الفهرس 
Chapter 1 LITERATURE REVIEWOnly 14 pages are availabe for public view
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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.