成果報告書詳細
管理番号20150000000419
タイトル*平成26年度中間年報 SIP(戦略的イノベーション創造プログラム) 革新的設計生産技術 次世代型高性能電解加工機の研究開発(1)
公開日2015/7/18
報告書年度2014 - 2014
委託先名国立大学法人東京大学
プロジェクト番号P14030
部署名ロボット・機械システム部
和文要約
英文要約Title: Development of High-performance Electrochemical Machining System of Next Generation (FY2014-FY2015) FY2014 Annual Report

(1) Observation of electrochemical machining (ECM) gap phenomena using transparent electrode
The gap phenomena in ECM are complex due to multi-physics interaction among electric field, heat transfer, fluid flow and electrochemical reactions along with complicated electrode surface configurations. This is the reason why the simulation of ECM is difficult. For example, the influence of bubbles existent in the working gap on the current density distribution has not been yet investigated. Hence, the behavior of bubbles was observed using a transparent electrode, and the effect of bubbles on the machining accuracy was investigated. First, the gap with rotating electrode was observed and the contour of the machined surface was measured. It was found that the bubbles gathered at the center of the machining area due to centrifugal force, thereby the center of the machined surface was machined less than the circumferential region.

(2) Mirror-like finishing by electrolyte jet machining
Mirror-like finishing of arbitrary pattern was tried by electrolyte jet machining (EJM). When the jet is still, the workpiece area where it collides into can be selectively finished to a mirror-like surface due to high current density at the center of the jet. When the jet is being translated, the low current density in the radial flow of the impinging jet deteriorates the surface roughness while the jet is passing over the surface. This problem was resolved by reciprocating the jet at a high translating speed. Pulsed current and bipolar pulse also realized mirror-like finishing even at low translating speeds.

(3) Electrolyte jet turning of tungsten carbide micro-rods
Micro-rods made of cemented tungsten carbide were machined electrochemically using electrolyte jet turning (EJT). Bipolar pulse current realized the electrochemical machining of cemented tungsten carbide using NaNO3 aqueous solution as the electrolyte instead of a mixed aqueous solution of NaNO3 and NaOH, which is normally used for the conventional ECM of cemented tungsten carbide, but has hazardous characteristics. A flat electrolyte jet ejected from a slit nozzle was translated along the axis of a rotating rod workpiece to obtain a micro-rod 36 -m in diameter successfully.

(4) Fabrication of micro-electrodes by micro-electrochemical machining with electrostatic induction feeding method
The electrostatic induction feeding method was used to machine micro rods by ECM with ultra-short pulse duration. Since a pulse voltage is coupled to the working gap by a capacitance, electrolytic current flows only at the moment of rise and fall of the pulse voltage. Connecting a diode in parallel to the working gap, mono-polar current pulse could be obtained to avoid the wear of the tool electrode. A stainless steel rod 300-m in diameter was machined using a rectangular parallel piped tool electrode made of tungsten with rotation speed of 3000 rpm, pulse voltage of 110 V, pulse duration of 40 ns, and feed speed of 0.1 mm/s. Electrolyte used was sodium chloride aqueous solution. Surface roughness on the side surface was Ra 0.4 -m. However, the side surface was tapered due to the stray current in the side gap. Pitting corrosion was found frequently at the edge of the end surface of micro-rod, because stainless steel was machined with sodium chloride electrolyte.

(5) Development of electrolyte treatment equipment
To develop a compact electrolyte treatment equipment with high efficiency, state-of-the-art technologies actually used in plants were investigated. Then, fundamental experiments were performed to determine the specifications of the new equipment to be developed. First, some chemicals to reduce hexavalent chromium to trivalent chromium were tested.
ダウンロード成果報告書データベース(ユーザ登録必須)から、ダウンロードしてください。

▲トップに戻る