1. Field of the Invention
The present invention relates to an optical modeling apparatus that forms a resin model of a desired shape by exposing a light-curable resin such as an ultraviolet-curable resin or the like to light to form a hardened layer, then stacking the hardened layers to form the model.
2. Description of the Related Art
In recent years, a technique called rapid prototyping has become a focus of attention in many manufacturing environments. Rapid prototyping uses three-dimensional shape data that is input from a CAD device to create a three-dimensional model of a target shape without doing any machining or the like.
Methods that are known as rapid prototyping techniques include optical modeling that uses an ultraviolet-curable resin, fused deposition modeling (FDM), in which a thermoplastic resin is extruded and the extruded thermoplastic resin is layered, selective laser sintering (SLS), in which a powder is fused, bonded, and layered, laminated object manufacturing (LOM), in which thin paper films are layered, the ink jet method, in which a powder and an effective catalyst are discharged and layered, and the like.
Known three-dimensional modeling methods form a model of a desired three-dimensional shape through the process flow described below. Specifically, the first step is to use a computer or the like to input and design a target three-dimensional shape (three-dimensional shape data) created by a CAD device that is a three-dimensional design system.
Next, the CAD data that is input is converted to specified three-dimensional shape data in the STL format or the like. The orientation in which the model is positioned (upright, inverted, sideways, or the like) and the layering direction are determined. The model is then sliced into cross sections with a thickness of approximately 0.1 to 0.2 millimeters in the layering direction, and cross section data is created for each layer.
A three-dimensional model can then be produced, based on the cross section data for each layer, by changing a property of a material such as a liquid light-curable resin, a powdered resin, a metal powder, a wax, or the like, one layer at a time, starting with the lowermost layer, and building up the layers.
Specifically, using the case of the liquid light-curable resin as an example, first, a hardened layer of a specified thickness that becomes the first layer is formed on a moving platform that moves in a direction perpendicular to the surface of the liquid. Next, after the moving platform is moved downward, another hardened layer of a specified thickness is formed on top of the first hardened layer. Additional hardened layers are formed successively in the layering direction, with each nth hardened layer being formed on top of the (n−1)th hardened layer such that the three-dimensional model is produced.
A modeling apparatus that produces a three-dimensional model by a three-dimensional modeling method like that described above can easily produce a three-dimensional shape that has a free-form surface or a complex structure that is difficult to produce by cutting in a three-dimensional modeling method that uses machining. Moreover, the modeling apparatus can produce the desired three-dimensional shape (model) by a completely automated process that does not generate tool wear, noise, vibration, cutting debris, and the like, as is necessary with machining.
In order for this sort of useful three-dimensional modeling technology to be applied in a wide variety of fields, for example, in the manufacture of high-resolution resin moldings with external dimensions measuring from several millimeters to several centimeters and degrees of precision in the range of several microns, modeling with still higher resolution and speed is desirable.