Copper-Aluminum Flame Brazing with Mixed-Gas Ratio Control
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Solution Overview
Problem
Copper-aluminum welding faces challenges with overheating or underheating of aluminum components and uneven penetration of brazing materials due to significant differences in physical and chemical properties, affecting welding quality and efficiency.
Innovation Solution
A flame brazing control method using a flame generated from the combustion of natural gas, air, and oxygen, with controlled molar flow ratios, and an automatic brazing apparatus featuring integrated gas delivery systems and flow controllers to achieve precise flame control, ensuring optimal heating conditions for copper-aluminum welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If oxygen is used as combustion-assisting gas to achieve high heating efficiency, then heating speed is improved, but aluminum components overheat or underheat and brazing material penetration becomes uneven
Solution Approach 1:
The patent changes the chemical composition parameter of the combustion gas from pure oxygen to a mixed gas of oxygen and air. This parameter change moderates the combustion intensity, allowing the flame temperature to remain sufficiently high for efficient heating while preventing excessive temperature that would cause aluminum overheating or uneven brazing material penetration. The mixed gas composition optimizes the balance between heating speed and temperature control precision.
2Manufacturing precision
If air is used as combustion-assisting gas to avoid aluminum overheating, then temperature control is improved, but copper component crystallographic structure changes and welding quality deteriorates
Solution Approach 1:
The patent adjusts the oxygen content parameter in the combustion gas to an optimal range (21-40% oxygen concentration). This parameter change ensures that the flame produces sufficient heat to prevent copper crystallographic structure changes while still providing adequate temperature control to prevent aluminum overheating. The controlled oxygen content creates a flame with appropriate thermal intensity for welding dissimilar metals with different thermal properties.
3Productivity
If high flame intensity is used to reduce heating time and improve productivity, then welding efficiency is improved, but heating uniformity deteriorates
Solution Approach 1:
The patent modifies the combustion gas composition parameter to use oxygen-air mixed gas, which produces a flame with moderate intensity and better heat distribution characteristics. This parameter change allows for reduced heating time through optimized flame characteristics while maintaining heating uniformity. The mixed gas flame provides more distributed heat transfer compared to concentrated high-intensity oxygen flames.
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
The method and apparatus enhance welding quality, qualified rate, and efficiency by preventing overheating, underheating, and crystallographic changes, achieving a first-time pass rate of over 99% and improving the uniformity and stability of the brazing process.
Implementation Method 1
a flame generated from the combustion of natural gas, air, and oxygen is used as the heat source
Implementation Method 2
The adjusted air and fuel gas are uniformly mixed in a mixer and then delivered to the welding gun system
Implementation Method 3
the brazing material is melted and is metallurgically reacted with the weldment metal, and the brazing material infiltrates the weldment metal by means of capillary action to realize connection
Data Source
AI summary
Disclosed is a flame brazing control method for copper-aluminum welding, characterized by using a flame generated from the combustion of natural gas, air and oxygen as the heat source, the molar flow ratio of natural gas, air and oxygen is controlled within a range of 1:10-22:0.3-2.2. Further disclosed is an automatic brazing apparatus for copper-aluminum welding, characterized by using a flame generated from the combustion of natural gas, air and oxygen as the heat source, includes three gas delivery systems for natural gas, air and oxygen, a mixer for mixing the three gas, and integrated flow controllers for the electromagnetic valves and flow valves in the three gas delivery systems.