Improving the dynamic stability of a workpiece dominated turning process using an adaptronic tool holder

In this contribution, inside turning of a thin-walled cylinder is investigated in simulation. Self-excited vibrations can arise due to repeated cutting of the same surface, that lead to instability. A flexible multibody system model of the system is the basis for a subsequent analysis of the stability of the process. Stability analysis is done using an approximation as a time-discrete system via the semi-discretization method. An adaptronic turning chisel comprising a piezo actuator and sensors is then used in combination with different control concepts to improve the stability of the process. The effectiveness of the different strategies is compared based on the influence on the stability charts. A classic H_∞ controller based on a model of the coupled system of workpiece and tool can only yield some improvements, when an additional measurement of the workpiece displacement is added. Incorporating knowledge on the cutting process coupling workpiece and tool using a gain scheduled H_∞ controller allows further improvements. However, robustness with respect to model uncertainties, notably concerning the force law, remains an issue.     

An approach for the coupled simulation of machining processes using multibody system and smoothed particle hydrodynamics algorithms

The prediction accuracy of a simulation method is limited by its theoretical background. This fact can lead to disadvantages regarding the simulation quality when investigating systems of high complexity, e.g. containing components showing a fairly different behavior. To overcome this limitation, co-simulation approaches are used more and more, combining the advantages of different simulation disciplines. That is why we propose a new strategy for the dynamic simulation of cutting processes. The method couples Lagrangian particle methods, such as the smoothed particle hydrodynamics (SPH) method, and multibody system (MBS) tools using co-simulations. We demonstrate the capability of the new approach by providing simulation results of an orthogonal cutting process and comparing them with experimental data.     

On-line Determination of Particle Size Distribution during the manufacture of compound feed

Experimental investigations were carried out with mainly a Mogensen-Sizer, compared with test screening and additionally laser diffraction and light extinction, in order to check the qualification for on-line determination of particle size distribution under the specific conditions of feed milling. The different components of compound feed, the degree of milling, the difference in measured particle characteristics and the possibility of sample dispersion affect the comparability of the results. The results show that laser diffraction is a manysided method with accurate recording of the distribution. The modified Mogensen-Sizer can be a robust low-price alternative if the control of selected distribution parameters is sufficient.     

Structural Principles for Anion‐Deficient,Fluorite‐Related Superstructures in the Zirconia‐Scandia System

The concept of the coordination defect (CD) was used recently by Bevan and Martin [6] to describe the fluorite‐related superstructures of the intermediate Pr/Tb oxides. The CD is an octahedron of corner‐shared OM_4/8 tetrahedra enclosing a □M_4/8 tetrahedron, where □ represents an oxygen vacancy. Various linkages of CDs can define a polyhedral prism with contents appropriate to the phase composition, and this is designated the “structural motif”. The identical, parallel top and bottom planes of this prism are the “motif plane”. This concept is now extended to explore the structures of the ordered phases, delta, gamma and beta, which occur in the zirconia‐scandia system, the respective formulae being Zr₃Sc₄O₁₂, Zr₁₀Sc₄O₂₆ and Zr₄₈Sc₁₄O₁₁₇ to Zr₅₀Sc₁₂O₁₁₈. It is shown that the motif plane is the same in each of the known structures (delta and gamma), thus defining the close relationship between them. Possible models for the as‐yet unknown structure of the beta phase, in which this same motif plane occurs, can then be proposed.     

Komplexchemie P‐reicher Phosphane und Silylphosphane. XXV. Bildung und Struktur des [{cyclo‐P3(PtBu2)3}{Ni(CO)2}{Ni(CO)3}]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXV. Formation and Structure of [{ cyclo ‐P₃(P^tBu₂)₃}{Ni(CO)₂}{Ni(CO)₃}] ^tBu₂P–P=P(R)^tBu₂ (R = Br, Me) reacts with [Ni(CO)₄] yielding [{cyclo‐P₃(P^tBu₂)₃}{Ni(CO)₂}{Ni(CO)₃}]. The two cis‐^tBu₂P substituents of the cyclotriphosphane, which results from the trimerization of the phosphinophosphinidene ^tBu₂P–P, are coordinating to a Ni(CO)₂ unit forming a five‐membered P₄Ni chelate ring. The trans‐^tBu₂P group is linked to a Ni(CO)₃ unit. The compound crystallizes in the orthorhombic space group Pbca (No. 61) with a = 933.30(5), b = 2353.2(1) and c = 3474.7(3) pm.     

Reaktionen von tBu2P–P=P(Me)tBu2 mit (Et3P)2NiCl2 und [{η2‐C2H4}Ni(PEt3)2]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXIII. Reactions of ^tBu₂P–P=P(Me)^tBu₂ with (Et₃P)₂NiCl₂ and [{η²‐C₂H₄}Ni(PEt₃)₂] ^tBu₂P–P=P(Me)^tBu₂ ( 1 ) forms with (Et₃P)₂NiCl₂ ( 2 ) and Na(Nph) the [μ‐(1,3 : 2,3‐η‐^tBu₂P₄^tBu₂){Ni(PEt₃)Cl}₂] ( 3 ) as main product. Using Na/Hg instead as reducing agent the Ni⁰ compounds [{η²‐^tBu₂P–P}Ni(PEt₃)₂] ( 4 ), [{η²‐^tBu₂P–P=P–P^tBu₂}Ni(PEt₃)₂] ( 5 ) and [(Et₃P)Ni(μ‐P^tBu₂)]₂ ( 6 ) with four‐membered Ni₂P₂ ring result. [{η²‐C₂H₄}Ni(PEt₃)₂] yields with 1 also 4 . The compounds were characterized by ¹H and ³¹P{¹H} NMR investigations and 3 also by a single crystal X‐ray analysis. It crystallizes triclinic in the space group P 1 with a = 1129.4(2), b = 1256.8(3), c = 1569.5(3) pm, α = 72.44(3)°, β = 70.52(3)° and γ = 74.20(3)°.     

Sb2SmO4Cl,eine erste Antimon‐Seltenerd‐Oxid‐Chlorid‐Verbindung

Sb₂SmO₄Cl, the First Antimony Rare‐Earth Oxide Chloride The new quaternary phase Sb₂SmO₄Cl was prepared by solid‐state reaction of a stoichiometric mixture of SbCl₃, Sb₂O₃, and Sm₂O₃. Sb₂SmO₄Cl is the first antimony rare‐earth oxide chloride. It was characterized by X‐ray powder diffraction, IR‐spectroscopy, mass spectrometry and DTA/TG measurements. The standardenthalpy of formation was derived from heats of solution. The standard entropy were calculated from a low‐temperature measurement of the specific heat capacity.