Wound Core Bending With Tensile Stress for Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the production of Unicore wound cores, the plastic deformation strain introduced during bending leads to increased friction between overlapping steel sheets, resulting in noise caused by vibration during excitation.
Innovation Solution
The wound core is produced by stacking grain-oriented electrical steel sheets that have been individually bent while applying tensile stress in the longitudinal direction, ensuring a specific ratio of roughness curve element heights between bent and planar portions, thereby reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If steel sheets are bent to form a wound core (Unicore method), then the processing strain is concentrated only in the bent portion and strain relief annealing can be omitted, but the surface shape of the bent portion becomes rough and the frictional force between overlapping steel sheets increases causing noise
Solution Approach 1:
The patent applies tensile stress to the steel sheet in the longitudinal direction during bending to change the physical state of the material. This parameter change (applying tensile stress) modifies the surface roughness of the bent portion, reducing it to minimize frictional force and noise while maintaining the bending shape.
Solution Approach 2:
The patent applies tensile stress to the steel sheet before and during the bending process to prevent excessive roughness formation. By performing this preliminary action (applying tensile stress), the surface roughness is controlled in advance, reducing the frictional force between overlapping sheets and the resulting noise.
2Manufacturing precision
If steel sheets are bent with a small radius of curvature to form corner portions, then the shape of the iron core is maintained precisely, but the surface roughness of the bent portion increases and frictional force between steel sheets increases
Solution Approach 1:
The patent applies tensile stress to the steel sheet during bending to change the material's physical state. This parameter change reduces the surface roughness of the bent portion even when bending with a small radius of curvature, thereby maintaining manufacturing precision while reducing frictional force and noise.
Solution Approach 2:
The patent converts the potentially harmful effect of bending (which causes roughness and noise) into a beneficial outcome by applying tensile stress during bending. This transforms the bending process into one that maintains precision while reducing surface roughness and frictional force between overlapping sheets.
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 the roughness of the bent portions, decreases the frictional force between overlapping steel sheets, and subsequently minimizes noise caused by vibration during excitation.
Implementation Method 1
the range of plastic deformation strain (processing strain) introduced according to bending of a steel sheet
Implementation Method 2
when bending is performed while tensile stress is applied to the entire end surface (C cross section) of the steel sheet to be bent in the longitudinal (rolling) direction (L direction)
Implementation Method 3
the frictional force between the steel sheets that overlap each other increases
Implementation Method 4
stacking grain-oriented electrical steel sheets in layers and assembling into a wound shape
Data Source
Figure 1
Figure 2
Figure 3
AI summary
This wound core (10) is a wound core (10) including a portion in which grain-oriented electrical steel sheets (1) in which planar portions (4) and bent portions (5) are alternately continuous in a longitudinal direction are stacked in a sheet thickness direction and formed by stacking the grain-oriented electrical steel sheets (1) that have been individually bent in layers and assembled into a wound shape, wherein, when an average height of a roughness curve element in a width direction intersecting the longitudinal direction forming a surface of the bent portion (5) of the grain-oriented electrical steel sheet (1) is Ra(b) and an average height of a roughness curve element in a width direction forming a surface of the planar portion (4) of the grain-oriented electrical steel sheet (1) is Ra(s), the relationship of 1.00<Ra(b)/Ra(s)≤5.00 is satisfied.