ADDITIVE MANUFACTURING APPARATUS AND ADDITIVE MANUFACTURING METHOD
FIG12 is a diagram for explaining the type L3 laser beam illustrated in FIG9
FIG12 is a diagram for explaining the type L3 laser beam 20 illustrated in FIG9. In general, the diameter d of the laser beam 20 at the focus position located at a focal length ff from a light source is determined by specification parameters of an optical lens provided in the irradiation unit. It is desirable to measure in advance the diameter LD of the laser beam 20 at a distance Δf from the focus position. Assuming that the diameter LD is a diameter at which 86.5% of the beam intensity is focused, the diameter LD is roughly calculated by the formula LD=2×Δf×θf. Assuming that the diameter LD is a diameter at which 100% of the beam intensity is focused, the diameter LD is roughly calculated by the formula LD=2×(2×Δf×θf). θf is a maximum angle defined by a light flux and an optical axis X of the laser beam 20.
diagram
23
spreading portion
2
substrate
20
laser beam
['1. An additive manufacturing apparatus (1) for building a deposit on a substrate (2), the apparatus comprising: a feeding unit (6, 8) to feed a build material (7) to a feeding position; an irradiation unit (10, 11, 12) to irradiate the feeding position with a laser beam that melts the build material; a control unit (3) to perform control for building the deposit by stacking beads formed by movement of the feeding position with respect to the substrate and melting of the build material; and an arithmetic unit (4) to execute an arithmetic process of computing parameters for the control unit to perform the control, wherein the beads include two beads (22-1, 22-2) stacked on each other, the two beads are a first bead (22-1) and a second bead (22-2) stacked on the first bead, the first bead being formed earlier than the second bead, the feeding position being a first position (C1) in formation of the first bead, the feeding positon being a second position (C2) in formation of the second bead,  characterized in that  the arithmetic unit calculates an interval (KS) between the first position and the second position in a set direction on a basis of a width (BW) of the first bead and a diameter (LD) of the laser beam, the set direction being a direction of the width of the first bead, and the control unit performs control for setting the second position to a position shifted from the first position in the set direction by the interval, so as to allow a part of the second bead to protrude from the first bead in the set direction.']