Puneet Tandon

Three dimensional modeling and finite element simulation of a generic end mill

The geometry of cutting flutes and the surfaces of end mills is one of the crucial parameters affecting the quality of the machining in the case of end milling. These are usually represented by two-dimensional models. This paper describes in detail the methodology to model the geometry of a flat end mill in terms of three-dimensional parameters. The geometric definition of the end mill is developed in terms of surface patches; flutes as helicoidal surfaces, the shank as a surface of revolution and the blending surfaces as bicubic Bezier and biparametric sweep surfaces. The proposed model defines the end mill in terms of three-dimensional rotational angles rather than the conventional two dimensional angles. To validate the methodology, the flat end milling cutter is directly rendered in OpenGL environment in terms of three-dimensional parameters. Further, an interface is developed that directly pulls the proposed three-dimensional model defined with the help of parametric equations into a commercial CAD modeling environment. This facilitates a wide range of downstream technological applications. The modeled tool is used for finite element simulations to study the cutting flutes under static and transient dynamic load conditions. The results of stress distribution (von mises stress), translational displacement and deformation are presented for static and transient dynamic analysis for the end mill cutter flute and its body. The method described in this paper offers a simple and intuitive way of generating high-quality end mill models for use in machining process simulations. It can be easily extended to generate other tools without relying on analytical or numerical formulations.

Geometric Modeling of Fluted Cutters

Geometries of cutting tools are usually represented by two-dimensional models. This paper outlines the construction of detailed computer aided design models for a variety of fluted cutters that includes slab mills, end mills, and drills; and establishes a new three-dimensional definition for the geometry of fluted cutters in terms of biparametric surface patches. This work presents unified models of both plain and helical slab mills, end mills (with different end geometries), and drills (with a variety of point styles). The surfaces meant for cutting operations, known as flutes, are modeled as helicoidal surfaces. To model the flutes, sectional geometry of tip-to-tip profile is developed and then it is swept according to a sweeping rule, determined by the type of the cutter under consideration. The slab mill consists of flutes and two planar end surfaces, while the end mills and drills have shanks and end geometries also (in addition to the flutes). The geometric models of shank and end geometries are separately developed. The transitional surfaces of these cutters are modeled as bicubic Bezier surfaces or biparametric sweep surfaces. The proposed models employ a novel nomenclature that defines the form of cutting tools in terms of three-dimensional rotational angles. The relations required to map the proposed three-dimensional angles to conventional angles (forward mapping) and their reverse relations (inverse mapping) are also developed for all three types of fluted cutters. The new paradigm offers immense technological advantages in terms of numerous downstream applications.

A Parametric Voxel Oriented CAD Paradigm to Produce Forming Components for Stretch Formed Jewelry

This paper proposes a unique kind of jewelry, called stretch formed jewelry. The paper presents a parametric voxel oriented approach to produce stretch forming components that are dies and punches having different patterns of designs. Stretch formed jewelry is created on thin sheet metals (gold or silver) on top of which design patterns are embossed with die and punch tools by stretching the sheet metal beyond elastic limit. Voxels are predefined small structural elements for which the user defines the key parameters. Parametric voxels can be varied during the design process and are joined together to create the design model by the use of rules. Computer-Aided Design (CAD) in conjunction with Rapid Prototyping (RP) machine generates forming tool components.

Hilbert Curve Based Toolpath for FDM Process

Fused Deposition Modelling (FDM) is one of the most widespread additive manufacturing technique used for fabricating 3D objects without any design constraints. It is a solid-based process in which polymers material in the form of semi molten state is extruded from the nozzle to fabricate the 3D objects. In the present work, a new tool path strategy for FDM process has been developed based on Hilbert curve. Hilbert curve is a space filling fractal curve and its hausdorff dimension is two. This curve is surjective and continuous in nature. The proposed tool path from developed program are validated though simulation and experimental results. The new approach has been simulated using MATLAB computing platform. Boolean operators like intersection and subtraction are utilized for finding the intersection points for the tool path generation. A self-developed extruder system based on screw extrusion is used for the real time application of the algorithm developed. The extruder head is reconfigured to an existing CNC milling machine for printing and production purpose. Case study for different types of prototypes are also presented to demonstrate the capabilities of developed tool path algorithm.

Heterogeneous object modeling with material convolution surfaces

The possibility to attain diverse applications from heterogeneous objects calls for a generic and systematic modeling approach for design, analysis and rapid manufacturing of heterogeneous objects. The available heterogeneous object modeling techniques model simple material-distributions only and just a few of them are capable of modeling heterogeneous objects with complex geometries. Even these approaches have also, at time, shown some glitches while modeling complex objects with compound and irregular material variations. This paper unfolds the development of a stand-alone convolution surface-based modeling approach to model complex heterogeneous objects with multi-functional heterogeneities, entailing stratified sub-analytic boundary-representation, convolution material primitives, membership functions and material-potential functions. One-dimensional (associative and non-associative) and compound two-and three-dimensional material-distribution schemas are formulated and outlined to model simple, compound and irregular material-distributions in simple/complex geometry objects. The paper also illustrates a few examples of modeling complex heterogeneous objects by implementing the approach using specialized languages and software tools. A material convolution surface-based approach is presented for modeling complex heterogeneous objects.Complex one-dimensional material-distributions are modeled with material primitives and field functions.Schema for compound and irregular heterogeneities in two-and three-dimensions is formulated and outlined.We report a few examples of complex heterogeneous object modeling for the validation of proposed approach.

Design and simulation of an intelligent bicycle transmission system

An intelligent bicycle transmission system provides a solution that enables a bicycle rider to keep pedaling in his comfort speed range regardless of the torque or the speed requirement. The cadence or the pedaling speed has a preferred range for every rider. However, a rider can exceed or fall below his preferred range when in need of a torque or a velocity more than what the cycle offers to him. The designed transmission system presented in the paper senses the requisites of the rider, and hence, changes gears automatically so that cyclist can keep pedaling in his preferred cadence range. This paper proposes an extremely cost effective and novel solution that improves upon the existing designs of automatic gear shifting arrangement in bicycles. It incorporates special built-in sensors, electronic control unit and specially designed state-of-the-art actuator mechanism that augment the derailleur mechanism. It keeps the cost of the transmission system within an acceptable range with an uncompromised accuracy. In designing the solution, the preferred cadence range of a given user shall be employed.

Slice Generation and Data Retrieval Algorithm for Rapid Manufacturing of Heterogeneous Objects

With the development of Rapid manufacturing techniques, a heterogeneous object can be manufactured by processing geometric and material information in each layer while slicing the object. The functionality and surface finish of heterogeneous object depends upon precise slicing and accurate information processing i.e. geometric and material during fabrication. The current work focuses on both the issues. Layer thickness is varied using adaptive thickness method. Horizontal and vertical contours are approximated to reduce the error and minimize the effect of geometry and material stair-step effects. Reference based boundary mesh generation approach is used for defining material composition at each point in the slice domain. An algorithm is proposed for scanning layers to retrieve geometric and material information at each point in the object domain. A database system is developed for faster processing of information and to avoid the data redundancy during operation. Reference based approach, proposed algori...

MEDISCRIPT- MOBILE CLOUD COLLABRATIVE SPEECH RECOGNITION FRAMEWORK

This work presents a CAD paradigm to produce traditional zillij style of geometrical patterns using ubiquitous polygonal technique. This method makes use of a grid generated from diagonals of n-sided regular polygon. The grids are in the form of a mesh of having large number of irregular polygons. The vertex of any irregular polygon in the grid is viewed as the point of intersection of two diagonals. These irregular polygons, when located in radial symmetry, generate a zillij style of pattern. The design possibilities increase by increasing the diagonals elements and endless variations of patterns on an isometric grid can be created. These geometrical patterns are ideally suited to computer-controlled manufacturing, so can be executed on a flat wooden surface to produce carvings.Speech recognition is a vital part in medical transciription. The existing speech recognition systems, that run as standalone desktop applications, fall short in many cases due to low accuracy rates and high processing time. The bottleneck in these systems, is the lack of computation power (in terms of processing power and memory) made accessible to them. This paper proposes a mobile-cloud collaborative approach for the automation of speech to text conversion. The model proposed leverages the power of cloud computing and the ubiquitous nature of mobile computing. Computing resthisces can be scaled up/down in the cloud (Elastic Computing) depending on the usage of the system. This kind of speech recognition framework has many real time applications such as IVR systems, Medical Transcription systems, Railway Enquiries, Jthisnalism, Interactive User Interfaces, etc. A generic framework is advantageous, because the speech models in the Automatic Speech Recognizer (ASR) could be trained according to the specific domain required, allowing wide usability. The proposed speech framework is used for medical transcription process. Medical transcription process involves a medical transcriptionist who listens to the recorded speech of a doctor and manually types a transcript file. This process is automated by using the proposed speech framework. With this system, the work of the medical transcriptionist is reduced to error checking in the auto generated transcript file. The entire model is developed for a mobile cloud environment considering the characteristics of cloud delivery models.

A Jewelry Modeler for the Fret-worked Bangles

A parametric feature based jewelry modeler for designing and manufacturing of the Fret-worked bangles. These bangles are made from gold and adorned with fretwork designs. Fretwork is a decorative design that is either carved in low relief on a solid background, or cut out to adorn a jewelry item. Fretwork designs are viewed as features that are to be recurrently removed from the stock-solid bangles. The jewelry modeler supports diverse integrated manufacturing through computer controlled manufacturing. Fret-worked bangles are fabricated using rapid prototyping technique.

Shell Element Formulation Based Finite Element Modeling, Analysis and Experimental Validation of Incremental Sheet Forming Process

This paper presents the effect of shell element formulations on the response parameters of incremental sheet metal forming process. In this work, computational time, profile prediction and thickness distribution are investigated by both finite element analysis and experimentally. The experimental results show that the thickness distribution is in good agreement with the results obtained with Belytschko-Tsay (BT) and Improved Flanagan-Belytschko (IFB) shell element formulations. These two shell element formulations do trade-off between computational time and accuracy. For more accurate results, the BT shell element formulation is better and for less computational time with good results, the IFB shell element is preferable. Finally, BT shell element formulation has been chosen for FE Analysis of ISF process in HyperWorks, since the results of thickness distribution and profile prediction is in better agreement with the experimental results as well as the computational time is less among the shell elements.Copyright