CN116175730B - Improved method and device for roller scraper in photo-cured ceramic 3D printing spreading - Google Patents
Improved method and device for roller scraper in photo-cured ceramic 3D printing spreading Download PDFInfo
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- CN116175730B CN116175730B CN202310295168.9A CN202310295168A CN116175730B CN 116175730 B CN116175730 B CN 116175730B CN 202310295168 A CN202310295168 A CN 202310295168A CN 116175730 B CN116175730 B CN 116175730B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/001—Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/29—Producing shaped prefabricated articles from the material by profiling or strickling the material in open moulds or on moulding surfaces
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B17/00—Details of, or accessories for, apparatus for shaping the material; Auxiliary measures taken in connection with such shaping
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
Abstract
The invention provides an improved method and device for a roller scraper in a photo-cured ceramic 3D printing spreading material. An improved method of a roller doctor blade in a photo-cured ceramic 3D printing blanket comprises: s1, establishing a fluid domain geometric model of a roller scraper in the process of photocuring ceramic 3D printing spreading; s2, obtaining technological parameters; s3, setting a physical field, setting boundary conditions, dividing grids and setting a solver for the geometric model of the fluid domain according to the process parameters; s4, changing structural parameters of the roller scraper in the fluid domain geometric model for multiple times, and calculating respectively to obtain pressure values before a plurality of scrapers; s5, determining structural parameters of the scraper corresponding to the pressure value before the minimum scraper according to the pressure values before the plurality of scrapers. The proper position of the roller relative to the scraper is determined through analysis, so that the pressure before the scraper is reduced, the deformation of the solid is reduced, the manufacturing precision and the printing success rate of the printed parts are improved, and the research and development efficiency and the improvement efficiency of the roller scraper spreading device are improved.
Description
Technical Field
The invention relates to the technical field of 3D printing of photo-cured ceramics, in particular to an improved method and device for a roller scraper in 3D printing of photo-cured ceramics.
Background
Most of the traditional ceramic forming technologies can only produce corresponding ceramic parts by means of a die, and the design and production of the die consume a great deal of time and cost, so that the convenient and flexible production targets cannot be realized. And for complex ceramic parts, such as parts with fine structures and internal porosity, corresponding molds cannot be quickly designed at present, which limits the production of complex ceramic parts. It is known that the conventional ceramic molding method cannot meet the increasing demands of the fields of biomedicine, aerospace and the like on complex ceramic parts. In order to solve the limitations of the traditional ceramic forming method, researchers have proposed ceramic additive manufacturing, and have completed the manufacture of various ceramic products with complex structures by utilizing the ceramic additive manufacturing technology. In many ceramic additive manufacturing technologies, photo-curing 3D printing stands out because the photo-curing 3D printing has the characteristics of high precision, good mechanical property, high density and the like of ceramic products.
The principle of ceramic photo-curing 3D printing is as follows: firstly, controlling a laser to emit downward, and selectively irradiating the uppermost ceramic photosensitive slurry in a material tank to finish the single-layer solidification of the ceramic material; then, the workbench is controlled to descend, a layer of ceramic material is coated on the solid surface again by using a coating tool, and the next curing is continued; repeating the above solidifying process until the final solid model is obtained.
The photocuring process can be known that the step of spreading the ceramic slurry by using the coating tool is necessary, and is very important, and is one of key steps for directly limiting the printing precision and the printing success rate.
In the preparation of ceramic pastes before photo-curing printing, researchers have tended to formulate high viscosity ceramic pastes because high viscosity ceramic pastes have some self-supporting properties during printing and less shrinkage during degreasing sintering. However, the high-viscosity ceramic has low fluidity and high viscosity, so that a high acting force is generated on the lower solid (cured layer) in the spreading process, and the printing part is sometimes deformed and damaged, so that the printing process is interrupted.
To address the above problems, the prior art has proposed solutions for improving the spreading process: the past spreading devices have been based on the use of a doctor blade alone, and existing spreading modifications have been developed around the device not only using a doctor blade, but also adding a roller/screw (hereinafter referred to as a roller) at the front end of the doctor blade. The roller which is placed at the front end of the scraper can increase the fluidity of the slurry before the scraper, and the pressure of the cutting edge of the scraper can be reduced, so that the interlayer combination of printing parts is firmer, and the use requirements of ceramic slurries with different viscosities are met. The skilled person does not further describe the rotational speed, the turning direction, the diameter size, the mounting position with respect to the doctor blade of the roll. If the size, turning or mounting position of the rollers is not the same, the pressure caused by the spreading process is increased and negative effects are caused. The lack of a certain technical support in the design of the roller blade or the great structural improvement results in a high cost.
The prior patent I: active control of viscosity of ceramic slurry for 3D printing doctor blade system (CN 202210662790.4, CN114986654 a): the slurry scraping device comprises a scraping device and a roller arranged in the advancing direction of the scraping device, wherein the movement direction of slurry right below the roller, which is generated after the roller rotates, is consistent with the scraping direction of the scraping device. The viscosity of high viscosity ceramic slurry is reduced through the rotary motion of the roller, so that the 3D printing equipment is not affected by the viscosity of the ceramic slurry any more, the printing success rate and the size precision of a printing piece are improved, the pressure of the cutting edge of the scraper can be reduced through the structural design of the first patent, the interlayer bonding of the printing piece is firmer, and the use requirements of the ceramic slurry with different viscosities are met.
The content analysis for patent one is as follows:
the roller is positioned in the advancing direction of the scraping device, in particular in the advancing direction of the scraper, and the advancing direction of the scraper is the spreading direction of the scraping device. The roller and the first motor on the slide plate device are kept to synchronously rotate through the driving belt, the first motor is used for actively controlling the rotation speeds of the roller, the slurry passing through the rotation of the roller can be subjected to shear thinning, the viscosity of the slurry when being paved by the scraper is reduced, and the printing requirements of the device on slurries with different viscosities are met.
The roller in the high-speed rotation makes the thick liquids all have mobility in the surrounding area to the direction of motion that the thick liquids produced after the roller rotates is the same with scraping device's shop direction under the roller, and the appearance of this phenomenon can reduce the resistance of thick liquids to the scraper, finally reduces the pressure of scraper to thick liquids, and then reduces the printing part and is pushed down by the scraper in the printing process risk, makes the thick liquids spread more smoothly to the printing face.
The roller is used for assisting the scraper, enough slurry is reserved for paving the scraper, so that the distance between the roller and the printing platform is larger than that between the scraper and the printing platform.
The disadvantage of the first patent: 1. the rotating speed direction of the bottom of the roller is the same as the moving direction of the scraper, at the moment, the roller only acts by shear thinning to reduce the viscosity of the slurry before the scraper, but the front pressure generated when the scraper moves is not fundamentally resisted, and if the front pressure generated by the scraper is resisted, the direction of the resisting force must be leftward (the value is smaller than the front pressure); the distance between the roller and the printing platform is larger than the distance between the scraper and the printing platform, and the roller is slightly higher in distance, so that larger roller force can be prevented from being introduced, but the slurry close to the surface of the solidified layer cannot be driven by the higher roller, so that the installation position of the roller is very important, and the related size parameters and installation parameters of the roller are not specified in the first patent.
The prior patent II: paving system of 3D printing apparatus (CN201910136735.X, CN109702854 a): the second patent discloses a paving system of 3D printing equipment, which comprises a paving device, a driving device for driving the paving device and a supporting platform for supporting the paving device; the paving device includes: the support part comprises two support seats which are oppositely arranged, and a certain distance is reserved between the two support seats; the supporting seat is connected with the driving device through the conveying belt so that the supporting part moves under the driving of the driving device; the scraping part is in a reverse U shape, extends along the direction perpendicular to the running direction of the supporting part, is sleeved on the periphery of the supporting part, and two ends of the scraping part in the extending direction are respectively hinged with the two supporting seats so as to enable the scraping part to alternately move up and down on two opposite sides of the moving direction of the supporting part, and bidirectional scraping of the scraping part is realized. The advantages are that: the design structure of the double scrapers can realize repeated forward and reverse double scraping and improves the printing efficiency; the grooving roller and the screw are designed to improve the spreading quality of the slurry.
In the second patent, the technical staff selects the pi-shaped scraper and selects the roller and the screw as auxiliary tools for spreading, wherein the screw mainly plays a role in stirring to reduce the viscosity of the slurry, and the main role of the roller is to reduce the pressure generated at the front end of the scraper. The device is novel, but the whole is more complicated, in the practical application process, if the relevant parameters of the roller and the scraper can be controlled, the roller is only used, the screw is not required to be installed, the installation operation is simplified, the spreading force generated by the screw can be brought by the introduction of the screw, and the spreading of high-viscosity slurry is not friendly.
The disadvantage of the second patent: 1. no parameters or references are given for the mounting of the roller and the doctor blade, the relative position of the two has a great influence on the stress of the solid in the process of spreading the high viscosity, and if the adjustment is poor, the effect is reacted. 2. The screw is introduced into the device, which is equivalent to introducing a force, and the solid is influenced in the spreading process. And are more complex in terms of mechanical design, mechanical installation, control, etc.
As shown in fig. 4 and 5, only the doctor blade (bevel blade) generates a large force at the front end of the doctor blade during the spreading process. As shown in fig. 6, the rollers are placed in front of the doctor blade, which can aggravate the pressure in front of the blade (increasing from 3500Pa to around 5500 Pa) if the rollers are incorrectly mounted in place and deflected.
The prior art does not give structural parameters of the device of the roller scraper, if the combination position of the roller scraper is unreasonable, side effects can be generated on the spreading process, the pressure in front of the scraper is increased, and the deformation of the fixed layer is increased.
Disclosure of Invention
The invention aims to solve the technical problem of providing an improved method and device for a roller scraper in a photo-cured ceramic 3D printing spreading material aiming at the defects of the prior art.
The technical scheme for solving the technical problems is as follows: an improved method of a roller doctor blade in a photo-cured ceramic 3D printing blanket, comprising:
s1, establishing a fluid domain geometric model of a roller scraper in the process of photocuring ceramic 3D printing spreading;
s2, obtaining technological parameters;
s3, setting a physical field, setting boundary conditions, dividing grids and setting a solver for the fluid domain geometric model according to the process parameters;
s4, modifying structural parameters of the roller scraper in the fluid domain geometric model for a plurality of times, and respectively calculating to obtain pressure values before a plurality of scrapers;
s5, determining structural parameters of the scraper corresponding to the pressure value before the minimum scraper according to the pressure values before the plurality of scrapers.
The technical scheme of the invention has the beneficial effects that: the proper position of the roller relative to the scraper is determined through analysis, the roller scraper device is optimized according to the actual working condition, the pressure before the scraper is reduced, the deformation of the solid is reduced, the manufacturing precision and the printing success rate of the printed part are improved, the research and development cost can be reduced, the research and development time is saved, and the research and development efficiency and the improvement efficiency of the roller scraper spreading device are improved. Theoretical guidance is provided for the structural design of the roller scraper, and the design process of the roller scraper device is simplified.
Further, the roll doctor blade structural parameters in the fluid domain geometric model are the lateral distance of the roll and doctor blade and the height between the roll and the solid.
The beneficial effects of adopting the further technical scheme are as follows: structural parameters of the roller scraper are optimally designed at multiple angles, and simulation accuracy is improved. The proper position of the roller relative to the scraper is determined through analysis, the roller scraper device is optimized according to the actual working condition, the pressure before the scraper is reduced, the deformation of the solid is reduced, the manufacturing precision and the printing success rate of the printed part are improved, the research and development cost can be reduced, the research and development time is saved, and the research and development efficiency and the improvement efficiency of the roller scraper spreading device are improved. Theoretical guidance is provided for the structural design of the roller scraper, and the design process of the roller scraper device is simplified.
Further, the process parameters are the inclination angle of the doctor blade, the straight face portion of the doctor blade, the horizontal moving speed of the doctor blade, the height of the doctor blade from the solid, the viscosity of the ceramic material, the material density of the ceramic material, the contact angle of the ceramic material, the surface tension of the ceramic material, and the initial roller doctor blade structure parameters.
The beneficial effects of adopting the further technical scheme are as follows: the specific data may be set according to manufacturing requirements and process requirements. The process parameters are set in multiple aspects, so that the simulation reliability is improved, and the accuracy is improved.
Further, the step of setting a physical field for the fluid domain geometric model includes: and setting a physical field for the fluid domain geometric model by adopting a phase field method, a laminar flow model method and a dynamic grid model method.
The beneficial effects of adopting the further technical scheme are as follows: and a phase field method, laminar flow and grid equipment are adopted to restore the spreading process of the ceramic photo-curing 3D printing, and the influence of slurry before a knife is considered in a simulation model. The simulation reliability and the accuracy are improved.
Further, the laminar flow mode method selects an N-S equation, and a phase field method is selected to set an air domain and a slurry domain in a physical field.
The beneficial effects of adopting the further technical scheme are as follows: the simulation reliability and the accuracy are improved.
Further, the step of setting a boundary condition for the fluid domain geometric model includes: the portion in contact with air was set as the open border, the doctor blade border was set as the moving grid border, and the roller border was set as the wall movement.
The beneficial effects of adopting the further technical scheme are as follows: boundary conditions are conveniently set for the fluid domain geometric model, simulation reliability is improved, and accuracy is improved.
Further, the fluid domain geometric model is automatically meshed according to a preset maximum mesh size, and the solver is a transient solver.
The beneficial effects of adopting the further technical scheme are as follows: the automation is improved, the simulation reliability is improved, and the accuracy is improved.
Further, step S3 includes:
s31, setting a physical field, setting boundary conditions, dividing grids and setting a solver for the fluid domain geometric model according to technological parameters to generate a calculation model;
s32, performing fluid simulation calculation on the calculation model to obtain a simulation result;
s33, judging whether the simulation result is converged or not;
and S34, when the simulation result is converged, executing the step S3.
The beneficial effects of adopting the further technical scheme are as follows: setting a fluid domain geometric model, judging whether a simulation result is converged, and carrying out subsequent steps when the simulation result is converged, so that the simulation reliability and the accuracy are improved.
Further, step S33 includes:
acquiring a preset tolerance error and an actual result;
calculating a relative error between the simulation result and the actual result;
judging whether the relative error is smaller than a preset tolerance error or not;
and when the relative error is smaller than the preset tolerance error, judging that the simulation result is converged.
The beneficial effects of adopting the further technical scheme are as follows: and selecting a transient solver to solve, judging to be converged when the final relative error is smaller than the allowable error, and recording the pressure value generated under the model.
In addition, the invention also provides an improved device of a roller scraper in the photo-cured ceramic 3D printing spreading, which comprises the following components: acquisition equipment and processing equipment, wherein the acquisition equipment is connected with the processing equipment,
the processing equipment is used for establishing a fluid domain geometric model of the roller scraper in the process of photocuring ceramic 3D printing spreading;
the acquisition equipment is used for acquiring the technological parameters;
the processing equipment is also used for setting a physical field, setting boundary conditions, dividing grids and setting a solver for the fluid domain geometric model according to the process parameters;
the processing equipment is also used for modifying the structural parameters of the roller scraper in the fluid domain geometric model for a plurality of times and calculating the structural parameters respectively to obtain pressure values before a plurality of scrapers;
the processing equipment is also used for determining the structural parameters of the roller scraper corresponding to the pressure value before the minimum scraper according to the pressure values before a plurality of scrapers.
The technical scheme of the invention has the beneficial effects that: the proper position of the roller relative to the scraper is determined through analysis, the roller scraper device is optimized according to the actual working condition, the pressure before the scraper is reduced, the deformation of the solid is reduced, the manufacturing precision and the printing success rate of the printed part are improved, the research and development cost can be reduced, the research and development time is saved, and the research and development efficiency and the improvement efficiency of the roller scraper spreading device are improved. Theoretical guidance is provided for the structural design of the roller scraper, and the design process of the roller scraper device is simplified.
Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
Fig. 1 is one of the schematic flow charts of the improved method of roll doctor blade in photo-cured ceramic 3D printing blanket provided by the embodiment of the invention.
Fig. 2 is a second schematic flow chart of an improved method of a roller doctor blade in a photo-cured ceramic 3D printing blanket according to an embodiment of the invention.
Fig. 3 is a schematic structural diagram of an improved device for a roller doctor blade in a photo-cured ceramic 3D printing blanket according to an embodiment of the present invention.
FIG. 4 is a graph showing one of the fluid volume profiles during a paving process according to an embodiment of the present invention.
FIG. 5 is a graph showing one of the pressure profiles during a paving process according to an embodiment of the present invention.
FIG. 6 is a graph showing two pressure distribution diagrams during a spreading process according to an embodiment of the present invention.
FIG. 7 is a graph showing two fluid volume distribution diagrams during a paving process according to an embodiment of the present invention.
Fig. 8 is a schematic diagram of a relative positional relationship of a roller doctor according to an embodiment of the present invention.
FIG. 9 is a third pressure profile during a paving process according to an embodiment of the present invention.
Reference numerals illustrate: 1. an acquisition device; 2. a processing device; 3. a scraper; 4. a slurry; 5. solid; 6. and (3) a roller.
Detailed Description
The principles and features of the present invention are described below with reference to the drawings, the examples are illustrated for the purpose of illustrating the invention and are not to be construed as limiting the scope of the invention.
As shown in fig. 1, an embodiment of the present invention provides an improved method for a roller doctor blade in a photo-cured ceramic 3D printing blanket, including:
s1, establishing a fluid domain geometric model of a roller scraper in the process of photocuring ceramic 3D printing spreading;
s2, obtaining technological parameters;
s3, setting a physical field, setting boundary conditions, dividing grids and setting a solver for the fluid domain geometric model according to the process parameters;
s4, modifying structural parameters of the roller scraper in the fluid domain geometric model for a plurality of times, and respectively calculating to obtain pressure values before a plurality of scrapers;
s5, determining structural parameters of the scraper corresponding to the pressure value before the minimum scraper according to the pressure values before the plurality of scrapers.
The technical scheme of the invention has the beneficial effects that: the proper position of the roller relative to the scraper is determined through analysis, the roller scraper device is optimized according to the actual working condition, the pressure before the scraper is reduced, the deformation of the solid is reduced, the manufacturing precision and the printing success rate of the printed part are improved, the research and development cost can be reduced, the research and development time is saved, and the research and development efficiency and the improvement efficiency of the roller scraper spreading device are improved. Theoretical guidance is provided for the structural design of the roller scraper, and the design process of the roller scraper device is simplified.
As shown in fig. 2, 1, establishing a geometric model of a ceramic photo-curing 3D printing pavement; 2. setting physical parameters, boundary conditions, dividing grids and setting a solver according to manufacturing requirements and process parameters; 3. changing the lateral distance between the roller and the scraper and the distance between the roller and the solidified layer (solidified) to recalculate the simulation model; 4. and acquiring a pressure value before the cutter, finding a rule, and determining a better structural parameter.
Further, the roll doctor blade structural parameters in the fluid domain geometric model are the lateral distance of the roll and doctor blade and the height between the roll and the solid.
The beneficial effects of adopting the further technical scheme are as follows: structural parameters of the roller scraper are optimally designed at multiple angles, and simulation accuracy is improved. The proper position of the roller relative to the scraper is determined through analysis, the roller scraper device is optimized according to the actual working condition, the pressure before the scraper is reduced, the deformation of the solid is reduced, the manufacturing precision and the printing success rate of the printed part are improved, the research and development cost can be reduced, the research and development time is saved, and the research and development efficiency and the improvement efficiency of the roller scraper spreading device are improved. Theoretical guidance is provided for the structural design of the roller scraper, and the design process of the roller scraper device is simplified.
Further, the process parameters are the inclination angle of the doctor blade, the straight face portion of the doctor blade, the horizontal moving speed of the doctor blade, the height of the doctor blade from the solid, the viscosity of the ceramic material, the material density of the ceramic material, the contact angle of the ceramic material, the surface tension of the ceramic material, and the initial roller doctor blade structure parameters.
The beneficial effects of adopting the further technical scheme are as follows: the specific data may be set according to manufacturing requirements and process requirements. The process parameters are set in multiple aspects, so that the simulation reliability is improved, and the accuracy is improved.
Further, the step of setting a physical field for the fluid domain geometric model includes: and setting a physical field for the fluid domain geometric model by adopting a phase field method, a laminar flow model method and a dynamic grid model method.
The beneficial effects of adopting the further technical scheme are as follows: and a phase field method, laminar flow and grid equipment are adopted to restore the spreading process of the ceramic photo-curing 3D printing, and the influence of slurry before a knife is considered in a simulation model. The simulation reliability and the accuracy are improved.
Further, the laminar flow mode method selects an N-S equation, and a phase field method is selected to set an air domain and a slurry domain in a physical field.
The beneficial effects of adopting the further technical scheme are as follows: the simulation reliability and the accuracy are improved.
Further, the step of setting a boundary condition for the fluid domain geometric model includes: the portion in contact with air was set as the open border, the doctor blade border was set as the moving grid border, and the roller border was set as the wall movement.
The beneficial effects of adopting the further technical scheme are as follows: boundary conditions are conveniently set for the fluid domain geometric model, simulation reliability is improved, and accuracy is improved.
Further, the fluid domain geometric model is automatically meshed according to a preset maximum mesh size, and the solver is a transient solver.
The beneficial effects of adopting the further technical scheme are as follows: the automation is improved, the simulation reliability is improved, and the accuracy is improved.
Further, step S3 includes:
s31, setting a physical field, setting boundary conditions, dividing grids and setting a solver for the fluid domain geometric model according to technological parameters to generate a calculation model;
s32, performing fluid simulation calculation on the calculation model to obtain a simulation result;
s33, judging whether the simulation result is converged or not;
and S34, when the simulation result is converged, executing the step S3.
The beneficial effects of adopting the further technical scheme are as follows: setting a fluid domain geometric model, judging whether a simulation result is converged, and carrying out subsequent steps when the simulation result is converged, so that the simulation reliability and the accuracy are improved.
Further, step S33 includes:
acquiring a preset tolerance error and an actual result;
calculating a relative error between the simulation result and the actual result;
judging whether the relative error is smaller than a preset tolerance error or not;
and when the relative error is smaller than the preset tolerance error, judging that the simulation result is converged.
The beneficial effects of adopting the further technical scheme are as follows: and selecting a transient solver to solve, judging to be converged when the final relative error is smaller than the allowable error, and recording the pressure value generated under the model.
The method can be used for analyzing and determining the proper position, rotating speed and other parameters of the roller relative to the scraper, providing theoretical guidance for the structural design of the roller scraper and simplifying the design process of the roller scraper device. The photocuring spreading is completed only by using the roller and the scraper, so that the pressure before the cutter can be reduced, the deformation of the solid is reduced, and the printing success rate is improved.
The invention provides an improvement method of a roller scraper in a photo-cured ceramic 3D printing spreading material, which can be an improvement method of a roller scraper device in a photo-cured ceramic 3D printing spreading material based on CFD (computational fluid dynamics ) technology, and comprises the following steps: a first step of: establishing a fluid domain geometric model of the roller scraper in the spreading process; and a second step of: setting boundary conditions and physical fields according to the actually measured material data and cutter data, dividing grids, selecting a solver to perform fluid simulation calculation on the established calculation model, entering simulation analysis, and judging convergence of simulation results; and a third step of: changing geometric parameters or technological parameters in the model, mainly representing changing the transverse distance between the rollers of the roller scraper and the height between the rollers and the solid, repeatedly performing simulation calculation and analysis, and calculating the pressure data result of the target point; fourth step: based on the data, the structural parameters at which the compressive force is minimal, including the lateral distance of the roller from the doctor blade, the height between the roller and the solid, are taken.
It should be noted that, instead of the parameters: the simulation of the embodiment of the invention optimizes the distance between the roller and the scraper and the distance between the roller and the fixed layer under the condition that other process and manufacturing parameters are not changed, and the parameters such as the rotating speed of the roller, the diameter of the roller and the like can be optimized.
Specifically, 1. A geometric model of a roller scraper spreading process in ceramic photo-curing 3D printing spreading can be established by adopting SolidWorks software, and Comsol (COMSOL Multiphysics, multiple physical fields simulation software) is introduced for analysis.
It should be noted that, the software angle: solidworks can be replaced with any three-dimensional/two-dimensional software, and Comsol simulation software can be replaced with any other software capable of simulating a fluid. The meshing can also be performed in specialized meshing software without the Comsol's own meshing function.
2. The speed, size and material of the selected scraper in the actual spreading process are measured, and the geometric model of the material is modified, boundary conditions and physical fields are set. Parameters for the following experiments are for example: the scraper 3 is a power law model of a beveled straight surface knife (the dip angle is 75 degrees, the straight surface part is 0.4mm, the horizontal moving speed is 20mm/s, the height of the scraper from the solid is 0.5 mm), and the high-viscosity ceramic material (slurry 4) has the shearing rate of 20s -1 At a viscosity of 30 pa.s, a material density of 2740kg/m 3 The contact angle was 60 °, the surface tension was 0.03N/m, the diameter of the roller 6 was 7mm, the doctor blade-roller gap was 7mm initially, and the height of the roller 6 from the solid 5 was 1.5mm. In practical applications, specific data may be set according to manufacturing requirements and process requirements.
3. The physical field is selected from a phase field method, laminar flow and a movable grid, the laminar flow mode method is selected from an N-S equation (Navier-Stokes ), the physical field comprises gravity, an air domain and a slurry domain are set in the phase field method, the thickness parameter of an interface is 0.1mm, and the mobility adjustment parameter is 1.
4. In the boundary condition, the portion in contact with air is selected as an open boundary. The doctor blade boundary was set as a moving grid boundary, the set speed was 20mm/s horizontal, the roller boundary was set as wall movement, the speed was set at 20mm/s, and the bottom direction rotational speed was opposite to the doctor blade direction.
5. The maximum grid size of the grid design is 0.2mm, and the automatic grid dividing function is started.
6. And selecting a transient solver to solve, and judging that the relative error is converged when the final relative error is smaller than the allowable error.
7. The pressure values generated under this model were recorded.
8. As shown in fig. 7 and 8, the geometric model was modified, including the lateral distance of the roller from the doctor blade (7 mm, 6mm, 5mm, 4mm, no roller), the height between the roller and the solid (1.5 mm, 0.5mm, no roller), and the above steps were repeated, and the parameter with the smallest pressure value was selected.
Wherein the arrow in fig. 7 represents the rotational direction of the roller, the doctor blade may have an inclination of 75 degrees.
The following results were obtained,
table 1:
the correctness of the model can be checked by the experiment number 9, and the model is tested in a laboratory without a roller.
From the above results, it is clear that when the roller height is 1.5mm, the lateral distance is less than about 6mm, the roller will have an "extrusion effect" on the blade edge, i.e. the lateral distance between the roller and the doctor blade cannot be too close, otherwise the extrusion phenomenon is obvious, the pressure before the doctor blade will be increased, and if the distance is slightly far, the roller is independent, and cannot affect the pressure at the front end of the doctor blade.
Under the condition that the height of the roller is 1.5mm, the transverse distance is less than about 5mm, the roller has an extrusion effect on the knife edge, under the condition that the height of the roller is 0.5mm, the transverse distance is less than about 4mm, the roller has an extrusion effect on the knife edge, namely the height of the roller cannot be too high, otherwise, the roller cannot have a depressurization effect.
As shown in fig. 9, fig. 9 shows the pressure distribution where the doctor blade is 6mm from the roll and the roll is 0.5mm from the cured layer, the direction of the lay-up is to the right, and the circle in the figure is the pressure area.
In summary, under the condition that other process parameters are certain, as shown in the data of experiment number 4 in table 1, the mechanism parameter that the distance between the scraper and the roller is 6mm and the distance between the roller and the solidified layer is 0.5mm is most suitable. The pressure at the front end of the scraper can be reduced from 3500Pa to 791Pa, and the pressure is reduced by 77.4%.
1. As described above, according to the calculated pre-blade pressure by simulation, the relative position and size relationship of the improved roller blade 3 is obtained, the spreading effect of the roller blade is greatly improved, the deformation of the solidified layer is reduced, and based on the specific case, the optimized roller blade can reduce the pre-blade pressure by 77.4%.
2. And the CFD technology is based, so that the improved design period is greatly shortened, the design cost and the experimental cost are reduced, and the pressure distribution before the cutter is effectively improved on the basis of not greatly changing the structure of the device.
3. In addition, the CFD technology can be adopted to model the spreading process of ceramic photocuring 3D printing, the simulation calculation result and the measured data error are controlled within 20% when no roller exists, and the rationality of the model is verified.
In a word, the invention optimizes the parameter values of each size of the roller scraper, and has the advantages of small structural change, easy implementation and the like.
The method of optimizing a roller doctor apparatus using CFD technology was analyzed from a quantitative point of view. And a phase field method, laminar flow and grid equipment are adopted to restore the spreading process of the ceramic photo-curing 3D printing, and the influence of slurry before a knife is considered in a simulation model. The CFD is used for guiding the design of the spreading device for ceramic photocuring 3D printing, so that the debugging and experiment time is reduced conveniently and rapidly.
As shown in fig. 3, the present invention further provides an improved apparatus for a roll doctor blade in a photo-cured ceramic 3D printing blanket, comprising: an acquisition device 1 and a processing device 2, said acquisition device 1 being connected to said processing device 2,
the processing equipment is used for establishing a fluid domain geometric model of the roller scraper in the process of photocuring ceramic 3D printing spreading;
the acquisition equipment is used for acquiring the technological parameters;
the processing equipment is also used for setting a physical field, setting boundary conditions, dividing grids and setting a solver for the fluid domain geometric model according to the process parameters;
the processing equipment is also used for modifying the structural parameters of the roller scraper in the fluid domain geometric model for a plurality of times and calculating the structural parameters respectively to obtain pressure values before a plurality of scrapers;
the processing equipment is also used for determining the structural parameters of the roller scraper corresponding to the pressure value before the minimum scraper according to the pressure values before a plurality of scrapers.
The technical scheme of the invention has the beneficial effects that: the proper position of the roller relative to the scraper is determined through analysis, the roller scraper device is optimized according to the actual working condition, the pressure before the scraper is reduced, the deformation of the solid is reduced, the manufacturing precision and the printing success rate of the printed part are improved, the research and development cost can be reduced, the research and development time is saved, and the research and development efficiency and the improvement efficiency of the roller scraper spreading device are improved. Theoretical guidance is provided for the structural design of the roller scraper, and the design process of the roller scraper device is simplified.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. An improved method of a roller doctor blade in a photo-cured ceramic 3D printing blanket, comprising:
s1, establishing a fluid domain geometric model of a roller scraper in the process of photocuring ceramic 3D printing spreading;
s2, obtaining technological parameters;
s3, setting a physical field, setting boundary conditions, dividing grids and setting a solver for the fluid domain geometric model according to the process parameters;
s4, modifying structural parameters of the roller scraper in the fluid domain geometric model for a plurality of times, and respectively calculating to obtain pressure values before a plurality of scrapers;
s5, determining structural parameters of the scraper corresponding to the pressure value before the minimum scraper according to the pressure values before the plurality of scrapers.
2. An improved method of roll doctor blades in photo-cured ceramic 3D printing pavements in accordance with claim 1 wherein the roll doctor blade structural parameters in the fluid domain geometric model are the lateral distance of the roll and doctor blade and the height between the roll and the solid body.
3. The method of claim 1, wherein the process parameters are blade inclination, blade straight section, blade horizontal movement speed, blade height from solid, viscosity of ceramic material, material density of ceramic material, contact angle of ceramic material, surface tension of ceramic material, initial roller blade structure parameters.
4. The improved method of roll doctor blades in photo-cured ceramic 3D printing paste as claimed in claim 1, wherein the step of setting a physical field for the fluid domain geometric model is: and setting a physical field for the fluid domain geometric model by adopting a phase field method, a laminar flow model method and a dynamic grid model method.
5. The improved method of a roller doctor blade in a 3D printing blanket of photo-cured ceramic according to claim 4, wherein the laminar flow modeling method is an N-S equation, and the phase field method is used for setting the air field and the slurry field in the physical field.
6. The method of claim 1, wherein the step of setting boundary conditions for the fluid domain geometric model is: the portion in contact with air was set as the open border, the doctor blade border was set as the moving grid border, and the roller border was set as the wall movement.
7. The improved method of roller blades in photo-cured ceramic 3D printing paste according to claim 1, wherein the fluid domain geometric model is automatically gridded according to a preset maximum grid size, and the solver is a transient solver.
8. The improved method of roll doctor blades in photo-cured ceramic 3D printing paste as claimed in claim 1, wherein step S3 includes:
s31, setting a physical field, setting boundary conditions, dividing grids and setting a solver for the fluid domain geometric model according to technological parameters to generate a calculation model;
s32, performing fluid simulation calculation on the calculation model to obtain a simulation result;
s33, judging whether the simulation result is converged or not;
and S34, when the simulation result is converged, executing the step S4.
9. The method of improving a roll doctor blade in a photo-cured ceramic 3D printing paste as claimed in claim 8, wherein step S33 includes:
acquiring a preset tolerance error and an actual result;
calculating a relative error between the simulation result and the actual result;
judging whether the relative error is smaller than a preset tolerance error or not;
and when the relative error is smaller than the preset tolerance error, judging that the simulation result is converged.
10. An improved apparatus for a roller doctor blade in a photo-cured ceramic 3D printing blanket, comprising: the device comprises acquisition equipment and processing equipment, wherein the acquisition equipment is connected with the processing equipment, and the processing equipment is used for establishing a fluid domain geometric model of a roller scraper in the process of photocuring ceramic 3D printing spreading;
the acquisition equipment is used for acquiring the technological parameters;
the processing equipment is also used for setting a physical field, setting boundary conditions, dividing grids and setting a solver for the fluid domain geometric model according to the process parameters;
the processing equipment is also used for modifying the structural parameters of the roller scraper in the fluid domain geometric model for a plurality of times and calculating the structural parameters respectively to obtain pressure values before a plurality of scrapers;
the processing equipment is also used for determining the structural parameters of the roller scraper corresponding to the pressure value before the minimum scraper according to the pressure values before a plurality of scrapers.
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