Patent Application
20170291355
The present invention relates to a 3D printer. More particularly, the 3D printer is based on Digital Light Processing, and the photopolymer resin is cured at the top surface which is regulated by a plane film.
Three dimensional (3D) printing is a process to form a three-dimension object. Different from traditional processes such as casting and cutting, 3D printing utilizes adding instead of removing materials to form the solid object which could have complex shape or geometry. This process is also known as additive manufacturing (AM), rapid prototyping or solid freeform fabrication. The machine to perform the process is called 3D printer.
Basically, 3D printing is achieved by building an object layer by layer from a particular material such as powered metal, droplets of plastic or any other appropriate material. Each of these layers is a thin slice cross-section of the eventual object which is generated by process similar to regular 2D printing in x and y dimensions. All layers are laid over successively in z dimension. With the thickness of these layers accumulated, a 3D object is formed.
There are number of different technologies developed based on different materials and the ways to form the layers, for example, Fused Deposition Modeling (FDM), Stereolithography (SLA), 3D Inkjet Powder (3DP), Selective Laser Sintering (SLS).
Digital Light Processing (DLP) is one of the well developed technologies recognized by its relatively high resolution and high speed. In this process, liquid solidifiable material (e.g., photopolymer resin) contained in a vat is exposed to visible light or UV light generated by DLP projector. The DLP projector displays the image of the 3D model onto the surface of the liquid solidifiable material. The exposed solidifiable material is solidified (or cured) to form a solid layer with desired pattern according to the image. Then the object is drawn away from the surface to let the liquid solidifiable material to fill in for next layer. By repeating the process a new layer is formed over previous layer until the 3D object is complete. Compare with SLA which uses a UV laser beam to cure the photopolymer resin spot by spot, DLP generates irradiation over its display area simultaneously to tremendously increase the curing speed. At the same time, benefiting from the projector technology, high resolution is available.
There are two ways to cure solidifiable material in DLP. One is called “top-down” in which new layers are formed at the top surface of the growing object. In this method, after each irradiation step the object under construction is submerged into the liquid solidifiable material, a new layer of solidifiable material is coated on top, and a new irradiation step takes place. During this process, it is necessary to reconstitute a layer of solidifiable material accurately because the thickness of the layer defined the resolution in z dimension. Obviously, this increases the processing time and complexity of the system. At the same time, the surface of each solidified layer must be smooth and planar in order to apply new irradiation step. Some techniques utilize of a paddle or a blade to sweep across the surface of the solidified layer to remove irregularities in the surface profile thereof. One of the reasons of the irregularities is surface tension because the top surface of the material is exposed to air. Again, this technique introduces additional processing time and mechanical complexity.
The other technique is called “bottom-up” in which new layers are formed at the bottom surface of the growing object. After each irradiation step the object under construction must be separated from the bottom plate of the vat. One big issue with such “bottom-up” techniques is that an accurately controlled force must be applied when separating the solidified layer from the bottom plate caused physical and chemical adhesive effect. Sometimes the required separation force is so great that it can deform or break the object.
Although DLP is already widely used and is available for desk-top printing, the application in commercial level is still limited. There are two disadvantages preventing DLP from involving in more area. First, the size of the object is limited; second, the process is still not fast enough.
Since the light source is DLP projector, the size of the object in x and y dimension is limited by the display area of the projector. But based on current projector performance, the display area can't be enlarged without sacrificing the resolution.
In bottom-up technique, larger size in x and y dimension means larger contact area between solidified material and the bottom of the vat, this will request larger separation force. However solidified material can only afford limited separation force to avoid deformation and which also restricts the size of the object.
Regarding processing speed, the operations of the surface of the object, such as sweeping the surface with a paddle, or separating the object form the bottom of the vat, consume a large amount of time.
Considering all these disadvantages mentioned above, it would be desirable to provide an apparatus and method in 3D printing to enlarge the object dimension, reduce the processing time, and simplify the mechanism.
The primary objective of the present invention is to develop a 3D printing apparatus and method applicable in commercial applications.
Another objective of the present invention is to develop a 3D printing apparatus and method to fabricate objects with large dimensions.
Another objective of the present invention is to develop a 3D printing apparatus and method to fabricate objects with high speed.
Another objective of the present invention is to develop a 3D printing apparatus with simplified mechanism.
The invention comprises the following, in whole or part:
An irradiation component, a solidifiable material container, a supporting component, a surface regulation component, and a control system.
The irradiation component comprises a projector to generate irritation over designated area on the top surface of the solidifiable material.
The solidifiable material container contains the liquid solidifiable material.
The supporting component provides a substrate for the solidifiable material to be solidified over it to form the object, and levels the solidified lay of the object at a desired position.
The surface regulation component comprises a regulation plane which provides a flat and smooth surface. This regulation plane is placed over the liquid solidifiable material therefore the top surface of the liquid solidifiable material is covered by the surface of the regulation plane. In this way a portion of the surface of the liquid solidifiable material is regulated in flat, the surface tension effect is eliminated. The surface regulation component also comprises a mechanism to peel the regulation plane from the solidified layer of the under building object.
The control system provides data to the projector for generating desired patterns, and controls the irradiation component, the supporting component, and the surface regulation plane to cooperate together.
For a more complete understanding of the present invention with its objectives and distinctive features and advantages, reference is now made to the following specification and to the accompanying drawings.
In accordance with a preferred embodiment,
The irradiation component 10 comprises an irradiation source 11 which generates desired irradiation. In a preferred embodiment, the irradiation source 11 is a DLP projector 11 which generates visible light, UV light, or other forms of light. The irradiation component 10 also comprises a positioning mechanism 12. The positioning mechanism 12 is controlled by the control system 50 to move the projector 11 vertically (in z direction), and position the projector 11 with a predetermined height over the surface of the liquid solidifiable material 21. By adjusting the height, the resolution and display area of the projector 11 can be accurately controlled if the projector 11 is focused.
In a preferred embodiment of the present invention, the positioning mechanism 12 also moves the projector 11 horizontally (in x and y directions). In this manner, the irradiation area of a single projector can be extended, which means the size of the cross section of the object 60 will not be limited by the display area of the projector 11.
The solidifiable material container 20 is a vat with an opening at the top. The vat 20 contains solidifiable material 21 which can be solidified by the irradiation generated by the projector 11. In a preferred embodiment, the solidifiable material 21 is a liquid photopolymer resin. The solidifiable material container 20 has a predetermined size in x, y and z dimensions which is enough to merge the whole 3D object 60 within.
The supporting component 30 comprises an object platform 31 providing a substrate for the object 60 to be laid upon and supporting the under building object 60. The object platform 30 also comprises a supporting mechanism 32 which is mechanically coupled with the object platform 31. The supporting mechanism 32 moves the object platform 31 in z direction and can submerge the object 60 in the resin 21 and let a layer of liquid resin 21 with predetermined thickness fill over the top surface of the under building object 60.
The surface regulation component 40 comprises a regulation plane 41 which is transparent to the irradiation, and a supporting frame 42 which retains the regulation plane 41. The regulation plane 41 has a smooth and planar surface facing the resin 21 and is leveled in parallel with the surface of the resin 21. The supporting frame 42 places the regulation plane 41 on the surface of the resin 21 with no gap in between, therefore the regulation plane 41 is fully contacted with the surface of the resin 21. In this manner, the contact area of the resin 21 under the regulation plane 41 is regulated into a smooth plane. This eliminates the irregularities caused by surface tension effect, etc.
The object platform 31 of the supporting component 30 is under the regulation plane 41. Through the operation of the supporting mechanism 32, the top surface of the under building object 60 is placed beneath the regulation plane 41 with a predetermined distance so a thin layer of liquid resin is filled in between. The projector 11 of the irradiation component 10 is positioned above the regulation plane 41 by the positioning mechanism 12 and projects irradiation over the thin layer of the resin 21 through the regulation plane 41. This thin layer of liquid resin 21 will be cured by the irradiation on the top surface of the under building object 60 to form a new solidified layer.
Referring to
Referring to
In a preferred embodiment of the present invention, the regulation plane 41 is formed by a transparent flexible film 43 which is shaped by the supporting frame 42. Preferably, the film 43 is an elongated band with the two ends rolled. Referring to
Once the liquid resin 21 is cured under the regulation plane 41, the new solidified layer may be adhered to the regulation plane 41 due to physical and chemical interaction. Therefore the regulation plane 41 needs to be lifted away from the solidified layer.
Referring to
Once the first and second shaft 423, 424 are closed together, the film 43 is totally separated from the solidified layer of the object 60. Then the object 60 will be lowered by the supporting component 30 to fill a new layer of resin 21. To regulate the new layer of resin 21, the first holder 421 and the first shaft 423 are moved away from the second holder 422 and second shaft 424. If the first holder 421 releases the rolled film 43, the old area of the film 43 will be reused as the regulation plane 41. If the second holder 422 releases the rolled film 43, new area of the film 43 will be used as the regulation plane 41.
In prior art of bottom-up technique, the object needs to be pulled from the bottom of the vat which is a rigid surface. Therefore the tensile force applied should overcome the adhesive force from the whole area of the solidified layer. But in the present invention, the flexible film 43 is peeled from the solidified layer. Therefore, only adhesive force from the edge of the film 43 under the shaft needs to be overcome. Compare with the whole area of the solidified layer, the area of the edge under the shaft is much less. Consequently, the required peeling force is much less.
In an alternative embodiment of the present invention, the supporting frame 42 moves the two holders 421, 422 and the two shafts 423, 424 together in x direction. During the movement, the two holders 421, 422 roll and unroll the film 43 respectively to maintain the tension, and remain the regulation plane 41 relatively still with the resin 21. For example, referring to
It is worth mentioning, once the film 43 is peeled, the same area of the film 43 can be reused. Or alternatively, used area will be rolled in by the first holder 421, and new area will be rolled out by the second holder 422, new area of the film 43 can be applied to form the regulation plan 41 for next layer of solidification.
The control system 50 is electrically connected with the irradiation component 10, the supporting component 30, and the surface regulation component 40. The control system 50 provides data to the irradiation component 10 for generating required display, at the same time controls the movement of the other components to perform 3D printing.
In one embodiment of the present invention, the dimension of the cross section of the object 60 is larger than the display area of the projector 11. In order to irradiate the entire area of the cross section of the object 60, the projector 11 is moved by the positioning mechanism 12 horizontally to irradiate different area. Referring to
Referring to
While the embodiments and alternatives of the invention have been shown and described, it will be apparent to one skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention.
