Method and device for operating a drawing line or drawing unit

A method for driving a drawing line or drawing unit for drawing of tows having polymer filaments comprising a plurality of driven drawing rollers for drawing the tows and a plurality of separately controllable drive units, one of the plurality of separately controllable drive units being operably connected to each of the driven drawing rollers for individually controlling the torque on each drawing roller, said method comprising:

• comparing a measured torque on a given drawing roller of the plurality of drawing rollers to a setpoint torque for the given drawing roller;
• and
• controlling the drive unit controlling the given drawing roller to bring the measured torque closer to the setpoint torque,
• wherein said individually controlling the torque on each drawing roller is done automatically through gradual approximation based on a setpoint torque curve or a setpoint torque characteristic,
• wherein each drawing roller is controlled to run at a specified rotational speed based on a current control,
• wherein said individually controlling the torque is continued until the torque on each drawing roller meets the setpoint torque and each drawing roller reaches the specified rotational speed, and
• wherein torques of the separately controllable drive units are controlled until a same torque is given throughout,
• the method further comprising:
• driving a first one of the plurality of drawing rollers at a previously determined speed;
• determining a speed of a subsequent one of the plurality of drawing rollers and a draw ratio of the first one of the plurality of rollers and the subsequent one of the plurality of rollers;
• starting the drawing line at a free selectable starting draw ratio;
• for a set of intermediate drawing rollers between the first one of the plurality of drawing rollers and the subsequent one of the plurality of drawing rollers, setting the speed of each intermediate drawing roller to be between the previously determined speed and the speed of the subsequent one of the plurality of drawing rollers;
• placing a tow on the plurality of drawing rollers and initiating a torque optimization process by monitoring and adjusting the torque on each of the intermediate drawing rollers so that the torque on each of the intermediate drawing rollers approaches a setpoint torque for said each intermediate drawing roller;
• and
• accelerating the rollers of the set of drawing rollers to a final speed.

A method for driving a drawing line or drawing unit for drawing of tows having polymer filaments comprising a plurality of driven drawing rollers for drawing the tows and a plurality of separately controllable drive units, one of the plurality of separately controllable drive units being operably connected to each of the driven drawing rollers for individually controlling a torque on each drawing roller, said method comprising:

• comparing a measured torque on a given drawing roller to a setpoint torque for the given drawing roller;
• and
• controlling the drive unit operably connected to the given drawing roller so that the measured torque on the given drawing roller of the plurality of drawing rollers approaches the setpoint torque for the given drawing roller,
• wherein said individually controlling the torque on each drawing roller is done automatically through gradual approximation based on a setpoint torque curve or a setpoint torque characteristic and wherein said individually controlling the torque is continued until the torque on each drawing roller meets the setpoint torque,
• wherein torques of the separately controllable drive units are controlled until a same torque is given throughout, and
• wherein a first of the plurality of driven drawing rollers is driven at a fixed rotational speed and the rotational speed of the other of the plurality of driven drawing rollers increases until reaching a specified rotational speed.