F-81682.T4AR Precision Bearing In Twin Screw Extruder Gearboxes

 F-81682.T4AR Precision bearing in Twin Screw Extruder Gearboxes

F-81682.T4AR f-81682.t4ar BEARINGS specification as following:

Tandem roller bearing structure :

Tandem 2 rows(T2AR),

Tandem 3 rows(T4AR),

Tandem 6 rows(T6AR),

Tandem 7 rows(T7AR),

Tandem 8 rows(T8AR)*

Tandem thrust bearings are produced by only through orders

How to choose the tandem cylindrical roller bearing type:

Three pieces of information are necessary when selecting a suitable tandem bearing:
– the maximum possible bearing OD
– the desired calculated rating life under operating load and speed
– the maximum screw pressure.

The maximum possible bearing OD results from the intermeshing of two screws in the case of twin screw extruders. In the process, the crest diameter of one screw contacts the root diameter of the other screw. The resulting tight center distance and the output shaft near the
tandem bearing limit the radial design space. The length of a tandem bearing is normally not a crucial factor in bearing selection. For this limited envelope, tandem bearings are available in the 31.5 to 900 mm OD range.
The required calculated rating life under operating load and speed is generally between 20,000 and 40,000 hours for extruder gearboxes. Smaller gearboxes such as those used in extruders for
laboratory applications have shorter life requirements. Here, a value of 5,000 hour is sufficient. Another factor to consider in bearing selection is the maximum screw pressure. Due to the deformation of the components and the resulting stresses, a maximum permissible axial load Fa max may not be exceeded. The value for Fa max, the dynamic load rating C as well as the static load rating C0 can usually be found in the tandem bearing delivery drawing.

How to Mount Tandem Bearings:

Tandem bearings are mounted with a loose F7 fit for the housing and f6 for the
tandem bearing shaft. A loose fit is necessary to allow the axial shifting (deflection) of the washers, rings and sleeves. The seating surface of the adjacent structure (housing and shaft) should be designed to have a perpendicularity tolerance to DIN ISO 1101 and qualities IT4 to IT7
(depending on the diameter range). For the mating structure, care should also be taken to ensure that the contact diameter indicated on the delivery drawing is maintained. The contact diameter
(support diameter) for the shaft shoulder may not be lower than the diameter indicated, and the contact diameter for the housing must not be exceeded. Insufficient support will not only cause an unequal load distribution but also an increased washer deformation (washers GS 0 and WS 0), which in turn will result in increased strain on the components.

Tandem bearings have proven effective principally in gearboxes

for single and twin screw extruders in the rubber and plastics
industry.
Other possible applications include:
■ deep hole drilling equipment
■ friction welding machines.