IE38442B1 - Self-locking fastener - Google Patents

Abstract

1394027 Lock nuts and bolts STANDARD PRESSED STEEL CO 22 Feb 1973 [22 Feb 1972] 8710/73 Heading F2H A self-locking nut or the head of a self-locking bolt has on its bearing face an array of substantially radial teeth 20 of saw-tooth crosssection the crests 22 of which are radiused or formed as flats 30 to limit penetration of the teeth into a workpiece when the nut or bolt is engaged with the workpiece. The crests 22 of the teeth may define a radial plane or a frustoconical surface. The teeth may be surrounded by a smooth annular rim 18 which engages the surface of the workpiece to contain stress concentrations caused by the action of the teeth 20 within its circle. The rim 18 may form a continuation of the surface defined by the tooth crests (Figs. 4, 6, 8, 10, not shown) or may be slightly inclined to that surface (Figs. 7, 11, not shown) or may be convexly curved in radial section, being tangential to the crests of the teeth where it meets them (Figs. 5, 9, not shown). The roots 24 of the teeth may be linear or curved when viewed in radial section. Reference has been directed by the Comptroller to Specifications 1,268,862 and 1,326,380. [GB1394027A]

Description

384 43 The present invention relates to self-locking fasteners and, in particular, to bolts, nuts and the like having serrated bearing surfaces which provide resistance against the fastener becoming loosened unintentionally after it has been seated.

A serious problem in Joints secured together by threaded ■embers is the possibility of Joint separation due to :< nut backing-off from a bolt or a bolt backing-out from n nut or othsr Internally threaded member. Generally, this result can occur when the Joint is subjected to vibrations.

Various proposals have been suggested in the past to either eliminate or greatly reduce the unintentional loo.tening of threaded members. Because of the wide variety of applications in which this undesirable result can on-ur, many different types of locking devices have been developed. One approach has been to treat the bearing surface of the fa.-4tem.-r in such a manner that the resistance to relative rotation between the fastener and a workpiece in which the fastener is installed is greater than the resistance to relativ.-between the mating threads. Vs a result, the runistance to rotation between the mating threaded parts no longer is the critical factor in determining whether the threaded parts will turn relative to each other.

One important requirement of these fastener* is thai th-"off" torque (torque required to loosen a t i »'•"'•r) be greater than the "on" torque (torque required t.r> sr-.ii n fastener properly.) This relationship should exist lor v« i 1 installations and removals of the fasteners.

Because the bearing surface of these fasteners, IV r i hi- !l 8 4 4 •! most part, is serrated or is - provided with teeth oi Lho like which are arranged to dig into the vorkpiece to create resistance to relative rotation between the fastener and the workplace, some damage or marring of the workplece bearing 5 surface will occur as these fasteners are seated and removed.

Such damage to the workplece causes it to weaken. Honco, a second important requirement of these fasteners is that rhe effects of marring or damage to the workplece be minimized.

Generally, prior art fasteners provided with a locking 10 characteristic in the bearing surface fail to satisify concurrently these and other requirements. Those fasteners available at the present time having improved "off" torqu<- to "on" torque ratios dig into the workplece in such a mann"! otto such an extent as to weaken greatly the workplece. "Notch" 15 effect, the build up of stress concentrations, is a common result and may cause fatigue failure of the clamped parts.

This problem becomes more acute as the thickness of the work-piece is reduced. Those fasteners available at the present time having reduced adverse effects on the workplece provide 20 insufficient "off" torque.

The drawbacks of this type of prior art fa-ten^rs ar» overcome in a fastener such as that disclosed in Patent No. 33973 and Pate/it of Addition No. 3S353. These patents are concerned with a self-locking fastener which provides a resistance 25 to unintended rotation between the fastener and wurkpieoe ami yet causes a minimum amount of marring of the workpiece surface with which the fastener bearing surface is i:: This is accomplished by providing a smooth surr'ar? annul.ir 4 42 ring about a plurality of ra«Jiully disposed serrat ioiik which, upon engagement, with the workpiece, opposes further penetration of the serration* and controls the extent of penetration of the »e.-rations.

Thus, it is an objert of the present invention to provide a new and improved sell'-1 ock ing fastener having a locking mechanism provided in the bearing surfare of the fastener and which is also provided with a stress regulating configuration within th»* locking mechanism to control the extent of penetration of the fastener into the workpiece.

It is another object, of the present invention to provide .» self-locking fastener of this type which provides improved resistance to unintended rotation between the fastener and <t workpiece and yet causes a minimum amount of marring of the workpiece surface with which it is in contact.

Another object of this invention is to provide a self-locking fastener which provides improved resistance to unintend rotation while minimizing the bearing surfucc area of the fastener neressary to contact the workplece.

It i^ ii further <>b.J><i «»f the present invent ion In provide a self-locking t'i»*lener which is relatively .simple in construction and inexpensive to fabricate.

According to the invention a self-locKing fastener has a driving porrion with a radial bearing surface Including a Of plurality of annularly disposed serrations/ generally saw-tooth Shape when viewed along a cylinder concentric with the longitudinal axis of said fastener, the crests of said sex rat ions being Shaped 10 'J 8 I -1 U and control the extent of pi-not r.n i un of the sernu ioii.s in .taid bearing surfucc of the fas t <-ne r into a wo rk |> i • •• wti-Ti the fastener is ope r« t. i. v«-1 \ iMi/Mtged within s.ml workp i .

The extent of penetration of said serrations into a worV-piece may be limited and controlled by each serration having a crest configuration such as a radiused edge or a flattened ridge. The annular ring may bo in tlic form of a bearing surface of substantial width radially outwardly of said serrations, the crests of said serrations lying in an imaginary surface which is a continuous radially inward extension of said annular ring bearing surface.

By way of example embodiments of a se'f-locMng fastener are now described with reference to the accompanying drawings, in which:- Figure 1 is a perspective view ropreaentative of a self-locking bolt constructed in accordance wi t.h the present invent ion: Figure 2 is a perspective vi<-w, on an enlarged oi a portion of the bearing surface of the bolt, illustrated : ri Figure 1; Figure 3 is a view similar to Figure 2 showing in alternative embodiment for -lie serrated segment of the hearing surf ace; Figure k is a vertical section of the bolt illustrated in Figures 1 and 2; Figure 5 is a vertical section of another embodiment of a bolt constructed in accordance with the present inversion; Figure 6 is a vernc?l section of yet another :n:> m - - r. t 36442 uf a bolt const I'ucted in ac c ordatic *• with the prt-sent invi'iit ion; Figure 7 a vw t i cnl section ol" >i'mt her embodiment of f« bolt constructed in accordance with Uf present invent inn; Figure 8 Is a vertical section of a first embodiment of a nut constructed in accordance with the present invent ion; Figure ') is a vertical section of another embodiment of a nut constructed in uccordance with the present invention; Figure 10 is a vertical section «>j yet another embodiment of a nut constructed in accordance with the present in\ention;and Figure 11 i> a vertical set-i.i"ii ol' another embodiment of a nut. cuiiMtructt'd In accordance with the pi esent invention.

Referring to Figure;. 1, 1' and a se I f-1 ocki n/; bolt constructed in accordance with the present invention includes a threaded shank 10 and a bolt head 12 at one end of -shank It).

Bolt head 12 has a wrenching section 1'« and a bearing flange lo.

The bearing surface of flange Ltj may include <.m <»nnular ring 18 and a plurality of annularly disposed teeth-like serrations 20 located within ring It*. When .-err.it \ .•!.«. 2U are viewed along a cylinder mncsntri c with t tie lop.j; i t uu i ti.i 1 a x i .-of the bolt, they are seen to be in t li form of t^etli. For the par ticular ••mv>o«Jim»-nr i I ltistnt-».l in >igure 2 the leeth ure generally saw- tour h in shape, and each includes uil I JI extending between the i rest 22 of a given tooth and t h> r«eu 2h of an adjacent rontli. \n i in-1 i «i"*d <'irfac«.- 2b extend-. between the crest 22 of a tooth and the rent V-S • '(' tii-v te..tl:. The crests 22 of the s'-rrat ion* VO ar.- radiated as >t 2 t, for example uith a standard oi i-ompound radiu.- ot a -m'.'.. th founded blend, with the partitul.ir Op*' of radiu> select—I - 5 - 3 8 <11 dictated by u ilfitermin.itlon of locking nc' ioii di«.nired nml the degree of deformation of the workpiece uhu li can tm tolerated. The roots of the teeth arc defined by *t might lines originating from a point on the longitudinal n.*i* of the bolt. As a result, the width of earh sim ml ion increases as the distance from the axis of the bolt increases. In addition, the height of vail* 21 of each serration increases as the distance from the axis of the bolt increases.

Annular ring 18 is seen to be in the form of a continuous surface of substantial radial width. The term "siib.«t<int i;:i 1 " in describing annular ring 18 means a rir.(C of finite width in contrast to a sharp edge. The present invention may utilized without an annular ring if so desired especially in applications where the size of the bearing member of the fastener should be maintained as small .is possible*.

The radially outermost ends of the .-rests 22 of serrations 20 are contiguous to the innermost. «■ eminent of annular ring 18 and the crests 22 lie in .in imaginary surf.'ire which meets ring 18 along a rlrculsr line without forming n step or wall between thi s imaginary surface and the annul airing. As most clearly illustrated in Figure ■'*, the cr«-it« 22 lie in an imaginary sun ace which is fl C0flt1fHi9\JS, radidily inward extension of the bearing surface of tne annular ring i8. far the embodiment of the invention illustrated in Figures 2 and U, the surface of annular rin^j 18 contains extrusions or crests 22 and, as a result, the bearing surface of flange i6 is generally conical. With the b*arin<~ surface of fiance I'-so inclined relative to the Inngirudinal <t\i a Mi 3 8 112 annular ring will come Into contact with a workplece 29 only after the serrations 20 have contacted the workplece.

As the bolt 1s turned for installation in a workpiece in the direction of the arrow in Figure 2 and th9 underside of 5 flange 16 of the bolt bears against the workplace, cold flow of the workpiece material takes place as the workpiece is engaged by the Inclined surface of each serration. The cold flow material builds up behind each wall 21 of each serration, whereby resistance is created to rotation of the bolt in an 10 opposite direction. The extent of penetration of serrations 20 into the workpiece is controlled accurately to a major dogree by the surfaces of the radiused portions 23 and to a lesser extent by annular ring 18. Upon engagement of the workplece by the radiused segments 23, the smooth surfaces of the r«d Steadily increasing opposition to 15 segments produce /further penetration of the seri nt lunn by incicdsi the turning force required. The /nature of the workpiece material determines the extent of penetration of the serrations and whether the annular ring portion of the bearing surface will penetrate the workpiece and, if so, to what extent. 20 The location of annular ring 18 outside the serrations produces a desirable result because the serrations cau?o cold flow in the workpiece material and undesirable stress concentrations are created in the workpiece. However, with the serrations within annular ring 18, the ring is effective 25 in "captivating" these stress concentrations and preventing thera from extending beyond the area covered by l'lange lb. In contrast, a bolt having the annular ring within the serrations is not capable of limiting the effect of stress concentrations 3 8 11^ in the sane manner. The fact that crest 22 of each serration Ilea in a surface which Is a continuous extension of ring 18 ■•ana that even when ring 18 penetrates the workplece th<* problems, if any, due to stress concentrations are minimal since the change in shape of the workpiece surface Is gradual.

With reference now to Figure 3 it is seen that an alternative embodiment for the crests of the serrations is shown. In Figure 3 elements which are the same as in the embodiment of Figure 2 are numbered with the same reference numeral. Thus, the bearing surface of flange 16 includes an annular ring 18, a plurality of tooth-like serrationa 20 within ring 18 with each serration including a wall 21 extending between the crest 22 of a given tooth and the root 24 of an adjacent tooth.

In this embodiment the crests 22 are each formed radially extending flat or land 30 of finite width with the inclined surface 26 extending between the root 28 of one tooth to the trailing edge 32 of the flat 30 on the t:rest 22 of the next adjacent tooth. Preferably the flats 30 as well as the rocria 28 are defined by straight lines originating from a point on the longitudinal axis of the bolt and, as a result, tba width of each flat and the serration itself increases radially outwardly of the bolt longitudinal axis. Also, the height of wall 21 of each serration increases radially outwardly of the longitudinal axis of the bolt. Alternatively, the width of the flats could be made to decrease radially outwardly of the bolt longitudinal axis and/or the height of walla 21 could be made to decrease radislly outwardly of the 38442 bolt longitudinal axis.

In this embodiment the extent of penetration of the serrations and, hence, the locking a.-tion and the deformiition or "brinelling" of the workpiece, is accurately controlled to a major degree by the flats 30. Thus, mm the bolt ia turned for installation in tlio direction of the arrow in Figure 3 cold flow of the workpiece material r.<k<;s plan-as the workpiece is engaged by the inclined surface of each serration. The workpiece material subjected to onl.l flow builds up behind the wall 21 of each serration to i-icato a resistance to rotation of the bolt in the opposite direction. As rioted previously, the surface area of contact presented by the fiats 30 on the crests !.! of the serrations limits the extent of j»enr t rat i on of the serrations to preclude undo* i. rei1 and harmful "brinelUnR" of the workpiece.

Figure 5 shows another embodiment of .< !>o I i nim1 t o. t<-.| in accordance with the present invention. I'Jus err,do-) i <r.<-: 11 differs from the embodiment shown i ri Figure •'« i r. t ui t i •'»2 is normal to the longitudinal axis of the bolt and annul airing 38 is ft convex curve. The transition fnm ring to crest U2 is smooth so ;u not to cause undesiied stress* conccntrations.

Figure t> shows still another emt>ud i m.- it • b.> i • constructed in nrcord.incs with the picsetit i n> <-n. t • <,i;. ; h i > embodiment differs from the others c- .• i oil.- 1 i t-. . I i- that root ^8 is rurved •ath^r than h--ir.fr a I ■ t. .

Figure 7 showi still another i-mhocj 1 ner.» ni i. • constructed in a ccord.i n.-e with the rc-e^e:.» i • i ----- l i 'Mi- - 9 - 38132

Claims (1)

1. CLAIMS: 1. A vehicle body or pallet for use 111 tin- transport «»t" cylindrical objects, comprising a plurality of pair.-* of pivotallv-mounted platforms arranged so that each pair is. individually 5 movable from a first position in which a surface of m»e of the two platforms of that pair is copl.anar with a surfai<- of tlx; other platform of that pair to a second position in which said two surfaces are relatively inclined and between them provide a support for one of said cylindrical objects. 2. A vehicle body or pallet as claimed in Claim 1, including a flat rectangular framework in which are mounted said plurality of pairs of platforms. 3. A vehicle body or pallet as claimed in Claim 2, wherein one platform in each pair is located on one side of ih<- *5 longitudinal axis of the framework while the other platform in each pair is located on the opposite side of said longitudinal •t. A vehicle body or pallet as claimed in Claim >, wherein the pivot axes of all the plat, forms on said one side 'if the longitudinal axis are coincident, and wherein the pivot axes of 20 ail the platforms on said opposite side of the longitudinal axis are also coincident. 5- A vehicle body or pallet as claimed in Claim 4, wherein said pivot axes are equally s'-aced from said longitudinal axis. 6. A vehicle body or pallet as claimed in any of Claims 25 2 to S> wherein each platform is movable from said first position to said second position under the control of a pair of support arms, each pivotally attached at one end thereof to tlie platform. 7• A vehicle body or pallet as claimed in Claim <>, wherein each of said support arms is pivotally attached at the other end thereof to an axle carrying friction pads or wheels running on tracks extending transversely of the framework. S. A vehicle body or pallet as claimed iri Claim wherem the centre of 30 M - 38442 convex curve. Root 78 of each tooth in Figure 10 is curved contrast to the straight-1ine roots in Figures 8 and 9. In Figure II, crest 92 i-*» normal to the longitudinal axis of the nut and annular ring 98 forms a small anfe-tt> with the radial plane containing the crests. It is uImi understood that the nuts depicted may have radiused m rtnl* on the Crests as well. While both the embodiment of Figure 2 with radiused Crests and of Figure 3 with flats on the crests have been shown with the annular ring 18 on the bearing flange lb as disclosed in the aforesaid specifications it is contemplated that for certain applications the present invention may he utilised without an annular bearing surface such as annular ring 18. In the referred to patent, the annular ring provides the opposition to further penetration of the serrations into a workpiece and controls the extent of penetration when a fasteni'r having the described feature;* is installed in a workpiece. In addition, the Annular ri in the fastener disclosed in the referred to patents also captivates the stress concentrations in the workpiece and prevents them from spreading beyond the area covered by the fastener flange. The present invention relies upon the particular crest configuration, i.e., radiused crest or flat on the crest, to provide the major opposition to further penetration of the serrations into the workpiece and to control the extent of penetration of the serrations into the workpiece. Vherr: the present invention is utilized in conjunction with :ti, .mmil.ir j 8 i J 2 Dearmg ring, such as ""ire 1-3, tho rinq provides scne cortrol of penetration and also provides a stress captivating effect. However, where stress concentration in the workplace is not a concern then the self-locking fastener of the present specification may be utilized without a circumferential annular ring. While there have been described what are at present considered to be the preferred embodiments of this invention, it will be abvious to those skilled in the art that various changes and modifications may be wade therein without departing from the Invention and it is therefore aimed to cover .ill such changes and modifications as fall within tn.? scope of the invention as defined by the apoenaed clavis. 3 8 1 <1- Cl.A LMS 1. A self-locking fastener having a d-iving portion with a radial bearing surface, said bearing surface including a plurality of annularly disposed serrations 0f generally saw tooth Shape when viewed along a cylinder concentric with the longitudinal axis of said fastener, the crests of said serrations being Shaped to limit and control the extent of penetration of the serrations in said bearing surface of the fastener into a workpiece when the fastener is operatively engaged within said workpiece. 2. A self-locking fastener as defined in Claim 1 wherein the crest of each of said serrations includes a continuous radius formed thereon to provide a bearing surface to contact said workpiece and thereby limit nnd control the extent of penetration of the serrations into said workpiece. 3. A self-locking fastener as defined in Claim 1 vherein the crest of each of said serrations includes a flat of a finite widtn formed thereon to provide a bearing surface to contact said workpiece and thereby limit and control the extent of penetration of the serrations into said workpiece. . A self-locking fastener as defined in any preceding claim wherein said fastener includes an annular ring in the form - 13 - U S 1 1 12 of a bearing surface of substantial widtii radially >.«: t u ■ r ■! i > of said serrations ami wherein tin- crisis of sniri *>•: :\n ions lie in an imaginary surface which is ;« continuous nidi lily Inward extension of said annular J'lny bearing surface, 5 5. A self-iorkisu; fastener as cetinea in clair; 1 wnpreii: of said serrations inclu'^j a vail .'Xt<-nduif; b>-<w--,';s crest of the svrracion nn i th-.- ro,j< of .-m -i l j■ ,u ■ -:i and an inclined surface >*x t fiid : ng; h-"„v-n tftij ; n. 10 crest of said serration. 6. A self-locking l'astwi»r dff i ik-.I in " • -.in! "■>. wherein the cro>: of said serrations iru'jdes a flat of finite width formed t.ki0.*~con t r 15 provide a bearing surface :o ciitavr sr«:d workp: i • h* limit and control the #»xt^nt of pent* ratiMi •■>!' rh- «.>> : : into the workpioce. 7 . A sel f- lock ; :is f-t«* t - ■ i ; . ■ , 3 8 4 4 2 wherein said inclined surface extends between the root iind tin-leading edge of the flat on the crest of the serration .md said wall extends from the trailing edge of said flat to the rout of an adjacent serration. 8. A self-locking fastener as defined in Claim b or 7 wherein the roots and the flats on the crests of said serrations are defined by straight lines originating from the longitudinal axis of the fastener. 9. A self-locking fastener as defined in Claim ^ wlwifin the crests of said serrations are inclined relative to a plane normal to the longitudinal axis of said fastener. 10. A self-locking fastener ns defined in Claim t wherein the crests of said serrations are normal to said longitudinal axis of said fastener. 11. A self-locking fastener as defined in Claim 5 wh.-rein the crest of each of said serrations includes a continuous racius formed thereon to provide a bearing surface to contact said workpiece and thereby limit and control the extent of penetration of the serrations into said workpiece. 12. A self-locking fastener as defined in Claim 11 wherein the juncture between the inclined surface of a serration and the wall extending between that serration and the root of thc-next adjacent serration is provided with a radiusvd transition. 13- A self-locking fastener as defined in C1 i m ri whorcii. 3 8 11 said radial bearing surfai'i- is ;,roviil.-i| wt lii ,«n : my in the form of a continuous bearing -on)' sui>-i .mi - i i! radial width radially outv.trdly ot t.u.! -i •• r: .1 > : un - >:)■: wh- i • , the crests of said serrations ) i<> in mi : y -mi : •• 5 which is a continuous radially invard x t .-n*-1 on < -s.-iio .mm;! u ring bearing surface. Ik. A self-locking fastener as defined in .nn p i i-< I i n.; claim wherein said fastener is a bolt including a !>olr h*-«.l and a threaded shank extending from s.-ii-j head .in>i wiic; ,-in -,i:m 10 radial bearing surface is on th» workpiec-" contar! i :i/< -:vl •>*" said bolt head. 15- A self-locking faston»r ;t s d'-fin.-d am 1 to 13 wherein said fastcnr-r is a nut i n»-lud 11:;: t :uit t> 'i\ and an internally threaded bol t receiving aji-rt ;«-•> > l:c: ■ : r. 15 and wherein said radial bearing sm fact' on ^^i nut body about said bolt i «<-i» i v i rig <tpr: :ur;'. 16 . A self-lucking bol: constiu. >.*..! .ir:>! t : substantially as described herein %nd shown : r. < .i and U, Figure J, Figure 5« Figure 6 or Figure 7 of the 20 accompanying drawings. 17• A self-locking nut constructed and arrang-M substantially as described herein and shown in any one ot Figures 8,9» 10 and 11 of the accompanying drawing., D*t«d this 22nd day of February 1973. T0KK1NS i CO., Applicants' Agents. (signed) j, ? Dartmouth Rosa, DUBLIN 6.