Closed-loop wire feeding device of 3D printer

Abstract

The invention discloses a closed-loop wire feeding device of a 3D printer, and belongs to the technical field of 3D printing. The problem that a driving motor in an existing wire feeding mechanism cannot form closed-loop control, and consequently the wire feeding precision is poor is solved. The closed-loop wire feeding device comprises a mounting table, wherein a wire feeding mechanism and a detection mechanism are mounted on the mounting table; the wire feeding mechanism comprises a first support, a first friction wheel is installed on the first support, and the first friction wheel is in transmission connection with a driving motor; the detection mechanism comprises a second support, and a second friction wheel is installed on the second support. The second friction wheel is in transmission connection with the encoder; the driving motor and the encoder are electrically connected with the control system. According to the device, the driving motor drives the first friction wheel to rotate, and the first friction wheel drives the printing silk material to move through friction force; and the encoder detects the movement information of the printing silk material and transmits the movement information to the control system to form closed-loop control, so that the accurate control of the driving motor is realized, and the 3D printing precision is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and particularly to a closed-loop wire feeding device for a 3D printer. Background Art

[0002] 3D printing technology integrates technologies in multiple fields such as digital technology, manufacturing technology, laser technology, and new material technology. It can directly and precisely manufacture a three-dimensional solid part from a CAD digital model quickly. Fused deposition modeling (FDM) is one of the 3D printing technologies. The fused deposition modeling technology uses a filamentous wire (such as PLA or ABS plastic, etc.) as the material. During forming, the filamentous wire is heated to a molten state by a heating device, and the molten wire is extruded from the nozzle through a wire feeding and extrusion mechanism. When performing 3D printing, first, the upper computer software slices the model of the object to be printed to generate a workflow file that the printer can recognize, usually a GCode file. The GCode file gives the moving positions and speeds of each axis of the 3D printer at each step. During the fused deposition modeling process, the wire material at the nozzle needs to be extruded at the desired speed given by the GCode file. If the extrusion speed of the nozzle is too fast, it will cause the molten wire at the extrusion head to pile up, and the printing material will be unevenly distributed, making the printed model rough and not smooth. On the contrary, it will cause the wire breakage phenomenon.

[0003] Currently, most fused deposition modeling printers use a stepper motor to provide the driving force for the wire feeding mechanism. Among them, the operation of the stepper motor is directly controlled by the upper computer, and there is no closed-loop control of the stepper motor based on the actual wire feeding information as a feedback quantity. Therefore, the control accuracy of the wire feeding mechanism is poor, and when the starting frequency is too high or the load is too large, the phenomenon of losing steps or jamming is likely to occur. Summary of the Invention

[0004] Aiming at the deficiencies existing in the prior art, the present invention provides a closed-loop wire feeding device for a 3D printer, which solves the problem that the driving motor in the existing wire feeding mechanism cannot form a closed-loop control, resulting in poor wire feeding accuracy.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A closed-loop wire feeding device for a 3D printer includes an installation table, on which a wire feeding mechanism and a detection mechanism are installed; the wire feeding mechanism includes a first bracket, and the first bracket is fixedly connected to the installation table; a first friction wheel is installed on the first bracket, and the first friction wheel is in transmission connection with a driving motor; the detection mechanism includes a second bracket, and the second bracket is fixedly connected to the installation table; a second friction wheel is installed on the second bracket; the second friction wheel is in transmission connection with an encoder; the driving motor and the encoder are respectively electrically connected to a control system.

[0006] In this solution, during the 3D printing process, the control system controls the movement of the driving motor. The driving motor drives the first friction wheel to rotate. The edge of the first friction wheel abuts against the printing filament, and the first friction wheel drives the movement of the printing filament by using frictional force. While the printing filament is moving, it drives the second friction wheel to rotate. The encoder can detect the rotation angle of the second friction wheel in real time and transmit it to the control system. The control system performs closed-loop control on the driving motor according to the rotation angle of the second friction wheel, achieving precise control of the driving motor, ensuring that the actual wire feeding speed of the printing filament meets the expected wire feeding speed, and avoiding phenomena such as slipping and jamming during the wire feeding process, which helps to improve the 3D printing accuracy.

[0007] Further, a first pressing rod with an L-shaped structure is movably connected to the first bracket through a first fixing pin. One end of the first pressing rod is movably connected to a first auxiliary wheel, and a first spring is arranged between the other end of the first pressing rod and the side wall of the first bracket. The printing filament is clamped between the first friction wheel and the first auxiliary wheel. A second pressing rod with an L-shaped structure is movably connected to the second bracket through a second fixing pin. One end of the second pressing rod is movably connected to a second auxiliary wheel, and a second spring is arranged between the other end of the second pressing rod and the side wall of the second bracket. The printing filament is clamped between the second friction wheel and the second auxiliary wheel.

[0008] In this solution, under the elastic force of the first spring, the first pressing rod rotates relative to the first fixing pin, and the first auxiliary wheel at the end of the first pressing rod presses the printing filament against the first friction wheel, avoiding slipping between the first friction wheel and the printing filament. Similarly, the second spring drives the second auxiliary wheel to approach the second friction wheel through the second pressing rod, making the printing filament closely adhere to the second friction wheel, avoiding inaccurate information detected by the encoder.

[0009] Further, the edges of the first friction wheel and the second friction wheel are gear-shaped; the edges of the first auxiliary wheel and the second auxiliary wheel are semi-circular grooves.

[0010] In this solution, the semi-circular groove design of the edge of the first auxiliary wheel can form good limit for the printing filament, ensuring its stable movement; the gear-shaped design of the edge of the first friction wheel can increase the frictional force with the printing filament.

[0011] Further, a wire passing hole is formed in the side wall of the second bracket, and a conduit is installed in the wire passing hole. The printing filament passes through the conduit.

[0012] In this solution, the wire passing hole plays a guiding role for the printing filament. After passing through the wire passing hole, the printing filament is exactly located in the middle of the second friction wheel and the second auxiliary wheel. The conduit is used to reduce the frictional resistance to the printing filament.

[0013] Furthermore, the drive motor is installed on the side of the mounting table; the top of the drive motor is connected to the first bracket, and the output shaft of the drive motor passes through the through hole on the first bracket and is connected to the first friction wheel.

[0014] Furthermore, two side wings are provided on one side of the mounting table close to the drive motor, and the drive motor is clamped and fixed between the two side wings.

[0015] In this solution, this design can stably fix the drive motor on the mounting table.

[0016] Furthermore, the encoder is fixed to the bottom of the mounting table; the rotating shaft of the encoder passes through the through holes on the mounting table and the second bracket and is connected to the second friction wheel.

[0017] The beneficial effects of the present invention are as follows: In the closed-loop wire feeding device of the 3D printer provided by the present invention, the drive motor drives the movement of the printing wire through the first friction wheel. At the same time, the encoder can detect the rotation angle of the second friction wheel in real time and transmit it to the control system. The control system determines the actual wire feeding length and wire feeding speed according to the rotation angle of the second friction wheel, and then forms a closed-loop control for the drive motor according to the actual wire feeding length and wire feeding speed. The input quantity of the closed-loop control is the expected wire feeding length and wire feeding speed, and the feedback quantity of the closed-loop control is the actual wire feeding length and wire feeding speed obtained according to the information collected by the encoder. The stepping motor is controlled according to the deviation between the expected value and the actual value, effectively avoiding phenomena such as slipping and jamming during the wire feeding process, and helping to improve the 3D printing accuracy. In addition, according to the rotation angle of the second friction wheel detected by the encoder, the wire breakage situation of the printing wire can be judged in time and the printing can be paused. Description of the Drawings

[0018] Figure 1 is a schematic structural diagram of a closed-loop wire feeding device of a 3D printer according to the present invention; Figure 2 is a side view of a closed-loop wire feeding device of a 3D printer according to the present invention; Figure 3 is a schematic structural diagram of the mounting table and the drive motor in the present invention.

[0019] Reference Signs: 1, mounting table; 11, side wing; 2, wire feeding mechanism; 21, first bracket; 22, first auxiliary wheel; 23, first friction wheel; 24, drive motor; 25, first pressing rod; 26, first spring; 27, first fixing pin; 3, detection mechanism; 31, second bracket; 32, second auxiliary wheel; 33, second friction wheel; 34, encoder; 35, second pressing rod; 36, second spring; 37, second fixing pin; 38, conduit; 4, printing wire. Detailed Embodiments

[0020] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The following describes the specific embodiments of the present invention to facilitate those skilled in the art of this technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

[0021] Embodiment 1 As Figure 1 shown, this embodiment provides a closed-loop wire feeding device for a 3D printer. This closed-loop wire feeding device for a 3D printer realizes closed-loop control of the wire feeding motor and can effectively improve the accuracy of wire feeding. Specifically, it includes: a mounting table 1, a wire feeding mechanism 2, a detection mechanism 3, and a control system; Among them, the wire feeding mechanism 2 and the detection mechanism 3 are mounted on the mounting table 1; the wire feeding mechanism 2 is used to drive the movement of the printing filament 4, the detection mechanism 3 is used to collect information on the movement of the printing filament 4, and the control system forms a closed-loop control of the wire feeding mechanism 2 according to the information collected by the detection mechanism 3.

[0022] As Figure 2 shown, the wire feeding mechanism 2 includes a first bracket 21, a first friction wheel 23, a first auxiliary wheel 22, a driving motor 24, a first pressing rod 25, a first spring 26, and a first fixing pin 27.

[0023] The first bracket 21 is fixedly connected to the mounting table 1; the first friction wheel 23 is mounted on the first bracket 21; the driving motor 24 is mounted on the side of the mounting table 1; the output shaft of the driving motor 24 passes through the through hole on the first bracket 21 and is in transmission connection with the first friction wheel 23; two side wings 11 are provided on one side of the mounting table 1 close to the driving motor 24, and the driving motor 24 is clamped and fixed between the two side wings 11, as Figure 3 shown; the driving motor 24 is electrically connected to the control system.

[0024] The first pressing rod 25 with an L-shaped structure is movably connected to the first bracket 21 through the first fixing pin 27; one end of the first pressing rod 25 is movably connected to the first auxiliary wheel 22, and a first spring 26 is provided between the other end of the first pressing rod 25 and the side wall of the first bracket 21; the printing filament 4 is clamped between the first friction wheel 23 and the first auxiliary wheel 22; under the elastic force of the first spring 26, the first pressing rod 25 rotates relative to the first fixing pin 27, and the first auxiliary wheel 22 at the end of the first pressing rod 25 presses the printing filament 4 against the first friction wheel 23, ensuring that there is sufficient friction between the first friction wheel 23 and the printing filament 4 and avoiding slippage between the first friction wheel 23 and the printing filament 4.

[0025] The detection mechanism 3 includes a second support 31, a second auxiliary wheel 32, a second friction wheel 33, an encoder 34, a second pressure rod 35, a second spring 36, a second fixing pin 37, and a conduit 38.

[0026] The second support 31 is fixedly connected to the mounting table 1, and the second friction wheel 33 is mounted on the second support 31; the encoder 34 is fixed to the bottom of the mounting table 1; the rotating shaft of the encoder 34 passes through the through holes in the mounting table 1 and the second support 31 and is in driving connection with the second friction wheel 33; the encoder 34 is electrically connected to the control system.

[0027] The second support 31 is movably connected with an L-shaped second pressure rod 35 through a second fixing pin 37; one end of the second pressure rod 35 is movably connected with a second auxiliary wheel 32, and a second spring 36 is arranged between the other end of the second pressure rod 35 and the side wall of the second support 31; the printing filament 4 is clamped between the second friction wheel 33 and the second auxiliary wheel 32; the second spring 36 drives the second auxiliary wheel 32 to approach the second friction wheel 33 through the second pressure rod 35, so that the printing filament 4 is closely attached to the second friction wheel 33.

[0028] A wire passing hole is formed in the side wall of the second support 31, and a conduit 38 is installed in the wire passing hole, and the printing filament 4 passes through the conduit 38. The wire passing hole plays a guiding role for the printing filament 4, and the printing filament 4 is exactly located in the middle of the second friction wheel 33 and the second auxiliary wheel 32 after passing through the wire passing hole; the conduit 38 is used to reduce the frictional resistance to the printing filament 4.

[0029] The edges of the first friction wheel 23 and the second friction wheel 33 are gear-shaped, which can increase the friction force between them and the printing filament 4. The edges of the first auxiliary wheel 22 and the second auxiliary wheel 32 are semi-circular grooves, which form good limits for the printing filament 4 and ensure its stable movement.

[0030] As a preference of this embodiment, the driving motor 24 is preferably a stepping motor.

[0031] During the 3D printing process, the control system controls the movement of the driving motor 24, the driving motor 24 drives the first friction wheel 23 to rotate, and the first friction wheel 23 drives the printing filament 4 to move by using the friction force; while the printing filament 4 is moving, it will drive the second friction wheel 33 to rotate, and the encoder 34 can detect the rotation angle of the second friction wheel 33 in real time and transmit it to the control system. The control system performs closed-loop control on the driving motor 24 according to the rotation angle of the second friction wheel 33, realizes precise control of the driving motor 24, ensures that the actual moving speed of the printing filament 4 meets the expected wire feeding speed, avoids phenomena such as slipping and jamming during the wire feeding process, and helps to improve the 3D printing accuracy.

[0032] Embodiment 2 Based on the closed-loop wire feeding device of a 3D printer provided in Embodiment 1, this embodiment provides a closed-loop wire feeding control method for a 3D printer, including the following steps: Step S1: The control system controls the movement of the driving motor 24, and the driving motor 24 drives the first friction wheel 23 to rotate; the first friction wheel 23 drives the movement of the printing wire 4 by using friction; Step S2: The printing wire 4 drives the second friction wheel 33 to rotate; the encoder 34 detects the rotation angle of the second friction wheel 33 in real time and transmits it to the control system; Step S3: The control system determines the actual wire feeding length and wire feeding speed according to the rotation angle of the second friction wheel 33, and compares the deviation between the actual wire feeding length and wire feeding speed and the set desired wire feeding length and wire feeding speed; Step S4: According to the deviation, the control system obtains the control amount of the stepping motor according to the control algorithm, and controls the stepping motor according to the control amount.

[0033] During the printing process, if the printing wire 4 runs out or breaks, etc., the encoder 34 will not have signal changes for a long time. The control system judges that the printing wire 4 is out of stock accordingly, and can send a signal and pause the printing.

[0034] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A closed-loop wire feeding device for a 3D printer, characterized in that: It comprises a mounting platform (1), on which a wire feeding mechanism (2) and a detection mechanism (3) are mounted; The wire feeding mechanism (2) comprises a first bracket (21), the first bracket (21) being fixedly connected to the mounting platform (1); a first friction wheel (23) is mounted on the first bracket (21), and the first friction wheel (23) is transmission-connected to a driving motor (24); The detection mechanism (3) comprises a second bracket (31), the second bracket (31) being fixedly connected to the mounting platform (1); a second friction wheel (33) being mounted on the second bracket (31); and the second friction wheel (33) being transmission-connected to an encoder (34); The drive motor (24) and the encoder (34) are respectively electrically connected to a control system.

2. The closed-loop wire feeding device for a 3D printer according to claim 1, characterized in that: A first pressure rod (25) of an L-shaped structure is movably connected to the first bracket (21) via a first fixing pin (27); one end of the first pressure rod (25) is movably connected to a first auxiliary wheel (22), and a first spring (26) is provided between the other end of the first pressure rod (25) and a side wall of the first bracket (21); The printing filament (4) is clamped between the first friction wheel (23) and the first auxiliary wheel (22); A second pressure rod (35) of an L-shaped structure is movably connected to the second bracket (31) via a second fixing pin (37); one end of the second pressure rod (35) is movably connected to a second auxiliary wheel (32), and a second spring (36) is provided between the other end of the second pressure rod (35) and a side wall of the second bracket (31); and the printing wire (4) is clamped between the second friction wheel (33) and the second auxiliary wheel (32).

3. The closed-loop wire feeding device for a 3D printer according to claim 2, characterized in that: The edges of the first friction wheel (23) and the second friction wheel (33) are gear-shaped; The edges of the first auxiliary wheel (22) and the second auxiliary wheel (32) are semicircular grooves.

4. The closed-loop wire feeding device for a 3D printer according to claim 2, characterized in that: A wire passing hole is provided on the side wall of the second bracket (31), a guide tube (38) is installed in the wire passing hole, and the printing filament (4) passes through the guide tube (38).

5. The closed-loop wire feeding device for a 3D printer according to claim 1, characterized in that: The drive motor (24) is mounted on a side of the mounting platform (1); the top of the drive motor (24) is connected to the first bracket (21); the output shaft of the drive motor (24) passes through a through hole on the first bracket (21) and is connected to the first friction wheel (23).

6. The closed-loop wire feeding device for a 3D printer according to claim 5, characterized in that: Two side wings (11) are provided on one side of the mounting platform (1) close to the drive motor (24), and the drive motor (24) is clamped and fixed between the two side wings (11).

7. The closed-loop wire feeding device for a 3D printer according to claim 1, characterized in that: The encoder (34) is fixed to the bottom of the mounting platform (1); the rotating shaft of the encoder (34) passes through the through holes on the mounting platform (1) and the second bracket (31), and is connected to the second friction wheel (33).

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