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| 1.
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論文
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上田, 隆司 ; 金曽, 久佳 ; 松森, 昇 ; 杉田, 忠彰
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| 2.
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論文
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上田, 隆司 ; 金曽, 久佳 ; 大野, 誉洋 ; 杉田, 忠彰
概要:
Influence of the grain size of diamond stone on the superfinishing performances is investigated experimentally. The mechanism of chip formation is investigated by observing the shape of chips and the finished surfaces of workpiece with
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scanning electron microscope. The work materials used are alumina (Al2O3), silicon carbide (SiC), silicon nitride (Si3N4) and zirconia (ZrO2), which are sintered under the atmospheric pressure, and Mn-Zn ferrite, which is sintered under HIP. The grain size of stone is changed from # 500 to # 8 000. The results are as follows. The diamond stone with suitable bonding strength makes it possible to remove the work material as chips even if its grain size is finer than # 1 000. Two types of chips are obserbed; one is the crack-type chips which are made by brittle fracture, and the other is the flow-type chips which are made by plastic deformation. As the grain size of stone becomes smaller, the shape of chips changes from crack-type to flow-type. The critical grain size is dependent on the work materials and it becomes smaller in the order of ZrO2, Mn-Zn ferrite, Al2O3, Si3N4 and SiC. The condition of making the flow-type chips is important to obtain the mirror surface of ceramics.
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| 3.
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論文
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上田, 隆司 ; 坂本, 智 ; 杉田, 忠彰
概要:
In order to simplify the treatment of coolant in production systems, the superfinishing characteristics under the condition of water-solution type coolant are investigated experimentally. This type of coolant is inferior to an
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oil type coolant in removing chips from the stone because of its poor permeability. Electrolytic in-process dressing is applied to promote the self-dressing of diamond stone. As work materials, alumina which is sintered under atmospheric pressure and soft steel (equivalent to 0.15% carbon steel) are used. The results obtained are as follows. Electrolytic in-process dressing makes it possible to use the coolant of water-solution in superfinishing. The suitable conditions in electrolytic in-process dressing depend on the machinability of work materials. The soft steel whose chips are easy to make a loading on the working surface of stone needs the stronger dressing. A concentration of some percent is sufficient for a coolant to maintain its essential properties. The electrolytic in-process dressing is more effective for harder or finer stone, because it can control the cutting ability of the stone.
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| 4.
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論文
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上田, 隆司 ; 坂本, 智 ; 杉田, 忠彰
概要:
A new method of the superfinishing is investigated, in which the cutting ability of diamond stone is controlled by changing the strength of electrolytic in-process dressing. Water-solution type coolant and metal bonded stone are used
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to employ the electrolytic dressing. As work materials, a carbon steel S 45 C, a bearing steel SUJ 2 and alumina are used. The results obtained are as follows. It is effective for control of electrolytic dressing to change the operating time of electrolysis or the ratio of on-time to off-time in electric pulse. As the dressing becomes stronger, the cutting ability of stone improves and the metal removal rate becomes larger. As the dressing becomes weaker, the cutting ability of stone is lost and then the surface roughness of workpiece becomes smaller. The cutting ability of stone which has been lost in finishing operation can be regenerated again applying the strong electrolysis. This in-process dressing method makes it possible to obtain the intended finishing performances of metal removal rate and surface roughness, and to finish several work materials of different machinability using a same kind of stone.
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