Shaft parts processing technology

A, the function of shaft parts, structure features and technical requirements
Shaft parts is often met one of the typical parts of the machine. It is mainly used to support the transmission parts, transmission torque and load bearing. Shaft parts is of revolving parts, and its length is larger than the diameter, generally by the concentric shaft within the outer cylinder, cone surface and hole and screw thread and the corresponding face. According to different shape of structure, the axial parts can be divided into optical axis, staircase shaft, hollow shaft and crank shaft, etc.
Axis length to diameter ratio of less than 5 called short shaft, called the slender shaft is greater than 20, most number line somewhere in between.
Shaft bearing, cooperate with TIMKEN Roller Bearings shaft section called a journal. Journal is shaft assembly benchmark, they have higher precision and surface quality of the general requirements, its technical requirements generally formulated according to the axis of the main functions and working conditions, usually have the following items:
(a) dimensional accuracy
Supporting role of journal in order to determine the position of the shaft, usually on the high dimension accuracy requirement (it5 ~ it7). Assembly of transmission shaft neck size precision low general requirements (it6 ~ it9).
(2) the geometry precision
The geometry precision of shaft parts mainly refers to the journal, male cone, Morse taper hole and the roundness and cylindricity, general should limit its tolerance to dimensional tolerance range. For higher accuracy requirement, both inside and outside round surface, should indicate the allowable deviation on the drawings.
(3) the position precision
Axial parts location accuracy is mainly determined by the shaft position and function in mechanical. Usually should guarantee the assembly of transmission shaft neck alignment requirements for supporting shaft neck, otherwise it will affect the transmission precision of transmission parts (gear, etc.), and noise. Average precision of the shaft, the coordinate axis section of the radial runout of supporting shaft neck generally 0.01 ~ 0.03 mm, high-precision shaft (such as spindle) usually is 0.001 ~ 0.005 mm.
(4) the surface roughness
General to match the driver of the diameter of axle surface roughness is ra2.5 ~ 0.63 mu m, to match the bearing of the bearing diameter of axle surface roughness is ra0.63 ~ 0.16 microns.
Second, the blank and shaft parts material
(a) blank of shaft parts
Axial parts can be used according to the requirements, the types of production, equipment conditions and structures, selection of bar, forging blank form. For the cylindrical shaft diameter were similar, general is given priority to with bar; For outside diameter differ big ladder shaft or important, often choose forgings, such already save material and reduce the workload mechanical processing, also can improve the mechanical properties.
According to different production scale, the blank forging method has two kinds of free forging and die forging. Use free forging more medium and small batch production, a large number of die forging in mass production.
(2) shaft parts material
Axial parts should be selected according to different working conditions and requirements of different materials and different heat treatment specifications (such as tempering, normalizing, quenching, etc.), in order to obtain a certain strength, toughness and wear resistance.
45 steel is a commonly used material of shaft parts, it is cheap after tempering (or normalizing) can get better cutting performance, and can obtain the comprehensive mechanical properties such as high strength and toughness, surface hardness after quenching can reach 45 ~ 52 HRC.
40 cr alloy structural steel is suitable for medium accuracy and high speed shaft parts, such as steel after tempering and quenching, has good comprehensive mechanical properties.
Gcr15 bearing steel and spring steel 65 mn, the surface after high frequency quenching, tempering and surface hardness can be up to 50 ~ 58 HRC, and has high fatigue resistance and good wear resistance, can make a high-precision shaft.
Precision machine tool spindle (for example, coordinate boring machine, grinding machine spindle axis) can choose 38 crmoaia nitrided steel. This kind of steel after tempering and surface nitriding, not only can obtain high surface hardness, and can maintain a soft core, good resistance to impact toughness. Compared with carburizing and quenching steel, it has a heat treatment deformation is small, hardness higher characteristic. A, the function of shaft parts, structure features and technical requirements
Shaft parts is often met one of the typical parts of the machine. It is mainly used to support the transmission parts, transmission torque and load bearing. Shaft parts is of revolving parts, and its length is larger than the diameter, generally by the concentric shaft within the outer cylinder, cone surface and hole and screw thread and the corresponding face. According to different shape of structure, the axial parts can be divided into optical axis, staircase shaft, hollow shaft and crank shaft, etc.