Retrofitting Geared Servo Drive

Successful retrofit of Geared Servo drive for
Duplex Synchro-Fly Mill duty Sheeter

The Customer
The Customer is a leading and premier Paperboard manufacturer located in Vapi, Gujarat, producing Paperboard of High GSM range. In the finishing house, the unit has Duplex Synchro-fly Jagenberg Sheeters of 1960 origin, catering to its paperboard sheeting requirements.

About the Machine
These Sheeters were employing Double Drag Link Transmission and PIVs (the total machine was driven by a single DC drive of 75 HP capacity) for adjustment of cut lengths. The cut length adjustments were mechanical in nature and were time consuming. The
set-up time of machine was high and the cut length accuracies were lower.

Dynaspede was entrusted with the work of retrofitting Geared Servo Drives directly coupled to rotating cutter drums to achieve near ideal operational performance from one of the two machines.

Dynaspede's expertise was sought:

• To replace the Double Drag Link Transmission to each cutter section and drive each section with Near-Zero backlash-Geared Servo drive with optimum motion profile for the Synchro-fly Sheeters. To achieve Cut length accuracies in line with international standards i.e. within 1 mm with the limitations of other old mechanical transmissions
• To select the appropriate servo drive rating
• To cut length adjustments through Man-Machine Interface and set up time for different cut lengths to be conforming to within international standards by deployment of the “Servo drive System”
  
• The main DC motor which is speed-controlled by conventional means has to be driven by Speed feed-back-based Closed Loop type Digital DC Drive and the maximum line speed has to be below the design limits of the machine, depending on the least cut length automatically set on the MMI

Dynaspede Solution successfully deployed:

Two Geared AC Servo Motors (backlash of the gearboxes controlled within 5 arc min.) rated 37.5 HP are deployed for the two cutter sections driving the Bottom and top cutter drums of each section together. The original Double drag link transmission for the motion profile generation was removed and the Geared Servo motor outputs were directly coupled to bottom cutter drum shafts. Fully regenerative AC Servo motor drives are employed for controlling the cutter motion.

Dynaspede's complex motion profile is employed for each cutter section drive to achieve cutter operation as required on a Synchro-fly sheeter.

The operator through MMI provided on a operator-controlled station selects cut length.

Highlights of Dynaspede Synchro-fly sheeter Cut to Length systems

• Minimum maintenance is required AC Servo Motors
• Gearboxes used are backlash-controlled within 5 arc minutes mandatory for such precise positioning
• The Dynaspede system can handle high-speed Cut to length applications
• Dynaspede's unique Cut to Length Motion profile ensures optimum torque loading on Motors and other mechanical transmissions
• The motion profiles corrects online variations that occur during acceleration and deceleration of the machine automatically, ensuring cut length output from the machine in dynamic conditions
• The Dynaspede motion profile is designed to avoid crosscut Problems
• A large range of cut lengths are possible with the same accuracy of cutting, from 450 mm to 4500 mm
• The maximum line speed of the machine for a set cut length is automatically curtailed to the designed maximum line speeds of the machine thereby avoiding overloading and vibration problems
• System retrofit time is designed to be bare minimum to keep the machine downtime lowest for the retrofit