METHODS OF WEDGE’S CALORIFIC INTENSITY REDUCTION AT CAR-WHEEL PROCESSING
Background. The technology of car-wheel processing doesn’t stipulate application of lubricant-cooling media (LCM), which significantly increases the temperature of cutting and deteriorates instrument’s durability. Therefore, the article considers the methods instrument’s durability improvement by decreasing the cutting temperature, without LCM application. Relevance of the research is also proved by the trend of ecological cutting “Green cutting” without LCM application. Materials and methods. The research was performed at processing of wheel pairs on Rafamet lathes of UDA-112 series. The research object was lathe tools equipped with removable blades of LNMX 301940 and BNMX (ISO 513) forms, with some of them entering the control group withouth coating and the other being covered with specially designed nanodispersed multilayered composite coatings (NMCC). The authors used cutting blades fixed on holders; between a support blade and a cutting blade there was formed a special interface, improving eat extraction into the cutting tool. During durability tests the criterion of instrument failure was the limiting wear of the rear surface of the cutting blade h 3 = 0,6-0,8 mm. The rear surface’s wear flat was measured by the toolmaker’s microscope BMI-1Ts. Roughness of the processed surface was estimated by the Hand-held Roughness Tester TR 200 (Japan). Results. The authors established high efficiency of hardmetal cutting blades of LNMX 301940 form made of АТ15S alloy with the heat-extracting interface and the developed NMCC on the basis of Ti-TiN-(Ti,Al)N in comparison with standard analogs in conditions of hard reducing turning of wheel pairs. In particular, the researchers pointed out not just a high average durability value (88,1 min) and a durability coefficient (103,12), but also a decrease of the durability variation coefficient (υ = 3,25). The emphasized information indicates a significant increase in operating ability and reliability of the instrument equipped with tangential LNMX 301940 blades of AT15S alloy with improved heat conductivity of the hard metal and coating on the basis of the Ti-TiN-TiAlN system, developed for wheel pairs’ surface turning. Conclusions. The researchers considered the cutting instrument’s heat condition in the process of car-wheel processing that determines its operating ability. The authors suggested the ways to improve heat extraction from the cutting blade during processing. Application thereof allows to decrease calorific intensity of a cutting blade and, accordingly, to increase instrument’s durability at car-wheel processing.