Automated design of multi-stage forging sequences for die forging

Forgings are produced in several process steps, the so-called forging sequence. The design of efficient forging sequences is a very complex and iterative development process. In order to automate this process and to reduce the development time, a method is presented here, which automatically generates multi-stage forging sequences for different forging geometries on the basis of the component geometry (STL file). The method was developed for closed die forging. The individual modules of this forging sequence design method (FSD method) as well as the functioning of the algorithm for the generation of the intermediate forms are presented. The method is applied to different forgings with different geometrical characteristics. The generated forging sequences are checked with FE simulations for the quality criteria form filling and freedom from folds. The simulation results show that the developed FSD method provides good approximate solutions for an initial design of forging sequences for closed die forging in a short time

Advances in Plastic Forming of Metals

The forming of metals through plastic deformation comprises a family of methods that produce components through the re-shaping of input stock, oftentimes with little waste. Therefore, forming is one of the most efficient and economical manufacturing process families available. A myriad of forming processes exist in this family. In conjunction with their countless existing successful applications and their relatively low energy requirements, these processes are an indispensable part of our future. However, despite the vast accumulated know-how, research challenges remain, be they related to the forming of new materials (e.g., for light-weight transportation applications), pushing the boundaries of what is doable, reducing the intermediate steps and/or scrap, or further enhancing the environmental friendliness. The purpose of this book is to collect expert views and contributions on the current state-of-the-art of plastic forming, thus highlighting contemporary challenges and offering ideas and solutions

Multi-scale Computational Techniques For Design Of Polycrystalline Materials

Your submission was rejected by Pattie Place:I am rejecting because on page 95 there is too much white space. But Page 95 is at the end of a chapter?Microstructures play an important role in controlling distribution of properties in engineering materials. It is possible to develop components with tailored distribution of properties such as strength and stiffness by controlling microstructure evolution during the manufacturing process. When forming metallic components by imposing large deformations, mechanisms such as slip and lattice rotation drive formation of texture in the underlying polycrystalline microstructure. Such microstructural changes affect the final distribution of material properties in the component. By carefully designing the imposed deformation, one could potentially tailor the microstructure and obtain desired property distributions. This thesis focuses on development of novel computational strategies for designing deformation processes to realize materials with desired properties. The techniques presented are an interplay of several new tools developed recently, such as reduced order modeling, graphical cross-plots, statistical learning, microstructure homogenization and multi-scale sensitivity analysis. The primary outcomes of this thesis are listed below: 1. Development of reduced-order representations and graphical methodologies for representing process-property-texture relationships. 2. Development of adaptive reduced-order optimization techniques for identification of processing paths that lead to desirable microstructure-sensitive properties. 3. Development of homogenization techniques for predicting microstructure evolution in large deformation processes. 4. Development of multi-scale sensitivity analysis of poly-crystalline material deformation for optimizing microstructure-sensitive properties during industrial forming processes. The framework for design of polycrystalline microstructures leads to increased product yield in industrial forming processes and simultaneously allows control distribution of properties such as stiffness and strength in forged products. Multi-scale design problems leading to billions of unknowns have been solved using parallel computing techniques. The computational framework can be readily used for selecting optimal processing paths for achieving desired properties. The methodology developed is a fundamental effort at providing detailed deformation process design solutions needed for controlling properties of performance-critical hardware components in automotive, structural and aerospace applications

Metal flow simulation and design of dies for closed die forging

The application of computei aided design and computer aided manufacturing (CAD/CAM) technique to forming is gaining populanty as the lesulting productivity improvements are becoming more and moie appatent. Most users are using CAD/CAM and finite element packages as stand alone packages, where the integiation among these packages in most cases is difficult due to the diffeiences in the layout format of each one. Finite element packages usually have then own pie- and post piocessors, however it is unlikely to include the facilities available in a CAD system such as zooming, pan, layer. This thesis describes a PC-based intei active CAD system foi closed die forging design. This system includes the facilities foi drawing the die geometry, simulation of the deformation process and die analysis undei forming condition. First of all, a commeicial CAD system has been customized to accommodate the empirical guidelines foi closed die foiging design Then a Finite Element program FE has been developed based on the ngid plastic/viscoplastic formulation to simulate the metal flow. A mesh geneiation piogiam has been developed as pait of this system. The CAD system has been used as pie- and post piocessoi foi the mesh generation and the FE programs. To overcome the pioblems encounteied in forming piocesses, such as large deformation and displacements which cause ceitain computational pioblems, a lezoning algorithm has been developed. An elastic/plastic FE piogiam has been used foi die analysis, the FE simulation results of the forming process are used to find out whethei the analyzed die would sustain the forging load or not. This metal flow simulation and die design piocess has been applied to two closed die forging examples, one in plane-stiam condition and the othei in axisymmetric condition. The results were encomaging and in close agieement with the experiments

Cold Micro Metal Forming

This open access book contains the research report of the Collaborative Research Center “Micro Cold Forming” (SFB 747) of the University of Bremen, Germany. The topical research focus lies on new methods and processes for a mastered mass production of micro parts which are smaller than 1mm (by forming in batch size higher than one million). The target audience primarily comprises research experts and practitioners in production engineering, but the book may also be of interest to graduate students alike

NASA Tech Briefs, March 1995

This issue contains articles with a special focus on Computer-Aided design and engineering amd a research report on the Ames Research Center. Other subjects in this issue are: Electronic Components and Circuits, Electronic Systems, Physical Sciences, Materials, Computer Programs, Mechanics, Machinery, Manufacturing/Fabrication, Mathematics and Information Sciences and Life Science

Fundamental study of central crack mechanism and criterion in cross wedge rolling

Cross wedge rolling (CWR), a novel metal forming process for manufacturing axisymmetric stepped shafts, is widely applied in transport industries. Central crack, the cavity formed in the product centre, is a critical problem, preventing its development in safety-critical industries. However, the understanding of the central crack mechanism is insufficient, and there is not yet a robust fracture criterion to predict its occurrence. This study aims to establish a fundamental understanding of the central crack mechanism and build a robust physically-based fracture criterion. An innovative CWR physical model with plasticine billets was built in house, which allowed the dies to be rapidly 3D printed and the workpiece with specific mechanical properties to be efficiently manufactured. The effects of the stress variables and initial material properties (ductility) on central cracking were investigated by varying the die geometries and billet material compositions, respectively. It is found that the maximum shear stress plays a dominant role in the central crack formation, and with the increase of the material ductility, the central crack transitions from brittle fracture to ductile fracture. A robust physically-based damage model set was proposed, along with a novel material constant calibration method. The reliability of the proposed model was validated quantitively by 60 groups of CWR tests with different materials and die geometries. The proposed calibration method will significantly benefit the industry due to the extremely simplified die geometries. To further understand the central crack mechanism in the practical industry, the microstructural characteristics (e.g., inclusion, grain size and phase composition) of two high-strength steel CWR billets (with/without high possibility to crack) were quantitatively analysed and compared. It is found that central cracking can be effectively avoided by controlling the inclusion content in the CWR billets.Open Acces

Friction Force Microscopy of Deep Drawing Made Surfaces

Aim of this paper is to contribute to micro-tribology understanding and friction in micro-scale interpretation in case of metal beverage production, particularly the deep drawing process of cans. In order to bridging the gap between engineering and trial-and-error principles, an experimental AFM-based micro-tribological approach is adopted. For that purpose, the can’s surfaces are imaged with atomic force microscopy (AFM) and the frictional force signal is measured with frictional force microscopy (FFM). In both techniques, the sample surface is scanned with a stylus attached to a cantilever. Vertical motion of the cantilever is recorded in AFM and horizontal motion is recorded in FFM. The presented work evaluates friction over a micro-scale on various samples gathered from cylindrical, bottom and round parts of cans, made of same the material but with different deep drawing process parameters. The main idea is to link the experimental observation with the manufacturing process. Results presented here can advance the knowledge in order to comprehend the tribological phenomena at the contact scales, too small for conventional tribology