Laser welding stacked foils
AssigneeCorelase Oy
InventorsMatti Närhi, Henri Pajukoski
Life of this patent
Estimating the term…
Abstract
A method for laser keyhole welding a stack of metal foils to a metal tab is disclosed. The method independently adjusts power in a focused center beam and power in a focused annular beam to form a weld through all the foils and the tab. The annular beam provides sufficient power to heat the metal to about melting temperature, widen a mouth of a keyhole, and stabilize a melt pool. The center beam provides sufficient additional power to form the keyhole. The power of the annular beam is sustained for a longer time than the power of the center beam. A plurality of such welds is formed to provide mechanical strength and electrical conductivity.
Claims32
A method for laser welding a plurality of copper foils onto a copper tab, comprising the steps of:
- assembling the foils into a stack and compressing the stack of foils and the tab to form a workpiece;
- directing a focused beam of laser radiation to a surface of the workpiece at a location-to-be-welded, the focused beam including a center beam and a concentric annular beam;
- ramping the power of the annular beam up to a first power;
- sustaining the power of the annular beam for a first time that is sufficient to heat the surface of the workpiece at the location-to-be-welded to at least 1100 kelvin;
- ramping the power of the center beam up to a second power, the center beam reaching the second power after the surface of the workpiece at the location-to-be-welded reaches 1100 kelvin;
- and
- sustaining the power of the center beam for a second time that is sufficient to melt through all the foils and the tab, thereby forming a weld that joins all the foils and the tab.
A method for laser welding a plurality of aluminum foils onto an aluminum tab, comprising the steps of:
- assembling the foils into a stack and compressing the stack of foils and the tab to form a workpiece;
- directing a focused beam of laser radiation to a surface of the workpiece at a location-to-be-welded, the focused beam including a center beam and a concentric annular beam;
- ramping the power of the annular beam up to a first power while ramping the power of the center beam up to a second power;
- sustaining the power of the annular beam for a first time;
- and
- sustaining the power of the center beam for a second time, then ramping down the power of the center beam, the first time being longer than the second time;
- wherein the second time is sufficient to melt through all the foils and the tab, thereby forming a weld that joins all the foils and the tab.
Dependencies are inferred from the claim text.