Paper Sheeters and Drive technologies

1. Four bar Linkage Mechanism in Papermaking and its
replacement Direct Servo drive technology in Roll to Sheeting
lines in a Paper Mill – Converting House
By Muralidhar Ekambaram
CEO, Adeptus Servo- Mechatronics Private Limited

2. “Certainly when I thought of the hetero structure laser, I did not intend to
invent CD Players. I could not have anticipated the tremendous impact of
fiber optic communications. The person who come up with applications
thinks differently than the scientist who lays the foundation” – Herbert
Kroemer, Nobel Laureate
The above validates the importance of Application Engineering in any
field of science

3. Few of the Old technologies Deployed & Gainfully employed:
NEVER EVER AN IDEA/ LEARNING/ CONCEPT/ DEVELOPMENT IS LOST - ALWAYS PRESENT/
REIMPLEMENTED/ IMPROVED IN SOME FORM
EXAMPLES IN TECHNOLOIGES
- ARCHIMEDES SCREW TURBINE – ENERGY GENERATION-287BC TO 212BC
- SWITCHED RELUCTANCE MOTORS – HIGH SPEED LOW POWER - MOTIVE APPLICATIONS –
W H Taylor – 1838
- PLANETARY GEAR TRANSMISSIONS – HIGHER EFFEICIENCIES & COMPACTNESS –
Leonardo Da Vinci – 1490
- PLANETARY SCREWS – ROTARY TO LINEAR MOTION CONVERTERS
- RADIO FREQUENCY COMMUNICATION – MODEMS FOR DATA COMMUNICATION – Early
20th Century
- - Grashof Criterion in Paper Cutters/ Sheeters – Early/ Middle 20th century

4. Paper cutters of Periods Pre Grashof Criterion employed
Rotary/Stationary Bed Knife
1) Top Knife rotates, Bottom knife stationary with Paper flowing in
Between
2) Performance - Trailing cut edge with burs for high GSM/
High Caliper papers
3) Performance – Parallelogram cuts for different cut lengths
Requiring rotating cutter angle adjustments in machine direction
4) Slow speed Machines

5. Mechanical Cutter Drive design for single rotating knife version

6. Dual rotating cutters
Conditions to be met :
1) The peripheral speed of the cutter blades at the time of cutting should be equal to
Paper Linear speed
2) Balance rotation either speeded up/ down to achieve cut length required
3) Nearest Motion profile exhibited by Grashof Criterion- Double draglink transmission

7. Electrical Cutter Drive design for single rotating knife/ Dual rotating knives version
Special Mention: Application of Grashof law Mechanically in cutters paves way for Development
in Electrical drive technology

8. Comparison of Electrical synchronized drive systems vs. Mechanical drive systems
1. Higher machine productivities – 350 mpm against 120 mpm (Metres/ Min.)
2. Improved cut length and diagonal cut length accuracies within +/- 0.38 mm against
+/- 1 mm
3. Total avoidance of Mechanical transmission wear and tear – Improved machine up
time availability and consistent performances
4. Longevity of Machine life – improves multifold.
5. Machine performance degradation is avoided.
6. Larger MTBF achieved
7. However Electrical system performance Maintenance requires higher skill set with in depth
understanding

9. Cam Motion profiles for simulating Grashof law
1) The previous slide shows the cam profile requirement
2) The following motion profiles may be used for simulation – 1) The trapezoidal profile

10. Cam Motion profiles for simulating Grashof law contd….
2) Triangular Profile with smooth speed transition section….
3) Sinusoidal profile- Totally smooth speed transition sections –short and long cut lengths

11. Induction & history of Electrical drives in Dual rotating knives cutters
1. Initially AC fixed speed motors with mechanical variators and double drag link transmissions were used
to achieve cutter motion profiles
2. With developments in DC Motor drives and computing systems like yesteryear PLCs, the DC Motors and
drives were employed vary the speeds of the cutter drums in ratio to Paper draw section retaining the
Double draglink transmissions.
3. Subsequently with Low Inertia DC Yoke motors thru gear transmissions and Flywheels avoiding Double
drag link transmissions profiles generated by PLCs of yesteryears were used for driving cutter drum in
synchronism to Paper draw sections machine speeds going up to 250 mpm and cut length accuracies +/-
0.5 mm
4. Post millennium year, with advent Asynchronous low speed servo motors and IGBT drives
along with planetary gear heads were deployed for better performances
5. Presently Permanent Magnet Synchronous servo motors with drives are very gainfully
employed with very high compactness and higher performances.

12. Single rotating knife machines illustrations – Paper Industry

13. Dual rotating knives machines illustrations – Corrugation Industry

14. Dual rotating knives machines illustrating video – Paper Industry

15. Comparison of Motion profiles Trapezoidal vs. Triangular vs. Sinusoidal
COMPARISON OF CUTTER MOTION PROFILES
Sr.
no. Parameter Trapezoidal Profile Triangular Profile Sinusoidal Profile
1 Acceleration
Least constant
throughout speed
change
Higher than
Trapezoidal and
constant throughout
speed change
Varying continuously
and highest peak
2
Speed transition
points
Abrupt. Need To
introduce smoothening
formula at speed
transition points
Abrupt. Need To
introduce
smoothening formula
at speed transition
points
Naturally smooth. No
requirement of
additional smoothening
corrections at all
3 Peak speeds Higher than Triangular
Least among the
profiles
Highest among the
profiles
4
Mechanical
transmission
suitability Fairly OK
Highest stress on
Transmissions
Lowest stress on
Transmissions

16. Motion profiles of Sinusoidal Dual rotating Knives cutters – Speed, Position and
cutter MotorTorque

17. Moment of Inertia Mismatch benefits – from new developed control algorithms
1) Moment of Inertia mismatch i.e Source MOI/ Load MOI > ½ in erstwhile PID control
algorithms
2) Source MOI/ Load MOI =/>15 in Advanced Feed forward Control Algorithms
3) Therefore the Prime mover can be sized much lower
4) Peripheral and accessories to the Prime mover are sized lower – Drive ratings, Cables,
Electrical switch gear, transformers etc.
5) Prime mover Moment of Inertia reduces thus motion becomes smoother
6) Reduced demand on Prime mover moment of Inertia – Direct Motor Load driving systems
Become feasible and to achieve better performance, higher productivity

18. Feed forward control algorithms for cutter Motion Profiles
Definition -Feed forward augmentation is a prediction technique that estimates the output from a
proportional-integral-derivative (PID) control algorithm without waiting for the PID algorithm to
respond. Feed forward reduces the error faster or keeps the error smaller than relying on the PID
algorithm alone.
1) Meaning the system is prepared to be in a specific position/speed/ torque correcting only the
small errors that creep in.
2) This reduces the burden on PID to correct large errors as in conventional control algorithms
3) Reduced error correction demands – reduced Oscillations
4) Reduced error correction demands – Highest accuracy achievements

19. Successful examples of Retrofits from Double drag link configurations to Direct Electrical drive
configurations
1) Jagenburg Duplex 3.2 mtr wide Dual rotating knives sheeter of 1960 origin
a) Machine from 1960 - 2004 run with Double draglink transmission
b) 2004 – 2016 – Machine performed with AC Servo motor(28 kwcapacity) + Planetary
Gear head ( with<3 arc min. back lash) Combination retrofit.
c) 2016 onwards – 180kw/ 500 rpm AC Servo motor without any mechanical
transmission between Motor and cutter shaft
2) Jagenburg Simplex 1.6 mtr wide Dual rotating Knives sheeter of 1980 orgin retrofitted in
2007 with Split synchronized sectional DC drives and retaining Double drag link
transmission
3) Many more similar combinations and configurations of deployment of Servo technologies
in Steel/ Plastic Film/ Aluminium Foil converting Industries

20. Any theoretical laws/criteria/rule/discovery can be applied gainfully if properly identified
and if the application targets to achieve the technological philosophies in letter and spirit
with adjusting the applications to suit the empirical conditions. This paper is an endeavor to
highlight how application engineering plays an important role in the growth of technologies
improvement of Man/ Machine productivities.
For every complex situation/ challenge, there always a simple dormant solution. If identified
aptly, the techniques can improve multifold yielding desired solutions and results
Conclusion

21. References
1. M Ekambaram: Growth, Developments and Future Prospects of Solid State Switching Devices
IE Annual Conference – 2002, Hyderabad
2. Shahid Maqsood, Theory of machines, Kinematics and machines
3. ORMEC Application Highlights, Rotary Knife Cut-off
4. Application building block by ORMEC
5. Maxsons Automatic Machinery company, Sheeter manufacturers from 1906
6. Practical experiences of Author in Dynaspede Integrated systems Pvt. Ltd and Walmsleys
India Pvt. Ltd.. in 2004 and 2017
7. Astro system, Automation Applications Handbook
8. Brian Thomas Boulter, Applied Industrial Control Solutions, 2002 IEEE IAS Annual Meeting,
Applying Drive Specifications to Systems Applications: Part III Position Regulation
. Motion control - Application note - Rotary Cutter AN00226-003 by ABB.
9. Study on control strategy of the rotary synchronous fixed-length cutting system – Huazhu,
Wu, Naihao Luo , Changyou Wang, Dalian Jiaotong University, Dalian, China
10. https://www.youtube.com/watch?v=h8bz4ni6mdY – for brief on Grashof Law