bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Rake Face Design on Cutting Tool Temperature Distributions
Authors: Wright P. K. , McCormick S. P. , Miller T. R.
Published: July 2009

Turning experiments have been carried out on a low carbon iron using steel tools of different side rake face geometry. Temperature distributions have been determined using a recently developed metallographic method. It has been found that when using tools which have a controlled chip-tool contact length of 0.5 mm. the temperatures are ∼30 per cent lower than when using conventional, 6 deg rake tools and, as a result, tool life is longer. Theoretical equations are described which allow the calculation of the temperature distribution along the chip tool interface and the tribological conditions in this region are also considered in detail. There is good agreement between the calculated and measured temperature distributions.
Monitoring and Controlling the E.D.M. Process
Authors: Bhattacharyya S. K. , El-Menshawy M. F.
Published: July 2009

Extensive investigations were carried out to study the emitted radiation during the E.D.M. process. It was found that radiation from the region of the gap between the electrode (tool) and the workpiece is significantly different when the following four conditions: open voltage, effective discharge (sparking), arc and short circuit occur during the E.D.M. process. The sparking condition is accompanied by a comparatively high radiation level at radio frequencies above 1 MHz. During arcing, however, although relatively low radiation takes place below 0.5 MHz, there is practically no radio frequency emission at all. However, the E.D.M. process could be monitored and optimized from the emitted radio frequency signals. The emitted radio signals could be employed to develop an adaptive control system for E.D.M. machines. The reported work includes apparatus, circuits and methods for monitoring the E.D.M. process and controlling such a process in accordance with the monitoring carried out.
Tool Wear by Solution: A Quantitative Understanding
Authors: Kramer B. M. , Suh N. P.
Published: July 2009

The mechanism controlling the crater wear of single phase carbide cutting tool materials in the high speed cutting of steel has been identified. A simple model has been developed to describe the wear process. Cutting tests employing inserts coated with Group IVB and VB carbides show excellent agreement with the relative wear rates predicted from the thermodynamic properties of the tool-work system. Thus, for the first time, quantitative calculation of the relative wear rates of various potential tool materials from thermodynamic data is possible. The technique is believed to have broad application to other tool-work combinations. Implications for future research are discussed.
Tensile Properties of Triaxially Woven Fabrics Under Biaxial Loading
Authors: Schwartz P. , Fornes R. E. , Mohamed M. H.
Published: July 2009

Classical results in the behavior of woven fabrics are extended to the case of fabrics having three planar, nonorthogonal axes of symmetry (triaxial). The biaxial loading analysis due to Grosberg is extended to the loading of triaxial fabrics in the machine and cross-machine directions in an attempt to predict fabric modulus during the crimp removal stage. Preliminary experimental results showing reasonably good agreement with moderately open fabrics are given. In addition, relationships are developed to allow the construction of conventional fabrics which are equivalent to triaxial fabrics in terms of cover factor and intersections or interfacings per unit area.
Reference-Pulse Circular Interpolators for CNC Systems
Authors: Koren Y. , Masory O.
Published: July 2009

Interpolation techniques for CNC manufacturing systems are either of the Reference-Pulse or Reference-Word type. Reference-Pulse interpolations emit a sequence of pulses as reference signals to the control loops, whereas Reference-Word interpolators provide binary words as references to Sampled-Data control loops. In the present paper, a number of Reference-Pulse interpolation methods are described, all of which function in an online iterative mode controlled by an external interrupt source. These methods are compared in terms of accuracy, maximum radius, uniformity of feedrate along the circular path, and maximum feedrate attainable. Selection of the appropriate interpolation method is found to depend on the specific application. Reference-Word interpolators will be covered in a subsequent paper.
Torque and Stress Balanced Design of Helically Armored Cables
Authors: Knapp R. H.
Published: July 2009

A new linear model of the mechanical behavior of helically armored cables is introduced. This model can be used to establish the conditions necessary to achieve a torque balanced cable construction and the requirements for equal load sharing among the armoring wires. Existing linear models are unable to accomplish this and more exact nonlinear formulations are not readily usable. It is recognized that a cable model is needed which more accurately describes the physical behavior of cables and yet is capable of solution by hand-calculation. This becomes particularly important in preliminary design where many other variables are also involve. The proposed cable model is tested for accuracy by comparison with a manufactured cable shown to be torque balanced.
The Grinding of Workpieces Exhibiting High Adhesion. Part 1: Mechanisms
Authors: Yossifon S. , Rubenstein C.
Published: July 2009

Three distinct grinding mechanisms have been found to occur when 304 L stainless steel is ground by alumina wheels. The first results in the grits becoming worn by attritious wear and occurs when temperatures in the grinding zone are relatively high, the second occurs at lower grinding temperatures and results in isolated, tiny areas of workpiece material adhering to grits while the third becomes manifest at relatively low grinding temperatures and results in areas of the wheel, large in comparison to the size of a grit, being covered by adherent workpiece material. Previous proposals advanced to explain metal build-up on the grinding wheel are shown to be inadequate and the phenomenon of large-scale metal transfer to the grinding wheel is shown to be related to the ductility of the workpiece along with the degree of protection conferred by the oxide of the workpiece material. This explanation is confirmed by grinding experiments performed on a series of oxide-resistant workpieces ground in air and, in particular, by the grinding of mild steel in an argon atmosphere under which conditions large-scale transfer of workpiece material to the wheel occurred.
The Grinding of Workpiece Materials Exhibiting High Adhesion. Part 2: Forces
Authors: Yossifon S. , Rubenstein C.
Published: July 2009

Equations expressing the dependence of the force components on grinding parameters and on the fraction of the wheel surface area over which workpiece material adheres during the grinding of workpiece materials which exhibit high adhesion are derived. These are shown to express the experimentally observed relations between the force components for each of the three grinding mechanisms which occur when this class of workpiece is ground. When large scale adhesion of workpiece material to the wheel surface occurs and more than five percent of the wheel surface is occupied by transferred material, the force components arise in large measure as a result of the forces generated through this metal/metal contact.
Optimization Analysis of Automated Assembly Systems
Authors: Hitomi K. , Yokoyama M.
Published: July 2009

Optimization analysis for maximizing the total profit of an automated assembly system consisting of automated assembly machines and operators was performed. In this analysis, concepts of two kinds of breakdowns, which depend on accuracy of parts and on machine running speed were introduced. Based on basic decision variables—accuracy of parts, machine running speed, and number of operators, profit rate of the automated assembly system was maximized through dynamic programming, and an optimizing algorithm for the maximum profit rate was developed with a numerical example.
Some Investigations Into Machining With Driven Rotary Tools
Authors: Venuvinod P. K. , Lau W. S. , Reddy P. Narasimha
Published: July 2009

Experimental studies have been conducted with driven rotary tools on various work materials, using specially constructed test rigs. The studies include the effect of rotary speed on the geometry, the kinematics and the mechanics of chip formation. The data are analyzed, using the concept of equivalent angle of obliquity. Hitherto unknown and extraordinary effects on the chip formation have been noted which lead to new modes of rotary machining and the expansion of the scope of rotary machining.
A Semi-Empirical Solution to Upset Forging
Authors: Dadras P.
Published: July 2009

A simple, semi-empirical approach for the determination of elastic zone, bulge profile, and load-displacement curve for the upsetting of cylindrical billets has been proposed. Stress distribution in the billet has been determined, and the effects of process and material parameters have been investigated. It has been shown that the size of the elastic zone is dependent on the ratio of the initial yield strength to the flow stress of the material (σy/σo), becoming smaller as (σy/σo) decreases. Also, a substantial growth of the elastic zone with friction is noticed.
Application of the Regeneration Spectrum Method to Wheel Regenerative Chatter in Grinding
Authors: Srinivasan K.
Published: July 2009

A convenient stability analysis technique for the approximate computation of wheel regenerative chatter growth rates in cylindrical grinding processes is presented. For such processes, the locations of the roots of the system characteristic equation in the complex plane are simply related to a function of frequency, termed the regeneration spectrum, which is easily determined. The usefulness of the regeneration spectrum method is illustrated by applying it to study the dependence of chatter growth rates on grinding conditions and to evaluate the effectiveness of changes in the machine structure in improving chatter behavior, for example cases of wheel regenerative chatter.
Rigid-Plastic Finite-Element Analysis of Plane Strain Rolling
Authors: Li Guo-Ji , Kobayashi S.
Published: July 2009

The plane-strain rolling problem was solved by the rigid-plastic finite-element method based on the infinitesimal theory of plastic deformation. Both nonsteady-state solutions and steady-state solutions were obtained. The velocity field in the deforming material and the external forces along the arc of contact were obtained. From these quantities, roll separating force, roll torque, and roll pressure distributions, as well as stress and strain fields, were calculated. A series of cases with different dimensions and material properties were analyzed and the results were compared with experiments found in the literature.
Shape Changes in the Upsetting of Slender Cylinders
Authors: Schey J. A. , Venner T. R. , Takomana S. L.
Published: July 2009

Mild steel and aluminum alloy cylinders were incrementally upset with good lubrication and with sticking friction, and the development of shape was followed by measuring the diameters of the barrel and the contact face. These dimensions changed according to a power law as a function of reduction and initial diameter-to-height ratio of the specimen. Formulas are given for predictive calculations of barrelled dimensions, and these were found to be reasonably applicable also to hot forging. The expansion of the original end face was highly sensitive to friction and the material’s strain hardening characteristics, and could not be generalized.
Tensile Fracture of Drawn Copper and Mild Steel
Authors: Thomsen E. G.
Published: July 2009

Annealed OFHC copper and SAE 1018 steel were reduced by multipass drawing from diameters of 25.4 mm (and smaller) to 11.8 mm. A comparison was made of the experimental draw stresses and those calculated by Sachs’ and Avitzur’s equations and fair agreement exists. The drawn bars were subsequently reduced in diameter by 10 percent in order to provide gage sections and then were pulled in tension to fracture. It was found that in multipass draws some work softening occurs. The oxygen-free copper showed indications that fracture was initiated at the center of the specimen. The internal fracture grew to the near shape of a sphere and separation did not occur until the load had almost decreased to zero. The mild steel apparently also fractured in the center, but complete separation took place immediately after the tensile stress reached its maximum. The fracture theories of Latham and Cockcroft, as well as that of Chen and Kobayashi, were examined and it was found that fair agreement existed. It was also found that for these particular tests, the maximum tensile stress criterion gave more convincing results.
The Prediction of Surface Accuracy in End Milling
Authors: Kline W. A. , DeVor R. E. , Shareef I. A.
Published: July 2009

In the end milling process, the cutting forces during machining produce deflection of the cutter and workpiece which result in dimensional inaccuracies or surface error on the finished component. A previously developed mathematical model for the cutting force system in end milling is combined with models for cutter deflection and workpiece deflection so that the surface error profile may be predicted from the machining conditions and geometry and material properties of the cutter and workpiece. Machining experiments are performed on rigid and flexible workpieces of 7075 aluminum to verify the ability of the models to predict surface error. The model predicted surface error profiles are accurate both in magnitude and shape with the difference between measured and predicted surface errors ranging from 5 to 15 percent. This approach for the prediction of surface errors provides a useful aid for the analysis of a variety of end milling process design and optimization problems.
A Study of Metal Flow Ahead of Tool Face With Large Negative Rake Angle
Authors: Kita Y. , Ido M. , Kawasaki N.
Published: July 2009

Although the chip formation mechanism by a tool having a large negative rake angle is not well known, it is very important to make the process clear in order to get high quality in finished surfaces. In this paper, the behavior of material ahead of a tool face with a large negative rake angle is examined by means of low speed machining on lead. The deformation process of the material is investigated by the deformation study combining a finite element method with a grid line method. During cutting, the deformation process of grid lines which were drawn on the sides of testpieces was observed through a side glass which restricted the side flow of material. Cutting force was measured by a dynamometer consisting of an elongated octagonal ring with strain wire gages. As a result it was found that the shear stress on the slip line of maximum increment of shear strain is nearly constant, but the compressive stress changes along the line. It was concave near the top of cutting edge and convex near the surface of the test piece. The position of the change of polarity in the slope shifted depending on the rake angle of the tool. This phenomenon is considered to have close relation with the stagnant tip, which decides not only the size of chip, but also whether or not a chip will be formed. Flow lines of material and the deformed region ahead of tool faces with different negative rake angles were also obtained and they were compared with each other.
Application of Plastic Boundary Layer Theory to Metal Machining
Authors: Jackson P. S. , Wright P. K.
Published: July 2009

In the metal machining operation, material is deformed at high rates in thin plastic zones. This paper explores the possibility that the features of such shear zones can be described by a theory for plastic boundary layers. The analysis draws on Oldroyd’s solution for the two-dimensional plastic flow of a Bingham solid over a flat knife. The way in which such a solution can be adapted to both the secondary and primary deformation zones in machining is described. A theoretical equation is derived that uses material properties to predict the tool-face pressure gradient along the contact length. An analysis for brass gives very good agreement between this approach and the experimental data for the tool-face pressure gradient obtained by Rowe and Wilcox.
An Adaptive Pressbrake Control Using an Elastic-Plastic Material Model
Authors: Stelson K. A. , Gossard D. C.
Published: July 2009

An adaptive controller for a pressbrake has been designed, built, and tested. The controller measures force and displacement during the early part of the bend cycle to estimate workpiece parameters. These parameters are used in an elastic-plastic material model to predict the correct final punch position to yield the desired unloaded angle. A microcomputer is used to control a Cincinnati CB90 hydraulic pressbrake. Data acquisition and computation times are short enough to bend a minimum flank angle of 15 deg using the standard forming rate of 6.7 mm/s (16 in./min) and a 25 mm (1 in.) V-die. Errors in flank angle were less than 1.5 deg in all cases.
Robotic Fabric Handling for Automating Garment Manufacturing
Authors: Parker J. K. , Dubey R. , Paul F. W. , Becker R. J.
Published: July 2009

This paper presents the potential use of a robotic end-effector for acquiring single plies from a stack of fabrics. This type of end-effector would be required to integrate robots into present-day garment manufacturing operations. Two design concepts, pins and temporary adhesion, were shown experimentally to successfully acquire a single fabric ply from a stack of plies approximately 95 percent of the time. These tests were equally successful on both woven and knit fabrics. Although the experiments were restricted to small square fabric plies, the feasibility of using a robotic end-effector to acquire single plies from a stack of fabrics was demonstrated.
Automatic Moisture Sensor for Measurement and Control of Cotton Ginning Processes
Authors: Waldie A. H. , Hughs S. E. , Gillum M. N.
Published: July 2009

Cotton fiber moisture content is one of the most important factors that affects the operation of the cotton ginning process. A system has been developed that measures cotton’s dielectric constant and density with sufficient accuracy to indicate moisture content of the fiber during processing. An electronic capacitor and a pneumatic density sensor supply measurements to a microprocessor which combines them into a predicted moisture content. Tests showed that these predicted readings are more precise than conventional oven-moisture determinations and that they can be used for process control in the ranges from 6.5- to 12-percent moisture content.
Adaptive Control in Machining—A New Approach Based on the Physical Constraints of Tool Wear Mechanisms
Authors: Yen D. W. , Wright P. K.
Published: July 2009

An optimization procedure for adaptive control based on the physical constraints of the machining process is proposed. Three different modes of tool failure have been examined and constraints for each mode of failure identified accordingly. A mapping procedure has then been used to transform these constraints into a control variable space and obtain a “safe working range.” The optimum working conditions are determined in terms of the control variables (cutting speed and feed rate) based on a chosen performance index (metal removal rate, in this case). Also, further consideration of time-varying situations such as tool wear and engage-exit conditions can be included in this formulation. Several numerical examples are presented for the identification of the dominant modes of failure, in particular, experimental cases. The results are in good agreement with the experimental data available.
Chatter Vibration of Lathe Tools. Part 1: General Characteristics of Chatter Vibration
Authors: Marui E. , Ema S. , Kato S.
Published: July 2009

The primary chatter vibration of turning tools is investigated experimentally. The vertical displacement of the turning tool and the fluctuating cutting force in the primary chatter vibration are measured simultaneously to investigate the characteristics and the resulting vibration mechanism, when cutting a top of the square thread of mild steel or cast iron. As a result, it is clarified that the relief angle varies widely with the vibration of the turning tool, the primary chatter vibration is self-excited, and the vibratory energy is provided by the frictional force acting in the contact between the tool flank and workpiece.
Chatter Vibration of Lathe Tools. Part 2: On the Mechanism of Exciting Energy Supply
Authors: Marui E. , Ema S. , Kato S.
Published: July 2009

First, the development of the chatter vibration is observed using several turning tools having various cutting edge configurations and in the conditions in which there are different levels of interference between the flank of the tool and the workpiece. Next, the exciting energy provided by the contact of tool flank and workpiece is calculated using an interference model at the tool flank which includes an elastic deformation of workpiece. This theoretical result agrees qualitatively with the experimental result concerning the development of chatter vibration. The energy-supplying mechanism in primary chatter vibration of a turning tool is clarified by examining the foregoing results collectively.
Performance Characteristics of Absorption Cooling Cycle Operated by Low Thermal Potential Energy Sources
Authors: Yaron I. , Borde I. , Jelinek M.
Published: July 2009

The possibility is investigated of using freon refrigerants and organic solvent systems in absorption refrigeration installations, utilizing low thermal-potential energy sources, for refrigeration and direct contact cooling to temperatures of or below 0°C. A detailed thermodynamic analysis by means of a simulation model of the cycle for several refrigerant-absorbent systems has delineated the operating range and dependence of the variations of the coefficient of performance and of the circulation ratio upon generator and condenser temperatures. The performance characteristics of freon - dibutyl phthalate and freon - dimethyl ether of tetraethylene glycol systems were compared.
Instability Parameter for Machined Parts
Authors: Israeli A. , Benedek J.
Published: July 2009

The production of precision parts requires manufacturing processes which produce low residual stresses. This study was designed to investigate the parametric relationship between machining processes and residual stress distribution. Sets of steel specimens were single point turned at different feeds. The residual stress profiles of these specimens were monitored, using a continuous etching technique. A “Specific Instability Potential” parameter, derived from the strain energy of the residual stresses, was found to relate directly to the machining parameters. It is suggested that the Specific Instability Potential can be used as a parameter for specifying processing operations.
Further Developments in Applying the Finite Element Method to the Calculation of Temperature Distributions in Machining and Comparisons With Experiment
Authors: Stevenson M. G. , Wright P. K. , Chow J. G.
Published: July 2009

The finite element program developed in previous work [1] for calculating the temperature distributions in the chip and tool in metal machining has been extended in its range of application. Specifically, the program no longer needs a flow field as input and it can accommodate a wide range of shear angle and contact lengths. An important feature of this paper is that temperature fields from the finite element method have been compared with temperatures obtained with a previously described metallographic method [7]. This is the first time these two techniques have been used for the same machining conditions and the comparisons are very good.
Application of FEM Modeling to Simulate Metal Flow in Forging a Titanium Alloy Engine Disk
Authors: Oh S. I. , Park J. J. , Kobayashi S. , Altan T.
Published: July 2009

The isothermal forging of a titanium alloy engine disk is analyzed by the rigid-viscoplastic finite element method. Deformation mechanics of the forging process are discussed, based on the solution. The effects of temperature and heat conduction on the forging process are also investigated by coupled thermo-viscoplastic analysis. Since the dual microstructure / property titanium disk can be obtained by controlling strain distribution during forging, the process modeling by the finite element method is especially attractive.
Surface Texture and Machining Conditions. Part 2: Development of Mathematical Model Based Upon Pattern Recognition
Authors: Villa A. , Murari G. , Levi R.
Published: July 2009

Logic foundations expounded in Part 1 are applied to development of a mathematical model describing profile generation in face milling. A pattern recognition procedure is developed, capable of locking onto proper reference points on the profile in terms of tool mark characteristics and identifying model parameters. Construction of the reference locating algorithm is examined in detail, and some aspects of application covering also profile reconstruction are discussed in the light of test results.
Modal Analysis of Machine Tool Structures Based on Experimental Data
Authors: Eman K. F. , Kim K. J.
Published: July 2009

The basic problem in modal analysis of machine tool structures is the extraction of modal parameters from the measured transfer function data. Conventionally this task is performed in two steps. The transfer function is determined using a Digital Fourier Analyzer followed by a suitable curve fitting procedure. In order to avoid the inherent problems associated with these procedures a new approach for modal analysis is proposed in this paper. Anticipating the stochastic nature of the systems excitation and response Modified Autoregressive Moving Average Vector models (MARMAV) are proposed. The modeling procedure yields a parametric representation of the structural behavior allowing the extraction of the modal information in one step, directly, rather than in two as in the conventional approaches. The mathematical foundation for the approach is given along with its application to a simulated three-degree-of-freedom system and a knee type milling machine. The newly proposed procedure is commensurate to the existing ones in light of the computational efforts involved; however, it eliminates the subjective judgment of the analyst since the modeling procedure is based on rigorous statistical adequacy checks. Finally, the proposed approach is amenable for implementation in a computer-based machine tool structural dynamics analyzer.
Optimal Infeed Control for Accelerated Spark-Out in Plunge Grinding
Authors: Malkin S. , Koren Y.
Published: July 2009

An optimal infeed control policy is proposed to minimize the cycle time in cylindrical plunge grinding. As compared with conventional infeed control consisting of roughing followed by spark-out, the proposed infeed control policy accelerates the spark-out by reducing the time required to recover the accumulated elastic deflection in the system and to reduce the infeed velocity to its final required value. This optimal infeed control policy is particularly advantageous for grinding systems having a long characteristic time constant. A practial method is described for implementing the optimal infeed control policy based upon direct measurement of the radial allowance remaining on the workpiece.
The Effect of Metered Starve Feeding on the Performance of a Small Extruder
Authors: Isherwood D. P. , Pieris R. N. , Kassatly J.
Published: July 2009

Experiments have been carried out on a 38-mm diameter single screw extruder in which the machine was fed at a controlled rate below its capacity (the starve fed mode). It was found that, for three different polymers in granular form, the die pressure fluctuations and specific power consumption reduced for limited amounts of starvation and these improvements were associated with a smoother melting profile. Melt initiation was delayed but once it had started subsequent melting was rapid. Higher levels of starvation with granules and also modest degrees of starvation of a polyethylene powder had deleterious effects. The observed behavior is discussed in terms of the increased solid bed mobility allowed by the loosely packed material in the screw channel.
Heat Transfer Aspects of Nonisothermal Axisymmetric Upset Forging
Authors: Dadras P. , Wells W. R.
Published: July 2009

A finite difference solution for the transient heat transfer during axisymmetric upset forging has been developed. The interfacial film between the die and the billet has been included in the analysis, and all modes of heat transfer have been taken into account. The results of a parallel experimental study have also been presented. The effects of geometrical and physical characteristics of the billet and the die on the heat transfer process, particularly on die heating, have been systematically investigated.
Space Station Productivity from Information Technology
Authors: Anderson J. L.
Published: July 2009

A space station will involve the formation and operation of an assembly of humans and machines with the intent of achieving sustained operation in space for a period of 10–20 years. A major goal of space station technology efforts is to enable both the initial and evolutionary productivity of the space station. Because a space station is expected to be an information-rich system, technologies that improve the acquisition, processing, and interpretation of information will have a high leverage on station productivity. Specific information technology functions and requirements that promote human–machine productivity for a space station are examined.
Space Station Technology—Challenge and Opportunity
Authors: Olstad W. B.
Published: July 2009

As the start-up of development of a permanent U.S. space station draws near, the technologist is faced with the responsibility of delivering to the designer a product that is “ready” so as to assure effective handover at a minimum level of technical risk or residual development cost. At the same time, the technologist is asked to provide as broad a range of options as possible for the designer’s consideration. All this must be done for a set of requirements and constraints that are as yet vague. These uncertainties make the planning process and management decisions difficult. However, NASA’s approach has been to call on the collective wisdom of the aerospace community through establishment of a Space Station Technology Steering Committee (SSTSC). This in-house NASA committee represents all Centers plus the JPL and covers all significant discipline areas and the experimental spectrum from basic research to system development. Currently ten working groups report to the Committee. A number of issues have been pinpointed by the Committee while identifying the desired level of technology for incorporation in a U. S. space station, both initially and as it grows in size, capability, and utility. These issues revolve around the needs to anticipate requirements, consider minimization of life-cycle costs, engender station growth, maximize efficiency of the technology “hand-over” process, permit on-orbit maintenance and repair, facilitate useful operational and scientific activities, and use space station development as a deliberate mechanism to advance technologies in areas selected to bring major benefit to the United States in general, as well as the space station in particular.
Satellite Servicing by Teleoperators
Authors: French R. , Boyce B.
Published: July 2009

The Teleoperator Maneuvering System (TMS) will initially be a Shuttle-launched ground-based, satellite servicing vehicle controlled by man-in-the-loop. During Space Station implementation, it will be used to assist the assembly and placement of the various Space Station elements as well as to provide logistics module transportation from the Shuttle to the Space Station. It will eventually be based at the Space Station to support satellite viewing, spacecraft and payload placement and retrieval functions, and to provide support of science or materials processing free-flying platforms. Various satellite servicing examples with the use of the TMS from the Space Station and/or the Space Shuttle are provided in this paper. Concepts for the number of TMS and the type of basing required at the Space Station are also reviewed. Specific station accommodations must await definition of the emerging station configurations.
Identification of the Joint Structural Parameters of Machine Tool by DDS and FEM
Authors: Yuan J. X. , Wu X. M.
Published: July 2009

A unique methodology is proposed to identify the joint structural parameters of the machine tool by combining the Dynamic Data System (DDS) methodology with the Finite Element Method (FEM). The structural parameter identification of a simple system with complete modal matrix is introduced together with the modal analysis by the DDS method. The simulation study of a two degree-of-freedom system shows the high accuracy of the identification procedure. The identification of joint parameters of a general system with an incomplete mode shape is analyzed next. The condensation and digital filtering techniques are developed for this purpose. In a shaft model experiment the joint parameters are identified when the response data at boundary points are difficult to be measured. Furthermore, a column model experiment revealed the ability of the proposed identification technique to deal with a large number degree-of-freedom system.
A Transport-Diffusion Equation in Metal Cutting and its Application to Analysis of the Rate of Flank Wear
Authors: Kannatey-Asibu E.
Published: July 2009

A two-dimensional transport-diffusion equation is derived for diffusion in metal cutting by an extension of Fick’s second law. The analysis considers the dynamics of the cutting process and thus offers a comprehensive representation of the diffusing species in the workpiece and the chip. A relationship for the rate of flank wear is derived considering adhesion and diffusion as the major modes of wear on the tool flank. It is based on the mechanics of the wear process, friction and diffusion, taking into account the regenerative effects of wear, temperature, and friction force. Based on the simulated results of the analysis, a new criterion is proposed for determining tool life.
An Analytical Model of Cutting Dynamics. Part 1: Model Building
Authors: Wu D. W. , Liu C. R.
Published: July 2009

A mathematical model of machining chatter has been developed through an analytical approach in order to predict dynamic cutting force from steady-state cutting tests. The model is derived from a pseudo-static geometric configuration of the cutting process by taking into account the fact that the mean friction coefficient fluctuates dynamically responding to variation of the relative speed on the chip-tool interface. The force functions through this derivation can be used to explain all three basic mechanics associated with chatter vibration, namely, velocity dependent, regenerative, and mode coupling effects.
An Analytical Study of Deformation Behavior of Porous Metals in Uniaxial Tension and Compression
Authors: Oyane M. , Shima S. , Sato T. , Tada Y.
Published: July 2009

On the basis of an upper-bound approach, deformation behavior of porous metals is considered. A model for porous metals is employed to describe a kinematically admissible velocity field for uniaxial deformation. By minimizing the total energy dissipation rate obtained from the velocity field, the yield strength, deformation behavior of porous metals, and also distortion of pores are evaluated. In the analysis, porosity, geometry of pores, and environmental hydrostatic pressure are taken into consideration. Calculated results are compared with experimental and/or other theoretical ones and show good agreement.
An Analytical Approach to the Problem of Core Fracture During Extrusion of Bimetal Rods
Authors: Avitzur B. , Wu R. , Talbert S. , Chou Y. T.
Published: July 2009

The process of core fracture in bimetals during extrusion was reexamined. The new analysis, based on the upper-bound theorem in limit analysis, eliminated the lengthy numerical computations employed in the previous work [1]. The criterion for core fracture was derived and discussed.
Direct Upper-Bound Solution and Finite Element Approach to Round-To-Square Drawing
Authors: Boe¨r C. R. , Webster W. D.
Published: July 2009

The paper presents a direct comparison between two modeling techniques of metal forming processes, in the present case wire drawing. The two methods have the same basic approach in using the Upper-Bound Theorem but the solution methods are fundamentally different. One method is a direct analytical solution requiring the knowledge of a kinematically admissible velocity field, the other method uses a finite element approach and calculation of the velocities at the nodes of the mesh. Both methods minimize the power required. The theoretical fundamentals of the two methods, the solution approaches and the results are presented and compared. The advantages and disadvantages of both methods are also analysed.
Highlights of the DARPA Advanced Machining Research Program
Authors: Komanduri R. , Flom D. G. , Lee M.
Published: July 2009

Results of a four-year Advanced Machining Research Program (AMRP) to provide a science base for faster metal removal through high-speed machining (HSM), high-throughput machining (HTM) and laser-assisted machining (LAM) are presented. Emphasis was placed on turning and milling of aluminum-, nickel-base-, titanium-, and ferrous alloys. Experimental cutting speeds ranged from 0.0013 smm (0.004 sfpm) to 24,500 smm (80,000 sfpm). Chip formation in HSM is found to be associated with the formation of either a continuous, ribbon-like chip or a segmental (or shear-localized) chip. The former is favored by good thermal properties, low hardness, and fcc/bcc crystal structures, e.g., aluminum alloys and soft carbon steels, while the latter is favored by poor thermal properties, hcp structure, and high hardness, e.g., titanium alloys, nickel base superalloys, and hardened alloy steels. Mathematical models were developed to describe the primary features of chip formation in HSM. At ultra-high speed machining (UHSM) speeds, chip type does not change with speed nor does tool wear. However, at even moderately high speeds, tool wear is still the limiting factor when machining titanium alloys, superalloys, and special steels. Tool life and productivity can be increased significantly for special applications using two novel cutting tool concepts – ledge and rotary. With ledge inserts, titanium alloys can be machined (turning and face milling) five times faster than conventional, with long tool life (~ 30 min) and cost savings up to 78 percent. A stiffened rotary tool has yielded a tool life improvement of twenty times in turning Inconel 718 and about six times when machining titanium 6A1-4V. Significantly increased metal removal rates (up to 50 in.3/min on Inconel 718 and Ti 6A1-4V) have been achieved on a rigid, high-power precision lathe. Continuous wave CO2 LAM, though conceptually feasible, limits the opportunities to manufacture DOD components due to poor adsorption (~ 10 percent) together with high capital equipment and operating costs. Pulse LAM shows greater promise, especially if new laser source concepts such as face pump lasers are considered. Economic modeling has enabled assessment of HSM and LAM developments. Aluminum HSM has been demonstrated in a production environment and substantial payoffs are indicated in airframe applications.
A Finite Element Model of Orthogonal Metal Cutting
Authors: Strenkowski J. S. , Carroll J. T.
Published: July 2009

A finite element model of orthogonal metal cutting is described. The paper introduces a new chip separation criterion based on the effective plastic strain in the workpiece. Several cutting parameters that are often neglected in simplified metal-cutting models are included, such as elastic-plastic material properties of both the workpiece and tool, friction along the tool rake face, and geometry of the cutting edge and workpiece. The model predicts chip geometry, residual stresses in the workpiece, and tool stresses and forces, without any reliance on empirical metal cutting data. The paper demonstrates that use of a chip separation criterion based on effective plastic strain is essential in predicting chip geometry and residual stresses with the finite element method.
An On-Line Tool Wear Sensor for Straight Turning Operations
Authors: Suzuki H. , Weinmann K. J.
Published: July 2009

This paper describes the design of an on-line tool wear sensor for straight turning operations, which will lead to the realization of adaptive control for optimization (ACO). Tool wear is detected by measuring the change in distance between tool holder and work surface using a stylus which is mounted on the tool holder. The stylus movement is sensed by a displacement transducer. The experimental results indicate that the sensor is capable of measuring tool wear with satisfactory accuracy.
Active Control of a Compliant Wrist in Manufacturing Tasks
Authors: Cutkosky M. R. , Wright P. K.
Published: July 2009

A robotic wrist unit has been constructed and is functioning on a large industrial robot used to load, assemble, and finish parts in an automated metal working cell. The wrist uses force feedback and remote-center-compliance techniques similar to those that have been developed for assembly robots. The wrist employs four spherical hydraulic actuators that behave as adjustable springs with a stiffness that varies between 5.8 × 103 and 7.9 × 103 N/m. This allows the center of compliance to be projected over a range from 25 to 157 mm out from the upper platform of the wrist. The wrist has 5 1/2 degrees-of-freedom, being compliant in each direction except axial extension. Deflections of ± 4.6 mm in the radial plane and 5.1 mm in compression are possible. The accuracy of the sensors over this working range is within 0.025 mm for translations and within 0.001 rad for rotations.
Cutting Process Dynamics Simulation for Machine Tool Structure Design
Authors: Lee S. J. , Kapoor S. G.
Published: July 2009

A methodology to simulate the real cutting process dynamics using a finite element structural model and a mechanistic face milling force model is proposed. While the finite element structural model provides an analytic way to assess structural dynamic characteristics, the mechanistic face milling force model calculates the time histories of cutting forces taking many cutting process parameters into consideration and acts as forcing functions to the structural model. The methodology is verified through experimentation. The effects of structural parameters and cutting process parameters on the dynamic behavior of the machine tool structure are also studied. The results indicate that the proposed methodology can greatly enhance the machine tool design process.
On the Doubly Regenerative Stability of a Grinder: The Theory of Chatter Growth
Authors: Thompson R. A.
Published: July 2009

A mathematical method is devised to solve for the growth of chatter in grinders. The chatter growth rate is important because the grinding process is generally unstable. As such there is a need to find the conditions which minimize wheel and workpiece wave growth and optimize, the time between wheel dressing cycles. The analysis of grinding is complicated by the fact that regenerative feedback from both the wheel and workpiece drive the system. The treatment of this complication follows the author’s past work [1–3], but here, instead of assuming a constant chatter amplitude, the amplitude is allowed to vary according to the law, F = F0eαt, and the objective is to solve for α.
Extensive Analysis and Development of Straightness Measurement by Sequential-Two-Points Method
Authors: Tanaka H. , Sato H.
Published: July 2009

Characteristics of errors which might occur in the straightness measurement method due to sequential-two-points were investigated. The investigation made it clear that the slight discrepancies of alignment at the tip between two displacement sensors would be accumulated onto the portion of linear increment generally observed when the straightness is measured; the method of compensation is analytically shown. It is theoretically proposed that the error which might be introduced by the yaw of the tool post and is neglected by the present system can be evaluated by the measurement using sequential-three-points. It is also shown that the measurement system due to the sequential-two-points works stably even for the case when the work on the lathe is rotated. The cylindricity obtained by the measurement during the work rotation agrees well with that obtained by static measurements.
In-Process Detection of Tool Breakage in Milling
Authors: Lan Ming-Shong , Naerheim Yngve
Published: July 2009

An adaptive signal processing scheme for the cutting force signal was used to detect the fracture and chipping of a cutting tool during milling operation. The cutting force signal was modeled by a discrete autoregressive model where parameters were estimated recursively at each sampling instant using a parameter adaptation algorithm based on a model reference adaptive system approach. The sensitivity of the prediction error and the estimated parameters to the frature and chipping of a cutting tool are presented. The influence of the adaptation algorithm parameters on the estimation results is discussed. The effect of the change in cutting conditions on the estimation results is also investigated.
Further Analysis of Axisymmetric Upsetting
Authors: Carter W. T. , Lee D.
Published: July 2009

Analytical modeling of deformation processing methods requires a thorough understanding of the die–billet interfacial conditions, in particular, the nature of frictional boundary conditions. In order to gain insight into the role of friction on the deformation behavior of metals under uniaxial compression, a series of carefully controlled experiments were made with 6061-T6 aluminum cylinder and ring specimens. From measurements of the change in internal diameter and the height of the ring specimens, the average friction coefficient can be found using the calibration method proposed by Male and Cockcroft. Using this friction coefficient, a series of finite element analyses were made to model the deformation of solid aluminum cylinders which were compressed under identical die–billet contact conditions. An updated Lagrangian formulation and the contact surface algorithm of the ADINA finite element code were used in the analysis. Comparison of the experimental findings with those of the finite element analysis shows some discrepancies; possible causes for these differences are identified.
Measurement of Grinding Temperature Using Infrared Radiation Pyrometer With Optical Fiber
Authors: Ueda T. , Hosokawa A. , Yamamoto A.
Published: July 2009

The heat pulses produced by cutting grains in a workpiece were measured using an infrared radiation pyrometer connected by means of an optical fiber. The results obtained were compared with those from a thermocouple to investigate the effect of differences in response speed on the output. The I.R.P., using an InAs cell as a detector which has a response time in the order of μs, can detect heat pulses with great accuracy and its signal trace versus time has many sharp peaks. The thermocouple formed by spot welding is inferior in response speed, and less accurate in registering heat pulses.