Abstract
Roll forming is a continuous process in which a moving metal sheet passes through numerous pairs of opposing forming rolls. The shafts of the roll forming mill are equipped with these rolls and must be set up and aligned to achieve the required final profile of the sheet. The practically relevant task of predicting the profile geometry of this incremental rolling process with varying characteristics of the metal sheet entering the mill requires an accurate description of the stiffness behavior of the shaft with rolls, which is the most compliant part of the roll forming mill. In this paper, the measured force-deflection characteristic of the shaft without rolls is compared with predictions of various theoretical models, followed by the adoption of the shear deformable beam model of the shaft with nonlinear elastic supports in the bearings. The coefficients of the cubic stiffness characteristics of the rotational springs as well as the effective length between the supports are identified based on the experimental data for the deflections, measured along the shaft for various loading levels. The theoretical predictions are obtained via the nonlinear finite element model of the shaft. The model thus provided shows high accuracy compared with the measurements. The paper’s results serve as a foundation for models to predict the stiffness of shafts with rolls.
Highlights
In roll forming, two opposing shafts with rolls, which are usually different for each forming pass, carry out the bending and determine the shape of the deformed profile [5]
This paper investigates the stiffness behavior of the shaft without rolls and develops suitable shear deformable beam models
This paper investigates the stiffness behavior of the shafts and the forming stands of a standard mill
Summary
In roll forming, two opposing shafts with rolls, which are usually different for each forming pass, carry out the bending and determine the shape of the deformed profile [5]. Understanding and being able to describe the stiffness behavior of the shafts with equipped rolls, in combination with prior knowledge of the emerging forming forces, would lead to a reduction of the set-up time, because the necessary infeeding of the shafts against each other can be predicted in advance. Abeyrathna et al [1] take the stiffness of the tool into account by using one linear spring for each upper rollset This means that the upper rolls of each forming pass have one degree of freedom in the vertical direction. The force level of the numerical simulation is a few times higher than the force level in the experiments He uses a simple linear spring to account for the stiffness of the tool. To the beam model, a 3D continuum FEM model in ANSYS was set up in order to gain a deeper understand of the occurring nonlinear effects
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