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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.

2

Fracture limit analysis of DP590 steel using single point incremental forming: experimental approach, theoretical modeling and microstructural evolution

Pandre Sandeep, Morchhale Ayush, Mahalle Gauri, Kotkunde Nitin, Suresh Kurra, Singh Swadesh Kumar

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

138--157

EN

The single point incremental forming (SPIF) process is gaining special attention in the aerospace, biomedical and manufacturing industries for making intricate asymmetric components. In the present study, SPIF process has been performed for forming varied wall angle conical and pyramidal frustums using DP590 steel. Initially, the conventional stretch forming process has been performed for finding the fracture forming limit diagram (FFLD). Further, it has been validated with the limiting strains found using SPIF process. The conical and pyramidal frustums deformed near to the plane strain and biaxial region, respectively. The theoretical FFLD has been predicted using seven different ductile damage models. The effect of sheet anisotropy while predicting the fracture strains has been included using Hill 1948 and Barlat 1989 yielding functions. Among the used damage models, the Bao-Wierzbicki (BW) model along with Barlat 1989 yield criterion displayed the least error of 2.92% while predicting the fracture locus. The stress triaxiality in the different forming region has been thoroughly investigated and it has been found that the higher triaxiality value reveals high rate of accumulated damage which lead to early failure of the material in the respective region. The stress triaxiality and effective fracture strains have also been found to be significantly affected by the anisotropy. The micro-textural studies have also been performed and it has been found that the increase in local misorientations and shift in the textural components from γ-fiber to ε-fiber in the corner region of the frustums worked towards limiting the formability of material and ultimately leading towards the fracture of frustums.

3

Experimental analysis of single point incremental forming of truncated cones in DC04 steel sheet

Krasowski B., Kubit A., Trzepieciński T., Slota J.

Advances in Materials Science

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2020

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Vol. 20, nr 4(66)

5--15

EN

Experimental tests to form truncated cones were carried out on a 3-axis milling machine. 0.8-mm thick low-alloy DC04 steel sheets were used as test material. The profile tool-path trajectory was generated using the EDGECAM software. The slope angle and diameter of the base of the conical shaped drawpieces were 70°-72° and 65 mm, respectively. The drawpiece heights were up to 75 mm. The full synthetic lubricant 75W85 was used to reduce the frictional resistance. The effect of selected incremental forming parameters on the formability of the DC04 sheet and the susceptibility to crack formation have been analysed and discussed. It was found that the surface roughness of the workpiece is strongly influenced by step depth. By controlling the feed rate, it is possible to prevent failure of the material.

4

Single point incremental forming of Cu-Al composite sheets: A comprehensive study on deformation behaviors

Liu Zhaobing, Li Guohao

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 2

484--502

EN

Compared with monolithic metal sheet, Single Point Incremental Forming (SPIF) of bimetal composite sheet has attracted increasing attention, as it takes advantages of materials with different superior properties, such as high strength, low density, and good corrosion resistance. However, deformation behaviors of bimetal composite sheet in SPIF may differ from the single-layer sheet, which depends on the layer arrangements and mechanical properties of each layer. In this regard, a comprehensive study was conducted to investigate the deformation behaviors of roll-bonded Cu-Al composite sheets in SPIF through predictive modeling, including analytical, empirical as well as numerical approaches, and extensive experimental work taking into consideration effects of key process parameters. It was demonstrated that overall, the formability, surface roughness, thickness variation and forming force in different layer arrangements, in terms of various process parameters, follow the similar trends to single-layer sheets. However, it was further revealed that deformation mode of layer-up sheet tends to a compression state and that of layer-down sheet tends to a stretching state. This leads to higher formability and larger forming force in Al/Cu layer arrangement compared to Cu/Al layer arrangement, as the exterior thinner but stronger Cu layer could endure more stretching deformation.

5

Rozwój metod jednopunktowego tłoczenia przyrostowego na obrabiarkach CNC

Trzepieciński T., Kowalik M.

Mechanik

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2012

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R. 85, nr 1CD

PL

Artykuł zawiera charakterystykę metod przyrostowego kształtowania blach za pomocą następujących metod: jedno- (Single Point Incremental Forming) i dwupunktowego tłoczenia przyrostowego (Two Point Incremental Forming). Przedstawiono czynniki wpływające na możliwość zastosowania metody oraz zjawiska ograniczające stosowanie formowania przyrostowego blach. Wyszczególniono także wady i zalety omawianej metody kształtowania blach.

EN

The article includes characteristics of method of incremental forming of the sheet using two following methods: Single Point Incremental Forming and Two Point Incremental Forming. Factors influencing on possibility of method application and phenomena limiting using of incremental forming of the sheet have been presented. Disadvantages and advantages of discussed method of sheet forming have been also specified.

6

An evaluation of through - thickness deformation mechanisms in single point incremental sheet forming using a dual - level finite - element mode

Essa K., Hartley P.

Computer Methods in Materials Science

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2012

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Vol. 12, No. 1

37-50

EN

Single point incremental forming (SPIF) is a process with the capability to form complex geometries using a tool of very simple geometry, without the need for a matching die. At present, through-thickness modes of deformation and the existence of through-thickness shear are not clear. The objectives of this report are firstly, to establish a computational methodology to study the deformation mechanism of SPIF and secondly, to provide a clear description of the deformation modes that take place through the sheet thickness. The methodology is, in essence, a multi-level approach, although in this example only two levels are necessary. In this paper, a 3-D implicit finite-element (FE) model of the complete sheet being formed, with two elements through the thickness and a second-level FE model of a smaller segment of the sheet, with seven elements through its thickness, are used in a dual-level approach. The results show that the full model is capable only of exploring the principal characteristics of the deformation, normal strains and the final product geometries. The second-level model demonstrates a capability to predict more accurately the deformation modes through the sheet thickness and shows the influence of tool friction and diameter on the through-thickness shear strains. A combination of bending, stretching and thinning modes of deformation in addition to through thickness shear is found. The results obtained provide a more complete description of through-thickness deformation mechanisms.

PL

Jednopunktowa przyrostowa metoda kształtowania blach (ang. single point incremental forming - SPIF) jest procesem umożliwiającym uzyskiwanie skomplikowanych kształtów przy zastosowaniu prostych narzędzi. Nie jest potrzebna zgodność kształtu narzędzia i wyrobu. Stosowane obecnie modele tego procesu nie określają jednoznacznie zmian odkształcenia i ścinania na grubości blachy. Cele niniejszej pracy to po pierwsze opracowanie metody analizy mechanizmów odkształcenia w SPIF, a po drugie dostarczenie opisu schematów odkształcenia występujących w tym procesie wzdłuż grubości blachy. Zastosowano metodę podejścia wielopoziomowego, chociaż w rozważanym zadaniu potrzebne były tylko dwa poziomy. Dla kształtowanej blachy wykorzystano model implicit 3D na bazie metody elementów skończonych (MES), z dwoma elementami na grubości. Dla małego wycinka blachy zastosowano model MES drugiego poziomu z siedmioma elementami na grubości. Wyniki wykazały, że pełny model umożliwia ocenę tylko głównych charakterystyk odkształcenia, czyli odkształceń normalnych i kształtu wyrobu. Model drugiego poziomu przewiduje dokładniej schemat odkształcenia na grubości blachy i umożliwia ocenę wpływu tarcia i średnicy na rozkład odkształceń postaciowych wzdłuż grubości. Dodatkowo możliwy był opis połączonego wpływu zginania, rozciągania i pocienienia. W konsekwencji uzyskane wyniki dostarczają pełniejszego opisu mechanizmów odkształcenia na grubości blachy.

7

Deformations and forces analysis of single point incremental sheet metal forming

Petek A., Kuzman K., Kopač J.

Archives of Materials Science and Engineering

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2009

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Vol. 35, nr 2

107-116

EN

Purpose: In this paper the experimental equipment and design of the system for deformation and forming force measuring by single point incremental sheet metal forming are described. Beside this the analysis results of the impact of the wall angle, tool rotation, vertical step size, tool diameter and lubrication on the magnitude of forming force and plastic logarithmic strain are presented. Design/methodology/approach: The incremental sheet metal forming process was performed on the CNC controlled milling machine Moiri Seiki with the FANUC MSC-521 control system. The forming forces were measured using specially designed force measuring system which is connected with the milling machine. In contrast to force measuring, the deformations of the specimen were measured by using the graphometric analysis based on the size and direction investigation of the major strains of the particular sheet metal area. Findings: The results show that the forming force is very small in comparison to the deep drawing process and it does not depend on the product size. That is why the production of very large products is absolutely appropriate for forming. Beside this, the deformations and forces distribution are mostly dependent on the size of the wall angle of forming, tool diameter and vertical step sizes of the tool. Research limitations/implications: The deformations and forces analyses are researched only for the steel DC05 of 1 mm in thickness. Practical implications: The analysis results will help to improve the choice of the appropriate equipment and to setting of the optimal process parameters on the strain distribution and the size of needed forming force. By this the production time of the product could be reduced, which is otherwise by this process very long. Originality/value: A detailed deformations and forces analyses of single point incremental sheet metal forming for some combinations of process parameters used are original.