Pulp Paper & Logistics
HEIMBA 21CH ANDRITZ
Image 2: TASK expert picks up data with the ‘multiplexer’
equipped with contact points that are connected to the membranes. For each customer, a specific measuring file, already created with the aid of a calibrating station, is installed on each of these measuring membranes. The computer records all raw data which can be read immediately on-site.
This allows Heimbach to
show force and nip area to the customer on the day of visit. Precise nip lengths are measured later in the office using the specialist software. This is a crucial processing step and experience in nip profile measurement plays a major role here.
Special membranes for a special service However, the most important role in this on-site measurement is played by the sensor membranes, which are prepared with a special fluid. This fluid inside the membrane consists of several polymers that change their electrical resistance depending on the force applied to them. The computer software in turn records and interprets this resistance. Obviously, the measuring membranes must be able to withstand great pressure but at the same time register the minutest differences; so they must be both robust and sensitive.
During application the
following must always be observed: The membranes must be placed exactly between the two rolls to ensure that precise nip measurements are recorded. When everything is prepared the press rolls are brought together and pressure is thus exerted on the membranes. The TASK expert went on to pick up the data from all 14 membranes (Image 2). The results are shown in the original image (Figure 2).
Straight facts Figure 2 represents the nip lengths, which were remarkably uniform across the entire machine width. The values from the 14 membranes are
4
Figure 1: CD Moisture profile from three different press felts
Figure 2: A good thing – uniform nip lengths November/December 2017
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