Method for manufacturing metal molded products

Abstract

To provide a technique for suppressing the deformation of a mold caused by a press.SOLUTION: Provided is a method for producing a metal molded article which is molded by press-molding a semi-solidified metal material with a first mold and a second mold. The production method has a step of arranging the semi-solidified metal material at the first mold or the second mold located below. Further, the production method has a step of bringing the first mold and the second mold closer to each other till the first mold or the second mold located above is displaced to a bottom dead point to press the semi-solidified metal material. Further, the production method has a step of, after the first mold or the second mold displaced to the bottom dead point reaches the bottom dead point, displacing the first mold and the second mold to a holding point far from the lower dead point to hold the first mold and the second mold.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to press forming of semi-solid metallic materials. [Background technology]

[0002] A method for producing a molded product by placing a semi-solid metal material in a mold and press-forming it is known. Patent Document 1 discloses a press-forming method in which a mold having an upper die, an upper die slider, and a lower die is used to press a semi-solid aluminum alloy metal placed in the mold to form a product. In this press-forming method, the upper die and upper die slider are lowered to continuously apply pressure to the aluminum alloy until the temperature of the aluminum alloy reaches the end-of-solidification temperature, thereby forming a primary molded product. Thereafter, only the upper die slider is lowered to further apply pressure to the primary molded product, thereby forging the aluminum alloy and forming a product with excellent mechanical properties. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-118030 Summary of the Invention [Problem to be solved by the invention]

[0004] In press molding of semi-solid metal materials, it is preferable to use a large pressing pressure in order to ensure that the material reaches the edges of the molded product during the pressing process, to allow the material to blend in to prevent surface peeling of the molded product, and to remove air bubbles that have formed inside the material.

[0005] However, in the case of press molding in which a semi-solid metal material placed in a lower mold having a bottom surface and a side wall extending from the bottom surface flows between the side walls of the upper and lower molds when pressed by the upper mold, the pressure applied to the semi-solid metal material from the upper mold is transmitted to the side wall of the lower mold. Therefore, when the press pressure increases, a large pressure is applied to the side wall of the lower mold, which is likely to cause deformation of the lower mold and affect the molding accuracy of the molded product.

[0006] An object of one aspect of the present disclosure is to provide a technique for suppressing deformation of a mold due to pressing. [Means for solving the problem]

[0007] One aspect of the present disclosure is a method for manufacturing a metal molded product formed by press-forming a semi-solid metal material using a first mold and a second mold arranged to face each other in the vertical direction. The first mold has a protrusion capable of pressing the semi-solid metal material. The second mold has a base and a sidewall extending from the base in the direction in which the first mold is arranged. When combined with the first mold, the second mold covers the protrusion so that the base and the sidewall are positioned with a gap between them. The method for manufacturing a metal molded product includes placing a semi-solid metal material in the first mold or the second mold located below. The method for manufacturing a metal molded product also includes pressing the semi-solid metal material by bringing the first mold or the second mold located above close to each other until the first mold or the second mold located above is displaced to the bottom dead center. The method for manufacturing a metal molded product also includes displacing the first mold or the second mold to a holding point away from the bottom dead center after the first mold or the second mold has displaced to the bottom dead center and holding the first mold or the second mold.

[0008] In this configuration, the positions of the first and second dies are maintained with the upper first or second die at a holding point, which is a position displaced from bottom dead center. Therefore, compared to when the upper first or second die is maintained at bottom dead center, the pressure applied to the semi-solidified metal material during pressing is reduced, and the pressure transmitted to the side wall of the second die via the semi-solidified metal material is reduced. Therefore, deformation of the dies due to pressing can be suppressed.

[0009] In one embodiment of the present disclosure, at least one of the first mold and the second mold may be displaced by control using a servo motor. With this configuration, the timing and degree of displacement of the upper first mold or the second mold from the bottom dead center to the holding point can be controlled with precision. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a diagram schematically illustrating a cross-sectional structure of a press-forming device. [Figure 2] 2A to 2D are diagrams illustrating a method for producing a molded product according to an embodiment using a press molding device. [Figure 3] FIG. 2 is a diagram schematically showing the positions of the bottom dead center and the holding point in the first mold. [Figure 4] 4A to 4D are diagrams schematically showing, in top view, the shape of the second mold in each step of the method for producing the molded product shown in FIGS. 2A to 2D. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. Configuration of press forming equipment] The press-forming apparatus 100 shown in FIG. 1 is an apparatus for producing a metal molded product by press-forming a semi-solid metal material using a first mold 1 and a second mold 2 (described later). The metal molded product is, for example, a pot. In the following description, a semi-solid aluminum material is used as an example of the semi-solid metal material. Note that the metal type of the semi-solid metal material is not limited to aluminum, and various other metals can be used. Furthermore, the directions of up / down, left / right, and front / back in the following description are used for convenience of explanation and do not limit the manner in which the press-forming apparatus 100 can be used.

[0012] The press-molding apparatus 100 includes a first mold 1 , a second mold 2 , a slide 3 , and a bolster 4 . The first die 1 and the second die 2 are arranged so as to face each other in the vertical direction. In this embodiment, the first die 1 is located at the top, and the second die 2 is located at the bottom. Specifically, the first die 1 is fixed to the bottom surface of a slide 3 that moves in the vertical direction by a motor or the like, and the second die 2 is fixed to the top surface of a bolster 4 that is arranged below the slide 3. In this embodiment, press working is performed by the first die 1 and the second die 2 by moving the first die 1 in the vertical direction under the control of a servo motor 200 shown in FIG. 1 .

[0013] The first mold 1 has a main body 11 and a protruding portion 12. The protruding portion 12 is a cylindrical portion that protrudes downward from the main body 11 and is capable of pressing the semi-solid metal material. Note that the shape of the protruding portion is not limited to a cylindrical shape, and can take various shapes corresponding to the shape of the metal molded product. The second mold 2 is box-shaped and open at the top, and has a cylindrical internal space with a diameter larger than that of the protrusion 12 of the first mold 1. The shape of the internal space of the second mold is not limited to a cylindrical shape, and can take various shapes corresponding to the shape of the metal molded product. The second mold 2 has a base 21 and a side wall 22. The base 21 faces the tip of the protrusion 12. The side wall 22 extends from the edge of the base 21 in the direction in which the first mold 1 is disposed, i.e., upward. The side wall 22 is provided so as to surround the edge of the base 21.

[0014] The internal space of the second mold 2 is a space surrounded by a base 21 and a side wall 22, and the protruding portion 12 of the first mold 1 can be inserted into this internal space. When the second mold 2 is combined with the first mold 1, the second mold 2 covers the protruding portion 12 of the first mold 1 so that the entire inner circumferential surfaces of the base 21 and the side wall 22 are positioned with a gap between them. When the first mold 1 and the second mold 2 are combined, the gap formed between the base 21 and the side wall 22 and the protruding portion 12 is a space for forming the semi-solid aluminum material (hereinafter referred to as a forming space 5).

[0015] [2.Metal molding method using press molding equipment] Next, a method for producing a metal molded product (hereinafter referred to as molded product 60) by press-forming a semi-solid aluminum material (hereinafter referred to as material 6) using the above-described press-forming apparatus 100 will be described with reference to Figures 2A to 2D. The method for producing molded product 60 of this embodiment includes a placement step, a pressing step, a holding step, and a release step. Changes in the shape of second mold 2 as viewed from above during each step shown in Figures 2A to 2D are shown with reference to Figures 4A to 4D.

[0016] <Placement process> First, as shown in Fig. 2A, material 6 is placed in the internal space of second mold 2. As shown in Fig. 4A, in the initial state of second mold 2 in the placing step, second mold 2 is not deformed.

[0017] <Pressing process> 2B, the first mold 1 and the second mold 2 are moved closer to each other until the first mold 1 is displaced to the bottom dead center P1, thereby pressing the material 6. Specifically, the first mold 1 is lowered to the bottom dead center P1 by control using the servo motor 200 shown in FIG. 1, and the material 6 is pressed by the protrusion 12. The material 6 is compressed and deformed by being pressed, and is filled into the molding space 5.

[0018] When the first mold 1 is at bottom dead center P1, a large pressure (e.g., several hundred tons) is applied to the material 6. The large pressure applied to the material 6 when the first mold 1 is at bottom dead center P1 varies depending on the size and rigidity of the first mold 1 and the second mold 2. This makes it easier for the material 6 to reach the edges of the molding space 5, reduces the occurrence of interfaces when the material 6 solidifies, and makes it easier to remove air bubbles that have formed inside the material 6. Meanwhile, the large pressure applied to the material 6 from the first mold 1 is transmitted to the side wall 22 of the second mold 2 via the material 6. This applies a large pressure to the side wall 22 of the second mold 2, causing deformation of the second mold 2. Specifically, as shown in FIG. 4B , the second mold 2 expands, and the left and right side walls of the side wall 22 of the second mold 2, which are thinner than the front and rear side walls, bend outward.

[0019] <Holding process> Next, as shown in FIGS. 2C and 3 , the first mold 1 and the second mold 2 are slightly separated from each other to displace the first mold 1 to the holding point P2 immediately after it reaches bottom dead center P1, and then the first mold 1 and the second mold 2 are held at the separated position. Specifically, by control using a servo motor 200, the first mold 1 is slightly raised to the holding point P2 immediately after it reaches bottom dead center P1, and then the first mold 1 is held at the holding point P2. "Immediately after reaching bottom dead center P1" is preferably, for example, less than 0.5 seconds after it reaches bottom dead center P1. Note that the timing at which the first mold 1 is displaced depends on the cooling rate of the material 6. In other words, since the cooling rate of the material 6 varies depending on the materials of the first mold 1 and the second mold 2, the timing at which the first mold 1 is displaced also depends on the materials of the first mold 1 and the second mold 2. Furthermore, the distance from bottom dead center P1 to the holding point P2 is preferably, for example, less than 1 mm. The distance from the bottom dead center P1 to the holding point P2 varies depending on the size and rigidity of the first mold 1 and the second mold 2, etc.

[0020] As described above, when the first mold 1 is displaced from bottom dead center P1 to the holding point P2, i.e., when the first mold 1 is slightly raised by less than 1 mm, the pressure applied by the first mold 1 to the material 6 is reduced to, for example, about half of the pressure applied when the first mold 1 was at bottom dead center P1. This eliminates or reduces the deformation of the second mold 2 shown in FIG. 4B that occurred during the pressing process described above, and as shown in FIG. 4C, the shape of the second mold 2 returns to a state with almost no deformation, similar to the initial state shown in FIG. 4A. Then, with the second mold 2 in a state with almost no deformation, the relative distance between the first mold 1 and the second mold 2 is maintained, and the compressed and deformed material 6 is cooled.

[0021] <Removal process> Next, as shown in FIG. 2D, the first mold 1 and the second mold 2 are separated until the first mold 1 returns to its initial position before pressing, and the molded product 60 is released from the second mold 2. Specifically, the first mold 1 is moved upward by control using the servo motor 200, and the molded product 60 is released from the second mold 2. Thereafter, the molded product 60 is removed from the first mold 1, thereby completing the production of the molded product 60. As described above, the compressed and deformed material 6 is cooled in the state in which the second mold 2 is almost undeformed as shown in FIG. 4C, and therefore a molded product 60 with a highly accurate shape can be obtained.

[0022] [3.Effects] According to the embodiment described above in detail, the following effects can be obtained. (3a) In this embodiment, after pressing the material 6, the first mold 1 is held at a holding point P2, which is a position slightly elevated from the bottom dead center P1. Therefore, compared to a manufacturing method for a metal molded product in which the first mold 1 is held at the bottom dead center P1, the pressure applied to the material 6 during pressing and transmitted to the side wall portion 22 of the second mold 2 via the material 6 is reduced. In other words, by including the holding step, deformation of the second mold 2 that occurs during the pressing step is eliminated or reduced. Therefore, deformation of the second mold 2 due to pressing can be suppressed.

[0023] As a result, even if a large pressure is applied to the material 6 in the pressing process, the compressed and deformed material 6 is cooled while the second mold 2 is in a state where it is hardly deformed, thereby improving the molding accuracy of the molded product 60 formed from the material 6, which is easily affected by the shape of the mold. Note that in a manufacturing method for a metal molded product that does not include a holding step, the compressed and deformed material 6 is cooled while the second mold remains in a state where it is deformed due to the application of a large pressure to the material 6 in the pressing process. Therefore, a molded product 61 with a distorted shape is likely to be formed.

[0024] (3b) In this embodiment, a large pressure is applied to the material 6 in the pressing process, which makes it easy for the material 6 to reach the edges of the molding space 5. This makes it possible to prevent the molded product 60 from being defective with its edges chipped, and also makes it easy to remove excess material 6, which is placed in an amount greater than the required weight, from the clearance between the first mold 1 and the second mold 2 as flash.

[0025] Furthermore, since a large pressure is applied to the material 6 in the pressing process, an interface that occurs when the material 6 solidifies is unlikely to occur in the molded product 60. As a result, material peeling due to the interface is suppressed, and the surface condition of the molded product 60 can be improved.

[0026] Furthermore, since a large pressure is applied to the material 6 in the pressing process, air bubbles generated inside the material 6 are easily removed. Therefore, the inclusion of air bubbles in the molded product 60 can be suppressed.

[0027] (3c) In this embodiment, the first mold 1 moves under control using the servo motor 200. Therefore, the timing and degree of slight rise of the first mold 1 from the bottom dead center P1 to the holding point P2 can be precisely controlled.

[0028] 4. Other Embodiments Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take on various forms.

[0029] (4a) In the above embodiment, a configuration in which the first mold 1 moves in the vertical direction is exemplified, but the mold that moves is not limited to the first mold 1. For example, the second mold 2 may move in the vertical direction, or both the first mold 1 and the second mold 2 may move in the vertical direction.

[0030] (4b) In the above embodiment, the press molding apparatus 100 is configured such that the first mold 1 is located above and the second mold 2 is located below, but the configuration of the press molding apparatus is not limited to this. For example, the press molding apparatus may be configured such that the second mold 2 is located above and the first mold 1 is located below.

[0031] In this configuration, the material 6 is placed on the protrusion 12 of the first mold 1 located below. Then, by controlling the servo motor 200, at least one of the first mold 1 and the second mold 2 is displaced to perform press working. For example, the first mold 1 located below may move vertically, the second mold 2 located above may move vertically, or both the first mold 1 and the second mold 2 may move vertically.

[0032] (4c) In the above embodiment, the first mold 1 is moved up and down under the control of the servo motor 200, but the method of moving at least one of the first mold 1 and the second mold 2 is not limited to this. For example, the movement of at least one of the first mold 1 and the second mold 2 may be controlled by hydraulic pressure or a crank press.

[0033] (4d) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Also, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. [Explanation of symbols]

[0034] 1...first mold, 2...second mold, 3...slide, 4...bolster, 5...molding space, 6...material, 11...main body, 12...protrusion, 21...base, 22...side wall, 60...molded product, 100...press molding device, 200...servo motor, P1...bottom dead center, P2...holding point.

Claims

1. A method for manufacturing a metal molded product formed by press-forming a semi-solid metal material using a first mold and a second mold that are arranged to face each other in a vertical direction, comprising: the first die has a protrusion capable of pressing the semi-solid metal material; the second mold has a base and a sidewall extending from the base in a direction in which the first mold is disposed, and covers the protruding portion so that the base and the sidewall are positioned with a gap between them when combined with the first mold; The method for producing the metal molded product comprises: Placing the semi-solid metal material in the first mold or the second mold located below; pressing the semi-solid metal material by moving the first die and the second die closer to each other until the first die or the second die positioned above is displaced to the bottom dead center; After the first mold or the second mold has been displaced to the bottom dead center and reaches the bottom dead center, the first mold and the second mold are displaced to a holding point away from the bottom dead center to hold the first mold and the second mold; Equipped with A method for manufacturing a metal molded product, wherein the pressure applied to the semi-solidified metal material from the first mold at the holding point is smaller than the pressure applied to the semi-solidified metal material from the first mold at the bottom dead center.

2. The method for producing a metal molded product according to claim 1, A method for manufacturing a metal molded product, wherein at least one of the first mold and the second mold is displaced by control using a servo motor.

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