JP6838572B2 - Mold device - Google Patents

Description

The present invention relates to a mold device capable of molding an aluminum die casting member.

Conventionally, there is known a mold apparatus used in a die casting method capable of manufacturing a member having a desired shape by pressurizing a molten metal in a mold. For example, in Patent Document 1, a reducing organic acid or an organic acid salt is added to the surface of a mold in contact with a molten metal at a concentration of 0.01 wt% or more at the time of use and a release agent emulsion as a stock solution concentration. There is known a mold device for applying a mold release agent contained at a concentration equal to or less than a predetermined concentration, which is the stability limit of.

Japanese Unexamined Patent Publication No. 2007-118305

When molding a member made of aluminum, the cavity of the mold is filled with molten aluminum. In a mold device filled with molten aluminum, a nitriding treatment or a multi-layer coating of a heat-resistant ceramic layer is applied to the surface forming the cavity of the mold as a measure against aluminum welding and welding damage to the mold. However, in the case of the nitriding treatment, the nitrogen diffusion layer is gradually thermally decomposed by contact with the high-temperature molten aluminum, and thus lacks durability. Further, in the case of a multi-layer coating of a heat-resistant ceramic layer, when the molten aluminum penetrates into the coating starting from a film defect, the base of the coated mold is eroded by the reaction with the molten aluminum, so that the heat-resistant ceramic layer is peeled off. There is a risk.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a mold device that prevents welding with molten aluminum and prevents damage to the mold.

The present invention is a mold apparatus capable of manufacturing an aluminum die casting member (5), and includes a mold (10) and a molten metal supply unit (20).

The mold can form a cavity (100) that can be filled with the molten aluminum (4). The mold contains a base portion (111) made of iron and a dichrome trichrome film (114) provided on the cavity side of the base portion and contains 20% by weight or more of chromium and is formed on the surface (115) on the cavity side. It has a possible surface layer (113).

The molten metal supply unit can supply the molten aluminum to the cavity.
In the first aspect of the present invention, the mold has a concentration transition portion (112) provided between the base portion and the surface layer portion and formed so that the chromium concentration increases from the base portion to the surface layer portion. .. The base portion, the concentration transition portion, and the surface layer portion are integrally formed.
In the second aspect of the present invention, the mold apparatus further includes an oxidant supply unit (30) capable of supplying an oxidant to the cavity-side surface of the surface layer portion.

In the mold apparatus of the present invention, the surface layer portion provided on the cavity side of the base portion of the mold contains 20% by weight or more of chromium. This makes it possible to form a dichrome trichrome film on the surface of the surface layer portion on the cavity side, which is a passive film relatively dense with respect to the molten aluminum and has non-wetting resistance and corrosion resistance with respect to the molten aluminum. As a result, when the cavity is filled with the molten aluminum, welding of the base of the mold and the molten aluminum can be reliably prevented.

Further, the dichromium trioxide film on the surface layer may be peeled off due to the cooling / heating cycle of the mold, sliding when the aluminum die-cast member is taken out from the mold, or the like. In the mold apparatus of the present invention, even if the dichromium oxide film is peeled off, chromium moves to the surface of the surface layer portion inside the mold, and a new dichromium trioxide film can be formed. As a result, welding of the base of the mold and the molten aluminum can be prevented for a relatively long time, so that damage to the mold can be prevented and the life of the mold apparatus can be extended.

It is a schematic diagram of the mold apparatus according to 1st Embodiment. It is an enlarged view of the part II of FIG. It is a schematic diagram explaining the operation of the mold apparatus by 1st Embodiment. It is a schematic diagram explaining the operation of the mold apparatus by 1st Embodiment, and is the schematic diagram which shows the next state of FIG. It is a schematic diagram explaining the operation of the mold apparatus by 1st Embodiment, and is the schematic diagram which shows the next state of FIG. It is a photograph which shows the experimental result about the mold apparatus by 1st Embodiment. It is a photograph which shows the experimental result about the mold apparatus of the comparative example. It is a schematic diagram of the mold apparatus according to the 2nd Embodiment. It is a schematic diagram explaining the operation of the mold apparatus by 2nd Embodiment.

Hereinafter, a plurality of embodiments will be described with reference to the drawings. In the plurality of embodiments, substantially the same parts as those of the other embodiments are designated by the same reference numerals, and the description thereof will be omitted.

(First Embodiment)
The mold apparatus 1 according to the first embodiment will be described with reference to FIGS. 1 to 6. The mold device 1 is used for die-casting a member 5 (see FIG. 5) as an "aluminum die-casting member" made of aluminum. As shown in FIG. 1, the mold device 1 includes a mold 10 and a molten metal supply unit 20.

The mold 10 has a movable mold 11 and a fixed mold 12. The mold 10 forms a cavity 100 in which the molten aluminum can be filled by the movable mold 11 and the fixed mold 12.

The movable mold 11 is made of metal, for example, steel. The movable mold 11 is provided so as to be relatively movable with respect to the fixed mold 12 as shown by a white arrow F0. As shown in FIG. 1, the movable mold 11 has a first space 110 having an opening on the fixed mold 12 side. The first space 110 becomes a part of the cavity 100. FIG. 2 shows an enlarged view of the surface of the movable type 11 on the side in contact with the molten aluminum. The movable type 11 has a base portion 111, a concentration transition portion 112, and a surface layer portion 113. In the present embodiment, the base portion 111, the concentration transition portion 112, and the surface layer portion 113 are integrally formed.

The base 111 is a portion forming the skeleton of the movable type 11. As shown in FIG. 2, the base portion 111 is provided at a position relatively distant from the first space 110. In this embodiment, the base 111 is made of iron having a carbon concentration of 0.07% by weight or less.

The concentration transition portion 112 is a portion provided on the first space 110 side of the base portion 111. The concentration transition portion 112 is formed so that the chromium concentration increases in an inclined manner from the base portion 111 toward the surface layer portion 113 described later. In FIG. 2, the boundary between the base 111 and the concentration transition portion 112 is shown by the virtual line VL111.

The surface layer portion 113 is a portion provided on the first space 110 side of the concentration transition portion 112, and is a portion serving as an inner wall forming the first space 110. The surface layer portion 113 is formed so that the thickness is 30 μm or more and 200 μm or less. The surface layer portion 113 is formed so that the chromium concentration is 20% by weight or more by, for example, a chromasing method such as a vapor phase method or a powder method, or a heat diffusion method of a chromium-coated product. As a result, a dichromium trioxide (hereinafter referred to as “Cr ₂ O ₃ ”) film 114 is formed on the first space 110 side of the surface layer portion 113 (see FIG. 3). The Cr ₂ O ₃ film 114 is characterized in that the heat resistant temperature is 1350 ° C, which is higher than the aluminum casting temperature of 680 ° C, and there are no defects. In the present embodiment, the Cr ₂ O ₃ film 114 is formed so that the thickness is, for example, 3 nm or more. In FIGS. 3 to 5, the scale is changed so that it is easy to understand that _{the Cr 2} O _{3 film 114 is formed.} Further, FIG. 2 shows the boundary between the concentration transition portion 112 and the surface layer portion 113 by a virtual line VL112, and FIG. 3 shows the boundary between the Cr ₂ O ₃ film 114 and other parts in the surface layer portion 113. It is shown by the virtual line VL113.

The fixed mold 12 is made of metal, for example, steel. The fixed mold 12 is immovably fixed and has a second space 120 having an opening on the movable mold 11 side and a communication hole 121 as shown in FIG. The second space 120 becomes a part of the cavity 100. That is, the cavity 100 is composed of the first space 110 and the second space 120. The communication hole 121 communicates the second space 120 with the outside of the fixed mold 12.

The fixed type 12 has the same configuration as the movable type 11, and has a base portion, a concentration transition portion, and a surface layer portion. Each of the base portion, the concentration transition portion, and the surface layer portion of the fixed type 12 has the same characteristics as the base portion 111, the concentration transition portion 112, and the surface layer portion 113 of the movable type 11. The base portion, the concentration transition portion, and the surface layer portion of the fixed mold 12 are integrally formed.

The molten metal supply unit 20 is formed so that the molten aluminum can be supplied to the cavity 100 of the mold 10. The molten metal supply unit 20 supplies the molten aluminum to the second space 120 through the communication hole 121 of the fixed mold 12.

Next, the operation of the mold device 1 will be described. FIGS. 3 to 5 show changes in the enlarged view of the vicinity of the surface layer portion 113 of the movable mold 11 in the die casting method using the mold apparatus 1. Here, for convenience, the operation of the movable type 11 will be described, but the same applies to the fixed type 12.

_{As shown in FIG. 3, a Cr 2} O ₃ film 114 is formed on the surface of the surface layer portion 113 of the movable mold 11 and the surface layer portion of the fixed mold 12 in the mold apparatus 1 before the cavity 100 is filled with the molten aluminum. Has been done.

First, the movable mold 11 and the fixed mold 12 are combined to form the cavity 100. The molten aluminum supply 4 is supplied from the molten metal supply unit 20 to the mold 10 in which the cavity 100 is formed. The aluminum molten metal 4 supplied by the molten metal supply unit 20 is press-fitted into the cavity 100 and filled in the cavity 100. As shown in FIG. 4, the molten aluminum 4 press-fitted into the cavity 100 _{spreads over the surface 115 of the Cr 2} O ₃ film 114 opposite to the concentration transition portion 112. That is, the movable mold 11 and the fixed mold 12 come into contact with the molten aluminum by the _{Cr 2} O _{3 film 114.}

The molten aluminum 4 filled in the cavity 100 is solidified to form the member 5. When the member 5 is formed, the movable mold 11 and the fixed mold 12 are separated by moving the movable mold 11, and the member 5 is taken out from the mold 10. At this time, in the surface layer portion 113 of the movable mold 11 and the surface layer portion of the fixed mold 12, the Cr ₂ O ₃ film 114 peels off and falls off due to the movement of the member 5 as shown by the white arrow F1 in FIG.

After the member 5 is taken out from the mold 10, the Cr ₂ O ₃ film 114 is regenerated on the surface of the surface layer portion 113 as shown in FIG. The molten aluminum that is press-fitted into the cavity 100 for the production of the next member 5 spreads over the surface 115 _{of the regenerated Cr 2} O _{3 film 114.}

Here, changes in the surface of the mold on the cavity side after the molded member is taken out by press-fitting the molten aluminum into the cavity will be described with reference to FIGS. 6 and 7. The photographs shown in FIGS. 6 and 7 are cross-sectional photographs of the surface of the mold on the cavity side after the formed member is taken out from the cavity.

FIG. 6 shows a cross-sectional photograph of the vicinity of the surface of the mold 10 on the cavity 100 side in die casting using the mold device 1. In the mold apparatus 1 of the cross-sectional photograph shown in FIG. 6, the surface of the mold 10 on the cavity 100 side is subjected to a chromium permeation treatment.

FIG. 7 shows, as a comparative example, in die casting using a mold device (hereinafter, referred to as “mold device of comparative example”) which does not have a configuration corresponding to a surface layer portion and a concentration transition portion of the mold device 1. A cross-sectional photograph of the vicinity of the surface of the mold on the cavity side is shown. In the mold apparatus of the comparative example of the cross-sectional photograph shown in FIG. 7, the surface of the mold on the cavity side is subjected to nitriding treatment.

In the cross-sectional photograph of the vicinity of the surface of the mold device of the comparative example shown in FIG. 7, the surface of the mold (the portion indicated by the solid arrow A7 in FIG. 7) is completely eroded, so that the mold is uneven. I understand. On the other hand, in the cross-sectional photograph of the vicinity of the surface of the mold apparatus 1 shown in FIG. 6, no surface erosion was confirmed and the surface was in a relatively flat state (the portion indicated by the solid arrow A6 in FIG. 6). In addition, pitting corrosion due to molten aluminum was not confirmed.

In the mold apparatus 1 according to the first embodiment, the surface layer portion 113 provided with the cavity 100 side of the base portion 111 in the mold 10 contains 20% by weight or more of chromium. As a result, it is possible to form _{a Cr 2} O ₃ film on the cavity 100 side of the surface layer portion 113, which is a passive film relatively dense with respect to the molten aluminum 4 and has non-wetting resistance and corrosion resistance with respect to the molten aluminum 4. It has become. As a result, the mold apparatus 1 can surely prevent welding of the base 111 of the mold 10 and the molten aluminum 4.
Further, in the mold apparatus 1 according to the first embodiment, the surface of the surface layer portion of the mold 10 is maintained in a relatively flat state as shown in FIG. As a result, the dimensional accuracy can be improved while maintaining the appearance quality of the member 5 to be molded.

Further, in the mold apparatus 1 according to the first embodiment, when the member 5 formed in the cavity 100 is taken out from the mold 10, the Cr ₂ O ₃ film 114 formed on the surface layer portion 113 may be peeled off. .. In the mold apparatus 1 according to the first embodiment, chromium can move to the surface of the surface layer portion 113 inside the mold 10 to form a _{new Cr 2} O _{3 film 114.} As a result, the mold apparatus 1 according to the first embodiment can prevent welding of the mold 10 and the molten aluminum 4 for a relatively long time. Therefore, it is possible to prevent the mold 10 from being damaged and extend the life of the mold device 1. Further, since welding of the mold 10 and the molten aluminum 4 can be prevented for a relatively long time, the man-hours for maintaining the mold 10 can be reduced.

In the mold apparatus 1 according to the first embodiment, the concentration transition portion 112 is formed so that the chromium concentration increases obliquely from the base portion 111 toward the surface layer portion 113. Thereby, in the first embodiment, it is _{possible to prevent the Cr 2} O ₃ film 114 from being easily peeled off from the mold 10 due to thermal stress.

In the mold apparatus 1 according to the first embodiment, the surface layer portion 113 is formed so that the thickness is 30 μm or more and 200 μm or less. This is because when the thickness of the surface layer portion 113 is thinner than 30 μm, the Cr ₂ O ₃ film 114 is difficult to be regenerated, and when the thickness of the surface layer portion 113 is thicker than 200 μm, the surface layer portion 113 becomes hard and the Cr ₂ O ₃ film 114 Is easy to peel off from the surface layer portion 113. _{Therefore, in the first embodiment, the Cr 2} O ₃ film 114 can be appropriately maintained by setting the thickness of the surface layer portion 113 to 30 μm or more and 200 μm or less.

Further, in the mold apparatus 1 according to the first embodiment, the bases of the movable mold 11 and the fixed mold 12 have a carbon concentration of 0.07% by weight or less. This makes it possible to prevent the chrome contained in the concentration transition portion on the cavity 100 side of the base from being captured by the carbon at the base. Therefore, in the first embodiment, the chromium concentration in the concentration transition portion and the surface layer portion can be maintained at a desired concentration.

(Second Embodiment)
Next, the mold apparatus according to the second embodiment will be described with reference to FIGS. 8 and 9. The second embodiment is different from the first embodiment in that it includes an oxidizing agent supply unit.

The mold apparatus 2 according to the second embodiment of the present invention will be described with reference to FIGS. 8 and 9. The mold device 2 includes a mold 10, a molten metal supply unit 20, and an oxidant supply unit 30.

The oxidant supply unit 30 has an oxidant tank 31 and an injection nozzle 32.

The oxidant tank 31 is provided outside the mold 10. The oxidant tank 31 stores an oxidizing acid capable of reacting with a chromium component contained in the mold 10 _{to generate Cr 2} O ₃ , such as an organic acid such as nitric acid, sulfuric acid, or acetic acid.

The injection nozzle 32 is connected to the oxidant tank 31 via a pipe 33. The injection nozzle 32 is provided so as to be movable relative to the mold 10. As shown in FIG. 9, the injection nozzle 32 is movable so as to be located between the movable mold 11 and the fixed mold 12 in a state where the movable mold 11 and the fixed mold 12 are separated from each other. The injection nozzle 32 has a plurality of injection pipes 321. The injection pipe 321 can inject the oxidizing agent of the oxidizing agent tank 31 onto the surface 115 of the surface layer portion 113 of the movable type 11 and the surface 125 of the surface layer portion of the fixed mold 12 on the second space 120 side.

In the mold apparatus 2, in the step of molding the member 5, the movable mold 11 and the fixed mold 12 are separated from each other as shown in FIG. 9 before _{the Cr 2} O _{3 film 114 is significantly dropped.} The injection nozzle 32 is inserted between the 11 and the fixed mold 12. The inserted injection nozzle 32 injects an oxidant from a plurality of injection tubes 321 onto the surfaces of the movable type 11 and the fixed type 12 on the cavity 100 side (two-dot chain line IJ9 in FIG. 9). After that, the mold 10 and the oxidizing agent are heated by the heat of the molten aluminum, and Cr ₂ O ₃ films 114 are formed on the surfaces 115 and 125 of the movable mold 11 and the fixed mold 12 on the cavity 100 side.

In the mold apparatus 2 according to the second embodiment, in the step of molding the member 5, an oxidizing agent is supplied to the surfaces 115 and 125 according to the states of the surfaces 115 and 125 on the cavity 100 side of the movable mold 11 and the fixed mold 12. Cr ₂ O ₃ film 114 is positively formed. Thereby, by _{regenerating the Cr 2} O ₃ film 114 or _{strengthening the already formed Cr 2} O ₃ film 114, welding of the base 111 of the mold 10 and the molten aluminum 4 is surely prevented. Can be done. Therefore, in addition to the effects of the first embodiment, the second embodiment can further extend the life of the mold device 1.

(Other embodiments)
In the above-described embodiment, the mold has a concentration transition portion between the base portion and the surface layer portion. However, the concentration transition part may not be provided.

In the above-described embodiment, the base portion, the concentration transition portion, and the surface layer portion are integrally formed. However, it does not have to be one. For example, a high-concentration chromium material may be attached to the surface layer of the base to improve the adhesion by heat diffusion or the like. At this time, the base may be a member having a relatively high carbon concentration.

In the above-described embodiment, the concentration transition portion is formed so that the chromium concentration increases in a gradient from the base portion to the surface layer portion. However, the change in the concentration of the concentration gradient portion is not limited to this. It suffices that the chromium concentration is continuously changed between the surface layer portion having a chromium concentration of 20% by weight or more and the base portion having a relatively low chromium concentration.

In the above-described embodiment, the surface layer portion has a thickness of 30 μm or more and 200 μm or less. However, the thickness of the surface layer portion is not limited to this.

In the above embodiment, the base has a carbon concentration of 0.07% by weight or less. However, the carbon concentration at the base is not limited to this. At this time, the carbon concentration may be 0.07% by weight or less only in the portion of the base on the concentration transition layer side, for example, by decarburizing the portion. Further, even if the steel has a carbon concentration of about 0.4% by weight, the surface layer of the chromium layer is permeated and adhered to the base interface of the mold by plating the surface on the space side of the steel with chromium and then heating the steel. _{The Cr 2} O ₃ film formed on the mold can prevent welding of the base of the mold and the molten aluminum for a relatively long time.

In the second embodiment, the oxidant is injected by the injection tube. However, the method of supplying the oxidizing agent to the surface of the mold on the cavity side is not limited to this. For example, an oxidizing agent may be applied to the surface of the mold on the cavity side.

As described above, the present invention is not limited to such an embodiment, and can be implemented in various embodiments without departing from the gist thereof.

1,2 ... Mold device 4 ... Aluminum molten metal 5 ... Member (aluminum die-cast member)
10 ... Mold 20 ... Molten metal supply part 100 ... Cavity 111 ... Base 113 ... Surface layer 114 ... Dichromium trioxide film 115 ... Surface

Claims (5)

A mold device capable of manufacturing an aluminum die casting member (5).
A cavity (100) capable of filling the molten aluminum (4) can be formed, and the base portion (111) formed of iron, the cavity provided on the cavity side of the base portion and containing 20% by weight or more of chromium. A mold (10) having a surface layer portion (113) capable of forming a dichrome trichrome film (114) on the side surface (115, 125), and a mold (10).
A molten metal supply unit (20) capable of supplying molten aluminum to the cavity, and
Equipped with a,
The mold has a concentration transition portion (112) provided between the base portion and the surface layer portion and formed so that the chromium concentration increases from the base portion toward the surface layer portion.
The base, the concentration transition portion, and said surface portion, a mold apparatus that is formed integrally. A mold device capable of manufacturing an aluminum die casting member (5).
A cavity (100) capable of filling the molten aluminum (4) can be formed, and the base portion (111) formed of iron, the cavity provided on the cavity side of the base portion and containing 20% by weight or more of chromium. A mold (10) having a surface layer portion (113) capable of forming a dichrome trichrome film (114) on the side surface (115, 125), and a mold (10).
A molten metal supply unit (20) capable of supplying molten aluminum to the cavity, and
An oxidant supply unit (30) capable of supplying an oxidant to the surface of the surface layer on the cavity side, and
Mold device. The mold apparatus according to claim 2 , wherein the oxidizing agent is an oxidizing acid. The mold apparatus according to any one of claims 1 to 3, wherein the surface layer portion has a thickness of 30 μm or more and 200 μm or less. The mold apparatus according to any one of claims 1 to 4 , wherein the base has a carbon concentration of 0.07% by weight or less.

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