JPH1036926A - Master alloy for composition regulation, for use in recasting of zinc alloy metal mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and simply repeat recasting of a metal mold by specifying Al content in a master alloy for composition regulation. SOLUTION: In this master alloy, it is preferable to limit Al content to 20-50% by weight. When used zinc alloy metal mold is recast, usually slag is formed by 3-5wt.%. In this case, when a master alloy of <20% Al content is used, the amount of an alloy to be added becomes inevitably larger than the amount of the slag formed and costs are increased. Further, when Al content exceeds 50%, the melting point of the master alloy becomes >=560 deg.C. Accordingly, at a molten alloy temp. of 430-450 deg.C used at the ordinary operation, the master alloy of >50% Al content is of no practical use because the length of time from the addition of the master alloy to the molten alloy to melting is extended. It is undesirable to raise the molten alloy temp. to >450 deg.C for the purpose of shortening the melting time, because a melting pot is attacked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition adjusting master alloy used for recasting a zinc alloy mold, and more particularly, to recast a zinc alloy mold for press molding or a zinc alloy mold for plastic molding. The present invention relates to a composition adjusting master alloy added to adjust the alloy composition when the alloy is reused.

[0002]

2. Description of the Related Art Zinc alloys have a lower melting point than iron alloys and have good melt flowability, so that they are easy to cast. In addition, they have well-balanced mechanical strength, good workability, and short workability. Due to the fact that the delivery time is possible and the unnecessary mold can be cast back and used, it is low cost, etc., so it is a press molding mold or plastic molding mold for trial operation or small quantity production. Many types have been used in the past.

[0003] However, when recast, the aluminum component in the alloy is oxidized or iron eluted from the iron-based component contained in the mold reacts with aluminum in the alloy to form an Al-Fe compound. However, the effective aluminum content in the molten zinc alloy decreases due to dross formation, and the reduction of the effective aluminum content exceeds an allowable range when casting is repeated. Further, the magnesium content and the copper content in the zinc alloy also slightly fluctuate due to casting, similarly to the aluminum content.

[0004]

When such recasting is repeatedly performed, the zinc alloy composition fluctuates to deteriorate the castability, the number of pinholes affects the mold surface quality, Actual operation is hindered due to a decrease in strength, etc. Conventionally, quality preservation technology has been established for molds with significantly reduced castability due to repeated casting and molds with reduced strength. Because it was not done, the waste was disposed of by a waste disposal company. Therefore, there has been a demand for measures to establish a quality preserving technique for preserving the quality of a die produced by casting.

An object of the present invention is to provide a means for easily and easily repeatedly casting a zinc alloy mold without the problems described above, that is, a conventional method of melting a zinc alloy under operating conditions. Melting is possible at a temperature, the composition of the molten metal can be controlled without increasing the total amount of the zinc alloy molten metal, and the quality of the metal mold can be prevented from being deteriorated by recasting. It is an object of the present invention to provide a composition adjusting master alloy used when recasting a zinc alloy mold.

[0006]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a zinc alloy containing 20 to 50% by weight of aluminum is used as a composition adjusting master alloy to achieve the above object. Have been achieved, and the present invention has been completed. That is, the composition adjusting master alloy of the present invention contains 20 to 50% by weight of aluminum, 0 to 10% by weight of copper, and 0 to 5% by weight of magnesium, and the balance is made of zinc excluding unavoidable impurities. This is a composition-adjusting master alloy used when casting a zinc alloy mold.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the composition adjusting master alloy of the present invention, the aluminum content is preferably limited to 20 to 50% by weight. When a used zinc alloy mold is cast, slag is usually generated in an amount of 3 to 5% by weight. When a composition adjusting master alloy having an aluminum content of less than 20% by weight is used at the time of recasting, the amount of the composition adjusting mother alloy to be added is inevitably larger than the amount of the formed slag. Total weight increases. As a result, the stock amount increases and the cost increases.

If the aluminum content exceeds 50% by weight, the melting point of the composition-adjusting master alloy will exceed 560 ° C. With such a composition adjusting master alloy having a high melting point, the zinc alloy melt temperature 430 to 430 used in normal operation is used.
At 450 ° C., the time from the addition of the composition-adjusting master alloy to the molten metal until the melting thereof becomes long, which is not practical. Since the time loss at the casting site directly leads to an increase in cost, the time required for melting the composition adjusting master alloy is at most 15
Minutes are the limit. As a method of shortening the melting time, it is conceivable to raise the temperature of the molten metal.
If the temperature is higher than 50 ° C, the melting pot will be eroded.
Operation at a melt temperature above 0 ° C. is not preferred. 450
In order to melt at a temperature of the molten metal of about 15 ° C. in about 15 minutes, it is necessary to use a composition adjusting master alloy having an aluminum content of 50% by weight or less. Therefore, the aluminum content of the composition-adjusting master alloy is preferably 20 to 50% by weight, and more preferably 25 to 35% by weight.

The change in the composition of copper due to the recast of the zinc alloy mold is smaller than the change in the composition of aluminum. Therefore, it is not necessary that all the composition adjusting master alloys used at the time of recasting of the zinc alloy mold contain copper. It is also possible to repeat the order of addition by adding a copper-free composition-adjusting master alloy containing no copper the fourth time. Even when using a composition adjusting master alloy containing copper, the addition amount of the composition adjusting master alloy is determined by the required amount of aluminum. In order to determine, it is preferable to make the copper content in the composition adjusting master alloy containing copper relatively small. When the copper content exceeds 10% by weight, the melting point of the alloy becomes 580 ° C. or higher, and when a composition adjusting master alloy having such a high melting point is used, at a zinc alloy molten metal temperature of 430 to 450 ° C. used in a normal operation, The time from the addition of the composition-adjusting master alloy to the molten metal until the melting thereof becomes longer, which is not practical and generates ε compounds and τ compounds, which causes segregation. Therefore, the copper content of the composition adjustment master alloy is set to 1
0% by weight or less, preferably 5% by weight or less.

[0010] Magnesium in the zinc alloy for a mold must be present in an amount of 0.03 to 0.06% by weight in order to eliminate intergranular corrosion due to impurities such as lead, cadmium and tin. The change in the composition of magnesium due to the recast of the zinc alloy mold is smaller than the change in the composition of aluminum. Therefore, not all the composition adjusting master alloys used in recasting the zinc alloy mold need necessarily contain magnesium. It is also possible to repeat the addition sequence by adding the magnesium-free composition-adjusting master alloy containing no magnesium for the third time.
Even when using a composition-adjusting master alloy containing magnesium, the addition amount of the composition-adjusting master alloy is determined by the required amount of aluminum. In order to determine, it is preferable to make the content of magnesium in the composition adjusting master alloy containing magnesium relatively small. When the magnesium content in the composition adjustment master alloy exceeds 5% by weight,
A magnesium-zinc compound is formed, which may cause segregation and may make the material brittle, so that it is not preferable that the magnesium content exceeds 5% by weight. Therefore, the magnesium content is set to 5% by weight or less, preferably 1% by weight or less.

As is apparent from the above description, the composition of the composition-adjusting master alloy of the present invention to be used at the time of recasting a zinc alloy die depends on the alloy composition of the die to be recast and the target die. The optimum composition may be selected within the range of 20 to 50% by weight of aluminum, 0 to 10% by weight of copper, and 0 to 5% by weight of magnesium according to the difference from the alloy composition and the amount of molten metal.

The addition of a composition-adjusting master alloy used when recasting a zinc alloy mold is performed as follows. First, the slag is cleanly removed under the same conditions as the conventional operating conditions, and then the zinc alloy composition of the molten metal is described, for example, in JP-A-5-332960 and JP-A-5-332196. Analysis immediately before the furnace in accordance with the pre-furnace analysis method for various zinc alloys. From the analyzed zinc alloy molten metal composition, composition-adjusting mother alloy composition and molten metal amount,
The amount of the composition-adjusting master alloy is calculated and added so as to match the target zinc alloy composition for the mold.

As is apparent from the above description, the use of the composition-adjusting master alloy of the present invention makes it possible to maintain a molten zinc alloy that has deviated from the original zinc alloy composition to the original zinc alloy composition. In addition, it is possible to prevent the characteristics of the zinc alloy mold from being deteriorated due to the recasting, or to recover the characteristics of the zinc alloy mold that has been deteriorated by the recasting.

[0014]

【Example】

Examples 1 to 7 and Comparative Examples 1 and 2 Used zinc alloy molds were put in a melting pot and melted, and the generated slag was completely removed. The weight of the removed slag was evaluated, and the alloy composition of the molten metal was analyzed. From the alloy composition of the molten metal, the composition of the mother alloy for composition adjustment, and the amount of the molten metal, the target zinc alloy composition for the mold (Zn-3.8 to 4.5% by weight Al
-2.5 to 3.5 wt% Cu-0.02 to 0.04 wt% Mg), the amount of the composition-adjusting mother alloy was calculated. The target mold composition this time was Zn-4.2.
Wt% Al-3 wt% Cu-0.04 wt% Mg. While controlling the temperature of the molten metal at 430 to 440 ° C., the composition-adjusting mother alloy was added to the molten metal, and the time required for complete stirring and melting was measured. The alloy composition of the molten metal after the addition of the composition-adjusting mother alloy was analyzed and compared with a target value. This operation was performed 9 times (Examples 1 to 7 and Comparative Examples 1 and 2). The measured values, analytical values, and calculated values are as shown in Table 1.

[0015]

[Table 1]

As is apparent from the data of Examples 1 to 7 in Table 1, the use of the composition-adjusting master alloy of the present invention, which is used at the time of recasting a zinc alloy mold, makes it possible to obtain zinc under conventional operating conditions. Melting is possible at the temperature of the molten alloy, and the composition of the molten metal can be controlled without increasing the total amount of the molten zinc alloy. Production becomes possible. However, as is clear from the data of Comparative Example 1, when the aluminum content in the composition-adjusting master alloy is 60% by weight, which is more than 50.0% by weight, the melting point of the composition-adjusting master alloy is 590 ° C. Therefore, the time from the addition of the composition-adjusting master alloy to the molten metal to the melting thereof is 30 minutes, which is not practical. Further, as is apparent from the data of Comparative Example 2, when the aluminum content in the composition-adjusting master alloy is 10.0% by weight, which is less than 20% by weight, the necessary addition amount of the composition-adjusting master alloy is required. Becomes 320 Kg, and the amount of the composition-adjusting mother alloy to be added becomes larger than the amount of the formed slag, the total weight of the mold increases, and as a result, the stock amount increases and the cost increases.

[0017]

The use of the composition-adjusting master alloy of the present invention makes it possible to easily and easily repeat the casting of a zinc alloy mold, and to melt at the temperature of the zinc alloy melt under the conventional operating conditions. It is possible to control the composition of the molten metal without increasing the total amount of the molten zinc alloy, to prevent the quality of the die from being deteriorated by casting, and to manufacture a less expensive zinc alloy die.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Oshiro 1333-2, Hara-shi, Ageo-shi, Saitama Mitsui Mining & Smelting Co., Ltd. (72) Inventor Fuminori Matsuda 1 Toyota Town, Toyota-shi, Aichi Prefecture Toyota Motor Corporation Inside

Claims (4)

[Claims] 1. A composition-adjusting mother alloy for use in recasting a zinc alloy mold, characterized by containing 20 to 50% by weight of aluminum and the balance being made of zinc excluding unavoidable impurities. 2. 20 to 50% by weight of aluminum and 10% by weight of copper
A composition adjusting master alloy for use in recasting a zinc alloy mold, characterized in that it contains zinc by weight, with the exception being in weight percent, with the balance being zinc excluding unavoidable impurities. 3. A composition adjusting base for use in recasting a zinc alloy mold, characterized in that it contains 20 to 50% by weight of aluminum and 5% by weight or less of magnesium, and the balance is made of zinc excluding unavoidable impurities. alloy. 4. The composition according to claim 1, wherein the composition contains 20 to 50% by weight of aluminum, 10% by weight or less of copper and 5% by weight or less of magnesium, and the balance is made of zinc excluding inevitable impurities.
Composition adjusting mother alloy used when casting zinc alloy molds.