Calender for the extrusion of film

Project Calender for the extrusion of film
Wear 2019
Calender for the extrusion of film

The calender is integrated into an extrusion line for battery separators, directly after the extrusion tool. It gives the extruded special plastic mixture its final shape (thin film) before it goes through further chemical and thermal processes.

The process involves 2 rollers arranged one above the other, manufactured with very precise concentricity and cylindricity, rotating in opposite directions. The two rollers are each driven separately by powerful, geared servo motors. Given the extreme thin gauge of the end product (film less than 0.1 mm thick), it is important to maintain the same circumferential speed of the two rollers, knowing that the diameters of the rollers may be different.

There is a gap between the rollers, adjustable to within 0.01 mm, through which the extruded mixture passes and thus reaches its final shape, or thickness. The exact width of the gap is adjusted by means of high-precision, electrically driven screw jacks on either side, which can move the bearing blocks of the upper roller in a vertical direction.

The end product is given a special profile on both sides, which is produced by the rollers. Many different profiles are possible, which is why it is often necessary to change the rollers in the calender quickly, but nevertheless reliably and precisely. This is why another special feature here is the possibility of quickly changing the highly stressed and very precise bearings of the various rollers.

The safety aspect always took precedence in the engineering of the calender rollers.