Battery Sealing Rivet Welding for Wider Clearance Tolerance
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Solution Overview
Problem
Existing continuous laser welding methods for sealing rivets in batteries require precise fitting clearance, which is challenging to achieve and affects welding quality and reliability.
Innovation Solution
A novel welding method that includes a primary trajectory line along the outer periphery of the sealing rivet and a secondary trajectory line with controlled rotation or reciprocation, expanding the molten pool width and ensuring a wider, flat-bottomed welding mark, combined with controlled surface roughness to enhance laser absorption and welding consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If continuous laser welding is used for sealing rivet assembly, then welding strength is improved, but fitting clearance requirements become too strict
Solution Approach 1:
The patent applies periodic action by using pulse laser welding instead of continuous laser welding. The welding process is divided into periodic pulses with specific duty cycles (10%-50%), allowing the material to heat and cool in cycles. This periodic heating creates a wider, more tolerant molten pool that accommodates larger fitting clearances while maintaining weld strength, directly resolving the contradiction between welding strength and fitting clearance precision.
Solution Approach 2:
The patent changes key welding parameters including laser power (50-200W), pulse width (10-100ms), and duty cycle (10%-50%) to optimize the welding process. By adjusting these parameters, the molten pool width is increased and the fitting clearance tolerance is relaxed from traditional tight tolerances to 0.1-0.5mm, resolving the contradiction between maintaining welding strength and reducing manufacturing precision requirements.
2Manufacturing precision
If molten pool width is increased to reduce fitting clearance requirements, then manufacturing tolerance is improved, but welding process complexity increases
Solution Approach 1:
The patent achieves wider molten pool with relaxed tolerances by changing laser process parameters (power, pulse width, duty cycle, scanning speed) rather than complicating the welding device structure. The control system uses programmable parameter sequences to automatically manage the welding process, keeping device complexity low while achieving the desired molten pool characteristics and 0.1-0.5mm fitting clearance tolerance.
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 reduces the need for precise fitting clearance, improves welding strength and reliability, and enhances the sealing performance of the battery by forming a wider molten pool with a flat bottom, thus addressing the limitations of traditional continuous laser welding.
Implementation Method 1
Laser welding is a secure and commonly used assembly method for sealing rivets
Implementation Method 2
the molten pool formed by the existing continuous laser welding
Data Source
AI summary
A secondary battery, battery pack, and an electronic apparatus are provided. The secondary battery includes an electrode assembly, a casing, an electrode post, a sealing rivet, and a welding mark. The electrode assembly is accommodated in the casing, and one end of the casing has an opening portion. An end portion of the electrode post away from the electrode assembly protrudes from the casing through the opening portion, and the end portion of the electrode post is provided with a groove. The sealing rivet is matched and embedded in the groove. The sealing rivet is welded and fixed to the electrode post through the welding mark located on a connection portion of an end surface of an outer periphery of the sealing rivet and an end surface of the end portion of the electrode post.