A hybrid bit includes an earth-boring element and a percussion element. The earth-boring element and the percussion element are coaxially arranged, with the earth-boring element surrounding the percussion element. A reciprocating member of the percussion element may oscillate in a manner that enables a bottom end of the reciprocating member to repeatedly protrude from a bottom end of the earth-boring element and to be repeatedly withdrawn. A configuration of the earth-boring element may enable it to drill into and remove some materials from an earth formation, while the percussion element may enable the hybrid bit to drill into and remove difficult-to-drill materials, including abrasive materials and/or materials with high compressive forces, such as chert.

A hybrid bit includes an earth-boring element and a percussion element. The earth-boring element and the percussion element are coaxially arranged, with the earth-boring element surrounding the percussion element. A reciprocating member of the percussion element may oscillate in a manner that enables a bottom end of the reciprocating member to repeatedly protrude from a bottom end of the earth-boring element and to be repeatedly withdrawn. A configuration of the earth-boring element may enable it to drill into and remove some materials from an earth formation, while the percussion element may enable the hybrid bit to drill into and remove difficult-to-drill materials, including abrasive materials and/or materials with high compressive forces, such as chert.

A ground drilling device comprising a housing, a lengthwise movable drilling head tip arranged in the housing, and a bearing for supporting the drilling head tip in the housing during its lengthwise movement.

An apparatus for boring a wellbore, including a bit body having a first end, an inner cavity, and a second end. The first end is connected to a workstring that is configured to deliver a rotational force to the bit body. The inner cavity contains a profile having a first radial cam surface. The second end includes a working face containing a cutting member. The apparatus also includes a pilot bit rotatively connected within the inner cavity. A second radial cam surface is contained on a first end of the pilot bit. The first and second radial cam surfaces are operatively configured to deliver a hammering force. A second end of the pilot bit may include an engaging surface configured to engage a formation surrounding the wellbore. The bit body rotates relative to the pilot bit.

An apparatus for boring a wellbore, including a bit body having a first end, an inner cavity, and a second end. The first end is connected to a workstring that is configured to deliver a rotational force to the bit body. The inner cavity contains a profile having a first radial cam surface. The second end includes a working face containing a cutting member. The apparatus also includes a pilot bit rotatively connected within the inner cavity. A second radial cam surface is contained on a first end of the pilot bit. The first and second radial cam surfaces are operatively configured to deliver a hammering force. A second end of the pilot bit may include an engaging surface configured to engage a formation surrounding the wellbore. The bit body rotates relative to the pilot bit.

The present invention relates to a downhole tool for removing a restriction in a well tubular metal structure having a wall and an inner diameter, the restriction partly blocking the inner diameter, creating an opening defined at least partly by a rim section of the restriction, the downhole tool having a tool axis and comprising a tool body having a first part and a second part, an electrical motor arranged in the first part for rotating a rotatable shaft, a core bit arranged in the second part and having a first end connected with the rotatable shaft and a second end having a cutting edge, wherein the second part of the downhole tool further comprises a locator for locating the rim section, a collecting means for collecting part of the restriction to be cut out by the cutting edge, the locator and the collecting means are rotating with the core bit until the locator locates the rim section and a threshold value is reached.

The present invention relates to a downhole tool for removing a restriction in a well tubular metal structure having a wall and an inner diameter, the restriction partly blocking the inner diameter, creating an opening defined at least partly by a rim section of the restriction, the downhole tool having a tool axis and comprising a tool body having a first part and a second part, an electrical motor arranged in the first part for rotating a rotatable shaft, a core bit arranged in the second part and having a first end connected with the rotatable shaft and a second end having a cutting edge, wherein the second part of the downhole tool further comprises a locator for locating the rim section, a collecting means for collecting part of the restriction to be cut out by the cutting edge, the locator and the collecting means are rotating with the core bit until the locator locates the rim section and a threshold value is reached.

A constant velocity joint for downhole power transmission has a first insert mounted in a radially extending drive shaft arm. The first insert engages a second insert mounted along a slot formed in a tubular housing disposed to receive the arm. The material for the two inserts may be different, having different galling properties. An insert may be shaped to have at least a flat surface, a cylindrical surface intersecting the flat surface, and a conical surface intersecting the cylindrical surface. The inserts may extend beyond the cavities in which they are mounted. Opposing cavity walls adjacent the cavity opening may be angled away from one another to permit the insert to flex under a load. The back wall of a cavity and back surface of an insert may be arcuate to permit rotational movement of the insert under a load.

A constant velocity joint for downhole power transmission has a first insert mounted in a radially extending drive shaft arm. The first insert engages a second insert mounted along a slot formed in a tubular housing disposed to receive the arm. The material for the two inserts may be different, having different galling properties. An insert may be shaped to have at least a flat surface, a cylindrical surface intersecting the flat surface, and a conical surface intersecting the cylindrical surface. The inserts may extend beyond the cavities in which they are mounted. Opposing cavity walls adjacent the cavity opening may be angled away from one another to permit the insert to flex under a load. The back wall of a cavity and back surface of an insert may be arcuate to permit rotational movement of the insert under a load.

A downhole tool, for removing a restriction in a well tubular metal structure having a wall and an inner diameter, has a tool axis and a tool body having a first part and a second part, an electrical motor arranged in the first part for rotating a rotatable shaft, and a core bit arranged in the second part and having a first end connected with the rotatable shaft and a second end having a cutting edge. The second part of the downhole tool further includes a locator for locating the rim section, the locator being rotable with the core bit until the locator locates the rim section and a threshold value is reached.