Digital printing machines (corrugated board)
Vibration insulation of a Bobst Digital Printing Machine
An expert and manufacturing company for packaging solutions in solid and corrugated board all over Europe planned installing a new printing system of the type Bobst Geneva 2. Close to the installation site of the printing system is standing a mastercut-system with a punching unit. The area of the punching unit is built with a cellar. Noticeable vibrations were the result of the operation of the mastercut, especially on the area with cellar. In order to reduce the vibration transmission to the new printing system Bobst Geneva 2 it was planned installing the new printing system on a sprung foundation (length approx. 20 m) of isoloc. Isoloc was engaged with vibration measurings in the run-up to the construction measures to record and assess the occurring vibrations and to select the appropriate vibration insulation elements of isoloc. As expected, the strongest vibrations arise close to the punching unit of the mastercut-system in the area with cellar.
FEM-calculation of the foundation block. Safeguarding of bending natural frequency requirement of 25 Hz.
The pre-dimensioning of the architect and structural engineer resulted in a thickness of 0.50 m of the foundation block which had to be installed elastically on the vibration insulation packs of isoloc.
Due to the results of the vibration measurings by isoloc at the installation site and to the recommended highly elastic vibration insulation packs IPK66, this thickness of the foundation block was not sufficient according to a first assessment. The requirement was a bending natural frequency of >= 25 Hz!
Engineers of isoloc determined by various FEM-calculations (modal analyses) a thickness of at least 1.5 m for the foundation block with a length of 20 m, i.e. the triple amount of the initial "design".
Only thus the required natural frequency > 25 Hz for the foundation inclusive machine could be achieved and safeguarded.
Vibration insulation by a sprung foundation
image 1: reinforcement of the foundation installed on isoloc
image 2: elastically mounted foundation block, L= 20 m
image 3: Bobst Printing Machine on isoloc Sprung Foundation
image 4: concrete plate with machine, FEM-structure
image 5: concrete plate without machine, thickness 1.5m, f0 = 31.7 Hz
image 6: concrete plate with machine, f0 = 110.2 Hz