US2674215A

US2674215A - Thread bobbin

Info

Publication number: US2674215A
Application number: US280434A
Authority: US
Inventors: Jr Walter E Thompson; Raymond L Hart
Original assignee: Heminway and Bartlett Manufacturing Co
Current assignee: Heminway and Bartlett Manufacturing Co
Priority date: 1952-04-03
Filing date: 1952-04-03
Publication date: 1954-04-06
Anticipated expiration: 1971-04-06

Description

THREAD BOBBIN Filed April 5, 1952 W. E. THOMPSON, JR.. ET AL April 6, 1954 1m! E9221)? Fggmandl. arf

ATTOR s Patented Apr. 6, 1954 UNITED STATES- ATENT OFFICE THREAD BOBBIN Application April 3, 1952, Serial No. 280,434

8; Claims. 1

This invention relates to bobbins formed of continuous filament thread and has for its object the provision of improved bobbins and a method of making them. The bobbins of our. invention are formed of continuous filament thread formed of filament-formingsynthetic, resinshaving. an exterior coating of synthetic resinuous material and are compressed while the coating material is at adhesive consistency in the direc-- nylon, Orlon (polyacrylonitriles), Saran (copolymers of vinylidene and acrylonitrile), Dacron (polyethylene glycol terephthalate), and

Vinyon N (copolymer of vinyl chlorideandac rylom'trile) are relatively denseand smooth and have the property of plastic memory in varying degrees. end-fibers, such as characterize the thread formed. of staple synthetic filaments and naturalfibers, the bobbins formed of continuous filament thread unravel freely and this results in delays in their use. Ifbobbins'formedof these continuous filament threads were compressed, axially, they would springback on release ofithe pressure because of the smoothness, resiliency, andplastic memory of the thread.

It'has been the practice heretofore in making bobbins of such continuous filament threads'to wind the thread on paper acres whichsupport the bobbins internally and thento-attach paper sides to the paper core to support the bobbins on.

the sides. Even withthis expediency, they. are relatively loose and contain muchlesslengthof thread than they would have in a compressed. state. The unravelling annoyance is still present and a cause of. much delay and loss of thread. Moreover, the bobbin shells occupy space that is utilized with thread in the bobbins" of the inven-- tion.

Bobbins having paper shells or metalbobbins for useain sewing machines: have a tendency to:

Because of the, absence-of projecting spin and release thread which causes an entanglement, thus forcing an interruption of stitching. This is particularly noticeable upon stopping and starting of the machine in normal operation.v Bobbins produced by our method decrease in. diameter as the thread is used resulting in. a constant peripheral speed, whereas the conventional bobbins has a progressively increasing peripheral speed. Therefore, the tend-- ency to spin is greatly reduced in the use of bobbins manufactured in accordance with our invention Inaccordance with the method of our invention, we apply to th exterior surfaces of a core strand of continuous filament synthetic threads a thin coating ofa thermoplasticsynthetic resinone material that softens to adhesive consistency atv temperatures above F., and wind the thread, preferably by standard cross-wind'means to form bobbins of relatively low density and considerably larger in axia1 thickness than. required for use in the intended machine. The synthetic resinousmaterial of the coating is not adhesive at normal temperatures: and is more compressible than the core strand. The bobbins are preferably placed over anarbor orpin to retain their internal dimensions and are com-- pressed inthe direction of their axes of rotation while at a temperature at which the resin ous coating issoftened toeifect adhesive bonding under pressure. The bobbins are reduced in. thickness at least 20%, and most advantageously to around 30%, thereby excluding most of; the air, and forcing theadjacent convolutions of thread into a positivebut weak side-to-side adhesive bonding. On coolin and release of pressure, the bobbins sprin back but a small amount and do not unravel with normal handling. It is advantageous to form bobbins having uniformly fiat sides and this is accomplished according to the invention by pressing the bobbins between dies having sloped, e. g., conically shaped surfaces, to compress the bobbins more-near theircenters than near their peripheries because there is a greater tendency, to spring,

back at the center which diminishes progressively in the direction. of their perimeters.

One important characteristic of the bobbins of:

The accompanying drawing illustrates more Or less diagrammatically, in sectional elevation, an arrangement of apparatus suitable for forming proved bobbins of the invention especially intended for use in sewing machines.

The apparatus illustrated in the drawings comprises a frame I in which a plurality of upp die blocks 2 is mounted, a movable central frame 3 on which a plurality of lower die blocks i is mounted, and a movable lower frame on which a plurality of cylindrical pins or arbors 6 is mounted. The frame I is preferably fixed, while the frames 3 and 4 are reciprocable in an upward and downward direction. The frames I, 3 and 5 are preferably heated to a sufliciently elevated temperature that the die blocks 2 and 4 and the arbors 6 are heated by conductivity to the requisite temperature for heating the bobbins.

In a preferred embodiment of the invention, the compression faces of the die blocks 2 and 4 are conically shaped, the angles a varyin from 1 to 5 to the end that the centers of the bobbins are compressed more than the edges.

The method of the invention will now be described with particular reference to nylon continuous filament thread, it being understood that the method may be applied with slight variations that will be apparent to those skilled in the art to the other continuous filament threads herein mentioned.

Nylon thread, twisted or braided, in varying sizes such as may be used in winding bobbins for sewing machines, net-tying machines, and lacemaking machines, is coated with a synthetic resinous material in any suitable manner. The coating is preferably one that becomes thermoplastic to adhesive consistency at temperatures above 140 F. and which is not tacky at ordinary temperatures. United States Letters Patent 2,590,586 of Walter E. Thompson, Jr. and Rollin W. Taylor describes resinous coating materials and methods of application which may be utilized in carrying out a method of the invention. We .prefer to use the thermoplastic coating materials described in the patent.

We shall now describe the invention in the formation of our improved bobbins from a nylon thread made of 210 denier nylon, spun 13 turns right, matched three cord, and twisted 11 turns left.

A first coating is prepared by dissolving part of 66 nylon flake in a solution. consisting of 2 parts of water and 8 parts of ethyl alcohol (all parts by Weight).

A second coating is prepared by forming a solution comprising 110 parts of ethyl alcohol, 2 parts polyvinyl butyral, and A part oleic acid (all parts by weight).

In applying the coatings, the nylon thread is first run through a bath of the first coating, then through a drying chamber as described in connection with Fig. 1 of the said patent. The sec-- ond coating is applied over an emulsion roll at the time of winding the bobbin. The purpose of the second coating is to diminish the strength of the first coating and eliminate jerking in unwinding; For sewing machine bobbins we may eliminate the first coating and just use the second coating by using a higher concentration of resin than in the above coating. While the patent describes the application of coatings containing from 10% to of resin on the basis of the weight of the core, such amounts of coatings are usually applied only when making bobbins for fishnets, and the like. It is to be understood that for thread to be made into sewing machine bobbins we prefer to use considerably thinner coatings.

The coated thread when at a temperature below the softening point of the coating is wound into cross-wound bobbins in any suitable manner. We prefer to wind the bobbins under an appreciable tension. When using a coating of the type just described, the bobbins are preferably placed in a chamber where they are allowed to become conditioned at a relative humidity of 40-44% at a temperature of about F. The absorbed moisture aids in suppressing the plastic memory when the bobbins are heated under pressure and results in better dimensional stability. The term plastic memory is used herein to define that tendency of certain synthetic resinous materials to return to their original state after having been elongated. In the case of nylon thread and other thread having similar plastic memory characteristics, the suppression of plastic memory in the heating during-coating can be undone if the heating during bobbin compression is at temperatures around 250 F. in the absence of moisture. We, accordingly, prefer to heat the bobbins during compression when in a suitably moist condition.

The bobbins may be left under these moisture conditions for around 24 hours. The conditioned bobbins B are placed over the arbors 6 which are elevated to project above the die blocks 4 and then frames 3 and 5 are raised, the arbor 6 entering the central opening of die block 2. A suincient pressure is applied to reduce the thickness of the bobbins at least 20% as measured in the direction of the axis of the arbor which is the axis of rotation of the bobbin. We prefer, however, in forming nylon bobbins to reduce the thickness to from 30% to 35%. The die blocks and arbors are at such temperatures that the nylon bobbins are heated to temperatures of about 260 F. and the pressure is maintained for about 60 seconds. After the compression and heating have been completed, the frame 5 is lowered to pull the arbor out of the top die block and then frame 3 is lowered slightly, at which position it is held for around 10 seconds to allow the bobbins to set. Following this, frames 3 and 5 are lowered to remove the bobbins.

In one preferred operation, we use die blocks in which the angle a is about 2. These die blocks give the bobbin a concave surface when under pressure, as shown by the broken lines, but when the pressure is released, the bobbins expand much more at the centers than at their peripheral edges and assume the dead flat shape shown in full lines.

A typical bobbin formed of nylon thread in the operation above described had an initial thickness in its axial direction of 0.640 in. and after compression and relaxation a thickness measured in the same direction of 0.420 in. which is a reduction in thickness of 35%. Other bobbins similarly formed having an initial thickness of 0.525 in. before compression and 0.360 in. after compression were reduced in thickness 32%.

In forming bobbins of Dacron thread, we prefer to follow the same practice described in connection with the use of nylon. In forming bobbins of Orion, however, we prefer to heat the bobbins to a temperature of around F. and to hold the bobbins while under compression for about 45 seconds.

Bobbins formed of the continuous filament thread herein described are usually wound over ae'zgew &1 the-core of a bobbin shell: which has retaining sides later pressed on to. prevent, unravelling. Even when so protected; the loose thread unwindsfreely and can easily become entangled'i.

Thecore and supporting side; members occupy considerable space, as inthe-shuttle of asewing machine. 'Iheimprovedbobbin of the invention is very dense and can. be shaped to occupy the maximum space in the machine where it is intended to be used. It can be handledwithout unravelling. As anindication of their unraveliling properties, the bobbins of the invention (with the end of thread unsecured) can be thrown against a wall as one would throw a baseball without causing unravelling. Notwithstanding this property, the bobbin can be unwound smoothly and without the necessity for undue tension, as by the tension of a sewing machine feed. Another important characteristic of the bobbins of the invention is their dimensional stability. The importance of dimensional stability is emphasized by the fact that the bobbins can be produced with such close uniformity that they do not vary more than 0.005 in. in thickness. The bobbins do not appreciably change shape. For example, nylon bobbins of the invention may be exposed to atmospheric conditions of high humidity at normal temperatures without changing shape to any appreciable extent. We attribute the characteristics of our improved bobbins to the combination of the coating and the compression. The compression removes substantially all of the air from the bobbin and brings the adjacent convolutions of thread into side-to-side bonding contact. The threads while in the bobbin appear to have some ellipticity whereby there is appreciable side-to-side attachment.

The bobbins of our invention may be of the type that are unwound from the inside or from the outside. Bobbins for use in standard sewing are usually unwound from the outside. Bobbins of the type used for making fishnets can b unwound from the inside or from the outside depending upon the kind of machine used.

In producing bobbins of nylon thread, for example, the thread may be coated with such an amount of resin coating material as to consist of from to 20% of the weight of the coated thread. Such amounts of coating are suitable for forming bobbins for use in making fishnets which are knot retentive, as described in said patent. When the bobbins are to be used in standard sewing machines, satisfactory bobbins can be formed from thread having coatings consisting of from 1% to 10% of the weight of the coated thread.

The aforementioned patent is concerned primarily with water-insoluble coating resins. This invention is not limited to the use of water insoluble coating materials and utilizes water-soluble coating material such as polyvinyl alcohol for thread to be used in sewing machines and lace-making machines.

In the foregoing description, we have emphasized the production of bobbins having fiat sides because such bobbins give improved results in unwinding and contain the maximum amount of thread on the basis of diameter. However, we may use dies that will give the faces a curved or rounded surface.

We claim:

1. A bobbin of the kind described consisting of a continuous-filament thread comprised of a core of synthetic resinous material of a type which normally has substantially plastic mem- Dry and an exterior coating of a thermoplastic resinous material which is more compressible of 'the bobbin, adhering'to one another with sufficient tenacity to prevent unraveling in normal handling but with insuificient tenacity to prevent unwinding when subjected to unwinding tension, the tightly-compacted condition of the thread and the adherence of the convolutions thereof to one another being the result of axial compression of the bobbin While heated to a temperature above the softening point of the resinous material of the threads, the plastic memory of the resinous material from which the thread is formed having been substantially suppressed, whereby the thread of the bobbin has relatively little plastic memory and the bobbin is dimensionally stable, the bobbin having a relatively great length of thread on the basis of its cubic content.

2. A bobbin as defined in claim 1 in which the core of the thread is formed of a synthetic resin from the group consisting of nylon, polyethylene glycol terephthalate, polyacrylonitrile, and copolymers of vinylidene chloride and acrylonitrile.

3. The method of producing a bobbin of continuous filament thread which comprises winding a bobbin of a thread of synthetic resinous material having a surface which softens at temperatures above F., compressing the bobbin in the direction of its axis sufficiently to affect a substantial reduction in thickness of the bobbin axially thereof and sufficiently t force the adjacent convolutions of the thread into tightly compacted relationship axially of the bobbin, subjecting the bobbin, during the compressing operation, to a temperature at least as high as the softening point of the resinous material from which the thread is made, and maintaining the bobbin under pressure while subject to such latter temperature for a length of time sufficient to bring about softening of the surface of the thread and the securing of the convolutions thereof into adhesive contact axially of the bobbin, whereby the bobbin will not unravel under normal handling but will unravel freely under an unwinding tension.

4. The method of producing a bobbin as defined in claim 3 in which the thread is of a synthetic resinous material normally having substantial plastic memory and in which the bobbin is compressed while in a moist condition an is maintained at a sufficiently high temperature while moist for a length of time sufiicient to substantially suppress the plastic memory of the resinous material thereof.

5. The method of producing a bobbin as defined in claim 3 in which the resinou material from which the thread is formed is a synthetic resin selected from the group consisting of nylon, polypolyethylene glycol terephthalate, polyacrylonitrile, and copolymers of vinylidene chloride and acrylonitrile.

6. The method of producing a bobbin as defined in claim 3 in which the bobbin is compressed to efiect a reduction of at least 20% in thickness.

'7. The'method of producing a, bobbin as de- References Cited in the file of this patent fined in claim 3 in which the bobbin is compressed between convexly-shaped dies having a UNITED STATES PATENTS slope of from 1 to 5 to compress the bobbin Numb r Name Date more in the center than at the periphery. 5 675,801 Stiles June 4, 1901 8. The method of producing a bobbin as de- 1,135,470 Tolman Apr. 13, 1915 fined in claim 3 in which the bobbin. after it has 2,001,977 Riddell May 21, 1935 been reduced in thickness to the desired degree, 2,025,920 Webber Dec. 31, 1935 is held under pressure for a. short period to set 2,448,114 Olson et a1. Aug. 31, 1948 the resinous material, th pressure to which the 10 2,488,890 Anderson Nov. 22, 1949 bobbin is subjected i relieved and the bobbin is 2,564,941 Wellman Aug. 21, 1951 permitted to remain before removal for a short while t relax.