Method of manufacturing dental objects
The method addresses the challenge of drying inorganic-filled carrier liquids by monitoring and controlling the drying process through temperature profiling and air flow management, ensuring high-quality and crack-free 3D printing.
Patent Information
- Application Number
- JP2025096137
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-06-10
- Filing Date
- 2025-06-09
- Publication Date
- 2025-12-22
AI Technical Summary
Drying or evaporating inorganic-filled carrier liquids based on polar or non-polar solvents in 3D printing is difficult and time-consuming, and reliable monitoring of the drying process is lacking, leading to potential mechanical solidification and cracking of printed layers.
A method involving the detection of a temperature profile during solvent evaporation, with controlled air flow and temperature management, allowing precise monitoring and control of the drying process.
Enables efficient and crack-free drying of printing layers, ensuring high-quality 3D printing by determining the optimal time for applying subsequent layers based on detected temperature profiles, independent of environmental conditions.
Smart Images
Figure 2025185726000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a method for manufacturing dental objects and a printer for manufacturing dental objects. [Background technology]
[0002] Drying or evaporating inorganic-filled carrier liquids based on polar or non-polar solvents such as water, ethanol, ethylene glycol, or mixtures thereof is difficult and time-consuming in 3D printing, so each printed layer must dry as quickly as possible.
[0003] It is generally difficult to determine when a printed layer has completely dried. Empirical values are generally used to determine the appropriate drying time for each printed layer. However, reliable monitoring of the degree of drying is not available. In principle, the carrier liquid should dry to a degree that prevents mechanical solidification and cracking. Summary of the Invention [Problem to be solved by the invention]
[0004] The technical problem of the present invention is to improve the three-dimensional printing process. [Means for solving the problem]
[0005] This technical problem is solved by the subject matter of the independent claims. Technically advantageous embodiments are the subject matter of the dependent claims, the description and the drawings.
[0006] According to a first aspect, the technical problem is solved by a method for manufacturing a dental object, the method including the steps of printing a printing layer of the dental object, evaporating a solvent from the printed printing layer, and detecting a temperature profile during evaporation of the solvent. This method achieves the technical advantage of being able to monitor and control the drying of the solvent-based carrier liquid in the printing layer.
[0007] In a technically advantageous embodiment of the method, the method is controlled based on the detected temperature profile, thereby achieving the technical advantage of being able to actively adjust or control the printer based on, for example, the exothermic or endothermic reaction of the printing layer.
[0008] In another technically advantageous embodiment of the method, the next printing layer is printed when the temperature of the temperature profile reaches a predetermined value, thereby achieving the technical advantage that the method can be continued immediately, for example, when a predetermined temperature or temperature profile is reached.
[0009] In a further technically advantageous embodiment of the method, an air flow is directed onto the printed layer to evaporate the solvent, which can, for example, accelerate the evaporation of the solvent and achieve the technical advantage of an increased temperature drop.
[0010] In a further technically advantageous embodiment of the method, the air flow to the printing layer is controlled based on the detected temperature profile, thereby achieving the technical advantage that, for example, the air flow can be adjusted depending on the temperature profile.
[0011] In a further technically advantageous embodiment of the method, the temperature, humidity or amount of air supplied of the air flow is controlled based on the detected temperature profile, thereby achieving the technical advantage that particularly suitable parameters of the air flow can be changed, for example.
[0012] In another technically advantageous embodiment of the method, the printing layer is maintained between a maximum temperature and a minimum temperature, which achieves the technical advantage of, for example, preventing melting of the support material.
[0013] In a further technically advantageous embodiment of the method, the temperature profile is detected by an infrared camera or an electromagnetic radiation sensor, which achieves the technical advantage that, for example, the temperature profile can be detected efficiently and the drying can be adjusted depending on the construction height.
[0014] In a further technically advantageous embodiment of the method, the temperature profile is detected by a self-learning algorithm, which achieves the technical advantage that, for example, an algorithm can be used instead of an infrared sensor, thus reducing the associated effort.
[0015] In a further technically advantageous embodiment of the method, the detected temperature profile is compared with a predetermined temperature profile, thereby achieving the technical advantage that, for example, a deviation between the predetermined temperature profile and the detected temperature profile can be determined.
[0016] In a further technically advantageous embodiment of the method, the thickness or water content of the printing layer or the amount of carrier liquid is determined based on the comparison, thereby achieving the technical advantage that, for example, information about the printing properties can be obtained from the temperature profile.
[0017] In another technically advantageous embodiment of the method, print head functionality is determined based on the comparison, thereby achieving the technical advantage of being able to identify malfunctions of the print head or individual print nozzles, for example. Print head droplet size can also be determined.
[0018] According to a second aspect, the technical problem is solved by a printer for producing dental objects, comprising an evaporation element for evaporating a solvent from a printed printing layer and a detection element for detecting a temperature profile during evaporation of the solvent, which achieves the same technical advantages as the method according to the first aspect.
[0019] In a technically advantageous embodiment of the printer, the printer comprises an infrared camera or an electromagnetic radiation sensor for detecting the temperature profile.
[0020] In another technically advantageous embodiment of the printer, the printer includes a fan for generating an air flow toward the printing layer. This can, for example, accelerate the evaporation of the solvent, achieving the technical advantage of increasing the temperature drop in the temperature profile. This temperature drop generated by the fan at the surface of the printing layer can be used to draw conclusions about the solvent content of the printing layer. A new increase in the temperature of the printing layer indicates a decrease in the solvent content in the printing layer.
[0021] An embodiment of the invention is shown in the drawings and is explained in more detail below. [Brief explanation of the drawings]
[0022] [Figure 1] 1 is a schematic diagram of the structure of a three-dimensional printer with cooling according to the present invention; [Figure 2] 2 is a schematic diagram of the surface temperature during drying of the printing layer according to the present invention. FIG. [Figure 3] 1 is a block diagram of a method for manufacturing a dental object according to the present invention. DETAILED DESCRIPTION OF THE INVENTION
[0023] 1 shows a schematic diagram of the structure of a three-dimensional printer 200. The printer 200 applies a carrier liquid 113 to a movable build platform 119 in successive print layers 103-1, . . . , 103-n to produce a dental object 100.
[0024] The printed layers 103-1, ..., 103-n may be composed of a carrier liquid 113 with a single-phase or multi-phase inorganic material such as doped partially or fully stabilized zirconium oxide (stabilizer: Y3+, La3+, Mg2+, Ca2+, Ce3+, or Ce4+, or a combination thereof), or aluminum oxide or MgO-doped aluminum oxide, or a combination thereof (inorganic composite).
[0025] The carrier liquid 113 may contain organic additives, such as diols, triols, polyvinyl alcohols, polyethylene glycols, polyacrylates, polyvinylpyrrolidones and cellulose derivatives, which have a positive effect on drying and increase the strength of the dental object 100 in the green state.
[0026] The drying time of each of the printed layers 103-1, ..., 103-n varies due to different amounts of carrier liquid 113, build heights, build platform temperatures, or solids contents used for each of the printed layers 103-1, ..., 103-n. Because each printed layer 103-1, ..., 103-n is formed by a different two-dimensional pattern (slice image), a different amount of carrier liquid 113 is applied to each printed layer 103-1, ..., 103-n.
[0027] Generally, it is difficult to determine the drying state of the carrier liquid 113 at different points. Various external influences, such as temperature or humidity, also affect the drying behavior of the carrier liquid 113.
[0028] An infrared camera or electromagnetic radiation sensor is used as the detection element 115 to determine the temperature profile 107 of the new wet print layers 103-1, ..., 103-n over time while a fan 117 is used as the evaporation element to blow an airflow onto the print layers 103-1, ..., 103-n. The airflow can be either cool air or warm air. The detection element 115 generates a time series of digital data reflecting the temperature of the print layers.
[0029] The airflow generated on the surface of the new printing layers 103-1, ..., 103-n promotes evaporation of the water used as a solvent. The promoted evaporation cools the printing layers 103-1, ..., 103-n. This effect is called evaporative cooling, evaporation enthalpy, or evaporative chill. The energy required for evaporation is extracted from the printing layers 103-1, ..., 103-n. Thus, the evaporation process cools the printing layers 103-1, ..., 103-n.
[0030] The resulting airflow removes vapor-saturated air and supplies unsaturated air, creating a larger difference in chemical potential or concentration gradient that favors further evaporation. If the air encounters a solvent-containing wet print layer 103-1, ..., 103-n during its travel before reaching its maximum capacity for absorbing solvent, it absorbs the solvent as evaporated gas.
[0031] Therefore, the air flow increases the temperature difference across the surfaces of the printing layers 103-1, ..., 103-n, resulting in a detected temperature profile with a lower temperature minimum. This leads to improved measurement sensitivity. The temperature profile can then be used to determine whether printing of the next printing layer 103-n+1 can begin.
[0032] This saves time and allows for higher quality drying of the printed layers 103-1, ..., 103-n. On the other hand, drying too quickly can cause cracks in the printed layers 103-1, ..., 103-n. This is a problem in ceramic green bodies (bodies in an unsintered state) because their green density is in the range of 40-60% of the theoretical final density. If cracks occur in the unsintered green body, it will not have sufficient final strength after the sintering process.
[0033] The control unit 121 (controller) is used to control and perform calculations for the printer 200. Because different carrier liquids 113 react differently to airflow, humidity, and heat, the control unit 121 can perform different controls depending on the carrier liquid 113. To this end, the control unit 121 includes, for example, a central processing unit (CPU) and a digital memory for storing programs and data, such as for storing temperature profile data.
[0034] 2 shows a schematic diagram of a temperature profile 107 during drying of the printing layers 103-1, ..., 103-n with water evaporation by airflow and a temperature profile 109 without airflow. Based on the temperature profile 107, it is possible to determine the current drying stage of the applied printing layers 103-1, ..., 103-n using evaporative cooling. Initially, the surface temperature drops to a minimum value, but after a certain time, it rises again.
[0035] From time t0, strong cooling occurs due to the evaporation of water. The evaporation of water draws thermal energy from the printing layers 103-1, ..., 103-n, resulting in a decrease in the temperature of the printing layers 103-1, ..., 103-n. The decrease in temperature depends on how strongly the airflow, e.g., a fan, acts on the printing layers 103-1, ..., 103-n. At time t1, at the minimum value of the profile, the evaporation of water ends and the temperature of the printing layers 103-1, ..., 103-n rises again. At time t2, as soon as the predetermined temperature is reached, the next printing layer 103-n+1 is applied.
[0036] The cooling of the printed layers 103-1, ..., 103-n is detected and recorded by the detection elements 115. This produces a characteristic temperature profile curve 107 that indicates the progression of the surface temperature of the printed layers 103-1, ..., 103-n over time.
[0037] By recording the solvent evaporation and temperature profile 107, the exact drying state of the printing layers 103-1, ..., 103-n can be determined. Based on the temperature profile 107, the printing process can be controlled in different ways and at different times.
[0038] For example, the optimal time for printing the next printing layer 103-n+1 can be actively determined for each printing layer 103-1, ..., 103-n based on the temperature profile 107. The temperature profile data is stored as digital data in the memory of the control unit 121, for example.
[0039] 3 is a diagram showing the measurement of the surface temperature during drying of the printed layers 103-1, ..., 103-n. The solids content is 70 wt %, the water is about 27 wt %, and the binder is about 3 wt %. The density of the printed layers 103-1, ..., 103-n is 2.4 g / cm for yttrium-stabilized ZrO2, not considering the organic components. 3 ~3.6 g / cm 3 If the organic component is taken into account, the density will be lower.
[0040] In the diagram shown, an air flow is generated with an air volume of 5 L / min and a temperature of 50°C. The relative humidity is less than 60%. With a zirconium slurry as the carrier liquid 113 having a water content of 30% by weight and a thickness of the printing layers 103-1, ..., 103-n of 6 μm, a temperature drop of 10°C was observed after printing. After a certain time, the temperature difference between the surface of the printing layers 103-1, ..., 103-n and the printed printing layers 103-1, ..., 103-n drops to 0°C.
[0041] The temperature profile 107 can be used to detect whether the print head is not discharging any carrier liquid 113 or if it is discharging too little. For example, if a characteristic temperature profile 107 with a minimum value is not detected in the print area, the print head is not discharging carrier liquid 113 there. In this way, nozzle failures in the print head can be identified. Failures of single pixels or nozzles can be identified. It is also possible to detect whether a uniform layer application exists. The print head is not sprayed to prevent nozzle clogging or drying. An ideal process window favors coalescence, i.e., bonding of the individual layers and drying without cracks.
[0042] This method is independent of the air conditioning of the installation space, so printing can be performed in different environments, such as at different temperatures and humidity levels, without compromising print quality. This eliminates the need for air conditioning in the room.
[0043] During the printing process of the printing layers 103-1, ..., 103-n, it is also possible to keep the used support material 123, e.g., wax, within a predetermined temperature range between a maximum and a minimum temperature. Excessive cooling of the support material 123 can, for example, result in shrinkage, which reduces the printing accuracy of the dental object 100. On the other hand, if the support material 123 becomes too hot, it melts. In these cases, the dental object 100 will not be printed with the desired accuracy either. In that case, the entire layer structure will be at the same temperature as the build platform.
[0044] Furthermore, the location of the minimum value or drying time in the temperature profile 107 can be used to detect the thickness of the applied carrier liquid 113, i.e., the thickness of the printed layers 103-1, ..., 103-n. Furthermore, the solids content of the carrier liquid 113 can be measured or determined to change during printing. This can be detected by the fact that the carrier liquid 113 dries in a shorter or longer time than specified by the reference value in the temperature profile 107.
[0045] Additionally, standardized test prints can be performed with predetermined parameters. If the measured parameters of the temperature profile 107 deviate from the specified parameters, the carrier liquid 113 has a different composition than required. In this way, an improper carrier liquid 113 can be detected, and a warning can be issued to the user that the carrier liquid 113 does not meet the specified criteria.
[0046] To ensure uniform, crack-free drying of the printing layers 103-1, ..., 103-n, the carrier liquid 113 must not dry too quickly from its liquid state. To this end, the amount of air supplied, the temperature of the airflow, or the humidity can be adjusted during each drying stage. Depending on the drying conditions, for example, the amount of air can be reduced and then increased again.
[0047] The temperature of the supplied hot air can also be reduced until the carrier liquid 113 has a certain strength and can no longer form cracks, and then the temperature can be increased again, causing the carrier liquid 113 to quickly reach the correct temperature for the next printed layer 103-n+1.
[0048] 3 shows a block diagram of a method for manufacturing a dental object 100. The method includes step S101 of printing printing layers 103-1, ..., 103-n of the dental object 100. In step S102, the solvent 105 of the printed printing layers 103-1, ..., 103-n is evaporated. In step S103, a temperature profile 107 during evaporation of the solvent 105 is detected.
[0049] This method allows the degree of drying and the evaporation process to be monitored with high precision. The layer-by-layer construction process of the ceramic printing layers 103-1, ..., 103-n can be carried out in a controlled manner to avoid uneven drying or crack propagation.
[0050] This method can be used to dry the printing layers 103-1, ..., 103-n quickly and without cracks. Measuring the drying state via the temperature profile 107 allows for further control to accelerate or slow down the drying process. This allows for printing at higher speeds, with better quality and fewer rejects. This method is independent of humidity and air pressure. Therefore, air conditioning is not required, making the method more resource-efficient.
[0051] All of the features described and shown in connection with the individual embodiments of the invention can be provided in different combinations in the subject matter according to the invention in order to simultaneously realize their advantageous effects.
[0052] All method steps may be performed by apparatus suitable for performing the respective method step. All functions performed by the subject features may be a method step of the method.
[0053] The scope of protection of the invention is given by the claims and is not limited by the features described in the specification or shown in the drawings. [Explanation of symbols]
[0054] 100 Dental Objects 103 Printing layer 105 Solvent 107 Temperature Profile 109 Temperature profile without drying 111 Evaporation element 113 Carrier fluid 115 Detection Elements 117 fans 119 Building Platform 121 Control Unit 123 Supporting materials 200 printers
Claims
1. 1. A method for manufacturing a dental object, comprising: - printing a printing layer of a dental object; - evaporating the solvent of the printed printing layer; detecting the temperature profile during evaporation of the solvent.
2. 2. The method of claim 1, wherein the control is based on a detected temperature profile.
3. 3. The method according to claim 1, wherein the next printing layer is printed when the temperature of the temperature profile reaches a predetermined value.
4. 10. The method of claim 1, wherein a stream of air is directed onto the printed layer to evaporate the solvent.
5. 5. The method of claim 4, wherein the airflow is controlled based on the detected temperature profile.
6. 6. The method of claim 5, wherein the temperature, humidity, or amount of airflow provided is controlled based on the detected temperature profile.
7. The method of claim 1 , wherein the printed layer is maintained between a maximum temperature and a minimum temperature.
8. The method of claim 1 , wherein the temperature profile is detected by an infrared camera or an electromagnetic radiation sensor.
9. The method of claim 1 , wherein the temperature profile is detected by a self-learning algorithm.
10. 10. The method of claim 1, further comprising comparing the detected temperature profile to a predetermined temperature profile.
11. The method of claim 10, wherein the thickness of the printed layer, the moisture content, or the amount of carrier liquid is determined based on the comparison.
12. The method of claim 10, wherein the functionality of the printhead is determined based on the comparison.
13. 1. A printer for producing dental objects, comprising: an evaporation element for evaporating the solvent of the printed printing layer; a detection element for detecting the temperature profile during evaporation of the solvent.
14. 14. The printer of claim 13, further comprising an infrared camera or electromagnetic radiation sensor for detecting the temperature profile.
15. 15. The printer according to claim 13, further comprising a fan for generating an air flow in the printing layer.