Multi-Stage Ultrasonic Node Welding for Large Conductor Cross-Sections
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Solution Overview
Problem
Ultrasonic welding of nodes with large cross-sections faces challenges due to inhomogeneous energy distribution, leading to inconsistent and potentially damaged connections, particularly in high-current applications like electric or hybrid vehicles.
Innovation Solution
A method using an ultrasonic welding device with an adjustable compression space, allowing for two-stage welding processes with predetermined width settings and tolerance values to ensure homogeneous energy distribution and prevent tilting or jamming, resulting in durable and conductive connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-stage ultrasonic welding process is used for nodes with large cross-sections, then the welding process is simple and quick, but the ultrasonic energy distribution becomes inhomogeneous leading to inconsistent welding quality
Solution Approach 1:
The welding process is divided into multiple stages, with each stage welding a specific portion of the node. The sonotrode welds conductor sections in sequential steps, allowing ultrasonic energy to be concentrated on smaller areas at each stage rather than attempting to weld the entire large cross-section at once. This segmentation ensures homogeneous energy distribution and consistent welding quality across the entire node.
2Device complexity
If the compression chamber width is fixed for multi-stage welding, then the device structure is simple, but the sonotrode may tilt or jam during subsequent welding stages
Solution Approach 1:
The compression chamber width is made adjustable between welding stages. After completing a welding stage, the side elements are moved apart to increase the chamber width, creating clearance that prevents the sonotrode from tilting or jamming during the next stage. This dynamic adjustment maintains process reliability while keeping the device structure relatively simple.
3Ease of manufacture
If multiple welding stages are performed with fixed compression chamber dimensions, then the welding process is straightforward, but wire breaks and discoloration occur due to sonotrode tilting and jamming
Solution Approach 1:
The compression chamber width is dynamically increased between welding stages by moving the side elements apart. This creates necessary clearance that prevents the sonotrode from tilting or jamming during subsequent welding operations, thereby eliminating wire breaks and discoloration while maintaining process simplicity.
4Area of stationary object
If the compression chamber width is increased for larger nodes, then larger cross-sections can be accommodated, but ultrasonic energy distribution becomes inhomogeneous
Solution Approach 1:
The welding process is segmented into multiple stages, with each stage handling a specific portion of the large cross-section. By dividing the welding task across multiple sequential operations, the sonotrode can maintain consistent ultrasonic energy distribution on smaller areas at each stage, ensuring homogeneous welding quality even for large overall node cross-sections.
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 ensures consistent, high-quality welding of nodes with large cross-sections, reducing wire breaks and discoloration, increasing process reliability, and allowing for efficient production of high-current connectors.
Implementation Method 1
a sonotrode (102) for generating ultrasonic vibrations
Implementation Method 2
This is a special form of friction welding in which components to be welded are brought into contact with each other's surfaces and moved against each other under low pressure and high-frequency mechanical vibrations
Implementation Method 3
Through plastic flow, the joining partners can then interlock or hook into each other close to the surface without the materials of the joining partners necessarily melting
Data Source
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AI summary
The invention relates to a method for welding a node by means of an ultrasonic welding device (100), wherein the ultrasonic welding device (100) comprises a sonotrode (102) for generating ultrasonic vibrations, an anvil (104), a first lateral element (106), a second lateral element (108) and a compression chamber (110), wherein the height thereof can be adjusted by varying a distance between the sonotrode (102) and the anvil (104), and the width (B) thereof can be adjusted by varying a distance between the first lateral element (106) and the second lateral element (108). The method comprises the following steps: arranging first conductor sections to be welded of at least two electrical conductors in the compression chamber (110); adjusting the width (B) of the compression chamber (110) to a predefined value for a first welding process; carrying out the first welding process by activating the sonotrode (102) and pressing together the first conductor sections between the sonotrode (102) and the anvil (104), wherein the first conductor sections are welded to form a first node (300); arranging a second conductor section (400) to be welded of at least one other electrical conductor (402) and the first node (300) in the compression chamber (110); adjusting the width (B) of the compression chamber (110) to a predefined value for a second welding process, wherein the width (B) of the compression chamber (110) for the second welding process is greater than the width (B) of the compression chamber (110) for the first welding process by a predefined tolerance value (AB); and carrying out the second welding process by reactivating the sonotrode (102) and pressing together the first node (300) and the second conductor section (400) between the sonotrode (102) and the anvil (104), wherein the first node (300) and the second conductor section (400) are welded together to form a second node.