Mathematical Modelling and Simulation of Hard and Soft NIP Calenders used in Textile Industry

Abstract

Calendering is mechanical finishing process used in many industries such as polymer, paper, leather, printing and textile, implemented at the final stage when thin sheet of material is exposed to combine effect of moisture, heat and pressure between two or more rotating rolls (Nips) of same or different composition pressed against each other. In simple words, it is the high speed ironing process that primarily imparts luster. These rolls may be hard or soft, heated at different temperatures and vary in number from $3$ to $11$ depending upon the type of calender. newlineIn dynamic process of calendering, it is extremely difficult to evaluate the interaction of design and process parameters such as load applied, bulk modulus, speed and radius of rolls, number of nips, temperature of the rolls and fabric temperature under local external and internal conditions. Thus there is need of development of various mathematical models like models for nip mechanics, steady and unsteady state heat transfer models for complete analysis of the problem. The forecast investigation aims at identifying the relative effect of each parameter on the quality of fabric in different types of calenders such as machine calender, soft calender, temperature gradient calender used in textile industry. newlineIn this thesis, a comprehensive description of finishing process, mathematical modelling and simulation of nip mechanics and heat transfer in calendering process has been done. Methodology of systematic investigation for simulation of calendering models, namely models for nip mechanics and conduction heat transfer under different initial and boundary conditions has been developed. The above objectives are achieved with the help of MATLAB software. newlineThe nip mechanics model developed is generalized model which can overcome the difficulties poised by the models of Hertz and Meijers. The nip mechanics model for machine calender (NMMM) and nip mechanics model for rolling calender (NMMR) developed are extension of Hertz and modification of Meijers which can be