Plastic and nonmetallic article shaping or treating: processes – Direct application of electrical or wave energy to work – Using laser sintering of particulate material to build...
Reexamination Certificate
2000-06-16
2004-01-27
Staicovici, Stefan (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of electrical or wave energy to work
Using laser sintering of particulate material to build...
C264S257000, C264S258000, C264S308000, C264S482000, C156S272800, C156S273500, C156S275500, C156S298000, C156S303100, C156S379800
Reexamination Certificate
active
06682688
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a three-dimensionally shaped object in which the shaped object is obtained by successively laminating hardened layers of hardened powder material.
2. Description of the Related Art
A method as shown in
FIGS. 50A and 50B
of manufacturing a three-dimensional object by successively laminating hardened layers
102
of hardened powder material
101
is well known. This is disclosed in Japanese Patent No. 2620353 as a “Method of manufacturing parts by selective sintering.” According to this Patent, the powder material
101
, which is an organic material such as a resin or an inorganic material such as a metal, is first accumulated and then hardened to form a hardened layer
102
by irradiating thereon an optical beam (laser beam
112
) such as a laser or directional energy beam. The hardened layers
102
thus obtained are laminated one above another to form a three-dimensional object.
In this case, as shown in
FIG. 50A
, the powder material
101
is supplied from a hopper
129
to an enclosing structure
130
, and as shown in
FIG. 50B
, a laser beam
112
is selectively irradiated onto a predetermined position. This is repeatedly carried out to form a laminate of the hardened layers
102
. The laser beam
112
is emitted from a laser head
131
and is operated in such a way that the direction of its path is altered by a scanning system
133
including a prism
132
so that a predetermined position on the powder material
101
of the uppermost layer within the enclosing structure
130
is selectively irradiated. Accordingly, a complex shaped object can be manufactured comparatively easily.
In the above-described prior art, however, the packing density of the powder material
101
is low and, hence, the density after irradiation and hardening does not become 100%. For this reason, there are problems in that the strength of the manufactured shaped object is weaker by comparison with the essential mechanical strength of the material. There are additional problems in that although the laser beam
112
must be scanned to form the hardened layers
102
, the shaping time becomes long because the amount of scanning data within the contour lines of the shaped object is large. There are further problems in that, because the powder material
101
contracts when it is hardened, the hardened layers
102
are deformed and a shaped object of satisfactory precision cannot be manufactured.
SUMMARY OF THE INVENTION
The present invention has been developed to overcome the above-described disadvantages.
It is accordingly an objective of the present invention to provide a method of manufacturing a three-dimensional object which is capable of easily manufacturing a shaped object of high strength and high precision, even if the shape thereof is complex.
In accomplishing the above and other objectives, the method according to the present invention is characterized by: (a) filling a powder material around a core so as to form a layer of powder material; (b) selectively irradiating a beam on the layer of powder material to form a hardened layer united with the core, and (c) repeating the steps (a) and (b) to form a plurality of hardened layers around the core.
According to this method, if the core is so formed as to have a high density and a high strength, the shaped object has a high strength as a whole. Moreover, only the powder material in the outer region in the proximity of the core needs to be successively hardened to form a laminated structure, and the amount of scanning data, for the scanning of the beam which affords the hardening at this time, is reduced within the contour lines of the shaped object. As a result, the scanning time is shortened and, even if the shape is complex, the shaping time can be also shortened. In addition, because the amount of powder material to be hardened is reduced, distortion or deformation due to contraction during hardening is prevented and a high precision shaped object can be manufactured.
Furthermore, by lowering the core by a dimension equivalent to the thickness of each hardened layer, the hardened layers are successively laminated around the core. Also, the powder material can be filled easily after each hardening, and the distance setting and the like of the beam to be irradiated thereon is also easy.
The core is made up of a plurality of sheet materials laminated one above another that are united together before the steps (a) and (b), and each of the sheet materials is an organic material or an inorganic material. Because the core is integrated in advance, it can be easily made even if the shaped object has a complicated shape.
Alternatively, each of the plurality of sheet materials is laminated before the step (a). By so doing, there is no need for the sheet materials to be integrally laminated in advance, and the core can be formed simply by successively laminating the sheet materials prior to the formation of the hardened layers. Also, the core forms no obstruction to the filling of the powder material.
Advantageously, each of the plurality of sheet materials has a through-hole, in which the powder material is filled and hardened to unite neighboring sheet materials. In this case in particular, the sheet materials are joined by the hardening of the powder materials filled into the through-holes, so the joining strength between the sheet materials is enhanced and the distortion of the sheet materials due to heat effects during hardening of the powder material is prevented, resulting in a shaped object of higher density and higher precision. Furthermore, the sheet materials can be appropriately positioned with each other without lateral offsetting.
The through hole can be so formed as to extend through all of the plurality of sheet materials. The through- hole may be inclined.
Each sheet material may be coated with a powder material, wherein a beam is irradiated thereon to unite neighboring sheet materials, resulting in a shaped object of high strength.
The powder material may have a melting point lower than that of the sheet materials.
Each sheet material may have an independent area connected thereto via a plurality of connecting portions, which are removed during or after the shaping.
When a box-shaped object is manufactured, the powder material is filled in a space formed at an edge portion of each sheet material.
It is preferred that the plurality of sheet materials be appropriately positioned by at least one positioning member. The positioning member is a movable member driven by a separate device, or is formed on at least one of the plurality of sheet materials. Alternatively, the positioning member is formed by irradiating a beam on a powder material coated on the at least one of the plurality of sheet materials. Again alternatively, the plurality of sheet materials are appropriately positioned by protrusions formed thereon. Each of the plurality of sheet materials may have a positioning piece integrally formed therewith, which is brought into contact with a separate positioning member.
All the sheet materials do not have the same thickness, that is, the plurality of sheet materials may have different thickness. In this case, the thickness of the sheet materials are set to be thick at positions where the inclination of the outer side surface of the core is steep and to be thin at positions where the inclination is gentle. Accordingly, the level difference generated at the edges of the sheet materials can be reduced, making it possible to smoothly finish the surface of the shaped object.
A solidified powder layer may be interposed between neighboring sheet materials. In this case in particular, even if the laminated surface of the sheet materials has a complicated shape, a shaped object having a fine and complicated shape can be easily manufactured by arranging the solidified powder layer in position between the neighboring sheet materials.
The layer of powder material filled around each sheet material may have a tapered upper surface fo
Fuwa Isao
Higashi Yoshikazu
Uchinono Yoshiyuki
Yoshida Norio
Greenblum & Bernstein P.L.C.
Matsushita Electric & Works Ltd.
Staicovici Stefan
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