JPH049661B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to improvements in methods and apparatus for forming three-dimensional objects from a fluid medium, and in particular, for forming three-dimensional objects quickly, reliably, accurately and economically. to be able to do,
This field concerns three-dimensional modeling that applies trigraphy to the production of three-dimensional objects.

[Conventional technology]

When manufacturing parts made of plastic,
First, it is common to first design a part and then painstakingly create a prototype of this part. All of these require considerable time, effort and expense. This design is then reviewed until the design is optimal.
This time-consuming process is often repeated many times. After the design is optimized, the next step is its manufacture. In most production, plastic parts are injection molded. Because the design time and tooling costs are so high, injection plastic parts are usually only practical when produced in large quantities. Other methods such as direct machining, vacuum forming and direct molding can be used to manufacture plastic parts. However, these methods are typically cost effective only for short runs of production, and the parts produced are of inferior quality to injection molded parts.

Recently, very good methods have been developed to create three-dimensional objects in a fluid medium. The fluid medium is selectively stiffened by a beam of radiation selectively focused at predetermined points of intersection within a three-dimensional volume of the fluid medium. Typical devices for forming such three-dimensional objects are U.S. Pat. No. 2,775,785, U.S. Pat.
No. 4078229, No. 4238840, No. 4288861 JP-A-Sho
Publication No. 56-144478, Hideo Kodama, "Automatic creation of three-dimensional shapes as a method for displaying three-dimensional information" (Transactions of the Institute of Electronics and Communication Engineers, VOL. J64-C No. 4, April 1981),
Hideo Kodama，Automatic method for
fabricating a three-dimensional Plastic
model with photo-hardening polymer,
Review of Scientific Instruments, 52(11),
Nov.1981, and Alan J. Herbert, Solid Object
Generation, Journal of Applied Photographic
Engineering VOL8, No. 4, August 1982. All of these devices use various extensive multiple beam schemes to extract synergistic energy at selected points deep within the fluid volume to the exclusion of all other points within the fluid volume. It relies on granting. In this regard, various conventional systems use a pair of electromagnetic radiation beams oriented such that they intersect at specific coordinates. In this case, the various beams may have the same or different wavelengths, or the beams may intersect the same point successively rather than simultaneously. However, in all of these cases, only the intersection points of the beams are energized to an energy level sufficient to accomplish the curing process necessary to form a three-dimensional object within the volume of fluid medium.

(Problems to be Solved by the Invention) Unfortunately, however, such a three-dimensional molding apparatus has many problems in terms of resolution and exposure control. The reduction in radiation intensity as the point of intersection moves deeper into the fluid medium, and the reduction in resolution for imaging the focused spot, naturally result in complex control conditions. absorption,
Diffusion, dispersion, and analytical methods all make it difficult to process economically and reliably deep within a fluid medium. Therefore, it was difficult to form extremely thin layers, and automatic lamination was also difficult.

However, it is important to be able to move quickly and reliably from the design stage to the prototype stage and to final production, especially from computerized design to prototype virtually immediately for such plastic parts. There remains a long-standing need in the field of design and manufacturing for equipment that can be robustly mass-produced economically and automatically.

Therefore, those involved in the development and manufacture of three-dimensional plastic objects, etc. can move from design to prototype to manufacturing while avoiding the complex focusing, alignment and exposure problems of traditional three-dimensional manufacturing equipment. It has been recognized that it would be desirable to further develop a more rapid, reliable, economical and automatic means by which the transfer of data may be carried out quickly. This invention satisfactorily meets all these needs.

[Means and actions for solving problems]

The present invention constructs a three-dimensional object by forming successive adjacent cross-sectional laminates of this object on the surface of a fluid medium that can change its physical state in response to appropriate synergistic energies. Provides new and improved equipment for making. Successive laminates are automatically tightly integrated as they are formed to form the desired three-dimensional object.

By way of example, and not by way of limitation, in the presently preferred embodiment, the invention utilizes the idea of computer-generated graphics in combination with lithography. In other words, in order to apply lithography technology to the manufacture of three-dimensional objects and directly manufacture three-dimensional objects from computer instructions, computer-assisted design (CAD) and computer-assisted design are necessary. Carry out manufacturing (CAM) at the same time. The invention can be used for forming templates and prototypes at the design stage of product development, or as a manufacturing device, or for the formation of purely artistic objects.

Here, "three-dimensional modeling" refers to materials that can be hardened,
For example, a method and apparatus for making objects by "printing" thin layers of infrared curable material on top of each other. A programmed light source that illuminates a surface or layer of liquid that can be cured with UV (ultraviolet) light.
A moving spot beam of UV light is used to form a solid cross section of an object on the surface of a liquid. The object is then moved away from the surface of the liquid by one layer thickness in a programmed manner, after which the next cross-section is formed and adhered to the immediately previous layer to form the object. Continue this process until the entire object is formed.

The method of the invention allows the formation of almost any form of object. Complex shapes are made easier to create by using computer functions to generate program instructions and then send program signals to the stereolithography device.

Of course, particle irradiation (such as an electron beam), spraying of material through a mask, or chemical reaction with an ink jet, or non-ultraviolet radiation
It would not be outside the scope of the invention to practice the invention using other types of suitable synergistic energy on the curable fluid medium, such as radiation.

By way of example, in practicing the invention, a body of fluid medium capable of solidifying in response to a predetermined energy may first be contained in any suitable container to form successive cross-sectional laminates therein. Confining selected working surfaces of the fluid medium such that
Thereafter, synergistic energy of a suitable type, such as spots of ultraviolet light, is applied in a graphic pattern to a specified working surface of the fluid medium to form a thin, solid, discrete layer on this surface. As they are formed, successive adjacent layers, each layer representing an adjacent cross-section of the three-dimensional object to be created, are automatically superimposed on each other to unite the layers and form the desired three-dimensional object. form. In this regard, when the fluid medium is cured and the solid material is formed as a thin laminate on the working surface, a suitable platform to which the first laminate is fixed is moved by any suitable actuating device, typically all It is moved away from the work surface in a programmed manner under the control of a microcomputer or the like. In this way, the solid material initially formed on the working surface is moved away from this surface, and new liquid flows into the position of the working surface. A portion of this new liquid is converted into a solid material by a programmed UV light spot to define a new laminate, and this new laminate is bonded to the material adjacent to it, i.e. the immediately previous laminate. Joined. This process continues until the entire three-dimensional object is formed. After this, the formed object is removed from the container and
The device is ready to create another object identical to the first object, or an entirely new object generated by the computer.

The stereolithography method and apparatus of the present invention has many advantages over methods currently used to create plastic objects. That is, the method of this invention creates a design layout and drawings,
There is no need to create processing drawings and tools. The designer can work directly with the computer and stereolithography equipment and, when satisfied with the design displayed on the computer's output screen, can manufacture the part for direct inspection. If the design has to be modified, this can easily be done through a computer and then another part can be made to confirm that the design changes were correct. If a design calls for several parts with interacting design parameters, the entire design of the parts can be quickly changed and rebuilt, and the entire assembly can be built and tested iteratively if necessary. The method of the present invention is even more useful because it can.

After the design is complete, manufacturing of the part can begin immediately, avoiding weeks or months of turnaround time between design and manufacturing. The final production rate and cost of parts should be similar to current injection molding costs for short run production, and the cost of labor will be much lower than for injection molding. Injection molding is economical only when large numbers of identical parts are required. With no tooling required and very short production set-up times, stereolithography lends itself to short production runs. Similarly, design changes and custom parts are easily obtained using this method. Because the parts are easy to manufacture, stereolithography allows the use of plastic parts in many places where parts of metal or other materials are currently used. Additionally, a plastic model of the object can be made quickly and economically before a decision is made to make parts of expensive metal or other materials.

Therefore, the three-dimensional modeling method and apparatus of the present invention address the long-standing need for a CAD or CAM system that can quickly, reliably, accurately, and economically design and manufacture three-dimensional plastic parts. This is a response to the following.

The above and other objects and advantages of the present invention will become apparent from the detailed description of the drawings below.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.
FIGS. 1 and 2 are flowcharts showing the basic method and apparatus of the present invention for creating a three-dimensional object by stereolithography.

The immobilization of polymers by ultraviolet (UV) irradiation, electron beam visible light, non-visible light irradiation, ink jets or other types of synergistic energy such as reactive chemicals applied through a suitable mask A number of liquid state chemical agents are known that can be induced to transform into plastics. UV
Curable chemicals are currently used as inks in high speed printing, as adhesives in coating processes for paper and other materials, and in other specialty areas.

Three-dimensional modeling is a technology that reproduces graphic objects using various methods. Current examples include photocopying, xerography, and microengraving, such as those used in the manufacture of microelectronic circuits. Computer-generated graphics displayed on a plotter or cathode ray tube are also lithographic forms;
An image is an image of an object encoded by a computer.

Computer-aided design (CAD) and computer-aided manufacturing (CAM) are techniques that apply the power of computers to the design and manufacturing process.
A typical example of CAD is in the field of electronic printed wiring design, where computers and plotters
A typical example of CAM that draws a printed wiring board design is a numerically controlled milling machine, where the computer and milling machine, given the appropriate programming instructions, draw a metal part when the design parameters are given as data input to a computer. Process. CAD and CAM
is also an important and rapidly growing technology.

The main purpose of this invention is to utilize computer-generated graphic ideas in combination with UV-curable plastics to simultaneously execute CAD and CAM to create three-dimensional objects directly from computer instructions. It is. This invention is called three-dimensional modeling, and can be used to form templates and prototypes at the design stage of product development, as a manufacturing device, or as artistic forms.

FIG. 1 broadly explains the three-dimensional modeling method of the present invention. Step 10 in FIG. 1 represents the creation of individual laminates representing the cross-sections of the three-dimensional object to be formed. Step 11, which is typically only performed if step 10 has been performed correctly, combines adjacent laminates formed in succession to form the desired three-dimensional object as programmed in the device. , selectively curing. For this reason, the three-dimensional modeling apparatus of the present invention is capable of handling incoming radiation, electron beams, and other particle irradiation.
A fluid that can change its physical state in response to appropriate synergistic energy, such as a jet or a chemical agent applied by spraying through a mask adjacent to the surface of the fluid. A three-dimensional object is created by creating a cross-sectional pattern of the object to be formed on a selected surface of a medium, such as a UV-curable liquid. Successive adjacent laminates representing successive adjacent cross-sections of the object are automatically formed and integrated to create a graded layered or laminar configuration of the object, and during such forming steps, the fluid medium is A three-dimensional object is formed and pulled from a generally planar or sheet surface.

The method described above is described in more detail in FIG. In FIG. 2, step 12 requires containing a fluid medium capable of solidifying in response to a predetermined reactive energy. Step 13 applies this energy in a graphic pattern to a selected fluid surface to form a thin, solid, discrete layer on that surface. Each layer represents an adjacent cross section of the three-dimensional object being created. It is desirable that each such layer be made as thin as possible while practicing this invention to maximize the resolution and accurate reproduction of the three-dimensional object being formed, as well as to reduce fabrication time. For this reason, an ideal theoretical situation would be such that the object is made with only selected working surfaces of the fluid medium, resulting in an infinite number of laminates, each with a thickness of zero. The hardened depth is only slightly large (e.g. less than 1 mm)
The goal is to have the following. By forming such a thin layer, the accuracy of the formed object can be improved, and it is also possible to form a molded part without a support on the surface. Of course, when this invention is used in practice, each laminate is a thin laminate, but suitable bonding is required when bonding to adjacent laminates to form a cross-section and define other cross-sections of the object being formed. The thickness should be such that it has the properties.

In step 14 of FIG. 2, successive adjacent layers or laminates are superimposed on each other as they are formed to integrate the various layers and form the desired three-dimensional object. In the normal practice of this invention, when the fluid medium is cured and the solid material is formed to form a laminate, the laminate is moved away from the working surface of the fluid medium and the previously formed laminate The next laminate is formed in the new liquid replacing the laminate, so that each successive laminate is superimposed on every other cross-sectional laminate (by the natural adhesive properties of the hardened fluid medium). Become one. For this reason, the process of manufacturing such cross-sectional laminates is repeated many times until the entire three-dimensional object is formed. after that,
The object is removed and the device is ready to produce another object. This object may be the same as the previous object, or it may be made into a completely new object by replacing the program controlling the stereolithography device.

FIGS. 3-8 illustrate various apparatus suitable for carrying out the three-dimensional fabrication method shown in the flowcharts of FIGS. 1 and 2.

As previously mentioned, "stereolithography" is a method and apparatus for making solid objects by "printing" thin layers of curable material, e.g. UV-curable material, one on top of the other in succession. . A programmed, movable spot beam of UV light that illuminates the surface or layer of a UV-curable liquid is used to form a solid cross-section of an object on the surface of the liquid. After this, in a programmed manner, the object is moved away from the surface of the liquid by one layer thickness, forming the next cross section and bonding with the previous layer to define the object. until the whole object is formed.
Continue this process.

The method of the invention allows almost any type of object to be shaped. By using the power of a computer to generate program instructions and send program signals to a stereolithography device, complex shapes can be created more easily.

A three-dimensional modeling apparatus according to a presently preferred embodiment is shown in a side sectional view in FIG. A container 21 is filled with a UV curable liquid 22 or the like, and a selected work surface 23 is defined. A programmable source of ultraviolet radiation 26 produces an ultraviolet spot 2 in the plane of surface 23.
Make 7. By movement of a mirror or other optical or mechanical element (not shown) that is part of the light source 26, the spot 27 can be moved across the surface 23. The position of spot 27 on surface 23 is controlled by a computer or other programming device 28. A movable lifting platform 29 inside the container 21 can be selectively raised and lowered. The position of the platform 29 is controlled by a computer 28. When the apparatus operates, a three-dimensional object 30 is formed by progressively stacking unitary laminates such as 30a, 30b, and 30c.

The surface of the UV curable liquid 22 is maintained at a constant height within the container 21 and exposed to a spot 27 or other suitable type of UV light of sufficient intensity to cure the liquid and convert it into a solid material. reactive energy is transferred across the work surface 23 in a programmed manner. When the liquid 22 hardens to form a solid material, the lifting platform 29, which was initially just below the working surface 23, is lowered from this working surface in a programmed manner by means of a suitable actuator. Ru. In this way, the initially formed solid material comes to be below the surface 23 and the new liquid 22 flows into the surface 23. A portion of this new liquid is converted into a solid material by the programmed UV light spot 27, and this new material is bonded to the underlying material by adhesive. This process continues until the entire three-dimensional object 30 is formed. Object 30 is then removed from container 21 and the device is ready to make another object. Thereafter, another object can be created, or by replacing the program on the computer 28, a new object can be created. The curable liquid 22, such as a UV curable liquid, must have several important properties. (A) It must cure quickly with an available UV light source so that practical object formation times are obtained. (B) Must be adhesive so that successive layers adhere to each other. (C) When the viscosity is low enough and the lifting platform moves the object,
Fresh liquid material must flow quickly to the surface. (D) UV should be absorbed so that the layer formed is reasonably thin. (E) is reasonably soluble in the solvent in the liquid state and reasonably insoluble in the same solvent in the solid state;
After the object is formed, it must be possible to wash the UV-curable liquid and partially cured liquid from the object. (F) Should be as non-toxic and non-irritating as possible.

The cured material must have the desired properties once it is in the solid state. These properties, like those of other plastic materials in general, are application-related. Color, texture, strength, electrical properties, flammability and flexibility are properties to consider. Additionally, the cost of materials is often also important.

The UV curable material used in the presently preferred embodiment of a practical stereolithography system (e.g., Figure 3) is Loctite Limited.
Potting Compound, a modified acrylate manufactured by
Compound) 363. A method for making this typical UV curable material is described in US Pat. No. 4,100,141.

That is, the UV curable materials described above can be cured by free radical copolymerization using a myriad of known initiators as free radicals. Such initiators include peroxides such as hydrogen peroxide; organic peroxides such as benzoyl methyl ketone peroxide; 2.
Azo compounds such as 2'-azobis(isobutyronitrile); hydroperoxides such as cumene hydroperoxide, t-butyl hydroperoxide, methyl ethyl ketone hydroperoxide; hydrates such as t-butyl perbenzoate, t-butyl peracetate peresters that decompose into peracid compounds; photosensitive compounds such as benzophenone and benzoyl ether; A spot 27 of UV light is generated that is strong enough to cure quickly enough to be practical. source 26
is configured such that it can be programmed to turn on and off and to move the focusing spot 27 across the surface 23 of the liquid 22. Thus, as the spot 27 moves, it hardens the liquid 22 into a solid and forms a pattern on a surface in much the same way that a chart recording or drafting device uses a pen to draw a pattern on a piece of paper. Draw a solid pattern.

The light source 26 of the stereolithography apparatus of the presently preferred embodiment uses a 350 watt short arc mercury lamp located within the housing, and the light output of the housing is coupled to a 1 mm diameter UV transparent optical fiber bundle (not shown in the figure). (not) focused at the edge. The end of the bundle near the mercury lamp was water cooled, and an electronically controlled shutter plate was provided between the lamp and the end of the bundle to turn the light through the bundle on and off.
The bundle was 1 m long and the light output was fed into a lens tube with a quartz lens to focus the UV to a spot. The light source 26 is capable of producing a spot slightly less than 1 mm in diameter and has a longwave UV intensity of about 1 watt/cm ² .

In the apparatus of FIG. 3, the surface 23 is maintained at a constant height and means are provided for replenishing this material after the object has been removed, so that the focal spot 27 remains sharply focused on a constant focal plane. , thus ensuring maximum resolution when forming thin layers along the working surface. At this point, work surface 2
3. Form a focal point to obtain a region of high strength and rapidly diverge to a lower strength to limit the depth of the curing process to obtain the thinnest cross-sectional laminate suitable for the object being formed. It is desirable that the This uses a lens with a short focal length and the source 2
6 as close to the work surface as possible to maximize divergence in the focal cone entering the fluid medium. As a result, the resolution is substantially higher.

A model H-P9872 digital plotter (not shown), manufactured by Heuret-Paccard, Inc., is used to power the light source 26. The lens tube is attached to the plotter's pen cartridge and the plotter is driven by computer 28 using conventional graphics commands. The shutter is controlled by a model H-P3497 data acquisition/control unit using computer commands.

Other physical forms of light source 26 or equivalents thereof may be used. Scanning can be performed using an optical scanner, thus eliminating the need for optical fiber bundles and digital plotters. Ultimately, UV lasers will be a better light source than short-arc lamps. The speed of the 3D printing process mainly depends on the intensity of the light source and
limited by the response of the UV curable liquid.

A lifting platform 29 is used to support and hold the object 30 being formed and to move it up and down. Typically, after one layer is formed, the object 30 is moved beyond the level of the next layer (overdip into the liquid medium) so that solids are left on the surface 23 where they have formed. Allow liquid 22 to flow into the temporary void and then return to the correct height for the next layer. As a result, the liquid 22 that has flowed into the cavity recedes like a receding tide, forming a layer of a predetermined thickness. This allows automatic lamination of extremely thin layers. The requirements for the platform 29 are that it be able to move as programmed with reasonable speed and accuracy, and that it be strong enough to withstand the weight of the object being formed. Furthermore, manual fine adjustment of the position of the lifting platform is helpful during the setup phase as well as when removing objects.

The lifting platform 29 in the embodiment of FIG. 3 is a platform attached to an analog plotter (not shown). The plotter is driven by an HP3497 data acquisition/control unit with an internal digital-to-analog converter under program control of computer 28.

The computer 28 of the three-dimensional modeling apparatus of this invention basically has two functions. First, it helps the operator design a three-dimensional object in such a way that it can be created. Second, convert this design into appropriate commands for stereolithography and send these commands so that the object is formed. In some applications, there is a design of the object, and the only action of the computer is to issue appropriate commands or commands.

In an ideal case, an operator would design an object and
You can see it in three dimensions on the CRT screen of the calculator 28. When the operator completes the design, he commands the computer 28 to create the object, and the computer issues appropriate commands for three-dimensional modeling.

In an example in which this invention is actually used, the computer 2
8 is an HP9816 and uses a basic operating system. A typical program is shown in the attached reference material. This system is programmed by the operator using the HP Graphics Language (command structure for the 3497A) and Basic Language commands.
The operator must also set the appropriate exposure time and speed for the UV cure time. In order to operate this device, we create an image of the object and write a program to drive the three-dimensional modeling device to create this object.

The drive for the platform 29 may be mechanical, pneumatic, hydraulic or electrical, and optical or electronic circuit feedback may be used to precisely control its position. The platform 29 is typically made of glass or aluminum, but any material to which a hardened plastic material will adhere is suitable.

In some cases, the calculator 28 may be unnecessary and a simpler dedicated programming device may be used, especially if only simple shapes are to be built. Alternatively, computer controller 28 may simply execute instructions generated by another, more complex computer. This is the case when some stereolithography devices are used to create an object and another device is used to initially design the object to be formed.

A constant level of liquid 22 at work surface 23 can be maintained using a computer-controlled pump (not shown). This necessity is due to the following reasons. That is, when the liquid is exposed to light, it contracts due to a change in its capacitance, and the liquid level changes. Further, when the lifting table 29 moves into the liquid, the volume of the liquid changes, and thereby the liquid level changes.
The thickness of the liquid layer is determined by the depth of the previous layer formed below the liquid level, so if the liquid level is not kept constant, the actual thickness of the layer formed will be This is because the thickness of the layer varies depending on the desired thickness of the layer, making it impossible to form a layer with an accurate thickness. driving a fluid pump or driving a liquid displacement device using any suitable liquid level sensing device and feedback circuit known in the art;
A solid rod (not shown) is driven that moves out of the fluid medium as the platform is moved deeper into the fluid medium, smoothing out the change in fluid volume and creating a constant surface on surface 23. Fluid level can be maintained. Alternatively, the light source 26 can be moved relative to the sensed liquid level 22 and automatically maintain sharp focus on the work surface 23. All of these alternatives can be easily accomplished with conventional software working in conjunction with computer controller 28.

After the three-dimensional object 30 is formed, the lifting platform 29
Raise the height and remove the object from the stand. Typically, this is followed by ultrasonically cleaning the object in a solvent, such as acetone, that does not dissolve the hardened solid medium, but dissolves the liquid state of the unhardened fluid medium. The object 30 is then placed under a strong ultraviolet light flood, typically a 200 watts per inch UV curing lamp;
Complete the curing process.

Furthermore, several containers 21 can be used when practicing the invention. Each container contains a different type of curable material and can be automatically selected by the stereolithography device. In this case, the various materials may be plastics of different colors or may have both insulating and conductive materials that can be used in the various layers of the electronic component.

Other embodiments of the invention will now be described with reference to the other drawings, where like reference numerals are used throughout the drawings to refer to parts similar to those described for the preferred embodiment of the invention shown in FIG. There is.

FIG. 4 shows another type of three-dimensional modeling apparatus. In this case, the UV curable liquid 22 etc. floats on top of the heavier UV transparent liquid 32. liquid 3
2 is immiscible with and does not wet the curable liquid 22. By way of example, ethylene, glycol or heavy water are suitable as the intermediate liquid layer 32. In the device of FIG. 4, the three-dimensional object 30 is lifted out of the liquid 22 instead of penetrating into the fluid medium as shown in the device of FIG.

A UV light source 26 in FIG. 4 focuses a spot 27 on the interface between liquid 22 and an immiscible intermediate liquid layer (mold release agent) 32. The UV radiation passes through a suitable UV-transparent window 33 made of quartz or the like supported in the bottom of the container 21. The curable liquid 22 is provided as a very thin layer on top of the immiscible layer 32, thus limiting the depth of curing since ideally a very thin laminate should be produced. There is the advantage of directly limiting the layer thickness instead of relying solely on adsorption etc. Therefore, the formation area is more sharply limited, and if the apparatus shown in FIG.
Certain surfaces are formed more smoothly than the device shown. Additionally, the UV curable liquid 22 requires less volume and is easier to replace one curable material with another.

The device in FIG. 5 is similar to the device in FIG. 3, but
There is no movable UV light source 26, and instead of a programmed source 26 and focusing spot 27, a collimated wide UV light source 35 and a suitable aperture mask 36 are used. The aperture mask 36 is placed as close as possible to the work surface 23 so that collimated light from the UV source 35 passes through the mask 36 to expose the work surface 23, thus similar to the embodiment of FIGS. , making successive adjacent laminates.
However, by using a fixed mask 36 that represents the cross-sectional shape of the object to be formed, a three-dimensional object with a constant cross-sectional shape can be obtained. When changing this cross-sectional shape, create a new mask 3 for that specific cross-sectional shape.
6 and have to match it correctly. Of course, by providing a web of the mask (not shown) which is successively moved into alignment with the surface 23, the mask can be changed automatically.

FIG. 6 also shows a three-dimensional modeling apparatus similar to that previously described with respect to FIG. However, the light source 26
and as a replacement for the focal spot 27, a cathode ray tube (CRT) 38, an optical fiber face plate 39;
and a water or other template layer 40. To this end, the image output from the computer 28 to the CRT 38 forms an image on the UV-emitting phosphor surface of the tube, where it passes through the optical fiber layer 39 and the template layer 40 and into the working surface 23 of the fluid medium 22. In all other respects,
The apparatus of FIG. 6 forms successive cross-sectional laminates that define the desired three-dimensional object to be formed, just as in the previously described embodiments.

7 and 8 show a three-dimensional modeling apparatus in which the lifting platform 29 has additional degrees of freedom, allowing different sides of the object 30 to be exposed for other construction methods. Similarly, this stereolithography method can be used as an "add-on" method, and the lift platform 29 can be used to pick up and position additional parts for supplementary stereolithography processing. In this respect, the apparatus shown in FIGS. 7 and 8 is the same as that shown in FIG. 3, except that in the apparatus of FIGS. Or, it differs in that it has a second degree of freedom of automatically controlled rotation. In this regard, FIG. 7 shows the adjustable lifting platform 29a in the normal position.
FIG. 8 shows the table 29a rotated by 90 degrees, so that an auxiliary structure 41 formed by three-dimensional modeling can be selectively added to one side of the three-dimensional object 30. can be formed into

Practical stereolithography devices have additional components and subsystems beyond those previously described for the devices shown schematically in FIGS. 3-8. For example, a practical device has a frame and housing and a control panel. Additionally, means may be provided to shield the operator from excess UV and visible light, and may also be provided to allow the operator to view the object 30 while it is being formed. Practical equipment includes safety measures to control ozone and harmful fumes, as well as high pressure safety protection and interlocking devices. Such practical devices also have means for effectively shielding sensitive electronic circuitry from noise sources.

As already explained, many other devices can be used to carry out the three-dimensional modeling method of the present invention. For example, instead of the UV light source 26,
A suitable fluid medium that hardens in response to a particular type of reactive energy, which can be an electron source, a visible light source, a laser light source, a shot arc light source, a high energy particle light source, an X-ray source or other radiation source;
For example, photopolymerizable materials can be used. For example, alpha octadecyl acrylic acid, which has been slightly prepolymerized using UV light, can be polymerized using an electron beam. Similarly, poly(2,3-
dichloro-1-propyl acrylate) can be polymerized using an X-ray beam.

〔Effect of the invention〕

The stereolithography method and apparatus of the present invention has many advantages over methods currently used for manufacturing plastic objects. The method of the present invention does not require the creation of design layouts and drawings, nor does it require the creation of processing drawings and tools. Designers can work directly with computers and stereolithography equipment, and when they are satisfied with the design displayed on the computer's output screen, they can directly review it.
Parts can be manufactured. When a design needs to be changed, it can be easily done through a computer, and then another part can be made to verify that the change was correct. If a design requires several parts with interacting design parameters, the design of all parts can be quickly changed and recreated. This allows the entire assemblage to be constructed and tested repeatedly, if necessary.
The method of this invention is further useful.

Once the design is complete, manufacturing of the parts can begin immediately, thus avoiding weeks or months between design and manufacturing. The final production rate and cost of parts should be similar to the cost of current injection molding for short run production, and labor costs can be even lower than with injection molding.
Injection molding is economical only when large numbers of identical parts are required. Stereolithography is useful for short-term production. This is because no tools are required and the production set-up time is very short. Similarly, design changes and custom parts are easily obtained using this method. Because it is easy to make parts,
Stereolithography allows plastic parts to be used in many places where parts of metal or other materials are currently used. Additionally, a plastic model of the object can be made quickly and economically before a decision is made to manufacture the more expensive metal or other material parts.

Although various three-dimensional modeling devices for carrying out this invention have been described above, it is clear that they all share the idea of drawing a nearly two-dimensional surface and pulling up a three-dimensional object from this surface. be.

The present invention addresses a long-standing need for a CAD and CAM system that can quickly, reliably, accurately and economically design and manufacture three-dimensional plastic parts and the like.

While the invention has been illustrated and described in a particular form, it will be obvious that various modifications may be made within the scope of the invention. Therefore, this invention is not limited only to the scope of the claims of the present application.

[Brief explanation of drawings]

1 and 2 are flowcharts showing the basic idea used to implement the three-dimensional modeling method of this invention, and FIG. 3 is a cross section of a currently preferred embodiment of an apparatus for implementing this invention. 4 is a sectional view of a second embodiment of the invention, FIG. 5 is a sectional view of a third embodiment of the invention, and FIG. 6 is a sectional view of a third embodiment of the invention. FIGS. 7 and 8, which are cross-sectional views of still another embodiment, are partial cross-sectional views of the three-dimensional modeling apparatus of FIG. 3 modified to incorporate a lifting platform with multiple degrees of freedom. 21... Container, 22... UV curable liquid, 23... Work surface, 26... Light source, 28... Calculator, 29... Lifting platform, 30... Object.

Claims (1)

[Scope of Claims] 1. A device for automatically creating a three-dimensional object from a hardenable fluid medium, comprising: an arithmetic device that generates data representing a cross section of the three-dimensional object to be created; a container containing the fluid medium; a non-reactive mold release fluid retaining a quantity of said fluid medium on a work surface; and exposing said fluid medium to curing radiation generated in response to said data to form a first cross-sectional layer on said work surface. and an apparatus for laminating the first cross-sectional layer with a subsequent fluid layer to form a second cross-sectional layer adhered to the first cross-sectional layer; A device that forms three-dimensional objects from cross-sectional layers. 2. The apparatus for forming a three-dimensional object according to claim 1, wherein the mold release liquid contains heavy water. 3. The apparatus for forming a three-dimensional object according to claim 1, wherein the mold release liquid contains ethylene glycol.