That's why Atomat, since 1996, has introduced its 4-guideways lathes which are best suited for hard-turning of very hard material, as the WC composite rolls. In particular, the grooves opened can be narrower than what is required by the physical copy-template or by the executed CNC program. Old lathes are sometimes not capable of producing a correct geometry with the WC turning, due to the high stress and forces which are involved during such process. Since the dimension of the rolls (which can reach 400mm of diameter and 2,5m of overall length) and since the common presence of many lathes (CNC or conventional) in customer’s rollshop, the first usual attempt to machine the WC rolls is by turning with the use of CBN/PCBN or PCD turning tips. In fact, when comes the time to manage the maintenance of the WC composite rolls, there are several questions and considerations to be made on both the type of machining process and the tooling to use for such a process. Specifically, for the hot rolling mills - bar and rebar mill – the most common grades which can be found among different customers and countries are those with 25-30% of binder, which is the best compromise between roll-performances in the mill and maintainability in the roll shop. Nowadays, more than 70 years later, the range of tungsten carbide grades used for hot and cold rolling mills extends from a 10% to a 30% of binder, which is one of the main parameters, along with grain size, that makes the difference in the selection of a WC grade. This was the start for the use of tungsten carbide (WC) for all kinds of cutting tools and wear parts. For small dimension pieces, the possibility to use the powder metallurgy has been used very quickly in order to obtain very hard and resisting materials. Since the end of the second world war, the economic growth worked together with the continuous search for performing production tools.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |