JPH0938750A - Porous die material having excellent heat exchangeability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat exchangeability of a die member which is used for molding resins, casting nonferrous metals, etc., and consists of a porous metallic sintered compact. SOLUTION: This die member consists of the porous metallic body in which plural kinds of metallic particles varying in thermal conductivity are uniformly dispersed to coexist and which is a hot isotropic press sintered compact having porosity of 7 to 50% and pore diameter of <=500μm. The material kinds of plural kinds of the metals constituting the die member are preferably obtd. by combining the material kinds, such as iron or iron alloy, cobalt or cobalt alloy, or nickel or nickel alloy, having low thermal conductivity and the material kinds, such as copper or copper alloy, or aluminum or aluminum alloy, having the high thermal conductivity. The compounding ratio of the material kinds having the high thermal conductivity is 5 to 95% (vol.%).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous mold material having excellent heat exchange properties, which is used as a resin molding mold, a non-ferrous metal casting mold, and the like.

[0002]

Molds used for thermoforming of resins (injection molding, pressure molding, foam molding, blow molding, etc.) and casting of non-ferrous metals (for example, die casting of aluminum alloys) are molding and casting operations. By repeating the above, the mold temperature rises. If the mold temperature rises excessively, in resin molding, for example, the surface of the molded product is likely to be burned, and in a non-ferrous metal casting mold, troubles such as melting loss and seizure are likely to occur. Maintaining and controlling the mold temperature within a certain temperature range is important for efficient execution of molding / casting operations and ensuring product quality. A medium exchange passage for exchange is provided, and the mold temperature is controlled by the forced cooling action.

Further, the mold is provided with a degassing structure for discharging the gas generated from the air in the cavity and the resin or molten metal injected into the cavity to the outside, and each cycle of the molding / casting operation is performed. First, the gas is removed from the cavity. This is because, if the gas remains in the cavity, the gas in the product is entrained and product defects such as bubble transfer on the product surface occur. As a device for enhancing the gas venting effect, a porous sintered body was used as a mold constituent member instead of the conventional structure in which an air vent was provided.
A mold in which gas is vented through fine ventilation holes of a porous body has also been put into practical use, and various proposals have been made regarding the material type and the manufacturing method of the porous body (JP-A-60-130446).
JP, JP-A-3-239509, JP, 4-7
2004, JP 4-83603 A, JP 6-33112 A, etc.).

[0004]

The application of the porous body to the mold makes it possible to degas the cavity extremely effectively. However, on the other hand, the thermal conductivity of the mold is greatly reduced due to the heat insulation due to the porous body. Usually, this type of mold is applied with stainless steel, tool steel, etc., which are materials with low thermal conductivity, and as a result of overlapping the heat insulating properties of the porous body, the cooling action by the cooling device is diminished, It becomes difficult to maintain and control the mold within a desired temperature range. As a countermeasure against this, it is conceivable to strengthen the cooling action by changing the design of the cooling structure, such as adding a heat transfer medium supply pipe, but the structure becomes more complicated. In addition, it is often the case that it is difficult to obtain a uniform and sufficient cooling effect due to restrictions such as the forming location of the medium feeding pipe and the size and number of pipes due to the cavity shape of the mold.

In the resin molding operation, when the mold temperature rises and the molded product is burnt, painting is performed as a measure to restore the surface quality, and in the metal casting operation, melting damage and seizure of the mold are prevented. As a measure, a coating agent is applied to the surface of the cavity. However, none of them is unavoidable in the complexity of the process, and the obtained effect cannot be said to be sufficiently satisfactory. Alternatively, it is possible to set a waiting time for cooling / cooling for each cycle of the molding / casting operation, but it is inevitable that the operation efficiency / productivity is significantly reduced. The present invention aims to solve the above-mentioned problems relating to a mold for molding / casting, and has an excellent degassing as a porous body, and, while being a porous body, an improvement necessary for controlling the mold temperature is improved. The present invention provides a mold material having excellent thermal conductivity.

[0006]

Means for Solving the Problems The porous mold material of the present invention comprises a plurality of kinds of metal particles having different thermal conductivities uniformly dispersed and mixed, and has a porosity of 7 to 50% and a pore diameter of 500 μm or less. It is characterized in that it is composed of a metal porous body which is a pressure-pressurized sintered body.

The mold material of the present invention has a good degassing property because it is a porous body having a porosity of 7 to 50% and a pore diameter of 500 μm or less. The porous body is a mixture composed of a plurality of types of metal particles having different thermal conductivity,
It has a thermal conductivity adjusted according to the mixing ratio. That is, stainless steel or the like, which is usually used as a mold material, has a low thermal conductivity, but by mixing it with a material having a high thermal conductivity, a single material such as stainless steel can be obtained. It is possible to form a mold having a better heat exchange property than that of a porous material of a kind, and as the effect of improving the heat exchange property, it is easy to maintain and control the mold temperature by feeding the heat exchange medium. . The effect of improving heat exchange is not only when cooling and cooling the mold, but also when molding and casting operations
It enables efficient heating and heating when preheating is maintained at a temperature suitable for casting operation.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A plurality of types of metal materials having different thermal conductivities constituting the porous mold material of the present invention are classified into a type having a low thermal conductivity and a type having a low thermal conductivity. To be done. Examples of materials belonging to the group with low thermal conductivity κ are iron (κ: 73 W / mK, 300 ° C), iron-based alloys,
For example, SUS 304 stainless steel (κ: 19 W / m ・ K, 300 ℃)
, 12Cr stainless steel (κ: 24W / m · K, 100 ° C), cobalt (κ: 69W / m · K, 100 ° C), or cobalt alloy such as Stellite # 6 (κ: 15W / m · K, 20 ° C) ),
Stellite # 12 (κ: 15 W / m · K, 20 ° C), nickel (κ: 90 W / m · K, 300 ° C), or nickel alloy, such as In 625 (κ: 12 W / m · K, 400 ° C) , Nimonic (κ:
13W / mK, 100 ° C) and the like. These metal grades have desirable material properties such as corrosion resistance, strength, and wear resistance as mold materials for resin molding and nonferrous metal casting (aluminum die casting, etc.).

On the other hand, as an example of a metal material belonging to the group having a high thermal conductivity, aluminum (κ: 210 W / m · K, 3
00 ℃), or aluminum alloys such as Al-Mg-Si alloy (κ: 150 W / m · K, 100 ℃), copper (κ: 390 W / m · K,
300 ° C), or a copper alloy, such as a Cu-Zn alloy (κ:
200 W / mK, 100 ° C) and the like.

The porous mold material of the present invention has a sufficient effect of improving the thermal conductivity as the effect of mixing different kinds of metals.
It is effective to use a combination of materials such that the ratio of the thermal conductivity of the materials belonging to the low thermal conductivity group to the thermal conductivity of the materials belonging to the high thermal conductivity group is about 2 or more. When two or more types of materials belonging to each group are used in combination, the average thermal conductivity of each group is calculated according to a synthesis rule that takes into account the compounding ratio of multiple types of powder within each group, and the average heat The material types may be selected and combined so that the conductivity ratio is 2 or more. In a metal porous body composed of a material having a low thermal conductivity and a material having a high thermal conductivity,
The ratio (volume ratio) occupied by materials with high thermal conductivity is
It is preferable that the range is 5 to 95%. If it is 5% or less, the effect of improving the heat exchange property as a blending effect is poor, while 95% is less.
If it exceeds, it becomes difficult to secure the strength and wear resistance required for the mold. More preferably, 10
50%.

The porosity of the die material of the present invention is defined as 7 to 50%. When the porosity is less than 7%, the distribution of open pores for ensuring degassing is insufficient, and when the porosity exceeds 50%, the porosity is increased. This is because it becomes difficult to secure the mechanical strength required for the mold member, and the pore diameter is limited to 500 μm or less.
This is because if coarse pores exceeding that amount are distributed, the mechanical strength is greatly reduced, and the suitability as a die material is impaired. The pore distribution of this mold can be controlled by the particle size composition of the raw material powder, the sintering conditions, and the like.

The mold material of the present invention is formed as a hot isotropically pressurized sintered body by the sintering reaction under the uniform action of high pressure. This is because regardless of the shape (particularly, a complicated cavity shape having irregularities), it is possible to have a uniform porosity characteristic, and it is possible to impart good mechanical strength to the porous body. . The metal porous body of the mold of the present invention uses a mixture of plural kinds of metal powders as a sintering raw material, and is subjected to hot isostatic pressing (HI).
P treatment), for example, a method of filling a capsule with a sintering raw material powder mixture, degassing and sealing, and performing hot isostatic pressing (HIP treatment), or a sintering raw material powder mixture. In addition to forming into a powder compact by pressing, H
It is manufactured by a method such as IP treatment. It goes without saying that the sintering raw material powder mixture composed of a plurality of kinds of metal powders should be uniformly mixed in order to ensure the homogeneity of the sintered product.

As a manufacturing process of the die material of the present invention, when the step of filling the capsule with the sintering raw material powder and performing the HIP treatment is applied, the HIP treatment is performed at a temperature of about 0.2 to 0.
85mp ° K [mp is the melting point (absolute temperature) of the low melting point metal in the mixed powder], and the sintering reaction is preferably achieved under the pressurizing / heating conditions of a pressing force of about 0.5 to 150 MPa. You can After the HIP treatment, the sintered body is optionally subjected to a heat treatment at a temperature of about 0.5 to 0.98 mp ° K (mp is the same as above). This heat treatment is effective in strengthening the interparticle bond in the sintered body and increasing the mechanical strength of the sintered body without impairing the porosity of the sintered body formed by the HIP treatment. On the other hand, in the case of applying the step of HIPing the sintering raw material powder mixture after pressure molding, applying the cold isostatic pressing method to the powder pressure molding does not depend on the shape. It is effective in imparting good homogeneity to the molded product. In addition, the HIP treatment of the powder compact is
This may be performed as it is (capsule-free) without sealing in a capsule. When the capsule-free HIP process is performed, the pressure medium enters the voids of the powder compact and the high pressure of the hydrostatic medium acts from the outer surface and the inside of the powder compact as the effect. It is possible to sufficiently strengthen the interparticle bond by the sintering reaction while maintaining the porosity of the powder compact. The HIP treatment is suitably achieved under a treatment condition of a temperature of about 0.5 to 0.98 mp ° K (mp has the same meaning as above) and a pressure of about 0.5 to 150 MPa.

The mold material of the present invention constitutes a part or the whole of the mold. FIG. 1 shows a structural example of a mold 10 to which the mold material of the present invention is applied. Reference numeral 11 denotes a mold body member made of a porous metal sintered body, and the inner surface 11 ₁ thereof forms a cavity. Reference numeral 12 is an outer mold member (made of metal) combined with the back surface of the mold body member 11. Reference numeral 13 denotes a gas vent pipe line, and the gas vent pipe line 13 communicates with the pores of the porous body of the mold body member 11. Reference numeral 14 denotes a heat exchange medium feeding pipe line, and the medium feeding pipe line 14 in the drawing penetrates the outer mold member 12, but a main body member (porous body) 11
It is also possible to have a structure that penetrates through, and its design change is free.

[0015]

【Example】

[1] Production of porous mold member: A porous sintered body is obtained by using a uniform mixture of plural kinds of metal powders as a sintering raw material.
As a comparative example, a porous sintered body is obtained by using a metal powder of a single material as a sintering raw material. Table 1 shows the composition and production conditions of the raw material powder, and Table 2 shows the characteristics of the obtained porous sintered body.

(1) Raw material powder In Table 1, the symbols in the powder material type / mixing column are as follows (P _a1, P _a2, P _a3 : material types belonging to the high thermal conductivity group, P _b1, P _b2 : a material type belonging to the group of low thermal conductivity). P _a1 : SUS 304 stainless steel (κ 19 W / m ・ K, at300
℃), particle size −150 μm P _a2 : In 625 (κ 12 W / m · K, at 400 ℃), particle size −150
μm, P _a3 : Stellite # 12 (κ 15 W / m · K, at 20 ° C), grain size −150 μm, P _b1 : Copper (κ 390 W / m · K, at 300 ° C), grain size −100 μm
m, P _b2 : Aluminum (κ 233 W / m · K, at 300 ° C), grain size −100 μm, No. 5, No. 6 (combined use of two materials belonging to the group with high thermal conductivity) The ratio of the coefficients indicates the ratio of the calculated value and the thermal conductivity of the material having the high thermal conductivity, which is obtained by calculating the thermal conductivity of two types of low thermal conductivity according to the synthesis rule. No.12 (mixed use of two materials in the low thermal conductivity group) shows the ratio of the thermal conductivity of both materials.

(2) Manufacturing Process In Table 1, symbols A and B in the manufacturing process column are as follows. Step A: Fill the capsule (mild steel) with the raw material powder mixture
And degassed (1 × 10 ^-2Torr) and HIP processing
I do. Next, the capsule is removed, and the interparticle bonding of the sintered body is performed.
Heat treatment (or
Machine work was performed, and a rectangular porous sintered body (100
× 100 × 50, mm). Step B: The raw material powder mixture is filled in a rubber mold and subjected to CIP treatment.
And then HIP treatment (capsule
Free). After processing, add machining
A porous sintered body (shape and size are the same as above) is obtained.

(3) Properties of Porous Sintered Body Strength: Bending strength by 3-point bending test (test temperature: normal temperature) Abrasion resistance: Ratio of specific wear amount by Ogoshi-type rapid wear test Ventability: Gas pressure 0.2 Passing gas flow rate (cc / min · cm ² ) of the test piece (thickness 5 mm) at kgf / cm ²

As shown in Table 2, the porous sintered bodies of the invention examples (Nos. 1 to 6) were comparative materials No. 11 (stainless steel single material) and No. 12 (stainless steel-Ni alloy). It has a significantly higher thermal conductivity than composite materials). Further, it has high porosity, good degassing property, and also has mechanical strength, wear resistance and the like required as a constituent member of a mold for resin molding or non-ferrous metal casting.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

EFFECT OF THE INVENTION The mold material of the present invention has a good degassing property because it is a porous body, and at the same time, it is a porous body as a composite effect of plural kinds of metal particles having different thermal conductivity. With improved heat exchange performance, it is possible to effectively control the mold temperature by feeding the heat exchange medium, and to perform molding / casting cycles such as thermoforming of resin and casting of non-ferrous metal. It contributes to shortening, improving and stabilizing the quality of molded and cast products.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing an example in which a mold is formed using the mold material of the present invention.

[Explanation of symbols]

10: Mold 11: Mold Main Body Member (Metallic Porous Body) 11 ₁ : Cavity Surface 12: Outer Mold Member 13: Gas Venting Pipeline, 14: Heat Exchange Medium Feeding Pipeline

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryutaro Motoki 1-1-1, Nakamiya Oike, Hirakata City, Osaka Prefecture Kubota Hirakata Factory

Claims (4)

[Claims] 1. A plurality of kinds of metal particles having different thermal conductivities are uniformly dispersed and mixed, and have a porosity of 7 to 50% and a pore diameter of 500 μm.
A porous mold material having excellent heat exchange characteristics, which is characterized by comprising a metal porous body that is a hot isotropically pressurized sintered body of m or less. 2. A plurality of kinds of metal particles constituting a porous metal body belong to a group having a high thermal conductivity and a particle having a low thermal conductivity. The porous mold material having excellent heat exchange properties according to claim 1, wherein the ratio of the rates is 2 or more. 3. The metal particles belonging to the group having a low thermal conductivity are iron or iron alloys, cobalt or a cobalt alloy, or nickel or a nickel alloy, and the metal particles belonging to the group having a high thermal conductivity. 3. The mold material having excellent heat exchange properties according to claim 2, wherein the material type is copper or a copper alloy, or aluminum or an aluminum alloy. 4. The mold material excellent in heat exchange property according to claim 3, wherein the volume ratio of the metal particles having high thermal conductivity is 5 to 95%.