Simulation of the stress-strain state of a tubular billet during the expansion of its middle part using rigid die

В работе представлены результаты моделирования в конечно-элементном программном комплексе ANSYS напряженно-деформированного состояния тонкостенной трубчатой заготовки из титанового сплава ОТ4 в процессе раздачи эластичной средой по жесткой матрице. Рассматривается осесимметричная матрица в виде тела вращения с криволинейной образующей. Задача решается в осесимметричной квазистационарной постановке. Конечно-элементная модель включает пуансон, матрицу, трубчатую заготовку, и эластичное рабочее тело. Пуансон перемещается в вертикальном направлении вниз, передавая усилие на деформируемую деталь через рабочее тело. Фрикционное взаимодействие происходит по закону Кулона. Проведен анализ напряженно-деформированного состояния детали в процессе формообразования. Исследовано распределение остаточных напряжений, упругое пружинение после снятия нагрузки и утонение стенок детали. Показана возможность получения детали типа «переходник» из титанового сплава ОТ4 холодным пластическим деформированием без нагрева заготовки. In this paper, the results of simulation of the stress-strain state of a thin-walled tubular blank made from titanium alloy OT4 in the ANSYS finite element software package in the process of expansion by an elastic medium in the rigid die are presented. The axisymmetric die in the form of a body of revolution with a curvilinear generatrix is considered. The problem is solved in an axisymmetric quasi-stationary setting. The finite element model includes a punch, a die, a tubular blank, and an elastic working body. The punch moves vertically downward, transmitting the force to the deformed tube through the working body. Frictional interaction occurs according to the Coulomb's law. The analysis of the stress-strain state of the deformed detail in the process of shaping is carried out. Distribution of residual stresses, elastic spring back after removal of the load and wall thinning of the detail are investigated. The possibility of obtaining the "adapter" type detail from titanium alloy OT4 by cold plastic deformation without heating the blank is shown.

Grinding and buffing of work surfaces in crankshafts and cams of camshafts by endless diamond belt

A technology and a tool for processing work surfaces in crankshafts and cams of camshafts by endless diamond belts are considered. The characteristics of endless diamond belts and their potentialities in assurance of roughness and efficiency at work surface grinding and polishing are shown. The purposefulness in assurance of an optimum curvilinear transverse section of cams in camshafts by grinding with endless belts is defined. It is shown, that it is possible to control a curvilinear profile of cams in camshafts at the expense of a belt width and a belt tension. It is based on a theoretical basis of the interaction of a rigid die (cam) with the elastic half-space (belt). An optimum curvilinearity of the transverse section of a cam ensures the increase of its life.

Directional Thickness Alteration of a Thin-Walled Ring Blank Using Flanging and Forming for the Purpose of Receiving Conical Part

In this article the flanging method of thin-walled ring blanks using the elastic punch and rigid die scheme is investigated. Presence of a cylindrical portion near the larger edge and a flat area at the side of the blank hole is mandatory. Such conditions allow producing conical parts with minimal thickness variation by altering height of the cylindrical portion. Conducted experimental studies showed that the minimal thickness variation values are not exceeding 16% for different materials and relative thicknesses less than 0,01.

Simulation of Material Flow Coupled with Die Analysis in Complex Shape Extrusion

The paper presents recent studies in simulation of thin profile extrusion technology with the emphasis on interaction between the material flow and the state of the tooling set. To take into consideration die deflection and gradient of the temperature across the die and mandrel during the entire process cycle a transient coupled thermo-mechanical model has been built on the basis of QForm-Extrusion program. The paper explains the background for this model and some tests to verify its accuracy. Practical implementation of this model at several die making and extrusion companies has shown it to be of higher accuracy compared to the results of rigid die simulation.

The Effect of Sintering Temperature on Microstructure and Properties of Al – SiC Composites / Wpływ Temperatury Spiekania Na Mikrostrukture I Własnosci Kompozytów Al – SiC

Attempts have been made to describe the influence of sintering temperature on the microstructure and properties of Al - SiC composites. Mixtures of 100%Al and Al - 5% SiC, Al - 10% SiC were produced by tumbling for 30 minutes in the Turbula T2F mixer. The powders were subsequently cold pressed at pressure 300MPa in a rigid die on a single action press. The green compacts were sintered in nitrogen at 580°C and 620°C for one hour. The main objective of this work was to determine influence of chemical composition and the manufacturing parameters on microstructure and properties of Al - SiC composites produced by powder metallurgy technology.

Computer Aided Modelling of Rubber Pad Forming Process

Rubber pad forming (RPF) is a novel method for sheet metal forming that has been increasingly used for: automotive, energy, electronic and aeronautic applications [1]. Compared with the conventional forming processes, this method only requires one rigid die, according to the shape of the part, and the other tool is replaced by a rubber pad [1]. This method can greatly improve the formability of the blank because the contact surface between the rigid die and the rubber pad is flexible. By this way the rubber pad forming enables the production of sheet metal parts with complex contours and bends. Furthermore, the rubber pad forming process is characterized by a low cost of the die because only one rigid die is required [2]. The conventional way to develop rubber pad forming processes of metallic components requires a burdensome trial-and-error process for setting-up the technology, whose success chiefly depends on operator’s skill and experience [4][5]. In the aeronautical field, where the parts are produced in small series, a too lengthy and costly development phase cannot be accepted. Moreover, the small number of components does not justify large investments in tooling. For these reasons, it is necessary that, during the conceptual design, possible technological troubles are preliminarily faced by means of numerical simulation [4],[6]. In this study, the rubber forming process of an aluminum alloy aeronautic component has been explored with numerical simulations and the significant parameters associated with this process have been investigated. Several effects, depending on: stamping strategy, component geometry and rubber pad characterization have been taken into account. The process analysis has been carried out thanks to an extensive use of a commercially finite element (FE) package useful for an appropriate set-up of the process model [7],[8]. These investigations have shown the effectiveness of simulations in process design and highlighted the critical parameters which require necessary adjustments before physical tests.