US 4,367,129 AGranted

Wire-electroerosion method and apparatus for forming a tapered contour in a workpiece

AssigneeInoue-Japax Research Incorporated

InventorKiyoshi Inoue

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Abstract

The workpiece is partially immersed in a first electroerosion-machining liquid so that the surface of the liquid is positioned at a predetermined height from the lower surface of the workpiece. A wire electrode is passed vertically through the workpiece to define a machining gap therebetween which extends across the entire thickness of the workpiece including an upper portion and a lower portion divided from each other by the liquid surface of the first electroerosion-machining liquid. A second electroerosion-machining liquid having a specific resistivity greater than that of the first is supplied from above the workpiece into the machining gap along the upper portion and then allowed to diffuse into the machining gap along the lower portion. Electroerosive material removal from the workpiece occurs along the upper portion uniformly at a first rate and along the lower portion at a varying second rate which is not less than the first rate and which increases as the distance from the liquid level is increased. By relatively displacing the wire electrode and the workpiece in the horizontal plane, a contour having a non-tapered and tapered sections stepped in the direction of thickness of the workpiece is thus generated in the workpiece.

Claims5

Dependent claims

A wire-electroerosion method of forming a workpiece with a contour having a non-tapered and tapered portions stepped in the direction of thickness of the workpiece, the method comprising the steps of:

disposing the workpiece in a worktank containing a first electroerosion-machining liquid so that said workpiece is partially immersed therein to a preselected height from the lower surface of the workpiece with the liquid surface level extending in a horizontal plane dividing said workpiece into a non-immersed upper portion and an immersed lower portion;
passing a continuous wire electrode vertically through said workpiece to define an elongate machining gap extending across said non-immersed upper and immersed lower portions, and axially displacing said wire electrode from a supply means to a collection means through said machining gap;
supplying from above said workpiece, a stream of a second electroerosion-machining liquid having a specific resistivity greater than that of said first liquid into said machining gap in said non-immersed upper portion and permitting said stream at least partially to diffuse into said machining gap in said immersed lower portion of the workpiece while applying a machining electric current between said wire electrode and said workpiece whereby electroerosive material removal from said workpiece occurs across said machining gap along said upper portion uniformly at a first rate and along said lower portion at a second rate which is not less than said first rate and which increases as the distance from said horizontal plane is increased;
maintaining said surface level of the liquid in said worktank substantially constant;
maintaining the specific resistivity of the liquid in said worktank substantially constant;
and
relatively displacing said wire electrode and said workpiece orthogonally to the axis of said wire electrode along a predetermined path.

4 more elements

A wire-electroerosion apparatus for forming a workpiece with a contour having a non-tapered and tapered portions stepped in the direction of thickness of the workpiece, the apparatus comprising:

a worktank for containing a first electroerosion-machining liquid and receiving the workpiece therein in such a manner that it is partially immersed in said liquid to a preselected height from the lower surface of the workpiece with the liquid surface level extending in a horizontal plane dividing the workpiece into a non-immersed portion and an immersed portion;
means for guiding a continuous wire electrode to pass vertically through said workpiece, thereby defining an elongate machining gap therebetween extending across said non-immersed upper and immersed lower portions;
means for axially displacing said wire electrode from a supply means to a collection means through said machining gap;
nozzle means disposed above said workpiece for supplying a stream of a second electroerosion-machining liquid having a specific resistivity greater than that of said first liquid into said machining gap in said non-immersed portion and permitting said stream at least partially to diffuse into said machining gap in said immersed portion of the workpiece;
power supply for applying a machining electric current between the wire electrode and said workpiece to produce electroerosive material removal from the workpiece across said elongate machining gap whereby the material removal occurs along said upper portion uniformly at a first rate and along said lower portion at a second rate which is not less than said first rate and increases as the distance from said horizontal plane is increased;
means for maintaining said surface level of the liquid in said worktank substantially constant;
means for the maintaining specific resistivity of the liquid in said worktank substantially constant;
and
machining feed drive means for relatively displacing said wire electrode and said workpiece orthogonally to the axis of said wire electrode along a predetermined path.

6 more elements

Dependencies are inferred from the claim text.