Gas-Powder Flow Turbulent Mixing for Coated Metal Weld Seam Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Coated metal sheets welded together often result in weakened weld seams due to the incorporation of primary coating constituents like aluminum or zinc, which form compounds with iron, reducing the strength and potentially causing failure, and existing stripping methods are complex and expensive.
Innovation Solution
A method involving the addition of pulverulent welding additives in the form of a gas-powder flow to the weld melt, with a high output speed to achieve turbulent mixing and homogeneous alloying, using particles of 20 μm to 160 μm size, and directing the gas-powder flow obliquely to create flow eddies, along with a protective gas atmosphere to prevent oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If coating constituents (aluminum, zinc) are present in the weld melt, then the coated metal sheets can be welded directly, but the weld seam strength is reduced due to formation of low-strength compounds
Solution Approach 1:
The harmful coating constituents (aluminum, zinc) are extracted from the weld seam zone by blowing inert gas at high speed through the weld melt, removing them before they can form low-strength compounds and thereby preserving weld seam strength
Solution Approach 2:
The physical state of the weld melt is changed by introducing high-speed gas flow, which creates turbulence and enhances mixing, allowing the coating constituents to be dispersed and removed effectively without compromising the base metal welding
2Strength
If stripping methods are used to remove coating at edges, then weld seam strength is improved, but the process complexity and cost increase
Solution Approach 1:
The mechanical stripping process is replaced by a gas dynamic process where high-speed inert gas flow directly removes coating constituents from the weld melt, eliminating the need for complex mechanical stripping equipment and reducing process complexity
Solution Approach 2:
Compressed inert gas is utilized to create high-speed gas flow through the weld zone, providing a simple yet effective means to remove harmful coating constituents without requiring complex mechanical or chemical stripping systems
3Productivity
If welding time is short (6-125 ms in laser welding), then productivity is improved, but sufficient mixing of welding additive with base metal is not achieved
Solution Approach 1:
High-speed gas flow creates turbulence and eddies in the weld melt, producing a mixing effect similar to mechanical vibration that rapidly homogenizes the alloy composition even during very short welding times, thereby maintaining both productivity and compositional stability
Solution Approach 2:
The weld material undergoes phase transition between solid and liquid states, and the high-speed gas flow exploits the liquid phase to achieve rapid mixing and homogenization before solidification, enabling sufficient alloying within the brief melt duration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures a strong, homogeneous weld seam without loss of strength, even in short welding times, by achieving complete mixing of the additive with the metal, preventing the formation of low-strength compounds and maintaining the integrity of the weld.
Implementation Method 1
the gas-powder flow leaving the flow duct is directed towards the weld melt and has an output speed of at least 2 m/s, in such a way the welding additive is mixed together turbulently with the weld melt, flow eddies forming in the weld melt during said mixing
Data Source
AI summary
A method for joint-welding coated metal sheets in a butt joint. At least one pulverulent welding additive in the form of a gas-powder flow is added to the weld melt via at least one flow duct, such that the gas-powder flow leaving the flow duct is directed towards the weld melt at a speed of at least 2 m/s, such that the welding additive mixes turbulently with the weld melt and flow eddies form in the weld melt. A device including at least one welding head for producing and/or focussing an energy beam and at least one flow duct for supplying gas-powder flow, the flow duct having a longitudinal axis, the longitudinal axis and the beam axis of the energy beam being at an angle between 15 and 75 degrees. The flow duct is adapted to set the gas powder flow to a speed of at least 2 m/s.