Bearings process rolls

Process rolls are commonly found in paper machines and other continuous process applications. Process rolls generate few unique vibration frequencies. In most cases, the only vibration frequencies generated are running speed and bearing rotational frequencies. 

However, rolls are highly prone to loads induced by the process. In most cases, rolls carry some form of product or a mechanism that, in turn, carries a product. For example, a simple conveyor has rolls that carry a belt, which carries product from one location to another. The primary monitoring parameters for process rolls include bearings, load distribution, and misalignment. 

By design, process rolls should be uniformly loaded across their entire bearing span (see Figure 44.13). Improper tracking and/or tension of the belt, or product carried by the rolls, will change the loading characteristics. 

The loads induced by the belt increase the pressure on the loaded bearing and decrease the pressure on the unloaded bearing. An evaluation of process rolls should include a cross-comparison of the overall vibration levels and the vibration signature of each roll s inboard and outboard bearing. 

Acceleration sensors are attached to bearings and close to roll shafts, to detect bearings at risk of failing and roll roundness abnormalities before they have a negative impact on the process. Thus bearing and roll changes can be done during the next planned shutdown of the machine, and do not cause extra... 

Screw compressors use both Babbitt and rolling-element bearings. Because of the thrust created by process instability and the normal dynamics of the two rotors, all screw compressors use heavy-duty thmst bearings. In most cases, they are located on the outboard end of the two rotors, but some designs place them on the inboard end. The actual location of the thmst bearings must be known and used as a primary measurement-point location. 

Se is concentrated in certain ore deposits, such as roll-front U complexes and Carlin-type gold deposits. Roll-front U deposits occur where U(Vl)-bearing groundwater migrates into reducing zones which precipitate both U(TV) and Se(0) or Se(-II). It may be possible to constrain Se sources and/or ore-forming processes using Se isotope variations. 

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