An application for achieving on-machine truing/dressing and monitoring of diamond wheel is dealt with in dry grinding. A dry electrical discharge （ED） assisted truing and dressing method is adopted in preparation of...An application for achieving on-machine truing/dressing and monitoring of diamond wheel is dealt with in dry grinding. A dry electrical discharge （ED） assisted truing and dressing method is adopted in preparation of diamond grinding wheels. Effective and precise truing/dressing of a diamond wheel is carried out on a CNC curve grinding machine by utilizing an ED assisted diamond dresser. The dressed wheel is monitored online by a CCD vision system. It detects the topography changes of a wheel surface. The wear condition is evaluated by analyzing the edge deviation of a wheel image. The benefits of the proposed methods are confirmed by the grinding experiments. The designed truing/dressing device has high material removal rate, low dresser wear, and hence guarantees a desired wheel surface. Real-time monitoring of the wheel profile facilitates determining the optimum dressing amount, dressing interval, and the compensation error.展开更多
A data acquisition system based on LabVIEW is designed and implemented, and electro-discharge(ED) fine truing of metal-bonded fine-grain diamond wheel based on real-time monitoring is researched. Real-time monitoring ...A data acquisition system based on LabVIEW is designed and implemented, and electro-discharge(ED) fine truing of metal-bonded fine-grain diamond wheel based on real-time monitoring is researched. Real-time monitoring not only makes efficient impulse specification of ED truing easily obtained, but also is good for timely identifying no-load, avoiding short circuit and arc discharge phenomena and then for obtaining normal machining state. ED fine truing of the fine-grain wheel includes two steps: rough truing for high efficiency and fine truing for high precision. Final ED truing precision and efficiency not only depend on electric process specification, but also is concerned with electrode shape, insulated performance of operating fluid and vertical feed quantity value and frequency. Experiments indicate that ED fine truing based on real-time monitoring can improve the truing precision and efficiency. Average machining efficiency of W10 wheel is about 0.95 μm/min; the final run-out by ED truing is less than 2 μm.展开更多
In order to investigate safety character of solid propellant, the truing process was analyzed by a thermalmechanical coupled finite element method. Based on the viscoelastic integral constitutive relation, the tempera...In order to investigate safety character of solid propellant, the truing process was analyzed by a thermalmechanical coupled finite element method. Based on the viscoelastic integral constitutive relation, the temperature response in truing process was calculated. The result showed that the maximum temperature in solid propellant truing process could attain up to 65 ℃ when the truing velocity was 10 mm/s and the truing thickness was 1 mm, and there was no remarkable temperature change under the truing thickness of 1.0 mm, 1.5 mm and 2.5 mm. The hazard in truing process of solid propellant was mainly close to the edge of cutting area.展开更多
TRU(Teaching for Robust Understanding in Mathematics)课堂评价模型,是由加州大学伯克利分校与密西根大学共同开发研制的一项数学课堂评价工具,该模型从数学内容、认知需求、学习机会、学生表现度和课堂练习反馈五个维度分析课堂。...TRU(Teaching for Robust Understanding in Mathematics)课堂评价模型,是由加州大学伯克利分校与密西根大学共同开发研制的一项数学课堂评价工具,该模型从数学内容、认知需求、学习机会、学生表现度和课堂练习反馈五个维度分析课堂。本文介绍TRU评价模型的基本框架和特点,探讨该模型带给我国数学教育的启示:重视概念性和过程性学习、学情分析、重视学生自我观点阐述和对他人观点评价。展开更多
基金Research Fund for the Doctoral Program of Higher Education,China(No.20060248031)National Natural Science Foundation of China(No.50775143)
文摘An application for achieving on-machine truing/dressing and monitoring of diamond wheel is dealt with in dry grinding. A dry electrical discharge （ED） assisted truing and dressing method is adopted in preparation of diamond grinding wheels. Effective and precise truing/dressing of a diamond wheel is carried out on a CNC curve grinding machine by utilizing an ED assisted diamond dresser. The dressed wheel is monitored online by a CCD vision system. It detects the topography changes of a wheel surface. The wear condition is evaluated by analyzing the edge deviation of a wheel image. The benefits of the proposed methods are confirmed by the grinding experiments. The designed truing/dressing device has high material removal rate, low dresser wear, and hence guarantees a desired wheel surface. Real-time monitoring of the wheel profile facilitates determining the optimum dressing amount, dressing interval, and the compensation error.
文摘A data acquisition system based on LabVIEW is designed and implemented, and electro-discharge(ED) fine truing of metal-bonded fine-grain diamond wheel based on real-time monitoring is researched. Real-time monitoring not only makes efficient impulse specification of ED truing easily obtained, but also is good for timely identifying no-load, avoiding short circuit and arc discharge phenomena and then for obtaining normal machining state. ED fine truing of the fine-grain wheel includes two steps: rough truing for high efficiency and fine truing for high precision. Final ED truing precision and efficiency not only depend on electric process specification, but also is concerned with electrode shape, insulated performance of operating fluid and vertical feed quantity value and frequency. Experiments indicate that ED fine truing based on real-time monitoring can improve the truing precision and efficiency. Average machining efficiency of W10 wheel is about 0.95 μm/min; the final run-out by ED truing is less than 2 μm.
文摘In order to investigate safety character of solid propellant, the truing process was analyzed by a thermalmechanical coupled finite element method. Based on the viscoelastic integral constitutive relation, the temperature response in truing process was calculated. The result showed that the maximum temperature in solid propellant truing process could attain up to 65 ℃ when the truing velocity was 10 mm/s and the truing thickness was 1 mm, and there was no remarkable temperature change under the truing thickness of 1.0 mm, 1.5 mm and 2.5 mm. The hazard in truing process of solid propellant was mainly close to the edge of cutting area.
文摘TRU(Teaching for Robust Understanding in Mathematics)课堂评价模型,是由加州大学伯克利分校与密西根大学共同开发研制的一项数学课堂评价工具,该模型从数学内容、认知需求、学习机会、学生表现度和课堂练习反馈五个维度分析课堂。本文介绍TRU评价模型的基本框架和特点,探讨该模型带给我国数学教育的启示:重视概念性和过程性学习、学情分析、重视学生自我观点阐述和对他人观点评价。
