巻号一覧
71 巻, 2 号
選択された号の論文の8件中1～8を表示しています
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論説
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倉田 征児, 松田 幸紀2000 年 71 巻 2 号 p. 111-118
発行日: 2001/02/28
公開日: 2001/02/28
ジャーナル フリーIn order to improve the machinability of high hardness cold work die steel such as 50HRC, the influence of sulfur and calcium has been investigated. Tool wear and cutting force are smaller by the complex addition of these two elements than by single addition of sulfur. Namely, these two additives improve the machinability of high hardness steels. In case of high hardness steel, cutting temperature becomes higher than in annealed steel. Consequently, build-up-edge disappears and manganese sulfides easily adhere to the surface of tools and this adhered sulfides play a role as lubricant. It is concluded, therefore, sulfur and calcium complex addition increases the amount of adhered manganese-sulfides and improves machinability by lubricating effect.抄録全体を表示PDF形式でダウンロード (766K) -
藤井 利光, 松田 幸紀2000 年 71 巻 2 号 p. 119-129
発行日: 2001/02/28
公開日: 2001/02/28
ジャーナル フリーThis study has been carried out to clarify the effect of Si content on machinability of 5%Cr-3%Mo type hot working die steel hardened and tempered to 49HRC. The results are as follows.
(1) Carbides retained in hardened and tempered specimens are M6C and MC and the amount of these carbides decrease with the decrease in Si content.
(2) In end-milling, carbide tools exhibit shorter life with decreasing Si content, especially at the range of Si content less than 0.3%. Adhesive wear increases with the decrease in Si content.
(3) In turning by carbide tools, the cutting forces and temperatures rise with decreasing Si content.
(4) High speed tensile test at elevated temperatures reveals that the steels with lower Si content show higher maximum flow stress and larger reduction of area.
(5) By the calculation of turning-cutting forces based on the two-dimensional cutting model, it is found that the decrease in Si content raises the shear stress resulting in the increase of cutting forces. The high shear stress of lower Si steels is considered due to their high strength at elevated temperature.抄録全体を表示PDF形式でダウンロード (628K) -
尾崎 公造, 瓜田 龍実, 古賀 久善, 合屋 純一2000 年 71 巻 2 号 p. 131-139
発行日: 2001/02/28
公開日: 2001/02/28
ジャーナル フリーRecently, induction heating treatments have been applied to high alloy tool steels, for example JIS-SKH51. In rapid and short time heating, however, the influence of heating time and temperature on carbide dissolution and hardness is not fully clarified. The purpose of this study is to make clear the influence of these two factors on carbide dissolution and quenching-tempering hardness behavior of JIS-SKH51. Results obtained are as follows;
1) The initial stage of the holding at hardening temperature is characterized by the dissolution of small M6C carbides.
2) Increase of carbon and alloy elements in matrix before induction heating contributes to the increase in hardness in short time heating.
3) Finally, we applied induction hardening to two sizes of SKH51 forming rolls using the fundamental knowledge obtained in this study. Surface hardness higher than 65HRC and satisfactory hardened depth for each size of rolls were obtained.抄録全体を表示PDF形式でダウンロード (530K) -
松田 幸紀, 坂本 良昭2000 年 71 巻 2 号 p. 141-148
発行日: 2001/02/28
公開日: 2001/02/28
ジャーナル フリーThe elapsed dimensional change characteristics of 1C-8Cr cold work die steel were studied by considering tempering temperature and subzero treatment. Elapsed dimensional change becomes extremely large when tempered at higher than 773K compared with low temperature tempering. It is caused by the chemical instability and increased strain of retained austenite derived from martensitic transformation after high temperature tempering. To decrease elapsed dimensional change while keeping the high hardness at high temperature tempering, it is effective to add the stabilizing treatment: additional tempering at 625K to 753K. Subzero treatment, however, can not work effectively to suppress dimensional change, and also requires the stabilizing treatment. The mechanism to prevent this dimensional change is discussed from a view point of stabilizing behavior of small amount of retained austenite.抄録全体を表示PDF形式でダウンロード (229K)
解説
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福井 雅彦2000 年 71 巻 2 号 p. 149-156
発行日: 2001/02/28
公開日: 2001/02/28
ジャーナル フリーRecently, production of different products in different quantities is becoming possible. And die-making technologies which contribute to drastic reduction of production time has widely attracted attention. One of such mainstream technologies is the "Polishless cutting method" which leads to "Finish-less process". In this paper, the problems in realizing highly efficient polishless cutting using high speed milling and cutting machine are discussed: CAM data accuracy, spindle viscosity of high speed milling machine, etc. Future developments are, furthermore, expected for items such as new linear driving method, high precision-high speed milling machine with ten times higher accuracy, and CAM system which enables to make NC data automatically in order to keep the cutting force constant.抄録全体を表示PDF形式でダウンロード (747K) -
－金型製造工期短縮を中心に－並木 邦夫2000 年 71 巻 2 号 p. 157-165
発行日: 2001/02/28
公開日: 2001/02/28
ジャーナル フリーDie and mold industries make up the base of Japanese key industries such as automobile and electric appliance. In the turbulent era when price slashing, globalization, and information revolution are progressing at increasingly faster rates, "production cost cutting" and "shorter delivery times" are top priority. To reduce the delivery times in die and mold production process, three points are to be considered: shortening design hours, simplifying process and shortening each process times. Referring to the trend of up-date die making technologies, new tool steels are introduced. Pre-hardened steels, free machining steels and easy to repair weld steels are contributing to the process time saving. Technical software on application technology also works for shorter delivery times. Software covering from die material selection to process simulation will be widely and practically used in the future. New tool steels and application technologies for precise die and molds are also mentioned in this article.抄録全体を表示PDF形式でダウンロード (216K)
技術資料
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柳澤 民樹, 須藤 興一, 中川 勝2000 年 71 巻 2 号 p. 167-170
発行日: 2001/02/28
公開日: 2001/02/28
ジャーナル フリーWhen heat treating hot working dies, it is important to harden with high cooling rate to obtain high toughness without distortion. These two, high toughness and small distortion, are competing each other and difficult to be obtained at the same time. The heat treatment process has been newly developed under the name of AHIT process: Amister High Impact Value Treatment. This process is based on three fundamental concepts: to prevent carbides precipitation along grain boundaries at high temperature, to make die internal temperature distribution uniform in the middle temperature region and to suppress Bainitic transformation. The distortion of the dies processed by AHIT is almost one half the one of blow quenched ones. And the toughness is 1.7to 2 times higher than conventionally heat treated ones, which results in improved heat check resistance. AHIT process has established 40% reduction in finish machining time after heat treatment due to small distortion.抄録全体を表示PDF形式でダウンロード (165K) -
太田 久司, 倉田 征児, 並木 邦夫2000 年 71 巻 2 号 p. 171-174
発行日: 2001/02/28
公開日: 2001/02/28
ジャーナル フリーIn these days, user's demands in die and mold production has been drastically diversified. Daido Steel has newly developed 50HRC type pre-hardened cold work tool steel, CX1, in accordance with the strong demands for shorter delivery times and cost cutting. CX1 shows higher hardness than conventional pre-hardened steels with 40HRC, which is realized by alloy and microstructure designing. CX1 is directly finish machined after rough machining without heat treatment, which results in shorter delivery times. Distortion free quality contributes to the shortening of finish process time, especially. CX1 exhibits the same mechanical properties as those of other cold work tool steels of the same hardness and shows almost the same face and end-milling machinabilities as conventional pre-hardened grades. Although there are some difficulties in drilling and tapping due to high hardness, the selection of tool and cutting conditions make machining efficiency to mass production level. This grade has just been practically used for cold work dies and tooling parts and it is expected to expand to wide variety applications.抄録全体を表示PDF形式でダウンロード (579K)
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