# US 2009/0260892 A1 · Drill rod, drill bit, and drilling tool > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2009/0260892 A1 - Document ID: US20090260892A1 - Status: Published application - Kind: A1 - Application number: 12/092,134 - Filed: 2006-11-21 - Published: 2009-10-22 - Earliest claimed: 2005-12-09 - Assignees: Mitsubishi Materials Corporation; Furukawa Rock Drill Co., Ltd. - Inventors: Masaya Hisada; Masahiro Koizumi; Takashi Suzuki - Web page: https://patentgrep.com/patent/US20090260892A1 ## CPC - E21B 10/36: Percussion drill bits ({with helical conveying portion E21B10/445;} characterised by wear resisting parts E21B10/46) - E21B 17/042: Threaded - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract A drill rod having a fitting portion protruding toward the distal end and of the drill rod and extending along a first axial line, wherein the fitting portion includes: a parallel male thread portion in which a minimum distance from the first axial line in a cross-section perpendicular to the first axial line is constant; and a male thread ending portion which is continuous with a proximal end of the parallel male thread portion, and in which the minimum distance increases as approaching toward a proximal end thereof; wherein the fitting portion is formed such that the minimum distance does not decrease as approaching from a distal end to a proximal end thereof; and the proximal end of the male thread ending portion is positioned on a face where a distance from the first axial line gradually increases as approaching from the parallel male thread to the proximal end of the male thread ending portion. ## Claims ### Claim 1 A drill rod comprising a fitting portion which protrudes toward a distal end of the drill rod and extends along a first axial line, wherein the fitting portion includes: a parallel male thread portion in which a minimum distance from the first axial line in a cross-section perpendicular to the first axial line is constant; and a male thread ending portion which is continuous with a proximal end of the parallel male thread portion, and in which the minimum distance increases as approaching toward a proximal end thereof, wherein the fitting portion is formed such that the minimum distance does not decrease as approaching from a distal end to a proximal end thereof; and the proximal end of the male thread ending portion is positioned on a face where a distance from the first axial line gradually increases as approaching from the parallel male thread to the proximal end of the male thread ending portion. ### Claim 2 (depends on 1) The drill rod according to claim 1, wherein a radius of curvature of a thread groove portion in the male thread ending portion, in a cross-section including the first axial line, is larger than a radius of curvature of a thread groove portion of a male thread 20 formed in the parallel male thread portion, in a cross-section including the first axial line. ### Claim 3 (depends on 1) The drill rod according to claim 1, wherein a length l1 of the male thread ending portion along the first axial line direction is equal to or less than a thread pitch P of the parallel male thread portion. ### Claim 4 (depends on 1) The drill rod according to claim 1, wherein a length L along the first axial line direction from a distal end face of the fitting portion to the proximal end of the parallel male thread portion, with respect to a diameter D of the thread groove of the parallel male thread portion, satisfies L≦2.5×D; and a length L1 along the first axial line direction of the parallel male thread portion, with respect to a thread pitch P of the parallel male thread portion, satisfies L1≧3.8×P. ### Claim 5 A drill bit comprising a fitting hole which is opened toward a proximal end of the drill bit and extends along a second axial line, wherein the fitting hole includes: a parallel female thread portion in which a maximum distance from the second axial line in a cross-section perpendicular to the second axial line is constant; and a female thread ending portion which is continuous with a distal end of the parallel female thread portion, in which the maximum distance decreases as approaching toward a distal end thereof; the fitting hole is formed such that the maximum distance does not decrease as approaching from a distal end toward the proximal end thereof, and the distal end of the female thread ending portion is positioned on a face where a distance from the second axial line is smaller than that for the parallel female thread portion. ### Claim 6 (depends on 5) The drill bit according to claim 5, wherein a radius of curvature of a thread groove portion in the female thread ending portion, in a cross-section including the second axial line, is larger than a radius of curvature of a thread groove portion of a female thread formed in the parallel female thread portion, in a cross-section including the second axial line. ### Claim 7 (depends on 5) The drill bit according to claim 5, wherein a length l2 of the female thread ending portion along the second axial line direction is equal to or less than a thread pitch P of the parallel female thread portion. ### Claim 8 (depends on 1, 5) A drilling tool comprising the drill rod according to claim 1 and the drill bit according to claim 5, wherein the drilling tool is configured by screwing the parallel male thread portion of the drill rod with the parallel female thread portion of the drill bit. ### Claim 9 (depends on 8) The drilling tool according to claim 8, wherein in a state in which the drill rod and the drill bit are screwed together, a distance along the first axial line direction between a distal end of the parallel male thread portion and a proximal end of the female thread ending portion is greater than a distance along the first axial line direction between a distal end of the male thread ending portion and a proximal end of the parallel female thread portion. ### Claim 10 (depends on 8) The drilling tool according to claim 8, further comprising: a first inclined face formed on the proximal end portion of the fitting portion of the drill rod in which a distance from the first axial line in a cross-section perpendicular to the first axial line gradually increases as approaching toward a proximal end of the drill rod; and a second inclined face formed on a proximal end portion of the fitting hole of the drill bit in which a distance from the second axial line in a cross-section perpendicular to the second axial line gradually increases as approaching toward the proximal end, wherein when the first axial line of the fitting portion and the second axial line of the fitting hole coincide, the first inclined face and the second inclined face are separated, while when the first axial line and the second axial line are displaced so as not to coincide, the first inclined face and the second inclined face are in mutual contact.