L. Sevilla

Modular Procedure to Improve the Application of the Upper-Bound Theorem in Forging

The application of the Upper Bound Theorem (UBT) to plane strain forging processes using Triangular Rigid Blocks (TRB) is not a simple task when trying to adapt the blocks to different workpiece geometries. In this article, a modular procedure is proposed to obtain the best configuration of modules that determines the minimum value of required force to reach the desired state of deformation. This particular approach is called “modular” and the number of modules is modified when forming the workpiece by changing the so called “shape factor,” that is the ratio of the width and the height of the workpiece section to be analyzed. The methodology to follow is carefully explained and minimum curves are determined for different geometrical cases and friction conditions, being the results validated by means of FE analysis.

Implementation of Technological and Geometrical Parameters in Forging Processes by Means of the Upper Bound Element Technique

Present work is applied to the upper bound elemental technique (UBET) with the triangular rigid zones model in forging processes. This application allows incorporating different technological and geometrical parameters, not usually used at this analytic method. The strain hardening and the influence of the temperature are someone of these parameters considered. In the other side, friction with shear factor and sliding (Coulomb) factor are estimated, even simultaneously. A fundamental advantage in the application of the proposed method is its adaptation on a free die‐block profile not limited to parallel and plane surfaces, by means of combined profiles with different inclinations.

Analytical Approach to the Indentation Process. Application of the Upper Bound Element Technique

Present work poses, from the methodological point of view, an approach to a case offorging by indentation by means of the application of the Upper Bound Element Technique(UBET), in his development of triangular rigid blocks (TRB). With two approaches of differentnature (Modulate and not Modulate), it tackles the study of the evolution of the necessary minimumenergy to attain the required deformation. The UBET allows a suitable implementation of theboundary conditions of the process, as well as the characteristic of the same, such as the kind offriction or the geometrical considerations, without limit on the flow of material in contrary directionto the applied load by the tool.

Experimental Validation of the New Modular Application of the Upper Bound Theorem in Indentation

Nowadays, thanks to the new manufacturing processes, indentation is becoming an essential part of the new arising processes such as the Incremental Forming Processes. This work presents the experimental validation of the analytical model developed for an indentation-based process. The analytical model is originated from the Upper Bound Theorem application by means of its new modular distribution. The modules considered are composed of two Triangular Rigid Zones each. The experimental validation is performed through a series of indentation tests with work-pieces of annealed aluminium EN AW-2030 and punches of steel AISI 304, under plane strain conditions. The results are compared with the ones obtained from the application of this new modular distribution of the Upper Bound Theorem, showing a good approximation and suitability of the model developed for an indentation-based process.

Cutting Speed-Feed Coupled Experimental Model for Geometric Deviations in the Dry Turning of UNS A97075 Al-Zn Alloys:

In this work a study of the influence of cutting speed and feed on different geometric deviations (straightness, parallelism, roundness, and circular run-out) of dry turned UNS A97075 (Al-Zn) cylindrical bars has been carried out. The experimental data have revealed a low sensitivity to change of these deviations with cutting speed and feed, within the range of cutting parameters evaluated. In addition, several parametric models have been developed from the experimental results. These models allow predicting the behavior of these deviations as a function of cutting parameters applied. In order to do this, different parametric models (potential, exponential, and polynomial) have been tested. For all analyzed geometric deviations, the exponential model has shown the best fit to the experimental data.

A proposal of cost-tolerance models directly collected from the manufacturing process

In this paper, the concept of cost-tolerance functions based on data directly obtained from the manufacturing process is proposed. Traditional models used in manufacturing field define cost-tolerance relationships from mathematical functions whose relationship with the process is not usually set in a clear way. In this work, proposed models allow to obtain cost-tolerance functions directly from parameters measured on manufacturing process. The paper defines some of these functions using statistical distributions derived from the population of manufactured parts. A general methodology to reach a cost-tolerance function from any distribution of the manufactured parts is proposed. Once functions are defined, an application example is presented. Finally, the main criteria for suitable appropriateness use of models are established.

Selection of the Optimal Distribution for the Upper Bound Theorem in Indentation Processes

It has been established, in previous studies, the best adaptation and solution for the implementation of the modular model, being the current choice based on the minimization of the p/2k dimensionless relation obtained for each one of the model, analyzed under the same boundary conditions and efforts. Among the different cases covered, this paper shows the study for the optimal choice of the geometric distribution of zones. The Upper Bound Theorem (UBT) by its Triangular Rigid Zones (TRZ) consideration, under modular distribution, is applied to indentation processes. To extend the application of the model, cases of different thicknesses are considered

Experimental Parametric Model for Indirect Adhesion Wear Measurement in the Dry Turning of UNS A97075 (Al-Zn) Alloy

In this work, the study of the influence of cutting parameters (cutting speed, feed, and depth of cut) on the tool wear used in in the dry turning of cylindrical bars of the UNS A97075 (Al-Zn) alloy, has been analyzed. In addition, a study of the physicochemical mechanisms of the secondary adhesion wear has been carried out. The behavior of this alloy, from the point of view of tool wear, has been compared to similar aeronautical aluminum alloys, such as the UNS A92024 (Al-Cu) alloy and UNS A97050 (Al-Zn) alloy. Furthermore, a first approach to the measurement of the 2D surface of the adhered material on the rake face of the tool has been conducted. Finally, a parametric model has been developed from the experimental results. This model allows predicting the intensity of the secondary adhesion wear as a function of the cutting parameters applied.

Analysis of the Integrated Implementation of the Manufacturing Engineering Subject in Engineering Degrees at the Malaga University

In this paper the integrated implementation of the Manufacturing Engineering subject in all new engineering degrees at the University of Malaga is analyzed, within the European Higher Education Area (EHEA) framework. After identifying the methodology used by Department of Engineering Manufacturing Process and the problems generated in its development, the robustness of the designed organization system is justified. This methodology has successfully overcome the negative effects of multiple changes made to the delivery of the first edition of this subject. Additionally, the methodology developed has generating a significant level of student satisfaction by comparison with near departments and overall university.

Adaptive model to apply the Upper-Bound Theorem in plain strain forging

Present work applies the Upper-Bound Theorem (UBT) with Triangular Rigid Blocks (TRB) to metal forming compression processes like plane strain forge, offering an upper limit to required deformation energy. This analytical method, usually used by means of simplified models, is developed here incorporating different effects that impact in evolution of deformation process like shape factor and friction. By means of a new adaptive model, the shape and size of the rigid zones used for the UBT application are optimized according to the ratio of the width and the height of workpiece.