CALCULATION OF CONTACT TENSIONS IN CONJUGATE SURFACES IN SPHERE GLOBOIDAL RUSK SYNCHRONOUS CARDAN HINGE

The paper presents  a calculation of contact tensions between conjugate surfaces in sphere globoidal rusk synchronous cardan hinge on the condition that there is power balance at the constant torque on the output shaft. The required torque effect on the intake shaft at the constant angular velocity  has been calculated with the help of the Hertz’s theory of contact deformations . The maximum contact pressure has been ascertained through the torque which determines strength of the cardan hinge, its durability, wear rate in  the conjugate friction pair. The paper investigates transmission dependence of the maximum torque while changing  material quality and according to various typical sizes of the cardan hinge. Dependences of the calculated maximum torque value on material strength have been demonstrated graphically  in the logarithmic coordinate system.  A formula for maximum contact pressure value has been derived and it determines  strength of the hinge mechanism, its durability and wear rate  in the conjugate friction pair.

The effect of geometrical relationship between a spherical cam radius and a globoidal  surface radius of a hinge contact has been determined with the purpose to analyze optimal design parameters of the sphere globoidal rusk synchronous cardan hinge. It has been established that permissible torque in the hinge mechanism grows with a quadratic dependence while increasing a cam radius and  the torque is proportionally growing while increasing an axis radius of globoidal rusk surface on which spherical cams are set. The maximum permissible torque value grows with a cubic dependence while using qualitative material with thermally treated surface and application of lubrication materials which tolerates significant (up to [σ] = 1000 MPa) contact loads.  Two-fold increase of typical size of the sphere globoidal rusk synchronous cardan hinge leads to an 8-fold increase of the permissible transmitted torque.

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