A pull-up DLP 3D printer and 3D printing method

Abstract

This invention discloses an upward-pull DLP 3D printer and a 3D printing method, belonging to the field of additive manufacturing technology through 3D printing and photopolymerization. It includes a worktable, a Z-axis lifting module, a molding platform, and a resin tank. The worktable includes a release film, a platform, and a curing mechanism. The release film is installed in a square hole in the center of the platform. The 3D printer also includes a main control module, a power transformer, a support bracket, a protective plate, and feet. The curing mechanism includes a light source mounting frame, a DLP projector, and a heat sink. A pressing frame is provided on the resin tank, with its bottom surface connected to the top surface of the release film. An air injection component is provided on the outside of the DLP projector, and an air source component is provided on the outside of the curing mechanism. First connecting ears are fixed on both sides of the resin tank. The bottom of the resin tank is connected to the platform by screws. The top of the light source mounting frame is connected to the platform, and its bottom is connected to the heat sink. The DLP projector and its control circuit are mounted on the top of the heat sink. This invention has the advantage of high release efficiency.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology through 3D printing and photopolymerization, and particularly relates to an up-pull DLP type 3D printer and a 3D printing method. Background Technology

[0002] Pull-up DLP 3D printers, with their high-precision photopolymerization capabilities, have shown broad application prospects in the field of complex model manufacturing. However, the biggest problem with pull-up DLP 3D printers in practical applications is that during the printing platform's ascent, the cured layer and release liner are in a sealed state. This causes the cured layer to struggle against the low-pressure zone between the release liner and the cured layer during peeling, making separation difficult.

[0003] Conventional pull-out DLP 3D printers mostly use a mechanical rigid pulling release method. In this separation method, the release force generated between the cured layer and the release film is relatively large, which can easily lead to defects such as tearing and deformation of the printed model, and also cause significant wear and tear on the release film, affecting the service life of the equipment. Summary of the Invention

[0004] The purpose of this invention is to provide an upward-pull DLP 3D printer and a 3D printing method to solve the problem of insufficient release efficiency in common upward-pull DLP 3D printing equipment.

[0005] The present invention achieves the above objectives through the following technical solution: It includes a worktable, a Z-axis lifting module, a molding platform, and a resin tank. The worktable includes a release film, a platform, and a curing mechanism. The release film is installed in a square hole in the center of the platform. The 3D printer also includes a main control module, a power transformer, a support bracket, a protective plate, and feet. The curing mechanism includes a light source mounting frame, a DLP projector, and a heat sink. A pressing frame is provided on the resin tank, with the bottom surface of the pressing frame attached to the top surface of the release film. An air injection component is provided on the outside of the DLP projector, and an air source component is provided on the outside of the curing mechanism.

[0006] Furthermore, an annular reinforcing layer is provided at the edge of the upper surface of the release film and is pressed together; the Z-axis lifting module, the air source assembly, the DLP projector, and the power transformer are all electrically connected to the main control module.

[0007] Furthermore, the resin tank is fixedly provided with first connecting ears on both sides, the bottom of the resin tank is connected to the platform by screws, the top of the light source mounting frame is connected to the platform, and its bottom is connected to the heat sink. The DLP projector and its control circuit are installed on the top of the heat sink and inside the light source mounting frame.

[0008] Furthermore, the film pressing frame includes an annular frame, which is square, circular, rhomboid, or elliptical in shape. Bending connecting plates are fixedly provided on both sides of the annular frame, and a second connecting ear is fixedly provided at the other end of the bending connecting plate. The inner side of the second connecting ear is connected to the first connecting ear by a connecting screw. The bending connecting plate is in close contact with the wall of the resin tank. The entire film pressing frame is made of high-density polyethylene and is opaque.

[0009] Furthermore, the inner area of ​​the annular frame is not less than the maximum cross-sectional area of ​​the printed model. The shape of the annular frame is selected to match the shape of the printed model. The opaque annular frame has the effect of blocking the light from the DLP projector, preventing the resin outside the model from being incorrectly molded. The bending connecting plate is stuck on the resin tank, reducing the space occupied in the tank.

[0010] Furthermore, the gas ejection assembly includes two square tubes with one end closed. The two square tubes are located on the same axis and are arranged opposite each other on both sides of the DLP projector. An inclined pipe is installed on the top of the closed end of the square tube. The pipe hole of the pipe is connected to the inner tube of the square tube. The other end of the square tube is provided with a pipe joint. The pipe is located outside the light projection range of the DLP projector.

[0011] Furthermore, the arrangement of the pipes outside the light projection range of the DLP projector can avoid blocking the light and causing model loss. The diameter of the square pipe and the number of holes in the pipes are set according to the size of the airflow confluence area to prevent the ejected airflow from falling outside the airflow confluence area and affecting the efficiency of model separation from the release film.

[0012] Furthermore, the internal angle between the plane containing the axis of the tube and the plane containing the perpendicular bisector of the 3D printer is in the range of 15~60°. The top opening of the tube is a beveled cut, and the angle between its cut surface and the horizontal plane is 135~180°. The air hole axes of the two tubes intersect at the bottom center area of ​​the release film. The bottom center area of ​​the release film is defined as the airflow convergence area, and the area of ​​the airflow convergence area does not exceed the area of ​​the annular frame.

[0013] Furthermore, the angle between the pipe and the plane containing the vertical line is set according to the location of the airflow confluence zone, so that the airflow ejected from the pipe falls into the center of the airflow confluence zone. The oblique cut design of the pipe opening can extend the path length of the constrained airflow direction as much as possible, and avoid the rapid dissipation and expansion of the airflow affecting the final landing area. The closer the slope angle is to the horizontal plane, the longer the constraint path for the downward dissipation of the airflow. When the two oblique airflows in different directions converge in the airflow confluence zone, turbulence is generated, which agitates the release film, causing it to vibrate and deform irregularly, resulting in a gap between it and the printed fixing layer, reducing the release force.

[0014] Furthermore, a number of vent holes are provided through the closed end of the square tube, and the airflow direction of the vent holes is directed towards the DLP projector. An annular baffle is installed on the upper part of the outer periphery of the DLP projector, and the height of the annular baffle exceeds the height of the top surface of the square tube. A number of exhaust holes are provided through both sides of the light source mounting frame.

[0015] Furthermore, the airflow ejected from the vent impacts the circular outer shell of the DLP projector and carries away heat, reducing its body temperature and ensuring stable operation. The annular baffle limits the height of the airflow to prevent it from diverging upwards and affecting the direction of the airflow ejected from the exhaust pipe. The airflow sent into the light source mounting frame is finally discharged from the exhaust port.

[0016] Furthermore, one end of the pipe connector is inserted into the square tube and sealed, while the other end is a bamboo-joint structure insertion end. The body of the square tube passes through the light source mounting frame, and a support block is provided at the top of the end of the square tube to support and limit the arrangement of the pipes.

[0017] Furthermore, the air source assembly includes a small air pump, the output end of which is connected to the plug ends of the two pipe fittings via a tee fitting and a plastic tube, and the small air pump is connected to the platform via a bracket and screws.

[0018] Furthermore, the output pressure of the small air pump is set according to the internal volume of the light source mounting frame and the distance between the pipe outlet and the airflow confluence area, so that the airflow still carries a large kinetic energy when it is ejected into the airflow confluence area and is sufficient to form unstable turbulence through impact.

[0019] A 3D printing method for an up-pull DLP type 3D printer:

[0020] This process involves adding raw resin to a resin tank, immersing the Z-axis lifting module in the resin tank, and maintaining a single-layer curing distance between the bottom of the molding platform and the release film as the first layer of printing space. Printing is then performed layer by layer until the entire model is printed.

[0021] After each cured layer is printed, the Z-axis lifting module raises the forming platform to separate the cured layer from the release film. At the same time, a small air pump is started to pump gas into the square tube and eject it from the air holes of the two pipes to the airflow confluence area. The turbulence generated by the collision of the two airflows agitates the release film, creating a gap between the release film and the cured layer, thereby reducing the release force.

[0022] When the molding platform pulls the cured layer upward, the annular frame provides downward pressure to counteract the upward pulling force of the molding platform, thereby pressing the release film and limiting the area of ​​deformation of the release film to within the annular frame until the cured layer separates from the release film.

[0023] Beneficial effects: This invention is reasonably designed and has the following beneficial effects:

[0024] 1. In the present invention, by generating turbulent turbulence to vibrate the release membrane, the rigid tension of conventional mechanical release is transformed into flexible deformation separation, thereby reducing the release force and the risk of model tearing.

[0025] 2. In the present invention, the pressing frame restricts the deformation area of ​​the release film, and the high-precision photocuring of the DLP projector ensures the positional accuracy and surface flatness of each cured layer.

[0026] 3. In the present invention, the air injection component has both heat dissipation and release assistance functions, reducing additional hardware costs. The output pressure of the air pump of the air source component can be adjusted according to printing requirements to adapt to different resin materials and model sizes. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the present invention;

[0028] Figure 2 This is a schematic diagram of the internal structure of the present invention;

[0029] Figure 3 This is a schematic diagram of the workbench structure of the present invention;

[0030] Figure 4 This is a schematic diagram of the resin tank structure of the present invention;

[0031] Figure 5 This is a schematic diagram of the curing mechanism structure of the present invention;

[0032] Figure 6 This is a schematic diagram of the gas ejection assembly structure of the present invention.

[0033] In the diagram: 1-Workbench, 2-Z-axis lifting module, 3-Molding platform, 4-Resin tank, 5-Pressure film frame, 6-Injection assembly, 7-Air source assembly, 8-Airflow confluence area;

[0034] 101-Release film, 102-Tablet, 103-Curing mechanism, 401-First connecting ear, 501-Annular frame, 502-Bent connecting plate, 503-Second connecting ear, 601-Square tube, 602-Pipe arrangement, 603-Pipe connector, 604-Ventilation hole, 701-Small air pump, 702-Plastic tube;

[0035] 1031-Light source mounting frame, 1032-DLP projector, 1033-Heat sink, 1034-Ring baffle, 1035-Exhaust vent. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0038] Example 1

[0039] Combination Figures 1 to 6 The illustrated pull-up DLP 3D printer and 3D printing method include a worktable 1, a Z-axis lifting module 2, a molding platform 3, and a resin tank 4. The worktable 1 includes a release film 101, a platform 102, and a curing mechanism 103. The release film 101 is installed in a square hole in the middle of the platform 102. The 3D printer also includes a main control module, a power transformer, a support bracket, a protective plate, and feet. The curing mechanism 103 includes a light source mounting frame 1031, a DLP projector 1032, and a heat sink 1033. A pressing frame 5 is provided on the resin tank 4, and the bottom surface of the pressing frame 5 is attached to the top surface of the release film 101. An air injection component 6 is provided on the outside of the DLP projector 1032, and an air source component 7 is provided on the outside of the curing mechanism 103.

[0040] Combination Figure 2 , Figure 3 As shown, an annular reinforcing layer is provided at the edge of the upper surface of the release film 101 and is pressed together; the Z-axis lifting module 2, the air source component 7, the DLP projector 1032, and the power transformer are all electrically connected to the main control module.

[0041] Combination Figure 3 , Figure 4 As shown, the resin tank 4 is fixedly provided with first connecting ears 401 on both sides. The bottom of the resin tank 4 is connected to the table plate 102 by screws. The top of the light source mounting frame 1031 is connected to the table plate 102, and its bottom is connected to the heat sink 1033. The DLP projector 1032 and its control circuit are installed on the top of the heat sink 1033 and inside the light source mounting frame 1031.

[0042] Combination Figure 3 , Figure 4 As shown, the film pressing frame 5 includes an annular frame 501, which is square, round, rhomboid, or elliptical in shape. Both sides of the annular frame 501 are fixedly provided with bent connecting plates 502, and the other end of the bent connecting plate 502 is fixedly provided with a second connecting ear 503. The inner side of the second connecting ear 503 is connected to the first connecting ear 401 by connecting screws. The bent connecting plate 502 is close to the wall of the resin tank 4. The film pressing frame 5 is made of high-density polyethylene and is opaque.

[0043] Combination Figure 4 As shown, the inner area of ​​the annular frame 501 is not less than the maximum cross-sectional area of ​​the printed model. The shape of the annular frame 501 is selected to match the shape of the printed model. The opaque annular frame 501 has the effect of blocking the light from the DLP projector 1032, preventing the resin outside the model from being incorrectly molded. The bending connecting plate 502 is stuck on the resin tank 4, reducing the space occupied in the tank.

[0044] Combination Figure 5 , Figure 6 As shown, the air jet assembly 6 includes two square tubes 601 with one end closed. The two square tubes 601 are located on the same axis and are arranged opposite each other on both sides of the DLP projector 1032. An inclined pipe 602 is installed on the top of the closed end of the square tube 601. The pipe hole of the pipe 602 is connected to the inner tube of the square tube 601. The other end of the square tube 601 is provided with a pipe port connector 603. The pipe 602 is located outside the light projection range of the DLP projector 1032.

[0045] Combination Figure 5 , Figure 6 As shown, the pipe 602 is located outside the light projection range of the DLP projector 1032 to avoid blocking the light and causing model loss. The diameter of the square pipe 601 and the number of holes in the pipe 602 are set according to the size of the airflow confluence area 8 to prevent the ejected airflow from falling outside the airflow confluence area 8 and affecting the efficiency of model separation from release film 101.

[0046] Combination Figure 5 , Figure 6 As shown, the internal angle between the plane containing the axis of the tube 602 and the plane containing the perpendicular bisector of the 3D printer is 15~60°. The top opening of the tube 602 is a bevel, and the angle between its cut surface and the horizontal plane is 135~180°. The air hole axes of the two tubes 602 intersect at the bottom center area of ​​the release film 101. The bottom center area of ​​the release film 101 is defined as the airflow convergence area 8. The area of ​​the airflow convergence area 8 does not exceed the area of ​​the annular frame 501.

[0047] Combination Figure 5 , Figure 6As shown, the angle between the pipe 602 and the plane containing the vertical line is set according to the position of the airflow confluence zone 8, so that the airflow ejected from the pipe 602 falls into the center of the airflow confluence zone 8. The oblique cut design of the pipe 602 can extend the path length of the constrained airflow direction as much as possible, and avoid the rapid dissipation and expansion of the airflow affecting the final landing area. The closer the angle of its slope is to the horizontal plane, the longer the constraint path for the downward dissipation of the airflow. When the two oblique airflows in different directions converge in the airflow confluence zone 8, turbulence is generated, which agitates the release film 101, causing it to vibrate and deform irregularly, resulting in a gap between it and the printed fixing layer, reducing the release force.

[0048] Combination Figure 6 As shown, a number of vent holes 604 are provided through the closed end of the square tube 601. The airflow direction of the vent holes 604 is directed towards the DLP projector 1032. An annular baffle 1034 is installed on the upper part of the outer periphery of the DLP projector 1032. The height of the annular baffle 1034 exceeds the height of the top surface of the square tube 601. A number of exhaust holes 1035 are provided through both sides of the light source mounting frame 1031.

[0049] Combination Figure 5 , Figure 6 As shown, the airflow ejected from the vent 604 impacts the circular housing of the DLP projector 1032 and carries away heat, reducing its body temperature and ensuring stable operation. The annular baffle 1034 limits the height of the airflow to prevent it from diverging upwards and affecting the direction of the airflow ejected from the pipe 602. The airflow sent into the light source mounting frame 1031 is finally discharged from the exhaust port 1035.

[0050] Combination Figure 5 , Figure 6 As shown, one end of the pipe connector 603 is inserted into the square tube 601 and sealed together, while the other end is a bamboo-joint structure insertion end. The tube body of the square tube 601 passes through the light source mounting frame 1031, and the top of the end of the square tube 601 is supported and limited by a support block for the pipe 602.

[0051] Combined with the diagram Figure 6 As shown, the air source assembly 7 includes a small air pump 701. The output end of the small air pump 701 is connected to the plug ends of two pipe connectors 603 through a three-way fitting and a plastic pipe 702. The small air pump 701 is connected to the platform 102 through a bracket and screws.

[0052] Combination Figure 5 , Figure 6 As shown, the output pressure of the small air pump 701 is set according to the internal volume of the light source mounting frame 1031 and the distance between the pipe opening of the pipe 602 and the airflow confluence zone 8, so that the airflow still carries a large kinetic energy when it is ejected to the airflow confluence zone 8 and is sufficient to form unstable turbulence through impact.

[0053] A 3D printing method for an up-pull DLP type 3D printer:

[0054] This includes adding raw resin to the resin tank 4, immersing the Z-axis lifting module 2 and the molding platform 3 in the resin tank 4, maintaining a distance of the single-layer curing layer height between the bottom surface of the molding platform 3 and the release film 101 as the printing space for the first layer, and printing layer by layer until the entire model is printed.

[0055] After each cured layer is printed, the Z-axis lifting module 2 lifts the forming platform 3 upward to separate the cured layer from the release film 101. At the same time, the small air pump 701 is started to pump gas into the square tube 601 and eject it from the air holes of the two exhaust pipes 602 to the airflow confluence area 8. The turbulence generated by the collision of the two airflows agitates the release film 101, creating a gap between the release film 101 and the cured layer, thereby reducing the release force.

[0056] When the molding platform 3 pulls the cured layer upward, the annular frame 501 provides downward pressure to counteract the upward pulling force of the molding platform 3, thereby pressing the release film 101 and limiting the area of ​​deformation of the release film 101 within the annular frame 501 until the cured layer separates from the release film 101.

[0057] Example 2

[0058] Structural components:

[0059] 1. Workbench and curing system

[0060] Release film 101: Installed at the holes of the platform 102 as a base for resin curing, with an annular reinforcing layer at its edge to enhance resistance to deformation;

[0061] DLP projector 1032: It is fixed to the heat sink 1033 via the light source mounting frame 1031 and is responsible for projecting ultraviolet light curing resin. The outer air jet component 6 has both heat dissipation and airflow generation functions.

[0062] 2. Release aid system

[0063] Pressing frame 5: A ring frame 501 made of high-density polyethylene is fixed to the resin tank 4 by connecting ears. The bottom surface is attached to the top surface of the release film, which restricts the deformation area of ​​the release film and provides downward pressure.

[0064] Air injection assembly 6 and air source assembly 7: A small air pump 701 supplies air to the square tube 601 and the pipe 602 through a plastic tube 702. The airflow forms turbulence at the bottom center of the release film, which agitates the release film to reduce the release force.

[0065] Example 3

[0066] Working principle:

[0067] (a) Printing preparation stage

[0068] 1. Resin filling and platform positioning

[0069] Liquid photosensitive resin is injected into the resin tank 4, and the Z-axis lifting module 2 drives the molding platform 3 to sink, immersing it in the resin. The bottom surface maintains a single-layer curing layer height (e.g., 0.1mm) with the release film 101, forming the first layer printing space.

[0070] 2. Curing mechanism initialization

[0071] The DLP projector 1032 is activated, projecting an ultraviolet light pattern corresponding to the layer. The release film 101 irradiates the resin in the resin tank 4, causing the resin above the release film to solidify and form the first model layer.

[0072] (II) Layer-by-layer printing and release process

[0073] 1. Curing layer separation drive

[0074] After the first layer is cured, the Z-axis lifting module 2 lifts the forming platform 3 upwards, and the cured layer moves with the platform. At this time, an adhesive force (release force) is generated between the release film 101 and the cured layer.

[0075] 2. Airflow-assisted release mechanism

[0076] Airflow generation: The small air pump 701 of the air source component 7 starts synchronously, and the gas enters the square tube 601 of the air injection component 6 through the three-way fitting and the plastic tube 702, and is ejected from the oblique cut of the exhaust pipe 602.

[0077] Turbulence formation: The airflow from the two pipes 602 is directed at the "airflow convergence zone 8" at the bottom center of the release film at an angle of 15~60°. After the collision, turbulence is generated, which agitates the release film 101 and causes irregular deformation, creating a gap between the cured layer and the release film, which greatly reduces the release force.

[0078] Deformation area restriction: The annular frame 501 of the pressure frame 5 is closely attached to the upper surface of the release film. By applying downward pressure, the deformation area of ​​the release film is restricted within the annular frame to avoid excessive deformation range, which could lead to resin splashing or model displacement.

[0079] 3. Repeated curing and separation

[0080] After the molding platform 3 completes one lifting and separation, the Z-axis module sinks again, so that the bottom surface of the platform and the release film are once again at a single layer height. The DLP projector projects the next layer of pattern, and the "curing lifting airflow release" process is repeated until the model printing is completed.

[0081] (III) Collaborative operation of auxiliary functions

[0082] 1. Heat dissipation and airflow control

[0083] The square tube 601 of the air jet assembly has a vent 604 at its closed end, through which airflow is injected into the housing of the DLP projector 1032 to assist in heat dissipation; the annular baffle 1034 restricts the upward dispersion of airflow to ensure the stability of the airflow direction in the pipe 602.

[0084] 2. Structural stability assurance

[0085] The resin tank 4 is fixed to the table plate 102 with screws. The bent connecting plate 502 of the film pressing frame 5 is close to the wall of the resin tank, which reduces space occupation while enhancing connection strength and preventing the parts from shaking during printing.

[0086] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0087] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A pull-up DLP type 3D printer, comprising a workbench (1), a Z-axis lifting module (2), a forming platform (3) and a resin tank (4), the workbench (1) comprising a release film (101), a table plate (102) and a curing mechanism (103), the release film (101) being installed at a square hole provided in the middle of the table plate (102), the 3D printer further comprising a main control module, a power transformer, a support bracket, a guard plate and a foot, the curing mechanism (103) comprising a light source mounting frame (1031), a DLP projector (1032) and a radiator (1033), characterized in that: The resin tank (4) is provided with a film pressing frame (5), the bottom surface of the film pressing frame (5) is attached to the top surface of the release film (101), the outer side of the DLP projector (1032) is provided with a gas injection assembly (6), and the outer side of the curing mechanism (103) is provided with a gas source assembly (7); The gas injection assembly (6) includes two square tubes (601) with one end closed, the two square tubes (601) are located on the same axis and are oppositely arranged on the two sides of the DLP projector (1032), the top of the closed end of the square tube (601) is provided with an inclined exhaust pipe (602), the pipe hole of the exhaust pipe (602) is connected with the inner tube of the square tube (601), and the other end of the square tube (601) is provided with a pipe joint (603); the exhaust pipe (602) is located outside the light projection range of the DLP projector (1032). The angle between the plane where the axis of the exhaust pipe (602) is located and the plane where the perpendicular line of the 3D printer is located is in the range of 15-60°, the top opening of the exhaust pipe (602) is an inclined cut, the angle between the cutting surface and the horizontal plane is 135-180°, and the gas hole axes of the two exhaust pipes (602) intersect at the bottom center area of the release film (101), which is defined as the airflow intersection area (8).

2. The pull-up DLP type 3D printer according to claim 1, characterized in that: The resin tank (4) is provided with a film pressing frame (5), the bottom surface of the film pressing frame (5) is attached to the top surface of the release film (101), the outer side of the DLP projector (1032) is provided with a gas injection assembly (6), and the outer side of the curing mechanism (103) is provided with a gas source assembly (7); 3. The pull-up DLP type 3D printer according to claim 2, characterized in that: The film pressing frame (5) includes an annular frame (501), the shape of the annular frame (501) is one of square, circle, diamond, and oval, the two sides of the annular frame (501) are fixedly provided with a bent connecting plate (502), the other end of the bent connecting plate (502) is fixedly provided with a second connecting lug (503), the inner side of the second connecting lug (503) is connected with the first connecting lug (401) through a connecting screw, the bent connecting plate (502) is closely attached to the wall surface of the resin tank (4), the film pressing frame (5) is made of high-density polyethylene and is light-tight, and the area of the airflow intersection area (8) is not greater than the area of the annular frame (501).

4. The pull-up DLP type 3D printer according to claim 3, characterized in that: A plurality of air holes (604) are provided on the closed end of the square tube (601), the output airflow direction of the air holes (604) points to the DLP projector (1032), an annular baffle (1034) is mounted on the upper part of the outer periphery of the DLP projector (1032), the height of the annular baffle (1034) exceeds the height of the top surface of the square tube (601), and a plurality of air exhaust holes (1035) are provided on the two sides of the light source mounting frame (1031).

5. The pull-up DLP type 3D printer according to claim 4, characterized in that: The pipe joint (603) is inserted into the square tube (601) at one end and is sealed, and the other end is a joint end with a bamboo joint structure. The tube body of the square tube (601) penetrates the light source mounting frame (1031), and the end top of the square tube (601) supports and limits the pipe (602) by arranging a support block.

6. The pull-up DLP type 3D printer according to claim 5, characterized in that: The air source assembly (7) comprises a small air pump (701), the output end of the small air pump (701) is connected with the joint end of two pipe joints (603) through a three-way pipe and a plastic pipe (702), and the small air pump (701) is connected with the table plate (102) through a support and a screw.

7. The 3D printing method of the pull-up type DLP 3D printer according to claim 6, comprising adding raw resin in the resin tank (4), sinking the Z-axis lifting module (2) to immerse the forming platform (3) in the resin tank (4), keeping the bottom surface of the forming platform (3) away from the release film (101) by a single layer of solidified layer height as a printing space of the first layer, and printing layer by layer until the whole model is printed; characterized in that After printing each solidified layer, the Z-axis lifting module (2) lifts the forming platform (3) upward to separate the solidified layer from the release film (101), and at the same time, the small air pump (701) is started to pump gas into the square tube (601) and emit from the air holes of the two pipes (602) to the airflow intersection area (8), the turbulence generated by the collision of the two airflows drives the release film (101), so that a gap is generated between the release film (101) and the solidified layer, thereby reducing the release force; When the forming platform (3) pulls up the solidified layer, the annular frame (501) provides a downward pressure to resist the upward pulling force of the forming platform (3) for pressing the release film (101), so that the area of the deformed region of the release film (101) is limited in the annular frame (501), until the solidified layer is separated from the release film (101).

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