Patent Application
20180257302
The present invention generally relates to a multi-modal printing system and method of operating the same.
Stereolithography is an early method of three-dimensional printing by adding one layer of material on top of another. The first additive manufacturing process involves focusing and moving an ultraviolet (UV) laser, controlled by a computer aided design software (CAD), on the surface of a vat of photopolymer resin. As photopolymers are photosensitive to UV light, undergoing a polymerization reaction and solidifying to form a single microns-thick layer of the desired three-dimensional object. The curing process is repeated, alternating with a recoating process to reposition and coat the prior cured parts in uncured resin, for each layer until the entire object is completed. Today, most modern vat-type stereolithography apparatus typically have a recoater which holds resin inside the recoater above the liquid surface, and sucked from the vat by negative pressure. This reservoir of negative pressure resin coats the dry parts of the exposed object. Traditional stereolithography apparatus without recoaters dip the part further into the liquid than the layer thickness to suck additional resin above the part, the part is then raised to the appropriate depth to set the layer thickness. A pause is now necessary for the resin to level or a levelling device is activated. All stereolithography printers require certain manual intervention to reset the print surface and start the next print job.
There are speed limitations when using a negative pressure recoater because there is an additional step required in the process to fill the recoater with photoresin from the vat. Traditional stereolithography machines employing a static vat and a leveller require the z-stage to move much further than the layer thickness to overcome surface tension to pull resin on top of the cured part. These inefficiencies in the layer resetting mechanisms add unproductive time (time not spent curing) to the operation of stereolithography machines. In addition, as convenience has not been a priority of the 3D printing industry or manufacturers, human intervention is required to remove printed parts, clean the print surface and start any subsequent print jobs. Efficient and continuous operation of the printer cannot be achieved if the steps of, removing the printed part, cleaning the print surface and restarting the printer, was forgotten or delayed by its human operator. This loss of machine time is evident if a stereolithography machine is not operated in a shift environment and is inefficient to any company operating such a machine. The technologies described in embodiments of the present invention seek to improve the general speed and convenience of operation of 3D Printers.
Accordingly, a need exists to provide a stereolithography machine that seeks to address some of the above problems. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.
According to a first aspect of the present invention, there is provided a multi-modal printing system for printing a 3-dimensional object, comprising multiple layers of photoresin, in a stereolithography apparatus comprising a high speed resin applicator for applying the layers of photoresin, wherein the multi-modal printing system comprises a control mechanism configured to selectively control the high speed resin applicator to perform a discreet operation, a continuous operation, and a self-reset operation.
In an embodiment, the high speed resin applicator simultaneously sets and levels a layer of photoresin during a layer reset operation.
In an embodiment, the stereolithography apparatus may further comprise an expandable vat having a volume defined by vat sidewalls and a base, and the control mechanism is configured to expand a volume of the vat.
In an embodiment, the control mechanism may be configured to control the high speed resin applicator to travel at a fixed height relative to the top of the side walls of the vat, and to apply one of the multiple layers of photoresin while simultaneously levelling the layer of photoresin, the layer of photoresin being applied on a curing plane defined within the vat sidewalls.
In an embodiment, the expandable liquid vat may be liquid-tight and the control mechanism may be configured to displace the vat side walls upward relative to the base by a distance equal to a thickness of the layer of photoresin, thereby expanding the volume of the vat, after the layer of photoresin has been applied by the applicator.
In an embodiment, the expandable liquid vat may be liquid-tight and the control mechanism may be configured to displace the base of the vat downward relative to the vat sidewalls by a distance equal to a thickness of the layer of photoresin, thereby expanding the volume of the vat, after the layer of photoresin has been applied by the applicator.
In an embodiment, the expandable liquid vat may be liquid-tight and the control mechanism may be configured to displace the vat sidewalls and base relative to each other, by upward movement of the vat sidewalls relative to the base and downward movement of the base of the vat relative to the vat sidewalls, by a distance equal to a thickness of the layer of photoresin, thereby expanding the volume of the vat, after the layer of photoresin has been applied by the applicator.
In an embodiment, the side walls of the vat may be raised, by said distance, when the high speed resin applicator reaches an end of the vat in a two-way operation and the high speed resin applicator applies resin while travelling in both directions.
In an embodiment, the side walls of the vat may be raised, by said distance, when the high speed resin applicator reaches a specific end of the vat in one direction of a one-way operation and the applicator applies resin while travelling in the one direction.
In an embodiment, the stereolithography apparatus may further comprise a tracking device controlled by the control mechanism to track movement of the high speed resin applicator during the continuous operation.
In an embodiment, the tracking device may be configured to continuously measure the high speed resin applicator position.
In an embodiment, the stereolithography apparatus may further comprise a curing device that is above the vat.
In an embodiment, the stereolithography apparatus may further comprise a curing device that is above the vat and the curing device is configured to move upwards with respect to the base of the vat during every layer reset to maintain the curing device at a fixed height relative to the curing plane.
In an embodiment, the stereolithography apparatus may further comprise a special-shaped print tray for utilizing during the self-reset operation.
In an embodiment, the special-shaped print tray may comprise a recessed portion on the upper surface of the print tray to allow a photoresin to cure in a partially attached base layer; and a cutter, wherein the recessed portion is coupled to a hydraulic pump which is configured to pressurize the resin under the base layer to detach and bulge out the majority of the base layer in preparation for cutting and wherein the cutter detaches the outer edge of the finished product from the print tray and deposits the finished product in a collection bin.
In an embodiment, the special-shaped print tray may comprise a low stick material selected from the group of materials comprising acrylonitrile butadiene styrene (ABS), Teflon®, Teflon® derivatives, Polyethylene, Polystyrene, Polypropylene, Nylon, Polyamide, Polymethyl methacrylate (PMMA), Polyurethane, polyvinyl chloride (PVC), aluminum, aluminum alloys, magnesium, magnesium alloys, titanium, titanium alloys, steel, Inconel, cast iron, copper based alloys, bronze, brass, glass, quartz, alumina, and zirconia.
According to a second aspect of the present invention, there is provided a method for printing a 3-dimensional object in a stereolithography apparatus having a control mechanism and a high speed resin applicator for applying a layer of photoresin to a part being printed by the stereolithography apparatus, the control mechanism configured to selectively control operation of the apparatus, the method comprising controlling the high speed resin applicator, using the control mechanism, to perform a 3-dimensional printing operation comprising at least one of a discreet operation; a continuous operation and a self-reset operation.
In an embodiment, the stereolithography apparatus may comprise an expandable vat having vat sidewalls and a base, the vat containing liquid and the part being printed by the stereolithography apparatus, and wherein performing the discreet operation comprises the steps of moving the vat sidewalls upwards by a thickness of the layer of photoresin; applying a layer of photoresin, using a high speed resin applicator, on top of the liquid and part simultaneously while levelling the layer of photoresin; and pausing application of the layer of photoresin and, while addition of the layer of photoresin is paused, curing a single cross sectional layer of the part using a curing device maintained at a fixed height relative to the layer of photoresin.
In an embodiment, the stereolithography apparatus may comprise an expandable vat having vat sidewalls and a base, the vat containing liquid and the part being printed by the stereolithography apparatus, and wherein performing the continuous operation comprises the steps of moving the vat sidewalls upwards by a thickness of the layer of photoresin; applying a layer of photoresin, using a high speed resin applicator, on top of the liquid and part simultaneously while levelling the layer of photoresin; continuously applying resin and simultaneously curing the part using a curing device maintained at a fixed height relative to the cure plane; and measuring a position of the applicator continuously to allow projection of different layer images before and after application of the layer of photoresin, thus curing two different cross sectional layers simultaneously without having to pause the applicator during the curing process.
In an embodiment, the stereolithography apparatus may comprise a print tray within the vat and operating in the self-reset operation comprises the steps of upon application of a final layer of photoresin for completing 3-dimensional printing of the part, pressurizing the final layer of photoresin under a base layer to detach the majority of the base layer, wherein the base layer is a layer of photoresin applied first during 3-dimensional printing of the part; separating the part from the print tray by using a cutter to detach an outer edge of the part from the tray; and depositing the part into a collection bin.
Embodiments of the invention will be better understood and readily apparent to one of ordinary skill in the art from the following written description, by way of example only, and in conjunction with the drawings, in which:
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description. Herein, a multi-modal printing system and method of operating the same are presented in accordance with present embodiments having the advantages of faster print speeds, improved durability, enhanced efficiency and greater performance.
As shown in
In one embodiment in
In the discreet one-way operation as shown in
Thereafter, the curing device 114 above the vat 102 selectively cures the required areas of the applied layer of photoresin 106 after the layer reset operation whereby the high speed resin applicator 110 returns to its original starting position. The curing device 114 is further configured to move upwards 118 with respect to the base of the vat during every layer reset operation to maintain the curing device 114 at a fixed height relative to the curing plane. After curing of the layer of photoresin 106, the high speed resin applicator 110 applies the next layer of photoresin and the process is repeated until the desired three-dimensional object is printed.
By providing movable vat sidewalls 104a 104b which expands the volume of the vat 102 and adding a layer of photoresin 106 on the existing cured part and liquid resin while simultaneously levelling, it is possible to reduce the time spent on the layer resetting process over current stereolithography machines. The above described embodiment may also increase printing speeds of up to 300 millimetres per hour over current printers which currently have a maximum printing speed of 15 millimetres per hour.
Similar to
When the high speed resin applicator 210 reaches the opposite end of the vat, the sidewalls 204a 204b are raised a distance equal to a thickness of the layer of the photoresin 206. The high speed resin applicator 210 applies the next layer of photoresin in the opposite direction and the leveler 208a simultaneously levels the layer of photoresin after application. Thus, the high speed resin applicator 210 applies photoresin on the vat while travelling in both directions and the sidewalls 204a and 204b are similarly raised in this two-way operation. The apparatus 200 may also comprise a tracking device (not shown) controlled by the control mechanism to track movement of the high speed resin applicator 210 during the continuous operation. The tracking device is further configured to continuously measure the position of the high speed resin applicator 210. The position of the high speed resin applicator 210 is relayed to a computer or software and the curing device 214 continuously adjusts the image projected onto the cure surfaces. This allows different layers to be cured in front and behind the high speed resin applicator 210. For example, as shown in
The two way operation of the apparatus 200 in
The autonomous method for separating the printed object from the tray 302 as described above allows for continuous printing of multiple objects with no human intervention required. A print queue can be established and the apparatus 100200 can be used without the need for manual intervention to reset the print surface. Therefore, print time may be faster and greater efficiency may be achieved.
Thus it can be seen that the apparatus in accordance with the present embodiments have the advantages of improving the print speed for a three-dimensional object, reducing the print time of an object, improved efficiency and requires little manual intervention. While exemplary embodiments have been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist.
It should further be appreciated that the exemplary embodiments are only examples, and are not intended to limit the scope, applicability, operation, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements and method of operation described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.
It will be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects to be illustrative and not restrictive.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10201505849T | Jul 2015 | SG | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SG2016/050351 | 7/26/2016 | WO | 00 |
