Photo-curing 3D printer and photo-curing 3D printing method for trough sinking type stripping

Abstract

A hollow shaft torque motor of the photocuring 3D printer comprises a rotor, a stator and a hollow shaft, and the stator is fixed to a workbench; the lifting pipe is in threaded engagement with the hollow shaft, and the lifting pipe can only reciprocate in the vertical direction; the sleeve is fixed on the stator, the trough is engaged on the sleeve in a threaded manner, and the guide rod on the hollow shaft is slidably arranged in the guide hole of the trough wall in a penetrating manner; when the rotor rotates, the trough reciprocates between the first working position and the second working position, and the lifting pipe reciprocates between the third working position and the fourth working position. When the material groove is located at the first working position and the lifting pipe is located at the third working position, printing is conducted; and when the material groove is located at the third working position and the lifting pipe is located at the fourth working position, the release film is separated from the product model. The invention further discloses a photocuring 3D printing method. The moving distance and speed of the printing platform are reduced through descending of the material groove, abrasion of the ball screw and the lead screw nut is reduced, and the service life of equipment is prolonged.

Description

Technical Field

[0001] This invention relates to a photopolymer 3D printer with a sink-type peeling material tray and a photopolymer 3D printing method. Background Technology

[0002] In photopolymer 3D printing, the photosensitive material between the printing platform and the release liner solidifies under light irradiation, forming a cured layer that adheres to the printing platform. The platform is then raised to peel the cured layer off the release liner, and the platform is lowered to form the next cured layer. This process is repeated until the desired product model is complete. The strong adhesion between the cured layer and the release liner increases the difficulty of peeling them off, leading to reduced printing efficiency. To improve efficiency, the material tray is typically oscillated or rotated to accelerate the peeling process.

[0003] While the oscillation method can accelerate the peeling of the cured layer from the release film, the photosensitive resin is prone to overflowing from the trough when tilted. To avoid overflowing, the depth of the trough needs to be increased or the liquid volume of the trough needs to be reduced. At the same time, due to the oscillation, air is easily mixed into the photosensitive resin, affecting the printing quality of the product model.

[0004] While rotation can accelerate the separation of the cured layer from the release film, the separation still relies on the lifting of the printing platform. Since the printing platform needs to reciprocate dozens of times per product model, a 10mm high product model with a commonly used cured layer thickness of 0.05mm requires at least 200 prints. This frequent reciprocating motion easily causes wear on the ball screw and screw nut, leading to decreased printing accuracy and reduced lifespan of the printing equipment.

[0005] Therefore, how to accelerate the peeling speed between the cured layer and the release film, improve printing efficiency, reduce the wear of the ball screw, and extend the service life of the printing equipment while ensuring the quality of the product model remains a problem that needs to be solved in the development of pull-up photopolymerization 3D technology. Summary of the Invention

[0006] To at least address some of the aforementioned problems, this application first proposes a bottom-mounted peeling photopolymerization 3D printer, which includes a worktable, on the top plate of which a transmission mechanism and a hollow shaft torque motor are mounted; the transmission mechanism has a printing platform capable of reciprocating in the vertical direction; the hollow shaft torque motor is a servo motor.

[0007] The hollow shaft torque motor includes a mover, a stator, and a hollow shaft arranged coaxially. The stator is rotatably sleeved on the outer periphery of the mover, and the hollow shaft is fixedly lined on the inner wall of the mover. The central axis of the hollow shaft torque motor extends vertically, and the stator is fixed on the worktable. A lifting tube is threaded into the inner side of the hollow shaft. The lifting tube is limited to reciprocating movement only in the vertical direction and cannot rotate relative to the stator. An LCD screen is installed on the top of the lifting tube.

[0008] A sleeve is fixed on the stator, which is coaxially arranged with the hollow shaft. The material trough has an annular groove wall. A release film is installed at the bottom of the groove wall. The groove wall of the material trough is threaded into the inner side of the sleeve. A guide hole extending in the vertical direction is provided in the body of the groove wall. A guide rod is fixedly installed on the hollow shaft and slides through the guide hole.

[0009] The material trough has a first working position and a second working position, and the lifting pipe has a third working position and a fourth working position. When the material trough is in the first working position, the lifting pipe is in the third working position; when the material trough is in the second working position, the lifting pipe is in the fourth working position. When the mover drives the hollow shaft to rotate, the material trough can reciprocate between the first working position and the second working position, and the lifting pipe can reciprocate between the third working position and the fourth working position at the same time.

[0010] Printing can be performed when the material trough is in the first working position and the lifting tube is in the third working position; when the material trough is in the third working position and the lifting tube is in the fourth working position, the release film is separated from the product model on the printing platform.

[0011] In this application, both the material trough and the LCD screen are mounted on a hollow shaft torque motor. When the mover rotates, the material trough and the lifting tube move up and down synchronously, enabling the material trough and the LCD screen to move up and down synchronously as well. When the 3D printer in this application is working, the material trough is first positioned at the first working position, and the lifting tube at the third working position. After printing one cured layer, the mover rotates to lower the material trough to the second working position and the lifting tube to the fourth working position, separating the cured layer from the release film. Then, the material trough is raised to the first working position and the lifting tube to the third working position for printing the next cured layer. Because the material trough rotates simultaneously while moving up and down, the peeling speed between the cured layer and the release film is increased. Since the material trough moves downwards simultaneously during peeling, the lifting height and moving speed of the printing platform are reduced, thereby reducing the rotation speed of the ball screw. Since the printing platform is engaged with the ball screw via a screw nut, wear on the ball screw and screw nut is reduced. Therefore, this application can improve the peeling speed of the cured layer and the release film, while also increasing the service life of the equipment.

[0012] In this application, since part of the moving distance of the printing platform is shared by the movement of the material trough, the descent height of the material trough and the LCD screen can be flexibly adjusted as needed to reasonably distribute the moving distance of the printing platform, as well as the moving distance of the material trough and the LCD screen in the vertical direction. This can minimize the wear of the ball screw and screw nut, thereby improving the service life of the equipment.

[0013] Specifically, a limiting groove extending vertically is provided on the outer circumferential surface of the lifting tube, and a limiting member is fixedly installed on the worktable or stator, which is inserted into the limiting groove. This design can limit the rotation of the lifting tube by the limiting member when the mover rotates, so that the lifting tube can only move back and forth in the vertical direction.

[0014] Furthermore, to avoid the limiting component affecting the printing operation, one end of the limiting component is detachably fixed to the lower side of the stator, and the other end extends into the limiting groove. Installing the limiting component on the lower side of the stator, so that it is located within the inner cavity of the worktable, effectively prevents the limiting component from affecting the printing operation.

[0015] Specifically, in order to make the material trough as close as possible to the LCD screen, the upper surface of the LCD screen should be no lower than the upper end of the lifting tube.

[0016] Furthermore, a translucent glass is installed at the bottom of the material tank, and the release film is laid on this translucent glass. When the material tank is in the first working position and the lifting pipe is in the third working position, the distance between the translucent glass and the LCD screen is 0.2-1mm. This design avoids the release film being directly supported on the LCD screen. When the release film is directly supported on the LCD screen, it will rub against the LCD screen when the material tank rotates. After frequent friction, the light transmittance of the LCD screen will be reduced, thus reducing the photocuring efficiency. By using translucent glass to support the release film and setting the translucent glass and the LCD screen at an interval, the mutual friction between the translucent glass and the LCD screen when the material tank rotates can be effectively avoided, thus preventing the light transmittance of both the translucent glass and the LCD screen from decreasing simultaneously, thereby reducing the photocuring efficiency.

[0017] Furthermore, the printing platform has a vertically extending central axis, and horizontally, the central axis of the printing platform is spaced apart from the central axis of the material trough. Preferably, the distance between the central axis of the printing platform and the central axis of the material trough is 5-15 mm. This design allows relative movement between the bonding areas of the cured layer and the release film when the material trough rotates, facilitating smooth peeling between them. However, when the central axis of the printing platform coincides with the central axis of the material trough, the area of ​​the release film located on the central axis will not move significantly with the cured layer when the trough rotates, and will instead undergo vortex-like twisting around the central axis of the release film, accelerating its failure.

[0018] Furthermore, the pitch of the internal thread of the sleeve is the same as the pitch of the internal thread of the hollow shaft; or the pitch of the internal thread of the sleeve is less than the pitch of the internal thread of the hollow shaft. When the pitch of the internal thread of the sleeve is the same as the pitch of the internal thread of the hollow shaft, the lifting speed of the material trough is the same as the lifting speed of the lifting tube when the hollow shaft rotates, effectively preventing collision between the LCD screen and the material trough. When the pitch of the internal thread of the sleeve is less than the pitch of the internal thread of the hollow shaft, since the initial position of the material trough is in the first working position and the initial position of the lifting tube is in the third working position, and then the material trough and the lifting tube move in the order of descending-rising-descending-rising, the LCD screen on the material trough will not collide with the lifting tube due to the lifting speed of the lifting tube being greater than that of the material trough. However, to avoid collision between the material trough and the LCD screen due to accidental operation causing the lifting tube to rise above the third working position, it is recommended to prioritize the option where the pitch of the internal thread of the sleeve is the same as the pitch of the internal thread of the hollow shaft. To ensure that the trough and the lifting pipe move synchronously downwards or upwards, the internal thread of the sleeve is in the opposite direction to the internal thread of the hollow shaft.

[0019] Secondly, this application also discloses a photopolymer 3D printing method, which uses the dip-type peel-off photopolymer 3D printer described in any of the above claims. The photopolymer 3D printing method includes the following steps:

[0020] (1) Adjust the position of the material tank and the lifting pipe so that the material tank is in the first working position and the lifting pipe is in the third working position; immerse the printing platform into the photosensitive resin in the material tank so that the printing platform and the release film have a gap of one curing layer thickness to complete the printing of the first curing layer.

[0021] (2) Lift the printing platform upwards so that the mover of the hollow shaft torque motor rotates forward and the material trough rotates downwards to reach the second working position. Simultaneously, the lifting tube moves downwards to the fourth working position to complete the peeling of the first curing layer from the release film.

[0022] (3) Reverse the rotor of the hollow shaft torque motor, rotate the material trough upward to the first working position, and move the lifting tube upward to the third working position in sync, lower the printing platform, so that the first curing layer and the release film have a gap of one curing layer thickness, and complete the printing of the second curing layer.

[0023] (4) Repeat steps (2) and (3) to continue printing the curing layer until the product model is printed.

[0024] In this application, during the product model printing process, after each cured layer is printed, the mover rotates, causing the material trough to descend from the first working position to the second working position, and the lifting tube to descend from the second working position to the fourth working position. The material trough rotates simultaneously during this descent, accelerating the separation of the cured layer from the release film. After the cured layer and release film are separated, the material trough rises simultaneously as the printing platform descends. This reduces the reciprocating distance of the lead screw nut on the ball screw, thereby reducing wear between the lead screw nut and the ball screw and improving the service life of the equipment.

[0025] Specifically, the material trough rotates at least 0.2 revolutions. The number of revolutions does not need to exceed one revolution; 0.2-1 revolutions are sufficient, and more preferably 0.2-0.6 revolutions. After the material trough has rotated a certain number of times, the product model and release film have separated. Excessive revolutions do not benefit the separation of the product model and release film. When the material trough rotates, the descent height is controlled between 2-5 mm, and the separation height between the product model and release film is generally controlled between 5-10 mm. This application controls the descent height of the material trough to 2-5 mm, which is 20-50% of the separation height between the product model and release film. This reduces the reciprocating distance of the lead screw nut on the ball screw, thereby reducing the wear between the lead screw nut and the ball screw and improving the service life of the equipment. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of an embodiment of this application.

[0027] Figure 2 yes Figure 1 A view from the center AA direction.

[0028] Figure 3 yes Figure 1 Enlarged view of section B.

[0029] Figure 4 yes Figure 1 Another state diagram shown in the attached figure. Detailed Implementation

[0030] The following section first describes the bottom-feed peel-off photopolymer 3D printer described in this application. Please refer to [link to relevant documentation]. Figures 1-3 The photopolymer 3D printer includes a worktable 10, which includes a vertically extending rectangular cylindrical wall 11, a base plate 12 installed at the bottom of the wall, and a top plate 13 installed at the top of the wall.

[0031] A transmission mechanism is installed on the worktable, comprising a column 15, a lifting motor 21, and a ball screw 22. The column 15 is fixedly mounted on the top plate of the worktable, the lifting motor 21 is mounted on the bottom of the column, the ball screw extends vertically, one end of the lifting arm 16 is engaged with the ball screw via a screw nut, and the other end of the lifting arm extends horizontally away from the ball screw, forming a free end, on which the printing platform 17 is mounted. Driven by the lifting motor, the lifting arm 16 can move up and down along the ball screw, thereby moving the printing platform up and down. The lifting motor 21 is specifically a servo motor, and the specific transmission mechanism can be obtained from existing technology.

[0032] A hollow shaft torque motor 70 is mounted on the top plate 13. The hollow shaft torque motor 70 includes a mover 75 and a stator 71 rotatably fitted around the mover 75. A hollow shaft 76 is fixedly lined inside the mover. An upper end cover 72 and a lower end cover 73 are respectively installed at the upper and lower ends of the stator 71. The upper end cover 72 is bolted to the upper flange 711 at the upper end of the stator 71, and the lower end cover 73 is bolted to the lower flange 712 at the lower end of the stator 71. Both the upper flange 711 and the lower flange 712 are integrally formed on the stator 71. The stator 71, the mover 75, and the hollow shaft 76 are coaxially arranged.

[0033] In this embodiment, an upper connecting flange 761 is provided on the upper part of the outer peripheral surface of the hollow shaft 76, and the upper end cover has an inwardly protruding upper abutting flange 721. The lower surface of the upper abutting flange 721 is a downward-facing stepped surface. The upper abutting flange 721 presses against the upper side of the outer ring of the upper angular contact bearing 771 through its lower surface, and the upper connecting flange 761 presses against the lower side of the inner ring of the upper angular contact bearing, so that the upper end cover is rotatably connected to the hollow shaft 76 through the upper angular contact bearing.

[0034] A lower step portion 762 is provided at the lower part of the outer peripheral surface of the hollow shaft 76. This lower step portion has a downward-facing stepped surface and is formed by a radial inward recess from the outer peripheral surface of the hollow shaft 76. The lower end cover has an inwardly protruding lower abutment flange 731. The upper surface of the lower abutment flange 731 is an upward-facing stepped surface. The lower abutment flange 731 abuts against the lower side of the outer ring of the lower angular contact bearing 772 via its upper surface, and the lower step portion 762 presses against the upper side of the inner ring of the lower angular contact bearing, so that the lower end cover is rotatably connected to the hollow shaft 76 via the lower angular contact bearing. A winding 74 is provided on the inner side of the stator. The structure of the hollow shaft torque motor can be completed using existing mature technology and will not be described in detail.

[0035] In this embodiment, to reduce the impact of the hollow shaft torque motor 70 on the printing operation, a stepped hole 19 is provided on the top plate. The stepped hole 19 is wider at the top and narrower at the bottom, giving it an upward-facing stepped surface 191. A stator flange 713 is provided on the outer peripheral surface of the stator 71. The stator flange is supported on the stepped surface 191, and the fixing bolts 714 connect the stator flange to the top plate 13, thereby mounting the hollow shaft torque motor 70 on the top plate.

[0036] A first internal thread is provided on the inner circumferential surface of the hollow shaft 76, and a first external thread is provided on the outer wall of the lifting tube 41. The lifting tube 41 is engaged with the first internal thread of the hollow shaft 76 via the first external thread, so that the lifting tube 41 is threadedly engaged on the inner side of the hollow shaft 76. The lifting tube 41 is restricted to reciprocating only in the vertical direction and cannot rotate relative to the stator.

[0037] In this embodiment, a vertically extending limiting groove 43 is provided on the outer circumferential surface of the lifting tube. A limiting member 69 is bolted to the lower side of the lower end cover and inserted into the limiting groove 43. The limiting member 69 is specifically a steel plate. One end of the limiting member 69 is detachably fixed to the lower surface of the lower end cover with bolts, and the other end of the limiting member 69 extends into the limiting groove after passing over the mover. When the mover drives the hollow shaft to rotate, due to the limiting effect of the limiting member 69, the lifting tube can only reciprocate in the vertical direction and cannot rotate relative to the hollow shaft.

[0038] To prevent the lifting tube 41 from detaching downward from the hollow shaft 76, a limiting flange 42 is provided at the top of the lifting tube 41. The limiting flange 42 is formed by the outer peripheral surface of the lifting tube protruding radially outward, and the limiting flange 42 can be supported on the top of the hollow shaft, thereby preventing the lifting tube from detaching downward from the hollow shaft 76.

[0039] The LCD screen 18 is mounted on the top of the lifting tube. In this embodiment, the upper surface of the LCD screen is flush with the upper end face of the lifting tube. It can be understood that in other embodiments, the upper surface of the LCD screen can extend upward beyond the upper end face of the lifting tube, but the height by which the upper surface of the LCD screen extends upward beyond the upper end face of the lifting tube should not be too large, generally not exceeding 1mm. To facilitate the installation of the LCD screen 18, a support ring 44 is provided on the inner wall of the lifting tube, and the LCD screen is supported on the support ring.

[0040] The sleeve 36 is fixedly installed on the upper end cover 72. At the lower end of the sleeve, there is a sleeve flange 34 extending radially outward. The sleeve bolt 35 passes through the sleeve flange 34 and is screwed onto the upper end cover 72, so that the sleeve 36 is indirectly fixed to the stator through the upper end cover.

[0041] The sleeve is coaxially arranged with the hollow shaft, and the inner wall of the sleeve has a second internal thread. The material trough 30 has an annular groove wall 31, and a light-transmitting glass 33 is installed at the bottom of the groove wall, with a release film laid on the upper surface of the light-transmitting glass. A second external thread is provided on the outer circumferential surface of the groove wall, and the material trough is screwed onto the second internal thread through the second external thread, so that the groove wall thread engages with the inner side of the sleeve.

[0042] A guide hole 32 extending vertically is provided within the body of the trough wall. A guide rod 37 is fixedly installed on the hollow shaft, and the guide rod slidably passes through the guide hole. In this embodiment, when installing the trough, the trough is first screwed into the sleeve, and after the distance between the trough and the mover reaches a set distance, the guide rod is inserted into the guide hole and screwed into the bolt hole at the top of the hollow shaft. This set distance is determined according to the required descent height of the trough.

[0043] The material trough has a first working position and a second working position, and the lifting pipe has a third working position and a fourth working position. When the material trough is in the first working position, the lifting pipe is in the third working position; when the material trough is in the second working position, the lifting pipe is in the fourth working position. When the mover drives the hollow shaft to rotate, it can make the material trough reciprocate between the first and second working positions, and simultaneously make the lifting pipe reciprocate between the third and fourth working positions.

[0044] Please also refer to Figure 1 and Figure 4 , Figure 1 In the middle, the material trough is in the first working position, while the lifting pipe is in the third working position. Figure 4 In the process, the material tank is in the second working position, and the lifting tube is in the fourth working position. When the material tank is in the first working position and the lifting tube is in the third working position, the printing platform can be immersed in the photosensitive resin in the material tank for printing. When the material tank is in the third working position and the lifting tube is in the fourth working position, the product model on the printing platform is separated from the release film. When the mover drives the hollow shaft to rotate, it can cause the material tank to rotate downward from the first working position to the second working position and simultaneously move the lifting tube downward from the third working position to the fourth working position, or cause the material tank to rotate upward from the second working position to the first working position and simultaneously move the lifting tube upward from the fourth working position to the third working position.

[0045] To prevent friction and wear between the transparent glass and the LCD screen during the rotation of the material tank, in this embodiment, when the material tank is in the first working position and the lifting tube is in the third working position, there is a 0.5mm gap between the transparent glass and the LCD screen. The distance between the transparent glass and the LCD screen should not be too large, preferably 0.2-1mm, and can also be 0.2mm, 0.4mm, 0.8mm or 1mm, or other distances between 0.2-1mm. An ultraviolet light system 14 is installed in the inner cavity of the worktable. The ultraviolet light emitted by this system can illuminate the LCD screen. In this embodiment, the ultraviolet light system adopts existing mature technology, which will not be described in detail.

[0046] To minimize interference from the guide rod during operation, in this embodiment, when the material trough is in the first working position and the lifting pipe is in the third working position, the top of the guide rod is lower than the top of the trough wall. In this embodiment, the guide rod is a cylindrical rod. To facilitate tightening the guide rod, a regular hexagonal tightening hole is provided at the top of the guide rod. An Allen wrench can be inserted into the tightening hole to tighten the guide rod into the threaded hole at the top of the hollow shaft, or to unscrew the guide rod from the threaded hole.

[0047] The printing platform has a second central axis 171 extending vertically. Since the sleeve and hollow shaft are coaxially arranged, and the material trough is screwed onto the sleeve, the material trough and hollow shaft are coaxially arranged, meaning the material trough and hollow shaft torque motor are coaxial. The first central axis 311 of the hollow shaft torque motor 70 is also the central axis of the material trough. Horizontally, there is a distance H between the first and second central axes. In this embodiment, the horizontal distance H between the first and second central axes is 5mm. A horizontal distance H between the first and second central axes is preferably 5-15mm. In other embodiments, the distance H can be selected according to the size of the material trough; the larger the material trough, the larger the horizontal distance H between the first and second central axes. However, there are no special requirements for its specific selection. Figure 2 In the diagram, for clarity, both the second central axis 171 and the first central axis 311 are represented by a small circle, and in... Figure 2 In the diagram, the position of the printing platform within the material trough is indicated by a dashed line.

[0048] The purpose of spacing the first and second center axes is to extend the service life of the release film. When the first and second center axes overlap, the point located on the first center axis is actually stationary when the material tank rotates. Under the influence of the product model, the release film will vortex-like twist around the first center axis, accelerating its failure. By spacing the first and second center axes, the product model and release film can move as a whole when the material tank rotates, avoiding the aforementioned vortex-like twisting. This facilitates the separation of the product model from the release film and ensures the service life of the release film.

[0049] In this embodiment, the pitch of the second internal thread of the sleeve is the same as the pitch of the first internal thread of the hollow shaft, so that when the hollow shaft rotates, the lifting speed of the material trough is the same as the lifting speed of the lifting tube. It can be understood that in another embodiment, the pitch of the second internal thread of the sleeve can be smaller than the pitch of the first internal thread of the hollow shaft. In this case, the lifting speed of the material trough is smaller than the lifting speed of the lifting tube. Since the initial position of the material trough is at the first working position and the lifting tube is at the third working position during operation, and then the material trough and the lifting tube move in a descending-ascending-descending-ascending sequence, the lifting speed of the lifting tube will not be greater than that of the material trough, thus preventing the LCD screen on the material trough from colliding. However, to avoid accidental upward movement of the lifting tube beyond the third working position, causing a collision between the material trough and the LCD screen, it is recommended to preferably use a scheme where the pitch of the second internal thread of the sleeve is the same as the pitch of the first internal thread of the hollow shaft. To ensure that the material trough and the lifting tube move synchronously downward or upward, the helical direction of the second internal thread of the sleeve is opposite to that of the first internal thread of the hollow shaft.

[0050] The following describes the photopolymer 3D printing method in this application. This photopolymer 3D printing method uses the aforementioned dip-feed type peel-off photopolymer 3D printer and includes the following steps:

[0051] (1) Adjust the position of the material tank and the lifting pipe so that the material tank is in the first working position and the lifting pipe is in the third working position; immerse the printing platform into the photosensitive resin in the material tank so that the printing platform and the release film have a gap of one curing layer thickness to complete the printing of the first curing layer.

[0052] (2) Lift the printing platform upwards so that the mover of the hollow shaft torque motor rotates forward and the material trough rotates downwards to reach the second working position. Simultaneously, the lifting tube moves downwards to the fourth working position to complete the peeling of the first curing layer from the release film.

[0053] (3) Reverse the rotor of the hollow shaft torque motor, rotate the material trough upward to the first working position, and move the lifting tube upward to the third working position in sync, lower the printing platform, so that the first curing layer and the release film have a gap of one curing layer thickness, and complete the printing of the second curing layer.

[0054] (4) Repeat steps (2) and (3) to continue printing the curing layer until the product model is printed.

[0055] To maximize printing efficiency, a hollow shaft torque motor is simultaneously activated when the printing platform is raised, causing its mover to rotate forward. When the mover rotates in reverse, the printing platform is lowered simultaneously. In this embodiment, the material trough rotates 0.4 revolutions during the peeling process between the cured layer and the release film.

Claims

1. A light-curing 3D printer with a trough sinking peeling, characterized in that: It includes a workbench, on the top plate of which a transmission mechanism and a hollow shaft torque motor are installed; the transmission mechanism has a printing platform capable of reciprocating in a vertical direction; the hollow shaft torque motor is a servo motor; The hollow shaft torque motor comprises a coaxially arranged mover, a stator and a hollow shaft, wherein the stator is rotatably sleeved on the outer periphery of the mover, the hollow shaft is fixedly lined on the inner wall of the mover, the central axis of the hollow shaft torque motor extends in the vertical direction, and the stator is fixed on a workbench; a lifting tube is threadedly engaged on the inner side of the hollow shaft, the lifting tube is limited to being able to reciprocate only in the vertical direction and cannot be rotated relative to the stator, and a liquid crystal screen is installed on the top of the lifting tube; A sleeve is fixed on the stator, and the sleeve is coaxially arranged with the hollow shaft. The material trough has a groove wall in an annular shape, and a release film is installed at the bottom of the groove wall. The groove wall of the material trough is threadedly engaged with the inner side of the sleeve. A guide hole extending in a vertical direction is arranged in the body of the groove wall. A guide rod is fixedly installed on the hollow shaft, and the guide rod is slidably inserted into the guide hole. The trough has a first working position and a second working position, and the lifting tube has a third working position and a fourth working position. When the trough is located at the first working position, the lifting tube is located at the third working position; when the trough is located at the second working position, the lifting tube is located at the fourth working position; when the mover drives the hollow shaft to rotate, the trough can be reciprocated between the first working position and the second working position, and the lifting tube can be reciprocated between the third working position and the fourth working position at the same time; When the material trough is located at the first working position and the lifting tube is located at the third working position, printing can be performed; When the material trough is located at the third working position and the lifting tube is located at the fourth working position, the release film and the product model on the printing platform are in a separated state.

2. The light-curing 3D printer with trough sinking peeling according to claim 1, characterized in that: A limiting groove extending in the vertical direction is arranged on the outer peripheral surface of the lifting tube, and a limiting member is fixedly installed on the workbench or the stator, and the limiting member is inserted into the limiting groove.

3. The light-curing 3D printer with trough sinking peeling according to claim 2, characterized in that: One end of the limiting member is detachably fixed to the lower side of the stator, and the other end of the limiting member extends into the limiting groove.

4. The light-curing 3D printer with trough sinking peeling according to claim 1, characterized in that: The upper surface of the liquid crystal screen is not lower than the upper end surface of the lifting tube.

5. The light-curing 3D printer with trough sinking peeling according to claim 1, characterized in that: A light-transmitting glass is arranged at the bottom of the material trough, and a release film is laid on the light-transmitting glass; when the material trough is located at the first working position and the lifting tube is located at the third working position, the distance between the light-transmitting glass and the LCD screen is 0.2-1mm.

6. The light-curing 3D printer with trough sinking peeling according to claim 1, characterized in that: The printing platform has a central axis extending in a vertical direction. In a horizontal direction, there is a distance between the central axis of the printing platform and the central axis of the material trough.

7. The light-curing 3D printer with trough sinking peeling according to claim 1, characterized in that: The pitch of the internal thread of the casing is the same as the pitch of the internal thread of the hollow shaft; or the pitch of the internal thread of the casing is smaller than the pitch of the internal thread of the hollow shaft.

8. A light-curing 3D printing method, characterized in that: The method is carried out by using a light-curing 3D printer with a trough-sinking peeling method according to any one of claims 1 to 7, and the light-curing 3D printing method comprises the following steps: (1) Adjusting the positions of the material tank and the lifting tube so that the material tank is located at the first working position and the lifting tube is located at the third working position; immersing the printing platform into the photosensitive resin in the material tank so that there is a gap of the thickness of the solidified layer between the printing platform and the release film, and completing the printing of the first solidified layer; (2) The printing platform is lifted upward, so that the rotor of the hollow shaft torque motor rotates forward, the material trough rotates downward to the second working position, and the lifting tube moves downward to the fourth working position synchronously, completing the peeling of the first solidified layer and the release film; (3) The rotor of the hollow shaft torque motor is reversed, the material trough rotates upward to reach the first working position, and the lifting tube is synchronously moved upward to the third working position, and the printing platform is lowered so that there is a gap of the thickness of the first solidified layer and the release film, and the printing of the second solidified layer is completed; (4) Repeat steps (2) and (3) to continue printing the solidified layer until the product model is printed.

9. The light-curing 3D printing method according to claim 8, characterized in that: The number of revolutions of the trough is ≥ 0.2 revolutions.

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