Note: Descriptions are shown in the official language in which they were submitted.
~5980~i
~his invention relates to inserts o~ the kind which have
a serrated or similarly formed exterior to provide a
plurality of projections fQr retention of the insert in
a hole therefor in parent material and which are in~talled
5. in position of use in a said hole by relative axial movement
;~ o~ the insert and material and, if desired, with the aid of
hi~h frequency or ultrasonic vibration of the insert or the
application of heat to the latter. Such inserts, usually
but not nece~saril~, have a threaded bore or shank f~r
10. receiving a threade~ member such as a screw or nut and for
example are widel~ used in components of plastics material.
~he invention has reference more particularly, but not
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l~ exclusively, to inserts of the above mentioned kind in ~
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~i; which at least part of the exterior of the insert is
`~ 15~ æerrated by a knurling or similar tool such as the inserts ~;
;, set forth in the specifications of my prior British patents
~ NOB . 1, 230,775 and 1,326,746.
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~, ~he object of this inve~tion is to provide an improved
~ insert of the above mentioned kind whereb~ installatio~ ~-
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20. is facilitated.
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, An insert of the character described comprises an exterior ;`
-~ part thereof having a series of annular peripheral taper
portions each of the same diameter and each of which tapers
' down from a rear shoulder thereof in a direction towards the
`.'J25. leading end of the insert, so tha-t said taper portions are in
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ba.rb~like formation, each said taper portion being
longitudinally serrated with serrations of V-~orm at
~: its rear part to provide a plurality of projections for
- retention of the insert in a hole therefor in parent
5. material, the serrations running out with forward
: reduction of each taper portion; a reduced diameter
cylindrical pilot portion at the leading end of the insert; ~
an external annular lip about the pilot portion closely ~ .
adaacent the leading end o~ said pilot portion and axially ~ ;
10~ spaced along t-he pilot portion from the adjacent taper
portion~ which lip is of taper form tapering down towards
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.~. the leading end of said pilot portion and is of substantiall~
:: smaller diameter than that of the said series of serrated
;, annular peripheral taper portlons for wall engagement in a
15. said hole in order to assist in maintaining initial axial
alignment and contact of the insert with the hole at the
commencement of and during installation of the insert
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therein; and a rear plain external annular peripheral taper
portion behind the rearmost serrated taper portion and of
2Q. substantially the same diameter thereof and also tapering -~
~: down in a direction towards the leading end of the insert
in order to close a said hole and retain parent material ~;
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therein on complete installation of the insert~
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In practice the constructio~ and arrangement is as follows,
. 25. reference being had to the aecompanying drawings in which:- ;
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~IGUK~ 1 is an elevation of the insert
at the commencement o~
` installation.
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FIGUEES 2 and ~ are rear and leading end views ;~
respec-tively o~ -the insert.
~rl ` FIGURE 4 is an elevation showing -the
insert fully installed, and
, ~IGURE 5 is an elevation of a male form
-~ of the insert providing a
10. threaded stud. ;~
;~ ~he insert shown in FIGURES 1 to 4 is basically in accordance
with tha-t described and shown in the specifications of my prior
British patents aforesaid in which the insert 1 is provided
with a threaded bore 2 for receiving a screw and is formed on
7l~ 15- its exterior periphery~at 10 with a series of taper portions 6 ~;
x7, ~ each of which forwardly reduce in diameter in a direction
towards the leading end of the insert.
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ach taper portion 6 is serrated at 7 at its rear part of ~ ~`
greater diameter so as to provlde a pIurallty of projectlons `~
~; 20. 60, the serration 7 r7~nning out with the forward reduction in
diameter of the~taper portion 6. Serration 7 of the taper
portions 6 can be conveniently effected in practice and to the
V-form shown by~a suitable knurling operation. ~- ;
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: ~he taper portions 6 and projections 60 thereof are arranged
:~ in buttress or barbed formation so as to provide a series of
shoulders 16 each de~ined between the rear end of one taper
~ portion 6 and a leading end of -the next portion~
: 5. ~he insert can be ins-talled by a simple push opera-tion in a - -
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hole 19 of suitable size and depth in parent material such
f ' as metal, wood, thermo-setting or o-ther plastics material of :;
.",
;. a component 13. Alternatively it can be installed in
thermo-plastic material with the aid of high fre~uency or -
10~ ultrasonic vibration or by the application of heat to the
.` insert by a thermal gun whereby parent material immediately ;:
` about the inser-t 1 in the hole 19 is temporarily softened
;; or melted so as to run in relation -to the insert 1 for ~:
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;~ obtaining ~irm securing or encapsula-tion of -the latter in
.l 15. the hole af-ter the material has solidified. Such operation
, ?, may -take place in only a very shor-t interval of -time eOg.
of about one second or less.
During such irlstallation the insert 1 is received by the
hole 19 either by driving the insert into the latter or by
` 20. moving the material relative to the insert whichever is -the ~ :
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~ most convenient in practiceO
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For the purpose of such in~tallation and in accordance
wi-th this invention, a reduced leading end por~ion OL' ~`
pilot 12 of the insert is provided with an external lip
or bar~ 20 shown o~ ~orwardly tapering c~nnular form -
5. which is preferably also serrated at 27 to a shallow
depth i.e. b~ the same knurling tool during the serration ~-
of the taper portion 6. ~hus the serration 27 of the
lip 20 is a continuation or witness of the serration 7
on the taper portions 6 while it will be noted that the "
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10. maximum diame-ter of the lip 20 is substan-tially smaIler
than the maximum diameter of -the taper portions 6 at 10.
~specially in the case of a cored hole in plastics material ` -
e.g~ having a draft angle of the order of 3 inclusive, and
on initial introduction of the insert 1 into the hole 19
15~ -the lip 20 contacts the wall of the hole at or adjacen-t
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~ the mouth of the latter and thus assists in initially
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~ maintaining axial ali~nment of the insert 1 w~th the hole 19.
`~ ~his is maintained as the insert 1 is driven fully into the
hole 19 where the lip 20 also provides positive location at
20. the bottom or lnner end o~ the hole. As a result the ~;~
~, ~ tendency of the insert to pivot or rock out of axial alignment, ....................................................................... .
~:r: ~ : ~uring installatlon is avoided or very greatly minimiséd~
~ In the case of ultrasonic ins-tallation or by means of a
:s~, thermal gun, mol-ten parent material is able to flow over ~ -
25. the lip 20 and about the taper portions 6 in obtaining
secure installation of the insert in the hole. Owing to
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~S9~06 -:
-the buttre~s or barb like formation of the taper
portions 6 and projections 60, the insert 1 has a
high resistance to axial pull-out load when ins-talled
in parent ~aterial, whils-t the serration 7 of the
5. taper portion 6 also resists -the tendency of the
inser-t to rotate relative -to the parent material when
the insert is under torsional load.
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~he insert is also shown provided with a rear taper
g portion 26 of plain annular form tapering down in the
10. same direction as the taper por-tions 6 i.e. towards the
leading end of -the insert 1. -~
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This plain taper portion 26 is of substantiall~ the same
diameter as the taper portion 6 but the taper angle may
be of the order of 45 as against 22 of the taper
;1 15. portion 6. However these and any other values quoted
~ herein are given by way of example only and ma~ be varied
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, according to practical reguirements.
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`- The plain taper portion 26 provides an effective stop
against the surface of the parent material about the
20. mouth of the hole 19 for providing a suitable finish for
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aesthetic purposes and also fully closes the hole
especially as regards grooves formed in the wall of the
~ ;f
latter by the broaching action of the serrated taper
~` portions 6.
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Again in -the case of ul-trasonic or -thermal gun
installation, the plain taper portion 26 effectively
prevents or minimises back spew of mol-ten plastics
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material from the hole 19 as the installation of the
~` 5. insert 1 is completed.
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A further practical advantage arises from the fact that
the rear face 260 of the plain taper portion 26 provides
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~ a relatively large bearing surface for the horn of ultra~
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~; sonic installation apparatus or of a thermal installation
~;' 10. gun.
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~he foregoing features and advantages of the insert are
achieved with little or no incr~3ase in the cost of
manufacture or production time per insert.
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~; ~IGUR~ 5 shows an insert body 1 having substantially
~5. the same exterior form as that described including the ;~
provision~of a lip or barb 20 on the reduced pilot ~-
portion 12. However instead of a threaded bore, the
body 1 is pro~idad with a co-axial threaded shank or
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~ stud 22 of reduced diameter extending from its rear end.
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20. ~he formation of the bore 2 or shank 22 of the insert 1
depends on its intended purpose and for example may be
of plain form.
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