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US 4,366,359 AGranted
Wire cut electric discharge machining control method
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsTakeshi Yatomi, Yutaka Tanaka, Yoshio Ozaki
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AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsTakeshi Yatomi, Yutaka Tanaka, Yoshio Ozaki
Estimating the term…
A command average machining current It(n) corresponding to change of a workpiece thickness is given by the following equations: ##EQU1## wherein the reference Ia(n) designates an actual average machining current Ia(n) at the workpiece thickness (Tn); It(n) designates an average machining current of the control command; Fn designates an actual machining feed rate; Ia(o) designates an actual average machining current at the initiation of the machining; S(o) designates a machining width; and To designates a workpiece thickness. The command average machining current It(n) is compared with the actual average machining current and the electric condition is changed and controlled to approach the actual average machining current to the command average machining current It(n) thereby controlling the work groove width to be constant in an electric discharge machining of the workpiece with a wire electrode.
In an electric discharge machining control method where an electric discharge occurs at a minute gap between a wire electrode and a workpiece, having a work power source and a work liquid as a dielectric medium and controlling relative movement between said electrode and said workpiece, the improvement characterized by changing and controlling a machining current so as to control a work groove width to a command value, wherein the desired machining current at a specific point is determined by the thickness of said workpiece and the machining current at the beginning of the machining operation and the thickness of said workpiece at the specific point, the machining operation being controlled so that the actual machining current approaches the desired machining current thereby providing substantially the same work groove width at the beginning of the machining operation as the work groove width at said specific point.
In an electric discharge machining control method where an electric discharge occurs at a minute gap between a wire electrode and a workpiece, having a work power source and a work liquid is a dielectric medium and controlling relative movement between said electrode and said workpiece, the improvement characterized by changing and controlling a machining current so as to control a work groove width to a command value, wherein the region of said workpiece being machined changes thickness in a stepwise manner and the machining current is changed and controlled by changing and controlling the electric condition before the thickness of said region changes, thereby maintaining substantially the same work groove width before and after the thickness of said region changes.
In an electric discharge machining control method where an electric discharge occurs at a minute gap between a wire electrode and a workpiece, having a work power source and a work liquid as a dielectric medium and controlling relative movement between said electrode and said workpiece, the improvement characterized by changing and controlling a machining current so as to control a work groove width to a command value, wherein the controls of the machining current and the work groove width are performed by the following equations (1), (2) and (3):
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
Term ended 15 Sep 2000 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to an electric discharge machining using a wire cut type electrode to control a work groove width (a width of cut or a machined groove width) by controlling a work current so as to improve the accuracy of the work.
2. Description of the Prior Art
FIG. 1 is a schematic view of a conventional wire cut electric discharge machine;
FIG. 2 shows a configuration of a workpiece used for experiments with this invention;
FIGS. 3, 4 and 5 are graphs showing the results of machining the workpiece using the conventional method;
An embodiment regarding the control method of this invention will be described below.
FIG. 9 shows a schematic view of one embodiment of the electric discharge machine used for the method of the present invention.
In FIG. 9, the references (1) to (11) designates the same parts shown in FIG. 1; (14) designates a voltage generating circuit which receives the signal from the computer (7) and applies the voltage output to the input terminals (5To) of the comparator (5); (15) designates an electric condition control device which receives the signal from the computer (7) and applies the output to the work power source (4). The control method of the relative movement of wire electrode (1) and the workpiece shown in FIG. 9 is the same method of controlling the average voltage between electrodes (Eg) to be constant (Eg-Eo.apprxeq.0) as described with FIG. 1. Therefore, a description of this method is omitted. It should be noted that reference voltage (Eo) as in FIG. 1 is normally set by a circuit composed of hardware and when it is to be changed from outside, generally a knob for setting is used which is operated manually. Opposed to such a method, with the embodiment of this invention, before machining, reference voltage (Eo) is input in a digital signal to computer (7) manually with digital switches for setting and computer (7) issues commands from input data to voltage generating circuit (14) depending upon the input data, where reference voltage (Eo) is generated by the circuit (14).