CN116551980A

CN116551980A - Gradient material photo-curing 3D printing equipment and printing method

Info

Publication number: CN116551980A
Application number: CN202310475802.7A
Authority: CN
Inventors: 白家鸣; 袁金斯; 胡博文; 蔡鹏�; 王海江
Original assignee: Southern University of Science and Technology
Current assignee: Southern University of Science and Technology
Priority date: 2023-04-25
Filing date: 2023-04-25
Publication date: 2023-08-08

Abstract

The invention provides gradient material photo-curing 3D printing equipment and a printing method; the gradient material photo-curing 3D printing equipment comprises a printing bearing mechanism, a feeding mechanism, a scraper mechanism and a UV (ultraviolet) ray machine; the gradient material photocuring 3D printing method comprises the steps of model pretreatment, spreading and exposing according to the need; the model preprocessing comprises generating a frame model, slicing files, setting printing parameters and adding material gradient attributes to the three-dimensional model; the motion of the feeding nozzle in the first horizontal direction and the second horizontal direction is controlled in a coordinated manner to extrude the material, and the material is synchronously mixed during spreading, so that gradient spreading according to the requirement is realized; the printing platform descends layer by layer, and the scraper scrapes the liquid level to control the layer thickness; the UV ray machine is controlled to expose on demand through slice file setting. The printing liquid level can be smoothed while feeding, and no leveling waiting time exists; the slurry is directly paved on a printing platform, and printing can be performed by combining the slurry with the required paving and a small amount of slurry; the viscosity application range of the sizing agent is wide; gradient material photo-curing printing can be performed.

Description

Gradient material photo-curing 3D printing equipment and printing method

Technical Field

The invention relates to the field of additive manufacturing, in particular to gradient material photo-curing 3D printing equipment and a printing method.

Background

Photo-curing 3D printing technology is one of the most mature and widely used additive manufacturing technologies at present. Compared with other 3D printing technologies, the method has the advantages of high precision, good surface quality, capability of being directly applied as a functional part to a molded part, capability of molding complex and fine parts and the like. Similar to other 3D printing technologies, the photo-curing 3D printing also uses the principle of layer-by-layer accumulation molding of materials, a three-dimensional model is divided into a plurality of plane sheets by software slicing, and then ultraviolet light beams with certain wavelength are used for selectively curing and molding the photosensitive resin; and finally obtaining the target part through layer-by-layer solidification and accumulation.

The sinking type photo-curing printer has the advantages of wide material adaptability, good model structure performance, difficult deformation and wide application because the influence of the release problem and the gravity action of a printing piece is not needed to be considered. The common sinking type photo-curing printing principle is that after the upper layer is cured, the printing platform is immersed into photo-curing printing slurry for material supplementing, lifted to a certain height, and then the upper and lower fine adjustment of the printing platform is controlled through liquid level calibration, and ultraviolet exposure is carried out after the liquid level is leveled (usually, the printing slurry needs to be fully leveled). The control of the layer thickness during printing is mainly dependent on leveling of the liquid surface and dynamic calibration of the liquid level of the printer.

Since printing paste generally has a certain viscosity and surface tension, when printing is performed by using printing paste with high viscosity, a long leveling waiting time is required (for example, when the leveling waiting time is not long enough, a certain degree of edge deformation phenomenon occurs on the edge of a printing piece, which leads to morphology distortion), and if the leveling capability of the liquid level is not good, the waiting time is very long and even leads to printing failure.

Meanwhile, the submerged photo-curing printing generally requires adding a large amount of photosensitive paste in advance in a cylinder to perform printing, and particularly, a large amount of paste is required when printing higher parts. For printing of valuable slurries, the cost is high; for slurries unsuitable for long-term storage, the material costs are extremely high. Therefore, it is not suitable for printing of new materials, especially valuable functional materials.

In addition, conventional submerged photo-curing printers are not capable of printing gradient materials, limiting the application and development of this technology. The functional gradient material (Functionally Graded Materials, FGM for short) is a novel heterogeneous composite material which adopts advanced material compounding and molding technology to ensure that the composition and structure of the material are changed in a gradient way along a certain direction. The gradient functional material has gradually changed physical properties and can simultaneously respond to various stimuli, so that the gradient functional material has wide application in the fields of sensors, energy storage and power generation, medicaments, intelligent structures, space technology fields and the like. Therefore, further development and application of the gradient material photo-curing printing technology are necessary.

The above problems are technical problems to be solved in the art.

Disclosure of Invention

The invention provides a sinking type gradient material photocuring 3D printing device and a printing method capable of realizing gradient material printing, which can smooth and scrape a printing liquid level while feeding, does not need leveling waiting time and has high printing speed; the slurry is directly paved on a printing platform, and printing can be performed by combining the slurry with the required paving and a small amount of slurry; the extrusion spreading combined with the scraping knife is scraped, and the application range of the viscosity of the sizing agent is wide; flexible feeding and capability of carrying out photo-curing printing of gradient materials.

According to a first aspect, the present application provides a gradient material photocuring 3D printing device, printing with a photocuring 3D printing device, the photocuring 3D printing device comprising:

the printing platform is used for bearing printing pieces and printing slurry;

the feeding mechanism comprises a mixing component and at least two feeding components, the feeding components are communicated with the mixing component, and the mixing component is provided with a feeding nozzle so as to extrude mixed printing paste;

the scraper mechanism is arranged above the printing platform, the scraper mechanism comprises a scraper, the feeding nozzle is positioned at one side of the scraper in a first horizontal direction, the scraper can move along the first horizontal direction, the feeding nozzle can move along the first water direction along with the scraper, the feeding nozzle can independently move along a second horizontal direction to extrude printing slurry, and the first horizontal direction is perpendicular to the second horizontal direction;

The UV light machine is arranged above the printing platform and is configured to project UV light corresponding to the slice pattern of the three-dimensional model to the direction of the printing platform so as to expose and solidify the printing slurry at the uppermost layer of the printing platform according to the requirement;

the photocuring 3D printing method comprises the following steps of:

model pretreatment: adding material gradient attributes to each region of a printing model, wherein the material gradient attributes correspond to the mixing proportion of printing slurry, and generating a frame model which is enclosed outside the printing model in the horizontal direction and is equal to the highest point of the printing model in the vertical direction according to the size of the printing model; combining the frame model and the printing model into one three-dimensional model, slicing the three-dimensional model to obtain a plurality of slice files, confirming the position of a layer to be printed on the printing platform based on the slice files, carrying out gray processing on the slice files based on the material gradient attribute of each area of the slice files, and setting printing parameters for the slice files subjected to gray processing;

printing preparation: adjusting the position of the printing platform to enable the surface of the printing platform to be positioned at the focus of the UV ray machine; adjusting the height of the scraper to enable the bottom of the scraper to be leveled with the top of the printing platform;

Single-layer printing: lowering the printing platform by the height of one layer to be printed, moving the feeding nozzle along the second horizontal direction and extruding printing slurry based on the printing parameters corresponding to the slice file, and simultaneously moving the scraper towards the side provided with the feeding nozzle in the first horizontal direction so as to move the scraper from an initial position to a final position in the first horizontal direction; by coordinated control of the movement of the feed nozzles in a first horizontal direction and a second horizontal direction, to laydown on demand within the layer to be printed; when spreading, controlling printing slurry to be mixed in a mixing component according to a required proportion based on the material gradient property, and extruding the printing slurry; controlling the layer thickness of the layer to be printed through the scraper moving along the first horizontal direction and scraping off the residual materials; curing printing paste, exposing the paste scraped by the scraper according to the requirement by the UV optical machine based on the mixing proportion of the printing paste in each region of the layer to be printed, curing the paste, and resetting the scraper mechanism;

and repeating the single-layer printing step until printing is completed.

In an alternative embodiment, the step of gray processing the slice file based on the material gradient properties of the regions of the slice file comprises: and assigning corresponding gray values to each region of the slice file based on the material gradient properties of each region of the slice file.

In an alternative embodiment, the step of on-demand exposure includes: and respectively irradiating each region of the layer to be printed through a UV (ultraviolet) ray machine based on the gray values of each region of the slice file, and adjusting the exposure intensity and the exposure time of the UV ray machine based on the gray values and the printing parameters corresponding to the irradiated regions to cure the printing paste to obtain a cured layer, wherein the cured layer comprises cured patterns corresponding to the slice patterns of the printing model and the frame model.

In an alternative embodiment, the step of controlling the mixing of the printing paste in the mixing assembly in the desired proportions based on the material gradient properties comprises:

when the feeding nozzle passes through the layer to be printed, the mixing proportion of the printing slurry to be printed is confirmed based on the material gradient attribute corresponding to the area where the feeding nozzle is located, the feeding assembly is controlled to send the corresponding printing slurry into the mixing assembly according to the mixing proportion, and the mixing assembly mixes the printing slurry.

In an alternative embodiment, in the slice file, the slice pattern of the frame model surrounds the periphery of the slice pattern of the print model; and/or the slice pattern of the frame model is square or circular.

In an alternative embodiment, the thickness of the rim model is determined based on the viscosity of the printing paste and the strength of the printed green body, and the thickness of the rim model is 0.5 to 5mm.

In an alternative embodiment, the printing parameters include one or more of a printing pattern, a layer thickness, a printing paste mixing ratio of each region, an exposure intensity, and an exposure time corresponding to each layer to be printed.

In an alternative embodiment, the step of controlling the movement of the feed nozzle in the first horizontal direction and the second horizontal direction by coordination to spread the desired swath within the layer to be printed comprises:

determining a range to be fed based on the position of the layer to be printed on the printing platform; and determining a movement path of the feeding nozzle in a first horizontal direction and a second horizontal direction based on the slice pattern of the layer to be printed, wherein the feeding nozzle moves along the movement path and extrudes printing paste.

According to a second aspect, the present application provides a gradient material photo-curing 3D printing device comprising:

the printing bearing mechanism comprises a printing platform and a lifting assembly, wherein the lifting assembly is connected with the printing platform to drive the printing platform to move in the vertical direction;

The feeding mechanism comprises a mixing component and at least two feeding components, wherein the feeding components are used for containing different printing slurries and are communicated with the mixing component so as to convey the different printing slurries into the mixing component for mixing, and the mixing component is provided with a feeding nozzle so as to discharge the mixed printing slurries;

the scraper mechanism, its set up in the top of print platform, the scraper mechanism includes:

a scraper module, a connecting component, a first moving module and a second moving module,

the scraper module is connected with the first movable module through a connecting component, a second movable module is arranged on the connecting component, the second movable module is positioned at one side of the scraper module in the first horizontal direction, the feeding nozzle is connected with the second movable module,

the first moving module can drive the connecting assembly to move along the first horizontal direction so as to drive the scraper module and the feeding nozzle to move along the first horizontal direction at the same time, and the second moving module can drive the feeding nozzle to move along the second horizontal direction which is perpendicular to the first horizontal direction; and

The UV light machine is arranged above the printing platform and is configured to project UV light corresponding to the slice pattern of the three-dimensional model to the direction where the printing platform is located so as to expose and solidify printing paste at the uppermost layer of the printing platform as required.

In an alternative embodiment, the mixing assembly comprises a mixing container, each of the feeding assemblies is connected to one end of the mixing container, and the feeding nozzle is disposed at the other end of the mixing container.

In an alternative embodiment, the mixing assembly comprises a stirring container, each of the feeding assemblies is communicated with the stirring container, a stirring assembly is arranged in the stirring container, and the feeding nozzle is arranged on one side, away from the feeding assembly, of the stirring assembly.

In an alternative embodiment, the feed assembly includes a storage tank, an extrusion member and a feed pipeline, the storage tank and the mixing assembly are communicated through the feed pipeline, the extrusion member is disposed on the feed pipeline, the storage tank is used for storing printing paste, and the extrusion member is used for enabling the printing paste in the storage tank to be discharged to the mixing assembly.

In an alternative embodiment, the doctor blade module includes a doctor blade, a doctor blade adjustment differential head, and a doctor blade drive assembly; the scraper adjusting micro-head is used for adjusting the relative positions of the scraper and the printing platform before printing starts, so that the top surfaces of the scraper and the printing platform are flush; the scraper is in sliding fit with the connecting component in the vertical direction; the scraper driving assembly is arranged on the connecting assembly and is connected with the scraper to drive the scraper to lift or put down, and the scraper is used for scraping when put down to control the thickness of the printing layer slurry.

In an alternative embodiment, the scraper comprises a blade holder slidably engaged with the connecting assembly and a blade connected to the blade holder.

In an alternative embodiment, the printing device further comprises a residue recovery tank, wherein the residue recovery tank is arranged below the printing platform, and after the residue is scraped by the scraper module, the residue can flow into the residue recovery tank.

In an alternative embodiment, the scraper module further comprises a nozzle mounting piece which is in sliding fit with the connecting assembly in the second horizontal direction and is positioned on one side of the scraper module in the first horizontal direction, and the feeding nozzle is arranged on the nozzle mounting piece; the second moving module is connected with the nozzle mounting piece so as to drive the nozzle mounting piece to drive the feeding nozzle to move along the second horizontal direction.

The beneficial effects of this application lie in: according to the printing device, the scraper module is arranged on the connecting component, the connecting component is used for connecting the feeding nozzle of the feeding component, the feeding nozzle is used for extruding feeding during printing, meanwhile, the scraper and the feeding nozzle are controlled to move together, when the feeding is completed, the printing liquid level can be smoothed, the leveling waiting time is not needed, and the printing efficiency is greatly improved; the slurry is directly paved on a printing platform, and printing can be performed by combining the slurry with the required paving and a small amount of slurry; extrusion spreading combines the scraper to strickle, thick liquids viscosity accommodation is wide, simultaneously, is connected with the feed subassembly through setting up the compounding subassembly, extrudes after mixing printing the thick liquids through the compounding subassembly to can change the proportion of printing the thick liquids at printing the in-process, realize the printing of gradient material.

Drawings

FIG. 1 is an overall schematic diagram of an embodiment of a gradient material photo-curing 3D printing apparatus of the present application;

FIG. 2 is a front view of a gradient material photocuring 3D printing apparatus according to an embodiment of the present application after concealing the cullet;

FIG. 3 is an overall schematic diagram of a doctor blade mechanism in an embodiment of a graded material photo-curing 3D printing apparatus according to the present application;

fig. 4 is a front view of a doctor blade mechanism in an embodiment of a gradient material photo-curing 3D printing apparatus according to the present application

FIG. 5 is a schematic diagram of a doctor blade module in an embodiment of a graded material photo-curing 3D printing apparatus according to the present application;

FIG. 6 is a schematic diagram of a feeding mechanism in an embodiment of a gradient material photo-curing 3D printing apparatus according to the present application;

FIG. 7 is a schematic view of a feeding mechanism in an embodiment of a gradient material photo-curing 3D printing apparatus according to another embodiment of the present application;

FIG. 8 is a schematic flow chart of a printing method according to one embodiment of the present application;

FIG. 9 is a schematic diagram of exposure based on gray values of a slice file;

FIG. 10 is a viscosity profile of a zirconia ceramic printing paste having a solid content of 50 vol%;

fig. 11 is an edge profile of a printed article obtained by printing in an embodiment of the present application.

Reference numerals: the printing machine comprises a frame 1, a printing bearing mechanism 2, a printing platform 21, a lifting assembly 22, a supporting plate 221, a lifting motor 222, a lifting screw 223, a sliding sleeve 224, a lifting guide 225, a light machine 3, a scraper mechanism 4, a scraper module 41, a scraper 411, a cutter holder 411a, a cutter edge 411b, a scraper driving assembly 412, a cam 412a, a scraper motor 412b, a scraper guide 412c, a connecting module 42, a first sliding block 421, a first connecting plate 422, a second connecting plate 423, a first moving module 43, a first guide 431, a first driving belt 432, a first motor 433, a second moving module 44, a second guide 441, a second driving belt 442, a second motor 443, a nozzle mounting member 45, a residual material recycling tank 5, a feeding assembly 6, a storage container 61, a discharge mechanism 62, a feeding pipeline 63, a mixing assembly 7, a feeding nozzle 71, a mixing container 72, a stirring container 73, and a stirring assembly 74.

Detailed Description

The invention will be described in further detail below with reference to the drawings by means of specific embodiments. Wherein like elements in different embodiments are numbered alike in association. In the following embodiments, numerous specific details are set forth in order to provide a better understanding of the present application. However, one skilled in the art will readily recognize that some of the features may be omitted, or replaced by other elements, materials, or methods in different situations. In some instances, some operations associated with the present application have not been shown or described in the specification to avoid obscuring the core portions of the present application, and may not be necessary for a person skilled in the art to describe in detail the relevant operations based on the description herein and the general knowledge of one skilled in the art.

Furthermore, the described features, operations, or characteristics of the description may be combined in any suitable manner in various embodiments. Also, various steps or acts in the method descriptions may be interchanged or modified in a manner apparent to those of ordinary skill in the art. Thus, the various orders in the description and drawings are for clarity of description of only certain embodiments, and are not meant to be required orders unless otherwise indicated.

The sequence numbers themselves, e.g. "first", "second", etc., for the modules herein are used only to distinguish between the described objects and do not have any sequential or technical meaning. The terms "coupled" and "connected," as used herein, are intended to encompass both direct and indirect coupling (coupling), unless otherwise indicated.

The application discloses gradient material photocuring 3D printing equipment, as shown in fig. 1, it is including printing and bear mechanism 2, UV ray apparatus 3 and scraper mechanism 4 and feeding mechanism, and above-mentioned printing bears mechanism 2, UV ray apparatus 3, scraper mechanism 4 and feeding mechanism can integrate to set up in a frame 1.

As shown in fig. 1 and 2, the print supporting mechanism 2 is composed of a print platform 21 and a lifting assembly 22, the print platform 21 is a flat plate structure, and the upper surface of the print platform 21 is used for supporting printing paste and a printing piece formed by the printing paste. The lifting assembly 22 may be installed at the bottom of the printing platform 21 to drive the printing platform 21 to move in the vertical direction. For example, in the example of fig. 2, the lifting assembly 22 includes a support plate 221, a lifting motor 222 is fixedly mounted on the support plate 221, the lifting motor 222 is connected with a vertically disposed lifting screw 223 through a synchronous belt, a sliding sleeve 224 is screwed on the lifting screw 223, and the printing platform 21 is fixedly connected with the sliding sleeve 224; on this basis, the supporting plate 221 is fixed at the bottom of the frame 1 along the vertical direction, one side of the fixing plate is vertically provided with a lifting guide 225, the lifting guide 225 can be a guide member such as a sliding rod or a sliding groove, in this example, the lifting guide 225 is a vertically arranged sliding rail, and the side edge of the printing platform 21 is in sliding fit with the lifting guide 225; so that the printing platform 21 can be forced to move vertically along the elevation guide 225 to be elevated when the elevation screw 223 rotates. It should be appreciated that the lifting assembly 22 may also be, but is not limited to, a cylinder, ram, etc.

In the embodiment disclosed in the application, a feeding mechanism is arranged on the frame 1; referring to fig. 6 and 7, the present application provides a specific feeding mechanism, which includes at least two feeding assemblies 6 and a mixing assembly 7, wherein the feeding assembly 6 is composed of a storage container 61, a discharging mechanism 62 and a feeding pipeline 63, the mixing assembly 7 is directly communicated with the storage container 61 through the feeding pipeline 63, and the discharging mechanism 62 is disposed in the middle of the feeding pipeline 63 so that printing paste in the storage container 61 can be discharged to the mixing assembly 7 through the storage pipeline; as shown in fig. 6 and 7, the discharge mechanism 62 may be a peristaltic pump that presses the feed pipe 63 through rollers, so that a negative pressure is formed in the feed pipe 63 to enable the printing paste in the reservoir 61 to be pumped toward the mixing assembly 7, and a feed nozzle 71 is provided at an end of the mixing assembly 7 remote from the feed assembly 6, through which the mixed printing paste can be extruded.

On this basis, in some examples, as shown in fig. 6, the mixing assembly 7 includes a mixing container 72, for example, the mixing container 72 may be an elongated mixing rubber tube, the upper end of the mixing container 72 is connected to the feeding pipe 63 in each feeding assembly 6 at the same time to receive the printing paste discharged from the storage container 61, the bottom of the mixing container 72 is used as the feeding nozzle 71, and when the printing paste enters the mixing container 72, the printing paste is self-mixed in the mixing container 72; during printing, the discharge amount of printing paste in each storage container 61 can be controlled by the discharging mechanism 62 based on the required material gradient (i.e. printing paste mixing ratio), so that feeding according to different printing paste mixing ratios can be realized.

Considering that when the paste is self-mixed by printing, since the mixing container 72 is directly connected with the feeding nozzle 71 and the feeding pipeline 63, a certain transition is formed in the mixing container 72 when the proportion of the paste is changed, and then a certain delay exists; thus, in other examples, as shown in fig. 7, the mixing assembly 7 may be comprised of a mixing vessel 73 and a mixing assembly 74 disposed within the mixing vessel 73. For example, the stirring vessel 73 may be a horizontally disposed cylinder, and a stirring assembly 74 such as a stirring paddle is disposed inside the cylinder, and the feeding nozzle 71 is located at an end of the stirring assembly 74 away from the feeding assembly 6. In this example, when the material enters the stirring vessel 73, the different printing pastes can be fully mixed by stirring of the stirring assembly 74, and when the proportion of the printing pastes is changed, the material needs to be mixed first, so that a transition section is not present, and further, the delay change of the mixing proportion of the printing pastes does not occur.

Referring again to fig. 1 and 2, in the embodiment disclosed herein, a UV light engine 3 is fixed on top of the frame 1 and is located above the print carrier 2, and the UV light engine 3 has a light outlet opposite to the print platform 21 to project UV light toward the direction in which the print platform 21 is located.

Referring to fig. 1 and 2, the doctor mechanism 4 is located between the printing platform 21 and the UV light machine 3; as shown in fig. 3 and 4, the doctor mechanism 4 is composed of a doctor module 41, a connection assembly 42, a first moving module 43 and a second moving module 44. The scraper module 41 is mounted on the connecting assembly 42, the connecting assembly 42 is connected to the first moving module 43, and the first moving module 43 drives the connecting plate to move on a horizontal plane. A second moving module 44 is mounted on one side of the connection assembly 42, and the second moving module 44 is used for mounting a feeding nozzle 63 (shown in fig. 6 and 7) of the feeding mechanism 6, and the second moving module 44 can drive the feeding nozzle 63 to move along a horizontal plane, wherein the moving direction of the feeding nozzle 63 and the overall running direction of the connection assembly 42 are mutually perpendicular in the horizontal plane.

In a specific example, with continued reference to fig. 3 and 4, the connection assembly 42 is formed by two parallel connection boards, and the two connection boards are connected by a first slider 421, for example, the first slider 421 may be installed at two ends of the two connection boards, so that the two connection boards can keep synchronous; for convenience of description, the direction in which the first moving module 43 drives the connection assembly 42 to move is defined as a first horizontal direction, and the two connection plates are defined as a first connection plate 422 and a second connection plate 423, respectively. In this example, the second connecting plate 423 is disposed on one side of the first connecting plate 422 in the first horizontal direction, the first moving module 43 is disposed at two ends of the first connecting plate 422 and the second connecting plate 423, specifically, the first moving module 43 includes a first guide member 431 extending along the first horizontal direction (for example, the first guide member 341 may be a sliding rail, a sliding rod, etc.), and a first driving assembly that controls the movement of the connecting assembly 42, where the sliding block in the connecting assembly 42 is slidably engaged with the first guide member 431, the first driving module includes a first driving belt 432 disposed along the first horizontal direction and a first motor 433 that drives the first driving belt 432 to move, and the first motor 433 is connected to the first driving belt 432 through a plurality of synchronous members (for example, synchronous belts, etc.) so as to drive the first driving belt 432 disposed at two sides of the connecting assembly 42 to operate synchronously, and the first driving belt 432 is fixedly connected to the first sliding block 421, so that when the first driving belt 432 rotates, the first sliding block 421 can be driven to operate along the first guide member 431, and thus drive the connecting assembly 42 to operate.

With continued reference to fig. 3, 4, 6 and 7, the second moving module 44 is disposed on the second connecting plate 423, and illustratively, the second connecting plate 423 is provided with a nozzle mounting member 45, the nozzle mounting member 45 is provided with a slot for fixing the feeding nozzle 63 of the feeding assembly 6, and the nozzle mounting member 45 is slidably engaged with the connecting assembly 42 in a second horizontal direction perpendicular to the first horizontal direction in a horizontal plane; the nozzle mount is located at one side of the scraper 411 in the first horizontal direction, and the feed nozzle 63 is provided on the nozzle mount 45; the second moving module 44 is connected with the nozzle mounting piece 45 to drive the feeding nozzle 63 to move along the second horizontal direction; the second moving module 44 includes a second guide member 441 (e.g., a sliding rail, a sliding rod, etc.) extending along a second horizontal direction, and a second driving assembly for controlling the movement of the nozzle, the nozzle mounting member 45 is slidably engaged with the second guide member 441, the second driving module includes a second driving belt 442 disposed along the second horizontal direction and a second motor 443 for driving the second driving belt 442 to move, and an output end of the second motor 443 is directly connected with the second driving belt 442 to drive the second driving belt 442 to operate, so that the nozzle mounting member 45 can be driven to operate along the second guide member 441 when the second driving belt 442 rotates, and further the feeding nozzle 63 is driven to move along the second horizontal direction.

It is to be understood that the first moving module 43 and the second moving module 44 are not limited to the structure disclosed in the above example, and the first moving module 43 and the second moving module 44 may also adopt other linear driving modules; for example, the cylinder, the screw motor, etc., can be adaptively selected and laid out in the art based on actual requirements, and the application is not limited too much.

In the example disclosed herein, referring to fig. 5, the doctor module 41 is composed of a doctor 411 and a doctor driving assembly 412, and the doctor 411 is slidably engaged with the connection assembly 42 and connected to the doctor 411 to drive the doctor 411 to move in a vertical direction. Referring to the example of fig. 5, in which the doctor blade is mounted on the first connection plate 422, in particular, the doctor blade driving assembly 412 includes a doctor blade guide 412c vertically disposed on the first connection plate 422, the doctor blade guide 412c may be, but is not limited to, a slide rail, a slide bar, etc., and the doctor blade 411 is slidably engaged with the doctor blade guide 412c in a vertical direction; more specifically, the doctor blade is composed of a blade holder 411a and a blade 411b, wherein the blade 411b is mounted at the bottom end of the blade holder 411 a; the blade holder 411a is slidably matched with the blade guide 412c, a driving through hole is formed in the middle of the blade holder 411a, the blade driving assembly 412 further includes a cam 412a disposed in the driving through hole and capable of vertically rotating, and a blade motor 412b for driving the cam 412a to move, when a protrusion of the cam 412a rotates upwards, the blade holder 411a can be lifted, and when the cam 412a rotates downwards, the blade holder 411a can be driven to move downwards, so that the blade 411 as a whole can move in a vertical direction. It should be understood that the doctor driving assembly 412 may also be configured by a cylinder, an oil cylinder, a screw motor, etc., which is not limited in this application.

Considering that the doctor blade drive assembly 412 can only adjust the vertical position of the doctor blade over a wide range, in some alternative designs, to more finely adjust the position of the blade edge 411b in the doctor blade, the doctor blade 411 includes a doctor blade adjustment differential head (not shown) for adjusting the relative positions of the doctor blade and the print platen before printing begins so that the doctor blade and the print platen top surface are flush. For example, the doctor blade adjustment differential head may be a micrometer adjustment differential head fixed to the first connection plate 422, which is not excessively limited in this application.

In some alternative designs, referring to fig. 1 and 2, the frame 1 is further provided with a remainder recycling tank 5, specifically, the remainder recycling tank 5 is a square tank with an open top, and is disposed below the printing platform 21.

This application is in the during operation, because feed nozzle 63 and scraper 411 all are located coupling assembling 42, therefore when printing, can order about coupling assembling 42 along first horizontal direction towards the one side motion that is provided with feed nozzle 63, order about feed nozzle 63 simultaneously along the second horizontal direction and remove, because first horizontal direction perpendicular to second horizontal direction, in this process, through the removal route of first removal module 43 and second removal module 44 control feed nozzle 63 and coupling assembling 42, can make the whole printing area of feed nozzle 63 route, realize extruding the feed, simultaneously, scraper 411 also can be synchronous will print the thick liquids and strickle, control the thickness of printing thick liquids, need not the levelling latency.

In operation, the specific printing method is shown in fig. 8, and comprises the following steps:

step S101: establishing a printing model with three-dimensional space coordinates, and adding material gradient attributes to the printing model; and establishing a virtual printing model of the required printed piece through computer modeling software, and adding material gradient properties to the printing model according to the required printing slurry mixing proportion of different areas of the printing model. Preprocessing a printing model, and generating a frame model which is enclosed outside the printing model in the horizontal direction and is equal to the highest point of the printing model in the vertical direction according to the size of the printing model; and combining the frame model and the printing model into one three-dimensional model.

When the printing method is used for establishing the printing model, a printing area corresponding to the printing piece to be printed and a frame model for supporting the printing piece are arranged in the printing model, the frame model is enclosed outside the printing area, the height of the frame model is equal to the height of the printing model, and the frame model is enclosed on the periphery of the printing model.

According to the model size of the printing piece, a frame for protecting printing paste is designed to surround the printing piece; and the height of the designed frame model is equal to the height of the printed piece. In the printing process, the frame model can be synchronously printed and formed along with the printing piece, the frame model can be used for limiting the area of the printing piece, the sizing agent in the printing area is reserved, the protective frame model surrounds the piece to be printed, and a liquid level support is formed for the printing sizing agent to be solidified in the printing area.

Wherein the thickness of the frame model is determined based on the viscosity of the printing paste and the strength of the printed green body (i.e., the printed article after printing but without post-treatment), preferably, the model of the frame is 0.5 to 5mm.

The material gradient attribute is an attribute parameter corresponding to the mixing proportion of the printing paste required, can be manually input, can be directly obtained through calculation by the existing algorithm, and can be applied to the application as long as the specific value taking mode and the expression mode of the material gradient attribute are not excessively repeated and limited and one-to-one correspondence of the material gradient attribute and the mixing proportion of the printing paste is met.

Step S102: slicing the printing model, and dividing the printing model into a plurality of layers of slicing files corresponding to the layers to be printed one by one in the vertical direction. And print parameters of each layer to be printed are set based on the sections (slice patterns) of the print area and the frame area on the respective slice files.

In the step, the printing model is divided into a plurality of slice files which are continuously arranged in the vertical direction according to the performance of printing paste by using computer modeling software, the printing model is mapped above the printing platform 21 according to the three-dimensional space coordinates of the printing model, a plurality of layers to be printed which are in one-to-one correspondence with the slice files are preset above the printing platform 21, and the printing parameters of the corresponding printing layers are determined according to the sections of the printing area and the frame model area on each slice file.

By way of example, the printing parameters may include one or more of the following, such as:

corresponding to the print pattern (i.e., the cross-sectional pattern of the slice file), layer thickness (height of the single layer to be printed), exposure intensity, and exposure time; the feed nozzle 63 can then plan its path of movement in the first horizontal direction and the second direction based on the printing parameters, and control the feed. .

Step S103: and carrying out gray processing on the slice file, forming a plurality of areas with different gray values on the slice file according to the material gradient attribute on the slice file, determining the printing paste mixing proportion of each area of the corresponding layer to be printed based on the material gradient attribute of each area of the slice file, and determining the exposure parameters based on the gray values of each area of the slice file.

In this step, after slicing the print model, different gray values may be assigned to each region on the slice file according to the material gradient properties corresponding to the different regions on the slice file based on the existing image processing technology.

For example, when mixed printing is performed using a material a and a material B as printing pastes, when the printing pastes required for a region on a slice document are all the material a, the gradation value of the region may be set to x1 (corresponding to the material a printing parameter), when the printing pastes required for a region on a slice document are all the material B, the gradation value of the region may be set to x2 (corresponding to the material B printing parameter), and when the materials required for a region on a slice document are mixed of the materials a and B, the gradation value of the region may be given based on the ratio of a and B.

When printing is performed, the required printing slurry mixing proportion corresponding to each region on the layer to be printed can be obtained according to the preset corresponding relation between the material gradient attribute of each region of the slice file and the printing slurry mixing proportion; and acquiring exposure parameters required by corresponding areas on the layer to be printed according to the gray values on the corresponding slice files. A schematic diagram of exposure according to the gray value is shown in fig. 9.

Step S2: printing preparation: the height of the printing platform 21 is adjusted through the lifting mechanism, so that the surface of the printing platform is positioned at the focus of the UV light machine 3; the differential head is adjusted by the doctor blade drive assembly 412 and the trimming doctor blade so that the bottom of the doctor blade is level with the top with the platform. .

Step S3: single-layer printing: lowering the printing platform by one height of the layer to be printed, moving the feeding nozzle 63 along the second horizontal direction and extruding printing paste based on printing parameters corresponding to the slice document, and simultaneously moving the scraper 411 towards the side provided with the feeding nozzle 63 in the first horizontal direction so that the scraper 411 moves from an initial position to a final position in the first horizontal direction; by coordinated control of the movement of the feed nozzles 63 in a first horizontal direction and a second horizontal direction to layup on demand within the layer to be printed; when spreading, according to the material gradient properties of each area of the slice file, controlling the printing paste to be mixed in a mixing component according to the required proportion, and extruding the printing paste; and controlling the layer thickness of the layer to be printed by the doctor blade 411 moving in the first horizontal direction and scraping off the residual material; and curing printing paste, namely exposing the paste scraped by the scraper 411 according to the requirement through the UV light machine 3 based on the mixing proportion of the printing paste in each region of the layer to be printed, curing the paste, and resetting the scraper 411 and the feeding mechanism.

In this step, the movement paths of the connection assembly 42 and the feeding nozzle 63 are all performed according to the input printing parameters, and since the feeding nozzle 63 is mounted on the connection assembly 42, the feeding nozzle 63 can synchronously move along the first horizontal direction along with the connection assembly 42, and at the same time, the feeding nozzle 63 can move along the second horizontal direction, so that when the connection assembly 42 moves along the preset path in the first horizontal direction, the feeding nozzle 63 can move along the whole area of the layer to be printed. In this process, since the doctor 411 and the feed nozzle 63 move synchronously, and the feed nozzle 63 is located in front of the movement direction of the doctor 411, the functions of leveling the liquid surface, precisely controlling the layer thickness, and removing the surplus slurry can be simultaneously realized in the feeding process, and the surplus slurry can be scraped off the feed platform by the doctor 411, thereby entering the surplus slurry recovery tank 5.

In the process that the feeding nozzle 71 moves along the layer to be printed, the mixing proportion of printing slurry in the corresponding area of the layer to be printed is obtained based on the material gradient attribute of each area of the slice file corresponding to the layer to be printed, so that each feeding component 6 filled with different printing slurries is controlled to feed into the mixing component 7, and the provided mixing proportion of the printing slurries is matched with the required mixing proportion of the printing slurries; in curing, the parameters of exposure may also be used as part of the printing parameters, which are determined based on the gray values of the various regions in the slice file when the slicing process is performed.

Specifically, the light machine may adopt a DLP projector, and when exposure is performed, according to the mixing proportion of printing pastes of each region on the layer to be printed, the DLP projector selects corresponding exposure parameters to expose each region of the layer to be printed.

Repeating the single-layer printing until the printing is completed; removing the frame to obtain a printing piece; and cleaning, drying, post-curing and the like are carried out on the printing piece.

According to the printing device, the connecting component 42 is arranged, so that the scraper mounting and feeding nozzles 63 can be simultaneously mounted on the connecting component 42, printing slurry can be synchronously scraped in the printing feeding process, and further liquid level detection, feedback and leveling waiting time are not needed, so that the printing speed is greatly improved, and the printing time benefit is improved; on the other hand, the thickness of the printing paste is controlled by the extrusion feeding matched with the scraper, the viscosity of the printing paste is not limited, and the printing paste is suitable for printing pastes with various viscosities.

In the conventional submerged photo-curing printing device, a sufficient amount of printing paste needs to be filled in the resin tank in advance, and the printing paste needs to be continuously lowered through the printing platform to be replenished during printing. Compared with the traditional sinking type photocuring printing device, the printing device has the advantages that printing paste does not need to be filled in advance in the printing mode of extrusion feeding, the outer frame is designed to support the liquid level of the printing paste, and the printing paste can be remarkably saved. And traditional submerged photocuring printing device still need set up liquid level detection and feedback system, and the structure is comparatively complicated. The liquid level detection and feedback system is not needed, and the liquid level detection and feedback system is simple in structure and low in cost.

The method has the characteristic of high morphology fidelity. Because the slurry generally has certain viscosity and surface tension, when the viscosity of the slurry is not low enough and the leveling waiting time is not long enough, the edge of the printing piece printed by adopting the traditional sinking type photo-curing can be deformed to a certain extent, and the appearance is distorted. The printing device and the printing method can well provide liquid level support for the printing piece because the outer frame generated by synchronous printing is used as the slurry fence, so that the printing piece has no edge deformation and high shape fidelity.

The printing device is suitable for printing of gradient materials, and the mixing assembly 7 is connected with the plurality of feeding assemblies 6, and the printing slurry is mixed and extruded by the mixing assembly 7, so that the proportion of the printing slurry can be changed in the printing process, and the printing of the gradient materials is realized; the leveling property and viscosity requirements on the slurry are low, the printing parameters can be planned according to different slurries, the mixing proportion of the printing slurry can be switched, accurate feeding is realized, the material waste is reduced, the printing cost is reduced, and the printing benefit is improved.

For ease of explanation of the present application, the present application provides the following specific examples:

embodiment one:

the photo-curing printing of the gradient material is carried out according to the method disclosed by the application by adopting two materials, namely photosensitive resin containing plastic microbeads and hydroxyapatite ceramic slurry, as printing slurry. Wherein, the plastic microbeads are pore-forming materials, and the hydroxyapatite is a common ceramic material.

In the step of performing monolayer printing, in the feeding stage, the feeding assembly 6 containing hydroxyapatite slurry has a constant feeding speed through the feeding pipeline 63, and the feeding assembly 6 containing photosensitive resin with plastic microbeads has a variable speed feeding mode, and the feeding speed is gradually slowed down, so that the material gradient of the printed part is gradually changed.

After printing, cleaning, drying, degreasing, sintering and the like are carried out on the printing piece, and finally the printing piece with the gradient structure with gradually increased densification degree from bottom to top is obtained. The gradient pore ceramic structure can generate special mechanical properties according to the gradient change of the material proportion, and has wide application prospects in the fields of biological medical treatment and the like.

Embodiment two:

a homemade 50vol% solids zirconia ceramic printing paste was used, the viscosity profile of which is shown in fig. 10, which has suitable rheological properties for printing with a conventional submerged photo-curing printer.

The photo-curing 3D printing device, the printing method and the traditional sinking photo-curing printer disclosed by the application are used for printing the printing paste, and the morphology diagram of the finally obtained printing piece is shown in fig. 10.

Fig. 11a is an edge profile of a printed article obtained by using a conventional submerged photo-curing printer, and fig. 11b is an edge profile of a printed article obtained by using the photo-curing 3D printing device and the printing method disclosed in the application. As can be seen from fig. 11a and 11b, the edge of the printed piece obtained by the conventional submerged photo-curing printer has a phenomenon of edge collapse and shape distortion to a certain extent; the edge of the printing piece prepared by the photo-curing 3D printing device and the printing method is flat and has no shape distortion. The photo-curing 3D printing device and the printing method provided by the invention are adopted to prepare the printing piece, and the printing piece has the characteristics of no edge deformation and high shape fidelity.

Compared with the traditional sinking type photocuring printing method, the photocuring 3D printing method disclosed by the application is used for completing the same printing piece, a large amount of slurry is required to be poured into the slurry cylinder in the traditional sinking type photocuring printing method, and the method disclosed by the application does not need to pour the slurry into the slurry cylinder completely, so that the consumption of printing the slurry can be effectively reduced. Meanwhile, by the photocuring 3D printing method, leveling waiting time is not needed, and printing efficiency can be effectively improved.

The foregoing description of the invention has been presented for purposes of illustration and description, and is not intended to be limiting. Several simple deductions, modifications or substitutions may also be made by a person skilled in the art to which the invention pertains, based on the idea of the invention.

Claims

1. The gradient material photocuring 3D printing method is characterized in that a photocuring 3D printing device is adopted for printing, and the photocuring 3D printing device comprises:

the printing platform is used for bearing printing pieces and printing slurry;

the photocuring 3D printing method comprises the following steps of:

model pretreatment: adding material gradient attributes to each region of a printing model, wherein the material gradient attributes correspond to the mixing proportion of printing slurry, and generating a frame model which is enclosed outside the printing model in the horizontal direction and is equal to the highest point of the printing model in the vertical direction according to the size of the printing model; combining the frame model and the printing model into a three-dimensional model, slicing the three-dimensional model to obtain a plurality of slice files, confirming the position of a layer to be printed on the printing platform based on the slice files, carrying out gray processing on the slice files based on the material gradient attribute of each region of the slice files, and setting printing parameters for the slice files subjected to gray processing;

Single-layer printing: lowering the printing platform by the height of one layer to be printed, moving the feeding nozzle along the second horizontal direction and extruding printing slurry based on the printing parameters corresponding to the slice file, and simultaneously moving the scraper towards the side provided with the feeding nozzle in the first horizontal direction so as to move the scraper from an initial position to a final position in the first horizontal direction; by coordinated control of the movement of the feed nozzles in a first horizontal direction and a second horizontal direction, to laydown on demand within the layer to be printed; when spreading, controlling printing slurry to be mixed in a mixing component according to a required proportion based on the material gradient property, and extruding the printing slurry; the thickness of the layer to be printed is controlled by the scraper moving along the first horizontal direction, and the residual material is scraped off; curing printing paste, exposing the paste scraped by the scraper according to the requirement by the UV optical machine based on the mixing proportion of the printing paste in each region of the layer to be printed, curing the paste, and resetting the scraper mechanism;

and repeating the single-layer printing step until printing is completed.

2. The photo-curing 3D printing method of claim 9, wherein the step of gray-scale processing the slice file based on the material gradient properties of each region of the slice file comprises: and assigning corresponding gray values to each region of the slice file based on the material gradient properties of each region of the slice file.

3. The light-curable 3D printing method according to claim 2, wherein the step of on-demand exposure comprises: and respectively irradiating each region of the layer to be printed through a UV (ultraviolet) ray machine based on the gray values of each region of the slice file, and adjusting the exposure intensity and the exposure time of the UV ray machine based on the gray values and the printing parameters corresponding to the irradiated regions to cure the printing paste to obtain a cured layer, wherein the cured layer comprises cured patterns corresponding to the slice patterns of the printing model and the frame model.

4. The method of photocuring 3D printing according to claim 2, wherein the step of controlling the mixing of the printing paste in the mixing assembly in a desired ratio based on the gray scale processed slice file comprises:

5. The light-curable 3D printing method according to claim 1, wherein in the slice file, the slice pattern of the frame model surrounds the periphery of the slice pattern of the print model; and/or the slice pattern of the frame model is square or circular.

6. The photo-curing 3D printing method according to claim 1, wherein the thickness of the frame model is determined based on the viscosity of the printing paste and the strength of the printed green body, and the thickness of the frame model is 0.5 to 5mm.

7. The photo-curing 3D printing method according to claim 1, wherein the printing parameters include one or more of a printing pattern, a layer thickness, a printing paste mixing ratio of each region, an exposure intensity, and an exposure time corresponding to each layer to be printed.

8. The method of photo-curing 3D printing of claim 1, wherein the step of on-demand tiling within the layer to be printed by coordinated control of the movement of the feed nozzle in a first horizontal direction and a second horizontal direction comprises:

9. A gradient material photo-curing 3D printing apparatus, comprising:

10. The gradient material light-curing 3D printing apparatus of claim 9, wherein the mixing assembly comprises mixing containers, each of the feeding assemblies is connected to one end of the mixing container, and the feeding nozzle is disposed at the other end of the mixing container.

11. The gradient material light-curing 3D printing apparatus of claim 9, wherein the mixing assembly comprises a stirring vessel, each of the feed assemblies is in communication with the stirring vessel, a stirring assembly is disposed in the stirring vessel, and the feed nozzle is disposed on a side of the stirring assembly away from the feed assemblies.

12. The gradient material light-curing 3D printing apparatus of claim 10 or 11, wherein the feed assembly comprises a storage tank, an extrusion member and a feed pipeline, the storage tank and the mixing assembly are communicated through the feed pipeline, the extrusion member is disposed on the feed pipeline, the storage tank is used for storing printing paste, and the extrusion member is used for discharging the printing paste in the storage tank to the mixing assembly.

13. The gradient material light-curing 3D printing apparatus of claim 9, wherein the doctor blade module comprises a doctor blade, a doctor blade adjustment differential head, and a doctor blade drive assembly; the scraper adjusting micro-head is used for adjusting the relative positions of the scraper and the printing platform before printing starts, so that the top surfaces of the scraper and the printing platform are flush; the scraper is in sliding fit with the connecting component in the vertical direction; the scraper driving assembly is arranged on the connecting assembly and is connected with the scraper to drive the scraper to lift or put down, and the scraper is used for scraping when put down to control the thickness of the printing layer slurry.

14. The gradient material light-curing 3D printing apparatus of claim 13, wherein the doctor blade includes a blade seat and a blade edge, the blade seat being in sliding engagement with the connection assembly, the blade edge being connected to the blade seat.

15. The gradient material light-curing 3D printing apparatus of claim 9, further comprising a cullet recycling tank disposed below the printing platform, the cullet recycling tank being capable of flowing cullet into the cullet recycling tank after the cullet is scraped by the doctor blade module.

16. The gradient material light-curing 3D printing apparatus of claim 9, further comprising a nozzle mount slidably engaged with the connection assembly in the second horizontal direction and located on a side of the doctor blade module in the first horizontal direction, the feed nozzle being disposed on the nozzle mount; the second moving module is connected with the nozzle mounting piece so as to drive the nozzle mounting piece to drive the feeding nozzle to move along the second horizontal direction.