CA1251664A - Blind rivet - Google Patents
Blind rivetInfo
- Publication number
- CA1251664A CA1251664A CA000470856A CA470856A CA1251664A CA 1251664 A CA1251664 A CA 1251664A CA 000470856 A CA000470856 A CA 000470856A CA 470856 A CA470856 A CA 470856A CA 1251664 A CA1251664 A CA 1251664A
- Authority
- CA
- Canada
- Prior art keywords
- nose
- shank
- sleeve
- ths
- tapered
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000463 material Substances 0.000 abstract description 3
- 210000001331 nose Anatomy 0.000 description 54
- 210000003128 head Anatomy 0.000 description 18
- 238000010276 construction Methods 0.000 description 3
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229920002430 Fibre-reinforced plastic Polymers 0.000 description 1
- 241000950314 Figura Species 0.000 description 1
- 241000700159 Rattus Species 0.000 description 1
- 244000166490 Tetrameles nudiflora Species 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 210000001699 lower leg Anatomy 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B19/00—Bolts without screw-thread; Pins, including deformable elements; Rivets
- F16B19/04—Rivets; Spigots or the like fastened by riveting
- F16B19/08—Hollow rivets; Multi-part rivets
- F16B19/10—Hollow rivets; Multi-part rivets fastened by expanding mechanically
- F16B19/1027—Multi-part rivets
- F16B19/1036—Blind rivets
- F16B19/1045—Blind rivets fastened by a pull - mandrel or the like
- F16B19/1063—Blind rivets fastened by a pull - mandrel or the like with a sleeve or collar sliding over the hollow rivet body during the pulling operation
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Dowels (AREA)
Abstract
ABSTRACT
BLIND FASTENER
A blind fastener for fastening an apertured workpiece of frangible material comprises a tubular body (12) having a shank (18) with a head (20) at one end and a tapering nose (22) at the other end, and means (14, 16) for forming a blind head by which the workpiece can be engaged at a position spaced radially from the shank (18) and clamped to the head (20).
The means for forming the blind head comprises a sleeve (16) and a headed bolt (14) whereby the sleeve (16) can be forced over the nose (22) of the body (12) and, thereby expanded.
A region (46) of the nose (22) immediately adjacent to the shank (18) is tapered at a sufficiently large angle to cause the leading portion of the sleeve to be permanently expanded to an internal diameter substantially greater than the external diameter of the shank, and the nose (22) has a less steeply tapered region (44) whereby the sleeve (16) is first radially expanded at a slower rate than by the region (46). The tapering regions (44, 46) can each be frusto conical or can be provided by a continuous concavely curved surface.
The bolt (14) is in screw-threaded engagement with the body (12) so that, on rotation of the bolt; the sleeve (16) will be forced over the nose (22).
(Figure 1)
BLIND FASTENER
A blind fastener for fastening an apertured workpiece of frangible material comprises a tubular body (12) having a shank (18) with a head (20) at one end and a tapering nose (22) at the other end, and means (14, 16) for forming a blind head by which the workpiece can be engaged at a position spaced radially from the shank (18) and clamped to the head (20).
The means for forming the blind head comprises a sleeve (16) and a headed bolt (14) whereby the sleeve (16) can be forced over the nose (22) of the body (12) and, thereby expanded.
A region (46) of the nose (22) immediately adjacent to the shank (18) is tapered at a sufficiently large angle to cause the leading portion of the sleeve to be permanently expanded to an internal diameter substantially greater than the external diameter of the shank, and the nose (22) has a less steeply tapered region (44) whereby the sleeve (16) is first radially expanded at a slower rate than by the region (46). The tapering regions (44, 46) can each be frusto conical or can be provided by a continuous concavely curved surface.
The bolt (14) is in screw-threaded engagement with the body (12) so that, on rotation of the bolt; the sleeve (16) will be forced over the nose (22).
(Figure 1)
Description
~ ;~r~ ~L6~
_IND FASTENER
This invantion ralatas to a blind ~astansr and particularly to a blind fastaner of tha kind eomprising a haadad body having a taparing nosa, and a tubular slaeve, and which is set by forcing the sleeve over the noss of tha body so as to radially axpand tha sleeve, tha expandad sleeva being sscured to the body and providing a blind head whieh can cooparata with ths hsaded body to fastan togather apartured mambers of a workpiace.
Tha invantion is conearned partieularly, although not ~xelu-sivaly, with a fastanar of the kind statad and which has a scraw-threadad, haadad bolt thraadadly angagad in a screw-threadad bora in the body, and which bolt can be caused to move along its axis by rotation ralativa to the body, wharaby tha head of tha bolt can ba rausad to mova towards tha body and to force tha tubular slsevs ov0r the taparing nosa so as to provida a blind haad.
Fastanars of tha lattar kind ara wall known and commareially available under the Ragisterad Trade Mark "~0-50ET", and are wiriely used in the aerospaee industry, partieularly for fastaning metallie shaats, sueh as shaats of aluminium alloy, to aach othar or to othar mambars, 9uch as struetural supporting mambars. Ganerally, such fasten3rs ara aminently satisfactory when the matarials to be fastenad ara at least moderately hard and not particularly frangibla or duetila, but thay are less satisfaetory whan tha work membar whieh P.~95 has to be angagsd by tha blind head is frangible.
In particular, same composita materials, such as carbon- and glass- fibre reinforced plastics matarials which ars now often employed in shaat form whers formarly metals wera used, havs desira-bls characteristics of low density and high tsnsile strength, butara frangible in that they have low compressive and shaar strengths, and are sometimes unabla to withstand the stresses to which thsy are subjsctsd whsn fastsned by conventional fastsnsrs of the kind referrsd to The main reason for ths unsatisfactory performancs of the con vsntional fastsnsrs of the kinds rsfsrred to in frangible matsrials is that the blind hsad providsd by the expandad slasve engagas only a small arsa of ths workpisce pariphsrally of the aperturs through which ths fastsnar 0xtands and immediately adjacsnt to ths sdga of ths matsrial bordering the apsrturs. This rssults in ths frangibla material bsing subjsct to localissd strassss which it is unabls to withstand.
This disadvantage of tha conventional fastsnars can ba attribu-tsd,at lsast in part,to tha fact that,while the external diamsters o~
2û both the sleevs and the part of the body which sxtends through ths aparture in ths workpiscs are necsssarily limited by ths diameter of the aperture, the nose of tha body is of simple frusto-conical shape, and the body is so shaped that, during setting of the fastener, the expanding sleeva tends to follow closely the contour of the parts of the body over which it is forced. Consequently, the P.295 ~5;~
maximum internal diameter of the expanded slaeve is not appreciably graater than tha diamatar of the part of the body which has been passed through the aperture in ths workpisce, and ths maximum exter-nal diameter of the expandsd slaeve is only greater than this by twice the wall thicknass oF the expanded sleeve. It is therefors virtually inevitable that the blind head thus provided by convsn-tional fastsners of the kind raferred to will engage the workpiecs in the sdgs rsgion closely bordering the aperturs and will lead to stressing of the matsrial in this region.
We havs now devised a fastensr of the general kind referred to in which tha body is so shaped as to expand part of the sleeve to form a blind head having an internal diametsr substantially grsater than the external diameter of tha part of the body which extends through the workpisce.
According to the present invention, thara is provided, a blind fastsnar comprising a tubular body having a praformad hsad for abutting one face of an aperturad workpiaca, an alongata shank joinzd to tha praforrnad head and abla to axtend through tha workpiaca so as to projact beyond the opposite face (herainaftar rafarrad to as thr~ blind faca) of tha workpiaca, and a nosa at tha end of the shank remote from the praformad haad, which nosa tapars externally from a diamatar tha same as that of tha shank to a smallar diamatar at the and ramota from tha shank, a ductila tubular slaava9 and means for forcing the slaeve ovar the tapering nosa and towards tha pre-formad haad so as to causs the slaev0 to be progressively expandedradially to form a blind haacl, wharain that external surface of tha nosa which oparates to cause axpansion of tha sleave is tapered P.295 ~ ~ 5'~.¢~
at a greater angle to the longitudinal axis of the body in a region adjacent to the shank than in a region nearer the smaller diameter end of the nose, said greater angle being sufficiently great that, when the sleeve is forced over the nose so that its leading end passes beyond the nose, the leading end of the sleeve continues to expand radially to a diameter substantially greater than the external diameter of the shank, and is thereby permanently deformed to an extent such that its internal diameter remains substantially greater than the external diameter of the shank.
The nose may be tapered through a plurality of frusto-conical portions.
The nose may have two frusto-conical portions of which the portion nearer the shank has a greater apical angle than that remote from the shank.
The nose may have a frusto-conical portion immediately adjacent the shank, and two or more further portions of which one may have an apical angle as great as that of the portion adjacent the shank provided that the nose has a further portion of smaller apical angle between the said one further portion and the portion adjacent the shank.
The nose may be tapered to a smaller diameter through a plurality of portions of which each one nearer the shank is more steeply tapered to a greater apical angle than il;s predecessor nearer the end of the nose remote from the shank.
The nose may have an external sùrface which forms, in the direc-tion longitudinally of the body, a concave curve providing increasingly steeply tapered portions nearer t:he shank.
P.295 r ~
Tha curve may ba continuous.
The curve may be an arc of a circle.
The curve may be an arc of an ellipse.
Spacific ambodiments of tha invention will now ba described by way af example and with rsferance to the accampanying drawings, in which:-Figura 1 i9 an axial section through a first fastener, inssrtedthrough a workpiace, bafore installation therein;
Figure 2 is similar to Figure 1 but shows the fastaner installed;
Figure 3 illustrates the shape of the nosa of the fastansr shank;
and Figure 4 is similar to Figure 3 but illustratas the shape of the nosa of a second fastener.
Referring first to Figura 1 of tha drawings, a blind fastensr 10 comprises thrae piecas, namely a tubular nut 12 which constitutes tha body of tha fastener, a bolt 14, and an sxpansible sleeve 16.
Tha nut 12 comprisas an alongate cylindrical shank 1~, an enlar-gad hexagonal hsad 20 at ona end of the shank, and a nose 22 at the and of the shank remote from the head 20. Tha nose 22 tapars to a smaller diameter away from tha head 20. The nut has a scraw-thraadad bora 24 which extends axially through the head, shank and nose.
~ D~
The bolt 14 comprisas an elorlgat~ stem 30 and an enlarged head 32 at ona end of the stem. The stam 30 is thraaded for sngagem2nt with the thread of the bore of the nut, and is longer than the combinad lengths of the nut 12 and the sleeve 16. Ths head 32 has substantially the same diameter as the shank of the nut. The stem of the bolt has a tail portion 40, remote from the haad 32, which is providad with a pair of diamatrically opposed flats 42 to facilitata gripping and rotating of the bolt. Th2 tail portion 40 is connected to the remain-der of the stem by a breakneck 34 at which the stem will break when subjected to a predet2rmined torque, thus enabling the tail portion 40 to be detached from the remainder of the bolt which remains as an assential part of tha installad fastaner.
The slseve 16 of this embodiment is a tubular cylinder having an extarnal diamater substantially the same as that of thz shank 18 of the nut, and has a smooth axial bora which is internally chamferd at the leading end to enabl2 the smaller diamet2r end of the nose 22 to enter easily ther2into. The diametar of th3 bors of the sle2v2 16 is sufficiently great to enabl2 the stem 30 of the bolt to ext2nd through the bora with slight claarance.
P.295 ~ ;~ 5 ~
Prior to use, the nut 12, bolt 14 and slsevs 16 ara assemblsd togsthsr, the stem of ths bolt bsing inserted through the sleeve and then scrswsd into ths snd of tha nut rsmots from ths hsxagonal head 20 until the tail portion 40 projscts from ths hsad snd of ths 5 nut. Ths asssmblsd fastsnsr can thsn bs inssrtsd into alignsd apsrturss 35, 36 in msmbsrs of a workpisce 37 which are to bs fastsnsd togethsr, so that ths shank 1~ sxtsnds through tha membsrs with tha hsxagonal head 20 abutting ths near face 3~ of the workpiscs, and the bolt head, slesvs, nose, and part of ths shank projsct bsyond ths 10 opposits or blind facs 39 of ths workpiscs.
Ths fastsnsr can then bs sst by gripping and rotating ths pro-jecting tail of tha bolt rslative to ths nut so as to cause the bolt hsad to mous axially towards ths nut and force ths slssvs on to and over ths noss of ths nut until th3 12ading snd of the sleevs clamps 15 the membsrs of ths workpisce tightly against ths hsad 20. At this stsgs the torque required to turn the bolt furthsr risss abruptly, and continusd rotating thsrsfors results in ths bolt brsaking at ths brsaknack, allowing ths tail portion to ba discardsd.
In accordancs with ths invsntion, ths noss 22 of ths nut of this 2û embodimant is so shapsd that, whan ths slasvs is forcsd towards tha head so that ths lsading snd of ths slesve passes ovsr and bsyond ths noss, ths leading snd of ths slssvs bscomss axpandsd to a diamstsr substantially grsatsr than that of ths shank of the nut.
Thus, rsfsrring mors particularly to Figurs 1 of tha drawings, 25 the noss 22 has a terminal frusto-conical portion 44 adjacent tha P.295 end of the nut remote from khe head 20, and a second frusto-conical por-tion 46 between the terminal portion 44 and the cylindrical shank 18. The terminal portion 44 extends over about two thirds of the axial length of the nose, and the second portion 46 extends over the remaining one third.
As illustrated in Figure 3, in this embodiment the external surface of the terminal frusto-conical portion 44 tapers towards an apical angle Of 40, while the external surface of the second frusto-conical portion 46 tapers more s-teeply, towards an apical angle of 7C. Thus, the apical angle of the portion 44 is substantially less than that of the portion 46, and the apical angle of the portion 46 is substantially greater than the apical angles of single-tapered noses of conventional fasteners of this general type, which are generally in the range of 30-42. The angle between the surfaces of the two portions should be greater than 90, and this embodiment is 165.
It can therefore be appreciated that, when the sleeve is forced over the nose during setting of the fastener, the leading end 48 of the sleeve first encounters -the gently tapering terminal portion 44 and, with comparative ease, is progressively expanded radially, with the expansion progressing along the length of the sleeve from i-ts leading end, so that the sleeve becomes flared. Subsequently, the already flared leading end of the sleeve encounters the more steeply tapering second portion 46 by which it is then expanded at a greater rate per unit of longitudinal travel through which i-t is moved by the bolt head. Eventually, the leading end of the sleeve reaches and passes the point of intersection between the second portion 46 of the nose and the cylindrical shank. As the shank 18 is cylindrical and has a constant diameter the same as the maximum diameter of the nose, the shank provides no internal support for the P.2~5 sleeve. Due to the taper of the second portion 46 of -the nose and notwithstanding the increasing hoop stress generated in the expanding sleeve, the leading end of the sleeve continues to move substantially in line with the surface of the portion 46 for a short distance and 5 thus continues further to expand radially until the hoop stress in the sleeve overcomes the tendency for the leading end to continue expanding.
The leading end then ceases to expand further.
We prefer that the leading portion of the sleeve which passes beyond the nose should assume a substantially cylindrical form in the 10 region adjacent to the leading end, while also having a diameter, inter-nallY,substantially greater than that of the shank, rather than that it should flare or taper towards the leading end. We therefore make the angle at which the second portion 46 meets the cylindri-cal shank 18 such that eventually, and before the leading end 43 will 15 mee-t the workpiece, the tendency of the sleeve to continue to expand a-t the same rate as when passing over -the surface of the second portion 46 will be substantially balanced by the hoop stress in the sleeve which simultaneously tends to cause the leading end of the sleeve to turn ra-dially inward towards the external surface o~ the shank. The precise 20 angle at which the second portion of the nose should meet the shank in order to balance the forces acting on the leading portion so that it will become cylindrical must be determined with regard to the length of the second portion and the physical properties, particularly the ducti-lity, elasticity and hardness, of the leading end of the sleeve. In 25 practice, we determine the angle empirically.
Continued rotation of -the bolt with respect to the nut causes the substantially cylindrical leading part of the sleeve 16 to advance, under the urging of the bolt head at the other end of the sleeve, until it abuts the blind face 39 of the workpiece and applies a force to it.
P.295 ~ f~ c~
This it does over an annular zona which is spacsd apart radially from ths 3dgs o~ the aparturs 36, so that strass is not applisd to tha workpiacs immsdiatsly adjacant this sdgs. The 3xpandsd slsavs provides a blind haad which~ togsthsr with ths prsformsd haad 20 of ths nut, clamps ths two membsrs of the workpiscs tightly togethsr.
Rssistancs to rotation of ths bolt incrsasss, and ths tail portion 40 breaks off, lsaving ths fastsnsr installed in ths workpiscs, as illustratsd in Figurs 2. Ths nut, bolt and sxpandsd slssvs ars effsctively sscured togsthsr by frictional sngagsmant. Ths distinct intsrnal chamfar on tha leading end of tha sle~va is no longer apparsnt, having bsen smoothsd out, by ths passage of tha slssvs along ths nut nosa.
Ths anglss chossn for this smbodimsnt and statsd abovs havs bsen found appropriate for a slssvs formsd of a stainlsss stasl spacifisd as A.I.S.I.304 (i.s. Amarican Iron and Stsal Instituts dasignation No.304). Gsnsrally, we havs found that ths apical angls of ths portion 46 should bs grr3ater than is usual for ths singls tapar ussd in convsntional fastsnsrs of this kind, and prsfsrably should not bs less than about 60 .
It is to be noted howsvsr) that if ths apical angla of tha portion 46 is too grsat, not only will sxcsssivs Forcs bs raquired to forcs the sl3svs ovsr this portion of ths noss, with ths attsndant risk of buckling ths slssvs or causing pramature braaking of ths breaknr3ck, but also ths hoop strassss in ths lsading snd of ths slssvs will not bs sufficisnt to prsvsnt continusd expansion of ths lsading 3nd of ths slssvs within a rsasonabls distancs of longitu-dinal travsl, with ths r3sult that ths lsading snd portion of ths slssvs will hava a flarsd shaps rathsr than a cylindrical shape.
This is not dssirabls.
P.295 ~ ~ e~ "~,r~
Instaad of only two differently tapered portions, the nosa may have a plurality of portions of which each ons nearer ths shank is more steeply tapered than its predacessor nearer the eno remote from ths hsad 20.
Thus, in a further embodirn3nt by way of an sxtr3me but practical example of such a construction~ a fastener generally similar to that of Figure 1 and illustrated fragmsntarily in Figure 4 has a nose 22 of which the external surface forms, in the direction longitudinally of the nut, a continuous concave curve which can be ragardsd as 1û being constituted by an infinite number of such increasingly staeply tapered portions.
In this embodiment, ths curve is formed as an arc of a circle of radius r of which the centre C is spaced forwardly of the end of the nose remote from the head of the nut by a short distance d1, and radially from the axis A of the nut by a distance which is greater than ths sum of the radii of the bore of the nut and the circle itself by a small distance d2.
The distance d1 is chosen preferably to be such that, at the point whsre the curved external surfacs of the nose meets the end face of the nose, a tangent to the curve meets ths end face at an angle greater than 90, so that there is an immediate increase in diameter of ths nose away from tha snd face.
The distance d2 is chosen prefsrably to be such that thers is a finite distance radially across the snd facs batwesn ths intsrnal surfacs of ths bors of ths nut and ths external surface of the nose, so that ths snd facs is not a kni~s-edge.
: P.295 The length of the radius of curvature r of the curved external surface of the nose is chosen so that the rate of change of diameter of the external surface of the nose is acceptable in relation to the rate of change in diameter which the sleeve can be forced to undergo, having regard to the size of the fastener, the ductility of -the sleeve, and the force available for deforming the sleeve.
In a specific example of this emdodiment, the shank of the nut has an external diameter of 7.9mm, the major diameter of the threaded bore is 5.6mm, and the minimum diameter of the nose is 5.9mm. The radial width of the end face of the nose is therefore, (5.9 - 5.6) 2mm =
0.15mm. The curvature of the external surface of the nose, in the longitudinal direction, is such that lt forms part of a circle having a radius of 5.7mm, and the distance dl, which is determined by the angle at which the external surface of the nose meets the end face, is l.Omm, and the distance d2, which is determined by the radial width of the end face and the value of dl, is slightly less than 0.15mm.
P.295 The effect of the curvingly tapered nose upon the sleeve, when the sleeve is forced on to and bayond the nose, is substantially the same as in the previous embodiment in that the leading end of the sleeve is expanded progressively and at a rate which increases as the leading end progresses from the tip of ths nose towards the shank.
As in the previous embodiment, the angle at which the leading end of the sleeve eventually leaves the nose, at the intersection of the nose and shank, is sufficient to cause the leading and to continue to expand radially before the increasing hoop stress in the lsading end of the sleeve appreciably restricts the radial expansion. As in the previous embodiment, ths hoop stress eventually restricts the expansion sufficiently to cause the part of the sleeve following tha leading end to assume a substantially cylindrical shape, surrounding but radially spaced from the external surface of the shank. The cylindrical leading part of the sleeve continues to advance, under tha urging of the bolt head at the other end of the sleeve, until it abuts the workpiece and thus constitutes a blind head which, in cooperation with the head of the nut, serves to fasten the members of the work-piece.
In contrast to the nose of the first embodiment, in which the taper is provided by two distinct frusto-conical portions of which the second has an apprsciably greater apex angle than tho first, or terminal, portion, the rats of change from small diarneter to maximum diameter of the nose of this embodiment is srnooth throughout the nose, and consequently tha amount of force required to force the sleeve over the nose does not increase suddenly. There is therefore less risk with this embodiment of a shock reaction causing thH breakneck to break prematurely.
P . ~95 $~ ~'~
In this embodimsnt, the concave curvatura corresponds in function and effact to the intarnally-angled relationship of the two frusto-conical portions of the first embodiment.
Instead of the concave curvature of the nosa being in the form of an arc of a circla, it could be in the form of an arc of an ellipsa without substantially altering its parformance, provid0d the criterion as to ths angle at which a line or tangsnt to the curve of tapar meets the external surface of the shank, and, desirably,the end face or tip of the nose~ is met Although, in the foregoing embodiments, the construction of the fastener is such that it can be sat by rotation of the bolt to urge the sleeve on to and over the nose by reason of the lead-screw effect achieved by the threaded interengagement between the nut and bolt, other constructions whereby the sleeve can be forced over the noss and, once it has been expanded and urged to fasten the members of a workpieca together, be secured to the body of the fastener, are possi-ble.
Thus, it is not necessary for the stem of the bolt and the bore of the nut to have interengaging scrsw-threads, but instead, the nut could be a haaded body having a shank, a tapered nose, and a smooth bore instead of a threaded bore, and the stem of the bolt could then ba pulled axially along the bore to cause tha bolt haad to urge tha sleeve over the nosa and to engage the workpiece, khe stem of the bolt being secured subsequently to the body so as to retain the sleeve in position in any suitable manner such as, for example, by being deform-ed to form an abutment able to cooperate with the body to prevent retraction of tha bolt and loss of the expanded sleeve.
P.295 ~ ~ r~
In embodiments of the invsntion in which the tapering nosa is formed of a plurality of frusto-conical portions, as for example in th0 embodiment of Figure 1, it is to be noted that the length of the frusto-conical portion naarest the shank has an influence on the extent to which the lsading end of the sleeve continues to expand radially after leaving the supporting surface of the nose. Thus, it has besn found that, within limits, tha greater the length of the frusto-conical portion nearest the shank, the greater the extent by which the diameter of the expanded sleeve will exceed the diameter of the shank.
Similarly, in ambodimants in which the nose prasents a roncavaly curved surface which meats the external surface of the shank, the radius of curvature of the curved surfaca will have an influence on the extent to which the slaeve continues to expand.
In a still furthsr ambodiment, the body of the fastener has a nose having a frusto conical portion adjacent to the shank, and naarar the tip of tha nose a further frusto-conical portion of which tha apical angle may ba as great as, or possibly even greatar than, that of the portion adjacant the shank, the two frusto-conical portions baing separated from each othar in tha axial diraction by an intermediata portion of smaller or zero apical angle.
In considering the magnitude of the angle formed in any embodi-ment between the longitudinal axis of the bolt and the surface of the tarrninal portion or the tangant to tha curvs as it approachas P.295 the end face or tip of the nose, any angle form~d by any bavelling or radiussing of the tip of the nosa for avoiding sharpness of the nose-tip or assisting its location in the bore of tha sleeve, can ba ignored.
Although we have disclosed some specific embodiments and dimensions, it will be appraciatsd that ths invention is not restricted thereto, as it is possible to make variations in the details of shape and dimensions. For instance when tha tapering nose is form3d of a plurality of frusto-conical portions, one frusto-conical portion may merge into tha next by means of a portion of suitably concavely curved profile.
P.295
_IND FASTENER
This invantion ralatas to a blind ~astansr and particularly to a blind fastaner of tha kind eomprising a haadad body having a taparing nosa, and a tubular slaeve, and which is set by forcing the sleeve over the noss of tha body so as to radially axpand tha sleeve, tha expandad sleeva being sscured to the body and providing a blind head whieh can cooparata with ths hsaded body to fastan togather apartured mambers of a workpiace.
Tha invantion is conearned partieularly, although not ~xelu-sivaly, with a fastanar of the kind statad and which has a scraw-threadad, haadad bolt thraadadly angagad in a screw-threadad bora in the body, and which bolt can be caused to move along its axis by rotation ralativa to the body, wharaby tha head of tha bolt can ba rausad to mova towards tha body and to force tha tubular slsevs ov0r the taparing nosa so as to provida a blind haad.
Fastanars of tha lattar kind ara wall known and commareially available under the Ragisterad Trade Mark "~0-50ET", and are wiriely used in the aerospaee industry, partieularly for fastaning metallie shaats, sueh as shaats of aluminium alloy, to aach othar or to othar mambars, 9uch as struetural supporting mambars. Ganerally, such fasten3rs ara aminently satisfactory when the matarials to be fastenad ara at least moderately hard and not particularly frangibla or duetila, but thay are less satisfaetory whan tha work membar whieh P.~95 has to be angagsd by tha blind head is frangible.
In particular, same composita materials, such as carbon- and glass- fibre reinforced plastics matarials which ars now often employed in shaat form whers formarly metals wera used, havs desira-bls characteristics of low density and high tsnsile strength, butara frangible in that they have low compressive and shaar strengths, and are sometimes unabla to withstand the stresses to which thsy are subjsctsd whsn fastsned by conventional fastsnsrs of the kind referrsd to The main reason for ths unsatisfactory performancs of the con vsntional fastsnsrs of the kinds rsfsrred to in frangible matsrials is that the blind hsad providsd by the expandad slasve engagas only a small arsa of ths workpisce pariphsrally of the aperturs through which ths fastsnar 0xtands and immediately adjacsnt to ths sdga of ths matsrial bordering the apsrturs. This rssults in ths frangibla material bsing subjsct to localissd strassss which it is unabls to withstand.
This disadvantage of tha conventional fastsnars can ba attribu-tsd,at lsast in part,to tha fact that,while the external diamsters o~
2û both the sleevs and the part of the body which sxtends through ths aparture in ths workpiscs are necsssarily limited by ths diameter of the aperture, the nose of tha body is of simple frusto-conical shape, and the body is so shaped that, during setting of the fastener, the expanding sleeva tends to follow closely the contour of the parts of the body over which it is forced. Consequently, the P.295 ~5;~
maximum internal diameter of the expanded slaeve is not appreciably graater than tha diamatar of the part of the body which has been passed through the aperture in ths workpisce, and ths maximum exter-nal diameter of the expandsd slaeve is only greater than this by twice the wall thicknass oF the expanded sleeve. It is therefors virtually inevitable that the blind head thus provided by convsn-tional fastsners of the kind raferred to will engage the workpiecs in the sdgs rsgion closely bordering the aperturs and will lead to stressing of the matsrial in this region.
We havs now devised a fastensr of the general kind referred to in which tha body is so shaped as to expand part of the sleeve to form a blind head having an internal diametsr substantially grsater than the external diameter of tha part of the body which extends through the workpisce.
According to the present invention, thara is provided, a blind fastsnar comprising a tubular body having a praformad hsad for abutting one face of an aperturad workpiaca, an alongata shank joinzd to tha praforrnad head and abla to axtend through tha workpiaca so as to projact beyond the opposite face (herainaftar rafarrad to as thr~ blind faca) of tha workpiaca, and a nosa at tha end of the shank remote from the praformad haad, which nosa tapars externally from a diamatar tha same as that of tha shank to a smallar diamatar at the and ramota from tha shank, a ductila tubular slaava9 and means for forcing the slaeve ovar the tapering nosa and towards tha pre-formad haad so as to causs the slaev0 to be progressively expandedradially to form a blind haacl, wharain that external surface of tha nosa which oparates to cause axpansion of tha sleave is tapered P.295 ~ ~ 5'~.¢~
at a greater angle to the longitudinal axis of the body in a region adjacent to the shank than in a region nearer the smaller diameter end of the nose, said greater angle being sufficiently great that, when the sleeve is forced over the nose so that its leading end passes beyond the nose, the leading end of the sleeve continues to expand radially to a diameter substantially greater than the external diameter of the shank, and is thereby permanently deformed to an extent such that its internal diameter remains substantially greater than the external diameter of the shank.
The nose may be tapered through a plurality of frusto-conical portions.
The nose may have two frusto-conical portions of which the portion nearer the shank has a greater apical angle than that remote from the shank.
The nose may have a frusto-conical portion immediately adjacent the shank, and two or more further portions of which one may have an apical angle as great as that of the portion adjacent the shank provided that the nose has a further portion of smaller apical angle between the said one further portion and the portion adjacent the shank.
The nose may be tapered to a smaller diameter through a plurality of portions of which each one nearer the shank is more steeply tapered to a greater apical angle than il;s predecessor nearer the end of the nose remote from the shank.
The nose may have an external sùrface which forms, in the direc-tion longitudinally of the body, a concave curve providing increasingly steeply tapered portions nearer t:he shank.
P.295 r ~
Tha curve may ba continuous.
The curve may be an arc of a circle.
The curve may be an arc of an ellipse.
Spacific ambodiments of tha invention will now ba described by way af example and with rsferance to the accampanying drawings, in which:-Figura 1 i9 an axial section through a first fastener, inssrtedthrough a workpiace, bafore installation therein;
Figure 2 is similar to Figure 1 but shows the fastaner installed;
Figure 3 illustrates the shape of the nosa of the fastansr shank;
and Figure 4 is similar to Figure 3 but illustratas the shape of the nosa of a second fastener.
Referring first to Figura 1 of tha drawings, a blind fastensr 10 comprises thrae piecas, namely a tubular nut 12 which constitutes tha body of tha fastener, a bolt 14, and an sxpansible sleeve 16.
Tha nut 12 comprisas an alongate cylindrical shank 1~, an enlar-gad hexagonal hsad 20 at ona end of the shank, and a nose 22 at the and of the shank remote from the head 20. Tha nose 22 tapars to a smaller diameter away from tha head 20. The nut has a scraw-thraadad bora 24 which extends axially through the head, shank and nose.
~ D~
The bolt 14 comprisas an elorlgat~ stem 30 and an enlarged head 32 at ona end of the stem. The stam 30 is thraaded for sngagem2nt with the thread of the bore of the nut, and is longer than the combinad lengths of the nut 12 and the sleeve 16. Ths head 32 has substantially the same diameter as the shank of the nut. The stem of the bolt has a tail portion 40, remote from the haad 32, which is providad with a pair of diamatrically opposed flats 42 to facilitata gripping and rotating of the bolt. Th2 tail portion 40 is connected to the remain-der of the stem by a breakneck 34 at which the stem will break when subjected to a predet2rmined torque, thus enabling the tail portion 40 to be detached from the remainder of the bolt which remains as an assential part of tha installad fastaner.
The slseve 16 of this embodiment is a tubular cylinder having an extarnal diamater substantially the same as that of thz shank 18 of the nut, and has a smooth axial bora which is internally chamferd at the leading end to enabl2 the smaller diamet2r end of the nose 22 to enter easily ther2into. The diametar of th3 bors of the sle2v2 16 is sufficiently great to enabl2 the stem 30 of the bolt to ext2nd through the bora with slight claarance.
P.295 ~ ;~ 5 ~
Prior to use, the nut 12, bolt 14 and slsevs 16 ara assemblsd togsthsr, the stem of ths bolt bsing inserted through the sleeve and then scrswsd into ths snd of tha nut rsmots from ths hsxagonal head 20 until the tail portion 40 projscts from ths hsad snd of ths 5 nut. Ths asssmblsd fastsnsr can thsn bs inssrtsd into alignsd apsrturss 35, 36 in msmbsrs of a workpisce 37 which are to bs fastsnsd togethsr, so that ths shank 1~ sxtsnds through tha membsrs with tha hsxagonal head 20 abutting ths near face 3~ of the workpiscs, and the bolt head, slesvs, nose, and part of ths shank projsct bsyond ths 10 opposits or blind facs 39 of ths workpiscs.
Ths fastsnsr can then bs sst by gripping and rotating ths pro-jecting tail of tha bolt rslative to ths nut so as to cause the bolt hsad to mous axially towards ths nut and force ths slssvs on to and over ths noss of ths nut until th3 12ading snd of the sleevs clamps 15 the membsrs of ths workpisce tightly against ths hsad 20. At this stsgs the torque required to turn the bolt furthsr risss abruptly, and continusd rotating thsrsfors results in ths bolt brsaking at ths brsaknack, allowing ths tail portion to ba discardsd.
In accordancs with ths invsntion, ths noss 22 of ths nut of this 2û embodimant is so shapsd that, whan ths slasvs is forcsd towards tha head so that ths lsading snd of ths slesve passes ovsr and bsyond ths noss, ths leading snd of ths slssvs bscomss axpandsd to a diamstsr substantially grsatsr than that of ths shank of the nut.
Thus, rsfsrring mors particularly to Figurs 1 of tha drawings, 25 the noss 22 has a terminal frusto-conical portion 44 adjacent tha P.295 end of the nut remote from khe head 20, and a second frusto-conical por-tion 46 between the terminal portion 44 and the cylindrical shank 18. The terminal portion 44 extends over about two thirds of the axial length of the nose, and the second portion 46 extends over the remaining one third.
As illustrated in Figure 3, in this embodiment the external surface of the terminal frusto-conical portion 44 tapers towards an apical angle Of 40, while the external surface of the second frusto-conical portion 46 tapers more s-teeply, towards an apical angle of 7C. Thus, the apical angle of the portion 44 is substantially less than that of the portion 46, and the apical angle of the portion 46 is substantially greater than the apical angles of single-tapered noses of conventional fasteners of this general type, which are generally in the range of 30-42. The angle between the surfaces of the two portions should be greater than 90, and this embodiment is 165.
It can therefore be appreciated that, when the sleeve is forced over the nose during setting of the fastener, the leading end 48 of the sleeve first encounters -the gently tapering terminal portion 44 and, with comparative ease, is progressively expanded radially, with the expansion progressing along the length of the sleeve from i-ts leading end, so that the sleeve becomes flared. Subsequently, the already flared leading end of the sleeve encounters the more steeply tapering second portion 46 by which it is then expanded at a greater rate per unit of longitudinal travel through which i-t is moved by the bolt head. Eventually, the leading end of the sleeve reaches and passes the point of intersection between the second portion 46 of the nose and the cylindrical shank. As the shank 18 is cylindrical and has a constant diameter the same as the maximum diameter of the nose, the shank provides no internal support for the P.2~5 sleeve. Due to the taper of the second portion 46 of -the nose and notwithstanding the increasing hoop stress generated in the expanding sleeve, the leading end of the sleeve continues to move substantially in line with the surface of the portion 46 for a short distance and 5 thus continues further to expand radially until the hoop stress in the sleeve overcomes the tendency for the leading end to continue expanding.
The leading end then ceases to expand further.
We prefer that the leading portion of the sleeve which passes beyond the nose should assume a substantially cylindrical form in the 10 region adjacent to the leading end, while also having a diameter, inter-nallY,substantially greater than that of the shank, rather than that it should flare or taper towards the leading end. We therefore make the angle at which the second portion 46 meets the cylindri-cal shank 18 such that eventually, and before the leading end 43 will 15 mee-t the workpiece, the tendency of the sleeve to continue to expand a-t the same rate as when passing over -the surface of the second portion 46 will be substantially balanced by the hoop stress in the sleeve which simultaneously tends to cause the leading end of the sleeve to turn ra-dially inward towards the external surface o~ the shank. The precise 20 angle at which the second portion of the nose should meet the shank in order to balance the forces acting on the leading portion so that it will become cylindrical must be determined with regard to the length of the second portion and the physical properties, particularly the ducti-lity, elasticity and hardness, of the leading end of the sleeve. In 25 practice, we determine the angle empirically.
Continued rotation of -the bolt with respect to the nut causes the substantially cylindrical leading part of the sleeve 16 to advance, under the urging of the bolt head at the other end of the sleeve, until it abuts the blind face 39 of the workpiece and applies a force to it.
P.295 ~ f~ c~
This it does over an annular zona which is spacsd apart radially from ths 3dgs o~ the aparturs 36, so that strass is not applisd to tha workpiacs immsdiatsly adjacant this sdgs. The 3xpandsd slsavs provides a blind haad which~ togsthsr with ths prsformsd haad 20 of ths nut, clamps ths two membsrs of the workpiscs tightly togethsr.
Rssistancs to rotation of ths bolt incrsasss, and ths tail portion 40 breaks off, lsaving ths fastsnsr installed in ths workpiscs, as illustratsd in Figurs 2. Ths nut, bolt and sxpandsd slssvs ars effsctively sscured togsthsr by frictional sngagsmant. Ths distinct intsrnal chamfar on tha leading end of tha sle~va is no longer apparsnt, having bsen smoothsd out, by ths passage of tha slssvs along ths nut nosa.
Ths anglss chossn for this smbodimsnt and statsd abovs havs bsen found appropriate for a slssvs formsd of a stainlsss stasl spacifisd as A.I.S.I.304 (i.s. Amarican Iron and Stsal Instituts dasignation No.304). Gsnsrally, we havs found that ths apical angls of ths portion 46 should bs grr3ater than is usual for ths singls tapar ussd in convsntional fastsnsrs of this kind, and prsfsrably should not bs less than about 60 .
It is to be noted howsvsr) that if ths apical angla of tha portion 46 is too grsat, not only will sxcsssivs Forcs bs raquired to forcs the sl3svs ovsr this portion of ths noss, with ths attsndant risk of buckling ths slssvs or causing pramature braaking of ths breaknr3ck, but also ths hoop strassss in ths lsading snd of ths slssvs will not bs sufficisnt to prsvsnt continusd expansion of ths lsading 3nd of ths slssvs within a rsasonabls distancs of longitu-dinal travsl, with ths r3sult that ths lsading snd portion of ths slssvs will hava a flarsd shaps rathsr than a cylindrical shape.
This is not dssirabls.
P.295 ~ ~ e~ "~,r~
Instaad of only two differently tapered portions, the nosa may have a plurality of portions of which each ons nearer ths shank is more steeply tapered than its predacessor nearer the eno remote from ths hsad 20.
Thus, in a further embodirn3nt by way of an sxtr3me but practical example of such a construction~ a fastener generally similar to that of Figure 1 and illustrated fragmsntarily in Figure 4 has a nose 22 of which the external surface forms, in the direction longitudinally of the nut, a continuous concave curve which can be ragardsd as 1û being constituted by an infinite number of such increasingly staeply tapered portions.
In this embodiment, ths curve is formed as an arc of a circle of radius r of which the centre C is spaced forwardly of the end of the nose remote from the head of the nut by a short distance d1, and radially from the axis A of the nut by a distance which is greater than ths sum of the radii of the bore of the nut and the circle itself by a small distance d2.
The distance d1 is chosen preferably to be such that, at the point whsre the curved external surfacs of the nose meets the end face of the nose, a tangent to the curve meets ths end face at an angle greater than 90, so that there is an immediate increase in diameter of ths nose away from tha snd face.
The distance d2 is chosen prefsrably to be such that thers is a finite distance radially across the snd facs batwesn ths intsrnal surfacs of ths bors of ths nut and ths external surface of the nose, so that ths snd facs is not a kni~s-edge.
: P.295 The length of the radius of curvature r of the curved external surface of the nose is chosen so that the rate of change of diameter of the external surface of the nose is acceptable in relation to the rate of change in diameter which the sleeve can be forced to undergo, having regard to the size of the fastener, the ductility of -the sleeve, and the force available for deforming the sleeve.
In a specific example of this emdodiment, the shank of the nut has an external diameter of 7.9mm, the major diameter of the threaded bore is 5.6mm, and the minimum diameter of the nose is 5.9mm. The radial width of the end face of the nose is therefore, (5.9 - 5.6) 2mm =
0.15mm. The curvature of the external surface of the nose, in the longitudinal direction, is such that lt forms part of a circle having a radius of 5.7mm, and the distance dl, which is determined by the angle at which the external surface of the nose meets the end face, is l.Omm, and the distance d2, which is determined by the radial width of the end face and the value of dl, is slightly less than 0.15mm.
P.295 The effect of the curvingly tapered nose upon the sleeve, when the sleeve is forced on to and bayond the nose, is substantially the same as in the previous embodiment in that the leading end of the sleeve is expanded progressively and at a rate which increases as the leading end progresses from the tip of ths nose towards the shank.
As in the previous embodiment, the angle at which the leading end of the sleeve eventually leaves the nose, at the intersection of the nose and shank, is sufficient to cause the leading and to continue to expand radially before the increasing hoop stress in the lsading end of the sleeve appreciably restricts the radial expansion. As in the previous embodiment, ths hoop stress eventually restricts the expansion sufficiently to cause the part of the sleeve following tha leading end to assume a substantially cylindrical shape, surrounding but radially spaced from the external surface of the shank. The cylindrical leading part of the sleeve continues to advance, under tha urging of the bolt head at the other end of the sleeve, until it abuts the workpiece and thus constitutes a blind head which, in cooperation with the head of the nut, serves to fasten the members of the work-piece.
In contrast to the nose of the first embodiment, in which the taper is provided by two distinct frusto-conical portions of which the second has an apprsciably greater apex angle than tho first, or terminal, portion, the rats of change from small diarneter to maximum diameter of the nose of this embodiment is srnooth throughout the nose, and consequently tha amount of force required to force the sleeve over the nose does not increase suddenly. There is therefore less risk with this embodiment of a shock reaction causing thH breakneck to break prematurely.
P . ~95 $~ ~'~
In this embodimsnt, the concave curvatura corresponds in function and effact to the intarnally-angled relationship of the two frusto-conical portions of the first embodiment.
Instead of the concave curvature of the nosa being in the form of an arc of a circla, it could be in the form of an arc of an ellipsa without substantially altering its parformance, provid0d the criterion as to ths angle at which a line or tangsnt to the curve of tapar meets the external surface of the shank, and, desirably,the end face or tip of the nose~ is met Although, in the foregoing embodiments, the construction of the fastener is such that it can be sat by rotation of the bolt to urge the sleeve on to and over the nose by reason of the lead-screw effect achieved by the threaded interengagement between the nut and bolt, other constructions whereby the sleeve can be forced over the noss and, once it has been expanded and urged to fasten the members of a workpieca together, be secured to the body of the fastener, are possi-ble.
Thus, it is not necessary for the stem of the bolt and the bore of the nut to have interengaging scrsw-threads, but instead, the nut could be a haaded body having a shank, a tapered nose, and a smooth bore instead of a threaded bore, and the stem of the bolt could then ba pulled axially along the bore to cause tha bolt haad to urge tha sleeve over the nosa and to engage the workpiece, khe stem of the bolt being secured subsequently to the body so as to retain the sleeve in position in any suitable manner such as, for example, by being deform-ed to form an abutment able to cooperate with the body to prevent retraction of tha bolt and loss of the expanded sleeve.
P.295 ~ ~ r~
In embodiments of the invsntion in which the tapering nosa is formed of a plurality of frusto-conical portions, as for example in th0 embodiment of Figure 1, it is to be noted that the length of the frusto-conical portion naarest the shank has an influence on the extent to which the lsading end of the sleeve continues to expand radially after leaving the supporting surface of the nose. Thus, it has besn found that, within limits, tha greater the length of the frusto-conical portion nearest the shank, the greater the extent by which the diameter of the expanded sleeve will exceed the diameter of the shank.
Similarly, in ambodimants in which the nose prasents a roncavaly curved surface which meats the external surface of the shank, the radius of curvature of the curved surfaca will have an influence on the extent to which the slaeve continues to expand.
In a still furthsr ambodiment, the body of the fastener has a nose having a frusto conical portion adjacent to the shank, and naarar the tip of tha nose a further frusto-conical portion of which tha apical angle may ba as great as, or possibly even greatar than, that of the portion adjacant the shank, the two frusto-conical portions baing separated from each othar in tha axial diraction by an intermediata portion of smaller or zero apical angle.
In considering the magnitude of the angle formed in any embodi-ment between the longitudinal axis of the bolt and the surface of the tarrninal portion or the tangant to tha curvs as it approachas P.295 the end face or tip of the nose, any angle form~d by any bavelling or radiussing of the tip of the nosa for avoiding sharpness of the nose-tip or assisting its location in the bore of tha sleeve, can ba ignored.
Although we have disclosed some specific embodiments and dimensions, it will be appraciatsd that ths invention is not restricted thereto, as it is possible to make variations in the details of shape and dimensions. For instance when tha tapering nose is form3d of a plurality of frusto-conical portions, one frusto-conical portion may merge into tha next by means of a portion of suitably concavely curved profile.
P.295
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A blind fastener comprising a tubular body having a preformed head for abutting one face of an apertured workpiece, an elongate shank joined to the preformed head and able to extend through the workpiece so as to project beyond the opposite face of the workpiece, and a nose at the end of the shank remote from the preformed head, which nose tapers externally from a diameter the same as that of the shank to a smaller diameter at the end remote from the shank, a ductile tubular sleeve, and means for forcing the sleeve over the tapering nose and towards the preformed head so as to cause the sleeve to be progressively expanded radially to form a blind head, wherein that external surface of the nose which operates to cause expansion of the sleeve is tapered at a greater angle to the longitudinal axis of the body in a region adjacent to the shank than in a region nearer the smaller diameter end of the nose, said greater angle being sufficiently great that, when the sleeve is forced over the nose so that its leading end passes the nose, the leading end of the sleeve continues to expand radially to a diameter substantially greater than the external diameter of the shank, and is thereby permanently deformed to an extent such that its internal diameter remains substantially greater than the external diameter of the shank.
2. A blind fastener according to Claim 1, wherein the nose is tapered through a plurality of frusto-conical portions.
3. A blind fastener according to either of Claims 1 or 2, wherein the nose has two frusto conical portions of which the portion nearer the shank has a greater apical angle than the portion remote from the shank.
4. A blind fastener according to Claim 1, wherein the nose is tapered to a smaller diameter through a plurality of portions, which may form a curve, of which each one nearer the shank is more steeply tapered to a greater apical angle than its predecessor nearer the end of the nose remote from the shank.
5. A blind fastener according to Claim 1, wherein the nose has an external surface which forms, in the direction longitudinally of the body, a continuous concave curve providing increasingly steeply tapered portions nearer the shank.
6. A blind fastener according to Claim 5, wherein the curve is an arc of a circle.
7. A blind fastener according to Claim 6, wherein the curve is an arc of an ellipse.
8. A blind fastener according to Claim 1, wherein the nose is tapered in the region immediately adjacent to the shank towards an apical angle of not less than 60°.
9. A blind fastener according to Claim 1, wherein the region of the nose immediately adjacent to the shank is tapered towards an apical angle of about 70°.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB848400345A GB8400345D0 (en) | 1984-01-06 | 1984-01-06 | Blind fastener |
| GB8400345 | 1984-01-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1251664A true CA1251664A (en) | 1989-03-28 |
Family
ID=10554659
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000470856A Expired CA1251664A (en) | 1984-01-06 | 1984-12-21 | Blind rivet |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS60159409A (en) |
| AU (1) | AU3719384A (en) |
| CA (1) | CA1251664A (en) |
| DE (1) | DE3446186A1 (en) |
| FR (1) | FR2557936B1 (en) |
| GB (2) | GB8400345D0 (en) |
| IT (1) | IT1181835B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2168122A (en) * | 1984-12-04 | 1986-06-11 | Avdel Ltd | Blind fastener |
| NO880310L (en) * | 1988-01-25 | 1989-07-26 | Defa Eltech A S | MOUNTING DEVICE FOR FITTING HEATING ELEMENTS IN A MOTOR HEATER TO A MOTOR BLOCK. |
| ES2030227T3 (en) * | 1988-03-17 | 1992-10-16 | The B.F. Goodrich Company | A BLIND BRA. |
| GB2347185A (en) * | 1999-02-04 | 2000-08-30 | Glynwed Engineered Products Li | Blind fastener |
| CN106246695A (en) * | 2016-08-12 | 2016-12-21 | 中国航空工业集团公司沈阳发动机设计研究所 | A kind of bindiny mechanism |
| CN108571510B (en) * | 2018-06-28 | 2020-08-18 | 同济大学 | Turnover type unilateral bolt fastener |
| CN113898654B (en) * | 2020-03-26 | 2023-02-03 | 重庆金海标准件有限公司 | Use method of bolt with changeable threaded area |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE7302121U (en) * | 1974-08-01 | Hahn W Mechanische Werkstaetten | Expanding socket connection, in particular for attaching fittings | |
| US3204331A (en) * | 1957-02-11 | 1965-09-07 | Brown Line Corp | Method of interconnecting members with a grooved pin and reformable collar |
| US3262353A (en) * | 1963-12-20 | 1966-07-26 | Standard Pressed Steel Co | Blind fastener |
| US3596948A (en) * | 1967-11-24 | 1971-08-03 | Vsi Corp | Blind fastener and blind fastener system |
| DE2300154A1 (en) * | 1973-01-03 | 1974-07-11 | Ver Baubeschlag Gretsch Co | FASTENING ELEMENT FOR HIGHER STRESSED COMPONENTS, IN PARTICULAR BUILDING FITTINGS |
| FR2329887A1 (en) * | 1975-10-29 | 1977-05-27 | Vsi Corp | BLIND BOLT FIXING DEVICE FOR LOW COMPRESSION RESISTANCE MATERIALS |
| US4364697A (en) * | 1977-12-12 | 1982-12-21 | Sps Technologies, Inc. | Blind fastener assembly |
| US4208943A (en) * | 1978-04-24 | 1980-06-24 | Huck Manufacturing Company | Multigrip fastener |
| GB2038978B (en) * | 1978-12-11 | 1983-02-09 | Avdel Ltd | Locking of blind fasteners |
| US4312613A (en) * | 1979-05-11 | 1982-01-26 | Binns Lloyd Sylvester | Blind rivet assembly |
| DE3242009A1 (en) * | 1981-11-18 | 1983-06-09 | Avdel Ltd | BLIND FASTENERS AND METHOD FOR THE PRODUCTION THEREOF |
-
1984
- 1984-01-06 GB GB848400345A patent/GB8400345D0/en active Pending
- 1984-12-18 DE DE19843446186 patent/DE3446186A1/en not_active Withdrawn
- 1984-12-19 GB GB08432125A patent/GB2152614B/en not_active Expired
- 1984-12-21 CA CA000470856A patent/CA1251664A/en not_active Expired
- 1984-12-28 AU AU37193/84A patent/AU3719384A/en not_active Abandoned
-
1985
- 1985-01-03 FR FR858500021A patent/FR2557936B1/en not_active Expired
- 1985-01-04 IT IT47519/85A patent/IT1181835B/en active
- 1985-01-07 JP JP60000250A patent/JPS60159409A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| AU3719384A (en) | 1985-07-11 |
| FR2557936A1 (en) | 1985-07-12 |
| IT8547519A0 (en) | 1985-01-04 |
| FR2557936B1 (en) | 1989-05-05 |
| GB8400345D0 (en) | 1984-02-08 |
| DE3446186A1 (en) | 1985-07-18 |
| GB2152614B (en) | 1987-02-18 |
| GB2152614A (en) | 1985-08-07 |
| IT8547519A1 (en) | 1986-07-04 |
| GB8432125D0 (en) | 1985-01-30 |
| JPS60159409A (en) | 1985-08-20 |
| IT1181835B (en) | 1987-09-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |