A selective laser sintering 3D printed component

Abstract

The present invention belongs to the field of additive manufacturing technology, and specifically relates to a selective laser sintering 3D printing component. It includes a laser generating cavity, a powder forming cavity, a lens switching device, and a lens; the laser generating cavity is located above the powder forming cavity, and there is a gap between the laser generating cavity and the powder forming cavity, which is recorded as a lens gap; a first light-transmitting hole is provided at the bottom of the laser generating cavity, and a second light-transmitting hole is provided at the top of the powder forming cavity. A laser generator is also provided in the laser generating cavity, and the laser emitted by the laser generator passes downward through the first light-transmitting hole and the second light-transmitting hole to reach the powder forming cavity; the lens switching device is installed between the laser generating cavity and the powder forming cavity to switch between different lenses. The present invention adopts a rotary actuator and a multi-lens assembly to realize the switching of the laser flat lens during the SLS printing process, thereby improving the quality and stability of 3D printed products.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and in particular relates to a selective laser sintering 3D printing component. Background Art

[0002] 3D printing technology has developed rapidly in recent years. Selective Laser Sintering (SLS) is one of the most popular 3D printing technologies. It uses thermoplastic powder as a raw material, based on a digital model file, to construct objects by melting the powder through laser heating and solidifying it layer by layer.

[0003] The 3D printing equipment used in SLS technology primarily consists of a powder feeding system, a laser galvanometer system, and a liftable molding chamber system. The liftable molding chamber system is used to form a laser scanning work surface with a constant height and accommodate the finished workpiece. The powder feeding system continuously provides a layer of raw material powder with controllable thickness into the molding chamber. The laser galvanometer system directs laser light to specific areas on the molding chamber surface to melt and shape the raw material powder. A flat lens is fixed between the laser galvanometer system and the molding chamber system to transmit the CO2 laser light while isolating the laser galvanometer system from the molding chamber to ensure a stable temperature field within the molding chamber.

[0004] In practice, we have found that the yield rate of workpieces produced by SLS molding technology is relatively low, especially in terms of mechanical properties, which show low stability. Summary of the Invention

[0005] In response to the above-mentioned problems existing in the prior art, the present invention investigates multiple aspects involved in SLS molding technology, including raw materials, molding processes, and printing equipment. On this basis, it provides a selective laser sintering 3D printing component that can improve the mechanical properties of SLS molded parts as a whole, and in particular, can improve the differences in mechanical properties of SLS molded parts at different thicknesses.

[0006] The selective laser sintering 3D printing component provided by the present invention includes a laser generating cavity, a powder molding cavity, a lens switching device, and a lens; the laser generating cavity is located above the powder molding cavity, and there is a gap between the laser generating cavity and the powder molding cavity, which is recorded as the lens gap; a first light-transmitting hole is provided at the bottom of the laser generating cavity, and a second light-transmitting hole is provided at the top of the powder molding cavity. A laser generator is also provided in the laser generating cavity, and the laser emitted by the laser generator passes downward through the first light-transmitting hole and the second light-transmitting hole to reach the powder molding cavity; the lens switching device is installed between the laser generating cavity and the powder molding cavity, and the lens switching device has a horizontally arranged rotating frame, and a group of detachable lenses are provided in a ring array on the outer edge of the rotating frame; the rotating frame can be rotated intermittently to switch different lenses.

[0007] During the implementation of this invention, we discovered that some of the smoke generated during SLS molding has strong adhesion and can cumulatively adhere to the lens surface. As printing time increases, the attached smoke gradually increases its impact on laser parameters, causing deviations from preset process parameters such as the power, position, and duration of laser exposure to the raw powder. This can lead to variations in the mechanical properties of the product at different thicknesses. To address this issue, the present invention employs a switchable lens, replacing a new lens after each printing period. This minimizes the impact of this adhesive smoke on the product's mechanical properties, resulting in SLS products with excellent mechanical properties.

[0008] Furthermore, the lens switching device also includes a motor, which is rotatably mounted on the output shaft of the motor.

[0009] Furthermore, the rotating frame consists of a set of cantilevers connected in a star shape, with the lens mounted at the end of each cantilever. A sensing unit is fixed to the underside of the cantilever, rotating with the cantilever. A sensor is positioned along the sensing unit's rotation path. The sensing unit and the sensor work together to precisely control the rotating frame's rotation angle, ensuring the lens precisely covers the first light-transmitting aperture.

[0010] Furthermore, the sensing portion is a light shielding sheet, and the sensor is a photoelectric sensor; a light-sensitive gap is provided on the top of the photoelectric sensor, and the photoelectric sensor sends an electrical signal when the light-sensitive gap is blocked.

[0011] Furthermore, the cantilever end has a frame-shaped support platform with a surrounding edge. A lens sleeve is also mounted on the edge of the lens. The sleeve includes a lower sleeve and an upper sleeve that sandwich the lens. The lower sleeve is placed on the support platform. This structure allows the lens sleeve to be easily removed from the support platform or placed on the support platform for lens replacement and cleaning.

[0012] Furthermore, the surrounding edge and the lower mirror cover are both rectangular; a pair of diagonally distributed positioning pins are provided on the base, and a pair of diagonally distributed positioning holes are provided on the lower end surface of the lower mirror cover, and the positions of the positioning pins and the positioning holes correspond to each other.

[0013] Furthermore, a pair of first magnetic blocks are diagonally embedded on the base, and a pair of second magnetic blocks are diagonally embedded on the lower end face of the lower mirror cover. The first magnetic blocks and the second magnetic blocks correspond in position and attract each other to prevent the mirror cover from falling off the base during movement.

[0014] Furthermore, a first lubricating layer is provided on the lower surface of the support platform, and a second lubricating layer is provided on the upper surface of the surrounding edge, thereby reducing the resistance when switching lenses.

[0015] Beneficial Effects: Compared to existing technologies, this invention, based on an in-depth analysis of the unstable mechanical properties of SLS products, provides a selective laser sintering 3D printing assembly. This assembly utilizes a rotary actuator and a multi-lens assembly to facilitate switching between laser flat lenses during SLS printing, offering convenient and simple operation and improving the quality and stability of 3D printed products. The rotary actuator uses an internal photoelectric sensor to control rotation, ensuring precise positioning of the lens assembly. A support with locating pins and magnetic components facilitates lens replacement, prevents lens loss, and ensures accurate positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention.

[0017] Figure 2 It is an explosion diagram of the present invention.

[0018] Figure 3 Schematic diagram of the structure of the lens switching device.

[0019] Figure 4 for Figure 3 A partial enlarged view of .

[0020] Figure 5 and 6 This is a structural diagram of the foundation.

[0021] Figure 7 This is a structural diagram of the lens installation.

[0022] Figure 8 and 9 Schematic diagram of the structure of the lens switching device in Example 2.

[0023] Figure 10 and 11 This is a graph showing the relationship between the tensile strength of the specimen and its thickness.

[0024] In the figure, there are a laser generating cavity 1, a powder forming cavity 2, a lens switching device 3, a lens 4, a lens gap 9, a first light-transmitting hole 11, a second light-transmitting hole 21, a laser generator 8, a rotating frame 31, a motor 32, a sensing part 34, a sensor 35, a base 311, a surrounding edge 312, a lower mirror sleeve 41, an upper mirror sleeve 42, a positioning pin 313, a positioning hole 411, a first magnetic block 314, a second magnetic block 412, a first lubricating layer 315, and a second lubricating layer 316. DETAILED DESCRIPTION

[0025] The present invention is further illustrated by the following examples, which are intended to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the present invention.

[0026] Example 1

[0027] A selective laser sintering 3D printed component, such as Figures 1 to 7 As shown, it includes a laser generating cavity 1, a powder molding cavity 2, a lens switching device 3, and a lens 4; the laser generating cavity 1 is located above the powder molding cavity 2, and there is a gap between the laser generating cavity 1 and the powder molding cavity 2, which is recorded as a lens gap 9; a first light-transmitting hole 11 is provided at the bottom of the laser generating cavity 1, and a second light-transmitting hole 21 is provided at the top of the powder molding cavity 2. A laser generator 8 is also provided in the laser generating cavity 1, and the laser emitted by the laser generator 8 passes downward through the first light-transmitting hole 11 and the second light-transmitting hole 21 to reach the powder molding cavity 2; the lens switching device 3 is installed between the laser generating cavity 1 and the powder molding cavity 2, and the lens switching device 3 has a horizontally arranged rotating frame 31, and a group of detachable lenses 4 are provided in a ring array on the outer edge of the rotating frame 31; the rotating frame 31 can be rotated intermittently to switch different lenses 4.

[0028] In this embodiment, the lens switching device 3 further includes a motor 32 , and the rotating frame 31 is disposed on the output shaft of the motor 32 .

[0029] 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 that rotates with the cantilever is fixed on the lower side of each cantilever, and a sensor 35 is provided on the rotation path of the sensing part 34.

[0030] 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 has a light-sensitive gap, and the photoelectric sensor sends an electrical signal when the light-sensitive gap is blocked.

[0031] In this embodiment, the end of the cantilever has a frame-shaped base 311, and the edge of the base 311 is provided with a surrounding edge 312; a lens sleeve is also mounted on the edge of the lens 4, and the lens sleeve includes a lower lens sleeve 41 and an upper lens sleeve 42 that clamp the lens 4 in the middle; the lower lens sleeve 41 is placed on the base 311.

[0032] In this embodiment, the surrounding edge 312 and the lower mirror cover 41 are both rectangular; a pair of diagonally distributed positioning pins 313 are provided on the base 311, and a pair of diagonally distributed positioning holes 411 are provided on the lower end surface of the lower mirror cover 41, and the positioning pins 313 correspond to the positioning holes 411 in position.

[0033] In this embodiment, a pair of first magnetic blocks 314 are diagonally embedded on the support platform 311, and a pair of second magnetic blocks 412 are diagonally embedded on the lower end surface of the lower mirror cover 41. The first magnetic blocks 314 and the second magnetic blocks 412 are positioned correspondingly.

[0034] In this embodiment, a first lubricating layer 315 is provided on the lower surface of the support platform 311 , and a second lubricating layer 316 is provided on the upper surface of the surrounding edge 312 .

[0035] Example 2

[0036] The difference between the technical solution of this embodiment and embodiment 1 is that a different rotating frame 31 is used, such as Figure 8 and 9 As shown, it consists of three cantilevers connected in a star shape.

[0037] Verification Experiment 1

[0038] The selective laser sintering 3D printing assembly provided in Example 2 was used to print and manufacture TPU material specimens. TPU specimens were printed and manufactured under conditions of switching the lens (the lens was replaced every 90 mm of printing height) and without switching the lens. The prepared specimens were sampled and tested at different thicknesses (test standard: ISO 527).

[0039] Experimental conditions: TPU material, main temperature 110°C, laser power 45W, scan spacing 0.1 mm, scan rate 6000 mm / s, single layer thickness 0.1 mm, packing density 15%. Maintaining the XY position constant, five tensile splines were placed in the Z direction at intervals of 10 mm.

[0040] During the experiment, it can be observed that TPU powder material produces a lot of smoke under the action of laser irradiation. Figure 10 As shown in the figure. Without switching the lens, the tensile strength of the TPU spline gradually decreased with increasing print height. At a height of 250 mm, the tensile strength of the spline decreased by 18.8% compared to 0 mm. With switching the lens, the tensile strength of the TPU spline gradually decreased with increasing print height. At a height of 80 mm, the tensile strength of the spline decreased by 4.4% compared to 0 mm. At a height of 170 mm, the tensile strength of the spline decreased by 4.5% compared to 90 mm. At a height of 250 mm, the tensile strength of the spline decreased by 3.3% compared to 180 mm.

[0041] The results show that by replacing the lens, the tensile strength decrease rate of the TPU sample can be controlled within 5% (indicated by the dotted line in the figure).

[0042] Verification Experiment 2

[0043] The selective laser sintering 3D printing assembly provided in Example 2 was used to print and manufacture test pieces made of PA12 material. The lens was not switched during printing, and the prepared test pieces were sampled and tested at different thicknesses (test standard: ISO 527).

[0044] Experimental conditions: PA12 material, main temperature 170°C, laser power 45W, scan spacing 0.1 mm, scan rate 10,000 mm / s, single layer thickness 0.1 mm, packing density 15%. Maintaining the XY position constant, five tensile splines were placed in the Z direction at intervals of 10 mm.

[0045] During the experiment, it can be observed that PA12 powder material produces almost no smoke under the action of laser irradiation. Figure 11 As shown in the figure, the tensile strength of the PA12 strip remains almost unchanged as the printing height increases, proving that smoke during TPU printing can degrade the performance of printed parts.

[0046] Experiments 1 and 2 show that: (1) During the SLS manufacturing process, an important reason for the instability of the mechanical properties of the product is that the mechanical properties of the same product at different thicknesses have certain differences; (2) The adhesive smoke generated by some SLS raw material powders during the printing process is the main reason for the difference in mechanical properties of the specimens at different thicknesses; (3) The selective laser sintering 3D printing component provided by the present invention can effectively control the difference in mechanical properties caused by the adhesive smoke within a low range, thereby improving the quality of the product.

[0047] The above embodiments are exemplary and intended to illustrate the technical concepts and features of the present invention so that those skilled in the art can understand the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for printing TPU parts using a selective laser sintering 3D printing assembly, characterized in that: A switchable lens (4) is provided, and a new lens (4) is replaced every time printing is performed, thereby controlling the influence of adhesive smoke on the mechanical properties of the product; The selective laser sintering 3D printing component used includes a laser generating cavity (1), a powder forming cavity (2), a lens switching device (3), and a lens (4); the laser generating cavity (1) is located above the powder forming cavity (2), and a gap is provided between the laser generating cavity (1) and the powder forming cavity (2), which is recorded as a lens gap (9); a first light-transmitting hole (11) is provided at the bottom of the laser generating cavity (1), and a second light-transmitting hole (21) is provided at the top of the powder forming cavity (2); a laser generator (8) is also provided in the laser generating cavity (1), and laser light emitted by the laser generator (8) passes downward through the first light-transmitting hole (11) and the second light-transmitting hole (21) to reach the powder forming cavity (2); the lens switching device (3) is installed between the laser generating cavity (1) and the powder forming cavity (2), and the lens switching device (3) has a horizontally arranged rotating frame (31), and a group of detachable lenses (4) are provided in a circular array on the outer edge of the rotating frame (31); the rotating frame (31) can be rotated intermittently to switch different lenses (4); The rotating frame (31) is composed of a group of cantilevers connected in a star shape, and the lens (4) is installed at the end of the cantilever; a sensing part (34) that rotates with the cantilever is fixed on the lower side of the cantilever, and a sensor (35) is provided on the rotation path of the sensing part (34); The end of the cantilever has a frame-shaped support platform (311), and the edge of the support platform (311) is provided with a surrounding edge (312); a lens sleeve is also provided at the edge of the lens (4), and the lens sleeve includes a lower lens sleeve (41) and an upper lens sleeve (42) that clamp the lens (4) in the middle; the lower lens sleeve (41) is placed on the support platform (311); The surrounding edge (312) and the lower mirror cover (41) are both rectangular; a pair of diagonally distributed positioning pins (313) are provided on the support platform (311), and a pair of diagonally distributed positioning holes (411) are provided on the lower end surface of the lower mirror cover (41), and the positioning pins (313) and the positioning holes (411) are positioned correspondingly; A pair of first magnetic blocks (314) are embedded diagonally on the support platform (311), and a pair of second magnetic blocks (412) are embedded diagonally on the lower end surface of the lower mirror sleeve (41), with the first magnetic blocks (314) and the second magnetic blocks (412) corresponding in position. A first lubricating layer (315) is provided on the lower surface of the support platform (311); and a second lubricating layer (316) is provided on the upper surface of the surrounding edge (312).

2. The method according to claim 1, wherein: The lens switching device (3) further comprises a motor (32), and the rotating frame (31) is arranged on an output shaft of the motor (32).

3. The method according to claim 2, wherein: The sensing portion (34) is a light shielding sheet, and the sensor (35) is a photoelectric sensor; a light-sensitive notch is provided on the top of the photoelectric sensor, and the photoelectric sensor sends an electrical signal when the light-sensitive notch is blocked.

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