Laminated Core Bonding Sequence to Cut Residual Stress and Iron Loss
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Solution Overview
Problem
Existing methods for producing laminated cores result in compressive residual stress and increased iron loss due to concurrent pressurization and heating of iron core sheets.
Innovation Solution
A production method and apparatus that involves cutting core sheets from a steel strip with a thermosetting adhesive layer, pressurizing them laterally at a temperature below the adhesive's softening point, and then heating them to adhere and fix them together, using a production apparatus with separate holding and heating parts to control stress and iron loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pressurization and heating of iron core sheets occur concurrently, then production efficiency is improved, but compressive residual stress is generated and iron loss increases
Solution Approach 1:
The patent divides the simultaneous pressurization and heating process into two separate sequential processes: first pressurization at room temperature, then heating at constant volume. This segmentation eliminates the harmful compressive residual stress while maintaining production efficiency, as each process is optimized independently without interfering with the other.
Solution Approach 2:
The patent applies preliminary pressurization to the iron core sheets at room temperature before heating. This preliminary action ensures proper alignment and contact between sheets, and prevents adhesive overflow during subsequent heating, thereby eliminating the need for concurrent pressurization and heating while maintaining production efficiency.
2Loss of time
If concurrent pressurization and heating is used, then manufacturing time is reduced, but iron loss increases due to residual stress
Solution Approach 1:
The manufacturing process is segmented into distinct pressurization and heating stages. The pressurization stage prepares the sheets for bonding, and the heating stage cures the adhesive without generating harmful residual stress. This segmentation eliminates iron loss while the overall process remains efficient due to optimized timing of each stage.
3Strength
If thermosetting adhesive is used for bonding, then bond strength is improved, but adhesive overflow occurs during heating
Solution Approach 1:
The patent applies preliminary pressurization at room temperature before heating to ensure proper alignment and contact between iron core sheets. This preliminary action prevents adhesive overflow during subsequent heating by establishing correct positioning, while still allowing the thermosetting adhesive to achieve full bond strength during the heating phase.
Solution Approach 2:
The patent uses periodic action by applying pressurization only during the room temperature alignment phase, then removing it before heating. This periodic application of pressure ensures proper sheet alignment without causing adhesive overflow during the heating phase, while maintaining strong bonds through the thermosetting adhesive.
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 produces laminated cores with an iron loss degradation rate of 10% or less by reducing compressive residual stress and maintaining low iron loss.
Implementation Method 1
the heating part heats the plurality of core sheets held in the second holding part to a temperature higher than or equal to the softening temperature of the adhesive layer
Implementation Method 2
pressurizing an outer peripheral portion of the plurality of core sheets, which has been cut out, laterally by the first holding part
Implementation Method 3
pressurizing the plurality of core sheets downward by the punch
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
A production apparatus 100 includes a punch 12, a blanking die 14, a first holding part 16, a second holding part 18, and a heating part 20. A plurality of core sheets 1a is cut out from a steel strip 1 by the punch 12 and the blanking die 14, an outer peripheral portion of a plurality of core sheets 1a, which has been cut out, is pressurized laterally by the first holding part 16 and the plurality of core sheets 1a is pressurized downward by the punch 12, and the plurality of core sheets 1a pressurized downward by the punch 12 is heated by the heating part 20 while being held in the second holding part 18. The first holding part 16 holds the plurality of core sheets 1a at a temperature lower than a softening temperature of the adhesive layer 11b, and the heating part 20 heats the plurality of core sheets 1a held in the second holding part 18 to a temperature higher than or equal to the softening temperature.