Bi-material composite printing nozzle
By optimizing the design of the dual-material composite 3D printing nozzle, the use of semiconductor refrigeration sheets to achieve active temperature control between the barrel and needle, solving the problem of insufficient temperature control during material transportation, improving printing quality and efficiency, and is especially suitable for living cell materials.
Patent Information
- Application Number
- CN202422628677.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-30
- Publication Date
- 2025-08-29
- Estimated Expiration
- 2034-10-30
AI Technical Summary
The existing dual-material composite 3D printing nozzles have insufficient temperature control during material transportation, resulting in unstable material performance, especially the reduction of biological activity of active cellular materials, while increasing system complexity and maintenance difficulty.
A dual-material composite printing nozzle is designed, including a first ink cartridge, a second ink cartridge, and a composite printing needle. A semiconductor refrigeration sheet is used to realize active temperature control between the barrel and the needle, shorten the material conveying distance, and through the compact design of the inner and outer needle components, the conveying pressure is reduced and multi-point temperature control is achieved.
Effectively control the material temperature in the range of -5℃ to 40℃, reduce temperature changes during the transportation process, improve printing quality and efficiency, and is especially suitable for living cell materials, simplifying system structure and maintenance processes.
Smart Images
Figure CN223278549U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of 3D printing, and in particular relates to a dual-material composite printing nozzle. Background Art
[0002] With the rapid development of 3D printing technology, dual-material composite printing technology has attracted widespread attention due to its ability to print materials with different physical or chemical properties. However, existing dual-material composite 3D printing nozzle designs have limitations and are generally divided into the following three categories:
[0003] (1) Single nozzle without temperature control: This solution only contains two uncontrollable temperature ink cartridges and needles. The material lacks temperature control during storage and transportation, which may lead to unstable material properties and affect printing quality.
[0004] (2) Three-way material feeding and mixing nozzle: This solution uses two temperature-controlled single-cartridge nozzles and achieves material mixing through a three-way material feeding and mixing needle. Although the nozzle itself has a temperature control function, the material needs to pass through a long delivery tube to reach the needle during the delivery process, and there is a lack of insulation measures or active temperature control methods during the delivery process, resulting in the material's performance being affected by temperature changes during the delivery process.
[0005] (3) Syringe pump and three-way material mixing: This solution is completely implemented by two syringe pumps and a three-way material mixing needle. Although it can achieve precise material delivery, the delivery distance is long during the entire process and the necessary temperature control measures are lacking. This not only increases the complexity of the system, but also increases the pressure of the material during the delivery process, which is not conducive to the preservation of the material and the printing of active cell materials.
[0006] As can be seen from the above, existing nozzle designs present at least the following issues during material delivery: Due to the long delivery distance, the material must overcome significant pressure during transport, which not only increases the system's energy consumption but can also cause changes in the material's physical properties, impacting print quality. There is a lack of effective temperature control during transport, particularly for materials containing active cells. Temperature fluctuations can reduce cell viability, affecting the bioactivity of the print. The syringe pump and three-way mixing system increase system complexity, potentially making maintenance and operation difficult.
[0007] Therefore, the utility model provides a new dual-material composite 3D printing nozzle, which optimizes the nozzle design, reduces the material delivery distance, achieves effective temperature control, and simplifies the system structure to improve the printing quality, especially in the application of printing active cell materials. Utility Model Content
[0008] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a dual-material composite printing nozzle.
[0009] The present invention is implemented as follows: a dual-material composite printing nozzle includes a first ink cartridge, a second ink cartridge, and a composite printing needle; the composite printing needle includes a needle holder, an inner needle assembly, a transmission needle, and a shell needle assembly; the needle of the inner needle assembly extends into the shell needle assembly, and the shell needle assembly is fixed by the needle holder; the feed port of the first ink cartridge is connected to the first ink delivery mechanism, and the discharge port is connected to the feed port of the inner needle assembly; the feed port of the second ink cartridge is connected to the second ink delivery mechanism, and the discharge port is connected to the feed port of the transmission needle.
[0010] Preferably, the first ink cartridge and the second ink cartridge have the same structure, both comprising a barrel and a temperature control assembly; a temperature control assembly is provided on the periphery of the barrel; the temperature control assembly comprises a temperature control barrel, a heat dissipation base plate, a first semiconductor refrigeration plate, and a water tank cover; the temperature control barrel is wrapped around the periphery of the barrel; the cold end of the first semiconductor refrigeration plate is in close contact with the outer wall of the temperature control barrel.
[0011] Preferably, the first ink cartridge and the second ink cartridge are further provided with an adapter located at the feed port, and are connected to the corresponding first ink delivery mechanism and the second ink delivery mechanism via the adapter.
[0012] Preferably, the inner needle assembly includes an inner needle and an inner needle holder; the feed port of the inner needle is connected to the discharge port of the first ink cartridge, and its needle passes through the inner needle holder and extends into the shell needle assembly; the shell needle assembly includes an integrally formed shell needle holder and a shell needle; the needle of the inner needle passes through the shell needle holder and extends into the shell needle; the discharge port of the transmission needle is connected to the internal material conveying passage of the composite printing needle; one end of the internal material conveying passage of the composite printing needle is connected to the outside of the inner needle holder, and the other end serves as a cleaning port; the cleaning port is sealed by a detachably connected seal; the inner needle holder is provided with a plurality of small holes on at least the side in contact with the internal material conveying passage of the composite printing needle, so that the second ink conveyed by the transmission needle enters the inner cavity of the inner needle holder and enters the internal hole of the shell needle assembly through the retaining hole.
[0013] More preferably, the composite printing needle head further includes a second semiconductor refrigeration plate and an adsorption base plate; the adsorption base plate is arranged on the outside of the needle head frame, and the cold end of the second semiconductor refrigeration plate is close to the outer side wall of the adsorption base plate.
[0014] More preferably, the hot end of the first semiconductor refrigeration plate and the hot end of the second semiconductor refrigeration plate are both in close contact with the inner wall of the water tank cover; and the outer wall of the water tank cover is provided with the heat dissipation base plate.
[0015] More preferably, the inner needle holder is provided with a retaining hole, through which the needle of the inner needle passes; the aperture d1 of the retaining hole satisfies d1=d0+a, wherein d0 represents the needle diameter of the inner needle, a represents the gap, and the value of a is designed according to the flow rate of the second ink.
[0016] More preferably, the needle head of the inner needle, the central axis of the retaining hole of the inner needle holder, the central axis of the inner hole of the shell needle holder 15 and the central axis of the inner hole of the shell needle coincide with each other.
[0017] More preferably, the diameter d2 of the inner hole of the shell needle satisfies d2=d0+b, wherein d0 represents the needle diameter of the inner needle, b represents the gap, and the value of b is designed according to the flow rate of the second ink.
[0018] More preferably, the distance d3 that the needle tip of the inner needle extends beyond the inner hole of the shell needle satisfies [0, c], and the value of c is adjusted according to actual needs.
[0019] The beneficial effects of the present invention include at least:
[0020] The 3D printing nozzle of this utility model shortens the conveying distance of the first ink and the second ink from the barrel to the printing nozzle outlet through the unique design of the first ink cartridge and the second ink cartridge. The barrels storing the first ink and the second ink have a heat preservation function, which can achieve active temperature control from -5°C to 40°C. The composite printing needle also has a heat preservation function, which can achieve active temperature control from -5°C to 40°C, realizing multi-point temperature control, minimizing the impact of temperature changes on the material during the conveying process, and is particularly suitable for printing materials containing living cells. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0022] Figure 1 It is a structural diagram of an embodiment provided by the embodiment of the present utility model.
[0023] Figure 2 It is a structural schematic diagram of the first ink cartridge provided by an embodiment of the utility model.
[0024] Figure 3 It is a schematic diagram of the exploded structure of the composite printing needle provided in an embodiment of the present utility model.
[0025] Markings in the figure: 1. Adapter; 2. Barrel; 3. Elastic fixing block; 4. Shell; 5. Temperature control barrel; 6. Inner needle; 7. Inner needle holder; 8. First O-ring; 9. Needle holder; 10. Transmission needle; 11. O-ring pressure block; 12. Second O-ring; 13. Third O-ring; 14. Thumb screw; 15. Shell needle holder; 16. Shell needle; 17. Heat dissipation base plate; 18. First semiconductor refrigeration plate; 19. Second semiconductor refrigeration plate; 20. Sink cover; 21. Adsorption base plate; 22. Fourth O-ring. DETAILED DESCRIPTION
[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.
[0027] like Figure 1-3 As shown, this embodiment provides a dual-material composite 3D printing nozzle designed to address existing dual-material printing issues, improving printing quality and efficiency. It is particularly suitable for printing materials containing living cells. By regulating and controlling the material temperature throughout the printing process, temperature control can be achieved in different areas of the nozzle. Furthermore, dual-material composite printing requires a short path, shortening material transport distances and requiring low drive pressure, facilitating the storage, transfer, and printing of cell-containing materials.
[0028] The utility model specifically includes a first ink cartridge, a second ink cartridge, and a composite printing needle;
[0029] The composite printing needle includes a needle holder 9, an inner needle assembly, a transfer needle 10, and a shell needle assembly; the needle of the inner needle assembly extends into the shell needle assembly, and the shell needle assembly is secured by the needle holder 9. This nozzle facilitates various combinations. The inner needle assembly, which serves as the inner material delivery needle, and the transfer needle 10, which serves as the outer material delivery needle, can be quickly assembled and nested, allowing for tool-free disassembly and cleaning. All disassembly can be broken down into individual parts without tools, allowing for thorough cleaning during post-printing maintenance. High-temperature, high-pressure steam, ultrasound, and other cleaning methods are also available. The next time it is used, simply insert the parts into the assembly in order, without the need for additional tools.
[0030] The feed port of the first ink cartridge is connected to the first ink delivery mechanism, and the discharge port is connected to the feed port of the inner needle assembly; the feed port of the second ink cartridge is connected to the second ink delivery mechanism, and the discharge port is connected to the feed port of the transmission needle 10.
[0031] Specifically, the first ink and the second ink involved in this embodiment can be made of the same material or different materials.
[0032] Specifically, the first and second ink cartridges involved in this embodiment have independent outlets and independent extrusion pressures. The materials extruded from the outlets of the first and second ink cartridges converge at a composite printing needle and are extruded along the needle tip of the composite printing needle. The needle tip can have a variety of cross-sectional patterns, such as concentric, plum blossom, and octagonal star shapes.
[0033] In a preferred embodiment of the present invention, the first ink cartridge and the second ink cartridge have the same structure, both including a barrel 2 and a temperature control assembly; the outer periphery of the barrel 2 is provided with a temperature control assembly; the temperature control assembly includes a temperature control barrel 5, a heat dissipation base plate 17, and a first semiconductor refrigeration plate 18; the temperature control barrel 5 is wrapped around the outer periphery of the barrel 2; the cold end of the first semiconductor refrigeration plate 18 is in close contact with the outer wall of the temperature control barrel 5. The present invention designs the barrel 2 and the composite printing needle into a compact device, and the printing material enters the composite printing needle directly from the barrel 2 without any additional conveying pipe in between. The first ink and the second ink are conveyed from the barrel 2 to the needle outlet of the composite printing needle, with the needle conveying distances of the first ink and the second ink being 25.4 mm and 30 mm, respectively.
[0034] In a preferred embodiment of the present invention, each of the first and second ink cartridges is further provided with an adapter 1 located at the feed port, and is connected to the corresponding first and second ink delivery mechanisms via the adapter 1. With the printer's auxiliary control, the extrusion pressure and extrusion switch of the two ink cartridges of the print head can be independently set.
[0035] The inner needle assembly includes a needle-tube-shaped inner needle 6 with a standard Luer interface and an inner needle holder 7; the feed port of the inner needle 6 is connected to the discharge port of the first ink cartridge, and its needle passes through the inner needle holder 7 and extends into the shell needle assembly.
[0036] Specifically, the inner needle 6 is inserted into the inner needle holder 7, with an appropriate clearance between the inner needle holder 7 and the inner needle 6. There is slight resistance during insertion, but the inner needle holder 7 remains stable after assembly. Specifically, the inner needle holder 7 has a retaining hole through which the inner needle 6 passes. The retaining hole has a diameter d1 that satisfies d1 = d0 + a, where d0 represents the diameter of the inner needle 6 and a represents the clearance. The value of a is designed based on the flow rate of the second ink.
[0037] The shell needle assembly includes an integrally formed shell needle frame 15 and a shell needle 16; the needle tip of the inner needle 6 passes through the shell needle frame 15 and extends into the shell needle 16; the discharge port of the transmission needle 10 is connected to the internal material conveying passage of the composite printing needle; one end of the internal material conveying passage of the composite printing needle is connected to the outside of the inner needle holder 7, and the other end serves as a cleaning port; the cleaning port is sealed by a detachably connected seal; in this embodiment, the hand screw 14 is used as a seal, and a third O-ring 13 is installed at its end. After being screwed into the needle frame 9, the material conveying passage of the needle frame 9 is sealed, and the material does not leak.
[0038] Specifically, the outer diameter of the inner needle holder 7 matches the inner cavity of the outer needle holder 15. The inner needle holder 7's central internal hole and outer diameter are highly concentric, with an error of no more than 0.01 mm. A groove is formed on the outer circumference of the inner needle holder 7, housing a first O-ring 8 that seals the gap between the outer needle holder 15 and the inner needle holder 7.
[0039] The inner needle holder 7 is mounted within the shell needle holder 15, and the outer layer is tightly fitted with the needle holder 9. The shell needle holder 15, the inner needle holder 7, and the needle holder 9 are sealed with a first O-ring 8 and a fourth O-ring 22, respectively. The inner hole of the shell needle holder 15 maintains a high degree of concentricity, with an error of no more than 0.01 mm. The inner needle holder 7 is mounted at the large hole end of the shell needle holder 15, and the shell needle 16 is mounted at the small hole end.
[0040] In a preferred embodiment of the present invention, the inner needle holder 7 is provided with a plurality of small holes at least on the side in contact with the internal material delivery passage of the composite printing needle, so that the second ink delivered by the transmission needle 10 enters the inner cavity of the inner needle holder 7 and enters the internal hole of the shell needle 16 through the retaining hole.
[0041] In a preferred embodiment of the present invention, the transfer needle 10 is a standard Luer-connected, cannulated needle. The Luer-connected end of the inner needle 6 is attached to the discharge port of the barrel 2. The diameter of the cannula is at least 1 mm. The cannula is inserted into an O-ring block 11, which tightly fits within a second O-ring 12. During operation, compressed air from the barrel 2 forces material through the transfer needle 10, into the material delivery path within the needle holder 9, and then into the inner needle holder 7.
[0042] In a preferred embodiment of the present invention, the composite printing needle further comprises a second semiconductor cooling sheet 19 and an adsorption base plate 21. The adsorption base plate 21 is positioned outside the needle holder 9, with the cold end of the second semiconductor cooling sheet 19 adjacent to the outer wall of the adsorption base plate 21. The adsorption base plate 21 is secured to the water tank cover 20 via screws. During operation, the needle holder 9 engages the adsorption base plate 21, transferring heat from the needle holder 9 to the second semiconductor cooling sheet 19.
[0043] In a preferred embodiment of the present invention, the hot ends of the first semiconductor refrigeration plate 18 and the second semiconductor refrigeration plate 19 are both in close contact with the inner wall of the water tank cover 20; the outer wall of the water tank cover 20 is provided with the heat dissipation base plate 17. There is an annular water channel cavity inside the heat dissipation base plate 17, which is welded and sealed with the water tank cover 20. In this embodiment, the temperature control barrel 5 is installed on the water tank cover 20 by screws, thereby pressing the first semiconductor refrigeration plate 18. During operation, the cold end of the first semiconductor refrigeration plate 18 is transferred to the barrel 2 through the temperature control barrel 5, and the hot end of the first semiconductor refrigeration plate 18 dissipates heat through the water tank cover 20. In addition, the temperature control barrel 5 is also equipped with an outer shell 4.
[0044] This embodiment utilizes two semiconductor refrigeration chips—the hot end of a first semiconductor refrigeration chip 18 and a second semiconductor refrigeration chip 19—mounted on a water tank cover 20, ensuring excellent thermal conductivity. Consequently, the barrel 2 containing the first and second inks maintains an active temperature control range of -5°C to 40°C thanks to the insulation provided by the first semiconductor refrigeration chip 18. The entire needle delivery section also maintains an active temperature control range of -5°C to 40°C thanks to the second semiconductor refrigeration chip 19. This effectively minimizes the impact of environmental fluctuations on material delivery. This is particularly true for materials containing living cells, where lower environmental pressure is more beneficial to cell survival.
[0045] In a preferred embodiment of the present invention, the first ink cartridge and the second ink cartridge are each further provided with an elastic fixing block 3 installed at the end of the heat dissipation base plate 17. The elastic portion of the elastic fixing block 3 presses the barrel 2 so that the barrel 2 does not move up and down during operation, and the elastic fixing block 3 can achieve locking and fixation.
[0046] Specifically, the needle tip of the inner needle 6, the central axis of the retaining hole of the inner needle holder 7, the central axis of the inner hole of the shell needle holder 15, and the central axis of the inner hole of the shell needle 16 coincide with each other. In other words, through the concentric design, the inner needle 6 and the inner needle holder 7 remain concentric, the shell needle holder 15 and the inner needle holder 7 remain concentric, the shell needle 16 and the shell needle holder 15 remain concentric, and ultimately the inner needle 6 and the shell needle 16 remain concentric.
[0047] Specifically, the diameter d2 of the inner hole of the shell needle 16 satisfies d2=d0+b, where d0 represents the needle diameter of the inner needle 6, b represents the gap, and the value of b is designed according to the flow rate of the second ink.
[0048] Specifically, the distance d3 that the needle tip of the inner needle 6 extends beyond the inner hole of the shell needle 16 satisfies [0, c], and the value of c is adjusted according to actual needs.
[0049] The needle holder 9 has a material delivery passage inside, which is connected to the adsorption base plate 21 by a concave-convex buckle. When working, the needle holder 9 can transfer heat through the adsorption base plate 21 to reduce the temperature.
[0050] like Figure 3 As shown in the exploded diagram, the shell needle holder 15 is inserted into the internal hole of the needle holder 9, the inner needle holder 7 is inserted into the internal hole of the shell needle holder 15, and the inner needle 6 is inserted into the internal hole of the inner needle holder 7. The transmission needle 10 is inserted into the small hole of the O-ring pressure block 11, sealingly engaging the second O-ring 12 inside the O-ring pressure block 11. The thumb screw 14 can be screwed directly into the needle holder 9 by hand. All of the above components are designed to fit between the holes and the shafts, and can be disassembled by pulling them apart one by one. High-temperature, high-pressure steam or ultrasonic cleaning can be used for cleaning. This utility model has excellent maintenance performance, and no additional tools are required for disassembly, maintenance, or assembly.
[0051] The first ink is delivered to the barrel 2 of the first ink cartridge via the first ink delivery mechanism, where it is pressured into the inner needle 6 and extruded directly from the tip of the inner needle 6. The second ink is delivered to the barrel 2 of the second ink cartridge via the second ink delivery mechanism, where it is pressured into the transfer needle 10, then into the material delivery path. It then passes through the small holes in the sidewall of the inner needle holder 7, into the inner cavity of the inner needle holder 7, and finally is extruded sequentially through the retention holes, the internal holes of the shell needle holder 15, and the internal holes of the shell needle 16. Under the same printing parameters, with a needle diameter of 0.8 mm for the inner needle 6 and a printing speed of 5 mm / s, composite printing can be achieved with an air pressure of 0.2 MPa. Under the same conditions, conventional composite printing requires an air pressure of 0.6 MPa. This demonstrates that the present invention effectively reduces the air pressure required for material delivery, significantly optimizing printing parameters. This is particularly true for biomaterials containing living cells, where lower extrusion pressure is more beneficial for cell survival. Furthermore, the ink cartridge of this embodiment's printhead features a micro-environmental control function, actively regulating the temperature of the ink being printed. The cartridge has multiple independent temperature zones: each dual-material cartridge has an independent temperature control module, and the needle, where the materials converge, has another independent temperature control module, for a total of three temperature control modules. The temperature control modules in the two ink cartridges and the needle are arranged closely together to minimize the impact of temperature fluctuations during material transport, ensuring optimal temperature control during both material storage and mixing during printing.
[0052] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.
Claims
1. A dual-material composite printing nozzle, characterized in that It includes a first ink cartridge, a second ink cartridge, and a composite printing needle; The composite printing needle comprises a needle holder (9), an inner needle assembly, a transmission needle (10), and a shell needle assembly; the needle of the inner needle assembly extends into the shell needle assembly, and the shell needle assembly is fixed by the needle holder (9); The feed port of the first ink cartridge is connected to the first ink delivery mechanism, and the discharge port is connected to the feed port of the inner needle assembly; the feed port of the second ink cartridge is connected to the second ink delivery mechanism, and the discharge port is connected to the feed port of the transmission needle (10).
2. A dual-material composite printing nozzle according to claim 1, characterized in that: The first ink cartridge and the second ink cartridge have the same structure, both comprising a barrel (2) and a temperature control component; a temperature control component is provided on the periphery of the barrel (2); the temperature control component comprises a temperature control barrel (5), a heat dissipation base plate (17), a first semiconductor refrigeration plate (18), and a water tank cover (20); the temperature control barrel (5) is wrapped around the periphery of the barrel (2); the cold end of the first semiconductor refrigeration plate (18) is in close contact with the outer wall of the temperature control barrel (5).
3. A dual-material composite printing nozzle according to claim 1, characterized in that: The first ink cartridge and the second ink cartridge are both provided with an adapter (1) located at the feed port, and are connected to the corresponding first ink delivery mechanism and the second ink delivery mechanism via the adapter (1).
4. A dual-material composite printing nozzle according to claim 1, characterized in that: The inner needle assembly comprises an inner needle (6) and an inner needle holder (7); the feed port of the inner needle (6) is connected to the discharge port of the first ink cartridge, and the needle thereof passes through the inner needle holder (7) and extends into the shell needle assembly; the shell needle assembly comprises an integrally formed shell needle holder (15) and a shell needle (16); the needle of the inner needle (6) passes through the shell needle holder (15) and extends into the shell needle (16); the discharge port of the transmission needle (10) is connected to the inner portion of the composite printing needle. The material delivery passage is connected; one end of the material delivery passage inside the composite printing needle is connected to the outside of the inner needle holder (7), and the other end serves as a cleaning port; the cleaning port is sealed by a detachably connected sealing member; the inner needle holder (7) is provided with a plurality of small holes at least on the side in contact with the material delivery passage inside the composite printing needle, so that the second ink delivered by the transmission needle (10) enters the inner cavity of the inner needle holder (7) and enters the inner hole of the shell needle assembly through the retaining hole.
5. The dual-material composite printing nozzle according to claim 2, characterized in that: The composite printing needle head also includes a second semiconductor cooling plate (19) and an adsorption base plate (21); the adsorption base plate (21) is arranged on the outside of the needle head frame (9), and the cold end of the second semiconductor cooling plate (19) is close to the outer wall of the adsorption base plate (21).
6. A dual-material composite printing nozzle according to claim 5, characterized in that: The hot end of the first semiconductor refrigeration plate (18) and the hot end of the second semiconductor refrigeration plate (19) are both in close contact with the inner wall of the water tank cover (20); the outer wall of the water tank cover (20) is provided with the heat dissipation base plate (17).
7. A dual-material composite printing nozzle according to claim 4, characterized in that: The inner needle holder (7) is provided with a retaining hole, through which the needle of the inner needle (6) passes; the aperture d1 of the retaining hole satisfies d1=d0+a, wherein d0 represents the needle diameter of the inner needle (6), a represents the gap, and the value of a is designed according to the flow rate of the second ink.
8. The dual-material composite printing nozzle according to claim 4, characterized in that: The needle head of the inner needle head (6), the center axis of the retaining hole of the inner needle head holder (7), the center axis of the inner hole of the shell needle head holder (15) and the center axis of the inner hole of the shell needle head (16) coincide with each other.
9. The dual-material composite printing nozzle according to claim 4, characterized in that: The aperture d2 of the inner hole of the shell needle (16) satisfies d2=d0+b, wherein d0 represents the needle diameter of the inner needle (6), b represents the gap, and the value of b is designed according to the flow rate of the second ink.
10. The dual-material composite printing nozzle according to claim 4, characterized in that: The distance d3 that the needle head of the inner needle head (6) extends beyond the inner hole of the shell needle head (16) satisfies [0, c], and the value of c is adjusted according to actual needs.