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.

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.

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.

Investigation of Relation between Straightness and Cutting Force in CNC Turning Process

2015 ◽  
Vol 789-790 ◽  
pp. 812-820 ◽  
Author(s):  
Thararath Shansungnoen ◽  
Somkiat Tangjitsitcharoen
Keyword(s):  
Cutting Force ◽  
Cutting Speed ◽  
Rake Angle ◽  
Cutting Conditions ◽  
Turning Process ◽  
Nose Radius ◽  
Cnc Turning ◽  
Force Ratio ◽  
Cnc Turning Process ◽  
Tool Nose Radius

The objective of this research is to examine the relation between the straightness and the cutting force ratio during the CNC turning process. The cutting force is monitored and obtained by installing the dynamometer on the turret of CNC turning machine. The relation between the cutting force ratio and the straightness is investigated under the various cutting conditions, which are the cutting speed, the feed rate, the depth of cut, the tool nose radius and the rake angle. The experimentally obtained results showed that the straightness can be improved with an increase in cutting speed, tool nose radius and rake angle. The relation between the dynamic cutting force and straightness profile can be proved by checking the frequency of the cutting force in frequency domain with the use of the Fast Fourier Transform (FFT), which is the same as the straightness profile. Hence, the cutting force ratio can be used to predict the straightness during the cutting regardless of the cutting conditions. The cutting force ratio is proposed to predict the straightness during turning process by employing the exponential function for the sake of straightness. The multiple regression analysis has been utilized to calculate the regression coefficients of the in-process prediction of straightness model by using the least square method at 95% confident level. It has been proved by the cutting tests that the in-process straightness can be predicted during the cutting within ±10% measured straightness with the high accuracy of 91.85%.

Improved Methods for the Prediction of Chatter in Turning, Part 3: A Generalized Linear Theory

1990 ◽  
Vol 112 (1) ◽  
pp. 28-35 ◽  
Author(s):  
I. E. Minis ◽  
E. B. Magrab ◽  
I. O. Pandelidis
Keyword(s):  
Machine Tool ◽  
Linear Theory ◽  
A Priori ◽  
Cutting Conditions ◽  
Depth Of Cut ◽  
Orthogonal Turning ◽  
Machine Tool Structure ◽  
Wide Range ◽  
Machining System ◽  
The Stability

The linear theory of chatter has been generalized to any machining configuration without a priori assumptions on either the direction of the cutting force or the modal directions of the machine tool structure. Furthermore, the effects of the tool’s orientation on the stability of the machining system are directly expressed by its closed loop characteristic equation. Using experimental measurements for the dynamics of both the machine tool structure and the cutting process obtained previously under actual cutting conditions, the proposed theory is applied to two cases of orthogonal turning. The resulting predictions of the critical depth of cut are in excellent agreement with the measurements of actual chatter for a wide range of cutting conditions.

scholarly journals Investigation of Surface Quality for Minor Scale Diameter of Biodegradable Magnesium Alloys during the Turning Process Using a Different Tool Nose Radius

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1174
Author(s):  
Sophal Hai ◽  
Hwa-Chul Jung ◽  
Won-Hyun Shim ◽  
Hyung-Gon Shin
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Feed Rate ◽  
Cutting Parameters ◽  
Spindle Speed ◽  
Turning Process ◽  
Nose Radius ◽  
Machined Surface ◽  
Tool Nose Radius

The main objective of the study is to analyze the various cutting parameters to investigate the surface quality of the minor scale diameter of magnesium alloy in the dry turning process using a different tool nose radius (r). The surface roughness (Ra) was gauged, and micro-images produced by scanning electron microscopy (SEM) were reviewed to evaluate the machined surface topography. The analysis of variance (ANOVA), linear regression model and signal-to-noise (S/N) ratio were applied to investigate and optimize the experimental conditions for surface roughness. The study results imply that the feed rate and tool nose radius significantly affected the surface quality, but the spindle speed did not. The linear regression model is valid to forecast the surface roughness. The cutting parameters for optimum surface quality are a combination of a spindle speed of 710 rpm, a feed rate of 0.052 mm/rev and a tool nose radius of 1.2 mm. The machined surface topography contains the feed marks, micro-voids, material side and material debris, but they become smaller and decrease at a lower feed rate, larger tool nose radius and higher spindle speed. These results show the good surface quality of magnesium alloys in a dry turning process, which could be applied in implant, orthopedic and trauma surgery.

Global stability result for parabolic Cauchy problems

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mourad Choulli ◽  
Masahiro Yamamoto
Keyword(s):  
New York ◽  
Partial Differential Equations ◽  
Global Stability ◽  
Classical Problem ◽  
Stability Result ◽  
Cauchy Problems ◽  
Smooth Solutions ◽  
Linear Partial Differential Equations ◽  
Ill Posed ◽  
The Stability

AbstractUniqueness of parabolic Cauchy problems is nowadays a classical problem and since Hadamard [Lectures on Cauchy’s Problem in Linear Partial Differential Equations, Dover, New York, 1953], these kind of problems are known to be ill-posed and even severely ill-posed. Until now, there are only few partial results concerning the quantification of the stability of parabolic Cauchy problems. We bring in the present work an answer to this issue for smooth solutions under the minimal condition that the domain is Lipschitz.

Stability of a Rigid Body With an Oscillating Particle: An Application of MACSYMA

1985 ◽  
Vol 52 (3) ◽  
pp. 686-692 ◽  
Author(s):  
L. A. Month ◽  
R. H. Rand
Keyword(s):  
Angular Velocity ◽  
Rigid Body ◽  
Classical Problem ◽  
Moment Of Inertia ◽  
Model Parameters ◽  
Stability Chart ◽  
The Stability ◽  
Transition Curves ◽  
Minimum Moment ◽  
Small Angular Velocity

This problem is a generalization of the classical problem of the stability of a spinning rigid body. We obtain the stability chart by using: (i) the computer algebra system MACSYMA in conjunction with a perturbation method, and (ii) numerical integration based on Floquet theory. We show that the form of the stability chart is different for each of the three cases in which the spin axis is the minimum, maximum, or middle principal moment of inertia axis. In particular, a rotation with arbitrarily small angular velocity about the maximum moment of inertia axis can be made unstable by appropriately choosing the model parameters. In contrast, a rotation about the minimum moment of inertia axis is always stable for a sufficiently small angular velocity. The MACSYMA program, which we used to obtain the transition curves, is included in the Appendix.

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