US2754071A

US2754071A - Thread tensioning device

Info

Publication number: US2754071A
Application number: US160604A
Authority: US
Inventors: Furst Stefan; Beckers Hans
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-08-03
Filing date: 1950-05-08
Publication date: 1956-07-10
Anticipated expiration: 1973-07-10
Also published as: DE893321C; GB697329A; NL79851C; CH292368A; BE498477A; FR1026209A

Description

y 1956 s. FURST ET AL THREAD TENSIONING DEVICE] Filed May 8, 1950 3 mm B \2 w w p H F A 4 A 2 2 2 3 0 2 F p 4 2 a 1 \w W b mm Z 2 .4 g

2,754,071 THREAD TENSIONING DEVICE Stefan Fiirst and Hans Beckers, M. Gladbach, Germany, assignors to Walter Reiners, Waldneil, Lower Rhine, Germany Application May 8, 1950, Serial No. 160,604 Claims priority, application Germany August 3, 1949 4 Claims. (Cl. 242154) The present invention relates to thread tensioning devices provided with a plurality of wrapping elements of the so-called claw-brake type, through which the thread must pass, and which by each wrapping action increase the tension in the thread.

The orderly operation of tensioning devices of this kind is not interfered with by dust. But it is well known that the thread tension produced by devices of this known type is a very irregular one and, for that reason, frequently causes breaking of the thread. The irregularity of the thread tension is due to the fact that the increase in tension produced in the tensioning device is merely a multiple of the tension existing in the thread where the latter enters the tensioning device, although, as is likewise well known to the art, the entering tension may vary between 0.5 and 5 gram when the thread is moving at high speed.

According to the laws of rope friction, the tension of a thread pulled over a body at rest increases in value at the same rate as the angle of wrap formed by the thread as the body increases in size and in proportion to the amount of friction existing between the thread and its support. But the irregularities of variations in the tension of the thread are not changed by the tensioning in any way, and that is why in tensioning devices of the known kind the variations in tension at the outlet side of the tensioning device are the same as at the thread inlet side. If, for instance, the tension of the thread at the inlet side of the device is between 0.5 to 5 gram and is to be increased tenfold in the device, then the tension,

at the outlet side of the device will be between 5 to 50 gram. It is obvious that a tensioning result of this kind is completely unsatisfactory, as in most cases a tension of 5 gram will not suflice to produce a suificiently hard coil or cop, while a tension of 50 gram will usually result in breakage of the thread.

In many cases, the variations in tension are further increased by the fact that the movable part of the claw brake begins to perform oscillatory movements, whereby the differences in tension are augmented instead of being smoothed down. It has been tried to provide the adjustable moveable part of the tensioning device with damping means in order to prevent periodically occurring tension shocks from causing the aforesaid oscillatory movements. But this has merely reduced the additional movements of the movable part of the tensioning device and at the outlet as at the inlet side.

The present invention is in the first place based on the conception that an improvement of the claw brakes will be attained if the weight of their movable parts is reduced to such an extent that they respond to every reduced to the same degree as the inlet tension has increased.

irregularity frequencies transmitted by the thread to the tensioning means, so that an incitement to self-oscillation the pressure means is thereby rebe sure, the pressure means of the To provide the magnetic field of force, either one of a plurality of electro-magnets may be employed in such a way that the force of the magnetic flux can be simultaneously and uniformly adjusted for a plurality of tensioning devices.

The pressure or tensioning members may be rotatably arranged in the device for the performance, either singly or in groups independently of each other, of swinging movements in the direction toward the thread.

In summary, in devices according to the invention the movable parts of the thread-brakes are subjected to an external force through magnets, which counteracts the of the thread increases, the the thread decreases accordingly and vice versa. ing in value or size are the inlet tension and the wrap and vice versa.

The invention will be more fully understood from the following description in conjunction with the explanatory diagrams and embodiments shown on the drawing in which:

Fig. 1 is a diagrammatic illustration of the thread tensioning means, showing how a thread passing through them is forming small angles of wrap at the tensioning members;

Fig. 2 is a diagrammatic illustration of the same thread tensioning means, showing how a thread passing through them is forming large angles of wrap at the tensioning members;

Fig. 3 is a coordinate diagram of transverse pressure versus angle of wrap;

Fig. 4 is a longitudinal section of a tensioning device with tensioning members capable of swinging movements independently of one another;

Fig. 5 is a cross-section on line V-V of Fig. 4;

Fig. 6 is a diagrammatic illustration of a plurality of the tensioning devices of Figs. 4 and provided with simultaneously adjustable current supply means.

Referring now to the drawings in detail, the reference character F denotes a thread passing between stationary tensioning members 1 and movable tensioning members 2 of a tensioning device. As illustrated in Figs. 1 and 2, the thread F is pulled through the tensioning members 1 and 2 in the direction of the arrow 3. There is a certain entering or inlet tension in the thread at'the side Where the portion 4 of the thread enters the tensioning device, and there also is a certaih outgoing or outlet tension in the thread at the side where it leaves the device in the direction of the'arro'w 3. The angles of wrap formed by the thread at the tensioning members 1 and 2 are indicated at 5. The tensioning pressure exerted upon the ovable tensioning members is etfective in the direction of the arrow 6.

In Fig. 3 the entries on the horizontal line 7 represent the sum of all angles of wrap, While on the vertical line the transverse pressures in gram are entered. Curve 9 indicates the dependence of the two values upon each other.

In the embodiment shown in Figs. 4 and 5, a plurality of pin-shaped pressure or tensioning members 18 are arranged in the casing 1 7 of a tensioning device. The pressure members 18 are resting against stationary supports provided by the coils of a wire helix 19 secured in casing 17 with the aid of a clamping pin 20. Positioned beneath the casing of the tensioning device is a magnet 21composed of elongated magnet bars 22 below the casing of the tensioning device. The magnetic flux between the magnet bars 22 and the pressure members 18 is schematically indicated by lines 23. The magnet 21 carries a magnet coil 24.

According to Fig. 6, a group of tensioning devices 25 of the type illustrated in Figs. 4 and 5 is provided with a common current supply line 26 for all magnet coils 24. The current supply line 26 is energized by a source of current 27 whose current supply or voltage is adjusted by means of a regulator 28.

The operation of the illustrated devices is as follows:

When the thread is being pulled through a thread tensioning device with stationary tensioning members 1 and movable tensioning members 2 as illustrated in Figs. land 2, a wrapping of the thread F partly around the movable tensioning claws 2 and partly around the stationary tensioning claws 1 is forcibly eifecte'd by the movable claws 2.' The size of the angle of Wrap 5 depends on the position of the movable claws 2 with" respect to the stationary claws 1. The deeper the movable claws 2 are forced between the stationary claws 1, the larger is the angle of wrap.

If the outlet tension of the thread at the arrow 3 is to be constant in spite of varying inlet tensions in the portion 4 of the thread, then the angle of wrap 5 at the tensioning members must vary with every variation in inlet tehsion,"a's" according to the lawsof rope friction the tension of the'thread increases or decreases "when the angle of wrap 5 increases or decreases. In order to obtain angles 'of wrap WhihQregardless of the varying inlet tension of the thread, produce a constant outlet tension, the movable tensioning members 2 have to be placed under variable pressures 6 of very definite magnitude iii conformity with the characteristic indicated in Fig. 3. This illustration shows that when the'angle of wrap is small, the transverse pressure must likewise be small, and when the angle of wrap is large, the trans verse pressure must likewise be large. This is so because the occurrence of a small angle of wra'p is due to the fact that the inlet tension in portion 4 of the thread is already high enough to require only slight additional tensioning for which only small transverse pressures are needed (see Fig.1), Under the conditions of Fig. 2, however, the inlet tension in the thread portion 4 5 :2. small. Hence, in this case large angles of Wrap and correspondingly large transverse pressures are needed to produce at the arrow 3 an outlet tension corresponding to the outlet tension of the thread of Fig. 1.

In the thread tensioning device illustrated in Figs. 4 and 5, the just-mentioned performance is obtained as follows: the movable pins 18 of comparatively light weight are biased by the attractive force of magnet 2i so as to exert pressure on the thread F passing under neath the pins 18 but above the turns of the stationary member 19. The movable pins change their position with respect to the stationary member in conformity with the change of inlet tension occurring in the thread portion 4. As a result, the pressure exerted upon the movable pins increases at the same rate as the distance through which the pins are moving. This rate is in conformity with the rate of increase of the angle of wrap. The weight of the pins is so slight that, when the irregularities or variations in thread tension stay within normal limits, the change in position of the movable pins is so rapid as to instantly follow every change in inlet tension, thus securing the desired constancy of outlet tension.

When according to Figs. 4 and 5, pressure is exerted upon the thread F by a plurality of tensioning members 18 independently capable of swinging movement toward the thread F, the pressure members 18 can readily be given an especially high natural frequency. By virtue of the independence of their respective swinging movements, such members reliably prevent the occurrence of joint oscillations of equal size and frequency. A thread tensioning device of this type is particularly suited for thread motion of the very highest speed. The remarkable capability of tension-responsive reaction of the pressure members 18 is secured by the action of the electromagnet 21. The magnetic flux 23 from the magnet bars 22 imposes a constant attractive force upon the pressure members 18 acting as magnet armatures. This magnetic force increases in proper proportion to the extent of downward movement of the pressure members 18 between the stationary supports 19. Hence, the aboveexplained relationship between transverse pressure and angle of wrap also applies to this embodiment.

Instead of employing electro-magnets it is also possible to use permanent magnets to achieve the desired result.

If electromagnets are provided, the density of the magnetic flux in a plurality of tensioning devices 25 may be regulated simultaneously by controlling the current in the current supply line 26 by means of the regulator 28, as illustrated in Fig. 6. Such a control circuit makes it possible to adjust the outlet tension simultaneously and uniformly for a group of thread tensioning devices.

While'I have described my invention with reference to particular embodiments, it will be understood that the various parts maybe changed or modified without departure from the spirit of the invention and may be embodied in devices other than those specifically set forth, all within the scope of the appended claims.

What I claim asnew and desire to secure by Letters Patent of the United States:

i 1. A device for tensioning a length-wise moving thread comprising a plurality of fixed members in spaced alignment along the thread path, a plurality of movable magnetizable members substantially devoid of operative inertia spaced in alternation with said fixed members, said fixed and movable members being adapted to tension said thread by frictional contact therewith as the thread is drawn past and alternately about said fixed and movable members in a partial wrap about each, and a magnet urging said movable members with a variable force transversely of said thread path to increase the angle of each said partial wrap, said force increasing as, said movable members move 'in a direction to result'in a greater degree of wrap and decreasing as they move in the opposite direction.

2. A device for tensioning a travelling thread, comprising a multiplicity of mutually spaced stationary tenbers respectively disposed between each two of said stationary members and being yieldingly displaceable in a direction transverse to the alignment yond said alignment for causing the thread to form at each stationary area an angle of wrap variable in depend ence upon the position of said respective movable members, said movable members being magnetizable and being individually disposed in the field of said magnet for tension-responsive movement toward and away from said magnet whereby said magnet imposes upon said movable members a variable biasing force in said direction and substantially proportional to the variations in the tension of the thread at said movable members, said movable members having a natural oscillation frequency higher than the frequency range of the variations in thread tension, whereby the variations in thread tension cause displacement of said movable members in opposition to said force to vary said angles in the tension equalizing sense.

3. In a device according to claim 1, said stationary members being disposed below the thread path, said magnetizable movable members consisting of respective pins movable independently of one another and extending transversely of the thread path to rest upon the thread when the device is in operation, and said magnet being stationarily disposed beneath the thread path.

4. In combination, a plurality of thread tensioning devices according to claim 2, each device having said stationary members disposed below the thread path and having said magnetizable movable members consisting of respective pins individually movable and extending transversely of the thread path to rest upon the thread when the device is in operation, said magnet being an electromagnet disposed beneath the thread path, said electromagnets having respective energizing coils, and an electric energizing circuit connected with said coils and having a current control member for adjusting the intensity of said magnet fields to simultaneously adjust said devices.

References Cited in the file of this patent UNITED STATES PATENTS 1,303,320 Houghton May 13, 1919 1,375,568 Cunnitf Apr. 19, 1921 1,399,521 Rodger Dec. 6, 1921 1,516,885 Houghton Nov. 25, 1924 1,602,447 Olson Oct. 12, 1926 2,005,975 Javery et a1. June 25, 1935 2,104,809 ODowd Jan. 11, 1938 2,202,323 Sullivan May 28, 1940 2,223,912 Guenther Dec. 3, 1940 2,223,923 Sinness Dec. 3, 1940 2,283,767 Schoenenberg May 19, 1942 2,326,714 Wholton Aug. 10, 1943 2,343,535 Clarkson Mar. 17, 1944 2,393,243 Franz Jan. 22, 1946 2,478,926 Kingsbury Aug. 16, 1949 FOREIGN PATENTS 528,386 Great Britain Oct. 29, 1940