DE102014112164A1 - Threading tool with gothic thread profile and method of making such a thread forming tool - Google Patents

Abstract

Thread forming tool (1) for non-cutting production of threads in workpieces, comprising at least one thread-generating region (32, 34) with at least one pressing lug (321, 322), wherein the pressing lug (321, 322) is formed as a thread-forming tooth and a thread profile with opposing tooth flanks (70, 76, 80, 86, 90, 96), in which the tooth flanks are connected to each other over at least one tooth maximum (73, 83, 93), and wherein the thread profile at least partially substantially circular arc or oblique arcuate or arched or obliquely arched or parabolic or obliquely parabolic.

Description

The invention relates to a thread forming tool for the non-cutting production of threads in workpieces and a method for producing a thread forming tool.

For threading or thread machining chipless processes and non-cutting threading tools are known.

Among the non-cutting thread generating tools are the so-called thread rolls (cf. Handbuch der Gewindetechnik und Frastechnik, publisher: EMUGE-FRANKEN, publisher: Publicis Corporate Publishing, publication year: 2004 (ISBN 3-89578-232-7), hereinafter referred to only as the "EMUGE Handbook", chapter 9, pages 299 to 324 ) and, only for external threads, the thread rolling tools (cf. EMUGE Manual, chapter 11, pages 373 to 404 ).

Gewindefurcher are threaded tools with an approximately helical or helical circumferential thread profile, along which a plurality of pressure studs (also referred to as mold teeth, grooves or mold wedges) are arranged by staggered further outwardly projecting and generally rounded polygonal corner regions of an approximately polygonal cross-section Thread formers are formed. When creating the thread, the thread furrow is similar to the tap with axial feed to the tool axis and rotated about its tool axis in a cylindrical core hole in a workpiece moves, the tool axis of the tap is aligned coaxially to the central axis of the core hole. The rotational speed and the axial feed speed are matched to each other according to the thread pitch. The pressure studs of the Gewindefurchers are permanently engaged with the workpiece at the Kernlochwandung and press the thread by plastic deformation in the Kernlochwandung, so that a continuous thread on the Kernlochwandung arises.

The tool shank of the said thread-generating tools is generally executed at least approximately cylindrically about its longitudinal axis and / or received and held with its end facing away from the workpiece in the chuck of a machine tool. The direction of rotation of a thread rolling when creating the thread corresponds to the sense of winding of the thread to be generated. The screwed into the generated internal thread known screws or screw thread comprise complementary to the internal threads through helical external threads.

• a) das Werkzeug ist um eine Werkzeugachse drehbar,
• b) das Werkzeug weist eine Anzahl n ≥ 1 von um die Werkzeugachse gedrallten Nuterzeugungsbereichen zum Erzeugen jeweils einer Nut in dem Werkstück und eine Anzahl m ≥ 1 von um die Werkzeugachse gedrallten, vorzugsweise helikalen, Gewindeerzeugungsbereichen zum Erzeugen des Gewindes in dem Werkstück auf,
• c) der Drall des oder der Nuterzeugungsbereiche und der Drall des oder der Gewindeerzeugungsbereiche sind aneinander angepasst,
• d) jeder der m Gewindeerzeugungsbereiche ist hinter einem der n Nuterzeugungsbereiche dem Drall dieses Nuterzeugungsbereichs folgend angeordnet.

The DE 10 2012 105 183 A1 discloses a tool for producing a thread in a workpiece, having the features:

• a) the tool is rotatable about a tool axis,
• b) the tool has a number n ≥ 1 of groove generating areas around the tool axis for producing one groove in the workpiece and a number m ≥ 1 of thread generating areas twisted about the tool axis, preferably helical, for creating the thread in the workpiece,
• c) the twist of the groove generating area (s) and the twist of the thread generating area (s) are adapted to one another,
• d) each of the m thread generating regions is arranged behind one of the n groove generating regions following the twist of this groove generating region.

In tools known in the art with twisted thread-forming regions, the creation of a favorable shape geometry adapted to the thread to be produced can be problematic for the thread-generating region.

It is an object of the invention to provide a thread forming tool with a favorable shape geometry and a manufacturing method for such a thread forming tool.

This object is achieved with a thread forming tool with the features of claim 1 and with respect to the method with the features of claim 10. Advantageous embodiments and further developments of the method or tool according to the invention will become apparent from the respective dependent claims.

A thread forming tool for non-cutting production of threads in workpieces according to claim 1 comprises at least one thread-generating region with at least one pressing lug, wherein the pressing lug is formed as a thread forming tooth and has a thread profile with opposite tooth flanks, in which the tooth flanks are connected to each other over at least one tooth maximum, and wherein the thread profile is at least partially substantially circular arc or obliquely arcuate or arcuate or obliquely arched or parabolic or obliquely parabolic.

A circular arcuate or oblique arcuate, or arcuate, or oblique arcuate, or parabolic, or oblique parabola thread profile can be made on a thread forming tooth, even if the thread generation region of the thread forming tooth includes, is strongly twisted trained. Due to the strong swirl, or by a superposition of Furchkeilwinkel and clearance angle, resulting in conventional thread profiles on the thread flanks of the forming tooth two different maxima that do not meet on the outer circumference of the tooth, or the tooth tip. A conventional thread profile can therefore not be produced with a single thread profile grinding wheel, since the thread profile grinding wheel is profiled in such a way that the thread core and thread flank are simultaneously imaged. Spitzbogenförmige or oblique pointed-arched or parabolic or oblique parabolic thread profiles can be formed in an additional grinding step to the thread form tooth. Such thread profiles may be substantially rounded in the transitions of the flanks and / or in the region of the tooth tip or have edges or kinks. The flanks can transition tangentially into a curved contour and thus form an edgeless transition or the flanks can have a sharp bend such as an edge or a kink, or mathematically expressed, the flank can not be differentiable at a certain position. As a thread profile should be understood in this sense, in particular the outer contour of the thread form tooth in the tooth cross-section at a certain position or over a certain length of the tooth.

In an advantageous embodiment of the invention, the opposing tooth flanks are formed as a tooth flank having a first flank portion and a second flank portion and tooth flank with a third flank portion and a fourth flank portion, wherein each of the second flank portion and the fourth flank portion are substantially straight or with in Are formed substantially straight profile sections and / or wherein each of the first flank portion and the third flank portion are curved or formed with substantially curved thread profiles, in particular so that the first flank portion and the third flank portion meet at a tooth maximum and / or merge into each other.

Straight flank sections can be made with a conventionally profiled grinding wheel. In addition to the thread tooth in the region of the tooth maximum, so the area of the tooth of the radially outermost protruding outwardly curved profile sections formed so that an acute-arched or obliquely arched or parabolic or obliquely parabolic contour only in the region of the tooth maximum, while the tooth flanks straight stay. As a result, a particularly high strength of the thread form tooth is achieved and the tooth maximum receives a harmonious rounded transition between the flanks.

In an advantageous development of the invention, the first flank section is curved in a circular arc, in particular defined by a first radius, and / or the third flank section is arcuately curved, in particular defined by a second radius, wherein preferably the first radius is different from the second radius or wherein preferably the first radius is equal to the second radius.

By an embodiment with different Radii an obliquely spitzbogenförmiges thread profile of the thread forming tooth is created, whereby at certain loads an increase in the strength of the thread tooth is achieved, whereby higher forming forces can be achieved. At the same Radii a symmetrical ogive-shaped thread forming tooth is created, which can provide high forming forces, especially at lower feed rates.

In a further advantageous embodiment of the invention, the third flank section is arranged in the feed direction in front of the first flank section, in particular wherein the second radius assigned to the third flank section is greater than the first radius assigned to the first flank section, or in particular wherein the second radius assigned to the third flank section is smaller is as the first radius associated with the first edge portion.

In the case of a tooth maximum which is inclined in the feed direction, that is to say in the case of a second radius which is smaller than the first radius, higher forces, for example, can be absorbed by the tooth. In the case of a tooth maximum inclined counter to the feed direction, an undesired deformation of the thread forming tooth can be reduced, so that the accuracy of the thread to be produced is increased.

In a further advantageous embodiment of the invention, the first central point assigned to the first radius for the first flank section lies on the surface of the second flank section and the second central point for the third flank section assigned to the second radius lies on the fourth flank section or the first central point assigned to the first radius for the first flank section lies between the surfaces of the second flank section and the fourth flank section and the second central point for the third flank section assigned to the second radius lies between the surfaces of the second flank section and the fourth flank section.

If the central points lie on the flank sections, this results in a classic pointed arch-shaped thread profile, which is also called "gothic" profile or gothic pointed arch. The load capacity of a form tooth with such thread profile is very high. If the central points lie between the flank sections, a flatter or lower or compressed pointed-arc-shaped thread profile results. The load capacity is also increased here, at the same time the reason of the thread to be generated is flatter.

As an additional advantageous embodiment of the invention, the opposing tooth flanks may be formed as a tooth flank having a first flank portion and a second flank portion and tooth flank with a third flank portion and a fourth flank portion, wherein the first flank portion and the third flank portion meet at least in a tooth maximum and merge into one another and essentially form a section of a parabolic curve or a parabolic arc.

A tooth with a parabolic thread profile has the advantage over an arcuate thread profile that the tooth maximum or the tooth tip is completely rounded, ie has no edge. A parabolic form also allows a very high load of the forming tooth and thus high thread forming forces.

In an advantageous alternative embodiment of the invention, the first tooth flank is a first flank portion and the second flank forms a second flank portion, wherein the first flank portion and the second flank portion are connected to each other via a tooth back, in particular so that the transition from the first flank portion to the tooth back forms a first tooth edge and / or the transition from the second edge portion to the tooth back forms a second tooth edge.

In such an embodiment, the pressure acting on the thread profile during thread forming can be derived very well over the tooth back. As a result, a thread forming tool is provided which has a very long service life. In particular, those points of the thread profile on which the contour is not mathematically differentiable, or in other words on which the contour forms an edge, a kink or a corner, should be regarded as the tooth edge.

In an advantageous embodiment of the invention, the back of the tooth is shaped like a parabola or shaped like a circular arc.

A tooth back with a parabola-section-shaped or circular-arc shape allows a high load capacity of the thread-forming tooth.

In a further advantageous embodiment of the invention, the tooth edges are each located at different distances from the central axis of the tool, so that an obliquely parabolic or obliquely parabola-shaped or obliquely circular arc-shaped tooth back is formed.

By the tooth edges are far away from the central axis of the tool, creates a slanted tooth back. The misalignment allows, for example, a further increase in the load capacity of the thread form tooth. Depending on the machining task, the misalignment can be adjusted in the direction of the feed direction of the tool or counter to this direction.

In a further advantageous embodiment of the invention, the at least one pressing lug on a thread to be generated in the thread pitch and the sense of winding corresponding helix is disposed about the tool axis and / or that the at least one pressing lug has a defined thread pitch.

In such an arrangement, a defined thread with a defined pitch can be formed. In particular, when a plurality of pressure lugs are arranged on the helix, a thread can be produced particularly advantageously.

In a further advantageous embodiment of the invention, at least two threaded generating regions, each with at least one, preferably a plurality, are provided on pressing lugs, wherein the threaded generating regions are designed to be twisted about the tool axis, in particular with a defined helix angle.

In particular with twisted thread-generating regions, the advantages of the invention come into play, since the opposite tooth flanks are not exactly symmetrical due to the twist and thus the curved regions of the thread profile can not be connected to a single radius. With a tooth having a thread profile according to the invention, it is also possible to provide strongly twisted thread-generating regions with favorable rounding.

In a further advantageous embodiment of the invention, the twist angle of the thread-generating region to the thread pitch angle of the spinning stud a ratio of 1: 7 to 1:13, preferably of 1:10.

In a highly twisted thread-generating region is particularly advantageous by the provision of rounding according to the invention, since distortions of the tooth geometry resulting from the twist can be compensated and thread teeth can be produced with favorable geometric properties. A ratio of helix angle of the thread generating portion to thread pitch angle of the spinning lug of 1: 7 to 1:13, preferably 1:10, corresponds to a ratio of φ = 7 Θ to φ = 13 Θ, preferably φ = 10 Θ. Especially with such twisted thread generating areas, a tooth geometry designed according to the invention achieves a very high load capacity and thus very high usable forming forces.

• a) Bereitstellen eines Werkzeugrohlings;
• b) Erzeugen wenigstens eines Gewindeformzahns in einem ersten Schleifprozess, wobei das im ersten Schleifprozess verwendete erste Schleifwerkzeug den Gewindegrund und die geraden Zahnflankenabschnitte erzeugt;
• c) Bearbeiten des wenigstens einen Gewindeformzahns in einem zweiten Schleifprozess, wobei das im zweiten Schleifprozess erzeugte zweite Schleifwerkzeug einen gekrümmt ausgebildeten ersten Flankenabschnitt und einen gekrümmt ausgebildeten dritte Flankenabschnitt, und insbesondere ein Zahnmaximum, erzeugt;

Ein derartiges Herstellungsverfahren ermöglicht die Herstellung eines Gewindeformwerkzeugs mit sehr stark gedrallten Gewindeerzeugungsbereichen, wobei die Zahngeometrie in einem zweiten Schleifschritt in einem Zahnmaximum abgerundet oder gekrümmt hergestellt wird. Dadurch kann ein Gewindeformwerkzeugs mit sehr stark gedrallten Gewindeerzeugungsbereichen bei gleichzeitig vorteilhafter Zahngeometrie bereitgestellt werden.A method for producing a thread forming tool, in particular according to one of the preceding claims, comprising the following steps:

• a) providing a tool blank;
• b) producing at least one thread forming tooth in a first grinding process, wherein the first grinding tool used in the first grinding process produces the thread root and the straight tooth flank portions;
• c) machining the at least one thread forming tooth in a second grinding process, wherein the second grinding tool produced in the second grinding process produces a curved first flank section and a curved flank section, and in particular a tooth maximum;

Such a manufacturing method makes it possible to produce a thread forming tool with very highly twisted thread-generating regions, wherein the tooth geometry is produced rounded or curved in a second grinding step at a tooth maximum. As a result, a thread forming tool can be provided with very highly twisted thread-generating regions with a simultaneously advantageous tooth geometry.

In a further advantageous embodiment, the second grinding tool has a concave, preferably an arcuate or oblique pointed-arch-shaped or parabolic or obliquely parabolic profile.

In particular, by using a concave, preferably arched or obliquely pointed or parabolic or obliquely parabolic profile, a corresponding counter profile or thread profile can be ground to the tooth maximum prepared in a first grinding step. As a result, mold teeth can be created in highly twisted threaded production areas with favorable tooth geometry in a simple manner.

The invention will be explained below with reference to exemplary embodiments. It is also referred to the drawing, in whose

1 a combined tool with two thread-generating regions and upstream groove-producing regions in a perspective view,

2 the tool according to 1 in a perspective side view,

3 a front part of the tool according to 1 and 2 in a longitudinal section,

4 a core hole in a sectional view with a thread to illustrate the various angular relationships;

5A and 5B an inventively designed thread profile of a Drückstollens

6A and 6B an alternative embodiment of an inventively designed thread profile of a Drückstollens

7 a further alternative embodiment of an inventively designed thread profile of a pressure stud
are each shown schematically. Corresponding parts and sizes are in the 1 to 6 provided with the same reference numerals.

The 1 and 2 show in different representations a combined tool 1 according to the invention, wherein in the front section 5 of the tool 1 two forming threaded production areas 32 and 34 still on the front page 6 a groove production area 42 before the thread generation area 32 and a groove generating area 44 before the thread generation area 34 are vorgelagert with swirl. Not shown are thread-forming tools without groove generating area, so pure thread forming tools or Gewindefurcher, which may nevertheless also be formed according to the invention.

Each groove production area 42 and 44 has an axially forwardly directed at the front side 3 located groove cutting on. The groove cutting edges are the regions of the tool which project radially outward most and which are located axially furthest from the radially outward regions 1 in its front section 5 ,

As in 3 is shown, the radius r0 of the groove cutting edge 42A by a differential radius Δr greater than the radius r1 of the first threaded generating portion 321 and as the, in 3 , to the radius r1 same radius r2 of the second threaded generating portion 322 ,

At each groove cutting edge 42A joins laterally in the circumferential direction in the direction of rotation S to the tool axis A front side cutting and a rotation direction S about the tool axis A rear side region.

The front side cutting edge cuts while the tool is being turned to create the thread 1 in the direction of rotation S laterally into the workpiece and is ground accordingly, so that radially inward a rake surface connects to the chip removal. The rear side area, however, is blunt and preferably convex, since it only follows, but does not have to cut.

Axial behind the groove cutting edge 42A closes an open space 42B on, as in 3 shown, from radius r0 to a radius that is smaller than the radius r1 of the first lug 321 , decreases, in particular linear or conical.

Radially inward closes to the Nutschneide 42A a frontal rake surface 42C on, which extends linearly or concavely curved axially to the rear and on when clearing the groove with the Nutschneide 42A spills occur. The rake surface 42C extends axially from a lowest point back to a flat, directed perpendicular to the tool axis A central area, the central opening of a central channel 50 of the tool 1 surrounds, can be supplied via the coolant and / or lubricant.

The two thread generation areas 32 and 34 at the combination tool 1 according to 1 to 3 are formed forming and have several in the direction of rotation S about the tool axis A front threaded tapping teeth or press studs 32A and 34A whose outer cutting edges are adapted to the shape of the thread profile to be produced. Outside closes opposite to the direction of rotation S to the thread teeth 32A and 34A an outer open space 32B respectively. 34B on, which ends at a rear side in the sense of rotation S.

The from the front 3 seen first two thread-generating portions of the thread-generating portion 32 each with a lug are in 3 With 321 and 322 designated.

The press studs 32A and 34A are the radially outermost regions of the threaded generating regions 32 and 34 , The groove production areas 42 and 44 stand out how well in 3 to recognize radially even further outward than the thread-generating regions 32 and 34 ,

The groove cutting 42A and 44A lie in the in 1 to 3 illustrated embodiment in a common plane which is directed perpendicular to the tool axis A, so are axially at the same height. As a result, the blade edges or open spaces behind are the groove generating areas 42 and 44 corresponding to the pitch P different lengths. In one embodiment, not shown, the groove cutting 42A but also be offset by the pitch P axially offset from each other to an equal axial length of the groove generating areas 42 and 44 to enable.

In a threading tool 1 according to 1 to 3 For example, the thread forming areas only work the thread by a small rotation between one of the groove generating area 42 generated groove and the next, from the groove generating area 44 produced groove, wherein individual thread sections which form parts of the helix of the thread and are interrupted by the grooves or separated from each other, are generated. Each thread forming region and each thread forming tooth or wedge therein thus produces an associated custom thread portion which, when rotated, passes through and is created only once until the next groove and only from that thread forming region and its thread forming wedge. Upon rotation of each thread-generating region to the next-but-one groove, the thread section between two grooves of only two consecutive thread-forming regions and their thread-forming wedges and generally traversed and incorporated together in succession. Conversely, each thread forming region and each thread forming tooth or wedge machined therein the workpiece surface in two successive individual thread sections, one between the first groove for i = 1 with 1 ≤ i ≤ n and the next groove with i = 2 and one between the next Groove (i = 2) and the next but one groove (i = 3 or again i = 1, if n = 2). In general m further turns to the m-th following groove with natural number m work m consecutive thread forming wedges in the same thread section. However, in the rarest cases, m will be greater than 2 or a maximum of 3, but m = 1 is always enough.

The outer profile of only one thread forming wedge (or at most m thread forming wedges) thus already determines the final thread profile of the thread section produced by this tooth or wedge.

Thus, according to the invention, the thread of individual thread sections with virtually any predetermined thread profiles be assembled, wherein the thread profile of each thread section alone or independently of the other thread sections by the outer profile of the associated with the rotation of the thread section threaded forming wedge is shown or generated as complementary thereto.

4 shows an example of a producible with a tool according to the invention thread in a through hole as a core hole 20 with already pulled out threaded generating tool 1 , The thread 36 is completely in the wall portions of the core hole wall 21 of the core hole 20 generated and only in the area of the grooves 22 and 24 interrupted. The center axis M of the core hole 20 is now the thread axis of the thread created with the (interrupted) thread 36 ,

In 4 is also the thread pitch P and the thread pitch angle Φ (relative to the cross-sectional plane perpendicular to the central axis M) of the thread 36 drawn as well as for comparison, the Nutdrallsteigung PN, of which the half PN / 2 is shown, and the Nutdrallwinkel (compared to the cross-sectional plane perpendicular to the central axis M) of the so far visible twisted groove 24 , The groove helix angle corresponds to the helix angle Θ of the thread generating regions or regions 32 . 34 ,

The helix of the grooves is generally chosen to be significantly wider and steeper than the helix of the thread. This means that the thread pitch P, in particular the distance or the pitch of two thread teeth of the thread-generating regions 32 and 34 of the tool 1 corresponds, significantly smaller than the Nutdrallsteigung PN, preferably the slope, or the helix angle Θ the twisted threaded generating regions 32 and 34 of the tool 3 is selected, in general PN> 4 P, in particular PN> 6 P, preferably PN> 18 P, wherein also PN> 36 P may be selected, and / or the thread pitch angle φ of the thread 36 , corresponding to the angle of a thread tooth lying on the thread line to the next on the thread line thread tooth, measured to the central axis M and tool axis A, is significantly greater than the Nutdrallwinkel, in particular the helix angle Θ the twisted thread-generating regions 32 and 34 of the tool 1 corresponds and also to the central axis M or tool axis A is measured, in particular φ> 2 Θ, preferably φ> 4 Θ. The thread pitch angle φ of the thread 36 corresponds to the thread pitch angle φ of the thread-producing press studs 321 . 322 and is therefore used synonymously.

5A shows a thread profile according to the invention designed a Druckstollens 321 in a 3 corresponding detail view. The punching lug 321 or thread tooth or wedge has tooth flanks 70 and 76 which are arranged at an angle of 60 ° to each other, which corresponds to an ISO metric thread. The neighboring press tunnel 322 is from the press tunnel 321 through a tooth base 71 separated. The tooth flank 70 has a first flank section 72 on that into a second flank section 74 passes. The second flank section 74 is straight in profile, ie forms in the longitudinal extent of the pressure stud 321 in the direction of the sense of rotation S a substantially flat surface. Accordingly, the tooth flank 76 a third flank section 75 and a fourth flank section 77 on, wherein the fourth flank section 77 forms a substantially flat surface.

5A and 5B in synopsis illustrate the shape of the first and third flank sections 72 . 75 , The profile lines of the first and third flank sections 72 . 75 each form a defined curve and meet at a tooth or wedge maximum 73 , 5B shows a corresponding construction example in which the flank sections 72 . 75 each with a radius R1, or R2 are rounded, wherein the flank sections 72 . 75 each form a circular arc with radius R1, or R2, the centers M1, and M2 on the second flank section 74 , or on the fourth flank section 77 lies. Second flank section 74 and fourth flank section 77 meet at the intersection of the respective circular arcs at the tooth maximum 73 , As a result, the thread profile of the tooth has the shape of a "Gothic" bow.

6A and 6B show an alternative embodiment of an inventively designed thread profile of a Drückstollens 321 across from 5A and 5B , Also in this embodiment, the pressure lug 321 opposite tooth flanks 80 . 86 on. The tooth flanks 80 . 86 include first and third flank sections 82 . 85 that are rounded or curved. Also the flank sections 82 . 85 are rounded with a radius R3 or R4. The flank sections 82 . 85 form in each case a circular arc with radius R3, or form R4, wherein the centers M3, or M4, unlike in the embodiment according to 5A and 5B , not on the second flank section 84 , or on the fourth flank section 87 lies, but between the tooth flanks 80 . 86 is arranged. In this way, the slope or steepness of the second or fourth flank section decreases 84 . 87 to a greater extent than in the embodiment according to 6A and 6B the case is. The flank sections 82 . 85 meet at the intersection of the circular arcs and thus form the tooth maximum 83 , The thread profile of the tooth thus forms a flat or depressed "Gothic" arch.

7 shows a further alternative embodiment of an inventively designed thread profile of a Drückstollens 321 , The punching lug 321 also has opposite tooth flanks in this embodiment 90 . 96 on. The first tooth flank 90 forms a first flank section 94 and the second tooth flank 96 a second flank section 97 out. The thread profile of the spinning lug is further designed such that the first flank section 94 and second flank section 97 over a tooth back 93 are interconnected in such a way that the transition from the first flank section 94 to the back of the tooth 93 a first tooth edge 92 forms and the transition from second flank section 97 to the back of the tooth 93 a second tooth edge 95 ausformt. In other words, the thread profile at these points in each case a kink or, mathematically expressed, is not differentiable at these points.

The back of the tooth 93 is parabolic section shaped, but it is also possible the back of the teeth 93 form as a circular arc section. Likewise it is possible the tooth edges 92 . 95 each with different distances from the central axis A of the tool form, so that an obliquely parabolic, or obliquely parabola-shaped or obliquely circular arc-shaped tooth back 93 is formed.

Preferred materials for workpieces to be machined with a tool according to the invention are metals, in particular aluminum alloys and magnesium alloys, and other light metals, but the invention is not limited to these materials. Furthermore come as workpieces both thick-walled or massive workpieces and thin-walled components or sheets, especially of steel or other materials into consideration.

LIST OF REFERENCE NUMBERS

1

Thread-producing tool

2

shaft

3

front

4

polyhedron

5

front section

6

rear section

32, 34

Thread-producing area

32A, 34A

Tapping tooth

32B, 34B

open space

33, 35

outer surface

42

Nuterzeugungsbereich

42A

Nutschneide

42B

open space

42C

clamping surface

50

channel

70, 76, 80, 86

tooth flanks

71, 81

tooth root

72, 82

first flank section

73, 83

maximum tooth

74, 84

second flank section

75, 85

third flank section

77, 87

fourth flank section

321, 322

Thread-producing subregion

90, 96

tooth flanks

91

tooth root

92

first tooth edge

93

tooth back

95

second tooth edge

94

first flank section

97

second flank section

A

tool axis

P

Thread

S

rotation

r

radius

r0, r1, r2

radius

.delta..sub.R

radial distance

M

central axis

M1, M2, M3, M4

Central points

R1, R2, R3, R4

radii routes

VR

feed direction

Φ

Lead angle

Θ

angle of twist

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012105183 A1 [0006]

Cited non-patent literature

• Handbuch der Gewindetechnik und Frastechnik, publisher: EMUGE-FRANKEN, publisher: Publicis Corporate Publishing, publication year: 2004 (ISBN 3-89578-232-7), hereinafter referred to only as the "EMUGE Handbook", chapter 9, pages 299 to 324 [0003]
• EMUGE Manual, Chapter 11, pages 373 to 404 [0003]

Claims (14)

Thread forming tool ( 1 ) for non-cutting production of threads in workpieces, comprising at least one thread-generating region ( 32 . 34 ) with at least one pressing lug ( 321 . 322 ), whereby the pressure lug ( 321 . 322 ) is designed as a thread-forming tooth and a thread profile with opposing tooth flanks ( 70 . 76 . 80 . 86 . 90 . 96 ), in which the tooth flanks over at least one tooth maximum ( 73 . 83 . 93 ) are connected to each other, and wherein the thread profile is formed at least partially substantially circular arc or oblique arcuate or arcuate or obliquely arched or parabolic or obliquely parabolic. Thread forming tool ( 1 ) according to claim 1, characterized in that the opposing tooth flanks ( 70 . 76 . 80 . 86 ) as tooth flank ( 70 . 80 ) with a first flank section ( 72 ) and a second flank section ( 74 ) and as a tooth flank ( 76 . 86 ) with a third flank section ( 75 ) and a fourth flank section ( 77 ) are formed, wherein in each case the second flank section ( 74 ) and the fourth flank section ( 77 ) are substantially straight and / or wherein in each case the first flank section ( 72 ) and the third flank section ( 75 ) are formed substantially curved, in particular so that the first flank section ( 72 ) and the third flank section ( 75 ) in a tooth maximum ( 73 ) and / or merge into each other. Thread forming tool ( 1 ) according to claim 2, characterized in that the first flank section ( 72 ) is curved in a circular arc, in particular defined by a first radius (R1), and / or the third flank portion ( 75 ) is arcuately curved, in particular defined by a second radius (R2), wherein preferably the first radius (R1) is different from the second radius (R2) or preferably wherein the first radius (R1) is equal to the second radius (R2). Thread forming tool ( 1 ) According to claim 3, characterized in that the third cross section ( 75 ) in the feed direction (VR) before the first flank section (FIG. 72 ) is arranged, in particular wherein the third flank section ( 75 ) associated second radius (R2) is greater than that of the first edge portion ( 72 ) associated with the first (R1), or in particular wherein the third flank section ( 75 ) associated second radius (R2) is smaller than that of the first edge portion ( 72 ) associated first radius (R1). Thread forming tool ( 1 ) According to one of claims 3 or 4, characterized in that the (first radius R1) (associated with first central point (M1) for the first edge portion 72 ) on the surface of the second flank section ( 74 ) and the second central point (M2) assigned to the second radius (R2) for the third flank section (FIG. 75 ) on the fourth flank section ( 77 ) or that of the first radius (R1) associated with the first central point (M1) for the first edge portion ( 72 ) between the surfaces of the second flank section ( 74 ) and the fourth flank section ( 77 ) and the second central point (M2) assigned to the second radius (R2) for the third flank section (FIG. 75 ) between the surfaces of the second flank section ( 74 ) and the fourth flank section ( 77 ) lies. Thread forming tool ( 1 ) according to claim 1, characterized in that the opposing tooth flanks ( 70 . 76 . 80 . 86 ) as tooth flank ( 70 . 80 ) with a first flank section ( 72 ) and a second flank section ( 74 ) and as a tooth flank ( 76 . 86 ) with a third flank section ( 75 ) and a fourth flank section ( 77 ) are formed, wherein the first flank section ( 72 ) and the third flank section ( 75 ) at least in a tooth maximum ( 73 ) and merge into each other, essentially forming a portion of a parabolic curve or a parabola arc. Thread forming tool ( 1 ) according to claim 1, characterized in that the first tooth flank ( 90 ) a first flank section ( 94 ) and the second tooth flank ( 96 ) a second flank section ( 97 ), wherein the first flank section ( 94 ) and the second flank section ( 97 ) over a tooth back ( 93 ), in particular such that the transition from the first flank section ( 94 ) to the back of the tooth ( 93 ) a first tooth edge ( 92 ) and / or the transition from the second flank section ( 97 ) to the back of the tooth ( 93 ) a second tooth edge ( 95 ) trains. Thread forming tool ( 1 ) according to one of claims 1 or 7, characterized in that the tooth back ( 93 ) parabolic-section-shaped or circular-arc-shaped. Thread forming tool ( 1 ) according to one of claims 1, 7 or 8, characterized in that the tooth edges ( 92 . 95 ) are each at different distances from the central axis (A) of the tool, so that an obliquely parabolic or obliquely parabola-shaped or obliquely circular arc-shaped tooth back ( 93 ) is formed. Thread forming tool ( 1 ) according to one of the preceding claims, characterized in that the at least one pressure lug ( 321 . 322 ) on a thread to be generated in the thread pitch (P) and the winding sense corresponding helix about the tool axis (A) is arranged and / or that the at least one pressure lug ( 321 . 322 ) has a defined thread pitch angle (Φ). Thread forming tool ( 1 ) according to one of the preceding claims, characterized in that at least two threaded generating regions ( 32 . 34 ), each with at least one, preferably a plurality, of spinning lugs ( 321 . 322 ), the thread generating areas ( 32 . 34 ) are formed around the tool axis (A) twisted, in particular with a defined helix angle (Θ). Thread forming tool ( 1 ) according to claim 11, characterized in that the helix angle (Θ) of the thread-generating region ( 32 . 34 ) has a ratio of 1: 7 to 1:13, preferably 1:10 to the thread pitch angle (φ) of the Druckstollens. Method for producing a thread forming tool ( 1 ), in particular according to one of the preceding claims, comprising the following steps: a) providing a tool blank; b) producing at least one thread tooth ( 321 . 322 ) in a first grinding process, wherein the first grinding tool used in the first grinding process, the thread root ( 71 . 81 ) and the straight tooth flank sections ( 74 . 77 ) generated; c) machining the at least one thread tooth ( 321 . 322 ) in a second grinding process, wherein the second grinding tool produced in the second grinding process has a curved first flank section (FIG. 72 ) and a curved third flank section ( 75 ), and in particular a tooth maximum ( 73 ), generated; Method for producing a thread forming tool ( 1 ) according to claim 13, characterized in that the second grinding tool has a concave, preferably a circular arc or oblique arcuate or arcuate or oblique arcuate or parabolic or obliquely parabolic, profile.

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