PRESS SECTION VIBRATIONS.

Vibration occurring in the press section of paper machinery can be very difficult to isolate and resolve. This article reviews some of the tools available for trouble-shooting and discusses some of the different forms of vibration problems which can occur, with suggested remedies. Topics discussed include: vibration measuring equipment (transducers, analyzers and recorders) and how to use the information they convey; component vibrations (rolls out-of-balance or at critical speed) and the sympathetic vibrations they may set up elsewhere in the machine; structural vibrations when an entire framework vibrates, and the use of finite element analysis compared with impulse testing or speed-variation runs to determine natural frequencies; nip bounce and possible means of eliminating it; race and roller defects.