The technical requirements for non-standard parts processing are generally formulated according to the main functions and working conditions of the shaft, and generally include the following:
(a) The surface roughness of precision parts is generally Ra2.5~0.63 for the shaft diameter matched with the transmission parts μ m. The surface roughness of the supporting shaft diameter matched with the bearing is Ra0.63~0.16 μ m。
(b) Mutual position accuracy of precision parts the position accuracy requirements of non-standard parts processing are mainly determined by the position and function of the shaft in the machine. Generally, it is required to ensure the coaxiality between the journal of the assembled transmission parts and the supporting journal, otherwise the transmission accuracy of the transmission parts (gears, etc.) will be affected and noise will be generated. For the shaft with ordinary precision, the radial runout of its mating shaft segment to the supporting journal is generally 0.01~0.03mm, and that of the high-precision shaft (such as the main shaft) is generally 0.001~0.005mm.
(c) Geometric form accuracy of precision parts Geometric form accuracy of non-standard shaft parts mainly refers to roundness and cylindricity of journal, outer cone, Morse taper hole, etc. Generally, its tolerance should be limited within the range of dimensional tolerance. For inner and outer circular surfaces with high accuracy requirements, their allowable deviations shall be marked on the drawings.
(d) The dimensional accuracy of non-standard parts is generally high (IT5~IT7) in order to determine the position of the shaft for Kunshan machined journal that plays a supporting role. The dimensional accuracy of journal for assembling transmission parts is generally required to be low (IT6~IT9). Centering type CNC lathe for precision parts (centering machine/slitting lathe) is a kind of CNC machine tool mainly used for precision machining of shafts and non-standard shafts. It has made a qualitative leap in processing efficiency and processing accuracy compared with CNC lathe. Because of the use of dual axis cutter arrangement, the processing cycle time is greatly reduced. By shortening the tool exchange time between cutter arrangement and counter cutter table, multiple cutter tables overlap, The effective axis of thread chip can move and overlap, and the direct spindle indexing function during secondary processing can shorten the idling time. The chip cutter is always processed at the clamping position between the spindle and the workpiece, ensuring that the processing accuracy remains unchanged. At present, the maximum machining diameter of the centering machine on the market is 42mm, which has great advantages in the precision shaft machining market. This series of machine tools can be equipped with an automatic feeding device to realize the fully automatic production of a single machine tool and reduce the labor cost and the rate of defective products. Non standard parts processing is very suitable for mass production of precision shaft parts.
