Using method and device of pressure-bearing iris variable-aperture extrusion nozzle for 3D printing

Abstract

The invention discloses a using method and device of a pressure-bearing type iris variable-aperture extrusion nozzle for 3D printing, and relates to the technical field of additive manufacturing material deposition, the pressure-bearing type iris variable-aperture extrusion nozzle comprises a 3D printing hot end, a detachable pressure-bearing type iris extrusion nozzle assembly, an axial lifting mechanism and a control system, the 3D printing hot end is composed of a pneumatic connector, a heat dissipation pipe, a polytetrafluoroethylene material guide pipe, a throat pipe and a nozzle, the device is composed of a sealing metal elastic sheet, a cooling fan, a fan support, a heating module, a sealing metal elastic sheet, a mounting interface, a detachable pressure-bearing iris extrusion nozzle and an axial lifting mechanism. The pressure-bearing type iris extrusion mechanism is arranged, and a worm and gear speed reduction driving mode is combined, so that the aperture of an extrusion opening is continuously adjustable, the extrusion flow can be accurately adjusted in the printing process according to process requirements, and the flexibility and consistency of printing forming are effectively improved; meanwhile, the embedded column type pressure-bearing iris blade adopts a pressure-bearing structure and is matched with a pressing metal elastic plate and a limiting structure, good sealing performance and structural stability can still be kept under the high-temperature and high-pressure extrusion condition, and the material leakage and blocking risk is reduced. Furthermore, the iris extrusion nozzle is designed to be a detachable module, maintenance and replacement are convenient, accurate adjustment of the position of the nozzle is achieved through an axial lifting mechanism, and the reliability and adaptability of equipment operation are improved. On the whole, the multi-material and multi-working-condition 3D printing extrusion device is simple in structure, reliable in transmission, high in control precision, low in manufacturing and maintenance cost and suitable for multi-material and multi-working-condition 3D printing extrusion application.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing material deposition technology, specifically to a method and apparatus for using a pressure-bearing iris variable aperture extrusion nozzle for 3D printing. Background Technology

[0002] 3D printing, as a typical additive manufacturing technology, constructs three-dimensional solids by stacking layers or voxels one by one, and has become an important supplement to traditional subtractive and additive manufacturing methods. With the continuous development and popularization of 3D printing technology, the design and manufacturing of various printers are increasingly focusing on detail and diversification. In thermoplastic material extrusion 3D printing equipment, the nozzle, as a key component, directly determines core performance aspects such as material flow rate, linewidth, forming accuracy, and printing speed. Traditional 3D printing nozzles extrude according to a fixed orifice size, making real-time adjustments impossible based on material flow, printing speed, and layer thickness requirements. Nozzle replacement requires manual disassembly or multi-nozzle switching mechanisms, making it difficult to balance high-speed printing and high-precision forming, thus hindering the intelligent development of printing. Summary of the Invention

[0003] This invention provides a method and apparatus for using a pressure-bearing iris variable aperture extrusion nozzle for 3D printing. The aim is to achieve adjustable nozzle size during the printing process to balance printing accuracy and efficiency. The apparatus uses a pressure-bearing iris mechanism to change the aperture at any time during the printing process, changes the installation position of the blades and wheel of a conventional iris mechanism, and embeds a sliding column to ensure a flat extrusion surface. It can perform highly automated and precise operations and adapt to nozzle diameter variations within millimeters for small and medium-sized precision printing.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows:

[0005] This invention relates to a method and apparatus for using a pressure-bearing iris variable aperture extrusion nozzle for 3D printing, comprising a 3D printing hot end and a control system. The 3D printing hot end consists of a pneumatic connector, a heat dissipation pipe, a polytetrafluoroethylene feed tube, a throat, a nozzle, a sealing metal spring, a cooling fan, a fan bracket, a heating module, a sealing metal spring, a mounting interface, a detachable pressure-bearing iris extrusion nozzle, and an axial lifting mechanism.

[0006] The detachable pressure-bearing iris extrusion nozzle assembly includes: an iris fixing base plate, an iris driving movable plate, an embedded column-type pressure-bearing iris blade, a metal spring, a clamping metal spring plate, an iris shell, a sector-shaped worm gear section, a worm gear drive shaft, a reduction gear motor, a worm gear protective shell, and a radial limiting sleeve for the iris blade. The axial lifting mechanism includes: a lifting mechanism fixing seat, a lifting mechanism sliding seat, an axial transmission screw, a lifting mechanism protective shell, a transmission mechanism, and external circuitry.

[0007] In the hot end of 3D printing, the pneumatic connector is located at the upper end of the heat dissipation tube, and the two are connected by threads. The inner cavity of the pneumatic connector is connected to the axial through hole of the heat dissipation tube, and is used to axially limit and seal the PTFE guide tube. The PTFE guide tube is located in the inner cavity of the heat dissipation tube, with its upper end pressed and fixed by the pneumatic connector, and its lower end extending into the throat tube, used to guide the printing material downward and isolate heat transfer upward. The throat tube is located at the lower end of the heat dissipation tube and is connected to the nozzle, and the two are connected by threads. The throat tube has a low thermal conductivity structure, and its inner cavity is connected to the lower end of the PTFE guide tube to realize the transition of material from the cold end to the hot end. The nozzle is located at the lower end of the throat tube, and the nozzle and throat tube are fixed by threaded connection. The axial through holes of the two are interconnected, and are used to extrude the molten material into... The nozzle is designed as follows: The heating module is located outside the nozzle and is fixedly connected to it via fasteners or a heating block structure. The heating module heats the nozzle and its internal materials, causing the printing material to melt. The cooling fan is located outside the heat dissipation pipe and is fixedly connected to it via a fan bracket. The fan's exhaust direction is towards the outer surface of the heat dissipation pipe, providing forced air cooling. The sealing metal spring is located at the connection between the throat and the nozzle. When the nozzle is tightened, the sealing metal spring generates an axial elastic preload to compensate for thermal expansion and improve the sealing performance of the connection, preventing leakage of molten material. The clamping metal plate is located at the bottom of the nozzle and applies axial or radial preload to the iris blades to improve their sealing performance and stability under high extrusion pressure.

[0008] The detachable pressure-bearing iris extrusion nozzle structure can slide axially at the hot end nozzle of the 3D printing via an axial lifting mechanism. The lifting mechanism fixing seat is fixedly mounted in a ring at the lower end of the nozzle, and the lifting mechanism sliding seat is axially slidably mounted on the lifting mechanism fixing seat. The axial transmission screw is arranged vertically, with one end rotatably supported on the lifting mechanism fixing seat and the other end connected to the transmission mechanism. The lifting mechanism sliding seat and the axial transmission screw are engaged by a threaded pair structure to convert the rotational motion of the axial transmission screw into the axial linear motion of the lifting mechanism sliding seat. The transmission mechanism drives the axial transmission screw to rotate and achieves electrical control through an external circuit. The lifting mechanism protective housing covers the outside of the axial transmission screw and the transmission mechanism to protect the internal components of the lifting mechanism.

[0009] The iris fixing base plate is a ring-shaped structure with a through material extrusion channel at its center. This base plate is used to install and support the iris blades and related transmission components. It is smoothly connected to the lower end of the lifting mechanism's sliding seat, ensuring the fixing plate can slide up and down with the lifting mechanism. The iris shell is fixedly connected to the iris fixing base plate via a slot, locking the axial movement of the entire iris mechanism. Eight embedded column-type pressure-bearing iris blades are arranged closely together along the circumference. The blades are coated with an anti-stick coating to ensure only relative sliding occurs between the blades during the entire scaling process. The metal spring sheet... Fixedly installed on one side that is always close to the other blade, eliminating gaps and ensuring that material is extruded only from the extrusion channel; each iris blade has an embedded column structure inside, which cooperates with the arc-shaped and straight sliding grooves set on the iris drive moving plate and the iris fixing base plate, so that the iris blades open and close synchronously when the iris drive moving plate rotates; the iris drive moving plate is coaxially set on the upper side of the iris fixing base plate, and maintains relative rotation with the iris fixing base plate but restricts axial displacement through an axial limiting structure; a low thermal conductivity connection structure is set between the fan-shaped worm gear section and the iris fixing base plate along the circumferential direction. Multiple spaced-apart heat-insulating connecting columns are fixed at one end to the iris fixing plate and at the other end to the sector-shaped worm gear to reduce heat transfer from the iris fixing plate to the sector-shaped worm gear; an annular ceramic heat-insulating gasket is provided between the back of the sector-shaped worm gear section and the worm support seat to block heat conduction from the sector-shaped worm gear section to the transmission cavity; an air heat-insulating cavity is formed between the back of the sector-shaped worm gear section and the worm gear protective housing, and a heat dissipation hole is provided on the side away from the heating module to reduce the operating temperature of the transmission mechanism; the sector-shaped worm gear section meshes with the worm gear drive shaft; the worm gear The drive shaft is supported by bearings and installed inside the worm gear protective housing, and is connected to the output shaft of the reduction gear motor. This allows the rotational motion of the reduction gear motor to be converted into the angular displacement of the iris drive disk via worm gear transmission. The radial limiting sleeve of the iris blade is fitted on the outside of the iris blade and fixedly mounted on the iris shell to limit the maximum radial displacement of the iris blade and prevent the iris blade from over-opening or becoming structurally unstable under pressure. The worm gear protective housing is fixedly mounted on the iris shell to protect and lubricate the worm gear and worm wheel transmission components.

[0010] A method for using a pressure-bearing iris variable aperture extrusion nozzle for 3D printing includes the following steps:

[0011] (1) The printing material is introduced into the hot end system through the pneumatic connector. The printing material is axially conveyed along the polytetrafluoroethylene feed tube and initially guided and positioned in the heat dissipation tube to avoid the material from shifting or bending in the cold end area.

[0012] (2) During the material conveying process, the cooling fan continuously provides cooling airflow to the heat dissipation pipe, which forces the cooling of the heat dissipation pipe and the upper end of the throat pipe, thereby inhibiting the heat conduction to the polytetrafluoroethylene guide pipe and ensuring that the material remains in a solid or semi-solid state before entering the heating zone.

[0013] (3) The printing material enters the throat tube from the lower end of the polytetrafluoroethylene feed tube, and the nozzle is pre-tightened axially by the sealing metal spring set at the connection between the throat tube and the nozzle, so as to form a reliable seal between the throat tube and the nozzle to prevent the leakage of molten material.

[0014] (4) The nozzle and its internal material are heated by the heating module, so that the printing material gradually reaches the set melting temperature inside the nozzle, thereby forming an extrudable molten material.

[0015] (5) Before extrusion begins, the nozzle outlet inner diameter is constant. The inner diameter of the pressure-bearing iris variable aperture extrusion nozzle is adjusted according to printing requirements by a reduction gear motor driving a worm gear drive shaft to drive a sector worm wheel segment to drive the iris drive movable disk, thereby changing the inner diameter of the iris-like mechanism to meet printing requirements. Axial adjustment is performed through an axial lifting mechanism to raise the pressure-bearing iris variable aperture extrusion nozzle, so that one side of the embedded column-type pressure-bearing iris blade is tightly combined with the nozzle to meet the sealing and forming requirements required during the printing process.

[0016] (6) Under the action of the printing control command, the molten material flows along the nozzle axis under the action of the upstream feeding pressure, and is extruded from the nozzle outlet and then formed twice through the pressure-bearing iris variable aperture extrusion nozzle to form a continuous material filament or material flow.

[0017] (7) When the nozzle inner diameter needs to be changed during the printing process, the printing task enters the controlled pause state after the current path node is completed. The print head maintains the current height and slightly raises the Z axis. The extrusion motor stops forward feeding but maintains the position closed loop. The hot end of the pressure-bearing iris variable aperture extrusion nozzle is raised away from the printing area. The Z axis is raised to a safe height. The XY axis drives the hot end of the pressure-bearing iris variable aperture extrusion nozzle to leave the printing area. The hot end of the pressure-bearing iris variable aperture extrusion nozzle moves to the designated material changing and cleaning station. The material is pulled back, the extrusion motor rotates in the opposite direction, and the molten material is pulled back upward inside the nozzle. The material is stretched from the nozzle to the throat towards the cold end. The hot end of the pressure-bearing iris variable aperture extrusion nozzle moves to the corresponding position of the material cutting mechanism. The built-in cutter action mechanically cuts the material that has been pulled back. The extrusion motor rotates forward for a short time to squeeze out the old material remaining in the hot end of the pressure-bearing iris variable aperture extrusion nozzle. The nozzle is aligned with the cleaning tank to remove the material.

[0018] (8) After extrusion, axial adjustment is performed using the axial lifting mechanism to lower the pressure-bearing iris variable aperture extrusion nozzle to the designated position. The worm gear transmission shaft is driven by the reduction gear motor to drive the sector worm wheel segment to drive the iris drive movable disk, thereby changing the inner diameter of the iris-like mechanism. Then, the pressure-bearing iris variable aperture extrusion nozzle is raised to ensure that one side of the embedded column-type pressure-bearing iris blade is tightly engaged with the nozzle for the next printing.

[0019] (9) The extrusion motor rotates in the forward direction, and the material continues to be conveyed and melted, and is continuously extruded to a certain length; the pressure-bearing iris variable aperture extrusion nozzle reciprocates on the wiping nozzle structure to remove the unstable extrusion residue of the new material in the early stage and prevent filament hanging and dripping.

[0020] (10) The hot end of the entire 3D printed pressure-bearing iris variable aperture extrusion nozzle returns to the printing area, the Z-axis descends to the printing height, the extrusion motor resumes synchronization with the path, and the printing task continues to be executed.

[0021] A method and apparatus for using a pressure-bearing iris variable aperture extrusion nozzle for 3D printing has the following beneficial effects:

[0022] This invention, by setting up a pressure-bearing iris extrusion mechanism and combining it with a worm gear reduction drive, achieves continuous adjustment of the extrusion orifice diameter. This allows for precise adjustment of the extrusion flow rate during printing according to process requirements, effectively improving the flexibility and consistency of the printed product. Simultaneously, the embedded columnar pressure-bearing iris blades, with their pressure-bearing structure and the use of a clamping metal spring plate and limiting structure, maintain good sealing performance and structural stability even under high-temperature and high-pressure extrusion conditions, reducing the risk of material leakage and blockage. Furthermore, this invention designs the iris extrusion nozzle as a detachable module for easy maintenance and replacement, and uses an axial lifting mechanism to achieve precise adjustment of the nozzle position, improving the reliability and adaptability of the equipment. Overall, this invention features a simple structure, reliable transmission, high control precision, and low manufacturing and maintenance costs, making it suitable for multi-material, multi-condition 3D printing extrusion applications. Attached Figure Description

[0023] Figure 1 1. Main sectional view of the present invention;

[0024] Figure 2 A magnified front view of the pressure-bearing iris variable aperture extrusion nozzle of the present invention;

[0025] Figure 3 A cross-sectional enlarged schematic diagram of the pressure-bearing iris variable aperture extrusion nozzle of the present invention;

[0026] 1. Pneumatic connector, 2. Heat dissipation pipe, 3. Cooling fan, 4. Cooling fan bracket, 5. PTFE feed tube, 6. Throat, 7. Nozzle, 8. Detachable pressure-bearing iris extrusion nozzle assembly, 9. Axial lifting mechanism, 10. Heating module.

[0027] Among them, 8. The detachable pressure-bearing iris extrusion nozzle assembly includes: 801. worm gear drive shaft, 802. reduction gear motor, 803. worm gear protective housing, 804. annular heat-insulating ceramic gasket, 805. fan-shaped worm gear segment, 806. iris shell, 807. iris blade radial limiting sleeve, 808. iris drive moving plate, 809. iris fixing base plate, 810. iris rotation pivot, 811. embedded column-type pressure-bearing iris blade.

[0028] 9. The axial lifting mechanism includes: 901. Lifting mechanism fixed seat, 902. Lifting sliding seat, 903. Axial transmission shaft, 904. Lifting mechanism protective housing cover. Detailed Implementation

[0029] The following description provides a detailed explanation of the embodiments of the present invention in a step-by-step manner. This description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0030] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limiting this invention.

[0031] A device for a pressure-bearing iris variable aperture extrusion nozzle for 3D printing, such as Figure 1As shown, it includes a pneumatic connector 1, a heat dissipation pipe 2, a heat dissipation fan 3, a heat dissipation fan bracket 4, a polytetrafluoroethylene feed pipe 5, a throat 6, a nozzle 7, a detachable pressure-bearing iris extrusion nozzle assembly 8, an axial lifting mechanism 9, a heating module 10, and a control system (not shown in the figure). The 3D printing hot end comprises interconnected components from top to bottom. A pneumatic connector 1 is located at the upper end of the heat dissipation pipe 2, and the two are connected by threads. The inner cavity of the pneumatic connector 1 communicates with the axial through-hole of the heat dissipation pipe 2, used for axial positioning and sealing of the polytetrafluoroethylene (PTFE) feed tube 5. The PTFE feed tube 5 is located within the inner cavity of the heat dissipation pipe 2, its upper end is pressed and fixed by the pneumatic connector 1, and its lower end extends to the outside of the throat tube 6, used to guide the printing material downwards and isolate heat transfer upwards. The throat tube 6 is located at the lower end of the heat dissipation pipe 2 and connected to the nozzle, the two being connected by threads. The throat tube 6 has a low thermal conductivity structure, and its inner cavity communicates with the lower end of the PTFE feed tube 5 to achieve the transition of material transport from the cold end to the hot end. The nozzle 7 is located at the lower end of the throat tube 6, and the nozzle 7 and throat tube 6 are fixed by a threaded connection. Their axial through-holes are interconnected, used to extrude molten material into shape. The heating module 10 is located outside the nozzle 7. The heating module 10 is fixedly connected to the nozzle 7 via fasteners or a heating block structure (not shown in the figure). The heating module 10 is used to heat the nozzle 7 and its internal material, so that the printing material reaches a molten state. The cooling fan 3 is located on the outside of the heat dissipation pipe and is fixedly connected to the heat dissipation pipe 2 via the cooling fan bracket 4. The air outlet direction of the cooling fan 3 is towards the outer surface of the heat dissipation pipe 2, which is used to provide forced air cooling for the heat dissipation pipe 2. The sealing metal spring (not shown in the figure) is located at the connection between the throat 6 and the nozzle 7. The sealing metal spring (not shown in the figure) generates an axial elastic preload when the nozzle 7 is tightened, so as to compensate for thermal expansion and improve the sealing performance of the connection and prevent leakage of molten material. The clamping metal plate (not shown in the figure) is located at the bottom of the nozzle 7 and is used to apply axial or radial preload to the embedded column-type pressure-bearing iris blade 811 to improve the sealing performance and stability of the embedded column-type pressure-bearing iris blade 811 under high extrusion pressure.

[0032] The detachable pressure-bearing iris extrusion nozzle 8 can slide axially at the hot end nozzle of the 3D printing via an axial lifting mechanism 9. The lifting mechanism fixing seat 901 is annularly fixed around the nozzle 7, and the lifting mechanism sliding seat 902 is axially slidably disposed within the lifting mechanism fixing seat 901. The axial transmission screw 903 is arranged vertically, with one end rotatably supported on the lifting mechanism fixing seat 901, and the other end connected to a transmission mechanism (not shown in the figure). The lifting mechanism sliding seat 902 and the axial transmission screw... The moving lead screws 903 are engaged by a threaded pair structure to convert the rotational motion of the axial transmission lead screws 903 into the axial linear motion of the lifting mechanism sliding seat 902; the transmission mechanism (not shown in the figure) is used to drive the shaft (not shown in the figure) to transmit power to the axial transmission lead screws 903, and realizes electrical control through an external circuit (not shown in the figure); the lifting mechanism protective housing cover 904 is provided on the outside of the axial transmission lead screws 903 and the transmission mechanism (not shown in the figure) to protect the internal components of the lifting mechanism.

[0033] The iris fixing base plate 809 has a ring-shaped structure with a through material extrusion channel at its center. The iris fixing base plate 809 is used to install and support the embedded column-type pressure-bearing iris blades 811 and related transmission components. The iris fixing base plate 809 is smoothly connected to the lower end of the lifting mechanism sliding seat 902, ensuring that the iris fixing base plate 809 can slide up and down with the lifting mechanism 9. The iris shell 806 is fixedly connected to the iris fixing base plate 809 by a slot, locking the axial movement of the entire iris mechanism 9. Eight embedded column-type pressure-bearing iris blades 811 are arranged closely together along the circumference. The blades are coated with an anti-stick coating to ensure that only relative sliding occurs between the blades during the entire shrinking and enlarging process. The metal spring... The blade (not shown in the figure) is fixedly installed on the side of the blade that is always close to the next blade, eliminating gaps and ensuring that the material is extruded only from the extrusion channel; each iris blade has an embedded column groove inside, and the iris rotation pivot 810 cooperates with the arc groove and straight groove set on the iris drive movable disk 808 and the iris fixed base disk 809, so that when the iris drive movable disk 808 rotates, it drives the embedded column-type pressure-bearing iris blade 811 to open and close synchronously; the iris drive movable disk 808 is coaxially set on the upper side of the iris fixed base disk 809, and maintains relative rotation with the iris fixed base disk 809 through an axial limiting structure, but restricts axial displacement; the sector worm gear section 805 is between the iris fixed base disk 809 and the iris fixed base disk 809. A low thermal conductivity connection structure is provided, with multiple heat-insulating connecting columns spaced circumferentially. One end of each column is fixed to the iris fixing plate, and the other end is connected to a sector-shaped worm gear to reduce heat transfer from the iris fixing plate to the sector-shaped worm gear. An annular ceramic heat-insulating gasket 804 is provided between the back of the sector-shaped worm gear segment 805 and the worm support seat to block heat conduction from the sector-shaped worm gear segment 805 to the transmission cavity. An air-insulating cavity is formed between the back of the sector-shaped worm gear segment 805 and the worm gear protective housing 803, and a heat dissipation hole is provided on the side away from the heating module to reduce the operating temperature of the transmission mechanism. The sector-shaped worm gear segment 805 meshes with the worm gear drive shaft 801. The worm gear drive shaft 801 is mounted inside the worm gear protective housing 803 with bearing support, and is connected to the output shaft of the reduction gear motor 802 for transmission, so that the rotational motion of the reduction gear motor is converted into the angular displacement of the iris drive movable disk 808 through worm gear transmission; the radial limiting sleeve 807 of the iris blade is sleeved on the outside of the embedded pressure-bearing iris blade 811 and fixedly mounted on the iris housing 806, which is used to limit the maximum radial displacement of the iris blade and prevent the iris blade from over-opening or structurally unstable under pressure; the worm gear protective housing 803 is fixedly mounted on the iris housing 806, which is used to protect and lubricate the worm and worm gear transmission components.

[0034] A method for using a pressure-bearing iris variable aperture extrusion nozzle for 3D printing includes the following steps:

[0035] (1) The printing material is introduced into the hot end system through the pneumatic connector 1. The printing material is axially conveyed along the polytetrafluoroethylene feed tube 5 and initially guided and positioned in the heat dissipation tube 2 to avoid the material from shifting or bending in the cold end area.

[0036] (2) During the material transport process, the cooling fan 3 continuously provides cooling airflow to the heat dissipation pipe 2, which forces the cooling of the heat dissipation pipe 2 and the upper end of the throat pipe 6 to suppress the heat conduction to the polytetrafluoroethylene guide pipe 5, and ensure that the material remains in a solid or semi-solid state before entering the heating zone.

[0037] (3) The printing material enters the throat 6 from the lower end of the polytetrafluoroethylene feed tube 5, and the nozzle 7 is axially pre-tightened by the sealing metal spring (not shown in the figure) set at the connection between the throat 6 and the nozzle 7, so that a reliable seal is formed between the throat 6 and the nozzle 7 to prevent the leakage of molten material.

[0038] (4) The nozzle 7 and its internal material are heated by the heating module 10, so that the printing material gradually reaches the set melting temperature inside the nozzle 7, thereby forming an extrudable molten material.

[0039] (5) Before extrusion begins, the inner diameter of nozzle 7 is constant. The inner diameter of the pressure-bearing iris variable aperture extrusion nozzle 8 is adjusted according to printing requirements by the reduction gear motor 802 driving the worm gear drive shaft 801 to drive the fan-shaped worm wheel section 805 to drive the iris drive movable disk 907, so that the iris-like mechanism changes its inner diameter to meet printing requirements. Axial adjustment is performed by the axial lifting mechanism 9 to adjust the pressure-bearing iris variable aperture extrusion nozzle 8 to rise, so that one side of the embedded column-type pressure-bearing iris blade 811 is tightly fitted with the clamping metal spring plate (not shown in the figure) on one side of nozzle 7 to meet the sealing and forming requirements required during the printing process.

[0040] (6) Under the action of the printing control command, the molten material flows along the axial direction of the nozzle 7 under the action of the upstream feeding pressure, and is extruded from the nozzle outlet and then formed twice through the pressure-bearing iris variable aperture extrusion nozzle 8 to form a continuous material filament or material flow.

[0041] (7) When the inner diameter of the detachable pressure-bearing iris extrusion nozzle 8 needs to be replaced during the printing process, the printing task enters a controlled pause state after the current path node is completed. The print head (not shown in the figure) maintains the current height and slightly raises the Z-axis. The extrusion motor (not shown in the figure) stops forward feeding but maintains a closed-loop position. The hot end of the pressure-bearing iris variable aperture extrusion nozzle is raised away from the printing area, the Z-axis is raised to a safe height, and the XY axis drives the hot end of the pressure-bearing iris variable aperture extrusion nozzle to leave the printing area. The hot end of the pressure-bearing iris variable aperture extrusion nozzle moves to Designated material changing and cleaning stations; material is drawn back, the extrusion motor rotates in the reverse direction, and the molten material is pulled upward inside the detachable pressure-bearing iris extrusion nozzle 8. The material is stretched from the nozzle 7 to the throat 6 towards the cold end; the hot end of the pressure-bearing iris variable aperture extrusion nozzle moves to the corresponding position of the material cutting mechanism (not shown in the figure), and the built-in cutter mechanically cuts the drawn-back material; the extrusion motor rotates forward for a short time to extrude the old material remaining in the hot end of the pressure-bearing iris variable aperture extrusion nozzle, and the detachable pressure-bearing iris extrusion nozzle 8 is aligned with the cleaning tank to remove the material.

[0042] (8) After extrusion, axial adjustment is performed by axial lifting mechanism 9 to adjust the pressure-bearing iris variable aperture extrusion nozzle 8 to descend to the specified position. The worm gear transmission shaft 801 is driven by reduction gear motor 802 to drive the fan-shaped worm wheel section 805 to drive the iris drive moving disk 808 to change the inner diameter of the iris-like mechanism. Then, the pressure-bearing iris variable aperture extrusion nozzle 8 is adjusted to rise, so that one side of the embedded column-type pressure-bearing iris blade 811 is tightly connected with the pressing metal spring plate (not shown in the figure) on the side of the nozzle 7 for the next printing.

[0043] (9) The extrusion motor (not shown in the figure) rotates in the forward direction, and the material continues to be conveyed and melted, and is continuously extruded to a certain length; the pressure-bearing iris variable aperture extrusion nozzle 8 reciprocates on the wiping nozzle structure to remove the unstable extrusion residue of the new material in the early stage and prevent filaments and dripping.

[0044] (10) The hot end of the entire pressure-bearing iris variable aperture extrusion nozzle returns to the printing area, the Z-axis descends to the printing height, the extrusion motor resumes synchronization with the path, and the printing task continues to be executed.

Claims

1. A method of using a pressure-bearing iris variable aperture extrusion nozzle for 3D printing, characterized in that: Printing material is introduced into the hot-end system via a pneumatic connector, allowing it to enter the throat via a PTFE feed tube. A cooling fan forces cooling of the heat dissipation tube and the upper end of the throat to suppress upward heat conduction. A sealing metal spring forms an axial seal between the throat and the nozzle. A heating module melts the material inside the nozzle. Before extrusion, a drive gear motor rotates a sector worm gear via a worm drive shaft, which in turn drives the iris drive disc to synchronously open and close the pressure-bearing iris blades to adjust the through-hole diameter. An axial lifting mechanism ensures a sealed fit between the iris blades and the nozzle outlet face. Under feeding pressure, the molten material is extruded through the nozzle and enters the pressure-bearing iris variable-aperture extrusion nozzle for secondary forming, creating a continuous material flow. When the aperture needs to be changed, the nozzle is removed from the printing area, and residual material is retracted and removed. The iris aperture is then readjusted, and the axial seal is restored, allowing the extrusion system to return to the printing position and continue printing.

2. The device配套的装置 for the method of using a pressure-bearing iris variable aperture extrusion nozzle for 3D printing according to claim 1, characterized in that: The 3D printing hot end nozzle consists of a pneumatic connector, a heat dissipation pipe, a polytetrafluoroethylene feed tube, a throat, a nozzle, a cooling fan, a cooling fan bracket, a heating module, a sealing metal spring, a detachable pressure-bearing iris extrusion nozzle assembly, and an axial lifting mechanism. It should be noted that the part "配套的装置" in the original text may need to be adjusted according to the actual context to make the translation more accurate. Here, a literal translation is provided first.

3. The apparatus for a pressure-bearing iris variable aperture extrusion nozzle for 3D printing as described in claim 2, characterized in that: The detachable pressure-bearing iris extrusion nozzle assembly includes: an iris fixing base plate, an iris driving movable plate, an embedded column-type pressure-bearing iris blade, a metal spring, a clamping metal spring plate, an iris shell, an annular heat-insulating ceramic gasket, a fan-shaped worm gear section, a worm drive shaft, a reduction gear motor, a worm gear protective shell, and a radial limiting sleeve for the iris blade.

4. The apparatus for a pressure-bearing iris variable aperture extrusion nozzle for 3D printing as described in claim 3, characterized in that: The axial lifting mechanism includes: a lifting mechanism fixed seat, a lifting mechanism sliding seat, an axial transmission screw, a lifting mechanism protective housing, a transmission mechanism, and an external circuit.

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