Process And Mechanism Of Plowing Extrusion-Cutting For Fabricating Complex Structured Metal Fins

Metal chips,as one of the pollution main sources in machining industries,usually restricted the processing efficiency and industrial benefits,and their recycling was of great significance.However,the existing chip recycling processes,such recasting,were inefficient and prone to secondary pollution,making it difficult to meet the requirements of green manufacturing.Chip forming cutting methods could directly transform the uncut metal into metal fins with specific structure,having the characteristics of direct,high efficiency and low consumption,which provided a potential solution for the recycling of metal chips.However,the existing process mainly used the constraint and cutting tools to form an extrusion channel,transforming the shear deformation into a strongly restrictive geometric boundary constraint shaping.This not only caused a difficult cutting process but also limited the metal fin structures due to the simple tool structure,leading to a low application value of metal fins.Based on the way of “shaping first-cutting later”,this paper proposed a new process for fabricating complex structural metal fins by plowing extrusion-cutting(PE-C).PE-C could fabricate metal fins with complex structures by completely releasing the shear deformation zone,which reduced the cutting difficulty and enhanced the application value of metal fins.As a new technology for chip conversion utilization,its process characteristics,forming properties,and forming mechanism were still unclear,and relevant research was needed.To address these issues,based on the PE-C’s principle,experimental results,and forming characteristics,this paper conducted a comparative and systematic study on the forming mechanism of PE-C.Several valuable research results were obtained:Based on the proposed idea,the combined tool was designed,and the experimental platform for fabricating complex structural metal fins by PE-C was also built.According to the PE-C’s forming principle,the key processing parameters affecting the forming results were selected,and the PE-C experiments were systematically carried out.Various complex structural metal fins such as grooved,dorsal fin-like,and wavy fins were successfully fabricated.According to the forming characteristics of metal fins fabricated by PE-C,the critical conditions and parameter ranges of different structural fins were summarized.And,the controllable processing and adjustment of fins’ structural type and geometric size were realized.To study the forming process and mechanism of grooved fins,a finite element model with thermal-force coupling was established.The material deformation process of grooved fins was analyzed in detail,and its material flow mechanism was also clarified.The changes of internal stress,strain,temperature of metal fins in different initial forming processes were characterized to improve the understanding of the parameters’ influence.By using the material velocity distribution and point tracking method,the lateral flow of workpiece material during the stable forming process was explained,and the mathematical relationship among fin height,fin width and bottom thickness of grooved fins was revealed.These results will provide a theoretical guidance for preparing grooved metal fins.According to the structural morphology of the key forming process,an in-depth analysis of the forming mechanism of dorsal fin-like fins was carried out,and a geometric model containing the morphological dimensions and distribution patterns was established.The geometric model was used to analyze the influence of key processing parameters on the size and distribution pattern of the dorsal fin-like fins.The geometric model was validated by PE-C experiments,and the experimental results were in accordance with the model predictions,proving the accuracy of the geometric model.Based on the forming characteristics of wavy fins,its forming mechanism was clarified.According to the characteristic of "velocity difference",a sinusoidal geometric model was developed to describe the relationship between key processing parameters and the structural morphologies of wavy fins.The geometric model successfully predicted the variation of wavy fin dimensions with key processing parameters.Such results provided a reference basis for the subsequent optimization of the PE-C process.A new idea was proposed to break through the forming capability limitation of the PE-C process.The new PE-C used the pre-defined cracks during the “upper surface shaping” process to reduce the “serrated” forming barriers,and enhanced the shear deformation in the first deformation zone to realize the fin structural transformation from the continuous grooved structure to pin arrays,which greatly improved the forming capability of PE-C process.The above work had achieved the research purpose of transforming the uncut metal into complex structural fins by PE-C.Meanwhile,the above work had also revealed the forming mechanism for fabricating different structural metal fins by PE-C.These results will provide a solid foundation for the further development of PE-C process in the field of metal chip recycling.