Tool joint

A tool joint having an axis A and comprising a male member and a female member;

• the male member having an axis B and comprising:
• a male body portion;
• and
• a male coupling portion projecting rearwardly from the male body portion, the male coupling portion having an unthreaded forward portion adjacent the male body portion and a rear threaded portion terminating at a rear end;
• the threaded portion of the male coupling portion having a thread terminating in a forward end part adjacent the forward portion of the male coupling portion and in a rear end part adjacent the rear end of the rear portion of the male coupling portion, the thread having an intermediate section of uniform depth between the forward and rear end parts;
• the forward end part of the thread of the male coupling portion being a thread root having a variable depth gradually decreasing from a depth equal to the uniform depth of the thread to no depth;
• the rear end part of the thread of the male coupling portion being a tread crest having a variables height gradually decreasing from a height equal to the uniform depth of the thread to no height;
• the female member having an axis C and comprising:
• a female body portion;
• and
• a female coupling portion comprising a bore for accepting the male coupling portion, the bore extending rearwardly from a front surface of the female member towards the female body portion, the bore having an unthreaded forward portion adjacent the front surface and a rear threaded portion terminating adjacent the female body portion;
• the threaded portion of the female coupling portion having a thread terminating in a forward end part adjacent the unthreaded forward portion of the female coupling portion and in a rear end part adjacent the female body portion, the thread of the female coupling portion having an intermediate section between the forward and rear end parts, the thread of the intermediate section of the female coupling portion having a depth equal to the uniform depth;
• the forward end part of the thread of the female coupling portion being a thread crest having a variable height gradually decreasing from a height equal to the uniform depth to no height;
• the rear end part of the thread of the female coupling portion being a thread root having a variable depth decreasing from a depth equal to the uniform depth of the thread to no depth;
• wherein, upon threaded coupling of the male and female members to form a tool joint connection, the threaded portion of the male member engages the threaded portion of the female member.

A male member for a tool joint having an axis B and comprising:

• a male body portion;
• and
• a male coupling portion projecting rearwardly from the male body portion, the male coupling portion having an unthreaded forward portion adjacent the male body portion and a rear threaded portion terminating at a rear end;
• the rear threaded portion having a thread terminating in a forward end part adjacent the forward portion and in a rear end part adjacent the rear end of the rear portion, the thread having an intermediate section of uniform depth between the forward and rear end parts;
• the forward end part of the thread being a thread root having a variable depth gradually decreasing from a depth equal to the uniform depth to no depth;
• the rear end part of the thread being a thread crest having a variable height gradually decreasing from a height equal to the uniform depth to no height.

A female member for a tool joint having an axis C and comprising:

• a female body portion;
• and
• a female coupling portion comprising a bore extending rearwardly from a front surface towards the female body portion, the bore having an unthreaded forward portion adjacent the front surface and a rear threaded portion terminating adjacent the female body portion;
• the threaded portion having a thread terminating in a forward end part adjacent the unthreaded forward portion and in a rear end part adjacent the female body portion, the thread having an intermediate second between the forward and rear end parts, the thread of the intermediate section having a depth equal to the uniform depth;
• the forward end part of the thread being a thread crest having a variable height gradually decreasing from a height equal to the uniform depth to no height;
• the rear end part of the thread being a thread root having a variable depth decreasing from a depth equal to the uniform depth.

A cutting tool assembly comprising a cutting head screw-coupled to a tool shank, wherein:

• the cutting head comprises:
• a rearwardly projecting coupling portion, the coupling portion having an unthreaded forward portion and a rear threaded portion terminating at a rear end;
• the rear threaded portion having a thread terminating in a forward end part adjacent the forward portion and in a rear end part adjacent the rear end, the thread having an intermediate section of uniform depth between the forward and rear end parts;
• the forward end part being a thread root having a variable depth gradually decreasing from a depth equal to the uniform depth of the thread to no depth;
• the rear end part being a thread crest having a variable height gradually decreasing from a height equal to the uniform depth of the thread to no height;
• and
• the tool shank comprises:
• a bore extending rearwardly from a front surface of the tool shank, the bore having an unthreaded forward portion adjacent the front surface and a rear threaded portion terminating adjacent a rear end of the bore;
• the threaded portion having a thread terminating in a forward end part adjacent the unthreaded forward portion and in a rear part adjacent the rear end, the thread having an intermediate section of uniform depth between the forward and rear end parts;
• the forward end part of the thread being a thread crest having a variable height gradually decreasing from a height equal to the uniform depth to no height;
• the rear end part of the thread being a thread root having a variable depth decreasing from depth equal to the uniform depth of the thread to no depth.

A cutting head having an rearwardly projecting coupling portion,

• the coupling porting having an unthreaded forward portion and a rear threaded portion terminating at a rear end;
• the threaded portion having a thread terminating in a forward end part adjacent the forward portion and in a rear end part adjacent the rear end, the thread having an intermediate section of uniform depth between the forward and rear end parts;
• the forward end part being a thread root having a variable depth gradually decreasing from a depth equal to the uniform depth of the thread to no depth;
• the rear end part being a thread crest having a variable height gradually decreasing from a height equal to the uniform depth of the thread to no height.