CN116512595A

CN116512595A - Polymer microwave sintering 3D printing forming process and device

Info

Publication number: CN116512595A
Application number: CN202310780525.0A
Authority: CN
Inventors: 朱伟; 姚洪波; 韩晓筱; 陈锋
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2023-06-29
Filing date: 2023-06-29
Publication date: 2023-08-01

Abstract

The invention relates to a polymer microwave sintering 3D printing forming process and a device, wherein the polymer microwave sintering 3D printing forming device comprises: a housing assembly; the forming platform is movably arranged on the shell component; a powder supply system for filling the polymer powder to the forming table and forming a polymer powder layer; a temperature control system for preheating the polymer powder; the microwave energy absorber spraying system is used for spraying the microwave energy absorber to the polymer powder; the microwave generation system is used for carrying out microwave sintering on the polymer powder; a power supply and a control system. The device disclosed by the application can form a single-layer polymer powder layer, a microwave energy absorber spraying system sprays a microwave absorbing medium on a designated area on the surface of the polymer powder, and a microwave generating system realizes powder sintering in a mode of selectively mixing and heating the polymer by microwave energy and realizes integral forming of parts by layer-by-layer sintering.

Description

Polymer microwave sintering 3D printing forming process and device

Technical Field

The invention relates to the technical field of additive manufacturing and forming, in particular to a polymer microwave sintering 3D printing and forming process and a device.

Background

Additive manufacturing, also known as 3D printing. The technique is to divide a three-dimensional model into a plurality of two-dimensional planes in a computer, and then stack the two-dimensional planes into a three-dimensional object by layer-by-layer shaping. This manufacturing method does not require an additional mold, and enables small-lot rapid manufacturing of objects having a complicated and fine structure in a short time.

Powder bed fusion is one of the mainstream polymer additive manufacturing technologies, which uses powder materials as raw materials, by laying a layer of polymer powder on the powder bed, and then using energy beams (such as laser beams, i.e. laser selective sintering technology) to selectively sinter and shape the powder along a preset path; the process of laying up the powder layer by layer and selectively sintering is then repeated, finally producing the target part. However, the following disadvantages still exist in the selective laser sintering forming mode: (1) Heating the powder material by a heat source such as a high-energy laser beam in a point-by-point or domain-by-domain mode, higher temperature gradient and thermal stress can be generated, and the part is difficult to warp, deform and form; (2) The heating time of the material in the high-speed scanning process is short, so that the requirements on the thermal property, rheological property and the like of the material are high, and the types of the polymer materials which can be used at present are few; (3) The point-by-point scanning forming efficiency is low, and the process parameters are complex; (4) The high quality lasers required are expensive, resulting in high machine costs. The above problems limit the wide application of polymer additive manufacturing techniques.

The microwave sintering is a new method for sintering material, and utilizes the special wave band of microwave to couple with basic microstructure of material to produce heat, and the dielectric loss of material can make its whole body be heated to sintering temperature so as to implement densification. The method has the characteristics of high heating speed, high energy utilization rate, small temperature gradient and the like; in addition, the microwave has the characteristic of selective heating, namely, the absorption of different materials and different relative microwaves is different, and the microwave can be divided into a microwave absorption material, a microwave reflection material and a microwave penetration material, so that the possibility of realizing selective microwave sintering 3D printing is provided.

Disclosure of Invention

Based on the above, it is necessary to provide a process and a device for microwave sintering and 3D printing of a polymer, which utilize the characteristics of low dielectric loss and transparent microwaves of the polymer based on the principle of microwave selective heating, spray a microwave absorbing medium with high dielectric loss on the surface of the polymer powder, realize sintering of the powder by means of selective mixed heating of the polymer by microwave energy, and realize forming of parts by layer-by-layer sintering. The technology has high forming efficiency and low cost, can manufacture parts with higher precision, more complex structure and better mechanical property, and has wider selection range of forming materials.

A polymeric microwave sintering 3D print forming apparatus comprising: the shell assembly is provided with a microwave cavity; the forming platform is movably arranged on the shell assembly and is positioned in the microwave cavity; a powder feed system disposed on the housing assembly, at least a portion of the powder feed system being located within the microwave cavity, the powder feed system for filling polymer powder to the forming platen and forming a polymer powder layer; a temperature control system disposed on the housing assembly, the temperature control system being located within the microwave cavity, the temperature control system being configured to preheat the polymer powder; the microwave energy absorber spraying system is arranged on the shell assembly, is positioned in the microwave cavity, is arranged opposite to the forming platform and is used for spraying the microwave energy absorber to polymer powder in a designated area; the microwave generation system is arranged on the shell assembly, is positioned in the microwave cavity, is arranged opposite to the forming platform and is used for carrying out microwave sintering on polymer powder absorbing the microwave energy absorber; the power supply and control system is arranged on the shell assembly and is electrically connected with the forming platform, the powder supply system, the temperature control system, the microwave energy absorber spraying system and the microwave generating system respectively.

In one embodiment, the forming platform is a forming piston cylinder, the forming piston cylinder comprises a first piston, a first guide rod assembly and a forming cylinder barrel, the forming cylinder barrel is provided with a first cavity, the first guide rod assembly is movably arranged on the forming cylinder barrel, the first guide rod assembly is positioned in the first cavity and is electrically connected with the power supply and the control system, the first piston is arranged on the first guide rod assembly, the first guide rod assembly can drive the first piston to reciprocate along the height direction of the forming cylinder barrel, the side wall of the first piston abuts against the inner wall of the forming cylinder barrel, the first piston and the end part of the forming cylinder barrel enclose to form a forming cavity, and the forming cavity is communicated with the microwave cavity.

In one embodiment, the first guide rod assembly comprises a first screw rod and a stepping motor, the stepping motor is electrically connected with the power supply and the control system, and the first screw rod is respectively in transmission connection with the first piston and the stepping motor.

In one embodiment, the powder feeding system comprises a powder feeding device and a powder spreading device, wherein the powder feeding device is arranged on the shell assembly and is used for conveying polymer powder to the forming platform, the powder spreading device is movably arranged on the shell assembly and can reciprocate relative to the forming platform, and the powder spreading device is used for flattening the polymer powder on the forming platform. In one embodiment, the powder feeding device comprises a powder feeding piston cylinder, the powder feeding piston cylinder comprises a powder feeding cylinder barrel, a second piston and a second guide rod assembly, the powder feeding cylinder barrel is arranged on the shell assembly, the powder feeding cylinder barrel is positioned in the microwave cavity, the powder feeding cylinder barrel is arranged adjacent to the forming platform, the powder feeding cylinder barrel is provided with a second cavity, the second guide rod assembly is arranged on the powder feeding cylinder barrel, the second guide rod assembly is positioned in the second cavity, the second guide rod assembly is electrically connected with the power supply and the control system, the second piston is arranged on the second guide rod assembly, the second guide rod assembly can drive the second piston to reciprocate along the height direction of the powder feeding cylinder barrel, the side wall of the second piston is propped against the inner wall of the forming cylinder barrel, the second piston and the end part of the powder feeding cylinder barrel enclose to form a first powder storage cavity, and the first powder storage cavity is communicated with the microwave cavity.

In one embodiment, the powder supply device comprises a powder leakage hopper, the powder leakage hopper is arranged on the shell assembly, the horizontal height of the powder leakage hopper is higher than that of the forming platform, the powder leakage hopper is provided with a second powder storage cavity, the powder leakage hopper faces one side of the forming platform, a powder outlet is formed in the second powder storage cavity, the second powder storage cavity can be communicated with the microwave cavity through the powder outlet, and the powder leakage hopper conveys polymer powder to the forming platform through the powder outlet.

In one embodiment, the number of the powder leakage hoppers is two, and the two powder leakage hoppers are respectively positioned at two sides of the forming platform.

In one embodiment, the powder spreading device comprises a powder spreading device, a first guide rail and a first driving assembly, wherein the first guide rail is arranged on the inner wall of the shell assembly, the first guide rail is opposite to the forming platform, the first driving assembly is arranged on the shell assembly or the first guide rail, the first driving assembly is electrically connected with the power supply and the control system, the powder spreading device is movably arranged on the first guide rail, the powder spreading device is positioned on one side close to the forming platform, the powder spreading device is in transmission connection with the first driving assembly, the first driving assembly drives the powder spreading device to reciprocate relative to the forming platform along the first guide rail, and the powder spreading device is used for leveling polymer powder on the forming platform.

In one embodiment, the first drive assembly includes a motor and a pulley.

In one embodiment, the powder spreader is a doctor blade or a roller, wherein the roller is driven to rotate by a motor.

In one embodiment, the temperature control system comprises a heating assembly and a temperature monitoring assembly, the heating assembly and the temperature monitoring assembly are both arranged on the shell assembly, the heating assembly and the temperature monitoring assembly are both positioned in the microwave cavity, the heating assembly and the temperature monitoring assembly are respectively and electrically connected with the power supply and the control system, and the temperature monitoring assembly is used for detecting temperature and feeding back temperature signals to the power supply and the control system.

In one embodiment, the number of heating elements is multiple.

In one embodiment, the number of temperature monitoring components is multiple.

In one embodiment, the heating device may be an infrared heating tube or a resistive heater.

In one embodiment, the heating device is an infrared heating lamp tube, and the infrared heating lamp tube is distributed above the forming cavity;

in one embodiment, the heating means is a resistive heater located at the bottom and around the forming piston cylinder.

In one embodiment, the temperature monitoring assembly is disposed above the forming chamber, the temperature monitoring assembly being configured to detect the machine ambient temperature and the temperature of the powder in the forming chamber.

In one embodiment, the microwave energy absorber spraying system comprises a liquid spraying assembly, a second guide rail and a second driving assembly, wherein the second guide rail is arranged on the inner wall of the shell assembly, the second guide rail is arranged opposite to the forming platform, the second driving assembly is arranged on the shell assembly or the second guide rail, the second driving assembly is electrically connected with the power supply and the control system, the liquid spraying assembly is movably arranged on the second guide rail, the liquid spraying assembly is positioned on one side close to the forming platform, the liquid spraying assembly is in transmission connection with the second driving assembly, the second driving assembly drives the liquid spraying assembly to reciprocate relative to the forming platform along the second guide rail, and the liquid spraying assembly is used for spraying the microwave energy absorber to polymer powder on the forming platform.

In one embodiment, the spray assembly comprises a spray head and a liquid supply box, the spray head is movably arranged on the second guide rail, the spray head is located on one side close to the forming platform, the spray head can reciprocate along the second guide rail relative to the forming platform, the liquid supply box is arranged on the spray head, the liquid supply box is provided with a liquid storage cavity, the liquid storage cavity is used for storing microwave energy absorbing agent, and the liquid storage cavity is communicated with the spray head.

In one embodiment, the second drive assembly includes a second drive motor drivingly connected to the spray assembly.

In one embodiment, the spray heads are nozzle modules arranged in an array, and the spray heads are piezoelectric or thermal bubble type.

In one embodiment, the number of spray assemblies is a plurality.

In one embodiment, the housing assembly is a metallic material.

In one embodiment, the microwave frequency of the microwave generating system is 300mhz to 300ghz.

In one embodiment, the device further comprises a powder collecting device, wherein the powder collecting device is arranged on the shell component and is positioned in the microwave cavity, the powder collecting device is adjacent to the forming platform or the powder feeding system and is provided with an opening, the powder collecting device is provided with a collecting cavity, the collecting cavity is communicated with the opening, and the powder collecting device is used for receiving and collecting redundant powder.

A second aspect of the present application discloses a polymeric microwave sintering 3D printing forming process.

A polymer microwave sintering 3D printing forming process is applied to the polymer microwave sintering 3D printing forming device, and comprises the following steps: s1: CAD model design and slicing treatment: designing a digital model of the workpiece by adopting CAD software, and obtaining two-dimensional section information of the workpiece by utilizing slicing software; s2: filling polymer powder: raising the forming table to a topmost position, the powder feed system filling the forming table with polymer powder; s3: preheating polymer powder: the temperature control system is started, and the temperature control system integrally heats the polymer powder in the forming platform and the powder supply system until the polymer powder on the forming platform is heated to a preset temperature; s4: laying single-layer powder: the forming platform is lowered by a corresponding height according to the preset thickness of the single-layer powder, and the powder supply system fills polymer powder into the forming platform and spreads the polymer powder to form a single-layer powder layer; s5: spraying a microwave energy absorber: determining a designated area of a single-layer powder layer according to the two-dimensional cross-section information of the workpiece, and spraying a microwave energy absorber to the designated area by the microwave energy absorber spraying system; s6: and (3) selectively sintering and forming a single powder layer by microwaves: starting a microwave generation system, and performing selective microwave sintering on the single-layer powder layer according to set power and time to finish forming a single-layer slice of the workpiece; s7: and (3) carrying out microwave sintering on the whole workpiece: repeating the steps S4 to S6 for a plurality of times until the sintering and forming of the powder at the last layer are completed; or repeating the steps S4 to S5 for forming a plurality of powder layers, then executing S6 to sinter and shape the part of the plurality of powder layers, and repeating the forming and sintering of the plurality of powder layers until the integral forming of the workpiece is completed.

In one embodiment, the polymer powder is a microwave transparent thermoplastic polymer material with low dielectric loss, and the thermoplastic polymer material comprises one or more of polypropylene, polyethylene, high density polyethylene, ultra-high molecular weight polyethylene, polytetrafluoroethylene, polystyrene, polysulfone, polyimide, polyaryletherketone, polyamide, polyoxymethylene, polycaprolactone, polylactic acid, thermoplastic polyurethane, and silicone rubber.

In one embodiment, the microwave energy absorber is a uniform mixture of a microwave absorbing material with high dielectric loss and a solvent, wherein the microwave absorbing material comprises one or more of carbon black, carbon nanotubes, graphene, quantum dots, micro-nano metal particles and micro-nano ceramic particles.

In one embodiment, the solvent in the microwave energy absorber comprises one or more of water, ethanol, methanol, propanol, isopropanol, acetone, methylene chloride, chloroform. Preferably, the solvent is water or ethanol.

In general, the above technical solutions conceived by the present invention, compared with the prior art, enable the following beneficial effects to be obtained:

(1) The selective microwave sintering 3D printing technology and the device adopt microwaves as energy, have high heating efficiency, uniform heating and small temperature gradient, are not easy to warp and deform, can greatly improve the forming efficiency and manufacture high-precision parts with complex structures.

(2) The invention combines the microwave transparent polymer powder and the microwave absorbing energy absorbing material, and can improve the precision of the formed parts.

(3) The invention can adopt the combination of a plurality of industrial ink-jet printing spray heads and the microwave energy absorbing agent storage cavity, and control the distribution of functional materials by conveying a plurality of functional materials so as to realize the manufacture of parts with complex functional requirements.

(4) The process can control the porosity distribution and mechanical property distribution of the workpiece by adjusting the content of the energy absorber in the single layer, and realize the manufacture of the functionally graded workpiece and the personalized workpiece.

(5) The invention can also sinter and shape the workpiece once, thus greatly reducing sintering time and processing energy loss.

(6) The process greatly reduces the performance requirement on the printing material, promotes the development speed of new materials in additive manufacturing, and has important significance for popularization of additive manufacturing technology.

Drawings

FIG. 1 is a schematic diagram of a polymer microwave sintering 3D printing forming apparatus of example 1;

FIG. 2 is a schematic diagram of a polymer microwave sintering 3D printing forming apparatus of example 2;

FIG. 3 is a schematic illustration of the operation of a powder bed surface and a plurality of sets of inkjet printheads;

FIG. 4 is a flow chart of a polymer microwave sintering 3D printing forming process;

fig. 5 is a scanning electron microscope image of a polymer microwave sintered product.

Wherein, the correspondence between the reference numerals and the component names is:

101 a microwave cavity, 1 a housing assembly;

201 forming cavity, 21 first piston, 22 first guide rod assembly, 23 forming cylinder;

301 a first powder storage cavity, 31 a powder supply cylinder barrel, 32 a second piston, 33 a second guide rod assembly, 34 a powder leakage hopper, 35 a powder spreader and 36 a first guide rail;

41 a heating assembly, 42 a temperature monitoring assembly;

51 spray heads, 52 liquid supply boxes and 53 second guide rails;

6, a microwave generating system;

7 a powder collection device;

10 powder bed surface, 20 molding zone, 30 absorber, 40 inkjet printhead array set, 50 microwave energy, 60 microwave generator.

Detailed Description

In order that the above-recited objects, features and advantages of the present invention will be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments may be combined with each other.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those described herein, and therefore the scope of the present invention is not limited to the specific embodiments disclosed below.

A polymer microwave sintering 3D printing forming apparatus according to some embodiments of the present invention is described below with reference to the accompanying drawings.

Example 1

As shown in fig. 1 and 2, the present embodiment discloses a polymer microwave sintering 3D printing forming apparatus, comprising: the microwave oven comprises a shell assembly 1, wherein a microwave cavity 101 is formed in the shell assembly 1; the forming platform is movably arranged on the shell assembly 1 and is positioned in the microwave cavity 101; a powder feeding system provided on the housing assembly 1, at least part of the powder feeding system being located within the microwave cavity 101, the powder feeding system being for filling the polymer powder to the forming table and forming a polymer powder layer; a temperature control system arranged on the shell assembly 1, the temperature control system being located in the microwave cavity 101, the temperature control system being used for preheating the polymer powder; the microwave energy absorber spraying system is arranged on the shell assembly 1, is positioned in the microwave cavity 101, is opposite to the forming platform and is used for spraying the microwave energy absorber to polymer powder in a designated area; the microwave generation system 6 is arranged on the shell assembly 1, the microwave generation system 6 is positioned in the microwave cavity 101, the microwave generation system 6 is arranged opposite to the forming platform, and the microwave generation system 6 is used for carrying out microwave sintering on polymer powder absorbing the microwave energy absorber; and the power supply and control system is arranged on the shell assembly 1 and is electrically connected with the forming platform, the powder supply system, the temperature control system, the microwave energy absorber spraying system and the microwave generating system 6 respectively.

The application discloses polymer microwave sintering 3D prints forming device is equipped with the shaping platform and can form individual layer polymer powder layer with powder feed system cooperation, based on the principle of microwave selective heating, utilizes polymer dielectric loss little, microwave transparent's characteristics, microwave energy absorber injection system sprays the microwave absorption medium that has high dielectric loss at polymer powder surface appointed region to carry out the mode of selective mixed heating to the polymer through microwave energy under the effect of microwave generation system 6 and realize the sintering of powder, and finally realize the integral shaping of part through the sintering layer upon layer. The device has high forming efficiency and low cost, can manufacture parts with higher precision, more complex structure and better mechanical property, and has wider selection range of forming materials.

As shown in fig. 1 and 2, this embodiment further defines, in addition to the features of the above-described embodiment: the forming platform is a forming piston cylinder, the forming piston cylinder comprises a first piston 21, a first guide rod assembly 22 and a forming cylinder barrel 23, the forming cylinder barrel 23 is provided with a first cavity, the first guide rod assembly 22 is movably arranged on the forming cylinder barrel 23, the first guide rod assembly 22 is positioned in the first cavity, the first guide rod assembly 22 is electrically connected with a power supply and a control system, the first piston 21 is arranged on the first guide rod assembly 22, the first guide rod assembly 22 can drive the first piston 21 to reciprocate along the height direction of the forming cylinder barrel 23, the side wall of the first piston 21 abuts against the inner wall of the forming cylinder barrel 23, the end part of the first piston 21 and the end part of the forming cylinder barrel 23 enclose to form a forming cavity 201, and the forming cavity 201 is communicated with the microwave cavity 101. Through adopting above-mentioned structure, first piston 21 encloses with the shaping cylinder and closes and form the shaping chamber and be used for receiving the polymer powder that powder feed system carried, and first piston 21 carries out elevating movement along the direction of height of shaping cylinder 23 under the drive of first guide arm subassembly 22 to make the laying of shaping platform matees powder feed system completion individual layer powder layer.

In addition to the features of the above embodiments, the present embodiment further defines: the first guide rod assembly 22 comprises a first screw rod and a stepping motor, the stepping motor is electrically connected with the power supply and the control system, and the first screw rod is respectively connected with the first piston 21 and the stepping motor in a transmission way. By adopting the structure, the stepping motor drives the first screw rod to move, so that the first piston 21 can realize up-and-down movement with extremely high precision under the drive of the first screw rod.

Preferably, the first piston 21 has a motion accuracy of + -10 μm.

As shown in fig. 1 and 2, this embodiment further defines, in addition to the features of the above-described embodiment: the powder supply system comprises a powder supply device and a powder spreading device, wherein the powder supply device is arranged on the shell assembly 1 and is used for conveying polymer powder to the forming platform, the powder spreading device is movably arranged on the shell assembly 1 and can reciprocate relative to the forming platform, and the powder spreading device is used for flattening the polymer powder on the forming platform. Through adopting above-mentioned structure, after the powder feeding device carries polymer powder to shaping platform, spread the powder device and carry out left and right sides reciprocating motion in shaping platform's top to promote polymer powder through spreading the powder device, thereby make the polymer powder on the shaping platform level and smooth, improve product structure precision from this.

As shown in fig. 1, this embodiment further defines, in addition to the features of the above-described embodiment: the powder feeding device comprises a powder feeding piston cylinder, the powder feeding piston cylinder comprises a powder feeding cylinder barrel 31, a second piston 32 and a second guide rod assembly 33, the powder feeding cylinder barrel 31 is arranged on the shell assembly 1, the powder feeding cylinder barrel 31 is positioned in the microwave cavity 101, the powder feeding cylinder barrel 31 is arranged adjacent to the forming platform, the powder feeding cylinder barrel 31 is provided with a second cavity, the second guide rod assembly 33 is arranged on the powder feeding cylinder barrel 31, the second guide rod assembly 33 is positioned in the second cavity, the second guide rod assembly 33 is electrically connected with a power supply and control system, the second piston 32 is arranged on the second guide rod assembly 33, the second guide rod assembly 33 can drive the second piston 32 to reciprocate along the height direction of the powder feeding cylinder barrel 31, the side wall of the second piston 32 abuts against the inner wall of the forming cylinder barrel 23, the second piston 32 is enclosed with the end part of the powder feeding cylinder barrel 31 to form a first powder storage cavity 301, and the first powder storage cavity 301 is communicated with the microwave cavity 101. Through adopting above-mentioned structure, second piston 32 encloses with powder feed cylinder 31 and closes and form first powder storage chamber 301 and be used for storing the polymer powder raw materials, and second piston 32 is followed the direction of height of shaping cylinder 23 and is risen under the drive of second guide arm assembly 33 to make polymer powder spill outside first powder storage chamber 301 by shop powder device propelling movement to the shaping platform, accomplish powder feeding work from this.

As shown in fig. 1 and 2, this embodiment further defines, in addition to the features of the above-described embodiment: the powder spreading device comprises a powder spreading device 35, a first guide rail 36 and a first driving assembly, wherein the first guide rail 36 is arranged on the inner wall of the shell assembly 1, the first guide rail 36 is arranged opposite to the forming platform, the first driving assembly is arranged on the shell assembly 1 or the first guide rail 36 and is electrically connected with a power supply and a control system, the powder spreading device 35 is movably arranged on the first guide rail 36, the powder spreading device 35 is positioned on one side close to the forming platform, the powder spreading device 35 is in transmission connection with the first driving assembly, the first driving assembly drives the powder spreading device 35 to reciprocate relative to the forming platform along the first guide rail 36, and the powder spreading device 35 is used for flattening polymer powder on the forming platform.

In addition to the features of the above embodiments, the present embodiment further defines: the first drive assembly includes a motor and a pulley. The powder spreader 35 is driven by a belt pulley driven by a motor to reciprocate left and right on the first guide rail 36.

In addition to the features of the above embodiments, the present embodiment further defines: the powder spreader 35 is a doctor blade or a roller, wherein the roller is driven to rotate by a motor.

As shown in fig. 1 and 2, this embodiment further defines, in addition to the features of the above-described embodiment: the temperature control system comprises a heating component 41 and a temperature monitoring component 42, wherein the heating component 41 and the temperature monitoring component 42 are arranged on the shell component 1, the heating component 41 and the temperature monitoring component 42 are both positioned in the microwave cavity 101, the heating component 41 and the temperature monitoring component 42 are respectively electrically connected with a power supply and a control system, and the temperature monitoring component 42 is used for detecting temperature and feeding back temperature signals to the power supply and the control system. By setting the temperature monitoring assembly 42, the temperature monitoring assembly 42 can detect the temperature of the powder in the forming cavity 201 and feed back to the power supply and control system, so that the power supply and control system can start heating or powder supply according to the temperature signal.

In addition to the features of the above embodiments, the present embodiment further defines: the number of heating elements 41 is plural.

In addition to the features of the above embodiments, the present embodiment further defines: the number of temperature monitoring components 42 is multiple.

In addition to the features of the above embodiments, the present embodiment further defines: the heating means may be an infrared heating lamp or a resistive heater. To uniformly heat the powder material in the forming chamber 201.

In addition to the features of the above embodiments, the present embodiment further defines: the heating device is an infrared heating lamp tube which is distributed above the forming cavity 201;

in addition to the features of the above embodiments, the present embodiment further defines: the heating device is a resistance heater, and the resistance heater is positioned at the bottom and around the forming piston cylinder.

In addition to the features of the above embodiments, the present embodiment further defines: a temperature monitoring assembly 42 is disposed above the forming chamber 201, the temperature monitoring assembly 42 being configured to detect the machine ambient temperature and the temperature of the powder in the forming chamber 201.

As shown in fig. 1 and 2, this embodiment further defines, in addition to the features of the above-described embodiment: the microwave energy absorber spraying system comprises a liquid spraying component, a second guide rail 53 and a second driving component, wherein the second guide rail 53 is arranged on the inner wall of the shell component 1, the second guide rail 53 is arranged opposite to the forming platform, the second driving component is arranged on the shell component 1 or the second guide rail 53 and is electrically connected with a power supply and a control system, the liquid spraying component is movably arranged on the second guide rail 53 and is positioned on one side close to the forming platform, the liquid spraying component is in transmission connection with the second driving component, the second driving component drives the liquid spraying component to reciprocate relative to the forming platform along the second guide rail 53, and the liquid spraying component is used for spraying microwave energy absorber to polymer powder on the forming platform. By adopting the structure, the second driving component drives the liquid spraying component to move to the corresponding position along the second guide rail 53 under the control of the power supply and the control system to spray the microwave energy absorbing agent to the polymer powder on the forming platform, so that the local spraying of the appointed area is realized.

As shown in fig. 1 and 2, this embodiment further defines, in addition to the features of the above-described embodiment: the spray assembly comprises a spray head 51 and a liquid supply box 52, wherein the spray head 51 is movably arranged on the second guide rail 53, the spray head 51 is positioned on one side close to the forming platform, the spray head 51 can reciprocate along the second guide rail 53 relative to the forming platform, the liquid supply box 52 is arranged on the spray head 51, the liquid supply box 52 is provided with a liquid storage cavity, the liquid storage cavity is used for storing microwave energy absorbing agent, and the liquid storage cavity is communicated with the spray head 51. By transporting multiple functional materials, the distribution of the functional materials is controlled to achieve fabrication of parts with complex functional requirements.

In addition to the features of the above embodiments, the present embodiment further defines: the second driving assembly comprises a second driving motor which is in transmission connection with the liquid spraying assembly.

In addition to the features of the above embodiments, the present embodiment further defines: the spray heads 51 are nozzle modules arranged in an array, and the spray heads 51 are piezoelectric or thermal bubble type.

In addition to the features of the above embodiments, the present embodiment further defines: the number of the liquid spraying components is plural.

In addition to the features of the above embodiments, the present embodiment further defines: the housing assembly 1 is made of a metal material. The microwave cavity 101 is a closed microwave resonant cavity composed of metal, so that uniformity of microwave wavelength in the cavity is ensured, and microwave leakage and discharge arc generation are prevented. Preferably, the housing assembly 1 is made of stainless steel material.

In addition to the features of the above embodiments, the present embodiment further defines: the microwave frequency of the microwave generating system 6 is 300 MHz-300 GHz.

Preferably 433MHz,915MHz,2450MHz,5800MHz,22121MHz,28000MHz. Further preferably 2450MHz.

As shown in fig. 1 and 2, this embodiment further defines, in addition to the features of the above-described embodiment: still include powder collection device 7, powder collection device 7 sets up on casing subassembly 1, and powder collection device 7 is located microwave cavity 101, and powder collection device 7 is equipped with the opening with shaping platform or powder feed system adjacent setting, powder collection device 7, and powder collection device 7 is equipped with the collection chamber, and the collection chamber communicates with the opening, and powder collection device 7 is used for accepting and collecting unnecessary powder.

Example 2

As shown in fig. 2, the structure of the powder supplying device in this embodiment is different from that of the powder supplying device in the foregoing embodiment, and the other structures are the same, in this embodiment, the powder supplying device includes a powder leaking hopper 34, the powder leaking hopper 34 is disposed on the housing assembly 1, the level of the powder leaking hopper 34 is higher than that of the forming platform, the powder leaking hopper 34 is provided with a second powder storage cavity (not shown), a powder outlet is provided on one side of the powder leaking hopper 34 facing the forming platform, the second powder storage cavity is communicated with the microwave cavity 101 through the powder outlet, and the powder leaking hopper 34 conveys polymer powder to the forming platform through the opening and closing powder outlet. By adopting the structure, the power supply and the control system can control the opening and closing size and the opening and closing time length of the powder outlet of the powder leakage hopper 34, so as to realize quantitative conveying of polymer powder.

In addition to the features of the above embodiments, the present embodiment further defines: the number of the powder leakage hoppers 34 is two, and the two powder leakage hoppers 34 are respectively positioned at two sides of the forming platform. Through the arrangement of the first driving assembly, the powder spreader 35 can reciprocate along the first guide rail 36 under the drive of the first driving assembly, and polymer powder is pushed by the powder spreader 35, so that the polymer powder on the forming platform is flat.

Example 3

As shown in fig. 4, this embodiment will take polycaprolactone material as an example to provide a polymer microwave sintering 3D printing forming process:

(1) CAD model design and slicing treatment: designing a digital model of the workpiece by adopting CAD software, and obtaining two-dimensional section information of the workpiece by utilizing slicing software;

(2) Filling polymer powder: raising the forming table to a topmost position, the powder supply system filling the forming table with polymer powder;

(3) Preheating polymer powder: starting a temperature control system, wherein the temperature control system integrally heats polymer powder in the forming platform and the powder supply system until the polymer powder on the forming platform is heated to 50-54 ℃, preferably 51 ℃;

(4) Laying single-layer powder: the forming platform descends by 0.1mm, the powder supply system fills polymer powder into the forming platform and spreads the polymer powder to form a single powder layer, and the redundant powder is collected by the powder collecting cavity;

(5) Spraying a microwave energy absorber: determining a designated area of a single-layer powder layer according to the two-dimensional section information of the workpiece, enabling the spray head to move along the second guide rail, and spraying 0.2% carbon nano tube alcohol dispersion liquid to the designated area on the polycaprolactone powder layer by controlling the opening and closing of the spray head;

(6) And (3) selectively sintering and forming a single powder layer by microwaves: starting a microwave generation system, setting power to 1200W for 30s, and performing selective microwave sintering on the single-layer powder layer, wherein polymer powder in a region without spraying a microwave energy absorber is not sintered due to transparency to microwaves, so that forming of a single-layer slice of a workpiece is completed;

(7) And (3) carrying out microwave sintering on the whole workpiece: repeating steps S4 to S6 for a plurality of times until the sintering and forming of the powder of the last layer are completed.

Example 4

As shown in fig. 4, this embodiment takes polypropylene material as an example, and provides a polymer microwave sintering 3D printing forming process:

(3) Preheating polymer powder: starting a temperature control system, wherein the temperature control system integrally heats the polymer powder in the forming platform and the powder supply system until the polymer powder on the forming platform is heated to 160-170 ℃, preferably 165 DEG C

(4) Laying single-layer powder: the forming platform descends to a height of 0.1mm, the powder supply system fills polymer powder into the forming platform and spreads the polymer powder to form a single powder layer, and the excessive powder is collected by the powder collecting cavity;

(5) Spraying a microwave energy absorber: and determining a designated area of the single-layer powder layer according to the two-dimensional section information of the workpiece, wherein two groups of spray heads and liquid supply boxes respectively carrying 0.2% carbon nano tube alcohol dispersion liquid and 5% hydroxyapatite alcohol dispersion liquid move along a second guide rail, and spraying the two materials to the designated area on the polypropylene powder layer by controlling the on-off state and the on-off state of the spray heads, wherein the hydroxyapatite dispersion liquid can realize functionality.

(6) Preforming a workpiece: and (5) repeating the steps (4) and (5), paving 10 layers, and spraying the 0.2% carbon nano tube alcohol dispersion liquid and the 5% hydroxyapatite alcohol dispersion liquid to finish the partial preforming of the workpiece.

(7) Forming a workpiece part: the microwave generating system is started, the power and the time are set to 1200W and 100s, and the selective microwave sintering is carried out.

(8) And (3) carrying out microwave sintering on the whole workpiece: repeating the steps (6) and (7) until the integral forming of the workpiece is completed.

Firstly, the interior of a microwave cavity is raised to a certain temperature, then a layer of polymer matrix material is paved on a forming platform, then a microwave energy absorbing agent spraying system can selectively spray energy absorbing material on the polymer material layer on a preset path, then a microwave generating system emits microwaves, the energy absorbing material can absorb microwave energy to sinter polymer powder, and the above operation is repeated until a workpiece is formed. The invention can manufacture the workpiece with customizable material distribution, and the function of the workpiece is customized in a personalized way. In the whole process of the printing technology, the three-dimensional model (STL) of the workpiece and the subsequent slicing treatment are performed by computer software, and the moving part and the temperature control are controlled by a computer numerical control system.

From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

In addition to the features of the above embodiments, the present embodiment further defines: the polymer powder is a microwave transparent thermoplastic high polymer material with low dielectric loss, and the thermoplastic high polymer material comprises one or more of polypropylene, polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene, polytetrafluoroethylene, polystyrene, polysulfone, polyimide, polyaryletherketone, polyamide, polyoxymethylene, polycaprolactone, polylactic acid, thermoplastic polyurethane and silicone rubber.

In addition to the features of the above embodiments, the present embodiment further defines: the microwave energy absorber is a uniform mixture composed of a microwave absorbing material with high dielectric loss and a solvent, and the microwave absorbing material comprises one or a combination of more of carbon black, carbon nano tubes, graphene, quantum dots, micro-nano metal particles and micro-nano ceramic particles.

In addition to the features of the above embodiments, the present embodiment further defines: the solvent in the microwave energy absorber comprises one or more of water, ethanol, methanol, propanol, isopropanol, acetone, methylene dichloride and chloroform.

As shown in fig. 5, polycaprolactone is used as polymer powder, a microwave energy absorber is a mixture of carbon nanotubes and ethanol, the polymer is subjected to microwave sintering and 3D printing by the method to form a product, and the product is subjected to electron microscope scanning to obtain a scanning electron microscope image.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims

1. A polymeric microwave sintering 3D print forming apparatus comprising:

the microwave oven comprises a shell assembly (1), wherein the shell assembly (1) is provided with a microwave cavity (101);

the forming platform is movably arranged on the shell assembly (1) and is positioned in the microwave cavity (101);

a powder feeding system provided on the housing assembly (1), at least part of the powder feeding system being located within the microwave cavity (101), the powder feeding system being for filling polymer powder to the forming table and forming a polymer powder layer;

a temperature control system provided on the housing assembly (1), the temperature control system being located within the microwave cavity (101), the temperature control system being for preheating polymer powder;

The microwave energy absorber spraying system is arranged on the shell assembly (1), is positioned in the microwave cavity (101), is arranged opposite to the forming platform and is used for spraying the microwave energy absorber to polymer powder in a designated area;

the microwave generation system (6) is arranged on the shell assembly (1), the microwave generation system (6) is positioned in the microwave cavity (101), the microwave generation system (6) is arranged opposite to the forming platform, and the microwave generation system (6) is used for carrying out microwave sintering on polymer powder absorbing a microwave energy absorber;

the power supply and control system is arranged on the shell assembly (1) and is electrically connected with the forming platform, the powder supply system, the temperature control system, the microwave energy absorber spraying system and the microwave generating system (6) respectively.

2. The polymer microwave sintering 3D printing forming device according to claim 1, characterized in that the forming platform is a forming piston cylinder, the first piston (21) cylinder comprises a first piston (21), a first guide rod assembly (22) and a forming cylinder (23), the forming cylinder (23) is provided with a first cavity, the first guide rod assembly (22) is movably arranged on the forming cylinder (23), the first guide rod assembly (22) is positioned in the first cavity, the first guide rod assembly (22) is electrically connected with the power supply and the control system, the first guide rod assembly (21) is arranged on the first guide rod assembly (22), the first guide rod assembly (22) can drive the first piston (21) to reciprocate along the height direction of the forming cylinder (23), the side wall of the first piston (21) is propped against the inner wall of the forming cylinder (23), the first piston (21) and the end part of the forming cylinder (23) form a forming cavity (201), and the forming cavity (201) is communicated with the microwave cavity (101).

3. The polymer microwave sintering 3D printing forming device according to claim 1, wherein the powder feeding system comprises a powder feeding device and a powder spreading device, the powder feeding device is arranged on the shell assembly (1), the powder feeding device is used for conveying polymer powder to the forming platform, the powder spreading device is movably arranged on the shell assembly (1), the powder spreading device can reciprocate relative to the forming platform, and the powder spreading device is used for flattening the polymer powder on the forming platform.

4. The polymeric microwave sintering 3D printing forming apparatus of claim 3, wherein,

the powder feeding device comprises a powder feeding piston cylinder, the powder feeding piston cylinder comprises a powder feeding cylinder barrel (31), a second piston (32) and a second guide rod assembly (33), the powder feeding cylinder barrel (31) is arranged on the shell assembly (1), the powder feeding cylinder barrel (31) is positioned in the microwave cavity (101), the powder feeding cylinder barrel (31) is arranged adjacent to the forming platform, the powder feeding cylinder barrel (31) is provided with a second cavity, the second guide rod assembly (33) is arranged on the powder feeding cylinder barrel (31), the second guide rod assembly (33) is positioned in the second cavity, the second guide rod assembly (33) is electrically connected with the power supply and control system, the second piston (32) is arranged on the second guide rod assembly (33), the second guide rod assembly (33) can drive the second piston (32) to reciprocate along the height direction of the powder feeding cylinder barrel (31), the side wall of the second piston (32) is in contact with the inner wall (23) of the forming cavity (301), and the second guide rod assembly (33) is in electrical connection with the microwave cavity (301) and the end part of the second piston (31) is in contact with the microwave cavity (301); and/or

The powder supply device comprises a powder leakage hopper (34), the powder leakage hopper (34) is arranged on the shell assembly (1), the horizontal height of the powder leakage hopper (34) is higher than that of the forming platform, the powder leakage hopper (34) is provided with a second powder storage cavity, a powder outlet is formed in one side of the powder leakage hopper (34) facing the forming platform, the second powder storage cavity can be communicated with the microwave cavity (101) through the powder outlet, and the powder leakage hopper (34) conveys polymer powder to the forming platform through opening and closing the powder outlet; and/or

The powder spreading device comprises a powder spreading device (35), a first guide rail (36) and a first driving assembly, wherein the first guide rail (36) is arranged on the inner wall of the shell assembly (1), the first guide rail (36) is arranged opposite to the forming platform, the first driving assembly is arranged on the shell assembly (1) or the first guide rail (36), the first driving assembly is electrically connected with a power supply and a control system, the powder spreading device (35) is movably arranged on the first guide rail (36), the powder spreading device (35) is positioned on one side close to the forming platform, the powder spreading device (35) is in transmission connection with the first driving assembly, the first driving assembly drives the powder spreading device (35) to reciprocate relative to the forming platform along the first guide rail (36), and the powder spreading device (35) is used for flattening polymer powder on the forming platform.

5. The polymer microwave sintering 3D printing forming device according to claim 1, wherein the temperature control system comprises a heating component (41) and a temperature monitoring component (42), wherein the heating component (41) and the temperature monitoring component (42) are both arranged on the shell component (1), the heating component (41) and the temperature monitoring component (42) are both positioned in the microwave cavity (101), the heating component (41) and the temperature monitoring component (42) are respectively electrically connected with the power supply and the control system, and the temperature monitoring component (42) is used for detecting temperature and feeding back a temperature signal to the power supply and the control system.

6. The polymer microwave sintering 3D printing forming device according to claim 1, wherein the microwave energy absorber spraying system comprises a spraying component, a second guide rail (53) and a second driving component, the second guide rail (53) is arranged on the inner wall of the shell component (1), the second guide rail (53) is arranged opposite to the forming platform, the second driving component is arranged on the shell component (1) or the second guide rail (53), the second driving component is electrically connected with the power supply and the control system, the spraying component is movably arranged on the second guide rail (53), the spraying component is positioned on one side close to the forming platform, the spraying component is in transmission connection with the second driving component, and the second driving component drives the spraying component to reciprocate along the second guide rail (53) relative to the forming platform, and the spraying component is used for spraying the microwave energy absorber to polymer powder on the forming platform.

7. The polymeric microwave sintering 3D printing forming apparatus of claim 1, wherein,

the shell component (1) is made of metal materials; and/or

The microwave frequency of the microwave generating system (6) is 300 MHz-300 GHz.

8. The polymer microwave sintering 3D printing forming device according to claim 1, further comprising a powder collecting device (7), the powder collecting device (7) being arranged on the housing assembly (1), the powder collecting device (7) being located in the microwave cavity (101), the powder collecting device (7) being arranged adjacent to the forming table or the powder feeding system, the powder collecting device (7) being provided with an opening, the powder collecting device (7) being provided with a collecting cavity, the collecting cavity being in communication with the opening, the powder collecting device (7) being adapted to receive and collect excess powder.

9. A polymer microwave sintering 3D printing forming process applied to the polymer microwave sintering 3D printing forming device according to any one of claims 1-8, comprising the following steps:

s1: CAD model design and slicing treatment: designing a digital model of the workpiece by adopting CAD software, and obtaining two-dimensional section information of the workpiece by utilizing slicing software;

S2: filling polymer powder: raising the forming table to a topmost position, the powder feed system filling the forming table with polymer powder;

s3: preheating polymer powder: the temperature control system is started, and the temperature control system integrally heats the polymer powder in the forming platform and the powder supply system until the polymer powder on the forming platform is heated to a preset temperature;

s4: laying single-layer powder: the forming platform is lowered by a corresponding height according to the preset thickness of the single-layer powder, and the powder supply system fills polymer powder into the forming platform and spreads the polymer powder to form a single-layer powder layer;

s5: spraying a microwave energy absorber: determining a designated area of a single-layer powder layer according to the two-dimensional cross-section information of the workpiece, and spraying a microwave energy absorber to the designated area by the microwave energy absorber spraying system;

s6: and (3) selectively sintering and forming a single powder layer by microwaves: starting a microwave generating system (6), and performing selective microwave sintering on the single-layer powder layer according to set power and time to finish forming of single-layer slices of the workpiece;

s7: and (3) carrying out microwave sintering on the whole workpiece: repeating the steps S4 to S6 for a plurality of times until the sintering and forming of the powder at the last layer are completed; or repeating the steps S4 to S5 for forming a plurality of powder layers, then executing S6 to sinter and shape the part of the plurality of powder layers, and repeating the forming and sintering of the plurality of powder layers until the integral forming of the workpiece is completed.

10. The polymer microwave sintering 3D printing forming process according to claim 9, wherein,

the polymer powder is a microwave transparent thermoplastic high polymer material with low dielectric loss, and the thermoplastic high polymer material comprises one or more of polypropylene, polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene, polytetrafluoroethylene, polystyrene, polysulfone, polyimide, polyaryletherketone, polyamide, polyoxymethylene, polycaprolactone, polylactic acid, thermoplastic polyurethane and silicone rubber; and/or

The microwave energy absorber is a uniform mixture composed of a microwave absorbing material with high dielectric loss and a solvent, wherein the microwave absorbing material comprises one or more of carbon black, carbon nano tubes, graphene, quantum dots, micro-nano metal particles and micro-nano ceramic particles, and the solvent in the microwave energy absorber comprises one or more of water, ethanol, methanol, propanol, isopropanol, acetone, dichloromethane and chloroform.