: Production :

Design, construction and automation of industrial machineries and plants: automatic winders for plastic films, polymer gear pumps, reduction gearboxes for single and twin-screw extruders.


                                     :: Gear boxes | Single screw extruder | Twin screw extruders




With the same schedule and technological method used in the building of gearboxes for single screw extruders, ALFATECH has produced also the line of gearboxes for twin screw extruders, characterized by the kinematic disposition of the gears, which drive the inside screw (motor side) such to cancel the dynamic radial loads caused by the same gears and to increase the bearings life. Consequently this condition implicitly gives the possibility to operate also with high speed of the screw.

Loading capabilities
• Gears service factor according to the A.G.M.A. 218.01 standards and relevant specifications regarding control calculation of the bending stress at the basis of the teeth and of the specific face pressure. Other special algorithms are also applied to determine the geometrical factors defining correct toothing mathematically;
• gear efficiency;
• thermal capacity;
• heat transfer.

Dynamic conditions of the elements
• Elastic line of all the shafts:
• deflection;
• bending moment;
• shearing stress;
• bending stress;
• combined bending and torsion stress;
• shearing force;
• theoretical life of all the bearings;
• peripheral speed of gears;
• bending critical speed of high-speed shaft;
• tensile strength of thrust block bars;
• dynamic loads on anchor bolts.

Construction characteristics
The main characteristics of our twin-screw reduction gearboxes are:
• Cast-iron housing;
• Gears of hardened, tempered and grinding surfaces steel according to DIN<=6;
• Rolling bearing SKF or FAG; multistage axial bearing;
• Displacement of the axial loads of the screws by steel platens connected by strong connecting roads;
• Forced lubrication by means of a pump and heat exchanger for oil cooling, placed on a plate to be fixed to the wall under the gearbox in the back part;
• Control of axial load (only external screw) by means of a loading unit;
• Projection of low-speed shaft and barrel coupling to extruder according to customers drawings;
• Projection input shaft extruder side.

1 Informations


ALFATECH S.r.l. Via Lecco, 12 - 21049 Tradate (VA) - ITALY - P.I. e C.F. IT01857710121 Reg. Soc. VA16931 - C.C.I.A.A. V 212333 Cap.Soc. 98.800 i.v. 2010. All Rights Reserved.