Exothermic welding and method

• US 4,885,452 A
• Filed: 04/04/1988
• Issued: 12/05/1989
• Est. Priority Date: 04/04/1988
• Status: Expired due to Term

• Current Assignee: ERICO International Corporation (nVent Electric Plc)
• Original Assignee: ERICO International Corporation (nVent Electric Plc)
• Inventors: Kub, George F. Jr., Kovarik, David P., Amos, Michael D.
• Primary Examiner(s): Shaw, Clifford C.
• Application Number:
  US07/177,076
• Time in Patent Office: 610 Days
• Field of Search: 219/130.4, 228/241, 266/227, 361/251, 361/253, 361/256, 102/202.8, 206/568
• US Class Current: 219/130.4
• CPC Class Codes: B23K 23/00 Alumino-thermic welding

Abstract

Exothermic reaction mixtures are economically ignited remotely and electrically without the use of a low ignition starting material by creating a predetermined spark gap within a matrix of such mixture and then impressing a high energy spark across the gap through the use of a capacitor discharge circuit. The mixture is contained in a graphite or ceramic vessel or crucible and is supported over a tap hole or runner by a fusible metal disk. The material of the vessel is preferably graphite which is electrically conductive. In one form of the invention, an insulated wire with a bare tip is positioned just below the top surface of the mixture and the tip spaced a predetermined distance from the wall of the vessel. The capacitor discharge circuit is then employed to fire a high energy spark through a matrix of the material across the gap formed between the wire and vessel to initiate the reaction. In another form the spark gap may be established in a small cylindrical cartridge containing the material. The cartridge may be positioned through a hole in the side wall of the mold just below or near the top of the exothermic material so that it can be filled with the material from the main body of the exothermic material.

Claims

1. A method of welding at least one part with exothermic material comprising the steps of forming a spark gap in a matrix of such material, then creating a high energy spark across such gap sufficient to initiate and sustain an exothermic reaction of such material until such material is converted to molten metal, and directing such molten metal to a location surrounding said part to be welded.

2. A method as set forth in claim 1 wherein such high energy spark is created by a capacitor discharge electrical circuit.

3. A method as set forth in claim 2 wherein such capacitor discharge electrical circuit is battery operated and portable.

4. A method as set forth in claim 3 wherein such circuit includes a DC to AC inverter, a step up transformer and an AC to DC rectifier.

5. A method as set forth in claim 1 wherein such exothermic material is contained in a conductive crucible, said crucible being one electrode of such spark gap.

6. A method of converting exothermic material to molten metal comprising the steps of forming a spark gap in a matrix of such material, and then creating a high energy spark across such gap sufficient to initiate and sustain an exothermic reaction of such material wherein such matrix of exothermic material is contained in a small ignition cartridge and is expelled from such cartridge when ignited in turn to ignite a larger body of exothermic material.

7. A method as set forth in claim 6 wherein such cartridge is aimed to spray ignited exothermic material over the top surface of such larger body.

8. A method as set forth in claim 7 wherein such cartridge is aimed at a cover over such larger body to reflect over the top surface of such larger body.

9. A method as set forth in claim 6 wherein such cartridge is positioned just below the top surface of such larger body and is aimed upwardly.

10. A method as set forth in claim 9 wherein such cartridge is positioned in a side wall of a crucible for such larger body of exothermic material and is aimed at an angle toward the center of a cover for such crucible.

11. A method as set forth in claim 10 wherein said crucible is conductive and forms one electrode of such spark gap.

12. A method as set forth in claim 10 wherein such cover comprises a filter assembly.

13. A method as set forth in claim 6 wherein such small ignition cartridge comprises a housing containing the exothermic material, such housing being conductive and forming one electrode of such spark gap.

14. A method as set forth in claim 13 wherein a wire in the center of the housing forms the other electrode of such spark gap.

15. A method as set forth in claim 14 wherein such wire extends through an insulator at one end of such housing, the other end of such housing being closed by a frangible cap to contain such small amount of exothermic material.

16. A method as set forth in claim 6 wherein such small ignition cartridge comprises a cylindrical housing containing the exothermic material which is closed at one end and covered with a frangible cap at the other end.

17. A method as set forth in claim 16 wherein spaced wires extend through the wall of the housing to form the spark gap.

18. A method as set forth in claim 17 wherein such housing is formed of wood.

19. A method as set forth in claim 6 wherein such larger body of exothermic material is contained in a crucible, such ignition cartridge being mounted in a cover for such crucible and being aimed at the top surface of such larger body.

20. A method as set forth in claim 6 wherein the exothermic material in such small ignition cartridge is physically separated from such larger body.

21. A method as set forth in claim 6 wherein the exothermic material in such small ignition cartridge is contiguous with such larger body.

22. A method as set forth in claim 6 wherein such small ignition cartridge contains a gas generating material which causes the exothermic material contained therein to be expelled and sprayed therefrom upon ignition.

23. A method as set forth in claim 22 wherein such gas generating material is an organic material.

24. A method as set forth in claim 23 wherein such organic material is selected from the group consisting of acrylic paint, epoxy paint, latex paint, oil base paint and organic base glue.

25. A method as set forth in claim 22 wherein such gas generating material is a hydrate or aqueous material and such gas is vapor.

26. A method as set forth in claim 22 wherein the gas generating material is incorporated in a housing for the ignition cartridge.

27. The combination set forth in claim 26 wherein said high energy spark is generated by a capacitor discharge electrical circuit.

28. The combination set forth in claim 27 wherein said capacitor discharge electrical circuit is battery operated and hand portable.

29. The combination set forth in claim 28 wherein said circuit includes a DC to AC inverter, a step up transformer, and an AC to DC rectifier to charge the capacitor.

30. The combination set forth in claim 26 wherein said crucible or cover is conductive and forms one electrode of said spark gap.

31. The combination set forth in claim 30 wherein the other electrode is formed by a wire having a non-insulated tip spaced a predetermined distance from said crucible or cover.

32. The combination set forth in claim 31 wherein said wire is insulated and is bent at its end to space its tip such predetermined distance from the wall of the crucible.

33. The combination set forth in claim 31 wherein said wire extends through an insulating sleeve in a cylindrical hole in a side wall of said crucible with the tip projecting inwardly of the insulator and spaced by the insulator a predetermined distance from the wall of the crucible.

34. The combination set forth in claim 33 wherein said insulator is both an electric and refractory insulator.

35. The combination set forth in claim 34 wherein said insulator is a circular cylindrical sleeve of glass.

36. In combination a crucible and cover containing an exothermic reaction material mixture, ignition device means positioned in the crucible-cover combination including a spark gap, and exothermic reaction mixture material within the gap, and means to impress a high voltage across the gap to create a sufficiently high energy spark to ignite such exothermic reaction material in turn to ignite the exothermic reaction mixture in the crucible.

37. The combination set forth in claim 36 wherein said ignition means is positioned in the wall of the crucible just below the level of the exothermic reaction material.

38. The combination set forth in claim 36 wherein said ignition device means includes means to spray ignited exothermic material over the top surface of said material.

39. The combination set forth in claim 36 wherein said ignition device means contains a small body of exothermic reaction mixture adapted to be sprayed over the top surface of a main body of such material upon ignition.

40. The combination set forth in claim 39 wherein said small body is contiguous with said main body.

41. The combination set forth in claim 39 wherein said small body is separated from said main body.

42. The combination set forth in claim 39 wherein said ignition device means includes means to spray ignited exothermic material when such high energy spark is created.

43. The combination set forth in claim 42 wherein said last mentioned means comprises a small amount of gas generating material at the spark gap.

44. The combination set forth in claim 43 wherein said gas generating material is organic and is selected from the group consisting of acrylic paint, epoxy paint, latex paint, oil base paint and organic base glue.

45. The combination set forth in claim 43 wherein said gas generating material is a hydrate or aqueous material and such gas is vapor.

46. The combination set forth in claim 43 including a housing for said ignition device means, said gas generating material being incorporated in said housing.

47. An igniter for exothermic material comprising a housing containing exothermic material which is closed at one end and has a frangible cap at the other end, and a spark gap within said housing within said exothermic material, whereby when a high energy spark is created at such spark gap the exothermic material is ignited.

48. An igniter as set forth in claim 47 including means in said housing to expel ignited exothermic material through said frangible cap shortly after such high energy spark is created.

49. An igniter as set forth in claim 48 wherein said last mentioned means comprises a small amount of a gas generating material at such spark gap.

50. An igniter as set forth in claim 49 wherein said gas generating material is organic.

51. An igniter as set forth in claim 50 wherein said organic material is selected from the group consisting of acrylic paint, epoxy paint, latex paint, oil base paint and organic base glue.

52. An igniter as set forth in claim 49 wherein said gas generating material is a hydrate or aqueous material and such gas is vapor.

53. An igniter as set forth in claim 49 wherein said gas generating material is incorporated in said housing.

54. An igniter as set forth in claim 47 wherein said housing is cylindrical and conductive and forms one electrode of such spark gap.

55. An igniter as set forth in claim 54 wherein said housing is closed at one end by an insulator with a wire extending coaxially therethrough.

56. An igniter as set forth in claim 47 including a capacitor discharge circuit for generating such high energy spark.

57. An igniter as set forth in claim 56 wherein said circuit is battery operated and hand portable.

58. An igniter set forth in claim 57 wherein said circuit includes a DC to AC inverter, a step up transformer and an AC to DC rectifier to charge the capacitor.

59. A method of igniting an exothermic reaction mixture contained in a crucible comprising the steps of creating a high energy spark within a matrix of a small amount of such reaction mixture, such that when such small amount of reaction mixture ignites it is caused to spray molten reaction products onto the exothermic reaction mixture contained in the crucible thereby igniting the same.

60. A method of igniting an exothermic reaction mixture contained in a crucible comprising the steps of forming a spark gap within such reaction mixture, and then impressing a high energy spark across such gap to ignite such reaction mixture.