Rotary tables are equipments in precision machinery applied in five-axis Machine Tools and CMM （Coordinate Measuring Machines）, offering rotational （C-axis） and tilting motion （A-axis）, allowing the obtaining of...Rotary tables are equipments in precision machinery applied in five-axis Machine Tools and CMM （Coordinate Measuring Machines）, offering rotational （C-axis） and tilting motion （A-axis）, allowing the obtaining of several configurations for manufacturing or inspection of parts with complex geometries. The demand for high accuracy, high efficiency and fewer errors in the positioning of the part in precision machines increases every day, thus ensuring their high confidence and the use of aerostatic bearings enable constructive innovations to the equipment. In this context, this work presents the mechanical design, the development and error analysis of a prototype of an aerostatic rotary table. This study emphasizes the analysis of a prototype that uses the air as a working principle for reducing friction between moving parts, increasing the mechanical efficiency, and its influence of motion error is also discussed based on the experimental results. For the geometrical errors analysis, experimental tests were realized in laboratory using a DBB （Double Ballbar）. The tests are performed with only one axis moving, observing the behavior of the system for different feedrate at the C-axis.展开更多
The northern piedmont fault of Wutai Mountain is located at the north of the Shanxi Graben system, which is the dominating fault of the south boundary of the Fanshi-Daixian depression. This paper discusses the fault a...The northern piedmont fault of Wutai Mountain is located at the north of the Shanxi Graben system, which is the dominating fault of the south boundary of the Fanshi-Daixian depression. This paper discusses the fault activity and paleoearthquakes around the Nanyukou segment of the northern piedmont fault of Wutai Mountain during the late Quaternary through field investigation along the fault, measuring geomorphic deformation and excavating trenches at some important sites. From Nanyukou to the southwest of Shanhui, we find obviously dislocated alluvial fans, with strong neotectonic movement at these sites. Since nearly 20ka, the vertical average slip rate is 1.55mm/a to 2.0mm/a. However,since nearly 6ka,it has reached as high as 2.3mm/a, which is twice that on other segments. 2 trenches were excavated around Nanyukou with 6 events discovered. The referenced ages of the events are before 7600a, 6700a - 7600a, 5321a - 5575a, 4400a - 5400a,420Oa-4400a and after 1600a B.P. with approximate recurrence interval 1400a. The latest event is likely to be the earthquake occurring at 512 A. D. ,so it is necessary to do further work to verify this in the future.展开更多
文摘Rotary tables are equipments in precision machinery applied in five-axis Machine Tools and CMM （Coordinate Measuring Machines）, offering rotational （C-axis） and tilting motion （A-axis）, allowing the obtaining of several configurations for manufacturing or inspection of parts with complex geometries. The demand for high accuracy, high efficiency and fewer errors in the positioning of the part in precision machines increases every day, thus ensuring their high confidence and the use of aerostatic bearings enable constructive innovations to the equipment. In this context, this work presents the mechanical design, the development and error analysis of a prototype of an aerostatic rotary table. This study emphasizes the analysis of a prototype that uses the air as a working principle for reducing friction between moving parts, increasing the mechanical efficiency, and its influence of motion error is also discussed based on the experimental results. For the geometrical errors analysis, experimental tests were realized in laboratory using a DBB （Double Ballbar）. The tests are performed with only one axis moving, observing the behavior of the system for different feedrate at the C-axis.
基金sponsored by the specific fund for basic research and industry of Institute of Crustal Dynamics,China Earthquake administration ( ZDJ2008-07,ZDJ2007-14)co-financed by the Joint Earthquake foundation ( C07028)research and special fund for theseismic industry (200,708,028)
文摘The northern piedmont fault of Wutai Mountain is located at the north of the Shanxi Graben system, which is the dominating fault of the south boundary of the Fanshi-Daixian depression. This paper discusses the fault activity and paleoearthquakes around the Nanyukou segment of the northern piedmont fault of Wutai Mountain during the late Quaternary through field investigation along the fault, measuring geomorphic deformation and excavating trenches at some important sites. From Nanyukou to the southwest of Shanhui, we find obviously dislocated alluvial fans, with strong neotectonic movement at these sites. Since nearly 20ka, the vertical average slip rate is 1.55mm/a to 2.0mm/a. However,since nearly 6ka,it has reached as high as 2.3mm/a, which is twice that on other segments. 2 trenches were excavated around Nanyukou with 6 events discovered. The referenced ages of the events are before 7600a, 6700a - 7600a, 5321a - 5575a, 4400a - 5400a,420Oa-4400a and after 1600a B.P. with approximate recurrence interval 1400a. The latest event is likely to be the earthquake occurring at 512 A. D. ,so it is necessary to do further work to verify this in the future.
