Thermal Flow Field Analysis and Structural Optimisation of The Stretching Oven for PP Strapping Tape

Abstract

As the core preheating equipment in polypropylene (PP) strapping tape production, the stretching oven’s performance is critically influenced by the uniformity of its internal thermal flow field, which directly determines the molecular chain orientation of the tape blank and the final product’s mechanical properties. Addressing prevalent operational issues such as non-uniform temperature distribution, localized eddy currents causing excessive temperature gradients across the tape blank, and significant fluctuations in final product thickness, this study focuses on a double-belt PP strapping tape stretching oven. A three-dimensional geometric model was constructed using SolidWorks, and computational fluid dynamics (CFD) simulations were performed with its Flow Simulation module. The analysis employed the standard k-ε turbulence model to investigate the distributions of temperature and velocity fields within the oven systematically. The reliability of the numerical model was validated through experiments involving platinum resistance thermometry and hot-wire anemometry, with a maximum relative error of ≤10%. Four distinct structural optimization schemes were subsequently designed and compared. Results indicated that the original oven configuration yielded a maximum temperature difference of 1.5 °C and a relative RMS deviation of velocity of 0.54 in the strapping tape channel, corresponding to product width fluctuations of ± 0.3 mm. Among the proposed modifications, Optimization Scheme 1, which incorporated curved spacers within the air ducts, demonstrated the most significant improvement. This design reduced the maximum temperature difference to 1.0 °C and decreased the velocity’s relative RMS deviation to 0.25—a reduction of 53.7%. Consequently, the product width fluctuation range was narrowed to ± 0.2 mm, representing a 33.3% improvement in dimensional consistency. This research provides a theoretical foundation and practical guidance for enhancing the performance of strapping tape stretching ovens.