Electrode wire for wire electrical discharge machining and quality control method for electrode wire for wire electrical discharge machining

Abstract

To provide a long electrode wire for wire electric discharge machining having high quality over the whole length, and a quality control method of the electrode wire for wire electric discharge machining for obtaining the electrode wire for wire electric discharge machining.SOLUTION: The wire 2 for wire electric discharge machining has a length of 200km or more, a standard deviation of diameters in the longitudinal direction of 0.29 μm or less over the entire length, and a roundness of 1.0 μm or less.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electrode wire for wire electric discharge machining and a quality control method for the electrode wire for wire electric discharge machining. [Background technology]

[0002] Conventionally, a method for evaluating the quality of a wire electrode for wire electrical discharge machining based on the standard deviation of the diameter is known (see Patent Document 1). By using the evaluation method of Patent Document 1 to manufacture a wire electrode for wire electrical discharge machining that satisfies the evaluation criteria, a high-quality wire electrode for wire electrical discharge machining can be obtained. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-119020 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the dies used in drawing wire-cutting electrode wires for wire electrical discharge machining wear with continued use due to friction with the wire, which causes variations in the diameter and roundness of the wire-cutting electrode wires. As a result, it is difficult to ensure high quality for long wire-cutting electrode wires, for which the dies wear significantly from the start to the end of wire-drawing.

[0005] An object of the present invention is to provide a long wire electrode wire for wire electrical discharge machining that has high quality over its entire length, and a quality control method for obtaining the wire electrode wire for wire electrical discharge machining. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention provides an electrode wire for wire electric discharge machining, which is 200 km or longer in length, has a standard deviation of diameter in the longitudinal direction of 0.29 μm or less, and has a circularity of 1.0 μm or less over its entire length.

[0007] Furthermore, for the purpose of solving the above-mentioned problems, the present invention provides a quality control method for a wire electric discharge machining electrode wire, which comprises repeating a wiredrawing step of using a wiredrawing die to draw a wire electric discharge machining electrode wire to a length of 200 km or more, and a measuring step of measuring the standard deviation of diameter in the longitudinal direction and the roundness of a portion of the wiredrawing end side of the drawn wire electric discharge machining electrode wire, to derive a maximum number of times the dies can be used in the wiredrawing step that satisfies the conditions that the standard deviation of diameter is 0.29 μm or less and the roundness is 1.0 μm or less, and when the wiredrawing step is repeatedly performed after deriving the maximum number of times the wiredrawing die can be used, replacing the wiredrawing die with a new one when or before the maximum number of times the wiredrawing die has been used reaches the maximum number of times. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a long wire electric discharge machining electrode wire having high quality over its entire length, and a quality control method for wire electric discharge machining electrode wire for obtaining the wire electric discharge machining electrode wire. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of a wire electric discharge machine including a wire electric discharge machining electrode wire according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating the configuration of a wire drawing machine used to manufacture an electrode wire for wire electric discharge machining according to this embodiment of the present invention. [Figure 3] Fig. 3(a) is a perspective view showing a schematic diagram of how the diameter of a sample is measured, and Fig. 3(b) is a view showing a schematic diagram of how the roundness of a sample is measured, as viewed from the longitudinal direction of the sample. [Figure 4]FIG. 4 is a graph showing the relationship between the standard deviation of the diameter in the length direction of the wire electrode for wire electric discharge machining and the circularity. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Features of electrode wire for wire EDM) 1 is a perspective view showing a schematic configuration of a wire electric discharge machine 10 including a wire electric discharge machining electrode wire 1 according to an embodiment of the present invention. The Z direction shown in FIG. 1 is parallel to the longitudinal direction of the wire electric discharge machining electrode wire 1, and the X and Y directions are perpendicular to each other and are both perpendicular to the Z direction.

[0011] The wire electric discharge machine 10 has a replaceable consumable electrode wire 1 for wire electric discharge machining, and rolls 11 and 12 for securing the electrode wire 1 in a tensioned state so that it extends in the Z direction. The wire electric discharge machine 10 also has a table (not shown) that is movable in the X and Y directions, and a workpiece 13 for wire electric discharge machining is secured to this table. Typically, the Z direction is parallel to the vertical direction, and the X and Y directions are parallel to the horizontal direction. In FIG. 1, the roll 11 is positioned above the workpiece 13, and the roll 12 is positioned below the workpiece 13.

[0012] 1 shows a plate-shaped workpiece 13 with a start hole 14 formed through it from the top to the bottom, and a predetermined area machined from the start hole 14 by wire discharge. Although not shown, the workpiece 13 is immersed in a machining fluid. The machining fluid is a liquid with low conductivity, such as insulating oil or ion-exchanged water.

[0013] The wire electric discharge machining electrode wire 1 is a linear wire having a circular cross section in the radial direction, and is made of a conductive material such as brass. The workpiece 13 is also made of a conductive material.

[0014] The wire electric discharge machine 10 generates intermittent pulse discharges between the wire electric discharge machining electrode wire 1 and the workpiece 13, melting and removing the workpiece 13 through the thermal action and impact force that occur during this process. Here, the workpiece 13, which is fixed to the table, is moved in the X or Y direction to machine it into the desired shape. The wire electric discharge machining electrode wire 1 is fed in the Z direction as the rolls 11 and 12 rotate during the machining operation. This is to prevent a decrease in machining accuracy and breakage of the wire electric discharge machining electrode wire 1, which would otherwise be caused by wear of the wire electric discharge machining electrode wire 1 due to discharge.

[0015] The wire electric discharge machining electrode wire 1 is obtained by cutting a long wire electric discharge machining electrode wire 2 (described later) having a length of 200 km or more to a desired length. The wire electric discharge machining electrode wire 1 used in the wire electric discharge machine 10 is a finished product, and the wire electric discharge machining electrode wire 2 corresponds to an intermediate product in the manufacturing process.

[0016] The wire electric discharge machining electrode wire 2 has a weight and a length according to its diameter. Table 1 below shows an example of the relationship between the diameter, weight, and length of the wire electric discharge machining electrode wire 2.

[0017] [Table 1]

[0018] The wire electric discharge machining electrode wire 1 obtained by cutting the wire electric discharge machining electrode wire 2 has a mass of, for example, 5 kg, 10 kg, 20 kg, 50 kg, etc., and for example, if the diameter is 0.20 mm, the mass is 5 kg and the length is approximately 18.97 km.

[0019] The wire electric discharge machining electrode wire 2 is 200 km or longer and has high quality, with a standard deviation of diameter in the longitudinal direction of 0.29 μm or less and a roundness of 1.0 μm or less over its entire length. Because the wire electric discharge machining electrode wire 2 has high quality over its entire length, the occurrence of wire marks on the machined surface of the workpiece 13 can be suppressed regardless of which part of the wire electric discharge machining electrode wire 2 is used for wire electric discharge machining. The method for measuring the standard deviation of diameter and roundness of the wire electric discharge machining electrode wire 2 will be described later.

[0020] (Manufacturing electrode wires for wire electrical discharge machining) FIG. 2 is a schematic diagram illustrating the configuration of a wire drawing machine 20 used to manufacture the electrode wire 2 for wire electric discharge machining according to this embodiment of the present invention.

[0021] FIG. 2 shows the wire drawing machine 20 equipped with a wire drawing die 22 for drawing the wire electrical discharge machining electrode wire 2, a capstan 21 for transporting the wire electrical discharge machining electrode wire 2 to the wire drawing die 22, a dancer 25 which is a speed adjustment mechanism for the wire electrical discharge machining electrode wire 2, and a capstan 26 for pulling the wire electrical discharge machining electrode wire 2 from the wire drawing die 22 and transporting it.

[0022] The wire drawing machine 20 has a plurality of wire drawing dies arranged along the wire drawing direction. The wire drawing die 22 shown in Fig. 2 is the last of the plurality of wire drawing dies and is called a finish wire drawing die. A plurality of wire drawing dies called intermediate wire drawing dies are arranged in front of the wire drawing die 22 (to the left of the capstan 21 in Fig. 2). The further back the plurality of wire drawing dies are arranged, the smaller the diameter of the die hole on the outlet side, and the wire drawing die 22 arranged last has the smallest diameter on the outlet side of the die hole.

[0023] The multiple wiredrawing dies, including the wiredrawing die 22, are made of, for example, a metal plate having a die hole penetrating through the thickness direction. The diameter of the die hole gradually decreases from the front side to the back side of the wiredrawing die, so that the wire electric discharge machining electrode wire 2 fed from the front side of each wiredrawing die into the die hole is narrowed and elongated as it passes through the die hole. The diameter of the wire electric discharge machining electrode wire 2 after being drawn by the wiredrawing die 22, which is a finish wiredrawing die, is, for example, 0.1 mm or more and 0.3 mm or less.

[0024] Lubricating oil is supplied to each of the wire drawing dies to reduce friction with the wire electrical discharge machining electrode wire 2. This lubricating oil is removed from the surface of the wire electrical discharge machining electrode wire 2 as the wire electrical discharge machining electrode wire 2 passes through each of the wire drawing dies.

[0025] In the manufacturing process of the wire electrical discharge machining electrode wire 2, first, the wire electrical discharge machining electrode wire 2 before drawing is supplied to a wire drawing machine 20 from a roll (not shown) on which the wire electrical discharge machining electrode wire 2 is wound. Next, the wire electrical discharge machining electrode wire 2 is drawn by passing through a plurality of intermediate wire drawing dies. At this time, the wire electrical discharge machining electrode wire 2 is fed by a capstan installed between the plurality of intermediate wire drawing dies. Next, the wire electrical discharge machining electrode wire 2 is wound around a capstan 21 and then fed to a wire drawing die 22.

[0026] The wire electrical discharge machining electrode wire 2 drawn by the wire drawing die 22 is wound around the capstan 26 and transported. That is, the wire electrical discharge machining electrode wire 2 is pulled out of the wire drawing die 22 by the capstan 26. The capstans provided in the wire drawing machine 20, such as the capstan 21 and the capstan 26, are made of, for example, metal rolls. The wire electrical discharge machining electrode wire 2 wound around these capstans is transported by friction with the capstans that are driven to rotate.

[0027] Because the wire electric discharge machining electrode wire 2 is drawn thinner by passing through multiple wire drawing dies, the conveyance speed is faster after passing through the multiple wire drawing dies than before. To prevent abnormal elongation or breakage of the wire electric discharge machining electrode wire 2, a dancer 25, which is a speed adjustment mechanism for the wire electric discharge machining electrode wire 2, is provided after the capstan 26. The dancer 25 is composed of, for example, a roll 23 whose rotation axis is fixed and a roll 24 that moves up and down, and the wire electric discharge machining electrode wire 2 is wound multiple times around the rolls 23 and 24.

[0028] The wire electric discharge machining electrode wire 2, whose speed is adjusted by the dancer 25, is wound, for example, around a bobbin (roll, drum) 27. In this embodiment, a wire electric discharge machining electrode wire 2 having a length of 200 km or more is wound around one bobbin 27.

[0029] (Evaluation of electrode wires for wire electrical discharge machining) The following describes a method for measuring the standard deviation of diameter and roundness to evaluate the quality of the electrode wire 2 for wire electric discharge machining.

[0030] In measuring the standard deviation of the diameter of the wire electric discharge machining electrode wire 2, first, a portion of the end of the winding of the wire electric discharge machining electrode wire 2 wound around the bobbin 27, i.e., a portion of the end of the wire drawing (the last drawn portion), is taken and used as a measurement sample (hereinafter referred to as sample 100). This sample 100 has a length of, for example, several meters to several tens of meters.

[0031] The reason why a portion of the drawing end of the wire electric discharge machining electrode wire 2 is used as the measurement sample 100 is that this portion is drawn by the wire drawing die 22 in the most worn state and is the portion of lowest quality. In other words, if this sample 100 has high quality, the wire electric discharge machining electrode wire 2 will have high quality throughout its entire length.

[0032] As described above, wire electrical discharge machining is performed while feeding the wire electrical discharge machining electrode wire 1 obtained by cutting the wire electrical discharge machining electrode wire 2 in the Z direction. Therefore, the diameter of the sample 100 is measured while feeding the sample 100 in the Z direction using a traveling machine that imitates the wire electrical discharge machine 10. This traveling machine includes, for example, rolls 11 and 12 of the wire electrical discharge machine 10 that can feed the sample 100 in the Z direction by rotating.

[0033] FIG. 3(a) is a perspective view showing a schematic diagram of how the diameter D of the sample 100 is measured. A laser diameter measuring instrument 30 is installed between the rolls 11 and 12 of the traveling machine, and the diameter D of the measurement sample, which is fed at a constant speed, is continuously measured at a constant timing. The laser diameter measuring instrument 30 measures the diameter D of the sample 100 using a laser beam 33 that is scanned at high speed between a light transmitting unit 31 and a light receiving unit 32. This makes it possible to measure the diameter D at multiple points along the length of the sample 100.

[0034] Next, the standard deviation is calculated from the multiple diameters D of the measured samples 100, and it is determined whether the standard deviation is 0.29 μm or less, and whether it is 0.15 μm or less. If the standard deviation of the diameters D of the samples 100 is 0.29 μm or less, it can be said that the standard deviation of the diameters is 0.29 μm or less over the entire length of the wire electric discharge machining electrode wire 2. Similarly, if the standard deviation of the diameters D of the samples 100 is 0.15 μm or less, it can be said that the standard deviation of the diameters is 0.15 μm or less over the entire length of the wire electric discharge machining electrode wire 2.

[0035] The standard deviation is calculated using the following formula (1): where s is the standard deviation, n is the number of measured diameters D, and x i is the individual value of the measured diameter D, and the x with a bar on top is the average value of the measured diameter D.

[0036]

number

[0037] To ensure the reliability of the standard deviation and effectively suppress the occurrence of wire marks, it is preferable to measure the diameter at 50 or more locations per meter in the longitudinal direction of the sample 100. For example, the diameter of the measurement sample is measured at 800 locations per meter. More specifically, for example, using a sample 100 having a length of 15 m or more, the diameter D is measured at 4,000 locations within three different ranges of 5 m in length, the standard deviation of the three diameters D is calculated, and it is determined whether all of the standard deviations of the three diameters D are 0.29 μm or less and whether they are 0.15 μm or less.

[0038] The measurement of the roundness of the wire electric discharge machining electrode wire 2 is also carried out using the sample 100.

[0039] 3(b) is a view seen from the longitudinal direction of the sample 100, schematically illustrating how the roundness of the sample 100 is measured. In measuring the roundness, the diameter D is repeatedly measured using the laser outer diameter measuring instrument 30 while the sample 100 is rotated around a central axis parallel to the longitudinal direction.

[0040] The difference between the maximum and minimum values ​​of the measured diameter D is then calculated as the circularity, and it is determined whether the circularity is 1.0 μm or less, and whether it is 0.5 μm or less. If the circularity of sample 100 is 1.0 μm or less, it can be said that the circularity is 1.0 μm or less over the entire length of wire electrical discharge machining electrode wire 2. Similarly, if the circularity of sample 100 is 0.5 μm or less, it can be said that the circularity is 0.5 μm or less over the entire length of wire electrical discharge machining electrode wire 2.

[0041] As a result of extensive research, the inventors have found that when the standard deviation of the diameter in the length direction of the wire electrical discharge machining electrode wire 2 is 0.29 μm or less and the roundness is 1.0 μm or less, the occurrence of wire marks can be suppressed in wire electrical discharge machining under general usage conditions (e.g., 3rd cut, i.e., using a specific wire electrical discharge machining electrode wire three times for electrical discharge machining), and when the standard deviation of the diameter in the length direction of the wire electrical discharge machining electrode wire 2 is 0.15 μm or less and the roundness is 0.5 μm or less, the occurrence of wire marks can also be suppressed in wire electrical discharge machining under conditions in which wire marks are more likely to occur than general usage conditions (e.g., 4th cut or more, i.e., using a specific wire electrical discharge machining electrode wire four or more times for electrical discharge machining).

[0042] According to an embodiment of the present invention, by using the above-described evaluation method for wire electrical discharge machining electrode wire 2, a wire electrical discharge machining electrode wire 2 that satisfies the evaluation criteria, for example, "the standard deviation of the diameter in the longitudinal direction of the wire electrical discharge machining electrode wire 2 is 0.29 μm or less and the roundness is 1.0 μm or less," it is possible to obtain a high-quality wire electrical discharge machining electrode wire 2.

[0043] In order to manufacture a high-quality electrode wire 2 for wire electrical discharge machining that satisfies these conditions, it is necessary to replace the wire drawing die 22 at an appropriate time before wear progresses to the extent that the desired quality of the electrode wire 2 for wire electrical discharge machining can no longer be obtained.

[0044] For example, by repeatedly drawing the wire electric discharge machining electrode wire 2 and measuring the standard deviation of the diameter and roundness in the longitudinal direction of the wire electric discharge machining electrode wire 2 after drawing, the maximum number of times the die can be used in the wire drawing process that can ensure the desired quality can be determined, and the appropriate timing for replacing the wire drawing die 22 can be determined.

[0045] That is, according to the embodiment of the present invention, a quality control method for a wire electric discharge machining electrode wire (2) can be provided, which includes repeating a wiredrawing step of using a wiredrawing die (22) to draw a wire electric discharge machining electrode wire (2) to a length of 200 km or more and a measuring step of measuring the standard deviation of diameter in the longitudinal direction and the roundness of a portion of the wiredrawing end side of the drawn wire electric discharge machining electrode wire (2), thereby deriving a maximum number of times that the wiredrawing die (22) can be used in the wiredrawing step that satisfies the conditions that the standard deviation of diameter is 0.29 μm or less and the roundness is 1.0 μm or less, and replacing the wiredrawing die (22) with a new one when or before the number of times that the wiredrawing die (22) has been used reaches the maximum number of times that the wiredrawing die (22) has been used when the wiredrawing step is repeatedly performed after deriving the maximum number of times.

[0046] In addition, in the above-mentioned quality control method for the electrode wire 2 for wire electric discharge machining, in order to obtain a higher quality electrode wire 2 for wire electric discharge machining, the above conditions may be set to a standard deviation of the diameter of 0.15 μm or less and a circularity of 0.5 μm or less.

[0047] Fig. 4 is a graph showing the relationship between the standard deviation of the diameter in the length direction and the roundness of the wire electrode wire for wire electrical discharge machining 2. In Fig. 4, the diameter of sample 100 was measured at 4,000 locations within three different ranges of 5 m length, the standard deviations of the three diameters were calculated, and the maximum value of these was taken as the standard deviation of the diameter in the length direction of the wire electrode wire for wire electrical discharge machining 2. The roundness of the wire electrode wire for wire electrical discharge machining 2 was measured using a laser outer diameter measuring instrument with a wire rotation device (WSR-S610 manufactured by Celsa).

[0048] Fig. 4 shows that there is a linear correlation between the standard deviation of diameter and roundness, at least within the range shown in Fig. 4. The approximation line obtained by linear approximation of the distribution of plotted points shown in the graph of Fig. 4 is expressed as approximately s = 0.28c, where s [μm] is the standard deviation of diameter in the length direction of the wire electric discharge machining electrode wire 2 and c [μm] is the roundness. For example, as shown in Fig. 4, when the roundness is in the range of 0.2 μm or more and 1.0 μm or less (0.2≦c≦1.0), the values ​​of the standard deviation of diameter and roundness fall within the range shown by 0.28c − 0.08≦s ≦ 0.28c + 0.08.

[0049] (Effects of the embodiment) According to this embodiment of the present invention, it is possible to provide a long wire electrical discharge machining electrode wire 2 having high quality throughout its entire length, and a quality control method for the wire electrical discharge machining electrode wire 2 for obtaining the wire electrical discharge machining electrode wire 2.

[0050] The wire electric discharge machining electrode wire 2 according to this embodiment of the present invention has a length of 200 km or more, and by cutting it into desired lengths, for example, 10 to 190 km, multiple high-quality wire electric discharge machining electrode wires can be obtained.

[0051] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiments will be described by using the reference numerals and the like in the embodiments. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiments.

[0052] [1] An electrode wire for wire electric discharge machining (2) having a length of 200 km or more, a standard deviation of the diameter in the longitudinal direction of 0.29 μm or less, and a circularity of 1.0 μm or less over the entire length.

[0053] [2] The electrode wire (2) for wire electric discharge machining according to the above [1], wherein, when the standard deviation of the diameter in the length direction is s [μm] and the circularity is c [μm], the relationship of 0.28c-0.08≦s≦0.28c+0.08 (0.2≦c≦1.0) is satisfied.

[0054] [3] The electrode wire (2) for wire electric discharge machining according to [1] or [2] above, wherein the standard deviation of the diameter in the longitudinal direction is 0.15 μm or less and the circularity is 0.5 μm or less over the entire length.

[0055] [4] A quality control method for a wire electric discharge machining electrode wire (2), comprising: repeating a wire drawing step of drawing a wire electric discharge machining electrode wire (2) to a length of 200 km or more using a wire drawing die (22); and a measuring step of measuring a standard deviation of diameter in the longitudinal direction and roundness of a portion of the wire drawing end side of the drawn wire electric discharge machining electrode wire (2); deriving a maximum number of uses of the wire drawing die (22) in the wire drawing step that satisfies the conditions that the standard deviation of diameter is 0.29 μm or less and the roundness is 1.0 μm or less; and replacing the wire drawing die (22) with a new one when the number of uses of the wire drawing die (22) reaches or before the maximum number of uses is reached when the wire drawing step is repeatedly performed after deriving the maximum number of uses.

[0056] [5] The quality control method for the electrode wire (2) for wire electric discharge machining according to [4] above, wherein the conditions are that the standard deviation of the diameter is 0.15 μm or less and the roundness is 0.5 μm or less.

[0057] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and various modifications can be made without departing from the spirit of the invention. Furthermore, the above-described embodiments do not limit the scope of the invention according to the claims. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. [Explanation of symbols]

[0058] 1. Electrode wire for wire electric discharge machining 10. Wire Electrical Discharge Machine 20 Wire drawing machine 22 Wire drawing dies 100 samples

Claims

1. It is over 200 km long, The standard deviation of the diameter in the longitudinal direction is 0.29 μm or less and the circularity is 1.0 μm or less over the entire length. Electrode wire for wire electric discharge machining.

2. When the standard deviation of the diameter in the length direction is s [μm] and the circularity is c [μm], the relationship of 0.28c-0.08≦s≦0.28c+0.08 (0.2≦c≦1.0) is satisfied. The electrode wire for wire electric discharge machining according to claim 1.

3. The standard deviation of the diameter in the longitudinal direction is 0.15 μm or less and the circularity is 0.5 μm or less over the entire length. The electrode wire for wire electric discharge machining according to claim 1 or 2.

4. a wiredrawing step of drawing a wire electric discharge machining electrode wire to a length of 200 km or more using a wiredrawing die, and a measuring step of measuring a standard deviation of diameter in the length direction and roundness of a part of the drawn wire electric discharge machining electrode wire at a wiredrawing end side, to derive a maximum number of times the wiredrawing die can be used in the wiredrawing step that satisfies the conditions that the standard deviation of diameter is 0.29 μm or less and the roundness is 1.0 μm or less; When the wiredrawing step is repeatedly performed after the maximum number of uses has been calculated, the wiredrawing die is replaced with a new one when or before the number of uses of the wiredrawing die reaches the maximum number of uses. Quality control method for electrode wire for wire electrical discharge machining.

5. The conditions are that the standard deviation of the diameter is 0.15 μm or less and the circularity is 0.5 μm or less.

5. The method for quality control of the electrode wire for wire electric discharge machining according to claim 4.

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