A method for determining DLP ceramic photocuring 3D printing parameters

Abstract

This invention discloses a method for determining parameters in DLP ceramic photopolymerization 3D printing, specifically including the following steps: S2, adding ceramic slurry; S3, exposure; S4, cleaning and measurement; S5, obtaining the average thickness of the cured ceramic slurry layer; S6, measuring the hole size and gap width; S7, creating a table; S8, analyzing the parts to be printed; S9, measuring the range of slurry liquid film thickness after material laying; and S1, adjusting the squeegee height. This invention relates to the field of additive manufacturing technology for ceramic materials. This method for determining parameters in DLP ceramic photopolymerization 3D printing obtains the cured thickness of a specific ceramic slurry corresponding to ultraviolet light irradiation power P and irradiation time t through repeated experiments. A printing standard part is designed, and the range of slurry planar forming accuracy is obtained by observing the printed standard part. Simultaneously, the distance between the squeegee and the printing bottom surface is adjusted by repeatedly measuring the thickness of the slurry laid during the material laying process to determine the squeegee height corresponding to the required cured thickness.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology for ceramic materials, specifically a method for determining parameters in DLP ceramic photopolymerization 3D printing. Background Technology

[0002] DLP (Digital Photopolymerization) additive manufacturing technology is a relatively mature 3D printing technology. Its principle involves first slicing the desired 3D object into two-dimensional layers, then projecting ultraviolet light as a surface beam onto a slurry mixed with photosensitive resin using DLP. This causes the layer to solidify and adhere to the pre-formed portion or platform, ultimately achieving additive manufacturing to obtain the desired 3D object. Due to its advantages such as high printing precision and high design freedom, it has applications in precision casting and aerospace manufacturing.

[0003] In practical ceramic DLP photopolymer additive manufacturing, to achieve better printing results, numerous repeated experiments are often required when changing ceramic pastes or printing equipment to find the optimal process parameters. However, excessive repetitive experiments waste time and effort and increase costs. Existing research shows that in DLP photopolymer additive manufacturing, the exposure intensity and time of ultraviolet light, the forming accuracy of the paste, and the squeegee height all have a significant impact on the forming quality of the printed parts. Therefore, finding a suitable method to determine the relevant parameters in DLP ceramic printing is of practical significance.

[0004] The prior art is disclosed in Chinese Patent Publication No. CN110142959A, which describes a method for rapidly determining the exposure time parameters of DLP photosensitive resin 3D printing. This method uses a test block obtained through image processing to determine the single-layer exposure time corresponding to the optimal printing size error.

[0005] The drawback of the prior art is that while it achieves rapid determination of the single-layer exposure time corresponding to the highest printing accuracy, it does not involve the adjustment of the cured layer thickness and the squeegee height. Furthermore, the invention mainly studies the printing process of liquid photosensitive resin and does not consider the influence of different ceramic powders on the curing process and accuracy in ceramic photocuring printing.

[0006] The second prior art, disclosed in Chinese Patent Publication No. CN110370625A, is a method for improving the efficiency of DLP photopolymer additive manufacturing. This method first obtains the forming property parameters of the printing material by printing a standard part. Then, through repeated printing experiments, it obtains the parameter B related to the forming properties of the material at different concentrations of ultraviolet absorber cd and the value of the time tT required for the material to absorb energy when reaching the critical curing state. A relationship between tT, B, and cd is established. Based on this relationship, the values ​​of the relevant parameter B and time tT can be obtained to eliminate repeated changes in the energy state of the slurry and improve printing efficiency.

[0007] The drawback of the second prior art is that while the method optimizes the photopolymerization printing process and improves the printing speed by establishing a relational formula to obtain printing parameters, it does not consider the forming accuracy problem caused by the scattering of ultraviolet light in the slurry. Summary of the Invention

[0008] (a) Technical problems to be solved

[0009] To address the shortcomings of existing technologies, this invention provides a method for determining parameters in DLP ceramic photopolymerization 3D printing. This method addresses the lack of a comprehensive and widely applicable method for determining process parameters in photopolymerization 3D printing. Specifically, it provides a method for determining the ultraviolet light exposure intensity and time, the planar forming accuracy of ceramic slurry, and the squeegee height in DLP ceramic printing.

[0010] (II) Technical Solution

[0011] To achieve the above objectives, the present invention provides the following technical solution: a method for determining parameters in DLP ceramic photopolymerization 3D printing, specifically comprising the following steps:

[0012] S1. Select a dry and clean glass slide and drop a drop of ceramic paste to be printed onto it;

[0013] S2. Place the glass slide with the slurry dripped in step S1 above the DLP light source, import the exposure pattern, and expose it with specific parameters. A thin layer of ceramic green body with the pattern will grow on the glass slide.

[0014] S3. Clean the glass slide that has been exposed in step S2 with a cleaning agent, wipe it clean with a soft cloth, and let it dry before measuring its thickness and dimensions.

[0015] S4. Place the dried glass sheet from step S3 onto a thickness gauge, measure the thickness of different zones of the cured layer, and repeat the operation by changing the point to obtain the average thickness of the ceramic slurry cured layer.

[0016] S5. Use a microscope to measure the hole size and gap width on the cured sheet, and compare them with the design model to calculate the error;

[0017] S6. Repeat steps S1-S5 above to obtain the average cured thickness of ceramic slurry corresponding to different exposure power and exposure time, and establish a table to obtain the exposure power and time parameters corresponding to different cured layer thickness, gap size and hole size.

[0018] S7. Analyze the parts to be printed and select printing parameters according to the dimensional accuracy requirements;

[0019] S8. Pour the ceramic slurry into the equipment, perform the spreading operation, and measure the slurry liquid film thickness range after spreading multiple times using a wet film comb.

[0020] S9. Adjust the squeegee height according to the liquid film thickness obtained in step S8, and repeat the material laying and measurement process to finally obtain the squeegee height corresponding to the material laying thickness suitable for printing.

[0021] Preferably, in step S1, the thickness of the glass sheet does not exceed 0.2 mm, and the ceramic slurry needs to cover the area of ​​the exposed pattern and the slurry thickness is not less than 0.5 mm.

[0022] Preferably, in step S2, the slurry needs to cover the area of ​​the exposure pattern, the exposure parameters are set to the selected power density, and the exposure time is calculated in seconds.

[0023] Preferably, the cleaning agent in step S3 is alcohol or isopropanol.

[0024] Preferably, the exposed pattern in step S2 is a standard part pattern, which is designed to be divided into three areas: area A, area B, and area C. Area A is a narrow slit area, indicating the printing accuracy of the minimum thin-wall gap.

[0025] Preferably, area B is a small hole area, indicating the printing precision of the smallest hole.

[0026] Preferably, area C is a fence area used to detect the effect of gaps of different widths on the curing thickness, wherein a point is measured every 5mm from top to bottom in area C.

[0027] Preferably, in step S7, the curing thickness is selected as 25-50um per layer. The minimum formable structure size is determined by the gap width and the hole size. Based on this, appropriate printing parameters are selected. The optimal printing parameters are selected when the curing thickness is 1.5-4 times the slice thickness, corresponding to the exposure power and time, while ensuring that the diameter of the smallest hole that can be formed is minimized.

[0028] Preferably, in step S7, alcohol is used to clean the standard part.

[0029] Preferably, the thickness of the spreading material in step S9 is 50-300um, and the specific value is determined by the thickness of the slice and the viscosity of the slurry. It is selected to be 2-6 times the thickness of the slice, and the thicker the slurry, the smaller the spreading material thickness is selected.

[0030] (III) Beneficial Effects

[0031] This invention provides a method for determining parameters in DLP ceramic photopolymerization 3D printing. Compared with existing technologies, it has the following advantages: The method for determining parameters in DLP ceramic photopolymerization 3D printing specifically includes the following steps: S1, Select a dry and clean glass slide and drop a drop of ceramic slurry to be printed onto it; S2, Place the glass slide with slurry from step S1 above a DLP light source, import the exposure pattern, and expose it with specific parameters. A thin layer of ceramic green body with a pattern will grow on the glass slide; S3, Clean the glass slide after exposure in step S2 with a cleaning agent, wipe it clean with a soft cloth, and dry it before measuring its thickness and dimensions; S4, Place the dried glass slide from step S3 on a thickness gauge, measure the thickness of different zones of the cured layer, and repeat the operation at different points to obtain the average thickness of the ceramic slurry cured layer; S5, Measure the hole size and gap width on the cured sheet using a microscope and compare it with the design model to calculate the error; S6, Repeat the above steps S1-S5 to obtain different exposure... The average cured thickness of the ceramic slurry corresponding to the light power and exposure time is calculated, and a table is established to obtain the exposure power and time parameters corresponding to different cured layer thicknesses, gap sizes, and hole sizes; S7, the parts to be printed are analyzed, and printing parameters are selected according to the dimensional accuracy requirements; S8, the ceramic slurry is poured into the equipment, the material spreading operation is performed, and the range of slurry liquid film thickness after spreading is obtained by multiple measurements through a wet film comb; S9, the squeegee height is adjusted according to the liquid film thickness obtained in step S8, and the spreading and measurement process is repeated to finally obtain the squeegee height corresponding to the suitable spreading thickness for printing. The curing thickness of a specific ceramic slurry corresponding to ultraviolet light irradiation power P and irradiation time t is obtained through repeated experiments. A printing standard part is designed, and the range of slurry planar forming accuracy is obtained by observing the printed standard part. At the same time, the distance between the squeegee and the printing bottom surface is adjusted by repeatedly measuring the slurry thickness during the spreading process to determine the squeegee height corresponding to the required curing thickness. Attached Figure Description

[0032] Figure 1 This is a diagram of the ceramic additive manufacturing apparatus of the present invention;

[0033] Figure 2 This is a schematic diagram of the standard part printed according to the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Please see Figure 1-2 The present invention provides three technical solutions: a method for determining parameters of DLP ceramic photopolymerization 3D printing, specifically including the following embodiments:

[0036] Example 1

[0037] A method for determining parameters in DLP ceramic photopolymerization 3D printing specifically includes the following steps:

[0038] S1. Select a dry and clean glass slide, and drop a drop of ceramic paste to be printed on it. The thickness of the glass slide is 0.2mm. The ceramic paste should cover the area of ​​the exposed pattern and the paste thickness should be 0.5mm.

[0039] S2. Place the glass slide with the slurry dripped in step S1 above the DLP light source, and introduce the slurry as shown in the image. Figure 2 The exposure pattern shown is exposed with specific parameters. A thin layer of ceramic green body with the pattern will grow on the glass slide. The slurry needs to cover the area of ​​the exposure pattern. The exposure parameters are set to the selected power density and the exposure time is calculated in seconds. The exposure pattern is the standard part pattern. Its design is divided into three areas: area A, area B and area C. Area A is the narrow slit area, indicating the printing accuracy of the minimum thin-wall gap. Area B is the small hole area, indicating the printing accuracy of the minimum hole. Area C is the fence area, used to detect the effect of different slit widths on the curing thickness.

[0040] S3. Clean the glass slide that has been exposed in step S2 with a cleaning agent, wipe it clean with a soft cloth, and let it dry before measuring its thickness and size. Alcohol or isopropanol can be used as the cleaning agent.

[0041] S4. Place the dried glass sheet from step S3 onto a thickness gauge to measure the thickness of different zones of the cured layer. Repeat the operation by changing the measurement points to obtain the average thickness of the ceramic slurry cured layer. In zone C, a measurement point is taken every 5 mm from top to bottom.

[0042] S5. Use a microscope to measure the hole size and gap width on the cured sheet, and compare them with the design model to calculate the error;

[0043] S6. Repeat steps S1-S5 above to obtain the average cured thickness of ceramic slurry corresponding to different exposure power and exposure time, and establish a table to obtain the exposure power and time parameters corresponding to different cured layer thickness, gap size and hole size.

[0044] S7. Analyze the parts to be printed, select printing parameters according to the dimensional accuracy requirements, select a curing thickness of 35um per layer, the minimum formable structure size is determined by the gap width and hole size, and select appropriate printing parameters accordingly. Select the exposure power and time corresponding to a curing thickness of 2.8 times the slice thickness, and at the same time ensure that the diameter of the smallest hole that can be formed is the smallest, which is the best printing parameter. Clean the standard parts with alcohol.

[0045] S8. Pour the ceramic slurry into the equipment, perform the spreading operation, and measure the slurry liquid film thickness range after spreading multiple times using a wet film comb.

[0046] S9. Adjust the height of the scraper according to the liquid film thickness obtained in step S8, and repeat the spreading and measurement. The spreading thickness is 180um. The specific value is determined by the slice thickness and the viscosity of the slurry. Select 4 times the slice thickness. The more viscous the slurry, the smaller the spreading thickness should be.

[0047] Example 2

[0048] A method for determining parameters in DLP ceramic photopolymerization 3D printing specifically includes the following steps:

[0049] S1. Select a dry and clean glass slide, and drop a drop of ceramic paste to be printed on it. The thickness of the glass slide is 0.1mm, and the ceramic paste should cover the area of ​​the exposed pattern and be 0.6mm thick.

[0050] S2. Place the glass slide with the slurry dripped in step S1 above the DLP light source, and introduce the slurry as shown in the image. Figure 2 The exposure pattern shown is exposed with specific parameters. A thin layer of ceramic green body with the pattern will grow on the glass slide. The slurry needs to cover the area of ​​the exposure pattern. The exposure parameters are set to the selected power density and the exposure time is calculated in seconds. The exposure pattern is the standard part pattern. Its design is divided into three areas: area A, area B and area C. Area A is the narrow slit area, indicating the printing accuracy of the minimum thin-wall gap. Area B is the small hole area, indicating the printing accuracy of the minimum hole. Area C is the fence area, used to detect the effect of different slit widths on the curing thickness.

[0051] S3. Clean the glass slide that has been exposed in step S2 with a cleaning agent, wipe it clean with a soft cloth, and let it dry before measuring its thickness and size. Alcohol or isopropanol can be used as the cleaning agent.

[0052] S4. Place the dried glass sheet from step S3 onto a thickness gauge to measure the thickness of different zones of the cured layer. Repeat the operation by changing the measurement points to obtain the average thickness of the ceramic slurry cured layer. In zone C, a measurement point is taken every 5 mm from top to bottom.

[0053] S5. Use a microscope to measure the hole size and gap width on the cured sheet, and compare them with the design model to calculate the error;

[0054] S6. Repeat steps S1-S5 above to obtain the average cured thickness of ceramic slurry corresponding to different exposure power and exposure time, and establish a table to obtain the exposure power and time parameters corresponding to different cured layer thickness, gap size and hole size.

[0055] S7. Analyze the parts to be printed, select printing parameters according to the dimensional accuracy requirements, select a curing thickness of 25um per layer, the minimum formable structure size is determined by the gap width and hole size, and select appropriate printing parameters accordingly. Select the corresponding exposure power and time with a curing thickness of 1.5 times the slice thickness, and at the same time ensure that the diameter of the smallest hole that can be formed is the smallest, which is the best printing parameter. Clean the standard parts with alcohol.

[0056] S8. Pour the ceramic slurry into the equipment, perform the spreading operation, and measure the slurry liquid film thickness range after spreading multiple times using a wet film comb.

[0057] S9. Adjust the height of the scraper according to the liquid film thickness obtained in step S8, and repeat the spreading and measurement. The spreading thickness is 50um. The specific value is determined by the slice thickness and the viscosity of the slurry. Select twice the slice thickness. The more viscous the slurry, the smaller the spreading thickness should be.

[0058] Example 3

[0059] A method for determining parameters in DLP ceramic photopolymerization 3D printing specifically includes the following steps:

[0060] S1. Select a dry and clean glass slide, and drop a drop of ceramic paste to be printed on it. The thickness of the glass slide is 0.15mm. The ceramic paste should cover the area of ​​the exposed pattern and the paste thickness should be 0.7mm.

[0061] S2. Place the glass slide with the slurry dripped in step S1 above the DLP light source, and introduce the slurry as shown in the image. Figure 2The exposure pattern shown is exposed with specific parameters. A thin layer of ceramic green body with the pattern will grow on the glass slide. The slurry needs to cover the area of ​​the exposure pattern. The exposure parameters are set to the selected power density and the exposure time is calculated in seconds. The exposure pattern is the standard part pattern. Its design is divided into three areas: area A, area B and area C. Area A is the narrow slit area, indicating the printing accuracy of the minimum thin-wall gap. Area B is the small hole area, indicating the printing accuracy of the minimum hole. Area C is the fence area, used to detect the effect of different slit widths on the curing thickness.

[0062] S3. Clean the glass slide that has been exposed in step S2 with a cleaning agent, wipe it clean with a soft cloth, and let it dry before measuring its thickness and size. Alcohol or isopropanol can be used as the cleaning agent.

[0063] S4. Place the dried glass sheet from step S3 onto a thickness gauge to measure the thickness of different zones of the cured layer. Repeat the operation by changing the measurement points to obtain the average thickness of the ceramic slurry cured layer. In zone C, a measurement point is taken every 5 mm from top to bottom.

[0064] S5. Use a microscope to measure the hole size and gap width on the cured sheet, and compare them with the design model to calculate the error;

[0065] S6. Repeat steps S1-S5 above to obtain the average cured thickness of ceramic slurry corresponding to different exposure power and exposure time, and establish a table to obtain the exposure power and time parameters corresponding to different cured layer thickness, gap size and hole size.

[0066] S7. Analyze the parts to be printed, select printing parameters according to the dimensional accuracy requirements, select a curing thickness of 50um per layer, and the minimum formable structure size is determined by the gap width and hole size. Select appropriate printing parameters accordingly, choose the exposure power and time corresponding to a curing thickness of 4 times the slice thickness, and at the same time ensure that the diameter of the smallest hole that can be formed is the smallest. Then the best printing parameters are selected. Clean the standard parts with alcohol.

[0067] S8. Pour the ceramic slurry into the equipment, perform the spreading operation, and measure the slurry liquid film thickness range after spreading multiple times using a wet film comb.

[0068] S9. Adjust the height of the scraper according to the liquid film thickness obtained in step S8, and repeat the spreading and measurement. The spreading thickness is 300um. The specific value is determined by the slice thickness and the viscosity of the slurry. Select 6 times the slice thickness. The more viscous the slurry, the smaller the spreading thickness should be.

[0069] In summary, this invention obtains the curing thickness of a specific ceramic slurry corresponding to ultraviolet light irradiation power P and irradiation time t through repeated experiments, designs a printing standard part, and obtains the range of slurry planar forming accuracy by observing the printed standard part. At the same time, the distance between the scraper and the printing bottom surface is adjusted by repeatedly measuring the thickness of the slurry laid during the material spreading process, and the scraper height corresponding to the required curing thickness is determined.

[0070] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0071] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for determining parameters in DLP ceramic photopolymerization 3D printing, characterized in that: Specifically, the following steps are included: S1. Select a dry and clean glass slide and drop a drop of ceramic paste to be printed onto it; S2. Place the glass slide with the slurry dripped in step S1 above the DLP light source, import the exposure pattern, and expose it with specific parameters. A thin layer of ceramic green body with the pattern will grow on the glass slide. S3. Clean the glass slide that has been exposed in step S2 with a cleaning agent, wipe it clean with a soft cloth, and let it dry before measuring its thickness and dimensions. S4. Place the dried glass sheet from step S3 onto a thickness gauge, measure the thickness of different zones of the cured layer, and repeat the operation by changing the point to obtain the average thickness of the ceramic slurry cured layer. S5. Use a microscope to measure the hole size and gap width on the cured sheet, and compare them with the design model to calculate the error; S6. Repeat steps S1-S5 above to obtain the average cured thickness of ceramic slurry corresponding to different exposure power and exposure time, and establish a table to obtain the exposure power and time parameters corresponding to different cured layer thickness, gap size and hole size. S7. Analyze the parts to be printed and select printing parameters according to the dimensional accuracy requirements; S8. Pour the ceramic slurry into the equipment, perform the spreading operation, and measure the slurry film thickness range after spreading multiple times using a wet film comb. S9. Adjust the squeegee height according to the liquid film thickness obtained in step S8, and repeat the material laying and measurement process to finally obtain the squeegee height corresponding to the material laying thickness suitable for printing. In step S1, the thickness of the glass sheet shall not exceed 0.2 mm, and the ceramic slurry shall cover the area of ​​the exposed pattern and the slurry thickness shall not be less than 0.5 mm. In step S2, the slurry needs to cover the area of ​​the exposure pattern. The exposure parameters are set to the selected power density, and the exposure time is calculated in seconds. The exposure pattern in step S2 is the standard part pattern, which is designed to be divided into three areas: area A, area B, and area C. Area A is the narrow slit area, indicating the printing accuracy of the minimum thin-wall gap. Area B is the small hole area, indicating the printing accuracy of the minimum hole. The cleaning agent used in step S3 is either alcohol or isopropanol.

2. The method for determining parameters of DLP ceramic photopolymerization 3D printing according to claim 1, characterized in that: The C area is a fence area used to detect the effect of gaps of different widths on the curing thickness. In the C area, a point is measured every 5mm from top to bottom.

3. The method for determining parameters of DLP ceramic photopolymerization 3D printing according to claim 1, characterized in that: In step S7, the curing thickness is selected as 25-50um per layer. The minimum formable structure size is determined by the gap width and the hole size. Therefore, appropriate printing parameters are selected. The optimal printing parameters are the exposure power and time corresponding to a curing thickness of 1.5-4 times the slice thickness, while ensuring that the diameter of the smallest hole can be formed.

4. The method for determining parameters of DLP ceramic photopolymerization 3D printing according to claim 1, characterized in that: In step S7, alcohol is used to clean the standard parts.

5. The method for determining parameters of DLP ceramic photopolymerization 3D printing according to claim 1, characterized in that: In step S9, the thickness of the spread material is 50-300um. The specific value is determined by the thickness of the slice and the viscosity of the slurry. The thickness of the spread material is selected to be 2-6 times that of the slice. The more viscous the slurry, the smaller the thickness of the spread material should be.

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