Individual yarn tension controlled Creels

Individual yarn tension controlled Creels
 

One of our customers asked us to offer a Creel with individually controlled tow tension. A long standing wish which up till now could only be rewarded at high investment costs. Using its long time experience with creels and operating UD machines, Van Wees came up with a new design. The principle of applying the yarn tension is based on the spring loaded braking belt principle which we have used in thousands of spool positions.

The main challenge lies in the use of components with reasonable prices. The yarn tension measurement, one of the main components, is done with a new sensor. This sensor is developed by Van Wees, using state of the art components. The sensor is placed between two bars. These two guide shafts make sure that the angle on which the yarns push onto the tension sensor is constant. The yarns pass only non-rotating parts, making sure there is no risk of fiber wrap.

The brake torque on the spool is generated with a spring loaded brake belt, as mentioned earlier. Each spool holder belt is equipped with a linear actuator which increases or releases the spring tension.
The output value from the sensor is used for the adjust­ment of the tension through a feedback loop. If the yarn tension is too high, the actuator will move in the direction which lowers the spring tension and therewith the brake torque on the spool. Too low tension will generate the opposite movement, regulated by a PLC. The actuator is equipped with end switches preventing damage of the actuator.

From the information of the sensors, warning signals can be generated for fiber wraps on the spools and/or broken filaments. Yarn tension ranges can be set in accordance with customer wishes.

BarsFor the Van Wees Carbon and Glass creels we have updated the design for carbon and glass tows. Each spool holder is foreseen with a full bobbin simulation bar to bring the tow at the correct height. For guiding the yarns inside the creel, intermediate boards are mounted with oval eyelets. Van Wees has designed these eyelets in such way that heavy glass roving and carbon tows will remain flat and do not fold during their travel.
All bars and eyelets are made of yarn friendly material to prevent damaging of the yarn. The intermediate guiding is a strong, helpful feature of the Creel, they prevent twist, keep the yarn flat and do not damage the fiber.