Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2019 ( 4 )

2018 ( 102 )

2017 ( 97 )

2016 ( 136 )

Custom range...

Search Results: 1 - 10 of 2550 matches for " Plastic forming "
All listed articles are free for downloading (OA Articles)
Page 1 /2550
Display every page Item
Sheet Bending Deformation in Production of Thin-Walled Pipes  [PDF]
Tatjana V. Brovman
World Journal of Mechanics (WJM) , 2014, DOI: 10.4236/wjm.2014.412035
Abstract: Nowadays, thin-walled super-diameter pipes are produced by the method of plastic bending of sheets. After a sheet is bent into a pipe and its ends are welded, a pipe billet is subjected to expansion deformation. The technology of forming end areas of a sheet is developed and formulaes forming forces equations are deduced. Experimental investigations of deformation are undertaken.
Employment of alumina suspension pad for v-bending of SUS304 strip
T. Ohashi,H. Chiba,H. Takano
Archives of Materials Science and Engineering , 2008,
Abstract: Purpose: Authors have suggested employment of dilatant fluid for metal forming tools, and report an applicationon v-bending of thin stainless steel strips in this paper.Design/methodology/approach: An alumina concentrated hard-sphere suspension is employed as dilatant fluidfor forming. The authors evaluated the suspension with backward extrusion test. Followed by SUS304 stainless stripwith 0.25mm thickness and 30mm width on the pad of the suspension with a v-bend punch.Findings: Behaviour of the suspension is revealed in the backward extrusion test. Migration of water takesimportant role in it. In v-bending test, including acute angle bending, the authors bend the strip with only the vbendpunch and the alumina concentrated hard-sphere suspension pad successfully. It is thought that forming loadis less than with general polyurethane tools.Research limitations/implications: Spring-back in partial bending, which is similar to the suggestedprocess, is larger than in bottoming and coining with dies and bending with polyurethane tools. Therefore, theauthors will evaluate the spring-back in the suggested process in further study.Practical implications: Polyurethane pad is used in bending process generally because of advantageous pointsin easy-design, and safe from scratch. However it has disadvantageous points in its limited life and necessityof large forming load. The alumina concentrated hard-sphere suspension can be employed for such a pad withunlimited life. In addition, such dilatant fluid can be applied on other metal forming process as easy tool.Originality/value: Employing dilatant fluid for forming tools is new idea. V-bending with an aluminaconcentrated hard-sphere suspension was attempted.
Deformations and forces analysis of single point incremental sheet metal forming
A. Petek,K. Kuzman,J. Kopa?
Archives of Materials Science and Engineering , 2009,
Abstract: 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.
Numerical determination of the forming limit diagrams
T. Pepelnjak,K. Kuzman
Journal of Achievements in Materials and Manufacturing Engineering , 2007,
Abstract: Purpose: At present the industrial practice demands a reliable determination of forming limits which assuresthe prediction of properly selecting the forming process in a digital environment. Therefore, technological limitsdefined with the forming limit diagrams (FLDs) have to be known. The experimental evaluation of FLDs forsheet metal is time consuming and demands expensive equipment. The experimental work could be omitted bypredicting the FLD with numerical simulations.Design/methodology/approach: The paper presents a methodology to determine the entire range of the FLDfor sheet metal in a digital environment. The Marciniak testing procedure simulated with the FEM programABAQUS was selected to determine the FLD. To assure the reliability of the developed method, differentmaterials were analysed: two types of deep drawing steel, an aluminium 3000 alloy, and a Ti-alloy. The selectedmaterials have different mechanical properties and sheet thicknesses ranging from 0.5 mm to 1.23 mm. For theverification of numerically obtained results parallel experimental determinations of the FLDs were performedshowing a good correlation between the FLDs obtained by both approaches.Findings: A specially developed method for the evaluation of the thickness strain as a function of time as well asthe first and the second time derivation of the thickness strain enable the determination of the onset of necking.Research limitations/implications: The presented method of the digital evaluation of the FLDs is still ina developmental phase and needs further improvements for industrial practice. However, in some cases thenumerical approach had already been used for a fast prediction of the FLD prior to performing the experiments.At the current level the developed program still needs an expert to support it in some critical decisions.Originality/value: Considering some methodological improvements and automation procedures the developedmethod could be used in everyday practice.
Micro-forming of Al-Si foil
T. Haga,K. Inoue,H.Watari
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: 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 μm 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.
金属学报(英文版) , 2000,
Abstract: Metal flowing has been numerically simulated for synchronizer hub at different forming conditions. The influences of billet shape, frictional factor,deformation degree and radius of rounded corner on form- ing for been studied and the processing parameters have been optimized. On the basis, a new technol- ogy of refilling multiplicity forming has been put forward and workpiece that meets the requirement of synchronizer hub has been manufactured.
Examination of conditions in contact interface using ultrasonic measurement
H. Saiki,Y. Marumo,L. Ruan,T. Matsukawa
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: In metal forming, the conditions of contact interface have a great effect on the characteristics ofinterface friction and heat transfer between tool and workpiece. Estimation of contact conditions in the toolworkpieceinterface is required in order to optimize process conditions. Ultrasonic examination is an effectivemethod to estimate the contact conditions. In this study, we investigated the effects of ultrasonic frequencies andintermediate air/lubricant films in the contact interface on the properties of penetration and reflection of incidentultrasonic waves.Design/methodology/approach: We have presented a method by which the contact conditions are evaluatedfrom the relative intensity of reflected ultrasonic waves at the interface. Using this evaluation method, the relativeintensity was measured continuously during processes.Findings: The effects of ultrasonic frequencies and intermediate films on the properties of penetration andreflection of incident ultrasonic waves were revealed. The presented method was effective for evaluating thevariation of contact interface conditions.Research limitations/implications: Thickness of intermediate films can be measured using this ultrasonicexamination. The performance of lubricants can be estimated.Practical implications: The optimization of forming processes will be achieved based on the evaluation resultsof contact conditions.Originality/value: Tribological conditions including intermediate air/lubricants were evaluated by ultrasonicexamination. This shows the possibility that the lubricant behaviour in the contact interface is examined duringprocesses.
Forming of the titanium implants and medical tools by metal working
J. Adamus
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: of this paper is to present some technological problems with forming of the titanium implants and medical tools by the plastic working methods.Design/methodology/approach: Application of the new biomaterials such as titanium alloys needs to carry on tests on optimisation of the methods and parameters of the plastic working, therefore some experiments in order to determine the friction coefficient or analyse the influence of the cutting methods on the cut-surface appearance were done.Findings: As far as stamping is concerned, it was found that the proper lubrication not only decreases frictional resistance but also limits or even completely eliminates creation of the titanium “build-ups” on the tools. As far as cutting methods are concerned, the cut-surface significantly depends on the applied cutting method. Guillotining, laser and abrasive waterjet cutting were taken into consideration. Guillotining and laser cutting influence the titanium microstructure mostly. Abrasive waterjet cutting does not cause any changes in microstructure.Research limitations/implications: An application for the implants almost unworkable biomaterials, such as titanium alloys, needs overcoming many technological barriers such as proper selection of the lubricant, deformation temperature, strain velocity etc. Moreover, titanium belongs to the very expensive materials, so material costs are the main research limitation.Practical implications: The investigations of the friction coefficient or the influence of the cutting method on the cut-surface quality are important for producing both implants and surgical tools by such methods as: cutting, blanking, bending, stamping, etc.Originality/value: There are only a very few works on the sheet-metal forming processes of the titanium alloys, so each new information on the titanium deformation is valuable.
Structure of polypropylene parts from multicavity injection mould
T. Jaruga,E. Boci?ga
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: The examination of structure of injection moulded parts, coming form different cavities of injection mould with geometrically balanced runners, was the purpose of this research. The parts were manufactured from polypropylene.Design/methodology/approach: The method of optical microscopy was used. The samples were prepared from microtomed slices from parts and next they were observed in polarized light. The skin-core morphology was analyzed and spherulitic structure was described by spherulites size measuring.Findings: The differences in morphology and spherulite size for parts from particular mould cavities were found. They are caused by different thermal conditions in each cavity.Research limitations/implications: An injection mould with geometrically balanced runners was used for investigation. The differences in parts’ structure occur for each injection mould, but they are dependent on the cavities layout and runners configuration.Practical implications: Knowledge about the differences in structure of parts from different cavities is the reason to look to the solution by minimizing the temperature inequality in the injection mould.Originality/value: Despite using geometrically balanced runners the cavities are not filled equally and the parts have different structure. In some recent works the issue of flow imbalance in multicavity injection moulds was analyzed and even some solutions of this problem were proposed. All investigation was focused on simultaneous plastic flow into all cavities, but there were no investigation of parts’ structure and properties.
Crystallinity of parts from multicavity injection mould
T. Jaruga,E. Boci1ga
Archives of Materials Science and Engineering , 2008,
Abstract: Purpose: The intention of this research was to test, if injection moulded polyoxymethylene parts, manufactured indifferent cavities of the multicavity injection mould with geometrically balanced runners, differ in crystallinity degree.Design/methodology/approach: The values of crystallinity degree were calculated on the basis of DSC(Dynamic Scanning Calorimetry) testing method results (DSC curves).Findings: It was found that there are differences in crystallinity degree for parts from particular mould cavities.The reason of this is the difference in thermal conditions, specific for each cavity.Research limitations/implications: It is supposed that the parts from each multicavity injection mouldwould have differences in properties. However, it is always dependent on cavities and runners’ layout. Since in thisresearch a particular injection mould was used, the conclusions can not be directly extrapolated to other moulds.Each case requires its own analysis. Higher crystallinity degree will occur in parts obtained from areas of highermould temperature.Practical implications: The results of this investigation are important for mould designers, especially whenmoulds are used for precision injection moulding. It was proved here that differences in parts’ properties can occurfor multicavity injection moulds. In order to avoid this it is required to minimize the temperature differences inthe mould.Originality/value: Geometrically balanced runners in the mould were supposed to assure the equal filling of allcavities. The results obtained lately by other researchers have shown that this is not always true. That investigationwas mostly focused on filling imbalance that leads for example to difference in weight of parts from differentcavities. In this paper it was shown that not only weight of parts can differ but also other properties.
Page 1 /2550
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.