engineering portfolio
DESCRIPTION
Past ProjectsTRANSCRIPT
Engineering Project Portfolio
Vladimir Stefanovski B.A.Sc., M.A.Sc. Mechanical Engineer (EIT)
Remote Laser Welding
Today, there is no modern vehicle in which laser welding has not been applied. Scanner welding enables highly productive and flexible production line layouts, making welding in series production faster, more accurate, and thus more cost-effective than traditional welding processes.
Laser welding also opens new doors to increasing component strength to weight ratio by welding more complex components and detailed welding paths. Laser welds have a high strength to length ratio compared to MIG welding. Heat distortion on welded components is also reduced due to the small quick welds with up to 200 welded joints per minute.
With the continuous problem of reducing corrosion on automotive components, automotive suppliers are driven to develop innovative methods for incorporating anti-corrosive coatings. Zinc coated galvanized steel is a common solution, however welding galvanized steel can be extremely difficult since the zinc coating reaches melting temperature before the steel. As a result the global research community has developed v a r i o u s s u r f a c e p r e p a r a t i o n techniques to reduce the negative effects of zinc gas expulsion.
As laser welding technology continues to improve so will the complexity of the welded components along with the ability to cover more detailed applications.
Automated TIG Welding
Multi-layer Gas Tungsten Arc Welding (GTAW) is widely used for refurbishing plastic injection molds. This welding process can provide the high quality weld that is required for molds that will be subject to high temperatures and pressures during production. This refurbishing weld process is currently performed manually, which exposes the we lders to poor work ing conditions. GTA welding is a tedious and time consuming process when compared to other welding processes. The advantages of automating this process are two-fold: removing workers from arduous working conditions, and decreasing production cycle time by increasing the deposition rate through robotic control. Working on a team of mechanical, electrical and software engineers, we were able to successful ly implement this automated process.
Automated TIG Welding
Machine Vision
This system was used for quality control and future experimental work, which measures dimensions of the weld cross-section. The digital images were processed using a Fuzzy Logic filter to remove impulsive noise and to clarify the image. The images were successfully segmented to produce a boundary enclosing the region of interest. This system was capable of achieving an accuracy of 0.01mm. It is now used for weld inspection and quality control in the TIG welding industry.
Cross-section Inspector
Laser Profiler
The laser profiler was developed to be used for measuring bead geometry of weld profiles from experimental work. Extensive image processing algorithms were applied along with an accurate c a l i b r a t i o n t e c h n i q u e . T h e accuracy of the system was calculated to be ±0.1mm. The profiler was also used for real-time control of weld geometry and is currently used in the welding industry.
Numerical Modeling & DOE
The purpose of this study was to investigate the effects of controllable welding parameters on weld bead geometry for standard welding operating ranges when refurbishing plastic injection molds. Another aim was to determine and predict the sensitivity and response, respectively, of base metal orientation on bead geometry. Remanufactured molds require the removal of tool steel, which can be achieved with current CNC machining technology. However, automating the addition tool steel is difficult achieve due to the inherent complexity of the GTA welding process. The work presented in this thesis is an integral component for simplifying the mold remanufacture process by eliminating the guesswork in choosing optimal welding parameters. Through the means of experimental design and statistical analysis, relationships were developed between welding parameters and their effects on bead height, bead width, penetration, heat affected zone (HAZ) depth and HAZ width. The regression models were capable of predicting responses in bead geometry within 1 mill imeter in variation. The resulting regression models can be extended to cold wire GTA welding applications that require high deposition rates and the capabilities of predicting bead geometry for various base metal orientations
Mode l ing resu l ts depend s trong l y on experimental design and input parameter ranges. On average, the percentage error for width and height models was less than 5 percent, ie. 0.12mm error for a typical bead height of 1.2mm. The welding model is now being used in the automation of TIG welding for plastic injection molds.
SAE Supermileage
The purpose of the SAE Supermileage project was to expose students various engineering design and manufacturing processes. The project has gained popularity in part due to the increasing price of fossil fuels and the public’s increasing awareness of environmental effects of automobiles. The vehicle is powered by an internal combustion engine and is driven by a single driver. All structural components are made of light weight materials such as fiberglass and aluminum honeycomb panels. An iterative body design was developed using CFD analysis, which reduced the vehicles drag coefficient to 0.16. The engine was re-designed to be smaller and more fuel efficient. Overall the vehicle was capable of achieving 1230 mpg.
The goal of the power-train team was to modify an existing utility engine to an extremely efficient engine. Over 80% of the original carbureted engine was modified in order to improve fuel consumption. Significant engine modifications include:
•!Reducing the engine displacement from 150 cc to 75cc by inserting a press fit cylinder into the combustion chamber.
•!Over head cam taken from a 75 cc Honda motorcycle
•!Custom designed connecting rod to match the smaller piston head
•!Cold spray weld applied to the piston head used to decrease the combustion chamber volume, thus increasing the compression ration to 12:1.
•!A custom eccentric cam timing chain tensioner was designed for effective belt tension and simplified engine servicing.
Powertrain
Many of the components were designed and manufactured by the specifically for this project. This work is greatly devoted to our supervisor, technicians as well as industry partners. The main design challenges for this project are as follows.
•!Design and analysis of custom connecting rod capable of withstanding high stresses under high temperatures.
•!Estimating the power of the engine by performing an in-depth analytical thermal analysis and comparing the results to numerical and experimental data.
•!Design of and insertion of a press fit sleeve to reduce volume of the engine.
•!Improving the volumetric efficiency by performing CFD analysis on intake and exhaust manifolds.
•!Analyzing the potential stresses in the honey-comb fiberglass/aluminum sandwich panels used in the unique light weight design of the chassis.
Design & Analysis
