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US 6,038,489 AGranted
Machine tools
AssigneeUnova U.K. Limited
InventorsJohn David Pickles, Selwyn Jonathan Griffiths
Life of this patent
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AssigneeUnova U.K. Limited
InventorsJohn David Pickles, Selwyn Jonathan Griffiths
Estimating the term…
In a machine tool, a component such as a grinding wheel acts on a workpiece to form the latter into a circularly asymmetric shape, for example, a crankpin. Movement of the grinding wheel is controlled by a control signal which is derived from theoretical relative positions and positional velocities of the grinding wheel relative to the workpiece. In the course of at least one revolution of the workpiece, the respective positions of the grinding wheel relative to the workpiece are measured for each of a succession of angular positions of the workpiece. The measured positions are compared with corresponding theoretical positions and data indicative of any differences are stored, and then used to modify the control signal during a subsequent revolution of the workpiece so as to compensate for any of said differences and thereby reduce the magnitude of any error which would have resulted from the measured positional differences.
A method of controlling a grinding machine so that a grinding wheel thereof removes material from a rotating workpiece so as to form the latter into a desired shape which is circularly asymmetric, the method comprising the steps of:
A method of controlling a grinding machine so that a grinding wheel thereof removes material from a rotating workpiece so as to form the latter into a desired shape which is circularly asymmetric, the method comprising the steps of:
A grinding machine for grinding a rotating workpiece into a shape which is circularly asymmetric with the axis of rotation of the workpiece, the machine comprising a grinding wheel for removing material from the workpiece, drive means for moving the wheel along a path laterally relative to the axis of rotation of the workpiece so as to follow the desired contour of the workpiece, sensor means for sensing the position and positional velocities of the wheel relative to the workpiece, and control means connected to the drive means and the sensor means and arranged to generate a control signal derived from data of both theoretical positions and theoretical positional velocities of the wheel for each revolution of the workpiece to cause said relative movement of the wheel to measure, in the course of one revolution of the workpiece, the respective relative positions of the wheel when the workpiece is in each of a succession of angular positions, to compare said measured positions with the corresponding theoretical positions, to store data indicative of any differences between measured and theoretical positions, and to modify the control signal during a subsequent revolution of the workpiece so as to compensate for said differences and thereby reduce the magnitude of any error which would have resulted from said measured positional differences.
Dependencies are inferred from the claim text.