Numerical machine tool control system including means to digitally simulate a template follower

Claim 2

In a machine tool having a slide, drive means including an electric motor for moving said slide at a velocity proportional to the speed of said motor; means for generating a train of pulses each indicative of a predetermined increment of commanded motion of said slide, means for measuring the actual movement of said slide with the movement commanded by said pulses and deriving an indication of the position error therebetween, means for deriving a velocity indication of the slide, means for comparing said position error indication and said velocity indication, and means responsive to said comparing means for inhibiting said drive means if said position error indication is below a predetermined value with respect to said velocity indication and for accelerating said drive means if said position error indication is above a second predetermined relation with said velocity indication.

Claim 3

The invention of claim 1, wherein said drive means includes forward and reverse engageable clutches, a capacitor and a charging path therefor, means responsive to a first magnitude of the position error with respect to the velocity of the slide for energizing one of said clutches, means responsive to a second magnitude of the position error with respect to the velocity of the slide for enabling said capacitor-charging circuit, and means responsive to the charging of said capacitor for increasing the speed of said motor.

Claim 4

The invention of claim 2, further including means responsive to a minimum magnitude of said position error with respect to said velocity for disabling said clutches and establishing a discharge path for said capacitory.

Claim 5

The invention of claim 1, wherein said drive means includes forward and reverse engageable clutches, and means responsive to the position error reaching a predetermined magnitude with respect to said velocity for engaging one of said clutcHes.

Claim 6

In combination, a machine tool including a slide drive means for driving said slide, means for generating a train of command pulses where each pulse represents an increment of movement of said slide, means providing a signal proportional to the velocity of said slide, means for generating a constant frequency pulse train, first means for counting said constant frequency pulses, second means for algebraically counting said constant frequency pulses and said command pulses, a phase resolver having rotor windings, means for converting the overflow pulses of said first counting means to a sinusoidal wave and applying said sinusoidal wave to the rotor windings of said phase resolver, the rotor of said phase resolver being angularly displaced by motion of said slide, means for converting the stator waveform of said phase resolver to a rectangular waveform, means for comparing the phase relation of the overflow waveform from said first means for counting with the rectangular waveform to determine the position error of said slide with respect to said velocity signal, and means responsive to a first relationship of said waveforms relative to the magnitude of the velocity signal for inhibiting said drive means and to another relationship of said waveforms relative to the magnitude of the velocity signal for accelerating said drive means.

Claim 7

In combination, a machine tool including a slide drive means for driving said slide, means for generating a train of command pulses where each pulse represents an increment of movement of said slide, means providing a signal proportional to the velocity of said slide, means for generating a constant frequency pulse train, first means for counting said constant frequency pulses, second means for algebraically counting said constant frequency pulses and said command pulses, a phase resolver having rotor windings, means for converting the overflow pulses of said first counting means to a sinusoidal wave and applying said sinusoidal wave to the rotor windings of said phase resolver, the rotor of said phase resolver being angularly displaced by motion of said slide, means for converting the stator waveform of said phase resolver to a rectangular waveform, means for comparing the phase relation of the overflow waveform from said first means for counting with the rectangular waveform to determine the position error of said slide with respect to said velocity signal, and means responsive to a first relationship of said waveforms relative to the magnitude of the velocity signal for inhibiting said drive means and to another relationship of said waveforms relative to the magnitude of the velocity signal for accelerating said drive means.

Claim 8

The invention of claim 5, further including means for deriving a voltage signal proportional to the position error indicated by said phase relationship, and means for comparing said voltage signal to said velocity signal to determine the position error with respect to the velocity signal.

Claim 9

The invention of claim 5, wherein said drive means for said slide comprises a motor and forward and reverse clutches, means responsive to said comparison means for disengaging said clutches when said position error is below a predetermined relation with said velocity signal and engaging one of said clutches when said position error is above said predetermined relation with said velocity signal.

Claim 10

The invention of claim 7, further including a capacitor, means providing charging and discharging circuit paths for said capacitor, means responsive to said position error being below said predetermined relation for discharging said capacitor, means responsive to said second predetermined relation for charging said capacitor and accelerating said motor with the voltage increase on said capacitor.

Claim 11

The invention of claim 8, further including means for interrupting charging of said capacitor without discharging said capacitor when the relationship of said position error falls below said second predetermined relationship but not below said predetermined relationship.

Claim 12

In combination, a machine tool having a slide, drive means for moving said slide along a predetermined path, means for generating a train of pulses each indicative of an increment of movement of said slide, means for measuring the actual movement of said slide, means responsive to the pulses of said train and said measuring means for providing in indication of the position lag of the slide behind its commanded position, means for deriving a voltage proportional to the velocity of the slide, and means responsive to a first predetermined relation of the position lag indication and the proportional voltage for inhibiting said drive means if said position error indication is below a predetermined value with respect to said velocity indication and for accelerating said drive means if said position error indication is above a second predetermined relation with said velocity indication.

Claim 13

In combination, a machine tool having a slide, drive means for moving said slide along a predetermined path, means for generating a train of pulses each indicative of an increment of movement of said slide, means for measuring the actual movement of said slide, means responsive to the pulses of said train and said measuring means for providing in indication of the position lag of the slide behind its commanded position, means for deriving a voltage proportional to the velocity of the slide, and means responsive to a first predetermined relation of the position lag indication and the proportional voltage for inhibiting said drive means if said position error indication is below a predetermined value with respect to said velocity indication and for accelerating said drive means if said position error indication is above a second predetermined relation with said velocity indication.

Claim 14

The invention of claim 10, wherein said drive means is disconnected during a first relationship of said voltage signals, said drive means is operative during a second relation of said voltage signals at substantially constant velocity, and said drive means is operative and the velocity thereof is increased during a third relation of said voltage signals.

Claim 15

The invention of claim 10, whereiN said drive means includes forward and reverse engageable clutches, a capacitor and a charging path therefor, means responsive to a first magnitude of the position error with respect to the velocity of the slide for energizing one of said clutches, means responsive to a second magnitude of the position error with respect to the velocity of the slide for enabling said capacitor-charging circuit, and means responsive to the charging of said capacitor for increasing the speed of said motor.

Claim 16

The invention of claim 12, further including means responsive to a minimum magnitude of said position error with respect to said velocity for disabling said clutches and establishing a discharge path for said capacitor.

Claim 17

For use in combination with a machine tool of the type having a cutting tool, drive means for relatively moving machine parts along predetermined axes, a tracer arm adapted to contact a template and to control the operation of said drive means, said tracer arm having an electrical contact thereon adapted to open and close contacts to deenergize and energize said drive means, said tracer arm being so positioned that upon predetermined deflection thereof it makes or breaks an electrical contact with one or more of said contacts; means for determining the position lag of each of said machine parts with respect to a commanded position, means for deriving a signal proportional to the velocity of each machine part, means for comparing the position lags with respective one of said velocity signals to derive a simulation of opening and closing the contacts, and means responsive to said simulations for controlling the operation of said drive means.

Claim 18

For use in combination with a machine tool of the type having a cutting tool, drive means for relatively moving machine parts along predetermined axes, a tracer arm adapted to contact a template and to control the operation of said drive means, said tracer arm having an electrical contact thereon adapted to open and close contacts to deenergize and energize said drive means, said tracer arm being so positioned that upon predetermined deflection thereof it makes or breaks an electrical contact with one or more of said contacts; means for determining the position lag of each of said machine parts with respect to a commanded position, means for deriving a signal proportional to the velocity of each machine part, means for comparing the position lags with respective one of said velocity signals to derive a simulation of opening and closing the contacts, and means responsive to said simulations for controlling the operation of said drive means.