Mecachrome (France)

About: Mecachrome (France) is a company organization based out in Amboise, France. It is known for research contribution in the topics: Machining & Hydrostatic stress. The organization has 14 authors who have published 12 publications receiving 41 citations.

Dynamic Study of Thin Wall Part Turning

Abstract: The numerical simulation of machining process is a key factor in the control of parts machining process. Its development aims at improving the process reliability and reduces the time spent during the process planning stage. In this context, we use a specific time domain simulation allowing modeling the dynamics of a thin wall part turning operation. After having introduced the basics of the proposed approach we present a specific cutting test that has been designed to specifically measure and control the dynamics of the part and the cutting conditions of a finishing toolpath. The influences of the cutting speed and damping coefficient on the chatter occurrence are discussed. In order to better control the simulation uses, an analysis of the simulation parameters influences on the simulated results is proposed.

Transformation Kinetics and Resulting Microstructure in MMC Reinforced with TiC Particles

Abstract: The phase transformation kinetics on cooling and resulting microstructures of steel-based matrix composites (MMC) reinforced with TiC particles by powder metallurgy were studied. In addition, the phase transformation kinetics of the MMC were compared to those of the same steel without TiC and consolidated in the same conditions. The presence of TiC particles strongly favors the diffusive transformations in the steel matrix of the MMC. Different complementary techniques (XRD, SEM, TEM/EDX, atom probe tomography, in situ synchrotron XRD) were performed to analyze the chemical reactivity between TiC particles and the steel powders occurring during consolidation process and further heat treatments. Composition changes in the TiC as well as in the matrix were characterized. The chemical composition after treatment in the TiC particles tends toward the thermodynamic calculations with ThermoCalc. The effect of changes in chemical composition and the role of TiC particles acting as new favorable nucleation sites are discussed in regards to the obtained results.

Method and Device for Manufacturing Turbine Blades

Abstract: The present invention relates to a method and device for manufacturing turbine blades (5; 7; 28; 33) made of a metal alloy. Starting with an aluminium and titanium alloy bar (10; 34) having a simple and/or axisymmetric shape, at least two mutually interlocking blanks (2; 3; 4; 8; 11) are produced in the bar (10; 34) by waterjet cutting (16), and then each one of said blanks (2; 3; 4; 8; 11) thus obtained is machined separately in order to obtain the blades (5; 7; 28; 33) having a final profile.

Device and method for cutting parts consisting of a metal or composite material and parts produced with such a method

Abstract: The invention relates to a device, a method and an assembly of parts produced by cutting in a block B of metal or composite material, following a determined trajectory. The device comprises a guide (3) forming said trajectory and a support (chain 9) mounted in the guide in a sliding manner, comprising a lateral blank (23) provided with at least one cutting plate (24) comprising a protruding cutting edge (25) arranged so as to carry out the cutting in a normal direction (26) in relation to the blank.

In Situ Structural Evolution of Steel-Based MMC by High Energy X-Ray Diffraction and Comparison with Micromechanical Approach

Abstract: In situ high energy X-ray diffraction synchrotron was used to provide direct analysis of the transformation sequences in steel-based matrix composite (MMC) reinforced with TiC particles. Evolution of the phase fractions of the matrix and TiC particles as well as the mean cell parameters of each phase were determined by Rietveld refinement from high energy X-ray diffraction (ID15B, ESRF, Grenoble, France). In addition, some peaks were further analysed in order to obtain the X-ray strain during the cooling step. Non-linear strain evolutions of each phase are evidenced, which are either associated with differences in the coefficient of thermal expansion (CTE) between matrix and TiC particle or to the occurrence of phase transformation. Micromechanical calculations were performed through the finite element method to estimate the stress state in each phase and outline the effects of differences in CTE and of volume change associated with the matrix phase transformation. The calculated results led to a final compressive hydrostatic stress in the TiC reinforcement and tensile hydrostatic stress in the matrix area around the TiC particles. Besides, the tendencies measured from in situ synchrotron diffraction (mean cell parameters) matched with the numerical estimates.