Three-dimensional printing head hot end with integrated heat shield and manufacturing process

Abstract

Three-dimensional printing head hot end with integrated heat shield and manufacturing process, belong to mechanical structure field, especially suitable for FDM-3D printer, the three-dimensional printing head hot end is double-layer structure: namely divided into heat insulation outer layer and inner hot entity structure; The heat insulation outer layer covers the surface of the inner hot entity, and the fixed connection with the inner hot entity is connected through columnar or strip connection structure, the hot end is manufactured by 3D printing manufacturing process, suitable metal 3d printing process includes SLS, 3DP, SLM, FDM technology, the 3D model of the hot end needs to be modeled in the three-dimensional modeling software on the computer and converted into STL format, open the STL file in the slicing software to complete the slicing file of the 3d printing of the hot end; Then by 3d printer layer by layer to complete the manufacture of hot end; To complete the integrated production of hot end, widely used in FDM-3D printer field.

Description

Technical Field

[0001] This invention belongs to the field of mechanical manufacturing. More precisely, it is an extruder specifically designed for FDM-3D printers and is suitable for multi-color or mixed-color applications. Background Technology

[0002] This invention is an improvement on the hot end of the print head in FDM-3D printing technology.

[0003] FDM (Fused Deposition Modeling) 3D printing technology is a rapid prototyping process that involves heating and melting various filaments to deposit them layer by layer to form a 3D model. FDM can utilize a wide range of materials, including modified paraffin wax, nylon, rubber, and other thermoplastics, as well as multiphase mixtures such as metal powders, ceramic powders, and short fibers combined with thermoplastics. PLA (polylactic acid) is particularly advantageous due to its low shrinkage rate, easier shaping of printed models, and biodegradability.

[0004] The basic structure and operating principle of the FDM-3D printer are described as follows: The main components include a feeding mechanism, a mechanical platform that carries the extruder in 2D or 3D (horizontal X-axis and Y-axis movement and vertical Z-axis drive), or a platform where the extruder remains stationary in the vertical direction (Z-axis direction), with movement in the Z-axis direction accomplished by the lifting and lowering of an independent worktable. Currently, the 3D mechanical systems driving the extruder for addressing in FDM-3D printers are categorized as follows: a robotic arm 3D displacement system, a belt- or screw-driven (X, Y-axis) 2D mechanical transmission + (Z-axis) lifting worktable system, and a vertical 3-screw drive (commonly known as the ʓ method) displacement drive system using linkages to connect the extruder platform. There are also structural housings that maintain the aforementioned movements, and electronic control systems that support the mechanical system's motion. The operation is as follows: Under the control of the electronic system, the extruder moves in the XY plane according to the cross-sectional contour information of the product part. The height of the worktable is adjusted. At the start of printing, the worktable plane is located at the nozzle position of the hot melt nozzle. Thermoplastic filament material is fed to the hot melt nozzle by the filament feeding mechanism, heated and melted into a semi-liquid state in the nozzle, and then extruded and selectively coated onto the worktable. After rapid cooling, a thin sheet contour of approximately 0.1-8mm thickness is formed. After one layer of cross-section is formed, the worktable descends a certain height, and the next layer is clad, as if "drawing" the cross-section and contour layer by layer. This cycle continues until a three-dimensional product part is formed. During the printing process, the displacement of the print head on the plane and the up-and-down displacement of the printing platform create a three-dimensional space. The print head and printing platform print according to the generated path. After the print head completes the printing task on one plane, the printing platform automatically descends one layer, and the print head continues printing, repeating the cycle until the finished product is completed.

[0005] Its structural details are as follows: The extruder is the core component of FDM rapid prototyping technology. The extruder's components include the feeder (also called the filament feeder, pusher, etc.) and the extrusion nozzle: throat, heating metal body, heating rod, and temperature sensor, etc. Most extruders use a heating rod to heat the metal block, forcing the plastic filament through the throat's inlet. The filament is then guided through the throat to the heated metal block, where it melts and enters the nozzle area. The molten plastic filament is then extruded from the nozzle under the pressure of the subsequent feed (piston) and onto the printing platform. The throat in the extruder is made of stainless steel to reduce its thermal conductivity. Some stainless steel throats are also lined with Teflon. Because of the continuous heating during printing, the temperature inside the throat rises, causing the material inside to remain molten. When printing stops and cooling occurs, the material adheres to the inside of the throat. When printing resumes, this adhered material cannot melt immediately, causing throat blockage. The Teflon lining prevents the material inside the throat from melting and adhering, greatly improving the blockage problem. Meanwhile, adding a heat sink and fan to the extruder is mainly to reduce the temperature of the upper part of the throat, prevent nozzle blockage, and also to dissipate heat from the extruder. The heated and melted plastic filament is extruded from the nozzle onto the printing table. To reduce defects such as warping and shrinkage caused by sudden temperature drops in the plastic, a heated bed printing table can be used. The nozzles at the bottom of the extruder come in four diameters: 0.2mm, 0.3mm, 0.4mm, and 0.5mm. The 0.4mm nozzle is the most widely used in the market. Of course, nozzles of different diameters can be purchased according to actual needs. It is worth noting that after selecting the nozzle diameter, the corresponding parameters should also be set in the printing software, such as the printing layer height and printing speed in the slicing software, to improve printing quality and accuracy. The gears then press the filament closer together. In a near-end feeding extruder, the feeder is mounted on the extrusion nozzle (often a single component containing a heated aluminum block, heating rod, throat, nozzle, and radiator). The material is directly driven by the feed motor, using the frictional force of the teeth to force the filament into the throat, where it melts in the metal block and is ejected from the nozzle for printing. This mounting method, because the extruder and print head move together, results in a large print head mass and significant inertia during printing, which can easily lead to inaccuracies. Near-end feeding also requires high rigidity in the guide rails. In contrast, far-end feeding mounts the feeder at a position further from the extrusion nozzle, connected by a Teflon guide tube. The drive motor for the far-end feeder is typically mounted on the printer frame, with the filament fed through a guide tube, rather than on the extrusion nozzle. Compared to near-end feeding, far-end feeding requires greater torque to force the material into the print head. The electrical components of the 3D printer play a crucial role in controlling the coordinated, orderly, and complete operation of the entire printing process. Modify some parameters in the firmware as needed to meet printing requirements.

[0006] Other 3D printing technologies for metal forming include SLS (Laser Sintering: a laser beam selectively heats and bonds the current layer of metal powder mixed with binder, followed by sintering of the printed blank), 3DP (Powder Bonding: a printhead selectively sprays adhesive onto the current layer of metal powder, followed by sintering and debinding of the printed blank), SLM (Laser Melting: a laser beam is used to selectively melt the current layer, directly forming a high-density metal print without sintering), and FDM (Fuse Deposition: special metal powder resin filaments are melted and deposited layer by layer using a low-temperature nozzle (200-300 degrees Celsius), followed by sintering and debinding of the printed blank). From the perspective of the forming mechanism of 3D printing, the printing process is a layer-by-layer printing method, similar to ordinary FDM-3D printing technology.

[0007] The software components of all 3D printing technologies are similar. The 3D printer software consists of two main parts: host computer software and slave computer software, each further subdivided. Only through the operation of this software can the main control board set and control the printing parameters. The complete operation process of all software in a 3D printer is as follows: First, the part needs to be modeled in 3D modeling software on a computer. After creating the 3D model, the file is saved as an STL file. The STL file is opened in slicing software (including Slic3r), and through a series of printing settings, slicing is performed to generate code. The code is then opened in another host computer software (including Pronterface) and connected to the motherboard. The slave computer software on the motherboard includes (including) Marlin firmware, etc. Summary of the Invention

[0008] The purpose of this invention is to solve the problem of the installation and manufacturing method of the heat insulation outer layer set on the surface of the hot end (heated metal block), so as to reduce costs and improve the simplicity of assembly, ease of use and maintenance.

[0009] Features of this invention: It uses 3D printing technology, which makes it simple to manufacture, low in cost, and easy to maintain.

[0010] The hot end (also known as the heated metal block) of a 3D printhead with an integrated heat shield is suitable for FDM-3D printers. The structure of an FDM-3D printer printhead includes a heat sink and a hot end. The connection between the heat sink and the hot end is achieved by inserting the two ends of a metal throat into the filament through-hole of the heat sink and the filament inlet of the hot end, respectively. The fit between the metal throat and the insertion hole includes tight fit, threaded fit, bonding, welding, and set screw tightening fit.

[0011] In the case of remote feeding, the feed tube at the top of the print head is usually made of Teflon tubing to pass through the filament; however, in the case of near-end feeding (short-range feeding), the feed inlet at the top of the print head does not need a feed tube and is directly connected to the filament outlet of the feeder (also known as the filament extruder).

[0012] The hot end of this 3D printing head has a double-layer structure: it consists of an outer heat-insulating layer and an inner heat-solid structure. The outer heat-insulating layer covers the surface of the inner heat-solid structure and is fixedly connected to the inner heat-solid structure through columnar or strip-shaped connecting structures. The cross-sectional area of ​​these connecting structures is much smaller than the surface area of ​​the inner heat-solid structure to reduce heat conduction. The outer heat-insulating layer, the inner heat-solid structure, and the connecting structures are all made of the same metal material and are directly integrated into the metal powder 3D printing process.

[0013] Because there is a certain (air) gap between the outer insulating layer and the surface of the inner thermal entity, and because the air in the gap is a poor conductor of heat, the conduction and dissipation of heat from the inner thermal entity to the outside is reduced.

[0014] Other structural details of the hot end include a heating rod, filament inlet, melting chamber, material collection chamber, and nozzle. The nozzle is mounted on the open end face of the material collection chamber and can be connected to the inner heated entity by screws, welding, bonding, or tight fitting; or it can be directly integrated into the molding process using metal powder 3D printing. The heating rod hole is used to accommodate the heating rod component and is installed in the heating rod hole connected to the inner heated entity.

[0015] Manufacturing process of hot end: Hot end can only be manufactured by metal 3D printing process. Suitable metal 3D printing processes include SLS (laser sintering), 3DP (powder bonding), SLM (laser melting), and FDM (fused deposition modeling) technology. The manufacturing process involves creating a 3D model of the hot end (part) using 3D modeling software on a computer and converting it to STL format. The STL file is then opened in slicing software to create the slicing file for 3D printing of the hot end. The 3D printer then executes the slicing file according to the software, manufacturing the hot end layer by layer. However, with an SLM (Laser Melting) 3D printer, the entire process of manufacturing the hot end is completed directly after printing. When using an SLS (Laser Sintering), 3DP (Powder Coating), or FDM (Fused Deposition Modeling) 3D printer to manufacture the hot end, only a preliminary blank is printed. Further processing, such as sintering or debinding, is required to complete the final manufacturing process. SLM is the only exception; sintering or debinding is not required after printing.

[0016] Furthermore: the number of wire inlets at the hot end is 1 to 10; in the case of multiple wire inlets, it is not only applicable to the situation where each independent melting chamber is gathered into a unified collection chamber; it is also applicable to the situation where a special mixing core is inserted between the melting chamber and the collection chamber (mixing core structure: multiple melting inlets on the input surface connect to each melting chamber, and the extension of each melting inlet branches into multiple small melting channels, and these small melting channels pass through multiple melting outlets on the output surface that are spaced apart (crossed), with the output surface facing and adjoining the collection chamber; when the outlets of the small melting channels of each color on the output surface corresponding to each melting inlet are spaced apart, after being gathered in the collection chamber, they are uniformly mixed and sprayed out from the nozzle); or it is also applicable to the situation where a stirring needle is inserted into the collection chamber (a stirring needle is inserted into the collection chamber).

[0017] Furthermore, to suit the characteristics of 3D printing processes, slits or small holes are made at the bends on the surface of the heat-insulating outer layer of the internal heat-insulating entity. The area of ​​the slits and holes accounts for less than 1 / 10 of the total area of ​​the heat-insulating outer layer. This allows for the removal of powder or grease during the manufacturing process at the hot end without significantly reducing the heat insulation. (Powder or grease removal is required for non-selectively cured or sintered slices.)

[0018] Further: To suit the characteristics of 3D printing, during the 3D printing manufacturing process of the hot end, a metal throat can be printed directly on the hot end, or a heat sink can be printed directly on the other end of the metal throat; this eliminates the assembly process between the hot end and the heat sink, simplifying the process and reducing costs.

[0019] The advantages of this invention are: low cost, simple manufacturing, and convenient installation and disassembly for maintenance. Attached Figure Description

[0020] Figure 1 include: Figure 1 A schematic diagram of the structure of a 3D printhead with an integrated heat shield at the hot end.

[0021] Figure 1 B. Exploded view of the 3D printed head with an integrated heat shield at the hot end.

[0022] Figure 2 Schematic diagram of a cross-section of the printhead.

[0023] Figure 3 include: Figure 3 A front view of the hot end structure.

[0024] Figure 3 B. Reverse view of the hot end structure.

[0025] Figure 4include: Figure 4 A schematic diagram of the hot end structure with a mixing core.

[0026] Figure 4 Enlarged schematic diagram of the front and back sides of the B mixing core.

[0027] Attached image captions: 1. Hot end (heated metal block) 1-1 Wire Inlet A 1-2 wire insertion hole B 1-3 Melting Chamber A 1-4 Melting Chamber B 1-5 material collection chambers 1-6 Nozzles 1-7 Heating rod holes 1-8 Thermal Insulation Outer Layer 1-9 Connection Structure 1-10 Sealing rings 1-11 Screw 1 1-12 Internal heating elements 1-13 Process holes 1-14 Material Collection Channel 1-15 Thermal insulation gap 1-16 Spray holes 2 heat sinks 2-1 Heatsink 2-2 Wire Through Hole A 2-3 wire through hole B 2-4 Conical Well Platform 3 trachea 1 4 throats 2 5. Feed tube tableting 6 feed tubes 7 screws 10 strands 11. Partial Section 13 Mixing Core 14 Input Faces 15 Melting Material Inlet 16 Melt Channels 17-channel outlet 18 Output Surface [Specific Implementation Case] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments: like Figure 1 In Figure 1 A and Figure 1 B Figure 2 ; Figure 3 In Figure 3 A and Figure 3 As shown in B: The hot end (heated metal block) (1) is commonly known as the hot end (of the FDM printhead), including filament inlet A (1-1), filament inlet B (1-2), molten material chamber A (1-3), molten material chamber B (1-4), material collection chamber (1-5) and material collection channel (1-14) connecting the molten material chamber and the material collection chamber. The nozzle (1-6) with the spray hole (1-16) in the center and the end face of the material collection chamber can be (optionally) sealed with a sealing ring (1-10). The two can be connected by screw 1 (1-11), or by welding, bonding and tight fit (usually the contact joint of the two needs to be machined with a convex and concave structure that can be plugged into each other) to connect them.

[0028] The heating rod hole (1-7) is used to accommodate the heating rod component. The outer insulating layer (1-8), except for the connection structure (1-9) which occupies a small surface area, is connected to the inner heating element (1-12). Figure 3 As can be seen in the partial illustration of A with the outer insulating layer partially removed, the remaining parts are separated by a certain (air) insulating gap (1-15); since air is a poor conductor of heat, it can reduce the convective dissipation of heat from the inner thermal entity (1-10) to the outside. Figure 3 A partial section (11) of A can expose the internal thermal entity within the partial section.

[0029] The print head is an important component of FDM-3D printing technology (or simply print head). The main structure of the print head is a combination of a heat sink (2) and a hot end (heating metal block) (1). The two are connected by inserting metal throat 1 (3) and metal throat 2 (4) into the filament through holes A (2-2) and B (2-3) of the heat sink (2-1) and into the filament inlet holes A (1-1) and B (1-2) of the hot end (heating metal block) (1). The insertion and fixing relationships include tight fit, threaded fit, bonding, welding fit, etc.

[0030] The feed tube (6) is usually made of Teflon hose, which guides the feed wire (10) into the melting chamber and finally gathers in the material collection channel (1-14); it is ejected from the nozzle (1-16) under external thrust; the feed tube with tapered inner hole is pressed into a plate (5) by screw (7), and the expanded edge of the feed tube (6) is pressed onto the protruding conical well platform (2-4) of the feed wire passage at the upper end of the heat sink.

[0031] Process holes (1-13) with slits and small holes are made at the bending part of the surface of the heat insulation outer layer. These process holes are beneficial for the discharge of powder or grease during the manufacturing process of the hot end.

[0032] like Figure 4 In Figure 4 A, Figure 4 As shown in B: Figure 4 B is an enlarged oblique view of the mixing core (13), with the top view being the front view and the bottom view being the back view.

[0033] The mixing printhead and Figure 2 The structures shown are almost identical, except that a mixing core (13) is installed between each melting chamber and the collecting chamber. The output surface of the mixing core (13) faces downward and is adjacent to the collecting chamber.

[0034] Mixing core (13) structure: The molten material inlet (16) of the input surface (14) connects to each molten material chamber, and enters three small, bent molten material channels along the molten material inlet (16), and finally flows out from the outlets (17) of each color channel on the output surface (18).

[0035] The distribution and positional relationship of the 6 flow channel outlets (17) are as follows: 3 lead to the melt inlet (16), and the other 3 lead to another melt inlet, which are staggered and spaced apart; that is, when using red and green filaments, the discharge colors of the 6 melt outlets on the output surface (18) are red, green, red, green, red, green in clockwise order, so that the two colors are evenly distributed on the output surface and the discharge is evenly mixed.

Claims

1. A 3D printhead hot end with an integrated heat shield, particularly suitable for FDM-3D printers; the 3D printhead hot end structure includes a heating rod hole, a filament inlet hole, a melting chamber, a material collection chamber, and a nozzle, with the nozzle installed on the open end face of the material collection chamber; the heating rod is installed in the heating rod hole connected to the inner heating body; the surface of the hot end has a double-layer structure. That The characteristic is that: The dual-layer structure of the hot end of the 3D printing head is characterized by: a heat-insulating outer layer and an inner heating body, as well as a connection structure connecting the heat-insulating outer layer and the inner heating body; the heat-insulating outer layer covers the surface of the inner heating body, and the fixed connection between the heat-insulating outer layer and the inner heating body is achieved through a columnar or strip-shaped connection structure; both the heat-insulating outer layer and the inner heating body are made of the same metal material.

2. The hot end of the 3D printing head with an integrated heat shield according to claim 1, characterized in that: The number of wire inlets is 1 to 10; in the case of multiple wire inlets, it is applicable not only to the situation where each independent melting chamber is gathered into a unified collection chamber; it is also applicable to the situation where a dedicated mixing core is inserted between the melting chamber and the collection chamber; or it is also applicable to the situation where a stirring needle is inserted into the collection chamber.

3. The hot end of the 3D printing head with an integrated heat shield according to claim 1, characterized in that: The outer heat insulation layer, outside the surface of the inner heat-insulating entity, has slits or small holes at the bends, and the area of ​​the slits and holes accounts for less than 1 / 10 of the total area of ​​the outer heat insulation layer.

4. A manufacturing process for the hot end of a 3D print head with an integrated heat shield: Hot-end components can only be manufactured using 3D printing technology. Suitable metal 3D printing technologies include SLS, 3DP, SLM, and FDM. The manufacturing process involves: creating a 3D model of the hot-end component using 3D modeling software on a computer and converting it to STL format; opening the STL file in slicing software to create the slicing file for the 3D printing of the hot-end component; and then having the 3D printer execute the slicing file according to the slicing software to complete the manufacturing of the hot-end component layer by layer. However, 3D printers using SLM technology can directly complete the manufacturing process of the hot-end component without sintering or debinding after printing. When using SLS, 3DP, SLM, or FDM 3D printers to manufacture the hot-end component, only a preliminary blank is printed. The blank still needs to undergo sintering or debinding processes for further processing before the entire manufacturing process of the hot-end component is finally completed. Its characteristics are: The double-layer structure of the hot end, namely the outer insulating layer and the inner thermal entity and connecting structure, is directly integrated into a model and printed. The printed outer insulating layer of the hot end covers the surface of the inner thermal entity, and the fixed connection between the outer insulating layer and the inner thermal entity is achieved through columnar or strip-shaped connecting structures.

5. A manufacturing process for the hot end of a 3D printing head with an integrated heat shield according to claim 4, characterized in that: In the 3D printing manufacturing process of the hot end, a metal throat can be printed directly on the hot end, or a heat sink can be printed directly on the other end of the metal throat.

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