US2452434A - Apparatus for making elastic coil structures with longitudinal ends - Google Patents

Description

0ct. 26, 1948. w. J. CREHAN ET AL.

APPARATUS FOR MAKING EL'ASTIC COIL STRUCTURES WITH LONGITUDINAL ENDS Filed May 7, 1945 Patented Oct. 26, 1948 UNITED STATES rrlbcs APPARATUS FOR MAKING ELASTI'C 1CIL STRUCTURES WITH LONGITUDINAL ENDS Company, Chicago,

nois, and Ralph D. Collins, Beverly Ill., a corporation of Elli- Hills, Calif.

Application May 7, 1945, Serial No. 592,398

Claims. 1

This invention relates to improvements in apparatus for making elastic coil structures with longitudinal ends.

t is now well known that retractile and extensible extension cords or cables, for various purposes, principally electrical, may be satisfactorily constructed by providing a conductor or a plurality of conductors with a covering or sheath of incompletely vulcanized rubber or the like, then closely coiling it into the form of a heliX, and then vulcanizing it, after which the cable will be readily extensible, as for example, for extension cord purposes, without damage thereto while being automatically retracted by its own resilience to closely coiled helical formation when released, and that the resilience of the cable may be enhanced by reversing the direction of the coils as broadly disclosed and claimed in the Campbell Patent No. 2,173,096.

In the application of Ralph D. Collins, Serial No. 588,043, filed April 12, 1945, there is shown and broadly claimed a method and means of forming such elastic coil cables with longitudinal ends, and the present invention aims to provide improved method and means for making .cables of this class, with enhanced simplicity and improved results.

The invention will be readily understood by reference to the following description, taken together with the accompanying drawings, showing an illustrative embodiment of the invention, and in which drawings- Figure l is a view, partly in section, of the improved expedients of the present disclosure and being in part a section taken on the line l-I of Figure 2;

Figure 2 is a section taken on the line 2--2 of Figure l; n

Figure 3 is a section taken on the line 3-3 of Figure 1 looking in the opposite direction; and

Figure 4 is a view showing the cable after being reversed.

Referring in general to the drawings, it will be understood that the cable Hl includes a coiled portion and an uncoiled portion which is adapted to serve as a connecting tail for the cable, and in this instance, there are formed two such connecting tails, one at each end of the cable. The intermediate coiled portion of the cable is here given the numeral l l with an uncoiled portion l2 at one end and I3 at the other end. The mandrel i4 is provided upon which is wound, before vulcanizing and in the form of a helix, the coiled portion Il. The cable Il) may comprise one or more conductors l5 encased in a sheath I6 of vulcanizable material, such as one of the syn'- thetic elastomers or rubber-like substitutes Which are now on the market, one known as Buna-S having been used and found suitable.

In accordance with the present invention, means are provided for holding one or both longitudinal ends l2, I3 longitudinal of the coil, while the material i6 of the cable is being vulcanized, said means comprising a sleeve member I1 formed of a soft rubber-like material which is not substantially hardened by the vulcanization treatment of the cable, later more particularly referred to, and which remains substantially softer than the vulcanizable rubber-like material of the cable to avoid marking of the cable, particularly at the point i8 where the bend occurs between the coiled and uncoiled portions.

The sleeve member Il is preferably formed of a synthetic material known as I-Iycar and which is comprised of a copolymer of butadiene and acrylonitrile having the required ingredients to give it, when molded under heat and pressure to the form here shown, a Shore durometer hardness reading of the order of between 20 and 30 and so as to withstand a temperature of say 250 Fahrenheit for the period of time, say, an hour or so, during which the cable ID is being sub-l jected to the vulcanizing temperature, without being substantially hardened and while remaining substantially softer than the vulcanizable material lli of the cable.

A suitable formula for the composition of the sleeve member li, as at present advised, is thought to be as follows: f

Parts by weight Hycar OR l5 100 Carbon black 50 Plasticizer 30 Anti-oxidant 3 Accelerator 1 a composition for the sleeve member l1 whicheontains elemental sulphur, so that no substantial subsequent vulcanization or setting of the material of the sleeve occurs after its initial for" mation in the soit state here described, such setting as occurs during its initial formation desirably exhausting th'e active cross-linking action of the molecule chains under the influence of the accelerator, say, and thus leaving the sleeve member permanently soft, but elastic.

As here shown, the sleeve member Il is split throughout its length as at I9 so that it may be readily slipped over the mandrel Ill. A reduced portion 28 of the sleeve snugly encircles the mandrel at th'e outer end of the sleeve'. At its inner end, the sleeve isenlarged as at 2l to form a cup-like portion which receives and telescopes over the adjacent coils 22 of the cable I il. Upon the outer periphery of the enlarged portion 2i of the sleeve is a longitudinally extending groove 23 in which the longitudinal end I 2 or I3 as the case may be, is received and laid, A perforation or passageway 2t from the interior of the enlarged portion 2l of the sleeve to the groove 23 passes the cable end therethrough. The edge of this opening 2li, as at 25, is rounded or beveled so as to further safeguard against marking the cable, particularly at this I8 in the cable occurs.

At the place where the sleeve member il is split longitudinally, as at i9, the sleeve may be laterally extended on each side of the split to form a pair of lips 26 by which the sleeve member may be clamped together, after having been locked in position on the mandrel and coiled cable, the clamp 21 being suitable for this purpose.

place where the bend As an alternative, and as shown at the right-hand Y end of Figure 1, the clamp 21 may be applied about the'reduced portion 2i! oi the sleeve member Il, as is also shown in section in Figure 3. The clamp here shown is in the form of a pair of interlocking spring lingers 23 and 253 secured together at their base as by screw 30. One of these spring lingers, such as 28, passes through a slot 3l in the other iinger 2S so as to cross at their free ends 34, and a compression coil spring 32 within the bight portions 33 of the clamp 2l forces the ngers apart at the bight and the free spring ends 34 of the fingers together. These spring ends may be toothed as at 35 to grip the sleeve member Il'.

It will now be understood that, as here shown,

.there are two of the sleeve members il, one at each end of the cable, the sleeve members being identical but reversed in direction so that the two reduced portions 2G extend in opposite directions axially and the two split portions I9 extend in opposite directions laterally. Thus the cup portions 2 I, which' telescope over the cable coils 22, extend in the opposite direction but toward each other.

Further in accordance with the present invention, the uncoiled longitudinally extending portions I2 and I3, which lap the coiled portion I! of the cable and extend toward each other, may be held in position in th'e grooves 23 respectively by being connected together as here shown by a resilient member 35 such as comprising a relatively light coil spring 36a attached at its ends to clamps 3l and Sla, which may be similar to the clamp 2l, which grip the ends of the cable portions I2 and I 3. The coil spring 33 accommodates any changes in length of these cable ends which may occur during the vulcanization treatment. When only one longitudinal end is desired, say the end I2, the resilient member liti may be extended and the clamp 37a secured to the mandrel I4 at 31h.

It is to be understood that when the sleeve member I'I at the left-hand end of Figure l was lirst placed on the mandrel and cable, the cable end I2 was threaded through the passageway 24 of the sleeve member and then the cable was Lic wound on the mandrel to. at least the extent of a few coils such as 22 whereupon the sleeve member il' at the left-hand end of Figure 1 was placed about the coils and clamped together as by the clamp 2l. Then the remainder of the cable was coiled. Then the cable end I3 was threaded through the passageway 24 in the sleeve member Il at the right-hand end of Figure l. Then this latter sleeve member was placed about the mandrel and coil and clamped as shown as by another of the clamps 27. Then the two ends of th'e cable ends I2 and i3 were connected together by the resilient connection 36, the ends then lying in the grooves 23.

The cable while on the mandrel :as shown in Figure l may now be subjected to a vulcanization treatment of any suitable character, such for example, as by being placed in an oven having a temperature of say 250 Fahrenheit or thereabouts, by which treatment the vulcanizable rubber-like material I6 of the cable Iii is cured and given a. permanent set which makes the cable resilient and elastic. During this treatment the sleeve members Il do not substantially change in character, the material thereof as already described being such as not to be affected by this heat treatment,l and they thus remain soft and pliable so as not to mark the cable, as already mentioned.

The vulcanizing treatment having been completed and the sleeve members Il still remaining soft and pliable as already mentioned, the clamps (il are released and the resilient element 36 dis connected from the cable. Thereupon the sleeve members Il are removed and the cable removed from the mandrel. Finally the cord may be reversed or inverted in direction of pitch as already alluded to so as to change the direction of the turns oi the coils from a right-hand screw-thread, so to speak, as in Figure l, to the similitude on a left-hand screw-thread as shown Iin Figure 4, thereby enhancing the resilience of the 'cord as a whole and increasing its retractibility, and causing ends I 2, I3 to extend outwardly.

When the clamp 2 is applied to the sleeve as at the right-hand end of Figure 1 and in Figure 3 it also advantageously keeps the sleeve from relativeA rotation with respect to the mandrel.

It is to be understood that the term cable as here used includes tubular or solid cable-like structures, with or Without conductor wires.

Such changes may be made as fall within the scope of the appended claims without departing from the invention.

The invention having been described, what is here claimed is:

l. Means for making elastic coil structures of the class described embodying a vulcanizable material, comprising a mandrel for coiling a cable thereon in the form of a helix when the said material is incompletely vulcanized, sleeve means extending longitudinally of said mandrel at each end of the cable for supporting during vulcanization an uncoiled portion of said cable extending longitudinally of and lappingsaid helix during vulcanization of the cable material to form an uncoiled connecting tail therefor at each end thereof, and means for connecting said uncoiled portions together to hold them longitudinal of and lapping the cable helix during vulcanization.

2. The structure of claim l wherein the sleeve means comprises a member of soft rubber-like material which is not substantially hardened by the vulcanization treatment of the cable and which remains substantially softer than the materal of the cable to avoid marking of the cable.

3. The structure of claim 1 wherein the sleeve means comprises a member of soft rubber-like material which is not substantially hardened by the vulcanization treatment of the cable and which remains substantially softer during vul-` canization of the cable than the rubber-like material of the cable to avoid marking the cable, said soft rubber-like material having a Shore durometer hardness reading of between 20 and 30.

4. Means for making elastic coil structures with longitudinal ends comprising, a pre-formed longitudinally split sleeve member of soft rubberlike material longitudinally grooved on its periphery for placing about a coiled portion of said structure and having a perforation therein at one end of the groove communicating between the interior of the sleeve and said groove for passing an uncoiled portion of said structure into said groove, an integral reduced sleeve extension portion adjacent said end of said member for placing about a mandrel upon which said coiled portion is coiled, and integral adjacent lips on the member spaced peripherally thereon from said groove whereby the sleeve member may be clamped about said coiled portion and said mandrel.

5. The method of making elastic coil structures V.oanization to hold them longitudinal and lapping the coil, vulcanizing the material while maintaining the said coiled and uncoiled portions in said forms, and inverting the direction of pitch of the coils whereby the uncoiled portions extend longitudinally beyond the coil after reversal and serve as connecting tails for the cable.

WILLIAM J. CREHAN. RALPH J. ARNOLD.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Date Number Name 458,115 Thomson Aug. 18, 1891 2,323,286 Ward June 29, 1943 2,339,683 Cox Jan. 18, 1944

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