CN112265262B

CN112265262B - Photo-curing type 3D printing device

Info

Publication number: CN112265262B
Application number: CN201910610274.5A
Authority: CN
Inventors: 侯锋
Original assignee: Prismlab Information Technology Ltd; PRISMLAB CHINA Ltd
Current assignee: Prismlab Information Technology Ltd; Shanghai Pulisheng 3d Technology Co ltd
Priority date: 2019-07-08
Filing date: 2019-07-08
Publication date: 2023-08-15
Anticipated expiration: 2039-07-08
Also published as: WO2021004064A1; CN112265262A

Abstract

The application provides a photo-curing type 3D printing device, comprising: the shell is internally provided with liquid photosensitive resin for forming a workpiece, wherein the inside of the shell is in a low-pressure environment; the lifting platform is arranged in the shell and is used for bearing the formed workpiece; the driving mechanism drives the lifting platform to do lifting motion; the optical system is positioned below the shell and can radiate a beam pattern, so that a layer of photosensitive resin at the inner bottom of the shell is controllably solidified.

Description

Photo-curing type 3D printing device

Technical Field

The present application relates to a three-dimensional (3D) printing apparatus, and more particularly, to a photo-curing type 3D printing apparatus.

Background

The 3D printing technology is to laminate a computer three-dimensional design model by software, stack and bond special materials such as metal powder, ceramic powder, plastic, cell tissues and the like layer by layer in a laser beam, a hot melting nozzle and the like mode, and finally stack and mold the special materials to manufacture a solid product. Unlike traditional manufacturing, which produces final product by shaping, cutting and other modes of raw materials in mechanical processing modes such as mold, turning and milling, 3D printing changes three-dimensional entity into a plurality of two-dimensional planes, and the manufacturing complexity is greatly reduced by processing materials and producing the materials layer by layer. The digital manufacturing mode can directly generate parts with any shape from the computer graphic data without complex process, huge machine tool and numerous manpower, so that the production and manufacturing can be extended to a wider production crowd range.

At present, the forming mode of the 3D printing technology is continuously evolving, and the used materials are also various. Among the various molding methods, the photo-curing method is a more mature method. The photocuring method is to utilize the principle that a photosensitive material (usually photosensitive resin) is cured after being irradiated by ultraviolet laser to carry out material accumulation molding, and has the characteristics of high molding precision, good surface smoothness, high material utilization rate and the like.

Fig. 1 is a schematic diagram of a basic structure of a photo-curing type 3D printing device. The 3D printing apparatus 100 includes a liquid container 110 for containing a photosensitive resin, an optical system 120 for curing the photosensitive resin, and a lifting platform 130 for connecting a molded workpiece. The optical system 120 is located below the liquid container 110, and irradiates a light beam pattern to cure a layer of photosensitive resin on the bottom surface of the liquid container 110, and the cured photosensitive resin is adhered to the bottom surface of the lifting platform 130. After each exposure of the optical system 120 to the beam pattern causes one layer of photosensitive resin to cure, the lift platform 130 is raised slightly to lift the cured layer of photosensitive resin and allow the photosensitive resin, which is still in a liquid state, to flow between the bottom contact layer of the liquid container 110 and the cured resin to wait for the next exposure. And (3) circulating in this way, printing layer by layer from the topmost layer to the bottommost layer of the three-dimensional model, and accumulating to obtain the formed three-dimensional workpiece.

During the lifting of the lifting platform 130, there is no air gap between the cured resin and the contact layer of the bottom surface of the liquid container 110, and the cured resin is pressed against the contact layer by atmospheric pressure. Under the dual actions of the resistance formed by the atmospheric pressure and the inherent adhesion force of the photo-curing resin and the bottom surface of the liquid container, the lifting platform 130 is difficult to lift the cured resin together when lifted, and the partially cured resin remains on the bottom surface of the liquid container 110, so that the formed workpiece is defective. The inherent adhesion force between the photo-setting resin and the bottom surface of the liquid container 110 can be relieved by adding a non-adhesive layer to the bottom surface of the liquid container 110, but when the exposure area is large, the atmospheric pressure will be a main cause of difficulty in separating the contact layer and the cured resin on the bottom surface of the liquid container 110, especially when the micro-nano scale is entered, the requirement on the contact layer is extremely high, hard materials such as glass must be used as the contact layer, and the pressure caused by the atmospheric pressure cannot be released by peeling, which is more obvious.

Disclosure of Invention

The application aims to solve the technical problem of providing a photocuring type 3D printing device so as to reduce the lifting pressure of a lifting platform and ensure the integrity of a formed workpiece.

In order to solve the above technical problems, the present application provides a light-curable 3D printing device, comprising: the shell is internally provided with liquid photosensitive resin for forming a workpiece, wherein the inside of the shell is in a low-pressure environment; the lifting platform is arranged in the shell and is used for bearing the formed workpiece; the driving mechanism drives the lifting platform to do lifting motion; the optical system is positioned below the shell and can radiate a beam pattern, so that a layer of photosensitive resin at the inner bottom of the shell is controllably solidified.

In an embodiment of the application, a bottom of the housing has a contact layer, and the contact layer is a non-adhesive material.

In an embodiment of the application, the driving mechanism is a stepping or servo motor, and the stepping or servo motor is connected to the lifting platform through a screw rod.

In one embodiment of the present application, the driving mechanism is located above the liquid photosensitive resin in the housing, and the housing is provided with a vacuum hole, and the vacuum hole is connected to a vacuum pump, and the vacuum pump is used for pumping the interior of the housing to a low pressure or vacuum below atmospheric pressure.

In one embodiment of the application, the vacuum port is further connected to a vacuum gauge for measuring the vacuum level inside the housing.

In one embodiment of the present application, the printing apparatus further comprises a vent hole, which is opened to release the low pressure environment inside the housing after the printing task is completed.

In an embodiment of the application, the housing comprises an openable panel or cover plate, and the panel or cover plate is in sealing connection with the housing main body through a sealing rubber ring.

In one embodiment of the application, the driving mechanism is located outside the housing, the housing is filled with liquid photosensitive resin, and the housing is further connected to a piston, and the piston is in contact with the liquid photosensitive resin.

In one embodiment of the application, the piston is connected to a driver which drives the piston in a reciprocating motion.

In one embodiment of the present application, the apparatus further comprises a storage tank, wherein the storage tank stores liquid photosensitive resin, and the stored liquid photosensitive resin can be injected into the shell.

Compared with the prior art, the application has the following advantages: the application keeps the inside of the shell for containing the liquid photosensitive resin in a low-pressure environment, reduces the atmospheric pressure born by the printing piece, and enables the lifting platform to drive the formed workpiece to easily leave the bottom surface of the liquid containing tank, thereby protecting the success rate and the integrity of the formed workpiece and improving the quality of the formed workpiece.

Drawings

In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below, wherein:

fig. 1 is a schematic view of a basic structure of a photo-curing type 3D printing apparatus;

fig. 2 is a front view of a schematic structural diagram of a photo-curing type 3D printing device according to an embodiment of the present application;

fig. 3 is a perspective view of a schematic structural diagram of the photo-curing type 3D printing device shown in fig. 2;

fig. 4 is a bottom view of a schematic structural diagram of the photo-curing type 3D printing device shown in fig. 2;

fig. 5 is a top view of a schematic perspective view of the photo-curing type 3D printing device shown in fig. 2;

FIG. 6 is a flowchart of an exemplary process by which a 3D printing device prints according to one embodiment of the application;

FIG. 7 is a flow chart of an exemplary process included in step 630 of FIG. 6;

fig. 8 is a perspective view showing a schematic structural diagram of a photo-curing type 3D printing apparatus according to another embodiment of the present application;

fig. 9 is a flowchart of an exemplary process of printing by a 3D printing device according to an embodiment of the present application.

Detailed Description

In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, but the present application may be practiced in other ways than as described herein, and therefore the present application is not limited to the specific embodiments disclosed below.

As used in the specification and in the claims, the terms "a," "an," "the," and/or "the" are not specific to a singular, but may include a plurality, unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" merely indicate that the steps and elements are explicitly identified, and they do not constitute an exclusive list, as other steps or elements may be included in a method or apparatus.

A flowchart is used in the present application to describe the operations performed in accordance with embodiments of the present application. It should be appreciated that the preceding or following operations are not necessarily performed in order precisely. Rather, the various steps may be processed in reverse order or simultaneously. At the same time, other operations are added to or removed from these processes.

The light-curing type 3D printing device comprises a shell, a lifting platform, a driving mechanism and an optical system. The shell is internally provided with liquid photosensitive resin for forming a workpiece, and the shell is internally provided with a low-pressure environment; the lifting platform is arranged in the shell and is used for bearing the formed workpiece; the driving mechanism can drive the lifting platform to do lifting motion; the optical system is positioned below the shell and can radiate a light beam pattern, so that a layer of photosensitive resin at the inner bottom of the shell is controllably cured.

In the light-curable 3D printing device according to the embodiment of the present application, the bottom surface of the housing is typically made of a light-transmitting material, such as glass. The bottom surface of the housing may be entirely or partially composed of a light-transmitting material. An optical system located below the case irradiates a beam pattern toward the bottom surface of the case, and the beam passes through the light-transmitting material to be irradiated onto a photosensitive resin located on the inner bottom surface of the case, which is cured in accordance with the irradiated beam pattern. The curing thickness (layer thickness) of the liquid photosensitive resin is determined by the distance between the molded work and the contact layer of the bottom surface of the liquid container 110.

In some embodiments, a contact layer is provided on the lower surface of the inside of the case, which is in contact with the liquid photosensitive resin, and the contact layer is a release film made of a non-adhesive material. The contact layer can prevent the solidified resin from adhering to the lower surface of the inside of the shell, and the solidified resin can be conveniently peeled off from the lower surface of the inside of the shell under the action of external force. In other embodiments, such as high precision micro-nano printing, due to high precision requirements, a solution is often employed in which the non-stick layer is plated directly onto the glass. Because the inside of the shell is in a low-pressure environment, after printing of part or all of the three-dimensional model is completed, the driving mechanism in the 3D printing device can not receive pressure from atmospheric pressure acting on a printing workpiece in the process of driving the lifting platform to do lifting motion. Therefore, the lifting platform can conveniently drive the solidified resin to rise or fall, so that the integrity of the formed workpiece is prevented from being damaged.

Fig. 2 is a front view of a schematic structural diagram of a photo-curing type 3D printing device according to an embodiment of the present application. Referring to fig. 2, in this embodiment, the housing 210 of the photo-curing type 3D printing apparatus is a closed box. The optical system 220 is located below the housing 210 with a distance from the housing 210. It is understood that the shape of the case 210 may be regular or irregular square, rectangular parallelepiped, etc., and the schematic diagram of fig. 2 is not intended to limit the shape of the case 210 in the photo-curing type 3D printing device of the present application. The housing 210 may be made of a light-transmitting material or a light-impermeable material except for a portion of the bottom thereof for transmitting light. The use of transparent material is beneficial in that it facilitates viewing the operation of the interior of the housing 210. The use of an opaque material has the advantage that stray light may be prevented from entering the housing 210. Preferably, the housing 210 is constructed of a combination of transparent and opaque materials.

From the front view shown in fig. 2, there is a panel 211 with a handle on the front surface of the housing 210, and the panel 211 can be opened and closed. At the top of the housing 210 is a cover plate 212 that can be opened and closed. In some embodiments, both the panel 211 and the cover 212 are sealingly connected by a sealing gasket. In some embodiments, the cover plate of the housing 210 may be fixed to the housing 210. Whatever the manner in which the panel 211 and the cover 212 are disposed on the housing 210, the tightness of the interior of the housing 210 is ensured when the panel 211 and/or the cover 212 are closed.

Referring to fig. 2, in this embodiment, a vacuum hole 213 is provided in the housing 210 at one side of the panel 211. In other embodiments, the vacuum holes 213 may be located elsewhere on the housing 210. The vacuum hole 213 is connected to a vacuum pump (not shown) for pumping the inside of the housing 210 to a low pressure state lower than the atmospheric pressure, thereby making the inside of the housing 210 in a low pressure environment. Ideally, the vacuum pump can evacuate the interior of the housing 210.

In some embodiments, vacuum holes 213 are also connected to a vacuum gauge (not shown) that is used to measure the vacuum level inside housing 210 and may be used to indicate and control the operation of the vacuum pump.

Referring to fig. 2, in this embodiment, a vent hole 214 is provided in the housing 210 at one side of the panel 211. In other embodiments, the vent 214 may be located elsewhere on the housing 210. After printing of the three-dimensional model is completed within the housing 210, the vent 214 may be opened to relieve the low air pressure environment inside the housing 210.

Fig. 3 is a perspective view of a schematic structural diagram of the photo-curing type 3D printing device shown in fig. 2. Referring to fig. 3, a liquid tank 215 for containing liquid photosensitive resin, a lifting platform 230 and a driving mechanism 240 are included in the housing 210 of the present embodiment. The driving mechanism 240 is connected to the lifting platform 230 through a screw 241, and drives the lifting platform 230 to reciprocate along a vertical direction through the screw 241.

Fig. 4 is a bottom view of a schematic structural diagram of the photo-curing type 3D printing device shown in fig. 2. Referring to fig. 4, a light transmitting portion 217 is provided at the bottom of the exterior of the housing 210 of the present embodiment. The light emitted from the optical system 220 may pass through the light-transmitting portion 217, so that a layer of liquid photosensitive resin located inside the case 210 is cured according to the light pattern. It will be appreciated that the illustration in fig. 4 is merely schematic and is not intended to limit the shape and size of the light-transmitting portion 217. In a preferred embodiment, the transparent portion 217 is rectangular, and the bottom of the housing 210 is made of opaque material surrounding the transparent portion 217, so that stray light is prevented from entering the bottom of the housing 210.

Fig. 5 is a plan view schematically showing the structure of the photo-curing type 3D printing apparatus shown in fig. 2. Referring to fig. 5, in this embodiment, the bottom of the housing 210 has a liquid tank 215 for containing liquid photosensitive resin. Above the liquid container 215 is a scraper 250. The driving mechanism 240 is located inside the housing 210 above the liquid photosensitive resin, that is, the driving mechanism 240 is located above the liquid container 215 and the squeegee 250. The lift platform 230 is also located inside the housing 210 and is coupled to a drive mechanism 240.

Referring to fig. 2-5, in this embodiment, the housing 210 has a rectangular parallelepiped structure. Since the driving mechanism 240 is disposed at the back plate opposite to the front plate 211 of the housing 210 and is higher, the portion of the cover plate 212 of the housing 210 close to the front plate 211 is a lower flat plate, the portion close to the back plate is a higher flat plate, and the whole cover plate 212 is in a step shape with lower front and higher rear. The shape of the cover plate 212 of the 3D printing device of the present application is not limited as shown in fig. 2-5.

Fig. 6 is a flowchart of an exemplary process of printing by a 3D printing device according to an embodiment of the present application. The 3D printing apparatus of the embodiment shown in fig. 2 to 5 can perform printing of a three-dimensional model according to the steps of the flow shown in fig. 6. Referring to fig. 6, the printing process includes the steps of:

in step 610, liquid photosensitive resin required for printing is injected into the liquid container in the housing, and the panel and/or cover plate of the housing are closed.

In this step, a liquid photosensitive resin sufficient to print a desired three-dimensional model is injected into the liquid container 215 in the housing 210, and the panel 211 and/or the cover 212 of the housing 210 are closed, so that the interior of the housing 210 is in a closed state.

Step 620, vacuumize the interior of the housing through the vacuum holes in the housing using a vacuum pump.

In this step, the air pressure inside the housing 210 is simultaneously detected by the vacuum gauge connected to the vacuum hole 213, so that the air pressure inside the housing 210 is low, preferably, the air pressure should be between 0 and 0.5 atm during the three-dimensional printing process.

Step 630, begin printing the three-dimensional model layer by layer.

Fig. 7 is a flow chart of an exemplary process included in step 630 of fig. 6. Referring to fig. 7, step 630 may include the following steps:

at step 631, at the beginning of printing, the driving mechanism 240 drives the lifting platform 230 to make the distance between the lifting platform 230 and the bottom surface of the liquid container 215 equal to the thickness of a layer of three-dimensional model.

In step 632, the optical system 220 irradiates a light beam to the lower side of the case 210 according to the slice image of the topmost layer of the three-dimensional model to be printed, and cures the first layer of photosensitive resin to form a first layer printing surface.

In step 633, in some embodiments, after a layer of print surface is formed, the driving mechanism 240 drives the lifting platform 230 to lift upwards, and the lifting platform 230 drives the cured resin to lift a distance together and stop. The squeegee 250 in the 3D printing device starts to operate, moves from one end of the liquid container 215 to the other end, and cleans the contact layer for printing of the next printing surface. After the squeegee 250 is operated, the driving mechanism 240 drives the elevating platform 230 to descend to a position where the distance between the cured resin on the elevating platform 230 and the bottom surface of the liquid container 215 is equal to the thickness of one printing surface. So that the next layer of cured resin can be joined to the previous layer of cured resin at the next photo-printing. The use of the squeegee 250 allows the contact layer to be kept clean, and the quality of the molded workpiece to be improved.

In other embodiments, assuming the contact layer is clean, the squeegee 250 may not be required, and after a layer of print surface is formed, the drive mechanism 240 may drive the lift platform 230 to rise a distance greater than the thickness of the print surface layer and then to drop a distance from the surface equal to the thickness of a layer of three-dimensional model print surface.

In step 634, the optical system 220 irradiates a light beam to the lower side of the case 210 according to the pattern of the next slice image in the three-dimensional model, so that a layer of photosensitive resin at the bottom of the case 210 is cured.

Repeating the steps 631 to 634, printing the three-dimensional model to be printed layer by layer until the molded workpiece is finally obtained.

With continued reference to FIG. 6, at step 640, after printing of the entire three-dimensional model is completed, the vent holes in the housing are opened.

This step allows air to enter the airtight housing 210, thereby releasing the low air pressure environment inside the housing 210. And the subsequent molded workpiece is also convenient to take out.

In some embodiments, the drive mechanism 240 may be a stepper motor or a servo motor that is coupled to the lift platform 230 by a lead screw 241. The lifting platform 230 can slide up and down along the screw 241 under the driving of a stepping motor or a servo motor.

The embodiment of the application provides a photocuring type 3D printing device, which ensures that the inside of a shell for containing liquid photosensitive resin is kept in a low-pressure environment, eliminates larger atmospheric pressure borne by the liquid photosensitive resin and a lifting platform, and ensures that the lifting platform can drive a formed workpiece to easily leave the bottom surface of a liquid containing tank, thereby protecting the integrity of the formed workpiece and improving the quality of the formed workpiece.

Fig. 8 is a perspective view of a schematic structural diagram of a photo-curing type 3D printing device according to another embodiment of the present application. This has the advantage that after the separation of the elevating platform 230 from the bottom surface inside the housing 210, the liquid resin can be pressed into the gap between the elevating platform 230 and the bottom surface inside the housing 210. Referring to fig. 8, in this embodiment, a housing 210 of the 3D printing apparatus is a closed container, the housing 210 is filled with a liquid photosensitive resin, and the interior of the housing 210 is still in a low-pressure environment. The housing 210 is connected to a piston 260. As shown in fig. 8, there is a boss 216 near the bottom of the housing 210, the boss 216 being integral with the housing 210, and the piston 260 being located within the boss 216. The plug portion 261 of the plunger 260 is in contact with the liquid photosensitive resin in the housing 210. The plug 261 is matched with the boss 216 of the case 210 so that the liquid photosensitive resin in the case 210 does not flow from one side of the plug 261 to the other side. The stem 262 may be coupled to a driver (not shown) that drives the stem 262 to reciprocate the stem 261 together within the boss 216.

The schematic view shown in fig. 8 does not limit the position of the boss 216. In a preferred embodiment, as shown in FIG. 8, the boss 216 is positioned near the bottom of the housing 210. When the driver drives the piston 260 to move away from the housing 210, the negative pressure in the housing 210 is enhanced, so that the workpiece and the contact layer are separated conveniently; when the driver drives the piston 260 to move toward the housing 210, the positive pressure in the housing 210 is increased, so that the liquid photosensitive resin flows into the gap between the workpiece and the contact layer formed after the lifting platform 230 is lifted, which is beneficial to accelerating printing.

Referring to fig. 8, in this embodiment, the 3D printing apparatus further includes a driving mechanism 240 located outside the housing 210. The driving mechanism 240 is connected to the elevating platform 230 located inside the housing 210 through a screw 241. Also included outside the housing 210 is a storage tank 270, wherein the storage tank 270 stores liquid photosensitive resin. The storage tank 270 is communicated with the housing 210, and when printing is required, the stored liquid photosensitive resin can be injected into the housing 210, and after printing is finished, the residual liquid photosensitive resin is pumped back to the storage tank 270, so that the printed piece can be conveniently taken out. Of course, whether the driving mechanism 240 or the storage tank 270 is connected to the housing 210, the air tightness of the connection portion is ensured, so that the housing 210 maintains a set low air pressure environment state during printing by the 3D printing device.

In some embodiments, both the drive mechanism 240 and the driver may be stepper motors or servo motors.

Referring to fig. 8, in this embodiment, the 3D printing apparatus further includes a liquid container 215. Since the liquid photosensitive resin fills the inside of the case 210, the liquid container 215 corresponds to the entire space inside the case 210.

In this embodiment, the housing 210 has a rectangular parallelepiped structure from the perspective shown in fig. 8. The bottom surface of the housing 210, i.e., the surface to be illuminated by the optical system 220, is desirably formed entirely or partially of a transparent material, such as glass. A contact layer is provided on a lower surface of the inside of the case 210, which is in contact with the liquid photosensitive resin. The remainder of the housing 210 may be formed of a transparent material or an opaque material. The use of transparent material is beneficial in that it facilitates viewing the operation of the interior of the housing 210. The use of an opaque material has the advantage that stray light may be prevented from entering the housing 210. Preferably, the housing 210 is constructed of a combination of transparent and opaque materials.

The illustration of fig. 8 is not intended to limit the shape and size of the housing 210. In other embodiments, the housing 210 may be other shapes that achieve the objects of the present application.

Fig. 9 is a flowchart of an exemplary process of printing by a 3D printing device according to an embodiment of the present application. The 3D printing apparatus of the embodiment shown in fig. 8 can perform printing of a three-dimensional model according to the steps of the flow shown in fig. 9. Referring to fig. 9, the printing process includes the steps of:

at step 910, the housing 210 is filled with a liquid photosensitive resin.

Referring to fig. 8, the tank 270 and the housing 210 are connected by a pipe, which is located at the lower portions of the tank 270 and the housing 210. There is a bi-directional pump and valve assembly 271 in the line between the tank 270 and the housing 210. At the top end of the housing 210 is a bleed valve 272.

In this step 910, the purge valve 272 may be opened first, followed by the bi-directional pump and valve assembly 271; then, the liquid photosensitive resin in the storage tank 270 is injected into the shell 210, or the liquid in the storage tank 270 can be pressed into the shell 210 by injecting air pressure into the top of the storage tank 270; after the casing 210 is completely filled with the liquid photosensitive resin, the purge valve 272 is closed; finally, the bi-directional pump and valve assembly 271 is turned off.

Step 920, printing is started. At the beginning of printing, the driving mechanism 240 drives the lifting platform 230 so that the distance between the lifting platform 230 and the bottom surface of the liquid container 215 is equal to the thickness of a layer of three-dimensional model. The driver drives the plug 261 of the piston 260 to move toward the housing 210, so that positive pressure is generated in the housing 210, and the gap between the lifting platform 230 and the bottom surface of the liquid container 215 is ensured to be filled with resin material.

In step 930, the optical system 220 irradiates a light beam to the lower side of the case 210 according to the slice image of the topmost layer of the three-dimensional model to be printed, and cures the first layer of photosensitive resin to form a first layer printing surface.

In step 940, the driver drives the plug 261 of the piston 260 to move away from the housing 210, so that a negative pressure is generated in the housing 210. In this step, the pressure in the housing 210 may be measured by a pressure sensor (not shown), and when the pressure value reaches a set requirement (e.g., 0 to 0.5 atm), the movement of the plug 261 is stopped. The present application does not limit the location of the pressure sensor.

In step 950, the driving mechanism 240 drives the lifting platform 230 to lift to a proper position, so that the distance between the cured resin on the lifting platform 230 and the bottom surface of the liquid container 215 is suitable for the inflow of the liquid photosensitive resin.

In step 960, the driver drives the plug 261 of the piston 260 to move in a direction approaching the housing 210, so that positive pressure is generated in the housing 210. In this step, the pressure inside the housing 210 may be measured by a pressure sensor (not shown), and when the pressure value reaches a set requirement (for example, 1-2 atmospheres), the movement of the plug 261 is stopped.

In step 970, the driving mechanism 240 drives the lifting platform 230 to descend, so that the distance between the cured resin on the lifting platform 230 and the bottom surface of the liquid container 215 is equal to the thickness of one layer of printing surface.

In step 980, the optical system 220 irradiates a light beam to the lower side of the case 210 according to the pattern of the next slice image in the three-dimensional model, so that a layer of photosensitive resin at the bottom of the case 210 is cured. And also allows the next layer of cured resin to be joined to the previous layer of cured resin. Repeating the steps 940 to 980, and printing the three-dimensional model to be printed layer by layer until the molded workpiece is finally obtained.

At step 990, after printing is completed, the purge valve 272 and the bi-directional pump and valve assembly 271 are opened, the photosensitive resin material in the housing 210 is transferred back to the tank 270, and the photosensitive resin material is all transferred back to the tank 270, and the bi-directional pump and valve assembly 271 is closed.

Since the photosensitive resin material is cured with a certain shrinkage, the equilibrium position of the plug 261 in the boss 216 gradually moves toward the housing 210, and thus it is necessary to ensure a sufficient length of the boss 216 to allow the pressure in the housing 210 to reach the positive and negative air pressures required by the setting.

The embodiment of the application provides a photocuring type 3D printing device, which enables the inside of a shell for containing liquid photosensitive resin to be kept in a low-pressure environment, eliminates the atmospheric pressure borne by the liquid photosensitive resin and a lifting platform according to requirements, and enables the lifting platform to drive a formed workpiece to easily leave the bottom surface of a liquid containing tank, thereby protecting the integrity of the formed workpiece and improving the quality of the formed workpiece.

The application uses specific words to describe embodiments of the application. Reference to "one embodiment," "an embodiment," and/or "some embodiments" means that a particular feature, structure, or characteristic is associated with at least one embodiment of the application. Thus, it should be emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various positions in this specification are not necessarily referring to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of the application may be combined as suitable.

While the application has been described with reference to the specific embodiments presently, it will be appreciated by those skilled in the art that the foregoing embodiments are merely illustrative of the application, and various equivalent changes and substitutions may be made without departing from the spirit of the application, and therefore, all changes and modifications to the embodiments are intended to be within the scope of the appended claims.

Claims

1. A photo-curable 3D printing device, comprising:

the shell is internally provided with liquid photosensitive resin for forming a workpiece, wherein the inside of the shell is a low-pressure environment lower than atmospheric pressure;

the lifting platform is arranged in the shell and is used for bearing the formed workpiece;

the driving mechanism is positioned outside the shell, the shell is filled with liquid photosensitive resin, the shell is also connected to a piston, the piston is in contact with the liquid photosensitive resin, the piston is connected to a driver, the driver drives the piston to reciprocate, and when the driver drives the piston to move in a direction away from the shell, the negative pressure in the shell is enhanced, so that a workpiece and a contact layer are conveniently separated; when the driver drives the piston to move towards the direction of the shell, positive pressure in the shell is enhanced, so that liquid photosensitive resin flows into a gap between a workpiece and a contact layer formed after the lifting platform is lifted, and accelerated printing is facilitated;

the optical system is positioned below the shell and irradiates a beam pattern, so that a layer of photosensitive resin at the inner bottom of the shell is controllably solidified;

the printing device also comprises an exhaust hole which is opened after the printing task is finished so as to relieve the low-pressure environment inside the shell.

2. The light-curable 3D printing device of claim 1, wherein the bottom of the housing has a contact layer, the contact layer being a non-stick material.

3. The light curable 3D printing device of claim 1, wherein the drive mechanism is a stepper or servo motor connected to the lift platform by a lead screw.

4. The light-curable 3D printing device according to claim 1, wherein the driving mechanism is located above the liquid photosensitive resin inside the housing, and a vacuum hole is provided in the housing, and the vacuum hole is connected to a vacuum pump for pumping the inside of the housing to a low pressure or vacuum lower than the atmospheric pressure.

5. The light-curable 3D printing device according to claim 4, wherein the vacuum hole is further connected to a vacuum gauge for measuring the vacuum degree inside the housing.

6. The light-curable 3D printing device of claim 2, wherein the housing comprises an openable panel or cover plate, the panel or cover plate being sealingly connected to the housing body by a sealing gasket.

7. The light-curable 3D printing device according to claim 1, further comprising a storage tank in which liquid photosensitive resin is stored, the stored liquid photosensitive resin being injected into the housing.