Abstract:
An insert for use in allowing spark plugs, fasteners, couplings for hydraulic fittings and pipe threads of a given dimension to be used in a material.

Description:
FIELD OF THE INVENTION 
     The following invention relates to generally to thread repairs in machinery, particularly cast metal machines. More specifically, the instant invention is directed to a thread repair sleeve having a substantially cylindrical shape and interior and exterior threads used to replace damaged threads in a casting. The focal point is prevention of removal of the insert once installed. 
     BACKGROUND OF THE INVENTION 
     Conventional repair techniques for stripped threads includes retapping the thread. While this type of repair is effective in some situations, grossly damaged threads are usually replaced with new threads defining a larger diameter bore. This, of course, necessitates the utilization of a larger fastener within the newly threaded bore which is undesirable particularly when the element to be inserted within the threaded bore is standardized, such as a spark plug. 
     The following prior art reflects the state of the art of which applicant is aware and is included herewith to discharge applicant&#39;s acknowledged duty to disclose relevant prior art. It is stipulated, however, that none of these references teach singly nor render obvious when considered in any conceivable combination the nexus of the instant invention as disclosed in greater detail hereinafter and as particularly claimed. 
     
       
         
               
               
               
               
             
               
             
               
               
               
               
             
           
               
                   
                   
               
               
                   
                  INVENTOR 
                 PATENT NO 
                 ISSUE DATE 
               
               
                   
                   
               
             
             
               
                   
                  Foster 
                 83,371 
                 October 27, 1868 
               
               
                   
                 Harvey 
                 154,864 
                 September 8, 1874 
               
               
                   
                 Harvey 
                 250,728 
                 December 13, 1881 
               
               
                   
                 Patten 
                 310,462 
                 January 6, 1885 
               
               
                   
                 Ball 
                 568,277 
                 September 22, 1896 
               
               
                   
                 Farr 
                 638,326 
                 December 5, 1899 
               
               
                   
                 Riggs 
                 678,814 
                 JuIy 16, 1901 
               
               
                   
                 Smith 
                 899,916 
                 September 29, 1908 
               
               
                   
                 Wells 
                 1,345,425 
                 July 6, 1929 
               
               
                   
                 Anderson, Jr., et al. 
                 1,408,793 
                 March 7, 1922 
               
               
                   
                 Brubaker, Jr. 
                 1,434,870 
                 November 7, 1922 
               
               
                   
                 Bayer 
                 1,539,628 
                 May 26, 1925 
               
               
                   
                 Hanson 
                 1,543,007 
                 June 23, 1925 
               
               
                   
                 Bergstrom 
                 1,963,542 
                 June 19, 1934 
               
               
                   
                 Harmen 
                 2,011,484 
                 August 13, 1935 
               
               
                   
                 Hays 
                 2,121,692 
                 June 21, 1938 
               
               
                   
                 Kirby 
                 2,291,162 
                 July 28, 1942 
               
               
                   
                 Poeton 
                 2,300,310 
                 October 27, 1942 
               
               
                   
                 Michaels 
                 2,361,701 
                 October 31, 1944 
               
               
                   
                 Murphy 
                 2,506,233 
                 May 2, 1950 
               
               
                   
                 Javor 
                 2,649,650 
                 August 25, 1953 
               
               
                   
                 Diperstein 
                 2,951,506 
                 September 6, 1960 
               
               
                   
                 Diperstein 
                 2,998,645 
                 September 5, 1961 
               
               
                   
                 Forsythe 
                 3,066,400 
                 December 4, 1962 
               
               
                   
                 Matthews 
                 3,117,486 
                 January 14, 1964 
               
               
                   
                 Waltermire 
                 3,295,580 
                 January 3, 1967 
               
               
                   
                 Dalke, et al. 
                 3,660,233 
                 May 2, 1972 
               
               
                   
                 Holmes 
                 4,074,950 
                 February 21, 1978 
               
               
                   
                 Reppert 
                 4,165,904 
                 August 28, 1979 
               
               
                   
                 Grenell 
                 4,271,554 
                 June 9, 1981 
               
               
                   
                 Burke 
                 4,295,765 
                 October 20, 1981 
               
               
                   
                 Diperstein 
                 4,599,781 
                 July 15, 1986 
               
               
                   
                 Reed 
                 4,662,806 
                 May 5, 1987 
               
               
                   
                 Lee, et al. 
                 4,810,149 
                 March 7, 1989 
               
               
                   
                 Casazza 
                 4,824,279 
                 April 25, 1989 
               
               
                   
                 Reed 
                 4,845,828 
                 July 11, 1989 
               
               
                   
                 Giannuzzi 
                 4,892,429 
                 January 9, 1990 
               
               
                   
                 Choe 
                 5,033,919 
                 July 23, 1991 
               
               
                   
                 Reed 
                 5,379,505 
                 January 10, 1995 
               
               
                   
                 Reed 
                 5,499,892 
                 March 19, 1996 
               
             
          
           
               
                 FOREIGN PRIOR ART 
               
             
          
           
               
                   
                    Arenz 
                 350,141 
                 June, 1931 
               
               
                   
                 unknown 
                 456,481 
                 December, 1950 
               
               
                   
                 Metalock 
                 154,074 
                 November, 1953 
               
               
                   
                 Betpob 
                 492,389 
                 January 22, 1976 
               
               
                   
                 Makchmob 
                 975,270 
                 November 23, 1982 
               
               
                   
                   
               
             
          
         
       
     
     OTHER PRIOR ART (Including Author, Title, Date, Pertinent Pages, Etc.) Time-Sert® and Big-Sert® advertisement, Screw Thread Inserts, 1999, entire advertisement. 
     Keen-Serts® advertisement, Solid Inserts, 1996, entire advertisement. 
     Heli-Coil advertisement, Screw Thread Inserts, 1998, entire advertisement. 
     SUMMARY OF THE INVENTION 
     The instant invention resolves the problems noted hereinabove and others by the provision of an insert which threads into new threads formed within the bore that is being repaired. The insert is a substantially cylindrical construct having an exterior thread which meshes with the newly threaded bore of the casting and an interior bore having threads complemental to the dimension of the preexisting fastener previously residing within the old bore. In this way, the same sized fastener or spark plug that was installed originally within the metal casting can be used after the repair. Besides fasteners and spark plugs, the insert also finds utility, inter alia, for repairing hydraulic fitting threads, pipe threads and as a blind hole insert. 
     Moreover, the instant invention addresses and resolves any problems associated with an attempt to subsequently remove the fastener or spark plug after the repair. In some situations, typically harsh operating environments involving corrosion or galvanic attraction between the various components of a system, the mating area between the threads of the fastener or spark plug can become seized to the insert. When this occurs, an attempt to remove the fastener or spark plug can sometimes cause rotation of the insert in conjunction with the fastener or spark plug, thwarting removal of the fastener or the spark plug alone. The probability of this occurring according to the present invention is substantially nil. The solution preferably includes the utilization of both specially formed threads and a shoulder on the insert which is adapted to provide a cylindrical bore strategically located to vertically align with the meshing exterior threads of the insert and the threads formed in the bore of the material being worked on. A top surface of the insert&#39;s shoulder includes a cylindrical bore. After the insert has been placed within the material to be repaired, a hole may be drilled extending the cylindrical bore into the juncture of the exterior threads of the insert and the threads of the bore in the material. Finally, a cylindrical pin is driven into the cylindrical bore through the shoulder and into the drilled area of the exterior threads of the insert and the threads of the bore of the material so that the insert will no longer readily move with respect to the material because the flight of the threads of the insert on an exterior surface thereof will be opposed by the placement of the cylindrical pin and its retention by the threads of the bore of the material. 
     Where the insert already includes a vertical channel defining a thread gap aligned with the cylindrical bore of the insert&#39;s shoulder, the drilling step is not mandatory. In this case, driving the cylindrical pin will actually improve insert retention because the threads in the bore contacted by the pin distort and therefore enhance retention of the insert in the bore. 
     OBJECTS OF THE INVENTION 
     Accordingly, a primary object of the present invention is to provide a threaded insert which resists removal once installed in a repair. 
     A further object of the present invention is to provide an insert which is not necessarily used in a repair, but instead provides a material of a different characteristic than the surrounding material within which it is threaded which resists dislodgment once installed. For example, the instant invention can be a relatively hard steel threaded into a relatively soft material such as aluminum to provide superior gripping and a more beneficial characteristic with the fastener or spark plug located within the interior threads of the insert. 
     A further object of the present invention is to provide a device as characterized above which is easy to install, difficult to remove and durable in construction. 
     A further object of the present invention is to provide a device as characterized above which is economical to manufacture and provides an economical solution to repairing objects which heretofore had to be discharged as unrepairable. 
     A further object of the present invention is to provide a device as characterized above which allows a fastener or spark plug of original dimension to be reinstalled in a bore after repair. 
     A further object of the present invention is to provide a device as characterized above which can be used with other fittings, such as hydraulic or pipe fittings and in blind bores. 
     A further object of the present invention is to provide a method for repairing or fabricating a receiving area for fasteners or spark plugs which includes the steps of providing a thread within a bore to receive. the insert, installing the insert into the threaded, bore, fixing the insert into the bore to preclude further rotation, and installing a fastener or spark plug in the bore. 
     Viewed from a first vantage point, it is an, object of the present invention to provide an insert, comprising, in combination: a sleeve, an exterior thread formed on the sleeve, an interior thread formed in the sleeve, a shoulder on one end of the sleeve, a bore in the shoulder axially aligned with the exterior thread, and a pin passing through the bore. 
     Viewed from a second vantage point, it is an object of the present invention to provide a method for repairing or fabricating a receiving area for an object, the steps including: providing a thread within a bore to receive an insert, threading the insert into the threaded bore, fixing the insert into the bore to preclude further rotation of the insert, and installing the object in the insert. 
     Viewed from a third vantage point, it is an object of the present invention to provide a device for providing a lining in an object, comprising, in combination: a sleeve having an exterior diameter substantially complemental to a bore in the object to be lined, a peripheral shoulder emanating from one end of the sleeve, a pin dimensioned to lodge in the shoulder and along an interface between the sleeve and the bore. 
     Viewed from a fourth vantage point, it is an object of the present invention to provide a sleeve having an interior thread and an exterior thread, the exterior thread includes a vertically aligned clearance to receive a pin therewithin. 
     Viewed from a fifth vantage point, it is an object of the present invention to provide a n insert, comprising, in combination: a sleeve having interior and exterior threads, a shoulder on one end of the sleeve having a hole passing therethrough, clearance in the exterior threads aligned with the hole, and a pin dimensioned to pass through the hole and reside within the clearance. 
     These and other objects will be made manifest when considering the following detailed specification when taken in conjunction with the appended drawing Figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the apparatus according to the present invention in its environment. 
     FIG. 2 is a side view of the apparatus according to the present invention. 
     FIG. 3 is a view similar to FIG. 2 showing the interior of the apparatus according to the present invention. 
     FIG. 4 shows the apparatus according to the present invention during one stage of deployment. 
     FIG. 5 depicts one operative characteristic of the present invention. 
     FIG. 6 shows the FIG. 5 view in a different vantage point. 
     FIG. 7 shows an alignment instrumentality for providing a cylindrical bore for the apparatus according to the present invention. 
     FIGS. 8A and 8B show the insert used in hydraulic fitting thread repair. 
     FIGS. 9A and 9B show the insert used in spark plug thread repair. 
     FIGS. 10A and 10B show the insert used as a blind hole insert. 
     FIGS. 11A and 11B show the insert used in a pipe thread repair. 
     FIG. 12 shows a preferred geometry to cause a seal of the insert once installed by encouraging material deformation and flow. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Considering the drawings, wherein like reference numerals denote like parts throughout the various drawing FIGS. , reference numeral  10  is directed to the thread repair insert according to the present invention. 
     In essence, and referring to FIGS. 1 through 3, the thread repair insert  10  includes an optional drive head  20  at an uppermost portion thereof, a neck  30  below the drive head  20 , a shoulder  40  below the neck  30  and a sleeve  60  extending below the shoulder  40 . If there is no drive head  20 , there is no need for neck  30 . The sleeve  60  includes an exterior threaded portion  62  which extends from an upper portion  64  to a bottom portion  66 . The exterior threaded portion  62  includes a plurality of threads  68  thereon which include an upper surface  72  and a lower surface  74  which extend upward toward the head  20  from a minor diameter  69  to a major diameter  70 . Thus, a crest  76  of each thread  68  is closer to the head  20  than a portion of the thread  68  between adjacent roots  82  at the minor diameter  69 . 
     The thread repair insert  10  further includes an interior bore  100  extending from a first end  102  to a second end  104 . A chamfer  106  is provided on a top surface  22  of the head  20  and provides a transition area between the top surface  22  of the head  20  and the first end  102  of the interior bore  100 . Preferably, the interior bore  100  includes a cylindrical side wall  110  which extends between the first end  102  of the interior bore  100  to an area adjacent a top surface  42  of the shoulder  40 . The interior bore  100  then transitions to an in-taper  112  which preferably tapers inwardly from the area adjacent the top surface  42  of the shoulder  40  to a start of interior threads  114 . The interior threads  114  preferably extend from in-taper  112  to the second end  104  of the interior bore  100 . Preferably, the interior threads  114  are of a common type which include an inner diameter  116  and an outer diameter  118 . Each thread includes an upper side  120  and a lower side  122 . 
     The neck  30  includes a crease or break-off groove  32  which fractures, shearing the head  20  off of the thread repair insert  10  before a magnitude of torque applied to the insert  10  reaches a maximum torque allowed to be applied to the exterior threads  68 . Thus, the head  20  shears off at the break-off groove  32  prior to torsionally over stressing the exterior threads  68 . Head  22  is then discarded. 
     Once the head  22  has been removed at the break off groove  32 , the top surface  42  of shoulder  40  is clearly exposed. Please see FIGS. 4 through 6. As shown in FIG. 4, the insert  10  is embedded into the threaded bore of the material M. Removal of the head  22  exposes an area on the top surface  42  that reveals an elongate cylindrical hole  43  (variation  1 ) passing through the shoulder  40  parallel to but offset from the longitudinal center line  12  of the insert. This cylindrical hole  43  is strategically oriented to pass through a downslope  54  (FIG. 3) which defines a transition from the shoulder  40  to the exterior threads  62  inboard of an upslope  52  of cusp  50 . In lieu of a cylindrical hole  43 , an imprint  45  (variation  2 ) may appear on the top surface  42  of shoulder  40  to indicate an area for drilling the cylindrical hole  43 . A third variation for locating a hole  43  involves using a peripheral flange  175 . Please see FIG.  7 . The peripheral flange is provided with at least one guide hole  173  passing through its flange  175  to serve as a support for drilling the hole  43 . A stem  177  temporarily locates within the interior threads  114  of the bore  100  to assist in drilling hole  43 . In all cases, while one hole and pin is shown, more than one could be deployed. 
     In any event, once the orientation of FIG. 4 has been achieved and whether the cylindrical hole has been preprovided or must now be provided, it is still desired that a drill pass into the intermeshing threads of both the insert  10  and threads formed on the material M. Once a cylindrical bore has been provided which removes one vertically stacked array of threads underlying the cylindrical bore  43  for both the insert and its host within which it is threaded, a cylindrical pin  47  is driven into the cylindrical hole  43  and into the hole formed between the threads of the insert and the material. The cylindrical pin  47  is quite effective in preventing any unwanted migration of the insert  10  at a future date. Note that because the cylindrical bore  43  and its subsequent penetration into the intermeshing threads is radially offset from the longitudinal axis  12  of the insert  10 , a barrier has been provided to preclude further rotation in any direction of the insert relative to the material within which it is threaded. This feature is of considerable significance given the likelihood that once the threaded fastener  150  is lodged within the interior threads of the repair insert  10 , subsequent removal of the threaded fastener  150  can occur with nearly total surety that the insert  10  will not become dislodged from its environment. 
     More specifically, and referring in detail to FIGS. 1 through 3, the thread repair insert  10  are shown in detail. The thread repair insert  10  includes the optional head  20  at an uppermost end thereof. The head  20  preferably includes multiple facets  24  arranged to allow a torque applying device to effectively engage the head  20 . Preferably, the facets  24  are arranged in a hexagonal pattern to be engaged by a variety of commonly available torque applying tools. Alternatively, various other facet arrangements could be utilized or slots could be provided in the top surface  22  of the head  20  for receiving a screwdriver or other similarly shaped tool. In addition, an internal hex head may be formed on an internal sidewall  110  of the head  20  (FIG.  3 ). The head  20  is preferably radially symmetrical about a central axis  12  which passes through the thread repair insert  10 . 
     The neck  30  joins the head  20  to the shoulder  40 . The neck  30  is preferably arranged as a single frustum with a greater diameter base  34  adjacent the head  20  and a lesser diameter crease or break-off groove  32  adjacent the shoulder  40 . The break-off groove  32  and base  34  thus define parallel planes of the frustum of the neck  30 . The break-off groove  32  is preferably designed to have a cross-sectional area which is less than a cross-sectional area of almost any other portion of the thread repair insert  10 . Thus, when torsional loads increase, the thread repair insert  10  is most likely to fracture at the break-off groove  32  than at any other location along the thread repair insert  10 . 
     In addition, the break-off groove  32  is preferably provided with a cross-sectional area which gives the break-off groove  32  a maximum torsional load characteristic which is less than a torsional load necessary to cause damage to the exterior threads  68  of the exterior threaded portion  62  of the sleeve  60 . In this way, if torsional loads on the thread repair insert  10  begin to approach a level which may cause damage to the exterior threads  68  of the exterior threaded portion  62 , the break-off groove  32  of the neck  30  will fracture before a damaging torsional load is reached which will damage the threads  68 . 
     The shoulder  40  is interposed substantially between the neck  30  and the sleeve  60 . The shoulder  40  includes a top surface  42 , a cylindrical side portion  44  and a cusp  50  exposed at a lowermost portion of the shoulder  40 . The top surface  42  of the shoulder  40  is adjacent the break-off groove  32  and transitions into the cylindrical side portion  44 . The cusp  50  is located at the lowermost portion of the shoulder  40  and includes an upslope  52  which preferably diverges inwardly and upwardly toward the central axis  12  and then transitions into a downslope  54  which preferably diverges inwardly and downwardly toward the central axis  12 . The downslope  54  of the cusp  50  transitions into the top  64  of the exterior threaded portion  62  in which the helically wound exterior threads  68  terminate. 
     The exterior threaded portion  62  of the sleeve  60  is of a substantially cylindrical construct which extends from a location adjacent the downslope  54  of the cusp  50  of the shoulder  40  to the bottom  66  of the sleeve  60 . The bottom  66  of the sleeve  60  defines an opposite end of the thread repair insert  10  from the head  20 . The exterior threaded portion  62  is oriented about the central axis  12  with the central axis  12  passing through a geometric center of the sleeve  60 . The sleeve  60  has the exterior threads  68  formed about the cylindrical surface thereof. 
     The exterior threads  68  are preferably one continuous helically wound thread which begins at the bottom  66  and spirals up to a top  64 . While this single thread design is preferred, other arrangements including a compound series of threads which wind helically together from the bottom  66  to the top  64  could also be utilized. 
     Referring to FIG. 2, the exterior threads  68  include the crest  76  defining the major diameter  70  of the exterior threads  68 . The exterior threads  68  have an upper surface  72  which extends from a bottom edge  86  of a root  82  to an upper edge  78  of the crest  76 . The exterior threads  68  also include a lower surface  74  which extends from a top edge  84  of the root  82  to a lower edge  80  of the crest  76 . Both the upper surface  72  and the lower surface  74  angle upward toward the head  20  as the surfaces  72 ,  74  extend from the root  82  to the crest  76 . Both the crest  76  and the root  82  exhibit a substantially constant distance from the central axis  12  between the upper edge  78  and the lower edge  80  and between the top edge  84  and the bottom edge  86 . 
     In section, the surfaces  72 ,  74  extend linearly from the root  82  to the crest  76 . However, as this contour is rotated helically about the sleeve  60  along with the threads  68 , the upper surface  72  and lower surface  74  take on a curved surface appearance. This appearance is similar to that which would be formed by a linear section of the surface of a cone with a tip of the cone oriented downward and the cone rotated and translated upward along a central axis thereof. The upper surface  72  and the lower surface  74  thus have a curved surface in three dimensions similar to that of a cone, but a linear character when viewed in section. 
     The upper surface  72  extends from the root  82  to the crest  76  at an upper surface angle α diverging from a reference plane  14  orthogonal to the central axis  12 . The upper surface angle α is preferably approximately 20° degrees but could be any angle between 0° degrees and 90° degrees. The lower surface  74  extends from the root  82  to the crest  76  at a lower surface angle β with respect to the reference plane  14 . The lower surface angle β is preferably approximately 40° 0  degrees but could also vary between 0° degrees and 90° degrees. 
     Preferably, the upper surface angle α is less than the lower surface angle β such that a thickness of the exterior thread  68  at the crest  76  is less than a thickness of the threads  68  between adjacent roots  82 . In this way, the threads  68  are provided with greater thickness, and hence greater strength, adjacent the minor diameter  69  than at the major diameter  70  and are thus more capable of bearing the loads experienced within the threaded hole H. One advantage of having ox less than e is that once the insert bottoms out in a blind bore or once the cusp  50  (at the circle where upslope  52  and side portion  44  join) bites into floor  274  (or surface S if no counter bore), the threads of the insert  10  force the threads of the bore radially inward, which is especially useful in crack repair. This also prevents “upheaval” of material M about a crack. Alternatively, both angles could be parallel to provide similar benefits. 
     As mentioned, the thread repair insert  10  further includes an interior bore  100  having a first end  102  and a second end  104 . Chamfer  106  is provided on the top surface  22  of the head  20  and transitions therefrom to the first end  102  of the interior bore  100 . The interior bore  100  then transitions from the first end  102  to taper  112  via a cylindrical sidewall  110 . The taper  112  transitions from a greater diameter adjacent the break-off groove  32  of the neck  30  to a lesser diameter adjacent an interior threaded portion which extends from in-taper  112  to the second end  104 . The interior threaded portion includes interior threads  114  disposed thereon. The interior threads  114  are preferably of a conventional type and include an inner diameter  116  and an outer diameter  118 . In addition, the interior threads  114  are provided with an upper side  120  and a lower side  122 . 
     In use and operation, the first step in repairing a standard threaded hole H is to prepare it for receiving the thread repair insert  10 . This is accomplished by removing or drilling out the previous standard threaded fastener which may still be retained within the threaded hole H. Once the standard threaded fastener has been removed or a hole H is provided, a tapping bit is preferably used to form the threads of the hole H complemental to the threads described in conjunction with FIG.  2 . 
     Preferably, the threaded hole H includes the counter bore formed at a transition area between the hole H and the surface S of the material M. The counter bore preferably includes a cylindrical side portion  276  dimensioned similarly to the cylindrical side surface  44  of the shoulder  40 . The cylindrical side portion  276  of the counter bore extends from the surface S down to a floor  274  which is preferably cusped. The floor  274  may substantially complement the geometry of the cusp  50  at upslope  52  of the shoulder  40 . If upslope  52  and floor  274  are not mutually parallel, metal deformation can occur at the interface, with the softer of the two metals (i.e., the threaded insert  10  or the material M) “flowing” (deforming) into the available space providing a tighter seal. 
     FIG. 12 provides a sectional close-up of the metal “flow” (deformation) geometry  200 . Upslope  52  is shown as preferably having an included angle γ of 45°. Upslope thereafter transitions to a constant radius curved recess  202  which becomes filled with flowing metal FM (e.g. FIGS. 8B,  9 B,  10 B,  11 B) which typically will come from the area  200  in general and from floor  274  “curling” up into the recess  202  in a preferred, particular manner. The preferred angle Δ between side portion  276  and floor  274  is 30°, but as with γ can vary. It is merely preferred that γ&gt;Δ. The “curling” occurs as the insert is being lodged into the material M. Recess  202  includes downslope  54 ″ which transitions to annulus  55  leading to thread top  64 . 
     After the threads T are formed within the threaded hole H and the counter bore has been formed, the thread repair insert  10  is disposed within the threaded hole H. The thread repair insert  10  is disposed within the threaded hole H by applying torque to the drive head  20  causing rotation of the thread repair insert  10  about arrow F (FIG.  1 ). This rotation causes the upper surface  72  of the exterior threads  68  to slide along the complementally formed threads T of the hole H. 
     Rotation continues about arrow F until the shoulder  40  abuts against the floor  274  of the counter bore and thus providing a clamping effect (and as mentioned sometimes metal flow or deformation). Once sufficient torque is applied that the neck  30  can no longer resist deformation, the head  20  is severed therefrom at the break-off groove  32 . In some instances, no head  20  is provided. 
     For example, assume FIGS. 4 and 5 display an article of manufacture, as is, without the head. A bolt threaded into the interior, central core of the insert (such as bolt  150  of FIG. 1) can be used to drive the insert into the material M once the bolt is constrained from rotating within the insert&#39;s central threaded core. For, example, the bolt head can abut the top surface  42  of the insert or one of two adjacent nuts threaded onto bolt  150  can abut surface  42  to advance the insert. 
     While it has been mentioned that the cylindrical locking pin  47  is inserted only after a drill plunges between engaging threads of the bore and insert, it is contemplated that vertically aligned thread portions from the insert  10  could be previously removed (during manufacturing) allowing clearance  49  (FIG. 5) for pin  47  without requiring thread removal from the insert during installation. In actuality, the clearance  49  can be regarded as an interruption of the thread in an area vertically aligned with hole.  43 . The clearance length plus the shoulder thickness preferably equals the length of the pin  47 . Drilling threads in the bore is not mandatory. Driving the pin into bore  43  will then deform the thread of the material M around the clearance  49  providing even more interference, sealing and resistance from removal. 
     FIGS. 8A and 8B exemplify the headless insert  10  used as a repair for hydraulic fittings HF, which typically use a gasket G. In this embodiment the metal flow FM mentioned with respect to the cusp geometry vis-à-vis the counter bore is mandatory to assume a high pressure seal. 
     FIGS. 9A and 9B also exemplify the need for metal flow F in the environment of spark plug thread repair. The preferred material for the spark plug insert is hard anodized aluminum, particularly for use with now prevalent aluminum cylinder heads. Hard anodizing thwarts the spark plug from seizing, sticking, bonding or galvanizing to the insert for ease in subsequent removal as in a tune-up. 
     FIGS. 10A and 10B embody an alternative insert  10 ″ provided with a bottom wall  101  which in conjunction with metal flow FM can be used to seal off an existing hole or repair a crack where the material M is in actuality a housing whose interior needs to remain sealed closed. 
     FIGS. 11A and 11B illustrate an insert used with a pipe thread in which metal flow FM is desired since the pipe plug P (or pipe conduit) requires that the juncture around the insert is fluid impervious. 
     Moreover, having thus described the invention, it should be apparent that numerous structural modifications and adaptations may be resorted to without departing from the scope and fair meaning of the instant invention as set forth hereinabove and as described hereinbelow by the claims.