Showa Denko K.k.

Mitsubishi Electric Corporation

Tdk Corporation

Other

Showda Denko K.k.

Shiro Sasaki

Hiroshi Hasegawa

Yoichi Hirose

Koichi Yajima

Shinya Fujito

Kazunari Morita

Hiroshi Ukai

Uremu Hosono

Kenichiro Nakajima

Masahide Utsunomiya

Kazuya Ueno

Shinichi Osawa

Masaaki Yui

A power-supply control device includes a high-frequency component detecting unit, a machining voltage level detecting device, a no-load time detecting device, and a pulse control device. The high-frequency component detecting unit detects a high-frequency component of discharge voltage at a machining gap. The machining voltage level detecting device detects a discharge voltage level at the machining gap. The no-load time detecting device detects delay time of discharge of the discharge voltage at the machining gap. The high-frequency component is compared with a reference value to obtain a first comparison result. The discharge voltage level is compared with a reference level to obtain a second comparison result. The pulse control device controls pulse off time based on the first comparison result and the detected delay time, and cuts off a discharge pulse based on the second comparison result.

Power-supply control device for electrical discharge machining apparatus

A power-supply control device includes a high-frequency component detecting unit, a machining voltage level detecting device, and a pulse control device. The high-frequency component detecting unit detects a high-frequency component of discharge voltage at a machining gap. The machining voltage level detecting device detects a discharge voltage level at the machining gap. The high-frequency component is compared with a reference high-frequency component to obtain a first comparison result. The discharge voltage level is compared with a reference voltage level to obtain a second comparison result. The pulse control device controls pulse off time based on the first comparison result, and cuts off a discharge pulse based on the second comparison result.

Power supply-control device for electrical discharge machining apparatus

An apparatus for producing an alloy, including: a casting device which casts a molten alloy using the strip cast method; a crushing device which crushes the cast alloy after casting; and a heating device which keeps the thin laminas of the cast alloy after crushing at a predetermined temperature or which heats the thin laminas of the cast alloy after crushing, wherein the heating device is equipped with a container and a heater.

Apparatus for producing alloy and rare earth element alloy

An R-T-B type alloy (wherein R is at least one member selected from rare earth elements, T is a transition metal including Fe, and B includes boron) which is a raw material for use in a rare earth-based permanent magnet, wherein the volume percentage of the region containing an RTphase having an average grain diameter of 3 &#x3bc;m or less in the short axis direction is from 0.5 to 10%.

R-T-B type alloy, production method of R-T-B type alloy flake, fine powder for R-T-B type rare earth permanent magnet, and R-T-B type rare earth permanent magnet

The present invention is an alloy lump for R-T-B type sintered magnets, including an RTB columnar crystal and an R-rich phase (in which R is at least one rare earth element including Y, T is Fe or Fe with at least one transition metal element except for Fe, and B is boron or boron with carbon), in which in the as-cast state, R-rich phases nearly in the line-like or rod-like shape (the width direction of the line or rod is a short axis direction) are dispersed in the cross section, and the area percentage of the region where RTB columnar crystal grains have a length of 500 &#x3bc;m or more in the long axis direction and a length of 50 &#x3bc;m or more in the short axis direction is 10% or more of the entire alloy.

Alloy lump for R-T-B type sintered magnet, producing method thereof, and magnet

Disclosed is a rare earth magnet in the R&#x2014;T&#x2014;B (rare earth element-transition metal-boron) system that is made from an improved composition and properties of main phase alloy in the R&#x2014;T&#x2014;B system containing Pr and a boundary alloy. Disclosed also is a manufacturing method of the rare earth magnet alloy flake by a strip casting method with improved rotating rollers such that the alloy flake has a specified fine surface roughness and has a small and regulated amount of fine R-rich phase regions. Consequently, the alloy flake for the rare earth magnet does not containing &#x3b1;-Fe and has a homogeneous morphology so that the rare earth magnet formed by sintering or bonding the alloy flakes exhibits excellent magnetic properties.

Alloy flake for rare earth magnet, production method thereof, alloy powder for rare earth sintered magnet, rare earth sintered magnet, alloy powder for bonded magnet and bonded magnet

Disclosed is a rare earth magnet in the R-T-B (rare earth element-transition metal-boron) system that is made from an improved composition and properties of main phase alloy in the R-T-B system containing Pr and a boundary alloy. Disclosed also is a manufacturing method of the rare earth magnet alloy flake by a strip casting method with improved rotating rollers such that the alloy flake has a specified fine surface roughness and has a small and regulated amount of fine R-rich phase regions. Consequently, the alloy flake for the rare earth magnet does not containing &#x3b1;-Fe and has a homogeneous morphology so that the rare earth magnet formed by sintering or bonding the alloy flakes exhibits excellent magnetic properties.

An alloy used for the production of a rare-earth magnet alloy, particularly the boundary-phase alloy in the two-alloy method is provided to improve the crushability. The Alloy consists of (a) from 35 to 60% of Nd, Dy and/or Pr, and the balance being Fe, or (b) from 35 to 60% of Nd, Dy and/or Pr, and at least one element selected from the group consisting of 35% by weight or less of Co, 4% by weight or less of Cu, 3% by weight or less of Al and 3% by weight or less of Ga, and the balance being Fe. The volume fraction of R,Fe,phase (Fe may be replaced with Cu, Co, Al or Ga) is 25% or more in the alloy and the average size of an R,Fe,phase is 20 &mgr;m or less. The alloy can be produced by a centrifugal casting at an average accumulating rate of melt at 0.1 cm/second or less.

Alloy used for production of a rare-earth magnet and method for producing the same

An alloy used for the production of a rare-earth magnet alloy, particularly the boundary-phase alloy in the two-alloy method is provided to improve the crushability. The alloy consists of (a) from 35 to 60% of Nd, Dy and/or Pr, 1% or less of B, and the balance being Fe, or (b) from 35 to 60% of Nd, Dy and/or Pr, 1% or less of B, and at least one element selected from the group consisting of 35% by weight or less of Co, 4% by weight or less of Cu, 3% by weight or less of Al and 3% by weight or less of Ga, and the balance being Fe. The total volume fraction of R.sub.2 Fe.sub.17 and R.sub.2 Fe.sub.14 B phases (Fe may be replaced with Cu, Co, Al or Ga) is 25% or more in the alloy. The average size of each of the R.sub.2 Fe.sub.17 and R.sub.2 Fe.sub.14 B phases is 20 .mu.m or less. The alloy can be produced by a centrifugal casting at an average accumulating rate of melt at 0.1 cm/second or less.

Alloy used for production of a rare-earth magnet and method for

The magnetic properties of rare earth magnet are improved by means of forming a novel structure of the cast alloy used for the production of a rare earth magnet, which contains from 27 to 34% by weight of at least one rare earth element (R) including yttrium, from 0.7 to 1.4% by weight of boron, and the balance being essentially iron and, occasionally any other transition element, and comprises an R.sub.2 T.sub.14 B phase, an R-rich phase and optionally at least one ternary phase except for the R.sub.2 T.sub.14 B phase and the R-rich phase. The novel structure is that the volume fraction (V) in percentage of said R.sub.2 T.sub.14 B phase and said at least one ternary phase is more than 138-1.6r (with the proviso that r is the content of R), the average grain size of the R.sub.2 T.sub.14 B phases is from 10 to 100 .mu.m and, further, the average spacing between the adjacent R-rich phases is from 3 to 15 .mu.m. The novel structure can be formed by by means of feeding alloy melt onto a rotary casting roll, cooling in a temperature range of from melting point to 1000.degree. C. at a cooling rate of 300.degree. C. per second or more, and further cooling in a temperature range of from 800 to 600.degree. C. at a cooling rate of 1.degree. C./second or less.

Method for producing cast alloy and magnet

An alloy used for the production of a rare-earth magnet alloy, particularly the boundary-phase alloy in the two-alloy method is provided to improve the crushability. The Alloy consists of (a) from 35 to 60% of Nd, Dy and/or Pr, and the balance being Fe, or (b) from 35 to 60% of Nd, Dy and/or Pr, and at least one element selected from the group consisting of 35% by weight or less of Co, 4% by weight or less of Cu, 3% by weight or less of Al and 3% by weight or less of Ga, and the balance being Fe. The volume fraction of R.sub.2 Fe.sub.17 phase (Fe may be replaced with Cu, Co, Al or Ga) is 25% or more in the alloy and the average size of an R.sub.2 Fe.sub.17 phase is 20 .mu.m or less. The alloy can be produced by a centrifugal casting at an average accumulating rate of melt at 0.1 cm/second or less.

The magnetic properties of rare earth magnet are improved by means of forming a novel structure of the cast alloy used for the production of a rare earth magnet, which contains from 27 to 34% by weight of at least one rare earth element (R) including yttrium, from 07 to 1.4% by weight of boron, and the balance being essentially iron and, occasionally any other transition element, and comprises an R.sub.2 T.sub.14 B phase, an R-rich phase and optionally at least one ternary phase except for the R.sub.2 T.sub.14 B phase and the R-rich phase. The novel structure is that the volume fraction (V) in percentage of said R.sub.2 T.sub.14 B phase and said at least one ternary phase is more than 138-1.6r (with the proviso that r is the content of R), the average grain size of the R.sub.2 T.sub.14 B phases is from 10 to 100 .mu.m and, further, the average spacing between the adjacent R-rich phases is from 3 to 15 .mu.m. The novel structure can be formed by by means of feeding alloy melt onto a rotary casting roll, cooling in a temperature range of from melting point to 1000.degree. C. at a cooling rate of 300.degree. C. per second or more, and further cooling in a temperature range of from 800 to 600.degree. C. at a cooling rate of 1.degree. C./second or less.

Cast alloy used for production of rare earth magnet and method for

The segregation in the hydrogen-absorbing alloy is decreased by a centrifugal casting which is devised in the present invention so that: a melt fed to the bottom portion of a cylindrical rotary mold solidifies during one rotation of the mold; and, the average depositing speed of melt is from approximately 0.005 to 0.1 cm/second.

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Hanno, Japan

Shiro Sasaki