KR20160099125A - The apparatus of the printing head in a 3-D printer - Google Patents

Abstract

The present invention relates to a printing head for a 3D printer comprising a printing head spraying a printing material as a nozzle, a driving section for controlling the movement and spraying of the printing head and a control section. The printing head further comprises a final spraying nozzle therein. When a filament made of a resin is inserted on the nozzle, the inserted filament is molten by a heater, and the molten resin is sprayed through the nozzle to carry out printing. And when then the control section detects nozzle blocking, a process including detection of nozzle blocking, interruption of filament insertion, and removal of the filament by reverse rotation, a process including displacement of a moving plate to a position wherein an iron core can be inserted to the nozzle, rotation of a guide wheel (45), insertion of an iron core, or a process including rotation of a guide wheel (46), insertion of an iron core (61) to a V-shaped tube (47), and insertion of an iron core (61) to the nozzle (44) is carried out. The V-shaped tube (47) has two inlet tubes and one outlet tube. Thus, when the nozzle is blocked during printing, it is possible to carry out printing continuously by removing nozzle blocking. In addition, when the nozzle is blocked after the completion of printing, the nozzle can be used continuously without disposal thereof. Even when an error occurs during a printing process, printing can be continued by resetting.

Description

[0001] The present invention relates to a printing apparatus,

The present invention relates to an apparatus for a printhead in a 3D (Dimensional) printer, and more particularly, to an apparatus for removing a clogging of a nozzle during clogging of a printhead in a printing process, The present invention relates to an apparatus of a printhead in a 3D printer capable of providing a structure.

3 D printer is a machine that draws a real three-dimensional shape based on a three-dimensional drawing made by a computer design program. If you have any design ideas, you can use plastic materials as well as 150 materials such as rubber, metal, It can be made into a real thing in a day. In the early days of the development of the 3D printer, the material limited to plastics was extended to nylon, metal, etc., and the output parts, which were only used for taking industrial samples, were developed into watches, shoes, mobile phone cases and automobile accessories. In fact.

In this method, there is a cutting type method of carving a large raw material mass using a blade, but it is disadvantageous in that it consumes a large amount of material in the working principle of chunk cutting, and it is difficult to produce an object like a cup or a pipe. In addition, the most frequently used method is the laminated type. The laminated type is a method of constructing a layer by stacking the medium. That is, in the case of a recent 3D printer, it refers to a stacking type method. In addition, the laminated type may be classified depending on the material.

In addition, there is a method in which a plastic material such as ABS is melted and injected from a nozzle to laminate, a method in which a thin powder material is applied to a field, a laser is selectively melted and hardened to form a product, and a thin powder material is applied to a field, And a method of hardening by spraying an adhesive. Recently, combustion test of a rocket engine part made with a metal 3D printer has been reported as a result of the development of technology.

However, there are still some manufacturing errors and many improvements. That is, the technology for increasing the efficiency in the lamination process must be continuously and continuously developed.

For example, one way to increase fabrication efficiency is to allow the binder to penetrate into the underlying layer to create interlayer bonding. U.S. Patent Nos. 6,375,874 and 6,416,850 disclose a method of forming a continuous cross-section until a final target is formed after the first cross-sectional portion is formed.

However, it is sometimes possible to block jet nozzles that distribute the binder material to dust or the like, thereby preventing the binder material from being dispensed or causing the binder material to be dispensed incorrectly.

Therefore, in order to solve such a problem, Korean Patent Laid-Open No. 10-2009-0014395 discloses "a three-dimensional printer powder processing system comprising a plurality of powder holding receptacles, a plurality of powder holding receptacles coupled to the plurality of powder holding receptacles, A multi-port valve in flow communication with a plurality of powder holding receptacles and a vacuum source; and a filtration system disposed between the vacuum source and the plurality of powder retaining receptacles, wherein the vacuum source comprises a multi- A powder handling system for delivering powder between powder retaining receptacles through a valve. To reduce the contamination of the 3D printer and the surrounding area by the spread of powder, and at the same time to recycle the powder for reuse, including means for transferring the powder from multiple sources to the powder dispenser while minimizing user intervention Provide means to improve.

However, the above-described technique does not provide a specific means for allowing the printing to be continued without returning to the disposal of the printed product when the nozzle is clogged or an error occurs. Accordingly, it is inevitable to develop a structure and a printing method of a print head that can solve the problem by eliminating the nozzle clogging, recover the ink even when an error occurs, and continue printing.

Korean Patent Publication No. 10-2009-0014395 (February 10, 2009)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems of the related art, and it is an object of the present invention to provide a structure and a printing method of a print head capable of returning without discarding a printed product when a nozzle is clogged or an error occurs, The purpose is to provide.

The above object is further achieved by a 3D printer including a print head for jetting a print material as a nozzle, a drive unit for controlling movement and injection of the print head, and a control unit, further comprising a nozzle for ultimately jetting a material in the print head, A filament made of a resin is inserted on a nozzle, the inserted filament is melted by a heater, and the melted resin is sprayed onto the nozzle and printed. When the nozzle clogging is detected by the controller, The guide wheel 45 is rotated to the position where the iron core can be inserted into the nozzle → the guide wheel 45 is rotated → the iron core is inserted or the guide wheel is rotated 46 → the iron core 61, (47), " inserting into the iron core (61) nozzle (44) ", wherein the "V" tube (47) 1 < / RTI >

In another embodiment of the present invention, there is provided a 3D printer including a print head for ejecting a print material as a nozzle, a drive unit for controlling movement and injection of the print head, and a control unit, And a first nozzle unit and a second nozzle unit, wherein the first nozzle unit and the second nozzle unit are formed by inserting a filament made of resin onto a nozzle, melting the inserted filament by a heater, and spraying and printing the molten resin with the nozzle, The first nozzle unit also has a nozzle 44, an extruder gear 41 and an extruder U-grooce guide wheel 42. The second nozzle unit also has a nozzle 44 ', an extruder gear 41' and an extruder U- The difference between the first nozzle portion and the second nozzle portion is the difference in the diameter of the nozzle, and the " thickness of the outer wall of the product and the thickness of the structure of the product according to the designed value of the program &The step of selecting one of the N nozzles → driving the selected nozzle "is performed by the control unit.

In addition, both the first nozzle portion and the second nozzle portion are further provided with an iron core 61 inserted into the nozzle and a guide wheel 45 (46) for moving the iron core to remove clogging of the nozzle.

When an error occurs, the control unit recognizes the coordinates of the position where the error occurs. If it is necessary to remove the nozzle clogging, the nozzle clogging process is performed. If the error is generated, The printing is restarted after positioning,

In addition, the recovery process after the error is corrected by applying a real-time control method so that the entire process can be performed, the coordinates (x, y, z) are sequentially recorded in a specific register of the control unit 20 of the equipment, , The motor is controlled by the coordinate value stored in the register and the recovery is performed.

On the other hand, a work table is provided with a porous table thereon, and the porous table is fixed by a work table and a fixing means.

As described above, in the apparatus and the printing method of the print head in the 3D printer, if the nozzle is clogged during printing, the clogging of the nozzle can be eliminated and printing can be continued, and even if the nozzle is clogged after the printing is finished, So that even if an error occurs in the printing process, the printing can be continued.

1 is a diagram of an embodiment showing a 3D configuration diagram to which an algorithm method of the present invention is applied.
Fig. 2 is a view showing an embodiment showing a process in which a material is injected and ejected.
3 is a diagram of an embodiment illustrating a method for solving nozzle clogging.
Figs. 4 to 6 are views showing embodiments in which the iron core is inserted into the nozzle. Fig.
FIGS. 7 and 8 are views of embodiments showing a method of performing recovery.
9 is a diagram of an embodiment showing a flow chart for performing a return process.
Figure 10 is an illustration of an embodiment for effective 3D printing.
Figs. 11 and 12 show the method of the embodiment which solves the problem that the product is separated from the work table due to insufficient adhesion of the work.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In other words, the following merely illustrates the principles of the present invention. Thus, those skilled in the art will be able to devise various apparatuses which, although not explicitly described or shown herein, embody the principles of the invention and are included in the concept and scope of the invention.

It is also to be understood that the detailed description, as well as the principles, aspects and embodiments of the invention, as well as specific embodiments thereof, are intended to cover structural and functional equivalents thereof.

In addition, when the conventional technology is applied to the description of the present invention, the detailed description of common technology can be omitted.

On the other hand, a method of manufacturing a 3 D printer widely used as a most recent method is a lamination type, and a lamination type is a method of literally forming a layer by stacking a medium. And, the laminated type may be distinguished according to the material.

ABS is a method of spraying plastic materials from nozzles and laminating them, a method of thinning the powder material in the field, a method of making the product by repeatedly melting the selected portion with the laser, and a method of laying the thin powder material on the field, There is a way of spraying and solidifying. Recently, combustion test of a rocket engine part made with a metal 3D printer has been reported as a result of the development of technology.

A 3D printer according to the present invention includes a device for processing a material, a drive control section for controlling the movement of the print head, a print head for automatically supplying a material used for 3D printing and ejecting a material as necessary, And an ejection control unit for controlling the ejection of the material in the print head. In addition, a general control unit for controlling the drive controller and the ejection controller by the programmed data is also included, and the drive controller and the ejection controller may include a motor have.

At this time, if necessary, a valve for controlling the movement and stop of the printing material may be further included.

1 is a diagram of an embodiment showing a 3D configuration diagram to which an algorithm method of the present invention is applied.

That is, FIG. 1 is a diagram showing a configuration of a 3 D printer in a stacked type, which is a 3D printer to which the algorithm of the present invention is applied. That is, a jetting device (or a printing head) 40 (a structure including a nozzle 44 and a heating box 43 in the present invention described later) for jetting a printing material as a nozzle or a printhead, A work table 50 in which a 3D shape is formed through printing of a drive unit 30 (including a motor 41d and a nozzle drive unit 44b in the present invention described later) for controlling the drive unit 30, And a general control section 20 and an interface section 10 in which path algorithms and the like are stored. The interface unit 10 is a device including a display unit, an input unit, and a communication unit capable of wired / wireless communication depending on the output unit.

In the present invention, the composition unit 30 may refer to an extruder gear 41 and an extruder U-grooce guide wheel 42. The extruder gear 41 and the motor for rotating the extruder U- (Although the motor is omitted in the present invention for the sake of convenience in the present invention, it means a general general power source for obtaining rotational power).

Fig. 2 is a view showing an embodiment showing a process in which a material is injected and ejected.

The extruder gear 41 and the extruder U-grooce guide wheel 42 interact with each other by the filament 60 (as a resin material in the form of a wire) as shown in the drawing, and the heating block 43 and the nozzle 44 are provided. Then, the filament 60 is melted by the heater provided in the heating block 43, and the molten filament is injected (60 ') through the nozzle in the form of liquid resin (ABS resin or general resin).

Although not shown in FIG. 2 of the present invention, a pressurizing pump, a screw motor, or a gear pump can be used to eject molten material. As such a blowing method, a normal blowing method can be used, and a normal blowing method is applicable to the present invention.

소재를 이동시킬 수 있는 역할을 하는 것으로서,

소재를 이동시킬 수 있는 역할을 한다면, 본원발명에 적용되는 기술 수단이 압출기 기어(41)와 압출기 U-grooce 가이드 휠(42)에 한정되지는 않는다.In addition, the extruder gear 41 and the extruder U-grooce guide wheel 42 are made of a wire-

As a function of moving the material,

The technical means applied to the present invention is not limited to the extruder gear 41 and the extruder U-grooce guide wheel 42, provided that it can move the material.

A nozzle for finally spraying a material in the print head is further included. A filament made of resin is inserted over the nozzle, the inserted filament is melted, and the molten resin is injected by the nozzle to be printed.

- Example 1 -

3 is a diagram of an embodiment illustrating a method for solving nozzle clogging.

That is, the present invention is a method of removing a clogged portion of a clogged nozzle when the clogged nozzle becomes clogged during a printing operation using a 3D printer. When the nozzle is clogged during the printing operation, the rotation of the extruder gear 41 and the extruder U-grooce guide wheel 42 is reversed to separate the filament 60 from the nozzle 44.

The separation process is performed by the control of the comprehensive control unit 20.

Quot; nozzle clogging ", " nozzle clogging detection ", " filament insertion stop ", " filament removal by reverse rotation ", is performed under the control of the control unit. Which will be described later in the present invention.

The "filament insertion stop" is to stop the driving of the motor that supplies power to the extruder gear 41 or the like, and the "filament removal by reverse rotation" reverses the rotation of the motor that provides power. And the algorithm of this control method can be used in the memory part and stored in the memory part.

On the other hand, when the step of "removal of the filament by reverse rotation" is performed, the wire-like iron core 61 is inserted into the nozzle to completely eliminate the cause of nozzle clogging.

That is, a filament made of a resin is inserted on a nozzle, the inserted filament is melted by a heater, and the melted resin is injected and printed by the nozzle, and when the nozzle is clogged, the filament is removed and the iron core is inserted into the nozzle .

Figs. 4 to 6 are views showing embodiments in which the iron core is inserted into the nozzle. Fig.

4 and 5 show the method of the embodiment in which the iron core 61 is inserted from the lower side of the nozzle 61. When the iron core 61 is inserted from the lower side of the nozzle as shown in Fig. 4, The resin is removed. At this time, the process of removing the clogging can be more effectively performed by heating the heater in the heating block 43.

In this case, a heater (which is omitted in the present invention, but refers to a heater that applies heat, while controlling the amount of power to be supplied to the heater, means a conventional heater capable of controlling the temperature by adjusting the amount of power supplied thereto. ) Is also performed by the control unit 20.

When the controller detects the "nozzle clogging" by a predetermined algorithm, the amount of current supplied to the heater is increased, resulting in further heating of the heater, and the temperature of the nozzle is also increased. The process of controlling the amount of current supplied to the heater is performed by the control unit 20 according to a predetermined algorithm stored in the memory unit.

At this time, the iron core is made of a metal material having elasticity, and the shape is a wire-like shape.

5, a moving plate 48 and an insertion tube 49 are provided at a position separate from the work table 50 on the lower side of the nozzle 44, and the lower side of the nozzle through the insertion tube 49 In which the iron core 61 can be inserted.

When the nozzle is clogged, the position of the nozzle 44 or the work table 50 is changed or positioned at the initial position (reset), and the moving plate 48 is moved so that the iron core 61 comes to a position where the iron core 61 can be inserted into the nozzle do. That is, the following steps are performed.

"Detecting clogging of nozzle → Remove filament → Move nozzle or work table (50) → Move iron plate to a position where it can be inserted into nozzle → Rotate guide wheel (45) → Insert iron core"

The filament removal is to remove the filament from the nozzle by reverse rotation as described in the previous embodiment, and the rotation of the guide wheel 45 means that the iron core is inserted into the nozzle, (45).

The power of the motor 48a is transmitted to the shaft 48c and the left or right movement or the up and down movement is determined by the direction changing box 48d. To the moving plate (48). At this time, the method of the left-right movement and the up-and-down movement may be applied to the present invention by using a normal movement method other than the embodiment of FIG.

5 is performed by the control unit 20 according to the algorithm stored in the memory unit.

Fig. 6 is a view of an embodiment showing how the iron core 61 is inserted from above the nozzle. As shown in Fig. 6, a "V" magnet tube 47 is used. The "V" -shaped tube (47) is a tube with two tubes for the inlet and one tube for the outlet. Therefore, both the filament 60 and the iron core 61 can be inserted from the inlet side through the "V" magnetic pipe 47, and only one of the filament 60 and the iron core 61 can be discharged from the outlet side .

Therefore, in order for the iron core 61 to be inserted into the "V" tube 47, the filament 60 must be removed. In order for the filament 60 to be inserted, the iron core 61 must be removed.

The process of solving the nozzle clogging by the method of FIG. 6 is as follows.

"Detecting the nozzle block → reverse rotation of the extruder gear 41 and the extruder U-grooce guide wheel 42 → removal from the filament 60" V "tube 47 → rotation of the guide wheel → rotation of the iron core 61" V "tube 47 → inserted into the iron core 61 nozzle 44"

In addition, the above-described process is performed by the control unit 20 according to the algorithm stored in the memory unit.

- Example 2 -

FIGS. 7 and 8 are views of embodiments showing a method of performing recovery.

There is a case where an error occurs in the process of printing using a 3D printer. If an error occurs, it is forced to discard the intermediate product that has been printed until then.

Generally, an error in the printing process is caused by an error in the program execution process and clogging of the material. An error in the program is an error in the execution of the computer program, and clogging of the material means that the material is clogged in the nozzle or heating box.

As a result, if the printing is stopped instantaneously due to the above-mentioned cause, the printing process can be continued by allowing the nozzle to be located at the position where the error occurs without discarding the printed intermediate product.

7 is a block diagram for sensing the speed of the motor. The extruder gear 41 and the extruder U-grooce guide wheel 42 are connected to the rotary shaft 41a and the power of the motor 41d is transmitted to the rotary shaft 41a through the transmission shaft 41c through the power distributor 41b . Here, the power distributor 41b is a distributor for driving two motive power as one power source. On the other hand, a method for driving gears and gears with a single motor can be applied using a conventional method.

At this time, the encoder 41e can be mounted on the motor to sense the speed or the rotation speed of the motor. The encoder 41e is connected to the control unit 20, and the control unit controls the speed or the rotation speed of the motor sensed by the encoder It can be judged whether it is in a state or an abnormal state.

The speed or the rotation speed of the motor is sensed, and when the rotation speed or speed is not the predetermined rotation speed or speed, it is determined as an error state, and the position coordinates of the error state are recognized. Then, the nozzle is positioned at the recognized coordinate point, and then the printing process is performed again.

The process of this algorithm is performed by the control unit by the algorithm stored in the memory unit.

8 is a diagram illustrating a method for detecting an error state by sensing a state of a nozzle. A sensor 44a may be attached to the nozzle 44 to sense the flow of the material in the nozzle and determine the steady state and the non-steady state. The sensor 44a is connected to the control unit.

9 is a diagram of an embodiment showing a flow chart for performing a return process.

When the 3 D printing is started, the nozzle 44 moves and the driving of the filament 60 is performed. At this time, the filament drive uses a step motor and performs 3-axis (x, y, z) control.

The speed of the extruder gear 41 for moving the filament is controlled so as to be related to the temperature of the heater. (S 100 - S 102)

When an error is generated by the above method, the coordinates of the position where the error occurs are recognized (S 104 -S 106). When the process of removing the nozzle clogging is required, the process of removing the nozzle clogging is performed. (S 108)

(S 110). In the meantime, the recovery process after the occurrence of the error is performed by the real-time control system (the whole process is performed) by performing the real-time control system To make it possible. The coordinates (x, y, z) are sequentially recorded in a specific register of the control unit 20 of the equipment, and the motor is controlled to recover the coordinate value stored in the register.

For example, if the position of the errored coordinate is (23, 44, 55), printing will start again at the position where the error occurred (23, 44, 55).

Then, printing progress and printing are completed (S 112)

If an error has not occurred in step 104, printing is continued and printing is completed. Then, the entire printing process is terminated (S 114)

On the other hand, the rotation speed of the motor is determined by the coordinate value, that is, the rotation speed may vary depending on the coordinate value. Therefore, the speed of the motor corresponding to the coordinate value is predetermined, It is detected as an error.

- Example 3 -

Figure 10 is an illustration of an embodiment for effective 3D printing.

The thickness of the outer wall or the product structure of the printed product may vary depending on the design structure of the product, but the thickness of the outer wall or structure of the product must be different even in the same product.

Therefore, if the diameter of the injected nozzles is consistently the same even if the thicknesses are different from each other, it becomes inefficient to print. Therefore, at least two or more (possibly up to five) print heads having different nozzle diameters may be prepared, and nozzles corresponding thereto may be selected according to the thickness,

10, a nozzle 44, an extruder gear 41 and an extruder U-grooce guide wheel 42 are also provided in the first nozzle portion, and a nozzle 44 ', an extruder gear 41' ) And an extruder U-grooce guide wheel 42 '.

Although not shown in FIG. 10, both the first nozzle portion and the second nozzle portion may further include an iron core 61 and guide wheels 45 and 46. However, the motor 41d and the nozzle driving portion 44b may be included in the first nozzle portion and the second nozzle portion, or may be made in a structure not so.

The difference between the first nozzle portion and the second nozzle portion is a difference in diameter of the nozzle. That is, if the thickness of the outer wall of the product or the thickness of the structure is large, the nozzle having a large diameter is selected, and if the thickness of the outer wall of the product or the thickness of the structure is small, the nozzle having a small diameter is selected. This method is performed under the control of the control unit 20 by an algorithm stored in the memory unit. That is, when the control unit selects and drives the motor 41d and the nozzle driving unit 44b of the first nozzle unit, the first nozzle unit is driven, and the controller selects the second nozzle unit motor 41d 'and the nozzle driving unit 44b' The second nozzle portion is driven.

Then, this process goes through the following selection process.

"Determine the thickness of the outer wall of the product and the thickness of the structure by the designed value in the program → choose one of the second nozzle or the Nth nozzle → drive the selected nozzle"

When the thickness of the outer wall of the product and the thickness of the structure are determined according to the values designed in the program, the coordinate values can be grasped together. In other words, the nozzle can be selected differently depending on the thickness of the same product.

For example, if the thickness of the wall is 5 mm and the coordinates are (2.0, 1.0, 1.0) to (1.0, 1.0, 1.5) from the coordinates (1.0, 1.0, 1.0) When the thickness of the wall is 12 mm,

A nozzle with a diameter of 0.8 mm was used from the coordinates (1.0, 1.0, 1.0) to (1.0, 1.0, 1.5) and a nozzle having a diameter of 1.0 mm The nozzle is used.

In this case, if the first nozzle is a nozzle having a diameter of 0.8 mm, the first nozzle is used from (1.0, 1.0, 1.0) to (1.0, 1.0, 1.5) , 1.0, 1.5), the second nozzle can be used.

Example 4 -

Figs. 11 and 12 show the method of the embodiment which solves the problem that the product is separated from the work table due to insufficient adhesion of the work.

11 is an actual photograph showing the material being separated on the actual work table (or the build plate). When the product is separated from the work table 50 as shown in FIG. 11, .

Usually, the cause of the above-mentioned separation defect is as follows: "Insufficient adhesion between the build plate and the material, heat shrinkage during the curing process of the molten material, insufficient build plate temperature, and other environmental influences (temperature, humidity, etc.) However, since this problem is not inherently solved, there are other ways to find a solution.

12 is a view of an embodiment for solving the problem of spacing failure. That is, a porous plate 51 is mounted on the top of the self-standing table 50, and a 3 D printing operation is performed on the porous plate 51.

Then, the material (molten resin) seeps into the pores of the porous plate 51 (small space in the porous plate), and the resultant material of the 3 D printing sticks to the porous plate, .

Since it is necessary to fix the porous plate 51 and the work table 50, the porous plate and the work table are fixed by fixing means 52 such as a screw. In this case, in the present invention shown in FIG. 12, a method of fixing a work table and a fixing method between porous plates in a screw shape using grooves has been proposed. Practically, a general method of fixing a porous plate to a work table is also described in the present invention Can be applied.

10: interface unit 20: general control unit
30: driving part 40: print head (ejecting device)
41: extruder gear 42: extruder U-grooce guide wheel
43: Cartridge heater 44: Nozzle
45: Guide wheel 46: Guide wheel
47: V-shaped tube 48; Moving plate
49: insertion tube 50: work table
60: Material (filament) 61: iron core
51: porous plate 52: engaging means

Claims (6)

In a 3D printer including a print head that ejects a print material as a nozzle, a drive unit that controls movement and ejection of the print head, and a control unit,
Further comprising a nozzle for ultimately ejecting a material in the print head,
A filament made of a resin is inserted over the nozzle, the inserted filament is melted by a heater, the molten resin is injected by the nozzle and printed,
If the nozzle clogging is detected by the control unit, the steps of "nozzle clogging detection → filament insertion stop → filament removal by reverse rotation"
"Move the moving plate to the position where the iron core can be inserted into the nozzle → Rotate the guide wheel 45 → Insert the iron core" or "Rotate the guide wheel 46 → Insert the iron core 61 into the" V "magnetic pipe 47 → Insert the iron core 61 ) ≪ / RTI > into the nozzle 44,
Wherein the "V" tube (47) is a tube having a shape in which two tubes serve as an inlet and one tube serves as an outlet. In a 3D printer including a print head that ejects a print material as a nozzle, a drive unit that controls movement and ejection of the print head, and a control unit,
Further comprising a nozzle for ultimately ejecting a material in the print head,
A filament made of a resin is inserted over the nozzle, the inserted filament is melted by a heater, the molten resin is injected by the nozzle and printed,
Grooved guide wheel 42 and a nozzle 44, an extruder gear 41 and an extruder U-grooce guide wheel 42 are also provided in the first nozzle portion, and the nozzle 44 ', An extruder gear 41' and an extruder U-grooce guide wheel 42 '
The difference between the first nozzle portion and the second nozzle portion is the difference in diameter of the nozzle,
The step of selecting one of the second nozzle or the N < th > nozzle to drive the selected nozzle is performed by the control unit. Of the device. 3. The apparatus of claim 2, further comprising an iron core (61) inserted into the nozzle to remove clogging of the nozzle in both the first nozzle unit and the second nozzle unit, and guide wheels (45, 46) for moving the iron core A feature of the apparatus of the printhead in a 3D printer. 2. The method according to claim 1, wherein, when an error occurs in the controller, the coordinate of the position where the error occurs is recognized. When the process of removing the nozzle clogging is required, the nozzle clogging process is performed, So as to perform a function of restarting printing after the nozzles are repositioned to the printing head. 2. The method according to claim 1, wherein the recovery process after the error is corrected by applying a real-time control method so that the entire process can be performed, and the coordinate (x, y, z) And the controller controls the motor to a coordinate value stored in the register and proceeds to the recovery. The apparatus of claim 1, wherein the work table is provided with a porous table thereon, and the porous table is fixed with a work table and fixing means.

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