Claims
- 1. In a web handling system in which increments of a continuous web are cyclically fed by a pair of rolls from a web supply through a process station at which an operation is performed on the web, said system further including means between said supply and said pair of rolls for accumulating a loop of web under predetermined tension, means for controlling operation of said rolls comprising,
- an electric motor directly coupled to said rolls whereby rotation of said motor always causes corresponding rotation of said rolls,
- pulse generating means coupled to said motor for producing a train of pulses representative of the extent and direction of rotation of said motor,
- bi-directional pulse counter means capable of being manually preset to a predetermined count corresponding to a desired length of the increment of web to be fed through said process station in each cycle of operation,
- means coupling the output of said pulse generating means to said counter to cause said counter to count up or down depending upon the direction of rotation of said motor, operation of said motor to move said web from said supply through said process station causing said counter to count down towards a zero count from said predetermined count,
- sensing means operable in response to the accumulation of a loop of web of predetermined length at least as great as said increment,
- voltage generating means responsive to operation of said sensing means to initiate rotation of said motor, said voltage generating means including
- first circuit means for generating a voltage pulse of a polarity to cause said motor to rotate in the direction to withdraw the web from said process station towards said supply,
- second circuit means actuated upon termination of said voltage pulse for generating a unidirectional voltage of a polarity to cause said motor to rotate in the direction to move the web from said supply to said process station,
- means coupling said voltage pulse and said unidirectional voltage successively in the order named to said motor to cause corresponding rotation thereof,
- and means operative when the number of pulses produced by said pulse generating means in response to rotation of said motor in the direction to move the web from said supply to said process station equals a total count preset in said counter, to stop rotation of said motor.
- 2. The web handling system of claim 1 wherein the total count preset in said counter comprises a predetermined count manually preset in said counter plus an additional count corresponding to pulses generated by said pulse generating means upon rotation of said electric motor in a direction to withdraw the web from said process station towards said supply in response to the voltage pulse generated by said first circuit means.
- 3. The apparatus of claim 1 further comprising
- digital-to-analog converter for converting pulses indicative of the current count in said counter to an analog voltage,
- means providing a separate output pulse from said counter indicative of said counter reaching a fixed count above zero and smaller than said preset predetermined count,
- and third circuit means responsive to said counter output pulse to terminate said unidirectional voltage and couple the analog voltage from said digital-to-analog converter to said motor, whereby said motor decelerates to a stop at the zero count at a rate determined by the rate of decrease of the count in said counter.
- 4. The apparatus of claim 3 wherein the unidirectional voltage generated by said second circuit means includes a first portion of linearly increasing amplitude for causing linear acceleration of said motor, followed by a constant amplitude portion for causing said motor to rotate at constant speed.
- 5. The apparatus of claim 3 wherein said process station is rendered operative in response to said fixed count output pulse from said counter.
- 6. In a web handling system in which increments of a continuous web are cyclically fed by a pair of rolls from a web supply through a process station at which an operation is performed on the web, means for controlling operation of said rolls comprising,
- an electric motor directly coupled to said rolls whereby rotation of said motor always causes corresponding rotation of said rolls,
- pulse generating means coupled to said motor for producing a train of pulses representative of the rotation of said motor,
- pulse counter means capable of being manually preset to a predetermined count corresponding to a desired length of the increment of web to be fed through said process station in each cycle of operation,
- means coupling the output of said pulse generating means to said counter to cause said counter to change its count relative to a preset count upon rotation of said motor,
- first circuit means for initiating rotation of said motor during each cycle and causing it to operate said rolls to move said web through said process station, and
- second circuit means responsive to said counter reaching a preselected pulse count smaller than said predetermined count simultaneously to render said first circuit means ineffective to cause rotation of said motor and to cause further rotation of said motor in response to the magnitude of the pulse count in said counter, whereby rotation of said motor slows as the number of pulses produced by said pulse generating means approaches the predetermined count preset in said counter and stops when the number of pulses produced by said pulse generating means equals the predetermined count preset in said counter.
- 7. The web handling system of claim 6 further comprising,
- means responsive to said counter reaching said preselected pulse count for activating said process station to operate on said web when said desired length increment of web has been fed through said process station in each cycle of operation.
- 8. The web handling system of claim 6 further comprising,
- means between said web supply and said rolls for maintaining the web supplied to said rolls under predetermined tension.
- 9. The web handling system of claim 6 wherein said first circuit means includes
- means operative at the beginning of each cycle to rotate said motor for a brief interval in a direction opposite to that for moving said web from said supply through said process station, whereby said web is first withdrawn from said process station and then fed through said process station by said rolls.
- 10. In a web handling system in which increments of a continuous web are cyclically fed by a pair of rolls from a web supply through a process station at which an operation is performed on the web, web drive means comprising,
- an electric motor directly coupled to said rolls whereby rotation of said motor always causes corresponding rotation of said rolls,
- signal generating means coupled to said motor for producing an electrical signal representative of the rotation of said motor,
- circuit means coupled to said motor for causing rotation thereof in accordance with voltages applied thereto,
- first voltage generating means for producing and applying to said circuit means a voltage for initiating operation of said motor and causing it to feed said web from said supply to said processing station at speeds dependent upon the magnitude of said voltage, the magnitudes and duration of the voltage produced by said first voltage generating means being controllable independently of the operation of said motor,
- and second voltage generating means responsive to the electrical signal produced by said signal generating means for producing and applying to said circuit means a voltage for reducing the speed of operation of said motor and terminating feeding of said web.
- 11. The apparatus of claim 10 wherein the voltage outputs of said first and second voltage generating means are applied seriatum to said circuit means.
- 12. The apparatus of claim 10 wherein said first voltage generating means is controlled to produce a voltage output having a first portion linearly increasing in magnitude to a predetermined level, and a second portion having a magnitude constant at said level.
- 13. The apparatus of claim 10 wherein said second voltage generating means responds to the electrical signal from said signal generating means to produce a voltage output decreasing hyperbolically to zero.
BACKGROUND OF THE INVENTION
This application is a continuation-in-part of application Ser. No. 382,319, filed July 25, 1973 now abandoned.
US Referenced Citations (5)
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
382319 |
Jul 1973 |
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