IP Verse

Methods And Systems For Welding Copper And Other Metals Using Blue Lasers

Patent No. US11612957 (titled "Methods And Systems For Welding Copper And Other Metals Using Blue Lasers") was filed by Blue 425 Llc on Dec 30, 2019.

What is this patent about?

’957 is related to the field of laser material processing, specifically laser welding of metals such as copper, aluminum, and stainless steel. Traditional infrared (IR) laser welding of copper presents challenges due to copper's high reflectivity at IR wavelengths, leading to inefficient energy coupling, spatter, porosity, and micro-explosions. This is particularly problematic in applications like battery manufacturing, where high-quality, high-speed welds are crucial for performance and reliability. Current methods to mitigate these issues, such as modulating laser power or using vacuum environments, have limitations in terms of processing windows and weld consistency.

The underlying idea behind ’957 is to leverage the higher absorption rate of copper and other metals at blue laser wavelengths (approximately 400-500 nm) to achieve more efficient and stable welding. By using a blue laser, the energy couples more effectively into the material, reducing reflectivity issues and enabling better control over the welding process. This approach aims to minimize or eliminate common defects associated with IR laser welding, such as spatter and porosity, while also potentially increasing welding speeds.

The claims of ’957 focus on a method for laser welding multiple pieces of copper foil using a blue laser beam. The method involves positioning the foils in a welding stand, applying a clamping force, and directing a blue laser beam with specific properties (power, beam parameter product, spot size, average and peak intensity) to lap weld the foils together. A key aspect is the use of a non-oxidizing clearing gas to remove plume material and prevent oxidation, with the welding speed, clamping force, and gas flow rate being predetermined to achieve a weld free of visible splatter and porosity. The claims also extend to welding other metals beyond copper.

In practice, the invention uses a blue laser system to deliver a focused beam onto the metal workpiece. The clamping force ensures good contact between the metal pieces, while the clearing gas protects the weld area from oxidation and removes vaporized material that could interfere with the laser beam. By carefully controlling the laser parameters and gas flow, the process can be optimized to create a stable weld puddle and achieve full penetration without excessive spatter or porosity. The laser can operate in either conduction mode, where heat is transferred through the material, or keyhole mode, where the laser creates a vapor cavity that enhances penetration.

The differentiation from prior approaches lies primarily in the use of a blue laser for welding these metals. While IR lasers have been used, the inherent reflectivity of copper at those wavelengths necessitates higher power and more complex control strategies. The blue laser's higher absorption rate allows for lower power levels, simpler process control, and potentially higher welding speeds. Furthermore, the invention emphasizes the importance of plume management through the use of a clearing gas, which is crucial for maintaining a stable and clean welding environment, especially when working with materials prone to oxidation or vaporization. This combination of blue laser and plume control leads to improved weld quality and process reliability.

How does this patent fit in bigger picture?

Technical landscape at the time

In the mid-2010s when '957 was filed, laser welding systems commonly relied on infrared lasers, at a time when welding copper was typically implemented using high power levels to overcome high reflectivity. At this time, controlling spatter and porosity during copper welding was non-trivial, when hardware or software constraints made precise modulation of laser power challenging.

Novelty and Inventive Step

The claims were objected to for informalities and rejected under 35 U.S.C. 112(b) as being indefinite. The examiner indicated that claims 1-20 would be allowable if rewritten or amended to overcome the rejections. The prosecution record does NOT describe the technical reasoning or specific claim changes that led to allowance.

Claims

This patent contains 20 claims, with independent claims numbered 1, 12, and 20. The independent claims are directed to methods of laser welding multiple metal pieces together using a blue laser beam with specific power, beam parameter product, spot size, and intensity characteristics, while also employing a non-oxidizing beam clearing gas. The dependent claims generally specify further details, limitations, or variations of the methods described in the independent claims, such as beam type, wavelength, clearing gas composition, wobble-free welding, number and thickness of foil pieces, welding speed, metal types, weld types, and welding stand features.

Key Claim Terms New

Definitions of key terms used in the patent claims.

Term (Source)Support for SpecificationInterpretation
Beam parameter product
(Claim 1, Claim 12, Claim 20)		“There is no explicit definition of "beam parameter product" in the specification. However, the claims specify a maximum value for this parameter.”A property of the laser beam, limited to about 44 mm mrad and less.
Blue laser beam
(Claim 1, Claim 12, Claim 20)		“As used herein, unless expressly stated otherwise, the terms “blue laser beams”, “blue lasers” and “blue” should be given their broadest meaning, and in general refer to systems that provide laser beams, laser beams, laser sources, e.g., lasers and diodes lasers, that provide, e.g., propagate, a laser beam, or light having a wavelength from about 400 nm to about 500 nm. Typical blue lasers have wavelengths in the range of about 405-495 nm. Blue lasers include wavelengths of 450 nm, of about 450 nm, of 460 nm, of about 470 nm. Blue lasers can have bandwidths of from about 10 pm (picometer) to about 10 nm, about 5 nm, about 10 nm and about 20 nm, as well as greater and smaller values.”A laser beam having a wavelength from about 400 nm to about 500 nm.
Clamping force
(Claim 1, Claim 12, Claim 20)		“Thus, there is provided a system for and a method of laser welding a plurality of cooper foils together, the method including the steps of: positioning a plurality of pieces of cooper foil in a welding stand; wherein the foil contains at least about 50% cooper; exerting a clamping force on the plurality of pieces of cooper foil to clamp the pieces of foil together in the welding stand; directing a blue laser beam along a laser beam path at the plurality of pieces of cooper foil, wherein the laser beam has the following properties: (i) at least 500 Watts of power; (ii) a beam parameter product of about 44 mm mrad and less; (iii) a spot size of about 400 μm and less; (iv) an average intensity of at least of about 400 kW/cm2; (v) a peak intensity of at least about 800 kW/cm2; and the blue laser beam lap welding the plurality of pieces of cooper foil together at a welding speed; and, providing a non-oxidizing beam clearing gas in a space along the laser beam path where the laser beam travels in free space from an optical element to the plurality of pieces of cooper foil; wherein clearing gas removes plume material from the laser beam path and prevents oxidation of the plurality of pieces of copper foil; wherein the welding speed, clamping force, and a flow rate of the non-oxidizing clearing glass, are predetermined to thereby provide a lap weld having no visible splatter and no visible porosity.”A force exerted on the plurality of pieces of metal to clamp the pieces of metal together in the welding stand.
Non-oxidizing beam clearing gas
(Claim 1, Claim 12, Claim 20)		“Providing a non-oxidizing beam clearing gas in a space along the laser beam path where the laser beam travels in free space from an optical element to the plurality of pieces of cooper foil; wherein clearing gas removes plume material from the laser beam path and prevents oxidation of the plurality of pieces of cooper foil; wherein the welding speed, clamping force, and a flow rate of the non-oxidizing clearing glass, are predetermined to thereby provide a lap weld having no visible splatter and no visible porosity.”A gas provided in the laser beam path to remove plume material and prevent oxidation of the copper foil.
Welding speed
(Claim 1, Claim 12, Claim 20)		“Thus, there is provided a system for and a method of laser welding a plurality of cooper foils together, the method including the steps of: positioning a plurality of pieces of cooper foil in a welding stand; wherein the foil contains at least about 50% cooper; exerting a clamping force on the plurality of pieces of cooper foil to clamp the pieces of foil together in the welding stand; directing a blue laser beam along a laser beam path at the plurality of pieces of cooper foil, wherein the laser beam has the following properties: (i) at least 500 Watts of power; (ii) a beam parameter product of about 44 mm mrad and less; (iii) a spot size of about 400 μm and less; (iv) an average intensity of at least of about 400 kW/cm2; (v) a peak intensity of at least about 800 kW/cm2; and the blue laser beam lap welding the plurality of pieces of cooper foil together at a welding speed; and, providing a non-oxidizing beam clearing gas in a space along the laser beam path where the laser beam travels in free space from an optical element to the plurality of pieces of cooper foil; wherein clearing gas removes plume material from the laser beam path and prevents oxidation of the plurality of pieces of cooper foil; wherein the welding speed, clamping force, and a flow rate of the non-oxidizing clearing glass, are predetermined to thereby provide a lap weld having no visible splatter and no visible porosity.”The speed at which the laser beam welds the pieces of metal together.

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US11612957

BLUE 425 LLC
Application Number
US16730852
Filing Date
Dec 30, 2019
Status
Granted
Expiry Date
Aug 16, 2037
External Links
Slate, USPTO, Google Patents