左手，右手

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First, the selection principle of clearance:

    1, a more tight fit, a larger temperature difference between inside and outside the ring, need to reduce the friction torque and large deep groove ball  Thrust Bearing axial load or the need to improve the performance of the occasion aligning, clearance should be using a large group.

    2, when the rotation with high precision, or to strictly limit the axial displacement, the appropriate use of small clearance group.

    Second, with the clearance-related factors:

    1, with the bearing inner ring and shaft.

    2, the bearing outer ring and housing with the hole.

    3, the temperature.

    Note: The amount of radial clearance with the mating parts to reduce the actual size of the effective amount of interference, match the shaft size, shell thickness on the hole.

    1, the real effective amount of interference (inner ring) should be: △ dy = 2 / 3 △ d - G * △ d is

    Nominal amount of interference, G * is flattened, the interference fit dimensions.

    2, the real effective amount of interference (outer ring) should be: △ Dy = 2 / 3 △ D - G * △ D is

    Nominal amount of interference, G * is flattened, the interference fit dimensions.

    3, the heat will cause the temperature inside the bearing, and then lead to shaft, bearing and bearing parts of the expansion. Clearance can increase or decrease, depending on the shaft and housing materials, as well as between parts of rolling Special Bearing and bearing temperature tonsure.

    Third, the clearance formula:

    (1): Coordination in

    1, the bearing inner ring and steel solid shaft: △ j = △ dy * d / h

    2, the bearing inner ring and the steel hollow shaft: △ j = △ dy * F (d)

    F (d) = d / h * [(d/d1) 2 -1] / [(d/d1) 2 - (d / h) 2]

    3, the bearing outer ring and solid steel shell: △ A = △ Dy * H / D

    4, the Pressed Bearing outer ring and steel thin-walled shell: △ A = △ Dy * F (D)

    F (D) = H / D * [(F / D) 2 - 1] / [(F / D) 2 - (H / D) 2]

    5, the bearing outer ring and cast iron case: △ A = △ Dy * [F (D) - 0.15]

    6, the bearing outer ring and the light metal casing: △ A = △ Dy * [F (D) - 0.25]

    Note:

    △ j - the diameter of the inner ring raceway wall expansion volume (um).

    △ dy - the amount of interference and effective journal (um).

     d - Bearing diameter nominal size (mm).

     h - Ribs inner ring raceway diameter (mm).

     B - Bearing Width (mm).

     d1 - hollow shaft diameter (mm).

    △ A - diameter of the outer ring raceway wall shrinkage (mm).

    △ Dy - practical and effective housing diameter the amount of interference (um).

     H - the outer ring raceway wall diameter (mm).

     D - bearing outer ring and the shell holes of the nominal diameter (mm).

     F - bearing shell diameter (mm).

    (2): temperature

    △ T = Гb * [De * (T0 - Ta) - di * (Ti - Ta)]

    Гb for the linear expansion coefficient of which, bearing steel is 11.7 * 10-6 mm / mm / 0C

    De diameter of the outer ring raceway, di inner raceway for the bearing diameter.

    Ta is ambient temperature.

    For the bearing outer ring temperature T0, Ti bearing inner ring temperature.

    Fourth, axial clearance and radial clearance of the relationship:

    Ua = [4 (fe + fi - 1) * Dw * Ur - Ur2] 1 / 2

    Ur because of radial clearance is small, so Ur2 very small, Needle Roller Bearing negligible.

    Therefore, Ua = 2 * [(fe + fi -1) * Dw * Ur] 1 / 2

    Which is the outer ring groove curvature coefficient fe, fi for the inner ring groove curvature coefficient, Dw for the ball diameter.