Home > Toy Guns >

8 stage cylindrical roller thrust bearing

Categories Cylindrical Roller Thrust Bearing
Brand Name: BCM
Model Number: 8 stage cylindrical roller thrust bearing
Place of Origin: China
MOQ: 1PC
Price: USD1-1000 per pc
Payment Terms: L/C, T/T, Western Union
Supply Ability: 1000PCS per month
Delivery Time: 5-8 work days
Packaging Details: seaworthy package
  • Product Details
  • Company Profile

8 stage cylindrical roller thrust bearing

8 stage cylindrical roller thrust bearing


Multi-stage cylindrical roller bearings (Tandem bearings) have very good characteristics of limited radial space, high axial forces, equal support of all the rows of rollers and long operating life, and is the ideal spindle of parallel screw extruder.

The tandem bearings provided by our institute has the following types: double rows, three rows, four rows, five rows, six rows and eight rows, we also provided bearings with shaft and sleeve barrel. Customers can have their own selections according to center distance of screws, space and load .

We also accept the orders of other dimensions.

Application of tandem bearings

When using tandem bearings, following recommendations should be adhered :

(1) Preload: 1% of the dynamic basic load rating.

(2) Radial guidance: full complement cylindrical roller bearings .

(3) Eliminate tilting: the supporting parts must be machined to eliminate anytilting.

(4) Mounting tolerances: recommended the following mounting tolerances:

shaft f6 and housing bore F7.

(5) Lubrication: tandem bearings must always be lubricated by oil circulation .

Tandem Thrust bearings are comprised of “stages” which include precision

ground and matched thrust plates and compression sleeves separated by

cylindrical roller assemblies. This design enables the Tandem Thrust bearings

to provide a solution in a radial restricted envelope. The bearings are available

in multiple stages, 2-8 to accommodate your designrequirements. Depending

on your preference, these bearings are available in a wide variety of sizes and

options as illustrated on the pages to follow.


Features and Benefits

1.Minimal Backing Support Requirements

2.Space Saving Design

3.Matched Precision Ground Rollers

4.Machined Brass Roller Riding Retainer

5.Precision Ground Inner and Plates

5.Precision Ground Inner and Outer Compression Sleeves


Tandem Bearings in Twin Screw Extruder Gearboxes


Modern twin screw extruder gearboxes with a high power density such as those

used in the processing of thermoplastic materials are machine elements that must

provide a high degree of reliability in operation. The tandem bearingssupplied by

a well-known rolling bearing manufacturer have been used in harsh environments

fordecades. In spite of increasing demands placed on these bearings, like the

requirements for deep foundation drilling equipment or friction welding machines,

these products have proven themselves as reliablemachine elements. These tandem

bearings represent an excellent solution for applications requiringa small radial

design envelope,high axial forces and long life.


1.Tandem Bearing Design

Tandem bearings consist of several coaxially arranged thrust cylindrical roller

and cage assemblies. Two, three or four thrust cylindrical roller and cage

assemblies can be used, corresponding to product designations M2CT.., M3CT..

andM4CT.. respectively. Six row and eight row tandem bearings (M6CT.. and

M8CT..) are also available. These products consist of two triple row and two

four row tandem bearings respectively.

The special elastic system of matched rings and washers made from hardened

rolling bearing steel ensures that there is an equal load on all rows regardless

of the magnitude of the axial load.


2.Tandem Bearing Operation

To meet the requirement that all rows support equal portions of the axial forces from the extruder screw regardless of the load ratio C/P, the shaft sleeves and housing sleeves are specially designed so that the same deflection is achieved for each row. The geometry of the rings thus plays an important role in providing the optimum flow of power in the bearing. The shape of shaft washers and housing washers primarily effects the load distribution on the length of the cylindrical rollers. The design of shaft and housing washers allows both components to receive the same polysymmetric deformation. Although the washers underload are subject to elastic deformation,both raceways nonetheless remain almost

parallel to each other. Rolling element tilting or edge loading on the rolling elements, which lead to reduced service life, can thus be eliminated.In addition to the equal deflection on each row mentioned above, in the case of six row and eight row tandem bearings the load distribution between the three row and four row tandem bearings must be achieved corresponding to their load carrying capacity. This can be done by matching the shaft sleeve and the housing sleeve.


3.Bearing Selection

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 hours 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.

The value Fa max refers to the permissible strain on the components (rings, washers,etc.). For this reason, the maximum screw pressure should be known. On the other hand, the dynamic and static load ratings refer to the entire rolling element set. Since the value for Fa max is always lower than C0, the static load rating C0 is not relevant for the selection of a tandem bearing. We can provide gearbox manufacturers with a tandem bearing

data sheet so that all relevant data can be recorded precisely. This allows

the optimum bearing solution to be recommended.


4.Mounting 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 , which in turn will result in increased strain on the components. Since tandem bearings are thrust bearings that are not capable of supporting radial loads, it is advisable to provide sufficient radial support. One way to do this is to use needle roller bearings. This will allow potential shaft deflection and associated frictional losses to be reduced, especially in the case of continuous shafts where pinion and tandem bearing are on the same shaft and not separated by a gear coupling.


5. Minimum Load for Tandem Bearings

The minimum load or preload for tandem bearings has been defined as one percent of the dynamic load rating C. Two issues are important when dealing with the question of minimum load. The first pertains to the kinematics of the bearing and the other is the deflection behavior.


5.1 Kinematics

Thrust bearings should never run without a certain minimum load. This load prevents rolling bearing slip and the resulting surface damage in the case of acceleration or hesitation. The minimum load F a min for thrust cylindrical roller bearings can be calculated using the formulas given in .


5.2 Deflection Behavior


Larger deflection differences can lead to the contact of screw flanks or to premature screw wear. For tandem bearings the spring curve is relatively flat for low loads and does not become linear until a certain load ratio C/P is reached. The reason for this is that tandem bearings are “softer” than single row thrust cylindrical bearings, whose entire spring curve is in the linear range. To be able to record the deflection path accurately and achieve suitable operating conditions, tandem bearing operation should be within the linear range of their spring curves. Put another way, they should have sufficient preload.

Depending on the size, the preload can be applied in different ways. In general, a compression spring is suitable for small to medium preload forces . For larger tandem bearings, disk springs are preferred for the application ofpreload forces .


6. Service Life

As is the case for thrust cylindrical roller bearings, the service life of tandem bearings is calculated using the formulas provided. If required, the extended rating life L naa can also be calculated. The oil temperaturerequired for this calculation can be taken from the oil outlet since experience has shown that lubricant flowing through the bearing is between 5 °C and15 °C warmer than the inlet temperature.


7. Lubrication and Cooling

In general, circulating oil lubrication should be used to lubricate tandem bearings.The oil is always fed from the back, which means that the lubricant flows through the bearing against the direction of the axial force. The gearbox housing at the end of the tandem bearing must be closed so that the required amount of oil is available. Although the rotating thrust cylindrical roller and cage assemblies promote oil flow, an additional feed pump must be used in order to achieve a sufficient oil exchange in the bearing.

The required amount of oil is calculated using the formulas given . When calculating the speed dependent frictional torque caused by fluid friction, the number of rows must be considered.


8. Summary

Tandem bearings provide an optimum solution for applications with the

following requirements:

– Small radial design envelope

– Support of high axial loads

– High speeds

– Long service life

Due to the high operational safety, it would be hard to imagine modern extruder gearboxes without this reliable machine element.

Quality 8 stage cylindrical roller thrust bearing for sale
Send your message to this supplier
 
*From:
*To: LUOYANG BAOCHEN MACHINERY TECHNOLOGY CO., LTD
*Subject:
*Message:
Characters Remaining: (0/3000)
 
You may also be interested in :
Inquiry Cart 0
  • Haven't found right suppliers
  • Our buyer assistants can help you find the most suitable, 100% reliable suppliers from China.
  • And this service is free of charge.
  • we have buyer assistants who speak English, French, Spanish......and we are ready to help you anytime!
  • Submit Buying Request
    Contact Us Quickly