Machine tool servo system including feed-rate control

Claim 2

In an automatic machine tool control system for producing relative movement between a workpiece and a machining tool, an analog servosystem for effecting the relative movement in response to a command signal, the servosystem being of the proportional position loop type wherein the instantaneous comparison of a feedback position signal and a command position signal provides an error signal for effecting the rate of relative movement, the command signal being a ramp signal having position information varying at a predetermined rate thereby to effect relative movement between the workpiece and the machining tool at a corresponding predetermined rate, and means operative upon discrete electrical quantities for applying a command position signal to the servosystem, comprising a pulse generator providing constant voltage pulses, a resistive divider network for altering the amplitude of the pulses in proportion to the desired rate of relative movement, and an integrator circuit for accumulating such pulses to provide a changing signal having a slope indicative of the rate of relative movement, said changing signal being a ramp voltage output.

Claim 3

A control system for a machine tool of the automatic type wherein a slide is moved at a rate related to rotation of a spindle of the machine tool for performing the machining operation comprising retract means for providing a signal for causing movement of the tool slide in a reverse direction at a rapid traverse rate, set position means for providing a signal indicative of the extent of forward movement of the tool slide at a rapid traverse rate, rate means for providing a signal indicative of the rate of forward movement of the tool slide during the machining operation, feedback means for providing a signal representative of the instantaneous position of the tool slide, means for combining the signals of the set position means and the feedback means to provide a difference signal, servodrive means responsive to the difference signal for moving the tool slide, means for comparing the signals of the set position means and the feedback means and for providing a comparison signal when equality is attained, means responsive to the comparison signal of the comparing means for combining the signals of the rate means and the feedback means to provide a second difference signal for application to said servodrive means for further movement of the tool slide, and means for sensing completed movement of the tool slide and for combining the signals of the retract means and the feedback means to provide a third difference signal for application to said servodrive means for reverse movement of the tool slide to a fully retracted position.

Claim 4

A control system for a machine tool of the automatic type wherein a slide is moved at a rate related to rotation of a spindle of the machine tool for performing the machining operation comprising retract means for providing a signal for causing movement of the tool slide in a reverse direction at a rapid traverse rate, set position means for providing a signal indicative of the extent of forward movement of the tool slide at a rapid traverse rate, rate means for providing a signal indicative of the rate of forward movement of the tool slide during the machining operation, feedback means for providing a signal representative of the instantaneous position of the tool slide, means for combining the signals of the set position means and the feedback means to provide a difference signal, servodrive means responsive to the difference signal for moving the tool slide, means for comparing the signals of the set position means and the feedback means and for providing a comparison signal when equality is attained, means responsive to the comparison signal of the comparing means for combining the signals of the rate means and the feedback means to provide a second difference signal for application to said servodrive means for further movement of the tool slide, and means for sensing completed movement of the tool slide and for combining the signals of the retract means and the feedback means to provide a third difference signal for application to said servodrive means for reverse movement of the tool slide to a fully retracted position.

Claim 5

A control system as set forth in claim 2 further including a dwell timer operative in response to the completed movement sensing means for delaying the combining of the signals of the retract means and the feedback means.

Claim 6

A control system as set forth in claim 2 wherein the means for combining the signals of the rate means and the feedback means further combines the signal of the set position means to provide a second difference signal.

Claim 7

In an automatic machine tool control system for producing relative movement between a workpiece gripped in a rotatable spindle of tHe machine tool and a machining tool, a servosystem for effecting the relative movement in response to a command signal, said servosystem being of the analog proportional position loop type wherein the instantaneous comparison of a feedback position signal and a command position signal provides an error signal for effecting the rate of relative movement, the feedback and command signals being varying continuous signals indicative instantaneously of the actual and desired relative positions, respectively, the signals being electrical quantities having amplitudes proportional to such positions, and means for applying a command position signal to said servosystem, the command signal being a ramp function having a slope indicative of a predetermined rate of relative movement and containing position information varying at a predetermined rate, said means comprising a generator driven by the spindle for providing a changing voltage output proportional to the speed of spindle rotation, means for varying the output of said generator in proportion to the desired rate of relative movement, and accumulator means responsive to the output of said generator for providing a changing signal having a slope indicative of the rate of relative movement.

Claim 8

In an automatic machine tool control system for producing relative movement between a workpiece gripped in a rotatable spindle of tHe machine tool and a machining tool, a servosystem for effecting the relative movement in response to a command signal, said servosystem being of the analog proportional position loop type wherein the instantaneous comparison of a feedback position signal and a command position signal provides an error signal for effecting the rate of relative movement, the feedback and command signals being varying continuous signals indicative instantaneously of the actual and desired relative positions, respectively, the signals being electrical quantities having amplitudes proportional to such positions, and means for applying a command position signal to said servosystem, the command signal being a ramp function having a slope indicative of a predetermined rate of relative movement and containing position information varying at a predetermined rate, said means comprising a generator driven by the spindle for providing a changing voltage output proportional to the speed of spindle rotation, means for varying the output of said generator in proportion to the desired rate of relative movement, and accumulator means responsive to the output of said generator for providing a changing signal having a slope indicative of the rate of relative movement.

Claim 9

An automatic machine tool control system for effecting relative movement between a workpiece supported in a rotatable spindle of the machine tool and a machining tool comprising a closed loop position servocontrol for effecting the relative movement in response to position command signals, a first voltage generator for providing a first command signal to said servocontrol to effect relative movement between the workpiece and the machining tool from a retracted position to a relatively adjacent position, means connected to the spindle for generating an output representative of the rotational velocity of the spindle, a ramp voltage generator adapted to receive the output of said spindle generating means to provide a ramp voltage having a slope directly related to the spindle velocity, the ramp voltage being a second command signal to effect relative movement at a preselected rate during contact between the workpiece and the machining tool, a third voltage generator for providing a third command signal to effect relative movement in a reverse direction to a retracted position, means for sensing relative positions of the workpiece and machining tool for providing discrete signals representative thereof, switching means responsive to said sensing means for applying said command signals to said servocontrol, said switching means including means for combining two of said command signals for simultaneous application to said servocontrol to effect relative movement as a function of the combination of command signals, and time delay means responsive to the signals of said sensing means for interrupting said switching means for a predetermined interval.

Claim 10

An automatic machine tool control system for effecting relative movement between a workpiece supported in a rotatable spindle of the machine tool and a machining tool comprising a closed loop position servocontrol for effecting the relative movement in response to position command signals, a first voltage generator for providing a first command signal to said servocontrol to effect relative movement between the workpiece and the machining tool from a retracted position to a relatively adjacent position, means connected to the spindle for generating an output representative of the rotational velocity of the spindle, a ramp voltage generator adapted to receive the output of said spindle generating means to provide a ramp voltage having a slope directly related to the spindle velocity, the ramp voltage being a second command signal to effect relative movement at a preselected rate during contact between the workpiece and the machining tool, a third voltage generator for providing a third command signal to effect relative movement in a reverse direction to a retracted position, means for sensing relative positions of the workpiece and machining tool for providing discrete signals representative thereof, switching means responsive to said sensing means for applying said command signals to said servocontrol, said switching means including means for combining two of said command signals for simultaneous application to said servocontrol to effect relative movement as a function of the combination of command signals, and time delay means responsive to the signals of said sensing means for interrupting said switching means for a predetermined interval.