US1766776A - Covered elastic strand - Google Patents

Description

June 24, 1930. cl-sHoLM 1,766,776

COVERED ELASTIC STRAND 4 Filed March 22, 1928 2 Sheets-Sheet 1 June 24, 1930. L, B. CHISHOLM COVERED ELASTIC STRAND 2 Sheets-Sheet 2 Filed March 22, 1928 FEE- Patented June 24, 1930 UNITED STATES LESTER B. CHISHOLM, OF STONEHAM, MA

INC, OF CHELSEA, MASSACHUSETTS,

SSACHUBETTS, ASSIGNOB TO EVERLASTIK, A CORPORATION 01 MASSACHUSETTS COVERED ELASTIC STRAND Application filed March 22, 1928. Serial No. 268,770.

This application is a continuation in part of my application filed April 16, 1927, Serial No. 184,341.

The invention relates to an improvement in 5 covered elastic strands useful in the making of elastic fabrics. These covered elastic strands comprise one or more elastic threads forming a core which is covered with one or more windings of inelastic fibrous material such as silk or cotton wrapped around the core. The elastic strands glve elasticity or stretchability to the fabric of which they form a part.

One great difliculty in the use of covered elastic strands in fabrics arises when any of the strands become broken. The operation of sewing often severs or weakens the elastic core of the strand so that when the strand is placed under tension the broken core will creep and the severed ends of the core will draw back into the covering causing unsightly puckers to appear and this effect is aggravated because the core normally lies within the covering under some tension. After the ends of the broken core have thus run or contracted, the core will lie substantially inert and the strand becomes worthless as an elastic medium. Not only this, but the inelastic thread covering with which the clastic core is provided, no longer being supported at the point of the break in the core, will tend to unwind and become loose and unslightly.

Various expedients have been resorted to to 3 obviate this creeping of the elastic core with respect to its covering in case the core is severed or broken. Attempt has been made to obviate the difliculty by running the covering thread through a bath ofcementing material or elastic adhesive such as latex, and applying the thread thus treated to the core. Attempt in this direction, however, has been found futile for the reason that the covering thread is thereby made sticky and-unsightly and requires one or more finishing thread coverings. Even with such secondary covering the result is unsightly, unsatisfactory and useless from a commercial standpoint. The chief difliculty, however, resides in the fact that the coils or convolutions especially those of the inner coverin or the covering next to .the core become bonded together. This acts as an added resistance to the nor- .mal elasticity of the core until such time as repeated stretchings have destroyed the bond between the coils or convolutions and at the same time have incidentally weakened or ruptured the bond between the elastic core and the covering thread, thereby permittlng creeping of the core when severed or broken which is the objective difiiculty sought to be overcome. In other words, the cementing together of the coils or convolutions results ultimately in destroying the bond between the core and its immediate covering and this permits creepin of the core in case of breakage.

It is accor ingly the essential object of the invention to produce a properly durable and attractive covered elastic strand constructed with particular reference to being readily stretchable, with retained normal elasticity,

and proof against creeping of its elastic core.

with respect to its covering should breakage occur even after long continued and repeated stretchings of the strand.

With this object in view, my invention consists in a covered elastic strand characterized by an elastic core, an inelastic thread covermg applied to the core, the core lying tensioned within the covering so that the coils or convolutions of the covering normally abut against each other to limit the contraction of the elastic core, and an adhesive interposed to form a bond between the core and its thread covering but so excluded from between the abutting surfaces of the respective coils or convolutions of the covering thread as to prevent their being bonded together and enabling them to separate or come together riding upon the core as the form of the core becomes changed during the flexing or relaxing of the elastic strand whereby the elastic core is prevented from creeping with respect to the covering and whereby also owing to the absence of the adhesive between the respective abutting coils or convolutions of the covering thread the elastic strand may be readily stretched without rupturing the bond between the elastic core and its thread covering. The invention can perhaps best be seen and strand under understood by reference to the drawings in which- Figure 1 is a face view of one of the complete elastic strands constructed in accordance with the invention, the elastic core belng assumed to be under slight normal tension.

Fig. 2 is a plan corresponding to Fig. 1, but showing the elastic strand under greater tension than its normal tension.

Fig. 3 is a transverse sectional view of the strand when tensioned above its normal tension.

Fig. 4 is substantially the same as Fig. 1 but in which the strand is shown provided with av secondary thread covering lying outside the primary covering which is fixed directly to the core;

Fig. 5 is a face view showing the manner in which the inelastic thread covering is applied to a highly tensioned core, and

Fig. 6 is a side elevation of certain mechanism found useful in the making of the improved strand and to which mechanism special attention will hereinafter be directed.

Referring to the drawings 9- 1 represents the elastic core portion of the elastic strand and this may comprise ,one or more elastic threads. 2 and 3 represent respectively the inelastic thread coverings of the elastic strand, 2 representing the primary or inner covering in direct contact with the elastic core and 3 the secondary or outer covering wrapped around the primary covering. Each of these coverings may consist of one or a group of inelastic threads. 4 is the 'cementing material which bonds the primary covering 2 to the elastic core.

. In carrying out the invention the elastic core to be covered preliminary to the winding of the covering thereon is tensioned or stretched substantially as shown in Fig. 5 to an extent greater than its normal tension or, in other words, the tension under which the core lies in a normal unstretched strand as shown in Fig. 1, it being understood that in an elastic strand the core lies within the some tension. The amount of tension given the core preliminary to the winding of the covering thereon is preferably to a degree just short of its maximum tension or stretch avoiding all possibility of breakage. To the elastic strand thus tensioned a thread covering 2 is applied in the usual manner. This thread covering may consist of a single thread or a number of combined threads. The thread covering is so applied that a space will separate its coils. The amount of space between the coils is commensurate with the amount of stretch desired to be attainedin the completed strand. That is, as the core is allowed to contract the coils will be brought together limiting further contraction of the core which will then be held tensioned within the covering and accordingly the amount of separation of the coils determines the amount of stretch desired to be obtained in the completed strand.

After the application of the thread covering 2 the covered core still tensioned as aforesaid with the coils of the thread covering separated from one another, is passed through a bath of cementing material in order that the cementing material may enter between the coils of the thread covering and form a bond between the thread covering and the elastic core, cementing the one to the other. When applied in this way I have found that the ordinary rubber cements are inade uate inasmuch as they will not proper between the coils of the thread and form such bond between the its covering as will properly cement the core to the covering. I have found, however, that if a water-dispersed rubber or water emulsion of rubber be employed in this connection or one in which the rubber is in a very finely divided form, such preparation of rubber will act effectively and will enter between the coils of the thread covering and penetrate sufficiently to form a proper bond between the elastic core and the covering.

After passing through the bath of cementing material the covered strand is then freed of surplus cement before the strand has been exposed to the air. In connection with this freeing of the strand of surplus cement, it is desirable that the covered strand be freed in so far as possible of all cementing material other than that remaining to form a proper bond between the core and its covering.

After its freeing of surplus cementing material, the covered strand with core still tensioned has applied to it an outer or secondary thread covering 3 as shown in Fig.4 care being taken that before the application of this outer covering the initially covered strand shall not contact with any surface on which cementing material might accumulate and harden, or, in otherwords, any surface from which bits or pieces of the cementing material might be picked ofl" and adhere to the running strand. The outer thread covering is applied in the same manner, with substantially the same spacing of coils as the inner covering, except that the spirals are preferably made to runin a reverse direction. This outer covering is for the purpose of adding finish to the thread and by enveloping the inner covering, bearing more or less cementing material on its outer surface, prevents it from gumming mechanism or rolls over which the strand is led and to which, were it not for the outer enveloping covering, cementing material from the inner covering might adhere and accumulate and be picked off in small bits or pieces from time to time by the running strand, it being a very diflicult matter to eliminate all surplus cementing material from the outer or exposed surface of the initial covercovering core and y enter cement may be employed provided the rubber solvent in the rubber cement is not such as will injure the elastic core. After passing through the bath of cementing material the elastic core is freed of surplus cement before the core has been exposed to the air the same as before and afterward a thread covering is applied to the elastic core which then bears a thin film of cementing material, care being taken that before the application of the thread covering the coated core shall not contact with any surface on which the cementing material might accumulate and harden and bits thereof be afterward picked off by the running core. The thread cover' ing thus applied is applied with coils separated from one another according to the manner of application of the initial thread coverin in the method first described. With the t read covering thus applied to the elastic core as shown in Fig. 1 a secondary or outer thread covering as shown in Fig. 4 is not necessary. It may be applied, however, if desired to give further finish to the strand.

In Fig. 6 is shown certain mechanism which has been found useful in the making of the improved strand. As shown in this mechanism -5 and 6 represent rotary threadcarrying spools. These spools are arranged in vertical alignment one above and spaced from the other, the spool 6 being arranged above the spool 5. It will also be observed that the spool 6 is arranged in an inverted position with relation to the spool 5. Each of the spools is provided with a flier 7 of a type commonly employed in such connection. Located in the space between the two spools is a receptacle 8 containing cementing material. At its bottom this receptacle is provided with a bottom plate 9 having an opening through it and this plate is faced on its inner side with a rubber pad 10 through which the opening in the plate is continued. At its top the receptacle is provided with a cover 11 having a relatively large opening through it and this opening is closed by a rubber pad 12 having an opening through it which opening is in substantial vertical alignment with the opening through the bottom plate andpad at the bottom of the receptacle. The pad-l2 is held in place by a fixed plate 14 through which the opening through i the pad 12 is continued. In the operation of these parts it will be assumed that the elastic core is running under suitable tension through the spindles of the respective spools and through the receptacle and cementing material therein, entering the receptacle by way of the opening atthe bottom through the bottom plate and pad 10 and passing from the receptacle at the top by way of the opening through the pad 12 and its retaining plate.

The thread covering 2 or the thread which forms the initial covering for the elastic core, arranged upon the spool 5, is first wrapped around the running core with the coils of the winding properly spaced from one another substantially as shown in Fig. 5. After the initial winding of the core the covered core passes upwardly through the openlng in the bottom of the receptacle and pad 10 arranged adjacent it, and thence through the bath of cementing material which then becomes applied to the covered core. As the covered core passes upwardly through the" pad 12 and its retaining plate at the top of the receptacle to the atmosphere, the pad 12 will snugly embrace the covered core pass ing through it and acting as a scraper will remove from it all excess cementing material before exposure of the covered core to the atmosphere. After passing from the top of the receptacle the covered core passes d1- rectly to receive the secondary or exterior thread covering 3 which is carried by the spool 5. No opportunity is given for the running core to have contact with any surface to which cementing material thereon may adhere before receiving this secondary thread covering. The secondary thread covering 3 is wound in substantially the same manner as the primary thread covering 2 with proper spaces between the coils, but preferably in reverse direction to the primary winding. After the application of the outer covering the completed strand passes through the spindle of the spool 6 and thence to a suitable takeup mechanism.

Instead of providing the elastic core with an initial thread covering before passing through the bath of cementing material the initial covering may be dispensed with and the elastic core passed directly through the bath of cementing material and afterward receive a thread covering like that provided by the thread from the spool 6 of the mechanism shown, this thread then forming a primary covering. In such case a single thread covering only is necessary but another or secondary covering may be added if desired to give finish just as it is commonly added to ordinary covered elastic strands. For a more detailed description of the method and apparatus used for the purpose of making this improved elastic strand reference is made to ered elastic thread or my copending application, Serial No. 202;- 906, filed July 1. 1927.

Having thus fully described my invention. I claim and desire to secure by Letters Patent of the United States:-

s a new article of manufacture, a covcord comprising an elastic core, a covering-thread wrapped around the said core, so that its reaches normally abut against each other to limit the contraction of the said elastic core, and an adhesive interposed directly between the outer surface of thesaid elastic core and the inner'surface of the said covering-thread, but excluded from between the abutting surfaces of the respective reaches thereof, whereby the elastic core is prevented from creeping with respect to the covering-thread and whereby, owing to the absence of adhesive between the respective abutting reaches of the said covering-thread, the said elastic core or thread may be readily stretched without rupturing the bond between the said core and. coverin LESTER B. CHISHOLM.

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