Cylindrical Battery Case Ironing for Low-Roughness Corrosion Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for manufacturing cylindrical battery cases fail to effectively reduce surface roughness, leading to poor corrosion resistance, especially in high-temperature and high-humidity environments, which is critical for electric vehicle applications.
Innovation Solution
A multi-step manufacturing process involving nickel coating, thermal treatment, and multiple deep-drawing and ironing processes to achieve a surface roughness of 0.1µm or less, enhancing corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional deep-drawing process is performed to form the battery case, then the manufacturing process is simple, but the surface roughness increases and corrosion resistance deteriorates
Solution Approach 1:
The conventional single-stage deep-drawing process is segmented into multiple stages: a first deep-drawing process to form an intermediate cup body, followed by a first ironing process, then a second deep-drawing process to form the final battery case body, and finally a second ironing process. This segmentation allows each stage to be optimized independently, with ironing processes specifically targeted at reducing surface roughness between drawing stages, thereby achieving Ra ≤ 0.1 µm without excessive overall process complexity.
Solution Approach 2:
The first ironing process is performed as a preliminary action between the first and second deep-drawing processes. This intermediate ironing step prepares the surface of the intermediate cup body by reducing its roughness before the final shaping operations, ensuring that the final battery case body achieves the target surface roughness of Ra ≤ 0.1 µm while maintaining manufacturing efficiency.
2Reliability
If the surface roughness is reduced through multiple ironing processes, then corrosion resistance improves, but manufacturing time increases
Solution Approach 1:
The deep-drawing and ironing processes are merged into an integrated multi-stage manufacturing sequence where drawing and ironing operations are alternated and combined. The first deep-drawing and first ironing processes are combined to form the intermediate cup body, and the second deep-drawing and second ironing processes are combined to form the final battery case body. This merging allows surface roughness reduction to occur during the natural flow of manufacturing operations rather than as separate additional steps, achieving Ra ≤ 0.1 µm with acceptable manufacturing time.
3Reliability
If multiple deep-drawing and ironing processes are performed, then surface glossiness is maintained and corrosion characteristics improve, but the number of process steps increases
Solution Approach 1:
The manufacturing process is segmented into two main phases: Phase 1 includes the first deep-drawing process and first ironing process to create the intermediate cup body with reduced surface roughness; Phase 2 includes the second deep-drawing process and second ironing process to form the final battery case body with Ra ≤ 0.1 µm. This segmentation into two balanced phases achieves the dual goals of improved corrosion characteristics and maintained surface glossiness while keeping the number of process steps manageable at four major operations.
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 process significantly reduces surface roughness and improves corrosion resistance, maintaining surface glossiness and reducing internal resistance, thereby enhancing battery performance and durability.
Implementation Method 1
a first step of forming a nickel coating layer on at least one surface of a steel sheet
Implementation Method 2
a second step of thermally treating the steel sheet subjected to the first step in a reducing atmosphere
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Disclosed herein is a method of manufacturing a cylindrical battery case that is capable of performing an ironing process, which is one of the processes of manufacturing the battery case, a plurality of times in order to decrease the surface roughness of the battery case, thereby improving the corrosion characteristics of the battery case. The surface roughness of the cylindrical battery case is decreased by performing a thickness reducing process when a process for forming the outer circumferential surface of a body of the cylindrical battery case is performed at the time of manufacturing the cylindrical battery case. In addition, corrosion characteristics according to the surface roughness are improved.