Computer-aided analysis and design of the shape rolling process for producing turbine engine airfoils

Mild steel (AISI 1018) was selected as model cold rolling material and Ti-6A1-4V and Inconel 718 were selected as typical hot rolling and cold rolling alloys, respectively. The flow stress and workability of these alloys were characterized and friction factor at the roll/workpiece interface was determined at their respective working conditions by conducting ring tests. Computer-aided mathematical models for predicting metal flow and stresses, and for simulating the shape rolling process were developed. These models utilized the upper bound and the slab methods of analysis, and were capable of predicting the lateral spread, roll separating force, roll torque, and local stresses, strains and strain rates. This computer-aided design system was also capable of simulating the actual rolling process, and thereby designing the roll pass schedule in rolling of an airfoil or a similar shape

Simulation of bridge die extrusion using the finite element method

This communication reviews previous work on the extrusion of hollow shapes and uses a three-dimensional (FEM) solution to predict load-required, temperature of the extrudate and material flow during the process. A comparison with experiments is made to assess the relative importance of some extrusion parameters in the extrusion process and to ensure that the numerical discretisation yields a realistic simulation of the process. The usefulness and limitations of FEM when modelling complex shapes is also discussed. Methods to assess the difficulty of extrusion of hollow extrusions in general are presented. The paper also illustrates the essentials of numerical analysis to assist the reader in the comprehension of the thermomechanical events occurring during extrusion through bridge dies. Results are presented for velocity distribution in the extrusion chamber, iso-temperature contours and pressure/ displacement traces. These are compared with experiments conducted using a 5 MN press. It is shown that the finite element program predicts the pressure requirement: the pressure/displacement trace showing a double peak which is discussed in some detail. The finite element program appears to predict all the major characteristics of the flow observed macroscopically

A process planning system with feature based neural network search strategy for aluminum extrusion die manufacturing

Aluminum extrusion die manufacturing is a critical task for productive improvement and increasing potential of competition in aluminum extrusion industry. It causes to meet the efficiency not only consistent quality but also time and production cost reduction. Die manufacturing consists first of die design and process planning in order to make a die for extruding the customer's requirement products. The efficiency of die design and process planning are based on the knowledge and experience of die design and die manufacturer experts. This knowledge has been formulated into a computer system called the knowledge-based system. It can be reused to support a new die design and process planning. Such knowledge can be extracted directly from die geometry which is composed of die features. These features are stored in die feature library to be prepared for producing a new die manufacturing. Die geometry is defined according to the characteristics of the profile so we can reuse die features from the previous similar profile design cases. This paper presents the CaseXpert Process Planning System for die manufacturing based on feature based neural network technique. Die manufacturing cases in the case library would be retrieved with searching and learning method by neural network for reusing or revising it to build a die design and process planning when a new case is similar with the previous die manufacturing cases. The results of the system are dies design and machining process. The system has been successfully tested, it has been proved that the system can reduce planning time and respond high consistent plans

Computer numerical controlled (CNC) machining of screws and dies for plasticating extruders : determination of the criteria for implementing CNC machining

The work of this thesis is dedicated to the manufacturing industry making production equipment to manufacture plastic products. The main theme of the thesis is to determine the criteria for implementing Computer Numerical Control machining to make parts with complex geometries for production equipment. A small manufacturing company with job shop type of production was chosen as the subject and study of extruder manufacturing process was performed. The various available alternatives of CNC manufacturing units available in the market were chosen and their feasibility examined. At present a large variety of CNC machine tools are available in the market, offered by manufacturers following different standards. This thesis is organized with the purpose of comparing various technical and economical considerations for CNC machine tool purchase and its application

Optimization of polymer processing: a review (Part I - Extrusion)

Given the global economic and societal importance of the polymer industry, the continuous search for improvements in the various processing techniques is of practical primordial importance. This review evaluates the application of optimization methodologies to the main polymer processing operations. The most important characteristics related to the usage of optimization techniques, such as the nature of the objective function, the type of optimization algorithm, the modelling approach used to evaluate the solutions, and the parameters to optimize, are discussed. The aim is to identify the most important features of an optimization system for polymer processing problems and define the best procedure for each particular practical situation. For this purpose, the state of the art of the optimization methodologies usually employed is first presented, followed by an extensive review of the literature dealing with the major processing techniques, the discussion being completed by considering both the characteristics identified and the available optimization methodologies. This first part of the review focuses on extrusion, namely single and twin-screw extruders, extrusion dies, and calibrators. It is concluded that there is a set of methodologies that can be confidently applied in polymer processing with a very good performance and without the need of demanding computation requirements.This research was funded by NAWA-Narodowa Agencja Wymiany Akademickiej, under grant PPN/ULM/2020/1/00125 and European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No 734205–H2020-MSCA-RISE-2016. The authors also acknowledge the funding by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT (Portuguese Foundation for Science and Technology) under the projects UID-B/05256/2020, UID-P/05256/2020

Incorporating tool deformation in the design of extrusion dies for complex hollow profiles

The potential of OpenFOAM to design extrusion dies, incorporating the Fluid Structure Interaction (FSI)Fundação para a Ciência e a Tecnologia (FCT) - FCOMP-01-0124-FEDER-015126 (Refª. FCT PTDC/EMEMFE/ 113988/2009), FCOMP-01-0124-FEDER-010190 (Refª. FCT PTDC/EME-FME/102729/2008) and PEst-C/CTM/LA0025/2011 (Strategic Project - LA 25 – 2011-2012), SFRH/BD43632/2008, FCT-SFRH/ BPD/ 77467/ 201

Computational rheology with OpenFOAM® computational library

The current capabilities of numerical codes, which able to model very complex processes, and the existing powerful computational resources, clearly promote the employment of numerical modeling tools to assist design-related tasks. The Computational Rheology Group, from the Institute for Polymers and Composites (IPC) of the University of Minho (UMinho), has been developing and exploiting modeling codes for more than one decade, with a special focus on polymer processing applications. During the last 6 years, most of the numerical developments of the Computational Rheology Group were based on the OpenFOAM® computational library. This talk aims at providing an overview of the computational rheology-related work done at IPC/UMinho, in close cooperation with industry, and at illustrating the advantages of using the computational library OpenFOAM ® for the development of new codes. The presentation will cover both the work done by the group to support the design of polymer processing tools and the development of new solvers in the OpenFOAM® computational library

Viscoelastic fluids in profile extrusion: relevance and characterization

Tese de doutoramento em Engineering and Science of Polymers and CompositesA extrusão de perfis termoplásticos é uma técnica de fabrico contínua essencialmente empregue na produção de produtos de seção transversal constante. O projeto de cabeças de extrusão requer uma modelação realista do escoamento que ocorre no seu canal de fluxo e, portanto, necessita de uma caracterização reológica rigorosa do polímero fundido. A presente tese de doutoramento foca-se em dois assuntos, nomeadamente: (i) os efeitos da viscoelasticidade no escoamento confinado que ocorre no canal de fluxo da cabeça de extrusão, e (ii) os efeitos de erros (dimensões das amostras e temperatura) que ocorrem comummente em de testes de reometria extensional uniaxial realizados com a plataforma Sentmanat (SER), com fluidos inelásticos e fluidos viscoelásticos. Os estudos computacionais foram realizados recorrendo à biblioteca computacional OpenFOAM. Relativamente ao primeiro assunto, inicialmente é implementado um sistema de cálculo computacional, e os resultados obtidos com modelos inelástico e viscoelástico são comparados. Para permitir uma comparação adequada dos modelos, primeiramente os comportamentos linear e não linear do material são caracterizados experimentalmente, e os dados obtidos ajustados com um modelo viscoelástico de Giesekus. Em seguida, este modelo é usado para gerar a curva de fluxo (viscosidade de corte versus taxa de corte), e os dados gerados são ajustados, com um código desenvolvido para o efeito, a um modelo inelástico de Bird Carreau. Subsequentemente, os modelos constitutivos viscoelástico e inelástico equivalente são empregues na modelação do escoamento numa cabeça de extrusão de perfil, para aferir o efeito do modelo utilizado na queda de pressão e na distribuição do escoamento previstas. Os resultados obtidos demonstram que a viscoelasticidade desempenha um papel significativo tanto na distribuição do fluxo quanto na queda de pressão, pelo que, idealmente, deveria ser considerada no projeto de cabeças de extrusão de perfil. Relativamente ao segundo assunto estudado, é desenvolvido um modelo computacional que replica os testes de reometria extensional uniaxial efetuados com a plataforma Sentmanat (SER). Numa primeira fase, o trabalho realizado com um modelo inelástico permitiu definir os requisitos computacionais adequados. Esta fase permitiu também concluir que os resultados obtidos com a estratégia de captura de superfície baseada num método Volume-de-Fluido (VOF) geométrico, são melhores que aqueles obtidos com a alternativa algébrica. Tendo em consideração os resultados obtidos com o modelo inelástico, foi desenvolvido um novo código para modelar o escoamento viscoelástico multifásico, usando o método VOF geométrico, para permitir capturar a interface ar-polímero de modo mais preciso. Para além disso, o utilitário do OpenFOAM usado para calcular forças e binários foi adaptado para fluidos viscoelásticos. O sistema computacional desenvolvido é então usado para avaliar o efeito dos erros comuns acima mencionados. Para quantificar o efeito dos erros induzidos, são comparadas as viscosidades extensionais resultantes da modelação numérica com os valores teóricos. Os resultados obtidos mostram que o efeito de erros relativos à temperatura de ensaio é mais significativo do que o correspondente às dimensões da amostra, principalmente quando se utilizam modelos constitutivos viscoelásticos.Thermoplastics profile extrusion is a continuous manufacturing technique that is mostly employed to produce constant cross-section polymeric products. Proper extrusion die design involves realistic modeling of the flow occurring inside the die flow channel and, therefore, accurate polymer melt characterization. The present thesis focuses on two subjects, namely: (i) the effects of viscoelasticity in the confined flow that takes place inside the extrusion die flow channel, and (ii) the effects of common experimental error sources (sample dimensions and test temperature) on the accuracy of the uniaxial extensional rheometry tests performed with the Sentmanat Extensional Rheometer (SER), both for inelastic and viscoelastic fluid models. The computational studies were carried out with the OpenFOAM computational library. Concerning the first subject, a computational framework is developed, and the results obtained from the inelastic and viscoelastic fluids model are compared. To allow a proper model comparison, first, the material linear and nonlinear behavior are characterized experimentally, and the collected data is fitted with the Giseskus viscoelastic model. Afterwards, the fitted Giesekus model is used to generate the material flow curve (shear viscosity versus shear rate), and the data is fitted, with an in-house code, to a Bird Carreau (inelastic) model. Subsequently, the viscoelastic and corresponding inelastic models are employed in a computational study, aiming at comparing the effect of viscoelasticity on the calculated pressure drop and flow distribution. The results obtained demonstrate that viscoelasticity plays a relevant role in both the flow distribution and pressure drop obtained, and, consequently, it should be taken into account when designing profile extrusion dies. Regarding the second subject, a computational setup is devised to model uniaxial extensional rheometry tests performed with the SER device. The work carried out initially with an inelastic model allowed defining of the appropriate computational setup requirements (the computational domain geometry, mesh refinement level, and initial and boundary conditions). This part of the study allowed concluding that the results obtained from a surface-capturing approach based on the geometric Volume-of-Fluid (VOF) method were better than the ones provided with the algebraic counterpart. Having in mind the results obtained with the inelastic model, a new multiphase viscoelastic flow solver was implemented using the geometric VOF, to allow capturing a sharper polymer-air interface. Also, the OpenFOAM utility devised to calculate forces and torques, was adapted to viscoelastic fluids models. The computational framework was then used to assess the effect of the common errors mentioned above. To quantify the effect of the induced errors, the extensional viscosities resulting from the numerical computational studies and the ones achieved with the theoretical counterpart were compared. The results obtained show that the effect of the test temperature errors is more significant than the one corresponding to the sample dimensions, especially when viscoelastic constitutive models are employed.I gratefully acknowlagde funding FEDER funds through the COMPETE 2020 Program and National Funds through FCT - Portuguese Foundation for Science and Technology under the projects UIDB/05256/2020/, UIDP/05256/2020, CPCA/A2/6202/2020, CPCA_A2_6231_2020, NORTE-08- 5369-FSE-000034, under program IMPULSE – Polímeros e Compósitos: Drivers da Inovação Tecnológica e da Competitividade Industrial. I also acknowledge the support of the computational clusters Search-ON2 (NORTE-07-0162-FEDER- 000086) and Minho Advanced Computing Center (MACC)

A Hybrid Intelligent System for Stamping Process Planning in Progressive Die Design

This paper presents an intelligent, hybrid system for stamping process planning in progressive die design. The system combines the flexibility of blackboard architecture with case-based reasoning. The hybrid system has the advantage that it can use past knowledge and experience for case-based reasoning when it exists, and other reasoning approaches when it doesn’t exist. A prototype system has been implemented in CLIPS and interfaced with Solid Edge CAD system. An example is included to demonstrate the approach.Singapore-MIT Alliance (SMA

Mechanical design automation: a case study on plastic extrusion die tooling

The Skills Gap in Mechanical Engineering (ME) Design has been widening with the increasing number of baby boomers retiring (Silver Tsunami) and the lack of a new generation to acquire, practice and perfect their knowledge base. This growing problem has been addressed with several initiatives focused on attracting and retaining young talent; however, these types of initiatives may not be timely for this new group to be trained by an established Subject Matter Expert (SME) group. Automated Engineering Design provides a potential pathway to address not only the Skills Gap but also the transfer of information from SMEs to a new generation of engineers. Automation has been at the heart of the Advanced Manufacturing Industry, and has been successful at accomplishing repetitive tasks with processes, software and equipment. The next stage in Advanced Manufacturing is further integrating Machine Learning techniques (Artificial Intelligence (AI)) in order to mimic human decision making. These initiatives are clear for the type of mechanized systems and repetitive processes present in the manufacturing world, but the question remains if they can be effectively applied to the decision heavy area of ME Design. A collaboration with an industry partner New Jersey Precision Technologies (NJPT) was established in order to address this question. This thesis presents an ME Design Automation process involving a multi-stage approach: Design Definition, Task Differentiation, Workflow Generation and Expert System Development. This process was executed on plastic extrusion tooling design. A Computer Aided Design (CAD) based Expert System was developed for the Automation of design, and the generation of a database towards future Machine Learning work. This system was run on 6 extrusion product examples previously designed by NJPT through traditional methods. The time needed to generate the design was reduced by 95-98%. This thesis demonstrates the capability of automating ME design, the potential impact in industry and next steps towards the application of AI