Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xxii, 185 p.; also includes graphics (some col.). Includes bibliographical references (p. 178-185).

Thesis (M.S.)--Ohio University, August, 2004. / Includes bibliographical references (p. 101-104).

Thesis (M.S.)--Ohio University, August, 2004. / Title from PDF t.p. Includes bibliographical references (p. 101-104)

O presente trabalho, apresenta resultados da investigação experimental e da análise computacional acerca do método de ensaio de anéis de aço para obtenção do valor do coeficiente de atrito, existente na região de contato entre as matrizes e os corpos de prova. Buscando atingir os objetivos, foi feito um planejamento do experimento, através do programa MINITAB (2000), levando-se em consideração as variáveis do processo para forjamento a quente de peças para indústria automotiva, os experimentos foram realizados nos laboratórios da Universidade Federal do Rio Grande do Sul (UFRGS). A simulação do ensaio de anel permitiu uma boa estimativa da redução de diâmetros dos mesmos, bem como, do fluxo de material no interior dos anéis e da superfície neutra. A análise estatística dos resultados mostrou que a variável mais importante a afetar o coeficiente de atrito foi a temperatura, seguindo-se do tipo de revestimento das ferramentas, velocidade e material. Para um estudo mais pormenorizado do efeito do material a ser forjado, do recobrimento das ferramentas e da rugosidade das mesmas no coeficiente de atrito será necessário um maior número de repetições dos experimentos. / The present work introduces the result of the experimental investigation and computing analyses regarding the method of trial with steel rings as to obtain the value of friction coefficient, which exist in the contact area between the tools and test bodies. Aiming to reach the objectives, a design of experiments was established through the program MINITAB (2000) taking into account the process variables in order to hot forge parts for the automotive industry, being such experiments accomplished at the laboratories of the Universidade do Rio Grande do Sul (UFRGS). The simulation trial of the ring allowed for good estimate of its diameters reduction as well as internal material flow in the rings and in the neutral surface. The static analyses of the results demonstrated that the most important isolated variable to affect the friction coefficient was temperature, followed by the type of tools covering, velocity and material. However a bigger number of experiments repetitions will be necessary in order to reach a more detailed study about the effect of the material to be forged, of tools covering and roughness in the friction coefficient as well.

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Forging operations are widely used for manufacturing processes. Forging process is done hot, warm or cold. All three temperature ranges have advantages and disadvantages. The aim of this study is to combine the advantages of hot and cold forging in a flange forming process with cylindirical workpieces in a single step. The process idea is the partial heating of the workpiece at locations where large deformations occur and to keep the parts of the workpiece cold at regions where high precision forming is required. Firstly, the process idea has been investigated virtually by the finite element method supplying the theoretical verification of the feasibility of the novel process. By this analysis also the process limits have been estimated. All analysis are based on an elastoplastic large strain material law with thermomechanical coupling. The experimental part of the study served to realize the new process idea and to verify the process window. In the experimental study two different materials, three different part geometries and different initial conditions such as temperature field, lubrication etc. have been investigated. The specifimens are heated by induction.

As metals have high formability at elevated temperatures, hot forming is preferred and widely used in manufacturing of complicated geometries. The term hot forming is usually used if the whole workpiece is processed at elevated temperatures. However, for certain products high formability is required only locally. Forming by local heating is proposed to provide ease of manufacturing of local forms on the workpiece. Also, tools can be simplified by this method. In this study, local laser heating procedures are applied to obtain local forms on cylindrical bulk metal products in a single step. Locally heated workpieces are formed between two flat dies. Both solid and hollow products have been investigated experimentally and by finite element modeling. The experimental studies and finite element analyses are done simultaneously in order to obtain optimum local deformation characteristics. Three different materials together with different initial geometries and various local laser-heating procedures are applied to search for the process window. The limits of applicability are determined and examples of application are supplied.

Roll-forging is a metal forming process and mainly used for preform forging of long parts prior to press or hammer forging in the industry. Variable cross sections through the length of billet can be obtained by roll-forging to acquire an adequate distribution of material to the next forging stages. In the design of process and dies used in roll-forging, there are some empirical techniques in literature. However these techniques only provide approximate reduction ratio and elongation during the process and the geometry of the workpiece at the end of each stage cannot be determined exactly by using these techniques. In this study, multistage roll-forging process has been analyzed by using a finite element analysis software to examine material flow, temperature, stress and strain distribution at each roll-forging step. The geometries at the intermediate stages have been determined. Computer results have been compared to experimental results and good agreement has been observed.

The diploma thesis deals with the technology of production of the body of an artillery shell caliber 155 mm from C60 steel. The part is manufactured in series of 100,000 pieces. Based on a literature study and materials, a technological procedure of drop forging was designed, taking into account the specific shape of the forging. The volume of the starting blank and the forming force were determined. A suitable forming machine was selected based on the magnitude of the forming force. The design of tools for punching operations and reduction diameters of sets of rollers for forging stretching was also performed. In the technical and economic evaluation, the material costs for the production of the entire series were quantified.

The project elaborated in frame of engineering studies branch 2307. The project is submitting design of technology production of holder by solid forming of steel 12 020.0. Pursuant to of the literary pursuit a problem of die forging and calculation was designed forging on a vertical cranked press LMZ 1600 and with nominal forging force 16MN (producer ŠMERAL Brno). The lower ejector is using for extrusion component.Heating billet is accomplished by using induction furnance type SOP 400kW.For trimming is used trimmning press LKOA 200 with force 2 MN. For holding of dies is used holder QLZK 1600/UC, dies are made of instrumental steel 19 552.9. A part of this project is economic estimation of production and produce of manufacturing drawings.