Design and Analysis of Manufacturing of Spare Parts for Agricultural Machinery in Bangladesh
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Rundquist, Laura
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Abstract
Farmers in Bangladesh currently import spare parts for agricultural equipment. The high consumption rates and the high costs associated with the purchases create a prime opportunity to develop efficient domestic manufacturing. Domestic manufacturing of agricultural machinery and spare parts will improve the overall manufacturing capability as well as improve the balance of payments in Bangladesh. To benefit domestic manufacturers, this thesis provides an analysis of the manufacturing processes used to fabricate three highly consumed agricultural spare parts: the tiller blade, the threshing tooth, and the fodder chopper blade. The tiller blades are used in power tillers to turn the soil at the beginning of every growing season. The threshing teeth are used in threshing machines that repeatedly hit stalks containing grain to separate and collect the seeds for consumption and the next growing season. The fodder chopper blades are used to cut stalks into small pieces to be used as feed for livestock. Each of these three pieces of equipment performs a crucial agricultural task with great efficiency. Due to their use, components of the machines experience wear and need to be replaced. The manufacturing processes proposed to fabricate these spare parts are applicable and beneficial to current and developing manufacturing facilities within Bangladesh.
The analysis of the manufacturing processes in this thesis is conducted using the following steps. First, the current manufacturing processes for these three spare parts are investigated. Using this information, die designs are generated to fabricate the parts according to their geometries. Hand calculations of the forces required during manufacturing are completed and compared to computer-based simulations. The values provided in this step serve as preliminary estimates for the forces required to perform shearing, forging, and bending operations. The die and workpiece geometries are then loaded into a finite element software, DEFORM, that simulates the forging and bending processes. The results of the simulations are compared to the experimental results obtained at Georgia Tech. In order to perform the experiments, the dies and workpieces are machined in the Montgomery Machining Mall at Georgia Tech. Experimentation took place primarily using an Instron universal testing machine and a Wabash Press. Validation of the simulations is achieved with mesh convergence studies and similarity in the simulation and experimental results comparison.
The forging and bending results are as follows. The tiller blade sharp edge forging die design have an average percent difference of 15.2% for the thickness of the sharpened edge of the blade when comparing the simulation and experimental results using AISI 1100 H-14 aluminum at 20°C. This shows that the edge forging simulations are fairly accurate to realistic experiments with the main source of error being die alignment contributing to the higher deviation. The bending operation performed on the tiller blades have an average percent difference of 10.94% and 1.976% for the final inner angles of the workpieces for the 5-mm and 6-mm thick blades, respectively, between the simulation and experimental results performed with AISI 304 stainless steel at 20°C. There is a low percent difference because of the high surface contact forging incorporated in this deformation operation.
Simulations to create the flanges on the threshing teeth are performed using AISI 4140 steel, and the experiments are performed with AISI 1018 steel because these are the closest property matches to the materials available for stock purchase and in the DEFORM library. The bolt head forging operation is performed at 600°C and the thicknesses of the flanges had a 39.3% average difference from the experiments to simulations. The inconsistencies in experimentation serve as the primary source of error resulting in the high percent difference. The bending operation on the threshing tooth to create its overall shape have average percent differences of 2.45% and 1.81% for the final angle when comparing the simulations to experimental results for the 6-mm and 8-mm diameter rods, respectively. The forging force applied at the end of the bending operation contributed to the low percent difference values. Lastly, the average percent difference for the forging operation to create the flat features on the bent threshing tooth is 1.36% when comparing the thickness of the flats resulting from experimentation to simulations. This operation is the simplest of the forging operations with regard to the die design and final workpiece generated, so there are minimal sources of error.
The die designs presented in this thesis can be implemented in Bangladesh. The bending die designs for the two sizes of both the tiller blades and threshing teeth should be manufactured to the exact angle of the desired final part, and applying additional forging force is recommended following bending to assure the final angle and minimize spring back. The sharp edge forging die design that is recommended is a mirrored design, incorporating a pocket for the workpiece on both top and bottom dies. The bolt head forging die design should be used for a workpiece at a temperature of 600°C or greater to ease workpiece removal. It should be anticipated that unique fixturing for the die geometries will need to be implemented for the various types of manufacturing machinery in Bangladesh. Two flat plates can be used in the simple forging operation of forging the flats on the threshing tooth. A jig may be useful, but not imperative, to ensure that the same geometry of flats is forged with each iteration.
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2024-04-24
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