Thread forming tool and method for producing a thread

Abstract

Thread forming tool for the chipless production of an internal thread, comprising a shank (20) on which at least one first thread forming tooth (Z) is mounted. 100 ,..., Z n ; Z 200 ,..., Z n ) and a second thread forming tooth (Z 100 ,..., Z n ; Z 200 ,..., Z n ) are provided, wherein the second thread forming tooth (Z) 100 ,..., Z n ; Z 200 ,..., Z n ) relative to a tool longitudinal axis (A) axially to the first thread forming tooth (Z) 100 ,..., Z n ; Z 200 ,..., Z n ) is arranged offset, with between the first thread forming tooth (Z) 100 ,..., Z n ; Z 200 ,..., Z n ) and the second thread forming tooth (Z 100 ,..., Z n ; Z 200 ,..., Z n ) in the axial direction a gap between teeth (Z L ) is provided so that the axial distance between the first thread forming tooth (Z) 100 ,..., Z n ; Z200 ,..., Z n ) and second thread forming tooth (Z 100 ,..., Z n ; Z 200 ,..., Z n ) greater than or equal to twice the thread pitch (P) to be produced, wherein at least two thread-generating areas (60, 70) are provided which are offset from each other in the circumferential direction with respect to a tool longitudinal axis (A) and are arranged around the tool longitudinal axis (a) and wherein groove-generating areas (80, 90) are formed axially upstream of the thread-generating areas (60, 70) through which grooves can be generated in the wall of a workpiece, wherein each thread-generating area (60, 70) is arranged in an axial projection parallel to the tool longitudinal axis behind at least one groove-generating area (80, 90) and has a smaller cross-sectional area in the axial projection than the respective associated groove-generating area (80, 90).

Description

[0001] The invention relates to a thread forming tool for the chipless production of an internal thread, comprising a shank on which at least one first thread forming tooth and a second thread forming tooth are provided, wherein the second thread forming tooth is arranged axially offset from the first thread forming tooth with respect to a longitudinal axis of the tool. The invention further relates to the use of such a thread forming tool in a method for producing a thread.

[0002] From DE 10 2011 001 772 A1, thread forming tools are known whose tool shanks are generally at least approximately cylindrical about their longitudinal axis and / or are received and held at their end facing away from the workpiece in the chuck of a machine tool. The thread forming tool has groove forming areas for producing a groove in a workpiece and a number of thread forming areas for producing a thread, each of which is arranged in an axial projection parallel to the tool axis behind one of the groove forming areas.

[0003] DE 10 2012 105 183 A1 describes thread-forming tools whose slot-forming areas are spirally shaped around a tool axis, with helical thread-forming areas arranged behind the slot-forming areas. The thread-forming areas are also spirally shaped around the tool axis and follow the spiral of the slot-forming areas.

[0004] DE 10 2005 051 174 B4 describes thread forming tools with a first and a second die, the base regions or the apex regions of which are offset in the axial direction. The first die can be spaced axially from the second die by 1 to 50% of the thread pitch; preferably a range of 3 to 20%, and particularly preferably a range of 10%.

[0005] In both thread forming tools described in the prior art, thread production is carried out by first inserting the thread forming tool with its groove forming areas into a core hole in the workpiece and producing grooves in the wall of the core hole until the thread forming tool reaches the required depth. The thread forming areas follow the groove forming areas in such a way that, upon reaching the target depth, the thread can be produced by a partial or complete rotation. This allows the production of grooves and threads with only one tool.

[0006] Based on the aforementioned prior art, the present invention aims to further develop a thread forming tool according to the preamble of claim 1 in an advantageous manner and to provide a method using such a thread forming tool.

[0007] According to the invention, this problem is solved by providing a tooth gap in the axial direction between the first thread forming tooth and the second thread forming tooth on a thread forming tool according to the preamble of claim 1, such that the axial distance between the first thread forming tooth and the second thread forming tooth is greater than or equal to twice the thread pitch to be produced.

[0008] A tooth gap defining an axial distance between the thread forming teeth of at least twice the thread pitch to be produced corresponds to a recess with the dimensions of a complete thread forming tooth. A tooth gap is defined as a gap or distance between the thread forming teeth that is dimensioned such that the axial distance between the thread forming teeth is equal to or greater than that of a complete thread forming tooth. The axial distance is defined as the distance between the thread forming teeth, for example, relative to their tooth tips or reference points of the tooth flanks, along an axis parallel to a tool longitudinal axis.By providing gaps between the thread forming teeth, or in other words, by removing teeth, fewer teeth engage with the workpiece during the thread forming process, thus reducing the maximum torque. This reduces stress on the tool and increases its service life. Furthermore, the reduction in maximum torque allows for larger thread forming teeth, enabling greater thread depths. Another advantage arises from the fact that, in the first phase of the thread forming process, material is pressed into an area of ​​the workpiece that is initially less affected due to the gaps and thus hardens. As the tool continues to rotate, the thread is pressed into this already hardened area of ​​the workpiece in a second phase of the thread forming process. This makes it possible to produce a very strong thread.Furthermore, the omission of individual teeth enables a simple manufacturing method for thread forming tools, as well as the highly accurate production of threads using such thread forming tools.

[0009] According to the invention, at least, preferably exactly, two thread-forming areas are provided, which are offset from each other in the circumferential direction with respect to a tool axis, and are arranged, in particular, spirally or helically around the tool axis. The first thread-forming tooth and the second thread-forming tooth can be arranged on the same thread-forming area, or the first thread-forming tooth and the second thread-forming tooth can be arranged on different thread-forming areas.

[0010] The thread forming areas can be positioned opposite each other along the tool's longitudinal axis, or, depending on their number, arranged around the tool's longitudinal axis. Providing multiple thread forming areas distributes the forces occurring during thread forming across multiple support points. Furthermore, a design with multiple thread forming areas is a prerequisite for using such a thread forming tool in pre-drilled core holes or for use as a combination tool with integrated groove forming areas.

[0011] In a further advantageous embodiment of the invention, a further thread forming tooth is connected to the first thread forming tooth in the axial direction opposite the tooth gap at a distance equal to the thread pitch and / or a further thread forming tooth is connected to the second thread forming tooth in the axial direction opposite the tooth gap at a distance equal to the thread pitch, in particular such that pairs of thread forming teeth are formed, each separated from the other by a tooth gap.

[0012] The formation of thread-forming tooth pairs, each separated by tooth gaps, also has a beneficial effect on the maximum required torque. The form accuracy of the produced thread is very high when using thread-forming tooth pairs. Furthermore, a thread can be produced in fewer than two turns, enabling highly efficient manufacturing.

[0013] In an advantageous embodiment of the invention, at least one first thread forming tooth pair is arranged on a first thread forming area and at least one second thread forming tooth pair is arranged on a second thread forming area, wherein the axial distance between a first thread forming tooth of the first thread forming tooth pair on the first thread forming area and a first thread forming tooth of the second thread forming tooth pair on the second thread forming area is equal to or more than 1.5 times the thread pitch to be produced.

[0014] In such an embodiment of the invention, a thread can be fully formed by the tool performing a rotation of 2 x 180°. Economically advantageous use of the tool is therefore possible, while simultaneously reducing the required torque.

[0015] In an advantageous alternative embodiment of the invention, each thread forming tooth is separated from the thread forming teeth nearest it in the axial direction in the same thread forming area by a tooth gap.

[0016] The use of such a tool design further reduces the maximum required torque compared to a design with multiple thread-forming tooth pairs. The thread-forming tool only needs to be rotated twice around its axis to produce a thread, thus providing a highly efficient tool.

[0017] In a further advantageous embodiment of the invention, the tooth gap is formed by a recess, such that the distance between the first thread forming tooth and the second thread forming tooth is equal to or more than 2.5 times the thread pitch to be produced, or equal to three times the thread pitch to be produced.

[0018] Such thread forming tools can be manufactured easily. At the same time, the stability and fracture resistance of the tool are not compromised.

[0019] In a further advantageous embodiment of the invention, the tooth gap is formed by a recess whose axial length corresponds to the axial extent of a thread forming tooth and twice the axial extent of a tooth root located between two adjacent thread forming teeth.

[0020] In this way, a thread forming tool can be manufactured whose tooth gap corresponds exactly to the dimensions and size of a thread forming tooth. This allows for the simple production of this thread forming tool.

[0021] According to the invention, groove generation areas are formed axially upstream of the thread generation areas, through which grooves can be generated in the wall of a workpiece, in particular in the wall of a core hole in a workpiece, wherein each thread generation area is arranged in an axial projection parallel to the longitudinal axis of the tool behind at least one groove generation area and has a smaller cross-sectional area in the axial projection than the respective associated groove generation area.

[0022] The advantages of the invention are particularly evident when used with tools that have integrated groove-forming areas. With such tools, a groove can be machined into the wall of a core hole in one step, and the thread can be formed in a further step. Depending on the number of thread-forming areas, only a fraction of a revolution or very few revolutions of the tool may be sufficient to form the thread. The design according to the invention advantageously allows for lower maximum torques during thread production.

[0023] In a further advantageous embodiment of the invention, at least one tooth gap is provided axially between at least one thread forming tooth directly adjacent to a groove forming area and the groove forming area, in particular such that the distance between the groove forming area and the thread forming tooth is equal to or more than a, in particular an integer, multiple of the thread pitch to be produced, preferably equal to twice the thread pitch to be produced or equal to three times the thread pitch to be produced.

[0024] The machined groove-forming areas also cut a recess into the workpiece ahead of the thread forming process. This recess has a radial extent that is greater than the radial extent of the thread forming teeth. Since this cutting action is unavoidable, it can be advantageous to select the distance between the groove-forming areas and the thread forming teeth so that the foremost thread forming tooth is fully engaged in the material during the thread forming process. If the distance is too small, the foremost thread forming tooth will emerge into the recess before the thread forming process is complete.

[0025] The problem of the invention is also advantageously solved by using a thread forming tool according to the invention in a thread production process with the following process steps: a) Creating a number n ≥ 1 of helical grooves in a wall of the workpiece circumferentially around a thread axis or creating a wall of the workpiece having a number n ≥ 1 of helical grooves and circumferentially around a thread axis, b) Inserting one thread-forming area of ​​a tool, helical to match the helical grooves, into each of the helical grooves in a helical insertion motion adapted to the helical groove of the corresponding groove, c) Generating a thread in each wall section of the workpiece adjacent to the groove(s) by rotating the tool about the thread axis and simultaneously axially feeding the tool coaxially to the thread axis at an axial feed rate adapted to the rotational speed and the thread pitch, wherein during the rotation and simultaneous axial feed each thread-generating area engages in the corresponding wall section and generates a corresponding part of a thread turn and, after the rotation, projects back into the same groove or a different groove in the wall. d) Moving each thread-generating area of ​​the tool out of the associated groove in a spiraling withdrawal movement adapted to the spiral of the associated spiral groove.

[0026] In particular, in the step according to feature c), the required torque is reduced by the design of the tool according to the invention, which results in energy savings in the described method.

[0027] According to the invention, the method has the following features: a) Each helical groove is essentially produced as a helical groove, preferably on a cylindrical surface or a cone, extending around the thread axis; b) Each thread generation area, when generating the thread, runs substantially helically, preferably on a cylindrical surface or a cone, around the thread axis;

[0028] In an advantageous embodiment, the method has one or more of the following features c) Each groove and each thread-forming area has the same helix both in the direction of rotation around the thread axis or tool axis and in the helix pitch or helix angle, d) the groove helix pitch is chosen to be significantly larger than the thread pitch, generally at least four times as large, in particular at least six times as large, preferably at least eighteen times as large or even at least thirty-six times as large, e) the groove helix angle is selected to be significantly larger than the thread pitch angle, in particular larger than twice and preferably larger than four times, wherein the angles are measured perpendicular to the thread axis or tool axis relative to the cross-sectional plane, f) the groove helix angle is in a range between 2° and 70°, in particular between 5° and 45° and preferably between r and 25°, g) the directions of rotation or turns of the grooves and threads around the thread axis are the same, i.e. both clockwise or both counterclockwise, or opposite, i.e. one clockwise and one counterclockwise.

[0029] In such a process, grooves in particular can be produced in a particularly advantageous manner, i.e. with very low expenditure of axial force and torque.

[0030] In a further advantageous embodiment of the method, at least one of these features is provided: a) at least one, preferably each, groove is produced by machining, in particular with a machining groove-producing tool or groove-producing area of ​​a tool, for example a broaching or planing tool such as a broaching needle or also with a milling cutter, in particular a slot cutter, b) at least one, preferably each, groove is produced without cutting, in particular with a cutting-free groove-producing tool or groove-producing area of ​​a tool moved in the direction of the desired groove, c) The wall of the workpiece and the grooves in the wall are produced together in one machining process step or with one machining tool.

[0031] In such a process, grooves and threads or even core holes, grooves and threads can be produced in a single or very few process step(s), resulting in a very economical process with high throughput.

[0032] In a further advantageous embodiment of the method, when inserted into the associated groove, the thread-generating area projects into the associated groove in a direction radial to the thread axis, maintaining a radial distance to the groove base and preferably also a distance to the groove flanks.

[0033] This simultaneously moves the thread generation area into the engagement zone as the groove is created, allowing the thread to be produced immediately after the groove is formed. This measure also results in a very economical process.

[0034] Furthermore, a method is advantageous if the wall of the workpiece in which the thread is produced is a core hole wall of a core hole, in particular a blind hole or a through hole, in the workpiece.

[0035] A further advantageous embodiment is created when the grooves and the thread are produced with a single tool which, in addition to the at least one helical thread-forming area(s), also has at least one helical groove-forming area, and / or in a single operation, wherein either only the groove-forming area(s) produces the grooves, or the thread-forming area(s) also reworks or reworks the groove(s) produced by the groove-forming area(s).

[0036] This creates a very fast and accurate thread production process.

[0037] In a further embodiment of the method, at least one of the following features is provided: a) The outer profile of only one thread forming tooth of a thread forming tool already determines the final thread profile of the thread section produced by that tooth, b) the thread is produced with at least two axially offset thread sections with different thread profiles, wherein in particular any thread profiles can be combined in any sequence, c) a first thread section has a thread profile with at least partially smaller dimensions or external dimensions, in particular at the thread root and / or on the thread flanks, than a second thread section, d) the first thread section is a front thread section and the second thread section is a rear thread section, wherein the front thread section is located axially or in the feed direction in front of the rear thread section, e) the first, preferably front, thread section has a flattening in the thread root of its thread profile, f) the second, in particular rear, thread section has a thread profile which has a thread root located radially further outwards than the thread profile of the first, preferably front, thread section, g) the diameter of one threaded part section, in particular the first threaded part section or the front threaded part section, is smaller than the diameter of another threaded part section, in particular the second threaded part section or rear threaded part section.

[0038] In this way, it is possible to produce very precise threads and, moreover, to do so in an economically advantageous manner.

[0039] The invention will be further explained below with reference to exemplary embodiments. Reference is also made to the following drawings, each of which is a schematic representation: Fig. 1 a thread forming tool according to the prior art in a side view; Fig. 2 an alternative thread forming tool according to the prior art in a side view; Fig. 3 a section of a thread forming tool according to the prior art engaged in a workpiece; Fig. 4 a thread forming tool according to the invention in a cutaway view in a first embodiment; Fig. 5 a thread forming tool according to the invention in a cutaway view in a second embodiment; Fig. 6 a thread forming tool according to the invention in a cutaway view in a third embodiment;

[0040] Corresponding parts and sizes are in the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. 6 with the same reference numerals.

[0041] Fig. Figure 1 shows a thread forming tool 10 with a shank 20, in which two thread forming areas 60 and 70 are provided in a front section 30, wherein a groove forming area 80 is axially upstream of the thread forming area 60 and a groove forming area 90 is axially upstream of the thread forming area 70 on the end face 110. A rear section 40 has a polygon 50 with which the thread forming tool 10 can be fixed in a clamping device.

[0042] Each groove-forming area 80 and 90 has an axially forward-facing groove cutting edge located on the end face 110. The groove cutting edges are the radially outermost and axially forwardmost areas of the tool 10 in its front section 30, out of all the radially outer areas. The groove-forming areas have radially outward-facing clearance surfaces 80A and 90A as radial boundaries.

[0043] The two thread generation areas 60 and 70 on the combination tool according to Fig. 1 can be designed to be cutting, i.e. producing the thread by machining, or forming, i.e. producing the thread without machining, and have several thread-producing teeth 120 and 130 arranged at the front in the direction of rotation S around the longitudinal axis A of the tool, the outer contour of which is adapted to the shape of the thread profile to be produced.

[0044] Fig. 2 shows an alternative to the one from Fig. 1. A thread forming tool 10, in which the groove forming areas 80, 90 and the thread forming areas 60 and 70 are helically formed. With such a design of the thread forming tool 10, the axial forces required for grooving are reduced.

[0045] In both embodiments, the thread-forming areas 60, 70 project radially further outwards than the outer surfaces 100. The thread-forming areas 60, 70 have thread-forming teeth 120 and 130 arranged around the longitudinal axis A of the tool on a spiral or helix corresponding to the thread to be produced in terms of the thread pitch. The thread-forming teeth 120 and 130 are the radially furthest projecting areas of the thread-forming areas 60, 70.

[0046] Fig. Figure 3 shows a workpiece 140 with a formed internal thread 150. In internal thread forming or thread forming, the workpiece 140 is pre-drilled with a specific pilot hole diameter. Following the pre-drilling process, the thread former forms the internal thread on the inner walls of the pre-drilled hole in a forming or forming step. The contour of the internal thread 150 has thread flanks 160 that correspond to the contour of the thread former. In the case shown, four thread forming teeth Z are present. 100 , Z 101 , Z 102 , Z 103 in engagement with the workpiece. The distance P between the individual thread forming teeth Z 100 , Z 101 , Z 102 , Z 103 The pitch P of the generated thread is determined by the distance between them, i.e., the distance that a screw would travel in exactly one revolution in the finished thread.

[0047] Fig. Figure 4 shows a sectional view of the front section 30 of a thread forming tool 10 according to the invention in a first embodiment. Groove forming areas 80, 90 are arranged on the end face 110 of the thread forming tool 10, which are axially upstream of the thread forming areas 60, 70. The thread forming area 60 has thread forming teeth Z. 100 to Z 113 and these opposite thread forming teeth Z 200 to Z 213 open, in such a way that two thread forming teeth, e.g. Z, are engaged. 100 , Z 101 and Z 200 , Z 201 , forming pairs, whereby the pairs lying on a thread generation area 60, 70, e.g. the pair Z 100 , Z 101 and the pair Z 103 , Z 104 each from each other through a gap Z L are separated. The gap Z L is indicated by the absence of a thread forming tooth, e.g., Z, as indicated by a dashed line. 102 , Z 105 , Z 108or Z 111 formed. The distance between the immediately adjacent thread forming teeth Z 100 , Z 101 and Z 200 , Z 201 The thread pitch P is the distance between the teeth separated by a tooth gap Z. L separate thread forming teeth Z 101 and Z 103 is twice the thread pitch, i.e., 2P.

[0048] The thread forming area 70 opposite the first thread forming area 60 has correspondingly arranged thread forming tooth pairs Z. 200 , Z 201 as well as Z 203 , Z 204 The axial distance between the thread forming tooth Z 100 and the thread forming tooth Z opposite it 200 is, as is the distance between Z 200 and Z 101 , in the illustrated embodiment P / 2, since the thread forming areas 60, 70, on which the thread forming teeth Z are located 100 and Z 200 are arranged as in Fig. As shown in Figure 4, the thread forming teeth are directly opposite each other, or are offset from each other by 180°. It is of course possible, for example, if there are three thread forming areas that are each offset from each other by 60°, to adjust the axial distance between certain thread forming teeth accordingly.

[0049] The thread forming teeth Z, arranged at the front in the axial direction 100 and Z 200 are separated from the respective groove-generating areas 80, 90 by tooth gaps Z L or free spaces 190 and 290 separately. The distance between the foremost thread forming tooth Z 100 , Z 200 and the groove formation area 80, 90 can also be, for example, P / 2, P or 2P. In this embodiment, the thread forming tool 10 requires a rotation or revolution of 3 x 180° to complete a thread. This follows from the fact that the tooth Z 103The first 180° section of the tool rotation produces the thread assigned to itself, while the second 180° section produces the thread of the exposed tooth Z. 202 and on the third 180° section, the thread of the exposed tooth Z 102 In addition to the 3 x 180° rotation, an inward and outward rotation or movement of the thread forming teeth into and out of the groove wall must also be taken into account.

[0050] The tooth arrangement can be represented in tabular form as follows: Table 1 (left column: thread production range 60, right column: thread production range 70): Z 100 Z 200 Z 101 Z201 Z 102 suspended Z 202 suspended Z 103 Z 203 Z 104 Z 204 Z 105 suspended Z 205 suspended Z 106 Z 206 Z 107 Z 207 Z 108 suspended Z 208 suspended Z 109 Z 209 Z 110 Z210 Z 111 suspended Z 211 suspended Z112 Z212 Z113 Z213

[0051] Fig. Figure 5 shows a thread forming tool 10 according to the invention in a sectional view in a second embodiment. In this embodiment, the thread forming teeth Z 100 , Z 102 , Z 104 , Z 106 , Z 108 , Z119 , Z 112 and Z 114 as well as, Z 200 , Z 202 , Z 204 , Z 206 , Z 208 , Z 210 , Z 212 Each tooth is arranged individually, meaning that each thread forming tooth is separated from the adjacent thread forming teeth by a tooth gap Z. 101 , Z 103 , Z 105 , Z 107 , Z 109 , Z 111 and Z 113 as well as Z 201 , Z 203 , Z 205 , Z 207 , Z 209 , Z 211 and Z 213 separated. The thread forming teeth of each thread forming area 60 or 70 are thus separated from each other by tooth gaps with a distance of 2P. The foremost thread forming teeth Z 100 , Z 200 are separated from the axially upstream groove formation areas 80, 90 by tooth gaps or clearance surfaces 200, 210. In this embodiment, the thread forming tool 10 requires, as also in the embodiment according to Fig. 4, a 3 x 180° turn to complete a thread. According to the embodiment shown. Fig. For example, tooth Z requires 4. 102 The first 180° section of the tool rotation produces the thread assigned to itself, while the second 180° section produces the thread of the exposed tooth Z. 201 and on the third 180° section, the thread of the exposed tooth Z 101 .

[0052] The tooth arrangement of the embodiment according to Fig. 5 can be presented in tabular form as follows: Table 2 (left column: thread production range 60, right column: thread production range 70): Z 100 Z 200 Z 101 suspended Z 201 suspended Z 102 Z 202 Z 103 suspended Z 203 suspended Z 104 Z 204 Z 105 suspended Z 205 suspended Z 106 Z 206 Z 107 suspended Z 207 suspended Z 108 Z 208 Z 109 suspended Z 209 suspended Z 110 Z 210 Z 111 suspended Z 211 suspended Z 112 Z 212 Z 113 suspended Z 213 suspended

[0053] Fig. Figure 6 shows a thread forming tool 10 according to the invention in a sectional view in a third embodiment. In this embodiment, the thread forming area 60 has thread forming teeth Z. 100 , Z 101 , Z 103 , Z104 , Z 106 , Z 107 , Z 109 , Z 110 and Z 112 , Z 113 on, in such a way that two thread forming teeth Z each 100 , Z 101 and Z 103 , Z 104 and immediately form pairs, each separated by a tooth gap. The distance between the immediately adjacent thread-forming teeth Z 100 , Z 101 and Z 103 , Z 104 The thread pitch P is always the same. The intended tooth gaps are formed by omitting one tooth at a time, for example Z. 102 , Z 105 , Z 108 and Z 111 The distance between the thread-form teeth separated by the gap or the exposed teeth, e.g. Z 101 and Z 103 is twice the thread pitch, i.e., 2P.

[0054] The thread forming area 70, opposite the first thread forming area 60, has thread forming tooth pairs Z. 201 , Z 202 and Z 204 , Z 205 and immediately. The axial distance between the foremost thread forming tooth Z 100 of the thread forming area 60 and the foremost thread forming tooth Z 201 The thread forming area 70 is 1.5 times the thread pitch P, in the case that the thread forming areas 60, 70 on which the thread forming teeth 120 and 320 are located as in Fig. 6 are located exactly opposite each other. The axial spacing of the rear thread forming teeth is designed accordingly. In this embodiment, the thread forming tool 10 therefore requires 2 x 180° turns to fully form a thread, in addition to the entry and exit turns.

[0055] The tooth arrangement of the embodiment according to Fig. 6 can be presented in tabular form as follows: Table 3 (left column: thread production range 60, right column: thread production range 70): Z 100 Z 200 suspended Z 101 Z 201 Z 102 suspended Z 202 Z 103 Z 203 suspended Z 104 Z 204 Z 105 suspended Z 205 Z 106 Z 206 suspended Z 107 Z 207 Z 108 suspended Z 208 Z 109 Z 209 suspended Z 110 Z 210 Z 111 suspended Z 211 Z 112 Z 212 suspended Z 113 Z 213

[0056] Fig. Figure 7 shows a thread forming tool according to the invention in a sectional view in a fourth embodiment. In this embodiment, the thread forming area has 60 thread forming teeth Z. 100 , Z 101 , Z 104 , Z 105 , Z 108 , Z 109 , Z 112 and Z 113 on, in such a way that two thread forming teeth Z each 100 , Z 101 and Z 104 , Z 108 and immediately form pairs, each separated by a tooth gap. The distance between the immediately adjacent thread-forming teeth Z 100 , Z 101 and Z 104 , Z 108 The thread pitch P is always the same. The intended tooth gaps are formed by omitting two teeth at a time, for example Z 102 , Z103 , Z 106 , Z 107 or Z 110 , Z 111 The distance between the teeth created by the gap or the exposed teeth Z 102 , Z 103 separate thread forming teeth Z 101 and Z 104 is three times the thread pitch, i.e., 3P.

[0057] The thread forming area 70 opposite the first thread forming area 60 has correspondingly arranged thread forming tooth pairs Z. 202 , Z 203 and Z 206 , Z 207 and immediately. The axial distance between the foremost thread forming tooth Z 100 of the thread forming area 60 and the foremost thread forming tooth Z 202 The thread forming area 70 is 2.5 times the thread pitch P, in the case that the thread forming areas 60, 70 on which the thread forming teeth 120 and 320 are located as in Fig. 6 are located exactly opposite each other. The axial spacing of the rear thread forming teeth is designed accordingly. In this embodiment, the thread forming tool requires 10 3 x 180° turns to fully form a thread, in addition to the entry and exit turns.

[0058] The tooth arrangement of the embodiment according to Fig. 7 can be presented in tabular form as follows: Table 4 (left column: thread production range 60, right column: thread production range 70): Z 100 Z 200 suspended Z 101 Z 201 suspended Z 102 suspended Z 202 Z 103 suspended Z 203 Z 104 Z 204 suspended Z 105 Z 205 suspended Z 106 suspended Z 206 Z 107 suspended Z 207 Z 108 Z 208 suspended Z 109 Z 209 suspended Z 110 suspended Z210 Z 111 suspended Z211 Z112 Z 212 suspended Z113 Z 213 suspended

[0059] In all embodiments, the total number Z can of course be n The thread forming teeth may be higher or lower than specified for the respective embodiment, i.e., larger or smaller than Z. 114 or Z 214 . Reference symbol list 10 Thread forming tools 20 shaft 30 front section 40 rear section 50 polygonal 60, 70 thread production areas 80, 90 groove production areas 80A, 90A Open area 100 outdoor area 110 Front Z 100 , Z 101 ,..., Z n Thread forming teeth Z 200 , Z 201 ,..., Z n Thread forming teeth Z L gap between teeth 140 workpieces 150 internal threads 160 thread flanks A tool longitudinal axis P Thread pitch

Claims

[1] Thread forming tool for the chipless production of an internal thread, comprising a shank (20) on which at least one first thread forming tooth (Z) is attached. 100 ,..., Z n ; Z 200 ,..., Z n ) and a second thread forming tooth (Z 100 ,..., Z n ; Z 200 ,..., Z n ) are provided, wherein the second thread forming tooth (Z) 100 ,..., Z n ; Z 200 ,..., Z n ) relative to a tool longitudinal axis (A) axially to the first thread forming tooth (Z) 100 ,..., Z n ; Z 200 ,..., Z n ) is arranged offset, with between the first thread forming tooth (Z) 100 ,..., Z n ; Z 200 ,..., Z n ) and the second thread forming tooth (Z 100 ,..., Z n ; Z 200 ,..., Z n ) in the axial direction a gap between teeth (Z L ) is provided so that the axial distance between the first thread forming tooth (Z) 100 ,..., Z n; Z 200 ,..., Z n ) and second thread forming tooth (Z 100 ,..., Z n ; Z 200 ,..., Z n ) greater than or equal to twice the thread pitch (P) to be produced, wherein at least two thread-generating areas (60, 70) are provided which are offset from each other in the circumferential direction with respect to a tool longitudinal axis (A) and are arranged around the tool longitudinal axis (a) and wherein groove-generating areas (80, 90) are formed axially upstream of the thread-generating areas (60, 70) through which grooves can be generated in the wall of a workpiece, wherein each thread-generating area (60, 70) is arranged in an axial projection parallel to the tool longitudinal axis behind at least one groove-generating area (80, 90) and has a smaller cross-sectional area in the axial projection than the respective associated groove-generating area (80, 90). [2] Thread forming tool according to one of the preceding claims,characterized by , that exactly two thread forming areas (60, 70) are provided which are offset from each other in the circumferential direction with respect to a tool longitudinal axis (A), and are arranged, in particular, spirally or helically, around the tool longitudinal axis (A), wherein the first thread forming tooth (Z 100 ,..., Z n ; Z 200 ,..., Z n ) and the second thread forming tooth (Z 100 ,..., Z n ; Z 200 ,..., Z n ) are arranged on the same thread forming area (60, 70) or wherein the first thread forming tooth (Z 100 ,..., Z n ) and the second thread forming tooth (Z 200 ,..., Z n ) are arranged on different thread production areas (60, 70). [3] Thread forming tool according to one of the preceding claims, characterized by , that the first thread forming tooth (Z) 101 ; Z 201 ) in the axial direction of the tooth gap (Z 102 ; Z 202) opposite another thread forming tooth (Z 100 ,; Z 200 ) with a distance equal to the thread pitch P and / or that it connects to the second thread forming tooth (Z) 103 , Z 203 ) in the axial direction of the tooth gap (Z 102 ; Z 202 ) opposite another thread forming tooth (Z 104 , Z 204 ) with a distance equal to the thread pitch P, in particular such that thread form tooth pairs are formed, each separated by a tooth gap (Z) 102 , Z 202 are separated from each other. [4] Thread forming tool according to claim 3, characterized by , that at least one first thread forming tooth pair (Z 100 , Z 101 ; Z 103 , Z 104 ; Z 106 , Z 107 ; Z 109 , Z 110 ; Z 112 , Z 113 ) on a first thread forming area (60) and at least one second thread forming tooth pair (Z 201 , Z 202 ; Z 204 , Z205 ; Z 207 , Z 208 ; Z 210 , Z 211 ; Z 213 , Z 214 ) is arranged on a second thread forming area (70) and wherein the axial distance between a first thread forming tooth (Z) 100 ; Z 103 ; Z 106 ; Z 109 ; Z 112 ) of the first thread forming tooth pair on the first thread forming area (60) and a first thread forming tooth (Z 201 ; Z 204 ; Z 207 ; Z 210 ; Z 213 ) of the second thread forming tooth pair on the second thread forming area (70) is equal to or more than 1.5 times the thread pitch (P) to be produced. [5] Thread forming tool according to one of claims 1 to 2, characterized by , that each thread forming tooth (Z 100 , Z 102 , Z 104 ,..., Z n ; Z 200 , Z 202 , Z 204 ,..., Z n ) from the thread forming teeth nearest it in the axial direction (Z 100 , Z102 , Z 104 ,..., Z n ; Z 200 , Z 202 , Z 204 ,..., Z n ) of the same thread generation area (60, 70) by a tooth gap (Z 101 , Z 103 , Z 105 ,..., Z n ; Z 201 , Z 203 , Z 205 ,..., Z n ) is separated. [6] Thread forming tool according to one of the preceding claims, characterized by , that the gap between the teeth (Z L ) is formed by a recess, so that the distance between the first thread forming tooth (Z) 100 ,..., Z n ; Z 200 ,..., Z n ) and second thread forming tooth (Z 100 ,..., Z n ; Z 200 ,..., Z n ) is equal to or more than 2.5 times the thread pitch (P) to be produced, or equal to three times the thread pitch (P) to be produced. [7] Thread forming tool according to one of the preceding claims, characterized by , that the gap between the teeth (Z L) is formed by a recess whose axial length corresponds to the axial extent of a thread forming tooth (Z) 100 ,..., Z n ; Z 200 ,..., Z n ) and corresponds to twice the axial extent of a tooth root located between two adjacent thread forming teeth. [8] Thread forming tool according to one of the preceding claims, characterized by , that groove generation areas (80, 90) are formed axially upstream of the thread generation areas (60, 70), through which grooves can be generated in the wall of a core hole in a workpiece. [9] Thread forming tool according to claim 8, characterized by , that axially between at least one thread forming tooth (Z) immediately adjacent to a groove forming area (80, 90) 100 ,..., Z n ; Z 200 ,..., Z n ) and the groove-generating area at least one tooth gap (Z L) is provided, in particular so that the distance between the groove formation area and the thread forming tooth (Z) 100 ,..., Z n ; Z 200 ,..., Z n ) equal to or more than one, in particular integer, multiple of the thread pitch (P) to be produced, preferably equal to two times the thread pitch (P) to be produced or equal to three times the thread pitch (P) to be produced. [10] Method for producing a thread in a workpiece using a thread forming tool according to one of the preceding claims comprising the following method steps: a) Producing a number n ≥ 1 of helical grooves in a wall of the workpiece circumferentially around a thread axis or producing a wall of the workpiece having a number n ≥ 1 of helical grooves and circumferentially around a thread axis, wherein each helical groove is produced substantially as a groove extending helically around the thread axis, b) Inserting one thread-forming area of ​​a tool, helical to match the helical grooves, into each of the helical grooves in a helical insertion motion adapted to the helical groove of the corresponding groove, c) Producing a thread in each wall section of the workpiece adjacent to the groove(s) by rotating the tool about the thread axis and simultaneously axially feeding the tool coaxially to the thread axis at an axial feed rate adapted to the rotational speed and the thread pitch, wherein during the rotation and simultaneous axial feed each thread-producing area engages in the corresponding wall section and produces a corresponding part of a thread turn and, after the rotation, projects back into the same groove or a different groove in the wall, wherein each thread-producing area, when producing the thread, is substantially helical about the thread axis. d) Moving each thread-generating area of ​​the tool out of the associated groove in a spiraling withdrawal movement adapted to the spiral of the associated spiral groove. [11] The method of claim 10 comprising at least one of the following features: a) Each helical groove is essentially produced on a cylindrical surface or a cone extending around the thread axis, b) Each thread generation area, when generating the thread, essentially runs on a cylindrical surface or a cone around the thread axis, c) Each groove and each thread-forming area has the same helix both in the direction of rotation around the thread axis or tool axis and in the helix pitch or helix angle, d) the groove helix pitch is chosen to be significantly larger than the thread pitch, generally at least four times as large, in particular at least six times as large, preferably at least eighteen times as large or even at least thirty-six times as large, e) the groove helix angle is selected to be significantly larger than the thread pitch angle, in particular larger than twice and preferably larger than four times, wherein the angles are measured perpendicular to the thread axis or tool axis relative to the cross-sectional plane, f) the groove helix angle is in a range between 2° and 70°, in particular between 5° and 45° and preferably between r and 25°, g) the directions of rotation or turns of the grooves and threads around the thread axis are the same, i.e. both clockwise or both counterclockwise, or opposite, i.e. one clockwise and one counterclockwise. [12] Method according to any one of claims 10 to 11 comprising at least one or any combination of the following features: a) at least one, preferably each, groove is produced by machining, in particular with a machining groove-producing tool or groove-producing area of ​​a tool, for example a broaching or planing tool such as a broaching needle or also with a milling cutter, in particular a slot cutter, b) at least one, preferably each, groove is produced without cutting, in particular with a cutting-free groove-producing tool or groove-producing area of ​​a tool moved in the direction of the desired groove, c) The wall of the workpiece and the grooves in the wall are produced together in one machining process step or with one machining tool. [13] Method according to one of claims 10 to 12, wherein, when inserted into the associated groove, the thread forming area projects in a direction radial to the thread axis into the associated groove while maintaining a radial distance to the groove base and preferably also a distance to the groove flanks. [14] Method according to any one of claims 10 to 13, wherein the wall of the workpiece in which the thread is produced is a core hole wall of a core hole, in particular a blind hole or a through hole, in the workpiece. [15] A method according to any one of claims 10 to 14, wherein the grooves and the thread are produced with a single tool which, in addition to the at least one helical thread-forming area(s), also has at least one helical groove-forming area, and / or in a single operation, wherein either only the groove-forming area(s) produces the grooves or the thread-forming area(s) also reworks or reworks the groove(s) produced by the groove-forming area(s) or produces them together. [16] Method according to any one of claims 10 to 15 comprising at least one or any combination of the following features: a) The outer profile of only one thread forming tooth of a thread forming tool already determines the final thread profile of the thread section produced by that tooth, b) the thread is produced with at least two axially offset thread sections with different thread profiles, wherein in particular any thread profiles can be combined in any sequence, c) a first thread section has a thread profile with at least partially smaller dimensions or external dimensions, in particular at the thread root and / or on the thread flanks, than a second thread section, d) the first thread section is a front thread section and the second thread section is a rear thread section, wherein the front thread section is located axially or in the feed direction in front of the rear thread section, e) the first, preferably front, thread section has a flattening in the thread root of its thread profile, f) the second, in particular rear, thread section has a thread profile which has a thread root located radially further outwards than the thread profile of the first, preferably front, thread section, g) the diameter of one threaded part section, in particular the first threaded part section or the front threaded part section, is smaller than the diameter of another threaded part section, in particular the second threaded part section or rear threaded part section.

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