Steel drill bit partially coated with wear resistant material having prolonged service life - has medium alloy steel base, wear resistant layer, hard pin in receiving hole in base

摘要

A (drill) bit or similar tool used for the recovery of raw materials or for recycling comprises: (1) a medium-alloy steel base, the shaft of which is contained in a bit holder, the remainder protruding above the bit holder, compsn. of base being 0.1-0.8% C, 0.1-5.0% Si and max. 20.0% Cr, max. 15.0% Mn, max. 10.0% V, W and Nb and max. 12.0% Ni, with balance Fe plus usual impurities, e.g. S and P; (2) a wear-resistant layer applied by plasma-powder welding to at least part of the steel base protruding above the bit holder, compsn. of said layer being 1.5-8.0% C, 3.0-40.05% Cr, 0.1-30.0% V and Nb, 0.1-60.0% W, max. 8.0% B, 0.1-8.0% Si, 0.1-15.0% Mn and 0.1-8.0% Ni; (3) a hard pin secured in a receiving hole in the steel base. Furthermore, the steel base shaft region (3) rotates freely w.r.t. the bit holder (9) and the wear-resistant layer is applied in the form of strips (8) in such a way that forces applied to the edges of the strips function in a circumferential direction. ADVANTAGE - Bit service life is not curtailed due to uneven wear on the hard pin.