US2667313A

US2667313A - Tension device

Info

Publication number: US2667313A
Application number: US41580A
Authority: US
Inventors: Norman E Klein
Original assignee: Milliken Research Corp
Current assignee: Milliken Research Corp
Priority date: 1948-07-30
Filing date: 1948-07-30
Publication date: 1954-01-26
Anticipated expiration: 1971-01-26

Description

6, 1954 N. E. KLEIN 2,667,313

TENSION DEVICE Filed July 50, 1948 2 Shegts-Shoet 1 INVENTOR NORMAN E. KLEIN Jan. 26, 1954 N. E. KLEIN 2,667,313 TENSION DEVICE Filed July so, 1948 2 Sheets-Sheet 2 INVENTOR NORMAN E. KLEIN Patented Jan. 26, 1954 TENSION DEVICE Norman E. Klein,

Deering Milliken N. Y., a nonprofit trust Application July 30, 1948, Serial N0. 41,580

21 Claims.

The present invention relates to devices for introducing tension into filamentary material, such as yarn, and comprises a novel device of this character which may be advantageously employed with untwisted filamentary material, hereinafter called zero twist yarn, as well as with yarn of low or of high twist. The new device is simple of construction, is quick to respond to variations in yarn tension and insures even distribution of tension in the filaments of the yarn strand.

Various tensioning devices have heretofore been suggested and used but none of the prior art devices has been entirely satisfactory, particularly when used to introduce tension into zero or low twist yarn. Among the known devices are those wherein the yarn is drawn between rotatable disks which are spring biased into engagement. Other known devices are those wherein the yarn is caused to travel over fixed curved surfaces, such as pins, which act as tension amplifiers. In both such types of devices the tension introduced into the yarn is due to the friction between the yarn and the surface over which it moves. These devices, because of the relative movement of the yarn with respect to a surface, tend to roughen the yarn and are unsatisfactory. They result in excessive damage to the outer filaments of the yarn with consequent retardation of broken ends of such filaments relative to the body of the yarn. Particularly in connection with twisting devices, where yarn must be under relatively high tension while traveling at a rapid rate, there has been a need for a positive acting tension device that does not have the disadvantages inherent in the prior art devices.

The primary object of the invention is, therefore, to provide a tension device suitable for use with yarn of any degree of twist, including zero twist.

Another object of the invention is to provide a yarn tension device which is readily ad ustable over a relatively wide range of applied tension.

Still another object of the invention is to provide a device of the above described character in which there is an even distribution of tension in the filaments of the yarn strand.

A further object of the invention is to provide a tension device for yarn in which the tension introduced by the device is automatically varied in response to variations in input tension of the yarn and in a direction to maintain substantially constant tension.

Other objects of the invention will become apparent as the description proceeds.

Various tension devices embodying the inven- Stamford, Conn., assignor to Research Trust, New York,

tion are illustrated in the accompanying drawings of which; 7

Figs. 1 and 2 are side and front views, respectively, of a simple tension device embodying the invention and particularly suitable for use in quilling operations;

Figs. 3 and 4 are side and front views, respectively, of a yarn tension device of the general type of that of Figs. 1 and 2 but provided with means automatically responsive to a function of the outflow path of the yarn for varying the tension introduced by the device;

Figs. 5 and 6 are diagrams representing other constructions of tension devices of the type of Figs. 1 and 2;

Figs. 7 and 8 are diagrams representing other constructions of tension control devices of the general type of that of Figs. 3 and 4; and

Figs. 9 and 10 are side and top plan views, respectively, of a tension device representing still another embodiment of the invention.

In each of the illustrative embodiments of the invention hereinafter to be described, one of a pair of nip rollers is yieldingly urged against a brake. The yarn or other filamentary material passes between the rollers and in the preferred embodiments of the invention contacts the surface of each through a substantial angle so as to prevent relative slippage between the yarn and either roller. The frictional resistance offered by the brake to rotation of the rollers by the yarn introduces a corresponding tension into the yarn. In the preferred embodiments ofthe invention the yarn is so threaded through the device that the tangential pull of the yarn on one or the other of the rollers tends to decrease the pressure between the braking surface and the braked roller with increase in back tension of the yarn. Thus a preferred tension device introduces a tension into the yarn which is maximum when the input yarn tension is a, minimum and which decreases as the input tension increases. By adjustment of the spring or other biasing means, the tension added by each device may be varied. Such adjustment may be effected manually, nection with the embodiments of the invention illustrated in Figs. 3, 7 and 8, such adjustment may be made automatically in response to a func tion of the outflow path of the yarn.

In the specific tension device of Figs. 1 and 2, to which reference may now be had, the nip rollers are indicated at 2 and 4. The axle 6 of roller 2 is journaled in lugs 8 extending from a support frame I0. The axle I2 of roller 4 is journaled in the ends of a pair of arms I4, which are supported at their other ends by a pin l6. The

or, as hereinafter described in conmatic compensation for input tension variations is provided, but manual adjustment only of the H]. The frame l0, adjacent the roller 4, has a bias pressure between roller and brake is shown. re-entrant section 28 intermediate shoulders 22. Hence, for any specific adjustment of the bias The spring l8, through the arms M, yieldingly pressure, the device tends to maintain constant urges the roller 4 =into-contactwiththe roller 2 output-:tension.r-,By the: construction-illustrated and into Contact with the shoulders 22 of the in Fi 3 and uto which-refer n e-m y n w b frame. Adjustable screw means 24, carried by bad, automatic adjustment of the bias pressure the frame and engaging the spring 18 provides -.'-.in response to a function of the angle of take the means for adjustment of the pressure be-/ off of the yarn fr m e tfl w guide is tween th roller 4 a d braking s rfa 22, --tained. Such automatic adjustment of the bias Inflow a d tfl w guides for th yarn .may b -pressure between.the-.braked roller and the brakmounted directly on the frameyas indicated at-zt ssu fac is qftpa ti ular valu w e ya and 28, or may form parts of any standard de- 1 uponiemergence' from the tension device, is free vice with which the tension unit is associated. 1 1031110011, 218 in w n Operation. as it p pin I6 is journaled in one end of a leaf spring 18, the other end of which is secured to the frame The yarn, indicated by A, after 'passagethrough the inflow guide 26, makes a half turn about the roller 4, on the side ofethe roller adjacent the frame l0, passes through the nipsof therollers and then contacts roller 2 through substantially 90 in. transit-to theoutfiowguide 28. The reentrant. section '20. provides clearance .for .the yarn. in passing around .therroller 4. so that there is no frictional engagement of the yarn with any fixed surface .in its .trayelbetween the guides. The pivotal mounting of the. arms M on the spring L8 permits the roller 4 to be-swung away from-the frame It! for ready threading of the de- .vice. Both

rollers

2 and 4 may bemade of rubber, or rubber surfaced, but preferably roller 4 is of relatively hard, wear-resisting, material such as nylon or steel. The .shouldersZZ of the frame, providing the braking surfaces for roller 5, may be formed of anymaterialhaving a suitably .high coefiicient of friction with respect to the material of the roller. 1 It will be. apparent from the above description :that the tension device of Figs. v1 and 2 functions as hereinbefore described. ;The leaf spring l8 urges the-rollers 2 and 4qinto contact: and also urges .the roller 4 into contact with the-braking surfaces .22. ,Ifthe yarn A as it; approaches roller :4 is.under ndappreciableback tension, the pressure; between the roller 4 andythe braking surfaces, and hence the frictional drag on the roller 4 will be constant when the rollers are rotated by the yarn; When there is back tension in the yarn, a component of force is createdtending to lift theroller 4- from the braking surface. This reduces the frictional-drag onthe roller 4 with corresponding:;reduction in the tension intro- .duced-bythe tension device; By adjustment of screw-.means-:24,'the pressure between the roller and'braking surfaces dueto the spring l8 may be: varied over a relatively wide range. As the yarn in its travel-between the guides and 28 has v no sliding contact withany. surface; damage to thefilaments thereof is avoided. The guides themselvesneed. offer but slight frictional resistance-to the yarnfiow. They'may-be shaped to provide:only a: small angle ofr contact with'the yarn tandhence tension added thereby will .be a minimum. -Iher'pressurerzbetween the'rollers 2 and' tinsures even distribution of tension among the filaments of theyarnstrand.

The tension devicecf Figs. 1 and 2 may be advantageously employed wherever tension isto be introduced-into travelinglfilamentary material. For example, the device may housed in coning, quilling; spooling or other winding'operation and also in twisting and doubling operations It is particularly useful with yarn of low or'zero twist and in'operations where the yarn travels at relatively high speeds.

arm the tension device' of Figs; 1 and 2 auto= ""vides automatic compensation for changes in the larger. of the two, is preferably of rubben'or is rubber surfaced; "whileroller 4a is preferably a hard surfaced roller. .The axle 6a of roller 2a is journalled in bearings in-arms 8a integral with the support frame Illa of the device. The frame lila is'provided'with a pairof spaced braking surfaces 22a for. engagement with the surface of roller 4a. A. lever arm. 30' is 'pivotally mounted at one end on the frame tfia and' carries at its other end a yarn outflow guide 2801.. The inflow guide comprises an eyelet'28a carried by the frame Illa. Axsmall rod'or pint! of sapphire-or the like wear-resisting material is mounted in the eyelet 25a transversely of the inlet passage for passage of the yarn'thereover; When'the yarn is drawn'off over the end ofasupply package and passed directly to the tension device, the pin resolves the rotational motionof 'the yarn'into reciprocatory motionand 'hence' causes the yarn O to transverse the roller 4a; spreading the wear thereof. The axle lZa' of roller da is journalled in the ends of apair of arms I la of sheet-spring material which are interconnected at their other ends by a cross member 32 which spans arm' 3% near the outflow guide 28a and is pivotally mounted thereon'by means of a pivot'pin '34. A compression spring l8apengaging a stud 35 carried on arm 30 and a fixed part 3% on the frame intends torock the arm 30 about'its pivot on the frame in a direction to urge the roller lav against the surfaces 22a and against the roller 2a. Pressure between the rollers isalso provided by the bowed spring arms Ma. The stud 36 is. mounted on a screw 39 to permit of manual adjustmentof the" compression of the spring lea and consequently of the bias pressure between the roller wand brake surfaces 22a.

In the particular embodiment of'the invention illustrated in Figs. 3 and 4, the outflow guide 28a. is'rotatably mounted in the arm 35, as by ballbearings (not shownh-and has a yarn passage 48 therein, the extended axis of which is substantially tangent to the surface of roller 2a. Passage. All. gradually increases in cross: section in the direction; ofyarn. travel. The surface of the guide at the.outlet.end.of .the passage is rounded, and smooth, preferably-polished; for minimizing friction. between the yarn and guide when the yarnis drawn ofi-at an angle to the axis. of the'passage.

. The path of the yarn A through the device of Figs. 3 and 4 is the same as through the device of Figs. 1 and 2,namely', from the inflowguide 26a, around and incontact with the roller 4a on the sidethereof adjacent vthe vbrakingxsurfaces, around and in contact with roller 2a through an arc of substantially 90 and then to the passage 4fl-of the outflow guide 28a. The direction of the path of the yarn beyond the outflow guide and, therefore, the length of contact of the yarn with the rounded surface of the guide depends, of course, upon the location, relative to that of the tension device, of the particu lar yarn takeup mechanism with which the tension device is associated. Such take-up mechanism may include a moving element, such, for example, as used for traverse of a yarn package, or the moving element may be a rotating fiyer interposed in the yarn path between the tension device and take-up mechanism. N take-up mechanism is indicated in the drawing as such mechanisms are well known, and so far as the functioning of the device of Figs. 3 and 4 is concerned, it is immaterial what type of mechanism is assumed as the cause of travel of the yarn through the tension device. If the direction of flow of the yarn from the outflow guide to the take-up mechanism is at a substantial angle to the axis Of the passage 40, for example if the outflow direction makes an angle a. with the axis of passage 40, as indicated in Fig. 3, there will be a component of force acting through the guide on arm 30 in a direction tending to counteract the compression in the spring, and, therefore, tending to reduce the pressure between the roller 4a and braking surfaces 2 2a. If the angle a of take-off of the yarn with respect to the axis of the passage 40 decreases so that the yarn contacts the surface of the guide 28a through a smaller angle, the component of force opposing the action of spring I80. decreases. Conversely, with a change of take-off angle'that increases the angle of contact of yarn with the guide surface, the. component of force opposing the action of spring 18a increases. Thus the maximum tension introduced by the device is automatically decreased as the angle of contact of the yarn with the outflow guide increases. This feature of the device of Figs. 3 and 4 provides compensation, at least in part, for the fact that tension introduced by the friction between the yarn and the surface of the outflow guide increases exponentially with the angle of contact of the yarn with the surface.

The relation between the magnitude of the component of force tending to decrease the pressure between roller and braking surfaces and the angle of take-ofl? of the yarn is P,,=T (1e cos a) where Py is the component of resultant force acting downwardly on the guide, T1 is the tension in the yarn at entrance to the passage 40, is is the coefficient of friction between the material of the guide and the yarn and a is the angular change of direction of the yarn at the guide. When f is of the order of 0.2, the rate of change of P with 0. reaches a maximum when a. is approximately 113. Thus when the yarn is drawn from the guide 28a at approximately that angle, maximum sensitivity of the tension device to change of direction of outflow of the yarn is obtained.

To derive Formula I it is only necessary to find the component parallel to the axis of passage 4!) of the resultant of the tensions in the yarn, before and after leaving the guide. As the tension beyond the guide, T2, is equal to expressions for the resultant force and for the desired component are readily obtained. It will be *understood that the control level, that is, the bias pressure F5, for any particular setting of the biasing means, will be equal to KP where K is a constant determined by the configuration or geometry of the parts of the device.

Two embodiments of the invention have now been described, one in which the tension introduced by the device is varied in response to back tension in the yarn, and the other in which there is an additional response to angle of take-off of the yarn. In each device the resilient means biasing a roller against a braking surface has been shown as an adjustable spring. In Fig. 5 is diagrammatically illustrated a tension device embodying the invention in which magnetic means instead of spring means is employed to provide the bias necessary for braking.

In Fig. 5, 42 represents a horse shoe type magnet having hook-shaped pole face extensions 44, of which only one appears in the view shown in the drawing. The braked roller 51) is formed of rubber or the like and is mounted on an iron shaft [2b which serves as the armature of the magnet. A frame "lb of brass, aluminum or other nonmagnetic material supports the roller 21) and the outflow guide 28b and has brakin surfaces 221) engaged by the roller 4b. The attraction of the pole face extensions 44 for the shaft [212 causes the roller 4b to be pressed against the braking surfaces 22b and against the roller 2b. As the attraction of a magnet for its armature is a force acting, when the armature is withdrawn, to return the armature to attracted in that respect a resilient the device of Fig. 5, the roller resiliently biased against the against roller 21). Suitable inflow guide means may be mounted within the arms of the magnet 42, as indicated in dotted lines at Zi'ib. As in the tension devices of Figs. 1 and 3, the yarn A passes from the guide 26b, around, and in contact with, the roller 4b on the side. engaging the braking surfaces 221), then between the rollers, around, and in engagement with, the roller 2b for a quarter turn and finally to the outflow guide 28b.

The pole face extensions 44 are preferably mounted for adjustment toward and away from the shaft l2b so as to permit of adjustment, as by the slot and screw indicated at 24b, of the maximum pressure between roller 4b and the braking surfaces 221). The operation of the device of Fig. 5, being the same in all respects as that of Figs. 1 and 2, needs no further description. The free mounting of theroller 4b of Fig. 5 eliminates the necessity of providing bearings for its shaft and likewise simplifies the threading of the device as will be readily apparent.

In the tension devices so far described, the mechanical advantage (ratio) between the yarn and braking forces is unity. The slope of the curve representing the relation between the tension, T0, at input to the rollers and the tension T1 at output therefrom, for any given bias pressure, F5, between the braking surface and the braked roller, depends only upon the coefficient of friction fb between the materials of the roller and of the braking surface. Expressed mathematically this relationis f I force and hence in 4b may be said to be braking surface and Thus, theoretically, completecompensation for variations in input tension with the devices so position, it is,-

accmis far :descrihed'is :;obtained't only. when jais equal of fb, the slope of the characteristic curve of the device of Fig. 6 will be less than thatof do vices having a one-to-one ratio. In the particular device of Fig. 6 there is approximately a twoto-one ratio between the yarn and braking forces and hence the coeflicient of friction between the braking surface and braked roll is effectively doubled.

In the device shown in Fig. 6, the nip rollers, indicated at and 4c, areofequal diameter. Roller 26, which is preferably the hard surfaced roller, is the braked roller. It is rotatably mounted in lugs 80 which extend downwardly from an upper side of an open framework 100. Roller 40, which is preferably of'rubber, is carried on the end of an arcuate arm Me which also carries brake shoes 220 for engagement with v the roller 20. The arm Me is pivotally mounted at on an arm 46 which, in turn, is pivotally suspended from an upper side of the frame W0. A tension spring lBc is secured at one end to arm 5% and at its other end to a nut 58 threaded on a screw 240. The. screw frameand provides the. means for adjustment of the tension of spring I80. The frame [00 is provided with substantially aligned inflow. and outflow guide passages indicated at 26c and 28c. respectively, and a traversing pin '3! is provided in the inlet guide passage, as described in con nection with the device of Figs. 3 and 4. In the particular construction of device illustrated in Fig; 6, the axes of the nip rollers are in substantially the same horizontal plane whereas the pivotal axis 45 of the arcuate arm [40 on arm it is above this plane. Hence, under the tension of spring I80, the force acting at the axis of roller do has a vertical component, which, in the absence of the brake shoe, would cause the roller ie to ride up on the roller 2c. This vertical component thus provides the bias pressure between brake shoe. and roller 2c whereas the horizontal component provides the pressure between the rollers.

The yarn path through the'device is from the inlet guide 260, around and in contact with the roller ie, between the nips of the rollers and then around, and in contact with, the roller 20 on the side engaged by the brake shoes 22c and thence to the outlet guide 280, the yarn, in this embodiment engaging the surface of each roller through substantially 180. Back tension in the yarn acts downwardly on roller ie and hence tends to reduce the braking pressure on the roll 20. The mechanical advantage between the yarn and braking forces is the ratio of the respective radii from the pivot to the axis of roller 40 and to the point of braking; calling this ratio R, the slope of the charatceristic curve of the device is r 24a is carried by the 8 which, when R equals 2.; reduces .to zero for fb=0.5.

Thus, the construction of Fig. 6, as compared to that of Fig. 1, for example, will result in more nearly complete compensation for changes'of input tension when using similar friction surfaces or, for equal compensation, permits the use of materials of lower coefficient of friction.

In the construction of Fig. 6 there is substantially wrap of the yarn about each of the rollers. This is advantageous as it insures nonslipping contact of the yarn with the rollers and permits the force transmitting roller, in this instance, the roller 20, to be of hard wear-resisting material.

Another construction of a device of the general type of that of Figs. 3 and 4 is diagrammatically indicated in Fig. 7, to which reference may now be had. In this embodiment of the invention, the axle 1211 of the braked roller M is mounted in arms Md which are pivotally mounted on the base or frame 10d while the cooperating niproller id is rotatably carried by a movable member 52 which also carries the output guide 2201. Member 52 is pivotally mounted on the frame Hid, as indicated at 54, and is biased by a compression spring ltd in a direction to apply pressure between the rollers and between roller 4d and braking surfaces 2201 on a block 56 secured to the base led. The yarn A, upon leaving the inlet guide, whichmay comprise a passage 26d in the frame [0d, passes around, and in contact with, the roller 2d, then between the hips of the rollers, around and in contact with the roller 4d on the side thereof in engagement with the braking surfaces and to the outlet guide 28d. 'As the outlet guide 2803 is carried by the biased element 52, the device will be sensitive to the angle of outflow of the yam as is the device of Figs. 3 and 4. Manual adjustment of the maximum pressure between roller Ed and the braking surfaces 220! can be effected by adjustment of the compression of spring 18d as in the embodiments of the invention heretofore described.

In Fig. 8 as illustrated another embodiment of the inventionwherein there is automatic adjust ment of the device in response to a function of the outflow path. Thedevice includes an E- shaped frame i9c,.the'1ower leg of which may include the inlet guide 286, the middle le of which provides the braking surfaces for the roller ie and the upper frame of which rotatably supports parts now to be described. A tubular member 58, which is rotatably mounted in ball bearings 5? in the upper leg of the frame lfle, has

a disk 62 secured thereto above the frame, and.

a cam 64 secured thereto below the frame. A generally conical member 66 is secured to the upper end of member 58, or is formed integral therewith. Pivotally supported on the middle leg of the frame we is a curved arm t8 Which carries at its free end a follower Hi for the cam E l. Arm 63 has a leaf spring H secured thereto which is engaged by a screw 12 threaded through the frame we. The action of spring ll providessufiicient pressure between follower it and cam 65 to insure continued contact therebetween and to provide frictional resistance to rotation of the cam and the parts associated therewith; A sec ond leaf spring 74 secured to arm 58 provides resilient mounting for. the braked roller se, the axle of the roller beingjournaled inarms Hie which are secured at their other endsto the spring I4. The axle*of;-the cooperating roller 2c is iournaled in arms 16 pivotally mounted on the frame near the base of the upper leg and held in engagement with a fixed stop Tl by means of a spring 79.

With the above described arrangement, the yarn A passes from the inlet guide ZBe, contacts the surface of roller 26 through an arc of more than 180, passes between the rollers, then around and in contact with roller 4e on the side adjacent the braking surfaces on the middle leg of the frame and then up through the tubular member 58. When the yarn is drawn off from the device in a downwardly direction, as indicated, to an element so moving as to cause the yarn to balloon about the tension device, it will engage the edge of disk 62. If the balloon tends to contract, due to increase in tension of the yarn, the friction between the yarn and disk will tend to rotate the disk in the direction of rotation of the balloon and in opposition to the frictional resistance to rotation offered by the pressure exerted on the cam by its follower. When the output tension in the yarn is sufiicient to move the disk and cam about the axis of member 58, the cam, acting through the follower, rocks the arm 68 about its pivot on the frame in a direction to reduce the pressure between the roller 6e and the braking surfaces. This reduces the tension introduced by the device and consequently also the output tension in the yarn. As inthe other embodiments of the invention, increase in input tension in the yarn also tends to reduce the braking pressure. The screw 12 provides means for manually adjusting the maximum pressure between braking surfaces and roller 46. The device of Fig. 8 may be readily threaded by swinging roller 2e into the position illustrated in dotted lines on the drawing. It will be understood that the end of the middle leg of the frame Hle will be cut away beneath the central part of roller 4e to provide clearance for the yarn in its passage around that roller.

A tension device particularly adapted for use with an incremental twister is illustrated in Figs. 9 and 10. In this embodiment of the invention the axes of the nip rollers 21 and ti are journaled in a pair of spaced arms 78 which are interconnected and pivotally mounted on the frame or platform It) by means of a pin 80. The arms 78 are preferably of sheet spring material and intermediate the bearings for the axles of the rollers 2) and 41 have U-shaped loops 82 therein providing compression spring action urging the rollers into engagement. The section interconnecting the arm '18 above the frame is provided With an upstanding flange 84 to which is secured one end of a compression spring I81. The other end of spring [8] engages a shoulder 86 on a shaft 88 which is screw threadedly mounted'in a vertical support 90 and lockedthereto by a nut 92. A knurled head 93 on the end of the shaft serves for adjustment of the pressure exerted by the compression spring [8f on the flange 84. Support 90, which is secured, as by screws 94, to any suitable fixed part of the particular yarn handling mechanism with which the device is to be associated, 'is preferably formed integral with the frame l0).

An inlet passage 26f in the platform I (If beneath the rollers serves as a guide for the yarn, A and the yarn travels upwardly through the passage 26f and between the rollers 21 and 4 At least one, and preferably both, rollers 6 and 8 are made of rubber or are rubber coated so that the yarn will be gripped firmly but will not be bruised.

Roller 4f normally engages the platform "If, as shown in Fig. 9 and is pressed against the platform by the compression of the spring [8) tending to rotate the arms 18 about the pin in a counterclockwise direction.

In the operation of the device of Figs. 9 and 10, the rollers which rip the yarn firmly therebetween under the action of the spring metal loops 82, are rotated by the yarn as it is drawn up through the device, roller 4 oifering'resi'stance to rotation due to the friction between that roller and the platform I 0f. Increase in yarn tension tends 'to rock the arms "against the biasing action of spring 18] and thus reduces the frictional resistanceto rotation ,of the roller 4,. Spring I8 is adjusted so that, when the tension in the yarn is thatdesired, roller 4f has but slight frictional engagement with platform I01. Adjustment of the compression of spring 181 is readily efiected by rotation of knurled head 93 of shaft 88. l

The invention has now been described with reference to seven different embodiments thereof in each of which tension is introduced into travelling filamentary material or yarn by frictional drag opposing rotation by the yarn of one of a pair of nip rollers. In each of the preferred embodiments of the invention increase in back tension of the yarn reduces the pressure between the braked roller and the braking surface providing the frictional drag on the roller. In each embodiment of the invention resilient adjustable means are provided for biasing the braked roller into engagement with the braking surface and in certain of the embodiments of the invention automatic adjustment of the bias pressure in response to a function of the outflow yarn path is provided. In each case the yarn is gripped firmly at the hips of the rollers and tension introduced by the frictional drag involves no sliding contact of the yarn with a fixed surface and hence relatively high tension may be introduced into fine yarns of low or zero twist without damage thereto. As heretofore indicated, the nip rollers may be of the same or of different diameter, both may be of relatively elastic material or one may be hard surfaced.

The following is claimed:

1. A tension device for traveling filamentary material which comprises a member having a frictional surface, a first rotatable element having a cylindrical surface in engagement with said frictional surface and reciprocally movable relative thereto to change the frictional dragonsaid element, a second rotatable element having a cylindrical surface in frictional engagement with the cylindrical surface of said first element, whereby both elements are adapted to berotated by passage of filamentary material therebetween and whereby when the direction of travel of material during such passage is away from said frictional surface such passage can apply a force upon said first element to tend to remove it from engagement with said frictional surface, and resilient means urging said first element into engagement with said frictional surface.

2. The tension device according to claim 1 inincluding inflow and outflow guide means for the material positioned with respect to said rotatable elements to provide a generally S-shaped path for the material in passing between said rotatable elements thereby insuring driving engagement i 4 ll 7 r V of'the material with each rotatable element over a substantial angle, s

3. The'ten'sion device according'to claim lin'cluding a'n'output' guide fcrthe material and means cooperating therewith; tending to vary the pressurebetw'een'said frictional surfacefand' said first element in accordance with the relation P-,,"=T1('1-'e "cosa) where PU is the component of force acting'on the guide in a direction to'decrease'the pressure between saidvfrict'ional surface and first element, Tris the tension in the material at entrance to said guide'f is the oeflicient of friction between theinate'fial and the guide and a is the angular change ih-iiirectibnof the material at said guide.

4. 'A tensicn device for travelihg'filai'nntary maven-a1 comprisin in Combination, a pair bf flip rbueiisaaapteu tobe rotated by trave1 or filanentaiy material therebetw'een', a member having' a surface positioned 'in engagement with the cyinaneai surface of one of said rollers to apply a frictional drag thereto, support means for said rollers providing pivotal movement therebetween including resilient means for biasing said last in entionedroll'er and said member surface into frictional engagement, and-guide means for the material positioned; relative to said rollers and to'sai d'inembersurfa-ce to'le'ad material to the direction away from said surface whereby tension in the material-acts in opposition to said resilient means to reduce-the pressure between saidlast r'nentioned roller and iiieniber-s'urface;

5. T *ten'si'on' wherein-said silpp'ort means forsaid rollers comprises "a fixed with respect to said member surface and 'rotatablysupporting' one-of said rollers, and an armlinkedte'said part and relof said rollers in a atively m vable with respect thereto, "said arm 5 supporting the other of said rollers and said biasing means operating through said arm to urge said last mentioned roller into engagement with said i member surface.

6.'The tension device according 'to "-claiin 4 wherein said guide means are positioned with respectto said rotatable elements to provide a circuitouspath 'for the material in passing T between said rotatable elements thereby insuring driving engagement relief over a substantial angle-.

lffh e tension device according to claim 4 wherein said supper t'means for said rollers comprises a fiiced part supporting one e'f said'rel'lers "and a movable part supporting said member and the "other roller, *said biasing means *opera'ting through said movable part to urge s'aidmember surface into engagement with the I roller 1 su pp'orte'd-on the fixed part and to urge said rollers into engagement; 7

8. The tension deviceac'cording to claim-' 4 ineluding means for adjusting said biasing means tovary .the maximum pressure between said member surface and said roller.

9. The tension device according to claim i wherein said guide means includes an outflow guide and wherein there is providedmea-ns associated with said outflow guide and responsive to a function of the angle of outflow of the material therefrom for automaticallyadjusti-ng said biasing means.

10. The tension device according to claim 4 including means associated with said guide rotational motion of the means resolving any material at infiow to the device into reciprocadevice according 'toclaim- '4 or the 'material" with each i torymotian substantially parallel to the axes of the rollers whereby whe'n materialis delivered to the device with rotational motion, the material will traverse the rollers with limited back and forth motion axially thereof during passage through the devic'e.

11. A tension device for traveling filamentary material which comprises a member having a frictional surface, a first rotatable element in engagement with said surface, a second rotatable element in frictional engagement with said! first element whereby both'are adapted to 'be retated'bypassage of filamentary material therebetween, pivotally connected support means for saidelements'and said member permitting relative movement between the surface and said first element, resilient means biasing said first element and surface-into engagement, and guide means for the material positioned to insurea substantial angle of contact ofthe' material with each'eleme'nt whereby the longitudinal pull of the material on one elementacts in opposition to said resilient means to'red-uce the pressure between said surface and said first element, the rateof change of the output tension T1 in the material with change of "input tension To being substantially equal to where is is the coefiicient of friction between the surface and said first element and R is the ratio of the respective distances tothe pivotal point of connection of the support means of the point of applicationof the tangential pullof thematerial on one eleme'nt and of the point of application of the frictional drag of said surface on the first elernen't.

1-2. The tension device according to claim '11 wherein the tangential pull of the material acts on'the first element whereby R is substantially equal to unity.

13. The tension device according'to claim 11 wherein the tangential pull of the material acts on said-second element and wherein said second element is carried on said support means at a distance from the pivotal point of connection of the support means greater than thatof the point of application- 0f the f-rictionaldrag of said surface on the first element from the pivotal point whereby R is greater than unity.

14. A tension device for traveling filamentary material comprising a pair of nip rollers adaptedto be" rotated by passage of filamentary ma"- terial therebetween, inflow and outflow guide means for the material so positioned relative "to saidrollers as to insure contact 'of'the material with each roller over an are'ofsubstantialiy 9.0, a brake member positioned for frictional engage-.- ment with one 'of'said rollers, support meansfor .esaid: rollers *and said brake member 7 including two relatively-movable *parts :of' which one is: fixed relatively to said inflow guide means; one of said parts supportingsaid brake-member and one of said rollers andthe-otherof said parts supporting the other roller, and resilient means interconnecting said parts andrbiasing t brake member carried by one-part into engagement with the roller carried by the otherzparaithe tangential pull ofthe'material'on oneofsaid rollers tending to reduce the braking pressure, whereby the device tends to compensate ior variations in bacl; tension of the material.

15. The tensiondevice according to claim 14 wherein the brake memberi's carriedby the movable part of said support and such part includes a link pivotally mounted at one end on the fixed part of the support means and an arm pivotally connected to said link, the roller being carried by said arm at a greater distance from the pivotal point of connection with said link than is the brake member whereby back tension in the material acting on the roller not in engagement with the brake member tends to move said brake memher out of contact with the other roller.

16. A tension device comprising in combination a pair of spaced guides, a pair of nip rollers positioned between said guides, a structure having a surface positioned for engagement with one of said rollers, means biasing said last mentioned roller against said surface, and means supporting said one roller for relative movement with respect to said structure and to provide passage of filamentary material in transit between said guides and between said nip rollers with a substantial angle of contact with said biased roller on the side facing said surface so that tension in the material tends to reduce the pressure between said biased roller and said surface.

17. A tension device for traveling filamentary material comprising in combination, a pair of nip rollers adapted to be rotated by filamentary material traveling therebetween, support means for said rollers comprising two parts pivotally coupled together, one of said parts having a braking surface positioned for engagement with one of said rollers, said last mentioned roller being carried by the other of said parts, and resilient means associated with said support means for biasing said last mentioned roller into engagement with said surface, whereby when filamentary material travels between said rollers and contacts the surface of the biased roller over a substantial are on the side thereof adjacent said braking surface, tension in the material tends to move said roller away from said surface, and outflow guide means operatively coupled with said resilient means to vary the biasing pressure between said last mentioned roller and said surface in response to a function of the tension in the material beyond said outflow guide means.

18. A tension device comprising a frame, brake surfaces on said frame, a first roller having an axle journaled in said frame, a spring strip secured at an end to said frame, a member pivotally coupled to the other end of said strip and a second roller rotatably supported by said member with its surface in engagement with said brake surface and with said first roller, said spring acting through said support members to apply pressure between the rollers and between said second roller and the brake surfaces on said frames.

19. A tension device for filamentary material comprising in combination a frame, additive ten- 6 sion means carried thereby, said frame having a passage therein of generally circular cross-section for leading filamentary material to said means, and a rod engageable by material and extending transversely of said passage for resolving any rotation motion of material at inflow to the device into reciprocatory motion axially of said rod to impart limited traversing movement to said material as it passes through said means.

20. A tension device for traveling filamentary material which comprises a member having a frictional surface, a first filament guide roller having a cylindrical frictional surface adapted to engage the first named frictional surface, means to mount the member and first roller to permit relative movement of the frictional surfaces toward and away from each other, means to urge the frictional surfaces into engagement yieldingly, a second filament guide roller, means to mount the second guide roller with its filament guide surface in rolling contact with the filament guide surface of the first roller inflow guide means on one side of said filament guide rollers, and output guide means on the opposite side of said filament guide rollers, said rollers being arranged with respect to said member so that when filamentary material travels between said rollers and contacts the frictional surface of said first roller over a substantial are on the side thereof adjacent the frictional surface of said member, tension in the material tends to move said first roller away from said member surface.

21. A tension device for traveling filamentary material comprising a support, input and output guides disposed in spaced relation on said support and through which said material is adapted to be drawn, a pair of rollers positioned between said guides on said support and yieldingly supported for relative movement both radially and circumferentially of each other, said material in traveling through said device being passed between said rollers and wrapped therearound in opposite directions over a substantial arc of at least one of said rollers, a brake member positioned for engagement with said one of said rollers, and means biasing said rollers into engagement with each other and said one of said rollers into engagement with said brake member, the tension in said material acting to oppose said biasing means to cause said one of said rollers to be urged circumferentially of said other roller and in a direction away from said brake member.

NORMAN E. KLEIN.

References Cited the file of this patent UNITED STATES PATENTS Number Name Date 387,396 Cleghorn Aug. 7, 1888 568,621 Martin Sept. 29, 1896 578,099 Hanson Mar. 2, 1897 2,320,264 Chapman May 25, 1943 2,348,856 Selvig May 16, 1944 2,362,920 Moore Nov. 14, 1944