Current Monitoring of Field Controlled DC Spindle Drives

1986 ◽  
Vol 108 (4) ◽  
pp. 289-295 ◽  
Author(s):  
J. L. Stein ◽  
Kyung-Chul Shin
Keyword(s):  
Signal To Noise Ratio ◽  
Operating Conditions ◽  
Lumped Parameter Model ◽  
Cnc Machine ◽  
Spindle System ◽  
High Speeds ◽  
Lumped Parameter ◽  
Cnc Lathe ◽  
Speed Range ◽  
Current Monitoring

Unmanned machine tools as part of an automated factory require reliable inexpensive sensors to provide machine and process information. The electric current in the DC motor of a CNC machine tool can be inexpensively measured and used to calculate loads on the drive system. To characterize the bandwidth, sensitivity and accuracy of current monitoring on a DC field controlled spindle drive of a CNC lathe, a dynamic lumped parameter model of this sensor system is developed. The model is used to identify the system components that have a dominant effect on the behavior of the sensor when the spindle system is operated above the base speed. Tests were conducted to determine the model’s parameters and to verify the model. The bandwidth and sensitivity of this sensor are shown to be spindle speed dependent. High speeds improve sensitivity and reduce bandwidth. Sensitivity and bandwidth vary by factors of 4.3 and 18.5, respectively, over the speed range. The signal to noise ratio is limited by external load induced variations in the spindle system friction. Recommendations concerning machine designs and process operating conditions to improve current monitoring on spindle drives are presented.

Interaction Between Coriolis Forces and Mistuning on a Cyclic Symmetric Structure With Geometrical Nonlinearity

2020 ◽  
Author(s):  
Anthony Tacher ◽  
Fabrice Thouverez ◽  
Jason Armand
Keyword(s):  
Standing Wave ◽  
Geometrical Nonlinearity ◽  
Numerical Approach ◽  
Travelling Wave ◽  
Lumped Parameter Model ◽  
Coriolis Forces ◽  
High Speeds ◽  
Symmetric Structure ◽  
Lumped Parameter ◽  
Cyclic Symmetric

Abstract An investigation of the interaction between Coriolis forces and mistuning on a cyclic symmetric structure is presented in this paper. The sensitivity of the eigenvalues and eigenvectors to mistuning is first studied with the perturbation method. A lumped parameter model is used to perform a modal analysis using a numerical approach after which geometrical nonlinearity is added to compare behavior with the linear case. Two different modes are thoroughly investigated for different rotational speeds, the first with an eigenvalue isolated from the others and the second presenting a frequency veering zone. The evolution from a standing wave domination at low speeds to a travelling wave domination at high speeds is observed for the isolated mode, whereas a standing wave domination remains around the veering zone for the second mode studied. It is also shown that the geometrical nonlinearity reinforces the mistuning effect versus the Coriolis forces.

Interaction Between Coriolis Forces and Mistuning on a Cyclic Symmetric Structure with Geometrical Nonlinearity

2020 ◽  
Author(s):  
Anthony Tacher ◽  
Fabrice Thouverez ◽  
Jason Armand
Keyword(s):  
Standing Wave ◽  
Geometrical Nonlinearity ◽  
Numerical Approach ◽  
Travelling Wave ◽  
Lumped Parameter Model ◽  
Coriolis Forces ◽  
High Speeds ◽  
Symmetric Structure ◽  
Lumped Parameter ◽  
Cyclic Symmetric

Abstract An investigation of the interaction between Coriolis forces and mistuning on a cyclic symmetric structure is presented in this paper. The sensitivity of the eigenvalues and eigenvectors to mistuning is first studied with the perturbation method. A lumped parameter model is used to perform a modal analysis using a numerical approach after which geometrical nonlinearity is added to compare behavior with the linear case. Two different modes are thoroughly investigated for different rotational speeds, the first with an eigenvalue isolated from the others and the second presenting a frequency veering zone. The evolution from a standing wave domination at low speeds to a travelling wave domination at high speeds is observed for the isolated mode, whereas a standing wave domination remains around the veering zone for the second mode studied. It is also shown that the geometrical nonlinearity reinforces the mistuning effect versus the Coriolis forces.

Planetary Gear Modal Properties and Dynamic Response: Experiments and Analytical Simulation

2011 ◽  
Author(s):  
Tristan M. Ericson ◽  
Robert G. Parker
Keyword(s):  
Natural Frequencies ◽  
Planetary Gear ◽  
Forced Response ◽  
Operating Conditions ◽  
Modal Testing ◽  
Lumped Parameter Model ◽  
Lumped Parameter ◽  
Analytical Simulation ◽  
Analytical Research ◽  
Independent Motion

Planetary gear vibration is a major source of noise and may lead to fatigue-induced failures in bearings or other drivetrain components. Gear designers use mathematical models to analyze potential designs, but these models remain unverified by experimental data. This paper presents experiments that completely characterize the dynamic behavior of a spur planetary gear by modal testing and spinning tests under representative operating conditions, focusing on the independent motion of planetary components. Accelerometers are mounted directly to individual gear bodies. Rotational and translational accelerations obtained from the experiments are compared to the predictions of a lumped parameter model. Natural frequencies, modes, and forced response agree well between experiments and the model. Rotational, translational, and planet mode types presented in published analytical research are observed experimentally.

Lumped parameter modelling for the thermal analysis of the launch vehicle Vega C

2018 ◽  
Vol 90 (3) ◽  
pp. 542-558
Author(s):  
Mattia Olivero ◽  
Matteo Ferrai ◽  
Piero Pantaleone ◽  
Ivan Perkovic ◽  
Antonella D’Amato ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Thermal Protection ◽  
Time Frame ◽  
Launch Vehicle ◽  
Operating Conditions ◽  
Lumped Parameter Model ◽  
Content Type ◽  
Flight Phase ◽  
Second Stage ◽  
Lumped Parameter

Purpose This activity dealt with the thermal analysis of the launch vehicle Vega C through a lumped parameter model. The Vega C is the upgrade of the actual launch vehicle Vega within the Vega Consolidation and Evolution Program, whose objective is to develop a consolidated – hence the C – version of the Vega by 2020. The main aim of the study was verifying the thickness of the external thermal protection of the launch vehicle, such that the structure and equipment temperatures were kept within their operating ranges. Design/methodology/approach The analysis has been performed by means of ESATAN–TMS during a time-frame that included the stand-by on ground phase and a flight phase up to the separation of the second stage from the third one. Two operating conditions have been considered, i.e. the worst hot and worst cold cases. The study has been divided as follows: geometry definition through spatial discretization; application of materials and optical properties; application of thermal loads; thermal analysis; and post-processing of the results in ThermNV. Findings It was concluded that the calculated temperatures were within the supposed project specifications, while their trends reflected the expected behavior. Originality/value During the flight phase, the mutual separation of the investigated stages has been explicitly modelled through a routine specifically developed for this purpose. Therefore, the submodels of each stage have been disabled at the correct instant according to the known time-sheet.

A Critical Examination of the Hysteresis in Wells Turbines Using Computational Fluid Dynamics and Lumped Parameter Models

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Tiziano Ghisu ◽  
Francesco Cambuli ◽  
Pierpaolo Puddu ◽  
Irene Virdis ◽  
Mario Carta ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbine Blades ◽  
Unsteady Aerodynamics ◽  
Operating Conditions ◽  
Lumped Parameter Model ◽  
Hysteretic Behavior ◽  
Critical Examination ◽  
Wells Turbine ◽  
Lumped Parameter

Abstract The hysteretic behavior of oscillating water column (OWC)-installed Wells turbines has been known for decades. The common explanation invokes the presence of unsteady aerodynamics due to the continuously varying incidence of the flow on the turbine blades. This phenomenon is neither new nor unique to Wells turbines, as an aerodynamic hysteresis is present in rapidly oscillating airfoils and wings, as well as in different types of turbomachinery, such as wind turbines and helicopter rotors, which share significant similarities with a Wells turbine. An important difference is the non-dimensional frequency: the hysteresis appears in oscillating airfoils only at frequencies orders of magnitude larger than the ones Wells turbines operate at. This work contains a re-examination of the phenomenon, using both computational fluid dynamics (CFD) and a lumped parameter model, and shows how the aerodynamic hysteresis in Wells turbines is negligible and how the often measured differences in performance between acceleration and deceleration are caused by the capacitive behavior of the OWC system. Results have been verified with respect to both spatial and temporal discretization, for unstalled and stalled operating conditions.

Quasi-static and dynamic analyses of thin-webbed high-speed gears: Centrifugal effect influence

2019 ◽  
Vol 233 (21-22) ◽  
pp. 7282-7291
Author(s):  
B Guilbert ◽  
P Velex ◽  
P Cutuli
Keyword(s):  
Finite Elements ◽  
High Speed ◽  
Operating Conditions ◽  
Centrifugal Effect ◽  
High Speeds ◽  
Load Distributions ◽  
Lumped Parameter ◽  
Dynamic Analyses ◽  
Gear Geometry

The objective of this paper is to analyse the effect of centrifugal effects on thin-rimmed/-webbed gears. To this end, an original hybrid gear model is used, which combines lumped parameter elements, finite elements and condensed sub-structures along with a mortar-based mesh interface aiming at coupling mismatched models. It is shown that due to gear body flexibility, centrifugal effects can strongly modify geometry and, consequently, tooth load distributions at high speeds. The possibility to counterbalance these effects by introducing profile and lead modification is investigated. It is finally shown that for the effective tooth design, both thin-rimmed gear geometry and operating conditions must be accounted for.

On Testing and Modeling Automotive Spool-Type Hydraulic Valve With Circular Flow Ports

2004 ◽  
Author(s):  
M. Cao ◽  
K. W. Wang ◽  
L. DeVries ◽  
Y. Fujii ◽  
W. E. Tobler ◽  
...  
Keyword(s):  
Flow Rate ◽  
Discharge Coefficient ◽  
Operating Conditions ◽  
Lumped Parameter Model ◽  
New Approach ◽  
Fluid Force ◽  
Valve System ◽  
Fluid Field ◽  
Lumped Parameter ◽  
Hydraulic Valve

This paper describes empirical investigations of the fluid field for a spool-type hydraulic valve with symmetrically distributed circular ports that is often found in an automotive VFS (Variable Force Solenoid) valve system. Through extensive data analysis, a general trend of fluid force and flow rate is derived as a function of pressure drop and valve opening. Aiming at further revealing the insights of the steady state spool valve fluid field, the equivalent jet angle and discharge coefficient are calculated from the measurements based on the lumped parameter models. New Non-Dimensional Artificial Neural Network (NDANN)-based hydraulic valve system models are also developed in this paper through the use of equivalent jet angle and discharge coefficient. By introducing the outputs of the new NDANN models into the lumped parameter model, fluid force and flow rate can be easily calculated. Therefore, the new approach calculates fluid force and flow rate as well as the intermediate variables (equivalent jet angle and discharge coefficient) with useful design implications. The network training and testing demonstrate that the NDANN fluid field estimators can accurately capture the relationship between the key geometry parameters and discharge coefficient/jet angle. The new approach also maintains the non-dimensional network configuration and possesses scalability with respect to the geometry parameters and key operating conditions. All these features make the new NDANN fluid field estimator a valuable tool for automotive hydraulic system design.

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