US3409951A - Device for anchoring a textile cable - Google Patents

Description

Nov. 12, 1968 G. MORIERAS DEVICE FOR ANCHORING A TEXTILE CABLE Filed Nov. 7, 1966 2 Sheets-Sheet 1 FIG. I.

A llorncys Nov. 12, 1968 G. MORIERAS DEVICE FOR ANCHORING A TEXTILE CABLE 2 SheetsSheet a Filed Nov. '7, 1966 mum rm? AB HT/Y 05/5541 United States Patent 3,409,951 DEVICE FOR ANCHORING A TEXTILE CABLE Gilbert Morieras, Lyon, France, assignor to Societe Rhodiaceta, Paris, France, a French body corporate Filed Nov. 7, 1966, Ser. No. 592,610 Claims priority, application France, Nov. 15, 1965,

Claims. to]. 24-123 ABSTRACT OF THE DISCLOSURE Anchoring device for a textile cable under tension comprising a core formed by a bundle of parallel filaments and an external envelope covering the core. The device is constituted exteriorly by a rigid sleeve of tapering form and interiorly by a bung also of tapering form which has a common directrix with the sleeve and in which the end of the cable is fixed in any appropriate way. The interior apical angle of the sleeve is less than the apical angle of the bung. The device is particularly advantageous for anchoring cables made of synthetic textile materials such as polyamides, polyesters and polyolefins.

This invention relates to an anchoring device, that is to say a device for attachment to a fixed point, of a textile article operating under tension; such articles include cords, cables, straps, slings, etc., which for simplicity will be described by the single term cable in the following description.

For some years metallic cables have to some extent been replaced by cables made from synthetic textile filaments, for example polyamide or polyester filaments. Thus some textile cables have been made which, for a given weight per metre, have a higher resistance to break than have steel cables, and this should allow them to be used advantageously as traction elements (e.g. as cables for masts, catenaries, buoys, ships slings, etc.). Unfortunately textile cables have not undergone such development in this field of application, largely as the result of the absence of suitable means for anchoring them.

To form an anchoring device with a steel cable, the wires at the end of the cable are untwisted and each Wire is individually folded into the shape of a loop; the assembly of wires is then opened up and placed in a sleeve the internal shape of which is genenally that of a truncated cone, this sleeve serving as a mould, and finally a low melting point alloy of lower hardness and modulus than the steel comprising the wires of the cable is cast onto the folded Wires. After cooling, a compact truncated conical mass is thus obtained, called a bung which has been cast directly into the anchoring sleeve which serves as a mould. In this way the bung when under tension on the one hand does not damage the cable and on the other hand is sufficiently firm not to slip out of the sleeve.

Before this technique can be applied to textile cables, it is necessary to have a casting material which at one and the same time has good adhesion and excellent chemical inertness towards the filaments comprising the cable, "a casting -.and/ or polymerisation temperature which does not cause significant degradation of the filaments, sufficient hardness not to slip out of the sleeve when heavy tension is applied and finally a sufficiently low hardness and modulus not to degrade the filaments when subjected to transverse forces.

To satisfy these requirements, which are in some respects incompatible, synthetic resins are used which polymerise at a low temperature, for example under the action of a catalyst, such for example as epoxy resins.

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However up to the present textile cables fitted with bungs produced by the conventional method of making bungs for steel cables have not been satisfactory, because they cause a strength loss of between 15 and 50% in the area of the bung. (The loss in strength of a cable is given by the difference between the actual strength of the cable and its practical strength as measured with the cable fixed at one of its ends by means of a bung.)

Up to the present bungs produced in practice fit the sleeve tightly, at least at the narrowest point. This arrangement would appear to lead to the optimum fit of the bung (and hence the best retention of the cable through compression) whilst avoiding an elongation stress on the bung. It has now been found that, on the contnary, a bun-g which is free to stretch Within its sleeve can give stronger anchorage than do the earlier techniques.

The arrangement of the invention successfully mitigates the disadvantages of the earlier means. This new arrangement consists externally of a sleeve of a rigid material, for example metal, defining a truncated substantially tapering channel, and internally of a truncated substantially tapering coaxial bung, made of resin, having a common directrix with the channel of the sleeve, into which the end of the cable is fixed by an appropriate method, the arrangement being characterised by the fact that the tangle at the top of the channel of the sleeve is less than the angle at the top of the bung. The difference between the two angles is preferably less than five degrees and is advantageously about one degree.

In practice the internal forms of the sleeve and of the bung will be of very simple shapes, such as truncated cones of circular or elliptical cross-section, truncated pyramids, truncated ovoids, or sand mounds.

The invention is illustrated in the accompanying drawings in which FIGURE 1 is a schematic cross-section of an advantageous embodiment of the invention, in which 1 indicates the sleeve, 2 the resin bung, and 3 the cable consisting of textile filaments 4, whose opened-out ends are fixed into the bung. FIGURES 2 to 5 are schematic cross-sections of alternative embodiments of the invention.

With the device of the invention, the textile material stretches when subjected to a tensile stress, progressively causing the bung to rest against an increasing fraction of the internal surface of the sleeve as the tension increases. In this way, contrary to what takes place with the earlier bungs, there is no sharp discontinuity between the textile material and the resin since the latter can move freely. Thus the tensile stress is absorbed by an increasingly large part of the bung, which eventually is supported, from top to bottom, by the whole of the surface of the sleeve. Furthermore, transverse forces are a maximum at the top of the bung, that is to say where the tensile stress is a minimum, and conversely the compressive stress is low at the narrow end of the bung where the tensile stress is highest. Thus the cable is not weakened, and does not break at the narrow end of the bung.

Finally, the device of the invention makes it possible for the axis of the bung in the sleeve and the axis of tension of the cable to be automatically made to coincide even if the bung has not been strictly cast around the said axis of the cable.

Resins normally used in this field of application, for example epoxy resins and polyesters, may be used for the manufacture of the bung. These resins may with advantage be reinforced by incorporating various materials such as textile fibres, especially glass fibres, whilst the resin is liquid.

The device of the invention is particularly advantageous for anchoring cables made of synthetic textile materials (polyamides, polyesters, polyolefines, etc.) and especially for cables consisting of a core formed by a bundle of elementary filaments which are parallel to one another and are only slightly twisted or not twisted at all, and at least one external cover which is generally plaited, especially the cables whose manufacture is described in our French Patents Nos. 1,327,110, and 1,354,961.

The following examples illustrate the invention. An expert technician could easily introduce modifications, for example by simple substitution of equivalent materials, without going outside the scope of the invention.

Example 1 99 ends of continuous .polyhexamethylene adipamide yarns each of 30,000 deniers/5,00- strands and of 40 turns/metre Z (right hand) twist, a e passed in parallel, in the form of a Web, through a tank containing a selfvulcanising enriched rubber latex. On leaving the tank, the impregnated ends are carired vertically upwards and are then passed through a calibrating die of diameter close to the final diameter of the cable. The drying of the binder is started at the same time.

The combination of ends is again impregnated with fresh binder, and then passes into a p-laiting machine comprising 24- spindles, each fed by one continuous filament end, again of polyhexamethylene adipamide, of gauge 15,000 deniers/900 strands, twist 70 turns/metre (12 ends with S (left-hand) twist and 12 with Z twist.)

The assembly is then passed into a coloured polyvinyl chloride composition, and thereafter into a conical elastic sleeve whose smallest diameter substantially corresponds to the diameter of the finished cable.

The cable continuously passes through a tunnel oven in which the temperature rises progressively from 60 to 180 C., remaining in the oven for about minutes.

The finished cable has a diameter of 26 mm. and weighs approximately 634g./m.

A 2.70 In. sample is cut from this cable, and its two ends are untwisted over a length of about 25 cm. The component ends are opened out into contiguous conical webs under uniform tension. A truncated conical mould is filled with an epoxy resin composition of trade name ARALDITE, consisting of the following parts by weight:

Parts Epoxy resin (CY 248) 100 Catalyst (HY 965 and 966):

Polyarnide 39 Polyarnide and polyamine 1 After polymerisation, each bung has the shape of a truncated cone, 16 cm. high of apical angle about 16.

Each bung is placed in a metal sleeve of apical angle The cable is subjected to a tensile stress by means of a tensometer until it breaks. This takes place at a load of 20.3 metric tons and the cable breaks in the middle of the sample.

Example 2 The same cable as in Example 1 is used but the bungs are produced by the earlier conventional method, opening out and spreading out the ends of the cable in the same Way and casting the same resin composition into a 16 cm. high sleeve having a top angle of 15 and a base diameter of 40 mm. The cable, fixed at its two ends, is broken by means of the same tensometer as before. The break takes place within the hung at a load of 13.4 metric tons. The comparison between Examples 1 and 2 perfectly illustrates the advance achieved by the device of the invention.

Example 3 Example 1 is repeated with only a single change, namely that the core filaments of polyhexamethylene adipamide are replaced by continuous polyethylene terephthalate filaments.

Breakage takes place in the middle of the sample, at 17.8 metric tons.

Example 4 Example 2 is repeated with the same cable as in Example 3. Breakage takes place within the bung at a load of 13.2 metric tons.

I claim:

1. Device for anchoring a textile cable operating under tension, which comprises a core formed by a bundle of substantially parallel elementary filaments and at least one external envelop covering the said core, the device being constituted exteriorly by a rigid sleeve of generally tapering form, and interiorly by a resin bung, also of generally tapering form which has a common ldirectrix with the sleeve and in which is fixed in any appropriate Way the end of the cable, characterised in that the interior apical angle of the sleeve is less than the apical angle of the bung.

2. Anchoring device according to claim 1, in which the difference between the two apical angles is less than 5.

3. Anchoring device according to claim 2, in which the difference is close to 1.

4. Textile element equipped at at least one end with an anchoring device comprising in combination a rigid sleeve Idefining a truncated tapering channel, and contained within it a truncated tapering resin bung in which the end of the cable is so fixed that the free part of the cable emerges from its narrow end, the bung being substantially coaxial and having a common directrix with the channel of the sleeve and the interior apical angle of the sleeve being less than the apical angle of the bung.

5. Textile elements according to claim 4, in which the difference between the two apical angles is less than 5.

6. Textile elements according to claim '5, in which the difference is less than 1.

7. Textile elements according to claim 5, consisting essentially of a synthetic polymer.

8. Anchoring device according to claim 2 in which the interior of the sleeve and the bung have the form of a truncated cone of circular cross-section.

9. Anchoring device according to claim 2 in which the interior of the sleeve and the bung have the form of a truncated cone of eliptical cross-section.

10. Anchoring device according to claim 2 in which the interior of the sleeve and the bung have the form of a truncated pyramid.

11. Anchoring device according to claim 2 in which the interior of the sleeve and the bung have the form of a sand mound.

12. Textile elements according to claim 5 in which the interior of the sleeve and the bung have the form of a truncated cone of circular cross-section.

13. Textile elements according to claim 5 in which the interior of the sleeve and the bung have the form of a truncated cone of eliptical cross-section.

14. Textile elements according to claim 5 in which the interior of the sleeve and the bung have the form of a truncated pynamid.

15. Textile elements according to claim 5 in which the interior and the sleeve of the bung have the form of a sand mound.

References Cited UNITED STATES PATENTS 2,048,292 7/1936 Rau 24-1231 3,263,289 8/1966 Lagarde 24-123.2 3,283,380 11/1966 Gassner 24-l23. 2,

BERNARD A. GELAK, Primary Examiner.

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