What’s the fabrication process of bridge girder launcher?
a. the bridge girder launcher mainly uses Q235B steels: the butt welds of cover board and web board, the outer lead weld of cover board and web board adopts Lincoln weld, 
other welds use CO2 gas shielded welding; welding material: welding rod of Lincoln weld H08A, and HJ431; welding rod of CO2 gas shielded welding: ER50-6; the electrode of tack welding uses J422 when the machine is assembled. The 100% ultrasonic inspection should be done for butt welding, the acceptance standard is GB11345-89, and the grade of welding quality is I grade; the welds between cover board and web board adopt melt thru weld, the 100% ultrasonic inspection is done after welded, and I grade is qualified. All of T joints do X-ray detection, the acceptance standard is GB3323-87, and the grade of welding quality is II grade.
b, sand-blasting should be done after the welding is finished, and the derusting grade is Sa2.5; the casting wheel need to do annealing treatment; the NC cutting machine is demanded to cut the steel plate which thickness exceeds 10mm; CNC boring machine is used to process the wheel holes of traveling wheels; the press is used to install the bearing.
c. The paint should be the special paint for engineering machinery, the first layer of outer surface is epoxy zinc-rich primer, the middle layer is epoxy cloud iron paint, and the last two layers is polyurethane paint. The total thickness of paint shouldn’t less than 125μm, and the deviation of right and left is 5μm.
