Three-dimensional laminating and shaping apparatus and laminating and shaping method

A laminating and shaping method for a three-dimensional structure, performed by a three-dimensional laminating and shaping apparatus including a powder feeder configured to feed a powder layer of an electrically conductive material, an electron beam column configured to output an electron beam and deflect the electron beam toward a front surface of the powder layer, an insulating portion that is in contact with the three-dimensional structure and electrically insulates the three-dimensional structure from a ground potential member, an ammeter connected between the three-dimensional structure and the ground potential member and configured to measure a current value of a current flowing into the ground potential member after passing through the three-dimensional structure, a melting judging unit configured to, based on the current value measured by the ammeter, detect that the powder layer is melted and generate a melted powder form signal, and a deflection controller configured to receive the melted powder form signal and determine a condition of irradiation with the electron beam, the laminating and shaping method comprising:

• by the powder feeder, feeding the powder layer;
• by the electron beam column, irradiating the powder layer with the electron beam;
• by the ammeter, measuring the current value of the current flowing into the ground potential member after passing through the three-dimensional structure;
• by the melting judging unit having a program, generating the melted powder form signal based on a timing at which a difference between a current value of the electron beam irradiating the powder layer and the current value measured by the ammeter becomes less than or equal to a reference value;
• and
• by the deflection controller, setting a condition of the irradiation based on the melted powder form signal.