WO2021052835A1

WO2021052835A1 - Method for creating a thread with a predefined thread pitch in a preformed tap hole in a workpiece

Info

Publication number: WO2021052835A1
Application number: PCT/EP2020/075199
Authority: WO
Inventors: Dietmar Hechtle; Thomas Funk; Julian Krause; Jürgen Lange; Christian Beer
Original assignee: EMUGE-Werk Richard Glimpel GmbH & Co. KG Fabrik für Präzisionswerkzeuge
Priority date: 2019-09-16
Filing date: 2020-09-09
Publication date: 2021-03-25
Also published as: DE102019124800A1

Abstract

The invention relates to a method for creating a thread with a predefined thread pitch in a preformed tap hole in a workpiece, wherein: a) a tool for creating a thread is used; a1) the tool can be rotated about a tool axis (A) running through the tool and can be moved axially relative to the tool axis; a2) the tool has at least one thread-creating region (4) which runs, with a predefined thread pitch (P) and a predefined thread direction (W) of the thread (50) to be created, around a tool axis (A) running through the tool, and which has an active profile corresponding to the thread profile of the thread to be created; a3) each thread-creating region has one or more thread teeth; b) the tool is moved into the preformed tap hole in the workpiece in a working motion during a first working phase; b1) the working motion involves a rotational movement with a predefined rotational direction about the tool axis (A) of the tool and an axial feed motion of the tool, which is synchronised with the rotational movement according to the thread pitch of the thread-creating region, in an axial forward direction (VB) relative to the tool axis, in such a way that the axial feeding of the tool by the predefined thread pitch equates to a full rotation of the tool about the tool axis; b2) in the working motion during the first working phase, the thread-creating region creates a thread path (50) in the wall of the tap hole (36) running below the predefined thread pitch; c) in a deceleration movement (AB) during a second working phase following the first working phase, the tool is moved further into the workpiece up to a reversal point (UP); c1) the axial feeding of the tool in relation to a full rotation at least during part of the deceleration movement, preferably during the entire deceleration movement, is less than the thread pitch and is zero at the reversal point; and c2) during the deceleration movement, the thread-creating region, in particular the thread tooth or the thread teeth, of the tool creates at least one, in particular continuous or annular, circumferential groove (51, 52) in the wall of the tap hole (36) in the workpiece.

Description

Title: METHOD FOR GENERATING A THREAD WITH A PRESET THREAD PITCH IN A PREFABRICATED CORE HOLE IN A WORKPIECE Description The invention relates to a method for generating a thread, in particular an internal thread. A thread has a helical or helical thread turn with a constant thread pitch and can be produced as an internal thread or as an external thread. To create an internal thread, a core hole (or: a core hole) is usually first created in the workpiece, which can be a blind hole or a through hole, and then the thread is created in the inner wall of the core hole. The core hole with a thread created in it is also referred to as a threaded hole. Both cutting and non-cutting methods and threading tools are known for thread generation or thread finishing. Machining thread generation is based on the removal of material from the workpiece material in the area of the thread. Non-cutting thread generation is based on reshaping the workpiece and generating the thread turn in the workpiece by pressure. An overview of the thread generating tools and work processes currently in use is given in the Handbook of Thread Technology and Milling Technology, publisher: EMUGE-FRANKEN, publisher: Publicis Corporate Publishing, year of publication: 2004 (ISBN 3-89578-232-7), im In the following referred to as the "EMUGE manual". Taps (see EMUGE manual, chapter 8, pages 181 to 298) and thread milling cutters (see EMUGE manual, chapter 10, pages 325 to 372) and, only for external winch, die dies (see EMUGE manual, chapter 11, pages 373 to 404). A tap is a thread cutting tool whose cutting edges or thread cutting teeth are arranged along an external thread below the thread pitch of the thread to be produced. When creating the thread, the tap is moved into a cylindrical core hole in a workpiece with a feed that is axial to the tool axis and while rotating around its tool axis at a rotational speed that depends on the axial feed rate according to the thread pitch, the tool axis of the tap being coaxial with the Center axis of the core hole is aligned and its cutting edges are permanently in engagement with the workpiece on the core hole wall (continuous cut), so that a continuous thread is created on the core hole wall. Typical geometries of a tap with the usual chamfer area are described in the EMUGE manual, chapter 8, pages 250 and 251 and 284 and 285. In the cutting direction in cross section perpendicular to the helix, the thread cutting teeth have a cutting profile or active profile on the outer edge and then on the inside a rake face and on the tooth back adjoining the cutting direction, free surfaces or clearance angles, so that there is no contact and therefore no friction with the workpiece takes place. A typical distribution of the individual thread action profiles of the thread cutting teeth ground diagonally in the chamfer area with the corresponding chip distribution is shown in the EMUGE manual, chapter 9, page 322. The thread cutting process with a tap is explained together with a typical torque curve in the EMUGE manual, chapter 8, page 255. After the cutting process of the tap up to the engagement of all cutting teeth, the machine spindle is braked to a standstill. Now the return or the reversing movement is started and the tooth back of the thread cutting tooth preceding the thread cutting shears off the chip still standing in the hole on its free rear side and squeezes the chip root back between the flank and the hole wall. The non-cutting thread generating tools include the so-called thread forming tools (see EMUGE manual, chapter 9, pages 299 to 324) and, only for external threads, the thread rolling tools (see EMUGE manual, chapter 11, pages 373 to 404). Tapping tools are threading tools with an approximately spiral or helical circumferential thread profile, along which several press studs (also known as shaped teeth, shaped teeth or shaped wedges) are arranged, which are generally rounded off by means of offset polygonal shapes that protrude further outwards. Corner areas of an approximately polygonal cross section of the thread groove are formed. When creating the thread, the thread tap is moved into a cylindrical core hole in a workpiece, similar to the tap, with an advance that is axial to the tool axis and rotating around its tool axis, whereby the tool axis of the tap is aligned coaxially to the central axis of the core hole. The speed of rotation and the axial feed speed are matched to one another according to the thread pitch. The press studs of the thread former are permanently in engagement with the workpiece on the wall of the core hole and press the thread turn into the wall of the core hole through plastic deformation, so that a continuous thread is created on the wall of the core hole. Typical geometries of a thread former with the usual chamfer area are described in the EMUGE manual, chapter 9, pages 308 and 309. A typical distribution of the individual thread action profiles of the thread rolling teeth rising in the threading area is shown in the EMUGE manual, chapter 9, page 322. The thread forming process with a thread former is explained together with a typical torque curve in the EMUGE manual, chapter 9, page 310. Taps and taps work with an exclusively axial feed or working movement with a synchronized rotary movement around their own tool axis according to the thread pitch. The direction of rotation of the tap and the thread former when creating the thread corresponds to the direction of winding of the thread to be created. When the thread turn is generated or at the end of the generation of the thread turn, the tool is braked and brought to a standstill at a reversal point. Braking before the reversing or reversal point is reached is normally brought about by reducing the axial feed rate and speed to a value of 0, which is synchronized according to the constant thread pitch. Now, to retrieve the tool from the workpiece, a backward or reversing movement is initiated, in which the axial feed direction and the direction of rotation are exactly opposite to the working movement and the axial feed movement and rotational movement are again are synchronized according to the thread pitch in order not to damage the thread. In practice, taps and thread formers are used which are produced monolithically, generally by machining, in particular grinding, from a blank. In addition, it is also known to form the working areas of taps with the thread teeth or thread cutting or the working areas of taps with the shaped teeth or press studs on separate thread generating elements and to attach these thread generating elements to a support body or holder. The carrier body here has the coupling shaft for coupling to the machine drive, usually via a tool holder. The materials used for the taps or taps are generally high-speed steel such as high-speed steel (HSS steel) or cobalt-alloyed high-speed steel (HSS-E steel) or hard metal such as a hard metal alloy, in particular P-steel or K-steel or cermet, or sintered carbide, in particular tungsten carbide, optionally alloyed or mixed with metals or other metal carbides, or titanium nitride or titanium carbide or titanium carbonitride or aluminum oxide, or cutting ceramics, in particular polycrystalline boron nitride (PCB), or polycrystalline diamond (PCD) are possible. The use of harder materials, which are advantageous for machining workpieces made of harder materials, in particular hard metal, for thread forming or taps is in practice severely limited by the brittleness of these materials, especially when they are used very frequently in thread production in steels, especially tough steels. In practice, in particular, when machining workpieces made of steel, the problem arises that the remaining material overhangs, in particular the chip roots and disruptive chips, especially long curly chips, when tapping or tapping claws or form bead when tapping, now come to one when running backwards after the reversal point Can lead to breakage of the brittle material. This is why taps and thread formers made of hard metal have not been able to establish themselves on the market and the predominant material is HSS. According to EP 2 229 257 B1, hard metal taps have advantages over taps made of high-speed steel due to the greater material hardness and higher compressive strength and greater temperature stability, for example theoretically a higher rotation speed and longer service life. Carbide taps are ideal for drilling threads in gray cast iron (GG) or aluminum. However, taps made of hard metal in steels have a comparatively short service life, which is usually shorter than that of comparable HSS or HSS-E taps. The shorter service life of carbide taps is probably due to the fact that the thread cutting breaks prematurely or is partially torn off or worn away due to the higher brittleness and lower elasticity as well as the lower breaking strength and toughness of carbide compared to high-speed steel. EP 2 229 257 B1 now proposes producing a targeted and defined rounding of at least part of the cutting edges of thread cutting teeth, at least in the area of the outer cutting edges or tip cutting edges, of a tap and thus increasing the service life, even if the thread cutting edges are made of hard metal and threads are cut in steel. The curvature of the cutting edge rounding and / or the removal depth of the rounded cutting edge is, in comparison to the ideal wedge shape, dependent on at least the two parameters number of thread cutting teeth in the starting area and thread pitch and preferably also on the third parameter increase of the maximum radial Distance of the outer cutting edges or the top cutting edges of the thread cutting teeth selected over the gate area. A combination tool is known from DE 10 2016 008 478 A1 with which a threaded hole is produced in a workpiece in one work step solely by an axial work movement. With this combination tool, which is referred to as a one-shot tapping tool, the core hole drilling and the internal thread cutting are carried out in a common tool stroke. In order to reduce the load on the tool, DE 10 2016 008 478 A1 proposes that after the tapping stroke, the reversing stroke does not immediately follow, but rather a groove-forming step or groove-forming stroke takes place beforehand, in which a Internal thread adjoining circumferential groove is formed without thread pitch, in which the thread profile of the tapping tool rotates stress-free can. The tapping tool is moved beyond the target thread depth for the tapping stroke until a target drilling depth is reached, namely with a groove-form feed and a groove-form speed that are not synchronized with one another and differ from Tapping feed rate and tapping speed are. The circumferential groove is generated during the groove form stroke with the help of the main cutting edge and the thread cutting tooth (or general thread tooth) of the thread profile on the tapping tool. When the target drilling depth is reached, the groove form feed is reduced to 0. At the same time, the groove-form speed is reduced to 0 in order to enable the reversal of the direction of rotation required for the reversing stroke. DE 10 2016 008 478 A1 does not provide any information on the materials for the tool. The invention is based on the object of specifying a new method in each case for producing a thread, in particular an internal thread in a core hole or an external thread, in a workpiece. In particular, the method is intended to improve the service life of taps or thread formers, which are made of a brittle material such as hard metal or cutting ceramic, at least in the area of their thread teeth, even when machining different steels. Embodiments and objects according to the invention which are suitable for solving this object are specified in particular in the patent claims, which are directed to a method for producing a thread, in particular an internal thread. Further refinements and developments according to the invention emerge from the respective dependent claims. The claimable combinations of features and objects according to the invention are not limited to the selected version and the selected back-references of the patent claims. Rather, each feature of a claim category, for example a method, can also be claimed in another claim category, for example a tool. Furthermore, each feature in the patent claims, also regardless of their back-references, can be used in any combination with one or more other feature (s) in the Claims are claimed. In addition, each feature described or disclosed in the description or drawing may, on its own, regardless of or detached from the context in which it stands, alone or in any combination with one or more other features mentioned in the pa- claims or is or are described or disclosed in the description or drawing. The method according to claim 1 is provided for producing a thread with a predetermined thread pitch in a prefabricated core hole in a workpiece. In the method, a) a tool is used to generate a thread, a1) the tool being rotatable about a tool axis running through the tool and axially movable to the tool axis, a2) the tool comprising at least one thread-generating area which has a predetermined The thread pitch and a predetermined direction of the thread to be generated runs around a tool axis running through the tool and has an active profile which corresponds to the thread profile of the thread to be generated, a3) each thread generation area having one or more thread teeth, b) moves the tool in a working movement during a first working phase into the prefabricated, ie already existing, core hole in the workpiece, b1) wherein the working movement is a rotary movement with a predetermined direction of rotation around the tool axis of the tool and one according to the thread pitch of the thread generating area with the rotary movement synchronized e includes axial feed movement of the tool in an axial forward direction axially to the tool axis, such that a full rotation of the tool around the tool axis corresponds to an axial feed of the tool by the specified thread pitch, b2) wherein the thread generation area during the first Working phase in the working movement generates a thread in the wall of the core hole that runs below the specified thread pitch, c) the tool being moved further into the workpiece up to a reversal point in a braking movement during a second working phase following the first working phase , c1) where the axial advance of the tool based on a full revolution at least during part of the braking movement, preferably during the entire braking movement, is smaller in terms of amount than the thread pitch and is zero at the reversal point and c2) where the thread generation area, in particular the thread tooth or the thread teeth of the tool produce at least one, in particular closed or ring-shaped, circumferential groove in the wall of the core hole in the workpiece during the braking movement. In order to increase the service life of taps, the invention takes a different approach than the previously mentioned EP 2 229 257 B1. While EP 2 229 257 B1 proposes an improvement to the tool, namely the rounding of the cutting edge, which can of course also be provided in the tool of the invention, the invention is based on the consideration of the process, i.e. the sequence of movements of the tool and the programming the machine control. According to the invention, it is proposed that the groove forming step provided for the special case of the combined drilling and tapping tool, which works in solid material and simultaneously generates core hole and thread, according to the aforementioned DE 10 2016 008 478 A1, between the thread generation step and The reversal point can now be used in the conventional production of threads in already prefabricated core holes with a tap that does not have or does not have to have a drilling part or drilling area, and to improve it further for this purpose. Furthermore, this advantageous combination according to the invention is extended not only for taps but also for taps or for combined tapping and thread forming tools, i.e. generally axially working thread tools with thread generating areas formed helically according to the thread pitch when generating threads in a prefabricated core hole . In a multi-part embodiment, the tool comprises a carrier body through which the tool axis runs and at least one thread generating element, in particular produced separately from the carrier body, which is fastened to the carrier body, in particular is fastened in a replaceable or detachable manner, with each thread generating element having at least one thread generating area having. In one embodiment, the or each thread generating area is arranged on a front end area of the tool and / or the or each thread generating element is attached to a front end area of the support body, preferably on an end face of the support body. In one embodiment, the thread generating element is designed as an end-face thread head with the complete thread generating area or all thread teeth, the tool axis running centrally through the carrier body and the thread generating element and the thread generating element preferably by means of a central opening in the thread generating element. In a further embodiment, several thread generating elements are fastened separately to the carrier body and are distributed around the tool axis in the circumferential direction and are arranged at a distance from one another. In an embodiment with reusable thread generating elements, the or each thread generating element has a working active thread tooth or a working active thread cutting edge and additionally at least one, in particular one, two or three, further inactive thread teeth or thread cutting edges, which, by loosening the detachable fastening, turning and / or rotating the thread generating element and re-fastening it to the carrier body, becomes one or an active working thread tooth or thread cutter. For example, the or each thread generating element in an approximately rectangular or triangular, symmetrical and plate-shaped basic shape can have four or three thread cutting edges at the four or three corners with respective upstream rake faces. In a preferred embodiment, the or each thread generating element is inserted in an associated receptacle of the carrier body, in particular on its end face, and is in particular releasable by means of a fastening screw guided through a central opening in the thread generating element exchangeably attached to the carrier body. The receptacles are preferably adapted to the thickness of the thread generating elements, so that the front surfaces of the thread generating elements are essentially flush with the front surface of the carrier body. The carrier body can now be manufactured very efficiently and, at least in the area of the thread generating element, have a cylindrical shape with respect to the tool axis, in particular also a cylindrical neck and / or at least partially made of steel, in particular high-strength steel. In another embodiment, the tool has thread generating regions formed monolithically on a base body through which the tool axis extends. In one embodiment, several, in particular five, consecutive thread teeth are separated from one another by several, for example five, preferably axially to the tool axis, separating grooves in the base body, which in particular has a cylindrical basic shape, which are arranged along the circumference around the tool axis and thread cutting in the direction of the winding and, behind it, having free surfaces, with a cylindrical outer surface of the base body being formed in particular axially behind the thread generating region formed from the thread teeth. Thread depth is lost due to the creation of circumferential grooves. It is therefore advantageous in the tool and process according to the invention if the or each thread generating area in the axial direction to the tool axis has an axial extension from a range between 0.5 P and 1.5 P of the thread pitch P or in which the threading area Tool axis axial distance between the first thread tooth and last thread tooth of the thread generation area opposite to the direction of the thread is selected from a range between 0.5 P and 1.5 P of the thread pitch P, i.e. as short as possible, which is a difference to a conventional tap or Thread forming is. To compensate for the reduced guidance of the tool as a result, in a preferred embodiment a cylindrical guide area is formed in front of the thread generation area for guiding the tool on the core hole wall in the core hole. In one embodiment, a start-up area is provided or the thread profile of the thread turn is successively cut and / or formed from the individual thread teeth to the complete thread profile and / or the thread action profiles of the individual thread teeth are divided and, when combined, result in the complete thread profile. In a particularly advantageous embodiment of the invention, the material for the thread teeth and / or the or each thread generation area and / or the thread generation elements and / or the support body and / or the base body and / or the entire tool, hard metal such as a hard metal alloy tion, in particular P steel or K steel or cermet, or cemented carbide, in particular tungsten carbide, optionally alloyed or mixed with metals or other metal carbides, or titanium nitride or titanium carbide or titanium carbonitride or aluminum oxide, or cutting ceramics, especially polycrystalline boron nitride (PCB ), or polycrystalline diamond (PCD) is used. In one embodiment according to the invention it is now provided that d) during the working movement, the (actual) speed of the rotary movement of the tool in its temporal course a first plateau at which the speed is constant at a predetermined (or: programmed or entered in the control program) maximum speed remains, runs through and e) during the braking movement the (actual speed) of the rotary movement of the tool in its temporal course runs through a second plateau at which the speed remains constant at the same predetermined maximum speed, f) where the predetermined maximum The rotational speed of the rotary movement of the tool is selected to be at least large enough that a path speed at the thread generation area of at least 57 m / min, in particular at least 85 m / min, is achieved, which is a maximum speed of at least 3000 rpm, in particular at least 4500 rpm. In one embodiment according to the invention, which is preferably combined with the aforementioned embodiments, it is provided that d) the tool is driven by a machine drive in the working movement and in the braking movement and a translation unit for the rotary movement, in particular a transmission gear unit, is switched (or: coupled) with a predefined or predefinable transmission ratio, e) the transmission ratio corresponding to the quotient of the speed of the machine drive and the speed of the tool and a maximum of 1: 3 so that the tool rotates at least three times as fast as the machine drive, f) whereby a maximum speed of the rotary movement of the machine drive is programmed in the programming of the machine drive, which corresponds to the product from the transmission ratio and the specified maximum speed of the rotary movement on the tool corresp ot. In one embodiment, there is an intermediate time interval between the time interval of the first plateau of the speed and the time interval of the second plateau of the speed, in which the speed drops below the maximum speed. In one embodiment, the ratio of the interval length of the intermediate time interval to the interval length of the time interval of the second plateau is in a range from 0.5 to 2.4. In one embodiment, the interval length of the second plateau is selected in a range from 0.01 s to 0.25 s, in particular 0.02 s to 0.13 s, and / or the interval length of the intermediate time interval is between 0 in one embodiment .05 s and 0.15 s, in particular between 0.06 and 0.10 s. In one embodiment, the maximum speed is already reached at the beginning of the first work phase or the work movement or at the point where the tool enters the workpiece. In one embodiment, the maximum web speed achieved in the thread generation area is selected in a range from 57 m / min to 189 m / min, in particular from 85 m / min to 132 m / min. In one embodiment, the transmission ratio is generally selected between 1: 3 and 1:10, in particular between 1: 4 and 1: 8, preferably between 1: 4 and 1: 5. The braking movement preferably comprises a rotary movement with a constant direction of rotation as in the working movement. As a rule, the braking process or the second work phase begins with an axial feed that corresponds to the thread pitch of the first work phase. The braking process is to be understood as braking from the initial thread pitch to zero at the end or at a reversal point and does not have to include a reduction in the axial feed rate over the entire angle of rotation interval depending on the angle of rotation (braking acceleration), in particular to values below the thread pitch. Rather, rotation angle intervals are also possible in which the axial feed is zero or even temporarily negative in relation to the rotation angle, that is to say reverses its direction. In a preferred embodiment, the axial feed movement is controlled during the braking movement as a function of the rotational angle of the rotational movement of the tool according to a previously stored unambiguous relationship, in particular a function or a sequence of functions, between the axial advance of the tool and the rotational angle . A function that defines the relationship between the axial feed (or: the axial penetration depth) and the angle of rotation can have a continuous definition range and value range or a discrete definition range and value range with discrete, previously stored or previously determined value pairs or value tables exhibit. In one embodiment, the rotational speed of the rotational movement at the reversal point is also zero. and / or the total or total axial feed of the tool during the braking movement is selected or set between 0.1 times to 2 times the thread pitch. In a preferred embodiment, different relationships, in particular functions, between the axial advance of the tool and the angle of rotation are selected or set during the braking movement in several successive braking steps. In a particularly advantageous embodiment, a linear function of the angle of rotation is selected during several, in particular all, braking steps for the axial penetration depth or the axial advance and / or the (programmed) slope, ie the derivation of the axial penetration depth or the axial advance according to the angle of rotation, is constant in each of these braking steps and decreases in amount from one braking step to a subsequent braking step. This embodiment can be implemented in a particularly simple manner by using an NC control for a thread process, for example a G33 path condition, with the thread pitch of the thread for the work movement and also one, preferably the same, NC control for a thread process in the several braking steps , for example a G33 path condition, with the respective constant pitch is used as the thread pitch parameter. In one embodiment, during several, in particular all, braking steps, the axial penetration depth or the axial advance is an, in particular cubic, spline function of the angle of rotation. In one embodiment, the different functions of the successive braking steps are continuously and, in the case of differentiable functions, preferably continuously differentiable. In one embodiment, in particular during an equalization step, the axial advance during the braking movement is zero in a rotation angle sub-interval and / or takes place in a rotation angle sub-interval in the reverse direction opposite to the forward direction of the working movement. In one embodiment, after the reversal point has been reached, a reversing movement of the tool is initiated, with which the tool is moved out of the workpiece, the reversing movement initially being a first reversing phase with which the thread generating area of the tool is guided back into the thread of the generated thread, and subsequently a second reversing phase, during which the thread generation area is guided out of the workpiece through the thread turn. The reversing movement is preferably carried out with a course of movement that is symmetrical to the working movement and the braking movement, with a reversed direction of rotation and reversed feed. In an advantageous embodiment, the reversing movement in the first reversing phase with the same absolute value, inverted only in the direction of rotation and feed direction, is stored in advance, in particular a function or a sequence of functions, between the axial feed of the tool and the angle of rotation controlled as in the braking movement during the second work phase, possibly omitting or shortening the leveling step, if available. The invention is explained further below with the aid of exemplary embodiments. Reference is also made to the drawing, in which FIG. 1 shows a thread generating tool during the generation of a thread, FIGS. 2 to 10 successive steps of a method or cycle for generating a thread with a thread generating tool, in particular according to FIG. 11 shows a thread produced with the method and tool according to FIGS. 1 to 10, FIG. 12 shows the control of a thread generation cycle using a graph of the axial penetration depth as a function of the angle of rotation, FIG. 13 shows the end section of the graph shown in FIG. movement as a braking process, FIG. 14 the end section of the graph shown in FIG. 12 in the backward movement as an acceleration process, FIG. 15 a diagram of the penetration depth and the speed as functions of time with a transmission unit between the drive unit and the tool according to the invention, and FIG. 16 a diagram of the penetration depth and the speed as a function of time without a translation unit between the drive unit and the tool, FIG. 17 a thread generating tool with three thread teeth on an end thread generating element on a carrier body in a perspective illustration, FIG. 18 a thread generating tool with six end threads 19 shows the thread generation tool according to FIG. 18 in a perspective illustration, FIG. 20 shows the thread generation tool according to FIGS. 18 and 19 in a side view, FIG. 21 shows the thread generation tool according to FIGS compared to FIG 20 rotated side view, 22 shows a thread generating tool with eight thread teeth on an end-face thread generating element on a carrier body in a perspective view, FIGS. 23 to 26 a monolithic thread generating tool according to the invention, and FIGS. 27 to 30 exemplary embodiments for the division of the thread knitting profiles of the thread teeth, each in a cross section, are each shown schematically. Corresponding parts and sizes are provided with the same reference numerals in FIGS. 1 to 30. First exemplary embodiments of the tool and method according to the invention are explained below with reference to FIGS. 1 to 11. The tool 2 shown in FIG. 1 is used to produce a thread 5 in a workpiece 6. For this purpose, the tool is moved into the core hole 35 in the workpiece 6 in a working movement or a working stroke or a thread generating movement, which is composed of a rotary movement around the tool axis on the one hand and an axial feed movement along the tool axis. The diameter of the core hole 35 is denoted by d. 11 shows an embodiment of a threaded hole 36 with a thread 50 and a thread profile 55 of the thread 5, which can be produced with a method or a tool according to the invention, for example according to FIG. 1 or 2 to 10. The thread pitch angle δ of the thread turn 50 with the thread pitch P and the diameter D is measured with respect to a transverse plane E, which is directed perpendicular to the tool axis A, and is based on the following relationship P = π · D tan · δ predictable. Typical values for the thread pitch angle d are, for example, between 1 ° and 5 °. The tool 2 is on the one hand rotatable or rotationally movable about a tool axis A running through the tool 2 and on the other hand it can be moved axially or translationally along or axially to the tool axis A. These two movements are coordinated or synchronized with one another, preferably by a control unit, in particular a machine controller, while the tool 2 penetrates a surface 60 of the workpiece 6 and into the core hole 35 of the workpiece 6 to a hole depth LT. The tool axis A remains stationary or in a constant position relative to the workpiece 6 while the thread 5 is being generated. During the process, the thread center axis M of the thread 5 is coaxial with the tool axis A or coincides with it. The tool 2 is preferably by means of a coupling area on a tool shaft 21 running or formed axially to the tool axis A by means of a rotary drive (not shown), in particular a machine tool and / or drive or machine tool spindle, rotationally or in a rotary movement around its tool axis A as the axis of rotation in a forward direction of rotation VD and can be driven in an opposite reverse direction of rotation RD. Furthermore, the tool 2 is axially movable in an axial forward movement VB or an axial backward movement RB axially to the tool axis A, in particular by means of an axial drive, which in turn can be provided in the machine tool and / or drive or machine tool spindle . At a free end area of the tool 2 facing away from the coupling area of the tool shank 21, a carrier body 20 is provided, on which a thread generating area 4 is monolithically or integrally formed or via one or more separate thread generating elements (not shown in FIG. 1) - is ordered or secured. The thread generation region 4 is that along a helix (or: helix, thread turn), the pitch of which corresponds to the thread pitch P and the direction of the thread of the inner thread or thread 50 to be generated. speaks, runs or is trained. In this sense, the helical line is to be understood technically and not as a purely mathematical one-dimensional line, but also has a certain extent transversely to the mathematical line, which corresponds to the corresponding dimensions of the thread-generating area 4. Mathematically, one would otherwise have to speak of a family of helical lines running parallel to each other or possibly of a screw band or a helix band. The direction of winding of the thread generating area 4 as a right-hand thread or left-hand thread corresponds to the superposition of the axial forward movement VB and the forward rotational movement VD. The thread generation region 4 comprises one or more, i.e. a number n greater than or equal to 1, thread teeth which are designed to be cutting and / or shaping. Preferably n = 2. Each thread tooth is designed or aligned or arranged to run along the helical line. Each thread tooth has a thread tooth profile as an active profile, which generally results or represents the outermost dimension or outer profile of the thread tooth in a projection along the helical line and is mapped into the workpiece during the thread generating movement, be it by cutting or by shaping or pressing . If several (n> 1) thread teeth are included in the thread generation region 4, then these thread teeth are arranged offset to one another at least approximately along the helical line (or in the axial direction). Such an arrangement along the helical line also includes embodiments in which the thread teeth are slightly offset to the side of an ideal line, for example to create thread action profiles with different processing on the thread flanks or a different division or superposition of the thread action profiles on the or to realize the overall thread profile. With regard to this arrangement of the thread teeth, it is only important that their arrangement is mapped onto a thread turn in the workpiece with the same thread pitch P during the working movement. In the exemplary embodiments shown in FIGS. 1 to 10, two threaded teeth 41 and 42 are provided which, for example, by half or generally 1 / n of the thread pitch P are axially offset from one another, that is to say they are offset by half a turn or by 180 ° in the angular direction. The outer diameter of the thread generation area 4 and of the thread turn 50 and thus of the thread 5 is denoted by D. The thread profile of the internal thread, i.e. the cross-section through the thread turn 50, is generated by the thread effect profile, which is composed or superimposed from the individual active profiles of the thread teeth, e.g. 41 and 42, when completely through the workpiece. The thread profile width of the thread active profile measured in axial projection onto the tool axis A is denoted by c and corresponds to the maximum distance between the thread profile flanks. The axial distance measured in the axial projection onto the tool axis A between two successive thread profiles of the thread turn 50 is the thread gap b. The sum of the thread gap b and the thread width c corresponds to the thread pitch P. In these exemplary embodiments, the thread teeth 41 and 42 are in the carrier body 20 and / or by separating grooves 25, which in particular form chip grooves or also coolant and / or lubricant grooves. or the thread generating element (s) separated from one another. The separating grooves 25 continue through the thread generation area 4, in particular into the shaft area, and run preferably twisted at a constant or variable twist angle, which is typically in an interval of 0 ° to 50 °, in particular 20 ° to 35 ° . In an advantageous embodiment, the following method is carried out with the tool 2 or another tool according to the invention: During a first work phase or thread generation phase, the thread 50 is generated with the tool 2 in the core hole wall of the core hole 35 by means of the thread generation area 4. In this first work phase, the axial feed rate v along the tool axis A is matched and synchronized with the rotational speed for the rotational movement around the tool axis A so that the axial feed rate corresponds to the thread pitch P for one full revolution. The axial penetration depth (or: the axial feed) T in the direction The direction of the tool axis A measured from the workpiece surface 60 in this first work phase corresponds to the thread depth TG. The variable T corresponds to the z-axis in a normal NC machine control. Now, in a second work phase immediately following the first work phase, in a braking process (or: in a braking movement), the tool 2 is braked in an angle of rotation interval in such a way that the axial advance V is at an angle of rotation of 360 °, ie at a full revolution, of the tool 2 is smaller than the thread pitch P and decreases to zero. As a rule, the braking process or the second work phase begins at an axial feed based on an angle of rotation of 360 °, which corresponds to the thread pitch P of the first work phase, i.e. V = P, and then reduces the axial feed per 360 ° angle of rotation to values below the thread pitch P, i.e. V <P. The braking process is to be understood as braking from the initial thread pitch V = P to zero at the end or at a reversal point, i.e. V = 0, and does not have to be reduced over the entire rotation angle interval of the axial feed V as a function of the angle of rotation (braking acceleration). Rather, rotation angle intervals are also possible in which the axial advance is zero or even temporarily negative in relation to the rotation angle, that is to say reverses its direction. In a preferred embodiment, this braking process takes place in defined sub-steps, as will be explained in more detail below. This braking movement in the second work phase leads to the thread generating area 4 now generating at least one circumferential groove or circumferential groove or circumferential groove (or: an undercut) in the core hole wall of the core hole 35 in an actually atypical or non-functional manner. The process in the second work phase can therefore not only be referred to as a braking process but also as a circumferential groove creation or circumferential groove creation or undercut movement, and in the case of a purely cutting tool, it can also be referred to as a free-cutting movement. In FIG. 1, the thread generating teeth 41 and 42 are shown with the same outer radius D / 2 and preferably the same active thread profile, which already corresponds to the end profile of the thread turn 50. The thread generating teeth 41 and 42 of the tool according to FIG. 1 generate in the second work phase a circumferential groove 51 with the continuous outer diameter D and the axial length a, which results from the total axial advance of the braking movement in the second work phase up to the reversal point. In contrast, FIG. 11 shows two circumferential grooves 51 and 52, the first circumferential groove 51 having an outside diameter d lying between the core hole diameter d and the thread outside diameter D and the second circumferential groove 52 having an outside diameter which corresponds to the thread outside diameter D. Such circumferential grooves 51 and 52 can be produced during the second working phase, for example, with two thread generating teeth 41 and 42 offset by P / 2, as shown for example in FIG. 1, which can be modified as follows: The first thread generating tooth 41 in FIG 1 have only one outer radius d '/ 2 and thus be a chamfer or lead tooth which does not generate the thread pitch 50 to the full profile depth or to the final thread root, while the second thread generation tooth 42 already has the full profile - has ß diameter D, i.e. the full thread profile depth is generated (full tooth). In this exemplary embodiment, the circumferential groove is thus composed of two partial grooves, namely the first circumferential groove 51 with a smaller diameter, which is produced by the first thread generating tooth 41, and the second circumferential groove 52 with the full diameter D, which is produced by the second thread generating tooth 42 is generated. These explanations are only exemplary. If there is a different number or distribution of thread generating teeth, which is not shown, correspondingly different circumferential grooves result. If you want to produce the circumferential groove (s), for example the circumferential grooves 51 and 52 in FIG. 11 or the circumferential groove 51 in FIG. 1, continuously or uninterrupted in the axial direction, the axial feed rate V is at full rotation or 360 °, in particular reduced by at least b / n compared to P, in order to close the thread gap b or no longer generate it, where n is the number of thread generating teeth in the thread generating area 4. The undercut movement or braking movement can also be carried out, for example by suitable selection of the movement parameters or by additional axial equalizing movements, so that the outer width on the thread profile, in particular the flanks, are no longer visible in the circumferential groove or disappear and / or the circumferential groove only has a cylindrical shape. In this way, the screwability of the workpiece thread produced could be improved or made possible. In the exemplary embodiments shown in FIGS. 1 to 11, n = 2 with the two thread generating teeth 41 and 42 or circumferential grooves 51 and 52, so that the axial advance V during the braking process is preferably set to be less than P − b / 2. The thread action profile of the thread generating teeth, here 41 and 42, then no longer generates a thread in the superposition during the movement, but at least one continuous circumferential groove that has the same outside diameter as that of the associated thread generating tooth on its respective path during the braking movement in the second work phase. The total depth or hole depth or total axial dimension of the threaded hole 5 after the second work phase is denoted by TL and essentially corresponds to the sum of the thread depth TG as the axial feed in the first work phase and the axial groove length a as the axial feed in the second working phase as well as the axial depth of the remaining hole sub-area 56. If the total depth or hole depth T_L. of the threaded hole 5 is reached, the tool 2 comes to a standstill and reaches a reversal point UP. A reversing or backward movement RB is then initiated immediately at the reversal point UP, with which the tool 2 is initially moved back in a first reversing phase through the circumferential groove (s) 51, 52 as far as the thread turn 50 and then in a second reversing phase through the thread 5 or the thread turn 50 outwardly out of the threaded hole 36 and then the workpiece 6 or is threaded out. More will be explained later on a preferred embodiment of the first reversing phase. In the second reversing phase of the backward movement RB, the axial feed and the rotary movement of the tool 2 are again synchronized with each other according to the thread pitch P in order not to damage the thread, except that the direction of the axial feed is in the direction of the arrow of the backward movement RB compared to the The direction of the arrow of the forward or working movement VB is interchanged or opposite and the direction of rotation of the rotary movement is also reversed, that is, the reverse direction of rotation VR is now set instead of the forward direction of rotation VD. The thread axis or central axis of the thread with the thread turn 50 is denoted by M and falls during the entire working movement, i.e. both in the first working phase and in the second working phase, and also during the reversing movement, i.e. both in the first reversing phase and in the second reversing phase, together with the tool axis A of the tool 2 or is coaxial with it. FIG. 12 uses a diagram to show an exemplary embodiment of a process (or: method) or a control sequence that can be used to generate a thread in the workpiece. In the graph of the function T (f) according to FIG. 12, without restricting the generality, in particular the generation of a threaded hole, ie a complete thread generation cycle according to the invention, is illustrated in one embodiment, in particular a thread generation cycle with a first work phase, a second work phase , Reversal point, first reversing phase and second reversing phase, for example as already described with reference to FIGS. In the diagram of FIG. 12, the penetration depth (or: vertical or axial coordinate) T is on the vertical axis or ordinate as running and measured in the axial direction, ie along the tool axis A and the central thread axis M coaxial with the tool axis A Coordinate for the axial feed plotted in mm. The values for the penetration depth T decrease from the value shown at the top, which corresponds in particular to the axial entry position on the workpiece surface 60 of the workpiece 6 (which is also shown in FIG. 2) down to a lowest value The numerical range in the example in FIG. 1 extends from T = 0 mm as the uppermost value to, for example, T = - 17 mm as the lowest value, but depending on the desired thread length and tool design, Of course, other values are also possible. The (summed up) angle of rotation f of the rotary movement of tool 2 around its tool axis A is plotted in degrees [°] on the horizontal axis or abscissa. The angle of rotation f is based on the entry angle of rotation or the initial angle of rotation f = 0 ° at the axial entry position T = 0 mm at an entry point EP = (0, 0) and increases to the right towards positive values up to the value of f = 8000 ° entered as the last value on the abscissa. The angle of rotation f increases towards positive values during the forward rotation movement VD or in a forward direction of rotation and decreases during the backward rotation movement RD or in a reverse direction of rotation opposite to the forward direction of rotation. In this case, ± 360 ° corresponds to a complete revolution of the tool 2 around its tool axis A. The function T (f) describes the dependency or synchronization of the axial feed movement in the axial coordinate (or: depth in workpiece 6) T of o- that with the rotary movement in coordinate f and is typically stored in a control such as a numerical control or CC control of the machine tool, in particular in the form of a previously determined and stored value table or as a function for the respective calculation. According to the nomenclature customary in CNC technology, the T coordinate would correspond to the Z axis (spindle axis), the positive direction running conventionally from the workpiece to the tool, as shown in FIG. 1 at coordinate T, for example. According to FIG. 12, the graph (f; T (f)) of the function T (f) initially runs a linear section that is typical of a tap or thread former and corresponds to the generation of the thread, ie in the form of a straight line, from the starting point f = 0 ° and T = 0 mm up to a thread end point at f0 and T (f₀), at which the thread turn or the actual thread generation ends and which in the example shown is - 16 mm without restricting the generality. The representation of the linear function T (f) in this section from f = 0 to f = f0 and T = T (0), in particular 0 mm, to T = T (f0), in particular - 16 mm applies:

with the thread pitch P. The pitch or derivative dT / df in this area is constant and corresponds to the amount according to P / 360 °. So that means for the thread pitch

Since in the example chosen in FIG. 12 the value for the thread depth corresponding to the entered angular value f = 3600 ° is T = -10 mm, the slope of the straight line is -1 mm / 360 ° and thus the thread pitch P = 1 mm. Due to the axial feed, which is synchronized with the rotation, along the penetration depth T or thread center axis M, all components of the tool 2 have moved on by the thread pitch P in a complete rotation through 360 °. The linear section of the function T (f) corresponds to the usual synchronized tap or thread forming kinematics and can be stored in a CNC control, for example, as a pre-programmed path condition (address letter G or G function), e.g. as G33, in particular G331 and G332, where the thread pitch P is entered as an interpolation parameter parallel to the Z-axis, typically under the address letter K in the CNC nomenclature. The thread generation process takes place in this linear section, in particular to generate the thread 50 in the first work phase, of which various positions or sections with increasing penetration depth T are shown in particular in FIGS. 3 to 6, and the result is a thread of thread depth T_G as the interval length of the penetration depth T, in particular from T = 0 to T₀, over the interval length or the rotation angle range f_G of the angle of rotation f, in particular from f = 0 ° to f = f0. In the example in FIG. 12, the thread generation process (first work phase) takes place from f = 0 ° to f = f0 and from the corresponding penetration depth T = 0 mm to T = -16 mm. The gradient of the straight line in FIG. 12 between f = 0 and f = f0 corresponds to the axial feed rate of the tool 2, which is synchronized to the angle of rotation f according to the thread pitch P. The time dependency of the angle of rotation f (t) as a function of time t and thus penetration depth T (t) as a function of time t can in principle be varied during the thread generation process - even over a wide range. Preferably, however, the rotational speed df / dt and the axial feed speed dT / dt are each constant during the working movement VB. If the rotational speed df / dt is changed, the axial feed speed dT / dt, ie the derivative of the penetration depth T after the time t, must also be adjusted accordingly, so that the synchronization of the axial feed Z according to the relationship Z = P / 360 ° is maintained. This is the well-known kinematics implemented in machine tool controls or NC controls for thread generation by means of an axially working thread tool such as a tap or thread former. Following the thread generation process (first work phase), in particular in the second work phase, a braking process or a braking movement AB takes place in a rotation angle range Df between the rotation angle values f0 and f_n and an associated penetration depth range DT, which in the example of FIG from T (f0) = - 16 mm to T (f_n) = - 17 mm is sufficient. At the end of the braking movement AB, a reversal point UP is reached, at which the tool 2 comes to a standstill briefly both in terms of the rotary movement and in terms of the axial feed movement. At the reversal point UP, the maximum angle of rotation range is fL, where fL = fG + Df, and the maximum penetration depth T_L. for the threaded hole 36 is reached. During the braking process or the braking movement AB, the axial feed rate is reduced as a function of the angle of rotation, which corresponds to the slope of the graph shown for the function T (f), according to a dependency or function that is preferably strictly monotonous (slope always falls - lend) or monotonous (gradient falling and possibly also zero in sections), but can also temporarily rise slightly again in partial sections. The gradient is preferably set in a predetermined number n of individually defined, programmed or stored partial steps or braking steps S_i successively reduced, the total number or number n being a natural number with n> 1, generally 200> n> 2, in particular 20> n> 5 being selected, and where i is the counting index for the braking step S_i is and lies between 1 and n, so 1 £ i £ n holds. In each sub-step or braking step S i, a synchronization of the axial feed T (or the feed speed dT / dt) and the rotation angle f (or the rotation speed df / dt) corresponding to the control of a threading process is preferably set or programmed by adding S_i with 1 £ i £ n an associated predetermined function T_i(f) with an associated value interval [T_{i -1}, T_i] over the associated angle of rotation interval [f_{i -1}, f_i] is assigned or programmed. The function T_i(f) is preferably linear, so the graph is (idealized) a straight line. The programmed or stored slope increases from each deceleration step S_i to the next braking step S_{i + 1} gradually or successively, i.e.. The slope corresponds to a slope parameter

meter. In an advantageous embodiment, this pitch parameter is programmed as a thread pitch in the CNC control, ie in particular as an interpolation parameter along the z-axis or the thread axis M in a G33, in particular G331 and G332, path condition. This means that the path conditions or G functions already specified in the control programming can be used and only the input parameter for the thread pitch has to be successively changed or reprogrammed. Thus, in each deceleration step S_i the associated slope parameter

programmed or set, where P_{i + 1} <P_i for all i with 1 £ i £ n. Furthermore, P_i <P i.e. the pitch in the second work phase or during the braking movement AB is smaller than the thread pitch P during the first work phase. In particular, but without loss of generality, P_i = P (n - i) / n. In general, the last value is P_n still greater than 0, even if it is the smallest of the values P_i is. The values of P_i can, for example, be selected in such a way that a continuous movement into the free cutting area is possible from the thread pitch movement. In particular, the speed of the tool should be maintained as far as possible. From this, for example, various conditions can be formulated that can be mapped in approximation functions. In this case, S applies in each braking step_i for all i with 1 £ i £ n the relation: T (f) = T_{i -1} - (P_i / 360 °) (f ˗ f_{i -1}) for f ^ ^ ^ [f_{i -1}, f_i] with the boundary conditions T (f_{i -1}) = T_{i -1} and T (f_i) = T i. The angle of rotation range ^ f for the braking movement AB in the second work phase is generally selected to be smaller than the angle of rotation range f_G for thread generation in the first work phase, in particular ^ f <0.5 fG and preferably ^ f <0.2 fG is selected. This can depend in particular on how large the usable thread length is. Another influencing factor is the intended function in the undercut. If, in addition to the pure braking, one would like to make additional rotations to cut the chips free, additional rotations can be added (see further below for FIGS. 21 and 22). The penetration depth range (or: the maximum penetration depth) ^ T for the braking movement AB In the second working phase, the selected range is generally smaller than the penetration depth range or the thread length T._G for thread creation in the first work phase, in particular ^ T <0.5 TG, preferably ^ T <0.2 TG, is selected. The penetration depth range ^ T for the braking movement AB can in particular be selected to be equal to P. A penetration depth range ^ T less than P is also possible in order to keep the thread hole depth smaller, for example 0.5 P or 0.25 P. For reasons of machining, it may also be advantageous to have larger undercut heights or a larger penetration depth range ^ T should be selected, especially up to 2 P and in exceptional cases larger. In an exemplary embodiment of a braking movement AB in an angle of rotation range ^ f ^ and an associated penetration depth range ^ T, n = 10 is selected as an example and without loss of generality, and ten braking steps S1 to S10 with the associated slope parameters P1 to P10 are provided. The rotation angle range ^ f ^ is divided accordingly into the n = 10 rotation angle intervals [f0, f1], [f1, f2],…, [f_{i -1}, f_i], [f_i, f_i+1],… [f ^, f10] and associated with these intervals are the corresponding penetration depth intervals [T0, T1], [T1, T2],…, [T i-1, T i], [T i, Ti + 1], ..., [T9, T10], into which the penetration depth range ^ T is divided, which in the example of FIG₀) = -16 mm to T (f₁₀) = - 17 mm is sufficient and / or corresponds to the thread pitch - P = - 1 mm. A sub-step S i corresponds to each interval. An associated pitch parameter P i, in particular as a thread pitch or interpolation parameter of the CNC control, is assigned to each of these intervals of each braking step S i, that is to say pitch P to the two intervals [f0, f1] and [T0, T1]₁, the pair of intervals [f₁, f₂] and [T₁, T₂] the slope P₂ and so on up to the slope P10 for the last pair of intervals [f9, f10] and [T9, T10]. The slope values P₁ to P₁₀ are chosen so that P_{i + 1} <P_i is for i = 1 to i = n, in particular n = 10. S in each subsection or braking step_i the thread pitch remains P₁ to P₁₀ constant, so that essentially straight sections of the graph of the function T (f) result in which a synchronized “thread movement” takes place, that is, the axial feed rate is the quotient of P_i/ 360 °. The penetration depth intervals in the braking steps S i are preferably selected to be the same for all i with 1 £ i £ n (here, for example, n = 10), so that the length of the intervals T1 - T0 = T2 - T1 = T i - T i -1 = T i + 1 - T i = Tn - Tn-1 is chosen to be equal or equidistant, i.e. T i - T i-1 = ^ T / n. Since the axial feed is chosen to be constant in each sub-section or sub-interval in this exemplary embodiment, since T i + 1 - T i is chosen to be the same or equidistant for all i, the result is a decreasing slope P i and thus a decreasing axial feed rate increasing rotation angle intervals f i + 1 - fif i + 1 - fi> fi - fi -1 in the angle of rotation range ^ f in the braking steps S i. I.e. the angle of rotation distance f₂ - f₁ is smaller than the angle of rotation distance f₃ - f₂ and the angle of rotation distance f_{i + 1} - f_i is greater than the angular distance f_i - f_{i -1}. The last section between the rotation angle values f10 - f9 covers the largest angular distance or angular range. This corresponds to a continuous braking process that is slowed down in each subsection or braking step S i. During the braking movement AB, the time dependency of the rotational speed d f / dt and the axial feed rate dT / dt is selected or controlled or programmed in such a way that the tool 2 at the reversal point UP = (f_n, Tn) or (f10, T10) comes to rest, i.e. d f / dt = 0 and dT / dt = 0 at f = f_n or T = T_n or if f = f₁₀ or T = T₁₀. The tool 2 at the reversal point UP is also shown in FIG. The reduction of the rotational speed d f / dt and the axial feed speed dT / dt to 0 depending on the time t can, for example, take place continuously during the braking movement AB or, for example, only in the last braking step S_n or S₁₀. From the inertia of the drive system, in particular the control and the machine drives and the inertia of the moving components, the graphs in the braking steps S1 to S10 or during the braking movement AB are not exactly linear but rather rounded. Represented in an idealized manner or stored in the programming of the braking movement itself, however, the described sequence of linear functions or strung together linear sections with gradually decreasing gradient, i.e. gradually decreasing constant feed speed, results in the individual braking steps S._i for example S.₁ to S.₁₀. Before initiating an extension or reversing movement, an intermediate step can be carried out, such as a cleaning process. Here, for example, remains of the chip root can be removed by further turning the tool or the circumferential groove can be cleaned of remnants of the thread tips in order to obtain a cleaner cylindrical area. Then it would be easier to screw in a screw. After the reversal point UP has been reached, in one embodiment, as shown in particular in FIG. 12, a reversing movement or backward movement RB is initiated, which initially comprises an acceleration movement BB in a first reversing phase up to the threading into the thread 50, which for example in FIG. 8, and in a second reversing phase a backward movement RB, in which the tool 2 is threaded out through the thread 50 in a synchronized manner, which is shown in FIG. 9, for example. In an advantageous embodiment, the control curve or function according to FIG. 12 can now be used or run through in the reverse order and / or symmetrically to the reversal point UP. The rotational movement is reversed for the backward movement RB or BB from the forward direction of rotation VD to the reverse direction of rotation RD, i.e. the angle of rotation f starting from f = f_n or f = f₁₀ preferably reduced at the reversal point UP or turned back in the negative direction until finally the initial value f = 0 is reached again and the tool 2 emerges from the workpiece 6. The dependency or function T (f), which is preferably taken over unchanged, now results in the penetration depth T becoming smaller in terms of amount as the angle of rotation decreases, that is to say from T = T_n or T = T₁₀ at the reversal point UP again decreases to T = 0 at the entry point EP at f = 0, which is thus also the exit point at the same time. In particular, the first reversing phase corresponds to the second work phase and the second reversing phase corresponds to the first work phase. In particular, an embodiment can also be used for the second working phase in reversed order for the first reversing phase. In the first reversing phase, starting from the reversal point UP, the same dependency or function T (f) can be used in the opposite order for the acceleration movement BB in reversing the braking movement AB. However, other functions T (f) and sub-steps can also be used, which preferably relate to point (f₀, T₀) at which the braking Movement AB began or the first work phase ended, so that the correct threading point for the tool for moving back through the thread 50 can be reached. Preferably, starting from the final angle value f_n or f10, in the reverse order, initially an acceleration phase as the first reversing phase with an acceleration movement BB carried out with the same incremental steps. However, these steps are now acceleration steps S_j with n + 1 £ j £ 2 n, starting with S₁₁ to S._20th for n = 10. S is assigned to each of these acceleration steps_j an associated angle of rotation interval [f₁₀, f₁₁], [f₁₁, f_12th],…, [F_{j -1}, f_j], [f_j, f_{i + 1}], ... [f_^^, f_20th], where f_j from the first reversing phase simply corresponds to f i from the second working phase if i + j = n. The slope parameters also remain the same, only in reverse order, so they are changed by P₁₀ about P₉, P_8th up to P₁ run through for the partial sections of the control curve according to FIG. 12 from right to left until the depth value T₀ is achieved. A new angle value f₁₁ Assumed temporally after the angle value f10 and the interval [f10, f11] corresponds to the interval [T10, T9], with the thread pitch P10 and the subsequent angle interval [f11, f_12th] the penetration depth interval [T₉, T_8th] with the corresponding thread pitch P₉ etc. up to the last section of [f_19th ^ ^ f_20th] according to [T₁, T₀] with the thread pitch P₁. Subsequently, in the reverse direction of FIG. 12, the linear section of the curve of f₀ up to f = 0 corresponding to the penetration depth T of T.₀ traverse up to T = 0. The axial feed speed corresponding to the gradient of the straight line in FIG. 12 during the backward movement is now again P / 360 ° with the opposite direction. As a result, the tool is guided in reverse through the thread generated in the forward movement, without the thread turn being damaged in the thread. The backward movement is synchronized in exactly the same way as the forward movement, only with the opposite direction of rotation, so that the angle f differs from the angle f_n straight back in its value decreases down to f = 0 and the thread depth from T = T0 to T = 0 also increases mathematically when the axial feed rate is reversed. Using the same control curve or function T (f) as in the forward movement VB in the two working phases also in the backward movement RB in the two reversing phases has the advantage, on the one hand, that the tool 2 can be controlled with exact positioning or movement is in the correct position, in particular when threading into the thread 50, and in this way the forces during reversing can be kept very low and / or a high return or extension speed is made possible. In one embodiment of an implementation of the described dependencies or functions for T (f), the values of the penetration depth T are used as input parameters measured or specified by the controller or programming, and the associated values of the angle of rotation f ^ result from the dependency using the assigned slope parameters P. and P i. An NC program for tapping or thread forming can therefore be selected, in particular with a G33, in particular G331 and G332, path condition with a thread pitch to be entered, and a sequence or set of values for the penetration depth can now be specified for which a new Thread pitch parameter is switched over, the thread pitch parameter being retained until the next value of the penetration depth. FIG. 13 now shows an exemplary embodiment of a braking movement AB in an enlarged view of the lower right area of the diagram in FIG. 12 in an angle of rotation range ^ f ^ and an associated penetration depth range ^ T. In FIG. 13, n = 10 is selected as an example and without loss of generality, and ten braking steps S1 to S10 with the associated slope parameters P1 to P10 are thus shown. The rotation angle range ^ f ^ is accordingly divided into the n = 10 rotation angle intervals [f₀, f₁], [f₁, f₂],…, [F_{i -1}, f_i], [f_i, f_{i + 1}], ... [f_^, f₁₀] and associated with these intervals are the corresponding penetration depth intervals [T₀, T₁], [T₁, T₂],…, [T_i-1, T_i], [T_i, Ti +₁],…, [T₉, T₁₀], into which the penetration depth range ^ T is divided, which in the example in FIG. 12 ranges from T (f0) = -16 mm to T (f10) = - 17 mm and / or which corresponds to the thread pitch - P = - 1 mm . A sub-step S i corresponds to each interval. In FIG. 13, unlike in FIG. 12, the differential angle of rotation is plotted on the basis of f0. If you want to enter the same values on the rotation angle axis for f as in FIG. 12 in FIG. 13, then all values on the horizontal axis must be added to the value of f0, which in FIG. 12 is 5800 °, for example. The braking movement AB begins at the angle of rotation value f0 and the associated penetration depth value T₀ and ends at the final angle of rotation value f₁₀ and the associated penetration depth value T₁₀. It is now each of these intervals of each braking step S_i an associated slope parameter P_i, in particular as a thread pitch or interpolation parameter of the CNC control, assigned to the two intervals [f₀, f₁] and [T₀, T₁] the slope P₁, the pair of intervals [f₁, f₂] and [T₁, T₂] the slope P₂ and so on up to the slope P10 for the last pair of intervals [f9, f10] and [T9, T10]. The slope values P₁ to P₁₀ are chosen so that P_{i + 1} <P_i is for i = 1 to i = 10 in FIG. 13 or n in FIG. 12. In each subsection or braking step S_i the thread pitch remains P₁ to P₁₀ constant, so that essentially straight sections of the graph of the function T (f) result in which a synchronized “thread movement” takes place, that is, the axial feed rate corresponds to the quotient of P_i/ 360 °. In the exemplary embodiment shown in FIG. 13, the penetration depth intervals in the braking steps S were_i for all i with 1 £ i £ n (here eg n = 10) chosen to be the same size, so that the length of the intervals T1 - T0 = T2 - T1 = T i - T i -1 = T i + 1 - T i = Tn - Tn-1 is chosen to be equal or equidistant, that is T i - T i-1 = ^ T / n in the exemplary embodiment shown in FIG. 13 is selected as - 1 mm / 10 = - 0.1 mm. Since the axial advance in each partial section or partial interval is selected to be constant in the exemplary embodiment in FIG. 13, since T i + 1 - T i is selected to be the same or equidistant for all i, the result is P as the slope becomes smaller_i and thus decreasing axial feed speed increasing rotation angle intervals f i + 1 - f i f i + 1 - f i> f i - f i -1 in the rotation angle range ^ f in the braking steps S i. I.e. the angle of rotation distance f₂ - f₁ is smaller than the angle of rotation distance f₃ - f₂ and the angle of rotation distance f_{i + 1} - f_i is greater than the angular distance f_i - f_{i -1}. The last subsection between the rotation angle values f covers the largest angular distance or angular range₁₀ - f₉. This corresponds to a continuous step S in each subsection or braking step_i slowed braking process. During the braking movement AB, the time dependency of the rotational speed d f / dt and the axial feed rate dT / dt is selected or controlled or programmed in such a way that the tool 2 at the reversal point UP = (f_n, Tn) or (f10, T10) comes to rest, i.e. d f / dt = 0 and dT / dt = 0 at f = f_n or T = T_n or if f = f₁₀ or T = T₁₀. The reduction of the rotational speed d f / dt and the axial feed speed dT / dt to 0 depending on the time t can, for example, take place continuously during the braking movement AB or, for example, only in the last braking step Sn or S10. The curves of the graphs in the braking steps S1 to S10 of FIG. 13, which are actually not exactly linear, but rather somewhat rounded, follow physically from the inertia the drive system, in particular the control, including its interpolation routines for smoothing the transitions, and the machine drives and the inertia of the moving components. Represented in an idealized manner or stored in the programming of the braking movement itself, however, the described sequence of linear functions or strung together linear sections with gradually decreasing gradient, i.e. gradually decreasing constant feed speed, results in the individual braking steps S._i for example S.₁ to S.₁₀. FIG. 14 shows an exemplary embodiment of how, in the first reversing phase, starting from the reversal point UP, the same dependency or function T (f) is used in the opposite order for the acceleration movement BB reversing the braking movement AB, for example according to FIGS. 12 and 13 can. However, functions T (f) and sub-steps other than those in FIG. 5 can also be used, which preferably relate to point (f₀, T₀,) at which the braking movement AB began or the first work phase ended, so that the correct threading point for the tool for moving back through the thread 50 can be reached. Preferably, starting from the final angle value f_n or f₁₀ in the reverse order initially an acceleration phase as the first reversing phase with an acceleration movement BB carried out with the same incremental steps. However, these steps are now acceleration steps S j with n + 1 j j n 2 n, beginning in FIG. 14 with S11 to S20 for n = 10. Associated with each of these acceleration steps S j is an associated angle of rotation interval [f10, f11], [f11, f12],…, [fj -1, fj], [fj, f i + 1],… [f ^ ^, f20 ], where fj from the first reversing phase is simply f_i from the second work phase corresponds if one sets i + j = n. The slope parameters also remain the same, only in the reverse order, ie in FIG. 5 they are run through from P10 via P9, P8 to P1 for the subsections of the control curve according to FIG. 13 from right to left until the depth value T is reached₀ is achieved. According to FIG. 14, the new angle value f₁₁ temporally after the angle value f₁₀ assumed and corresponds to the interval [f₁₀, f₁₁] the Interval [T10, T9] with the thread pitch P10 and the subsequent angular interval [f11, f12] the penetration depth interval [T9, T8] with the corresponding thread pitch P₉ etc. up to the last section of [f_19th ^ ^ f_20th] according to [T₁, T₀] with the thread pitch P1. Subsequently, in the reverse direction of FIG. 12, the linear section of the curve from f0 to f = 0 corresponding to the penetration depth T from T0 to T = 0 is traversed. The axial feed speed corresponding to the slope of the straight line in FIG. 1 during the backward movement is now again P / 360 ° with the opposite direction. As a result, the tool is guided in reverse through the thread generated in the forward movement, without the thread turn being damaged in the thread. The backward movement is synchronized in the same way as the forward movement, only with the opposite direction of rotation, so that the angle f differs from the angle f_n its value decreases again backwards up to f = 0 and also with a reversed axial feed rate the thread depth now increases from T = T0 to T = 0 seen mathematically. Using the same control curve or function T (f) as in the forward movement VB in the two working phases also in the backward movement RB in the two reversing phases has the advantage, on the one hand, that the tool 2 can be controlled with exact positioning or movement is in the correct position, in particular when threading into the thread 50, and in this way the forces during reversing can be kept very low and / or a high return or extension speed is made possible. In one embodiment of an implementation of the described dependencies or functions for T (f), the values of the penetration depth T are used as input parameters measured or specified by the controller or programming, and the associated values of the angle of rotation f ^ result from the dependency using the assigned slope parameters P. and P i. A CNC program for tapping or thread forming can therefore be selected, in particular with a G33, in particular G331 and G332, path condition with a thread pitch to be entered, and a sequence or set of Values for the penetration depth can be specified at which a switch is made to a new thread pitch parameter, the thread pitch parameter being retained until the next value of the penetration depth. A sequence would be e.g. work movement: ^ With the penetration depth T = 0 select the thread pitch parameter P and keep it until T = T₀ at. A speed or rotational speed is set. ^ At T = T0 change to the thread pitch parameter P1 and keep it until T = T1. ^ At T = T i change to the thread pitch parameter P i + 1 and keep this up to T = T i + 1 for all i with 1 £ i £ n. ^ Reduce the rotational speed or speed to 0 at T = Tn and preferably for the reversing movement: ^ At T = T_n reverse the axial feed movement and the rotary movement with a set rotational speed or rotational speed and start again in the opposite direction with the thread pitch parameter Pn and maintain this until T = Tn-1. ^ At T = T j change to the thread pitch parameter P j and keep it until T = T_{j -1} with for all j as a descending index with 1 £ j £ n-1. ^ At T = T₀ choose the thread pitch parameter P and keep it until T = 0. Even if this embodiment of the working movement in the second working phase and / or the reversing movement in the first reversing phase, which corresponds in particular to a linear interpolation, has advantages due to its simple implementation in existing machine programs, according to the invention in FIG all embodiments also have other dependencies or functions or interpolations can be provided in individual sub-steps or sub-intervals for the relationship between T and f, or combinations thereof. In the linear interpolation described, the linear curve sections or graph sections are continuously added to one another, i.e. the starting points (fi, T i) of each interval correspond to the end points of the previous interval and, for the first interval, the end point (f0, T0) of the linear graph of the profit de-generation. These connection points are also referred to as support points. In all embodiments or interpolations, instead of linear sections, curve sections or graph sections can also be selected that are continuously differentiable juxtaposed (or: linked, connected with one another). This means that not only does the starting point of each interval coincide with the end point of the previous interval, i.e. a continuous transition takes place at the connection points between the intervals, but also that the graph sections or their functions can also be differentiated in these connection points and their derivation have the same value. As a result, smooth or continuously differentiable transitions between the graphs in the individual deceleration steps or intervals are achieved, which is beneficial to the sequence of movements. The transition in the angle of rotation f₀ from the thread generating movement in the first working phase to the braking movement AB in the second working phase or then preferably also from the first reversing phase to the second reversing phase is preferably continuously differentiable or selected with the same slope. Examples of functions that are continuously differentiable for one Polynomials of degree higher than 1, in particular third degree, such as, for example, cubic splines, are suitable for interpolation. Spline interpolation can be used here. Using a 3rd degree polynomial function as a spline function T (f) = a₃ f³ + a₂ f² + a₁ f + a₀ With the general conditions usual for spline interpolation, for example, a function that is continuous up to the third derivative can be created. Furthermore, a continuous, in particular strictly monotonically or also monotonically decreasing function for the braking process or at least a predominant part of the braking steps S can also be used_i, for example an exponential function or logarithmic function, can be used. For example, the following exponential function can be used: ^^ ^ ∙ ^^ ∙ ^ ^ = - ^ + 1; where fd is the pitch diameter and x is a running natural number. The theoretical curves or functions described can in particular be mapped by a corresponding number of individual NC control data records. In a further embodiment of an implementation of the described dependencies or functions for T (f), the values of the angle of rotation f ^ are used as input parameters measured or specified by the controller or programming, and the associated values of the penetration depth T result from the dependency - ability by means of the slope parameters P and P i. In a third variant, the time can also be specified as an input parameter and the values of the angle of rotation f (t) and the penetration depth T (t) result from the dependence on time t and the dependence on each other by means of the slope parameters P and P i. In one embodiment, the control or synchronization can take place in an open regulating or control circuit without measuring the process variables, penetration depth and angle of rotation. A penetration depth value is assigned to each angle of rotation value by means of a table of values or by calculation according to the stored formulas, and the rotary drive and axial drive are controlled accordingly. In a further embodiment, at least one of the two process variables penetration depth and angle of rotation can also be measured, and the measured values can be fed back into the control system in order to control, for example, according to the target curve shown in FIG - real. The angle of rotation f is generally determined in the area of the drive, in particular the drive spindle, by means of angle sensors or measurement of physical quantities that are clearly related to the angle of rotation. In principle, however, it is also possible to measure the angle of rotation directly on tool 2. The penetration depth T can be measured by axial position sensors and here again generally on the drive, in particular the drive spindle, or in a special embodiment on the tool or workpiece itself. In further embodiments, an equalization step or constant circulation step can also take place in the second work phase, meanwhile the penetration depth T (f) = const. is or at least no further feed movement is carried out in the forward direction. The direction of rotation of the rotary movement preferably remains the same during the equalization step, ie it is not reversed. In one embodiment, when the maximum penetration depth ^ T is reached at an angle of rotation f_n-1 the corresponding value T (f) for the subsequent step S_n up to the angle of rotation f_n held constant at the reversal point UP, i.e. T (f_n-1) = Tn-1 = Tn = T (f_n). In a further embodiment, the maximum penetration depth ^ T is already at an angle of rotation f_n-2 with the corresponding value T (f_n-2) = Tn-2 reached. Now the value T (f) for the subsequent step Sn-1 up to the angle of rotation f_n-1 again reduced, i.e. the axial feed direction reversed, and the penetration depth to the value T (f_n-1) = T_n-1 <T_n-2 reduced. The tool therefore runs with a slight reversing feed in the circumferential groove. This defined movement in the negative T direction away from the bottom of the hole can be advantageous in order to To further improve the catch groove in terms of screwability. From the angle of rotation f_n-1 becomes the corresponding value T (f) again for the subsequent step Sn up to the angle of rotation f_n held constant at the reversal point UP, i.e. T (f_n-1) = T_n-1 = T_n = T (f_n). However, especially when the circumferential groove has already been (largely) created, a relatively large and / or rapid return movement and / or an axial back and forth movement of the tool during leveling can also take place, which can also have an axial advance per 360 ° which is even greater than the thread pitch P. The tool and its thread teeth thus rotate in step Sn on a circular path or cylindrical path without a slope or even in step Sn-1 with a positive slope again by a small amount outwards in the workpiece. This movement serves in particular to level out the circumferential groove and to clean the surface of the workpiece, to evacuate the created threaded hole as completely as possible from chip material and, if necessary, to relieve tension between workpiece and tool that were previously built up by the machining forces. The step S_n as the last step of the braking movement AB as well as the penultimate step S_n-1 can therefore also be referred to as an equalization step. The total angle of rotation f_n - f_n-1 of the equalization step S_n or f_n - f_n-2 of the equalization step Sn and Sn-1 can be freely selected within wide limits, for example between 180 ° and 2000 °, and is generally selected to be larger, for example 3 times larger, than the angle of rotation f_n-1 - f₀ or f_n-2 - f₀ of the previous monotonically falling section (transition area). In the reversing movement RB, for example, the equalization step can also be partially or completely omitted in the first reversing phase. By means of the measures according to the invention, advantageous sequences of movements can be achieved in the transition into the free cut (circumferential groove) and in the free cut itself. The working speed of the tool can be as high and constant as possible. The machine (including control) can do the movement map in a highly dynamic manner. A geometry that can be screwed through can also be created in the cutout or the circumferential groove. If you look at the conditions on the machine, you can see that there is a physical inertia in the system as well as an inertia in the drives and in the control system. In order to keep the speed from the thread high in the undercut, ie the circumferential groove, the machine is enabled, preferably with a high one, in particular by a constant movement path of the z-axis (variable T) and rotation axis (variable f) Track speed to realize this movement. This then results in a high and constant speed of the effective tool teeth and cutting edges. This, in turn, is beneficial for uniform machining. In order to program the machine, the theoretical trajectories can be transferred to corresponding NC blocks. Here, slight deviations or approximations (in the form of, for example, compound helical movements) can occur. In the technical implementation of a thread production process like the present one, the time dependence of the penetration depth T = T (t) and the angle of rotation f = f (t) or the speed or frequency n = n (t) on the time t This defines the path speed v (t) (circumferential speed, machining speed, feed speed, cutting speed) resulting on the workpiece, ie the speed in the tangential direction to the trajectory. The path speed v (t) depends on the radius r and thus the thread hole diameter, on the one hand, and the speed of rotation ^ (t) = df (t) / dt = 2 ^ n (t) according to the vector relationship v = rx ^ and is therefore larger for larger radii r at the same speed n, for example larger for M8 threads (r = 4 mm) than for M6 threads (r = 3 mm). Ideally, an at least approximately constant maximum web speed vmax should be achieved or maintained for as long as possible or for as long a period of time as possible during the process. This applies in particular to the braking movement or undercut movement AB. The tool is generally set to this maximum value v in terms of its performance and geometry_Max optimized. This maximum path speed v_Max corresponds to an at least approximately constant maximum speed n_Maxwhich, however, depends on the radius or diameter of the tool, as already described. According to the EMUGE manual, pages 282 to 283, different cutting speeds should also be selected for tapping, depending on the material of the workpiece and the material of the tap (solid carbide or HSS), e.g. from 40 to 100 m / min. in non-hardened steels and from 5 to 80 m / min. in cast iron and from 10 to 60 m / min. in aluminum alloys for the various types of taps specified there. After extensive tests and investigations by the inventors, values for the web speed v_Max from a value range from 57 m / min to 189 m / min, in particular from 85 m / min to 132 m / min, shown to be particularly expedient, in particular in aluminum materials. The following preferred speed ranges in rpm (1 / min = 1/60 Hz) for the maximum speed are derived from these web speed ranges. With an M6 thread (diameter 6 mm), the maximum speed nmax of the tool is between 3,000 rpm and 10,000 rpm, preferably between 4,500 rpm and 7,000 rpm. With a different thread diameter, the speed or the speed range changes according to the ratio of 6 mm to the other thread diameter, e.g. with M8 instead of M6 by a factor of 6/8 = 0.75. With an M8 thread (diameter 8 mm), for example, the maximum speed nmax of the tool is between 2,250 rpm and 7,500 rpm, preferably between 3,375 rpm and 5,250 rpm. Technically, as already stated, a primary target specification or process condition is as long as possible, both during thread generation, i.e. the first work phase with the work movement VB, and, above all, during the undercut movement, i.e. the second work phase with the braking movement AB Time to achieve or keep the desired path speed and thus the maximum speed as constant as possible. In other words, the longest possible periods of time during the work movement, including the second work phase (undercut movement), should ensure the longest possible plateau with the maximum speed in the time-dependent function of the speed n (t). In this way, the process can be operated as long as possible at the maximum speed that is optimal for the tool and excessive forces and accelerations on the tool can be avoided. In addition, in a further target specification or process condition, the maximum speed should already be reached when entering the workpiece at a specified safety distance. It has now surprisingly been found that at the stated preferred maximum speeds of 4,000 rpm to 6,000 rpm, especially for M6 and M8, even with this high-end machine equipment, there is no constant maximum speed in the undercut movement, and thus no constant maximum speed Path speed could be achieved, which led to reduced tool life and sometimes even tool breakage. The following error, i.e. the offset between the setpoint and the actual value of the axis position, increases with increasing speed in machine tools. This error can be counteracted by increasing the Kv factor, which indicates the speed at which the following error is closed. However, there are limits to the increase in the Kv factor, since otherwise the machine's control system will become unstable, overshoots will occur and the machine will begin to vibrate. In one embodiment, the invention is based on the idea of interposing or arranging a transmission unit between the spindle of the machine and the tool, which converts the speed of the machine spindle to a higher speed on the tool with a predetermined transmission ratio of at least 1: 3 . The speed at the machine spindle is equal to the product of the transmission ratio and the speed of the tool. With this measure, it was surprisingly possible to achieve a sufficient speed plateau with the maximum speed both during the first work phase (thread generation) and during the second work phase (undercut or circumferential groove generation). The transmission ratio is generally chosen between 1: 3 and 1:10, in particular between 1: 4 and 1: 8, preferably between 1: 4 and 1: 5. It turned out that higher gear ratios did not bring any significant further improvements. If machine tool controls should also achieve the stated objectives, even without a translation unit, then such designs also fall under the implementation of the invention and its scope of protection. In exemplary embodiments with reference to FIGS. 15 and 16, the difference with and without a translation unit becomes clear. An exemplary embodiment for the translation unit used is shown in FIG. The thread generation cycle of FIG. 15 was carried out according to the invention with a translation unit between the machine drive or the machine spindle of the machine tool and the tool. The transmission ratio of the transmission unit, which corresponds to the ratio of the speed or the rotational speed of the drive, here the machine drive or the machine spindle, to the rotational speed or the rotational speed of the output, here the tool 2 or its tool holder, is included chosen less than one, ie the translation takes place quickly. In the example shown in FIG. 16, a transmission unit with a transmission ratio of approximately 4.4 was selected by using a speedsynchro modified according to the invention^® the applicant was used. The maximum spindle speed was 1,020 rpm = 17 1 / s = 17 Hz set, corresponding to a speed of the tool of 4,500 1 / min = 75 1 / s = 75 Hz The thread generation cycle of FIG. 16 was carried out without a translation unit between the machine spindle of the machine tool and the tool, i.e. the speed of the spindle corresponded to that of the tool. A maximum spindle speed of 4,500 rpm = 75 1 / s = 75 Hz was set. FIGS. 15 and 16 show empirically determined time dependencies or controls of the penetration depth T = T (t) or z-axis coordinate on the one hand and the speed n = n (t) as a function of time t over the entire thread generation cycle between the entry point EP and the reversal point UP and back again. The penetration depth T (t) = T (f (t)) results as a function of time t due to the selected dependency T (f), which has already been described in detail. The speed n (t) depends on the angular speed ^ = ^ (t) = df / dt, which corresponds to the first time derivative of the angle of rotation of the angle of rotation f = f (t), together as follows 2 ^ n (t) = df / German The angular speed ^ or the speed n (t) and the axial speed v (t) are synchronized again, in particular according to an embodiment according to FIG. 12. The speed n (t) in FIG. 15 shows two different speeds over time plotted, on the one hand the speed nW (t) of the tool 2 and on the other hand the speed n_S.(t) the machine spindle. The two speeds n_W.(t) and n_S.(t) are over the transmission ratio I = n_S.(t) / n_W.(t) the translation unit linked together. The transmission ratio I is generally selected to be greater than 3; in the present exemplary embodiment in FIG. 16, the transmission ratio I of the transmission unit is approximately I = 4.4. In FIG. 16, on the other hand, only a speed n (t) is plotted against time, namely the speed nW (t) of the tool 2, because the speed nW (t) of the tool 2 and is due to the lack of a transmission unit the speed nS (t) of the machine spindle is the same, ie nS (t) = nW (t). On the time axis of time t in FIG. 15 and FIG. 16 there are eleven times t₀ until t₁₀ applied. The earliest time t₀ corresponds to the start of the thread creation cycle at entry point EP. The entry point EP is at T (t₀) on the workpiece surface and is spaced by a safety distance here, for example - 2 mm from T = 0 mm, at which the movement in the z-axis begins. The first work phase of the work movement VB, in which the thread is generated, begins at time t0. Here, the penetration depth T (t) is synchronized with the angle of rotation f (t) or the speed n (t) via the thread pitch, as shown in FIG. 12, for example. FIGS. 5 and 6, for example, in which the thread generation area 4 generates the thread 50, fall into this time interval. This first working phase ends at time t2 and the undercut movement or braking movement AB changes into the second working phase. Here at T (t2) the thread depth is T._G reached, which in the present case is, for example, about 11 mm. In the second work phase between time t₂ and the time t₅ the braking movement or undercut movement AB takes place, which ends at the reversal point UP. The penetration depth T (t) increases, becoming significantly slower, by the penetration depth range DT = T (t5) - T (t2) down to the lowest value T (t5) at the reversal point UP (in terms of amount), which in the example shown - 14 mm. The thread hole depth TL is reached here. Starting at time t2 to time t5, which corresponds to the reversal point UP, the braking process or the undercut movement to produce the circumferential groove (s) or undercuts, in particular 51 in FIGS. 1 and 10 and 51 and 52 in FIG. 11, takes place , in particular the braking movement AB according to FIG. 12 and FIG. 13 and / or the braking movement with the dependency according to the invention between the penetration depth T = T (f) and the angle of rotation f (not to be confused with the curve T (t) in FIG. 15 and 16). While 12, the penetration depth changes by DT and the angle of rotation by D f .9 mm - 0.05 mm (thread itself has P = 1 mm). Machine-internal routines usually interpolate the commands entered into a continuous curve for each axis. As a result of the reduced gradients in the undercut movement, in particular the chip root in the drill base is reduced in size until it no longer represents an obstacle in the backward movement. At the reversal point UP, the penetration depth T (t) reaches its deepest and largest value TL in terms of absolute value, and the angle of rotation f (t) likewise reaches its largest or widest value fL. The axial speed v (t) = dT / dt and the speed n (t) = df / dt / 2 ^ each momentarily assume the value zero at the reversal point UP, i.e. tool 2 is momentarily at a standstill here, for example as shown in FIG. From the reversal point UP at the point in time t5, the reversing movement RB of the tool 2 begins, which again enters a first reversing phase with the acceleration movement BB, which lies between the points in time t5 and t8, and a second reversing phase, which occurs between the points in time t8 and t10 is divided. At time t10, the workpiece surface is reached again and T (t10) = T (t0), in the present example -2 mm. In the exemplary embodiments shown in FIGS. 15 and 16, without loss of generality, the control of the feed movement VB and the reversing movement RB is designed essentially symmetrically to the reversal point UP, ie the graphs for the penetration depth T = T (t) essentially axis-symmetrical or mirror-symmetrical to a vertical axis of symmetry running through time t5 of the reversal point UP and the graphs of the speeds nW (t) and nS (t) are each essentially point-symmetrical to point (t5, 0) when reversing - point UP. In the exemplary embodiments in FIGS. 15 and 16, the dependency or synchronization of the penetration depth T = T (f) on or with the angle of rotation f with a varying thread pitch parameter in the undercut movement AB according to FIGS. 12 and 13 and 14 was selected. As can be seen immediately in FIGS. 15 and 16, the real temporal progressions of the speed nW (t) differ despite the resulting maximum speed n theoretically programmed in the machine control_Max on the tool, here 4,500 rpm, quite considerably. This is explained in more detail below. In the embodiment according to the invention with a transmission unit according to FIG. 15, the machine control increases the speed n_W.(t) according to the specified maximum angular acceleration from the point in time at T = 0 mm and already reaches the maximum value ns.max of the speed of the machine spindle and the corresponding translated maximum value of the speed of the tool shortly before the point in time t0 at the entry point EP. This maximum value of the speed of the tool now reaches or corresponds to the theoretical, programmed maximum speed nmax of the tool, here the full 4,500 rpm, corresponding to ns.max = I nmax = 1,020 rpm for the spindle. This maximum speed n_Max is now over a plateau with a time interval Dt₁ between times t₀ and t₁ held constant, i.e. n_W.(t) = n_Max or according to n_S.(t) = n_{S, max} in the time interval between t₀ and t₁ the interval length Dt₁. At time t4, the speed nW (t) decreases again to a local minimum at a minimum speed nmin, which is already within the braking movement AB, ie here shortly after time t2. The speed difference between maximum speed nmax and minimum speed nmin is denoted by Dn, i.e. Dn = nmax - nmin and should not exceed 0.8 nmax. Dn depends on the machine and machine control used. Now after reaching the minimum speed n increases_min as a result of the control of the undercut movement AB, the speed n_W.(t) immediately starts again and reaches again for the second time the maximum speed nmax at time t3, which is kept constant over a second plateau with a time interval Dt3 between times t3 and t4, ie nW (t) = nmax or correspondingly nS (t) = nS, max in the time interval between t3 and t4 of the interval length Dt3. The time course of the speed n_W.For other values, (t) is for the transmission ratio I, in particular in a value range from I = 3 to 8, and for other values for the maximum speed n_Max in particular in a value range from 3,000 to 10,000 rpm, also in the various combinations, qualitatively the same. In particular, the two plateaus Dt₁ and Dt₃ with the intermediate time interval Dt2. The absolute values of the interval length of the second plateau Dt3 depend on the transmission ratio I and the maximum speed nmax and also on the machine control. In particular, the interval length Dt3 of the second plateau can be selected in a range from 0.01 s to 0.25 s, in particular 0.02 s to 0.13 s. From time t_4th takes the speed n_W.(t) to 0 at the reversal point UP at the time t₅ from. The intermediate time interval Dt₂ between times t₁ and t₃, which lies between the two plateaus, i.e. the time periods Dt1 and Dt3 with maximum speed nmax, is also machine-dependent and should generally not be avoidable, but should be kept as short as possible. The absolute values for the interval length of the intermediate time interval Dt₂ for the different gear ratios I and maximum speeds n_Max lie, in particular between 0.05 s and 0.15 s, preferably between 0.06 and 0.10 s, that is to say, as a rule, they do not vary as strongly as in the case of Dt₃. Among other things, the ratio Dt₂ / German₃ of the time interval Dt2 between the plateaus and the time interval of the second plateau Dt3, because the time interval Dt2 of the first plateau is also dependent on the thread length. In general, the ratio Dt2 / Dt3 is in a range from 0.3 to 3.4 for the various transmission ratios I and maximum speeds nmax, in particular in a range from 0.5 to 2.4. This course of the speed n_W.(t) during the work movement between times t₁ and t₅ is repeated, as can be seen in FIG. 15, in the reversing movement between times t₅ and t₁₀ Point-mirrored at the reversal point UP with two plateaus of maximum speed - n_Max, namely the plateau Dt₃ between times t_6th and t_7th and the plateau Dt₁ between times t₉ and t₁₀ and the lower speed range in between with the absolute speed minimum - nmin between times t7 and t9. In the embodiment without a transmission unit according to FIG. 16, the machine control increases the speed nW (t) according to the specified maximum rotational acceleration from the point in time at T = 0 mm via the point in time t0 at the entry point EP up to the point in time t1 until a point local and global maximum at this point in time t₁ is reached, but without a plateau, i.e. without a time interval in which the speed remains at its maximum value. Rather, the maximum value of the speed n_W.(t) leave immediately, i.e. the speed n_W.(t) decreases from time t₁ immediately off again. Furthermore, the real maximum value of the speed n is reached_W.(t) below the programmed maximum speed n_Max. At the point in time t3, the speed nW (t) reaches a local minimum nmin which is already within the braking movement AB, that is to say here shortly after the point in time t2. Now, as a result of the control of the undercut movement AB, the speed nW (t) increases again and reaches a second local maximum at time t_4th and then only increases to 0 at the reversal point UP at time t₅ from. The maximum at time t_4th is smaller than the maximum at time t₁ and is punctual, i.e. here, too, no plateau with constant speed develops. This course of the speed n_W.(t) during the working movement between times t1 and t5 is repeated in the reversing movement between times t5 and t10, mirrored at the reversal point UP, with two absolute maximums at times t6 and t9 and an intermediate amount Minimum - nmin at time t8. Even in the reversing movement, the maximum speed in terms of absolute value - nmax is not reached and the desired speed plateaus are not established. The flank rises or slopes in the speed are limited or determined in both exemplary embodiments and generally by the maximum rotational acceleration of the machine spindle. In the case of designs with the transmission unit as shown in FIG. 15, improvements in the thread quality, machine wear, tool load and, as a result, probably also the tool life, were found compared to designs without a transmission unit as shown in FIG. An embodiment of a translation unit can be achieved by a modification of the Speedsynchro^® be formed by the applicant. In contrast to the known one, a rigid coupling is implemented without length compensation by means of elastomers in order not to endanger the accuracy of the control steps carried out in the vicinity of the reversal point UP. It has now been shown that with the braking or undercut movement AB or circumferential groove generation according to the invention, cleaning of the remaining material residues such as chip roots or form bead takes place before the tool movement is reversed at the reversal point and therefore no longer loads too much during the reversing movement the thread teeth occurs. As a result, breaks in thread teeth made of the brittle, hard materials can be avoided and thread generation areas or thread teeth, in particular on separately manufactured, replaceable thread generation elements made of hard metal or another similarly brittle material, can be used. Thus, in or through the method according to the invention with the axial thread generation movement with the integrated braking or undercut movement AB or circumferential groove generation now practically any axial thread generation tools, i.e. taps or thread taps or combinations thereof or other cutting and non-cutting axially working threads - Generation tools can be used, especially those with threaded teeth Hard metal or another brittle material, in particular thread teeth on separate thread generating elements that are releasably attached to a carrier body or holder. The thread generating tool can now in embodiments, as shown for example in FIGS. 17 to 22, have a carrier body and a thread generating area with one or more thread teeth distributed over one or more thread generating element (s) detachably or exchangeably attached to the carrier body. In other embodiments, the thread generating tool, as shown for example in FIGS. 23 to 26, can be designed monolithically, the thread generating area with one or more thread teeth on a base body being made in one piece with this, for example by machining such as grinding. The support body or the base body can also have a neck, i.e. the diameter tapering or decreasing continuously or in steps towards the thread generation area. 17 shows a thread generating tool, in particular a tap, with three thread teeth 11, 12 and 13 at the corners of a plate-shaped thread generating element 10 having a triangular basic shape. The thread generating element 10 is delimited on the outside by three flat side surfaces 14 reproducing the triangular shape which extend as far as the rear areas of the flanks F1 to F3 of the thread teeth 1 to 13. At the front, the open areas F1 to F3 merge into thread cutting G1 to G3 of the thread teeth 1 to 13. The thread cutting edges G1 to G3 lie on respective rake faces which are each formed by a flute 15 which is adjacent to the respective thread tooth 11 to 13 and preferably runs axially or straight. By means of a central fastening screw 27 guided axially through a central opening in the thread generating element 10, the thread generating element 10 is fastened at the front to the end face or end face 22 of a carrier body 20. The The tool axis A runs centrally through the support body 20 and the thread generating element 10. FIGS. 18 to 21 show an exemplary embodiment of a thread generating tool with several, here for example six, thread generating elements 71 to 76 that can be used multiple times due to multiple thread cutting. shows. The thread generating elements 71 to 76 have, in an approximately rectangular, symmetrical and plate-shaped basic shape, four thread cutters G at the four corners with respective rake faces in front. Each of these thread generating elements 71 to 76 is inserted in an associated receptacle 91 to 96 of the carrier body 20 on its end face 22 and can be detached and exchanged on the carrier by means of a fastening screw (not shown) guided through a central opening in the thread generating element 71 to 76. gerkkörper 20 attached. The receptacles 91 to 96 can be adapted to the thickness of the thread generating elements 71 to 76, so that the front surfaces of the thread generating elements 71 to 76 are essentially flush with the end surface 22 of the carrier body 20. By rotating through 180 ° or turning the thread generating elements 71 to 76, these are four times. i.e. can be used with one of the four thread cutting edges G in the manner of an indexable insert. In each case one thread web with two thread cutting edges G can forms a thread tooth GZ. The thread teeth GZ of the various thread generating elements 71 to 76 again lie on a helix with the thread pitch P, preferably each axially spaced by DP and equally spaced in the circumferential direction by a pitch angle D ^. However, designs of thread generating elements 71 to 76 with only three or two or even only one thread cutting edge G and also with basic shapes other than rectangular or plate-shaped and also with a number other than 6 are also possible. The outermost radial distances between the active thread cutting G of the thread teeth of the thread generating elements 71 to 76 are denoted by r1 to r6 and preferably increase in the opposite direction to the direction of the winding, that is to say r1 <r2, r2 <r3, ... to r5 <r6. In FIG. 22, a thread generating tool with a thread generating element 80 on an end face 22 of a carrier body 20 is now shown. The plate-shaped thread generating element 80, again designed as a working head, has a star-shaped basic shape with, for example, eight thread teeth 81 to 88, which are arranged, for example, equidistantly around the tool axis A running centrally through the thread generating element 80 and the carrier body 20 and in front of which again by a flute a rake face is formed. By means of a central fastening screw 27 guided axially through a central opening in the thread generating element 80, the thread generating element 80 is fastened at the front to the end face 22 of the carrier body 20. The thread generating element is designed in FIG. 17 as well as in FIG. 22 as an end working head or threaded head with the complete thread generating area or all of the thread teeth. The carrier body 20 can therefore be of a very simple design and, for example, as shown in FIG. 17 or 22, be a body that is easy to manufacture and has a cylindrical shape or a shaft shape with respect to the tool axis A and whose half diameter is smaller than the radial distance between the thread teeth and the tool axis A. Coolant and / or lubricant outlets 26 can be provided on the lateral surface of the carrier body 20. In other embodiments, as shown in FIGS. 18 to 21, a plurality of thread generating elements, which are separately fastened to the carrier body and detachably attached, are provided, which are distributed around the tool axis A in the circumferential direction and are arranged at a distance from one another. Each thread generating element can have an active or working thread tooth or thread cutting edge, but also have additional non-active thread teeth or thread cutting as reserves, but which become active by turning and / or remounting the thread generating element on the carrier body. In addition to a With a detachable attachment, however, a non-detachable attachment of the thread generating element to the carrier body is also possible, for example by soldering or printing in 3D printing. Additional form-fit connections, not shown, can also be provided for additional anti-rotation locking or, if necessary, also axial locking at the connection point between the carrier body 20 and the thread-generating element, for example 10 according to FIG. 17 or 80 according to FIG. 22. In the exemplary embodiment according to FIGS. 23 to 26, a monolithically produced front region of a tap is shown, which is thus essentially formed from one material. In a base body, which has a cylindrical basic shape, several, in particular five, successive threaded teeth Z1 to Z5 are separated from one another by several, for example five, separating grooves 25 running axially to the tool axis A, which thread teeth Z1 to Z5 follow one another and extend around the tool Axis A are arranged and have thread cutting G in the direction of the winding and open spaces F behind. Behind the thread generation area formed from the thread teeth Z1 to Z5, the cylindrical outer surface of the base body is denoted by 31. In front of the thread generating area formed from the thread teeth Z1 to Z5, a cylindrical guide area 33 is now additionally formed for guiding the tool on the core hole wall in the core hole 36. The guide area 33 merges with the front side 32 of the base body via a front bevel 34. In the end face 32 there can be a central outlet for coolants and / or lubricants. The thread generating areas 4 and their thread teeth, in particular 41 and 42 in FIG. 1 to 10 or 11 to 13 in FIG. 17 or the G arranged in the direction of the winding at 71 to 76 in FIG. 18 to 21 or 81 to 88 in FIG. 22 or Z1 to Z5 in 23 to 26, are arranged along the helix or helical line formed according to the thread 50 to be generated with the thread pitch P one behind the other and at the corresponding pitch angles to one another and also engage in each location in the workpiece along the thread 50 one after the other . The axial distance DP of the thread teeth or their thread cutting is related to the pitch angles. If the division is even, both the pitch angles as well as the axial distances are the same, with unequal pitch they differ in size. Because of the undercut movement AB, at least its axial dimension is now lost in the thread depth due to the circumferential groove. The axial dimension of the circumferential groove becomes larger the longer the thread generation area extends along the tool axis A. It is therefore advantageous in the tool and process according to the invention to keep the thread generation area 4 or the axial distance between the first thread tooth and the last thread tooth opposite to the direction of the thread as small as possible, preferably in a range between 0.5 P and 1.5 P. The thread teeth can all be designed to cut or all to form or also to cut or form in any order or configuration. A cut or chamfer area or run-up is preferably formed in the thread generation area 4. This means that the thread profile of the thread turn 50 is successively cut or shaped from the individual thread teeth up to the complete thread profile. So the thread action profiles of the individual thread teeth are divided up and ultimately result in the complete thread profile. For example, the outer radial distances of the thread teeth from the tool axis A increase in the opposite direction to the direction of the winding, so that the thread root of the thread turn 50 is incorporated ever deeper. This is visible, for example, in the exemplary embodiments according to FIGS. 18 to 21 and 23 to 26. Because of the axially short thread generation area 4, this section or thread generating area preferably extends over the entire thread generation area and there is then no calibration or guide area with thread teeth of the same thread profile. This has the disadvantage that the tool is not guided in the core hole and the thread just created as well as a conventional thread drill. FIGS. 27 to 30 show exemplary embodiments of a division of the thread action profiles, for example in the case of the tool 2 according to FIGS. 1 to 10 or 17 to 26. The The thread profile is successively generated by superimposing individual active profiles of successive thread teeth, whether cutting or shaping. This is in particular a special design of a gate or chamfer area. There are successively added thread tooth profile surfaces ^ Ai as differential profiles of two successive thread tooth profiles, e.g. with five thread teeth ^ A1 to ^ A5, until finally the entire thread profile GP is created as a superimposed active profile. In FIG. 27, the thread tooth profiles and the differential profiles or thread tooth profile surfaces ^ Ai lie symmetrically in a trapezoidal or metric thread profile GP and increase in a geometric expansion in the form of larger individual trapezoidal or metric thread tooth profiles, so that both the thread flanks and the The thread root of each thread tooth can be worked in further. In FIG. 28, the thread tooth profiles and the differential profiles or thread tooth profile surfaces ^ Ai are again symmetrically in a trapezoidal or metric thread profile GP, but have the same pitch diameter and increase in height as individual trapezoidal or metric thread tooth profiles increase in height, so that only the thread root and the adjacent thread flank sections of each thread tooth are further incorporated. In FIG. 27, the thread tooth profiles and the differential profiles or thread tooth profile surfaces ^ Ai lie symmetrically in a trapezoidal or metric thread profile GP and increase in a geometric expansion in the form of larger individual trapezoidal or metric thread tooth profiles, so that both the thread flanks and the The thread root of each thread tooth can be worked in further. In FIG. 28, increasing triangular thread tooth profiles are initially used for the first four thread teeth, so that an asymmetrical triangular differential profile or thread tooth profile surface ^ A1 and correspondingly inclined strip-shaped differential profiles or thread tooth profile surfaces ^ A2 to ^ A4 arise. The final trapezoidal or metric thread profile GP is then made by the last thread tooth completed according to differential profile or thread tooth profile area ^ A5. 30 shows a special thread profile division for trapezoidal or metric thread profiles GP, in which two thread teeth with essentially the same size trapezoidal thread profile surfaces ^ A1 and ^ A2 are used on opposite thread flanks of the thread profile GP and then two larger trapezoidal thread profiles of the two following thread teeth again on opposite thread flanks of the thread profile GP, so that the difference profiles or thread tooth profile surfaces ^ A3 and ^ A4 arise. The final trapezoidal or metric thread profile GP is then completed by the last thread tooth according to the difference profile or thread tooth profile area ^ A5. Identical thread tooth profile surfaces, in particular ^ A1 = ^ A2 as, for example, in FIG. 30 generally mean the same volumes of the cut or shaped thread part profile of the thread 50. Identical thread tooth profile depths, in particular as in FIG. 27 and FIG usually the same chip thicknesses when cutting or indentation depths when forming the corresponding thread part profiles of the thread turn 50. In the case of differently designed and / or more or less than five thread teeth, the division can also be designed differently. In all embodiments, at least the thread teeth, the or each thread generation area or the thread generation elements, in monolithic embodiments also the entire tool, are preferably made of hard metal such as a hard metal alloy, in particular P steel or K steel or cermet, or sintered hard metal, in particular Tungsten carbide, optionally alloyed or mixed with metals or other metal carbides, or titanium nitride or titanium carbide or titanium carbonitride or aluminum oxide, or cutting ceramics, in particular polycrystalline boron nitride (PCB), or polycrystalline diamond (PCD). Due to the undercut movement, the durability and service life of these rather brittle materials are significantly increased. Alternatively, high-speed steel such as high-speed steel (HSS steel) or cobalt-alloyed high-speed steel (HSS-E steel) can also be used. The carrier body to which the thread generating element is attached can be made of any material, but preferably a material that is easier to manufacture, such as high-strength steel. In principle, it is also possible that the carrier body is made of high-speed steel such as high-speed steel (HSS steel) or cobalt-alloyed high-speed steel (HSS-E steel) or also of hard metal such as a hard metal alloy, in particular P-steel or K-steel or Cermet, or sintered carbide, in particular tungsten carbide, optionally alloyed or mixed with metals or other metal carbides, or titanium nitride or titanium carbide or titanium carbonitride or aluminum oxide, or cutting ceramics, in particular polycrystalline boron nitride (PCB), or polycrystalline diamond (PCD) or is made. Furthermore, additional coatings, in particular wear protection layers, can be applied to the tool, in particular its thread generation area or at least its thread teeth. The carrier body preferably has an internal coolant and / or lubricant supply and thus internal channels. The carrier body can be produced in various ways, including by 3D printing and / or machining. In one embodiment, preferably in the front area or as the front thread tooth, a thread tooth is provided which has a thread tooth profile with a front thread tooth profile flank and a rear thread tooth profile flank as well as a front flank flank flank directly adjoining the front thread tooth profile flank on a front thread tooth flank and a self has a rear flank free surface immediately adjoining the rear thread tooth profile flank on a rear thread tooth flank. The front flank clearance surface is exposed to the rear or set back with respect to a front thread tooth flank envelope which runs along or parallel to the helical line and through the front thread tooth profile flank. It is now the rear flank clearance with respect to a rear transverse plane which is directed perpendicular to the tool axis and runs through the rearmost point of the thread tooth profile or the rear thread tooth profile flank, offset to the front or exposed. The helical line is inclined backwards by the thread pitch angle with respect to the rear transverse plane. This exposure of the thread tooth prevents or at least greatly reduces friction of the thread tooth on the workpiece surface both on its front thread tooth flank and on its rear thread tooth flank both during the working movement and during the braking movement. Here and in the following, “front” or “front” are to be understood as following in the direction of the forward movement or the direction of winding of the thread generation area and “rear” or “rear” as in the opposite direction, i.e. opposite to the direction of the forward movement or to be understood in the direction of the backward movement or opposite to the direction of winding of the thread generating area. In embodiments, the front flank clearance surface is inclined or set back by a front flank clearance angle with respect to the front thread tooth flank envelope, which generally lies in an interval between 0 ° and 10 °, in particular between 0 ° and 2 °. In advantageous embodiments, the rear flank flank face is inclined or set back with respect to the rear transverse plane by an angle which is generally in an interval between 0 ° and 6 °, in particular between 2 ° and 5 °, and / or with respect to a rear thread tooth flank envelope that extends along which extends or runs parallel to the helix, is inclined or set back by a rear flank clearance angle which is greater than the thread pitch angle and generally in an interval between the thread pitch angle and 6 °, in particular between 4 ° and 5 °. The flank flanks can run helically, i.e. linearly in the development, or also assume (differently) curved shapes, in particular tapering even more towards one another at least in sections or tapering less towards one another. In such an embodiment, the corresponding flank clearance angle can define a boundary line or surface which is not exceeded (outwards) by the flank clearance. In a further embodiment, the thread generation area, in particular in its rear area or as the rearmost thread tooth, has at least one Thread and raker tooth on. This thread and reaming tooth has a thread tooth element with a thread tooth profile as an active profile for generating or reworking the thread in a front-side area, viewed in the direction of the winding. Furthermore, the thread and reaming tooth has a reaming element for reaming the generated thread during a reversing movement in a rear area seen in the direction of the winding, the reaming element having a reaming profile as an active profile, which preferably corresponds to the thread profile of the thread created and / or the thread tooth profile corresponds to its front area. The clearing element preferably has a clearing cutting edge which has a clearing profile which corresponds to the thread tooth profile of the thread tooth element, in particular an active profile that is the same or at least the same on the clearing profile flanks of the clearing profile as the thread tooth profile. Furthermore, in an advantageous embodiment, the clearing element has a furrowing clearing surface which is arranged downstream of the clearing edge and which is opposite to the direction of the winding, whereby the active profiles of the clearing edge and the clearing surface are superimposed to form the entire clearing profile of the clearing element. The clearing surface preferably rises radially outward in the direction of the winding and can merge into a tooth web, which in particular has a constant profile or no free surfaces, with a clearing profile head of the clearing surface and / or of the toothed web being smaller than a clearing profile head of the clearing blade is. The tooth flanks of the thread and reaming tooth can run at least predominantly or completely along associated front thread tooth flank envelopes or rear thread tooth flank envelopes or without free surfaces. In a particularly advantageous embodiment of the tool, the thread generation area has both at least one thread tooth as described and at least one thread and reaming tooth, the thread and reaming tooth being the last tooth of the thread generation area and thus the first tooth in the direction of the winding during the reversing movement. In a further embodiment, at least one thread tooth or the thread and reaming tooth has a thread cutting edge in its front area in the direction of the winding or in the thread tooth element and preferably also a thread forming surface downstream of the thread cutting edge when viewed in the direction of the thread for generating a surface with a good surface quality, with the active profiles of the thread cutting edge and the thread forming surface superimposed on the thread tooth profile on the front-side area, preferably corresponding to the thread profile. The thread formation surface can rise radially outwards in the opposite direction to the direction of the winding and preferably merge into or into the tooth web, which in particular serves as a calibration area and / or has a constant profile or no free surfaces. A thread tooth profile head of the thread groove surface and / or the tooth web can now be smaller than the thread tooth profile head of the thread cutting edge. A few characteristic advantages and features of the invention are given here again in key words: Guide thread can no longer break out - Instead of flutes, a neck can be ground that does not hinder the chips Blind hole machining with IKZ can be set so that the coolant jet is directed directly onto the cutting edge or onto the chip - This means that very deep blind holes may be possible - Very short thread runout analogous to thread milling with a screw-in undercut (hydraulic!) - No reverse cut! Chip roots are removed in the free-cutting process - constant cutting speed (analogous to the turning process) with Speedsynchro® - variable gate division (design), for example facing, lead angle also towards the rear, radius on the outside, a kind of widening on the full tooth. Preference is given to stripping combined with a cylindrical cut - degrees of freedom in the design of the cutting wedge (e.g. rake angle, chip breaker, bevel, twist, negative bevel, clearance angle) - targeted cutting edge preparation - inexpensive complete machining on CNC (monolithic GB) - cutting inserts lead to low tool costs per hole for large series - for cutting inserts: adjustable inserts for different tolerances - cutting end and / or forming end thread portions or core cutting portions possible Number of thread teeth: - At least one thread cutting tooth, a maximum of several thread cutting teeth and several grooves, arranged axially over a maximum of 3 threads - Preferably arranged axially over 0.5-1.5 x thread pitch - Preferably arranged axially over a thread - Unequal pitch in the arrangement of the teeth on the circumference - Partly or entirely additively manufactured, coated, uncoated, surface treated For cutting inserts in general: - Adjustable inserts for different tolerances - Different insert geometries, e.g. butterfly inserts or standard inserts (ISO), triangular, square, rhombic, etc. Triangular insert: - Cutting head with several cutting edges

LIST OF REFERENCE NUMERALS 2 tool 4 thread generation area 5 thread 6 workpiece 10 thread generation element 11 to 13 thread tooth 14 side surface 15 flute 20 carrier body 21 shaft 22 end face 25 separating groove 26 coolant and / or lubricant outlet 27 fastening screw 30 base body 31 outer surface 32 end surface 33 guide surface 34 end bevel 35 core hole 36 threaded hole 40, 41 thread tooth 50 thread turn 51, 52 circumferential groove 53 core hole bottom 55 thread profile 60 workpiece surface 71 to 76 thread generating element 80 thread generating element 81 to 88 thread tooth a groove length A tool axis AB Braking movement b Thread gap BB Acceleration movement c Thread profile width d Core hole diameter D Thread hole diameter F Free surface F1 to F3 Free surface G Thread cutting G1 to G3 Thread cutting GP Thread profile GZ Thread tooth M Thread center axis P Thread pitch P1 to P10 Pitch parameter RB Backward movement ^ A1 to ^ A5 stepping tooth profile RB Backward movement ^ A1 to ^ A5 step of the tooth profile S20 Acceleration step T End ring depth T _G Thread depth T _L Thread hole _{depth T 0} to T ₁₀ Depth value T _i , T _n Depth value ^ T Penetration depth range UP Reversal point VB Forward movement W Direction of thread Z Thread tooth ^ P Pitch ^ ^ Pitch angle ^ Thread pitch angle ^ Opening angle F Total angle of rotation

Df Angle of rotation range fo to F20 Angle of rotation value fί, f Angle of rotation value

Claims

Claims 1. A method for generating a thread with a predetermined thread pitch in a prefabricated core hole in a workpiece, a) in which a tool is used to generate a thread, a1) wherein the tool is around a tool axis running through the tool ( A) is rotatable and axially movable to the tool axis, a2) wherein the tool comprises at least one thread generation area (4), which with a predetermined thread pitch (P) and a predetermined direction of winding (W) of the thread (50) to be generated a tool axis (A) running through the tool and having an active profile which corresponds to the thread profile of the thread to be generated, a3) each thread generation area having one or more thread teeth, b) in which the tool is in a working movement during a first Ar - beitphase is moved into the prefabricated core hole in the workpiece, b1) wherein the working movement is a rotary movement with a predetermined planar direction of rotation around the tool axis (A) of the tool and an axial feed movement of the tool in an axial forward direction (VB) axially to the tool axis, which is synchronized with the rotary movement according to the thread pitch of the thread generation area, such that one full Rotation of the tool around the tool axis corresponds to an axial advance of the tool by the specified thread pitch, b2) wherein the thread generating area generates a thread (50) in the wall of the core hole (36) running below the specified thread pitch during the first work phase in the work movement , c) the tool being moved further into the workpiece up to a reversal point (UP) in a braking movement (AB) during a second work phase following the first work phase, c1) the axial advance of the tool based on at least one full revolution during part of the braking movement, preferably during the entire Ab braking movement, in terms of amount, is smaller than the thread pitch and is zero at the reversal point and c2) the thread generating area, in particular the thread tooth or teeth, of the tool generating at least one, in particular closed or annular, circumferential groove (51, 52) in the wall of the core hole (36) in the workpiece during the braking movement.

2. The method according to claim 1, in which a) the tool has a carrier body (20) through which the tool axis runs, and at least one thread generating element, in particular produced separately from the carrier body, which is fastened to the carrier body, in particular particular is fastened interchangeably or detachably, b) wherein each thread generating element has at least one thread generating area.

3. The method according to claim 1 or claim 2, in which the or each thread generating area is arranged on a front end area of the tool and / or in which the or each thread generating element is arranged on a front end area of the carrier body, preferably on an end face (22) of the carrier body is attached.

4. The method according to claim 2 or claim 3, in which the thread generating element is designed as an end-face threaded head with the complete thread generating area or all thread teeth, the tool axis running centrally through the carrier body and the thread generating element, the thread generating element in particular by means of a central fastening screw (27) guided axially through a central opening in the thread generating element is fastened to the front of the end face of the carrier body,

5. The method according to claim 4, wherein the thread generating element has a triangular basic shape with three thread teeth (11, 12 and 13) with thread cutting (G) and open areas (F) at the corners and / or is plate-shaped and / or after is delimited on the outside by three flat side surfaces (14) which reproduce the triangular shape and which extend in particular up to the rear areas of free surfaces (F1 to F3) of the thread teeth, and / or has flutes (15) adjoining the respective thread teeth (11 to 13) and preferably axially extending.

6. The method according to claim 4, wherein the thread generating element (80) has a star-shaped basic shape and / or is plate-shaped and / or has several, in particular eight, thread teeth which are arranged around the tool axis and in front of which a flute is formed.

7. The method according to claim 2 or claim 3, in which several thread-generating elements are attached separately to the carrier body and are distributed around the tool axis A in the circumferential direction and are arranged at a distance from one another.

8. The method according to claim 7, wherein the or each thread generating element has a working active thread tooth or a working active thread cutting edge and additionally at least one, in particular one, two or three, further inactive thread teeth or thread cutting edges which, by loosening the releasable fastening, turning and / or rotating the thread generating element and re-fastening it to the carrier body, becomes an active working thread tooth or thread cutter.

9. The method according to claim 8, wherein the or each thread generating element in an approximately rectangular or triangular symmetrical and plate-shaped basic shape has four or three thread cutters (G) at the four or three corners with respective upstream rake faces.

10. The method according to any one of claims 7 to 9, in which the or each thread generating element (71 to 76) is inserted in an associated receptacle (91 to 96) of the carrier body (20), in particular on its end face (22), and is detachably and exchangeably fastened to the carrier body in particular by means of a fastening screw guided through a central opening in the thread generating element, with the receptacles preferably being adapted to the thickness of the thread generating elements so that the front surfaces of the thread generating elements are essentially flush with the end face (22) of the carrier body.

11. The method according to any one of claims 2 to 10, in which the carrier body at least in the region of the thread generating element has a cylindrical shape with respect to the tool axis A, in particular has a cylindrical neck, and / or in which the carrier body at least partially consists of a Steel, especially high-strength steel, is made.

12. The method as claimed in claim 1, in which the tool has thread generating regions formed monolithically on a base body through which the tool axis extends.

13. The method according to claim 12, in which in the base body, which in particular has a cylindrical basic shape, several, in particular five, successive thread teeth (Z1 to Z5) by several, for example five, preferably axially to the tool axis. are separated from one another, which are arranged along the circumference around the tool axis and have thread cutting in the direction of the winding and open spaces behind it, a cylindrical outer surface of the base body being formed in particular axially behind the thread generation region formed from the thread teeth.

14. The method according to claim 12 or 13, in which a cylindrical guide area (33) is formed in front of the thread generation area for guiding the tool on the core hole wall in the core hole (36), in particular the guide area to an end face (32) of the base body passes over a bevel on the face and / or there is a central outlet for coolants and / or lubricants on the face.

15. The method according to any one of the preceding claims, in which the or each thread generation area in the axial direction to the tool axis has an axial extension from a range between 0.5 P and 1.5 P of the thread pitch P or in which the to the tool axis axial distance between between the first thread tooth and the last thread tooth of the thread generation area, opposite to the direction of the winding, is selected from a range between 0.5 P and 1.5 P of the thread pitch P.

16. The method according to any one of the preceding claims, in which the thread profile of the thread turn is successively cut and / or formed from the individual thread teeth to the complete thread profile and / or in which the thread action profiles of the individual thread teeth are divided and at the end the result in a complete thread profile.

17. The method according to any one of the preceding claims, in which the material for the thread teeth and / or the or each thread generating area and / or the thread generating elements and / or the carrier body and / or the base body and / or the entire tool, hard metal such as a Hard metal alloy, in particular P steel or K steel or cermet, or cemented hard metal, in particular tungsten carbide, optionally alloyed or mixed with metals or other metal carbides, or titanium nitride or titanium carbide or titanium carbonitride or aluminum oxide, or cutting ceramics, especially polycrystalline boron nitride (PKB), or polycrystalline diamond (PCD) is provided.

18. The method according to any one of the preceding claims, in which a) during the working movement, the speed of the rotary movement of the tool runs through a first plateau over time, at which the speed remains constant at a predetermined maximum speed (nmax) and b) during the braking movement, the actual speed of the rotary movement of the tool in its temporal course runs through a second plateau at which the speed _{remains constant at the same predetermined maximum speed (n max} ), c) the predetermined maximum speed of the rotary movement of the tool is chosen to be at least large enough that a path speed of at least 57 m / min, in particular of at least 85 m / min, is achieved at the thread generation area, which is a corresponds to a maximum speed of at least 3000 rpm, in particular at least 4,500 rpm.

19. The method according to claim 18, in which between the time interval (Dt1) of the first plateau and the time interval (Dt ₃ ) of the second plateau there is an intermediate time interval (Dt ₂ ) in which the speed drops below the maximum speed, where the ratio (Dt ₂ / Dt ₃ ) of the interval length of the intermediate time interval (Dt ₂ ) to the interval length of the time interval (Dt ₃ ) of the second plateau in a range from 0.5 to 2.2, preferably 0.7 to 1.6, lies.

20. The method according to claim 18 or claim 19, in which the maximum speed is already reached at the beginning of the first work phase or the work movement or at the point where the tool enters the workpiece.

21. The method according to any one of the preceding claims, in which a) the tool in the working movement and in the braking movement is driven by a machine drive and between the machine drive and the tool a transmission unit for the rotary movement, in particular a transmission gear unit, with a specified or specifiable transmission ratio is switched (or: coupled), b) the transmission ratio corresponds to the quotient of the speed of the machine drive and the speed of the tool and is a maximum of 1: 3, so that the tool rotates at least three times as fast like the machine drive, c) where in the programming of the machine drive a maximum speed of the rotary movement of the machine drive is programmed which corresponds to the product of the transmission ratio and the specified maximum speed of the rotary movement on the tool.

22. The method according to claim 21, wherein the transmission ratio between 1: 3 and 1: 8 and preferably between 1: 4 and 1: 5 is selected.

23. The method according to any one of the preceding claims, in which during at least a predominant part of the second work phase or during During the entire second work phase, the tool is moved in the same forward direction as in the work movement in the first work phase and / or wherein the braking movement comprises a rotary movement with the same direction of rotation as in the work movement.

24. The method according to any one of the preceding claims, wherein the rotational speed of the rotational movement at the reversal point is zero and / or at which the total or summed up axial advance of the tool during the braking movement is between 0.1 times and 2 times Thread pitch is selected.

25. The method according to any one of the preceding claims, wherein during the braking movement the axial feed movement depending on the angle of rotation of the rotational movement of the tool according to a previously stored unique relationship, in particular a function or a sequence of functions, between the axial advance of the tool and the angle of rotation is controlled and

26. The method according to any one of the preceding claims, in which, during the braking movement, in several successive braking steps, different relationships, in particular functions, are selected or set between the axial advance of the tool and the angle of rotation.

27. The method according to claim 26, in which a linear function of the angle of rotation is selected during several braking steps for the axial penetration depth or the axial feed and / or in which the slope, ie the derivation of the axial penetration depth or the axial feed after the Drehwin - kel, is set constant in each of these braking steps and decreasing in amount from one braking step to a subsequent braking step.

28. The method according to claim 27, in which an NC control for a threading process, for example a G33 path condition, is used for the working movement the thread pitch of the thread is used and in the several braking steps also one, preferably the same, NC control for a thread process, for example a G33 path condition, with the respective constant pitch is used as the thread pitch parameter.

29. The method according to any one of claims 26 to 28, in which, during several braking steps, the axial penetration depth or the axial advance is a particularly cubic spline function of the angle of rotation.

30. The method according to any one of claims 11 to 14, in which the different functions of successive braking steps are set continuously and, in the case of differentiable functions, preferably continuously differentiable.

31. The method according to any one of the preceding claims, in which, in particular during an equalization step, the axial advance during the braking movement is zero in a rotation angle sub-interval and / or takes place in a rotation angle sub-interval in the reverse direction opposite to the forward direction of the working movement .

32. Method according to one of the preceding claims, in which, after the reversal point has been reached, a reversing movement of the tool is initiated, with which the tool is moved out of the workpiece, the reversing movement initially being a first reversing phase with which the threading generation area of the tool is guided back into the thread turn of the generated thread, and then includes a second reversing phase, during which the thread generation area is guided out of the workpiece through the thread turn.

33. The method as claimed in claim 32, in which the reversing movement is carried out with a movement profile that is symmetrical to the working movement and the braking movement, with a reversed direction of rotation and reversed feed.

34. The method according to claim 32 or claim 33, wherein the reversing movement in the first reversing phase of the same absolute value, inverted only in the direction of rotation and advance direction, previously stored unique relationship, in particular a function or a sequence of functions between the axial advance of the tool and the angle of rotation are controlled as in the braking movement during a second work phase, possibly omitting or shortening the equalization step, if any.