Method of repairing defects in cast iron workpieces, and a method of connecting cast iron workpieces

Patent metadata

Field	Value
Publication number	US-9545665-B2
Application number	US-201114365795-A
Country	US
Kind code	B2
Filing date	Dec 15, 2011
Priority date	Dec 15, 2011
Publication date	Jan 17, 2017
Grant date	Jan 17, 2017

Abstract

A method of repairing defect in cast iron workpiece, including: machining the workpiece in the area of the defect to remove the defective material and form a chamber opening at a surface of the workpiece; anchoring a receptacle to the workpiece above the chamber ( 2 ), the receptacle is provided with an orifice in communication with the chamber; adding molten iron ( 4 ) into the receptacle so that it at least part of it flows into the chamber; adding slagging agent ( 5 ) into the receptacle; heating the slagging agent and the molten iron with an electrode ( 6 ); adding nodulizing agent into the molten iron so as to segregate graphite; and allowing the molten iron and the workpiece to cool down slowly. The above-described technique also has applicability for connecting two cast iron workpieces ( 11,12 ) together.

First claim

The invention claimed is:

1. A method of repairing a defect in a ductile cast iron workpiece, comprising:
machining the workpiece in an area of the defect to remove the defect and form a chamber opening at a surface of the workpiece;
anchoring a receptacle to the workpiece above the chamber, wherein the receptacle is provided with an orifice in communication with the chamber;
adding molten iron into the receptacle so that at least part of the molten iron flows into the chamber;
adding a slagging agent into the receptacle;
heating the slagging agent and the molten iron with an electrode;
adding a nodulizing agent into the molten iron so as to segregate graphite; and
allowing the molten iron and the workpiece to cool down slowly.

2. The method according to claim 1 , wherein the step of allowing the molten iron and the workpiece to cool down slowly includes allowing the molten iron and the workpiece to cool through natural air cooling by exchanging heat with the ambient environment.

3. The method according to claim 1 , wherein the step of allowing the molten iron and the workpiece to cool down slowly includes allowing the molten iron and the workpiece to cool through natural air cooling and simultaneous application of a certain degree of heat.

4. The method according to claim 1 , wherein the step of adding the nodulizing agent into the molten iron includes inserting into the molten iron a feeder tube containing a wire therein.

5. The method according to claim 1 , wherein the nodulizing agent is magnesium or an alloy of magnesium and rare earth.

6. The method according to claim 1 , wherein the step of adding molten iron into the receptacle includes melting a consumable cast iron electrode.

7. The method according to claim 1 , wherein the molten iron is of the same chemical composition as that of the cast iron workpiece to be repaired.

8. The method according to claim 1 , further including detecting the defect through a non-destructive technique.

9. The method according to claim 1 , further including removing the receptacle and a redundant part from the workpiece after cooling down.

10. The method according to claim 1 , wherein the cast iron workpiece is formed from spheroidal graphite cast iron.

11. The method according to claim 1 , wherein the cast iron workpiece is a hub for a wind turbine.

12. A method of connecting two ductile cast iron workpieces together, comprising:
bringing together the two cast iron workpieces so that adjacent surfaces to be welded define a chamber therebetween and fixing the two cast iron workpieces at a desired position;
anchoring a receptacle to at least one of the two cast iron workpieces above the chamber, wherein the receptacle is provided with an orifice in communication with the chamber;
adding molten iron into the receptacle so that at least part of the molten iron flows into the chamber;
adding a slagging agent into the receptacle;
heating the slagging agent and the molten iron with an electrode;
adding a nodulizing agent into the molten iron so as to segregate graphite; and
allowing the molten iron and the two workpieces to cool down slowly.

13. The method according to claim 12 , wherein the step of allowing the molten iron and the two workpieces to cool down slowly includes allowing the molten iron and the two workpieces to cool through natural air cooling by exchanging heat with the ambient environment.

14. The method according to claim 12 , wherein the step of allowing the molten iron and the two workpieces to cool down slowly includes allowing the molten iron and the two workpieces to cool through natural air cooling and simultaneous application of a certain degree of heat.

15. The method according to claim 12 , wherein the step of adding the nodulizing agent into the molten iron includes inserting into the molten iron a feeder tube containing a wire therein.

16. The method according to claim 12 , wherein the nodulizing agent is magnesium or an alloy of magnesium and rare earth.

17. The method according to claim 12 , wherein the step of adding molten iron into the receptacle includes melting a consumable cast iron electrode.

18. The method according to claim 12 , wherein the molten iron is of the same chemical composition as that of the cast iron workpieces to be connected.

19. The method according to claim 12 , wherein at least one of the two cast iron workpieces is machined to define the chamber.

20. The method according to claim 12 , further including removing the receptacle and a redundant weld portion from the workpieces after cooling down.

21. The method according to claim 12 , wherein the two cast iron workpieces are parts of a hub for a wind turbine.

22. The method according to claim 12 , wherein the step of fixing the two cast iron workpieces at a desired position includes anchoring a bottom plate padded with a refractory layer to the two cast iron workpieces so as to close at least one side of a space between the two cast iron workpieces.

Assignees

• Zhang Hong Wei
• Vestas Wind Sys As

Inventors

• Zhang Hong Wei

Classifications

• B23K25/005

  Welding for purposes other than joining, e.g. build-up welding · CPC title

• B22D19/04

  for joining parts · CPC title

• B23P6/04

  Repairing fractures or cracked metal parts or products, e.g. castings · CPC title

• B22D23/06

  Melting-down metal, e.g. metal particles, in the mould · CPC title

• B22D23/10

  Electroslag casting {(electroslag remelting C22B9/18)} · CPC title