Improvement of Working Capacity of Carbide Tools for Machining Rail Wheel Pairs

Abstract

It was found out that under turning wheel pairs, complete tool failure occurs as a result of ductile fracture of cutting wedge. It was also found out that the process of ductile fracture of a tool is governed by creep of local volumes of tool material adjacent to tool contact areas caused by its severe thermo-mechanical load in machining of hard-drawn surfaces of wheel pairs. The method was proposed to effectively reduce thermo-mechanical load on tool contact areas under machining of wheel pairs, while improving heat transfer from the cutting zone, which provides reduction of thermal stress of cutting wedge and improvement of the efficiency of cutting tool.

Main Ways to Improve Cutting Tools for Machine Wheel Tread Profile

“…However, prior to the formation of a new layer of thermally conductive interface, the old paste should be removed with a detergent, and the surfaces should be completely degreased and dried. The above shows the great technological effectiveness of use of thermally conductive paste in production environment [2]. The studies have shown that the use of thermally conductive paste in composite cutter improves heat transfer from the cutting zone and reduces the thermal stress of tool cutting wedge.…”

“…The analysis proved high efficiency of carbide cutting inserts in the form LNMX made of carbide grade WC-TiC-Co with thermally conductive interface and developed NMCC on the basis of a three-layer system of Ti-TiN-(Ti,Al)N in comparison with standard analogues under severe reductive turning of running surface of wheel pairs. In particular, the analysis notes not only the higher average value of lifetime of carbide tool (88.1 min) and the lifetime coefficient CLT(2.10), but also Average tool life of one insert with eight cutting edges for carbide inserts type LNUX 301940, carbide AT15S [19] (process parameters: v = 50 m/min, f and = 1.2 mm/rev, and ap = 6.0 mm) [2].…”

“…Edge machining of workpieces under the above conditions produces elevated heating of the cutting area (up to 800-1000°C), which results in high concentration of thermal stresses directly at the contact areas of carbide inserts (for example, inserts of LNMX ISO shape) used in this process of manufacturing products for rail transport [2][3][4][5][6][7]. The studies of wear mechanisms of cutting carbide inserts with coatings of various compositions have shown [3,[9][10][11][12][13][14][15][16] that the process of wear of inserts under conditions of the high thermal stresses is accompanied by thermoplastic deformation of a cutting edge.…”

“…Main Ways to Improve Cutting Tools for Machine Wheel Tread Profile DOI: http://dx.doi.org/10.5772/intechopen.80302 reduction of the factor of a variation of lifetime (υ LT = 0.35). This indicates the significant increase in working efficiency and reliability of the tool equipped with tangential carbide inserts LNMX made of WC-TiC-Co with enhanced thermal conductivity of carbide with elaborated NMCC on the basis of the system Ti-TiN-TiAlN developed for reductive turning (roughing) of hardened (hard-drawn) surface of wheel pairs [2].…”

“…• inclusion of nonmetallic particles with increased abrasive properties on the machined surface of forged slab [2][3][4].…”