Plastic and nonmetallic article shaping or treating: processes – Stereolithographic shaping from liquid precursor
Patent
1996-10-23
1998-05-19
Tentoni, Leo B.
Plastic and nonmetallic article shaping or treating: processes
Stereolithographic shaping from liquid precursor
2504921, 2505031, 250504R, 2505051, 264 401, 264308, 264497, 356121, 359223, 359264, 425135, 4251744, B29C 3508, B29C 4102
Patent
active
057531714
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to methods and apparatus for producing a three-dimensional object by applying subsequent layers of a material that can be solidified by electromagnet radiation and irradiating a focussed beam to places corresponding to the object.
BACKGROUND OF THE INVENTION
An apparatus and a method of this kind is known as stereolithography and can be carried out, as described for example in EP-A-0 171 069, by layerwise solidification of a liquid, photopolymerizeable material using a focused laser beam. This method can also be carried out by sintering powder using the laser beam (see EP-A-0 287 657). In all such cases there is the problem that it is not possible to increase arbitrarily the production speed because a scan speed of the laser beam which depends on the type of the laser and on the material to be solidified cannot be exceeded with a predetermined focusing degree of the laser beam. Furthermore, a possible disadjustment of the laser beam cannot be detected (see EP-A-0 287 657). In all cases one faces the problem that a disadjustment of the beam or deterioration of the beam quality occurs due to shocks, aging of the laser or other effects and therefore the manufacturing quality is deteriorated.
WO 88/02677 discloses a method and apparatus for producing a three-dimensional object by applying subsequent layers of a material that can be solidified by electromagnet radiation and irradiating a focussed beam to places corresponding to the object.
The EP 0 375 097 A2 discloses an apparatus comprising a light source with deflection mirrors and a single position detector which is moved automatically to grid points of a working surface. At the respective grid points the instructions to the deflection mirrors necessary to direct the beam of the light source to the grid points are stored. This enables a calibration of the deflection mirrors. There is further known a stereolithographic apparatus comprising a resin tank which has two sensors for sensing the intensity profile of the beam mounted laterally of the resin tank.
It is therefore the object of the invention to improve the speed and the accuracy of the production of the object and to guarantee a constant quality in the production of the object. Furthermore, an efficient operation even using pulsated lasers should be possible.
SUMMARY OF THE INVENTION
In accord with the present invention, the above object is achieved by a method and apparatus for producing a three-dimensional object by applying subsequent layers of a material that can be solidified by electromagnet radiation and irradiating a focussed beam to places corresponding to the three-dimensional object.
According to the invention the beam used for solidification is measured preferably at a plurality of points of the layer as close as possible to the surface of the material layer, i.e. immediately before striking the material, and compared with reference data. This makes it possible to detect, indicate and, if necessary, correct a possible dusting or disadjustment of the optical system, a defect of the optical or electronical components for adjusting the beam or a beam change due to aging effects.
According to the invention the focusing of the beam used for solidification can be changed and measured so that the best focusing degree and alignment of the beam regarding production speed and accuracy can be adjusted according to the region of the layers to be solidified, the type of the laser and the material. Furthermore, a possible dusting or disadjustment of the optical system, a defect of the optical or electronic components for adjusting the beam and a change of the beam due to aging effects can be detected, indicated and corrected, if necessary. Embodiments of the invention will now be described with reference to the figures. In the figures:
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematical representation of the inventive apparatus;
FIG. 2 shows the concept of changing the beam focus;
FIG. 3 shows the varying focus of the beam according to the
REFERENCES:
patent: 5014207 (1991-05-01), Lawton
patent: 5151813 (1992-09-01), Yamamoto et al.
Lexikon der Optik, H. Haferkorn, Leipzig, 1988, pp. 210, 291 (No Translation).
Systems and Computers in Japan, vol. 20, No. 3, Mar. 1989, pp. 58-66, XP 000071510, Takashi Nakai, et al., "Fabrication of Three-Dimensional Objects Using Laser Lithography", translated from Denshi John Tsushin Gakkai Ronbunshi, vol. 71-D, No. 2, Feb. 1988 pp. 416-423.
Patent Abstracts of Japan, M-991, 1990, vol. 14, No. 300, JP 2-95829.
Langer Hans J.
Reichle Johannes
Serbin Jurgen
EOS GmbH Electro Optical Systems
Neuner George W.
Tentoni Leo B.
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