Low stress cavity exit for conically connecting drill bit

EP4222337B1Active Publication Date: 2025-09-10SANDVIK MINING & CONSTR TOOLS AB
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Patent Information

Application Number
EP2021786207
Authority / Receiving Office
EP · EP
Patent Type
Patents
Current Assignee / Owner
Priority Date
2020-09-30
Filing Date
2021-09-30
Publication Date
2025-09-10
Estimated Expiration
2041-09-30

AI Technical Summary

Technical Problem

High stress concentrations at the exit of the conical cavity in drill bits lead to increased risk of fracture, which reduces the lifetime and stability of the connection between the drill bit and drill rod in percussive drilling.

Method used

A percussive drill bit design featuring a sleeve section with a transition section that includes multiple curved regions with varying radii and distances from the axial end, reducing stress concentrations by maintaining a secure connection.

Benefits of technology

The design effectively reduces stress at the exit of the conical cavity, enhancing the drill bit's lifetime and preventing detachment or spinning, thereby improving the connection's reliability.

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Abstract

A percussive drill bit comprising a sleeve section and bit section having a longitudinal axis; wherein the sleeve section has an axial end at the opposing end of the drill bit compared to the bit section from which a generally conically shaped internal cavity extends from for receiving a conically shaped drill rod to form a conical frictional connection; characterised in that: the internal cavity has a transition section extending between the axial end of the drill bit and the a straight tapered region; wherein the transition section has at a first curved region having a first radius,TR1, wherein its tangent, TT, to a central point along the first curved transition section is positioned at a first distance, TD1 from the axial end.
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Citation Information

Patent Citations

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    US20070175671A1

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    GB2307930A

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    GB658631A

  • Percussion tool with replaceable point

    US3336081A