Air Characteristics in Air Turbine Spindle of Ultra Precision Machines

2010 ◽  
Vol 297-301 ◽  
pp. 396-401
Author(s):  
Mehrdad Vahdati ◽  
E. Azimi ◽  
Ali Shokuhfar
Keyword(s):  
High Speed ◽  
Design Procedure ◽  
Inlet Pressure ◽  
Cylindrical Shape ◽  
Air Inlet ◽  
Wind Turbine System ◽  
Air Turbine ◽  
Ultra Precision ◽  
The One ◽  
Precision Machines

Air Spindles have been used in ultra precision machines for several years due to their advantages such as high speed rotation, low friction, and low vibration, [1]. Air spindles are widely used in these machines for producing precise work pieces. Although, spindles function on a very complicated theoretical basis, [2, 3], their structure is very simple and consists of mainly a rotor and a stator. The rotor/stator could be made of different shapes. A cylindrical shape is the one commonly in use. The spindle designed in this work has a spherical configuration. It has been designed so that it could be moved without application of electric motor and only by a wind turbine system, [4]. The spindle studied in this research uses compressed air for rotor suspension, and has an air turbine for rotating its shaft. A thin air film acts as bearing layer between rotor and stator. In design procedure, operation parameters such as air inlet pressure for turbine, air inlet pressure for bearing, diameter of turbine nuzzles, diameter of bearing nuzzles, clearance between rotor and stator and etc. have been considered, [5]. A prototype spindle has been manufactured using design criteria. The influence of above mentioned parameters have been recognized through experiments.

Disturbance Observers for Rigid Mechanical Systems: Equivalence, Stability, and Design

2002 ◽  
Vol 124 (4) ◽  
pp. 539-548 ◽  
Author(s):  
Erwin Schrijver ◽  
Johannes van Dijk
Keyword(s):  
Disturbance Rejection ◽  
Disturbance Observer ◽  
High Speed ◽  
Design Procedure ◽  
Systematic Design ◽  
Direct Drive ◽  
Robot Tracking ◽  
Feedback Structure ◽  
Drive Systems ◽  
The One

Mechanical (direct-drive) systems designed for high-speed and high-accuracy applications require control systems that eliminate the influence of disturbances like cogging forces and friction. One way to achieve additional disturbance rejection is to extend the usual (P(I)D) controller with a disturbance observer. There are two distinct ways to design, represent, and implement a disturbance observer, but in this paper it is shown that the one is a generalization of the other. A general systematic design procedure for disturbance observers that incorporates stability requirements is given. Furthermore, it is shown that a disturbance observer can be transformed into a classical feedback structure, enabling numerous well-known tools to be used for the design and analysis of disturbance observers. Using this feedback interpretation of disturbance observers, it will be shown that a disturbance observer based robot tracking controller can be constructed that is equivalent to a passivity based controller. By this equivalence not only stability proofs of the disturbance observer based controller are obtained, but it also provides more transparent controller parameter selection rules for the passivity based controller.

A Study on Design of Ultra-Precision Micro-Feed Stage

2006 ◽  
Vol 315-316 ◽  
pp. 131-135
Author(s):  
Q. Zhang ◽  
Ze Sheng Lu
Keyword(s):  
Design Method ◽  
Dynamic Performance ◽  
Design Procedure ◽  
Performance Parameters ◽  
Element Analysis ◽  
Flexure Hinges ◽  
Ultra Precision ◽  
Positioning Technique ◽  
Precision Machines ◽  
Geometrical Dimensions

Ultra-precision positioning technique has become one of the important parts in the development of precision machines. Flexure stage driven by piezoelectric actuator (PZT) has been used widely as micro-feed installation because they have many advantages, such as: driving directly, fine displacement resolution, no friction or spacing. This paper designed a micro-feed stage driven by PZT using clinograph mechanism, analyzed the influence of flexure hinges on the static and dynamic performance of micro-feed stage based on finite element analysis. The design procedure was presented by which we can determine the geometrical dimensions of flexure hinge easily and achieve desired performance parameters of the stage, and the effectiveness of the design method was validated by experiment.

scholarly journals Part-optimized forming by spatially distributed vaporizing foil actuators

2021 ◽  
Author(s):  
Marlon Hahn ◽  
A. Erman Tekkaya
Keyword(s):  
Process Design ◽  
High Speed ◽  
Specific Impulse ◽  
Design Procedure ◽  
Mathematical Optimization ◽  
Starting Point ◽  
Spatially Distributed ◽  
Lower Tool ◽  
A Minor ◽  
Charging Energy

AbstractElectrically vaporizing foil actuators are employed as an innovative high speed sheet metal forming technology, which has the potential to lower tool costs. To reduce experimental try-outs, a predictive physics-based process design procedure is developed for the first time. It consists of a mathematical optimization utilizing numerical forming simulations followed by analytical computations for the forming-impulse generation through the rapid Joule heating of the foils. The proposed method is demonstrated for an exemplary steel sheet part. The resulting process design provides a part-specific impulse distribution, corresponding parallel actuator geometries, and the pulse generator’s charging energy, so that all process parameters are available before the first experiment. The experimental validation is then performed for the example part. Formed parts indicate that the introduced method yields a good starting point for actual testing, as it only requires adjustments in the form of a minor charging energy augmentation. This was expectable due to the conservative nature of the underlying modeling. The part geometry obtained with the most suitable charging energy is finally compared to the target geometry.

scholarly journals Research on aerodynamic characteristics of two-stage axial micro air turbine spindle for small parts machining

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402098437
Author(s):  
Liu Jiang ◽  
Guo Zhiping ◽  
Miao Shujing ◽  
He Xiangxin ◽  
Zhu Xinyu
Keyword(s):  
High Speed ◽  
Aerodynamic Characteristics ◽  
Maximum Efficiency ◽  
Two Stage ◽  
Output Torque ◽  
Air Turbine ◽  
Solid Foundation ◽  
Computational Fluid Dynamics Cfd ◽  
Micro Machine ◽  
Small Parts

In order to meet the requirements of output torque, efficiency and compact shape of micro-spindles for small parts machining, a two-stage axial micro air turbine spindle with an axial inlet and outlet is proposed. Based on the k-ω turbulence model of SST, the flow field and operation characteristics of the two-stage axial micro air turbine spindle were studied using computational fluid dynamics (CFD) combined with an experimental study. We obtained the air turbine spindle under different working conditions of the loss and torque characteristics. When the inlet pressure was 300 KPa, the output speed of the two-stage turbine was 100,000 rpm, 9% higher than that of a single-stage turbine output torque. The total torque reached 6.39 N·mm, and the maximum efficiency of the turbine and the spindle were 42.2% and 32.3%, respectively. Through the research on the innovative structure of the two-stage axial micro air turbine spindle, the overall performance of the principle prototype has been significantly improved and the problems of insufficient output torque and low working efficiency in high-speed micro-machining can be solved practically, which laid a solid foundation for improving the machining efficiency of small parts and reducing the size of micro machine tool.

Development and Experimental Performance Verification of a Magneto-Aerostatic Bearing for Cartridge of Dental Handpieces

2012 ◽  
Author(s):  
Guan-Chung Ting ◽  
Kuang-Yuh Huang ◽  
Keng-Ning Chang
Keyword(s):  
High Speed ◽  
Ball Bearings ◽  
Aerostatic Bearing ◽  
Operation Conditions ◽  
Air Inlet ◽  
Efficient Performance ◽  
Aerostatic Bearings ◽  
Repulsive Forces ◽  
Radial Loading ◽  
Air Film

Bearings for high-speed rotors are the key component of dental handpieces. The friction induced by conventional ball bearings restricts its speed and reduces its efficiency. In order to significantly improve the efficiency of dental handpieces, a mini-type cartridge that integrates a turbine and a spindle with radial aerostatic bearings and axial passive magnetic bearings has been ingeniously designed and realized. Around the rotating spindle, there is a high-pressured air film built up by a pair of radial aerostatic bearings, and magnet rings are applied to create repulsive forces to axially support the rotating spindle. The high-pressured air film comes from the specifically designed separable orifice restrictors, which can be easily and precisely manufactured. Frictionless bearing effect can be achieved by aerostatic principle, and the magnetic principle is applied to create large repulsive force against the axial working force. A tri-directional air inlet is designed to reduce radial loading force of a spindle during working. The modularized form of the magneto-aerostatic bearing allows it to be easily assembled and replaced in the very compact space of a mini-type cartridge. Through analytical simulations with fluid-dynamics software (CFD) and experiments, the magneto-aerostatic bearing is optimized to bring out efficient performance in its limited space. The experiments have verified that its noise level is 15dB lower than the conventional cartridge with ball bearings, and its startup air pressure is reduced from 0.4 bar to 0.1 bar. Under the same operation conditions, the newly developed cartridge with magneto-aerostatic bearings creates twice higher speed than that of the conventional one.

Synthesis of Inertially Compensated Variable-Speed Cams

2003 ◽  
Vol 125 (3) ◽  
pp. 593-601 ◽  
Author(s):  
B. Demeulenaere ◽  
J. De Schutter
Keyword(s):  
High Speed ◽  
Design Procedure ◽  
Variable Speed ◽  
Speed Variation ◽  
Design Choice ◽  
Cam Follower ◽  
Speed Fluctuation ◽  
Novel Design

Traditionally, cam-follower systems are designed by assuming a constant camshaft speed. Nevertheless, all cam-follower systems, especially high-speed systems, exhibit some camshaft speed fluctuation (despite the presence of a flywheel) which causes the follower motions to be inaccurate. This paper therefore proposes a novel design procedure that explicitly takes into account the camshaft speed variation. The design procedure assumes that (i) the cam-follower system is conservative and (ii) all forces are inertial. The design procedure is based on a single design choice, i.e., the amount of camshaft speed variation, and yields (i) cams that compensate for the inertial dynamics for any period of motion and (ii) a camshaft flywheel whose (small) inertia is independent of the period of motion. A design example shows that the cams designed in this way offer the following advantages, even for non-conservative, non-purely inertial cam-follower systems: (i) more accurate camshaft motion despite a smaller flywheel, (ii) lower motor torques, (iii) more accurate follower motions, with fewer undesired harmonics, and (iv) a camshaft motion spectrum that is easily and robustly predictable.

Ultrapräzise Hochgeschwindigkeitsbearbeitung*/Ultra-precision high performance cutting - Part 1: Increasing the surface generation rate using tools with multiple cutting edges and high-speed spindels

2015 ◽  
Vol 105 (06) ◽  
pp. 366-370
Author(s):  
L. Schönemann ◽  
W. Preuß ◽  
O. Riemer ◽  
E. Foremny ◽  
E. Brinksmeier ◽  
...  
Keyword(s):  
High Speed ◽  
High Performance ◽  
Generation Rate ◽  
Surface Generation ◽  
Ultraprecision Machining ◽  
Single Edge ◽  
Ultra Precision ◽  
Optical Freeform Surfaces ◽  
Novel Approaches ◽  
Milling Tools

Die ultrapräzise Fräsbearbeitung ist eine flexible Möglichkeit zur Herstellung optischer Freiformflächen. Aufgrund der hohen Genauigkeitsanforderungen kommen hierbei jedoch zumeist einschneidige Werkzeuge und niedrige Spindeldrehzahlen zum Einsatz. Diese Arbeit zeigt zwei neue Ansätze zur Steigerung der Flächenleistung in der Ultrapräzisionsbearbeitung: den Einsatz thermisch verstellbarer Mehrfachwerkzeuge sowie die Verwendung ultrapräziser Hochgeschwindigkeitsspindeln in Verbindung mit neuen Methoden zur Auswuchtung.   Ultraprecision milling is a flexible process for generating optical freeform surfaces. Due to the tight tolerances of such parts, only single-edge tools and low spindle frequencies are applied. This publication presents two novel approaches to increase the surface generation rate in ultraprecision machining: the use of milling tools with multiple cutting edges that are aligned via a thermomechanical actuator and the application of high speed spindels that require novel approaches for balancing.

Aeroelastic Problems in connection with High-Speed Flight

1956 ◽  
Vol 60 (547) ◽  
pp. 459-475 ◽  
Author(s):  
E. G. Broadbent
Keyword(s):  
Mach Number ◽  
High Speed ◽  
The Other ◽  
Control Surface ◽  
The Past ◽  
Other Hand ◽  
Aerodynamic Derivatives ◽  
Mach Numbers ◽  
The One

SummaryA review is given of developments in the field of aeroelasticity during the past ten years. The effect of steadily increasing Mach number has been two-fold: on the one hand the aerodynamic derivatives have changed, and in some cases brought new problems, and on the other hand the design for higher Mach numbers has led to thinner aerofoils and more slender fuselages for which the required stiffness is more difficult to provide. Both these aspects are discussed, and various methods of attack on the problems are considered. The relative merits of stiffness, damping and massbalance for the prevention of control surface flutter are discussed. A brief mention is made of the recent problems of damage from jet efflux and of the possible aeroelastic effects of kinetic heating.

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