U.S. patent number RE31,541 [Application Number 06/132,732] was granted by the patent office on 1984-03-27 for webbed harnessing device.
This patent grant is currently assigned to Dennison Manufacturing Company. Invention is credited to William E. Wood.
United States Patent |
RE31,541 |
Wood |
March 27, 1984 |
Webbed harnessing device
Abstract
A harnessing device formed by a locking head and an attached
webbed strap. The head contains oppositely positioned locking tangs
in a guide channel that receives the strap after encirclement of
items to be harnessed. The tangs engage abutments of the webbed
strap for adjustable retention of the harnessed items. The strap is
advantageously molded of a stretch reorientable material.
Stretching produces a relatively thin and strengthened web which
resists penetration by the locking tangs and reduces the
possibility of failure by fracture or reverse rotation. The
inclusion of the relatively thin web also promotes homogeneity
during molding and avoids imperfections that can cause failure in
other types of straps.
Inventors: |
Wood; William E. (Hudson,
MA) |
Assignee: |
Dennison Manufacturing Company
(Framingham, MA)
|
Family
ID: |
26830677 |
Appl.
No.: |
06/132,732 |
Filed: |
March 24, 1980 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
801448 |
May 27, 1977 |
04137606 |
Feb 6, 1979 |
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Current U.S.
Class: |
24/16PB; 24/17AP;
24/30.5P; 264/294 |
Current CPC
Class: |
B65D
63/1081 (20130101); B65D 2563/106 (20130101); Y10T
24/1498 (20150115); Y10T 24/141 (20150115); Y10T
24/153 (20150115) |
Current International
Class: |
B65D
63/10 (20060101); B65D 063/00 () |
Field of
Search: |
;24/16PB,17AP,16R,73PB,3.5P ;264/294 ;248/74PB |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Sakran; Victor N.
Attorney, Agent or Firm: Kersey; George E.
Claims
What is claimed is:
1. A harnessing device comprising a head having an elongated guided
channel extending therethrough,
a pair of deflectable locking tangs within said head,
and a strap formed by a ladder structure with rungs which are
sequentially engaged by the locking tang when the strap is inserted
into the channel,
said ladder structure having a webbed portion substantially
constant thickness extending from each rung to reduce the force for
insertion of said strap into said channel and to limit the effect
of reverse thrust applied to said strap in causing reverse rotation
of said locking tang.
2. A harnessing device as defined in claim 1 wherein said device is
molded from a stretch-reorientable material and the webbed portions
of said strap is characterized by having permanent molecular
reorientation caused by stretching,
thereby to realize a relatively thin and strengthened member
extending from each rung of said ladder for reducing the force
required for insertion of said strap into said channel and limiting
failure of said locking tang by rotation due to reverse thrust
applied to said strap.
3. A harnessing device as defined in claim 1 wherein each rung of
said ladder strap includes abutments for engagement by said locking
tangs.
4. A harnessing device as defined in claim 1 wherein said webbed
portion extends from one rung to another,
thereby to permit the load applied to one of said rungs by said
locking tang to be distributed among other rungs.
5. A harnessing device as defined in claim 4 wherein said webbed
portion further extends between adjoining rails of said ladder
strap,
thereby to distribute the load applied by a locking tang in
engagement with a rung of said strap among not only adjoining rungs
but the associated structure thereof of said strap.
6. A harnessing device as defined in claim 1 wherein one end of
said strap is attached to said head at an angle with respect to the
axis of insertion of the other end of said strap to said
channel.
7. A harnessing device as defined in claim 1 wherein each of said
locking tangs has a tip that is proportioned to mate with abutments
in said rung.
8. A harnessing device as defined in claim 1 wherein said locking
tangs are integrally connected within said head by a neck portion
which is narrower than the extension of said locking tangs into
said channel,
thereby to facilitate the insertion of said strap into said
channel,
and said extension of said locking tangs form an angle no greater
than 30.degree. with respect to the axis of said channel,
thereby to increase the resistance of said locking tangs to failure
and reverse thrust rotation. .Iadd. 9. A harnessing device
comprising
a locking head having a channel therethrough,
a webbed strap attached to said head and having rungs joined to one
another by centrally depressed, stretchable webbing,
said strap being stretched with the spacing between rungs
controlled by the extent of stretching of said strap and the
stretching causing a reduction in the thinness of said webbing by a
prescribed amount according to the extent to which the strap is
stretched, said rungs having a profile controlled by stretching a
plurality of segments, including perpendicular segments that are
caused to depart from their initial perpendicularity by an amount
that is controlled by the extent to which the strap is
stretched,
said locking head further including a locking pawl in said head for
securing said strap therein. .Iaddend..Iadd. 10. Apparatus as
defined in claim 9 wherein said pawl includes a inclined surface
that forms an acute angle with the axis of insertion of said strap.
.Iaddend..Iadd. 11. Apparatus as defined in claim 9 wherein said
locking head includes a channel for the entry of said strap having
side ledges therefore therein. .Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to the harnessing of the items and more
particularly to the realization of efficient, low-cost, high
strength harnessing devices which are easy to use.
Harnessing devices are widely used for the bundling of objects.
Such devices are typically formed with a serrated strap that is
fitted to an apertured head containing an internal pawl or locking
tang that engages the serrations of the strap. Other harnessing
device are in the form of an apertured strap fitted to a
buckle-like head, with a tongue that enters the apertures of the
strap.
Harnessing devices with serrated straps have the disadvantage of
being only as secure as their pawls. Where the items that are
harnessed are heavy or are subjected to rough handling, the items
often become accidentally released, for example, by failure of the
pawls. Attempts have been made to strengthen serrated strap
devices, but this has resulted in considerable complexity without
achieving the desired end result of providing security against
accidental release of the harnessed items. Similar objections apply
to harnessing devices with buckle-like heads. In these devices, a
tongue which enters the strap apertures rests against the head of
the buckle near its opening and is deflected by the strap. The
tongue is typically a cantilever attachment to the buckle-like
head, which tends to be unduly stiff in the direction of forward
thrust during harnessing, and insufficiently stiff in the direction
of reverse thrust applied by the strap because of the harnessed
items. In addition the tongue is exposed to external interferences
that can cause an accidental release of the harnessed items.
Representative harnessing devices are disclosed in U.S. Pat. Nos.
515,747; 2,977,145; 3,030,131; 3,106,028; 3,127,648; 3,140,139;
3,189,961; 3,339,246; 3,368,247; 3,486,201; 3,457,598; 3,537,146;
U.S. Pat. No. Re 26,492; U.S. Pat. Nos. 3,542,321; 3,588,962;
3,598,442; 3,627,300; 3,654,669; 3,660,869; 3,731,347; 3,816,878;
3,840,256.
In order to avoid and overcome many of the difficulties associated
with the foregoing kinds of harnessing devices, ladder straps and
associated locking tangs have been developed of the kind disclosed
in U.S. Pat. No. 3,766,608, which issued Oct. 23, 1973. The ladder
strap device represents a significant improvement over the serrated
strap and other harnessing devices. It can accomplish substantially
the same functions as a serrated strap device at a considerably
lower cost. The ladder strap can be produced with a significant
saving in material and can be stretched to reorient its molecular
structure and strengthen its constituents without strap distortion,
as would occur if an attempt were made to stretch a serrated
strap.
Notwithstanding its advantages, however, the ladder strap device
requires a relatively massive locking tang or pawl in order to
avoid failure from the reverse thrust of the items being harnessed.
There are two kinds of pawl failure. The first is a loading failure
by virtue of fracture of the pawl near its base. The second is
"pawl pull". Here the reverse thrust produces a reverse rotation of
the tang that is so great that the strap is released.
In addition the use of cross linked members to form the ladder
portion of the strap requires care in molding to properly fill the
mold and can also require special attention to the molding
materials in order to achieve a satisfactory end product.
Accordingly, it is an object of the invention to provide for the
secure harnessing of items. A related object is to achieve secure
harnessing without the need for a complex harness
configuration.
A further object of the invention is to reduce the strength
characteristics needed for a locking pawl in a harnessing device of
the ladder type. A related object is to achieve a less stringent
locking pawl requirement while retaining the advantages of a ladder
strap.
Another object of the invention is to reduce the material and
molding requirements associated with the filling of molds and the
production of harnessing devices. A related object is to reduce
molding and material requirements in the manufacture of ladder
strap harnessing devices.
SUMMARY OF THE INVENTION
In accomplishing the foregoing and related objects the invention
provides a harnessing device with a head that contains a guide
channel and opposed locking tangs. A strap in the form of a ladder
structure is used to encircle the items to be harnessed and it
extends at an angle from the locking head with respect to its
longitudinal channel. Each active rung of the strap contains
abutments for engaging the locking tangs at a position between the
center line of the strap and the outer periphery of the rung. The
strap additionally is webbed between the rungs. The webbing reduces
the force required for insertion of the strap into the head and
limits the tendency of thrust applied to the strap from fracturing
the pawl or producing counter rotation.
The inclusion of webbing further permits the strap to be molded
with an improved filling characteristic. The webbing region of the
mold serves as a channel for the flow of the molding material to
the rungs thus assuring complete filling of each rung cavity. The
webbing also limits the occurrence of such imperfections as voids,
"nits" and "cold shuts". Voids are produced by gaseous bubbles
during turbulent flow of the mold mixture. A "nit" is an
imperfection in the surface of the molded part particularly a
surface discontinuity in the nature of a stress crack. The webbing
produces strengthening of the overall structure and is stretchable
in the case of molecular reorientable materials to provide
increased strength per unit area. A "cold shut" is a molding
discontinuity that occurs because of premature chilling which forms
a skin-like layer of material that is not integrally tied to the
remainder of the structure. The additional flow of material because
of the webbing channel permits the completion of filling before
chilling takes place.
DESCRIPTION OF THE DRAWINGS
Other aspects of the invention will become apparent after
considering several illustrative embodiments taken in conjunction
with the drawings in which:
FIG. 1A is a perspective view of a webbed harnessing device in
accordance with the invention;
FIG. 1B is a partial cross sectional view of the device of FIG.
1A;
FIG. 2A is a plan view of a portion of the device of FIGS. 1A and
1B;
FIG. 2B is a sectional view of FIG. 2A;
FIG. 3A is a plan view of an unstretched version of the device of
FIG. 2A; and
FIG. 3B is a sectional view of FIG. 3A.
DETAILED DESCRIPTION
As shown in FIG. 1A, a webbed harnessing device 10 in accordance
with the invention includes a head 11 and an attached strap 12. The
strap 12 is in the form of a ladder structure with side rails 12s-1
and 12s-2 and rungs 12r. Each region between adjoining rungs
includes relatively thin webbing 12w. The free end 12f of the strap
12 is insertable into a channel 11c of the head 11 to engage
deflectable locking tangs or pawls 11t-1 and 11t-2.
In the sectional view of FIG. 1B, the locking tangs 11t-1 and 11t-2
are shown in engagement with abutments 12-b-1 and 12b-2 of a rung
12r. Because of the webbing 12w each of the locking tangs 11t-1 and
11t-2 cannot move beyond the center line A of the channel 11c. This
facilitates the insertion of the strap 12 since only a slight
deflection of the locking tangs 11t-1 and 11t-2 is needed to clear
the protuberance 12p of the succeeding rung 12r'. If the webbing
12w were omitted it would be possible for the locking tangs 11t-1
and 11t-2 to move through a large arc extending from a flange 11f
to the lower wall 11w. The web 12w is of a substantially constant
thickness which is sufficient to resist penetration by the locking
tangs 11t-1 and 11t-2 as the strap is drawn by successive abutments
over the tips 11p of each tang. When the web is strengthened by
stretching after molding it can become translucent, and even
transparent, even if the remainder of the device is not. A suitable
thickness for the web has been found to be between 2 and 7 mils,
with the range from 3 to 5 mils being preferred.
It is also desirable for the thickness of the web to be related to
the thickness of the associated rungs. A suitable web-rung ratio is
in the range from about 1:2 to about 1:6 with the range of about
1:3 to 1:5 being preferred. The spacing of the rungs along the
straps is desirably such that at least one of the rungs 12r is
included within the head 11, although the rungs may be more closely
spaced in order to provide a closer control over the closure about
the articles being encircled.
Since the presence of the web prevents the locking tang 11t from
adopting an angle of inclination with respect to the wall 11w
greater than 45.degree., the tang may be significantly reduced in
mass for a prescribed resistance to tang failure and reverse tang
pull. The particular tang 11t of FIG. 1B includes a tip 11p which
is proportioned to provide substantial contact engagement with each
abutment 12b. In addition the tang 11t includes a neck portion 11n
which is narrower than the extension of the tang into the channel
11c. This further facilitates insertion of the strap 12 into the
channel. The particular tang 11t of FIG. 1B forms an angle of less
than 30.degree. with respect to the axis A to increase the
resistance of the tang 11t to failure and reverse pull.
The head 11 additionally includes a central flange 11f which
provides a cam surface directly opposite the position of contact
between the engaged rung 12r and the locking tangs 11t-1 and 11t-2.
The flange 11f is flanked by side channels 11s-1 and 11s-2 (FIG.
1A) above the positions occupied by the side rails 12s-1 and 12s-2.
This increases the degree of contact between the strap and the tang
and consequently helps prevent failure by reverse pawl pull.
The provision of the webbing 12w facilitates production of the
device 10 with improved operating, molding and stretching
characteristics. Because of the web 12w the material inserted into
the mold, which is advantageously accomplished by injection
molding, has an enlarged channel for the flow of material, as
compared with the standard ladder structure. The result is that
imperfections that often attend molding such as cold shuts, voids
and nit marks are either eliminated or significantly reduced in
extent.
In those cases where the strap 12 is to be stretched it is
desirable for the material to be of molecular reorientable type,
such as nylon, polypropylene, polyester, urethane, or the like.
This material, upon stretching, not only reduces the volume per
unit length of the strap, as indicated in FIGS. 2A and 2B but also
provides enhanced physical properties. For example there is
increased strength in tensile and shear strength.
The configuration of a portion 22 of a strap stretched in
accordance with the invention is set forth in plan view in FIG. 2A
and in section in FIG. 2B. The portion 22 includes side rails 22s-1
and 22s-2 and rungs 22r. A stretched web 22w extends between each
pair of adjoining rungs. The stretching produces scalloped edges on
the strap 22, with the side rails 22s-1 and 22s-2 being reduced in
diameter between adjoining rungs 22r. The upper portion 22r-1 of
each rung 22r in FIG. 2B can be carried by the central flange
member 11f shown in FIG. 1B; the lower portion 22r-1 contains
abutments 22b for engagement by the locking tang 11t of FIG.
1B.
The device 10 may also be used with an unstretched strap, in the
form removed from the mold, in which case a representative portion
22' of the unstretched strap is as shown in FIGS. 3A and 3B. The
spacing between adjoining rungs 22r' can be controlled by
controlling the extent of strap stretching.
The webbing 22w and 22w' is shown as filling the entire interval
between each pair of adjoining rungs, but it will be understood
that the web may extend only a portion of the inter-rung distance
and may be detached from the side rails.
While various aspects of the invention have been set forth by the
drawings and the specifications, 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.
* * * * *