JP3992251B2 - Master alloy for adjusting the magnesium content used during recasting of zinc alloys - Google Patents

Description

【００１８】
第１表中の実施例１〜７のデータから明らかなように、亜鉛合金の鋳返し時に本発明の母合金を使用した場合には、従来の操業条件下の亜鉛合金溶湯温度で短時間に溶解が可能であり、全亜鉛合金溶湯量の増加を１０重量％以内に押さえながらマグネシウムの添加を可能とし、高品質の亜鉛合金への再生を可能とした。しかし、比較例１のデータから明らかなようにマグネシウム含量が８０重量％をこえた母合金を用いた場合には、母合金の表面の酸化が激しく目標値との乖離が大きくなった。また比較例２〜４のデータから、マグネシウム含量が１０重量％より少ない母合金を用いた場合、アルミニウム含量が１０重量％を超えた母合金を用いた場合、または銅含量が５重量％をこえた母合金を用いた場合には、母合金の必要添加量が増加したり融点が高くなるため、母合金を溶湯に添加してから母合金が完全に溶解し適正な溶湯温度になるまで時間がかかり、その間のタイムロスはコストアップの要因となるとともに全亜鉛合金量が増加するなどコスト高の要因となり、またアルミニウム含量が１０重量％を超えた母合金を用いた場合には溶湯中のアルミニウム含量がスペックオーバーした。
【００１９】
【発明の効果】
本発明の母合金は、亜鉛合金の鋳返し時に用いる場合に、従来の操業条件下の亜鉛合金溶湯温度で溶解が可能であり、全亜鉛合金溶湯の増加を１０重量％以内に押さえ、高品質の亜鉛合金への再生を可能とする。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnesium alloy for adjusting the magnesium content used during recasting of a zinc alloy. More specifically, the present invention relates to a case where a zinc alloy mold for press molding, plastic molding, etc. is recast and recycled, or a zinc alloy. When casting die cast products or zinc alloy processed products (plates, wires, extruded products, etc.) and remanufacturing them, or when refining zinc alloy ingots to change the magnesium content in zinc alloy ingots The present invention relates to a magnesium content adjusting master alloy which is added to adjust the magnesium content in the zinc alloy during turning.
[0002]
[Prior art]
When used in the manufacture of molds, zinc alloys have a lower melting point than iron alloys and have good melt flow characteristics, making casting easier, and having a balanced mechanical strength. Good processability, short delivery time, and unnecessary features such as low cost because molds that are no longer needed can be recast and used for press molding for trial production or low-volume production Many are conventionally used as a metal mold or a plastic mold. Further, since the zinc alloy has the above-described characteristics, it is used as a zinc alloy for die casting in automobile parts, home appliance parts, and other various fields. Usually, the zinc alloy used in them is an alloy containing 3% to 7% by weight of aluminum, or an alloy containing 3% to 7% by weight of aluminum and 4% by weight or less of copper. In order to suppress, what was made into the content of 0.05 weight% or less is used.
[0003]
However, when a conventional zinc alloy is used as, for example, a press molding die, it is said that the wear resistance of the die is insufficient depending on the processing conditions such as the material, thickness, and processing shape of the workpiece material to be processed. Also, plastic molds are said to have frequent pinholes and lack of wear resistance, and die cast parts are said to have insufficient creep characteristics. Recently, in addition to aluminum and copper, a zinc alloy that has been added 1-3% by weight of magnesium, which has not been added as an alloy component, has been improved to improve wear resistance, castability and creep resistance. It has come to be used as a property mold or die-cast product.
[0004]
Rather than newly preparing such a magnesium-containing zinc alloy, a zinc alloy having a magnesium content of 0.05% by weight or less is cast back under operating conditions, and then magnesium is added to the magnesium content. If it can be adjusted and used as a magnesium-added zinc alloy, the cost reduction effect is very large. Regarding the method of adding magnesium, magnesium metal can be used as a magnesium raw material when a magnesium-containing zinc alloy is newly melted.
[0005]
[Problems to be solved by the invention]
However, in an attempt to add magnesium metal during recasting of a zinc alloy having a magnesium content of 0.05% by weight or less, the molten metal temperature under operating conditions is 430 ° C. to 450 ° C. The melting point is 200-220 ° C. lower than the melting point of 650 ° C., and the specific gravity of magnesium metal is 1.74, whereas the specific gravity of molten zinc alloy is 6.7 for casting alloys and die casting alloys, for example. As a result, magnesium metal floats on the surface of the molten metal, so the magnesium metal is melted while being submerged in the molten metal. Also, it takes time until the metal is melted, and the magnesium surface is heavily oxidized. It becomes difficult to adjust the composition to the target value.
[0006]
The object of the present invention is to provide a means for easily and simply adding magnesium without causing the above-mentioned problems when adding magnesium during recasting of a zinc alloy, that is, under conventional operating conditions. An object of the present invention is to provide a master alloy for adjusting the magnesium content, which can be easily melted at a molten zinc temperature and enables the preparation of a higher quality magnesium-added zinc alloy.
[0007]
[Means for Solving the Problems]
As a result of intensive studies on the above problems, the present inventors have found that the above problems can be achieved by using a zinc alloy containing a specific amount of magnesium as a master alloy for adjusting the magnesium content, thereby completing the present invention.
[0008]
That is, the magnesium content adjusting master alloy according to the present invention contains 20 to 80% by weight of magnesium, or further contains one or both of aluminum of 10% by weight or less and copper of 5% by weight or less, with the remainder excluding inevitable impurities. It is a mother alloy for adjusting the magnesium content used during recasting of a zinc alloy.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The magnesium content adjusting master alloy of the present invention (hereinafter simply referred to as the master alloy) is used by adding to the zinc alloy molten metal. This zinc alloy molten metal is used for used press molding and plastic molding. Zinc alloy molds, etc., used zinc alloy die-cast products, zinc alloy processed products (plate materials, wire rods, extruded products, etc.), zinc alloy scraps, etc., which are melted for recycling, or unused The zinc alloy ingot may be dissolved in order to change the magnesium content. However, the mother alloy of the present invention can be particularly suitably used for recycling used zinc alloy molds.
[0010]
In the master alloy of the present invention, the magnesium content is preferably limited to 20 to 80% by weight. When a master alloy having a magnesium content of less than 20% by weight is used, the required amount of the master alloy is increased. As a result, after the master alloy is added to the molten metal, the master alloy is completely dissolved and is appropriate. It takes time to reach the molten metal temperature, and the time loss during that time becomes a cause of cost increase. In addition, when the mother alloy of the present invention is used for the re-preparation of a zinc alloy mold, the total weight of the zinc alloy mold increases. For example, if a zinc alloy with a magnesium content of 2% by weight is prepared using a master alloy with a magnesium content of 10% by weight, the total mold weight will increase by 20% by weight, resulting in an increase in inventory and a high cost. become.
[0011]
On the other hand, if the magnesium content exceeds 80% by weight, the melting point of the master alloy exceeds 570 ° C. When a master alloy having such a high melting point is used, at a molten zinc temperature of 430 ° C. to 450 ° C. used in normal operation, the master alloy is completely melted after the master alloy is added to the melt, so that the proper melt temperature is obtained. It takes a long time to complete, and the time loss during that time increases the cost and the master alloy oxidizes, so that a predetermined amount of magnesium cannot be added. As a method of shortening the melting time, it is conceivable to raise the molten metal temperature. However, if the molten metal temperature is raised above 450 ° C., the oxidation of magnesium proceeds and the melting pot is eroded. Is not preferred. In order to melt at a molten metal temperature of 430 ° C. to 450 ° C., it is necessary to use a master alloy having a magnesium content of 80% by weight or less. Accordingly, the magnesium content of the master alloy is 20 to 80% by weight, preferably 30 to 50% by weight.
[0012]
When a zinc alloy containing aluminum is cast back, the amount of aluminum in the molten metal is reduced because noro containing aluminum slightly larger than the aluminum content in the molten metal is generated and the aluminum is removed. Therefore, in order to adjust the aluminum content in the molten metal using only the master alloy, the master alloy needs to contain a larger amount of aluminum than the aluminum content of the zinc alloy before re-casting. However, if the aluminum content in the master alloy exceeds 10% by weight, the aluminum content in the molten metal after the master alloy is added to the required amount of magnesium may exceed the spec, and the melt composition may be adjusted. It becomes difficult. In addition, it takes time until the master alloy is completely melted and reaches an appropriate melt temperature after the master alloy is added to the melt. Therefore, the aluminum content of the master alloy used at the time of recasting the zinc alloy containing aluminum is 10% by weight or less, preferably 4 to 7% by weight. However, it is not always necessary that the mother alloy used for recasting the zinc alloy containing aluminum contains aluminum, but the aluminum content in the molten metal after the addition of the mother alloy not containing aluminum is analyzed, and the required amount of aluminum May be added by a separately prepared master alloy for adjusting the aluminum content.
[0013]
There is little change in the composition of copper due to recasting of the zinc alloy. Therefore, it is sufficient that the mother alloy used for recasting the zinc alloy containing copper contains approximately the same amount of copper as the zinc alloy before recasting. The copper content of the zinc alloy is, for example, 0.03% by weight or less for two types of zinc alloy ingots according to JIS H 2201, and 2 to 4% by weight for general casting zinc alloys. If the copper content exceeds 5% by weight, the melting point of the master alloy becomes 580 ° C or higher, and the zinc alloy melt temperature used in normal operation is 430 ° C to 450 ° C. It takes time until it melts into an appropriate molten metal temperature, and the time loss during that time increases the cost, becomes impractical and produces ε and τ compounds, causing segregation. Therefore, the content of copper in the master alloy used for recasting a zinc alloy containing copper is 5% by weight or less, preferably 4% by weight or less.
[0014]
As is clear from the above explanation, the composition of the master alloy of the present invention used at the time of recasting the zinc alloy is the difference between the composition of the zinc alloy to be recast and the target magnesium-containing zinc alloy composition and the amount of molten metal. The optimum composition may be selected within the range of 20 to 80% by weight of magnesium, 0 to 10% by weight of aluminum and 0 to 5% by weight of copper.
[0015]
In addition, the addition of the mother alloy used at the time of recasting the zinc alloy is performed as follows. Multiple master alloys with different contents and contents (for example, those that do not contain aluminum and copper, those that contain one or both of aluminum and copper, those that have a high magnesium content, those that are medium, and those that have a low content) ) Is prepared. First, the composition of the zinc alloy to be cast is analyzed and used as a basis for calculating the amount of added master alloy. About the aluminum content, the value after readjustment is adopted when readjusting as follows. In addition, the final target composition after adding the master alloy is determined. Thereafter, the paste is removed cleanly under the same conditions as the conventional operating conditions, and if necessary, the aluminum content of the molten zinc alloy is determined according to the pre-reactor analysis method of zinc alloy as described in, for example, JP-A-5-332961. Analyze immediately before and readjust the deficient aluminum by adding the master alloy for adjusting the aluminum content. Next, the master alloy to be used is selected based on the difference in composition between the final target composition and the composition of the zinc alloy to be cast, and the difference in composition between the final target composition and the composition of the zinc alloy to be cast back. And the addition ratio of the mother alloy to be used is calculated based on the amount of molten zinc alloy to be cast. This calculated amount of the master alloy is added to the molten zinc alloy to be cast.
[0016]
【Example】
Below, this invention is demonstrated based on an Example and a comparative example.
Examples 1-7 and Comparative Examples 1-4
As the zinc alloy to be adjusted by reworking, an unused zinc alloy ingot (described as an alloy in Table 1), a used zinc alloy mold for press forming (described as a mold in Table 1) And a used zinc alloy die-cast product (shown as DC material in Table 1). Each zinc alloy was dissolved and their composition was analyzed. The results are as shown in Table 1. The analytical values of magnesium content were 0.03 to 0.04% by weight. From the pre-prepared master alloys of various compositions, the magnesium content in the zinc alloy after addition of the master alloy is about 2% by weight, and the aluminum content and the copper content are almost the same as those in the zinc alloy before recasting. A mother alloy that can be used was selected. The molten metal temperature of each zinc alloy is controlled at 430 ° C., and a selected amount of a mother alloy having the composition shown in Table 1 is added to the molten metal, and stirred until the mother alloy is completely melted to an appropriate molten metal temperature. The time to become was measured. The alloy composition of the melt after adding the mother alloy was analyzed and compared with the target value. The measured values and analytical values were as shown in Table 1.
[0017]
[Table 1]

[0018]
As is apparent from the data of Examples 1 to 7 in Table 1, when the mother alloy of the present invention is used during recasting of the zinc alloy, it takes a short time at the molten zinc temperature under the conventional operating conditions. Melting was possible, and magnesium could be added while suppressing the increase in the total amount of molten zinc alloy within 10% by weight, and regeneration into a high-quality zinc alloy was possible. However, as is clear from the data of Comparative Example 1, when the mother alloy having a magnesium content exceeding 80% by weight was used, the surface of the mother alloy was oxidized strongly and the deviation from the target value was large. In addition, from the data of Comparative Examples 2 to 4, when a master alloy having a magnesium content of less than 10% by weight is used, a master alloy having an aluminum content exceeding 10% by weight, or a copper content exceeding 5% by weight. When the master alloy is used, the required amount of the master alloy increases and the melting point increases, so it takes time for the master alloy to completely melt and reach an appropriate melt temperature after the master alloy is added to the melt. The time loss during this period increases costs and increases the total amount of zinc alloy. In addition, when a master alloy with an aluminum content exceeding 10% by weight is used, aluminum in the molten metal is used. The content was over spec.
[0019]
【The invention's effect】
The master alloy of the present invention can be melted at the molten zinc alloy temperature under the conventional operating conditions when used during recasting of the zinc alloy, and the increase in the total molten zinc alloy is suppressed to within 10% by weight, resulting in high quality. Can be regenerated into zinc alloy.

Claims (5)

A master alloy for adjusting the magnesium content to be used during recasting of a zinc alloy, characterized in that it contains 20 to 80% by weight of magnesium and the balance is made of zinc excluding inevitable impurities. A master alloy for adjusting the magnesium content used for recasting a zinc alloy, comprising 20 to 80% by weight of magnesium and 10% by weight or less of aluminum, the balance being made of zinc except for inevitable impurities. A master alloy for adjusting the magnesium content used for recasting a zinc alloy, comprising 20 to 80% by weight of magnesium and 5% by weight or less of copper, the balance being made of zinc except for inevitable impurities. Magnesium content adjusting mother used at the time of recasting a zinc alloy, characterized in that it contains 20 to 80% by weight of magnesium, 10% by weight or less of aluminum and 5% by weight or less of copper, and the balance is made of zinc except for inevitable impurities. alloy. The mother alloy for adjusting the magnesium content according to any one of claims 1 to 4, which is used at the time of recasting a zinc alloy mold.