Patent Application
20180029151
The present invention relates to an electrochemical machining device and electrochemical machining method.
Electrolyte jet machining (refer to non-patent publication 1 and patent publications 1 and 2 below) is known as one type of electrochemical machining. Electrolyte jet machining is a method for selectively machining only directly below jet flow of an electrolyte, by discharging electrolyte from a nozzle and applying a voltage to a gap between the nozzle and a workpiece. In this case, the nozzle acts as a tool electrode. At the time of electrochemical machining, a voltage is applied between electrodes so that a workpiece becomes an anode, and electric current flows via an electrolytic solution. This machining method has the advantage that since the machining principle is electrolytic action, which is a chemical reaction, it is possible to machine a workpiece regardless of hardness as long as it is a conductive material, and affected layers or residual stress, burrs and cracks etc. do not arise. It is also possible to perform maskless machining of an arbitrary shape by scanning a nozzle.
The present inventors have heretofore disclosed obtaining a mirror surface of small surface roughness under high current density, and obtaining complex porous properties under low current density, by controlling current density, using SUS304 as a workpiece material (non-patent publication 2 below). With the machining method disclosed in these publications, surface roughness of a workpiece is deteriorated due to passage of a low current density region as a result of scanning.
The present inventors have therefore disclosed being able to perform mirror finishing in an arbitrary shape by scanning a nozzle (tool electrode) at high speed and through multiple reciprocations (non-patent publication 3 below).
However, generally, in the case of machining complex shapes, in order to scan an electrode a plurality of times at high speed considerable device cost and running cost become necessary. Also, in the case of carrying out high speed scanning, a problem arises in that the electrolytic solution flies out due to movement of the electrode.
It should be noted that non-patent publication 4 below shows attempts to achieve machining precision through the use of electrochemical machining using ultrashort pulse current that utilizes formation of an electrical double layer on an electrode surface.
Non-Patent Document 1
Non-Patent Document 2
Non-Patent Document 3
Non-Patent Document 4
The present disclosure has been conceived in view of the above-described situation. The disclosure provides technology that can improve roughness of a machined surface while keeping the relative scanning speed of a tool electrode with respect to a workpiece low.
Means for solving the above described problems can be as disclosed in any of the following aspects.
(Aspect 1)
An electrochemical machining device for machining a surface of a workpiece using electrochemical machining, comprising a power source, a tool electrode, an electrolytic solution supply section, and a charge control means. The power source applies a voltage, for making current for electrochemical machining flow, between the tool electrode and the workpiece. The tool electrode is arranged apart from the workpiece and is capable of being scanned relatively along a surface direction of the workpiece. The electrolytic solution supply section can supply electrolytic solution for electrochemical machining between the tool electrode and the workpiece. The charge control means eliminates an electrical charge that has accumulated between the tool electrode and the workpiece as a result of voltage application from the power source.
(Aspect 2)
The electrochemical machining device of aspect 1, wherein the power source uses pulse current as the current, and the charge control means eliminates the electrical charge based on a duty factor of the pulse current.
(Aspect 3)
The electrochemical machining device of aspect 2, wherein an upper limit of an absolute value of a pulse width for the pulse current is set short enough to apply mirror finishing to a surface of the workpiece, and a current density of the current for electrochemical machining is set high enough for application of the mirror finishing.
(Aspect 4)
The electrochemical machining device of aspect 1, wherein the power source uses alternating current as the current, and the alternating current has a forward direction current component that makes the workpiece an anode and a reverse direction current component that makes the workpiece a cathode, and the charge control means eliminates the electrical charge by applying the reverse direction current component.
(Aspect 5)
The electrochemical machining device of aspect 4, wherein the charge control means controls the power source so that a value obtained by integrating a forward direction current density of the forward direction current component over and application time, and a value obtained by integrating a reverse current density of the reverse direction current component over an application time, become substantially equal.
(Aspect 6)
The electrochemical machining device of aspect 5, wherein the charge control means sets a peak value for the reverse direction current component lower than a peak value for the forward direction current component.
(Aspect 7)
The electrochemical machining device of any one of aspects 4-6, wherein the charge control means eliminates the electrical charge by inserting a current idle period between the forward direction current component and the reverse direction current component of the alternating current.
(Aspect 8)
The electrochemical machining device of any one of aspects 4-7, wherein the tool electrode is made from monocrystalline silicon, a titanium alloy, a niobium alloy, graphite, or platinum.
(Aspect 9)
The electrochemical machining device of any one of aspects 1-8, wherein the power source is a constant voltage source or a constant current source.
(Aspect 10)
The electrochemical machining device of any one of aspects 1-9, wherein at least part of a surface of the workpiece has a curvature that is not 0, and an opposing area of the workpiece and the tool electrode is made small enough, within a range of the opposing area, to be able to regard distribution of distance between the tool electrode and the workpiece as substantially constant regardless of the curvature.
(Aspect 11)
The electrochemical machining device of any one of aspects 1-10, wherein the charge control means a changes content of control for eliminating the electrical charge in accordance with relative scanning of the tool electrode.
(Aspect 12)
An electrochemical machining method that uses the electrochemical machining device of any one of aspects 1-11 comprising a step of making a current for electrochemical machining flow between the tool electrode and the workpiece using the power source, a step of scanning the tool electrode relatively along the surface direction of the workpiece, a step of supplying electrolytic solution between the tool electrode and the workpiece using the electrolytic solution supply section, and a step of eliminating the electrical charge that has accumulated between the tool electrode and the workpiece using the charge control means.
(Aspect 13)
A surface roughness adjustment method that uses the electrochemical machining device of any one of aspects 1-11 comprising a step of making a current for electrochemical machining flow between the tool electrode and the workpiece using the power source, a step of scanning the tool electrode relatively along the surface direction of the workpiece, a step of supplying electrolytic solution between the tool electrode and the workpiece using the electrolytic solution supply section, and a step of adjusting surface roughness of the workpiece surface by controlling the electrical charge that has accumulated between the tool electrode and the workpiece using the charge control means.
(Aspect 14)
An electrochemical machining device, comprising a tool electrode arranged apart from the workpiece, an electrolytic solution that fills a gap between the workpiece and the tool electrode, and a power source that supplies forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece, a peak value of the reverse direction current pulses is made lower than a peak value of the forward direction current pulses, and a pulse width of the reverse direction current pulses is set wider than a pulse width of the forward direction current pulses.
(Aspect 15)
An electrochemical machining device, comprising a tool electrode arranged apart from the workpiece, an electrolytic solution that fills a gap between the workpiece and the tool electrode, and a power source that supplies forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece, a peak value of the reverse direction current pulses is made higher than a peak value of the forward direction current pulses, and a pulse width of the reverse direction current pulses is set narrower than a pulse width of the forward direction current pulses.
(Aspect 16)
An electrochemical machining device, comprising a tool electrode arranged apart from the workpiece, an electrolytic solution that fills a gap between the workpiece and the tool electrode, and a power source that supplies forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece, a pulse width of the reverse direction current pulses is set to less than or equal to a pulse width of the forward direction current pulses, and when switching from the reverse direction current pulses to the forward direction current pulses, an idle period is provided.
(Aspect 17)
An electrochemical machining device, comprising a tool electrode arranged apart from the workpiece, an electrolytic solution that fills a gap between the workpiece and the tool electrode, and a power source that supplies forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece, with respect to a forward direction electrical charge that is supplied between the workpiece and the tool electrode by the forward direction current pulses, a reverse direction electrical charge that is supplied between the workpiece and the tool electrode by the reverse direction current pulses is set so as to become smaller, and when switching from the reverse direction current pulses to the forward direction current pulses, an idle period is provided.
(Aspect 18)
An electrochemical machining device, comprising a tool electrode arranged apart from the workpiece, an electrolytic solution that fills a gap between the workpiece and the tool electrode, and a power source that supplies forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece, a ratio (A/B) of a forward direction electrical charge (A) that is supplied between the workpiece and the tool electrode by the forward direction current pulses, and a reverse direction electrical charge (B) that is supplied between the workpiece and the tool electrode by the reverse direction current pulses, is set so as to become larger, as speed of the scanning becomes faster.
(Aspect 19)
An electrochemical machining device, comprising a tool electrode arranged apart from the workpiece, an electrolytic solution that fills a gap between the workpiece and the tool electrode, and a power source that supplies forward direction current pulses between the workpiece and the tool electrode, wherein in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece, a duty factor for applying the forward direction current pulses is set so as to become larger, as speed of the scanning becomes faster.
(Aspect 20)
An electrochemical machining device, comprising a tool electrode arranged apart from the workpiece, an electrolytic solution that fills the gap between the workpiece and the tool electrode, and a power source for supplying forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece, a pulse width of the reverse direction current pulses is set so as to become smaller with respect to a pulse width of the forward direction current pulses, as speed of the scanning becomes faster.
According to the present disclosure, it is possible to improve the roughness of a machined surface while keeping a relative scanning speed of a tool electrode, with respect to a workpiece, low.
In the following, an electrochemical machining device (hereafter sometimes referred to as “machining device”) of a first embodiment of the present disclosure will be described with reference to the attached drawings. The machining device of this embodiment is for machining a workpiece 1 (refer to
The machining device of this embodiment comprises a power source 10, a tool electrode 20, an electrolytic solution supply section 30 and charge control means 40 as basic elements (refer to
(Power Source)
The power source 10 applies a voltage, for making current for electrochemical machining flow, between the tool electrode 20 and a workpiece 1. In more detail, one electrode of the power source 10 is electrically connected to the tool electrode 20, another electrode of the power source 10 is electrically connected to the workpiece 1, and it is possible to apply a given voltage between the two.
The power source 10 of this embodiment uses a pulse waveform voltage (pulse voltage) as a voltage to be applied, and in this way it is possible to make current having a pulse waveform (refer to practical examples 1 and 2 which will be described later) flow between the electrodes. It should be noted that with this embodiment, as the power source 10, a constant current source that makes a current value that has been designated by the charge control means 40 flow between electrodes is used, but a constant voltage source may also be used as long as the necessary current value can be obtained. It is also possible to use a so-called high-speed bipolar power source, for example, as the power source 10 of this embodiment.
In the power source 10 of this embodiment, an upper limit of an absolute value for the pulse width of the pulse current is set small enough that a mirror finishing can be applied to a surface of the workpiece 1. Also, a lower limit for the current density is set to a value at which machining marks are finished to a mirror surface while the tool electrode is at rest. What level of current density and pulse width should be set to make it possible to accomplish mirror finishing can be determined by experimentation, for example. Here, the current density is obtained by dividing electrical current by an opposing area of the tool electrode and the workpiece. Also, the mirror finishing is machining that makes surface roughness small, for example, machining to make surface roughness Rz 0.3 μm or less. An upper limit for the absolute value of the pulse width is, for example, 150 μs to 100 μs. However, the present disclosure is not limited to these numerical values.
(Tool Electrode)
The tool electrode 20 is arranged apart from the workpiece 1, and is capable of being scanned relatively along a surface direction of the workpiece 1. Specifically, the tool electrode 20 of this example is provided with a base portion 21 and a tip portion 22.
The base portion 21 is formed with a hollow cylindrical shape, and connected to piping 32 (described later) of the electrolytic solution supply section 30 which is constructed so as to feed electrolytic solution to the tip portion 22.
The tip portion 22 extends from a tip side of the base portion 21 in the direction of the workpiece 1 (downward direction in
As material for the tool electrode 20, various materials can be used as long as it is conductive, and has the necessary mechanical strength. In particular, in a case where monocrystalline silicon, a titanium alloy, a niobium alloy, graphite or platinum has been used as the material for the tool electrode 20, these materials are suitable since they are difficult to electrolyze even if a reverse direction voltage (voltage that makes the workpiece a cathode) is applied.
Here, in a case where at least part of the surface of the workpiece 1 has a curvature that is not 0, an opposing area of the workpiece 1 and the tool electrode 20 is preferably sufficiently small that the distance between the tool electrode 20 and the workpiece 1 within this opposing area is effectively uniform regardless of the curvature. If this is done, it is possible to apply appropriate mirror finishing even to a workpiece having a non-flat surface to be machined, by scanning the machined surface. Making the distance between the workpiece 1 and the tool electrode 20 constant, and sufficiently narrow (for example, making a gap of 1 mm or less, more preferably 0.5 mm or less) is preferable for the realization of mirror finishing. Accordingly, using a tool electrode 20 that has a small opposing area like this contributes to satisfying these gap conditions.
(Electrolytic Solution Supply Section)
The electrolytic solution supply section 30 can supply electrolytic solution for electrochemical machining between the tip portion 22 of the tool electrode 20 and the surface to be machined of the workpiece 1 (upper surface in
The tank 31 is a section for accumulating the electrolytic solution 3 for electrochemical machining. Here, it is possible to use various fluids that are normally used for electrochemical machining as the electrolytic solution 3.
The piping 32 connects between the tank 31 and the base portion 21 of the tool electrode 20. The pump 33 is attached at some point along the piping 32, and can feed the electrolytic solution 3 to the tool electrode 20 in an appropriate flow amount. With this embodiment, in order to obtain an accurate flow amount, a so-called gear pump has been used as the pump 33, but this is not restrictive.
The sink 34 is a section that temporarily holds electrolytic solution that has been supplied towards the workpiece 1. A drain section 341 for discharging the electrolytic solution 3 that has been supplied is formed in the sink 34. The electrolytic solution 3 that has been discharged from the sink 34 is recovered using an appropriate method that is not illustrated.
(Charge Control Means)
The charge control means 40 is a functional element for eliminating electrical charge that has accumulated between the tool electrode 20 and the workpiece 1 as a result of voltage application from the power source 10. More specifically, the charge control means 40 of this embodiment is implemented as a controller (for example, a function generator) configured to adjust a current waveform (for example, current pulse width, peak value, pulse frequency etc.) attributable to voltage from the power source 10. As an actual device structure, the charge control means 40 may be part of the functions within the power source 10. Basically, the charge control means is not restricted to a mechanical structure as long as it is capable of exhibiting the necessary functions, and can also be implemented, for example, using a combination of a computer and computer programs, and does not need to exist as a single element.
The charge control means 40 of this embodiment is configured to eliminate an electrical charge that has accumulated between the electrodes based on a duty factor of pulse current. Detailed operation of the charge control means 40 (specifically a current waveform) will be described later using practical examples 1 and 2.
(Workpiece Support Section)
The workpiece support section 50 supports the workpiece 1 which constitutes the object of the electrochemical machining, and with this embodiment is constructed using a machining table.
(Scanning Drive Section)
The scanning drive section 60 comprises an XZ direction drive section 61 and a Y direction drive section 62 with this embodiment. The XZ direction drive section 61 can move the tool electrode 20 at a given speed in an X direction (left to right direction in
Operation of the machining device of the previously-described first embodiment will be described in the following.
(Description of Machining Principle)
As a prerequisite for operation description, the machining principle of the electrochemical machining of this embodiment will be described with further reference to
With machining that scans a tool electrode (scanning machining), when directly beneath a nozzle of high current density that passes a point on the workpiece, if that current density is sufficiently high that a mirror surface can be obtained when the nozzle is at rest, the workpiece surface directly beneath the nozzle is machined to a mirror surface. However, after that, a peripheral section thereof with low current density passes through that machining portion. In a case where the scanning speed is slow, the workpiece surface is roughened by electrochemical machining due to the peripheral section with low current density, and surface roughness becomes large (that is, from the perspective aimed at mirror finishing, the mirror surface is degraded).
However, a machining amount per unit time in the case of low current density is significantly inferior compared to the case of high current density. If scanning speed is raised, the sojourn time of the electrolytic solution jet for a single scan (namely the duration for which electrochemical machining using the opposed electrode is carried out) becomes short, and the effect of the low current region becomes small. As a result, it can be considered that surface roughness improves with an increase in scanning speed, as disclosed in previously-described nonpatent publication 3.
On the other hand, in recent years, for the purpose of improving machining precision, electrochemical machining has been carried out using an ultrashort pulse current that utilizes formation of an electrical double layer on an electrode surface (previously-described non-patent publication 4). If a voltage is applied between the workpiece 1 and the tool electrode 20, an electrical double layer having a form that confronts positive and negative electrical charge is formed on the workpiece surface, as shown in
According to the findings of the present inventors, an electrolytic reaction does not occur if an electrical double layer is not sufficiently formed. Before an electrical double layer is formed at a low current density portion, elution of the workpiece is confined to a high current density portion directly below the tool electrode by turning off pulse current (namely, turning off machining voltage). Electrical charge of the electrical double layer is then discharged in an idle period after a pulse has been turned off, and the next pulse is applied. At this time, if the idle time is not sufficient, the electrical charge of the electrical double layer will not be completely discharged, and an electrolytic reaction will occur even in a low current density region. Accordingly, by making machining current short pulses and providing a sufficient idle time, it is possible to confine elution of the workpiece to only a high current density region, and even in cases of scanning at low speed it should be possible to obtain a machining surface having a good surface roughness. To give further information, if current density so as not to be able to obtain a mirror surface at the time the tool electrode is at rest is provisionally known, it is preferable to set a time for which a workpiece is exposed to that type of low current density region to short pulse width machining current when an electrode has been scanned, so as to be shorter than a time in which machining at that low current density will occur.
The above is the machining principle that is the prerequisite for this embodiment, based on the findings of the present inventors.
(Electrochemical Machining Operation)
In the case of carrying out electrochemical machining using the machining device of this embodiment, first of all the workpiece 1 is arranged on an upper surface of the workpiece support section 50 (refer to
Further, with this embodiment the tool electrode 20 is scanned relatively within an XY plane with respect to the workpiece 1 using the scanning drive section 60. In this way the surface of the workpiece 1 is machined in the scanning direction, and it is possible to improve the surface roughness. It should be noted that, with this embodiment, a Z direction position of the tool electrode 20 is fixed during machining, and is adjusted as required.
In the following, the electrochemical machining operation of this example will be described in more detail with reference to a specific practical example.
Based on the previously-described machining principle, electrochemical machining is carried out for conditions (Pulse) in table 1 below, using the device structure of the first embodiment.
The meaning of the items shown in this table is shown below. It should be noted that for reference one example of a current waveform based on a pulse voltage applied from the power source is shown in
Pulse on time [μs]: Machining current application time (t1 in
Duty factor [%]: Duty factor (t1/T in
Machining current [A]: current flowing between electrodes;
Current density [A/cm2]: current density between electrodes;
Gap width [mm]: distance between the tool electrode and the workpiece;
Flow rate [ml/s]: flow rate of electrolytic solution;
Nozzle inner diameter [mm]: inner diameter of nozzle of tip portion of tool electrode;
Electrolyte: electrolytic solution.
Current density between the electrodes is not uniform, but in the previous description, a current density value was obtained by dividing the machining current value by the internal area of the nozzle vent, for the sake of simplicity. As will be understood, the descriptions in table 1 are merely one example, and other appropriate structures are possible.
With practical example 1, pulse current is used. Pulse width t1 is made a constant value such a 100 μs, and grooving is carried out on the workpiece 1 by scanning the tool electrode 20 while varying pulse idle time t2 and scanning speed. Reference numeral T in
Measurement results for surface roughness when the scanning speed was varied are shown in
Accordingly, according to practical example 1, it is possible to eliminate the electrical charge between the electrodes using the charge control means 40, and in this way it will be understood that it is possible to improve the surface roughness of the machined surface while keeping the scanning speed low. It is also possible to control the surface roughness of the machined surface by adjusting the duty factor using the charge control means 40.
After changing the voltage waveform to be applied (namely the current waveform flowing between electrodes) to that shown in
In a case where a unipolar pulse current is used, such as in practical example 1, in order to obtain a mirror surface with low speed scanning it is necessary to lengthen the idle time (refer to
With practical example 2, by using alternating current as described previously, the polarity of current flowing between the electrodes is reversed and a time t3 exists where the workpiece becomes a cathode. During this time t3, it is possible to forcibly discharge the electrical charge that has been charged into an electrical double layer (refer to capacitor CDL in
In this example, it can be considered that mirror finishing will become possible, without setting a long idle time, by using an alternating current waveform. With this practical example 2, therefore, the pulse width t1 to make the workpiece 1 an anode was made constant at 100 μs, and the time t3 to make the workpiece 1 a cathode, and the scanning speed, were varied, and the effect of the AC current duty factor and scanning speed on the surface roughness was investigated.
Experimental results for practical example 2 are shown in
It should be noted that with practical example 2 a rectangular wave has been used for the alternating current, but it is also possible to use a different waveform, such as a triangular wave or a sine wave (
Also, with this practical example, the charge control means 40 preferably controls output from the power source 10 so that a value obtained by integrating the forward direction current with respect to the application time of that current (t1 in
Further, with this practical example the charge control means 40 preferably sets a peak value for the reverse direction current component lower than a peak value for the forward direction current component. This is because, generally, if current density is low a proportion of current that is used in removing material on the anode is reduced, and to the extent of that reduction a proportion that is used in oxygen generation and oxidation reactions is increased. In this way it is possible to reduce the amount of electrolysis of the tool electrode 20 when the reverse direction current flows, and to reduce the running cost of the device.
In a case where the peak value of the reverse direction current component is set lower than the peak value of the forward direction current component, it is preferable to set the reverse direction current pulse width longer than the forward direction current pulse width in order to sufficiently discharge the electrical charge that has been charged in to the electrical double layer. In this way it is possible to increase machining speed to the maximum limit in a range that does not cause unnecessary electrolysis at the tool electrode 20. Obviously, as has been described above, discharging the electrical charge of the electrical double layer is an objective purpose, and accumulating the electrical charge of a reverse polarity in the electrical double layer is not the purpose in this embodiment. It is therefore preferable to set the pulse width to an upper limit value without the reverse direction electrical charge exceeding the forward direction electrical charge.
With this practical example, the charge control means 40 may insert a current idle period between the forward direction current component and the reverse direction current component of the alternating current. The current idle period is capable of being inserted during period t1 in
While the reverse direction pulse width (period t3) is preferably set to level such that the reverse direction electrical charge does not exceed the forward direction electrical charge, these phenomena have variations depending on the state of the electrode gap. For example, the potential distribution in
Specifically, the reverse direction current is applied after the forward direction current is applied, and after the current idle period has been provided, the forward direction current is applied as the next cycle. Reverse direction pulse width (period t3) at this time is set so that the reverse direction electrical charge becomes about, for example, ⅔ of the forward direction electrical charge, and after that the current idle period is provided. In this way, even if local dispersion is considered, the reverse direction electrical charge does not exceed the forward direction electrical charge, and it is possible to avoid reverse charging into the electrical double layer. Also, compared to practical example 1 where only a simple current idle period was inserted, in a case where means for applying a reverse direction current is adopted, since it is possible to eliminate the electrical charge of the electrical double layer at high-speed, it is possible to carry out electrochemical machining at a high speed while acquiring a mirror surface.
While it is desirable to have a low current peak value since the reverse direction current depletes an electrode, it is possible to alleviate or eliminate a problem such as electrode electrolysis as long as the reverse direction pulse width is sufficiently short even with the reverse direction current peak value being set high. Since it is possible to eliminate an electrical charge that has been accumulated in the electrical double layer at an early stage by setting the peak value of the reverse direction current component higher than the peak value of the forward direction current component, it is possible for the reverse direction pulse width (period t3) to be set short. Specifically, since it is possible to increase the duty factor while preventing electrode consumption, it is possible to improve the machining speed. It is obviously also possible to set the current idle period after applying reverse direction current pulses, as described above.
In the first embodiment described above, the opposing area of the workpiece 1 and the tool electrode 20 preferably fully covers a surface area of the workpiece 1 to be machined over a fine section span by scanning, and preferably also makes a distance between the tool electrode and the workpiece, within the range of the opposing area, small enough that there is no significant lack of uniformity due to the curvature of the workpiece.
Also, the charge control means 40 of the first embodiment can be configured to change control content (i.e., change the content of control instructions) in order to eliminate the electrical charge, in accordance with scanning of the tool electrode 20. For example, by changing the control content in order to eliminate the electrical charge in accordance with machining conditions such as distance between electrodes, opposed area of the tool electrode and the workpiece, electrolytic solution supply amount, etc., it is possible to carry out more appropriate mirror finishing. Also, by using conditions that are contrary to appropriate conditions for mirror finishing, it is possible to form a partially non-mirrored surface.
With this embodiment, the tool electrode 20 is scanned. In a case where reciprocating motion is repeated and machining direction is changed, the relative speed between the tool electrode 20 and the workpiece 1 is lowered at locations where scanning is turned around and the locations where machining direction has been changed. Specifically, since scanning speed on the horizontal axis of
Next, an electrochemical machining device of a second embodiment of the present disclosure will be described with reference to
In the previously-described first embodiment so-called electrolyte jet machining was used. Conversely, with the second embodiment a jet is not used and normal electrochemical machining is assumed.
With the machining device of the second embodiment, a rod shaped tool electrode 220 is used instead of the nozzle shaped tool electrode 20 (refer to
The tool electrode 220 of this embodiment is arranged so as to be substantially parallel to the surface of the workpiece 1, and is capable of scanning along the surface of the workpiece 1. The electrolytic solution (not illustrated) in the second embodiment is previously filled between the tool electrode 220 and the surface of the workpiece 1 using a suitable electrolytic bath (not illustrated).
Specifically, the workpiece 1 is machined in a state of being immersed in electrolytic solution. Obviously, since it is assumed that erosion products will arise between the workpiece 1 and the tool electrode 220, electrolytic solution may also be supplied to the electrode gap using suitable blowing means. Being parallel to the workpiece 1 and the tool electrode 220 is preferable. If the distance between electrodes varies in the vertical direction it becomes difficult to implement uniform electrochemical machining. For this reason the tool electrode 220 is held and electrically connected at upper and lower parts by fixtures 221, so that it is difficult for vibration and deformation of the tool electrode 220 to happen. However, this is not at all limiting, and the tool electrode 220 may be held by only one of the upper and lower fixtures 221.
Furthermore, it is also possible to use a wire electrode that is used in a so-called wire electric discharge machine as the tool electrode 220. In order to achieve compatibility with a wire electric discharge machine, it is possible for a wire electrode to be used in the both machining actions. For example, after performing wire electric discharge machining on the workpiece 1 and then finishing the surface, it is possible to perform further finishing on the finished machined surface after electric discharge machining, with electrochemical machining using the same wire electrode. By having a structure with which it is possible to switch between wire electric discharge machining and electrochemical machining within the same device, there is the advantage that work involved in positioning the tool electrode 220 and the workpiece 1 parallel to each other becomes easy.
With the second embodiment also, similar to the previously-described first embodiment, there is the advantage that it is possible to carry out mirror finishing of the workpiece while reducing the scanning speed, by eliminating the electrical charge of the electrical double layer using the charge control means 40. Also, by using alternating current it is possible to expect improvements in the machining speed of the electrochemical machining.
The remaining structure and advantages of second embodiment are the same as those of the previously-described first embodiment, and so further description will be omitted.
Next, an electrochemical machining device of a second embodiment of the present disclosure will be described with reference to
With the third embodiment, similar to the previously-described second embodiment, a jet is not used and normal electrochemical machining is assumed.
With the machining device of the third embodiment, a block-shaped tool electrode 320 is used instead of the nozzle-shaped tool electrode 20 (refer to
The tool electrode 320 of this embodiment can be scanned along the surface of the workpiece 1 with the surface of the tool electrode 320 facing the workpiece 1. The electrolytic solution of the third embodiment is supplied between the tool electrode 320 and the workpiece 1 by a nozzle 36.
With the third embodiment also, similar to the previously-described first embodiment, there is the advantage that it is possible to carry out mirror finishing of the workpiece while reducing the scanning speed, by eliminating the electrical charge of the electrical double layer using the charge control means 40. Also, by using alternating current it is possible to expect improvements in the machining speed of the electrochemical machining.
The remaining structure and advantages of third embodiment are the same as those of the previously-described first embodiment, and so further description will be omitted.
It should be noted that the present disclosure is not limited to the previously-described embodiments, and various modifications can be additionally obtained within a scope that does not depart from the gist of the present disclosure.
(Additions)
The invention(s) described in each of the previously-described embodiments can be considered to be described in the following aspects.
(Aspect A)
An electrochemical machining device, comprising:
a tool electrode arranged apart from a workpiece,
an electrolytic solution that is filled between the workpiece and the tool electrode, and
a power source for supplying forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein
in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece,
a peak value of the reverse direction current pulses is made lower than a peak value of the forward direction current pulses, and a pulse width of the reverse direction current pulses is set wider than a pulse width of the forward direction current pulses.
(Aspect B)
An electrochemical machining device, comprising:
a tool electrode arranged apart from a workpiece,
an electrolytic solution that fills the gap between the workpiece and the tool electrode, and
a power source for supplying forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein
in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece,
a peak value of the reverse direction current pulses is made higher than a peak value of the forward direction current pulses, and
a pulse width of the reverse direction current pulses is set narrower than a pulse width of the forward direction current pulses.
(Aspect C)
An electrochemical machining device, comprising:
a tool electrode arranged apart from a workpiece,
an electrolytic solution that fills the gap between the workpiece and the tool electrode, and
a power source for supplying forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein
in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece,
a pulse width of the reverse direction current pulses is set to less than or equal to a pulse width of the forward direction current pulses, and
when switching from the reverse direction current pulses to the forward direction current pulses, an idle period is provided.
(Aspect D)
An electrochemical machining device, comprising:
a tool electrode arranged apart from a workpiece,
an electrolytic solution that fills the gap between the workpiece and the tool electrode, and
a power source for supplying forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein
in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece,
with respect to a forward direction electrical charge that is supplied between the workpiece and the tool electrode by the forward direction current pulses, a reverse direction electrical charge that is supplied between the workpiece and the tool electrode by the reverse direction current pulses is set so as to become small, and
when switching from the reverse direction current pulses to the forward direction current pulses, an idle period is provided.
(Aspect E)
An electrochemical machining device, comprising;
a tool electrode arranged apart from a workpiece,
an electrolytic solution that fills the gap between the workpiece and the tool electrode, and
a power source for supplying forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein
in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece,
a ratio (A/B) of a forward direction electrical charge (A) that is supplied between the workpiece and the tool electrode by the forward direction current pulses, and a reverse direction electrical charge (B) that is supplied between the workpiece and the tool electrode by the reverse direction current pulses, is set so as to become bigger as the speed of the scanning becomes faster.
(Aspect F)
An electrochemical machining device, comprising:
a tool electrode arranged apart from the workpiece,
an electrolytic solution that fills the gap between the workpiece and the tool electrode, and
a power source for supplying forward direction current pulses between the workpiece and the tool electrode, wherein
in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece, a duty factor for applying the forward direction current pulses is set so as to become larger as the speed of the scanning becomes faster.
(Aspect G)
An electrochemical machining device, comprising:
a tool electrode arranged apart from a workpiece,
an electrolytic solution that fills the gap between the workpiece and the tool electrode, and
a power source for supplying forward direction current pulses and reverse direction current pulses between the workpiece and the tool electrode, wherein
in the electrochemical machining device that carries out electrochemical machining by relatively scanning the tool electrode and the workpiece, a pulse width of the reverse direction current pulses is set so as to become smaller, with respect to a pulse width of the forward direction current pulses, as the speed of the scanning becomes faster.
The various embodiments described above can be combined to provide further embodiments. All of the foreign patents, foreign patent applications, and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments.
These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-037547 | Feb 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/055802 | 2/26/2016 | WO | 00 |
