To reduce the burn through, thermal strain, etc., of a work during beam irradiation by irradiating the work with high energy density beams while supplying an austenite producing element, simultaneously moving the work in its axial direction while being rotated and decreasing the irradiation energy in accordance with the elapse time after irradiation start or the axial direction moving quantity of the work.
By irradiating the work with high energy density beams while supplying an austenite producing element, the prescribed portion of a cylindrical work made of a high magnetic body is modified to a low magnetic body or a non-magnetic body. By this method, by irradiating the work with high energy density beams and moving the work in its axial direction while being rotated, irradiation energy is decreased in accordance with the elapse time after irradiation start or the axial direction moving quantity of the work. This decrease amount is canceled by a energy rise amount due to heat transfer between the insides of the work, as a result, the energy rising of a portion during irradiation is suppressed.
KAWAMURA GOUKIYO
HACHISUGA JOJI
Next Patent: LASER BEAM MACHINING METHOD AND ITS DEVICE