The invention relates to the technical field of spline shafts, in particular to a high-precision rectangular spline shaft manufacturing process. According to the high-precision spline shaft manufacturing process, first, materials are selected, namely, 40Cr materials (selected according to the requirement) are adopted; second, rough turning
machining is conducted on the spline workblank; third, thermal refining is conducted, wherein the rigidity HB is 250-280, and spline shaft
core strength is improved; fourth, digital controlled lathe semi-finish turning is conducted, wherein a reserved bearing block margin is 0.3-0.5mm; fifth, spline rolling is conducted, namely, a spline milling
machine for a
grinding hob is used for
machining the spline width and the bottom
diameter, the margin of 0.3-0.4mm is reserved; sixth,
quenching (heating
processing) is conducted, namely, high-frequency
quenching is adopted at the spline position, the rigidity HR is 48-53, and the rigidity of the spline position is improved; seventh, external
diameter grinding of a
cylindrical grinding machine is conducted (drawing technical requirements are met as needed); eighth, spline
grinding is conducted, namely, a molding
gear grinding machine is adopted, and a
grinding wheel is corrected; ninth, the spline size is detected. The high-precision rectangular spline shaft manufacturing process improves the precision of the spline shaft, and improves working efficiency.