巻号一覧
78 巻, 3 号
選択された号の論文の9件中1～9を表示しています
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論説
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廣中 智久, 吉田 広明2007 年 78 巻 3 号 p. 199-205
発行日: 2007/07/26
公開日: 2008/01/26
ジャーナル フリーIn general, SF6 gas is widely used in order to protect the molten magnesium against oxidation. But SF6 gas is a typical green house gas being the source of global warming, so that the usage will be prohibited in near future. Ca is known to be effective for improving the oxidation resistance for magnesium alloy melts. However, it was reported that the addition of Ca would be resulted in the degradation of hot workability and mechanical properties. It is effective for the improvement of mechanical properties and formability to control the microstructure by controlled rolling process. The purpose of this study is the establishment of the technologies for controlled rolling process in Ca added magnesium alloys using isothermal rolling machine for suppression of edge cracks. In this study, the hot workability, recrystallization behavior and tensile properties after rolling of AZ61-xCa (x = 0∼0.45 mass%) was investigated. The results are as follows: 1.The addition of Ca was resulted in the significant degradation of hot workability because of the Al2Ca phase. The Al2Ca phase remained even after solution treatment at 698 K for 24 hr. 2.The recrystallization progression and grain growth rate of AZX610 alloys are obviously slower than that of steel. So multi-pass rolling with low reduction process can be effective to obtain fine microstructure without edge cracks. 3.Better in-plane isoropic ductility was obtained by texture control in controlled rolled AZX610 at 673 K compared with that of 573 K.抄録全体を表示PDF形式でダウンロード (614K) -
岡島 琢磨, 伊藤 樹一, 吉田 広明2007 年 78 巻 3 号 p. 207-214
発行日: 2007/07/26
公開日: 2008/01/26
ジャーナル フリーRecently, a warm forging process is remarkable from the points of view in near net shaping and abolishment of additional heat treatment by micro-structural controlling. In generally, a die life in forging decreases accompany with the increase of forging temperature. The die life in hot forging is only about 1/10∼1/100 compared with that in cold forging, because of the serious heat damage. The die life in warm forging is normally about same level of that of hot forging in spite that it is estimated to be about 3∼10 times longer than that in hot forging. There are many important factors such as cooling, lubrication, tool material with high strength and heat resistance, surface treatment, so it is difficult to find out the optimal combination. To solve the above mention problems, we have developed the new Punch Damage Test using parts former for warm forging by use of FE analysis. In this study, we investigated the effects of surface treatments and the kinds of tool steels on die damage in warm forging by the developed Punch Damage Test. And we tried to clarify the mechanism of the die damage by use of FE analysis. The obtained results are following. 1. The wear depends on the depth of plastic flow in hot forging. In order to decrease the wear, it is important to increase of the yield strength of tool steel at elevated temperature, and to apply the surface treatment with high heat resistance. 2. The length and the number of heat cracks increase by applying hard coating, on the other hand hard coating can decrease the length of crack because of defensible boundary between hard coating and base steel. 3. The developed Punch Damage Test is very effective for the evaluation of hard coatings and tool steels in warm forging.抄録全体を表示PDF形式でダウンロード (508K) -
八田 武士, 廣中 智久, 吉田 広明, 五十川 幸宏, 益永 敦郎2007 年 78 巻 3 号 p. 215-223
発行日: 2007/07/26
公開日: 2008/01/26
ジャーナル フリーINCOLEL alloy 718(IN718) has been used for important components such as gas turbine disk and jet engine shaft, and the amount of the usage are increasing. As for gas turbine disk, the demand of reliability has been getting stronger. One of the most effective methods to improve the reliability is grain refinement giving the increase of low fatigue strength and toghness. In order to refine the micro-structure of IN718, the only method is recrystarization at lower temperature in forging because of single-phase material. To obtain the forged components having fine micro-structure, forging temperature, strain and their distribution must be controled precisely. Process modelling using FE analysis is very effective to design optimal forging processes to obtain the target micro-structure and mechanical properties of the components. We have originally developed the digital engineering system named DAINUS composed of 4 prediction modules, which are (1)damage prediction module, (2)micro-structural prediction module, (3)die damege prediction module, (4)cavity consolidation prediction module. In this work, we have developed micro-structural prediction data base and system for IN718. Micro-structural prediction under multiple recrystallization and partial recrystallization condition is very difficult to obtain sufficient accuracy. Moreover the it's system in incremental free forging is also difficult, because of the rapid increase and decrease of the temperature, strong strain distribution, occurrence of additional recrystallization by repeated forging during partial recrystallization. In this paper, to solve these problems we have developed new micro-structural prediction system of IN718 by the following approaches, (1)establishment of the precise recrystallization data base in wide temperature range, (2)establishment of the incremental method corresponding to rapid temperature and strain change, (3)development of new averaging method. By these new approaches, we could obtain enough prediction accuracy even in incremental forging of gas turbine disk.抄録全体を表示PDF形式でダウンロード (711K) -
深谷 輝雄, 伊藤 樹一, 吉田 広明2007 年 78 巻 3 号 p. 225-232
発行日: 2007/07/26
公開日: 2008/01/26
ジャーナル フリーRecently the demands of a performance and environmental treatment for forging lubricant oil have been getting stronger. Especially, in the warm forging which is spread gradually for the purpose of near net shaping or complex shaping, the environmental problem is considerable. Concerning to the lubricant performances of the oil, both of the high lubrication and cooling abilities are required in warm forging. As for the environmental treatment, the harmful gas and sharp smell must be reduced as much as possible. We have developed the new oil contained overbased calcium sulfonate for warm forging to be satisfied with the needs. The results are follows. 1. The smell was much reduced even at 800 ℃ comparison to conventional high performance forging oil which contains Zn-DTP. 2. The forging load decreased about 35 % at 800 ℃ in backward extrusion. 3. The depth of punch wear was reduced about 14 % after 5000 shots.抄録全体を表示PDF形式でダウンロード (512K)
解説
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篠塚 淳2007 年 78 巻 3 号 p. 233-240
発行日: 2007/07/26
公開日: 2008/01/26
ジャーナル フリーRecent remarkable advancement of computer performances made possible a metal cutting simulation with finite element analysis. Nowadays, commercial 3D-FEA software specialized in machining processes, such as turning, milling and drilling, is available. This review focuses on a predictability of FEM cutting simulations. Detailed material properties, such as flow stress under high stain rates and high temperatures conditions, friction at tool-chip contact region, thermal conductivity and heat capacity, are indispensable to simulate a metal cutting process in detail. Flow stress characteristics proposed so far, a nonlinear friction property at the tool-chip contact region and equations to estimate tool wear and tool breakage are presented. A prediction of chip controllability with a FEA is shown. Next, a dynamic thermo elasto-plastic FEM cutting simulation is shown. Deformations and temperatures were solved explicitly in the FEA. A penalty force and a correction heat flux that can be adapted to a wide range of cutting condition were considered at the tool-chip contact region in the FEA. Finally, some results of the FEA under ultra high-speed cutting conditions that cutting speed exceeds the plastic wave speeds of a workpiece material are shown as one of examples indicating high predictability of the FEA.抄録全体を表示PDF形式でダウンロード (581K) -
中村 隆2007 年 78 巻 3 号 p. 241-248
発行日: 2007/07/26
公開日: 2008/01/26
ジャーナル フリーOn basis of chip formation mechanisms, tribology in cutting processes is described summarily in this review. Contacting pressure on a tool surface is extremely high and the contacting surface is fresh in the cutting processes. So, friction in the cutting is classified on a severe category in tribology field. Functions of cutting fluid are surveyed on shearing area, rake face friction area and flank friction area respectively, where cutting energy is converted into heat. Environmental measures of the cutting fluid are introduced and experimental results of a new technology are explained from the viewpoint of cooling ability. Finally, experimental tests, which can simulate the rake face friction, are introduced and effects of cutting temperature and surface roughness of the rake face on the lubrication ability are discussed on the basis of the experimental results.抄録全体を表示PDF形式でダウンロード (483K) -
五十川 幸宏, 伊藤 樹一2007 年 78 巻 3 号 p. 249-258
発行日: 2007/07/26
公開日: 2008/01/26
ジャーナル フリーThe forging has the following features compared with other metal working methods. 1. The surface expansion ratio at the forging is extremely large. 2. The normal pressure at the forging is extremely large. 3. The supply of the lubricant at the forging is difficult. The tribo-simulator for the forging that can take out only the friction energy that shows the feature between the tool and the work of the forging process described now is desired. In this explanation, the behavior of the surface expansion ratio and the normal pressure change in a basic deformation behavior at the forging is summarized. The feature of the tribo-simulator for the forging that has been proposed so far and the result achieved by it are shown, and the way it should be of the tribo-simulator in the future is described.抄録全体を表示PDF形式でダウンロード (516K) -
藤原 正尚, 吉田 広明, 五十川 幸宏2007 年 78 巻 3 号 p. 259-265
発行日: 2007/07/26
公開日: 2008/01/26
ジャーナル フリーThermo-mechanical controlled processing (TMCP) for rolling has been developed to obtain high strength and toughness even at low temperature for plate, and there are many applications as real production. In case of forging, there were a few example applied TMCP. For automobile forged components, weight reduction is one of the most effective methods to reduce fuel consumption for decreasing the global warming. By the application of TMCP for forging process, named as controlled forging, the mechanical properties of forged components are extremely improved so that it can lead weight reduction. In this paper, the mechanical properties of controlled forged steels and some application for real production are introduced.抄録全体を表示PDF形式でダウンロード (788K)
技術資料
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吉田 広明, 岡島 琢磨, 八田 武士, 藤原 正尚, 伊藤 樹一2007 年 78 巻 3 号 p. 267-274
発行日: 2007/06/04
公開日: 2008/01/26
ジャーナル フリーRecently CAE(computer aided engineering) has been spread widely in metal forming. Large model calculation and remeshing in heavy deformation by FE analysis become possible because of the improvements of hardware and software. However the obtained outputs in FE analysis are limited in shape, temperature, various stress and strain. So it is difficult to design optimal process to obtain a final target properties in quantitatively by the current FE analysis system. We have developed digital engineering system DAINUS(DAIdo NUmerical process engineering System) consists of 4 prediction module (1)DAINUS-damage, (2)DAINUS-grain, (3)DAINUS-life, (4)DAINUS-cavity. DAINUS is installed in commercial FE analysis code using user subroutine, and can predict a ductile fracture by DAINUS-damage, micro-structure and mechanical properties by DAINUS-grain, die life by DAINUS-life, cavity consolidation by DAINUS-cavity. Nearly all kind of information in metal forming can be obtained in concretely and in quantitatively by DAINUS. In this paper, the features and abilities are introduced.抄録全体を表示PDF形式でダウンロード (619K)
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