JP2003260558A - Die casting mold and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve productivity and to reduce costs by eliminating as much damages to a mold as possible occurring when molten metal under high pressure collides with the mold during casting molten metal into the mold, thereby having a longer service life of the mold. <P>SOLUTION: The die material surface is coated with Co-Cr alloy via an intermediate metal coating layer to reduce volume damage amount, thereby having a longer service life of the mold. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die-casting mold including members such as a sleeve, a cylinder plunger, an extrusion pin, and a mold core which are in direct contact with a molten metal to be cast into a mold and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recently, a metal such as aluminum, aluminum alloy, magnesium, magnesium alloy or the like, which is light and has good thermal conductivity, is often used for housings of communication information devices such as personal computers and various electric and electronic control devices. There is. Generally, these housings are often manufactured by a die casting method.

Die casting is a method in which a molten metal is pressed into a precisely made mold at high temperature and high pressure for a very short time to cast it.
This is a casting method that can mass-produce castings with high precision and excellent casting surface in a short time. The die used for this die casting requires high strength and excellent wear resistance, and is an alloy tool steel made of Fe-based alloy, which is a conventional hot die material.
SKD steels such as 6 and SKD61 are commonly used.

In such a die cast mold,
In order to improve productivity and reduce costs, it is required to extend the life of the mold as much as possible.Therefore, after the mold material is engraved, it is subjected to heat treatment such as quenching and tempering and nitriding treatment. ing.

[0005]

[Problems to be Solved by the Invention]
Especially in die casting of magnesium or magnesium alloy, when molten magnesium is cast into the mold at high speed and high pressure, the molten metal directly collides with the mold inlet part, pins, etc. and damages these members. was there.
Therefore, there is a problem that the life of the mold becomes short, which causes a decrease in productivity and a high cost.
There has been a demand for a die having excellent wear resistance and a long life.

In view of the above points, an object of the present invention is to provide a die-casting mold which has less damage due to collision of molten metal and has a longer life, and a manufacturing method thereof.

[0007]

The invention of the die-casting mold according to claim 1 of the present invention is characterized in that the surface of the mold material is coated with a Co-Cr alloy through an intermediate metal coating layer. . According to the present invention, the number of life shots is large and the life can be improved as compared with a conventional die-casting die not coated with a Co-Cr alloy.

The invention of the method for producing a die-casting mold according to claim 2 of the present invention comprises a step of coating the surface of the mold material with a stainless steel material as an intermediate metal coating layer, and Co-on the intermediate metal coating layer. And a step of coating a Cr-based alloy. According to the present invention, the intermediate metal coating layer prevents the generation of cracks in the mold during overlaying the alloy coating or cooling after the coating.

The invention of the method for producing a die-casting die according to claim 3 of the present invention is the method for producing a die-casting die according to claim 2, wherein the die material is 100 ° C. to 800 ° C.
C on the intermediate metal coating layer while heating in the temperature range of
It is characterized by coating an o-Cr alloy. According to this invention, generation of cracks in the mold is prevented in the alloy coating build-up step.

The invention of the method for manufacturing a die-casting mold according to claim 4 of the present invention is the method for manufacturing a die-casting mold according to claim 2 or 3, wherein C using TIG welding is used.
It is characterized by coating an o-Cr alloy. According to the present invention, the number of life shots is large and the life can be improved as compared with a conventional die-casting die not coated with a Co-Cr alloy.

The invention of the method for producing a die-casting die according to claim 5 of the present invention is the method for producing a die-casting die according to claim 2 or 3, wherein Co-Cr is used by powder overlay welding. It is characterized in that it is coated with a system alloy. According to the present invention, the number of life shots is large and the life can be improved as compared with a conventional die-casting die not coated with a Co-Cr alloy.

The invention of the method for producing a die-casting mold according to claim 6 of the present invention comprises a step of coating the surface of the die material with an intermediate metal coating layer, and a particle diameter of 1 on the intermediate metal coating layer.
Co-Cr alloy powder of 0 μm to 150 μm is coated by a high speed flame spraying method or an ultra high speed flame spraying method. According to this invention, the air resistance at the time of thermal spraying is small, and it is possible to perform the construction at high speed and high impact.

According to a seventh aspect of the present invention, there is provided a method for producing a die-casting die according to the sixth aspect, wherein the die material coated with a Co--Cr alloy is vacuumed. It is characterized by having a diffusion adhesion heat treatment step of performing heat treatment at 800 ° C. to 1100 ° C. for 30 minutes to 10 hours in a furnace. According to the present invention, it is possible to prevent the pores from remaining in the alloy layer and the formation of the opening at the interface between the die material and the alloy layer.

The invention of the method for producing a die cast mold according to claim 8 of the present invention is the method for producing a die cast mold according to claim 6, wherein the center line average roughness of the surface of the die material is 5 μm to 20 μm. It is characterized by having a blasting treatment step for making the surface roughness of the. According to this invention, peeling during spraying is prevented and damage to the die material is prevented.

The invention of the method for producing a die-casting die according to claim 9 of the present invention is the method for producing a die-casting die according to claim 6, wherein the surface temperature of the die material is cooled to 200 ° C. or lower. , Co—Cr alloy powder is sprayed onto the surface of the die material. According to this invention, oxidation of the alloy powder is prevented and a good coating layer is formed.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the present invention, in die casting of a magnesium alloy casing, as a result of elucidating a damage mechanism of a mold actually damaged by collision of molten metal, it was found that a damage form similar to cavitation due to shock wave is exhibited. .

Therefore, the SKD used in the hot die
Mold material A made of 61 steel material, mold material B made by nitriding SKD61 steel, mold material C coated with CrN (chromium-nitrogen) ceramic thin film by ion plating method on SKD61 steel, ultra high speed frame on SKD61 steel Mold material D coated with Co (cobalt) -29% Cr (chromium) -5% W (tungsten) -1% C (carbon) alloy by a thermal spraying method,
Coated with SIG61 steel by TIG welding
29% Cr (Chromium) -4.5% W (Tungsten) -1
Mold materials E coated with% C (carbon) alloy were manufactured, these mold materials were evaluated by a high frequency cavitation test in water, and the volume damage amounts of the mold materials were compared.

The results are shown in FIG. As can be seen from FIG. 1, mold material A and mold material C have the largest volume damage amount, and mold material B is about 1/4 of the volume damage amount as compared with mold material A made of SKD61 steel material. is there.

On the other hand, the die material D has a volume damage amount of about 1/7 that of the die material A, and about 1/2 of that of the die material B.
The amount of volume damage was. Further, the die material E has a volume damage amount of about 1/20 as compared with the die material A, and has a volume damage amount of about 1/20 as compared with the die material B.
The amount of volume damage is / 4.

From the above, it was revealed that the volumetric damage amount of the die material coated with the Co (cobalt) -Cr (chromium) -based alloy was much smaller than that of other die materials, and therefore the life was greatly improved. .

Next, the coating method of the Co--Cr type alloy in the present invention will be explained. The alloy coating means is roughly classified into a weld overlay method and a welding method. As for the weld overlay method, there are two means, the TIG weld overlay method and the weld overlay method using powder.

In the coating method by the TIG welding overlay method, first, a visual appearance inspection of a die material that has been engraved is performed, and then the coated surface of the die material is degreased and washed with acetone or the like. Next, the die material is preheated in a temperature range of 100 ° C. to 800 ° C. with a gas burner, an electric furnace or the like. The reason for performing this preheating is to prevent cracks from being generated in the mold material itself in the step of coating the mold material with the Co—Cr alloy. Where the temperature is 100 ° C
If the temperature is less than 100 ° C, the preheating effect is thin, and if the temperature exceeds 800 ° C, the characteristics of the mold material change, so the preheating temperature is 100 ° C to 8 ° C.
The temperature range was 00 ° C. More preferably, the preheating temperature is about 600 ° C. In the TIG welding build-up, it is possible to directly build up a Co-Cr alloy welding rod on the mold material, but more preferably, the mold material is preliminarily coated with stainless steel to form an intermediate metal coating layer. The two-layer structure in which the Co—Cr alloy is built up via the intermediate metal coating layer can completely prevent cracking of the mold material during the buildup work or cooling after the work.

Next, in the coating method by welding build-up using powder, in the same manner as above, first, a visual appearance inspection of the die-molded die material is performed, and then the coated surface of the die material is degreased and washed with acetone or the like. To do. Next, the mold material is heated to 100 with a gas burner or electric furnace.
Preheat in the temperature range of ℃ to 800 ℃. In this case as well, it is more preferable that a two-layer structure in which a metal material is preliminarily coated with stainless steel to form an intermediate metal coating layer, and a Co—Cr alloy is deposited on the intermediate metal coating layer to prevent cracking after construction. Can be prevented.

On the other hand, Co-Cr produced by high-speed flame spraying
A method of coating the system alloy will be described. First, after performing a visual appearance inspection of the die-molded die material, the coated surface of the die material is degreased and washed with acetone or the like. After that, the coated surface of the mold material is blasted by using, for example, alumina grit to uniformly roughen the coated surface of the mold material. At this time, the center line average roughness Ra of the coated surface of the mold material is set to 5 μm to 20 μm, more preferably 7 μm to 15 μm to prevent peeling of the coating layer during thermal spraying and The damage can be reduced.

After such pretreatment is completed, the surface of the die material is sprayed with Co--Cr alloy powder. In this thermal spraying process, the thermal spraying powder of Co-Cr alloy is subjected to high speed flame spraying or ultra high speed flame spraying at a high speed of 350 m / sec to 1500 m / sec, more preferably 650 m / sec to 1200 m / sec. By spraying, a dense coating layer can be obtained. As the Co—Cr alloy powder, spherical powder having a particle diameter of 10 μm to 150 μm, more preferably 25 μm to 65 μm is used.

When such a powder shape is used, since the air resistance at the time of thermal spraying is small, a dense coating layer can be obtained by applying at a high speed and a high impact. On the other hand, the particle size is 10
When the particle diameter is 150 μm or more, it is easy to accelerate with the flame spraying frame, and it is possible to realize high-speed and high-impact construction, and when the particle size is 150 μm or less, it is easy to melt and the thermal spraying efficiency can be increased. Therefore, a finer coating can be realized by making the particle diameters uniform.

Further, in the above-mentioned thermal spraying process, air or an inert gas such as nitrogen gas, helium gas or argon gas is blown onto the die material to cool the die material to a temperature of less than 200.degree.

This is because when the temperature of the die material is 200 ° C. or higher, the alloy powder is oxidized and a good coating layer cannot be obtained. Obtainable.

Although coating by ultra-high speed flame spraying can be performed in this manner, more preferably, diffusion adhesion heat treatment is performed after coating. In this case, the die material coated with Co—Cr alloy powder is placed in a vacuum furnace at 800 ° C. to 1100 ° C.
C., more preferably 900.degree. C. to 1050.degree. C., for 30 minutes to 10 hours, more preferably 2 hours to 6 hours.

This is because if the heat treatment at a temperature of less than 800 ° C. or less than 30 minutes, the diffusion adhesion heat treatment is insufficient, defects such as pores remain in the alloy layer, and if the heat treatment at a temperature of more than 1100 ° C. or 10 hours is performed, the die material is This is because defects such as openings are formed at the interface between the alloy layer and the alloy layer.

Hereinafter, examples in which the present invention is specifically carried out will be further described. As shown in FIG. 2, the mold material 1 has a length of 6
Using SKD61 steel of 0 mm, 90 mm in width, and 80 mm in height, the surface on which the magnesium alloy molten metal collides is formed into a tapered processing surface 2, and then stainless steel SUS309 is welded to the processing surface 2 to form a 2 mm thick surface. Was machined to the intermediate metallization layer 3 of. On this intermediate metal coating layer 3, T
A Co-29% Cr-4.5% W-1% C alloy welding rod was built up to a thickness of 8 mm by IG welding to form a coating layer 4. After that, flattening, punching and grooving were performed to manufacture a mold core.

The manufactured mold core is installed in a mold part of a machine for die-casting a magnesium alloy case for a personal computer, and the case is manufactured on an actual line until the mold core is damaged. The number of life shots (the number of castings) was measured.

Similarly, using the above SKD61 steel, Co
-29% Cr-5% W-1% C alloy powder was coated to a thickness of 8 mm by ultra-high speed flame spraying, subjected to diffusion adhesion heat treatment at 1050 ° C x 2 hours in a vacuum furnace, and then flattened and drilled. Then, groove processing was performed to manufacture a mold core.

For comparison, mold cores made of SKD61 steel, mold cores subjected to nitriding, and mold cores having CrN ion-plated were manufactured, and the number of life shots in the actual line was measured in the same manner. did.

The results are shown in FIG. 3. As is clear from the results, the life shots of the mold cores I and II coated with the Co--Cr alloy according to the present embodiment are normally used. It can be seen that the lifespan is significantly increased compared to the nitriding-treated mold core III, the mold core IV coated with CrN, and the mold core V of the SKD61 steel material.

Although the mold core has been described in the concrete examples described above, the present invention is not limited to the mold core, and a molten metal such as a sleeve, a cylinder plunger, an extrusion pin, or the like may be used. Can be implemented in a mold that includes other members that are in direct contact with.

[0037]

As described above, according to the present invention, since the surface of the die material is coated with the Co-Cr alloy through the intermediate metal coating layer, the damage due to the collision of the molten metal is reduced and the life is reduced. It is possible to obtain a die-casting mold having improved temperature and a manufacturing method thereof.

[Brief description of drawings]

FIG. 1 is a view showing a result of an underwater high frequency cavitation test according to the present invention.

FIG. 2 is a view showing a cross section of a mold core according to the present invention.

FIG. 3 is a diagram showing the number of life shots of a die insert according to the present invention.

[Explanation of symbols]

1 ... Mold material, 2 ... Processed surface, 3 ... Intermediate metal coating layer, 4 ... Coating layer.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B23K 9/167 B23K 9/167 A C23C 4/08 C23C 4/08 (72) Inventor Kairoku Yoshinori Kanagawa Yokohama 33, Isogo-cho, Isogo-ku, Japan Incorporated company, Toshiba Production Technology Center (72) Inventor Tadashi Takahashi 5-14-25 Ryoke, Kawaguchi City, Saitama Prefecture Toshiba Chemical Co., Ltd. Kawaguchi Factory (72) Inventor Kazutoshi Takaishi 2-4, Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Inside the Keihin Plant, Toshiba Corporation (72) Masayuki Ishikawa 2--4, Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa Prefecture (72) Masahiro Saito, Inventor 2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Keihin Plant (72) Inventor Shinji Nakata Isogo-ku, Yokohama-shi, Kanagawa Isogo-cho 33 address Co., Ltd. Toshiba production technology center in the F-term (reference) 4E001 AA03 BB07 CA03 DG04 4E093 NA01 NB09 4K031 AA03 AB02 AB08 BA01 BA05 CB18 CB22 DA01 EA11 FA01

Claims (9)

[Claims] 1. A method for forming C on the surface of a die material through an intermediate metal coating layer.
A die-casting mold characterized by being coated with an o-Cr alloy. 2. A die-cast metal comprising a step of coating a surface of a die material with a stainless material as an intermediate metal coating layer, and a step of coating the intermediate metal coating layer with a Co—Cr alloy. Mold manufacturing method. 3. The die-cast mold according to claim 2, wherein the intermediate metal coating layer is coated with a Co—Cr alloy while heating the mold material in a temperature range of 100 ° C. to 800 ° C. Production method. 4. The method for producing a die-casting mold according to claim 2, wherein the Co—Cr alloy is coated by using TIG welding. 5. The method for producing a die-casting mold according to claim 2, wherein the Co—Cr alloy is coated by using powder overlay welding. 6. A step of coating an intermediate metal coating layer on the surface of a die material, and a high-speed flame spraying method or an ultra-high-speed flame coating of a powder of a Co--Cr alloy having a particle diameter of 10 μm to 150 μm on the intermediate metal coating layer. And a step of coating using a thermal spraying method. 7. A diffusion adhesion heat treatment step of heat treating a die material coated with a Co—Cr alloy in a vacuum furnace at 800 ° C. to 1100 ° C. for 30 minutes to 10 hours. Manufacturing method of die casting mold. 8. The method for producing a die-casting mold according to claim 6, further comprising a blasting step of making the center line average roughness of the surface of the mold material 5 μm to 20 μm. 9. The method for producing a die cast mold according to claim 6, wherein the surface of the mold material is sprayed with Co—Cr alloy powder while cooling the surface of the mold material to 200 ° C. or lower. .