3D PRINTING METHOD AND SYSTEM USING NEAR-INFRARED SEMICONDUCTOR LASER AS HEATING SOURCE

Abstract

Provided is a 3D printing method and system using a near-infrared semiconductor laser as a heating source. The 3D printing system includes a printing spray head (4). In the 3D printing process, a laser beam is output by the near-infrared semiconductor laser to form a laser spot, which scans in an arbitrary path to cover a relevant area of a printed material for in-situ heating, thereby realizing the “asynchronous” printing mode. The near-infrared laser has higher penetration depth compared with a mid-infrared laser, so that the printing method using a near-infrared semiconductor laser as a heating source can be flexibly compatible with various printing platforms and the working process of the laser in the formed printing system can be decoupled from the 3D printing process of an article.

Claims

1. A 3D printing method, characterized in that a near-infrared semiconductor laser is used as a heating source, that is, a laser beam generated by the laser is used for in-situ heating of an article in a 3D printing process.

2. The method according to claim 1, wherein the method employs a 3D printing device using a near-infrared semiconductor laser as a heating source to perform the 3D printing in an “asynchronous” mode; preferably, the 3D printing device comprises a printing head; in the 3D printing process, the laser beam (such as a collimated beam) is output by the near-infrared semiconductor laser to form a laser spot, which scans in an arbitrary path to cover a relevant area of a printed material for in-situ heating, thereby realizing “asynchronous” printing mode.

3. The method according to claim 1, wherein the method comprises: performing 3D printing by using a 3D printing device with the near-infrared semiconductor laser as the heating source, wherein in the printing process, the laser output by the near-infrared semiconductor laser realizes flexible optical fiber transmission through spatial coupling, and a collimated beam is output through an optical fiber head beam shaping system of the near-infrared semiconductor laser to form a laser spot, which scans in an arbitrary path to cover a relevant area of the printed material for in-situ heating of an article, thereby realizing “asynchronous” printing mode in the 3D printing process.

4. The method according to claim 1, wherein the method comprises: performing 3D printing by using a 3D printing device with the near-infrared semiconductor laser as the heating source, wherein in the printing process, the near-infrared semiconductor laser and a printing head are separately controlled by double tracks, and the printing head is used to print single-layer or multi-layer materials. The laser output by the near-infrared semiconductor laser realizes flexible optical fiber transmission through spatial coupling, and a collimated beam is output by an optical fiber head beam shaping system of the near-infrared semiconductor laser to form a laser spot, which scans in an arbitrary path to cover a relevant area of the printed material for in-situ heating. The process is repeated for multiple times to realize “double-track asynchronous” printing mode of an article in the 3D printing process.

5. The method according to claim 1, wherein the method comprises: performing 3D printing by using a 3D printing device with the near-infrared semiconductor laser as the heating source, wherein in the printing process, the near-infrared semiconductor laser and a printing head are controlled by the same track and first the printing head is used to print single-layer or multi-layer materials; then the printing is suspended, and the laser output by the near-infrared semiconductor laser realizes flexible optical fiber transmission through spatial coupling, and a collimated beam is output by an optical fiber head beam shaping system of the near-infrared semiconductor laser to form a laser spot, which scans in an arbitrary path to cover a relevant area of the printed material for in-situ heating. The process is repeated for multiple times to realize “same-track asynchronous” printing mode of an article in the 3D printing process.

6. The method according to claim 1, wherein the near-infrared semiconductor laser comprises a flexible optical fiber and an optical fiber head beam shaping system, wherein the optical fiber head beam shaping system comprises a beam collimating mirror and an adjustable attenuator, and the laser emitted by the near-infrared semiconductor laser is transmitted by the flexible optical fiber and is output from the adjustable attenuator after being collimated by the beam collimating mirror; the adjustable attenuator is used for adjusting the power density of the output laser.

7. The method according to claim 6, wherein the near-infrared semiconductor laser further comprises a focusing system comprising a converging mirror disposed between the beam collimating mirror and the adjustable attenuator.

8. The method according to claim 1, wherein an output wavelength of the near-infrared semiconductor laser is 780-2500 nm; and/or a power density of the near-infrared semiconductor laser is 0.1-10 kW/cm.sup.2; and/or a size of the spot formed by the near-infrared semiconductor laser is 1-1000 mm.sup.2; and/or a moving speed of the near-infrared semiconductor laser is 0.5-5 mm/s; and/or a moving speed of the printing head of the 3D printing device is 10-40 mm/s.

9. The method according to claim 1, wherein the 3D printing includes powder bed selective laser sintering (SLS) 3D printing, jet printing, direct ink writing (DIW) 3D printing or fused deposition modeling (FDM) 3D printing.

10. A 3D printing system, wherein the 3D printing system is used for implementing the method according to claim 1 and comprises a 3D printing device, a near-infrared semiconductor laser and a track, wherein the 3D printing device comprises a printing head; the near-infrared semiconductor laser comprises a flexible optical fiber and an optical fiber head beam shaping system, wherein the optical fiber head beam shaping system comprises a beam collimating mirror and an adjustable attenuator, and the laser emitted by the near-infrared semiconductor laser is transmitted by the flexible optical fiber and is output from the adjustable attenuator after being collimated by the beam collimating mirror; the printing head and the near-infrared semiconductor laser are arranged on the same track or different tracks; preferably, the near-infrared semiconductor laser further comprises a focusing system comprising a converging mirror disposed between the beam collimating mirror and the adjustable attenuator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] FIG. 1 shows a schematic diagram of same-track asynchronous control of the semiconductor laser and an extrusion 3D printer;

[0052] FIG. 2 shows a schematic diagram of double-track asynchronous control of the semiconductor laser and an extrusion 3D printer;

[0053] FIG. 3 shows an optical photograph of the bottom of a 1 mm article before and after laser treatment by the semiconductor laser in the same-track asynchronous mode;

[0054] FIG. 4 shows a scanning electron micrograph of heating process of the printed material by the semiconductor laser in the same-track asynchronous mode;

[0055] FIG. 5 shows the diagram of differential scanning calorimetry analysis before and after laser treatment of the printed material in the same-track asynchronous mode; and

[0056] FIG. 6 shows a diagram of mechanical tensile test results before and after laser treatment of the printed material in the same-track asynchronous mode.

[0057] In FIGS. 1 and 2, 1 is a raw material filament, 2 is a sampler, 3 is a heating cylinder, 4 is a printing spray head, 5 is a first slide block, 6 is a first guide rail, 7 is a printing platform, 8 is a flexible quartz optical fiber, 9 is a detachable bracket, 10 is an optical fiber head beam shaping system, 11 is a beam collimating mirror, 12 is an adjustable attenuator, 13 is a second guide rail, and 14 is a second slide block.

DETAILED DESCRIPTION

[0058] The preparation method of the present invention will be further illustrated in detail with reference to the following specific examples. It should be understood that the following examples are merely exemplary illustration and explanation of the present invention, and should not be construed as limiting the protection scope of the present invention. All techniques implemented based on the above-mentioned contents of the present invention are encompassed within the protection scope of the present invention.

[0059] Unless otherwise stated, the experimental methods used in the following examples are conventional methods. Unless otherwise stated, the reagents, materials, and the like used in the following examples are commercially available.

[0060] Instruments and Materials:

[0061] Polyetheretherketone filament (PEEK, available from Jilin JUSEP Special Plastics Co., Ltd.); experimental instruments comprise a desktop FDM 3D printer and an 808 nm near-infrared semiconductor laser; characterization instruments comprise a scanning electron microscope (JEOL JSM-7500F), a differential scanning calorimeter (TA Q-2000) and a universal tensile testing machine (UTM-16555, available from Shenzhen Suns Technology Stock Co., Ltd.).

[0062] The surface and cross section of the prepared sample are morphologically analyzed using a scanning electron microscope (SEM). The scanning electron microscope scans the surface of the sample through a tiny electron beam, and the secondary electrons generated in the scanning process are collected by a special detector. An electric signal is formed and then transmitted to the end of the image tube, then a three-dimensional structure of the surface of the object is displayed on a screen, and a computer is used for photographing. In this example, the ultra-high-resolution cold-field-emission scanning electron microscope JEOL JSM-7500F is employed with a accelerating voltage of 5 kV.

[0063] The processing thermal history of the prepared sample is analyzed by employing the differential scanning calorimeter (DSC) based on a power compensation principle of heat absorption and emission of material.

Example 1

[0064] As shown in FIG. 1, a same-track asynchronous-controlled 3D printing system was provided, wherein a raw material filament 1 was fed into a heating cylinder 3 through a sampler 2, and a three-dimensional pattern was deposited layer by layer on a printing platform 7 through a printing spray head 4 under the three-axis movement of a first slide block 5 and a first guide rail 6; an optical fiber head beam shaping system 10 of a semiconductor laser was mounted on one side of the printing spray head 4 through a detachable bracket 9, so as to ensure that the output beam of the optical fiber head beam shaping system 10 can be accurately irradiated to a discharging position of the printing spray head 4, so that the output light can cover a fused deposition printing range of the original polymer material under the guidance of the movement of the first slide block 5, and meanwhile, the optical fiber head beam shaping system 10 of the semiconductor laser and the printing spray head 4 shared the first guide rail 6, resulting in vertical movement of the optical fiber head beam shaping system 10. The optical fiber head beam shaping system 10 comprised a beam collimating mirror 11 and an adjustable attenuator 12, which were used for collimating, converging and shaping the near-infrared laser transmitted by the flexible quartz optical fiber 8 and adjusting the power density.

[0065] In the printing process, after a single-layer or multi-layer polymer material was printed by using a slicing software, the sampler 2 stopped working, and then the first slide block 5 was started to guide the optical fiber head beam shaping system 10 to scan a printed area in an arbitrary path at a linear velocity of 1 mm/s for in-situ heating, thereby realizing the “same-track asynchronous” printing mode.

Example 2

[0066] As shown in FIG. 2, a double-track asynchronously-controlled 3D printing system was provided, wherein an optical fiber head beam shaping system 10 of a semiconductor laser was mounted on a second slide block 14 through a second guide rail 13; a printing spray head 4 was mounted on a first guide rail 6 through a first slide block 5. The first slide block 5 and the second slide block 14 had the same function and both can move in a plane; the first guide rail 6 and the second guide rail 13 had the same function and both can move vertically.

[0067] In the printing process, after a single-layer or multi-layer polymer material was printed by the printing spray head 4, the second guide rail 13 and the second slide block 14 were controlled by a slicing software to guide the laser to scan a printed area in an arbitrary path at a linear velocity of 1 mm/s for in-situ heating, thereby realizing the “double-track asynchronous” printing mode.

Test Example 1

[0068] The annealing effect of the printed material with single-layer, double-layer or five-layer deposition thickness after in-situ heating with the semiconductor laser, the interface bonding strength among filaments of a printed article and the enhancement effect of the macroscopic mechanical property in the same-track asynchronous control mode of Example 1 and in the double-track asynchronous control mode of Example 2 were tested.

[0069] The geometrical parameters and laser processing conditions of the processed FDM-printed articles are shown in the following table.

TABLE-US-00001 Type of article Shape Thickness Laser condition Single- Rectangle, 1 cm × 0.4 mm Collimated beam, circular spot, layer 5 cm power density 2.0 kW/cm.sup.2 Double- Rectangle, 1 cm × 0.6 mm Collimated beam, circular spot, layer 5 cm power density 2.0 kW/cm.sup.2 Five-layer Rectangle, 1 cm ×   1 mm Collimated beam, circular spot, 5 cm power density 3.0 kW/cm.sup.2

[0070] Referring to FIG. 3, compared with an original FDM-printed sample strip with the same five-layer deposition thickness, the printed sample strip which was heated in situ by using an 808 nm semiconductor laser at an output power density of 3.0 kW/cm′ in two control modes (same-track asynchronous mode in Example 1 and double-track asynchronous mode in Example 2) had an obviously whitish color at its bottom, and the whole article had volume shrinkage, which showed that the 1 mm thickness of the article had no influence on the in-situ heating of the whole article with the 808 nm semiconductor laser, indicating that the 808 nm semiconductor laser had higher penetration depth.

[0071] Referring to FIG. 4, a and b in the scanning electron micrograph (FIG. 4) showed that after heated in situ by the 808 nm semiconductor laser in two control modes, the single-layer printed sample strip exhibited interface fusion of melt-extruded filaments in an in-plane direction (x-y plane), which indicates that the in-situ heating using the 808 nm semiconductor laser in the two control modes had an obvious enhancement effect on the interface bonding strength of the 3D printing extruded filaments, and the influence of weak interface bonding strength among FDM-printed filaments on the macroscopic mechanical property can be weakened.

[0072] Referring to FIG. 5, after the printed articles with single-layer, double-layer or five-layer deposition thickness were heated in-situ by using the 808 nm semiconductor laser in two control modes, secondary crystallization peaks of printed articles of all deposition thickness at about 173° C. disappeared, i.e. realizing annealing treatment. By integrating the exothermic peaks around the temperature, the annealing efficiency of the single-layer and double-layer printed articles was 100% and the annealing efficiency of the five-layer printed article was 98.7%, which indicated that the crystallinity of all articles was improved after in-situ heating and tended to the intrinsic value of the material, further resulting in whitening of the articles caused by the enhanced birefringence phenomenon and volume shrinkage caused by the increase of density, which is consistent with the macroscopic phenomenon described in FIG. 3.

[0073] Referring to a-c in FIG. 6, after in-situ heating using the 808 nm semiconductor laser in two control modes, in addition to the qualitative phenomenon of whitening, volume shrinkage and the improvement of mechanical properties such as the enhancement of interface bonding strength, tensile mechanical tests showed that the overall tensile breaking strength of all articles after in-situ heating was improved by about 30%. Compared with the sample strip without in-situ heating, the single-layer sample strip had an increased tensile breaking strength from 37 MPa to 49 MPa, an increase of 32.4%; the double-layer sample strip had an increased tensile breaking strength from 35 MPa to 43 MPa, an increase of 23.0%; the five-layer sample strip had an increased tensile breaking strength from 41 MPa to 52 MPa, an increase of 27.0%.

[0074] The results showed that through in-situ heating of the FDM-printed articles by using the 808 nm semiconductor laser in two control modes, the processing thermal history of the printed articles can be obviously eliminated so that the crystallization was more perfect and tended to the intrinsic status, and the bonding strength among extruded filaments can be enhanced through interface fusion so that the printed articles were more compact at the macro level, and the tensile breaking strength of the articles was increased by about 30%.

Example 3

[0075] A double-track asynchronously-controlled 3D printing system was provided, which was substantially the same as that of Example 2, except that the semiconductor laser of Example 3 further comprised a focusing system comprising a converging mirror disposed between a beam collimating mirror and an adjustable attenuator. The 3D printing system of Example 3 employed SLS high-precision printing.

Example 4

[0076] A double-track asynchronously-controlled 3D printing system was provided, which was substantially the same as that of Example 2, except that the semiconductor laser of Example 4 further comprised a focusing system comprising a converging mirror disposed between a beam collimating mirror and an adjustable attenuator. The 3D printing system of Example 4 employed FDM high-precision printing.

[0077] Since line (dot) resolution of less than 0.1 mm is usually required for SLS and FDM high-precision printing, the focus projection distance (generally, centimeter-level or more) from the laser to the printed article is far greater than the image size of the convergent spot, which approximates the Fraunhofer Diffraction. According to rayleigh criterion of diffraction limit (formula 1, wherein x is minimum imaging distance (resolution), f is focal length, λ is laser wavelength, and D is converging mirror diameter), under the condition that the structure size of the 3D printing device and the laser is fixed, the minimum imaging distance x of the laser spot reduces along with the reduction of the wavelength, that is, the resolution of the laser scanning path increases along with the reduction of the wavelength. Therefore, compared with a CO.sub.2 laser adopting far-infrared wavelength, the near-infrared semiconductor laser of the present invention can realize laser scanning with higher precision, and further meet the requirements for preparing SLS-printed and FDM-printed articles with higher precision.

[00001]$\begin{array}{cc}x=\frac{1.22\lambda f}{D}& \left(1\right)\end{array}$

[0078] The examples of the present invention have been described above. However, the present invention is not limited to the above examples. Any modification, equivalent, improvement and the like made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.