Five-axis Flank Milling and Modeling the Spiral Bevel Gear with a Ruled Tooth Surface Design

Spiral bevel gears usually are cut by the machine tools which are specifically made for manufacturing spiral bevel gear. For some practical applications, such as repair, prototype, and small batch, there are only several spiral bevel gears need to be machined. It seems not wise to buy a gear manufacturing machine tool for cutting those several gears. Consequently, some other manufacturing methods are introduced to cope with this situation. Recent advances in computer numerical control (CNC) milling machine tools make it possible to manufacture good quality spiral bevel gears. Moreover, CNC milling machine tools are usually cheaper than the specific gear manufacturing machine tools. Even more, they are not only cut gears but also other parts. Therefore, computer numerical control (CNC) milling is introduced in industry to cut spiral bevel gears. End milling and flank milling are two modes of CNC milling. Compared to end milling, flank milling has been highlighted in quality enhancement, manufacturing time and cost reduction. Theoretically, the result of flank milling a developable ruled surface does not contain geometric deviations. Hence, flank milling has been widely used to machine the parts with ruled surface or the surface close to ruled surface, such as turbines and blades. Due to the fact that the tooth surfaces of spiral bevel gears are close to ruled surface (the tooth surface of Format-cut spiral bevel is part of a cone), flank milling can also be used to cut spiral bevel gears. However, there is no literature about flank milling spiral bevel gears. Moreover, the current existing tooth surface models (except the tooth surface of Format-cut spiral bevel gear) are implicit, which makes further calculation inefficient and difficult. To address these two problems, a new ruled tooth surface design is proposed to spiral bevel gears design. Subsequently, the design model is used to be machined with five-axis flank milling by introducing a new tool path planning approach. To obtain the simulate machined tooth surface, a new geometric envelope approach is proposed to calculate the cutter envelope surface as a closed-form representation. Then the result of geometric deviations, which are obtained by comparing the design tooth surface and the simulate machined tooth surface, shows the flank milling is appropriate to cut spiral bevel gears. Furthermore, the conventional face-milled model is also used as the design model for flank milling, and another result of geometric deviations is obtained. Subsequently, both results are compared, and the comparison shows that the proposed design reduces the geometric deviations effectively. Moreover, the closed-form simulate machined tooth surface can only be obtained by using the proposed design

Characterizing envelopes of moving rotational cones and applications in CNC machining

Motivated by applications in CNC machining, we provide a characterization of surfaces which are enveloped by a one-parametric family of congruent rotational cones. As limit cases, we also address ruled surfaces and their offsets. The characterizations are higher order nonlinear PDEs generalizing the ones by Gauss and Monge for developable surfaces and ruled surfaces, respectively. The derivation includes results on local approximations of a surface by cones of revolution, which are expressed by contact order in the space of planes. To this purpose, the isotropic model of Laguerre geometry is used as there rotational cones correspond to curves (isotropic circles) and higher order contact is computed with respect to the image of the input surface in the isotropic model. Therefore, one studies curve-surface contact that is conceptually simpler than the surface-surface case. We show that, in a generic case, there exist at most six positions of a fixed rotational cone that have third order contact with the input surface. These results are themselves of interest in geometric computing, for example in cutter selection and positioning for flank CNC machining.RYC-2017-2264

A Practical and Optimal Approach to CNC Programming for Five-Axis Grinding of the End-Mill Flutes

For a solid carbide tapered end-mill, every flute includes a flute surface and a rake face along a helical side cutting edge, and the end-mill core is at the center and is tangent to all the flutes. The flutes significantly affect the tools cutting performance and life, and the core radius mainly affects the tools rigidity. Mainly, two methods are adopted in industry to grind the flutes; these are: the direct method and the inverse method. In the direct method, a flute is ground using a standard grinding-wheel moving in multi-axis machining to generate the rake face and the flute surface. However, the flute is the natural outcome of the grinding process without any control. On the other side, the inverse method employs the concept of inverse engineering to build a grinding-wheel that accurately grinds the end-mill flutes. This yields a free-form grinding-wheel profile that is used on a 2-axis grinding machine; however, the flute shapes are only exact on one section of the end-mill; when the grinding-wheel moves along the side cutting edge to smaller sections; the deviation of the generated flute from the designed one will be increased. Thus, neither can this method grind the rake face with the prescribed normal rake angle, nor generate the side cutting edge in good agreement with its design. Moreover, the grinding-wheel profile is very difficult and expensive to make. To address these problems, a practical and optimal approach for five-axis grinding of prescribed end-mill flutes is proposed by; first, establishing a 5-axis flute grinding theory describing the wheels locations and orientations during grinding the rake faces with constant normal rake angles; Second, introducing a simple grinding-wheel consisting of lines and circular arcs; and finally, applying an optimization algorithm to optimize the grinding-wheel shape and path. Overall, this approach significantly advances the CNC programming technique for the 5-axis flute grinding, and can substantially increase the quality of the solid carbide end-mills and lays a good foundation for the CAD/CAE/CAM of end-mills. The advantages of this approach over the other approaches are verified using computer simulation

Swept volume evaluation using the BSP-dexel representation for the 5-axis CNC machining simulation

A new approach to the construction of a volume swept by the cutting tool is proposed for modeling 5-axis computer numerical control milling. A tool is considered to take the form of an arbitrary body of revolution. The main difference of the proposed approach is to provide the possibility of direct construction of the bulk synchronous parallel-dexel model, which, in turn, provides an effective modeling of the cutting process. Thus, it was possible to expand the scope of the given model by including the possibility to simulate arbitrary 5-axis computer numerical control programs. To confirm the correctness of the proposed approach, a program implementation of the corresponding algorithms has been performed. Examples of modeling of 5-axis milling processing of real parts and data on time costs for the suggested modeling are given. The high efficiency of the proposed approach is proven by the results of the experiments

Learning from experience in the engineering of non-orthogonal architectural surfaces: A computational design system

This research paints a comprehensive picture of the current state of the conception and engineering of non-orthogonal architectural surfaces. The present paradigm in the design and engineering of these elaborate building structures is such that the overall form is decided first and it is then broken down into building components (façade cladding, or structural or shell elements) retrospectively. Subsequently, there is a division between the creation of the design and then the reverse engineering of it. In most of these projects, the discretisation of elaborate architectural surfaces into building components has little to do with how the form has been created, and the logic of the global form and its local subdivision are not of the same order. Experience gained through project work in the sponsoring company Buro Happold has been harnessed to inform the implementation of a design tool prototype. It is an open, extendable system. The development of the tool aims at stepping outside the current paradigm in practice; provides an integrated process of bottom-up generation of form and top-down search and optimisation, using an evolutionary method. The assertion of this thesis is that non-orthogonal design, which mimics a natural form in appearance, can be derived using mechanisms found in nature. These mechanisms, e.g. growth and evolution, can be transferred in such a way that they integrate aspects of the aesthetic, manufacturing, construction or performance. Designs are then created with an inherent logic. Growing form by adding discrete local geometries to produce larger componential surfaces ensures that the local parts and the global geometry are coherent and of the same kind. The aspiration is to make use of computational methods to contribute to the design and buildability of non-orthogonal architectural surfaces, and to further the discussion, development and application of digital design tools in practice

Европейский и национальный контексты в научных исследованиях - 2021 : Технология

В настоящем электронном сборнике «Европейский и национальный контексты в научных исследованиях. Технология» представлены работы молодых ученых по геодезии и картографии, химической технологии и машиностроению, информационным технологиям, строительству и радиотехнике. Предназначены для работников образования, науки и производства. Будут полезны студентам, магистрантам и аспирантам университетов.=In this Electronic collected materials “European and national dimension in research. Technology” works in the fields of geodesy, chemical technology, mechanical engineering, information technology, civil engineering, and radio-engineering are presented. It is intended for trainers, researchers and professionals. It can be useful for university graduate and post-graduate students

Aeronautical engineering: A continuing bibliography with indexes

This bibliography lists 425 reports, articles and other documents introduced into the NASA scientific and technical information system in January 1985

CAD-Methodik zur Produktivitätssteigerung in der Prozesskette Konstruktion-Fertigung

Danksagung Für die wissenschaftliche und methodische Unterstützung während meiner gesamten Zeit als wissenschaftliche Mitarbeiter und Doktorand am Lehrstuhl für Rechnereinsatz in der Konstruktion gilt mein Dank meinem Doktorvater Prof. Dr.-Ing. Dipl.-Math. Peter Köhler sowie allen Lehrstuhlkollegen, vor allem jedoch Dr.‐Ing. Alexander Martha, Thivakar Manoharan M. Sc., Phil Hungenberg M. Sc. und René Andrae M. Sc. Unstrittig ist, dass der Konstrukteur für die anforderungsgerechte Produktauslegung und Produkt-gestaltung verantwortlich ist und damit maßgeblich die Qualität und die Herstellkosten beeinflusst. Die Kompliziertheit und Komplexität der Konstruktionslösungen verhindert häufig eine angemessene Sichtweise auf die Herstellkosten bzw. auf Alternativen zur Herstellung eines Produktes. Die Kosten entstehen zumeist erst, wenn das Produkt durch die Fertigungsabteilung realisiert wird. Um dieser großen Kostenverantwortung der Konstruktion besser gerecht werden zu können, wird im Rahmen der Dissertation die technische Produktivität in der Prozesskette Konstruktion-Fertigung, welche sich über die Begriffe Effektivität und Effizienz ausdrücken lässt, betrachtet. Es werden Antworten auf die Fragen formuliert: Was kann getan werden, um die Produktivitätssteigerung in der heutigen Prozesskette Konstruktion-Fertigung zu erreichen? Bei der Beantwortung dieser Frage werden CAD-Methoden vorgestellt, welche die Einbeziehung des Fertigungswissens in ein möglichst frühes Stadium des Entwicklungs- und Konstruktionsprozesses ermöglichen. Anhand von ausgewählten Problemfeldern für Bohr-, Dreh- und Fräsprozesse werden Lösungen zum zerspanungsorientierten Geometrieaufbau und der Fertigbarkeitsanalyse der 3D-CAD-Modelle aufgezeigt. Durch die Implementierung der Methoden und die Entwicklung einer spe-ziellen, zerspanungsorientierten Umgebung im 3D-CAD-System wird dem Konstrukteur die Möglichkeit gegeben, den Produktmodellierungsprozess an Konstruktionsrichtlinien und projektspezifischen fertigungstechnischen und wirtschaftlichen Randbedingungen zu orientieren. Durch den Einsatz spezieller Methoden der wissensbasierten Konstruktion (KBE) und angepasster Web-Techniken (Webservice) werden die in einem fertigungsorientierten Form-Feature gebündelten, geometrischen Informationen um weitere technologische Parameter, wie Werkzeuge, Werkzeugparameter, Verfahrwege und notwendige Fertigungsvorgänge (wie z. B. Schruppen und Schlichten) ergänzt. Für komplexere Geometrieausprägungen werden flächenbasierte Modellierungsmethoden zur Gestaltung räumlicher und fertigungskonformer Werkzeugbewegungshüllen bereitgestellt. Diese insgesamt höherwertigen, fertigungsorientierten Features stellen die Basis für die konstruktionsbegleitende Kostenabschätzung und die CAD-CAM-Kopplung dar. Dabei werden die fertigungsrelevanten Daten und Informationen in der CAM-Umgebung extrahiert, sodass für jeden Fertigungsschritt die dafür benötigten Fertigungsoperationen auf einfache Weise abgeleitet werden können. Somit ergibt sich letztlich eine durchgängige Prozesskette zwischen der Konstruktion und Fertigung, welche auch die Qualität von CAD-CAM-Kopplungen erhöhen kann.It is indisputable that a design engineer is responsible for the requirement-driven functional and geometrical design of new products and that through this responsibility, has a significant impact on the associated quality and manufacturing costs. The complexity of the design solutions often prohibits an adequate assessment of the production costs and can make it difficult to consider alternative manufacturing methods. The manufacturing costs normally emerge only once the product is phased into production. In order to allow the design engineer to better fulfill this responsibility for product costs, this dissertation considers the technical productivity (expressed with the terms effectivity and efficiency) of the process chain between the design engineering and production departments. There are answers to the questions formulated: What can be done to achieve an improvement in the current process-chain between the design engineering and production departments? In answering this question, CAD methods will be introduced which allow the inclusion of production knowledge into the earliest possible stages of the design and development process. Considering selected problem fields in the drilling, turning and milling processes, solutions for creating geometry through machining methods and for analyzing the producibility of 3D CAD models will be presented. Through the implementation of the methods and the development of a special machining-focused environment in the 3D CAD system, the design engineer will be given the ability to align the product modeling process with design guidelines and project-specific manufacturing and economic constraints. By using special methods of knowledge-based design engineering (KBE) and adapted web technologies (Webservice), the geometric information which is bundled in a production-focused form feature will be supplemented with additional technological parameters, such as tools, tool parameters, tool paths and necessary manufacturing operations (e.g. roughing and finishing). For more complex geometrical features, surface-based modeling methods for the design of three-dimensional and production compliant tool-movement envelopes will be provided. These increased-value, production-oriented features are the basis for the cost-estimation in the design phase and for the coupling of the CAD and CAM environments. As a result, the manufacturing-relevant data and information will be extracted by the CAM environment so that the production operations for each step can be determined in a simple manner. This approach results in a complete chain between the design engineering and production departments and can improve the quality of the CAD-CAM information exchange

Aeronautical engineering: A continuing bibliography with indexes (supplement 291)

This bibliography lists 757 reports, articles, and other documents introduced into the NASA scientific and technical information system in May. 1993. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics