PURPOSE: To obtain a core having very low noise in the state of excitation by displaying the maximum distinctive feature of an extra high silicon-content electromagnetic steel plate containing Si of 6.5% or thereabout and having a small magnetostriction.
CONSTITUTION: A core is formed by laminating or winding an extra high silicon- content electromagnetic steel plate (4.9 to 7.1% Si) having the insulation coating of surface roughness of Rmax 3.5μm or higher, an impregnating agent, which performs an additional function as a bonding agent, is inserted between the above-mentioned plates, and a laminated core or a wound core is formed. As the magnetostriction of the used steel plate is small and the vibration of the steel plate is low, the vibration can be absorbed even when the amount of insertion (thin in thickness) is relatively small, and the core having low noise almost to the background noise can be obtained.
YAMASHITA SATOSHI
TANAKA OSAMU
KADOWAKI NOBUO
