Spot Weld Tempering Layout for Robust Nugget Heat Treatment
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Solution Overview
Problem
Conventional post heat methods and two-stage energization methods for spot welding high-strength sheet steels have narrow suitable conditions, making them susceptible to external factors like debris, electrode wear, and misalignment, leading to uneven current density and reduced robustness, which complicates their application in manufacturing sites and affects the productivity and quality of welded joints.
Innovation Solution
A method involving a tempering device with electrodes positioned on opposite sides of a nugget, passing current through a broad region including the nugget and heat affected zone in an oblique direction, ensuring a stable and robust tempering process by increasing the energization path length and maintaining consistent contact marks on the steel sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional post heat methods or two-stage energization methods are used to temper the weld, then the joint strength is improved, but the range of suitable conditions is narrow and the process is highly susceptible to external factors such as debris, electrode wear, and misalignment
Solution Approach 1:
The invention changes the dimension of the energization path by positioning electrodes laterally at outer sides of the nugget rather than vertically above and below it. This lateral positioning in the sheet-plane direction creates a longer, more stable current path that passes through the heat affected zone, making the tempering process less sensitive to vertical misalignment and external factors while still achieving the desired tempering effect for improved joint strength
Solution Approach 2:
The invention modifies the geometric parameters of the electrode-nugget relationship by positioning electrodes at a specified lateral distance from the nugget center. This parameter change extends the energization path length and shifts the current distribution pattern, creating a more robust tempering process that maintains stability across varying external conditions while achieving the required joint strength
2Temperature
If electrodes are positioned vertically above and below the nugget for post heat, then the tempering effect is achieved, but the current density becomes uneven and the process is sensitive to misalignment and external factors
Solution Approach 1:
The invention transitions from vertical electrode positioning to lateral positioning in the sheet-plane direction. This dimensional change redistributes the current path to pass through the heat affected zone along the lateral axis, creating more uniform current density distribution and reducing sensitivity to vertical misalignment while maintaining effective tempering temperatures
Solution Approach 2:
The heat affected zone acts as an intermediary medium through which the current passes laterally between the electrodes positioned at outer sides of the nugget. This intermediary path ensures uniform current distribution through the zone requiring tempering, achieving consistent temperature distribution and reducing sensitivity to positioning variations
3Device complexity
If the energization path is short and passes directly through the nugget, then the welding process is simple, but the tempering process is highly sensitive to external factors and current density control is difficult
Solution Approach 1:
The invention extends the energization path by positioning electrodes laterally at outer sides of the nugget, creating a longer current path that passes through the heat affected zone. This dimensional reconfiguration increases the path length without adding complex equipment, achieving improved robustness and current density control while maintaining process simplicity
Solution Approach 2:
The electrode positioning is pre-configured to create an optimized energization path that passes through the heat affected zone before nugget formation completes or immediately afterward. This preliminary arrangement of electrodes at lateral positions ensures that the tempering current follows a stable, extended path that is inherently less sensitive to external factors, eliminating the need for complex real-time adjustments
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 enhances the robustness of the welded joint by allowing a broader range of suitable current conditions, reducing the impact of external factors and achieving uniform tempering across the nugget and heat affected zone, thereby improving joint strength and stability.
Implementation Method 1
passing a current through the welded joint between the first electrode and the second electrode
Data Source
AI summary
A welded joint manufacturing method includes: abutting a first electrode against a first steel sheet of a welded joint at a site A, which is a location at an outer side of a nugget in a sheet-plane direction in a plane running parallel to the first steel sheet; abutting a second electrode against a second steel sheet at a site B, which is a location at an outer side of the nugget in a sheet-plane direction in a plane running parallel to the first steel sheet of the welded joint, and positioned on an opposite side of the nugget from the site A; and passing a current through the welded joint between the first electrode and the second electrode.