Source: https://patents.google.com/patent/GB2120741A/en
Timestamp: 2018-05-23 17:49:01
Document Index: 283189012

Matched Legal Cases: ['art 46', 'art 48', 'arts 46', 'art 46', 'art 46', 'art 48', 'art 48', 'art 46']

GB2120741A - Blind rivets - Google Patents
Blind rivets Download PDF
GB2120741A
GB2120741A GB8215144A GB8215144A GB2120741A GB 2120741 A GB2120741 A GB 2120741A GB 8215144 A GB8215144 A GB 8215144A GB 8215144 A GB8215144 A GB 8215144A GB 2120741 A GB2120741 A GB 2120741A
GB8215144A
William David Bradley
A self-plugging blind rivet comprises an assembly of a break-stem mandrel 14 and a tubular body 12 having a head 18 and a shank 16, with a bore 20 throughout and counterbores 22, 26 at both the head and tail ends of the body. The part of the shank 16 intermediate between the tail counterbore 26 and the head 18 has three longitudinal struts 32 separated by slits 30. The mandrel 14 has a stem 40 which extends along the bore 20 and projects from the head end of the body, and an enlarged, circumferentially grooved mandrel head 42 attached to the stem 40 and disposed in the tail counterbore 26. The tail portion 24 of the shank 16 of the body 12 is crimped into the groove 50 of the mandrel head 42 to provide mutually intergaging abutment surfaces whereby, on pulling the mandrel stem 40, the mandrel head 42 moves the tail portion 24 towards the head 18 of the body 12, and collapses the intermediate part of the shank, bending the struts 32 outwardly to form a blind head. The mandrel head 42 then passes along the bore 20 until it can be deformed outwardly into the head counterbore 22 into locking engagement with the body 12. <IMAGE>
SPECIFICATION Self-plugging blind rivet This invention relates to a self-plugging blind rivet of the kind comprising a tubular rivet body having a shank, an enlarged head at one end of the shank, and a mandrel which is disposed in the bore of the rivet body and projects from the head end thereof and which is pulled relative to the body so as to first form a blind head and then to expand part of the shank between the head of the body and the blind head, the mandrel being then broken to leave a portion thereof plugging the bore of the body while the remainder is discarded.
Rivets of this general kind are well known and have been made in a variety of different forms in order to meet various specific requirements.
We have now devised a rivet of the kind referred to above, in which the portion of the mandrel which is left plugging the bore of the body after setting the rivet is positively locked in position during setting of the rivet so as to resist accidental displacement and loss, and which rivet is suitable, particularly although not exclusively for fastening together soft or frangible materials of which the thickness may vary.
According to the present invention, there is provided a self-plugging blind rivet comprising an assembly of a tubular rivet body and a mandrel, the rivet body having an elongate shank, a head at one end of the shank and a bore throughout the head and shank, the rivet body having a counterbore at the head end of the bore, and an annular locking shoulder facing towards the head end at the junction of the bore and head counterbore, the shank having a tail portion remote from the head, and a tail counterbore in the tail portion, the shank being of a length sufficient to extend entirely through members of a workpiece to be blind rivetted together so that the tail portion and part of the shank between the tail portion and the head of the body project from the workpiece on the blind side thereof which is remote from the head of the body, the mandrel having an elongate stem which extends through the bore of the tubular rivet body and projects from the head end thereof, and an elongate, generally cylindrical, radially enlarged head connected to the stem by a breakneck, the head of the mandrel being disposed in the tail counterbore and having a diameter greater than that of the bore of the tubular body, the mandrel head having at least one circumferential groove, and the tail portion of the shank having a deformation which projects into the or each groove so that the body and the mandrel provide mutually interengaging abutment surfaces in the groove or grooves such as to resist relative axial movement between the mandrel and the body, whereby, on pulling the mandrel stem, first the shank will be subjected to compressive force such as to cause radial enlargement of the projecting part of the shank between the tail end portion and the blind side of the workpiece, and then the mandrel head will be stripped out of interengagement with the tail portion and will pass along the bore in the part of the shank within the workpiece, thereby expanding the said part of the shank, the head of the mandrel having an integral locking means deformable into abutment with the locking shoulder.
The part of the shank between the tail end portion and the head of the body may be formed with a plurality of circumferentially spaces zones of weakness extending longitudinally of the shank to facilitate radial enlargement of the said projecting portion of the shank of the body.
The zones of weakness may be in the form of longitudinal slots or slits extending radially through the shank.
There may be a single groove in the head of the mandrel and said groove may be spaced from the breakneck by a distance at least as greater as the axial thickness of the head of the body.
There may be a plurality of grooves in the head of the mandrel, the tail portion of the body having a plurality of annular deformations each projecting into a groove of the mandrel head.
The, or each groove in the head of the mandrel may be shaped so that, when the mandrel and the body are moved axially relative to each other, the groove or grooves shear off the material of the body which projects into them.
The or each groove may be provided with an annular wall facing generally towards the stem and at a sufficiently steep angle to the axis of the mandrel to shear off the projecting deformation of the shank.
Embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which: Figures 1 and 2 are, respectively a sectional elevation of the body, and a side elevation of the mandrel for a blind rivet according to the invention, prior to assembly; Figure 3 is a section on the line Ill-Ill of Fig. 1; Figure 4 is a sectional elevation showing a blind rivet according to the invention positioned and ready to be set in a workpiece to be riveted, and showing part of a riveting tool for setting the blind rivet; Figures 5, 6, 7 and 8 are sectional elevations showing successive stages in the setting of the blind rivet.
A self-plugging blind rivet 10 consists of two parts, namely, a tubular rivet body 1 2 and a mandrel 14, which are assembled to gether to form a unitary structure.
The rivet body is made of aluminium alloy and has an elongate shank 1 6 and a radially enlarged head 1 8 formed integrally with the shank at one end (the "head end") of the body. The body has a bore 20 throughtout its length, the diameter of the bore being in creased at the head end by a head counter bore 22, and, in a portion 24 of the shank at the end remote from the head (the tail end) by a tail counterbore 26. The head counterbore is shorter than the thickness of the head and provides a locking shoulder 28 at the junction between the bore 20 and counterbore 22.
The locking shoulder faces towards the head end of the body.
The part of the shank between the head 1 8 and the tail portion 24 is hereinafter referred to as the "collapsible part" and has three longitudinal slits 30 spaced equiangularly around the shank. Each slit extends from the position closely adjacent to the head 1 8 to a position closely adjacent to the tail portion 24 which corresponds in length to the length of the tail counterbore 26. The slits are made as narrow as practicable in the circumferential sense, and serve to define between them three longitudinal struts 32 which are sepa rated from each other by the slits and which when the shank is subjected to axial compression, will bend outwardly, as will become apparent.
The underside of the head 1 8 which faces towards the tail end of the body is dished or undercut to leave a circumferential sealing lip 34 which, in co-operation with a compressible workpiece or accessory sealing washer, assits the formation of a seal between the rivet and a workpiece in which the rivet may be installed.
The mandrel 14 is of the breakstem type and is made of aluminium alloy. The mandrel comprises a head 42 which, after setting of the rivet serves to plug the bore of the body and is therefore hereinafter referred to as the plug 42, and an elongate stem 40 which is joined to the plug 42 by a breakneck 44.
The breakneck is the weakest part along the length of the mandrel so that, when the mandrel is subjected to tension, it will break at the breakneck rather then elsewhere. The stem 40 is a clearance fit in the bore 20 of the tubular body 12, and of appreciably greater length than the body 1 2.
The plug 42 comprises two principal parts, namely an externally cylindrical first part 46 immediately adjacent to the breakneck 44, and a main part 48 remote from the break- neck, and has, between the first and main parts 46, 48 a keyway 50 in the form of a circumferential flat-bottomed groove bounded on each side by annular walls 52, 54 substantially at right angles to the axis of the mandrel.
The first part 46 of the plug has an external diameter such as to be a clearance fit in the tail counterbore 26 of the body 1 2 and a transition fit in the bore within the collapsible part of the body.
A cylindrical cleavage 58 extends into the first part 46 of the plug in the longitudinal direction away from the breakneck, and towards but not as far as, the keyway 50. The cleavage has a diameter the same as or minutely greater than that of the stem 40, and differentiates a portion of the first part of the plug adjacent to the breakneck into a central cylindrical core 60 of substantially the same diameter as the stem 40, and a skirt 62 which peripherally surrounds the core 60, the skirt being integrally joined with the rest of the first part of the plug in the region further from the breakneck than the cleavage extends.It will already have been understood from the foregoing description that the external diameter of the first part of the head is appreciably greater than that of the stem, and it will therefore be appreciated that the skirt presents an annular face or step 64 which faces towards the stem 40 and which has major and minor diameters greater than that of the stem. The skirt is deformable, by means of a suitable riveting tool, to form an outwardly directed flange capable of abutting the locking shoulder 28 in the body, and thus provides locking means for locking the plug in the body of the rivet.
The main part 48 of the plug is elongate and is cylindrical throughout its length except for a slight radial enlargement at the end remote from the breakneck and which provides a circumferential abutment flange 68 having a diameter slightly greater than that of the tail counterbore 26 in the body 12, so that the flange 68, on entering the tail counterbore, interferes with tail portion 24 of the body. Save for the flange 68, the rest of the main part 48 has a diameter not only greater than that of the first part 46 but such as to be capable of appreciably expanding the bore 20, and yet to be a clearance fit in the tail counterbore 26.
The body and mandrel are assembled by inserting the stem of the mandrel into the tail counterbore and passing it along the bore until the annular step 64 abuts the shoulder formed at the transition between the bore 20 and the tail counterbore 26. In this condition the stem 40 of the mandrel projects from the head end of the body and the keyway 50 of the plug is within the tail counterbore 26 inside the tail portion 24. The tail portion 24 is then crimped locally in the region peripherally of the keyway 50 so as to deform the tail portion and produce a radially inwardly projecting ring 70 which extends into and substantially fills the circumferential keyway 50.
The interengagement between the ring 70 and the keyway 50 is believed to be capable alone of enduring substantially all the force required to cause axial collapse of the shank during setting of the rivet, although it is also believed that resistance to entry of the first part of the plug into the bore 20 in the collapsible part of the shank may also play a part in ensuring that the necessary force can be transmitted from the mandrel to the body for collapsing the shank.
It will be appreciated that the interengagement between the ring 70 and keyway 50 maintains the parts of the rivet in an assembled condition ready for use.
The use of the assembled rivet 10 to fasten together apertured workpiece members will now be described.
Thus, an apertured panel member 110 which may be of a soft or easily fractured material such as glass fibre reinforced plastics material may be fastened to another apertured member 11 2 which may, for example, be a metallic support member for the panel, by bringing the members together with their apertures in register and inserting the rivet through the apertures until the head 1 8 abuts the member nearer the operator, and the tailend portion 24 and at least a portion of the collapsible part of the shank projects beyond the further member of the workpiece.
The rivet can be set by means of a rivet setting tool of a known kind sold under the Registered Trade Mark "AVDEL" and comprising means (not shown) for gripping and pulling the part of the mandrel stem which projects from the head of the rivet body, and having an annular anvil 114 for abutting the head of the rivet and deforming the locking skirt. The tool is offered up to the river so that the stem 40 passes through the anvil 11 4 into engagement with the gripping and pulling means, and the anvil abuts the rivet head.
The tool is then operated to pull the mandrel axially relative to the rivet body, in a direction to draw the plug 42 towards the head 18 of the body.
Due to the interengagement between the ring 70 of the crimped tail portion 24 of the body and the keyway 50 of the plug, the tail portion 24 begins to move with the mandrel towards the rivet head 18, accompanied by an outward bending of the three struts 32, at a point generally half-way between the distal face (indicated by reference 11 6) of the panel 110 and the tail portion 24 of the rivet body (see Fig. 5). This movement of the tail portion 24 with the mandrel continues until the three struts are bent double and forced firmly into abutment with the distal face 116, as shown in Fig. 6, so as to consistute a blind head 118 of greater transverse dimension than the apertures of the workpieces.
At this stage, the force required to move the tail portion nearer to the head 1 8 increases abruptly, to the extent that, by applying sufficient force, the protruding ring 70 which is engaged in the keyway 50 is sheared off from the tail portion, and the plug is stripped out of engagement with the tail portion, as shown in Fig. 7.
The plug then moves through the blind head and into the part of the shank which extends within the thickness of the workpiece members, expanding the shank radially so that, in an aperture of suitable diameter in the workpiece, good hole-fill can be obtained.
Continued pulling of the mandrel by the tool eventually brings the plug into engagement with a projecting annular rim 1 20 which projects forwardly of the anvil into the had counterbore 22. The rim has an inclined front face which, as the plug is drawn towards it, engages the step 64 and progressively deforms the locking skirt 62 radially outwardly, away from the central core 60 of the plug and thereby forms a radially enlarged locking flange 1 22 which comes to lie parallel to or even in abutment with the locking shoulder 28, thereby constituting an obstacle to withdrawal of the plug from the body. Once the skirt is fully deformed, the force required to pull the mandrel further increases abruptly.
On applying sufficient further force, therefore, the breakneck fractures, leaving the plug 42 locked in the body, while the stem 40 becomes detached and can be discarded, as shown in Fig. 8.
The form of the body may be modified in various ways. In particular, instead of having three struts 32 there could be only two or a greater number, for example six, made by appropriately varying the number of slits. Furthermore, the material of the shank could be punched out to form slots. Alternatively, the shank could merely be formed with longitudinal shear lines or grooves so as to provide longitudinal weakening of the collapsible part of the shank such as to enable it, on being compressed axially, to split into a plurality of longitudinal struts which can be bent or bowed outwardly until doubled and thereby form a radially enlarged blind head.
The means by which, in the foregoing embodiment, the formation of a blind head is achieved during setting of the rivet, and by which the plug is enabled to become disengaged from the tail-end portion of the rivet body may also be modified. A number of suitable solutions have been proposed in the past in connection with pull-to-set self-plugging blind rivets. However, it is believed that the solution to this problem offered by the preferred embodiment offers advantages in that on the one hand it facilitates good control over the different forces required at different stages of the setting operation and on the other hand it enables a single size of rivet to be versatile in the range of thickness of workpiece (i.e. "grip range") which can be accommodated.
1. A self-plugging blind rivet comprising an assembly of a tubular rivet body and a mandrel, the rivet body having an elongate shank, a head at one end of the shank and a bore throughout the head and shank, the rivet body having a counterbore at the head end of the bore, and an annular locking shoulder facing towards the head end at the junction of the bore and head counterbore, the shank having a tail portion remote from the head, and a tail counterbore in the tail portion, the shank being of a length sufficient to extend entirely through members of a workpiece to be blind riveted together so that the tail portion and a part of the shank between the tail portion and the head of the body project from the workpiece on the blind side thereof which is remote from the head of the body, the mandrel having an elongate stem which extends through the bore of the tubular rivet body and projects from the head end thereof, and an elongate, generally cylindrical, radially enlarged head connected to the stem by a breakneck, the head of the mandrel being disposed in the tail counterbore and having a diameter greater than that of the bore of the tubular body, the mandrel head having at least one circumferential groove, and the tail portion of the shank having a projection which extends into the one groove so that the body and the mandrel provide mutually intergaging abutment surfaces in the groove such as to resist relatively axial movement between the mandrel and the body, whereby, on pulling the mandrel stem, first the shank will be subjected to compressive force such as to cause radial enlargement of the part of the shank which projects between the tail end portion and the blind side of the workpiece, and then the mandrel head will be stripped out of interengagement with tail portion and will pass along the bore in the part of the shank within the workpiece, thereby expanding the said part of the shank, the head of the mandrel having an integral locking means deformable into abutment with locking shoulder.
2. A self-plugging blind rivet substantially as hereinbefore described with reference to the accompanying drawings.
GB8215144A 1982-05-21 1982-05-21 Blind rivets Withdrawn GB2120741A (en)
GB8215144A GB2120741A (en) 1982-05-21 1982-05-21 Blind rivets
GB2120741A true true GB2120741A (en) 1983-12-07
ID=10530589
GB8215144A Withdrawn GB2120741A (en) 1982-05-21 1982-05-21 Blind rivets
GB (1) GB2120741A (en)
GB2147385A (en) * 1983-09-29 1985-05-09 Tucker Fasteners Ltd Blind rivets
GB2159595A (en) * 1984-05-30 1985-12-04 George Siebol Blind rivets
GB2160943A (en) * 1984-06-25 1986-01-02 Phillips Plastics Corp Expansion rivet assembly
FR2566855A1 (en) * 1984-06-28 1986-01-03 Phillips Plastics Corp Expandable riveting assembly
EP0168355A1 (en) * 1984-06-21 1986-01-15 TAC RIVETING SYSTEM di Oggionni Pier Giorgio &amp; C. s.a.s. A snap-shank blind rivet
FR2699617A1 (en) * 1992-12-21 1994-06-24 Simaf Stud insert with threaded element
GB2388063A (en) * 2002-04-23 2003-11-05 Emhart Llc Improved peel-type blind rivet
US7887273B2 (en) 2005-09-15 2011-02-15 Newfrey Llc Blind rivet and method
CN105545909A (en) * 2016-02-18 2016-05-04 航天精工股份有限公司 Core bar self-locking type blind rivet
GB1538872A (en) * 1975-04-01 1979-01-24 Avdel Ltd Blind rivet
FR2565303A1 (en) * 1984-05-30 1985-12-06 Siebol George Rivet comprises a lay-blind with crimping ankle automatically adjusting
GB2388063B (en) * 2002-04-23 2005-11-23 Emhart Llc Improved blind rivet
US6428255B1 (en) 2002-08-06 Blind rivet
US6036418A (en) 2000-03-14 Self-expanding blind fastener with mechanical lock
US4958971A (en) 1990-09-25 Break-stem blind rivet
US4789283A (en) 1988-12-06 Fluid-tight blind rivet
1984-09-26 WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)