A Survey on Cutting Parameter and Tool Path on Tool Deflection of Ti-6Al-4V Alloy in High-Speed Milling

Spherical inclined surfaces are sometimes experienced in the machining of segments in enterprises, for example, aircraft, aerospace, automotive, and accuracy apparatus assembling. Tool path, created by various cutting techniques, result in different cutting forces and deflection values that may prompt poor surface quality and dimensional deviation. In modern manufacturing producing, it is useful to make known their impacts on machinability. In this thesis, ideal cutting parameter values in ball end-milling processing of Ti-6Al-4V with three covered cutters has been investigated. The parameters thought about are cutting velocity, feed rate, cutting speed, and tool path style. The second point of the study is to decide the impacts of tool movement styles in ball end processing of inclined surfaces. Thus, the best parameter inside the chose cutting parameters and cutting styles for both inclined surfaces and distinctive coatings was venture over. As far as instrument coatings, the most quickly falling apart covering was TiC covering for cutting strengths in both inclined surfaces and for device deflection in spherical inclined surface. Moreover, the results showed that by measuring tool deflection different problems such as dimensional deviation could be controlled

Cutting Mechanics of the Gear Shaping Process

In the machining industry, there is a constant need to increase productivity while also maintaining dimensional tolerances and good surface quality. For many classical machining operations (e.g. milling, turning, and broaching), research has been established that is able to predict the part quality based on process parameters, workpiece material, and the machine’s dynamic characteristics. This allows process planners to design their programs virtually to maximize productivity while meeting the specified part quality. To accomplish this, it is necessary to predict the cutting forces during the machining operation. This can be done using analytical equations for a lot of operations; however, in more recent research for complicated processes (e.g. 5-axis milling, gear hobbing), this is done by calculating the cutter-workpiece engagement with geometric CAD modellers and calculating incremental cutting forces along the cutting edge. With knowledge of the cutting forces, static deflections and dynamic vibrations of the tool and workpiece can be calculated which is one of the most prominent contributors to dimensional part inaccuracies and poor surface quality in machining. The research presented in this thesis aims to achieve similar goals for the gear shaping process. Gear shaping is one of the most prominent methods of machining cylindrical gears. More specifically, it is the most prominent method for generating internal gears which are a major component in planetary gear boxes. The gear shaping process uses a modified external gear as a cutting tool which reciprocates up and down to cut the teeth in the workpiece. Simultaneously, the tool and workpiece are also rotating proportionally to their gear ratio which emulate the rolling of two gears. During the beginning of each gear shaping pass, the tool is radially fed into the workpiece until the desired depth of cut is reached. In this study, the three kinematic components (reciprocating feed, rotary feed, and radial feed) are mathematically modelled using analytical equations and experimentally verified using captured CNC signals from the controller of a Liebherr LSE500 gear shaping machine. To predict cutting forces in gear shaping, the cutter-workpiece engagement (CWE) is calculated at discrete time steps using a discrete solid modeller called ModuleWorks. From the CWE in dexel form, the two-dimensional chip geometry is reconstructed using Delaunay triangulation and alpha shape reconstruction which is then used to determine the undeformed chip area along the cutting edge. The cutting edge is discretized into nodes with varying cutting directions (tangential, feed, and radial), inclination angle, and rake angle. If engaged in cutting during a time step, each node contributes an incremental three dimensional force vector calculated with the oblique cutting force model. Using a 3-axis dynamometer, the cutting force prediction algorithm was experimentally verified on a variety of processes and gears which included an internal spur gear, external spur gear, and external helical gear. The simulated and measured force profiles correlate very closely (about 3-10% RMS error) with the most error occurring in the external helical gear case. These errors may be attributable due to rubbing of the tool which is evident through visible gouges on the finished workpiece, tool wear on the helical gear shaper, and different cutting speed than the process for which the cutting coefficients were calibrated. More experiments are needed to verify the sources of error in the helical gear case. To simulate elastic tool deflection in gear shaping, the tool’s static stiffness is estimated from impact hammer testing. Then, based on the predicted cutting force, the elastic deflection of the tool is calculated at each time step. To examine the affect of tool deflection on the final quality of the gear, a virtual gear measurement module is developed and used to predict the involute profile deviations in the virtually machined part. Simulated and measured profile deviations were compared for a one-pass external spur gear process and a two-pass external spur gear process. The simulated profile errors correlate very well with the measured profiles on the left flank of the workpiece, however additional research is needed to improve the accuracy of the model on the right flank. Furthermore, the model also serves as a basis for future research in dyamic vibrations in gear shaping. The above-mentioned algorithms have been implemented into a tool called ShapePRO (developed in C++). The software is meant for process planners to be able to simulate the gear shaping operation virtually and inspect the resulting quality of the gear. Accordingly, the user may iterate the process parameters to maximize productivity while meeting the customer’s desired gear quality

Process Comprehension for Interoperable CNC Manufacturing

Over the last 40 years manufacturing industry has enjoyed a rapid growth with the support of various computer-aided systems (CAD, CAPP, CAM etc.) known as CAx. Since the first Numerically Controlled (NC) machine appeared in 1952, there have been many advances in CAx resource capabilities. The information integration and interoperability between different manufacturing resources has become an important and popular research area over the last decade. Computer Numerically Controlled (CNC) machines are an important link in the manufacturing chain and the major contributor to the production capacity of manufacturing industry today. However, most of the research has focused on the information integration of upper systems in the CAD/CAPP /CAM/CNC manufacturing chain, leaving the shop floor as an isolated information island. In particular, there is limited opportunity to capture and feed shopfloor knowledge back to the upper systems. Furthermore, the part programs for the machines are not exchangeable due to the. machine specific postprocessors. Thus there is a further need to consider information interoperability between different CNC machine and other systems. This research investigates the reverse transformation of the CNC part programmes into higher level of process information, entitled process comprehension, to enable the shopfloor interoperability. A novel framework of universal process comprehension is specified and designed. The framework provides a reverse direction of information flow from the CNC machine to upper CAx systems, enabling the interoperability and recycling of the shopfloor knowledge. A prototype implementation of the framework is realised and utilised to demonstrate the functionalities through three industrially inspired test components. The major contribution of this research to knowledge is the new vision of the shopfloor interoperability associated with process knowledge capture and reuse. The research shows that process comprehension of part programmes can provide an effective solution to the issues of the shopfloor interoperability and knowledge reuse in manufacturing industries.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Predicción de fuerzas de corte y topografía superficial para la mejora de fresado de rotores de álabes integrados.

179 p.Los rotores de álabes integrados consisten en discos rotativos con álabes fabricados en una sola pieza, los cuales están siendo cada vez más utilizados en los motores aeronáuticos debido a sus ventajas en cuanto a fiabilidad, reducción del peso, eficiencia y reducción de ruido. Estos componentes plantean uno de los problemas más difíciles desde el punto de vista del mecanizador, ya que se combinan tres factores críticos: 1) el fresado de superficies complejas en 5 ejes continuos, 2) materiales de baja maquinabilidad que generan grandes fuerzas de corte y altas temperaturas durante el mecanizado y, por último, 3) presencia de paredes delgadas y estructuras poco rígidas que son propensas a deformarse o vibrar durante el mecanizado.En este trabajo se define una metodología fiable de diseño y verificación de operaciones de fresado en cinco ejes de IBR-s. En una primera fase experimental de fabricación de geometrías de impeller y blisk, se han estudiado y analizado los diferentes tipos de operaciones de desbaste y acabado, así como lasherramientas de geometría tradicional y las de nuevo diseño. En concreto, existe gran interés enintroducir las nuevas geometrías de fresa de barril en el sector aeronáutico en operaciones desemiacabado y acabado de álabes. El elevado radio de curvatura del contorno permite reducir el númerode pasadas, y por lo tanto el tiempo de mecanizado, sin aumentar el tamaño de la herramienta.Para completar la metodología propuesta se han desarrollado herramientas predictivas de la topografía yrugosidad superficial de la pieza, y de las fuerzas de corte del proceso. Por un lado, se ha validado unmodelo de predicción basado en la substracción de sólidos, para operaciones de fresado periférico confresa cilíndrica considerando la flexión estática de la pared. Por otro lado, se han desarrollado dosmodelos enfocados a las operaciones de cinco ejes con fresas de barril. El primero de ellos permite simular la topografía y rugosidad teniendo en cuenta el runout de la herramienta y la orientación de la fresa. El segundo modelo propuesto predice las fuerzas de corte en mecanizados utilizando fresas de barril, para condiciones de corte estacionarias y en las que no se producen de flexión de pieza o herramienta