Electric heating – Metal heating – Cutting or disintegrating
Patent
1995-12-19
1998-06-23
Evans, Geoffrey S.
Electric heating
Metal heating
Cutting or disintegrating
B23H 102
Patent
active
057708312
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a power supply system for an electric discharge machine (EDM).
More specifically, the present invention relates to a power supply system for an electric discharge machine whereby during multiple electric discharge machining steps, multiple power supply circuits may be used simultaneously, or may be selected and used separately as appropriate to obtain a desired workpiece shape.
BACKGROUND OF THE INVENTION
Typically, power pulses are generated in a power supply unit, which is unavoidably positioned at some physical distance from a machining section which includes parts to support the workpiece and mechanical parts which move the tool electrode relative to the workpiece.
To obtain a product wherein the workpiece has a desired shape, machining must be performed with consideration of the accuracy of product shape and of the roughness of the machined surface of the product. Typically, if machining is done at a high discharge energy there will be a large volume of metal chips removed from the workpiece, and machining speed will be fast. On the other hand, when machining is performed at a high discharge energy, there is a tendency for the discharge to cause large craters to form on the work-piece surface and for the machined surface of the product to be rough.
Therefore, electric discharge machining is performed by separating a first machining stage, wherein the material is removed from the workpiece using rough machining, and a second machining stage, wherein machining is performed so as to improve the machined surface. For example, in a wire cut electric discharge machine, in which cutting of the workpiece by electric discharge is performed using a wire electrode as a tool, a "first cut" machining is first performed, wherein the workpiece is cut by a wire electrode at a high electric discharge energy to such a point that the cut pattern does not protrude into the workpiece beyond a desired outline. Next, a "second cut" is performed in which, following a specified path which is offset from the desired profile, the wire electrode and/or workpiece are moved in such a way that the wire electrode moves relative to the cut workpiece, and the machined surface is improved as the remaining material is removed using an electric discharge energy which is smaller than that used in the first cut. Generally, in order to obtain the desired machined surface roughness, multiple second cuts are performed. This is because the smaller the desired roughness of the machined surface and the finer the desired shape, the more difficult it is to obtain the desired machined surface roughness and desired shape in a single machining step. If a better accuracy of the machined surface roughness and shape is attained in the first cut stage, the number of subsequent machining steps can be reduced.
It is known that a wire electrode traveling between a pair of wire guides (upper and lower) under a specified applied tension and at a specified speed will slightly vibrate between the upper and lower wire guides. Because of this undesirable wire electrode vibration, the center portion between the upper surface and the bottom surface of the workpiece will be cut into unduly in the part of the workpiece which faces the wire electrode, resulting in an adverse effect on product shape accuracy. This adverse effect will be appear conspicuously at the final machining stage, in particular. By increasing the energy per unit time supplied to the gap, pressure on the wire electrode from the produced electric discharge can be used to reduce oscillation of the wire electrode. However, a small energy per power pulse is naturally sought, for example, in the above-mentioned second cut. When a smaller energy per pulse power pulse is supplied to the gap, the reduction of the amplitude of wire electrode vibration may be insufficient. In such cases, the peak current value of each power pulse is increased and its ON time shortened, while OFF time is also shortened, resulting in an increase in the power pulse re
REFERENCES:
patent: 2969482 (1961-01-01), Bruma et al.
patent: 4447695 (1984-05-01), Inoue
patent: 4798929 (1989-01-01), Itoh
patent: 5064984 (1991-11-01), Yamamoto et al.
patent: 5572003 (1996-11-01), Kaneko
Kaneko Yuji
Ueda Tadao
Evans Geoffrey S.
Sodick Co. Ltd.
LandOfFree
Power supply system for an electric discharge machine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Power supply system for an electric discharge machine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Power supply system for an electric discharge machine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1396302