Input shaft: forging and blank making → normalizing → finishing turning → gear rubbing → drilling → gear shaping → undercut angle → hobbing → shaving → heat treatment → grinding → meshing and finishing.
Output shaft: forging billet → normalizing → finishing turning → rolling gear → shaving → heat treatment → grinding → meshing and finishing.
- Specific process flow
(1) Forging billet
Hot die forging is a widely used blank forging process for automobile gear parts. Computer gong processing, Dongguan computer gong processing, high speed computer gong processing, mechanical parts processing, computer gong processing
Hot forging and cold extrusion are widely used in the past. In recent years, cross wedge rolling technology has been widely used in shaft machining. This technology is especially suitable for the production of complex stepped shafts. It not only has high precision, small machining allowance, but also has high production efficiency.
(2) Normalizing
The purpose of this process is to obtain the hardness suitable for subsequent gear cutting and to prepare the microstructure for the final heat treatment, so as to effectively reduce the heat treatment deformation. Due to the influence of personnel, equipment and environment, the normal normalizing can not control the cooling rate and cooling uniformity of workpiece, resulting in large hardness dispersion and uneven microstructure, which directly affects machining and final heat treatment.
(3) Finish turning
In order to meet the positioning requirements of high-precision gear machining, CNC lathe is used for the finish turning of gear blank. First, the inner hole and locating end face of the gear are machined, and then the machining of the other end face and outer diameter is completed synchronously. It not only ensures the perpendicularity requirement between the inner hole and the locating end face, but also ensures the small size dispersion in the mass production of gear blanks. Thus, the accuracy of gear blank is improved and the machining quality of subsequent gear is ensured.
There are mainly three ways of positioning datum and clamping for shaft parts processing
Positioning by the center hole of the workpiece: in the machining of the shaft, the coaxiality of the outer circle surface and end face of the part, and the perpendicularity of the end face to the rotating axis are the main items of their mutual position accuracy. The design basis of these surfaces is generally the center line of the shaft. If two center holes are used for positioning, it is in line with the principle of datum coincidence.
- Outer circle and central hole as the positioning reference (one clip and one top): Although the centering accuracy is high, the rigidity is poor, especially when machining heavy workpieces, and the cutting parameters cannot be too large.
In rough machining, in order to improve the rigidity of the parts, the cylindrical surface of the shaft and a central hole can be used as the positioning reference. This positioning method can bear large cutting torque and is the most common positioning method for shaft parts.
- Take two cylindrical surfaces as positioning datum: when machining the inner hole of hollow shaft (for example: machining the inner hole of Morse taper on the machine tool), the central hole cannot be used as the positioning reference, and the two outer cylindrical surfaces of the shaft can be used as the positioning reference. When the workpiece is the spindle of machine tool, the two supporting Journal (assembly reference) is often used as the positioning reference, which can ensure the coaxiality requirement of the taper hole relative to the supporting journal, and eliminate the error caused by the non coincidence of the reference.
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