Laminated Core Welding Wire for Reduced Core Loss
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Solution Overview
Problem
Existing methods for manufacturing electrical steel sheet laminated cores, such as welding, result in magnetic loss due to mechanical/thermal strain and core loss from short circuits, particularly in large cores used in high-power motors, where reducing welding heat or points is limited by the need for sufficient joining force.
Innovation Solution
A method involving the use of a welding wire with a resistivity of 6.5 × 10^-7 Ωm or greater and a relative permeability of less than 1.02, such as an Fe-Cr-Ni-containing alloy or Ni-containing alloy with a Ni content greater than 25wt%, which has a melting point lower than the electrical steel sheets, to reduce thermal stress and improve magnetic characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding method is used to join electrical steel sheets, then joining force is sufficient, but core loss increases due to thermal strain and short circuits
Solution Approach 1:
The invention changes the electrical resistance parameter of the welding wire to 6.5×10^-7 Ωm or greater, which is higher than conventional welding wires. This parameter change reduces short circuit current between stacked electrical steel sheets during welding, thereby reducing core loss while maintaining sufficient joining force through proper weld metal deposition
Solution Approach 2:
The invention uses a welding wire with specific composite material properties combining high electrical resistance (6.5×10^-7 Ωm or greater) with appropriate melting point characteristics. This composite material approach allows the weld metal to provide both mechanical strength for joining and electrical insulation properties to reduce short circuit losses
2Loss of energy
If amount of input welding heat is reduced, then core loss decreases, but joining force becomes insufficient for large cores
Solution Approach 1:
The invention changes the electrical resistance parameter of the welding wire to 6.5×10^-7 Ωm or greater, which reduces short circuit current and core loss. Simultaneously, the welding process parameters (current, speed, wire feed rate) are optimized to ensure adequate heat input for proper weld metal deposition and solidification, maintaining sufficient joining force even with reduced overall heat input
3Ease of manufacture
If conventional welding wire is used, then welding process is simple, but porous defects occur due to gas permeation during solidification
Solution Approach 1:
The invention changes the melting point parameter of the welding wire to be lower than the electrical steel sheets. This parameter change extends the liquidation time of the weld metal during solidification, allowing gas to escape before the weld metal solidifies completely, thereby preventing porous defects while maintaining a relatively simple 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 reduces core loss and enhances the strength of the laminated core, preventing welding defects like pores and pits, while maintaining sufficient joining force, enabling the use of the laminated core in both small and large products.
Implementation Method 1
thermal stress/strain can be reduced without reducing the joining force of the weld by controlling the rate of input welding heat
Implementation Method 2
thermal stress/strain can be reduced without reducing the joining force of the weld by controlling the rate of input welding heat
Implementation Method 3
a welding wire having a resistivity of 6.5 × 10^-7 Ωm or greater and a melting point lower than that of the electrical steel sheets
Implementation Method 4
the weld has a resistivity of 6.5 × 10^-7 Ωm or greater... controlling the magnetic characteristics of a weld and the resistance of short circuit parts caused by welding
Data Source
Figure 1~2
Figure 3(a)~3(b)
Figure 4(a)~4(d)
AI summary
There are provided a method for manufacturing an electrical steel sheet laminated core having reduced core loss and improved strength, and a laminated core produced by the manufacturing method. The method includes: stacking electrical steel sheets to obtain a lamination; and welding an outer surface of the lamination, wherein during the welding, a welding wire having a resistivity of 6.5 x 10-7 Ωm or greater, a relative permeability of less than 1.02, and a melting point lower than that of the electrical steel sheets is used as a welding material.