JPH0265921A - Finishing working through electrolytic working - Google Patents

Abstract

PURPOSE:To finish a work, keeping the working gap between an electrode and the work constant over the whole worked surface region, by raising the electrode by a prescribed distance after the supply of the pulse electric current and spreading the gap between the electrode and the work and removing the electrolytic products, etc. in the gap by jetting an electrolytic liquid into the expanded gap and lowering the electrode by a prescribed distance and resetting the electrode at a prescribed position. CONSTITUTION:The pulse electric current is supplied into between an electrode and a work 4 which are oppositely installed, keeping a prescribed gap, through an electrolytic solution in standstill state, by an electric power source device 8, and after the pulse electric current is cut off, the electrode 2 is raised by a prescribed distance through a conversion part 7 by a drive part 6 on the basis of the instruction supplied from a controller 12, and the gap is increased. Further, a fresh electrolytic liquid is jetted between the expanded gap, and the electrolytic products, etc. in the gap are removed. Then, the electrode 2 is lowered by a prescribed distance, and reset at a prescribed position, and a work 1 can be finishing-worked, maintaining the working gap always at a constant value over the whole worked surface regions of the work 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a finishing method using electrolytic machining, and in particular, a method for finishing a three-dimensional workpiece in a short time and with high precision.
The present invention relates to a finishing method using electrolytic processing that provides a mirror-like glossy surface.

[Prior Art] Conventionally, an electrolytic processing method is known as a metal processing method. In this electrolytic processing method, an electrolytic solution such as sodium nitrate or sodium chloride is placed in the gap between the electrode and the workpiece, and while the electrode is being fed by a servo mechanism, a direct current is passed from the workpiece to the electrode, and the electrolyte in the gap is removed. It is processed by flowing at high speed to remove electrolytic products that inhibit stable electrolytic action, such as eluted metal compounds, metal ions, and hydrogen gas. (Refer to Japanese Patent Publication No. 53-18760.) [Problems to be Solved by the Invention] However, in this electrolytic processing method, it is particularly difficult to process a three-dimensional bottomed structure (a three-dimensional structure formed in a concave shape). It is impossible to maintain the machining gap between the electrode and the workpiece constant over the entire machining surface of the workpiece. The flow path resistance of the gap changes depending on the degree of curvature of the processed surface of the workpiece in its original shape, making it impossible to flow the electrolytic solution into the gap at a similar flow rate.

Therefore, the machining gap between the electrode and the workpiece changes partially on the machining surface of the workpiece, especially in the direction perpendicular to the electrode feeding direction, and the removal of electrolytic products generated in the gap differs depending on the position. It is difficult to accurately transfer the electrode to the workpiece due to differences in the progress of the polishing process, and if you want to obtain a high-precision surface quality such as a glossy surface, another polishing process is required. The disadvantage is that it takes a lot of time and effort. Also,
The disadvantage is that the servo mechanism for sending the electrodes is complicated and costs increase.

Therefore, the purpose of this invention is to be able to maintain a constant machining gap with the electrode over the entire machining surface of a workpiece, and to obtain highly accurate surface quality such as a mirror-like glossy surface in a short time. The goal is to realize a finishing method using electrolytic processing.

[Means for Solving the Problems] To achieve this object, the present invention provides a method for finishing a workpiece by supplying a pulsed current between electrodes and a workpiece disposed opposite each other in a static electrolyte. , a step of setting the electrode at a predetermined position so that the electrode and the workpiece are arranged facing each other with a predetermined gap; a step of raising the electrode by a predetermined distance (L) after supplying the pulse current to enlarge the gap between the electrode and the workpiece; A step of ejecting electrolyte into the enlarged gap to eliminate electrolytic products, etc. in the gap, and a step of moving the electrode a predetermined distance (L).
) lowering and resetting to the predetermined position.

[Function] According to the configuration of the present invention, a pulse current is supplied between the electrode and the workpiece which are disposed opposite to each other with a predetermined gap through a stationary electrolyte, and after this pulse current is turned off, the electrode is moved to the predetermined position. distance(
L) raise the electrode to enlarge the gap, spray fresh electrolyte into the enlarged gap to remove electrolysis products, etc. in the gap, and then lower the electrode a predetermined distance (L) to expand the gap. Since the position is reset, the workpiece can be finished machined while maintaining the machining gap constant over the entire machining surface of the workpiece (the machining gap increases as machining progresses).

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail and specifically with reference to the drawings.

1 to 4 show an embodiment of the present invention.

In FIG. 1.2, the electrolytic finishing device 1 includes an electrode 2
an electrode fixing device 3 that fixes the workpiece 4, a workpiece fixing device 5 that fixes the workpiece 4, a drive conversion section 7 that converts the rotational motion of the electrode drive section 6 into reciprocating motion, a power supply device 8 that generates a pulse current,
A control device 12 consisting of a motor drive control section 9, a processing condition control section 10, an electrolyte flow control section 11, etc., an input device 13 for inputting various data regarding the workpiece 4, an electrolyte filtration device 14 for filtering the electrolyte, and It consists of a processing tank 15, etc.

The electrode fixing device 3 has an electrode 2 made of, for example, pure copper or graphite attached to the lower end of a rod 16 provided at the bottom thereof, and a gap 17 such that the electrode surface 2a and the processed surface 4a of the workpiece 4 are spaced in a three-dimensional direction. Fix it to keep it. The electrode fixing device 3 includes an electrode drive section 6 and a drive conversion section 7.
Accordingly, the gap 17 is moved up and down to set it to a predetermined value. That is, the rotation of the motor 20 is controlled by control signals output from the motor drive control section 9 based on signals from the rotary encoder 18 and the tacho generator 19 of the electrode drive section 6, and the electrode fixing device 3 is moved up and down. A predetermined gap 17 is set between the electrode surface 2a and the processed surface 4a.

The work fixing device 5 is a highly insulating table made of granite or ceramics, and is fixed to the X table (not shown) of the X-Y table 21 of the electrolytic finishing device 1 together with the bottom plate of the processing tank 15 by bolts or the like. do. Further, the workpiece 4 is fixed to the upper surface of the workpiece fixing device 5 by bolts 22, etc., and thereby the workpiece 4, the workpiece fixing device 5, and the processing tank 15 are rotated by the movement knobs 23 and 24 of the X-Y table 21. When operated, it moves integrally in the X and Y directions.

A power supply device 8 that supplies a pulse current having a predetermined peak current density between the electrode 2 and the workpiece 4, and a machining condition control unit IO of the control device 12 that controls the power supply device 8, for example. It is configured as shown in Figure 3.

That is, the power supply device 8 includes a DC power supply unit 25 and a charging/discharging unit 26, and the DC power supply unit 25 includes a transformer 27 and a rectifier 28.
The voltage is lowered to a predetermined value by a transformer 27 and rectified by a rectifier 28 to obtain a direct current, which is supplied to capacitors 29-1 to 29-n, which will be described later.

The charging/discharging unit 26 also includes a plurality of capacitors 29-1 to 29-n that discharge charges between electrodes, and each of these capacitors 29-
Diodes 30-1 to 30-n are connected to diodes 1 to 29-n to prevent backflow of charges to the DC power supply section 25 side, and a discharge switch 31-1 is opened and closed to discharge charges to the y side.
31-n, and a charging switch 32 that supplies and disconnects power from the DC power supply section 25 to charge each of the capacitors 29-1 to 29-n to a predetermined value.

The machining condition control unit 10 that controls the charging/discharging unit 26 includes a voltage detector 33 that detects the charging voltage values of the capacitors 29-1 to 29-n, and a D/D ratio between the charging voltage values detected by the voltage detector 33 and A voltage comparator 35 that compares the first output from the A converter 34, and a charge detector that detects the completion and start of charging of the capacitors 29-1 to 29-n based on the output signal from the voltage comparator 35. 36, a current detector 37 that detects the current value of the charge discharged between the electrodes, and this current detector 37.
a peak hold circuit 38 that holds the peak value of the current value detected by the current comparator 40 that compares the peak current value held by the peak hold circuit 38 with the output value of the D/A converter 39; A gate that outputs an opening/closing drive signal to each of the discharge switches 31-1 to 31n based on an input signal from a pulse generator 41 that generates a pulse with a certain width and a current waveform setter 42 that sets the current waveform of the charge discharged between the poles. The circuit 43 and each of the capacitors 29-1 to 29-
Set the charging voltage value to be supplied to the D/A and send the signal to the D/A.
A charging voltage setting device 44 that outputs to the converter 34, a current setting device 45 that sets the current value flowing between the poles and outputs the signal to the D/A converter 39, and input data of the input device 13, etc. A CPU 46 that calculates and processes processing conditions etc. based on the
and a contact detector 47 that detects contact between the electrode 2 and the workpiece 4.
Consists of etc. Note that the reference numeral 48 in the figure indicates the discharge switch 31-
When 1 to 31-n are opened, each discharge switch 3 is
This is a diode that prevents 1-1 to 31-n from being destroyed.

Note that control of the CPO 46 when the capacitors 29-1 to 29-n are charged and discharged will be explained here. First, CP
U46 determines that the peak current density of the pulsed current to be supplied is based on the machining area S of the workpiece 4 that has been manually machined by the manual device 13 in advance, the on-time ton (hereinafter referred to as pulse width) of the pulsed current supplied between the electrodes, etc. A charging voltage value to be a predetermined value is calculated from a characteristic table input in advance to the storage device, and output to the charging voltage setter 44 of the processing condition control unit 10.Then, the capacitors 29-1 to 29-n are When the battery is charged at the charging voltage value, a charging completion signal is sent to the charging detector 36.
Input from Based on this signal, the CPU 46 outputs a control signal to the pulse generator 41 and current waveform setter 42 to turn on the gate circuit 43 and turn on the discharge switch 311.
31-n is turned on and a predetermined pulse current is supplied between the electrodes. Then, the current value of this pulse current is detected by the current detector 3.
7, and the peak value at that time is held by the peak hold circuit 38.

This held peak value is compared with a signal value obtained by converting the digital signal from the current setting device 45 into an analog signal by the D/A converter 39, and the result is sent to the CPU.
46. In this case, the comparison method of the current comparator 40 is to increase the count value of the counter (not shown) of the current setter 45 one step at a time from O, and the value obtained by D/A converting this value is the value of the peak hold circuit 38. When the peak current value is exceeded, the output of the current comparator 40 is inverted, and the count value of the counter at that time is stored in the CPU 46 as the peak current value.

Based on the stored peak current value, the CPU 46 corrects the set voltage value of the charging voltage setter 44 (for example, increases the set voltage value if the stored peak current value is lower than the temporarily set set current value, and adjusts the peak current value). If the value is larger than the set current value, the set voltage value is decreased), and the pulse current supplied between the electrodes is controlled so as to have a predetermined peak current density.

The input device 13 inputs various data and machining conditions regarding the workpiece 4 manually, and outputs these signals to the motor drive control section 9 and the machining condition control section 10 of the control device 12.

Further, the electrolyte filtration device 14 filters an electrolyte containing electrolytic products generated during processing, and the electrolyte flow control unit 1
Based on the control signal from 1, an electrolytic solution is supplied into the machining tank 15, and in order to eliminate electrolytic products generated between the electrode surface 2a and the machining surface 4a during machining, an electrolytic solution is supplied through the jet nozzle 49. to squirt fresh electrolyte into the gap.

Next, an example of the finishing operation by this electrolytic finishing apparatus 1 will be explained with reference to the flowchart of FIG. 4.

During finishing, the electrode 2 used for electrical discharge machining of the workpiece 4, or the remainder cut out by wire-cut electrical discharge machining, is fixed as the electrode 2 to the lower end of the rod 16 of the electrode fixing device 3, and the workpiece is Each workpiece 4 is attached to the fixing device 5 (50), and the input device 13 inputs the machining area S of the workpiece 4, the pulse width ton of the pulse current to be supplied, the pulse rest time t off, and the number of pulse currents supplied per knee n. , processing number No.
Parameters such as N2, machining gap δ, and electrode lifting distance are input (51). Then, the electrode 2 is lowered to bring the electrode surface 2a into contact with the processing surface 4a (52), and the contact detector 47 detects the position, which is set as the origin A.

Next, the electrolytic solution is supplied from the electrolytic solution filtration device 14 into the processing tank 15 (53) b, and the number of processing times is a predetermined number N.

Judgment whether or not (54) l,,,this judgment (54
) is No, the electrode 2 is raised from the origin A and set at a position where the machining gap δ is maintained (55), and the electrolyte is filled between the electrode surface 2a and the machining surface 4a,
When the electrolyte is stationary (meaning the state where the flow and movement of the electrolyte has almost stopped) (56), a control signal from the machining condition control unit 10 causes the power source 8 to be activated at a predetermined level according to the machining area S of the workpiece 4. pulse current, e.g. peak current density is 40A
/ crn2, a single pulse current with a pulse width ton of 20 m5ec is supplied between the poles (57). This pulsed current removes the oxide film and the like on the processed surface 4a of the workpiece 4, which is generated before the start of finishing processing or by supplying a pulsed current for improving surface roughness, which will be described later. When this pulse current is turned off, the motor 20 is driven by the signal from the motor drive control section 9 to raise the electrode 2 by a predetermined distance (L) inputted in advance (58), thereby separating the electrode surface 2a from the processing surface 4a. At the same time, fresh electrolytic solution is ejected from the ejection nozzle 49 into the enlarged gap to eliminate the oxide film etc. eluted into the gap (59).

After removing the oxide film, etc., the electrode 2 is lowered (60) by a distance (L), and the previous processing is repeated a predetermined number of times N.
1 or not is determined (61). If NO in this determination (61), the process returns to step (55) and the electrode 2 is reset to the initially set position. In this case, the machining gap between the electrode 2 and the workpiece 4 becomes larger than the initial machining gap δ as machining progresses.

If YES in step (61), that is, if machining has been performed a predetermined number of times N1, the pulse current supplied from the power supply device 8 is changed to a predetermined pulse current for improving surface roughness according to the machining area S. Switch (62). Then, set the electrode at the same position as in step (55) (63) l...
When the electrolyte in the gap becomes stationary (64), the pulsed current is supplied between the n-electrodes (65-66). This pulse current has, for example, a peak current density of 40 A/am'', a pulse width ton of 5 m5 ec, and a pulse rest time t off of 2.
A pulse current of 55 msec is continuously supplied 5 times.

When this pulse current is turned off, the steps (58) to
Similar to (60), raise electrode 2 by a predetermined distance (67)
At the same time, fresh electrolyte is ejected from the ejection nozzle 49 to eliminate electrolytic products in the gap (68) l, . . . The electrode 2 is lowered by a distance RL (69).

Then, it is determined whether the number of machining is N2 or not (70).If this determination (70) is No, the process returns to step (63), and if YES, the process returns to step (54). ) until YES becomes step (55)
- Repeat (70). When the answer is YES in step (54), all finishing operations are completed (71).

That is, in this embodiment, the oxide film etc. on the machined surface 4a of the workpiece 4 is removed in steps (55) to (61), and then the machined surface is improved while improving the surface roughness in steps (62) to (70). The process of finishing 4a into a mirror surface is repeated a predetermined number of times.

Note that if the result in step (54) is YES, without immediately ending the finishing process, for example, switch to a predetermined pulse current for forming a glossy surface that is different from the pulse current for improving the surface roughness, The finishing process can be completed by repeating steps similar to the steps (63) to (70), or the step (6) can be completed after step 54).
2) to (70) for improving the surface roughness may be performed, and then steps (55) to (61) for removing the oxide film may be performed to complete the finishing process.

As described above, in the finishing method by electrolytic machining according to the present invention, the electrode 2 is raised by a predetermined distance (L) after pulse current is supplied to enlarge the gap, and fresh electrolyte is poured into this gap. The electrode 2 is ejected to ensure that electrolytic products, etc. in the gap are removed, and then the electrode 2 is lowered by a predetermined distance (L) to always set the electrode 2 at the same position.
Although the machining gap between the workpiece 4 and the workpiece 4 increases as machining progresses, it can always be maintained constant over the entire machining surface 4a of the workpiece 4 when pulse current is supplied, and machining conditions can be made uniform. The transfer accuracy of the electrode 2 can be improved, and a mirror-like glossy surface can be obtained in a short time.

That is, according to the present invention, unlike the conventional electrolytic machining method in which the electrode 2 is machined while being fed, there is a machining gap in the feeding direction (Z-axis direction) of the electrode 2, and a machining gap in a direction different from this direction, for example, in the X and Y directions. The machining gap is different (the electrode 2 is fed only in one direction, and the feeding direction is always maintained at a constant machining gap, but in the direction perpendicular to the feeding direction, the machining gap gradually increases as machining progresses). Experiments have confirmed that this uniformity of the machining gap is particularly effective in electrolytic finishing, which is performed by supplying a pulsed current between the poles in a static liquid.

[Effects of the Invention] Since the present invention is configured as described above, it produces the following effects.

- The machining gap between the electrode and the workpiece can be maintained constant over the entire machining surface, making the machining conditions uniform and achieving high-precision surface quality such as a mirror-like glossy surface in a short time.

■A complicated servo mechanism for electrode feeding is no longer required, reducing the cost of processing equipment.

[Brief Description of the Drawings] Figure 1 is a front view of the electrolytic finishing apparatus of the present invention, Figure 2 is a front view of the electrolytic finishing apparatus of the present invention;
The figure is a block diagram of the device, Figure 3 is a block diagram of the main parts,
FIG. 4 is a flowchart showing an example of the finishing operation. 1... Electrolytic finishing processing device, 2... Electrode, 4...
Work, 8... Power supply device, 12... Control device, 14
...Electrolyte filtration device, 46...CPU, Patent applicant: Shizuoka Seisaku6ki Co., Ltd. Representative Shigeo Suzuki Figure 1

Claims (1)

[Claims] (1) In finishing processing of a workpiece by supplying a pulsed current between the poles of the electrode and the workpiece, which are placed opposite each other in a static electrolyte, a. B. Raise the electrode a predetermined distance (L) after supplying the pulse current to enlarge the gap between the electrode and the workpiece; C. Spray the electrolyte into the enlarged gap to close the gap. A finishing method by electrolytic machining, comprising the steps of: removing electrolytic products, etc.; and (d) lowering the electrode by a predetermined distance (L) and resetting it at the predetermined position.