Compensation functions optimise winding applications
Siemens has developed functions for its Simotion motion controllers that, it says, will improve the speed, reliability and quality of the winding operations used in converting applications such as processing corrugated cardboard or web materials, and manufacturing battery electrodes.
Winding onto non-circular (near-elliptical) cylindrical bodies creates web length changes between the material support point and the deflector roller. These were previously compensated for mechanically, or by using a variable winding speed.
The new developments - which will be demonstrated at the 2017 Hannover Fair - include a prismatic winding function which compensates for path length differences on non-circular winding bodies, and a Learning Error Compensation (LECo) function that compensates for periodic disturbance variables in the process, and is claimed to restore process and product quality rapidly. Deviations, such as position errors on a process axis triggered by mechanical shock, are said to be largely compensated for after just one cycle.
The new prismatic winding function calculates cyclically, in advance, the support points of the material on the deflector roller and winding body, and feeds these into the controller. The benefits are said to include better winding quality, higher machine speeds and improved process reliability.
The self-learning LECo application supersedes dynamic position controllers which correct position errors of the process axes caused, for example, by a mechanical shock, but only after a delay. By monitoring the process axes continuously, the new function detects deviations rapidly, calculates the pre-control value on the basis of the following error, and feeds this to the controller in the next cycle. Deviations are largely compensated for after one cycle. In the following cycles, a learning algorithm monitors the result of the compensation continuously, and fine-tunes the drive control, thus also improving the process accuracy.