Determination of Force Parameters for Milling Simulations by Combining Optimization and Simulation Techniques

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Dennis Freiburg ◽  
Rouven Hense ◽  
Petra Kersting ◽  
Dirk Biermann
Keyword(s):  
Process Parameters ◽  
Degrees Of Freedom ◽  
Machining Process ◽  
Limiting Factor ◽  
Force Model ◽  
Process Forces ◽  
Wide Range ◽  
Optimization And Simulation

Milling is a machining process in which material removal occurs due to the rotary motion of a cutting tool relative to a typically stationary workpiece. In modern machining centers, up to and exceeding six degrees of freedom for motion relative to the tool and workpiece are possible, which results in a very complex chip and force formation. For the process layout, simulations can be used to calculate the occurring process forces, which are needed, e.g., for the prediction of surface errors of the workpiece, or for tool wear and process optimization examinations. One limiting factor for the quality of simulation results is the parametrization of the models. The most important parameters for milling simulations are the ones that calibrate the force model, as nearly every modeled process characteristic depends on the forces. This article presents the combination of a milling simulation with the Broyden–Fletcher–Goldfarb–Shanno (BFGS) optimization algorithm for the fast determination of force parameters that are valid for a wide range of process parameters. Experiments were conducted to measure the process forces during milling with different process parameters. The measured forces serve as basis for tests regarding the quality of the determined force parameters. The effect of the tool runout on the optimization result is also discussed, as this may have significant influence on the forces when using tools with more than one tooth. The article ends with a conclusion, in which some notes about the practical application of the algorithm are given.

Last-Verlagerungsverhalten von Kugelgewindetrieben/Load displacement behavior on ball screws

2020 ◽  
Vol 110 (05) ◽  
pp. 295-298
Author(s):  
Christian Brecher ◽  
Florian Kneer ◽  
Stephan Neus
Keyword(s):  
Machine Tools ◽  
Machining Process ◽  
Ball Screw ◽  
Elastic Displacement ◽  
Technical Paper ◽  
Process Forces ◽  
Displacement Behavior ◽  
Load Displacement ◽  
Machine Structure

Die axiale Steifigkeit von Kugelgewindetrieben ist wesentlich für das Betriebsverhalten von Werkzeugmaschinen. Während der Bearbeitung werden die Prozesskräfte über den Kugelgewindetrieb in die Maschinenstruktur übertragen. Kugelgewindetriebe tragen daher maßgeblich zur Qualität und Produktivität von Werkzeugmaschinen bei. Dieser Beitrag beschreibt eine Methode zur messtechnischen, prüfstandsgebundenen Ermittlung des Last-Verlagerungsverhaltens an Kugelgewindetrieben.   The axial elastic displacement of ball screws are essential for the operating behavior of machine tools. During machining, process forces must be transmitted to the machine structure via the ball screw. Ball screws contribute significantly to the quality and productivity of machine tools. This technical paper describes a methodology for the metrological determination of the load-displacement behavior on ball screws.

scholarly journals Influence of Elastomer Layers in the Quality of Aluminum Parts on Finishing Operations

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 289 ◽  
Author(s):  
Antonio Rubio-Mateos ◽  
Asuncion Rivero ◽  
Eneko Ukar ◽  
Aitzol Lamikiz
Keyword(s):  
Process Parameters ◽  
Feed Rate ◽  
Cutting Speed ◽  
Milling Process ◽  
Machining Process ◽  
Butadiene Rubber ◽  
Compression Tests ◽  
Compressive Behavior ◽  
Finishing Processes

In finishing processes, the quality of aluminum parts is mostly influenced by static and dynamic phenomena. Different solutions have been studied toward a stable milling process attainment. However, the improvements obtained with the tuning of process parameters are limited by the system stiffness and external dampers devices interfere with the machining process. To deal with this challenge, this work analyzes the suitability of elastomer layers as passive damping elements directly located under the part to be machined. Thus, exploiting the sealing properties of nitrile butadiene rubber (NBR), a suitable flexible vacuum fixture is developed, enabling a proper implementation in the manufacturing process. Two different compounds are characterized under axial compression and under finishing operations. The compression tests present the effect of the feed rate and the strain accumulative effect in the fixture compressive behavior. Despite the higher strain variability of the softer rubber, different milling process parameters, such as the tool feed rate, can lead to a similar compressive behavior of the fixture regardless the elastomer hardness. On the other hand, the characterization of these flexible fixtures is completed over AA2024 floor milling of rigid parts and compared with the use of a rigid part clamping. These results show that, as the cutting speed and the feed rate increases, due to the strain evolution of the rubber, the part quality obtained tend to equalize between the flexible and the rigid clamping of the workpiece. Due to the versatility of the NBR for clamping different part geometries without new fixture redesigns, this leads to a competitive advantage of these flexible solutions against the classic rigid vacuum fixtures. Finally, a model to predict the grooving forces with a bull-nose end mill regardless of the stiffness of the part support is proposed and validated for the working range.

scholarly journals Determination of prioritization for maintenance of the upper structure of truss bridge

2019 ◽  
Vol 276 ◽  
pp. 01036 ◽  
Author(s):  
Heni Fitriani ◽  
M. Ade Surya Pratama ◽  
Yakni Idris ◽  
Gunawan Tanzil
Keyword(s):  
Poor Quality ◽  
Truss Bridges ◽  
Vehicle Load ◽  
Bridge Maintenance ◽  
Wide Range ◽  
Maintenance Systems ◽  
Truss Bridge ◽  
Hierarchy Process

Bridge maintenance is one of the major issues of infrastructure problems. Deterioration of a bridge’s structure will continuously increase without proper maintenance. This condition will adversely affect the service life of a bridge. Moreover, the damage will also have a direct impact on structural and functional failure of the bridge. This paper aims at identifying the damages of truss bridges and determining the most significant criteria and sub-criteria used in prioritizing bridge maintenance. Analytical Hierarchy Process (AHP) was used to assess the most important criteria that give significant weight to bridge maintenance analysis. The objects of research were nine truss bridges with a wide range of types and levels of damage. It was found that there were approximately 900 m' of components damaged at the railing of Baruga Bridge and 227 m' truss damages due to poor quality of the galvanized paint. Furthermore, based on the analysis, the most significant criteria were the level of damage (27.6%), the technical aspects (25.7%), the finance (21%), the vehicle load (13.6%) and the resources (12%). The results of this research showed important findings in determining the priority scales for bridge repair and maintenance systems.

Evaluation and Optimum Design of Parallel Manipulators Having Defined Workspace

2000 ◽  
Author(s):  
Jürgen Schönherr
Keyword(s):  
Optimum Design ◽  
Degrees Of Freedom ◽  
Parallel Manipulators ◽  
Parallel Structure ◽  
Transmission Quality ◽  
6 Degrees Of Freedom ◽  
Kinematic Optimization ◽  
Method Of Design

Abstract The condition of the Jacobian characterizes the transmission quality of manipulators and is used in this paper for the determination of the dimensions of manipulators having best mobility for a defined workspace. Typical planar and spatial manipulators of parallel structure and having 3 or 6 degrees of freedom are used to demonstrate the method of design used. Manipulators having identical degrees of freedom and workspaces and different structures, including those having fixed or variable leg lengths, are compared with respect to their mobility. The computing program developed for the purpose of optimum design performs the kinematic optimization of machines and manipulators of any structure.

Shell strength of Nautilus as a depth limiting factor

Paleobiology ◽  
1977 ◽  
Vol 3 (1) ◽  
pp. 83-89 ◽  
Author(s):  
W. Bruce Saunders ◽  
Deborah A. Wehman
Keyword(s):  
External Pressure ◽  
Limiting Factor ◽  
Strain Gages ◽  
Shell Material ◽  
Nautilus Pompilius ◽  
Septal Thickness ◽  
Microstructural Inhomogeneity ◽  
Wide Range ◽  
Depth Ranges

Implosion of 47 epoxy-sealed shells of Nautilus pompilius indicates that very young shells (20-30 mm diameter at last septum) can withstand 136 atm pressure (= 1360 m equivalent depth), but intermediate and mature shells (30-145 mm diameter) implode at approximately 30–70 atm (= 300–700 m). Strain gages attached to the shells during implosion tests show that the flank and venter are compressed by external pressure, but the septum undergoes tension and structurally should be the most vulnerable to hydrostatic pressure. Overall shell strength is substantially less than reported values of tensile strength (approximately 364 atm) and compressive strength (approximately 1561 atm) of the constituent shell material, nacre. Shell strength as a depth limiting factor appears to be controlled by shell and septal architecture and by stress concentrators such as flaws and microstructural inhomogeneity. The wide range in implosion values and lack of strong correlation between such parameters as septal thickness and implosion pressure indicate that determination of depth ranges for fossil cephalopods may be difficult.

scholarly journals Development of a Device for Staged Determination of Water Activity and Moisture Content

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 881 ◽  
Author(s):  
Carlo Tiebe ◽  
Marc Detjens ◽  
Annika Fechner ◽  
Stefanie Sielemann ◽  
Andreas Lorek ◽  
...  
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Bound Water ◽  
Free Water ◽  
Characteristic Parameter ◽  
Industrial Applications ◽  
Wide Range ◽  
Temperature Equilibrium

Moisture content and water activity are important parameters for quality characterizationof products like bulk materials, powders, granules. Thus, an exact determination is necessarilyrequired in a wide range of industrial applications. Moisture of materials is the content ofnon-chemically bound water in a solid or liquid. Water activity (aw) is a characteristic/parameter ofthe non-chemically bound (“free”) water in materials and is measured as humidity over asolid/liquid surface at constant temperature (equilibrium moisture content). It is an importantparameter to characterize the quality of e.g., pharmaceutical and food products. In ourcontribution, we present the developed MOISHUM device for staged determination of wateractivity and moisture content of liquid and solid materials.

scholarly journals Impacto, em curto prazo, dos antibióticos amoxicilina e doxiciclina na qualidade microbiana de um Latossolo Vermelho-amarelo (Short-term impact of the antibiotics amoxicillin and doxycycline on the microbial quality of a Red-yellow Latosol)

2019 ◽  
Vol 12 (4) ◽  
pp. 1340
Author(s):  
Luiz Gustavo Paulon Rezende ◽  
Márcia Matiko Kondo ◽  
Rogério Melloni
Keyword(s):  
Microbial Activity ◽  
Soil Microorganisms ◽  
Microbial Quality ◽  
Environmental Matrices ◽  
Short Term ◽  
Wide Range ◽  
Keywords Antibiotics ◽  
The Impact

Concentrações residuais de antibióticos de uso compartilhado pela terapia médica humana e veterinária são cada vez mais frequentes nos mais variados tipos de matrizes ambientais; no entanto, pouco se sabe sobre o impacto que esses fármacos podem acarretar aos microrganismos do solo. Sendo assim, perturbações relacionadas à exposição da microbiota de um latossolo vermelho-amarelo brasileiro a dois antibacterianos, a amoxicilina (AMOX) e a doxiciclina (DOX), foram investigadas por meio da determinação de atividade (mg CO2) e biomassa (Cmic) microbianas, juntamente com o quociente metabólico (qCO2), em amostras de solo que receberam as seguintes concentrações desses compostos: 0,03, 0,3, 3,0, 30 e 300 mg L-1. Os resultados mostraram diferentes efeitos sobre a microbiota e de forma específica para cada antibiótico. A AMOX mostrou-se mais impactante para os microrganismos do solo, com redução da biomassa e aumento do qCO2, enquanto que a DOX reduziu a atividade microbiana, mas sem efeito na biomassa e qCO2.A B S T R A C TThe residual concentrations of antibiotics used by human and veterinary medical therapy are increasingly common in a wide range of environmental matrices, nevertheless little is known about the impact of these drugs on to the soil microorganisms. Therefore, disturbances related to the exposure of the microbiota of a Brazilian Red-yellow Latosol to two antibacterials, amoxicillin (AMOX) and doxycycline (DOX), were investigated through the determination of the microbial activity (mg CO2) and biomass (Cmic), among with the metabolic quotient (qCO2), using soil samples spiked with: 0,03, 0,3, 3,0, 30 and 300 mg L-1 of each drug. The results showed different effects on the microbiota and in a specific way for each antibiotic. The AMOX showed higher impact impacting for the soil microorganisms, with reduction of the biomass and increase of the qCO2, whereas the DOX reduced the microbial activity, but showed no effect in the biomass and qCO2.Keywords: Antibiotics. Amoxicillin. Doxycycline. Bioindicators. Latosols.

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