Drive secret behind converting machinery

Converting Solutions is using a servo motor-drive package from Control Techniques Dynamics to develop a state-of-the-art slitter/rewind machine.

Converting Solutions, a manufacturer renowned for its quality in the converting machine manufacturing market, is using a servo motor-drive package from Control Techniques Dynamics to develop a state-of-the-art slitter/rewind machine.

Historically when using DC motors, as the machine speed increases (ramps up) and decreases (ramps down) the pre-set target is passed and must then back-off achieving its goal.

Problems can arise with the material at this point by allowing a loop to occur momentarily, so loosing control of the web tension.

Using AC servo, the TDC 150 slitter/rewinder is able to resolve this problem and maintain high acceleration and deceleration rates ensuring "what you set you get".

The TDC 150 has been developed for use with delicate coated materials such as 12 micron hot stamping foils, 4.5 micron TTR (thermally transferred ribbons), pigment and thermal materials or any products with small diameter rolls and delicate and sensitive coatings, e.g as used for bar coding.

It can handle web widths up to 1000 mm and has a maximum unwind diameter capacity of 600 mm.

It unwinds, out slits the material up to 25 times and rewinds up to 150 mm diameter on 25mm and 12.5 mm cores.

This is carried out from standstill to 300 mpm in 5 seconds and uses the same ramps down speeds to stop.

A total of four, 75mm Unimotors, three Unidrive Uni1401 3.75kW and one Uni1402 1.1kW are incorporated into each TDC 150.

One Unimotor controls the parent roll, via a dancer roll, producing a closed loop tension system which solves the problems of inertia compensation between the unwind and the driven pull rolls section.

A second Unimotor operates the driven pull rolls which control the master speed reference.

Two further Unimotors operate the rewind in torque control, to provide excellent tension accuracy so that a Duplex Turret rewinding system can quickly change and provide fast, production speeds.

"The TDC 150 slitter rewinder uses good, solid engineering, and is about control of the web", explained Barry Taylor.

"Delicate web coatings, fast ramps up and down of speeds, inertia control and compensation - all these factors have been achieved with the help of servo." " Servo has also helped us gain some additional features for the TDC 150", continued Taylor.

"As Control Techniques Dynamics motors are brushless, they require very low maintenance and being smaller than DC motors, the overall size of the machine is far less.

This is a very important feature where factory space is at a premium." There are three tension zones controlling the web tension in the parent (mother) rolls, the slitting sections and in the rewinding of the slit coils.

AC servo was the only system capable of providing the technical criteria required to produce the high dynamic performance, high resolution and excellent position and speed control needed for this application.

"We have developed the TDC 150 because customers are introducing new product ranges, many with expensive and specialised coatings", concluded Taylor.

"They require an exceptional tension control of the material combined with fast production speeds.

The servo motor/drive package from Control Techniques Dynamics has made this a practical reality.".

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