AUTO WEB TENSION CONTROL SYSTEM

Introduction :

Practically all continuous web processing machinery require perfect material tensioning.  During the working process, constant stretching and pulling of the web has to be maintained with controlled tensioning for consistent processed material quality.

In fact, most web processing machines are designed to provide a certain degree of tension control with proper sizing of drum rollers and proper setting of machines, nevertheless problem do arise from inconsistent and rapid operating speed changes, Out of roud rolls, Uneven Drag, Slight hastily unwinding or rewinding or Inconsistent feeding of material and/or Slight error of Machine operator.  All these or any one of these result into inadequate tension control giving rise to poor quality of processed material, loss of time, Wastage of costly material, which generally result into financial loss and goodwill of the company.

After studying the existing problems in various type of available web tension control system, our team of R&D Engineers have developed and designed.

Type of Sensors used for these application are :

1. Manual judgment of tension with feel.

2. Dancing Rollers

3. Load Cells.

4. DC Motor Current

All these above brakes except DC motor are based on Friction only.  Frictional brakes are normally constant at one speed and if the speed varies thus the braking effect changes drastically.  During winding and unwinding process, RPM of the roll varies this the frictional braking effect changes.  Frictional brake characteristic is very nonlinear, so the constant controlling of the tension on the web is a difficult task.  Hence, these braking system require to perform according to the Diameter, Machine Speed, Roller RPM, type of material etc.

It is well known that if the things can be managed electrically/electronically, then mechanical possible ways are avoided i.e. if in one application variable speed is required then variable speed electrical/electronic drive is preferable instead variable speed gear.  In Diesel Locomotive, first Diesel engine generates electrical energy and than a electrical motor controls the rest.  A car running with fuel like diesel or petrol requires very complicated engine, but car running with electrical power requires very simple mechanism.

Hence, it is universally accepted that controlling Electrical/Electronic drive are easier than mechanical.

Theory:

Considering the draw-backs of above systems, we have developed a new system which takes care of all above.  This system takes feed back from Speed of Web, RPM of Roll. D.C. Power of the motor and with the complex calculation through Microprocessor chips and controls D.C. Motor through generating required Electromotive Force with the help of Solid State Controlled Rectifier.

Selection Criteria of D.C. Drive power depends on:

• Type of Material (Its Tensile strength).

• Diameter Built up Ratio i.e. Ratio of Maximum Roll dia and Core dia.

• Machine Speed.

Selection of motor is proportional to all above three points.

Main Features:

• Avoidance of Telescopic winding. Hence, obtain Tight and Transportable rolls.

• In Printing, reduction in Linear and Side Registration problem.

• Reduction in Web Breakage.

• Material surface remain untouched * It does not require separate transducer or Load Cell type sensor for tension measurement.

• Considerable reduction in wastage of costly processing material.

• Reduction in problems of `Out-of-order' rolls at unwinding.

• Tension is controlled from zero to maximum at any speed which is limited in magnetic clutch type of system.

• Specialized machine operators are not necessary.

• Short Pay back period.

Technical Features:

• Digital settings upto the resolution of better than 0.1%.

• Digital taper tension control.

• Digital presetting of Tension avoids trial and error in setting tension every time.

• At starting and stopping of the machine, tension is controlled in such a way that there is no loose winding at winding and unwinding side.

• Protection against the jamming or overloads due to process material or any internal fault of the machinery. Hence, it helps in avoiding damages to the machines and reduction in down time.

• When machine stops, torque on the motor goes in the sleep mode which protects overheating of motor.

• All the parameters are user's programmable which is the speciality of this system.

Applications:

• Paper Manufacturing Machines

• Paper Converting Machines

• Paper Slitters and Rewinders

• Roto Gravure Printing Machines

• Flexo Printing Machines

• Continuous Stationary Presses

• Plastic Films Lamination and Slitting Machines

• Foils Processing Machines

• Coiling and Decoiling in Metal Industries

• Wire Drawing Machines

• Magnetic and Adhesive Tapes Machines

• Blown Film Extrusion/Tubing Machines

Our Other Controllers for:

• Specialized Custom-built Slitting Machines

• Specialized Lamination Machines

• Renovation and Automation of existing Rotogravure Machines for higher speed and less wastage

• Automatic Pouch making Machines

• Speed Controlled Heating System with Power Saving feature

• Speed, Length and On-Line Stretch Measurement

• On-Line Average Weight Measurement

• Multi Station Speed Synchronization

• 3-Drive, 5-Drive Synchronization Systems

• Specialized Custom built 2-Drive Synchronized Slitting Machine

• PID-based Heating Control System

• Speed, Length and On-Line Stretch Measurement System

• Multi-Drive Synchronization