FORM2
THE PATENTS ACT,1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention: AUTO SEQUENCING OF ELECTRODES ON FO550S SPARK EDM MACHINE FOR MULTIPLE PARTS MACHINING
2. Applicant(s):

(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company.
(c)ADDRESS: L & T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

TECHNICAL FIELD OF THE INVENTION
This invention relates generally to a machining device and a method for performing machining operation. More particularly the present invention relates to improved spark electrical discharge machine for multiple parts machining and a method thereof. It provides for auto sequencing of electrodes on spark EDM machine for multiple parts machining and a method thereof.
BACKGROUND AND THE PRIOR ART
The present invention relates to auto sequencing of electrodes on FO550S spark EDM machine for multiple parts machining. It is used to cut blind profiles in metallic blocks for various industrial applications, particularly in Die & Mould making. The spark EDM machining (Electrical Discharge Machining) process uses an electrically charged electrode that is configured to a specific geometry. It is used to burn the geometry of the electrode into a metal component. This process creates female replica of electrode geometry indie or mould part. The spark EDM process is commonly used in the production of dies and molds.
Two metal parts submerged in an insulating liquid are connected to a source of current which is switched on and off automatically depending on the parameters set on the controller. When the current is switched on, an electric potential is created between the two metal parts. If the two parts are brought together to within a fraction of a milimeter, the electrical potential is discharged and a spark jumps across. Where it strikes, the metal is heated up so much that it melts. Innumerable such sparks spray, one after the other (never simultaneously) and gradually shape the desired form in the piece of metal, according to the shape of the electrode. Several hundred thousand sparks must fly per second to erode metal from work piece.
The spark EDM is used in tool room for machining of core & cavity of moulds & dies. Normally, multiple jobs are machined in single setting. It implies that on single machine table, multiple jobs are loaded & machined so that after completion of one job, machining of another job gets started automatically. The synchronization of electrodes from one job to another job is required to finish the job. Enabling this through programming helps to run the

machine in unattended mode. This leads to increase in the total equipment effective performance. As the Spark EDM machine controller does not have an interactive facility to develop the logic for sequencing of electrodes from one job to another job, utilization of machine is affected due to interruptions required to change from one job to another. Hence it became essential to develop a CNC program to sequence a variety of jobs with variety of electrodes.
GB15446S0 provides the control arrangement that serves to control an electrical discharge machine tool on the basis of commands delivered by a punched-tape reader via a decoder. The machine tool has a work table which can be moved in two coordinate directions X and Y. The tool can be moved in the third direction Z perpendicular to the two said directions. A device for differentiating the control commands is attached to the output of the decoder, this device being connected firstly via a device for ending the movements of the work table to a control block and secondly to a control device for the reader. A further input of the device for ending the table movement is connected via a monitoring device for the position of the tool electrode in the direction of the Z-coordinate to a comparator for the position of the tool electrode. The monitoring device for the position in the direction of the Z-coordinate is attached via an electronic amplifier to a feed regulator for the tool electrode. A further output of the device for ending the table movement is attached to the control device for the reader. A control arrangement of this type enables the entire working sequence of the electrical discharge machine tool to be automated.
US4504722 provides an electric discharge machining apparatus capable of automatically optimizing the machining stabilizing condition including set voltage of machining pulse, duty factor of the pulse, electrode raising period and working fluid pressure, and hence capable of being full-automated. Each machining stabilizing condition is successively changed within a predetermined range and set when the maximum effective discharge generation rate is obtained. Spark machining is affected on the basis of the set value.
To overcome the disadvantages associated with above prior arts, the present invention provides an improved spark electrical discharge machine for multiple parts machining.

OBJECTS OF THE INVENTION
A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.
Another object of the present invention is to provide an improved spark electrical discharge machine for multiple parts machining.
Another object of the present invention is to provide method for multiple parts machining using an improved spark electrical discharge machine.
Another object of the present invention is to provide auto sequencing of electrodes on spark EDM machine for multiple parts machining.
These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
There is provided auto sequencing of electrodes on spark EDM machine for multiple parts machining and a method thereof.
Other aspect improved spark electrical discharge machine for multiple parts machining, said machine comprising a controller; a dielectric means for substantially lowering temperature in machining area thereby causing dionization thus removing residual metal particles and enabling creation of a spark; a plurality of electrodes configured to a predetermined geometry; a spark generator for producing spark; a numerical control means for automation operated by a preprogrammed commands encoded on a storage medium; wherein said a numerical control means configured to provide for electrode sequencing machining of a plurality of jobs with multiple electrodes.
Other aspect of the present invention provides method for multiple part machining using an improved spark electrical discharge machine, said method comprising the steps of directing

an electrode towards a workpiece; allowing concentration of electric field at substantially narrowest gap between said electrode and workpiece; creation of an ionised channel between said electrode and said workpiece; triggering of a spark whereby the workpiece material melt locally; cutting off the current supply thereby facilitating implosion of spark; evacuation of metal particles by flushing with dielectric means; wherein a numerical control means for automation operated by a preprogrammed commands encoded on a storage medium and provide for electrode sequencing machining of a plurality of jobs with multiple electrodes.
Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.
Fig 1 illustrates the screen shots of different stages during machining operation.
Fig 2 illustrates other stage during machining operation.
Fig 3 illustrates other stage during machining operation.
Fig 4 illustrates other stage during machining operation.
Fig 5 illustrates other stage during machining operation.
Fig 6 illustrates yet other stage during machining operation.
Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of

some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.
DETAILED DESCRIPTION OF THE INVENTION
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.
By the term "substantially" it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

Accordingly in the present invention Auto sequencing of electrodes on FO550S spark EDM machine for multiple parts machining is provided. It is used to cut blind profiles in metallic blocks for various industrial applications, particularly in Die & Mould making.
Spark EDM Operation:-
The spark EDM machining (Electrical Discharge Machining) process uses an electrically charged electrode that is configured to a specific geometry. It is used to burn the geometry of the electrode into a metal component. This process creates female replica of electrode geometry in die or mould part. The spark EDM process is commonly used in the production of dies and molds.
WORKING:
Two metal parts submerged in an insulating liquid are connected to a source of current which is switched on and off automatically depending on the parameters set on the controller. When the current is switched on, an electric potential is created between the two metal parts. If the two parts are brought together within a fraction of a milimeter, the electrical potential is discharged and a spark jumps across. Where it strikes, the metal is heated up so much that it melts. Innumerable such sparks spray, one after the other (never simultaneously) and gradually shape the desired form in the piece of metal, according to the shape of the electrode. Several hundred thousand sparks must fly per second to erode metal from work piece.
Spark EDM machine:-
In a Spark EDM, the required shape is formed negatively in the metal with a three-dimensional electrode. Co-ordinated movements of electrode in the main axes x, y, c, z, cavities of varied shapes can be created in metal part, which can not be achieved by any other machining system.
For example, a helicoid cavity or a rectangular hole in one single steel block or the machining of an extremely thin, hardened steel sheet without subjecting the same to any mechanical pressure.
Spark EDM machine is a special purpose machine used in Tool room industry. Copper, graphite, copper tungsten, steel material are used as electrode for making blind cavities in

metallic blocks. The job acts as Cathode & EDM wire acts as Anode having high voltage difference. The energy is transferred to the job in the form of spark that melts away the work piece causing profile cutting action.
Construction:-
The Machine works on the principle of Electro discharge machining, where wire acts as a electrode used to produce the cutting action in the solid work piece. As stated earlier, the electrode maintains a gap called as spark gap between job and the wire. A spark generated between the gap causing metal to erode in following stages-Principle of EDM Machining
The dielectric (water or mineral oil) has the purpose of lowering the temperature in the machining area, causing deionization, removing the residual metal particles and of enabling creation of the spark.
Electro discharge machining:-
The electrode & work piece is separated from each other & the gap is filled with dielectric medium. The gap is called as spark gap. The electrodes are smaller than the required cavity size by an amount equal to spark gap. The sparks, produced by a spark generator, will create a succession of craters in the work piece at regular intervals. Each spark develops a temperature of between 8000and 12000 °C. The size of the crater depends on the energy, governed by the spark generator. The range of the spark gap varies between a few microns and 1 mm.
The EDM process is made up of six stages:
Procedures for EDM:
The JOB stage - Indicate the number of workpiece(s), of cavity(ies), of electrode(s) and of
machining pass(es) needed for the JOB as a whole.
The TOOLS stage - Indicate the size of the electrodes and their positions in the tool-changer. Measure the offsets and their positions in the tool-changer.

The WORKPIECE stage - Define the origins and the positions of the work pieces in the magazine
The CAVITY stage - Establish the point of departure and the direction of machining
The EDM stage - Indicate all the information needed for machining.
The ISO stage - View the machining programme, simulate it and run it.
Purpose of invention:
The spark EDM is used in tool room for machining of core & cavity of moulds & dies. Normally, multiple jobs are machined in single setting. It implies that on single machine table, multiple jobs are loaded & machined so that after completion of one job, machining of another job gets started automatically. The synchronization of electrodes from one job to another job is required to finish the job. Enabling this through programming helps to run the machine in unattended mode. This leads to increase in the total equipment effective performance. As the Spark EDM machine controller does not have an interactive facility to develop the logic for sequencing of electrodes from one job to another job, utilization of machine is affected due to interruptions required to change from one job to another. Hence it became essential to develop a CNC programme to sequence a variety of jobs with variety of electrodes.
Implementation Phase:
Before stage: -
In work piece stage, electrode magazine position value provided by machine technology was
default "0".
After stage:-
The value in the preparation stage for the magazine position changed to "1". These results in
sequencing of multiple electrodes available in the electrode magazine to spark erode multiple
jobs one after another without manual interventions.

By changing the value from 0 to 1, the machine controller understands that multiple work offsets (e.g. G54, G55, G56, G57...) value is to be considered for machining. The tool stage (electrode stage) recognizes that multiple electrodes will spark erode multiple corresponding
jobs (having work offsets G54,G55,G56,G57 ).
After this, the ISO stage generates the machining programs & run it.
ADVANTAGES:
1. Electrode sequencing is possible to machine multiple jobs with multiple electrodes& run it in unmanned mode for long durations.
2. It increases the utilization of the machine by 35%.
The novel feature of the invention is that there is no documentation of customization done by inventor in Machine manufacturer's manual. The graphic user interface of the machine also does not have any HELP section where the said details are available. It is purely a result of innovative experiments done by the inventor.
Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein with modifications. However, all such modifications are deemed to be within the scope of the claims.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

WE CLAIM:
1. An improved spark electrical discharge machine for multiple parts machining, said
machine comprising:
a controller;
a dielectric means for substantially lowering temperature in machining area thereby causing dionization thus removing residual metal particles and enabling creation of a spark;
a plurality of electrodes configured to a predetermined geometry;
a spark generator for producing spark;
a numerical control means for automation operated by a preprogrammed commands encoded on a storage medium;
wherein said a numerical control means configured to provide for electrode sequencing machining of a plurality of jobs with multiple electrodes.
2. Machine as claimed in claim 1 wherein said electrode is made substantially of copper, graphite, tungsten, steel and the like for making blind cavities in metallic blocks.
3. Machine as claimed in claim 1 wherein said dielectric means placed between a spark gap formed between said electrode and said workpiece.
4. Machine as claimed in claim 1 wherein said spark having temperature approximately between 8000 and 12000 °C.
5. A method for multiple part machining using an improved spark electrical discharge machine, said method comprising the steps of:

directing an electrode towards a workpiece;
allowing concentration of electric field at substantially narrowest gap between said electrode and workpiece;
creation of an ionised channel between said electrode and said workpiece;
triggering of a spark whereby the workpiece material melt locally;
cutting off the current supply thereby facilitating implosion of spark;
evacuation of metal particles by flushing with dielectric means;
wherein a numerical control means for automation operated by a preprogrammed commands encoded on a storage medium and provide for electrode sequencing machining of a plurality of jobs with multiple electrodes.
6. An improved spark electrical discharge machine for multiple parts machining as herein described and illustrated with reference to accompanying drawings.
7. A method for multiple part machining using an improved spark electrical discharge machine as herein described and illustrated with reference to accompanying drawings.