FOCUS ON MATERIALS
The components that have been tacked manually are welded together using a welding robot .
are then determined and set at the level of the natural frequencies . The modal hammer generates multiple force pulses by striking the component briefly and forcefully .
During vibratory stress relief , two vibration transducers measure and monitor the acceleration triggered in the component by the impulse applied . A triaxial accelerometer measures the acceleration of the workpiece in the X , Y and Z axes . A monoaxial sensor measures how much acceleration is being applied at the point on the plate furthest away from the motor . The stress relief process takes place in five cycles of up to ten frequencies each , in which the modal hammer determines the natural frequencies of the component . Once the frequency of the component changes , the automatic control system uses modal analysis to adjust the imbalance and rotational speed accordingly . A frequency band is used to determine the respective stress relief status of the
During vibratory stress relief , two vibration transducers measure and monitor the acceleration triggered in the component by the impulse applied
A wide milling path was machined on the top of the welding seam to mill off weld material and the heat-affected zone completely . component . A final measurement is taken once the five cycles have been completed . All the frequencies are recorded in a log and the stress relief status is depicted in a diagram . For large components , which are the order of the day at Jebens , the motor must be moved several times to ensure that the entire component can be relieved of stress . All the processing frequencies are determined , processed and documented automatically ( alphanumerically and graphically ) in the vibration log .
According to VSR Industrietechnik , modal analysis has provided scientifically valid evidence that the residual stresses in the component have been reduced to such an extent that distortion in the component can be ruled out . Crack formation in components is also eliminated due to the low vibration amplitude . The Duisburg-based company has sold around 150 vibratory stress relief systems to date .
Industrial companies such as ThyssenKrupp , AUDI , Ford , Caterpillar , Liebherr and Sennebogen have been using this process in their own production for decades or have prescribed its use to their suppliers . At Jebens , many demanding industrial customers also rely on vibratory stress relief for components for press brakes with part weights of up to
Three measuring tracks were milled on the back of the plates and 2mm was added in during each milling run .
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