IL22327A - Texturing and crimping filament yarn - Google Patents

Description

This invention relates to a method and apparatus for continuously stretching and continuously deforming substantially parallel synthetic continuous textile filaments formed from a thermoplastic polymer, and particularly filaments of the nylon type, whereby such filaments are rendered more resistant to inter-filament slippage. More specifically, this invention relates to a method and apparatus for improving filament cohesion of nylon continuous filament yarn.

Continuous synthetic cold-drawable filaments can be formed from nylon polymers and the like by the wet, dry, or melt spinning processes, the last mentioned process being employed in the commercial production of most, if not all, of the nylon filaments made today. The freshly formed nylon filaments generally are not highly oriented and have relatively low tensile strengths as compared to highly oriented nylon filaments in which the molecules are aligned or oriented in the direction of the filament axis. To orient nylon filaments and thereby to increase greatly the strength thereof, they may be stretched to a desired extent by attentuating them by means of thread advancing devices such as two godets or two other thread advancing means operated at a predetermined peripheral speed differential. In the cold-drawing of continuous filaments of nylon it is known that stretching is accomplished advantageously when the point at which stretching occurs is fixed or localized by mechanical or thermal means. The localization of the stretch point is carried out ordinarily with the employment of a yarn braking device or the like located between two stretching roll de- advantage of greater evenness and superior strength, they have several undesirable properties including low heat insulating values, lack of bulkiness desired for some end uses, low covering power, poor tuft definition, and poor filament cohesion. Many attempts have been made in the past to impart to continuous filament yarn some of the desirable properties that are inherent in spun yarn.

Unlike wool, synthetic filaments are relatively straight and have a smooth, slick surface, thereby not being particularly adapted for spinning into spun yarn by the conventional spinning systems. To facilitate the carding and/or combing and drafting operations to which synthetic staple fibers are subjected in connection with spinning them into spun yarn, it is essential to crimp them so that they will have a satisfactory contour or pattern to permit spinning thereof into spun yarn by means of conventional textile processing equipment. Numerous devices and processes have been proposed to impart this desired crimp or crinkle to synthetic continuous filaments. One known form of a crimping device uses toothed gearing or serrated wheels which are heated and adapted to receive the straight continuous filaments and to impart a potential or temporary crimp to them by compressive forces. The potential crimp is later developed by reheating the filamentary material during dyeing or a steaming operation after the filaments have been processed and converted into articles of manufacture. As taught by the prior art, the potential crimp may be developed prior to take up of the potentially crimped filaments by passing the same, while relaxed, through a heated chamber are deformed by the toothed gears during the stretching operation to impart a memory of the deformation to the filaments. After advancing from the gears, the filament regain their original shape and remain straight until heated, at which t me^ the filaments assume the deformed or crimped configuration previously caused by the gears, whereby a permanent crimp is imparted to the filaments.

In certain manufacturing processes, as for example, tufting operations and the like, it is preferable to produce the articles of manufacture prior to developing the original potential crimp of the filaments. This presents a serious problem to the textile industry because the yarn does not possess a high degree of filament cohesion. This lack of cohesion allows a filament splaying condition to occur which adversely affects the processing thereof on conventional textile equipment, particularly tufting operations. In the case of staple fiber the filament cohesion is so poor that its use in producing spun yarns is not practical. However, it has been found that filamentary cohesion is increased substantially when a yarn is first crimped while hot, and subsequently crimped in a stuffer box while cold. A particular advantage of the cold crimp is that an actual crimp is imparted to the yarn without disturbing the original potential crimp. Therefore, the yarn can be processed efficiently prior to development of the original potential crimp. With this in mind, an object of this invention is to provide a method for improving the filament cohesion of synthetic filaments by increasing inter-filament resistance to slippage.

Another ob ect of this invention is to rovide of synthetic filaments by increasing inter-filament resistance to slippage.

Another object of this invention is to provide a method for imparting a crimped condition to synthetic filaments of nylon and the like.

Another object of this invention is to provide an apparatus for imparting crimped condition to synthetic filaments of nylon and the like.

Another object of this invention is to provide a novel and improved method for treating a yarn.

Another object of this invention is to provide a novel and improved yarn treating apparatus.

Still objects of this invention are to provide a method and apparatus for drawing, deforming, and crimping nylon filaments in a single operation so as to improve filament cohesion, tuft definition, covering ability, dyeing and the like while eliminating filament splaying, row definition, and a subsequent twisting operation.

A further object of this invention is to pro-vide a novel and improved apparatus for pre-conditioning nylon filaments so as to permit processing of staple fiber formed therefrom on conventional equipment without loss of bulk.

Other objects and advantages of the present invention will become apparent from a study of the following specification, claims, and drawing. A preferred embodiment of the apparatus of the present invention will now be described vrith reference to the accompanying drawing wherein? Figure 1 discloses a schematic view in perspec-tive with principal elements in location illustratin possessing a high degree of cohesion among said filaments; and Figure 2 is an enlarged cross- sectional view of the stuf er box.

In accordance with the present invention there is provided an improved stretching and deforming machine for processing nylon or like synthetic continuous filament yarn, the machine being constructed for highly efficient and economical operation. This is accomplished by the novel construction and arrangement of a feed roll assembly wherein at least one of the rolls is positively driven and a set of drawing and deforming toothed wheel members, together with means for heating the yarn such as a heated draw or stretch pin, a heated plate, a heated tube, and the like interposed between the said roll assembly and said members. Prom a suitable source the yarn is fed to the feed roll assembly after passing around or through a suitable tensioning device. The objective of the roll assembly is the provision of a supply of yarn at a predetermined rate and to guard against slippage of the yarn because of stretch tension subsequently applied.

Positioned in the yarn path forward of the roll assembly and heating means is a pair of crimping gears driven in unison and intermeshing in close relationship without coming in contact with each other. At least one of the crimping gears is positively driven at a predetermined increased speed relative to delivery speed of the roll assembly such that a stretch is imparted to the yarn between the roll assembly and gears. In operation the yarn is directed between the gears and preferably around part of the periphery of one of the gears and thence around an idle roll ) respect to the point where the yarn initially is passed between the gears. By proper spacing of the idle roll relative to the crimping gears, the yarn is intermittently engaged and disengaged between the crimping members either in a random or definite pattern. Temperature of the crimping members is maintained at a desired level by a coolant gas being directed on one of the said members.

Thereafter, the yarn is advanced vertically downwardly into a stuffer box by a pair of feed rolls associated therewith. The stuffer box is provided with a clapper bar which restricts the movement of the yarn thereby causing a back- ressure to develop within the stuffer box chamber. Consequently, the yarn assumes a position in the chamber in the form of a series of folded layers and is compressed therein to impart a crimped condition to the folded yarn at each bend of the said yarn. The cold crimp imparted to the yarn improves the inter-filament resistance to slippage of the filaments comprising the yarn. After being stretched, deformed and crimped in such manner as described herein above, the yarn is taken up in a well known manner.

In the continuous filament yarn treating apparatus shown schematically in Figure 1, a thermoplastic cold-drawable yarn 10, such a nylon or the like, composed of a bundle of smooth, substantially parallel filaments that have not been fully oriented, is supplied from a yarn source 11 on a bobbin 12. Since the yarn is not completely oriented, it is necessary to extend the yarn to be processed in order to obtain the optimum degree of molecular orientation therein. The yarn source can be, for example, yarn package 11 doffed machine.

In operation, as shown, the yarn 10 is passed over and around one end of the bobbin 12 and is threaded conventionally around a snubbing bar 13 which functions as a simple tensioning device to assist in maintaining an orderly and uniform supply of yarn. Prom the tensioning device or bar 13 the yarn 10 is passed through a yarn guide ll| and then to a pair of feed rolls l£ that withdraw the yarn from the bobbin 12 and supply it at a predetermined delivery speed. The rolls 15 have parallel axes and engage each other in operation to nip sufficiently the yarn passing therethrough so that slippage or free-flight of the yarn between the rolls is prevented.

Prom the feed rolls 1 the yarn 10 is led downwardly and around a heated stretch or draw pin 16 of a well known type where the majority of the attenuation of the yarn occurs. The pin, mounted so that it is axially askew with respect to the axes of the feed rolls If?, has a smooth yarn contact surface. After being passed around the heated pin 16 a desired number of times, the yarn 10 is directed downwardly between rotatably mounted and axially parallel crimping gears 17 and 18 positioned immediately beneath the pin l6 and having a plurality of uniformly circumferentially spaced and longitudinally extending teeth 20 that mesh in closely spaced adjustment. The gears 17 and 18 are keyed to shafts 21 and 22 , respectively. To drive the crimping gears in unison there are provided meshing spun gears 23 and 2ί mounted on the shafts 21 and 22, the shaft 22 being driven by a motor 19 of a well known type. intensity as the yarn approaches and leaves the horizontal plane in which the axes of the crimping gears lie and where said teeth engage the notches defined by said teeth to the greatest extent. After being directed around part of the periphery of the gear 17 the yarn is directed tangentially therefrom and then around part of the periphery of an idle roll 25 spaced from the gear 17 and mounted on a supporting frame 26, only a fragment thereof being shown. The frame 26 also supports the other parts of the apparatus. The yarn is wound around the gear 17 and the idle roll 25 "to form a plurality of wraps as shown in the drawing. The axis of the roll 25 is positioned at a slightly inclined angle with respect to the axes of the gears 17 and l8 so as to insure proper longitudinal distribution on gear 17 and roll 25 and advancement along the peripheries there of, thus preventing superposition of the wraps thereon. In other words, the yarn wrapped around the gear 17 and the horizontally spaced idle roll 25 assumes generally the shape of a flattened helix, the convolutions of which being spaced apart, so that the yarn advances along the gear 1 from the inboard to the outboard thereof during rotation of the gears 17 and 18.

To insure that uniform results are obtained in the crimping operation, an air nozzle 3k is provided.

The nozzle 3k is connected to a source 33 of cool air or other gas. The nozzel 3J- extends between the yarn wraps on the gear 17 and the idle roll 25 and is curved at the end to direct cooling air onto the gear 17. Stated in another way, the nozzle 3^· extends into the central part of the flattened helix defined by the yarn wraps and then bends toward the gear 17· The nozzle 3^- s positioned to direct a stream of cooling air onto the crimping gear 17 but not nto the moving yarn 10. This permits the yarn 10 to re ain its' heat while at the same time holding down the temperature of the gear 17. Since the yarn 10 is not wrapped around the crimping gear 18 , it is not necessary to cool this gear.

It is well known that temperature has great importance in the crimping of thermoplastic yarns. Thus, the temperature of the gear 17 will have an on the crimping operation. If the temperature of the gear 17 is permitted to vary widely the result will be wide variations in the crimped characteristics of the yarn. In fact, without the air nozzle 3k» the temperature of the crimping gear 17 would slowly rise as the heated yarn is moved over it. This would naturally cause changes in the final characteristics of the yarn. By using the stream of air to cool the gear 17, a substantially uniform result is achieved, since the crimping gear 17 is cooled to prevent undesirable temperature rises. Accordingly, the yarn is somewhat cooler when leaving the crimping gears than the heated yarn advanced to the crimping gears.

After forming the outermost convolution of the helix, the yarn is fed vertically downwardly between a pair of feed rolls 35 and 36 positioned immediately below crimping gears 17 and 18. The rolls 35 and 36 are keyed to shafts 37 and 38 , respectively, and are driven by any well known suitable means, not shown.

As illustrated by Pigur 2 , a istuffer box compris-rRg- a pair of doctor blades J.0 and 1+1 ,( are positioned directly below and adjacent to the feed rolls to form a blade 1+1 is mounted an air cylinder 1+3 for actuating bar 1+2 to vary the opening in the bottom of the stuffer box chamber. Movement of the yarn through the chamber is restricted by the clapper bar 1+2 while the feed rolls force the yarn into the stuffer box at a predetermined constant rate whereby a back-pressure is developed therein causing the said yarn to be folded and packed in the form of uniform layers 1+1+ in the chamber. The pressure exerted on the folded layers of the yarn in the stuffer box chamber imparts a crimp or crinkle at each bend 1+5 in the yarn.

The crimping operation performed by the stuffer box 39 greatly increases the inter-filament resistance to slippage of the filaments thereby improving filamentary cohesion. This improvement is accomplished by reason of the fact that actual crimp is imparted to the yarn without requiring reheating thereof to enable processing of the yarn prior to development of the original crimp. Prom studying the schematic of the apparatus illustrated it becomes apparent that the texturized ya n is crimped initially by gears 17 and 18 while heated, and immediately thereafter, actual secondary crimp is imparted to the yarn, when cold, by stuffer box 39· Without the cold crimp, the yarn is comprised of a plurality of straight continuous filaments having poor filament cohesion.

Prom the stuffer box 39 the yarn is fed vertically downwardly through a yarn pigtai^ guide 1+8 , which is mounted below the stuffer box. The yarn is then taken up in a conventional manner by a suitable form of package building apparatus such as a ring twist assembly which com- rises a bobbin 1 ada ted to be rotated b driven belt 1 8 assembly further includes a conventional vertically reciprocated ring 0 carrying a traveler $1 adapted to revolve freely around the bobbin I.6 as the yarn is twisted a desired amount and wound onto the bobbin.

It is to be understood that this embodiment of the invention may be altered or modified and that other embodiments may be contemplated without departing from the scope of the invention.

Claims (9)

HAVING SOB particularly described and ascertained the nature of our invention and in what manner the same is to ¾e performed, we declare that ushat we claim is t-

1. A method for improving the filament cohesion of nylon continuous filament yarn comprising the steps ί a. continuously deforming a heated and stretched yarn into a corrugated shape while simultaneously cooling the said yarn, b. thereafter successively imparting a permanent cold crimp to the said yarn, and c. collecting the crimped yarn in a suitable manner.

2. The method of Claim 1, characterized by continuously passing a yarn through a heat- stretch zone and deforming the cooled yarn into a corrugated shape to impart a cold crimp thereto.

3. The method of Claim 2, characterized by providing a source of continuous filament yarn and continuously compressing the cooled yarn in folded layers to impart a cold crimp thereto. i .

4. The method of Claim >» characterized by providing a source of a molecularly orientable nylon continuous filament yarnj continuously passing said yarn through a heat stretch zone, heating the yarn in s aid zone to an elevated temperature and attenuating the yarn in said zone a predetermined amount to increase the molecular orientation thereof, the majority of the attenuation being localized in the area where the yarn is heated; deforming the heated and stretched yarn into a corrugated shape by continuously simultaneously being cooled, successive portions of the yarn being subjected to forces laterally applied by the teeth of said gears alternately in one direction and then in the opposite direction to cause deformation of the yarn mostly along the apices of the teeth thereby imparting a memory of said deformation to said yarnj intermittently redeforming the yarn into a corrugated shape a plurality of times by passing same between said gears at predetermined intervals a corresponding number of times, reducing the tension on the yarn between each successive engagement of the yarn and said gears, and successively forcing the cooled yarn into a chamber, said yarn being folded and compressed therein to impart a permanent crimp in said yarn thereby improving filament cohesion thereof prior to collection thereof.

5. An apparatus for crimping a yarn characterized by comprising a pair of driven crimping gears for crimping a heated yarn and a pair of driven feed rolls for drawing the yarn from the said gears and forcing same into a stuffer box having a clapper bar disposed therein for imparting an actual crimp to said yarn.

6. The apparatus of Claim 5, characterized by a frame, an idle roll mounted on the frame and positioned from the crimping gears for cooperating with said gears to form a plurality of yarn wraps, said crimping gears are rotatably mounted on the frame, means for directing a cooling fluid onto said crimping gear to cool the yarn, and means disposed vertically downwardly from said crimping gears for crimping the cooled yarn.

7. The apparatus of Claim 6, characterized in that said idle roll cooperates with one gear to form a yarn engages only a portion of said one gear, and said feed rolls having a stuffer box connected therewith are mounted to the frame in tandem with the crimping gears*

8. The apparatus of claim 7» characterized by a pair of rotatably mounted rolls for advancing a yarn at a predetermined rate from a supply, and a yarn heating device in the yarn path between the advancing rolls and the crimping gears to heat said yarn.

9. The apparatus of claim 8, characterized in that said stuffer box chamber comprises a pair of feed rolls and a pair of doctor blades, said chamber having a passageway therethrough for receiving the yarn, one of said doctor blades having a clapper bar mounted thereto for restricting movement of said yarn through said chamber to develop a back-pressure therein, whereupon the yarn assumes the position of a series of layers in the stuffer box chamber thereby imparting a permanent cold crimped configuration to the yarn. 10* A method for improving the filament cohesion of nylon continuous filament yarn substantially as described herein and claimed in any one of claims 1 to k» 11 o An apparatus for crimping a yarn substantially as described and illustrated in the accompanying drawing. 2. Yarn whenever produced by the method claimed in any one of claims 1 to k and 10, or by the apparatus claimed in any one of claims 5 to 9 and 11· Bated this Twenty-third day of October Agent for Applicants