Method for processing slant oil hole in middle-speed machine crankshaft

The invention relates to a method for processing an oblique oil hole of a crankshaft of a medium speed machine. A gun drill with length-diameter ratio of 30:1 is adopted for drilling and cutting; thedrilling and cutting process of the gun drill comprises the drilling and cutting of a guide hole and an oil hole; the diameter of the guide hole is larger than that of the gun drill by 0.01 to 0.02 mm; the depth of the hole is double of the diameter of the gun drill; in the process of drilling and cutting the guide hole, high-pressure mixed cold air is used to spray and cool temperature; chips aredischarged; the oil hole is drilled and cut by stages; a short gun drill drills first and machines the oil hole to the depth of between 300 and 310 mm; after the gun drill passes through a crossed hole, a long gun drill replaces the short gun drill and drills and machines the oil hole to the depth of 709 mm to the crossed hole; a plug is used to plug the processed oblique oil hole; the plug is fixed by screw threads; the