Method of and apparatus for determining relative position of a tool member to a workpiece in a machine tool
AssigneeInoue-Japax Research Incorporated
InventorKiyoshi Inoue
Life of this patent
Estimating the term…
Abstract
A technique for accurately determining the size of a machining gap and a specific resistivity thereof in a machine tool, especially an electroerosion machine tool (e.g. EDM machine), measures the electrical resistance between a tool member and a workpiece in a given relative position to give a first measurement value. The tool member and the workpiece are then relatively displaced by a known distance from the given relative position to establish a shifted relative position and the electrical resistance therebetween is measured to give a second measurement value. The calculation from the first and second measurement values yields one of the given and shifted relative position and the specific resistivity of the gap.
Claims22
A method of determining relative position of a tool to a workpiece in a machine tool, comprising:
- (a) measuring the electrical resistance between said tool member and said workpiece in a given relative position to give a first measurement value;
- (b) relatively displacing said tool member and said workpiece by a known distance whereby to establish a shifted relative position between said tool member and said workpiece;
- (c) measuring the electrical resistance between said tool member and said workpiece in said shifted relative position to give a second measurement value;
- and
- (d) calculating at least one of said given and shifted relative positions between said tool member and said workpiece from said first and second measurement values and said known distance.
A machine tool comprising in combination:
- a tool member for machining a workpiece in a given machining operation;
- means for interrupting said machining operation with said machine tool;
- drive means for relatively displacing said tool member and said workpiece to hold them in a given relative position when said given machining operation is interrupted by said interrupting means and subsequently to place them in a relative position shifted by a known distance from said given relative position during a period of the said interruption of the machining operation,
- sensing means for measuring the electrical resistance between said tool member and said workpiece in said given relative position and subsequently the electrical resistance between said tool member and workpiece in said shifted relative position to give a first and second measurement values, respectively;
- and
- computing means for calculating at least one of said given and shifted relative positions from said first and second measurement values and said known distance.
Dependencies are inferred from the claim text.