Electro-discharge machining apparatus
AssigneeSpark Tec Limited
InventorMohamed F. El-Menshawy
Life of this patent
Estimating the term…
Abstract
An electro-discharge machining apparatus includes an electrode carrier on which there are mounted a plurality of separate electrodes. A circuit for each electrode applies a high voltage discharge initiating pulse followed by an extended lower voltage discharge sustaining pulse to the associated electrode. A gap voltage sampling circuit samples the voltage between the electrode and the workpiece and a "low wins" circuit passes a signal representing the lowest gap voltage as a feedback signal for a servo-actuator which moves the electrode holder towards and away from the workpiece.
Claims16
An electro-discharge machining control comprising first and second current sources of relatively high and low voltage respectively, first switch means for repeatedly connecting said second source to an output for a first duration for connection to an electrode and second switch means for repeatedly connecting said first source to said output only when said second source is connected to said output and for a constant duration which is shorter than the first duration of the connection of said second source to the output.
An electro-discharge machining apparatus for texture machining the surface of a metal roll comprising:
- roll support means for rotatably supporting a roll for machining;
- a support structure movable in a direction parallel to the roll axis;
- an electrode holder mounted on said support structure and movable relative thereto in a direction transverse to the roll axis;
- a plurality of separate electrodes mounted on said electrode holder and electrically insulated from one another;
- a plurality of first switch means for connecting said electrodes to a source of relatively high voltage;
- a plurality of second switch means for connecting said electrodes to a source of relatively low voltage;
- initiation pulse control means for repeatedly supplying relatively short constant duration initiation pulses to said first plurality of switch means so as to apply relatively short duration relatively high voltage pulses to said electrodes;
- voltage detection means for detecting the voltage across gaps between the electrodes and the roll;
- machining pulse control means for repeatedly supplying relatively long duration machining pulses to said second plurality of switch means so as to apply relatively long duration relatively low voltage pulses to said electrodes;
- machining pulse inhibiting means, responsive to said voltage detecting means, for interrupting the supply of machining pulses to said second plurality of switch means in the event that said voltage detecting means detects a short circuit between an electrode and the roll;
- and
- actuator means, responsive to said voltage detecting means, for displacing said electrode holder towards and away from the roll surface in accordance with detected discharge conditions.
Electro-discharge surface texture machining apparatus for providing a predetermined texture on a surface of a workpiece, comprising:
- at least one electrode holder;
- at least one electrode mounted on said electrode holder;
- a base structure;
- a workpiece support;
- means mounting said electrode holder and said workpiece support on said base structure for scanning movement of said electrode over a surface of a workpiece to be texture machined;
- current pulse supply means for supplying pulses of machining current to said electrode, said current pulse supply means comprising:
- (a) a source of relatively low voltage machining pulses of predetermined frequency and of predetermined duration;
- (b) adjustment means for adjusting the frequency and duration of said machining pulses;
- and
- (c) a source of relatively high voltage initiation pulses of a fixed duration, where said fixed duration is short relative to the machining pulse duration, said initiation pulses coinciding with the commencement of each of said machining pulses;
- and
- means sensitive to discharge conditions for adjusting the proximity of the electrode to the surface.
An electro-discharge surface texture machining apparatus for providing a predetermined texture on a surface of a workpiece, comprising:
- a base structure;
- means supporting a workpiece on said base structure;
- a carriage mounted on said base structure;
- a plurality of electrode holders mounted on said carriage;
- a plurality of electrodes mounted on said electrode holders;
- transport means for said carriage and said workpiece support means for systematically scanning each of said electrodes over the whole surface of a workpiece to be texture machined;
- a plurality of feed means for independently moving respective electrode holders relative to the carriage towards and away from the workpiece surface along spaced paths transverse to the scanning motion of the electrodes relative to the workpiece;
- and
- means for supplying discharge current pulses to each of said electrodes;
- each of said feed means comprising an independent servo-drive including:
- a sensing device for sensing a discharge condition at the corresponding electrode;
- and
- a closed loop control means for moving the associated electrode holder in response to said sensing device.
Dependencies are inferred from the claim text.