Wyniki wyszukiwania - Biblioteka Nauki

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Numerical and Experimental Investigation of the Effect of Strength of Aluminum 6061 Alloy on Thickness Reduction in Single-Point Incremental Forming

100%

Abbas E. A. , Mansor K. K.

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tom Vol. 17, no 4

271--281

EN

Single-point incremental forming (SPIF) is a kind of incremental sheet forming that is significantly novel. This method involves the utilization of a computer numerical control (CNC) machine to control the path of a forming tool, which is produced by a computer-aided manufacturing program (CAM), as it stretches a metallic sheet to achieve a desired shape. Low patch output and customized parts are good candidates for this kind of technique. The aim of the present investigation is first to study the effect of Aluminum alloy 6061 strength on the thickness distribution and thinning ratio in SPIF and then select the optimal strength to ensure uniform thickness and minimize the thinning. In order to achieve this, two different strengths of Al 6061 sheets have been employed: One used in its original form and the other heat-treated to change its strength. Specimens have been prepared using the SPIF procedure for a truncated cone with dimensions of 120 mm diameter and 40 mm depth; the forming slope is 50°, and Solid work program was used to create the tool path. The thickness reduction along the wall portions was analyzed employing the finite element method using Abaqus software, and the numerical results were experimentally confirmed, where the deviation ratio between simulation and experiment was 2% for sample 1 and 5% for sample 2. The findings manifested that the specimens exhibited a consistent distribution of thickness, and the maximum thinning ratio decreased from 30% to 28.5% as the yield strength decreased from 278 MPa to 68.7 MPa, respectively.

2

Investigations of thickness distribution in hole expanding of thin steel sheets

86%

Frącz W. , Stachowicz F. , Trzepieciński T.

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tom Vol. 12, no. 3

279--283

EN

This work aims to investigate the effect of punch geometry on the sheet thickness distribution in the collar formed during hole-flanging process. Three different punch geometries: cylindrical (flat-bottomed), hemispherical and conical were used in the experiment as well as in numerical simulation. Extra deep drawing quality (EDQ) steel sheet with a thickness of 1.0 mm was selected for this work. The results of experimental investigations were compared with the results of numerical modeling performed using the FE based MSC.Marc +MENTAT computer code.

3

Influence of forming temperature on formability and wall thinning in drawpieces made of Ti6Al4V alloy

72%

Rękas A. , Latos T. , Zygmunt K. , Zaborowski K. , Kurek M.

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tom R. 61, nr 3

115--120

EN

Plastic deformation of products made of Ti6Al4V alloy is possible only in elevated temperature. A toolset was developed for obtaining 3 variants of drawpieces which had the same drawing degree and various heights of a side wall. The research allowed for obtaining 1 drawpiece without a flange and 2 drawpieces with flanges of various diameters. The research was carried out in 350, 375, 400, 425 and 450°C which allowed to define optimal conditions for the test. For each variant of a drawpiece, material thinning along the cross-section was analysed in different temperatures.

PL

Odkształcenie plastyczne wyrobów ze stopu tytanu Ti6Al4V możliwe jest jedynie w podwyższonych temperaturach. Opracowano zestaw narzędziowy umożliwiający uzyskanie wytłoczek w trzech wariantach mające ten sam stopnień wytłaczania, ale różną wysokość ścianki bocznej. Badania pozwoliły na uzyskanie w jednej próbie wytłoczki bez kołnierza oraz dwóch wytłoczek z kołnierzem o różnej średnicy. W celu wyznaczenia optymalnych warunków do badań przyjęto temperatury 350, 375, 400, 425 oraz 450°C. Analizowano pocienienie materiału wzdłuż tworzącej wytłoczki dla każdego z trzech wariantów wysokości ścianki bocznej oraz porównano je dla każdej z analizowanych temperatur.

4

Analysis of thickness variation and stress state in hydroforming of complex T-shaped tubular part of nickel-based superalloy

72%

Cui X.-L. , Yuan S.

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tom Vol. 21, no. 3

458--471

EN

Stress states on a multi-branch tubular part are the most complicated change in all types of hydroforming process, which result in severe variation of thickness. In this paper, an experimental and numerical research was conducted on a multi-step hydroforming process including intermediate annealing treatment to obtain effect of stress state on the thickness variation of a superalloy GH4169 complex T-shaped tubular part with expanded diameter, which corresponds to a real product used in aerospace industry. The material flow behavior at typical points on hydroformed tube blank was first analyzed. Then, the thickness variation on the hydroformed GH4169 tube blanks was discussed in every step. It is shown that the materials have different flow directions to form the side branch, where the thickness is always thinned during the four-step hydroforming process. Large axial feeding induces a continuous thickening between transition areas and tube ends. The thickness invariant dividing line in the side branch zone moves toward the tube ends with forming going on. However, in the hemisphere zone, it moves slightly towards the center of the side branch. Moreover, the stress states at three typical positions, as well as their effect on the thickness variation, were analyzed based on a sequential correspondence law between stress and strain components. On this basis, the mechanism of thickening in the left transition area, thinning at the top of side branch and thickness variation at the hemispheric pole was revealed. These results are very important for obtaining the thickness distribution of a complex T-shaped tubular part in multi-step hydroforming, and revealing the thickness variation mechanism by using engineering plasticity theory.

5

Badanie rozkładu grubości powierzchni cienkich warstw metodą elipsometrii spektroskopowej

72%

Hajduk B. , Jarka P. , Nitschke P.

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tom R. 24, nr 1

6--8