Papers by Author: Francisco Javier Campa

Abstract: Ever increasingly, universities have to face the demands of their students regarding tools and methods to complete their education in preparation for the industrial environment. On the other hand, the university has to meet a Research and Development function oriented to the improvement of the competitiveness of that environment. These are two different functions that the university must unite to offer an optimum service. Hence, the university needs tools that can meet this dual function: teaching and researching. This paper proposes the concept of a “Glass Machine” as a dual purpose approach based on the adaptation of machine tools to satisfy that dual function. This concept has been applied to a machine tool by means of two machines: a turn-milling centre and a feed-drive test bench, which have been used for practices in the subjects of 4th and 5th year of Industrial Engineering, allowing at the same time the usual research activity of the High Performance Machining Team. In short, this work is about the optimization of the available resources of the university, thus satisfying the needs of the students and the industrial environment.

Abstract: A common problem in the aeronautical industry is the chatter vibration due to the lack of dynamic stiffness in the milling of thin walls and thin floors. The present work proposes a method for chatter avoidance in the milling of flexible thin floors with a bull nose end mill. It allows the calculation of the thickness previous to finish milling or the minimum dynamic stiffness that the floor must have to avoid the chatter vibration appearance. To obtain these values, the stability model algorithm has been inverted to estimate the thickness or the dynamic stiffness required in a floor to allow a stable milling. This methodology has been validated satisfactorily in several experimental tests.

Abstract: Chatter is the most classical problem in machining. It is prone to occur in low rigidity structures generating poor surface quality and harmful vibrations which could damage any part of the machine-tool system. In finishing operations, the effect of the tool nose radius should be taken into account in order to obtain safe and reliable cutting conditions. The present paper uses a simple SDOF model to study the stability during finishing operations.

Abstract: In this paper, a 3D dynamic model for the prediction of the stability lobes of high speed milling is presented, considering the combined flexibility of both tool and workpiece. The main aim is to avoid chatter vibrations on the finish milling of aeronautical parts, which include thin walls and thin floors. In this way the use of complex fixtures is eliminated. Hence, an accurate selection of both axial depth of cut and spindle speed can be accomplished. The model has been validated by means of a test device that simulates the behaviour of a thin floor.