JPS6119511A - Method and apparatus for electric discharge machining - Google Patents

Abstract

PURPOSE:To attain high accuracy electric discharge machining without leaving any unworked portions by providing a discharge level detector and narrowing a gap between an electrode and a workpiece in the start of working for forcible discharge which is thereafter changed over to normal electrospark machining. CONSTITUTION:In an electric discharge machining apparatus which interposes working liquid between an electrode 1 and a workpiece 2 to apply pulse voltage from a power source 3 is installed a discharge level detector 7, and the electrode 1 is forcibly moved close to the work 2 by a feed control unit 4 and a drive unit 5 in the beginning of working and the reworking. When discharge takes place and discharge current reaches a predetermined value, said detector 7 is operated, and the feed control unit 4 changes over the control signal to a discharge condition detector 6 to continue thereafter normal electric discharge machining and complete the working. Thus, high accuracy electric discharge machining is attained without leaving any unworked portions of the work.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electric discharge machining method of an electric discharge machining apparatus and an improvement of the apparatus.

[Prior art]

Figure 2 shows a conventional device, in which (1) is the electrode, (2)
) is the workpiece, (3) is the power source that generates a pulsed voltage,
(5) is a drive device for moving the electrode (1), and (4) is a force sending control device for controlling the drive device (5). Further, (6) is a discharge state detector, which operates the feed control device (4) according to the discharge state, and detects the electrode (1) and the workpiece (2).
) to keep the distance constant.

Next, to explain the operation, the workpiece (2) is
By applying a pulsed voltage from 3), electric discharge occurs between the electrode (1) and machining is performed. Feed control device (4
) is connected to the electrode (1) by the signal from the discharge state detector (6).
) and the workpiece (2), the drive device (5) is operated to perform machining, and when the electrode (1) reaches the set position, it automatically stops and machining begins. Complete.

However, in electrical discharge machining, in order to confirm the machining dimensions, machining is often interrupted and measurements are taken. Generally, during electrical discharge machining, the machining fluid interposed between the electrode (1) and the workpiece (2) contains machining powder (8) and carbon due to thermal decomposition of the machining fluid, as shown in Figure 6. etc. (8) are suspended and balanced at a constant concentration, keeping the distance between the electrode (1) and the workpiece (2) constant. This is done by widening the distance from the material (2) and removing machining fluid, machining powder, carbon, etc. (8). Therefore, if there is an interruption in measurement during machining, the machining fluid will be updated during reprocessing, so processing powder, carbon, etc. suspended in the machining fluid (8.
) decreases, the electrical resistance of the machining fluid increases, and when remachining, the distance between the electrode (1) and the workpiece (2) must be made smaller than before the interruption in order for electrical discharge to occur. .

For this reason, in conventional devices, when reprocessing is performed after an interruption such as a measurement, the electrode (1) approaches the workpiece (2) at a sufficient distance to generate an electric discharge. ) has the disadvantage that it automatically stops when it reaches a preset machining completion position, and does not carry out additional machining for the remaining tens of microns, or does not process even if machining is restarted.

[Summary of the invention]

This invention was made for the purpose of eliminating such drawbacks of conventional electrical discharge machining equipment.A discharge level detector is installed in the conventional electrical discharge machining equipment, and the electrode is forcibly brought close to the workpiece when starting machining or remachining. A certain amount of electrical discharge is generated without fail, and the electrical discharge machining is continued until the normal electrical discharge knee switching setting position is reached by waiting for the signal from the electrical discharge level detector that detects the electrical discharge flow, etc. Therefore, it is an object of the present invention to provide an electric discharge machining method and apparatus that realize high-precision electric discharge machining.

[Embodiments of the invention]

FIG. 1 is a block diagram showing one embodiment of the present invention, and (1) to (6) are completely the same as the conventional device described above. (7) is a discharge level detector which generates a signal when, for example, the discharge current, average voltage, or number of discharges reaches a certain value. (4) is a feed control device that forcibly brings the electrode (1) close to the workpiece (2) until a signal is received from the discharge level detector (7) at the start of machining;
When the signal from the discharge level detector (7) is received, it switches to the discharge state detector (6) and sends the electrode (1) to the set position.

Next, the operation will be explained. At the time of starting machining or re-machining, the electrode (1) is applied with a pulsed voltage from the power source (3), and the feed control device (4) and drive device (5) apply electrical discharge to the workpiece (2). They are forced to approach the area until they see it occur. If no discharge occurs at this time, the electrode (
1) approaches the workpiece (2). Then, when the distance between the electrode (1) and the workpiece (2) becomes smaller and a discharge occurs, and the discharge current reaches a certain level, the discharge level detector (7)
operates and generates a signal. Upon receiving this signal, the feed control device (4) immediately transmits the control signal to the discharge state detector (6).
) to return machining to normal. After that, continue processing 1.
When the electrode (1) reaches the set position for automatic stop, the electrode (1)
stops and machining is completed.

In the above embodiment, a method was described in which the electrode (1) was forcibly brought close to the workpiece (2) until the signal was received from the discharge level detector (7), that is, until the discharge started. If the electrode (1) does not discharge even if it exceeds the set position for automatic stop, move the electrode (1) to the set position by a certain amount set according to the machining conditions (discharge current, pulse width, pause time, etc.). [Effect of the Invention] As described above, according to the present invention, at the start of machining, there is no gap between the electrode and the workpiece. After the electrical discharge is forcibly generated and the electrically conductive materials such as machining powder in the machining fluid interposed between the electrode and the workpiece reach an equilibrium state, the mode is switched to normal discharge and machining is continued, and the electrode is Since the machine is designed to stop and complete machining when it reaches the set automatic stop position, there is no leftover machining, and highly accurate electrical discharge machining is now possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing a conventional electrical discharge machining apparatus, and FIG. 6 is a sectional view showing a discharge state. (1) is the electrode, (2) is the workpiece, (3) is the power source, (4
) is a feed control device, (5) is a drive device, (6) is a discharge state detector, (7) is a discharge level detector, (8 is a processing powder, carbon, etc.). Note that the same symbols in each figure are They indicate the same or equivalent parts. Agent Patent Attorney Sanro Kimura Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) In electrical discharge machining equipment that processes the workpiece by interposing machining fluid between the electrode and the workpiece and applying a pulsed voltage, the distance between the electrode and the workpiece at the start of machining A method of electric discharge machining characterized by forcibly generating electric discharge by bringing the two close together, and then switching to normal electric discharge machining. (2) If no discharge occurs even when the electrode is at the set position, move the electrode a certain distance set according to machining conditions such as discharge current, pulse width, or rest time to encourage discharge, and then 2. The electric discharge machining method according to claim 1, wherein the electric discharge machining method is switched to normal electric discharge machining at the point where the electric discharge machining is performed. (3) In an electrical discharge machining device that processes the workpiece by interposing a machining fluid between the electrode and the workpiece and applying a pulsed voltage, the electrode and the power source that generates the pulsed voltage are used. a drive device for moving the electrode; a feed control device for controlling the drive device; a discharge state detector that detects a discharge state during electrical discharge machining and sends a signal to the feed control device; and at the start of machining. A voltage application and electrode movement control device comprising: a discharge level detection device that detects a discharge current during forced discharge and sends a signal to the feed control device.