Method and apparatus for improved surface solidification of three-dimensional printed parts

Abstract

Methods for curing a three-dimensional (3D) printed part are disclosed. For example, the method includes: adding a layer of build material; curing the layer of build material using a first light source having a first wavelength; repeating the adding and curing using the light source having the first wavelength to a predetermined number of layers; adding a final top layer of build material to form the 3D printed part; and curing the final top layer of build material using a second light source having a second wavelength different from the first wavelength.

Description

[0001] This application is a continuation-in-part of application number 201810296575.0, filed on March 30, 2018, entitled “Method and Apparatus for Improved Surface Solidification of Three-Dimensional Printed Parts.” TECHNICAL FIELD

[0002] The present disclosure relates generally to three-dimensional (3D) printing, and more specifically, to a method and apparatus for improved surface solidification of 3D printed parts. BACKGROUND

[0003] Additive printing, also known as 3D printing, has become an innovative manufacturing technology. 3D printing brings unprecedented benefits to manufacturers, such as reduced production costs and accelerated development and customization.

[0004] 3D printing operates by adding layers of build material according to the profile or shape of the printed part. For example, the layer can be solidified by a UV solidification light. The process of adding build material and solidification can be repeated layer by layer until the printed part is complete. The printing can be controlled by a computer. SUMMARY

[0005] According to aspects shown herein, a method, non-transitory computer readable medium, and apparatus for solidifying a three-dimensional (3D) printed part are provided. One disclosed feature of embodiments is a method that adds a layer of build material; solidifies the layer of build material using a first light source having a first wavelength; repeats the adding and solidifying using the first light source having the first wavelength to a predetermined number of layers; adds a final top layer of build material to form the 3D printed part; and solidifies the final top layer of build material using a second light source having a second wavelength different from the first wavelength.

[0006] Another disclosed feature of embodiments is a non-transitory computer readable medium having stored thereon a plurality of instructions that, when executed by a processor, cause the processor to: add a layer of build material; solidify the layer of build material using a first light source having a first wavelength; repeat the adding and solidifying using the first light source having the first wavelength to a predetermined number of layers; add a final top layer of build material to form the 3D printed part; and solidify the final top layer of build material using a second light source having a second wavelength different from the first wavelength.

[0007] Another disclosed feature of embodiments is an apparatus comprising a processor and a computer readable medium storing a plurality of instructions that, when executed by the processor, cause the processor to: add a layer of build material; cure the layer of build material using a first light source having a first wavelength; repeat the adding and curing using the first light source having the first wavelength to a predetermined number of layers; add a final top layer of build material to form a 3D printed part; and cure the final top layer of build material using a second light source having a second wavelength different from the first wavelength. BRIEF DESCRIPTION OF DRAWINGS

[0008] The teachings of the disclosure can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which: Figure 1 A block diagram of an example 3D printer of the present disclosure is shown; Figure 2 An example graph showing a percentage of strength versus a percentage of remaining uncured build material is shown; Figure 3 A flowchart of an example method for curing a 3D printed part is shown; and Figure 4 A high-level block diagram of an example computer suitable for performing the functions described herein is shown.

[0009] To facilitate an understanding of this disclosure, like reference numerals have been used, where possible, to designate identical elements that are common to the figures. DETAILED DESCRIPTION

[0010] The present disclosure broadly discloses methods and apparatus for improved surface curing of 3D printed parts. As discussed above, 3D printing operates by adding layers of build material according to the profile or shape of the printed part. The layer can be cured, for example, by ultraviolet curing light. The process of adding build material and curing can be repeated layer by layer until the printed part is complete. The printing can be controlled by a computer.

[0011] In conventional 3D printing, the bottom layers can undergo sufficient oxygen inhibition to fully cure the bottom layers. However, the top layers can remain only partially cured, resulting in a tacky surface or a sticky surface with an unpleasant odor. One solution can be to add a sacrificial layer on top of or on the top layers. The sacrificial layer can be added and cured to ensure that the top layers are fully cured. Subsequently, the sacrificial layer can be removed. However, this can increase the printing cost due to the additional material for the sacrificial layer and the energy for the additional curing. In addition, using a sacrificial layer can increase the processing time due to the additional printing step, the step of removing the sacrificial layer, and the step of cleaning the top layers. Another disadvantage of using a sacrificial layer is that the top layers can only have a rough finish.

[0012] Embodiments of the present disclosure provide a novel method for improved surface solidification of a top layer of a 3D printed part. The method of the present disclosure uses a combination of different wavelengths of light for solidification without the use of a sacrificial layer. Thus, embodiments of the present disclosure ensure that the top layer is fully solidified and can provide a smooth finish to the top layer.

[0013] Figure 1 An example 3D printer 100 of the present disclosure is shown. In one embodiment, the 3D printer 100 can include a processor 102 and a computer readable medium 104. The computer readable medium 104 can store instructions and stored parameters related to a print job. The processor can execute the instructions and use the stored parameters to perform the functions described herein. In one embodiment, the processor 102 and the computer readable medium 104 can be part of separate computer systems that execute a computer aided design (CAD) program that controls the 3D printer 100.

[0014] In one embodiment, the 3D printer 100 can include a dispenser 106 that dispenses a build material 108, a first light source 110, a second light source 112, and a movable platform 114. In one embodiment, the build material 108 can be a solidifiable material. For example, the build material 108 can be small particles of a metal, a plastic, a polymer, or an ultraviolet (UV) solidifiable ink.

[0015] In one embodiment, when the build material 108 is a UV solidifiable ink, the 3D printer 100 can include multiple dispensers 106 for each of multiple different colors. For example, the UV solidifiable ink can be different colors, such as cyan, magenta, yellow, and black, and the 3D printer 100 can include a corresponding dispenser 106 for each color.

[0016] In one embodiment, the first light source 110 and the second light source 112 can be UV light sources that operate at different wavelengths. For example, the first light source 110 can be a UV light source that operates between approximately 390 nanometers (nm) and 400 nm. In one embodiment, the first light source 110 can operate at 395 nm.

[0017] In one embodiment, the second light source 112 can be a UV light source that operates between approximately 360 nm and 370 nm. In one embodiment, the second light source 112 can operate at 365 nm.

[0018] The first light source 110 and the second light source 112 can operate at different light intensity levels at the respective wavelengths of light. For example, the first light source 110 and the second light source 112 can operate at anywhere from 15% of the normal operating light intensity value to 200% of the normal operating light intensity value.

[0019] In one embodiment, build material 108 may be dispensed onto a movable platform 114 to lay a first layer 1161 of build material 108. The movable platform 114 may be movable along a two-dimensional axis below the dispenser 106, or the dispenser 106 may be movable along a two-dimensional axis above the platform 114. The build material 108 may be dispensed according to the shape or profile of a particular 3D printed part stored in a computer-readable medium 104 and dispensed by a processor 102.

[0020] In another embodiment, the movable platform 114 may include a bed of build material 108. The outline of the 3D printed part can be "printed" onto the bed of build material 108 using a curable adhesive or liquid. The build material 108 can be dispensed onto the top of the "printed" layer after the "printed" layer has cured.

[0021] The movable platform 114 can then move the first layer 1161 under the first light source 110. The first layer 1161 can be exposed to light from the first light source 110 for a predetermined amount of time (e.g., a few seconds or minutes) to cure the building material 108 of the first layer 1161. This process can be repeated until layer 116 is reached. n-1 (For example, the last top layer 116) n Previously or at the last top floor 116 n The predetermined number of layers (adjacent layers).

[0022] Up to floor 116 n-1 After the predetermined number of layers have cured, the final top layer 116 can be allocated. n The movable platform 114 can move layers 1161 to 116 under the second light source 112. n The stacking. The final top layer is 116. n The final top layer 116 can be cured under the second light source 112 for a predetermined amount of time (e.g., a few seconds or a few minutes). n The building material 108. In some embodiments, the movable platform 114 can move the final top layer 116 under the second light source 112. n It passed several times.

[0023] Therefore, it includes multiple layers 1161 to 116 n The 3D parts can be finished and have a smooth finish. Notably, no sacrificial layer is applied to the final layer 116. n It is then cured and removed. Additionally, it should be noted that layers 1161 to 116... n-1 Only exposed to the first light source 110, and the last top layer 116 n Exposed only to the second light source 112. Layers 1161 to 116 n-1 Using a first light source with a first wavelength, and the last top layer 116n Using a second light source 112 at a second wavelength different from the first wavelength allows the 3D part to have a smooth finish without the need for a sacrificial layer or using excess energy or light.

[0024] Only the last top layer 116 n Another advantage of using a second wavelength can be that when another layer 116 is added, the intermediate layers (e.g., layers 1161through 116 n-1 ) can not fully cure. This can give better interlayer adhesion, resulting in a part with better structural integrity.

[0025] Figure 2 A graph 200 is shown that illustrates the advantages of using two different wavelengths to cure a 3D part. The x-axis 210 represents the light intensity percentage of the light source used. The y-axis 212 represents the percentage of uncured build material. In one embodiment, to determine whether a 3D part is fully cured, the complete 3D part can be weighed, then placed in a solution of tetrahydrofuran (THF). THF can bind to any remaining uncured build material in the 3D part.

[0026] The 3D part can be removed from the THF after 24 hours and placed on an aluminum pan and allowed to air dry at 75 degrees Celsius (°C) for 24 hours to dry the sample. The dried 3D part can then be weighed to determine the weight loss from the initial weight of the 3D part. Uncured build material can be determined based on the percentage calculated from the weight loss of the 3D part divided by the initial weight multiplied by 100. A fully cured 3D part can have a percentage that is 8 or less.

[0027] Figure 2 A first line 202 is shown that represents a 3D part cured using only a single light source at 395 nm. At lower light intensities (e.g., around 15%), the completed 3D part remains uncured (e.g., has a percentage over 30%). Even with higher intensity light output at 395 nm, the 3D part does not fully cure, as shown by the four data points on line 202.

[0028] A second line 204 represents a 3D part cured using only a single light source at 365 nm. At lower light intensities (e.g., around 15%), the completed 3D part remains uncured (e.g., has a percentage over 25%). When using a light source at 365 nm at light intensities from 100% to 200%, the 3D part can become fully cured, as shown by the data points on line 204.

[0029] A third line 206 represents a 3D part cured using an embodiment of the present disclosure. For example, for the penultimate layer (e.g., layer 116 n-1of approximately 395 nm. The last layer (e.g., the final top layer 116) can then be cured using a second light source 112 of approximately 365 nm n As shown by the third line 206, the 3D part can become fully cured (e.g., with a percentage of approximately 8 or less) even when the 395 nm light and the 365 nm light are emitted at intensities as low as 15%. Increasing the intensity does not significantly increase the amount of curing, as shown by the third line 206.

[0030] The fourth line 208 represents curing the 3D part using a first light source 110 of approximately 395 nm and a second light source 112 of approximately 365 nm for each layer. In other words, each layer is cured with a combination of light emitted at 395 nm and 365 nm. The fourth line 208 shows that the 3D part can be fully cured (e.g., with a percentage of approximately 8 or less) even when the 395 nm light and the 365 nm light are emitted in combination at intensities as low as 15%. However, it should be noted that the improvement in curing does not substantially exceed the improvement in curing of the final top layer 116 n using a second light source 112 of approximately 365 nm, as shown by the line 206.

[0031] Notably, operating the second light source 112 at approximately 365 nm is significantly more expensive than operating the first light source 110 at approximately 395 nm. Accordingly, embodiments of the present disclosure provide a method that fully cures a 3D printed part while minimizing the use of the second light source 112 operating at approximately 365 nm. Additionally, using embodiments of the present disclosure, a 3D printed part can be fully cured at lower light intensities, which can also result in additional efficiencies and cost savings.

[0032] Referring back to Figure 1 it should be noted that Figure 1 has been simplified for ease of explanation. For example, Figure 1 The 3D printer 100 in may include additional components and devices not shown. Additionally, the 3D printer 100 provides only one mechanical implementation of the present disclosure. For example, although the movable platform 114 is shown as moving horizontally left and right, the 3D printer 100 can be arranged vertically such that the movable platform 114 moves vertically up and down. In another example, the movable platform 114 can be stationary and the dispenser 106, the first light source 110, and the second light source 112 can move over the build material 108.

[0033] Figure 3A flowchart of an example method 300 for solidifying a 3D printed part is shown. In one embodiment, one or more steps or operations of the method 300 can be performed by the 3D printer 100 or a computer controlling the operation of the 3D printer 100, as shown and discussed below. Figure 4

[0034] The method 300 begins at block 302. At block 304, the method 300 adds a layer of build material. The build material can be small particles of a solidifiable material, such as metal, plastic, polymer, or UV solidifiable ink. The layer of build material can be added by a dispenser, or can be“printed” using a solidifiable liquid or binder that is applied to a bed of build material in the shape of the 3D printed part.

[0035] At block 306, the method 300 solidifies the layer of build material using a first light source having a first wavelength. For example, the first light source can be a UV light source operating between 390 nanometers (nm) and 400 nm. In one embodiment, the first light source can operate at 395 nm. In one embodiment, the first light source can operate at a light intensity that is less than a full intensity level. For example, the first light source can operate at approximately 15 percent to 50 percent of the full intensity level.

[0036] At block 308, the method 300 determines whether a predetermined number of layers has been reached. In one embodiment, the predetermined number of layers can be one less than the total number of layers. For example, if the 3D printed part has 20 layers, the predetermined number of layers can be 19.

[0037] If the answer is no, the method 300 can return to block 304 and blocks 304-306 can be repeated. If the answer to block 308 is yes, the method 300 can proceed to block 310.

[0038] At block 310, the method 300 adds a final top layer of build material to form the 3D printed part. It should be noted that the method 300 does not use sacrificial layers in addition to the final top layer that is solidified and removed. The final top layer can be the actual top layer of the 3D printed part.

[0039] At block 312, the method 300 solidifies the final top layer of build material using a second light source having a second wavelength that is different than the first wavelength. For example, the second light source can be a UV light source operating between 360 nm and 370 nm. In one embodiment, the second light source can operate at 365 nm. In one embodiment, the second light source can operate at a light intensity that is less than a full intensity level. For example, the second light source can operate at approximately 15 percent to 50 percent of the full intensity level.

[0040] ​At block 314, the method 300 determines whether additional passes under the second light source are needed. For example, some processes can use multiple passes under the second light source for the final top layer to ensure the top layer is fully cured.

[0041] If the answer is yes, the method 300 can return to block 312 and blocks 312 and 314 can be repeated. If the answer to block 314 is no, the method 300 can proceed to block 316.

[0042] Thus, the method 300 of the present disclosure provides 3D printed parts with smooth finishes. Additionally, the method 300 does not use cured and removed sacrificial layers to ensure full curing of the 3D printed parts. Furthermore, the method 300 uses a combination of different wavelengths of light at different layers to ensure full curing without the use of excess energy or light. This results in a more efficient process, which can also be cheaper due to less energy and material costs. At block 316, the method 300 ends.

[0043] It should be noted that, Figure 3 Blocks in the method 300 described above that determine operations or involve decisions do not necessarily require practicing both branches of the determining operation. In other words, one of the branches of the determining operation can be considered an optional step. Additionally, one or more steps, blocks, functions, or operations of the method 300 described above can include optional steps, or can be combined, separated, and / or performed in a different order than described above, without departing from example embodiments of the present disclosure.

[0044] Figure 4 A high-level block diagram of a computer dedicated to performing the functions described herein is depicted. As Figure 4As shown, computer 400 includes one or more hardware processor elements 402 (e.g., central processing units (CPUs), microprocessors, or multi-core processors), memory 404 (e.g., random access memory (RAM) and / or read only memory (ROM)), a module 405 for solidifying 3D printed parts, and various input / output devices 406 (e.g., storage devices including, but not limited to, magnetic disk drives, floppy disk drives, hard drives, or optical disk drives; receivers, transmitters, speakers, displays, voice synthesizers, output ports, input ports, and user input devices such as keyboards, keypads, mice, microphones, etc.). Although only one processor element is shown, it should be noted that more than one processor element can be employed according to the needs of a particular illustrative example. In addition, although only one computer is shown, if the methods as discussed above are implemented in a distributed or parallel manner, the computer shown in the figure can be one of more than one computer, which can be functioning as a distributed or parallel computer. Furthermore, one or more hardware processors can be used to support virtualization or shared computing environments. Virtualization computing environments can support one or more virtual machines that represent computers, servers, or other computing devices. In such virtualized virtual machines, hardware components such as hardware processors and computer-readable storage devices can be virtualized or logically represented.

[0045] It should be noted that the present disclosure can be implemented in software and / or in a combination of software and hardware, e.g., using custom- made integrated circuits (ASICs), programmable logic arrays (PLAs), including field-programmable gate arrays (FPGAs), or state machines, and / or using computers or any other hardware equivalents. The present disclosure can be implemented in one or more computer programs executing on one or more computer systems or processors as discussed above, or interleaved or shared across multiple hardware or software platforms. Furthermore, the disclosure can be implemented as programmed software or in hardware, firmware, or any combination thereof. In one embodiment, instructions and data for the module or process 405 for solidifying 3D printed parts (e.g., software programs including computer executable instructions) can be loaded into memory 404 and executed by hardware processor element 402 to implement the steps, functions or operations as discussed in connection with the illustrative examples above. Additionally, the hardware processor element 402 can be one of more than one hardware processors, such as a plurality of processors 402-1, 402-2, etc. working in concert or in succession to implement the methods disclosed herein. Furthermore, "hardware processor" or "hardware processors" can also be understood to encompass a hardware logic circuit, such as a state machine, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other hardware logic circuits, which are designed to implement (or to facilitate, direct or cooperate with another hardware device or component to implement) the steps, functions, and / or operations of the methods disclosed above.

[0046] A processor executing computer-readable or software instructions related to the above-described methods can be viewed as programmed or special purpose processors. As such, the present module 405 for solidifying 3D printed parts of the present disclosure (including related data structures) can be stored on tangible or physical (broadly non-transitory) computer-readable storage devices or media, such as volatile memory, non-volatile memory, ROM memory, RAM memory, magnetic or optical drives or disks, devices or diskettes, etc. More specifically, the computer-readable storage devices can include any physical device which provides the ability to store information such as data and / or instructions for access by a processor or computing device such as a computer or application server.

[0047] It is to be appreciated that the variations disclosed above, as well as other features and functions, or alternatives thereof, can be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements can be made by those skilled in the art having the benefit of this disclosure. Such equivalents are intended to be encompassed by the described claims.

Claims

1. A method for curing a three-dimensional (3D) printed part, the method comprising: Add layers of building materials; The layer of the building material is cured using a first light source having a first wavelength; Repeat the addition and curing with a first light source having a first wavelength to achieve a predetermined number of layers; The final layer of the building material is added to form the 3D printed part; and The final layer of the building material is cured using a second light source with a second wavelength different from the first wavelength.

2. The method of claim 1, wherein the building material comprises a UV-curable ink.

3. The method according to claim 1, wherein the first light source comprises ultraviolet (UV) light.

4. The method of claim 3, wherein the first wavelength is contained in the range of 390 nanometers (nm) and 400 nm.

5. The method of claim 4, wherein the first light source is powered at a level less than full intensity.

6. A non-transient computer-readable medium storing a plurality of instructions, which, when executed by a processor, cause the processor to perform operations for curing a three-dimensional (3D) printed part, the operations including: Add layers of building materials; The layer of the building material is cured using a first light source having a first wavelength; Repeat the addition and curing with a first light source having a first wavelength to achieve a predetermined number of layers; The final layer of the building material is added to form the 3D printed part; and The final layer of the building material is cured using a second light source with a second wavelength different from the first wavelength.

7. The non-transient computer-readable medium of claim 6, wherein the building material comprises a UV-curable ink.

8. The non-transient computer-readable medium of claim 6, wherein the first light source comprises ultraviolet (UV) light, and the first wavelength comprises a wavelength between 390 nanometers (nm) and 400 nm.

9. The non-transient computer-readable medium of claim 8, wherein the first light source is powered at a level less than full intensity.

10. A method for curing a three-dimensional (3D) printed part, the method comprising: Add a layer of UV-curable ink; The UV-curable ink layer is cured using a first UV light source between approximately 390 nanometers (nm) and 400 nm. Repeat the addition and curing process at approximately 390 nm to 400 nm to achieve the predetermined number of layers; The final layer of the UV-curable ink is added to form the 3D printed part; and The final layer of the UV-curable ink is cured using a second UV light source between approximately 360 nm and 370 nm to provide a smooth finish on the final layer of the UV-curable ink.

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