Patent Publication Number: US-10773365-B2

Title: Installation tool for a wire thread insert having an installation pin that can be bent back, and installation method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage application pursuant to 35 U.S.C. § 371 of International Application No. PCT/EP2015/076755, filed Nov. 17, 2015, which claims priority upon German Patent Application No. 10 2014 223 905.2, filed Nov. 24, 2014, the entire contents of each application herein being incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention is related to an installation tool for a wire thread insert for mounting into a receiving thread of a component as well as an installation method for this wire thread insert in the component with receiving thread. 
     BACKGROUND OF THE INVENTION 
     In the prior art, different wire thread inserts for mounting into a receiving thread of a component are known. They are for example described in U.S. Pat. No. 2,363,789, EP-A-0 140 812 and EP-A-0 157 715. Consistently, the outer diameter of the cylindrical walls of the wire thread insert has to be chosen somewhat larger as the outer diameter of the receiving thread of the component. Therefore, the mounting of the wire thread insert into the receiving thread of the component has to occur by means of a diameter reduction of the wire thread insert. In this way it is ensured that a tight fit of the wire thread insert is achieved by means of the elastic re-deformation of the wire thread insert after installation in the receiving thread. 
     For facilitating the driving in of the wire thread insert into the receiving thread, a half winding at the end of the cylindrical coil of the wire thread insert is retracted or moved radially into the inside in known manner (EP-B1-0 228 981). The smallest outer diameter of the retracted section of the wire thread insert shall be almost equal to or somewhat larger as the corresponding outer diameter of the receiving thread in the component. Further, at this known wire thread insert, the wire cross-section is tapered at the end to facilitate the driving in of the wire thread insert into the receiving thread and to avoid damages of the thread bore in the component. 
     Different embodiments of wire thread inserts are also disclosed in EP-B1-0 983 445. A wire thread insert consists of a cylindrical coil with a plurality of helically wound windings. A first winding of this cylindrical coil leads to a mounting tang protruding linearly radially into the cylindrical coil. By means of a suitable installation tool, this mounting tang is grasped and thereby, the wire thread insert is screwed into the receiving thread of the component. After the installation has been completed, the mounting tang is removed by breaking-off the mounting tang in the first winding with the aid of a predetermined breaking point. In this way, a receiving thread with a continuously screwable wire thread insert results. 
     DE 1 016 066 B discloses a locking screw at which a wire thread insert is fastenable. For this purpose, the locking screw has a transverse slot at a front end in which a radially inwardly bent driving tang of the wire thread insert can be received. To be able to remove the locking screw from the wire thread insert, an inlying channel is provided in the locking screw which ends at the transverse slot. A pin can be inserted into this channel by means of which the driving tang can be pressed out of the transverse slot. At this, the driving tang is neither excessively deflected, broken or permanently deformed. Subsequently, the locking screw can be removed from the wire thread insert. 
     DE 10 2010 050 735 describes different alternatives of a wire thread insert with redressable but not removable tang. The tangs serve for installing the wire thread insert in a component opening with thread. After installation, the tang is redressed into the circumferential shape of the wire thread insert without obstructing later the screwing-in of a threaded bolt into the wire thread insert. The redressing occurs by means of an installation tool having a compressing blade. The compressing blade exerts a force onto the free front end of the tang and redresses it thereby. For facilitating the redressing, a bending portion between coil and tang of the wire thread insert comprises a tapered notch or a moving notch. The moving notch serves at the same time as tapering in the bending portion and as installation aid for the wire thread insert into the component opening. 
     Starting from the known wire thread inserts with redressable and not removable tang, it is the technical object of the present invention to provide an alternative and technically simple and resilient installation tool and an alternative installation method by means of which the wire thread insert is installable in a component opening with thread. 
     SUMMARY OF THE INVENTION 
     The above object is solved by the installation tool and the installation method according to the appending claims. Advantageous embodiments and developments of the present invention result from the appending claims, the description, as well as the accompanying drawings. 
     The inventive installation tools are adapted to a wire thread insert having a cylindrical coil with a plurality of helically wound windings of a wire. A first winding comprises a driving tang with moving notch protruding into an interior of the coil via a bending portion. The driving tang protrudes radially inwardly with respect to the coil and encloses an angle &lt;90° with a second winding of the coil extending in the course of direction of the driving tang. 
     According to a first alternative, the installation tool comprises the following features: a rotatable mounting spindle with a driving end for rotating the mounting spindle and a functional end for installing the wire thread insert, wherein the functional end comprises at least one turn which is reduced in length in circumferential direction and which has a driving edge at a first end for engagement into a moving notch of the wire thread insert and a bend-up-shoulder at a second end for bending the driving tang of the wire thread insert radially outwardly. 
     The installation tool comprises a known mounting spindle on the functional end of which the wire thread insert to be mounted can be fastened rotation-proof so that it can be screwed into a component opening with thread by rotating the mounting spindle. The rotation of the mounting spindle occurs by means of the driving end which is moved manually or by means of a motorized drive. On the functional end of the mounting spindle, the wire thread insert is fastenable rotation-proof in a rotation direction of the mounting spindle. In this context and on the one hand, it is preferred that the functional end comprises an appropriate outer thread so that the wire thread insert can be screwed onto this outer thread. According to another preferred embodiment, the functional end has an outer diameter which is smaller as the inner diameter of the wire thread insert. Due to this dimensioning it is possible to plug the wire thread insert onto the functional end of the installation tool. 
     At the functional end, which is arranged oppositely to the driving end of the mounting spindle, a turn is arranged which is reduced in its circumferential length. This means that at the functional end of the mounting spindle facing away from the driving end seen in longitudinal direction of the mounting spindle at least a last turn is reduced in its length such that this last turn does not extend over a rotation angle of 360° around the longitudinal axis of the mounting spindle. Contrary to this, the length-reduced turn extends in circumferential direction preferably over a length which is defined by a rotation angle of ≤270°, preferably ≤180°, around the longitudinal axis of the mounting spindle. 
     While the in circumferential direction at least one length-reduced turn forms a radial outer side for the abutment at the wire thread insert to be installed, the two opposing ends of the length reduced turn are formed as functional elements. At one end preferably the driving edge is present which is formed by a radial inner and a radial outer leg. The radial inner and the radial outer leg enclose preferably an angle &lt;90°. 
     At the other end of the at least one length-reduced turn, the bend-up-shoulder is arranged. The bend-up-shoulder comprises a web inclined radially inwardly and opposite to a drive-in direction of the mounting spindle which encloses with a radial outer edge of the mounting spindle preferably an angle &lt;90°. Due to its preferred acute-angled embodiment, the driving edge forms a blade-like guiding in drive-in direction of the wire thread insert which engages in the moving notch of the wire thread insert in a form-fit manner due to its arrangement. This form-fit engagement ensures a rotation-proof connection between mounting spindle and wire thread insert in drive-in direction or installation direction of the wire thread insert in the component opening. The bend-up-shoulder acts, on the contrary, only at a rotating of the mounting spindle against the installation direction, thus if the mounting spindle is removed rotatingly from the wire thread insert. Due to its preferred angled embodiment, the driving tang enters into an angle at the screwing-out of the mounting spindle which is formed by the bend-up-shoulder and the radially inner wall of the component opening. Upon further rotating, the bend-up-shoulder presses the driving tang against the radially inner component opening so that the driving tang is redressed permanently into the outer contour of the wire thread insert. At this, the bend-up-shoulder slides along the driving tang against the drive-in direction of the wire thread insert. 
     To support this redressing of the driving tang advantageously, the bend-up-shoulder is formed curvilinear according to a preferred embodiment of the present invention. Accordingly, the bend-up-shoulder comprises with respect to the installation spindle in its course radially inwardly an increasing curvature. Further, it is preferred that the bend-up-shoulder is connected integrally to the driving edge by means of the at least one length-reduced turn. 
     The present invention comprises a further alternative of the installation tool for the wire thread insert. The wire thread insert consists of a cylindrical coil with a plurality of helically wound windings of a wire in which a first winding comprises a driving tang with moving notch protruding into an interior of the coil via a bending portion. The installation tool comprises the following features: a rotatable mounting spindle with a driving end for rotating the mounting spindle and with a functional end for installing the wire thread insert in a component opening, in which the functional end comprises a first threaded portion having a first core diameter and a second threaded portion having a second core diameter, wherein the first threaded portion is arranged between the driving end and the second threaded portion, wherein the second core diameter is larger as the first core diameter and wherein the functional end comprises a recess in a turn which forms an undercut for the driving tang of the wire thread insert in drive-in direction of the wire thread insert. 
     The second inventive alternative of the installation tool is characterized by a functional end with two threaded portions adjacent to each other. The first threaded portion serves substantially for receiving the wire thread insert to be installed. If the wire thread insert is arranged in this threaded portion it is preferably installed in a component opening of a component. The second threaded portion having a larger core diameter as the first threaded portion is arranged such that this second threaded portion has to be screwed through the installed wire thread insert at the removing of the mounting spindle from the installed wire thread insert. Due to the larger core diameter of the second threaded portion which forces its way through the wire thread insert at the screwing out of the mounting spindle out of the wire thread insert, the driving tang with moving notch is redressed radially outwardly into the circumferential outer contour of the wire thread insert. As preferably different mechanical tension conditions are superimposed in the bending portion, the driving tang is redressed permanently into the circumferential contour of the wire thread insert. Preferably, and after the redressing, the driving tang is arranged in the outer contour of the wire thread insert or in the thread of the mounting opening of the wire thread insert precisely tailored or true to size or true to gauge. 
     For holding the wire thread insert which is spindled or plugged onto the functional end during the mounting rotation-proof, the above-mentioned recess is provided. This recess is preferably arranged in the first threaded portion, preferably within a rotation angle of 270° starting at or adjacent to the second threaded portion. The radially inwardly bent driving tang with moving notch snaps into this recess at the spindling or plugging of the wire thread insert onto the functional end. With the arrangement of the recess spaced from the second threaded portion it is guaranteed that only at the de-spindling of the mounting spindle out of the installed wire thread insert the second threaded portion in combination with the radially inner wall of the component opening creates sufficient mechanical tensions in the driving tang which redress the driving tang permanently. 
     It is further preferred that the second core diameter is at least 0.1% larger as the first core diameter, preferably in a range of 0.1% to 2% larger as the first core diameter. According to a further preferred embodiment of the present alternative of the installation tool, the second threaded portion extends over a rotation angle of at least 180° around the longitudinal axis of the mounting spindle. 
     The present invention comprises further an installation method of the wire thread insert with redressable, not removable driving tang and a moving notch by means of an installation tool in a receiving thread of a component, which comprises the following steps: spindling or plugging the wire thread insert onto a functional end of a mounting spindle of the installation tool such that the moving notch couples in a form-fit manner to a driving edge or a radial recess of the installation tool and connects the wire thread insert rotation-proof with the installation tool, driving-in of the wire thread insert into the receiving thread by rotating the mounting spindle in a first rotation direction, redressing the driving tang into the receiving thread by rotating the mounting spindle in a second rotation direction and de-spindling or removing the mounting spindle from the wire thread insert with redressed driving tang. 
     As part of the installation method it is further preferred that a radial redressing of the driving tang occurs by means of a bend-up-shoulder or a second threaded portion with enlarged core diameter compared to a first threaded portion at the functional end of the mounting spindle. 
    
    
     
       SHORT DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
       The different/preferred embodiments of the present invention are explained in detail with reference to the accompanying drawings. It shows: 
         FIG. 1  a front end view of a preferred embodiment of the wire thread insert with redressable driving tang and moving notch, 
         FIG. 2  a front end view of a further preferred embodiment of a wire thread insert with redressable driving tang and moving notch, 
         FIG. 3  a perspective view of a preferred wire thread insert with redressed driving tang and with moving notch, 
         FIG. 4  a front end view of a preferred first alternative of the inventive installation tool, 
         FIG. 5  a front end view of a further preferred first alternative of the installation tool, 
         FIG. 6  a cross-sectional side view of the preferred first alternative of the installation tool, 
         FIG. 7  a cross-sectional side view of a preferred second alternative of the installation tool, 
         FIG. 8  a schematic view of the two threaded portions of the preferred second alternative of the installation tool, and 
         FIG. 9  a flowchart of a preferred embodiment of the inventive installation method of the wire thread insert into an inner thread of a component opening of a component with an installation tool. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is related to different alternatives of an installation tool for mounting or installing a wire thread insert  1  into a component opening with inner thread of a component. The usage and dimensioning of wire thread inserts  1  is known in the prior art. 
     The inventive wire thread insert  1  is wound of a wire of known material and known cross-sectional shape. With reference to  FIGS. 1 to 3 , the wire thread insert  1  comprises a cylindrical coil  20  consisting of a plurality of helically wound windings  30 . The coil  20  has a first end  22  and a second end  24 . A driving tang  50  with moving notch  42  is arranged at the first end  22  of the cylindrical coil  20  which protrudes in a radial plane of the cylindrical coil  20  into the interior of the cylindrical coil  20 . 
     The driving tang  50  is connected to a first winding  32  of the cylindrical coil  20  at its first end  22  via a bending portion  40 . The driving tang  50  does not protrude linearly radially into the interior of the cylindrical coil  20 , as can be seen based on  FIGS. 1 and 2 . Instead, the driving tang  50  has almost the shape of a circular arc. The circular arc of the driving tang  50  has preferably the same radius or a larger radius as the cylindrical coil  20  so that the driving tang  50  is permanently redressable from the interior of the cylindrical coil  20  into the course of the first winding  32 . It is also preferred to form the circular arc of the driving tang  50  with a radius which differs ±1% from the radius of the cylindrical coil  20  at the maximum. Further, the driving tang  50  encloses an angle α with the circumferential contour of the wire thread insert. Preferably, the angle α is smaller than 90° and forms an acute angle. It has turned out that when the driving tang  50  has a length of 0.2 U to 0.4 U, it can be redressed advantageously into the circumferential contour of the wire thread insert  1  from an angle α of 5°≤α≤50°, preferably 1°≤α≤35°. At this, it has an advantageous effect that the driving tang  50  abuts with its length at the installation tool (see below) by means of friction. Thereby, a multi-axial mechanical tension condition is transferred into the bending portion  40  which ensures the permanent redressing of the driving tang  50 . In the case of a driving tang  50  with a preferred length L Z  of 0.05 U≤L Z ≤0.1 U, the driving tang  50  is preferably arranged in an angle range of 5°≤α≤45°, preferably 5°≤α≤30°. The dimension U designates the circumference of the wire thread insert  1 , which can be calculated from the radius or the diameter of the wire thread insert  1 . 
     The bending portion  40  has the function to connect the driving tang  50  with the remaining of the wire thread insert  1  in a bendable and tensile-rigid manner. Thereby it is ensured that during installing the wire thread insert  1  into a receiving thread A of a component B a sufficient high torque can be applied onto the wire thread insert  1  by means of the driving tang  50 . Based on this constructive configuration the wire thread insert  1  can be drawn into the receiving thread A by means of the driving tang  50  without that the driving tang  50  breaks. To transmit the required torque onto the wire thread insert for the driving in of the wire thread insert into the component opening, the wire thread insert comprises the moving notch  42 . The moving notch  42  consists of a radial recess at a radial inner side of the bending portion  40  in drive-in direction R (see  FIGS. 1, 2 ). The moving notch  42  comprises an undercut  43  in drive-in direction R which allows a rotation-proof coupling (in drive-in direction R) of an installation tool (see below) to the moving notch  42  and a rotating of the wire thread insert  1  as well. Preferably, the moving notch  42  is positioned such that the undercut  43  is arranged within the circumferential contour of the wire thread insert  1 . Preferably, the undercut  43  protrudes radially inwardly beyond the inner edge  25  of the wire thread insert  1 . In this way, a coupling between installation tool and wire thread insert is supported. 
     Further, the bending portion  40  ensures that the driving tang  50  is permanently redressable into the receiving thread A of the component B or generally into the course of the first winding  32 . To this end, the bending portion  40  has the same mechanical, thermal, chemical and geometric characteristics as the wire of the cylindrical coil  20 . By means of a suitable installation tool (see below) the driving tang  50  is bent in a radial direction out of the interior of the cylindrical coil  20  at the redressing without that the driving tang  50  returns thereafter elastically into the interior of the cylindrical coil  20 . This condition is shown in  FIG. 4 . 
     For facilitating the redressing of the driving tang  50  into the receiving thread A or into the course of the first winding  32 , preferably the wire in the bending portion  40  is modified in its bending characteristics compared to the wire of the cylindrical coil  20 . This modification of the bending portion  40  is created chemically, geometrically, formally, chemically or in any other manner according to different embodiments of the present invention. 
     According to the preferred embodiment shown in  FIGS. 2 and 3 , the wire of the bending portion  40  is tapered in its cross-section compared to the wire of the cylindrical coil  20 . This is realized by means of the moving notch  42 . The tapering or notch  42  is formed such that a low notch factor at the bending of the driving tang  50  is created and thus the driving tang  50  does not break during the bending. The moving notch  42  is arranged at the radial inner side of the bending portion  40 . The moving notch is formed and positioned such that it can enter into a driving blade or edge which is present in the contour of the drive-in tool for driving the wire thread insert  1  into a receiving thread and locks there in a form-fit manner. As can be seen in  FIGS. 2 and 3 , the upstream side of the moving notch  42  in drive-in direction of the wire thread insert  1  forms an undercut at which the driving blade abuts in a form-fit manner. The radially inwardly bent driving tang  50  supports the engagement of the driving blade or edge in the moving notch  42  because at least the side of the moving notch  42  being upstream in screw-in or drive-in direction protrudes beyond the circumferential contour radially inwardly into an interior of the wire thread insert  1 . Thus, the moving notch  42  realizes two functions at the same time. On the one hand, it makes the engagement and locking of the driving blade or edge of an installation tool for the wire thread insert  1  possible. On the other hand, it provides a tapering of the bending portion  40  which supports a bending of the driving tang  50  into the receiving thread of the component. 
     For reducing the mechanical moment of resistance or the elastic moment of restoration of the wire in the bending portion  40 , for example from up to 2.000 MPa to about 400 MPa, the bending portion is mechanically processed. Suitable methods comprise the notching, milling, punching, forging, grinding, polishing, cold punching, pickling, lapping, to reduce the cross-section of the bending portion  40 . At the same time, it has to be ensured that the corrosion characteristics in the bending portion  40  are restored after the processing. 
     The preferred wire thread insert  1  can be characterized in summary as follows: wire thread insert  1  for mounting in a receiving thread of a component which comprises the following features: a cylindrical coil  20  consisting of a plurality of helically wound windings  30  of a wire comprising a first  22  and a second end  24 , wherein a first winding  32  provided at the first end  22  comprises a driving tang  50  with a moving notch  42  protruding into an interior  26  of the coil  20  via a bending portion  40 , and wherein the driving tang  50  is connected to the first winding  32  inseparably, is redressable by means of the bending portion  40  from the interior  26  of the coil  20  and the wire thread insert  1  is installable by means of the moving notch  42  and the driving tang  50 . Further preferred, the driving tang  50  of the wire thread insert  1  is redressable into the receiving thread A of the component B permanently. It is further preferred that the driving tang  50  is a circular arc, the tang radius of which is almost equal to a radius of the first winding  32  of the cylindrical coil  20 . For further constructive details of the wire thread insert, it is referred to DE 10 2010 050 735, which is hereby incorporated as reference. 
     Based on the above-described embodiment of the bending portion  40  and the shape of the driving tang  50 , the driving tang  50  of a wire thread insert  1  installed in a receiving thread A of the component B can be bent out of the interior of the cylindrical coil  20  so that the receiving thread A with the wire thread insert  1  is true to gauge. This means that a screw or a thread plug gauge can be screwed into the receiving thread A with the wire thread insert  1  with a negligible low additional torque or frictional moment due to the redressed driving tang  50 . The accuracy to gauge of the receiving thread A with the wire thread insert  1  can be demonstrated in that a manual driving-in of the thread plug gauge according to tolerance class  6 H, preferably of tolerance class  5 H, is ensured. 
     According to different embodiments of the present invention, the driving tang  50  is formed with different lengths (see above). In the redressed condition according to  FIG. 3 , the driving tang  50  extends over a circular arc A RZ  with a length L Z  of 0.05 U≤L Z ≤0.4 U, preferably 0.2 U≤L Z ≤0.4 U or 0.05 U≤L Z ≤0.1 U. At this, U denotes the outer circumference of the wire thread insert. The length L Z  of the driving tang is measured always starting at the bending portion  42  to the free end of the driving tang  50 . 
       FIGS. 1 and 2  show two preferred embodiments of a wire thread insert  1  which are installed in a component opening by means of the installation tools described below in greater detail.  FIG. 3  shows schematically a wire thread insert  1  with redressed driving tang  50  as it would be arranged installed in a component opening. 
     The wire thread insert  1  is mounted into the component opening with thread (not shown) by means of an installation tool  60 ;  60 ′. Two alternatively preferred constructions of the installation tool  60 ;  60 ′ are schematically shown in  FIGS. 4-6 and 7-8 . At the description of the alternative installation tool  60 ;  60 ′, the same constructive details are denoted with the same reference signs. Further, descriptions of these same constructive details apply equally for both alternatives of the installation tool  60 ;  60 ′ even if they have been discussed only in combination with one alternative. 
     The installation tool  60 ;  60 ′ comprise always a rotatable mounting spindle  62  with a driving end  64  and a functional end  70 ;  70 ′. The mounting spindle  62  is rotatable by means of the driving end  64  manually or mechanically with a respective, for example electro-motoric, drive (not shown). First of all, the wire thread insert  1  is fastened or arranged (step S 1 ) on the functional end  70 ;  70 ′. For this purpose, the wire thread insert  1  is taken between thumb and forefinger and the functional end  70 ;  70 ′ of the mounting spindle  62  is screwed into the wire thread insert  1 . At this, the functional end  70 ;  70 ′ enters at the front end of the wire thread insert  1  which is arranged opposite to the front end of the wire thread insert  1  with driving tang  50 . Depending on whether the wire thread insert  1  comprises a clockwise or counter-clockwise thread, the mounting spindle  62  is rotated clockwise or counterclockwise. 
     According to another preferred embodiment of the present invention, the functional end  70 ;  70 ′ of the mounting spindle  62  is provided with a diameter which is smaller as an inner diameter of the wire thread insert  1 . In this case, the wire thread insert  1  is plugged onto the functional end  70 ;  70 ′ to fasten or arrange it on or at the mounting spindle  62 . Although in this case the accuracy to gauge of the mounted wire thread insert is affected, a driving-in of a screw into the installed wire thread insert is possible. 
     A preferred embodiment of the first alternative of the installation tool  60  is shown in  FIGS. 4-6 . The functional end  70  of the mounting spindle  62  comprises a threaded section  72  formed compatible to the wire thread insert  1 . The threaded section  72  extends, beginning at the free end of the mounting spindle  62 , preferably over at least a partial length of the functional end  70 . This partial length corresponds according to an embodiment of the present invention at least to an axial length of the wire thread insert  1  so that it can be spindled onto the functional end  70  in its full length. It is also preferred to form the threaded section  72  shorter. In this case, the threaded section  72  is followed in fastening direction B of the wire thread insert  1  on the functional end  70  by a receiving portion  74  having a smaller diameter compared to the threaded section  72 . This receiving portion  74  allows a ramping and later supporting and guiding of the wire thread insert  1  without that the function of the threaded section  72  is restricted. 
     The threaded section  72  comprises a circumferential turn which extends coil-like around the mounting spindle  62  at the functional end  70 . The turn is formed by two radially outwardly protruding flanks arranged opposite to each other, between which the coil-like bent wire of the wire thread insert  1  is guided. Near the free end of the functional end  70 , which is facing away from the driving end  64 , the turn  72  is open (aperture  73 ). Within this aperture  73 , the wire of the wire thread insert  1  is not supported or guided on two sides by flanks of the turn over the length portion of a rotation angle γ of preferably at least 360°. Due to this aperture  73  or the at least on one-side flank less length portion defined by the angle γ and the diameter of the functional end  70 , the functional end  70  comprises a length-reduced first turn  72   a  and a second turn  72   b.    
     The aperture  73  is formed by a front end axial extension  80  of the functional end  70  which protrudes opposite to the fastening direction B of the wire thread insert  1  from the front end of the functional end  70 . The extension  80  extends only over a part of the front end, as can be seen in  FIGS. 4 and 5 . Due to this, a part of the front end face of the functional end  70  is set back behind the extension  80  whereby the aperture  73  is created. 
     The extension  80  is defined along a circumferential length by the length-reduced first turn  72   a . Preferably, the length-reduced first turn  72   a  and thus the one side of the extension  80  extends over an arc-length S defined by an angle β. The angle β has a preferred amount of 150°≤β≤240°. 
     In drive-in direction R of the functional end  70  into the wire thread insert  1 , the front end of the length-reduced first turn  72  and thus also the front end of the extension  80  comprises a driving edge  82 . The driving edge  82  extends preferably parallel to the longitudinal axis of the mounting spindle  62 . The course of the driving edge  82  can also differ from this orientation as long as the functional cooperation between moving notch  42  and driving edge  82  is ensured. In case the functional end  70  is screwed in drive-in direction R into the wire thread insert  1  with moving notch  42  (step S 1 ), the driving edge  82  enters independently into the moving notch  42  (step S 2 ). At this, the driving edge  82  engages the undercut  43  so that a rotation-proof connection between mounting spindle  62  and wire thread insert  1  is created in drive-in direction R. The rotation-proof connection ensures that the wire thread insert  1  is rotated by means of a rotation of the mounting spindle  62  as well and can be installed in an inner thread of a component opening of the component in this way. Preferably, the driving edge  82  is arranged radially inwardly displaced with respect to a core radius r K  of the length reduced first turn  72   a . The core radius r K  is shown in  FIGS. 4 and 5 . It is defined by the distance between the central axis of the mounting spindle  62  and the radial outer edge of the thread core or the bottom of the turn  72   a ,  72   b . Preferably, the driving edge  82  is spaced by the length l MK  from the central axis of the installation spindle  62 . The length l MK  comprises preferably a range of r K &gt;l MK ≥1.4 r K  to ensure an ideal cooperation of the moving notch  42  and the driving edge  82 . 
     As soon as the driving edge  82  engages the moving notch  42  of the wire thread insert  1 , the mounting spindle  62  rotates the wire thread insert  1  as well. During this screwing-in or driving-in of the wire thread insert  1  into a component opening (step S 3 ) the driving edge  82  drags the wire thread insert  1  in drive-in direction R due to the rotation-proof engagement at the undercut  43 . At this, the first winding  32  which follows the driving tang  50  engages at the length-reduced first turn  72   a  and forms with it an additional frictional connection. This frictional connection supports the transfer of the installing torque from the mounting spindle  62  to the wire thread insert  1 . Because the torque for installing and to be transferred to the wire thread insert  1  is distributed thereby to the driving edge  82  and the length-reduced first turn  72   a . Therefore, it is preferred to adjust the length of the length-reduced first turn  72   a  (see angle β, above) depending on the torque to be transferred. From this it follows that at a higher torque to be transferred between installation spindle  62  and wire thread insert  1 , the length-reduced first turn  72   a  has to be formed longer compared to a smaller torque to be transferred. 
     Preferably, the driving edge  82  is formed by a radially inner and radially outer leg. These two legs enclose an angle of &lt;90°, preferably &lt;50° and further preferred &lt;40°. It is also preferred that the length-reduced first turn  72   a  extends into an axial web which forms due to its width the driving edge  82 . 
     The length-reduced first turn  72   a  extends at its end facing away from the screw-in or drive-in direction R into a bend-up shoulder. The bend-up shoulder  84  consists of a face which is oriented straight angularly with respect to the core radius r K  (not shown) or of a curvilinear face. The bend-up shoulder  84  forms an axial boundary face  85  of the extension  80 . Preferably the bend-up shoulder  84  encloses with the outer edge of the mounting spindle  62  an angle δ&lt;90°, preferably 90°&gt;δ&gt;30°. If the bend-up shoulder  84  consists of a curvilinear face, the angle δ is measured between the tangent T δ  at the face  85  at the intersection with the outer edge of the mounting spindle  62  and the outer edge of the mounting spindle  62  (see  FIGS. 4 and 5 ). Further preferred, the bend-up shoulder  84  is formed curvilinear. The curvilinear formed bend-up shoulder  84  comprises with respect to the installation spindle  62  in the course radially inwardly an increasing curvature. 
     According to a further preferred embodiment, the bend-up shoulder  84  is integrally connected via the length-reduced turn  72   a  and directly to the driving edge  82 . In this way, the extension  85  is formed stable and forms an additional radial support for the length reduced first turn  72   a.    
     After the wire thread insert  1  has been screwed into the component opening with thread to a sufficient depth, the mounting spindle  62  is rotated against the screw-in or drive-in direction R (step S 4 ). At this, the engagement of the driving edge  82  is released from the moving notch  42 . Upon further rotating of the mounting spindle  62  and thus of the functional end  72 , the bend-up shoulder  84  comes into abutment with the driving tang  50 . By means of the further rotating of the functional end  70  against the drive-in direction R, the bend-up shoulder  84  presses the driving tang  50  radially outwardly into the circumferential contour of the wire thread insert  1 . At this, the driving tang  50  slides on the axial face  85  of the bend-up shoulder  84 . During the redressing of the driving tang  50  (step S 5 ) the bending portion  40  is mechanically stressed such that the driving tang  50  is redressed permanently into the circumferential contour of the wire thread insert  1 . Thus, at de-spindling or screwing the mounting spindle  62  out of the wire thread insert  1 , the bend-up shoulder  84  bends the driving tang  50  which is weakened by the moving notch  42  radially into the inner thread of the component opening. The driving tang  50  is thus bent radially to the outside permanently and beyond the enclosing contour of a screw and a thread plug gauge. The drive-in torque of a screw into the wire thread insert  1  with redressed driving tang  50  is almost zero. The accuracy to gauge of the wire thread insert  1  with redressed tang  50  achieved in this way means that the redressed tang  50  does not interfere with the thread provided by the wire thread insert  1 . The evidence for such an accuracy to gauge takes place according to tolerance class  6 H, based on which the plug gauge is manually screwed into the installed wire thread insert  1  with redressed tang  50  (see also ISO standard 965-1). 
     A preferred embodiment of the second alternative of the installation tool is schematically shown in  FIG. 6 . In contrast to the first alternative of the installation tool, it has another functional end  70 ′. The preferred functional end  70 ′ comprises a first  90  and a second threaded portion  92  which are arranged adjacent to the free end of the functional end  70 ′ opposite to the driving end  64 . Preferably, both threaded portions  90 ,  92  are arranged directly adjacent to each other to ensure a frictionless transfer of the wire thread insert  1  between the threaded portions  90 ,  92  at the screwing-on and screwing-off from the functional end  70 ′. It is also preferred to arrange the two threaded portions  90 ,  92  axially spaced from each other on the functional end  70 ′. 
     In the second threaded portion  92 , a thread fitting to the shape of the wire coil of the wire thread insert  1  is provided. This thread of the second threaded portion  92  has the same characteristics as the turn  72   b  of the functional end  70  (see above). By means of the shape and dimension of the thread adapted to the wire thread insert  1 , the wire thread insert  1  can enter without problems into the second threaded portion  92 . The second threaded portion  92  can be characterized by a core radius r K2 , as shown in  FIG. 7 . The core radius r K2  defines the distance between the longitudinal axis of the functional end  70 ′ and the radial outer side of the threaded core of the second threaded portion  92 . 
     As can be seen based on  FIGS. 7 and 8 , a thread core of the first threaded portion  90  is larger as the thread core of the second threaded portion  92 . Especially, the core radius r K1  of the first threaded portion  90  is larger as the core radius r K2  of the second threaded portion  92 . Preferably, the core radius r K1  is larger as the core radius r K2  by the factor F so that it applies r K1 =F r K2 . The factor F varies preferably in a range of 1/1000≤F≤ 5/100, further preferred in the range 1/100≤F≤ 3/100 and at most preferred in the range of 2/1000≤F≤ 2/100. Correspondingly it results that the first core diameter 2r K1  is at least 0.1% larger as the second core diameter 2r K2 , preferably in a range of 0.1% to 2% larger as the first core diameter 2r K1 . 
     The first threaded portion  90  or the turn of the first threaded portion  90  extends at least over a rotation angle ω≥180° around the longitudinal axis of the mounting spindle  62 . Corresponding to the rotation direction of the first threaded portion  90 , this angle ω is measured clockwise or counterclockwise. Preferably, the first threaded portion  90  extends over a rotation angle in the range of 180°≤ω≤720°. 
     The second threaded portion  92  comprises a radial recess  94  in which the moving notch  42  with undercut  43  engages. As the driving tang  50  is bent radially inwardly, the moving notch  42  locks due to its inherent coil tension into the recess  94  upon spindling of the wire thread insert  1  onto the functional end  70 ′. As the recess  94  is preferably chamfered, a rotation-proof connection results in screw-in or drive-in direction R between the functional end  70 ′ and the wire thread insert  1 . 
     The radial recess  94  is preferably formed as bore, cut or electric discharge machining. Further, it is preferred to extend the recess  94  along the turn of the second threaded portion  92  over a certain length. This length corresponds according to an embodiment of the present invention to the length of the driving tang  50  so that it may be retained more easily in a rotation-proof manner in the recess  94 . 
     While the recess  94  is preferably arranged in the second threaded portion  92 , it could also be arranged in the first threaded portion  90 . 
     For installing the wire thread insert  1  in a component opening with inner thread, the wire thread insert  1  is spindled or screwed onto the functional end  70 ′. This occurs manually or mechanically. As the wire thread insert  1  may expand radially during the spindling because it is not limited by a component wall, the wire thread insert  1  is spindled without a specific mechanical effort onto the first  90  and the second threaded portion  92  (step S 1 ). At the end of the spindling, the driving tang  50  and/or the moving notch  42  engage in a rotation-proof manner with the recess  94  and thus with the functional end  70 ′ (step S 2 ). 
     Subsequently, the wire thread insert is screwed into the desired depth of the inner thread of the component opening by means of the mounting spindle  62  (step S 3 ). For de-spindling the wire thread insert  1  from the mounting spindle  62 , the mounting spindle  62  is rotated against the drive-in direction R (step S 3 ). At this, first of all the second threaded portion  92  and then the first threaded portion  90  is screwed out of the wire thread insert  1 , wherein the first threaded portion  90  passes through the complete wire thread insert  1 . 
     During the screwing out or de-spindling (step S 4 ), first of all the moving notch  42  is pressed radially out of the recess  94 . As soon as the first threaded portion  90  reaches the driving tang  50 , the larger core radius r K1  urges the driving tang  50  radially to the outside such that it is redressed permanently into the inner thread of the component opening or the circumferential contour of the wire thread insert  1  (step S 5 ). As preferably the moving notch  42  presents a weakening of the bending portion  40  of the wire thread insert  1 , it supports the redressing of the driving tang  50 . 
     Due to the enlarged core diameter or core radius r K1  of the first threaded portion  90 , the driving tang  50  receives beside the radially outwardly directed bending force an additional tangential application of force by means of the friction of the driving tang  50  at the radially outer side of the two threaded portions  90 ,  92 , especially by the threaded portion  90 . Due to this friction-caused additional application of force, preferably in the bending portion  40 , a multi-axial mechanical tension condition is achieved. This causes an exceeding of the material yield strength in the bending portion  40  so that a permanently radial redressing of the driving tang  50  is realizable. Due to this, the driving tang  50  can be bent radially to the outside permanently beyond the enclosing contour of a screw and a thread plug gauge and can be calibrated there. The drive-in torque for such a redressed driving tang  50  and the wire thread insert  1  arranged thereby in the component opening is almost zero. The evidence of this accuracy to gauge is performed preferably by screwing in a plug gauge with manual force according to tolerance class  6 H (see also ISO standard 965-1). 
     The individual steps of the installation method for the wire thread insert  1  in the component opening are schematically summarized according to a preferred embodiment in the flowchart of  FIG. 9 . 
     LIST OF REFERENCE SIGNS 
     
         
           1  wire thread insert 
           20  coil 
           22  first end 
           23  second end 
           30  winding 
           40  bending portion 
           42  moving notch 
           43  undercut 
           50  driving tang 
           60 ;  60 ′ installation tool 
           62  mounting spindle 
           70 ;  70 ′ functional end 
           72  threaded section 
           72   a  first length reduced turn 
           72  second turn 
           73  aperture 
           74  receiving portion 
           80  front-end extension 
           82  driving edge 
           84  bend-up-shoulder 
           85  axial boundary face of the bend-up-shoulder 
           90  first threaded portion 
           92  second threaded portion 
           94  recess 
         r K1 , r K2  core radius 
         R drive-in direction of the mounting spindle into the wire thread insert 
         B fastening direction of the wire thread insert onto the functional end 
         S arc length 
         r K  core radius 
         α angle in the wire thread insert 
         β angle of the length reduced first threaded portion  72   a    
         γ angle of the aperture  73