Plastic Folding of Bar Stocks of Round and Barrel-Shaped Sections

Research has been carried out on the process of plastic folding of bar stocks with round and barrel-shaped cross-sections. The dependence of the movement of the movable tool on the bending angle has been established. The force parameters of the deformation process and the stress-strain state in the bending workpiece are determined based on the results of finite element modeling of plastic bending.

Plastic Bending at Large Strain: A Review

Finite plastic bending attracts researchers’ attention due to its importance for identifying material properties and frequent occurrence in sheet metal forming processes. The present review contains theoretical and experimental parts. The theoretical part is restricted to analytic and semi-analytic solutions for pure bending and bending under tension. The experimental part mainly focuses on four-point bending, though other bending tests and processes are also outlined.

Plastically Bendable Crystals of Flufenamic Acid Form III

Bendable organic crystal is a burgeoning research field due to interesting phenomenon and broad application prospects. Here we report a plastic bendable pharmaceutical crystal, flufenamic acid (FFA) form Ⅲ crystal. The crystal exhibits plastic bending when the force is applied on (100) face. The column-like structure and the slip planes among them are the basic features responsible for the exceptional plasticity. The spatially resolved atomic-level studies via X-ray diffraction and micro-Raman reveal the structural perturbations in FFA crystal after bending, illustrating that the packing in each “column” is also critical for the plastic bending, which contributes to the exploration of plastic bending mechanism and inspires the design of flexible organic crystal materials.

Development of a method and equipment for testing materials for alternating bending during piercing in screw rolling mills

Hot-rolled pipe production is complicated process of metal treatment by pressure and as a rule it has three operations of form charging: piercing, plugging, calibration or reduction. Each of them is characterized by complex schemes of stress-deformed state which promotes either formation or detection of various defects. Hot billet piercing at screw piercing rolling mill is widely used for pipe production for its high output and getting the shells of long length. But this operation of form charging of the metal is realized under the conditions of complicated stress-deformed state with cyclic alternating bending of all metal layers. Defects appearing on the outside surface of the shell such as captures and cracks is caused by plastic bending of shell wall, which is followed by alternating stress and deformation at the inlet and outlet cone of deformation zone in consequence of four times plastic bending of the wall. Shell wall is influenced by compression stress of the working rolls and guides. The less favorable scheme of stress state with tensile stress arises on the shell surface between the rolls and the guide. And as a results it generates and increases the defects on the outside surface. Theoretical and experimental research of deformation and speed conditions of billet piercing process for screw piercing rolling mill is presented in the work. Statistic data of production mills which operate in TRA 50-200 and TRA 159-426 lines were used for the research. All the calculations were done with use of applied software and test machine of original design with crank and connecting rod mechanism was constructed. The machine carries out the process of alternating plastic bending which is in maximum close to the conditions taking place in deformation zone of screw piercing rolling mill. Definition of rational configuration of sample shape was determined. Process plasticity of the metal of hot samples was analyzed as well. The samples were made from hot-rolled bars of different steel grades.