Design of Planetary Gearbox

Abstract

The gearbox is to be used in the Fluidized bed dryer (FBD) of the pharmaceutical and chemical plants. The FBD is used for drying of powder and similar wet materials at slow speed, after mixing and granulation. As per the present practice the drive is placed outside the container and bought out speed reducer is mounted on the container. At the centre of the container there is another factory made bevel gear box used for speed reduction and direction change, which increases the cost and energy loss. To solve this problem, planetary gearbox in association of bevel gear in a single case is going to be designed. It may solve the problem of two gearboxes and loss of energy as planetary and bevel gears are directly connected. DESIGN OF BEVEL GEAR: Before attempting the design procedure thorough knowledge of bevel gear is required. For that different references are used and detailed study is carried out. For the given problem data bevel gear design is carried out. All the conditions for the design are checked and iterations are carried out if needed. Design calculations are done manually, MS Excel as well as using the software MathCAD. DESIGN OF PLANETARY GEAR TRAIN: Planetary gear train is used when very high ratio is required with compactness. It contains the central sun gear surrounded by planet gears and one ring gear. Ratio calculation in planetary gear train is the important. For this different methods are available. Here tabular method is used. Ratio range for planetary gear train is specified everywhere. There is some limitation in the ratio as it consist sun gear, planet gear and ring gear. iv To achieve higher ratio, planetary gear in SERIES is used. Both the gear trains are identical and so there is no increase in cost of production as well as no increase in inventory. Output of one train is the input of the second train. DESIGN OF SHAFT AND BEARING SELECTION: A shaft is a rotating machine element, which is used to transmit power from one place to another. The power is delivered to the shaft by some tangential force and the resultant torque or twisting moment set up within the shaft permits the power to be transferred to various machines linked to the shaft. Here gears are mounted on it. So gears are exerting force on shaft. Also bearing load is also an important for design of shaft. After calculating all types of load acting on shaft, free body diagram is to be drawn for better understanding. Here shaft experiences twisting moment as well as bending moment due to gears mounted on it. Shaft is subjected to the case of combined twisting and bending moments. So design is carried out on this basis. Now shaft diameter is known. Also bearing load is known. Assuming life of bearing, bearing is selected by following the steps given in the catalogue published by bearing manufacturer.