Machine Tool Axis Dynamics

2006 ◽  
Vol 220 (4) ◽  
pp. 403-419 ◽  
Author(s):  
R Whalley ◽  
M Ebrahimi ◽  
A A Abdul-Ameer
Keyword(s):  
Machine Tool ◽  
System Analysis ◽  
Block Diagram ◽  
Workpiece Surface ◽  
Lumped Parameter ◽  
Tool Axis ◽  
Screw Length ◽  
Axis Drive ◽  
Dynamic Signature ◽  
Tension Loading

The independent axis dynamics of machine tools that employ long slender lead screws, bearings, and workpiece saddles, mounted on supporting slides, will be considered. Distributed-lumped parameter techniques will be used for system analysis and in the model formulation procedures. Realizations that encompass combined torsional and tension loading will be incorporated. Specific, integrated, distributed-lumped machine tool configurations will be derived and described in block diagram form. Simulation studies illustrating the dynamic signature of a machine tool axis drive, when operated at various feed rates, together with the measured results will be presented. The effect of changes in the effective lead-screw length on the workpiece surface finish will be commented on.

Determination of stiffness and damping sensitivity for computer numerically controlled machine tool drives

2003 ◽  
Vol 217 (10) ◽  
pp. 1165-1177 ◽  
Author(s):  
G Holroyd ◽  
C Pislaru ◽  
D G Ford
Keyword(s):  
Machine Tool ◽  
Mode Shapes ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Damping Characteristics ◽  
Tool Axis ◽  
Computer Numerically Controlled ◽  
Axis Drive ◽  
Machine Drives ◽  
Stiffness And Damping

A generalized eigenvalue method is used to determine the undamped and damped natural frequencies, coefficients of damping and mode shapes of a computer numerically controlled (CNC) machine tool drive. The calculated results compare well with the measured results obtained by using vibration analysis equipment. Then the sensitivity of the various modes to changes in the stiffness and damping characteristics of the machine drives is estimated. These values prove to be useful in adjusting the parameters of a hybrid model for a CNC machine tool axis drive in order to alter the simulated results in accordance with the measured results.

A New Model Towards Thermal Mixing and Stratification in Passive Containment

2013 ◽  
Author(s):  
He Zhang ◽  
Fenglei Niu ◽  
Yu Yu ◽  
Peipei Chen
Keyword(s):  
Heat Transfer ◽  
System Analysis ◽  
Cooling System ◽  
Transfer Problem ◽  
Ambient Fluid ◽  
Simulation Code ◽  
Thermal Mixing ◽  
Lumped Parameter ◽  
Passive Safety System ◽  
Transfer Problems

Thermal mixing and stratification often appears in passive containment cooling system (PCCS), which is an important part of passive safety system. So, it is important to accurately predict the temperature and density distributions both for design optimization and accident analysis. However, current major reactor system analysis codes only provide lumped parameter models which can only get very approximate results. The traditional 2-D or 3-D CFD methods require very long simulation time, and it’s not easy to get result. This paper adopts a new simulation code, which can be used to calculate heat transfer problems in large enclosures. The new code simulates the ambient fluid and jets with different models. For the ambient fluid, it uses a one-dimensional model, which is based on the thermal stratification and derived from three conservation equations. While for different jets, the new code contains several jet models to fully simulate the different break types in containment. Now, the new code can only simulate rectangular enclosures, not the cylinder enclosure. So it is meaningful for us to modify the code to simulate the actual containment, then it can be applied to solve the heat transfer problem in PCCS accurately.

New Development in High Efficiency Deep Grinding

2012 ◽  
Author(s):  
Andre D. L. Batako ◽  
Valery V. Kuzin ◽  
Brian Rowe
Keyword(s):  
Machine Tool ◽  
High Efficiency ◽  
Machining Process ◽  
Depth Of Cut ◽  
Removal Rates ◽  
Workpiece Surface ◽  
New Development ◽  
Cutting Processes ◽  
Selection Of ◽  
Made In

High Efficiency Deep Grinding (HEDG) has been known to secure high removal rates in grinding processes at high wheel speed, relatively large depth of cut and moderately high work speed. High removal rates in HEDG are associated with very efficient grinding and secure very low specific energy comparable to conventional cutting processes. Though there exist HEDG-enabled machine tools, the wide spread of HEDG has been very limited due to the requirement for the machine tool and process design to ensure workpiece surface integrity. HEDG is an aggressive machining process that requires an adequate selection of grinding parameters in order to be successful within a given machine tool and workpiece configuration. This paper presents progress made in the development of a specialised HEDG machine. Results of HEDG processes obtained from the designed machine tool are presented to illustrate achievable high specific removal rates. Specific grinding energies are shown alongside with measured contact arc temperatures. An enhanced single-pole thermocouple technique was used to measure the actual contact temperatures in deep cutting. The performance of conventional wheels is depicted together with the performance of a CBN wheel obtained from actual industrial tests.

A Lumped Parameter Electromechanical Model for Describing the Nonlinear Behavior of Piezoelectric Actuators

1997 ◽  
Vol 119 (3) ◽  
pp. 478-485 ◽  
Author(s):  
M. Goldfarb ◽  
N. Celanovic
Keyword(s):  
System Analysis ◽  
Nonlinear Behavior ◽  
Piezoelectric Actuators ◽  
Bond Graph ◽  
Lumped Parameter Model ◽  
Input Output ◽  
Mechanical Stiffness ◽  
Analysis And Design ◽  
Lumped Parameter ◽  
Proposed Model

A lumped-parameter model of a piezoelectric stack actuator has been developed to describe actuator behavior for purposes of control system analysis and design, and in particular for control applications requiring accurate position tracking performance. In addition to describing the input-output dynamic behavior, the proposed model explains aspects of nonintuitive behavioral phenomena evinced by piezoelectric actuators, such as the input-output rate-independent hysteresis and the change in mechanical stiffness that results from altering electrical load. Bond graph terminology is incorporated to facilitate the energy-based formulation of the actuator model. The authors propose a new bond graph element, the generalized Maxwell resistive capacitor, as a lumped-parameter causal representation of rate-independent hysteresis. Model formulation is validated by comparing results of numerical simulations to experimental data.

scholarly journals Building lifecycle management based on 4D modelling as the main workspace for building risk assessment

2020 ◽  
Vol 224 ◽  
pp. 02023
Author(s):  
R Kazaryan ◽  
N Galaeva ◽  
R Avetisyan ◽  
Sh Aliev
Keyword(s):  
Information Technology ◽  
Life Cycle ◽  
System Analysis ◽  
Planning Process ◽  
Block Diagram ◽  
Labour Productivity ◽  
Development Trend ◽  
Basic Block ◽  
Mathematical Methods ◽  
Element Base

The use of information technology in the management of construction projects has become a decisive factor for the successful completion of projects, taking into account time, quality and financial costs. There are challenges in visualizing the planning process and integrating information between stakeholders. The paper considers some aspects of the development trend of information technology in construction. The element base, including the risks arising during the design and construction, associated with the direct use of computer and mathematical models of the object in the design is considered. The generated information models will provide basic information for the participants in the design process, which ultimately will be the basis of the element base of an effective tool for ensuring project life cycle management. The following methods were used: system analysis, logical-mathematical modelling, systems theory, economic-visual modelling, research methods of operations, economic and mathematical methods. A basic block diagram of 4D modelling is presented to minimize the occurrence of risks during design. The model allows considering the possibility of assessing the duration of the project, the level of labour productivity, as well as visualizing the construction process. The presented analysis indicates the importance of using 4D modelling in relation to the life cycle of the object in order to prevent the possibility of construction risks.

scholarly journals Sensitivity Analysis of the Transmission Chain of a Horizontal Machining Tool Axis to Design and Control Parameters

2014 ◽  
Vol 6 ◽  
pp. 169064 ◽  
Author(s):  
Stefano Mauro ◽  
Stefano Pastorelli ◽  
Tharek Mohtar
Keyword(s):  
Sensitivity Analysis ◽  
Lumped Parameter Model ◽  
Control Parameters ◽  
Damping Coefficients ◽  
Transmission Chain ◽  
Lumped Parameter ◽  
Tool Axis ◽  
Optimal Value ◽  
Structural Parts ◽  
And Control

This paper reports how a numerical controlled machine axis was studied through a lumped parameter model. Firstly, a linear model was derived in order to apply a modal analysis, which estimated the first mechanical frequency of the system as well as its damping coefficients. Subsequently, a nonlinear system was developed by adding friction through experimentation. Results were validated through the comparison with a commercial servoaxis equipped with a Siemens controller. The model was then used to evaluate the effect of the stiffness of the structural parts of the axis on its first natural frequency. It was further used to analyse precision, energy consumption, and axis promptness. Finally a cost function was generated in order to find an optimal value for the main proportional gain of the position loop.

Study on Tool Path Algorithm for Mushroom Blade Boot in 4_Axis Machining

2010 ◽  
Vol 156-157 ◽  
pp. 1238-1242
Author(s):  
Kui Zhou ◽  
Si Tu Yu ◽  
Shi De Xiao
Keyword(s):  
Machine Tool ◽  
Turbine Blade ◽  
Tool Path ◽  
Variable Parameter ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Tool Axis ◽  
Motion Characteristics ◽  
Cutting Point

According to the motion characteristics of 4-axis CNC machine tool, this paper studies a new way for manufacturing the mushroom turbine blade boot .It must rotate the turbine blade to ensure the tool axis consistent with the normal of the interpolating point on the arc of the blade boot, and move the tool to keep the cutting point in contact with the interpolating point. Meanwhile, this paper researches an algorithm to calculate the tool path in the MCS, According to this algorithm, a program with R variable parameter for manufacturing the mushroom turbine blade boot is provided.

Modal Analysis of High-Speed Face Milling System Based on Composite Structure System Analysis Method

2014 ◽  
Vol 800-801 ◽  
pp. 408-413
Author(s):  
Lu Ning Liu ◽  
Zhen Yu Shi ◽  
Zhan Qiang Liu ◽  
Hao Song
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Composite Structure ◽  
High Speed ◽  
System Analysis ◽  
Face Milling ◽  
Analysis Method ◽  
Milling Cutter ◽  
Structure System ◽  
The Face

This paper adopts composite structure system analysis method to perform modal analysis of high-speed face milling cutter which is mounted on the machine tool through FEM modal analysis. The key problem of this method is to obtain joint surface parameters between the machine tool spindle and face milling cutter through experimental modal analysis and MATLAB software. The joint surface parameters consist of linear stiffness, linear damping, rotation stiffness and rotation damping. After getting the frequency response function (FRF) at the tool tip of the face milling system through experimental modal analysis, the contact surface parameters can be used to eliminate the influence of the machine tool to get modal parameters of the face-milling cutter itself. Based on the finite element model of face milling cutter, composite structure system analysis method can be used easily to acquire the dynamic performance of the face milling system through FEM modal analysis, greatly to improve the reliability of modal analysis, and is helpful to the dynamic design and the structure improvement of high speed face milling cutter.

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