CA1096667A

CA1096667A - Blind fasteners

Info

Publication number: CA1096667A
Application number: CA305,484A
Authority: CA
Inventors: Richard D. Dixon; John H. Ruhl
Original assignee: Huck Manufacturing Co
Current assignee: Huck Manufacturing Co
Priority date: 1977-07-19
Filing date: 1978-06-14
Publication date: 1981-03-03
Also published as: IL54963A; SE7807009L; BE868926A; DE2829984C2; NL7807284A; SE439344B; JPS5439757A; FR2398210B1; BR7804559A; JPS62369B2; GB1604727A; DE2829984A1; FR2398210A1; IL54963A0

Abstract

ABSTRACT OF THE DISCLOSURE

A blind fastener of a selected metal in which uniform tensile values over a wide range of grips or material thicknesses in which the blind head is formed for different grips by the construction of a plu-rality of spaced annular ribs formed between spaced annular grooves in the head end of the pin which is pulled into the sleeve of the blind fastener.

Description

The present invention relates to a blind fastener for joinin~ together a plurality of workpieces.
One of the main difficulties in blind fasteners has been in providing a construc:tion which would assure uniform preload values for a varie-ty of grips or material thicknesses.
Illustrative of prior attempts are those disclosed in Schmitt U.S. Patent No. 3,702,088; Gapp U.S. Patent No.
3,148,578; Reynolds U.S. Patent No. 3,288,016; and Binns U.S. Patent No. 3,880,042.

The present invention resides in a blind fastener for joining together a plurality of workpeices over a wide range of grips, the fastener having a hollow tubular sleeve - provided with a preformed head at one end an open tubular extension at the other end, and a pin including a shank disposed within the tubular sleeve having pull means formed thereon extending beyond the preformed head on the sleeve and having a blind head forming portion extending beyond the other end of the sleeve. The blind head forming portion includes a plurality of spaced circumferentially extendin~
- ribs forming grooves therebetween constructed to engage and expand the other end of the sleeve to form the blind head.
Selected ones of the ribs are adapted to fold back successi~ely as they are moved through a plane defined by the rearward surface of the workpiece. At least one of the plurality of ribs remains in an unfolded condition proximate to the rear-ward surface after setting of the fastener and when the fastener is applied to workpieces of different grips within the wide range.

In one embodiment of the invention, the ribs are ~ r~ k cbr/J~

.. . . . . . . .
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~ . .' ' ' .
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adapted to fold bac~ successively in engagement wi-th the inner wall of the o-ther end as the fastener is se-t for different grips, -the grooves having a roo-t diameter less than the diameter of the pin shank and the last following rib of the head forming portion is of the greatest strength and the first leading rib is of a streng-th more resistant to deflection than the remaining ribs intermediate the last following rib and the first leading rib.
Depending upon the grip or material thickness with which the fastener is used, the ribs will progre~sively engage the end of the sleeve, form the blind head, and collapse or progressively fold back as the head is formed. At the end of the stroke, depending on the grip, pull pressure builds up to break the pin at the breakneck to complete setting of the fastener.
In the embodiment illustrated the pin and sleeve are preferably locked together as disclosed in the prior Reynolds U.S. Patent. Other known ways of providing the interlock may be used.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side elevational view of a fastener with parts sectioned and parts in elevation, embodying features of the present invention and in assembled relation with a pair of workpieces to be fastened together at nominal grip and with the fastener depicted prior to being set;
Figure 2 is a view similar to Figure 1 depicting the fastener at an early stage of its being set; ~.
Figure 3 is a view similar to Figure 2 at a further stage;
Figure 4 is a view similar to Figures 2 and 3 at the

2- .
cbr/J~
: . ~ :: . .

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i7 final set stage, with the pin tail broken off and with the pin and sleeve interlocked; and ,ff.~ 2a J;!~
cbr/JO

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Fi~lrc 5 is a view similar to Ii`ig-lre ~ with thc Iastc?ner finally set in worlipieces of maximum thickness or maxirn~lm grip.

DESCI~IPTION OF TIIE PI~E:F~RRI~D E:MBODIM13NT
AND BEST MODE: OF OPER~TION
. ._ .

Rererring to Figures 1 to 4, a fastener 10 is sho~rn in assembled relationship witll a pair of worlipieces 12 and :1~ to be joined together. The fastener 10 comprises a tubular sleeve 16 with a central bore 18 and a pin 20 extending theretlirough.
The sleeve 16 has a ~rusto-c-onlcally shaped head 22 at its forward or outside end ~vhich mates ~vith a co~lntersllnl; bore 24 in the outer ~ace of the worlipiece 1~. The sleeve 16 has a cylindrical body portion 26 ~vhich e~;tends rearwardl~ through and substantially beyond opening 2 in rear or inr.er workpiece 12~.
The bore 18 terminates adiacent the head 22 in an annular shoulder 30 ~Yhich provides material for interlocl;ing the pin 20 and the sleeve 16 and also provides a positive stop for lim;ting the movement of the pin 20 relative to the sleeve 16 as disclosed in the aforementioned -~Reynolds patent. `
The pin 20 DS assembled to the sleeve has a head end generaIly indicated at 32, a shanlc portion 3~, a loclc groove 3~iJ a breal;-necli groove 38, and a pull portion ~0 formed of annular pull grooves in the l~sual ~vay.
The present inventjon lics in the construct jon of tlle he.lcl c:lld 32 of thc pin 20, its arrangcmellt witl- rcspect to the inllCI` entl of thc slccvc ancl its functlon in fo~ming tllc llljn(l heacl for the acccmmc)clation , - , : : .

of different ~rips. ~ 7 The head end portion 32 comprises a plurality of annular ribs 42, 43 44 and 45 and terminating in an end rib 46.
Such ribs are formed by spaced annular grooves 4~ the root diameters of which are less than the diameter of the shank portion 34~ The ribs are also preferably shaped to have a pyramidal cross-sectional configuration tapering inwardly to have a base portion of greatest strength. This permits the controlled and progressive bending of the ribs as the fastener is set.
Although it is preferable to form the ribs by way of spaced annular grooves, an alternate way would be the formation of such ribs as a spiral thread. By controlling the depth, or root diameters, of the grooves 48 and/or the transverse width or configurations of the grooves, the cross-` sectional configuration of the ribs may be likewise varied to vary the resistance to deflection or bending of such ribs.
Thus, sleeve expansion or head formation may be varied for a desired design as well as load resistance at any portion of the installation cycle.
2C The rib 42 is stronger than ribs 43, 44 and 45 because the diameter of shank 34 is greater than the root diameter of adjacent groove 48. In the embodiment illustrated ribs 43, 44 and 45 have uniform resistance to bending. But variation in such bending resistance could be accomplished by varying the root diameters of grooves 48 The end rib 46 preferably has the greatest width dimension so that it is the strongest and not bendable at the end of the setting stroke.
Referring to Figure 2, the blind head has been formed and the first rib 42 collapsed or folded back. In Figure 3, at a further step in the setting cycle, the pin 10 has moved further into the sleeve and ribs 42 and 43 folded . . . . .
jb~ ~ 4 ~

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back or collapsed. In Figure 4~ the pin 10 has been moved to its complete set position, the interlock 30 has occurred, and the pin broken at the break-neck 38. For this grip, ribs 42 and 43 have folded back and rib 44 is beginning to fold back.
Referring to Figure 5, workpieces 13 and 15, corresponding to members 12 and :L4, are thicker and may be considered as illustrative of ma~imum grip. Thus, when finally set, ribs 42, 43, 44 and 45 have all collapsed back~7ardly.
While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is sUsceptable to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A blind fastener for joining together a plurality of workpieces over a wide range of grips comprising a hollow tubular sleeve having a preformed head at one end and an open tubular extension at the other end, a pin including a shank disposed within said tubular sleeve having pull means formed thereon extending beyond the preformed head on the sleeve and having a blind head forming portion extending beyond said other end of said sleeve, said blind head forming portion comprising a plurality of spaced circumferentially extending ribs forming grooves therebetween constructed to engage and expand said other end of said sleeve to form the blind head. selected ones of said ribs being adapted to fold back successively as they are moved through a plane defined by the rearward surface of said workpieces, at least one of said plurality of ribs remaining in an unfolded condition proximate to said rearward surface after setting of said fastener and when said fastener is applied to workpieces of different grips within said grip range.

2. A blind fastener according to Claim 1 ill which the number of annular ribs that collapse varies in accordance with variations in grip in which the fastener is employed.

3. A blind fastener according to Claim 2 in which the number of annular ribs that collapse increases with increase in grip in which the fastener is employed.

4. A blind fastener according to Claim 1 in which the grooves that form the ribs are of a smaller root diameter than the diameter of the pin shank proximate to the first of said ribs.

5, A blind fastener as set forth in Claim 1 in which said at least one of said plurality of ribs is positioned closely adjacent said .
rearward surface when said fastener is set so as to assist in retaining said other end of said sleeve in an expanded condition, said at least one of said plurality of ribs is operative to contribute to the tensile strength of said fastener.

6. A blind fastener as set forth in Claim 1, wherein said preformed head has a generally frusto-conical shape.

7. A blind fastener as set forth in Claim 1 wherein a last one of said ribs is of a strength selected to resist deflection and thereby inhibit setting of said fastener when it is applied to a grip larger than the maximum grip of said grip range.

8. A blind fastener as set forth in Claim 1 wherein the first of said ribs has a preselected strength sufficient to resist deflection while expanding that portion of said tubular extension extending beyond said rearward surface.

9. A blind fastener of a selected metal for joining together a plurality of workpieces over a wide range of grips comprising a hollow tubular sleeve having a preformed head at one end and an open tubular extension at the other end, a pin including a shank disposed within said tubular sleeve having pull means formed thereon extending beyond the preformed head on the sleeve and having a solid blind head forming portion extending beyond said other end of said sleeve, said blind head forming portion comprising a plurality of spaced annular ribs forming grooves therebetween constructed to engage and expand said other end of said sleeve to form the blind head and to old back successively in engagement with the inner wall of said other end as the fastener is set for different grips, said grooves having a root diameter less than the diameter of said pin shank and the last following rib of the head forming portion is of the greatest strength and the first leading rib is of a strength more resistant to deflection than the remaining ribs intermediate said last following rib and said first leading rib.

10. A blind fastener according to Claim 9 in which the remaining intermediate ribs are of uniform resistance to deflection.

11. A blind fastener for joining together a plurality of workpieces over a wide range of grips comprising a hollow tubular sleeve having a preformed head at one end and an open tubular extension at the other end, a pin including a shank disposed within said tubular sleeve having pull means formed thereon extending beyond the preformed head on the sleeve and having a blind head forming portion extending beyond said other end of said sleeve, said blind head forming portion comprising a plurality of spaced helical ribs forming grooves there-between constructed to engage and expand said other end of said sleeve, said plurality of ribs extending over a predetermined axial length of said pin, said predetermined length establishing a grip range for said fastener, selected one of said ribs being adapted to fold back successively as they are moved through an area of engagement between said expanded sleeve and said workpieces, at least one of said plurality of ribs remaining in an unfolded condition after setting of said fastener and being positioned closely adjacent said area of engagement whereby said at least one of said plurality of ribs is operative to contribute to the tensile strength of said fastener as set when said fastener is applied to workpieces of different `
grips within said grip range.

12. A blind fastener as set forth in Claim 11 wherein the first of said ribs has a preselected strength sufficient to resist deflection while expanding that portion of said tubular extension extending beyond said rearward surface.