Method and apparatus for optimized wire electrical discharge machining - Patents.com

Abstract

1. An electric discharge machining method for an electric discharge machining machine using an electric discharge machining wire packaged on a reel, the reel being provided with an identification data medium 11 carrying embedded identification data ME relating to said electric discharge machining wire and embedded control data CE linked to the embedded identification data ME by a control function F, - specific optimized machining parameters PSP and a control function F are pre-stored in the electric discharge machining machine, - the electric discharge machining machine receives read-out control data CL and read-out identification data ML from the identification data medium 11, - the electric discharge machining machine checks to see whether the read-out identification data ML and the read-out control data CL are linked by the control function F, - the electric discharge machining machine induces or allows machining as a function of said specific optimized machining parameters PSP only if the read-out identification data ML and the read-out control data CL are linked by said control function F.

Description

[Technical field]

[0001] The invention concerns an electric discharge machining apparatus in which a continuous metal wire of small radius is unwound from a reel on which it is packaged and passes through a machining zone filled with a suitable dielectric in an electric discharge machining machine. In the machining zone, a section of the wire is held by a guide adjacent to a workpiece, which is itself electrically conductive. A current generator is connected between the wire and the workpiece, generating an electric arc between the wire and the workpiece. The electric arc induces erosion of the wire and of the workpiece. To compensate for the erosion of the wire, the wire is displaced continuously in the longitudinal direction of the wire in the machining zone. Following the erosion generated on the workpiece, the wire is progressively displaced by the electric discharge machining machine towards the workpiece, thus generating a notch on the workpiece by material removal. [Background technology]

[0002] The performance characteristics of the machining carried out by EDM depend on a number of parameters, and in particular on: - machining parameters determined by the EDM machine, which may include the power delivered by the current generator, the rate of longitudinal displacement of the wire, the longitudinal mechanical tension applied to the wire in the machining zone, the agitation of the dielectric in the machining zone, the functional offset between the wire and the workpiece, more commonly referred to simply as "offset"; - parameters related to the structure or quality of the wire itself, which may include the type of wire, its length, the material of which it is made, the pressure it has withstood since it was manufactured, the power it can withstand during processing without breaking, the structure and composition of the wire itself, the mechanical tension it can withstand without breaking, the mechanical properties of the wire that determine how easily or more easily the wire can be introduced into the processing zone and into the guides of the EDM machine at the start of processing; - Parameters relating to the structure or quality of the workpiece, which may include the type of workpiece, the structure and composition of the workpiece itself.

[0003] Based on these parameters, the removal of material on the workpiece may be more or less rapid, characterized by the processing speed, or rate of penetration of the wire into the workpiece.

[0004] Based on these parameters, the machining performed may be more or less precise, as characterized by the precision of the notch created on the workpiece.

[0005] Or, based on these parameters, the machining performed may be characterized by the surface finish of the cut face of the workpiece thus obtained.

[0006] Typically, during machining of a workpiece with a particular type of EDM wire, the user is guided by the machine in the selection of appropriate machining parameters to be used by the EDM machine to obtain one or more particular machining performance characteristics. A set of machining parameters is determined by the manufacturer of the EDM machine for a number of machining conditions. A skilled user can in principle select the appropriate machining parameters or modify the machining parameters suggested to him by the machine in order to improve the machining performance level.

[0007] However, to obtain a true optimization of the individual machining performance characteristics obtained by each type of EDM wire, it seems necessary to first carry out a large number of machining tests by varying the machining parameters, the workpieces, and the workpieces to obtain a specific set of optimized machining parameters, which is the first difficulty.

[0008] If machining is then carried out by using the same set of specific optimized machining parameters, but with an EDM wire that is only slightly different, experience shows that the machining results obtained are disappointing and far from optimized, which amounts to a second difficulty.

[0009] The upshot of this is that to obtain true optimization of individual machining performance characteristics, an EDM machine should explicitly associate an EDM wire with optimized machining parameters that are specific to that EDM wire and that have given optimized results after numerous prior tests.

[0010] For this, on the one hand, the EDM machine needs to know with certainty and without risk of error the type of EDM wire that the user has installed for machining, and further needs to contain a memory of a set of optimized machining parameters specific for this type of EDM wire.

[0011] When the user himself introduces into the EDM machine the identification data relating to the EDM wire and the selection of machining parameters, errors can occur, in particular due to erroneous input or due to erroneous read-out, which does not make it possible to guarantee that an optimized machining result will be obtained.

[0012] In the document DE 10 04 06 13 A1 it was proposed to automate the introduction of identification data relating to the EDM wire into the EDM machine. The EDM wire is for that purpose packaged on a reel which is itself provided with a radio tag capable of communicating with a data reader device associated with the EDM machine, typically at a frequency of 13.56 MHz. The EDM machine can then itself adapt its machining parameters by taking into account the identification data emanating from the radio tag.

[0013] However, experience has shown that EDM machines generate electromagnetic interference that can prevent correct reading of the identification data present on the radio tag: the 13.56 MHz frequency can be disrupted by several EDM generators, either on the wire-based EDM machine or on nearby EDM machines, so that read and / or write errors can exist despite the communication protocol used.

[0014] Data transmission protocols can in fact detect errors between the sender and the EDM machine. However, they cannot detect if erroneous identification data has been previously written. Such errors may consist, for example, in erroneous writing caused by errors in the software of the EDM machine itself during prior use of the reel, which is common. Another example is writing errors created in the handling of the reel (storage, removal from storage, weighing, etc.) prior to mounting the reel on the EDM machine.

[0015] It will be understood that erroneous reading of the identification data relating to the EDM wire or the presence of erroneous identification data may lead to breakage of the EDM wire or to disappointing machining results due to the application of inappropriate machining parameters. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] International Publication No. 2017 / 056045 [Patent Document 2] U.S. Pat. No. 4,724,427 [Non-patent literature]

[0017] [Non-Patent Document 1] https: / / encode-decode.com / aes-128-cbc-encrypt-online Summary of the Invention [Problem to be solved by the invention]

[0018] One issue addressed by the present invention is to avoid the drawbacks of known EDM methods and apparatus, and in particular to avoid identification errors associated with EDM wires that are loaded into EDM machines for machining tasks.

[0019] Another issue addressed by the present invention is to ensure that as satisfactory a machining as possible will be obtained in the use of an EDM wire in an EDM machine. The aim is then to limit the effect of possible storage or read-out errors, i.e. to obtain optimal machining results, whether the wire reel is clearly identified or not.

[0020] Another object of the present invention is to ensure that individual types of wire are used in combination with individual techniques, and vice versa, to obtain standardized processing results.

[0021] To this end, the present invention aims, on the one hand, to automatically ensure that optimized machining will be obtained whenever an individual type of EDM wire, and therefore having individual configurations and / or properties, can be unambiguously associated in an EDM machine with machining parameters that are specific to that EDM wire and that have given optimized results in previous tests.

[0022] Preferably, the goal of the present invention is to optimize machining with certainty, if necessary taking into account historical data regarding the use of the EDM wire.

[0023] In addition, the present invention can, on the other hand, aim to automatically ensure that machining with as little degradation as possible will be obtained when the EDM wire cannot be clearly associated with specific machining parameters in the EDM machine that have given optimized results in numerous previous tests. [Means for solving the problem]

[0024] To achieve these and other objects, according to a first aspect, the present invention provides an electric discharge machining method for an electric discharge machining machine using an electric discharge machining wire packaged on a reel, wherein an identification data medium in the form of an RFID radio frequency identification tag data carrier is associated with said reel forming an assembly, and in which embedded identification data relating to said electric discharge machining wire are stored in digital form, (a) receiving, from an identification data medium, retrieved identification data representative of embedded identification data contained within the identification data medium; (b) a method for electric discharge machining, in which the electric discharge machining machine adapts the machining parameters by taking into account, inter alia, the read-out identification data emanating from an identification data carrier of the reel used for machining, - specific optimized machining parameters are previously determined by machining tests carried out with the same type of EDM wire as that packed on a reel, for example by carrying out said tests with different machining parameters and by selecting the parameters which provided the best machining performance in said tests as specific optimized machining parameters, - said specific optimized machining parameters and control functions are prestored in a memory means of the electric discharge machining machine, - the embedded control data are predetermined by a control function and stored on an identification data medium in such a way that they are linked to the embedded identification data of the EDM wire, Before step (b), - the electric discharge machining machine receives the read control data from the identification data medium, - the electric discharge machining machine checks to see whether the retrieved identification data and the retrieved control data are linked by a control function; - the electric discharge machining machine triggers or allows machining according to said specific optimized machining parameters only if the retrieved identification data and the retrieved control data are linked by said control function. A method for electric discharge machining is proposed.

[0025] In the present description and in the claims, the expression "associated" means that the reel and the identification data medium are distributed in such a way that they can be jointly used by the EDM machine, thus forming an assembly. A user uses the reel in order to place it in the EDM machine, and uses the identification data medium in order for it to be read by the EDM machine. For example, the reel and the identification data medium can be packaged together, and the identification data medium can be fixed (e.g. glued) onto a flange of the reel or onto a pouch that contains the reel, or fixed or placed in a container that contains the reel.

[0026] In an RFID tag, as in a computer or EDM machine controller, information such as values, text data, and mathematical functions are stored in a numeric form, usually a two-digit code, and stored in a specific location. Each piece of information or data can then be interpreted as an integer ME. In this description and in the claims, the term "control function F" refers to any mathematical calculation that can be applied to this integer ME to uniquely generate another integer CE that can then be used as control data.

[0027] Preferably, the electric discharge machining method further comprises: - the standard machining parameters are determined in advance by machining tests carried out with various electric discharge machining wires, for example by carrying out said tests with different machining parameters and by selecting as standard parameters those parameters which, on average for the various electric discharge machining wires, provided a satisfactory machining performance during said tests, - said standard machining parameters are pre-stored in a memory means of the electric discharge machining machine, - if the electric discharge machining machine determines that the retrieved identification data and the retrieved control data are not linked by said control function, the electric discharge machining machine triggers or allows machining according to said standard machining parameters. Something like that.

[0028] In all cases, - applying a control function to the embedded identification data associated with the EDM wire in determining the embedded control data; - applying, by the electric discharge machining machine after reception of the read control data, a control function to the read identification data in order to deduce verification data from the read identification data, and comparing, by the electric discharge machining machine, the read control data received from the identification data medium with said verification data. if the verification data coincides with the retrieved control data, the electric discharge machine considers that the retrieved identification data and the retrieved control data are linked by said control function. It may be advantageous to provide

[0029] instead, - applying a control function to the embedded identification data associated with the EDM wire in determining the embedded control data; - applying, by the electric discharge machining machine after receiving the read control data, an inverse of the control function to the embedded control data in order to deduce verification data from the embedded control data, and comparing, by the electric discharge machining machine, the read identification data received from the identification data medium with said verification data; if the verification data corresponds to the retrieved identification data, the electric discharge machine considers that the retrieved identification data and the retrieved control data are linked by said control function. It may be advantageous to provide

[0030] The control function may advantageously be a private key cryptographic function which performs the encryption.

[0031] The identification data medium is a radio frequency tag in which embedded identification data and embedded control data are stored in digital form, as well as in which historical data regarding the use of the EDM wire collected during previous sequences of use of the wire being trimmed on a reel can be recorded.

[0032] According to a second aspect, the invention relates to an electric discharge machining machine suitable for implementing the above mentioned machining method, comprising: - the electric discharge machining machine forms an assembly with a reel on which the wire is packaged, and with a data reader device capable of reading embedded identification data stored in digital form in an identification data carrier in the form of an RFID radio tag, and of transmitting the read identification data to the electric discharge machining machine, - the data reader device is further capable of reading embedded control data carried by the reel identification data medium and transmitting those embedded control data to the EDM machine; the electric discharge machining machine comprises storage means in which specific optimized machining parameters and control functions are stored, - the electric discharge machining machine comprises electric discharge machining wire recognition means comprising calculation means and a stored computer program comprising a recognition sequence capable of verifying whether the retrieved identification data and the retrieved control data are linked by said control function, - an electric discharge machining machine comprising control means and a stored computer program comprising a control sequence capable of inducing or allowing machining according to said specific optimized machining parameters only if the retrieved identification data and the retrieved control data are linked by a control function, We propose an electric discharge machining machine.

[0033] According to a third aspect, the invention proposes a wire reel for electrical discharge machining suitable for the realization of the machining method described above, in which an identification data medium in the form of an RFID radio tag is associated with the wire reel forming an assembly, the data of which can be read by a data reader device associated with the electrical discharge machining machine, the identification data medium carrying embedded identification data relating to the wire, the identification data medium further carrying embedded control data linked to the embedded identification data by a control function, the control function being a mathematical calculation that can be applied to the embedded identification data considered as an integer in order to uniquely generate the embedded control data.

[0034] Preferably, within the identification data medium the control function is a private key encryption function which encrypts.

[0035] The identification data medium is a radio frequency tag in which embedded identification data and embedded control data are stored in digital form, as well as in which historical data regarding the use of the EDM wire collected during previous sequences of use of the wire being trimmed on a reel can be recorded.

[0036] According to a fourth aspect, the invention proposes an apparatus suitable for implementing the electric discharge machining method. Such an apparatus comprises: - electrical discharge machine, - EDM wire packaged on reels, - an identification data medium in the form of an RFID radio tag, which is associated with the reel, forming an assembly therewith and which is accessible for reading out the data which it carries, - embedded identification data of said wire, carried by an identification data medium; - a data reader device forming a functional unit with the electric discharge machining machine, capable of reading out the embedded identification data carried by the identification data medium of the reel and of transmitting the read out identification data to the electric discharge machining machine. Equipped with - the embedded control data are furthermore retained on an identification data medium, - the data reader device is further capable of reading embedded control data carried by the identification data medium of the reel and transmitting the read control data to the EDM machine; the electric discharge machining machine comprises storage means in which the control functions and the specific optimized machining parameters are stored, said parameters being determined in advance by machining tests carried out with an electric discharge machining wire of the same type as the type of the electric discharge machining wire packed on a reel, for example by carrying out said tests with different machining parameters and by selecting as the specific optimized machining parameters the parameters which provided the best machining performance in said tests, - the electric discharge machining machine comprises electric discharge machining wire recognition means comprising calculation means and a stored computer program comprising a recognition sequence capable of verifying whether the retrieved identification data and the retrieved control data are linked by said control function, - an electric discharge machining machine comprising control means and a stored computer program comprising a control sequence which is capable of inducing or allowing machining according to said specific optimized machining parameters only if the read-out identification data and the read-out control data are linked by a control function.

[0037] Preferably, the electric discharge machining apparatus comprises: - standard machining parameters are previously determined by machining tests carried out with various electric discharge machining wires, for example by carrying out said tests with different machining parameters and by selecting as standard parameters those parameters which, on average for the various electric discharge machining wires, provided a satisfactory machining performance during said tests, said parameters being further stored in a memory means of the electric discharge machining machine, if the retrieved identification data and the retrieved control data are not linked by said control function, the control sequence of the electric discharge machine triggers or allows machining according to said standard machining parameters. Something like that.

[0038] In such an EDM apparatus, the identification data medium is a radio frequency tag in which the embedded identification data and the embedded control data are stored in digital form, and the data reader device is a radio frequency communication device capable of communicating with the radio frequency tag.

[0039] Other objects, features and advantages of the present invention will become apparent from the following description of specific embodiments, given in conjunction with the accompanying drawings. [Brief description of the drawings]

[0040] [Figure 1] 1 is a schematic view of an electric discharge machining machine in the process of machining a workpiece by means of a wire packaged on a reel according to an embodiment of the present invention; [Diagram 2]FIG. 2 is a diagram illustrating diagrammatically an identification data medium of the passive radio tag type according to a first embodiment of the invention, communicating by radio frequency with a data reader device associated with or implemented in an electric discharge machining machine; [Diagram 3] FIG. 2 shows a schematic illustration of an active or semi-active radio tag type identification data medium according to a second embodiment of the present invention, communicating by radio frequency with a data reader device associated with or implemented in an electric discharge machining machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Consider first Fig. 1, which illustrates an electrical discharge machining apparatus according to an embodiment of the invention. The machining apparatus generally comprises an electrical discharge machining machine 1, which is provided with a machining area 2 filled with a suitable liquid dielectric. The machining area 2 is shaped and structured to receive and hold a workpiece 3. An electrical discharge machining wire 4, packaged on a reel 5, is unwound from the reel 5 by running over a guide 6 of the electrical discharge machining machine 1, which holds the electrical discharge machining wire 4 in position and drives the electrical discharge machining wire 4 longitudinally at a suitable scrolling speed, as illustrated by arrow 7. The electrical discharge machining wire 4 runs through the machining area 2, where it is held adjacent to the workpiece 3 according to a suitable functional offset.

[0042] The electric discharge machining machine 1 further comprises a current generator 8 connected between the electric discharge machining wire 4 and the workpiece 3 for generating an electric arc between the electric discharge machining wire 4 and the workpiece 3 .

[0043] In operation, the electric arc induces erosion of the EDM wire 4 and of the workpiece 3. The constant longitudinal scrolling 7 of the EDM wire 4 in the machining zone 2 makes it possible to avoid breakage of the EDM wire 4 as a result of the erosion induced on the wire by the electric arc. However, the erosion induced on the workpiece 3 by the electric arc amounts to a removal of material, which makes it possible to create a notch 10 on the workpiece 3 by a gradual relative displacement of the EDM wire 4 towards the workpiece 3, for example as illustrated by the arrow 9.

[0044] In the machining zone 2, the EDM wire 4 must be kept tight and taut by longitudinal mechanical traction provided by the guides 6 in order to maintain a straight profile and a stable and defined geometric position, which ensure good geometry of the notch 10 to be made on the workpiece 3.

[0045] At the start of machining, the free end of the EDM wire 4 has to be introduced into the guide 6 and into the machining area 2. Typically, the EDM machine 1 includes a sequence of movements that ensures automatic introduction of the wire. However, the sequence of movements requires that the EDM wire 4 has satisfactory straightness and rigidity properties, so that guiding of the free end of the EDM wire 4 is ensured when the guide 6 holds the wire only by its mid-section remote from the free end of the wire.

[0046] An electronic control circuit 17 drives the active members of the EDM machine 1 to set machining parameters such as the power delivered by the current generator 8, the rate of longitudinal displacement 7 of the wire, the longitudinal mechanical tension applied to the wire in the machining zone 2, the agitation of the dielectric in the machining zone 2, and the functional offset between the wire 4 and the workpiece 3.

[0047] According to the invention, the machining device further comprises identification means enabling automatic identification of the EDM wire 4 packaged on the reel 5 and optimized control means suitable for allowing or inducing the actuation of functional members of the EDM machine 1 as a function of the EDM wire 4 as identified, so as to enable optimized machining of the workpiece 3 with this EDM wire 4.

[0048] In the embodiment illustrated in Figures 1 to 3, the identification means in particular comprise an identification data medium 11 fixed onto the flange of the reel 5, which, on the one hand, carries embedded identification data ME relating to the EDM wire 4, and, on the other hand, carries embedded control data CE which is linked to the embedded identification data ME by means of a control function F, as will be explained below.

[0049] The identification data medium 11 cooperates with a data reader device 13 which is functionally associated with the electric discharge machining machine 1 via a wireless link 100 which enables communication between the identification data medium 11 and the data reader device 13 .

[0050] 2 and 3 illustrate, by way of example, two embodiments of an identification device according to the invention.

[0051] In Fig. 2, the identification data medium 11 is a passive radio tag comprising an antenna 11a and a power supply circuit 11b capable of harvesting a portion of the electrical energy picked up by the antenna 11a in order to generate a power supply voltage for powering the other electronic circuits of the radio tag. An electronic processing circuit 11c receives an electronic request signal 14c picked up by the antenna 11a, communicates with a storage circuit 11d containing embedded identification data ME and embedded control data CE, and generates, as a function of the electronic request signal 14c, an electronic response signal 14d which it transmits by the antenna 11a. For example, immediately after receiving an electronic request signal 14c requesting the communication of an identification, the passive radio tag 11 returns a response signal 14d containing said embedded identification data ME and said embedded control data CE.

[0052] In this case, the data reader device 13 is an active device, a radio frequency transmitter making it possible to remotely activate the radio tag 11. The data reader device 13 comprises an antenna 13d and an electronic circuit 13e making it possible, on the one hand, to generate a request signal 14c to be transmitted by the antenna 13d to the radio tag 11, and, on the other hand, to process a response signal 14d emitted by the radio tag 11 and picked up by the antenna 13d. The wireless link 100 is a radio link.

[0053] Exemplary embodiments of a radio tag and of a data reader device are described in US Pat. No. 5,399,633.

[0054] In Fig. 3, the identification data medium 11 is again an active or semi-active radio tag in which are present the main elements of the embodiment of Fig. 2, and in particular an antenna 11a, a power supply circuit 11b, an electronic processing circuit 11c, a memory circuit 11d, which have the same functions as those of the embodiment of Fig. 2. In Fig. 3, the identification data medium 11 further comprises an embedded electrical energy source 15 capable of supplying electrical energy to the electronic processing circuit 11c and the memory circuit 11d instead of or in addition to the electrical energy captured by the antenna 11a.

[0055] In this case, the identification data medium 11 further comprises embedded sensors, for example four embedded sensors 16a, 16b, 16c, 16d, which respectively supply to the electronic processing circuit 11c a signal which is an embodiment of the acceleration endured by the reel 5 supporting the wire 4 and the identification data medium 11, a signal which is an embodiment of the ambient temperature, a signal which is an embodiment of the ambient relative humidity and a signal which is an embodiment of the weight of the reel 5.

[0056] The electronic processing circuitry 11c is driven by an embedded computer program that includes a storage sequence for scanning and storing signals produced by the embedded sensors 16a, 16b, 16c, and 16d in the storage circuitry 11d.

[0057] 3, the data reader device 13 is furthermore an active device, transmitting radio frequencies making it possible to remotely activate the radio tag 11 if necessary, and comprising an antenna 13d and an electronic circuit 13e, on the one hand, for generating a request signal 14c sent to the radio tag 11, and on the other hand, for processing a received signal 14d emanating from the radio tag 11 and picked up by the antenna 13d. The wireless link 100 is a radio link.

[0058] The control circuit 17 of the electric discharge machine 1 includes a calculation means 17a, such as a processor, and a storage means 17b.

[0059] The storage means 17b of the control circuit 17 contains sets of machining parameters, each set of machining parameters preferably intended to be used for an individual type of machining with an individual type of EDM wire. In particular, the storage means 17b of the control circuit 17 contains one or more sets of specific optimized machining parameters PSP, each determined after previous machining tests carried out with the exact same type of EDM machine 1, using the exact same type of EDM wire M. In the storage means 17b of the control circuit 17, the sets of specific optimized machining parameters PSP are associated, fully or partially, with identification data relating to the corresponding EDM wire M.

[0060] The memory means 17b of the control circuit 17 furthermore contains a computer program P implemented by the calculation means 17a, which makes it possible, inter alia, to drive the active members of the EDM machine 1 according to a selected set of machining parameters in order to carry out machining of the workpiece 3.

[0061] The computer program P of the control circuit 17 of the electric discharge machining machine 1 comprises at least one sequence for downloading the embedded identification data ME and the embedded control data CE carried by the identification data medium 11. As is well known in computer technology, the download sequence is programmed to recognize the identification data and the control data by their specific storage location addresses in the RFID radio tag. The download sequence drives the data reader device 13 to generate request signals 14c which it sends to the identification data medium 11, which then returns a message 14d to the data reader device 13. After any possible electromagnetic interference, the message 14d as received by the data reader device 13 arrives at the control circuit 17 in the form of the read identification data ML and in the form of the read control data CL.

[0062] The computer program P of the control circuit 17 of the electric discharge machining machine 1 contains at least one sequence for adapting the machining parameters, taking into account in particular the read-out identification data ML and the read-out control data CL originating from the identification data medium 11 of the reel 5 used for machining. In that way, the device according to the invention makes it possible to automate the adaptation of the electric discharge machining parameters of the electric discharge machining machine 1 as a function of the specific capacity of the electric discharge machining wire 4 used. For example, the adaptation sequence may modify or limit the parameters of the mechanical tension of the electric discharge machining wire 4 in the machining area 2, the intensity of the current flowing through the electric discharge machining wire 4 in the machining area 2, the rate of the longitudinal displacement 7 of the electric discharge machining wire 4 in the machining area 2, the stirring of the dielectric in the machining area 2, the transverse displacement 9 of the electric discharge machining wire 4 in the machining area 2, the maintenance of the functional offset between the electric discharge machining wire 4 and the workpiece 3.

[0063] The downloading of data relating to the EDM wire 4 can be straightforward by simple interrogation of the identification data medium 11, provided that it contains all of the necessary data.

[0064] Alternatively, the downloading of data relating to the EDM wire 4 may be partly indirect, the download sequence then including a downloading of at least the identity of the manufacturer of the wire 4 and the serial number of the reel 5 through interrogation of the identification data medium 11, as well as a sequence of automatic downloading of data relating to the reel 5 of the wire 4 from the manufacturer's computer server by interrogating the manufacturer's computer server via the Internet by means of information relating to the identity of the manufacturer of the wire 4 and the serial number of the reel 5.

[0065] According to the invention, the computer program P of the control circuit 17 of the EDM machine 1 includes a separate sequence of identification of the EDM wire 4 which proceeds with a more precise identification of the EDM wire 4 not only by taking into account the read-out identification data ML as received from the identification data medium 11, but also by taking into account the control function F described above and by taking into account the read-out control data CL as received from the identification data medium 11.

[0066] The control function F is neither stored in plain text nor explained in the information carried by the identification data medium 11. This control function F is used by the supplier of the EDM wire 4 packaged on the reel 5 to generate the embedded control data CE from the embedded identification data ME. In that way the embedded identification data ME and the embedded control data CE are linked to each other by said control function F.

[0067] In contrast, the control function F is itself stored in storage means 17 b provided in the control circuit 17 of the EDM machine 1 .

[0068] On the identification data medium 11, the embedded identification data ME may notably be stored in the form of a sequence of binary signals (0 or 1), i.e. in the form of natural integer numbers written in binary notation. According to a first particularly simple example, proposed to facilitate the understanding of the invention, the control function F may then consist of a NOT function which inverts each binary signal of the embedded identification data ME, so that a binary 0 signal of the embedded identification data ME becomes a binary 1 signal in the embedded control data CE, while a binary 1 signal of the embedded identification data ME becomes a binary 0 signal in the embedded control data CE.

[0069] According to a second, somewhat more complicated example, the control function F may give the remainder C of a Euclidean division of the embedded identification data ME by an integer number K, which itself consists of a private encryption key.

[0070] For example, it is possible to choose a key K=19. By applying this function F to the embedded identification data ME having the value 99, the embedded control data CE then has the value 4, since 99=19×5+4.

[0071] According to a third example, on the identification data medium 11, the embedded identification data ME can be coded in a character string according to the ASCII coding computer standard. The control function F can be the encryption function known as "aes-128-cbc" by using a private encryption key K, which itself can be encoded according to the ASCII coding computer standard. The use of this function can be easily realized by calculations carried out on the website: http: / / www.ieee.org / en / US / 10 / 101 / 1010128 / 1010128.

[0072] For example, it is possible to choose a key K="Thermocompact". By applying this encryption function F to the embedded identification data ME composed of the sequence "Fil Thermo SA 900 N / mm2 0.25mm produit le 13 / 08 / 2020 sous le numero 123456789", the following embedded control data CE is obtained: "mUcNi+tUBbdONTrx8TmY76nBrtaqx5Cf1RZKdMbVMjf+POZK+aHmLFqE09FufsQC0bGC89bG9D5pUdb7DY+euaftyLyZQJrExo5GOKGuDcI=".

[0073] Immediately after receiving the read-out identification data ML and the read-out control data CL, the EDM wire 4 identification sequence can apply a control function F to the read-out identification data ML, thus generating verification data V, and can compare the verification data V and the read-out control data CL with each other. If the data match, the identification sequence considers that the read-out identification data ML and the read-out control data CL are linked by the control function F and, as a consequence, that the read-out identification data ML matches the embedded identification data ME and that the embedded identification data is correct.

[0074] Instead, immediately after receiving the read identification data ML and the read control data CL, the EDM wire 4 identification sequence is determined by the inverse function F of the control function F. -1 to the read control data CL, thus generating verification data W, which can be compared with the read identification data ML received from the identification data medium 11. If they match, the identification sequence considers that the read identification data ML and the read control data CL are linked by the control function F, and, as a consequence, that the read identification data ML matches the embedded identification data ME, and that the embedded identification data is correct.

[0075] One benefit of using a private key encryption based control function F is that it further reduces the risk of EDM wire identification errors considerably. Indeed, in the third example above, if an error had been introduced into the embedded identification data ME, or if a transmission disturbance had introduced a slight alteration between the embedded identification data ME and the read identification data ML, the verification data V would be very different from the read control data CL, which would make it easier to recognize. In this particular case, if the sequence "SA" of the embedded identification data ME had been transformed into the sequence "SB" in the retrieved identification data ML by replacing only the letters "A" by the letter "B", the verification data V would be "u3hROePgvtGCCG3Ji2XFKyRElPfJSB6ZnF23gn7KrK4NqOD7WuH8t9QargS1dAiOG52mCHcoqPACtkE3vcHXspFJ8f3uP5aKTUnKGaFZeXg=". V and CL are completely different. The specific optimized processing parameters PSP can therefore be applied with confidence when the verification data V matches the embedded control data CE.

[0076] According to the invention, the computer program P of the control circuit 17 of the EDM machine 1 further comprises individual permission sequences according to which the EDM machine 1 allows or induces machining with the EDM wire 4 by applying specific optimized machining parameters PSP if permission conditions are fulfilled.

[0077] According to a first permission condition, the identification sequence requires that the read identification data ML be considered to match the embedded identification data ME.

[0078] According to a second permission condition, the read-out identification data ML must correspond to essential identification data of one of the types of EDM wire M itemized in the memory means 17b provided in the control circuit 17 of the EDM machine 1.

[0079] When the first and second permission conditions are satisfied, an individual permission sequence permits or induces machining with the EDM wire 4 by applying specific optimized machining parameters PSP, which are pre-stored in memory means 17b provided in the control circuit 17.

[0080] With the identification of the EDM wire 4 ensured thanks to the control means realised above, the user can be sure that he will obtain optimised machining results whenever the EDM machine 1 automatically triggers or allows optimised machining.

[0081] Another benefit consists in that the machining result is not significantly worsened when the EDM machine 1 automatically assigns a different set of machining parameters for use with a given EDM wire 4. In fact, it has been found that the use of standard machining parameters leads to better machining results than the use of specific optimized machining parameters PSP with an EDM wire 4 that is not prepared for this use.

[0082] As an example, for the wire "SA" mentioned above, it is possible to successfully use a variable functional offset in finishing using an optimized set of parameters, whereas for wire "SB" better finishing results are obtained with a fixed offset, i.e., with a standard set of processing parameters.

[0083] This is evident from the following measurement results herein: - by using the wire "SA" with the specific optimized processing parameters PSP for this wire "SA", the roughness Ra obtained in the direction of the wire is 0.16 microns and in the direction of the cut is 0.17 microns, such that the workpiece is considered conformal; - by using the wire "SB" with the same specific optimized processing parameters PSP of the wire "SA", the roughness Ra in the direction of the wire is 0.17 microns, whereas the roughness in the direction of the cut is 0.20 microns, such that the workpiece is considered non-conformal; - using the wire "SA" with standard processing parameters, the roughness Ra obtained in the direction of the wire is 0.19 microns and in the direction of the cut is 0.20 microns, such that the workpiece is considered conformal; - By using the wire "SB" with standard processing parameters, the roughness Ra obtained in the direction of the wire is 0.20 microns and in the direction of the cut is 0.21 microns, such that the workpiece is considered conformal.

[0084] In other words, if wire "SB" is used with the specific optimized processing parameters PSP of wire "SA", a significantly higher roughness Ra is obtained in the direction of cutting than in the direction of the wire, which is visible and which is considered non-conformal.

[0085] In contrast, if wire “SB” is used with standard processing parameters, the average roughness Ra is a little larger, but the roughness Ra in the cutting direction is close to the roughness Ra in the wire direction, such that the workpiece is visually considered conformal.

[0086] Thus, in cases where there is no certainty regarding the identity of the EDM wire 4, it is preferable to use a standard set of machining parameters PST.

[0087] To that end, according to an advantageous embodiment, the memory means 17b of the control circuit 17 further contains one or more sets of standard machining parameters PST, each determined after previous machining tests carried out with one and the same type of EDM machine 1 by using several types of EDM wire M and by obtaining a satisfactory average machining quality.

[0088] In this case, when at least one of the first and second enabling conditions is not fulfilled, the respective enabling sequence enables or induces machining with the EDM wire 4 by applying standard machining parameters PST, which are previously stored in a memory means 17b provided in the control circuit 17. In that way, the machining performed according to the standard machining parameters PST, automatically selected by the EDM machine 1, is not optimized, but is nevertheless optimal, i.e. deteriorated as little as possible.

[0089] In addition, taking into account that the use of specific optimized machining parameters PSP with an electric discharge machining wire 4, the type of which is different from the type normally provided, generally leads to a worse machining result than the machining result with the standard machining parameters PST, the invention, according to an advantageous embodiment, considers restricting or prohibiting the reading and copying of the specific optimized machining parameters PSP file stored in the storage means 17b of the electric discharge machining machine 1. To this end, the computer program P may contain a sequence for controlling access to the specific optimized machining parameters PSP, this access control sequence possibly requiring, for example, the entry of one or more secret codes. Cases in which a user tries to manually push through the use of a specific optimized machining parameter PSP in the hope of producing an optimized machining with an electric discharge machining wire 4 not prepared for its use, and then obtains a deteriorated and defective machining, are thus avoided.

[0090] The invention is not limited to the embodiments expressly described, but includes various modifications and generalizations of those embodiments that fall within the scope of the following claims.

Claims

1. 1. An electrical discharge machining method for an electrical discharge machining machine (1) using an electrical discharge machining wire (4) packaged on a reel (5) forming an assembly with an identification data carrier (11) in the form of an RFID radio tag data carrier, in which identification data (ME) relating to the electrical discharge machining wire (4) are stored in digital form at a specific location, (a) the electric discharge machining machine (1) receives from the identification data medium (11) read identification data (ML) representing the embedded identification data (ME) contained in the identification data medium (11); (b) the electric discharge machining method, in which the electric discharge machining machine (1) adapts its machining parameters by taking into account, inter alia, the read-out identification data (ML) emanating from the identification data medium (11) of the reel used for the machining, specific optimized machining parameters (PSP) are previously determined by machining tests carried out with an electric discharge machining wire of the same type as the type of the electric discharge machining wire (4) packed on the reel (5); The specific optimized machining parameters (PSP) and control functions (F) are stored in advance in a specific location in a storage means (17b) of the electric discharge machining machine (1); Standard machining parameters (PST) are determined in advance by machining tests carried out with various EDM wires; The standard machining parameters (PST) are stored in advance in a specific location in the storage means (17b) of the electric discharge machining machine (1); embedded control data (CE) are predetermined by the control function (F) to be linked to the embedded identification data (ME) of the electric discharge machining wire (4) and are stored at a specific location on the identification data medium (11), and, before step (b), The electric discharge machining machine (1) receives the read control data (CL) from the identification data medium (11), the electric discharge machine (1) checks to see whether the read identification data (ML) and the read control data (CL) are linked by the control function (F); said electric discharge machining machine (1) triggering or allowing said machining according to said specific optimized machining parameters (PSP) only if said read-out identification data (ML) and said read-out control data (CL) are linked by said control function (F); 10. The electric discharge machining method according to claim 9, wherein if the electric discharge machining machine (1) determines that the read-out identification data (ML) and the read-out control data (CL) are not linked by the control function (F), the electric discharge machining machine (1) triggers or allows the machining according to the standard machining parameters (PST).

2. determining the embedded control data (CE), the control function (F) is applied to the embedded identification data (ME) associated with the electric discharge machining wire (4); After receiving the read control data (CL), the electric discharge machining machine (1) applies the function (F) to the read identification data (ML) in order to deduce verification data (V) from the read identification data, and the electric discharge machining machine (1) compares the read control data (CL) received from the identification data medium (11) with the verification data (V), If the verification data (V) matches the read control data (CL), the electric discharge machine (1) considers that the read identification data (ML) and the read control data (CL) are linked by the control function (F).

2. The electric discharge machining method according to claim 1 .

3. determining the embedded control data (CE), the control function (F) is applied to the embedded identification data (ME) associated with the electric discharge machining wire (4); After receiving the read control data (CL), the electric discharge machine (1) calculates the inverse function (F) of the control function (F). －１ ) to the embedded control data (C) in order to deduce verification data (W) from the embedded control data, and the electric discharge machining machine (1) compares the read identification data (ML) received from the identification data medium (11) with the verification data (W), If the verification data (W) matches the read-out identification data (ML), the electric discharge machine (1) considers that the read-out identification data (ML) and the read-out control data (CL) are linked by the control function (F).

2. The electric discharge machining method according to claim 1 .

4. 4. The electric discharge machining method according to claim 1, wherein the control function (F) is an encryption private key encryption function (K).

5. An electric discharge machining machine (1) for the implementation of the method according to any one of claims 1 to 3, comprising: the electric discharge machining machine (1) forms a functional unit with a data reader device (13) capable of reading embedded identification data (ME) stored in a specific location in digital form in an identification data medium (11) in the form of an RFID radio tag, which forms an assembly with the reel (5) on which the wire (1) is packaged, and capable of transmitting the read identification data (ML) to the electric discharge machining machine (1), the data reader device (13) is further capable of reading the embedded control data (CE) held at a specific location in the identification data medium (11) of the reel (5) and transmitting the embedded control data to the electric discharge machining machine (1); The electric discharge machining machine (1) comprises a storage means (17b) in which specific optimized machining parameters (PSP) and control functions (F) are stored in specific locations, the electric discharge machining machine (1) comprises electric discharge machining wire recognition means comprising calculation means (17a) and a stored computer program (P) containing a recognition sequence capable of verifying whether the read-out identification data (ML) and the read-out control data (CL) are linked by the control function (F), the electric discharge machining machine (1) comprises control means (17) and a stored computer program (P) containing a control sequence capable of inducing or permitting the machining according to the specific optimized machining parameters (PSP) only if the read-out identification data (ML) and the read-out control data (CL) are linked by the control function (F), Electric discharge machining machine (1).

6. 4. A reel (5) of wire (1) for implementing the electric discharge machining method according to any one of claims 1 to 3, forming an assembly with an identification data medium (11) in the form of an RFID radio tag, the data of which can be read by a data reader device (13) forming a functional unit with the electric discharge machining machine (1), the identification data medium (11) carrying embedded identification data (ME) relating to the wire at a specific location, characterized in that the identification data medium (11) also carries embedded control data (CE) at a specific location, which is linked to the embedded identification data (ME) by a control function (F).

7. 7. A reel (5) of wire (1) for electrical discharge machining according to claim 6, characterized in that the control function (F) is an encrypting private key encryption function (K).

8. 7. A reel (5) of wire (1) for electrical discharge machining according to claim 6, characterized in that the identification data medium (11) is fixed onto a flange of the reel (5), or onto a pouch containing the reel (5), or is fixed or placed in a container containing the reel (5).

9. An electric discharge machining device (4) for the implementation of the method according to any one of claims 1 to 3, comprising: Electric discharge machining machine (1), EDM wire (4) packaged on a reel (5); an identification data medium (11) in the form of an RFID radio tag, forming an assembly with said reel (5) and accessible for reading the data it carries; embedded identification data (ME) of said wire, held in a specific location by said identification data medium (11); a data reader device (13) that forms a functional unit with the electric discharge machining machine (1) and that is capable of reading the embedded identification data (ME) carried by the identification data medium (11) of the reel (5) and of transmitting the read identification data (ML) to the electric discharge machining machine (1); In an electric discharge machining apparatus comprising: The embedded control data (CE) is furthermore held at a specific location on said identification data medium (11), the data reader device (13) is further capable of reading the embedded control data (CE) carried by the identification data medium (11) of the reel (5) and transmitting the embedded control data to the electric discharge machining machine (1); the electric discharge machining machine (1) comprises a storage means (17b) in which a control function (F) and specific optimized machining parameters (PSP) are stored in a specific location, the parameters being determined in advance by machining tests carried out with an electric discharge machining wire of the same type as the type of the electric discharge machining wire (4) packed on the reel (5); Standard machining parameters (PST) are determined in advance by machining tests carried out with various electric discharge machining wires and are stored in a specific location in the storage means (17b) of the electric discharge machining machine (1); the electric discharge machining machine (1) comprises electric discharge machining wire recognition means comprising calculation means (17a) and a stored computer program (P) containing a recognition sequence capable of verifying whether the read-out identification data (ML) and the read-out control data (CL) are linked by the control function (F), said electric discharge machining machine (1) comprising control means (17) and a stored computer program (P) containing a control sequence capable of inducing or permitting said machining according to said specific optimized machining parameters (PSP) only if said read-out identification data (ML) and said read-out control data (CL) are linked by said control function (F), If the read-out identification data (ML) and the read-out control data (CL) are not linked by the control function (F), the control sequence of the electric discharge machining machine (1) triggers or allows the machining according to the standard machining parameters (PST). An electric discharge machining device (4).

10. 9. The electric discharge machining apparatus according to claim 8, wherein the control function (F) is a private key encryption function (K) for encryption.

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