CNC Machining · 2021年5月7日

Machining center dry goods: cutting tools and applications, engineers must read

1. Analysis of the structure, material and process of shaft parts

1. Function and structure of shaft parts

Shafts are used to support transmission parts and transmit torque or movement. The shaft needs to bear the load during work to ensure a certain degree of rotation accuracy. The machining surface of shaft parts usually has inner and outer cylindrical surfaces, inner and outer conical surfaces, step planes and end planes, as well as threads, splines, keyways and grooves.

2. Materials and blanks of shaft parts

The materials of shaft parts generally include carbon structural steel and alloy structural steel

The blanks of shaft parts include round bars, forgings, and steel castings.

3. Analysis on the processing technology of shaft parts

(1) The common axis is the radial design benchmark for each rotating surface. For shafts with high accuracy requirements, the axis of the center holes at both ends can be used as the radial machining datum; for shafts with low accuracy requirements and for rough machining, the outer circular surface can be used as the machining datum

(2) Machining in the order of rough turning→semi-finishing turning→finishing turning, the shafts with high precision requirements should be arranged for grinding

(3) The spline, keyway, and thread processing on the shaft are arranged after turning and before cutting; for the shaft that needs to be quenched, the thread processing is placed after surface quenching

(4) When the shaft blanks are forgings, normalizing treatment should be arranged, and important shaft parts should undergo multiple heat treatments

Typical process of shaft parts

2. Analysis of gear shaft processing technology

(1) Analysis of parts

(2) Blank selection

(3) Division of processing stages: divided into three stages: roughing, semi-finishing, and finishing

1) Roughing stage: flush the end face, punch the center hole, and rough the outer circle

2) Semi-finishing stage: semi-finishing turning, finishing each external circle, threading, keyway milling, gear milling

3) Finishing stage: study the center hole, rough/finish two outer circles of 20, taper 1:10 truncated cone/30 gear top circle

(4) Benchmark selection: the outer surface and the center hole are used as positioning benchmarks for rough turning, and “one clip, one top” turning is used

Two center holes are used as positioning reference when finishing turning and grinding

(5) Heat treatment process: the quenching and tempering process is placed after the rough turning process and before the semi-finishing process; the gear quenching is before the grinding process

(6) The processing process of single-piece and small-batch production