Apparatus for detecting drill bit wear

A rotary cone drill bit, comprising:

• a main bit body having an interior chamber;
• a port in said bit body extending between said interior chamber and the exterior of said bit body;
• a spindle secured to said bit body;
• a cutting element rotatably secured on said spindle;
• a tensioned linkage extending through said spindle and bit body, said tensioned linkage having first and second ends;
• a passageway extending through said spindle and bit body, said tensioned linkage extending through said passageway, said passageway including two passageway segments, said passageway segments intersecting at an angle within said bit;
• a guide element at the intersection between said passageway segments, said guide element defining a curved channel linking said two passageway segments, said guide element being an insert within the bit body;
• a tensioned linkage termination element secured to said tensioned linkage first end, said termination element being supported on said spindle;
• means for twisting said termination element in response to said cone rotating with a predetermined degree of eccentricity, said termination element and tensioned linkage being adapted to part from one another in response to twisting of said termination element;
• and
• means for altering the fluid flow resistance of said port in response to a decrease in the tension of said tensioned linkage, said tensioned linkage second end being secured to said flow resistance altering means.

A rotary cone drill bit. comprising:

• a main bit body having an interior chamber;
• a port in said bit body extending between said interior chamber and the exterior of said bit body;
• a spindle secured to said bit body;
• a rotatable cutting element on said spindle;
• a tensioned linkage extending through said spindle and bit body, said tensioned linkage having first and second ends;
• a passageway extending through said spindle and bit body, said tensioned linkage being situated within said passageway, said passageway including two passageway segments, said passageway segments intersecting at an angle within said bit;
• a guide element at the intersection between said passageway segments, said guide element defining a curved channel linking said two passageway segments;
• a tensioned linkage termination element secured to said tensioned linkage first end, said termination element being supported on said spindle;
• means for causing said termination element and tensioned linkage to part from one another in response to said cone moving a prescheduled distance axially outward from an initial position on said spindle;
• and
• means for altering the flow resistance of said port in response to a decrease in the tension of said tensioned linkage, said tensioned linkage second end being secured to said flow resistance altering means.

A rotary cone drill bit, comprising:

• a main bit body having an interior chamber;
• a port in said bit body extending between said interior chamber and the exterior of said bit body;
• a spindle secured to said bit body;
• a rotatable cutting element on said spindle;
• a tensioned linkage extending through said spindle and bit body, said tensioned linkage having first and second ends;
• a tensioned linkage termination element secured to said tensioned linkage first end, said termination element being supported on said spindle;
• means for causing said termination element and tensioned linkage to part from one another in response to said cone moving a prescheduled distance axially outward from an initial position on said spindle;
• and
• means for altering the fluid flow resistance of said port in response to a decrease in the tension of said tensioned linkage, said tensioned linkage second end being secured to said flow resistance altering means.

A drill bit, comprising:

• a main bit body defining a central chamber;
• at least one port in said main bit body establishing a fluid pathway between said central chamber and the exterior of said main bit body;
• a sensor connected to a selected location on said drill bit to detect wear of said drill bit proximate said selected location;
• a blocking element within said main bit body, said blocking element being adapted to at least partially block fluid flow through said port in response to said blocking element being released within said main bit body, said blocking element defining a slot extending therethrough;
• means for releasably retaining said blocking element at an initial position within said bit body, said retaining means including a retainer;
• and
• a tensioned linkage connected between said wear sensor and said retainer element, said tensioned linkage extending through the slot in said blocking element, whereby on relieving the tension on said tensioned linkage, said blocking element will fall away from said tensioned linkage.