JPH0813067A - Metal mold material for shell core - Google Patents

Abstract

PURPOSE:To provide a metal mold material for shell core, well balanced among thermal conductivity, electric discharge processability, and weldability. CONSTITUTION:The metal mold for shell core, having a composition consisting of, by weight, 0.3-1.0% silicon, 1.2-4.0% nickel, 0.1-0.4% zirconium, and the balance essentially copper, is prepared. By this method, the shell core molding cycle can be shortened, and the effect of improving productivity can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shell core mold material used in molding a shell core.

[0002]

2. Description of the Related Art Iron-based materials are generally used as a mold material for molding a shell core. However, iron-based materials have low thermal conductivity, and in order to shorten the molding cycle for molding the shell core and improve productivity, materials with high thermal conductivity are desired, and materials with high thermal conductivity are desired. JP-A-6
It is proposed in Japanese Patent Publication No. 1-279649.

[0003]

The above-mentioned iron-based materials of the prior art have a small thermal conductivity, and it takes time to heat and cool the mold, which is an obstacle to shortening the molding cycle for molding the shell core. Become. In addition, the mold is likely to be thermally deformed and sand burrs are likely to be generated on the dividing surface, which often requires rework. Therefore, the thermal conductivity is higher than that of the iron-based material, the wear resistance due to hardness is the same as that of the iron-based material, for example, FCD45, the electrical discharge machinability required in the die machining is excellent, and the model change of the die It is desired that overlay welding for the above-mentioned repair can be performed.

The copper-based material proposed in JP-A-61-279649 contains zirconium as an alloy component, and the addition amount of zirconium described in the above-mentioned publication is 0.01 to 3.0 weight. In the range of%, EDM,
Significantly lower weldability than ferrous materials.

On the other hand, recent copper-based materials contain aluminum as an alloy component, and when the amount of aluminum added is in the range of 10 to 13% by weight, the wear resistance is comparable to that of iron-based materials, but the heat resistance is high. The conductivity is only slightly better than iron-based materials.

As described above, the prior art cannot be said to have a good balance of thermal conductivity, electric discharge machinability and weldability, and has a problem as a mold material for a shell core.

The objects of the present invention are thermal conductivity, electric discharge machinability,
It is intended to provide a mold material for a shell core having a good weldability.

[0008]

Means for Solving the Problems The above-mentioned objects are as follows: 0.3 to 1.0% by weight of silicon, 1.2 to 4.0% by weight of nickel,
Achieved by containing 0.1 to 0.4% by weight of zirconium, the balance consisting essentially of copper.

The above objects are as follows: 0.3 to 1.0% by weight of silicon, 1.2 to 4.0% by weight of nickel, 0.1 to 0.4% by weight of zirconium, and 0.3% by weight of aluminum. It is achieved by containing the following and making the balance substantially copper.

[0010]

[Function] Conventional copper-based materials have high thermal conductivity,
EDM and weldability are poor.

However, in the alloy having the above-mentioned structure, nickel and silicon precipitate intermetallic compounds such as Ni ₂ Si to improve the electrical discharge machinability and weldability without lowering the thermal conductivity so much and to improve wear resistance. I am raising.

To improve these characteristics, it is most effective to set the compounding ratio of nickel and silicon to about 4: 1 by weight, but since it is strengthened by adding aluminum, the silicon / nickel ratio is increased. 0.225 to 0.245
Is preferred.

The amount of nickel is required to be 1.2% by weight from the viewpoint of wear resistance and thermal conductivity, and these properties improve with the addition amount, but addition of a large amount impairs hot workability and weldability. However, the upper limit is 4.0% by weight, because the improvement of the thermal conductivity beyond a certain amount is not recognized. In particular, 2.0 to 3.5% by weight is preferable.

As described above, silicon is an essential element for improving wear resistance and thermal conductivity, and is about 4 times as much as nickel.
Since one-third is appropriate, it was set to 0.3 to 1.0% by weight. Particularly, 0.45 to 0.85% by weight is preferable.

The amount of zirconium is 0.1 from the viewpoint of wear resistance.
The upper limit is 0.4% by weight because the weight% is necessary, and if it exceeds a certain amount, the thermal conductivity is impaired. In particular, 0.15 to 0.35% by weight is preferable.

The amount of aluminum enhances the wear resistance, but if it exceeds a certain amount, it impairs the thermal conductivity, so its upper limit is 0.3% by weight. 0.01 to 0.25% by weight
Is preferred.

The material of the present invention may be either one that is cast, one that is hot-worked after casting, and one that has been subjected to a heat treatment at 900 to 950 ° C and then an aging treatment at 430 to 500 ° C.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

Table 1 shows an example of alloy composition, mechanical properties and thermal conductivity of this example.

[0020]

[Table 1]

The alloys of the present invention shown in Table 1 have No. The silicon / nickel ratio of No. 1 is 0.242, No. 1 No. 2 has a silicon / nickel ratio of 0.232. The silicon / nickel ratio for 3 is ~ 0.236.

Next, the alloy manufacturing method of this embodiment will be described.

Taking the alloy No. 3 shown in Table 1 as an example of the melting procedure, first, copper is melted and then nickel and silicon are added,
Then, nitrogen gas was blown into the molten metal for bubbling to perform degassing, and finally zirconium was added to form a uniform molten metal, which was cast into a sand mold formed in advance and solidified. The casting temperature was 1200 ° C., the melting furnace was an Elema furnace, and the crucible was graphite. The size of the ingot is 50m in diameter
m × length 200 mm and weight was about 3 kg.

The alloy of this embodiment is basically a copper-zirconium alloy in which Ni ₂ Si intermetallic compound is dispersed uniformly and finely. This shows a satisfactory value of 0.393 cal / sec · cm ° C. even with respect to the thermal conductivity required for the shell core mold material. Further, at a shell firing temperature of around 350 ° C., the dispersed Ni ₂ Si intermetallic compound having high hardness functions to have wear resistance almost equal to that of the iron-based material FCD45.

Next, the evaluation method of this embodiment will be described.

Abrasion resistance A test piece was sampled from the ingot obtained by the above-mentioned manufacturing method, and sand abrasion resistance was evaluated. The evaluation method was as follows: a test piece was added to a solution prepared by mixing 5% by weight of silica sand (Jingu sand No. 6) with water,
Abrasion rate was used to evaluate the weight loss when rotating at a speed of / sec.

FIG. 1 is a table comparing the wear resistance of the alloy of the example of the present invention and the conventional alloy. Alloy No. 2 in Table 1
The material of this example represented by the formula (1) has a smaller wear rate than conventional FC25 and zirconium copper, and is excellent in sand wear resistance.

Electrical Discharge Machining Performance comparison was performed when various copper alloys and S45C were subjected to electrical discharge machining using a copper electrode.

FIG. 2 is a chart comparing the electric discharge machinability of the alloy of the example of the present invention and the conventional alloy.

This figure shows the alloy No. 2 of Table 1 in the electric discharge machinability.
It is a comparison of the processing speed of.

FIG. 3 is a table comparing the electric discharge machinability of the alloy of the example of the present invention and the conventional alloy.

This figure shows the alloy No. 2 of Table 1 in the electric discharge machinability.
It is a comparison of the electrode wear rate when processing the.

The material of this example, which is represented by alloy No. 2 in Table 1, has improved electrode wear rate and processing speed as compared with the conventional zirconium-copper alloy.

Life and Productivity A mold for a shell core having a thickness of 150 mm, a width of 250 mm and a length of 450 mm is manufactured, and 8,000 shots have been used so far. To be done. In addition, the shot time is shortened from 2.4 minutes to 1.5 minutes, improving productivity.

[0035]

According to the present invention, by precipitating an intermetallic compound such as Ni ₂ Si on a zirconium-copper alloy, heat conductivity, electric discharge machinability and weldability are balanced, and a shell core forming cycle is achieved. The effect of shortening and improving productivity can be obtained.

[Brief description of drawings]

FIG. 1 is a chart comparing the wear resistance of an alloy of an example of the present invention and a conventional alloy.

FIG. 2 is a chart comparing the electric discharge machinability of the alloy of the example of the present invention and the conventional alloy.

FIG. 3 is a chart comparing the electric discharge machinability of the alloy of the example of the present invention and the conventional alloy.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Baba 7-1-1, Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory

Claims (2)

[Claims] 1. 0.3 to 1.0% by weight of silicon, 1.2 to 4.0% by weight of nickel, and 0.1 to 0.4% of zirconium.
A mold material for a shell core, characterized in that it is contained by weight, and the balance is substantially composed of copper. 2. Silicon in an amount of 0.3 to 1.0% by weight, nickel in an amount of 1.2 to 4.0% by weight, and zirconium in an amount of 0.1 to 0.4% by weight.
A metal mold material for a shell core, characterized in that the content of aluminum is 0.3% by weight or less and the balance is substantially copper.