СOMBINED LABORATORY ABRASION TEST OF WORKING TOOLS MATERIALS

Researches of wear of agricultural machines working tools, especially soil cutting elements, in field conditions are complicated because of inconstancy of properties of soil mass. The authors developed the method of a research of materials wear with use of two stands. At the IM-01 stand flat grinded samples were tested. Wear was determined by weighing on analytical scales. The second stand (KPS) represented the circular soil canal in which placed the abrasive weight consisting of the particles of clay, sand and other components existing in real soils. Approximate assessment of coefficient of relative wear resistance for two-layer fragments of soil cutting blades was developed. This coefficient can be determined at the rotary soil stand directly only when comparing monometallic fragments of products (by their linear wear). In case of IM-01 stand the coefficient was calculated according to comparative data of weight wear practically for any materials. «Transfer» of laboratory researches results to real conditions of wear is possible only approximately: in practice the difference in the compared results equals 30-35 percent. Laboratory researches by the IM-01 stand were spent in case of loading 4.85 N during 0.5 h for each sample. steel 65G with the hardness of 40±2 HRC was used as a standard, corundum of fraction of 0.2-0.4 mm was as abrasive material. Rotary soil stand testing was carried out at a speed of rotation of the driving mechanism 40 revolutions per minute that corresponded to the speed of movement of samples 2.2 meters per second. The cutting angle of installation to a furrow bottom is similar to this indicator for a ploughshare and equals to 30 degrees. From the chosen materials and hard alloys the best results has taken a basis steel 50KhFA with hard PR-FBYu-1-4 alloy. In comparison with a reference sample, weight wear resistance increased by 2.9 times, and linear one risened by 3.5 times. Use of new materials with the improved characteristics of wear resistance can raise a resource of working tools, in particular ploughshares, by 2.5-3 times, at the same time efficiency by the principle «price - quality» can increase by 2.1 times.