US2661913A - Damping means for yarn tension compensating devices - Google Patents

Description

Dec. 8, 1953 E. HElzER Erm..

DAMPING MEANS FOR YARN TENSI ON COMPENSATING DEVICES Filed June 24. 1952 "lil INVENTORS EaQz/ardJ/eizer By Jofz Warwick ATYREY Patented Dec. 8, 1 953 DAMPING MEANS FOR YARN TENSION COMPENSATING DEVICES Edward J. Heizer,l Mountain Lakes, and John Warwick, Livingston Township, Essex County, N. J., assignors to Specialties Development Corporation, Belleville, N. J., a corporation of New Jersey Application June 24, 1952,7Seria1No. 295,254

The present invention relates to yarn tension compensating devices, and, more particularly, to improvements for damping the movement of the yarn tension controlling means of devices such as disclosed in United States Patent No. 2,554,493,

and our respective applications for United States Letters Patent, Serial No. 135,910, filed December 3d, 1949, now Patent No. 2,629,561, and Serial No. 152,391, filed March 28, 1950, now Patent No. 2,597,044.

These devices generally comprise a pair of discs for receiving yarn therebetween to control the tension thereof, a control arm mounted for oscillation responsive to the tension in the yarn for operating means adapted to cause the discs to move apart, and a spring for resisting movement of the arm. Such an arrangement is known as, a closed mechanical system wherein forces affecting one moving part influence the other moving parts. lt is thus desirable to minimize friction in order to avoid tension variations. This makes the devicesvery sensitive but unstable when extra energy is suddenly introduced into the system.

For example, sudden introduction of energy may be caused by plucking or erratic delivery Yof. the yarn from a yarn supply package. The control arm must then move rapidly to cause positioning of the discs to compensate for such tension variables, and, Vdue to inertia effects, the arm overrides its true compensating position. A tension drop thereby results causing the force exerted by the tensioned yarn to be less than the force exerted by the spring which governs the arm. The arm then returns rapidly and again overrides itself causing a tension surge which stretches the yarn. The elastic nature of the yarn may now cause this hunting condition to continue.

We have discovered that the foregoing diiculties can be overcome by damping the' movement of the control arm to minimize the amplitude of oscillation thereof in a manner whereby the arm is readily movable by small or slowly applied forces but resists movements due to large or'suddenly applied forces. Y

Accordingly, an object of the present invention is to accomplish the Vforegoingv in an extremely simple, practical and'economical mannen 'l Another object is to vprovide damping means 3 Claims. (Cl. 242-150) and one of the elements being movable with the control arm.

Other and further objects of the invention Vwill be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

In accordance with the invention, the foregoing objects may be accomplished by applying a compound between two or more surfaces that have relative motion to each other which compound has a strong retarding action to motion by a force suddenly applied, but does not retard motion due to a slowly applied force and instead acts like a lubricant.

-We have discovered that films of silicone greases have this peculiar property. When subjected to shearing action, the iilms tend to retard relative motion between adjacent surfaces.

However, if these surfaces move slowly re1atively to each other, this retardation is barely perceptible and for all practical purposes can be considered zero. This means that the force required to slowly move the surfaces having the lm therebetween is negligible, and, therefore, does not iniluence the force applied to the control arm by the spring whereby the sensitivity of the tension compensating device is maintained but its tendency to hunt is eliminated.

While various forms of silicone greases hav ing this peculiar property when subjected to shearing may be utilized, a silicone grease has been employed successfully which is supplied by Dow Corning Corporation, Midland, Michigan, under the trade name silicone compound DC-ll. This compound is relatively heavy bodied and is somewhat tacky but has a smooth, grease-like texture. The general characteristics of this compound are as follows:

l. It does not harden at temperatures aboveY the accuracy of the tension compensating devices.

is unaffected, and it does not involve any health hazard because of its non-toxicity. Furthermore; the compound can be readily removed by means of suitable solvents to clean the bearing surfaces for a fresh application of the compound.V

Tests have indicated that an application of thev compound retains its dual functions:v of. aV lubricating and damping means for more than two years.

In the drawing, which serves to illustrate the application of the present invention by way of example in connection with the devices disclosed in the aforementioned` patents:

Fig, l is a longitudinal sectional View of a tension compensating device. such asv illustrated and described in Patent No. 2,554,43.

Fig.. 2 is a longitudinal sectional view of a tension compensating device such as illustrated and described in Patent No.. 2,629,561; and

Fig. 3. is a longitudinal sectional View of a tension compensating device such as illustrated and described in Patent No. 2,597,044.

Referring to the; drawing-'in detail and more particularly to. Fig. l thereof, there is shown a tension compensating device, which, for the purpose of understand-ing the present invention, generally comprises a pair of friction discs lll and H between which yarn is adapted tov passv to. be tensioned, a spring i2 acting on the disc, i i toV move it away from the disc i@ to diminish theV tension applied to the yarn by the discs, a cam and follower assembly le normally holding the disc H against the disc lil including a sleeve-like cage i5, a housing it on which the cage is rotatably` mounted, an arm il (partially shown) which in response to tension in the yarn is adapted to turn the cage, and a compensating spring iS inthe housing for opposing turning of the cage by the arm.

In this device, the cage and the housing constitute relatively movable elements, the end `sur-- face Qt? of the cage bears against the surface, 2i of the inner face of the housing, the arm I 'i is adapted to move the cage., and a film of silicone grease is disposed between the. surfaces and El which film acts both as a lubricating and damping meansV in the manner set forth herein.

In' Fig. 2, another type of tension compensating device is shown, which, for the purpose of understanding thc present invention, generally comprises two pairs of friction discs and 3| (of which only one pair is shown) between which yarn is adapted to pass to be tensioned,v a spring acting on the disc fili tc hold the same against the disc 3|, a housing structure 33, mechanism for moving the disc Se away from the disc 3i to diminish the tension applied to the yarn including a pin M engaging the disc 3e, a shaft 35 rotatably supported by the housing structure and an element 3S on one end of the shaft' having means @l thereon ecccntrically positioned with respectto the shaft for effecting raising and lowering of the pin, an arm 3a (partially shown)r on the element which in response to tension in the yarn is adapted to turn the shaft, a disc iii) on the other end of the shaft disposed in the housing structure, and a compensatingspring il in the housing structure and connected to the disc for opposing turning of the shaft by the arm.

In this device, the disc and the housing structure constitute relatively movable elements, the circular end surface 42 of the disc d is adjacent the surface.- 44? of the inner face of the housing, the arm is adapted to effect movement of the disc 40, and a nlm of silicone grease SG is disposed between the surfaces 42 and 44 which lm acts, as; a dampingI means and like a lubricant in the manner set forth herein.

In Fig. 3, still another type of tension compensating device. isv sho-wn, which, for the purpose of understanding thepresent invention, generally comprises; apar. of friction discs and 5l between which yarn is adapted to pass to be tensioned,I a base 52, a leaf spring 54 mounted on the base and acting on the disc 5| to hold the sanie-V against the disc 50, mechanism for moving the disc 5| away from the disc 5i) to diminish tension applied to the yarn including a member 55 on the. base having a threaded bore and a threaded. member 55 mounted in the bore. for turning movement, and provided with pin means 51 for. ,effecting raising, and lowering of the. disc 5|.,l an arm 59 (partially shown) on the member 55 which in response to tension in the yarn is adapted to turn the member 55, andA a compensating spring i connected to the member 56. for opposing turning thereof by the arm.

In this device, the member 56 carries a shallow cup 8l and the member has a hub. portion 52 facing the cup, the cup and hub portion constituting relatively movable elements. The annular end surface fili of the hub portion is adjacent the upwardly facing surface of the. cup, the, arm is adapted toY effect, turning movement of the cup with respect. to the hub portion, and a. mass of silicone grease SG is stored in the cupv between the surfaces 54 and 65 which mass acts as a damping means and like a lubricant in the manner set forth herein.

The operation of each of the tension compensating devices illustrated and described herein is similar in that the oscillating arms respond to tension in the yarn and vary the tension applied to thel yarn by the discs, and in each instance the adjacent surfaces having the silicone grease therebetween are. effective to damp relative movement of the elements formed with these surfaces when an attempt is made to. move the Surfaces rapidly with respect to each other, whereu by the, amplitude of oscillation of the arm is minimized and hunting is practically eliminated. ln this manner.. more uniform tension compensation is attainedin that the tensionY put into the yarn varies only slightly under extreme conditions from the predetermined tension to be applied to the yarn.

While the present invention has been demonstrated by examples of` applying the silicone grease between specific adjacent surfaces of' the tension compensating devices, it will be understood that other relatively' movable adjacent surn faces associated with the devices could similarly have silicone grease therebetween to accomplish the advantagesv of the present invention.

From the foregoing description, it will be seen that the present invention provides a simple and practical solutionV of a problem inherent. to. coin pensating devicesL of the precision type in particular. Hunting and extreme conditions are thus eliminated in an economical and reliable manner.

As various. changes may be made in the form,

construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense.

We claim:

l. In a yarn tension compensating device, the combination of means for receiving yarn therebetween to control the tension thereof, a pair of relatively movable elements each having a surface adjacent the other, oscillating means responsive to the tension in the yarn for moving one of said elements and controlling said first mentioned means, and silicone grease between said surfaces serving to act like a lubricant when said surfaces are moved relatively slowly with respect to each other and serving a damp relative movement of said elements when an attempt is made to move said surfaces rapidly with respect to each other, whereby to minimize the amplitude of oscillation of said oscillating means.

2. In a yarn tension compensating device, the combination of means for receiving yarn therebetween to control the tension thereof, a pair of relatively movable elements each having a surface adjacent the other, oscillating means including an arm responsive to the tension in the yarn for moving one of said elements and controlling said first mentioned means, and silicone grease between said surfaces serving to act like a lubricant when said surfaces are moved relatively slowly with respect to each other and serving to damp relative movement of said ele- 6 ments when an attempt is made to move said surfaces rapidly with respect to each other, where* by to minimize the amplitude of oscillation of said arm.

3. In a yarn tension compensating device, the combination of means for receiving yarn therebetween to control the tension thereof, a pair of relatively movable elements each having a surface adjacent the other, means responsive to the tension in the yarn including a pivotally mounted arm and a return spring for moving one of said elements and controlling said first mentioned means, and silicone grease between said surfaces serving to act like a lubricant when said surfaces are moved relatively slowly with respect to each other and serving to damp relative movement of said elements when an attempt is made to move said surfaces rapidly with respect to each other and to damp the reaction of said spring, whereby to minimize the amplitude of y oscillation of said arm and hunting of said first mentioned means.

EDWARD J. I-IEIZER. JOHN WARWICK.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date 2,507,182 Young May 9, 1950 2,554,493 Heizer May 29, 1951 2,588,914 Dunham Mar. 11, 1952 2,597,044 Warwick May 20, 1952 2,629,561 Heizer Feb. 24, 1953

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