Adhesive-Coated Laminated Core Bonding With Low Heat and Pressure
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Solution Overview
Problem
Existing methods for manufacturing laminated cores in motors face challenges in productivity due to high-temperature heating and cooling requirements, which hinder automation and increase equipment size, leading to decreased production efficiency.
Innovation Solution
A laminated core manufacturing method involving the use of adhesive insulating coatings with a lamination direction tensile strength of 20 MPa or more, achieved through low-pressure bonding at 60° C. to 200° C. and 3.0 MPa or less, allowing for efficient stacking and integration without high-temperature heating, followed by a take-out step to simplify the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-temperature heating is used to bond electrical steel sheets, then adhesive bond strength is improved, but cooling time increases and productivity decreases
Solution Approach 1:
The invention changes the bonding parameters by using low-temperature heating (60°C to 200°C) combined with low pressure (3.0 MPa or less) instead of conventional high-temperature heating. This parameter change allows the adhesive to achieve sufficient bond strength without requiring extended cooling periods, thereby improving productivity while maintaining bond quality
Solution Approach 2:
The invention uses a specifically designed adhesive composition that combines thermoplastic resin and thermosetting resin in specific proportions (thermoplastic resin: 10-70 mass%, thermosetting resin: 30-90 mass%). This composite adhesive system enables bonding at lower temperatures while achieving the required bond strength, resolving the contradiction between bond strength and cooling time
2Loss of time
If rapid cooling is applied to the stacked body, then cooling time is reduced, but large-scale cooling mechanism is required increasing apparatus size
Solution Approach 1:
By changing the bonding temperature parameter to low temperature (60°C to 200°C), the invention eliminates the need for rapid cooling. The stacked body can be naturally cooled or cooled at a normal rate without requiring large-scale cooling mechanisms, thus reducing apparatus size while still achieving short cooling times
3Device complexity
If low pressure is used during bonding, then apparatus size is reduced, but bonding effectiveness may be compromised
Solution Approach 1:
The composite adhesive system (thermoplastic resin + thermosetting resin) compensates for the low pressure condition. The thermoplastic resin provides initial bonding under low pressure, while the thermosetting resin cures to provide final bond strength, ensuring bonding effectiveness is maintained even at 3.0 MPa or less
Solution Approach 2:
The invention changes the pressure parameter to low pressure (3.0 MPa or less) while compensating through extended holding time and optimized temperature profile. This parameter change allows using smaller bonding apparatus while maintaining bonding effectiveness through process optimization
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 enables high-production efficiency by reducing the need for large cooling mechanisms and simplifying the manufacturing apparatus, facilitating automation and compact design.
Implementation Method 1
adjacent electrical steel sheets are bonded to each other by heating, at a high temperature, a stacked body obtained by applying a high pressure to a plurality of electrical steel sheets
Implementation Method 2
heating the plurality of electrical steel sheets in the die to a surface temperature of 60° C. or more and 200° C. or less while the plurality of electrical steel sheets in the die are pressurized at 3.0 MPa or less and bonding the plurality of electrical steel sheets adjacent to each other
Data Source
AI summary
A laminated core 10 includes electrical steel sheets 1 and adhesive insulating coatings 2 alternately stacked and has a lamination direction D tensile strength of adhesive bond of 20 MPa or more measured under a 25° C. condition after a complete reaction of each adhesive insulating coating 2. A method for manufacturing a laminated core 10 includes a punching step of punching an electrical steel sheet coated with an adhesive insulating coating 2 to form an electrical steel sheet 1, an accommodating step of stacking and accommodating electrical steel sheets 1 in a die after the punching step, a low-pressure bonding step of heating the electrical steel sheets 1 in the die at a surface temperature of 60° C. or more and 200° C. or less and bonding the adjacent electrical steel sheets 1 by pressurization at 3.0 MPa or less to form a laminated core 10, and a take-out step of taking out the laminated core 10 from the die after the low-pressure bonding step.