Investigation of contact phenomena in turning using tools made of low-alloy high-speed steels

Abstract

INVESTIGATION OF CONTACT PHENOMENA IN TURNING USING TOOLS MADE OF LOW-ALLOY HIGH-SPEED STEEL Jan Jaworski, Tomasz TrzepiecińskiOriginal scientific paper In this paper, the results of investigations of the temperature field distribution and tool wearing during C60 steel turning are presented. Abrasive wear resistance tests were carried out for cutters made of low-alloy high-speed steel. Steel samples were heat treated, and then were subjected to ion nitriding, TiN coating, or to complex treatment. The influence of cutting speed on the value of basic parameters characterising the phenomena in the tool-workpiece interface i.e., cutting ratio, friction coefficient, and length of contact zone, is analysed. An increase of the rake angle value causes an increase in the value of the friction coefficient. Furthermore, the value of the friction coefficient decreases as the thickness of the cut layer increases. Investigations of the durability of cutting edges confirm that to define the working conditions of the tool, resistance against hardness loss with increasing temperature at temperatures higher and lower than the tempering temperature is the most significant. Keywords: cut layer; cutting ratio; high-speed steels; turning; wear; wear resistance Ispitivanje fenomena dodira kod tokarenja primjenom alata od niskolegiranog brzoreznog čelikaIzvorni znanstveni članak U ovom se radu daju rezultati ispitivanja raspodjele temperaturnog polja i trošenja alata tijekom tokarenja čelika C60. Provedena su ispitivanja otpornosti na abrazivno trošenje tokarskih noževa izrađenih od niskolegiranog brzoreznog čelika. Uzorci čelika su toplinski obrađeni i zatim podvrgnuti ionskom nitriranju, oblaganju TiN ili kompleksnoj obradi. Analiziran je utjecaj brzine rezanja na vrijednost osnovnih parametara karakterističnih za pojave u graničnoj površini alat-obradak, t.j. rezni omjer, faktor trenja i dužina zone dodira. Porast vrijednosti kuta nagiba dovodi do porasta vrijednosti faktora trenja. Nadalje, vrijednost faktora trenja se smanjuje kako raste debljina reznog sloja. Ispitivanja trajnosti rezne oštrice potvrđuju da je u definiranju radnih uvjeta alata, najvažnija otpornost na gubitak tvrdoće kod porasta temperature na temperaturama višim i nižim od temperature popuštanja.