BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a method of producing a three-dimensionally shaped object using so-called selective laser sintering, and to an additive manufacturing apparatus used therefor.

Description of the Related Art

In recent years, so-called 3D printers have been actively developed, and various methods have been attempted. For example, various methods such as fused deposition modeling, stereolithography using photocurable resin, and selective laser sintering are known.

Selective laser sintering is a method of forming a three-dimensionally shaped object by repetitively performing steps of depositing raw material powder of, for example, nylon resin, ceramics, or metal layer by layer and selectively sintering part of a powder layer by irradiating the powder layer with laser light. In recent years, selective laser sintering using metal powder as a raw material has been used as a method of producing a product for which a high mechanical strength or a good thermal conductivity is required.

For example, Japanese Patent Laid-Open No. 2015-96646 proposes a method of producing a three-dimensionally shaped object formed from metal and having gloss on the surface thereof.

In the case where a three-dimensionally shaped object is formed directly on a shaping table of a three-dimensionally shaping apparatus by selective laser sintering, the three-dimensionally shaped object adheres to the shaping table, and it becomes difficult to separate the three-dimensionally shaped object from the shaping table. Therefore, a method of using a detachable plate for the shaping table and forming a three-dimensionally shaped object on the plate is employed.

Even in the case of using the plate, there is a problem that the three-dimensionally shaped object is damaged when separating the three-dimensionally shaped object from the plate if a target three-dimensionally shaped object is directly formed on the plate because part of the three-dimensionally shaped object adheres to the plate. However, if it is attempted to deposit a thick powder layer on the plate and form a three-dimensionally shaped object on the powder layer, a three-dimensionally shaped object having a desired shape cannot be formed because a sintered body is not fixed to the plate and thus moves on the powder layer and is warped due to thermal deformation.

Therefore, a base is formed on the plate by selective laser sintering, and then a three-dimensionally shaped object having a desired shape is formed on the base. In this case, the three-dimensionally shaped object is separated from the base after formation thereof, and, since the base is formed from a hard sintered body having the same quality as the three-dimensionally shaped object, cutting is performed along a cutting line on the base side so as not to damage the three-dimensionally shaped object when cutting off the three-dimensionally shaped object by using a cutting tool such as a wire cutter. When it is attempted to ensure that the damage is prevented at the time of cutting, a large part of the base remains on the three-dimensionally shaped object. Therefore, there arises necessity to perform additional processing such as fine cutting and polishing, which are time-consuming operations, to remove the part of the base adhering to the three-dimensionally shaped object.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, a method of producing a three-dimensionally shaped object includes a step of equipping an additive manufacturing apparatus with a plate, a step of forming a support portion by depositing raw material powder on the plate and radiating light, a step of forming a three-dimensionally shaped object by depositing raw material powder on the support portion and radiating light, and a step of separating the three-dimensionally shaped object from the support portion. In the step of forming the support portion, a low-density support portion and a high-density support portion are formed. The low-density support portion has a lower density than a three-dimensionally shaped portion formed in the step of forming the three-dimensionally shaped object. The high-density support portion has a higher density than the low-density support portion.

According to a second aspect of the present invention, an additive manufacturing apparatus includes an irradiation optical system comprising a light source, a powder deposition device configured to deposit powder of a shaping material, and a controller configured to perform a process of causing the powder deposition device to deposit powder of a shaping material, a process of forming a support portion by causing the irradiation optical system to radiate light, and a process of forming a three-dimensionally shaped portion on the support portion by causing the irradiation optical system to radiate light. In the process of forming the support portion, a low-density support portion and a high-density support portion are formed. The low-density support portion has a lower density than the three-dimensionally shaped portion formed in the process of forming the three-dimensionally shaped portion. The high-density support portion has a higher density than the low-density support portion.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

