Process and device for machining a three-dimensional piece by electroerosive milling

Process to machine a three-dimensional piece (14) by milling with an electroerosion device, according to which

• an electrode-tool (31) of cylindrical shape whose diameter (2R) is small relative to the dimensions of the surfaces to be eroded, is driven in rotation,
• the three-dimensional relative movement (x, y, z) between the electrode-tool (31) and said piece (14) is controlled by means of a digital control unit (CN),
• there are recorded by computer means (MI) the shapes to be machined in the form of a superposition of virtual layers (33),
• a path of an electrode-tool (31) is simulated, such that this latter sweeps groove by groove, successively, each of the virtual layers, and the corresponding control signals are transmitted toward the digital control unit (CN) to carry out machining layerwise,
• by regulation means (MR), the longitudinal wear of the electrode-tool along its trajectory is simulated and corresponding compensation signals are transmitted to the digital control unit (CN) so as to compensate this longitudinal wear and to maintain the movement of the end of the electrode-tool parallel to said layers (33), characterized by the fact
• that there are provided several values for longitudinal wear of the electrode-tool (1) according to the mutual geometric configuration between the electrode-tool (31) and the nearby material of said piece (14),
• that values of compensation signals corresponding to each of these values are transmitted to the digital control unit (CN), and
• that said values take account on the one hand of the presence or absence of an opening in the nearby material located below the end of the electrode-tool facilitating the flow of the machining liquid, and on the other hand of the presence or absence of at least one or two walls of the nearby material located at a distance from the electrode-tool (31) which is smaller than a first predetermined distance.

Process to machine a three-dimensional piece (14) by milling with an electroerosion device, according to which

• an electrode-tool (31) of cylindrical shape whose diameter (2R) is small relative to the dimensions of the surfaces to be eroded, is driven in rotation,
• the three-dimensional relative movement (x, y, z) between the electrode-tool (31) and said piece (14) is controlled by means of a digital control unit (CN),
• there are recorded by computer means (MI) the shapes to be machined in the form of a superposition of virtual layers (33),
• a path of an electrode-tool (31) is simulated, such that this latter sweeps groove by groove, successively, each of the virtual layers, and the corresponding control signals are transmitted toward the digital control unit (CN) to carry out machining layerwise,
• by regulation means (MR), the longitudinal wear of the electrode-tool along its trajectory is simulated and corresponding compensation signals are transmitted to the digital control unit (CN) so as to compensate this longitudinal wear and to maintain the movement of the end of the electrode-tool parallel to said layers (33), characterized by the fact
• that there are provided several values for longitudinal wear of the electrode-tool (1) according to the mutual geometric configuration between the electrode-tool (31) and the nearby material of said piece (14),
• that values of compensation signals corresponding to each of these values are transmitted to the digital control unit (CN), and
• that there is fixed for each of the geometric configurations a value of longitudinal machining, by machining with pre-established values, by measuring the real longitudinal wear for the geometric configurations, and by replacing the pre-established values by measured values of longitudinal wear.

Device for machining by electroerosion to machine a piece (14) with three dimensions by layerwise electroerosion milling, comprising

• a member to drive in rotation an electrode-tool (31) of cylindrical shape whose diameter (R) is small relative to the dimensions of the surfaces to be eroded,
• a digital control unit (CN) adapted to control the relative three-dimensional movement between the electrode-tool (31) and the piece (14),
• a computer module (MI) permitting recording the shapes to be machined in the form of a superposition of virtual layers,
• a simulation module (MS) permitting simulating a path of the electrode-tool (31) such that this latter sweeps groove by groove, successively each of the virtual layers (33) and arranged to transmit corresponding control signals to the digital control unit (CN),
• a regulation module (MR) permitting simulating the longitudinal wear of the electrode-tool and its compensation along its path and to transmit toward the digital control unit (CN) compensation signals such as to regulate and compensate this longitudinal wear to maintain the movement of the end of the electrode-tool parallel to said layers, characterized by the fact
• that the regulation module (MR) is arranged to provide several values of longitudinal wear of the electrode-tool according to the mutual geometric configuration between the electrode-tool (31) and the nearby material of the piece (14) and to transmit compensation signals corresponding to each of these values to the digital control unit (CN) and
• that the regulation module (MR) is arranged to provide several values of longitudinal wear taking account of the geometric configuration of the flow between the electrode-tool (31) and the nearby material, of a machining liquid used for machining.

Device for machining by electroerosion to machine a piece (14) with three dimensions by layerwise electroerosion milling, comprising:

• a member to drive in rotation an electrode-tool (31) of cylindrical shape whose diameter (R) is small relative to the dimensions of the surfaces to be eroded,
• a digital control unit (CN) adapted to control the relative three-dimensional movement between the electrode-tool (31) and the piece (14),
• a computer module (MI) permitting recording the shapes to be machined in the form of a superposition of virtual layers,
• a simulation module (MS) permitting simulating a path of the electrode-tool (31) such that this latter sweeps groove by groove, successively each of the virtual layers (33) and arranged to transmit corresponding control signals to the digital control unit (CN),
• a regulation module (MR) permitting simulating the longitudinal wear of the electrode-tool and its compensation along its path and to transmit toward the digital control unit (CN) compensation signals such as to regulate and compensate this longitudinal wear to maintain the movement of the end of the electrode-tool parallel to said layers, characterized by the fact
• that the regulation module (MR) is arranged to provide several values of longitudinal wear of the electrode-tool according to the mutual geometric configuration between the electrode-tool (31) and the nearby material of the piece (14) and to transmit compensation signals corresponding to each of these values to the digital control unit (CN) and
• that the regulation module (MR) is arranged to begin machining with pre-established values of longitudinal wear, to measure the real longitudinal wear for each of the geometric configurations, and to replace the pre-established values by the measured values of longitudinal wear.

Device for machining by electroerosion to machine a piece (14) with three dimensions by layerwise electroerosion milling, comprising

• a member to drive in rotation an electrode-tool (31) of cylindrical shape whose diameter (R) is small relative to the dimensions of the surfaces to be eroded,
• a digital control unit (CN) adapted to control the relative three-dimensional movement between the electrode-tool (31) and the piece (14),
• a computer module (MI) permitting recording the shapes to be machined in the form of a superposition of virtual layers,
• a simulation module (MS) permitting simulating a path of the electrode-tool (31) such that this latter sweeps groove by groove, successively each of the virtual layers (33) and arranged to transmit corresponding control signals to the digital control unit (CN),
• a regulation module (MR) permitting simulating the longitudinal wear of the electrode-tool and its compensation along its path and to transmit toward the digital control unit (CN) compensation signals such as to regulate and compensate this longitudinal wear to maintain the movement of the end of the electrode-tool parallel to said layers, characterized by the fact
• that the regulation module (MR) is arranged to provide several values of longitudinal wear of the electrode-tool according to the mutual geometric configuration between the electrode-tool (31) and the nearby material of the piece (14) and to transmit compensation signals corresponding to each of these values to the digital control unit (CN) and
• that the regulation module (MR) is arranged so as to take account, during simulation of the values of longitudinal machining, on the one hand of the presence or absence of an opening in the nearby material located below the end of the electrode-tool (31) facilitating the flow of the machining liquid, and on the other hand of the presence or absence of at least one or two walls of the nearby material located at a distance from the electrode-tool (31) which is smaller than a first predetermined distance.