JP2016055396A - Wire electric discharge machining method and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire electric discharge machining method enabling a long time stable wire electric discharge machining, a device to perform the method, and a means to prevent formation of verdigris, which may cause process trouble.SOLUTION: A wire electric discharge machining method uses water purified using an ion exchange resin (11) and further made free from any heavy metal ion, particularly a copper ion using an ion exchange resin (15), as a dielectric substance for the wire electric discharge machining. The wire electric discharge machining method enables a long time stable wire electric discharge machining, suppressing formation of verdigris.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wire electric discharge machining method and an apparatus thereof, and more particularly to a wire electric discharge machining method and an apparatus thereof that enable stable operation for a long time.

  Electric discharge machining is a machining method in which a part of the surface of a workpiece is removed by arc discharge repeated at short intervals between an electrode and the workpiece. Wire electric discharge machining is a type of electric discharge machining, in which a thin metal wire is used as an electrode, and the workpiece is cut into a desired shape by arc discharge between the workpiece and the workpiece. This is a processing method preferably used for precision processing of dies and the like. Water or oil is placed as a dielectric between the work piece and the wire. In the case of using water, a method of spraying water between a workpiece and a wire and a dipping method for filling water are generally known.

  When water is used as a dielectric, the resistivity (electric conductivity) of water is usually controlled to be in a certain range after being purified by ion exchange. In addition, other properties and properties of water have been improved. For example, Japanese Patent Laid-Open No. 2002-301624 (Patent Document 1) reduces the concentration of sulfate ions and chloride ions, which are corrosive ions, in order to prevent corrosion of a workpiece, while the electrical conductivity of water. A method has been proposed that does not raise the value. In this method, water is brought into contact with an anion exchange resin in which at least one of carbonate ion, hydrogen carbonate ion and hydroxide ion is fixed together with nitrite ion and water.

  However, as far as the present inventor knows, no proposal has been made so far to control the ion concentration of heavy metal with respect to water as a dielectric for wire processing discharge.

JP 2002-301624 A

  The present inventor has recently obtained the knowledge that by controlling the heavy metal ion concentration of water as a dielectric for wire electric discharge machining, stable wire electric discharge machining for a long time becomes possible. The present invention is based on this finding.

  Therefore, an object of the present invention is to provide a wire electric discharge machining method that enables stable wire electric discharge machining for a long time and an apparatus for carrying out the method.

  The wire electric discharge machining method according to the present invention is a method in which a discharge is generated between the wire and the workpiece, thereby removing a part of the workpiece and molding is performed. The removed water is placed between the wire and the workpiece as a dielectric.

  Further, according to one aspect of the present invention, after the water is placed as a dielectric between the wire and the workpiece, heavy metal ions are removed, and the wire and the workpiece are again disposed. Cycle to put on.

  According to a further preferred embodiment, heavy metal ions are removed by bringing water into contact with the ion exchange resin. According to a more preferred embodiment, the ion exchange resin has a chelate structure capable of capturing heavy metal ions.

  Further, a wire electric discharge machining apparatus according to the present invention is an apparatus for carrying out the above-described wire electric discharge machining method according to the present invention, and generates an electric discharge between the wire and the workpiece, whereby the workpiece is processed. Wire electric discharge machining means for forming a workpiece by removing a part of the wire, means for placing water as a dielectric between the wire and the workpiece, and heavy metal for removing heavy metal ions from the water And an ion removing means.

  According to one aspect of the present invention, a wire electric discharge machining apparatus according to the present invention introduces water placed as a dielectric between the wire and the workpiece into the heavy metal ion removing means to remove heavy metal ions. , And thereafter, means for circulating so as to be placed again between the wire and the workpiece.

  According to a further preferred embodiment, the heavy metal ion removing means is an ion exchange resin, and according to a more preferred embodiment, the ion exchange resin has a chelate structure capable of capturing heavy metal ions.

It is a figure explaining the system by which water as a dielectric material is circulated in a wire electric discharge machining apparatus. In the apparatus of FIG. 1, it is a figure which shows the structure which provided the pure water purification means 11 provided with the ion exchange resin for pure water, and the heavy metal ion removal means 15 in series with respect to the circulation path of water. In the apparatus of FIG. 1, it is a figure which shows the structure which provided the pure water means 11 provided with the ion exchange resin for pure water, and the heavy metal ion removal means 15 in parallel with respect to the circulation path of water.

Control of Heavy Metal Ions According to the present invention, long-term stable wire electric discharge machining can be performed by removing heavy metal ions. When the operation of the electric discharge machining apparatus was continued for a certain period of time, clogging of pores such as nozzles was observed in the water circulation path of the apparatus. As a result of controlling the presence of heavy metal ions in accordance with the present invention, the occurrence of such problems was greatly suppressed. By controlling the presence of heavy metal ions in accordance with the present invention, the occurrence of discoloration in the system, particularly in the place where it comes into contact with water or in the place where the water stays, etc., is no longer observed. According to the observation of the present inventor, this discoloration is an oxide mainly composed of copper, and is a substance mainly composed of so-called patina, and the fact that this generation can be suppressed is a factor that has improved the above problem It was guessed that. That is, this discoloration proceeds, and in the worst case, it may flow into water as a precipitate. In the present invention, it is considered that the occurrence of such inconveniences can be efficiently suppressed by removing heavy metal ions which are considered to be causative substances. This heavy metal is considered to be a heavy metal contained in the wire and the workpiece, and is likely to elute in water during processing.

  The heavy metal ion to be controlled in the present invention is preferably selected from the group consisting of copper, zinc, and iron. In particular, good results can be obtained by controlling the copper ion concentration. Specifically, the heavy metal ion concentration is set to 0.05 ppm or less. Preferably, at least the copper ion concentration is 0.05 ppm or less.

  According to a preferred embodiment of the present invention, the heavy metal ion concentration is controlled by an ion exchange resin. According to a more preferred embodiment, heavy metal ions are captured by a resin having a chelate structure. It is preferable because it captures heavy metal ions in a manner that does not release ionic species that increase the electrical conductivity of water. In particular, a resin having a chelate structure that selectively captures divalent heavy metal ions is preferable. Resins having such a chelate structure are known and commercially available, and they can be used. Specific examples thereof include a polymer having imidinoacetic acid as a chelate structure, an iminopropionic acid group and an aminophosphate group. And the like having a chelate structure.

Wire electric discharge machining apparatus and water circulation system In the method and apparatus according to the present invention, the wire electric discharge machining method and apparatus may be a known or known method and apparatus, except that the heavy metal ion concentration is controlled.

  A system in which water as a dielectric is circulated in the method and apparatus according to the present invention will be described with reference to the drawings. In FIG. 1, a processing tank 1 is a place where an electric discharge is generated between a wire and a workpiece and an operation for processing the workpiece is performed, and the processing tank 1 is filled with water, Then, the processing device 2 for compounding the workpiece is immersed. In addition, this invention is applicable not only to the aspect in which such a to-be-processed object is immersed in water but to the system which sprays water between a wire and a to-be-processed object.

  The water filled in the processing tank 1 is guided by the pump 5 from the fresh water tank 3 through the fresh water path 4. The water in the processing tank 1 is placed as a dielectric between the wire and the workpiece, and then temporarily stored in the sewage tank 7 through the sewage path 6. The water in the sewage tank 7 is returned to the fresh water tank 3 by the pump 9 through the sewage path 8. At that time, it is common to remove precipitates through the filter 10.

  The water in the fresh water tank 3 is led to a pure water purification means 11 having an ion exchange resin before the start of wire electric discharge machining, and is brought into pure water to a sufficient degree as a dielectric by contacting with the ion exchange resin. In FIG. 1, the water is guided to the pure water purification means 11 by the pump 13 through the path 12 and returns to the fresh water tank 3 through the path 14. During the electrical discharge machining, the process of pure water with the ion exchange resin may be continuously performed. If the electrical conductivity of the water in the fresh water tank 3 is monitored and a certain value is exceeded, pure water is used. It may be configured to perform a digitization process. In general, the purity is about 20 μs / cm (500,000 Ω) or more, and is usually maintained in the range of about 5 to 20 μS / cm.

  In the present invention, means for removing heavy metal ions is provided at any point in the water circulation path. For example, it can be provided at A or B in FIG. The specific configuration will be described with reference to FIGS.

  FIG. 2 shows a configuration in which the pure water purification means 11 and the heavy metal ion removal means 15 are provided in series with the water circulation path. In addition, the structure connected with the processing tank shown by FIG. 1 is abbreviate | omitted in FIG. In the figure, the heavy metal ion removing means 15 is filled with a resin having a chelate structure and capable of capturing heavy metal ions. The water in the fresh water tank 3 is first led to the heavy metal ion removing means 15 by the pump 13 through the path 12a, the heavy metal ions are removed, and then led to the pure water purification means 11 through the path 12b. Return to 3. In the present invention, the pure water purification means 11 and the heavy metal ion removal means 15 may be reversed.

  FIG. 3 shows a configuration in which the pure water purification means 11 and the heavy metal ion removal means 15 are provided in parallel with the water circulation path. In addition, the structure connected with the processing tank shown by FIG. 1 is abbreviate | omitted also in FIG. In the figure, the water in the fresh water tank 3 is guided to the heavy metal ion removing means 15 by the pump 13a through the path 12c, the heavy metal ions are removed, and returns to the fresh water tank 3 through the path 14a. On the other hand, the water in the fresh water tank 3 is led to the pure water purification means 11 through the path 12c by the pump 13b and purified, and returns to the fresh water tank 3 through the path 14a. Of course, it can also be performed by branching of the pipe with one pump 13a. 2 and 3, the ion exchange means 11 and the heavy metal ion removal means 15 are in the shape of a cylinder or tank so that only these cylinders or tanks can be removed and replaced. be able to. Thereby, the regeneration or replacement of the ion exchange resin can be easily performed by removing it.

  The present invention is further illustrated by the following examples, but the present invention is not limited to these examples.

Example 1
In a wire electric discharge machine (manufactured by FANUC: 180iS-WB) having the basic structure shown in FIG. 1, an ion exchange resin cylinder filled with a polystyrene resin having an iminodiacetic acid functional group, and an ion exchange resin for pure water purification The cylinder was installed in parallel. After operating for 3 months, the processing tank, fresh water tank, and other water flow paths were observed, and no discoloration considered to be patina was observed. When the copper ion concentration in the water in the processing tank and the fresh water tank after the operation for 3 months was measured, it was 0.07 ppm in the processing tank and below the detection limit (0.05 ppm) in the fresh water tank.

Example 2
In a wire electric discharge machine (manufactured by FANUC: 310iS-WA) having the basic structure shown in FIG. 1, an ion exchange resin cylinder filled with a polystyrene resin having an iminodiacetic acid functional group, and an ion exchange resin for pure water purification The cylinder was installed in series. After 6 months of operation, the processing tank, fresh water tank, and other water channels were observed, and no discoloration that seemed patina was observed. When the copper ion concentration in the water in the fresh water tank after 6 months of operation was measured, it was below the detection limit (0.05 ppm). In addition, the copper ion concentration in a fresh water tank when it operates for six months without installing the ion exchange resin cylinder filled with the polystyrene resin having an iminodiacetic acid functional group is 0.11 ppm. A possible discoloration was observed.

In the comparative example wire electric discharge machine (manufactured by FANUC: 16-W), the ion exchange resin cylinder for capturing heavy metal ions was not provided, but the ion exchange resin cylinder for pure water was installed and operated for 6 months. . Thereafter, when the processing tank, fresh water tank, and other water flow paths were observed, the occurrence of discoloration considered to be patina was observed. When the copper ion concentration in the water in the processing tank and fresh water tank was measured, it was 0.26 ppm in the processing tank and 0.07 ppm in the fresh water tank.

Claims (10)

A wire electric discharge machining method in which a discharge is generated between a wire and a workpiece, thereby removing a part of the workpiece and molding is performed.
A wire electric discharge machining method, wherein water from which heavy metal ions are removed is placed between the wire and the workpiece as a dielectric.   The water according to claim 1, wherein the water is placed as a dielectric between the wire and the workpiece and then circulated so as to remove heavy metal ions and again between the wire and the workpiece. Wire electric discharge machining method.   The wire electric discharge machining method according to claim 1 or 2, wherein heavy metal ions are removed by bringing the water into contact with an ion exchange resin.   The wire electric discharge machining method according to claim 3, wherein the ion exchange resin has a chelate structure capable of capturing heavy metal ions.   The wire electric discharge machining method according to any one of claims 1 to 4, wherein the heavy metal ions are ions derived from heavy metals contained in the wire or the workpiece.   The wire electric discharge machining method according to any one of claims 1 to 5, wherein the heavy metal ion is selected from the group consisting of copper, zinc, and iron. An apparatus for carrying out the wire electric discharge machining method according to any one of claims 1 to 6,
A wire electric discharge machining means for generating a discharge between the wire and the workpiece, thereby removing a part of the workpiece and forming the workpiece;
Means for placing water as a dielectric between the wire and the workpiece;
A wire electric discharge machining apparatus comprising at least heavy metal ion removing means for removing heavy metal ions from the water.   Water placed as a dielectric between the wire and the workpiece is introduced into the heavy metal ion removing means to remove heavy metal ions, and then circulated again to be placed between the wire and the workpiece. The wire electric discharge machining apparatus according to claim 7, further comprising means for causing the wire to discharge.   The wire electric discharge machining apparatus according to claim 7 or 8, wherein the heavy metal ion removing means is an ion exchange resin. The wire electric discharge machining apparatus according to any one of claims 7 to 9, wherein the ion exchange resin has a chelate structure capable of capturing heavy metal ions.

Images