Cut-to-length

Geared Servo Drive System replacing Electromagnetic Clutch-Brake
Combination in CSS Lines of a premier Paper Mill

The Client

The client is a premier Paper and Pulp manufacturer in Orissa bordering the state of Andhra Pradesh in India, producing printing and writing Paper. The unit requires in its finishing house two CSS Lines of Wills origin for A4, A3 and Copier sheets.

Solution sought:

In the wrapping machines, the requirement was to cut the wrapper laminate (BOPP–Paper or Polyester-Paper) to a desired size within tolerable limits of +/- 1 mm without cumulative errors and convey the cut laminate to the precise position of the folding table for Folding, Gluing and Packet formation. The machines were 1960 and 1982 models. Originally the machines were supplied with Electromagnetic Clutch-Brake combinations to achieve this operation of cutting and conveyance of cut sheets to folding table. But due to inherent weaknesses of Clutch-Brake combinations and mechanical transmissions, the machines could not deliver accuracy in cut length and precise positioning of the cut sheets on the folding table, which resulted in imperfect packet formation. They took very long to perform the task time due to bad mechanical adjustment. Also, they were not capable of executing Registration mark sensing and cutting.

Solution employed:

Dynaspede, with its inherent strength gained over three decades in application engineering, design and development, developed a system revolving around a unique Near Zero Backlash Geared AC Servo Drive system and Particle brake-based unwind tension control system, and successfully retrofitted the same on the two wrapping machines of CSS Lines with strong technical support from the client. Two Servo drive systems were deployed in a machine, one for Indexing (Wrapper laminate in feed) and the other for vacuum feed (wrapper laminate out feed up to folding table)

Advantages of the System

• Reduction in Wills Cutter production wastage and avoidance of Pemco machines rewrapping Operations
• Reduction in Wrapper Laminate wastage
• Accuracy of Cut length pegged at +/- 1mm
• Assured consistency of machine operation.
• Reduced time and ease of wrapper laminate length change-over through Man-Machine Interface
• Elimination of cumulative errors throughout process operation
• Facility to add ink jet printer in the machine for printing Batch no., Manufacturing date, MRP etc
• Avoidance of subsequent label sticking operation, making the packets ready to dispatch directly from the machine
• Reduction in demand for manual intervention for obtaining optimum performance from the Machine
• System requirement of Near Zero Routine Maintenance for optimum performance

System's Special Features

1. State-of-art AC Servo motor of very low moment of inertia with near-zero backlash (controlled within 5 arc minute at the output) planetary gear transmission
2. AC Servo motor flange mounted on Gearbox for compactness of design and retrofitting ease
3. Systems flexibility to accept wide Cut length range (for A3, A4 and Copier sheets) through Man-Machine interface
4. Cut Length Mode/ Registration mark Mode (by way of color mark sensor sensing Registration mark)
   possible for pre-printed wrapper laminate cutting and positioning operation
5. Accurate Position controls
6. High resolution built in Pulse encoder for accurate position controls.
7. Dynaspede Particle brake at the wrapper laminate unwind roll for accurate control of torque based on accumulator roll assembly position sensing
8. Rugged sensor for Position sensing of accumulator roll assembly.