الفهرس | Only 14 pages are availabe for public view |
Abstract Computer Aided Design (CAD) involves creating computer models defined by geometrical parameters. These models typically appear on a computer monitor as a threedimensional representation of a part or a system, which can be readily altered by changing relevant parameters. CAD systems enable designers to view objects under a wide variety of representations and to test these objects by simulating real conditions. This thesis deals with the study of computer aided design and its application into some parts of machine tools to achieve multiple rollover in areas such as; improving the workshops by re-design and creating programs designed to help and facilitate the design of machines. Gearboxes were the most complicated part in machine tools, so that both design structural modification were taken into consideration in this thesis. A completely new software called GEARBOXLAB was designed and carried out using Visual Basic (VB) language. The software is created to design different types of machine tools (main and feed) gearboxes. It has the ability to design multistage gearboxes [2-4-6-8-9-12-16-18 and 24] output speeds. The design includes [number of speeds, progression type and its common ratio, gears design (module), optimum structural diagram, number of teeth of all gears, gears dimensions (gear width, addendum & dedendum diameters), theoretical speeds, actual speeds, errors between theoretical and actual speeds, speed chart, kinematic diagram of each speed, shafts design, keys design, spline design, shafts axis layout, gear box high, gear box length, gear box width, gear box top cover thickness, gear box wall thickness, gear box base thickness, Fixing bolts and foundation studs, gear meshing frequencies, bearing selection, bearing frequencies, shafts rotating frequencies and Campbell diagram.] Moreover, GEARBOXLAB is used to design the simplified and preselected main gearboxes. Also it can be used to design the different types feed gearboxes such as; Norton, sliding key and variable gears. Several examples of gearboxes were used in testing and validating the software. Results with high accuracy in a shorter time were obtained. The program is fruitful for professional mechanical designers, researchers, students, troubleshooters as well as quality control and vibration engineers in several engineering fields such as machine tools, vehicles and mechanical power transmission. Redesign was applied to the structure of lathe type 1k62 gearbox. This process was done through three stages; using the finite element (FEM) software called ANSYS and experimental testing using the latest instruments of vibration measurements and post processing techniques. Firstly, the gearbox structure was modeled using Solidworks software and exported to ANSYS. The modal analysis was applied to the model, natural frequencies and mode shapes were extracted. The results analysis shows that the high deflection is concentrated in the gearbox cover before applying modification. This results must be validated using experimental testing so that it must be done. Secondly, the modal testing was applied using different techniques such as classical modal analysis (CMA), operation modal analysis (OMA), and operation deflection shape (ODS) to real prototype of gearbox structure. CMA testing was done to validate the FEM software, OMA was made in order to study the vibration under non stationary forces and ODS was extracted to make sure that the high deflected region is in the cover, after validation of FEM and experimental testing the modifications were applied. Thirdly, the modifications were applied to the gearbox model using FEM software. Eleven scenarios were suggested to modify the cover. The modifications were applied using redistribution of cover material. The redistribution is done by removing 0.5 cm of the cover thickness and replacing the same mass with specified ribs. After modelling and analysis of the modifications, the results were compared according to according to increasing in natural frequency and decreasing in deflection values and two modifications were selected. This thesis introduces a CAD application and study in the machine tool design field using different techniques and softwares. |