Connecting element having a clearing section, blank for producing said connecting element, and screw connection having said connecting element

Abstract

A connecting element (1) has a shaft (2) with an external thread (3). After a section (7) with completely formed thread turns (8), a clearing region (10') having thread turns (8') of incomplete height and / or at least one clearing region (10) without thread turns (8) is provided. The invention also relates to a blank for producing the connecting element and to a screw connection made of such a connecting element and a nut part.

Description

[0001] Description

[0002] Fastener with broaching section, blank for producing this fastener and screw connection with this fastener

[0003] Technical area

[0004] The invention relates to a connecting element with a broaching section, comprising a shaft provided with threads of an external thread and having a core diameter dl, wherein the shaft has a drive with force application surfaces and a threaded end. The shaft has a section with load-bearing threads and a broaching section with modified threads is arranged at the threaded end. Such connecting elements can be used for cleaning a contaminated or coated internal thread of a nut component of a positive and non-positively locking and detachable screw connection.

[0005] Furthermore, a blank or blank for producing the connecting element and a screw connection comprising such a connecting element and a nut part are the subject of the invention.

[0006] State of the art

[0007] Thread-broaching screws differ from thread-forming screws in that with thread-broaching screws no thread is created in the nut component, whereas with thread-forming screws a thread is created in the initially unthreaded nut component. Especially when the thread to be produced is a standard thread, the standard-compliant nut thread is always larger than the corresponding standard-compliant screw thread and the thread-forming screw used to produce the nut thread is therefore oversized compared to the standard-compliant screw. This oversize of the standard-compliant screw thread affects both the core diameter and the outer diameter of the screw and is roughly based on the respective dimension of the standard-compliant nut thread.

[0008] In contrast, a thread-clearing screw clears an existing nut thread in the nut component without enlarging the nut thread. The screw geometry of the thread-clearing screw therefore comprises a shank provided with thread turns of an external thread with a core diameter dl that corresponds to the core diameter of the respective standard thread.

[0009] DE 1 802 933 U discloses a head screw whose screw shank is fully formed in an upper cylindrical section and, towards the screw tip, is designed as an end piece in the shape of a truncated cone and provided with notches with sharp-edged edges. The notches have an approximately rectangular or square cross-section and are milled from the screw tip and are inclined to the screw axis. Due to the manufacturing process, the edges protrude beyond the outer surface of the truncated cone. The threads are flattened in the end piece by conical turning.

[0010] This type of screw avoids the need for taps to clear threaded holes, i.e., nut components with internal threads that are coated with paint, and simultaneously prevents the formation of a double thread. The sharp edges scrape off the paint at the top edge when the screw is screwed into the nut component. This paint can be absorbed into the notches, allowing the screw to be screwed in unhindered.

[0011] From DE 1 841 667 U a screw and a nut with a self-cleaning thread are known, in which one or more thread turns are interrupted by one or more grooves from below parallel or diagonally to the screw shaft and form thread turns ends, by means of which contaminants such as rust, paint and resin are cut out of the thread turns of the mating thread and removed via the groove.

[0012] No special measures are disclosed for screwing in the screw or nut.

[0013] DD 274 259 A1 discloses a thread-cleaning fastener. Its thread-cleaning tip is slightly tapered to aid screwing, and one or more slots are cut centrally or eccentrically across a threaded shaft within a front face. The slot thus extends from one point on the circumference through the shaft to another point on the circumference. The slot width should correspond to the thread pitch, and the slot depth should correspond to a maximum of three times the thread pitch.

[0014] Based on the known state of the art, a screw is to be provided which is easy to manufacture, enables good removal of residues such as paint, welding spatter and blasting material in an internal thread of a nut component and at the same time enables easy assembly and prevents malfunctions in a machine-supported or automated screwing process.

[0015] Disclosure of the invention

[0016] A connecting element according to the invention with a broaching section has a shaft provided with an external thread and having a nominal diameter dn and a core diameter dl, wherein the shaft has a threaded end and a section with supporting threads and wherein the broaching section is arranged towards the threaded end and has modified threads.

[0017] The broaching section has at least one broaching groove arranged along the shaft, wherein the at least one broaching groove is free of threads and thread regions adjoining the broaching groove free of threads have a reduced height compared to the height of the supporting threads. The at least one broaching groove ends below the core diameter dl in the shaft at a diameter dy2 which is in the range from 0.75 to 0.99 of the core diameter dl, preferably in the range from 0.90 to 0.98.

[0018] The maximum depth or the diameter dy2 as the minimum diameter can ensure sufficient strength in the reaming area and in particular prevent breakage in the reaming area.

[0019] A further subject of the invention is a connecting element with a broaching section, which has a shaft provided with an external thread and having a nominal diameter dn and a core diameter dl, wherein the shaft has a threaded end and a section with supporting threads and wherein the broaching section is arranged towards the threaded end and has modified threads.

[0020] The broaching section has at least one broaching groove arranged along the shaft, wherein the threads in the region of the at least one broaching groove have a reduced height compared to the height of the supporting threads.

[0021] To achieve sufficient depth, the reaming groove can be smaller than the flank diameter d2 of the external thread, and the reaming groove can end at a diameter dyl that is at most as large as the core diameter dl. A fastener according to these two inventions enables effective removal of residues such as paint, welding spatter, and blasting material in an internal thread of a nut component, and it is easy to manufacture.

[0022] According to a further development, the thread turns or the thread turn regions having a reduced height can have an incompletely formed thread with an incompletely formed thread profile tip created by thread rolling.

[0023] A thread formed in this way is also referred to as underfilled. With this design of the threads with a reduced height or the thread sections adjoining the broaching groove, the thread profile crest is only fully formed outside the broaching area, i.e., the height of the load-bearing threads is only reached outside the broaching area. It has been shown that the desired effect can be achieved.

[0024] This enables cost-effective production of the connecting element with a broaching groove by thread rolling a blank with a groove in a blank shank.

[0025] The broaching groove can extend longitudinally over several thread turns, preferably over a range of 2 to 4 thread turns.

[0026] Furthermore, the at least one reaming groove can have a run-out area into the supporting threads on the side facing away from the thread end in the longitudinal direction. This run-out area can be rounded or straight.

[0027] If the broaching groove is free of threads, the run-out area can extend from below the core diameter dl to the core diameter dl. According to a further development, the broaching groove can be arranged parallel to a longitudinal axis of the shaft. This can simplify the production of the blank for thread rolling of the external thread.

[0028] According to a further development, a threadless pin can be provided in front of the reaming section toward the thread end, wherein the pin has a cross-section dz smaller than the core diameter dl. The pin can, in particular, be cylindrical.

[0029] This pin acts as a shoulder tip and enables insertion into a nut component. After insertion, it also guides and thus supports the fastener in the nut component. This enables easy assembly and can prevent malfunctions in a machine-assisted or automated screwing process.

[0030] The diameter dz of the stud can range from 0.75 to 0.98 times the core diameter dl. This applies particularly to a metric thread according to DIN 13.

[0031] To simplify manufacturing, the at least one reaming groove ending below the core diameter dl in the shank at a diameter dy2 can have a maximum depth of the diameter dz of the stud. This diameter dz is therefore not undercut.

[0032] In particular, the pin can be arranged centrally in order to reduce the risk of jamming of the external thread in the nut component.

[0033] The pin can have a length L of 0.2 to 0.45 times the nominal diameter dn, in particular 0.35 times. It has been shown that a certain length is necessary to achieve the assembly advantages, and that too short a length does not provide any significant assembly advantage. A much greater length, on the other hand, offers no further advantage.

[0034] The external thread can be designed for a positive and non-positive as well as detachable connection with a nut component having a corresponding internal thread. For this purpose, the external thread and the internal thread correspond according to the rules of a standard for screw connections, such as metric ISO thread Din 13 or metric ISO fine thread Din 13, US inch threads such as coarse thread UNG ANS I / ASME Bl . l, fine thread UNF ANS I Bl . 1, extra fine thread UNEF ANS I / ASME Bl . l, British inch threads such as BSW and BSF.

[0035] The external thread can also be a thread with asymmetrical threads, such as that known from DE 10 20105 222 889 B4.

[0036] The broaching area can be manufactured without cutting and be free of machining marks caused by cutting tools.

[0037] The connecting element can be produced by rolling a blank between rolling dies to produce the external thread and the at least one broaching area, wherein the blank has at least one free space along a blank shaft.

[0038] This method of production is cost-effective. The blank itself can be manufactured by pressing or, significantly more complex, by machining. The groove can be arranged parallel to a longitudinal axis of the blank shaft.

[0039] The reaming section can have a transition region extending over a length of at least one thread turn towards the pin, wherein the diameter of the transition region decreases from the core diameter dl with at least one partially formed thread turn to a diameter ds. The height of the thread turn also decreases, in particular until the thread turn disappears. If a pin is provided, the cross-section of the transition region can be reduced to the diameter dz of the pin.

[0040] This transition area, which can be conical, is advantageous when producing the thread by rolling and facilitates the engagement of the thread into a corresponding mating thread or the penetration of the thread into a threadless nut component.

[0041] The broaching groove can be concave in the groove base and in the groove walls and, in particular, have a groove radius RI of 0.15 - 0.2 of a nominal diameter dn of the external thread. The smaller the transition radius R2, the shorter the area with the incompletely formed thread.

[0042] The proportion of reaming grooves in the thread pitches can range between 15% and 50% across the circumference. This allows for sufficient thread load-bearing capacity and sufficient escape for deformed or removed material.

[0043] Three broaching grooves can be arranged at an angle of 120° around the circumference. This allows for good rolling during thread production.

[0044] A further subject of the invention is a screw connection which comprises a connecting element according to the invention and a nut component with an internal thread for receiving the connecting element.

[0045] In such a screw connection, the internal thread can be contaminated and a reliable and cost-effective connection can nevertheless be produced. Yet another object of the invention is a blank for the production of a connecting element as described above, wherein the connecting element can be produced with an external thread having thread turns with a nominal diameter dn and with a core diameter dl by thread rolling of the blank. The blank has a shank with a first shank section with a diameter df for the external thread to be produced.

[0046] In the first shaft section, at least one free space is arranged along the shaft towards a blank end.

[0047] Such a blank can be formed by thread rolling without cutting, so that a connecting element with an external thread is created.

[0048] The diameter df generally corresponds approximately to the diameter d2 of the thread flanks of the external thread to be produced. This diameter df is also referred to as the pre-rolling dimension.

[0049] Several clearances can be spaced apart from one another around the circumference. Three clearances can be arranged at an angle of 120° around the circumference. The quasi-rotationally symmetrical arrangement reduces the notch effect in the pressing tool and, when threads are produced by thread rolling, results in good rolling behavior.

[0050] The proportion of open space across the circumference can be between 15% and 50%.

[0051] The at least one free space can be arranged parallel to a longitudinal axis of the shank. This enables cost-effective production of the connecting element with a broaching groove by pressing a blank with a groove in a blank shank and subsequent thread rolling. In addition, the at least one free space can be designed as a groove and the groove can have a groove radius RI in the groove base and in the groove walls of 0.15 - 0.2 times a nominal diameter dn of the external thread to be produced and a transition radius R2 of the groove walls into a jacket surface of the shank can be smaller than the groove radius RI, but at least 0.2 times RI. Rounded transitions increase the service life of the tool used to produce the groove of the free space.

[0052] In particular, the transition radius R2 can be a maximum of half the groove radius RI and, further restricting the transition radius R2, a maximum of one-third of the groove radius RI. The steepness of the transition area influences the behavior of the subsequent reaming area in the thread, and the smaller the transition radius R2, the shorter the area with an incompletely formed thread.

[0053] The at least one free space can extend over several threads of the external thread to be produced from this blank, preferably over a range of 2 to 5 threads.

[0054] The at least one free space can have a run-out area extending over several thread turns, preferably over a range of 1 to 3 thread turns.

[0055] The depth of the at least one free space can be determined such that the diameter dy2 of the at least one free space ends below a core diameter dl of the external thread to be produced from this blank in the shaft.

[0056] This results in at least a portion of the at least one reaming area resulting from the at least one clearance being free of thread turns after the external thread has been produced by thread rolling. The diameter dy2 of the at least one clearance can, in particular, be in the range of 0.75 to 0.99 of the core diameter dl.

[0057] If the at least one free space ends at a depth on a diameter dyl in the area of ​​the diameter of the blank shaft df and the core diameter dl, this leads to incompletely formed threads in at least one broaching area, since the threads are underfilled.

[0058] The blank may have a shank section toward the end of the blank that tapers conically to a diameter dx smaller than the core diameter dl of the external thread to be produced. This shank section serves as the entry area during thread rolling.

[0059] A pin with a diameter dz can be arranged at the end of the blank. The diameter dz of the pin is smaller than the core diameter dl of the external thread to be produced from this blank. This dimensioning makes it possible for the pin to be machined without additional machining during thread rolling. The pin can be cylindrical.

[0060] For a metric thread according to DIN 13, the diameter dz of the pin can be in a range from 0.68 to 0.89 times the diameter df of the blank shank, preferably in the range from 0.8 to 0.89.

[0061] The core diameter dl for metric threads according to DIN 13 is approximately 0.9 times the pitch diameter d2, depending on the respective nominal diameter dn of the thread, i.e. taking into account the conditions in the finished external thread from 0.75 to 0.98 times the core diameter dl, the above-mentioned range results.

[0062] Other thread standards may have different ratios regarding the pitch height to the core diameter, and thus regarding the pitch diameter and the core diameter. In this case, the corresponding ratio between the pitch diameter and the core diameter must be considered for the ratio of the pin diameter to the blank shank diameter.

[0063] A connecting element according to the invention can be produced from such a blank by rolling a thread.

[0064] According to a further development, the connecting element can have a head on the shaft with a drive having force application surfaces, wherein the head has a larger diameter than the shaft. On an underside of the head facing the shaft, a projection can be formed that projects beyond the underside and is arranged at a constant distance r around the shaft in the circumferential direction.

[0065] When the fastener is screwed in, the projection can come into contact with a surface of the workpiece with the nut thread before the rest of the underside comes into contact. Any electrically insulating coating on the workpiece with the nut thread can be penetrated by the projection, thereby establishing electrically conductive contact between the fastener and the workpiece. For this purpose, both the workpiece with the nut thread and the fastener are made of an electrically conductive material, such as metal.

[0066] According to a further development, the projection can have areas of reduced height and / or be interrupted.

[0067] The projection may have at least one cutting edge.

[0068] Such a cutting edge can be formed on the end of the projection facing away from the underside, so that the cutting edge penetrates any coating that may be present more easily when the connecting element is screwed in.

[0069] The projection may have areas with an interrupted cutting edge. This makes it possible to modify the effect of the cutting edge, for example, to provide circumferential broaching grooves so that the cutting edge acts not only in the axial direction but also in the circumferential direction when screwing in the fastener.

[0070] Advantageously, the projection can be tapered, preferably in an angular range of 80°-125°, in particular 105°. An obtuse angle fills the projection during production by forming, thereby protecting the tool. The flank angles of the tapered projection can be different. It has been shown that an inner flank angle can be 45° and an outer flank angle can be 60°.

[0071] Of particular importance for a good cutting effect of the cutting edge on the projection is a small radius at the tip of the cutting edge, which is preferably less than 0.2 mm, in particular 0.12 to 0.08 mm.

[0072] However, a cutting edge can also be formed by a projection in the form of a circular arc rising above the underside, whereby the cutting edge here lies on a radius.

[0073] To improve electrical conductivity, the underside and / or the projection can be at least partially coated with a material with particularly good electrical conductivity compared to the material of the fastener or the workpiece with the nut thread, for example Cu and / or Ni. Zinc, tin, or silver can also be used. The layer thickness varies depending on the material used and is in particular between 5 pm and 25 pm.

[0074] It is also possible to provide the entire fastener with such a coating, whereby a tin-zinc coating applied by a galvanic process is also suitable.

[0075] Another subject of the invention is a blank for producing a connecting element with an external thread with thread turns having a nominal diameter dn and a core diameter dl by thread rolling. The blank has a shaft with a first shaft section having a diameter df for the external thread to be produced, and the shaft has a head with a drive having force application surfaces. The head has a larger diameter than the shaft, and on an underside of the head facing the shaft there is a projection which projects beyond the underside and is arranged at a constant distance around the shaft in the circumferential direction.

[0076] The projection can be designed as described above and in particular have at least one cutting edge.

[0077] From such a blank, a connecting means with a thread can be produced in compliance with the standard dimensions for screwing into a corresponding nut component, which in addition to broaching the thread in the nut component is also able to provide an electrically conductive contact via the head, even if the nut component is painted.

[0078] According to a further development, the blank can have a projection configured as described above. Furthermore, the underside and / or the projection of the blank can be at least partially coated with a material having particularly good electrical conductivity compared to the material of the connecting means or the workpiece with the nut thread, in particular Cu and / or Ni and / or Ag and / or Zn and / or Sn, before the screw thread is produced.

[0079] Yet another object of the invention is a screw connection comprising a connecting element and a nut component, wherein the nut component has an internal thread for receiving the connecting element or wherein the nut component interacts with the connecting element via a thread-forming direct screw connection in such a way that a projection on an underside of a head of the connecting element penetrates at least partially into the nut component.

[0080] Short description of the drawings

[0081] The connecting element according to the invention, the screw connection and the blank are explained using the drawing.

[0082] It shows :

[0083] Fig. 1 shows a connecting element according to the invention in the form of a screw in a side view;

[0084] Fig. 2 shows the screw from Fig. 1 in a perspective view;

[0085] Fig. 3 is a plan view of the screw from Fig. 1 without head, seen from the threaded end;

[0086] Fig. 4 shows the external thread of the screw from Fig. 1 with a reaming area in detail;

[0087] Fig. 5 shows the clearance area from Fig. 3 in detail with the location of sections 1 to 5;

[0088] Fig. 6 shows sections 1 to 5 according to Fig. 5; Fig. 7 shows a blank according to the invention with a free space in a side view;

[0089] Fig. 7A is a section through the blank of Fig. 7 along the line AA;

[0090] Fig. 7B shows a detail of the clearance of the blank from Fig. 7;

[0091] Fig. 7C a longitudinal section through the blank from Fig. 7;

[0092] Fig. 7D is a plan view of the blank of Fig. 7, without head, seen from the tip;

[0093] Fig. 7E an alternative embodiment to Fig. 7C a longitudinal section through the blank from Fig. 7;

[0094] Fig. 8 another blank with several free spaces in a side view;

[0095] Fig. 9A is a schematic representation of a screw connection of a screw according to the invention into a nut part with an internal thread;

[0096] Fig. 9B is a schematic representation of a screw connection of a screw according to the invention into a nut part without an internal thread;

[0097] Fig. 10 shows a further connecting element according to the invention in the form of a screw;

[0098] Fig. 11 shows the screw from Fig. 1 with a cup-shaped cutting edge arranged on a head in a side view;

[0099] Fig. 12A shows an enlarged detail of the ring cutting edge from Fig. 11;

[0100] Fig. 12B shows a coating of the projection in detail;

[0101] Fig. 13A-D show various designs of interruptions in the projection; Fig. 13E shows a view of the underside of the head with a projection interrupted several times around the circumference.

[0102] Embodiment of the invention

[0103] Fig. 1 shows a connecting element with a broaching section in the form of a screw 1, wherein a shaft 2 is provided with an external thread 3 and has a nominal diameter dn and a core diameter dl. The screw 1 has a head 4 with a drive 5 with force application surfaces 6. The shaft 2 has a section 7 with fully formed threads 8 and, towards a thread end 9, a broaching section 10 with modified threads 8'.

[0104] The broaching section 10 has a broaching groove 11 arranged along the shaft 2, which is free of threads and which ends below the core diameter dl in the shaft 2 at a diameter dy2 (Fig. 4). The broaching groove 11, which is free of threads, is followed by thread regions 12 which have a height which is reduced compared to the height of the threads 4. The thread regions 12 which have a reduced height in the region of the broaching groove 11 are underfilled, i.e. are incompletely formed compared to the fully formed threads 8.

[0105] A further object of the invention, which is not expressly shown, differs from the embodiment described in Fig. 1 in that the broaching section 10 has modified threads 8 ' and a broaching groove 11 ' arranged along the shaft 2, the threads 8 ' in the region of the broaching groove 11 ' having a reduced height compared to the height of the supporting threads 8. The broaching groove 11 ' is less than the flank diameter d2 of the external thread 3 in its depth and ends at a diameter dyl which is greater than the core diameter dl.

[0106] The thread turns 8 ' in the area of ​​the broaching groove 11 ' which have a reduced height are underfilled and are therefore incompletely formed compared to the fully formed thread turns 8 .

[0107] The broaching groove 11, 11' shown extends in the longitudinal direction over three thread turns 8' and has, on the side facing away from the thread end 9 in the longitudinal direction, a run-out area 13 into the supporting thread turns 8, so that the core diameter dl is then reached again and the broaching groove 11 is closed.

[0108] In the embodiment of the invention not shown, the incompletely formed threads 8 ' grow to their full height and the broaching groove 11 ' is closed.

[0109] The broaching groove 11, 11' is arranged parallel to a longitudinal axis of the shaft 2, and after the broaching section 10 and after the thread end 9, a thread-free pin 14 is arranged centrally, the diameter dz of which is smaller than the core diameter dl. The broaching groove 11, which ends below the core diameter dl in the shaft 2 at a diameter dy2 (Fig. 4), reaches a depth of at most the diameter dz of the pin. The pin has a length of 0.35 times the nominal diameter dn.

[0110] The external thread 3 is designed for a positive and non-positive as well as detachable connection with a nut component (not shown) having a corresponding internal thread, wherein the external thread and the internal thread correspond to the rules of a standard for screw connections.

[0111] The external thread 3 and the reaming section 10 are produced by rolling a blank between rolling dies, with the blank having a clearance along a blank shank and described below. Due to the non-cutting production, the screw is free of machining marks from cutting tools.

[0112] The broaching section 10 has a transition region 15 extending over a length of one thread pitch toward the thread end 9. The diameter of the transition region 15 decreases from the core diameter dl with at least one partially formed thread pitch to a diameter ds, and the height of the thread pitch decreases until the thread pitch disappears. The thread crest is retained at this thread runout to ensure engagement of the external thread with a nut component. The thread pitch is not underfilled.

[0113] In the perspective view in Fig. 2 of the screw according to Fig. 1, a further broaching groove is provided in the broaching area 10

[0114] 11.1, which is arranged on the circumference of the shaft 2 at a distance of 120°.

[0115] In the top view of the threaded end 9 in Fig. 3, a third reaming groove 11.2 can be seen, with the three reaming grooves 11, 11.1, 11.2 being arranged at an angle of 120° around the circumference. The head 4 has been omitted in this illustration. The proportion of the reaming grooves 11, 11.1,

[0116] 11.2 on the threads seen over the circumference is 33%.

[0117] The pin 14 has a diameter dz, and in the transition area 15, a first thread pitch 16 of the external thread 3 (Fig. 1) is shown, which is interrupted in the area of ​​the reaming grooves 11, 11.1, 11.2. The run-out area 13 is shown in view of the reaming grooves 11, 11.1, 11.2. The reaming groove 11 is concave in the groove base 17 and in the groove walls 18, 19 and has a groove radius RI that is 0.15 - 0.2 of a nominal diameter dn. The groove base 17 lies at a diameter dy2 below the core diameter dl (not shown). Furthermore, at a convex transition of the groove walls 18, 19 into a lateral surface of the shaft 2, there is a transition radius R2 which is smaller than the groove radius RI and is more than 0.2 times the groove radius RI.

[0118] Fig. 4 shows the external thread 3 of the screw 1 from Fig. 1 with the reaming area 10 and the reaming groove 10 as a schematic representation in detail. Starting from the threadless pin 14, a transition area 18 follows, which is conical and has an included cone angle of preferably 60°. Other cone angles are possible.

[0119] In the transition area 15, the broaching groove 10 is already only partially present, since the diameter of the pin is smaller than the core diameter of the external thread 3 and the broaching groove extends below the core diameter, namely to the diameter dy2 (Fig. 3), but not so deep that the diameter dz (Fig. 3) of the pin 14 is reached.

[0120] Fig. 5 shows the broaching area 10 from Fig. 3 in detail, indicating the position of sections 1 to 5 parallel to the longitudinal axis of the screw 1 along the thread section 12 (Fig. 1). Starting from the groove base 17, the thread section 12 extends to the thread crest of the thread 8' in the broaching area 10 and adjacent to it in the run-out area 13 and in the transition area 15 accordingly. In the transition area there is a thread section 12' which is still part of a thread run-out. In Fig. 6, the sectional profile of the thread section 12 along sections 1 to 5 according to Fig. 5 is shown schematically in detail. The thread crest is only fully developed in section 1, and sections 2 to 5 towards the groove base 17 show an increasingly reduced height of the thread, since the thread is increasingly underfilled and has completely disappeared in the groove base 17.Such a course of the thread is possible by producing the external thread by rolling a blank with a clearance as described below.

[0121] This special course of the thread , even with a broaching groove 11 ' that does not extend below the core diameter ( Fig . 10 ) , contributes to the effect of the broaching area and is not achieved with screws with a machined broaching groove .

[0122] Fig. 7 shows a blank 21 according to the invention for producing a connecting element as described above with an arranged free space 22 in a side view. The connecting element is to be produced by thread rolling the blank with an external thread having a nominal diameter dn and a core diameter dl. For this purpose, the blank 21 has a shaft 23 with a first shaft section 24 with a diameter df for the external thread to be produced with a nominal diameter dn and a core diameter dl.

[0123] The free space 22 is arranged parallel to a longitudinal axis of the shaft at one end 25 of the first shaft section 24, followed by a second shaft section 26 which tapers conically to a diameter dx smaller than the core diameter dl of the external thread to be produced. At the end 27 of the second shaft section 26, a pin 28 with a diameter dz is arranged, the diameter dz of the pin 28 being smaller than the core diameter dl of the external thread to be produced from this blank, having a nominal diameter dn. The diameter dz of the pin 28 for the production of a metric thread according to DIN 13 is in a range from 0.68 to 0.9 times the diameter df of the blank shaft 23.

[0124] The free space 22 extends over several threads of the external thread to be produced from this blank and has a run-out area 29 extending over several threads of the external thread to be produced from this blank.

[0125] Fig. 7A shows a section through the blank 21 from Fig. 7 along line AA. The three clearances 22 are spaced apart from each other at an angle of 120° and distributed over the circumference of the shaft 23. The proportion of clearances over the circumference is approximately 33%.

[0126] The free space 22 is formed as a concave groove with a groove radius RI in a groove base 17 and in groove walls 18, 19, which lies in the range of 0.15 - 0.2 times a nominal diameter dn of the external thread to be produced, which, in the case of a metric external thread to be produced, with a conversion factor of approximately 0.9, corresponds to approximately 0.13 - 18 times the shaft diameter df. A convex transition of the groove walls into a lateral surface of the shaft is formed with a transition radius R2 that is smaller than the groove radius RI and more than 0.2 times the groove radius RI.

[0127] The depth of the clearance 22 is set such that the diameter dy2 of the clearance 22 ends below the core diameter dl of the external thread to be produced from this blank 21 in the blank shank 23 with the diameter df, whereby the diameter dy2 is in the range of 0.75 - 0.99 of the core diameter dl. With a ratio of the core diameter dl to the diameter df of the shank 23 which approximately corresponds to a pitch diameter d2 of the external thread to be produced, which for a metric thread is approximately 0.9, the diameter dy2 for the blank 21 is in a range of 0.67 - 0.90 of the diameter df of the shank 23 or the pitch diameter d2.

[0128] For the connecting means in the form of a screw 60 shown in Fig. 10, a broaching section 10' is provided in an external thread 2 with thread turns 8, which broaching section has a broaching groove 11' made up of a plurality of underfilled thread turns 8', the height of which is reduced to no more than the core diameter dl. The broaching groove 11' is not continuous here, but consists of the essentially unconnected valleys of the underfilled thread turns 8'. Because the thread is underfilled in this area, a special contour is created in a thread turn section 12', similar to that in Fig. 6. This screw 60 can have other features of the previously shown and explained screw 1 outside of the broaching section 10', so that a repetition is omitted.

[0129] The depth of the free space 22 of a blank suitable for the production of such a screw 60 is determined such that the diameter dyl of the free space 22 ends above the core diameter dl of the external thread 61 to be produced from this blank 21 in the blank shank 23.

[0130] Fig. 7B shows a detail of the free space of the blank from Fig. 7, wherein the free space 22 on one side partially projects into the conically tapered shaft section 26 and the run-out region 29 tapers in width on the other side, i.e. becomes narrower in the circumferential direction. Fig. 7C shows a longitudinal section through the blank 21 from Fig. 7 and it can be seen that the run-out region 29 is rounded in the groove base 17 and rises from the depth of the free space 22 up to the outer surface of the shaft 23. As in Fig. 7B it can be seen that the free space 22 ends in the transition region 26 in front of the pin 28. The depth of the free space is above the diameter dz of the pin 28.

[0131] Fig. 7D is a plan view of the blank 21 from Fig. 7, without the head, seen from the pin 28, so that the transition region 26 can also be seen. As in the section according to Fig. 7A, the three free spaces 22 are distributed evenly over the circumference in the shaft 23, which has a diameter df. The free spaces 22 end in their depth above the diameter dz of the pin 28 at a diameter dy2.

[0132] Fig. 7E shows an alternative embodiment to Fig. 7C in a longitudinal section, wherein instead of a rounded outlet region 29 a straight outlet region 29' is provided, which lies at an angle α of 10° to 20° to the longitudinal axis.

[0133] Fig. 8 shows a side view of another blank 31 with several clearances 32 in a shaft 33. The clearances 32 are evenly distributed over the circumference of the shaft 33, and the proportion of clearances 32 over the circumference is approximately 50%. This design also features a tenon 34 whose diameter dz is dimensioned such that the clearances 32 do not extend any deeper.

[0134] Fig. 9 is a schematic representation of a screw connection of a screw according to the invention, either into a nut part 40 with an internal thread 41 in an opening 42 or as a direct screw connection into a nut part 50 with an opening 51 without an internal thread. For a screw with a metric M5 thread, the core diameter dl is 4.019 mm and the flank diameter d2 is 4.480 mm. A diameter dy2 of 4.0 mm was selected for the depth of the broaching groove, and a value of 3.7 mm for the diameter dz of the pin. The length of the pin is 1.75 mm.

[0135] For a screw with a metric M8 thread, the core diameter dl is 6.466 mm and the flank diameter d2 is 7.188 mm. A diameter dy2 of 6.0 mm was chosen for the depth of the reaming groove, and the diameter dz of the stud is 5.9 mm. The stud length is 2.8 mm.

[0136] For a screw with a metric M16 thread, the core diameter dl is 13.546 mm and the flank diameter d2 is 14.701 mm. A diameter dy2 of 13.0 mm was chosen for the depth of the reaming groove, and the diameter dz of the stud is 12.9 mm. The stud length is 5.8 mm.

[0137] The screw 1 from Fig. 1, shown in a side view in Fig. 11, has a head 4 with a larger diameter than the shaft 2. On an underside 71 of the head 4 facing the shaft 2, a projection 4.2 is formed which projects beyond the underside and is arranged in the circumferential direction at a constant distance r around the shaft 2. To form a type of ring cutting edge, the projection 4.2 has at least one cutting edge 4.3.

[0138] The projection 4.2 carrying the cup-shaped cutting edge is incorporated as a negative mold into the die used to manufacture the fastener, which fills up when the head is pressed.

[0139] In Fig. 12A, the projection is shown in detail as a partial section of Fig. 11. The projection 4.2 tapers to the cutting edge 4.3 at an angle a of 105°. The flank angles of the tapered projection 4.2 are different: an inner flank angle a1 is 45° and an outer flank angle a2 is 60°. A radius rS at the tip of the cutting edge 4.3 is 0.1 mm.

[0140] In the embodiment according to Figs. 11, 12, the projection 4.2 has no radial interruptions.

[0141] In Fig. 12B it is shown that a surface 4.4 of the projection 4.2 is provided with a coating with a particularly good electrical conductivity, in the present case with Cu and / or Ni, but other processes would also be conceivable, such as tinning.

[0142] Fig. 13A-D illustrate various radial interruptions in the protruding projection 4.2. Fig. 13A shows a shallow notch in the projection 4.2, extending to the underside supporting the projection, providing a chip space for scraped or displaced material.

[0143] Fig. 13B shows a steep notch in the projection 4.2, which extends to the underside supporting the projection.

[0144] Fig. 13C shows a projection 4.2 with several adjacent sawtooth-like notches, which extend to the underside supporting the projection.

[0145] Fig. 13D shows a projection 4.2 with a steep notch and a flat outlet, the notch extending to the underside supporting the projection.

[0146] Fig. 13E shows a view of the underside 4.1 of the head 4 with a projection 4.2 which is interrupted several times over the circumference.

[0147] The height of the ring edge does not depend on the dimension of the

[0148] The choice depends not on the screw, but on the paint thickness. Fasteners with smaller or larger heights can be provided for different paint thicknesses.

Claims

Patent claims 1. Connecting element with a broaching section (10), comprising a shaft (2) having an external thread (3) with a nominal diameter dn and a core diameter dl, wherein the shaft (2) has a threaded end (9) and a section (7) with fully formed threads (8), and wherein the broaching section (10) is arranged towards the threaded end (9) and has modified threads (8'), characterized in that - the broaching section (10) has at least one broaching groove (11), wherein the at least one broaching groove (11) is free of threads (4) and thread regions (12) adjoining the broaching groove (11) free of threads (4) have a reduced height compared to the height of the supporting threads (4), - that the at least one broaching groove (11) is arranged along the shaft (2) and - that the at least one broaching groove (11) ends below the core diameter dl in the shaft (2) at a diameter dy2 which is in the range of 0.75 - 0.99 of the core diameter dl.

2. Connecting element with a broaching section (10'), comprising a shaft (2) having an external thread (3) with a nominal diameter dn and a core diameter dl, wherein the shaft (2) has a threaded end (9) and a section (7) with fully formed threads (8), and wherein the broaching section (10') is arranged towards the threaded end (9) and has modified threads (8'), characterized in that - the broaching section (10') has at least one broaching groove (11'), wherein the threads (8') in the region of the at least one broaching groove (11') has a reduced height compared to the height of the fully formed threads (8), wherein the broaching groove (11') in particular falls below a flank diameter d2 of the external thread (3) and ends at a diameter dyl which is at most as large as the core diameter dl; - and that the at least one broaching groove (11') is arranged along the shaft (2).

3. Connecting element according to claim 1 or 2, characterized in that the thread turns (8') or the thread turn regions (12) having a reduced height have an incompletely formed thread with an incompletely formed thread profile tip produced by thread rolling.

4. Connecting element according to one of claims 1 to 3, characterized in that the at least one broaching groove (11; 11') extends in the longitudinal direction over several thread turns (8'), preferably over a range of 2 - 4 thread turns.

5. Connecting element according to one of claims 1 to 4, characterized in that the at least one broaching groove has a run-out area into the supporting thread turns on the side facing away from the thread end in the longitudinal direction.

6. Connecting element according to one of claims 1 to 5, characterized in that the at least one clearing groove is arranged parallel to a longitudinal axis of the shaft.

7. Connecting element according to one of claims 1 to 6, characterized in that a thread-free pin (14) is provided after the thread end (9), the pin (14) being smaller in diameter dz than the core diameter dl, wherein the diameter dz of the pin (14) is in particular in a range of 0.75 to 0.98 times the core diameter dl.

8. Connecting element according to claim 7, characterized in that the at least one reaming groove (10) ending below the core diameter dl in the shaft (2) at a diameter dy2 reaches in its depth at most the diameter dz of the pin (14).

9. Connecting element according to claim 7 or 8, characterized in that the pin (14) has a length of 0.2 - 0.45 times the nominal diameter dn, in particular 0.35 times.

10. Connecting element according to one of claims 1 to 9, characterized in that the external thread (3) is designed for a positive and non-positive as well as detachable connection with a nut component (40) having a corresponding internal thread (41), wherein the external thread (3) and the internal thread (41) correspond to the rules of a standard for screw connections.

11. Connecting element according to one of claims 1 to 10, characterized in that the broaching area (10) is produced without cutting and is free of machining marks caused by cutting tools.

12. Connecting element according to one of claims 1 to 11, characterized in that the external thread (3) and the at least one broaching area (10) are produced by rolling a blank (21) between rolling dies, wherein the blank (21) has at least one free space (22) along a blank shank (23).

13. Connecting element according to one of claims 1 to 12, characterized in that the clearing section (10) for thread end (9) has a transition region (15) extending over a length of at least one thread turn (8'), wherein the diameter of the transition region (15) decreases from the core diameter dl with at least one partially formed thread turn to a diameter ds and wherein the height of the thread turn decreases, in particular until the thread turn (8') disappears.

14. Connecting element according to one of claims 1 to 13, characterized in that the broaching groove (11) is concave in the groove base (17) and in the groove walls (18, 19) and in particular has a groove radius RI of 0.15 - 0.2 of a nominal diameter dn of the external thread (3).

15. Connecting element according to one of claims 1 to 14, characterized in that the proportion of the broaching grooves (11) in the thread turns over the circumference is between 15% and 50%.

16. Connecting element according to one of claims 1 to 15, characterized in that three clearing grooves (11, 11.1, 11.2) are arranged distributed over the circumference at an angle of 120°.

17. Screw connection, comprising a connecting element and a nut component, characterized in that the connecting element is designed according to one of claims 1 to 16 and that the nut component (40) has an internal thread (41) for receiving the connecting element.

18. Blank for the production of a connecting element according to one of claims 1 to 16, wherein the connecting element is provided with an external thread (3) with thread turns (12) with a nominal diameter dn and with a Core diameter dl can be produced by thread rolling, wherein the blank (21) has a shaft (23) with a first shaft section (24) with a diameter df for the external thread (3) to be produced, characterized in that in the first shaft section (24) towards a blank end at least one free space (22) is arranged along the shaft (23).

19. Blank according to claim 18, characterized in that a plurality of free spaces (22) are arranged spaced apart from one another distributed over the circumference.

20. Blank according to claim 19, characterized in that three free spaces (22) are arranged at an angle of 120° over the circumference.

21. Blank according to one of claims 19 to 20, characterized in that the proportion of free spaces (22) over the circumference is between 15% and 50%.

22. Blank according to one of claims 18 to 21, characterized in that the at least one free space (22) is arranged parallel to a longitudinal axis of the shaft (23).

23. Blank according to one of claims 18 to 22, characterized in that the at least one free space (22) is designed as a concave groove and that the groove in the groove base (17) and in the groove walls (18, 19) has a groove radius RI of 0.15 - 0.2 times a nominal diameter dn of the external thread (3) to be produced and that a convex transition with a transition radius R2 of the groove walls (18, 19) into a lateral surface of the shaft (23) is smaller than the groove radius RI, but is at least 0.2 times the groove radius RI.

24. Blank according to claim 23, characterized in that the transition radius R2 is at most half the groove radius RI.

25. Blank according to claim 24, characterized in that the transition radius R2 is at most one third of the groove radius RI.

26. Blank according to one of claims 18 to 25, characterized in that the at least one free space (22) extends over several thread turns (8) of the external thread (3) to be produced from this blank, preferably over a range of 2 to 5 thread turns (8).

27. Blank according to one of claims 18 to 26, characterized in that the at least one free space (22) has a run-out region (29) extending over several thread turns (8) of the external thread (3) to be produced from this blank (21), preferably over a region of 1 to 3 thread turns (8).

28. Blank according to one of claims 18 to 27, characterized in that the depth of the at least one free space (22) is determined such that the diameter dy2 of the at least one free space (22) ends below the core diameter dl of the external thread (3) to be produced from this blank (21) in the blank shaft (23), wherein the diameter dy2 of the at least one free space (22) is in particular in the range of 0.75 - 0.99 of the core diameter dl.

29. Blank according to one of claims 18 to 27, characterized in that the depth of the at least one free space (22) is determined such that the diameter dyl of the at least one free space (22) above the core diameter dl of the external thread (3) to be produced from this blank ends in the blank shaft (23).

30. Blank according to one of claims 18 to 29, characterized in that the blank (21) has a shaft section (26) towards the end of the blank, which tapers conically to a diameter dx smaller than the core diameter dl of the external thread to be produced (3) .

31. Blank according to one of claims 18 to 30, characterized in that a pin (28) with a diameter dz is arranged at the end of the blank, the diameter dz of the pin (28) being smaller than the core diameter dl of the external thread (3) to be produced from this blank (21).

32. Blank according to claim 31, characterized in that the diameter dz of the pin (28) with a metric thread according to DIN 13 is in a range from 0.68 to 0.9 times the diameter df of the blank shank (23).

33. Blank according to claim 31 or 32, characterized in that the depth of the at least one free space (22) extends at most to the diameter dz of the pin (28).

34. Blank according to one of claims 18 to 33, characterized in that the blank is produced by a pressing process.

35. Connecting element according to one of claims 1 to 16, characterized in that on the shaft (2) a head (4) with a drive (5) with force application surfaces (6), wherein the head (4) has a larger diameter than the shaft (2) and that on an underside (4.1) of the head facing the shaft (2) (4) a projection (4.2) projecting beyond the underside (4.1) is formed, which projection is arranged in the circumferential direction at a constant distance (r) around the shaft (2).

36. Connecting element according to claim 35, characterized in that the projection (4.2) has regions (4.4) of reduced height and / or is interrupted.

37. Connecting element according to claim 35 or 36, characterized in that the projection (4.2) has at least one cutting edge (4.3).

38. Connecting element according to claim 37, characterized in that the projection (4.2) has regions (4.4) with an interrupted cutting edge (4.3).

39. Connecting element according to one of claims 35 to 38, characterized in that the projection (4.3) is tapered, preferably in an angular range of 80° - 125°, in particular 105°.

40. Connecting element according to one of claims 35 to 39, characterized in that the underside (4.1) and / or the projection (4.3) is at least partially provided with a coating made of a material with particularly good electrical conductivity compared to the material of the connecting means or the workpiece with the nut thread, in particular Cu and / or Ni and / or Ag and / or Zn and / or Sn.

41. Blank according to one of claims 18 to 34 for the production of a connecting element according to one of claims 35 to 40, wherein the connecting element with an external thread (3) with thread turns (12) with a nominal diameter dn and with a core diameter dl can be produced by thread rolling, wherein the blank (21) has a shaft (23) with a first shaft section (24) with a diameter df for the external thread (3) to be produced, characterized in that a head (4) with a drive (5) with force application surfaces (6) is provided on the shaft (2), wherein the head (4) has a larger diameter than the shaft (2) and that on an underside (4.1) of the head (4) facing the shaft (2) there is formed a projection (4.2) projecting beyond the underside, which projection is arranged in the circumferential direction at a constant distance around the shaft (2).

42. Blank according to claim 41, characterized in that the projection is designed according to claims 36 to 39 and in particular has a cutting edge (4.3).

43. Blank according to claim 41 or 42, characterized in that the underside (4.1) and / or the projection (4.3) is at least partially provided with a coating made of a material with particularly good electrical conductivity compared to the material of the connecting means or the workpiece with the nut thread.

44. Screw connection, comprising a connecting element and a nut component, characterized in that the connecting element is designed according to one of claims 35 to 40 and that the nut component (40) has an internal thread (41) for receiving the connecting element.

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