Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02308885 2000-OS-19
IMPROVED TOOL HEAD FOR
AUTOMATIC CABLE TIE INSTALLATION SYSTEM
BACKGROUND OF THE IN'V'ENT)(ON
The present invention relates to a tool head and, more particularly, to a tool
head for use with an automatic cable tie installation system providing
improved
performance and reliability:
As is well-known to those skilled in the art, cable ties are used to bundle or
secure a group of articles such as electrical wires or cables. Cable ties of
conventional
construction include a cable tie head and an elongate tail extending
therefrom. The
tail is wrapped around a bundle of articles and thereafter inserted through a
passage in
the head. The head of the cable tie typically supports a locking element which
extends into the head passage and engages the body of the tail to secure the
tail to the
head.
Although cable ties are often installed manually, it is desirable in certain
applications to utilize an automatic cable tie installation system wherein
cable ties are
dispensed from a remote dispenser, and thereafter delivered to a tool head for
1 ~ application about a bundle of wires positioned within the jaws of the tool
head.
Automatic cable ties installation systems are well-known in the art, and are
disclosed
for example in U.S. Patent Nos. 4,790,225 and 4,498,506. It will be
appreciated that
the disclosed tool heads include a plurality of subassemblies each having
multiple
moving parts, the subassemblies cooperating together to deliver, tension and
cut the
- cable tie. To be commercially practical, the tool head must be capable of
repeatedly
applying a cable tie about the bundle of articles inserted within the jaw
assembly
CA 02308885 2000-OS-19
without jammiztg. The tool head must also be able to complete a cycle (wherein
one
cable tie is wrapped, tensioned and cut) within a sufficiently short interval
of time.
Those skilled in the art will appreciate that the foregoing requirements
demand
extremely accurate and precise location and support of the various cooperating
components of the tool head. These prior art tool heads, including the tool
heads
disclosed in the mentioned patents, often locate and support many of the
internal
cooperating components via the housing shells. These housing shells are
typically
fort'ned of plastic and are susceptible to flexing and twisting during
operation which
can adversely affect the cooperation between the components of the tool head,
thus
leading to jamming and/or failure of the tool head. Moreover, the practice of
locating
the various cooperating components of the tool head with respect to more than
one
reference structure (e.g., the two separate housing shells) allows the
manufacturing
tolerances associated with the individual components to be combined, which may
lead
to misalignment of the components.
There is therefore a need in the art for a tool head for use with an automatic
cable tie installation system which exhibits improved reliability, and reduced
jamming
and/or failure. The improved tool head should maintain an accurate and precise
relationship between the interacting and cooperating components of the tool
head
even when the tool head is subjected to such factors as flexing and twisting
of the
housing, thermal expansion and contraction of the housing, and opexational
wear.
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CA 02308885 2000-OS-19
SUMMARY OF THE INVENTION
The present invention, which addresses the needs of the prior art, relates to
a
tool head for installation of a cable tie about a bundle of elongate articles.
The tool
head is adapted for use with a remote dispenser, cable tie bandolier and cable
tie
S delivery hose of an automatic cable installation system. The cable tie
includes a head
and an elorxgate tail extending therefrom. The tool head includes a housing
including
first and second cooperating shells. The tool head futther includes a jaw
assembly for
grasping and directing the cable lie about the articles. The tool head further
includes a
tie passage communicating at one end with the cable tie delivery hose and at
the other
end with the jaw assembly whereby a cable tie supplied by the remote dispenser
is
delivered to the jaw assembly. The tool head further includes a tie tensioning
assembly for tensioning the cable tie upon installation of the cable tie about
the
elongate articles. The tie tensioning assembly includes a drive train and a
pawl gear
cut-off mechanism. Finally, the tool head includes a structurally rigid frame
sized for
location within the housing. The frame provides a fixed and common reference
structure independent of the housing to both support the pawl gear cut-off
mechanism
and to locate the pawl gear cut-off mechanism with respect to the drive train.
As a result, the present invention provides a tool head for use with an
automatic cable tie installation system which exhibits improved reliability,
and
reduced j amming and/or failure. The structurally rigid frame utilized in the
improved
tool head maintains an accurate and precise relationship between the
interacting and
cooperating components of the tool head even when the tool head is subjected
to such
CA 02308885 2004-09-27
factors as flexing and twisting of the housing, thermal expansion and
contraction of the
housing, and operational wear.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of an automatic cable tie installation system;
Figure 2 is an exploded perspective view of a prior art tool head;
Figure 2A is an enlarged detail of Figure 2;
Figure 3 is an exploded perspective view of a tool head in accordance with the
present
invention;
Figure 4 is a side elevational view of the tool head of Figure 3;
Figure 5 is a perspective view of the components of the tool head of Figure 3
removed
from their housing; and
Figure 6 is an exploded perspective view of the structurally rigid frame and
gear
assembly of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings, an automatic cable tie installation system 10
is shown
in Fig. 1. Installation system 10 includes a cable tie dispenser 12 (as
described in commonly-
owned U.S. Patent No. 6,279,620), a cable tie bandolier 14 (as described in
commonly-owned
U.S. Patent Nos. 5,934,465 and 5,967,316), a cable tie delivery hose 16 and a
tool head 18. In
operation, dispenser 12 severs the leading cable tie from bandolier 14, and
thereafter propels
the individual cable tie to the tool head via hose 16. The cable tie is
wrapped about a bundle
of articles positioned within the jaws, tensioned and is then subjected to a
cutting operation
whereby the excess portion of the cable tie tail is cut from the tensioned
cable tie.
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CA 02308885 2004-09-27
The operating components of a prior art tool head 50 are shown in Figs. 2 and
2A. In
this regard, the general operation of tool head 50 is well-known to those
skilled in the art. As
discussed hereinabove, U.S. Patent Nos. 4,498,506 and 4,790,225 disclose the
structure and
operation of a prior art tool head.
As will be appreciated by those skilled in the art, the housing of tool head
50, i.e.,
housing 52, is preferably formed from first and second cooperating shells 54a,
54b, such shells
being used to both support and locate the various components of the tool head.
Although it is
commercially desirable to form shells 54a, 54b from a plastic material, this
construction
introduces the possibility that housing 52 may flex and twist during operation
which can lead
to misalignment of the cooperating components, and ultimately jamming andlor
failure of the
tool head.
Tool head 50 includes jaw assembly 56, tie tensioning assembly 58, and a tie
passage
60 communicating at one end with cable tie delivery hose 16 and at the other
end with jaw
assembly 56 whereby a cable tie supplied by remote dispenser 12 is delivered
to the jaw
assembly.
Jaw assembly 56 includes in particular a top jaw 62, a bottom jaw 64, opposing
jaw-
mounting plates 66a, 66b, a trigger 68 connected to bottom jaw 64 for
CA 02308885 2000-OS-19
moving the bottom jaw beriveen an open position and a closed position, a push
rod 70
for moving top jaw 62 during installation of the cable tie about the bundle of
elongate
articles, a power-operated device 72 for powering said push rod, and a cutting
mechanism 73 suppozted between jaw-mounting plates 66a, 66b.
Tie tensioning assembly 58 includes in particular a drive train 74, a pawl
gear
cut-off mechanism 76 and a tension adjustment mechanism 78 pivotable about a
pivot
point 80. Cutting mechanism 73 cooperates with pawl gear cut-off mechanism 76
to
cut off any excess portion of the tai! from the tensioned cable tie.
In turn, drive train 74 includes a power-operated device 82, a driveshaft 84
coupled at one end to power operated device 82, a driveshaft bearing for
supporting
the other end of driveshaft 84 positioned within a housing 86, and a gear
assembly 88.
In turn, gear assembly 88 includes a first bevel gear 90 positioned at the end
of the
driveshaft 84, a second bevel gear 92 fixedly coupled to a shaft 94 and
located to
engage first bevel gear 90, a drive gear 96 also fixedly coupled to shaft 94,
a pair of
opposing bearings 98 for rotatably supporting shaft 90, and an idler gear 100
rotatably
coupled to a shaft 102 via a bearing 104 and located to cooperate with the
pawl gear
cut-off mechanism 76. As a result, rotary nnotion may be transmitted from
driveshaft
84 to the internal gear 1 OS (shown in hidden line in Fig. 2A) of pawl gear
cut-off
mechanism 76.
Gear assembly 88 further includes a pair of opposing gear-supporting plates
I06a, 106b, for supporting the mentioned gears therebetuieen. In this regard,
each of
plates 106a, 106b includes an aperture 108 sized to receive bearings 98, and
an
aperture 110 sized to receive the end of shaft 102. A microswitch 112 for
sensing the
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CA 02308885 2000-OS-19
presence of a cable tie is mounted on a bracket 114, which in turn is secured
to gear-
supporting plate 106a. Crear-supporting plates 106a, 106b also pivotally
support pawl
gear cut-off mechanism 76 via a pair of pivot pins 116. Each of gear-
supporting
plates 106a, 106b include a pair of apertures 11$ sized to receive the ends of
pivot
pins 116. Gear-supporting plates 106a, 106b, themselves are each separately
supported by shells 54a, 54b, respectively, of housing 52. Thus, flexing of
housing 52
can result in independent movement of each of driveshaft bearing 86, gear-
supporting
plate l Oda and gear-supporting plate 106b.
It will be appreciated that pawl gear cut-off mechanism 76 must be properly
aligned with jaw assembly 56 to receive the tail of the cable tie. Pawl gear
cut-off
mechanism 76 must also be properly aligned with microswitch 112 to ensure
smooth
operation of the tool head. Again, twisting and/or flexing of housing 52 may
produce
misalignment and/or movement of gear-supporting plates 106a, 106b (either
together
or independent of one another), thus causing misalignment of pawl gear out-off
mechanism 76 with respect to jaw assembly 56. Of course, this same twisting
and/or
flexing of housing S2 can produce movement and misalignment of the, jaw
assembly
itself. Finally, to ensure proper tensioning of the cable tie during
operation, the
location of tension adjustment mechanism 78 with respect to the pawl gear cut-
off
mechanism must be maintained.
Referring now to Figures 3-6, tool head 18 of the present invention
incorporates and utilizes a novel, structurally rigid mounting frame 120, also
referred
to as the '~nibody." Frame 120 preferably includes first and second locating
plates
122a, 122b. These plates are preferably machined metal plates which are
configured
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CA 02308885 2000-OS-19
to be securely fixed to one another via screws and/or bolts. When assembled,
the
unibody forms a structurally rigid frame which provides a fixed and common
reference structure independent of the housing to both support pawl gear cut-
off
mechanism 76 and to locate pawl gear cut-off mechanism 76 with respect to
drive
train 74. Preferably, the utuibody also supports a~ad locates the drive shaft
bearing,
supports and aligns the gear assembly, locates the jaw assembly, locates the
picot
point for the tension adjustment mechanism and locates the microswitch.
Each of locating places 122a, 122b includes a jaw-locating bracket 124a, lz4b
configured for securement to the jaw-mounting plates of the jaw assembly, thus
locating the jaw assembly with respect to the unibody, and in turn with
respect to the
pawl gear cut-off mechanism. In this regard, each of brackets 124x, 124b
includes a
pair of screw-receiving apertures 126 which are located to align with a pair
of
threaded apertures (not shown) provided in each of jaw-mounting plates 66a,
66b.
Locating plate 122a also includes an arm 128 haviu~g a aperture 130, which
provides the pivot point for the tension adjustment mechanists and which
receives a
pivot pin 132 (see Fig. 4). Accordingly, the location of pivot pin 132 is
fixed with
respect to pivot pins 116 (i.e., the pins that support pawl gear cut-off
mechanism 76),
thus ensuring proper cooperation between the tension adjustment mechanism and
the
pawl gear cut-off mechanism during all conditions of operation. Each of
locating
plates 122a, 122b further includes a threaded aperture 134 which receives a
screw
passing through housing shells 54a, 54b, respectively, thereby allowing shells
54a,
54b to be secured to locating plates 122a, -122b, respectively.
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CA 02308885 2000-OS-19
Referring now to Figure 6, locating plates 122a, 122b together provide a
driveshaft bearing housing 136, which supports the driveshaft bearing.
Locating plate
122a includes a pair of threaded apertures 138, while locating plate 122b
includes a
pair of screw-receiving apertures 140. Installation of screws 142 thus fixedly
secures
the locating plates to one another, and also secures the drive shaft bearing
within
bearing housing 136.
Thus, when the unibody is assembled within the tool head, the unibody forms
a structurally rigid frame which provides a common reference for locating the
various
operating components of the tool head. In contrast to the use of a plastic
housing for
locating the tool components, the unibody is preferably formed from machined
plates,
thus ensuring the accuracy at which the various attacbxnent points are
located. It will
be appreciated that the unibody's rigid structure ensures that all parts are
held in
proper orientation relative to each other, and prevents binding and
misalignment of
the moving components due to such factors as torque from the motors. thermal
expansion and contraction of the housing and operational wear. Thus, one
common
structure which is unaffected by flexing and/or twisting of the cool housing
locates
and supports the drive train, and also aligns the various subassemblies of the
tool head
with one another.
Although the unibody is described as including locating plate 122a, 122b, it
is
contemplated herein that the unibody can be formed as a sixigle integral unit.
This
may of course require certain modifications to the gear assembly, to the
coupling of
the pawl gear cut-off mechanism to the unibody, and to the drive shaft bearing
housing. However, the unibody (whether formed as a single unit or plural
pieces)
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provides a structurally rigid frame which locates and supports the various
components
of the tool head to prevent binding and t~isaligzunent of such components
during
operation,
It will be appreciated that the present invention has been described herein
with
reference to certain preferred or exemplary embodiments. The preferred or
exemplary
embodiments described herein may be modified, changed, added to or deviated
from
without departing from the intent, spirit and scope of the present invention,
and it is
intended that all such additions, modif rations, amendment and/or deviations
be
included within the scope of the followings claims.
