US2949723A

US2949723A - Apparatus for curling thermoplastic threads

Info

Publication number: US2949723A
Application number: US721281A
Authority: US
Inventors: Schrenk Hans Alwin; Pieter Van Dijk; Heijnis James Watt Ijsbrand
Original assignee: American Enka Corp
Current assignee: Akzona Inc
Priority date: 1957-03-18
Filing date: 1958-03-13
Publication date: 1960-08-23
Anticipated expiration: 1977-08-23

Description

Aug- 23, 1960 H. A. SCHRENK ETAL 2,949,723

APPARATUS FOR CURLING THERMOPLASTIC THREADS Filed March 13. 1958 7 47 i \IIW v0.1 49 M W 9 A. 1

INVENTORS v HANS ALWIN SCHRENK PIETER VAN DIJK JAMES WATT IJSBRAND HEIJNIS BY i ATTORNEY 2,949,723 Patented Aug. 23,- 1960 APPARATUS FGR CUREENG THERMOPLASTIC THREADS Hans Alwin Schrenk, Arnhem, Pieter van Dijk, Velp,

and .lames Watt ljsbrand Heijnis, Arnhem, Netherlands, assignors to American Enlra Corporation, Erika, Nil a corporation of Delaware Filed Mar. 13, 1958, Ser. No. 721,281 Claims priority, application Netherlands Mar. 18, 1957 Claims. (Cl. 57-34) This application is a continuation-in-part of application Serial No. 657,844, filed May 8, 1957, now Patent No. 2,855,750. in that application, a false twisting apparatus including a high speed spindle is described for use in combination with a source of thread supply, a twist stop, a thread heater, a cooling zone, and a thread discharge device in the curling of thermoplastic threads. The false-twisting spindle more particularly comprises a rotatably mounted tubular spindle which is pressed by means of a driving belt into two or more throats, each formed by a number of discs which are freely rotatable around different shafts, at least one of the disc rims cooperating with a peripheral groove in the spindle. As described in column 6- of the above-identified patent, it is preferred that only two pair of discs, each pair form ing one throat, be utilized for supporting the false-twisting spindle. The shafts of the discs are mounted on a base plate which is transversely movable with respect to the driving belt. A locking mechanism is provided which in the operative position of the spindle does not touch the latter but in the withdrawn position of the base plate keeps the spindle with its peripheral groove in contact with a disc rim.

With the apparatus described, it is possible to curl thermoplastic threads operating at a velocity of up to 60 m./min., since the false-twisting device may be rotated as fast as 180,600 revolutions per minute.

in operation, it has been found that certain problems are involved in applying a sufficient amount of heat to a thread running at these relatively high velocities to fix the twist imparted by the false twist device.

it is an object of this invention to provide an improved apparatus for curling thermoplastic threads.

Another object is to provide such an apparatus having an improved thread heater device associated therewith.

Still another object is to provide an apparatus for curling thermoplastic threads which has improved operational features.

A further object of the present invention is to provide a unitary heater and false-twisting spindle assembly which may easily and quickly be shifted and held either in operative or inoperative position of the spindle.

Other objects will be apparent from the following detailed description when taken in conjunction with the accompanying drawing which shows in perspective one embodiment of the present invention.

In general, the apparatus of the present invention is characterized by having a tubular heating element with a maximum inner diameter of 0.8 mm. The tubular heating element is connected to a pivotally mounted base plate coaxial with the false twist spindle. Improved means are also provided for bringing the false twist spindle into driving relation with the driving belt.

Upon mounting the tubular heating member on the base plate in the indicated position, it was found that during normal use of the device the thread obtains a vibrating movement between the thread guide mounted in front of the heating device and the false-twisting device. In this way, a maximum heat transfer is obtained from the wall of the small heating tube to the thread. This makes it possible to achieve a thorough heating of the twisted thread with small heating tubes of a relatively short length. Such intensive heating is essential for obtaining a thread with optimum curling properties.

The mounting of the small heating tube on the base plate makes it necessary to connect the small tube to a source of energy in a movable manner. In order to keep this connection as simple as possible, it is preferred in those cases where the heating device is mounted above the false-twisting device to suspend the base plate swingably and to hold it in the operative position with the aid of a hook. This hook may serve to press the false-twisting spindle more forcibly or less forcibly against the belt driving system, as desired.

in this embodiment of the invention, the hook may operate in connection with an arm one end of which is rotatable around a shaft fixed parallel to the axis of swinging of the base plate on the frame of the machine. The hook portion comprises a tensioning pin extending from said arm in a direction parallel to the axis of rotation thereof, the tensioning pin being adapted to move over a running-on cam provided on the base plate. Moveent of this pin over the cam serves to urge the movable base plate toward the driving belt.

To prevent the swingably mounted base plate from moving out of the non-operative position to the operative position under the influence of gravity as a result of which the false-twisting spindle would start to rotate at an undesired time, a spring may be provided which tends to resist the swinging movement of the base plate into the operative position.

It may be desired to cool the thread with the aid of a small cooling tube having an inner diameter of not more than 0.8 mm. after heating but before passing through the false-twisting device. If so, the cooling tube may preferably also be fixed to the base plate and disposed coaxially with respect to the false-twisting spindle in its operative position.

The invention will be further elucidated by reference to the accompanying drawing showing in perspective an embodiment of the device according to the invention.

In the drawing reference numeral 10 denotes generally a false-twisting device comprising a tubular spindle 11 provided with an elongated peripheral groove 12, represented here as a reduced diameter portion, extending longitudinally of the spindle from immediately above the uppermost supporting disc to immediately below the lowermost disc. For details on the dual operation of this groove as a running or supporting surface and also as a means for preventing axial displacement during operation of the spindle, see the aforesaid US. Patent No. 2,855,750.

On the under side of the tubular spindle 11 3. diametrically extending bracket 13 has been formed in the under side of which a perforated sapphire thread guide 14 has been clamped.

Driving belt 15 exercises a pressure against the spindle 11 when the false-twisting device is in the operative position. This driving belt, of which only a portion is shown, is actuated by any suitable driving mechanism (not shown). The belt 15 is pressed against the spindle 11 by means of guiding rollers 16 of which only one is shown in the drawing. The pressure exercised by the driving belt 15 keeps the spindle 11 at the upper rim and at the lower rim of the groove 12 in contact with the rims 17 of a couple of discs 18, these n'ms consisting of a wear resistant rubber. Discs 18 are fixedly arranged with two others in pairs on, shafts 19 which. are rotatably.

3 mounted balltrear-iri-gs The dism 18 of each pair are arranged at such a distance from each other that in the operative position of the spindle 11 all discs are in contact with the peripheral groove 12 therein.

The roller bearings 20 are fixed in a base plate generally indicated 22. Said base plate 22' consists" oftwo parts, a horizontal part 34 and a vertical: part 35. A column 23 is connected to" the horizontal part 34 of the base plate 22. A'pair ofhooks 24 are fixed to the'column 23. These hooks do not touch the spindle 11 when it is in the operative position. However, on bringing the false-twisting device out of the operative position, at which time the belt pressure is removed, hooks 24 catch the spindle 11 before the elastic rims 17 come out of the peripheral groove on the spindle. Anopening 25 is provided in'the part 34 of the base plate to permit passage th'erethrough of the threadbeing processed.

The vertical part of the base plate 22 is providedwith a pair oftenons- 36 which test in jaws 37 formed in the free ends of arms 38. The arms 38 are fixed to the frame (not shown) of the machine by means of a supporting rod 39. This makes it possible to pivot the unitary assembly comprising the base plate 22- and the vertical part 35 around the horizontal axis defined by tenons 36. When this movement occurs, spindle 11 is moved toward or away from driving engagement with belt 15. y

A running-on cam 26 is attached to the plate 35 by any suitable means anda limiting pin 27 extends from said cam 26. A tensioning: pin 28, adaptedto cooperate with the can 25, extends sideways from a tensioning hook 29. The hook-29, whichis at one end provided with a jaw 38, is at the other end rotatable around a shaft 31 connected to the frame of the machine.

The shaft 31 is further provided with a block-shaped support32 to which a spring 33 is connected. The length of the spring 33 is such that when tensioning book 29 is in the position shown in the drawing the spring is tensioned. W p

Onthe vertical part 35 of the base plate a strip 41 of insulating material, such as asbestos board, is fixed. In

the upper end of this strip there is a bore 42 in which a.

small block 4.3 is arranged inn-freely shiftable position. Between the bottom of the bore 42 and the block 43 a sprin 44 is provided, which spring iritbe position shown is somewhatcompresscd and the'reforeeirercises an upwardly directed force on the small block 43 A cross-arm 45 extends from the small block 4-3, the arm consisting of a material which may conduct electric due rent. A second cross-arm 46 consisting of a similar material extends from the lower side of the strip 41 of ihsulating material.

The cross-arms 45 and 46 are connected to a small metal tube 47 foi'ine'd from resistance material and with an inner diame'tei" of 0.6 aiida wall thickness of 0.2

- mm. current reed wires 48 and 49 are linked up with the

arms

45 and 46. p

By the "ction' off the: spring 44 the small tube 47 is kept in a stretched condition. The sman tube 47 is surrounded by a mantle 50 to prevent as much cooling of the small tube aspes'sibte. Mantle 50 may be constructed of any suitable material such phenol-formaldehyde type plastic. A thread guide 51 is mounted above the entrance of the small tube 47 for guiding a thread before entering the small tube. A second thread guide 52 hired to the column 23 serves to guide thethread after leaving the false-twisting devise. Both thread guides 51 and 52 are coaxially mounted with the small heating tube 47 and the spindle 11 when the latter is in operative position. In order to be able tofi use the above-described device for curling thermoplastic threads '21 bobbin holder, a thread supplying device and a twist stop (not shown) should be mounted abc'ive the thread guide 51- iri a known manner. Below the thread guide 52 there should further be provideda thread discharge device. In said cu'rlir'ig device the thread supplying device and the twist stop may, if desired, comprise a pair of clamping rollers connected with a driving mechanism. By such a combination the twist formed by the false-twisting device is prevented from running back farther than to the clamping point of the rollers. A positively driven roller may be used as the thread discharge device.

To operate the device a bobbin with the thread to be curled is placed on the bobbin holder and the beginning of the thread is guided between the clamping rollers through the thread guide 51, the small heating tube 47, and the opening 25 to the false-twisting device 10. The thread is pulled first through the central bore of the spindle 11 and then with one winding around the lower part of the mantle of the sapphire 14. The thread is then passed through the thread guide 52 and via the thread discharge device to a winding device. As soon as the small heating tube has reached the required temperature and the apparatus is brought into motion, the curling process starts.

For curling a 30 denier thread of polycaprolactam-having 10 filaments at a speed of 40 m./min., the belt 15 is driven at a velocity of 38 m./se'c. Consequently the falsetwisting spindle 11 having a diameter of 4.5 mm. is

' rotated at 160,000 r.p.m.- A preferred diameter of the discs is 40 mm. A heating tube having a length of 35 cm. at a temperature of to C. is used, an air path of 25 cm. being maintained between said tube and the false-twisting device. heating tube is not more than about 0.8 mm.

For deactivating the false-twisting device 10, for instance in case of thread rupture, the tensioning book 29 is lifted so far that the running-on cam 26 can move underneath the tensioning pin 28. As a result of this the spring 33 may move the base plate 22 forward so that the spindle 11 comes free from the driving belt 15 and comes to a stop. The spring 33 is so dimensioned that it is released before the tensioning pin 28 comes free from the cam 26. In this manner shifting of base plate 22 into an inoperative position is facilitated,

In order to prevent the untimely swinging-through of the base plate in the direction of the driving belt 15 the limiting pin 27 may be brought into the jaw 30 of the tensioning book 29.

The tensioning hook 29 is lifted in order to bring the spindle 11 into contact with the belt 15. Due to this, the running-on cam 26 may pass underneath the tensionirig pin 28 after which the base plate 22 may swing in the direction of the driving belt 15 until this movement is stopped by the spring 33. When lowering the tensioning hook 29 the tensioning pin 28 contacts the running-on cam 26 and presses the same on further movement downward of the tensionifig hook together with the base plate 22 and the spindle 11 in the direction of the belt 15. This movement of the tensioning book 29 is limited by the limiting pin 27.

In order to prevent an upward movement of the tensioning book 29 during the curling operation, the lower part of the running-on cam 26 has a curve the center of which is coaxial with shaft 31. The curve of the upper part of the cam 26', however, is more pronounced than that of the lower part so that the loosening of the tensioning hook 29 over the upper part of the cam may be facilitated.

While moving the base plate 22 to and from the operative position, it will be apparent that there is no change in the relative position of the small heating tube 47 and the false-twisting spindle 11. The correct position of the small heating tube 47 relative to the false-twisting spindle is therefore always maintained. This position is fixed when constructing the machine for obtaining an optimum heating of the thread passing therethrough.

Various modifications of this invention will be apparent to those working in this field. It is therefore intended that the scope of the invention will be measured by the following claims.

The inside diameter of the What is claimed is:

1. A device for curling thread comprising a tubular member adapted for rotation. and having at least two running surfaces from which the same is supported, at least two pair of discs rotatable about spaced axes and having peripheral surfaces adapted to cooperate with said running surfaces to support said tubular member for rotation, drive means for imparting rotation to said tubular member, a tubular heating element disposed coaxially with respect to said tubular member in its operative position, a base plate mounting said supporting discs and said tubular heating element in spaced relationship, and means permitting pivotal movement of said base plate toward and away from said driving means.

-2. A device for curling thread as set forth in claim 1 wherein the tubular heating element has an inner diameter of not more than about 0.8 mm.

3. A device for curling thread as set forth in claim 2 wherein the base plate is pivotally hung and is provided with cam means for guiding the same into operative or inoperative position.

4. A device for curling thread as set forth in claim 3 provided with a tensioning pin carried on a tensioning hook mounted for pivotal movement about a shaft, said tensioning pin being adapted to move over the surface of said cam means so as to guide said base plate toward or away from said driving means.

5. A device for curling thread as set forth in claim 4 wherein spring means are provided to resist the movement of said base plate into operative position as said tensioning pin is moved over the surface of said cam means.

References Cited in the file of this patent UNITED STATES PATENTS 2,557,104 Hegediis June 19, 1951 2,791,086 Hilbert et a1. May 7, 1957 2,813,393 Kingsbm'y et a1. Nov. 19, 1957 2,829,487 Stoddard et a1 Apr. 8, 1958 2,837,889 Comer June 10, 1958 FOREIGN PATENTS 276,601 Switzerland Oct. 16, 1951 651,337 Great Britain Oct. 31, 1947 674,122 Great Britain June 18, 1952