JP5825143B2 - EDM machine - Google Patents

Description

  The present invention relates to an electric discharge machining apparatus capable of increasing machining efficiency by efficiently discharging sludge and the like from a machining portion during electric discharge machining.

  In the electric discharge machining, the machining proceeds while the distance between the electrode 10 and the workpiece W is always maintained at an interval suitable for the generation of electric discharge (distance between the electrodes). For electric discharge machining, there are three states: a discharge state within the distance between the electrodes, an open state in which the distance between the electrode 10 and the workpiece W is greater than the distance between the electrodes, and a short-circuit state in which the electrode 10 is in contact with the workpiece W Among these three states, machining progresses only in the discharge state, and increasing the time ratio of the discharge state leads to higher efficiency.

  One of the factors that cause the low time ratio of the discharge state is that the discharge to the workpiece W is less likely to occur due to the generation of bubbles and the retention of machining waste (sludge). In particular, in the electric discharge machining of fine holes (50 to 300 μm) as shown in FIG. 1, the generation of bubbles generated by electric discharge machining and the processing scraps are likely to remain in the processed portion and are difficult to be discharged. If a large amount of machining waste is present in the gap between the electrode 10 and the workpiece (for example, about 5 μm), a discharge phenomenon occurs at a place where machining is not necessary, or an arc phenomenon occurs continuously, causing abnormal machining. Or the tool electrode 10 and the workpiece W are short-circuited so that the processing does not proceed, so that the processing does not progress. Accordingly, it is an effective means for increasing the processing speed and improving the processing accuracy to quickly discharge the processing waste generated by the processing from the processing portion.

  Also, as shown in FIG. 2, bubbles may stay due to surface tension. When the buoyancy of the bubbles becomes larger than the surface tension, the bubbles are discharged together with the sludge. However, since such bubbles continue to stay until they have a certain buoyancy, the discharge performance is deteriorated.

  Examples of the technology for improving the discharge efficiency of the processing waste include a method of using a pipe-shaped processing electrode, vibrating the processing electrode, rotating the processing electrode, and spraying a processing liquid on the processing portion from the outside. . However, in the method using a pipe-shaped machining electrode, there is a possibility that the following problems may occur when producing a micro-hole machining portion. Here, the pipe-shaped machining electrode indicates a machining electrode in which a machining liquid injection path is provided in the pipe. By injecting the machining liquid from the machining liquid injection path into the machining part, sludge in the machining part is formed. It is configured so that it can be blown away. In order to process a fine processed portion, it is necessary to reduce the diameter of the processing electrode, and accordingly, the diameter of the processing liquid injection path must also be reduced. Therefore, a very high pressure is required for injecting the machining liquid, and there is a possibility that the infusion of the machining liquid may be difficult. Moreover, it is very difficult and expensive to produce such a fine processed electrode.

  On the other hand, with respect to the method of vibrating the machining electrode, the pumping effect is produced by vibrating the machining electrode, and the sludge discharge efficiency can be increased by ejecting the machining liquid from the machining portion. However, when the diameter of the machining electrode is thin and the rigidity is low, the machining electrode may be easily damaged. Further, when the machining electrode having low rigidity is vibrated, the machining electrode is shaken or bent, and the machining accuracy may be lowered, or the workpiece electrode may be easily brought into contact with the workpiece W to increase the frequency of occurrence of a short circuit.

  Further, in the method of rotating the machining electrode, the machining liquid is agitated by rotating the machining electrode, and a flow is generated in the machining liquid, so that the sludge discharge efficiency can be increased. However, when the diameter of the machining electrode is small, the force for stirring the machining liquid is weak, and it is difficult to obtain a sufficient sludge discharge effect. The problem described above is a problem that often occurs when the diameter of the processed portion is smaller than 200 μm, and particularly occurs when the diameter of the processed portion is smaller than 100 μm.

  In recent years, air discharge machining has attracted attention, and Patent Document 1 discloses air discharge machining in which mist is supplied from the outside. However, as can be seen in FIGS. 3 and 4 even when such mist is supplied, if it is attempted to blow from the outside periphery during micro-hole processing, the flow of the exhaust air flow may be hindered or water droplets from the mist may adhere to the electrode. As a result, there has been a concern that mist cannot be supplied to the bottom of the electrode or that an excessive amount is supplied.

JP 2006-102828 A

  In view of the above problems, the present invention provides an electric discharge machining apparatus capable of increasing machining efficiency by efficiently discharging sludge and the like from a machining portion during electric discharge machining.

In order to solve the above-mentioned problems, the invention of claim 1 includes a rod-shaped machining electrode (10) and an electrode guide (4) for guiding the machining electrode (10) along the axial direction of the machining electrode (10). ) And a pulse power supply unit (11) that repeatedly generates a discharge by applying intermittent voltage pulses between the machining electrode (10) and the workpiece (W). In the electric discharge machining apparatus for machining a microhole or a cavity of a predetermined shape, a mist supply flow path section for supplying a mist obtained by misting a machining liquid is installed in the electrode guide (4), and the mist supply flow path section Is composed of two or more mist channel grooves (21-1, 21-2) provided along the axial direction on the inner peripheral surface of the electrode guide, and is a microhole of a workpiece to be subjected to electric discharge machining. (2a), the mist concentrically with the axis Fed, further, the feedback channel (21-3) is provided between the two or more mist flow grooves (21-1, 21-2), the two or more mist flow grooves (21-1 , 21-2) .

  In addition, the code | symbol attached | subjected above is an example which shows a corresponding relationship with the specific embodiment as described in embodiment mentioned later.

It is explanatory drawing of the electrical discharge machining by a prior art. It is explanatory drawing of the electrical discharge machining by a prior art. It is explanatory drawing of the air discharge machining by a prior art. It is explanatory drawing of the air discharge machining by a prior art. It is a conceptual diagram explaining the whole structure of the electric discharge machining apparatus in one Embodiment of this invention. It is explanatory drawing of the electrical discharge machining in one Embodiment of this invention. It is explanatory drawing (plane cross section) of the mist supply in the electric discharge machining in one Embodiment of this invention. It is explanatory drawing (front cross section) of the electrical discharge machining in one form. It is explanatory drawing (plane cross section) of the electrical discharge machining in one form.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. About each embodiment, the same code | symbol is attached | subjected to the part of the same structure, and the description is abbreviate | omitted.
In the air discharge machining, it is required to improve the discharge efficiency of the machining waste by supplying an appropriate amount of the machining fluid to take advantage of the effect of vaporization explosion and to suppress the convection stagnation in the machining hole. From the viewpoint of improving the sludge discharge performance, it is appropriate that the entire circumference of the hole is not immersed in water. As a means for supplying an appropriate amount of machining fluid in such an in-air electric discharge machining, machining by mist supply can be mentioned. There are two methods for supplying the mist: a method for supplying the mist coaxially with the electrode and a method for supplying from the nozzle. The present embodiment is the former, in which a mist flow path is provided in the electrode guide portion and supplied coaxially. The flow path shape may be a structure that can distinguish the inflow position and the outflow position into the processing hole when supplied to the processing hole. In the present embodiment, as the mist supply flow path portion, the mist supply flow path is provided as grooves 21-1 and 21-2 along the axial center O of the electrode on the guide inner peripheral surface 23 (FIG. 7). It is. This groove may be single, but if it is installed in pairs so as to be opposed to the shaft center, an exhaust flow between them is effectively generated.

  First, the electric discharge machining apparatus of this embodiment will be described. As shown in FIG. 5, the processing electrode 10 is rotatably attached to the electrode feed head 8 via the electrode guide 4. The electrode feed head 8 includes a holding unit 6 that holds the machining electrode 10 and a rotation drive unit (motor) 7 that rotates the machining electrode 10 around the central axis of the motor. Thereby, the processing electrode 10 and the holding unit 6 are rotated together by the rotation driving unit 7. The electrode feed head 8 to which the holding unit 6 and the machining electrode 10 are rotatably attached is attached to a first NC shaft 9 that is movable in the vertical direction. The feed amount of the machining electrode 10 by the first NC shaft 9 is as follows. The control unit 13 performs batch control. The rotation drive unit 7 is also controlled by the control unit 13. Here, although it described as what is processed so that the process electrode 10 may rotate, it may be a case where it does not rotate at the time of a process, and the rotation drive part (motor) 7 is not necessarily essential.

  Similarly to the electrode feed head 8, the electrode guide 4 that guides the processing electrode 10 can also be moved in the vertical direction by the electrode guide adjustment mechanism 5. The electrode guide adjusting mechanism 5 includes a head portion 5a to which the electrode guide 4 is attached and a second NC shaft 5b to which the head portion 5a is attached. The amount of movement of the electrode guide 4 by the second NC shaft 5b is as follows. It is controlled by the control unit 13 in the same manner as the electrode feed head 8. As the diameter of the through-hole processed in the workpiece W decreases, the diameter of the processing electrode 10 decreases accordingly, and the rigidity of the processing electrode 10 decreases. The electrode guide 4 is provided to prevent the rigidity of the machining electrode 10 from being lowered.

  The workpiece W is placed and fixed on the processing table 3. The machining table 3 can be rotated not only in the X-axis, Y-axis, and Z-axis directions, but also in the θ-angle direction around the Z-axis, and can be inclined at an α angle with respect to the XY plane. The table is movable and tiltable in the XYZ-θ-α direction, and is controlled by the control unit 13. The processing table 3 is placed and fixed on an apparatus main body (not shown).

Reference numeral 11 denotes a pulse power supply unit for applying a voltage between the machining electrode 10 and the workpiece W during machining. For example, a voltage pulse is applied from the pulse power supply unit 11 between the machining electrode 10 and the workpiece W. During the formation of the hole 2a in the workpiece W by electric discharge machining, machining scraps and the like are generated. An air supply pipe 12-1 and a cooling liquid (processing liquid) supply pipe 12-2 are supplied to the electrode guide 4 attached to the head part 5 a so that air and cooling liquid are supplied from the mist supply part 12. It is connected with a flexible hose. A mist is formed in the electrode guide 4 by air, and the mist is supplied to the hole 2a of the workpiece W. The mist supply unit 12 is appropriately controlled by the control unit 13 so that the supply amount, supply pressure, supply timing, and the like are controlled.
The electric discharge machining apparatus described above is an example, and the present embodiment can be applied to an electric discharge machining apparatus having another overall configuration. Wire cut discharge is excluded.

Details of the mist supply will be described with reference to FIGS.
Mist is formed by air inside the electrode guide 4. The electrode guide part 4 is provided with elongated mist channel grooves 21-1 and 21-2 along the axis O as a mist supply channel part on the inner peripheral surface 23 of the electrode guide 4. The mist is coaxially supplied to the hole 2a of the workpiece W along the surface of the machining electrode 10 along the mist channel grooves 21-1 and 21-2. The important point here is that the mist is not supplied over the entire circumference of the machining electrode 10, but as shown in FIG. 7, the return flow path 21-3 for discharging is a mist flow path groove 21-. It is a point provided between 1 and 21-2.

  The mist flow supplied downward along the mist channel grooves 21-1 and 21-2 rises in the return channel 21-3 so as to discharge the processing waste. Thereby, since the processing waste generated by the processing can be quickly discharged from the processing portion, it is possible to increase the processing speed and improve the processing accuracy. The flow path shape may be any structure as long as it can distinguish the inflow direction and the outflow direction into the processing hole when supplied to the processing hole. The mist flow channel grooves 21-1 and 21-2 may be single, but if the mist flow channel grooves 21-1 and 21-2 are installed in pairs so as to face the axis O, the discharge flow becomes easy. It is also possible to install three mist channel grooves at intervals of 120 degrees. If there are too many mist channel grooves, a return channel cannot be secured. Therefore, the number of mist channel grooves is preferably 2 or 3 with respect to the axis O. As shown in FIG. 7, a suction device or a magnet (permanent magnet or electromagnet) 22 may be provided in the discharge direction in the return flow path to promote sludge discharge.

Next, the amount of mist supplied will be described. The mist is controlled by the mist supply unit so as to supply the amount evaporated by the discharge. If the mist supply amount M is larger than the evaporation amount G, water accumulates at the bottom and sludge stays, so that the processing efficiency is lowered. If the opposite is true (M <G), the discharge is difficult to fly and the efficiency is lowered. The mist supply unit is controlled by calculating from the heating amount so that the mist supply amount M = the evaporation amount G.
As a result, the machining efficiency can be improved, and the mist is sufficiently supplied coaxially along the machining electrode 10 to the bottom of the machining electrode and is discharged well upward, thereby promoting sludge retention. Can do.

Another form is as follows. In this embodiment , a mist supply channel 31 for supplying mist by a tube is provided on the electrode guide 4 on the front side in the traveling direction of the machining electrode 10, and a suction pipe for sucking sludge on the rear side of the machining electrode 10 or A suction part 32 made of a magnet is installed on the electrode guide 4. In the case of FIG. 9, it is an example which processes the groove part with a circular bottom. Without being limited thereto, the present invention can be applied to various shape processing and cavity processing of a predetermined shape. Since the machining electrode 10, the mist supply flow path portion 31, and the suction portion 32 can be moved integrally with the electrode guide 4 around the center of the circular bottom, it is optimal even if the machining electrode 10 is tilted or swung. Mist can be supplied to a proper place, and sludge can be discharged well.

4 Electrode guide 10 Processing electrode 11 Pulse power unit

Claims (3)

A rod-shaped machining electrode (10), an electrode guide (4) for guiding the machining electrode (10) along the axial direction of the machining electrode (10), the machining electrode (10) and a workpiece (W And a pulse power supply unit (11) that repeatedly generates a discharge by applying intermittent voltage pulses to the workpiece (W) to process a microhole or a cavity of a predetermined shape in the workpiece (W). In the electrode guide (4), a mist supply flow path section for supplying a mist obtained by misting the machining liquid is installed ,
The mist supply flow path portion is composed of two or more mist flow path grooves (21-1, 21-2) provided along the axial direction on the inner peripheral surface of the electrode guide, and is subjected to electric discharge machining. The mist is supplied to the minute hole (2a) of the workpiece so as to be concentric with the axis, and the return channel (21-3) further includes the two or more mist channel grooves (21-1, 21). -2), and is connected to the two or more mist channel grooves (21-1, 21-2) . 2. The electric discharge machining apparatus according to claim 1 , wherein a magnet (22) is installed on an inner circumferential surface of the electrode guide between the two or more mist flow channel grooves to promote discharge of machining waste. . The supply amount of the mist in the discharge machining, electrical discharge machining apparatus according to claim 1 or 2 wherein the mist is characterized in that the supplied adjusted to the amount of evaporation.

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