Operating histories show that machines and systems, despite careful design and production, are affected by external factors that can impair their functionality or cause damage, defects, faults, weak points, disruptions and even failure. When damage occurs due to mechanical loads, it also becomes necessary to consider the dimensioning of the drive technology in use.
Initially, of course, operating histories provide some orientation. If a machine does not reach its intended power out put and/or achieve the desired qualities, its drive systems may be intended for smaller loads or other performance
problems may exist in the system. If damage actually occurs, the damage patterns contain valuable information.
Forced fractures, for example, are often caused by malfunctions, seizures or overloads. Fatigue fractures and cracks can be caused by impermissible load vibrations or disturbing vibrations. Typical fatigue fractures or forced fractures in a universal joint shaft are shown in Figure 1.
In the construction of machines and plants, torques and bending moments are important mechanical load quantities for rotating components, and they allow the reduction of costs (Figure 2). Load measurements consist of a static (temporally constant) and a dynamic part (cyclic or fluctuating load). In the case of regular load variations, the amplitude and frequencies of the dynamic aspect are of interest.
An additional load analysis can be applied to more quickly analyze and communicate the causes of atypical damage, as well as to reduce impermissible dynamic loads through knowledge, experience and/or increased precision. Reduced dynamic loads mean that machine components that are subject to complex loads during rolling, friction and impact processes will “run” better and “reward” the owner with a longer service life.
Figure 3 illustrates this for a large mill drive system before and after an optimization was implemented. The minimum,
mean and maximum torque values are shown in kNm, each recorded at an interval of 5 minutes. Reduced load variations can be detected starting on 03/27.