Magnetic Pulse Soldering of Sheet Stacks for High-Conductivity Joints
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Solution Overview
Problem
Current welding techniques for assembling thin metal sheets and thick plates, such as those used in lithium-ion batteries, fail to ensure adequate electrical conductivity due to insufficient compression and potential local heating, leading to poor weld quality and conductivity issues.
Innovation Solution
A magnetic pulse welding method is employed, where through-holes are created in the stack of sheets, and metal plates are positioned on either side to sandwich the stack, using a coil to generate a magnetic field that exerts pressure on the plates, creating a direct contact and annular weld at the holes, ensuring a solid-state assembly without melting, thus maintaining sheet position and enhancing conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic welding or laser welding is used to assemble sheets and plates, then the assembly is rapid and economical, but the sheets are not sufficiently compressed and local heating creates holes that deteriorate weld quality and electrical conductivity
Solution Approach 1:
The patent replaces thermal welding processes (ultrasonic and laser welding) with magnetic pulse welding, which uses electromagnetic forces to generate mechanical impact and compression. The coil generates a magnetic field that exerts pressure on the plates, pressing them against the sheets without thermal input, thereby avoiding heat-induced holes while ensuring sufficient compression for good electrical contact
Solution Approach 2:
The patent changes the fundamental welding parameter from thermal energy to electromagnetic energy. By using magnetic pulse welding instead of ultrasonic or laser welding, the process achieves both rapid assembly and high reliability by eliminating local heating effects that create conductive defects, while maintaining the speed advantage through the rapid nature of magnetic pulse application
2Ease of manufacture
If conventional welding techniques are used, then assembly is economical, but local heating leads to hole creation that decreases electrical conductivity
Solution Approach 1:
The patent substitutes thermal welding mechanisms with electromagnetic-based magnetic pulse welding. The coil generates a magnetic field that creates mechanical pressure on the plates, forcing direct contact with sheets without thermal input. This eliminates hole formation from local heating while maintaining manufacturing simplicity and cost-effectiveness
Solution Approach 2:
The patent converts the potentially harmful effect of requiring strong compression (which could damage thin sheets) into a beneficial outcome by using controlled magnetic pulse pressure. The magnetic field generates sufficient compression force to ensure good electrical contact and prevent hole formation, while the pulsed nature of the magnetic field prevents excessive pressure that could damage the sheets
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 method effectively improves electrical conductivity by ensuring direct contact between plates and sheets, minimizes energy losses, and allows for the assembly of materials with different melting points, such as copper and aluminum, without delamination, while avoiding the drawbacks of conventional welding.
Implementation Method 1
the welding of the plates-stack assembly is carried out by subjecting the working zone to a magnetic field of the coil
Implementation Method 2
The magnetic field coming from the active portion of the coil exerts, at the working zone, a pressure on the plate closest to the coil
Data Source
AI summary
A method for the magnetic pulse soldering of an item having a stack of sheets consisting of a metal material. At least one hole through a thickness of the stack is formed. The first and second plates, both consisting of a metal material, are arranged on either side of the stack. A covering area covering at least one through-hole is formed. The plates-stack assembly is positioned opposite an active part of a coil such that a working area of the covering area faces the active part of the coil and the working area covering at least one hole. The working area is subjected to a magnetic field until the assembly is joined. While the working area is subjected to the magnetic field, pressure is exerted on the first plate, in the region of at least one hole, pressing the first plate against the second plate.