ABSTRACT   Metal shearing machines are heavy equipments usually linked to low added-value due to the small amount of technological devices incorporated. However, this situation can be changed through equipment designers' creativity. Analysing some specific operations, it can be observed that some tools, when coupled to the equipment, should substantially increase the cutting process productivity and the final product quality. Regarding the thin metal plates shear process, it can be found that in the cutting final stage, the cut material weight is suspended by a small material section still requiring to be cut. This leads to strip tip deformation, causing poor quality of the final product, which cannot stay fully plan. This work was developed around this problem, studying the best solution to develop a new tool able to avoid the lack of plate flatness after cut. A novel equipment was designed, able to be easily connected to the shearing machine, following the blade movement throughout cut operation. The system is fully-automated, being operated by a single cut instruction given by the machine operator. This system allows the manufacturing company to increase the added-value of each machine, offering advanced and desirable solutions to the customers, and contributing as well to the company business sustainability.68708

1. Introduction

Although being an old technology, blanking remains nowadays one of the most used cutting processes in metalworking industry  [1]. This technology was study many year ago but, recent developments brings new challenges such as adapting finite elements model to these technologies in order to predict new materials behaviour, explore the processes capacity having as focus to increase the production rate and implement new devices leading to a quality improvement regarding the new market requests and expectations. Accordingly, several studies have been carried out by different authors regarding, namely in  the field of the parameters improvement, with Breitling et al.  [2] exploring the competitiveness of the process and studying the blanking speed, concluding that blanking force drops with the increase of the blanking speed within the range of 1–4 m s−1, results whose were corroborated by Goijaerts et al.  [3] within the range of 0.01–1000 mm s−1. Further studies have been carried out by Neugebauer et al.  [4] and Subramonian et al.  [5] concluding that dynamic effect is higher when blanking speed increases, using a high speed mechanical press. Mackensen et al.  [6] studied the punch inclination angle, concluding that cutting forces are lower when punch inclination angle rises. However, higher punch inclination angles lead to blank curling. As referred by other authors  [7–9], a better geometrical accuracy of the blanked part can be achieved by an optimization of the punch shape

and die clearance. However, it remains clear that parameters such as tool wear state, clearance, tool radii and geometry, material geometry, sheet metal thickness, friction, relevant material properties regarding the cutting (ductility and hardness), sheet metal coating, lubrication use, stroke rate and blanking speed are the key-factors affecting the sheared edge aspect [10]. Thermal effects have been also intensively studied  in order  to correlate  the temperature  with the blanking  force

 [11–13] leading to realize that blanking forces fall when material temperature upsurges. These studies include pre-heating processes in order to lead the material temperature to perse levels and measure the needed blanking force to cut different materials. Many other studies have been carried out in the analytical and numerical methods field, trying to get reliable models helping researchers to predict blanking operations effect regarding different materials and cutting conditions whose are summarized in [10,14–16]. However, despite these strong efforts, the blanking cutting process still remains an attractive issue to investigate due to shear band formed narrowness and the lack of an appropriate fracture criterion.