3D printer automatic material changing device and automatic material changing method

Abstract

The present invention discloses an automatic material changing device and an automatic material changing method for a 3D printer, wherein the device includes an extrusion mechanism and a switching mechanism; the extrusion mechanism includes a driving wheel, a first driven wheel group, a second driven wheel group, a first rotating clamp, a second rotating clamp, and a tension spring, one end of the first rotating clamp and the second rotating clamp are both hinged to a cover body, and the other ends of the first rotating clamp and the second rotating clamp are connected by a tension spring; the switching mechanism includes a switching rod rotatably connected to an extrusion base, and a switching handle fixedly connected to the switching rod; the end of the first rotating clamp close to the tension spring is fixedly connected to a first limiting post, and the end of the second rotating clamp close to the tension spring is fixedly connected to a second limiting post; when the switching handle is in an initial state, the two ends of the switching rod respectively abut against the first limiting post and the second limiting post, so that the first driven wheel group and the second driven wheel group are both separated from the driving wheel. The present invention has a high degree of automation, improves work efficiency, and saves labor costs.

Description

Technical Field

[0001] The present invention relates to the field of 3D printing, and more particularly to an automatic material changing device and an automatic material changing method for a 3D printer. Background Art

[0002] During the 3D printing process, an extruder drives filament into the nozzle, where the molten filament is squeezed out of the nozzle to print. However, the filament may run out during printing, requiring the operator to stay at the printer for a long time to manually replace the filament. If the filament tray is not replaced in time, the print will fail, greatly reducing work efficiency and filament utilization. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an automatic material changing device and an automatic material changing method for a 3D printer.

[0004] To achieve the above objectives, the present invention adopts the following technical solutions: an automatic material changing device for a 3D printer, comprising a cover, an extrusion mechanism, a switching mechanism, and a motor; the cover is provided with a mounting cavity, and the extrusion mechanism and the switching mechanism are both mounted in the mounting cavity; the extrusion mechanism comprises a driving wheel, a first driven wheel group, a second driven wheel group, a first rotating clamp, a second rotating clamp, and a tension spring; one end of each of the first rotating clamp and the second rotating clamp is hinged to the cover, and the other ends of the first rotating clamp and the second rotating clamp are connected by the tension spring; the driving wheel is located between the first rotating clamp and the second rotating clamp; the output shaft of the motor is connected to the driving wheel; the switching mechanism comprises a switching rod rotatably connected to the cover, and a switching handle fixedly connected to the switching rod; a first limiting post is fixedly connected to the end of the first rotating clamp near the tension spring, and a second limiting post is fixedly connected to the end of the second rotating clamp near the tension spring; when the switching handle is rotated toward the first driven wheel group, the first driven wheel group engages with the driving wheel, and when the switching handle is rotated toward the second driven wheel group, the second driven wheel group engages with the driving wheel.

[0005] Its further technical solution is: the first driven wheel group includes a first switching gear and a first extrusion bearing; the first switching gear is installed above the first extrusion bearing, and the first switching gear is provided with a first protrusion; the second driven wheel group includes a second switching gear and a second extrusion bearing; the second switching gear is installed above the second extrusion bearing, and the second switching gear is provided with a second protrusion.

[0006] A further technical solution is: a first blocking portion is provided at one end of the switching rod, and a second blocking portion is provided at the other end of the switching rod.

[0007] Its further technical solution is: one end of the switching rod is provided with a first concave arc surface, and the first concave arc surface constitutes a guide surface abutting against the first limiting column; the other end of the switching rod is provided with a second concave arc surface, and the second concave arc surface constitutes a guide surface abutting against the second limiting column.

[0008] Its further technical solution is: the cover body includes an extrusion base and an extrusion cover connected to the extrusion base; the extrusion base is provided with the mounting cavity, the through hole is located on the extrusion base, the motor is fixed to the bottom of the extrusion base, and the output shaft of the motor passes through the through hole and is connected to the driving wheel.

[0009] Its further technical solution is: a first tension spring column is provided on the first switching gear and the extrusion base, a second tension spring column is provided on the second switching gear and the extrusion base, a first spring is connected between the two first tension spring columns of the first switching gear and the extrusion base, and a second spring is connected between the two second tension spring columns of the second switching gear and the extrusion base.

[0010] Its further technical solution is: it also includes a first feed pipe, a second feed pipe, a first discharge pipe and a second discharge pipe; the first feed pipe and the first discharge pipe are respectively located at the two ends between the first driven wheel group and the driving wheel, and the second feed pipe and the second discharge pipe are respectively located at the two ends between the second driven wheel group and the driving wheel.

[0011] Its further technical solution is: the extrusion base is provided with a first fixing hole for fixing the first feed pipe, a second fixing hole for fixing the first discharge pipe, a third fixing hole for fixing the second feed pipe, and a fourth fixing hole for fixing the second discharge pipe; the first fixing hole and the second fixing hole are located on the same axis, and the third fixing hole and the fourth fixing hole are located on the same axis; the mounting cavity is also provided with a support plate for supporting the first feed pipe and the second feed pipe, and the support plate is provided with a first support hole adapted to the diameter of the first feed pipe, and a second support hole adapted to the diameter of the second feed pipe; the first support hole and the second support hole are arranged side by side.

[0012] A further technical solution is: it also includes a motor mounting plate; the motor mounting plate is fixed to the bottom of the extrusion base, and the motor is fixedly connected to the motor mounting plate.

[0013] An automatic material changing method using the above-mentioned automatic material changing device for a 3D printer, the method comprising the following steps:

[0014] Monitor the feeding channel in progress;

[0015] Determine whether the feeding channel in operation is broken;

[0016] If so, the motor is controlled to drive the driving wheel to rotate in the opposite direction to withdraw the residual wire in the feeding channel, and under the force of the driven wheel group corresponding to the feeding channel on the switching rod, the driven wheel group corresponding to the feeding channel is separated from the driving wheel, and the driven wheel group corresponding to the other feeding channel is engaged with the driving wheel.

[0017] Compared with the prior art, the present invention has the following advantages: the automatic material changing device for a 3D printer provided by the present invention controls the engagement and separation between the driven wheel group and the driving wheel by switching a handle, and utilizes the reverse rotation of the motor to realize automatic switching of the feeding channel, thereby completing automatic material changing, eliminating the need for manual monitoring and material changing, and having a high degree of automation, thereby improving work efficiency and saving labor costs.

[0018] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following preferred embodiments are specifically cited and described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an assembly diagram of a specific embodiment of the automatic material changing device for a 3D printer of the present invention;

[0020] Figure 2 This is an exploded view of a specific embodiment of the automatic material changing device for a 3D printer of the present invention;

[0021] Figure 3 This is a schematic diagram of the installation structure of the cavity components in a specific embodiment of the automatic material changing device for a 3D printer of the present invention;

[0022] Figure 4 This is a schematic diagram of the installation structure of the cavity components in a specific embodiment of the automatic material changing device for a 3D printer of the present invention (the extrusion base is not shown);

[0023] Figure 5 This is a schematic diagram of the installation structure of some components in the installation chamber in a specific embodiment of the automatic material changing device for a 3D printer of the present invention;

[0024] Figure 6 This is a schematic structural diagram of an extrusion base in a specific embodiment of the automatic material changing device for a 3D printer of the present invention;

[0025] Figure 7 This is a structural diagram of a switching mechanism in a specific embodiment of the automatic material changing device for a 3D printer of the present invention;

[0026] Figure 8 This is a structural schematic diagram of the first driven wheel group in a specific embodiment of the automatic material changing device for a 3D printer of the present invention;

[0027] Reference numerals:

[0028] 1. Cover; 11. Extrusion cover; 12. Extrusion base; 121. Mounting cavity; 122. First tension spring column; 1221. First spring; 123. Second tension spring column; 1231. Second spring; 124. First fixing hole; 125. Second fixing hole; 126. Third fixing hole; 127. Fourth fixing hole; 128. Support plate; 1281. First support hole; 1282. Second support hole; 129. Through hole; 2. Motor mounting plate; 3. Motor; 4. First rotating clamp; 41. First driven wheel group; 411. First switching gear; 4 12. First protrusion; 413. First extrusion bearing; 42. First limiting post; 43. Tension spring; 5. Second rotating clamp; 51. Second driven wheel group; 52. Second limiting post; 6. Switching mechanism; 61. Switching lever; 611. First concave arc surface; 612. First blocking portion; 613. Second concave arc surface; 614. Second blocking portion; 62. Switching handle; 7. Driving wheel; 8. First feed pipe; 9. First discharge pipe; 10. Second feed pipe; 20. Second discharge pipe; 30. First feeding channel; 40. Second feeding channel. DETAILED DESCRIPTION

[0029] In order to more fully understand the technical content of the present invention, the technical solution of the present invention is further introduced and illustrated in conjunction with specific embodiments below, but is not limited thereto.

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0033] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0034] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0035] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", "or "some examples" and the like mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0036] Example 1

[0037] This invention proposes a 3D printer automatic material changing device, see Figure 1-5, 8, the device includes a cover body 1, an extrusion mechanism, a switching mechanism 6, a motor 3, a first feed pipe 8, a second feed pipe 10, a first discharge pipe 9 and a second discharge pipe 20; the cover body 1 includes an extrusion base 12, and an extrusion cover 11 connected to the extrusion base 12; the extrusion base 12 is provided with a mounting cavity 121, and the extrusion mechanism, the switching mechanism 6, the feed pipe and the discharge pipe are all mounted in the mounting cavity 121; the extrusion mechanism includes a driving wheel 7, a first driven wheel group 41, a second driven wheel group 51, a first rotating clamp 4, a second The first and second rotating clamps 4 and 5 are hinged to each other at one end and connected to the extrusion base 12 at the other end through the tension spring 43; the first rotating clamp 4 is fixedly connected to the first limiting column 42 at one end of the tension spring 43, and the second rotating clamp 5 is fixedly connected to the second limiting column 52 at one end of the tension spring 43; the driving wheel 7 is located between the first rotating clamp 4 and the second rotating clamp 5, and the extrusion base 12 is provided with a through hole 129, and the output shaft of the motor 3 located below the extrusion base 12 is connected to the driving wheel 7 through the through hole 129; the first driven wheel group 41 includes a first switching gear 411 and a first extrusion bearing 413; the first switching gear 411 is installed above the first extrusion bearing 413, and the first switching gear 411 is provided with a first protrusion 412; the second driven wheel group 51 includes a second switching gear and a second extrusion bearing; the second switching gear is installed above the second extrusion bearing, and the second switching gear is provided with a second protrusion; the switching mechanism 6 includes a first switching gear 411 and a second extrusion bearing; the second switching gear is installed above the second extrusion bearing, and the second switching gear is provided with a second protrusion; the switching mechanism 6 includes a first switching gear 411 and a second extrusion bearing; the first switching gear 411 is fixedly connected to the second extrusion bearing; the second switching gear ... A switching rod 61 rotatably connected to the seat 12, and a switching handle 62 fixedly connected to the switching rod 61; a first blocking portion 612 is provided at one end of the switching rod 61, and a second blocking portion 614 is also provided at the other end of the switching rod 61; a first concave arc surface 611 is also provided at one end of the switching rod 61, and the first concave arc surface 611 constitutes a guide surface abutting against the first limiting column 42; a second concave arc surface 613 is also provided at the other end of the switching rod 61, and the second concave arc surface 613 constitutes a guide surface abutting against the second limiting column 52. When the first switching gear 411 rotates in the opposite direction, the first protrusion 412 will contact the first blocking portion 612, and the switching handle 62 rotates in the direction away from the first driven wheel group 41, and the first concave arc surface 611 of the switching lever 61 contacts the first limiting column 42, which is used to prevent the first rotating clamp 4 from approaching the driving wheel 7, so that the first switching gear 411 is separated from the driving wheel 7, and the second switching gear is engaged with the driving wheel 7; when the second switching gear rotates in the opposite direction, the second protrusion will contact the second blocking portion 614, and the switching handle 62 rotates in the direction away from the second driven wheel group 51, and the second concave arc surface 613 of the switching lever 61 contacts the second limiting column 52, which is used to prevent the second rotating clamp from approaching the driving wheel, so that the second switching gear is separated from the driving wheel 7, and the first switching gear 411 is engaged with the driving wheel 7.The first switching gear 411 and the extrusion base 12 are both provided with a first tension spring column 122, and the second switching gear and the extrusion base 12 are both provided with a second tension spring column 123. A first spring 1221 is connected between the first switching gear 411 and the two first tension spring columns 122 of the extrusion base 12, and a second spring 1231 is connected between the second switching gear and the two second tension spring columns 123 of the extrusion base 12. When the switching handle 62 is in the initial state, the two ends of the switching rod 61 are respectively in contact with the first limiting column 42 and the second limiting column 52, so that the first driven wheel group 41 and the second driven wheel group 51 are separated from the driving wheel 7, and the first extrusion bearing 41 of the first driven wheel group 41 is 3 and the driving wheel 7 form a first feeding channel 30, with the first feed pipe 8 and the first discharge pipe 9 located at either end of the first feeding channel 30. The space separating the second extrusion bearing and the driving wheel 7 forms a second feeding channel 40, with the second feed pipe 10 and the second discharge pipe 20 located at either end of the second feeding channel 40. When the switching handle 62 is rotated toward the first driven wheel assembly 41, the first switching gear 411 of the first driven wheel assembly 41 engages with the driving wheel 7. When the switching handle 62 is rotated toward the second driven wheel assembly 51, the second switching gear of the second driven wheel assembly 51 engages with the driving wheel 7. The output shaft of the motor 3 can be controlled to rotate forward or backward. Specifically, the principle of automatic material change achieved by this device is as follows:

[0038] One end of the first rotating clamp 4 and the second rotating clamp 5 are both hinged to the extrusion base 12, and the other end is connected by a tension spring 43. Therefore, the tension spring 43 will apply a pulling force to the first rotating clamp 4 and the second rotating clamp 5 to move them together. When the switching handle 62 is in the initial position (when the switching handle 62 is not rotated to the left or right), the two ends of the switching rod 61 are respectively abutted against the first limiting posts 42 and the second limiting posts 52 respectively provided on the first rotating clamp 4 and the second rotating clamp 5. Due to the abutment, the switching rod 61 can counteract the tension generated by the tension spring 43, so that when the switching handle 62 is in the initial position, the first driven wheel group 41 and the second driven wheel group 51 are both separated from the driving wheel 7, thereby forming a first feeding channel between the first extrusion bearing 413 of the first driven wheel group 41 and the driving wheel 7, and a second feeding channel is formed between the second extrusion bearing of the second driven wheel group 51 and the driving wheel 7. When loading, the filament is added to the feed pipe and passed through the feeding channel to complete the loading.

[0039] When the two feeding channels are loaded with materials, the 3D printing process can be started. Specifically, for example, to start the first feeding channel 30, it is necessary to rotate the switching handle 62 to rotate the switching rod 61 toward the second limiting column 52. After the rotation, the end of the switching rod 61 that was originally in contact with the first limiting column 42 is no longer in contact (the second limiting column 52 and the other end of the switching rod 61 are still in contact), but the two are separated. After the separation, the distance between the first extrusion bearing 413 of the first driven wheel group 41 and the driving wheel 7 is reduced due to the tension of the tension spring 43, and the motor 3 drives the driving wheel 7 to rotate forward, and the driving wheel 7 drives the first extrusion bearing 413 of the first driven wheel group 41 to move (because the first extrusion bearing 413 has two inner and outer rings, the first switching gear 411 of the first driven wheel group 41 is installed together with the inner ring of the first extrusion bearing 413. In fact, the driving wheel 7 drives the outer ring of the first extrusion bearing 413 of the first driven wheel group 41 to move, so the switching gear does not move. In addition, because the end of the switching rod 61 is an inwardly concave arc surface, the switching rod 61 will not hinder the forward rotation of the first driven wheel group 41), extruding the filament into the first discharge pipe 9, and then extruded from the nozzle after heating.

[0040] If it is detected that the first feeding channel 30 is out of material, the motor 3 will drive the driving wheel 7 to rotate in the opposite direction. When the driving wheel 7 drives the first extrusion bearing 413 of the first driven wheel group 41 to rotate in the opposite direction, the filament remaining in the first feeding channel 30 will be withdrawn (because after the filament is withdrawn, there is no filament between the first extrusion bearing 413 of the first driven wheel group 41 and the driving wheel, so that the first switching gear 411 of the first driven wheel group 41 is meshed with the driving wheel 7). After the filament is withdrawn, the driving wheel 7 drives the first switching gear 411 to move. When the first switching gear 411 moves, the first The protrusion 412 will contact the first blocking portion 612 on the switching lever 61, and the first protrusion 412 will force the switching lever 61 to move in a direction away from the first driven wheel group 41. The switching lever 61 will abut against the first limiting column 42. The switching lever 61 will provide a certain resistance to the first limiting column 42, preventing the first driven wheel group 41 from approaching the driving wheel 7, thereby separating the first switching gear 411 from the driving wheel 7. At the same time, the distance between the second driven wheel group 51 and the driving wheel 7 is shortened, thereby realizing automatic material change, eliminating the need for manual monitoring and material change, and having a high degree of automation, improving work efficiency, and saving labor costs. In addition, there are many ways to detect material shortage in the feeding channel. For example, a sensor can be set in the feeding channel to detect whether the feeding channel is short of material. When the sensor detects material shortage, the output shaft of the motor 3 is controlled to rotate in the opposite direction.

[0041] In addition, the first spring 1221 connected between the two first tension spring columns 122 and the second spring 1231 connected between the two second tension spring columns 123 can provide a switching gear restraining force to the driven wheel when the driven wheel is separated from the driving wheel 7, so that the driven wheel and the driving wheel 7 remain in a separated state.

[0042] Please refer to Figure 6 The extrusion base 12 is provided with a first fixing hole 124 for securing the first feed tube 8, a second fixing hole 125 for securing the first discharge tube 9, a third fixing hole 126 for securing the second feed tube 10, and a fourth fixing hole 127 for securing the second discharge tube 20. The first fixing hole 124 and the second fixing hole 125 are coaxially located, while the third fixing hole 126 and the fourth fixing hole 127 are coaxially located. A support plate 128 is also provided within the mounting cavity 121 for supporting the first and second feed tubes 8 and 10. The support plate 128 is provided with a first support hole 1281 adapted to the diameter of the first feed tube 8, and a second support hole 1282 adapted to the diameter of the second feed tube 10. The first support hole 1281 and the second support hole 1282 are arranged side by side.

[0043] In some embodiments, such as this embodiment, see Figure 1 、 2 The device also includes a motor mounting plate 2; the motor mounting plate 2 is fixed to the bottom of the extrusion base 12, and the motor 3 is fixedly connected to the motor mounting plate 2.

[0044] Example 2

[0045] The present invention also provides an automatic material changing method for an automatic material changing device of a 3D printer. The method adopts the automatic material changing device of the 3D printer of the first embodiment. Specifically, the method comprises the following steps:

[0046] Step 1: Monitor the feeding channel in progress;

[0047] Step 2: Determine whether the feeding channel in operation is broken;

[0048] Step 3: If so, the motor is controlled to drive the driving wheel to rotate in the opposite direction to withdraw the residual wire in the feeding channel, and under the force of the driven wheel corresponding to the feeding channel on the switching rod, the driven wheel group corresponding to the feeding channel is separated from the driving wheel, so that the distance between the driven wheel and the driving wheel corresponding to the other feeding channel is shortened; if not, continue to execute the first step.

[0049] By monitoring the feeding channel, when a material break occurs, the reverse rotation of the motor is used to automatically switch the feeding channel, thereby completing automatic material change. There is no need for manual monitoring and material change. The degree of automation is high, which improves work efficiency and saves labor costs.

[0050] The above examples are merely provided to further illustrate the technical content of the present invention for easier understanding by the reader, but do not limit the embodiments of the present invention to these examples. Any extension or re-creation of the technology based on the present invention is protected by the present invention. The scope of protection of the present invention shall be determined by the claims.

Claims

1. 3D printer automatic material changing device, characterized in that, The invention comprises a cover body, an extrusion mechanism, a switching mechanism, a motor, a first feed pipe, a second feed pipe, a first discharge pipe and a second discharge pipe; a mounting cavity is provided in the cover body, and the extrusion mechanism and the switching mechanism are both mounted in the mounting cavity; the extrusion mechanism comprises a driving wheel, a first driven wheel group, a second driven wheel group, a first rotating clamp, a second rotating clamp and a tension spring; one end of the first rotating clamp and the second rotating clamp are both hinged to the cover body, and the other end of the first rotating clamp and the second rotating clamp are connected by the tension spring; the driving wheel is located between the first rotating clamp and the second rotating clamp; the output shaft of the motor is connected to the driving wheel; the switching mechanism comprises a switching rod rotatably connected to the cover body, and a switching handle fixedly connected to the switching rod; the end of the first rotating clamp close to the tension spring is fixedly connected to the first limiting column, and the end of the second rotating clamp close to the tension spring is fixedly connected to the second limiting column; when the switching handle rotates toward the first driven wheel group, the first driven wheel group meshes with the driving wheel, and when the switching handle rotates toward the second driven wheel group, the second driven wheel group meshes with the driving wheel Meshing; the first driven wheel group includes a first switching gear and a first extrusion bearing; the first switching gear is installed above the first extrusion bearing, and the first switching gear is provided with a first protrusion; the second driven wheel group includes a second switching gear and a second extrusion bearing; the second switching gear is installed above the second extrusion bearing, and the second switching gear is provided with a second protrusion; when the driving wheel meshes with the first switching gear and drives the first switching gear to rotate, the first switching gear drives the first protrusion to rotate and contact the switching rod, so that the switching rod moves away from the first switching gear and abuts the first limiting post, thereby causing the second switching gear to approach the driving wheel; one end of the switching rod is provided with a first concave arc surface, the first concave arc surface constitutes a guide surface abutting the first limiting post; the other end of the switching rod is provided with a second concave arc surface, the second concave arc surface constitutes a guide surface abutting the second limiting post; the first feed pipe and the first discharge pipe are respectively located at two ends between the first driven wheel group and the driving wheel, and the second feed pipe and the second discharge pipe are respectively located at two ends between the second driven wheel group and the driving wheel.

2. The automatic material changing device for a 3D printer according to claim 1, characterized in that: One end of the switching rod is further provided with a first blocking portion, and the other end of the switching rod is further provided with a second blocking portion.

3. The automatic material changing device for a 3D printer according to claim 1, characterized in that: The cover body includes an extrusion base and an extrusion cover connected to the extrusion base; the mounting cavity is provided on the extrusion base, and the extrusion base is provided with a through hole. The motor is fixed to the bottom of the extrusion base, and the output shaft of the motor passes through the through hole and is connected to the driving wheel.

4. The automatic material changing device for a 3D printer according to claim 3, characterized in that: The first switching gear and the extrusion base are both provided with a first tension spring column, the second switching gear and the extrusion base are both provided with a second tension spring column, a first spring is connected between the two first tension spring columns of the first switching gear and the extrusion base, and a second spring is connected between the two second tension spring columns of the second switching gear and the extrusion base.

5. The automatic material changing device for a 3D printer according to claim 3, characterized in that: The extrusion base is provided with a first fixing hole for fixing the first feed pipe, a second fixing hole for fixing the first discharge pipe, a third fixing hole for fixing the second feed pipe, and a fourth fixing hole for fixing the second discharge pipe; the first fixing hole and the second fixing hole are located on the same axis, and the third fixing hole and the fourth fixing hole are located on the same axis; a support plate for supporting the first feed pipe and the second feed pipe is also provided in the mounting cavity, and a first support hole adapted to the diameter of the first feed pipe and a second support hole adapted to the diameter of the second feed pipe are provided on the support plate; the first support hole and the second support hole are arranged side by side.

6. The automatic material changing device for a 3D printer according to claim 5, characterized in that: It also includes a motor mounting plate; the motor mounting plate is fixed to the bottom of the extrusion base, and the motor is fixedly connected to the motor mounting plate.

7. An automatic material changing method using the automatic material changing device of a 3D printer according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: Monitor the feeding channel in progress; Determine whether the feeding channel in operation is broken; If so, the motor is controlled to drive the driving wheel to rotate in the opposite direction to withdraw the residual wire in the feeding channel, and under the force of the driven wheel group corresponding to the feeding channel on the switching rod, the driven wheel group corresponding to the feeding channel is separated from the driving wheel, and the driven wheel group corresponding to the other feeding channel is engaged with the driving wheel.

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