The next step in obtaining the necessary good winding foundation is to start winding with as much roll hardness as possible.
The larger the roll's final wound diameter (the taller the structure) the more important starting on a good solid foundation and winding a progressively softer roll becomes.
The winding tools to develop roll hardness are web tension, nip pressure (from a pressure or lay-on roll or winding drum) and winding torque from a center drive when center/surface winding film webs.
The sense signal depends on the ratio of the impedance of the two windings. Using the measurement of the impedance ratio is very advantageous.
The impedance ratio measurement method requires that a current run through the motor windings at all times.
* The winding film's weight and the lay-on roll's weight, as well as web tension, should not affect the nip loading.
Torque winding is the force induced through the center of the winding roll, which is transmitted through the web layers and tightens the inner wraps.
There are three basic winding processes used for web materials: center winding, surface winding, and combination center-surface winding.
Instead of pneumatic or hydraulic pressure, Reifenhauser uses a servo drive on a shaft to create mechanical pressure on the contact drum for surface winding. That servo pressure can go as low as 50 N (11.25 lb), making it possible to wind thin, sticky film in pressure rather than gap mode.
Kiefel a few years ago bought Wintech Winding Technology in Switzerland and the high-end orbital-winder business of Christian Maier GmbH in Germany.
Alpha Marathon, which builds turret winders for blown and cast film, recently introduced a high-speed rewinder for gusseted film, capable of winding at 1200 ft/min with fully automatic roll changes every 20 sec.
- New winder for biaxially oriented films is an unusual dual-turret machine in which the shaft in the winding position oscillates up to 3 in.
Individually driven shafts can alternate between surface and gap winding (1-20 mm range).
While flat-crush strength is an excellent indicator of a core's ability to withstand transportation and handling, it does not provide the best forecast of a core's strength under winding.
Just this year, however, Sonoco patented a device for duplicating the radial forces experienced by a core during winding. This hydraulic device exerts radial pressure on the core OD while simultaneously inhibiting the core from going out of round.