In Process Control of Strain in a Stretch Forming Process

2000 ◽  
Vol 123 (4) ◽  
pp. 496-503 ◽  
Author(s):  
D. E. Hardt ◽  
W. A. Norfleet ◽  
V. M. Valentin ◽  
A. Parris
Keyword(s):  
Point Of View ◽  
Experimental Point ◽  
Shape Variation ◽  
Stretch Forming ◽  
Forming Process ◽  
Strain Control ◽  
Variation Reduction ◽  
Full Production ◽  
Large Sheet

The process of stretch forming is used extensively in the aerospace industry to form large sheet panels of mild curvature. This has traditionally been a low precision process requiring considerable hand-working at assembly. However, recent demands for faster, less wasteful production have placed new demands on the accuracy and consistency (quality) of this process. In this paper the various modes of control for this process are examined, from both an analytical and experimental point of view. It is shown clearly that the process is least sensitive to material and machine property variations if controlled to a target level of strain in specific areas of the sheet. This method is compared with the conventional methods of controlling either the force applied to the sheet during stretching or the displacement of the stretch jaws. A series of both lab scale and full production experiments concur with the analytical findings, demonstrating reduced process variation if strain feedback is used. Lab experiments and analysis indicate that far greater reductions are possible if a more precise form of strain control is used. In production trials forming wing leading edges, a manually implemented strain control showed a shape variation reduction of 50 percent over normal factory practice using force control.

In Process Control of Strain in a Stretch Forming Process

2000 ◽  
Author(s):  
D. E. Hardt ◽  
W. A. Norfleet ◽  
V. M. Valentin ◽  
A. Parris
Keyword(s):  
Point Of View ◽  
Experimental Point ◽  
Shape Variation ◽  
Stretch Forming ◽  
Forming Process ◽  
Strain Control ◽  
Variation Reduction ◽  
Full Production ◽  
Large Sheet

Abstract The process of stretch forming is used extensively in the aerospace industry to form large sheet panels of mild curvature. This has traditionally been a low precision process requiring considerable hand-working at assembly. However, recent demands for faster, less wasteful production have placed new demands on the accuracy and consistency (quality) of this process. In this paper the various modes of control for this process are examined, from both an analytical and experimental point of view. It is shown clearly that the process is least sensitive to material and machine property variations if controlled to a target level of strain in specific areas of the sheet. This method is compared with the conventional methods of controlling either the force applied to the sheet during stretching or the displacement of the stretch jaws. A series of both lab scale and full production experiments concur with the analytical findings, demonstrating reduced process variation if strain feedback is used. Lab experiments and analysis indicate that far greater reductions are possible if a more precise form of strain control is used. In production trials forming wing leading edges, a manually implemented strain control showed a shape variation reduction of 50% over normal factory practice using force control.

Study of Multi-Point Flexible Floating Clamping System of Multi-Roll Stretch Forming Process

2011 ◽  
Vol 291-294 ◽  
pp. 282-285 ◽  
Author(s):  
Hao Han Zhang ◽  
Ming Zhe Li ◽  
Wen Zhi Fu ◽  
Xue Chen
Keyword(s):  
Finite Element ◽  
Finite Element Simulations ◽  
Metal Sheet ◽  
Stretch Forming ◽  
Forming Process ◽  
Clamping System

Multi-Roll Stretch forming process is a new flexible process which is used for forming hyperbolic-degree surface pieces. Using the Multi-point flexible floating clamping system, the metal sheet can be more easily formed, and the flexibility can be much higher, which the ordinary floating clamping cannot have. A series of finite element simulations and experiments have been done for the process of forming saddle-shaped parts using Multi-Point flexible floating clamping system, and ordinary floating clamping system. The results show that the quality of the part formed using flexible floating clamping system is better.

scholarly journals Adaptive Stretch-Forming Process: A Computer Vision and Statistical Analysis Approach

Machines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 357
Author(s):  
Cosmin Constantin Grigoras ◽  
Valentin Zichil ◽  
Bogdan Chirita ◽  
Vlad Andrei Ciubotariu
Keyword(s):  
Computer Vision ◽  
Classical Method ◽  
Industrial Process ◽  
Industrial Sector ◽  
Production Costs ◽  
Stretch Forming ◽  
Forming Process ◽  
Part Quality ◽  
High Degree

An industrial process is defined through its quality of parts and their production costs. Labour-intensive operations must be applied to produce high-quality components with inexpensive resources. Recent development in dedicated software allows the industrial sector to rely on more and more autonomous solutions to obtain an optimum ratio between part quality and cost. The stretch forming process is an operation that has a high degree of difficulty, due to the process parameters and the spring-back effect of materials. Our approach to solving several of the shortcomings of this process was to develop a self-adaptive algorithm with computer vision capabilities that adapts to the process in real-time. This experimental study highlights the results obtained using this method, as well as a comparison to a classical method for the stretch-forming process (SFP). The results have noted that the stretch-forming algorithm improves the process, while adapting its decisions with each step.

scholarly journals Experimental Research on the Behaviour of Metal Active Gas Tailor Welded Blanks during Single Point Incremental Forming Process

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 198
Author(s):  
Valentin Oleksik ◽  
Dan Dobrota ◽  
Sever-Gabriel Racz ◽  
Gabriela Petruta Rusu ◽  
Mihai Octavian Popp ◽  
...  
Keyword(s):  
Optical Measurement ◽  
Incremental Forming ◽  
Single Point ◽  
Welding Process ◽  
Force Transducer ◽  
Point Of View ◽  
Experimental Point ◽  
Single Point Incremental Forming ◽  
Forming Process ◽  
Tailor Welded Blanks

The present paper aims to study the behaviour of Metal Active Gas (MAG) tailor welded blanks during the single point incremental forming process (SPIF) from an experimental point of view. The single point incremental forming process was chosen for manufacturing truncated cone and truncated pyramid shaped parts. The same material (S355) and the same thickness (0.9 mm) were selected for the joining of blank sheets because the main goal of the paper was to study the influence of the MAG welding process throughout the SPIF process. A Kuka robot, equipped with a force transducer and an optical measurement system were used for manufacturing and evaluating the parts by SPIF. The selected output data were major and minor strain, thickness reduction, forces and springback at the SPIF process. Another line test was performed to evaluate the formability in SPIF. The main conclusion of the paper is that during the SPIF process, fractures occur in one side welded blanks even at moderate wall angles, while in the case of double side welded blanks there is a decrease of formability but parts can still be produced at moderate angles (55 degrees) without any problems.

Determination of Tool Motions in Stretch Forming Process for Aerospace Applications by Using Finite Element Method

2013 ◽  
Vol 554-557 ◽  
pp. 1451-1456 ◽  
Author(s):  
Hasan Ali Hatipoglu ◽  
Celal Onur Alkas ◽  
Celalettin Karadogan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Material Characterization ◽  
Element Model ◽  
Aircraft Industry ◽  
Stretch Forming ◽  
Forming Process ◽  
Aerospace Applications ◽  
Large Sheet

Stretch forming process is commonly used in the aircraft industry for the manufacturing of large sheet panels. The success of this process is highly dependent on the tool motions during forming. These motions are determined by trial - error procedure and it is costly. This study aims to optimize the stretch forming process by determining the necessary tool motions with numerical analysis. For this purpose, finite element model (FEM) of the process is established. Material characterization and friction tests of mostly used aluminum alloys are conducted for input to the model. In order to improve the model and validate the numerical results, experimental work will be performed in which the deformation of the sheet is measured optically.

High-Tc superconductors from the experimental point of view

1988 ◽  
Vol 156 (9) ◽  
pp. 117-135 ◽  
Author(s):  
L.P. Gor'kov ◽  
N.B. Kopnin
Keyword(s):  
Point Of View ◽  
Experimental Point

COMBINATORIAL POLYNOMIALLY COMPUTABLE CHARACTERISTICS OF SUBSTITUTIONS AND THEIR PROPERTIES

2020 ◽  
Vol 7 (2) ◽  
pp. 34-41
Author(s):  
VLADIMIR NIKONOV ◽  
◽  
ANTON ZOBOV ◽  
Keyword(s):  
Mathematical Expectation ◽  
Point Of View ◽  
Small Range ◽  
Computational Point ◽  
Wide Range ◽  
Bijective Function ◽  
The Difference ◽  
Element Base ◽  
Selection Of

The construction and selection of a suitable bijective function, that is, substitution, is now becoming an important applied task, particularly for building block encryption systems. Many articles have suggested using different approaches to determining the quality of substitution, but most of them are highly computationally complex. The solution of this problem will significantly expand the range of methods for constructing and analyzing scheme in information protection systems. The purpose of research is to find easily measurable characteristics of substitutions, allowing to evaluate their quality, and also measures of the proximity of a particular substitutions to a random one, or its distance from it. For this purpose, several characteristics were proposed in this work: difference and polynomial, and their mathematical expectation was found, as well as variance for the difference characteristic. This allows us to make a conclusion about its quality by comparing the result of calculating the characteristic for a particular substitution with the calculated mathematical expectation. From a computational point of view, the thesises of the article are of exceptional interest due to the simplicity of the algorithm for quantifying the quality of bijective function substitutions. By its nature, the operation of calculating the difference characteristic carries out a simple summation of integer terms in a fixed and small range. Such an operation, both in the modern and in the prospective element base, is embedded in the logic of a wide range of functional elements, especially when implementing computational actions in the optical range, or on other carriers related to the field of nanotechnology.

Physical capital stock, technological upgrading and modernisation in Hungary

2005 ◽  
Vol 55 (2) ◽  
pp. 201-221 ◽  
Author(s):  
Andrea Szalavetz
Keyword(s):  
Capital Accumulation ◽  
Physical Capital ◽  
Developed Countries ◽  
Point Of View ◽  
Technology Generation ◽  
Development Policies ◽  
Specific Factors ◽  
Physical Capital Accumulation

This paper discusses the relation between the quality and quantity indicators of physical capital and modernisation. While international academic literature emphasises the role of intangible factors enabling technology generation and absorption rather than that of physical capital accumulation, this paper argues that the quantity and quality of physical capital are important modernisation factors, particularly in the case of small, undercapitalised countries that recently integrated into the world economy. The paper shows that in Hungary, as opposed to developed countries, the technological upgrading of capital assets was not necessarily accompanied by the upgrading of human capital i.e. the thesis of capital skill complementarity did not apply to the first decade of transformation and capital accumulation in Hungary. Finally, the paper shows that there are large differences between the average technological levels of individual industries. The dualism of the Hungarian economy, which is also manifest in terms of differences in the size of individual industries' technological gaps, is a disadvantage from the point of view of competitiveness. The increasing differences in the size of the technological gaps can be explained not only with industry-specific factors, but also with the weakness of technology and regional development policies, as well as with institutional deficiencies.

Flouride and Nitrate Status of Some Ground Waters in Chittor District of Rajasthan State (India)

2018 ◽  
Vol 6 (9) ◽  
pp. 119
Author(s):  
Trapti Sharma ◽  
R. P. Nagar ◽  
R. C. Gaur ◽  
Pooja Gupta ◽  
Charanjit Kaur
Keyword(s):  
Point Of View ◽  
World Health ◽  
Indian Council ◽  
Standard Methods ◽  
Ground Waters ◽  
Drinking Waters ◽  
Health Organization ◽  
Research World ◽  
Drinking Purpose

In Rajasthan state the ground waters of some areas like Ramganj-mandi, Morak, Barmer, Jaisalmer, Chittor and Udaipur etc. are susceptible from drinking point of view.To test the quality of groundwater in Chittor district 14, ground water samples were collected from various places and analyzed for pH, E.C., Fluoride and Nitrate parameters by standard methods (A.P.H. A., Washington, USA, 1995). The study revealed that none of the ground waters was found suitable completely from drinking point of view. Some are having electrical conductivity > 1.4 dS/m, some are having pH >8.5, some area having fluoride >1.5 ppm and some are having nitrate>45 ppm. These are the limits of various parameters permitted by various International authorities like Bureau of Indian Standard, Indian Council of Medical Research,world health Organization etc. for drinking waters. So, it is recommended to the residents of above areas to use water for drinking purpose only after reverse osmosis or adopting suitable method of removing excess of Fluoride and Nitrate for drinking water to avoid unwanted pathogenic diseases harmful for human health.

A Futures Study on the Quality Of Life from the Point Of View of Iranian Youth

2017 ◽  
Vol 14 (2) ◽  
pp. 1
Author(s):  
Sina Saeedy ◽  
Mojtaba Amiri ◽  
Mohammad Mahdi Zolfagharzadeh ◽  
Mohammad Rahim Eyvazi
Keyword(s):  
Quality Of Life ◽  
Life Satisfaction ◽  
Mixed Model ◽  
Satisfaction With Life ◽  
Point Of View ◽  
Human Society ◽  
Futures Studies ◽  
The Social ◽  
The University

Quality of life and satisfaction with life as tightly interconnected concepts have become of much importance in the urbanism era. No doubt, it is one of the most important goals of every human society to enhance a citizen’s quality of life and to increase their satisfaction with life. However, there are many signs which demonstrate the low level of life satisfaction of Iranian citizens especially among the youth. Thus, considering the temporal concept of life satisfaction, this research aims to make a futures study in this field. Therefore, using a mixed model and employing research methods from futures studies, life satisfaction among the students of the University of Tehran were measured and their views on this subject investigated. Both quantitative and qualitative data were analysed together in order to test the hypotheses and to address the research questions on the youth discontentment with quality of life. Findings showed that the level of life satisfaction among students is relatively low and their image of the future is not positive and not optimistic. These views were elicited and discussed in the social, economic, political, environmental and technological perspectives. Keywords:  futures studies, quality of life, satisfaction with life, youth

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