Magnesium alloy molded product and method for manufacturing same

Abstract

According to one embodiment of the present invention, provided are a magnesium alloy molded product and a method for manufacturing same, the method comprising: a first step of extruding a magnesium alloy billet into a pipe with a predetermined strength; a second step of heat-treating the magnesium alloy extruded in the first step; a third step of molding the heat-treated magnesium alloy at a predetermined temperature in a magnesium alloy molding device; a fourth step of coating the molded magnesium alloy molded product; and a fifth step of painting the coated magnesium alloy molded product.

Description

FIG. 6 is a schematic cross-sectional diagram of the magnesium alloy molding device according to an embodiment of the present disclosure. FIG. 7 is a perspective diagram of a magnesium alloy molded article manufactured by the manufacturing method of a magnesium alloy molded article according to an embodiment of the present disclosure. [Best Mode for Invention] Hereinafter, a magnesium alloy molded article and a manufacturing method thereof according to embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It is to be noted that in giving reference numerals to components of the accompanying drawings, the same components are represented by the same reference numerals even though the components are illustrated in different drawings. In addition, a detailed description of well-known features or functions will be ruled out in order not to unnecessarily obscure the gist of the present disclosure. Terms "first", "second", A, B, (a), (b), and the like, may be used in describing the components in the embodiments of the present disclosure. These terms are used only to distinguish any component and another component from each other, and the features, sequences, and the like of the corresponding components are not limited to these terms. In addition, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meanings as those generally understood by a person skilled in the art to which the present disclosure pertains. It should be interpreted that terms defined by a generally used dictionary have the same meanings as their meanings within the context of the related art, and these terms should not be ideally or excessively formally interpreted unless the context clearly dictates otherwise. FIG. 1 is a schematic flow diagram of a manufacturing method of a magnesium alloy molded article according to an embodiment of the present disclosure; FIG. 2 shows a crosssection of a magnesium alloy molded article before separate heat treatment after extrusion; FIG. 3 shows a cross-section of a magnesium alloy molded article after cold molding process; FIG. 4 shows a cross-section of a magnesium alloy molded article after hot molding process; FIG. 5 is a schematic configuration diagram of a magnesium alloy molding device according to an embodiment of the present disclosure; FIG. 6 is a schematic cross-sectional diagram of the magnesium alloy molding device according to an embodiment of the present disclosure; and FIG. 7 is a perspective diagram of a magnesium alloy molded article manufactured by the manufacturing method of a magnesium alloy molded article according to an embodiment of the present disclosure. Referring to FIGS. 1 to 6, the manufacturing method of a magnesium alloy molded article may include: extruding a magnesium alloy billet into a pipe having a predetermined strength (S100); heat-treating the extruded magnesium alloy (S200); molding, by the magnesium alloy molding device, the heat-treated magnesium alloy to a predetermined temperature (S300); coating the molded magnesium alloy molded article (S400); and painting the coated magnesium alloy molded article (S500) . Extruding The manufacturing method of a magnesium alloy molded article may include the extruding of the magnesium alloy billet (S100). The magnesium alloy billet may be extruded into the pipe shape having the predetermined strength, and the extruded magnesium alloy pipe may preferably have a strength of 350 megapascals (MPa). The extrusion is a process used to provide an object having a fixed cross-sectional contour, and the extrusion process may also increase a material strength. The extruded magnesium alloy article may be a pipe-shaped tube, and the magnesium alloy pipe may preferably have a length of 800 mm, and a diameter of 9.5 mm. If the extrusion is performed without preheating a die, a material-jamming phenomenon may easily occur, and even when the die is preheated before the extrusion, it may be preferable to adjust a ram speed or perform the extrusion without delay to prevent the die from being excessively cooled during the extrusion. If the die is difficult to be preheated or the ram speed is excessively low, a billet temperature may be continuously decreased to increase an extrusion load and cause the material-jamming phenomenon. As an extrusion ratio is increased, a microstructure may be more refined, which may be inversely proportional to elongation of the material even though securing its improved strength. If the extrusion ratio is excessively low, the material may have an excessively low strength, or the material may be manufactured unevenly due to a difference in the microstructure of the magnesium alloy extruded material in each portion, and many rough and large grains. The magnesium alloy may include an alloy such as an aluminum-zinc (AZ) based alloy having Al and Zn as its main additive elements, an aluminum-manganese (AM) based alloy having Al and Mn as its main additive elements, a zirconiumzinc (ZK) based alloy having Zr and Zn as its main additive elements, an aluminum-rare earth (AE) based alloy having Al and rare earths as its main additive elements, a yttrium-rare earth (WE) based alloy having Y and rare earths as its main additive elements, or an alloy having Li (lithium) as its main additive element, and is not limited thereto. For example, the magnesium alloy may include 4.8 to 6.2 wt% Zn, 0.45 to 0.1 wt% Zr, the remainder being magnesium and unavoidable impurities . Heat-treating The extruded magnesium alloy pipe may be heat-treated by the heat-treating (S200). In the extruding (S100), the extruded magnesium alloy pipe may be heat-treated, and the magnesium alloy pipe may have an increased tensile strength through the heat treatment. The increased tensile strength may preferably be approximately 10%. Molding The method may include the molding of the heat-treated magnesium alloy (S300) . In order to form the magnesium alloy pipe, the magnesium alloy may be molded only within a predetermined temperature range. The predetermined temperature may be preferably 150 to 300 degrees. A molding process suitable for the magnesium alloy molded article of the present disclosure may be achieved by a predetermined revolutions per minute (RPM), a predetermined feed speed, and a predetermined molding amount. The feed speed refers to a movement speed of a roller unit in an axial direction of a processing target, and the molding amount refers to a molding amount based on a diameter of the processing target. Preferably, the predetermined RPM may be 300 to 1200 RPM, the predetermined feed speed may be 2 to 14 mm / s, the predetermined molding amount may be 0.05 mm to 1.5 mm, and are not limited thereto. The molding process may be performed by a magnesium alloy molding device 100. The magnesium alloy molding device 100 may include: a fixing unit 110 supporting a processing target 10 to be rotatable; a rotating unit 120 opposite to the fixing unit and rotating the processing target 10 supported by the fixing unit; at least one heater module 140 detachably disposed on an outer circumferential surface of the processing target and heating the processing target 10; and at least one roller unit 130 applying a pressure to the processing target 10 while being moved in the axial direction of the processing target 10 and rotated along the outer circumferential surface of the processing target 10, wherein the roller unit 130 is rotated while having a predetermined incline relative to the processing target 10. The roller unit 130 may have a molding length of 600 mm. The processing target 10 may preferably be a magnesium pipe formed by extruding a magnesium billet. The processing target 10 may be supported by the support unit 110 and rotated by the rotating unit 120. The processing target 10 may have one surface coupled to the rotating unit 120, and the other surface supported by the support unit 110, and the processing target 10 coupled to the rotating unit 120 may be rotated by rotating the rotating unit 120. The support unit 110 may be configured to provide a pressure resisting a longitudinal expansion of the processing target 10 while a processing region of the processing target 10 is processed by the roller unit 130. The processing target 10 may undergo plastic deformation during the processing, thereby increasing its length, and the support unit 110 may here provide the pressure resisting the longitudinal expansion of the processing target 10. Each processing target 10 may have different physical properties such as different elongation and hardness, and thus have a different amount of elongation during the processing. Here, the support unit 110 may provide the pressure resisting the longitudinal expansion of the processing target 10 during the processing to thus allow the processing target 10 to maintain a constant length during the processing, ensuring its length remains the same after the molding. The roller unit 130 may mold the processing target 10 by applying the pressure thereto while being rotated along the outer circumferential surface of the processing target 10. The roller unit 130 may be moved in the axial direction of the processing target 10 while being rotated along the outer circumferential surface of the processing target 10, and apply the pressure to the processing target 10 while changing the molding amount that determines a cross-sectional area of the processing target 10 based on a user selection. The roller unit 130 may be moved in the axial direction of the processing target 10, thus forming various shapes of the magnesium alloy molded article, such as taper and wave. A diameter of the roller unit 130 may have a predetermined length, preferably 50 to 80 mm. The roller unit 130 may be inclined at a predetermined angle, and the processing target 10 may have the various shapes based on the incline. The incline angle may be determined based on a selection of a person skilled in the art. The rotating unit 120 may include a rotating drive shaft for rotating the rotating unit, and the rotating drive shaft may be rotated by a driving motor. For example, the driving motor may be a stepping motor, and is not limited thereto . The roller unit 130 is an element applying the pressure to the processing region of the processing target 10 for the processing, and may be fastened to, for example, a tool holder (not shown). The roller unit 130 may be rotatable in the magnesium alloy molding device 100, and thus be rotated by a frictional force when applying the pressure to the processing target 10 for processing the processing target. The magnesium alloy molding device 100 may be configured to be moved in the axial direction (horizontal direction in FIG. 5 and radial direction (vertical direction in FIG. 5) of the processing target 10 for the processing. The roller unit 130 may be a roller in direct contact with the processing target 10 for deforming the processing target 10. The plurality of roller units 130 may be provided and respectively be arranged at the upper and lower sides of the processing target 10 based on its height. A roller moving unit may be moved forward or backward toward the support unit 110 in a horizontal direction H. An adjustment link (not shown) may adjust a position of the roller unit 130 by being linked to the movement of the roller moving unit for the roller unit 130 to be moved toward or away from a central axis of the pressing target 10. The roller moving unit may be configured to move the roller unit forward or conversely to move the roller unit backward, in the horizontal direction of the processing target. To this end, the roller moving unit may be a cylinder or a servo motor disposed in the horizontal direction, and is not limited thereto . The roller unit 130 may further include a roller rotating unit (not shown) rotating the roller unit along the outer circumferential surface of the processing target 10. As the rotating unit 120 is rotated, the processing target 10 may be rotated around a longitudinal axis, and the roller unit 130 may press the outer surface of the processing target 10 being rotated, thus processing the processing region of the processing target 10 into a desired tapered shape . The fixing unit 110 or the rotating unit 120 may further include a compensation unit (not shown) compensating for shaking of the processing target 10 that occurs during the rotation or processing of the processing target 10. The compensation unit may preferably be a mandrel. The compensation unit may be inserted into the processing target 10 to compensate for the shaking that is caused by the rotation or processing of the processing target 10 to thus reduce a molding error caused by the shaking, thereby increasing molding reliability. The magnesium alloy molding device may further include the heater module 140 heating the processing target 10 to the predetermined temperature. At least one heater module 140 may be disposed along the outer circumferential surface of the processing target 10 while having the form of a detachable cover, and the heater module 140 mounted at a position requiring the heating among the plurality of heater modules 140 may be selectively driven based on a molding direction or a molding position. The magnesium alloy molding device may overcome a limitation in the molding direction by including the heater module 140. The magnesium alloy molding device may perform its forward, backward, or reciprocating movement based on a molding direction type. In addition, the magnesium alloy molding device may perform a reciprocating stroke, thus having the improved performance and productivity compared to its single stroke. The magnesium alloy molding device may heat the processing target to the predetermined temperature by including the heater module 140, and the predetermined temperature may be 100 °C to 500 °C, preferably 200 °C to 450 °C. Hereinafter, the heater module 140 may heat the processing target at 200 °C to 450 °C because the magnesium alloy has low ductility to thus lower its processability and moldability at a temperature less than 100 °C, and a property of the magnesium alloy itself may be changed at a certain higher temperature and a defect may easily occur therein. In addition, the magnesium alloy molding device may use a temperature controller and an actuator to improve its process-based operation, equipment usability, and small-quantity production of a variety of products. Coating and painting The magnesium alloy molded article molded in the molding (S300) may be coated in the coating (S400), and the coated magnesium alloy molded article may be painted in the painting (S500). The magnesium alloy molded article molded in the molding (S300) may be painted after being coated to thus form the magnesium alloy molded article. Experimental Example The magnesium alloy material is heat-treated to manufacture the magnesium alloy molded article. FIG. 2 shows a cross-section of the magnesium alloy molded article in Example 1 before being processed after extruding the magnesium alloy, FIG. 3 shows a cross-section of the magnesium alloy molded article in Example 2 after a cold molding process during the magnesium alloy molding process, and FIG. 4 shows a cross-section of the magnesium alloy molded article in Example 3 after a hot molding process during the magnesium alloy molding process. <Example 1> The magnesium alloy casting billet is extruded to thus manufacture the magnesium alloy extruded material. Next, the magnesium alloy extruded material is cut and processed to produce a specimen for a compression test, thereby manufacturing a specimen shown in FIG. 2. <Example 2> The magnesium alloy casting billet, which is the same as Example 1, is extruded to manufacture the magnesium alloy extruded material. The magnesium alloy extruded material is molded and processed by performing the cold molding process thereon, and the magnesium alloy molded article is then cut and processed to produce the specimen for the compression test, thereby manufacturing a specimen shown in FIG. 3. <Example 3> The magnesium alloy casting billet, which is the same as Example 1, is extruded to manufacture the magnesium alloy extruded material. Next, the magnesium alloy extruded material is molded and processed. Here, the molding process is performed under a temperature condition of 150 to 300 degrees during the molding process, and the magnesium alloy molded article is then cut and processed to produce the specimen for the compression test, thereby manufacturing a specimen shown in FIG. 4. The present disclosure is not necessarily limited to the embodiments described above, and it is apparent to a person skilled in the art to which the present disclosure pertains that the present disclosure may be variously modified and implemented within the range equivalent to the 5 present disclosure. Therefore, the true scope of the present disclosure is defined by the claims set forth below.

Claims

[CLAIMS]

1. A manufacturing method of a magnesium alloy molded article, the method comprising:extruding a magnesium alloy billet into a pipe having a predetermined strength;heat-treating the extruded magnesium alloy in the extruding;molding, by a magnesium alloy molding device, the heat-treated magnesium alloy to a predetermined temperature;coating the molded magnesium alloy molded article; and painting the coated magnesium alloy molded article.

2. The method of claim 1, wherein the predetermined strength is 350 megapascals (MPa).

3. The method of claim 1, wherein the predetermined temperature is between 150°C and 300°C.

4. The method of claim 1, wherein the magnesium alloy molding device includes:a fixing unit supporting a processing target to berotatable;at least one heater module detachably disposed on an outer circumferential surface of the processing target and heating the processing target;a rotating unit opposite to the fixing unit and rotating the processing target supported by the fixing unit; andat least one roller unit applying a pressure to the processing target while being moved in an axial direction of the processing target and rotated along the outer circumferential surface of the processing target.

5. The method of claim 4, wherein the rotating unit is rotated at 300 to 1200 revolutions per minute (RPM).

6. The method of claim 4, wherein a movement speed of therollerunit is 2 to14 mm / sin theaxial direction of theprocessing target.

7. The method of claim 4, wherein a molding amount of theroller unit is 0.05 to 1.5 mm.

8. The method of claim 4, wherein the roller unit is rotated while having a predetermined incline toward the processing target.5

9. A magnesium alloy molded article manufactured by molding a magnesium alloy material, which is heated to 200°C to 450°C by a magnesium alloy molding device, with a molding 10 amount of 0.05 to 1.5 mm.

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