Molten metal pump

• US 5,088,893 A
• Filed: 01/25/1991
• Issued: 02/18/1992
• Est. Priority Date: 02/24/1989
• Status: Expired due to Fees

• Current Assignee: Metaullics Systems Company LP (Pyrotek Incorporated)
• Original Assignee: Carborundum Universal Investment Limited (Compagnie de Saint-Gobain SA)
• Inventors: Gilbert, Ronald E., Mordue, George S.
• Primary Examiner(s): KWON, JOHN
• Application Number:
  US07/649,221
• Time in Patent Office: 389 Days
• Field of Search: 415/200, 415/203, 415/206, 415/214.1, 248/225.31, 248/230, 248/231.7, 248/316.1
• US Class Current: 415/200
• CPC Class Codes: B22D 39/00 Equipment for supplying molten metal in rations
• CPC Class Codes: F04D 13/021 containing a coupling
• CPC Class Codes: F04D 29/047 hydrostatic; hydrodynamic
• CPC Class Codes: F04D 7/065 for liquid metal

Abstract

A molten metal pump includes an impeller disposed at the end of an elongate drive shaft. The drive shaft is disposed within an elongate, hollow post. The impeller and the end of the post are adapted to be immersed in molten metal. An inert gas is conveyed through the gap between the outer surface of the drive shaft and the inner surface of the post, which gas is discharged into the molten metal in the vicinity of the impeller. Because the drive shaft is insulated from the molten metal, it can be made of a durable material such as steel; because the post is stationary relative to the molten metal, the metal is stirred only by the impeller, and not by the drive shaft. The invention includes other features such as a quick disconnect capability and a radial adjustment capability.

Claims

1. A molten metal pump, comprising:

an elongate, hollow, refractory post having first and second ends, the first end adapted to extend out of the molten metal and the second end adapted to extend into the molten metal;

an elongate drive shaft disposed within the post for rotation therein, the drive shaft having first and second ends, the first end adapted to extend out of the first end of the post and the second and adapted to be disposed adjacent the second end of the post;

an impeller connected to the second end of the drive shaft;

a stator connected to the second end of the post, the stator including a cavity within which the impeller is disposed, an inlet into which molten metal can be drawn, an outlet through which molten metal can be discharged, and an opening through which gas can be discharged into the molten metal, the impeller being spaced from the stator; and

means for conveying gas between the outer surface of the drive shaft and the inner surface of the post, through the space between the impeller and the stator, and through the opening in the stator.

2. The molten metal pump of claim 1, wherein the smallest gap between the impeller and the stator is approximately 0.015 inch.

3. The molten metal pump of claim 1, further comprising a bearing member lining a portion of the cavity in the stator, and a bearing member surrounding a portion of the impeller, the bearing members being disposed adjacent each other for sliding contact during use.

4. The molten metal pump of claim 3, wherein the bearing members are made of a refractory material such as silicon carbide.

5. The molten metal pump of claim 1, further comprising a support member to which the first end of the post is secured, the post being radially adjustable relative to the support member.

6. The molten metal pump of claim 5, further comprising a cylindrical extension projecting from the first end of the post, and a U-bolt passing about the cylindrical extension, the U-bolt being releasable connected to the support member.

7. The molten metal pump of claim 5, further comprising a hollow extension projecting from the first end of the post, a drive motor connected to the hollow extension, and a releasable connection between the drive motor and the first end of the drive shaft.

8. The molten metal pump of claim 6, wherein the drive motor is connected to the drive shaft by means of a splined connection.

9. The molten metal pump of claim 1, further comprising a hollow extension projecting from the first end of the post, a bearing disposed within the extension, the bearing being axially fixed relative to the extension, the bearing having an opening through which the first end of the drive shaft projects, the bearing supporting the first end of the drive shaft for rotation.

10. The molten metal pump of claim 9, further comprising a first collar disposed about the drive shaft on the side of the bearing opposite the impeller, the first collar being adjustably connected to the drive shaft such that the axial position of the drive shaft relative to the post can be adjusted.

11. The molten metal pump of claim 10, further comprising a second collar disposed about the drive shaft on the side of the first collar opposite the impeller, the second collar being rigidly secured to the drive shaft such that removal of the drive shaft from the post can be prevented upon loosening the first collar.

12. The molten metal pump of claim 9, further comprising an opening in the side of the hollow extension, the opening being in fluid communication with the space between the drive shaft and the post.

13. The molten metal pump of claim 1, further comprising a hollow fitting connected to the outlet of the stator, and a riser tube connected to the fitting, the riser tube having a first end disposed outside the molten metal and a second end connected to the outlet of the fitting.

14. The molten metal pump of claim 13, wherein the riser tube is of the same size and shape as the post.

15. The molten metal pump of claim 13, further comprising a hollow extension projecting from the first end of the riser tube, and a support member to which the hollow extension is connected.

16. The molten metal pump of claim 15, further comprising a U-bolt passing about the hollow extension, the U-bolt being releasably connected to the support.

17. The molten metal pump of claim 15, further comprising a flange loosely disposed about the hollow extension, the flange being radially adjustable relative to the hollow extension.

18. The molten metal pump of claim 1, further comprising insulation disposed about the outer surface of the post.

19. The molten metal pump of claim 18, wherein the insulation is in the form of intumescent paper in contact with the post and a refractory coating disposed about the intumescent paper.

20. The molten metal pump of claim 1, wherein the drive shaft is made of steel.

21. A method of protecting a drive shaft used in a molten metal pump, comprising the steps of:

providing an elongate, hollow, refractory post having first and second ends;

providing an elongate drive shaft having first and second ends;

providing an impeller and attaching the impeller to the second end of the drive shaft;

providing a stator and connecting the stator to the second end of the post, the stator including a cavity, an inlet into which molten metal can be drawn, an outlet through which molten metal can be discharged, and an opening through which gas can be discharged into the molten metal;

placing the drive shaft within the refractory post such that the first end of the drive shaft is adjacent the first end of the post and the impeller is adjacent the second end of the post, the impeller being disposed within the cavity and spaced from the stator;

placing the second end of the post and the impeller in molten metal while keeping the first end of the post and the first end of the drive shaft out of the molten metal;

rotating the drive shaft while preventing the post from rotating; and

conveying gas between the post and the drive shaft, through the space between the impeller and the stator, and through the opening in the stator for discharge into the molten metal.

22. The method of claim 21, wherein the smallest gap between the impeller and the stator is approximately 0.015 inch.

23. The method of claim 21, wherein the drive shaft is made of steel.