A Process/Machine coupling approach: Application to Robotized Incremental Sheet Forming

International audienceIn this paper, a Process/Machine coupling approach applied to Robotized Incremental Sheet Forming (RISF) is presented. This approach consists in coupling a Finite Element Analysis (FEA) of the process with an elastic modelling of the robot structure to improve the geometrical accuracy of the formed part. The FEA, assuming a rigid machine, is used to evaluate the forces at the interface between the tool and the sheet during the forming stage. These forces are used as input data for the elastic model, to predict and correct the tool path deviations. In order to make the tool path correction more effective, the weight of three numerical and material parameters of the FEA on the predicted forces is investigated. Finally, the proposed method is validated by the comparison of the numerical and experimental tool paths and geometries obtained with or without correction of the tool path

Off-line compensation of the tool path deviations on robotic machining : Application to incremental sheet forming

International audienceIn this paper, a coupling methodology is involved and improved to correct the tool path deviations induced by the compliance of industrial robots during an incremental sheet forming task. For that purpose, a robust and systematic method is first proposed to derive the elastic model of their structure and an efficient FE simulation of the process is then used to predict accurately the forming forces. Their values are then defined as the inputs of the proposed elastic model to calculate the robot TCP pose errors induced by the elastic deformations. This avoid thus a first step of measurement of the forces required to form a test part with a stiff machine. An intensive experimental investigation is performed by forming a classical frustum cone and a non-symetrical twisted pyramid. It validates the robustness of both the FE analysis and the proposed elastic modeling allowing the final geometry of the formed parts to converge towards their nominal specifications in a context of prototyping applications

Closed-loop control of product properties in metal forming

Metal forming processes operate in conditions of uncertainty due to parameter variation and imperfect understanding. This uncertainty leads to a degradation of product properties from customer specifications, which can be reduced by the use of closed-loop control. A framework of analysis is presented for understanding closed-loop control in metal forming, allowing an assessment of current and future developments in actuators, sensors and models. This leads to a survey of current and emerging applications across a broad spectrum of metal forming processes, and a discussion of likely developments.Engineering and Physical Sciences Research Council (Grant ID: EP/K018108/1)This is the final version of the article. It first appeared from Elsevier via https://doi.org/10.1016/j.cirp.2016.06.00

Double-sided incremental forming: a review

Incremental sheet forming (ISF) or single point incremental forming (SPIF) processes have been developed rapidly in the past three decades. Its high flexibility and easy operability have a significant appeal for industrial applications and substantial progress has been made in fundamental understanding and demonstration of practical implementation. However, there are a number of obstacles including achievable accuracy and instability in material deformation which are considered as a main contributing factor for preventing the ISF process to be widely used in industry. As a variant of the general ISF process, Double-Sided Incremental Forming (DSIF) uses an additional supporting tool in the opposite side of the workpiece, maintains the flexibility and at the same time improves the material deformation stability and reduces material thinning. In recent years, there has been increased research interest in looking into DSIF specific material deformation mechanisms and DISF investigation. This paper aims to provide a technical review of the DSIF process as benchmarked with SPIF. It starts with a brief overview of the current state of the art of both SPIF and DSIF. This is followed by a comparative study between SPIF and DSIF with the key research challenges identified. This leads to a recommendation of key research challenges for DSIF focused research

Thickness control in a new flexible hybrid incremental sheet forming process

Incremental sheet forming is a cost-effective process for rapid manufacturing of sheet metal products. However, incremental sheet forming also has some limitations such as severe sheet thinning and long processing time. These limitations hamper the forming part quality and production efficiency, thus restricting the incremental sheet forming application in industrial practice. To overcome the problem of sheet thinning, a variety of processes, such as multi-step incremental sheet forming, have been proposed to improve the material flow and thickness distribution. In this work, a new process has been developed by introducing multi-point forming as preforming step before conducting incremental sheet forming processing. Employing an established hybrid sheet forming system and the corresponding thickness prediction model, the preform shape can be optimized by employing a two-step optimization approach to improve the sheet thickness distribution. In total, two case study examples, including a hemisphere part and an aerospace cowling part, are fabricated using the developed hybrid flexible process in this study. The experimental results show that the hybrid flexible forming process with the optimal preform design could achieve sheet parts with more uniform thickness distribution and reduced forming time

Industry 4.0 and New Paradigms in the Field of Metal Forming

Over the last few year, the metalworking sector has been undergoing rapid and radical transformations driven by global competition and the revision of the production focus that is being moved from mass customization to mass individualization. A results of this is introduction of new manufacturing strategies such as Industry 4.0, a concept that combines cyber-physical systems and promote communication and connectivity. Therefore, this concept changes not only the face of the manufacturing systems but also causes transformation of existing business models and the society as a whole. This paper deals with the recent trends and paradigms in the field of metal forming, resulting from the concept of Industry 4.0 and the modern market challenges. The maim attention is paid on the flexibility of manufacturing systems and recent developments in design of smart forming tools

Elasto-geometrical modeling and calibration of robot manipulators: Application to machining and forming applications

International audienceThis paper proposes an original elasto-geometrical calibration method to improve the static pose accuracy of industrial robots involved in machining, forming or assembly applications. Two approaches are presented respectively based on an analytical parametric modeling and a Takagi-Sugeno fuzzy inference system. These are described and then discussed. This allows to list the main drawbacks and advantages of each of them with respect to the task and the user requirements. The Fuzzy Logic model is used in a model-based compensation scheme to increase significantly the robot static pose accuracy in a context of incremental forming application. Experimental results show the efficiency of the Fuzzy Logic model while minimizing development and computational resources