US3619874A - Travelling-edge crimper and process - Google Patents

Abstract

A THERMOPLASTIC YARN IS CRIMPED AT INCREASED SPEEDS BY GUIDING A RUNNING LENGTH OF THE YARN UNDER CONTROLLED TENSION AND TEMPERATURE AT AN ACUTE ANGLE OVER AN EDGE IN AN APPARATUS IN WHICH THE CRIMPING EDGE ITSELF TRAVELS IN A DIRECTION WITH THE MOVING YARN.

Description

NOV. 16, 1971 m. LANG E'I'AL 3,619,874

TRAVELLING-EDGE CRIMPER AND PROCESS 3 Sheets-Sheet 1 Filed Jan. 16, 1970 IN VENTORS HSIN LANG u DUSAN c. PREVORSEK Y HENDRIKUS J. OSWALD Afr gle/vm NOY. 16, 1971 sm, LANG EI'AL 3,619,814

TRAVELLINC-EDGE CRIMPER AND PROCESS I5 Sheets-Shet 2 Filed Jan. 16, 1970 m QR INVENTORS HSIN LANG Ll DUSAN C. PREVORSEK HENDRIKUS J. OSWALD Qua.

TTORN E Y NOV, 16, 1971 sm, L ETAL 3,619,874

TRAVELLING-EDGE CRIMPER AND PROCESS Filed Jan. 16, 1970 3 Sheets-Sheet 3 FIG. 3

INVENTORS HSIN LANG Ll DUSAN C. PREVORSEK HENDRIKUS J. OSWALD W A R/VEY US. Cl. 281.5 Claims ABSTRACT OF THE DISCLOSURE A thermoplastic yarn is crimped at increased speeds by guiding a running length of the yarn under controlled tension and temperature at an acute angle over an edge in an apparatus in which the crimping edge itself travels in a direction with the moving yarn.

BACKGROUND OF THE INVENTION It is well known in the art that, under proper conditions, passing of a thermoplastic yarn under tension in a sharp angular path about an edge positioned at the apex of the angle will impart to said yarn a general permanent tendency to coil or crimp. Apparatus for effecting crimping in this manner is disclosed, for example, in US. Pats. 2,919,534; 2,921,358; 3,025,584 and 3,325,888.

In its simplest form, the degree of crimping depends upon many factors such as yarn tension, yarn diameter, temperature of the yarn and the blade, geometry of the blade, angle of inclination of the filament at the entry to the blade axis, etc. The principal action of the process takes place in the compression zone at the inside of the bend; in the extension zone at the outside of the bend, the material remains largely unaffected.

The magnitude of structural changes which involve general disorientation and distortion of crystallites and which in turn impart to the yarn the desired tendency to coil is in addition to the above-stated factors dependent also on the time a section of the yarn remains in the zone of constraint at the tip of the edge. In order to have functional macrostructural changes taking place deep within the compression zone, the action time must exceed a given lower limit that, of course, depends upon experimental conditions and the type of fiber. Since the residency time of a fiber section in the zone of contact With the blade is a function of the linear speed of yarn, the foregoing conditions impose severe limitations on the linear speeds of yarn at which one can operate and achieve the desired crimping effects on yarns or monofil.

Production rates are further limited by the frictional and deformational effects that lead to general increase in yarn tension which, in turn, may cause yarns or monofilaments to break if the processing rates are too high.

Consequently, this process can operate satisfactorily only at relatively slow linear speeds of yarn. These limitations represent great economic disadvantages of this method.

SUMMARY OF THE INVENTION We have discovered that these problems can be overcome and the linear speeds of the yarn increased by a substantial factor, e.g., up to ten times or more, if the crimping is carried out in an apparatus in which the travelling crimping element is parallel with a moving yarn at a speed that is faster, or slower, than that of the moving yarn. The movement of the edge is in the same direction as the running yarn.

In essence, the apparatus comprises a rotating element over which the yarn is driven in combination with a relatively sharp edge that moves in the same direction as the yarn and whose rate of movement is coordinated or synchronized with the movement of the yarn. The

3,619,874 Patented Nov. 16, 1971 edge itself, over which the yarn is drawn in sliding frictional engagement, may comprise any suitable configuration, e.g., a knife edge (a blade, a helical blade, and the like). The yarn is heated, at the appropriate tempera ture for the particular thermoplastic composition comprising the yarn, in a suitable manner such as by heat applied on or contiguous to the crimping edge or by heating the roller or other yarn-tensioning and/0r yamtension release means associated with the travelling crimping edge.

It is an object of the invention to provide a novel method and an apparatus for producing crimped thermoplastic yarn at a substantially increased rate of produc tion to yield a textured yarn of uniformly high quality.

The foregoing and additional objects are accomplished by means of an arrangement that includes a yarn supply, a yarn tension controlling mechanism, a yarn temperature regulating means, a travelling edge (preferably rotating) over which the yarn is moved in relative frictional sliding engagement and a crimped yarn-collecting device.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a schematic view in perspective of one embodiment of a yarn-crimping apparatus in which a rotating element carries both the crimping blade and a heating element for the yarn mounted contiguous to the blade;

FIG. 2 is a schematic view in perspective of an alternate embodiment, wherein the yarn-crimping edge cornprises a helix configuration;

FIG. 3 is a schematic view in perspective of still another embodiment in which the path of the travelling yarn-crimping edge follows a concentric path around the rotating yarn tension-regulating roller.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to 'FIG. 1, yarn 12, to be crimped, is taken off yarn supply bobbin 11 or, alternately, the yarn may be supplied without prior storage from conventional extruding apparatus (not shown) after suitable routine treatment such as extrusion and drawing of the yarn. The

' yarn 12 is passed through tension-regulating device 13 of the kind known in the art and yarn guide 14 and thereafter is wrapped around a rotor arrangement 10 comprising end mounts or plates 29, a first guide roller 15, a second guide roller 16, the rotating heater 25, and then the knife edge 21. Each of the elements 15, 16 and 25 are mounted on rotor frame end mounts 29. The rotor frame 10 is driven appropriately by a motor 42 through a shaft 43 and rotates about the center of shaft 17. On shaft 43, a pair of brushes (not shown) and slip rings 26 are installed where electrical current flows from slip rings 26 by electrical connection to the heater 25. The distance between heater 25 and the blade 24 may be appropriately adjusted by moving the heater 25 up or down in the slot 20. Optionally, the roller 16 may be arranged to being suitably driven to provide improved tension control on the yarn such as by motor 53 c0nnected to slip rings on shaft 17 through leads 54.

After the yarn 30 passes over the edge 21 of the blade 24 for the first time, the tension on the yarn at 31 is increased and must be reduced before it passes over the blade for the second and third times, otherwise, it results in yarn breakage owing to progressively increasing tensile force on the yarn on each passage over the edge 21. The tension-reducing device is essentially a motor-driven godet 51 and separator roll 50. After yarn 31 passes over the godet roll 51, the tension on yarn 32 is reduced to the original level of tension of the yarn at the point shown by reference 12 originally fed to rotor 10. Yarn 32, now under lower tension, may optionally, but pref erably, be again wrapped around the second guide roll 16, heater and edge 21. As soon as yarn 32 passes edge 21, tension on yarn 33 is again increased. The procedure of passing over the edge and reducing the tension may be repeated as often as desired. The yarn may again be wrapped around the heater 25 and blade 21 for the final wrap; the intermittent tension-reducing step may be omitted unless further tension buildup circuits of the yarn are contemplated. Yarn 38 may then be conventionally wound around the godet roll 51 before it is taken up by a yarn winder. As shown, the same godet 51 may be employed to lessen tension on yarn 38 before it is wound on storage bobbin 52.

Referring to the alternate embodiment, FIG. 2, yarn 62 provided from a suitable supply 61 passes through a yarn tension-regulating device 63 to guide device 74. From guide 74, the yarn passes over the heater 65, which is heated through brushes (not shown) and slip rings 88, and helical edge 64. Helical edge 64 is mounted on a first step roller 98 where its blade starts from a 12-oclock position at the left side of roller 98 and ends at the 6-oclock position at the extreme right side of roller 98. In other words, for every half revolution of roller 98, the tip of helical edge faces l2-oclock position while at this position, the yarn guide 74 mounted on the traverse extension bar moves from the extreme left to right. Regardless of the differential speed between the edge 64 and the moving yarn 62, once the roller 98 makes one complete revolution, part of the yarn is crimped while the other part 81 is uncrimped between first stage roller 98 and second stage roller 00. The second stage roller is constructed essentially identically to the first stage roller 98, except that the helical edge 91 and heater 92 are analogous to a right-handed screw, while helical edge 64 and heater 65 on the first stage roller 98 are lefthanded." This arrangement facilitates control over the to-and-fro movement of the yarn. Roller 90 is driven by a motor (not shown) through the main driven pulley and belt '98. The timing gears 97 and 67 are identical in geometrical size and are connected by a timing belt 68. The length of the belt 68, or the distance between the centers of rolls 98 and 90 are adjusted in a manner such that the edge 91 will crimp essentially only the uncrimped portion of yarn 81. The pigtail guides 74, mounted on bar holder 71, are reciprocated as cam BB follows grooves 69A formed in cam 69. Cam 69 is suitably driven by a pulley 70 and drive-belt arrangement 95. After the yarn passes over edge 91, essentially completely crimped yarn 82 is produced. The tension on yarn 82 is appropriately reduced by a motor-driven godet roll arrangement 101 and 100 before yarn 87 is wound on a winder 102. It should be noted that a tension-regulating device similar to that shown by reference numbers 101 and 100 may be installed between the first and the second stage rollers 90 and 98, if desired.

Referring to the embodiment of FIG. 3, yarn 112, supplied from source 111, is fed to a yarn tension-regulating device 113 and guide device 114. From the guide 114, the yarn is wrapped aroung the godet roll 128 in such a way that the tension on the yarn 130 is reduced to an optimum value prior to passing it over the crimping edge 121. The yarn 130, hereafter referred to by this reference numeral as being on the low tension side, passes over the heater and edge 121 of blade 124. Heater 125 is heated electrically in a conventional manner as current flows through wires 129, a pair of slip rings 125,

and carbon brushes (not shown). The temperature of heater 125 is regulated by a thermocouple 137 and a slip ring arrangement 135.

After yarn passes over heater 125 and edge 121, the tension on yarn 131 is increased owing to the frictional drag. The process is then repeated with as many wraps on moving edge 121 and driven godet .roll 128 as it is required before yam 144 is wound on winder 151. Instead of the edge 121, other appropriate crimping elements, e.g., a wire of suitable diameter (not shown), may be alternatively used as the crimping edge. The godet roll 128 has a surface which may be smooth or knarled, serrated, coated, etc.; it is mounted on axle 143 and supported in mounting 115 and is driven by motor (not shown) connected through a pulley 138 and drive belt 142. A separate drive operating through drive pulley 133 and belt 134- rotates the knife frame 120, which carries knife 124, knife holder 116 and heater 125, each of which is mounted on the carrier 123. Both the heater 125 and the blade 124 can be moved within a slot 145. The mounting position of blade 124 in the slot controls the yarn approach and departure angles with respect to the crimping blade 124. Moreover, the blade holder 116 may be arranged to have a three-dimension adjustment (not shown) for maximum crimping stability. While reference is made to two motors, it will be apparent that one motor is sufiicient to drive both the godet roll 128 and the planetary mounting frame 120, which carries the crimping knife, may be used with proper selection of gear ratios to provide the desired relative rotation. The godet roll 128 rotates about its axis while edge 121 resolves around the godet roll 128 similar to a planetary motion. It will be apparent that the godet 128 illustrated may be substituted by an alternate shape such as a moving belt to give essentially an elliptical, instead of a circular, path.

The following examples will further illustrate the in vention.

Example 1 Thoroughly dried nylon =6 polymer chips having a number average molecular weight of 20,000 was melt spun using a screw-type extruder in which barrel and die temperatures were maintained at 260 C. and 270 C., respectively.

The spinneret used had three holes, each having a capillary diameter of 0.020 and length of 0.100. An air-quenching system was used to solidify the filaments, which were taken up with a yarn winder at a speed of 700 feet per minute. Each filament of the yarn had a diameter of 0.004".

The spun and solidified filaments were then drawn using a conventional pin-block heating arrangement with temperatures of 80 C. and C., respectively.

These filaments were then treated in the crimping apparatus of the kind shown schematically in FIG. 1. The tension on the 45denier (3 filaments) yarn was maintained at 2.4 grams before passing over the edge. The crimping edge, first guide roller and second guide roller are spaced equally 120 apart and 3 away from the center of the shaft driving the main rotor frame. The edge of the blade used has a diameter of 0.001 approximately, and the tangential surface speed of the edge was 750 f.p.m., while the take-up or yarn-winder speed was 1000 f.p.rn. The yarn was wrapped one complete turn around the rotating edge crimper, and the tension after one complete wrap was increased to 27 grams. The filament was then wrapped around the 6diameter, motor-driven, godet roll and the separator roll twice to reduce the fiber tension to 2.4 grams before it was wrapped around the rotating edge crimper for the second time.

This procedure was repeated five times around the edge, motor-driven godet roll, and separator roll. The yarn was crimped over its entire length.

Each filament of the yarn had a helical appearance with a relaxed diameter of 1 mm. and 30 helical turns per inch after heat treatment in a steam environment at a temperature of 105 C.

Example 2 Fiber was extruded, drawn and prepared using the same procedures described in Example 1, except the three filaments of the drawn yarn were wound separately on three separate bobbins. The -denier nylon 6 monofilament on each bobbin was crimped using the crimper shown schematically in FIG. 3.

In FIG. 3, the godet roll diameter is 6" and the tip of the edge is adjusted 6" away from the center of the godet roll and the angle of approach and departure of the monofilament to the edge was and respectively. The heater temperature was maintained at 110 C. The rotational speed of the godet and the edge were 728 r.p.m. and 596 rpm, respectively. The fiber was wrapped around the godet roll and edge four times before it was taken up on a winder at a speed of 1360 f.p.m. On this pass, of the fiber was crimped, measured along the axial length of the fiber. In some cases, this partial crimping may be advantageous, and it will be understood that the apparatus of the invention allows practically any proportional segment, or all of the yarn, to be crimped. To produce a more fully crimped yarn, the number of total wraps around the edge were increased to eight times under otherwise identical conditions. Completely crimped fiber was observed. The crimped fiber has a relaxed diameter of 1.2 mm. and 30 helical turns per inch after heat treatment in a steam environment at a temperature of 105 C. approximately.

A similar run was made with a nylon 6, -denier (32 filaments) yarn and with polyester -denier (36 filaments) yarn with essentially the same advantageous result.

Various modifications will be apparent to one skilled in the art, and it is not intended that this invention be limited to the details in the specific drawings and description and by way of examples which are presented by way of illustration. Accordingly, the scope of the invention is limited only by the appended claims.

We claim:

1. In a process for texturizing thermoplastic filament yarn by drawing yarn which is under tension in frictional engagement over a crimping element, the improvement which comprises advancing the crimping element in the direction of movement of the yarn and maintaining a relative movement between the yarn which is being texturized on said crimping element and the movement of the crimping element.

2. The process of claim 1 wherein said moving element travels in essentially a cylindrical path.

3. The process of claim 1 wherein said moving element is a sharp edge.

4. The process of claim 3 in which the yarn frictionally engages a plurality of knife-like edges.

5. Apparatus for texturizing thermoplastic filament yarn comprising a travelling element over which yarn moving at a difierential speed relative to said element and in the same direction is drawn in frictional engagement therewith, means to draw a yarn under tension and in texture imparting engagement with said travelling element and at a differential speed with respect to said element, means to support the travelling element and controlled driving means for and to maintain a desired differential speed between the movement of the yarn to be textured on the travelling element and the movement of said element.

6. The apparatus of claim 5 wherein the travelling element comprises a plurality of knife-like edges.

7. The apparatus of claim 5 which incorporates a tension release means to lessen tension on the yarn after the yarn has frictionally engaged the travelling element.

8. The apparatus of claim 7 in which a tension release godet roll is used in combination with a rotary travellingedge unit which encompasses a temperature-regulating element positioned contiguous to the texturizing element.

9. The apparatus of claim 5 which incorporates a helical travelling edge.

10. The apparatus of claim 7 in which the travelling edge moves so as to describe a concentric circle around a rotary tension-release means.

References Cited UNITED STATES PATENTS 2,825,199 3/1958 Hicks 57-36 3,035,396 5/1962 Biggers 2872.13 X

3,360,838 1/1968 Comer et a1. 2872.13

FOREIGN PATENTS 564,382 10/1958 Canada 28-72.l3

LOUIS K. RIMRODT, Primary Examiner U.S. Cl. X.R. 2872.13

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