A thread forming tool for forming an internal thread in a workpiece includes a shank and a thread forming portion, which are rotatable around a common longitudinal axis. The thread forming portion includes a plurality of radially protruding lobe portions that are circumferentially spaced-apart by relief portions. The lobe portions have, in the longitudinal direction, a plurality of thread forming profiles and in the longitudinal direction a plurality of thread grooves. Each thread forming profile includes a radially outermost ridge connected to a first flank and a second flank, wherein a first flank of a first thread forming profile is connected to a second flank of an adjacent second thread forming profile via a thread groove. The flanks of at least one first thread groove enclose a first angle, which is smaller than a second angle enclosed by the flanks of at least one second thread groove.

A thread forming tool for forming an internal thread in a workpiece includes a shank and a thread forming portion, which are rotatable around a common longitudinal axis. The thread forming portion includes a plurality of radially protruding lobe portions that are circumferentially spaced-apart by relief portions. The lobe portions have, in the longitudinal direction, a plurality of thread forming profiles and in the longitudinal direction a plurality of thread grooves. Each thread forming profile includes a radially outermost ridge connected to a first flank and a second flank, wherein a first flank of a first thread forming profile is connected to a second flank of an adjacent second thread forming profile via a thread groove. The flanks of at least one first thread groove enclose a first angle, which is smaller than a second angle enclosed by the flanks of at least one second thread groove.

A tool for producing an internal thread in a workpiece pilot hole having a thread major diameter and a thread minor diameter, which tool has a thread-forming section, by which an internal thread profile can be produced in a pilot hole wall. The internal thread profile having the thread major diameter and a thread inner diameter. The tool has a drilling section, by which the thread inner diameter of the internal thread profile can be expanded to the thread minor diameter by machining. At least one, in particular exactly one chip groove is associated with the drilling section of the tool, by which chip groove the chips produced as the thread inner diameter is expanded to the thread minor diameter can be transported away.

A tool for producing an internal thread in a workpiece pilot hole having a thread major diameter and a thread minor diameter, which tool has a thread-forming section, by which an internal thread profile can be produced in a pilot hole wall. The internal thread profile having the thread major diameter and a thread inner diameter. The tool has a drilling section, by which the thread inner diameter of the internal thread profile can be expanded to the thread minor diameter by machining. At least one, in particular exactly one chip groove is associated with the drilling section of the tool, by which chip groove the chips produced as the thread inner diameter is expanded to the thread minor diameter can be transported away.

A thread forming tap includes a partial thread. The partial thread is provided, in the axis direction view, with a protrusion formed so as to protrude in the radial direction and a clearance section formed so as to have a smaller diameter than the protrusion, and as a result of the foregoing, if a thread forming tap rotates in a state where the inner circumferential surface of a pilot hole and the partial thread come into contact, the protrusion of the partial thread can be caused to engage with the inner circumferential surface of the pilot hole. Due to this configuration, rubbing in a state where the partial thread is pressed against the inner circumferential surface of the pilot hole can be suppressed, and as a result, chipping of the partial thread can be prevented.

A thread former for the chipless production of a thread has a plurality of pressing lands, which are each arranged at predefined separation angles (T) along a shaping curve. Each separation angle (T) is smaller than or equal to a predefined maximum separation angle (T.sub.max). For nominal thread former diameters (Da) between 6 mm and 20 mm, the maximum separation angle (T.sub.max) is determined such that the following condition: T.sub.max=sin.sup.1((aND.sup.y+bND+c)2); is met for i) 6ND<10 where a=0.0008, b=0.00705, c=0.1325, y=2; ii) 10ND<12 where a=1.7924/(2), b=0, c=0, y=0.408; or iii) 12ND20 where a=0.751/(2), b=0, c=0, y=0.104; wherein T.sub.max is the maximum separation angle and ND is the amount of the nominal thread former diameter (Da) measured in millimeters.

A thread former for the chipless production of a thread has a plurality of pressing lands, which are each arranged at predefined separation angles (T) along a shaping curve. Each separation angle (T) is smaller than or equal to a predefined maximum separation angle (T.sub.max). For nominal thread former diameters (Da) between 6 mm and 20 mm, the maximum separation angle (T.sub.max) is determined such that the following condition: T.sub.max=sin.sup.1((aND.sup.y+bND+c)2); is met for i) 6ND<10 where a=0.0008, b=0.00705, c=0.1325, y=2; ii) 10ND<12 where a=1.7924/(2), b=0, c=0, y=0.408; or iii) 12ND20 where a=0.751/(2), b=0, c=0, y=0.104; wherein T.sub.max is the maximum separation angle and ND is the amount of the nominal thread former diameter (Da) measured in millimeters.

A thread forming tap including a complete thread portion and a leading portion that are provided with an external thread. A thread ridge of the external thread has, in an axial cross section, a triangular shape that is defined by a pair of flanks located on respective opposite sides in an axial direction, such that each of the flanks is inclined by a predetermined flank angle corresponding to a shape of a valley of an internal thread to be formed. A sharp crest is provided in a top portion of the thread ridge at least in the leading portion, and has, in the axial cross section, a triangular shape that is defined by a pair of side surfaces located on respective opposite sides in the axial direction, such that each of the side surfaces is inclined by an inclination angle that is larger than the flank angle.

A thread forming tap including a complete thread portion and a leading portion that are provided with an external thread. A thread ridge of the external thread has, in an axial cross section, a triangular shape that is defined by a pair of flanks located on respective opposite sides in an axial direction, such that each of the flanks is inclined by a predetermined flank angle corresponding to a shape of a valley of an internal thread to be formed. A sharp crest is provided in a top portion of the thread ridge at least in the leading portion, and has, in the axial cross section, a triangular shape that is defined by a pair of side surfaces located on respective opposite sides in the axial direction, such that each of the side surfaces is inclined by an inclination angle that is larger than the flank angle.

A tool for producing an internal thread in a workpiece pilot hole having a thread major diameter and a thread minor diameter, which tool has a thread-forming section, by which an internal thread profile can be produced in a pilot hole wall. The internal thread profile having the thread major diameter and a thread inner diameter. The tool has a drilling section, by which the thread inner diameter of the internal thread profile can be expanded to the thread minor diameter by machining. At least one, in particular exactly one chip groove is associated with the drilling section of the tool, by which chip groove the chips produced as the thread inner diameter is expanded to the thread minor diameter can be transported away.