Nippon Steel Corporation

Masao Yabumoto

Masato Mizokami

Tatsuhiko Sakai

Yoshiyuki Ushigami

Masaki Tanaka

Fumiaki Takahashi

Shuichi Yamazaki

Hideyuki Hamamura

Hisashi Mogi

Masahiro Fujikura

Osamu Akisue

Takahito Mizumura

Tadao Nozawa

Norito Abe

Eisuke Minematsu

Toshihiko Uemura

A wound core is formed by laminating a plurality of bent bodies formed from a grain-oriented electrical steel sheet having a coating containing phosphorus formed on a surface, in a sheet thickness direction of the grain-oriented electrical steel sheet, in which the bent body is formed in a rectangular shape by having four flat portions and four corner portions adjacent to the flat portions, the corner portion has a bent region having a total bending angle of approximately 90&#xb0; in a side view, the number of deformation twins present in the bent region in the side view is five or less per 1 mm of a length of a center line in the bent region in the sheet thickness direction, and the amount of phosphorus eluted from the corner portion in a case of being boiled in water for 30 minutes is 6.0 mg or less per 1 mof a surface area of the corner portion.

Wound core and manufacturing method thereof

There is provided a method for manufacturing a grain-oriented electromagnetic steel sheet whose iron losses are reduced by laser beam irradiation, capable of improving the iron losses in both the L-direction and the C-direction while easily ensuring high productivity. The method for manufacturing a grain-oriented electromagnetic steel sheet reduces iron losses by scanning and irradiating a grain-oriented electromagnetic steel sheet with a continuous-wave laser beam condensed into a circular or elliptical shape at constant intervals in a direction substantially perpendicular to a rolling direction of the grain-oriented electromagnetic steel sheet, wherein when an average irradiation energy density Ua is defined as Ua=P/(Vc&#xd7;PL) (mJ/mm), where P (W) is average power of the laser beam, Vc (m/s) is a beam scanning velocity, and PL (mm) is an irradiation interval in a rolling direction, PL and Ua are in the following ranges: 1.0 mm&#x2266;PL&#x2266;3.0 mm, 0.8 mJ/mm&#x2266;Ua&#x2266;2.0 mJ/mm.

Method for manufacturing grain-oriented electromagnetic steel sheet whose magnetic domains are controlled by laser beam irradiation

The present invention provides an electrical steel sheet core for a low-noise transformer capable of effectively lowering noise by suppressing vibration perpendicular to the surfaces of the steel sheets and reducing vibration, and relates to an electrical steel sheet for a low-noise transformer characterized by randomly inserting viscoelastic layers with both viscosity and elasticity into the gaps of the steel sheet lamination layers, and a low-noise transformer formed by using said electrical steel sheet.

Electrical steel sheet for low-noise transformer and low-noise transformer

The present invention provides a wound core having a low core loss and not susceptible to a disappearance of the core loss lowering effect due to a magnetic domain refining even when stress-relief annealing is conducted after fabrication of a steel strip into a wound core, through a process which comprises, fabricating a very thin silicon steel strip comprising by 6.5% weight or less of silicon with the balance consisting essentially of iron and having a sheet thickness of 100 .mu.m or less and a magnetic flux density (B.sub.8 value) of 1.80T or more into a wound core, subjecting the wound core to stress-relief annealing, unwinding the very thin silicon steel strip from the core, introducing into the very thin silicon steel strip a linear or dotted local strain in a direction at an angle of 45.degree. to 90.degree. to the rolling direction of the thin strip, and rewinding the thin strip onto the core.

Process for preparing wound core having low core loss

Growing community of inventors

Tokyo, Japan

Masao Yabumoto