Measurement of pressure distribution in a deformable nip of counter-rotating rolls

Abstract

This paper describes a technique for measuring the pressure distribution of fluids flowing through a deformable nip of rolls counter-rotating at high speed. The technique is based on the use of a high sensitivity piezoelectric transducer mounted on the rigid roll of a laboratory film coater developed for the hydrodynamic characterization of roll coating flows. The pressure data are continuously recorded in a PC through a data acquisition card having a high-speed recording capacity, so that the experiments can be performed in conditions quite similar to those encountered in the coating industry. The pressure distribution of Newtonian fluids with different roll speeds and applied load between the rolls are reported and discussed. The results obtained are in good agreement with the data reported in the literature.

Mechanical Response of Paperboard in Rapid Compression – The Rapid ZD-Tester, A Measurement Technique

“…Two methods have been used to compare the material behaviour in out-ofplane compression: the rapid ZD-tester [28], [29] and a conventional universal testing machine (UTM). 1 All measurements were performed at standard climate (23 °C and 50% RH) after conditioning the samples for a minimum of 24 hours. In both methods, the sample is resting flat on a surface larger than the measurement probe.…”

“…A modern flexographic printing process can run with a web-speed of several hundreds of meters per minute, meaning that the substrate is only in contact with the print nip for a few milliseconds during ink transfer. The pressure profile of a soft nip has been shown both experimentally [1]- [5] and numerically [6]- [9]. The impression or pressure in a flexographic print nip is very soft in comparison to other contact printing methods.…”

Lubricated rolling over a pool

“…(2021), wherein a solid object is held aloft by a vertical moving belt coated with a thin layer of viscous fluid. The splitting of the film at the downstream meniscus also features in a great many other coating problems (Greener & Middleman 1975; Benkreira, Edwards & Wilkinson 1981; Coyle, Macosko & Scriven 1986; Decré, Gailly & Buchlin 1995; Weinstein & Ruschak 2004; Ascanio & Ruiz 2006; Becerra et al. 2007).…”

“…The lubricated rolling process illustrated in figure 1 is similar to the levitation problems considered by Eggers, Kerswell & Mullin (2013), Mullin, Ockendon & Ockendon (2020) and Dalwadi et al (2021), wherein a solid object is held aloft by a vertical moving belt coated with a thin layer of viscous fluid. The splitting of the film at the downstream meniscus also features in a great many other coating problems (Greener & Middleman 1975;Benkreira, Edwards & Wilkinson 1981;Coyle, Macosko & Scriven 1986;Decré, Gailly & Buchlin 1995;Weinstein & Ruschak 2004;Ascanio & Ruiz 2006;Becerra et al 2007). In particular, the associated two-dimensional flow is known to be prone to the so-called printer's instability, which generates a complicated three-dimensional filamentary structure (Pearson 1960;Pitts & Greiller 1961).…”

Textile piezoelectric sensors – melt spun bi-component poly(vinylidene fluoride) fibres with conductive cores and poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) coating as the outer electrode

“…From the shear viscometry presented in Figure 8, coating B has a significantly more Newtonian behaviour with a more steady viscosity both during the high shear forces of the coating procedure as well as during the low shear of the drying process than coating A. Coating A appears more influenced by the binder formulation and its thickener than the HEUR and could be expected to flow very well during extremely high shear, but will soon return to its high viscosity state when these forces cease (Ascanio and Ruiz 2006;Davard and Dupuis 2002;Glass and Prud'homme 1997). This could explain the distributions of the coatings from the images in Figure 7, where coating A penetrated more below the fibre bundle than coating B.…”