CA1058923A - Bolt anchor - Google Patents

Abstract

BOLT ANCHOR

ABSTRACT OF THE INVENTION:
A head-out expansion anchor which is particularly suitable for securing a heavy object to a support such as a floor or wall is disclosed. The anchor includes an elongated and generally cylindrical anchor sleeve which is formed from flat sheet stock and rolled to a given diameter wherein the confronting ends form a longitudinal slot extending from end to end thereof. A bolt is provided and includes a shank, having a diameter corresponding to the diameter of the formed sleeve, and a threaded portion of a reduced diameter at its leading end thereof. A tapered or conical transition portion is provided between the shank and threaded portions of the bolt. The threaded end receives a tapered expander cone having a threaded bore therein and wherein the sleeve is disposed between the shank and the expander cone. The expander cone is drawn into the expander sleeve by rotating the torque-tool engaging end of the bolt, such as by means of a wrench. The corners of the expander sleeve, at its trailing end thereof, are deflected outwardly to provide a pair of sharp resilient teeth for biting engagement with the side walls of the bore. The expander cone is provided with at least one radially pro-jecting rib or tab which is received within the slot of the expander sleeve at its other end thereof, thereby to prevent relative rotation between the cone and the sleeve.

Description

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ï~8~z3 Bl~CKGROUND OF THE I~ENTION:

The pre~el~t invention relate3 to expansion anchors and, ~ore p~rt~cularly, to such anchoxs wherein an 2xpan~ion ~leeve ~L8 e~xpanded radially by dra~i2lg a taper~d expander 5 eles~ t lnto the leading ~nd of ~e sïeeve and by ~an~ o~
an actuating element which extend~ outward:Ly of the bore hole.
Exp~sion anchors of the head-out t~ype are well known a~d have ba~n widely u~ed in ~3e artO These anchor~ have th~ ad~antage that the anchs:~r ~txucture does not permaneI~tly 10 pxojec~ above the floor or wall surace a~ a stud anchor does, or example. That i8, s~pon removal o the boït in such a he~d-out anchor, a f lush hole remai~s in the masonry ~ux~ace. Thi3 i~ particularly important where heavy equip-m~n1:, which i~ other~i~e too heavy to lift over a projecting 15 ~a~tener~ i~ installed in 3uch a mannex ~ it must be remov~d or relocated.
One ~uch l~own head-out anchor includes a pre-a~sembl~d lock nu ver the sh~ of the bolt which is embedd~d irlto the side walls of the predri~lled bore by turnillg t:he head of - 20 the bolt through a limlted nu~ber of t:U~15. ~hi~ des~ice ~uf ~or~ with the disadvantage that there i n~ po~itive load re~ction between the expa~sion anchor and t:he ~ide walls of ~he bo~e a3 lthe tapered expansiLon cone i8 ~ituated abn~re ~he expan~ion sleeve . That ~ s ~ in order to provide a positi~e 25 load raac~ion agai~l~t the wall~ of ~he bore hole, the taperl3d expansion cone mu~t be dispo~ed below the expansion sleeve in ord~r to p~ovide the positive load ~eaction.
~urther, ~uch expan~i~n anchor~ are not readily re-tightened a~ter yielding to the high ~tre~ load~ as occa~ioned by 30 prolonged use.

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' " , ' ' `' ~ ' ' ~513~3 Others types of expansion anchors are known wherein an expansion anchor sleeve is expanded radially by drawing an expander element into the sleeve from one end by way of an actuating member which extends into the sleeve from the other end. These devices, however~ suffer with various disadvantages such as complexity and expense occasioned, for example, by the need for a screw-machine operation for the manufacturing of each of the individual parts.
Theseldevices further suffer from the disadvantage that under the stress of high tension or pull-out loads, the expander element can be pulled all the way through the sleere which, accordingly, results in a failure of the expan-sion anchor. While attempts have been made to solve these problems, as byutilizing additional piece parts such as rings disposed at the end of the expander member which is remo*e from the sleeve, such cures function to fur-ther complicate the construction of the device and to add to its manufacturing cost.
Another known expansion anchor of the last-mentiQned type util-izes polymer rings disposed between the trailing end of the expansion sleeve and the shoulder of the bolt. The ring is compressed or even crumbled if it is necessary for the bolt to be drawn downwardly during the expansion process such as when an undesired space is initially included between the concrete ZO surface and the object being bolted to the concrete.

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~L0S~923 SU~IARY OF THE INVENTION-According to the present invention there is provided an expan-sion anchor for use in a bore hold formed in a g:iven structure comprising:
an actuating element having a shank of a given diameter and a threaded lead-ing end of a reduced diameter; and expansion sleeve surrounding said threaded ~ :
. portion, the diameter of which substantially corresponds to said given dia- :~
; meter and the trailing end of which initially engages the walls of said bore;
a tapered element threadedly engaging the leading end of said threaded por- : ~.
tion; wherein the leading end of said expansion sleeve is expanded radially and into wedging engagement against the walls of said bore by drawing said tapered expander element into the leading end of said sleeve; and~ wherein said actuating elernent includes an integral tapered transition portion be- .
tween said shank and said threaded portion which initially engages said trailing end of said sleeve against said walls in fixed relationship there- : :;
with prior to the radial expansion of said :leading end of said sleeve and ~ whose taper with respect to the axis of said actuating element is substantial~
-. ly greater than the taper of said tapered element for radially expanding said ~ trailing end of said sleeve into deeper engage~nent with said walls while : drawing said actuating~ element into said sleeve after said leading end of said sleeve is radially expande.d into fixed engagement with said walls.
In a preferred embodiment, the integral transition pbrtion is .;~
- conically tapered. ``

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: , : . . .: , BRIEF DESCRIPTION OF THF D~WING:
The advantages of this :invention will become more readily appre-ciated as the same becomes better understood by reference to the following de-tailed description when tc~ken in conjunction with the accompanying drawing wherein:
Figure la is a preferred expansion actuating means, i~ the form of a head-out bolt, in accordance with the present invention, : ~igure lb and lc respectively illustrate an expansion sleeve and a preferred expansion cone suitable for use with the actuating means of Figure la;
Figure 2 is a perspective view of the expansion sleeve of Figure lb, in accordance with the present invention, after having been formed from a slot sheet metal material;
Figures 3a and 3b are perspective views respectively of a prefer-red expansion cone, and an alternate embodiment of an expansion cone;
Figure 4 is an enlarged cross-sectional view of the expansion cones of Figures 3a and 3b illustrating somewhat more clearly the double tapered angular configuration thereof, in accordance with a feature of the .~ present invention;
~ 20 Figure 5 is a ~iew taken along the line S-5 of Figure lb;
Figure 6 is an assembled view, in partial cross-section, ~'~

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of an exp~3:i on ancho;r, ln accor~laY~ca with the principles of th~ present in~ention, sho~n 1~ cor~ ction with an axlally over~ized ma~onry bor~3 h~le; and, ~gure 7 illuatrat~ a vie~q similar to Flyure 6 and S further lllu~rat~a a ~truc: tural fPatur~ whexein the actuatirl~ me~5 iS draw~l downwar~ly in o th~ bora hole to comp~n~atc for unde~ir2d lnitial spri~g b~ 3;wearl the aetuati~3g ~a~s a~ad the laaterial ~ ace.

DETAILED DESCRIPTIOP~o .... .. . . .
Referring now to Figura la~ there is snown a pr~erre exparlsion ac~uating ~all 10 which ~ake3 th~ form of a head-ou~ bolt ha~ing ~ threaded leading end 12 and a ~hank 14 at its tralling erld. Th~ trailing end i3 outwardly terminated in ~n i3ltegral torque-tool erlgaging mean~ 16 in 15 t~e ~o~ o a bolt head and haviny an inte~ral wa~her 18 provlded therewith. Expan~ion act:u~ting m~arls 10 preferably - compri~es a high-grade ma~erial such a~ Ç;rade 5 alloy ~teel.
Further, the threaded end of mean~l 10 is provided with fine thread~ for maximum effective drawing force applied to the 20 axpander cone as well a~ maxi~um t:en~ile s~reng~h as will be di~cus~ed more fully hereinafter. That i8,, t:he thread is selected to ~ini~i~e the dep~;h of the roots ar~d to be whate~Jer ~aximum nomi~al ~ize t~at will freely pa~s thru axpaJasios~ ~leeve o~ appropriate thickness, thus providirlg 25 ~aximum root diaDIet:er and ~kiv~a dia~eter d~erlsio~ for maxi~um ten~ioAal strength.
Figur~s lb and ïc ~e~pec ~ vely illust~a~e an expansion sleeve ~0 a~d ~n ~!3xpal~der ele~ent or cone 30 suitable for u~e with ac~uating mean~ 10 of FiglLre la, as w~ll be 30 described m~re fully h~reinat~3r.

, . ~, , . , ~. , , : , 3~ 7 -A conlc~î tran~:1 tiorl portioll 11, of a~ le C, 1 provided betwl3en the l~ading threaded portios and the trailing portic;~n of the actu~ing means or bolt 10 to allow l:olt 10 ~o draw it~elE downwaLrd by radially ~xpanding th~
5 t~aillIlg e~nd of sleeve 20. Thi3 corlical portion 11 i~ o~
sufficiently wide lllcluded angle~ such tha~ tha sleeve 20 will m:>t b~3 prematurely ~xp~ded as the an~hor a~sembly is pushad into the bo~e hol~. Thi~ provi~ or allowir~g the bol~ to dr2w i~elf dow~w~r~ p~r~lcu~l~ u~aful in tho~e 10 3ituations wher~ there i~ a space be~ween the c:oncrete ~urface aIld the ob~ct 3~eing fa~ened and wherQin ~hi9 gpace re~uire~ tantial bolt tension to draw..the object fi~ly agaln~t the concrete. The radia} expan~io~ o~ ~e trailing e~d of the ~leeve is ne~::e~ ry becau~e the threaded cone 30 at the 1~3ading end will have previ.ously locked the 31eeve again~t ~e wall of the bore hole.
RQferring ns:~w to ~igure 2 ~ there i~ 3hown a persp~ctive view of *xpan~ion ~lQe~3 20 in acc:ordall~e ~ith the present inventioll. Expan3ion ~ eave 20 i~ pref~ra~ly in~tially pro~id~d ~ the ~fla~N~ thalt i~, a8 ~ blar~lc oiE rela~ive ~hick ~he~t mat~l material. The ~lat or bl~ re~erably ~nit~ally provided with aligned longitudinal ~lots 22 and 24 which rsspecti~ely extend from oppo~i1te eT~ds of the blank and lor~gltudinally eacte~ld a gi~n di~tance into the ~leev~
~5 whlle leaYil~g an intermediate suppt)rt w~b thereb0tween. The blaIak is rolled ~uch that it~ c:on~Erontillg end~ pro~ride another longitudinal ~lot 26 extending from e~d to end of the no~d cylindrically ~hap~d ea~pansion sleeve. The uppsr cornex~ o~ ~lot~ 22 ~nd 26 are preferably deflected or ~lared outwardly ~ at 28 ~o as to provid~ ~harp yat ~:
deflec~able tin~-like bite edges for engagemen~ wit~ the '' ' ' ' ' .

8 - N.G. Scheuer ~
side wall 3tructure or material of the bore hole as will be described more fully hereinafter. Thi~ feature is further illustrated in Figure 5. Further, during the manufacturing operation, the direction of sheer of the blank of sleeve 20 can be selected such that the sharp edge of the stock is disposed along the exterior diameter of sl~e~e 20. The outside diameter of sleeve 20 is selected to approximate ~:
or correspond to the outside diameter of shank 14 of actuating means lO in Figure l. However, as described more ~ :
fully hereinafter, in currently preferred practice, the ~;
diameter of sleeve 20 is deliberately oversized.
R~ferring now to Figure 3a, there is shown a per~pective :~
view of an expander element or expander cone 30 in accora- :
- ance with a preferred embodimen1: of the pre~ent invention. ~
lS It can be seen that cone 30 is provided as a screw-machine : ~:
part having a central thxeaded bore with threads corres~
i ponding to the fine threads provided at the leading end 12 -of actuator mean~ lO of Figure l. Cone 30 is provided with ..
a first tapered portion 32 which extends from the trailing ; -~
:: 20 end o~ cone 30 toward the leading end thereof. At an .:
intermediate point along the longitudinal surface of cone :~
30, a transition occurs whexein the angle of the taper is increased to provide a second tapered portion 34 the func- -;
tion of which will be described more fully hereinafter. i~
Finally, cone 30 i9 provided with a pair of diametrically ~ opposed tabs 36 and 38 which are ~ent from the edge portion : of the trailing end of cone 3 0 .
Referring now to Figure 3b, there is shown an alterna- : . :
tive embodiment of an expander cone 30' in accordance with the present invention. Cone 30' differs from cone 30 of Figure 3a in that a knurled portis:)n along a circumferential `:

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~5~39~3 - 9 - N~G~ Scheuer -l band at the trailing end of cone 30' is providedO The knurled portion 39 provides essentially the same function as tabs 36 and 38 of Figure 3a~ by gripping the inside diameter of the expansion sleeve so that the cone does not turn while being drawn upward by the bolt~
Referring now 1:o Figure 6I there is shown an assembled view of partial cross-section of an expansion anchor A in accordance with the present invention. It can be seen ~hat ~ ;
the axial depth of the bore B in the masonry M exceed~ that of the o~erall length of the expansion anchor A. This is of no consequence a~ the expansion anchor A in accordance with the present invention grips itself within the bore by means of radial expan~ion against the bore walls irrespec-c tive of the depth of the bore. That is, it need not bottom ,, .: in the ~ore. Further, the anchor can also be readily used l~ with through holes or bores. Il: can be seen that once anchor A i~ nnserted into the pre-drilled ~ore! the deflected co~-~; ners 28 of s~eeve 20 bitingly engage the surrQunding mater- ...
v ial of the bore wall ~o as to prevent subsequent rotation of ~leeve 20 as torque is applied to b~lt head 16. However, :~
these tabs are designed so as to readily de~lect inwardly ;~
~ the anchor assembly i5 installed through a comparatively :
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.: tight hole in a metal object or machine base or if the sleeve must pas~ by a hard particle in the concrete, Fur .
~her, as the torquing operation continues, cone 30 is drawn : 25 upwaraly into sleeve 20 thereby causing radial expansion of : sleeve 20 ayainst the surrounding material of the bore until : the sleeve is snuggly wedged against the walls of the bore : -B. Thereafter, anchor bolt l0 can be threaded away and removed from bore B while ~leeve 20 remains firmly fastened .

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within ~che bore B and wedgin~ly bngage~ with ¢one 30.
Figure 7 i llu~trateEs the ~unctiorl of the previou~ly de~c~i~ed cc3nical ~can~ltion por ic3rl 11 ox' a~chor bolt 10 wherein the trail ing Rnd of sleQve 20 has b~erl expanded by 5 the corlical transition po~ on to allow a final downward mo~ nt or greater pene~ra~ion of anchor bolt 10 to close up any unde5ired ~pace.
Figure 4 lllu~trates somewhat more cle~rly the diDu3n-~ional rela~io~hip of ~he multiple-function s~ruCt~re of 10 exparl~er cone 30. It can be ~een that tapexed 3urface 32 i~ provided wi~h a given initial ~hallow ~apex defining an angle $~ ; arld that the 3econd tapered ~ur~aGe 34 i8 p~ovided wilth a steep~3r taper at ~he bo~tom or leading end o~ the cone whlch is designated a~ ~ in F.igure ~. This double t~per ~eature, in accordance with th~ present inven~ion, ~ignificantly increa~es the applicability and, thare~ore, ~he u~ility of ~he expa~l ion anahor~ That is, the shallow ~aper c~e of ~apered por~io~ 3~ normally fully e~pand~ the ~leeve i~ high-~tr~ngt~l concrete ~ith app~opriate 20 torquo ~r~ on the anchor bolt 10. However, in low-stxe~gth concrete, the ~teep~r taper ~ i8 drawn i~to ~he sleeve a~ an again appropriate torgue i~ appli~d to the anchor bolt 10. Thi~ allow~ ~or ~he de3ir~d le~el of ~ ~a~tening torque ev~n wi~h a wide variatio~ the strengths '' 25 0~ 8ub8txate materials.
It will be appreciated by those ~killed in ~he art~
that in ~he~e lo~-strength s~bs~ra~e materi~l situations, : . a shallow taper alone could be dra~n completely through the sleeve, ~ven at rela~ively low tor~ue level. ~n this regard, the ~teeper taper at the bottom of the cone is intended to o~er grea~er resi~tance ~o ~ension or pull~out loads which ~53~3Z3 ~
might othaIwi~;~ draLw ~ ~hallow taper t.hrough tha ~leev~
In any event, m~xim~l allowa~le bolt tor~u~ nor~ally attained ~t the point wher~ the steep~:r taper ~ enter3 ~he ~leeve 20., Howe-rer, the steeper taLpar provides the addPd ~eature ~at th~ ~xpan~io2l anchor in accordance with the pr~ent in~rerltion can with~tand greater pull-out or tensile forces with las~ ~lip or cr~ep tha~ i~3 possible with ~hallow taper alongO Fu:i:ther, any slip or creep resulting ~rom ten~ile loads or bolt ten~ion can be ~eadily comp~n~ated Eor by merely re-tightening t~he bolt.
~ Althougll it is ~omewhat difficult to depict in the ~ ~ previou~ly described Figures~ it should~ be appr~ciated that~
in accordanc:e with a further feature of the pre~en-t invention~
expandc3r c~ane 30 and expan~.ion ~le,eve 20 are dleliberataly over~ized., For exampla, the exparlsion a~chors l~tanded for :; the normal 0.25, 0~50 and 1.00 inc:h boxe hole application~, .
are prefer~bly greater than t:hese normal diameters~ for example, by a value oi~ appro;7cimate~1y 0 ~ 010 inche~ . In c:urrently pr~3ferred prac:tice, ~Eor e;xample, the " 0 . 5 " inch .~ 20 anchors are provided with OoS10 irlch dia~ter members. Thi~
oversized structural :Eeature is utilized cn ~oth the expa~ler colle 30 (see dimen~ion D in Figure 4) and expansion F3leeve 20 in ~t~ diametric dimen~ion. Thus, by :Eorcir~g an over~
b 8ized ~leeve of maximum poqsible material thickness over an over~3ized cone, the maximum pos~ible expanded diame ter i~ realized in both low ar~d medium s~renq~L concrete. The~e ov~rsized di~n~ion~ are ne~er1:hele~8 accomodated by the re8pective bor2 holE3~ as m~onry drill~ ~ for example, typically measure 0.,015 ts 0.025 inches greater than ~heir 30 "noIIllnal" diamatex~Bo Fur~her, in actual practice, these ;

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, " , ; , , , : . ~ ,:: . , drill blt~ drill hol~ e~.7erl larger tharl their over~.i2~d dimerlsion~ .
Thf~ over~ize dime.n~ion3 typ.ically proYided in masonry drill bits 1~ n ce~axy to accomodate wear O:e theix - S car~ide t~p~ and because the bits oten dc not dxill straight hol0~, Thu~ an over~ize hole i5 needed to ~2nRure that typic:al one piece a~chor shell~ or shaft~ ~ill fit; into the hole.
Thus, ~tated somewlhat dif ferently, l:hi~ fsatllxe, in ac:cordanc~ with the pre~ent invQntion ~ ~ills a s~tantial portio~ of the heretofore unu~ed ~pace i~ t~e bore hole prior to exp~ion o~ the sleeve --i,e., even be~ore the ~leeve is expanded-- in order to achieve the greatest pos~ible 3ub~equent expansionO In~ currently pre~erred lS practice, the over~ized dimension~ of the e~pansion sleeve 20 and ~xpander cone 30 ~e ~omewhat les~ than the typical m~ximum ovar~ized dim~n~ion of th~e typical masonry drills.
Thus t gOIIIe 0~ the previollsly unu~ed ~pace ls left unu~ed.
How2~er9 it ~hould be appreciated that this is done because ma~onry drill~, fox example, typically do not drill per~ectly stra$~ht hole~ and, accordingly, ~uficien~ clear-ance mu~t be provided arld aïlowed to ensur~ that ~he l:olt anchox as~embly *rill fit the hol~.
It should IlO~Q be appreciated that ~e thr~e piece

2~ expansion a~qe~ibly, in accorda~ce with the pre~ent invention, al80 fits tog~er loo ely enough ~o that the oversize cone and expanslon ~l¢eve ara able to be easily deflected out o:E
true aligN~nt with ~he bolt while being tapped into a drilled hole tha~ typically may not be ~tr~ight~
3û What ha~ beeal taught9 then, i~ arl expansion anchor .

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pirticularly ~uitabl~ or ~30nry ~tructure~ and the llk~3. The ~xpan~ion ~chor, in ~ccord~nce wi th ~he prasent inlvention, f~cllltat~, not~bly, a wide ra~ge of applicatioll~ an~ utlll~y while protriding a relatlvely 5 stmple as~ inexpan~ d~vic~ to ma~ufacture.
~ he form o~E th~3 in~3n~10ns illu~rated and de~s~ribed herein ~:~e but preferred embodinenlt~ of 'ch~e teachiny~
and th~} form~ curr2n~.1y prefQrred for manufacture. They are ~hown a~ illu~tration~ of the inventive co~cept~
10 however, r2Lther tha~ by way o limitation, andl it i~
ted out ~hat variou~ mod~ fication~ and &~taration~
~ay b~ indulged in wi1:hin ~he 5cope of the appended clai~

WJM: po Apr~l 2~; 1976 ,,~

Claims (5)

WHAT IS CLAIMED IS:

1. An expansion anchor for use in a bore hold formed in a given structure comprising: an actuating element having a shank of a given diameter and a threaded leading end of a reduced dia-meter; and expansion sleeve surrounding said threaded portion, the diameter of which substantially corresponds to said given diameter and the trailing end of which initially engages the walls of said bore; a tapered element threadedly engaging the leading end of said threaded portion; wherein the leading end of said expansion sleeve is expanded radially and into wedging engagement against the walls of said bore by drawing said tapered expander element into the leading end of said sleeve; and, wherein said actuating element includes an integral tapered transition por-tion between said shank and said threaded portion which initially engages said trailing end of said sleeve against said walls in fixed relationship therewith prior to the radial expansion of said leading end of said sleeve and whose taper with respect to the axis of said actuating element is substantially greater than the taper of said tapered element for radially expanding said trailing end of said sleeve into deeper engagement with said walls while drawing said actuating element into said sleeve after said leading end of said sleeve is radially expanded into fixed engagement with said walls.

2. The anchor according to Claim 1, wherein the unexpanded diameters of the circumference of said sleeve are significantly greater than said given diameter thereby to at least partially fill the void of a significantly oversized bore hole.

3. The anchor according to Claim 1, wherein said integral transition portion is conically tapered.

4. The anchor according to Claim 3, wherein said transition portion forms an angle of approximately 60° relative to the axis of said actuating element.

5. The anchor according to Claim 1, wherein the taper of said tapered element increases at the leading end thereof.