Drive makes light work of winding machine

Edited by the Engineeringtalk editorial team Jun 14, 2002

A new winding machine developed by Gatfield Systems can switch instantly between coiling up and paying out without imparting any extraneous tension to the cable.

A new winding machine developed by Gatfield Systems can switch instantly between coiling up and paying out without imparting any extraneous tension to the cable.

This is being achieved simply and elegantly using only a standard variable speed drive, supplied by Toshiba's European Automation Partner TM Automation.

There is no need for a costly PLC or even an extra control board inserted into the drive, instead the Toshiba's twin reference signal inputs are used in conjunction with the machine's dancing arm.

The reference signal from the dancing arm is fed to both of the drive's inputs.

Internally the drive reverses the polarity on one signal, so that on one signal 0V represents 0rev/min and 10V (max) represents full speed, while one the other signal 0V represents full speed and 10V is 0rev/min.

This allows a smooth switch over from winding to paying out.

Coiling is a vital part of the manufacture and distribution of wire, cable, hose and other products such as draught excluders that are continuously extruded or drawn.

During manufacture it is collected from the production machinery by winding it onto very large drums.

It may subsequently be rewound onto smaller drums of a size suitable for distribution along the sales channels.

Gatfield has been making winding machines for many years, producing a great many variations of the basic design.

The fastest machine they ever produced ran at 500m/min; the slowest was for a special PTFE-based product that was extruded at 3m/h.

Key to achieving a neat lay of product onto the drum or alternatively a perfectly controlled pay out is precision monitoring of a vital parameter of the product in motion.

This could be the tension, speed or torque, depending on the type of product being wound.

From this a reference signal is generated and fed into the PID controller on board the Toshiba inverter.

TM automation has set up the PID controller to monitor the parameter in real time and ensures it remains within predefined limits.

If the parameter is moving out of tolerance, the dancing arm instantaneously alerts the drive to speed up or slow down to correct the speed of rotation of the drum and thus arrest the trend.

Indeed the drive is constantly adjusting the speed of the motor to compensate for the change in the effective diameter of the drum as product is laid onto or unwound from it.

Thus as the rotational speed is adjusted the linear peripheral speed remains constant, being matched to either (during wind up) the rate of manufacture or the optimum speed for rapid but controlled unwind.

This apparently simple speed-adjusting requirement actually takes considerable management, particularly if the just manufactured product is fragile, or if precise lengths need to be wound onto each drum.

For many years the industry standard for wind/unwind machines was such that speed and direction of rotation was changed in a series of discrete steps.

Now however, the latest generation of Toshiba drives created the opportunity to develop the wind/unwind dynamics to a level previously thought to be practically impossibly.