Multi-stage and robot assisted incremental sheet metal forming: a review of the state of art and comparison of available technologies
Incremental sheet metal forming is a recently innovated technology of achieving asymmetric sheet metal parts without using a die and through computer numerical control machine tool based path programming by inducing localized plastic deformation with a spherical ended tool. One of the major limitations of the existing method of incremental sheet metal forming is the limiting wall angle, where a wall angle of greater than about 70° is difficult to obtain. The recently proposed solution of multi-stage incremental forming can enable obtaining wall angles close to 90° but it takes longer manufacturing time and may pose problems for materials that severely strain harden. Robot-assisted incremental forming has a potential to offer an alternative solution for steel wall angle limitation but the existing work in the literature on robot-assisted incremental forming mostly focused only on the use of a standalone robotic manipulator instead of the limiting 3-axis CNC vertical machining center or a more expensive 5 or 6-axis vertical machining center. In this paper a review and comparative study of existing multi-stage incremental forming and robot-assisted incremental forming technologies in solving the limiting wall angle problem is presented.
CAx Process Chain for Two Robots Based Incremental Sheet Metal Forming
Abstract Robot based incremental sheet metal forming, also called Roboforming, is a dieless incremental forming process. It is especially suitable for rapid prototyping and manufacture of small batch sizes with low costs. This paper introduces the whole process Chain of this method, including CAD, CAM and CAE. With the use of this process chain, not only the robot programs for forming experiments, but also the simulation results of formed workpieces can be obtained. Furthermore, the CAE-results are used in the CAM-process to realize the tool path planning considering both CAD-models and many real influencing factors on the forming accuracy.
Rational Design, Synthesis and Evaluation of γ-CD-Containing Cross-Linked Polyvinyl Alcohol Hydrogel as a Prednisone Delivery Platform
This study describes the in-silico rational design, synthesis and evaluation of cross-linked polyvinyl alcohol hydrogels containing γ-cyclodextrin (γ-CDHSAs) as platforms for the sustained release of prednisone (PDN). Through in-silico studies using semi-empirical quantum mechanical calculations, the effectiveness of 20 dicarboxylic acids to generate a specific cross-linked hydrogel capable of supporting different amounts of γ-cyclodextrin (γ-CD) was evaluated. According to the interaction energies calculated with the in-silico studies, the hydrogel made from PVA cross-linked with succinic acids (SA) was shown to be the best candidate for containing γ-CD. Later, molecular dynamics simulation studies were performed in order to evaluate the intermolecular interactions between PDN and three cross-linked hydrogel formulations with different proportions of γ-CD (2.44%, 4.76% and 9.1%). These three cross-linked hydrogels were synthesized and characterized. The loading and the subsequent release of PDN from the hydrogels were investigated. The in-silico and experimental results showed that the interaction between PDN and γ-CDHSA was mainly produced with the γ-CDs linked to the hydrogels. Thus, the unique structures and properties of γ-CDHSA demonstrated an interesting multiphasic profile that could be utilized as a promising drug carrier for controlled, sustained and localized release of PDN.