Method of solid state welding and welded parts

• US 6,637,642 B1
• Filed: 08/13/2001
• Issued: 10/28/2003
• Est. Priority Date: 11/02/1998
• Status: Expired due to Term

• Current Assignee: Spinduction Weld, Inc.
• Original Assignee: Industrial Field Robotics
• Inventors: Lingnau, David
• Primary Examiner(s): Dunn, Tom
• Assistant Examiner(s): STONER, KILEY SHAWN
• Application Number:
  US09/807,398
• Time in Patent Office: 806 Days
• Field of Search: 228/112.1, 228/113, 228/114, 228/114.5, 228/2.1, 228/2.3, 219/600, 219/601, 219/602, 219/603, 219/604, 219/605, 219/606, 219/607, 219/608, 219/609, 219/610, 219/611, 428/544, 428/615, 403/282
• US Class Current: 228/112.1
• CPC Class Codes: B23K 13/00 Welding by high-frequency current heating
• CPC Class Codes: B23K 13/015 Butt welding
• CPC Class Codes: B23K 20/12 the heat being generated by friction; Friction welding
• CPC Class Codes: B23K 20/129 specially adapted for particular articles or workpieces
• CPC Class Codes: B23K 2101/06 Tubes
• CPC Class Codes: Y10T 428/12493 Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]

Abstract

A method of solid state welding for joining metal parts having opposed planar and parallel surfaces which includes quickly heating the opposed surfaces of the metal parts with a high frequency induction heater to the hot working temperature of the metal parts in a non-oxidizing atmosphere, continuously moving at least one of the parts relative to the other part generally parallel to the parallel surfaces of the parts, and quickly bringing the opposed surfaces of the parts together with an axial force approximately equal to the conventional friction welding forging force while continuing the relative motion of the parts until the absorbed kinetic energy is approximately equal to ten percent of the energy input required by conventional friction welding. The resultant weld is of a quality equal to or greater than normal friction welding but has a much smaller volume of flash and requires significantly less kinetic energy than conventional friction welding and is performed at rotational velocities well below the normal critical surface velocity of friction welding. The welded metal part includes a generally planar flash extending radially from the inner section of the opposed planar welded surfaces having a volume corresponding to a combined loss of length of less than 0.2 axial inches per inch of wall thickness. Thus, the disclosed solid state welding method is substantially more efficient than prior friction or other welding methods and results in an improved product.

Claims

1. A method of solid state welding for joining metal parts together, said metal parts having opposed generally planar and parallel surfaces, said method comprising the following steps:

quickly heating said opposed surfaces of said metal parts with a high frequency induction heater to the hot working temperature of said metal parts in a non-oxidizing atmosphere;

continuously moving at least one of said parts relative to the other of said parts generally parallel to said opposed planar and parallel surfaces; and

quickly bringing said opposed surfaces of said parts together while continuing to move at least one of said parts until the absorbed kinetic energy is approximately equal to 10% or less of the energy input prescribed by conventional friction welding to solid state weld said opposed surfaces of said metal parts together.

2. The method of solid state welding metal parts together as defined in claim 1, wherein said method includes heating said opposed surfaces to the said hot working temperature in a time of less than about 30 seconds.

3. The method of solid state welding metal parts together as defined in claim 1, wherein said method includes rotating said at least one of said parts at an initial perimeter velocity of about 4 ft/sec at the time of contact between said opposing metal parts.

4. The method of solid state welding metal parts together as defined in claim 3, wherein said method includes accelerating at least one of said parts to a rotational velocity equivalent to about 4 ft/sec either before or during the said induction heating step.

5. The method of solid state welding metal parts together as defined in claim 1, wherein said method includes welding said opposed surfaces of said metal parts together in about one second following heating and maintaining the axial force for an additional five seconds.

6. The method of solid state welding metal parts together as defined in claim 1, wherein said method includes rotating said at least one of said parts and welding said opposed surfaces of said metal parts together in less than about 4 revolutions following heating and maintaining the axial force until the temperature of the weld subsides to below the hot working temperature.

7. The method of solid state welding metal parts together as defined in claim 1, wherein said method includes induction heating said opposed surfaces to the said hot working temperature in a time of less than about 10 seconds.

8. The method of solid state welding metal parts together as defined in claim 1, wherein said method includes heating said opposed surfaces of said metal parts by an induction heater at a frequency of about 20 kilohertz or greater.

9. The method of solid state welding metal parts together as defined in claim 1, wherein said method includes heating said opposed surfaces of said metal parts by an induction heater at a frequency of about 20 kilohertz or greater such that the induction heating is confined to about the first 0.050 inches or less of said opposed surfaces of said metal parts.

10. The method of solid state welding metal parts together as defined in claim 1, wherein said method includes flooding said opposed surfaces of said metal parts with a non-reactive fluid while heating said opposed surfaces with an induction heater to the hot working temperature of said metal parts.

11. The method of solid state welding metal parts together as defined in claim 1, wherein said method further comprises the step of flooding said opposed surfaces of said metal parts with a non-oxidizing gas comprising primarily nitrogen gas while heating said opposed surfaces with an induction heater to the hot working temperature of said metal parts.

12. The method of solid state welding metal parts together as defined in claim 1, wherein said method further comprises the step of precoating said opposed surfaces of said metal parts with a protective barrier substance.

13. The method of solid state welding metal parts together as defined in claim 1, further comprises the step of maintaining said opposed surfaces in a substantial vacuum atmosphere.

14. The method of solid state welding ferromagnetic metal parts together as defined in claim 1, wherein said method includes induction heating said opposed surfaces to the Curie temperature in a time of less than about 10 seconds.

15. The method of solid state welding metal parts together as defined in claim 1, wherein said method includes heating said opposed surfaces in a vacuum with an induction heater to the hot working temperature of said metal parts.

16. The method of solid state welding metal parts together as defined in claim 1, wherein said metal parts are formed of a ferrous metal and said method includes precoating said opposed surface with less than 0.001″

thickness of an aluminum coating, while heating said opposed surfaces with an induction heater to the hot working temperature of said metal parts.

17. A method of solid state welding metal parts together having opposed generally coplanar parallel surfaces, said method comprising:

locating a high frequency induction heater between said opposed surfaces of said metal parts;

induction heating about the first 0.050 inches or less of said opposed surfaces of said metal parts with said high frequency induction heater at a frequency of 8 kilohertz or greater while simultaneously flooding said opposed surfaces of said metal parts with a non-oxidizing gas;

quickly removing said high frequency induction heater from between said opposed surfaces of said metal parts and continuously moving at least one of said parts relative to the other of said parts generally parallel to said opposed co-planar parallel surfaces; and

quickly bringing said opposed surfaces of said parts together while continuing to move said one at least one of said parts to friction weld said opposed surfaces of said metal parts together, wherein at least about 90% of the energy of welding is supplied by said high frequency induction heater and the balance of welding energy is supplied by conventional kinetic energy.

18. The method of solid state welding metal parts together as defined in claim 17, wherein the said method includes continuously moving said one of said parts in an with orbital motion.

19. The method of solid state welding metal parts together as defined in claim 17, wherein the method includes moving said one of said parts in a reciprocating motion.

20. The method of solid state welding metal parts together as defined in claim 17, wherein said method includes accelerating at least one of said parts to a rotational velocity of less than about 4 feet per second in less than one second.

21. The method of solid state welding metal parts together as defined in claim 17, wherein said method includes heating said opposed surfaces of said metal parts with said induction heater at a frequency of about 20 kilohertz or greater.

22. A metal part having opposed planar surfaces friction welded together including a generally planar flash extending radially from the intersection of said opposed planar friction welded surfaces having a volume corresponding to a combined loss of length of less than 0.2 axial inches per inch of wall thickness formed by the following process:

heating said opposed planar parallel surfaces with a high frequency induction heater to the hot working temperature of said metal part in a non-oxidizing atmosphere;

continuously moving one of said opposed planar surfaces relative to the other of said planar surfaces generally parallel to said opposed planar parallel surfaces; and

quickly bringing said opposed surfaces together with said forging force to friction weld said opposed surfaces together and said metal part.

23. The metal part defined in claim 22, wherein said method includes rotating said at least one of said opposed surfaces at a rotational velocity of less than 4 feet per second.

24. The metal part defined in claim 22, wherein said method includes heating said opposed surfaces by an induction heater at a frequency of greater than 8 kilohertz.

25. The metal part defined in claim 22, wherein said method includes heating said opposed surfaces by an induction heater having a frequency of about 20 kilohertz or greater such that the induction heating penetrates said surfaces less than 0.025 inches.

26. A method of solid state welding metal parts together having opposed generally co-planar parallel surfaces, said method comprising:

quickly heating said opposed surfaces of said metal parts with an induction heater at a frequency of about 20 kilohertz or greater such that the induction heating is confined to about the first 0.050 inches or less of said opposed surfaces of said metal parts;

continuously moving at least one of said metal parts relative to the other of said parts generally parallel to said opposed planar and parallel surfaces; and

quickly bringing said opposed surfaces of said parts together while continuing to move at least one of said parts until the absorbed kinetic energy is approximately equal to 10% or less of the energy input prescribed by conventional friction welding to solid state weld said opposed surfaces of said metal parts together.

27. A method of solid state welding metal parts together having opposed generally coplanar parallel surfaces, said method comprising:

locating a high frequency induction heater between said opposed surfaces of said metal parts;

induction heating said opposed metal surfaces of said metal parts with said high frequency induction heater at a frequency of 8 kilohertz or greater in a non-oxidizing atmosphere;

quickly moving said high frequency induction heater from between said opposed surfaces of said metal parts and continuously moving at least one of said metal parts relative to the other of said metal parts generally parallel to said opposed co-planar parallel surfaces; and

quickly bringing said opposed surfaces of said metal parts together while continuing to move said at least one of said parts to friction weld said opposed surfaces of said metal parts wherein a combined loss of length of said metal parts resulting from flash is less than 0.2 axial inches per inch of wall thickness of said metal parts.