bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional Assessment of the Grinding Wheel Surface Characteristics by Turbulence Amplifier
Authors: Radhakrishnan V. , Rahman J. F.
Published: July 2009

The importance of wheel surface topography and its influence on the grinding performance and the workpiece finish is widely recognized. Wheel surface characterization is an important aspect towards the development of adaptive control and process optimization in grinding. This paper highlights a new method of assessing the characteristics of the wheel surface by measuring air flow around the wheel using a turbulence amplifier system. Different wheel surface profiles have been generated with different dressing feed rates and their effective profiles have been compared with the output values of the turbulence amplifier. An optimum dressing feed rate range for the production of fine surfaces has been suggested. The changes in the wheel topography from freshly dressed to glazed condition, as the grinding proceeds, have been measured and their effect on the ground finish has been discussed. Based on the experimental results, the possible practical utilization of this technique in industry is suggested to ascertain the stage of wheel glazing and loading at which redressing is required for better performance.
The Development and Testing of the Space Shuttle Reaction Control System
Authors: Edwards P. R. , Svenson F. C. , Chandler F. O.
Published: July 2009

The Space Shuttle Reaction Control System design requirements, regimes of operation, and physical characteristics are described to show how they influenced the subsystem design. An overall RCS description and discussion of several components including the thruster, propellant tank, AC propellant isolation valves, and burst disc pressure relief valve assembly are presented. The current status of the Forward Reaction Control System development tests at the NASA-White Sands Test Facility are discussed including test results and unique developments encountered as a part of the test program.
A Deep Drawing Test for Determining the Punch Coefficient of Friction
Authors: Rajagopal S.
Published: July 2009

A deep drawing test is described for measuring the coefficient of friction between the cylindrical surfaces of the punch and the cup wall. The test is based on an analysis of the stress system in the cylindrical region of contact. Experimental data are presented for steel and aluminum blanks deep-drawn into cups under different lubrication conditions, and the advantages and limitations of the method are discussed.
A Method to Measure Contact Pressure Between Metallic Surfaces by Changes in Surface Roughness
Authors: Kato S. , Yamaguchi K. , Kato T.
Published: July 2009

A new method was developed to find the interface pressure distribution of metallic surfaces in contact by measuring the roughness change. The pressure distribution of two kinds of contact surfaces, a sphere and a flat surface, a flat end of a cylinder and a flat surface, was measured experimentally by the method and compared with that of the elasticity theory. As a result, it was shown that it is possible to find the pressure distribution by measuring the roughness change in the contact surface before and after contact.
Optimum Process Design for a Single-Stage Multifunctional Production System
Authors: Hitomi K. , Ohashi K.
Published: July 2009

A mathematical model is constructed for analysis of optimum process design of a multifunctional production system, such as machining centers, under the minimum-time criterion. Proposed computational algorithm consists of determining the optimum sequence of operations and the optimum cutting conditions. A numerical example is given to show the practical applicability of this algorithm.
Dynamic Analysis of Milling Machine by Torque Signals
Authors: Shuaib A. R. H. , Garcia-Gardea E. , Wu S. M.
Published: July 2009

Cutting torque signals of a vertical milling machine are used for the analysis and identification of the machine tool system. The force signals are represented by stochastic differential equations obtained by the dynamic data system (DDS) modeling technique. The parameters of the models are used to identify the dynamic modes of the machine tool system. Changes in the dynamic behavior of the machine tool system with cutting conditions have been observed from the dynamic characteristics of the constituent dynamic modes. Stability of the system has been investigated using the most compliant machine tool system mode characteristics. This suggests an alternative technique for obtaining the stability limits of the system instead of the conventional lengthy chatter tests.
Laboratory Investigation of Wheel Rail Contact Stresses for U.S. Freight Cars
Authors: Kumar S. , Rajkumar B. R.
Published: July 2009

Importance of the wheel rail contact stresses in track degradation and safety of trains is discussed. Theroetical elastic contact stresses based on Hertz theory for various U.S. railroad cars are presented. These contact stresses were produced for simulation of different cars on the IIT-GM-EMD wheel rail simulation facility which is briefly discussed. Experimental measurements of contact areas at the facility for 55, 70, 95 and 125 ton cars, including changes due to the plasticity and wear effects are given. Based on these, the average contact stress variation with time is shown. It is observed that the contact stresses for cars stabilize at a nearly constant value within a range of 88–103 ksi. Due to increased plasticity effects under cyclic loading the stabilized contact stress levels for heavier cars are found to be at lower stress levels as compared to lighter cars. Stabilized contact stresses are compared with theroetical values predicted by Melan and Johnson under simplified load and material behavior conditions. Experimental values are somewhat higher as expected. Laboratory data on contact stresses is compared with contact stresses measured at the Facility for Accelerated Service Testing for 100 ton cars. Good corroboration with laboratory data was observed. A summary comparison of current industry design contact stresses with laboratory and field measurements shows that the contact stresses are too high and not stable for U.S. freight cars using the current AAR standard wheel rail designs. A concept of profile stability is proposed for future profile designs which are much needed for the heavy tonnage cars.
An Investigation of the Mechanics and Noise Associated with Coal Cutting
Authors: Becker R. S. , Anderson G. R. , Kovac J.
Published: July 2009

The results of a laboratory investigation of coal cutting mechanics and noise are presented. These experiments were performed using a linear cutting apparatus that operates over a broad cutting speed range. The influence of several coal cutting parameters on the noise, force, productivity, and specific energy associated with linear cuts was ascertained. Some basic theoretical aspects of coal cutting mechanics and noise generation are discussed, and the results of the laboratory experiments are used to formulate analytical models of the coal cutting forces and noise. The analytical model for coal cutting noise is then generalized to account for the more important effects of rotary cutting. Based on the generalized model, an estimate of the sound pressure level at an operator’s position is made for a typical continuous mining machine. It is concluded that by employing linear rather than rotary cuts, using deeper depths of cut, slower cutting speeds, and more efficient cutting tools, it is possible to reduce the level of coal cutting noise, as well as provide benefits to other important areas of health and safety in underground mining.
Point Admittance of Cylindrical Shells With and Without Ring-Stiffening
Authors: Eichelberger E. C.
Published: July 2009

The dynamical response of two cylindrical shells, one with and one without ring-stiffening, was investigated. Particular attention was placed on the use of ring-stiffening to provide velocity insertion loss at the point of excitation. The driving-point admittance was measured and compared with predictions using the Mean-Value Admittance Method [1]. This method predicts the geometric-mean of the response of a vibrator with respect to frequency, and is valid at low as well as high frequencies. The basic computations involve the mode masses and mode density. The measurements were in good agreement with the theory and demonstrate that the Mean-Value Admittance Method is a practical means of predicting the vibrational response of shell structures to point excitation.
The Reduction of Capstan Effectiveness by Cable Bending Resistance
Authors: Shashaty A. J.
Published: July 2009

The simple exponential capstan equation relating output tension to back tension is valid for most cable applications. However, when the capstan is small and the back tension is low, the bending resistance of the cable reduces its conformity to the capstan, and thereby reduces the effectiveness of the capstan. The conditions under which a cable will not conform to a capstan are worked out. These conditions can be expressed as a minimum back tension required for the capstan to work. Two applications are considered. For a typical coaxial cable on the ship cable machine at a back tension of 5000N (1124 lbf), the effect of bending resistance is negligible. For a different cable on a captain-pair at a back tension of 100N (22.5 lbf), the effect is important. The equations used here are also applicable to other cases where a cable is pulled and bent.
Behavior of Self-Excited Chatter Due to Multiple Regenerative Effect
Authors: Kondo Yoshitaka , Kawano Osamu , Sato Hisayoshi
Published: July 2009

The behavior of self-excited chatter after an excitation is studied by introducing the new idea of a multiple regenerative effect. This considers not only the effect of one turn before, but that of two or more turns before. The analysis explains well some characteristics of the chatter, such as the finite amplitude after the onset, and the generation of chatter marks. Increase of the stability at low cutting speeds is also discussed in terms of a resistive force due to the relative motion between work and tool.
On Some Aspects of Surface Formation in ECM
Authors: Krishnaiah Chetty O. V. , Murthy R. V. G. K. , Radhakrishnan V.
Published: July 2009

The mechanism of surface formation in electrochemical machining (ECM) is not fully understood because of the complex heterogenous reactions possible in the inter-electrode gap. A complete understanding of the flow phenomenon can provide considerable information in this regard. Qualitative and quantitative analyses of surface profiles presented in this paper highlight the significant effect of the flow velocity on surface formation. The flow velocity significantly affects the short wavelength irregularities of the surfaces produced in anodic smoothing. At lower velocities, the workpiece grain size also influences the surface finish. The smaller grains yield better finish when the Reynolds number is below 10,000. The cathode reproduction is poor with increasing velocity but the overall finish is found to be good. Short wavelength irregularities present in the reproduced profiles reduce considerably with increasing flow velocity. Better reproduction is seen when the lay of the tool is across the flow. Such studies are significant in understanding the anodic smoothing and cathode reproduction, and these experimental results augment the theoretical models developed in this field.
Analytical Modeling of Wave Interference Directional Microphones
Authors: Carnes T. N. , Reynolds D. D. , Hixson E. L.
Published: July 2009

Analytical models of a wave interference directional microphone were developed for use on a digital computer. Wave interference directional microphones consist of cylindrical tubes with sound pressure receiving ports spaced along their length. Electro-acoustical transducers are placed near one end. Both ends are terminated by acoustical impedance elements. The microphone is classified as an end-fire receiving array for air use. Variations of this type of microphone have existed for many years; however, a detailed analytical model was never developed and verified. The microphone was modeled using acoustical transmission line theory. The most important effects on performance, tests proved, are caused by internal sound wave propagation, and these effects can alter performance drastically from that predicted by geometric line array theory. The models were verified by comparison of measured and predicted frequency response and directivity of actual microphones.
The Role of Microcracks in Large Plastic Deformation
Authors: Luong L. H. S. , Brown R. H.
Published: July 2009

This paper describes the results obtained from shear-compression tests carried out at low strain rates and at strain rates equivalent to those in a typical machining operation. These tests together with metallographic work are used to explain the influence of microcracks on the flow stress of work material. It is shown that the negative work-hardening effect observed at large strain deformation in the presence of compressive stresses is associated with the behavior of microcracks. A mechanism is proposed to account for this phenomenon.
A Data Dependent Systems Approach to Dynamics of Surface Generation in Turning
Authors: Pandit S. M. , Revach S.
Published: July 2009

A new investigative approach to metal cutting dynamics is proposed based on wavelength decomposition of surface roughness by data dependent systems (DDS). This approach distinguishes from the commonly used Fourier transform analysis. It is shown to be capable of throwing light on both macroscopic and microscopic aspects of cutting mechanics. Workpiece surfaces from turning experiments, changing only speed and only feed, are used to illustrate that the macro-effects of cutting conditions and vibrations can be related to RMS components due to large wavelengths of a few tenths of mm magnitude. In particular, the so-called Spanzipfel effect is accounted for and its RMS is derived. It is also shown that wavelengths of a few micrometer magnitude, estimated from the workpiece surface roughness, seem to provide an independent estimate of chip surface lamellar widths in micro-morphology, well in agreement with earlier investigations.
Twist Moments and Deformations in Submarine Cable Installation
Authors: Shashaty A. J.
Published: July 2009

Submarine cable systems made up of combinations of armorless cable and armored cable are subject to twist moments and deformations during installation. These stresses and strains may damage the cable. An expression is presented for the twist moment and deformation in a string made up of any number of segments, laid with or without bottom tension. Three sample cases are worked out using two specified cables.
Plastic Flow Instability Under Compressive Loading During Shear Spinning Process
Authors: Gur Micha , Tirosh Jehuda
Published: July 2009

The sudden appearance of a material bulge beneath the roller during tube spinning operation (referred to as “plastic instability”) is considered experimentally and examined quantitatively via an upper bound analysis. The phenomenon is explained by a sudden transfer of flow from one admissible mode to its competing mode when an external condition (or few conditions) is changed in a certain way to be discussed (e.g., increasing the roller angle of attack, increasing the initial tube thickness, etc.). As a by-product, the interrelation between the dominant variables of the process emerges. The associated formulation with its inherent idealizations enables one to mark the line between favorable and unfavorable working conditions of the spinning process. Experimental evidence demonstrates the utility of the proposed approach.
Analysis of Extrusion or Drawing of Polygonal Sections Through Straightly Converging Dies
Authors: Gunasekera J. S. , Hoshino S.
Published: July 2009

This paper describes a new method for obtaining optimal die shape which produces minimal stress in the extrusion or the drawing of nonaxisymmetric sections from round bar stock. The surface of the die is generated by an envelope of straight lines drawn from the points on the perimeter at the entry section to the corresponding points at the exit of the die. An upper bound technique based on the kinematically admissible velocity field is used to determine the forming stress for different regular polygonal sections (the number of sides is from three to infinite) for a given reduction of area, material property, and frictional condition. The theoretical results are compared with known experimental and theoretical data and are found to be in good agreement.
Vibration of Wide Band Saw Blades
Authors: Ulsoy A. G. , Mote C. D.
Published: July 2009

The vibration and stability of wide band saw blades is investigated using an axially moving plate model which includes the effect of in-plane stresses upon stiffness. The equation of motion is developed from Hamilton’s principle, and approximate solutions are obtained using both the classical Ritz and finite element-Ritz methods. Experimental results from a large-scale band saw are presented and show good agreement with the results of the approximate analyses. Analytical results are presented which show the contributions of axial velocity, the wheel support system, blade damping, transverse forces, and in-plane stresses to band vibration and stability. The implications of these results for optimizing the band saw design are also indicated.
Drill Point Geometry and Optimization
Authors: Kaldor S. , Lenz E.
Published: July 2009

The geometrical parameters of the drill point, i.e., relief angles, chisel form, web size, and errors of symmetry have a major influence on drill performance. This paper deals with geometrical aspects of the drill point and with the development of fundamental mathematical definitions for the design of improved drill point grinders. A drill point grinder was built and a set of drills was ground and tested to find the optimum clearance angle. When compared with the standard commercial point, the new point with the optimum clearance angle gave an increase in tool life by more than a factor of two.
Development of a 36-Axle Schnabel Rail Car
Authors: Wivagg A. P.
Published: July 2009

The high capacity 36-Axle Schnabel Rail Car recently delivered to Combustion Engineering, Inc. (C-E), is traced from initial inception through delivery. The Schnabel Car carries its load suspended between two halves, which allows delivery of certain oversized and overweight components normally restricted to other modes of transportation. The paper discusses the development of design requirements, specification, procurement, testing, and unique features of the car. It was manufactured by Krupp Industrie und Stahlbau of West Germany and is the largest in the world.
On the Catastrophic Shear Instability in High-Speed Machining of an AISI 4340 Steel
Authors: Komanduri R. , Schroeder T. , Hazra J. , von Turkovich B. F. , Flom D. G.
Published: July 2009

An AISI 4340 Steel (325 BHN) was machined at various speeds up to 2500 m/min (8000 SFPM). Longitudinal midsections of the chips were examined metallurgically to delineate the differences in the chip formation characteristics at various speeds. Chips were found to be continuous at 30 to 60 m/min (100 to 200 SFPM) but discontinuous below this speed. Instabilities in the cutting process, leading to different types of cyclic chip formations, were observed at cutting speeds above 60 m/min (200 SFPM). Fully developed catastrophic shear bands separated by large areas (segments) of relatively less deformed material, similar to that when machining titanium alloys, were observed in the chips at cutting speeds above 275 m/min (800 SFPM). The intense shear bands between the segments appeared to have formed subsequent to the localized intense deformation of the segment in the primary shear zone. As the cutting speed increases, the extent of contact between the segments is found to decrease rapidly. At speeds of 1000 m/min (3200 SFPM) and above, due to rapid intense, localized shear between the segments, these segments were found to separate completely as isolated segments instead of being held intact as a long chip. The speed at which this decohesion occurs was found to depend upon the metallurgical state of the steel machined and its hardness. As in the case of machining titanium alloys, the deformation of the chip as it slides on the tool face, i.e., “secondary shear zone,” appeared to be negligible when machining this AISI 4340 steel at high speed. Based on the metallurgical study of the chip and the similarities of machining this material at high speed and that of titanium alloys at normal speed, a cyclic phenomenon in the primary shear zone is identified as the source of instability responsible for the large-scale heterogeneity and a mechanism of chip formation when machining AISI 4340 steel at high speed is proposed.
Experiments on Adaptive Constrained Control of a CNC Lathe
Authors: Bedini R. , Pinotti P. C.
Published: July 2009

The technological and economic aspects of the on-line optimization of turning operations on lathes equipped with a Computerized Numerical Control (CNC) are discussed. A model of the machining process suitable for developing an Adaptive Constrained Control (ACC) is described. For optimization, a hill-climbing strategy which can be software implemented in the operating system of the CNC is used. Performance of such an ACC is also compared with the more general Adaptive Control Optimization (ACO) System. Machining tests carried out on a CNC lathe fitted with the ACC System are reported and discussed. The practical effectiveness of the ACC so developed and the reduction in machining time are demonstrated with reference to complete working cycles of typical workpieces.
Measurement of Cotton Fiber Tenacity on 1/8 Gage HVI Tapered Bundles
Authors: Taylor R. A.
Published: July 2009

The inherent precision and accuracy of the methods used for measuring the fiber bundles strength of cotton encompass the variability among individual measurements and the confidence with which the measurements can be used to predict the strength of yarn or fabric. A high volume instrument developed for measuring the length characteristics of cotton fiber in tapered fiber beards was used to break the same beard for a measure of fiber strength. A method of breaking fiber bundles at a predetermined distance from the sampling clamp was compared with the conventional method—breaking a predetermined number of fibers. Sources contributing to variability of both measurements were defined, analyzed, and compared to sources of variability in Pressley and Stelometer measurements of the same cotton samples. All methods of measuring bundle strength were evaluated for accuracy as predictors of yarn strength for both open-end and ring-spun yarns. Data agreed closely between two methods tested with the high volume instrument. Data from conventional testers (Pressley and Stelometer), however, were better predictors of yarn strength than either HVI method.
A Data Dependent Systems Strategy of On-Line Tool Wear Sensing
Authors: Pandit S. M. , Kashou S.
Published: July 2009

An indirect method of tool wear sensing and critical wear detection is suggested. It is based on the Data Dependent Systems (DDS) modeling of vibrations from an accelerometer mounted on the tool holder at a safe distance away from the cutting process. The DDS provides an estimate of the tool acceleration component, sensitive to wear alone, at the natural frequency of the tool confirmed by impulse response testing. This acceleration decreases at the beginning, approaches a minimum at the critical wear, and increases again, much the same way as a rate of wear curve. The trend remains unchanged under different cutting conditions, although the actual values change. Based on this finding, an on-line tool wear sensing strategy is proposed, verified by a confirmation experiment and supplemented by a block diagram of microprocessor implementation.
Plastic Bending of Work Hardening Materials
Authors: Dadras P. , Majlessi S. A.
Published: July 2009

The plane strain plastic bending of rigid-work hardening materials has been investigated and two models have been proposed. In Model I, a numerical solution based on a linear σ¯ – ε¯ approximation for fibers in reversed loading has been presented. Model II is an extension of Proksa's analysis to the case of materials described by Ludwik's equation. It has been demonstrated that the results of these models are generally in close agreement. Also, the bending moment and the decrease in plate thickness predicted by these models compare favorably with reported experimental data.
Ring Forming: An Upper Bound Approach. Part 3: Constrained Forging and Deep Drawing Applications
Authors: Avitzur B. , Van Tyne C. J.
Published: July 2009

The generalized ring forming process has been analyzed for a Mises’ material, using an upper bound approach. This analysis allows the motivation for the process to be supplied on any surface and permits the application of external tractions on any other surface of the ring. In this part of the series, application of the general analysis is made to the specific cases of constrained ring forgings and deformation of a flange during deep drawing.
Development of a Friction Element for Metal Forming Analysis
Authors: Webster W. D. , Davis R. L.
Published: July 2009

A three-dimensional finite element friction element has been developed. The friction element has been used in the analysis of round-to-square forward extrusion. Comparison with some limited experimental data is presented.
Variables Governing Patterns of Mechanical Residual Stress in a Machined Surface
Authors: Liu C. R. , Barash M. M.
Published: July 2009

Mechanical residual stress in a machined surface was studied experimentally. Structural change was eliminated by machining low-carbon steel under selected conditions. The shape of the cutting edge was found to govern the residual stress near the machined surface while the length of the shear plane was found to govern the bulk distribution of the stress. It was also found that smaller depth of cut did not always produce lower stresses. The effect of the degree of constraint in the deformation process on residual stress formation was demonstrated by using orthogonal, oblique, and conventional cutting processes. It was observed that a lower degree of constraint in the deformation process produced a lower level of residual stress.
Characteristics, Riemann Invariants, and Plane Strain Plasticity
Authors: Ramalingam S. , Desai P. V. , Kim K.
Published: July 2009

The set of equations governing plane strain plasticity are treated here as a system of homogeneous quasi-linear partial differential equations. Characteristics and Riemann invariants are defined and used. It is shown that when a plane strain plasticity problem is mapped in the plane of invariants (Riemann plane), the domain of plasticity is readily identified and a unique solution is facilitated.
Predicting the Shear Plane Angle in Machining From Workmaterial Strain-Hardening Characteristics
Authors: Wright P. K.
Published: July 2009

An upper-bound type analysis is presented for predicting the “shear plane angle,” φ, in machining, using workmaterial strain-hardening characteristics. The degree of strain-hardening is quantified by referring to standard reference tables for yield strength and ultimate strength. In the model, the first step is to formulate the lowest amount of plastic work needed to cause a shear instability (collapse) in severely strain-hardened material. (In an upper-bound analysis this occurs on a plane at (φ = 45 + α/2.) However, due to work-hardening, this deformation zone geometry is nonunique and the shear plane can “rotate” into the softer material ahead of this initial instability. Using the proposition that the plastic work input remains constant, an equation is then derived which can be used to calculate the degree of shear plane rotation and hence the final position that the shear plane adopts for various workmaterials. In discussion, it is emphasized that this is an introductory analysis which ignores friction at the rake face and the high strain rates and temperatures that arise in practice; however, the agreement between this new, predictive model and experimental data is exceptionally good.
Criterion for the Prevention of Core Fracture During Extrusion of Bimetal Rods
Authors: Avitzur B. , Wu R. , Talbert S. , Chou Y. T.
Published: July 2009

Based on the upper-bound theorem in limit analysis, a theoretical model for core fracture in bimetal rods during extrusion has been developed and a fracture criterion established. The variables affecting core fracture are: reduction in area (r%), die geometry, friction (m), relative size of the core and relative strength of the core. Within the wide range of possible combinations of these process variables, only a small range permits extrusion without fracture. With suitable modifications the present analysis can be extended to develop criteria for sleeve fracture during extrusion and for both core and sleeve fracture during drawing.
An Investigation of the Shell Nosing Process by the Finite-Element Method. Part 1: Nosing at Room Temperature (Cold Nosing)
Authors: Tang Ming-Ching , Kobayashi Shiro
Published: July 2009

The metal-forming process of shell nosing at room temperature was analyzed by the finite-element method. The strain-rate effects on materials properties were included in the analysis. In cold nosing simulations, the nine-node quadrilateral elements with quadratic velocity distribution were used for the workpiece. The treatment of a moving boundary in the analysis of nosing is discussed and successfully implemented in the finite-element program. FEM simulations of 105-mm dia. shells of AISI 1018 steel and aluminum 2024 were performed and solutions were obtained in terms of load-displacement curves, thickness distribution, elongation, and strain distributions. Comparisons with experimental data show very good agreement.
Orthonormal Processing of Metals. Part 1: Concept and Theory
Authors: Suh N. P.
Published: July 2009

Many metal processing techniques are dictated by equilibrium thermodynamics and the kinetics of phase transformation. Consequently, an alloy of a specific chemical composition must be processed in a unique manner to obtain the desired postprocessing microstructure and, therefore, the properties. In this respect conventional processes are coupled; any change in any one process variable and/or the chemical composition affects all the properties of the metal part. This limitation can be eliminated by using orthonormal processing techniques which allow the uncoupling of processing and properties. Examples of Orthonormal Metal Processing (OMP) techniques are given in this paper. A newly developed process comprises the impingement of two or more streams of liquid metal components (which mix due to turbulent eddies) and freezing the liquid mixture rapidly. This process can create a variety of microstructures of various metal compositions. Part 1 of this paper describes the concept and theory. Part 2 presents the experimental results.
Chip Formation With Chamfered Tools
Authors: Hirao M. , Tlusty J. , Sowerby R. , Chandra G.
Published: July 2009

The paper deals with the effect of chamfers on the tool edge on the chip formation process. It is found that both in continuous cutting and in the exit phase of interrupted cutting where chamfers are mostly used the chip formation process is not very different from that obtained with nonchamfered tools. A buildup forms on the chamfer which acts as if it replaces the missing part of the edge. However, the thrust force component increases strongly which should have a beneficial effect on chipping of the tool edge. On the other hand, it will probably worsen flank wear.
A Model for Surface Grinding Based on Abrasive Geometry and Elasticity
Authors: Pandit S. M. , Sathyanarayanan G.
Published: July 2009

A model for a “characteristic grain” consisting of the superimposition of a large and a small wavelength has been introduced. The large wavelength representing the grain has been used in establishing the elastic deflection of the grain. Due to the elastic deflection, the small wavelength representing the cutting edges cuts a smaller “characteristic groove” on the surface, which provides a prediction of the rms value of the ground surface. Specific energy of grinding can also be predicted. The theoretical expressions for the deflection of the grain and for the rms values are developed from this model and found to agree very well with the values obtained by experiments. With an online measurement of the wheel profile, this approach has potential in computer control of grinding.
Development of Anti-Weldability Test in Metal Forming by Means of Strip-Ironing Type Friction Testing Machine
Authors: Kawai N. , Nakamura T. , Dohda K.
Published: July 2009

To develop an anti-weldability test in metal forming, a strip-ironing type friction testing machine was devised to measure simultaneously normal and frictional forces acting on the die during ironing. It can estimate quantitatively the effects of virgin metal surfaces generated during the process and sliding distance on welding. A new method to assess the ability of lubricants to resist welding has been proposed.
Analysis and Characterization of a Pulp Refining System
Authors: Martinez M. R. , Wu S. M.
Published: July 2009

A 12-in. disk refiner was modified and instrumented. The resulting refining system had the capabilities to control the plate gap separation and at the same time monitor the refining or output torque and plate clearance. With a prior knowledge of the refining operation, it was possible to derive an equation which provides a qualitative and quantitative evaluation of the refining process. This equation, called the Optimal Dynamic Equation (ODE), is based on the maximum power that can be transmitted to a packed pulp pad. The calculation of the ODE is accomplished by means of the cross-spectral estimates of the plate clearance and output torque obtained from the Dynamic Data System (DDS) stochastic vector models.
Reference-Word Circular Interpolators for CNC Systems
Authors: Masory O. , Koren Y.
Published: July 2009

Interpolation techniques for CNC manufacturing systems are either of the Reference-Pulse or Reference-Word type. Reference-Pulse interpolators have been discussed in a previous paper [2]. The present paper provides an analysis of a selected number of Reference-Word circular interpolation techniques that are useful in CNC systems. These interpolators function in an on-line iterative mode and generate binary words which are supplied as references to the control loops in Sampled-Data CNC systems. The various methods are evaluated in terms of accuracy, maximum permitted radius, and number of required iterations to complete a circular arc.
Response of Fiber Properties to Gin Machinery and Moisture During Ginning as Measured by HVI
Authors: Anthony W. S.
Published: July 2009

The High Volume Instrument (HVI) classification of cotton provides a detailed characterization of fiber properties that are important to the cotton marketing and manufacturing industries. Several of these properties are influenced by gin machinery; for example, lint cleaners improve the trash grade, grayness, and yellowness of cotton. HVI measurements revealed that moisture content of the cotton during gin processing influenced fiber properties more than did gin machinery. Fiber length, fiber strength, length uniformity, and trash grade decreased as the moisture content during gin processing decreased.
Real Time Identification of Workpiece Material Characteristics From Measurements During Brakeforming
Authors: Stelson K. A.
Published: July 2009

A novel method is described to estimate the material characteristics of a sheet being bent in a pressbrake from punch force-displacement data. The method is simple enough to be used for real time identification of uncertain sheet characteristics. This procedure can be combined with a model of pressbrake bending to provide real time control of the pressbrake. The setup procedure can be eliminated, and the final angle of the bends can be made insensitive to material property variations. A machine controlled in this manner can be integrated into an unmanned flexible sheet metal manufacturing cell.
Computer Simulation of Breathing Systems for Divers
Authors: Sexton P. G. , Nuckols M. L.
Published: July 2009

A powerful new tool for the analysis and design of underwater breathing gas systems is being developed. A versatile computer simulator is described which makes possible the modular “construction” of any conceivable breathing gas system from computer memory-resident components. The analysis of a typical breathing gas system is demonstrated using this simulation technique, and the effects of system modifications on performance of the breathing system are shown. This modeling technique will ultimately serve as the foundation for a proposed breathing system simulator under development by the Navy. The marriage of this computer modeling technique with an interactive graphics system will provide the designer with an efficient, cost-effective tool for the development of new and improved diving systems.
Mechanics of Wobble Broaching. Part 1
Authors: Murty R. L. , Reddy P. Jayapal
Published: July 2009

The kinematics of wobble broaching, a process which can be economically used to produce polygonal holes in single and small lot production, are analyzed. An analysis to calculate the length of contact of the cutter and the workpiece and the area of uncut chip is presented. The analysis indicates that the optimal inclination angle of a wobble broaching head is around 2 deg.
A Multifunction Thermomechanical Analyzer for Fibers—Its Constructional Features and Applications
Authors: Qian Baojun , Tian Hongjiang , Yang Pingyu , Wu Zongquan
Published: July 2009

The construction of an improved model of TMA for fibers is briefly described. Two special features are: use of an electronic balance for measuring force and use of a precision screw driven by a servo-step motor for measuring length. Besides the usual thermomechanical measurements, the use of the instrument as a research tool for a number of purposes like fiber texture, orientation, heat treatment, and so on has been amply illustrated.
A Method for In-Process Failure Prediction in Cold Upset Forging
Authors: Ettouney O. , Hardt D. E.
Published: July 2009

This paper addresses the prediction of plastic tensile instability and ductile fracture of a specimen undergoing a compression test (simple upsetting). The method used to predict failure is based primarily on Thomason’s approach for predicting tensile plastic instability in compression tests. However, to apply this method to in-process prediction, a means for calculating the flow stress-strain properties from in-process measurements is needed. A method is introduced that is derived from Bridgman’s correction factor for effective stress after necking occurs in the tensile test, but with a different approach that is suitable for compression specimens. The new correction factor enables one to correct the effective stress after barreling occurs, which eliminates the need for an ideal test (without barreling) to find the effective stress of a specimen. The results were in agreement with those derived from an ideal compression test. Stress data found using this correction factor was then used to predict failure using Thomason’s method.
Mathematical Model for Multifacet Drills
Authors: Wu S. M. , Shen J. M.
Published: July 2009

Mathematical models are developed for the first time to describe a multifacet drill (MFD) point geometry, which has been evolved by experiments since 1953 in Peking. A precise grinding process has been adopted on a CNC five-axis drill grinder using the model. A highly repetitive MFD has been reproduced to ensure its further development and applications.
Cylindrical Flank Twist Drill Points
Authors: Fugelso M. A.
Published: July 2009

The mathematical models of twist drills usually require the cutting edge of the drill to be straight. This requirement restricts the clearance angle near the chisel edge to undesirably small values. By rotating the drill about its own axis before sharpening 5 to 20 deg the clearance angle distribution versus drill radius can be improved at the relatively small penalty of having a slightly curved cutting edge.
Relative Assessment of the Dynamic Behavior and Cutting Performance of a Bonded and a Cast-Iron Horizontal Milling Machine
Authors: Chang H. C. , Sadek M. M. , Tobias S. A.
Published: July 2009

The dynamic behavior and the cutting performance of a horizontal milling machine, the structure of which was fabricated by bonding, are compared with those of a machine of nominally identical specification but containing cast structural components. Theoretical work predicted the chatter performance of these two machines from vibration tests, using dynamic cutting coefficients characterizing material behavior. The relative performance of the two machines is discussed with the aid of the predicted stability charts, relating to specific cutting conditions, and in a more general form, through merit charts. The stability charts were obtained also by cutting tests, carried out with a helix and a slot cutter. Correspondence between the predicted and measured stability charts was satisfactory. The chatter performance, measured in terms of the maximum stable width of cut, of the bonded machine was substantially better than that of the cast machine for both types of cutters.
The Quantification of Risk in System Design
Authors: Raafat H. M. N.
Published: July 2009

Many manufacturers in the U.K. are becoming more aware of the benefits achieved by safety and reliability studies on new systems and products, particularly those involved in high risk situations or operating in hazardous areas. The basic criteria of merit for plants, systems, and equipment are: safety, economy of operation, and availability. These criteria are interdependent. Safety criteria can be most effective and incorporated easily in the reliability targets if all possible risks were identified and quantified, and system design will then lead to the specification of corresponding quality requirements for components and systems. This paper introduces new extensions to modern safety and reliability techniques for the combination of hardware failures and human errors in the same study for the evaluation of risk in quantitative terms. An assumed design of a semi-automatic boiler control is studied purely for the purpose of this analysis. Shell boilers in the U.K. are designed and operated to a high standard set by the Health and Safety Executive and Engineering Insurance Companies. The example was deliberately simplified to illustrate the methodology, applicability, advantages, and limitations of each reliability technique.
Hydrofilm Extrusion of Tubes Through Optimized Curved Dies
Authors: Cho N. S. , Yang D. Y.
Published: July 2009

An analytical method for hydrofilm extrusion of axisymmetric tubes through optimized curved dies is proposed. The upper-bound method and hydrodynamic lubrication theory are used in combination. The work-hardening effect of metal and the variation of fluid viscosity are taken into consideration. The optimal film thickness and the optimal die profile are found through energy minimization, and also pressure distributions of the fluid are obtained. A new mandrel system is devised for the film formation at the mandrel-billet interface. Experiments were carried out at room temperature for various diameter ratios of the tube, using the axisymmetric curved die. The theoretical prediction of extrusion pressure shows good agreement with experimental measurements for mild steel specimens, using castor oil as the lubricant.
Formability Limits of Relatively Thick Sheet Metal as Determined by the Fukui Conical Cup Test
Authors: Gerdeen J. C. , Daudi A.
Published: July 2009

A plastic stress analysis was made of the conical cup problem using the maximum shear stress criterion. Limiting diameter ratios were determined for both perfect lubrication and friction conditions. A fixture was designed and constructed for 6.0-in. (15.24-cm) diameter blanks up to 0.20 in. (0.508 cm) in thickness. Experiments were conducted with strains determined by the circular grid method.
An Investigation of Grinding and Wheel Loading Using Acoustic Emission
Authors: Dornfeld D. , Cai He Gao
Published: July 2009

This paper investigates the potential for using acoustic emission signal analysis for a monitoring technique for process automation as well as a sensitive tool for investigation of grinding fundamentals. The acoustic emission generated during the grinding process is analyzed to determine its sensitivity to process efficiency and the condition of the grinding wheel. Acoustic emission from surface grinding is used to measure wear-related loading of the grinding wheel and sparkout (or loss of contact) between the wheel and the work surface. A discussion of energy dissipation in grinding and the generation of acoustic emission is included. This investigation showed that the acoustic emission energy, (RMS)2, increases with the combined effects of wheel wear and loading, the signal energy, (RMS)2, is a function of the undeformed chip thickness and that the signal accurately detects work-wheel contact and sparkout with a higher sensitivity than force measurements.
High-Speed Surface Roughness Measurement
Authors: Jansson D. G. , Rourke J. M. , Bell A. C.
Published: July 2009

A prototype apparatus is described that performs a real-time optical measurement of surface roughness in the 2 to 20 microinch AA range, typical of high-quality grinding, honing, and lapping. Ground metal manufactured parts, with surface roughness in the stated range, are illuminated with a 3.39 micron helium-neon laser. The scattering pattern from the surface is scanned across a linear array of lead selenide detectors. Analog and digital electronics control the scanning and measure the intensity incident on each detector. The electronics computes both reflected (specular) and total incident intensity. These two values are used to compute the surface roughness. The system completes a scan and the electronics computes surface roughness in 20 milliseconds. The fast measurement time allows a large area to be scanned. The results demonstrate the feasibility of using the apparatus for online inspection.
New Approaches to the Modal Analysis for Machine Tool Structure
Authors: Wang Shinyi , Sato Hisayoshi , O-Hori Masanori
Published: July 2009

Three new approaches to modal analysis using impulse response were developed to identify the vibration characteristics of machine tool structure. The methods are based on the principle of minimizing the sum of squares of the differences between the measured data and the analytical expression. One of the methods successfully simplified the algorithm of the curve fit procedure and the computation time was significantly economized, so that it could be carried out by a microcomputer with sufficient accuracy for the system having about 30-degrees-of-freedom.
Corner Reproduction Accuracy in Electro-Chemical Drilling (ECD) of Blind Holes
Authors: Jain V. K. , Jain Vinod Kumar , Pandey P. C.
Published: July 2009

Little information is available about the corner shape and size produced in electrochemical drilling of blind holes. On this account prediction of the complete anode shape analytically, in ECD, is not possible. This paper reports the experimental findings regarding the shape and size of the corners copied, in the anode during electrochemical drilling of blind holes using a tool of specified geometry. An equation evolved by regression analysis of experimental data has been suggested for this purpose. With a view to improve results, an equation based on dimensional analysis has also been presented. Finally, a comprehensive mathematical model accounting for the independent, higher order, and the interaction effects of different important process parameters on the yield (anode radius) has been proposed and its adequacy has been tested by the analysis of variance and accuracy against experimental data.