KraussMaffei Berstorff and GfA De Pryck & Co mbH have joined forces and developed an innovative concept for the production of jointless bandages use in tire treads to absorb extremely high forces. The jointless bandages are made using a cap strip line which is delivered ready to plug in and composed of a rubber processing extruder with downstream gear pump and a hydraulic crosshead die. The die is designed for coating 128 cords at a time with a rubber compound and to combine them to 16 cap strips that are subsequently wound around the belt during the tire assembly. Traditionally, tire producers manufacture these bandages by calendering. During the subsequent cutting process, however, the longitudinal knives damage or even partly sever the outer cords of the bandage, which substantially affects the tire quality.
The turnkey package - jointly offered by KraussMaffei Berstorff, leading supplier in the field of extrusion lines, and automation specialist GfA - covers the creel designed to take 128 spools with nylon or hybrid cords, the extrusion line with gear pump and hydraulic crosshead die up to the downstream equipment such as cooling drum assembly, material accumulator and the 16-station winding system. The line achieves a throughput capacity of 40 m/min at constant output and excellent extrudate homogeneity. The final die is fixed by means of a hydraulic clamp and can easily be replaced when changing the material. The crosshead is also equipped with a hydraulic system for opening and closing, which substantially facilitates cleaning operations. A creel change takes just 30 minutes. The wound-up spools can be changed at full line speed and the line can be operated continuously for up to ten hours due to high degree of automation.