Gearboxes for the rubber and plastics industry are either mixer gearboxes or extruder drive gearboxes.

 

Rubber mixer and mill gearboxes are designed to accept fluctuating loads and high powers. The gearbox output shafts are generally connected to the mixer by mill spindles or gear couplings. The twin output shafts are arranged to rotate opposite to each other. This type of gearbox is also used for twin screw extruders, where additional thrust assemblies are incorporated.

 

Extruder gearbox designs incorporate a substantial thrust bearing assembly on the output shaft to counter the thrust from the extruder screw. The gears are also required to be smooth in engagement so as not to affect the extrusion process by vibration. The input shafts need to be designed for vee belt drive loads and occasional overload from cold starts.

 

They are available for the following types:

■Gearboxes for internal mixers - both tangential and intermix types

■Continuous mixers gearboxes

■Two roll mixing mills gearboxes

■Gearboxes for calenders with 2 or more rolls

■Extruder gearboxes

■Gearboxes for cutting shears

■Gearboxes for BOPP lines - film stretching