4-Axis CNC Machine Tool for Relief Grinding Sphere Gear Hob
A new 4-axis machine tool, which is used for relief grind of sphere gears hob including spherical hob, elliptic hob and arc surface hob, is developed. The principle of relief machining of spherical hob is introduced first. Transmitting system, numerical system and some key techniques are then introduced. The machine tool can be reconfigured in machining of arc worms and spatial cams beside of machining of spherical hob. Four forms of the machine tool for machining different workpiece are also introduced. DOI: http://dx.doi.org/10.11591/telkomnika.v10i7.1557
Research on Roll Variable Speed Grinding Based on Adaptive Fuzzy Control
The traditional method of improving the machining precision is mainly on account of changes in the workpiece and the grinding wheel in grinding process, including, considered the weakest of the workpiece from the axial stiffness, using center frame to increase the stiffness of the workpiece, take error compensation, and analyze the mechanism of gear grinding and the suppression measures of variable speed grinding and grinding chatter. Based on the analysis of the relationship among gear grinding mechanism, variable speed grinding and grinding chatter suppression and grinding precision, the variable speed micro-feed grinding process strategy based on adaptive fuzzy control is put up, that is according to the roller material and structure to reasonably determine the characteristics of grinding wheel and the parameters of grinding process. And with full consideration of roll grinders, changes of roller system along the axial stiffness and the deformation control in the roll grinding process, a new strategy of variable speed grinding micro-feed adaptive control optimization based on adaptive fuzzy control is proposed, which for improving the accuracy of the grinding roll presents a new and effective solution.
Improving water use in agriculture : experiences in the Middle East and North Africa
Emerging water shortages are of great concern in many countries of the region. As the agricultural sector is generally by far the most important water consumer and higher priority is given to meeting domestic and industrial water demands, it is to be expected that gradually less water will be available for agriculture. An overview is given of present system and on-farm water use efficiencies and the potential for water savings and yield increases through the use of improved distribution networks and more appropriate irrigation technologies for smallholders. The water conservation efforts of Israel, Cyprus and Jordan are examined in detail with respect to institutions, the irrigation infrastructure, water charges and demand management, operation and maintenance, irrigation scheduling and extension, technology development and transfer, the role of the private sector, quality control on irrigation equipment, land tenure and land consolidation, and water users associations. The World Bank's experience with lending for the irrigation sector in the region is also described. The elements that would need to be considered for inclusion in a national program for water conservation in the agricultural sector are identified.