Atlas Copco Secoroc Ab

Mattias Rehnström

Göran Stenberg

Jimmy Carlsson

Drill bit () for a rock drilling tool (), and a method of increasing the toughness of the drill bit, which drill bit () has a drilling surface () that contacts rock during drilling. A longitudinal cross section () of the drill bit () through the drilling surface () exhibits certain relationships of Ltot(depth)/Ltot(5.0) and H(depth)/H(5.0) at the specified depths, along the drill bit's longitudinal axial center line (C) if the drill bit has a length (L) of 10 mm or greater, and Ltot(depth)/Ltot(3.5) and H(depth)/H(3.5) at the specified depths, if the drill bit has a length (L) of 10 mm or less.

Drill bit for a rock drilling tool with increased toughness and method for increasing the toughness of such drill bits

Drill bit () for a rock drilling tool (), which drill bit () has a drilling surface () that contacts rock during drilling. A longitudinal cross section () of the drill bit () through the drilling surface () exhibits the following relationships of Ltot(depth)/Ltot(5.0) and H(depth)/H(5.0) at the specied depths, where H(depth)/H(5.0) is measured according to a Vickers test and Ltot(depth)/Ltot(5.0) is measured according to the Palmqvist method, described in this document substantially along the drill bit's longitudinal axial center line (C): (table (I)). If the drill bit () has en length (L) of 10 mm or greater, and a longitudinal cross section () of the drill bit () through the drilling surface () exhibits the following relationships of Ltot(depth)/Ltot(3.5) and H(depth)/H(3.5) at the specified depths, where H(depth)/H(3.5) is measured according to a Vickers test and Ltot(depth)/Ltot(3.5) is measured according to the Palmqvist method described in this document, substantially along the drill bit's longitudinal axial center line (C): (table (II)). If the drill bit () has en length (L) less than 10 mm.

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Fagersta, Sweden

Mattias Rehnström