NEW MATERIALS FOR IMPLANTS OF THE HUMAN HIP JOINT AND TECHNOLOGY OF THEIR MACHINING WITH THE ACHIEVEMENT OF HIGH PRECISION AND QUALITY OF SPHERICAL SURFACES
DOI:
https://doi.org/10.20535/2305-9001.2015.75.54304Keywords:
End-prostheses of joints, bearing surfaces, wear, friction coefficient, single crystal sapphire, anisotropy, precision grinding, spherical surfaceAbstract
In view of the fact that the endo-prosthesis heads of human hip-joint are operated in extreme conditions, in respect of load, the selection of corresponding material and also increase of precision and quality of machining of spherical surfaces is rather topical task. In the submitted work are reviewed the problems connected with the definition of the influence degree of orientation of the sapphire crystal on its workability during the diamond grinding with the ring end. For conduct of investigations of workability of the sapphire crystal the method of low temperature precision grinding (LPG) was chosen elaborated at the Department of Mechanical Engineering of the Georgian Technical University as a version of progressive methods for grinding of hard and brittle non-metallic materials. On the basis of analysis of the existing kinematic schemes and technological processes of obtaining spherical surfaces the new more effective scheme has been suggested that provides the increase of precision of spherical surfaces. The essence of the scheme is in the selection of optimal ranges of the ratio of rotational speeds of the article and tool and in equal distribution of the article pressing to the grinding ring by the analog of the LPG method that is the pledge of exclusion of unequal wear of the abrasive tool, achievement and support of high precision of the work surface and by that the machining precision of the surface of incomplete surface.
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