Low stiffness and positioning problems are difficulties and challenges in the precise machining of near-net-shaped blades.This paper aims to achieve high accuracy in manufacturing by fixture-and deformation-control in...Low stiffness and positioning problems are difficulties and challenges in the precise machining of near-net-shaped blades.This paper aims to achieve high accuracy in manufacturing by fixture-and deformation-control in the adaptive CNC machining process.Adaptive CNC machining technology is first analyzed,and new fixture-evaluation criteria and methods to evaluate the adaptive CNC machining process fixture design are built.Second,a machining fixture is designed and manufactured after analyzing its positioning scheme,clamping scheme,materials(PEEK-GF30),and structure characteristics.Finally,the designed fixture is analyzed by FEA and experimentally verified by a cutting experiment.The results show that the deformation of the blade is an overall rigid-body displacement,the main deformation of the blade-fixture system occurs on the four clamping heads,and this fixture can effectively protect the blade from local deformation.The proposed clamping-sequence method reliably and effectively controls the local maximum deformation of the blade.The system stiffness is increased by 20 Hz,with each clamping force increased by 200 N.Both high-and low-frequency displacement in roughing milling or finishing milling are acceptable relative to the accuracy demand of blade machining.This fixture and an adaptive CNC machining process can achieve high accuracy in blade manufacturing.展开更多
We report the convenient synthesis of a benzobis(imidazolium)-embedded conjugated polyelectrolyte pBBI by a Cu-catalyzed direct C–H arylation of a cationic benzobis(imidazolium)monomer with a di-iodide comonomer.pBBI...We report the convenient synthesis of a benzobis(imidazolium)-embedded conjugated polyelectrolyte pBBI by a Cu-catalyzed direct C–H arylation of a cationic benzobis(imidazolium)monomer with a di-iodide comonomer.pBBI shows weak fluorescence in solution due to rotation of the repeat units in the conjugated backbone,and enhanced fluorescence when electrostatically interacting with a variety of an-ions to form aggregates.Specially,pBBI responds to the bisulfite anion with intensified unique deep-blue fluorescence easily discriminated by naked eye.展开更多
Naphthyridine-fused bisimidazolium salts were designed and synthesized for the first time. The study of the Cu(Ⅱ) and Pd(Ⅱ) complexes demonstrated that the deprotonated dicarbene ligands are rigid chelating C,C-liga...Naphthyridine-fused bisimidazolium salts were designed and synthesized for the first time. The study of the Cu(Ⅱ) and Pd(Ⅱ) complexes demonstrated that the deprotonated dicarbene ligands are rigid chelating C,C-ligands with strong electron-donating ability in analogy with the classic phenanthroline N,N-ligands.展开更多
基金supported in part by Xi’an Aero-Engine(Group)Ltd.National Key Scientific Instrument and Equipment Development Project(2016YFF0101900)+1 种基金National Natural Science Foundation of China(Grant 51575310)Beijing Municipal Natural Science Foundation(Grant 3162014)。
文摘Low stiffness and positioning problems are difficulties and challenges in the precise machining of near-net-shaped blades.This paper aims to achieve high accuracy in manufacturing by fixture-and deformation-control in the adaptive CNC machining process.Adaptive CNC machining technology is first analyzed,and new fixture-evaluation criteria and methods to evaluate the adaptive CNC machining process fixture design are built.Second,a machining fixture is designed and manufactured after analyzing its positioning scheme,clamping scheme,materials(PEEK-GF30),and structure characteristics.Finally,the designed fixture is analyzed by FEA and experimentally verified by a cutting experiment.The results show that the deformation of the blade is an overall rigid-body displacement,the main deformation of the blade-fixture system occurs on the four clamping heads,and this fixture can effectively protect the blade from local deformation.The proposed clamping-sequence method reliably and effectively controls the local maximum deformation of the blade.The system stiffness is increased by 20 Hz,with each clamping force increased by 200 N.Both high-and low-frequency displacement in roughing milling or finishing milling are acceptable relative to the accuracy demand of blade machining.This fixture and an adaptive CNC machining process can achieve high accuracy in blade manufacturing.
基金support from the National Natural Science Foundation of China(No.21772134)the Fundamental Research Funds for Central Universities(No.20826041D4117).
文摘We report the convenient synthesis of a benzobis(imidazolium)-embedded conjugated polyelectrolyte pBBI by a Cu-catalyzed direct C–H arylation of a cationic benzobis(imidazolium)monomer with a di-iodide comonomer.pBBI shows weak fluorescence in solution due to rotation of the repeat units in the conjugated backbone,and enhanced fluorescence when electrostatically interacting with a variety of an-ions to form aggregates.Specially,pBBI responds to the bisulfite anion with intensified unique deep-blue fluorescence easily discriminated by naked eye.
基金the National Natural Science Foundation of China (No. 21772134)the Fundamental Research Funds for the Central Universities (No. 20826041D4117)。
文摘Naphthyridine-fused bisimidazolium salts were designed and synthesized for the first time. The study of the Cu(Ⅱ) and Pd(Ⅱ) complexes demonstrated that the deprotonated dicarbene ligands are rigid chelating C,C-ligands with strong electron-donating ability in analogy with the classic phenanthroline N,N-ligands.
