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Displaying 26 - 44 of 44

Thermal Imaging of Metals in a Kolsky-Bar Apparatus

January 1, 2003
Author(s)
Eric P. Whitenton, Richard L. Rhorer, Howard W. Yoon, D Basak, Richard J. Fields, Lyle E. Levine, Timothy J. Burns
For materials testing at elevated temperatures, we describe the design and the development of a resistively heated Kolsky-bar apparatus. The temperature of the sample is determined by non-contact thermometry and the spatial temperature gradients in the

Regenerative Stability Analysis of Highly Interrupted Machining

May 1, 2002
Author(s)
Matthew A. Davies, Jon R. Pratt, Brian S. Dutterer, Timothy J. Burns
We discuss theoretical and experimental work that supports the use of very low radia immersion in the high-speed milling of difficult-to-machine materials, such as titanium alloys. Our theory is based upon modeling the cutting process by a kicked harmonic

Stability Prediction For Low Radial Immersion Milling

May 1, 2002
Author(s)
Matthew A. Davies, Jon R. Pratt, Brian S. Dutterer, Timothy J. Burns
Traditional regenerative stability theory predicts a set of optimally stable spindle speeds at integer fractions of the national frequency of the most flexible mode of the system. The assumptions of this theory become invalid for highly interrupted

On Repeated Adiabatic Shear Band Formation During High-Speed Machining

April 1, 2002
Author(s)
Timothy J. Burns, Matthew A. Davies
We compare the repeated adiabatic shear band formation that takes place at sufficient large cutting speeds in a number of materials during high speed machining operations with the more well known formation of a single shear band that often takes place at

The Precision Alignment of a Kolsky Bar Apparatus

January 1, 2002
Author(s)
Timothy J. Burns, Brian S. Dutterer, Michael Kennedy, Matthew A. Davies, Richard L. Rhorer
The modeling of machining processes is often limited by the availability of material data appropriate for the high strain rates and rapid heating associated with the metal cutting process. A new NIST facility - the pulse heated Kolsky bar apparatus - has

Thermomechanical Oscillations in Material Flow During High-Speed Machining

April 1, 2001
Author(s)
Matthew A. Davies, Timothy J. Burns
This paper presents a nonlinear dynamics approach for predicting the transition from continuous to shear-localized chip formation in machining. Experiments and a simplified one-dimensional model of the flow both show that, as cutting speed is increased, a

Regenerative Stablity Analysis of Highly Interrupted Machining

January 1, 2001
Author(s)
Matthew A. Davies, Jon R. Pratt, Brian S. Dutterer, Timothy J. Burns
We discuss theoretical and experimental work that supports the use of very low radia immersion in the high-speed milling of difficult-to-machine materials, such as titanium alloys. Our theory is based upon modeling the cutting process by a kicked harmonic

Calibrated Thermal Microscopy of the Tool-Chip Interface in Machining

August 1, 2000
Author(s)
Howard W. Yoon, Matthew A. Davies, Timothy J. Burns, Michael Kennedy
A critical parameter in predicting tool wear during machining and in accurate computer simulations of machining is the spatially-resolved temperature at the tool-chip interface. We describe the development and the calibration of a nearly diffraction

Calibrated Thermal Microscopy of the Tool-Chip Interface in Machining

April 1, 2000
Author(s)
Michael Kennedy, Matthew A. Davies, Howard W. Yoon, Timothy J. Burns
A critical parameter in predicting tool wear during machining and in accurate computer simulations of machining is the spatially-resolved temperature at the tool-chip interface. We describe the development and the calibration of a nearly diffraction

On the Bifurcation From Continuous to Segmented Chip Formation in Metal Cutting

February 6, 2000
Author(s)
Timothy J. Burns, Matthew A. Davies, Christopher J. Evans
We describe a new approach to modeling chip formation in orthogonal machining. Metal cutting is interpreted as a nonlinear dynamical process with thermomechanical feedback, which is similar in many ways to an open chemical reactor. As the cutting speed is

Micro-NCT of the Tool-Chip Interface in Machining

January 1, 2000
Author(s)
Timothy J. Burns, Matthew A. Davies, Michael Kennedy, Howard Yoon
Machining is a ubiquitous manufacturing process with tremendous economic impact. For example, Dr. Eugene Merchant, who is a founder of the scientific treatment fo machining processes, recently estimated that approximately 15 % of the value of all

The Stability of Low Radial Immersion Milling

January 1, 2000
Author(s)
Matthew A. Davies, Jon R. Pratt, Brian S. Dutterer, Timothy J. Burns
Traditional regenerative stability theory predicts a set of spindle speeds with locally optimum stability at integer fractions of the natural frequency of the most flexible mode of the system. The assumptions of this theory become invalid for highly

On the Bifurcation from Continuous to Segmented Chip Formation in Metal Cutting

March 4, 1998
Author(s)
Timothy J. Burns, Christopher J. Evans, Matthew A. Davies
We describe a new approach to modeling chip formation in orthogonal machining. Metal cutting is interpreted as a nonlinear dynamical process with thermomechanical feedback, which is similar in many ways to an open chemical reactor. As the cutting speed is

Nonlinear Dynamics Model for Chip Segmentation in Machining

November 30, 1997
Author(s)
Timothy J. Burns, Matthew A. Davies
We have developed a new model for chip formation in machining which includes a mechanism for thermomechanical feedback. This leads to an interpretation of metal cutting as a process which is similar in many ways to an open chemical reactor. As the cutting

On the Dynamics of Chip Formation in Machining Hard Metals

January 1, 1997
Author(s)
Matthew A. Davies, Timothy J. Burns, Christopher J. Evans
The results of orthogonal cutting tests on electroplated Nickel-Phosphorus (15% phosphorus) and AISI 52100 bearing steel are presented and compared. For both materials, chips become segmented at relatively low cutting speeds (0.3 m/s to 2 m/s) due to the

The dynamics of chip formation in machining

January 1, 1997
Author(s)
Matthew A. Davies, Christopher J. Evans, Timothy J. Burns
In this paper, we provide experimental, numerical and analytical evidence suggesting that the onset of segmented chip formation is the result of a Hopf bifurcation in the material flow. We modify the conventional one-dimensional model for orthogonal