Method and apparatus for preventing machine damage
View Patent ↗In a web-fed rotary printing machine having a plurality of cylinders rolling on one another, each cylinder is driven by a respective drive motor, and a control device synchronizes the motors to run at the same speed. The control device has stored therein a control program which can be activated in the event of a web break. The control program has an emergency stop ramp which brakes the motors to a standstill by jerked stop, preferably within five revolutions, the program driving the motors along the stop ramp in the event of a web break.
1. Method of preventing machine damage in the event of a web break in a web-fed rotary printing machine comprising a plurality of cylinders which, in a print-on position, roll one on another, said printing machine further comprising a plurality of drive motors for driving said cylinders, wherein each said cylinder is driven by a respective said drive motor, said method comprising
synchronizing the motors so that they are all driven at the same speed,
detecting when a web break occurs, and
braking said drive motors to a standstill within five revolutions by reversing the effective direction of torque produced by the motors when a web break occurs.
2. Method according to claim 1 wherein said drive motors are braked to a standstill within two revolutions when a web break occurs.
3. Method as in claim 2 wherein said drive motors are braked to a standstill within one revolution when a web break occurs.
4. Method as in claim 1 wherein, during braking, said cylinders remain in the print-on position.
5. The method of claim 1 wherein said motors are induction motors, said motors being braked by overloading said motors.
6. Method according to claim 1 further comprising:
providing a control program having therein an emergency stop ramp which brakes said motors to a standstill within five revolutions when a web break is detected, and
activating said control program when said web break is detected.
7. Apparatus for preventing machine damage in the event of a web break in a web-fed rotary printing machine having a plurality of cylinders which, in a print-on position, roll one on another, said printing machine further comprising a plurality of drive motors for driving said cylinders, wherein each said cylinder is driven by a respective said drive motor, said apparatus comprising
a control device for synchronizing the motors so that they are all driven at the same speed, said control device having stored therein a control program which can be activated in the event of a web break, said control program having therein an emergency stop ramp which brakes said motors to a standstill within five revolutions, said program driving said motors along said stop ramp in the event of a web break.
8. Apparatus as in claim 7 wherein said each said cylinder is a built up cylinder having a hollow center part.
9. Apparatus as in claim 7 wherein each said drive motor is an induction motor.
10. Apparatus as in claim 7 wherein said control program drives motors along said stop ramp by operating said motors in the overload range.
11. Apparatus as in claim 7 wherein said control program brakes said motors by reversing the effective direction of torque produced by the motors.
12. Apparatus as in claim 7 wherein said control program brakes all of said motors to a standstill simultaneously.
13. Apparatus as in claim 7 wherein said control program brakes said motors to a standstill within two revolutions.
14. Apparatus as in claim 13 wherein said control program brakes said motors to a standstill within one revolution.
15. Method as in claim 1 comprising braking all of said drive motors to a standstill simultaneously when a web break occurs.