US20030186024A1

US20030186024A1 - Plastic tie system

Info

Publication number: US20030186024A1
Application number: US10/105,357
Authority: US
Inventors: Roger Walsh
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-03-26
Filing date: 2002-03-26
Publication date: 2003-10-02

Abstract

A low-cost, light-weight, high strength, resilent plastic strapping tie is of simple, substantially rectangular extruded form, used in combination with slip-on adjustable tie attachment means. One laterally applied/removed slip-on attachment has a spring ring coil, for applying anywhere along the length of a tie, or to couple ties together, including embodiments having a hook portion to secure the tie to a tie-down point. The subject strapping tie may be knotted, and may be relatively readily unknotted. Ties of polyolefin and polyurethane can have ultimate tensile strength of up to 8,000 pounds per square inch of strap cross section; with a dog-bone, substantially rectangular cross-sectional profile with enlarged rounded edges. The range of small, lightweight attachment fittings includes a mini shock cord equipped with a hook.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO MICROFICHE APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

1. This invention is directed to a plastic tie system, using semi-oriented polyolefins and polyurethanes that provide great strength, by way of ties of various sections, including straps suitable for tying down loads, and including a load tie system incorporating a resilient tying strap, and convenient strap attachment means.

2. Wide use is made of both natural and synthetic materials for securing loads, tying objects down, etc. Examples include the use of plastic sheet wrap, wound by way of multiple layers, to secure bulk loads upon wooden pallets; high strength braided nylon straps, used as pull-downs on tractor trailers, to secure heavy loads to the trailer bed; the use of high strength strapping such as stainless steel and mild steel strapping with crimped or pinned fastenings; stiff nylon ribbon strap for securing about packages, the strap having its ends secured by gluing or stapling; and bungee cords, used to tension tarpaulins or to resiliently secure load elements of various forms.

Referring to the latter two examples, in the case of nylon strapping, the strapping is extremely strong, but substantially inelastic, and has sharp edges with a tendency to cut into the sides, and more particularly the edges of packages. Fastening of the ends of the nylon strapping usually also requires use of a heat sealing device, to secure the strap by welding the ends to each other, or use of a commercial stapler for that purpose.

In the case of Bungee (™)cords, these usually have an elastic cylindrical rubber core, possessing a somewhat low tensile strength of about 1200 pounds per square inch.

A woven protective “cloth” cover is provided to diminish abrasion of the rubber, and reduce susceptibility of the rubber to ultra-violet degradation, while protecting the user against discolouration of hands, clothing and objects by the black rubber of the cord core, which is highly prone to such marking.

The Bungee cord attachment ends generally comprise stiff wire hooks, each end of the cord being knotted doubled over and trapped in a wound-wire conical end portion of the base of the respective hook. These cord ends are known on occasion to escape from the hook end, releasing the load.

The Bungee cord structure is complex, relatively expensive, and subject to failure, due to overload or to becoming disassembled. A further disadvantage of the Bungee cord as a load restraint system is the necessity of having to make the cords up in fixed lengths, the attachment ends and cloth covering being unsuited to adjusting cord length in the field.

This also is the case for EPDM rubber straps, which have moulded end recesses to receive their hook ends, and are not suitable for convenient shortening. Ecologically, rubber is not suitable for direct re-cycling, and it breaks down into toxic by-products as it degrades over time. Aspects of the prior art are to be found in U.S. Pat. Nos. 3,800,008 Starkweather, March 1974, —polymer strapping; 4,513,063 Hashi et al, April 1985, bungee-type cord; 5,525,391 Dipede et al, polyethylene teraphthalate strapping.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a low-cost, light-weight, high strength, resilent plastic tie and strapping of simple, substantially rectangular extruded form.

In a preferred embodiment the strapping is used in combination with adjustable slip-on attachments, which can be attached anywhere along the length of a tie, thus enabling adjustment of the effective length of the strapping to form a tie having a selected and adjustable length characteristic.

The slip-on attachment embodiments slip sideways onto and off the strap, and are thus readily attachable and detachable from the strapping, and do not require end-threading. This also enables use of a long strap for a short tie, without having to have recourse to cutting the strap to length, or manipulating an undue length of strap through an attachment fitting.

One slip-on attachment, a spiral ring embodiment, may serve to secure the strap to a tie-down point.

An embodiment of the spiral ring slip-on attachment may include a resiliently retractable and deployable hook portion, to enable anchoring a strap or tie in secured relation to a hold-fast. The slip-on attachment may also be used to join two lengths of the strapping, to readily form a strap or tie of extended length.

Embodiments of the subject strapping may be extruded in a wide range of widths and thicknesses. For straps having a thicknesses of up to about one inch thick, the strapping is fairly readily hand tieable, and can be directly knotted and also untied, enabling its direct securement to, and ready removal from a suitable tie point.

A range of suitable elastomers are available, depending upon the particular load range and working extensibility required, being selected from thermosetting polyolefins and polyurethanes, which can be readily manufactured by way of extrusion.

The preferred polyurethane materials are the polyether and the polyester elastomers, having a tensile strength in the range of 5,000 pounds per square inch, and greater.

A Dow Chemicals Inc. polyester-based polyurethane such as DOW 2102-90 AE possesses good, inherent resistance to U/V degradation.

The subject strapping and ties materials are readily extruded as a continuous, i.e. endless strap or tie.

One tie cross-sectional embodiment that has proven to be of great interest and practical use has modestly enlarged edge portions, which may be of substantially arcuate form, to give a so-called “dog bone” cross section profile.

One unusual and unexpected aspect of polyurethane strapping has been found, in the unduly strong mutual adhesion that occurs between adjoining, lightly compressed faces of a tie, when wrapped about a spiral ring or other form of attachment fitting in face-to-face mutually compressed relation, or when knotted. The unduly high degree of “stiction” thus developed appears to be due to the molecular structure of the material.

In one embodiment a strap was initially extruded as a thin-walled somewhat flattened tube, and the tube wall then allowed to fully collapse into flattened, mutually bonded relation, thereby forming a unitary, substantially solid strap having radiused edges.

The somewhat enlarged and radiused edges appear to play a role in the unusual and advantageous handling characteristics of the strapping tie, particularly with regard to knotting and un-knotting. Hand-tied knots that have been subject to load, have been found to be readily untied. When tied and under load, the knots do not appear to be subject to undue tightening, presumably due to the self-gripping nature of the material, possibly aided by the cross-section profile of the strapping.

The polyurethanes, which has natural U/V resistance, may readily be further U/V stabilized during extrusion, with an ultraviolet resistive surface.

A range of suitable thermoplastic materials exists, in a wide range of cost and ultimate tensile strengths, which can be extruded in the desired strapping form. These include the polyolefins and polyether-based and polyester-based elastomers, including most, if not all polyurethanes.

The polyurethanes may be extruded in the Shore A durometer range of 35 to 100, having ultimate tensile strength in the range 600-8,000 psi.

Owing to its semi-ribbon form, the strap can be readily, compactly and stably coiled for storage, dispensing and transportation.

The strap or tie is relatively low cost and has a wide range of sizes and uses, including horticulture, where the comparatively large contact surface area minimizes local surface pressure, and hence suits use as ties in tree and bush tie-back and securement.

Also, the elasticity of the strapping, with the capability of up to 600% elongation, ensures that no damage can occur due to growth of the organism.

Use of the polyolefin and polyurethane groups of the subject strapping with loads that are subject to shifting, compression or swelling, benefits greatly from the large extension range the plastics offer. Thus, by applying the tensile loading to achieve gross stretching of the tie, to say 400% extension, then the capability of further extending, to as much as 600% of its initial length, or of correspondingly shortening elastically, while maintaining an effective range of tension upon the load, means that the load restraint force will remain substantially applied, whether the load expands or contracts, within the residual, wide available elastic limits of the tie.

An important aspect of the use of polyurethane in the role of a strapping tie is that it is recyclable.

In view of the potentially wide usage of polyurethane ties in accordance with this invention, and the extreme resistance of polyurethane to natural degredation, the suitability of polyurethane for recycling is of significant importance to the environment; also, its degradation by-products are non-toxic. It has been found that the strength and elastic memory characteristics of the selected group of polyolefin and polyurethane plastics can be dramatically improved by mechanical conditioning in order to achieve molecular semi-orientation of the plastic.

In contrast to molecular semi-orientation, full molecular orientation of these plastics, while greatly enhancing the ultimate strength of the material, also results in diminished elastic memory, whereas semi-orientation results in good elastic memory.

Full molecular orientation is carried out at high temperature, usually about 50 F. degrees less than the extrusion temperature. This normally requires reheating of the extrudate, as in an oven, prior to carrying out the orientation process.

Semi-molecular orientation is a so-called “cold” process, wherein the mechanical processing of the extrudate is performed while the extrudate is still warm, after its passage through a cooling bath.

The mechanical orientation process consists of stretching the plastic extrudate, by running a set of pinch rolls significantly faster than the extruder take-off rolls.

For full orientation the pinch rolls run from as much as about six to nine times faster than the take-off rolls, with the plastic at a high temperature, close to that of the extrusion temperature.

For semi-orientation, the drawer rolls run usually at between about two and a half to three times faster than the take-off puller rolls, with the plastic in a warm condition, being referred to, however as a cold process.

The cold extension of the extrudate can be effected directly by use of the storage drum, the speed of which is controlled to provide the necessary threefold extension of the extrudate

The condition of a plastic strand, as to whether or not it is semi-orientated, can be determined by use of an INTRON (™) tensile tester, as used for ASTM tests on plastics. The instrument enables measurement of the load applied to the test piece, the consequent elongation, and the point at which plastic deformation commences.

The effect provided by the approximately 1,000% increase in strength and elasticity produced by the semi-orientation process is so marked, the determination of the state of a plastic sample is readily made.

As an example of the effects of carrying out the semi-orientation process, taking an extruded strand of polyurethane that is subjected to the semi-orientation process, having sensibly the same final cross section as a strand of rubber band, and comparing it with a strand of like section of rubber band, and with an untreated extrudate of the same urethane material and section:

1. the rubber band strand had a breaking load of about one pound;

2. the untreated polyurethane strand had a breaking load of about five pounds;

3. the polyurethane strand subject to the semi-orientation process has a breaking load of fifty pounds.

In a mini shock-cord embodiment of the present invention, a small shock cord plastic hook, Part No.605-3250 manufactured by ITW Nexus of Desplaines, Ill., having a breaking strength of 125 lbs is combined with a semi-oriented urethane cord of 150 to 175 mil diameter (0.150-0.175 inches), having a breaking strength in excess of 100 lbs.

The hook is dimensioned to accept a ¼ inch filament or cord.

In another shock-cord embodiment, a dog-bone profiled urethane cord is doubled over at its end, and inserted into the open end of the ITW Nexus hook, and locked into place by the locking sleeve. This profiled cord, having a width of about 200 to 300 mil by 50 mil thick gives a breaking load in excess of 100 lbs.

In regard to the provision of attachments, an attachment spring ring may comprise a number of embodiments, one of which has an open hook-end that can be used to secure the attachment to an anchor point; a split-ring, helical portion serving to secure the strapping. The open hook-end may be fixed, or it may be deployed from, or retracted to the ring.

A second spiral spring ring embodiment, in threee versions, has an extended re-entrant hook portion, the free end of which can be freed from an initial engaged condition within the coils of the spiral ring, and deployed to open the hook, to engage other items, such as an anchor point. The third version hooks over the split spiral rings, by way of a keeper-hook.

A third spiral spring ring embodiment has a hook portion forming a closed arc, the free hook end being pressed in closing relation against the outside surface of the residual closed spiral rings. This has the appearance of a closed figure “6”.

An “S” shaped attachment hook, which also can be laterally applied, may have a spring keeper tongue that can be engaged with a retaining bent, to lock the hook in a closed condition, so as to retain the tie strap or straps in laterally inserted, secured relation.

Another S-hook embodiment may have a plastic tube that is slid along a first free-end portion of the hook, to bridge the side gap of the hook, the free end of the plastic tube being engaged in locking relation with a second free-end of the hook

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Certain embodiments of the present invention are described by way of illustration, without limitation of the invention thereto, other than as set forth in the accompanying claims, reference being made to the accompanying drawings, wherein: [0056]
FIG. 1 is an enlarged end view of a strapping tie embodiment in accordance with the present invention; [0057]
FIG. 2 is a diagramatic sketch of a coil of the FIG. 1 strapping tie embodiment; [0058]
FIG. 3 is a plan view of a spiral-ring hooked strapping attachment for use with the subject system; [0059]
FIG. 4 is a side elevation of the FIG. 3 embodiment, taken in the direction of the arrow [0060] 4.
FIG. 5 is a plan view a second embodiment spiral ring hooked strapping attachment, [0061]
FIG. 6 is a section taken at [0062] 6-6 of FIG. 5;
FIG. 7 is a section view similar to FIG. 6, showing an alternative hook-end portion for the FIG. 5 embodiment; [0063]
FIG. 8 is a plan view of a third embodiment spiral ring hooked strapping attachment; [0064]
FIG. 9 is a side elevation of the FIG. 8 embodiment, taken in the direction of the arrow [0065] 9;
FIG. 10 is a top-front perspective view of a spiral ring anchor, having a keeper-hook at the hook free-end; [0066]
FIG. 11 is a schematic block diagram of the subject molecular semi-orientation process; [0067]
FIG. 12 is a side view of an S-hook in accordance with the present invention, having a keeper of plastic tube, shown in the open, unsecured condition; [0068]
FIG. 13 shows the FIG. 12 embodiment with the the keeper in an engaged condition; [0069]
FIG. 14 shows an alternative manner of stowing the keeper; [0070]
FIG. 15 shows a mini shock-cord and associated plastic hook in pre-assembled relation; and, [0071]
FIG. 16 is an end view, as if from the [0072] direction 16, of an S-hook embodiment, similar to FIG. 14, but wherein the hook portion is cranked upwardly at right-angles to the S-portion of the attachment.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the “dog-bone” cross-section of the [0073] tie 20 has a high width to thickness ratio, illustrated as being about 17 to 1. The web portion 22 terminates in thickened end portions 24, illustrated as being substantially cylindrical.
In one embodiment the [0074] tie 20 has a width of 0.625 inches (⅝″), with the web 22 having a thickness of 0.035 inches, the rounded edge portions 24 being of about 0.045 inches diameter.
In FIG. 2, the illustrated three-inch diameter of the [0075] coil 26 is the actual diameter of a 20-foot coil of the ⅝″ wide tie down strap embodiment. Referring to FIGS. 3 and 4, the spiral ring-hook fastener 30 has a hook portion 32 extending from a triple spiral-ring body portion 34. A tapered sleeve portion 36 slidably enfolds the hook wire portion 32 and the adjoining one of the spiral rings. The sleeve portion 36 is shown in part section.
Engagement, by sliding displacement of the [0076] sleeve 36 towards the hook portion 32 causes wrapping of the hook portion 32 in coiled relation with the body portion 34.
Retraction of the [0077] sleeve portion 36 permits extension of the hook portion 32 to a deployed, operational hooking configuration.
The remote end of the [0078] hook wire portion 32 has a keeper 38, which protects the sharp end of the hook portion 32 and also serves to retain the hook portion 32 within the sleeve 36, when the sleeve 36 is engaged.
The [0079] ring body portion 34 has adjoining coil portions 38, 40, the latter coil 40 being spiralled (i.e. of smaller diameter) and having a tapered end 42.
The tapered inner end [0080] 42 of the fastener 30 facilitates the ready insertion of an end, or of a loop of the tie 20 into engaged relation with the ring turns of the fastener 30.
Referring to FIGS. 5 and 6, these illustrate a two spiral-[0081] coil ring anchor 50 having two ring portions 52, 54 and an extended hook portion 56. The remote bight portion 58 of the hook portion 56 is of reduced diameter.
The [0082] proximal end 60 of hook portion 56 has an upset cam-shaped portion 62, which engages the adjoining inside surfaces of the ring portions 52, 54. This resists the forcing open of the hook portion 56 under load.
The [0083] cam shape portion 62 is pointed, to facilitate its entry between the ring portions 52, 54, by spreading them apart
FIG. 7 shows an alternative, cranked [0084] toe portion 64 for the proximal end 60 of hook portion 56. This cranked toe portion 64 is inclined outwardly, such that anchor forces acting upon the hook portion 56 will tend to wedge the toe portion 64 within the rings 52, 54.
FIG. 10 shows a [0085] ring anchor 65 having a keeper-hook portion 67 in the engaged position, to secure the proximal end portion of the book 56′ positively locked.
Referring to FIGS. 8 and 9, these illustrate a two spiral-[0086] coil ring anchor 66 having two spiral ring portions 68, 70 and an extended hook portion 72 The hook portion 72 is shown as being of substantially the same diameter as the ring portions 68, 70. The proximal end 64″ of hook portion 72 has a shaped end, which presses against the adjoining outer surfaces of the ring portions 68, 70. The use of the spiral ring hook embodiments for other purposes is contemplated.
The external leverage afforded by the length of the respective hook portions has been found to provide facilitated access to spreading apart the coils of the spiral rings. [0087]
Embodiments of spiral ring-hooks, having ring diameters of about one and one half inches, made of 0.080-inch diameter stainless, spring steel wire, is very effective when used in combination with plastic strapping tie embodiments in accordance with the invention. [0088]
The use of a 0.060 inch diameter galvanized spring steel wire has been found to serve effectively for light duty [0089]
Referring to FIG. 11, the polyolefin and subject polyurethane plastic materials are melted and extruded under pressure through a suitably shaped and sized die. [0090]
In mechanically treating the extruded plastic to achieve semi-orientation, it will be understood that if the drawer rolls are run at three times the speed of the upstream puller rolls, then the extruded section will be reduced in size as a consequence. However, owing to the enhanced elasticity of the plastic, resulting from the semi-orientation process, the reduction in cross section is not proportional to the increase in speed provided by the drawer rolls. [0091]
While considerable drawing-down takes place, this change is mitigated by the enhanced elasticity of the semi-oriented plastic. [0092]
In light of this, and knowing the desired load capacity, then the cross-section dimensions of the die are correspondingly increased, such that the desired, reduced section will be ultimately obtained when the semi-orientation is completed. [0093]
The puller rolls assist the passage of the extrudate from the die, after having passed through a cooling bath, where the temperature of the extruded section is significantly reduced, to a desired level. [0094]
The drawer rolls, operating usually at a speed between two and three times that of the puller rolls, draws out the section, while also partially orienting the molecular structure with the main axis of the extrudate. This partial orientation increases the ultimate strength of the material by as much as a factor of ten, while also significantly enhancing the elastic memory. [0095]
Turning to FIGS. 12, 13 and [0096] 14, a substantially planar S-hook attachment 80 has a hook portion 82 and an S-portion 84 to receive a tie strap or straps in interwoven buckled relation therewith.
A hollow [0097] plastic keeper tube 86 is shown in an open position in FIGS. 12 and 14, and in an engaged, operative condition in FIG. 13. However, the tie strap(s) have been omitted for purposes of clarity.
In the FIG. 16, S-[0098] hook embodiment 81, the hook portion 82 is cranked upwardly substantially at rightangles to the plane of the S-portion 84. The S-portion 84 is shown slightly in perspective, to better illustrate and identify its presence.
The FIG. 16 embodiment with the cranked [0099] hook 82 has functional advantages, in that the access for engaging the straps is enhanced; but much more importantly, the hook is much more readily engaged with a strongpoint or hook tie-down in the bed of a truck.
Referring to FIG. 15, a mini-hook [0100] 90 has an attachment portion 92 that contains two convergent trapping blades 94, and a tubular keeper 96 that engages the trapping blades 94, to secure them in engaged relation with the doubled end of miniature tie strap 98, which is pushed home, past the blades 94, and the keeper 96 then slid into place, to lock-up the assembly. This provides a mini shock cord, having a load capacity in excess of one hundred pounds, and with high elastic recovery, as discussed above, but being exceptionally light and non-bulky
It will be understood by those skilled in the art that variations and/or modifications of the present invention may be made, within the scope of the present claims. [0101]
The strapping can be made from recycled but unused polyurethane, at low, competitive cost, without sacrifice of quality. [0102]

Claims

1. A light-weight, high strength, thermo-plastic elastomer strapping tie of extruded form, selected from the group consisting of polyolefin and polyurethane plastic, wherein said extruded form is molecularly semi-oriented, possessing high elastic recovery and an ultimate tensile strength in the range of 6,000 to 8,000 pounds per square inch, in use to enable utilization thereof as a high strength elastic tie.

2. The strappimg as set forth in claim 1, said polyurethane plastic being selected from the group consisting of polyester and polyether thermosetting elastomers having an original tensile strength in the range of about 600 to about 8,000 p.s.i.

3. The strappimg as set forth in claim 1, said extruded form being substantially rectangular and having a width to thickness ratio in the range from 6 to 1 to 25 to 1.

4. The strappimg as set forth in claim 1, said extruded form being substantially cylindrical.

5. The strappimg as set forth in claim 1, said extruded form having a dog-bone section profile with enlarged edge portions.

6. The strappimg tie as set forth in claim 1, in combination with tie attachment means, enabling ready attachment of the strapping to an attachment point.

7. The combination as set forth in claim 6, wherein said strapping tie comprises a first length of said strapping, and said tie attachment means comprises a separable spring ring device.

8. The combination as set forth in claim 6, wherein said strapping tie comprises a first length of said strapping, and said tie attachment means comprises an S-hook portion, providing in use for lateral sliding insertion of said strapping tie in engaging relation with said S-hook portion.

9. A unitary hook fastening device having an S-shaped portion to receive a strapping tie in secured, inserted relation therewith, and a hook portion extending therefrom, for securing the device to a strong-point.

10. The unitary hook fastening device as set forth in claim 10, including a hook portion projecting substantially at rightangles from said S-hook portion, in use to facilitate access thereto.

11. The unitary hook fastening device as set forth in claim 9, including a keeper tube slidably mounted upon said hook portion, being movable into engaging relation with said S-shaped portion, whereby said strapping tie is retained in engaged relation with said S-shaped portion.

12. The combination as set forth in claim 7, said spring ring device having a resilient, re-entrant hook distal end portion engageable with an arcuate ring portion of said device, by entry within said arcuate ring portion.

13. A method of making a semi-oriented plastic strap tie, selected from the group consisting of polyolefin and polyurethane plastics, including the steps of extruding the plastic through a die of predetermined size and profile; cooling the extruded plastic; passing the cooled plastic through a first take-off roll nip running at a first speed; and passing the cooled plastic through a second puller roll nip running at a second, higher speed, wherein said second speed is two to three times faster than said first speed, to stretch, reduce and semi-orient the molecular structure of said strap tie.

14. The method as set forth in claim 13, said polyurethane plastic being selected from the group consisting of polyester and polyether thermosetting elastomers.