Compact extruder and extrusion method thereof

Abstract

The invention belongs to the technical field of extruders, and relates to a compact extruder and an extrusion method thereof. Comprising a speed reducing mechanism, an operating mechanism, a main extrusion wheel structure, an extruder frame and a driving motor, the driving motor is connected with the reducing mechanism; the main extrusion wheel is connected with the speed reducing mechanism through the adapter; the operating mechanism comprises two driven extrusion wheels, a balance beam type frame, a handle frame and an adjusting mechanism; the driven extrusion wheel is installed on the balance beam type frame, the balance beam type frame is installed on the handle frame, and the adjusting mechanism is installed on the outer side of the handle frame. The two driven extrusion wheels are meshed with the main extrusion wheel; u-shaped consumable occlusal surfaces are arranged in the middles of the outer circular surfaces of the middles of the main extrusion wheel and the two driven extrusion wheels, and bevel gears are symmetrically designed on the two sides of the U-shaped consumable occlusal surfaces; and a wire material is clamped between the U-shaped consumable occlusal surfaces of the main extrusion wheel and the two driven extrusion wheels. The problems of limited extrusion force, slipping caused by insufficient contact area, limited equipment miniaturization caused by volume increase and the like are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of extruders, and in particular relates to a compact extruder and an extrusion method thereof. Background Art

[0002] With the continuous advancement of computer numerical control technology, the application of 3D printing technology is becoming increasingly widespread. Fused Deposition Modeling (FDM) printing technology is experiencing growing demand for processing high-temperature-resistant, high-hardness materials. In the medical and high-end manufacturing industries, the use of FDM technology to print high-performance engineering plastics (such as PPA and PEEK) has become a trend. These materials offer excellent high-temperature resistance, mechanical strength, and chemical stability, making them suitable for manufacturing precision medical devices (such as surgical guides and implant prototypes), aerospace components (such as heat-resistant stents and lightweight structural parts), and functional end-use parts in the automotive industry.

[0003] In FDM printing, an extruder is typically used to feed filaments into the print head. Its performance directly determines the key factors of printing quality, including material feeding stability, extrusion accuracy, and interlayer bonding strength.

[0004] Currently, FDM printer extruders generally use a combination of a gear reduction mechanism (reduction ratio 4-12) and an ordinary stepper motor, which has the following technical bottlenecks: The extrusion of high-hardness consumables (such as PEEK) requires a large driving force. Under the traditional reduction ratio, the stepper motor output torque is insufficient, and the extrusion flow rate is too small, which can easily lead to poor inter-layer bonding strength or printing interruption. The contact area between the passive extrusion wheel of the wire feeder and the consumables is limited. Increasing the pre-pressure can alleviate slippage, but it will cause a sharp increase in the motor load, leading to overheating, motor stalling and other faults. Simply increasing the motor power or the size of the extrusion wheel to meet the extrusion force requirements will cause the extruder volume to expand, seriously restricting the compact design of the printer. Summary of the Invention

[0005] The purpose of the present invention is to provide a compact extruder and an extrusion method thereof, which solve the problems in the prior art such as limited extrusion force due to insufficient reduction ratio, slippage caused by insufficient contact area, and limited equipment miniaturization due to increased volume.

[0006] The present invention is achieved through the following technical solutions: A compact extruder includes a speed reduction mechanism, an operating mechanism, a main extrusion wheel structure, an extruder frame and a drive motor; The speed reduction mechanism and the main extrusion wheel structure are installed in the extruder frame, and the operating mechanism is installed on one side of the main extrusion wheel structure; the output shaft of the drive motor is connected to the speed reduction mechanism; The main extrusion wheel structure includes a main extrusion wheel and a connector, and the main extrusion wheel is connected to the speed reduction mechanism through the connector; The operating mechanism includes a passive extrusion wheel A, a passive extrusion wheel B, a balance beam frame, a handle frame and an adjustment mechanism; the passive extrusion wheel A and the passive extrusion wheel B are installed on the balance beam frame, the balance beam frame is installed on the handle frame, and the adjustment mechanism is installed on the outside of the handle frame; Both the passive extrusion wheel A and the passive extrusion wheel B are meshed with the main extrusion wheel; the middle of the outer circular surface of the main extrusion wheel and the two passive extrusion wheels are U-shaped consumables biting surfaces, the surface of the U-shaped consumables biting surface is covered with rough metal horizontal stripes, and the two sides of the U-shaped consumables biting surface are symmetrically designed as helical gears; the filament is clamped between the U-shaped consumables biting surfaces of the main extrusion wheel and the two passive extrusion wheels, and is stably output under the action of rotating extrusion.

[0007] Furthermore, the reduction mechanism includes a housing A and a housing B, wherein a gear reduction structure and a cycloid reduction structure are installed in the housing A and the housing B; The gear reduction structure includes a motor gear and three crankshaft gears mounted on the output shaft of the drive motor. The motor gear and the three crankshaft gears are meshed and linked to perform a first-stage reduction; The cycloid reduction structure includes an output flange A, an output flange B, a crankshaft, a cycloid disk A, and a cycloid disk B. The crankshaft is linked to the crankshaft gear. The crankshaft is linked to the cycloid disk A and the cycloid disk B to perform secondary reduction. The motor gear and three crankshaft gears are installed in the output flange A, the output flange A is installed in the housing A, and the output flange B is installed in the housing B; the crankshaft passes through the crankshaft gear, cycloid disk A and cycloid disk B in sequence, the cycloid disk A is installed in the housing A, and the cycloid disk B is installed in the housing B; Flange bearings are used on all rotating contact surfaces of the crankshaft.

[0008] Furthermore, the output flange A is mounted in the housing A via a thin-walled bearing; the output flange B is mounted in the housing B via another thin-walled bearing; and the adapter bearing is mounted in the adapter bearing mounting frame.

[0009] Furthermore, housing A and housing B are machined with needle roller holes, in which a plurality of needle rollers are installed; Bearing rings are provided between the thin-walled bearing and the housing A, and between the thin-walled bearing and the housing B; The number of teeth on the cycloid disc is one less than the number of needle rollers.

[0010] Furthermore, a limiting groove for installing a retaining ring is processed at the end of the crankshaft, and a retaining ring is installed on the limiting groove of each crankshaft, and the retaining ring is arranged on the outside of the crankshaft gear.

[0011] Furthermore, a D-shaped hole is processed in the center of the crankshaft gear, and the end of the crankshaft close to the crankshaft gear is processed into a D-shaped shaft. The D-shaped shaft is located inside the limiting groove, and the D-shaped shaft of the crankshaft passes through the D-shaped hole of the crankshaft gear.

[0012] Furthermore, the handle frame is prefabricated with mounting hole A, upper mounting hole, and lower mounting hole; The adjustment mechanism includes a thumb screw and a spring. The thumb screw is installed in the mounting hole A. The spring is wound around the rod of the thumb screw. A gasket is installed on the side of the spring that contacts the handle frame. The balance beam frame is rotatably connected to the upper mounting hole of the handle frame through a balance frame fixing pin shaft; the handle fixing pin shaft passes through the lower mounting hole of the handle frame and is connected to the extruder frame.

[0013] Furthermore, the extruder frame includes a coupling bearing mounting frame, an extruder feed pressure plate and a motor frame; the reduction mechanism is installed in the motor frame, and the drive motor is installed on one side of the motor frame; the main extrusion wheel structure is installed in the extruder frame; a feeding hole is prefabricated on the extruder feed pressure plate, and the extruder feed pressure plate is connected to the operating mechanism.

[0014] The present invention also discloses an extrusion method of the compact extruder, comprising the following steps: After the driving motor drives the reduction gear structure to reduce speed, the reduction gear structure transmits power to the adapter, and the adapter transmits power to the main extrusion wheel, and the main extrusion wheel starts to rotate; The printing filament passes through the feed port on the extruder frame and enters the U-shaped filament bite surface of the two passive extrusion wheels and the main extrusion wheel. Under the rotation and extrusion of the main extrusion wheel and the two passive extrusion wheels, it is extruded through the discharge port to complete the extrusion operation; During extrusion, the balance beam frame rotates around the handle frame, so that the U-shaped filament biting surfaces of the two passive extrusion wheels are close to the printing filament; When a larger extrusion force is required or the hardness of the filament itself is relatively high, the pre-pressure applied to the two passive extrusion wheels is increased through the adjustment mechanism to increase the extrusion force of the extruder; when a smaller extrusion force is required or the hardness of the filament itself is relatively low, the pre-pressure applied to the two passive extrusion wheels is reduced through the adjustment mechanism.

[0015] Furthermore, the deceleration process of the deceleration structure is as follows: The drive motor is energized to drive the motor gear to rotate, and the motor gear meshes with the three crankshaft gears and drives them to rotate, completing the first stage of reduction; The three crankshaft gears all receive power and evenly transmit the power from the drive motor to the three crankshafts. The crankshaft rotation causes the cycloid disks A and B to revolve eccentrically, and the cycloid disks A and B to move eccentrically with opposite phases. The number of teeth on the cycloid disk is one less than that on the needle rollers. The cycloid disk rotates in the opposite direction by one tooth pitch for each revolution. The combined motion of revolution and rotation is transmitted to the output flange A and output flange B through the crankshaft and flange bearings, completing the second stage of deceleration.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention discloses a compact extruder, in which a passive extrusion wheel adopts two gears, and the main extrusion wheel and the passive extrusion wheel adopt mirror-symmetrical helical gears on both sides, an extrusion wheel with a U-shaped consumable material engaging surface is provided in the middle, and an innovative design of a double passive extrusion wheel with automatic position adjustment (which can balance the pressure of the two passive extrusion wheels on the consumable material), the two small passive extrusion wheels press the consumable material on the U-shaped consumable material engaging surface of the main extrusion wheel, greatly increasing the contact area between the extrusion wheel and the consumable material, and avoiding the problem of consumable material slipping; the two symmetrical helical gears are designed to effectively offset the axial force, and the double helix structure ensures that at least two pairs of teeth are engaged at the same time, reducing torque fluctuation, and solving the problem of eccentric wear of the passive gears of traditional extruders.

[0017] The passive extrusion wheel of a traditional extruder adopts a single-sided gear meshing transmission (the other side of the extrusion wheel is the consumables meshing surface). During operation, the consumables meshing surface contacts the consumables, and the spring applies pressure to the passive extrusion wheel, most of which is applied to the consumables meshing surface. This will cause the bearing on the side of the consumables meshing surface to bear a radial force much greater than the bearing on the gear side. In long-term operation, the aging of the bearings on both sides will be inconsistent, resulting in the problem of too short a bearing life on the side of the consumables meshing surface. The passive extrusion wheel of the present invention is designed with helical gears on both sides of the U-shaped consumables meshing surface. The U-shaped consumables meshing surface that bears the main pressure is designed in the middle of the passive extrusion wheel, and the bearings are symmetrically installed in the bearing mounting holes on both sides. This design balances the pressure on the bearings on both sides and extends the life of the bearings on both sides. The helical gears on both sides of the extrusion wheel balance the axial force generated by the meshing of the helical teeth on both sides, avoiding the problem of excessive axial force on one side of the bearing caused by the use of single-sided helical gears in traditional extrusion wheels, thereby extending the service life of the bearings.

[0018] The balance beam frame can be rotated to a certain angle, so that the U-shaped grooves of the two passive extrusion wheels can be close to the printing filament, and the two passive extrusion wheels have a certain adjustment ability, which can balance the load of the two passive extrusion wheels and avoid the problem of one passive extrusion wheel being overloaded and the other passive extrusion wheel being underloaded.

[0019] The use of a balanced beam frame to mount two passive extrusion wheels not only increases the contact area but also automatically balances the load between the two extrusion wheels. Compared with the traditional single extrusion wheel structure, this design significantly improves extrusion stability and component life.

[0020] When the extruder of the present invention outputs the same extrusion force, the pre-pressure provided by the regulating mechanism is smaller, the bearing load on the passive extrusion wheel is lower, and the service life of the entire extruder is longer.

[0021] The compact extruder of the present invention achieves five breakthroughs that traditional extruders cannot achieve, namely, high extrusion force, low preload, long life, compact structure and easy maintenance, through multiple collaborative innovative designs.

[0022] Furthermore, the reduction mechanism utilizes a first-stage gear reduction and a second-stage cycloid reduction mechanism, achieving a reduction ratio significantly higher than that of traditional extruder reducers and delivering greater extrusion force. This makes the reducer more compact, achieving a higher reduction ratio for the same volume compared to traditional extruder reduction mechanisms, and also achieving greater extrusion force for the same volume compared to traditional extruders. The first-stage gear reduction mechanism evenly distributes the input torque across the three crankshafts, reducing the load on each crankshaft and avoiding the stress concentration associated with traditional single-gear transmissions. Compared to traditional gear reducers, the reducer designed using the cycloid reduction principle is more compact (particularly with a shorter axial length) for the same reduction ratio. This compact extruder reduces the size of the 3D printer tool head and improves the 3D printer's workspace utilization. Flange bearings are used on all rotating contact surfaces of the crankshaft. These flange bearings cooperate with the reducer housing to provide axial positioning for the crankshaft. Washers are used to elevate the inner bearing ring to prevent friction between the outer ring and other mechanical components, ensuring smooth rotation.

[0023] Furthermore, the main extrusion wheel adopts a three-point support structure consisting of large-diameter thin-walled bearings and adapter bearings, significantly improving its load-bearing capacity and service life. Using large-diameter thin-walled bearings as bearings for the output flange significantly improves space utilization and further shortens the axial length of the reducer. The crankshaft gear can be placed within output flange A, and the hexagonal coupler joint can be placed within output flange A. Output flange A, output flange B, and the hexagonal coupler can be considered the axis of the main extrusion wheel, equivalent to two large-diameter thin-walled bearings and adapter bearings on a single axis. The thin-walled bearings not only support the output flange of the reducer but can also withstand radial loads from the main extrusion wheel. The large thin-walled bearings can disperse the load with the help of the large-diameter bearings, reducing contact stress and thus extending the bearing life.

[0024] Furthermore, the reducer housing A and the reducer housing B have multiple functions. They can serve as bearing seats for thin-walled bearings and can also form the outer ring needle teeth of the cycloid reducer together with the needle rollers. Using finished needle rollers instead of directly processing the housing into a needle tooth shape greatly reduces the processing difficulty of the housing. Using needle rollers installed on the housing as the outer ring needle teeth of the cycloid reducer has the following advantages: the needle rollers are easy to process and easy to obtain. The needle rollers are made of bearing steel, which is more durable than the stainless steel or aluminum alloy material of the housing. In addition, the needle rollers are installed on the reducer housing and are easy to replace if damaged, without replacing the entire housing.

[0025] The bearing washer plays multiple roles: (1) It reduces the difficulty of machining the reducer housing. If a step ring of the same shape is machined on the reducer housing, the manufacturing difficulty of the reducer housing will be greatly increased; (2) It supports the outer ring of the thin-walled bearing to avoid friction between the inner ring of the bearing and the reducer housing; (3) It axially limits the needle roller installed in the needle roller hole of the reducer housing to prevent the needle roller from slipping out of the hole.

[0026] Furthermore, the retaining spring limits the crankshaft gear axially to prevent the crankshaft gear from slipping during frequent starting, stopping and reversing operations, thereby improving the stability of the reducer.

[0027] Furthermore, the crankshaft and crankshaft gear adopt a D-shaped hole transition fit. Compared with the circular hole interference fit, the advantage is that the crankshaft gear can be replaced and easy to maintain. At the same time, the D-shaped hole fit is impact-resistant and more suitable for the frequent start-stop and reversing conditions of 3D printing extruders.

[0028] Furthermore, the adjustment mechanism can improve the extruder's adaptability to consumables of different hardnesses. When a greater extrusion force is required or the consumable filament itself is relatively hard, the thumbscrew can be rotated to increase the compression of the spring, thereby increasing the pre-pressure applied to the two passive extrusion wheels, increasing the friction between the extrusion wheels and the consumable, and increasing the extrusion force of the extruder. When a smaller extrusion force is required or the consumable filament itself is relatively hard, the thumbscrew can be rotated in the opposite direction to reduce the compression of the spring, thereby reducing the pre-pressure applied to the two passive extrusion wheels, thereby avoiding the problem of consumable deformation of softer consumables due to excessive pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the external shape of a compact extruder of the present invention; Figure 2 Schematic diagram of the structure of the meshing of the main extrusion wheel and the passive extrusion wheel; Figure 3 for Figure 1 Exploded diagram; Figure 4 It is a cross-sectional view of the reduction mechanism; Figure 5 This is the exploded diagram of the reduction mechanism; Figure 6 The exploded view of the operating mechanism; Figure 7 Schematic diagram of the structure of the main extrusion wheel.

[0030] Among them, 1. filament; 2. deceleration mechanism; 3. operating mechanism; 4. main extrusion wheel structure; 5. extruder frame; 6. drive motor; 211, crankshaft gear; 212, motor gear; 213, retaining spring; 221. Thin-walled bearing; 222. Bearing backing ring; 2231. Housing A; 2232. Housing B; 224. Needle roller; 2251. Cycloid disk A; 2252. Cycloid disk B; 2261. Output flange A; 2262. Output flange B; 2271. Flange bearing; 2272. Crankshaft; 2273. Gasket; 228. Flat-head screw; 311. Passive extrusion wheel A; 312. Passive extrusion wheel B; 33. Passive extrusion wheel bearing; 341. Passive extrusion wheel fixing pin; 342. Balance frame fixing pin; 343. Handle fixing pin; 35. Thumb screw; 36. Spring; 37. Washer; 38. Handle frame; 39. Balance beam frame; 41. Main extrusion wheel; 42. Adapter; 43. Adapter bearing; 411, spline hole; 412, U-shaped consumables occlusal surface; 413, helical gear; 414, screw mounting hole; 51. Adapter bearing mounting bracket; 52. Extruder feed plate; 53. Motor frame. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clear, the following is a further detailed description with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0032] The components described and illustrated in the drawings and embodiments of the present invention may be arranged and designed in a variety of different configurations. Therefore, the detailed description of the embodiments of the present invention provided in the following drawings is not intended to limit the scope of the claimed invention, but merely represents a selected embodiment of the present invention. All other embodiments derived by those skilled in the art based on the drawings and embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention.

[0033] It should be noted that the terms "comprises", "includes" or any other variations are intended to cover non-exclusive inclusion, so that a process, element, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to the process, element, method, article or apparatus.

[0034] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0035] like Figure 1 and Figure 3 As shown, the present invention discloses a compact extruder, including a speed reduction mechanism 2, an operating mechanism 3, a main extrusion wheel structure 4, an extruder frame 5 and a drive motor 6; the speed reduction mechanism 2 and the main extrusion wheel structure 4 are installed in the extruder frame 5, and the operating mechanism 3 is installed on one side of the main extrusion wheel structure 4.

[0036] The extruder frame 5 includes an adapter bearing mounting bracket 51, an extruder feed platen 52, and a motor frame 53. The reduction gear 2 is mounted in the motor frame 53, and the drive motor 6 is mounted on one side of the motor frame 53. The main extrusion wheel structure 4 is mounted in the extruder frame 5. The extruder feed platen 52 has a prefabricated feed hole and is connected to the operating mechanism 3.

[0037] like Figure 3 As shown, the main extrusion wheel structure 4 includes a main extrusion wheel 41 , an adapter 42 and an adapter bearing 43 .

[0038] The reduction mechanism 2 is locked to the drive motor 6 by four flat-head bolts passing through the motor frame 53; the adapter 42 is fixed to the reduction mechanism 2 by three cup-head bolts, the main extrusion wheel 41 is tightly assembled to the knurling of the output shaft of the adapter 42 by extrusion, and the adapter bearing 43 is installed to the non-knurled part of the output optical axis of the adapter 42; the adapter bearing mounting frame 51 is fixed to the motor frame 53 by four cup-head fixing screws passing through the extruder feed pressure plate 52; the operating mechanism 3 is connected to the extruder feed pressure plate 52.

[0039] See also Figure 4 and Figure 5 , which shows a schematic structural diagram of the speed reduction mechanism 2 designed by the present invention and adapted to the working conditions of the 3D printing extruder.

[0040] like Figure 5 The deceleration mechanism 2 is shown in an exploded view. The deceleration mechanism 2 includes a housing A2231 and a housing B2232. A gear deceleration structure and a cycloid deceleration structure are installed in the housing A2231 and the housing B2232.

[0041] The gear reduction structure includes a motor gear 212 and three crankshaft gears 211 mounted on the output shaft of the drive motor 6. The motor gear 212 is meshed with the three crankshaft gears 211 to perform a first-stage reduction.

[0042] The cycloid reduction structure includes an output flange A2261 and an oppositely mounted output flange B2262, a crankshaft 2272, a cycloid disc A2251, and a cycloid disc B2252. The two flanges are synchronously linked, and the crankshaft 2272 is linked to the crankshaft gear 211. The crankshaft 2272 is linked to the cycloid disc A2251 and the cycloid disc B2252 to perform a two-stage reduction.

[0043] The motor gear 212 and the three crankshaft gears 211 are installed in the output flange A2261. The output flange A2261 is installed in the housing A2231 through a thin-walled bearing 221. A bearing washer 222 is placed between the thin-walled bearing 221 and the housing A2231. Similarly, the output flange B2261 is installed in the housing B2232 through another thin-walled bearing 221. A bearing washer 222 is also installed between the thin-walled bearing 221 and the housing B2232. The bearing washer 22 serves to prevent friction between the inner ring of the bearing and the housing of the reduction mechanism.

[0044] The crankshaft 2272 passes through the crankshaft gear 211, the cycloid disk A2251 and the cycloid disk B2252. The cycloid disk A2251 is installed in the housing A, and the cycloid disk B2252 is installed in the housing B. A D-shaped hole is processed in the center of the crankshaft gear 211, and a limiting groove for installing the retaining spring 213 is processed at the end of the crankshaft 2272. A retaining spring 213 is installed on the limiting groove of each crankshaft 2272. The retaining spring 213 is arranged on the outside of the crankshaft gear 211 to prevent the crankshaft gear 211 from axial sliding and to play a thrust role.

[0045] The end of the crankshaft 2272 near the crankshaft gear 211 is processed into a D-shaped shaft, and the D-shaped shaft of the crankshaft 2272 passes through the D-shaped hole of the crankshaft gear 211. The use of a gear with a D-shaped hole can prevent the gear and the crankshaft 2272 from slipping. At the same time, the design of the D-shaped shaft and the retaining ring 213 makes it easy to replace the crankshaft gear 211.

[0046] There are three bearing holes on the cycloid disk A2251 and the cycloid disk B2252, and a flange bearing 2271 is installed in each bearing hole. The flange bearing 2271 and the gasket 2273 are respectively fixed to the connecting rod journal and the main journal of the crankshaft 2272. The two cycloid disks are placed opposite each other to offset the eccentric vibration generated by the movement of a single cycloid disk. In view of the working conditions of the 3D printer extruder, the reduction mechanism should have a long life and high stability design. Therefore, all rotating positions on the crankshaft 2272 adopt a ball bearing design, and gaskets are used to separate the bearings and between the bearings and other components to avoid unnecessary friction caused by axial slippage of the bearings; furthermore, needle roller holes are machined on the housing A2231 and the housing B2232. The needle roller 224 passes through the needle roller holes of the housing A2231 and the housing B2232. The bearing ring 222 axially limits the needle roller 224 to prevent it from sliding out of the installation groove. For the specific configuration of the crankshaft bearings and the gear installation method, please refer to Figure 4 Cross-sectional view of the reduction mechanism.

[0047] Compared with the traditional shell as the cycloid tooth design, the use of needle roller 224 can greatly reduce the difficulty of processing, and the needle roller 224 can be made of bearing steel, which is wear-resistant and durable. The needle roller 224 can also be disassembled separately, which is convenient for maintenance after damage, greatly reducing the maintenance cost of the equipment.

[0048] The reduction mechanism used in the present invention achieves a first-stage reduction through motor gear 212 and crankshaft gear 211, with a reduction ratio of 1.25. Crankshaft 2272 achieves a cycloidal reduction effect through cycloidal disks A2251 and B2252 and needle roller 224, with a reduction ratio of 25. This second-stage reduction effect enables the reducer to achieve a reduction ratio of 31.25. Through the second-stage reduction of the motor power by the reduction mechanism, the printing material 1 is extruded through the main extrusion wheel 41 and two passive extrusion wheels, achieving a high extrusion force and achieving high stability when extruding high-hardness consumables.

[0049] Two large-diameter thin-walled bearings 221 are fixed on the housing A2231 and the reduction mechanism housing B2232. The large end face of the adapter 42 is fixed on the output flange B2262, and the optical axis part at the other end is fixed on the inner ring of the adapter bearing 43. The main extrusion wheel shaft has two thin-walled bearings 221 and one adapter bearing 43 fixed. The large-diameter thin-walled bearing 221 has a larger diameter than the ordinary extruder extrusion wheel bearing, which realizes the high stability, high load capacity and long life of the main extrusion wheel 41.

[0050] The process of two-stage deceleration is: The driving motor 6 is energized to drive the motor gear 212 to rotate, and the motor gear 212 meshes with the three crankshaft gears 211 and drives them to rotate, completing the first stage of reduction (the gear ratio of the motor gear 212 to the crankshaft gear 211 is 16:20, and the reduction ratio is 1:1.25).

[0051] The three crankshaft gears 211 all obtain power and evenly transmit the power from the drive motor 6 to the three crankshafts 2272. The rotation of the crankshaft 2272 causes the cycloid disk A2251 and the cycloid disk B2252 to revolve eccentrically through the flange bearing 2271. The cycloid disks A2251 and B2252 perform eccentric motions with opposite phases (to offset the inertial force). Since the number of teeth of the cycloid wheel is one less than the number of needle rollers fixed on the housing A2231 and the housing B2232 of the reducer, the cycloid wheel will rotate in the opposite direction by one tooth pitch per revolution. This "revolution + rotation" compound motion is transmitted to the output flange A2261 and the output flange B2262 through the crankshaft 2272 and the flange bearing 2271, converting the high-speed input into a low-speed, high-torque rotational output.

[0052] The design of the reduction mechanism is based on the principles of high reduction ratio, easy manufacturing, long life and easy maintenance. This is reflected in the design as follows: 1. All rotating contact surfaces of the crankshaft 2272 use flange bearings 2271. The flange bearings 2271 can cooperate with the reducer housing to limit the axial position of the crankshaft 2272. Washers are used to raise the inner ring of the bearing to prevent the outer ring of the bearing from rubbing against other mechanical parts, ensuring smooth rotation.

[0053] 2. The housing A2231 and housing B2232 of the reducer have multiple functions. They can serve as bearing seats for thin-walled bearings 221, and can also form the outer ring needle teeth of the cycloid reducer together with the needle roller 224. Using finished needle rollers instead of directly processing the housing into a needle tooth shape greatly reduces the difficulty of processing the housing. Using needle rollers installed on the housing as the outer ring needle teeth of the cycloid reducer has the following advantages: needle rollers are easy to process and easy to obtain. Needle rollers are made of bearing steel, which is more durable than the stainless steel or aluminum alloy material of the housing. In addition, the needle rollers are installed on the reducer housing and are easy to replace if damaged, without replacing the entire housing.

[0054] 3. Crankshaft 2272 and crankshaft gear 211 utilize a D-shaped hole transition fit. Compared to a circular hole interference fit, this allows for easy replacement of crankshaft gear 211 for maintenance. Furthermore, the D-shaped hole is impact-resistant, making it more suitable for the frequent starts, stops, and reversals of 3D printing extruders. A retaining spring is also used to axially limit the crankshaft gear, preventing it from slipping during frequent starts, stops, and reversals, thereby improving the reducer's stability.

[0055] 4. The bearing backing ring 222 has multiple functions: (1) It reduces the difficulty of processing the reducer housing. If a step ring of the same shape is processed on the reducer housing, the manufacturing difficulty of the reducer housing will be greatly increased; (2) It supports the outer ring of the thin-walled bearing 221 to prevent friction between the inner ring of the bearing and the reducer housing; (3) It axially limits the needle roller 224 installed in the needle roller hole of the reducer housing to prevent the needle roller from slipping out of the hole.

[0056] 5. The crankshaft gear on the output flange A is directly engaged with the motor gear. There are three mounting positions for the crankshaft gear on the output flange A. Since the output flange B does not have a crankshaft gear structure, it is designed to cooperate with the hexagonal connector 42. The two flange structures are reasonably and compactly designed. The hexagonal connector is responsible for transmitting the power of the reducer's deceleration and amplification torque to the main extrusion wheel. The six uniformly bearing surfaces of the hexagonal connector can evenly distribute the torque load, reducing local stress concentration compared to the four-corner or triangular design.

[0057] 6. The output flange A2261, the output flange B2262 and the hexagonal connector 42 can be regarded as the shaft of the main extrusion wheel 41, which is equivalent to two large-diameter thin-walled bearings and one ordinary bearing on one shaft. The thin-walled bearing 221 is not only the output flange support bearing of the reducer, but also can withstand the radial load from the main extrusion wheel 41. The large thin-walled bearing can disperse the load with the help of the large-diameter bearing, reduce the contact stress, and thus improve the life of the bearing.

[0058] See also Figure 3 and Figure 6 , which shows a schematic diagram of the operating mechanism designed by the present invention.

[0059] Figure 6 This is an exploded view of the operating mechanism 3. The operating mechanism 3 includes a passive extrusion wheel A311, a passive extrusion wheel B312, a balance beam frame 39, a handle frame 38 and an adjustment mechanism.

[0060] The passive extrusion wheel A311 and the passive extrusion wheel B312 are mounted on a balance beam frame 39 . The balance beam frame 39 is mounted on the handle frame 38 and can swing within a certain range.

[0061] The main extrusion wheel 41 and the passive extrusion wheel are a new gear structure, with a U-shaped consumable material engaging surface 412 and a helical gear design symmetrical on both sides on the outer surface. The middle is a U-shaped consumable material engaging surface 412, and the U-shaped consumable material engaging surface 412 is symmetrically designed as helical gears on both sides.

[0062] The surfaces of the main extrusion wheel 41 and the passive extrusion wheel that are in contact and friction with the consumables both adopt U-shaped consumable bite surface 412 extrusion surface, which has a larger contact area with the consumable wire, effectively avoiding the local crushing phenomenon of high-hardness consumables under high pressure. The wrapped structure of the U-shaped consumable bite surface 412 can also adapt to the consumable diameter tolerance to prevent radial deviation. The surface of the U-shaped consumable bite surface 412 is covered with rough metal horizontal stripes to further increase the friction between the extrusion wheel and the consumable.

[0063] Both the main extrusion wheel 41 and the passive extrusion wheel adopt a bilaterally symmetrical helical gear design. The bilaterally symmetrical helical gear linkage can offset the axial forces generated by the left and right rotating helical teeth, avoiding the gear shaft from being subjected to additional axial loads. The double helix structure ensures that at least two pairs of teeth are engaged at the same time, significantly reducing torque fluctuations and improving transmission smoothness.

[0064] The U-shaped filament engaging surface 412 plus the symmetrical helical gear design on both sides can solve the problem of eccentric wear of the passive extrusion gear of ordinary extruders. On one side of the ordinary passive extrusion gear is the transmission gear, and on the other side is the extrusion wheel in contact with the filament. Often, the load on one side of the extrusion wheel is much more complex and greater than that on the gear side under the influence of the spring preload, which will cause a large load difference on the bearings on both sides. If printing is frequent, the passive extrusion gear will wear eccentrically on one side of the bearing, and the clearance will become larger, thereby affecting the stability of printing.

[0065] Specifically, if Figure 6 As shown, passive extrusion wheel bearings 33 are installed in the bearing holes of the two passive extrusion wheels, and the passive extrusion wheel fixing pin 341 passes through the passive extrusion wheel bearing 33 and is fixed to the balance beam frame 39; the handle frame 38 is prefabricated with mounting holes A, upper mounting holes, and lower mounting holes, and the mounting hole A is used to install the adjustment mechanism, and the balance beam frame 39 is rotatably connected to the upper mounting hole of the handle frame 38 through the balance frame fixing pin 342; the handle fixing pin 343 passes through the extruder feed pressure plate 52 and is fixed to the lower mounting hole of the handle frame 38.

[0066] The balance beam frame 39 can rotate a certain angle around the balance frame fixing pin 342 of the handle frame 38, and the handle frame 38 has a certain rotation range on the passive extrusion wheel fixing pin 341 of the extruder feed pressure plate 52; the thumb screw 35 is fixed to the extruder feed pressure plate 52 through the spring 36, the washer 37 and the runway-shaped mounting hole of the passive handle frame 38.

[0067] The adjustment mechanism includes a thumb screw 35 and a spring 36 . The thumb screw 35 is installed in the mounting hole A. The spring 36 is wound around the rod of the thumb screw 35 . A gasket 37 is installed on the side of the spring 36 that contacts the handle frame 38 .

[0068] The passive extrusion wheel of the traditional extruder adopts a single-sided gear meshing transmission mode (the other side of the extrusion wheel is the filament biting surface). During operation, the filament biting surface contacts the filament, and the spring 36 applies pressure to the passive extrusion wheel, most of which is applied to the filament biting surface. This will cause the bearing on the side of the filament biting surface to bear a radial force much greater than the bearing on the gear side. In long-term operation, the aging of the bearings on both sides will be inconsistent, resulting in the problem of too short a bearing life on the side of the filament biting surface.

[0069] Figure 6 As can be seen in the figure, the passive extrusion wheel of the present invention has bevel gears designed on both sides of the U-shaped consumables engaging surface 412. The U-shaped consumables engaging surface 412 that bears the main pressure is designed to the middle of the passive extrusion wheel, and the bearings are symmetrically installed in the bearing mounting holes on both sides. This design balances the pressure on the bearings on both sides and extends the life of the bearings on both sides.

[0070] like Figure 7 As shown, the present invention designs a large-diameter main extrusion wheel 41 with a U-shaped consumables engaging surface 412 in the middle. The surface of the U-shaped consumables engaging surface 412 has rough metal stripes, which increases the contact area and friction with the consumables. Bevel gears 413 are designed on both sides of the U-shaped consumables engaging surface 412 to balance the axial force generated by the meshing of the helical teeth on both sides. During installation, the spline hole 411 is installed on the spline position of the connector 42, and a screwdriver is used to pass through the screw mounting hole 414 to directly fix the hexagonal connector 42 on the output flange B2262. The three screw mounting holes 414 can further reduce the weight of the main extrusion wheel and reduce the moment of inertia, making the extruder more flexible under conditions of frequent start-stop and reversing.

[0071] The balance beam 39 is mounted with two passive extrusion wheels. The contact area of ​​the two passive extrusion wheels is larger than that of a single passive extrusion wheel, making the extruder more stable in extruding the consumable 1. The balance beam 39 is mounted on the balance frame fixed pin 342, allowing the two passive extrusion wheels to swing left and right around the pin. These two extrusion wheels can then consistently align with the main extrusion wheel 41, providing a certain degree of adjustment capability and balancing the loads of the two passive extrusion wheels. Conventional passive extrusion wheel structures can result in an unbalanced load between the two extrusion wheels.

[0072] When the extruder is working, the specific process is as follows: After the driving motor 6 drives the deceleration structure 2 to perform secondary deceleration; The output flange B2262 transmits power to the adapter 42, which in turn transmits power to the main extrusion wheel 41, causing it to rotate. The printing filament 1 passes through the feed port on the motor frame 53 and enters the U-shaped material engaging surfaces 412 of the two passive extrusion wheels 311 and the U-shaped material engaging surfaces 412 of the main extrusion wheel 41. Under the rotational pressure of the main extrusion wheel 41 and the two passive extrusion wheels 311, the filament is extruded through the discharge port, completing the extrusion process.

[0073] The balancing beam 39 can rotate around the balancing beam fixing pin 342 to a certain angle, allowing the U-shaped filament engaging surfaces 412 of the two passive extruder wheels to closely contact the printing filament 1. When a greater extrusion force is required or the filament itself is relatively hard, the thumbscrew 35 can be rotated to increase the compression of the spring 36, increasing the preload applied to the two passive extruder wheels, increasing the friction between the extruder wheels and the filament, and increasing the extrusion force of the extruder. When a smaller extrusion force is required or the filament itself is relatively hard, the thumbscrew 35 can be rotated in the opposite direction to reduce the compression of the spring 36, thereby reducing the preload applied to the two passive extruder wheels and preventing deformation of the filament due to excessive pressure.

[0074] The present invention solves the problem of insufficient extrusion force of existing extruders when extruding high-hardness and high-toughness consumables: a reduction ratio of 31.25 between the motor output shaft and the extrusion wheel is achieved by using a reduction mechanism, which achieves a larger reduction ratio than the traditional reduction extruder under the same volume, ensuring that the extrusion wheel achieves high torque output; compared with the small bearings commonly used in extruders on the market, the two large-diameter 6706 bearings on the reducer and the 608 bearings on the extrusion wheel output shaft can allow the extrusion wheel to achieve higher loads and longer life; the herringbone extrusion wheel and the passive extrusion wheel of the metal 3D printing process after heat treatment have no axial force compared to ordinary helical gears on the market, and will not have the problem of eccentric wear of the handle; the double-floating passive extrusion wheel design solves the problem of unbalanced load on the two wheels of the ordinary double passive extrusion wheel, and the passive extrusion wheel with a floating design can better fit the consumables than the ordinary passive extrusion wheel, has a larger force area and a more balanced load.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A compact extruder, characterized in that: It includes a speed reduction mechanism (2), an operating mechanism (3), a main extrusion wheel structure (4), an extruder frame (5) and a drive motor (6); The speed reduction mechanism (2) and the main extrusion wheel structure (4) are installed in the extruder frame (5), and the operating mechanism (3) is installed on one side of the main extrusion wheel structure (4); the output shaft of the drive motor (6) is connected to the speed reduction mechanism (2); The main extrusion wheel structure (4) includes a main extrusion wheel (41) and a connector (42), and the main extrusion wheel (41) is connected to the speed reduction mechanism (2) via the connector (42); The operating mechanism (3) includes a passive extrusion wheel A (311), a passive extrusion wheel B (312), a balance beam frame (39), a handle frame (38), and an adjustment mechanism; the passive extrusion wheel A (311) and the passive extrusion wheel B (312) are mounted on the balance beam frame (39), the balance beam frame (39) is mounted on the handle frame (38), and the adjustment mechanism is mounted on the outside of the handle frame (39); The passive extrusion wheel A (311) and the passive extrusion wheel B (312) are both meshed with the main extrusion wheel (41); the center of the outer peripheral surface of the main extrusion wheel (41) and the two passive extrusion wheels is a U-shaped consumable material bite surface (412), the surface of the U-shaped consumable material bite surface (412) is covered with rough metal horizontal stripes, and the two sides of the U-shaped consumable material bite surface (412) are symmetrically designed as helical gears (413); the filament (1) is clamped between the U-shaped consumable material bite surfaces (412) of the main extrusion wheel (41) and the two passive extrusion wheels (311), and is stably output under the action of rotational extrusion.

2. A compact extruder according to claim 1, characterized in that, The speed reduction mechanism (2) includes a housing A (2231) and a housing B (2232), wherein a gear speed reduction structure and a cycloid speed reduction structure are installed in the housing A (2231) and the housing B (2232); The gear reduction structure comprises a motor gear (212) and three crankshaft gears (211) mounted on the output shaft of the drive motor (6); the motor gear (212) and the three crankshaft gears (211) are meshed and linked to perform a first-stage reduction; The cycloid reduction structure comprises an output flange A (2261), an output flange B (2262), a crankshaft (2272), a cycloid disk A (2251), and a cycloid disk B (2252); the crankshaft (2272) is linked to the crankshaft gear (211); the crankshaft (2272) is linked to the cycloid disk A (2251) and the cycloid disk B (2252) to perform secondary reduction; The motor gear (212) and the three crankshaft gears (211) are installed in the output flange A (2261), the output flange A (2261) is installed in the housing A (2231), and the output flange B (2261) is installed in the housing B (2232); the crankshaft (2272) sequentially passes through the crankshaft gear (211), the cycloid disk A (2251) and the cycloid disk B (2252), the cycloid disk A (2251) is installed in the housing A (2231), and the cycloid disk B (2252) is installed in the housing B (2232); Flange bearings (2271) are used on all rotating contact surfaces of the crankshaft (2272).

3. A compact extruder according to claim 2, characterized in that, The output flange A (2261) is mounted in the housing A (2231) via a thin-walled bearing (221); the output flange B (2261) is mounted in the housing B (2232) via another thin-walled bearing (221); and the adapter bearing (43) is mounted in the adapter bearing mounting bracket (51).

4. A compact extruder according to claim 2, characterized in that, Shell A (2231) and shell B (2232) are machined with needle roller holes, and a plurality of needle rollers (224) are installed in the needle roller holes; A bearing ring (222) is provided between the thin-walled bearing (221) and the housing A (2231), and between the thin-walled bearing (221) and the housing B (2232); The number of teeth on the cycloid disc is one less than that on the needle roller (224).

5. A compact extruder according to claim 2, characterized in that: A limiting groove for installing a retaining ring (213) is machined at the end of the crankshaft (2272). A retaining ring (213) is installed on the limiting groove of each crankshaft (2272). The retaining ring (213) is arranged on the outside of the crankshaft gear (211).

6. A compact extruder according to claim 2, characterized in that: A D-shaped hole is machined in the center of the crankshaft gear (211), and one end of the crankshaft (2272) close to the crankshaft gear (211) is machined into a D-shaped shaft. The D-shaped shaft is located inside the limiting groove, and the D-shaped shaft of the crankshaft (2272) passes through the D-shaped hole of the crankshaft gear (211).

7. A compact extruder according to claim 1, characterized in that: The handle frame (38) is prefabricated with a mounting hole A, an upper mounting hole, and a lower mounting hole; The adjustment mechanism includes a thumb screw (35) and a spring (36), wherein the thumb screw (35) is installed in the mounting hole A, the spring (36) is wound around the rod of the thumb screw (35), and a gasket (37) is installed on the side of the spring (36) that contacts the handle frame (38); The balance beam frame (39) is rotatably connected to the upper mounting hole of the handle frame (38) via the balance frame fixing pin (342); the handle fixing pin (343) passes through the lower mounting hole of the handle frame (38) and is connected to the extruder frame (5).

8. A compact extruder according to claim 1, characterized in that: The extruder frame (5) includes a coupling bearing mounting frame (51), an extruder feed pressing plate (52) and a motor frame (53); the speed reduction mechanism (2) is installed in the motor frame (53), and the drive motor (6) is installed on one side of the motor frame (53); the main extrusion wheel structure (4) is installed in the extruder frame (5); a feeding hole is prefabricated on the extruder feed pressing plate (52), and the extruder feed pressing plate (52) is connected to the operating mechanism (3).

9. The extrusion method of a compact extruder according to any one of claims 1 to 8, characterized in that: The following processes are included: After the driving motor (6) drives the deceleration structure (2) to decelerate, the deceleration structure (2) transmits power to the adapter (42), and the adapter (42) transmits power to the main extrusion wheel (41), and the main extrusion wheel (41) starts to rotate; The printing consumables filament (1) passes through the feed port on the extruder frame (5) and enters the U-shaped consumables engaging surface (412) of the two passive extrusion wheels and the main extrusion wheel (41). Under the rotational extrusion action of the main extrusion wheel (41) and the two passive extrusion wheels, the printing consumables filament (1) is extruded through the discharge port to complete the extrusion operation; During extrusion, the balance beam frame (39) rotates around the handle frame (38) so that the U-shaped consumables engaging surfaces (412) of the two passive extrusion wheels are in close contact with the printing consumables filament (1); When a larger extrusion force is required or the hardness of the filament itself is relatively high, the pre-pressure applied to the two passive extrusion wheels is increased through the adjustment mechanism to increase the extrusion force of the extruder; when a smaller extrusion force is required or the hardness of the filament itself is relatively low, the pre-pressure applied to the two passive extrusion wheels is reduced through the adjustment mechanism.

10. The extrusion method of a compact extruder according to claim 9, characterized in that: The deceleration process of the deceleration structure (2) is as follows: The driving motor (6) is energized to drive the motor gear (212) to rotate, and the motor gear (212) meshes with the three crankshaft gears (211) and drives them to rotate, completing the first stage of deceleration; The three crankshaft gears (211) all receive power and evenly transmit the power from the drive motor (6) to the three crankshafts (2272). The crankshafts (2272) rotate to cause the cycloid disk A (2251) and the cycloid disk B (2252) to perform eccentric orbital motion, and the cycloid disk A (2251) and the cycloid disk B (2252) to perform eccentric motion with opposite phases. The number of teeth of the cycloid disk is one less than that of the needle roller (224). The cycloid disk rotates in the opposite direction by one tooth pitch every time it orbits one circle. The combined motion of the orbital and rotational motion is transmitted to the output flange A (2261) and the output flange B (2262) through the crankshaft (2272) and the flange bearing (2271), completing the second stage of deceleration.

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