562 detects the filament enters into the first guiding component 53, the first detector 561 starts to detect the position of the slidable component 551. When the first detector 561 detects that the slidable component 551 is moved away from the material outlet end 512, it represents that the length of the filament in the filament buffering device 50 reaches the maximum. At this moment, the first detector 561 transmits signal to the controller 563 to stop the operation of the filament driver (not shown), thereby reducing the risk of fracturing the filament caused when providing too much filament. When the first detector 561 detects the slidable component 551 is moved to be close to the material outlet end 512, it represents that the length of the filament in the filament buffering device 50 reaches the minimum. At this moment, the controller 563 controls the filament driver to speed up, thereby preventing the risk of breaking the filament caused when providing too less filament.

The side cover 52 is disposed at one side of the first guiding component 53 located farther away from the casing 51, and the side cover 52 is fixed to the casing 51 via bolts. Each of the side cover 52 and the casing 51 has an observation hole W for observing the position of the slidable component 551. The position of the slidable component 551 can be observed through the observation hole W, thereby rapidly determining the operation of the filament driver.

In this embodiment, the flexible first guiding component 53 and the second guiding component 54 enable the filament to be guided to the material outlet end 512 by the first guiding component 53 and the second guiding component 54 after the filament enters into the filament buffering device 50 from the material inlet end 511. The first guiding component 53 is slidable relative to the second guiding component 54, such that when the filament is provided too much, the first guiding component 53 may be deformed so as to slide relative to the second guiding component 54, and thus a part of the filament can be stored in the filament buffering device 50, thereby solving the possible issue of fracturing the filament during the 3D printing process.

The following descriptions will illustrate the operation of the filament buffering device 50 during the printing process. When the printing starts, the first guiding component 53 is filled with the filament from the storage box 60. The filament is continuously delivered while one end of the first guiding component 53 is driven to move away from the guide portion 541, such that the filament in the first guiding component 53 can be pushed and stored in the guide portion 541 for preventing the accumulation of the filament, thereby providing the buffering effect to the filament. When the guide portion 541 is full of the filament, the storage box 60 stops delivering the filament to the filament buffering device 50, and the buffering assembly 55 drives one end of the first guiding component 53 to move towards the guide portion 541 so as to push the stored filament to the nozzle 30. After the filament in the guide portion 541 is finished to be delivered, the storage box 60 delivers the filament into the first guiding component 53 again while one end of the first guiding component 53 is driven to move away from the guide portion 541 for filling the filament into the guide portion 541. As a result, the back and forth movement of the first guiding component 53 in the guide portion 541 can achieve a dynamic balance between the storage and delivering of the filament.

During the practical printing process, the filament delivering of the storage box 60 and the filament printing of the nozzle 30 are performed simultaneously, and the printing speed of the nozzle 30 may be varied according to the printing object. When the filament delivering speed of the storage box 60 is greater than the filament printing speed of the nozzle 30, the cooperation of the guide portion 541 and the first guiding component 53 can provide the buffering effect for the delivering of the filament, thereby preventing the filament from accumulating in the nozzle 30 and blocking the nozzle 30. If the filament printing speed of the nozzle 30 is increased, the filament stored in the first guiding component 53 and the guide portion 541 can provide to the nozzle 30 to perform printing. The guide portion 541 is, for example, a recess to cooperate with the first guiding component 53 for enabling one end of the first guiding component 53 to be movable along the guide portion 541. In another embodiment, the guide portion 541 may be a round channel, and the length of the guide portion 541 may be modified according to actual requirements.

A detector may be provided on the buffering assembly 55 for detecting the position of the first guiding component 53. When the first guiding component 53 is moved to a first predetermined position, one end of the first guiding component 53 is moved to a position in the guide portion 541 located farthest away from the second joint 58; that is, the amount of the filament stored in the guide portion 541 reaches the maximum, and the storage box 60 stops delivering the filament to be printed to the filament buffering device 50. Since the nozzle 30 continuously prints the filament, the buffering assembly 55 drives one end of the first guiding component 53 to move towards the guide portion 541; that is, the first guiding component 53 is moved from the first predetermined position to a second predetermined position, thereby providing the filament to the nozzle 30 to perform printing. When the first guiding component 53 is moved to the second predetermined position, one end of the first guiding component 53 is moved to a position in the guide portion 541 located closest to the second joint 58; that is, the filament in the guide portion 541 is depleted. The storage box 60 starts to deliver the filament to be printed to the first guiding component 53 of the filament buffering device 50 again, and the first guiding component 53 pushes the filament into the guide portion 541 while moving from the second predetermined position to the first predetermined position. Note that the first guiding component 53 can be moved back and forth between the first predetermined position and the second predetermined position so as to adjust the position of one end of the first guiding component 53 in the guide portion 541, thereby adjusting the buffering length to the filament, and thus achieving the stable delivering of the filament.

In a specific embodiment, the first guiding component 53 may be a straight pipe or a U-shaped pipe, preferably the U-shaped pipe. One end of the U-shaped pipe has a filament inlet which is located at one end of the U-shaped pipe and communicates with the outlet of the storage box 60. Another end of the U-shaped pipe is movably connected to the guide portion 541, and one end of the guide portion 541 located farther away from the U-shaped pipe is provided with a filament outlet which communicates with the nozzle 30.

The second guiding component 54 has a protective portion 542, and the protective portion 542 is located at one end of the guide portion 541 farther away from the first guiding component 53. The guide portion 541 is connected to the nozzle 30 via the protective portion 542, and the filament is delivered to the nozzle 30 through the protective portion 542. When the first guiding component 53 is moved to the second predetermined position, the filament in the guide portion 541 is depleted. At this moment, the storage box 60 replenishes the filament into the first guiding component 53 and the guide portion 541. In order to prevent the filament from breaking, the filament remained in the protective portion 542 is delivered to the nozzle 30 to perform printing. After the guide portion 541 receives the filament, the aforementioned processes are performed again, thereby ensuring the consistency of the printing and improving the 3D printing quality.

As shown in FIG. 4, the nozzle 30 includes a heater 31 and an extrusion device 32. The extrusion device 32 is connected to the filament buffering device 50 for delivering the filament to the heater 31. Specifically, the spools 61 of the storage box 60 stores the filaments with different colors, and the filaments can be delivered to the nozzle 30 through the filament buffering device 50. The nozzle 30 has the extrusion device 32 for receiving the filaments and delivering the filaments to the heater 31 to perform printing. In some embodiments, the extrusion device 32 may have a filament detector (not shown) for detecting the filament. The filament detector can detect whether the filament is the correct filament to be printed for preventing the extrusion device 32 from receiving the wrong filament, thereby ensuring the printing quality.

The 3D printer 1 may further include a cutting tool 70 and a main controller 80. The cutting tool 70 is disposed between the nozzle 30 and the filament buffering device 50 for cutting the filament. The main controller 80 is electrically connected to the cutting tool 70 and the storage box 60. The main controller 80 is configured to drive the cutting tool 70 to cut the filament according to a color change command, and is configured to drive the storage box 60 to deliver or retrieve the filament according to the printing command or the color change command. Specifically, when receiving the printing command, the main controller 80 drives the storage box 60 to deliver the filament to be printed on the corresponding spool 61 to the filament buffering device 50. When receiving the color change command; that is, the filament is finished to be printed, the main controller 80 drives the cutting tool 70 to cut the filament and drives the spool 61 of the storage box 60 to retrieve the cut filament from the filament buffering device 50 and wind it thereon, thereby improving the utilization of the filament and reducing the cost of 3D printing process.

The filament delivering speed of the storage box 60 may be greater than the filament delivering speed of the extrusion device 32. Preferably, the filament delivering speed of the spool 61 of the storage box 60 may be three times of the filament delivering speed of the extrusion device 32, such that the storage box 60 can provide a sufficient amount of the filament to the extrusion device 32 and the heater 31 immediately, thereby ensuring the smooth operation of the 3D printer 1.

The printing process of the 3D printer 1 of this embodiment is specifically introduced as follow. When receiving the printing command, the spool 61 of the storage box 60 delivers the filament to be printed to the filament buffering device 50 through the outlet of the storage box 60. The filament buffering device 50 receives and stores the filament to be printed and delivers it to the extrusion device 32 of the nozzle 30. The extrusion device 32 detects the filament to be printed and moves it to the heater 31 of the nozzle 30 to perform printing according to a predetermined model. When receiving the color change command, the main controller 80 drives the cutting tool 70 to cut the filament. At this moment, the spool 61 retrieves the filament which is finished to be printed while the storage box 60 delivers another filament with different color to the filament buffering device 50, such that the nozzle 30 can perform printing with such filament.

The following paragraphs will introduce a multi-color printing method cooperated with the 3D printer 1 of this embodiment. Referring to FIG. 7, FIG. 7 is a flow chart of a multi-color printing method cooperated with the 3D printer in FIG. 1. The multi-color printing method includes:

A step S71: the filament to be printed is delivered from the storage box 60 to the nozzle 30 through the filament buffering device 50; and

A step 72: after the filament to be printed is finished to be printed, the storage box 60 retrieves this filament and delivers another filament with different color to the nozzle 30 through the filament buffering device 50.

Furthermore, the step S71 may include: the filament buffering device 50 receives the filament to be printed from the storage box 60. Specifically, the first guiding component 53 of the filament buffering device 50 receives the filament to be printed from the storage box 60, such that the filament to be printed is located in the first guiding component 53. Then, whether the amount of the filament to be printed in the filament buffering device 50 reaches the predetermined maximum value is determined. If no, the filament buffering device 50 keep receiving the filament to be printed from the storage box 60. If yes, the filament buffering device 50 stops receiving the filament to be printed from the storage box 60. Note that the predetermined maximum amount of the filament to be printed in the filament buffering device 50 is the amount of the filament which fully fills the first guiding component 53 and the guide portion 541 of the filament buffering device 50.

In some embodiments, after the step S71, a step may be performed to determine whether the nozzle 30 receives the filament to be printed. If yes, the nozzle 30 performs printing according to the predetermined model. If no, the nozzle 30 keep trying to receive the filament to be printed in a predetermined period of time. When the nozzle 30 still does not receive the filament to be printed after exceeding the predetermined period of time, the 3D printer is required to be maintained. After the maintenance of the 3D printer 1, the step S71 is performed again to deliver the filament to be printed from the storage box 60 to the nozzle 30 through the filament buffering device 50.

More specifically, after the filament to be printed is delivered to the nozzle 30 through the filament buffering device 50, the extrusion device 32 of the nozzle 30 receives the filament while the filament detector on the extrusion device 32 detects whether the extrusion device 32 accurately receives the filament and whether the received filament is the filament to be printed or not. If yes, the nozzle