Additive Manufacturing System for Three-Dimensional Printing

Abstract

There is provided a lighting system comprising a light source, and a cooling system with temperature sensing and responding capability coupled to the light source for maintaining a temperature of the light source within a defined variation from a set temperature. There are also provided a method of adjusting a temperature of a light source and a method of assembling the lighting system. There is further provided an additive manufacturing system for three-dimensional printing comprising the lighting system.

Claims

1. A lighting system comprising a light source, and a cooling system with temperature sensing and responding capability coupled to the light source for maintaining a temperature of the light source within a defined variation from a set temperature.

2. The light system of claim 1, wherein the light source is a light emitting diode (LED) array.

3. The light system of claim 1, wherein a power rating of the light source is in a range of about 30 watt to about 80 watt.

4. The light system of claim 1, further comprising a heat sink coupled to the light source.

5. The light system of claim 4, further comprising a thermally conductive adhesive which fills a gap between the light source and the heat sink.

6. The light system of claim 1, wherein the cooling system comprises: a temperature sensor; a controlling board configured to generate a command signal responsive to the temperature sensor; and a cooling means configured to cool the light source in response to the command signal.

7. The light system of claim 6, wherein the temperature sensor is coupled to the light source.

8. The light system of claim 6, wherein the light source and the temperature sensor are disposed on the heat sink and the temperature sensor detects the temperature of the heat sink.

9. The light system of claim 6, wherein the cooling means is an electronic fan.

10. A method of adjusting a temperature of a light source comprising the steps of a) sensing the temperature of the light source, and b) adjusting the operation of a cooling means of a cooling system with temperature sensing and responding capability coupled to the light source in response to a temperature change of the light source, whereby the temperature change is a temperature difference between the temperature sensed in step (a) and a set temperature of the light source.

11. The method of claim 10, wherein the set temperature is in a range of about 20° C. to about 40° C.

12. The method of claim 10, wherein step b) comprises a step of b1) operating the cooling means at a default cooling rate when the light source is turned on.

13. The method of claim 12, wherein step b) further comprises a step of b2) increasing the operation of the cooling means by a defined percentage for each degree Celsius temperature increase of the light source above the set temperature.

14. The method of claim 13, wherein the defined percentage is in a range of about 5% to about 30%.

15. The method of claim 13, wherein step b) further comprises a step of operating the cooling means at the default cooling rate or stopping the cooling means if the temperature of the light source is lower than the set temperature.

16. The method of claim 12, wherein the default cooling rate is in a range about 50 rpm to about 200 rpm.

17. A method of assembling a lighting system, comprising the steps of a) attaching a light source to a heat sink with a thermally conductive adhesive, and b) coupling a cooling system with temperature sensing and responding capability to the light source, the heat sink, or the thermally conductive adhesive, wherein the lighting system comprises the light source, and the cooling system with temperature sensing and responding capability coupled to the light source for maintaining a temperature of the light source within a defined variation from a set temperature.

18. The method of claim 17, wherein the cooling system is coupled to the light source, the heat sink, or the thermally conductive adhesive via a temperature sensor.

19. The method of claim 18, wherein the temperature sensor is further coupled to a controlling board and the controlling board is coupled to a cooling means responsive to a command signal generated by the controlling board.

20. An additive manufacturing system for three-dimensional printing comprising the lighting system of claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0094] FIG. 1 is a schematic diagram showing building of the self-feedback cooling system for a LED lighting source.

[0095] FIG. 2 is a graph showing the relationship between junction temperature and conversion efficiency of a LED light source.

[0096] FIG. 3 is a photo showing (A) the front side and (B) the back side images of the printer after fixing the ball screws.

[0097] FIG. 4 is a photo showing the building of the LED lighting source in a LED holder.

[0098] FIG. 5 is a schematic diagram in an exploded view showing the arrangement of some components of the three-dimensional printer.

[0099] FIG. 6 is a photo showing the built prototype of the three-dimensional printer.

[0100] FIG. 7 is a schematic diagram in a front-view of some components of the three-dimensional printer.

EXAMPLES

[0101] Non-limiting examples of the invention will be further described in greater detail by reference to specific Examples, which should not be construed as in any way limiting the scope of the invention.

Example 1: Assembly of the Lighting System with Self-Feedback Cooling System

[0102] To build the lighting system with self-feedback cooling system, several cooling technologies were integrated. The assembly of the lighting system with self-feedback cooling system is shown in FIG. 1. There was provided a heat sink 100. In Step 1, a thermally conductive adhesive 110 was coated onto the heat sink 100. In Step 2, a light source (such as a LED array) 120 was attached onto the thermally conductive adhesive 110. The heat sink can be used to quickly dissipate the heat generated from the LED array. Without the thermally conductive adhesive, air gap between the heat sink and the LED array may seriously affect heat conducting and the efficiency of heat dissipation because the high heat insulting property of air. Therefore, the thermally conductive adhesive was applied to fill the gap between the LED array and the heat sink.

[0103] In Step 3, a temperature sensor 130 was attached onto the thermally conductive adhesive 110. The temperature sensor can be a LM35 temperature sensor. In step 4, a cooling system 140 was built, which includes the temperature sensor 130, a controlling board 142 and a cooling means 144. The controlling board can be electronic controlling board. The cooling means can be an electronic fan. The cooling system 140 with temperature monitoring and self-feedback system as designed can provide a constant temperature for the light source 120.

[0104] In detail, the temperature sensor 130 can export a voltage signal to the controlling board 142. The controlling board can be a programmed Arduino controlling board. In the controlling board, a signal transmitter (such as a signal pin) was created and applied to an electronic switch (such as a transistor) 146. The signal pin can be applied to the base terminal of the transistor. Then a voltage signal was created by the transistor according to a circuit description defined by a G-code command. The cooling means 144 (such as an electric fan) operates at a default cooling rate when the light source 120 is turned on. If the temperature of the light source is higher than a set temperature (such as 25° C.), the controlling board will generate a 10% increase of the duty cycle for one more degree Celsius temperature increase of the light source. As a result, the fan will spin at a speed 10% faster for each degree Celsius temperature increase of the light source. If the temperature is lower than the set temperature (such as room temperature at 25° C.), the fan will stop or operate at the default cooling rate.

[0105] FIG. 2 shows the relationship between junction temperature and conversion efficiency of a LED light source 405 nm, 100 W. Light efficiency was measured by the Compact Power and Energy Meter Console with Standard Photodiode Power Sensor (Silicon, 200-1100 nm). The conversion efficiency as indicated by the relative light output decreased with the increase of the junction temperature. The solid line is the measurement data and the dash line is the fitting line. The set temperature range of 20° C. to 40° C. was optimized based on the light source to achieve a high conversion efficiency of about 100%. The fitting mean square error R.sup.2 indicates that there was a close match between actual values and the predicted/estimated values.

Example 2: Assembly of the Three-Dimensional Printer Prototype

[0106] Assembly of the three-dimensional printer prototype may include the following 11 steps:

Step 1. Frame Work Setting up

[0107] As shown in FIG. 3, aluminium profile 2020 was used to build a main frame work 310 of the three-dimensional printer. The front of the frame work was 310 mm. The depth of the frame work was 370 mm. The height of the frame work was 570 mm. The width of the frame work was 310 mm.

Step 2. Fixing the Ball Screw Component (with Step Motor) to the Frame Work

[0108] A linear guide 320 with a step motor 330 was fixed to the back side of the frame work using nails and screws. The linear guide can be a FUYU FLS linear guide. The step motor was set at the bottom of the linear guide as can be seen in FIG. 3.

[0109] FIG. 3A shows the front side image of the three-dimensional printer after fixing the ball screws and FIG. 3B shows the back side image of the three-dimensional printer after fixing the ball screws.

Step 3. Connecting the Step Motor to the Control Board

[0110] The step motor 330 was connected to an Arduino plate as control panel 630, which was used to control the z-axis moving of the step motor during printing.

Step 4. Building the LED Holder

[0111] As shown in FIG. 4, A LED holder 410 was built based on the dimension of the LED array, the cooling system and the frame work, by using aluminium profile and a wood plate. After that, the LED holder was fixed to the bottom of the frame work.

Step 5. Connecting the LED Array to LED Driver

[0112] The LED array was attached to the heat sink 100 with a layer of the thermally conductive adhesive, together with the self-feedback cooling system. Then the LED array was connected to a LED driver built together to the control panel 630. These items were fixed to the printer frame work as shown in FIG. 4.

Step 6. Building the Printer Power Supply

[0113] A 24-V DC power supply 420 was fixed to the frame work and the output of the power supplier was connected to the motor and the LED array separately.

Step 7. Building a LED Cover

[0114] Two pieces of aluminium plates were used to fold and build a LED cover for LED light protection and reflection. The built LED cover was fixed on the LED holder, with the bottom attached to the LED array and the top directly connected to a LCD holder.

Step 8. Building the LCD Holder

[0115] A schematic diagram is shown in FIG. 5 to illustrate some of the components of the three-dimensional printer. A condense lens 540 was placed on top of the high power LED array 120 to diverge the light from the LED array. Another lens (such as a Fresnel lens) 530 was used in between the condenser lens 540 and a LCD screen 520 for further directing the light from the LED array. A printing tray (vat) 510 was placed on top of the LCD screen 520 for holding the polymer solution for three-dimensional printing.

[0116] FIG. 6 shows a photo of a built prototype of the three-dimensional printer and FIG. 7 shows a schematic diagram in a front-view of some of the components of the three-dimensional printer.

[0117] One transparent PMMA plate 610 was cut with a size similar to the dimension of a LCD screen 520. Then, one wood plate 620 was cut, which can hold the cut PMMA plate 610. The wood plate 620 was fixed to the main frame work 310 at a distance of several centimetres from the LED array.

Step 9. Setting up the LCD Screen

[0118] The LCD screen 520 was placed on the transparent holding PMMA plate 610, which was then placed in a target position. The LCD screen 520 was then connected to its controller.

Step 10. Setting up the Printing Tray and Platform

[0119] A printing tray 510 was fixed on top of the LCD screen 520 and a printing platform was built onto a gliding block. To protect LCD screen 520 from the wrong operation, an end-stop switch 640 was connected to its motor control board.

Step 11. Checking the Power Supply and Connectors

[0120] It was checked if all the driver are correctly connected to the power supply and if the LED array 120, the LCD screen 520 and the motors were correctly connected to their corresponding drivers/controllers.

[0121] Step 12. Connecting to a Control Computer

[0122] (1) A LCD controller board was connected to a computer with the printing software through HDMI cable.

[0123] (2) The motor controller (the Arduino board) was connected to the computer through USB cable or bluetooth serial module.

[0124] (3) Micromake software was opened and a configuration file was imported. Step 13. Testing

[0125] (1) One printing demo STL file was loaded to the computer.

[0126] (2) Slicing was performed on the computer and an order was sent to the printer.

[0127] (3) A printing test was performed.

[0128] For the three-dimensional printer prototype as built above, the temperature of the LED array is monitored by the temperature sensor which controls the speed of the electronic fan through an electronics platform with the self-feedback cooling system. In this way, a high power of light source can be used in the system with steady performance. Combining with the high resolution of the LCD display and fast motor system, a LCD-display based printing process and a printer prototype are provided with high printing resolution and faster printing speed. The built prototype shows a resolution of 2560×1600 pixel, with a printing speed of 3 second/layer for normal resin by using a 50-watt LED light source.

INDUSTRIAL APPLICABILITY

[0129] The disclosed lighting system and methods may be used in an additive manufacturing system for maintaining the stability of the light source at a high power. Therefore, the additive manufacturing system can be used to manufacture various products with fast printing speed and high resolution, which are applicable for a wide range of industrial sectors, such as healthcare industry.

[0130] It will be apparent that various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims.