Today, we will discuss the use of a solid shaft and bearing bore in theBasic calculations of press fit and pullout forces for bearings.It is a note about.
In the previous article, I wrote about press-fit calculations for "hollow shaft and bearing bore," and this time I would like to calculate what would happen if the shaft were solid.
Press-in calculation
Solid shafts require more press-fit force than hollow shafts.
When press-fitting a bearing into a shaft, it is better to press-fit a solid shaft than a hollow shaft.A large press-in force is required.
This is because there is no place for the force to escape from the solid shaft compared to the hollow shaft. In particular, as mentioned in the previous issue, the difference is about the same as the calculated value if the jig can be used to press-fit the shaft straight, but if the jig is not appropriate, the difference may be much larger than the calculated value.
Press-fit and pull-out forces when press-fitting a solid shaft into an inside diameter
This calculation sheet is also based on NTN's "Rolling Bearing Handbook" and NSK's "Technical Report" as in the previous report.
Items required for calculation
d Diameter [shaft or inner ring] (mm)
Smax Maximum design interference (mm)
Smin Minimum design interference (mm)
G Decrease in amount of shime allowance (μm)
D Outer diameter of bearing (mm)
B Bearing width (mm)
E Modulus of elasticity (MPa)
μ1 Friction coefficient
μ2 Friction coefficient
Calculation of press-in and pull-out forces
- Find the effective threshold of the assumed intermediate value
S''[mm]=(((Smax-Smin)/2)+Smin)-(G/1000)
- Find inner ring raceway diameter (average groove diameter) (adopt general formula)
D1[mm]=1.05*(((4*d)+D)/5)
- Find the ratio of shaft diameter to inner ring raceway diameter
k[-]=d/D1
- Find the fit surface pressure in the case of a solid shaft
Pm[N/mm^2]=(S''/d)*(1/((((P-1)/(P*E))-((3.33-1)/(3.33*208000)))+(2/(208000*(1-k^2)))))
- Find the maximum circumferential stress on the inner ring bore mating surface
τmax[N/mm^2]=Pm*((1+k^2)/(1-k^2))
- Find the force required to insert the inner ring and shaft.
K[N]=μ1*Pm*3.14*d*B
- Find the force required to pull the shaft out of the inner ring.
H[N]=μ2*Pm*3.14*d*B
Download Calculation Excel
Here you can download an Excel sheet for "Press Fit Calculations for Solid Shaft and Bearing I.D.". Please use it.
