Printing method of photocuring 3D printing device, device and storage medium

Abstract

A printing method of a photocuring 3D printing device, a device and a storage medium. The method comprises: by means of autofocus, determining a first position of a resin tank moving mechanism in the vertical direction when the lower surface of a film of a film tensioning assembly is located on a focusing plane of a projection lens; controlling the distance between the focusing plane and a forming surface of a printing platform to be within a preset distance range, and determining a second position of a platform moving mechanism in the vertical direction at this moment; and performing printing on the basis of the first position and the second position.

Description

Printing method, device and storage medium of light-curing 3D printing device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 1, 2023, with application number 202311450539.2, and invention name “Printing method, device and storage medium for photocuring 3D printing device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of 3D printing technology, and in particular to a printing method of a light-curing 3D printing device, a light-curing 3D printing device, and a storage medium. Background Art

[0003] Stereolithography 3D printing methods can be divided into SLA (Stereo Lithography Apparatus) and DLP (Digital Light Processing).

[0004] Whether using SLA or DLP stereolithography, the photopolymerization reaction must occur on the focal plane of the projection lens. During the photopolymerization and curing process of each layer, the surface of the photosensitive resin to be formed must remain on the focal plane and coincide with the lower surface of the film. However, when focusing, the focal plane of current stereolithography 3D printing devices often fluctuates between the upper and lower surfaces of the film. This results in low focusing accuracy, making it easy for the optical projection to lose focus and making it impossible to stably print high-precision, complex structures.

[0005] Summary of the Invention

[0006] Based on this, the present application provides a printing method of a light-curing 3D printing device, a light-curing 3D printing device and a storage medium, which can improve focusing accuracy and printing accuracy.

[0007] In a first aspect, the present application provides a printing method for a photocuring 3D printing device, the device comprising: a film assembly, a resin tank, a resin tank moving mechanism, a printing platform, a platform moving mechanism, and a projection lens, the film assembly being disposed on the resin tank, the resin tank being movable in a vertical direction under the drive of the resin tank moving mechanism, the film assembly moving with the resin tank, and the printing platform being movable in the vertical direction under the drive of the platform moving mechanism, the method comprising:

[0008] Determining, by means of autofocus, that the resin tank moving mechanism is in a first position in the vertical direction when the lower surface of the film of the stretch film assembly is in a focal plane of the projection lens;

[0009] controlling the distance between the focusing plane and the molding surface of the printing platform to be within a preset distance range, and determining a second position of the platform moving mechanism in the vertical direction at this time;

[0010] Printing is performed according to the first position and the second position.

[0011] In a second aspect, the present application provides a photocuring 3D printing device, comprising: a film stretching assembly, a resin tank, a resin tank moving mechanism, a printing platform, a platform moving mechanism, and a projection lens, wherein the film stretching assembly is arranged on the resin tank, and the resin tank can move in a vertical direction driven by the resin tank moving mechanism, the film stretching assembly moves following the resin tank, and the printing platform can move in the vertical direction driven by the platform moving mechanism, and the device also comprises: a processor and a memory, the memory is also used to store a computer program, and the processor is used to execute the computer program and, when executing the computer program, implement the printing method of the photocuring 3D printing device as described above.

[0012] In a third aspect, the present application provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor implements the printing method of the light-curing 3D printing device as described above.

[0013] In the embodiment of the present application, the lower surface of the film is placed in the focus plane during autofocusing, and the first position of the resin tank moving mechanism in the vertical direction is determined at this time. When the printing thickness (i.e., the distance between the focus plane and the molding surface of the printing platform) is controlled within a preset distance range, the second position of the platform moving mechanism in the vertical direction is determined at this time. Therefore, when printing according to the first and second positions, the lower surface of the film coincides with the focus plane when the resin tank moving mechanism is in the first position, and the molding surface of the printing platform is also moved downward by a preset distance based on the focus plane when the platform moving mechanism is in the second position, thereby controlling the printing thickness. That is, the lower surface of the film and the molding surface of the printing platform are both based on the focus plane. By controlling the distance between the lower surface of the film and the molding surface of the printing platform, the required printing layer thickness is controlled, thereby achieving high control of the thickness of each layer of the printed sample. At the same time, after high-precision focusing, optical projection defocus can be avoided as much as possible, thereby improving printing accuracy and stably printing high-precision, complex structure prints. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG1 is a schematic flow chart of an embodiment of a printing method of a light-curing 3D printing device of the present application;

[0015] FIG2 is a schematic structural diagram of an embodiment of a light-curing 3D printing device of the present application;

[0016] FIG3 is a schematic flow chart of another embodiment of a printing method of a light-curing 3D printing device of the present application;

[0017] FIG4 is a schematic flow chart of another embodiment of a printing method of a light-curing 3D printing device of the present application;

[0018] FIG5 is a schematic flow chart of another embodiment of a printing method of a light-curing 3D printing device of the present application;

[0019] FIG6 is a schematic flow chart of another embodiment of a printing method of a light-curing 3D printing device of the present application;

[0020] FIG7 is a schematic flow chart of another embodiment of a printing method of a light-curing 3D printing device of the present application;

[0021] FIG8 is a schematic diagram of an embodiment of a preset standard image used in the printing method of the light-curing 3D printing device of the present application;

[0022] FIG9 is a schematic diagram of spot indexing using step-size doubling in the printing method of the light-curing 3D printing device of the present application;

[0023] FIG10 is a schematic diagram of multi-point comparison and climbing focusing in the printing method of the light-curing 3D printing device of the present application.

[0024] Description of main components and symbols:

[0025] 2. Optical machine; 3. Resin tank moving mechanism; 31. First support shaft; 32. Mounting plate; 4. Focusing mechanism; 43. Projection lens; 44. Camera; 45. Spectrometer; 5. Printing platform; 6. Platform moving mechanism; 61. Second support shaft; 62. Slide plate; 8. Film stretching assembly; 9. Support plate; 10. Driving mechanism; 11. Resin tank. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, combined, or partially merged, so the actual execution order may vary depending on the actual situation.

[0028] The photopolymerization reaction in stereolithography 3D printing occurs on the focal plane of the projection lens. The surface of the photosensitive resin should always be placed on this focal plane, and during the photopolymerization and curing process of each layer, the surface of the photosensitive resin should remain on this focal plane and coincide with the lower surface of the film. However, when focusing on current stereolithography 3D printing devices, the focal plane often fluctuates between the upper and lower surfaces of the film. This results in low focusing accuracy, making optical projection prone to loss of focus and making it impossible to reliably print high-precision, complex structures.

[0029] In the embodiment of the present application, the lower surface of the film is placed in the focus plane during autofocusing, and the first position of the resin tank moving mechanism in the vertical direction is determined at this time. When the printing thickness (i.e., the distance between the lower surface of the film and the molding surface of the printing platform) is controlled within a preset distance range, the second position of the platform moving mechanism in the vertical direction is determined at this time. Therefore, when printing according to the first and second positions, the lower surface of the film coincides with the focus plane when the resin tank moving mechanism is in the first position, and the molding surface of the printing platform is also moved downward by a preset distance based on the focus plane when the platform moving mechanism is in the second position, thereby controlling the printing thickness. That is, the lower surface of the film and the molding surface of the printing platform are both based on the focus plane. By controlling the distance between the lower surface of the film and the molding surface of the printing platform, the required printing layer thickness is controlled, thereby achieving high control of the thickness of each layer of the printed sample. At the same time, after high-precision focusing, optical projection defocus can be avoided as much as possible, thereby improving printing accuracy and stably printing high-precision, complex structure prints.

[0030] The method of the embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0031] Please refer to FIG1 , which is a flow chart of a printing method of an embodiment of the light-curing 3D printing device of the present application.

[0032] 2 , the photocuring 3D printing device of the embodiment of the present application includes: a film stretching assembly 8, a resin tank 11, a resin tank moving mechanism 3 (the resin tank moving mechanism 3 in the figure includes a first support shaft 31 and a mounting plate 32), a printing platform 5, a platform moving mechanism 6 (the platform moving mechanism 6 in the figure includes a second support shaft 61 and a slide 62), and a projection lens 43. It should be noted that in this embodiment, the first support shaft 31 is arranged on the side of the mounting plate 32, flush with the mounting plate 32 or higher than the mounting plate 32. The first support shaft 31 can also be arranged on the top of the mounting plate 32 or at the bottom of the mounting plate 32, or other arrangements that can drive the movement of the resin tank 11 are all acceptable.

[0033] The resin tank 11 is used to contain liquid photosensitive resin; the resin tank moving mechanism 3 is used to carry and drive the resin tank 11 to move in the vertical direction.

[0034] The film assembly 8 is mounted on the resin tank 11. Driven by the resin tank moving mechanism 3, the resin tank 11 is vertically movable. The film assembly 8 follows the movement of the resin tank 11. Therefore, vertical movement of the resin tank moving mechanism 3 drives the film assembly 8 to move vertically, thereby changing the vertical position of the lower surface of the film of the film assembly 8. The film assembly 8 can use its membrane to quickly flatten the liquid surface of the photosensitive resin to be printed, significantly shortening the time it takes for the photosensitive resin to level, thereby improving product molding efficiency.

[0035] The printing platform 5 is movable in the vertical direction driven by the platform moving mechanism 6. Therefore, the vertical movement of the platform moving mechanism 6 can drive the printing platform 5 to move in the vertical direction, thereby changing the vertical position of the molding surface of the model on the printing platform 5.

[0036] In some embodiments, the photo-curing 3D printing device can be divided into: a light source and projection system, a ranging, leveling and autofocus system, and a mechanical and electrical control system.

[0037] The light source illumination and projection system may include: an optical engine 2 (e.g., a DLP optical engine), a camera 44 (e.g., an industrial camera), a beam splitter 45, a projection lens 43, and an optical path system connection structure. The light source driver and spatial light modulator are built into the optical engine 2. The optical engine projects ultraviolet light onto the beam splitter 45, which then reflects it to the projection lens 43. The light path of the light source projected by the optical engine 2 is perpendicular to the projection path of the camera 44 and the projection lens 43. The beam splitter 45 is installed at a 45-degree angle on the centerline of the optical path between the camera 44 and the projection lens 43. The projection lens 43, camera 44, and beam splitter 45 constitute the focusing mechanism 4.

[0038] It should be noted that the lower surface of the film in this application should be understood as the side of the film away from the focusing mechanism 4, that is, the side of the film overlapping with the surface of the photosensitive resin to be formed, and the upper surface of the film should be understood as the side of the film close to the focusing mechanism 4, that is, the side of the film away from the surface of the photosensitive resin to be formed.

[0039] In some embodiments, the light source may be a DLP (Digital Light Processing) light source. By adopting a DLP light source, the precision of the product may be further improved.

[0040] The laser ranging, leveling, and autofocus system may include: an optical machine 2, a beam splitter 45, a projection lens 43, a camera 44, and a high-precision ranging device (e.g., a laser ranging device) and their connection structure. The high-precision ranging device is mounted outside the projection lens, parallel to the projection optical path. The high-precision ranging device detects the relative position data of the printing platform, the liquid level of the photosensitive resin, and the film surface of the film stretching mechanism. Simultaneously, the camera captures the projected image (i.e., the light spot in the projection area) after digital light processing and feeds it back to the control system of the printing device. The control system sends instructions to precisely control the height between the molding surface of the printing platform and the film surface of the film stretching mechanism (i.e., the print thickness, the print layer thickness), thereby achieving the purpose of accurately controlling the overall height in the vertical direction (i.e., the Z direction) and the thickness of each print layer.

[0041] Among them, the mechanical platform and electrical control system include a mechanical platform subsystem and an electrical control subsystem. The mechanical platform subsystem may include: an XY motion platform unit, a platform moving mechanism 6 (i.e., the printing platform Z1 axis), and a resin tank moving mechanism 3 (i.e., the resin tank Z2 axis). The function of the printing platform Z1 axis is to drive the printing platform to move up and down in the vertical direction with high precision; the function of the resin tank Z2 axis is to drive the resin tank to move up and down in the vertical direction with high precision; and autofocus is achieved through the relative movement of the dual Z axes (Z1 axis, Z2 axis). The electrical control subsystem may include: optical and mechanical control, motion control, detection control, user interface, image slicing and other parts, and the system control of the device is achieved through an industrial computer or PLC (Programmable Logic Controller) or a single-chip microcomputer, combined with the upper computer software control.

[0042] The device may further include a support plate 9 and a drive mechanism 10 . The support plate 9 may be used to support the resin tank moving mechanism 3 and the platform moving mechanism 6 . The drive mechanism 10 is disposed at the bottom end of the support plate 9 and may be used to drive the support plate 9 to slide.

[0043] The printing method of the light-curing 3D printing device includes:

[0044] Step S101: determining, by auto-focusing, a first position of the resin tank moving mechanism in the vertical direction when the lower surface of the film of the stretch film assembly is located at a focal plane of the projection lens.

[0045] The film of the stretch film assembly has two surfaces, upper and lower. The liquid level of the photosensitive resin actually contacts the lower surface of the film. In related art, during autofocus, the focal plane of the projection lens fluctuates between the upper and lower surfaces of the film, resulting in low focusing accuracy. The present embodiment directly aligns the focal plane of the projection lens with the lower surface of the film during autofocus, placing the lower surface of the film within the focal plane of the projection lens. This ensures that the resin tank moving mechanism is in its first vertical position.

[0046] It should be noted that if the printing accuracy requirement is not high, the resin tank moving mechanism can be directly controlled to be in a fixed first position during printing; if the printing accuracy requirement is high, the first position of the resin tank moving mechanism in the vertical direction when the lower surface of the film of the stretch film assembly is in the focal plane of the projection lens needs to be re-determined each time printing is performed.

[0047] To align the focal plane of the projection lens with the bottom surface of the film, the top and bottom surfaces of the film must first be automatically identified. This is done by aligning the focal plane of the projection lens with the bottom surface of the film. Methods for automatically identifying the top and bottom surfaces of the film include, but are not limited to, using a spectral confocal sensor, or by combining the order in which light spots appear on the top and bottom surfaces of the film with the movement direction of the resin tank movement mechanism.

[0048] Step S102: controlling the distance between the focus plane and the molding surface of the printing platform to be within a preset distance range, and determining the second position of the platform moving mechanism in the vertical direction at this time.

[0049] The distance between the focus plane and the molding surface of the printing platform—that is, the distance between the lower surface of the film and the molding surface of the printing platform when the lower surface of the film is in the focus plane—is the print thickness. If this thickness is too thick or too thin, it will affect the printing effect and may even prevent the printed photosensitive resin from adhering firmly to the printing platform, resulting in printing failure. Therefore, it is necessary to control this distance within a preset distance range and determine the second vertical position of the platform moving mechanism at this time (i.e., when the distance between the focus plane and the molding surface of the printing platform is within the preset distance range).

[0050] It should be noted that if the printing accuracy requirement is not high, the platform moving mechanism can be directly controlled to be in a fixed second position during printing; if the printing accuracy requirement is high, the second position of the platform moving mechanism in the vertical direction needs to be re-determined each time printing occurs when the distance between the focusing plane and the molding surface of the printing platform is within a preset distance range.

[0051] There are many specific ways to control the distance between the focusing plane and the molding surface of the printing platform within a preset distance range, such as controlling it by measuring it with a distance sensor; or controlling it by precisely controlling the position of the molding surface of the printing platform when the first position and the preset distance range are known; and so on.

[0052] It should be noted that there is no obvious order between step S101 and step S102.

[0053] In some embodiments, step S102 may be performed first, and then step S101 may be performed. After the second position and the first position are determined in sequence, printing may be performed, thereby reducing the number of operation steps.

[0054] Step S103: Printing is performed according to the first position and the second position.

[0055] In the embodiment of the present application, the lower surface of the film is placed in the focus plane during autofocusing, and the first position of the resin tank moving mechanism in the vertical direction is determined at this time. When the printing thickness (i.e., the distance between the focus plane and the molding surface of the printing platform) is controlled within a preset distance range, the second position of the platform moving mechanism in the vertical direction is determined at this time. Therefore, when printing according to the first and second positions, the lower surface of the film coincides with the focus plane when the resin tank moving mechanism is in the first position, and the molding surface of the printing platform is also moved downward by a preset distance based on the focus plane when the platform moving mechanism is in the second position, thereby controlling the printing thickness. That is, the lower surface of the film and the molding surface of the printing platform are both based on the focus plane. By controlling the distance between the lower surface of the film and the molding surface of the printing platform, the required printing layer thickness is controlled, thereby achieving high control of the thickness of each layer of the printed sample. At the same time, after high-precision focusing, optical projection defocus can be avoided as much as possible, thereby improving printing accuracy and stably printing high-precision, complex structure prints.

[0056] Referring to Figure 3, in some embodiments, step S101, determining by autofocus that the lower surface of the film of the stretch film assembly is in the first position of the resin tank moving mechanism in the vertical direction when the lower surface of the film is in the focal plane of the projection lens, may include: sub-step S1011 and sub-step S1012.

[0057] Sub-step S1011: Initially focus the upper and lower surfaces of the membrane of the stretch film assembly according to the light spot in the projection area. During the initial focusing process, determine the light spot corresponding to the lower surface of the membrane based on the change trend of the clarity of the light spot twice before and after and the moving direction of the resin tank moving mechanism.

[0058] Sub-step S1012: precisely focusing the lower surface of the film according to the light spot corresponding to the lower surface of the film, and determining the first position of the resin tank moving mechanism in the vertical direction when the lower surface of the film is in the focusing plane.

[0059] Since the light spot appears twice respectively when focusing on the upper and lower surfaces of the film, and the change trend of the clarity of the light spot is regular, combined with the moving direction of the resin tank moving mechanism when the two light spots appear, it can be determined which light spot corresponds to the projection area of ​​the upper surface of the film and which light spot corresponds to the projection area of ​​the lower surface of the film. Therefore, initial focusing can be performed first. During the initial focusing process, the light spot corresponding to the lower surface of the film is determined according to the change trend of the clarity of the light spot twice before and after and the moving direction of the resin tank moving mechanism. Then, the lower surface of the film is precisely focused on the light spot corresponding to the lower surface of the film. Through precise focusing, the first position of the resin tank moving mechanism in the vertical direction when the lower surface of the film is in the focusing plane can be accurately determined. When identifying the upper and lower surfaces of the film, only the change pattern of the clarity of the light spot is found through initial focusing. In this way, time for identifying the upper and lower surfaces of the film can be saved, and it is simple and convenient and does not require any hardware costs.

[0060] 4 , in some embodiments, sub-step S1011 , before initially focusing the upper and lower surfaces of the membrane of the stretch film assembly according to the light spot in the projection area, may further include: step S104 , step S105 , and step S106 .

[0061] Step S104: controlling the light source to project a preset standard image at a preset default energy value.

[0062] Step S105: When it is determined that there is no light spot in the projection area, the light source is controlled to project the preset standard image again with a preset maximum energy value.

[0063] Step S106: When it is determined again that there is no light spot in the projection area, a light spot search is performed by means of a light spot index.

[0064] The energy value of a light source (UV light) is measured in mJ / cm². The energy value can be determined by multiplying the light intensity (mW / cm²) by the time (seconds). When the projection area of ​​the same platform is located on the focal plane, the clarity and brightness of the light spot will vary under different light intensities. Generally, within a certain range, the greater the light intensity, the clearer and brighter the light spot. When the light intensity exceeds a certain level, the change in clarity and brightness of the light spot in the projection area becomes less significant. When the projection areas of different platforms are located on the focal plane, the clarity and brightness of the light spot will also vary under the same light intensity.

[0065] Therefore, in order to avoid the absence of light spots in the projection area due to insufficient energy value of the light source, the energy value of the light source will be increased when the light source projects a preset standard picture with a preset default energy value and there is no light spot in the projection area. Increasing the energy value of the light source to the preset maximum energy value can quickly determine whether the absence of light spots in the projection area is caused by insufficient energy value of the light source. If it is caused by insufficient energy value of the light source, then generally light spots will appear when the light source is projected again with the preset maximum energy value. If it is not caused by insufficient energy value of the light source, then no light spots will appear even if the light source is projected again with the preset maximum energy value.

[0066] In some embodiments, the preset standard picture may be a 100*100 pixel calibration picture, and the calibration picture may be a calibration picture including a plurality of grids.

[0067] One way to determine whether there is a light spot in the projection area is to capture an image of the projection area with a camera, filter the image, and analyze the image to determine whether there is a light spot in the projection area.

[0068] If the light source is projected with a preset default energy value and it is determined that there is a light spot in the projection area, initial focusing can be performed. If the light source is projected with a preset default energy value and it is determined that there is no light spot in the projection area, the light source is projected again with a preset maximum energy value. When it is determined that there is still no light spot in the projection area after re-projection, the problem of insufficient energy value of the light source is eliminated, and then a light spot search is performed by means of a light spot index. Initial focusing can be performed after the light spot is found.

[0069] It is still difficult to find the light spot when performing a light spot search when the energy value of the light source is insufficient. By eliminating the problem of insufficient energy value of the light source and then performing the light spot search, on the one hand, the probability of failure of the light spot search can be minimized, and on the other hand, the specific reason why there is no light spot in the projection area can be determined more specifically, making the light spot search more targeted and the probability of finding the light spot greater.

[0070] 5 , in some embodiments, step S106 , performing the light spot search by light spot indexing, may further include sub-steps S1061 and S1062 .

[0071] Sub-step S1061: Control the resin tank moving mechanism to move rapidly by alternating forward and reverse directions in the first step with double the length.

[0072] Sub-step S1062: During the doubly rapid movement, determine whether there is a light spot in the projection area according to the image stream data of the projection area from the camera.

[0073] In the embodiment of the present application, when performing light spot indexing, the resin tank moving mechanism adopts a forward and reverse alternating first step with double the length to move quickly, so that the approximate position of the resin tank moving mechanism when there is a light spot can be quickly found, thereby saving the time of light spot indexing.

[0074] When determining whether there is a light spot in the projection area, compared with the method of obtaining pictures by taking pictures with a camera in related technologies, the camera of the embodiment of the present application performs real-time retrieval of the projection area (i.e., real-time shooting) and feedback to obtain image stream data, and determines whether there is a light spot in the projection area by analyzing the image stream data. Because the image stream data is real-time data of the projection area, it can determine whether there is a light spot in the projection area more in real time and accurately.

[0075] In some embodiments, the method may further include: step S107.

[0076] Step S107: When it is determined that there is no light spot in the entire projection area within the upper and lower limit movement ranges of the resin tank moving mechanism, the light spot search is exited and a prompt message is issued, wherein the prompt message is used to indicate that there may be a problem with the camera or optical machine.

[0077] If, during the light spot search, no light spot is found in the projection area during the entire movement within the upper and lower limit movement ranges of the resin tank moving mechanism, it is meaningless to continue the search. Therefore, the light spot search is exited and a prompt message is issued. The prompt message is used to indicate that there may be a problem with the camera or optical machine.

[0078] If a light spot is found in the projection area, initial focusing can be performed.

[0079] 6 , in some embodiments, sub-step S1011 , performing initial focusing on the upper and lower surfaces of the membrane of the stretch film assembly according to the light spot in the projection area, may include: sub-step S10111 , sub-step S10112 , and sub-step S10113 .

[0080] Sub-step S10111: Control the resin tank moving mechanism to move at a low speed with a second step length doubled in alternating forward and reverse directions.

[0081] Sub-step S10112: during the doubled low-speed movement, when the clarity of the light spot changes in the previous and subsequent times, the clarity gradually increases, reaches the highest clarity, and then gradually decreases, determining the moving direction of the resin tank moving mechanism.

[0082] Sub-step S10113: When the resin tank moving mechanism moves downward during the two occurrences of the light spots, the projection area where the light spot that appears later is located is determined to be the lower surface of the film. When the resin tank moving mechanism moves upward during the two occurrences of the light spots, the projection area where the light spot that appears earlier is located is determined to be the lower surface of the film.

[0083] Since the approximate position of the resin tank moving mechanism is known based on the light spot in the projection area during the spot search, initial focus adjustment requires back-and-forth adjustment near that approximate position. Adjustment should be slow, using a second, alternating forward and reverse step length and doubled-speed movement. Specific adjustments can be made based on film thickness. In some embodiments, the second step length is smaller than the first step length.

[0084] During the initial focus, the projection area fluctuates between the upper and lower surfaces of the film. When the resin tank moving mechanism moves, the trend near a film surface may be close to the film surface, on the film surface, and away from the film surface. At this time, the clarity of the light spot in the projection area tends to change as follows: the clarity gradually increases (close to the film surface), the clarity is the highest (on the film surface), and the clarity gradually decreases (away from the film surface). Because the resin tank moving mechanism moves back and forth between the upper and lower surfaces of the film, when the resin tank moving mechanism moves in a certain direction (upward or downward), the light spot should appear twice in succession. The clarity change trends of the two light spots are basically the same. Combined with the moving direction of the resin tank moving mechanism, it can be determined which light spot corresponds to the projection area of ​​the upper surface of the film and which light spot corresponds to the projection area of ​​the lower surface of the film. Specifically, when the resin tank moving mechanism moves downward during the two appearances of the light spots, the projection area where the light spot that appears later is located is the lower surface of the film. When the resin tank moving mechanism moves upward during the two appearances of the light spots, the projection area where the light spot that appears first is located is the lower surface of the film.

[0085] The above-mentioned method of identifying the lower surface of the membrane is simple and convenient, and does not increase the hardware cost of the device.

[0086] In some embodiments, sub-step S1012, before accurately focusing the lower surface of the membrane according to the light spot corresponding to the lower surface of the membrane, may include: step S108.

[0087] Step S108: adjusting and determining that the light source is currently within an optimal energy value range.

[0088] At this time, sub-step S1012, precisely focusing the lower surface of the membrane according to the light spot corresponding to the lower surface of the membrane, may include: based on the light source currently being within the optimal energy value range, precisely focusing the lower surface of the membrane according to the light spot corresponding to the lower surface of the membrane.

[0089] Because the clarity and brightness of the light spot on the same platform's projection area, when located on the focal plane, vary under different light intensities, generally within a certain range, the higher the light intensity, the clearer and brighter the light spot in the projection area. Beyond a certain light intensity, the changes in clarity and brightness of the light spot in the projection area become less significant. Therefore, to achieve more precise focusing, the energy value of the light source should be adjusted before performing precise focusing. This should ensure that the light source is within the optimal energy range when projecting onto the film's lower surface. Within this optimal energy range, the light spot's clarity and brightness are essentially optimal, facilitating more precise focusing.

[0090] The resin tank movement mechanism's step length during initial focus is larger than that during fine focus. Since the camera performs real-time detection, there are potential issues with insufficient camera frame rate or slow data transmission leading to response delays. Therefore, during fine focus, the resin tank movement mechanism uses shorter step lengths, allowing for image acquisition and comparison at each step. Furthermore, between initial and fine focus, the light source can be adjusted to the appropriate intensity (i.e., within the optimal energy range), resulting in a more pronounced contrast and a more accurate focus during fine focus.

[0091] In some embodiments, sub-step S1012, precisely focusing the lower surface of the membrane according to the light spot corresponding to the lower surface of the membrane, may include: using a multi-point comparison climbing focusing method to precisely focus the lower surface of the membrane according to the light spot corresponding to the lower surface of the membrane.

[0092] The multi-point comparison climbing focus method can compare the clarity and brightness of the light spot at multiple positions, and can more accurately find the light spot with the best clarity and brightness. The position of the lower surface of the film corresponding to this light spot is closest to the focusing plane.

[0093] 7 , in some embodiments, step S102 , controlling the distance between the focusing plane and the molding surface of the printing platform to be within a preset distance range, may include: sub-step S1021 , sub-step S1022 , and sub-step S1023 .

[0094] Sub-step S1021: Determine a third position of the platform moving mechanism in the vertical direction when the molding surface of the printing platform is in the focus plane.

[0095] Sub-step S1022: controlling the platform moving mechanism to move downward in the vertical direction starting from the third position.

[0096] Sub-step S1023: When the downward movement distance of the platform moving mechanism is within the preset distance range, determining the second position of the platform moving mechanism in the vertical direction at this time.

[0097] In an embodiment of the present application, the distance between the focusing plane and the molding surface of the printing platform is controlled to be within a preset distance range. The method adopted is: since the position of the focusing plane is fixed, first determine the third position of the platform moving mechanism in the vertical direction when the molding surface of the printing platform is in the focusing plane, and then adjust the distance between the focusing plane and the molding surface of the printing platform, that is, control the platform moving mechanism to move downward in the vertical direction starting from the third position. When the distance moved downward by the platform moving mechanism is within the preset distance range, determine the second position of the platform moving mechanism in the vertical direction at this time; since the platform moving mechanism moves downward from the third position when the molding surface of the printing platform is in the focusing plane, when the platform moving mechanism is in the second position in the vertical direction, it indicates that the distance between the focusing plane and the molding surface of the printing platform is within the preset distance range.

[0098] This method is simple and convenient, and fully utilizes the existing hardware of the device. It no longer requires the device to be additionally equipped with hardware for measuring distance, thus saving the hardware cost of the device.

[0099] Among them, the above methods can also be used when focusing on the molding surface of the printing platform, such as adjusting the energy value of the light source, capturing image stream data through the camera, adjusting the energy value of the light source to the optimal value during spot indexing and precise focusing, etc.

[0100] In some embodiments, sub-step S1021, determining the third position of the platform moving mechanism in the vertical direction when the molding surface of the printing platform is in the focus plane, may include:

[0101] A. If there is a light spot in the projection area and the outline and clarity of the light spot meet preset requirements, adjust and determine that the light source is currently within the optimal energy value range, and accurately focus the molding surface of the printing platform based on the light spot in the projection area, and determine the third position of the platform moving mechanism in the vertical direction when the molding surface of the printing platform is in the focusing plane.

[0102] B. If there is no light spot in the projection area, the light source is adjusted to be within the maximum energy value range and the preset standard picture is projected again. If there is still no light spot in the projection area, a light spot search is performed by light spot indexing. When a light spot is found and the outline and clarity of the light spot meet the preset requirements, the light source is adjusted and determined to be currently within the optimal energy value range, and the molding surface of the printing platform is precisely focused according to the light spot in the projection area, and the third position of the platform moving mechanism in the vertical direction is determined when the molding surface of the printing platform is in the focusing plane.

[0103] C. When a light spot is found and the outline and clarity of the light spot do not meet the preset requirements, initial focus and precise focus are performed on the molding surface of the printing platform according to the light spot in the projection area, and the third position of the platform moving mechanism in the vertical direction is determined when the molding surface of the printing platform is in the focusing plane.

[0104] In some embodiments, within the upper and lower limit movement ranges of the platform moving mechanism, when it is determined that no light spot is searched in the entire projection area, the light spot search is exited and a prompt message is issued, wherein the prompt message is used to indicate that there may be a problem with the camera or optical machine.

[0105] The above method is described in detail below using a specific embodiment. This specific embodiment mainly focuses on the autofocus process, namely, automatic identification of the upper and lower surfaces of the film, automatic focusing of the lower surface of the film, and automatic focusing of the molding surface of the printing platform. This autofocus process combines the automatic identification of the upper and lower surfaces of the film, the automatic focusing of the lower surface of the film, and the automatic focusing of the molding surface of the printing platform. The specific description is as follows:

[0106] STEP 1 (initial judgment): The DLP light source projects a 100*100 pixel calibration image (see Figure 8) at the default energy value, and filters and analyzes the image (i.e., image stream data) fed back by the industrial camera; if it is determined that there is no light spot, enter S1; if it is determined that there is a light spot, enter S2.

[0107] S1: If there is no light spot, switch the DLP light source to the maximum energy value and expose again. If there is still no light spot, enter SETP2.

[0108] S2: If there is a light spot, and the outline and clarity of the light spot meet the predetermined range, go to STEP 5; otherwise, if there is a light spot, but the outline and clarity of the light spot do not meet the predetermined range, go to STEP 3.

[0109] STEP 2 (spot indexing): Using alternating forward and reverse step lengths A (i.e., the first step length) and doubling the speed (see Figure 9), the industrial camera retrieves the feedback image in real time and analyzes the changes in the camera image as the surface to be measured moves up and down. This process specifically includes:

[0110] S1: If a light spot is detected during the light spot indexing process:

[0111] 1) If the outline and clarity of the light spot meet the predetermined range, the Z axis (Z1 axis or Z2 axis) moves to the position where the clarity of the light spot is the highest according to the synchronous position information, and then enters STEP 5.

[0112] 2) If the spot profile and clarity do not meet the predetermined range, the Z axis moves to the position with the highest spot clarity according to the synchronization position information, and then enters STEP 3.

[0113] S2: If the light spot is not found within the vertical movement range of the Z axis, the light spot index is exited and an alarm pop-up window appears to indicate that there may be a problem with the camera or optical machine.

[0114] STEP 3 (Initial Focus): Using alternating forward and reverse steps of step length B (i.e., the second step, where step B is smaller than step length A), the camera moves at double the speed (see Figure 9). The industrial camera retrieves the feedback image in real time, detecting and analyzing the changes in the camera image during the up and down movement of the surface being measured (the build surface of the print platform, the upper surface of the film, or the lower surface of the film). If the clarity of the light spot in the image shows a clear trend (rising, peaking, and then falling), the Z axis moves to the position with the highest clarity based on the synchronized position information, and then proceeds to STEP 4.

[0115] STEP 4 (Calibration): To address possible interference factors in actual use (such as insufficient camera frame rate, response delay, etc.), a multi-point comparison climbing and aggregation method (see Figure 10) is used to calibrate the focus position. This will bring the projection area closer to the focus position, making subsequent precise focusing faster. After calibration, proceed to STEP 5.

[0116] STEP 5 (Light Intensity Adjustment): Adjust the energy value of the DLP light source to the optimal energy value for projection. This can prevent the camera image from being overexposed or underexposed, thereby improving the camera image contrast, and then proceed to STEP 6.

[0117] STEP 6 (Precise Focus): After the above steps, the plane to be measured is now near the focal point, and the DLP light source energy value has been adjusted to a reasonable range. Focus is now performed using a multi-point comparison and hill-climbing method (see Figure 10), with an initial step of 1 focal depth. When the index step is less than 1 / 8 of the focal depth, the current position is considered in focus.

[0118] The present application also provides another light-curing 3D printing device. It should be noted that the device in the embodiment of the present application can implement the printing method of the above-mentioned light-curing 3D printing device. For detailed description of the relevant content, please refer to the above-mentioned method section, which will not be repeated here.

[0119] The device includes: a film stretching assembly, a resin tank, a resin tank moving mechanism, a printing platform, a platform moving mechanism and a projection lens. The film stretching assembly is arranged on the resin tank. The resin tank can move in the vertical direction under the drive of the resin tank moving mechanism. The film stretching assembly moves following the resin tank. The printing platform can move in the vertical direction under the drive of the platform moving mechanism.

[0120] The device further includes: a processor and a memory, the memory is further used to store a computer program, and the processor is used to execute the computer program and implement the printing method of any of the above-mentioned light-curing 3D printing devices when executing the computer program.

[0121] The processor may be a microcontroller unit, a central processing unit, a digital signal processor, etc. The memory may be a Flash chip, a read-only memory, a magnetic disk, an optical disk, a USB flash drive, or a mobile hard disk, etc.

[0122] This application also provides a computer-readable storage medium storing a computer program. When executed by a processor, the computer program causes the processor to implement any of the above-described printing methods for a photocurable 3D printing device. For detailed descriptions of the relevant content, please refer to the above-described printing methods for photocurable 3D printing devices, and will not be repeated here.

[0123] The computer-readable storage medium may be an internal storage unit of the apparatus, such as a hard disk or memory. The computer-readable storage medium may also be an external storage device, such as a plug-in hard disk, smart memory card, secure digital card, flash memory card, etc.

[0124] It should be understood that the terms used in the present specification are only used to describe specific embodiments and are not intended to limit the present application.

[0125] It will also be understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0126] The above descriptions are merely specific embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and such modifications or substitutions should be included within the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A printing method of a light-curing 3D printing device, the device comprising: A film stretching assembly, a resin tank, a resin tank moving mechanism, a printing platform, a platform moving mechanism, and a projection lens, wherein the film stretching assembly is arranged on the resin tank, the resin tank can move in a vertical direction driven by the resin tank moving mechanism, the film stretching assembly moves following the movement of the resin tank, and the printing platform can move in the vertical direction driven by the platform moving mechanism, and the method comprises: Determining, by means of automatic focusing, that the resin tank moving mechanism is in a first position in the vertical direction when the lower surface of the film of the stretch film assembly is in a focusing plane of the projection lens; Controlling the distance between the focus plane and the molding surface of the printing platform to be within a preset distance range, and determining a second position of the platform moving mechanism in the vertical direction at this time; and Printing is performed according to the first position and the second position.

2. The method according to claim 1, wherein: The method of determining the first position of the resin tank moving mechanism in the vertical direction when the lower surface of the film of the stretch film assembly is in the focal plane of the projection lens by means of automatic focusing comprises: Initially focusing the upper and lower surfaces of the film of the film stretching assembly according to the light spot in the projection area, and during the initial focusing process, determining the light spot corresponding to the lower surface of the film according to the change trend of the clarity of the light spot twice before and after and the moving direction of the resin tank moving mechanism; The lower surface of the film is precisely focused according to the light spot corresponding to the lower surface of the film, and the first position of the resin tank moving mechanism in the vertical direction is determined when the lower surface of the film is in the focusing plane.

3. The method according to claim 2, wherein: Before initially focusing the upper and lower surfaces of the film of the stretch film assembly according to the light spot in the projection area, the method includes: Control the light source to project a preset standard image with a preset default energy value; When it is determined that there is no light spot in the projection area, controlling the light source to project the preset standard image again with a preset maximum energy value; When it is determined again that there is no light spot in the projection area, a light spot search is performed by means of a light spot index.

4. The method according to claim 3, wherein: The light spot search is performed by means of light spot indexing, including: Control the resin tank moving mechanism to adopt the first step length doubling rapid movement in alternating forward and reverse directions; During the doubly rapid movement, it is determined whether there is a light spot in the projection area according to the image stream data of the projection area by the camera.

5. The method according to claim 4, wherein: The method further comprises: Within the upper and lower limit moving ranges of the resin tank moving mechanism, when it is determined that there is no light spot in the entire projection area, the light spot search is exited and a prompt message is issued, wherein the prompt message is used to indicate that there may be a problem with the camera or optical machine.

6. The method according to claim 2, wherein: The initial focusing of the upper and lower surfaces of the film of the film stretching assembly according to the light spot of the projection area includes: Control the resin tank moving mechanism to adopt a second step length doubling low speed movement in a forward and reverse alternating manner; During the doubled low-speed movement, when the change trends of the clarity of the light spot twice before and after are that the clarity gradually increases, the clarity is the highest, and the clarity gradually decreases, the moving direction of the resin tank moving mechanism is determined; When the resin tank moving mechanism moves downward during the process of the light spots appearing twice, the projection area where the light spot that appears later is located is determined to be the lower surface of the film. When the resin tank moving mechanism moves upward during the process of the light spots that appear twice, the projection area where the light spot that appears earlier is located is determined to be the lower surface of the film.

7. The method according to claim 2, wherein: Before the accurate focusing of the lower surface of the film according to the light spot corresponding to the lower surface of the film, the method includes: Adjust and determine that the light source is currently within the optimal energy value range; The step of accurately focusing the lower surface of the film according to the light spot corresponding to the lower surface of the film comprises: Based on the fact that the light source is currently within the optimal energy value range, the lower surface of the film is precisely focused according to the light spot corresponding to the lower surface of the film.

8. The method according to claim 1, wherein: The controlling the distance between the focus plane and the molding surface of the printing platform to be within a preset distance range comprises: Determining a third position of the platform moving mechanism in the vertical direction when the molding surface of the printing platform is in the focusing plane; Controlling the platform moving mechanism to move downward in the vertical direction starting from the third position; When the downward movement distance of the platform moving mechanism is within the preset distance range, the second position of the platform moving mechanism in the vertical direction at this time is determined.

9. The method according to claim 8, wherein: The determining that the molding surface of the printing platform is in the third position of the platform moving mechanism in the vertical direction when the molding surface of the printing platform is in the focusing plane includes: If there is a light spot in the projection area, and the outline and clarity of the light spot meet the preset requirements, then adjust and determine the light source. The projection area is within the optimal energy value range, and the molding surface of the printing platform is precisely focused according to the light spot in the projection area, and the third position of the platform moving mechanism in the vertical direction is determined when the molding surface of the printing platform is in the focusing plane; If there is no light spot in the projection area, the light source is adjusted to be within the maximum energy value range and the preset standard picture is projected again. If there is still no light spot in the projection area, a light spot search is performed by means of a light spot index. When a light spot is found and the contour and clarity of the light spot meet the preset requirements, the light source is adjusted and determined to be currently within the optimal energy value range, and the molding surface of the printing platform is precisely focused according to the light spot in the projection area, and the third position of the platform moving mechanism in the vertical direction is determined when the molding surface of the printing platform is in the focusing plane. When a light spot is searched and the contour and clarity of the light spot do not meet the preset requirements, initial focusing and precise focusing are performed on the molding surface of the printing platform according to the light spot in the projection area, and the third position of the platform moving mechanism in the vertical direction is determined when the molding surface of the printing platform is in the focusing plane.

10. A light-curing 3D printing device, comprising: A film stretching assembly, a resin tank, a resin tank moving mechanism, a printing platform, a platform moving mechanism and a projection lens, wherein the film stretching assembly is arranged on the resin tank, the resin tank can move in the vertical direction driven by the resin tank moving mechanism, the film stretching assembly moves following the resin tank, and the printing platform can move in the vertical direction driven by the platform moving mechanism, wherein the device also includes: a processor and a memory, the memory is also used to store a computer program, the processor is used to execute the computer program and implement the printing method of the light-curing 3D printing device as claimed in claim 1 when executing the computer program.

11. A computer-readable storage medium, wherein: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the processor implements the printing method of the light-curing 3D printing device according to claim 1.

12. A printing method of a light-curing 3D printing device, the device comprising: A film stretching assembly, a resin tank, a resin tank moving mechanism, a printing platform, a platform moving mechanism, and a projection lens, wherein the film stretching assembly is arranged on the resin tank, the resin tank can move in a vertical direction driven by the resin tank moving mechanism, the film stretching assembly moves following the movement of the resin tank, and the printing platform can move in the vertical direction driven by the platform moving mechanism, and the method comprises: Determining, by means of automatic focusing, that the resin tank moving mechanism is in a first position in the vertical direction when the lower surface of the film of the stretch film assembly is in a focusing plane of the projection lens; Control the distance between the focus plane and the molding surface of the printing platform within a preset distance range, and determine the The platform moving mechanism is in a second position in the vertical direction; Printing according to the first position and the second position; Wherein, the method of determining the first position of the resin tank moving mechanism in the vertical direction when the lower surface of the film of the film stretching assembly is in the focal plane of the projection lens by means of automatic focusing includes: Initially focusing the upper and lower surfaces of the film of the film stretching assembly according to the light spot in the projection area, and during the initial focusing process, determining the light spot corresponding to the lower surface of the film according to the change trend of the clarity of the light spot twice before and after and the moving direction of the resin tank moving mechanism; Precisely focusing the lower surface of the film according to the light spot corresponding to the lower surface of the film, and determining a first position of the resin tank moving mechanism in the vertical direction when the lower surface of the film is in the focusing plane; Wherein, controlling the distance between the focus plane and the molding surface of the printing platform to be within a preset distance range includes: Determining a third position of the platform moving mechanism in the vertical direction when the molding surface of the printing platform is in the focusing plane; Controlling the platform moving mechanism to move downward in the vertical direction starting from the third position; When the downward movement distance of the platform moving mechanism is within the preset distance range, the second position of the platform moving mechanism in the vertical direction at this time is determined.

13. The method according to claim 12, wherein: Before initially focusing the upper and lower surfaces of the film of the stretch film assembly according to the light spot in the projection area, the method includes: Control the light source to project a preset standard image with a preset default energy value; When it is determined that there is no light spot in the projection area, controlling the light source to project the preset standard image again with a preset maximum energy value; When it is determined again that there is no light spot in the projection area, performing a light spot search by means of a light spot index; The light spot search is performed by light spot indexing, including: Control the resin tank moving mechanism to adopt the first step length doubling rapid movement in alternating forward and reverse directions; During the doubly rapid movement, it is determined whether there is a light spot in the projection area according to the image stream data of the projection area by the camera.

14. The method according to claim 12, wherein: The initial focusing of the upper and lower surfaces of the film of the film stretching assembly according to the light spot of the projection area includes: Control the resin tank moving mechanism to adopt a second step length doubling low speed movement in a forward and reverse alternating manner; During the doubled low-speed movement, when the change trends of the clarity of the light spot twice before and after are that the clarity gradually increases, the clarity is the highest, and the clarity gradually decreases, the moving direction of the resin tank moving mechanism is determined; When the resin tank moving mechanism moves downward during the process of the light spots appearing twice, the projection area where the light spot that appears later is located is determined to be the lower surface of the film. When the resin tank moving mechanism moves upward during the process of the light spots that appear twice, the projection area where the light spot that appears earlier is located is determined to be the lower surface of the film.

15. The method according to claim 12, wherein: Before the accurate focusing of the lower surface of the film according to the light spot corresponding to the lower surface of the film, the method includes: Adjust and determine that the light source is currently within the optimal energy value range; The step of accurately focusing the lower surface of the film according to the light spot corresponding to the lower surface of the film comprises: Based on the fact that the light source is currently within the optimal energy value range, the lower surface of the film is precisely focused according to the light spot corresponding to the lower surface of the film.

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