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Volume 44, Issue 9
Displaying 1-9 of 9 articles from this issue
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Minobu SUKIMOTO, Yuichi TAGUCHI, Masashi SAKAGUCHI, Hitoshi AKIYOSHI, ...1994 Volume 44 Issue 9 Pages 475-479
Published: September 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSIt is important in tube bending to prevent both decrease in the tube strength by the reduction of its outer thickness and decrease in its cross sectional area by the flattening of the tube. The effect of the bending conditions such as the pressure of clamp die, pressure die, booster, the booster speed and bending speed on changes in the thickness and the degree of flatness of tubes bended by a rotary draw bender was investigated using A6063 alloy tubes. It was found that the effect of the booster speed was biggest and the effects of pressure of the pressure die and the bending speed were small, and then that the pressure of the clamp die and the booster had no effect. In order to gain the little decrease of the outer thickness and the degree of flatness of the bended tubes, the pressure of the pressure die, the booster speed and the bending speed have to be low, fast and slow, respectively. These are related to the decrease of axial tension in tube bending.View full abstractDownload PDF (2647K) -
Hisashi NISHIMURA, Takeshi SATO, Hirokuni YAMAMOTO1994 Volume 44 Issue 9 Pages 480-485
Published: September 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSSuperplastic Zn-Al alloy matrix composites reinforced with SiC particles of 20μm in diameter were produced by the hot-press process. The plastic forming of these composites was performed in a hydraulic bulging system. After bulging, the test piece was checked by the scanning electron microscopy (SEM). After superplastic forming, cavitation is observed at the interface between the matrix and SiC particles as well as at regions of agglomeration of SiC particles. On the test piece deformed without back pressure, cavitation occurs at the convex surface, especially around the top. The back pressure is confirmed to have the effect to reduce cavitation by the SEM exhibits observation. The test piece deformed at 2.5MPa back pressure an improved bulging limit by about 19% compared with the case of without back pressure. To employ back pressure in the deformation process is effect both to suppress the strain localization and to produce uniform strain distribution. The application of 2.5MPa back pressure in bulging, results in the increased fracture strength of composites at 250°C by about 22%. The high temperature strength becomes increased by the heat treatment to negate superplasticity after bulging.View full abstractDownload PDF (3073K) -
Makoto OGAWA, Mitsuru INOSE, Minoru ARAI, Tsuneo SAGA1994 Volume 44 Issue 9 Pages 486-491
Published: September 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe cutting performance in the micro drilling of a 5056 wrought aluminum alloy has been studied in terms of the chip shape produced, the record of cutting torque and thrust in drilling and the surface finish of a hole. The chip forms are conical helical chip in drilling of the shallow hole, and helical chip with long pitch having a large crack at inside-edge of a chip in drilling of a relatively deep hole. The helical chip with long pitch can easily flow out of a hole through the flutes of a drill. As a result, the cutting torque and thrust do not increase extremely even when the hole is deep. This tendency becomes remarkable especially with the decreased diameter of a micro drill because of the increased effective rake angle at the inner side of the cutting edge. The increased web thickness and point angle of a drill easily produce the helical chip with long pitch, and result in the markedly improved drilling performance such as facilitate chip flow, reduced cutting force and increased critical feed rate for the drill failure.View full abstractDownload PDF (3029K) -
Masahiro YANAGAWA1994 Volume 44 Issue 9 Pages 492-497
Published: September 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSInfluence of grain size and Mg content on the ductility of Al-Mg alloys at 77, 173 and 300K has been investigated. As the grain size increased from 20 to 300μm, the uniform elongation at 77 and 173K reached maxima when grain size was 40μm. On the other hand, at 300K, the uniform elongation increased monotonously with increasing grain size. The local elongation at 300K was nearly constant (3%) regardless of grain size and Mg content, while at 77 and 173K the local elongation increased with decreasing grain size or Mg content and exceeded 10% at 77K when grain size was 20μm. Fractographic observations revealed that the area fraction of intergranular fracture at 77K increased with increasing grain size or Mg content. On the other hand, intergranular fracture was not observed at 177 and 300K regardless of grain size and Mg content. The dependence of elongation upon grain size and Mg content at 77K was explained mainly by the intergranular fracture. Grain size dependence of elongation at 173 and 300K was well explained by the change in both the strain-hardenability and the occurrence of the nonuniform deformation caused by the serrated yielding or the decreased characteristics of the polycrystalline.View full abstractDownload PDF (3154K) -
Toshio HAGA, Mitsugu MOTOMURA, Arman MUNAF, Shinsuke SUZUKI1994 Volume 44 Issue 9 Pages 498-503
Published: September 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSTo produce sound free solidification surface of the strip, melt drag process, which is one of single roll processes, was improved. An additional roll (forming roll) was attached to the outer side of the nozzle of the original melt drag process. In this work, forming of the free solidification surface of the strip was applied at the semi-solid phase by the forming roll. Free solidification surface can be formed in the smooth and flat shape, and thickness distribution of the cross section becomes uniform. The strip with 0.5 to 1.5mm thickness can be cast. Roll speed of this process is as fast as that of the original melt drag process (20-70m/min). The semi-solid region is formed by a roll and the forming load is very low, thus, the strip does not stick to the roll. Formability of the free solidification surface depends on the flow stress at the semi-solid phase.View full abstractDownload PDF (4323K) -
Tatsuya OHMI, Kouki MINOGUCHI, Masayuki KUDOH, Youichi ITOH, Kiyotaka ...1994 Volume 44 Issue 9 Pages 504-509
Published: September 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSA semi-solid slurry of a hypereutectic Al-Si alloy containing fine primary silicon crystals is producible by "slurry-melt mixing (SMM)" process. In the SMM process, a melt of a phosphorus-added hypereutectic Al-Si alloy (second-alloy melt) is mixed with a semi-solid slurry of a hypoeutectic Al-Si alloy (first-alloy slurry) which has been solidified with stirring in a furnace-cooled vessel. In this study, the change in apparent viscosity of the stirred slurry, whose silicon content changed from 8 to 20mass% by mixing of molten Al-32mass%Si alloy, was measured continuously during the SMM process. Immediately after the mixing of the second-alloy melt, the apparent viscosity decreases drastically from 7 to about 0 Pa•s. This abrupt change is attributed to the following facts: (1) The primary alpha-phase which has been crystallized in the first alloy remelts rapidly in the mixed alloy. (2) The fraction of the primary silicon in the mixed alloy is lower than that of the primary alpha-phase in the first alloy, though there is a strong driving force of crystallization of the primary silicon in the mixed alloy in comparison with the conventionally solidified Al-20mass%Si alloy. (3) The apparent viscosity of the hypereutectic alloy is similar in order of magnitude to that of the hypoeutectic alloy of the same fraction solid.View full abstractDownload PDF (4078K) -
Mamoru MATSUO1994 Volume 44 Issue 9 Pages 510-525
Published: September 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (11450K) -
Mituso NIINOMI1994 Volume 44 Issue 9 Pages 526-527
Published: September 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (239K) -
Norio FURUSHIRO1994 Volume 44 Issue 9 Pages 528-529
Published: September 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (235K)
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