Electric heating – Metal heating – Cutting or disintegrating
Patent
1992-12-23
1994-07-05
Evans, Geoffrey S.
Electric heating
Metal heating
Cutting or disintegrating
219 6917, B23H 710
Patent
active
053269543
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an electric discharge machining process for finishing cutter plates by means of an electrode wire, wherein a respective cutter plate is rotated under program control about a workpiece axis and is adjusted rectilinearly with respect to the electrode wire along at least one of three axes of a rectangular coordinate system, among them one axis which is parallel to the workpiece axis.
The invention further relates to a machine for electric discharge machining of cutter plates, comprising axis, relative movements between the cutter plate and the electrode wire along the three axes of a rectangular coordinate system.
Cutter plates with the machining of which for purposes of making or sharpening them the invention is concerned are soldered or clamped, for example, to milling or lathe tools. They may be designed as reversible plates and thus have a plurality of cutting edges adapted to be moved into operating position one after the other. Milling cutters above all for working on plates, boards, or strips of wood or plastics often are furnished with cutting plates which have complicated contours and require considerable expenditure in terms of control and programming to be machined according to known methods and with known machines in order to make sure that the most favorable front clearance angles and cutting angles are observed at all the flanks and machining surfaces, respectively, adjacent the cutting edges of such cutter plates. Trade-offs often had to be made in dimensioning these angles in view of the high programming expenditure involved, and the cutting performance and service life of the cutter plates were affected unfavorably by them.
It is, therefore, the object of the invention to improve a process and a machine for electric discharge machining of cutter plates such that the most favorable angles, especially front clearance angles can be observed accurately and with but little programming and control expenditure even for complicated cutter plate contours.
As regards the process, this object is met, starting from a process of the kind specified initially, in that according to the invention the cutter plate is rotated in such manner about the workpiece axis, during the machining of a flank adjacent a cutting edge, that the point at which the electrode wire touches the cutting edge always lies on a tool axis which extends at right angles to the electrode wire and to two axes of the coordinate system.
In this context it is especially advantageous if the electrode wire is rotated about the tool axis during the machining of portions of the flank which are located adjacent portions of the cutting edge not in parallel with the workpiece axis.
The rotation about the tool axis makes it possible to keep the front clearance angle of a cutter plate constant, as measured in a plane at right angles to the workpiece axis, even if the cutting edge extends at different radial spacings from the workpiece axis. The provision of the tool axis at right angles to the workpiece axis and the circumstance of the workpiece axis passing through the cutting edge result in distortion-free machining even of lateral flanks whose front clearance angle is measured in a plane parallel to the workpiece plane.
Inasmuch as the object of the invention relates to a machine, it is met according to the invention, starting from a machine of the kind mentioned initially, in that the wire fixture is rotatable under program control about a tool axis which extends at right angles to the electrode wire and to two axes of the coordinate system.
The machine according to the invention conveniently is developed further in that the wire fixture is disposed on a rotary member which is rotatable about the tool axis and further carries a sensor for measuring contours and surfaces of the cutter plate.
An embodiment of the invention will be explained in greater detail below, with reference to diagrammatic drawings, in which:
FIG. 1 is an oblique view of a machine according to the invention for electric discharge machining of cutter p
REFERENCES:
patent: 4301349 (1981-11-01), Inoue
patent: 4490600 (1984-12-01), Rae
patent: 4673787 (1987-06-01), Inoue
patent: 4841126 (1989-06-01), Graeber
patent: 4851633 (1989-07-01), Buhler
patent: 4960971 (1990-10-01), Kawanabe
patent: 4983078 (1991-01-01), Unozawa
patent: 5014421 (1991-05-01), Swarden et al.
"Fein-Schneiderrodieren beliebiger Profile," Werkstatt und Betrieb, 117 (1984) vol. 4, p. 216.
Bailer Norbert
Lenard Peter
Evans Geoffrey S.
Vollmer Werke Maschinenfabrik GmbH
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