ELECTRODE WIRE FOR ELECTRO-DISCHARGE MACHINING AND METHOD FOR MANUFACTURING THE SAME

Abstract

The invention discloses an electrode wire for electro-discharge machining. The electrode wire comprises a core material and a surface metal layer, and a transition layer is arranged between the core material and the surface metal layer, wherein the core material comprises a brass alloy as a main component, the surface metal layer comprises zinc oxide, the transition layer comprises a copper-zinc alloy as a main component, and irregular cracks are distributed on the zinc oxide layer. The invention also provides a method for manufacturing the electrode wire, which can improve the cutting efficiency, machining yield and cutting quality of the manufactured electrode wire.

Claims

1. An electrode wire for electro-discharge machining, comprising a core material and a surface metal layer, a transition layer being arranged between the core material and the surface metal layer, wherein, the core material comprises a brass alloy as a main component and a balance amount of zinc and inevitable impurities; and the surface metal layer comprises zinc oxide as a main component and a balance amount of copper and inevitable impurities, a transition layer is arranged between the core material and the surface metal layer, the transition layer comprises a copper-zinc alloy as a main component, and irregular cracks are distributed on the zinc oxide layer; and the core material has a diameter of 0.65-1.48 mm, the surface metal layer has a thickness of 0.45-10.23 m, the maximum thickness of the cracks is less than or equal to 4.5 m, and the maximum spacing of the cracks is 17 m.

2. The electrode wire for electro-discharge machining according to claim 1, wherein the content of the brass alloy is 48-72 wt % and the impurity content is less than or equal to 0.38 wt % in the core material; and the content of the zinc oxide is 65-87 wt % and the balance content is less than or equal to 0.15 wt % in the surface metal layer.

3. A method for manufacturing an electrode wire for electro-discharge machining, wherein the electrode wire comprises a core material and a surface metal layer, and a transition layer is arranged between the core material and the surface metal layer, wherein the core material comprises a brass alloy as a main component and a balance amount of zinc and inevitable impurities; the surface metal layer comprises zinc oxide as a main component and a balance amount of copper and inevitable impurities, a transition layer is arranged between the core material and the surface metal layer, the transition layer comprises a copper-zinc alloy as a main component, and irregular cracks are distributed on the zinc oxide layer; and the core material has a diameter of 0.65-1.48 mm, the surface metal layer has a thickness of 0.45-10.23 m, the maximum thickness of the cracks is less than or equal to 4.5 m, and the maximum spacing of the cracks is 17 m; and the method for manufacturing the electrode wire for electro-discharge machining comprises the following steps: step (1): after raw materials containing copper and zinc are qualified by chemical analysis, the raw materials are compounded and mixed, the resulting mixture is charged into a line-frequency induction furnace for smelting, and an alloy wire stock is produced by upward casting, wherein the temperature during casting is gradually increased from a preheating temperature of 60 C. to a maximum temperature of 679 C.; step (2): the manufactured alloy wire stock is scalped followed by cold rolling and softening annealing to manufacture a rod stock having a specification of 7-9.8 mm; step (3): the obtained rod stock is subjected to plastic stretching of different passes to manufacture a 0.88-1.65 mm base core which is then degreased, acid-pickled and rinsed with water to remove external impurities; step (4): electrodeposition is performed on the base core by chemical plating, spray coating or hot dip plating to obtain a composite stock having a zinc oxide layer deposited on the surface thereof; step (5): the composite stock is subjected to a stretching-annealing process to obtain a pre-finished wire stock having a conforming size, wherein the stretching speed is 800-2800 m/min, the annealing voltage is 27-121 V and the annealing current is 13-43 A; step (6): the obtained pre-finished wire stock is subjected to surface treatment, zinc is melted at a temperature of 230-520 C. by an internal hot air flow, an irregular shape is formed on the surface of the core material by surface treatment, and meanwhile the temperature is gradually increased to form a composite plating from copper and zinc, thus finally obtaining an electrode wire product; and step (7): the electrode wire is taken up, qualified through quality inspection, then packaged and transported.

4. The method for manufacturing the electrode wire for electro-discharge machining according to claim 3, wherein the softening annealing is carried out by a two-stage annealing method, in which the first stage is a low-temperature annealing stage, the temperature is 49-267 C. and the holding time is 1.7-23 h; and the second stage is a high-temperature annealing stage, the temperature is 267.2-766 C. and the holding time is 2.3-33 h.

5. The method for manufacturing the electrode wire for electro-discharge machining according to claim 4, wherein the annealing distance of the first stage is 0.98-3.78 m and the annealing distance of the second stage is 4.12-11 m; and the annealing speed of the two stages is 7-570 m/min.

6. The method for manufacturing the electrode wire for electro-discharge machining according to claim 3, wherein the rod stock is subjected to heat treatment at a temperature of 53-600 C. for 1-8.8 h prior to the plastic stretching.

7. The method for manufacturing the electrode wire for electro-discharge machining according to claim 3, wherein in the surface treatment, the pre-finished wire stock is heated in a heating furnace which is provided with a conductive coil surrounding a closed pipeline, the conductive coil is supplied with power while heating is performed, and the power source supplies an alternating voltage.

8. The method for manufacturing the electrode wire for electro-discharge machining according to claim 7, wherein rolling is carried out by a roller simultaneously with heating to perform surface treatment on the core material such that the oxide layer is crystallized to crack.

9. The method for manufacturing the electrode wire for electro-discharge machining according to claim 7, wherein dry sandblasting is carried out simultaneously with heating, and a sand material is blasted onto the pre-finished wire stock such that the surface is eroded to crack.

10. The method for manufacturing the electrode wire for electro-discharge machining according to claim 9, wherein the dry sandblasting is used to accelerate the blasting of the sand material with compressed air as power by a pneumatic sand blasting device, or to blast the sand material with a centrifugal force by a hoist and a high-speed turntable.

11. A method for manufacturing an electrode wire for electro-discharge machining, wherein the electrode wire comprises a core material and a surface metal layer, and a transition layer is arranged between the core material and the surface metal layer, wherein the core material comprises a brass alloy as a main component and a balance amount of zinc and inevitable impurities; the surface metal layer comprises zinc oxide as a main component and a balance amount of copper and inevitable impurities, a transition layer is arranged between the core material and the surface metal layer, the transition layer comprises a copper-zinc alloy as a main component, and irregular cracks are distributed on the zinc oxide layer; the core material has a diameter of 0.65-1.48 mm, the surface metal layer has a thickness of 0.45-10.23 m, the maximum thickness of the cracks is less than or equal to 4.5 m, and the maximum spacing of the cracks is 17 m; the content of the brass alloy is 48-72 wt % and the impurity content is less than or equal to 0.38 wt % in the core material; and the content of the zinc oxide is 65-87 wt % and the balance content is less than or equal to 0.15 wt % in the surface metal layer; and the method for manufacturing the electrode wire for electro-discharge machining comprises the following steps: step (1): after raw materials containing copper and zinc are qualified by chemical analysis, the raw materials are compounded and mixed, the resulting mixture is charged into a line-frequency induction furnace for smelting, and an alloy wire stock is produced by upward casting, wherein the temperature during casting is gradually increased from a preheating temperature of 60 C. to a maximum temperature of 679 C.; step (2): the manufactured alloy wire stock is scalped followed by cold rolling and softening annealing to manufacture a rod stock having a specification of 7-9.8 mm; step (3): the obtained rod stock is subjected to plastic stretching of different passes to manufacture a 0.88-1.65 mm base core which is then degreased, acid-pickled and rinsed with water to remove external impurities; step (4): electrodeposition is performed on the base core by chemical plating, spray coating or hot dip plating to obtain a composite stock having a zinc oxide layer deposited on the surface thereof; step (5): the composite stock is subjected to a stretching-annealing process to obtain a pre-finished wire stock having a conforming size, wherein the stretching speed is 800-2800 m/min, the annealing voltage is 27-121 V and the annealing current is 13-43 A; step (6): the obtained pre-finished wire stock is subjected to surface treatment, zinc is melted at a temperature of 230-520 C. by an internal hot air flow, an irregular shape is formed on the surface of the core material by surface treatment, and meanwhile the temperature is gradually increased to form a composite plating from copper and zinc, thus finally obtaining an electrode wire product; and step (7): the electrode wire is taken up, qualified through quality inspection, then packaged and transported.

12. The method for manufacturing the electrode wire for electro-discharge machining according to claim 11, wherein the softening annealing is carried out by a two-stage annealing method, in which the first stage is a low-temperature annealing stage, the temperature is 49-267 C. and the holding time is 1.7-23 h; and the second stage is a high-temperature annealing stage, the temperature is 267.2-766 C. and the holding time is 2.3-33 h.

13. The method for manufacturing the electrode wire for electro-discharge machining according to claim 12, wherein the annealing distance of the first stage is 0.98-3.78 m and the annealing distance of the second stage is 4.12-11 m; and the annealing speed of the two stages is 7-570 m/min.

14. The method for manufacturing the electrode wire for electro-discharge machining according to claim 11, wherein the rod stock is subjected to heat treatment at a temperature of 53-600 C. for 1-8.8 h prior to the plastic stretching.

15. The method for manufacturing the electrode wire for electro-discharge machining according to claim 11, wherein in the surface treatment, the pre-finished wire stock is heated in a heating furnace which is provided with a conductive coil surrounding a closed pipeline, the conductive coil is supplied with power while heating is performed, and the power source supplies an alternating voltage.

16. The method for manufacturing the electrode wire for electro-discharge machining according to claim 15, wherein rolling is carried out by a roller simultaneously with heating to perform surface treatment on the core material such that the oxide layer is crystallized to crack.

17. The method for manufacturing the electrode wire for electro-discharge machining according to claim 15, wherein dry sandblasting is carried out simultaneously with heating, and a sand material is blasted onto the pre-finished wire stock such that the surface is eroded to crack.

18. The method for manufacturing the electrode wire for electro-discharge machining according to claim 17, wherein the dry sandblasting is used to accelerate the blasting of the sand material with compressed air as power by a pneumatic sand blasting device, or to blast the sand material with a centrifugal force by a hoist and a high-speed turntable.

Description

DETAILED DESCRIPTION OF THE INVENTION

Embodiment 1

[0027] An electrode wire for electro-discharge machining comprises a core material and a surface metal layer, a transition layer being arranged between the core material and the surface metal layer, wherein the core material comprises a brass alloy as a main component and a balance amount of zinc and inevitable impurities; and the surface metal layer comprises zinc oxide and a balance amount of copper and inevitable impurities, a transition layer is arranged between the core material and the surface metal layer, the transition layer comprises a copper-zinc alloy as a main component, and irregular cracks are distributed on the zinc oxide layer.

[0028] A method for manufacturing the electrode wire specifically comprises the following steps:

[0029] step (1): raw materials such as copper, zinc, phosphorus, magnesium, calcium, aluminum and rare earth are compounded in a certain ratio according to the alloy composition, wherein the specific weight in this embodiment is as follows: 45.430 kg of Cu, 30.250 kg of Zn, 0.605 kg of P, 0.076 kg of Mg, 0.040 kg of Ca, 3.010 kg of Al, 0.025 kg of La and 0.010 kg of Zr; after the raw materials are qualified by chemical analysis, the formulated mixture is charged into a line-frequency induction furnace for smelting, wherein the melting temperature is set to 1180 C. and the holding time is 30 min; and then an alloy wire stock is produced by upward casting, wherein the temperature during casting is gradually increased from a preheating temperature of 60 C. to a maximum temperature of 679 C.;

[0030] step (2): the manufactured alloy wire stock is scalped followed by cold rolling and softening annealing to manufacture a rod stock having a specification of 7 mm, wherein the softening annealing is carried out by a two-stage annealing method, in which the first stage is a low-temperature annealing stage, the temperature is 49-267 C., and the holding time is 10 h after 267 C. is reached; the second stage is a high-temperature annealing stage, the temperature is 267.2-766 C., and the holding time is 8 h after 766 C. is reached; the annealing distance of the first stage is 0.98 m and the annealing distance of the second stage is 4.12 m; and the annealing speed of the two stages is 310 m/min;

[0031] step (3): the obtained rod stock is subjected to plastic stretching of different passes to manufacture a 0.88 mm base core which is then degreased, acid-pickled and rinsed with water to remove external impurities, wherein the rod stock is subjected to heat treatment at a temperature of 53-600 C. for 1.5 h prior to the plastic stretching;

[0032] step (4): electrodeposition is performed on the base core by chemical plating, spray coating or hot dip plating to obtain a composite stock having a zinc oxide layer deposited on the surface thereof;

[0033] step (5): the composite stock is subjected to a stretching-annealing process to obtain a pre-finished wire stock having a conforming size, wherein the stretching-annealing process is carried out by annealing the composite stock with current in a stretching line, the stretching speed is 800-2800 m/min, the annealing voltage is 27-121 V, the annealing current is 13-43 A, and the annealing voltage and current are adjusted according to the desired annealing process;

[0034] step (6): the obtained pre-finished wire stock is subjected to surface treatment, during which the pre-finished wire stock is heated in a heating furnace which is provided with a conductive coil surrounding a closed pipeline, the conductive coil is supplied with power while heating is performed, and the power source supplies an alternating voltage; zinc is melted at a temperature of 230-520 C. by an internal hot air flow, and rolling is simultaneously carried out by a roller to perform surface treatment on the core material such that the oxide layer is crystallized to crack; and meanwhile the temperature is gradually increased to form a composite plating from copper and zinc, which is then subjected to stress-relief annealing at 180 C. for 2 s, thus finally obtaining an electrode wire product; and

[0035] step (7): the electrode wire is taken up, qualified through quality inspection, then packaged and transported.

[0036] The electrode wire product obtained by the above manufacturing method has the following parameters:

[0037] the core material has a diameter of 0.65 mm, the surface metal layer has a thickness of 0.55 m, the maximum thickness of the cracks is 1.5 m, and the maximum spacing of the cracks is 17 m; the content of the brass alloy is 48 wt % and the impurity content is less than or equal to 0.38 wt % in the core material; and the content of the zinc oxide is 77 wt % and the balance content is less than or equal to 0.15 wt % in the surface metal layer.

Embodiment 2

[0038] An electrode wire for electro-discharge machining comprises a core material and a surface metal layer, a transition layer being arranged between the core material and the surface metal layer, wherein the core material comprises a brass alloy as a main component and a balance amount of zinc and inevitable impurities; and the surface metal layer comprises zinc oxide and a balance amount of copper and inevitable impurities, a transition layer is arranged between the core material and the surface metal layer, the transition layer comprises a copper-zinc alloy as a main component, and irregular cracks are distributed on the zinc oxide layer.

[0039] A method for manufacturing the electrode wire specifically comprises the following steps:

[0040] step (1): raw materials such as copper, zinc, phosphorus, magnesium, calcium, aluminum and rare earth are compounded in a certain ratio according to the alloy composition, wherein the specific weight in this embodiment is as follows: 46.530 kg of Cu, 31.780 kg of Zn, 0.503 kg of P, 0.095 kg of Mg, 0.060 kg of Ca, 2.097 kg of Al, 0.035 kg of La and 0.020 kg of Zr; after the raw materials are qualified by chemical analysis, the formulated mixture is charged into a line-frequency induction furnace for smelting, wherein the melting temperature is set to 1180 C. and the holding time is 30 min; and then an alloy wire stock is produced by upward casting, wherein the temperature during casting is gradually increased from a preheating temperature of 60 C. to a maximum temperature of 679 C.;

[0041] step (2): the manufactured alloy wire stock is scalped followed by cold rolling and softening annealing to manufacture a rod stock having a specification of 9.8 mm, wherein the softening annealing is carried out by a two-stage annealing method, in which the first stage is a low-temperature annealing stage, the temperature is 49-267 C. and the holding time is 23 h; the second stage is a high-temperature annealing stage, the temperature is 267.2-766 C. and the holding time is 33 h; the annealing distance of the first stage is 3.78 m and the annealing distance of the second stage is 11 m; and the annealing speed of the two stages is 570 m/min;

[0042] step (3): the obtained rod stock is subjected to plastic stretching of different passes to manufacture a 1.65 mm base core which is then degreased, acid-pickled and rinsed with water to remove external impurities, wherein the rod stock is subjected to heat treatment at a temperature of 53-600 C. for 8.8 h prior to the plastic stretching;

[0043] step (4): electrodeposition is performed on the base core by chemical plating, spray coating or hot dip plating to obtain a composite stock having a zinc oxide layer deposited on the surface thereof;

[0044] step (5): the composite stock is subjected to a stretching-annealing process to obtain a pre-finished wire stock having a conforming size, wherein the stretching-annealing process is carried out by annealing the composite stock with current in a stretching line, the stretching speed is 800-2800 m/min, the annealing voltage is 27-121 V, the annealing current is 13-43 A, and the annealing voltage and current are adjusted according to the desired annealing process;

[0045] step (6): the obtained pre-finished wire stock is subjected to surface treatment, during which the pre-finished wire stock is heated in a heating furnace which is provided with a conductive coil surrounding a closed pipeline, the conductive coil is supplied with power while heating is performed, and the power source supplies an alternating voltage; zinc is melted at a temperature of 230-520 C. by an internal hot air flow, the blasting of a sand material is accelerated with compressed air as power by a pneumatic sand blasting device, or the sand material is blasted with a centrifugal force by a hoist and a high-speed turntable, and the sand material is blasted onto the pre-finished wire stock such that the surface is eroded to crack; and meanwhile the temperature is gradually increased to form a composite plating from copper and zinc, which is then subjected to stress-relief annealing at 180 C. for 2 s, thus finally obtaining an electrode wire product; and

[0046] step (7): the electrode wire is taken up, qualified through quality inspection, then packaged and transported.

[0047] The electrode wire product obtained by the above manufacturing method has the following parameters:

[0048] the core material has a diameter of 1.48 mm, the surface metal layer has a thickness of 10.23 m, the maximum thickness of the cracks is 4.5 m, and the maximum spacing of the cracks is 17 m; the content of the brass alloy is 72 wt % and the impurity content is less than or equal to 0.38 wt % in the core material; and the content of the zinc oxide is 87 wt % and the balance content is less than or equal to 0.15 wt % in the surface metal layer.

Embodiment 3

[0049] An electrode wire for electro-discharge machining comprises a core material and a surface metal layer, a transition layer being arranged between the core material and the surface metal layer, wherein the core material comprises a brass alloy as a main component and a balance amount of zinc and inevitable impurities; and the surface metal layer comprises zinc oxide and a balance amount of copper and inevitable impurities, a transition layer is arranged between the core material and the surface metal layer, the transition layer comprises a copper-zinc alloy as a main component, and irregular cracks are distributed on the zinc oxide layer.

[0050] A method for manufacturing the electrode wire specifically comprises the following steps:

[0051] step (1): raw materials such as copper, zinc, phosphorus, magnesium, calcium, aluminum and rare earth are compounded in a certain ratio according to the alloy composition; after the raw materials are qualified by chemical analysis, the formulated mixture is charged into a line-frequency induction furnace for smelting, wherein the melting temperature is set to 1180 C. and the holding time is 30 min; and then an alloy wire stock is produced by upward casting, wherein the temperature during casting is gradually increased from a preheating temperature of 60 C. to a maximum temperature of 679 C.;

[0052] step (2): the manufactured alloy wire stock is scalped followed by cold rolling and softening annealing to manufacture a rod stock having a specification of 7.7 mm, wherein the softening annealing is carried out by a two-stage annealing method, in which the first stage is a low-temperature annealing stage, the temperature is 49-267 C. and the holding time is 17 h; the second stage is a high-temperature annealing stage, the temperature is 267.2-766 C. and the holding time is 20 h; the annealing distance of the first stage is 1.96 m and the annealing distance of the second stage is 5.33 m; and the annealing speed of the two stages is 450 m/min;

[0053] step (3): the obtained rod stock is subjected to plastic stretching of different passes to manufacture a 1.21 mm base core which is then degreased, acid-pickled and rinsed with water to remove external impurities, wherein the rod stock is subjected to heat treatment at a temperature of 53-600 C. for 3.2 h prior to the plastic stretching;

[0054] step (4): electrodeposition is performed on the base core by chemical plating, spray coating or hot dip plating to obtain a composite stock having a zinc oxide layer deposited on the surface thereof;

[0055] step (5): the composite stock is subjected to a stretching-annealing process to obtain a pre-finished wire stock having a conforming size, wherein the stretching-annealing process is carried out by annealing the composite stock with current in a stretching line, the stretching speed is 800-2800 m/min, the annealing voltage is 27-121 V, the annealing current is 13-43 A, and the annealing voltage and current are adjusted according to the desired annealing process;

[0056] step (6): the obtained pre-finished wire stock is subjected to surface treatment, during which the pre-finished wire stock is heated in a heating furnace which is provided with a conductive coil surrounding a closed pipeline, the conductive coil is supplied with power while heating is performed, and the power source supplies an alternating voltage; zinc is melted at a temperature of 230-520 C. by an internal hot air flow, dry sandblasting is simultaneously carried out in which the blasting of a sand material is accelerated with compressed air as power by a pneumatic sand blasting device, or the sand material is blasted with a centrifugal force by a hoist and a high-speed turntable, and the sand material is blasted onto the pre-finished wire stock such that the surface is eroded to crack; and meanwhile the temperature is gradually increased to form a composite plating from copper and zinc, which is then subjected to stress-relief annealing at 180 C. for 2 s, thus finally obtaining an electrode wire product; and

[0057] step (7): the electrode wire is taken up, qualified through quality inspection, then packaged and transported.

[0058] The electrode wire product obtained by the above manufacturing method has the following parameters:

[0059] the core material has a diameter of 0.86 mm, the surface metal layer has a thickness of 2.8 m, the maximum thickness of the cracks is 2.5 m, and the maximum spacing of the cracks is 17 m; the content of the brass alloy is 55 wt % and the impurity content is less than or equal to 0.38 wt % in the core material; and the content of the zinc oxide is 67 wt % and the balance content is less than or equal to 0.15 wt % in the surface metal layer.

Embodiment 4

[0060] An electrode wire for electro-discharge machining comprises a core material and a surface metal layer, a transition layer being arranged between the core material and the surface metal layer, wherein the core material comprises a brass alloy as a main component and a balance amount of zinc and inevitable impurities; and the surface metal layer comprises zinc oxide and a balance amount of copper and inevitable impurities, a transition layer is arranged between the core material and the surface metal layer, the transition layer comprises a copper-zinc alloy as a main component, and irregular cracks are distributed on the zinc oxide layer.

[0061] A method for manufacturing the electrode wire specifically comprises the following steps:

[0062] step (1): raw materials such as copper, zinc, phosphorus, magnesium, calcium, aluminum and rare earth are compounded in a certain ratio according to the alloy composition; after the raw materials are qualified by chemical analysis, the formulated mixture is charged into a line-frequency induction furnace for smelting, wherein the melting temperature is set to 1180 C. and the holding time is 30 min; and then an alloy wire stock is produced by upward casting, wherein the temperature during casting is gradually increased from a preheating temperature of 60 C. to a maximum temperature of 679 C.;

[0063] step (2): the manufactured alloy wire stock is scalped followed by cold rolling and softening annealing to manufacture a rod stock having a specification of 7.5 mm, wherein the softening annealing is carried out by a two-stage annealing method, in which the first stage is a low-temperature annealing stage, the temperature is 49-267 C. and the holding time is 15.5 h; the second stage is a high-temperature annealing stage, the temperature is 267.2-766 C. and the holding time is 20.3 h; the annealing distance of the first stage is 2.35 m and the annealing distance of the second stage is 7.78 m; and the annealing speed of the two stages is 450 m/min;

[0064] step (3): the obtained rod stock is subjected to plastic stretching of different passes to manufacture a 1.45 mm base core which is then degreased, acid-pickled and rinsed with water to remove external impurities, wherein the rod stock is subjected to heat treatment at a temperature of 53-600 C. for 4.8 h prior to the plastic stretching;

[0065] step (4): electrodeposition is performed on the base core by chemical plating, spray coating or hot dip plating to obtain a composite stock having a zinc oxide layer deposited on the surface thereof;

[0066] step (5): the composite stock is subjected to a stretching-annealing process to obtain a pre-finished wire stock having a conforming size, wherein the stretching-annealing process is carried out by annealing the composite stock with current in a stretching line, the stretching speed is 800-2800 m/min, the annealing voltage is 27-121 V, the annealing current is 13-43 A, and the annealing voltage and current are adjusted according to the desired annealing process;

[0067] step (6): the obtained pre-finished wire stock is subjected to surface treatment, during which the pre-finished wire stock is heated in a heating furnace which is provided with a conductive coil surrounding a closed pipeline, the conductive coil is supplied with power while heating is performed, and the power source supplies an alternating voltage; zinc is melted at a temperature of 230-520 C. by an internal hot air flow, and rolling is simultaneously carried out by a roller to perform surface treatment on the core material such that the oxide layer is crystallized to crack; and meanwhile the temperature is gradually increased to form a composite plating from copper and zinc, which is then subjected to stress-relief annealing at 180 C. for 2 s, thus finally obtaining an electrode wire product; and

[0068] step (7): the electrode wire is taken up, qualified through quality inspection, then packaged and transported.

[0069] The electrode wire product obtained by the above manufacturing method has the following parameters:

[0070] the core material has a diameter of 0.96 mm, the surface metal layer has a thickness of 4.3 m, the maximum thickness of the cracks is 4.1 m, and the maximum spacing of the cracks is 17 m; the content of the brass alloy is 61 wt % and the impurity content is less than or equal to 0.38 wt % in the core material; and the content of the zinc oxide is 65 wt % and the balance content is less than or equal to 0.15 wt % in the surface metal layer.

Embodiment 5

[0071] An electrode wire for electro-discharge machining comprises a core material and a surface metal layer, a transition layer being arranged between the core material and the surface metal layer, wherein the core material comprises a brass alloy as a main component and a balance amount of zinc and inevitable impurities; and the surface metal layer comprises zinc oxide and a balance amount of copper and inevitable impurities, a transition layer is arranged between the core material and the surface metal layer, the transition layer comprises a copper-zinc alloy as a main component, and irregular cracks are distributed on the zinc oxide layer.

[0072] A method for manufacturing the electrode wire specifically comprises the following steps:

[0073] step (1): raw materials such as copper, zinc, phosphorus, magnesium, calcium, aluminum and rare earth are compounded in a certain ratio according to the alloy composition; after the raw materials are qualified by chemical analysis, the formulated mixture is charged into a line-frequency induction furnace for smelting, wherein the melting temperature is set to 1180 C. and the holding time is 30 min; and then an alloy wire stock is produced by upward casting, wherein the temperature during casting is gradually increased from a preheating temperature of 60 C. to a maximum temperature of 679 C.;

[0074] step (2): the manufactured alloy wire stock is scalped followed by cold rolling and softening annealing to manufacture a rod stock having a specification of 8.0 mm, wherein the softening annealing is carried out by a two-stage annealing method, in which the first stage is a low-temperature annealing stage, the temperature is 49-267 C. and the holding time is 14 h; the second stage is a high-temperature annealing stage, the temperature is 267.2-766 C. and the holding time is 19 h; the annealing distance of the first stage is 2.50 m and the annealing distance of the second stage is 7.50 m; and the annealing speed of the two stages is 500 m/min;

[0075] step (3): the obtained rod stock is subjected to plastic stretching of different passes to manufacture a 1.35 mm base core which is then degreased, acid-pickled and rinsed with water to remove external impurities, wherein the rod stock is subjected to heat treatment at a temperature of 53-600 C. for 1-8.8 h prior to the plastic stretching;

[0076] step (4): electrodeposition is performed on the base core by chemical plating, spray coating or hot dip plating to obtain a composite stock having a zinc oxide layer deposited on the surface thereof;

[0077] step (5): the composite stock is subjected to a stretching-annealing process to obtain a pre-finished wire stock having a conforming size, wherein the stretching-annealing process is carried out by annealing the composite stock with current in a stretching line, the stretching speed is 800-2800 m/min, the annealing voltage is 27-121 V, the annealing current is 13-43 A, and the annealing voltage and current are adjusted according to the desired annealing process;

[0078] step (6): the obtained pre-finished wire stock is subjected to surface treatment, during which the pre-finished wire stock is heated in a heating furnace which is provided with a conductive coil surrounding a closed pipeline, the conductive coil is supplied with power while heating is performed, and the power source supplies an alternating voltage; zinc is melted at a temperature of 230-520 C. by an internal hot air flow, and an irregular shape is formed on the surface of the core material by surface treatment; and meanwhile the temperature is gradually increased to form a composite plating from copper and zinc, which is then subjected to stress-relief annealing at 180 C. for 2 s, thus finally obtaining an electrode wire product; and

[0079] step (7): the electrode wire is taken up, qualified through quality inspection, then packaged and transported.

[0080] Optionally, rolling is carried out by a roller simultaneously with heating to perform surface treatment on the core material such that the oxide layer is crystallized to crack.

[0081] Optionally, dry sandblasting is carried out simultaneously with heating, wherein the blasting of a sand material is accelerated with compressed air as power by a pneumatic sand blasting device, or the sand material is blasted with a centrifugal force by a hoist and a high-speed turntable, and the sand material is blasted onto the pre-finished wire stock such that the surface is eroded to crack.

[0082] The electrode wire product obtained by the above manufacturing method has the following parameters:

[0083] the core material has a diameter of 1.01 mm, the surface metal layer has a thickness of 5.2 m, the maximum thickness of the cracks is 4.5 m, and the maximum spacing of the cracks is 17 m; the content of the brass alloy is 61 wt % and the impurity content is less than or equal to 0.38 wt % in the core material; and the content of the zinc oxide is 71 wt % and the balance content is less than or equal to 0.15 wt % in the surface metal layer.

[0084] The thickness and zinc content of the surface metal layers and the thickness of the cracks of the electrode wires for electro-discharge machining obtained by the manufacturing methods of the above embodiments of the invention are listed as follows:

TABLE-US-00001 Diameter Thickness of Content of zinc Maximum of core surface metal oxide in surface thickness of material (mm) layer (m) layer (wt %) crack (m) Embodiment 0.12 0.55 77 1.5 1 Embodiment 1.48 10.23 87 4.5 2 Embodiment 0.86 2.8 67 2.5 3 Embodiment 0.96 4.3 65 4.1 4 Embodiment 1.01 5.2 71 3.3 5

[0085] The obtained electrode wires for electro-discharge machining are tested for their comprehensive mechanical properties on a universal electronic tensile tester under microcomputer-based automatic control and for their electrical conductivity using a Wheatstone bridge method. The prepared electrode wires are tested for their EDM performance using grade 45 steel as a workpiece, and their service performance is compared with that of a brass electrode wire on the market in the following table.

TABLE-US-00002 Electrical Tensile Roughness Damage conductivity strength Cutting of cut to (IACS %) (Mpa) speed surface/m cutter Brass 21 1030 1 0.37 Slight electrode wire Embodiment 21 980 1.13 0.34 Slight 1 Embodiment 22 990 1.1 0.36 Slight 2 Embodiment 22 1000 1.16 0.35 Slight 3 Embodiment 21.8 1020 1.16 0.33 Slight 4 Embodiment 22.3 1010 1.18 0.33 Slight 5

[0086] It can be seen from the above table that the electrode wire of the invention has improved electrical conductivity as compared with the ordinary brass electrode wire, and its surface roughness is slightly improved after cutting; its mechanical properties such as tensile strength are decreased as compared with those of the ordinary brass electrode wire, but still fall within the numerical range of the electrode wire in cutting application, and do not affect its use; the damage to a cutter is slight; in addition, its cutting speed is improved as compared with that of the ordinary brass wire, thus improving the efficiency of electro-discharge machining.

[0087] The preferred embodiments of the invention have been described above in detail. It should be understood that the ordinary persons skilled in the art can make many modifications and variations without inventive work according to the concept of the invention. Accordingly, any technical solution that can be obtained by those skilled in the art according to the concept of the invention through logic analysis and reasoning or limited experimentation based on the prior art should fall within the protection scope determined by the claims.