阅读说明：本技术 一种选择性激光烧结3d打印组件 (Selective laser sintering 3D printing assembly ) 是由 杜湘云 付政 胡焕波 芮正国 黄建昌 于 2021-09-13 设计创作，主要内容包括：本发明属于增材制造技术领域,具体涉及一种选择性激光烧结3D打印组件。它包括激光发生腔体、粉末成型腔体、透镜切换装置、透镜；激光发生腔体位于粉末成型腔体上方,激光发生腔体与粉末成型腔体中间具有间隙,记为透镜间隙；在激光发生腔体底部具有第一透光孔,在粉末成型腔体顶部具有第二透光孔,激光发生腔体内还设有激光发生器,激光发生器发出的激光向下穿过第一透光孔和第二透光孔到达粉末成型腔体内；透镜切换装置安装在激光发生腔体和粉末成型腔体之间以切换不同的透镜。本发明采用旋转执行机构和多镜片组件,实现SLS打印过程中激光平透镜的切换,提升3D打印产品的质量以及稳定性。(The invention belongs to the technical field of additive manufacturing, and particularly relates to a selective laser sintering 3D printing assembly. The laser powder molding device comprises a laser generation cavity, a powder molding cavity, a lens switching device and a lens; the laser generating cavity is positioned above the powder forming cavity, and a gap is formed between the laser generating cavity and the powder forming cavity and is marked as a lens gap; the bottom of the laser generation cavity is provided with a first light hole, the top of the powder forming cavity is provided with a second light hole, a laser generator is also arranged in the laser generation cavity, and laser emitted by the laser generator downwards penetrates through the first light hole and the second light hole to reach the inside of the powder forming cavity; the lens switching device is arranged between the laser generation cavity and the powder molding cavity to switch different lenses. According to the invention, the rotary actuator and the multi-lens assembly are adopted, so that the switching of the laser flat lens in the SLS printing process is realized, and the quality and the stability of a 3D printed product are improved.)

1. The utility model provides a selectivity laser sintering 3D printing module which characterized in that: comprises a laser generating cavity (1), a powder forming cavity (2), a lens switching device (3) and a lens (4); the laser generation cavity (1) is positioned above the powder forming cavity (2), and a gap is formed between the laser generation cavity (1) and the powder forming cavity (2) and is marked as a lens gap (9); the bottom of the laser generation cavity (1) is provided with a first light hole (11), the top of the powder forming cavity (2) is provided with a second light hole (21), a laser generator (8) is further arranged in the laser generation cavity (1), and laser emitted by the laser generator (8) downwards penetrates through the first light hole (11) and the second light hole (21) to reach the powder forming cavity (2); the lens switching device (3) is arranged between the laser generation cavity (1) and the powder forming cavity (2), the lens switching device (3) is provided with a rotary frame (31) which is horizontally arranged, and a group of detachable lenses (4) are arranged on the outer edge of the rotary frame (31) in an annular array mode; the rotary frame (31) can be intermittently rotated to switch different lenses (4).

2. The selective laser sintering 3D printing assembly of claim 1, wherein: the lens switching device (3) further comprises a motor (32), and the rotary frame (31) is arranged on an output shaft of the motor (32).

3. The selective laser sintering 3D printing assembly of claim 1, wherein: the rotary frame (31) consists of a group of cantilevers connected in a star shape, and the lens (4) is arranged at the tail end of each cantilever; a sensing part (34) rotating with the cantilever is fixed on the lower side of the cantilever, and a sensor (35) is arranged on the rotating path of the sensing part (34).

4. The selective laser sintering 3D printing assembly of claim 3, wherein: the sensing part (34) is a shading sheet, and the sensor (35) is a photoelectric sensor; the top of the photoelectric sensor is provided with a light sensing gap, and the photoelectric sensor sends out an electric signal when the light sensing gap is shielded.

5. The selective laser sintering 3D printing assembly of claim 3, wherein: the tail end of the cantilever is provided with a frame-shaped bearing platform (311), and the edge of the bearing platform (311) is provided with a surrounding edge (312); the edge of the lens (4) is also sleeved with a lens sleeve, and the lens sleeve comprises a lower lens sleeve (41) and an upper lens sleeve (42) which clamp the lens (4) in the middle; the lower lens sleeve (41) is placed on the bearing platform (311).

6. The selective laser sintering 3D printing assembly of claim 5, wherein: the surrounding edge (312) and the lower mirror sleeve (41) are both rectangular; a pair of positioning pins (313) which are distributed diagonally are arranged on the bearing platform (311), a pair of positioning holes (411) which are distributed diagonally are arranged on the lower end surface of the lower mirror sleeve (41), and the positioning pins (313) correspond to the positioning holes (411) in position.

7. The selective laser sintering 3D printing assembly of claim 6, wherein: a pair of first magnetic blocks (314) are embedded on the bearing platform (311) in a diagonally distributed manner, a pair of second magnetic blocks (412) are embedded on the lower end surface of the lower mirror sleeve (41) in a diagonally distributed manner, and the first magnetic blocks (314) correspond to the second magnetic blocks (412) in position.

8. The selective laser sintering 3D printing assembly of claim 5, wherein: a first lubricating layer (315) is arranged on the lower surface of the bearing platform (311); the upper surface of the surrounding edge (312) is provided with a second lubricating layer (316).

Technical Field

The invention belongs to the technical field of additive manufacturing, and particularly relates to a selective laser sintering 3D printing assembly.

Background

In recent years, 3D printing technology has been rapidly developed. Among them, the Selective Laser Sintering (SLS) technology is based on a digital model file, uses thermoplastic powder as a raw material, and builds an object by melting the powder through laser heating and solidifying, stacking and accumulating layer by layer, which is one of the most popular 3D printing technologies at present.

The 3D printing equipment adopted by the SLS technology mainly comprises functional units such as a powder feeding system, a laser galvanometer system, a liftable molding cavity system and the like. The liftable forming cavity system is used for forming a laser scanning working face with constant height and accommodating a formed workpiece, the powder supply system is used for continuously providing a raw material powder layer with controllable thickness in the forming cavity, the laser galvanometer system is used for sending laser to a specific area on the surface of the forming cavity to melt and form the raw material powder, and a flat lens is fixedly arranged between the laser galvanometer system and the forming cavity system and used for transmitting CO₂And laser is isolated from the laser galvanometer system and the molding cavity simultaneously so as to ensure the stability of the temperature field in the molding cavity.

In practice, the workpieces prepared by the SLS forming technology have low yield and particularly show low stability in terms of mechanical properties.

Disclosure of Invention

In order to solve the problems in the prior art, the invention inspects a plurality of aspects of raw materials, forming processes, printing equipment and the like related to the SLS forming technology, and provides the selective laser sintering 3D printing component on the basis, so that the mechanical property of the SLS formed part can be integrally improved, and the difference of the mechanical properties of the SLS formed part in different thicknesses can be particularly improved.

The invention provides a selective laser sintering 3D printing assembly which comprises a laser generating cavity, a powder forming cavity, a lens switching device and a lens, wherein the laser generating cavity is provided with a laser source; the laser generating cavity is positioned above the powder forming cavity, and a gap is formed between the laser generating cavity and the powder forming cavity and is marked as a lens gap; the bottom of the laser generation cavity is provided with a first light hole, the top of the powder forming cavity is provided with a second light hole, a laser generator is also arranged in the laser generation cavity, and laser emitted by the laser generator downwards penetrates through the first light hole and the second light hole to reach the inside of the powder forming cavity; the lens switching device is arranged between the laser generation cavity and the powder forming cavity and is provided with a horizontally arranged rotary frame, and a group of detachable lenses are arranged on the outer edge of the rotary frame in an annular array manner; the turret may be rotated intermittently to switch different lenses.

In the implementation process of the invention, we find that part of smoke generated during SLS forming has strong adhesive force and can be cumulatively attached to the surface of a lens, and the influence of the attached smoke on laser parameters is gradually increased along with the extension of printing time, so that technological parameters such as power, position and time of actually receiving laser by raw material powder deviate from preset values, and the mechanical properties of products on different thicknesses are changed. In contrast, the switchable lens is arranged, and the lens is replaced every time the printer prints for a period of time, so that the influence of the adhesive smoke on the mechanical property of the product is controlled in a lower range, and the SLS product with excellent mechanical property is obtained.

Further, the lens switching device also comprises a motor which is arranged on an output shaft of the motor in a rotating mode.

Furthermore, the rotary frame consists of a group of cantilevers connected in a star shape, and the lens is arranged at the tail end of each cantilever; the lower side of the cantilever is fixed with a sensing part rotating along with the cantilever, and a sensor is arranged on a rotating path of the sensing part. Through the cooperation of response portion and inductor, can carry out accurate control to revolving rack pivoted angle, make lens cover first light trap just.

Furthermore, the sensing part is a shading sheet, and the sensor is a photoelectric sensor; the top of the photoelectric sensor is provided with a light sensing gap, and the photoelectric sensor sends out an electric signal when the light sensing gap is shielded.

Furthermore, the tail end of the cantilever is provided with a frame-shaped bearing platform, and the edge of the bearing platform is provided with a surrounding edge; the edge of the lens is also sleeved with a lens sleeve, and the lens sleeve comprises a lower lens sleeve and an upper lens sleeve which clamp the lens in the middle; the lower mirror sleeve is placed on the bearing platform. The lens sleeve can be conveniently taken down from the bearing platform or placed on the bearing platform through the structure, so that the lens can be conveniently replaced and cleaned.

Furthermore, the surrounding edge and the lower mirror sleeve are rectangular; the bearing platform is provided with a pair of positioning pins which are distributed diagonally, the lower end surface of the lower mirror sleeve is provided with a pair of positioning holes which are distributed diagonally, and the positioning pins correspond to the positioning holes in position.

Furthermore, a pair of first magnetic blocks is embedded on the bearing platform in a diagonally distributed manner, a pair of second magnetic blocks is embedded at the lower end face of the lower mirror sleeve in a diagonally distributed manner, and the first magnetic blocks and the second magnetic blocks are corresponding in position and mutually attracted, so that the mirror sleeve is prevented from falling off from the bearing platform during movement.

Further, the lower surface of the bearing platform is provided with a first lubricating layer, and the upper surface of the surrounding edge is provided with a second lubricating layer, so that the resistance in switching the lenses is reduced.

Has the advantages that: compared with the prior art, the selective laser sintering 3D printing assembly is provided on the basis of deep combing and analyzing the problem of unstable mechanical property of an SLS product, the switching of the laser flat lens in the SLS printing process is realized by adopting the rotary executing mechanism and the multi-lens assembly, the operation is convenient and simple, and the quality and the stability of the 3D printing product are improved. The rotation actuating mechanism controls rotation through an internal photoelectric sensing device, and accurate positioning of the lens assembly is guaranteed; the bearing platform with the positioning pin and the magnetic part not only facilitates the replacement of the lens, but also is not easy to fall off, and can also accurately position.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Fig. 2 is an exploded view of the present invention.

Fig. 3 is a schematic structural diagram of the lens switching device.

Fig. 4 is a partially enlarged view of fig. 3.

Fig. 5 and 6 are schematic views of the structure at the cap.

Fig. 7 is a schematic view of a lens mounting structure.

Fig. 8 and 9 are schematic structural views of a lens switching device in embodiment 2.

Fig. 10 and 11 are graphs showing the tensile strength of the test pieces as a function of thickness.

In the figure, the laser generation cavity 1, the powder molding cavity 2, the lens switching device 3, the lens 4, the lens gap 9, the first light transmission hole 11, the second light transmission hole 21, the laser generator 8, the rotating frame 31, the motor 32, the sensing part 34, the sensor 35, the bearing platform 311, the surrounding edge 312, the lower mirror sleeve 41, the upper mirror sleeve 42, the positioning pin 313, the positioning hole 411, the first magnetic block 314, the second magnetic block 412, the first lubricating layer 315 and the second lubricating layer 316.

Detailed Description

The invention is further illustrated by the following examples, which are intended to illustrate the technical solutions of the invention more clearly and are not to be construed as a limitation.

Example 1

A selective laser sintering 3D printing assembly, as shown in fig. 1 to 7, includes a laser generating cavity 1, a powder forming cavity 2, a lens switching device 3, and a lens 4; the laser generation cavity 1 is positioned above the powder forming cavity 2, and a gap is formed between the laser generation cavity 1 and the powder forming cavity 2 and is marked as a lens gap 9; the bottom of the laser generation cavity 1 is provided with a first light hole 11, the top of the powder forming cavity 2 is provided with a second light hole 21, a laser generator 8 is further arranged in the laser generation cavity 1, and laser emitted by the laser generator 8 downwards penetrates through the first light hole 11 and the second light hole 21 to reach the inside of the powder forming cavity 2; the lens switching device 3 is arranged between the laser generation cavity 1 and the powder forming cavity 2, the lens switching device 3 is provided with a rotary frame 31 which is horizontally arranged, and a group of detachable lenses 4 are arranged on the outer edge of the rotary frame 31 in an annular array; the turret 31 may be rotated intermittently to switch different lenses 4.

In this embodiment, the lens switching device 3 further includes a motor 32, and the rotating frame 31 is disposed on an output shaft of the motor 32.

In this embodiment, the rotating frame 31 is composed of four cantilevers connected in a star shape, and the lens 4 is installed at the end of the cantilever; a sensing part 34 rotating with the cantilever is fixed to the lower side of each cantilever, and a sensor 35 is provided on the rotation path of the sensing part 34.

In this embodiment, the sensing portion 34 is a light shielding sheet, and the sensor 35 is a photoelectric sensor; the top of the photoelectric sensor is provided with a light sensing gap, and the photoelectric sensor sends out an electric signal when the light sensing gap is shielded.

In this embodiment, the end of the cantilever has a frame-shaped bearing platform 311, and the edge of the bearing platform 311 is provided with a surrounding edge 312; the edge of the lens 4 is also sleeved with a lens sleeve which comprises a lower lens sleeve 41 and an upper lens sleeve 42 which clamp the lens 4 in the middle; the lower lens housing 41 is placed on the stage 311.

In this embodiment, the surrounding edge 312 and the lower lens sleeve 41 are both rectangular; a pair of positioning pins 313 are provided on the platform 311 in a diagonal arrangement, a pair of positioning holes 411 are provided on the lower end surface of the lower mirror sleeve 41 in a diagonal arrangement, and the positioning pins 313 correspond to the positioning holes 411 in position.

In this embodiment, a pair of first magnetic blocks 314 are embedded on the supporting platform 311 in a diagonally distributed manner, a pair of second magnetic blocks 412 are embedded on the lower end of the lower mirror sleeve 41 in a diagonally distributed manner, and the first magnetic blocks 314 correspond to the second magnetic blocks 412 in position.

In this embodiment, the first lubricating layer 315 is disposed on the lower surface of the platform 311; the upper surface of the skirt 312 is provided with a second lubricant layer 316.

Example 2

The solution of the present embodiment differs from embodiment 1 in that a different swing frame 31 is used, which consists of three star-connected arms, as shown in fig. 8 and 9.

Verification experiment 1

The selective laser sintering 3D printing assembly provided in example 2 was used to print test pieces of TPU material, the TPU test pieces were printed and manufactured with and without switching lenses (the lenses were changed every 90 mm height printed), and the test pieces obtained were sampled and tested at different thicknesses (test standard: ISO 527).

The experimental conditions are as follows: the TPU material has a main temperature of 110 ℃, laser power of 45W, scanning interval of 0.1 mm, scanning speed of 6000 mm/s, single-layer printing layer thickness of 0.1 mm and bale arranging density of 15%. 5 tensile bars were placed at intervals of 10 mm in the Z direction while maintaining the XY position.

In the experimental process, a great amount of smoke generated by the TPU powder material under the action of the irradiation laser can be observed. The results of the experiment are shown in FIG. 10. Without switching lenses, the tensile strength of the TPU splines decreased gradually with increasing print height, with a 250 mm height spline having a 18.8% decrease in tensile strength over 0 mm. Under the condition of switching lenses, the tensile strength of the TPU splines gradually decreases with the increase of the printing height, and the tensile strength of the splines decreases by 4.4% when the height is 80 mm compared with that of the splines with the height of 0 mm. The tensile strength of the specimen at a height of 170 mm was 4.5% lower than that at 90 mm, and the tensile strength of the specimen at a height of 170 mm was 4.5% lower than that at 90 mm. The tensile strength of the specimen at a height of 250 mm decreases by 3.3% as compared with that at 180 mm.

The results show that the reduction rate of tensile strength of the TPU sample can be controlled within 5% (shown by a dotted line) by replacing the lens.

Verification experiment 2

Test pieces of the PA12 material were produced by printing using the selective laser sintering 3D printing module provided in example 2, without switching the lenses during printing, and the test pieces produced were sampled and tested at different thicknesses (test standard: ISO 527).

The experimental conditions are as follows: PA12 material, main temperature 170 ℃, laser power 45W, scanning interval 0.1 mm, scanning speed 10000 mm/s, single-layer printing layer thickness 0.1 mm, and bale arranging density 15%. 5 tensile bars were placed at intervals of 10 mm in the Z direction while maintaining the XY position.

In the experimental process, it can be observed that the PA12 powder material hardly generates smoke under the action of the irradiated laser. The results of the experiment are shown in FIG. 11. The tensile strength of the PA12 spline is nearly constant with increasing print height, demonstrating that smoke can degrade print performance during TPU printing.

Experiments 1 and 2 show that: (1) in the SLS manufacturing process, an important reason for unstable mechanical properties of products is that the mechanical properties of the same product have certain difference in different thicknesses; (2) adhesive smoke generated by part of SLS raw material powder in the printing process is a main reason for causing the difference of mechanical properties of the test piece on different thicknesses; (3) the selective laser sintering 3D printing assembly provided by the invention can effectively control the difference of mechanical properties caused by adhesive smoke in a lower range, thereby improving the quality of products.

The above embodiments are exemplary only, and are intended to illustrate the technical concept and features of the present invention so that those skilled in the art can understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.