Papers by Keyword: Plastic Working

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Authors: Taro Tokuda, Takeshi Uemori, Tetsuya Yoshida, Michihiro Takiguchi, Fusahito Yoshida
Abstract: In sheet metal industries, press-formed sheet elements are usually adhesively bonded together at the final stage of assembly. Instead of such a conventional process, the present authors proposed a new technique that first flat sheets are adhesively bonded together and then press-formed into the final products. In previous study, the problem of the die-bending (V-bending and hat-shaped bending) with symmetrical shape has studied. In this study, asymmetric-shaped bending of adhesively bonded sheet metals was investigated by experiments and FEM analysis method. In the case of asymmetric-shaped bending, it was found that the timing of contact from the die corner to the die hypotenuse is early in the press-forming process compared with symmetrical bending (V-bending and hat-shaped bending). For the FEM analysis results, the maximum shear strain in asymmetric-shaped bending was smaller than that in symmetric-shaped bending at the hat-shaped side. Thus, the shape of the die has a large influence on the die-bending of adhesively bonded sheet metals.
Authors: Robert Jasionowski, Wojciech Polkowski, Dariusz Zasada
Abstract: Copper alloys due to their very good corrosion properties are often used to a fabrication of components that are subjected to both a cavitational destruction and a corrosive action of an environment, e.g.. ships’ propellers, sliding elements, pump parts etc. The course of cavitational destruction depends mainly on a material’s structure (a grain size, a type of inclusions, morphology and phase distribution, etc.) but also on the load distribution, and a possible activity of chemical, electrochemical and thermal processes near cavitation bubbles. Properties of a material that is subjected to the cavitational damage are strongly affected by its structure formed upon manufacturing or applied processing. In the present paper, results of the cavitational resistance analysis of CuZn10 alloy in the as cast state (the grain size of 200 μm) and after thermomechanical processing (the grain size of 10 or 200 μm) evaluated on vibrational laboratory stand in accordance with ASTM G-32 standard, are shown.
Authors: Michihiro Takiguchi, Taro Tokuda, Tetsuya Yoshida, Takeshi Uemori, Fusahito Yoshida
Abstract: In this paper, the deformation behavior of adhesive layer in stretch-bending/unbending for adhesively bonded sheet metals was investigated by experiments and finite element method (FEM). We paid special attention to the cyclic shear deformation of the adhesive layers during the plastic working. Major results obtained are summarized as follows: (1) When the adhesively bonded sheet metals is bent and pulled out at a 90° angle, shear deformation due to bending of the adhesive layer starts shortly before reaching the die corner and unbending starts at the middle of the corner. (2) The die radius has a large influence on the bending behavior. (3) It is possible to suppress shear deformation of the adhesive layer by using a material with small tensile strength as one of the two adherends.
Authors: Michihiro Takiguchi, Taro Tokuda, Tetsuya Yoshida, Takeshi Uemori, Fusahito Yoshida
Abstract: In this paper, the deformation behavior of adhesive layer in die-bending for adhesively bonded sheet metals was investigated by experiments and finite element method (FEM). We paid special attention to the bending/unbending shear deformation of the adhesive layer during the die-bending of adhesively bonded sheet metals by using highly ductile acrylic adhesive. Major results obtained are summarized as follows: (1) The bending/unbending shear deformation of the adhesive layer was observed during the die-bending. (2) The punch radius has a large influence on the die-bending in the adhesively bonded sheet metals. (3) It is desirable to perform die-bending at high speed as well as air-bending.
Authors: Nobusuke Hattori, Shinichi Nishida, Masahiro Hara, Sun Young Son
Abstract: This study is focused to the effects of plastic working on the fatigue strength of Ti-6Al-4V alloy with notch. In general, the fatigue strength of plastic worked specimen is higher than that of non-worked one. However, the potential of hardening ability of Ti-6Al-4V alloy is very limited. Accordingly, the effect of work hardening on fatigue strength about this material is very small. In addition, the surface of the worked part becomes rougher with increasing plastic deformed value and the fatigue cracks initiate at this part. Consequently, the fatigue limit of the plastic worked specimen is lower than that of the non-plastic-worked one.
Authors: Nobusuke Hattori, Shinichi Nishida, Priyo Tri Iswanto
Abstract: In order to study the effect of plastic working on fatigue strength of notched specimen, pulsating fatigue tests had been performed on notched deformed stainless steel specimens including on notched non-deformed specimens in order to evaluate the influence of mean stress on fatigue strength. The test results showed that the fatigue limits of plastic worked specimens are higher than that of non-worked one. This difference value would be caused by residual stress, work hardening and fiber texture due to plastic working. When degree of plastic deformation equal zero ("t=0), the fatigue limit ratio (σw /σB) of SUS430 is the higher than that of SUS304. On the other hand, the fatigue limit of worked specimen for SUS304 increases as the plastic deformation value increases to 0.5 mm and then it does not significantly increase from 0.5 mm to 1 mm. It is necessary to investigate an optimal deformation value.
Authors: Tomasz Cyryl Dyl, Robert Starosta
Abstract: Coatings of metal and ceramic composite were applied on the steel specimens using the subsonic process of flame spraying. The specimens were then subjected to both cold and hot plastic working by rolling and also cold pressing by the hydraulic press. Plastic working is an alternative to machining, as the method of finishing of coats applied by flame spraying. The article presents the findings of the research into the possibility of using plastic working (hot and cold rolling and pressing) to obtain the corrosion properties of the flame sprayed Ni-Al alloy coatings and Ni-Al-Al2O3 composite coatings. The alloy coatings had a single-phase structure, of the maximum 10% aluminium solubility in the crystal lattice of nickel, whereas in the composite coatings the volume content of non-metallic material Al2O3 was 15% and 30 %. After finishing the adhesion reduction, cracks on the surface and cross-sections of coatings was not observed. The largest value of strain hardening of alloy coating Ni-5%Al was stated after pressing. The composite coatings obtain by flame spraying be characterized by big surface roughness (Ra = 13.3 µm). The plastic working caused decrease surface roughness. Minimum value of Ra parameter was observed after hot rolling. It was found that maximal roughness was presented after pressing. The corrosion tests were performed in 0.01 M H2SO4 solution by potentiokinetic technique. The article presents the effect of dispersion phase of Al2O3 on corrosion properties of composite coatings on the nickel base. The corrosion rate was dependent on method of plastic working. The increasing drafts resulted in rise corrosion current density and decrease in value of corrosion potential.
Authors: Tomasz Cyryl Dyl, Robert Starosta, Robert Skoblik
Abstract: Modern materials on intermetallic matrix are in the scope of research of many scientific – research centers in Poland [1]. Intermetallic systematic alloys containing aluminium have high resistance to oxidation, abrasive corrosion and fatigue as well as heat resistance. That is why they are applied in the production of machine parts used in hard service conditions (internal combustion turbine blades, exhaust valves, turbo-blower rotors) [2]. Intermetallic coatings can be obtained by means of plasma spraying. Thermal spraying technology is widely used due to the possibility of increasing the service properties in surface layers (strength property, tribological, anti-corrosive and decorative property) as well as coating application on machine parts elements, on tools for plastic working (forging moulds busters, piston rods, gear wheels teeth, crank journals, valve seats, and combustion engine cylinders) [3, 4]. NiAl and Ni3Al coatings are characterized by high fatigue resistance, heat resistance and considerable corrosion resistance [5]. Coatings obtained by thermal spraying have high surface roughness. Thus, subsequent plastic treatment is advisable for plasma-sprayed intermetallic coatings. Therefore it is vital to define to what extent the change of unit pressure will influence reduction of surface roughness of intermetallic coatings. For this purpose experimental upsetting research was carried out on C45 steel samples having NiAl and Ni3Al coatings for the following unit pressures p = 500 MPa, p = 800 MPa, p = 1100 MPa.
Authors: Nobusuke Hattori, Kazuhiko Nakayama, Mian Zhang, Shinichi Nishida
Abstract: Nearly 90% of failures of machines and mechanical parts are caused at the area of stress concentrated in the structural components. Hence, it is important to investigate the method of improving fatigue strength for notched parts. In this paper, the fatigue tests have been performed to investigate the effect of the plastic-working on fatigue strength of specimens with notch. The main results obtained in this study are as follows: (1) The fatigue limit of notched specimen chamfered by the plastic-working increases by 45% than that of specimen without chamfer. (2) The reason of enhancing the fatigue strength may be to attributed to the work-hardening and compressive residual stress which suppress the fatigue crack initiation and propagation in early stage.
Authors: Yang Xiao, Masahiro Kuhara, Naoaki Noda, Kinjiro Saito, Masato Nagawa, Atsushi Yumoto, Ayako Ogasawara
Abstract: The bolts and nuts are widely used in various fields as important joining elements with long history. However, loosening induced by the vibration and external loads is still a big problem. And the loosening sometimes causes very serious accident without notice. This paper deals with a special stud bolt named “Super Stud Bolt (SSB)” which can prevent loosening effectively. There is a thin walled tube between the upper and lower threads, which can be deformed along the axial direction so that the phase difference is produced and SSB is developed. This phase difference induces the contrary force on the surfaces of the upper and lower threads, which brings out the anti-loosening performance. In this study, the processing and fastening-loosening courses are simulated with the finite element method. And the anti-loosening performance is analyzed and realized. In addition, the anti-loosening performances under various phase differences are compared and finally best dimensions for SSB are examined.
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