CA1095346A - Method and apparatus for manufacturing a three- dimensioned crimp filament - Google Patents

Abstract

METHOD AND APPARATUS FOR MANUFACTURING
A THREE-DIMENSIONED CRIMP FILAMENT

ABSTRACT OF THE DISCLOSURE

A three-dimensioned crimp filament is prepared by twisting a bundle of large denier filaments into a single twist while said filaments are stretched between a freely-rotatable first roller with a peripheral groove having 10-500 mm of diameter at a grooved portion and at least one other freely-rotatable second roller in a total denier of 50,000 - 3,000,000 denier by means of twisting action in a subsequent double twist step, double twisting said single-twisted filaments into a double twist up to said first roller and heating the filaments thus twisted into a double twist while passing them through a tubular guide means, cooling said double-twisted filaments to effect a heat-set while maintaining the twisting action; untwisting said double-twisted filaments thus heat-set to form three-dimensioned crimp filaments, and cutting said untwisted three-dimensioned crimp filaments into staple lengths. The diameter of the first roller at the grooved portion is correlated with the diameter of the double-twisted filaments formed to prevent the spread of the double twist back beyond the first roller, and the width of the peripheral groove and the diameter of the tubular guide means are sufficient freely to receive the double-twisted filament but insufficient to allow it to curl into a greater multiple twist.

Description

3~6 FIELD OF INVENTION AND PRIOR ART
This invention relates to a method and an apparatus for manufacturing three-dimensioned crimp filament and, more particularly, to a method and an apparat:us for manufac-turing three-dimensioned crimp filament of a synthetic fiber used as raw material for locked cushioning material.
Hitherto, filaments have usually been in the two-dimensioned form, and no substantial increase of the resiliency or improvement of the cushioning property has been obtained even if intersections of filaments are locked with an adhesive.
In addition, if it is intended to form three-dimensioned crimps, it is likely that the crimp is chiefly formed only about a portion as a core so that desired three-dimensioned crimp effect cannot be obtained. Further, with the conventional crimp form-ing apparatus where temporary curing is made, the total denieris limited to ~,000 denier at the most in view o~ the mechanism, so that only small crimps can be obtained.
In order to improve the above various drawbacks in the conventional apparatus there has been proposed an apparatus ~0 for continuously manufacturing thick synthetic fiber crimped staples of several hundred denier as a single yarn for cushion~
ing, which is provided with a heating means for effecting wet heating immediately before processing and a temporary twisting heating means for effecting two continuous twists on rope con-sisting of an ordinary primary single twist and a secondarydouble twist~ and in which thermoplastic filaments are given double helical crimps which are thermally set by strong heat-ing means provided between the aEore~mentioned means and then subje`cted to releasing of the temporary twists and then cut-ting by a cutting means (Japanese Utility Model Publication ~ ' ii3~6 No. 40402/74). This apparatus, however, has a drawback in that i-t is difficult to prevent spread o:E the double tw.ist formed in the secondary double twist step back into the primary single twist step or zone.
Such drawbacks in the prior art, are avoi.ded in an apparatu~s comprisi.ng a drive means for pulling filarnents, a group of guide rollers positioning in a reverse U-shaped, said roller group being provided ahead of said drive means and adapted to be rotated so as to give forward and rear-ward portions of a plurality of filaments which stretched with a single twist formed thereon and being transferred by said drive means, mutually opposite twisting actions, a pair of rotative rollers each provided with a yroove~ said roller pair being provided immediately after the roller at the forward end in said roller group and provided with a non-slip means for pulling the single twisted forward portion said filaments at a transfer speed such that the filaments of said forward portion formed into a double twist and are cooled sufficiently to effect a thermal set, a heating means provided ahead of said roller group and serving to heat the filaments formed with a double twist, a single twist transfer roller group provided ahead of said heatiny means and consisting of a plurality of rollers for giving the filaments and given a predetermined rotational tension for guiding filaments formed with a single twist, and a means for stopping spread of double twist, said stopping means being provided on the last roller in said roller group. However, when a pulling roller is used a means for stoppiny spread of the double twist, high compression force presses the formed double twist of the filament, so there are some drawbacks -3- . :

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that not only lmtwis-ting and opening the filament becomes difficult on acco~mt of heat deformation but also -the fila-ment deforms by plas-tic deformation to decrease the cushion-ing property and mechanical strength -thereo.

OBJE:CTS OF THE I~VENTION
__ _ An object of an aspect of the present invention, accordingly, is to provide a method and an apparatus for manufacturing three-dimensioned crimp, which is capable of giving fiber filament crimps having three-dimensioned directivity, that is, three-dimensioned crimp, greatly con-tributing to the increase of resiliency and improvement of cushioning property when the filaments are made as lock material or contained within a cushioning material.
An object of an aspect of the present inven-tion is to provide a method and an apparatus for three-dimensioned crimp filament, which can eliminate spreading the double twist formed in the double twist step back into the single twist step or zone.
_IEF DESCRIPTION OF INVENTION
In accordance with one aspect of this invention there is provided a method for manufacturing a three-dimel~ioned crimp filament comprising: twisting a bundle of large denier filament into a single twist while said filaments are stretch-ed between a freely rotatable first roller with a peripheral groove having 10~500 mm of diameter at a grooved portion and at least one other freely-rotatable second roller in a total denier of 50,000 - 3,000~000 denier by means of twisting action in a subsequent double twist step; double twisting said single-twisted filaments into a double twist up to said first roller ànd heating the filaments thus t~Yisted into a -3a-~;

~g53~6 double twist while passiny them thro~lgh a tubular guide means;
cooling said doubIe-twisted filaments to effect a heat-set while maintaining the twisting action; untwisting said double-twisted filaments thus heat-set to form three-dimensioned crimp filanlents; and cu-tting said untwisted -three-dimensioned crimp filaments into staple lengths, the diameter of said first roller at the grooved portion being correlated with -the diameter of the double-twisted filaments formed from the ~J 0,000-3,000,000 denier bundle to prevent the spread of the double twist back beyond said first roller und~r the -tension necessary to form and mainta.in said double twist, and the width of said peripheral groove and the diameter of said tubular guide means being sufficient to freely receive the double-twisted filament, but insufficient to allow it to curl into a greater multiple twist.
In accordance with another aspect of this inven-tion there is provided an apparatus for manufacturing a three-dimensioned crimp filament comprising: a single-twist roller group comprising a freely-rotatable, first transverse roller with a peripheral groove having 10-500 mm diameter at the yroove portion and at least one other rot.atable second transverse roller; drive means for pulling a bundle of filaments around said transverse rollers and up over and in said peripheral groove in a longitud.inal pathway leading from such peripheral groove to said drive means; twisting means loca~ed ahead of said drive means adapted to give the portions o said bundle of filaments fo~ard and rearward of said twisting means, while stretched along said longi--3b-``: J

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i3~i tudinal pathway and around said transverse rollers and pulled along by said drive means mutually opposite twist-ing actions, whereby the portion of the forward portion ahead of said peripheral groove is given a single twist, the -.
s portion thereof between said peripheral groove and said twisting means, a double twist, and the rearward portion from said twisting means to said drive rneans is untwisted;
tubular guide means provided ahead of said twisting means for the filaments formed with a double twist; heating means serving to heat the said double-twisted filaments to a temperature such that, on cooling, the crimp in said fila~
ments is given a permanent heat-set, whereby untwisting results in a three-dimensional crimp filament; and, cutting ~: :
means for cutting the three-dimensioned crimp filament into 15 5taple lengths while under tension, the diameter of said ; -first roller at the grooved portion being correlated with the diameter of the double-twisted filaments formed said bundle to prevent the spread of the double twist back beyond said first roller under the tension necessary to form and maintain said double twist, and the width of said peripheral groove and the diameter of said tubular guide means being sufficient to freely receive the double-twisted filament, but insufficient to allow it to curl into a greater multiple ~ :
twist.
The filaments used in accordance with the inven-tion may be such synthetic fiber as polyester, polyamide, polyacrylonitrile, polypropylene, polyvinylidene chloride, vinylon and so forth and natural fiber, but synthetic fibers, amongst them polyester fiber, are preferred. The polyester fiber filaments are superior in rigidity to other synthetic I ~
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- ~)9S3~6 fibers and also have high repulsive elasticity, so that when used for cushion in the form of a locked material very satisfactoxy cushioning property can be obtained. Thus,.the filaments used accoxding to the invention are preferably of 50 - 3,000 denier, more preferably of 100 - 1,000 denier, the most preferably of 150 - 600 denier, and the total '~

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~ ~Si3~i denier i5 50,000 - 3,000,000 denier, preferably lO0,000 -

2,000,000 denier, the most pre~erably 150,000 - 1,000,000 denier.
The three-dimensioned crimp filament obtained according to the invention may be subjected to improvement oE the cushioning property and rigidity after refinement by solely filling it into a cushion or formed into a locked material by locking the intersections of the filaments with an adhesive into a predetermined form. This locked material may be used solely as the cushion or incorporated in another cushion for improving the cushioniny property and rigidity.
The term "two-dimensioned crimp" throughout the specification refers to what is regularly crimped in the form of a wave, and the term "three-dimensioned crimp"
refers to what is obtained by providing an additional crimp to this wave state.

BRIEF DESCRIP~ION OF THE DRAWINGS
The present invention will be understood best in conjunction with the accompanying drawings, in which:
Fig. l is a perspective view of the apparatus in accordance with the present invention;
Fig. 2 is a sectional view of the apparatus in accordance with the present invention;
Fig. 3 is an enlarged perspective view of the single twis-t means, , .
Fig~ 4 is a sectional view of Fig. 3 a]ong with a line IV - IV;

Fig. S is a sectional view of Fig. 3 along 3a with a ]ine V - V;
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~gS3~6 Fig. 6 is an enlarged sectional view of Fig. 1 along wi-th a line VI - VI;
Fig. 7 is a sectional view of a hea-ting means in another embodiment;
Fig. 8 is a perspective view of the double twlsted filaments; and Fig. 9 is a perspective view of the three-dimensioned crimp filament in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
As shown in Figs. 1 to 5, a filament supply inlet 1, a single twist transfer roller group 2, a guide means with a heating means 3l a twisting means 4 and tension drive means 5 are disposed in the mentioned order in the direction of feed of a filament. These individual parts will now be described in detail.
A plurality of filaments F approximakely uni-formly bundled at a filament supply inlet 1 are stretched to rollers 2 in a sing]e twist step. The rollers 2 com-prise a freely rotatable first roller 2a with a peripheralgroove and at least one other freely rotatable second roller 2b. Although it is desirahle that the second roller 2b also have a peripheral groove, it is not always necessary. If necessary, one or more rollers in addition to the second roller 2b may be provided, but these rollers may be provided coaxially with the first and second rollers 2a and 2b respectively by providing peripheral grooves and it is generally desirable to provide 3 - 4 or more of the grooves on each roller. It is necessary that the each roller provided coaxially have the same diameter. Thus ~7a-~g5~

the filaments F are set so that the portion of the double twist formed in a subsequent double twist step as shown in Figs. 1 r 3 and 5 is stretched to the first roller 2a having the groove and the single twist portion Fs is stretched to the second roller 2b and further the s~sequent filament F is stretched respectively to the rollers provided coaxially on the rollers 2a and 2b in order and finally it is connected to the filament supply inlet 1.
In such case, diameter D of the first roller 2a at the grooved portion should be 10 - 500 mm, prefer-ably 20 - 300 mm, most preferably 30 - 150, although it depends upon a total denier of the filaments to be usea, an angle e between the double twist portion Fd and the single twist portion Fs and the like. Further, the angle e between the double twist portion Fd and the single twist portion Fs as shown in Fig. 4 is preferably about 20 to about 70. If feed rate of the filament is increased, productivity increases, but it is required to enlarge both heating means and cooling means. Further, width of the left hand groove on the first roller 2a is preferably somewhat larger than the diameter of the double twist Fd but not so much as to permit the formation of a triple twist or more by further twisting in it. Instead of the groove, two plates may be mounted to the roller without any grooves vertically to an axis thereof at a distance like the above mentioned width. Further, when the plurality of rollers are arranged coaxially to the first and second rollers 2a and 2b respec-tively, it is desirable that the grooves on one roller be positioned 1~53~

between the grooves on another roller as shown in Fig. 5.
A guide 38 may be provided between the grooves as shown in Fig. 5. :~
A guide means 3 providing a heating means includes a pi.pe 3a through which the double twisted fila-ments Fd are passed, a jacket 3b on the outer side of the pipe 3a, a duct 3c for introducing h.igh pressure steam into the jacket 3b and an exhaust duct 3d. It is desired that an inner diameter of the pipe 3a is slightly 10 greater than that of double twisted filament so as to ;
prevent it being twisted further. Further, it is prefer~
able that a distance between the guide means (pipe 3a) ;~
and the first roller 2a is as little as possible.
Similarly, a distance between the below mentioned twist- ;
ing apparatus 4 and the guide means 3 is preferably as little as possible. And as the heating means 3, may be : used electric heating, infrared rays, high frequency heating and so forth~ Further, in order to increase the efficiency, the heating means may be constructed so as to . -~
heat also the whole single twist step including rollers 2a and 2b except part of the guide means, as shown in Fig. 7. In such case, the heated portion .of the guide means 3 may be small and may sometimes be omitted.
The twisting means 4 has two rotative discs 6 and 7 coupled together with two arms 8 and 9. The rota-tive discs 6 and 7 are provided at their center with respective hollow shafts 10 and 11. The shafts 10 and 11 are supported by respective bearings 12 and 13. ~ hollow shaft 14 for introduc.ing the filaments is rotatably fit~
ted in the interior of the shaft 10 on the side of :Eilament :~ .
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introduction. Diame-ter of the hollow shaft is preferably somewhat grea~er than that of the double tw:ist. The shaft 10 and hollow shaft 14 are provided at their ends with respec-tive spur gears 15 and 16. These spur cJears 15 and 16 are in mesh with respective spur gears 17 and 18 coaxially secured to a shaft 32 extending below them. These gears constitute a gear train. The hollow shaft 14 is provided at its other end on the side of the disc 6 with a sun gear 19 in mesh with planet gears 20 and 21 revolving therearound. Pair rollers 22 and 23 provided with rotary grooves are coupled via respective fixed shafts 24 and 25 to the planet gears 20 and 21. The rollers 22 and 23 are provided with respective grooves 22a and 23a such as to maintain proper transfer speed for forming the filament with double twist and suEficient cooling period to effect thermal set. The grooves 22a and 23a have wavy sectional profile such as to permit the filament formed with double twist to be pulled without causing slip~
Furtherl number of the grooves is decided in order to maintain a proper distance for cooling and a necessary length, and the ends of the fixed shafts 24 and 25 are coupled together by means of a bracket 26. Guide rollers 27 and 30 are provided via brackets 33 and 34 to the opposite sides of the center portion of the bracket 26. The arm 8 is provided with guide rollers 28 and 29 con~tituting with guide rollers 27 and 30 a guide roller group R arranged in a reverse U-shaped roller group in order to give a twisting action on the feed-in side and an l~twisting action on the feed-out side. The shaft 11 is provided at the end thereof with a drive pulley 31 secured thereto and coupled via a ~elt 35 to a pulley 35 connected to a power source 36. Instead of the pulleys 31 and 37 and the ~elt 35, sprockets and chain may be used.

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;34~i As the drive means for pul].ing filaments, it is preferable to provi.de a rotary cutter dri.ven by a torque motor as shown in Figs. 1, 2 and 6. The rotary cutter 5 com-prises a rotative disc 40 and rotakive ring 41 connected by a spider 39 and for~ing a drum-like annular channel 49. In the spider 39, there are provided many grooves in which are inserted knives 42 provided with a cutter edge facing radial-ly in a vertical direction across the channel 49, and are fixed by a knife retainer 43 which is fixed to the disc 40 by bolts 44. ~ hopper 45 for receiving cut stap~es is provided under the rotative ring 41. A shaft of the rotary cutter is connected to a transmission by a coupling 46 and further connected to a torque motor 48. The bundle of fila-ments are wound on the knife edges in layers, as shown ak 56, to provide anchorage for placing the filament bundle under tension and drawing it along the longitudinal pathway, and the end is continuously cut of in staple lengths by the following mechanism. Thus~ a push roller 50 is inserted into :
the annular channel49 formed between the rota-tive disk 40 and ;~
rotative ring 41 in a position to ride up on the outermost layer. The push roller 50 is mounted on a frame 52 by a swing arm 51 and is adjusted by movement of the swing arm to provide a gap between an edge of the knife 42 and the roller suffi-ciently narrow to cause the knives 42 to cut through the inner-most layer of bundles 56, but not to cut thxough the outermostlayer. The swing arm 51 is moved by a handle 53 connected to a socket 55 and to screw 54 rotation of which presses the roller 50 onto the outermost layer which/ in turn, presses the innermost layer into the cutting edge of kni~e 42 so that the innermos~ layer is continuously and successively cut into staple lengths when the roller 50 passes over a knife 42.

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Thereby the rotary cutter not only fwlctions as a drive for pull-ing -the ~mtwisted filaments but also as a cutter fo.r cu-tting them into staple lengths.
The method of manufacture of the above apparatus by using a three-dimensioned crimp fi].ament block will IIOW be described.
A plurality of filaments, for instance, synthetic fiber filaments, pulled out from a plurality of bobbins (not shown) are passed through -the filament supply inlet 1, passed round the rollers 2a and 2b in the single twist transfer roller group 2 as shown in Figs. 1, 3 and 5, passed through the pipe 3a of the guide means and through the hollow shaft 14, and passed round the guide roller 27 and round the rollers 22 and 23 with the respectively rotary grooves in the mentioned order, and then they are passed round the guide rollers 28, 29 and 30, passed through the shaft 11 and passed between -the drive means for pulling 5. .
Then, a motor 36 is driven to cause rotation of a pulley 31 in the clockwise direction so as to rotate the rotative discs 6 and 7 in the clockwise direction. As a result, the shaft 10 secured to the rotative disc 6 and the gear 15 coaxially secured to the shaft are rotated in the clockwise direction. Since the gear 17 in mesh with the gear 15 is rotated in the counterclockwise direction, thus causing rotation of the gear 1~ in the same.direction as the gear 17, the gear 16 and shaft 14 secured to the shaft are rotated in the clockwise direction. Further, a sun gear 19 secured to the hollow shaft 14 is rotated in the clockwise direct.ion similar to the rotative disc, but a different rotational speed. With the rotation of the sun gear 19 the ,~ :

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plane-t gears 20 and 21 are rotated in the opposite direction.
Consequently, an action of mutual twisting of a plurality of filaments F in the opposite direction is produced before and aEter the guide roller group R. That is to say, when the filamen-ts are pulled through a reverse U shaped pathway Eorm-ed by rollers 23, ~3, 29 and 30 under giving twist action, the twist action ~cts to the filaments at a first corner (roller 27) and spreads the double twist to the roller 2a, a fourth corner (roller 30) becomes a fulcrum for reverting the twist and produces effects for twisting and untwisting.
Driving force for feeding the filaments to a progressive direction send the twisted filaments by changing rotation number of the gear 16 by means of combination of gears 17 and 18 as the same rotation as the rotative discs 6 and 7 and the gear 15. Therefore, occurrence of uniform double twist based on total denier of the filaments, twisting and feeding is controlled by a ratio between the feeding and the twisting.
On one hand, the double twist as shown in Fig. 8 can be given to the filaments by twisting action given by means o~ the roller group R, but although the double twist Fd thus formed spreads to the first roller 2a, it does not spread to the filaments stretched between the rollers 2a and 2b and gives a partial twisting action to the filaments to form a single twist Fs. The roller 2a has such an effect in preventing the spread of the double twist, only when diameter of the roller 2a i5 within the above mentioned range. That is to say, when the diameter is less than 10 mm, it is too small relative to the size of the double twist formed from 50l000 -

3,000,000 of total denier while when the diameter is more than 500 mmf it is thought that the influence of corresponding ~31S3~6 tension becomes smal] and the pressing force loaded to the roller 2a is dispersed. Further, the reason why the filaments are stretched to the rollers 2a and 2b 2 - 4 times is to prevent, by Eriction between the rollers and the filament, the spreading of the double twist from the roller 2a due to the twisting stress which results from the length of the filaments becoming one-fourth that of the original length when the double twist is formed.
The filaments F provided with double twist are guided by the guide means 3 under heating not so as to set the twist and cooled down at roller group R to complete heat set.
Then, on the rear side of the roller 30 the fila-ments receive twisting action in the reverse direction, as the rotary cutters driven by a torque motor 48, especially at the position pushed by a swing roller 50 as a fulcrum, so the filaments are transferred under untwisting the double twist and are cut to a desired length, e.g., 30 - 300 mm, especially 50 - 150 mm by the knife 42 pushed by the swing roller 50 to obtain a staple fiber of a three-dimensioned crimp filament as shown in Fig. 9. The above-mentioned torque motor 48 is con-nected to an electric source by way of a transformer (not shown).
The rotary cutter used in the present invention is used as a fulcrum for untwisting the double twist, so it can give a necessary tension to the filaments and act as the cutting means at the same time. On the contrary, in the above mentioned apparatus, not only is the velocity of the double twisted filament variable depending upon the extent of the twist but also the untwisted filaments have crimp and are subject to stretching. Accordingly it is difficult to cut to a constant size ~mless the untwisted filaments are s-tretched ; . , 3L~ 34~

continuously by a proper tension. Thus the ahove-mentioned rotary cutter is driven by a torque motor, so the filaments are stretched continuously ~y a proper tension and it becomes possible to cut them at a constant size. There~ore, untwist-ing on relaxation of the fiiaments between both fulcrums,which is apt to occur when the conventional motor is used and disappearance of the crimp based on too strong tension and overload of the motor can be eliminated.
EXAMPLE I
An apparatus shown in Figs. 1 - 2 was operated by using a freely rotatable rollers 2a and 2b having peri-pheral grooves and having 80 mm of diameter the grooved portions arranged so that the angle e between the double twist portion and single twist portion is 45 as shown in Fig. 3 and stretching 300 denier of polyester filament as a mono-filament in 500,000 of total denier under 3.4 m/min of passing rate and 13 r.p.m. of rotation number of the roller 2a and the filaments were heat set at a temperature of 120 - 130 C. In this operation, spreading the double twist passed over the roller 2a was not observed at all. When untwisted fila-ment were cut by a rotary cutter 5 driven by a 30 kg/cm2 of a torque motor at a length of 80 mm, the lengths were constant.
E~AMPLE 2 A similar manner as Example 1 was carried out except that the diameter of the roller 2a was 40 mm, the total denier was 250,000 denier, rotation number of the roller 2a was 16 r.p.m. and the passing rate was 2~25 m/min. As the result of the operation, spreading the double t~ist passed over the roller 2a was not able to be recognized at all. When un-twisted filament were cut by a rotary cutter 5 driven by a 30kg/cm of a torque motor at a length of 70 mm, the lengths were constant.

Claims (9)

CLAIMS:

1. A method for manufacturing a three-dimensioned crimp filament comprising: twisting a bundle of large denier filaments into a single twist while said filaments are stretch-ed between a freely rotatable first roller with a peripheral groove having 10-500 mm of diameter at a grooved portion and at least one other freely-rotatable second roller in a total denier of 50,000 - 3,000,000 denier by means of twisting action in a subsequent double twist step; double twisting said single-twisted filaments into a double twist up to said first roller and heating the filaments thus twisted into a double twist while passing them through a tubular guide means;
cooling said double-twisted filaments to effect a heat-set while maintaining the twisting action; untwisting said double-twisted filaments thus heat-set to form three-dimensioned crimp filaments; and cutting said untwisted three-dimensioned crimp filaments into staple lengths, the diameter of said first roller at the grooved portion being correlated with the diameter of the double-twisted filaments formed from the 50,000-3,000,000 denier bundle to prevent the spread of the double twist back beyond said first roller under the tension necessary to form and maintain said double twist, and the width of said peripheral groove and the diameter of said tubular guide means being sufficient to freely receive the double-twisted filament, but insufficient to allow it to curl into a greater multiple twist.

2. A method according to Claim 1, wherein said first and second rollers are arranged so that an angle between the double twist portion and the single twist portion is between about 20° to about 70°.

3. A method according to Claim 2, wherein said cutting step is carried out by a rotaty cutter driven by a torque motor, whereby staple filaments of uniform length are obtained.

4. An apparatus for manufacturing a three-dimensioned crimp filament comprising: a single-twist roller group comprising a freely-rotatable, first transverse roller with a peripheral groove having 10-500 mm diameter at the groove portion and at least one other rotatable second transverse roller; drive means for pulling a bundle of filaments around said transverse rollers and up over and in said peripheral groove in a longitudinal pathway leading from such peripheral groove to said drive means; twisting means located ahead of said drive means adapted to give the portions of said bundle of filaments forward and rearward of said twisting means, while stretched along said longi-tudinal pathway and around said transverse rollers and pulled along by said drive means mutually opposite twist-ing actions, whereby the portion of the forward portion ahead of said peripheral groove is given a single twist, the portion thereof between said peripheral groove and said twisting means, a double twist, and the rearward portion from said twisting means to said drive means is untwisted;
tubular guide means provided ahead of said twisting means for the filaments formed with a double twist; heating means serving to heat the said double-twisted filaments to a temperature such that, on cooling, the crimp in said fila-ments is given a permanent heat-set, whereby untwisting results in a three dimensional crimp filament; and, cutting means for cutting the three-dimensioned crimp filament into staple lengths while under tension, the diameter of said first roller at the grooved portion being correlated with the diameter of the double-twisted filaments formed from said bundle to prevent the spread of the double twist back beyond said first roller under the tension necessary to form and maintain said double twist, and the width of said peripheral groove and the diameter of said tubular guide means being sufficient to freely receive the double-twisted filament, but insufficient to allow it to curl into a greater multiple twist.

5. An apparatus according to claim 4, wherein said first and second rollers are arranged so that an angle between the double twist portion and the single twist portion is between about 20° to about 70°.

6. An apparatus according to claim 5, wherein said cutting means for the untwisted filaments and said drive means for pulling the filaments comprises a rotary cutter driven by a torque motor.

7. An apparatus according to claim 5, wherein the single twist means comprises two freely rotatable rollers respectively having plurality of grooves and having same diameter.

8. A method according to claim 1, in which the cutting step and the pulling step are effected simultaneously by winding the untwisted, heat-set double-twisted filament bundle in multiple layers on a drum and cutting the lower-most layer into staple lengths while leaving the outermost layer intact.

9. Apparatus according to claim 4, in which said cutting means and said drive means comprise means for wind-ing the untwisted, heat-set, double-twisted filament bundle in multiple layers on a drum and means for cutting the lower-most layer into staple lengths while leaving the outermost layer intact.