Flow channel staggered three-dimensional printing double-color mixing nozzle assembly

Abstract

The application discloses a flow channel staggered three-dimensional printing double-color mixing nozzle assembly, and belongs to the mechanical structure field. The basic structure comprises a heating aluminum block, a flow channel cover plate, a nozzle and the like. The flow channel cover plate is processed with a molten material outlet hole leading to each flow channel. Each color material wire pushed by a material pushing device of a printer respectively enters each material wire inlet hole into each molten material cavity, is heated and melted, passes through 2-50 molten material channels arranged respectively, flows into a molten material outlet surface, and then enters each cross-section staggered flow channel. The molten material outlet holes of each color material are staggered and arranged at intervals. The molten material of each color is distributed at intervals. Each color material outlet hole is staggered and arranged at intervals. Then, the molten material flows out from each color staggered outlet of the flow channel cover plate, enters a mixing cavity, and is sprayed out from the nozzle. The application is simple, reliable in operation, and convenient for use in the field of double-color mixing and switching type FDM-3D printers.

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 pertains to FDM-3D printing technology: specifically, Fused Deposition Modeling (FDM). rapid prototyping The process involves combining various filaments (such as...) Engineering plastics ABS Polycarbonate PC Rapid prototyping (FDM) is a method of heating and melting materials and then depositing them layer by layer to form a mold. Most FDM rapid prototyping technologies can use a wide variety of molding materials, such as modified paraffin wax, acrylonitrile / butadiene / styrene copolymer (ABS), nylon, rubber, and other thermoplastic materials, as well as multiphase mixtures, such as mixtures of metal powders, ceramic powders, short fibers, and thermoplastic materials. Among these, PLA (polylactic acid) has advantages such as low shrinkage, easier shaping of printed models, and biodegradability.

[0003] The basic structure and operating principle of the FDM-3D printer are described as follows:

[0004] This mainly includes 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 an extruder that 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 system driving the extruder for addressing in FDM-3D printers is divided into: 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: This includes displacement drive systems that use connecting rods to link the extruder platform, etc.; structural housings that maintain the aforementioned motion; and electronic control systems that support the movement of the mechanical system.

[0005] The process 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. A dedicated nozzle is often used to lay the support material (the support material is generally water-soluble and is washed away with water after printing). 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. Alternatively, instead of using a Z-axis motor to drive the printing platform's lifting and lowering, the printing platform remains stationary along the Z-axis, while the extruder moves up and down using the Z-axis motor. Another option is to use three vertical lead screws to drive three vertically moving sliders, all of which are hinged to the extruder. An algorithm (using the Z-axis coordinates of the three sliders to determine the extruder's 3D spatial position) achieves the same 3D displacement addressing. The printhead temperature is relatively high, varying depending on the material and the model's design temperature. To prevent issues like warping during printing, the printing platform is typically heated and covered with adhesive paper for easy peeling of the printed product.

[0006] Its structural details are as follows:

[0007] 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 prolonged 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 from melting and adhering, greatly improving the blockage problem. The author added heat sinks and fans to the extruder primarily to lower the temperature of the upper part of the throat, preventing nozzle blockage and also to dissipate heat from the extruder. The heated and molten plastic filament is extruded from the nozzle onto the printing table. To reduce defects such as warping and shrinkage caused by sudden temperature drops, a heated bed printing table can be used. The nozzle diameter at the bottom of the extruder commonly comes in four types: 0.2mm, 0.3mm, 0.4mm, and 0.5mm. The 0.4mm nozzle is the most widely used in the market. After selecting the nozzle diameter, corresponding parameters must be set in the printing software, such as the printing layer height and printing speed in slicing software, to improve printing quality and accuracy.

[0008] Compared to a single extruder head, a dual extruder head uses two extruders arranged side-by-side, resulting in faster printing speeds and higher efficiency. However, due to its larger mass, it generates greater inertia during operation, requiring higher rigidity from the guide rails. This can reduce printing accuracy. In contrast to a single extruder head, a dual extruder head uses two extruders arranged side-by-side with fixed relative positions. Because it has two nozzles, the dual extruder head is mounted on a slider connected to the guide rail. The nozzle at the bottom of the extruder has four nozzle 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 must also be set in the printing software, such as the printing layer height and printing speed in the slicing software, to achieve higher printing quality and accuracy. The gear then tightens the feed filament.

[0009] In near-end feeding extruders, the feeder is mounted on the extrusion head (often a single component containing a heated aluminum block, heating rod, throat, nozzle, and radiator). The material is propelled by a feed motor that directly drives gears, using the frictional force of the gears 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 results in the extruder and print head moving together, leading to a large print head mass and significant inertia during printing, which can cause inaccuracies. Near-end feeding also requires high rigidity in the guide rails. In contrast, far-end feeding mounts the feeder at a distance from the extrusion head, 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 being mounted on the extrusion head. Compared to near-end feeding, far-end feeding requires greater torque to force the material into the print head.

[0010] The circuitry section of the 3D printer plays a crucial role in controlling the coordinated, orderly, and complete operation of the entire printing process. Some parameters in the firmware are modified as needed to meet printing requirements. It requires two 12V power supplies: one 11A to power the heated bed, and the other 5A to power the extruder, various axis motors, and fans. Since the author did not use a heated bed, only one 12V, 5A power supply is needed. Located in the upper right corner of the expansion board, it has limit switches for the X, Y, and Z directions, which control the printer's origin point during each operation. The stepper motor driver board connects to the stepper motors, enabling the main control board to control them and control the XYZ axis motors and the extruder. The stepper motor driver board is characterized by its simple stepping and direction control interface, offering five different stepping modes: full, half, 1 / 4, 1 / 8, and 1 / 16. An adjustable potentiometer allows adjustment of the maximum current output for higher stepping rates. It features overheat shutdown, undervoltage lockout, cross-current protection, grounding short-circuit protection, and load short-circuit protection. The driver board connects to the corresponding interface on the expansion board via pins. The software portion includes two main parts: host computer software and slave computer software, each further subdivided. Through the software's operation, the author can set and control the printing parameters on the main control board. The complete software operation process of a 3D printer is as follows: First, the author needs to model the part in a 3D modeling software on the computer, such as Solidworks, UG, or 3D Max. After creating the 3D model, the file is saved as an STL file. The STL file is opened in the slicing software Slic3r. Through a series of print settings, slicing is performed to generate code. The code is then opened in another host computer software, Pronterface, and connected to the motherboard. The lower-level software on the motherboard is the Marlin firmware, which has been pre-configured with parameters. After successful connection, the LED on the motherboard will flash. Once the heating element on the printer heats up and the temperature reaches the set temperature, printing begins. The software part of the printer is described in detail below. The lower-level software Marlin firmware is free software and can be directly used for software development. When using Marlin firmware in the 3D printer, the author only needs to download the firmware in the Arduino IDE software, find the Configuration.h file in the Marlin firmware, and modify the relevant code content according to their needs. The printer developed by the author requires the following modifications.

[0011] Current technical shortcomings: For FDM-3D multi-color selective printers, the current 2-input 1-output color mixing extruders cannot meet the requirements: they are characterized by very slow color changing, poor color mixing effect, easy thermal clogging, and large size. [Summary of the Invention]

[0012] Objective of this invention:

[0013] Solve the defects of current multi-color extruder components for fused deposition modeling (FDM-3D) in the industry, such as poor color mixing uniformity in dual-color mixing models.

[0014] Features of this invention:

[0015] By establishing a staggered feeding pattern with multiple intersecting channels in the color mixing chamber, mathematical boundary conditions for the feeding distribution are provided for good color mixing, thereby maximizing the goal of fast and uniform color mixing. Summary of the Invention:

[0017] The cross-flow three-dimensional printing dual-color mixing nozzle assembly of the present invention is specifically designed for FDM-3D printers. The main components required for the operation of an FDM-3D printer include: a feeding mechanism containing a feed tray for remotely pushing filament (the filament material is directly driven by a feeding motor to the gears, and the frictional thrust of the teeth is used to squeeze the filament into the throat); a mechanical stage that carries the extruder, which is either stationary or performs 1D, 2D, or 3D motion; and the matching worktable, which in turn performs 3D, 2D, 1D, or stationary motion; a structural housing that maintains the above-mentioned motion; an electronic control unit; a display screen, etc. The working principle has been described in detail in the [Background Art] section and is known prior art, so it will not be elaborated further.

[0018] The staggered flow channel 3D printing dual-color mixing nozzle assembly includes: a heated aluminum block, a flow channel cover plate, and nozzles; the heated aluminum block is machined with filament inlet holes (for connecting to the throat), a melt chamber, a melt channel, and a melt outlet surface, and the melt outlet surface is machined with staggered flow channels with isolation walls to isolate the different colors of melt; the flow channel cover plate is machined with melt outlet holes leading to their respective flow channels;

[0019] The assembly relationship is as follows: the flow channel interlaced 3D printing dual-color mixing nozzle assembly of the present invention is connected to the heat sink via a throat tube; the throat tube connecting to the 3D printer heat sink is inserted into the filament inlet hole of the heated aluminum block; the heat sink is the intermediate body connecting the heated aluminum block and the main body of the 3D printer; the flow channel cover plate covers the molten material outlet surface of the heated aluminum block, forming an isolation space between the two to isolate the molten materials of different colors; the nozzle with spray holes is screwed into the thread on the bottom of the heated aluminum block; the heating rod and temperature sensor are respectively inserted into the corresponding heating rod holes and other holes; the color mixing chamber refers to the space between the flow channel cover plate and the inner wall of the nozzle, up to the nozzle spray hole inlet; the heated aluminum block is heated by the heating rod in the heating rod hole and pushed by the printer pusher. The various colored filaments are fed into their respective filament inlets and melting chambers. After being melted, they flow through their respective melting channels to the melting outlets, then into their respective cross-sectional staggered flow channels, and finally out through the staggered outlets of the flow channel cover (the outlets for each color are staggered). They then enter the mixing chamber, a space formed by the flow channel cover and the inner wall of the nozzle. The flow channel cover can have a total of 2-50 staggered outlets, spaced apart for each color's melting outlet. This staggered arrangement of the outlets for each color ensures sufficient mixing and distribution of the two colors. Finally, after being sprayed out by the nozzle, the mixture exhibits excellent uniformity.

[0020] Further: The cross-sectional staggered flow channels are machined on the molten material outlet surface of the heated aluminum block, or on the flow channel cover plate; or corresponding cross-sectional staggered flow channels are machined on both the molten material outlet surface of the heated aluminum block and the flow channel cover plate.

[0021] Furthermore: the flow channels below the staggered outlets may be of equal or unequal depth; in the case of unequal depth, the height corresponding to the staggered outlets further away from the melt channel opening is higher, that is, the height of the space left below the staggered outlets is larger, so that the staggered outlets at different distances can obtain a consistent flow rate; or the flow channels are kept at equal depth, so that the opening diameters of the staggered outlets are different, with the opening diameter corresponding to the staggered outlets further away from the melt channel opening being larger, in order to balance the decrease in flow rate caused by the decrease in melt pressure.

[0022] The beneficial effects of this invention are:

[0023] It features uniform color mixing, is less prone to heat clogging, is easy to install and disassemble, has a small size, and does not change user habits. [Image Description]

[0024] Figure 1 Schematic diagram of the structure of a dual-color mixing nozzle assembly for 3D printing with staggered flow channels.

[0025] Figure 2 A schematic diagram of the cross-sectional structure of a dual-color mixing nozzle assembly for 3D printing with staggered flow channels. Figure 3 Schematic diagram of the assembly relationship between the melt outlet surface and the flow channel cover plate.

[0026] Figure 4 Diagrams showing the front and back of the heated aluminum block.

[0027] Attached image captions:

[0028] 1. Heating aluminum block

[0029] 2. Wire insertion hole

[0030] 3 Melting chamber 1

[0031] 4 Melting chamber 2

[0032] 5 Melting Channels

[0033] 6 Melt outlet surface

[0034] 7 cross-section staggered flow channel 1

[0035] 8 cross-section staggered flow channels 2

[0036] 9-channel cover plate

[0037] 10 Mixing Chamber

[0038] 11 nozzles

[0039] 12 melts, 1 outlet

[0040] 13 Melt material 2 outlet holes

[0041] 14. Airflow deflector

[0042] 15 nozzles

[0043] 16. Throat

[0044] 17 Heat sink

[0045] 18 heating rod holes

[0046] 19 flow channel steps 1

[0047] 20 flow channel steps 2

[0048] 21 Heated aluminum block front

[0049] 22 Heating aluminum block reverse side

[0050] Exploded view of nozzle assembly 23

[0051] [Implementation Case]

[0052] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments:

[0053] like Figure 1 , Figure 2 As shown:

[0054] In particular, as shown in the exploded view (23) of the nozzle assembly: the heat sink (17) is the intermediate body connecting the (heated) nozzle to the 3D printer body (directly fixed on the 3D printer). The flow channel interlaced three-dimensional printing dual-color mixing nozzle assembly of the present invention is connected to the heat sink (17) through the throat (16); the nozzle assembly includes: heating aluminum block (1), flow channel cover plate (9), nozzle (11), etc.; the assembly relationship is: the throat (16) is inserted into the filament inlet hole (2) of the heating aluminum block (1), and the flow channel cover plate (9) covers the heating aluminum block (1). On the molten material outlet surface (6) at the bottom of the aluminum block (1), a nozzle (11) with a spray hole (12) is screwed into the thread at the bottom of the heated aluminum block (1), and the heating rod and temperature sensor are respectively inserted into the corresponding heating rod hole and other holes; and a cross-sectional staggered flow channel with an isolation wall is machined on the molten material outlet surface (6) to isolate the various colored molten materials; and a molten material outlet hole leading to each flow channel is machined on the flow channel cover plate (9); in this way, when the flow channel cover plate is placed on the molten material outlet surface of the heated aluminum block, an isolation space is formed between the two to isolate the various colored molten materials;

[0055] During operation, the heating aluminum block (1) is heated by the heating rod, and the colored filaments pushed by the printer feeder enter the melting chamber 1 (3) and melting chamber 2 (4) respectively through the filament inlet (2). After being melted, they flow into the melting outlet surface (6) through their respective melting channels (5) and then into the cross-sectional cross-flow channel 1 (7) and cross-sectional cross-flow channel 2 (8). Figure 4 After being marked in the middle, it flows out from the staggered outlets of the flow channel cover (9) (the outlets of each color are staggered); then it enters the mixing chamber (10), which is a space formed by the flow channel cover (9) and the inner wall of the nozzle; after being sprayed out from the nozzle nozzle (15), it has good mixing uniformity.

[0056] like Figure 3 , Figure 4 As shown:

[0057] The front (21) of the heated aluminum block is connected to the throat pipe, and the bottom of the wire inlet (2) is machined with a feed hole: namely, the molten material channel (5); on the back (22) of the heated aluminum block, the positions of the cross-sectional intersecting flow channel 1 (7) and the cross-sectional intersecting flow channel 2 (8) can be seen, and an isolation wall (isolation protrusion between the two flow channels) is built between the two flow channels to prevent the two molten materials from mixing; as the flow channel moves further away from the molten material channel (5) in each flow channel, the pressure of the molten material will decrease; in order to ensure that the flow rate of each intersecting outlet is the same, steps of different heights are set below each intersecting outlet in the flow channel, the rule is: the further away from the molten material channel ( 5) The higher the height corresponding to the staggered outlet, the greater the height of the space left below the staggered outlet; that is, the height of the flow channel step 1 (19) is higher than the height of the flow channel step 2 (20); because the pressure of the molten material at the flow channel step 1 (19) is greater than the pressure of the molten material at the flow channel step 2 (20); the material gap (corresponding to the cross-sectional area) at the high-pressure flow channel step 1 (19) is smaller than the material gap at the flow channel step 2 (20) in order to obtain a consistent flow rate; a material hole is opened in the center of the guide plate (14) to assist in uniform mixing (because a concentration and diffusion process has been carried out).

[0058] The flow channel cover plate (9) has a total of 14 outlets for each color. Each color of material is assigned 7 melt 1 outlets (12) and 7 melt 2 outlets (13). The outlets of each color of material are arranged alternately. In this way, the two colors of material are evenly distributed initially, laying the foundation for the uniformity of mixing.

Claims

1. A flow channel interleaved three-dimensional printing dual color mixing nozzle assembly, the basic configuration comprising: Heated aluminum block, flow channel outlet cover plate, nozzle, etc.; The heated aluminum block is machined with filament inlet holes, melt channels, melt chambers, and melt outlet surfaces. The melt outlet surface has interlaced flow channels with isolation walls to isolate different colored melts. Melt outlet holes leading to their respective channels are machined on the flow channel outlet cover plate. The assembly relationship is as follows: the interlaced flow channel type 3D printing dual-color mixing nozzle assembly of this invention is connected to the heat sink via a throat tube; the throat tube connecting to the 3D printer heat sink is inserted into the filament inlet hole of the heated aluminum block; the heat sink is the intermediate body connecting the heated aluminum block and the 3D printer body; the nozzle with nozzles is screwed into the heating... On the threads at the bottom of the hot aluminum block, heating rods and temperature sensors are inserted into corresponding heating rod holes and other openings. The hot aluminum block is heated by the heating rods in the heating rod holes. The colored filaments pushed by the printer feeder enter their respective filament inlets and melt in their respective melting chambers. After being melted, they flow through their respective melting channels into the melting outlet surface, then into their respective cross-sectional intersecting flow channels, and finally out through the cross-sectional intersecting outlets of the flow channel outlet cover. After that, they enter the mixing chamber, which is the space formed by the flow channel outlet cover and the inner wall of the nozzle. Finally, they are ejected from the nozzle. Its features are as follows: the flow channel outlet cover plate covers the molten material outlet surface of the heated aluminum block, forming an isolation space between the two to isolate the molten materials of different colors; the color mixing chamber refers to the space between the flow channel outlet cover plate and the inner wall of the nozzle, up to the nozzle orifice inlet; the flow channel outlet cover plate can be provided with a total of 2-50 outlets of different colors, which are distributed to the molten material outlet holes of each color at intervals, so that the outlet holes of each color material are arranged alternately and alternately.

2. The dual color jetting head assembly for channel interleaved three-dimensional printing of claim 1, wherein: The cross-sectional staggered flow channels can be machined not only on the molten material outlet surface of the heated aluminum block, but also on the flow channel outlet cover plate, or corresponding cross-sectional staggered flow channels can be machined on both the molten material outlet surface of the heated aluminum block and the flow channel outlet cover plate.

3. The dual color jetting head assembly for channel interleaved three-dimensional printing of claim 1, wherein: The flow channels below the staggered outlets may have equal or unequal depths. In the case of unequal depths, the height corresponding to the staggered outlets further away from the melt channel opening is higher, meaning the height of the space left below the staggered outlets is larger. Alternatively, the flow channels may have equal depths, resulting in different opening diameters for each staggered outlet, with the opening diameter corresponding to the staggered outlets further away from the melt channel opening being larger.

Images