Development of Computational Models for Coiling Process with the Belt Wrapper

This study introduces coiling mechanism with the belt wrapper to understand a force equilibrium for successful coiling. By establishing a finite element (FE) model, strips were coiled 2 to 3 rotations by the belt wrapper on the sleeve without coiling tension T, then T was applied to the opposite side of the strips near the pinch roller, and the belt wrapper was removed from the strip coil at the same time. Additionally, analytical model corresponding to FE model was defined by thick and thin cylinder theorems to quantize coiling mechanisms. Especially elasticity of the belt wrapper E [N/m2], coiling tension T [N/m2], and friction coefficient μ were checked on how these variables affect each other, were converted into pressure P [N/m2], and P were used to calculate when the strip coil come untied. For instance, the strip coil came untied when E was lower than 1 × 109 N/m2 corresponding to $$ \left( {\frac{{{\text{Pressure}}\; {\text{on}}\; {\text{outmost}}\; {\text{of the belt wrapper}}\; P_{\text{o,belt}} }}{{{\text{Pressure}}\; {\text{on}}\; {\text{innermost}}\; {\text{of the sleeve}}\; P_{\text{i,sleeve}} }} = 0.877} \right) $$ . Lastly, radial stress on the outmost of the sleeve σ r,o,sleeve [N/m2] according to E were compared to the previous coiling method with the grooved joint to see how these methods are different. Based on these results, this paper suggests coiling criteria to avoid coiling failure of slip of the strip coil.