Variable pitch feed of fasteners

Variable pitch feed of fasteners by a unitary, single toothed feed member. Back-up of the fasteners from the feed position is prevented and the individual fasteners are securely positioned for ejection.

BACKGROUND OF THE INVENTION 
This invention relates to the feed of fasteners, and more particularly to 
the variable pitch feed of fasteners. 
A common fastener for tagging or attaching items is of the kind shown and 
described, for example, in U.S. Pat. No. 3,380,122. The fasteners are in 
an assemblage including a connecting bar, a plurality of coplanar 
connecting stubs extending from the connecting bar, a cross bar angularly 
disposed on each stub, a filament extending from each cross bar, and, 
typically, a head attached to each filament. Common fastener attaching 
apparatus, such as is shown and described for example in U.S. Pat. No. 
4,416,407 are designed to install fasteners disposed at a unique distance, 
relative to each other, on the connecting bar. Typically, a feed wheel is 
provided having circumferential teeth matable with the assemblage stubs, 
operable to advance the assemblage in the apparatus. The number and pitch 
of the feed wheel teeth correspond to the pitch, or relative separation, 
of fasteners on the assemblage. However, fasteners are provided in 
varieties, for which it is common practice to have a different fastener 
dispensing apparatus for each variation. 
Accordingly various attempts have been made to provide for feeding, in a 
single apparatus, of different assemblages, each having a unique pitch. 
Japanese publication No. 48939 dated 5/2/81 shows a fastener installation 
apparatus including a feed member having cooperative feeding and 
anti-back-up members. In one embodiment, an advance mechanism includes a 
U-shaped rod, the rod ends engagable with an installed fastener 
assemblage. In an alternative embodiment, two rods engage the assemblage. 
In each embodiment, an upper rod acts to advance the assemblage, and a 
lower rod serves to prevent upward movement of the assemblage during 
feeding. Both rods may bend in either direction, however, each rod end is 
provided with an angled upper surface so that downwards movement of the 
assemblage is favored. The feeding strength of this apparatus is limited 
by the resiliency, or biasing strength, of the upper rod. As the strength 
of the upper rod is increased, so too must the strength of the lower rod 
be increased, otherwise, the assemblage will back-up as the upper rod is 
urged upwardly. As a result, advancing strength is dissipated by the lower 
rod. Thus only a small advancing force can be generated by this design. 
Therefore, this apparatus is vulnerable to misfeeding and jamming, 
particularly where the assemblage fails to slide smoothly within the guide 
grooves of the apparatus. 
U.S. Pat. No. 4,461,417 shows an apparatus designed to install fastener 
assemblages of varying pitch. A claw is pivotally mounted to a vertically 
moveable cam plate, the claw being biased in the direction of the 
connecting bar. A stationary claw with downwardly angled teeth is provided 
for the purpose of preventing upward movement of the connecting bar during 
feeding. In operation, the cam plate is raised, causing the claw to be 
dragged upwardly along the connecting bar. When the trigger is released, 
the cam plate is lowered, wherein the claw, or in an alternative 
embodiment, the teeth, engage the connecting bar and urge the assemblage 
downwardly. Since the claw is not drawn away from the connecting bar, an 
upwards force is exerted upon the connecting bar. A disadvantage to this 
design resides in the pivotal arrangement of the claw. As the cam plate is 
raised, the claw is pressed with continually greater force against the 
connecting bar, raising the potential for a jam. As the cam plate is 
lowered, the claw does not contact the connecting bar until the claw has 
pivoted into position, thus the connecting bar may not be advanced 
sufficiently to position the next fastener for ejection. Additionally, the 
design depends on the claw or teeth cutting into the connecting bar. Since 
fastener assemblages are fabricated from a wide variety of materials, 
there exists the possibility that the claw will either imbed itself too 
deeply into the connecting bar, causing a jam, or will fail to engage, 
resulting in a misfeed. 
In a third approach, taken in U.S. Pat. No. 4,465,218, a tooth is moveably 
mounted within a pivotable base. The tooth is biased in the direction of 
the assemblage, pivoting on a pin. To prevent the tooth from 
overextending, a pin extends from the base into an aperture located near 
the tooth. When the trigger is depressed, the base pivots urging the tooth 
upwards. The tooth is caused to pivot, deflecting around the next stem. 
When the trigger is released the tooth engages the stem and urges the 
assemblage downwards. One disadvantage of this design is that all of the 
advancing and biasing force is exerted upon a small pivot pin which is 
subject to wear and breakage. Another disadvantage is that the design 
requires two carefully mated parts which must be assembled, thus raising 
the cost of the apparatus. 
To prevent back-up of the assemblage during feed, the '218 patent provides 
a tooth biased in the direction of the assemblage. The tooth has an upper 
profile disposed at an angle to the axis of the assemblage, thus 
permitting downwards movement. A lower profile is disposed perpendicular 
to the axis of the assemblage, thus preventing upward movement of same. A 
problem with this design is that the device provides for only a fixed stub 
thickness. A thicker stub would not fit beneath the lower profile. A 
thinner stub could move up or down below the lower profile. As a result, 
the push rod, or plunger, may not squarely engage the cross bar, and thus 
jamming can arise. Additionally, this design does not permit the fastener 
assemblage to be withdrawn without additional devices for retracting the 
anti-back-up member. 
It is therefore an object of the invention to provide a reliable variable 
pitch fastener installation apparatus. 
It is a further object of the invention to provide for high strength 
advancing of the fastener assemblage. 
It is an additional object of the invention to provide for secure 
positioning of the fastener to be ejected, while simultaneously preventing 
unwanted back-up of the assemblage during feeding. 
It is another object of the invention to provide for simple and easy 
removal of a fastener assemblage. 
It is yet another object of the invention to provide a fastener 
installation apparatus of relatively very low cost, incorporating a small 
number of parts, which functions with great reliability. 
It is an additional object of the invention to provide for reliable 
assemblage feeding and positioning, despite significant variations in 
materials and dimensions in the fasteners installed. 
SUMMARY OF THE INVENTION 
In accomplishing the foregoing and related objects, the invention provides 
a variable pitch fastener dispensing apparatus having a unitary feed 
member. A location member is provided cooperative with the feed member to 
securely position the fasteners for ejection. 
In accordance with one aspect of the invention, the elements of the 
invention cooperate with existing fastener installation apparatus 
mechanisms of the type including a trigger, and an ejection plunger 
cooperative with the trigger via a slide, such as is shown and described 
for example in U.S. Pat. No. 4,416,407. A second slide having posts at 
either end of the lever serves to actuate the feed mechanism of the 
invention. A fastener assemblage installable with the invention includes: 
a connecting bar; a plurality of coplanar, spaced apart stubs; a cross bar 
disposed about the end of each stub; a filament extending from each cross 
bar; and a head portion disposed about the end of each filament. 
In accordance with another aspect of the invention, a feed member is 
provided, coupled to a slide via a linking rod, pivotally mounted to the 
apparatus frame. A resilient finger extends in a curved manner from the 
feed member, supported over part of the curve by a mating ridge on the 
apparatus frame. A tooth is disposed about the end of the finger, 
positionable between stubs of an installed fastener assemblage. The tooth 
has an angled upper surface, and a lower surface defining a plane 
substantially parallel to the axis of the installed connected bar. As the 
trigger is depressed, the feed member pivots, whereby the finger bends to 
permit the tooth to ride over the stem of the next fastener to be 
advanced. When the trigger is released, the tooth engages the upper 
surface of the stem and urges the assemblage downwards, positioning the 
fastener for ejection. 
In accordance with an alternative embodiment of the invention, a feed 
member is rotatably mounted to the apparatus frame via an elongated recess 
cooperative with a pin. A tooth is disposed about the upper portion of the 
feed member, engageable with the assemblage. Friction is applied to the 
feed member, at a location between the rotating pin and the linking rod. 
As the trigger is depressed, the feed member moves about the friction 
area, disposing the pin at the forward side of the elongated recess. As a 
result, the tooth is drawn away from the assemblage. As the trigger is 
released, the feed member moves about the friction area, disposing the pin 
at the rearward side of the recess, positioning the tooth above the 
fastener next to be ejected. As the trigger is further released, the feed 
member pivots about the pin, whereby the tooth urges the fastener into 
position for ejection. 
In another embodiment of the invention, a location member is provided for 
positively orienting the fastener for ejection, and for preventing upwards 
movement of the assemblage during the advancing steps. The location member 
is biased in the direction of the fastener assemblage, and has a tooth 
cooperative with the fastener studs to securely position successive 
fasteners. The tooth has an upper profile defining a low angle with 
respect to the axis of assemblage movement, while a lower profile defines 
a higher angle. A result, the assemblage encounters a low resistance 
towards downwards movement, as when advancing, and a high resistance to 
upwards movement, as when the feed member tooth moves upwards. 
Additionally, the angled lower surface applies a constant force against 
the fastener, maintaining same in proper orientation for ejection.

DETAILED DESCRIPTION OF THE INVENTION 
With reference to FIGS. 1-9, the present invention provides a fastener 
dispensing apparatus, or gun 10, having a variable pitch feed member 200, 
and a location member 300. Elements 200 and 300 cooperate to provide for 
reliable advance of a variety of fastener assemblages. 
As can be seen in FIG. 1, the fastener apparatus 10 of the invention 
receives a fastener assemblage 100 in a guide groove 12 disposed at the 
front of the apparatus. Assemblage 100 comprises a connecting bar 102; a 
plurality of coplanar stubs 104; a cross bar 106 perpendicularly disposed 
about the end of each stub 104; a filament 108 extending from each cross 
bar 106; and, typically, a head portion 110 disposed about the end of each 
filament. The distance between stubs 104 represents the "pitch" of the 
assemblage. It has become increasingly common for fasteners to be disposed 
at a closer pitch on the connecting bar, thereby reducing mold size and 
lowering cost, as well as providing for less frequent reloading. However, 
prior fastener assemblages exist in great quantity. Therefore, there 
exists a variety of different pitch fastener assemblages, typically 
ranging from 0.04" to 0.15" (1-4 mm) between adjacent stubs. The present 
invention provides for installation of a wide range of these fastener 
assemblages. 
The feed and location members of the invention may be employed with a 
variety of known actuating mechanisms. What is required is a frame for 
supporting the elements, a plunger for ejecting the fasteners, and means 
for pivoting the feed member. U.S. Pat. No. 4,416,407 provides such an 
apparatus, which includes a frame 14, a trigger 13, a plunger 15, a 
control lever 16 and a linking rod 19h. While the '407 mechanism is 
illustrated, it should be understood that a variety of mechanisms can be 
employed in combination with the elements of the invention, as will be 
understood from the description below. For the purpose of this discussion, 
with reference to FIG. 1, front is indicated by arrow F; rear, or backward 
by arrow R; up by arrow U; and down by arrow D. 
With reference to FIGS. 2 and 4, a preferred embodiment of the invention 
includes a feed member 200, comprising a pivot pin 202, link aperture 204, 
and finger 206 having tooth 208. Feed member 200 is preferably fabricated 
from a resilient wear resistant material, such as NYLON or AN ACETAL 
RESIN. Pin 202 is received within the frame, or alternatively, the frame 
is provided with a pin matable with an aperture in feed member 200, so 
that the feed member has a fixed pivot. Aperture 204 couples to linking 
rod 19h. Finger 206 has a curved profile, and is integrally formed from 
the feed member body 210. The apparatus frame is provided with a curved 
ridge 20, matable with the curved profile of finger 206. Tooth 208 has an 
upper surface 212 defining an angle with respect to the axis of the 
installed assemblage, when the feed member is in an advanced position, as 
shown in FIG. 2. In a preferred embodiment, surface 212 thus defines an 
angle of 30.degree.-45.degree., preferably 40.degree.. In this position, 
the tooth lower surface 214 is approximately perpendicular to the axis of 
the assemblage. It should be understood, however, that a range of angles 
may be advantageously employed for surfaces 212 and 214, depending on the 
intended application. 
With reference to FIGS. 2 and 6, the operational steps in advancing the 
fastener assemblage 100 may now be described. As link 19h is advanced via 
slide 19s, feed member 200 is pivoted about the axis of pin 202. Link 19h 
provides a low resistance, low wear connection to feed member 100. As can 
be seen in FIG. 6(a), a tooth 208 is disposed above stub 112, which 
previously was coupled to a fastener, now ejected. After a fastener has 
been expelled through the needle, control lever 16 contacts post 19p-1, 
thus urging link 19h forwards. Feed member 200 rotates about pivot 202, 
whereby finger 206 is bent inwardly as tooth 208 is pushed back by stem 
114. Due to the angle of upper surface 212, tooth 208 slides easily over 
stub 114. As feed member 200 continues to rotate, tooth 208 moves in a 
direction tangential to the direction in which the assemblage is fed, 
shown by arrow A, FIG. 6B, thus causing tooth 208 to become free of stem 
114, whereupon finger 206 springs forward disposing tooth 208 between stem 
114 and the next succeeding stem 116. Control lever 16 next reverses 
direction as the trigger is released, and pushes back on post 19p-2. As a 
result, link 19h is drawn back, causing feed member 200 to rotate about 
pivot 202 in an opposite direction, shown by arrow B. Lower surface 214 of 
tooth 208 contacts the upper side of stem 114, and urges same into 
ejecting position as feed member 200 continues to pivot. FIGS. 6c, 6d. 
During this time, frame ridge 20 supports tooth 208, thus preventing 
upwards bending of finger 206. This cycle is repeated each time the 
trigger is depressed and released. Because the movement of tooth 208 is 
tangential to the axis of assemblage 100, clearance of tooth 208 is 
favored. As a result, a wider pitch range may be accommodated. 
Finger 206 is highly resistant to damage. Due to being integrally formed 
from the feed member body 210, bending force is distributed over an 
extended area, as opposed to a particular point. Moreover, great feeding 
strength is achieved by buttressing the finger with ridge 20. The 
resiliency of the finger may be varied, however, by employing a biasing 
spring 250 and pivot finger 252, such as is shown in FIG. 7. This 
alternative embodiment retains the advantage of being buttressable by 
ridge 20, yet permits a wide range of resilient forces, depending on the 
strength of spring 250. An alternative feed member 400 is shown in FIG. 8. 
Link 19h couples to aperture 402. A slot 404 cooperates with a pin 112 
mounted to the fastener apparatus frame. Alternatively, a pin may extend 
from feed member 400 into a recess in the frame. A tooth 406 is provided 
at the front of the feed member 400, having an angled upper surface 408 
and a substantially horizontal lower surface with respect to the 
longitudinal axis of slot 404. A frictional force is applied to the region 
indicated by dotted line 412. In operation, as trigger 13 is depressed, 
link 19h is moved forwards causing feed member 400 to pivot about friction 
region 412. As a result, pin 12 confronts side C of slot 404, whereupon 
tooth 406 is drawn away from the fastener stems. 
Reference line Z is provided to illustrate how feed member 400 is 
repositioned with respect to friction region 412 and pin 12. As can be 
seen in FIG. 8b, the upper toothed portion of feed member 400 moves in the 
direction indicated by arrow E, while the lower link apertured portion 
moves in the direction indicated by arrow F. As the trigger is released, 
link 19h draws the lower portion in the direction indicated by arrow H. 
Pin 12 is thus caused to confront side D of slot 404, whereupon feed 
member 400 is displaced with respect to friction region 412, in the 
direction of the fastener assemblage, causing the upper toothed portion to 
rotate in the direction indicated by arrow G. The next successive stem 118 
is engaged by tooth 406, whereby the fastener assemblage is urged 
downwards to position the next fastener for ejection, ultimately arriving 
at the positioning shown in FIG. 8a. 
Since tooth 406 is rigidly mounted to the feed member body 414, a great 
advancing force may be generated by this embodiment. 
To prevent the fastener assemblage 100 from moving upwards during cycling 
of feed member 200 or 400, an ejection location member 300 is provided, as 
shown in FIGS. 3, 5 and 9. Location member 300 comprises a base 302 having 
a slot 304, a stem 306 extending from base 302, biasing means 308, a stem 
guide 310, and a tooth 312. 
Location member 300 is positioned beneath feed member 200 or 400, wherein 
pivot pin 202 passes through slot 304. Stem guide 310 is formed as a 
groove in the fastener body, subject to and additionally providing support 
to plunger 15. Biasing means 308, for example a spring, is mounted on stem 
306, confined between guide 310 and body 302. Thus configured, location 
member 300 is urged in the direction of the installed fastener assemblage 
100. The length of slot 304 determines the maximum range over which 
location member 302 can move. Tooth 312 is provided with an upper surface 
314 defining an angle of low elevation, in a preferred embodiment, in the 
range of 25.degree.-35.degree., preferably 30.degree. with respect to the 
axis of location member 302 movement. Tooth 312 lower surface 316, is 
provided with a higher angle relative to upper surface 314, in a preferred 
embodiment in the range of 40.degree.-50.degree., preferably 45.degree. 
with respect to the axis of location member 302 movement. The importance 
of the angular surfaces can now be explained with reference to FIG. 9. 
In FIG. 9a, location member 300 is urging stem 120 downwards through a 
force exerted by lower surface 316. Stem 120 is prevented from moving 
beyond ejection location due to contact between cross bar 104 and the 
fastener apparatus frame. Due to the high angle of lower surface 316, a 
constant pressure is maintained against stem 118, rigidly locking same in 
ejecting position, thereby markedly reducing the possibility of jamming or 
misfiring. This aspect is of particular importance, since stem thickness 
can vary considerably among different fastener assemblages. Even where 
only one stem thickness is employed, molding variation and flash thickness 
can introduce variation. This problem is eliminated by location member 
300, which exerts a constant force downwardly on the stem, regardless of 
stem thickness. After the fastener connected to stem 120 has been ejected, 
feed member 200 advances assemblage 100, thereby causing stem 122 to be 
pushed downwardly against upper surface 314. Due to the low angle of upper 
surface 314, location member 300 is easily urged rearwardly, thus 
permitting the assemblage to be advanced. Concomitantly, as feed member 
200 is pivoted in direction A, lower surface 316 prevents upwards movement 
of assemblage 100, due to the high resistance imposed by the higher angle 
of surface 316. 
In feed embodiments 200 or 400, the fastener assemblage 300 is withdrawn by 
simply pulling the assemblage upwardly out of the guide groove. Feed 
member 200 or 400 can be pivoted backwards by depressing the trigger, 
whereby only the resistance of location member 300 is encountered. 
Alternatively, the trigger can be left undepressed, wherein feed member 
400 is urged rearwardly, as the assemblage is withdrawn. 
The present invention thus provides a fastener dispensing apparatus which 
can reliably advance fastener assemblage of differing pitch. A typical 
pitch range is between 0.045" and 0.080" (1.14-2.03 mm),(stem center to 
stem center), however, it should be understood that modifications, 
particularly to the tooth and or finger length, can be made to accommodate 
pitches outside this range. The invention enables reliable variable pitch 
feeding with a minimum number of parts. This is accomplished in one 
embodiment, in part, by reinforcing feed finger 206 with the apparatus 
frame, and in another embodiment, by the use of a frictional pivot. 
While various aspects of the invention have been set forth by the drawings 
and the specification, it is to be understood that the foregoing detailed 
description is for illustration only and that various changes in parts, as 
well as the substitution of equivalent constituents for those shown and 
described, may be made without departing from the spirit and scope of the 
invention as set forth in the appended claims.