Wire electric discharge machining method and wire electric discharge machine

Abstract

To provide a wire electric discharge machining method and a wire electric discharging machine which improves machining accuracy of wire electric discharge machining.SOLUTION: A wire electric discharging machine includes a first travelling mechanism 21a which performs primary working of a workpiece W by travelling a first electrode wire 24a for electric discharge machining along a first direction of the workpiece W and a second travelling mechanism 21b which performs secondary working of a primary worked part worked by using the electrode wire for first electric discharging by travelling a second electrode wire 24b for electric discharge machining along a second direction of the workpiece W that is the direction opposite to the first direction.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a wire electric discharge machining technique for machining a workpiece by electric discharge generated between an electric discharge machining electrode wire and the workpiece. [Background technology]

[0002] Wire electric discharge machining is a technology that uses a wire electrode, or electric discharge machining electrode wire (hereinafter also referred to as electrode wire), as a tool electrode to machine a workpiece into a desired shape. The workpiece is placed in a machining tank containing machining fluid, and an arc discharge is generated between the electrode wire and the workpiece in the insulating machining fluid. The workpiece is cut by partially wearing away the workpiece with the thermal energy from the discharge. To prevent breakage due to wear, the electrode wire is fed toward the workpiece by a traveling roller during machining, so that a new part of the electrode wire faces the workpiece.

[0003] Patent Document 1 discloses a wire electric discharge machine having a plurality of electrode wires, each capable of simultaneously machining a different area. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-142315 Summary of the Invention [Problem to be solved by the invention]

[0005] In wire electric discharge machines, the electrode wire typically travels in one direction along the workpiece from the machining start point on the top surface to the machining end point on the bottom surface, and wear of the electrode wire increases as the electrode wire travels toward the bottom surface of the workpiece. For this reason, the diameter of the electrode wire is thinner on the bottom surface than on the top surface. In wire electric discharge machines that move the electrode wire horizontally, the electrode wire travels along the workpiece from the machining start point on one side (left or right) to the machining end point on the other side (left or right), and the diameter of the electrode wire is thinner at the machining end point.

[0006] When the diameter of the electrode wire becomes thinner due to wear as it travels, the distance between the electrode wire and the workpiece increases, making it more difficult for the discharge energy to reach the workpiece. This causes differences in the amount of melting of the workpiece between the start and end of machining. This results in differences in machining dimensions between the top and bottom of the workpiece, i.e., the start and end of machining, resulting in reduced machining accuracy. To prevent these differences in machining dimensions, wire EDM machines tilt the electrode wire slightly to prevent the distance from the workpiece from changing even as the electrode wire wears. As such, the machining conditions for wire EDM machines include parameters for tilting the electrode wire, making the machining control of the machine complex.

[0007] An object of the present invention is to improve the machining accuracy of wire electric discharge machining. [Means for solving the problem]

[0008] The wire electric discharge machining method of the present invention is a wire electric discharge machining method for machining a workpiece using an electric discharge machining electrode wire, and includes a first machining step of primarily machining the workpiece by running a first electric discharge machining electrode wire along a first direction of the workpiece, and a second machining step of secondarily machining the primarily machined portion machined using the first electric discharge machining electrode wire by running a second electric discharge machining electrode wire along a second direction of the workpiece that is opposite to the first direction.

[0009] The wire electric discharge machine of the present invention is a wire electric discharge machine that machines a workpiece using an electric discharge machining electrode wire, and includes a first traveling mechanism that performs primary machining on the workpiece by running a first electric discharge machining electrode wire along a first direction of the workpiece, and a second traveling mechanism that performs secondary machining on the primary machined portion machined using the first electric discharge machining electrode wire by running a second electric discharge machining electrode wire along a second direction of the workpiece that is opposite to the first direction.

[0010] The wire electric discharge machine of the present invention is a wire electric discharge machine that machines a workpiece using an electric discharge machining electrode wire, and includes a traveling mechanism that primarily machines the workpiece by running the electric discharge machining electrode wire along a first direction of the workpiece, and secondarily machines the primarily machined portion machined by the primary machining by running the electric discharge machining electrode wire in a second direction of the workpiece that is opposite to the first direction, and a reversing mechanism that reverses the traveling mechanism from a position where the electric discharge machining electrode wire runs in the first direction to a position where the electric discharge machining electrode wire runs in the second direction after the primary machined portion has been machined. [Effects of the Invention]

[0011] The primary machined portion machined by a first electric discharge machining electrode wire running in a first direction relative to the workpiece is then secondarily machined by a second electric discharge machining electrode wire running in the opposite direction to the first electric discharge machining electrode wire, so that the secondary machined portion is machined to have approximately the same width throughout, thereby improving the machining accuracy of wire electric discharge machining. [Brief explanation of the drawings]

[0012] [Figure 1A] 1 is a schematic diagram showing a wire electric discharge machine according to an embodiment; [Figure 1B] 1B is a schematic diagram showing the wire electric discharge machine of FIG. 1A in a state of a first machining step. [Figure 1C] 1B is a schematic diagram showing the wire electric discharge machine of FIG. 1A in a state of a second machining step. FIG. [Figure 2]FIG. 2 is a block diagram showing a control circuit of the wire electric discharge machine. [Figure 3A] FIG. 3 is a perspective view showing a workpiece and a first electric discharge machining electrode wire in a first machining step. [Figure 3B] FIG. 10 is a perspective view showing a workpiece and a second electric discharge machining electrode wire in a second machining step. [Figure 4A] FIG. 2 is a perspective view showing a wear state of an electric discharge machining electrode wire and a primarily machined portion of a workpiece in a first machining step. [Figure 4B] FIG. 10 is a perspective view showing a worn state of the electric discharge machining electrode wire and a secondary machined portion of the workpiece in a second machining step. [Figure 5A] FIG. 10 is a schematic diagram showing a wire electric discharge machine according to another embodiment in a state of a first machining step. [Figure 5B] 5B is a schematic diagram showing the wire electric discharge machine in a state where the traveling mechanism shown in FIG. 5A is inverted. FIG. [Figure 5C] FIG. 5B is a schematic diagram showing the wire electric discharge machine of FIG. 5A in a state of a second machining step. [Figure 6] FIG. 10 is a schematic diagram showing a wire electric discharge machine according to still another embodiment. [Figure 7] 7 is a perspective view showing a workpiece and first and second electric discharge machining electrode wires in the wire electric discharge machine shown in FIG. 6. FIG. [Figure 8] FIG. 10 is a schematic diagram showing a wire electric discharge machine according to still another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Wire EDM] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. A wire electric discharge machine 10a shown in Figures 1A to 1C has a work table 11 on which a workpiece W is placed. The work table 11 is placed in a machining tank 12 that contains machining fluid, and the workpiece W is placed while immersed in the machining fluid. The work table 11 is movable left and right in the figure (X-axis direction) and also movable in a direction perpendicular to the plane of the paper (Y-axis direction), and the work table 11 is movable along a horizontal plane.

[0014] [First running mechanism] The wire electric discharge machine 10a has a first traveling mechanism 21a and a second traveling mechanism 21b. The first traveling mechanism 21a has a support frame 22a on the electrode wire supply side and a support frame 23a on the electrode wire drive side, and both support frames 22a, 22b are integrated by a connecting part (not shown). The support frame 22a of the first traveling mechanism 21a is arranged above the workpiece W, and the support frame 23a is arranged below.

[0015] A bobbin 25a around which a first electric discharge machining electrode wire (hereinafter also referred to as the first electrode wire) 24a is wound is rotatably mounted on the upper support frame 22a. A guide die 26a that guides the first electrode wire 24a unwound from the bobbin 25a toward the workpiece W is mounted on the support frame 22a. A guide roller 27a is rotatably mounted on the support frame 22a and positioned between the bobbin 25a and the guide die 26a, and the guide roller 27a guides the first electrode wire 24a to the guide die 26a.

[0016] A guide die 31a is attached to the support frame 23a below the first traveling mechanism 21a, facing the guide die 26a across the workpiece W, and the first electrode wire 24a after machining the workpiece W is inserted into the guide die 31a. A pair of traveling rollers 32a for unwinding the first electrode wire 24a from the bobbin 25a and traveling it is rotatably attached to the support frame 23a. A guide roller 33a is rotatably attached to the support frame 23a, positioned between the guide die 31a and the pair of traveling rollers 32a, and the guide roller 33a guides the first electrode wire 24a to the pair of traveling rollers 32a.

[0017] As described above, in the first traveling mechanism 21a, the bobbin 25a is placed above the workpiece W, and the workpiece W is moved horizontally for processing, so that the first electrode wire 24a unwound from the supply bobbin 25a travels in the vertical direction of the workpiece W, that is, from top to bottom in the Z-axis direction. The direction from top to bottom in the Z-axis direction is defined as the first direction.

[0018] [Second running mechanism] Similar to the first traveling mechanism 21a, the second traveling mechanism 21b includes a support frame 22b on the electrode wire supply side and a support frame 23b on the electrode wire drive side, and both support frames 22b, 23b are connected by a connecting portion (not shown). Unlike the first traveling mechanism 21a, the support frame 22b of the second traveling mechanism 21b is disposed below the workpiece W, and the support frame 23b is disposed above. A bobbin 25b around which a second electric discharge machining electrode wire (hereinafter also referred to as the second electrode wire) 24b is wound is rotatably mounted on the support frame 22b of the second traveling mechanism 21b. A guide die 26b that guides the second electrode wire 24b unwound from the bobbin 25b toward the workpiece W is mounted on the support frame 22b. A guide roller 27b is rotatably mounted on the support frame 22b, positioned between the bobbin 25b and the guide die 26b, and the guide roller 27b guides the second electrode wire 24b to the guide die 26b. The second electrode wire 24b has the same wire diameter as the first electrode wire 24a.

[0019] A guide die 31b is attached to the support frame 23b above the second traveling mechanism 21b, facing the guide die 26b across the workpiece W, and the second electrode wire 24b after machining the workpiece W is inserted into the guide die 31b. A pair of traveling rollers 32b for unwinding the second electrode wire 24b from the bobbin 25b and traveling it is rotatably attached to the support frame 23b. A guide roller 33b is rotatably attached to the support frame 23b, positioned between the guide die 31b and the pair of traveling rollers 32b, and the guide roller 33b guides the second electrode wire 24b to the pair of traveling rollers 32b.

[0020] As described above, in the second traveling mechanism 21b, the bobbin 25b is disposed below the workpiece W, and the workpiece W is moved horizontally for processing. Therefore, the second electrode wire 24b unwound from the supply bobbin 25b travels in the vertical direction of the workpiece W, that is, from bottom to top in the Z-axis direction. The direction from bottom to top in the Z-axis direction is defined as the second direction. The first direction, which is the traveling direction of the first electrode wire 24a, and the second direction, which is the traveling direction of the second electrode wire 24b, are opposite to each other.

[0021] To machine the workpiece W using the first electrode wire 24a of the first traveling mechanism 21a, the tip of the first electrode wire 24a is unwound downward from the bobbin 25a toward the guide die 26a, as shown in Fig. 1B. The unwound first electrode wire 24a is pulled out by a connecting wire 34a, and the first electrode wire 24a is passed over a guide roller 33a of the support frame 23a and attached to the pair of traveling rollers 32a. In this state, when the pair of traveling rollers 32a is rotated, the first electrode wire 24a is driven to travel and is passed over the pair of traveling rollers 32a.

[0022] To machine the workpiece W using the second electrode wire 24b of the second traveling mechanism 21b, as shown in FIG. 1C, the tip of the second electrode wire 24b is unwound upward from the bobbin 25b toward the guide die 26b. The unwound second electrode wire 24b is drawn out by the connecting wire 34b, similar to the first electrode wire 24a, and is stretched across the guide roller 33a. This allows the second electrode wire 24b to travel when the traveling roller pair 32b is driven to rotate. FIG. 1A shows a state in which the tip of the first electrode wire 24a approaches the vicinity of the guide die 26a, and a state in which the tip of the second electrode wire 24b approaches the vicinity of the guide die 26b.

[0023] Fig. 2 is a block diagram showing the control circuit of the wire electric discharge machine 10a. As shown in Fig. 2, a control signal is sent from a control unit 40 to a first travel motor 41a that rotates and drives the pair of travel rollers 32a of the first travel mechanism 21a and a second travel motor 41b that rotates and drives the pair of travel rollers 32b of the second travel mechanism 21b. A control signal is sent from the control unit 40 to an X-axis movement motor 42 that moves the work table 11 in the X-axis direction for machining, and a Y-axis movement motor 43 that moves the work table 11 in the Y-axis direction for machining. Furthermore, a machining power supply 44 that supplies power to each of the electrode wires 24a, 24b and the workpiece W is controlled by the control unit 40.

[0024] An operation panel 45 is connected to the control unit 40, and the operation panel 45 is equipped with buttons for instructing the wire electric discharge machine 10a to start machining and buttons for instructing the work table 11 to move to a new position. The control unit 40 has a memory for storing control programs, arithmetic expressions, map data, etc., and a processor for calculating control signals.

[0025] The work table 11 and the motors 42, 43 constitute a machining movement mechanism that moves the workpiece W relative to the electrode wires 24a, 24b for machining. However, the machining movement of the workpiece W relative to the electrode wires 24a, 24b only needs to be relative, and the electrode wires 24a, 24b may be moved relative to the workpiece W for machining.

[0026] [Wire EDM method] When electrical discharge machining is performed on the workpiece W, the workpiece W is placed on the workpiece table 11 as shown in FIG. 1A. Meanwhile, the first electrode wire 24a of the first traveling mechanism 21a is unwound from the bobbin 25a and attached to the traveling roller pair 32a. The portion of the workpiece W to be machined is positioned relative to the electrode wire 24a by moving the workpiece table 11 in two axial directions, the X and Y axes. In this state, the workpiece table 11 is moved relative to the electrode wire 24a for machining.

[0027] [First processing step] 1B shows a state in which the workpiece W is being primarily machined, i.e., a state in which the first machining step is being performed. At this time, the workpiece W is placed in the machining fluid in the machining tank 12, and power is applied from the machining power source 44 to the workpiece W and the electrode wire 24a in a state in which the workpiece W and the electrode wire 24a face each other with a small gap between them.

[0028] In the first machining step, the work table 11 is moved for machining, and the first electrode wire 24a is caused to travel in a first direction from above to below the workpiece W. As a result, arc discharge is repeatedly generated between the workpiece W and the electrode wire 24a, thereby removing and machining the machining portion of the workpiece W. At this time, the upper end surface of the workpiece W is defined as the approach portion where the electrode wire approaches, and the lower end surface of the workpiece W is defined as the passing portion where the electrode wire passes, and the electrode wire 24a travels downward from the approach portion of the workpiece W along the passing portion. As each portion of the electrode wire 24a travels from the approach portion to the passing portion, an arc discharge is generated between the workpiece and the electrode wire 24a. As the workpiece W is machined, the electrode wire 24a is also consumed, reducing its wire diameter.

[0029] FIG. 3A shows a state in which a primary processing portion 51 is being processed on a workpiece W by primary processing using a first electrode wire 24a. The primary processing portion 51 has a processing start portion 51a at the leading end of the processing movement direction of the workpiece W, a portion 51b extending in the X-axis direction, a portion 51c extending in the Y-axis direction, and a portion 51d further extending in the X-axis direction, each of which penetrates in the Z-axis direction. By moving the work table 11 in two axial directions, the primary processing portion 51 is formed as shown in FIG. 3A. The work table 11 is not shown in FIGS. 3A and 3B, and supports a position on the workpiece W that does not interfere with the primary processing portion 51. [Second processing step] After the primary machining is completed by the first electrode wire 24a and the primary machining portion 51 is machined, the workpiece W is returned to its position before the primary machining by the work table 11, and the processed portion of the electrode wire 24a of the first traveling mechanism 21a is removed. Meanwhile, the second electrode wire 24b of the second traveling mechanism 21b is unwound from the bobbin 25b and attached to the traveling roller pair 32b. Next, the primary machining portion 51 is subjected to secondary machining by the second electrode wire 24b. In the second machining step, the workpiece W is first positioned and moved by the work table 11 so that the position of the machining start portion 51a of the primary machining portion 51 is aligned with the position of the second electrode wire 24b.

[0030] 1C shows a state in which the already machined primary processed portion 51 is being subjected to secondary processing, i.e., a state in which the second processing step is being performed. At this time, as in the processing of the primary processed portion 51 by the electrode wire 24a, power is applied from the processing power source 44 to the workpiece W and the electrode wire 24b in a state in which the workpiece W and the electrode wire 24b face each other with a small gap therebetween.

[0031] In the second machining step, the work table 11 is moved in the same manner as in the first machining step, and the second electrode wire 24b is moved in a second direction from below to above the workpiece W. This causes repeated arc discharges between the workpiece W and the electrode wire 24b, thereby removing and machining the machining portion of the workpiece W. At this time, the lower end surface of the workpiece W is defined as the approach portion where the electrode wire approaches, and the lower end surface of the workpiece W is defined as the passing portion where the electrode wire passes. The electrode wire 24b moves upward from the approach portion of the workpiece W along the passing portion. As each portion of the electrode wire 24b moves from the approach portion to the passing portion, an arc discharge is generated between the workpiece W and the electrode wire 24b. As the workpiece W is machined, the electrode wire 24b is also consumed, reducing its wire diameter. The second direction is opposite to the first direction.

[0032] 3B shows a state in which a secondary processed portion 52 is machined on the workpiece W by secondary processing using the second electrode wire 24b. The secondary processed portion 52 is electric discharge machined by a new, unmachined electrode wire 24b by moving the workpiece W in the same manner as when the primary processed portion 51 was machined, so as to trace the primary processed portion 51.

[0033] [Primary processing department] FIG. 4A is a perspective view showing the wear state of the electric discharge machining electrode wire 24a in the first machining step and the primary machined portion 51 of the workpiece W, and FIG. 4B is a perspective view showing the wear state of the electric discharge machining electrode wire 24b in the second machining step and the secondary machined portion 52 of the workpiece W.

[0034] As shown in Fig. 4A, in the first machining step, the first electrode wire 24a traveling in the first direction has a portion where its unmachined portion comes closest to the workpiece W and starts to discharge, which is defined as an approaching portion 61a on the workpiece W, and a portion where the electrode wire 24a moves away from the workpiece W as it travels and ends to discharge, which is defined as a passing portion 61b on the workpiece W. Each portion of the electrode wire 24a that has traveled up to the approaching portion 61a is worn out before it reaches the passing portion 61b, and as shown in Fig. 4A, the wire diameter or width gradually decreases toward the passing portion 61b. If the wire diameter of the electrode wire 24a before machining is D and the wire diameter after machining is d, then d <Dとなる。

[0035] On the one hand, in the state where the primary machining is completed, the width dimension F of the passing portion 61b of the primary machining portion 51 formed between the approaching portion 61a and the passing portion 61b of the workpiece W is smaller than the width dimension E of the approaching portion 61a (F < E). This is because when the wire diameter of the electrode wire 24a becomes smaller as it is consumed and moves toward the passing portion 61b, the distance between the electrode wire 24a and the workpiece W becomes larger, and the melting amount of the workpiece becomes smaller. Therefore, as shown in FIG. 4A, the width dimension of the primary machining portion 51 gradually decreases from the approaching portion 61a toward the passing portion 61b.

[0036] [Secondary machining portion] In the second machining step, as shown in FIG. 4B, since the second electrode wire 24b travels and moves in the second direction, the approaching portion 62a, which is the portion where the unprocessed portion of the electrode wire 24b is closest to the workpiece W and where the discharge starts, is the passing portion 61b by the first electrode wire 24a. And the passing portion 62b, which is the portion where the electrode wire 24b moves away from the workpiece and the discharge ends as it travels and moves, is the approaching portion 61a of the first electrode wire 24a. Each portion of the electrode wire 24b that has traveled and moved to the approaching portion 62a is consumed before it travels to the passing portion 62b, and as shown in FIG. 4B, the wire diameter or wire width gradually decreases as it moves toward the passing portion 62b. This is the same as the first electrode wire 24a that machined the primary machining portion 51.

[0037] As described above, the width dimension F of the passing portion 61b of the primary machining portion 51 is smaller than the width dimension E of the approaching portion 61a of the workpiece W. In the second machining step, the narrower side of the width in the primary machining portion 51 is used as the approaching portion 62a, which is the machining start portion of the secondary machining, and machining is performed with the unconsumed electrode wire 24b. Since the distance between the second electrode wire 24b and the passing portion 61b side of the primary machining portion 51 is smaller than the distance from the approaching portion 61a side, the machining amount, that is, the removal amount, of the workpiece W by the second electrode wire 24b is larger on the passing portion 61b side.

[0038] Therefore, both the upper and lower portions of the workpiece W are machined using a non-consumable electrode wire, and as shown in Fig. 4B, the width of the approaching portion 62a of the secondary machining portion 52 and the width of the passing portion 62b are approximately the same width dimension G, thereby reducing the error in the machining dimensions of the approaching portion 62a and the passing portion 62b of the secondary machining portion 52. In this way, the second machining process functions as a finishing process that finishes the primary machining portion 51, and can improve the machining accuracy of wire electrical discharge machining.

[0039] The first traveling mechanism 21a and the second traveling mechanism 21b have almost the same structure, with the traveling mechanism that performs the primary processing being designated as the first traveling mechanism, and the traveling mechanism that performs the secondary processing being designated as the second traveling mechanism that is different from the first traveling mechanism. It is optional which of the two traveling mechanisms 21a, 21b is used to perform the primary processing, and if the primary processing and secondary processing are performed by different traveling mechanisms, it is also possible to perform the primary processing by traveling mechanism 21b and the secondary processing by traveling mechanism 21a.

[0040] [Other embodiments] 5A to 5C are schematic diagrams showing a wire electric discharge machine 10b according to another embodiment. This wire electric discharge machine 10b has a single traveling mechanism 21, which is provided with a supply-side support frame 22 for supplying the electrode wire and a drive-side support frame 23 for driving the electrode wire, and both support frames 22, 23 are connected by a connecting portion 28.

[0041] A bobbin 25 around which an electric discharge machining electrode wire (hereinafter also referred to as electrode wire) 24 is wound is rotatably mounted on the supply-side support frame 22. A guide die 26 that guides the electrode wire 24 unwound from the bobbin 25 toward the workpiece W is mounted on the support frame 22. A guide roller 27 is rotatably mounted on the supply-side support frame 22, positioned between the bobbin 25 and the guide die 26, and the guide roller 27 guides the electrode wire 24 to the guide die 26a.

[0042] A guide die 31 is attached to the drive-side support frame 23, facing the guide die 26 across the workpiece W, and the electrode wire 24 after machining the workpiece W is inserted into the guide die 31. A pair of running rollers 32 for unwinding the electrode wire 24 from the bobbin 25 and moving it is rotatably attached to the support frame 23. A guide roller 33 is rotatably attached to the drive-side support frame 23, positioned between the guide die 31 and the pair of running rollers 32, and the guide roller 33 guides the electrode wire 24 to the pair of running rollers 32.

[0043] A reversing mechanism 35 is provided on the traveling mechanism 21 as shown by the arrow in Fig. 5B, and the reversing mechanism 35 reverses the up-down relationship between the support frame 22 on the supply side of the traveling mechanism 21 and the support frame 23 on the drive side. Therefore, the reversing mechanism 35 can reverse the traveling mechanism 21 to either a first direction in which the electrode wire 24 travels from above to below the workpiece W as shown in Fig. 5A, or a second direction in which the electrode wire 24 travels from below to above the workpiece W as shown in Fig. 5C.

[0044] In this wire electric discharge machine 10b, as shown in Fig. 5A, a first machining step is performed by moving the workpiece W by the work table 11 while unwinding the electrode wire 24 from the bobbin 25 located above the workpiece W and running it in a first direction. As with the wire electric discharge machine 10a described above, this causes a primary machining portion 51 to be machined on the workpiece W. After machining of the primary machining portion 51 is completed, as shown in Fig. 5B, the work table 11 returns the machining start portion 51a of the workpiece W to its position before machining started. In this state, the reversing mechanism 35 turns the support frames 22, 23 upside down.

[0045] 5C shows the wire electric discharge machine 10b with the traveling mechanism 21 inverted and performing the second machining step using the electrode wire 24. In the second machining step, as with the wire electric discharge machine 10a described above, an unused electrode wire 24 unwound from the bobbin 25 is used to machine a primary machined portion 51 and form a secondary machined portion 52 in the workpiece W as a finishing process.

[0046] Fig. 6 is a schematic diagram showing a wire electric discharge machine 10c according to still another embodiment. Fig. 7 is a perspective view showing a workpiece W and first and second electric discharge machining electrode wires 24a, 24b in the wire electric discharge machine 10c shown in Fig. 6.

[0047] Like the wire electric discharge machine 10a, the wire electric discharge machine 10c includes a first traveling mechanism 21a and a second traveling mechanism 21b. The structures of the traveling mechanisms 21a and 21b are the same as those of the wire electric discharge machine 10a, and therefore, redundant explanations will be omitted.

[0048] 6 and 7, in wire electric discharge machine 10c, before the first electrode wire 24a of traveling mechanism 21a traveling in a first direction completes machining of primary-machined portion 51, the second electrode wire 24b of traveling mechanism 21b traveling in a second direction performs secondary machining on primary-machined portion 51 to machine secondary-machined portion 52. With wire electric discharge machine 10c, the second machining step is started before the first machining step is completed, thereby improving machining efficiency.

[0049] 7, a start hole 53 is formed in advance in the workpiece W, and the first machining step and the second machining step are started after the electrode wires 24a, 24b are respectively passed through the start hole 53. Note that the above-described wire electric discharge machines 10a, 10b, and 10c can also machine workpieces in which a start hole is formed in advance.

[0050] Figure 8 is a schematic diagram showing a wire electric discharge machine 10d according to yet another embodiment. This wire electric discharge machine 10d is equipped with a first traveling mechanism 21a and a second traveling mechanism 21b, similar to the wire electric discharge machine 10c shown in Figure 6. The structures of the traveling mechanisms 21a and 21b are the same as those of the wire electric discharge machine 10c, and therefore redundant explanations will be omitted.

[0051] In the wire electric discharge machine 10c, the first traveling mechanism 21a and the second traveling mechanism 21b are arranged to face each other, whereas in the wire electric discharge machine 10d shown in Fig. 8, the two traveling mechanisms 21a, 21b are arranged to overlap on the same side in the machining movement direction of the work table 11. Like the wire electric discharge machine 10c shown in Fig. 6, the wire electric discharge machine 10d can start the second machining process using the second electrode wire 24b before the first machining process using the first electrode wire 24a is completed.

[0052] In each of the wire electric discharge machines 10b to 10d, both the upper and lower portions of the workpiece W are machined using non-consumable electrode wires, and as shown in Fig. 4B, the width of the approaching portion 62a of the secondary processing section 52 and the width of the passing portion 62b are approximately the same width dimension G, thereby reducing the error in the machining dimensions of the approaching portion 62a and the passing portion 62b of the secondary processing section 52. This allows the wire electric discharge machines 10b to 10d to improve the machining accuracy of wire electric discharge machining.

[0053] In the above-described wire electric discharge machines 10c and 10d, primary machining may be performed by a traveling mechanism 21b, similar to the wire electric discharge machine 10a.

[0054] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present invention. For example, in the above-described wire electric discharge machines 10a to 10d, the workpiece W is moved horizontally for machining and the electrode wire is moved vertically for running. However, the workpiece W may be moved vertically or inclined for machining. In this case, the electrode wire is moved horizontally or inclined so as to cross the workpiece. When the electrode wire is moved horizontally, a first electrode wire is moved from one side, left or right, and a second electrode wire is moved from the other side, left or right. [Explanation of symbols]

[0055] 10a~10d Wire electric discharge machine 11 Work table 12 Processing tank 21 Running mechanism 21a First traveling mechanism 21b Second traveling mechanism 22, 22a, 22b Support frame 23, 23a, 23b Support frame 24 Electrode wire for electrical discharge machining 24a First electric discharge machining electrode wire 24b Second electric discharge machining electrode wire 25, 25a, 25b bobbins 26, 26a, 26b Guide dies 31, 31a, 31b Guide dies 32, 32a, 32b Pair of running rollers 35 Reversal mechanism 51 Primary processing department 52 Secondary processing department

Claims

1. A wire electric discharge machining method for machining a workpiece using an electric discharge machining electrode wire, comprising: a first machining step of primarily machining the workpiece by running an unused first electric discharge machining electrode wire along a first direction of the workpiece; a second machining step of secondarily machining the primary machined portion machined using the first electric discharge machining electrode wire by running one unused second electric discharge machining electrode wire along a second direction of the workpiece that is a direction opposite to the first direction, the second processing step is initiated after the first processing step is completed; The wire diameter of the unused first electric discharge machining electrode wire is the same as the wire diameter of the unused second electric discharge machining electrode wire. Wire electrical discharge machining method.

2. the second electric discharge machining electrode wire is supplied in a second direction of the workpiece by a traveling mechanism different from a traveling mechanism that supplies the first electric discharge machining electrode wire to the workpiece; The wire electric discharge machining method according to claim 1 .

3. the second electric discharge machining electrode wire is supplied in a second direction of the workpiece by the same traveling mechanism as that which supplies the first electric discharge machining electrode wire to the workpiece; The wire electric discharge machining method according to claim 1 .

4. A wire electric discharge machine that processes a workpiece using an electric discharge machining electrode wire, a first traveling mechanism that performs primary machining on the workpiece by traveling an unused first electric discharge machining electrode wire along a first direction of the workpiece; a second traveling mechanism that travels an unused second electric discharge machining electrode wire along a second direction of the workpiece that is a direction opposite to the first direction, thereby performing secondary machining on the primary machined portion machined using the first electric discharge machining electrode wire; the second traveling mechanism performs secondary machining on the primary machined portion with the second electric discharge machining electrode wire after primary machining of the workpiece with the first electric discharge machining electrode wire is completed; The wire diameter of the unused first electric discharge machining electrode wire is the same as the wire diameter of the unused second electric discharge machining electrode wire. Wire electric discharge machine.

5. A wire electric discharge machine that processes a workpiece using an electric discharge machining electrode wire, a traveling mechanism that performs primary machining on the workpiece by running an electric discharge machining electrode wire along a first direction of the workpiece, and performs secondary machining on the primarily machined portion by running the electric discharge machining electrode wire in a second direction of the workpiece that is opposite to the first direction; a reversing mechanism that reverses the position of the traveling mechanism from a position where the electric discharge machining electrode wire travels in the first direction to a position where the electric discharge machining electrode wire travels in the second direction after the primary machining is completed; A wire electric discharge machine having a

6. 6. The wire electric discharge machine according to claim 4, further comprising a machining movement mechanism that moves the workpiece and the electric discharge machining electrode wire relatively in a machining movement direction.

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