PARTICULARITIES OF MAGNETIC-ABRASIVE MACHINING OF RODS OF HYDRAULIC CYLINDERS

Abstract

Obtaining high parameter of roughness of chrome-plated surfaces with rather big productivity and accuracy of geometrical parameters represents a serious problem. A process of magnetic and abrasive processing of rods of hydraulic cylinders which provides reduction of roughness of working surfaces is considered. Hydraulic cylinders which have been made of steel 20Cr GB 3077-88 were used as samples. Samples were exposed to heat treatment to HRC 61–64, grounded to obtain roughness of a surface of Ra 0.8 microns, prepared for chromium plating by polishing by the method of magnetic and abrasive processingand then chromeplated (thickness of a layer of chrome of 0.02–0.03 mm). The conducted researches of magnetic and abrasive processing of the chrome-plated rods of hydraulic cylinders have shown that the roughness of a surface decreases by 54 % at change of time of processing from 60 to 150 seconds. Further increase of the processing time leads to falling of intensity of material removal therefore decrease of a roughness at time of processing within the range from 60 to 210 seconds is equal to 61 %. Application of the method of magnetic and abrasive processing for rods of hydraulic cylinders before their chromium plating has provided the decrease of roughness Ra from 0.8 to 0.2 microns in 90 seconds of processing. It allows drawing a conclusion that the mechanism of process of magnetic and abrasive processing, which provides mass and dimensional removal of metal of chrome-plated surfaces is similar to the processes of treatment of not chrome-plated ones. The difference of removal intensity is explained by the fact that the chromic covering of details, having considerable wear resistance and hardness, interferes with more intensive course of process.