Ensuring the required manufacturing quality of hydraulic-cylinder rods in mining machines

Abstract

This article presents the results of experimental studies of the finishing treatment by hard turning of the chrome-plated surfaces of critical elements of hydraulic drives of mining machines and hydraulic distribution systems. It was revealed that in the process of galvanic chromium deposition on the working surfaces of the rod and other parts subject to intensive wear, along with provision of physicomechanical and operational characteristics of the surface layer, there is also formation of unacceptable macrogeometric deviations of the parts’ surfaces that are commensurable with the tolerance on the strengthened surface size. It is shown that the deviation from roundness (ovality) formed during chrome plating of the rod’s cylindrical surface is successfully eliminated by hard turning with the cutters equipped with cubic boron nitride plates. At the same time, along with ensuring the specified parameters of dimensional accuracy and geometric shape, the required roughness of the processed surfaces Ra is within 0.32 … 0.26 μm. Thus, the hard turning method can be reasonably recommended as an alternative to polishing, which is widely used after chrome plating of surfaces.The paper presents the methodology of the experiment, the geometrical parameters of cutting plates and technological processing modes, providing the required geometric accuracy and roughness of chrome-plated surfaces.