Laser welding of gasoline injectors and laser welding parameters

HDEV5 is a fuel injection system which is used gasoline engine. It has several advantages like %15 fuel saving in comparison with gasoline injectors which have been used up to now, %5 more torque and instantly reaction manner. These advantages are prior criterias when the customers selected product.In this thesis, HDEV5 gasoline injectors are welded with a laser welding which works with continous wave method. The laser welding and laser welding parameters of the injectors are investigated considering welding quality and their mechanical properties. In addition welding failures due to laser welding parameters are taken into consideration. Some solutions to these specific problems are proposed. A laser power optimization study is carried out and with improvement of the values of run-out and centreline welding, shielding gase and vacuum parameters are selected so that major failures such as the crack on the weld and uncombined weld are substantially decreased. Valve ball-valve needle part welded area tensile strength values are previosly between 900-1500 N. The tensile strength has been increased to 1400-1900 N range with the present optimization study. At the same time stabilisation of cooling velocity and canceling pre-heating step during laser welding sequence solve the problem of cracks. In this thesis the study is focused on of laser welding of some significant injector's parts (valve ball, valve needle, valve seat, valve housing) and the effect of laser welding parameters are investigated on these parts. The quality of the welding is observed with preparing of metallographic samples. Vickers hardness measurements are taken into account. Scanning electron microscope images are taken. Finally, the effects of laser welding parameters of mechanical properties are tried to observe with tensile test on valve ball-valve needle parts.Key Words: Laser Welding, HDEV5 Gasoline Injectors, Laser Welding Parameters