A finish
machining method for an internal spline input shaft is characterized by comprising the following steps: with central holes in two ends of the input shaft as a reference and the central axes of the central holes as a
machining axis, firstly, performing finish turning on the central holes in the two ends of the input shaft, outer circles of bearings and positioning end surfaces by using a double-end
numerical control lathe; and then the input shaft is sequentially subjected to internal spline
broaching, gear
hobbing, heat treatment, outer circle
grinding at the two ends, inner hole finish turning at the two ends and
gear grinding. The invention ensures the coaxiality of the reference of the center holes at the two ends of the input shaft, ensures that the excircle of the bearing is consistent with the reference of the center holes, effectively reduces the eccentric error of the center holes at the two ends and the excircle of the bearings at the two ends, reduces the error
magnification of subsequent finish
machining, improves the overall precision of the product, and improves the concentricity of the assembled bearings at the two ends of the input shaft. Transmission reliability of the input shaft is improved, transmission
noise is reduced, finish machining takt of the input shaft is accelerated, finish machining efficiency is improved, and production benefits are improved.