Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Journal of Machine Engineering

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

A new strategy of tool path planning based on hydrodynamic data to machine marine propeller

Breteau T., Damay T., Duc E., Hascoët J.-Y.

Journal of Machine Engineering

2009

Vol. 9, No. 1

29--40

Marine propellers are complex surfaces that are usually machined with a perfect roughness in order not to disturb the theoretical flow. Because this requirement is penalizing from a manufacturing point of view, the global objective of the study is to propose an approach in which the machining parameters are linked to functional properties of the blade in order to remove the polishing phase. To reach this objective, hydrodynamic data are used: streak lines, that are computed during the propeller design phase, characterize the fluid behavior at the close vicinity of the blade. Those lines, which are theoretically continuous at the leading edge, turn out to be discontinuous, due to the computing method. To be consistent with the fluid behavior as much as possible, the idea presented in the paper is to compose a continuous trajectory, especially at the leading edge, to mill the surface. Thus, an algorithm is developed to plan tool paths which are smoothed at leading edge using Bezier curves. Moreover, this algorithm allows to quantify the cusp height at the leading edge to avoid a drop in performance using criteria linked to the dynamical behavior of a five axis machine tool. In this work, a strategy is developed and enables multiaxial milling of a blade surface by using geometric and hydrodynamic data and by respecting the associated constraints.

Machining performance optimization of Parallel Kinematic Machines tools with regard to their anisotropic behaviour

Pateloup S., Bonnemains T., Chanal H., Bouzgarrou B. C., Duc E., Ray P.

Journal of Machine Engineering

2008

Vol. 8, No. 4

13--24

Today, Parallel Kinematic Machines tools (PKMs) appear in automotive and aeronautic industries. These machines allow a benefit of productivity due to their higher kinematics performances than Serial Kinematic Machines tools (SKMs). However, their machining accuracy is lower. Moreover, the compensation of the defects which penalizes the machined parts quality is difficult due to their anisotropic behaviour. Thus, this article deals with the development of methods improving the machined parts quality and the productivity. In order to improve parts quality, the static behaviour of the machine structure is considered with a model taking into account joints and legs compliances. Then, it allows determining a static workspace. About the productivity, the improvement of kinematics performances is performed through an optimization work of the non productive tool path between cutting operations. The computed tool path must verify a minimum time constraint and avoid collisions between the tool and the machined part. All the methods are illustrated with the PKM Tripteor X7 developed by PCI.