Multi-material 3D printing device based on photo-thermal coupling effect and forming method thereof

Abstract

The invention discloses a multi-material 3D printing device based on a photo-thermal coupling effect and a forming method of the multi-material 3D printing device, and relates to the field of additive manufacturing. The light source device is a semicircular convergent photo-thermal emitting device, 360-degree light source irradiation can be achieved, and illumination is uniform. After the slurry is extruded, the ultraviolet curing process can be immediately carried out, and the phenomenon that a printed entity collapses due to the influence of gravity factors caused by untimely light source irradiation can be obviously reduced. By adjusting the frequency and duty ratio of the light source, the temperature and illumination intensity of the slurry in the extrusion device are adjusted, so that the slurry is easier to extrude and form, and the formation of a hyperfine structure is realized; and a multi-axis moving platform is adopted, so that multi-angle complex structural parts can be easily formed. The extrusion device is used as a core, and high integration of the printing device is achieved. The printing efficiency is greatly improved, ultrahigh-precision and ultrahigh-height printing of a complex structure is achieved, and the problems of collapse caused by gravity factors and difficulty in forming a high-precision structural part are solved.

Description

Technical Field

[0001] The invention relates to the technical field of additive manufacturing, and is a multi-material 3D printing device based on photothermal coupling. Background Art

[0002] Ink direct writing technology is an additive manufacturing technology that solidifies and forms by extruding slurry and stacking it. It has the advantages of low cost and fast manufacturing speed. At the same time, the deposited sample can be used as a support to achieve a printing process without auxiliary support. When manufacturing parts, this technology can use high-viscosity ceramic slurry for printing, and the solid content of the slurry can exceed 50vol%, so that the manufactured parts have a higher theoretical density and excellent mechanical properties. This is the advantage of ink direct writing technology in manufacturing ceramic parts;

[0003] However, the practice of using the printed sample as a support during the printing process of ink direct writing technology will undoubtedly cause uneven force between the layers, and the ink direct writing forming and printing curing mechanism makes it unable to immediately have sufficient support capacity, resulting in deformation problems of each layer due to different forces in Z-axis printing. The shortcomings of ink direct writing technology in printing accuracy have always been a focus of attention. The improvement of its printing accuracy can greatly help its forming performance of complex structural parts.

[0004] UV curing is a curing method that utilizes free radical photopolymerization. When ultraviolet light irradiates the slurry, the chromophore of the photoinitiator in the slurry absorbs ultraviolet energy and becomes excited, thereby generating a large number of free radicals, which polymerize the resin monomers. It has rapid curing characteristics and certain mechanical properties. The printed layer can provide good support for the layer to be printed.

[0005] There are existing tracking light sources and point light source irradiation devices. Among them, the tracking light source device has a single irradiation direction, and considering the blockage of the nozzle, there is a time delay between the slurry extrusion and the light curing, which makes the slurry unable to cure immediately, thus causing many problems; the point light source irradiation device can provide continuous irradiation of a light source in a specific direction, but this will cause the remaining backlight directions to have poor light quality, resulting in reduced forming accuracy. Summary of the invention

[0006] In order to solve the above problems, the present invention innovates and improves the existing equipment and slurry curing system, and provides a multi-material 3D printing device based on photothermal coupling to improve the instant curing performance and printing accuracy of ink direct writing technology printing, and enhance its ability to construct complex structures.

[0007] The design scheme adopted by the present invention is: a multi-material 3D printing device based on light-heat coupling. It includes:

[0008] Multi-axis mobile platform;

[0009] The extrusion device respectively penetrates the concentric fixing hole of the extrusion device and the light-heat coupling device. The tip of the extrusion device is provided with a light-proof nozzle to prevent the nozzle from being blocked by ultraviolet light curing, thereby ensuring the smooth extrusion and forming of the slurry filaments. The end of the extrusion device is a power device to provide power for the slurry extrusion;

[0010] The concentric fixing hole of the extrusion device is installed on the multi-axis moving platform and has a concentric hole with the extrusion device. The extrusion device is fastened to ensure that it does not move due to a small external force and is used to fix the end of the extrusion device;

[0011] The photothermal coupling device is installed on the extrusion device, has a concentric hole with the extrusion device, and is used to fasten the extrusion device. It has a focusing heat collecting cover. The light source is evenly distributed on the inner wall of the focusing heat collecting cover with the central axis of the extrusion device as the center. The uneven arrangement will cause the light and heat to fail to accurately irradiate the tip of the extrusion device, thereby causing uneven forming and collapse, and even clogging of the nozzle, and failure to print normally. The irradiated light is evenly concentrated on the tip of the extrusion device. The light source and the focusing heat collecting cover can heat, keep warm and solidify the extruded slurry. The heating function can enable the slurry to be extruded and formed normally, otherwise the slurry will be difficult to extrude and cannot be printed;

[0012] In a possible implementation, the multi-axis mobile platform has no less than three axes;

[0013] In one possible implementation, the extrusion device, barrel and nozzle have light-shielding capabilities, and the light-shielding method is one or more of spraying, coating, and light-shielding material extrusion devices, to prevent ultraviolet light curing from clogging the nozzle, thereby ensuring that the slurry filaments are extruded and formed smoothly;

[0014] In one possible implementation, the extrusion device is fixed with a concentric fixing hole, and the extrusion device is fixed on the multi-axis moving platform. As the multi-axis moving platform moves, there is no obvious relative movement between the three. Elastomers, rigid bodies, threaded holes and matching screws can be used for fastening;

[0015] In a possible implementation, the photothermal coupling device can be fastened by an elastic body or a rigid body and fixed on the extrusion device, with the printing plane as the reference surface, and the edge of the focusing heat collecting cover of the photothermal coupling device is 0-35mm higher than the tip of the extrusion device and lower than the concentric fixing hole of the extrusion device;

[0016] In a possible implementation, the photothermal coupling device is characterized in that it is powered by a DC regulated power supply;

[0017] In a possible implementation, the light-heat coupling device uses a PWM controller to adjust the light frequency and duty cycle;

[0018] In a possible implementation, the photothermal coupling device uses a PWM signal amplification module to amplify the electrical signal;

[0019] In one possible implementation, the photothermal coupling device has a light-collecting cover with evenly distributed lamp beads of no less than two, which are used to emit ultraviolet light beams to solidify the slurry filaments extruded from the nozzle and to heat and keep the slurry in the extrusion device warm.

[0020] In a possible implementation, the ultraviolet light initiation system slurry has the following composition of the mass fractions of the materials in the slurry:

[0021] Photosensitive resin: 15%-30%;

[0022] Photoinitiator: 0.3%-2.5%;

[0023] Rheology modifier: 1%-5%;

[0024] Main material: 65%-80%;

[0025] In a possible implementation, the photosensitive resin is one or a combination of polyester acrylate, trimethylolpropane triacrylate, polyurethane acrylate, 1,6-hexanediol diacrylate, and tripropylene glycol diacrylate;

[0026] The photoinitiator is one or a combination of camphorquinone, 1-phenyl-1,2-propanedione, dichlorotantalum, biscyclopentadienyl [2,6-difluoro-3-(1-pyrrolyl)phenyl]titanium, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide;

[0027] The rheology modifier is one or a combination of nano silicon dioxide, BYK-111, BYK-410, BYK-333, nano kaolin clay, and graphene;

[0028] The main material is one or a combination of alumina, zirconium oxide, silicon nitride, nylon, polytetrafluoroethylene, polyetheretherketone, silicon oxide, lead zirconate titanate, barium titanate, and hydroxyapatite;

[0029] In a possible implementation, the forming method specifically comprises the following steps: S1 importing the model data in STL format into the slicing software;

[0030] S2 sets the printing parameters in the slicing software, and then performs slicing. The slicing software is Cura, Simplify 3D, Slic3r, and EasyPrint 3D. The Gcode format file is obtained and converted into the robot arm command, which is then imported into the device.

[0031] S3 adjusts the extrusion pressure of the extrusion power device so that the extrusion device can smoothly extrude the slurry;

[0032] S4 adjusts the light frequency and duty cycle of the photothermal coupling device so that the extruded slurry filaments can be cured normally;

[0033] S5 performs 3D printing;

[0034] The beneficial effects of the present invention are: (1) the use of a multi-axis mobile platform can easily realize the forming of multi-angle complex structural parts, which is conducive to the forming of large overhang angles and complex curved thin-wall structures;

[0035] (2) During the printing process, after the slurry is squeezed out of the nozzle, the light source is immediately irradiated for photopolymerization. The fast curing speed allows the slurry to be instantly cured at the moment of extrusion and provides sufficient support for the upper layer printing;

[0036] (3) Control of the light frequency and duty cycle allows the device to continue printing for a long time without being unable to continue printing due to nozzle clogging caused by over-curing;

[0037] (4) The photothermal coupling device has heat collection and insulation functions, which can heat and insulate the extruder. For high-viscosity resin system slurry, it can be thinned by heating, which is conducive to the printing of high-precision complex structural parts with small-diameter nozzles. It can reduce internal gaps to form high-density parts, which is conducive to the widespread application of direct writing printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings are for detailed description of the components in the following embodiments to facilitate understanding;

[0039] A multi-material 3D printing device based on photothermal coupling comprises a five-axis moving platform 1, a concentric fixing hole 2 of an extrusion device, a photothermal coupling device 3 and an extrusion device 4;

[0040] Figure 1 A schematic structural diagram of a five-axis mobile platform 1 and a concentric fixing hole 2 of an extrusion device of a multi-material 3D printing device based on light-heat coupling in an embodiment provided by the present invention;

[0041] Figure 2 A schematic diagram of the structure of a photothermal coupling device 3 and an extrusion device 4 of a multi-material 3D printing device based on photothermal coupling in an embodiment of the present invention;

[0042] Figure 3 The sintered part in Example 1 provided by the present invention; Figure 4 The sintered part in Example 2 provided by the present invention; Figure 5 The sintered part in Example 3 provided by the present invention;

[0043] Five-axis mobile platform 1; A axis 11; B axis 12; C axis 13; D axis 14; E axis 15; deposition forming platform 16;

[0044] Extrusion device concentric fixing hole 2;

[0045] Photothermal coupling device 3; power supply 31; PWM controller and PWM signal amplification module 32; focusing heat collecting cover 33; ultraviolet light source 34; concentric fixing hole 35; optical frequency and duty cycle adjustment knob 36; wire 37;

[0046] Extrusion device 4; air pipe 41; piston 42; slurry 43; nozzle 44; slurry filament 45; DETAILED DESCRIPTION Example 1

[0047] The present invention is described in detail below in conjunction with specific embodiments. The description in this section is only exemplary and explanatory. The described embodiments are only part of the embodiments of the present application, not all of the embodiments, and should not have any limiting effect on the scope of protection of the present invention.

[0048] The present application is further described below in conjunction with the accompanying drawings and embodiments.

[0049] Figure 1 An exemplary embodiment of the present invention is shown, which is a schematic structural diagram of a five-axis mobile platform and a concentric fixed hole of an extrusion device. Figure 2 The schematic diagram of the structure of the power supply, PWM controller, PWM signal amplification module, light-collecting heat collecting cover and extrusion device of an exemplary embodiment of the present invention is shown. The multi-material 3D printing device based on the light-heat coupling effect includes: a five-axis moving platform 1, a concentric fixing hole 2 of the extrusion device, a light-heat coupling device 3 and an extrusion device 4.

[0050] In an embodiment of the present invention, a five-axis mobile platform 1 is involved to realize position movement during printing. It is a commonly used industrial equipment, an ink direct writing forming device based on a fully rotating five-axis robotic arm, and multi-scale manufacturing of structural parts is realized through spatial posture control. It adopts a five-degree-of-freedom serial rotating axis configuration. The end effector can reach any posture in the global workspace through kinematic positive solution. It includes a base, shafts and connecting rods, a driver and a reducer, a sensor system and a controller. The base, shafts and connecting rods are made of steel or aluminum alloy, and the driver usually adopts a servo motor or a stepper motor. The machine provides the power for the shaft rotation. The reducer usually adopts a harmonic reducer or a planetary reducer to amplify the torque and improve the motion accuracy. The rotation angle and limit information of each axis are fed back through the sensor system. The trajectory is controlled by the PLC core for printing. In this embodiment, the active angle range of each axis of the five-axis mobile platform 1 is 360° for the A axis 11, 270° for the B axis 12, 180° for the C axis 13, 180° for the D axis 14, and 360° for the E axis 15. The maximum speed is 240° / s, and the 3D printing accuracy is ±0.05mm.

[0051] In detail, Figure 1 In the embodiment, the present invention comprises: an A axis 11, a B axis 12, a C axis 13, a D axis 14, an E axis 15 and a deposition forming platform 16;

[0052] In the embodiment of the present invention, the extrusion device concentric fixing hole 2 is fixed on the five-axis mobile platform 1 without relative movement; the extrusion device 4 passes through the extrusion device concentric fixing hole 2, and the extrusion device concentric fixing hole 2 is turned outward 90° along the tangent at the opening, and is made of elastomeric material PLA3D printing, which can clamp the extrusion device 4;

[0053] In the embodiment of the present invention, the photothermal coupling device 3 is composed of the following parts: a power supply 31, a PWM controller and a PWM signal amplifying module 32, a light-collecting cover 33, an ultraviolet light source 34, a concentric fixing hole 35, and a wire 37; the light-collecting cover 33 and the ultraviolet light source 34 chimera are installed and fixed on the extrusion device 4 through the concentric fixing hole 35 through the extrusion device 4, and the edge of the light-collecting cover 33 and the ultraviolet light source 34 chimera of the photothermal coupling device 3 is 15mm higher than the tip of the extrusion device with the printing plane as the reference surface; the PWM controller and the PWM signal amplifying module 32 can be freely adjusted, the corresponding light frequency adjustment range is 0Hz-99kHz, and the corresponding duty cycle adjustment range is 0-100%, and the photothermal effect of the ultraviolet light source 34 is adjusted, and the power supply 31, the PWM controller and the PWM signal amplifying module 32 and the ultraviolet light source 34 are connected by a wire 37;

[0054] In the embodiment of the present invention, the ultraviolet light source 34 is composed of 24 LED lamp beads connected in series, the voltage range of the lamp beads is 2.8-3.6V, and the center of the extrusion device 4 is taken as the center of the circle, and the ultraviolet light source 34 is evenly distributed on the inner wall of the focusing heat collecting cover 33. The focusing heat collecting cover 33 collects the heat and light emitted by the ultraviolet light source 34. Figure 2 The lower edge of the combined body of the light-collecting and heat-collecting cover 33 and the ultraviolet light source 34 can normally collect light and heat and print at a distance of 10 mm from the nozzle;

[0055] In the embodiment of the present invention, the extrusion device 4 passes through the concentric fixing hole 2 and the concentric fixing hole 35 of the extrusion device, and the position of the extrusion device 4 can be adjusted up and down. The air pipe 41 provides pressure to push the piston 42 and then push the slurry 43. The slurry 43 passes through the nozzle 44, accompanied by the focusing heat collecting cover 33 and the ultraviolet light source 34 mosaic to provide temperature and light source irradiation for the slurry 43 in the extrusion device, and is extruded into slurry filaments 45, and then the five-axis mobile platform controls the displacement to form a 3D printed part. The nozzle 44 is also concentric with the extrusion device 4.

[0056] In this embodiment, the slurry is a UV-initiated system slurry, and the composition of the mass fractions of the various materials in the slurry is as follows:

[0057] Photosensitive resin: 23%;

[0058] Photoinitiator: 1.5%;

[0059] Rheology modifier: 2%;

[0060] Zirconia powder: 73.5%;

[0061] The above are the components of the ultraviolet light initiation system slurry, wherein:

[0062] The photosensitive resin is polyester acrylate, trimethylolpropane triacrylate, and 1,6-hexanediol diacrylate in a mass ratio of 1:2:1, accounting for 23% of the slurry mass.

[0063] The photoinitiator is camphorquinone, biscyclopentadienyl [2,6-difluoro-3-(1-pyrrolyl)phenyl] titanium, and (2,4,6-trimethylbenzoyl) diphenylphosphine oxide in a mass ratio of 1:1:1, and the total accounts for 1.5% of the slurry mass;

[0064] The rheology modifiers are nano-silica, BYK-111, and titanium dioxide in a mass ratio of 4:2:1, accounting for 2% of the slurry mass;

[0065] The main material is zirconium oxide powder with a median particle size D50 of 1 μm, accounting for 73.5% of the total mass of the slurry;

[0066] After the materials are prepared, the slurry is prepared, that is, the various components of the slurry are placed in a slurry tank according to the proportion. First, the resin is injected into the slurry tank, and the rheology modifier and the photoinitiator are added. The slurry is placed in a centrifugal homogenizer and centrifuged at a speed of 1800r / min for homogenization. The main material zirconium oxide powder is added in small amounts and multiple times, and the single addition amount is 80% of the total mass of the resin. After each addition, the slurry is centrifuged at a speed of 2000r / min for homogenization. After the last centrifugal homogenization, the slurry is vacuum defoamed in the centrifugal homogenizer;

[0067] Next, the forming method flow is explained.

[0068] Place the slurry after centrifugal homogenization in the extrusion device 4, put in the piston 42, select the nozzle 44 according to the size and accuracy of the printed part, and in this embodiment, the diameter of the nozzle 44 is 0.2 mm. Insert the extrusion device 4 into the concentric fixing hole 2 of the extrusion device, fix the extrusion device 4 on the five-axis mobile platform 1, apply pressure to the piston through the air pipe 41 to push the slurry 43 out of the nozzle 44, and adjust the slurry extrusion speed by adjusting the air pressure in the air pipe 41. In this embodiment, the adjusted air pressure is 70 psi;

[0069] The light-collecting cover 33 and the ultraviolet light source 34 in the photothermal coupling device 3 are installed and fixed on the extrusion device 4 through the concentric fixing hole 35 through the extrusion device 4, and the slurry filament 45 is extruded at a given air pressure in the air pipe 41. The light frequency and duty cycle adjustment knob 36 of the PWM controller 32 are adjusted to control the light source, and the voltage of the power supply 31 is adjusted to 76V for printing. In this embodiment, the light frequency is set to 12kHz and the duty cycle is 60%, wherein the light frequency refers to the number of times the light pulse signal recurs per unit time, which is the key to the forming quality. A lower light frequency will cause ripples and a small part of the printed surface to collapse, and a higher light frequency will cause the printed part to be over-exposed to light, resulting in increased brittleness and lower toughness; the duty cycle refers to the proportion of the power-on time to the total time in a pulse cycle, which is the key to continuous printing. A lower duty cycle will cause a large area of ​​the printed part to collapse, so that the printed part cannot be self-supporting, and thus cannot be continuously printed. A higher duty cycle will cause the nozzle to be blocked during the printing process, so that it cannot be continuously printed.

[0070] Import the model data in STL format into the slicing software;

[0071] Set the printing parameters in the slicing software, set the trajectory speed to 10mm / s, set the layer height to 0.15mm, and slice after the parameters are set. The slicing software is Cura, Simplify 3D, Slic3r, EasyPrint 3D, obtain the Gcode format file, convert it into a robot arm command through the 'gcode_milling' package of ROS, import it into the device for printing, and obtain the part blank, which is a printed part without degreasing or sintering;

[0072] Place the green body in a drying oven, adjust the drying temperature to 100°C, and dry it for 10 hours until the moisture disappears;

[0073] After putting the dried blank into the crucible, put the crucible into the atmosphere degreasing furnace, close the furnace cover, use a vacuum pump to evacuate the atmosphere degreasing furnace to negative pressure, ensure that the absolute pressure in the atmosphere degreasing furnace is ≤45.7KPa, and close the exhaust valve; fill argon as a protective gas, and open the exhaust valve when the pressure in the furnace reaches an absolute pressure of 23.7KPa; the gas from the atmosphere degreasing furnace is discharged into the chemical waste gas absorption liquid through the air pipe to prevent environmental pollution; set the degreasing temperature, first increase it from room temperature to 350℃ at a rate of 0.2℃ / min, keep it warm for 30min, then increase it to 700℃ at a rate of 0.3℃ / min, keep it warm for 30min, and finally cool it with the furnace; click Run to start degreasing in the atmosphere degreasing furnace, and after degreasing is completed, the parts are taken out after cooling with the furnace;

[0074] Put the debinded parts into the sintering furnace, close the furnace door, set the decarburization and sintering temperatures, and perform decarburization and sintering; first, increase the temperature from room temperature to 600°C at a rate of 0.4°C / min, keep it for 60 minutes, then increase it to 1500°C at a rate of 0.5°C / min, keep it for 60 minutes, and finally cool it with the furnace;

[0075] The sintered parts were taken out, and the wall thickness of the parts was 0.11-0.14mm. The shrinkage rates of the samples after sintering were 27.3% in the X-axis direction, 28.4% in the Y-axis direction, and 28.2% in the Z-axis direction. Figure 3 The height of the sample on the left side of the middle is 60 mm after sintering, and there is no collapse in the Z-axis direction of the sample; Example 2

[0076] This embodiment is different from the first embodiment. It adopts a three-axis translation mobile platform. The three-axis translation mobile platform is a device that can achieve high-precision linear motion in three orthogonal directions of X, Y, and Z. Its core components include: a drive system, which usually adopts a servo motor or a stepper motor to provide a power source; a transmission mechanism, which usually adopts a precision screw or gear to convert the rotational motion of the motor into a linear displacement, with a sensitivity of up to 0.01mm and a translation speed range of 1-120mm / s; a guide system, which usually adopts a linear guide rail or a ball bearing to ensure the linear accuracy and stability of the motion trajectory; a measurement system for real-time feedback of displacement data; a skeleton structure, which usually adopts steel or aluminum alloy to provide support for the drive system, the transmission system, and the guide system; a control system, which is programmed through a PLC or an embedded controller and controls the path trajectory through Gcode to achieve automated motion of complex paths;

[0077] It has the same concentric fixing hole of the extrusion device as in Example 1, which is used to fix the extrusion device 4, extrude the slurry filament 45, and form a 3D printing model by layer-by-layer trajectory accumulation accompanied by the chimera of the focusing heat collecting cover 33 and the ultraviolet light source 34;

[0078] In this embodiment, the slurry is a UV-initiated system slurry, and the composition of the mass fractions of the various materials in the slurry is as follows:

[0079] Photosensitive resin: 17%;

[0080] Photoinitiator: 0.3%;

[0081] Rheology modifier: 2.7%;

[0082] Alumina powder: 80%;

[0083] The above are the components of the ultraviolet light initiation system slurry, wherein:

[0084] The photosensitive resin is composed of three materials: polyurethane acrylate, polyester acrylate, and 1,6-hexanediol diacrylate in a mass ratio of 1:4:1, which accounts for 17% of the slurry mass.

[0085] The photoinitiator is 1-phenyl-1,2-propanedione, dichlorobis(pentadienyl)titanium, and bis(cyclopentadienyl)[2,6-difluoro-3-(1-pyrrolyl)phenyl]titanium in a mass ratio of 2:1:1, and the total accounts for 0.3% of the slurry mass;

[0086] The rheology modifiers are BYK-410, BYK-111, and graphene in a mass ratio of 1:5:1, accounting for 2.7% of the slurry mass;

[0087] The main material is alumina powder with a median particle size D50 of 3 μm, accounting for 80% of the total mass of the slurry;

[0088] After the materials are prepared, the slurry is prepared, that is, the various components of the slurry are placed in a slurry tank according to the proportion. First, the resin is injected into the slurry tank, and the rheology modifier and the photoinitiator are added. The slurry is placed in a centrifugal homogenizer and centrifuged at a speed of 1800r / min for homogenization. The main material zirconium oxide powder is added in small amounts and multiple times, and the single addition amount is 80% of the total mass of the resin. After each addition, the slurry is centrifuged at a speed of 2000r / min for homogenization. After the last centrifugal homogenization, the slurry is vacuum defoamed in the centrifugal homogenizer;

[0089] Then, the forming method flow is described;

[0090] Place the slurry after centrifugal homogenization in the extrusion device 4, put in the piston 42, select the nozzle 44 according to the size and accuracy of the printed part, and in this embodiment, the diameter of the nozzle 44 is 0.2 mm. Insert the extrusion device 4 into the concentric fixing hole 2 of the extrusion device, fix the extrusion device 4 on the five-axis mobile platform 1, apply pressure to the piston through the air pipe 41 to push the slurry 43 out of the nozzle 44, and adjust the slurry extrusion speed by adjusting the air pressure in the air pipe 41. In this embodiment, the adjusted air pressure is 78 psi;

[0091] The light-collecting cover 33 and the ultraviolet light source 34 in the photothermal coupling device 3 are installed and fixed on the extrusion device 4 through the concentric fixing hole 35 through the extrusion device 4, and the slurry filament 45 is extruded according to the air pressure in the air pipe 41, and the light frequency and duty cycle adjustment knob 36 of the PWM controller 32 are adjusted to control the light source, and the voltage of the power supply 31 is adjusted to 76.5V for printing. In this embodiment, the light frequency is set to 20kHz and the duty cycle is set to 75%;

[0092] Import the model data in STL format into the slicing software for printing to obtain the blank;

[0093] Set the printing parameters in the slicing software, set the trajectory speed to 8mm / s, set the layer height to 0.15mm, and slice after the parameters are set. The slicing software is Cura, Simplify 3D, Slic3r, EasyPrint 3D, obtain the Gcode format file, import it into the device for printing, and obtain the part blank, which is a printed part without degreasing or sintering;

[0094] The rest of the work process is the same as in Example 1;

[0095] After sintering, the parts were taken out. The shrinkage rates of the samples after sintering were 10.0% in the X-axis direction, 9.9% in the Y-axis direction, and 11.1% in the Z-axis direction. The size of the samples after sintering was 38.2*5.2*3.1mm, and the three-point bending strength was 185MPa. Example 3

[0096] In this embodiment, the slurry is a UV-initiated system slurry, and the composition of the mass fractions of the various materials in the slurry is as follows:

[0097] Photosensitive resin: 30%;

[0098] Photoinitiator: 0.7%;

[0099] Rheology modifier: 4.5%;

[0100] Zirconia doped lead zirconate titanate powder: 64.8%;

[0101] The above are the components of the ultraviolet light initiation system slurry, wherein:

[0102] The photosensitive resin is composed of three materials: polyurethane acrylate, tripropylene glycol diacrylate and trimethylolpropane triacrylate in a mass ratio of 2:1:3, which accounts for 30% of the slurry mass.

[0103] The photoinitiator is 1-phenyl-1,2-propanedione and 2,4,6-trimethylbenzoyl)diphenylphosphine oxide in a mass ratio of 2:1, accounting for 0.7% of the slurry mass.

[0104] The rheology modifiers are nano-silica, BYK-333, and nano-kaolin clay in a mass ratio of 2:1:1, accounting for 4.5% of the slurry mass;

[0105] The main material is zirconium oxide doped lead zirconate titanate powder, wherein the median particle size D50 of the zirconium oxide powder is 1 μm, the median particle size D50 of the lead zirconate titanate is 150 nm, the mass ratio of zirconium oxide to lead zirconate titanate is 15:1, accounting for 64.8% of the total mass of the slurry;

[0106] After the materials are prepared, the slurry is prepared, that is, the various components of the slurry are placed in a slurry tank according to the proportion. First, the resin is injected into the slurry tank, and the rheology modifier and the photoinitiator are added. The slurry is placed in a centrifugal homogenizer and centrifuged at a speed of 1800r / min for homogenization. The main material zirconium oxide powder is added in small amounts and multiple times, and the single addition amount is 80% of the total mass of the resin. After each addition, the slurry is centrifuged at a speed of 2000r / min for homogenization. After the last centrifugal homogenization, the slurry is vacuum defoamed in the centrifugal homogenizer;

[0107] Then, the forming method flow is explained.

[0108] Place the slurry after centrifugal homogenization in the extrusion device 4, put in the piston 42, select the nozzle 44 according to the size and accuracy of the printed part, and in this embodiment, the diameter of the nozzle 44 is 0.2 mm. Insert the extrusion device 4 into the concentric fixing hole 2 of the extrusion device, fix the extrusion device 4 on the five-axis mobile platform 1, apply pressure to the piston through the air pipe 41 to push the slurry 43 out of the nozzle 44, and adjust the slurry extrusion speed by adjusting the air pressure in the air pipe 41. In this embodiment, the adjusted air pressure is 55 psi;

[0109] The light-collecting cover 33 and the ultraviolet light source 34 in the photothermal coupling device 3 are installed and fixed on the extrusion device 4 through the concentric fixing hole 35 through the extrusion device 4, and the slurry filament 45 is extruded according to the air pressure in the air pipe 41, and the light frequency and duty cycle adjustment knob 36 of the PWM controller 32 are adjusted to control the light source, and the power supply 31 voltage is adjusted to 78V for printing. In this embodiment, the light frequency is set to 40kHz and the duty cycle is set to 25%;

[0110] Import the model data in STL format into the slicing software for printing to obtain the blank;

[0111] Set the printing parameters in the slicing software, set the trajectory speed to 15mm / s, set the layer height to 0.15mm, and slice after the parameters are set. The slicing software is Cura, Simplify 3D, Slic3r, EasyPrint 3D, obtain the Gcode format file, import it into the device for printing, and obtain the part blank, which is a printed part without degreasing or sintering;

[0112] The rest of the workflow is the same as in Example 2;

[0113] After sintering, take out the parts. Figure 5 The sintered samples of this embodiment have shrinkage rates of 33.1% in the X-axis direction, 33.3% in the Y-axis direction, and 35.1% in the Z-axis direction. The relative density of the sintered samples is 91.7%, and the truss structure has no deformation or collapse.

[0114] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-material 3D printing device based on photothermal coupling, characterized in that: include: Multi-axis mobile platform; The extrusion device has a light-proof nozzle at the tip to prevent the nozzle from being blocked by UV curing, and a power device at the end to provide power for slurry extrusion; The concentric fixing hole of the extrusion device is installed on the multi-axis moving platform and is used to fix the extrusion device; The photothermal coupling device is fixed on the extrusion device and has a focusing heat collecting cover. The light source is distributed on the inner wall of the focusing cover, and the irradiated light is concentrated on the tip of the extrusion device; a PWM controller is used to adjust the light frequency and duty cycle.

2. The multi-material 3D printing device based on light-heat coupling according to claim 1, characterized in that: The multi-axis mobile platform has no less than three axes.

3. The multi-material 3D printing device based on light-heat coupling according to claim 1, characterized in that: The extrusion device, the barrel and the nozzle light-shielding method prevent ultraviolet light curing from clogging the nozzle, ensuring the extrusion of the slurry filaments; the extrusion power device is one or a combination of pneumatic extrusion power devices, electric extrusion power devices, and magnetic extrusion power devices.

4. The multi-material 3D printing device based on light-heat coupling according to claim 1, characterized in that: The extrusion device is fixed on the multi-axis moving platform through the concentric fixing hole of the extrusion device, and moves with the multi-axis moving platform.

5. The multi-material 3D printing device based on light-heat coupling according to claim 1, characterized in that: The photothermal coupling device is fixed on the extrusion device, with the printing plane as the reference surface, and the edge of the light-collecting heat collecting cover of the photothermal coupling device is higher than the tip of the extrusion device and lower than the concentric fixing hole of the extrusion device.

6. The multi-material 3D printing device based on light-heat coupling according to claim 1, characterized in that: The photothermal coupling device adopts a PWM signal amplification module to amplify the electrical signal.

7. The multi-material 3D printing device based on light-heat coupling according to claim 1, characterized in that: In the photothermal coupling device, the lamp beads in the light-collecting and heat-collecting cover are evenly distributed on the inner wall of the light-collecting and heat-collecting cover with the central axis of the extrusion device as the center, and the number of the lamp beads is not less than two.

8. The multi-material 3D printing device based on light-heat coupling according to claim 1, characterized in that: The slurry used is a UV-initiated system slurry, and the composition of the mass fractions of the various materials in the slurry is as follows: Photosensitive resin: 15%-30%; Photoinitiator: 0.3%-2.5%; Rheology modifier: 1%-5%; Main material: 62.5%-80%.

9. The slurry used in the multi-material 3D printing device based on light-heat coupling according to claim 8, characterized in that: The photosensitive resin is one or a combination of polyester acrylate, polyurethane acrylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, and tripropylene glycol diacrylate; The photoinitiator is one or a combination of camphorquinone, 1-phenyl-1,2-propanedione, dichlorotantalum, biscyclopentadienyl [2,6-difluoro-3-(1-pyrrolyl)phenyl]titanium, (2,4,6-trimethylbenzoyl) diphenylphosphine oxide; The rheology modifier is one or a combination of nano-silicon dioxide, BYK-111, BYK-410, BYK-333, nano-kaolin clay, and graphene; The main material is one or a composite of alumina, zirconium oxide, silicon nitride, nylon, polytetrafluoroethylene, polyetheretherketone, silicon oxide, lead zirconate titanate, barium titanate, and hydroxyapatite.

10. A forming method using a multi-material 3D printing device based on light-heat coupling as claimed in claim 1, characterized in that include: S1 imports the model data in STL format into the slicing software; S2 sets the printing parameters in the slicing software, and then performs slicing. The slicing software is Cura, Simplify3D, Slic3r or EasyPrint 3D. The slicing file is obtained and imported into the printing device. S3 adjusts the extrusion pressure of the extrusion power device to extrude the slurry; S4 adjusts the light-heat coupling device to allow the extruded slurry filaments to be solidified; S5 is 3D printed.

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