WO2013077308A1

WO2013077308A1 - Electrolyte jet processing device and electrolyte jet processing method

Info

Publication number: WO2013077308A1
Application number: PCT/JP2012/080035
Authority: WO
Inventors: 国枝　正典
Original assignee: 国立大学法人東京大学
Priority date: 2011-11-22
Filing date: 2012-11-20
Publication date: 2013-05-30
Also published as: JP2013108139A; JP5871262B2

Abstract

The purpose of the present invention is to provide electrolyte jet processing technology that can be applied to fine processing, high aspect ratio processing, or deep hole processing. An electrolyte nozzle (1) discharges an electrolyte (12) toward a workpiece (W). A gas nozzle (2) sprays a gas (13) toward the workpiece (W) in a direction that is coaxial with the electrolyte (12). A power supply (3) is constituted so as to be able to make a current flow between the electrolyte and the workpiece.

Description

Electrolyte jet machining apparatus and electrolyte jet machining method

The present invention relates to a technique for performing electrolytic solution jet machining on a workpiece.

Electrolyte jet machining is a machining method in which an electrolytic solution is ejected from a nozzle toward a workpiece (so-called workpiece), and the workpiece is electrolyzed by applying a voltage using the nozzle as a cathode and the workpiece as an anode. . Since this processing method is a chemical processing method, there is an advantage that thermal processing and mechanical processing do not have, that is, a work-affected layer, residual stress, cracks, and burrs are not generated. In addition, since the machining amount is determined by the amount of electricity, there is a feature that adjustment of the gap between the workpiece and the nozzle is unnecessary (see Non-Patent Document 1 below).

In electrolyte jet machining, the water jump phenomenon occurs sufficiently away from the nozzle, resulting in a radially thin layer flow field, in which the current density is concentrated directly under the jet, and only under the jet is selectively processed. be able to.

By the way, in the case of microfabrication, since the flow rate of the electrolytic solution is small, the electrolyte jumping phenomenon may occur in the vicinity of the nozzle. In this case, a flow field of a radial thin layer cannot be obtained, and the current density distribution is diffused in the electrolytic solution accumulated in the vicinity of the nozzle, so that the processed shape is destroyed.

The following Non-Patent Document 2 shows that, for this problem, the electrolytic solution jet processing can be performed by blowing air from an air nozzle installed beside the electrolytic solution nozzle and removing the liquid reservoir of the electrolytic solution. . However, in this document, since air is blown onto the workpiece from an oblique direction, the machining phenomenon is not axially symmetric, and the machining accuracy may be reduced.

Further, in the conventional electrolytic solution jet machining, as the work of the workpiece progresses, the electrolytic solution accumulates in the processed portion, so that there is a problem that high aspect ratio machining is difficult and deep hole machining is also difficult.

The present invention has been made in response to the above-described problems. The main object of the present invention is to provide an electrolyte jet machining technique that can be used for fine machining, high aspect ratio machining, or deep hole machining.

The means for solving the above-described problems can be described as the following items.

(Item 1)
It has an electrolyte nozzle, a gas nozzle, and a power source.
The electrolyte nozzle is configured to discharge the electrolyte toward the workpiece,
The gas nozzle is configured to blow gas toward the workpiece in a direction coaxial with the electrolytic solution,
The power supply is configured to allow a current to flow between the electrolytic solution and the workpiece.

(Item 2)
The electrolyte jet machining apparatus according to claim 1, wherein the gas nozzle is configured to blow the gas toward the workpiece so as to be concentric with the electrolyte as a center.

(Item 3)
3. The electrolytic solution jet machining apparatus according to

item

1 or 2, wherein the power source is a constant current source.

(Item 4)
Item 4. The electrolyte jet machining apparatus according to any one of Items 1 to 3, comprising a plurality of sets each including the electrolyte nozzle and the gas nozzle.

(Item 5)
Item 5. The electrolyte jet machining apparatus according to any one of Items 1 to 4, wherein a plurality of the electrolyte nozzles are provided, and the gas nozzle is disposed so as to surround the plurality of electrolyte nozzles.

(Item 6)
Discharging the electrolyte toward the workpiece;
Blowing gas toward the workpiece in a direction coaxial with the electrolyte; and
An electrolyte jet machining method comprising: passing an electric current between the electrolyte and the workpiece.

According to the present invention, it is possible to provide an electrolyte jet processing technique that can cope with fine processing, high aspect ratio processing, or deep hole processing.

It is explanatory drawing which shows the whole structure of the electrolyte solution jet processing apparatus in one Embodiment of this invention. It is an enlarged view which shows the front-end | tip part of an electrolyte solution nozzle. It is an expanded sectional view which shows the detailed structure of an electrolyte solution nozzle and a gas nozzle. It is a graph which shows the current density distribution in the downward direction of an electrolyte solution nozzle. It is a photograph for demonstrating the effect of Example 1, Comprising: The figure (a) shows the example without assist gas, and the figure (b) shows the example with assist gas. It is a graph for demonstrating the improvement of the aspect-ratio in the case of using assist gas. It is explanatory drawing for demonstrating why a deep hole process is difficult when there is no assist gas. It is a graph for demonstrating the result of the deep hole process at the time of using assist gas. It is explanatory drawing for demonstrating the arrangement state of the electrolyte solution nozzle and gas nozzle in the modification 1 of this invention. It is explanatory drawing for demonstrating the arrangement state of the electrolyte solution nozzle and gas nozzle in the modification 2 of this invention. It is explanatory drawing for demonstrating the arrangement state of the electrolyte solution nozzle and gas nozzle in the modification 3 of this invention. It is explanatory drawing for demonstrating the arrangement state of the electrolyte solution nozzle and gas nozzle in the modification 4 of this invention.

Hereinafter, with reference to the accompanying drawings, an electrolytic solution jet processing apparatus (hereinafter may be abbreviated as “processing apparatus”) according to an embodiment of the present invention will be described.

(Configuration of electrolyte jet processing equipment)
As shown in FIG. 1, the processing apparatus of this embodiment includes an electrolyte nozzle 1, a gas nozzle 2, and a power source 3. The processing apparatus further includes a compressor 4, a pressure tank 5, a table 6, a machining tank 7, a processing chamber 8,

pipes

9 a and 9 b, and

regulators

10 and 11.

The electrolytic solution nozzle 1 is configured to discharge the electrolytic solution 12 sent from the pressure tank 5 through the pipe 9a toward the workpiece W (see FIGS. 2 and 3).

The gas nozzle 2 is configured to blow a gas 13 toward the workpiece W in a direction coaxial with the electrolyte 12 (see FIGS. 2 and 3). Specifically, the gas nozzle 2 is connected to the compressor 4 via the regulator 11 so that the gas from the compressor 4 can be sent out toward the workpiece W. Here, the gas nozzle 2 is configured to inject the gas 13 so as to be concentric around the jet flow of the electrolytic solution. Moreover, normal air is used as the gas 13 of this embodiment. As the gas, any gas may be used as long as it can exhibit the function of an assist gas as will be described later.

The power source 3 is configured to allow a current to flow between the electrolytic solution 12 and the workpiece W via the electrolytic solution nozzle 1. As the power source 3, a DC constant current source is used in the present embodiment. By using the constant current source, even if the gap length between the electrolyte nozzle 1 and the workpiece W varies, the machining depth to the workpiece W can be kept constant. However, it is also preferable to use a constant voltage source as the power source 3 when it is desired to increase the amount of processing as the gap length is narrow, such as when it is desired to smooth the surface irregularities. Even when a constant current source is used as the power source 3, current on / off and current value fluctuations can be controlled in synchronization with scanning of the electrolyte nozzle 1.

The compressor 4 is configured to supply compressed gas to the pressure tank 5 via the regulator 10 and the pipe 9b. Furthermore, the compressor 4 is configured to supply the compressed gas to the gas nozzle 2 via another pipe and the regulator 11.

The pressure tank 5 stores the electrolytic solution 12 and supplies the electrolytic solution 12 pressurized by the compressed gas to the electrolytic solution nozzle 1.

The table 6 is used to place the workpiece W on the upper surface.

The machining tank 7 is configured to accommodate therein the electrolytic solution 12 discharged toward the workpiece W. The machining tank 7 includes a drain portion 701 for sending out the discharged electrolyte solution 12 to the outside.

The processing chamber 8 is configured to cover the entire machining tank 7. The

regulators

10 and 11 are configured to be able to control the ejection speed of the electrolyte solution 12 and the gas 13 by regulating the flow rate of the compressed gas, respectively.

(Operation of this embodiment)
Hereinafter, the operation of this embodiment will be described.

In the present embodiment, the electrolyte 12 is sprayed from the electrolyte nozzle 1 toward the workpiece W using the pressure of the gas in the pressure tank. In the following, the electrolytic solution thus ejected may be referred to as an “electrolytic solution jet”. At that time, a voltage is applied between the electrolytic solution nozzle 1 and the workpiece W, that is, between the electrolytic solution 12 and the workpiece W, by the power source 3 to cause a current to flow. The polarity of the current is such that when the workpiece W is removed, the electrolytic solution nozzle 1 side is negative and the workpiece W side is positive, and when the electrodeposit is adhered to the surface of the workpiece W, the electrolysis The liquid nozzle 1 side is positive, and the workpiece W side is negative. Since these points can be the same as those of the already known technology, further detailed description is omitted. The processing in the present embodiment is used as a concept including both “removal of the workpiece by electrolysis” and “adhesion of the electrodeposit on the workpiece”.

Furthermore, in this embodiment, when the electrolyte solution 12 is ejected, the gas 13 is ejected from the gas nozzle 2 toward the workpiece W (see FIG. 2). Thereby, in this embodiment, the gas 13 can be injected toward the workpiece W coaxially with the injection direction of the electrolyte solution 12 and on the outer peripheral side of the electrolyte solution. In the following, the gas thus injected may be referred to as “assist gas”.

In the conventional technique described above, when the flow rate of the electrolyte jet is small, the water jumping portion is not sufficiently separated from the nozzle in the radial direction, and the thin layered flow field collapses, so that the current density cannot be concentrated directly under the jet. There was a problem that local processing could not be performed. On the other hand, according to the processing apparatus of the present embodiment, as described above, the gas 13 can be injected in the direction coaxial with the injection direction of the electrolyte solution 12, and the jumping portion can be moved downstream. Further, due to the shearing force applied to the electrolyte solution 12 by the flow of the injected gas 13, the flow rate in the radial direction of the electrolyte solution 12 (the flow rate in the direction away from the axis of the electrolyte solution nozzle 1) is increased. Thereby, the film thickness of the electrolyte solution 12 on the upper surface of the workpiece W can be reduced, and as a result, the current density distribution can be localized directly under the jet (see FIG. 4).

Example 1
When the flow rate of the electrolyte jet was small, the possibility of processing with or without assist gas was investigated. Table 1 below shows the experimental conditions. The jet flow rate was adjusted by changing the pressure in the pressure tank 5 by the regulator 10.

In this table, “Nozzle ID” is the inner diameter of the nozzle part of the electrolyte nozzle, “Gap width” is the distance between the lower end of the electrolyte nozzle 1 and the surface of the workpiece W, and “Tank Pressure” is The pressure in the pressure tank 5, “Air pressure”, is the pressure of the gas sent out from the compressor 4. In this example, SUS304 was used as a workpiece.

Fig. 5 (a) shows the state of the electrolyte when the tank pressure is 0.20 MPa and no assist gas, and Fig. 5 (b) shows the electrolyte solution when the tank pressure is 0.20 MPa and the assist gas pressure is 0.08 MPa. Show the state. From this, it can be seen that the electrolyte solution and the nozzle are in contact with each other when there is no assist gas. On the other hand, when the assist gas is used even at the same flow rate, the water jumping part moves away from the nozzle, and a thin electrolyte film can be formed. Table 2 shows the results of the stability evaluation by changing Tank Pressure and Air Pressure.

In Table 2, the symbol “◯” indicates that the electrolyte solution film was stably formed, and the symbol “x” indicates that this could not be formed.

As can be seen from this result, when the assist gas was not used, the processing could not be performed at a tank pressure of 0.20 MPa or less, but when the assist gas was used, the processing could be performed at any tank pressure. It was.

(Example 2: Improvement of aspect ratio of processed shape)
The current density distribution assumed in the processing apparatus of this example is as shown in FIG. According to this, the current density distribution also spreads in the periphery immediately below the electrolyte jet. Therefore, the diameter of the processing hole becomes larger than the inner diameter of the nozzle, and the processing accuracy tends to deteriorate.

On the other hand, according to Non-Patent Document 1, when the viscosity of the fluid is ignored, the thickness of the electrolyte immediately after the electrolyte jet collides with a flat workpiece is 1/4 of the jet diameter. However, in reality, the electrolyte and air are viscous and mutually exert a shearing force. Therefore, if the flow velocity of the thin film part is accelerated by the shearing force of the assist gas, the thickness of the electrolyte film after the collision with the workpiece can be further reduced from the continuous equation, and the current density distribution is concentrated more directly under the jet. It is thought that it can be made. Thereby, expansion of the diameter of the processing hole is suppressed, and improvement in processing accuracy can be expected. In addition, when the current is the same, it can also be expected that the processed hole will become deeper if the current density is concentrated directly under the jet. Therefore, the effect of improving the processing accuracy by assist gas was investigated by investigating the ratio (aspect ratio) of the depth to the diameter of the processed hole.

In the conditions shown in Table 3 below, drilling was performed by changing only the assist gas ejection pressure, and the aspect ratio was investigated. In Table 3, “Machining current” is a current value between the electrolyte nozzle 1 and the workpiece W. In this example, a constant current source is used as a power source. The obtained result is shown in FIG. The aspect ratio was clearly improved when the gas pressure was 0.08 MPa compared to the case without assist gas. From this, it was found that the accuracy improvement by the assist gas of the electrolytic solution jet processing is possible.

(Example 3: deep hole machining)
In the hole processing by the electrolytic solution jet, when the processing proceeds as shown in FIG. 7A to FIG. 7B, the electrolytic solution accumulates in the processed hole, and the current density distribution may be concentrated directly under the jet. In the end, only the processing of the side surface proceeds and it becomes impossible to process in the depth direction. In addition, in FIG. 7, the process direction is shown by the arrow described in the workpiece.

In contrast, if the assist gas is used, it is considered that the electrolytic solution in the processing mark can be discharged and a deeper hole can be processed than before. Therefore, machining was performed at different machining times for cases where there was no assist gas and cases where there was no assist gas, and the limit of the machining depth was investigated. The experimental conditions are shown in Table 4, and the obtained results are shown in FIG.

FIG. 8 shows that deeper holes can be machined when assist gas is used. This is thought to be because the assist gas was discharged from the electrolyte and the current density distribution could be concentrated in the depth direction of the hole instead of the side surface of the hole. However, the processing depth has reached the limit even when using assist gas. This is considered to be because when the processing depth exceeds a certain level, the electrolyte cannot be completely discharged even when the assist gas is used, and the current density cannot be concentrated directly under the jet. .

As described above, in the electrolyte jet machining of this embodiment, the machining characteristics can be improved by introducing an assist gas coaxial with the electrolyte jet. In particular, due to the effect of the assist gas, a thin electrolyte film that flows radially even when the jet flow rate is small is formed, and local processing becomes possible. In addition, the current density is concentrated only directly under the jet due to the shearing force generated by the assist gas, making it possible to perform machining with higher accuracy. Furthermore, by promoting the discharge of the electrolyte in the processed hole, it has become possible to process a deeper hole than before.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

For example, in the above-described embodiment, the workpiece is removed as the machining of the workpiece, but the electrodeposit can be attached to the workpiece by reversing the polarity of the power source.

(Modification of the present invention)
Hereinafter, an example in which the arrangement state of the electrolyte nozzle and the gas nozzle in the above-described embodiment is changed will be described with reference to FIGS. The following examples are also included in the scope of the present invention.

(Modification 1: FIG. 9)
In this example, a set composed of the electrolyte nozzle 1 and the gas nozzle 2 is densely arranged along one direction (the left-right direction in the figure). In more detail, the group comprised by the electrolyte nozzle 1 and the gas nozzle 2 is arrange | positioned in a line along the direction which cross | intersects those axial directions. Thereby, injection of electrolyte solution can be performed along a specific row. Other configurations and advantages are the same as those of the above-described embodiment.

(Modification 2: FIG. 10)
In this example, the plurality of electrolyte nozzles 1 are densely arranged along one direction (left and right direction in the figure). And the gas nozzle 2 is arrange | positioned so that these electrolyte solution nozzles 1 may be enclosed. Also in this example, the electrolyte solution can be injected along a specific row. Other configurations and advantages are the same as those of the above-described embodiment.

(Modification 3: FIG. 11)
In this example, the plurality of electrolyte nozzles 1 are arranged in a densely assembled state. And the gas nozzle 2 is arrange | positioned so that these electrolyte solution nozzles 1 may be enclosed. In this example, the electrolyte solution can be sprayed simultaneously not only at one point but also at multiple points within a specific plane. Other configurations and advantages are the same as those of the above-described embodiment.

(Modification 4: FIG. 12)
In this example, the cross-sectional shape of the electrolytic solution nozzle 1 is not circular but rectangular. A gas nozzle 2 having a substantially similar cross-sectional shape is disposed so as to surround the electrolytic solution nozzle 1. In this example, an electrolytic solution having a certain width can be injected. Other configurations and advantages are the same as those of the above-described embodiment.

Claims

It has an electrolyte nozzle, a gas nozzle, and a power source.
The electrolyte nozzle is configured to discharge the electrolyte toward the workpiece,
The gas nozzle is configured to blow gas toward the workpiece in a direction coaxial with the electrolytic solution,
The power supply is configured to allow a current to flow between the electrolytic solution and the workpiece.
The electrolyte jet machining apparatus according to claim 1, wherein the gas nozzle is configured to blow the gas toward the workpiece so as to be concentric with the electrolyte as a center.
The electrolyte jet machining apparatus according to claim 1 or 2, wherein the power source is a constant current source.
The electrolytic solution jet machining apparatus according to any one of claims 1 to 3, comprising a plurality of sets each including the electrolytic solution nozzle and the gas nozzle.
The electrolyte jet machining apparatus according to any one of claims 1 to 4, further comprising a plurality of the electrolyte nozzles, wherein the gas nozzle is disposed so as to surround the plurality of electrolyte nozzles.
Discharging the electrolyte toward the workpiece;
Blowing gas toward the workpiece in a direction coaxial with the electrolyte; and
An electrolyte jet machining method comprising: passing an electric current between the electrolyte and the workpiece.