阅读说明：本技术 传感弹性泡沫及其多通道同轴挤出的增材制造设备与方法 (Additive manufacturing equipment and method for sensing elastic foam and multi-channel coaxial extrusion of sensing elastic foam ) 是由 刘禹 徐嘉文 张星浩 张阳 姜晶 于 2020-12-16 设计创作，主要内容包括：本发明涉及柔性电子技术及增材制造领域,尤其是涉及一种传感弹性泡沫及其多通道同轴挤出的增材制造设备与方法。本发明的传感弹性泡沫为弹性介电单元,由不少于3层的多孔网格堆叠形成,每层多孔网格由核-壳线条结构单元交织形成,所述核-壳线条结构单元包括弹性线条单元、传感单元和导线单元,其中所述传感单元和导线单元为核,弹性线条单元为壳。本发明采用多通道同轴挤出的增材制造设备制备传感弹性泡沫,通过在线调节打印参数达到切换打印不同线条模式的目的,从而完成传感弹性泡沫各个不同功能单元的连续制造。(The invention relates to the field of flexible electronic technology and additive manufacturing, in particular to additive manufacturing equipment and method for sensing elastic foam and multi-channel coaxial extrusion of the elastic foam. The sensing elastic foam is an elastic dielectric unit and is formed by stacking not less than 3 layers of porous grids, each layer of porous grids is formed by interweaving core-shell line structure units, each core-shell line structure unit comprises an elastic line unit, a sensing unit and a lead unit, the sensing unit and the lead unit are cores, and the elastic line unit is a shell. The invention adopts multi-channel coaxial extrusion additive manufacturing equipment to prepare the sensing elastic foam, and achieves the purpose of switching and printing different line modes by adjusting printing parameters on line, thereby completing the continuous manufacturing of different functional units of the sensing elastic foam.)

1. A sensing elastic foam, characterized in that the sensing elastic foam (10) is an elastic dielectric unit formed by stacking not less than 3 layers of porous grids, each layer of porous grids is formed by interweaving core-shell line structure units, the core-shell line structure units comprise elastic line units (101), sensing units (102) and lead units (103), wherein the sensing units (102) and the lead units (103) are cores, and the elastic line units (101) are shells.

2. The sensing elastic foam as claimed in claim 1, wherein the line width of the elastic line unit (101) is 500-2000 μm, and the wall thickness is 100-2000 μm; the line width of the sensing unit (102) is 10-1500 micrometers, and the line width of the conducting wire unit (103) is 10-1500 micrometers.

3. The sensory resilient foam of claim 1, wherein the pattern type of the porous mesh is one of a criss-cross type, a triangular shape, or a hexagonal shape.

4. A multi-channel coaxial extrusion additive manufacturing device is characterized by comprising an air compressor (1), an air path branch head (2), an electronic air pressure valve (3), a connecting air pipe (4), a loading material cylinder (5), a multi-channel coaxial nozzle (6), an XYZ motion module (7), a clamp (8) and a machine body (9), an XYZ motion module (7) is arranged on the machine body (9), the loading material cylinder (5) is fixed on the machine body (9) through a clamp (8), the air compressor (1) is connected with the loading material cylinder (5) and the multi-channel coaxial nozzle (6) through an air path branching head (2) and a connecting air pipe (4), an electronic air pressure valve (3) is arranged between the air path branch head (2) and the loading charging barrel (5), the multi-channel coaxial nozzle (6) is positioned right above the Y-shaped moving module (72).

5. Multi-channel co-axial extrusion additive manufacturing device according to claim 4, wherein the multi-channel co-axial nozzle head (6) comprises a first channel (61), a second channel (62) and a third channel (63), the three channels are inside the co-axial nozzle head, are not communicated with each other and converge at the nozzle head end with a height difference, wherein the third channel (3) envelops the second channel (2), the second channel (2) envelops the first channel (1), and the nozzle head has an overall dimension of 0.6-1.5 mm.

6. A multi-channel co-axial extruded additive manufacturing apparatus according to claim 5, wherein the loading cartridge (5) comprises a sensing material cartridge (51), a wire material cartridge (52) and an elastic material cartridge (53), wherein the sensing material cartridge (51) is connected with the first channel (61) and the sensing material is extruded from the first channel (61);

the wire material barrel (52) is connected with the second channel (62), and the wire material is extruded from the second channel (62);

the elastomeric cartridge (53) is connected to the third passageway (63) and elastomeric material is extruded from the third passageway (3).

7. The multi-channel co-axial extrusion additive manufacturing apparatus of claim 6, wherein the sensing material comprises one or more of a carbon-based conductive liquid, a carbon-based conductive paste, a conductive polymer hydrogel, and a conductive ionic gel, and the sensing material has a conductivity of 10²~10⁵ S/m, viscosity of 10²~10⁶ cps；

The wire material comprises one or more of conductive ionic liquid, conductive polymer solution and gallium indium tin alloy, and has a conductivity of 10⁵~10⁷ S/m, viscosity of 1 to 10³ cps；

The elastic material comprises one or more of polydimethylsiloxane, polyurethane, thermoplastic rubber and thermoplastic resin, and has viscosity of 10⁵~10⁹ cps。

8. The method for line mode conversion and adjustment of the multi-channel coaxial extrusion additive manufacturing equipment according to claim 4, wherein the line mode conversion and adjustment method is mainly used for realizing extrusion of lines in several different modes by switching on and off of air pressure switches of respective channels:

opening a third channel (63), opening a first channel (61), closing a second channel (62), and extruding to form a sensing unit;

opening a third channel (63), closing the first channel (61), opening a second channel (62), and extruding to form a lead unit;

thirdly, opening the third channel (63), closing the first channel (61), closing the second channel (62), and extruding to form an elastic line unit;

the air pressure range of each channel is 0-800 KPa, and the proportion of the line width occupied by the sensing material is adjusted by changing the air pressure proportion of each channel.

9. A method of making a sensory resilient foam according to claim 1, comprising the steps of:

a. installing a multi-channel coaxial nozzle (6) on a clamp at the tail end of a Z-shaped moving module (73);

b. elastic materials, lead materials and sensing materials are correspondingly loaded in the loading material cylinder (5), and are connected with the electronic pneumatic valve (3) and the air compressor (1) through the connecting air pipe (4) and the branch line head (2);

c. generating a printing path through a control system, setting the printing speed of continuous additive manufacturing equipment to be 0.1-50 mm/s, setting extrusion parameters of three line modes,

elastic unit: setting the air pressure of the first channel (61) to be 0 kPa, the air pressure of the second channel (62) to be 0 kPa, and the air pressure of the third channel (63) to be 600-800 kPa;

the sensing unit: setting the air pressure of the first channel (61) to be 0 kPa, the air pressure of the second channel (62) to be 350-400 kPa, and the air pressure of the third channel (63) to be 600-800 kPa;

wire unit: setting the air pressure of the first channel (61) to be 300-500 kPa, the air pressure of the second channel (62) to be 0 kPa, and the air pressure of the third channel (63) to be 600-800 kPa;

d. adjusting the multi-channel coaxial nozzle (6) to a position 0.1-0.9 mm above the plane where the Y-motion module (72) is located, wherein the adjustment height is 0.9 times of the inner diameter of the multi-channel coaxial nozzle (6);

e. the X-axis module and the Y-axis module simultaneously perform path interpolation, control the electronic air pressure valves of all channels to reach required proportion, complete the setting of a printing path and an extrusion line mode, complete self-supporting by utilizing the characteristic of high storage modulus of shell layer elastic materials, and simultaneously extrude lead materials or/and sensing materials from the interior; after the printing of a single layer is finished, lifting the Z-axis module to print the next layer;

f. after the grid structure is printed out, the grid structure is placed in a high-temperature environment with the temperature higher than 80 ℃ to be completely cured, nodes are connected when the grid structure is not cured, good cross-linking can be formed after curing, and internal materials are constrained in the inner layer of the wire body to form a coaxial elastic wire body structure, so that an elastic foam grid is constructed;

g. and f, inserting an external copper wire on the elastic foam grid obtained in the step f to be in contact with a wire material to serve as a lead-out wire, and packaging and forming by using photocuring silica gel to obtain the elastic capacitance sensing grid structure.

10. The method for preparing the sensory elastic foam according to claim 9, wherein auxiliary curing equipment comprising a heat curing heating plate and a heating light source is selectively configured for curing conditions of different materials.

Technical Field

The invention relates to the field of flexible electronic technology and additive manufacturing, in particular to additive manufacturing equipment and method for sensing elastic foam and multi-channel coaxial extrusion of the elastic foam.

Background

With the continuous progress of scientific technology, more and more electronic products are turned to flexibility and personalized customization, such as wearable devices, flexible circuit antennas, microwave cables, electronic skins and the like, and these electronic products not only require the normal operation of electronic components, but also require that the electronic components can be elastically deformed according to the needs of users, and thus flexible sensors therein are required, and have both sensing function and elastic deformation, and such needs undoubtedly create great challenges for the traditional manufacturing. The related research and manufacture of the existing flexible sensor is to embed a conductive material into an elastic material by means of a mold and perform encapsulation molding. However, the related research and manufacture of the existing flexible sensor has the following limitations: (1) the existing flexible sensor is manufactured by adopting a traditional casting mould mode, a mould needs to be manufactured in advance, the production cost is very high, and if different process adjustment is carried out according to different requirements, the mould needs to be replaced according to the requirements, so that a great deal of waste of manpower, time and cost is caused; (2) due to the factors, the existing flexible sensor is difficult to meet more and more personalized customization requirements of users.

Disclosure of Invention

In view of the above problems in the prior art, the present invention provides an additive manufacturing apparatus and method for sensing elastic foam and multi-channel coaxial extrusion thereof. The multi-channel coaxial extrusion additive manufacturing equipment and method for the sensing elastic foam overcome the problems of the traditional mask and layered manufacturing mode, have the advantages of high forming speed, wide applicable materials, uninterrupted process, high customization degree and the like, and integrally save labor, time and production cost.

In order to solve the defects of the prior art, the invention adopts the following technical scheme: the sensing elastic foam is an elastic dielectric unit and is formed by stacking at least 3 layers of porous grids, each layer of porous grids is formed by interweaving core-shell line structure units, each core-shell line structure unit comprises an elastic line unit, a sensing unit and a lead unit, the sensing unit and the lead unit are cores, and the elastic line unit is a shell.

Further, the line width of the elastic line unit is 500-; the line width of the sensing unit is 10-1500 microns, and the line width of the wire unit is 10-1500 microns.

Further, the pattern type of the porous grid is one of a criss-cross type, a triangular shape or a hexagonal shape.

The utility model provides a vibration material disk equipment that multichannel was coaxially extruded, includes air compressor machine, gas circuit branch line head, electron pneumatic valve, connects the trachea, loads feed cylinder, the coaxial shower nozzle of multichannel, XYZ motion module, anchor clamps and fuselage, be provided with XYZ motion module on the fuselage, load the feed cylinder and pass through anchor clamps and fix on the fuselage, the air compressor machine passes through gas circuit branch line head and connects the trachea and load feed cylinder and multichannel coaxial shower nozzle is connected, be provided with electron pneumatic valve between gas circuit branch line head and the loading feed cylinder for the extrusion of different mode lines of control, the coaxial shower nozzle of multichannel is located Y motion module directly over.

Furthermore, the multi-channel coaxial nozzle comprises a first channel, a second channel and a third channel, the three channels are arranged in the coaxial nozzle, are not communicated with each other and converge at the tail end of the nozzle to form a height difference, the third channel envelopes the second channel, the second channel envelopes the first channel, and the overall size of the nozzle is 0.6-1.5 mm.

Further, the loading barrel comprises a sensing material barrel, a wire material barrel and an elastic material barrel, wherein the sensing material barrel is connected with the first channel, and sensing material is extruded from the first channel;

the wire material barrel is connected with the second channel, and the wire material is extruded from the second channel;

the elastomeric cartridge is connected to the third passageway and elastomeric material is extruded from the third passageway.

Further, the sensing material comprises carbon-based conductive liquid, carbon-based conductive paste, conductive polymer hydrogel and conductive ion gelOne or more of the glues, the sensing material having a conductivity of 10²~10⁵ S/m, viscosity of 10²~10⁶ cps；

The wire material comprises one or more of conductive ionic liquid, conductive polymer solution and gallium indium tin alloy, and has a conductivity of 10⁵~10⁷ S/m, viscosity of 1 to 10³ cps；

The elastic material comprises one or more of polydimethylsiloxane, polyurethane, thermoplastic rubber and thermoplastic resin, and has a suitable viscosity of 10⁵~10⁹ cps。

Further, the multi-channel coaxial extrusion additive manufacturing equipment performs line mode conversion and adjustment methods, and the line mode conversion and adjustment methods mainly realize extrusion of lines in different modes by switching on and off of air pressure switches of respective channels:

opening a third channel, opening a first channel, closing a second channel, and extruding to form a sensing unit;

opening a third channel, closing the first channel, opening the second channel, and extruding to form a lead unit;

opening a third channel, closing the first channel and closing the second channel, and extruding to form an elastic line unit;

the air pressure range of each channel is 0-800 KPa, and the proportion of the line width occupied by the sensing material is adjusted by changing the air pressure proportion of each channel.

The preparation method of the sensing elastic foam comprises the following steps:

a. installing the multi-channel coaxial nozzle on a clamp at the tail end of the Z-shaped moving module;

b. elastic materials, lead materials and sensing materials are correspondingly loaded in the loading charging barrel and are connected with the electronic pneumatic valve and the air compressor through the connecting air pipe and the branch line head;

c. generating a printing path through a control system, setting the printing speed of continuous additive manufacturing equipment to be 0.1-50 mm/s, setting extrusion parameters of three line modes,

elastic unit: setting the air pressure of the first channel to be 0 kPa, the air pressure of the second channel to be 0 kPa, and the air pressure of the third channel to be 600-800 kPa;

the sensing unit: setting the air pressure of the first channel to be 0 kPa, the air pressure of the second channel to be 350-400 kPa and the air pressure of the third channel to be 600-800 kPa;

wire unit: setting the air pressure of the first channel to be 300-500 kPa, the air pressure of the second channel to be 0 kPa and the air pressure of the third channel to be 600-900 kPa;

d. adjusting the multi-channel coaxial nozzle to a position 0.1-0.9 mm above the plane where the Y-shaped movement module is located, wherein the adjustment height is 0.9 times of the inner diameter of the multi-channel coaxial nozzle;

e. the motion control technology and the extrusion system control work cooperatively, a printing path and a corresponding line mode are set, self-supporting is completed by utilizing the characteristic of high storage modulus of a shell layer elastic material, and meanwhile, a lead material or/and a sensing material are/is extruded inside;

f. after the grid structure is printed out, the grid structure is placed in a high-temperature environment with the temperature higher than 80 ℃ to be completely cured, nodes are connected when the grid structure is not cured, good cross-linking can be formed after curing, and internal materials are constrained in the inner layer of the wire body to form a coaxial elastic wire body structure, so that an elastic foam grid is constructed;

g. and f, inserting an external copper wire on the elastic foam grid obtained in the step f to be in contact with a wire material to serve as a lead-out wire, and packaging and forming by using photocuring silica gel to obtain the elastic capacitance sensing grid structure.

Further, an auxiliary curing apparatus including a heat curing heating plate and a heating light source is selectively configured for curing cases of different materials.

Compared with the prior art, the invention has the following advantages:

the invention avoids the traditional complex production process of utilizing a die or manually, can meet the requirements of different users on any plane topological structure, geometric dimension and the like, simultaneously has the advantages of good forming, high continuity, uninterrupted process and the like, and saves labor, time and production cost.

The invention adopts liquid or colloid material, and the foam produced by the liquid or colloid material has elasticity due to the good elastic deformation of the liquid or the colloid. When the elastic material is silicon rubber, the prepared elastic foam has obvious advantages because the silicon rubber has good insulativity and elastic deformation capability, is nontoxic and tasteless, resists high temperature and low temperature, and has good inertia.

The invention can continuously switch and print lines with different functional modes, so that the elastic foam structure with the force sensing function can be formed by one-time continuous printing, has the advantages of high integration, high forming speed and the like, and can solve the problem that the sensing unit is led out from a lead inside the elastic foam body.

The method can realize arbitrariness and adjustability through software programming according to requirements; and regulating and controlling printing parameters, namely the distance between the coaxial spray head and the printing substrate, the specification of the coaxial spray head, a preset path and the extrusion air pressure of the extrusion system, so as to realize the adjustment of the wire material and the content of the sensing material in the coaxial lines in the elastic foam, the thickness of the line elastic material and the switching of the line mode.

The multi-channel coaxial nozzle can finish the deposition of lines in different modes in the process of one-time printing, compared with the mode of multi-nozzle switching, the multi-material deposition is finished, the steps of nozzle switching and positioning for head-to-tail printing are omitted, the continuously printed lines have the advantages of being higher in interface performance and higher in printing speed, materials without self-supporting can be used in the inner core materials, and the usable material system is expanded.

Drawings

FIG. 1 is a schematic view showing the structure of a sensor elastic foam in embodiment 1 of the present invention.

FIG. 2 is a schematic structural view of a single coaxial line element in the sensor resilient foam of FIG. 1.

Fig. 3 is a schematic structural diagram of a multi-channel additive manufacturing apparatus of the present invention.

Fig. 4 is a schematic structural view of the multi-channel coaxial showerhead of the present invention.

Fig. 5 is a schematic diagram of a path planning process of sensing elastic foam printing in embodiment 1 of the present invention.

Fig. 6 is a schematic diagram of a path planning process of sensing elastic foam printing in embodiment 2 of the present invention.

Description of reference numerals: 1-an air compressor; 2-gas path branching head; 3-an electronic pneumatic valve; 4-connecting the air pipe; 5-loading the material cylinder; 6-multi-channel coaxial nozzles; 7-XYZ motion module; 8-a clamp; 9-a fuselage; 10-sensing a resilient foam; 101-elastic line unit; 102-a sensing unit; 103-wire unit; 51-a sensing material cartridge; 52-a wire barrel; 53-a cylinder of elastomeric material; 61-a first channel; 62-a second channel; 63-a third channel; 71-X motion module; a 72-Y motion module; 73-Z motion module.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings and examples. It should be understood that the scope of the above-described subject matter is not limited to the following examples, and any techniques implemented based on the disclosure of the present invention are within the scope of the present invention.

Example 1

As shown in fig. 1 and 2, a sensing elastic foam, where the sensing elastic foam 10 is an elastic dielectric unit formed by stacking at least 3 layers of porous grids, each layer of porous grids is formed by interweaving core-shell line structure units, each core-shell line structure unit includes an elastic line unit 101, a sensing unit 102, and a wire unit 103, where the sensing unit 102 and the wire unit 103 are cores, the elastic line unit 101 is a shell, the sensing unit 102 has a resistance, a capacitance, or an inductance that changes significantly after being deformed by a force, heated, or stimulated by other external factors, and the resistance and the change of the wire unit 103 are smaller than those of the sensing unit 102, so that the elastic foam can implement a sensing function.

The line width of the elastic line unit 101 is 1100 microns, and the wall thickness is 1100 microns; the line width of the sensing unit 102 is 1100 microns, the wall thickness is 300 microns, the inner core diameter is 500 microns, the line width of the wire unit 103 is 1100 microns, the wall thickness is 400 microns, and the inner core diameter is 300 microns.

As shown in fig. 3, a material increase manufacturing equipment that multichannel was coaxially extruded, including air compressor machine 1, gas circuit branch line head 2, electron pneumatic valve 3, connecting gas pipe 4, loading feed cylinder 5, multichannel coaxial shower nozzle 6, XYZ motion module 7, anchor clamps 8 and fuselage 9, be provided with XYZ motion module 7 on the fuselage 9, loading feed cylinder 5 passes through anchor clamps 8 to be fixed on fuselage 9, and air compressor machine 1 is connected with loading feed cylinder 5 and multichannel coaxial shower nozzle 6 through gas circuit branch line head 2 and connecting gas pipe 4, be provided with electron pneumatic valve 3 between gas circuit branch line head 2 and the loading feed cylinder 5 for control the extrusion of different mode lines, multichannel coaxial shower nozzle 6 is located Y motion module 71 directly over.

As shown in fig. 4, the multi-channel coaxial nozzle 6 includes a first channel 61, a second channel 62 and a third channel 63, the three channels are in the coaxial nozzle, are not communicated with each other, and converge at the nozzle end to form a height difference, wherein the third channel 3 envelopes the second channel 2, the second channel 2 envelopes the first channel 1, and the nozzle end size is 1.1 mm.

The loading barrel 5 comprises a sensing material barrel 51, a lead material barrel 52 and an elastic material barrel 53, wherein the sensing material barrel 51 is connected with a first channel 61, and sensing material is extruded from the first channel 61;

the wire material barrel 52 is connected with the second channel 62, and the wire material is extruded from the second channel 62;

the elastic material cylinder 53 is connected to the third passage 63, and the elastic material is extruded from the third passage 3.

The sensing material is conductive carbon paste with the conductivity of 4 x 10⁴ S/m, viscosity of 10⁶ cps；

The conducting wire material is a conducting polymer solution with the conductivity of 10⁵ S/m, viscosity of 10³ cps；

The elastic material is polydimethylsiloxane with the viscosity of 5 x 10⁶ cps。

The preparation method of the sensing elastic foam is characterized in that three pressure sensing line units at different positions are embedded in the middle layer, and comprises the following steps:

a. conductive carbon paste is filled in a sensing material cylinder 51 connected with a first channel 61, a conductive polymer solution is filled in a lead material cylinder 52 connected with a second channel 62, and polydimethylsiloxane silicone rubber is filled in an elastic material cylinder 53 connected with a third channel 63;

b. the loading material cylinder 5 and the branch line head 2 are connected with the electronic pneumatic valve 3 and the air compressor 1 through the connecting air pipe 4; the inner diameter and the outer diameter of the tail end of each channel of the spray head are different, wherein the inner diameter of the tail end of the first channel 61 is 0.21 mm, and the outer diameter is 0.4 mm; the inner diameter of the end of the second channel 62 is 0.3 mm, and the outer diameter is 0.45 mm; the inner diameter of the end of the third channel 63 is 0.5 mm, and the outer diameter is 0.6 mm; the three spray heads are arranged in a wedge shape.

c. Generating a printing path through a control system, setting the printing speed of the continuous additive manufacturing equipment to be 15 mm/s, and setting extrusion parameters of three line modes:

elastic unit: setting the air pressure of the first channel 61 to be 0 kPa, the air pressure of the second channel 62 to be 0 kPa, and the air pressure of the third channel 63 to be 700 kPa;

the sensing unit: setting the air pressure of the first channel 61 to 0 kPa, the air pressure of the second channel 62 to 375 kPa, and the air pressure of the third channel 63 to 650 kPa;

wire unit: setting the air pressure of the first channel 61 to be 500 kPa, the air pressure of the second channel 62 to be 0 kPa, and the air pressure of the third channel 63 to be 700 kPa;

the multi-channel coaxial nozzle 6 is adjusted to be 0.9 mm above the plane where the Y-shaped movement module 71 is located;

initially, printing is carried out by using the corresponding air pressure of the elastic unit, when the elastic unit is deposited at a position where lines of the pressure sensing unit need to be placed in the middle layer, printing is carried out by using the corresponding air pressure of the sensing unit, after the sensing unit with a specified length is finished, printing is carried out by using the corresponding air pressure of the wire unit, the printing path is shown in fig. 5, and the elastic unit and the wire unit can be stacked layer by layer to form a grid shape;

d. placing the finished sample into an oven, maintaining the temperature of 80 ℃ for curing for 3 hours, and curing and forming the sensory elastic foam obtained in the step c to obtain the sensory elastic foam with the size of 30 x 10 mm, wherein the width of each coaxial line is about 0.7 mm.

e. And d, inserting copper wires with the diameter of 0.1 mm (the length of the copper wires which are immersed into the coaxial lines is 3-5 mm) into the two ends of each coaxial line of the sensing elastic foam obtained in the step d, injecting UV (ultraviolet) light curing glue into the two ends of the coaxial lines, then carrying out light curing, and leading out a test lead.

And (3) selectively configuring auxiliary curing equipment comprising a thermosetting heating plate and a heating light source according to curing conditions of different materials, and heating and curing the cladding material in the printing process to obtain a better cladding effect.

Finally, a sensor elastic foam as shown in FIG. 1 was produced, and the resistance of the sensor material embedded in the elastic foam was measured using a Keysight LCR meter, which was about 1.5 x 10⁶Omega, resistance 6 x 10 after compression of the foam⁸Ω。

Example 2

A sensing elastic foam is characterized in that the sensing elastic foam 10 is an elastic dielectric unit and is formed by stacking at least 3 layers of porous grids, each layer of porous grid is formed by interweaving a core-shell line structure unit, the core-shell line structure unit comprises an elastic line unit 101, a sensing unit 102 and a lead unit 103, the sensing unit 102 and the lead unit 103 are cores, the elastic line unit 101 is a shell, resistance, capacitance or inductance of the sensing unit 102 changes obviously after being deformed by stress, heated or stimulated by other external factors, and resistance and change of the lead unit 103 are smaller than those of the sensing unit 102, so that the sensing function of the elastic foam can be realized.

The line width of the elastic line unit 101 is 1200 micrometers, and the wall thickness is 1200 micrometers; the line width of the sensing unit 102 is 1200 microns, the wall thickness is 300 microns, the inner core diameter is 600 microns, the line width of the wire unit 103 is 1200 microns, the wall thickness is 450 microns, and the inner core diameter is 300 microns.

As shown in fig. 3, a material increase manufacturing equipment that multichannel was coaxially extruded, including air compressor machine 1, gas circuit branch line head 2, electron pneumatic valve 3, connecting gas pipe 4, loading feed cylinder 5, multichannel coaxial shower nozzle 6, XYZ motion module 7, anchor clamps 8 and fuselage 9, be provided with XYZ motion module 7 on the fuselage 9, loading feed cylinder 5 passes through anchor clamps 8 to be fixed on fuselage 9, and air compressor machine 1 is connected with loading feed cylinder 5 and multichannel coaxial shower nozzle 6 through gas circuit branch line head 2 and connecting gas pipe 4, be provided with electron pneumatic valve 3 between gas circuit branch line head 2 and the loading feed cylinder 5 for control the extrusion of different mode lines, multichannel coaxial shower nozzle 6 is located Y motion module 71 directly over.

As shown in fig. 4, the multi-channel coaxial nozzle 6 includes a first channel 61, a second channel 62 and a third channel 63, the three channels are in the coaxial nozzle, are not communicated with each other, and converge at the end of the nozzle to form a height difference, wherein the third channel 3 envelopes the second channel 2, the second channel 2 envelopes the first channel 1, and the overall size of the nozzle is 1.1 mm.

The loading barrel 5 comprises a sensing material barrel 51, a lead material barrel 52 and an elastic material barrel 53, wherein the sensing material barrel 51 is connected with a first channel 61, and sensing material is extruded from the first channel 61;

the wire material barrel 52 is connected with the second channel 62, and the wire material is extruded from the second channel 62;

the elastic material cylinder 53 is connected to the third passage 63, and the elastic material is extruded from the third passage 3.

The sensing material comprises graphene silica gel with the conductivity of 2 x 10³ S/m, viscosity 4 x 10⁵ cps；

The wire material comprises ionic conductive liquid with the conductivity of 3.3 x 10⁴ S/m, viscosity of 10³ cps；

The elastic material is thermosetting polyurethane with the viscosity of 2 x 10⁸ cps。

The preparation method of the sensing elastic foam is characterized in that three temperature sensing line units at different positions are embedded in the middle layer, and comprises the following steps:

a. a temperature sensing material graphene silica gel is filled in a sensing material cylinder 51 connected with the first channel 61, liquid gallium indium tin alloy is filled in a lead material cylinder 52 connected with the second channel 62, and polyurethane is filled in an elastic material cylinder 53 connected with the third channel 63;

b. the loading material cylinder 5 and the branch line head 2 are connected with the electronic pneumatic valve 3 and the air compressor 1 through the connecting air pipe 4; the inner diameter and the outer diameter of the tail end of each channel of the spray head are different, wherein the inner diameter of the tail end of the first channel 61 is 0.4 mm, and the outer diameter is 0.6 mm; the inner diameter of the tail end of the second channel 62 is 0.6 mm, and the outer diameter is 0.7 mm; the inner diameter of the tail end of the third channel 63 is 0.7 mm, and the outer diameter is 1 mm;

c. generating a printing path through a control system, setting the printing speed of the additive manufacturing equipment to be 50 mm/s, and setting extrusion parameters of three line modes:

elastic unit: setting the air pressure of the first channel 61 to be 0 kPa, the air pressure of the second channel 62 to be 0 kPa, and the air pressure of the third channel 63 to be 800 kPa;

the sensing unit: setting the air pressure of the first channel 61 to be 0 kPa, the air pressure of the second channel 62 to be 400 kPa and the air pressure of the third channel 63 to be 800 kPa;

wire unit: setting the air pressure of the first channel 61 to be 500 kPa, the air pressure of the second channel 62 to be 0 kPa and the air pressure of the third channel 63 to be 800 kPa;

the multi-channel coaxial nozzle 6 is adjusted to be 0.45 mm above the plane where the Y-shaped movement module 71 is located, and the adjustment height is 0.9 times of the inner diameter of the multi-channel coaxial nozzle 6;

initially, printing is carried out by using the corresponding air pressure of the elastic unit, when the elastic unit is deposited at a position where a temperature sensing unit line needs to be placed in the middle layer, printing is carried out by using the corresponding air pressure of the sensing unit, after the sensing unit with a specified length is finished, printing is carried out by using the corresponding air pressure of the wire unit, the printing path is as shown in fig. 6, and the elastic unit and the wire unit can be stacked layer by layer to form a grid shape;

d. and (c) placing the finished sample into an oven, keeping the temperature of 80 ℃ for curing for 3 hours, and curing and forming the sensing elastic foam obtained in the step c to obtain the elastic foam with temperature sensing, wherein the width of each coaxial line is about 1.2 mm.

e. And d, inserting copper wires with the diameter of 0.1 mm (the length of the copper wires which are immersed into the coaxial lines is 3-5 mm) into the two ends of each coaxial line of the sensing elastic foam obtained in the step d, injecting UV (ultraviolet) light curing glue into the two ends of the coaxial lines, then carrying out light curing, and leading out a test lead.

And (3) selectively configuring auxiliary curing equipment comprising a thermosetting heating plate and a heating light source according to curing conditions of different materials, and heating and curing the cladding material in the printing process to obtain a better cladding effect.

Finally, temperature sensing elastic foam is prepared, an LCR (liquid crystal storage controller) table of Keysight company is utilized to measure the resistance of the graphene silica gel embedded in the elastic foam, and the value of the resistance is about 3 x 10 at the normal temperature of 25 DEG C⁶Omega, resistance of 3.42 x 10 at around 0 ℃ ambient temperature⁶Ω。

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modification, change and equivalent changes of the above embodiments according to the principles of the present invention are still within the protection scope of the technical solution of the present invention.