US2271057A

US2271057A - Retractile conductor cord and method of making such a cord

Info

Publication number: US2271057A
Application number: US273174A
Authority: US
Inventors: William T Barrans
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1939-05-12
Filing date: 1939-05-12
Publication date: 1942-01-27
Anticipated expiration: 1959-01-27
Also published as: GB536937A

Description

Jan. 27, 1942. w. T. BARRANS 2,271,057

RETRACTILE CONDUCTOR CORD AND METHOD OF MAKING SUCH A CORD Filed May 12, 1939 FIG. FIG. 2

INVENTO/P w T. BA RRA NS ATTOR EV Patented Jan. 27, 1942 RETRACTILE CONDUCTOR CORD AND METHOD OF MAKING SUCH A CORD William T. Barrans, Towson, Md., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application May 12, 1939, Serial No. 273,174

3 Claims.

This invention relates to a retractile conductor cord and method of making such a cord, and more particularly to a retractile cord of helically coiled form and method of making such a cord.

, In the telephone and other arts it is frequently desirable to connect electrically operated devices by a compact cord whose length may be extended by a slight tension and returned to a compact form when the tension is released.

Objects of the invention are to provide an effective and efl'icient retractile cord and a method of making such a cord.

In accordance with one embodiment of the invention, a plurality of conductors are encased in a rubber sheath and vulcanized into a helical coil, after which the convolutions of the coil are inverted or reversed to increase the retractility 01' the coil.

A' complete understanding of the invention may be had by reference to the following description, taken in conjunction with the accompanying drawing, in which Fig. 1 is a detail view of a retractile cord with a rubber sheath in the form in which it appears immediately after vulcanization of the sheath; and

Fig. 2 is a similar view of the same cord after the convolutions have been reversed.

Referring now more in detail to the drawing, a retractile cord is shown having one or more conductors 5 which are encased in a sheath i of rubber or other suitable material. The rubber sheath 6 may be extruded upon the conductors in any well-known manner, after which the sheathed conductor is wound upon a mandrel in helical form. It is to be understood that the term helical is used in its broadest sense and will represent a coil or spiral produced when a strand is wrapped about amandrel the transverse cross section of which may be triangular, square, rectangular, circular, oval or a modification of any of these. The rubber sheath of the cord is then vulcanized on the mandrel. When a cord thus made is suspended from one end the convolutions tend to separate due to the weight of the cord. indicating that the initial retractility is not very high. The tendency for the coil to retract into closely coiled convolutions can be greatly increased by reversing 'the convolutions. The greater the spacing between convolutions within reasonable limits the greater will be the retractility of the cord. This inverting of the convolutions may be accomplished by beginning at one end and inverting each convolution separately. However, a more eflective way of reversing the convolutions is by taking a rod 1 in the form of an enlarged needle having an eyelet 8 at one end, projecting it through the coil, and inserting the ends of the conductors 5 through the eyelet. Then by drawing the needle through the coil all or the convolutions or the coil may be inverted from right-hand convolutions, as shown in Fig. 1, to left-hand oonvolutions, as shown in Fig. 2. If it be desired that the final form of the coil have right-hand convolutions, the coil is originally made with left-hand convolutions and then inverted. By this means 1. A method oi! making a retractile cord which comprises extruding a continuous unvulcanized rubber sheath on a flexible conducting core, forming the resulting product into helical form. vulcanizing the sheath on the core to form a retractile cord and inverting the helix to increase the retractility of the cord by drawing one end of the cord through the helix.

2. A method of making a retractile cord which comprises applying a continuous unvulcanized rubber sheath directly on a flexible conducting core, thereafter forming the resulting product into helical form, vulcanizing'the sheath on the core to form a retractile cord and inverting the helix to increase the retractility oi' the cord by drawing one end 01 the cord through the helix.

3. A method of making a retractile cord which comprises coating a conductor with thermoreactive material, forming the coated cord into retractile form, setting said thermoreactive material in the form 01' a helix, and drawing one end 01' the cord through the helix to invert the cord.

WILLIAM T. BARRANS.