Variable-diameter nozzle suitable for melt extrusion manufacturing and application of variable-diameter nozzle

Abstract

The invention discloses a variable-diameter nozzle suitable for melt extrusion manufacturing and application thereof, and has the following beneficial effects: (1) stepless adjustment of the aperture of the nozzle with the diameter of 0-5mm can be realized under the condition that a printing head is not switched, the diameter of the nozzle can be flexibly adjusted according to printing requirements, and the printing efficiency is improved; the problem that the diameter of the nozzle is fixed in the prior art is effectively solved; (2) the fixed ring is connected with the additive manufacturing device through threads, so that the universality of the variable-diameter nozzle is improved; (3) the closed teeth are designed in a biconical shape, air holes can be prevented from being generated at a feeding port, and collision between a discharging port and printed parts can be avoided; (4) small-diameter nozzles are adopted for high-precision printing on the outer wall, large-diameter nozzles are switched for high-speed forming in internal filling, and the surface quality and efficiency are improved; and the runner is automatically closed in a pumpback path, so that the problem of melt casting is effectively solved. According to the invention, collaborative optimization of printing precision, efficiency and material economy is realized, and an innovative solution is provided for melt extrusion manufacturing.

Description

Technical Field

[0001] The present invention relates to the technical field of melt extrusion additive manufacturing, and in particular to a variable diameter nozzle suitable for melt extrusion manufacturing and an application thereof. Background Art

[0002] Melt extrusion additive manufacturing technology is a 3D printing technology based on the principle of layer-by-layer stacking. It originated in the 1990s. It melts filamentous or granular materials by heating, then extrudes and stacks them layer by layer to form them. This technology is widely used due to its simple equipment structure, low cost and easy operation. It is especially suitable for making objects with complex structures. Although there are problems such as low printing accuracy, with the continuous improvement of technology, it has shown broad application prospects in industrial manufacturing, education, medical care and other fields.

[0003] In the melt extrusion additive manufacturing technology, the nozzle diameter used directly determines the surface accuracy and molding efficiency of the molded parts. The nozzles currently used have fixed sizes. In order to obtain high-quality surfaces, small-diameter nozzles are usually used, but this greatly reduces the molding efficiency. When a large-diameter nozzle is used, the molding efficiency is greatly improved, but due to the limitations of the technology itself, obvious step patterns will appear on the surface, and good surface quality cannot be obtained. If you want to switch between multiple nozzles during the printing process, you need to pause the printing, and the diameter cannot be continuously changed, which affects the continuity of the printing. At present, moving or rotating blocks are also used to change the nozzle width, but changing the printing direction will cause the width to change, affecting consistency.

[0004] Variable diameter nozzles must be able to adjust continuously in real time to dynamically adjust the nozzle diameter during the printing process to meet the needs of different printing areas (such as the outer wall and filling). At the same time, the nozzle should be able to achieve a wide range of diameter changes, such as continuous adjustment from 0mm to 5mm, to adapt to different scenarios from fine surface to fast filling. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In view of the deficiencies of the prior art, the present invention provides a variable diameter nozzle suitable for melt extrusion manufacturing and its application, which can solve the above technical problems.

[0007] (2) Technical solution

[0008] In order to solve the above technical problems, the present invention provides the following technical solution: a variable diameter nozzle suitable for melt extrusion manufacturing, comprising: a driving mechanism and a variable diameter nozzle structure, wherein the variable diameter nozzle structure includes a moving coil, a fixed coil and a plurality of closed teeth, the driving mechanism is connected to the moving coil, the fixed coil and the moving coil are coaxial, each closed tooth is connected to the moving coil and the fixed coil, the plurality of closed teeth are distributed in a circle and form a channel for the molten material to pass through, the upper and lower ends of the fixed coil are respectively provided with a first feed port and a first discharge port, the first discharge port is arranged corresponding to the channel above and below, and the driving mechanism is used to drive the moving coil to rotate to change the positions of the plurality of closed teeth and change the diameter of the channel.

[0009] Preferably, the moving coil is provided with a first screw and the fixed coil is provided with a second screw, the closing tooth is connected to the moving coil by the first screw, and the closing tooth is connected to the fixed coil by the second screw; the moving coil is provided with a plurality of first sliding grooves, and the fixed coil is provided with a plurality of second sliding grooves, the plurality of first sliding grooves and the plurality of second sliding grooves are all distributed in a circular manner, and the number of the first sliding grooves and the number of the second sliding grooves are the same as the number of the closing teeth.

[0010] Preferably, a square boss is provided at the upper rear end of the closing tooth, the first screw is connected to the square boss, the first slide groove is a square slide groove, the square boss is located in the first slide groove, and the closing tooth moves in the first slide groove through the square boss.

[0011] Preferably, the upper part of the closing tooth is connected to the second screw near the front end, the second slide groove is an arc slide groove, and a cylinder is provided in the middle of the second screw. The cylinder is located in the second slide groove, and the closing tooth moves in the second slide groove through the cylinder.

[0012] Preferably, the upper front ends of the plurality of closed teeth form a concave second feed opening, the second feed opening is arranged corresponding to the upper end of the channel, and the second feed opening is in the shape of a conical funnel.

[0013] Preferably, the front ends of the lower parts of the multiple closed teeth form a downwardly convex second discharge port, the second discharge port is arranged corresponding to the lower end of the channel, and the second discharge port is in the shape of a conical funnel.

[0014] Preferably, the first feed port is connected to the nozzle of the additive manufacturing device in the form of a threaded connection.

[0015] Preferably, the driving mechanism includes a steering gear, a driving gear and a driving disc, the moving coil is connected to the driving disc via a third screw, the driving gear is connected to the steering gear via a fourth screw, and the driving gear is meshed with the driving disc.

[0016] In order to solve the above technical problems, the present invention provides another technical solution as follows: an application of a variable diameter nozzle suitable for melt extrusion manufacturing, and applying the variable diameter nozzle suitable for melt extrusion manufacturing of the above technical solution to melt extrusion additive manufacturing.

[0017] Preferably, the application of a variable diameter nozzle suitable for melt extrusion manufacturing comprises the following steps:

[0018] S11, import the model file to be printed into the slicing software and perform model preprocessing;

[0019] S12, the slicing software recognizes the characteristics of the model;

[0020] S13, the slicing software slices the model into layers, sets layer height and support, and generates layer-by-layer paths;

[0021] S14. Add two virtual extruders in the slicing software: a first extruder and a second extruder, wherein the first extruder is set to have a small-diameter nozzle and the second extruder is set to have a large-diameter nozzle;

[0022] S15. In the slicing software, set the outer wall to be printed using the first extruder and the filling to be printed using the second extruder;

[0023] S16. Replacing the instruction for switching the extruder with an instruction for controlling the drive mechanism in the printing control code, so that the nozzle diameter is switched when the step of switching the extruder is performed;

[0024] S17. Adding a temperature control instruction and a speed control instruction to the print control code to control the printing temperature and printing speed of the first extruder and the second extruder, wherein the printing temperature of the second extruder is higher than the printing temperature of the first extruder, and the printing speed of the first extruder is higher than the printing speed of the second extruder;

[0025] S18: Generate the final printing control code, calibrate the printing platform, start the printing task and monitor it.

[0026] (3) Beneficial effects

[0027] Compared with the prior art, the present invention provides a variable diameter nozzle suitable for melt extrusion manufacturing and its application, which has the following beneficial effects: the present invention includes a driving mechanism and a variable diameter nozzle structure, wherein the variable diameter nozzle structure includes a moving coil, a fixed coil and a plurality of closed teeth, and the driving mechanism can drive the moving coil to rotate to change the position of the plurality of closed teeth, thereby changing the diameter of the channel for the molten material to pass through. Through the above method, the present invention can realize stepless adjustment of the nozzle diameter, and the variable range of the nozzle diameter is 0-5mm. The nozzle diameter can be flexibly adjusted according to printing requirements, thereby improving printing accuracy and quality, effectively solving the problem of fixed nozzle diameter in the prior art, achieving a breakthrough in variable diameter nozzle technology, and better adapting to meet the needs of different scenarios from fine surfaces to rapid filling. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A cross-sectional view of a variable diameter nozzle suitable for melt extrusion manufacturing in one embodiment of the present invention;

[0029] Figure 2 An exploded view of a variable diameter nozzle suitable for melt extrusion manufacturing in one embodiment of the present invention;

[0030] Figure 3 Schematic diagram of the motion trajectory of the closed gear relative to the moving coil and the fixed coil in one embodiment of the present invention;

[0031] Figure 4 A perspective view of a variable diameter nozzle structure and a drive disk in one embodiment of the present invention;

[0032] Figure 5 is a first perspective view of a plurality of closed teeth in one embodiment of the present invention;

[0033] Figure 6 is a second perspective view of a plurality of closed teeth in one embodiment of the present invention;

[0034] Figure 7 A top view of a closed tooth according to an embodiment of the present invention;

[0035] Figure 8 is a three-dimensional diagram of a closed tooth in one embodiment of the present invention;

[0036] Figure 9 is a perspective view of a second screw in one embodiment of the present invention;

[0037] Figure 10 A top view of a variable diameter nozzle suitable for melt extrusion manufacturing in a closed state in one embodiment of the present invention;

[0038] Figure 11 A top view of a variable diameter nozzle suitable for melt extrusion manufacturing in an open state according to one embodiment of the present invention;

[0039] Figure 12 A perspective view of a variable diameter nozzle suitable for melt extrusion manufacturing in another embodiment of the present invention;

[0040] Figure 13 The figure is a schematic flow chart of the application of a variable diameter nozzle suitable for melt extrusion manufacturing in one embodiment of the present invention.

[0041] The numbers in the figure are: 1 first screw, 2 second screw, 3 fixed coil, 4 moving coil, 5 closed tooth, 6 driving gear, 7 servo, 8 driving plate, 9 fourth screw, 10 third screw, 11 driving connecting rod, 12 channel, 13 first feed port, 14 first chute, 15 second chute, 16 square boss, 17 cylinder, 18 second feed port, 19 second discharge port, 20 motion trajectory in the moving coil, 21 motion trajectory in the fixed coil. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] The present invention provides a variable diameter nozzle suitable for melt extrusion manufacturing, including a drive mechanism and a variable diameter nozzle structure. The variable diameter nozzle structure includes a moving coil 4, a fixed coil 3 and a plurality of closed teeth 5, and the drive mechanism is connected to the moving coil 4; the fixed coil 3 and the moving coil 4 are coaxial, and the moving coil 4 and the fixed coil 3 have a clearance fit and good coaxiality, so that the moving coil 4 can smoothly rotate around the fixed coil 3; each closed tooth 5 is connected to the moving coil 4 and the fixed coil 3, and the plurality of closed teeth 5 are distributed in a circle and form a channel 12 for the molten material to pass through. The upper end and the lower end of the fixed coil 3 are respectively provided with a first feed port 13 and a first discharge port, and the first discharge port and the channel 12 are arranged in correspondence with each other; the drive mechanism is used to drive the moving coil 4 to rotate to change the position of the plurality of closed teeth 5, that is, to change the diameter of the channel 12 formed by the plurality of closed teeth 5, that is, to change the nozzle diameter to achieve variable diameter printing.

[0044] Specifically, the moving coil 4 is provided with a first screw 1, and the fixed coil 3 is provided with a second screw 2. The closing teeth 5 are connected to the moving coil 4 via the first screw 1, and to the fixed coil 3 via the second screw 2. The moving coil 4 is provided with a plurality of first chute grooves 14, and the fixed coil 3 is provided with a plurality of second chute grooves 15. The plurality of first chute grooves 14 and the plurality of second chute grooves 15 are distributed circumferentially, and the number of first chute grooves 14 and the number of second chute grooves 15 are the same as the number of closing teeth 5. In this embodiment, the number of closing teeth 5 is twelve; in other embodiments, the number of closing teeth 5 may also be sixteen or another number, without further limitation.

[0045] Furthermore, in this embodiment, a square boss 16 is provided at the upper rear end of the closing tooth 5. The first screw 1 is connected to the square boss 16. The first chute 14 is a square chute. The square boss 16 is located within the first chute 14 and can move freely. The closing tooth 5 moves within the first chute 14 via the square boss 16. It will be understood that the top diameter of the first screw 1 is larger than the maximum width of the first chute 14 to prevent the closing tooth 5 from falling off the movable coil 4. Furthermore, the closing tooth 5 is tightly fitted to the bottom surface of the movable coil 4 to prevent radial leakage of molten material.

[0046] Furthermore, in this embodiment, the upper portion of the closing tooth 5, near the front end, is connected to the second screw 2. The second chute 15 is a circular arc chute. A cylindrical body 17 is provided in the middle of the second screw 2. The cylindrical body 17 is located within the second chute 15, and the closing tooth 5 moves within the second chute 15 via the cylindrical body 17. The top diameter of the second screw 2 is larger than the maximum width of the second chute 15, thereby preventing the closing tooth 5 from falling off the fixed ring 3. The second screw 2 can preferably be a shoulder screw, allowing the closing tooth 5 to move freely within the second chute 15 of the fixed ring 3.

[0047] It can be understood that the driving mechanism provides power to drive the moving coil 4 to perform circular motion, so that the square boss 16 of the closing tooth 5 moves relative to the first sliding groove 14 of the moving coil 4. In this embodiment, Figure 3 As shown, the motion trajectory 20 of the closing tooth 5 in the moving coil is the linear motion of the square boss 16 in the square chute (first chute 14); when the square boss 16 moves relatively to contact the width side of the first chute 14, the closing tooth 5 is driven to move synchronously with the continued rotation of the moving coil 4. At this time, the closing tooth 5 drives the cylindrical body 17 of the second screw 2 connected thereto to move in the second chute 15, as shown in FIG. Figure 3 As shown, the motion trajectory 21 of the closed tooth 5 in the fixed ring 3 (i.e., the motion trajectory of the corresponding cylinder 17 in the fixed ring 3) is the circular motion of the cylinder 17 in the arc chute (the second chute 15); that is, the rotation of the moving ring 4 can synchronously drive multiple closed teeth 5 to move and synchronously change the positions of multiple closed teeth 5. The movement of multiple closed teeth 5 is achieved through the above-mentioned linkage method, thereby changing the diameter of the channel 12 for the molten material to pass through, that is, changing the diameter of the nozzle. In addition, when it is necessary to reversely adjust the diameter of the channel 12, similarly, the driving mechanism can be used to drive the moving ring 4 to rotate in the opposite direction, which will not be described here. Figure 10 The variable diameter nozzle of the present invention is shown in a closed state, that is, the diameter of the channel 12 is 0 at this time; in addition, as shown in FIG. Figure 11The variable diameter nozzle of the present invention is shown in an open state. The variable diameter nozzle of the present invention can achieve a maximum diameter of the channel 12 of 5 mm, that is, the nozzle diameter of the present invention can be infinitely adjusted in a variable range of 0-5 mm.

[0048] Preferably, the first feed port 13 of the fixed ring 3 is connected to the nozzle of the additive manufacturing device using a threaded connection. The additive manufacturing device adopts molten material extrusion manufacturing technology. The threaded connection form used by the first feed port 13 of the present invention is consistent with the nozzle thread size commonly used in various additive manufacturing devices such as FDM and FGF printers on the market. Through the above-mentioned threaded connection method, the versatility of the variable diameter nozzle of the present invention is improved, making the present invention applicable to multiple types of additive manufacturing devices (i.e., melt extrusion equipment). In addition, in other embodiments, the first feed port 13 of the fixed ring 3 can also be designed as an integrated whole with the nozzle of the additive manufacturing device.

[0049] Preferably, in this embodiment, the upper front ends of the plurality of closed teeth 5 form a concave second feed port 18, and the second feed port 18 is arranged corresponding to the upper end of the channel 12, and the second feed port 18 is in the shape of a conical funnel. It can be understood that the molten material enters the channel 12 in sequence through the nozzle of the additive manufacturing device, the first feed port 13 of the fixed ring 3, the first discharge port, and the second feed port 18 of the closed teeth 5. The present invention is able to extrude the molten material by providing a concave conical funnel-shaped second feed port 18, so that the molten material entering the variable diameter nozzle is gradually compressed into the inside of the nozzle port to prevent the formation of air holes. In addition, the above-mentioned driving mechanism and the variable diameter nozzle structure of the present invention can be specifically arranged as a whole on a mounting frame, and the mounting frame is connected to the motion device of the additive manufacturing device, so that the motion device can drive the nozzle of the additive manufacturing device, the driving mechanism of the present invention, and the variable diameter nozzle structure to move synchronously.

[0050] Furthermore, preferably, the lower front ends of the multiple closed teeth 5 form a downwardly convex second discharge port 19, which is arranged corresponding to the lower end of the channel 12 and has a conical funnel shape. After the molten material enters the channel 12 formed by the closed teeth 5, it is extruded from the second discharge port 19 and further accumulated on the printing platform to complete the printing. The provision of the conical funnel-shaped second discharge port 19 in the present invention effectively avoids the risk of collision between the variable diameter nozzle and the printed part model caused by the movement of the print head during printing.

[0051] It can be understood that, in one embodiment, the process of various additive manufacturing devices on the market using the variable diameter nozzle of the present invention for printing is as follows: the first feed port 13 of the fixed ring 3 is threadedly connected to the nozzle (i.e., the extrusion end) of the additive manufacturing device; the molten material for printing passes through the fixed ring 3 and enters the closed tooth 5 structure with a conical surface (i.e., the second feed port 18 corresponding to the conical funnel shape); then, the molten material is extruded through the variable diameter channel 12 formed by the circumferential distribution of multiple closed teeth 5, and finally accumulated on the printing platform to complete the printing, thereby realizing variable diameter printing.

[0052] In addition, if Figure 2 As shown, in one embodiment, the driving mechanism specifically includes a steering gear 7, a driving gear 6 and a driving disc 8. The moving coil 4 is connected to the driving disc 8 via a third screw 10, and the driving gear 6 is connected to the steering gear 7 via a fourth screw 9. The driving gear 6 is meshed with the driving disc 8. It can be understood that the steering gear 7 drives the driving gear 6 to rotate, and the driving gear 6 drives the driving disc 8 to rotate. The rotation of the driving disc 8 drives the moving coil 4 to rotate. In addition, as Figure 12 As shown, in another embodiment, the driving mechanism may also include a connected servo 7 and a driving connecting rod 11, and the dynamic coil 4 is driven to rotate by the driving connecting rod 11. Of course, the driving mechanism may also adopt other driving device forms to achieve the driving of the dynamic coil to rotate, and there is no excessive limitation here.

[0053] Preferably, since the fixed coil 3 and the closing teeth 5 are in direct contact with the molten material, the materials of the fixed coil 3 and the closing teeth 5 are preferably made of high thermal conductivity materials to ensure that the molten material is extruded within a suitable temperature range to ensure the printing effect; at the same time, the moving coil 4 and the driving disk 8 will not directly contact the molten material, but both will be in direct or indirect contact with the fixed coil 3 and the closing teeth 5, so the moving coil 4 and the driving disk 8 are preferably made of insulating materials to prevent the dissipation of heating temperature.

[0054] The present invention also provides an application of a variable diameter nozzle suitable for melt extrusion manufacturing, by applying the above-mentioned variable diameter nozzle suitable for melt extrusion manufacturing to melt extrusion additive manufacturing. It can be understood that the variable diameter nozzle of the present invention is a nozzle installed in an additive manufacturing device (i.e., the end section of the extrusion head of a 3D printing machine), and the additive manufacturing device extrudes the molten material according to the slicing file instruction. The extruded molten material passes through the internal pipe of the fixed ring 3 structure threadedly connected to the extrusion head and enters the closed tooth 5 structure with a tapered surface (i.e., the second feed port 18 corresponding to the tapered funnel); Subsequently, the molten material is extruded through the variable diameter channel 12 formed by the circumferential distribution of multiple closed teeth 5, and the nozzle diameter is changed under the control of the slicing file instruction code and the printing is completed by stacking layer by layer on the printing platform.

[0055] Preferably, in one embodiment, the present invention is applicable to the application of a variable diameter nozzle manufactured by melt extrusion, specifically comprising the following steps S11-S18:

[0056] S11. Import the model file to be printed into the slicing software, perform model inspection and model preprocessing, repair model defects, and adjust the size and direction.

[0057] S12. The slicing software recognizes the features of the model.

[0058] S13. The slicing software slices the model into layers, sets layer height and support, and generates layer-by-layer paths.

[0059] S14. Add two virtual extruders in the slicing software: a first extruder and a second extruder, wherein the first extruder is set to have a small-diameter nozzle, and the second extruder is set to have a large-diameter nozzle.

[0060] S15. In the slicing software, it is set that the outer wall is printed using the first extruder, and the filling is printed using the second extruder.

[0061] S16. In the print control code, the instruction for switching the extruder is replaced with an instruction for controlling the drive mechanism, so that the nozzle diameter is switched when the extruder is switched. It can be understood that in step S16, the instruction for controlling the drive mechanism is the instruction for controlling the servo 7 of the drive mechanism. By controlling the servo 7 to drive the moving coil 4 to rotate forward or reverse, the diameter of the channel 12 is changed, that is, the diameter of the nozzle is changed. The nozzle diameter corresponding to the second extruder is larger than the nozzle diameter corresponding to the first extruder.

[0062] Preferably, the present invention is applicable to the application of variable diameter nozzles manufactured by melt extrusion and further includes: the above-mentioned instructions for controlling the driving mechanism control the rotation angle of the dynamic coil 4 by controlling the rotation angle of the servo 7, thereby achieving precise change in the positions of the multiple closed teeth 5 and changing the diameter of the channel 12; the above-mentioned instructions for controlling the driving mechanism are sent to the servo 7 of the driving mechanism through the control system; in addition, preferably, the above-mentioned control system can also integrate a feedback mechanism, and a position sensor is installed on the closed tooth 5 or the driving mechanism, and the actual diameter of the channel 12 is monitored in real time by the above-mentioned position sensor, and compared with the nozzle diameter setting value, thereby realizing closed-loop control to improve the accuracy and reliability of the nozzle diameter adjustment, wherein the above-mentioned position sensor can be an encoder, a potentiometer or a laser diameter gauge, etc.

[0063] S17. In order to achieve good effects of small-diameter nozzle extrusion (i.e., corresponding to the above-mentioned first extruder) and large-diameter nozzle extrusion (i.e., corresponding to the above-mentioned second extruder), temperature control instructions and speed control instructions are added to the printing control code to control the printing temperature and printing speed of the first extruder and the second extruder, wherein the printing temperature of the second extruder is higher than the printing temperature of the first extruder, and the printing speed of the first extruder is greater than the printing speed of the second extruder; that is, the large-diameter nozzle of the second extruder requires a higher extrusion volume, so the printing temperature of the second extruder needs to be increased and its printing speed needs to be reduced; while the small-diameter nozzle of the first extruder reduces its printing temperature and increases its printing speed.

[0064] S18: Generate the final printing control code, calibrate the printing platform, start the printing task and monitor it.

[0065] It can be understood that through the above steps S11-S18, the variable diameter nozzle of the present invention is used to perform melt extrusion additive manufacturing to achieve variable diameter extrusion. During the printing process, combined with the slicing software settings, a small layer height and small diameter nozzle (i.e. corresponding to the above-mentioned first extruder) is used to print the outer wall, and a large layer height and large diameter nozzle (i.e. corresponding to the above-mentioned second extruder) is used for internal filling to achieve high-quality surface and efficient molding, thereby improving printing efficiency. Through the adjustment of the variable diameter nozzle of the present invention, the extrusion amount of the molten material can be reasonably controlled according to printing requirements, thereby avoiding material waste and improving material utilization.

[0066] In addition, preferably, in another embodiment, the present invention combines a variable diameter nozzle and a slicing software setting to solve the casting problem in the printing process. Specifically, the present invention is applicable to the application of a variable diameter nozzle for melt extrusion manufacturing, specifically comprising the following steps S21-S24:

[0067] S21. Import the model file into the slicing software, and the slicing software recognizes the model features.

[0068] S22. Slice the model in layers.

[0069] S23, identifying the paths that require retraction and backfilling during the printing process, adding a nozzle closing action to the retraction path; and adding a nozzle opening action to the backfill path.

[0070] S24, add nozzle closing and nozzle opening control codes after the backfill and backfill codes in the printer control code; it can be understood that nozzle closing corresponds to closing the channel formed by the closing teeth, and nozzle opening corresponds to opening the channel, and the nozzle closing and nozzle opening control codes correspond to the control codes for controlling the driving mechanism servo 7. In this step S24, if Figure 10 、 Figure 11The figures show two states of the variable diameter nozzle of the present invention. The nozzle diameter can be switched arbitrarily between the closed and open states by the rotation and control of the driving mechanism servo, so as to effectively solve the casting problem and reduce the wire drawing problem in the printing process.

[0071] It can be understood that the present invention sets the above-mentioned steps S21-S24, by identifying the paths that need to be withdrawn and backfilled during the printing process in the slicing software, and adding control codes for closing the nozzle and opening the nozzle respectively. Combined with the use of the variable diameter nozzle of the present invention, the nozzle is automatically closed in the withdrawn path (i.e., channel 12 is closed), and the nozzle is automatically opened in the backfill path (i.e., channel 12 is opened). That is, the variable diameter nozzle of the present invention acts as a valve to disconnect the extrusion channel, which effectively solves the problem of melt casting during the printing process, thereby improving material utilization and improving the quality and surface finish of the printed model.

[0072] In addition, preferably, the application of a variable diameter nozzle suitable for melt extrusion manufacturing of the present invention may also include: according to the stress conditions and structural characteristics of the model, an adaptive filling algorithm is used, and a higher filling density is used in the key stress-bearing parts of the model to ensure the strength of the parts; while in non-stress-bearing parts or unimportant areas, a lower filling density or a special filling pattern, such as honeycomb, grid, etc. is used; through the above method, it is possible to reduce the amount of material used without affecting the performance of the parts.

[0073] Compared with the prior art, the present invention provides a variable diameter nozzle suitable for melt extrusion manufacturing and its application, which has the following beneficial effects: (1) The present invention includes a driving mechanism and a variable diameter nozzle structure, wherein the variable diameter nozzle structure includes a moving coil, a fixed coil and a plurality of closed teeth. The driving mechanism can drive the moving coil to rotate to change the position of the plurality of closed teeth, thereby changing the diameter of the channel for the molten material to pass through. The moving coil is linked by a servo and a driving gear to accurately control the closed teeth to form a variable flow channel. Through the above-mentioned method, the present invention can achieve infinite adjustment of the nozzle diameter of 0-5mm by only using the variable diameter nozzle of the present invention without switching the print head. The nozzle diameter can be flexibly adjusted according to the printing requirements, thereby improving the printing accuracy and quality, effectively solving the problem of fixed nozzle diameter in the prior art, achieving a breakthrough in variable diameter nozzle technology, and better adapting to meet the needs of different scenarios from fine surface to fast filling. (2) The first feed port of the fixed coil is connected to the nozzle of the additive manufacturing device in the form of a threaded connection, which improves the versatility of the variable diameter nozzle of the present invention, making the present invention applicable to multiple types of additive manufacturing devices and compatible with mainstream FDM / FGF printers on the market. (3) The closed teeth of the present invention adopt a double-conical design: the conical funnel-shaped second feed port of the closed teeth can prevent the generation of air holes, and the conical funnel-shaped second discharge port of the closed teeth can better avoid the collision between the variable diameter nozzle and the printed part model. (4) The variable diameter nozzle of the present invention is combined with the intelligent control of the slicing software. The outer wall is printed with a small diameter nozzle with high precision, and the internal filling is switched to a large diameter nozzle for high-speed molding, which improves the surface quality while also improving efficiency; the innovative integrated nozzle opening and closing control code automatically closes the flow channel or channel in the retraction path, effectively solving the problem of melt casting and improving material utilization. In this way, the variable diameter nozzle of the present invention achieves the coordinated optimization of printing accuracy, efficiency and material economy, and provides an innovative solution for melt extrusion manufacturing.

[0074] It should be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not preclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0075] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A variable diameter nozzle suitable for melt extrusion manufacturing, characterized in that include: A driving mechanism and a variable diameter nozzle structure, wherein the variable diameter nozzle structure includes a moving coil, a fixed coil and a plurality of closed teeth, the driving mechanism is connected to the moving coil, the fixed coil and the moving coil are coaxial, each of the closed teeth is connected to the moving coil and the fixed coil, the plurality of closed teeth are distributed in a circle and form a channel for the molten material to pass through, the upper and lower ends of the fixed coil are respectively provided with a first feed port and a first discharge port, the first discharge port is arranged correspondingly to the channel above and below, and the driving mechanism is used to drive the moving coil to rotate to change the position of the plurality of closed teeth and change the diameter of the channel.

2. The variable diameter nozzle suitable for melt extrusion manufacturing according to claim 1, characterized in that: The moving coil is provided with a first screw and the fixed coil is provided with a second screw, the closing tooth is connected to the moving coil via the first screw, and the closing tooth is connected to the fixed coil via the second screw; the moving coil is provided with a plurality of first sliding grooves, and the fixed coil is provided with a plurality of second sliding grooves, the plurality of first sliding grooves and the plurality of second sliding grooves are all distributed circumferentially, and the number of the first sliding grooves and the number of the second sliding grooves are the same as the number of the closing teeth.

3. The variable diameter nozzle suitable for melt extrusion manufacturing according to claim 2, characterized in that: A square boss is provided at the upper rear end of the closing tooth, the first screw is connected to the square boss, the first slide groove is a square slide groove, the square boss is located in the first slide groove, and the closing tooth moves in the first slide groove through the square boss.

4. The variable diameter nozzle suitable for melt extrusion manufacturing according to claim 3, characterized in that: The upper part of the closing tooth is connected to the second screw near the front end. The second slide groove is an arc slide groove. A cylinder is provided in the middle of the second screw. The cylinder is located in the second slide groove. The closing tooth moves in the second slide groove through the cylinder.

5. The variable diameter nozzle suitable for melt extrusion manufacturing according to claim 1, characterized in that: The upper front ends of the plurality of closed teeth form a concave second feed opening, the second feed opening is arranged corresponding to the upper end of the channel, and the second feed opening is in the shape of a conical funnel.

6. The variable diameter nozzle suitable for melt extrusion manufacturing according to claim 5, characterized in that: The front ends of the lower parts of the plurality of closed teeth form a downwardly convex second discharge port, the second discharge port is arranged corresponding to the lower end of the channel, and the second discharge port is in a conical funnel shape.

7. The variable diameter nozzle suitable for melt extrusion manufacturing according to claim 1, characterized in that: The first feed port is connected to the nozzle of the additive manufacturing device in a threaded connection form.

8. The variable diameter nozzle suitable for melt extrusion manufacturing according to claim 1, characterized in that: The driving mechanism includes a steering gear, a driving gear and a driving plate. The moving coil is connected to the driving plate via a third screw. The driving gear is connected to the steering gear via a fourth screw. The driving gear is meshed with the driving plate.

9. An application of a variable diameter nozzle suitable for melt extrusion manufacturing, characterized in that: The variable diameter nozzle suitable for melt extrusion manufacturing according to any one of claims 1 to 8 is applied to melt extrusion additive manufacturing.

10. The use of the variable diameter nozzle suitable for melt extrusion manufacturing according to claim 9, characterized in that: The following steps are involved: S11, import the model file to be printed into the slicing software and perform model preprocessing; S12, the slicing software identifies features of the model; S13, the slicing software slices the model in layers, sets layer height and support, and generates a layer-by-layer path; S14. Add two virtual extruders in the slicing software: a first extruder and a second extruder, wherein the first extruder is configured to have a small-diameter nozzle and the second extruder is configured to have a large-diameter nozzle; S15, setting in the slicing software that the outer wall is printed using the first extruder and the filling is printed using the second extruder; S16. Replacing the instruction for switching the extruder with the instruction for controlling the driving mechanism in the printing control code, so that the nozzle diameter is switched when the step of switching the extruder is performed; S17. Adding a temperature control instruction and a speed control instruction to the print control code to control the printing temperature and the printing speed of the first extruder and the second extruder, wherein the printing temperature of the second extruder is higher than the printing temperature of the first extruder, and the printing speed of the first extruder is higher than the printing speed of the second extruder; S18: Generate the final printing control code, calibrate the printing platform, start the printing task and monitor it.

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