WO2023029209A1

WO2023029209A1 - Method and device for low-pressure 3d printing of high-performance polymers and composites thereof

Info

Publication number: WO2023029209A1
Application number: PCT/CN2021/129414
Authority: WO
Inventors: 田小永; 张明杰; 刘腾飞; 康友伟
Original assignee: 西安交通大学
Priority date: 2021-08-28
Filing date: 2021-11-08
Publication date: 2023-03-09
Also published as: CN113733555A

Abstract

A method and device for the low-pressure 3D printing of high-performance polymers and composites thereof. The device comprises a control cabinet (1) and a low-pressure forming chamber (4); the control cabinet (1) comprises a control panel (2) and a vacuum pump (3); the control panel (2) comprises low-pressure forming chamber air pressure control, temperature control, printhead temperature control, heating platform temperature control and motion control; the vacuum pump (3) extracts air from the low-pressure forming chamber (4); the low-pressure forming chamber (4) comprises an air inlet valve (5), a sensor (6), a radiation heating lamp tube (7) and a heating platform (8), and the heating platform (8) is porous and is used in cooperation with a sand blasting PEI thin film. The method comprises: after the control panel (2) sets a target pressure value of the low-pressure forming chamber (4), the vacuum pump (3) extracting air in the low-pressure forming chamber (4) to form a vacuum environment; and using the control panel (2) to set required low-pressure forming chamber temperature, printhead temperature, etc., and completing a 3D printing forming process in the low-pressure forming chamber (4). The method realizes the manufacturing of 3D fabricated parts of high-performance polymers and composites thereof having high interlayer bonding strength, high crystallinity and small warpage deformation.

Description

A low-pressure 3D printing method and device for high-performance polymers and their composite materials

technical field

The invention belongs to the technical field of additive manufacturing, and in particular relates to a method and device for low-pressure 3D printing of high-performance polymers and their composite materials.

Background technique

High-performance polymers such as PE, PPS, PEI, PEKK, PAEK, PEEK, etc. and their fiber-reinforced composite materials have typical characteristics such as high melting temperature, high melt viscosity, and crystallization during the forming process, making their 3D printing process difficult , The requirements for forming equipment are strict, and the forming process faces the problems of poor interlayer bonding performance, serious warping deformation, and difficult control of polymer crystallinity.

In order to improve the problem of poor interlayer bonding, two methods of physical and chemical modification were proposed. Among them, physical methods often use various preheating devices such as infrared and laser to re-preheat the accumulated polymer on the previous layer during printing to reduce the temperature difference between layers and increase the bonding strength between layers. However, due to the limited preheating time of this method, the demand for heating power is huge, and laser heaters generally belong to local heating, which will also cause serious local temperature distribution differences during the heating process, and problems such as the generation of interlayer stress cannot be effectively avoided; while chemical The way of modification is currently very limited to increase the bonding strength between layers, and most of them are still in the stage of scientific research, and large-scale industrial applications cannot be realized yet;

In order to solve the serious problem of warping and deformation, a controlled cold deposition 3D printing process is proposed, which mainly uses forced convection to instantly cool the high-temperature polymer melt extruded from the nozzle outlet during the forming process. Reducing the temperature gradient between layers avoids the generation of internal stress between layers, and can also prevent the crystallization of polymers and reduce the internal stress of crystallization, thereby reducing the warping and deformation of parts. However, this method will greatly reduce the crystallinity of parts. Its mechanical properties often cannot meet the application requirements in aerospace and other fields, and generally can only be used in medical and health fields. For this reason, a heat treatment technology for this process is proposed. After the 3D printing is completed, the material is tempered, annealed, etc. Treatment can recrystallize the workpiece, but the degree of crystallization is generally limited, and the shrinkage and deformation of the workpiece cannot be controlled, and the processing cost is also greatly increased;

In order to improve the crystallinity of 3D printing high-performance thermoplastic polymers and their composite materials, high-temperature 3D printing is currently the most used method, adding a high-temperature environment cavity to the 3D printing device, and forcing the 3D printing sample to be heated through the ambient temperature to make the polymerization The material is always kept at a high temperature, which can not only reduce the temperature gradient between the layers of the workpiece, improve the interlayer bonding performance, but also reduce the generation of interlayer internal stress. At the same time, the long-term high temperature state can ensure that the polymer molecules are fully arranged to obtain high Therefore, high-temperature 3D printing is a comprehensive technical means, and it has a relatively good effect on improving many problems faced by high-performance polymers. At this time, the temperature requirements for the environmental cavity are generally relatively high, and the ideal environmental cavity The temperature should be above the glass transition temperature of the polymer and below the melting temperature, which puts forward very strict requirements for the forming equipment. It needs to have a good insulation system, and the power consumption of the equipment is very large, but most of the heat is eventually dissipated to the air. This method poses relatively high challenges to equipment durability and process controllability.

In summary, the current 3D printing of high-performance thermoplastic polymers and their composites has a short time in the high-temperature state during the forming process, and the interlayer bonding and crystallization process is insufficient, and the temperature gradient itself is large, and there is a large internal stress. The existing methods are difficult to effectively solve the above shortcomings of the forming process.

Contents of the invention

In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method and device for low-pressure 3D printing of high-performance polymers and their composite materials, which can achieve high-performance interlayer bonding strength, high crystallinity, and small warpage deformation. Manufacture of polymer and its composite 3D parts.

In order to achieve the above object, the present invention takes the following technical solutions:

A high-performance polymer and its composite material low-pressure 3D printing device, including a control cabinet 1 and a low-pressure forming chamber 4, the control cabinet 1 and the low-pressure forming chamber 4 are electrically connected through a control bus 12;

The control cabinet 1 includes a control panel 2 and a vacuum pump 3; the control panel 2 includes a low pressure forming chamber air pressure control part, a low pressure forming chamber temperature control part, a print head temperature control part, a heating platform 8 temperature control part and a motion control part , the control bus 12 is connected to the control panel 2 on the upper part of the control cabinet 1 through the aviation plug 11 on the inner wall of the low-pressure forming chamber 4; the vacuum pump 3 is located below the control cabinet 1, and the vacuum pump 3 is connected to the low-pressure forming chamber 4 through a sealed pipe 13 , extracting air from the low-pressure forming chamber 4 to provide a low-pressure forming environment.

The low-pressure forming chamber 4 includes an air intake valve 5, a sensor 6, a radiation heating lamp 7, a heating platform 8, and an aviation plug 11; the air intake valve 5 is located outside the low-pressure forming chamber 4 and communicates with the internal and external environments for balancing Internal and external pressure difference; the sensor 6 is located inside the low-pressure forming chamber 4, and is responsible for feeding back the temperature and pressure inside the low-pressure forming chamber 4; the radiation heating lamp tubes 7 are evenly distributed on the inner wall of the low-pressure forming chamber 4, and the heating platform 8 adopts a separate connection method Placed in the low pressure forming chamber 4.

The bottom of the heating platform 8 is provided with a shock-absorbing foot pad, which reduces vibration transmission during the printing process.

The heating platform 8 has a porous feature and is used with a sandblasting PEI film.

The print head in the low-pressure forming chamber 4 is divided into two types: one is a single material inlet print head 9-1, which is made of pure resin filament, short fiber reinforced resin filament or continuous fiber reinforced resin prepreg filament. One of them is the raw material, which is used to manufacture pure resin and its composite material parts. At this time, the corresponding materials used are pure polymer material\prepreg material 10-1, pure polymer material\prepreg material 10-1 from a single material The upper part of the inlet print head 9-1 penetrates; the other is the dual-material inlet in-situ impregnation print head 9-2, which uses continuous fiber filaments and resin filaments as raw materials to manufacture composite material parts. The materials are fiber material 10-2 and pure polymer material 10-3, the fiber material 10-2 penetrates from above the in-situ dipping print head 9-2 at the dual material inlet, and the pure polymer material 10-3 penetrates from the dual material inlet The side penetration of the in-situ dip printhead 9-2.

Both print heads are connected with a typical XYZ type motion mechanism and are provided with motion; the parts of the stepper motor, ball screw and limit switch in a typical XYZ type motion mechanism should use vacuum stepper motors, vacuum lead screws and vacuum Parts of fiber switches adapted to low-voltage environments.

The high-performance polymer and its composite material low-pressure 3D printing device is used to produce polymer and its composite material parts that require high crystallinity and interlayer bonding strength, and can also be used as a ground verification experiment platform for additive manufacturing in space environments.

A method for utilizing a high-performance polymer and its composite material low-pressure 3D printing device, comprising the following steps:

1) After setting the target pressure value of the low-pressure forming chamber 4 through the control panel 2, the vacuum pump 3 extracts the air in the low-pressure forming chamber 4 through the sealed hose 13 to provide a low-pressure environment for the low-pressure forming chamber 4; when the target pressure value is low enough , the low pressure forming chamber 4 is in a vacuum environment;

2) Use the control panel 2 to set the required low-pressure forming chamber temperature, print head temperature, and heating platform 8 temperature, and select the required motion code to control the typical XYZ-type motion mechanism to move, and complete 3D in the low-pressure forming chamber 4 Printing and forming process; during the printing process, the temperature and pressure of the low-pressure forming chamber 4 are fed back by the sensor 6 in real time, and the control cabinet 1 controls the opening and closing of each corresponding part after receiving the feedback signal;

3) After the printing process is completed, stop the vacuum pump 3 through the control panel 2, open the intake valve 5, and open the low-pressure forming chamber 4 after the air completely enters the low-pressure forming chamber 4 and balance the internal and external pressure differences, and take out the printed parts .

The high-performance polymers and their composite materials include pure materials of PA, PC, PE, PPS, PEI, PEKK, PAEK, and PEEK and continuous fibers of carbon fibers, aramid fibers, and glass fibers, as well as the above-mentioned various polymers Chopped fiber pre-impregnated composites and continuous fiber pre-impregnated composites of materials and fibrous materials.

To sum up, the present invention keeps the formed parts at a high temperature for a long time by controlling the three heat dissipation modes of convection heat dissipation, heat conduction heat dissipation, and heat radiation heat dissipation during the forming process of the formed parts, thereby obtaining inter-layer bonding strength, high crystallinity, high High-performance 3D printing parts, in which the low-pressure environment is used to control the convection heat dissipation of the formed parts, supplemented by reducing heat conduction and heat radiation heat dissipation.

The beneficial effects of the present invention are:

Using the low-pressure 3D printing method and device for high-performance polymers and their composite materials of the present invention, the manufacture of high-performance polymer parts can be realized, and the types of formed parts produced are rich in materials. Theoretically, the crystallinity of the formed parts and the combination of high layers The strength will be much higher than the parts printed under normal pressure environment, and the warpage of the printed parts will be small; when the air pressure is low enough, the device can be used for space 3D printing ground simulation verification, highly suitable for space manufacturing, and can be used in space conditions Parts with better performance than those on the ground can be obtained under the ground, breaking through the limitation of space manufacturing.

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the device of the present invention (applicable to pure polymer materials or pre-impregnated composite materials).

Fig. 2 is a schematic diagram of the overall structure of the device of the present invention (applicable to pure polymer materials and dry fibers).

Fig. 3 is a schematic diagram of the porous features of the heating platform of the present invention.

Fig. 4 is a schematic diagram of the principle of the method of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the embodiments and the accompanying drawings.

Referring to FIG. 1 and FIG. 2 , a high-performance polymer and its composite material low-pressure 3D printing device includes a control cabinet 1 and a low-pressure forming chamber 4 , and the control cabinet 1 and the low-pressure forming chamber 4 are electrically connected through a control bus 12 .

The control cabinet 1 includes a control panel 2 and a vacuum pump 3; the control panel 2 includes a low pressure forming chamber air pressure control part, a low pressure forming chamber temperature control part, a print head temperature control part, a heating platform 8 temperature control part and a motion control part , the control bus 12 is connected to the control panel 2 on the upper part of the control cabinet 1 through the aviation plug 11 on the inner wall of the low-pressure forming chamber 4, and the aviation plug 11 can communicate with the electrical part under the condition of ensuring airtightness; the vacuum pump 3 is located under the control cabinet 1 , the vacuum pump 3 is connected to the low-pressure forming chamber 4 through a sealed pipe 13, and air is drawn from the low-pressure forming chamber 4 to provide a low-pressure forming environment.

The low-pressure forming chamber 4 includes an air intake valve 5, a sensor 6, a radiation heating lamp 7, a heating platform 8, and an aviation plug 11; the air intake valve 5 is located outside the low-pressure forming chamber 4 and communicates with the internal and external environments for balancing Internal and external pressure difference; the sensor 6 is located inside the low-pressure forming chamber 4, and is responsible for feeding back the temperature and pressure inside the low-pressure forming chamber 4; the radiation heating lamp tubes 7 are evenly distributed on the inner wall of the low-pressure forming chamber 4, and the heating platform 8 adopts a separate connection method Placed in the low-pressure forming chamber 4, the shock-absorbing pads of the heating platform 8 are used to reduce vibration conduction during the printing process.

Referring to Figure 3, the heating platform 8 has a porous feature and is used with a sandblasting PEI film; the porous feature can ensure that the bubble problem of the PEI film due to the pressure difference is eliminated under a low pressure environment, and the PEI film is a high-performance resin under high temperature conditions. Provide good integration with the printing platform 8.

Referring to Fig. 1 and Fig. 2, in the face of different molding materials, the printing head in the low-pressure molding chamber 4 is divided into two types: one is a single material inlet printing head 9-1, which is made of pure resin filament and short fiber reinforced resin filament One of the continuous fiber-reinforced resin prepregs is used as the raw material to manufacture pure resin and its composite parts. At this time, the corresponding materials used are pure polymer materials \ prepreg materials 10-1, pure polymer Material\Prepreg material 10-1 penetrates from the top of the single material inlet print head 9-1; the other is the dual material inlet in-situ impregnation print head 9-2, which uses continuous fiber filaments and resin filaments as raw materials, It is used to manufacture composite material parts. At this time, the corresponding materials used are fiber material 10-2 and pure polymer material 10-3. The fiber material 10-2 penetrates from the top of the dual-material inlet in-situ dipping print head 9-2. Pure polymer material 10-3 is threaded from the side of the dual material inlet in-situ dipping printhead 9-2.

Both printheads are connected with a typical XYZ type motion mechanism and are provided with motion; the stepper motor, ball screw and limit switch in a typical XYZ type motion mechanism should use vacuum stepper motors, vacuum lead screws and vacuum Fiber switches and other parts suitable for low-voltage environments.

1) High-performance polymers and their composite materials include pure materials of PA, PC, PE, PPS, PEI, PEKK, PAEK, PEEK and continuous fibers of carbon fiber, aramid fiber, and glass fiber, as well as the above-mentioned various polymer materials Chopped fiber pre-impregnated composite material and continuous fiber pre-impregnated composite material with fiber material; After selecting the forming material, close the low-pressure forming chamber 4, close the intake valve 5, and set the target pressure value of the low-pressure forming chamber 4 through the control panel 2 Finally, the vacuum pump 3 extracts the air in the low-pressure forming chamber 4 through the sealed hose 13 to provide a low-pressure environment for the low-pressure forming chamber 4; when the target pressure value is low enough, the low-pressure forming chamber 4 is in a vacuum environment; the existing printing method is in During the part forming process, convection heat dissipation is the main heat dissipation method for the middle and high parts of the formed part, but the low pressure or vacuum environment can greatly reduce the convection heat dissipation between the part and the surrounding environment during the forming process or even completely isolate the convection heat dissipation method, which will make During the forming process, the parts can keep the high temperature state of the material after extrusion for a longer time, which is conducive to sufficient interlayer bonding and crystallization;

2) Use the control panel 2 to set the required low-pressure forming chamber temperature, print head temperature, and heating platform 8 temperature, and select the required motion code to control the typical XYZ-type motion mechanism to move, and complete 3D in the low-pressure forming chamber 4 Printing and forming process; during the printing process, the temperature and pressure of the low-pressure forming chamber 4 are fed back by the sensor 6 in real time, and the control cabinet 1 controls the opening and closing of each corresponding part after receiving the feedback signal; After the head is extruded, it is piled up on the heating platform 8; referring to Figure 4, the low-pressure environment greatly reduces the heat convection and heat dissipation of the formed parts. In the case of only relying on heat radiation for heat dissipation, the extruded material maintains a high temperature state for a long time. The state is conducive to reducing the temperature gradient between the layers of the parts, and the formed parts will obtain higher crystallinity and interlayer bonding strength; during this period, the heating platform 8 can provide heating for the bottom plate, reducing the heat conduction and heat dissipation of the formed parts to the printing platform 8, The ambient heating function of the radiation heating lamp tube 7 further reduces the heat lost by the formed parts to the surrounding radiation heat dissipation;

Claims

A low-pressure 3D printing device for high-performance polymers and their composite materials, characterized in that it includes a control cabinet (1) and a low-pressure forming chamber (4), and the control cabinet (1) and the low-pressure forming chamber (4) are connected through a control bus (12) Electrical connection;

The control cabinet (1) includes a control panel (2) and a vacuum pump (3); the control panel (2) includes a low-pressure forming chamber air pressure control part, a low-pressure forming chamber temperature control part, a print head temperature control part, and a heating platform (8) The temperature control part and the motion control part, the control bus (12) is connected with the control panel (2) on the top of the control cabinet (1) through the aviation plug (11) on the inner wall of the low pressure forming chamber (4); the vacuum pump ( 3) Located under the control cabinet (1), the vacuum pump (3) is connected to the low-pressure forming chamber (4) through a sealed pipe (13) to extract air from the low-pressure forming chamber (4) to provide a low-pressure forming environment.
A high-performance polymer and its composite material low-pressure 3D printing device according to claim 1, characterized in that: the low-pressure forming chamber (4) includes an inlet valve (5), a sensor (6), a radiation The heating lamp (7), the heating platform (8) and the aviation plug (11); the intake valve (5) is located outside the low-pressure forming chamber (4), connected to the internal and external environment, and used to balance the internal and external pressure difference; the sensor (6) Located inside the low-pressure forming chamber (4), it is responsible for feeding back the temperature and pressure inside the low-pressure forming chamber (4); the radiation heating lamps (7) are evenly distributed on the inner wall of the low-pressure forming chamber (4), and the heating platform (8) adopts The separated connection mode is placed in the low-pressure forming chamber (4).
A high-performance polymer and its composite material low-pressure 3D printing device according to claim 2, characterized in that: the bottom of the heating platform (8) is provided with a shock-absorbing foot pad, and the shock-absorbing foot pad is passed through during the printing process. Reduce vibration transmission.
A low-pressure 3D printing device for high-performance polymers and their composite materials according to claim 2, characterized in that: the heating platform (8) has a porous feature and is used with a sandblasting PEI film.
A high-performance polymer and its composite material low-pressure 3D printing device according to claim 1, characterized in that: the printing head in the low-pressure forming chamber (4) is divided into two types: one is a single material The inlet print head (9-1) uses one of pure resin filament, short fiber reinforced resin filament or continuous fiber reinforced resin prepreg filament as raw material to manufacture pure resin and its composite material parts. The material used is a pure polymer material\prepreg material (10-1), and the pure polymer material\prepreg material (10-1) penetrates from the top of the single material inlet print head (9-1); another It is a dual-material inlet in-situ dipping print head (9-2), which uses continuous fiber filaments and resin filaments as raw materials to manufacture composite material parts. At this time, the corresponding materials used are fiber materials (10-2) and pure Polymer material (10-3), fiber material (10-2) penetrates from above the dual material inlet in-situ dipping print head (9-2), pure polymer material (10-3) in-situ from the dual material inlet Side penetration of the dip print head (9-2).
A low-pressure 3D printing device for high-performance polymers and their composite materials according to claim 5, characterized in that: both print heads are connected to a typical XYZ-type motion mechanism and provided with movement; a typical XYZ-type motion mechanism The parts of the stepper motor, ball screw and limit switch should adopt the parts of the vacuum stepper motor, the vacuum screw and the vacuum fiber switch that are suitable for the low-voltage environment.
A high-performance polymer and its composite material low-pressure 3D printing device according to claim 1, characterized in that: the high-performance polymer and its composite material low-pressure 3D printing device is used for producing high-crystallinity, high-layer Polymers and their composite parts with high bonding strength can also be used as a ground verification experimental platform for additive manufacturing in space environments.
The method of utilizing a high-performance polymer and its composite material low-pressure 3D printing device described in claim 2, is characterized in that, comprising the steps of:

1) After setting the target pressure value of the low-pressure forming chamber (4) through the control panel (2), the vacuum pump (3) extracts the air in the low-pressure forming chamber (4) through the sealed hose (13) to form the low-pressure forming chamber (4) ) provides a low-pressure environment; when the target pressure value is low enough, the low-pressure forming chamber (4) is in a vacuum environment;

2) Use the control panel (2) to set the required low-pressure forming chamber temperature, print head temperature, and heating platform (8) temperature, and select the required motion code to control the typical XYZ-type motion mechanism to move. In the low-pressure forming chamber (4) to complete the 3D printing forming process; during the printing process, the temperature and pressure of the low-pressure forming chamber (4) are fed back in real time by the sensor (6), and the control cabinet (1) controls the operation of each corresponding part after receiving the feedback signal turn on and off;

3) After the printing process is completed, stop the vacuum pump (3) through the control panel (2), open the intake valve (5), and open the low-pressure forming chamber after the air completely enters the low-pressure forming chamber (4) and balances the internal and external pressure difference Chamber (4), take out the printed parts.
The method according to claim 8, characterized in that: the high-performance polymer and its composite material include PA, PC, PE, PPS, PEI, PEKK, PAEK, PEEK pure material and carbon fiber, aramid fiber, Continuous fibers of glass fibers also include chopped fiber pre-impregnated composite materials and continuous fiber pre-impregnated composite materials of the above-mentioned various polymer materials and fiber materials.