Spiral Bevel Gears Face Roughness Prediction Produced by CNC End Milling Centers

The emergence of multitasking machines in the machine tool sector presents new opportunities for the machining of large size gears and short production series in these machines. However, the possibility of using standard tools in conventional machines for gears machining represents a technological challenge from the point of view of workpiece quality. Machining conditions in order to achieve both dimensional and surface quality requirements need to be determined. With these considerations in mind, computer numerical control (CNC) methods to provide useful tools for gear processing are studied. Thus, a model for the prediction of surface roughness obtained on the teeth surface of a machined spiral bevel gear in a multiprocess machine is presented. Machining strategies and optimal machining parameters were studied, and the roughness model is validated for 3 + 2 axes and 5 continuous axes machining strategies. Palabras claveThank you to the Department of Education, and to the Universities and Research program of the Basque Government for their financial support, by means of the ZABALDUZ program. We also thank the UFI in Mechanical Engineering department of the UPV/EHU for its support of this project

Tool Wear Improvement and Machining Parameter Optimization in Non-generated Face-hobbing of Bevel Gears

Face-hobbing is the dominant and the most productive machining process for manufacturing bevel and hypoid gears. Bevel gears are one of the most important power transmission components, in automobile to aerospace industries, where the power is transmitted between two non-parallel axes. In current industries, the face-hobbing process confronts two major challenges, the tool wear and trial and error experiments to select machining parameters. In the present work, these two problems are targeted. The tool wear in face-hobbing happens at the tool corners of the cutting blades due to the multi-flank chip formation and large gradient of working rake and relief angles along the cutting edge at the corners. In addition, the cutting fluid absence contributes in the tool wear phenomena. In the present work, a cutting tool design method is proposed in order to improve the tool wear characteristics especially at the tool corners. The rake and relief surfaces of the conventional cutting blades are re-designed in such a way that normal rake and relief angles during the face-hobbing process are kept constant and consequently the gradients of these two angles are minimized, theoretically to zero. Using mathematical tool wear characterization relationship and also FEM simulation, the improvements in tool wear are approved. In addition, in the present thesis, semi-analytical methods are proposed to optimize the face-hobbing process in order to select appropriate machining settings. The optimization problem is constructed in such a way that the machining time is minimized subject to the tool rake wear or cutting force related constraints. In order to predict the tool rake wear (crater wear depth), methods are proposed to calculate un-deformed chip geometry, cutting forces, normal stresses, interface cutting temperature and chip sliding velocity. The un-deformed chip geometry is obtained using two proposed methods numerically and semi-analytically. In the numerical method, the workpiece in-process model is obtained and then the un-deformed chip geometry is approximated using the in-process model. In the semi-analytical method, an un-deformed chip boundary theory is constructed in such a way that the boundary curves of the un-deformed chip are formulated by closed form equations. The obtained un-deformed chip geometry is discretized along the cutting edge of the blades. Each infinitesimal element is considered as a small oblique cut. The differential cutting forces are predicted for each individual element using oblique cutting transformation theory. The total cutting forces are derived by integrating the differential cutting forces along the cutting edge. The proposed methods are applied on case studies of non-generated face-hobbing of gears to show the capability of the methods to find the un-deformed chip geometry, predict cutting forces and finally find the optimum machining parameters in non-generated face-hobbing

Special Issue of the Manufacturing Engineering Society (MES)

This book derives from the Special Issue of the Manufacturing Engineering Society (MES) that was launched as a Special Issue of the journal Materials. The 48 contributions, published in this book, explore the evolution of traditional manufacturing models toward the new requirements of the Manufacturing Industry 4.0 and present cutting-edge advances in the field of Manufacturing Engineering focusing on additive manufacturing and 3D printing, advances and innovations in manufacturing processes, sustainable and green manufacturing, manufacturing systems (machines, equipment and tooling), metrology and quality in manufacturing, Industry 4.0, product lifecycle management (PLM) technologies, and production planning and risks

Metodología para obtención de parámetros de corte en alesadora horizontal CNC considerando aspectos de máquina herramienta y su aplicación en el montaje experimental

Los engranajes son elementos de transmisión de potencia usados en la mayoría de las máquinas. Debido a sus características frente a otros sistemas de transmisión de potencia, anualmente se producen billones de engranajes, aunque su fabricación sea costosa y compleja. Este trabajo presenta las calidades geométricas, dimensionales y de rugosidad obtenidas tras implementar una metodología de obtención parámetros de corte. El piñón y la rueda fueron fabricados en máquinas CNC de propósito general, el piñón de acero en centro de mecanizado y la rueda de fundición nodular en alesadora horizontal. Los parámetros de corte para la fresa escariadora punta esférica diámetro 6 mm se utilizaron: avance por diente 0,02mm, velocidad de corte 110m/min, profundidad de corte 0,8mm y avance radial: 0,12mm. La orientación de la herramienta se definió con 6,5° y 46,5° según la dirección de avance de la herramienta. Dos simulaciones y verificaciones integradas se ejecutaron para validar trayectorias de la herramienta y generar códigos de control numérico. La metrología dimensional se realizó por métodos de escaneo por palpado y óptico. La rugosidad Ra mínima obtenida tras aplicar el método de superficie de respuesta fue de 2,080 µm y las desviaciones geométricas y dimensionales máximas fueron del orden de 0,5mm. La metodología implementada permitió obtener un engranaje calidad ISO17485 entre 7 y 10. Fue posible fabricar engranajes con máquinas de propósito general y se propuso modelo experimental para predicción de rugosidad con coeficiente de determinación del 80%.Gears are power transmission elements used in most machines. Due to its characteristics compared to other power transmission systems, billions of gears are produced annually, although their manufacture is expensive and complex. This work presents the geometric, dimensional and roughness qualities obtained after implementing a methodology for obtaining cutting parameters. The pinion and wheel were made on general purpose CNC machines, the steel pinion on machining center and the nodular cast iron wheel on horizontal milling machine. Cutting parameters for 6 mm diameter ball end mill were used: feed per tooth 0,02mm, cutting speed 110m / min, depth of cut 0,8mm and radial depth of cut: 0,12mm. Tool orientation was defined in 6,5° and 46,5° according to feed direction. Two simulations and integrated verifications were run to validate toolpaths and generate numerical control codes. Dimensional metrology was performed by scanning and optical scanning methods. The minimum Ra roughness obtained after applying the response surface method was 2,080 µm and the maximum geometric and dimensional deviations were by 0,5mm. The implemented methodology allowed obtaining a quality ISO17485 gear between 7 and 10. It was possible to manufacture gears with general-purpose machines and an experimental model for roughness prediction with a coefficient of determination of 80% was proposed.Línea de Investigación: Procesos de Manufactura y MetalurgiaMaestrí

Bibliography of Lewis Research Center technical publications announced in 1985

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1985. All the publications were announced in the 1985 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses