Fastening device for locking an insert in a hole of a support member

A device for locking an insert in a support having a receiving hole or sealing a tubular member such as a pipe, consists of a somewhat bottle-shaped bushing having a cylindrical collar or bushing portion, and a conical portion secured at its narrow end to said collar, an inside screw thread, and a locking ring seated on the cone adjacent to the collar. The dimensions of the collar section of the bushing, the cone and the locking ring are so correlated that bushing and locking ring fit the cross-section of the hole with slight friction when the insert is placed in the hole. Locking of the insert in the hole is effected by inserting a screw bolt or screw tightening means into the insert coaxial therewith. This causes lifting of the insert which in turn effects spreading of the locking ring thereby pressing the same against the wall of the hole. The depth to which the insert is inserted into its hole provides means for accurately regulating the degree of force applied by the expanding insert on the surrounding hole wall.

The present invention relates to a device for attaching two members to each 
other, and more particularly, to a device for fastening a structural 
member such as a panel or other component such as carrier to a support 
member including a receiving hole. 
BACKGROUND 
A frequent application for insert-type fastening devices generally known as 
"Thread-Inserts" is the utilization of holes in the corner or side fillets 
or projecting mounting studs of molded or die-cast boxes or containers to 
which a lid or panel or a component part is to be affixed. This is the 
most common way of mounting and assembling appliances and instruments. The 
use of such thread inserts is very widespread in industrial production. 
Therefore, cost of the inserts and economy of insertion are of 
considerable importance. For example, the obvious methods of drilling and 
tapping the fillets or insert-molding thread bushings into the case, are 
by far too slow and expensive. They are hardly used nowadays in 
production. 
According to the state of the art now known, thread inserts are commonly 
small metal bushings with an inside thread and a rough outside; generally, 
the bushings are knurled or grooved, or have sharp undercuts. They are 
frequently slotted in axial directions, so that the inserted screw may 
produce a slight expansion, or they may rely for anchoring on a springy 
circumferential component which has to be compressed for insertion and 
bears frictionally against the hole wall. It is characteristic of most 
known types of thread inserts that they must be force-fitted into the 
holes in the container or mounting base. This force-fitting characteristic 
applied also to those types of known thread inserts which have on their 
outside a coarse self-cutting thread so that they can be forcibly screwed 
into the holes in the mounting base. As a result, it occurs not 
infrequently that the force of the insertion cracks the plastic or 
die-cast mounting base, or sets up tensions and stresses which later 
result in cracks. If the insertion is less forcible, the insert may remain 
loose or may be subsequently loosened by vibration or may turn when a 
screw is inserted and tightened. The different expansion coefficients of 
the metal bushing and the surrounding plastic or die-cast material may 
also lead to loosening at a later date, especially under the influence of 
vibration. 
In order to overcome the problems caused by forcible insertion of thread 
inserts, ultrasonic or spot-heating devices are used to insert the bushing 
into the hole without the use of force, by locally plasticizing or 
re-heating the material surrounding the bushing. Spot-heating devices are 
restricted to use on thermoplastic materials. They are comparatively slow 
to operate, and they are not always fully reliable in use if there is a 
variation in conditions (tolerance of the bushing diameter or of the hole 
diameter, or of the chemical composition of the plastic). 
Another known type of the thread insert which does not require forcible 
installation, consists of a coil of wire of lozenge-shaped cross-section. 
This wire coil is screwed into a hole in the mounting base which has 
previously been tapped. It offers advantages through the elasticity of the 
wire coil which forms the screw thread but is obviously not used for the 
same purpose nor is it economically competitive with inserts whose 
principal purpose is to save the tapping operation. 
THE INVENTION 
It is a broad object of the invention to provide a novel and improved 
fastening device for fastening a structure to a support member including a 
mounting hole, by "push-fitting" an insert into the mounting hole and then 
screwing a screw into the threaded insert hole thereby automatically 
tightening and locking the insert in the mounting hole and simultaneously 
securing a lid or other structure to the support member. "Push-fitting" is 
herein defined as sufficient to hold the insert lightly and temporarily in 
place pending the tightening of the screw, as opposed to "force-fitting" 
which furnishes all or most of the anchorage for the insert. 
Another object of the invention is to provide a novel and improved 
fastening device in which a locking ring initially positioned and shaped 
to permit insertion of the insert of the fastening device into the 
mounting hole of the support member is automatically changed into a 
position and shape causing locking of the insert within the mounting hole 
upon tightening a screw for fastening a structure to the support member. 
A more specific object of the invention is to provide a novel and improved 
fastening device including means facilitating insertion of the insert into 
the mounting hole to a depth permitting precise control of the expansion 
force exercised by the insert against the wall of the mounting hole in the 
support member upon tightening of the mounting screw. 
Another specific object of the invention is to provide a novel and improved 
fastening device including means to strengthen the locking of the screw 
inside the insert (vibration-proofing) by collapsing, through pressure 
against the panel or other component secured by the screw, part of the 
bushing upon lifting of the insert in response to tightening of the screw 
and pressing said collapsed part against and in-between the threads of the 
screw. 
Another more specific object of the invention is to provide a novel and 
improved fastening device including a compressible member by which the 
thread insert is sealed to the screw and the wall of the mounting hole, 
upon lifting of the insert in response to tightening of the screw. 
A further specific object of the invention is to provide a novel and 
improved fastening device which will enable a screw to be fitted 
instantaneously to a threaded hole in any type of rigid material the 
thread of which has been worn out or damaged. 
Another specific object of the invention is to provide a quick-acting 
closure for pipes carrying liquids or gases under pressure. 
SUMMARY OF THE INVENTION 
The afore-pointed out objects, features and advantages, and other objects, 
features and advantages which will be pointed out hereinafter and are set 
forth in the appended claims are obtained by providing an insert member 
insertable into a cylindrical receiving hole in the support member to 
which a panel or other part is to be fastened. This insert member 
comprises a bushing portion of circular outline which fits the diameter of 
the receiving hole with light friction which may be obtained by roughening 
or knurling the outside surface of the cylindrical portion of the bushing. 
A conical portion is secured with its narrow end to the collar portion of 
the bushing or is integral therewith. The cone is coaxial with the bushing 
and its outer maximal width fits the diameter of the receiving hole. A 
locking ring or band made of a resilient and bendable material such as, 
for instance, steel, iron, copper, brass, or synthetic plastics material, 
for instance polyethylene or polyvinyl chloride, is fitted upon the cone. 
It has an inner diameter such that it is loosely retained in a position on 
the cone adjacent to the collar of the bushing. Its outer diameter is 
slightly larger than that of the receiving hole so that the locking ring 
is slightly compressed by insertion of the device into the receiving hole. 
The loose fit of the ring and the gap in its circumference afford enough 
clearance for the ring to be thus compressed. 
It is also possible to use for the locking ring a non-resilient but 
deformable material such as a lead or a die-casting alloy or even rubber. 
In this instance, the locking ring need not be split and need not be 
fitted loosely as described above because it is slightly squeezed and 
deformed during insertion into the mounting hole. Once inserted both types 
of locking rings perform identically. This type of insert is especially 
useful for inserts which are used to pressure-seal liquids and gases. 
A threaded hole extends, partly or entirely, through the axis of the insert 
to receive a screw. 
To secure a part such as a panel to a support member such as a box having 
mounting holes, the insert is pushed, with the conical portion first, into 
one hole, slightly below the level of its edge. The aforedescribed 
correlation of the outer dimension of the bushing, the reversed cone, and 
the ring with the diameter of the mounting hole permits such insertion 
without difficulty either manually or by automated equipment, but provides 
sufficient friction between the hole wall and the locking ring and between 
the hole wall and the bushing, respectively, to hold the insert axially in 
place and to thread the screw into the insert without free turning of the 
insert. 
The panel is placed upon the box with a suitable hole in the panel in 
registry with the threaded hole in the insert and the screw is now screwed 
through the panel into the insert. As the screw is tightened, it 
automatically lifts the entire insert relative to the mounting hole in the 
box and relative to the locking ring. Such lifting forces the conical part 
of the bushing deeper into the locking ring. As a result, the locking ring 
is expanded and its outside is pressed with increasing force against the 
wall of the mounting hole thereby locking the insert within the mounting 
hole and thus fastening the panel safely to the box. 
The inserts according to the invention will operate equally well in a 
smooth-walled hole or in a hole which has previously been threaded. The 
configuration or the state of preservation of the thread is quite 
immaterial. 
Thread inserts according to the invention can be used repeatedly. When the 
screw is removed, the above-described friction between bushing, locking 
ring and hole wall will hold the insert in place. An insert can be 
removed, if desired, by pushing it downwards into the hole whereby the 
cone section of the bushing ceases to expand the locking ring and thereby 
loosens the anchorage of the insert. 
The inserts according to the invention can be supplied to the user in 
pre-assembled form with the locking ring in position as described, or in 
two separate parts which are assembled automatically during the process of 
inserting the fastener into its mounting hole. 
The slight lifting movement of the insert during the tightening of the 
screw which has been described above, is a very essential part of the 
invention, and so is its utilization for the purpose of controlling and 
limiting the expansion force exercised by the insert against the wall of 
the mounting hole. The aforesaid lifting movement is further utilized for 
collapsing a vibration-proofing collar against the tightened screw, or of 
pressure-sealing the insert. 
Likewise typical is the fact that the anchoring force of the insert is 
essentially represented by compression of the locking ring or band. This 
anchoring force is applied uniformly and evenly in a (near) circle, and it 
increases proportionately to the fastening torque applied by the screw, or 
to a removal force applied to the fastened panel or component. The 
last-mentioned feature constitutes the "automatic servo-action of the 
reversed-cone lock" and is so potent that means for its control are 
advisable when the insert is used in thin-walled material. Control of the 
tightening torque is provided automatically by regulating the insertion 
depth of the bushing.

DETAILED DESCRIPTION OF THE DRAWING FIGURES 
Referring now to the drawing figures more in detail, and first to FIG. 1, 
the left half of this figure shows an embodiment of the insert according 
to the invention inserted into a suitably dimensioned bore in a body made 
of form-retaining material, such as synthetic plastic material or metal. 
The insert is pushed into the bore without the use of force. Contrary to 
other inserts of this type, it locks when the screw is tightened, and its 
locking strength increases in proportion to the applied load. 
More specifically the insert according to FIG. 1 comprises a bushing 1 made 
for instance of metal or a hard synthetic plastics material. The inside of 
the bushing is threaded with a female thread 2 and the outside at its 
largest diameter, hereinafter called collar 2a, is preferably roughened 
for instance by grooves or knurls. A cone 3 extends from one side of the 
collar facing the same with its narrow end. The wide end of the cone has 
preferably an inwardly tapered portion 4 to facilitate insertion of the 
bushing into a hole. The insert further comprises a split locking ring 5. 
The ring is made of metal, and its dimensions and hardness are selected in 
correlation with the dimensions of the cone and the inner peripheral 
outline of the bore and its material as will be hereinafter explained with 
reference to FIG. 1. The ring may have a triangular cross-section as is 
shown in FIG. 1. Ring 5 may have a round, rectangular or similar 
cross-section and be grooved to roughen its outer surface. 
FIG. 1, shows a portion of a body, such as a box 6, made of synthetic 
plastics material or other suitable material to which a part such as a lid 
or panel 7 is to be fastened by means of one or several inserts as above 
described. To effect such fastening of the panel, bores 8 are provided in 
the sidewalls of box 6, or in corner or sidewall fillets or in studs which 
form part of the box. The diameter of each bore is such that it just fits 
the outer diameter of the collar part 2a of the bushing 1. 
The insert is then pushed into the bore to such a depth that the top level 
of the bushing is somewhat below the top surface of box 6. The insert is 
held in its position in the bore by knurled collar 2a and by locking ring 
5 which is slightly compressed during insertion of the insert. 
Fastening of the panel is effected by inserting screw bolts 9 through the 
panel and screwing them into the bushings. The knurled or otherwise 
roughened collar 2a of the bushing provides friction between the bushing 
and the wall of the bore 8 sufficient to permit the initial screwing-in of 
screws 9 without spinning or idling of the insert. The now expanding 
locking ring 5 holds the insert in its depth position in the bore. This 
preliminary stage of holding the insert in bore 8, securing it against 
spinning and against depth displacement, and fastening the panel, is shown 
in the left half of FIG. 1. 
Referring now to the right half of FIG. 1, this figure shows screw bolt 9 
fully screwed in, thereby locking the insert within the bore and pressing 
the panel against the box. 
According to the invention, continued screwing-in of the screw 
automatically effects tightening of the insert in the bore. As is shown on 
the left side of FIG. 1, initially locking ring 5 is located at or close 
to the narrow end of the cone and is slightly compressed during the 
insertion of the insert. As the screw is being screwed in, the bushing is 
pulled towards the head of the screw. As the locking ring 5 is held 
stationary by its friction against the bore wall, it expands more and more 
as it is wedged open by an increasingly wider portion of the cone. As the 
insert moves upwards, the ring is squeezed stronger and stronger between 
bore wall and bushing. This locking action is hereinafter referred to as 
"Reversed Cone Lock". It is typical for this locking action that the 
locking strength of the insert increases proportional to the applied screw 
pressure. 
The right half of FIG. 1 shows the screw fully screwed-in, it also shows 
the locking ring in its locking position and the entire insert lifted 
upwards relative to the position shown in the left half of FIG. 1. The 
division of FIG. 1 in two halves shows clearly the relative movement of 
the various components which coact in the locking action. 
FIGS. 2A to 2D show five different types of locking rings and several types 
of cones. This enumeration is not exhaustive but will serve to illustrate 
the design principles guiding the choice of the locking ring 5a and the 
cone. Type A is a split ring made from wire, as it is loosely fitted on 
the cone just below the collar 2a, and as it projects slightly from the 
profile of the collar, it is compressed as soon as the insert is pushed 
into the bore the diameter of which is indicated by two parallel lines. 
This type of locking ring is inexpensive to manufacture. It makes contact 
with the cone surface only along the narrow line of its inner diameter, 
and this friction may not always be enough to anchor the ring securely 
against the pull of the upwards-moving bushing. 
FIG. 2B shows a locking ring 5a made from thin wire, coacting with a longer 
cone. This increases friction but makes the fastener more dependent on the 
tolerance of the bore into which it is to be inserted. If there is too 
much clearance or if the base material is too soft, the locking ring may 
pull out under load. 
FIG. 2B shows a locking ring 5 made from sheet metal which has a number of 
sharp-edged punched holes which increase friction. 
FIG. 2D shows a locking ring 5d made from wire with wedge-shaped 
cross-section the outside of which is preferably roughened. The projecting 
upper edge of the ring presses sharply against the wall of the bore when 
the fastener is inserted. When the ring is compressed its triangular 
cross-section conforms essentially with the shape of the cavity between 
cone and hole wall into which the locking ring is wedged. The embodiments 
shown in FIGS. 2D and 2C are the locking rings for all-round performance 
in different materials, combined with short overall length of the cone 
part of the bushing. 
FIG. 2C shows a locking ring 5C which has no gap and is not loosely but 
tightly fitted around the root of the cone. It has a preferably triangular 
cross-section, with the apex projecting over the diameter of the bore. 
This locking ring is made from lead or die-casting metal or even from 
rubber or plastic and is capable of being deformed by pressure. When ring 
5C is inserted into a hole with some degree of force, the projecting apex 
line of the ring is flattened and bears frictionally against the hole 
wall. The deformation of the ring material permits it to act in like 
manner as the split locking rings described above. It also has the effect 
of wedging the pliable lead tightly between cone and hole wall, and as 
there is no gap in the ring, establishing a seal capable of withstanding 
high pressure of liquids or gases. If the insert is used for this purpose, 
its axial bore does not extend for the full length of the bushing. 
FIG. 2D also shows roughening of the cone portion of the bushing by 
knurling or otherwise impressing a pattern upon the cone. This increases 
the friction between cone and locking ring 5d. 
All locking rings shown in FIGS. 2A through FIG. 2D have in common that 
their diameter at the lower edge is slightly smaller than the diameter of 
the hole and permits initial entry of the insert into the hole, and that 
on continuing insertion the ring is compressed inside the hole and bears 
frictionally against the hole wall. 
The selection and design of a suitable type of cone and locking ring is a 
matter of balancing the axial pull of the screw 9 against the friction 
exercised by the locking ring against the hole wall. If these two factors 
are not correctly balanced, having regard to the material, and the 
diameter tolerances of the bore as well as to the angle, surface and 
length of the cone, the locking ring will not remain stationary as shown 
in FIG. 1, but will move upwards. Incorrectly balanced fasteners will hold 
a panel by simple friction in the holes but will fail to develop the 
"Reversed Cone Lock" action which is the essence of the fastening devices 
according to this invention. 
The initial placement of the insert below the level of the box is essential 
for the functioning of the insert. There is no fixed maximal depth but the 
minimal depth should be so that the insert on its upward travel does not 
yet touch the panel. FIG. 1 shows both positions of the insert. If 
inserted in this manner that is to say with excess space for upwards 
travel, the insert is able to develop its full locking strength which 
increases in proportion to the torque applied by means of the screw or to 
the tensile pull applied to the fastened panel. This vast reservoir of 
locking strength is desirable in some applications such as for instance 
when the insert is embedded in metal. However, if the insert is to be 
embedded in a thin-walled section of plastic material such as a stud or 
fillet, the expansion and locking capacity of the insert may result in 
cracking the plastic. This can be avoided by limiting the torque of the 
screws holding a panel, by means of a torque screwdriver. Such 
screwdrivers are readily available for the production assembly of a 
manufactured unit but will not always be at hand when an installed panel 
is removed for access and subsequently refastened. 
However, the insert has its own built-in means for limiting torque and 
expansion during the installation. This is achieved by controlling the 
insertion depth of the insert in such a manner that the collar 2a touches 
the panel 7 when the desired maximum expansion of the locking ring is 
reached. As soon as the insert collar touches the panel, all expansion 
action stops. This relation of the insertion depth to the limitation of 
expansion is clearly shown in both halves of FIG. 3 which shows the insert 
of FIG. 1 in its locking position. 
FIGS. 4A, 4B and 4C shows some practical means according to the invention 
to control the insertion depth of inserts embedded in holes in a plastic 
body 6 as described hereinbefore. There is shown in each of the three 
Figures a shaped handle 15, 16 and 17 respectively which abuts against the 
edge of the respective hole when a plug 15a, 15b and 15c respectively 
pushes the insert down into the bore. 
The handle of FIG. 4A pushes the insert deep enough for unlimited 
tightening torque and expansion. 
The handle of FIG. 4B limits the insert to optimal torque and expansion 
without danger of cracking the plastic. Both tools are inexpensive plastic 
moldings which can be used as tools for hand inserted inserts or as 
gauges. 
FIG. 4C shows a tool suitable for production runs in which the insertion 
depth and thereby the tightening torque is precisely adjustable to any 
desired level. 
As it is now apparent, the insert according to the invention has therefore 
integral means for regulating the force which it can apply. This feature 
makes it an infinitely more sophisticated device than any other thread 
insert, in that it can be regulated by very simple and not time-consuming 
means to exercise precisely the degree of force which is desired. This 
feature makes the insert according to the invention especially suitable 
for use in delicate structures which are becoming increasingly important 
in industry through the spread of miniaturization. 
The slight upward movement of the bushing inside the hole which is 
described above as typical of the reversed-cone locking action, is 
therefore an advantage of this insert as compared with other thread 
inserts which are immovable after insertion. In the following, other 
embodiments of the invention are shown which make practical use of the 
"reversed-cone" upwards movement of the bushing. 
The inserts shown in FIGS. 5, 6 and 7 are based upon the same principle as 
the inserts shown in FIGS. 1 to 3, but the bushing is modified. As best 
shown in FIG. 5, the brass bushing is provided with a collar section 2a 
which is cup-shaped and has side walls 2b which are thin enough to be 
collapsed by axial pressure as is generated by tightening screw 9. The 
height of the sidewall 2b of the cup-shaped collar 2a above its base is 
advantageously such that when the insert is fitted into the bore 8 with 
the upper edge of the sidewall flush with the top of the box 6, the depth 
of insertion is essentially the one required to lock the insert in the box 
as previously described. Cup or collar 2a therefore serves in the first 
place as a spacing collar; if the insert is inserted flush. 
FIG. 6 shows that the insert fitted into the bore and ready for tightening 
screw 9 and FIG. 7 shows the screw 9 tightened to fasten the panel to the 
box. In tightening the screw, the cup-shaped spacing collar 2a had to be 
collapsed before tightening of the screw could be effected. 
Simultaneously, the bushing had been lifted enough to lock the insert 
inside the bore. FIG. 7 shows that the cup-shaped collar 2a formed by the 
thin side wall 2b of the bushing has inwardly collapsed in such a manner 
that it presses at least partly against and between the threads of screw 
9. The collapsed collar thus prevents displacement of the screw and 
thereby also of the insert, and it makes this type of insert essentially 
vibration and shock-proof. Instead of using a special bushing with 
integral cup, a standard bushing of any of the types shown in FIG. 2A 
through 2D may be used. 
Reverting to FIG. 5, this figure shows a further embodiment of the 
inventive concept in which the slight upward movement of the locking 
action is utilized for a special purpose. The insert itself is essentially 
the same as any of those shown in FIG. 7 and also functions in the same 
manner. However, after the insert has been fitted into bore 8 of box 6, a 
sealing ring or washer 5 is inserted into the space provided in the 
cup-shaped collar before the panel and the screw are applied. The height 
of ring seal 5 is such that it is flush with the top level of box 6 or 
slightly below. There is shown a ring seal 20 which is made of pliable, 
elastic material such as rubber or a synthetic plastics material, for 
instance neoprene. As it is evident and previously explained, tightening 
of the screw pulls the bushing upwards and thereby reduces the space 
available for ring seal 20, whereby the ring is deformed as to height. As 
a result, the compressed ring will seal the bushing to the bore wall and 
also penetrate between the threads on the bushing and the screw thereby 
sealing the screw to the bushing. Such sealed fastening is highly useful 
for many purposes in addition to those mentioned herein. Instead of a 
deformable ring seal 20 a collapsible ring seal 20a may be used. Such ring 
functions similar to the collapsible collar as described in connection 
with FIGS. 6 and 7. 
FIGS. 8A, 8B and 8C show other modifications of the insert according to the 
invention which will serve to make the insert vibration-proof. 
FIG. 8A shows a plastic plug 8a pressed into a cross hole 8b in the bushing 
which presses on the thread of the inserted screw. 
FIG. 8B shows a locknut 50 of any type attached to or forming part of the 
bushing. Both the structures illustrated in FIGS. 8B and 8C are well known 
and conventional. 
In FIG. 8C another structure is shown which again utilizes the typical 
movement upwards of the insert bushing. In drilling and tapping the axial 
hole in the insert shown in FIG. 8C, the section of thread in the "neck" 
of the bottle is drilled out so that only traces of a thread are left. 
This weakens the structure of the bushing at its narrowest section, with 
the result that when the screw 9 is tightened, this section collapses and 
presses against the screw, thus securing it. 
The embodiment according to FIG. 9 shows a very economical type of bushing, 
made of a suitable metal or hard synthetic plastics material, into the 
bottom of which a nut or locknut 30 has been pressed. This composite unit 
replaces the machined and internally threaded bushing shown in all 
previously described Figures. The locking ring 5 is not initially fitted 
upon the cone but in an annular cut-out at the rim of box hole 8. A 
manually or automatically operated tool 32 such as a punch serves to 
insert the insert into the hole and simultaneously slipping the ring upon 
the cone. The tightening of the insert is as previously described. A 
cylindrical protrusion 32a controls the depth of insertion. 
FIG. 10 shows an embodiment of the invention which is particularly designed 
for large size inserts and for coaction with screws which have a coarse 
thread, such as self-cutting screws. The insert of FIG. 10 is essentially 
a stamped and rolled replica of the insert of FIGS. 1 and 3. There is 
shown a bushing 35 made of suitable metal into which coarse female threads 
36 are pressed, and the blank is then rolled. The reversed cone 37 and its 
action are the same as previously described. The split ring 5 is also as 
previously described. 
FIG. 10 shows an assembly mode which can be applied to all embodiments of 
the invention, except FIG. 2D. Instead of furnishing the fastener 
assembled with the locking ring attached to its cone, it can be furnished 
in two separate parts so that the locking ring 5 is assembled by the user 
as part of the process of inserting the fastener. 
This mode is essentially suited for quantity production in which the 
components are fed, placed in position, and inserted by automatic means. 
However, the assembly mode hereinafter explained can also be used to 
advantage for assembly by means of a small insertion press, or even 
without any tools other than a hammer and punch 32 shown in FIG. 9. 
The split locking ring 5 is placed over bore 8 in the plastic box 6. 
Precise location may be assisted by a cut-out or countersink 31 at the top 
of the bore which, however, is not essential to the functioning of the 
device. The front part 4 of any embodiment of the fastener is then placed 
inside locking ring 5, and a tool such as a punch 32 is applied to the 
fastener bushing. As it presses down, the split locking ring or band 5 is 
expanded until it permits passage of the front part of the bushing. Next, 
the collar of the bushing presses locking ring 5 into the bore where it 
expands and presses against the wall of the bore. The punch presses the 
bushing deeper into the bore. When the step or protrusion 32a of the punch 
prevents further downward movement, the fastener has been inserted to the 
correct depth inside the bore. Now the screw 9 can be inserted and the 
fastener tightened as described with reference to FIGS. 3, 6 and 9. By 
these means, the manufacturer can save the sub-assembly of the locking 
ring without increasing the installation costs of the user. The sequence 
of automatic assembly and insertion as described in connection with FIG. 9 
can be applied to the embodiments described previously. It is essentially 
a question of economy and specific requirements. 
FIG. 11 shows an embodiment of the invention specifically intended to 
fasten a screw in a threaded bore in which the thread has been stripped or 
otherwise become faulty. The normal mode of repairing a stripped thread is 
time-consuming and consists in drilling out and re-threading the bore to 
take a larger screw, or alternatively drilling out, tapping and fitting an 
insert with inside and outside threads in form of a machined bushing, or 
of a spirally-wound coil of thread-section wire. Any insert according to 
the invention will function not only in a smooth bore as previously 
described but will lock just as securely in a threaded bore, regardless of 
the state of the thread and will afford great advantages in making a 
speedy repair of a stripped thread. 
In FIG. 11, an insert of the type of FIG. 1 is shown by way of example. The 
locking ring is preferably a grooved band 5g, but any of the locking rings 
shown in FIGS. 2A through 2D can be used. The screw for locking the insert 
in the bore is shown as a hexagon headed screw 33, by way of example. 
FIG. 12 is constructionally a thread insert, but it is also highly capable 
of acting as a closure for pipes which utilizes all features of the 
inserts according to the invention. 
It has been explained above with reference to FIG. 2D that the insert if 
modified as shown in FIG. 2D can serve to seal an opening against gas or 
liquids under pressures. The same modifications are embodied in FIG. 12, 
viz, the axial bore does not go through, and the lock ring 50 is made of a 
yielding material such as lead or a yieldable plastic, for instance, 
neeoprene, and does not require a gap or clearance against the cone root. 
The fastener is shown to be inserted into a pipe 41, to a depth which is 
sufficient to allow the full force of the reverse-cone action to be 
applied. As expansion proceeds through the turning of screw 9a, the lead 
ring is wedged tighter and tighter between the cone 3 and the pipe wall, 
thus sealing the pipe. Pressure in the pipe 41 bears against the flat 
bottom surface of the cone which means that pressure serves to reinforce 
and strengthen the sealing action by pressing the bushing upwards. It is 
in effect a closure with servo action which seals tighter in proportion to 
the pressure which it sustains. 
The closure thus obtained can be applied to pipes and pressures of all 
sizes and magnitudes. This includes the capping of broken oil lines under 
pressure, recognized to be one of the most difficult tasks in oil well 
operations. For this purpose, the bushing may be fitted optionally with a 
plastic O ring 52 which is seated in a groove 52a in the conical portion 
as shown in FIG. 12, or else with a metal piston-ring which is similarly 
installed in a groove. This serves temporarily to diminish the pressure 
below the bushing collar during insertion. As soon as the insert begins to 
"grip" and to expand the lead locking ring, the pressure against its 
bottom section takes over and completes the sealing action with great 
force. The direction in this operation is identical with that imparted by 
the screw, and both are indicated by an arrow in FIG. 12. 
The fastener according to the invention can serve conveniently to pick up 
and temporarily hold pipes from a crane or derrick. 
The insert is locked as previously described, that is, the fastener is 
inserted into the open end of the pipe and is secured by turning the screw 
and thus expanding the locking ring. 
FIG. 12A is a modification of FIG. 12. While in FIG. 12 a screw is used for 
tightening of the insert in pipe 41 by lifting the insert as previously 
described, the embodiment of FIG. 12A uses other tightening means to 
achieve the same result. More specifically, the fastener device of FIG. 
12A uses a hydraulic unit 60 for this purpose. This unit comprises a 
cylinder 61 in which is slidable a piston 62. The piston is secured to a 
rod 63 which, in turn, is secured to or integral with a collar 35a. The 
rod is slidable in a cloche 64 which supports the cylinder and is welded 
or otherwise fixedly secured to the rim of pipe 41 (see FIG. 12) or other 
tubular member to be sealed and/or supported. The upward displacement of 
the piston is effected in a substantially conventional manner by a nipple 
65 communicating with the space within cylinder 61 below piston 62 and 
connected to a hydraulic line 66. A second nipple 67 is provided in 
communication with the upper portion of the space in the cylinder. This 
nipple is normally capped and serves to release the hydraulic pressure. 
As it is apparent, pressurizing the cylinder space below the piston will 
cause lifting of the piston and, thus, lifting of the insert proper until 
bushing portion 35a is pressed against the bottom side of the cloche 
thereby sealing the pipe. 
The operation of the fastener according to FIG. 12A will be obvious from 
the previous description and is very similar to the one described in 
connection with FIG. 12. The insert is inserted into the open end of a 
pipe or other tubular member and the hydraulic unit is then activated as 
described. 
Other tightening means may be provided, such as vacuum systems, hooks 
engageable with cut-outs in the hole within the insert, etc. 
As it is evident, tightening means of the type described in connection with 
FIG. 12A may also be used in the previously described embodiments showing 
the use of a screw to be tightened for effecting lifting and thus locking 
of the insert. 
While the invention has been described in detail with respect to certain 
now preferred examples and embodiments of the invention, it will be 
understood by those skilled in the art, after understanding the invention, 
that various changes and modifications may be made without departing from 
the spirit and scope of the invention. Accordingly, it is intended 
therefore, to cover all such changes and modifications in the appended 
claims.