Wyniki wyszukiwania - Biblioteka Nauki

1

The role of quality control operations in a process of plastic forming

100%

Topolska S.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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tom Vol. 23, nr 2

95-98

EN

Purpose: The aim of this paper is present the role of quality control operations in such a complex manufacturing process like plastic forming. Nowadays classical manufacturing process management is replaced with total quality management philosophy. Design/methodology/approach: The presented results base on the investigations conducted in manufacturing plants of heavy industry. Next the results of researches have been compared with requirements of quality standards. Findings: Results obtained in the work point the importance of a system of continuous quality monitoring and of quality control operations. Moreover the improvement in quality management is directly related with the corporate image. Research limitations/implications: The presented results base on the analysis of manufacturing processes of steel mills and are considered with the process of plastic forming and related processes. It must be stated that some technological parameters are confidential. Practical implications: The practical implication of the work is considered with the proposal of a scheme of quality control operations in a manufacturing process of plastic forming. This scheme could be used as a remark showing the proper manufacturing process planning. Originality/value: The work presents the analysis of manufacturing processes for heavy industry according the quality assessment what is rather a lateral problem in quality analysis.

2

Optimization of extrusion force prediction model using different techniques

75%

Jurkovic Z. , Jurkovic M. , Buljan S.

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tom Vol. 17, nr 1-2

353--356

EN

Purpose: This research is determination of the optimal cold forward extrusion parameters with objective the minimization of tool load. Design/methodology/approach: This paper deals with the different optimization approaches relating to determine optimal values of logarithmic strain, die angle and coefficient of friction with the purpose to find minimal tool loading obtained by cold forward extrusion process. To achieve this, it has been carried out two experimental plans based on factorial design of experiment and orthogonal array. By using these plans it was performed classical optimization, according to response model of extrusion forming force, and the Taguchi approach, respectively. Findings: Experimental verification of optimal forming parameters with their influences on the forming forces was done. The experimental results showed an improvement in minimization of tool loading. It was compared results of optimal forming parameters obtained with different optimization approaches and based on that the analysis of the characteristics (features and limitations) of both techniques. Research limitations/implications: Suggestion for future research it will be application of evolutionary algorithms namely model prediction of the process by genetic programming and optimization of extrusion parameters by genetic algorithm. Practical implications: a practical (industrial) implication on the smallest energy consumption, longer tool life, better formability of the work material and the quality of the finished product. Originality/value: This paper is obtained original extrusion force model for experimental domain of forming parameters and identification of parameters influence in that model

3

Forging and rolling of magnesium alloy AZ61

75%

Greger M. , Kocich R. , Čižek L.

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tom Vol. 20, nr 1-2

447-450

EN

Purpose: The paper summarises results of experiments aimed at development of structure of modified alloy AZ61 at hot deformation. Design/methodology/approach: Deformation behaviour of alloy was verified at the temperature of 420 degrees centigrade by rolling at 380 degrees centigrade by forging, respectively. Findings: Magnesium alloy AZ 61 have hexagonal structure and their forming is at room temperatures very difficult, that's why big plastic deformations are carried out in hot condition. After plastic deformations was obtained that original grain size decreased 15 times. Research limitations/implications: This paper provide data about magnitude of deformation, strain rate and temperature of forming at different techniques of plastic deformation. It was aimed to determine the conditions for non problem rolling and forging respectively. Practical implications: Initial structure was as cast and after heat treatment T4. Heat treatment appeared much better for forming as well as forging than rolling because of state of stress. Originality/value: Role of beta phase (Mg17Al12) in these alloys at plastic forming is very important, such that how it was obtained, best final properties of AZ 61 alloy supports very fine particles, distributed into Mg matrix. Next a relevant information is that multi stage forming process is much better in comparison with a big single reduction.

4

A method for setting variables in Super Plastic Forming process

75%

Cappetti N. , Garofalo L. , Naddeo A. , Nastasia M. , Pellegrino A.

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tom Vol. 38, nr 2

187-194

EN

Purpose: Superplastic forming (SPF) technology exceeds the limit of standard presswork either of form or of thickness distribution, but the lead time and the energy expenditure are more onerous for industrial use. The aim of this work is to study the role that process parameters play in a superplastic forming manufacturing in order to minimize the processing times and the cost respecting the “total quality” of the finished product. Design/methodology/approach: Identified the basic parameters of SPF process that is the thickness of blank, the strain rate and the processing temperature, were chosen three different values for each of them. For each combination of parameters and using finite element software, a forming simulation of a sample part was made. Important parameters as thickness reduction, stress distribution, time/working pressure curve are calculated and evaluated. Findings: The obtained results were manipulated in order to create some global indicators that was analysed to study the reliance on process quality and production costs. Research limitations/implications: The other and more difficult to define parameters, such as cast and initial sheet shape, friction between cast and sheet, need to be evacuated because they also affect the optimisation process, as well as its affordability, that is the result of careful control of process variables. Practical implications: The highlighted dependencies are whatever useful, during process configuration, to drive production choices for quality improvement and cost reduction of superplastic formed components. Originality/value: The interesting result is that some dependencies are not as strong as expected from literature. As an example, the quality parameters dependence on the strain rate is no linear. So much as to the decrease of strain rate some indices worsen considerably.

5

Micro-forming of Al-Si foil

63%

Haga T. , Inoue K. , Watari H.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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tom Vol. 40, nr 2

115-122

EN

Purpose: of this paper is as below. The investigation of the ability of the cold micro-forming of non-metallic glass was purpose. The grain of the rapidly solidified aluminium alloy became fine. The aluminium alloy foil with fine grain was used, and the investigation of the micro-formability of this alloy was investigated. Moreover, increase of the forming speed was investigated. The increase of the forming speed was purpose of this study, too. Design/methodology/approach: The nozzle pressing melt spinning method was used to attain the rapid solidification of the non-metallic grass. The Al-14mass%Si, which is hyper eutectic but is close to eutectic, was used. The roll contact surface was formed by V-groove. The cold rolling was adopted for forming. The V-groove was machined at the roll surface. The micro-forming was operated at the cold work. Findings: Micro-forming of the crystal aluminium alloy was able by the cold work. The forming speed was 0.04S to form 10 ěm height. The forming speed could be drastically increased. Research limitations/implications: The angle of the V-groove, which was used in the present study, was only 60 degrees. The effect of the groove angle on the protrusion-height was not clear. The used material was only the Al-14mass%Si. Relationship between the material and protrusion-height was not clear. Practical implications: The die for the micro-forming of the resin could be made from economy material by the conventional cold rolling process at short time. Therefore, the mass production of the economy die for resin may be obtained. Originality/value: The micro-forming of the rapidly solidified non-metallic glass by cold work was original.

6

The physical modelling of a normalising rolling of plates of S460NL1 steel grade

63%

Knapiński M. , Markowski J.

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2007

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tom Vol. 28, nr 6

373-376

EN

Purpose: The aim of the present work was to demonstrate that, in laboratory conditions and using a physical simulator of metallurgical processes, it us possible to reflect the actual production process and, at the same time, to simulate new, not necessarily perfect rolling technologies, while not incurring any outlays on industrial lots of a new product line. Design/methodology/approach: The article present the results of physical simulations of the process of rolling plates of steel S460NL1 on the finishing stand of a reversing mill. The simulations were performed for three final plate thicknesses, namely 8, 10 and 12 mm. Findings: The purpose of the simulations was to select the conditions of band deformation with the aim of obtaining, directly after rolling, a material structure corresponding to the structure obtained from normalizing annealing. Thus, the simulations reflected the normalizing rolling process. Practical implications: The researches carried out has allowed to elaborate new technology of production of rolling plate without a additional thermal treatment like as normalisation. It allow to decrease a time and total cost of production for this sort of product. Originality/value: The investigation carried out has confirmed that it is possible to obtain and manufacture 8, 10 and 12 mm-thick plates of S460NL1 grade steel by normalizing rolling in the conditions of the plant under consideration.