Predicting the Effect of Vibration on Machining Distortion in High-Speed Milling Aerospace Monolithic Components

2010 ◽  
Author(s):  
Q. H. Song ◽  
X. Ai ◽  
Z. Q. Liu
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Coordinate Measuring Machine ◽  
Stable Case ◽  
Machining Distortion ◽  
Stable Conditions ◽  
Unstable Case ◽  
Measuring Machine ◽  
The Stability ◽  
Monolithic Components

Based on the stability lobe diagram of two degrees of freedom milling system obtained by using the numerical method, two kinds of cutting conditions (stable and unstable) are selected to perform the cutting tests of aeronautical monolithic components. Cutting distortion and secular distortion are measured and analyzed by using the MISTRAL 775 coordinate measuring machine (CMM), respectively. Influences of chatter on machining distortion are investigated. It is shown that, both machining distortion and secular distortion are smaller in stable case; in unstable case, machining distortion is also smaller, while secular distortion is very large, and torsion occurs in the workpiece end with larger box. Therefore, workpiece need be machined in stable conditions for subsequent assembly work, especially aeronautical monolithic components.

A Technique for Enhancing Machine Tool Accuracy by Transferring the Metrology Reference From the Machine Tool to the Workpiece

2006 ◽  
Vol 129 (3) ◽  
pp. 636-643 ◽  
Author(s):  
Bethany A. Woody ◽  
K. Scott Smith ◽  
Robert J. Hocken ◽  
Jimmie A. Miller
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
High Speed ◽  
Large Scale ◽  
Thermal Environment ◽  
Coordinate Measuring Machine ◽  
Shop Floor ◽  
Finished Part ◽  
Measuring Machine ◽  
Monolithic Components

High-speed machining (HSM) has had a large impact on the design and fabrication of aerospace parts and HSM techniques have been used to improve the quality of conventionally machined parts as well. Initially, the trend toward HSM of monolithic parts was focused on small parts, where existing machine tools have sufficient precision to machine the required features. But, as the technology continues to progress, the scale of monolithic parts has continued to grow. However, the growth of such parts has become limited by the inability of existing machines to achieve the tolerances required for assembly due to the long-range accuracy and the thermal environment of most machine tools. Increasing part size without decreasing the tolerances using existing technology requires very large and very accurate machines in a tightly controlled thermal environment. As a result, new techniques are needed to precisely and accurately manufacture large scale monolithic components. Previous work has established the fiducial calibration system (FCS), a technique, which, for the first time provides a method that allows for the accuracy of a coordinate measuring machine (CMM) to be transferred to the shop floor. This paper addresses the range of applicability of the FCS, and provides a method to answer two fundamental questions. First, given a set of machines and fiducials, how much improvement in precision of the finished part can be expected? And second, given a desired precision of the finished part, what machines and fiducials are required? The achievable improvement in precision using the FCS depends on a number of factors including, but not limited to: the type of fiducial, the probing system on the machine and CMM, the time required to make a measurement, and the frequency of measurement. In this paper, the sensitivity of the method to such items is evaluated through an uncertainty analysis, and examples are given indicating how this analysis can be used in a variety of cases.

Evaluation of Parts Produced by a Novel Additive Manufacturing Process

2013 ◽  
Vol 315 ◽  
pp. 63-67 ◽  
Author(s):  
Muhammad Fahad ◽  
Neil Hopkinson
Keyword(s):  
Additive Manufacturing ◽  
Rapid Prototyping ◽  
Manufacturing Process ◽  
High Speed ◽  
Three Dimensional ◽  
Coordinate Measuring Machine ◽  
Layer By Layer ◽  
Nylon 12 ◽  
Measuring Machine ◽  
End Use

Rapid prototyping refers to building three dimensional parts in a tool-less, layer by layer manner using the CAD geometry of the part. Additive Manufacturing (AM) is the name given to the application of rapid prototyping technologies to produce functional, end use items. Since AM is relatively new area of manufacturing processes, various processes are being developed and analyzed for their performance (mainly speed and accuracy). This paper deals with the design of a new benchmark part to analyze the flatness of parts produced on High Speed Sintering (HSS) which is a novel Additive Manufacturing process and is currently being developed at Loughborough University. The designed benchmark part comprised of various features such as cubes, holes, cylinders, spheres and cones on a flat base and the build material used for these parts was nylon 12 powder. Flatness and curvature of the base of these parts were measured using a coordinate measuring machine (CMM) and the results are discussed in relation to the operating parameters of the process.The result show changes in the flatness of part with the depth of part in the bed which is attributed to the thermal gradient within the build envelope during build.

scholarly journals Effect of Horizontal and Vertical Magnetic Fields on Rayleigh?Taylor Instability

1968 ◽  
Vol 21 (6) ◽  
pp. 923 ◽  
Author(s):  
RC Sharma ◽  
KM Srivastava
Keyword(s):  
Magnetic Fields ◽  
General Equation ◽  
Taylor Instability ◽  
Combined Effect ◽  
Physical Situation ◽  
Stable Case ◽  
Unstable Case ◽  
Rayleigh Taylor Instability ◽  
The Stability ◽  
Superposed Fluids

A general equation studying the combined effect of horizontal and vertical magnetic fields on the stability of two superposed fluids has been obtained. The unstable and stable cases at the interface (z = 0) between two uniform fluids, with both the possibilities of real and complex n, have been. separately dealt with. Some new results are obtained. In the unstable case with real n, the perturbations are damped or unstable according as 2(k'-k~L2)_(<X2-<Xl)k is> or < 0 under the physical situation (35). In the stable case, the perturbations are stable or unstable according as 2(k2_k~L2)+(<Xl-<X2)k is > or < 0 under the same physical situation (35). The perturbations become unstable if HIlIH 1- (= L) is large. Both the cases are also discussed with imaginary n.

Investigation of Gyroscopic Effect on the Stability of High Speed Micromilling via Bifurcation Analysis

2021 ◽  
Vol 5 (4) ◽  
pp. 130
Author(s):  
Rinku K. Mittal ◽  
Ramesh K. Singh
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Multistep Method ◽  
Gyroscopic Effect ◽  
High Rotational Speed ◽  
Micro Tool ◽  
The Stability ◽  
Delay Differential ◽  
Stability Limits ◽  
Micro Tools

Catastrophic tool failure due to the low flexural stiffness of the micro-tool is a major concern for micromanufacturing industries. This issue can be addressed using high rotational speed, but the gyroscopic couple becomes prominent at high rotational speeds for micro-tools affecting the dynamic stability of the process. This study uses the multiple degrees of freedom (MDOF) model of the cutting tool to investigate the gyroscopic effect in machining. Hopf bifurcation theory is used to understand the long-term dynamic behavior of the system. A numerical scheme based on the linear multistep method is used to solve the time-periodic delay differential equations. The stability limits have been predicted as a function of the spindle speed. Higher tool deflections occur at higher spindle speeds. Stability lobe diagram shows the conservative limits at high rotational speeds for the MDOF model. The predicted stability limits show good agreement with the experimental limits, especially at high rotational speeds.

scholarly journals Simulation analysis of efficiency and stability for vehicle’s ABS control on combined steering and braking maneuvers

2019 ◽  
Vol 272 ◽  
pp. 01024 ◽  
Author(s):  
Feng YU ◽  
Jun XIE
Keyword(s):  
High Speed ◽  
Control Algorithm ◽  
Degrees Of Freedom ◽  
Simulation Analysis ◽  
Stability Control ◽  
Vehicle Stability ◽  
Slip Ratio ◽  
Braking Performance ◽  
Braking System ◽  
The Stability

Eight degrees of freedom vehicle model was established. Using the method of fuzzy control, the ABS control algorithm was designed based on slip ratio. Simulation analysis was done at speed of 15m/s, 20m/s, 25m/s under turning braking. The results show that the vehicle braking performance and vehicle stability at middle or low speed was improved by using the ABS controller, but qualitative analysis shows that phenomenon of vehicle instability was appeared at high-speed conditions. The turning braking stability under ABS controller was judged quantificationally by the stability judging formula. The results show that the requirements of stability control could not meet with only Anti-lock Braking System.

scholarly journals A “Double Accuracy Theory” and Experimental Research on Precision Grinding

2020 ◽  
Vol 10 (6) ◽  
pp. 2030
Author(s):  
Lai Hu ◽  
Yipeng Li ◽  
Jun Zha ◽  
Yaolong Chen
Keyword(s):  
High Speed ◽  
Coordinate Measuring Machine ◽  
Precision Grinding ◽  
Machined Parts ◽  
Accuracy Theory ◽  
Machine Theory ◽  
Ultra Precision ◽  
Measuring Machine ◽  
Grinding Machine ◽  
Multi Body

In the global machining industry, ultra-precision/ultra-high-speed machining has become a challenge, and its requirements are getting higher and higher. The challenge of precision grinding lies in the difficulty in ensuring the various dimensions and geometric accuracy of the final machined parts. This paper mainly uses the theory of a multi-body system to propose a “double accuracy” theory of manufacturing and measurement. Firstly, the grinding theory with an accuracy of 0.1 μm and the precision three-coordinate measuring machine theory with an accuracy of 0.3 μm are deduced. Secondly, the two theories are analyzed. Aiming to better explain the practicability of the “double accuracy” theory, a batch of motorized spindle parts is processed by a grinding machine. Then the precision three-coordinate measuring machine is used to measure the shape and position tolerances such as the roundness, the squareness, the flatness, and the coaxiality. The results show that the reached roundness of part A and B is 5 μm and 0.5 μm, the squareness is 3 μm and 4.5 μm, and the coaxiality tolerance is 1.2 μm, respectively.

Numerical and Experimental Investigation of the CeCOST Swirl Burner

2018 ◽  
Author(s):  
Erdzan Hodzic ◽  
Senbin Yu ◽  
Arman Ahamed Subash ◽  
Xin Liu ◽  
Xiao Liu ◽  
...  
Keyword(s):  
High Speed ◽  
Swirling Flow ◽  
Combustion Process ◽  
Stability Limit ◽  
Swirl Burner ◽  
Current Configuration ◽  
Stable Case ◽  
Eddy Simulation ◽  
Computational Fluid Dynamics Cfd ◽  
The Stability

Clean technology has become a key feature due to increasing environmental concerns. Swirling flows, being directly associated with combustion performance and hence minimized pollutant formation, are encountered in most propulsion and power-generation combustion devices. In this study, the development process of the conceptual swirl burner developed at the Swedish National Centre for Combustion and Technology (CeCOST), is presented. Utilizing extensive computational fluid dynamics (CFD) analysis, both the lead time and cost in manufacturing of the different burner parts were significantly reduced. The performance maps bounded by the flashback and blow-off limits for the current configuration were obtained and studied in detail using advanced experimental measurements and numerical simulations. Utilizing high speed OH-chemiluminescence, OH/CH2O-PLIF and Large Eddy Simulation (LES), details of the combustion process and flame-flow interaction are presented. The main focus is on three different cases, a stable case, a case close to blow-off and flashback condition. We show the influence of the flame on the core flow and how an increase in swirl may extend the stability limit of the anchored flame in swirling flow burners.

A Calibration Method for a Three-Degrees-of-Freedom Parallel Manipulator with a Redundant Passive Chain

2012 ◽  
Vol 162 ◽  
pp. 171-178 ◽  
Author(s):  
Takaaki Oiwa ◽  
Harunaho Daido ◽  
Junichi Asama
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Least Squares Method ◽  
Coordinate Measuring Machine ◽  
Calibration Method ◽  
Displacement Sensor ◽  
Measurement Experiment ◽  
Measuring Machine ◽  
Measured Length ◽  
Three Degrees Of Freedom

This paper deals with parameter identification for a three-degrees-of-freedom (3-DOF) parallel manipulator, based on measurement redundancy. A redundant passive chain with a displacement sensor connects the moving stage to the machine frame. The passive chain is sequentially placed in three directions at approximately right angles to one another to reliably detect the motion of the stage. Linear encoders measure changes in lengths of the passive chain and the three actuated chains of the manipulator during traveling of the moving stage. Comparison between the measured length and the length calculated from forward kinematics of the 3-DOF manipulator reveals a length error of the passive chain. The least-squares method using a Jacobian matrix corrects 27 kinematic parameters so that the length errors of the passive chain are minimized. The above calculations were accomplished in both numerical simulations and experiments employing a coordinate measuring machine based on the parallel manipulator. Moreover, a length measurement simulation of gauge block measurement and a measurement experiment using the measuring machine were performed to verify the identified parameters.

VERNE - a five-axis parallel kinematics milling machine

2005 ◽  
Vol 219 (3) ◽  
pp. 327-336 ◽  
Author(s):  
M Terrier ◽  
M Giménez ◽  
J-Y Hascoët
Keyword(s):  
High Speed ◽  
Experimental Approach ◽  
Coordinate Measuring Machine ◽  
Direct Consequence ◽  
Numerical Control ◽  
Parallel Kinematics ◽  
High Speed Milling ◽  
Axis Parallel ◽  
Measuring Machine ◽  
Five Axis

Ten years ago a new kind of machine tool was presented in Chicago, based on parallel kinematics architectures. Since then, many of these parallel kinematics machines (PKMs) have been developed around the world. Their main interest lies in their high dynamic characteristics, which could help in going faster in high-speed milling. In order to develop high-speed milling on PKM tools and to highlight their potentialities, the French laboratory IRCCyN is now equipped with the VERNE. This PKM tool has been developed by the Spanish company Fatronik. However, the high-speed milling production process is a complex task, in which a great number of parameters influence the final precision of the part and the productivity of the machine. For example, the NC (numerical control) and computer-aided manufacturing (CAM) parameters (feed forward, milling strategies, etc.), the piece geometry, the machine structure, the tool, etc., have a direct consequence on the final part. Hence, a method has been developed in order to check the capability of the machine (either serial or parallel) in milling, which relies on two approaches. The first one is an experimental approach (either using a coordinate measuring machine or acquiring the output axis encoders), while the second one is a simulated approach. After introducing the kinematics of the VERNE, the experimental approach performed so far will be presented.

On the High-Speed Porpoising Instability of a Prismatic Hull

1984 ◽  
Vol 28 (02) ◽  
pp. 77-89 ◽  
Author(s):  
Peter R. Payne
Keyword(s):  
Skin Friction ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Transient Solution ◽  
Delta Wings ◽  
Closed Form Solutions ◽  
Wetted Area ◽  
The Stability ◽  
Transient Forces ◽  
Vertical Impact

Simple closed-form solutions are obtained for the steady-state and transient forces and moments on a prismatic hull at speeds high enough for hydrostatic forces to be negligible and the chines to be above the undisturbed water surface ("chines dry"). We first show that this solution can be transformed to get the correct results for other hydrodynamic problems, such as the vertical impact of a wedge, a slender foil, or the two-dimensional planing of a flat plate. We then show that the full transient solution is essentially identical with Ribner's [1]2 equations for delta wings, except for terms which depend on the reduction in wetted width with heave. These results are employed to study the stability of such a hull on the assumption that only heave and pitch degrees of freedom are important, following the reasoning of Per̂ing [2]. In contradistinction to all four previous studies [2–5], the effect of skin friction is included and is found to be very powerful. If the center of gravity is above the centroid of the wetted area (which it generally is), then the effect of skin friction is stabilizing.

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