Battery Case Lid Welding Gap Control for Seal Quality
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Solution Overview
Problem
Laser welding of battery cases often results in weld defects such as spatter, voids, and unwelded portions due to assembly failures and air entrapment, leading to reduced quality of the seal.
Innovation Solution
A method where the lid is fitted to the battery case with a pressing mechanism that creates a gap between the side wall and the lid, allowing the laser beam to be directed at the boundary portion, preventing spatter entry and air entrapment, and ensuring effective melting of metal oxide films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser welding is performed on the boundary portion between the battery case and lid, then the opening is sealed, but weld defects such as spatter, voids, and unwelded portions occur due to assembly failures and air entrapment
Solution Approach 1:
The method applies preliminary pressing to the side wall to create a gap between the side wall and lid before laser welding begins. This preliminary action prevents air entrapment and ensures proper alignment, eliminating the root causes of weld defects before the welding process occurs.
Solution Approach 2:
The gap created by pressing the side wall acts as an intermediary space that allows the laser beam to effectively reach the boundary portion and facilitates proper material flow during welding, preventing voids and unwelded portions while containing spatter.
2Weight of moving object
If the battery case and lid are formed of relatively thin metal members, then the battery is lightweight, but weld defects occur more frequently during laser welding
Solution Approach 1:
By pressing the side wall to create a gap before welding, the method ensures that thin metal members are properly positioned and aligned. This preliminary action prevents common welding defects in thin materials such as air entrapment and incomplete fusion, achieving reliable welds without compromising the lightweight design.
3Ease of manufacture
If a through-hole is formed between the side wall and lid due to assembly failure, then the structure is easier to manufacture, but spatter enters the battery case and weld defects occur
Solution Approach 1:
The gap created by pressing the side wall serves as an intermediary containment structure during welding. This gap prevents spatter from entering the battery case interior while still allowing the welding process to proceed effectively on thin metal members.
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 prevents weld defects by ensuring direct laser irradiation, reducing voids, and maintaining a sufficient amount of molten material, resulting in a high-quality seal.
Implementation Method 1
a boundary portion between the side wall and the lid is welded by irradiating a laser beam
Implementation Method 2
irradiating a laser beam in a direction from an outer side of the battery case toward the inner side of the battery case
Implementation Method 3
allowing the laser beam to be directed at the boundary portion, preventing spatter entry and air entrapment, and ensuring effective melting of metal oxide films
Data Source
AI summary
In a battery case sealing method, a lid is fitted to an opening of a battery case, and then a side wall on an inner side of the battery case and a side surface of the lid are brought into contact with each other. The side wall forms the opening. In a state where the side wall on the inner side of the battery case is in contact with the side surface of the lid, a boundary portion between the side wall and the side surface of the lid is welded by irradiating a laser beam in a direction from an outer side of the battery case toward the inner side of the battery case in a thickness direction of the lid.