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| 1.
論文 |
論文
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Tatsuno, Daichi ; Yoneyama, Takeshi ; Kawamoto, Kiichiro ; Okamoto, Masayuki ; 立野, 大地 ; 米山, 猛
概要:
To build a processing method for textile carbon fiber reinforced thermoplastic (CFRTP) sheets, a production system to fo
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rm, cut, and join the sheets by using a mechanical servo press machine was developed and examined. The system's problems were analyzed, and attempts were made to solve them through a series of processes. In press forming, the effects of sheet geometry, fiber orientation, and slide motion on the forming of the variant-cross-sectional-beam, which has a narrow and wide part, were investigated. In addition, the shear-cutting method was chosen trimming the unnecessary region of the variant-cross-sectional-beam. For the joining process, a thermal welding method that uses a heating-plate was chosen. The closed-sectional-beam was fabricated by thermally welding a pair of the variant-cross-sectional-beams. Finally, the potential of the production system for textile CFRTP sheets using the mechanical servo press machine was discussed. © 2016 The Authors Polymer Composites published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.<br />Embargo Period 12 months
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| 2.
学位論文 |
学位
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河本, 基一郎 ; Kawamoto, Kiichiro
概要:
博士論文本文Full 以下に掲載：International Journal of Automation Technology 9(2) pp.184-192 2015. Fuji Technology Press Ltd. 共著者：Kiichiro Kawamoto, Takeshi Yoneyama, Masato Okada
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学位論文 |
学位
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河本, 基一郎 ; Kawamoto, Kiichiro
概要:
博士論文要旨Abstract 以下に掲載：International Journal of Automation Technology 9(2) pp.184-192 2015. Fuji Technology Press Ltd. 共著者：Kiichiro Kawamoto, Takeshi Yoneyama, Masato Okada
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論文 |
論文
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Kawamoto, Kiichiro ; Yoneyama, Takeshi ; Okada, Masato ; Kitayama, Satoshi ; Chikahisa, Junpei
概要:
This study focused on utilizing a servo die cushion (in conjunction with a servo press) as a "back-pressure load generator," to determine its effect on shape accuracy of the formed part and total forming load in forward extrusion during
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cold forging. The effect of back-pressure load application was confirmed in experiments, and the optimum setting pattern of back-pressure load was considered to minimize both shape accuracy of the formed part and back-pressure energy, which was representative of forming energy using a sequential approximate optimization. The precise back-pressure load control by the servo die cushion enabled the ideal load-pattern setting for optimization to be achieved.
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| 5.
論文 |
論文
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Yoneyama, Takeshi ; Tatsuno, Daichi ; Kawamoto, Kiichiro ; Okamoto, Masayuki
概要:
Carbon-fiber-reinforced thermoplastic (CFRTP) is viewed as a prospective material for high-cycle production of CFRP part
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s. This paper deals with a process whereby a preheated thermoplastic plain-woven carbon fiber fabric sheet is formed into a circular cup by a mechanical servo-press. The effects of press parameters, specifically the bottom dead center and slide speed in the forming of CFRTP cup, on the press load, pressure, internal temperature, shape accuracy, and internal structure have been investigated. A plain-woven carbon-fiber-reinforced PA6 thermoplastic sheet was used. The sheet consisted of four layers of woven 3K carbon and had a thickness of 1 mm. The sheet was heated to 320°C under a halogen heater so that it would be around the recommended temperature for forming 260°C after transfer to the mold. The sheet was pressed into a circular cup shape by a cold mold while the periphery was cramped by a heated holder so as not to cool the sheet before it was pulled into the mold cave. Die clearance was designed considering the thickness increase due to the fiber concentration during the forming. By increasing the slide stroke to the bottom dead center, the applied press load was increased and the internal structure was improved, showing no voids. By increasing the slide speed, the final press load was reduced and shape accuracy was improved through a good pressure distribution on the mold. Measurement of the surface temperature of the sheet during the forming revealed that it remained in the melting region of the resin in the case of fast slide speed, but dropped below the melting temperature in the case of low slide speed. This difference apparently led to spring-in or spring-back after the forming. The experimental results indicate that appropriate balance among press speed, bottom dead center, and sheet temperature is important in the high-cycle forming of CFRTP. © 2016, Fuji Technology Press. All rights reserved.
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| 6.
論文 |
論文
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Tatsuno, Daichi ; Yoneyama, Takeshi ; Kawamoto, Kiichiro ; Okamoto, Masayuki
概要:
The purpose of this study is to elucidate the effect of the cooling rate of the carbon fiber-reinforced thermoplastic (C
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FRTP) sheets on the mechanical property in the press forming within 1 min cycle time. In order to pay attention only to the compression stage after the deformation stage in press forming, a flat sheet of dimensions 200 mm × 100 mm × 3 mm was produced. It was fabricated by stacking 15 CFRTP sheets of 0.2-mm-thick plain woven fabric impregnated with PA6, preheating them to 280 °C and pressing them at 5 MPa using a die cooled from near the melting temperature of PA6 with various cooling rates. Cooling rate of −26 °C/s with pressure holding time (defined in this study as the period that the pressure sensor detects high pressure) of 7 s and that of −4.4 °C/s with pressure holding time of 18 s gave a flexural strength of 536 and 733 MPa, respectively. It was found that the cooling rate during pressure holding is related to the mechanical property of press-formed CFRTP part. © 2017 ASM International<br />Embargo Period 12 months
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