JPS6284924A - Electrode wire and its manufacture wire electric discharge machining - Google Patents

Abstract

PURPOSE:To improve machining speed and spark stability and prevent short circuit by constituting an electrode wire with 20-40% of Zn, 0.1-5.0% of one ore more ingredients from among Al, Ga, Cr and Mn, and the rest of Cu and inevitable impurities. CONSTITUTION:A special yellow steel wire constituted with 20-40% of Zn by weight, 0.1-5% of one or more ingredients from among Al, Ga, Mn and Cr by weight and the rest of Cu and inevitable impurities, during the wire drawing process, is energized and heated in a nonoxidizing atmosphere while running the wire at lest one pass. By making the energized heating through an energized heating device consisting of one ore more heating zones to meet condition, 10<=SIGMAIkVk/D<2>S; with Ik as current in each zone, Vk applied voltage, D wire diameter, and S running speed; machining speed can be improved due to formation of a high Zn concentration layer near the wire surface, spark can be stabilized due to formation of a high concentration metal oxide layer of the additive ingredients, and the prevension of short circuit becomes possible.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to wire electrical discharge machines (with regard to electrode wires used, the electrical discharge machinability is improved by adding special elements to brass alloys and the manufacturing method thereof). It is.

Wire electrical discharge machining is usually called wire electrical discharge machining. While running an electrode wire of 0.05 to 0.35 mm, a pulsed discharge is generated with machining fluid interposed between it and the workpiece, and the workpiece is melted by the discharge energy, and the machining fluid and electric wire, It removes molten material by instantaneous vaporization explosive force from the workpiece, etc., and is widely used in the production of workpieces with complex and precise shapes, such as press molds.

In this wire electric discharge machining, the surface condition of the workpiece is good,
Electric discharge machinability is required, such as stable discharge, less disconnection, and high machining speed.

[Conventional technology and its problems]

Conventionally, pure copper wire was used as the electrode wire for wire electrical discharge machining, but due to its low tensile strength, it was not possible to apply too much tension during electrical discharge machining, and it was not possible to suppress the vibration of the electrical wire. Therefore, the machining accuracy is poor (and the wire is easily broken), and furthermore, the electric discharge machinability of Cu itself is not sufficient (
However, there were various drawbacks such as slow processing speed. For this reason, high-strength wires for precision processing such as molybdenum wires and tungsten wires are used, and brass electrode wires such as 65/35 brass wires are widely used for general processing. Brass electrode wire has more than twice the tensile strength of pure copper wire, and the presence of Zn, an alloying component, improves the vaporization explosive force, which allows the molten part of the workpiece to be removed efficiently and increases the processing speed. It has the advantage of improving the process and reducing deposits on the workpiece.

However, in recent years, with the improvement of the power supply and table feeding mechanism of wire electric discharge machining equipment, and the realization of unmanned operation, attention has been paid to the running cost and machining quality of wire electric discharge machining, and the electric discharge to the electrode wire has become more important. Demand for improved workability is increasing. In particular, improving discharge stability is important for machining accuracy and realizing unmanned operation, and the currently available brass electrode wires are not necessarily sufficient, so improvements have been desired.

When using a metal with high vapor pressure, such as Zn in brass (Cu-Zn alloy), the molten part of the workpiece can be removed efficiently, increasing the machining speed, reducing machining running costs, and improving the finished surface condition. In addition, by providing a coating layer with a high electrical insulation voltage such as a metal oxide, the discharge becomes stable and short circuits are prevented ((), and the table feed controlled by the servo mechanism becomes smooth and the machining speed increases. The purpose of the present invention is to satisfy the above-mentioned needs by adding limited additive elements to the Cu-Zn alloy and using a limited manufacturing method.

[Structure of the invention and its effects]

The present invention provides Cu-Zn alloy with AI, Ga,
In the process of drawing a special brass alloy wire containing metals such as Mn and Cr, the Z0 element is diffused and fixed to the surface layer of the wire by thermal diffusion, resulting in a high concentration of Zn. oxides such as AI, Ga, Mn, Cr, etc., namely Al2O3°Ga2O3, MnO2, CrO3 (7
) layer to provide short-circuit-free discharge stability and a reduction in deposits on the workpiece, which in turn aims to improve the machining speed. In other words, by utilizing the phenomenon of Zn diffusion at high temperatures, a high concentration Zn layer is generated on the surface layer of the brass wire, and elements that easily form oxides on the surface and have good discharge stability, such as AI, Ga, and Mn, are used. , Cr
The electrical discharge machinability has been improved by adding .

That is, in the present invention, 20 to 40 wt% of Zn and AI, (
3a, Mn.

A total of 0.1 to 5 wt of one or more types of Cr
% (hereinafter, the wt% of the composition components is expressed in terms of weight) and the balance Cu
In the drawing process, a special brass wire containing unavoidable impurities is heated with electricity in a non-oxidizing atmosphere while running the wire at least once.

The conditions for the electrical heating are as follows: In an electrical heating device equipped with one or more heating zones, the electrical current of each heating zone is 1 k (ampere), the applied voltage is k (volts), the diameter of the wire is D (mm), Traveling speed S (mAn) 4
It is characterized by satisfying 10≦ΣIkV, /1)''S within a range not exceeding 5. When manufactured within this condition range, the element concentration distribution near the surface of the electrode wire is as shown in Figure 2. The formation of a high concentration Zn layer improves the machining speed, reduces deposits on the workpiece, and furthermore, the formation of a high concentration metal oxide layer makes it possible to realize stable discharge.

Here, AI, Ga, I'i4n, and Cr were selected as additive elements because they are metals that are easily oxidized and easily form oxides on the surface layer.
With Ni, oxide formation cannot be expected and the discharge becomes unstable, while with Sn and Ge, the dezincing phenomenon is promoted and Zn is formed on the surface.
This is because it has been discovered that a depleted zone is created, which reduces the machining speed.

Regarding the amount of Zn, setting Zn to 20 to 40
If the Zn content is less than 0-, the lack of Zn in the wire itself cannot be compensated for even by the manufacturing method of the present invention, and the normally used 6
This is because a processing speed higher than 5/35 brass wire cannot be achieved. If the ratio exceeds 40, the wire drawability for diameter reduction will be extremely reduced, resulting in inefficient operation.

The sum of one or more of AI, Ga, Mn, and Cr with a coefficient of 0.1 to 5.0 is 0.1
This is because when the ratio is less than 50, the effect of the added element is small and the electrical discharge machinability is not improved, and when it exceeds 50, the wire drawability is extremely reduced, resulting in inefficient operation.

In addition, electric heating is used because it can heat at high temperatures for a short time, whereas conventional heating furnaces require a lot of time to heat up and cool down, which is inefficient and at the same time promotes the dezincing phenomenon at high temperatures. This is because Furthermore, the electric heating conditions were set to 10≦ΣI■ys within the range of not exceeding 45, because if it is less than 10, a sufficiently high concentration Zn layer and metal oxide layer will not be formed and the electrical discharge machinability such as machining speed will not improve ( This is because if the value exceeds 45, lead removal progresses, the Zn concentration in the A part of Table 7j decreases, and the processing speed decreases.

[Implemented Shioiri]

Example (1) After melting Cu using a graphite crucible and a high-frequency melting furnace and adding Zn with the hot water surface covered with charcoal powder, AI,
(3a), Mn, and Cr were added to produce 16 types of ingots with compositions according to the present invention as shown in Table 1, N[L1 to Arashi 16.The ingots were 25 mm square and 3 in length.
00 mm, and the surface was milled by 2.5 mm per side, hot rolled to 8 mm l K, and drawn into a wire rod of 2.0 mm l by die drawing. Next, this wire rod 2 was drawn into a wire rod 5 of 0.9 mm l using a continuous wire drawing machine equipped with an electric heating device 4 as shown in Figure 1, and subjected to electric heating. A voltage is applied to the energization heating device 4 in the preheating zone 7 and the heating zone 8, and the applied voltage is the same in both zones, and the current value differs depending on the length of the wire 5, that is, the resistance value. Also, the heating zone 8 is the wire rod 5
It is filled with water vapor to prevent unnecessary oxidation.

Linear speed: 500 mzQ, 600mAtm + 90
Table 1 also shows the heating conditions when heating was performed with various applied voltages set at 0 m/7. Engineering here! is the preheating current, ■
2 is a heating current. The 0.9 mml wire that was subjected to high-temperature, short-time electrical heating in this manner had a bright luster characteristic of the oxide of the additive element.

Next, these 0.9 mm 96 wire rods were drawn to 0.2 mm diameter using another continuous wire drawing machine to obtain a Ti wire according to an embodiment of the present invention.

As a comparative example, three types of alloys whose compositional components are not according to the present invention (14, 15, and 16) were 0.2 mt.
A wire rod of nφ was made using the same manufacturing method as in the above example, and other three types (N1117, Ni118, i'
h19) was difficult to wire-draw and difficult to reach a diameter of 0°2 mm.

Furthermore, as another comparative example, although the composition is according to the present invention, the current heating is not according to the conditions of the present invention, that is, 20 and N112.
! l is current heating condition is 10 or less, tooth 21°Nh22 is 4
Four types of wires with a rating of 5 or higher were made into 0.2 mm l wire rods. Further, as Comparative Example No. 24, an attempt was made to make a brass wire with a large amount of Zn, but it was difficult to draw the wire due to the β phase.

Also, as a conventional example, 65, which is conventionally used as an electrode wire,
/35 brass wire and pure copper wire at 0.9 mm l at 400°C
After heating for 1 hour, the wires were drawn to 0.2 mm 96 to obtain conventional electric wires 25 and 26.

The electrode wire of 0.2 mm l formed as described above was installed in an electrical discharge machine, and a 30 mm thick 5KD-11 workpiece was machined under the electrical discharge machining conditions shown in Table 2. Cut in a straight line.

Table 2 Processing results are also listed in Table 1. The machining speed ratio in Table 1 is expressed as the ratio, taking the machining speed of 65/35 brass wire 25 as 100, and the discharge stability is the magnitude of the variation in machining speed,
Comprehensive evaluation of ease of short circuit, etc., rated good as Ol and Kazuki as △
, defects are indicated by an X.

According to the processing results in Table 1, the temperature 1 according to the embodiment of the present invention is
-NcL1'5 are both superior in machining speed and discharge stability compared to conventional examples Arashi 25 and Arashi 26. In contrast, Comparative Example 14. The machining speed of leak 15 is poor. This is because the Zn content is smaller than that according to the present invention, so even with the current heating according to the present invention, the Zn concentration in the surface layer part cannot be sufficiently high. is inferior.This is Z
This is because, although the amount of n was not small, the amount of one of the added elements was smaller than the amount according to the present invention, so the formation of metal oxide was insufficient. Late 17. 18 and 19 were difficult to draw, so they were not made into 0.2 mm wire rods. This is because the total number of added elements exceeded 5. I'1k
L20 and A26 are not excellent in both machining speed and discharge stability. This is because although the compositions of both were according to the present invention, the current heating conditions were below the range according to the present invention, so the current heating was insufficient and the diffusion and precipitation of oxides and Zn into the surface layer was insufficient. N121 and 22 are significantly inferior in both machining speed and discharge stability.

This is because the Zn removal phenomenon occurred due to excessive electrical heating.

The surface had turned into a red pot.

Example (2) Five types of wire rods having the composition according to the present invention (l'VkL1. 4. No. 8. No. 11
．． 25) was selected and drawn into a wire of 0.2 mm l using a continuous wire drawing machine equipped with an electrical heating device shown in FIG. 1, and heated under the electrical heating conditions according to the present invention. The 10 types of electrode wires (1 to 10 in Table 6) of Example (2) thus produced were subjected to the same electrical discharge machining experiment as in Example (1).

As a comparative example, the composition and the current heating at 0.9 m'l were both according to the present invention, but the current heating at 0.2 mm da was not according to the present invention (l'h11+I' in Table 3). h
12), and one in which the electrical heating at 0.2 mm l was according to the present invention, but the compositional components were not according to the present invention (Table 6, 13.l'%14), and the compositional components were according to the present invention. Depends on 0
．． The current heating at 9 mm l and 0.2 mm 96 are both not according to the present invention (box 15 in Table 6), and the composition component and the current heating at 0.2 mm l are according to the present invention but 0. , 0.2 mm l electrode wires of 6 types @ (numbers 11 to NCL16 in Table 6) that were not subjected to electrical heating at 9 mm l according to the present invention (Arashi 16 in Table 6) were made. A processing test was conducted according to the example.

Also, as a conventional example, the 657s 5 brass wire of Example (1) was heated to 500°C and heated by running it at a linear speed of 100 instant motion on a 3 m long pipe, and the same electric discharge machining test as in the example was conducted. .

The electrical discharge machining test results of the above examples, comparative examples, and conventional examples are also listed in Table 3. The linear speed during electrical heating is 800 mm.
The experiment was conducted under 6 conditions: 1000 town products and 1200 rrM-. According to Table 5, according to the composition according to the present invention and according to the conditions of electrical heating, 0.9 mm l during the manufacturing process.
The results obtained when the wire was run and heated with electricity at 0.2 mm l and 0.2 mm l (Example Arashi 1 to 10) showed a difference of ~1 in both machining speed and discharge stability compared to the conventional example 17. Are better. In other words, it is sufficient that at least one of the two electrical heating operations complies with the conditions according to the present invention. For example, No. 1 is 0.9 mm and 96 o'clock energization heating, and 0.2 mm and core 10 are 0.2 mm. Only the energization heating at 1 o'clock conforms to the conditions of the present invention, and the other conditions are outside the range of 10 or less. The current heating conditions are 0.9 mm l and 0.2 mm l.
It's not the sum of times.

For example, the sum of 2 times is 32.5 + 24.6 = 57.1, which is outside the condition, but the condition at the time is 62.
5 and the second 24 and 6 are within the conditions.

Comparative example No. 11 and N12 are 0.2 + nm 1 o'clock,
In the case of Example 16, since the electrical heating at the time of 0 and 9 mm 96 was excessive beyond the conditions, Zn removal occurred and both the machining speed and discharge stability were significantly reduced. That is, if the condition exceeds 45 and current heating is performed outside the range even once, the electrical discharge machining result will deteriorate even if other current heating conditions are within the range. However, if the value is less than 10, it may be made to be more than 10 by other electrical heating. Further, although Nl113 has good discharge stability, the machining speed is inferior to that of conventional example No. 17. This is because the amount of Zn in the composition is smaller than that according to the present invention. NcL14 and NQ15 have good discharge stability.The former is because the amount of added element to the brass was smaller than the amount according to the present invention, and the latter has electric heating conditions of 0.9 mmO, 0.2
This is because both times when using mmg were outside the conditions of the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an electrical heating device with continuous wire drawing capable of manufacturing electrode wires according to the present invention. Figure 2 shows the relationship between Cu and Zn depending on the depth from the surface of the electrode wire.
. FIG. 3 is a diagram showing changes in the concentration of each additive element. 1: Supply 2: Wire 6: Wire drawing machine 4: Current heating device 5: Wire
6: Sprayer 7: Preheating zone 8: Heating zone 9: Cooling zone [Effect] As described above, according to the present invention, the machining speed is increased by increasing the concentration of the surface layer of the electrode wire that substantially contributes to electrical discharge machining. The precipitation of oxides such as AI, Ga, Mn, and Cr on the surface enables stable discharge and prevention of short circuits, which can be efficiently produced on an industrial scale and greatly contributes to the wire electrical discharge machining industry. be. Figure 2

Claims (2)

[Claims] (1) Composition of Zn20-40wt%, Al, Ga
, Cr, and Mn, with a total of 0.1 of one or two or more of them.
An electrode wire for wire electrical discharge machining consisting of ~5.0 wt%, the remainder being Cu and unavoidable impurities. (2) In the manufacturing process of the wire rod having the above composition, while running the wire rod, ΣI_kV_k/D^2S is 4
A method for producing an electrode wire for wire electrical discharge machining, characterized by carrying out electrical heating at least once under the conditions of the following formula within a range not exceeding 5. 10≦(ΣI_kV_k)/D^2S However, I_k: Current flowing in each heating zone (ampere) V
＿k: Applied voltage (volts) in each heating zone D: Wire diameter (
mm) S: Linear speed (m/mm)