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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

Abbas Enas Abdulsada, Mansor Khalida Kadhim

Advances in Science and Technology. Research Journal

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2023

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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

Improve Single Point Incremental Forming Process Performance Using Primary Stretching Forming Process

Bedan Aqeel Sabree, Shabeeb Alaa Hassan, Hussein Emad Ali

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 5

260--268

EN

Incremental forming (IF) is one of the sheet metals forming technique where is a sheet formed into a final workpiece using a series of small incremental sheet deformations. In Incremental sheet metal forming process, one of the important steps is to produce the forming part with acceptable performance such as product accurate and uniform thickness distribution with a homogenous grain distribution that consider as the main challenge of incremental sheet metal forming process. This work is carried out to find the best method to control the product performance of the final parts using a new method of applying a primary stretching forming process with a hemispherical forming tool followed by single point forming SPIF. Different primary forming depth (10, 20, 30 and 40 mm) were applied to find their effect on the forming behavior of the final product and compare them to the single point forming product without using a primary forming process. The experimental results showed the improvement in microstructure by applying SPIF process after primary stretching, with grain size of 36 µm at 40 mm forming depth as compared to 52 µm when using pure SPIF, a twining effects presence in both cases. A high improvement with a minimum dimension deviation of (6%) with respect to the forming process in single point incremental forming process without a primary forming process that result forming deviation equal to (11.6%) with respect to the desired design. The thickness distribution of the final product also improved by applying the primary stretching forming process before the SPIF process reaches to (6.9%, 9.1%, 14.9% and 21.5%) at forming depth (10, 20, 30 and 40) mm, respectively.

3

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

Cui Xiao-Lei, Yuan Shijian

Archives of Civil and Mechanical Engineering

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2021

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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.

4

Badanie rozkładu grubości powierzchni cienkich warstw metodą elipsometrii spektroskopowej

Hajduk Barbara, Jarka Paweł, Nitschke Paweł

LAB Laboratoria, Aparatura, Badania

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2019

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R. 24, nr 1

6--8

5

The effect of selected conditions in a thermoforming process on wall thickness variations

Sasimowski E.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 4

41--48

EN

The paper reports the results of a study on the effect of selected conditions in a thermoforming process for thin polystyrene sheet by vacuum assisted drape forming on the wall thickness non-uniformity of finished parts. The investigation was performed using Statistica’s DOE module for three variables: temperatures in the external and internal zones of the heater as well as heating time of the plastic sheet. The results demonstrate that the wall thickness in the finished parts at the measuring points is primarily affected by the heating time and the temperature in the internal zone of the heater, while the temperature in the external zone only affects some regions of the finished part. The results demonstrate that a short heating time, and hence, a lower temperature of the plastic sheet lead to a more uniform deformation of both the bottom and the side walls of the finished part, and as a consequence, to smaller variations in the wall thickness. Shortening the heating time is, however, limited by the necessity of accurate reproduction of the shape of the finished part.

6

The effect of process parameters on thickness distribution in thermoforming

Ekşi O., Karabeyoğlu S. S.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 2

198--204

EN

In this study, cylindrical, conical and hemispherical molds were used to form flat thermoplastic sheets which are 1.5 mm in thickness. The effect of plug assist on thickness distribution was investigated. The sheets were formed with and without plug assist. Then thickness distributions on thermoformed products were obtained for two experimental procedures by a digital caliper (Resolution: 0.01 mm). As a result, plug assist thermoforming provides more uniform thickness distributions than negative forming.

7

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

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

Rudy i Metale Nieżelazne Recykling

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2016

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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.

8

Investigations of thickness distribution in hole expanding of thin steel sheets

Frącz W., Stachowicz F., Trzepieciński T.

Archives of Civil and Mechanical Engineering

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2012

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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.

9

Estimation of hole-flange ability for deep drawing steel sheets

Stachowicz F.

Archives of Civil and Mechanical Engineering

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2008

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Vol. 8, no 2

167-172

EN

Hole-flanging is a common sheet forming operation to produce structural sheet metal components. Flanges are used for appearance, rigidity, hidden joints, and strengthening of the edge of sheet metal parts. Trial-end-error is the most common approach for tooling and proces s design in flanging operations. This paper presents some experimental results of hole-flanging process performed on flat deep drawing steel sheets with circular hole drilled in the centre. Three punches of different geometry i.e. cylindrical, hemispherical and conical werce used in this experiment. The effect of both the punch geometry and material mechanical parameters (especially strain hardening and plastic anisotropy) on the limit expansion of the hole was determined.

PL

Proces wywijania krawędzi wokół otworów jest często stosowany w konstrukcjach wykonywanych z blach. Wywinięcia krawędzi obrzeża wykonywane są by umożliwić wykonanie połączenia, bądź też w celu zwiększenia sztywności lub wytrzymałości konstrukcji. Metoda prób i błędów jest częstym sposobem doboru geometrii narzędzi oraz technologii wywijania. Opracowanie to zawiera wyniki badań eksperymentalnych procesu wywijania kołnierza wokół otworów wywierconych lub wykrojonych w próbkach blach stalowych o różnej tłoczności, przy zastosowaniu trzech różnych geometrii stempla - płaskiej stożkowej oraz kulistej. Określono wpływ geometrii stempla oraz właściwości mechanicznych materiału (wykładnik krzywej umocnienia oraz współczynnik anizotropii) na wartość maksymalnego stopnia wywinięcia.