CA2017421A1 - Hog ring fastener, tool and methods - Google Patents

Abstract

HOG RING FASTENER, TOOL AND METHODS
ABSTRACT OF THE DISCLOSURE
A hog ring fastener has a straight line base and legs each perpen-dicular to the base but offset at an angle to each other permitting the use of relatively inexpensive "C" points. A stick of the fasteners is generally channel shaped, with the legs and bases all angularly inclined to the longi-tudinal axis of the stick. The assembly of fasteners is made in a multiwire process by severing blanks and forming the legs at a bias to a line perpen-dicular to the wire direction. A tool and method for applying the fastener carries out two different deformation stages, one being a predeformation stage to incline the legs of the fastener inward to a preferred application position.

Description

2 ~

HOG ~NG FASTENER, TOOL AND METHODS
FIELD OF THE INVENTION
The present invention relates to improvements in hog ring fasteners an?~ fastener assemblies, to methods for makin8 hog ring fasteners and fas-5 tener assemblies, and to tools and methods for applying hog ring fasteners.
DESCRIPTION OF THE PRIOE~ ART
HogRin,,Fasteners Dsformable metal fasteners callecl ho8 rings are used in numerous " different applications for form~ng a rin8 or loop around workpieces of 10 various types. For ~xample, hog rings are used in the furniture indust:ry toattach upholstery material to a wire or rod suppoTt. One known hog ring ; fast:ener is a length of wire formed into aL c,urved, C-shape wlth pointed, convergi3lg legs. The fastener is deformed when applied by a tool to close and cross the legs and form a loop around a workpiece. Known hog ring 15 ~asteners are often assembled in strips or sticks and are dispensed in a toolons at a time from a magazine. U.S. patents 2,055,257 and 2,678,443 dis-close examples of C-shaped ho8 ring fasteners.
Hog ring fasteners are desiOoned w~th a structure or shap~ that pre- :
vents the opposed legs of the fastener from abutting and interfering with 20 one anothe.r as the fastener is formed into a loop or rin~ . This interference is undesirable because it can prevent the desired forming of the fastener to a loop and can cause jamming or wear and damage to a fastener ap-plication tool. The most common way to prevent interfsrence between the le?~s of a hog ring is to provide the opposed legs with points that are offset ._ ?

.. ..
,~

' 2 ~

- or oppositely bevelled. An example of this point configuration is found in U.S. patent 2,174,152, described at page 3, lines 32-44. Another known expedient is to provide an offset m the legs of a C-shaped fastener. An off-set in the legs or points is noted at column 3, lines 29-32 and seen in figure 1 of U.S. patent 2,678,443. Oppositely directed bevelled points and a tool for causing offset of the legs during application are disclosed m U.S.
patent 2,921,315.
A staple is a formed wire fastener having a U-shape with parallel !~ legs each peIpendicular to the base or bi8ht. Automated manufacturing and packaging equipment has been developed for economical fabrication and assembly of staples. Despite the cost advantage, staples have not suc-cessfully been employed as hog ring fasteners. One reason is that in-wardly inclined legs are preferred to parallel legs for application of the fas-tener. In addition, staples are most economically provided wi~h points by bevelling along planes perpendicular to the plane in which the base and legs of the fastener lie. Tbis type of point, called a "C" point, does not pro-vide an offset preventing interference between the legs when they are formed into a loop or ring. Although staples can be provided with offset points bevelled in the transverse direction, called a "D" point, this requires a more expensive manufacturing methocl.
In order to take advantage of some of the benefits of staple manu-facturing technology, formed wire hog ri~g fasteners with straight line bases and legs have been provided. A hog ring having this shape is dis-closed in U.S. patent 2,921,315. Like a conventional staple, the legs and base all lie in a common ilat plane. Unlike a conventional staple, the legs ara not perpendicular to the base, but rather are inclined toward one an-other in a trapezoid shape. This shape prevents the use of automated : pack~ing and handling equipment used with staples. To prevent inter-ference between the legs of this hog rin8 fastener as it is formed into a loop, the legs are provided with relatively expensive "D" points.
Methods of Manufacture Known ho8 ring fasteners are made by forming wire into the desired shape. Due to expense of formmg C-shaped fasteners, many hog ring fas-teners are now of the generally trapezoidal type referred to above. These fasteners can be made with equipment and methods similar to those used in the manufacture of some types of staples. However, the cost of manu-~ ' ' .

~2 ~

facture is increased by the necessity for inclining the legs of the fasteners toward one another and the necessity for oppositely directed bevels defining the oppositely oriented "D" points on the ends of the legs. A "D"
point cannot be manufactured economically with highly efficient multi-s wire fabrication equipment.
Many staple fasteners are :made in a multiwire process in which numerous wires are fed side by side in a flat plane to bonding, cutoff and forming stations. This is an economical and efficient process for produc-ing staples with a "C" point defined by bevelled surfaces perpendicular to the plane of the fastener. This type of point is formed by pinching off a blank fiom the flat array of adhered wires prior to formin8. The blank is rectangular and the legs are formed by bending the blanl~ to make right angle corners perpendicular to the sides of the blanl;. Because tllis manu-facturing method has been incapable of providing offsets in the points or legs of the fasteners, it has not been used for the manufactuIe of hog ring fasteners.
Application.Tools and Methods A known hog ring application tool includes a magazine from which ho~ rings are introduced one at a time into a pair of application jaws. The 20 - jaws hold ~he hog ring but do not deform it as they are advanced toward the nose of the tool. As the jaws reach the end of their path of movemellt, they are forced together by a mechanical linkage system to deform the hog ling into a loop in a single stage of defor:mation. Examples of tools of this type are disclosed in U.S. patents 2,174,152 and 2,678,443. U.S. patent : ~ 25 2,055,257 discloses a hog ril~.g application tool of t~is type in which the tool jaws are al~ranged to cause the legs of the fastener to be bent into an overlapping and offset position.
: Reference is made at column 1, beginning at line 29, of U.S. patent 2,921,315 to an unsatisfactory proposal involving a continuous deforma-~; 30 tioIl of a C-shaped hog ring while the jaws advance toward the nose of the tool. The purpose ascribed to this proposal is to tightly hold the fastener with the jaws. This proposal is characterized as objectionable because the full width of the spacing between the legs is not maintained.

7~

SU~fMARY OF THE INVENTION
One priIIcipal object of the present invention is to provide an im-proved hog ring fastener with legs lying in parallel planes in order to enjoy the benefits of existing staple making and handling equipment while avoiding the problem of interference between the fastener legs as the fas-tener is formed into a loop. Other objects are to provide a hog ring fas-tener that uses inexpensive "C" points and to provide an assembly of hog ring fasteners and a method for making the assembly with multiwire man-ufacturing equipment. Another object of the present invention is to pTO-vide an improved tool and method for applying hog rin~ fasteners using fasteners with legs in parallel planes and presenting fasteners to a work-piece with the legs inclined toward one another.
In brief, the objects and advantages of one aspect of the present in-vention are achieved by providing a hog ring fastener that is a length of wire having a central segment defining a base lying in a straight line and a pair of end segments defining legs at opposite ends of the base. The legs ;, lie in spaced apart planes that are parallel to one another and perpendicu lar to the base. In accordance with the present invention, the legs are an-; gularly offset fIom one another.
In accordance with another aspect of the present invention, an as-sembly of hog ring fasteners is an adhered stick of similar hog ring fasten-ers each being generally of a U-shape and having a base and a pair of legs~
The bases lie in a first plane and the legs lie in second and third planes.
The second and third planes are parallel to one another and aTe perpqn-dicular to ths first plane In accordance .with the present invention, jthe ~; legs in the first plane are angularly offset from the legs in the second . ~ plane.
The present invention also provides a method of making assemblies of hog ring fasteners by advancing numerous wires in parallel side by side 30 relation in a flat planar arTay and adher~s the wires to one another.
Blanks are severed from an end Qf the array, each bl~k including numer-ous side by side wire segments of equal length extendin~s parallel to one another in a first direction. The blank is bent along two bending lines to form a U-shaped stick of hog Iing fasteners. In accoTdance with the I, 35 method of this inven~ion, the severing step includes cutting the wiTes~
.. ~ . , i, ` !
, r ::
- ' ' ', . ' , ' ~. ' ;

2 ~

along a cutting line inclined by a bias angle to a perpendicular to the first direction and the bending lines are parallel to the cutting line.
Another aspect of the present invention relates to a method for ap-plying a generally U-shaped hog rinO fastener having a base and two le"s 5 lying in planes parallel to one another and perpendicular to the base. Th method includes aligning the fastener with a fastener application region and carrying out a first deformation of the fastener after the alignment step to incline the legs of the fastener toward one another while leaving a gap between the ends of the legs. The fastener is advanced to the application 10 region after the first deformation step and the gap is maintained during the advancing step. A second deformation step is carried out at the applica-tion region to form the fastener into a loop.
In brief, a hog ring application tool in accordance with the present invention includes a jaw set with a pair of normally open, pivotally 15 mounted jaws. The jaw set is movable in a drive stroke from a rest posi-tion to a fastener application region and the jaws are movable relative to one another in a closing movement. Means ale provided for introducing a hog ring into the jaws A linkage means is connected between a drive means and the jaw set for moving the jaw set in the drive stroke. Stop 20 means stops the jaw set at the fastener application region at the end of the drive stToke. The linlsage means includes means for closing the jaws in re-sponse to stopping the jaw set in order to form the hog ring into a loop.
Cam means is engaOed by the linlcage means for forcing the jaws partly closed only during a first portion of the drive stroke to predeform the hog 25 ring and for perrnitting further movement of the jaw set in the drive stroke while preventing further closing of the jaws.
BRIEF DESCRIPIION OF THE DRAWINGS
The present invention together with the above and other objects and advantages may best be unclerstood from the following detailed descrip-;
30 tion of the embodiment of the invention illustrated in the draw~ngs, wherein:
FIG. 1 is a side elevational view of an assembly of fasteners in ac-cordance with the present invention;
FIG. 2 is a bottom view of the assembly of fasteners of FI~. 1;
:
!

r ~ :

: , : , :' .-.: :

FIG. 3 is a front elevational viaw of a single fastener of the assQmbly of FIG. 1, taken g,enerally from the line 3-3 of FIG. 1 but taken from a plane parallel to the base o:E the fastener;
FIG. 4 is a side elevational view of the fastener, taken from the line 5 4-4 of FIG. 3;
FIG. 5 is a view similar to FIG. 3 illustrating the fastener following a first stage of deformation in a method o applying the fastener in accor-dance with the present invention;
FIG. 6 is a view similar to FIG. 5 illustrating the fastener following 10 the final stage of deformation in a method of applyin~g the fastener in ac-corclance with the present invention;
FIG. 7 is a schematic and diag,rammLatic view illnstrating steps in a method of manufacturing the fas~ener assembly of FIGS. 1 and 2 in accor-dance with the present invention;
FIG. 8 is a fragmentary, top plan view illustrating part of the . method of manufacturing the fastener assembly;
FIG. 9 is a side elevational view of a hog ring application tool em-hodying features of the present invention;
.~ FIG. 10 is a ~ront elevational view of the tool of FIG. 9;
FI&. 11 is a fragmentary top view of the tool of FIG. 9 illustrating :~ the be~o,inning of a hog ring application clrive stroke;
FIG. 12 is a view similar to FIG. 11 illustrating an intermediate part - ~ ~ of a hog rin~ application drive stroke; and ~ : FIG. 13 is a view similar to FIGS. 11 and 12 illustrating the conclu- :
:; ~ 25 sion of a hog~ring application d~ive stroke.
DETAILED DESClRIPTION DF THE: PREFER~RED EMBODIMENT
In the clrawm~s, FIGS. 1 and 2 illustrate an assembly generally designated as 20~ of a series of similar fasteners 22 constructed in accor dance with the principles of the present invention. As seen in FIGS. 3 and . 30 4, each fastener 22 is a length of wire formed generally in a U-shape and includes a base 24 and a pair of legs 26 each having an end 28. Fastener 22 is used to form a ring or loop aro~md a workpiece and is the type of a fastener known as a hog ring.

.

' 7~2~

- FIGS. 3 - 6 show how the faste.ner is deformed during its application into a loop or ring shape. The initial shape of a single fastener 22 is seen in FIG. 3. In this initial shape, the legs 26 lie in planes that are parallel toone another and perpendicular to the base 24. During the method of ap-5 plying the fastener according to the present invention, the fastener is par-tially deformed or predeformed in a first stage of deformation as seen in FIG. 5. In this first stage, the base 24 is partly bent or curved or bowed at a ce:utral region 30. As a result, the legs 26 are angled slightly toward one another. This inward angle facilitates proper engagement of the fastener 10 22 with a workpiece.
Following the first stage of deformation, a second and final stage of deformation takes place and the result is seen in FIG. 6. Region 30 is fur-ther deformed by bending, curving or bowing. The legs 26 cross or over-lap one another at an intersection region 32. A loop or ring 34 is defined 15 by the deformed base 24 including region 30 and by the inner segments of the legs 26.
As the fastener 22 is deformed to make the loop 34, it is important ~;` to prevent the ends 28 of the legs 26 from abutting against and interfering with each other. In accordance with the present in~ention, interference 20 between the ends 28 is avoided in the design of the fastener 22 by an angu-lar offset between the legs 26 seen best in FIG. 4. While the legs 26 lie in parallel planes, the legs 26 are not parallel to one another. Instead, each leg 26 extends from the base 24 at a slightly different angle. The of~set an-gle between the legs 26 is large enough to assure that the end 28 of each 25 leg 26 passes freely across the opposite leg during deformation of the fas-tener 22. The offset angle is small enough so that when the loop 34 is formed, the legs 26 either contact one another or are close together at the intersec~ion region 32. If the gap or spacing between the legs 26 at inter-section 22 is too large, certain types of workpiece material such as fine 30 wires, fabric fibers or the like could escape from the loop 34.
The optimum size of the offset angle depends on the dimensions of the fastener 22 and the wire from which it is made. The presently pre-ferred range of offset angles is from about two degrees to abo~t ten degrees and the presently preferred offset angle is about five degrees.
One aspect of the present i~vention is a method for mal~ing the fas-tener 22 and the fastener assembly 20. This method is indicated diagram-,, .
O
, 2 ~

matically in FIG. 7 and also partially in FIG. 8. Preferably a conventional multiwire staple manufacturing process is modified in accordance with the pr~ciples of this invention to make the assembly 20 of fasteners 22.
In t~is method, a number of individual discrete wires 36 are fed from a source OI supply (not sho~vn) in a flat, planar, side-by-side array.
The arTay of wires 36 moves through an application station 38 where an adhesive or binder, usually in liquid form, is applied to the alTay. Then the adhesive or binder is dried or cured. A drying or curing station 40 is provided for drying or curing the adhesive by the application of heat, air or the like. Depending on the material used, air drying may be emplo~ed.
At this point in the fabrication method, each wire 36 is adhe~ed to the ad-jacent w~re or wires 36 to form a flat planar web or strip of wires.
A cutoff station including cutoff blades or tools 42 and 44 severs a blanl~ 46 from the end of the adhered wires 36. Instead of ~he conven-tional practice in which wires are severed along a line perpendicular to their length, the tools 42 and 44 a~e arranged at a bias an~le 48 (FIG. 8) offset from the perpendicular. This bias angle deternLines the leg offset angle of each fastener 22. The side edges of the blank 46 aTe defined by ; and coincide with the direction or length of the wires 36. The ends of the blank a:r8 parallel to one another and are angularly offset from a line per-pendicular to the side edges by the bias angle 48. In the conventional `I multiwire process, a rectangular blank is severed at a cutoff station. In the method of the prese~t invention, the blank is a non~ectangular par-allelo~am with opposed corners defined alternately by ninety degrees ; 25 plus and minus the bias angle 48.
Blank 48 is conveyed to a form~ng station including cooperating fo~ning tools 50 and 52 that are closed over the blanlc to shape the blan~
i~to the fastener assembly 20. In this forming operation, comers 54 of the asseInbly result where the le~s 2~ are deformed to extend fIom the basesl 30 24. After this forming opera~ion, all of the legs 26 are of equal length and are parallel to one another. A~l of the legs 26 at one side of the assembly 20 lie in a ~st flat plane, all of the legs at the opposite side of the assem-bly 20 lie in a second ~lat plane and all of the bases 24 lie in a third flat plane. The first and second planes are parallel to each other and the ~st 35 and second planes are perpendicular to the t~i~d plane. The corners 54;
are somewhat rounded or gradual and constitute right angle corners re~

.,, ~

, 2 ~

spectively between the first and third planes and between the second and third planes.
In a conventional multiwire fabrication process, the forming tooling is arranged so that comers are formed lying along lines perpendicular to s the directions of the individual wires. In contrast, in accordance with the present invention and as seen in FIG. 8, the tooling is arranged so that the corners extend along lines that are angularly offset from a line perpendicu-lar to the wire direction by the bias angle 48! The tooling edges are paral-lel to the front and rear edges of the blank 46 and in the assembly 20 the corners 54 are parallel to the fastener ends 28 and all of the legs 26 are of the same length.
U~like conventional fastener assemblies made by known mllltiwire fabrication techniques, the assembly 20 does not occupy a rectangular, right cylindlical volume. Instead, the ends of the assembly are canted or biased by the bias angle 48. The angular offset betwee~ the side edges of the blank 46 and the forIIung tools 50 and 52 causes the legs 26 to extend at diffe~ent angles from the bases 24 to provide each individual fastener 22 with the offset angle seen in FI&. 4. The assembly 20 is generally channel shaped with a longitudinal axis extending along the length of the assem-bly. Each leg 26 and each base 24 is angularly inclined with respect to this longitudinal axis.
The fastener 22 and assembly 20 have important advantages that are not achieved with known hog r~ng fasteners. One of these advantages is that they can be economically made with modified conventional multi-wi~e staple m~king equipment. Moreover, assemblies 20 can be handled and packaged at low cost by existing equipment used fo~ other fasteners.
Because the planes of the legs ~6 of the assemblies 20 a~e parallel, the as-semblies can be internested in dense and efficient packaging arrays.
Another important ad~antage is that the ends 28 of the fasteners 22 are provided with a poin-ts by the cutoff tools 42 and 44 as the wires 36 are pinched between the tools. Many known hog ring fasteners with parallel or symmetrical legs use oppositely direc-ted "D" poi~ts to pravent interfer-ence between fastener legs when the fastener is formed into a loop or ring.
With this hlowll arrangement, the points on the opposed leg of a sin~le ~stener are defined by oppositely beveled planes parallel to the fastener base. Such "I)" points cannot be formed by simple cuto~ tooling in a mul-. , .,, ~

tiwire process. As a practical matter, the "D" points must be made by a more expensive process in which one wire at a time is severed and formed by cutoff tooling.
The points of -the fasteners 22 are of a different type known as "C"
5 points, and are defined by two illtersecting inclined planes runnirlg along the length of the leading and trailing edges of the blank 46 and thus run-ning along the length of the formed assembly 20. The bevels lie in planes that are ~ot parallel to the fastener bases 24. Alternatively, if one of the cutoff tools 42 or 44 is blunt instead of sharp, points may be defined by 0 single planes along either the inside or the outside of the fastener le~s 26.
Using any of the alternative "C" points, forming of the ends 28 into points is accomplished easily and economically during the modified multiwire fabrication process of the present invention simply by pinc~ing off the ends of the wires 36.
Referring now to FIGS. g and 10 there is illustrated a hog ring ap-plication tool generally designated as 60 and constructed in accordance with the present invention. A housing 62 includes a handle portion 64 . and a head portion 66 enclosing a pneumatically operated drive piston 68 normally located at the illustrated standby or rest position. A tri~3er 70 is depressed by the user to admit pressurized fluid from an inlet fitting 72 to the rear of the piston 68 to operate the tool 60 in a drive stroke for applica-tion of one hog ring fastener 22.
A track member 7aS is supported on a front cover 75 of housing 62 and extends forward to a fastener application region 76 where a fastener ` 25 22 is applied to a workpiece (not showII). A set 78 of jaws is supported on track member 74 for reciprocal movement between a normal standby rest position (FIGS 9-11) and a fastener application position (FIG. 13) at the end of a d~ive stroke. Jaw set 78 includes a pair of jaws 80 and 82 movable relative to one another between an open position (FIG. 11) and a closed position (FIG. 13). ~ linkage system 84 coupled by a drive rod 86 between thç drive piston 68 and the jaw set 78 serves to adva~ce the jaw set and close the jaws 80 and 82.
Fasteners 22 are supplied one at a time from a fastener assembly 20 contaLned in a magazine B8 mounted on. the front portion of the track member 74 by a bracket 90. Magazine 88 is of conventional construction and includes a spring loaded pusher 91 urging fasteners 22 upwardly with , .~.

20~Lr7~L2.~

the lead fastener 22 in position to be picked off and gripped by the jaw set 78 as it is driven from its standby position. As best seen in FIG. 10, the undersides of jaws 80 and 82 are offset and inclined to register with the angularly offset orientation of fasteners 22 in the assembly 20. The jaws 5 grip a fastener 22 in the region of the corners s4, and the jaws are at dif~er-ent elevations relative to the track member 74 to properly engage the fas-tener. This inclined or offset fastener position is maintained throughout the drive stroke.
Jaws 80 and 82 are formed at the front ends of a pair of jaw levers lo 92 and 94 pivoted intermediate their ends by a pin projecting below a Te-ciprocal shuttle block 96. E3lock 96 includes a downwardly projectin~
runner 98 that slides in a track (not shown) in track member 74 between a forward stop position defined by a surface 100 and a rear stop provided by a screw 1()2 that captures the shuttle block upon the track member 74.
LiDLkage system 84 includes two links 104 and 10~ pivoted to the rear ends of the jaw levers 92 and 94. The rear ends of links 104 and 106 are pivoted in common to a drive fitting 10~ attached to the front end of drive rod 86.
In accordance with a feature of the present invention, during a drive 20 stroke the fastener 22 is dei~ormed in two distinct and discrete deformation stages. The first stage Occuls in the first pa~t of the drive stroke as the fas-tener is predeformed as seen in FIG. 12 and FIG. 5 so that its legs are in-wardly inclined but separated by a gap. This shape is optimum for appli-cation of the fastener to a workpiece, and is maintained without further -25 defo~nation as the ~astener is advanced through the rest of the drive stroke to the fastener application region. I
A pair of cam members 110 and 112 are defined on the track mem-ber 74, one to each side of the path of the runner 98. Dur~n~ the initial part of a drive stroke, these cam members are co~tacted by cam follower 30 surfaces 114 on links 104 and 106. Surfaces 104 and 106 lead to relief sur-- faces 116 provided on the undersides of the links 104 and 106 in order to limit the predeformation of the fastener 22 to a brief and discrete part of the drive stroke.
Tool 60 includes a nose portion 118 with a pair of guide fingers 120 35 e~tendin8 into the fastener application region 76. The fingers 120 are use-, .~ .
. .

. .

2~ 7~2~

ful for gathering or positioning or holding a workpiece or fo~ positioning the tool 60 relative to a workpiece.
In operation, the tool 60 is initially in a standby or rest position with the drive piston 68 retracted as seen in FIG. 9. An assembly 20 of fas-teners 22 is loaded into the magazine 88 and the endmost fastener 22 is urged by pusher 91 into a drive position (FIG. 10) in registration with the jaws 80 and 82. A supply of pressurized air is lntroduced to the housing 62 through the ~ttin8 72.
To begin a fastener applying operation, trig8er 70 is operated to move the piston 6~, drive rod 86 and drive fitt~ng 108 in the forward direc-~ tion in a drive stroke. The linkage system 84 pushes the jaw set 78 for-`` w~d and the jaw set 78 pushes the shuttle block 96 forward. At the be-ginning of the dri~e stroke, the jaws 80 and 82 pick a single fastener 22 ofi~
of the assembly 20 carried by the magazine 88. The tendency of the di-verging li~s 104 and 106 is to move the jaws 80 and 82 to their closed po-sition. However, the closing force is overcome by the mechanical resis-tance of the fastener 22 to deformation and the closing force serves to grip the fastener 22 securely without deforming it.
Ea~ly in the first part of the drive stroke, the cam follower surfaces 114 on links 104 and 106 engage the cam abutments 110 and 112. As a re-sult the links 104 and 106 are forced apa~t from the position seen in FIG.
11 to the position seeD in FIG. 12. Consequently, the jaws 80 and 82 are forced together to a pa~tially closed position. This partial closing causes a first stage of fastene~ defolmation as the fastene~ z2 is pIedeformed and its legs are i~wardly inclined to the preferIed fasteneI applying position. ~
l~he f~rst stage of deformation ends when the cam follower surfaces 114 pas~ the abutments 110 and 112 and the abutments 110 and 112 enter relief regions resulting from the provision of relief surfaces 116. When t~is occurs, no further outward force is applied by the abutments 110 and 112 to the links 104 and 106 and both closing of the jaws 80 and 82 and deformation of the fastener 22 is discontmued. As the drive stroke contin-ues, the gap b~tween the fastener legs is maintaiDed as the jaw set 78 is advanced into the fastener application region 78.
As the jaw set 78 and shuttle block 96 reach the end of the dri~e stroke, the runner 98 stops against the stop surface lO0 as seen tn FIG. 13.

:

~ .

7 ~ 2 ~

The drive piston 68, drive rod 86 and drive fitting 108 continue moving forwa~d. As a ~esult, the links 104 and 106 are pivoted further apart and the jaws are forced to their closed position. The fastener 22 is formed into a loop or ring around the workpiece in the re~ion between the guide fin-5 gers 120. FollowinO the dTive st~oke, pressule is relieved at the rear of thedrive piston 68 and the tool is returned to its standby position ready to ap-ply another fastener.
While the invention has been described with refeTence to the em-bodiment shown in the dlawings, the details a~e not intended to limi-t the 10 scope of the invention as defined in the following claims.

' ~:, ' .
-.

,~
.~ r .

.''~; ~ :
. . , ~ . . :
: . .:

Claims (8)

1. A hog ring fastener of the type that is to be deformed into a loop in order to encircle a workpiece, said hog ring fastener comprising a unitary body including a base and two legs arranged generally in a U-shape, said base and legs being arranged along straight lines joined at right angle corners, each leg being perpendicular to said base, and said legs being arranged at an offset angle with respect to one another, said offset angle being large enough to permit the ends of said legs to move past one another during deformation into a loop, and said offset angle being small enough to position said legs adjacent to one another at a region of intersection after deformation into a loop.

2. A hog ring fastener as claimed in claim 1, said offset angle being between two and ten degrees.

3. The hog ring fastener of claim 2, said offset angle being about five degrees.

4. A hog ring fastener as claimed in claim 1, said legs having points defined by bevelled surfaces lying in planes nonparallel to the base.

5. The hog ring fastener of claim 4, said legs having ends with "C" points.

6. The hog ring fastener of claim 1, said right angle corners comprising rounded transition segments joining said legs to the opposed ends of said base.

7. The hog ring fastener of claim 1, said unitary body being made of wire with a uniform cross section throughout and said legs being of equal length.

8. An assembly of hog ring fasteners each as defined in claim 1, said fasteners being adhered together in side by side position, said bases all lying in a first plane, and said legs all lying in second and third planes that are parallel to one another and perpendicular to said first plane.