Punching with a slant angle - cutting surface quality

For economic or process-related reasons, punching of structural sheet metal components often has to be used for car bodies. The difference in angle of attack between punch and sheet metal component is referred to as “slant angle”. However, at the current state of the art, no precise information is available on the characteristics of cutting surfaces in relation to the slant angles. For this reason, cost-intensive slider units are used for comparatively small slant angles of around 10° in order to ensure series suitability of corresponding punching processes. In this respect, recent studies performed by the authors have shown that good cutting surface qualities can also be achieved for slant angles distinctly beyond 10°. This contribution presents an empirical test series for the characterization of cutting surface parameters when punching with a slant angle. Here, the experimental cutting surface analysis showed an asymmetric characteristic of the cutting surface along the hole circumference. Furthermore, the investigated sheet metal materials HC340LA, DP600 and DP800 revealed recurring tendencies regarding the parameters “edge draw-in”, “clean cut”, “fracture surface” and “burr height”, which had been combined to corresponding three-dimensional regression models. With these regression models, cutting simulations could be calibrated, allowing a quality prognosis of cutting surfaces achievable when punching at specific slant angles.

Uniformity, Periodicity and Symmetry Characteristics of Forces Fluctuation in Helical-Edge Milling Cutter

Under most processing conditions, the milling force is expected to be stable and not to fluctuate, in order to improve the processing quality. This study focuses on analyzing the force fluctuation characteristics under conditions of different processing and cutter parameters. An original model is proposed to predict the force fluctuation during the milling process of a helical-edge cutter. At the same time, three force fluctuation characteristics related to the axial cutting depth and cutter parameters are determined: uniformity, periodicity and symmetry. The corresponding mathematical derivation and proof method are given for the first time through a force transformation of projecting the superposition chip thickness on a virtual cutting edge. On this basis, a fast estimation method and an accurate simulation method for force fluctuation prediction are established to quantify the intensity of force fluctuations under different parameters. Both two prediction methods and the experimental cutting tests validate the proposed theory effectively. The result shows a high potential of the proposed theory for studying the force behavior under different milling parameters or cutter parameters and at least 75% of the test workload can be reduced.

JOHNSON–COOK MODEL COMBINED WITH COWPER–SYMONDS MODEL FOR BONE CUTTING SIMULATION WITH EXPERIMENTAL VALIDATION

Constitutive models are widely used to predict the mechanical behavior of different kinds of materials. Although the Johnson–Cook model for bovine bone and Cowper–Symonds model for human thoracic rib and tibia was developed, the predictability of these models was found good only at particular strain rates. This study addresses this lack of information by investigating the Cowper–Symonds model, Johnson–Cook model, and Johnson–Cook model combined with Cowper–Symonds model at different strain rates to utilize in the bone cutting simulation. Specimens prepared using two rear femurs harvested from a 3.50-year-old bovine were investigated at different strain rates (0.00001–1/s). A comparative study made among the stresses predicted from these models showed 29.41%, 10.91%, and 11.11% mean absolute percentage errors using Cowper–Symonds model, and 2.03%, 7.19%, and 3.62% mean absolute percentage errors using Johnson–Cook model, respectively, at 0.0001, 0.001 and 1/s strain rates. However, the Johnson–Cook model combined with the Cowper–Symonds model predicted the stress with a maximum of only 2.03% mean absolute percentage error. The potential of each model to utilize in the orthogonal bone cutting was also evaluated using Ansys® and found that the combined model predicted the cutting force close to experimental cutting force with minimal error (5.20%). The outcomes of this study can be used in the surgical practice and osteotomy procedure before commencing actual surgery.

Study and Development of a Multilayered Coating to Improve Hard Metal Cutting Tools Performances

The use of coated hard metal is spread in all fields of mechanical working, both forming and machining. Different hard metals are used based on their mechanical characteristic that strongly depends on composition and grain size. Substrates such as HSS and WC – Co are typically coated with PVD thin layers in applications such as metalworking and cutting; thus lot of efforts are put in researching this specific field. Coating composition, and coating architecture are paramount topics in the subsject of surface anti – wear thin films. The focus of this study is to analyze the difference between two AlTiN coatings, a monolayer and a multilayer with gradient composition, from the point of view of microstructure and adhesion. Experimental cutting tests were done to characterize the behavior of the coating in face milling of AISI 660 heat resistant alloy: varying cutting speeds from 15 to 40 m/min it was finally assessed that a multilayer coating can give higher tool life with respect to a monolayer coating of the same composition.

Experiments of Drilling Titanium Alloy with Varying Operation Parameters

Drilling experiments of titanium alloy Ti6Al4V were conducted. Taking the speed and feed as the process variables, a set of experimental cutting forces are obtained and compared. From the experimental results it is concluded that within the experimental extent the thrust force and torque of drilling process rises with the feed rate. The lower spindle speed resulted in the greater amount of thrust. Feed rates have greater influence on the thrust force than the spindle speed. The combination of greater feed rate and lower spindle speed results in the maximum amount of thrust. However, combination of greater feed rate and spindle speed resulted in maximum amount of torque.

La mejora en la adquisición de conocimientos ante una renovación metodológica de aprendizaje / The Improvement in the Acquisition of Knowledge to a Methodological Renewal of Learning

ABSTRACTThis study aims to test the effectiveness of learning through a methodology with ICT over the traditional method. The methodology used in the research is characterized as a prospective study (planned); Experimental cutting with pretest and posttest; and using different techniques and tools for collecting information. This study was conducted through a questionnaire to 77 students Grade of "Early Childhood Education" and "Primary Education" of the University CEU Cardenal Herrera, Castellon. Initially the students completed a questionnaire (pretest) and then they were divided into two groups; in one group was imparted a traditional session and in the other group a session with ICT tools, on a new unknown content in both groups. After analyzing the results it can be concluded that students acquire better knowledge of traditional form. This may be because almost all students have received teaching (pre-university) by the traditional method, which may influence their styles learning. There is also a gender difference, as there is a variation of this variable for the ICT method and the traditional method.RESUMENEl presente estudio pretende comprobar la eficacia del aprendizaje mediante una metodología en la que se utilizan las tecnologías frente al método tradicional. La metodología empleada en la investigación se caracteriza por ser un estudio prospectivo (planeado); de corte experimental con pretest y postest; y que utiliza diferentes técnicas y herramientas para la recogida de información. El estudio se llevó a cabo mediante un cuestionario a 77 alumnos de Grado de Educación Infantil y Primaria de la Universidad Cardenal Herrera CEU de Castellón. Inicialmente los alumnos cumplimentaron un cuestionario (Pretest) y posteriormente se dividieron en dos grupos impartiéndose a un grupo una sesión tradicional y al otro una sesión con herramientas TIC sobre un nuevo contenido desconocido en ambos grupos. Tras el análisis de los resultados se puede concluir que los alumnos adquieren mejor los conocimientos de forma tradicional. Esto puede deberse a que prácticamente la totalidad de los alumnos han recibido la docencia (preuniversitaria) mediante el método tradicional, lo cual puede influir en sus estilos cognitivos de aprendizaje. Cabe destacar la gran diferencia existente entre la adquisición de conocimientos en función del género que se da mediante la herramienta TIC y que no existe mediante el método tradicional. Contacto principal: [email protected]

Application of Taguchi Method Machining to CuA1

This paper is to study the application of Taguchi Method when experimental cutting on Copper (CuA1) generated by a milling machine. The respone of this study is surface roughness while machining with varying machining parameters such as cutting speed, feed rate and depth of cut. This experiment is using end mill HSS Ø16mm with uncoated and 2 flute with sequences of experiment base on the Taguchi Orthogonal array L934which carry out with 9 of experiments. The signal-to-noise (S/N) ratio, the analysis of variance (ANOVA) and confirmation tests with the optimal levels of machining parameters are carried out in order to illustrate the effectiveness of the Taguchi optimization method.