JP2017047452A - Manufacturing method of foamed metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of making a process for filling gas which gets to nucleus of foaming in molten metal from an external part unnecessary, and manufacturing foamed metal which causes air bubbles to be uniformly dispersed and has high quality, in the manufacturing method of foamed metal using a forming mold.SOLUTION: A manufacturing method of foamed metal as the method of manufacturing foamed metal having air bubbles in metal matrix by using molds 1, 2 at least includes: a process of filling molten metal 20 containing dissolved gas into a cavity of a closed mold; a process of closing the interior of the cavity after filling the molten metal 20; a process of reducing a pressure in the cavity and turning the dissolved gas into air bubbles by opening the first mold while maintaining closure in the cavity; a process of cooling the metal matrix in which air bubble-forming is advanced; and a process of removing the foamed metal from the mold by opening the second mold after cooling the metal matrix.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for producing a foam metal.

  A foam metal having a large number of bubbles inside a metal or alloy is known. Some are closed-celled and others are open-celled. Foamed metal is used in many fields because it has the required strength and is lightweight. The production of the foam metal is mainly performed by preparing a mixture of a metal base material and a foaming agent, and including gas generated by the decomposition of the foaming agent as bubbles in the base material. Since a foaming agent is generally expensive and its production cost is high, a method for producing a foam metal without using a foaming agent has been proposed, and an example thereof is described in Patent Document 1.

  The method described in Patent Document 1 includes a step of introducing a molten metal base material into a cavity of a mold and mixing gas into the base material, and then opening the mold to open a space inside the mold. The process includes a step of generating bubbles by the gas in the base material and a step of cooling the base material in which the bubbles are formed.

JP 2013-007097 A

  The method for producing a foam metal described in Patent Document 1 has an advantage that a foam metal can be produced at a low cost because a dedicated foaming agent is not used. However, the gas that becomes the core of foaming is mixed into the metal base material (metal melt) introduced into the cavity. In this process, it is difficult to uniformly disperse the mixed gas in the metal base material. As a result, there is a high possibility that the foamed metal has a non-uniform distribution of bubbles. Moreover, the process of mixing the gas used as the core of foaming into a molten metal is also needed.

  The present invention has been made in view of the above circumstances, and in a method for producing a foam metal having bubbles in a metal base material using a mold, a foaming agent is formed without using a foaming agent. It is an object of the present invention to provide a more improved method for producing a foam metal, in which the distribution can be made more uniform, whereby a highly homogeneous foam metal can be obtained at low cost.

  The method for producing a foam metal according to the present invention is a method for producing a foam metal having bubbles in a metal base material using a mold, and injecting a molten metal containing dissolved gas into a closed mold cavity. A step of sealing the inside of the cavity after the injection of the molten metal, and a step of opening the first mold while maintaining the sealing of the cavity to depressurize the inside of the cavity to make the dissolved gas into a bubble And a step of cooling the metal base material that has been bubbled, and a step of opening the second mold after the metal base material is cooled and releasing the foam metal from the mold. And

  In the method for producing a foam metal according to the present invention, the dissolved gas normally contained in the molten metal is actively used for the formation of bubbles. The first mold opening is performed while keeping the sealed state of the cavity containing the molten metal and in the sealed state. As a result, the volume of the cavity is increased, and the pressure inside the cavity is reduced. Due to the reduced pressure, the dissolved gas in the molten metal is bubbled. The dissolved gas exists almost uniformly in the molten metal, and the formed bubbles are also uniformly dispersed in the cavity. By cooling the inside of the cavity in this state, a foam metal in which bubbles are almost uniformly dispersed is formed in the cavity. After cooling, a second mold opening is performed to take out the foam metal formed from the mold.

  According to this manufacturing method, the step of injecting a gas that becomes the core of foaming into the molten metal from the outside is unnecessary, the number of steps is reduced, and the manufacturing cost is reduced. Furthermore, a high-quality foam metal in which air bubbles are uniformly dispersed can be produced.

The 1st figure which shows the manufacturing process of the manufacturing method of the metal foam by this invention. The 2nd figure which shows the manufacturing process of the manufacturing method of the metal foam by this invention. The 3rd figure which shows the manufacturing process of the manufacturing method of the metal foam by this invention. The figure which shows the manufactured foam metal.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a first view showing a manufacturing process of a method for manufacturing a foam metal according to the present invention. The apparatus for carrying out the method may basically be an apparatus used for ordinary die casting and the like, and the apparatus 30 includes two molds 1 and 2, and a mold opening and a mold. A mold moving mechanism (not shown) for moving one or both of the molds at the time of fastening or the like is provided. In the illustrated apparatus 30, the mold 1 is a movable mold and the mold 2 is a fixed mold. The mold 1 has a recess 3, and the mold 2 has a convex portion 4 that enters the recess 3. FIG. 1 shows a state in which the mold is closed, that is, both molds 1 and 2 have their parting surfaces brought into contact with each other. A cavity 5 serving as a molding space is formed between the convex portions 4.

  The mold 2 is provided with a sleeve 6 communicating with the cavity 5 to be formed, and a molten metal, that is, a molten metal 20 is supplied into the sleeve 6 from the opening 7. The sleeve 6 is provided with a plunger 8, and the molten metal 20 supplied into the sleeve 6 is pumped into the cavity 5 by the movement of the plunger 8.

  The above configuration may be the same as a conventionally known casting apparatus. The foamed metal manufacturing apparatus 30 according to the present invention further includes a sealing means 9 capable of maintaining the inside of the cavity 5 in a sealed state cut off from outside air while the cavity 5 is filled with the molten metal 20. . Although there is no restriction | limiting in the sealing means 9, in the thing of illustration, it is comprised by the member 10 which can cover the outer periphery of the parting surface of the metal mold | die 1 and 2 airtightly. And the member 10 is made to move with the metal mold | die 1 maintaining the airtightness in the cavity 5, when the metal mold | die 1 moves to the opening direction.

  In producing the foam metal, as shown in the drawing, the molten metal 20 containing dissolved gas is supplied from the opening 7 into the sleeve 6 with the mold closed. FIG. 1 shows this state. Next, the plunger 8 is moved leftward in the drawing, and the molten metal 20 in the sleeve 6 is fed into the cavity 5. FIG. 2 shows this state. In order to facilitate filling of the molten metal 20 into the cavity 5, the air in the cavity 5 may be exhausted to the outside along with the filling of the molten metal 20. However, after the molten metal 20 is filled, the communication between the exhaust port and the outside air can be blocked by an appropriate means.

  When the filling of the molten metal 20 into the cavity 5 is completed, preferably, immediately after the filling is completed, the first mold opening for slightly moving the mold 1 leftward in the drawing is performed. The state is shown in FIG. The volume of the cavity 5 expands by the first mold opening. There is no limit to the distance traveled, but it is usually a few millimeters. As described above, even if the first mold opening is performed, the communication between the inside of the cavity 5 and the outside air is blocked, and the outside air does not enter the cavity 5. Therefore, the pressure in the cavity 5 is reduced in proportion to the volume expansion amount. When the pressure in the cavity 5 is lowered, the dissolved gas in the molten metal 20 is bubbled, and many bubbles 21 are formed in the molten metal 20.

  In this state, the mold is cooled by a conventional method, and after cooling, the second mold is opened to remove the molded product from the mold. FIG. 4 shows a cross-sectional view of the cast product (cast product made of foam metal) 40 after demolding. As shown in the drawing, a casting 40 in which the bubbles 21 are dispersed almost uniformly is obtained.

  In the method for producing a foam metal according to the present invention, the extent of the opening distance in the first mold opening described above depends on the volume of the cavity in the mold to be used, the amount of dissolved residue of the molten metal to be used, and It is set by calculation or experimentally while taking into consideration the proportion of bubbles in the metal foam to be obtained. Moreover, aluminum, magnesium, zinc, brass, its alloy, etc. can be used as a metal base material which is a molten metal.

In the experiments by the present inventors, aluminum having a dissolved gas amount of 5 cc / 100 g Al was used as a metal base material, and molten aluminum was filled into the cavity 5 having a volume of 670 cm ³ , and the volume increase rate of the cavity 5 was 0 immediately after filling. When the first mold opening was performed to obtain 65% and foamed aluminum was produced, the ratio of air bubbles in the obtained casting was 0.5% by volume. Further, by controlling the volume increase rate of the cavity 5 by changing the opening distance of the first mold opening, it was possible to produce foamed aluminum having different bubble ratios.

  Furthermore, in the experiments by the present inventors, in order to produce high quality foamed aluminum, the volume increase rate of the cavity 5 was 1.0% or less, more preferably 0.7% or less. When the volume increase rate of the cavity 5 exceeded 1.0%, a disadvantage such as a lack of thickness occurred, and high quality foamed aluminum could not be produced.

30: Casting device,
40. Cast product made of foam metal,
1, 2 ... mold,
5 ... cavity,
6 ... Sleeve,
8 ... Plunger,
9 (10): Sealing means,
20 ... molten metal,
21 ... Bubbles.

Claims (2)

A method for producing a foam metal having bubbles in a metal base material using a mold,
Injecting molten metal containing dissolved gas into a closed mold cavity;
Sealing the inside of the cavity after pouring the molten metal;
Performing a first mold opening in a state in which the inside of the cavity is maintained, depressurizing the inside of the cavity, and bubbling the dissolved gas; and
A step of cooling the metal base material in which aeration has progressed;
Performing a second mold opening after cooling the metal base material to demold the foam metal from the mold;
A method for producing a foam metal, comprising:   The method for producing a foam metal according to claim 1, wherein the metal base material is aluminum, magnesium, zinc, brass, or an alloy thereof.

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