Technological Reserves of Improving Grinding Quality of High Speed Steel Plates with Improved Productivity
This study identifies methods of improving the quality of R9M4K8 and R12F3K10M3 high-speed steel plates, the use of which in tool manufacturing is restricted by their low grindability. The roughness parameters Ra and R max (GOST 2789-73) and flatness deviation parameters (GOST 24642-81), namely the basic parameter EFEmax and the supplementary parameters EFEa и EFEq, called the arithmetic and quadratic indexes respectively, are accepted as the output grinding parameters. The Norton 5SG46K12VXP high-porous wheel (HPW) is chosen as an abrasive tool. Its sintercorundum grains have an improved cutting capacity compared to traditional electrocorundum, namely 34AF60K6V5 alloyed chrome. The capabilities of high-porous sintercorundum wheels are shown at the spark-out stage using the non-parametric statistics method, which has advantages compared to parametric evaluations when the conditions of homoscedastic and normalcy distribution are violated. Univariate distributions of frequencies by medians have shown that sparking-out of the high-speed plate provides the most significant decrease of median flatness deviation (up to 1.25-1.3 times), with the spark-out pass j = 6 for the R9М4К8 plate, and j = 8 for the R12F3К10М3 plate. For the R12F3К10М3 plate, the parameter R max is decreased by one categorical magnitude (CM) according to GOST 2789-73, and the parameter Ra is decreased within the CM range. For the R9М4К8 plate, the heights Ra and R max are characterized by the values 0.05 and 0.32 mcm respectively, and lie in the range of CM. The specified number of spark-out passes is also taken into consideration when the accuracy of the process is assessed.