Design and experimental of veneer curling roll forming platform for wooden scrimber

Wood has been one of the important renewable resources with environmental friendliness and recyclability among raw materials. The rotary-cut veneer has been processed from low-quality wood, such as fast-growing poplar. The discontinuous flat-pressing has been commonly used to produce the plywood or the cover material for eco-boards. The low-quality wooden veneers were then reconstituted to realize the high-value utilization. The continuously restructured timber moulding is conducive to the production efficiency and automation level in sustainable timber development. This study aims to design the forming platform of veneer curling and roller pressing for the wooden reconstituted materials. The preparation of wooden-based pipelines was taken as an example. The process parameters were optimized and verified for the performance of the platform. The entire mechanical structure was designed for the veneer curling and roller pressing forming platform. Detailed design and theoretical calculations were performed for the key components, such as the roller pressing, the wood roll shaft braking anti-slip, and the glue application pressing device. The tests were also performed on the physical prototype to validate the rationality and applicability of these components. A 10.16 cm wooden pipe was prepared with the core shaft rotation speed, veneer thickness, and pressure as the test factors, while the ring stiffness and axial compression strength of the wooden-based pipeline as the test indexes. Regression equations between factors and test indexes were established using the Box-Benhnken design. The optimal combination of parameters was then obtained to prepare the wood pipes: the mandrel speed of 16 r/min, veneer thickness of 2.15 mm, and pressure of 293 N. The predicted ring stiffness of the wooden-based pipeline was 26 016.6 N/m² in this case, and the axial compression strength was 23.11 MPa. Verification tests show that the error between the predicted and actual ring stiffness was 1.07%, and the error of axial compression strength was 4.46%. Furthermore, the better performance was achieved in the wooden-based pipelines with the inner diameters of 5.08,7.62,12.70 cm. Specifically, the ring stiffnesses were 43 812, 32 655, and 17 532 N/m², respectively, while, the axial compression strengths were 25.83, 24.71, and 20.17 MPa, respectively. Therefore, the forming platform can be effectively applied to prepare the wood pipes. The full utilization of low-quality materials can be realized, such as agricultural and forestry residues. The finding can provide a strong reference and technical support for the industrial application of wooden reconstituted material curling and roller pressing forming and equipment. Particularly, the wood recombinant material can take the low-quality veneer as the raw material. The adhesive and heating device can also be optimized to expand the application scope for high production efficiency.