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Double-mode drawing pipe technology without mandrel
- Jun 12, 2018 -

Non-mandrel single mode drawing pipe due to uneven distribution of deformation, after pulling the pipe will produce burst phenomenon. Non-Mandrel dual-mode drawing pipe, using the principle of reverse tension drawing, that is, when the first mold pulling force on the second mold of the metal forming a reverse pull, therefore, the axial tensile stress in the second die increases, the radial compressive stress decreases, thus the uneven distribution of deformation is improved, the harmful residual stress is reduced, and the wall thickness is further controlled. Dual-mode drawing pipe has long been used long mandrel, short mandrel, floating mandrel and no mandrel, such as a variety of extubation mode. It strengthens the cold drawing process, improves the product quality and lowers the cost. However, for a long time, the two-mode drawing system has been lacking in the process theory, so the advantages of the double mode drawing are not fully exerted, which affects its application. For this reason, the production experiment and technical discussion of double mode drawing system in 1984, the influence of double mode drawing pipe on the wall thickness of pipe was studied, the influence of double mode on the deformation inhomogeneity of pipe was investigated, the effect of double mode on pulling force and power consumption was analyzed, and the new combined external model of double mode drawing was made. The results show that the two-mode drawing and single mode comparison of coreless rods has the following advantages: increase the number of road deformation, productivity increased by about 70%, reduce the deformation of the steel tube uneven, improve the plasticity of the metal, reduce residual stress, reduce the bending of the steel tube, the required deformation is small, can save power consumption 10%~15% The tube wall is not thickened and the pipe head loss is reduced.

The stress state of single mode and double mode drawn stainless steel pipe was analyzed by using coreless rod double mode drawing stainless steel tube In 1992, and the wall thickness of the tube was measured, and the conclusion was further proved that the double mode drawing wall thickness change was smaller than that of single-mode drawing and reducing wall.