KR100787998B1 - Brass alloy for precision machining and method of manufacturing a wire using it - Google Patents

Abstract

A copper alloy for precision machining and a method of manufacturing a wire for machining using the copper alloy are provided, wherein the copper alloy for precision machining performs a drawing operation easily, can perform a high speed machining process, does not generate breakage of a wire, and has excellent automatic wire connecting properties. A copper alloy for precision machining has a composition comprising 37 to 45 wt.% of Zn, 0.0001 to 0.015 wt.% of Fe, and 0.0001 to 0.0035 wt.%(1 to 35 parts per million) of B with the balance being Cu and unavoidable impurities. A copper alloy for precision machining has a composition comprising 37 to 45 wt.% of Zn, 0.0001 to 0.015 wt.% of Fe, 0.0001 to 0.0035 wt.%(1 to 35 parts per million) of B, and further comprising at least one addition element of 0.01 to 0.3 wt.% of Al and 0.01 to 0.3 wt.% of Si with the balance being Cu and unavoidable impurities. A copper alloy for precision machining has a composition comprising 37 to 45 wt.% of Zn, 0.0001 to 0.015 wt.% of Fe, 0.0001 to 0.0035 wt.%(1 to 35 parts per million) of B, further comprising at least one addition element of 0.01 to 0.3 wt.% of Al and 0.01 to 0.3 wt.% of Si, and further comprising at least one addition element of 0.01 to 0.3 wt.% of Cr and 0.01 to 0.3 wt.% of Zr with the balance being Cu and unavoidable impurities.

Description

Brass alloy for precision machining and method of manufacturing a wire using it}

1 is a table showing the chemical composition of the copper alloy for precision processing according to an embodiment of the present invention.

2 is a view for explaining a manufacturing wire manufacturing method using the copper alloy for precision processing according to the present invention.

Figure 3 is a table schematically showing the effect of improving the physical properties of the conventional precision machining copper alloy and precision machining copper alloy according to an embodiment of the present invention.

Figure 4 is a table comparing the adhesion amount of foreign matter after the cutting process of the electric wire for electrical discharge processing using the conventional precision copper alloy and the precision machining copper alloy according to an embodiment of the present invention.

5 to 8 is a table comparing the surface roughness of the processing material after the cutting process of the electric wire for electrical discharge machining using the conventional precision copper alloy and the precision machining copper alloy according to an embodiment of the present invention.

9 and 10 are scanning electron microscope comparison pictures of cut surfaces of workpieces.

11 is a scanning electron microscope comparison photograph of the surface of the electrode wire for electrical discharge machining.

12 is a photograph for explaining the effect of the addition of iron (Fe) in the copper alloy for precision machining according to the present invention.

The present invention relates to a precision processing copper alloy and a method for manufacturing a processing wire using the copper alloy, which is easy to draw, high-speed processing, there is no disconnection, excellent copper connection for precision processing and its copper alloy It relates to a method for producing a wire for processing using.

The processing speed of the electrode wire for electric discharge machining using copper (Cu) and zinc (Zn) -based copper alloys improves with increasing zinc content, but cold workability is achieved because hard beta (β) phase is formed with increasing zinc content. This deterioration problem occurs. Typically, a single alloy wire containing about 35% zinc (Cu-35 wt% Zn alloy, so-called 65/35 brass wire) was mainly used as an electrode wire. However, as high speed processability is required in terms of productivity, high zinc-containing copper alloy wires for precision machining, such as copper alloy wires containing 40% by weight or more of Zn, have a tendency to be developed to obtain a strong wire.

However, if the zinc content is 38% by weight or more, the beta (β) phase is inevitably formed, and thus the structure of the wire rod becomes a mixed structure of the alpha (α) and beta (β) phase, and thus the beta (β) from the wire rod during electric discharge machining. The phases tend to fall, which lowers the discharge machining efficiency, and the metal powder and gas, which are beta (β) phases, destabilize the discharge of the electrode wires, thereby causing the discharge machining speed and the machining precision to be lowered.

  In addition, although the copper alloy electrode wire rises to a temperature of several hundred degrees during electric discharge machining, as the thermal load and the processing speed of the electrode wire itself increase, tensile strength at the high temperature is required as the electrode load is applied together, but general copper alloy electrode wire is required. Since the high temperature strength is not high, increasing the discharge machining current in order to increase the discharge machining speed causes a problem of disconnection of the electrode line due to an increase in temperature and tension load of the electrode line.

In addition, a method of increasing the zinc content or adding a specific alloying element and copper alloy wire which has improved the electric discharge machining characteristics by plating the surface of the alloy wire has been developed and used in part, but it has not been maintained at high temperature strength characteristics or an alloying element. Due to problems such as segregation and non-uniformity of plating, the wires are not frequently increased due to frequent disconnection during the drawing operation, or the failure of the surface of the mold, causing the surface defects of the wire, and the increase of the manufacturing cost due to the increase of the production process.

Accordingly, there is a need to develop a copper alloy for precision processing by increasing zinc content, suppressing metal powder and gas generation even by adding an alloying element, and having high temperature strength even in high zinc content, without disconnection of electrode wires.

The object of the present invention is to solve such problems in the related art, and it is easy to draw, high-speed processing, there is no disconnection, and the wire for processing using the copper alloy for precision processing and its copper alloy excellent in the automatic connection. It is to provide a method for producing.

Copper alloy for precision processing according to the present invention comprises 37 to 45% by weight of Zn, 0.0001 to 0.015% by weight of Fe, 0.0001 to 0.0035% by weight (1 to 35ppm) of B (boron),
The remaining weight percent is characterized by having a composition consisting of copper (Cu) and unavoidable impurities.

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Another type of precision machining copper alloy according to the present invention includes 37 to 45% by weight of Zn, 0.0001 to 0.015% by weight of Fe, and 0.0001 to 0.0035% by weight (1 to 35 ppm) of B (boron),
0.01 to 0.3% by weight of Al, 0.01 to 0.3% by weight of at least one additional element of Si further included,
The remaining weight percent is characterized by having a composition consisting of copper (Cu) and unavoidable impurities.

Another type of precision machining copper alloy according to the present invention comprises 37 to 45% by weight of Zn, 0.0001 to 0.015% by weight of Fe, and 0.0001 to 0.0035% by weight (1 to 35 ppm) of B (boron),
0.01 to 0.3% by weight of Al, 0.01 to 0.3% by weight of at least one additional element of Si further included,
0.01 to 0.3% by weight of Cr, 0.01 to 0.3% by weight of Zr further comprises at least one additional element,
The remaining weight percent is characterized by having a composition consisting of copper (Cu) and unavoidable impurities.

The manufacturing method of the wire for precision machining according to the present invention includes a casting step of manufacturing a casting billet to have an alloy composition of the copper alloy for precision processing of the type according to the present invention;

A first heat treatment step of hot extruding the cast billet at 650 ° C. to 800 ° C. and then water-cooling the extruded coil;

Drawing the wire rod of a diameter smaller than the extrusion coil from the water-cooled extrusion coil;

A second heat treatment step of recrystallizing heat treatment of the wire rod processed in the drawing step at 400 ° C. to 600 ° C. for 0.5 to 3 hours;

A third heat treatment step of heat-treating the wire rod recrystallized in the second heat treatment step several times, followed by annealing for 0.5 to 3 hours at 400 ° C. to 600 ° C .; And

And reprocessing the wire rod heat-annealed in the third heat treatment step several times, followed by drawing into final fine wires, followed by instant low temperature annealing heat treatment at 200 ° C to 400 ° C.

Hereinafter, the present invention will be described in detail.

1 is a table showing the chemical composition of the copper alloy for precision processing according to an embodiment of the present invention. 2 is a view for explaining a manufacturing wire manufacturing method using the copper alloy for precision processing according to the present invention.

Referring to Figure 1, one embodiment of the copper alloy for precision processing according to the present invention is a copper alloy as a base alloy of copper, providing a copper alloy wire excellent in drawing workability or discharge workability even if the zinc content is reduced up to 45% by weight can do. In order to maintain these characteristics, 37 to 45% by weight of Zn, 0.0001 to 0.015% by weight of Fe, and 0.0001 to 0.0035% by weight (1 to 35 ppm) of B (boron) are included, and 0.01 to 0.3% by weight of the additive element. Al, 0.01 to 0.3% by weight of Si, 0.01 to 0.3% by weight of Cr, 0.01 to 0.3% by weight of Zr is characterized in that it further comprises at least one or more additional elements.

In the present invention, the content of zinc (Zn) was limited to 37 to 45% by weight, for the following reasons. In other words, when zinc contained less than 37% by weight in terms of the speed and workability due to the heat of vaporization of zinc, the improvement in processing speed was not satisfactory as compared with conventional copper alloys. On the other hand, when zinc exceeds 45% by weight, a strong beta (β) phase structure or a gamma (γ) phase structure is formed, so that the malleability of the alloy is low and the hardness is high, there is a problem that the drawability is bad.

In addition, in the present invention, the iron (Fe) content was limited to 0.0001 to 0.015% by weight, which is related to grain growth of the alloy. In other words, as a small amount of iron (Fe) is added in terms of the effect of finer grain boundary, hot workability and strength improvement during solidification of the alloy, it is possible to improve the cold workability at the time by delaying grain growth at the time of heat treatment, which is the improvement of workability during extrusion and post-processing. In addition, it is more effective for grain refinement together with boron (B) described later. However, when the content of the iron (Fe) exceeds 0.015% by weight, the grain size refinement effect is reduced during the solidification of the alloy and during the post-process heat treatment, and a high melting point compound is formed inside the alloy to inhibit wire workability, thereby causing disconnection. In addition to reducing the productivity by acting as a cause causing the problem that the machining speed improvement effect during the discharge machining can not be expected. On the other hand, when the iron (Fe) content is less than 0.0001% by weight, the grain refinement effect was hardly exhibited during solidification of the alloy. Figure 12 shows the change in the microstructure according to the iron (Fe) content applied in the present invention, the alloy structure of the iron (Fe) content of 0.015% by weight or less at the same magnification of the iron (Fe) content of 0.015% by weight It can be seen that it has a finer grain than the structure of the alloy exceeding.

  In addition, in the present invention, by adding the boron (B) to refine the structure from the casting billet state of the alloy to refine the crystal grains of the final busbar, even if the zinc content is increased to 45% by weight, the discharge of the final product with improved workability It is effective in obtaining the improvement of workability. In addition, by maximizing the effect of the elements added to increase the strength of the alloy material, it solves the problem of defects and disconnection occurring during hot and drawing operations, and in particular, to prevent the phenomenon of disconnection during the cutting operation during the discharge processing of the final product and There is an effect of increasing the processing speed to improve productivity. In the present invention, when the content of boron (B) is added to 0.0035% by weight or less, a good effect could be obtained. When the boron content is added more than 0.0035% by weight, the active reaction of the added boron causes oxidation of zinc and other additives during dissolution and casting, which makes it difficult to adjust alloying components and worsens casting workability. There is a problem. In addition, due to the severe reactivity of boron, there is a problem in that the occurrence of internal defects in the tissue due to the formation of pores in the cast billet and oxides of other additive elements, etc., causing disconnection and surface defects during hot and cold working. On the other hand, increase in the zinc content to obtain the strength of the material without adding boron has a problem of fresh workability, there is a limit. Therefore, in order to solve this problem, a method of obtaining material strength by other additive elements may be used, but there are limitations in improving the properties of the final product with only other additive elements. Therefore, the addition of boron is essential, at least 0.0001% by weight or more must be contained in order to obtain the effect by the addition of boron. In the present invention, it is possible to increase the content of zinc by adding boron, by providing a copper alloy for precision processing having the most excellent properties by selectively adding the content of a certain additional element to the minimum to improve the fresh workability to improve the productivity workability and final Economical effects such as user's automatic connection and discharge processing speed can be realized simultaneously.

In addition, the copper alloy for precision processing according to the present invention contains 0.01 to 0.3% by weight of aluminum (Al). The reason why the aluminum is added is that it is effective in improving the workability of the alloy, maintaining strength during electrical discharge machining, and automatic connection. However, when the content of aluminum is less than 0.01% by weight, there is no effect of improving the workability of wire drawing, and it is difficult to maintain strength during electric discharge machining, and there is a problem of less effect of automatic connection and dimensional accuracy. On the other hand, when the content of aluminum exceeds 0.3% by weight, the hardness of the alloy is increased, the wire workability is poor, the effect of automatic connection and dimensional precision is insignificant, there is a problem that the effect is not improved in maintaining strength during electrical discharge machining.

In addition, the copper alloy for precision processing according to the present invention contains 0.01 to 0.3% by weight of silicon (Si). The effect of the silicon improves the workability of the alloy, and maintains the strength of the alloy during electrical discharge machining. However, when the silicon content is less than 0.01% by weight, the effect of improving the workability of the alloy is small, and there is a problem in that the effect of maintaining the strength during discharge processing and preventing the adhesion of copper (Cu) to the workpiece is low. On the other hand, when the content of the silicon exceeds 0.3% by weight, there is a problem that the drawability of the alloy is worsened and the improvement of disconnection during discharge processing is not expected.

On the other hand, the copper alloy for precision processing according to the present invention may contain 0.01 to 0.3% by weight of chromium (Cr). The chromium has an effect of maintaining the strength of the alloy during electrical discharge machining and preventing the adhesion of copper (Cu) to the workpiece. However, when the content of chromium is outside the range of 0.01 to 0.3% by weight, there is no effect of maintaining strength during discharge processing, and there is no effect of preventing copper (Cu) from adhering to the workpiece. There is a problem that does not affect.

On the other hand, the copper alloy for precision processing according to the present invention may contain 0.01 to 0.3% by weight of zirconium (Zr). The zirconium has an effect of maintaining strength during workability and electrical discharge machining of the alloy. When the content of the zirconium is less than 0.01% by weight, not only the effect of improving the fresh workability of the alloy is small, but there is a problem in that there is no effect of improving the strength maintenance during discharge processing. On the other hand, when the content of the zirconium exceeds 0.3% by weight, the effect of improving the drawing workability of the alloy is inferior, and it is difficult to improve the strength maintenance during electric discharge machining, thereby reducing the processing speed.

Until now, the copper alloy for precision processing according to the present invention described above is an alloy made of the aforementioned elements and copper (Cu), but a trace amount of impurities may be inevitably included.

Using the copper alloy for precision machining according to the present invention, a method for producing a wire for precision machining is as follows.

That is, referring to FIG. 2, the method for manufacturing the precision machining wire includes a casting step S1, a first heat treatment step S2, a drawing step S3, a second heat treatment step S4, and a first step. It includes three heat treatment steps (S5) and a reprocessing step (S6).

In the casting step (S1), the casting billet is manufactured by melting and casting an alloy having an alloy composition according to the present invention.

In the first heat treatment step (S2), the casting billet manufactured in the casting step (S1) is hot-extruded at a temperature of 650 ℃ ~ 800 ℃ and rapidly cooled by water-cooling the extruded coil to produce fine grains in the alloy structure do.

In the drawing step S3, a wire drawing process for forming a wire rod having a diameter of about 9 mm from the water-heat-treated alloy in the first heat treatment step S2 by drawing and a wire rod having a diameter smaller than the diameter of the wire rod formed by the wire drawing process. The middle wire process of forming by drawing is performed.

In the second heat treatment step (S4), the wire rod processed in the drawing step (S3) is recrystallized and heat treated at 400 ° C. to 600 ° C. for 0.5 hours to 3 hours. At this time, if it is lower than the recrystallization heat treatment temperature range, recrystallization is not performed, and if it is higher than that, the structure becomes coarse and thus may not have desired mechanical properties.

In the third heat treatment step (S5) after the wire rod re-crystallized heat treatment in the second heat treatment step (S4) several times, the annealing heat treatment at 400 ℃ ~ 600 ℃ 0.5 ~ 3 hours.

In the reprocessing step (S6) after the wire rod heat-treated annealing in the third heat treatment step (S5) a number of times, the wire is drawn to a final fine wire (細線) to instantaneous low temperature annealing heat treatment at 200 ℃ ~ 400 ℃.

The results of evaluating the performance of the copper alloy for precision machining according to the present invention using the precision machining wire manufactured by such a manufacturing method will be described in detail below.

First, Figure 3 is a table schematically showing the effect of improving the physical properties of the conventional precision machining copper alloy and precision machining copper alloy according to an embodiment of the present invention. Referring to Figure 3, using a conventional electrode (1) (2) and the electrode wire of 0.25mm in diameter made of the copper alloy for precision processing according to the present invention, the relative discharge processing speed, ease of wrought processing, disconnection frequency, zinc powder generation It can be seen that the evaluation results of the state and automatic connection, as can be seen in Figure 3, the copper alloy for precision machining according to the present invention is superior in all the results evaluated than the conventional copper alloy electrode wire (1) (2) Can be. 3 shows that the relative value is a relative index of comparison with the prior art (1).

Figure 4 is a table comparing the adhesion amount of foreign matter after the cutting process of the electric wire for electrical discharge processing using the conventional precision copper alloy and the precision machining copper alloy according to an embodiment of the present invention. In FIG. 4, the amount of the surface to be processed is the relative comparative index of 100 according to the related art (1). Referring to Figure 4, using a discharge electrode electrode and a conventional electrode wire made of a copper alloy wire according to the invention having a diameter of 0.25mm diameter, 100mm SKD-11 (mold alloy steel) specimens of a thickness of 97mm as a workpiece material As a result of comparing the foreign matter adhesion amount on the surface of the workpiece after cutting by electric discharge machining, the foreign matter adhesion amount of the workpiece material using the wire made of the copper alloy for precision machining according to the present invention is up to 18% than that of the conventional (1). It can be seen that less adsorption. In addition, referring to Figure 4, as a result of comparing the dimensional change of the workpiece, it can be seen that the case of using the copper alloy for precision machining according to the present invention is the smallest dimensional change of the workpiece.

5 to 8 are graphs showing the results of comparing the surface roughness of the workpiece. 5 to 8 show a conventional copper alloy and a copper alloy for precision processing according to the present invention, which is processed into a wire having a diameter of 0.25 mm, and then using the wire as an electrode wire, two kinds of materials to be processed, that is, SKD-11 having a thickness of 97 mm; The Inconel 718 material was cut 100 mm and the surface roughness of the workpiece was measured. SJ-301 was used as the illuminance measuring instrument, and the average roughness (Ra) and the maximum height illuminance for each of the two standard values of cut-off were defined as λc = 0.8mm and λc = 2.5mm. (Ry) was measured. 5 and 6 show the average roughness Ra and the maximum height roughness Ry after processing SKD-11 and Inconel 718 for the workpiece, respectively, when λc = 0.8mm. 8 shows average roughness (Ra) and maximum height roughness (Ry) after SKD-11 and Inconel 718 were processed for λc = 2.5mm, respectively. 5 to 8, it can be seen that the average roughness Ra and the maximum height roughness Ry of the material to be processed have the lowest values when the copper alloy for precision machining according to the present invention is used. That is, it can be seen that the surface state of the workpiece is the best.

9 and 10 are scanning electron microscope (SEM) comparison photographs of the cut surfaces of the workpiece. FIG. 9 illustrates a case where SKD-11 is used as a workpiece and FIG. 10 illustrates a case where Inconel 718 is used as a workpiece. 9 and 10, it can be seen that the case of cutting with a wire electrode wire made of a copper alloy for precision machining according to the present invention has less unevenness and uniformity on the surface of the workpiece.

11 is a scanning electron microscope comparison photograph of the surface of the electrode wire for electrical discharge machining. FIG. 11 shows a photograph of observation of the surface of the electrode line after cutting SKD-11 as a work material with a scanning electron microscope. Referring to FIG. 11, it can be seen that the surface state of the wire electrode wire made of the copper alloy for precision machining according to the present invention is maintained even after cutting of the workpiece.

As described above, referring to the photograph of FIGS. 9 to 11, it can be seen that the copper alloy for precision machining according to the present invention has excellent cutting performance, that is, machinability for the workpiece, and also has excellent durability for processing wire. .

As described above, the precision machining copper alloy and the manufacturing method of the copper alloy for precision machining according to the present invention, compared with the conventional precision machining copper alloy, the strength is improved by increasing the zinc content not only good durability, but also by adding an alloying element freshness And, the workability of the material, automatic connection properties, etc. are relatively excellent, and there is an effect of providing an excellent precision copper alloy that hardly generates zinc powder during processing.

As mentioned above, although the present invention has been described with reference to preferred embodiments, the present invention is not limited to such an example, and various forms of embodiments may be embodied within the scope without departing from the technical spirit of the present invention.

As described above, according to the present invention, the zinc content is increased compared to the conventional copper alloy for precision machining, thereby improving the high temperature strength and durability, and also adding the alloying element to improve the freshness, and suppress the generation of metal powder and gas. There is an effect of providing a method for producing a processing wire using the copper alloy for precision processing and the copper alloy without disconnection of the electrode wire.

Claims (4)

37-45 wt% Zn, 0.0001-0.015 wt% Fe, and 0.0001-0.0035 wt% (1-35 ppm) B (boron), A copper alloy for precision machining, wherein the remaining weight% has a composition composed of copper (Cu) and unavoidable impurities. 37-45 wt% Zn, 0.0001-0.015 wt% Fe and 0.0001-0.0035 wt% (1-35 ppm) B (boron), 0.01 to 0.3% by weight of Al, 0.01 to 0.3% by weight of at least one additional element of Si further included, A copper alloy for precision machining, wherein the remaining weight% has a composition composed of copper (Cu) and unavoidable impurities. 37-45 wt% Zn, 0.0001-0.015 wt% Fe, and 0.0001-0.0035 wt% (1-35 ppm) B (boron), 0.01 to 0.3% by weight of Al, 0.01 to 0.3% by weight of at least one additional element of Si further included, 0.01 to 0.3% by weight of Cr, 0.01 to 0.3% by weight of Zr further comprises at least one additional element, A copper alloy for precision machining, wherein the remaining weight% has a composition composed of copper (Cu) and unavoidable impurities. The method according to any one of claims 1 to 3, Casting to produce a casting billet by casting an alloy having an alloy composition; A first heat treatment step of hot extruding the cast billet at 650 ° C. to 800 ° C. and then water-cooling the extruded coil; Drawing the wire rod of a diameter smaller than the extrusion coil from the water-cooled extrusion coil; A second heat treatment step of recrystallizing heat treatment of the wire rod processed in the drawing step at 400 ° C. to 600 ° C. for 0.5 to 3 hours; A third heat treatment step of heat-treating the wire rod recrystallized in the second heat treatment step several times, followed by annealing for 0.5 to 3 hours at 400 ° C. to 600 ° C .; And After the wire is heat-treated a plurality of times the annealing heat treatment in the third heat treatment step and the final fine wire (細線) and reprocessing step of instantaneous low temperature annealing heat treatment at 200 ℃ ~ 400 ℃; manufacturing of copper alloy for precision machining Way.

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