US3680302A

US3680302A - False twisting apparatus

Info

Publication number: US3680302A
Application number: US83894A
Authority: US
Inventors: Rudolf Hess; Heinz Engel
Original assignee: Akzona Inc
Current assignee: Akzona Inc
Priority date: 1969-10-27
Filing date: 1970-10-26
Publication date: 1972-08-01
Anticipated expiration: 1989-08-01
Also published as: LU61848A1; GB1267893A; CH504553A; BE754695A; ES382827A1; FR2066694A5; NL7012101A; AT311219B; DE6941966U

Abstract

In combination with means to transport a continuous mono- or multi-filament thread in a linear thread path at a controlled rate of withdrawal, a frictional false twist device consisting of a single freely rotatable roller positioned obliquely to the linear thread path to receive a spiral loop of thread therearound, the freely rotatable roller having a concave arcuate thread contacting surface which is a surface of revolution.

Description

United States Patent Hess et a1.

[ 51 Aug. 1,1972

[54] FALSE TWISTING APPARATUS [72] Inventors: Rudolf Hess, Elsenfeld; Heinz Engel, Kelsterbach/Main, both of Germany [73] Assignee: Akzona Incorporated, Asheville,

22] Filed: Oct. 26, 1970 21 Appl. No.: 83,894

[30] Foreign Application Priority Data Oct. 29, 1969 Germany ..G 69 41 966.5

[52] US. Cl. ..57/34 HS, 57/77.3, 57/77.4 [51] Int. Cl. ..D02g l/04 [58] Field of Search..57/34 R, 34 HS, 51, 51.6, 77.3, 57/77.4, 156, 157

[56] References Cited UNITED STATES PATENTS 2,410,419 11/1946 Bellezza ..57/77.4

2,718,111 9/1955 Brown ..57/77.4 3,026,668 3/1962 Latimer ..57/77.4 3,470,583 10/1969 Denyes et al ..57/77.3 X 3,559,391 2/1971 Rice ..57/77.4 X

Primary Examiner-Donald E. Watkins Attorney-Johnston, Root, OKeefe, Keil, Thompson & Shurtleff 5 7] ABSTRACT In combination with means to transport a continuous monoor multi-filament thread in a linear thread path at a controlled rate of withdrawal, a frictional false twist device consisting of a single freely rotatable roller positioned obliquely to the linear thread path to receive a spiral loop of thread therearound, the freely rotatable roller having a concave arcuate thread contacting surface which is a surface of revolution.

10 Claims, 4 Drawing Figures FALSE TWISTING APPARATUS To crimp man-made monofilamentsor man-made continuous multifilament yarns as defined in the German Industrial Standards, DIN 60001 (September, 1964), page 4, paragraph No. 2, it is common practice to subject them to a false-twisting treatment, i.e., to pass them over or through a heater and then through a cooling or fixing zone to a false-twisting means and finally to a take-up spool. The twist producedby the.

falsetwisting means is carried back against the direction of thread travel through the heating means up to a twist-stopper. In this way, the largely plasticized or softened filament or multifilament thread passing the heater has the opportunity to twist and, as it passes through the cooling zone between the heater and the false-twister, the twist is fixed in it. Twisting back to the zero point, i.e., zero-twist, is achieved by the rotation of the filament or' thread as it passes the twisting unit, usually by means of a so-called twist-trapper. Accordingly, the filament thus treated and then collected or wound on a take-up spool does not have a genuine twist, but merely a tendency to rotate when it is off-,

wound and relaxed.

Typical false-twist devices for imparting a durable torque-crimp to threads or yarns of a fibrous synthetic thermoplastic polymer are disclosed in a detailed explanation of the torque-crimp process set forth in Woven Stretch and Textured Fabrics by Hathome, John Wiley & Sons 1964), Chapter 2. Attention is also directed to US. Pat. No. 2,803,109 for this description" of the originally developed false-twist process.

In this very widely adopted texturizing process, it is further known-that a continuous monofilament or continuous multifilament thread or yarn can be permitted to travel over a twisting means including a rotatable roller arranged obliquely to the direction in whichthe thread or yarn is traveling, cf., German Utility Model No. 1,898,540 and US. Pat. No. 2,946,181. The principle on which so-called friction false-twisters" of this kind are based is that the filaments running obliquely onto the surface of the twister (which is generally positively driven although in some cases it may be freely rotatable), show a tendency to wander from their position relative to the twister, but are rolled back into their original position both by the tension inherent in the filament or thread and also by the friction between filament and twister. Known rollers for such frictional twistersare in the form of truncated cones (US. Pat. No. 2,946,181) or cylinders (German Utility Model No. 1,898,540). The disadvantage of cylinders is that several rollers arranged parallel to or perpendicularly of one another are usually required for guiding the filaments in a satisfactory manner. These known falsetwist devices in which the monofilament or thread is looped at least partly around the twister, are unable to operate without yarn or thread guides before and/or after the twisters. Another disadvantage of these known twisters resides in the twist slippage which occurs in contrast to more conventional false-twist spindles, e.g., small tubes equipped with a twist-trapping pin, a'ndthe false-twisting is subject to wide fluctuations. Hitherto, it has only been possible to reduce these fluctuations by arranging several rollers one behind the other.

One, object of the present invention is to provide a frictional false-twist device which does not exhibit any of the disadvantages of conventional false-twisters, i.e., uncontrollable slip, the need to provide several identical rollers and/or the need for yarn guides. A further object of the invention is to provide a false-twist device which makes it possible to work at much higher takeoff rates than was possible with conventional twisters of the frictional type referred to above, especially in drawtwist apparatus employing a false-twister. Take-off rates of more than 800 m/min. are now possible, being accompanied by stretching, whereas previous take-off rates were limited to about 400 m/min. Another object of the inventionis to provide a false-twist device which has a sufficiently high static friction even though looping is not much in excess of 360, i.e., using approximately one turn or spiral loop around the false-twister.

These and other objects and advantages of the invention will become more apparent upon consideration of the following detailed disclosure.

It has now been found, in accordance with the invention, that especially useful and advantageous results I can be achieved in a false-twist apparatus for the treatment of a continuous monofilament or multifilament thread, especially for texturizing the thread with a heatset durable torque crimp, by employing apparatus which comprises means to transport the thread in a substantially linear path including means for withdrawing the thread from a feed source at a constant rate, and a frictional false-twist device consisting of a single freely rotatable roller arranged with its axis of rotation obliquely to the linear thread path in order to receive a thread contact surface is preferably an arcuate surface mounting the roller on ball bearings, roller bearings or the like such that it can be easily turned by a filament or thread looped around the roller under tension and taken off at a constant speed, i.e., at a constant winding or withdrawal speed. In other words, the roller must be rotated by the thread without having to be positively driven by an auxiliary motor or other positive drive means.

. The false-twist device-employed in the apparatus of the invention consists of only a single roller because by virtue of the geometry of this roller, there is no need for one or more auxiliary rollers, thread guides or other means for improving the false-twisting action and guiding of the thread.

The term thread contact surface is employed herein to designate that part of the roller circumferential surface which comes into contact with the transported monofilament or continuous multifilament thread through looping approximately once'around the roller. According to the invention,it is this yarn contact surface which is concave with a smooth curved or arcuate shapeand represents a surface of revolution, i.e., a

the yarn contact surface of the roller is a surface of revolution generated by rotation of an are symmetrical with respect to the centerline perpendicular of the axis of rotation of the roller, about the axis of rotation, is particularly easy to manufacture and at the same time particularly suitable for uniformly texturizing monofilaments and continuous multifilament threads or yarns- To obtain especially uniform friction conditions between the filament or thread and the thread contact surface, it is of advantage for this contact surface to be roughened to a depth (R,) of from about 2 to 8 microns (cf. German Industrial Standards, DIN 4762, Sheet 1). The yarn contact surface is preferably given a hard dull chrome finish for the same reasons.

The invention is also described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 is a largely schematic view of draw-twist apparatus illustrating the path followed by the thread as it islooped around a twister according to the invention;

FIG. 2 is a longitudinal section through a false-twist roller according to the invention together with its mounting for free rotation on a fixed spindle.

FIGS. 3 and 4 are plan views of two difierently mounted false-twist devices according to the invention in which the thread contact angle, i.e., the oblique angle between the thread and the false-twist roller is made variable by adjustably arranging and fixing the spindle in different positions.

In FIG. .1, the roller 1 acting as the false-twist device is arranged between a heated fixing pin '14 and a stretching godet with its adjacent guide roller 15a of an otherwise conventional draw-twisting machine. Betweenthe fixing pin 14 and the roller 1, there must be a sufficiently longcooling zone to ensure a heatsetting or fixing time suitable for the withdrawal rate of the false-twistedfilament or thread 16. The path followed by the filament or thread extends from the delivery spool or bobbin 12, over the guide pin 13, partly around the fixing pin 14, once around the roller 1 and then with several loops around the stretching godet assembly 15 and 15a, as shown by a continuous a heating plate, an elongated heating tube providing a contact and/or radiant heater or the like.

A number of variations can be made in the specific draw-twist apparatus shown in FIG. 1 provided that one retains the essential freely rotatable false-twist roller 1 with its correct position in a linear transported path between feed means and withdrawal means. For example, the supply package or bobbin 12 can be of any conventional form and one can employ a set of feed rolls to more carefully control the rate of feed as well as inserting various types of tensioning means as the thread is brought into a linear path leading to the false-twist roller. Likewise, other withdrawal means may be employed although the godet and guide roller assembly has been found to be especially advantageous. In order to achieve a uniformly false-twisted filament or thread, it is desirable to maintain av substantially constant tension and a substantially constant linear velocity of the thread as it is withdrawn in its linear path interrupted only by the loop around the false-twist roller.

It is a particularadvantage of the invention that the single freely rotatable roller does not require supplemental guides, rollers, motor-driven spindles, twisttrappers or similar elements in order to function properly as a false-twist device. This means that the thread can be transported directly from the heating means or other feed point at which the backed up twist is stopped up to the false-twist roller, and likewise that the thread can than be conducted directly to the withdrawal means, The term directly is used here in I the sense that the thread is conducted in a substantially broken line. Instead of the heated fixing pin 14, it is linear free path without any contact with other threading elements such as guides, rollers or the like.

FIG. 2 provides details of one preferred embodiment of the frictional false-twist roller according to the invention. The roller V1 with its arcuate concave thread contact surface is mounted on roller bearings 7 so as to be freely rotatable on a spindle 2. A bushing 3 and rings 6 and 8 prevent the roller from being axially displaced. Discs 4 and 5 are designed to prevent dirt from getting into the bearings. The roller 1 shown in FIG. 2 has a concave yarn contact surface 9 which is in the form of a surface of revolution generated by the rotation of an are about the axis of rotation ll,"this are which is also identified by 9 being symmetrical with respect to a perpendicular line 10 passing through the center of the axis of rotation 11 of the roller 1.

FIG. 3 illustratesa false-twist roller with a variable or adjustable contact angle. Coming from the heating plate as in FIG. 1, a thread 16 passes the roller 1 and at the same time'is looped about once around it and then, while being false-twisted, continues traveling to the stretching godet and guide roller assembly. (The remaining apparatus has been omitted since it either corresponds to FIG. 1 or may include other conventional apparatus such as a take-up spool or the like.) Similarly to the arrangement shown in FIG. 2, the roller 1 is mounted for free rotationby means of roller hearings on a fixed spindle attached to an L-shaped support 17. The leg 17a of this support 17 is spaced backwardly from the roller 1 and is pivotally mounted for rotation to a supporting plate or frame 19 at the center of rotation 18 by means of a suitable locking screw. At the free end of the roller support 17,- there are reference marks 21 which indicates the thread delivery, the angle of contact can be easily measured with a conventional protractor or other tool.

The device according to the invention is particularly suitable for texturizing monofilaments and continuous threads having only two or three individual filaments.

Polyamide threads, i.e., nylon threads, having a denier or size of dtex l4f2, dtex 22f l, dtex 22f2 and dtex 22 f 3, have been successfully false-twisted and tests with deniers of dtex 50 have also been successfully conducted as have tests with other fibrous polymers, for

example polyesters such as polyethylene terephthalate. (The total yarn size is measured as dtex" preceding I -the value given while f precedes the number of individual filaments in the thread.)

The false-twist roller of the invention in combination with other conventional thread transporting apparatus and especially in a so-called draw-twist or stretch-twist machine permits very high speed operation with a corresponding improvement in production capacity. The false-twist roller itself is light in weight and easily constructed so that it will rotate freely at high speeds in frictional contact with the running thread. With a relatively long free path of the thread both before and after the false-twist roller, there are no other parts or thread contacting elements which can interfere with the smooth and trouble-free operation of the single roller. Moreover, the rotational velocity of the roller according to the invention is self-regulating and there is a minimum of thread slippage or loss of twisting so that very uniformly texturized filaments or threads can be obtained when processing preferred synthetic thermoplastic fibrous polymer filaments in an otherwise conventional manner.

The invention is herebyclaimed as follows: 1. F alse-twist apparatus for the threatment of a continuous monofilament or multifilament thread composed of a linear fibrous high molecular weight polymer which apparatus comprises:

means to transport said thread in a substantially linear path including means to withdraw said thread from a feed source at a controlled rate; and

' a frictional false-twist device consisting of a single freely rotatable roller arranged with its axis of rotation obliquely to said linear thread path in order to receive said thread in a single spiral loop therearound, said freely rotatable roller having a concave thread contact surface which is a surface of revolution.

2. False-twist apparatus as claimed in claim 1 wherein said concave thread contact surface of said freely rotatable roller is an arcuate surface symmetrical with respect to a plane perpendicular to the roller axis of rotation at the center of said roller axis.

3. False-twist apparatus as claimed in claim 1 wherein the thread contact surface is roughened to a de th f about2to8microns.

alse-twist apparatus as claimed in claim 1 wherein aid thread contact surface has a hard dull chrome finish.

5. False-twist apparatus as claimed in claim 2 whereinthe thread contact surface is roughened to a depth of about 2 to 8 microns andhas a hard dull chrome finish.

6. False-twist apparatus as claimed in claim 1 wherein said thread withdrawal means is a stretching godet and guide roller assembly arranged to receive said thread directly from said freely rotatable roller.

7. False-twist apparatus as claimed in claim 1 including heating means for heating said thread as it is transported in said linear thread path leading up to said freely rotatable roller, said heating means being separated from said freely rotatable roller'by a distance sufficient to permit cooling of the thread and fixation of the twist wherein said heating means is arranged to transport the thread directly therefrom in said linear path to said freely rotatable roller and said thread withdrawal means is arranged to receive said thread directly in said linear path from said freely rotatable roller.

10. False-twist apparatus as claimed in claim 9 wherein said thread withdrawal means is a stretching godet and guide roller assembly.

W105 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION v 7 Patent No. 1680 502 Dated v mag mg J I 1912 Inv'entor(a) Hess et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5; line 45 "threatment" should read treatment .1

Signed and sealed this 12th day'of-Deoember 1972.

(SEAL) Attest:

EDWARD'M.FLETCHER,JR. ROBERT GOTTTSCHALK Attestlng Officer Commissioner of Patents

Claims

1. False-twist apparatus for the threatment of a continuous monofilament or multifilament thread composed of a linear fibrous high molecular weight polymer, which apparatus comprises: means to transport said thread in a substantially linear path including means to withdraw said thread from a feed source at a controlled rate; and a frictional false-twist device consisting of a single freely rotatable roller arranged with its axis of rotation obliquely to said linear thread path in order to receive said thread in a single spiral loop therearound, said freely rotatable roller having a concave thread contact surface which is a surface of revolution.

3. False-twist apparatus as claimed in claim 1 wherein the thread contact surface is roughened to a depth of about 2 to 8 microns.

4. False-twist apparatus as claimed in claim 1 wherein aid thread contact surface has a hard dull chrome finish.

5. False-twist apparatus as claimed in claim 2 wherein the thread contact surface is roughened to a depth of about 2 to 8 microns and has a hard dull chrome finish.

7. False-twist apparatus as claimed in claim 1 including heating means for heating said thread as it is transported in said linear thread path leading up to said freely rotatable roller, said heating means being separated from said freely rotatable roller by a distance sufficient to permit cooling of the thread and fixation of the twist imparted thereto.

8. False-twist apparatus as claimed in claim 7 wherein said heating means is a heated pin at the beginning of said linear thread path leading up to said freely rotatable roller.

9. False-twist apparatus as claimed in claim 7 wherein said heating means is arranged to transport the thread directly therefrom in said linear path to said freely rotatable roller and said thread withdrawal means is arranged to receive said thread directly in said linear path from said freely rotatable roller.