Sandvik Ab

Lars-Gunnar Lundell

Johan Lind&eacute;n

A percussive rock drill bit includes a head portion with a forward surface surrounded by a peripheral surface. The peripheral surface supports a wreath of peripheral buttons. Front buttons are mounted to the forward surface inside the wreath of peripheral buttons. The button shave a diameter (D) and a height (H), wherein H/D<1.2. The buttons are welded to an essentially flat part of the forward surface whereby the buttons are metallurgically bound to the head portion.

Percussive rock drill bit and buttons therefor and method for manufacturing drill bit

The present invention relates to a martensitic, corrosion resistant steel for rock drilling with properties which is adjusted essentially with regard to resistance against corrosion fatigue. This has been obtained in that an elongated element for percussive rock drilling which includes at least a thread and a flush channel has been made with corrosion resistant steel having a mainly martensitic structure.

Elongated percussive rock drilling element

A metallic drilling member is surface hardened except at an end portion, because the end portion is masked. The masking is achieved by placing on the end portion a lid which forms a slight gap around the surface being heat treated. During the heat treatment a furnace atmosphere enters the gap to cause the depth of the heat treatment to be gradually decreased in a manner producing a relatively elongated transition zone between heat treated and non-heat treated portions of the surface. The gap can be of constant width, or gradually decreasing width.

Methods and apparatus for masking a percussive drill member prior to a surface treatment thereof

A drill bit has a plurality of cemented carbide buttons embedded in a front end of the drill body. Each button includes a cemented carbide body having a rear mounting portion embedded in the drill body, and a symmetrically shaped crushing end protruding from the drill body. The buttons are oriented at a first acute angle of from about 35&deg; to about 55&deg; relative to the rotational center axis of the drill bit. The crushing end of the button includes at least one annular groove defining axially spaced local maximum points at each side of the groove. An imaginary line touching the maximum points defining a second acute angle relative to the center line of the button. The second angle is smaller than the first acute angle.

Drill bit and button

A rock drilling rod is manufactured by placing free ends of first and second hollow rod components in abutment, and establishing relative rotation between the free ends to friction weld those free ends together. The first component comprises a thread and a clearance portion disposed adjacent the thread. The first component has a hot hardness value of at least about 170 HV1 at 600.degree. C. Prior to friction welding the components together, the thread, clearance portion and central passage of the first component are heat treated against corrosion fatigue. Then, the thread is high frequency hardened to a depth at least as great as the heat treated layer. Following the welding, the weld is cooled while keeping a core hardness of the respective portions of the first and second components disposed immediately adjacent the weld no lower than 390 HV1.

Drill rod and method for its manufacturer

A rock drilling rod is manufactured by placing free ends of first and second hollow rod components in abutment, and establishing relative rotation between the free ends to friction weld those free ends together. The first component comprises a thread and a clearance portion disposed adjacent the thread. The first component has a hot hardness value of at least about 170 HV1 at 600.degree. C. Prior to friction welding the components together, the thread, clearance portion and central passage of the first component are nitrocarburized against corrosion fatigue. Following the nitrocarburizing, the core hardness is at least 440 HV1. Following the welding, the weld is cooled while keeping a core hardness of the respective portions of the first and second components disposed immediately adjacent the weld no lower than 390 HV1.

Drill rod and method for its manufacture

A rock drill bit for percussive drilling includes a steel body in which six gauge buttons and a single front button are mounted. The gauge buttons are arranged symmetrically and equally spaced about a central axis of the bit. The front button is arranged along the central axis. The front button is of larger diameter than the gauge button. At least three of the gauge buttons are diamond-enhanced, and the front button may be diamond-enhanced.

Diamond enhanced rock drill bit for percussive drilling

A friction welded product for rock drilling and method for manufacturing thereof, the product including a first component (25) and a second component (22) of parent material joined by a friction weld (27). The components have a central inner passage (26) and both components are made from a steel having a chemical composition such that the hardness in the most tempered part of the heat affected zone close to the weld is at least the same as that of the core hardness of the rod. Further, the product exhibits normal hardness when cooled to room temperature subsequent to the friction welding thereby having a minimum core hardness at the heat affected zone above 390 HV1.

Friction welded product and method for manufacturing thereof

The present invention relates to a drill rod for percussion drilling machine comprising a rod or a sleeve-shaped element that is provided with a threaded portion for engagement with another correspondingly threaded drill rod element. In order to reduce the risk for pitting damage, the threaded portion is provided with a wear lining that is metallurgically bonded to the rod. The lining is made of a metallic material that is softer than the material of the element, the latter usually being steel.

Drill rod for percussion drilling

A drill bit of the percussion type includes a bit body of steel, a front portion of which is provided with at least one slot in which an insert is attached by brazing. Brazed between the insert and side walls of the slot are side plates which are of uniform thickness while being thinner than the insert. The side plates are formed of cemented carbide or a metal alloy with a coefficient of linear expansion which for temperatures below 500.degree. C. is substantially smaller than that of steel and the braze metal while being approximately the same as that of the insert.

Drill bit with cemented carbide inserts

The present invention relates to a drill rod for percussion drilling machines comprising a rod or a sleeve-shaped element that is provided with a threaded portion for engagement with another correspondingly threaded drill rod element. In order to reduce the risk for pitting damage, the threaded portion is provided with a wear lining that is metallurgically bonded to the rod. The lining is made of a metallic material that is softer than the material of the element, the latter usually being steel.

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Sandviken, Sweden

Lars-Gunnar Lundell