JPH0320427A - Alloy for high strength die - Google Patents

Abstract

PURPOSE:To obtain the alloy for a high strength die having excellent mechanical strength, easy to cast and furthermore having excellent weldability by specifying the compsn. constituted of Zn, Mn, Fe, Al, Ni, Co and Cu with inevitable impurities. CONSTITUTION:The alloy for a high strength die is formed from, by weight, <=2% Zn, 0.5 to 3% Mn, 0.5 to 3% Fe, 0.5 to 15% Al, 0.01 to 2% Ni and/or Co and the balance Cu with <=0.5% inevitable impurities, which has excellent mechanical strength, has high surface hardness, has good castability and furthermore has excellent weldability. Since the alloy has relatively low m.p. of about 1000 deg.C, casting is easily executed to manufacture a high strength die in a short time. The alloy moreover has high content of Cu having high heat conductivity and is therefore suitable particularly to a structural material such as a die for plastic molding.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a high-strength mold alloy suitable for use as a structural material for plastic molds and the like. [Prior Art] In recent years, the housings, components, etc. of office equipment and other types of equipment have been made of plastic, and these equipments have undergone frequent model changes in order to improve their performance. Along with this, the molding cycle for plastic molded products has become shorter, and high-mix, low-volume production is being implemented. For this reason, casting/
There is a need for materials that are easy to process. Metals such as cast iron and cast steel are used as constituent materials for conventional plastic molds, especially injection molds. Although these metals have excellent mechanical strength, they cannot be cast or
Difficult to process. That is, since cast iron and cast steel have high casting temperatures, they require large-scale casting equipment. Also, simple casting is done in a sand mold, but in that case the casting temperature is about 1
Since the temperature is as high as 500°C, the surface of the cast product becomes rough, and therefore, a large number of man-hours are required for surface polishing. In addition, in order to manufacture precision molds, a large amount of time is required for machining such as cutting and electrical discharge machining. Therefore, in recent years, zinc-based alloys and copper-based alloys have been used as constituent materials for plastic molds, which have low casting temperatures and are easy to cast/process. Zinc-based alloys are JIS H5
Zinc alloy for die casting specified by 301 (ZDC-1
), and in addition to Zn, it also contains AI2, Cu,
Contains Mg etc. Further, the copper-based alloy contains ^n, Fe%Mn, etc. in addition to Cu, as shown in Japanese Patent Publication No. 56-11380, for example. [Problems to be Solved by the Invention] However, the conventional zinc-based alloys and copper-based alloys described above have insufficient mechanical strength and hardness. That is, when using these alloys as structural materials for plastic molding molds,
There is a risk of cracks occurring on the mold surface. In addition, as this alloy is repeatedly used in certain molding operations, the dimensional accuracy of the mold deteriorates, potentially causing cracks in the plastic molded product.For this reason, this mold can only be used as a prototype mold. . In recent years, duraluminium-based aluminum alloys have been used as mold alloys for high-mix, low-volume production.
Since this aluminum alloy is usually forged, it has fewer defects such as holes inside the material and has a high surface hardness. Since it is an alloy whose main component is aluminum, it has excellent machinability such as cutting speed and electrical discharge machining. However, for welding work such as overlay welding due to minute design changes during mold manufacturing, troubles during cutting, processing errors, or repair of structural defects such as pinholes, welding work and welding There is a large difference in the surface microstructure from the surrounding surface of the work, and this is transferred to the molded product, resulting in serious practical problems such as extremely poor quality of the molded product. An object of the present invention is to provide a high-strength mold alloy that has excellent mechanical strength, is easy to cast/process, and has excellent weldability. [A Thousand Steps to Solve the Problem] The high-strength mold alloy according to the present invention has Z
n 2% or less, Mn 0.5-3%, Fe 0.5-3%
, AI20.5-15%, 0.01-2% Ni or Go or a mixture of both, and the balance Cu and 0.5%
It consists of the following unavoidable impurities. [Function] Since the alloy of the present invention mainly contains Cu and AJ2, it can ensure mechanical strength and have good casting/workability. Also, Mn. Mechanical strength is improved by adding Zn and Fe, and oxidation resistance and toughness are improved by adding Ni. Impurities such as PB have low solubility in Cu,
Since it precipitates into grain boundaries and adversely affects corrosion resistance, it is necessary to keep the concentration as low as possible. The reason why the constituent elements of the alloy are limited as described above will be explained below. ■A2 content AI2 has the effect of improving mechanical strength by alloying with Cu. The effect is that if the content exceeds 15%, the strength increases, and if it is less than 0.5%, the desired strength-improving effect cannot be obtained, so the content was set at 0.5 to 15%. (2) Zn content Zn has the effect of improving machinability, but when the content is excessive, it reduces mechanical strength. The amount required to produce an effect was set at 2% or less. ■Mn content Mn has the effect of improving mechanical strength, but if the content is less than 0.5%, the desired strength improvement effect cannot be achieved, while if the content exceeds 3%, it will become brittle. From doing that,
It was set at 0.5-3%. ■Fe content Fe has the effect of improving mechanical strength and hardness, but it has no effect if the content is less than 0.5%, and it becomes brittle if it is more than 3%, so it was set at 0.5 to 3%. ．． (2) Content of Ni or Go or a mixture of both Ni or Go or a mixture of both has the effect of improving corrosion resistance and hardness, but no effect can be obtained if the content is less than 0.01%. In addition, if the content exceeds 2%,
In order to form arms, the amount was set at 0.01 to 2%. That is, in the alloy of the present invention, by mixing the above-mentioned metal elements in the above-mentioned contents, mechanical strength and surface hardness are increased, #A buildability/workability is improved, and weldability is improved. It is possible to improve the performance.

[Example] Table 1 shows the tensile strength and hardness of the alloy of the present invention in comparison with a comparative alloy. Cu-Zn-AI2-Fe-Mn- with the composition shown in Table 1
After creating Ni (Col-based alloys A-G of the present invention) and confirming that each component was uniformly dissolved, JIS H 530
1. A tensile test piece shown in Reference Figure A was prepared. These tensile test pieces were subjected to a tensile test according to JIS Z 2241, and their tensile strength at break was determined. In addition, the Brinell hardness of each of the above alloys was measured according to JIS Z 2243. The results are shown in Table 1. In addition, when welded the alloys of the present invention shown in Table 1 using common materials, polished the welded parts, and inspected the surface properties, no problems were found in any of them. In addition, comparative alloy H-L shown in Table 1
The tensile strength and hardness were also measured using the same method as above. Comparative alloy J is a zinc alloy for casting molds (ZAS) manufactured by Mitsui Mining and Mining ■, and comparative alloy K is JIS l{
The brass casting (YBsC1) specified by 5101 and the aluminum alloy specified by JIS 7075 are used for comparison. The weldability of these comparative alloys was also tested in the same way as mentioned above, and there were almost no problems with the exception of the AI2 series alloy (7075 alloy) specified by JIS H4140. According to Table 1, it is recognized that the alloy of the present invention is superior in tensile strength and hardness compared to the comparative alloy. In addition, the alloy of the present invention has a relatively low melting point of approximately 1000°C compared to cast iron and cast steel, and has good casting/processability. Therefore, high-strength molds can be manufactured in a relatively short time, and injection molding is possible. It is recognized that it is very useful as an alloy for forming molds, etc. Furthermore, as is clear from its composition, the alloy of the present invention has a large content of Cu, which has a high thermal conductivity, and therefore has the advantage that it requires less time for heating and cooling.
This means that when used as a mold for injection molding of plastics, the molding time is short, making it extremely useful as an alloy for injection molding. [Effect of the invention】

Claims (1)

[Claims] (1) Zn 2% or less, Mn 0.5 to 3 in weight percent
%, Fe0.5-3%, Al0.5-15%, 0.01
A high-strength mold alloy comprising ~2% of Ni or Co, or a mixture of both, the balance being Cu and 0.5% or less of unavoidable impurities.