Method and apparatus for friction current joining

Patent metadata

Field	Value
Publication number	US-12103102-B2
Application number	US-202017605010-A
Country	US
Kind code	B2
Filing date	Apr 24, 2020
Priority date	Apr 25, 2019
Publication date	Oct 1, 2024
Grant date	Oct 1, 2024

Abstract

A method and apparatus for joining using friction and current, wherein the friction/current joining apparatus includes a friction device, a forging device, an electrical current source, and a programmable controller, as well as workpiece holders for the workpieces to be joined. The friction/current joining apparatus is controlled such that, in a contacting phase, the workpieces are initially moved along a process axis, and their mutually facing joining surfaces oriented transverse to a common process axis are brought into contact. In a grinding phase, while subjected to contact pressure by mutual relative movement, the joining surfaces, are ground together and made smooth. At the end of the grinding phase, the relative frictional movement is permanently stopped and, in a forging phase following the grinding phase, the workpieces are pressed together, plasticized, and joined while subjected to contact pressure on their contacting joining surfaces along the process axis, and subjected to conductive heating with electrical current.

First claim

What is claimed is:

1. A method for joining, using friction and current, two or more workpieces by grinding and by conductive heating with electrical current, the method comprising:
in a contacting phase, moving the workpieces along a process axis such that respective joining surfaces of the workpieces facing each other and oriented transverse to the process axis are brought into contact;
prior to or beginning with the contact of the joining surfaces, rotating the workpieces relative to each other in directions transverse to the process axis or about the process axis;
in a grinding phase that begins with the contact of the joining surfaces, grinding the workpieces against each other, subjected to contact pressure, due to the mutual relative movement at the joining surfaces such that the joining surfaces are made smooth without plasticizing the workpieces;
at the end of the grinding phase, stopping the relative grinding movement of the workpieces; and
in a forging phase directly following the grinding phase, forging, plasticizing, and joining the workpieces at their contacting joining surfaces, subjected to contact pressure along the process axis and subjected to immediate and continuous conductive heating by electric current without frictional relative movement of the workpieces.

2. The method of claim 1 , wherein the plasticizing, heating and joining of the workpieces subjected to contact pressure is effected at least primarily by the conductive electrical heating in the forging phase.

3. The method of claim 1 , wherein the grinding phase is performed substantially without subjecting the workpieces to pulsed electrical current.

4. The method of claim 1 , further comprising:
subjecting the workpieces to electrical current density in the grinding phase, wherein the electrical current density is selected to facilitate removal of uneven regions of the joining surfaces without adhesion; and
subjecting the workpieces to increased electrical current density in the forging phase, compared to the current density in the grinding phase.

5. The method of claim 1 , further comprising subjecting the workpieces to an adjusted, constant direct current.

6. The method of claim 1 , wherein the workpieces are subjected to a current density of between about 30 to 50 A/mm 2 in the forging phase.

7. The method of claim 1 , wherein:
the workpieces are subjected to the electrical current only at the end of the grinding phase; or
the workpieces are subjected to the electrical current only after the end of the grinding phase and the frictional relative movement.

8. The method of claim 1 , wherein the workpieces are subjected to the electrical current when they are at a standstill following the grinding phase.

9. The method of claim 1 , wherein, the workpieces are subjected, on the joining surfaces, to a contact pressure equivalent to the contact pressure during the grinding phase and the forging phase.

10. The method of claim 1 , wherein the workpieces are pressed together with a contact pressure of 125 MPa or less.

11. The method of claim 1 , further comprising:
detecting one or more physical parameters associated with the workpieces during the joining process; and
controlling at least one of the contacting, grinding, or forging phases according to the one or more detected physical parameters.

12. The method of claim 1 , further comprising at least one of:
electrically preheating the workpieces before joining the workpieces; or
electrically reheating the workpieces after joining the workpieces.

13. The method of claim 1 , further comprising one of:
demagnetizing an apparatus used for friction and current joining the workpieces; or
demagnetizing an apparatus used for friction and current joining the workpieces and demagnetizing the workpieces.

14. The method of claim 13 , wherein the demagnetization takes place with a direct-current demagnetization having a reverse polarity relative to the heating current for conductive heating.

15. The method of claim 14 , wherein the direct- current demagnetization is pulsed.

16. An apparatus for joining, using friction and current, two or more workpieces by grinding and by conductive heating with electrical current, the apparatus comprising:
workpiece holders for supporting the workpieces to be joined;
a friction device;
a forging device;
an electrical current source; and
a programmable controller having programming code designed to control the friction device, the forging device, and the electrical current source to carry out the method of claim 1 .

17. The apparatus of claim 16 , wherein:
the electrical current source is programmable, and is connected to the workpieces in an electrically conductive manner via current connections;
the current connections are arranged on at least one of the workpieces or the workpiece holders; and
each current connection has one or more electrodes.

18. The apparatus of claim 16 , wherein:
the electrical current source is designed as a direct-current current source with a constant current control for exact compliance with program-controlled electrical process currents; and
the electrical current source comprises a controllable or adjustable electrical converter.

19. The apparatus of claim 16 , wherein the forging device is designed to bring the workpieces being joined from an initially distant loading position along the process axis into mutual contact at their joining surfaces, and to generate a controllable contact force.

20. The apparatus of claim 16 , wherein:
the friction device comprises a machine head with a rotating drive for one of the workpiece holders;
the other workpiece holder being arranged on a counter holder; and
the machine head and the counter holder are mounted on a machine frame for movement relative to each other along the process axis.

Assignees

• Kuka Deutschland Gmbh

Inventors

• Herrich Jörg
• Habersetzer Stefan
• Schneider Klaus
• Burger Andreas
• Pham Andy

Classifications

• B23K20/121

  Control circuits therefor · CPC title

• B23K13/04

  by conduction heating · CPC title

• B23K11/02 Primary

  Pressure butt welding · CPC title

• B23K2103/14

  Titanium or alloys thereof · CPC title

• B23K28/02

  Combined welding or cutting procedures or apparatus · CPC title