Process And Mechanism Of Rolling-Cutting Forming Method To Produce 3-D Fins With Complex Surface Topography

After entering the 21 st century,thanks to the extensive exploitation and use of fossil energy,human society has made rapid development and progress.However,the massive exploitation of fossil energy has also caused lots of problems such as energy shortages and environmental pollution.Fin technology is an energy-saving technology that can greatly improve energy efficiency.It is widely used in petrochemical industry,waste heat recovery,air conditioning and refrigeration,nuclear energy,aerospace,electronic cooling systems and other industries.In this paper,a new method is proposed to produce 3-D fins,namely rolling-cutting forming method.The feasibility of the method is investigated by experiments and simulations.This paper mainly includes the following aspects:(1)The rolling-cutting combined tool is designed and the forming process of the process is analyzed.The process consists of rolling process and cutting process.In the rolling process,the grooved roller rolls the transition surface of the workpiece to form a micro-groove structures.In the cutting process,the micro grooved structures with a thin bottom are cut from the workpiece by the cutting tool.At the same time,under the action of cutting deformation,the micro grooved structures are swollen and magnified.And finally the 3-D fins with abundant surface structures are formed.(2)The finite element model of the process is established using DEFORM-3D.The effects of various processing parameters on the effective stress,effective strain rate,cutting temperature and main cutting force of the processs are analyzed.(3)The forming mechanism of the process is analyzed in detail.The fin is mainly composed of the primary structure,the composite structures and the micro structures.The primary structure is inverted parabolic.The composite structures are periodically distributed on the top of the fins,which is composed of a large number of irregular rectangular protrusions.The micro structures are mainly distributed at the bottom of the fins and consists of a large number of linear structures.(4)The influences of various processing parameters on the fins size,hardness and corrosion performance are investigated.The experimental results show that as the tool rake angle decreases,the roll depth increases,the feed rate increases,and the depth of cut decreases,the fins height becomes higher and higher.The hardness of the fins is significantly higher than the hardness of the base material,indicating that the work hardening phenomenon occurs during the processing.The electrochemical experiment results of the fins show that the Nyquist plot of the fins in the 0.5 mol/L HCl solution are similar to the Nyquist plot in a 0.5 mol/L NaCl solution.The fins have little difference in corrosion resistance between the two solutions.And the smaller the rake angle,the stronger the corrosion resistance of the fins.