Method for printing ceramic structure through SLS equipment and high-temperature 3D printing device thereof

Abstract

The invention provides a method for printing a ceramic structure through SLS equipment and a high-temperature 3D printing device thereof.The high-temperature 3D printing device comprises a printing forming part used for conducting ceramic powder laying, printing and forming, the printing forming part is provided with a heating body assembly, and the heating body assembly is used for forming the environment temperature of 500 DEG C or above in a forming cavity; the active cooling part abuts against the rear end of the printing forming part and is used for cooling the laser, the galvanometer and the sensor component; the circulating filtering part abuts against the printing forming part and the active cooling area and is used for filtering reaction products in the ceramic printing process; and the observation window is arranged at the front end of the printing and forming part and is used for observing the work of the printing and forming part. According to the ceramic 3D printing equipment, the heating body assembly is arranged and used for forming the environment temperature of 500 DEG C or above in the forming cavity, and printing work of the ceramic 3D printing equipment is achieved; and by arranging the circulating filtering part, the problem that a galvanometer is polluted by volatilization of reactants of the ceramic 3D printing high-temperature machine is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of additive manufacturing, and particularly relates to a method for printing a ceramic structure by using an SLS device and a high-temperature 3D printing device. BACKGROUND

[0002] The existing 3D printing devices are mainly divided into four categories, namely, extrusion forming (FDM, DIW), photosensitive polymerization forming (SL, DLP), powder bonding forming (IJP, 3DP), and powder sintering forming (SLS, SLM). Among them, the SLM device is mainly used for printing iron-based, nickel-based alloys, such as stainless steel, high-temperature alloy, and aluminum alloy, titanium alloy, and other metal materials; and the SLS device is mainly used for printing nylon, PEEK, and other non-metallic materials.

[0003] For example, Chinese patent application No. CN201910628178.3 discloses a preparation method for a ceramic-based complex structural part based on selective laser sintering, which comprises the following steps: 1) preparing a blank; 2) assembling the mold; 3) dry pressing treatment; and 4) sintering. The preparation method uses indirect selective laser sintering technology to form a ceramic-based blank, and then fills the low-compressibility powder into the internal pores and outer surface of the ceramic-based blank, thereby limiting the collapse and damage of the ceramic-based blank under external force. Since the compressibility of the filled low-compressibility powder is lower than that of the ceramic-based blank, under the action of mechanical load, the external force is uniformly transmitted to the ceramic-based blank from all directions through the filled low-compressibility powder, so that the particles in the blank body are close to each other, the porosity is reduced, and the density is improved. In the high-temperature solid-phase or liquid-phase sintering process, the particles in the blank body are bonded to form a skeleton, the grains grow, and the pores further decrease, thereby forming a dense ceramic-based complex structural composite material part.

[0004] For another example, Chinese patent application No. CN201710238622.1 discloses a preparation method for a C / C-SiC composite material part and a product thereof, which comprises the following steps: (a) preparing a carbon fiber / phenolic resin composite powder by using a solvent evaporation method; (b) forming an initial blank of the part by using a 3D printing process according to a three-dimensional model of the part; (c) performing a first densification treatment on the initial blank to obtain a C / C porous body; and (d) performing a molten silicon infiltration reaction, a high-temperature silicon removal process, and a second densification treatment on the C / C porous body to obtain a final C / C-SiC part. The application can near-net-shape a C / C-SiC composite material part with a complex structure, and the method has a short production cycle, low cost, and a low residual silicon content of the obtained C / C-SiC composite material part, and has excellent performance.

[0005] For another example, Chinese invention patent application No. CN201910447966.2 discloses a laser selective sintering forming equipment, system and method for forming a large and complex part. The system is composed of a guide rail integrated laser selective sintering forming equipment, a powder cleaning equipment, and a post-curing-carburizing equipment. After the forming mechanism completes laser selective sintering forming of a slice layer on the forming table, the vertical driving mechanism is raised by one slice layer height. In the case that the height of the forming table remains unchanged, the height of the forming mechanism is raised layer by layer to realize layer-by-layer processing of the part to be formed. The horizontal driving mechanism is used to drive the forming mechanism or equipment above it to separate from the forming table. The entire set of equipment uses a fixed forming table to complete the entire manufacturing process without moving the part to be formed, solving the problem of small size and low yield of complex parts in the prior art, realizing the immobility of the formed part in SLS forming, avoiding the collapse, bending and deformation of the part due to movement, and further being applicable to the manufacturing of large parts.

[0006] In recent years, high-performance structural ceramic materials have shown broad application prospects, but due to the limitations of traditional processes, they cannot be used to prepare complex-shaped ceramic parts. In order to broaden the application market of ceramic materials, 3D printing technology needs to be adopted. However, the existing technical equipment cannot realize 3D printing of high-performance ceramic structures, such as silicon carbide-based ceramics, which have large internal stress, are prone to cracking, and have high shrinkage during the printing process. The key to solving this problem is to maintain a consistent temperature in the longitudinal (Z-direction) during 3D printing, which requires the forming cabin of the printing equipment to be preheated to an extremely high temperature to solve the cracking problem of 3D printed ceramic parts and improve their mechanical properties.

[0007] However, existing SLM metal printing equipment can only preheat the substrate, with a maximum preheating temperature of 200°C, and cannot preheat the entire forming chamber. SLS high-molecular printing equipment can preheat the substrate and the forming chamber, but the maximum preheating temperature is only 350°C, which cannot reach the required temperature for printing high-performance structural ceramic materials, and cannot solve the problems of cracking and high shrinkage during the printing process.

[0008] In addition, ceramic structure 3D printing also has the problem of contamination of the galvanometer by reactants at high temperatures, and the problem of poor flowability and difficult powder laying of high-performance ultra-fine powders (D50≤20µm).

[0009] Based on the above technical problems existing in the prior art, the present application provides a method for printing ceramic structures using SLS equipment and a high-temperature 3D printing device thereof. SUMMARY

[0010] The application provides a method for printing ceramic structures by using an SLS device and a high-temperature 3D printing device, wherein in the printing process, on one hand, the forming chamber is preheated to 500 DEG C, so that the consistency of the temperature in the vertical direction (Z direction) during the 3D printing process is ensured, and the temperature requirement of the ceramic material 3D printing device is met; meanwhile, the problem of ceramic cracking and large shrinkage during the printing process is further solved by controlling double lasers, i.e. preheating by the main laser and shaping by the following laser; on the other hand, the problem of the reaction volatile pollution of the galvanometer of the ceramic 3D printing high-temperature machine is solved by adopting a circulating filtering mode; finally, the problems of powder laying difficulty caused by poor flowability of superfine ceramic powder are solved by the cooperative control of the scraper and the roller, i.e. the scraper is laid flat, and the roller is compacted.

[0011] The application adopts the following technical scheme:

[0012] The method for printing ceramic structures by using the SLS device comprises the following steps.

[0013] In step 1, the ceramic composite powder is prepared by using a solvent evaporation method, the ceramic powder, the sintering aid and the thermoplastic phenolic resin are mixed in proportion, are uniformly dispersed in an organic solvent, and after distillation, drying, grinding and screening, the thermoplastic phenolic resin uniform film ceramic composite powder with a particle size distribution of 10-150 microns is obtained, wherein the volume ratio of the ceramic powder to the thermoplastic phenolic resin is (2-8):(2-8), and the mass fraction of the sintering aid is 3-15%.

[0014] In step 2, the SLS ceramic high-temperature 3D printing device is started, the printing forming part, the circulating filtering part, the air compressor and the heating body assembly and the multi-laser galvanometer unit are sequentially powered on, the control program of the SLS device starts self-checking, and it is ensured that the production environment, the water, electricity and gas system and the pipeline and auxiliary machine system normally operate.

[0015] In step 3, the laser focusing program is executed in the control system of the SLS device, and it is ensured that the laser focal point falls on the horizontal position of the forming base plate.

[0016] In step 4, the ceramic composite powder prepared in step 1 is added to the powder feeding cylinder piston, and the addition amount reaches the predetermined standard.

[0017] In step 5, the roller test is executed in the control system of the SLS device, and the forming cylinder piston is pushed and the base layer powder is prepared.

[0018] In step 6, the heating body assembly is started in the control system of the SLS device, the forming chamber is heated, and the forming base plate is preheated.

[0019] In step 7, the wind field preheating program is executed in the control system of the SLS device, and the air intake and exhaust and the wind field preheating are started.

[0020] Step 8, when the temperature of the forming chamber reaches the predetermined sealing inspection threshold temperature, the component sealing inspection of the SLS equipment is carried out;

[0021] Step 9, after the sealing inspection, the forming chamber heating is continued by the heating body assembly;

[0022] Step 10, the forming chamber heating is completed by the heating control system in the forming chamber, and the temperature is maintained at 500 DEG C by the comprehensive wind field control;

[0023] Step 11, the laser device is started by the control system of the SLS equipment, and the printing work is started in cooperation with the roller, the printing reaction product is blown by the wind field to the air inlet pipe, and then enters the filter after the air inlet pipe, the reaction product is filtered out, the clean air after filtering is discharged by the air outlet after the circulating fan, and enters the printing forming part, and the circulating filtering is realized;

[0024] Step 12, after the printing manufacturing work is completed according to the control system program of the SLS equipment, the laser device and the roller are closed, and the core mechanical parts participating in the movement in the printing process are restored to the initial standby position;

[0025] Step 13, the wind field preheating, the substrate preheating and the forming chamber heating are closed, and the temperature is gradually reduced to normal temperature by the wind field;

[0026] Step 14, the wind field is closed, the active cooling part is closed, the forming chamber door is opened, and the part is taken out, if subsequent processing is not required, the SLS equipment is shut down, and cleaning and maintenance work is performed.

[0027] Further, in step 6, the active cooling part starts to cool the laser, the galvanometer and the sensor part at the same time when the heating body assembly preheating starts.

[0028] Further, in step 7, the direction of the wind provided by the wind field is from the air outlet to the air inlet.

[0029] The application also provides a ceramic structure high-temperature 3D printing device of an SLS equipment, comprising:

[0030] The printing forming part is used for ceramic powder laying, printing and forming, wherein the printing forming part is provided with a heating body assembly, and the heating body assembly is used for forming an environmental temperature above 500 DEG C in the forming cavity;

[0031] The active cooling part is abutted to the rear end of the printing forming part, and is used for cooling the laser, the galvanometer and the sensor part;

[0032] The circulating filtering part is abutted to the printing forming part and the active cooling area, and is used for filtering the reaction product in the ceramic printing process;

[0033] An observation window is arranged at the front end of the printing forming part for observing the operation of the printing forming part.

[0034] Further, the printing forming part comprises a laser box, a frame, a roller, a forming cylinder piston, a powder feeding cylinder piston, a galvanometer, a temperature sensor, an air outlet and a water cooling plate, the water cooling plate is fixedly installed above the frame, the laser box is fixedly installed above the water cooling plate, the galvanometer is fixedly arranged at the laser outlet side of the laser box to change the laser direction and control the laser path, the temperature sensor is located above the inside of the frame to monitor the temperature, the air outlet is opened at the rear side of the frame to blow out the circulating air, the forming cylinder piston and the powder feeding cylinder piston are arranged below the frame, and the roller is rollably arranged inside the frame and rolls from the powder feeding cylinder piston side to the forming cylinder piston side to realize powder laying, the powder feeding cylinder piston moves up to feed powder before powder laying, the roller moves from the forming cylinder piston side back to the powder feeding cylinder piston side to return to the home position after powder laying, and then the laser starts to work, the laser path is controlled by the galvanometer, a layer of powder is sintered, the forming cylinder piston moves down after completion to empty the space for the next layer of powder laying, and the cycle continues until the printing is completed.

[0035] Further, the heating body assembly comprises an assembly shell, a thermocouple and a heating rod fixedly arranged on the assembly shell, and aerogel thermal insulation filled in the assembly shell, and the heating directions of the thermocouple and the heating rod are opposite to the printed workpiece.

[0036] Further, the assembly shell comprises an upper cover plate, a lower cover plate, an inner cover plate, an outer cover plate and a side cover plate, the inner cover plate and the outer cover plate are arranged in parallel, the upper cover plate is covered above the inner cover plate and the outer cover plate, the lower cover plate is covered below the inner cover plate and the outer cover plate, and the side cover plate is covered at the side end of the inner cover plate and the outer cover plate.

[0037] Further, the circulation filtering part comprises an air inlet duct, a pipeline, a filter, a circulating fan and an air outlet duct, the air inlet duct is communicated with one end of the pipeline, the other end of the pipeline is communicated with the inlet of the filter, the outlet of the filter is communicated with the circulating fan, and the circulating fan is communicated with the air outlet duct; after the circulating fan is started, a pressure difference is formed between the air outlet duct and the air inlet duct, an air field is generated in the printing forming part, the direction of the air field is from the air outlet duct to the air inlet duct, the printing reaction product can be blown to the air inlet duct, enters the filter after passing through the pipeline, and the reaction product is filtered out, the clean air after filtering is discharged from the air outlet duct again after passing through the circulating fan and enters the printing forming part.

[0038] Further, the air outlet is connected with the air outlet, the air outlet is arranged on the upper part of the rear side of the forming cavity of the printing forming part, is located on the rear side of the frame, the outlet direction of the air outlet is towards the inside of the forming cavity of the printing forming part, and the air outlet is used for blowing clean air into the forming cavity; the air outlet is arranged below the rear of the galvanometer, the galvanometer is arranged above the forming cavity of the printing forming part, the galvanometer is fixed through the laser box and the water-cooled plate, the outlet of the air outlet is arranged on the rear side of the galvanometer and is lower than the horizontal plane of the galvanometer, which helps to avoid that the air field directly blows to the galvanometer, and prevents that vibration or temperature fluctuation affects the accurate control of the laser path.

[0039] The air inlet is arranged on the lower part of the front side of the forming cavity of the printing forming part, is located on the front end of the bottom of the frame, is close to the lower part of the observation window; the inlet direction of the air inlet is towards the inside of the forming cavity of the printing forming part, and the air inlet is used for inhaling air containing reaction products; the air inlet is located below the front of the galvanometer and forms a diagonal line with the air outlet.

[0040] The air field direction flows from the air outlet to the air inlet, that is, from the upper part of the rear side of the forming cavity of the printing forming part to the lower part of the front side, and the galvanometer is arranged above the forming cavity of the printing forming part.

[0041] Further, the active cooling part comprises a water-cooled plate shell and a water inlet, a water outlet, a first water-cooled pipeline, a second water-cooled pipeline and a temperature sensor channel fixedly arranged on the water-cooled plate shell, the first water-cooled pipeline is communicated with the second water-cooled pipeline, the water inlet and the water outlet are respectively communicated with two ends of the first water-cooled pipeline, and the temperature sensor channel is communicated with the second water-cooled pipeline.

[0042] Further, the filter adopts a high-temperature-resistant ceramic filter screen.

[0043] Compared with the prior art, the superior effects of the present application are that:

[0044] 1. The SLS equipment ceramic structure high-temperature 3D printing device disclosed by the present application is provided with a heating body assembly, which is used for forming an ambient temperature of 500 DEG C or above in the forming cavity, realizes the printing operation of the ceramic 3D printing device, greatly reduces the temperature difference between the laser scanning area and the surrounding powder, the sintering process is more gentle, and the thermal stress is effectively released; the closed-loop filtering system composed of the directional air field from the rear upper part to the front lower part and the high-temperature-resistant ceramic filter realizes the source capture and real-time removal of the reaction products.

[0045] 2. The SLS equipment ceramic structure high-temperature 3D printing device disclosed by the present application is provided with a circulating filtering part, solves the problem that the reaction products of the ceramic 3D printing high-temperature machine volatilize and pollute the galvanometer, the design of the directional air field makes the airflow flow away from the galvanometer, effectively pushes the smoke dust away from the optical area, and the active cooling part ensures that the galvanometer and the laser always work at a safe temperature.

[0046] 3. The SLS equipment ceramic structure high-temperature 3D printing device, the heating body assembly cooperates with the circulating air field, the heating rod and the thermocouple provide accurate heat input and feedback, and the circulating air field acts as a thermal agitator, so that the heat distribution in the cavity is more uniform.

[0047] 4. The SLS equipment ceramic structure high-temperature 3D printing device, the function depth of the air compressor is integrated, is not only used for driving the piston and the roller, is also used for pulse back blowing of the filter, and can maintain the micro-positive pressure of the cavity to prevent external air from entering; by reasonably setting the air field and setting the observation window in front of the printing forming part, and utilizing the directional air field to keep it clean, the operator can observe the powder laying, laser sintering and other key processes in real time, so that problems can be found in time and process adjustment is facilitated. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 is a structural schematic view of the SLS equipment ceramic structure high-temperature 3D printing device in the embodiment of the application;

[0049] Figure 2-1 is a structural schematic view of the printing forming part in the embodiment of the application;

[0050] Figure 2-2 is a structural schematic view of the inside of the frame in the embodiment of the application;

[0051] Figure 3-1 is a structural schematic view of the first angle of the heating body assembly in the embodiment of the application;

[0052] Figure 3-2 is a structural schematic view of the second angle of the heating body assembly in the embodiment of the application;

[0053] Figure 4 is a structural schematic view of the circulating filtering part in the embodiment of the application;

[0054] Figure 5 is a structural schematic view of the active cooling part in the embodiment of the application;

[0055] Figure 6 is a printing process schematic view of the SLS equipment ceramic structure high-temperature 3D printing device in the embodiment of the application;

[0056] REFERENCE NUMERALS:

[0057] 1, printing forming part; 11, laser box; 12, frame; 13, heating body assembly; 131, upper cover plate; 132, lower cover plate; 133, inner cover plate; 134, outer cover plate; 135, side cover plate; 136, thermocouple; 137, heating rod; 14, roller; 15, forming cylinder piston; 16, powder feeding cylinder piston; 17, galvanometer; 18, temperature sensor; 19, air outlet;

[0058] 2, circulation filter part; 21, air inlet; 22, pipeline; 23, filter; 24, circulation fan; 25, air outlet;

[0059] 3, active cooling part; 31, water cooling plate; 311, water inlet; 312, water outlet; 313, water cooling plate shell; 314, main water cooling pipeline; 315, auxiliary water cooling pipeline; 316, temperature sensor channel;

[0060] 4, observation window. DETAILED DESCRIPTION

[0061] In order to enable the above-mentioned purposes, features and advantages of the present application to be more clearly understood, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments, and it should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0062] EMBODIMENT

[0063] As shown in the method for printing a ceramic structure by the SLS device, comprising: Figure 6

[0064] Step 1, a ceramic composite powder is prepared by a solvent evaporation method, ceramic powder, sintering aid and thermoplastic phenolic resin are mixed in proportion, added into an organic solvent for ultrasonic dispersion, and after distillation, drying, grinding and screening, a thermoplastic phenolic resin uniform film ceramic composite powder with a particle size distribution of 10-150 μm is obtained, wherein the volume ratio of ceramic powder to thermoplastic phenolic resin is (2-8):(2-8), and the mass fraction of sintering aid is 3-15%;

[0065] Step 2, start the SLS ceramic high-temperature 3D printing device, and sequentially power on the forming part 1, the circulation filter part 2, the air compressor and the heating body assembly 13 and the multi-laser galvanometer unit. The control program of the SLS device starts self-checking to ensure that the production environment, the water, electricity and gas system and the pipeline and auxiliary machine system are normally operated;

[0066] Step 3, execute the laser focusing program in the control system of the SLS device to ensure that the laser focal point falls on the horizontal position of the forming substrate;

[0067] Step 4, powder adding, the ceramic composite powder prepared in step 1 is added to the powder feeding cylinder piston 16, and the addition amount reaches the predetermined standard;

[0068] Step 5, roller 14 test, execute the roller 14 test program in the control system of the SLS device, and push and prepare the base layer powder for the forming cylinder piston 15;

[0069] ​Step 6, control the heating assembly 13 to start in the control system of the SLS device, heat the forming chamber, and start preheating the forming substrate;

[0070] Step 7, execute the wind field preheating program in the control system of the SLS device to start the air intake and exhaust and preheat the wind field;

[0071] Step 8, when the temperature of the forming chamber reaches the predetermined sealing inspection threshold temperature, perform the component sealing inspection of the SLS device;

[0072] Step 9, after the sealing inspection passes, continue to heat the forming chamber through the heating assembly 13;

[0073] Step 10, complete the chamber heating through the heating control system in the forming chamber, and keep the temperature at 500℃ through the comprehensive wind field control;

[0074] Step 11, start the laser device through the control system of the SLS device, start the printing work with the roller 14, and the wind field blows the printing reaction product to the air intake pipeline, then into the filter through the air intake pipeline, filters out the reaction product, and the filtered clean air is discharged from the air outlet after passing through the circulating fan, enters the printing forming part 1, and realizes the circulating filtration;

[0075] Step 12, after completing the printing manufacturing work according to the control system program of the SLS device, close the laser device and the roller 14, and restore the core mechanical components involved in the printing process to the initial standby position;

[0076] Step 13, close the wind field preheating, substrate preheating, and forming chamber heating, and gradually reduce the temperature to normal temperature through the wind field;

[0077] Step 14, close the wind field, close the active cooling part, open the forming chamber door, take out the part, if no subsequent processing is needed, shut down the SLS device, and perform the cleaning and maintenance work.

[0078] Further, in step 6, the active cooling part 3 starts to cool the laser, galvanometer, and sensor components at the same time when the heating assembly preheating starts.

[0079] Further, in step 7, the direction of the air provided by the wind field is from the air outlet to the air intake.

[0080] Specifically, the air compressor is connected with the forming cylinder piston 15 and the powder feeding cylinder piston 16 through the gas circuit pipeline system, compressed air output by the air compressor drives the lifting cylinders for driving and controlling the forming cylinder piston 15 and the powder feeding cylinder piston 16 after passing through the precise air pressure regulating valve and the direction control valve, so as to provide power for the accurate and stable lifting of the two pistons; during the printing process, the forming cylinder piston 15 needs to be lowered layer by layer, and the powder feeding cylinder piston 16 needs to be raised layer by layer, and these actions are accurately controlled by the SLS equipment pneumatic system, so as to ensure the accuracy of powder laying and forming.

[0081] The air compressor is connected with the driving mechanism of the roller 14 through the gas circuit pipeline system, and compressed air drives the cylinder or the pneumatic motor for driving and controlling the translational motion of the roller 14, so as to provide power for the reciprocating rolling powder laying of the roller 14 between the powder feeding cylinder and the forming cylinder.

[0082] The air compressor is connected with the filter 23 of the circulating filtering part 2 through the gas circuit pipeline system, one compressed air pipeline is connected to the deslagging port or the back-blowing cleaning system of the filter 23, and is used for automatically cleaning the filter 23; when the reaction product (smoke dust) accumulated on the high-temperature-resistant ceramic filter screen is too much, the pulse high-pressure airflow provided by the air compressor can be reversely blown into the filter 23, so as to shake off the filter cake, restore the ventilation efficiency of the filter 23, prolong the service life of the filter 23, and realize continuous printing.

[0083] The air compressor is connected with the sealed cavity of the printing and forming part 1 through the gas circuit pipeline system, and one compressed air pipeline can be introduced into the forming cavity or the interlayer of the shell, so as to maintain the micro-positive pressure inside the cavity and prevent the invasion of external air; in the high-temperature printing environment above 500 DEG C, the entry of external cold air will cause temperature fluctuation and oxidation, and affect the ceramic sintering quality, and the micro-positive pressure can effectively prevent the invasion of untreated air; the micro-positive pressure environment cooperates with the circulating air field, and helps to more effectively push the printing reaction product to the air inlet 21.

[0084] As shown in Figure 1 The application also provides an SLS equipment ceramic structure high-temperature 3D printing device, which comprises:

[0085] The printing and forming part 1 is used for ceramic powder laying, printing and forming, wherein the printing and forming part 1 is provided with a heating body assembly 13, and the heating body assembly 13 is used for forming an environmental temperature above 500 DEG C in the forming cavity;

[0086] The active cooling part 3 is abutted to the rear end of the printing and forming part 1, and is used for cooling the laser, the galvanometer and the sensor components;

[0087] The circulating filtering part 2 is abutted to the printing and forming part 1 and the active cooling part 3, and is used for filtering the reaction product in the ceramic printing process;

[0088] An observation window 4 is arranged at the front end of the printing forming part 1, and is used for observing the operation of the printing forming part.

[0089] Specifically, the SLS equipment ceramic structure high-temperature 3D printing device is a box-shaped structure, the front end of the printing forming part 1 is provided with a handle, the active cooling part 3 abuts against the rear end of the printing forming part 1 to provide cooling cold, and the circulating filtering part 2 is located at one side end of the printing forming part 1, so as to facilitate the circulation filtering of the forming cavity of the printing forming part 1, and meanwhile, the cooling cold provided by the active cooling part 3 is also facilitated to enter the circulating filtering part.

[0090] The heating body assembly 13 can also have a U-shaped appearance, and is horizontally installed in the cavity, with the opening of the U-shaped appearance facing the inside of the cavity, i.e., the side of the roller 14 guide rail. The assembly shell can be made of stainless steel plate material, and is filled with aerogel thermal insulation body. The stainless steel plate shell surrounds the aerogel thermal insulation body. The height of the heating body assembly 13 is not less than 200 mm.

[0091] Further, as shown in Figure 2-1 and Figure 2-2 , the printing forming part 1 includes a laser box 11, a frame 12, a roller 14, a forming cylinder piston 15, a powder feeding cylinder piston 16, a galvanometer 17, a temperature sensor 18, an air outlet 19, and a water-cooled plate 31. The water-cooled plate 31 is fixedly installed above the frame 12, the laser box 11 is fixedly installed above the water-cooled plate 31, the galvanometer 17 is fixedly arranged at the laser outlet side of the laser box 11 to change the laser direction and control the laser path, the temperature sensor 18 is located above the inside of the frame 12 to monitor the temperature, the air outlet 19 is opened at the rear side of the frame 12 to blow out the circulating air, the forming cylinder piston 15 and the powder feeding cylinder piston 16 are arranged below the frame 12, and the roller 14 is rollably arranged inside the frame 12 and rolls from the side of the powder feeding cylinder piston 16 to the side of the forming cylinder piston 15 to realize powder laying. Before powder laying, the powder feeding cylinder piston 16 moves upward to feed powder. After powder laying, the roller 14 moves from the side of the forming cylinder piston 15 back to the side of the powder feeding cylinder piston 16 to return to the original position. Then, the laser starts to work, the laser path is controlled by the galvanometer 17, a layer of powder is sintered, the forming cylinder piston 15 moves downward to leave space for the next layer of powder, and the cycle continues until the printing is completed.

[0092] Specifically, the roller 14 is an electric roller, for example, a stepping motor can be used to generate power, a belt transmission is used to drive the roller 14 to move, and the functions of forward / reverse rotation and speed regulation of the roller 14 can be realized. The rotation of the roller 14 realizes the compaction of the ceramic powder surface by the roller 14.

[0093] The transmission system including the motor and the belt for driving the roller 14 is located outside the forming chamber, and a heat insulation film or other material is arranged between the transmission system and the forming cavity to insulate the heat of the chamber.

[0094] Further, as shown in Figure 3-1 andFigure 3-2 As shown, the heating body assembly comprises an assembly shell, and a thermocouple 136 and a heating rod 137 fixedly arranged on the assembly shell, aerogel thermal insulation filled in the assembly shell, and the auxiliary heating directions of the thermocouple 136 and the heating rod 137 are opposite to the printed workpiece.

[0095] Further, the assembly shell comprises an upper cover plate 131, a lower cover plate 132, an inner cover plate 133, an outer cover plate 134, and a side cover plate 135, the inner cover plate 133 and the outer cover plate 134 are arranged in parallel, the upper cover plate 131 is covered above the inner cover plate 133 and the outer cover plate 134, the lower cover plate 132 is covered below the inner cover plate 133 and the outer cover plate 134, and the side cover plate 135 is covered at the side end of the inner cover plate 133 and the outer cover plate 134, and the assembly shell is generally a "door" structure, wherein the thermocouple 136 and the heating rod 137 are both installed inside the "door" structure for auxiliary heating opposite to the printed workpiece.

[0096] Specifically, the heating rod 137 adopts a resistance wire rod, which is arranged on the inner surface of the assembly shell, each heating rod 137 has a maximum heating power of 2.5kW, and one heating rod 137 is arranged on the inner surface of each of the left and right sides, for example, arranged in the middle, and two heating rods 137 are arranged on the inner surface of the front side, for example, arranged at the three-equal-interval middle position. The upper segment of the heating rod 137 is inserted into the interior of the assembly shell and connected with the rear cable, and the cable is connected to the cavity heating control system.

[0097] The thermocouple type temperature sensor is arranged at the middle position of the front side of the assembly shell, the end of the thermocouple type temperature sensor is inserted into the interior of the assembly shell and connected with the rear cable, and the cable is connected to the cavity heating control system.

[0098] In specific work, the cavity heating control system is used for controlling the heating temperature in the cavity, and the voltage and current of the heating rod 137 are adjusted through electronic control elements according to the production process requirements, so as to realize the control of input heat, and the cavity heating control system further comprises a current sensor and a voltage sensor for testing the voltage and current of the heating rod 137.

[0099] Further, as shown in FIG. 1, Figure 4As shown, the circulating filtration section includes an air inlet duct 21, a pipe 22, a filter 23, a circulating fan 24, and an air outlet duct 25. The air inlet duct 21 is connected to one end of the pipe 22, and the other end of the pipe 22 is connected to the inlet of the filter 23. The outlet of the filter 23 is connected to the circulating fan 24, and the circulating fan 24 is connected to the air outlet duct 25. After the circulating fan 24 is started, a pressure difference is formed between the air outlet duct 25 and the air inlet duct 21, and an air field is generated in the printing forming section 1. The direction of the air field is from the air outlet duct 25 to the air inlet duct 21, which can blow the printing reaction products into the air inlet duct 21. After passing through the pipe 22, the air enters the filter 23, and the reaction products are filtered out. The filtered clean air is discharged again from the air outlet duct 25 after passing through the circulating fan 24 and enters the printing forming section 1.

[0100] Furthermore, the air outlet 25 is connected to the air outlet 19. The air outlet 25 is located on the upper rear side of the molding cavity of the printing molding section 1, and is located on the rear side of the frame 12. The outlet direction of the air outlet 25 faces the interior of the molding cavity of the printing molding section 1, and is used to blow clean air into the molding cavity. The air outlet 25 is located on the lower rear side of the galvanometer 17. The galvanometer 17 is located above the molding cavity of the printing molding section 1. The galvanometer 17 is fixed by the laser box 11 and the water cooling plate 31. The outlet of the air outlet 25 is located on the rear side of the galvanometer 17 and slightly lower than the horizontal plane of the galvanometer 17, which helps to avoid the wind field blowing directly towards the galvanometer 17 and prevent vibration or temperature fluctuations from affecting the precise control of the laser path.

[0101] The air inlet duct 21 is located at the lower front side of the molding cavity of the printing molding section 1, at the bottom front end of the frame 12, near the bottom of the observation window 4; the inlet direction of the air inlet duct 21 faces the interior of the molding cavity of the printing molding section 1, and is used to draw in air containing reaction products; the air inlet duct 21 is located in front of and below the galvanometer 17, forming a diagonal position with the air outlet duct 25.

[0102] The airflow direction is from the air outlet duct 25 to the air inlet duct 21, that is, from the upper rear side of the molding cavity of the printing molding section 1 to the lower front side, and the galvanometer 17 is disposed above the molding cavity of the printing molding section 1.

[0103] Furthermore, filter 23 uses a high-temperature resistant ceramic filter screen;

[0104] like Figure 5 As shown, the active cooling unit 3 includes a water-cooled plate housing 313 and a water inlet 311, a water outlet 312, a first water-cooled pipe 314, a second water-cooled pipe 315, and a temperature sensor channel 316 fixedly disposed on the water-cooled plate housing 313. The first water-cooled pipe 314 is connected to the second water-cooled pipe 315. The water inlet 311 and the water outlet 312 are respectively connected to the two ends of the first water-cooled pipe 314. The temperature sensor channel 316 is connected to the second water-cooled pipe 315.

[0105] Specifically, all pipelines in the circulating filtration part are made of stainless steel, an insulation layer is designed outside the stainless steel, and high-temperature-resistant asbestos sealing nets are used for sealing parts; high-temperature-resistant ceramic filter nets are used for filter nets, and the maximum temperature that can be withstood is 1200 DEG C.

[0106] Preferably, the filter 23 adopts 400-mesh, long-term temperature-resistant 800 DEG C alumina / silicon carbide ceramic filter nets, and the filter 23 selects 400-mesh (about 38 mu m aperture) as a balance point, which is a selection of excellent balance between filtering efficiency and system wind resistance, which can effectively capture most of the sub-micron to micron-sized smoke dust and aerosol particles generated in the high-temperature sintering process of SLS printing ceramics (such as SiC, Al2O3, ZrO2, etc.), and at the same time, it will not cause excessive pressure loss to the wind field, ensuring stable circulating air volume and good purging effect; the long-term temperature-resistant capability of 800 DEG C provides sufficient safety margin, ensuring the thermal stability and mechanical integrity of the filter 23 in the entire printing process, preventing cracking due to thermal stress, and the material is usually alumina or porous silicon carbide, which has such high-temperature performance.

[0107] The first water-cooled pipeline 314 is arranged in a snake shape on the water-cooled plate shell 313, and the pipe diameter of the second water-cooled pipeline 315 is different from that of the first water-cooled pipeline 314.

[0108] The present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application, and various changes and improvements can be made without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims.

Claims

1. A method of printing a ceramic structure with an SLS apparatus, characterized in that, Comprise: Step 1, the solvent evaporation method is prepared ceramic composite powder, ceramic powder, sintering aid and thermoplastic phenolic resin is mixed according to the proportion, add organic solvent ultrasonic dispersion uniform, after distillation, drying, grinding and screening, the thermoplastic phenolic resin uniform film ceramic composite powder with particle size distribution of 10~150 μm is obtained, wherein the volume ratio of ceramic powder and thermoplastic phenolic resin is (2~8):(2~8), the mass fraction of sintering aid is 3~15%; Step 2, start SLS ceramic high temperature 3D printing device, printing forming part (1), circulating filter part (2), air compressor and heating body assembly (13) and multi laser galvanometer unit are powered on in turn, the control program of SLS equipment starts self-checking, and the production environment, water, electricity and gas system and pipeline and auxiliary machine system are ensured to operate normally; Step 3, the control system of SLS equipment executes laser focusing program, and ensures that the laser focal point falls on the horizontal position of forming substrate; Step 4, powder adding, the ceramic composite powder prepared in step 1 is added to the powder feeding cylinder piston (16), and the adding amount reaches the predetermined standard; Step 5, roller (14) test, the roller (14) test program is executed in the control system of SLS equipment, and the forming cylinder piston (15) is pushed and the base layer powder is prepared; Step 6, the heating body assembly (13) is started in the control system of SLS equipment, the forming chamber is heated, and the forming substrate is preheated; Step 7, the wind field preheating program is executed in the control system of SLS equipment, and the air inlet and exhaust and wind field preheating are started; Step 8, when the temperature of the forming chamber reaches the predetermined sealing check threshold temperature, the component sealing check of SLS equipment is carried out; Step 9, after the sealing check is passed, the forming chamber heating is continued through the heating body assembly (13); Step 10, the forming chamber heating is completed through the heating control system in the forming chamber, and the temperature is kept at 500 DEG C by comprehensively controlling the wind field; Step 11, the laser device is started through the control system of SLS equipment, and the printing work is started in cooperation with the roller (14), the printing reaction product is swept to the air inlet pipeline by the wind field, enters the filter after the air inlet pipeline, filters out the reaction product, and the clean air after filtration is discharged from the air outlet after circulating through the circulating fan, enters the printing forming part (1), and realizes the circulating filtration; Step 12, after the printing manufacturing work is completed according to the control system program of SLS equipment, the laser device and the roller (14) are turned off, and the core mechanical components participating in the movement in the printing process are restored to the initial standby position; Step 13, the wind field preheating, substrate preheating and forming chamber heating are turned off, the temperature is gradually reduced to normal temperature by using the wind field; Step 14, the wind field is turned off, the active cooling part is turned off, the forming chamber door is opened, and the part is taken out, if subsequent processing is not needed, the SLS equipment is turned off, and cleaning and maintenance work is carried out.

2. The method of printing a ceramic structure with the SLS apparatus of claim 1, wherein, In step 6, the active cooling part (3) starts to cool the laser, galvanometer and sensor components at the same time when the heating body assembly preheating starts.

3. The method of printing a ceramic structure with the SLS apparatus of claim 1, wherein, In step 7, the direction of the air provided by the wind field is from the air outlet to the air inlet.

4. A SLS apparatus ceramic structure high temperature 3D printing device, characterized in that, The method for printing ceramic structure by the SLS device according to any one of claims 1 to 3 comprises the following steps: a printing forming part (1) is arranged for ceramic powder laying, printing and forming, wherein the printing forming part (1) is provided with a heating body assembly (13) for forming an ambient temperature of 500 DEG C or above in a forming cavity; an active cooling part (3) is arranged at the rear end of the printing forming part (1) for cooling the laser, galvanometer and sensor components; a circulating filtering part (2) is arranged at the rear end of the printing forming part (1) and the active cooling part (3) for filtering the reaction products of the ceramic printing process; an observation window (4) is arranged at the front end of the printing forming part (1) for observing the operation of the printing forming part.

5. The apparatus according to claim 4, wherein the ceramic structure is a ceramic structure for a SLS device. The printing forming part (1) comprises a laser box (11), a frame (12), a roller (14), a forming cylinder piston (15), a powder feeding cylinder piston (16), a galvanometer (17), a temperature sensor (18), an air outlet (19) and a water-cooled plate (31), the water-cooled plate (31) is fixedly installed above the frame (12), the laser box (11) is fixedly installed above the water-cooled plate (31), the galvanometer (17) is fixedly arranged at the laser outlet side of the laser box (11) to change the laser direction and control the laser path, the temperature sensor (18) is located above the inside of the frame (12) to monitor the temperature, the air outlet (19) is arranged at the rear side of the frame (12) to blow the circulating air, the forming cylinder piston (15) and the powder feeding cylinder piston (16) are arranged below the frame (12), the roller (14) is rollably arranged inside the frame (12) and rolls from the side of the powder feeding cylinder piston (16) to the side of the forming cylinder piston (15) to realize powder laying, the powder feeding cylinder piston (16) moves upward to feed powder before powder laying, the roller (14) moves from the side of the forming cylinder piston (15) back to the side of the powder feeding cylinder piston (16) to return to the original position after powder laying, then the laser starts to work, the laser path is controlled by the galvanometer (17), a layer of powder is sintered, the forming cylinder piston (15) moves downward after completion to leave space for the next layer of powder laying, and the process is repeated until the printing is completed.

6. The apparatus according to claim 4, wherein the ceramic structure is printed by a high temperature 3D printing device. The heating body assembly comprises an assembly shell, a thermocouple (136) and a heating rod (137) fixedly arranged on the assembly shell, and aerogel thermal insulation filled in the assembly shell, the heating directions of the thermocouple (136) and the heating rod (137) are opposite to the printed workpiece.

7. The SLS apparatus ceramic structure high temperature 3D printing device according to claim 6, characterized in that, The assembly shell comprises an upper cover plate (131), a lower cover plate (132), an inner cover plate (133), an outer cover plate (134) and a side cover plate (135), the inner cover plate (133) and the outer cover plate (134) are arranged in parallel, the upper cover plate (131) covers the upper side of the inner cover plate (133) and the outer cover plate (134), the lower cover plate (132) covers the lower side of the inner cover plate (133) and the outer cover plate (134), and the side cover plate (135) covers the side end of the inner cover plate (133) and the outer cover plate (134).

8. The apparatus according to claim 4, wherein the ceramic structure is printed by a high temperature 3D printing device. The circulation filtering part comprises an air inlet channel (21), a pipeline (22), a filter (23), a circulation fan (24) and an air outlet channel (25), the air inlet channel (21) is communicated with one end of the pipeline (22), the other end of the pipeline (22) is communicated with the inlet of the filter (23), the outlet of the filter (23) is communicated with the circulation fan (24), and the circulation fan (24) is communicated with the air outlet channel (25); after the circulation fan (24) is started, a pressure difference is formed between the air outlet channel (25) and the air inlet channel (21), an air field is generated in the printing forming part (1), the direction of the air field is from the air outlet channel (25) to the air inlet channel (21), the printing reaction product can be blown to the air inlet channel (21), enters the filter (23) after passing through the pipeline (22), and the reaction product is filtered out, and the clean air after filtration is discharged from the air outlet channel (25) again after passing through the circulation fan (24) and enters the printing forming part (1).

9. The apparatus according to claim 8, wherein the ceramic structure is a ceramic structure of a SLS device. The air outlet channel (25) is connected with the air outlet (19), the air outlet channel (25) is arranged on the upper part of the rear side of the forming cavity of the printing forming part (1) and is located on the rear side of the frame (12), the outlet direction of the air outlet channel (25) is towards the inside of the forming cavity of the printing forming part (1), and the clean air is blown into the forming cavity; The air outlet channel (25) is arranged below the rear side of the galvanometer (17), the galvanometer (17) is arranged above the forming cavity of the printing forming part (1), the galvanometer (17) is fixed through the laser box (11) and the water cooling plate (31), the outlet of the air outlet channel (25) is arranged on the rear side of the galvanometer (17) and is lower than the horizontal plane of the galvanometer (17), which helps to avoid the air field directly blowing to the galvanometer (17) and prevents the vibration or temperature fluctuation from affecting the accurate control of the laser path; The air inlet channel (21) is arranged on the lower part of the front side of the forming cavity of the printing forming part (1) and is located on the bottom of the front end of the frame (12) and is close to the lower side of the observation window (4); the inlet direction of the air inlet channel (21) is towards the inside of the forming cavity of the printing forming part (1), and the air containing the reaction product is sucked in; the air inlet channel (21) is located below the front side of the galvanometer (17) and forms a diagonal line with the air outlet channel (25); The direction of the air field flows from the air outlet channel (25) to the air inlet channel (21), that is, from the upper part of the rear side of the forming cavity of the printing forming part (1) to the lower part of the front side, and the galvanometer (17) is arranged above the forming cavity of the printing forming part (1).

10. The apparatus according to claim 8, wherein the ceramic structure is a ceramic structure of a SLS device. The filter (23) adopts a high-temperature-resistant ceramic filter screen; The active cooling part (3) comprises a water cooling plate shell (313), a water inlet (311), a water outlet (312), a first water cooling pipeline (314), a second water cooling pipeline (315) and a temperature sensor channel (316) fixedly arranged on the water cooling plate shell (313), the first water cooling pipeline (314) is communicated with the second water cooling pipeline (315), the water inlet (311) and the water outlet (312) are respectively communicated with two ends of the first water cooling pipeline (314), and the temperature sensor channel (316) is communicated with the second water cooling pipeline (315).

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