Camber Profile Providing Rubber-Covered Pressure Rollers with Uniform Load Distribution

Abstract

It is very important in textile dyeing and finishing processes to make load and nip distributions uniform over the full length of pressure rollers in contact. There is a wide variety of sophisticated methods which provide pressure rollers with uniform load distribution. Among them, a cambered roller has been widely used with success in compensating for roller deflection by a distributed thickness of roller covering. In this paper, a theoretical method for determining a surface camber which provides pressure rollers with a rigorously uniform load distribution is introduced and discussed. It is developed by using fundamental equations, previously derived by the authors, describing both two-dimensional load-deflection behavior of the covering and one-dimensional flexural behavior of the pressure rollers.The following is a summary of conclusions obtained by the analytical investigations : (1) A camber profile is derived theoretically which provides a pair of a rubber-covered roller and a steel roller or a pair of identical rubber-covered rollers with a uniform pressure distribution. This camber profile is expressed as a product of the amount of the deflection of the rollers due to a design load distributed uniformly and a factor determined by the strain of the covering under the design load. The thickness distribution of the covering can be easily calculated using structural parameters of the rollers. (2) The camber profile of the covering thus determined is independent of the thickness of the covering except an extremely thin covering. Hence, the thickness of the covering can be arbitrarily chosen by considering other requirements such as two-dimensional compressive behavior of the coverings. (3) A theoretical camber profile is uniquely determined for a design load of a mangle. Therefore, a uniform load distribution can not be expected when the mangle works under other loads than the design load. If the load during operation will vary within a certain range, it is preferable to design the rollers using a slightly smaller value of design load than the central value between the maximum and the minimum loads of operating conditions.