A sunken 3D printer and 3D printing method

Abstract

The present invention belongs to the technical field of 3D printers, and discloses a sunken 3D printer and a 3D printing method. Among them, the sunken 3D printer includes a main table, a first linear drive mechanism, a second linear drive mechanism, a printing platform and an optical scraper assembly. The main table includes a vertically arranged horizontal table and a vertical table, and a resin tank is provided on the horizontal table; the first linear drive mechanism and the second linear drive mechanism are installed at both ends of the vertical table, the first linear drive mechanism is used to drive the printing platform to move up and down, and the second linear drive mechanism is used to drive the optical scraper assembly to move up and down. The printing precision of the sunken 3D printer is high, and the printed model is solidified and formed above the printing platform. There is no plate falling phenomenon, and larger and heavier 3D models can be printed. The 3D printing method uses the above-mentioned sunken 3D printer, which has high printing precision and high efficiency, and the printing thickness of each layer of the model is accurately controlled, and the printing cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printers, and in particular to a sunken 3D printer and a 3D printing method. Background Art

[0002] The resin tank of a traditional stereolithography 3D printer consists of a resin tank frame, a glass plate, a release film, and a spacer film. The tank contains the photocurable resin, with the optical generator positioned below it and the print platform positioned above it. During 3D printing, the print platform is lowered to the bottom of the tank containing the photocurable resin. The optical generator projects a cross-sectional image of the 3D model through the glass plate, the spacer film, and the release film, before finally irradiating the resin in the gap between the release film and the print platform. This causes a curing reaction between the release film and the print platform, solidifying the resin into the shape of the projected image. The thickness of the cured resin layer is equal to the height of the gap between the print platform and the release film. The print platform then begins to pull upward. Because the print platform is a rigid structure with fine sand grains, the adhesion between the cured resin layer and the print platform is greater than that between the cured resin layer and the release film. As the print platform is pulled upward, the cured resin layer adheres to the print platform and peels away from the release film. When printing the second layer, the print platform is lowered back into the resin tank, leaving a certain gap between it and the release film in the resin tank. The above steps are repeated until the model is printed.

[0003] For traditional light-curing 3D printers, the release film is an elastic transparent film. After repeated use, its elasticity decreases, causing the release film to become loose, affecting printing accuracy. The optical machine is arranged below the resin tank. When small particles are introduced into the resin tank or small pieces of printed models are left, continuing printing will cause the release film or glass plate to break, causing the resin liquid in the tank to flow out onto the optical machine lens, causing permanent damage to the lens. The presence of the glass plate, spacer film, and release film causes the light to undergo six refractions when reaching the resin curing surface, seriously reducing printing accuracy. Moreover, under the influence of the release force, the adhesion between the cured layer resin and the printing platform will become smaller and smaller, and the unprinted model may fall off the printing platform. Summary of the Invention

[0004] The purpose of the present invention is to provide a sunken 3D printer and a 3D printing method to solve the problems of model falling off, low printing accuracy, and the need for regular replacement of printing consumables.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, a sunken 3D printer is provided, comprising:

[0007] A main table top, comprising a vertically arranged horizontal table top and a vertical table top, wherein a resin tank is provided on the horizontal table top;

[0008] a first linear drive mechanism, wherein the first linear drive mechanism is mounted on one end of the vertical table surface close to the horizontal table surface, and a first output end of the first linear drive mechanism is movable upward or downward in a vertical direction;

[0009] a second linear drive mechanism, the second linear drive mechanism being mounted on the other end of the vertical table away from the horizontal table, wherein a second output end of the second linear drive mechanism is movable upward or downward in a vertical direction;

[0010] a printing platform, the printing platform being fixedly connected to the first output end and moving upward or downward along with the first output end;

[0011] An optical scraper assembly is placed above the printing platform and includes:

[0012] an optical-mechanical mechanism, the optical-mechanical mechanism comprising an optical machine and an optical-mechanical mounting seat fixedly connected to each other, the optical-mechanical mounting seat being fixedly connected to the second output end and moving upward or downward with the second output end;

[0013] The scraper mechanism includes a scraper motor, a scraper shaft and a scraper. The scraper motor is fixedly connected to the optical machine mounting seat, one end of the scraper shaft is fixedly connected to the output end of the scraper motor, and the other end of the scraper shaft is fixedly connected to the scraper. A distance measuring sensor is provided on the scraper, and the scraper motor can drive the scraper to perform fan-shaped motion.

[0014] Optionally, the first linear drive mechanism includes:

[0015] a first screw mounting seat, wherein two first screw mounting seats are provided, and the two first screw mounting seats are spaced apart and arranged on the vertical table along the same vertical direction;

[0016] a first driving screw, wherein both ends of the first driving screw are rotatably connected to the two first screw mounting seats;

[0017] a first drive motor, wherein an output end of the first drive motor is fixedly connected to the first drive screw;

[0018] The first driving slider is threadedly connected to the first driving screw. When the first driving motor is started, the first driving slider serves as the first output end of the first linear driving mechanism, and can drive the printing platform to move upward or downward in the vertical direction.

[0019] Optionally, the printing platform includes a platform bracket and a platform support plate, the first linear drive mechanism is installed on the back of the vertical table top, two strip-shaped through holes are opened on the vertical table top, and two platform brackets are provided, and the two platform brackets correspond to the two strip-shaped through holes one by one; one end of the platform bracket is fixedly connected to the platform support plate, and the other end passes through the strip-shaped through hole and is fixedly connected to the first driving slider.

[0020] Optionally, the printing platform further includes a platform bracket connecting block, and both ends of the platform bracket connecting block are fixedly connected to the two platform brackets.

[0021] Optionally, a linear bearing is provided on the platform bracket connecting block, and the scraper shaft passes through the linear bearing.

[0022] Optionally, the second linear drive mechanism includes:

[0023] a second screw mounting seat, wherein two second screw mounting seats are provided, and the two second screw mounting seats are spaced apart and arranged on the vertical table along the same vertical direction;

[0024] a second driving screw, wherein both ends of the second driving screw are rotatably connected to the two second screw mounting seats;

[0025] a second drive motor, wherein an output end of the second drive motor is fixedly connected to the second drive screw;

[0026] The second driving slider is threadedly connected to the second driving screw. When the second driving motor is started, the second driving slider serves as the second output end of the second linear driving mechanism, which can drive the optical mechanism and the scraper mechanism to move upward or downward in the vertical direction.

[0027] Optionally, the second linear drive mechanism further includes a linear guide rail, two linear guide rails are provided, the two linear guide rails are spaced apart and arranged on the vertical table, and the second drive slider is slidably connected to the two linear guide rails.

[0028] Optionally, the ranging sensor is a laser rangefinder.

[0029] In a second aspect, a 3D printing method is provided, using the above-mentioned sunken 3D printer, comprising the following steps:

[0030] Step S1: adding resin liquid into the resin tank, starting the second linear drive mechanism, and moving the scraper to a specified distance Y above the resin liquid surface;

[0031] Step S2: setting the printing layer thickness to a, starting the first linear drive mechanism, causing the printing platform to descend a specified distance X, immerse into the resin liquid, and then ascend a specified distance Xa;

[0032] Step S3: After the printing platform is stabilized, the scraper motor is started, and the scraper rotates to scrape off excess resin liquid on the printing platform that exceeds the printing layer thickness a;

[0033] Step S4: The optical machine is started to solidify the resin liquid with a layer thickness of a remaining on the printing platform, and the resin liquid undergoes a curing reaction to become a solidified resin layer;

[0034] Step S5: After the cured resin layer is cured, the printing platform continues to move down a specified distance X to immerse itself in the resin liquid and then rises a specified distance Xa. The scraper motor is started again to scrape off excess resin liquid exceeding the layer thickness a on the cured resin layer, preparing for printing the next layer.

[0035] Step S6: Repeat steps S4 and S5 until the 3D model is printed.

[0036] Optionally, in step S1, the distance between the scraper and the liquid level of the resin liquid in the resin tank is measured in real time by the distance measuring sensor. When the distance between the scraper and the liquid level of the resin liquid measured by the distance measuring sensor is the specified distance Y, the scraper stops moving.

[0037] Beneficial effects of the present invention:

[0038] The present invention's sunken 3D printer eliminates the need for printing consumables such as release film and spacer film in the resin tank. The printing light path bypasses these films, spacer film, and the resin tank glass, eliminating the effects of refraction on precision and improving model printing accuracy. The printed model solidifies above the print platform, eliminating the risk of plate dropout. Compared to traditional top-up 3D printers, this sunken 3D printer can print larger and heavier 3D models.

[0039] The 3D printing method of the present invention uses the above-mentioned sunken 3D printer, and the printing accuracy and efficiency of the 3D model are high. The printing thickness of each layer of the model is precisely controlled. There is no need to replace printing consumables such as release film and spacer film during the printing process, and the printing manufacturing cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 2 is a front structural diagram of a sunken 3D printer according to an embodiment of the present invention;

[0041] Figure 2 3D printer according to an embodiment of the present invention.

[0042] In the picture:

[0043] 1. Main table; 11. Horizontal table; 111. Resin tank; 12. Vertical table; 121. Strip-shaped through hole;

[0044] 2. First linear drive mechanism; 21. First screw mounting seat; 22. First drive screw; 23. First drive motor; 24. First drive slider;

[0045] 3. Second linear drive mechanism; 31. Second screw mounting base; 32. Second drive screw; 33. Second drive motor; 34. Second drive slider; 35. Linear guide rail;

[0046] 4. Printing platform; 41. Platform bracket; 42. Platform support plate; 43. Platform bracket connecting block; 431. Linear bearing;

[0047] 5. Optical machine scraper assembly; 51. Optical machine mechanism; 511. Optical machine; 512. Optical machine mounting seat; 52. Scraper mechanism; 521. Scraper motor; 522. Scraper shaft; 523. Scraper; 5231. Distance sensor. DETAILED DESCRIPTION

[0048] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar components or components having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but are not to be construed as limiting the present invention.

[0049] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed or detachable connections, mechanical or electrical connections, direct or indirect connections through an intermediate medium, and internal communication between two elements or interaction between two elements. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0050] In the description of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first feature being in direct contact with the second feature, or may include the first feature being in contact with the second feature through another feature between them instead of being in direct contact. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0051] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0052] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0053] like Figure 1-Figure 2 As shown, the present invention provides a sunken 3D printer, comprising a main table 1, a first linear drive mechanism 2, a second linear drive mechanism 3, a printing platform 4 and an optical scraper assembly 5. The main table 1 comprises a horizontal table 11 and a vertical table 12 arranged vertically, the horizontal table 11 and the vertical table 12 being fixedly connected, a resin tank 111 being provided on the horizontal table 11, and the resin tank 111 being used to hold resin liquid. The first linear drive mechanism 2 is mounted on one end of the vertical table 12 close to the horizontal table 11, the first output end of the first linear drive mechanism 2 can move upward or downward in the vertical direction, and the printing platform 4 is fixedly connected to the first output end and moves upward or downward with the first output end. The second linear drive mechanism 3 is mounted on the other end of the vertical table 12 away from the horizontal table 11, the second output end of the second linear drive mechanism 3 can move upward or downward in the vertical direction. The optical scraper assembly 5 is placed above the printing platform 4, and the optical scraper assembly 5 comprises an optical mechanism 51 and a scraper mechanism 52. The optical-mechanical mechanism 51 includes a fixedly connected optical engine 511 and an optical-mechanical mounting base 512. The optical-mechanical mounting base 512 is fixedly connected to the second output terminal and moves upward or downward with the second output terminal. The scraper mechanism 52 includes a scraper motor 521, a scraper shaft 522, and a scraper 523. The scraper motor 521 is fixedly connected to the optical-mechanical mounting base 512. One end of the scraper shaft 522 is fixedly connected to the output end of the scraper motor 521, and the other end of the scraper shaft 522 is fixedly connected to the scraper 523. The scraper 523 is provided with a distance sensor 5231. The scraper motor 521 can drive the scraper 523 to perform fan-shaped motion.

[0054] During printing, resin liquid is injected into the resin tank 111, and the distance sensor 5231 measures the distance from the resin liquid surface. The second linear drive mechanism 3 drives the optical machine scraper assembly 5 to move up or down as a whole, and moves the scraper 523 to a specified distance Y above the resin liquid surface. Then the first linear drive mechanism 2 is started, and the printing platform 4 is first lowered by a specified distance X, so that the printing platform 4 is immersed in the resin liquid, and then the printing platform 4 is raised by a specified distance Xa. At this time, there is a large amount of resin liquid on the printing platform 4, and the scraper motor 521 is started to drive the scraper 523 to rotate in a fan shape, that is, the scraper 523 rotates 180 degrees around the scraper shaft 522, and the plurality of layers on the printing platform 4 exceeding the thickness a are removed. The remaining resin liquid is scraped off to ensure that only resin liquid with a layer thickness of a remains on the printing platform 4; then the optical machine 511 is turned on to project the cross-sectional view of the printed model onto the printing platform 4, so that the resin liquid on the printing platform 4 undergoes a curing reaction. After the printing of this layer is completed, when the second layer is printed, the printing platform 4 is lowered again by a specified distance X to allow the resin liquid to submerge the cured molding surface on the printing platform 4, and then the printing platform 4 is moved up by a specified distance Xa. At this time, the distance between the topmost cured molding surface of the printing platform 4 and the scraper 523 is a, and the scraper 523 rotates to scrape off the excess resin liquid on the cured molding surface that exceeds the layer thickness a, and the above printing operation is repeated until the entire 3D model is printed.

[0055] Optionally, the first linear drive mechanism 2 includes a first screw mounting seat 21, a first drive screw 22, a first drive motor 23, and a first drive slider 24. Two first screw mounting seats 21 are provided, and the two first screw mounting seats 21 are spaced apart along the same vertical direction on the vertical table 12; both ends of the first drive screw 22 are rotatably connected to the two first screw mounting seats 21; the output end of the first drive motor 23 is fixedly connected to the first drive screw 22; and the first drive slider 24 is threadedly connected to the first drive screw 22. When the first drive motor 23 is started, the first drive slider 24 serves as the first output end of the first linear drive mechanism 2, and can drive the printing platform 4 to move upward or downward in the vertical direction.

[0056] Optionally, the second linear drive mechanism 3 includes a second screw mounting base 31, a second drive screw 32, a second drive motor 33, and a second drive slider 34. Two second screw mounting bases 31 are provided, and the two second screw mounting bases 31 are spaced apart and arranged on the vertical table 12 along the same vertical direction. The two ends of the second drive screw 32 are rotatably connected to the two second screw mounting bases 31. The output end of the second drive motor 33 is fixedly connected to the second drive screw 32. The second drive slider 34 is threadedly connected to the second drive screw 32. When the second drive motor 33 is started, the second drive slider 34 serves as the second output end of the second linear drive mechanism 3, which can drive the optical mechanism 51 and the scraper mechanism 52 to move upward or downward in the vertical direction.

[0057] like Figure 1 and Figure 2 As shown, in this embodiment, the first linear drive mechanism 2 and the second linear drive mechanism 3 have the same structure and are both linear modules. The first linear drive mechanism 2 is used to drive the printing platform 4 up and down, and the second linear drive mechanism 3 is used to drive the optical scraper assembly 5 up and down. In this embodiment, the first linear drive mechanism 2 and the second linear drive mechanism 3 are driven by a motor screw, which has good transmission performance, strong load-bearing capacity, and high displacement accuracy. In addition, the first linear drive mechanism 2 and the second linear drive mechanism 3 can also be linear modules of other drive types, or adopt hydraulic drive methods, and are not limited to this embodiment.

[0058] Optionally, the printing platform 4 includes a platform bracket 41 and a platform support plate 42. The first linear drive mechanism 2 is installed on the back of the vertical table 12. Two strip-shaped through holes 121 are opened on the vertical table 12. There are two platform brackets 41, and the two platform brackets 41 correspond to the two strip-shaped through holes 121 one by one. One end of the platform bracket 41 is fixedly connected to the platform support plate 42, and the other end passes through the strip-shaped through hole 121 and is fixedly connected to the first driving slider 24. Figure 1 As shown, the first linear drive mechanism 2 in this embodiment is installed on the back of the vertical table 12, one end of the platform bracket 41 is fixedly connected to the platform support plate 42, and the other end passes through the strip-shaped through hole 121 and is fixedly connected to the first drive slider 24. When the first drive slider 24 moves up and down, it drives the platform bracket 41 and the platform support plate 42 to move up and down synchronously.

[0059] Optionally, the printing platform 4 further includes a platform bracket connecting block 43, and both ends of the platform bracket connecting block 43 are fixedly connected to the two platform brackets 41. Figure 1 As shown, a platform bracket connecting block 43 is fixedly connected between the two platform brackets 41, which enhances the stability between the two platform brackets 41 and ensures the structural strength.

[0060] Optionally, a linear bearing 431 is provided on the platform bracket connection block 43, and the scraper shaft 522 is passed through the linear bearing 431. In this embodiment, the linear bearing 431 is provided on the platform bracket connection block 43. The linear bearing 431 is a commonly used component in the field. The scraper shaft 522 passes through the linear bearing 431 to ensure the coaxiality of the scraper shaft 522 and prevent the scraper shaft 522 from deviating.

[0061] Optionally, the second linear drive mechanism 3 also includes two linear guide rails 35, which are arranged at intervals on the vertical table 12. The second drive slider 34 is slidingly connected to the two linear guide rails 35 to ensure the movement stability of the second drive slider 34.

[0062] Optionally, the distance measuring sensor 5231 in this embodiment is a laser rangefinder, which is a commonly used instrument in this field. In addition, other distance measuring instruments can also be used, and are not limited to this embodiment.

[0063] This embodiment also provides a 3D printing method, using the above-mentioned sunken 3D printer, including the following steps:

[0064] Step S1: adding resin liquid into the resin tank 111, starting the second linear drive mechanism 3, and moving the scraper 523 to a specified distance Y above the resin liquid surface;

[0065] During this step, the distance sensor 5231 measures the distance between the scraper 523 and the resin liquid level in the resin tank 111 in real time. When the distance between the scraper 523 and the resin liquid level measured by the distance sensor 5231 reaches the specified distance Y, the scraper 523 stops moving. It is worth noting that during the printing process, the distance between the scraper 523 and the resin liquid remains at the specified distance Y. As the resin liquid is consumed during printing, the resin liquid level drops, and the scraper 523 also moves downward.

[0066] Step S2: setting the printing layer thickness to a, starting the first linear drive mechanism 2, causing the printing platform 4 to descend a specified distance X, immerse in the resin liquid, and then ascend a specified distance Xa;

[0067] In this step, the printing platform 4 is first lowered by a specified distance X so that the printing platform 4 is immersed in the resin liquid, and then the printing platform 4 is raised by a specified distance Xa. The layer thickness a is the thickness of the resin liquid during each 3D printing, which is set according to the printing requirements.

[0068] Step S3: After the printing platform 4 is stabilized, the scraper motor 521 is started, and the scraper 523 rotates to scrape off excess resin liquid on the printing platform 4 that exceeds the printing layer thickness a;

[0069] In this step, after the printing platform 4 stabilizes, the scraper motor 521 starts to drive the scraper 523 to scrape away excess resin liquid above the printing platform 4 that exceeds the thickness a of the printed layer, ensuring that only the resin liquid layer with a thickness of a remains on the printing platform 4. Specifically, the scraper motor 521 drives the scraper 523 to rotate in a fan-shaped manner. The scraper 523 rotates 180 degrees around the scraper shaft 522 to scrape away excess resin liquid above the thickness a of the printed layer on the printing platform 4, ensuring that only the resin liquid layer with a thickness of a remains on the printing platform 4.

[0070] Step S4: The optical machine 511 is started to solidify the resin liquid with a layer thickness of a remaining on the printing platform 4, and the resin liquid undergoes a solidification reaction to become a solidified resin layer;

[0071] In this step, the optical machine 511 projects the cross-sectional view of the printed model onto the printing platform 4 , causing the resin liquid on the printing platform 4 to undergo a curing reaction.

[0072] Step S5: After the cured resin layer is cured, the printing platform 4 continues to move down a specified distance X to immerse itself in the resin liquid and then rises a specified distance Xa. The scraper motor 521 is started again, and the scraper 523 scrapes off the excess resin liquid exceeding the layer thickness a on the cured resin layer, preparing for printing the next layer.

[0073] In this step, after the resin layer on the printing platform 4 is cured, the printing platform 4 is moved down a specified distance X by the first linear drive mechanism 2, so that the cured resin layer on the printing platform 4 is immersed in the resin liquid. After the immersion is completed, the printing platform 4 is raised again by a specified distance Xa, and the scraper 523 is started to rotate and scrape off the excess resin liquid on the cured resin layer that exceeds the layer thickness a, so that only resin liquid with a layer thickness of a remains on the cured resin layer of the printing platform 4, ready for the next layer of 3D printing with a layer thickness of a.

[0074] Step S6: Repeat steps S4 and S5 until the 3D model is printed.

[0075] In this step, steps S4 and S5 are repeated until the 3D model is printed, and the printing platform 4 rises after the 3D model is printed. The printed 3D model is lifted above the resin liquid level, and then the 3D model is removed.

[0076] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A sunken 3D printer, characterized in that: include: A main table top (1), the main table top (1) comprising a vertically arranged horizontal table top (11) and a vertical table top (12), wherein a resin tank (111) is provided on the horizontal table top (11); a first linear drive mechanism (2), the first linear drive mechanism (2) being mounted on one end of the vertical table (12) close to the horizontal table (11), and a first output end of the first linear drive mechanism (2) being movable upward or downward in a vertical direction; a second linear drive mechanism (3), the second linear drive mechanism (3) being mounted on the other end of the vertical table (12) away from the horizontal table (11), and a second output end of the second linear drive mechanism (3) being movable upward or downward in a vertical direction; A printing platform (4), the printing platform (4) being fixedly connected to the first output end and moving upward or downward along with the first output end; An optical scraper assembly (5), the optical scraper assembly (5) being placed above the printing platform (4), and the optical scraper assembly (5) comprising: An optical-mechanical mechanism (51), the optical-mechanical mechanism (51) comprising an optical machine (511) and an optical-mechanical mounting seat (512) that are fixedly connected, the optical-mechanical mounting seat (512) being fixedly connected to the second output end and moving upward or downward with the second output end; A scraper mechanism (52), the scraper mechanism (52) comprising a scraper motor (521), a scraper shaft (522) and a scraper (523), the scraper motor (521) being fixedly connected to the optical machine mounting seat (512), one end of the scraper shaft (522) being fixedly connected to the output end of the scraper motor (521), and the other end of the scraper shaft (522) being fixedly connected to the scraper (523), a distance sensor (5231) being provided on the scraper (523), and the scraper motor (521) being capable of driving the scraper (523) to perform fan-shaped motion; during the printing process, the distance between the scraper (523) and the resin liquid in the resin tank (111) is always a specified distance Y, and as the resin liquid is continuously consumed during the printing process, the resin liquid level decreases, and the scraper (523) also moves downward accordingly.

2. The sunken 3D printer according to claim 1, characterized in that: The first linear drive mechanism (2) comprises: a first screw mounting seat (21), wherein two first screw mounting seats (21) are provided, and the two first screw mounting seats (21) are spaced apart and arranged on the vertical table (12) along the same vertical direction; a first driving screw (22), wherein both ends of the first driving screw (22) are rotatably connected to the two first screw mounting seats (21); a first drive motor (23), wherein an output end of the first drive motor (23) is fixedly connected to the first drive screw (22); A first driving slider (24) is threadedly connected to the first driving screw (22). When the first driving motor (23) is started, the first driving slider (24) serves as the first output end of the first linear driving mechanism (2) and can drive the printing platform (4) to move upward or downward in a vertical direction.

3. The sunken 3D printer according to claim 2, characterized in that: The printing platform (4) includes a platform bracket (41) and a platform support plate (42), the first linear drive mechanism (2) is installed on the back of the vertical table (12), two strip-shaped through holes (121) are opened on the vertical table (12), and two platform brackets (41) are provided, and the two platform brackets (41) correspond to the two strip-shaped through holes (121) one by one; one end of the platform bracket (41) is fixedly connected to the platform support plate (42), and the other end passes through the strip-shaped through hole (121) and is fixedly connected to the first driving slider (24).

4. The sunken 3D printer according to claim 3, characterized in that: The printing platform (4) further comprises a platform bracket connecting block (43), and both ends of the platform bracket connecting block (43) are fixedly connected to the two platform brackets (41).

5. The sunken 3D printer according to claim 4, characterized in that: A linear bearing (431) is provided on the platform bracket connecting block (43), and the scraper shaft (522) is passed through the linear bearing (431).

6. The sunken 3D printer according to claim 1, characterized in that: The second linear drive mechanism (3) comprises: A second screw mounting seat (31), wherein two second screw mounting seats (31) are provided, and the two second screw mounting seats (31) are spaced apart and arranged on the vertical table (12) along the same vertical direction; a second driving screw (32), wherein both ends of the second driving screw (32) are rotatably connected to the two second screw mounting seats (31); a second drive motor (33), wherein an output end of the second drive motor (33) is fixedly connected to the second drive screw (32); A second driving slider (34) is threadedly connected to the second driving screw (32). When the second driving motor (33) is started, the second driving slider (34) serves as the second output end of the second linear driving mechanism (3) and can drive the optical mechanism (51) and the scraper mechanism (52) to move upward or downward in a vertical direction.

7. The sunken 3D printer according to claim 6, characterized in that: The second linear drive mechanism (3) further includes a linear guide rail (35), two linear guide rails (35) are provided, and the two linear guide rails (35) are spaced apart and arranged on the vertical table (12), and the second drive slider (34) is slidably connected to the two linear guide rails (35).

8. The sunken 3D printer according to any one of claims 1 to 7, characterized in that: The distance measuring sensor (5231) is a laser rangefinder.

9. A 3D printing method, characterized in that: Using the sunken 3D printer according to any one of claims 1 to 8 comprises the following steps: Step S1: adding resin liquid into the resin tank (111), starting the second linear drive mechanism (3), and moving the scraper (523) to a specified distance Y above the surface of the resin liquid; Step S2: setting the thickness of the printing layer to a, starting the first linear drive mechanism (2), causing the printing platform (4) to descend a specified distance X, immerse in the resin liquid, and then ascend a specified distance Xa; Step S3: After the printing platform (4) is stabilized, the scraper motor (521) is started, and the scraper (523) rotates to scrape off excess resin liquid on the printing platform (4) that exceeds the thickness a of the printed layer; Step S4: the optical machine (511) is started to solidify the resin liquid with a layer thickness of a remaining on the printing platform (4), and the resin liquid undergoes a curing reaction to become a solidified resin layer; Step S5: After the solidified resin layer is solidified, the printing platform (4) continues to move down a specified distance X to immerse in the resin liquid and then rises a specified distance Xa. The scraper motor (521) is started again, and the scraper (523) scrapes off the excess resin liquid exceeding the layer thickness a on the solidified resin layer, preparing for printing the next layer. Step S6: Repeat steps S4 and S5 until the 3D model is printed.

10. The 3D printing method according to claim 9, characterized in that: In step S1, the distance between the scraper (523) and the liquid level of the resin liquid in the resin tank (111) is measured in real time by the distance measuring sensor (5231). When the distance between the scraper (523) and the resin liquid measured by the distance measuring sensor (5231) is the specified distance Y, the scraper (523) stops moving.

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