US3595276A

US3595276A - Method and apparatus for introducing a weft thread into a sheet of warp threads

Info

Publication number: US3595276A
Application number: US792646*A
Authority: US
Inventors: Andrzej Wrzesien
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1969-01-21
Filing date: 1969-01-21
Publication date: 1971-07-27
Anticipated expiration: 1988-07-27

Abstract

This invention concerns a method of introducing at least one weft thread into a sheet of warp threads so as to assist in holding the sheet together, the said method comprising employing at least one toothed wheel which is rolled transversely across the sheet periodically to raise and lower predetermined warp threads in a sequence which permits the passage of the weft thread transversely of at least a part of the sheet, and introducing the said weft thread over and under the said predetermined warp threads.

Description

United States Patent Inventor Andrzej Wrzesien West Didsbury, England Appl. No.- 792,646 Filed, Jan. 21. 1969 Patented July 27, 1971 Assignee Rolls-Royce Limited Derby, Derbyshire, England METHOD AND APPARATUS FOR INTRODUCING A WEFT THREAD INTO A SHEET 0F WARP THREADS [56] References Cited UNITED STATES PATENTS 773,808 11/ 1904 Pentlarge 139/28 2,769,222 1 H1956 Southwell 139/291 3,039,169 6/ 1962 Frickert 139/11 3,147,774 9/1964 Fontaine 139/29 3,283,788 11/1966 Bottomley 139/28 3,426,805 2/ 1969 Shim'well 1 39/ 123 Primary ExaminerHenry S. J audon AttorneyCushman, Darby & Cushman PATENTEUJULZ'IIHYI 3,595,276

sum 3 OF 3 Inventor Amngzar M1 in, I'ZN METHOD AND APPARATus FOR INTRODUCING A WEFT THREAD INTO A SHEET or WARP TnRRAns This invention concerns a method and apparatus for in- 5 troducing a weft thread into a sheet of warp threads so as to assist in holding the sheet together. This may, for example, be desirable if the sheet is to be passed to a subsequent treatment, such as a heat treatment. 1

According to the present invention, there is provided a method of introducing at least one weft thread into a sheet of warp threads so as to assist in holding the sheet together, the said method comprising employing at least one toothed wheel which is rolled transversely across the sheet periodically to raise and lower predetermined warp threads in a sequence which permits the passage of the weft thread transversely of at least a part of the sheet, and introducing the said weft thread over and under the said predetermined warp threads.

Preferably the weft thread is introduced during longitudinal movement of the sheet.

The weft thread is preferably carried by a carrier member which is reciprocated transversely of at least part of the sheet.

The sheet of warp threads may be made up of a plurality of tows of warp threads.

Moreover both the warp and weft threads may be made up of continuous filaments.

A plurality of weft threads, ora plurality of different por tions of the same weft thread, may be introduced into the said sheet, the various weft threads or said portions being longitudinally spaced apart and introduced over and under different warp threads.

The invention also comprises an apparatus for carrying out the said method comprising means for supporting a sheet of warp threads, at least one toothed wheel for periodically raising and lowering predetermined warp threads of said sheet, means for rolling the toothed wheel transversely across the sheet so that the predetermined warp threads are raised and lowered in a sequence which permits the passage of a weft thread transversely of at least a part of the sheet, and means for introducing the said weft thread over and under the said predetermined warp threads.

The means for supporting the sheet may comprise means for moving the warp threads longitudinally during the introduction of weft thread.

The means for introducing the weft thread may comprise at least one carrier member, and means for reciprocating the or each carrier member transversely of at least part of the sheet.

The or each carrier member is preferably a hollow needle through which the weft thread may pass.

Means may be provided for adjusting the width of the said sheet. Thus the last-mentioned means may comprise a comb having teeth whose distances apart may be varied and between which the warp threads may extend.

Means may moreover be provided for improving the uniformity of the sheet in the transverse direction.

There may be means for detecting excess tension in the sheet and/or breakage of a weft thread, and for stopping the machine when such excess tension or breakage is detected.

Means may be provided for heating the sheet after the weft thread or threads has been introduced thereinto.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which:

FIGS. 1 to 3 are diagrammatic perspective views of different parts of an apparatus in accordance with the present invention.

Referring to the drawings, a creel 31 carries a number of bobbins 32 each of which supports a cheese of polyacrylonitrile or other continuous carboniferous filament.

I A tow 33 of the filaments is withdrawn from each of these cheeses and passes through a respective nylon tube 34 and thence to a respective nylon tube 35 in an assembly plate 36. The

tubes

34, 35 serve to separate the various tows 33 from each other to prevent the filaments thereof from becoming en- 75 tangled and damaged, and also to limit external damage to these filaments.

As will be seen from FlG..1, the tows 33 which have passed through the nylon tubes35 of the'assembly plate 36 pass between teeth 37 of a comb 38. The comb 38 functions as a spacing means and is constituted by a lazy tongs member (not shown) which carries the said teeth 37 and which may be adjusted (by means not shown) so as to alter the distances of the teeth 37 from each other. Thus by adjusting the spacing of the teeth 37 a variation may be made to the width and density of the sheet 40 into which the tows 33 are ultimately formed.

Alternatively, the width and density of the sheet 40 may be adjusted by arranging that the nylon tubes 35 can be moved towards and away from each other.

The tows 33 which emerge from the nylon tubes 35 and which pass through the comb 38 are in the form of strands of continuous filament of roughly elliptical cross section. In order, however, to improve the uniformity of the resultant sheet 40 in the transverse direction it is necessary to spread the tows 33 out to form a homogeneous sheet having a thickness of, say 0.005 inch. The tows 33 are therefore passed over a horizontal roller 41 and alternate tows 33 are then passed respectively above and below a horizontal bar 42, the upper tows passing beneath a horizontal bar 43 which is disposed adjacent to the bar 42. The tows which has thus passed to opposite sides of the bar 42 then pass to opposite sides of a stainless steel plate 44 forming part of a spreader unit 45. Laminar phosphor-bronze springs 46, which are disposed on opposite sides of the plate 44, are forced against the latter so as to effect spreading of the respective tows. The arrangement of the two sets of tows is such that the spaces between the tows in the bottom set coincide with the centerlines of the tows in the top set.

All the tows then pass over a plate 50 and beneath an inflated rubber tube 51, the pressure in which is detected by a pressure switch 52 (of known construction) the rubber tube 51 being sandwiched between the plate 50 and a further metal plate (not shown). Thus any excess tension in the sheet 40 (which may be caused, for example, by an entangled tow on a cheese, or by a large knot which causes lodgement of the tow in one of the nylon tubes) will cause the pressure in the rubber tube 51 to rise. When the excess pressure exceeds a predetermined level, a circuit (not shown) in which the pressure switch 52 is arranged will stop the whole apparatus.

The tension generated in the tows 33 by pulling them off their cheeses and passing them through the spreader unit is not sufficiently high and is not sufficiently uniform transversely of the sheet 40 to enable the sheet to be held together by subsequently introduced weft threads. The sheet 40 is therefore passed between a pair of intake drafting rollers 53, under a horizontal bar 54, over

horizontal bars

55, 56 and between a pair of outlet drafting rollers 57. The rollers 53, 57 rotate at the same angular velocity. However, the rollers 57 are of somewhat larger diameter than the rollers 53 and there is therefore a small circumferential speed differential between the rollers 53, 57 such that the sheet 40 will be drafted by approximately 5 percent.

This amount of draft may be modified, if desired, by making one of the pair of rollers 53 a worm roller having a square worm thread thereon. Thus by altering the width of the square worm thread thereon, it may be arranged that from to 75 percent of the filaments in the sheet 40 will be gripped between the rollers 53, the remaining 50 to 25 percent thereof being permitted to slip progressively between the rollers 53.

The rollers 53, 57 may be driven at a speed such as to move the sheet 40 continuously at a speed of about 1 to 2 yards per minute.

A bar 60 extends transversely across the sheet 40 and above the latter, and supports two carriages 61 which are slidable thereover. Each of the carriages 61 is connected to a rod 62 of a pneumatic or hydraulic double acting ram 63 which may thus be used to effect reciprocation of the respective carriage 61 transversely of the sheet 40. (In order to simplify FIG. 1, only one of the rams 63 and rods 62 is shown in its entirety).

Instead of providing rams 63 other prime movers such as lever and cam systems and linear induction motors may be used.

Each of the carriages 61 supports a freely rotatable toothed wheel 64 and a hollow needle 65, which extends to a position adjacent the bottom of the toothed wheel 64. The needles 65 may be made of stainless steel thick wall tubing and may be gradually tapered along their lengths. The teeth of the toothed wheels 64 are formed by providing a plurality of angularly spaced-apart slots 66 which extend to the periphery of the wheel and throughout the axial length thereof. The width of each of these slots is such as to permit the entry thereinto of a portion of a tow.

The slots 66 in the toothed wheels 64 may be relatively narrow compared with the width of the unslotted parts around the circumference of the toothed wheels 64 which alternate with between them.

A weft thread 70 is introduced through each of the needles 65 so as to emerge adjacent to the bottom of the respective toothed wheel 64.

Thus as each carriage 61 is reciprocated across the respective part of the sheet 40, the wheel 64 engages the warp threads of the sheet 40 so as to be rotated thereby and serves periodically to lower predetermined warp threads in a sequence which permits the passage of the weft thread 70 so that the latter passes over the said predetermined warp threads and under all remaining warp threads.

As will be seen from FIG. 1, the arrangement is such that each of the toothed wheels 64 is moved between a position in which it is disposed beyond the sheet 40 to a position in which it has moved past the centerline of the sheet. Thus, when the parts are in the position shown in FIG. 1, the portion of the weft thread 70 which has been introduced by the right-hand needle 65 will be trapped between the various tensioned warp threads of the sheet and, due to the longitudinal movement of the latter, will have been carried away from the respective toothed wheel 64. At the same time, the left-hand needle 65 will have been introduced to its maximum extent into the sheet 40 and, as it is withdrawn, it will leave the weft thread behind it embedded in the sheet 40. Thus in the construction shown in the drawings, two weft threads are employed, each of which extends from its respective side of the sheet 40 to a position beyond the longitudinal centerline of the sheet. There thus may be an overlap of, say 3 inches between these two weft threads at the center of the sheet 40.

When spun yarn is used for the weft thread 70, it is not necessary to have any mechanism to retain the weft thread 70 in the sheet. However, for continuous filament yarn, a hook system (not shown) can be used to prevent the weft thread from being pulled out of the sheet during the withdrawal of the needles.

Since the wheels 64 will be frictionally rotated by engagement with the sheet 40, they will continue to rotate even when moved to a position free of the latter. Indeed, means may be provided deliberately to rotate them. As a consequence, the angular positions of the slots 66 in a wheel 64, will, with respect to the sheet 40, vary every time the respective carriage 61 is reciprocated. As a consequence, and as shown in FIG. 1, different portions 71, 72 of the same weft thread 70 which are longitudinally spaced apart will be introduced over and under different warp threads so as to produce a substantially random weave.

To prevent unnecessary rubbing, means (not shown) may be provided so as to lift each of the wheels 64 out of contact with the sheet 40 whenever the respective needle 65 is withdrawn therefrom. Thus a pneumatic ram may be used for this purpose.

Each of the weft threads 70 is withdrawn from a cheese 73 and, on its way to its respective needle 65, passes a weft break detector 74. The detectors 74 may be photoelectric, capacitive, electromechanical, or incorporating fluid logic devices, and are such that in the event of weft breakage, a signal is provided which stops the apparatus.

After the sheet 40, which has had the weft threads 70 so introduced, has passed between the rollers 57, it passes between two plates 75 of a heating unit 76. The heating unit 76 and means for moving it may be of known constructions, as shown for example in US. Pat. No. 2,769,222. Each of the plates 75 may, for example, be constituted by a steel plate coated with polytetrafluorethylene. Each of the plates 75 carries an infrared heater 77, the temperature of which is maintained reasonably constant by a thermostat (not shown). The sheet 40 is thus heated while under tension so that its material will stretch, and protruding filaments will be shrunk, and its modulus of elasticity will be increased. Thus a sheet of material will be produced which is more highly orientated so as to facilitate its consequent handling.

Whenever the machine stops, the plates 75 and their heaters 77 are moved away from the sheet 40 (by means not shown), but the heaters 77 are not switched off.

If desired, high frequency dielectric heating can be used instead.

In order to produce a stable beam of the sheet 40 which has been so heated, it is necessary to introduce at intervals, narrow strips of paper 78 called collars at the edges of the beams. This operation is usually performed by hand. Semiautomatic means are illustrated at 80 (FIG. 3) to allow quicker and easier insertion of the collars 78. The system can, if desired, be fully automated to deal either with the continuous length of collar 78 or to cut and insert short lengths as required.

The sheet 40 is thus wound onto a spool 81 which is rotated by means of an electric motor 82 by way of a reduction gear 83 and hydraulic dashpots 84. The surface velocity of the spool 81 is considerably higher than the velocity of the sheet 40 which has just been heat treated, and tension is thus generated in the latter due to slip in the hydraulic dashpots 84 that act as couplings. The tension in the sheet can be adjusted by changing the torque settings of the hydraulic dashpots 84 or by changing the speed ratio between the sheet 40 and the circumferential velocity of the spool 81.

Torque electric motors can be used instead of hydraulic dashpots. In this case, torque values are changed by altering the voltages supplied in the motors.

In either case, a condition of constant tension can be achieved and the level of tension can be preset. The spools 81 may be wound to a diameter of 24 inches, but larger diameters can also be used ifdesired.

As will be appreciated, although the invention has been discussed above in relation to the production of a sheet of polyacrylonitrile tows, the invention may also be used to provide fabrics of novel construction from, say, natural fibers.

Iclaim:

1. A method of introducing at least one weft thread into a sheet of warp threads so as to assist in holding the sheet together, said method comprising moving the sheet of warp threads longitudinally in a substantially flat plane, employing at least one freely rotatable toothed wheel which is reciprocated transversely across the sheet and in engagement with the warp threads to effect rotation of the toothed wheel to periodically depress predetermined warp threads out of said flat plane, while leaving remaining warp threads in said flat plane, in a sequence which permits the passage of the weft thread transversely of at least a part of the sheet, and introducing the said weft thread between said predetermined warp threads and said remaining warp threads, and moving the toothed wheel so that, at the end of each complete reciprocation thereof, the toothed wheel is disposed beyond the sheet and out of engagement with the warp threads.

2. A method as claimed in claim 1 in which two weft threads and two toothed wheels are employed, each weft thread and toothed wheel being carried by a carriage which is reciprocated transversely of a part only of the sheet, the carriages being moved to opposite sides of the sheet.

3. A method as claimed in claim 1 in which the sheet of warp threads is made up of a plurality of tows of warp threads.

4. A method as claimed in claim 1 in which the warp and weft threads are made up of continuous filaments.

5. Apparatus for introducing at least one weft thread into a sheet of warp threads so as to assist in holding the sheet together, said apparatus comprising means for moving a sheet of warp threads longitudinally, at least one freely rotatable toothed wheel engageable with the warp threads for periodically depressing predetermined warp threads of said sheet, means for reciprocating the toothed wheel transversely across the sheet and in engagement with the warp threads to effect rotation of the toothed wheel so that the predetermined warp threads are lowered in a sequence which permits the passage of a weft thread transversely of at least a part of the sheet, and means for introducing the said weft thread over the said predetermined warp threads and under the remaining warp threads, the toothed wheel, at the end of each complete reciprocation thereof, being disposed beyond the sheet, and out of engagement with the warp threads.

6. Apparatus as claimed in claim 5 in which two weft threads and two toothed wheels are employed, the means for introducing each weft thread comprising a carriage which carries both a carrier member for the weft thread and a toothed wheel, and means for reciprocating each carriage transversely of a part only of the sheet, said carriages being positioned for movement to opposite sides of the sheet.

7. Apparatus as claimed in claim 6 in which the carrier member is a hollow needle through which the weft thread may pass.

8. Apparatus as claimed in claim 5 in which means are provided for improving the uniformity of the sheet in the transverse direction.

9. Apparatus as claimed in claim 5 in which there are means for detecting excess tension in the sheet and for stopping the apparatus when such excess tension is detected.

10. Apparatus as claimed in claim 5 in which there are means for detecting breakage of a weft thread, and for stopping the apparatus when such breakage is detected.

11. Apparatus as claimed in claim 5 in which means are provided for heating the sheetafter the weft thread has been introduced thereinto.

Claims

11. Apparatus as claimed in claim 5 in which means are provided for heating the sheet after the weft thread has been introduced thereinto.