Power Storage Lid Welding to Prevent Resin Heat Damage
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Solution Overview
Problem
Existing methods for laser welding the opening portion of a case body and the outer circumferential edge portion of a lid in power storage devices often result in a molten portion with an upward bulge, causing reflected light to travel inward and lead to thermal deterioration of the insulation resin member.
Innovation Solution
A method involving a multi-beam laser beam pattern that provides more heat input to the opening portion than the outer circumferential edge portion during welding, with the case body opening positioned below the lid, and incorporating a recessed groove in the lid design to prevent molten metal bulging, ensuring the reflected light does not reach the insulation resin member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intensity of laser beamlet irradiated to the opening portion of the case body is set higher than that of laser beamlet irradiated to the outer circumferential edge portion of the lid, then the reflected light of the laser beam travels outward preventing thermal deterioration of the insulation resin member, but the molten portion forms an upward bulging shape when the case body opening is positioned at a higher side than the lid outer circumferential edge
Solution Approach 1:
The patent inverts the conventional arrangement by positioning the case body opening portion at a lower side than the lid outer circumferential edge portion. This inversion changes the direction of gravitational force acting on the molten metal, causing it to flow downward into the opening portion rather than upward, thereby eliminating the upward bulge while maintaining the protective reflected light effect.
Solution Approach 2:
The patent changes the positional parameter of the case body opening portion relative to the lid outer circumferential edge portion. By setting the opening portion at a lower position, the gravitational potential energy difference drives molten metal flow in the desired direction, preventing upward bulging while preserving the reflected light shielding effect.
2Ease of manufacture
If the case body opening portion is positioned at a higher side than the lid outer circumferential edge portion, then the assembly is easier to manufacture, but the reflected light of the laser beam travels inward causing thermal deterioration of the insulation resin member
Solution Approach 1:
The patent inverts the conventional arrangement by positioning the case body opening portion at a lower side than the lid outer circumferential edge portion. This inversion changes the direction of gravitational force acting on the molten metal, causing it to flow downward into the opening portion rather than upward, thereby eliminating the upward bulge while maintaining the protective reflected light effect.
Solution Approach 2:
The patent converts the harmful effect of gravity (which would cause upward bulging in conventional arrangements) into a beneficial effect. By inverting the position, gravity now aids in directing molten metal flow downward into the opening portion, preventing both upward bulge and reflected light damage to the insulation resin member.
3Shape
If a multi-beam laser beam with higher heat input to the opening portion is used, then the molten portion becomes flat preventing reflected light from reaching the insulation resin member, but the welding process becomes more complex
Solution Approach 1:
The patent changes the heat input parameter distribution across the multi-beam laser system. By allocating higher heat input to beamlets irradiating the opening portion and lower heat input to beamlets irradiating the outer circumferential edge portion, the patent achieves flat molten portion formation without requiring complex mechanical adjustments, simplifying the overall welding process.
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 approach effectively prevents or reduces thermal deterioration of the insulation resin member by ensuring the molten portion is flat and does not reflect light inward, thereby maintaining the integrity of the power storage device.
Implementation Method 1
a multi-beam laser beam of a beamlet pattern that provides more heat input to the unmelted opening portion compared to the unmelted outer circumferential edge portion is irradiated to the unmelted outer circumferential edge portion and the unmelted opening portion to laser-weld the outer circumferential edge portion and the opening portion
Implementation Method 2
a melted-solidified portion formed by a part of the outer circumferential edge portion and a part of the opening portion that are melted together and then solidified
Implementation Method 3
the unmelted opening portion of the case body is placed on a lower side more than a circumferential edge upper surface of an unmelted outer circumferential edge portion of the lid
Data Source
AI summary
A method for manufacturing a power storage device, in which an outer circumferential edge portion of a lid and an opening portion of a case body are welded via a melted-solidified portion, includes: a placing step of placing the lid in an unmelted opening portion of the case body; a welding step of welding the outer circumferential edge portion 36 of the lid 33 and the opening portion of the case body over their entire circumference. In the placing step, the unmelted opening portion of the case body is placed on a lower side more than a circumferential edge upper surface of the unmelted outer circumferential edge portion of the lid. In the welding step, laser welding is performed by irradiating a multi-beam of a beamlet pattern that provides more heat input to the unmelted opening portion compared to the unmelted outer circumferential edge portion.