Study on Method to Avoid Chatter Vibration Based on Machine Tool Rigidity

2020 ◽  
Author(s):  
Akio Hayashi ◽  
Hiroto Ishibashi ◽  
Yoshitaka Morimoto ◽  
Yoshiyuki Kaneko ◽  
Naohiko Suzuki
Keyword(s):  
Machine Tool ◽  
Frequency Response ◽  
Frequency Response Function ◽  
Stability Limit ◽  
Cutting Conditions ◽  
Machining Accuracy ◽  
Stable Limit ◽  
Chatter Vibration ◽  
The Stability ◽  
The Relationship

Abstract Chatter vibration decreases machining accuracy and thus presents a problem in manufacturing. In order to eliminate chatter vibration based on the estimation of stable cutting conditions from a stability limit diagram and to determine the cutting conditions accordingly has been proposed. However, changing the cutting conditions may lead to a decrease in productivity. The stability limit is estimated from the relationship between machine rigidity and the cutting conditions. In the present study, we proposed a system to avoid chatter vibration by changing the rigidity of the machine tool. We developed the desktop machine tool that can change its rigidity by varying the preload of a brace bar attached to the frame. In order to clarify the relationship between the chatter vibration and the rigidity of the desktop machine tool, the stability limit of the desktop machine tool was determined by conducting machining tests and comparing the results with a simulated stable limit diagram. We then investigated the frequency response function within the simulation. The results showed that the transition of the stability limit can be accomplished by changing the rigidity of the desktop machine tool, and indicate that chatter vibration can be avoided by simulation.

Determination of Machine Tool Frequency Response Function During Cutting

2004 ◽  
Author(s):  
Emmanuil Kushnir
Keyword(s):  
Steady State ◽  
Machine Tool ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Dynamic Compliance ◽  
Cutting Conditions ◽  
Machine Tool Structure ◽  
Different Types ◽  
External Sources

The dynamic compliance (frequency response function - FRF) of a machine tool structure in the cutting zone under a cutting load is one of the major dynamic characteristics that define a machine’s cutting performance. The roundness and surface finish define the quality of the manufactured parts. These characteristics are developed during finishing and semi-finishing cuts. The kinowledge of machine tool dynamic compliance, defined in these steady-state cutting conditions, ensures parts quality and increase in machine tool productivity. The dynamic compliance is usually evaluated in tests, which are performed by means of hammers or vibrators (exciters). During these tests the machine does not cut and the machine components do not move relative to each other. The loads in the machine during cutting are defined by different internal and external sources that are acting in different points of the machine and in different directions. The real spectrum and frequency range of these forces is unknown. Experimental data acquired by different types of tests clearly show the difference in dynamic compliance for the same machine tool during cutting and idling. The machine tool dynamic tests performed by different types of external exciting devices do not take in consideration the real load conditions and interactions of moving components, including the cutting process itself and external sources of vibration. The existing methods of experimental evaluation of machine tool dynamic compliance during steady-state cutting condition require dynamometers to measure the cutting force and a special sensor to measure relative displacement between the cutting tool and workpiece. The FRF that is computed from these measurements represents a dynamic characteristic of the close loop system (machine structure and cutting process) and only under certain conditions may be considered as FRF of machine tool structure itself. The theory of stationary random processes allows defining the cutting conditions, under which the obtained data represent the FRF of machine tool structure, and provide estimations of random and bias errors of this evaluation. The simplified methodology of FRF estimation, based only on measurement of the spindle and tool vibration, is also presented in this paper. This methodology is used on an assembly line to obtain FRF for machine tools performance comparison and quality assurance.

Stability Prediction in Turning of Flexible Components

2010 ◽  
Vol 112 ◽  
pp. 149-157 ◽  
Author(s):  
Gorka Urbicain ◽  
David Olvera ◽  
Luis Norberto López de Lacalle ◽  
Francisco Javier Campa
Keyword(s):  
Machine Tool ◽  
Surface Quality ◽  
Classical Problem ◽  
Cutting Conditions ◽  
Stability Prediction ◽  
Nose Radius ◽  
The Stability ◽  
Tool Nose Radius ◽  
Flexible Components

Chatter is the most classical problem in machining. It is prone to occur in low rigidity structures generating poor surface quality and harmful vibrations which could damage any part of the machine-tool system. In finishing operations, the effect of the tool nose radius should be taken into account in order to obtain safe and reliable cutting conditions. The present paper uses a simple SDOF model to study the stability during finishing operations.

An Accuracy-Prediction Model Taking Tool Deformation and Geometric Machine-Tool Error into Consideration

2010 ◽  
Vol 4 (3) ◽  
pp. 235-242 ◽  
Author(s):  
Hirohisa Narita ◽  
◽  
Keiichi Shirase ◽  
Eiji Arai ◽  
Hideo Fujimoto ◽  
...  
Keyword(s):  
Prediction Model ◽  
Machine Tool ◽  
End Milling ◽  
Geometric Error ◽  
Cutting Conditions ◽  
Error Prediction ◽  
Machining Accuracy ◽  
Trial And Error ◽  
Virtual Machining ◽  
Nc Program

Test cutting used to verify cutting conditions and machining accuracy after a numeric control (NC) program is written for end milling the mold and die indispensable to manufacturing is generally effective, because it is based on trial and error. The virtual machining simulator we designed to verify machining accuracy uses an accuracy-prediction model and an error prediction expression for workpieces, integrating machine-tool deformation and geometric error models. We also propose calculation for copying errors to a workpiece.

Dynamic Stability of a Motorized High Speed Machine Tool Spindle Supported on Bearings

2014 ◽  
Vol 612 ◽  
pp. 29-34
Author(s):  
Jakeer Hussain Shaik ◽  
J. Srinivas
Keyword(s):  
Machine Tool ◽  
Frequency Response ◽  
High Speed ◽  
Stability Boundary ◽  
Second Phase ◽  
Element Formulation ◽  
Machining Parameters ◽  
Response Functions ◽  
Frequency Response Functions ◽  
The Stability

Dynamic behaviour of spindle system influences chatter stability of machine tool considerably. Self-excited vibrations of the tool results in unstable cutting process which leads to the chatter on the work surface and it reduces the productivity. In this paper, a system of coupled spindle bearing system is employed by considering the angular contact ball bearing forces on stability of machining. Using Timoshenko beam element formulation, the spindle unit is analyzed by including the gyroscopic and centrifugal terms. Frequency response functions at the tool-tip are obtained from the dynamic spindle model. In the second phase, solid model of the system is developed and its dynamic response is obtained from three dimensional finite element analysis. The works on analysis of the stability of milling processes focus on calculating the stability boundary of the machining parameters based on the dynamic models characterizing the milling processes. The stability lobe diagrams are generated from frequency response functions (FRF’s) lead to an stability limit prediction for the system at high speed ranges.

scholarly journals Decomposition of milling operation

2018 ◽  
Vol 224 ◽  
pp. 01136
Author(s):  
Yurij Novoselov ◽  
Mariya Piankovskaya ◽  
Vladimir Bogutsky
Keyword(s):  
Machine Tool ◽  
Contact Zone ◽  
Block Diagram ◽  
Quality Parameters ◽  
Machining Process ◽  
Milling Operation ◽  
The Stability ◽  
Main Components ◽  
The Relationship

The article deals with the problem of improving the stability of quality parameters in the milling of molds, which provides for minimizing deviations from the set values that meet the requirements of the product drawing. For this purpose, a block diagram of the milling operation was developed and decomposition was carried out, which allowed to identify such subsystems, “workpiece”, “machine — tool”, “tool”, “contact zone”. The factors that lead to a decrease in the parameters of the quality of the surfaces of the workpiece are determined. The developed block diagram allowed to establish the relationship between the main components of the technological system and the characteristics of the machining process.

Modeling of Drillstrings

2005 ◽  
Author(s):  
M. A. Elsayed ◽  
Chin Chin Phung
Keyword(s):  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Laboratory Data ◽  
Stability Diagram ◽  
Test Rig ◽  
Real Component ◽  
Reasonable Degree ◽  
Representative Model ◽  
The Stability

In this paper we show how a drillstring can be modeled in terms of limited numbers of masses and springs for the purpose of building a test rig. The model should represent the drillstring dynamics to a reasonable degree of accuracy. We will use the real component of the Frequency Response Function and the stability diagram as measures of dynamic similarity between the model and drillstring. We will also show how the chosen modes can be decoupled and used in obtaining the bit displacement. The decoupled modes will be used in a proposed test rig configuration that would increase flexibility in adding or removing modes from the system. Obtaining a representative model of the test rig is critical to our ability to extrapolate laboratory data into field applications.

RCSA-Based Method for Tool Frequency Response Function Identification Under Operational Conditions Without Using Noncontact Sensor

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Rong Yan ◽  
Xiaowei Tang ◽  
Fangyu Peng ◽  
Yuting Li ◽  
Hua Li
Keyword(s):  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Fem Simulation ◽  
Operational Conditions ◽  
Receptance Coupling ◽  
Substructure Analysis ◽  
Cutting Experiment ◽  
Receptance Coupling Substructure Analysis ◽  
The Stability

The stability lobe diagrams predicted using the tool frequency response function (FRF) at the idle state usually have discrepancies compared with the actual stability cutting boundary. These discrepancies can be attributed to the effect of spindle rotating on the tool FRFs which are difficult to measure at the rotating state. This paper proposes a new tool FRF identification method without using noncontact sensor for the rotating state of the spindle. In this method, the FRFs with impact applied on smooth rotating tool and vibration response tested on spindle head are measured for two tools of different lengths clamped in spindle–holder assembly. Based on those FRFs, an inverse receptance coupling substructure analysis (RCSA) algorithm is developed to identify the FRFs of spindle–holder–partial tool assembly. A finite-element modeling (FEM) simulation is performed to verify the validity of inverse RCSA algorithm. The tool point FRFs at the spindle rotating state are obtained by coupling the FRFs of the spindle–holder–partial tool and the other partial tool. The effects of spindle rotational speed on tool point FRFs are investigated. The cutting experiment demonstrates that this method can accurately identify the tool point FRFs and predict cutting stability region under spindle rotating state.

Relationship between harmonic balance method and non-linear output frequency response function approach

2007 ◽  
Vol 221 (12) ◽  
pp. 1533-1543 ◽  
Author(s):  
Z K Peng ◽  
Z Q Lang
Keyword(s):  
Frequency Response ◽  
Response Function ◽  
Harmonic Balance ◽  
Frequency Response Function ◽  
Harmonic Balance Method ◽  
Balance Method ◽  
Output Frequency ◽  
Non Linear ◽  
Harmonic Components ◽  
The Relationship

The current paper is concerned with the investigation of the relationship between the harmonic balance method (HBM) and the non-linear output frequency response function (NOFRF) approach in the analysis of non-linear systems. Both are applied to the Duffing's oscillator to demonstrate their relationships. The results reveal that, if the Volterra series representation of a non-linear system is convergent, the harmonic components calculated by the NOFRFs are a solution of the HBM. Moreover, the simulation studies show that, in the convergent cases, the NOFRF method can give more accurate results for the higher-harmonic components than the HBM. The relationship investigated in the current study between the two methods should help researchers and engineers to understand the HBM and the NOFRF methods.

Investigating Dynamics of Machine Tool Spindles under Operational Conditions

2011 ◽  
Vol 223 ◽  
pp. 610-621 ◽  
Author(s):  
O. Özşahin ◽  
Erhan Budak ◽  
H.N. Özgüven
Keyword(s):  
Machine Tool ◽  
Cutting Forces ◽  
Cutting Conditions ◽  
Response Functions ◽  
Input Output ◽  
Idle State ◽  
Operational Conditions ◽  
Stability Diagrams ◽  
Spindle Dynamics ◽  
The Stability

Chatter is one of the major problems in machining and can be avoided by stability diagrams which are generated using frequency response functions (FRF) at the tool tip. During cutting operations, discrepancies between the stability diagrams obtained by using FRFs measured at the idle state and the actual stability of the process are frequently observed. These deviations can be attributed to the changes of machine dynamics under cutting conditions. In this paper, the effects of the cutting process on the spindle dynamics are investigated both experimentally and analytically. The variations in the spindle dynamics are attributed to the changes in the bearing parameters. FRFs under cutting conditions are obtained through the input-output relations of the cutting forces and the vibration response which are measured simultaneously. Experimentally and analytically obtained FRFs are then used in the identification of the bearing parameters under cutting conditions. Thus, bearing properties obtained at idle and cutting conditions are compared and variations in their values are obtained.

In-Process Analysis of Machine Tool Structure Dynamics and Prediction of Machining Chatter

1976 ◽  
Vol 98 (1) ◽  
pp. 301-305 ◽  
Author(s):  
Toshimichi Moriwaki ◽  
Kazuaki Iwata
Keyword(s):  
Machine Tool ◽  
Structural Model ◽  
Process Analysis ◽  
Stability Limit ◽  
Shear Plane ◽  
Experimental Investigations ◽  
Machine Tool Structure ◽  
The Stability ◽  
Cutting Experiments ◽  
Theoretical Analyses

Theoretical and experimental investigations were carried out to identify the dynamics of a machine tool structure during cutting to predict the borderline of stability against the self-excited regenerative chatter. The validity of theoretical analyses in calculating the stability limit for conventional machining was confirmed by cutting experiments using a structural model. The model dynamics were identified during cutting under stable (non-chattering) cutting conditions by applying a technique of system identification based on time series analysis of the small random cutting force variations measured by a specially designed tool dynamometer and the corresponding minute vibrations. The experimentally obtained borderline of stability had a fairly good agreement with that calculated from the identified dynamics of the structure and the cutting dynamics, the latter being estimated from the static cutting data based on the so-called shear plane model.

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