assembly for a metallurgical plant, the assembly including: a passage defining means having an inlet opening at one end and an outlet opening at an opposed end; and a control means receivable in a passage defined by the passage defining mean, the control mean defining a first cooperating formation which cooperates with the inlet opening of the passage defining mean and a second cooperating formation which cooperates with the outlet opening of the passage defining means. The passage defining means and the control means, respectively, are referred to in the art as a spout and plug and shall be referred to as such below.

Preferably, in use, the spout is arranged in a vertical orientation with the inlet opening above the outlet opening such that molten metal, in particular aluminium, flows through the spout under gravity from a first receptacle such as a launder into a second receptacle such as a casting mould, a casting ladle, another launder, or the like.

In one form, the spout has a bell-shaped appearance such that the outlet opening has a smaller diameter than the inlet opening.

A part of the wall of the spout preferably defines the outlet opening. The part of the wall in proximity to the outlet opening is preferably shaped to inhibit turbulent flow of the metal through the outlet opening. In a preferred form, the part of the wall of the spout is substantially S-shaped.

The inlet opening preferably includes a seat-defining portion to define a seat. The seat-defining portion is desirably formed by a taper in an inner wall of the spout at the inlet opening. The plug preferably includes a rod shaped member. The first cooperating formation is desirably defined at, or in proximity to, a first end of the rod-shaped member with the second cooperating formation being defined at a second, opposed end of the rod-shaped member.

The first cooperating formation is preferably in the form of an outwardly flared wall portion arranged at a transition between the rod shaped member and a control plunger from which the rod shaped member extends. The taper of the wall portion desirably corresponds to the taper at the inlet opening of the spout such that, when the wall portion seats in the seat at the inlet opening, the flow of material through the passage of the spout is inhibited. The second cooperating formation is preferably substantially dome shaped. The length of the rod-shaped member is preferably such that, when the wall portion seats in the seat of the spout, the second cooperating formation does not fully close off the outlet opening thereby allowing drainage of material from the passage of the spout. When the inlet opening of the spout is open, the second cooperating formation serves as a throttling member and controls the discharge of molten through the outlet opening of the spout. Brief Description of the Drawings

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a schematic, sectional side view of a part of an embodiment of a flow control assembly according to the invention;

Fig. 2 is an enlarged, schematic, side view of a further part of the assembly shown in Fig. 1 ; and

Fig. 3 is a graph of flow control characteristics of the assembly shown in Figs. 1 and 2.

Detailed Description of the Preferred Embodiments

Fig. 1 shows an embodiment of a passage defining means or spout forming a first part of a flow control assembly according to the invention, which is designated generally by the reference numeral 10. The spout 10 has a cylindrical wall 12 which defines a passage 14. An inlet opening 16 is defined at a first end of the passage and an outlet opening 18 is defined at an opposed, second end of the passage 14.

The wall 12 of the spout 10 is substantially bell-shaped to define a shaped outlet opening which encourages laminar flow of molten metal, more particularly, aluminium, through the outlet opening 18. Thus, a part 12.1 of the wall 12 is substantially S-shaped to define the shape of the outlet opening 18. The shape of the part 12.1 of the wall 12 also means that the diameter of the outlet opening 18 is smaller than that of the inlet opening 16.

The inlet opening 16 includes a seat defining portion 20. The portion 20 is formed by a flared region of an inner surface 22 of the wall 12 and defines a seat 24 in which a first cooperating formation of a control means or plug 26 (see Fig. 2) seats, as will be described in greater detail below.

Fig. 2 shows the plug 26 in greater detail. The plug 26 includes a rod shaped member or rod 28 which is receivable in the passage 14 of the spout 10. The rod 28 depends from a control plunger 30 and is connected to the control plunger 30 via a transition region 32. The transition region 32 has an outwardly flared or tapered portion 34 which is wider at the control plunger end 30. The profile of the portion 34 corresponds to the taper of the seat 24 of the spout 10 so that the portion 34 seats in the seat 24 to close off flow of molten metal through the passage 14 of the spout 10. A second cooperating formation 36 is arranged at a free end of the rod 28. The formation 36 is substantially dome shaped and cooperates with the outlet opening 18 of the spout 10.

The length of the rod 28 and its formations 34 and 36 are such that, when the portion 34 seats in the seat 24 of the spout 10, the formation 36 remains clear of the outlet opening 18 such that an annular opening is created between the formation 36 and the inner surface 22 of the part 12.1 of the wall 12 of the spout 10. Thus, when the inlet opening 16 of the spout 10 is closed off by the portion 34 of the plug 26, molten metal in the passage 14 drains through the outlet opening 18 and solidification of the metal in the passage 14 is inhibited.

Fig. 3 shows a graph of the control characteristic of the flow control assembly (comprising the spout 10 and the plug 26).

The characteristic of the inlet opening 16 is such that, when the portion 34 is raised off the seat 24 at the inlet opening 16, flow through the inlet opening 16 is much more rapid than through the outlet opening 18. Hence, in use, when the spout 10 is opened by raising the portion 34 of the plug 26 off the seat 24, the passage 14 fills with molten metal. Thereafter, flow control shifts to the bottom or outlet opening 18 of the spout 10 as illustrated at 38 in Fig. 3 of the drawings. The profile of the portion 34 inhibits turbulence at the transition from the plunger 30 to the rod 28. The shape of the internal surface of the part 12.1 of the wall 12 of the spout 10 and the shape of the formation 36 of the plug 26 inhibit turbulent flow through the outlet opening 18 to reduce the amount of impurities formed in the molten metal in a receptacle (not shown) arranged downstream of the spout 10.

It is a further advantage of the invention that, because flow of molten metal through the spout 10 is controlled by the inlet opening 16, when the inlet opening 16 closes, material in the passage 14 of the spout 10 can drain through the outlet opening 18. In so doing, solidification of the molten metal in the passage 14 is inhibited.

In addition, due to the different flow characteristics between the inlet opening 16 and the outlet opening 18, the effects of the creation of a low pressure region in annulus defined between the rod 28 and the taper 20 of the inlet opening 16 are minimised due to the effect that, initially, the passage 14 fills with metal before flowing out through the outlet opening 18. Because the molten metal flows through the outlet opening 18 at a reduced rate, the creation of a low pressure region at the outlet opening 18 is reduced thereby reducing the formation of eddies. Those skilled in the art will appreciate that the eddies are responsible for the formation of impurities in the cast metal. Thus, it is an advantage of the invention that a flow control assembly is provided which has a lower occurrence of impurities provided by a "bottom control" spout but which does not suffer from the disadvantage of solidification of molten metal in such a "bottom control" spout.

Although the invention has been described with reference to a preferred embodiment, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims

Claims:

1. A flow control assembly for a metallurgical plant, the assembly including: a passage defining means having an inlet opening at one end and an outlet opening at an opposed end; and a control means receivable in a passage defined by the passage defining mean, the control means defining a first cooperating formation which cooperates with the inlet opening of the passage defining mean and a second cooperating formation which cooperates with the outlet opening of the passage defining means.

2. The assembly as claimed in claim 1 , wherein the passage defining means is in the form of a spout and the control means is in the form of a plug.

3. The assembly as claimed in claim 2, wherein the spout is arranged in a vertical orientation with the inlet opening above the outlet opening such that molten metal flows through the spout under gravity from a first receptacle into a second receptacle.

4. The assembly as claimed in claims 2 or 3, wherein the spout has a bell- shaped appearance such that the outlet opening has a smaller diameter than the inlet opening.

5. The assembly as claimed in any one of claims 2 to 4, wherein a part of the wall of the spout defining the outlet opening and the part of the wall in proximity to the outlet opening is shaped to inhibit turbulent flow of the metal through the outlet opening.

6. The assembly as claimed in claim 5, wherein the part of the wall is substantially S-shaped.

7. The assembly as claimed in any one of claims 1 to 6, wherein the inlet opening includes a seat-defining portion to define a seat.

8. The assembly as claimed in claim 7, wherein the seat-defining portion is formed by a taper in an inner wall of the spout at the inlet opening.

9. The assembly as claimed in any one of claims 2 to 8, wherein the plug includes a rod shaped member.

10. The assembly as claimed in claim 9, wherein the first cooperating formation is defined at, or in proximity to, a first end of the rod-shaped member and the second cooperating formation is defined at a second, opposed end of the rod-shaped member.

11. The assembly as claimed in claims 9 or 10, wherein the first cooperating formation is in the form of an outwardly flared wall portion arranged at a transition between the rod shaped member and a control plunger which the rod shaped member extends.

12. The assembly as claimed in any one of claims 9 to 11, wherein the taper of the wall portion corresponds to the taper at the inlet opening of the spout such that, when the wall portion seats in the seat at the inlet opening, the flow of material through the passage of the spout if inhibited.

13. The assembly as claimed in claims 9 or 12, wherein the second cooperating formation is substantially dome shaped.

14. The assembly as claimed in any one of claims 9 to 13, wherein the length of the rod-shaped member is such that, when the wall portion seats in the seat of the spout, the second cooperating formation does not fully close off the outlet opening thereby allowing drainage of material from the passage of the spout.

15. The assembly as claimed in any one of claims 2 to 14, wherein, when the inlet opening of the spout is open, the second cooperating formation serves as a throttling member and controls the discharge of molten through the outlet opening of the spout.