|
(Sing point incremental forming, SPIF) is a fast flexible forming sheet metal single-point incremental forming, sheet metal parts forming arbitrarily complex shapes, the mold without specific, more suitable for aerospace, automotive, and small quantities of civilian areas, diversity, the complexity of the production of the plate member. Based on the finite element numerical simulation and experimental methods, mainly for sheet metal forming mechanism, forming limit, forming defects, such as formability research, and get some useful conclusions follow-up study of incremental forming technology and its common promote the application of great significance. This paper first describes the numerical simulation of incremental forming processes and methods. Introduces a single point incremental forming dieless forming processes, mechanics model and numerical simulation parameters set; elaborate numerical simulation trajectory generation, especially ways to avoid the bottom of the workpiece distortion analog track forward and inverse white occur. Next, the progressive shaping mechanism. Analyzed the the incremental forming parts of the stress-strain state and its thickness distribution law, the study showed that: in a plane stress state is forming unit; straight path when loading, deformation in plane strain state unit the loaded circular path, the deformation unit strain state tend to double pull state; workpiece thickness distribution follows the cosine rule. Again, based on the finite element numerical simulation focuses on the progressive forming limit. The application Oyane toughness rupture standards, to effectively predict the thickness 1.5mm LY12 (M) and a hard aluminum plate incremental forming limit, when the rupture of the integral value I = 4, numerical simulation and prediction of the workpiece rupture starting point and forming limit diagram with the experimental results more consistent. Incremental forming with the deformation characteristics of the \The study showed that the ratio R / t, the radius of the tool head and the thickness of the sheet. Have a great impact on incremental forming of forming limit, r / t. The value is too small, sheet local stress concentration, easily ruptured instability, reducing the forming limit; R / t. Value is too large, with the traditional ball head punch bulging similar way, forming the lower limit. Therefore, for a certain thickness of the sheet, you must choose the right size of the tool head. Finally, specific analysis of the incremental forming defects (wrinkling, rebound, indentation, and the bottom of the inner drum convex shape variation, forming micro-cracks and other) reasons, and reasonable measures.
|