US3005340A - Fiber drafting analyzer - Google Patents

Description

Oct. 24, 1961 R. A. SMITH FIBER DRAFTING ANALYZER Filed Oct. 11, 1957 United States Patent 3,005,340 FIBER DRAFTING ANALYZER Robert A. Smith, Drexel Hill, Pa., assign-or to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware Filed Oct. 11, 1957, Ser. No. 689,588 2 Claims. (Cl. 73-159) This invention relates to a testing device for measuring the force required to draft a sliver, roving or like bundle of fibers to facilitate the study of the frictional resistance to slippage of staple fibers past one another in the direction of their longitudinal axes during the attenuation of the sliver into roving and the subsequent attenuation of the roving.

In the production of yarn from staple fibers, whether natural or man-made, the randomly arranged, relatively short fibers are first subjected to a process known as carding in order to arrange the fibers in generally parallel relationship. The carding process results in what is known as a sliver which is an elongated rope-like structure in untwisted form whereinthe fibers are rather loosely held together. The sliver is then drafted or attenuated so that the fibers are slipped endwise past one another to greatly increase the length of the structure and consequently decrease the cross-sectional area. As the cross-section is decreased the bundle of filaments is twisted very slightly in order to hold the fibers together. After a considerable amount of attenuation the strand reaches a stage known as roving wherein the fibers are still arranged in generally parallel relation and the tensilestrength is still very low because there is only a slight amount of twist. The roving is then spun into a yarn strand. 7

The force required for drafting sliver and roving of different materials varies consider-ably, as does the total amount of attenuation which it is possible to obtain while still producing a yarn of substantial strength. In the operation of a textile mill it is highly important to know the frictional forces involved in slipping the fibers of the sliver or roving past one another. Among the factors affecting these forces is the finish applied to the fibers. As is generally known, various finishes are applied to staple fibers, the particular finish depending in large degree upon the physical characteristics of the fiber itself. One desirable attribute of a finished fiber is that its frictional characteristics should not change with age or with variations in atmospheric conditions It is a matter of common knowledge that a finish which is entirely satisfactory when first applied, after aging or under different humidity conditions may develop a tendency to changeits coeihcient of friction sufliciently to cause adhesion of the fibers to one another, thus preventing the roving from drafting when subjected to normal drafting force.

While it is obvious that a knowledge of the frictional forces involved in drafting would enable better finishes to be developed and would be of value to the mill operator in setting his machinery for the ideal twist for the particular material that was being operated upon, heretofore it has not been possible to accurately evaluate the frictional resistance of the fibers to slip past one another under practical drafting conditions.

It is the primary object of the present invention to provide a device wherein the actual drafting conditions encountered in a mill may be simulated and by means of which device the frictional forces involved during drafting may be accurately measured.

It is a more general object of this invention to provide a research tool which will facilitate the study of the 3,005,340 Patented Oct. 24, 1961 2 frictional forces involved in drafting sliver, roving or like bundles of fibers.

Other and more particular objects, features, and advantages of the invention will become apparent as the description of a preferred embodiment thereof proceeds.

Referring now to the drawing;

The figure is a diagrammatic view partially in side elevation of a device constructed in accordance with this invention.

- The device generally comprises a pair of input feed rolls 10 and 11 and a pair of output rolls 12 and 13. The lower input feed roll 11 is secured to a shaft 14 mounted in stationary bearings while the upper input feed roll 10 is secured to a shaft '15 mounted in a bearing block 16 slidably mounted upon a pair of guide pins 17 and 18 fixed in the main framework generally indicated at 19. A plunger 20 is secured to the bearing block 16 and a spring 21 extends between the upper -end of said plunger and the framework 19 to urge the upper feed roll 10 into engagement with the lower feed roll 11. The plunger 20 is provided with a cutout portion 22 extending into which is a flattened shaft 23 rotatably mounted in the framework 19 and provided with an operating handle 24. By moving the handle 24 downwardly from the position shown in the drawing, the flattened portion of the shaft 23 is brought into engagement with the cutout portion 22 to thereby raise the plunger 20 against the action of the spring 21 and release the feed roll 10 from engagement with the feed roll 11.

The output roll .12 is secured to a shaft 25 rotatable in stationary bearings and the output roll '13 is secured to a shaft 26 mounted in a manner identical to that of the shaft 15 of the input feed roll 10.

The input feed rolls 10' and 11 are drivingly connected to the output rolls 12 and 13 by means of a gear 27 fixed to the shaft 14 and a gear 28 secured to the shaft 25, said gears being interconnected througha pinion 29. The gearing arrangement is such that the output rolls are driven at a speed slightly in excess of the speed of the input feed rolls and by changing the various gears the ratio of the speed of the output rolls to that of the input feed rolls may be varied as desired.

Splined tothe shaft 14 at the end opposite the gear 27 is a gear 30 with which is meshed a drive gear 31 splined on ashaft 32 to which is secured a sprocket 33 driven by a sprocket chain 34 which in turn is driven from a suitable motor, not shown.

The sliver, rovingor like bundle of fibers 35 whose frictional resistance to drafting it is desired to test is fed between the input feed rolls 10 and 11 and thence upwardly over a sensing roller36 freely rotatable upon a shaft 37 extending between the arms of a yoke 38 provided on the lower end of a plunger 39 of an electronic strain gauge, the purpose of which will presently be described. From the roller 36 the sliver or the like is extended downwardly and between the output rolls 12 and 13. In the textile art the point of engagement between rolls is referred to as the nip of the rolls, since it is at this point that the material passing between the rolls is squeezed or nipped. From the drawing it will be observed that the two sets of rolls are mounted on parallel axes and that planes tangential to the nips of the two sets of rolls intersect at a right angle and it will also be observed that the sensing roller 36 is tangent to the nip of the output rolls 12 and 13.

Since the roller 36 is freely rotatable, the drafting of the sliver or roving caused by the differences in speed between the output rolls and the input feed rolls will take place between the nip of the output rolls and the point where the sliver or roving leaves the roller 36 and the frictional resistance offered by the slippage of the fibers past one another during this drafting or attenuation of the strand will produce a downward pull on the roller 36 and the plunger 39. The plunger 39 is mounted within a sleeve 40 secured in an arm 41 adjustably mounted upon a post 42 forming a part of the framework of the device and said plunger is operatively connected through a. transducer 43 to a suitable recording device 44. The particular transducer and recording device employed are not of the essence of this invention but preferably the recording device is of a type which indicates on a graph the variations in vertical movement of the roller 36 as converted into electrical energy by the transducer 43.

A pointer 45 is carried by the arm 41 and by adjusting the height of said arm in accordance with the indications of said pointer in cooperation with a scale 46 provided upon the post 42, the height of the sensing roller 36 may be adjusted so that a distance between the nip of the output rolls '12 and 13 and the point where the sliver or roving leaves the sensing roller is only slightly in excess of the length of the staple fibers making up the strand. If conditions similar to those encountered in a mill are to be simulated, it is essential that the distance between the sensing roller 36 and the output rolls be adjustable since the sensing roll 36 of the present device in effect takes the place of the back feed rolls of standard textile machines and if this distance is substantially greater than the fiber length, almost no force will be required to completely separate the fibers and break the strand, and if this distance is too short there will be a tendency to elongate or break the individual fibers rather than to slip the fibers past one another.

Since the sensing roller 36 is an idler roller, even though it effectively serves as a drafting point, it is capable of accurately measuring the frictional forces involved in drafting the sliver, unaffected by other factors which are present when an attempt is made to take readings from the drafting rolls themselves.

Since, as previously mentioned, the present device is primarily a research tool, it is desirable that the electronic strain gauge comprising the sensing roller 36 and recorder 44 be of the type wherein the speed of the chart of the recorder may be varied or regulated. There are a number of such gauges on the market and one which has been found to be satisfactory is manufactured by the Brush Electronics Company of Cleveland, Ohio. The Brush gauge comprises a transducer, amplifier, direct writing oscillograph and a sensing element herein shown as the roller 36 and is equipped with a three-speed transmission whereby chart speeds of 1, and 25 units per given length of time may be obtained. By changing the ratio of the drive gears 30 and 31 the sliver or roving may be made to advance through the feed rolls and 11 at the same speed as the chart movement or at a known fraction or multiple thereof.

Having thus described a preferred embodiment of the invention, what is claimed is:

A device for measuring the force required to draft a sliver, roving or like bundle of fibers, comprising a first set of drafting rolls, means for driving said drafting rolls at a preselected speed, a second set of drafting rolls having axes parallel to the axes'of said first set, means for driving said second set from said first set at a greater rate of speed than said first set, said sets of drafting rolls being so positioned that planes tangential to the nips of the two sets of rolls intersect at an angle, a nicely rotatable force sensing roller located intermediate the two sets of drafting rolls, said sensing roller being tangent to the plane of the nip of said second set of drafting rolls whereby the sliver or the like running between the two sets of drafting rolls and around said sensing roller will be attenuated between said force sensing roller and said second set of drafting rolls, means operatively connected to said sensing roller for recording the tension on the sliver or the like during its attenuation, means for fixedly adjusting the position of said sensing roller so that the distance between the point where the sliver or the like leaves said sensing roller and enters the nip of said second set of drafting rolls is slightly greater than the length of the fibers making up said sliver or the like, and scale means indicating the adjusted position of said sensing roller.

2. A device for measuring the force required to draft a sliver, roving or like bundle of fibers, comprising a first set of drafting rolls, a second set of drafting rolls, means for driving said sets of rolls at preselected rates of speed with the second set being driven at a greater speed than the first set, said sets of drafting rolls being so positioned that planes tangential to the nips of the two sets of rolls intersect at a right angle, a freely rotatable force sensing roller located intermediate the two sets of drafting rolls, said sensing roller being tangent to the plane of the nip of said second set of drafting rolls whereby the sliver or the like running between the two sets of drafting rolls and over said sensing roller will be attenuated between said force sensing roller and said second set of drafting rolls, means operatively connected to said sensing roller for recording the tension on the sliver or the like during its attenuation, means fixedly adjusting the position of said sensing roller so that the distance between the point where the sliver or the like leaves said sensing roller and enters the nip of said second set of drafting rolls is slightly greater than the length of the fibers making up said sliver or the like, and scale means indicating the adjusted position of said sensing roller.

References Cited in the file of this patent UNITED STATES PATENTS

Images