Dual-mode FDM three-dimensional printing device capable of switching high-speed mode and high-precision mode and printing method of dual-mode FDM three-dimensional printing device

Abstract

The invention provides a dual-mode FDM three-dimensional printing device capable of switching a high-speed mode and a high-precision mode and a printing method of the dual-mode FDM three-dimensional printing device, and relates to the technical field of three-dimensional printing. The dual-mode FDM three-dimensional printing device comprises a first printing head, a second printing head, a switching mechanism, a control module and a material breaking control module; the opening diameter of the outlet is configured to be matched with the diameter of a supplied wire rod so as to carry out semi-molten deposition; the second printing head is provided with a contraction nozzle and is used for carrying out molten-state high-precision printing; the switching mechanism is used for selectively moving the first printing head or the second printing head to a working position; large-flow and semi-molten-state rapid accumulation of materials is achieved through the high-speed printing head-first printing head without a nozzle, the printing speed is improved compared with a traditional high-precision mode, it is ensured that a model finally obtains excellent surface quality and detail expression through the switchable standard high-precision printing head-second printing head, and rapid inside and precise outside are achieved.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and in particular to a dual-mode FDM 3D printing device and printing method that can switch between high-speed and high-precision modes. Background Technology

[0002] Fused deposition modeling (FDM) 3D printing technology uses thermoplastic filaments as raw materials, which are heated and melted through a nozzle and then deposited layer by layer to form the final product. To improve printing efficiency, existing technologies often employ methods such as increasing the nozzle orifice diameter, extending the heating zone, or using screw extrusion to achieve higher material flow rates. However, existing solutions have the following shortcomings: First, extrusion methods that force complete material melting are energy-intensive and have complex temperature control; second, it is difficult to quickly and conveniently switch printing modes on the same device according to different printing needs; third, special structures such as screw extrusion often lead to high device costs and increased size, and are difficult to be compatible with conventional gear-feed printheads. In addition, mechanical cutters or shearing devices designed to control the material have complex structures and are not suitable for cutting off ordinary thermoplastic filaments, easily producing filament dragging or residual flow; therefore, this invention proposes a dual-mode FDM 3D printing device and its printing method that can switch between high-speed and high-precision modes to solve the problems existing in the prior art. Summary of the Invention

[0003] To address the aforementioned issues, this invention proposes a dual-mode FDM 3D printing device and method that can switch between high-speed and high-precision modes. The high-speed print head without nozzles—the first print head—achieves rapid material deposition in a high flow rate and semi-molten state, increasing the printing speed compared to the traditional high-precision mode. The switchable standard high-precision print head—the second print head—ensures that the final model achieves excellent surface quality and detail, realizing an intelligent printing strategy of fast internal and precise external printing.

[0004] To achieve the objectives of this invention, the invention is implemented through the following technical solution: a dual-mode FDM 3D printing device capable of switching between high-speed and high-precision modes, comprising a first print head, a second print head, a switching mechanism, a control module, and a feed-cut-off control module. The first print head has a heating chamber and an outlet, and the opening diameter of the outlet is configured to adapt to the diameter of the supplied filament for semi-molten deposition. The second print head has a shrinking nozzle for performing molten high-precision printing. The switching mechanism is used to selectively move either the first print head or the second print head to a working position. The control module is used to control the printing mode, temperature, and feeding; the material cut-off control module is used to achieve non-mechanical material discharge termination when the first print head finishes working by controlling its temperature to drop, reversing the feeding, and applying cooling.

[0005] A further improvement is that the length of the heating chamber of the first printhead is 20 to 50 times the diameter of the wire it uses.

[0006] A further improvement is that it also includes a cold air nozzle located at the outlet of the first printhead, and the control module controls the cold air nozzle to spray and cool the end of the material within 0.2 to 1.0 seconds.

[0007] A further improvement is that the switching mechanism is one of a translational slide, a rotary structure, or a coaxial valve structure.

[0008] A further improvement is that the control module stores two independent sets of control parameters corresponding to the high-speed printing mode of the first printhead and the high-precision printing mode of the second printhead, respectively.

[0009] A further improvement is that the outlet diameter of the first printhead is in the range of 1.5 to 3.0 mm, and the nozzle diameter of the second printhead is in the range of 0.2 to 0.6 mm.

[0010] A dual-mode FDM 3D printing method with switchable high-speed and high-precision modes includes the following steps: S1: Divide the 3D model into a high-speed printing area and a high-precision printing area; S2: In the high-speed printing area, material is deposited in a semi-molten state using the first printhead; S3: When it is necessary to switch to the high-precision printing area, perform material cut-off operations on the first print head, including cooling, feeding reversal and cooling. S4: Switch to the second printhead for fine molten printing in the high-precision printing area.

[0011] A further improvement is that in S3, the material cutting operation is performed in the following order: first, the temperature of the heating chamber of the first print head is reduced by 10-25°C, then the feed is reversed and the wire is retracted by 2-6mm, and at the same time, jet cooling is applied to cool the material at the outlet for 0.3-1.0 seconds.

[0012] A further improvement is that the material cutting operation causes the material to form a solidified seal or natural break point at the exit of the first printhead, and the seal or break point is restored to continuity when the first printhead is heated back to the operating temperature.

[0013] A further improvement is that, in S1, the layer thickness of the high-speed printing area is 1.0 to 3.0 mm, and the layer thickness of the high-precision printing area is 0.1 to 0.3 mm.

[0014] The beneficial effects of this invention are as follows: 1. This invention achieves high flow rate and rapid semi-molten material deposition through a nozzle-free high-speed printhead - the first printhead, which improves the printing speed compared to the traditional high-precision mode. Through a switchable standard high-precision printhead - the second printhead, it ensures that the model finally obtains excellent surface quality and detail, realizing an intelligent printing strategy of fast inside and precise outside.

[0015] 2. This invention adopts a non-mechanical material cutting method of temperature control retreat + cooling and sealing. Through the synergistic effect of temperature reduction and thickening, reverse extraction and pressure relief and instant cold air curing, the discharge of semi-molten wire can be quickly terminated within 0.5 to 1.0 seconds, effectively eliminating wire dragging and residual flow. Moreover, it does not require a complicated mechanical cutting device, reducing costs and failure rate.

[0016] 3. The dual printhead switching mechanism of this invention is simple and easy to implement, with a compact overall structure and controllable cost. The high-speed printhead has low requirements for complete material melting, resulting in a significant reduction in energy consumption. It has good applicability to a variety of commonly used thermoplastic materials such as PLA, ABS, PETG, and PP. Moreover, the entire printing and switching process can be fully automated by the control program, resulting in higher efficiency. Attached Figure Description

[0017] Figure 1 This is the front view of the present invention; Figure 2 This is a flowchart of the present invention. Detailed Implementation

[0018] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0019] Example 1 according to Figure 1 , 2As shown, this embodiment proposes a dual-mode FDM 3D printing device with switchable high-speed and high-precision modes, including a first print head, a second print head, a switching mechanism, a control module, and a material cut-off control module. The first print head has a heating chamber and an outlet, and the opening diameter of the outlet is configured to adapt to the diameter of the supplied filament for semi-molten deposition. The second print head has a shrink nozzle for high-precision molten printing. The switching mechanism is used to selectively move either the first or second print head to the working position. The shrink nozzle of the traditional high-speed print head is eliminated, allowing material to be extruded at a size close to the original diameter. This directly and significantly increases the material deposition rate per unit time, resulting in an order-of-magnitude increase in the filling efficiency of large-volume parts. At the same time, semi-molten deposition reduces the energy consumption required for complete material melting. The high-precision print head is dedicated to forming complex contours, fine features, and high-quality surfaces. Its small-aperture nozzle ensures that the extruded lines are delicate and precise, which is key to achieving the final part's dimensional accuracy and surface finish. This allows a single device to simultaneously meet the dual needs of rapid manufacturing of structural parts and precision forming of appearance parts. It achieves rapid and accurate switching between the two printing modes at the physical execution end. Users or control programs can flexibly call the most suitable printhead according to the needs of the model area without interrupting the operation or replacing hardware, which greatly enhances the process adaptability and task processing capability of a single device. The control module controls the printing mode, temperature, and material feeding. The material cut-off control module, when the first printhead finishes its work, controls its temperature to drop, reverses the material feeding, and applies cooling to achieve non-mechanical material discharge termination. Integrated intelligent control is the brain of the device's automatic operation. The innovation of the material cut-off control module is particularly crucial; through the synergy of thermal management and motion control, it cleanly and efficiently cuts off the semi-molten material flow using purely electronic control. This completely avoids the jamming, wear, or compatibility issues that may arise with mechanical cutters, significantly improving the system's reliability and ease of maintenance.

[0020] The heating chamber of the first printhead is 20 to 50 times the diameter of the filament used. The extended heating chamber provides a sufficient gradient heating area for the filament, which is the physical basis for achieving a stable "semi-molten state". This structure ensures that the outer layer of the filament is sufficiently softened to guarantee adhesion, while the inner core maintains a certain rigidity to support stable extrusion, effectively preventing drooling or shape loss problems caused by excessive melting of the material.

[0021] It also includes a cold air nozzle located at the exit position of the first printhead. The control module controls this cold air nozzle to spray and cool the material tip within 0.2 to 1.0 seconds. The cold air nozzle is the direct actuator of the "cooling and sealing" action, and its instantaneous and powerful cooling capability is crucial. It can reduce the surface temperature of the semi-molten material below the glass transition temperature within milliseconds, achieving rapid solidification. Working in conjunction with the temperature control retreat step, it ensures that the material cutting process is fast and thorough, with a clean break and no dragging or fraying.

[0022] The switching mechanism is one of a translational slide, a rotary structure, or a coaxial valve structure. Multiple specific implementation methods of the switching mechanism are provided, giving the device design flexibility. Translational and rotary structures are simple and reliable, and easy to integrate into existing platforms; the coaxial valve structure is more compact, capable of millisecond-level flow channel switching, meeting the development needs of different models and products with different performance positioning.

[0023] The control module stores two independent sets of control parameters corresponding to the high-speed printing mode of the first printhead and the high-precision printing mode of the second printhead, respectively. Pre-storing and quickly recalling these two independent sets of parameters, such as temperature, speed, and flow rate, is a prerequisite for achieving "one-click switching" or "automatic switching" functionality. This simplifies user operation and the complexity of slicing software configuration, ensuring that both modes operate within their respective optimal process windows, thereby achieving the best printing results.

[0024] The exit diameter of the first printhead ranges from 1.5 to 3.0 mm, while the nozzle diameter of the second printhead ranges from 0.2 to 0.6 mm. Defining the key size ranges of the two printheads establishes a quantitative basis for performance comparison. A large exit diameter (1.5-3.0 mm) is necessary for achieving high-speed deposition, while a small nozzle diameter (0.2-0.6 mm) is a common choice for achieving high precision. The combination of these two clearly defines the performance boundaries of the "dual-mode" system at the hardware level.

[0025] A dual-mode FDM 3D printing method with switchable high-speed and high-precision modes includes the following steps: S1: The 3D model is divided into a high-speed printing area and a high-precision printing area. The layer thickness of the high-speed printing area is 1.0–3.0 mm, and the layer thickness of the high-precision printing area is 0.1–0.3 mm. This begins with an intelligent model partitioning strategy, which is the logical starting point for leveraging the advantages of the dual-mode approach. Through software algorithms or manual settings, solid fills, supporting structures, and other parts of the model that do not require high precision are assigned to the high-speed area and printed with a large layer thickness (1.0–3.0 mm); while outer walls, fine features, etc., are assigned to the high-precision area and printed with a small layer thickness (0.1–0.3 mm). This maximizes the optimization of overall printing time and material distribution from the planning stage. S2: In the high-speed printing area, the first print head is used to deposit material in a semi-molten state; the core execution stage that improves efficiency: the first print head runs at a speed much higher than usual, and uses large-diameter semi-molten extrusion to quickly complete the construction of the main body of the model, greatly compressing the filling process that was originally the most time-consuming, saving considerable time costs for the entire printing task. S3: When switching to a high-precision printing area, a material cut-off operation is performed on the first printhead, including cooling, feed reversal, and heat dissipation. The material cut-off operation is performed in the following sequence: first, the heating chamber temperature of the first printhead is reduced by 10–25°C; then, the feed is reversed to retract the filament by 2–6 mm, while simultaneously applying jet cooling to cool the material at the exit for 0.3–1.0 seconds. The material cut-off operation causes the material to form a solidified seal or natural break point at the exit of the first printhead. This seal or break point is restored when the first printhead is reheated to its operating temperature. A standardized and reusable material cut-off process is defined, achieving clean material cut-off within seconds through a combination of cooling and thickening, reverse extraction and pressure relief, and instantaneous cooling and solidification. This not only prevents dripping and stringing during the switching process, but the resulting "reversible" seal also ensures that the high-speed printhead can be immediately reactivated when needed, guaranteeing the continuity and reliability of the process.

[0026] S4: Switch to the second printhead for fine molten printing in the high-precision printing area. The final stage ensuring part quality: After the high-speed skeleton is completed, the high-precision printhead takes over, meticulously constructing the model's surface and key dimensional features using a fine path and a fully molten material state. The final product thus possesses both the high efficiency of internal manufacturing and the high quality of external forming, achieving a comprehensive performance that is difficult to achieve with a single traditional printing strategy.

[0027] Example 2 according to Figure 1 , 2 As shown, this embodiment proposes a dual-mode FDM 3D printing device and method that can switch between high-speed and high-precision modes, including a translational dual-printhead system: The printer body has two independent printheads: the left one is a high-speed printhead with an exit diameter of 1.75mm (compatible with 1.75mm filament) and a heating chamber length of 50mm; the right one is a high-precision printhead equipped with a 0.4mm orifice nozzle. Both are mounted on the same horizontal slide and switched by a stepper motor.

[0028] When printing a model with a solid interior and a complex exterior, the slicing software automatically divides the model into sections. First, the slide moves to position the high-speed printhead, which rapidly fills the interior area in a semi-molten state at 210°C. After filling, the control system executes a material-cut macro command: the feed motor reverses by 5mm, the heating temperature drops to 190°C, and simultaneously, a miniature fan located on the side of the high-speed printhead exit starts blowing cool air for 0.5 seconds. The material tip is observed to solidify rapidly, forming a smooth spherical end cap. Subsequently, the slide moves to switch to a high-precision printhead, which, after preheating, continues to print the outer surface of the model at 200°C with a layer height of 0.2mm. The entire process is stringless, and the transitions are seamless.

[0029] Example 3 according to Figure 1 , 2 As shown, this embodiment proposes a dual-mode FDM 3D printing device and its printing method that can switch between high-speed and high-precision modes, including a coaxial valve type printhead: It adopts a coaxial compact design with a single feed channel and dual discharge paths. The filament pushed by the feeding mechanism enters a diverter controlled by an electric valve core. When the valve core points to the large-diameter channel (without nozzles), high-speed printing is performed; when the valve core rotates at a certain angle, guiding the material to the small-diameter nozzle (0.6mm) on the side branch, high-precision printing is performed. The material cut-off control principle is the same as in Example 2. Before the valve core switches, cooling, back-pulling, and cold air curing operations are performed on the currently working flow channel.

[0030] Example 4 according to Figure 1 , 2 As shown, this embodiment proposes a dual-mode FDM 3D printing device and its printing method that can switch between high-speed and high-precision modes, including intelligent partitioned printing control: The slicing software integrates AI algorithms based on curvature analysis and volume calculation. The algorithm automatically identifies large planes, internal filled areas (recommended for high-speed printing), high-curvature surfaces, micro-holes, and overhanging structures (recommended for high-precision printing) in the model. The software generates a composite G-code file containing mode switching instructions, material cut-off macro calls, and corresponding printhead temperature / speed parameters, achieving a fully automated "segmentation-printing-switching" process.

[0031] Example 5 according to Figure 1 , 2 As shown, this embodiment proposes a dual-mode FDM 3D printing device and its printing method that can switch between high-speed and high-precision modes, including tests on the suitability of different materials. The tests were conducted using two materials with different properties: PLA and PP.

[0032] For PLA material, after high-speed printing, a 15°C cooling process (from 210°C to 195°C), a 3mm reverse pull, and a 0.5-second cold air cycle are performed, resulting in complete material breakage at the exit without any stringing.

[0033] For PP materials with higher crystallinity and shrinkage, more significant material breaking parameters were used: a 25°C temperature drop (from 230°C to 205°C), a 5mm back-pull, and a 1-second cold air cycle. It was observed that the material not only broke off at the end but also formed a tiny, solidified "plug" on the inner wall of the outlet, effectively preventing the slow seepage of residual material from the cavity. When the printhead was restarted, the "plug" remelted as the temperature rose, without affecting subsequent continuous printing.

[0034] Example 6 according to Figure 1 , 2 As shown, this embodiment proposes a dual-mode FDM 3D printing device and its printing method that can switch between high-speed and high-precision modes, including a material breakage control mechanism: Thermodynamic and fluid dynamic simulations revealed that when the heating chamber temperature drops to near the material's softening point (±3°C), the melt viscosity of the outer layer of the semi-fused wire increases dramatically by 2-3 orders of magnitude, resulting in a sharp decrease in fluidity. At this point, the reverse reversal of the feed motor creates a tensile stress concentration point within the material. Simultaneously applied instantaneous strong cooling airflow cools the outer layer of the material at the outlet to below its glass transition temperature within 0.8 seconds, causing solidification shrinkage. The synergistic effect of the dramatic increase in viscosity, tensile stress, and solidification shrinkage leads to the formation of a necking point near the outlet, ultimately resulting in clean fracture or the formation of a sealed solidification cap, thus achieving reliable material cutting without mechanical intervention.

[0035] This invention utilizes a nozzle-free high-speed printhead—the first printhead—to achieve high-flow, semi-molten material deposition, resulting in a higher printing rate than traditional high-precision methods. A switchable standard high-precision printhead—the second printhead—ensures excellent surface quality and detail in the final model, achieving a smart printing strategy of high speed internally and high precision externally. Furthermore, this invention employs a non-mechanical material-cutting method combining temperature-controlled retraction and cooling sealing. Through the synergistic effects of cooling and thickening, reverse pressure release, and instantaneous cold air curing, it can rapidly terminate the ejection of semi-molten filament within 0.5 to 1.0 seconds, effectively eliminating filament dragging and residual flow. It also eliminates the need for complex mechanical cutting devices, reducing costs and failure rates. Simultaneously, the dual printhead switching mechanism of this invention is simple to implement, with a compact overall structure and controllable costs. The high-speed printhead has low requirements for complete material melting, significantly reducing energy consumption. It has good applicability to various commonly used thermoplastic materials such as PLA, ABS, PETG, and PP. Moreover, the entire printing and switching process can be fully automated by the control program, resulting in higher efficiency.

[0036] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dual-mode FDM 3D printing device capable of switching between high-speed and high-precision modes, comprising a first print head, a second print head, a switching mechanism, a control module, and a material cut-off control module, characterized in that: The first printhead has a heating chamber and an outlet, and the opening diameter of the outlet is configured to adapt to the diameter of the supplied filament for semi-molten deposition; the second printhead has a shrink nozzle for high-precision molten printing; the switching mechanism is used to selectively move the first printhead or the second printhead to a working position. The control module is used to control the printing mode, temperature, and feeding; the material cut-off control module is used to achieve non-mechanical material discharge termination when the first print head finishes working by controlling its temperature to drop, reversing the feeding, and applying cooling.

2. The dual-mode FDM 3D printing device with switchable high-speed and high-precision modes according to claim 1, characterized in that: The length of the heating chamber of the first printhead is 20 to 50 times the diameter of the wire it uses.

3. The dual-mode FDM 3D printing device with switchable high-speed and high-precision modes according to claim 1, characterized in that: It also includes a cold air nozzle located at the outlet of the first printhead, and the control module controls the cold air nozzle to spray and cool the end of the material within 0.2 to 1.0 seconds.

4. The dual-mode FDM 3D printing device with switchable high-speed and high-precision modes according to claim 1, characterized in that: The switching mechanism is one of the following: a translational slide, a rotary structure, or a coaxial valve structure.

5. The dual-mode FDM 3D printing device with switchable high-speed and high-precision modes according to claim 1, characterized in that: The control module stores two sets of independent control parameters corresponding to the high-speed printing mode of the first printhead and the high-precision printing mode of the second printhead, respectively.

6. The dual-mode FDM 3D printing device with switchable high-speed and high-precision modes according to claim 1, characterized in that: The outlet diameter of the first printhead ranges from 1.5 to 3.0 mm, and the nozzle diameter of the second printhead ranges from 0.2 to 0.6 mm.

7. A dual-mode FDM 3D printing method with switchable high-speed and high-precision modes, employing the dual-mode FDM 3D printing apparatus with switchable high-speed and high-precision modes as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Divide the 3D model into a high-speed printing area and a high-precision printing area; S2: In the high-speed printing area, the first printhead is used to deposit material in a semi-molten state; S3: When it is necessary to switch to the high-precision printing area, perform material cut-off operations on the first print head, including cooling, feeding reversal and cooling. S4: Switch to the second printhead for fine molten printing in the high-precision printing area.

8. The dual-mode FDM 3D printing method with switchable high-speed and high-precision modes according to claim 7, characterized in that: In S3, the material cutting operation is performed in the following order: first, the temperature of the heating chamber of the first print head is reduced by 10-25°C, then the feed is reversed and the wire is retracted by 2-6mm, and at the same time, jet cooling is applied to cool the material at the exit for 0.3-1.0 seconds.

9. A dual-mode FDM 3D printing method with switchable high-speed and high-precision modes according to claim 8, characterized in that: The material cut-off operation causes the material to form a solidified seal or natural break point at the exit of the first printhead, which is restored to continuity when the first printhead is reheated to the operating temperature.

10. A dual-mode FDM 3D printing method with switchable high-speed and high-precision modes according to claim 7, characterized in that: In S1, the layer thickness of the high-speed printing area is 1.0 to 3.0 mm, and the layer thickness of the high-precision printing area is 0.1 to 0.3 mm.

Images