慶應義塾研究者情報データベース

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• 2015年04月

  -

  2023年03月

  京都大学, マイクロエンジニアリング専攻, 特任准教授

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• Material removal characteristics in submerged pulsating air jet polishing process

  Han Y., Liu C., Yu M., Jiang L., Zhu W., Qian L., Beaucamp A.

  International Journal of Mechanical Sciences （International Journal of Mechanical Sciences）  257 2023年11月

  ISSN  00207403

  　概要を見る

  In this paper, the material removal characteristics and mechanism of submerged pulsating air jet polishing (SPAJP) process are investigated by polishing experiment on K9 glass and computational fluid dynamics simulation. The experimental results show SPAJP can etch almost perfect Gaussian footprints with high stability. Under comparable condition, SPAJP achieves nearly 300 times higher material removal rate (3.0 × 10−3 mm3/min) than that of traditional fluid jet polishing (FJP) (9.9 × 10−6 mm3/min) at the cost of a moderate degradation in processed surface roughness from Sa 3.97 nm by FJP to Sa 20.49 nm by SPAJP. Jet evolution, abrasive behavior and material removal mechanism in SPAJP are clarified by numerical modeling and experimental jet observation. It is found that SPAJP relies on jet instability of the submerged airflow beam to entrain and accelerate abrasive particles in the slurry, achieving stable and efficient polishing removal on the workpiece surface. To explore the potential of the process for deterministic polishing, an array structure surface is then designed and polished by SPAJP. The processing results are consistent with numerical prediction results, indicating that the new process has good material removal controllability which makes it applicable to deterministic polishing. This study highlights the possibility of using SPAJP to produce ultra-precise surfaces in terms of form control or fabricate high precision optical components in a more efficient and convenient manner.

  • Access to Document (DOI)

• Feed scheduling for time-dependent machining processes by optimization of bulk removal and NC blocks

  Beaucamp A., Mizoue Y., Yamato S., Sencer B.

  Journal of Materials Processing Technology （Journal of Materials Processing Technology）  312 2023年03月

  ISSN  09240136

  　概要を見る

  Time-dependent processes such as CNC fluid jet polishing require feed-rate scheduling through deconvolution of a target removal profile and tool influence function. The dynamic constraints associated with the machine tool driving the process should be considered when solving this numerical problem. This research investigates how material bulk removal affects the scheduled feed-rate and acceleration both in the spatial and time domain, and proposes a method for matching exactly the maximum acceleration with the machine tool limit. Furthermore, the influence of CNC interpolator dynamics is investigated by means of the controller pulse response method. An optimization method for NC blocks is then proposed in order to achieve feed-rates that best match the intended profile. The benefit of bulk removal and NC blocks optimization is validated by fabrication, with and without optimization, of cylindrical Fresnel lenses. Both the shape accuracy and optical performance of the optimally fabricated lens are shown to substantially improve, suggesting that the proposed optimization method has strong potential for industrial application.

  • Access to Document (DOI)

• Hybrid tool combining stiff and elastic grinding

  Pratap A., Yamato S., Beaucamp A.

  CIRP Annals （CIRP Annals）  2023年

  ISSN  00078506

  　概要を見る

  The fabrication process chain for optically smooth surfaces tends to include several time-consuming grinding and polishing steps. To reduce process time, a hybrid tool is proposed in which a stiff grinding tool and a shape adaptive grinding (SAG) tool are fused together, by taking advantage of the elastic nature of SAG tools. The material removal achieved by the hybrid tool is equivalent to discretely using the stiff grinding and SAG tools in sequence. Under similar processing conditions, a smooth surface of ∼0.02 μm Ra can be obtained on BK7 glass with the proposed tool, instead of ∼0.2 μm Ra with the stiff grinding tool.

  • Access to Document (DOI)

• Compliant polishing of thin-walled freeform workpiece

  Zhu W.L., Gao W., Han F., Ju B.F., Chen Y.L., Beaucamp A.

  CIRP Annals （CIRP Annals）  2023年

  ISSN  00078506

  　概要を見る

  Compliant polishing using elastic tools can achieve ultraprecision surface quality on freeform workpieces. However, when it comes to thin-walled parts, the challenge arises with the complex polishing mechanics between the tool and freeform surface, without the knowledge of which the surface form can be easily degraded. To address this, an analytical model is established that can predict the interaction mechanics during polishing. On this basis, two adaptive strategies are proposed. Experiments with controllable material removal verify the high accuracy of the model, and compliant polishing of a thin-walled freeform workpiece with highly precise removal consistency below 0.5 µm was achieved.

  • Access to Document (DOI)

• Reverse Engineering Algorithm for Cutting of Ruled Geometries by Wire

  Beaucamp A.T.H., Takeuchi Y.

  International Journal of Automation Technology （International Journal of Automation Technology）  16 （ 3 ） 349 - 355 2022年05月

  ISSN  18817629

  　概要を見る

  Abrasive wire cutting (AWC) and wire electric discharge machining (WEDM) are efficient and econom-ical processes for the fabrication of precision parts from bulk material. Operating costs and manufacturing lead times are low compared to more general methods such as 5-axis CNC milling, turning, or electro-discharge machining. In this paper, an algorithm based on differential geometry in Euclidean space is proposed for reverse engineering of ruled geometries. The algorithm can determine whether a given geometry is producible by wire cutting, and can also de-rive the associated wire trajectories. Implementation is demonstrated by producing complex turbine blade geometries on 4-axis wire cutting machines with an overall shape accuracy of 20–40 μm peak-to-valley.

  • Access to Document (DOI)

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• システムデザイン工学輪講

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• 生産システム

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• 理工学基礎実験

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• 総合デザイン工学課題研究

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