KR102251338B1 - 3D printing color change multi-nozzle system - Google Patents

Abstract

The present invention relates to a color change multi-nozzle system for a 3D printer. More specifically, in a 3D printer that produces a predetermined three-dimensional object in full color, while one of a plurality of molten filaments with different colors is selectively injected, the quality of an output due to a filament remaining in a nozzle is prevented and production time is reduced. The color change multi-nozzle system comprises: a body part; and a plurality of filament supply units configured to insert and withdraw filaments of different colors from the body part. The body part comprises: a heating block configured to apply heat to the filaments; a plurality of material inlet units coupled to the heating block and configured to introduce filaments from the filament supply units; a plurality of material outlet units formed at the lower end of the heating block to communicate with the material inlets, respectively; and a nozzle part disposed so as to be in contact with the lower end of the heating block and formed so that an ejection hole penetrates vertically. When one of the material outlet units is positioned to communicate with the ejection hole by moving the nozzle part, all material outlet units other than the communicating material outlet units are configured to be blocked.

Description

3D printing color change multi-nozzle system {3D printing color change multi-nozzle system}

The present invention relates to a color changing multi-nozzle system of a 3D printer, and more particularly, in a 3D printer that produces a predetermined three-dimensional object in full color, while selectively injecting one of a plurality of molten filaments having different colors, The present invention relates to a color change multi-nozzle system for 3D printers that prevents deterioration of print quality due to the filaments remaining in the nozzle and reduces production time.

In general, there are various types of 3D printers that produce a predetermined three-dimensional object according to a method of manufacturing a three-dimensional object, among which the FDM (Fused Deposition Modeling) method is one of the most widely used 3D printing methods today. FDM generates a computer control signal based on a 3D drawing made by a computer program and transmits this data to a 3D printer to move the 3D printer head. And the molten material (a filament material such as ABS plastic, PLA, etc.) is sprayed according to the control signal from the nozzle of the 3D printer head, and the sprayed molten material is laminated on the flat structure. After that, a three-dimensional object is created through a cooling process, and this three-dimensional structure is characterized by a parallel pattern appearing on a planar structure by lamination.

In the FDM (Fused Deposition Modeling) method as described above, in the case of forming a colorful three-dimensional object instead of a single color, it has to be molded into a filament of one color and then replaced with a filament of a different color. The method of printing by changing the nozzle of the corresponding color according to the color value of the data set by using the nozzle of and by injecting filaments of different colors alternately into the nozzle whenever the output color is changed using one nozzle. There was a way to extrude.

In the case of the method using a plurality of nozzles, the process of replacing the color requires replacing the supply pipe of the color being worked on with a filament supply pipe of a different color and connecting it to the heater nozzle or transferring the heating nozzle itself. It takes a considerable amount of time to replace the filament, and the molten part that has already been formed is hardened during the waiting time for the replacement of the filament. Due to poor adhesion of the product, the appearance or integrity of the product decreases, or the separation of materials or structural strength decreases, and there is a problem. In addition, in the process of replacing the nozzle, the molten filament flows down and other colors are mixed in a place other than the designated colored part, thereby deteriorating the coloring quality.

In the method of using one nozzle, the solid filament is transferred to the heating block and the molten filament is extruded with the nozzle, but when the color is changed, the process of removing the existing color residues inside the heating block and in the nozzle. It is necessary, and for this purpose, a method of forming a structure called a prime tower is used, in which the remnants are extruded and stacked at a separate location. However, the method of forming a prime tower to treat residues has disadvantages that material waste is severe and the printing time is lengthened (refer to the drawing).

In addition, the output quality of a 3D printer is that delicate printing is possible as the thickness of each layer of the 3D model decreases, so the quality of the printout increases, but it takes a lot of time to print. While the quality is lowered, the printing time is shortened.

Therefore, in order to increase the quality of the printout, it is necessary to print while changing the size of the nozzle, and to change the size of the nozzle, it is necessary to perform work while replacing and installing nozzles having different ejection ports. However, there is a disadvantage in that the replacement is difficult and the printing time is lengthened because the remnant must be removed and replaced in the process of replacing the nozzle.

In the case of the'multi-color nozzle for 3D printer' of Patent Document 1, "It is made in a tubular shape, and a filament material melted therein is mixed, and a coupling part having a plurality of melting member insertion holes and connection member coupling holes is formed at the top. , At the bottom, a body with an extruded member through which the melt-blended filament material is extruded; A heater block mounted on the outer circumferential surface of the body to supply heat of a predetermined temperature; A heater for melting filament materials on the outer circumferential surface of the tubular shape” is included, and in more detail, filaments of various colors are mixed in the body, and the filament materials of each color are inserted through the material insertion hole at the top of the body. The invention is configured to be melt-supplied into the interior and inject it into the extruded member at the bottom, and the invention may cause the quality of the manufactured molding to be unsatisfactory because the filaments cannot be perfectly mixed with each other in the process of melting the filaments, Compared to the method of stacking colors by stacking unmixed primary color filaments, there is a problem in that the color is not clear.

Accordingly, there is a growing need for a nozzle system that injects filament materials of various colors while using a single nozzle to reduce manufacturing cost and has a high printing speed.

Domestic patent registration No. 10-1833902

Accordingly, the present invention has been devised to improve the conventional problems as described above, and is configured to output multiple colors with one nozzle in an FDM type 3D printer that outputs a shape by melt extrusion of a filament material. , When printing filaments with various colors in sequence, the melted filament flows down to prevent mixing when printing filaments of different colors, and the diameter of the ejection port is easily changed to improve the quality and printing speed of the printout. It is to provide a printing color change multi-nozzle system.

In order to solve the above-described problems, the present invention provides a "body part; And a plurality of filament supply units configured to input and output filaments of different colors to the body unit, wherein the body unit includes a heating block configured to apply heat to the filament, the heating block is coupled to the heating block, and the filament is introduced from the filament supply unit. A plurality of material inlet portions configured to be configured, a plurality of material outlets formed at the lower end of the heating block to communicate with the plurality of material inlet portions, and a nozzle portion disposed to be in contact with the lower end of the heating block and formed to penetrate the ejection port vertically. 3D printing color change multi-nozzle system configured to block all material outlets other than the communicated material outlets when one of the plurality of material outlets is positioned to communicate with the ejection port by moving the nozzle unit. Provides.

In addition, a central axis extending upward from the center of the nozzle unit and formed to penetrate the heating block vertically; And a step motor coupled to an upper end of the central axis; wherein the plurality of material outlets are disposed at equal intervals from the center of the central axis toward the outer side, and any one of the material outlets is rotated by rotating the nozzle unit. It may be characterized in that it is configured to communicate with the ejection port.

In addition, the body portion may be characterized in that it is configured to be movable along the X-Y axis on a plane.

In addition, the nozzle unit may be configured such that an upper end of the ejection port communicates with any one of the plurality of material discharge ports, and the lower end of the ejection port is configured to converge toward the center of the nozzle unit.

In addition, the nozzle portion may be formed in a plurality of the ejection orifices to have different diameters, and the nozzle portion may be rotated to communicate any one of the ejection orifices with any one of the plurality of material discharge ports. .

In addition, a thread formed along the outer circumferential surface of the central axis; A bearing disposed to be in contact with an upper end of the heating block; A spring disposed to be in contact with the upper end of the bearing; And an adjustment nut disposed to be in contact with the upper end of the spring; wherein the central axis passes through the heating block, the bearing, the spring, and the adjustment nut in sequence, and fastens the adjustment nut to the thread. It may be characterized in that it is configured to.

According to the present invention made as described above, since it is possible to output various colors to one nozzle by sequentially outputting filaments of various colors through one nozzle, space utilization is higher than that of a method having a plurality of nozzles. It increases and has the effect of reducing the manufacturing cost.

In addition, in the present invention, the molten filament remaining in the nozzle is retracted when the color is changed, so that continuous printing is possible without the creation of a prime tower, thereby reducing material cost and enabling color printing at high speed.

In addition, the present invention blocks the flow of filaments other than the output filaments to prevent deterioration in the quality of the printout due to the mixing of colors, and the diameter of the ejection port can be changed to a desired size at any time, so that precise output is achieved without deteriorating the print speed. There is an effect that becomes possible.

In addition, according to the present invention, the structure of the nozzle is relatively simple and the color and the diameter of the ejection port can be changed quickly with a single nozzle, thereby reducing maintenance and manufacturing costs.

1 is a conceptual diagram of a 3D printing color changing multi-nozzle system according to the present invention.
Figure 2 is a conceptual diagram showing a color change process by changing the position of the ejection orifice according to the present invention.
Figure 3 is an exploded perspective view showing a 3D printing color changing multi-nozzle system according to the present invention from the bottom.
Figure 4 is an exploded perspective view showing in more detail the noble and central axis of the 3D printing color changing multi-nozzle system according to the present invention.
Figure 5 is a front view showing a state in which the members of Figure 4 are combined.
Figure 6 is a flow chart showing a process of transferring the body portion to the XY axis.
7 is a conceptual diagram showing a nozzle structure capable of changing the color without changing the exit position of the ejection port.
Figure 8 is a bottom view of the 3D printing color change multi-nozzle system according to the present invention.
9 is a reference diagram showing the structure of an existing nozzle.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to elements of each drawing, the same elements are assigned the same numerals as possible even if they are indicated on different drawings. In addition, in describing an embodiment of the present invention, if it is determined that a detailed description of a related known configuration or function interferes with the understanding of the embodiment of the present invention, the detailed description thereof will be omitted.

In addition, in describing the constituent elements of an embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the nature, order, or order of the component is not limited by the term. When a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected or connected to that other component, but another component between each component May be “connected”, “coupled” or “connected”.

Hereinafter, a 3D printing color changing multi-nozzle system as an example of the present invention will be described in detail with reference to FIGS. 1 to 9.

Referring to FIG. 1, the body part 100 and the body part 100 comprise a plurality of filament supply parts 200 configured to input and output filaments of different colors, respectively, wherein the body part 100 is a filament A heating block 110 configured to apply heat to the heating block 110, a plurality of material lead-in portions 120, a plurality of material lead-in portions 120 coupled to the heating block 110 and configured to lead a filament from the filament supply portion 200 A plurality of material outlets 140 formed at the lower end of the heating block 110 so as to communicate with each other, and a nozzle portion formed to be in contact with the lower end of the heating block 110 and to allow the ejection port 151 to penetrate vertically ( 150); may include.

3D printing color change multi-nozzle system according to an example of the present invention may be configured to include a body portion 100, a filament supply portion 200, and a filament spool (Filament spool) 300. Filament spool (300) is a material of filament is wound and a plurality of filament spools (Filament spool) 300 having different colors can be arranged, each unwound from the filament spool (Filament spool) (300) Each of the filaments may be introduced into the body part 100 through the filament supply part 200.

The body portion 100 may be configured to move along the X-Y axis on a plane by being combined with a transfer device (not shown). In addition, the body portion 100 may be configured to move in the X-Y-Z axis direction or the bottom plate to move in the Z axis direction.

The filament supply unit 200 may be configured such that a pair of rollers 210 are disposed therein and the filament moves forward or backward according to the rotation of the roller 210. In addition, the filament supply unit 200 may be directly connected to the body unit 100 or may be disposed at a position spaced apart from the body unit 100 in a Bowden method.

The body portion 100 is a heating block 110, a plurality of material lead-in portion 120 coupled to the heating block 110, a plurality of material inlet portion 120 to communicate with each of the heating block 110 A plurality of material discharge ports 140 formed at the lower end, and a nozzle unit 150 disposed to be in contact with the lower end of the heating block 110 and formed so that the ejection port 151 is vertically penetrated.

The heating block 110 has an input channel 130 through which the filament passes through and is transported, and a heating wire for melting the filament may be disposed around the input channel 130. In addition, a material inlet 120 is coupled to the inlet of the input passage 130 and a material outlet 140 is formed at the outlet, so that the filament pressed by the filament supply unit 200 passes through the material inlet 120 It may be configured to melt and become a viscous liquefied state while passing through the input passage 130 and flow down through the material outlet 140. In this case, the material inlet 120, the input passage 130, and the material outlet 140 are formed in plural according to the number of collars of the filaments used.

A heat dissipation part 121 may be formed on the heating block 110 of the material introduction part 120 and above the coupling part of the heating block 110. The heat dissipation unit 121 may prevent heat radiated from the heating block 110 from being transferred to a member of a 3D printer such as the filament supply unit 200 by arranging a plurality of heat dissipation plates.

Filaments having different colors are melted and discharged from the plurality of material discharge ports 140, and the nozzle unit 150 may be formed in a shape and width capable of blocking all of the plurality of material discharge ports 140. In addition, an ejection opening 151 formed to penetrate the nozzle portion 150 vertically is disposed in the nozzle portion 150, and any one of the plurality of material outlets 140 is moved by moving the nozzle portion 150. When positioned so as to communicate with the ejection port 151, all material outlets 140 other than the communicated material outlets are blocked so that the molten filament does not flow down from the material outlets 140 other than the communicated material outlets 140. Can be configured.

In addition, the 3D printing color changing multi-nozzle system according to an example of the present invention with reference to FIG. 1 extends upward from the center of the nozzle unit 150 and is formed to penetrate the heating block 110 vertically ( 160) and a step motor 170 coupled to the upper end of the central axis 160, wherein the plurality of material outlets 140 are spaced at equal intervals from the center of the central axis 160 toward the outer side And the nozzle unit 150 may be rotated so that any one of the material discharge ports 140 communicates with the ejection port 151.

A cylindrical central axis 160 extending upwardly is formed at the center of the upper end of the nozzle unit 150, and the upper end of the central axis 160 may be coupled to the step motor 170.

The step motor 170 is a position control motor having a rotation of 1.8 degrees in one step, and can variously adjust the rotational force, rotational speed, and direction of the motor, and the frictional force between the heating block 110 and the nozzle unit 150 It is desirable to have sufficient rotational force to withstand it.

2 is a diagram illustrating a process of changing the color by changing the position of the ejection port 151 according to the present invention, and FIGS. (a) and (b) show differences in structures when each filament of a different color is output. will be. Hereinafter, referring to FIG. 2, a colored filament drawn from the right is referred to as a right filament, and a filament of another color drawn from the left is referred to as a left filament.

Figure (a) shows the configuration when the right filament is output.When the filament is advanced from the filament supply unit 200 of the right filament, additional filaments in addition to the molten filament continuously flow into the input flow path 130 of the right filament. And a process in which the molten filament is pushed toward the lower end of the input passage 130 and the material is injected into the right material outlet 140 is shown. At this time, the nozzle unit 150 is positioned so that the ejection port 151 communicates with the right material discharge port 140 and rotates so that the melted right filament can be injected through the ejection port 151.

Figure (b) shows a configuration when the right filament is changed to the left filament during injection. When the right filament is retracted by the height of the ejection port 151 from the right filament supply unit 200, the ejection port ( The molten right filament remaining in the 151 is also retracted from the ejection port 151. And, when the filament is advanced from the filament supply unit 200 of the left filament, the molten left filament is injected into the left material outlet 140, and the nozzle unit 150 has an ejection port 151 and the left material outlet 140 The left filament, which is rotated to communicate with each other and melted, is injected through the ejection port 151.

As in the above configuration, the filament of the color before the change is retracted, so that the molten filament does not remain in the ejection port 151, so it is possible to print continuously while changing the color without creating a prime tower, thereby reducing material cost. The output speed can be improved.

Since the filament supply unit 200 is stopped and no pressure is applied except for the colored filament to be output, the molten filament does not flow down, and even if the filament flows down, it may be blocked by the nozzle unit 150.

In addition, it is preferable that each surface of the heating block 110 and the nozzle unit 150 in contact with each other is surface-treated so that the frictional force is close to zero, and the molten filament is not counted out.

In the case of outputting in the configuration of FIG. 2, the position of the exit port 151 is changed by rotating the nozzle when the color is changed. When the changed color is continuously output from the position of the color before change, the position of the changed exit port 151 is The body part 100 may move along the XY axis on the plane, so that the position of the ejection port 151 may be moved to a position continuous with the color before the change.

6 is a flowchart illustrating a process of moving the X-Y axis on a plane when the color is changed to blue or red, and accordingly, the nozzle needs to be moved by the length A shown in FIG. 2.

3 to 5 are a thread 161 disposed on the central shaft 160 and formed along an outer circumferential surface of the central shaft 160, a bearing 164 disposed to contact the upper end of the heating block 110, and the It shows an example of the present invention further comprising a spring 163 disposed to contact the upper end of the bearing 164 and an adjustment nut 162 disposed to contact the upper end of the spring 163.

At this time, the central shaft 160 passes through the heating block 110, the bearing 164, the spring 163, and the adjustment nut 162 in order, and the adjustment nut is connected to the thread 161. It may be configured to fasten 162.

The nozzle unit 150 is disposed at the lower end of the heating block 110 so as to be in contact with the nozzle unit 150, and in order to prevent material from flowing through the gap between the heating block 110 and the nozzle unit 150, the nozzle unit ( It is preferable to combine 150) to contact by applying pressure in the direction of the heating block (110). Therefore, by fastening the adjustment nut 162 to the screw thread 161 formed along the outer circumferential surface of the central shaft 160 coupled to the nozzle unit 150, the heating block 110 and the nozzle unit 150 are strengthened. Can be combined. In addition, when the nozzle unit 150 and the heating block 110 are strongly coupled by fastening the adjustment nut 162 as described above, rotation of the nozzle unit 150 may be difficult. In the bearing 164, it may be disposed to further include a spring 163 on the upper end of the bearing 164.

The spring 163 is configured such that the central shaft 160 penetrates vertically, is disposed between the adjustment nut 162 and the heating block 110, and receives a force pressed by the coil spring 163 Spring 163 may be used.

When the lower end of the spring 163 is in contact with the upper end of the heating block 110, the bearing 164 rotates in response to the rotation of the central shaft 160, It is disposed between the heating block 110 and the spring 163 to prevent rotation in contact with the top surface.

At this time, when the bearing 164 and the spring 163 are further disposed and the adjustment nut 162 is fastened, the heating block 110 and the nozzle unit ( 150 is more strongly coupled, and the central shaft 160 and the nozzle unit 150 can be easily rotated even in a pressurized state by the bearing 164.

According to a preferred embodiment of the above configuration, by fastening the adjustment nut 162 to contact the upper end of the heating block 110, the heating block 110 and the nozzle unit 150 may be configured to be in contact with each other. . In addition, it may be configured by further disposing a bearing 164 and a spring 163 between the heating block 110 and the adjustment nut 162.

7 is another example of the nozzle unit 150, the nozzle unit 150 has an upper end of the ejection port 151 in communication with any one of the plurality of material discharge ports 140, and the lower end of the ejection port 151 May be configured to converge to the center of the nozzle unit 150. The ejection port 151 may be formed to communicate with the nozzle unit 150 vertically and to converge diagonally toward the center from the top to the bottom of the nozzle unit 150. In addition, the plurality of material outlets 140 formed at the lower end of the heating block 110 are radially spaced apart from the central axis 160 at regular intervals, and the upper end of the ejection port 151 is the plurality of materials. It is formed at a position in communication with the discharge port 140, and when the nozzle unit 150 rotates around the central axis 160, the upper end of the ejection port 151 is any one of the plurality of material discharge ports 140 It can be positioned to communicate with one.

Therefore, in the structure of the nozzle unit 150 of FIG. 7, since the outlet of the ejection port 151 is formed at the center of the nozzle unit 150, even if it is in communication with any one of the plurality of material discharge ports 140, the output is at the same position. It can be configured to be. In this case, it is possible to output while continuously changing the color without changing the position without moving the body part 100.

FIG. 8 is a bottom view of an example according to the present invention, wherein a plurality of ejection ports 151 are formed in the nozzle unit 150 to have different diameters, and the nozzle unit 150 is rotated to Any one of the ejection ports 151 may be configured to communicate with any one of the plurality of material discharge ports 140.

The ejection port 151 is formed to have a plurality of different diameters (eg, 0.2mm, 0.4mm, 0.6mm, etc.), and the plurality of ejection ports 151 are all one of the plurality of material discharge ports 140 It may be formed to be spaced apart at equal intervals from the center of the nozzle unit 150 so as to be interlocked with each other.

The configuration of the plurality of ejection orifices 151 of FIG. 8 can be applied to both the nozzle unit 150 having the configuration of FIGS. 1 to 7, and the diameter of the ejection orifice 151 can be quickly changed and output. It is possible to express more precise and various prints.

When changing from the structure of the nozzle unit 150 having the plurality of ejection ports 151 to an ejection port 151 having a different diameter during printing, the filament is retracted from the filament supply unit 200 and the inside of the output port 151 After retreating the molten filament of the nozzle unit 150 may be configured to change to an ejection port 151 having a different diameter by rotating.

9 shows the structure of an existing nozzle and will be described below in comparison with the structure of the present invention.

Figure (a) is a conventional method in which filaments of different colors are alternately injected and extruded through a nozzle whenever the output color is changed using one nozzle. In order to replace the green filament, you must remove all the red filament remaining inside the nozzle to print the green filament, so you need to print the remaining material on the nozzle to the prime tower to empty the nozzle and print the green filament. I had a hard time doing it. In the case of outputting in the method of the present invention, it is possible to output by changing the color without creating a prime tower.

Figure (b) is a conventional method of printing using a single nozzle, and in order to change the diameter of the nozzle during printing, it is necessary to replace the nozzle with a different diameter and print it, so there is a disadvantage in that it takes a replacement time. In the case of printing according to the method of the present invention, printing can be performed without replacing the nozzle, so that printing time can be shortened.

In the above, even if all the constituent elements constituting the embodiments of the present invention have been described as being combined into one or operating in combination, the present invention is not necessarily limited to these embodiments. That is, within the scope of the object of the present invention, all of the constituent elements may be configured or operated by selectively combining one or more. In addition, terms such as "include", "consist of" or "have" described above mean that the corresponding component may be present unless otherwise stated, excluding other components. It should not be construed as being able to include other components. All terms, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art, unless otherwise defined. Terms generally used, such as terms defined in the dictionary, should be interpreted as being consistent with the meaning of the context of the related technology, and are not interpreted as ideal or excessively formal meanings unless explicitly defined in the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain the technical idea, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

100: body 110: heating block
120: material entry part 121: heat dissipation part
130: input passage 140: material outlet
150: nozzle unit 151: ejection port
160: central axis 161: thread
162: adjustment nut 163: spring
164: bearing 170: step motor
200: filament supply unit 210: roller
300: Filament spool

Claims (6)

Body part; And
A plurality of filament supply units configured to input and output different colored filaments to the body portion; Including,
The body portion is a heating block configured to apply heat to the filament, a plurality of material lead-in portions coupled to the heating block and configured to lead the filament from the filament supply portion, and formed at the lower end of the heating block to communicate with a plurality of material lead-in portions, respectively. A plurality of material outlets, and a nozzle portion disposed to be in contact with the lower end of the heating block and formed so that the ejection port vertically penetrates,
A central axis extending upward from the center of the nozzle unit and vertically penetrating the heating block;
A step motor coupled to the upper end of the central axis;
A thread formed along the outer circumferential surface of the central axis;
A bearing disposed to be in contact with an upper end of the heating block;
A spring disposed to be in contact with the upper end of the bearing; And
Further includes; an adjustment nut disposed to be in contact with the upper end of the spring,
The central axis is configured to pass through the heating block, the bearing, the spring, and the adjustment nut in sequence and connect the adjustment nut to the screw thread,
The plurality of material outlets are spaced at equal intervals from the center of the central axis toward the outer side, and any one of the material outlets communicates with the ejection port by rotating the nozzle unit,
A 3D printing color change multi-nozzle system configured to block all material outlets other than the communicated material outlet when one of the plurality of material outlets is positioned to communicate with the ejection port by moving the nozzle unit.
delete In claim 1,
The body portion 3D printing color change multi-nozzle system, characterized in that configured to move along the XY axis on a plane.
In claim 1,
The nozzle unit 3D printing color change multi-nozzle system, characterized in that the upper end of the ejection port communicates with any one of the plurality of material outlets, and the lower end of the ejection port is configured to converge to the center of the nozzle unit.
In claim 1,
The nozzle part is formed in plural so that the ejection orifices have different diameters,
3D printing color changing multi-nozzle system, characterized in that configured to communicate with any one of the plurality of material outlets by rotating the nozzle unit. delete

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