KR100864910B1 - A free-cutting copper alloy - Google Patents

Abstract

The present invention relates to a free cutting copper alloy containing calcium and silicon.

The free-cutting copper alloy according to the present invention, the free-cutting copper alloy according to the present invention comprises copper (Cu), zinc (Zn), calcium (Ca) and silicon (Si), the copper (Cu) And zinc (Zn) alloy is 0.1 to 1.5 wt% of calcium (Ca), silicon (Si) is characterized in that the addition of 0.21 to 3.07 wt%. According to the free-cutting copper alloy configured as described above, there is an advantage that the intermetallic compound in which calcium (Ca) and silicon (Si) are combined is present in the base, thereby improving industrial machinability.

Calcium, Silicon, Containing, Free Cutting, Copper Alloy

Description

Free-cutting copper alloy

1 is a real photograph showing the change in shape of the chip cut with high and low machinability for copper alloy.

Figure 2 is a photograph showing the shape of the chip formed when drilling a lead-containing copper alloy generally used widely.

Figure 3a is a photograph showing the appearance of the copper alloy casting block made for the machinability test of the present invention

3B is a photograph showing a drill tool applied to form chips from the casting block of FIG. 3A.

Figure 4 is a table showing the weight ratio of the configuration of the embodiment in the free-cut copper alloy according to the present invention.

5 is an enlarged optical micrograph of the outer surface of the cast block produced through the first to fourth embodiments of the free cutting copper alloy according to the present invention.

Figure 6 is a scanning electron micrograph of the enlarged outer surface of the casting block produced through the first to fourth embodiments of the free-cutting copper alloy according to the present invention and subjected to component inspection.

7 is an enlarged photograph showing a state of a chip formed when drilling a casting block cast through the first to fourth embodiments shown in FIG.

8 is a table comparing the torque generated in the drill block and the torque generated in the pure copper block produced by the casting block produced in Examples 1 to 3 of the present invention.

9 is a table showing the weight ratio of another embodiment performed by changing the weight ratio of zinc, calcium and silicon after fixing the weight ratio of copper in the free-cut copper alloy according to the present invention.

FIG. 10 is a microstructure photograph showing the surface of a free cutting copper alloy made under the conditions of another embodiment shown in FIG.

Figure 11 is a table comparing the torque generated in the drill block and the torque generated during the casting of the cast block produced in Examples 5 to 7 of the present invention.

The present invention relates to a copper alloy, and more particularly to a free-cutting copper alloy containing calcium (Ca) and silicon (Si) to improve the machinability.

Copper (Cu) is one of the nonferrous metal materials, and various additives are added according to the purpose of use, and are used in various fields. That is, phosphor bronze made by adding phosphorus (P) of less than 1% to increase the hardness and strength of the alloy containing copper and improve the wear resistance is used as a processing material for plates, wires, etc., which use high elasticity. It is used as casting for ship parts and chemical machine parts.

In addition, aluminum bronze with a small amount of aluminum (Al) added to copper has not been widely supplied until recently due to problems such as melt casting technology and self snnealing, but according to recent metallographic requirements and advances in melt casting technology. Its use is gradually expanding.

Also known as manganese (Mn) bronze, high-strength brass is an alloy of 1 to 3% of manganese in brass, and in addition to copper (Cu), aluminum (Al), iron (Fe), nickel (Ni), and tin (Sn). By adding elements such as), it is possible to optimize the required strength, corrosion resistance and seawater resistance.

In recent years, as the use of copper is expanded, studies are being actively conducted to increase the workability of copper alloys. In other words, copper has a high elongation, so it is difficult to process because it sticks to the tool at the time of cutting with a tool.

For example, in the early days of active research to improve the workability of copper alloys, 2.5 to 3.7 wt% of lead (Pb) was added to copper to make lead brass. However, lead (Pb) has been found to be harmful to the human body, which leads to strong restrictions on the use of lead, and thus research on alternative additives of lead is conducted.

As a result, high-cut lead-free brass was developed in which bismuth (Bi) was added to copper. However, bismuth has been reluctant to use because it is not clearly identified as harmful to the human body.

In addition, lead (Pb) and bismuth (Bi) can not be recovered from copper alloy by ordinary smelting and refining, and high energy is used for recovery by physical method, so it is invested to recycle lead and bismuth. There is a problem that the cost is increased.

In addition, as the recovery of lead and bismuth is lowered, the recovery of copper is also lowered, and since the entire amount of copper is dependent on imports, it is not preferable in view of recycling of copper.

An object of the present invention is to solve the above problems, more specifically calcium (Ca) and copper (Ca) which can improve the machinability in the copper alloy matrix by containing a predetermined calcium (Ca) and silicon (Si) and By providing the intermetallic compound which silicon (Si) couple | bonded, it is providing the high machinability copper alloy which improved machinability.

Another object of the present invention is to include a predetermined calcium (Ca) and silicon (Si) in the copper (Cu) to increase the recovery rate of the calcium (Ca) and silicon (Si) to enable the recyclable copper alloy Is to provide.

The high machinability copper alloy according to the present invention for achieving the above object is characterized by comprising copper (Cu), zinc (Zn), calcium (Ca) and silicon (Si).

The calcium (Ca) and silicon (Si) is added to a brass base, which is an alloy of copper (Cu) and zinc (Zn), on an alpha (α) single phase or a composite base mixed with alpha (α) and beta (β) phases. It is done.

When calcium (Ca) and silicon (Si) are added, CaSi ₂ , CaSi, and Ca ₂ Si particles are produced.

The copper (Cu) is 60 to 80 wt%, calcium (Ca) is 0.1 to 1.5 wt%, silicon (Si) is 0.21 to 3.07 wt%, the balance (iron) containing zinc (Zn), It is characterized by being aluminum (Al) and carbon (C).

It is characterized by being formed by any one of the process of extrusion, rolling, drawing.

According to the present invention manufactured with such a configuration, there is an advantage that the hardness is increased, the elongation and tensile strength are reduced, and the cutting workability is improved.

In general, in the case of copper alloy, there is no numerical definition of the machinability, and it defines the good and bad machinability according to the shape and length of the cut chip.

Hereinafter, a cutting processability of the copper alloy will be briefly described with reference to the accompanying drawings.

FIG. 1 is a real photograph showing a change in shape of a chip as the cutting processability of copper alloy is high and low, and is extracted from the contents of a copper handbook (Jeseph, Gunter, Kundig, J.A. Konrad ASM International).

As illustrated in FIG. 1, the chip shown in Type III is a shape of a chip made when high-purity copper is drilled. In this way, when the chip is not broken and the dried state is maintained, it can be seen that the ductility of the workpiece is high, and as a result of the ductility of the workpiece, it sticks to the drill tool, resulting in deterioration of workability.

In Type II, the chip is generally short but has a rounded shape. It can be seen that in the form of a chip such as a copper alloy having a high hardness and strength, there is room for improvement in cutting property by adjusting the conditions in the cutting operation.

In addition, the shape of the chip shown in Type I is the most ideal shape for the machinability of the copper alloy. In other words, the chip shown in Type I is a state in which lead (Pb), bismuth (Bi), sulfur (S), tellurium (Te), and the like are added to a copper alloy, which is a work, and the chips are fine and evenly formed. It can be seen that it is easily discharged from the workpiece without sticking when it is to be machined.

However, since the workpieces that make the shape of chips such as Type I are expensive copper alloys that are not generally used, the present invention is similar to the shape of chips of copper alloys (lead-containing copper alloys) which are widely recognized for cutting processability. Experiments were made with varying conditions.

That is, in the present invention, calcium (Ca) and silicon (Si) are added to the copper, and then cast and manufactured to form a block having a rectangular parallelepiped shape, and the shape of the chip formed when the block is drilled is shown in FIG. Various examples were performed by adjusting the addition amount of calcium and silicon to be similar to copper alloy).

Figure 3a is a photograph showing the appearance of the casting block containing a copper (Cu) -zinc (Zn) -calcium (Ca) -silicon (Si) made for the machinability test of the present invention, Figure 3b A photograph is shown showing a drill applied to form a chip of the casting block of 3a.

The drill of FIG. 3B was molded from High-Speed Steel (HSS) and has an 8 mm diameter.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 4 to 6.

Figure 4 is a table showing the weight ratio of the configuration of the embodiment in the free-cutting copper alloy according to the present invention, Figure 5 is prepared through the first to fourth embodiments of the free-cutting copper alloy according to the present invention An enlarged microstructure photograph of the casting block is shown.

6 shows an electron micrograph showing the composition of particles by performing compositional analysis using an electron microscope in the microstructure photograph shown in FIG. 5.

As shown in the drawings, looking at Examples 1 to 4 of the present invention, the weight ratio of zinc (Zn) in the copper alloy is fixed to 40wt%, calcium (Ca) is contained in the weight ratio of 0.1 to 1.5wt% Silicon (Si) is contained in a weight ratio of 0.21 to 3.07 wt%. And remainder is copper (Cu).

In addition, the copper alloy contains a very small amount of iron (Fe), aluminum (Al) and carbon (C).

Looking at the surface of the cast block prepared in the above composition by scanning electron micrographs, as shown in Figure 5, it can be seen that the Ca-Si compound is homogeneously distributed in the form of needles, the addition amount of calcium and silicon It can be seen that as the ratio of Ca-Si compound increases.

And, Figure 7 is an enlarged picture showing the state of the chip formed when drilling the casting block shown in Figure 5, Figure 8 is a drill block produced by the first to third embodiments of the present invention A table comparing torque generated during machining with torque generated in pure copper blocks is shown.

As shown in FIG. 7, it can be seen that as the content of calcium (Ca) and silicon (Si) increases, the shape of the chip formed by the drilling process approaches the type I of FIG. 1. This can be said to indicate that the workability is improved in the case of the copper alloy containing calcium and silicon.

Copper alloy prepared as described above can be seen through the machining process through the torque (Torque) transmitted to the drill tool as the depth is deepened during machining using the drill tool. That is, as shown in FIG. 8, in the case of pure copper blocks, when the cutting process is performed using the drill tool, the torque transmitted to the drill tool increases as the depth increases.

On the other hand, in Examples 1 to 3 of the present invention, it can be confirmed by the table that the phenomenon in which the torque transmitted to the drill tool increases rapidly as the calcium-silicon compound is uniformly distributed in the casting block.

Hereinafter, another embodiment of the present invention will be described with reference to FIGS. 9 to 11.

9 is a table showing the weight ratio of another embodiment performed by changing the weight ratio of zinc, calcium and silicon after fixing the weight ratio of copper in the free-cut copper alloy according to the present invention, Figure 10 is a condition of another embodiment shown in FIG. The microstructured micrograph showing the surface of the free-cutting copper alloy made of the present invention, Figure 11 is a torque generated when drilling the cast block produced in Examples 5 to 7 of the present invention and the torque generated in the pure copper block Is a table comparing.

As shown in these figures, in the copper alloys according to Examples 5 to 8, the content of calcium (Ca) is changed to 0.1 to 1.5 wt% while the content of copper (Cu) is fixed at 80 wt%. At the same time, the content of silicon (Si) was also changed to 0.21 to 3.07wt%.

At this time, the addition amount of other iron (Fe), aluminum (Al) and carbon (C) also changes, but it is negligible because it is a very small amount, it was configured to include the residual zinc (Zn) in the copper alloy.

As a result of enlarging each of the cast block surfaces prepared under the above conditions with a scanning electron microscope, it can be seen that Ca-Si compounds rapidly increase as the calcium and silicon contents increase as shown in FIG. 10. Considering that the Vickers hardness of lead-containing copper alloys such as Vickers hardness shown in FIG. 9 is 80, it can be seen that the hardness of the copper alloy prepared by Examples 5 to 8 of the present invention is improved.

When the copper alloys prepared in Examples 5 to 8 were drilled using a drill tool having a diameter of 10 mm, the torque transmitted to the drill tool was measured, and when compared with pure copper blocks. Low torque overall.

This is because when the drill is drilled into the copper alloy using the drill tool, the chip is shorted and not taken out, and is taken out of the copper alloy. For this reason, the chip sticking to the drill tool is reduced, and thus cutting processability can be improved.

The scope of the present invention is not limited to the above-exemplified embodiments, and many other modifications based on the present invention may be made by those skilled in the art within the above technical scope.

For example, in the embodiment of the present invention, various embodiments were configured by changing the content of the remaining components in a state where the content of zinc was fixed, but copper in a state where the content of calcium and silicon was fixed within a range containing calcium and silicon. And by changing the content of zinc, it is obvious that a free-cutting copper alloy can be produced in accordance with the intended use.

In addition, in the embodiment of the present invention, the free cutting copper alloy is configured to be molded by casting, but may be formed by various processing such as extrusion, rolling, drawing.

According to the free-cutting copper alloy according to the present invention as described in detail above, the copper alloy was configured to contain predetermined calcium (Ca) and silicon (Si).

Accordingly, there is an advantage in that the hardness is increased, the elongation and tensile strength are reduced and the cutting workability is improved.

In addition, the copper alloy produced by the present invention has the advantage of reducing the manufacturing cost because it is possible to re-recycling by separating the copper and calcium and silicon from the chip separated by the cutting tool.

In addition, calcium and silicon added to the free cutting copper alloy of the present invention is harmless to the human body has the advantage of improving the work safety of the operator.

Claims (6)

delete delete delete 100% by weight, 60% to 80% by weight of copper (Cu), 0.1% to 1.5% by weight of calcium (Ca), 0.21% to 3.07% by weight of silicon (Si), and the remainder is composed of zinc (Zn). Copper alloy. delete The method of claim 4, wherein A free cutting steel copper alloy, characterized in that the CaSi ₂ , CaSi, Ca ₂ Si particles are formed according to the calcium (Ca) and silicon (Si) composition.

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