JP2020082157A - Molding die and molding method - Google Patents

Abstract

To provide a molding die that can obtain high-quality molded product with less shrinkage cavities generated.SOLUTION: The molding die, into which a heated molten material is pressurized and charged in order to obtain a coagulated object having a thin wall part and a thick wall part, comprises a first die, provided at an upstream side of a passage on which the molten material is charged, which forms a first cavity molding the thin wall part of the coagulated object, and a second die that forms a second cavity provided at a downstream side of the first cavity and communicated with the first cavity and molding the thick wall part of the coagulated object. The first die has coarse parts constituted of base materials that externally contact an inner wall partitioning the first cavity to support the wall and hollows formed around the base material. The coarse parts of the first die delay coagulation in the first cavity molding the thin wall part. Therefore, molten materials can be sufficiently supplied to the second cavity molding the thick wall part through the first cavity, so that generation of shrinkage cavities in the thick wall part is suppressed.SELECTED DRAWING: Figure 1B

Description

The present invention relates to a molding die or the like in which a heated melt is pressure-filled.

Die casting of metal, injection molding of resin, and the like are performed by press-filling a molten material obtained by heating and melting a raw material into a cavity of a mold, followed by cooling and solidification. As a result, even a product having a complicated shape can be efficiently manufactured while maintaining excellent dimensional accuracy.

WO2013/161396 Japanese Patent Laid-Open No. 11-348045

By the way, in a molded product (solidified product) obtained by cooling and solidifying a melt in a cavity of a mold, a casting defect such as a porosity (particularly a shrinkage porosity) may occur due to solidification shrinkage. In particular, shrinkage cavities are likely to occur in the thick wall portion that is connected to the downstream side of the thin wall portion that rapidly solidifies.

Conventionally, casting defects have been suppressed by devising and adjusting a plan, a molten material filling flow path, a molding condition, and the like.

In view of such circumstances, it is an object of the present invention to provide a molding die or the like that can obtain a high-quality molded product (solidified product) with few casting defects based on an idea different from the conventional one.

It should be noted that Patent Document 1 proposes a hollow mold for casting made of cast iron. Patent Document 1 also describes that the hollow mold is not a completely hollow mold but a honeycomb structure. However, the hollow mold of Patent Document 1 is intended for gravity casting of cast iron. And, in order to prevent chilling of the entire surface layer of the cast regardless of the shape of the cast and the flow path of the molten metal, only a hollow mold capable of reducing the cooling rate during solidification is adopted.

Patent Document 2 proposes to manufacture a metal mold having a temperature control circuit in which a coolant such as water flows by a three-dimensional modeling method (powder laminating method). However, Patent Document 2 aims at improving the degree of freedom in designing the temperature control circuit provided in the metal mold and improving the cooling performance by the mold. Moreover, the resin molded product obtained by using the mold is thin as a whole.

As described above, none of the patent documents describe or suggest a mold structure capable of suppressing casting defects such as shrinkage cavities.

As a result of intensive studies to solve the above-mentioned problems, the present inventor reduces the thermal conductivity in the vicinity of the inner wall of the cavity corresponding to the thin part of the molded product (solidified product) as a low-density rough part. I thought about that. It was also confirmed that such a mold significantly reduces shrinkage cavities in a thick portion continuous with a thin portion. The present invention described below has been completed by developing these results.

《Molding die》
(1) The present invention is a molding die in which a heated melt is pressure-filled in order to obtain a solidified product having a thin portion and a thick portion, the upstream side of a flow path for filling the melt. A first mold for forming a first cavity for molding a thin portion of the solidified material, and a thick mold portion of the solidified material for communicating with the first cavity located downstream of the first cavity. And a second mold forming a second cavity, the first mold comprising a base material circumscribing an inner wall defining the first cavity and supporting the inner wall, and a cavity around the base material. Is a molding die having a roughened portion.

(2) By using the molding die of the present invention (also simply referred to as “die”), it is possible to reduce or suppress casting defects such as shrinkage cavities generated in the thick portion. The reason for this is considered as follows.

The die of the present invention has the rough portion in the first die forming the first cavity corresponding to the thin portion. The rough portion contains cavities (voids, holes, etc.) and has a lower density than that of a solid case (a case of only a base material). Then, the vicinity of the inner wall of the first cavity, which is in contact with the rough portion, has a low heat capacity and/or a low thermal conductivity, and heat saturation is likely to occur.

Therefore, the cooling rate of the melt contacting the inner wall surface of the first cavity becomes small, and the solidification of the melt is delayed. That is, it is possible to delay the timing at which the first cavity, which serves as the flow path for filling the second cavity with the melt, is closed by the solidification of the thin portion. As a result, the melt having the fluidity, the pressure transmissibility and the like secured therein can be supplied to the second cavity for a longer period of time while passing through the first cavity. In this way, it is considered that solidification shrinkage of the melt in the second cavity is also reduced, and it becomes possible to form a thick wall portion with few casting defects such as shrinkage cavities.

(3) By the way, with the pressure filling of the melt, a considerable amount of surface pressure also acts on the inner wall surface of the first cavity in contact with the rough portion, but the surface pressure depends on the base material of the rough portion. Supported. The surface pressure that can be supported is adjusted by the structure/form of the rough portion, the apparent density (ρ) of the rough portion, or the relative density (ρ/ρ0) with respect to the true density (ρ0) of the base material. The heat conductivity near the rough portion is adjusted by the relative density of the rough portion, the thickness of the inner wall of the first cavity, and the like.

In order to secure a desired strength and heat transfer property in the vicinity of the rough portion, for example, the relative density of the rough portion may be 0.4 to 0.9, and further 0.5 to 0.8. If the relative density becomes too small, the strength of the rough portion will decrease. When the relative density is excessively high, the heat transfer property in the vicinity of the rough portion is enhanced, and the melt in the first cavity is likely to solidify.

The ratio (t/w) of the thickness (t) of the inner wall with which the rough portion is in contact with the interval (w) of the inner wall surfaces of the first cavity that face each other is, for example, 0.05 to 0.5, or even 0.15 to 0. It should be set to 0.35. If the inner wall thickness (ratio) is too small, the strength in the nearby area of Kurobe decreases. If the inner wall thickness (ratio) is excessively large, the heat transfer property in the vicinity of the rough portion is enhanced, and the melt in the first cavity is likely to solidify.

<<Molding method/Molded product>>
(1) The present invention can be understood as a molding method. That is, the present invention may be a molding method of obtaining a solidified product having a thin wall portion and a thick wall portion by cooling and solidifying the melted material filled under pressure into the above-mentioned molding die.

(2) The present invention can be understood as a molded product (solidified product) obtained by the molding method. This molded product has at least a thin portion and a thick portion. In the case of the present invention, the volume ratio (volume %) of the cavities (shrinkage cavities) present in the thick portion can be set to, for example, 1% or less, and further 0.5%. The volume ratio here is the ratio of the volume of shrinkage cavities to the volume of the second cavity. The molded product of the present invention may be a metal molded product (die casting, etc.) or a resin molded product.

《Others》
(1) "Upstream (side)" or "downstream (side)" in the present specification is specified along the flow direction of the melt to be pressure-filled. The direction in which the mold is arranged does not matter. For example, the first mold on the upstream side may be the lower mold and the second mold on the downstream side may be the upper mold.

The thin portion and the thick portion may have any specific thickness. Comparing the two, the portion having a relatively small thickness is the thin portion, and the portion having a larger thickness is the thick portion. The wall thickness is specified by the distance between the inner wall surfaces of the cavity (the minimum length of the inner wall surface in the normal direction).

(2) The rough part according to the present invention is sufficient if it exists in at least a part of the region of the first cavity where the solidification rate of the melt is desired to be reduced. It may be arranged so as to surround the entire inner wall of the first cavity, or may be arranged to circumscribe one or both of the inner walls facing each other.

It should be noted that the term "outside contact" as used in the present specification refers to a state of being in contact with the outside (the side opposite to the inside of the cavity). Each contacting part may be a dividable one or an integrally continuous one. For example, the inner wall and the rough portion circumscribing the inner wall may be configured by a combination of split dies or an integral type.

For the sake of convenience, the apparent density (volume %) of the rough portion in the present specification can be obtained as follows as an area% related to the cross section of the rough portion parallel to the inner wall surface of the cavity.
Apparent density = (cross-sectional area-cavity area) / (cross-sectional area) x 100
Here, the cross-sectional area is the total area of the observed cross section, and the cavity area is the total area occupied by the cavities present in the cross section. When the apparent density is calculated by the above equation, the size of the cross section is within the range of a square of 10 mm×10 mm at the maximum. Within that range, a cross section having an appropriate size to be calculated may be defined. At this time, the relative density={1-(cavity area)/cross-sectional area}. A region having a cross section whose relative density is 0.4 to 0.9 is a rough part.

(3) The inner wall referred to in this specification is a region that forms the inner wall surface of the cavity. The thickness of the inner wall with which the rough portion contacts is the shortest length between the inner wall surface and the inner end of the cavity of the rough portion (or the envelope described above) (usually the length along the normal direction of the inner wall surface).

(4) Unless otherwise specified, “x to y” in the present specification includes a lower limit value x and an upper limit value y. A range such as “a to b” may be newly established by setting any numerical value included in various numerical values or numerical ranges described in the present specification as a new lower limit value or upper limit value.

It is a front view and a sectional view showing an outline of a die-cast casting concerning an example. It is the front view and sectional drawing which show the rough shape of the metal mold|die used for the die casting casting. It is a schematic diagram which shows the rough part used for the solidification analysis. It is a solidification process diagram (die C1) obtained by analysis. It is a graph which shows the relationship between the inner wall thickness of a 1st cavity (inner wall surface space|interval: 10 mm), and the shrinkage cavity amount of a thick part. It is a graph which shows the relationship between the inner wall thickness of a 1st cavity (inner wall surface space|interval: 6 mm), and the shrinkage cavity amount of a thick part. It is a graph which shows the relationship between the relative density of the rough part of a 1st type, and the shrinkage cavity amount of a thick part. It is a schematic diagram which shows the rough part (die 2) of an actual 1st type|mold. It is an X-ray CT image of a thick part of a die cast casting obtained by using an actual die (die 2 and die C2).

One or more constituent elements arbitrarily selected from the specification may be added to the constituent elements of the present invention described above. The contents described in this specification can be applied to not only the molding die of the present invention but also the molding method and the molded product (solidified product) as appropriate. Which of the embodiments is the best depends on the target, the required performance and the like.

《Coarse part》
The rough part provided in the first mold is composed of a base material that circumscribes the inner wall that defines the first cavity and supports the inner wall, and a cavity around the base material. The rough portion can take various forms. The rough portion may have, for example, a porous shape, a lattice shape, or a groove shape. The base material may be, for example, a columnar or wall-shaped support. If such a support extends, for example, along the substantially normal direction of the inner wall surface that defines the first cavity, the strength and heat conductivity in the vicinity of the rough portion can be easily adjusted.

The cavities may be arranged substantially evenly with the base material. For example, when the base material is the above-mentioned support, the cavities may be formed substantially evenly on both sides or the periphery of each support. In this case, high strength and low heat transfer can be easily achieved at the same time as the entire rough portion.

The rough portion is formed by removal manufacturing, additional manufacturing, casting or the like. The removal manufacturing is performed, for example, by performing various cutting processes, laser processing, or the like on the raw material of the solid mold. The additional manufacturing is performed by, for example, a three-dimensional modeling method (3D printer). More specifically, it is performed by a layered manufacturing method using a metal powder (particularly a powder sintering layered manufacturing method). The powder sintering additive manufacturing method may be a powder bed fusion bonding method (PBF) or a directed energy deposition method (DED). PBF scans a high-energy beam (laser, electron beam, etc.) along a predetermined path every time a thin layer of raw material powder is laid, and repeatedly melts and solidifies the raw material powder to form a desired shape (bulk). Body) is how to get. DED is a method in which a raw material powder projected near the focal point of a high-energy beam is melted and solidified, and the melting and solidifying position is scanned (moved) to obtain a shaped article having a desired shape.

According to such a powder laminating method (particularly PBF), the degree of freedom in morphology of the rough portion can be increased. This makes it easy to adjust the strength and heat conductivity of the rough portion according to the specifications and the form of the mold and the molded product. Further, according to PBF, it is possible to form, for example, a support whose cross-sectional shape changes, a hollow support, a support in which unsintered remains inside, and the like. The hollow support is molded, for example, by taking out the unsintered powder from a preformed hole.

<<Type 1 and Type 2>>
The first mold and the second mold may be a split mold or a continuous integral mold. As long as the thin portion is molded by the first cavity and the thick portion is molded by the second cavity, the shape of each mold and each cavity does not matter.

The metals forming the first type and the second type may be the same or different. If the first metal forming the first mold has a lower thermal conductivity than the second metal forming the second mold, it is likely to delay the solidification in the first cavity in combination with the rough portion. If both metals are of the same type, alloy steel such as tool steel having excellent die life may be used.

When the two metals are different from each other, for example, a steel material (tool steel or the like) having a thermal conductivity of 15 to 35 W/m·k and further 20 to 30 W/m·k may be used as the first metal. As the second metal, for example, a steel material (general carbon steel or the like) having a thermal conductivity of 30 to 50 W/m·k, further 35 to 45 W/m·k may be used.

When the second mold is made of a solid body as a whole, its heat transfer property is improved. As a result, the solidification rate of the melt in the second cavity is increased, and shrinkage cavities in the thick portion are reduced.

<Melted material/solidified material>
The material to be the melt/solidified material may be metal or resin. The metal is, for example, an aluminum alloy, a magnesium alloy, or the like. A die cast casting (solidified product) is obtained by injecting a molten metal (melted product) of these metals into a die casting mold.

The resin is, for example, a thermoplastic resin. When the melt is injected into a molding die, a resin molded product (solidified product) is obtained.

The amount of shrinkage cavities generated in the thick wall portion of the casting when die casting was performed using various molds was evaluated by numerical analysis and measurement of the actual casting (referred to as "actual casting"). The present invention will be described in more detail based on these specific examples.

[First embodiment]
"model"
(1) An outline of a die casting casting (simply called "casting") is shown in FIG. 1A. This casting has a thin portion and a thick portion. The thin portion is on the upstream side where the molten metal is injected (pressurized filling), and is connected to the biscuit portion (solidified material of the injection sleeve). The thick portion is continuous with the thin portion and is on the downstream side (end side) of the thin portion. The thin portion and the thick portion have a constant thickness in the left-right direction of the front view (the depth direction of the AA sectional view). For convenience of explanation, the upper and lower sides and the left and right sides are the directions shown in the drawing.

(2) An outline of a die (molding die) used for die casting of the casting (simply referred to as “casting”) is shown in FIG. 1B. This mold includes a first mold and a second mold, each of which is composed of a plurality of split molds. The first mold internally has a first cavity corresponding to the thin portion. The second mold internally has a second cavity corresponding to the thick portion.

The injection sleeve is liquid-tightly connected to the upstream side of the first mold, and the second mold is liquid-tightly connected to the first downstream side. By driving the plunger incorporated in the injection sleeve, the molten metal supplied into the injection sleeve is pressurized and filled into the second cavity via the first cavity. The actual die casting is performed by setting the die on a vertical die casting machine. In this case, the first mold is the lower mold and the second mold is the upper mold.

(3) As shown in the BB cross-sectional view of FIG. 1B (simply referred to as “cross-sectional view”), the first mold is provided with rough portions near inner walls of the first cavity that face each other. Each rough portion is in contact with the outside of each inner wall and extends along the inner wall (in the left-right direction of the front view of FIG. 1B).

Various forms of the rough portion can be considered. An example is shown in the cross-sectional view of FIG. 1B. The rough portion is composed of a laminated tubular body in which cuboid (rectangular cross-section) cavities and supporting walls are alternately arranged in the vertical direction so as to circumscribe along the inner wall of the first cavity (see FIG. 4A). ..

In the present embodiment, a solid region connecting from the inner wall surface is called an inner wall, and a hollow (dispersion) region in which cavities circumscribing the inner wall are alternately arranged is called a rough portion. The distance (w) between the inner wall surfaces of the first cavity, the thickness (t) of the inner wall, and the width (c) of the rough portion are in the left-right direction (the normal direction of the inner wall surface of the first cavity) shown in the cross-sectional view of FIG. 1B. (See FIG. 4A). Further, the mold according to this example is a solid dense part (solid body) except for the rough part, unless otherwise specified.

"analysis"
(1) Conditions Solidification analysis by casting CAE (Computer Aided Engineering) was performed using the models shown in FIGS. 1A and 1B. TopCAST manufactured by Toyota Communication System Co., Ltd. was used as the analysis software. The analysis conditions were as follows.

The analysis range was the region D (100 mm×145 mm) shown by the alternate long and short dash line in FIG. 1B. Both sides in the depth direction of FIG. 1B were heat insulating elements. Thus, the above-mentioned analysis software executed by the calculation code of the three-dimensional analysis was used to perform the pseudo two-dimensional analysis in which the heat transfer in the depth direction of FIG. 1B was ignored. As shown in FIG. 1C, the rough portion was a low density portion (thickness: (50-t) mm) of relative density (r) circumscribing the inner wall (thickness: tmm) of the first mold. The rough portion is formed along the inner wall (60 mm in depth×about 60 mm in height) facing the first cavity.

The casting conditions were as follows.
Cast alloy: Al alloy (JIS ADC12/See Table 2 for physical properties)
Sleeve diameter: φ40 mm, injection speed: 0.15 m/s,
Casting pressure: 60 MPa, mold opening time: 4 s,
Molten metal temperature at injection (initial): 640°C, initial mold temperature: 25°C

The thermal conductivity in the mold was assumed to be proportional to the (relative) density. That is, the thermal conductivity of the base material (first metal): λ ₀ , the thermal conductivity of the rough portion: λ, and the relative density of the rough portion: r were set to λ∝r×λ ₀ . The heat transfer coefficient between the Al alloy and each mold was set to 19300 W/m ² ·K based on the experimental results. Further, a heat insulating state was established between the Al alloy and the injection sleeve/plunger.

(2) Method Analysis was performed by the difference method of the pseudo two-dimensional orthogonal coordinate system. The dimension of the dividing element was a square of 0.1 mm. The solidification analysis was started when each cavity in the mold was completely filled with the molten metal. Further, when the solid phase ratio in the first cavity (thin portion) reaches 0.9, the molten metal replenishment passage (filling passage) to the second cavity (thick portion) is blocked (closed). And

The amount of shrinkage cavities (area) generated in the thick portion was calculated from the amount of residual liquid phase in the second cavity at the time of the cutoff. The residual liquid phase amount was the sum (Σs) of the product of the area of each dividing element in the second cavity and the liquid phase ratio (1-solid phase ratio) at that time. Further, from the area ratio (Σs/S0) of the total area (S0) corresponding to the second cavity and the total area (Σs) corresponding to the residual liquid phase amount, the shrinkage cavity ratio (area%) in the thick portion Was calculated.

(3) Results As shown in Table 1, solidification analysis was performed for each mold in which the combination of each material of the first mold and the second mold and the presence or absence of the rough portion of the first mold was variously changed. Table 1 also shows the shrinkage cavities (area amount, area %) generated in the thick portion when each mold is used. In addition, the solidification process using the mold C1 is shown in FIG. 2 as an example.

In addition, here, the analysis was performed assuming that the inner wall spacing of the first mold (thickness of the thin portion): w=10 mm, the thickness of the inner wall: t=1 mm, and the relative density of the rough portion: r=0.5. In addition, the physical properties of the Al alloy (ADC12), which is a casting material, and the steel materials (tool steel: JIS SKD61, carbon steel: S45C) used for each mold are collectively shown in Table 2.

<<Evaluation>>
(1) As can be seen from FIG. 2, in the conventional mold, the solidification of the thin portion on the upstream side is completed long before the solidification of the thick portion is completed. Therefore, the supply of the molten metal to the thick portion and the pressurization of the thick portion are interrupted from the early stage before the solidification. As a result, it is considered that shrinkage cavities were easily generated in the thick portion. This can be seen from the amount of shrinkage cavities in the thick wall portion when using the mold C1 as shown in Table 1.

(2) On the other hand, as is clear from the comparison between the mold 1 and the mold C1 or the comparison between the mold 2 and the mold C3 shown in Table 1, when the rough part is provided in the first mold, the thick part It was found that the amount of shrinkage cavities in the rice was significantly reduced.

Further, as can be seen from the comparison between the molds C2 and C3, the material of the first mold (first metal) has a lower thermal conductivity than the material of the second mold (second metal) (conversely, the second metal is It has been found that the shrinkage amount is reduced when the heat conductivity is higher than that of the first metal. This tendency is the same when the rough part is provided in the first mold, as can be seen from the comparison between the mold 1 and the mold 2.

[Second Embodiment]
The influence of the first type inner wall spacing (thickness of the thin portion): w, the thickness of the inner wall: t, and the relative density of the rough portion: r on the shrinkage cavity amount of the thick portion is as follows. I looked it up.

"analysis"
The solidification analysis was carried out in the same manner as in the case of the first embodiment, using a mold (mold 1 or mold C1 shown in Table 1) in which both the first mold and the second mold are made of SKD61 as a model. However, the thickness (w) of the thin portion was set to 10 mm or 6 mm. The thickness (t) of the inner wall was changed within the range of 1 to 20 mm (t is 1, 2, 3, 4, 5, or 20). The relative density (r) of the rough part was changed in the range of 0.5 to 1. It should be noted that when r=1, there is no rough portion in the first die, which corresponds to the case where the die C1 is used as a model. The results thus obtained are summarized in FIGS. 3A, 3B and 3C (these are collectively referred to as “FIG. 3”).

<<Evaluation>>
As can be seen from FIG. 3, the smaller the inner wall thickness (t) and the smaller the relative density (r) of the rough portion, the smaller the shrinkage cavity amount. This tendency was the same even when the thickness (w) of the thin portion was changed.

However, as can be seen from FIGS. 3A and 3B, when the rough portion is provided, the thickness (t) of the inner wall is 0.5 or less of the thickness (w) of the thin portion (when w=10 mm, t is 5 mm. It was also found that the shrinkage cavity amount is remarkably reduced in the range where t is 3 mm or less when w=6 mm), 0.4 or less, and further 0.3 or less.

Further, as can be seen from FIG. 3C, it was also found that when the rough portion is provided, the shrinkage cavity amount is significantly reduced in the range where the relative density (r) is 0.9 or less, further 0.8 or less.

[Third Embodiment]
The mold 2 and the mold C2 shown in Table 1 were actually manufactured. Die casting was performed using these molds. The amount of shrinkage cavities in the thick portion of each actual die cast casting was measured and evaluated. Specifically, it is as follows.

(1) Mold As for the mold 2, the rough portion of the first mold is such that the cavity and the supporting wall (supporting member, base material) are vertically arranged as shown in FIG. 4A (enlarged view of P region in FIG. It is composed of laminated tubular bodies arranged alternately. The parts other than the cavity are solid bodies made of the first metal.

The interval (w) between the facing inner wall surfaces of the first cavity shown in FIG. 4A was set to 10 mm. The thickness (t) of the inner wall of the first mold forming the inner wall surface was 1 mm. The width (c) of the rough portion was 3 mm. The thickness of the cavity (la) and the thickness of the support wall (lb) were both 1 mm. As shown in FIG. 4A, when the cavity and the base material (supporting wall) are periodically repeated, the relative density r=Va/(Va+Vb) is calculated from the volume (Va) of each cavity and the volume (Vb) of each base material. And In the case of the present embodiment, both the cavity and the support wall have the same length as the depth (60 mm) of the first cavity, so r=la/(la+lb)=0.5.

The mold C2 is made of a solid material of the same metal (S45C) for both the first mold and the second mold.

By the way, the 1st type|mold of the metal mold|die 2 was manufactured by the additional processing which used the powder-sintered layered-molding method (powder bed fusion|bonding method: PBF) by making tool steel powder (SKD61 equivalent) into a raw material powder. As the 3D printer, SLM280HL manufactured by SLM Solutions was used. The first die and the second die of the die C2 and the second die of the die 2 were manufactured by cutting (removing) as in the conventional manner.

(2) Casting Die casting was actually performed under the casting conditions shown in the first embodiment. Insulation of the injection sleeve and the plunger was performed by installing a heat insulating material on their exposed surfaces.

(3) Observation/Measurement The thick part of each of the obtained castings was observed with an X-ray CT (Computed Tomography) device. Each CT image is shown in FIG. 4B. Each CT image was image-analyzed to determine the amount of shrinkage cavities (volume, volume %) in the thick portion. The volume% of the shrinkage cavity amount was calculated from the ratio between the volume of the second cavity and the shrinkage cavity amount (volume).

(4) Evaluation The measurement results shown in FIG. 4B showed the same tendency as the analysis results shown in Table 1. That is, by providing the rough portion on the first mold forming the thin portion, the amount of shrinkage cavities generated in the thick portion formed on the downstream side can be actually reduced.

As is clear from the above, it was confirmed that high-quality molded products with few shrinkage cavities can be obtained by molding using the molding die of the present invention.

Claims (8)

A molding die in which a heated melt is pressure-filled to obtain a solidified product having a thin portion and a thick portion,
A first mold for forming a first cavity for forming a thin portion of the solidified material on the upstream side of the melt filling channel;
A second mold which is downstream of the first cavity and communicates with the first cavity and which forms a second cavity for molding a thick portion of the solidified material,
The first mold is a molding die having a rough portion composed of a base material that circumscribes an inner wall that defines the first cavity and supports the inner wall, and a cavity around the base material. The molding die according to claim 1, wherein the rough portion has a relative density of 0.4 to 0.9, which is a density ratio with respect to a true density of a metal forming the base material. The ratio (t/w) of the thickness (t) of the inner wall in contact with the rough portion to the interval (w) of the inner wall surfaces of the first cavity facing each other is 0.05 to 0.5. Mold as described. The substrate comprises a columnar or wall-shaped support,
The molding die according to any one of claims 1 to 3, wherein the support member extends along a substantially normal direction of an inner wall surface defining the first cavity. The molding die according to claim 1, wherein the first metal forming the first die has a smaller thermal conductivity than the second metal forming the second die. The molding die according to claim 1, wherein the second die is a solid body. The molding die according to any one of claims 1 to 6, which is used for die casting of an aluminum alloy. A molding method for obtaining a solidified product having a thin-walled portion and a thick-walled portion by cooling and solidifying the melted material under pressure and filling into the molding die according to any one of claims 1 to 7.