THREE-DIMENSIONAL PRINTER APPARATUS WITH PASSIVE LUBRICANT REPLENISHMENT

A three-dimensional printing system is provided that includes a tank, a textured substrate connected to the tank, and an auxiliary reservoir. The tank contains a liquid photopolymer resin. The textured substrate is configured to allow light to pass through into the liquid photopolymer resin. The auxiliary reservoir contains lubricant, and the textured substrate includes a plurality of internal channels connected to the auxiliary reservoir.

BACKGROUND

Field of the Invention

The present invention generally relates to a three-dimensional printing system with passive lubricant replenishment, and a textured window for such a three-dimensional printing system. The three-dimensional printing system includes a tank, a textured substrate connected to the tank, and an auxiliary reservoir. The tank contains a liquid photopolymer resin. The textured substrate is configured to allow light to pass through into the liquid photopolymer resin. The auxiliary reservoir contains lubricant, and the textured substrate includes a plurality of internal channels connected to the auxiliary reservoir. The textured window includes a first substrate that is optically transparent, and a second substrate formed on a surface of the first substrate. The second substrate has a textured surface and a plurality of internal channels formed in the second substrate.

Background Information

Three-dimensional (“3D”) printers have been used to print a wide variety of three-dimensional products. Objects are printed layer by layer by the 3D printer by curing portions of a light curable photopolymer resin layer by layer, one layer at a time, within a printing area of a tank filled with the photopolymer resin. A curing device, such as an ultraviolet light source, is projected through a transparent substrate or bottom wall of the tank curing each layer of the object on a carrier surface that is at least partially submerged within the photopolymer. The carrier surface is incrementally raised upward as each layer is cured thereon. One problem with such conventional arrangement is that portions of the photopolymer resin can adhere to the transparent substrate (bottom wall of the tank). This adhesion slows and/or delays the printing process, thereby decreasing productivity. It is therefore advantageous to prevent adhesion of the photopolymer to the transparent substrate.

In order to address this problem of adhesion, textured windows have been developed that include a textured surface in contact with the photopolymer resin. The textured surface includes grooves that are configured to hold lubricant. The textured windows are substantially transparent and can be used as the transparent substrate. By providing a layer of the lubricant between the photopolymer resin and the transparent substrate, adhesion between the photopolymer and transparent substrate can be reduced.

Although these lubricant-infused textured windows can improve the printing speed by increasing the slip length along the textured window in the print area, the amount of lubricant along the surface of the textured window is depleted over time. Therefore, adhesion between the photopolymer and the transparent substrate can still become a problem when the amount of lubricant lost reaches a certain level. For example, a 20% loss in lubricant can render the textured window useless for printing due to adhesion problems. In addition, adhesion of the photopolymer to the transparent substrate can damage the textured window.

Therefore, further improvement is needed to reduce the adhesion of the photopolymer to the transparent substrate. In particular, it is desirable to compensate for the loss of lubricant on the surface of the textured window over time and to thereby extend the time which the 3D printer can continuously print.

SUMMARY

It has been discovered that the lubricant lost over time can be compensated for by providing a stacked replenishment system in which lubricant is passively replenished through layers in the textured window. The system includes a textured window having internal channels and an auxiliary reservoir that contains lubricant and is connected to the internal channels. By providing the auxiliary reservoir of lubricant and the internal channels in the textured window, lubricant lost over time can be replenished through the internal channels of the textured window to the surface facing the photopolymer resin while maintaining a simple system design. In particular, by replenishing the lubricant through the internal channels in the textured window, an even replenishment across the printing area can be ensured while maintaining the mechanical stability necessary for a flat printing surface. Lubricant can also be replenished through the textured window by providing at least one porous layer in the textured window between the printing surface and the internal channels.

Therefore, it is desirable to provide a three-dimensional printing system that includes such a stacked replenishment system with an auxiliary reservoir and internal channels in the textured window. It is also desirable to provide a textured window that includes a textured surface configured to hold lubricant and internal channels for allowing the lubricant to flow through the textured window to the textured surface.

In view of the state of the known technology, one aspect of the present disclosure is to provide a three-dimensional printing system. The three-dimensional printing system includes a tank containing a liquid photopolymer resin, a textured substrate connected to the tank, and an auxiliary reservoir containing lubricant. The textured substrate is configured to allow light to pass through into the liquid photopolymer resin. The textured substrate also includes a plurality of internal channels connected to the auxiliary reservoir. By providing the auxiliary reservoir and the plurality of channels in the textured substrate, lubricant lost during operation of the three-dimensional printing system can be passively replenished while maintaining a simple system design, thereby preventing adhesion of the liquid photopolymer resin to the textured substrate and allowing for longer and higher-speed continuous printing as compared with conventional three-dimensional printers.

Another aspect of the present disclosure is to provide a textured window for a three-dimensional printing system. The textured window includes a first substrate that is optically transparent and a second substrate formed on a surface of the first substrate. The second substrate has a textured surface and a plurality of internal channels formed in the second substrate.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring initially toFIG.1, a three-dimensional printer apparatus1(hereinafter the 3D printer apparatus1) is illustrated in accordance with a first embodiment. The 3D printer apparatus1includes a printer assembly2having a tank4. The printer apparatus1also includes a reservoir6, a pipe8, a rinse station10, a final curing station12, a robotic arm14and an object carrier16connected to the robotic arm14.

As shown inFIG.1, the printer assembly2, the reservoir6, the pipe8, the rinse station10, the final curing station12, the robotic arm14and the object carrier16are shown as an assembled group of devices. Alternatively, the 3D printer apparatus1can be separate stations that are individual units where the robotic arm14, or a series of robotic arms are operated together in order to access and utilize the features of each of separated versions of the printer assembly2, the rinse station10and the final curing station12. It should be understood that the 3D printer apparatus1can include any suitable devices in addition to the printer assembly1. For example, the 3D printer apparatus1can include only the printer assembly2and the robotic arm14.

The printer assembly2, the reservoir6, the pipe8, the rinse station10, the final curing station12, the robotic arm14and the object carrier16can each be formed of any suitable material, such as a plastic material, a polymer materials and/or a metallic material.

As shown schematically inFIG.2, the printer assembly2includes a tank4that has a textured window26and the object carrier16connected to the robotic arm18. The object carrier16is configured to carry an object20that is printed by the printer assembly2. The printer assembly2also includes a resin curing device28that emits ultraviolet light30. A more detailed description of each of these portions of the printer assembly2is provided after a brief overview of the basic functions of these features.

As is also shown inFIG.2, during operation of the printer assembly2, the tank4is at least partially filled with two differing liquid layers—top liquid layer22and bottom liquid layer24. The top liquid layer22is a polymerizable resin that covers the bottom liquid layer24. The top liquid layer22can be any suitable polymerizable resin, for example a photopolymer resin that is polymerized by the ultraviolet light30. The top liquid layer22is preferably a photopolymer resin. In particular, the top liquid layer22can be formed of: a nylon having a photoinitiator wavelength of 290-315 nm, an acrylic having a photoinitiator wavelength of 290-315 nm, a styrene acrylonitrile having a photoinitiator wavelength of 290-330 nm, a polycarbonate having a photoinitiator wavelength of 280-310 nm, a polystyrene having a photoinitiator wavelength of 310-325 nm, a polyethylene having a photoinitiator wavelength of 300-340 nm, a polypropylene having a photoinitiator wavelength of 290-370 nm, an acrylonitrile butadiene styrene (“ABS”) photopolymer having a photoinitiator wavelength of 300-385 nm, a polyvinyl chloride (“PVC”) homopolymer having a photoinitiator wavelength of approximately 320 nm, a PVC copolymer having a photoinitiator wavelength of 330-370 nm, a polyurethane (aromatic) having a photoinitiator wavelength of 350-415 nm, or a mixture thereof.

The top layer22flows freely into the printing area P during the operation of the printing assembly2, as is described in greater detail below. The polymerizable resin that forms the top layer22can be supplied to the tank4such that the polymerizable resin fills most or all of the interior volume of the tank4, depending upon the object20being printed and the anticipated volume of use of polymerizable resin needed to print the object20being printed by the printer assembly2.

The bottom liquid layer24is a lubricant that covers the textured window26and forms a liquid layer between the textured window26and the top liquid layer22. One of the purposes of the bottom liquid layer24is to separate and space apart the polymerizable resin in the top liquid layer22from the textured window26of the tank4. The bottom liquid layer24can be formed of any suitable lubricant, such as an oil having a low viscosity and low adhesion. For example, the bottom liquid layer24can be formed of a fluorinated oil. The fluorinated oil is preferably a perfluoropolyether (“PFPE”) copolymer, a fluorosilicone polymer, a perfluorocarbon liquid, allicin oil, garlic oil, a synthetic PFPE-based oil that contains polytetrafluoroethylene (“PTFE”) powder such as Krytox® GPL oil, Fomblin® Y PFPE oil, or a mixture thereof. The bottom layer24has a thickness of approximately 3 nm to 5 mm from the uppermost top surface of the textured window26facing the top liquid layer22to the bottom surface of the top liquid layer22facing the textured window26.

The textured window26is a structure formed at the bottom of the tank4as shown inFIG.2(a). The textured window26can be connected to the bottom of the tank4in any suitable manner or can be formed integrally with the bottom of the tank4. For example, the textured window26can be attached to bottom ends or bottom edges of each side wall of the tank4to form a liquid tight space within the tank4. The tank4can be manufactured of any suitable material, such as a plastic, a polymer, a metallic material, or mixtures thereof. The textured window26is also connected to the pipe8such that the liquid from reservoir6can be supplied to the textured window26. The textured window26has a total thickness of approximately 10 μm to 5 cm. The textured window26is optically transparent and has an ultraviolet light transmittance of at least 60%, preferably at least 90%, such that focused beams of light from the resin curing device28pass therethrough and at predetermined areas or portions of the polymerizable resin located within the printing area P.

The resin curing device28is installed or located below the tank4and is positioned to selectively project light upward through transparent textured window26of the tank4. An electronic controller (not shown) controls operation of the resin curing device28to cure and harden the polymerizable resin in the top liquid layer22located within the printing area P in order to form the object20. The resin curing device28can be any of a variety of resin curing light sources such as an ultra-violet projector, laser (stereolithography) digital light projector, liquid crystal display, projector or other light emitting device capable of electronic focusing and imaging focused light in order to selectively cure polymerizable resin to form the object20.

The printing area P is defined as being the space below the object carrier16(at and/or below a lower surface of the object20being printed) and the upper surface of the bottom liquid layer24. Further, the printing area P is preferably located above and spaced apart from the textured window26of the tank4but can be in contact with the textured window26if the bottom liquid layer24is depleted during operation.

As shown inFIG.2(b), the textured window26includes a first substrate32and a second substrate34provided on the top surface of the first substrate32. The first substrate32is formed of any suitable optically transparent material. For example, the first substrate32can be made of any suitable transparent material, such as plexiglass, traditional glass, any suitable transparent plastic or polymer material, or a mixture thereof. Preferably, the first substrate32is made of a glass material. The first substrate32has a thickness of approximately 9 μm to 3 cm.

The second substrate34can be formed on the top surface of the first substrate32in any suitable manner. For example, the second substrate34can be adhered to the first substrate32by an adhesive material. Alternatively, the second substrate34can be deposited on the first substrate32by any suitable deposition method, such as chemical vapor deposition (“CVD”), etching or additive and subtractive methods. The second substrate34is formed of any suitable optically transparent and soft polymer material. For example, the second substrate34can be made of an optically transparent silicone polymer such as polydimethylsiloxane (“PDMS”), an optically transparent fluorinated polymer, or a mixture thereof. Preferably, the second substrate34is made of PDMS. The second substrate34can also be porous. The second substrate34preferably has a porosity of approximately 30% to 70%. The second substrate34has a thickness of approximately 5 nm to 200 μm.

As shown inFIG.2(b), the second substrate34includes a plurality of grooves35on the top surface of the second substrate34facing the bottom liquid layer24. The grooves35form a textured surface on the top of the second substrate34facing the bottom liquid layer24. The grooves35are configured to hold liquid from the bottom liquid layer24and can have any suitable shape. For example, the grooves35have a pillar-like shape and are formed along the top surface of the second substrate34. Preferably, the grooves35have a cubic shape as illustrated inFIG.3with a same length, width and depth from the top surface of the second substrate34. The grooves35have a depth, length and width each ranging from approximately 0.1 μm to 100 μm.

The grooves35inFIG.3are shown from the bottom surface of the second substrate34. As shown inFIG.3, the grooves35are formed in a pattern along the top surface of the second substrate34. For example, as shown inFIG.3, the grooves35in the top surface of the second substrate34can be formed as a pattern of cubic pillars projecting toward the bottom surface of the second substrate. However, it should be understood that the grooves35can have any suitable shape for holding the lubricant in the bottom liquid layer24.

FIG.4shows an enlarged view of the textured window26, the reservoir6and the pipe8ofFIG.2(a). As shown inFIG.4, the second substrate34includes the plurality of grooves35on the top surface of the second substrate34facing the object20. As the resin in the top liquid layer22is cured, it forms a cured layer36between the object20being printed and the bottom liquid layer24.

The second substrate34also includes an internal channel38formed between two layers34of the second substrate34. The internal channel38is connected to the pipe8such that lubricant from the reservoir6can flow into the internal channel38of the second substrate34. The internal channel38has a height of approximately 0.01 μm to 50 μm in the z direction and a width of approximately 0.01 μm to 50 μm in the y direction. The internal channel38can extend any suitable length in the x direction along an internal surface of the second substrate34. The internal channel38preferably extends along an entire length of the second substrate34.

As discussed previously, the second substrate34is formed of any suitable optically transparent and soft polymer material. For example, the second substrate34can be made of an optically transparent silicone polymer such as PDMS, an optically transparent fluorinated polymer, or a mixture thereof. The second substrate34is preferably made of PDMS. The second substrate34is also porous and has a porosity of approximately 30% to 70% and a pore size of approximately 100 μm or less. The second substrate34has a thickness of approximately 5 nm to 200 μm.

As shown by the arrows inFIG.4, during operation of the printer assembly2, the lubricant from the reservoir6flows into the internal channel38of the second substrate34via the pipe8. The lubricant then flows from the internal channel38through the top layer of the porous second substrate34to the bottom liquid layer24. By supplying the lubricant from the reservoir6to the internal channel38of the second substrate34, lubricant lost during operation of the printer assembly2can be replenished without interrupting the operation of the printer assembly2, thereby allowing a longer continuous printing time.

Although not shown, it should be understood by those skilled in the art that the operation of the reservoir6can be controlled in any suitable manner. For example, the reservoir6can be controlled by an electronic controller such that when a sensor detects that the liquid level of the bottom liquid layer24or the liquid level of the reservoir6has fallen below a certain level, additional lubricant is supplied to the internal channel38from the reservoir6through the pipe8. Alternatively, the reservoir6can be controlled by an electronic or manual controller to supply lubricant to the internal channel38at predetermined times or time intervals.

FIGS.5(a) and5(b)show a textured window40for a 3D printer assembly in accordance with a second embodiment. The textured window40includes a first substrate44having a plurality of internal channels42formed therein. The first substrate44is a first layer of the textured window40. As shown inFIG.5(a), the internal channels42are formed in a leaf-like pattern on the surface of the first substrate44. The internal channels42each have a width of approximately 0.01 μm to 50 μm and extend along an entire length and width of the first substrate44. As shown inFIG.5(b), the internal channels42are grooves formed in the first substrate44. The internal channels42have a depth of approximately 0.01 μm to 50 μm from the top surface of the first substrate44.

The first substrate44is formed of any suitable optically transparent and soft polymer material. For example, the first substrate44can be made of an optically transparent silicone polymer such as PDMS, an optically transparent fluorinated polymer, or a mixture thereof. The first substrate44is preferably made of PDMS. The first substrate44is also porous and has a porosity of approximately 30% to 70% and a pore size of approximately 100 μm or less. The first substrate44has a thickness of approximately 5 nm to 200 μm.

As shown inFIGS.5(c) and5(d), the textured window40also includes a second substrate46. The second substrate46is a second layer of the textured window40. The second substrate46is formed of any suitable optically transparent and soft polymer material. For example, the second substrate46can be made of an optically transparent silicone polymer such as PDMS, an optically transparent fluorinated polymer, or a mixture thereof. The second substrate46is preferably made of PDMS. The second substrate46is also porous and has a porosity of approximately 30% to 70% and a pore size of approximately 100 μm or less. The second substrate46has a thickness of approximately 5 nm to 200 μm. The second substrate46is preferably made of the same material as the first substrate44.

The textured window40may also optionally include a third substrate (not shown) formed of an optically transparent material and disposed on the opposite side of the first substrate42from the second substrate46such that the first substrate42is provided between the second substrate46and the third substrate. The third substrate can be formed of any suitable optically transparent material, such as plexiglass, traditional glass, any suitable transparent plastic or polymer material, or a mixture thereof.

FIGS.6(a) and6(b)show a textured window50for a 3D printer assembly in accordance with a third embodiment. Like the textured window40of the second embodiment, the textured window50includes a plurality of internal channels52formed in a first substrate54. The first substrate54is a first layer of the textured window50.

However, as shown inFIGS.6(a) and6(b), the internal channels52are formed in a grid-like pattern on the surface of the first substrate54, rather than a leaf-like pattern as in the third embodiment. However it should be understood that the internal channels52may be formed in any suitable pattern on the surface of the first substrate54. The internal channels52each have a width of approximately 0.01 μm to 50 μm and extend along an entire length and width of the first substrate54. The internal channels52are grooves formed in the first substrate54. The internal channels52have a depth of approximately 0.01 μm to 50 μm from the top surface of the first substrate54.

The first substrate54is formed of any suitable optically transparent and soft polymer material. For example, the first substrate54can be made of an optically transparent silicone polymer such as PDMS, an optically transparent fluorinated polymer, or a mixture thereof. The first substrate54is preferably made of PDMS. The first substrate54is also porous and has a porosity of approximately 30% to 70% and a pore size of approximately 100 μm or less. The first substrate54has a thickness of approximately 5 nm to 200 μm.

As shown inFIG.6(b), the textured window50also includes a second substrate56as a second layer of the textured window50. The second substrate56is formed of any suitable optically transparent and soft polymer material, such as an optically transparent silicone polymer, an optically transparent fluorinated polymer, or a mixture thereof. The second substrate56is preferably made of PDMS. The second substrate56is also porous and has a porosity of approximately 30% to 70% and a pore size of approximately 100 μm or less. The second substrate56has a thickness of approximately 5 nm to 200 μm. The second substrate56is preferably made of the same material as the first substrate54.

The textured window50may also optionally include a third substrate (not shown) formed of an optically transparent material and disposed on the opposite side of the first substrate52from the second substrate56such that the first substrate52is provided between the second substrate56and the third substrate. The third substrate can be formed of any suitable optically transparent material, such as plexiglass, traditional glass, any suitable transparent plastic or polymer material, or a mixture thereof.

By providing the textured window having a plurality of internal channels and an auxiliary reservoir connected to the textured window, lubricant lost during operation of the printer assembly can be replenished, thereby ensuring an increased slip length on the textured surface of the textured window and a faster printing time by preventing adhesion of the cured material to the textured window. Furthermore, by providing the textured window with porous layers, lubricant can be passively supplied to the textured surface of the textured window from the internal channels through the porous layers of the textured window.

General Interpretation of Terms

The terms of degree, such as “approximately” or “substantially” as used herein, mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed.