Analog-Digital Tension Controllers

The proper control of web tension is especially important for maintaining good quality in coating and laminating processes.

For example, in coating processes, variations in web tension can lead directly to variations in coat weight and may cause spreading problems leading to carry over onto rollers. Even variations across the web width can cause quality problems with Meyer bar, air knife or reverse roller coating systems and a display of right, left, or total tension can be invaluable in counteracting this.

In the case of laminating lines it is not only the absolute tensions, that are important but also the relative tensions of one laminated material to another. These must be correctly related to the stress/strain characteristics of the material if subsequent distortion due to differential contraction is to be avoided. Curl is often a particularly acute problem when sheets are the end product. Montalvo provides tension control systems which can automatically maintain the correct tension ratio between the materials in spite of all the variable data such as reel diameter, acceleration/deceleration and non-linearity in the system.

Coating and laminating lines also present more difficulties in respect of the use of isolating wraps and nips than many other converting processes.

When this is combined with the effects of drying ovens, especially flotation types, where the tension must be maintained at a constant low value, the proper control can be problematic.

The Montalvo X-3400ce analogue/digital and the S-3100ce digital tension controllers have been designed for maximum controllability irrespective of the materials and machine variables. These controllers are generally used in conjunction with Montalvo’s load cells (transducers) and/or indicators/amplifier modules for a complete web tension sensing and control solution.

The X-3400ce is the latest closed-loop controller from Montalvo. The unit can utilize load cell (transducer) input signals and a ‘Progressive PID’ regulator. It can be configured for use for intermediate control positions as well.

The S-3100ce provides accurate and repeatable control on all web application employing a torque device. It is ideal for unwind, intermediate and rewind tension applications. Employing a ‘diamatic’ control algorithm the S-3100ce ensures uniform response, regardless of roll diameter. This model is both fast and precise and includes a non-volatile memory for the storing of control parameters.

Features also include semi-automatic calibration and control tuning, user adjustable soft-start and anti-coast; sample/hold/ratio splice function and bumpless transfer between auto and manual, as well as rewind taper.

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