摘要:
An apparatus and method are disclosed for controlling the motion of a machine system so as to cut individual lengths from a web having graphics on predetermined web positions and which allows the use of an inexpensive AC induction motor. An AC induction motor (42) has an output power shaft for imparting the motive force necessary to drive the machine system, such as a web feeding system. A sensor (29) is operatively coupled to the AC motor for determining the position of the motor during system operation. A controller (26) is operatively connected to the sensor and motor and forms a closed loop control circuit. The controller changes the feedback loop characteristics of the closed loop control circuit during a stop, hold or start condition of the motor. By adding an externally generated compensating signal to the input of the feedback loop, the controller also minimizes acceleration error. The controller also limits the value of a signal reaching the feedback loop of the control circuit to a given maximum value so as to eliminate any over-reaction of the system, while allowing a signal having less than a given threshold value to proceed unaffected to the feedback loop.
摘要:
An apparatus and method (10) for controlling the tension and stopping action of web material fed from a supply roll (S) is disclosed. A supply roll of web material is supported on a support assembly (14) . A brake (26) is operatively connected to the support assembly (14) for applying a braking force onto the support assembly to apply tension onto the withdrawn web material. The diameter of the supply roll is sensed (32) and a signal is generated to the power supply (30) of a brake proportional to the diameter of the supply roll to vary the applied braking force and maintain a constant tension on the web material during its withdrawal. A stopping signal is generated to the brake power supply during stopping operation of film withdrawal to increase the braking force supplied to the support assembly. The stopping signal is an additive combination of a first signal that is essentially proportional to the diameter of the supply roll and a second signal that is essentially constant.
摘要:
An apparatus and method are disclosed for controlling the motion of a machine system so as to cut individual lengths from a web having graphics on predetermined web positions and which allows the use of an inexpensive AC induction motor. An AC induction motor (42) has an output power shaft for imparting the motive force necessary to drive the machine system, such as a web feeding system. A sensor (29) is operatively coupled to the AC motor for determining the position of the motor during system operation. A controller (26) is operatively connected to the sensor and motor and forms a closed loop control circuit. The controller changes the feedback loop characteristics of the closed loop control circuit during a stop, hold or start condition of the motor. By adding an externally generated compensating signal to the input of the feedback loop, the controller also minimizes acceleration error. The controller also limits the value of a signal reaching the feedback loop of the control circuit to a given maximum value so as to eliminate any over-reaction of the system, while allowing a signal having less than a given threshold value to proceed unaffected to the feedback loop.