Thread generating tool for producing a thread in a workpiece

A thread generating tool for producing a thread in a workpiece, having the features:

• a) the tool is rotatable about a tool axis (A),
• b) the tool has a number n≧1 of groove generating regions for generating in each case one groove in the workpiece and a number m≧1 of thread generating regions for generating the thread in the workpiece,
• c) each of the m thread generating regions is arranged behind one of the n groove generating regions as viewed in an axial projection parallel to the tool axis (A), and has a smaller extent than said groove generating region as viewed in cross section in the axial projection,
• d) wherein at least some of the n groove generating regions are formed as groove generating regions which operate by plastic deformation or impression of the workpiece material,
• e) each groove generating region has a shaping spine which runs substantially in a circumferential direction around the tool axis (A) and which, as viewed in an axial direction, is the radially highest elevation of the groove generating region or projects radially furthest outward,
• f) in front of the shaping spine in an axial direction, each groove generating region has a front surface,
• g) wherein the front surface rises in an axial direction from a front profile, which is situated radially further inward than the shaping spine to the shaping spine,
• h) the front surface forming a run-on surface by means of which the groove generating region presses into the workpiece surface for the first time and with slowly increasing deformation force,
• i) wherein behind the shaping spine in an axial direction, each groove generating region has a back surface which slopes downward from the shaping spine in an axial direction and provides a free space for the flows of workpiece material.

A method for producing a thread in a blind hole in a workpiece, comprising the following method steps:

• generating a number n of grooves in a wall, which encircles a thread axis, of the workpiece by means of n groove generating regions of a tool and by means of a movement of the tool substantially axial with respect to the thread axis, wherein each groove generating region of the tool generates an associated groove;
• introducing thread generating regions, which are situated behind the groove generating regions, of the tool into the generated associated grooves in the wall of the workpiece in a direction along the associated groove,
• generating the thread in each wall sub-region, adjoining the groove(s), of the wall of the workpiece by rotating the tool about the thread axis and with a simultaneous axial feed motion of the thread generating tool coaxially with respect to the thread axis with an axial feed speed adapted to the rotational speed of the rotational movement and to the thread pitch, wherein, during the rotation and the simultaneous axial feed movement, each thread generating region engages into the associated wall sub-region and generates an associated part of a thread flight, and after the rotation projects into the same groove again or into another groove in the wall;
• moving the thread generating regions of the thread generating tool out of the associated grooves in a direction along the grooves,
• wherein a tool is used to perform the method, the tool comprising a thread generating tool for producing a thread in a workpiece, the tool having the following features:
• a) the tool is rotatable about a tool axis (A);
• b) the tool has a number n≧1 of groove generating regions for generating in each case one groove in the workpiece and a number m≧1 of thread generating regions for generating the thread in the workpiece;
• c) each of the m thread generating regions is arranged behind one of the n groove generating regions as viewed in an axial projection parallel to the tool axis (A), and has a smaller extent than said groove generating region as viewed in cross section in the axial projection;
• d) wherein at least some of the n groove generating regions are formed as cutting groove generating regions with groove generating cutting edges;
• e) wherein each groove generating region has a groove cutting edge oriented toward or situated on the face side;
• f) wherein the groove cutting edges are the radially furthest outward projecting regions of the tool, at least in the front portion thereof;
• g) wherein the or each groove cutting edge is adjoined laterally in a circumferential direction by a side cutting edge, which is at the front in the direction of rotation (S) about the tool axis (A);
• and
• h) wherein during the rotation of the tool in the direction of rotation (S) which takes place for the generation of the thread, the front side cutting edge cuts laterally into the workpiece.

A method for producing a thread in a blind hole in a workpiece, comprising the following method steps:

• generating a number n of grooves in a wall, which encircles a thread axis, of the workpiece by means of n groove generating regions of a tool and by means of a movement of the tool substantially axial with respect to the thread axis, wherein each groove generating region of the tool generates an associated groove;
• introducing thread generating regions, which are situated behind the groove generating regions, of the tool into the generated associated grooves in the wall of the workpiece in a direction along the associated groove,
• generating the thread in each wall sub-region, adjoining the groove(s), of the wall of the workpiece by rotating the tool about the thread axis and with a simultaneous axial feed motion of the thread generating tool coaxially with respect to the thread axis with an axial feed speed adapted to the rotational speed of the rotational movement and to the thread pitch, wherein, during the rotation and the simultaneous axial feed movement, each thread generating region engages into the associated wall sub-region and generates an associated part of a thread flight, and after the rotation projects into the same groove again or into another groove in the wall;
• moving the thread generating regions of the thread generating tool out of the associated grooves in a direction along the grooves,
• wherein a tool comprising a thread generating tool is used to perform the above method steps, the tool having the following features:
• a) the tool is rotatable about a tool axis (A),
• b) the tool has a number n≧1 of groove generating regions for generating in each case one groove in the workpiece and a number m≧1 of thread generating regions for generating the thread in the workpiece,
• c) each of the m thread generating regions is arranged behind one of the n groove generating regions as viewed in an axial projection parallel to the tool axis (A), and has a smaller extent than said groove generating region as viewed in cross section in the axial projection,
• d) wherein at least some of the n groove generating regions are formed as groove generating regions which operate by plastic deformation or impression of the workpiece material,
• e) each groove generating region has a shaping spine which runs substantially in a circumferential direction around the tool axis (A) and which, as viewed in an axial direction, is the radially highest elevation of the groove generating region or projects radially furthest outward,
• f) in front of the shaping spine in an axial direction, each groove generating region has a front surface,
• g) wherein the front surface rises in an axial direction from a front profile, which is situated radially further inward than the shaping spine to the shaping spine,
• h) the front surface forming a run-on surface by means of which the groove generating region presses into the workpiece surface for the first time and with slowly increasing deformation force;
• i) wherein behind the shaping spine in an axial direction, each groove generating region has a back surface which slopes downward from the shaping spine in an axial direction and provides a free space for the flows of workpiece material.