Note: Descriptions are shown in the official language in which they were submitted.
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litle Automatic Tie Gun
Field of the Invention
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This invention relates to the automatic application
of ties.
Background to the Invention
It is often necessary to tie an elongate roll or
bundle, more especially bundles of elongate objects such
as bundles of cablesor wires which if left unbound might
present a hazard as well as being unsightly. One way in
which cables are often bound together is by flexible
plastic ties which have an integral fastener, or buckle,
at one end through which the tail end cf the tie is
threaded once it has been passed around the bundle of
cables. Manual application of the ties is slow and
laborious, and it is therefore desirable to have a tool
which automatically performs the binding operation.
Prior Art
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A gun for automatically applying ties has been
designed in which a pair of jaws can be closed around a
bundle of cables, and a flexible tie pushed forwards by
a plunger so that the tail is pushed around the loop
defined by the jaws and through an apertured buckle at
the other end of the tie. The tail is then pulled tight,
twisted by 90 with respect to the buckle to lock it in
place, and the excess length cut off. Ties are supplied
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singly to this gun from a pre-loaded magazine which is
mounted on the exterior of the gun. Some of the
disadvantages of such a gun stem from the type of tie
which is used; the "twist and lock" type of tie has to be
overtensioned then relaxed back before it locks, which
does not always provide satisfactory tensioning7 also the
fastened tie has a knobby finish at the buckle, which is
apertured so that the tail of the tie is threaded at
approximately right angles to the longitudinal direction
of the tie adjacent the fastener. Furthermore the gun is
made in a sealed unit which is heavy, bulky and cannot be
readily serviced.
Another gun has been proposed in which ties are
conveyed one at a time from a magazine mounted remote from
the gun, but is otherwise similar to that previously
described. ~ third machine uses separate buckles and a
continuous spool of tape. Neither of these machines have
proved consistently reliable in use.
Obiect of the Invention
The present invention is directed towards a tie sun
which may provide a reliable tie feed mechanism, which may
be readily serviced, and which may incorporate standard
replaceable components.
The Invention
In accordance with one aspect of the invention there
is provided a to~l for automatically applying, around an
elongate roll or bundle, a flexible tie having a flat tail
and an apertured head at one end of the tail, the tool
feeding from a supply of said ties in the form of a belt
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in which the ties are disposed side-by-side with each
other and are interconnected by integral bridging pieces,
said tool comprising a push rod, driving means for causing
said push rod to perform an operating cycle consisting of
a forward stroke and a rearward stroke, indexing means
driven by the push rod during the rearward stroke of an
operating cycle, said indexing means advancing the belt
such that the leading tie of the belt is stepped laterally
into a tail forward, ready position within the tool and in
front of the tie rod with the apertured head of said tie
angled relative to the remainder of the tail so that its
aperture is oriented ready to receive the tail, means for
cutting said leading tie from said belt, guide means at
the forward end of the tool whereby, during the forward
stroke of the next operating cycle of the push rod, said
push rod drives the tie forwardly to advance the tail in a
loop around the guide means to cause the free end of the
tail to enter the head aperture to interlock therein,
means or gripping and pulling the free end of the tail
(once passed through said apertured head) to tension the
tie around the roll or bundle~ a knife for cutting the
tail behind the head, and a tension-sensing means for
actuating said knife when a predetermined tension in the
tie is reached.
In accordance with another aspect of the invention
there is provided a tool for automatically applying around
an elongate roll or bundle, a flexible tie having a flat
tail and an apertured head at one end of said tail, the
tool feeding from a supply of said ties in the form of a
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belt in which the ties are disposed side-by~side w~th each
other and are interconnec~ed by integral bridging pieces,
said tool having indexing means for advancing the belt
such that the leading tie of the belt is stepped laterally
into a tail-forward, ready position within the tool, means
for cutting said leading tie from said belt, me~ns for
driving tail-first from the tool the tie which is in the
tail forward, ready position, means at the forward end of
the tool for guiding the tie tail around the roll or
bundle to be tied as the tie is driven from the tool and
such that the free end of the tail passes through the
apertured head to interlock therein, means for gripping
and pulling the free end of the tail ~once passed through
said apertured head) to tension the tie around said roll
or bundle, a knife for cutting the tai.l behind the head,
and tension-sensing means for actuating said knife when a
predetermined tension in the tie is reached.
The indexing means conveniently includes a rotary drum
the rotation of which is indexed to the stroke of a push
rod so that the drum sequentially engages a plurality of
laterally connected flexible ties and conveys each tie in
turn to a position in front of the push rod which pushes
the tie, which has been disconnected from its adjacent
ties, so that one end of the tie passes along a guide and
into engagement with the apertured head which is joined to
the other end of the tie.
Once the one end of the tie is engaged with the head
- it may be pulled until the loop formed by the tie
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grips the roll or bundle at a predetermlned tension.
The tool preferably includes a unit which senses the
tension to which the tie has been pulled, and at a
predetermined tension, which may be adjustable, cuts
off the excess length of the tie adjacent the head.
The head of the flexible tie may have a
longitudinal aperture through which the tail of the tie
is threaded, and a resiliently biased pawl which engages ~;
- with ratchet serrations in the tie and prevents the tie
unthreading but permits the tail to be pulled further
through the aperture. With this type of tie, once
threaded, the threaded portion of the tie overlies the
portion of the tie adjacent the head. The ties may be
injection moulded as a belt with bridging pieces
connecting the tails of the ties.
The tool may be controlled by a fluid operated
cylinder and piston unit, with the drum rotation, the
rod pushing and tie cutting indexed to the stroke of the
piston in the cylinder.
Brief Description of Drawings
A tool in accordance with the invention is now
described by way of example with reference to the
accompanying drawings in which:
Figure 1 is a section through an embodiment of the
invention in the form of a tie gun;
Figure 2 is a plan view from above of the tie gun
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of Figure 1;
Figure 3 is a view in the direction of arrows A-A
of the gun of Figure 1;
Figure 4 is a view of the ratchet mechanism which
rotates the drum of Figure 1;
Figure 5 shows the preferred type of flexible tie;
Figures 6a and 6b show two alternative embodiments
of support for a belt of flexible ties;
Figure 7 is a front perspective view of the tie
gun of Figure 1;
Figures 8a and 8b are perspective and cross-
sectional views of a preferred form of drum used in the
invention;
Figure 9 shows a preferred mechanism for dis-
connecting the ties from the adjacent ties;
Figure 10 illustrates a volute by which in thepreferred embodiment the ties are positioned;
Figures 11a, 11b and llc show a lipped slot,
along which, in the preferred embodiment, the tie is
diverted;
Figure 12 shows a section through a threaded
tie;
Figure 13 is a perspective view of the buckle
of a tie;
Figure 14 illustrates a bundle of cables bound
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by flexible ties;
Figure 15 illustrates a belt of flexible ties,
Figure 15b showing a preferred form of belt for use in
conjunction with the tie gun of Figure 1;
Figures 16a and 16b are sectional views through
a flexible tie;
Figure 17 illustrates an elongated belt of ties
comprising several shorter belts joined together; and
Figures 18a to 18e show a modified form of low
profile flexible tie.
Description of Embodiments
The tie gun illustrated in Figure 1 is particularly
adapted for binding cables together with flexible ties,
the fastenings of which have a low profile when secured
around the cable bundle. Operation of the gun is
controlled by a pneumatic cylinder and the various stages
in the operating cycle are indexed to the stroke of the
piston of the cylinder. In the following description,
before the detailed construction of the gun is described,
the general sequence of its operation is outlined along
with a brief description of the tie and the feed
mechanism. Then the operating sequence is explained in
more detail with reference to the drawings, and this is
followed by a detailed description of the construction l
25 of the various units of the gun which perform specific ,
functions which are referred to in the operating sequence,
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and also by a more detailed description of the flexible
ties used in the gun.
sriefly, the operating sequence of the gun is
governed by the piston of the pneumatic control cylinder
which is linked to a ram so that during the inward and
outward strokes of the piston, which respectively produce
forward and rearward strokes of the ram, flanges on the
ram engage with and activate other parts of the mechanism.
The piston is activated to move inwardly by depression
of a trigger, whereupon a guide loop is closed about the
bundle of cables which are to be bound and the tip of a
flexible tie is pushed forward so that it passes around
the cable vla the guide loop and is threaded through a
fastener in the form of an apertured head on the other
end of the tie. Once the tie is threaded the piston
commences its outward stroke and the tip of the tie is
gripped, the tie pulled tight, and, once a predetermined
tension is reached, the excess length of tie is trimmed
off. Then, whilst the piston completes its ouLward
stroke, another tie is advanced to the firing or ready
position, the scrap trim is ejected and the guide loop
is released from the bound cable. This completes an
operating cycle of the ram initiated by a single
depression of the trigger.
The feed mechanism by which the ties are advanced
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includes a cylindrical drum with longitudinal recesses
which accommodate the tails of the ties as they are fed
laterally into the gun from one side of the drum. The
ties are advanced by rotation of the drum during the
latter part of each outward stroke of the piston which
brings successive ties to the topmost position ready for
subsequent firing. In order to simplify the indexing
of the ties into their respective recesses, in the
correct orientation, the ties are joined together by
bridging pieces to form a belt. Once a tie is in the
firing position it is cut free from its bridging pieces
by a cropping mechanism.
In order to achieve a low profile fastening, a tie
may be employed in which the tail threads through a long-
itudinal aperture in the buckle so that the threadedportion lies along the portion of the tie adjacent to
the buckle rather than projecting perpendicular to it.
To thread this type of tie the buckle needs to be
rotated through 180 (compared with when the tie is laid
flat) to receive the tail which has been passed around
the bundle of cables. Therefore, in addition to advancing
successive ties to the firing position, the feed mechanism
of the gun also rotates the buckle to the correct
orientation for receiving the tail. This is achieved by
the buckles of the ties, which overhang the rearward
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edge of the drum, abutting a volute which causes the
buckle portion of the tie to be progressively bent
outward and then back on itself as the drum is rotated,
so that the 180 rotation has been completed by the time
the tie is in the firing position.
Referring now to Figure 1, the tie gun is shown
generally as 1, and has a spring return trigger 2. A
guide loop 3 is provided at the end of barrel 4 of the
gun, and can be closed about a suitable bundle of cables
adjacent to which the end of the barrel 4 has been
placed. Trigger 2 is provided with an inclined surface
5 which abuts an inclined surface on the spool 6 of a
valve 7 so that upon a depression of the trigger the
spool 6 is lifted and air is provided to one end of a
pneumatic cylinder 8 which, as may be seen from Figures
2 and 3, is disposed in the barrel 4 of the gun with its
piston rod free to extend into rear portion 9 of the gun
1. Spool 6 is held in its lifted position by detent 10
and the extended piston of the pneumatic cylinder retracts
moving a ram 11, which is connected to the piston, to the
left as viewed. Ram 11 is provided with a flange 12 at
its end remote from the barrel which abuts a flange 13
on a biased rod 14, so that as flange 13 moves leftwards
it permits rod 14 to move left under the influence of
spring 15, which closes guide loop 3. The barrel end of
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ram 11 acts as a pusher for a tie 16, whereby said ram
may more generally be referred to as a push rod. As
it advances it pushes the buc~le 17 of a tie 16 into a
pair of spring loaded jaws 18, which are mounted on the
forward end of the barrel of the tool, the tail end of
the tie being pushed down a lipped slot 19, around the
guide loop 3 and through the buckle. Ram 11 is now in l`~
its most leftward position, and the piston is fully
retracted. In this position an inclined surface 20 on
flange 12 has engaged with a corresponding upper inclined
surface 21 on spool 6 and pushed down the spool, which is
then retained in its down position by detent 10, which
causes the action of the pneumatic cylinder 8 to be
reversed.
On the outward stroke of the piston the tail of
tie 16, which is gripped by a clamp 22, is pulled, the
buckel being retained by jaws 18 until a predetermined
tension is sensed by a cut-off unit 23, whereupon a rod `
24 is moved to the right causing knife 25 to sever the
20 tail of the tie 16 close to the buckle 17. The release 1
of tension caused by cutting the tail resets the cut-off
unit which retracts the knife 25, and also causes the
piston to continue to extend at an increased speed. A
scrap release trigger 26 which is spring loaded upwards ~-
but depressed during the passage of the ram rod 11 over
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it, is then released as it is cleared by the end of ram 11,
and this trigger then engages clamp 22 so that the tail
is released, the tail being impelled into scrap bottle 27
partly under its own momentum and partly by pneumatic
ejection. A projection 28 on ram rod 11 engages a bell
crank 29 to advance a feed ratchet 30 which rotates drum 31
and aligns a new tie with the end of the ram 11 ready for
the next cycle. Figure 4 shows the feed ratchet 30 and
bell crank 29 in detail. Bell crank 29 is sprung so that
it can move to the next ratchet position, when it is
released on the inward stroke of the piston, ready to
rotate the drum 31 during the subsequent outward stroke. I
Precise positioning of the drum may be achievecl by a l;
rotation detent in which a sprung member indexes with
15 notches in the drum once it has been rotated by the bell ,
crank and ratchet. Whilst the out:ward stroke of the
piston continues further, a flange on the ram rod 11
engages with a forked lever 32, the other end of which
engages a flange 33 on cut-off rod 24 to ensure that the
cut-off unit is properly reset, and finally, flange 12 of
ram rod 11 pushes flange 13 to the right which opens the i
guide loop 3 and releases the bound cable.
Figure 5 shows the construction of a suitable low
profile buckle with the threaded portion of the tail
lying parallel to the end of the tie adjoining the
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buckle. The ties, which may be made of injection
moulded plastics, are fully described hereinafter with
reference to Figures 12 to 18. Figures 6a and 6b show
two alternative forms of support for a belt of ties, in
the simplest case one or more pairs of curved supports
34 are used, or, if it is undesirable to have the belt
left waving, a magazine 35 in which the belt can be
coiled is used. The belt of ties is fed into the gun 1
via a slot 36 which can be seen in the front perspective
view of the gun in Figure 7. Having passed through the
slot the belt passes around drum 31 which is recessed
as shown in Figure 8 with lonqitudinal grooves 37 for
the ties and circumferential grooves 38 for the
bridqing pieces between the ties. Longitudinal grooves
37 are deeper than circumferential grooves 38 so that
the ties are supported on the drum 31, by the bridging
pieces, above the base of the longitudinal grooves 37.
The longitudinal grooves may also serve, at one end, as
the notches into which the sprung member of the
rotation de-tent indexes. When a tie has passed around
the drum 31 and is aligned with the ram rod 11, it is
cut free from its bridging pieces by reciprocating
action of crops 39, which are actuated via lever linkage
40 and projection 28 on ram 11 during the outward stroke j~
of the piston in the cycle of operation of tying the
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immediately preceding tie. Figure 9 sc~ematically shows
the action of crops 39; the action is synchronised to
take place immediately after the tie has been rotated
into position by feed ratchet 30 both the feed ratchet
30 and the crops 39 being activated by projection 28.
The scrap bridging pieces drop into a waste chute 41 and
are exhausted into waste bottle 27.
Whilst drum 31 is progressively rotated the
buckle end of the ties are gradually bent over by a
voluted surface as shown in Figure 10, so that the
buckle is eventually bent through 180 with respect to
the tail. Depression of trigger 2 causes the tie to be
advanced in this bent over condition by the advancing
ram 11 the buckle engaging with buckle clasp 18, and
the tip being directed down the S-bend of lipped slot
19, around the cable and through the buckle. The lips
of slot 19 shown in Figure 11a retain the tie within
the slot during its passage down the S-bend (Figure 11b)
but once the tensioning operation commences the tie can
be pulled free as shown in Figure 11c.
Drum 31 is provided with cutaway apertures 43
in the circumferential groove 38, each of these being
arranged so as to be covered by the bridging pieces of
the belt of ties (see Figure 8) when there is a tie in
the respective preceding longitudinal slot 37. ~n
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airline has an open end located such that after the last -
tie of a belt of ties feeding into the gun has been engaged,
and the drum is rotated to the next position where it
would otherwise have engaged the next tie, air from airline
passes through the uncovered aperture 43 and causes a
whistle indicating that a new belt of ties is required.
The cut-off unit 23 is shown in Figure 1; for
clarity it is illustrated displaced rearward from its
correct position whilst Figure 2 shows the cut-off unit
correctly positioned. As a tie is tightened around a
bundle of cables, pressure in the pneumatic cylinder 8
rises in proportion to the tension in the tie. The cut-
off uni,t is therefore responsive to the pressure in the
pneumatic cylinder and can be adjusted such that the
tightened tie is cut-off at a predetermined tie tension.
A line 45 connects the cut-off unit to the pneumatic
cylinder, so that the pressure applied to the left (as
viewed) of a poppet 46 is equal to that driving the
piston of the-pneumatic cylinder 8. The poppet 46 is -~
held in position by a spring ~7, until the applied air
pressure exceeds the pressure exerted by the spring 47,
whereupon the poppet is unseated and moves to the right
moving cut-off rod 24 and actuating knife 25. Release
of the tie tension once the tail has been cut r and the
drop in air pressure in the cut-off unit due to sudden
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expansion of air when the poppet is unseated, enables
the poppet 46 to be pushed left again by spring 47,
Meanwhile the piston of pneumatic cylinder 8, also
relieved of the tension of the tie, completes its stroke
5 and lever 32 engages flange 33 and ensures that the -
poppet 46 is reseated in its original position. Different
tie tensions may be obtained by adjustinq knob 48 which
changes the compression in spring 47.
Referring to Figures 5, 12 and 13, the buckle
17 has a longitudinal aperture 49 through which the tail
can be threaded so that ratchet serrations 50 on one
surface of the tail engage with a pawl 51, which prevents
the tail from being pulled back out of the aperture 49
but enables it to be advanced through to tighten the loop
52 formed by the tail. A slot 53 is provided beneath
pawl 51 which enables it to be res:iliently depressed by
the serrations 50 for ease of advancement of the tail
through the aperture 49.
Figure 14 shows a bundle of cables bound by
flexible ties illustrating the low profile fastening
achieved by the flexible ties used in the tie gun. A
low profile tie of this type may, as well as being
visually appealing, be particularly advantageous for
example when the bound cables are to be inserted through
restricted apertures, or into confined spaces, such as
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may occur when fitting wired looms. In the drawings thetie is illustrated with serrations on the tail of the
tie such that when the tie is threaded the serrations
are on the inside of the loop. Although this configura-
tion is often preferred because the serrations can alsoact to grip the cables or other items about which the
tie is wound, the serrations may alternatively be formed
so that they are on the outside of the loop, and in this
case the pawl is formed extending down from the upper
surface (as viewed) of the buckle 17.
The ties may be connected by integrally
moulded bridging pieces as shown in Figure 15a. However
in order that the fasteners may be bent outwards by the
voluted surface 42 without requiri.ng previous separation,
the ties are preferably fabricatecl, as shown in Figure
15b, with the heads separate and t:he two bridging pieces
54 between the tails of adjacent ties. To ease the
tooling requirements the belt of ties may be moulded with
the tail bent through 90 near the buckle 17, as is shown
in section in Figure 16. These bent belts can be pressed
flat for packing, and when used the preformed bend
facilitates turning the buckle into the position shown
in Figure 16b for threading by the end of tail. In
order to achieve a longer belt than can be conveniently
moulded, individually moulded belts may be connected lnto
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a continuous longer belt as shown in Figure 17. To
minimize jamming of the gun when used with such a
continuous belt, joints 55 between the individually
moulded belts should be made as smooth as possible.
Figures 18a to 18e show a modified form of low
profile tie. This tie is illustrated with serrations
which will be disposed on the outside of the loop when
the tie is threaded. The serrations engage with
similarly profile teeth 56 extending from the upper
10 surface of the buckle. Channels 57 are provided in the ¦;
buckle which accommodate ridges 58 along the edges of
the tail.
The gun mechanism may be housed in a die-cast
body, one half acting as a chassis onto which the
component parts of the mechanism may be mounted, and the
other half acting as a cover. A suitable type of
pneumatic cylinder is a Martonair Midget M/6010 which
has a lOmm bore, 4mm diameter rod and 130 mm stroke; a
suitable type of valve is a Martonair M/1555/1.
Various modifications to the gun may be made,
for example the feed mechanism may be modified so that
the cylindrical drum or other indexing means can
alternatively, or additionally, engage non-connected
ties, which may be of use when the gun is not intended
for intensive use. Furthermore, the gun can be adapted
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for use with other types of flexible ties having
apertured heads or buckles.
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