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
Design of Lighting System for Surface Mine Projects
Indian mining illumination standard is based on incident light without mentioning about uniformity ratio. But CIE (International Commission on Illumination, Austria) stresses upon uniformity ratio as well. In a mine because of low surface reflectance, the surrounding illumination level is much lower than the minimum lighting standard, as specified by various regulatory bodies. The surface brightness further reduces in wet surface condition, resulting in poor visibility. In the present study, design has been made both in mineral and overburden benches based on minimum acceptable reflected light and reflected uniformity ratio. For the sake of comparison of various types of lighting systems, a stretch of 1.0 km long haul road was considered and design was attempted with five different types of luminaries. Lamp mounting heights have been varied at five steps, namely 8, 10, 12, 14 and 16 m. Design under wet condition would incur an excess cost of about 9.4 % for mineral bench and about 50 % for overburden bench haul roads under study. Thus designing under wet surface condition would ensure minimum light level even under worst condition of surface reflectivity, with marginal increase in cost.
Design of haul road lighting system. Part I: design based on optimal energy considerations
Electrical energy consumption is a major cost component of haul road lighting. Haul road lighting depends on many parameters such as type and wattage of sources, mounting height and tilt angle of light fixtures. In this study a computer model has been developed for optimum energy consumption of any haul road lighting system. Using the program, illumination design was studied for a stretch of 800 m long haul road. Nine different types of light sources were considered for mounting heights of 12 and 16 m. High-pressure sodium vapour (HPSV) lamps of 100 W proved to be energy efficient at a 12 m height whereas at 16 m height, energy consumption was minimum for 150 W HPSV lamps. Thus the developed computer program proved to be successful in evaluating the performance of lighting designs from the point of view of energy consumption.