DESC:FIELD OF THE INVENTION
[0001] The current invention generally relates to a multi-head tool electrode assembly, and in particular to machining systems including the multi-head tool electrode assembly and method of operation for precise machining in microscale.

BACKGROUND
[0002] Electrochemical discharge machining (ECDM) and electrical discharge machining (EDM) are non-traditional machining processes that can be used for fabricating or machining micro-scale features such as micro-holes, micro-channels and 3-dimensional (3D) patterns on various materials. Since the material removal process in EDM or ECDM does not involve sophisticated technologies, such as laser beam or electron beam, it is more economical. As the name implies, electrochemical discharge machining involves electrolysis in combination with electrical discharge for the machining process. A typical electrochemical discharge machine (ECDM) includes an electrolytic cell including a small electrode (tool electrode) and a much larger counter-electrode (anode) in an electrolyte. On applying a pulsating voltage across the electrodes, a gas film forms at the smaller electrode upon electrolysis. When the pulsating voltage applied is above a critical value an electrochemical discharge occurs through the gas film formed at the smaller electrode through the electrolyte. The electrochemical discharge releases high thermal energy for material removal from a workpiece. EDM can machine a workpiece submerged in a dielectric fluid by using a series of electrical discharges (sparks) between a tool electrode and the workpiece, which acts as the anode. The electrical discharge results in localized melting and vaporization of the material, which is flushed away by the dielectric fluid. From the materials perspective, ECDM is versatile as electrically conducting and non-conducting materials can be machined.
[0003] The machining using ECDM and EDM can be quite time-consuming as the machining is performed using the small, tool electrode. When using a standard 0.010” O brass wire as the tool electrode, the cutting speed can be in a range of 18 to 20 inches per hour. A faster cutting speed may require a tool electrode that is much more rigid and stiffer when compared to a tool that may be used at a lower cutting speed. A faster cutting speed is at the cost of higher wear and tear, which may even result in shutdowns.
[0004] Limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of described systems with some aspects of the present disclosure, as set forth in the remainder of the present application and with reference to the drawings.
SUMMARY
[0005] According to embodiments of the present disclosure, a multi-head tool electrode assembly is provided. The multi-head tool electrode assembly comprises an array including a plurality of stators and a plurality of rotors provided on a mount. The plurality of rotors in the array is positioned relative to the plurality of stators to enable rotation of the plurality of rotors on application of voltage to the plurality of stators. The multi-head tool electrode assembly further comprises at least one tool electrode mechanically coupled to the plurality of rotors to enable rotation of the at least one tool electrode.
[0006] In another embodiment of the present disclosure, an electrochemical discharge machining (ECDM) system is provided. The electrochemical discharge machining system includes a multi-head tool electrode assembly. The multi-head tool electrode assembly comprises an array comprising a plurality of stators and a plurality of rotors provided on a mount. The plurality of rotors in the array is positioned relative to the plurality of stators to enable rotation of the plurality of rotors on application of voltage to the plurality of stators. The multi-head tool electrode assembly further comprises at least one tool electrode mechanically coupled to the plurality of rotors to enable rotation of the at least one tool electrode. The electrochemical discharge machining system further comprises an electrolytic bath comprising an electrolyte. The electrochemical discharge machining system further comprises an anode in contact with the electrolyte. A workpiece to be machined is provided in the electrolytic bath and placed between the anode and the at least one tool electrode. The electrochemical discharge machining system further comprises a power source to provide voltage across the anode and the least one tool electrode to provide an electrical discharge for machining the workpiece.

[0007] In yet another embodiment of the present disclosure, an electrical discharge machining system is provided. The electrical discharge machining (EDM) system includes a multi-head tool electrode assembly. The multi-head tool electrode assembly comprises an array comprising a plurality of stators and a plurality of rotors provided on a mount. The plurality of rotors in the array is positioned relative to the plurality of stators to enable rotation of the plurality of rotors on application of voltage to the plurality of stators. The multi-head tool electrode assembly further comprises at least one tool electrode mechanically coupled to the plurality of rotors to enable rotation of the at least one tool electrode. The electrical discharge machining system further comprises a conducting workpiece to be machined in a dielectric bath proximate to the at least one tool electrode. The electrical discharge machining system further comprises a power source to provide voltage across the conducting workpiece and the least one tool electrode to provide an electrical discharge for machining the conducting workpiece.

BRIEF DESCRIPTION OF DRAWINGS
[0008] The advantages of embodiments of the disclosure may be more readily ascertained from the description of certain examples of the embodiments of the disclosure when read in conjunction with the accompanying drawing, in which:
[0009] FIG. 1 is a schematic diagram of a multi-head tool electrode assembly, in accordance with embodiments of the present disclosure;
[0010] FIG. 2 is a schematic diagram of an exemplary electrochemical discharge machining system including a multi-head tool electrode assembly, according to embodiments of the present disclosure; and
[0011] FIG. 3 is a schematic diagram of an exemplary electrical discharge machining system including a multi-head tool electrode assembly, in another embodiment of the present disclosure.
[0012] Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description of exemplary embodiments is intended for illustration purposes only and is, therefore, not intended to necessarily limit the scope of the present disclosure.

DETAILED DESCRIPTION
[0013] The following description and example illustrate some exemplary embodiments of the disclosed invention in detail. Those of skill in the art will recognize that there are numerous variations and modifications of this invention that are encompassed by its scope. Accordingly, the description of a certain exemplary embodiment should not be deemed to limit the scope of the present invention.
[0014] The term “comprising” as used herein is synonymous with “including,” or “containing,” and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.
[0015] All numbers expressing quantities of ingredients, property measurements, and so forth used in the specification are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth herein are approximations that may vary depending upon the desired properties sought to be obtained.
[0016] As used herein, the terms “machining”, “tooling”, and “patterning” are interchangeably used, and refer to the process of designing, cutting, drilling, shaping, and forming materials to produce parts that may be utilized for manufacturing and/or in an industry.
[0017] Machining systems such as electrical discharge machines (EDMs) and electrochemical discharge machines (ECDMs) are used for machining hard and/or complex materials. While EDMs are commonly used to machine electrically conducting materials through controlled electrical discharges between a tool electrode and a workpiece, ECDMs expand the scope to include electrically conducting and non-conducting materials by combining electrochemical and electrical discharge processes. In EDMs and ECDMs, maintaining a controlled gap between the tool electrode and the workpiece is critical for achieving precise material removal or machining.
[0018] Machining using ECDMs and/or EDMs can be quite time-consuming as it is performed using a small, tool electrode. Embodiments of the present disclosure provide a multi-head tool electrode assembly including more than one (multiple) tool electrode that can simultaneously pattern on a workpiece. Advantageously, multiple electrodes in parallel enable faster material removal compared to a machining system including a single-electrode. In a multi-head tool electrode, discharge activity is distributed across multiple electrodes as a result an overall machining efficiency is significantly enhanced, thus reducing cycle times. The multi-electrode tooling is particularly beneficial when machining large surfaces or creating intricate patterns over a wide area on a workpiece as the multiple electrodes can operate simultaneously over different parts of the workpiece, ensuring uniform material removal and reducing the number of tool passes required. Further, by distributing the machining workload across multiple electrodes, the risk of localized overheating and workpiece deformation is minimized, leading to improved surface quality. Additionally, the wear on individual electrodes is reduced, resulting in more consistent performance over extended periods. Another advantage of the present disclosure is the flexibility associated with multiple electrodes, upon breakdown of a single electrode machining operation may be continued with the remaining electrodes, thus minimizing downtime.
[0019] A significant feature of the present disclosure is the rotation of each of the multiple electrodes. It is known that rotating an electrode during machining distributes the wear uniformly across the electrode surfaces thus extending the lifespan of the electrode. During machining, debris generated by material erosion can accumulate in the gap, leading to unstable machining conditions or poor surface finishes. The rotation of the electrode facilitates more efficient removal of debris from the gap, as centrifugal forces assist in flushing eroded particles away from the machining area, maintaining a clean and stable discharge zone. Rotating the electrode helps create more uniform discharge patterns, which can lead to smoother surfaces on the machined workpiece. This is particularly important in precision applications where surface finish is critical. Rotating electrodes can enhance the cooling effect by promoting better circulation of the dielectric fluid or electrolyte around the tool electrode and workpiece. This reduces localized heating, improving both tool and workpiece longevity. Thus, the rotation of the multiple electrodes ensures consistent performance and accuracy throughout the machining cycle.
[0020] FIG. 1 is a schematic diagram of a multi-head tool electrode assembly 100, according to embodiments of the present disclosure. The multi-head tool electrode assembly 100 may be incorporated into a machining system for patterning a workpiece(s). The multi-head tool electrode assembly 100 comprises an array 102 provided on a mount 104. The array 102 comprises a plurality of stators 106 and a plurality of rotors 108.
[0021] The mount 104 is retractable. In one embodiment, the mount 104 forms part of a computer numerical controller (CNC) machine capable of translational motion along the three directions in an X-Y-Z axes plane. In some embodiments, the mount 104 performs translational motion along z-axis (retractable motion) in the X-Y-Z axes plane. The translational or retractable motion of the mount 104 may result in a motion of the plurality of stators 106, and plurality of rotors 108, as a whole. In some embodiments, the motion of each of the plurality of stators 106 or plurality or rotors 108 may be controlled independently, in addition to an overall movement along with the mount 104.
[0022] At least one tool electrode 110 is mechanically coupled to the plurality of rotors 108 that enables rotation of the at least one tool electrode 110. The term “at least one”, as used herein refers to including one, or more than one tool electrode. In one embodiment, the at least one tool electrode 110 is mounted on a miniature bearing and coupled to the rotor of the plurality of rotors 108 for efficient rotation.
[0023] The plurality of rotors 108 includes more than one rotor and the plurality of stators 106 includes more than one stator, as shown in FIG. 1. In one embodiment, a number of stators in the plurality of stators 106 is in a range of 5 to 9000. In some embodiments, a number of rotors in the plurality of rotors 108 is in a range of 2 to 3000.
[0024] A rotor of the plurality of rotors 108 comprises a permanent magnet that is operable to carry out rotational motion under the influence of a changing magnetic field. In one embodiment, the rotor of the plurality of rotors 108 is composed of tungsten carbide, ferritic stainless steel, or similar materials. In some embodiments, the plurality of rotors 108 is cylindrical in shape having a diameter in a range of 0.5 millimeters (mm) to 3.175 mm. It is preferred that the magnetic field is applied radially (in a direction along a radius or the diameter) to the plurality of rotors 108 as opposed to the application of a magnetic field in an axial direction (in a direction along an axis of rotation). The radial magnetic field on the plurality of rotors 108 is accomplished by placing the plurality of stators 106 around the plurality of rotors 108 in the array 102. The rotation of the plurality of rotors 108 is supported by mounting the plurality of rotors 108 on a mount bearing on the mount 104, however, similar mounts as known in the prior art may be utilized.
[0025] The stator of the plurality of stators 106 is stationary and includes a rod on which metal coils are wound around to form windings. Suitable metals of the metal coil include copper and other electrically conducting metals. In one embodiment, a number of windings on the rod is in a range of 4 to 6. The rod of the plurality of stators 106 may be made of a permanent magnet, or a material that may behave like a magnet in presence of an oscillating electric field. When the windings are connected to an electric current source (not shown) it functions as an electromagnet, or in other words it generates a magnetic field to form a magnetized stator. A strength of the magnetic field generated may be controlled by changing parameters such as the number of windings on each of the plurality of stators 106, the material constituting the stator, dimensions of the stator, and an applied voltage. The stator, in one embodiment, is made of a ferrite rod of diameter in a range of 0.5 millimeters (mm) to 1 mm with windings in a pre-determined phase configuration. The term, “ phase configuration” indicates how the electrical currents are phased relative to each other. The phase configuration may be either 2/4 or 3-phase. The 3-phase configuration is preferred for the multi-head tool electrode assembly 100 as it requires less volume of wiring for the same amount of power output compared to single-phase or other multi-phase configuration.
[0026] In principle, the plurality of rotors 108 and the plurality of stators 106 functions as in a brushless direct current motor controller (BLDC) and/or a permanent magnet synchronous motor (PMSM). The rotor, which comprises a magnetic material, in the presence of a magnetized first stator, deflects to align with the magnetic field of the first magnetized stator and in turn, comes under the influence of a second magnetized stator and deflects again to align with the magnetic field of the second magnetized stator. The deflections of the rotor under the influence of the magnetic field of the stators result in the rotation of the rotors. The at least one tool electrode 110 which is attached to each of the plurality of rotors 108 rotates along with the rotor.
[0027] According to embodiments of the present disclosure, each of the rotors of the plurality of rotors 108 is arranged in the array 102 to obtain deflections that may result in rotational motion of the plurality of rotors 108, and in turn the at least one tool electrode 110. In one array arrangement, a single rotor can be picturized to be at a center of a square, then four stators are placed at four corners of the square. In another embodiment, the array 102 is formed by placing six stators concentric to a single rotor. The arrangement of the plurality of rotors 108 and hence the at least one tool electrode 110, in the array 102 may correspond to a pattern to be machined on the workpiece. The term, “arrangement” in context to the array 102, corresponds to relative positions of each of the plurality of rotors 108 to the plurality of stators 106, and spacing between each of the plurality of rotors 108 and the plurality of stators 106.
[0028] By varying current from the electric current source to the plurality of stators 106, magnetization of the stators can be controlled which influences the speed of rotation of the rotors. A rotational speed of the at least one tool electrode 110 can be controlled in one instance by varying the current supplied to the windings of the stator. Other parameters that may control the rotational speed of the at least one tool electrode 110 for machining the workpiece include a sequence of magnetization of the stators, spacing between the stators and rotors, and position of the stators relative to the stators in the array 102. In principle, the rotational speed of each of the at least one tool electrode 110 may be controlled individually. However, this may require complex and intricate control systems. In some embodiments, the rotational speed of each of the at least one tool electrode 110 is maintained the same. In one embodiment, the at least one tool electrode 110 has a rotational speed in a range of 500 to 2000 rotations per minute (rpm).
[0029] Commercial BLDC and/or PMSM motors are high-power (high rotations per minute) motors and require a large number of windings on the stator for high-power output making them bulky. In the present disclosure, structures (for example, size of the rod and number of windings) of the plurality of stators 106 and the plurality of rotors 108 are tweaked to miniaturize them. In one instance, the number of windings on the stator is reduced (compared to commercial BLDC and/or PMSM motors) to optimize the rotational speed desired for the at least one tool electrode 110.
[0030] The rotational speed of the at least one tool electrode 110 is controlled for optimizing machining. Further, the translational movement of the at least one tool electrode 110 may be controlled along the three axes by the movement of the mount 104.
[0031] The multi-head tool electrode assembly 100 may further include electronic circuitry (not shown) for driving and/or controlling each of the components for example, the electric current source, the mount 102, the plurality of rotors 108, the plurality of stators 106, the at least one tool electrode 110, either independently or in tandem with the other.
[0032] The multi-head tool electrode assembly 100 may be incorporated into a machining system for machining conducting and non-conducting materials. Examples of machining systems include electrochemical discharge machines, and electrical discharge machines. Further, the multi-head tool electrode assembly 100 may be electrically and magnetically isolated from the machining systems to avoid interference with the workings or working circuitry of the machining system.
[0033] FIG. 2 is an electrochemical discharge machining system 200 in accordance with an exemplary embodiment of the invention. The electrochemical discharge machining system (ECDMs) 200 comprises an electrolytic cell 202. The electrolytic cell includes an electrolytic bath 208 comprising an electrolyte 210, an anode 216, and a multi-head tool electrode assembly 218.
[0034] Referring to FIG. 2, the electrolytic bath 208 comprises the electrolyte 210. The electrolyte 210 is an aqueous alkaline solution. In one embodiment, the aqueous alkaline solution is selected from the group consisting of potassium hydroxide, magnesium hydroxide, sodium hydroxide, calcium hydroxide and any combinations thereof. In preferred embodiments, the electrolyte 210 is sodium hydroxide, potassium hydroxide, or a mixture of both. The concentration or molarity of the electrolyte 210 may be suitably adjusted for optimizing machining condition and/or parameters.
[0035] The walls of the electrolytic bath 208 are made of acrylic. Without any limitation, any suitable non-conducting, thermally stable material may be utilized to form the walls of the electrolytic bath 208. The electrolytic bath 208 can be mounted on a base. The base can be a fixed base or a movable base. The base, if movable, is capable of translational motion in X-Y axes plane.
[0036] The electrolytic cell 202 includes the anode 216. The anode 216 is in contact with the electrolyte 210, and may be completely immersed or partially immersed (as shown in FIG.2) in the electrolyte 210, of the electrolytic bath 208. In one embodiment, the anode 216 is a rectangular strip immersed in the electrolyte 210. The anode 216 may be of any shape such as rod-shaped, or rectangular strip. In one embodiment, the anode 216 comprises graphite, stainless steel, gold, platinum, silver or any combinations thereof. In a preferred embodiment, the anode 216 is composed of stainless steel.
[0037] The multi-head tool electrode assembly 218 (for example, 100 of FIG. 1) of the electrolytic cell 202 includes at least one tool electrode 220 (for example, 110 of FIG.1), as shown in FIG. 2.
[0038] The at least one tool electrode 220 of the multi-head tool electrode assembly 218 typically has a lower surface area than the anode 216. A smaller surface area correspondingly provides for discharge at a lower voltage than when compared to the at least one tool electrode 220 having a larger surface area. In one embodiment, a wire-shape is preferred, although other shapes having smaller surface area may be utilized. The at least one tool electrode 220 comprises copper, tungsten, tungsten carbide, brass, bronze, stainless steel, titanium, aluminum, graphite, or any combinations thereof. In a preferred embodiment, the at least one tool electrode 220 comprises tungsten-carbide.
[0039] The multi-head tool electrode assembly 218 may be attached to a movable arm (not shown). The multi-head tool electrode assembly 218 is operable to move in and out of the electrolytic bath 208 through a controlled motion of the movable arm, to which it is attached, thus making a translational motion in Z-axis plane. The controlled motion of the movable arm can be controlled by an automated control system. In one embodiment, the movable arm forms part of a computer numerical controller (CNC) machine capable of translational motion in 3-dimensional X-Y-Z axes plane.
[0040] A workpiece 222 to be machined is placed in the electrolytic bath 208, between the anode 216 and the multi-head tool electrode assembly 218. Optionally, the workpiece 222 may be placed over a magnetic strip (not shown) to minimize any inductance effect and influence the electrical discharge to be aligned with the magnetic field of the magnetic strip. The workpiece 222, in some instances, may include more than one workpiece.
[0041] In one embodiment, the electrolyte 210 is in constant circulation, circulation of the electrolyte 210 for instance helps in removing debris from the workpiece 222 during machining. The electrolyte 210 may be flowed into the electrolytic bath 208 through an inlet (not shown) placed close to the at least one tool electrode 220. As will be appreciated, circulation of the electrolyte 210 may require additional components such as a circulation pump, storage means, and the like and forms part of the ECDMs 200.
[0042] The workpiece 222 can be an electrically conducting material such as a metal. In certain other embodiments, the workpiece 222 is semi-conducting or non-conducting. Non-limiting examples of the workpiece 222 comprise a metal, silicon, silicon carbide, glass, ceramic, aluminum oxide, silicon nitride, quartz, polymer, polymethyl methacrylate (PMMA), polycarbonate (PC), or any combinations thereof.
[0043] A space between the workpiece 222 and the at least one tool electrode 220 is defined as gap 226, and is critical in obtaining a stable electrochemical discharge whereby quality of machining of the workpiece 222 using ECDMs 200 is achieved. In some embodiments, the gap 226 is maintained at a pre-determined gap. The gap 226, as used herein, refers to the closest distance between the at least one tool electrode 220 and the workpiece 222 at a location of machining within the electrolytic bath 208. The pre-determined gap, as used herein, refers to the closest machining distance between the at least one tool electrode 220 and the workpiece 222. In one embodiment, pre-determined gap is determined prior to each step of operation of the ECDMs 200, as disclosed by IN202241056526 and incorporated herein by reference.
[0044] In an embodiment, where the electrolytic bath 208 is mounted on the base which is movable, the translational motion of the base in X-Y axes plane is controlled along with the movable arm to adjust the gap 226 between the at least one tool electrode 220 and the workpiece 222.
[0045] ECDMs comprises a power source 228. The power source 228 could be an alternating current (AC) or a direct current (DC) capable of providing a pulsating voltage across the at least one tool electrode 220 and the anode 216 to initiate the electrochemical discharge process.
[0046] The electrochemical discharge machining system 200 may comprise an active feedback system (not shown) and a driver system (not shown), as disclosed by IN202241056526, and incorporated herein by reference. The driver system may provide a driver signal to drive the movable arm on which the multi-head tool electrode assembly 218 is attached to, and/or the base such that the gap 226 between the at least one tool electrode 220 and the workpiece 222 is maintained. The driver system may utilize a feedback signal from the feedback system and an input signal from a microprocessor (not shown) to generate the driver signal. The input signal is based on a pattern to be machined on the workpiece. As will be appreciated, the microprocessor may include various other components, for example, power supply, required software and other associated components required to process the input file.
[0047] The input signal is based on an input file including information on a pattern to be machined on the workpiece 222. The input signal may also factor in material properties of the workpiece 222; machining parameters such as machining speed; closest distance to be maintained between the workpiece 222 and the at least one tool electrode 220 given the material properties and the pattern to be machined, for machining the pattern on the workpiece 222. With reference to machining speed, for instance, a material having high shear modulus or “hardness” such as quartz may require a slower machining speed than a material that has low shear modulus or less hardness, such as PMMA. Further, the machining speed may also depend on the pattern to be machined.
[0048] On applying current through power source 228, electrolysis occurs with the release of hydrogen gas bubbles at the at least one tool electrode 220 and oxygen gas at the anode 216. Upon increasing current density, more and more hydrogen gas bubbles are formed which coalesce to form a gas film (dielectric film) over the at least one tool electrode 220 which restricts the contact of the at least one tool electrode 220 and the electrolyte 210 and eventually resulting in electrochemical discharge. To utilize the electrochemical discharge for machining, the workpiece 222, the at least one tool electrode 220 is to be maintained at the gap 226 with the workpiece 222.
[0049] When compared to an ECDM having a single tool electrode, multi-head tool electrode assembly 218 has the advantage of using multiple tool electrodes for different machining tasks on the same workpiece 222, or multiple workpieces. For example, one tool electrode of the at least one tool electrode 220 may be used for roughing while another may be used for finishing. Another advantage of the present disclosure is the reduced wear and tear of the at least one tool electrode 220. By distributing the machining load across multiple tool electrodes, tool wear is distributed evenly prolonging the life of individual electrodes. Another advantage is increase in efficiency as multiple electrodes can be operated simultaneously reducing machining time for manufacturing complex workpiece.
[0050] The voltage applied across the anode 216 and a tool electrode of the at least one tool electrode 220 to initiate the electrochemical discharge process can be controlled, independently, in one instance. In another embodiment, the electrochemical discharge process and hence the machining to form the pattern on the workpiece 222 by maintaining the voltage applied across the anode 216 and all the tool electrodes of the at least one tool electrode 220 is the same.
[0051] FIG. 3 is an electrical discharge machining system 300 in accordance with an exemplary embodiment of the invention. The electrical discharge machining system (EDMs) 300 comprises a cell 302 and a power source 304.
[0052] The cell 302 comprises a dielectric bath 306 comprising a dielectric fluid 308. Examples of dielectric fluid 308 include deionized water, non-conducting lubricating oil, kerosene, and the like.
[0053] A multi-head tool electrode assembly 310 (for example, 100 of FIG. 1) is provided in the cell 302. The multi-head tool electrode assembly 310 includes at least one tool electrode 312. The multi-head tool electrode assembly 310, in one embodiment, is attached to a movable arm 314, as described previously, and is able to move in and out of the dielectric bath 306.
[0054] The at least one tool electrode 312 of the multi-head tool electrode assembly 310 typically has a lower surface area than a counter electrode (for example, a workpiece). A smaller surface area correspondingly provides for discharge at a lower voltage than when compared to the at least one tool electrode 312 having a larger surface area. In one embodiment, a wire-shape is preferred, although other shapes having smaller surface area may be utilized. The at least one tool electrode 312 comprises copper, tungsten, tungsten carbide, brass, bronze, stainless steel, titanium, aluminum, graphite, or any combinations thereof. In a preferred embodiment, the at least one tool electrode 312 comprises tungsten-carbide.
[0055] A conducting workpiece 316 to be machined is provided in the dielectric bath 306 proximate to the multi-head tool electrode assembly 310. In EDMs, the workpiece is conducting and functions as an anode. Optionally, the conducting workpiece 316 may be placed over a magnetic strip (not shown) to minimize any inductance effect and influence the electrical discharge to be aligned with the magnetic field of the magnetic strip. The conducting workpiece 316, in some instances, may include more than one conducting workpiece.
[0056] In one embodiment, the dielectric fluid 308 is in constant circulation, circulation of the dielectric fluid 308 for instance helps in removing debris from the conducting workpiece 316 during machining. The dielectric fluid 308 may be flowed into the dielectric bath 306 through an inlet (not shown) placed close to the at least one tool electrode 312. As will be appreciated, circulation of the dielectric fluid 308 may require additional components such as a circulation pump, storage means, and the like and forms part of the EDMs 300.
[0057] The conducting workpiece 316, in EDMs is composed of an electrically conducting material. Non-limiting examples of the conducting workpiece 316 comprise a metal, tool steel, stainless steel, superalloys, Inconel, Hastelloy, Waspaloy, titanium alloys, polycrystalline diamond, conducting ceramics, graphite, conducting polymers, or any combinations thereof.
[0058] A space between the conducting workpiece 316 and the at least one tool electrode 312 is defined as spark gap 318, and is critical in obtaining a stable electrical discharge whereby quality of machining of the conducting workpiece 316 using EDMs 300 is achieved. In some embodiments, the spark gap 318 is maintained at a pre-determined gap. The spark gap 318, as used herein, refers to the closest distance between the at least one tool electrode 312 and the conducting workpiece 316 at a location of machining within the dielectric bath 306. The pre-determined gap, as used herein, refers to the closest machining distance between the at least one tool electrode 312 and the conducting workpiece 316. In one embodiment, pre-determined gap is determined prior to each step of operation of the EDMs 300.
[0059] The power source 304 could be an alternating current (AC) or a direct current (DC) power source capable of providing a pulsating voltage across the at least one tool electrode 312, and the conducting workpiece 316 to provide electrical discharge.
[0060] The electrical discharge machining system 300 may comprise an active feedback system (not shown) and a driver system (not shown). The driver system may provide a driver signal to drive the movable arm 314 on which the multi-head tool electrode assembly 310 is attached to, such that the spark gap 318 between the at least one tool electrode 312 and the conducting workpiece 316 is maintained. The driver system may utilize a feedback signal from the feedback system and an input signal from a microprocessor (not shown) to generate the driver signal. The input signal is based on a pattern to be machined on the conducting workpiece 316. As will be appreciated, the microprocessor may include various other components, for example, power supply, required software and other associated components required to process the input file.
[0061] The input signal is based on an input file including information on a pattern to be machined on the conducting workpiece 316. The input signal may also factor in material properties of the conducting workpiece 316; machining parameters such as machining speed; closest distance to be maintained between the conducting workpiece 316 and the at least one tool electrode 312 given the material properties and the pattern to be machined, for machining the pattern on the conducting workpiece 316.
[0062] On applying current through the power source 304, electrical discharge occurs at the spark gap 318 between the at least one tool electrode 312 and the conducting workpiece 316 to generate high thermal energy (high temperature) which melts away material from the conducting workpiece 316. By controlling the spark gap 318, a desired pattern may be machined on the conducting workpiece 316.
[0063] The EDMs 300 including the multi-head tool electrode assembly 310 can perform multiple machining tasks on the same conducting workpiece 316, or multiple conducting workpieces simultaneously in a single pass. For example, one tool electrode of the at least one tool electrode 312 may be used for roughing while another may be used for finishing. Another advantage of the present disclosure is the reduced wear and tear of the at least one tool electrode 312. By distributing the machining load across multiple tool electrodes, tool wear is distributed evenly prolonging the life of individual electrodes.
[0064] It is understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined in the appended claims. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" is used as the plain-English equivalent of the respective term "comprising" respectively.
,CLAIMS:1. A multi-head tool electrode assembly (100) comprising:
an array (102) comprising a plurality of stators (106) and a plurality of rotors (108) provided on a mount (104), wherein the plurality of rotors (108) in the array (102) is positioned relative to the plurality of stators (106) to enable rotation of the plurality of rotors (108) on application of voltage to the plurality of stators (106); and
at least one tool electrode (110) mechanically coupled to the plurality of rotors (108) to enable rotation of the at least one tool electrode (110).

2. The multi-head tool electrode assembly (100) as claimed in claim 1, wherein the mount (104) is retractable.

3. The multi-head tool electrode assembly (100) as claimed in claim 1, wherein the at least one tool electrode (110) has a rotational speed in a range of 500 to 2000 rotations per minute (rpm).

4. The multi-head tool electrode assembly (100) as claimed in claim 1, wherein the at least one tool electrode (110) comprises copper, tungsten, tungsten carbide, brass, bronze, stainless steel, titanium, aluminum, graphite, or any combinations thereof.

5. The multi-head tool electrode assembly (100) as claimed in claim 1, wherein a number of stators in the plurality of stators (106) is in a range of 5 to 9000.

6. The multi-head tool electrode assembly (100) as claimed in claim 1, wherein a number of rotors in the plurality of rotors (108) is in a range of 2 to 3000.

7. A machining system for tooling comprising the multi-head tool electrode assembly as claimed in claim 1.

8. An electrochemical discharge machining system (200) comprising:
a multi-head tool electrode assembly (218), wherein the multi-head tool electrode assembly (218) comprises;
an array comprising a plurality of stators and a plurality of rotors provided on a mount, wherein the plurality of rotors in the array is positioned relative to the plurality of stators to enable rotation of the plurality of rotors on application of voltage to the plurality of stators; and
at least one tool electrode (220) mechanically coupled to the plurality of rotors to enable rotation of the at least one tool electrode (220);
an electrolytic bath (208) comprising an electrolyte (210);
an anode (216) in contact with the electrolyte (210);
a workpiece (222) to be machined in the electrolytic bath (208) and placed between the anode (216) and the at least one tool electrode (220); and
a power source (228) to provide voltage across the anode (216) and the least one tool electrode (220) to provide an electrical discharge for machining the workpiece (222).

9. The electrochemical discharge machining system (200) as claimed in claim 8, wherein the electrolyte (210) comprises an aqueous alkaline solution selected from the group consisting of potassium hydroxide, magnesium hydroxide, sodium hydroxide, calcium hydroxide, and any combinations thereof, wherein the anode (216) comprises graphite, stainless steel, gold, platinum, silver or any combinations thereof, and wherein the at least one tool electrode (220) comprises copper, tungsten, tungsten carbide, brass, bronze, stainless steel, titanium, aluminum, graphite or any combinations thereof.

10. The electrochemical discharge machining system (200) as claimed in claim 8, wherein the workpiece (222) comprises a metal, silicon, silicon carbide, glass, ceramic, aluminum oxide, silicon nitride, quartz, polymer, polymethyl methacrylate (PMMA), polycarbonate (PC) or any combinations thereof.

11. An electrical discharge machining system (300) comprising:
a multi-head tool electrode assembly (310), wherein the multi-head tool electrode assembly (310) comprises;
an array comprising a plurality of stators and a plurality of rotors provided on a mount, wherein the plurality of rotors in the array is positioned relative to the plurality of stators to enable rotation of the plurality of rotors on application of voltage to the plurality of stators; and
at least one tool electrode (312) mechanically coupled to the plurality of rotors to enable rotation of the at least one tool electrode (312);
a conducting workpiece (316) to be machined in a dielectric bath (306) proximate to the at least one tool electrode (312); and
a power source (304) to provide voltage across the conducting workpiece (316) and the least one tool electrode (312) to provide an electrical discharge for machining the conducting workpiece (316).