電位器接線片沖壓工藝與模具設(shè)計(jì)【含圖紙】

喜歡就充值下載吧。資源目錄里展示的全都有，下載后全都有請(qǐng)放心下載，原稿可自行編輯修改=【QQ：1304139763可咨詢交流】喜歡就充值下載吧。喜歡就充值下載吧。資源目錄里展示的全都有，下載后全都有請(qǐng)放心下載，原稿可自行編輯修改=【QQ：1304139763可咨詢交流】喜歡就充值下載吧。喜歡就充值下載吧。資源目錄里展示的全都有，下載后全都有請(qǐng)放心下載，原稿可自行編輯修改=【QQ：1304139763可咨詢交流】喜歡就充值下載吧。 Sheet metal forming of magnesium wrought magnesium wrought alloys formabilityand process technologyAbstractNew developments at the for Metal Forming and Metal Forming Machine Tools show that magnesium sheets possess excellent forming behavior, if the process is conducted at elevated temperatures. For the evaluation of mechanical properties relevant for forming of magnesium sheets, uni axial tensile tests have been carried out at various temperatures and strain rates.Deep drawing tests with magnesium alloys AZ31B, AZ61B, and M1 show very good formability in a temperature range between 200 and2508C. Besides temperature, the influence of forming speed on limit drawing ratio has been investigated. The obtained results lead to the conclusion that it is possible to substitute conventional aluminum and steel sheets by using magnesium sheet metal wrought alloys.1. IntroductionIn order to reduce fuel consumption, general efforts have been made to decrease the weight of automobile constructions by an increased use of lightweight materials. In this framework, magnesium alloys are of special interest because of their low density of 1.74 g/cm3.Presently, magnesium alloys for the use as automobile parts are mainly processed by die casting. The die casting technology allows the manufacturing of parts with complex geometry. However, the mechanical properties of these parts often do not meet the requirements concerning the mechanical properties (e.g. endurance strength and ductility). A promising alternative has to be seen in components that are manufactured by forming processes. The parts manufactured by this technology are characterized by advantageous mechanical properties and fine-grained microstructure without pores 1. However, a widespread use of forming technologies for the processing of magnesium alloys is restricted because of insufficient knowledge about the forming technologies and suitable process parameters that have to be applied 2,3.Automotive body constructions offer a great potential for the application of magnesium sheet metal components.In general, the automotive body completely consists of sheet metal parts and represents a share of about 25% of the entire vehicle mass. Therefore, the substitution of conventional sheet materials by magnesium sheets would lead to essential weight savings in this application.2. Plastic material properties of magnesium sheetsMagnesium alloys show a limited formability at room temperature. This results from the fact that the hexagonal crystal structure and the low tendency to twinning only allow limited deformations. The differently orientated crystallites only show a deformation on the individual base slip plane, which leads to a mutual slip hindrance 4, 5. A considerable improvement of the forming qualities can be achieved by applying temperature. The considerable increase in formability that occurs in the temperature range from 200 to2258C (depending on alloying composition) was investigated by Siebel 6. The reason for this effect was found in the thermal activation of pyramid sliding planes in the hexagonal structure 7. 2.1. Influence of forming temperature on flow stressA detailed evaluation of the deformation properties of magnesium sheets requires the determination of the materials characteristic values like anisotropy or flow curves 8, 9. Because systematic investigations in this area are not available, extensive investigations concerning the influence of temperature and strain rate on plastic properties of various magnesium alloys were performed at Institute for Metal Forming and Metal Forming Machine Tools (IFUM). Fig. 1 displays flow curves of magnesium sheet material AZ31B at different temperatures, determined in the uniaxial tensile test according to EN 10002, part 5.It is obvious that the stresses and possible strains largely depend on the forming temperature. The decrease of flow stresses in the temperature range above 2008C attributes to temperature-dependent relaxation. 3. Deep drawing of magnesium alloysIn order to investigate the formability of magnesium sheets, deep drawing tests at different forming temperatures were carried out at IFUM with a cylindrical tool system.Fig. 3 shows the results of deep drawing tests at a temperature of 50C. Whereas the deep drawing of the alloy AZ31B using a low drawing ratio of b0 1:45 was possible (drawing depth: 30 mm), the alloys AZ61B and M1 showed early fracture. Using drawing ratio of b0 1:6, AZ31B showed fracture similar to AZ61B and M1. These tests confirm the low formability of magnesium alloys at low temperature. However, the investigated magnesium alloys show very good formability at higher temperature ，The maximum limit drawing ratio of b0 ; max 2:52 was detected for AZ31B at a forming temperature of 2008C. AZ61B and M1 show maximum values of approximately b0 ; max 2:20 up to2.25. The values of the aluminum alloy AlMg4.5Mn0.4 are displayed for comparison. Due to the good formability of the aluminum alloy at room temperature, the increase in limit drawing ratio with rising temperature is low compared to the magnesium alloys.The results gained from the tensile tests showed the significant influence of strain rate on the mechanical properties of magnesium alloys. 1 H. Kehler et al., Partikelverstarkte Leichtmetalle, Metall Band, 49,Heft 3, 1995.2 E. Doege, K. Droder, St. Janssen, Leichtbau mit Magnesiumknetlegierungen Blechumformung und Prazisionsschmieden TechnischerMg-Legierungen, Werkstattstechnik, Band 88, Heft 11/12,1998.3 E. Doege, K. Droder, F.P. Hamm, Sheet Metal Forming ofMagnesium Alloys, Proceedings of the IMA-Conference on MagnesiumMetallurgy, Clermont-Ferrand, France, October 1996.4 H.J. Bargel, G. Schulze, Werkstoffkunde, VDI-Verlag GmbH,Dusseldorf, 1988.5 C.S. Roberts, Magnesium and Its Alloys, Wiley, New York, 1960.6 G. Siebel, in: Beck (Ed.), Technology of Magnesium and Its Alloys,Hughes, London, 1940.7 N.N.: Magnesium and Magnesium Alloys, Ullmanns Encyclopediaof Industrial Chemistry, Reprint of Articles from 5th Edition, VCH,Weinheim, 1990.8 E. Doege, K. Droder, Processing of magnesium sheet metals by deepdrawing and stretch forming, Mat. Tech. 78 (1997) 1923.9 E. Doege, K. Droder, St. Janssen, Umformen von Magnesiumwerkstoffen,DGM-Fortbildungsseminar, Clausthal-Zellerfeld, Oktober1998, pp. 2830.10 L. Taylor, H.E. Boyer, in: E.A. Durand, et al. (Eds.), MetalsHandbook, 8th Edition, Vol. 4, American Society of Metals,ol. 4, American Society of Metals,Cleveland, OH, 1969.11 K. Siegert, et al., Superplastische Aluminiumbleche Verarbeitungmit numerischen Pressen, Metall, 45 Jahrgang, Heft 4, 1991.12 E.F. Emley, Principles of Magnesium Technology, Pergamon Press,Oxford, 1966.13 D. Schmoeckel, Temperaturgefuhrte Prozesteuerung beim Umformenvon Aluminiumblechen, EFB-Forschungsbericht, Nr. 55, 1994.14 H. Beiwanger, Warmziehen von Leichtmetallblechen, Mitteilungder Forschungsgesellschaft Blechverarbeitung, Nr. 27, 1950. 15 E. Kursetz, Die Anwendung von Warme bei der Herstellung vonBlechformteilen aus Schwer Umformbaren Werkstoffen, BanderBleche Rohre, Nr. 5, 1974.16 O. Heuel, Optimierung der Werkzeugtemperatur Durch RichtigeAuslegung und Installation der Temperiersysteme, Der Stahlformenbauer,Heft 1, 1992.5