Dynamic Acceptance Test for Machine Tools Based on a Nonlinear Stochastic Model

1980 ◽  
Vol 102 (1) ◽  
pp. 58-63 ◽  
Author(s):  
M. Samaha ◽  
T. S. Sankar
Keyword(s):  
Machine Tool ◽  
Metal Cutting ◽  
Dynamic Stiffness ◽  
Wide Band ◽  
Linearization Method ◽  
Statistical Linearization ◽  
Acceptance Test ◽  
Band Form ◽  
Degree Of Acceptance ◽  
Two Degree Of Freedom

A nonlinear two-degree-of-freedom mathematical model of a general machine tool is considered for describing the responses in translational and rotational modes under the action of the actual randomly fluctuating metal cutting forces in a Gaussian, wide band form. The response process is determined by the Fokker-Planck technique for the simplified case and also by the statistical linearization method for the general case to establish accuracy of the results obtained. Based on the variances of the response derived and the system constants, a dynamic stiffness coefficient Kd is proposed for defining the degree of acceptance of a given machine tool under actual cutting conditions. Numerical results for specific examples are provided for purpose of illustration.

Active Control of Machine Tool Chatter for a Boring Bar: Experimental Results

1993 ◽  
Author(s):  
Sanjiv G. Tewani ◽  
Thad C. Switzer ◽  
Bruce L. Walcott ◽  
Keith E. Rouch ◽  
Ted R. Massa
Keyword(s):  
Machine Tool ◽  
Metal Cutting ◽  
Dynamic Stiffness ◽  
Dynamic Equations ◽  
Control Machine Tool ◽  
Boring Bar ◽  
State Variable ◽  
Machine Tool Chatter ◽  
Dynamic Absorber ◽  
Tool Chatter

Abstract A typical boring bar is a metal cutting tool with large overhang ratio, due to which it is characterized by low dynamic stiffness. Therefore, during cutting process, it is susceptible to cutting instability, known as machine tool chatter. In this paper, the use of an active dynamic absorber to actively control machine tool chatter in a boring bar is studied. An active dynamic absorber is designed such that it can be easily assembled with a commercially available steel boring bar. A piezoelectric pusher is used as the actuator for the active dynamic absorber. The dynamic equations of the boring bar with active dynamic absorber are calculated from experimentally obtained frequency response functions of the system. Optimal control theory is applied to the dynamic equations to calculate state variable feedback parameters. The state variable feedback is implemented using a Digital Signal Processing (DSP) chip. Cutting tests were performed with this setup for different cutting conditions, and for different overhangs of the boring bar. Stable cutting operations were performed using the boring bar with active dynamic absorber, for length to diameter (L/D) ratio upto 9.

Short-Time Acceptance Test for Machine Tools Based on the Random Nature of the Cutting Forces

1972 ◽  
Vol 94 (4) ◽  
pp. 1020-1024 ◽  
Author(s):  
M. O. M. Osman ◽  
T. S. Sankar
Keyword(s):  
Machine Tool ◽  
Cutting Forces ◽  
Machine Tools ◽  
Dynamic Stiffness ◽  
Planck Equation ◽  
Random Fluctuation ◽  
Acceptance Test ◽  
Noise Spectral Density ◽  
Time Dynamic ◽  
Short Time

A short-time dynamic acceptance test for machine tools based on a single measurement of a coefficient of dynamic stiffness (Kd) is proposed. A feature of this test is that it takes into account the random fluctuation of the cutting forces that will be experienced by the machine tool in actual operation. Kd is defined as the inverse of the standard deviation of the steady state translational dynamic response of the machine tool under these cutting forces and is a function of the static stiffness of the machine-tool-workpiece system, the damping in the machine, and the equivalent intensity coefficient of the random cutting forces. The analytical expression for the coefficient Kd is obtained from the stationary solution of the Fokker-Planck equation that describes the probabilistic response of the machine tool. The form of excitation considered in the final results is the equivalent “white-noise” spectral density of the ensemble of the cutting forces experienced by the particular machine over the range of feed rates and cutting speeds during operations such as roughing, finishing, etc.

Metal Cutting Machine Tool Design—A Review

1997 ◽  
Vol 119 (4B) ◽  
pp. 713-716 ◽  
Author(s):  
S. B. Rao
Keyword(s):  
Machine Tool ◽  
Metal Cutting ◽  
Tool Design ◽  
Metal Cutting Machine ◽  
Machine Tool Design ◽  
Cutting Machine

This paper reviews the key developments in the area of metal cutting machine tool design over the last three decades, from a very practical perspective. While defining the drivers of machine tool design as higher productivity and higher accuracy, this paper examines the advances in design from the needs of these two drivers.

Dynamic Analysis of Helical Milling Unit Based on Virtual Machine Tool

2011 ◽  
Vol 188 ◽  
pp. 463-468 ◽  
Author(s):  
Xu Da Qin ◽  
Qi Wang ◽  
H.Y. Wang ◽  
Song Hua
Keyword(s):  
Machine Tool ◽  
Virtual Machine ◽  
Dynamic Stiffness ◽  
Three Dimensional ◽  
Geometrical Model ◽  
Helical Milling ◽  
Response Analysis ◽  
Computer Simulation Model ◽  
Element Analysis ◽  
Virtual Machine Tool

The virtual prototype is a computer simulation model of the physical product that can be analyzed like a real machine. This paper studies the helical milling unit based on the virtual machine tool. The helical milling unit is first designed according to the kinematics of the helical milling. The main parts of the equipment include rotating mechanism, orbital agency and radial offset organization. Based on the feasibility analysis of the structure, the three-dimensional geometrical model is built in the Solidworks software. The key parts in the model are separated from the device and introduced into the finite element analysis (FEA) software, according to the cutting loads tested from experiment, static and dynamic modal analysis and harmonic response analysis are carried out for the key parts of this device. The results show that the static and dynamic stiffness can meet design requirement.

Model Research on Special Metal Cutting NC Machine Tool

2007 ◽  
Vol 10-12 ◽  
pp. 806-811
Author(s):  
Tong Zhao ◽  
P.Q. Ye ◽  
H. Zhang ◽  
X.K. Wang
Keyword(s):  
Machine Tool ◽  
Metal Cutting ◽  
Relation Module ◽  
Nc Machine Tool ◽  
Model Research ◽  
Unit Model ◽  
Proposed Model ◽  
Control Research ◽  
Function Unit ◽  
Nc Machine

In this paper the model of special metal cutting NC machine Tool is presented, which consists of a base module, an overall control module, particular functional modules as well as a relation module. Each module involved in aforementioned model will be composed by software, hardware and mechanical parts, so as to combine the convergence of the ideas of modularization and mechanical-electrical integration into current understanding of special NC machine tool through the proposed model. Specially, the relation module is introduced to deal with the linking among all the other modules. The presented model aims to broaden the perspective of machine designers intending to increase the efficiency in machine design. By giving the so-called function unit model a novel modeling approach is delivered to carry out control research of special metal cutting NC machine, which is followed by the formalization description method presented as a possible abstraction methodology towards the efficient description and identification of special metal cutting NC machine tool.

H∞Control for PMLSM Suspension Platform Based on PDFF

2011 ◽  
Vol 383-390 ◽  
pp. 6886-6892
Author(s):  
Jia Kuan Xia ◽  
Yi Na Wang ◽  
Yi Biao Sun
Keyword(s):  
Feedback Linearization ◽  
High Speed ◽  
Normal Force ◽  
Dynamic Stiffness ◽  
Linearization Method ◽  
Dynamic Decoupling ◽  
Fast Tracking ◽  
Speed Controller ◽  
Simulation Results ◽  
Proportional Controller

Permanent magnet linear synchronous motor (PMLSM) suspension system has the merits of no friction, high-speed, high response and so on, using the normal force achieve the mover suspension. The servo performance is affected by the nonlinear coupling between the horizontal trust and vertical normal force, parameters uncertainties and load disturbances. The feedback linearization method is used to achieve the dynamic decoupling of the PMLSM suspicion system and decoupling it Into two linear subsystems; to solve the conflict between disturbance restraint and fast tracking performance, increase the robustness and dynamic stiffness for system, H∞ speed controller based on PDFF and position proportional controller are designed. Simulation results show that the proposed control strategy guarantees the high speed and high precision positioning performance for horizontal axis; the good rigidity and stability for normal suspension length and the strong robustness against load disturbances and parameters variations for the two axes.

Research on Kinematic Analysis and Post Processing Arithmetic for NC Machine Tool for Bonnet Tool Polishing

2007 ◽  
Vol 364-366 ◽  
pp. 707-712
Author(s):  
Ying Xue Yao ◽  
Shun Zhou Yu ◽  
Da Gang Xie
Keyword(s):  
Machine Tool ◽  
Metal Cutting ◽  
Transformation Method ◽  
Programming System ◽  
Automatic Programming ◽  
Post Processing ◽  
Nc Machine Tool ◽  
Nc Programming ◽  
Nc Machine ◽  
Optical Polishing

Bonnet tool polishing, combined traditional optical polishing technique with modern NC technology, is an novel optical polishing technique. As the motion control and material removal process is different from metal cutting NC machine tool, the NC programming for bonnet tool polishing NC machine tools cannot be carried out with commercial CAM software. This paper analyses the kinematics of feed mechanism and precession mechanism using coordinate transformation method and sets up the feed and precession kinematics equations. The arithmetic of post processing applied to NC automatic programming system is proposed according to kinematics equations and detail bonnet tool polishing technique.

Practices of modernization of metal-cutting machine tool CNC systems

2021 ◽  
pp. 247-255
Author(s):  
V. Sychuk ◽  
O. Zabolotnyi ◽  
P. Harchuk ◽  
D. Somov ◽  
A. Slabkyi ◽  
...  
Keyword(s):  
Machine Tool ◽  
Metal Cutting ◽  
Metal Cutting Machine ◽  
Cutting Machine

Modeling and Simulation of Process and Structure Interactions Considering Turning Operations

2009 ◽  
Author(s):  
Michael F. Zaeh ◽  
Florian Schwarz
Keyword(s):  
Machine Tool ◽  
Cutting Force ◽  
Metal Cutting ◽  
Material Behavior ◽  
Force Model ◽  
Machine Tool Structure ◽  
Simulation Based ◽  
Turning Center ◽  
Simplifying Assumptions ◽  
Input Variables

A consideration of the dynamic interaction between the machine tool structure and the cutting process is required for the prediction and optimization of machining tasks through simulation. This paper outlines a modular, analytical cutting force model applicable to common turning processes. It takes into account the dynamic material behavior and nonlinear friction ratios on the rake face as well as heat transfer phenomena in the deformation zones. In order to overcome simplifying assumptions in analytical cutting force descriptions and to incorporate the chip formation process into the analysis, specific input variables are determined in a metal cutting simulation based on the Finite Element Method (FEM). On the machine tool structure side, the setup of a parametric FEM model is presented. The accuracy of both the machine tool and cutting force models was verified experimentally on a turning center.

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