KR101194218B1 - Lead-free cutting bronze alloy for metal mold casting and the manufacturing method thereof - Google Patents

Abstract

PURPOSE: Lead-free bronze alloy for mold casting and a preparation method thereof are provided to simplify a bronze casting process while minimizing the content of lead and to reduce harmful effect to human bodies by employing bismuth or selenium instead of lead. CONSTITUTION: Lead-free bronze alloy for mold casting comprises Pb of 0.1wt.% or less, Zn of 8.0-13.0wt.%, Si of 3.0-6.0wt.%, Sn of 1.50wt.% or less, Ni of 1.0wt.% or less, Bi of 0.7-2.50wt.%, Al of 1.50wt.% or less, Se of 0.30-1.0wt.%, and Cu and inevitable impurities of the remaining amount. [Reference numerals] (AA) Embodiment 1; (BB) Embodiment 2

Description

Lead-free bronze alloy for die casting and its manufacturing method {LEAD-FREE CUTTING BRONZE ALLOY FOR METAL MOLD CASTING AND THE MANUFACTURING METHOD THEREOF}

The present invention relates to a lead-free bronze alloy for die casting, and a method for manufacturing the same. Specifically, in forming a bronze alloy, mold casting using a bronze alloy is possible by adding silicon (Si) instead of tin (Sn). In addition, the present invention relates to a lead-free bronze alloy for die casting, and a method of manufacturing the same, while significantly reducing the content of lead (Pb) by adding bismuth (Bi) or selenium (Se).

Bronze is the alloy that has been used for the longest time among copper (Cu) alloys and mainly refers to an alloy of copper (Cu) and tin (Sn). It is sometimes referred to as bronze that it contains aluminum (Al) or manganese instead of tin (Sn) instead of tin (Sn), but basically bronze refers to an alloy of copper (Cu) and tin (Sn). Such bronze is called tin (Sn) bronze.

Types of tin (Sn) bronzes include money, plaque bronze, gunmetal, bell bronze, craft bronze, mirror bronze, mechanical bronze, special bronze, and generally have high mechanical properties, excellent corrosion resistance, and good castability. It is widely used in various industrial materials.

Mechanical bronze is an alloy of 90% copper and 10% tin, which is used for gun barrels, valves, gears, flanges, pistons and spindles.

Phosphor Bronze has excellent corrosion resistance and abrasion resistance, and has high strength and good bendability. In addition, the electrical thermal conductivity is easy to bond even with lead (Pb) soldering and plating as well as has the advantage of strong chemical corrosion. Examples used are bushings, gears, bolts, nuts, automotive parts, and the like.

Leaded Tin Bronze is suitable for bearings with high surface pressure, good intimacy, and good scoring resistance.

Special bronzes include aluminum (Al) bronze, manganese bronze, silicon bronze, and nickel (Ni) bronze.

These bronzes are composed mainly of tin (Sn), copper (Cu), zinc (Zn), etc., and other small amounts of lead (Pb) and residual components. Tin (Sn) bronze is copper (Cu) as the main component and added tin (Sn) is added to suppress the elution of lead (Pb) by improving the castability and corrosion resistance. Lead (Pb) used here is mainly used to improve the machinability of bronze.

However, as already well known in the art, in order to produce castings using tin bronze, sand-casting is mainly used. This is because tin bronze, which contains a large amount of tin, can not be used for mold casting due to its high solidification rate. However, in the case of sand casting, the working environment is poor and the surface is rough. On the other hand, the product produced by using the mold casting is not only superior in quality than the product of the sand casting, but also simple equipment and excellent working environment has been required to develop a bronze alloy for mold casting.

In addition, in the case of bronze alloy, lead (Pb) is included for machinability, and the hazards of lead (Pb) are widely known as environmental problems or health problems, and the use of lead (Pb) is severely restricted. . For example, in the case of producing and using products such as water pipes using bronze containing lead (Pb), lead (Pb) may be eluted in the water and the human body may have to be considered. .

Therefore, development of bronze which does not use lead (Pb) is required. However, when lead (Pb) is not used in forming bronze, there is a disadvantage in that workability is poor, such as a decrease in machinability. Research is being conducted to improve the machinability without using lead.

According to Korean Patent Registration No. 10-0864909, a free-cutting copper alloy containing calcium (Ca) is provided, which comprises copper (Cu), zinc (Zn), and calcium (Ca) in the bronze alloy. However, copper is 59 to 79% by weight, calcium (Ca) is characterized in that 0.1 to 1.5% by weight, the balance is made of zinc (Zn).

The present invention has been made to solve the conventional problems as described above, in forming the bronze alloy by adding silicon (Si) to replace the tin (Sn) as well as enabling the mold casting using the bronze alloy as well as lead Instead of minimizing the content of the (Pb) component, bismuth (Bi) or selenium (Se) can be used to produce products that are harmless to the human body and provide a lead-free bronze alloy suitable for mold casting with improved cutting processability, and a method of manufacturing the same.

According to an aspect of the present invention,

0.1 wt% or less of lead (Pb), 8.0-13.0 wt% of zinc (Zn), 3.0-6.0 wt% of silicon (Si), 1.50 wt% or less of tin (Sn), 1.0 wt% or less of nickel (Ni), bismuth (Bi) ) 0.7-2.50% by weight, aluminum (Al) 1.50% by weight, selenium (Se) 0.30 ~ 1.0% by weight, the remainder is copper (Cu) and provides an lead-free bronze alloy for die casting, characterized in that unavoidable impurities It is.

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The present invention to achieve the above object,

0.1 wt% or less of lead (Pb), 8.0 to 10.0 wt% of zinc (Zn), 3.0 to 4.0 wt% of silicon (Si), 0.7 to 2.50 wt% of bismuth (Bi), and 1.50 wt% or less of aluminum (Al) , Selenium (Se) 0.30 ~ 1.0% by weight and the remainder is to provide a lead-free bronze alloy for die casting, characterized in that the copper (Cu) and inevitable impurities.

The present invention to achieve the above object,

0.1 wt% or less of lead (Pb), 8.0-10.0 wt% of zinc (Zn), 3.0 to 4.0 wt% of silicon (Si), 1.5 wt% or less of tin (Sn), 1.0 wt% or less of nickel (Ni), Lead-free bronze for casting, characterized in that the bismuth (Bi) 0.7 ~ 2.50% by weight, aluminum (Al) 1.50% by weight, selenium (Se) 0.30 ~ 1.0% by weight, the remainder is copper (Cu) and unavoidable impurities To provide an alloy.

Further, according to the present invention,

Copper (Cu) scrap, zinc (Zn) now, silicon (Si) now, lead (Pb) now, tin (Sn) now, nickel (Ni) now, bismuth (Bi) now, aluminum (Al) now, selenium ( Se) step of formulating now and infiltrating into the electric furnace; Dissolving the temperature in the electric furnace at 1,130 to 1,230 ° C. to obtain a molten alloy; Stirring and degassing the molten alloy; Improving the flowability and tissue of the molten metal and the surface smoothly; Removing the oxide floating in the slag state; It is to provide a method for producing a lead-free bronze alloy for die casting, comprising a; casting the molten alloy from which the slag oxide is removed into ingot.

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The lead-free bronze alloy for die casting according to the present invention is different from the conventional bronze alloy which mainly uses the sand casting method by using silicon (Si), which is easily obtained by replacing tin (Sn), which is a main alloy element, in a conventional lead-free bronze alloy. It is possible to obtain a mold of excellent mold environment and excellent working environment has the advantage of obtaining a good quality product.

In addition, despite the use of almost no lead (Pb), due to its excellent cutting processability, the bronze casting production process can be easily and conveniently improved, and as a result, there is less industrial waste, thereby providing an environmentally friendly casting method. There is this.

Furthermore, the die casting lead-free bronze casting according to the present invention can supply good products such as various valves, water metering devices, faucet fittings, and various fittings related to water to the domestic market at a lower price and open up a new overseas export market. There is an advantage.

1 is a flow chart showing a method of manufacturing a lead-free bronze alloy for die casting according to the present invention,
Figure 2 is a flow chart showing a lead-free bronze mold casting method using a lead-free bronze alloy for die casting according to the present invention,
3 is a photograph of a mold casting of a lead-free bronze alloy for die casting according to the present invention;
Figure 4 is a photograph of a precision mold casting of lead-free bronze alloy for die casting according to the present invention,
Figure 5 is a photograph showing the shape of the cut chip of the mold casting casting of the lead-free bronze alloy for die casting according to Examples 1 and 2 of the present invention.

The present invention is 0.1% by weight or less of lead (Pb), 8.0-13.0% by weight of zinc (Zn), 3.0-6.0% by weight of silicon (Si), 1.50% by weight of tin (Sn), 1.0% by weight or less of nickel (Ni), Lead-free bronze for casting, characterized in that the bismuth (Bi) 0.7 ~ 2.50% by weight, aluminum (Al) 1.50% by weight, selenium (Se) 0.30 ~ 1.0% by weight, the remainder is copper (Cu) and unavoidable impurities It is characterized by providing an alloy.

Lead (Pb) according to the invention is preferably mixed below 0.10% by weight. In general, the machinability of the bronze alloy can be significantly improved by adding lead (Pb). However, lead (Pb) is limited in its use due to its toxicity, especially in the case of water-related products.

Lead (Pb) is the heaviest and most flexible metal among industrial metals. It is rich in malleability and easy to roll into a plate or tube, but it is too flexible to draw. Due to such flexibility, when lead (Pb) is mixed, the cutting processability is excellent, whereas when lead (Pb) is not used, there is a problem that the cutting processability is bad. In the present invention, bismuth (Bi) or selenium (Se) is added as a substitute element in order to reduce the use of lead (Pb) in order to increase the machinability while minimizing the harmfulness of lead (Pb).

Bismuth (Bi) used in the present invention is used 0.7 to 2.50% by weight, selenium (Se) is used 0.3 to 1.0% by weight. When the content of bismuth (Bi) and selenium (Se) used in the present invention is out of the above range, there is a problem that the machinability and mechanical properties are deteriorated or a crack of a bronze product may occur, thereby limiting the scope of the present invention. It is preferable to use.

Bismuth (Bi) is a silver white metal having an atomic number of 89 and an atomic weight of 208.9804, melting point of 271 ° C, specific gravity of 9.8, and boiling point of 1,560 ° C. At room temperature, the malleability, ductility is inferior, and oxidizing acid has a property of melting. When heated in air, it burns with blue-white flames. It can be used as a raw material to make alloys with lead (Pb), cadmium and tin (Sn).

Selenium (Se) is a solid having an element symbol Se, a melting point of 221 ° C and a boiling point of 685 ° C. There are many allotropes. The main ones are gray metal selenium (Se), red crystalline selenium (Se), and black glassy selenium (Se).

In the present invention, selenium (Se) may be added as needed and may be added in a content of 0.30 ~ 1.0% by weight. By using selenium (Se) within the range proposed in the present invention together with bismuth (Bi) or bismuth (Bi) alone, the machinability can be improved and economical.

Zinc (Zn) according to the present invention is used as an element to increase the moldability of the alloy and improve the pressure resistance, 8.0 to 13.0% by weight, preferably 8.0 to 10.0% by weight. When the content of zinc (Zn) is out of the range according to the present invention, strength and abrasion resistance are deteriorated or fluidity is deteriorated, which is not preferable because of poor workability.

In the present invention, silicon (Si) is used as the alloying element, and the silicon (Si) used is preferably 3.0 to 6.0% by weight, more preferably 3.0 to 4.0% by weight. If the content of silicon (Si) is less than 3.0% by weight, the castability is low, and within the range proposed in the present invention, the moldability is improved and the machinability, pressure resistance, and abrasion resistance can be improved.

Silicon (Si) is an easily available and inexpensive element and has an economical advantage in producing an alloy. That is, silicon (Si) is an element that exists a lot on earth after oxygen, and is usually present as SiO ₂ in combination with oxygen, and pure SiO ₂ crystal is quartz. Silica, a raw material for silicon (Si), is present in abundance around the world. The main minerals are quartz, high quartz, tridymite, amethys, etc.The main uses are for glass industry, ceramics, chemical industry, fillers, refractory, sodium silicate, steelmaking. Used in steelmaking, water purification industry, nonferrous smelting, cement industry, building materials, etc.

Generally, bronze alloy means tin bronze alloy and the content of tin (Sn) reaches 10% by weight but is used in the present invention at 1.5% by weight or less. Therefore, although only a sand casting was possible with the conventional tin bronze alloy, in the case of the bronze alloy according to the present invention, mold casting is possible by using silicon (Si) instead of tin (Sn). As described above, in the case of mold casting, the lead-free bronze alloy according to the present invention is annotated in terms of economy and quality because it has the advantages of excellent product quality compared to sand casting and simple equipment and excellent working environment. Compared to the sand casting product of bronze alloy containing

Nickel (Ni) in the present invention is added to increase the corrosion resistance of the alloy is preferably used less than 1.0% by weight.

Aluminum (Al) is preferably used in less than 1.50% by weight in consideration of mechanical properties deterioration.

In addition, the present invention is characterized by providing a method for producing a lead-free bronze alloy for die casting as shown in FIG.

The production method of lead-free bronze copper alloy for die casting according to the present invention

0.1 wt% or less of lead (Pb), 8.0-13.0 wt% of zinc (Zn), 3.0-6.0 wt% of silicon (Si), 1.50 wt% or less of tin (Sn), 1.0 wt% or less of nickel (Ni), bismuth (Bi) ) Injecting lead-free bronze alloy for die casting containing 0.7 ~ 2.50% by weight, 1.50% by weight of aluminum (Al), 0.30 ~ 1.0% by weight of selenium (Se), and the rest is composed of copper (Cu) and unavoidable impurities. step; Dissolving the temperature in the electric furnace to 1,130 ~ 1,230 ℃; Stirring and degassing the molten alloy; Removing the oxide floating in the slag state; Casting the molten alloy from which the slag oxide is removed with ingot It is configured to include.

Furthermore, the present invention provides a mold casting method using the prepared lead-free bronze alloy as shown in FIG. That is, in the mold casting method according to the present invention, after dissolving the lead-free bronze alloy for mold casting in a melting furnace, the mold casting temperature is maintained at 1,080 to 1,130 ° C., and a small gourd is used for the casting mold preheated to 170 to 230 ° C. It can be configured to include a mold casting step of injecting molten metal and a post-processing by separating the casting from the mold. 3 and 4 show examples of mold castings and precision mold castings manufactured using lead-free bronze alloys according to the present invention, and can be used in various products requiring excellent castability and machinability.

In addition, the lead-free bronze alloy for die casting has a feature of easy casting of precision dies with good castability.

Hereinafter, an example will be described based on the above-described point that the lead-free bronze alloy for mold casting according to the present invention can be manufactured in various contents.

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Example 1

The lead-free bronze alloy for die casting according to the present invention, which has improved mold casting and cutting property, is 85.55 wt% copper (Cu), 9.25 wt% zinc (Zn), 3.10 wt% silicon (Si), and 0.47 wt% tin (Sn). Nickel (Ni) 0.25% by weight, aluminum (Al) 0.003% by weight, bismuth (Bi) may be included, including 0.84% by weight, lead (Pb) 0.02% by weight, selenium (Se) 0.51% by weight.

Example 2

The lead-free bronze alloy for die casting according to the present invention, which has improved mold casting and cutting property, is 86.76 wt% of copper (Cu), 8.32 wt% of zinc (Zn), 3.22 wt% of silicon (Si), and 0.06 wt% of tin (Sn). Nickel (Ni) 0.01% by weight, aluminum (Al) 0.25% by weight, bismuth (Bi) 0.9% by weight, lead (Pb) 0.02% by weight, selenium (Se) may be configured to include 0.43% by weight.

Comparative Example 1

Conventional lead-free bronze alloy, 87.65 wt% copper (Cu), 5.80 wt% zinc (Zn), 5.26 wt% tin (Sn), 0.01 wt% nickel (Ni), 1.22 wt% bismuth (Bi), lead (Pb) 0.06 It comprises a weight percent.

Table 1 shows the alloy compositions of various forms shown in Examples 1 and 2 and Comparative Examples.

Table 2 is a hygienic safety standard inspection history of the lead-free bronze alloy casting for die casting according to the present invention.

As can be seen from Table 2, the lead-free bronze alloy casting according to the present invention can be variously applied to water-related products because the lead component is not detected and harmless to the human body.

In addition, as shown in Figures 3 and 4 it can be seen that the mold quality can be very excellent product quality.

Further, as shown in Figure 5 it can be seen that the cutting process is also very excellent in the form of the chip is cut finely.

Claims (7)

0.1 wt% or less of lead (Pb), 8.0-13.0 wt% of zinc (Zn), 3.0-6.0 wt% of silicon (Si), 1.50 wt% or less of tin (Sn), 1.0 wt% or less of nickel (Ni), bismuth (Bi) ) Lead-free bronze alloy for casting, characterized in that 0.7 to 2.50% by weight, aluminum (Al) 1.50% by weight, selenium (Se) 0.30 ~ 1.0% by weight, the remainder is copper (Cu) and unavoidable impurities. delete delete The method of claim 1,
0.1 wt% or less of lead (Pb), 8.0 to 10.0 wt% of zinc (Zn), 3.0 to 4.0 wt% of silicon (Si), 0.7 to 2.50 wt% of bismuth (Bi), and 1.50 wt% of aluminum (Al) Lead-free bronze alloy for casting, comprising selenium (Se) 0.30 ~ 1.0% by weight and the remainder is copper (Cu) and unavoidable impurities. The method of claim 1,
0.1 wt% or less of lead (Pb), 8.0 to 10.0 wt% of zinc (Zn), 3.0 to 4.0 wt% of silicon (Si), 1.50 wt% or less of tin (Sn), 1.0 wt% or less of nickel (Ni), Lead-free bronze for casting, characterized in that the bismuth (Bi) 0.7 ~ 2.50% by weight, aluminum (Al) 1.50% by weight or less, selenium (Se) 0.30 ~ 1.0% by weight, the remainder is copper (Cu) and unavoidable impurities alloy. delete delete

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