Extruder for metal material and 3D printer using the same

An extruder for a metal material includes a cylinder having a receiving space in which a solid metal material is provided, a nozzle extending from a lower end of the cylinder, an upper coil provided on an outer surface of the cylinder and melting the solid metal material to form a liquid metal material, and a first lower coil provided on an outer surface of the nozzle to control an extruded shape of the liquid metal material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application claims priorities under 35 U.S.C. § 119 of Korean Patent Application Nos. 10-2016-0054242, filed on May 2, 2016, and 10-2016-0164670, filed on Dec. 5, 2016, the entire contents of which are hereby incorporated by reference.

BACKGROUND

The present disclosure relates to an extruder for a metal material and a three-dimensional (3D) printer using the same, and

more particularly, to an extruder for a metal material having an improved extrusion performance and a 3D printer using the same.

3D printing refers to processes in which a 3D printer receives information designed in 3D and outputs a 3D physical object by using the received information. The 3D printer is capable of relatively conveniently making a 3D physical object using a digital drawing. A 3D drawing is drawn through a program such as a 3D computer-aided design (CAD) capable of drawing a 3D drawing for 3D printing. A physical article may be mocked up from the beginning, or made by modifying a basic shape provided in a template. Several 3D printing service companies provide an online tool enabling even an ordinary person to easily draw a 3D drawing. The 3D drawing may also be created by merely using a 3D scanner or by a mechanical method of taking a picture without drawing a drawing. In industrial fields, the 3D printer is partially used in a manufacturing process.

SUMMARY

The present disclosure provides an extruder for a metal material using an induction heating method.

The present disclosure also provides an extruder for a metal material, capable of controlling an extrusion shape of the metal material.

The present disclosure also provides an extruder for a metal material capable of enhancing adhesion between metal materials extruded onto a support unit.

However, the inventive concept is not limited to the disclosure set forth herein.

An embodiment of the inventive concept provides an extruder for a metal material, the extruder including: a cylinder having a receiving space in which a solid metal material is provided; a nozzle extending from a lower end of the cylinder; an upper coil provided on an outer surface of the cylinder and configured to melt the solid metal material to form a liquid metal material; and a first lower coil provided on an outer surface of the nozzle and configured to control an extruded shape of the liquid metal material.

In an embodiment, the upper coil may produce a magnetic field inside the cylinder in order to induction heat the cylinder and the solid metal material.

In an embodiment, the upper coil may include a first coil provided adjacent to an upper portion of the cylinder, and a second coil provided adjacent to a lower portion of the cylinder, wherein the first coil may produce a first magnetic field inside the upper portion of the cylinder, and the second coil may produce a second magnetic field which is greater than the first magnetic field inside the lower portion of the cylinder.

In an embodiment, the upper coil may be wound in a helical shape around the cylinder.

In an embodiment, the upper coil may be more densely wound around the lower portion of the cylinder than around the upper portion of the cylinder.

In an embodiment, the cylinder and the nozzle may include a non-magnetic metal.

In an embodiment, the cylinder may include a non-magnetic metal, and the nozzle may include a non-metal.

In an embodiment, the first lower coil may produce an induction current on the surface of the liquid metal material inside the nozzle in order to control the extruded shape of the liquid metal material.

In an embodiment, the extruder for a metal material may further include a second lower coil disposed adjacent to a lower portion of the nozzle and configured to heat a metal material extruded from the nozzle onto a support part.

In an embodiment, the second lower coil may produce a magnetic field passing through the extruded metal material in order to induction heat the metal material.

In an embodiment, the first lower coil may be provided between the second lower coil and the nozzle.

In an embodiment, the second lower coil and the nozzle may be disposed at the same height from an upper surface of the support part.

In an embodiment, the second lower coil may be provided closer to the nozzle than to the upper surface of the support part.

In an embodiment, the extruder for a metal material may further include a temperature measurement unit configured to measure a temperature inside the cylinder.

In an embodiment, the extruder for a metal material may further include a control unit configured to adjust a temperature of the cylinder on the basis of data for the temperature inside the cylinder measured by the temperature measurement unit.

In an embodiment, the control unit may adjust the temperature of the cylinder by controlling a current flowing in the upper coil.

In an embodiment, the upper coil and the first lower coil may receive a current different from each other.

In an embodiment of the inventive concept, a 3D printer includes: a support unit; a metal material printing unit configured to extrude a metal material onto the support unit; and a non-metal material printing unit configured to extrude a non-metal material onto the support unit, wherein the metal material printing unit includes: a cylinder having a receiving space in which a solid metal material is provided; a nozzle extending from a lower end of the cylinder; an upper coil provided on an outer surface of the cylinder and configured to melt the solid metal material to form a liquid metal material; and a lower coil disposed on an outer surface of the nozzle and configured to control an extruded shape of the liquid metal material.

In an embodiment, the metal material printing unit may further include a metal material supply unit providing the solid metal material inside the cylinder, wherein the solid metal material may be a filament type or a powder type.

In an embodiment, the solid metal material may be a filament type, and the solid metal supply unit may include a cartridge.

DETAILED DESCRIPTION

For full understanding of configurations and advantages of the technical idea of the present invention, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

In the specification, it will be understood that when an element is referred to as being ‘on’ another element, it can be directly on the other element, or intervening elements may also be present. Like reference numerals refer to like elements throughout.

The embodiments in the detailed description will be described with sectional views and/or flowcharts as ideal exemplary views of the present invention. In the figures, the dimensions of layers and regions are exaggerated for clarity of illustration. Areas exemplified in the drawings have general properties, and are used to illustrate a specific shape of a semiconductor package region. Though terms like a first, a second, and a third are used to describe various regions and layers in various embodiments of the present invention, the regions and the layers are not limited to these terms. Thus, this should not be construed as limited to the scope of the present invention. These terms are used only to discriminate one region or layer from another region or layer. Embodiments described and exemplified herein also include a complementary embodiment thereof.

In the following description, the technical terms are used only for explaining specific embodiments while not limiting the present invention. The terms of a singular form may include plural forms unless referred to the contrary. The meaning of “include,” “comprise,” “including,” and/or “comprising,” specifies an element but does not exclude presence or addition of one or more other elements.

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

FIG. 1is a cross-sectional view of an extruder for a metal material according to exemplary embodiments of the inventive concept.

Referring toFIG. 1, an extruder may include a support unit100, an extrusion unit200melting and extruding a metal material (not illustrated) onto the support unit100, a coil unit300surrounding the extrusion unit200, a temperature measurement unit410, a metal material supply unit420, a pressure supply unit430and a control unit440.

Hereinafter, the metal material may include a metal having eutectic properties (or an eutectic metal) (for example, Ga—In-based metal, Ga—In—Sn-based metal, Ga—Sn-based metal and Pb—Sn-based metal), a mixture metal including an eutectic metal (for example, a mixture of an eutectic metal and particles of Cu, Ag, Au, Al and/or Pt having a size of several to several hundred nanometer (nm) or several to several hundred micrometer (μm)), an alloy containing Au (for example, an alloy of Au and at least one of Sn, Si, Ge, Sb, Ga, In or Bi), a metal mixture including the Au-containing alloy (a mixture of the Au-containing alloy and Cu, Ag, Au, Al and/or Pt particles having a size of several to several hundred nanometer (nm) or several to several hundred micrometer (μm)), or a refractory metal (for example, Al and AlSi).

The support unit100may provide a region to which a metal material is extruded. The support unit100may include a heat-resistant material. The support unit100may not be melted even when contacting the extruded metal material. In another exemplary embodiment, the support unit100may be moved by the control unit440. For example, the support unit100may be moved by the control unit440in a direction parallel with an upper surface of the support unit100so as to control an extrusion location of the metal material. In another embodiment, the location of the support unit100may be fixed. A susceptor (not illustrated) may be provided on the support unit100. The susceptor may cool down or heat a metal material extruded thereon.

The extrusion unit200may include a cylinder210providing a receiving space in which a metal material is received, and a nozzle220extending from a lower end of the cylinder210. In exemplary embodiments, the cylinder210and the nozzle220may have a cylindrical structure. The cylinder210and the nozzle220may have a cylindrical structure having a central axis along a first direction D1perpendicular to the upper surface of the support unit100. An inner surface of the cylinder210and an inner surface of the nozzle220may respectively have diameters W1and W2along a second direction D2parallel to the upper surface of the support unit100. The diameter W1of the inner surface of an upper portion of the cylinder210may be greater than the diameter W2of the inner surface of the nozzle220. An inner surface of a lower portion of the cylinder210may have a diameter W1, which decreases as it travels closer to the nozzle220. The cylinder210and the nozzle220may include a non-magnetic metal. For example, the cylinder210and the nozzle220may include stainless steel. In exemplary embodiments, the nozzle220may include a non-metal material. For example, the nozzle220may include a ceramic material. The extrusion unit200may be moved by the control unit440. For example, the extrusion unit200may be moved by the control unit440in a direction perpendicular to the upper surface of the support unit100or in a direction parallel to the upper surface of the support unit100, thereby capable of adjusting an extrusion location of the metal material.

The coil unit300may include a first coil310and a second coil320that are surrounding the cylinder210, and a third coil330and a fourth coil340that are surrounding the nozzle220. The first, second third and fourth coils310,320,330and340may include a conductive line. The first second third and fourth coils310,320,330and340may receive a current. In exemplary embodiments, the first second third and fourth coils310,320,330and340may respectively receive a different current from each other. In exemplary embodiments, the first second third and fourth coils310,320,330and340may receive the same current to each other. The intensity and direction of the current flowing in the first second third and fourth coils310,320,330and340may be controlled by the control unit440. The number of each of the first second third and fourth coils310,320,330and340illustrated herein is exemplified, and not limited to the illustration.

The first coil310may surround an upper portion of the cylinder210. In exemplary embodiments, the first coil310may extend in a helical shape along an upper outer surface of the cylinder210. That is, the first coil310may include a solenoid wound around the upper portion of the cylinder210. In exemplary embodiments, when a current flows in the first coil310, a first magnetic field (not illustrated) rotating centered on the first coil310may be produced. The first magnetic field may pass through the upper portion of the cylinder210to be provided inside the cylinder210.

The second coil320may surround a lower portion of the cylinder210. For example, the second coil320may extend in a helical shape along a lower outer surface of the cylinder210. The second coil320may include a solenoid wound around the lower portion of the cylinder210. The second coil320may be wound more densely than the first coil. For example, the distance between conductive lines next to each other of the second coil320in the first direction D1may be less than the distance between conductive lines next to each other of the first coil. The number of turns of the second coil320per the length of the lower portion of the cylinder210may be less than the number of turns of the first coil310per the length of the upper portion of the cylinder210. The lengths of the upper and lower portions of the cylinder210may be the lengths along a direction from the upper end of the cylinder210towards the lower end of the cylinder210. In exemplary embodiments, when a current flows in the second coil320, a second magnetic field (not illustrated) rotating centered on the second coil320may be produced. The second magnetic field may pass through the lower portion of the cylinder210to be provided inside the cylinder210. When an identical current flows in the first and second coils310and320, the intensity of the second magnetic field may be greater than the intensity of the first magnetic field. When the intensity of the currents flowing in the first and second coils310and320is changed, the intensity of the first and second magnetic fields may also be changed. When the currents flowing in the first and second coils310and320are changed by an equal intensity, the intensity changed in the second magnetic field may be greater than the intensity changed in the first magnetic field.

The third coil330may surround the nozzle220. For example, the third coil330may extend along an outer surface of the nozzle220. For example, the third coil330may have a circular shape circling around the nozzle220centered on the nozzle220. A conductive line of the third coil330may overlap the nozzle220in a direction parallel to the upper surface of the support unit100. In exemplary embodiments, the third coil330may be disposed at a position equal to or greater than the height of a lower surface of the nozzle220. When a current flows in the third coil330, a third magnetic field (not illustrated) rotating centered on the third coil330may be produced. The third magnetic field may pass through the nozzle220to be provided inside the nozzle220. In exemplary embodiments, the current flowing in the third coil330may include a pulse-type current.

The fourth coil340may be disposed adjacent to the lower portion of the nozzle220. The fourth coil340may have a shape radially travelling in a direction away from the nozzle220while circling around the nozzle220. The fourth coil340may be provided at a substantially equal height as the third coil330and the nozzle220. The fourth coil340and the nozzle220may be spaced from the support unit100by a substantially equal distance. For example, the nearest distance between the fourth coil340and the support unit100may by substantially equal to the nearest distance between the nozzle220and the support unit100. The fourth coil340may horizontally overlap the nozzle220and the third coil330. In exemplary embodiments, the fourth coil340may be provided at a less position than the positions of the nozzle220and the third coil330. The fourth coil340may be closer to the support unit100than the nozzle200. For example, the nearest distance between the fourth coil340and the support unit100may be less than the nearest distance between the nozzle220and the support unit100. When a current flows in the fourth coil340, a fourth magnetic field (not illustrated) rotating centered on the fourth coil340may be produced. The fourth magnetic field may pass through a metal material16on the support unit100.

The first magnetic field may melt a solid metal material (not illustrated) inside the upper portion of the cylinder210to form a liquid metal material (not illustrated). The liquid metal material may be moved in the lower portion of the cylinder210. The second magnetic field may maintain or raise a temperature of the liquid metal material inside the lower portion of the cylinder210. The liquid metal material may be moved in the nozzle220. The third magnetic field may control an extruded shape of the liquid metal material being extruded from the nozzle220. For example, the liquid metal material may be extruded in a droplet shape or continuously extruded. The fourth magnetic field may induction heat the metal material16on the support unit100.

The temperature measurement unit410may generate a temperature data for the temperature of the extrusion unit200and transmit the same to the control unit440. For example, the temperature measurement unit410may measure temperatures of the cylinder210and/or the metal material inside the cylinder210. The control unit440may control the temperature of the cylinder210on the basis of the temperature data received from the temperature measurement unit410.

The metal material supply unit420may supply a metal material (not illustrated) to the cylinder210. The metal material supply unit420may supply a powder type metal material or a filament type metal material inside the cylinder210. When the metal material is the powder type, the metal material supply unit420may include a cartridge receiving the powder type metal material therein. The powder type metal material may be supplied from the cartridge to the extrusion unit200in a required amount by the control unit440. When the metal material is the filament type, the metal material supply unit420may include a filament roll on which the filament type metal material is wound. The filament type metal material wound on the filament roll may be supplied from the filament roll to the extrusion unit200in a required amount by the control unit440.

The pressure supply unit430may provide pressure to the metal material so that the metal material is extruded from the inside of the extrusion unit200through the nozzle220. The strength of the pressure may be adjusted by the control unit440.

According to exemplary embodiments of the inventive concept, an extruder for a metal material having a coil unit300disposed adjacent to an extrusion unit200may be provided. An extruded shape of the metal material may be controlled by magnetic and electric fields produced inside the extrusion unit200.FIG. 2is a flowchart to describe a method of extruding a metal material according to exemplary embodiments of the inventive concept.FIGS. 3 to 8are cross-sectional views of an extruder for a metal material to describe a method of extruding a metal material according to exemplary embodiments of the inventive concept. For simplicity in description, description for content substantially identical to what is described with reference toFIG. 1may be omitted.

Referring toFIGS. 2 and 3, a solid metal material12may be provided inside the cylinder210. The solid metal material12may be a powder type or a filament type. In an embodiment, the solid metal material12may be supplied from the metal material supply unit420to the inside of the cylinder210.

A first current I1may be provided inside the first coil310. When viewed in a direction from the upper portion of the cylinder210towards the lower portion thereof (hereinafter referred to as “in a planar perspective”), the first current I1may flow in a clockwise direction. A first magnetic field32may be produced by the first current I1flowing in the first coil310, the first magnetic field32rotating in a right handed screw direction. The first magnetic field32may pass through the cylinder210and the solid metal material12inside the cylinder210. The cylinder210and the solid metal material12may be induction heated by the first magnetic field32. Induction heating may be heating by an induction current flowing in the cylinder210and the solid metal material12. The induction current flowing in the cylinder210and the solid metal material12may be generated when a direction and/or intensity of the magnetic field32passing through the cylinder210and the solid metal material12is changed. The induction heating may continue until the temperature of the solid metal material12arrives at a fusion point (or melting point) of the solid metal material12. A liquid metal material14may be formed by melting the solid metal material12by the induction heating (S100). The liquid metal material14may be moved in the lower portion of the cylinder210.

Referring toFIGS. 2 and 4, a second current12may be provided inside the second coil320. In a planar perspective, the second current12may flow in the clockwise direction. A second magnetic field34may be produced by the second current12flowing in the second coil320, the second magnetic field34rotating in a right handed screw direction. The second magnetic field34may pass through the cylinder210and the liquid metal material14inside the cylinder210. The second magnetic field34may produce an induction current on the surfaces of the cylinder210and the liquid metal material14. The cylinder210and the liquid metal material14may be induction heated by the induction current. A temperature of the liquid metal material14may be maintained greater than the fusion point (or melting point) of the solid metal material12by the induction heating (S200). Thereby, the liquid metal material14may be prevented from being hardened inside the cylinder210. The liquid metal material14may be moved in the nozzle220.

Referring toFIGS. 2, 5 and 6, the extruded shape of the liquid metal material14may be controlled by producing a third magnetic field36inside the nozzle220(S300). The third magnetic field36may be produced by a third current13flowing inside the third coil330. The third magnetic field36may have a traveling direction rotating in the right handed screw direction. When viewed in a plane, the third current13may flow in the clockwise direction. In exemplary embodiments, the third current13may flow in the counter-clockwise direction. The third magnetic field36may pass through the nozzle220and the liquid metal material14inside the nozzle220. The third magnetic field36may travel from the inside to the outside of the liquid metal material14to pass through a lower portion of the liquid metal material14. When the intensity and/or direction of the third magnetic field36are changed, an induction current (for example an eddy current) may be generated on a lower surface of the liquid metal material14. For example, when the intensity of the third magnetic field36is increased, the induction current flowing in a direction opposite to the direction of the third current13may be generated on the lower surface of the liquid metal material14. When the intensity of the third magnetic field36is decreased, the induction current flowing in the same direction as the direction of the third current13may be generated on the lower surface of the liquid metal material14. When the induction current flowing in the direction opposite to the direction of the third current13is formed on the lower surface of the liquid metal material14, a force F1directed toward the center of the lower surface of the liquid metal material14may be applied to the lower portion of the liquid metal material14by an interaction of the third magnetic field36and the induction current. The extruded shape of the liquid metal material14extruded from the nozzle220may be controlled by the force F1acting on the lower portion of the liquid metal material14. For example, as illustrated inFIG. 5, a width W3in the second direction D2of the liquid metal material14extruded from the nozzle220may be less than a separation distance W2along the second direction D2between the inner surfaces of the nozzle220. For example, as illustrated inFIG. 6, the liquid metal material14extruded from the nozzle220may be extruded in a droplet shape14a. The liquid metal material14may be extruded from the nozzle220onto the support unit100. For example, the liquid metal material14may be stacked on the metal material16on the support unit100.

Referring toFIG. 7, unlike what is illustrated inFIGS. 5 and 6, the third current13may not be provided inside the third coil330. In this case, the third magnetic field36passing through the liquid metal material14may not be produced in the inside of the nozzle220. Also, an induction current may not be produced on the lower surface of the liquid metal material14extruded from the nozzle220. Thus, the width W3of the liquid metal material14extruded from the nozzle220may be substantially equal to the separation distance between the inner surfaces of the nozzle220.

Referring toFIG. 8, a fourth current14may be provided to the fourth coil340. In a planar perspective, the fourth current14may flow in the clockwise direction. A fourth magnetic field38rotating in the right handed screw direction may be produced by the fourth current14flowing inside the fourth coil340. The fourth magnetic field38may pass through the metal material16on the support unit100. An induction current (for example the eddy current) may be produced on the surface of the metal material16on the support unit100by the fourth magnetic field38. The metal material16on the support unit100may be induction heated by the induction current (S400). When the metal material16on the support unit100is induction heated, a binding force between the metal material16on the support unit100and the liquid metal material14extruded on the metal material16may increase.

FIG. 9is a schematic diagram of a 3D printer according to exemplary embodiments of the inventive concept. For simplicity in description, description for content substantially identical to what is described with reference toFIG. 1will be omitted.

Referring toFIG. 9, the 3D printer includes a support unit100, a metal material printing unit1000, a non-metal material printing unit2000and a control unit440. The support unit100may be substantially same as the support unit100described with reference toFIG. 1. The metal material printing unit1000may include an extrusion unit200, a coil unit300, a temperature measurement unit410, a metal material supply unit420and a pressure supply unit430. The extrusion unit200, the coil unit300, the temperature measurement unit410, the metal material supply unit420and the pressure supply unit430may be substantially same as what are described with reference toFIG. 1, respectively.

The non-metal material printing unit2000may extrude a non-metal material (not illustrated) (for example, a thermoplastic resin material (ABS, PLA, PI, PMMA, PTFE, PEEK and urethane), glass and an amorphous-based material, a ceramic-based material, a magnetic body) onto the support unit100. The non-metal material printing unit2000may include a non-metal material extrusion unit2100. The non-metal material extrusion unit2100may include a cylinder2110providing a space in which the non-metal material is received, and a nozzle2120extending from a lower end of the cylinder2110. The non-metal material may be melted in the inside of the non-metal material extrusion unit2100to be extruded onto the support unit100through the nozzle2120. In exemplary embodiments, the non-metal material may be melted through the cylinder2110and the nozzle2120that are induction heated by a method substantially identical to what is described with reference toFIGS. 2 to 8. In this case, a coil (not illustrated) may be provided on an outer surface of the non-metal material extrusion unit2100. The coil may be substantially the same as the first and second coils310and320described with reference toFIG. 1. As described with reference toFIGS. 2 to 4, the cylinder2110and the nozzle2120may be induction heated by providing a current to the coil. However, above disclosure for the method of melting the non-metal material is exemplified, and the method is not limited to the disclosure. For example, in another embodiment, the non-metal material may be melted through a heating device (not illustrated) provided in the inside of the non-metal material extrusion unit2100.

The non-metal material printing unit2000may include a non-metal material supply unit2200. The non-metal material supply unit2200may provide a non-metal material in the inside of the non-metal material extrusion unit2100. In exemplary embodiments, the non-metal material may be a powder type or a filament type. When the non-metal material is the powder type, the non-metal material supply unit2200may include a cartridge having the powder type non-metal material received therein. The powder type non-metal material may be supplied in a required amount from the cartridge to the non-metal material extrusion unit2100by the control unit440. When the non-metal material is the filament type, the non-metal material supply unit2200may include a filament roll having the filament type non-metal material wound thereon. The filament type non-metal material wound on the filament roll may be supplied in a required amount from the filament roll to the non-metal material extrusion unit2200by the control unit440.

The non-metal material printing unit2000may include a temperature measurement unit (not illustrated) configured to measure a temperature inside the non-metal material extrusion unit2100, and a pressure supply unit (not illustrated) providing pressure to the non-metal material.

According to exemplary embodiments of the inventive concept, a 3D printer may include a metal material printing unit1000and a non-metal material printing unit2000. The metal material printing unit1000and the non-metal material printing unit2000may extrude a metal material50and a non-metal material60onto a support unit100. The metal material50and the non-metal material60may contact with each other. For example, the metal material50may be stacked on the non-metal material60, or vice versa. The metal material50may be provided onto the support unit100through induction heating.

FIG. 10is a graph to describe a characteristic of an extruding a metal material according to exemplary embodiments of the inventive concept.

Referring to theFIG. 10, the solid line represents the existence probability of the melted metal material according to the distance from the center of the nozzle when the current was not provided to the third coil. The dotted line represents when the current was provided to the third coil. When the existence probability of the melted metal material is 0.5 (that is, the value on the y-axis is 0.5), the droplet is produced.

The graph ofFIG. 10was drawn from Simulation Method using Finite Elements Method. Finite Elements Method is a method for calculating values by dividing a continuous structure into finite number of elements and applying an approximation scheme based on energy principle to each of the divided elements. A diameter of a nozzle was 50 micrometer (μm). A material of the nozzle was copper (Cu). The root-mean-square value of the current was 1000 A. The frequency of the current was 100 kHz. A metal material was Galinstan. Air pressure was provided to the metal material to extrude the metal material from the nozzle. When the current was not provided to the third coil, the radius of the droplet was about 15 micrometer (μm). When the current was provided to the third coil, the radius of the droplet was about 10 micrometer (μm). As a result, the radius of the droplet decreases when the current is provided to the third coil.

FIG. 11is a cross-sectional view of an extruder for a metal material according to exemplary embodiments of the inventive concept. For simplicity in description, description for content substantially identical to what is described with reference toFIG. 1may be omitted.

Referring toFIG. 11, the extruder for a metal material may include a support unit100, an extrusion unit200melting and extruding a metal material (not illustrated) onto the support unit100, a coil unit300surrounding the extrusion unit200, a temperature measurement unit410, a metal material supply unit420, a pressure supply unit430and a control unit440. Except for the extrusion unit200and the coil unit300, the extruder for the metal material ofFIG. 11may be substantially identical to the extruder for the metal material ofFIG. 1.

The extrusion unit200may be in plural. For example, two extrusion units200are illustrated. Each of the extrusion units200may be substantially identical to the extrusion unit200described inFIG. 1. The extrusion units200may be spaced apart from each other along the second direction D2. The extrusion units200may respectively extrude the metal materials differed from each other. According to the inventive concept, the various metal materials may be extruded at the same time to increase the speed of extrusion.

Unlike what is illustrated inFIG. 1, the coil unit300may surround a plurality of the extrusion units200. That is, the coil unit300may not be provided between the plurality of the extrusion units200.

FIG. 12is a cross-sectional view of an extruder for a metal material according to exemplary embodiments of the inventive concept. For simplicity in description, description for content substantially identical to what is described with reference toFIG. 11may be omitted.

Referring toFIG. 12, the extruder for a metal material may include a support unit100, an extrusion unit200melting and extruding a metal material (not illustrated) onto the support unit100, a coil unit300surrounding the extrusion unit200, a temperature measurement unit410, a metal material supply unit420, a pressure supply unit430and a control unit440. Except for a third coil330, the extruder for the metal material ofFIG. 12may be substantially identical to the extruder for the metal material ofFIG. 11. Unlike what is illustrated inFIG. 11, the coil unit300may comprise third coils330. The third coils330may surround a plurality of the extrusion units200, respectively. For example, the third coils330may surround a plurality of nozzles, respectively. That is, the third coils330may be provided between the plurality of the nozzles. Currents supplied to the third coils330may be different from each other. That is, the control unit440may individually control the currents supplied to the third coils330.

An extruder for a metal material according to exemplary embodiments of the inventive concept may include a coil unit provided on an outer surface of an extrusion unit receiving a metal material therein. When a current flows in the coil unit, the metal material inside the extrusion unit may be induction heated to be melted. When the melted metal material is extruded onto a support unit from the extrusion unit, the current is supplied to the coil unit so as to control an extruded shape of the metal material. When the metal material is extruded again on the metal material extruded onto the support unit, the current is supplied to the coil unit so as to heat the metal material extruded onto the support unit. However, an advantageous effect of the inventive concept is not limited the disclosure set forth herein.

As described above, the description of the embodiments according to the inventive concept provides illustrations for explanation of the technical idea of the inventive concept. Accordingly, the technical idea of the inventive concept is not limited to the embodiments set forth herein, and it is apparent that the technical idea of the inventive concept may be variously changed or modified by those of ordinary skilled in the art by combining the embodiments without departing from the scope of the technical idea of the inventive concept.