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First, the function of shaft parts , structural features and technical requirements

Shaft parts is one of the typical machine parts often encountered . It is mainly used to support the transmission parts , transmission torque and load bearing . Shaft parts is a rotating body parts , its length is greater than the diameter of the outer generally cylindrical , conical surface, and the threaded bore and the corresponding end surfaces composed of concentric shaft . Depending on the structure and shape of the shaft axis can be divided into parts , stepped shaft , hollow shaft and crankshaft .

The aspect ratio of the shaft is called the minor axis is less than 5 , greater than 20 is called the elongated shaft axis between the two most .

Shaft bearing , shaft and bearing with section called the journal . Journal is an assembly reference axis , their accuracy and surface quality generally higher, its main function is generally based on technical requirements and working conditions of the development of the shaft , usually have the following :

( A ) the dimensional precision

In order to play the supporting role to determine the position of the shaft journal , usually the size of its high precision (IT5 ~ IT7). Journal size precision transmission parts assembly generally require lower (IT6 ~ IT9).

(B ) the accuracy of the geometry

Geometry precision shaft parts mainly refers to the journal , CONE , such as Morse taper bore roundness , cylindrical , etc., generally it should be within the tolerance limit the size tolerances. For high precision internal and external circular surface , which allows deviation should be marked on the drawing .

(C ) the mutual position accuracy

Positional accuracy of shaft parts is mainly required by the mechanical axis of the location and function of the decision. Should normally ensure transmission parts for assembly journal bearing journal concentricity requirements , otherwise it will affect the transmission parts ( gears, etc. ) of transmission accuracy and noise. General accuracy of the shaft , with the shaft section of the radial journal bearing runout is generally 0.01 ~ 0.03mm, a high accuracy ( such as spindle ) is generally 0.001 ~ 0.005mm.

(D ) surface roughness

General and transmission parts mating shaft surface roughness Ra2.5 ~ 0.63μm, the supporting shaft and the bearing surface roughness compatible Ra0.63 ~ 0.16μm.

Second, the blank shaft parts and materials

( A ) blank shaft parts

According to the requirements of shaft parts , production type, equipment condition and structure , selection bar, forgings, blank form . Little difference to the outer diameter of the shaft , generally the main bar ; while for larger outer diameter stepped away from the axis of the shaft or important , often used in forging , which saves material and reduces the workload of machining , but also improved mechanical properties.

Depending on the scale of production , rough forging the way there are two kinds of freedom and die forgings . Small batch production to use more free forging , swaging when using a large number of mass production.

(B ) material shaft parts

Shaft parts should be based on different operating conditions and requirements and the use of different materials with different heat treatment specifications ( such as quenching , normalizing , quenching , etc. ) in order to obtain a certain strength , toughness and wear resistance.

45 steel shaft parts are commonly used materials , it is cheap after quenching and tempering ( or normalized ) after cutting can get better , but to get high strength and toughness and other mechanical properties , surface hardness after quenching can up to 45 ~ 52HRC.

40Cr alloy structural steel and other suitable medium accuracy and high speed shaft parts , such steel quenched and tempered and quenched , has good mechanical properties.

GCr15 bearing steel and spring steel 65Mn, after quenched and the high-frequency hardening , surface hardness up to 50 ~ 58HRC, and have higher fatigue resistance and good wear resistance , can produce high precision axis.

Precision machine tool spindle ( eg grinding wheel axis , coordinate boring spindle ) can be used 38CrMoAIA nitrided steel . This steel is quenched and surface nitriding , not only to get high surface hardness , but also to maintain a softer core , and therefore impact resistance and good toughness . Compared with the case hardening steel , it has a heat deformation small, higher hardness characteristics. First, the function of shaft parts , structural features and technical requirements

Shaft parts is one of the typical machine parts often encountered . It is mainly used to support the transmission parts , transmission torque and load bearing . Shaft parts is a rotating body parts , its length is greater than the diameter of the outer generally cylindrical , conical surface, and the threaded bore and the corresponding end surfaces composed of concentric shaft . Depending on the structure and shape of the shaft axis can be divided into parts , stepped shaft , hollow shaft and crankshaft .

The aspect ratio of the shaft is called the minor axis is less than 5 , greater than 20 is called the elongated shaft axis between the two most .

Shaft bearing , shaft and bearing with section called the journal . Journal is an assembly reference axis , their accuracy and surface quality generally higher, its main function is generally based on technical requirements and working conditions of the development of the shaft , usually have the following :

( A ) the dimensional precision

In order to play the supporting role to determine the position of the shaft journal , usually the size of its high precision (IT5 ~ IT7). Journal size precision transmission parts assembly generally require lower (IT6 ~ IT9).

(B ) the accuracy of the geometry

Geometry precision shaft parts mainly refers to the journal , CONE , such as Morse taper bore roundness , cylindrical , etc., generally it should be within the tolerance limit the size tolerances. For high precision internal and external circular surface , which allows deviation should be marked on the drawing .

(C ) the mutual position accuracy

Positional accuracy of shaft parts is mainly required by the mechanical axis of the location and function of the decision. Should normally ensure transmission parts for assembly journal bearing journal concentricity requirements , otherwise it will affect the transmission parts ( gears, etc. ) of transmission accuracy and noise. General accuracy of the shaft , with the shaft section of the radial journal bearing runout is generally 0.01 ~ 0.03mm, a high accuracy ( such as spindle ) is generally 0.001 ~ 0.005mm.

(D ) surface roughness

General and transmission parts mating shaft surface roughness Ra2.5 ~ 0.63μm, the supporting shaft and the bearing surface roughness compatible Ra0.63 ~ 0.16μm.

Second, the blank shaft parts and materials

( A ) blank shaft parts

According to the requirements of shaft parts , production type, equipment condition and structure , selection bar, forgings, blank form . Little difference to the outer diameter of the shaft , generally the main bar ; while for larger outer diameter stepped away from the axis of the shaft or important , often used in forging , which saves material and reduces the workload of machining , but also improved mechanical properties.

Depending on the scale of production , rough forging the way there are two kinds of freedom and die forgings . Small batch production to use more free forging , swaging when using a large number of mass production.

(B ) material shaft parts

Shaft parts should be based on different operating conditions and requirements and the use of different materials with different heat treatment specifications ( such as quenching , normalizing , quenching , etc. ) in order to obtain a certain strength , toughness and wear resistance.

45 steel shaft parts are commonly used materials , it is cheap after quenching and tempering ( or normalized ) after cutting can get better , but to get high strength and toughness and other mechanical properties , surface hardness after quenching can up to 45 ~ 52HRC.

40Cr alloy structural steel and other suitable medium accuracy and high speed shaft parts , such steel quenched and tempered and quenched , has good mechanical properties.

GCr15 bearing steel and spring steel 65Mn, after quenched and the high-frequency hardening , surface hardness up to 50 ~ 58HRC, and have higher fatigue resistance and good wear resistance , can produce high precision axis.

Precision machine tool spindle ( eg grinding wheel axis , coordinate boring spindle ) can be used 38CrMoAIA nitrided steel . This steel is quenched and surface nitriding , not only to get high surface hardness , but also to maintain a softer core , and therefore impact resistance and good toughness . Compared with the case hardening steel , it has a heat deformation small, higher hardness characteristics.