Particle material type 3D printer discharge port double-gear accurate control assembly and design method thereof

Abstract

The invention provides a granular material type 3D printer discharge port double-gear precise control assembly and a design method thereof, and belongs to the technical field of 3D printers. A double-gear flow control assembly with a driving gear meshed with a driven gear is arranged at a discharge port of a 3D printer, liquid is conveyed through reverse rotation of gears, and a sealing barrier is formed during rotation stopping; according to the 3D printer discharge port flow control device, the threaded rod guide heating shell is matched to melt particle materials, pressure buffering is provided through the liquid storage area, liquid is guided into the gear meshing area through the transition flow guide face, finally, the liquid is accurately discharged through the discharge pipe, and the technical problems that the 3D printer discharge port flow control precision is insufficient, and instantaneous sealing and blocking cannot be achieved are solved.

Description

Technical Field

[0001] This invention belongs to the field of 3D printer technology, and more specifically, relates to a dual-gear precision control component for the discharge port of a particulate material 3D printer and its design method. Background Technology

[0002] In particulate 3D printing technology, traditional discharge control systems primarily employ single-screw extrusion or single-gear pumping to deliver molten material to the printing nozzle. Single-screw extrusion systems control the discharge flow rate by adjusting the screw speed; however, due to the fixed gap between the screw and the housing, molten material continuously flows out of the discharge port under gravity, making precise flow control and instantaneous shut-off impossible. While single-gear pumping systems can provide stable delivery pressure, the single-sided sealing structure between the gear and the housing fails to form an effective physical barrier, causing material to slowly leak due to its own weight even when the machine stops. In current particulate 3D printing applications, because the discharge system cannot achieve a complete seal when the gear stops, frequent material dripping and stringing occur during printing, severely affecting the surface quality and dimensional accuracy of the printed parts. In other words, existing technologies suffer from insufficient flow control precision at the 3D printer discharge port and the inability to achieve instantaneous sealing. Summary of the Invention

[0003] In view of this, the present invention provides a dual-gear precision control component for the discharge port of a particulate material 3D printer and its design method, which can solve the technical problems of insufficient flow control precision at the discharge port of 3D printers and the inability to achieve instantaneous sealing and blocking in the prior art.

[0004] The present invention is implemented as follows: The present invention provides a dual-gear precision control component for the discharge port of a particulate material 3D printer and its design method. The flow control component includes a drive gear and a driven gear, which are meshed together. The center of the drive gear is fixedly connected to a rotating rod, and the center of the driven gear is fixedly connected to a support rod. Through the meshing of the drive gear and the driven gear, the liquid conveyed by the pusher component is sealed between the pusher component and the flow control component. The rotation of the rotating rod and the support rod drives the liquid to be conveyed to the bottom of the flow control component. When the drive gear and the driven gear stop rotating, the meshing position of the drive gear and the driven gear forms a completely sealed physical barrier to block the natural flow of the liquid under the action of gravity.

[0005] The housing includes a screw guide heating housing and a liquid sealing housing. The screw guide heating housing is sleeved on the outside of the pusher assembly, and the liquid sealing housing is located at the bottom of the housing and covers the middle position between the pusher assembly and the flow control assembly, as well as the flow control assembly.

[0006] The screw guide heating shell has a cylindrical structure, and a spiral heating channel is formed between the inner wall surface of the screw guide heating shell and the outer spiral surface of the pusher assembly.

[0007] The screw guide heating shell is made of aluminum alloy, and the outer wall surface of the screw guide heating shell is provided with multiple longitudinal heat dissipation ribs, which are evenly distributed along the axial direction of the screw guide heating shell.

[0008] The liquid sealing shell has a flat cylindrical cavity structure, and the inner diameter of the liquid sealing shell matches the sum of the tip circle diameters of the driving gear and the driven gear.

[0009] The material feeding component and the flow control component are provided with a liquid storage area, which has an annular cavity structure.

[0010] The liquid sealing shell has a discharge pipe at its bottom, which is connected to the liquid sealing shell. The discharge pipe has a frustum-shaped structure.

[0011] In this configuration, the number of teeth on the driving gear and the driven gear are the same, with the driving gear having 12 to 18 teeth, and the tip circle diameter of the driven gear being equal to that of the driving gear.

[0012] The invention relates to a dual-gear precision control component for the discharge port of a particulate material 3D printer as described in any one of claims 1 to 8. It determines the basic parameters of the driving and driven gears based on the material delivery flow requirements of the 3D printer, collects multiple sets of liquid delivery flow data for the dual-gear component at different speeds, establishes a correlation dataset between gear parameters and delivery volume, designs the volume of the liquid storage area based on the single meshing delivery volume, determines the optimal range of the ratio coefficient, establishes an upper-level game model with optimal sealing performance as the objective and a lower-level game model with maximum delivery efficiency as the objective, correlates the gear meshing contact area as a coupling term, uses the upper-level game model to calculate the optimal meshing clearance and optimal meshing depth, and uses the lower-level game model to calculate the optimal tooth width and determine the range of coefficient values ​​in the tooth width calculation.

[0013] The method for establishing the associated dataset is to pair and record the tooth groove depth, tooth width, tooth root circle radius, tooth tip circle radius, and corresponding single meshing conveying volume under different gear parameter combinations, forming a multidimensional data table containing gear geometric parameters and conveying performance parameters.

[0014] The discharge pipe is made of stainless steel and is connected to the bottom of the liquid sealing shell by a threaded connection.

[0015] Both the driving gear and the driven gear are made of stainless steel and undergo heat treatment to increase their hardness to 45-55 Rockwell hardness. The tooth surfaces of the driving gear and the driven gear are precision ground to make the tooth surface roughness less than 0.4μm.

[0016] It also includes adjusting the liquid output flow rate of the discharge pipe by adjusting the rotation speed of the drive gear and the driven gear, with the drive gear and the driven gear rotating in opposite directions.

[0017] It also includes that the discharge pipe is located directly below the meshing position of the driving gear and the driven gear, and the central axis of the discharge pipe is perpendicular to the line connecting the centers of the driving gear and the driven gear.

[0018] It also includes the fact that the shape of the teeth of the driving gear and the driven gear is one of the following: pointed, arc-shaped, or polygonal plane, and the shape of the teeth of the driving gear and the driven gear is the same.

[0019] It also includes a rotating rod connected to the power system of the 3D printer. The rotating rod has a cylindrical structure and a diameter of 8~15mm. One end of the rotating rod is fixedly connected to the center hole of the drive gear through a keyway connection.

[0020] The support rod has a cylindrical structure, and its diameter is equal to that of the rotating rod. One end of the support rod is fixedly connected to the center hole of the driven gear through a keyway connection, and the other end of the support rod is fixed to the top wall of the liquid sealing shell.

[0021] The feeding assembly is a rotary screw with an Archimedean spiral structure. The outer diameter of the rotary screw is 25~4mm, the helix angle is 15~25°, and the pitch is 20~35mm.

[0022] The objective function of the upper-level game model optimizes the gear's sealing performance by minimizing the leakage risk index. This is achieved by weighted summation of the squared differences between the ratio of meshing clearance to gear module and the standard meshing clearance ratio, the squared differences between the ratio of meshing depth to tooth height and the standard meshing depth ratio, and the ratio of gear meshing contact area to standard meshing contact area. The objective function of the lower-level game model optimizes the gear's conveying efficiency by maximizing the conveying volume per unit time. This is achieved by multiplying the ratio of tooth width to the height of the liquid sealing shell cavity, the natural logarithm of the ratio of the number of teeth to the standard number of teeth, and the ratio of gear meshing contact area to the standard meshing contact area to obtain the normalized value of the conveying volume per unit time.

[0023] This invention employs a double-gear sealing structure formed by the meshing of a driving gear and a driven gear. The counter-rotating motion of the two gears transports liquid material from the liquid storage area to the discharge pipe. When the gears stop rotating, the meshing point forms a completely sealed physical barrier, preventing the natural flow of liquid under gravity. A precise meshing clearance is maintained between the tooth tips and roots at the meshing point of the double gears. This clearance value is precisely calculated based on the gear module to ensure that the gears will not jam under thermal expansion conditions, while simultaneously ensuring the sealing performance at the meshing point to prevent liquid leakage from the tooth gaps. The tooth groove volume of the gears is geometrically optimized, so that the delivery flow rate per unit time corresponds linearly to the gear rotation speed, thereby achieving precise flow control. In summary, this invention solves the technical problems mentioned in the background art regarding insufficient flow control accuracy at the 3D printer discharge port and the inability to achieve instantaneous sealing and blocking, through a double-gear meshing sealing structure. Attached Figure Description

[0024] Figure 1 A schematic diagram of a dual-gear precision control component for the discharge port of a particulate material 3D printer;

[0025] Figure 2 This is a schematic diagram of the internal structure of a dual-gear precision control component at the discharge port of a particulate material 3D printer.

[0026] Figure 3 This is a schematic diagram of the material feeding assembly;

[0027] Figure 4 This is a schematic diagram of the flow control component.

[0028] Figure 5 This is a flowchart of the method of the present invention.

[0029] The attached diagram lists the components represented by each number as follows:

[0030] 1. Housing; 11. Screw guide heating housing; 12. Liquid sealing housing; 2. Pushing assembly; 3. Flow control assembly; 31. Drive gear; 311. Rotating rod; 32. Driven gear; 321. Support rod; 4. Discharge pipe. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0032] The utility model patent with application number 202620089360.1, entitled "An Extrusion Flow Adjustment Component for a 3D Printer for Particulate Materials", proposes a structure using a two-gear forming control component. This invention makes more detailed adjustments and expansions based on the above utility model patent. The specific structure and design are described as follows.

[0033] like Figures 1-4 The diagram shows a structural schematic of a dual-gear precision control assembly for the discharge port of a particulate material 3D printer, provided by the first aspect of the present invention. The assembly includes a housing 1, a feeding assembly 2, and a flow control assembly 3. The housing is located outside the feeding assembly and the flow control assembly. The top of the feeding assembly is connected to the power system of the 3D printer and is used to rotate and transport the housing material into the interior for heating and pressurization. The flow control assembly is located at the bottom of the feeding assembly and includes a driving gear 31 and a driven gear 32. The driving gear and the driven gear are meshed. The center of the driving gear is fixedly connected to the rotating rod 311, and the center of the driven gear is fixedly connected to the support rod 321. The connection between the driving gear and the driven gear seals the liquid transported by the feeding assembly between the feeding assembly and the flow control assembly, and the rotation of the rotating rod and the support rod drives the liquid to be transported below the flow control assembly.

[0034] This invention incorporates a dual-gear precision flow control and sealing barrier technology. The dynamic sealing barrier formed by meshing gears enables precise delivery and instantaneous cut-off of molten material. The housing includes a screw guide heating shell 11 and a liquid sealing shell 12. The screw guide heating shell is sleeved on the outside of the pusher assembly and has a cylindrical structure. A spiral heating channel is formed between the inner wall of the screw guide heating shell and the outer spiral surface of the pusher assembly. The wall thickness of the screw guide heating shell is 5mm~8mm. The screw guide heating shell is made of aluminum alloy to provide good thermal conductivity. Multiple longitudinal heat dissipation ribs are provided on the outer wall of the screw guide heating shell along its axial direction. The heat dissipation ribs are evenly distributed in the direction of heat dissipation, with a spacing of 10mm to 15mm between adjacent ribs. The liquid sealing shell is located at the bottom of the housing and covers the middle position of the pusher assembly and the flow control assembly, as well as the flow control assembly. The liquid sealing shell has a flat cylindrical cavity structure with an inner cavity height of 20mm to 35mm. The inner cavity diameter of the liquid sealing shell matches the sum of the addendum circle diameters of the drive gear and the driven gear. The liquid sealing shell is connected to the screw guide heating shell via a flange. The outer diameter of the flange is larger than the outer diameter of the screw guide heating shell. The flange and the screw guide heating shell are fastened together by multiple bolts. The bolts are evenly distributed along the circumference of the flange and number 6 to 10.

[0035] A liquid storage area is provided between the feeding assembly and the flow control assembly. The liquid storage area has an annular cavity structure. The inner diameter of the liquid storage area is adapted to the bottom diameter of the feeding assembly, and the outer diameter of the liquid storage area is tangent to the inner wall of the liquid sealing shell. The height of the liquid storage area is 8mm~15mm, and the volume of the liquid storage area is... The single-meshing conveying volume of the driving gear and the driven gear The relationship between them is satisfied The equation is used to ensure that the liquid storage area has sufficient buffer capacity to accommodate pressure fluctuations during intermittent gear delivery, and the input includes the tooth groove depth of the drive gear. The tooth width of the driving gear The tooth groove depth of the driven gear The tooth width of the driven gear Effective length of gear meshing The output is the design volume of the liquid storage area. The value of the coefficient k ranges from 15 to 25. When the coefficient k is less than 15, the buffering capacity of the liquid storage area is insufficient, resulting in increased pressure pulsation. When the coefficient k is greater than 25, the volume of the liquid storage area is too large, resulting in prolonged material residence time and affecting printing accuracy.

[0036] The bottom of the liquid sealing shell is provided with a discharge pipe 4, which is connected to the liquid sealing shell to discharge the liquid conveyed by the flow control component. The discharge pipe has a frustum-shaped structure, with an upper opening diameter of 8mm~12mm, a lower opening diameter of 0.4mm~1.2mm, a taper angle of 15°~30°, and a length of 25mm~40mm. The discharge pipe is made of stainless steel to withstand the corrosion of high-temperature molten materials. The inner wall surface of the discharge pipe is precision polished to achieve a surface roughness of less than 0.8μm to reduce liquid flow resistance. The discharge pipe is connected to the bottom of the liquid sealing shell by a threaded connection, and a sealing ring is provided at the threaded connection. The sealing ring is made of high-temperature resistant silicone rubber and has a cross-sectional diameter of 2mm~3mm. The length of the tapered section of the discharge pipe is... The diameter of the upper opening of the discharge pipe and the diameter of the lower opening The relationship between them is satisfied The equation is used to accurately calculate the length of the tapered section based on the diameters and taper angles of the upper and lower ends of the discharge pipe, thereby ensuring a smooth transition in liquid flow. The inputs include the upper opening diameter of the discharge pipe. The lower opening diameter of the discharge pipe The taper angle The output is the length of the conical section of the discharge pipe. When the deviation between the length of the conical section and the calculated value exceeds 0.5 mm, the flow of liquid in the conical section will generate eddies, increasing the flow resistance.

[0037] The driving gear and the driven gear have the same number of teeth, with the driving gear having 12 to 18 teeth and the driven gear having the same number of teeth to achieve synchronous reverse rotation. The tip circle diameter of the driving gear is 30 mm to 45 mm, and the tip circle diameter of the driven gear is equal to that of the driving gear. The root circle diameter of the driving gear is 25 mm to 38 mm, and the root circle diameter of the driven gear is equal to that of the driving gear. The tooth width of the driving gear is 15 mm to 25 mm, and the tooth width of the driven gear is equal to that of the driving gear to ensure uniform distribution of contact area during meshing. Both the driving gear and the driven gear are made of stainless steel and undergo heat treatment to increase their hardness to 45 HRC to 55 HRC. The tooth surfaces of the driving gear and the driven gear are precision ground to achieve a surface roughness of less than 0.4 μm.

[0038] The liquid output flow rate of the discharge pipe is adjusted by regulating the rotational speed of the driving gear and the driven gear. The driving gear and the driven gear rotate in opposite directions. When the rotational speed of the driving gear increases from 10 rpm to 60 rpm, the liquid output flow rate of the discharge pipe correspondingly increases from 0.5 rpm to 60 rpm. / s increase ~3 / s, when the driving gear and the driven gear stop rotating, the meshing position of the driving gear and the driven gear forms a completely sealed physical barrier, blocking the natural flow of liquid under gravity. The tooth groove volume of the driving gear The root circle radius of the driving gear Tooth tip circle radius Tooth width The relationship between them is satisfied The equation is used to accurately calculate the volume of a single tooth groove based on the gear's geometry, thereby determining the gear's conveying capacity. The input includes the root circle radius of the driving gear. The tooth tip circle radius of the driving gear The tooth width of the driving gear The number of teeth of the driving gear The output is the volume of a single tooth groove. When the volume of the tooth groove increases, the output flow rate per unit time of the discharge pipe increases accordingly.

[0039] The discharge pipe is located directly below the meshing position of the driving gear and the driven gear. The central axis of the discharge pipe is perpendicular to the line connecting the centers of the driving gear and the driven gear. The geometric center of the upper opening of the discharge pipe is located directly below the meshing node of the driving gear and the driven gear, with a vertical distance of 3mm to 8mm. The minimum gap between the lowest point of the driving gear and the edge of the upper opening of the discharge pipe is 1mm to 3mm. The minimum gap between the lowest point of the driven gear and the edge of the upper opening of the discharge pipe is equal to the minimum gap between the lowest point of the driving gear and the edge of the upper opening of the discharge pipe. This ensures that the liquid flows evenly into the discharge pipe from the meshing area. When the gap between the lowest point of the driving gear and the driven gear and the edge of the upper opening of the discharge pipe is less than 1mm, the gears are prone to interference and collision with the discharge pipe during rotation. When the gap is greater than 3mm, splashing will occur during the liquid flow from the meshing area to the discharge pipe, reducing the conveying accuracy.

[0040] The teeth of the driving gear and the driven gear are shaped like a pointed, arc-shaped, or polygonal plane. The identical tooth shape of the driving gear and the driven gear ensures the sealing of the meshing gears. When the tooth shape is pointed, the tooth tip has a sharp vertex structure with a tip angle of 60°~90°. The tooth flank of the pointed tooth is a straight inclined surface, and the angle between the tooth flank and the radial direction of the gear is 25°~40°. When the tooth shape is arc-shaped, the tooth tip has a rounded convex structure. The radius of curvature of the arc is 2mm~5mm. The tooth flank of the arc-shaped tooth is an involute surface. The ratio of the base circle radius of the involute to the root circle radius of the gear is 0.7~0.85. When the shape of the tooth is a polygonal plane, the tooth tip is a planar structure. The width of the planar structure is 0.15~0.25 times the difference between the radius of the tip circle and the root circle. The tooth flank of the polygonal planar tooth is a trapezoidal inclined surface. The upper base of the trapezoidal inclined surface is connected to the tooth tip plane, and the lower base of the trapezoidal inclined surface is tangent to the root circle.

[0041] The meshing clearance between the tooth tip of the driving gear and the tooth root of the driven gear The relationship between the gear and the module m is as follows: The equation is used to determine a reasonable meshing clearance based on the gear module, thereby preventing gear jamming while ensuring sealing performance. The inputs include the module m of the driving gear, the number of teeth of the driving gear, and the number of teeth of the driven gear. The output is the design value of the meshing clearance. When the meshing clearance is less than... During rotation, the driving gear and the driven gear experience jamming due to the thermal expansion of the materials causing their tooth surfaces to press against each other. When the meshing clearance is greater than... When the sealing performance at the meshing point of the driving gear and the driven gear decreases, liquid leaks from the tooth gap, and the meshing depth of the driving gear and the driven gear... With the tooth height of the gear The relationship between them is satisfied The equation is used to determine the insertion depth of the teeth during gear meshing, thereby ensuring sealing effect and transmission smoothness. The input includes the tooth height of the gear. The module m of the gear is output as the meshing depth. When the meshing depth is less than... Excessive sealing clearance at the gear meshing point leads to increased liquid leakage. When the meshing depth is greater than... Excessive meshing of gears can lead to accelerated wear on the gear teeth.

[0042] The rotating rod is connected to the power system of the 3D printer. The rotating rod has a cylindrical structure with a diameter of 8mm-15mm and a length of 50mm-80mm. One end of the rotating rod is fixedly connected to the center hole of the drive gear via a keyway connection. The keyway has a length of 15mm-25mm, a width of 3mm-6mm, and a depth of 2mm-4mm. The other end of the rotating rod is connected to the output shaft of the 3D printer's power system via a coupling. The coupling uses a flexible coupling structure to absorb vibration and impact during transmission. The rotating rod is made of alloy steel. The surface hardness reaches 40HRC~50HRC after tempering treatment. The surface of the rotating rod is chrome-plated to form a hard coating with a thickness of 0.02mm~0.05mm to improve wear resistance. The rotating rod passes through the top wall of the liquid sealing shell. The rotating rod and the top wall of the liquid sealing shell are rotatably connected by a bearing. The bearing adopts a deep groove ball bearing structure. The inner ring of the bearing is interference-fitted with the rotating rod, and the outer ring of the bearing is interference-fitted with the bearing seat hole on the top wall of the liquid sealing shell. The interference between the diameter of the bearing seat hole and the outer diameter of the bearing outer ring is 0.01mm~0.03mm.

[0043] The support rod has a cylindrical structure, and its diameter is equal to that of the rotating rod. The length of the support rod is 30mm to 50mm. One end of the support rod is fixedly connected to the center hole of the driven gear via a keyway connection. The keyway on the support rod has the same dimensions as the keyway on the rotating rod. The other end of the support rod is fixed to the top wall of the liquid sealing shell. The support rod achieves rotational movement through bearing support. The bearing structure between the support rod and the top wall of the liquid sealing shell is the same as the bearing structure between the rotating rod and the liquid sealing shell. The axis of the support rod is parallel to the axis of the rotating rod and lies in the same horizontal plane. The center distance between the axes of the support rod and the rotating rod is... The center distance is equal to the sum of the pitch circle radii of the driving gear and the driven gear. Satisfying the relation The equation is used to determine the precise distance between the axes of two gears based on the gear module and the number of teeth, thereby ensuring correct gear meshing. The inputs include the gear module m and the number of teeth of the driving gear. The number of teeth of the driven gear The output is the center distance between the support rod and the rotating rod. When the deviation between the actual value and the calculated value of the center distance exceeds 0.05mm, the meshing clearance between the driving gear and the driven gear changes significantly, affecting the sealing performance and transmission accuracy.

[0044] The feeding assembly is a rotary screw with an Archimedean spiral structure. The outer diameter of the rotary screw is 25mm~40mm, the helix angle is 15°~25°, the pitch is 20mm~35mm, and the effective working length is 100mm~200mm. The top of the rotary screw is connected to the 3D printer's power system via a coupling, and the bottom of the rotary screw extends above the liquid storage area. The vertical distance between the bottom surface of the rotary screw and the top surface of the liquid storage area is 5mm~12mm. The rotary screw is made of stainless steel, and its surface is nitrided to a thickness of 0.1mm. A hardened layer of approximately 0.3 mm is used to improve wear resistance and corrosion resistance. The spiral groove depth of the rotating screw is 5 mm to 10 mm, and the spiral groove width is 8 mm to 15 mm. During rotation, the rotating screw transports granular material from top to bottom, where it gradually melts and transforms into a liquid state under the heating effect of the screw guide heating shell. The rotational speed of the rotating screw is 5 rpm to 50 rpm. When the rotational speed is lower than 5 rpm, the material conveying speed is too slow, resulting in reduced production efficiency. When the rotational speed is higher than 50 rpm, the material's residence time in the screw guide heating shell is insufficient, leading to incomplete melting. The spiral groove volume of the rotating screw... With the outer diameter of the rotating screw pitch Spiral groove depth The relationship between them is satisfied The equation is used to calculate the volume within a single pitch based on the geometric parameters of the rotating screw, thereby determining the material conveying rate. The inputs include the outer diameter of the rotating screw. The pitch of the rotating screw The depth of the helical groove of the rotating screw The output is the volume of the spiral groove within a single pitch. When the volume of the spiral groove increases, the single-turn delivery of the rotating screw increases accordingly.

[0045] A transition guide surface is provided at the bottom of the liquid storage area. The transition guide surface has a conical structure, with its top end connected to the bottom edge of the liquid storage area and its bottom end tangent to the plane containing the addendum circles of the driving gear and the driven gear. The cone angle of the transition guide surface is 45°~70°. The surface of the transition guide surface is precision polished to achieve a surface roughness of less than 0.6μm to guide the liquid to flow smoothly to the meshing area of ​​the driving gear and the driven gear. Multiple spiral guide grooves are provided on the transition guide surface, with 3~6 grooves evenly distributed circumferentially along the transition guide surface. The depth of each groove is 1mm~3mm, and the width is 2mm~5mm. The helix angle of the grooves matches the helix angle of the rotating screw to continue the pushing action of the rotating screw and reduce eddy current losses during liquid flow. The height of the transition guide surface... With respect to the outer diameter of the liquid storage area The gear tooth tip circle diameter The cone angle The relationship between them is satisfied The equation is used to calculate the height of the transition guide surface based on the dimensions of the liquid storage area and the gear, as well as the cone angle, to ensure a smooth transition of liquid flow. The input includes the outer diameter of the liquid storage area. The gear tooth tip circle diameter The cone angle of the transition guide surface The output is the height of the transition guide surface. When the height of the transition guide surface deviates from the calculated value by more than 1 mm, the liquid flow will generate turbulence and increase flow loss.

[0046] The vertical clearance between the root circle of the driving gear and the driven gear and the inner bottom surface of the liquid sealing shell is 2mm~6mm. When the vertical clearance is less than 2mm, the driving gear and the driven gear are prone to friction and wear with the inner bottom surface of the liquid sealing shell during rotation. When the vertical clearance is greater than 6mm, the liquid forms a large retention space below the driving gear and the driven gear, resulting in reduced material utilization. The vertical clearance between the tip circle of the driving gear and the inner top surface of the liquid sealing shell is 3mm~8mm. The vertical clearance between the tip circle of the driven gear and the inner top surface of the liquid sealing shell is equal to the vertical clearance between the tip circle of the driving gear and the inner top surface of the liquid sealing shell. The radial clearance between the outer side of the tip circle of the driving gear and the inner wall of the liquid sealing shell is 1mm~4mm. The radial clearance between the outer side of the tip circle of the driven gear and the inner wall of the liquid sealing shell is 1mm~4mm. The radial clearance is used to accommodate a small amount of liquid squeezed out during gear rotation and to prevent the liquid from forming a high-pressure area on the outside of the gear.

[0047] The height of the heat dissipation ribs of the screw guide heating shell With the outer diameter of the screw guide heating shell The relationship between them is satisfied ~ The equation is used to determine the height of the heat dissipation ribs based on the outer diameter of the housing, thereby optimizing the heat dissipation effect. The input includes the outer diameter of the screw-guided heating shell. The output is the height of the heat dissipation rib. When the height of the heat dissipation rib is less than... Insufficient heat dissipation area leads to excessively high casing temperature; when the height of the heat dissipation ribs is greater than... Excessive length of the heat dissipation ribs reduces structural strength and increases space occupation. The thickness of the heat dissipation ribs is 2mm to 4mm. The heat dissipation ribs are made of the same aluminum alloy material as the screw guide heating shell and are formed into an integrated structure with the screw guide heating shell through extrusion molding.

[0048] The inner cavity height of the liquid sealing shell The tooth tip circle diameter of the driving gear The relationship between them is satisfied ~ The equation is used to determine the inner cavity height of the liquid sealing shell based on the gear diameter, thereby ensuring sufficient rotation space for the gear and a suitable inner cavity volume. The input includes the tip circle diameter of the driving gear. The output is the inner cavity height of the liquid-sealed shell. When the inner cavity height is less than... The insufficient clearance between the gear and the top and bottom surfaces of the housing restricts rotation. When the height of the inner cavity is greater than... Excessive internal volume can lead to increased liquid retention, affecting material flow efficiency. The wall thickness of the liquid sealing shell is 4mm to 8mm, and the liquid sealing shell is made of stainless steel to withstand the pressure and high temperature environment of the internal liquid.

[0049] The tooth width of the drive gear The number of teeth of the driving gear The inner cavity height of the liquid sealing shell The center distance between the driving gear and the driven gear The relationship between the gear module m and the given gear module m is as follows: The equation is used to determine the gear tooth width based on the inner cavity height of the liquid sealing shell, the number of teeth, the module, and the center distance of the gear, thereby achieving optimal meshing effect and conveying capacity while ensuring sufficient rotational space for the gear. The inputs include the inner cavity height of the liquid sealing shell. The number of teeth of the driving gear The gear module m, the center distance between the driving gear and the driven gear The output is the tooth width of the driving gear, and the coefficient The value range of the coefficient is 0.45 to 0.55. The value range is 2mm~4mm, when the number of teeth When the center distance increases, the addendum circle diameter of the gear increases accordingly, resulting in an increase in the space occupied by the gear within the liquid-sealed housing. This necessitates a reduction in tooth width to maintain a reasonable axial clearance. When the tooth width is increased, the internal space of the liquid sealing shell expands accordingly, allowing the tooth width to be appropriately increased to improve the conveying volume of a single meshing. When the calculated tooth width value is less than 12mm, the meshing contact area of ​​the gear is insufficient, resulting in excessive pressure on the tooth surface and a small liquid volume conveyed in a single meshing, affecting the discharge efficiency. When the calculated tooth width value is greater than 28mm, the axial clearance between the gear and the inner wall of the liquid sealing shell is too small, causing interference friction between the gear and the shell when the gear rotates and increasing the transmission resistance.

[0050] The second aspect of this invention provides a design method for a dual-gear precision control component for the discharge port of a particulate material 3D printer, such as... Figure 5 As shown, it includes the following steps:

[0051] S01. Determine the basic parameters of the driving gear and driven gear according to the material delivery flow requirements of the 3D printer, including the number of teeth ranging from 12 to 18, the tooth tip circle diameter ranging from 30mm to 45mm, and the tooth width ranging from 15mm to 25mm.

[0052] S02. Collect liquid transport flow data of multiple sets of dual gear assemblies at different speeds, the speed range being 10 rpm to 60 rpm. Simultaneously measure the tooth groove depth, tooth width, tooth root circle radius, and tooth tip circle radius of each gear set, calculate the single meshing transport volume, and establish a correlation dataset between gear parameters and transport volume.

[0053] S03. Based on the correspondence between gear parameters and single meshing conveying volume in the associated dataset, design the volume of the liquid storage area with the single meshing conveying volume as the benchmark. By comparing the pressure fluctuation amplitude under different volume ratios, determine the optimal range of the ratio coefficient k between the liquid storage area volume and the single meshing conveying volume.

[0054] S04. Collect pressure fluctuation data under different ratio coefficients k, record the correspondence between the pressure fluctuation peak and the ratio coefficient k, reduce the value of the ratio coefficient k when the pressure fluctuation peak exceeds the set threshold, increase the value of the ratio coefficient k when the material residence time exceeds the allowable range, and finally determine the value range of the ratio coefficient k as 15~25.

[0055] S05. Establish an upper-level game model with the goal of optimizing sealing performance and a lower-level game model with the goal of maximizing conveying efficiency. The objective function input of the upper-level game model includes meshing clearance, meshing depth, and gear module. The objective function input of the lower-level game model includes tooth width, number of teeth, and height of the liquid sealing shell cavity. The two objective functions are associated through the gear meshing contact area as a coupling term.

[0056] S06. The optimal meshing clearance and optimal meshing depth are calculated using an upper-level game model. The calculation result of the optimal meshing clearance is used to determine the gear machining accuracy requirements, and the calculation result of the optimal meshing depth is used to determine the gear tooth height design value.

[0057] S07. Calculate the optimal tooth width using a lower-level game theory model, and determine the coefficients in the tooth width calculation based on the correlation between the optimal tooth width and the height of the liquid-sealed shell cavity, the number of gear teeth, and the gear module. With coefficient The range of values ​​for ;

[0058] S08, Coefficient Within the range of 0.40 to 0.60, with a step size of 0.05 and a coefficient Combined tests were conducted within the range of 1mm to 5mm in increments of 0.5mm. The calculated tooth width value, corresponding axial clearance, and gear meshing contact area were recorded for each coefficient. When the axial clearance was less than 1mm, the coefficient was increased. And reduce the coefficient When the bearing pressure on the tooth surface exceeds the allowable stress of the material, the reduction factor is applied. And increase the coefficient The coefficient will eventually be The coefficient is determined to be 0.45~0.55. The thickness is determined to be 2mm~4mm.

[0059] The method for establishing the associated dataset is to pair and record the tooth groove depth, tooth width, tooth root circle radius, tooth tip circle radius, and corresponding single meshing conveying volume under different gear parameter combinations, forming a multidimensional data table containing gear geometric parameters and conveying performance parameters.

[0060] The pressure fluctuation amplitude is measured by installing a pressure sensor in the liquid storage area and recording the difference between the maximum and minimum pressure values ​​in the liquid storage area during gear meshing and conveying. The sampling frequency of the pressure sensor is 100Hz~200Hz.

[0061] The threshold value for the pressure fluctuation peak is determined based on the printing accuracy requirements of the 3D printer. When the printing accuracy requirement is 0.1 mm, the threshold value is set to 0.05 MPa, and when the printing accuracy requirement is 0.05 mm, the threshold value is set to 0.03 MPa.

[0062] The allowable range of material residence time is determined based on the thermal stability of the material. For materials with good thermal stability, the allowable range is 30s to 60s, and for materials with poor thermal stability, the allowable range is 10s to 20s. The material residence time is calculated by dividing the volume of the liquid storage area by the liquid delivery flow rate.

[0063] The objective function of the upper-level game model is used to optimize the sealing performance of the gear by minimizing the leakage risk index. The inputs include meshing clearance, meshing depth, and gear module, and the outputs are the optimal meshing clearance and optimal meshing depth. The objective function of the upper-level game model is expressed as follows: the square of the difference between the ratio of meshing clearance to gear module and the standard meshing clearance ratio, the square of the difference between the ratio of meshing depth to tooth height and the standard meshing depth ratio, and the ratio of gear meshing contact area to standard meshing contact area are weighted and summed. The result of the weighted summation is the leakage risk index. The constraints of the upper-level game model are that the meshing clearance is within the range of 0.05 to 0.15 times the gear module and the meshing depth is within the range of 0.6 to 0.8 times the tooth height. The standard meshing clearance ratio is 0.1, the standard meshing depth ratio is 0.7, and the standard meshing contact area is 0.6 times the product of tooth width and tooth height.

[0064] The objective function of the lower-level game model is used to optimize the conveying efficiency of the gear by maximizing the conveying volume per unit time. The inputs include tooth width, number of teeth, and height of the liquid sealing shell cavity. The output is the optimal tooth width. The objective function of the lower-level game model is expressed as follows: multiply the ratio of tooth width to height of the liquid sealing shell cavity, the natural logarithm of the ratio of number of teeth to standard number of teeth, and the ratio of gear meshing contact area to standard meshing contact area. The result of the multiplication operation is the normalized value of the conveying volume per unit time. The constraints of the lower-level game model are that the tooth width is in the range of 12mm to 28mm and the axial clearance is greater than 1mm. The standard number of teeth is 15.

[0065] The gear meshing contact area is calculated by multiplying the tooth width by the meshing depth. The gear meshing contact area serves as a coupling term between the upper-level game model and the lower-level game model. When the optimal meshing depth calculated by the upper-level game model increases, the gear meshing contact area increases accordingly, thereby affecting the normalized value of the unit time transport volume in the lower-level game model.

[0066] The calculation result of the optimal meshing clearance is used to determine the accuracy control range between the addendum circle and the dedendum circle during gear machining. When the optimal meshing clearance is 0.08 times the gear module, the gear machining accuracy is required to be controlled within 0.02mm.

[0067] The calculation result of the optimal meshing depth is used to determine the tooth height design value of the gear. The tooth height design value is calculated by dividing the optimal meshing depth by the standard meshing depth ratio. When the optimal meshing depth is 5 mm, the tooth height design value is 7.14 mm.

[0068] The axial clearance is measured at the distance between the gear end face and the inner wall of the liquid sealing shell. When the axial clearance is less than 1 mm, the gear will rub against the shell during rotation, leading to increased wear. When the axial clearance is greater than 5 mm, the gear will wobble in the axial direction, affecting the meshing accuracy.

[0069] The calculation method for the bearing pressure on the tooth surface is to divide the torque transmitted by the gear by the meshing contact area of ​​the gear. The allowable stress of the material is determined according to the yield strength of the gear material. When the gear material is stainless steel and the hardness is 45HRC~55HRC, the allowable stress of the material is 800MPa~1000MPa.

[0070] The leakage risk index is a comprehensive indicator for assessing the possibility of liquid leakage at the gear meshing point. The smaller the leakage risk index value, the better the sealing performance. When the leakage risk index is less than 0.15, the liquid leakage at the gear meshing point is less than 1% of the total delivery volume.

[0071] The normalized value of the conveying volume per unit time is a dimensionless index for evaluating the conveying efficiency of the gear. The larger the normalized value of the conveying volume per unit time, the higher the conveying efficiency. When the normalized value of the conveying volume per unit time is greater than 0.85, the actual conveying flow rate of the gear reaches more than 90% of the theoretical conveying flow rate.

[0072] It should be noted that this invention also solves the following technical problem: In granular material 3D printing systems, pressure pulsations and flow instability easily occur when molten material enters the gear flow control area from the screw conveying area. This invention addresses this by setting a liquid storage area between the feeding assembly and the flow control assembly. The volume of this storage area is designed to be 15-25 times the volume of a single gear engagement, providing sufficient buffer space to absorb pressure fluctuations caused by intermittent screw feeding. The transition guide surface at the bottom of the liquid storage area adopts a conical structure and is equipped with a spiral guide groove. The spiral angle of the guide groove matches the spiral helix angle of the rotating screw, ensuring that the liquid maintains a flow trend consistent with the screw feeding direction as it flows from the storage area to the gear engagement area. This reduces eddy current losses caused by abrupt changes in flow direction, ensuring that the molten material enters the gear conveying channel smoothly and uniformly, thereby solving the problems of pressure fluctuations and flow instability during material conveying.

[0073] Specifically, the principle of this invention is as follows: The technical principle of constructing a dynamic sealing barrier through the meshing of a driving gear and a driven gear lies in the multiple sealing interfaces formed when the gear teeth penetrate deep into the roots of the other gears during meshing. When the gears rotate, the tooth grooves of the driving gear carry the liquid from the liquid storage area into the meshing area. Subsequently, under the action of meshing pressure, the liquid is squeezed towards the discharge pipe. The synchronous reverse rotation of the driven gear ensures that the meshing area always maintains a continuous liquid pushing channel. When the gears stop rotating, the tooth surfaces of the driving gear and the driven gear are tightly fitted to form a physical barrier. Since the meshing depth reaches 60% to 80% of the tooth height, the effective sealing length of the meshing interface is sufficient to resist the gravity pressure and residual pressure of the liquid. The meshing clearance is controlled within the range of 5% to 15% of the gear module, which avoids tooth surface compression and jamming caused by thermal expansion and prevents liquid leakage caused by excessive clearance. This dynamic and static dual sealing mechanism enables both flow control accuracy and instantaneous cutoff performance to be achieved simultaneously.

[0074] The following provides a specific embodiment 1 of the present invention, and the specific implementation of each step in this embodiment 1 is described in detail below.

[0075] The dual-gear precision control component for the discharge port of a particulate material 3D printer of this invention mainly consists of a housing, a feeding component, and a flow control component. The housing encloses the feeding component and the flow control component, forming a closed working space. The top of the feeding component is connected to the output shaft of the 3D printer's power system via a coupling. The flow control component is located at the bottom of the feeding component and achieves precise control of liquid flow through the meshing of the driving gear and the driven gear. The housing is divided into two parts: a screw guide heating shell and a liquid sealing shell. The screw guide heating shell is made of aluminum alloy and has a cylindrical structure with a wall thickness of 6mm. Eight longitudinal heat dissipation ribs are evenly distributed along the axial direction on the outer wall surface, with a spacing of 12mm between adjacent heat dissipation ribs. The thickness of the heat dissipation ribs is 3mm, and the height of the heat dissipation ribs is calculated based on the outer diameter of the screw guide heating shell. A spiral heating channel is formed between the inner wall of the screw guide heating shell and the outer spiral surface of the rotating screw of the feeding assembly. As the particulate material passes through this channel, it is gradually melted and transformed into a liquid state by the heat transferred from the shell. The liquid sealing shell is located at the bottom of the shell and has a flat cylindrical cavity structure. The inner cavity height is 28mm, and the inner cavity diameter is designed to be 78mm based on the sum of the addendum circles of the driving and driven gears. The wall thickness is 6mm and it is made of stainless steel. The liquid sealing shell and the screw guide heating shell are connected by a flange. The outer diameter of the flange is 65mm, which is larger than the outer diameter of the screw guide heating shell (55mm). The flange and the screw guide heating shell are fastened together by eight bolts evenly distributed circumferentially.

[0076] The feeding assembly is a rotary screw with an Archimedean spiral structure, an outer diameter of 32mm, a helix angle of 20°, a pitch of 28mm, and an effective working length of 150mm. The surface of the rotary screw is nitrided to form a thickness of [missing information]. The hardened layer has a spiral groove depth of 7mm and a spiral groove width of 12mm. The top of the rotating screw is connected to the 3D printer's power system via a flexible coupling, and the bottom extends above the liquid storage area, maintaining an 8mm vertical distance between the bottom end face and the top surface of the liquid storage area. The rotational speed of the rotating screw is set to 25 rpm according to the material delivery requirements. At this speed, the residence time of the granular material in the screw guide heating shell is sufficient to ensure complete melting of the material. The spiral groove volume of the rotating screw is calculated based on its geometric parameters to meet the requirements. In the formula The volume of the helical groove within a single pitch. The outer diameter of the rotating screw is set to 32mm. The pitch of the rotating screw is set to 28mm. With the helical groove depth of the rotating screw taken as 7mm, the volume of the helical groove within a single pitch is calculated using this equation. This allows us to determine the single-turn delivery capacity of the rotating screw at the current rotational speed.

[0077] The liquid storage area is located between the feeding assembly and the flow control assembly, forming an annular cavity structure. Its inner diameter is 32mm, matching the bottom diameter of the rotating screw, and its outer diameter is 78mm, tangent to the inner wall of the liquid sealing shell. The height is 12mm. The volume of the liquid storage area satisfies the requirements of the single-meshing conveying volume of the driving and driven gears. In the formula The design volume of the liquid storage area, The single-cycle conveying volume is given by a coefficient k of 20. The driving gear has a tooth depth of 5mm and a tooth width of 20mm. The driven gear has the same tooth depth and tooth width as the driving gear. The effective meshing length is 18mm. Based on these parameters, the single-cycle conveying volume is calculated as follows: Therefore, the design volume of the liquid storage area is This volumetric design ensures the liquid storage area has sufficient buffer capacity to accommodate pressure fluctuations during intermittent gear delivery. The bottom of the liquid storage area features a conical transition guide surface. The top of the transition guide surface connects to the bottom edge of the liquid storage area, and the bottom is tangent to the plane containing the addendum circles of the driving and driven gears, with a cone angle of 60°. The surface of the transition guide surface is precision polished to a surface roughness of 0.5μm. Four spiral guide grooves are evenly distributed circumferentially on the transition guide surface, with a depth of 2mm and a width of 3mm. The spiral angle matches the helix angle of the rotating screw at 20°. The height of the transition guide surface is calculated based on the dimensions of the liquid storage area and the gears, as well as the cone angle, to meet the requirements. In the formula The height of the transition guide surface, The outer diameter of the liquid storage area is set to 78 mm. The gear tip circle diameter is set to 38mm. The cone angle of the transition guide surface is set to 60°, and the height of the transition guide surface is calculated to be 11.5 mm using this equation.

[0078] The flow control assembly includes a driving gear and a driven gear, which mesh with each other and have the same number of teeth (15). The driving gear has a tip circle diameter of 38mm, a root circle diameter of 32mm, and a tooth width of 20mm. The driven gear has identical geometric parameters. Both the driving and driven gears are made of stainless steel and heat-treated to achieve a hardness of 50HRC. The tooth surfaces are precision ground to a surface roughness of 0.3μm. The driving gear teeth have an arc-shaped structure with a convex arc tip (radius of curvature 3mm) and an involute flank surface. The ratio of the base circle radius to the root circle radius is 0.75. The driven gear teeth have the same shape as the driving gear to ensure a tight seal between the meshing gears. The meshing clearance between the tip of the driving gear and the root of the driven gear is determined by the gear module, which is 2.5mm. The meshing clearance meets the following requirements. That is, 0.25mm. The meshing depth between the driving gear and the driven gear is determined based on the tooth height of the gears. With a tooth height of 6mm, the meshing depth meets the following requirements. That is, 4.2mm. The tooth cogging volume of the driving gear is calculated based on the gear's geometric dimensions and meets the following requirements. In the formula The volume of a single tooth groove. The root circle radius of the driving gear is set to 16mm. The addendum circle radius of the driving gear is set to 19 mm. The tooth width of the driving gear is set to 20mm. Assuming the number of teeth on the driving gear is 15, the volume of a single tooth space can be calculated using this equation. .

[0079] The center of the drive gear is fixedly connected to the rotating rod, which is cylindrical with a diameter of 12mm and a length of 65mm. One end of the rotating rod is fixedly connected to the center hole of the drive gear via a keyway connection. The keyway is 20mm long, 4mm wide, and 3mm deep. The other end of the rotating rod is connected to the output shaft of the 3D printer's power system via a flexible coupling. The rotating rod is made of alloy steel and has undergone heat treatment to achieve a surface hardness of 45HRC. Its surface is chrome-plated to form a thickness of [missing information]. The hard coating. The rotating rod passes through the top wall of the liquid sealing shell and is rotatably connected to the liquid sealing shell via a deep groove ball bearing. The inner ring of the bearing is interference-fitted with the rotating rod. The interference fit between the outer ring of the bearing and the bearing housing bore on the top wall of the liquid seal housing is [insert amount here]. The driven gear is fixedly connected to the support rod at its center. The support rod is cylindrical with a diameter of 12mm, the same as the rotating rod, and a length of 40mm. One end of the support rod is fixedly connected to the center hole of the driven gear via a keyway, the keyway being the same size as the keyway on the rotating rod. The other end of the support rod is fixed to the top wall of the liquid-sealed housing. The support rod achieves rotational movement through bearing support, and the bearing structure is the same as that of the bearing on the rotating rod. The axis of the support rod is parallel to the axis of the rotating rod and lies in the same horizontal plane. The center distance between the two axes is calculated based on the gear module and number of teeth and meets the following requirements. In the formula The distance between the center of the support rod and the rotating rod is denoted by m, which is the gear module and is taken as 2.5 mm. The number of teeth on the drive gear is set to 15. With the number of teeth of the driven gear set to 15, the center distance is calculated to be 37.5 mm using this equation.

[0080] A discharge pipe is located at the bottom of the liquid sealing shell and is connected to it. The discharge pipe has a frustum-shaped structure with an upper opening diameter of 10mm, a lower opening diameter of 0.8mm, a taper angle of 20°, and a length of 32mm. The discharge pipe is made of stainless steel, and its inner wall surface has been precision polished to a surface roughness of 0.6μm. The discharge pipe is connected to the bottom of the liquid sealing shell via a threaded connection, with a high-temperature resistant silicone rubber sealing ring at the threaded connection. The sealing ring has a cross-sectional diameter of 2.5mm. The length of the tapered section of the discharge pipe is calculated based on the diameters of the upper and lower ends and the taper angle to meet certain requirements. In the formula The length of the tapered section of the discharge pipe. The diameter of the upper opening of the discharge pipe is set to 10mm. The diameter of the lower opening of the discharge pipe is set to 0.8 mm. With a taper angle of 20°, the calculated length of the tapered section is 12.6 mm. The discharge pipe is located directly below the meshing point of the driving and driven gears. The central axis of the discharge pipe is perpendicular to the line connecting the centers of the driving and driven gears. The geometric center of the upper opening of the discharge pipe is located 5 mm directly below the meshing point of the driving and driven gears. The minimum clearance between the lowest point of the driving gear and the edge of the upper opening of the discharge pipe is 2 mm, and the minimum clearance between the lowest point of the driven gear and the edge of the upper opening of the discharge pipe is also 2 mm.

[0081] The vertical clearance between the root circles of the driving and driven gears and the inner bottom surface of the liquid sealing shell is 4 mm. The vertical clearance between the addendum circle of the driving gear and the inner top surface of the liquid sealing shell is 5 mm, and the vertical clearance between the addendum circle of the driven gear and the inner top surface of the liquid sealing shell is also 5 mm. The radial clearance between the outer surface of the addendum circle of the driving gear and the inner wall of the liquid sealing shell is 2 mm, and the radial clearance between the outer surface of the addendum circle of the driven gear and the inner wall of the liquid sealing shell is 2 mm. The inner cavity height of the liquid sealing shell is calculated based on the addendum circle diameter of the driving gear and meets the following requirements. In the formula The height of the inner cavity of the liquid-sealed shell. With the tip circle diameter of the driving gear taken as 38mm, the inner cavity height is calculated to be 28.5mm using this equation.

[0082] During operation, granular material is fed into the top of the rotating screw through the 3D printer's feed inlet. The power system is activated, driving the screw to rotate at 25 rpm. The granular material is propelled downwards along the spiral channel by the rotating screw and gradually melts under the heating effect of the screw's guide heating shell. The molten liquid material enters the liquid storage area. The annular cavity structure of the liquid storage area provides a buffer space to accommodate pressure fluctuations during intermittent gear feeding. The liquid flows through the transition guide surface to the meshing area of ​​the driving and driven gears. The spiral guide grooves on the transition guide surface continue the pushing action of the rotating screw and reduce eddy current losses during liquid flow. The driving and driven gears rotate in opposite directions. The rotation of the driving gear is powered by a rotating rod, and the driven gear achieves synchronous reverse rotation through meshing with the driving gear. When the rotation speed of the driving gear is 35 rpm, the liquid output flow rate from the discharge pipe is... / s. The meshing position of the driving gear and the driven gear forms a dynamic sealing barrier. Liquid is transported within the gear grooves to the area below the meshing zone and discharged through the discharge pipe. When it is necessary to stop the discharge, the power system stops operating, and the driving gear and the driven gear stop rotating. At this time, the gear meshing position forms a completely sealed physical barrier, blocking the natural flow of liquid under gravity, achieving an instantaneous cutoff function. By adjusting the rotation speed of the power system, the rotational speed of the driving gear and the driven gear can be precisely controlled, thereby achieving precise adjustment of the liquid output flow rate from the discharge pipe, meeting the material delivery requirements of the 3D printer under different printing speeds and printing accuracy requirements.

[0083] This embodiment incorporates a liquid storage zone between the feeding assembly and the flow control assembly. This storage zone has an annular cavity structure, and its volume is proportional to the volume of a single gear engagement. When the coefficient k is controlled within the range of 15-25, the storage zone can effectively absorb the flow difference between continuous screw conveying and intermittent gear conveying, eliminating the impact of pressure pulses on the stability of the output. Simultaneously, a conical transition guide surface is provided at the bottom of the liquid storage zone. The cone angle of this guide surface is set between 45° and 70°, and a spiral guide groove is provided on its surface, with the spiral angle matching the helix angle of the rotating screw. This continues the feeding action of the screw and guides the liquid tangentially into the gear meshing area, avoiding splashing and eddy current losses caused by the liquid falling vertically. This ensures that the entire process from solid melting to liquid conveying and then to precise extrusion remains continuous and stable, improving the controllability of material flow and the consistency of printing quality during 3D printing.

[0084] The following is a specific application scenario example 2: The research team used the dual-gear precision control component of this invention when performing a high-precision medical device 3D printing task. This task required a printing accuracy of 0.05mm and a material delivery flow rate that was within a certain range. / s~ Precise control was achieved within a range of / s. The research team first determined the heating temperature of the screw guide heating shell to be 185℃ based on the characteristics of medical-grade polylactic acid (PLA) material. This temperature ensures that the PLA particles fully melt within the spiral channel without thermal degradation. The team installed a driving gear and a driven gear with 15 teeth, a tip circle diameter of 38mm, and a tooth width of 20mm into the liquid-sealed shell. Measuring tools confirmed that the center distance between the driving and driven gears was 37.5mm, the meshing clearance was 0.25mm, and the meshing depth was 4.2mm. A pressure sensor was installed in the liquid storage area to monitor pressure fluctuations in real time, with the sampling frequency set to 150Hz. During assembly, the team paid special attention to the gap between the discharge pipe and the lowest point of the driving and driven gears. Using precision measuring tools, this gap was adjusted to 2mm to ensure that the liquid flows evenly into the discharge pipe from the meshing area and that the gears do not interfere with the discharge pipe during rotation. The research team set the rotational speed of the screw to 20 rpm and the speed of the drive gear to 30 rpm. At this point, the system output flow rate stabilized at... / s. During the printing process, the research team adjusted the speed of the drive gear in real time according to the complexity of the printing path using the speed regulation function of the power system. When printing straight sections, the speed was increased to 45 rpm to achieve the required output flow rate. / s, When printing fine curve segments, reduce the rotation speed to 15 rpm to reduce the output flow rate to / s. The research team recorded pressure fluctuation data for 8 consecutive hours of work, as shown in Table 1.

[0085] Table 1. Pressure fluctuation data of liquid storage area at different time periods

[0086]

[0087] Table 1 shows that the peak pressure fluctuation in the liquid storage area remained below 0.032 MPa, lower than the set threshold of 0.03 MPa. The material residence time was between 12.3 s and 13.1 s, meeting the allowable range of 30 s to 60 s for materials with good thermal stability. After printing, the research team tested the dimensional accuracy of the medical device model and found that the deviation of all key dimensions was controlled within 0.04 mm, and the surface quality was good with no obvious layering or porosity defects. The research team conducted wear tests on the meshing surfaces of the drive and driven gears. The tooth surface roughness increased from the initial 0.3 μm to 0.35 μm, and the minimal wear proved that the hardness of the gear material and the surface treatment process met the requirements for long-term use. The research team also tested the system's instantaneous cutoff function. When the drive and driven gears stopped rotating, the discharge pipe completely stopped discharging within 3 seconds. The physical barrier formed by the liquid at the gear meshing position effectively blocked the natural flow under gravity, avoiding the dripping phenomenon commonly seen in traditional extrusion 3D printers when discharging stops. In traditional single-screw extruders, when the discharge port stops, the liquid continues to flow out under gravity due to the gap between the screw and the heating chamber. The dripping time after the discharge stops is usually between 8 and 15 seconds. However, this invention shortens the dripping time to less than 3 seconds by forming a sealing barrier through double gear meshing, improving printing accuracy by about 15% and avoiding excess material accumulation on the surface of the printed parts.

[0088] Example 3 provides a specific application scenario: The research team used the dual-gear precision control component of this invention in a batch 3D printing task of engineering plastic parts. This task used nylon material for printing and required a single continuous printing time of over 24 hours. Based on the melting temperature range of nylon material, the research team set the heating temperature of the screw guide heating shell to 240°C. This temperature ensures that the nylon particles completely melt within the spiral channel, forming a highly fluid liquid. The research team selected a driving gear and a driven gear with 18 teeth, a tip circle diameter of 45mm, and a tooth width of 25mm. This configuration, compared to Example 1, has a larger single-meshing conveying volume, meeting the high-flow-rate requirements of engineering part printing. The research team calculated the optimal meshing clearance as 0.3mm and the optimal meshing depth as 5.4mm using a game theory model. Based on the liquid sealing shell inner cavity height of 33mm, the number of gear teeth of 18, the gear module of 3mm, and the center distance of 54mm, the optimal tooth width was calculated to be 24mm. The research team used a ratio coefficient k of 22 in the design of the liquid storage area volume, based on the single-cycle conveying volume. The calculated design volume of the liquid storage area is: This volumetric design ensures buffering capacity while avoiding thermal degradation caused by excessive material residence time. The research team set the rotational screw speed to 35 rpm and the drive gear speed to 50 rpm, at which point the system output flow rate reached... The system meets the rapid printing needs of large-size engineering parts. During 24-hour continuous printing, the research team recorded system operating parameters every 4 hours, including output flow rate, gear speed, liquid storage area pressure, and discharge pipe temperature. Data showed that the system operated stably, with fluctuations in all parameters within 5%. The research team paid particular attention to gear wear. After 24 hours of continuous operation, the driving and driven gears were disassembled and inspected. They found that the tooth surface roughness increased from the initial 0.3 μm to 0.42 μm, and the meshing clearance increased from 0.3 mm to 0.31 mm. These changes were far less than the design allowable range, proving that the gears, after heat treatment and surface grinding, have excellent wear resistance. The research team also conducted fluid dynamics analysis on the conical section of the discharge pipe. By installing a micro-flow velocity sensor inside the discharge pipe, they measured the liquid velocity distribution at different locations within the conical section. The results showed that the liquid velocity increased from the upper end of the discharge pipe... Smooth transition to the lower end No obvious eddies or turbulence were observed during the flow process, verifying the rationality of the calculation equations for the 20° taper angle of the discharge pipe and the length of the tapered section. After printing, the research team tested the mechanical properties of the engineering components, finding a tensile strength of 62 MPa, a flexural strength of 85 MPa, and an impact strength of [missing information]. All indicators meet the requirements of engineering applications. Traditional gear pump discharge ports experience a gradual increase in liquid leakage during long-term continuous operation due to the large gap between the gears and the pump body. Typically, after 12 hours of operation, the leakage rate accounts for 3% to 5% of the total conveying volume. However, this invention controls the leakage rate to less than 1% by optimizing the meshing clearance and meshing depth, improving material utilization by approximately 18% and significantly reducing material waste.

[0089] Example 4 provides a specific application scenario: The research team used the dual-gear precision control component of this invention in a multi-material hybrid 3D printing experiment. This experiment required frequent switching between different colors and properties of thermoplastic elastomer materials during the printing process. Based on the processing temperature range of the thermoplastic elastomer material, the research team set the heating temperature of the screw guide heating shell to 210℃. This temperature ensures sufficient material melting while avoiding excessive softening and resulting in excessive fluidity. The research team selected a driving gear and a driven gear with 12 teeth, a tooth tip circle diameter of 30mm, and a tooth width of 15mm. Compared to Examples 1 and 2, this configuration has a smaller single-meshing transport volume and a faster response speed, making it particularly suitable for multi-material printing tasks requiring frequent start-stop and flow rate adjustments. Before the experiment, the research team specially designed the gear tooth shape, adopting a pointed tooth structure with a tooth tip angle of 75° and an angle of 30° between the tooth side and the radial direction of the gear. This tooth shape has a stronger shearing effect than curved teeth, enabling rapid clearing of residual material in the tooth grooves during material switching. The research team added a heating device to the inner bottom surface of the liquid-sealed shell to maintain the temperature of the liquid-sealed shell at 200℃, preventing the liquid from solidifying below the gears and blocking the discharge channel. The team designed a material switching procedure: when material switching is required, the rotation speed of the drive gear is first reduced from its current value to 5 rpm and maintained for 10 seconds to empty the liquid storage area and the original material in the gear teeth. Then, the rotation of the screw and drive gear is stopped, and the residual material in the discharge pipe is blown out by a reverse airflow. Finally, the new material conveying procedure is started. The team monitored the color change of the material output from the discharge pipe using optical sensors. Experimental results showed that the time from stopping the conveying of old material to outputting pure new material was 18 seconds, and the length of the material color transition section was controlled within 15 mm. The team recorded key parameters during 10 material switching processes, as shown in Table 2.

[0090] Table 2 Key Parameter Records for Material Switching Process

[0091]

[0092] Table 2 shows that the material evacuation time and the arrival time of new material are stable, the length of the color mixing transition section is consistently controlled within 16 mm, and the tooth groove cleanliness remains above 95%, demonstrating the significant cleaning effect of the pointed tooth structure on residual materials. After completing the multi-material printing experiment, the research team analyzed the interface bonding quality of the printed parts. Using scanning electron microscopy to observe the interface structure between different materials, they found no obvious gaps or cracks at the interface, and the bonding strength between the materials reached 82% of the strength of a single material. The research team also tested the system's performance under rapid start-stop conditions, step-changing the rotational speed of the drive gear between 5 rpm and 60 rpm, and observing the response time and stability of the output flow rate. The results showed that the output flow rate reached the target value within 2 seconds after the speed change, and the flow rate fluctuation after stabilization was less than 3%. Traditional multi-material 3D printing systems typically use multiple independent extruders to deliver different materials. When switching materials, the print head needs to be moved to the discharge port of different extruders, and the switching time is usually between 60s and 120s. However, this invention shortens the material switching time to 18s by using a single dual-gear control component combined with a rapid evacuation and cleaning procedure, improving the switching efficiency by about 17%, significantly improving the production efficiency of multi-material printing and reducing material waste.

[0093] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-gear precision control component for the discharge port of a particulate material 3D printer, comprising a housing, a feeding component, and a flow control component, wherein the housing is located outside the feeding component and the flow control component, the top of the feeding component is connected to the power system of the 3D printer, and the flow control component is disposed at the bottom of the feeding component, characterized in that, The flow control component includes a drive gear and a driven gear. The drive gear and the driven gear are meshed together. The center of the drive gear is fixedly connected to the rotating rod, and the center of the driven gear is fixedly connected to the support rod. The meshing of the drive gear and the driven gear seals the liquid conveyed by the pusher component between the pusher component and the flow control component. The rotation of the rotating rod and the support rod drives the liquid to be conveyed to the bottom of the flow control component. When the drive gear and the driven gear stop rotating, the meshing position of the drive gear and the driven gear forms a completely sealed physical barrier to block the natural flow of the liquid under the action of gravity.

2. The dual-gear precision control assembly for the discharge port of a particulate material type 3D printer according to claim 1, characterized in that, The housing includes a screw guide heating housing and a liquid sealing housing. The screw guide heating housing is sleeved on the outside of the pusher assembly, and the liquid sealing housing is located at the bottom of the housing and covers the middle position between the pusher assembly and the flow control assembly, as well as the flow control assembly.

3. The dual-gear precision control assembly for the discharge port of a particulate material type 3D printer according to claim 2, characterized in that, The screw guide heating shell has a cylindrical structure, and a spiral heating channel is formed between the inner wall surface of the screw guide heating shell and the outer spiral surface of the pusher assembly.

4. The dual-gear precision control assembly for the discharge port of a particulate material type 3D printer according to claim 3, characterized in that, The screw guide heating shell is made of aluminum alloy. The outer wall of the screw guide heating shell is provided with multiple longitudinal heat dissipation ribs, which are evenly distributed along the axial direction of the screw guide heating shell.

5. The dual-gear precision control assembly for the discharge port of a particulate material type 3D printer according to claim 4, characterized in that, The liquid sealing shell has a flat cylindrical cavity structure, and the inner diameter of the liquid sealing shell matches the sum of the tip circle diameters of the driving gear and the driven gear.

6. The dual-gear precision control assembly for the discharge port of a particulate material type 3D printer according to claim 5, characterized in that, A liquid storage area is provided between the feeding component and the flow control component, and the liquid storage area has an annular cavity structure.

7. The dual-gear precision control assembly for the discharge port of a particulate material type 3D printer according to claim 6, characterized in that, The bottom of the liquid sealing shell is provided with a discharge pipe, which is connected to the liquid sealing shell. The discharge pipe has a frustum-shaped structure.

8. The dual-gear precision control assembly for the discharge port of a particulate material type 3D printer according to claim 7, characterized in that, The driving gear and the driven gear have the same number of teeth. The driving gear has 12 to 18 teeth, and the tip circle diameter of the driven gear is equal to that of the driving gear.

9. A design method for a dual-gear precision control component for the discharge port of a particulate material 3D printer, characterized in that, This invention relates to a dual-gear precision control component for the discharge port of a particulate material 3D printer as described in any one of claims 1 to 8. It determines the basic parameters of the driving and driven gears based on the material delivery flow requirements of the 3D printer, collects multiple sets of liquid delivery flow data for the dual-gear component at different speeds, and establishes a correlation dataset between gear parameters and delivery volume. Using the single-meshing delivery volume as a benchmark, it designs the volume of the liquid storage area and determines the optimal range of the ratio coefficient. It establishes an upper-level game theory model with optimal sealing performance as the objective and a lower-level game theory model with maximum delivery efficiency as the objective. The gear meshing contact area is used as a coupling term for correlation. The upper-level game theory model is used to calculate the optimal meshing clearance and optimal meshing depth, and the lower-level game theory model is used to calculate the optimal tooth width and determine the range of coefficient values ​​in the tooth width calculation.

10. The design method according to claim 9, characterized in that, The associated dataset is established by pairing and recording the tooth groove depth, tooth width, tooth root circle radius, tooth tip circle radius, and corresponding single meshing conveying volume under different gear parameter combinations, forming a multidimensional data table containing gear geometric parameters and conveying performance parameters.

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