A top-pull light-curing 3D printer and light-curing 3D printing method

Abstract

The present application discloses a top-pull photocuring 3D printer, wherein the outer ring of the slewing bearing is fixed on the workbench, the lifting tube thread is engaged with the inner side of the inner ring, and the lifting tube can only reciprocate in the vertical direction; the sleeve is fixed on the outer ring, the material trough thread is engaged with the outer ring, and the guide rod on the inner ring is slidably penetrated in the guide hole of the material trough; when the inner ring rotates, the material trough reciprocates between the first and second working positions, and the lifting tube reciprocates between the third and fourth working positions; 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 second 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. The present application also discloses a photocuring 3D printing method. The present application utilizes the descent of the material trough to reduce the up and down moving distance and speed of the printing platform, reduce the wear of the ball screw and the screw nut, and improve the service life of the equipment.

Description

Technical Field

[0001] The invention relates to a top-pull light-curing 3D printer and a light-curing 3D printing method. Background Art

[0002] When using the pull-up light-curing 3D printing technology for printing, the light source system irradiates the photosensitive material in the gap between the printing platform and the release film, causing the photosensitive material to solidify and adhere to the printing platform to form a solidified layer. After the production of a solidified layer is completed, the printing platform is lifted, and a gap is formed again between the solidified layer and the release film, and the next solidified layer is formed. The printing platform is lifted again, and a new solidified layer is continuously formed until the required product model is completed. Due to the adhesion between the solidified layer and the release film, it will increase the difficulty of lifting the printing platform, resulting in a decrease in printing efficiency. In order to improve printing efficiency, the material trough is usually swung or rotated to speed up the separation of the solidified layer and the release film.

[0003] Although the swinging method can speed up the separation of the solidified layer and the release film, the photosensitive resin is easy to overflow from the material tank in the tilted state. To avoid the overflow of the photosensitive resin, it is necessary to increase the depth of the material tank or reduce the liquid volume of the material tank. At the same time, due to the swinging, the contact area between the photosensitive resin and the air is expanded, which makes it easy for air to mix into the photosensitive resin, affecting the printing quality of the product model.

[0004] Although the rotation method can also speed up the separation of the solidified layer and the release film, the separation of the solidified layer and the release film can only be completed by lifting the printing platform during the separation process. When printing each product model, the printing platform needs to reciprocate at least dozens of times. Taking the commonly used single solidified layer thickness of 0.05mm as an example, a product model with a height of 10mm needs to be printed at least 200 times. The frequent reciprocating motion of the printing platform is easy to cause wear to the ball screw and the screw nut, resulting in a decrease in printing accuracy and a reduction in the service life of the printing equipment.

[0005] Therefore, how to speed up the separation of the curing 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 is still a problem that needs to be solved in the development of top-pull light-curing 3D technology. Summary of the invention

[0006] In order to solve at least some of the above problems, the present application first proposes a top-pull light-curing 3D printer, which includes a workbench, on the top plate of which a transmission mechanism, a slewing bearing and a driving motor are installed; the transmission mechanism has a printing platform that can reciprocate in the vertical direction; the driving motor is a servo motor;

[0007] The slewing bearing comprises an outer ring and an inner ring which are connected together by balls. The central axis of the slewing bearing extends in the vertical direction. The outer ring is fixed on the workbench. The output shaft of the driving motor is connected to the inner ring. The driving motor can drive the inner ring to rotate. The lifting tube is threadedly engaged with the inner side of the inner ring. The lifting tube is limited to reciprocating in the vertical direction only and cannot rotate relative to the outer ring. The LCD screen is installed on the top of the lifting tube.

[0008] A sleeve is fixed on the outer ring, and the sleeve is coaxially arranged with the inner ring. The material groove 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 groove 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 inner ring, and the guide rod is slidably inserted into the guide hole.

[0009] The material 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 material trough is located at the first working position, the lifting tube is located at the third working position; when the material trough is located at the second working position, the lifting tube is located at the fourth working position; when the driving motor drives the inner ring to rotate, the material 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;

[0010] 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 second 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.

[0011] In the present application, the material trough and the LCD screen are both mounted on a slewing bearing, and when the inner ring of the slewing bearing rotates, the material trough and the lifting tube can be moved up and down synchronously, that is, the material trough and the LCD screen can be moved up and down synchronously. When the pull-up light-curing 3D printer in the present application is working, it is necessary to first arrange the material trough in the first working position and the lifting tube in the third working position, and then complete the printing of a solidified layer, and use the driving motor to make the material trough drop to the second working position and the lifting tube drop to the fourth working position, so that the solidified layer and the release film are separated, and then the material trough is raised to the first working position and the lifting tube is raised to the third working position to print the next solidified layer. Since the material trough rotates while moving up and down, the peeling speed of the solidified layer and the release film can be increased. Since the material trough moves down at the same time when the solidified layer and the release film are peeled off, the lifting height of the printing platform can be reduced. Since the printing platform is engaged with the ball screw through the screw nut, the wear of the ball screw and the screw nut can be reduced, so that the present application can improve the peeling speed of the solidified layer and the release film while also improving the service life of the equipment.

[0012] In specific use, the lowering 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 and the moving distance of the material trough and the LCD screen in the vertical direction, which can minimize the wear of the ball screw and the screw nut to increase the service life of the equipment.

[0013] Specifically, a limiting groove extending in the vertical direction is provided on the outer circumference of the lifting tube, and a limiting member is fixedly installed on the workbench, and the limiting member is inserted into the limiting groove. This design can limit the rotation of the lifting tube by the limiting member when the inner ring rotates, so that the lifting tube can only reciprocate in the vertical direction.

[0014] Furthermore, in order to avoid the restriction member from affecting the printing operation, one end of the restriction member is detachably fixed to the lower surface of the top plate, and the other end of the restriction member extends into the restriction groove. The restriction member is installed on the lower surface of the top plate so that the restriction member is located in the inner cavity of the workbench, which can effectively avoid the restriction member from affecting the printing operation.

[0015] Specifically, in order to make the material trough as close to the liquid crystal screen as possible, the upper surface of the liquid crystal screen should not be lower than the upper end surface of the lifting tube.

[0016] Furthermore, 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. This design can prevent the release film from being directly supported on the LCD screen. When the release film is directly supported on the LCD screen, the release film will rub against the LCD screen when the material trough rotates. After frequent friction, the light transmittance of the LCD screen will be reduced, thereby reducing the photocuring efficiency. Using light-transmitting glass to support the release film and spacing the light-transmitting glass and the LCD screen can effectively avoid mutual friction between the light-transmitting glass and the LCD screen when the material trough rotates, thereby reducing the light transmittance of both the light-transmitting glass and the LCD screen, thereby reducing the photocuring efficiency.

[0017] Furthermore, the printing platform has a central axis extending in the vertical direction, and in the horizontal direction, the central axis of the printing platform is at a distance 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 enables the bonding area of ​​the solidified layer and the release film to move relative to each other when the material trough rotates, so that the solidified layer and the release film can be peeled off smoothly. When the central axis of the printing platform coincides with the central axis of the material trough, when the material trough rotates, the area of ​​the release film located on the central axis will not move significantly with the solidified layer, and will also produce a vortex-like torsion with the central axis of the release film as the central axis, accelerating the failure of the release film.

[0018] Further, the pitch of the internal thread of the sleeve is the same as the pitch of the internal thread of the inner ring; or the pitch of the internal thread of the sleeve is smaller than the pitch of the internal thread of the inner ring. When the pitch of the internal thread of the sleeve is the same as the pitch of the internal thread of the inner ring, when the inner ring rotates, the lifting speed of the trough is the same as the lifting speed of the lifting tube, which can effectively prevent the collision between the LCD screen and the trough. When the pitch of the internal thread of the sleeve is smaller than the pitch of the internal thread of the inner ring, since the initial position of the trough is in the first working position and the initial position of the lifting tube is in the third working position during operation, the trough and the lifting tube are moved in the order of descending-ascending-descending-ascending, so the lifting speed of the lifting tube is greater than the lifting speed of the trough, and the LCD screen on the trough and the lifting tube will not collide with each other. However, in order to avoid the lifting tube from exceeding the third working position due to misoperation, causing the lifting tube to collide with the LCD screen, it is recommended to give priority to the solution in which the pitch of the internal thread of the sleeve is the same as the pitch of the internal thread of the inner ring. In order to make the trough and the lifting tube move downward or upward synchronously, the spiral direction of the internal thread of the sleeve and the internal thread of the inner ring are opposite.

[0019] Specifically, a gear is mounted on the output shaft of the driving motor, an outer gear ring is mounted at the lower part of the inner ring, and the gear is meshed with the outer gear ring; or a first pulley is mounted on the output shaft of the driving motor, a second pulley is arranged at the lower part of the inner ring, and the first pulley is wound around the first pulley and the second pulley via a belt. There is no difference between the above two ways of driving the inner ring to rotate by the driving motor, and they can be selected according to specific needs.

[0020] Secondly, the present application also discloses a light-curing 3D printing method, which is performed using any of the above-mentioned top-pull light-curing 3D printers, and the light-curing 3D printing method comprises the following steps:

[0021] (1) Adjust 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; immerse 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 complete the printing of the first solidified layer;

[0022] (2) The printing platform is lifted upward, the driving 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;

[0023] (3) The driving motor is reversed, the material trough rotates upward to 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;

[0024] (4) Repeat steps (2) and (3) to continue printing the solidified layer until the product model is printed.

[0025] In the present application, during the printing process of the product model, after each solidified layer is printed, the inner ring can be rotated by the driving motor, so that the material trough is lowered from the first working position to the second working position, and the lifting tube is lowered from the third working position to the fourth working position, and the material trough is rotated at the same time during the descent process, while accelerating the separation speed of the solidified layer and the release film. After the separation of the solidified layer and the release film is completed, the material trough is lifted upward while the printing platform is lowered. Since the reciprocating distance of the screw nut on the ball screw can be reduced, the wear between the screw nut and the ball screw can be reduced, thereby increasing the service life of the equipment.

[0026] Specifically, the number of revolutions of the trough is ≥ 0.2 revolutions. The number of revolutions of the trough does not need to exceed 1 revolution, and the number of revolutions of the trough can be controlled within 0.2-1 revolutions, and more preferably within 0.2-0.6 revolutions. When the trough rotates to a certain number of revolutions, the product model and the release film have been separated, and too many revolutions are not beneficial to the separation of the product model and the release film. When the trough rotates, the height of the trough descent is controlled between 2-5mm, and the separation height of the product model and the release film is generally controlled between 5-10mm. The present application controls the descent height of the trough between 2-5mm, which is 20-50% of the separation height of the product model and the release film. This can reduce the reciprocating distance of the screw nut on the ball screw, thereby reducing the wear between the screw nut and the ball screw, and increasing the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of an embodiment of the present application.

[0028] Figure 2 yes Figure 1 Center AA view.

[0029] Figure 3 yes Figure 1 Another state diagram of the accompanying drawing shown. DETAILED DESCRIPTION

[0030] The following first describes the top-pull light-curing 3D printer in this application. Figure 1 and Figure 2 The light-curing 3D printer includes a workbench 10, which includes a vertical wall 11 in a rectangular cylindrical shape extending in a vertical direction, a bottom plate 12 installed at the bottom of the vertical wall, and a top plate 13 installed at the top of the vertical wall.

[0031] A transmission mechanism is installed on the workbench, and the transmission mechanism includes a column 15, a lifting motor 21, and a ball screw 22. The column 15 is fixedly installed on the top plate of the workbench, and the lifting motor 21 is installed at the bottom of the column. The ball screw extends in the vertical direction. One end of the lifting arm 16 is engaged with the ball screw through a screw nut, and the other end of the lifting arm extends in the horizontal direction away from the ball screw and forms a free end. The printing platform 17 is installed on the free end. Driven by the lifting motor, the lifting arm 16 can move up and down along the ball screw and drive the printing platform to move up and down. The lifting motor 21 specifically adopts a servo motor, and the specific transmission mechanism can be learned from the prior art.

[0032] The slewing bearing 60 includes an outer ring 62 and an inner ring 61 which are connected together by a ball 63. The outer ring 62 is fixed to the top plate of the workbench by a locking bolt 64. The first center axis 311 of the slewing bearing 60 extends in the vertical direction. Specifically in this embodiment, in order to reduce the influence of the slewing bearing on the printing work, a step hole 19 is opened on the top plate. The step hole 19 is larger at the top and smaller at the bottom, so that the step hole has a step surface 191 facing upward, and the outer ring 62 is fixed on the step surface 191. The inner ring extends downward from the step hole, and an outer gear ring 66 is provided on the outer peripheral surface of the lower part of the inner ring.

[0033] The drive motor 71 is fixedly mounted on the step surface 191, and a gear 72 is mounted after the output shaft of the drive motor extends downward from the top plate, and the gear 72 is meshed with the outer gear ring. In this embodiment, the outer gear ring is processed separately and then fixed to the inner ring with bolts. It can be understood that in another embodiment, the outer gear ring can also be formed integrally on the inner ring. Through the gear and the outer gear ring, the drive motor can drive the inner ring to rotate.

[0034] It can be understood that in another embodiment, the output shaft of the driving motor and the inner ring can also be connected by a belt connection, specifically, a first pulley is installed on the output shaft of the driving motor, a second pulley is installed at the lower part of the inner ring, and then a belt is wrapped around the first pulley and the second pulley, so that the driving motor can drive the inner ring to rotate through the belt. The specific connection method of the belt can adopt the existing mature technology.

[0035] A first internal thread is provided on the inner circumference of the inner ring 61, and a first external thread is provided on the outer wall of the lifting tube 41. The lifting tube 41 is meshed with the first internal thread of the inner ring 61 through the first external thread, so that the lifting tube 41 is threadedly meshed on the inner side of the inner ring 61, and the lifting tube 41 is limited to only be able to reciprocate in the vertical direction and cannot rotate relative to the outer ring. In this embodiment, a limiting groove 43 extending in the vertical direction is provided on the outer circumference of the lifting tube, and a limiting member 69 is fixedly installed on the workbench, and the limiting member is inserted into the limiting groove 43. The limiting member 69 is specifically a steel plate, and one end of the limiting member 69 is detachably fixed to the lower surface of the top plate 13 by bolts, and the other end of the limiting member 69 passes over the inner ring and extends into the limiting groove. When the driving motor drives the inner ring 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 outer ring.

[0036] In order to prevent the lifting tube 41 from falling off the inner ring 61 downward, 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 inner ring, thereby preventing the lifting tube from falling off the inner ring 61 downward.

[0037] 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 surface of the lifting tube. It can be understood that in other embodiments, the upper surface of the LCD screen can also exceed the upper end surface of the lifting tube. However, the height of the upper surface of the LCD screen exceeding the upper end surface 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.

[0038] A sleeve 36 is welded to the upper end face of the outer ring 62, and the sleeve is coaxially arranged with the inner ring, and the inner wall of the sleeve has a second internal thread. The material trough 30 has a ring-shaped trough wall 31, and a light-transmitting glass 33 is installed at the bottom of the trough wall, and a release film is laid on the upper surface of the light-transmitting glass. A second external thread is arranged on the outer peripheral surface of the trough wall, and the material trough is screwed on the second internal thread through the second external thread, so that the thread of the trough wall is engaged with the inner side of the sleeve. A guide hole 32 extending in the vertical direction is arranged in the body of the trough wall, and a guide rod 37 is fixedly installed on the inner ring, and the guide rod is slidably penetrated in the guide hole. In this embodiment, when installing the material trough, the material trough is first screwed into the sleeve, and after the distance between the material trough and the inner ring of the slewing bearing 60 reaches the set distance, the guide rod is then inserted into the guide hole, and the guide rod is screwed into the bolt hole at the top of the inner ring. The set distance is determined according to the height to be lowered of the material trough.

[0039] It can be understood that in another embodiment, a flange can be installed at the lower end of the sleeve, and then the flange can be fixed to the outer ring with bolts.

[0040] 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 driving motor drives the inner ring 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.

[0041] Please also see Figure 1 and Figure 3 , Figure 1 In the process, the trough is in the first working position, and the lifting tube is in the third working position. Figure 3 In the embodiment, the material trough is in the second working position, and the lifting tube is in the fourth working position. When the material trough 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 trough to perform printing. When the material trough is in the second working position and the lifting tube is in the fourth working position, the product model on the printing platform and the release film of the release film are in a separated state. When the driving motor 71 drives the inner ring 61 to rotate, the material trough can be rotated downward from the first working position to the second working position, and the lifting tube can be synchronously moved downward from the third working position to the fourth working position, or the material trough can be rotated upward from the second working position to the first working position, and the lifting tube can be synchronously moved upward from the fourth working position to the third working position.

[0042] In order to avoid friction between the light-transmitting glass and the liquid crystal screen when the material trough is rotating, which causes wear on both, in this embodiment, when the material trough is in the first working position and the lifting tube is in the third working position, there is a gap of 0.5mm between the light-transmitting glass and the liquid crystal screen. The distance between the light-transmitting glass and the liquid crystal screen should not be too large, preferably 0.2-1mm, and can also be 0.2mm, 0.4mm, 0.8mm or 1mm, and of course other distances between 0.2-1mm. An ultraviolet light system 14 is installed in the inner cavity of the workbench, and the ultraviolet light emitted by the ultraviolet light system can irradiate the liquid crystal screen. In this embodiment, the ultraviolet light system adopts existing mature technology and will not be described in detail.

[0043] In order to reduce the interference of the guide rod on the work, in this embodiment, when the trough is in the first working position and the lifting tube is in the third working position, the top of the guide rod is lower than the top of the trough wall of the trough. The guide rod in this embodiment is a cylindrical rod. To facilitate screwing the guide rod, a regular hexagonal screw hole is provided on the top of the guide rod. The hexagonal wrench can be inserted into the screw hole to screw the guide rod into the threaded hole on the top of the inner ring of the slewing bearing 60, or to screw the guide rod out of the threaded hole.

[0044] The printing platform has a second central axis 171 extending in the vertical direction. Since the sleeve is coaxially arranged with the inner ring, the material trough is screwed on the sleeve, so that the material trough is coaxially arranged with the inner ring, that is, the material trough is coaxially arranged with the slewing bearing, and the first central axis 311 of the slewing bearing 60 is also the central axis of the material trough. In the horizontal direction, the first central axis and the second central axis have a distance H. In this embodiment, the distance H between the first central axis and the second central axis in the horizontal direction is 5mm. In other embodiments, the distance H between the first central axis and the second central axis in the horizontal direction is preferably 5-15mm. The specific distance H can be selected according to the size of the material trough. The larger the material trough, the larger the distance H between the first central axis and the second central axis in the horizontal direction. However, there is no special requirement in the specific selection. Figure 2 In the figure, for clarity, the second central axis 171 and the first central axis 311 are both represented by a small circle, and Figure 2 In the figure, the position of the printing platform in the trough is indicated by a dotted line.

[0045] The purpose of setting the first central axis and the second central axis at intervals is to extend the service life of the release film. When the first central axis and the second central axis overlap, when the trough rotates, the point on the first central axis is actually in a stationary state. Driven by the product model, the release film will produce a vortex-like twist with the first central axis as the central axis, accelerating the failure of the release film. After the first central axis and the second central axis are set at intervals, when the trough rotates, the product model can move as a whole with the release film, avoiding the above-mentioned vortex-like twist, which is more conducive to the separation of the product model and the release film, and ensuring the service life of the release film.

[0046] 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 inner ring, so that when the inner ring rotates, the lifting speed of the 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 also be made smaller than the pitch of the first internal thread of the inner ring. At this time, the lifting speed of the trough is smaller than the lifting speed of the lifting tube. Since the initial position of the trough is in the first working position and the lifting tube is in the third working position during operation, the trough and the lifting tube move in the order of descending-ascending-descending-ascending. Therefore, the trough and the LCD screen on the lifting tube will not collide with each other due to the lifting speed of the lifting tube being greater than the lifting speed of the trough. However, in order to avoid the lifting tube from exceeding the third working position upward due to misoperation, causing the collision between the trough and the LCD screen, it is recommended to preferentially adopt the solution that the pitch of the second internal thread of the sleeve is the same as the pitch of the first internal thread of the inner ring. In order to make the trough and the lifting tube move downward or upward synchronously, the spiral direction of the second internal thread of the sleeve is opposite to that of the first internal thread of the inner ring.

[0047] The following is an explanation of the light-curing 3D printing method in the present application. The light-curing 3D printing method is performed using the above-mentioned top-pull light-curing 3D printer. The light-curing 3D printing method includes the following steps:

[0048] (1) Adjust 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; immerse 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 complete the printing of the first solidified layer;

[0049] (2) The printing platform is lifted upward, the driving 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;

[0050] (3) The driving motor is reversed, the material trough rotates upward to 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;

[0051] (4) Repeat steps (2) and (3) to continue printing the solidified layer until the product model is printed.

[0052] To maximize the printing efficiency, when the printing platform is lifted upward, the drive motor is started to rotate forward synchronously, and when the drive motor is reversed, the printing platform is lowered synchronously. In this embodiment, during the process of peeling the solidified layer from the release film, the number of turns of the material trough is 0.4 turns.

Claims

1. A top-pull light-curing 3D printer, characterized in that: It comprises a workbench, on the top plate of which a transmission mechanism, a slewing bearing and a driving motor are installed; the transmission mechanism has a printing platform capable of reciprocating in the vertical direction; the driving motor is a servo motor; The slewing bearing comprises an outer ring and an inner ring which are connected together by balls. The central axis of the slewing bearing extends in the vertical direction. The outer ring is fixed on the workbench. The output shaft of the driving motor is connected to the inner ring. The driving motor can drive the inner ring to rotate. The lifting tube is threadedly engaged with the inner side of the inner ring. The lifting tube is limited to reciprocating in the vertical direction only and cannot rotate relative to the outer ring. The LCD screen is installed on the top of the lifting tube. A sleeve is fixed on the outer ring, and the sleeve is coaxially arranged with the inner ring. The material groove 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 groove 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 inner ring, and the guide rod is slidably inserted into the guide hole. The material 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 material trough is located at the first working position, the lifting tube is located at the third working position; when the material trough is located at the second working position, the lifting tube is located at the fourth working position; when the driving motor drives the inner ring to rotate, the material 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 second 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 top-pull light-curing 3D printer 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, and the limiting member is inserted into the limiting groove.

3. The top-pull light-curing 3D printer according to claim 2, characterized in that: One end of the limiting member is detachably fixed to the lower surface of the top plate, and the other end of the limiting member extends into the limiting groove.

4. The top-pull light-curing 3D printer 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 top-pull light-curing 3D printer 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 top-pull light-curing 3D printer 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 top-pull light-curing 3D printer 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 inner ring; or the pitch of the internal thread of the casing is smaller than the pitch of the internal thread of the inner ring.

8. The top-pull light-curing 3D printer according to claim 1, characterized in that: A gear is mounted on the output shaft of the driving motor, an outer gear ring is mounted on the lower part of the inner ring, and the gear is meshed with the outer gear ring; or A first pulley is installed on the output shaft of the driving motor, and a second pulley is arranged at the lower part of the inner ring. The first pulley is wrapped around the first pulley and the second pulley via a belt.

9. A light-curing 3D printing method, characterized in that: The top-down light-curing 3D printer according to any one of claims 1 to 8 is used, and the light-curing 3D printing method comprises the following steps: (1) Adjust 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; immerse 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 complete the printing of the first solidified layer; (2) The printing platform is lifted upward, the driving 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 driving motor is reversed, the material trough rotates upward to 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.

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

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