利用电子束选区熔化技术制备90°、60°、30°和0°的7 mm TC4钛合金试样板,研究了成形角度对显微组织的影响。结果表明:电子束选区熔化制备的试样具有平行于扫描方向的层带组织;90°、60°和30°试样中的...利用电子束选区熔化技术制备90°、60°、30°和0°的7 mm TC4钛合金试样板,研究了成形角度对显微组织的影响。结果表明:电子束选区熔化制备的试样具有平行于扫描方向的层带组织;90°、60°和30°试样中的β柱状晶贯穿多个层带,其主轴平行于粉末沉积方向,β柱状晶内针状马氏体α'相互交错形成网篮状魏氏组织,β柱状晶和马氏体α'的宽度随成形角度减小而增大;成形角度为0°的试样组织为细长的β晶粒,β晶内α相平行分布形成α集束,各β晶粒中的α集束取向不同。展开更多
Automatic profiling control using a boom-type roadheader requires an understanding of horizontal and vertical swing angles of the cutting boom. In this study the vertical angle of the cutting boom is discussed. First,...Automatic profiling control using a boom-type roadheader requires an understanding of horizontal and vertical swing angles of the cutting boom. In this study the vertical angle of the cutting boom is discussed. First, a vertical swing detection model for the cutting boom is established. Then, a kinematic analysis of the vertical swing mechanism is made and formulae describing the geometrical relationship between the vertical swing of the cutting boom and the telescopic length of vertical hydraulic lift cylinders and vertical swing angle of the boom are presented. Various factors such as complexity of the calculation model, the difficulty of installing the sensor and the cost are compared for two methods. Finally, directly measuring the vertical swing angle of the cutting boom with a tilt sensor is decided to be the more simple and effective method. The detection sensitivity and the vertical cutting error of a tilt sensor are studied. Vibration tests on an EBZ160 roadheader were performed in a coal mine. The characteristic vibration frequencies are analyzed. A design of a vibration isolation mount for the tilt sensor is presented. It makes the detection device work more reliably under conditions where vibration is present and lays a foundation for the implementation of an automatic roadhead cutter. A tilt sensor is installed on an EBZ160 and an EBZ200, and experiments have been done in a coal mine. The re- suits show that the experimental result is favorable and achieves the goal of automatic control of the vertical swing of the cutting boom.展开更多
文摘利用电子束选区熔化技术制备90°、60°、30°和0°的7 mm TC4钛合金试样板,研究了成形角度对显微组织的影响。结果表明:电子束选区熔化制备的试样具有平行于扫描方向的层带组织;90°、60°和30°试样中的β柱状晶贯穿多个层带,其主轴平行于粉末沉积方向,β柱状晶内针状马氏体α'相互交错形成网篮状魏氏组织,β柱状晶和马氏体α'的宽度随成形角度减小而增大;成形角度为0°的试样组织为细长的β晶粒,β晶内α相平行分布形成α集束,各β晶粒中的α集束取向不同。
基金support from China University of Mining and Technology (Beijing)Financial supports for this work provided by the National Hi-tech Research and Development Program of China (No.2008AA062201)
文摘Automatic profiling control using a boom-type roadheader requires an understanding of horizontal and vertical swing angles of the cutting boom. In this study the vertical angle of the cutting boom is discussed. First, a vertical swing detection model for the cutting boom is established. Then, a kinematic analysis of the vertical swing mechanism is made and formulae describing the geometrical relationship between the vertical swing of the cutting boom and the telescopic length of vertical hydraulic lift cylinders and vertical swing angle of the boom are presented. Various factors such as complexity of the calculation model, the difficulty of installing the sensor and the cost are compared for two methods. Finally, directly measuring the vertical swing angle of the cutting boom with a tilt sensor is decided to be the more simple and effective method. The detection sensitivity and the vertical cutting error of a tilt sensor are studied. Vibration tests on an EBZ160 roadheader were performed in a coal mine. The characteristic vibration frequencies are analyzed. A design of a vibration isolation mount for the tilt sensor is presented. It makes the detection device work more reliably under conditions where vibration is present and lays a foundation for the implementation of an automatic roadhead cutter. A tilt sensor is installed on an EBZ160 and an EBZ200, and experiments have been done in a coal mine. The re- suits show that the experimental result is favorable and achieves the goal of automatic control of the vertical swing of the cutting boom.
