US2716779A - Means for drafting textile fibers - Google Patents

Description

P 6, 1955 W. G. REYNOLDS 2,716,779

MEANS FOR DRAFTING TEXTILE FIBERS Filed Nov. 16, 1950 3 Sheets-Sheet l WILL/AM 6 4% W01 05,

I IN VENTOR I BY ATTORNEYS.

Sept. 6, 1955 w. G. REYNOLDS 2,715,779

MEANS FOR DRAFTING TEXTILE FIBERS Filed Nov. 16, 1950 3 Sheets-Sheet 2 Sept. 6, 1955 w. G. REYNOLDS MEANS FOR DRAFTING TEXTILE FIBERS I5 Sheets-Sheet 3 Filed Nov. 16, 1950 ATTORNEYS United States Patent MEANS FOR DRAFTING TEXTILE FIBERS William G. Reynolds, St. Petersburg, Fla. Application November 16, 1950, Serial No. 195,945

3 Claims. (Cl. 19-131) This invention relates to a means for drawing textile fibers for roving or spinning, by means of which increased control is obtained while drafting the strand to produce a more uniform and smoother product having greater tensile strength.

Prior to the present invention, many attempts have been made to gain added control over the fibers making up the strand, while the strand is being attenuated. These prior efforts have fallen into two classes: In one class, control is regained by reforming the strand in nondr'afting zones; the other has attempted to control the fibers within the drafting zone and operated upon a principle of restraining, or holding back, the moving strand. Specifically, prior devices have taken the form of pairs of aprons, between which the strand moves, the aprons being driven by the restraining or holding rolls; a single .apron, driven by one of the restraining rolls, with a small slip roll above the apron; or, fixed guides through which the strand is drawn. Small freely rotating rollers have also been employed; but, as these are operated by frictional contact with the moving strand, they also have a restraining effect upon the fibers.

All of these various forms of control were either stationary or moved slower than the strand, their effect was to double back stray fibers into the strand, thus reducing the effective fiber length and tending to disturb the parall'elizanon of the fibers making up the strand. This led to frequent disruption of'the strand. It is impossible, with these devices, to maintain control up to the point where the draft is completed, and thus control is lost at the most critical. stage of the drafting.

The present invention contemplates approximating, as closely as .possible,-the action of the human fingers in performing the operation known as stapling. In that operation, a group of fibers are grasped near their ends between the thumb and forefinger of one hand. The

thumb and forefinger of the other hand are then brought toward the opposite sides of the group of fibers and at the same time moved toward the opposite ends of the fibers. Stray ends of the fibers are thus brushed toward the end of the group of fibers; and, as the pressure between the fingers is increased, the ends of the fibers will be urged away from the holding fingers so that they will be pulled to their full length. As the pressure of the fingers is not positive, the fibers will not be pulled from between the holding fingers but will be completely smoothed and straightened. This action is repeated until the fibers are completely straightened and all be parallel throughout their lengths.

It is the object of the invention to provide a method and means for achieving this result upon a continuously moving strand in a drafting zone prior to the positive grip of the pulling force.

It is a further object of the invention to provide such a method and means wherein the strand will be progressively subjected first to a brushing in the direction of strand movement to lead stray fibers forwardly in the direction of strand travel, secondly to subject the strand ice to a gradually increasing enclosing pressure moving in the direction of strand travel to urge forward the leading ends of the fibers to extend the fibers to full length, and last to positively grip the fibers to complete the draft.

It is another object of the invention to provide such a method wherein the pressure of the holding means upon the strand is variable and applied in direct ratio to the need for the load.

The invention further contemplates the provision of mechanical means for carrying out this method of fiber control.

This application is a continuation in part of my copending application Serial Number 98,995, filed June 14, 1949, for Method and Means for Drawing Textile Fibers, now abandoned.

Other objects and advantages of the invention will become apparent from the following detailed description of the method employed, and one practical embodiment of that method, when taken in conjunction with the drawings which accompany and form a part of this specification.

In the drawings:

Figure l is a top plan view of conventional drawing rolls, one means for practicing the invention being shown in connection therewith;

Figure 2 is a longitudinal sectional view of the structure shown in Figure l, and being taken along the line 2-2 in Figure 1;

Figure 3 is a vertical section taken substantially on the line 33 of Figure 1;

Figure 4 is an isometric view of one end of the guide plate, and the means for supporting the guide plate;

Figure 5 is a schematic view of the upper left-hand portion of Figure '3, taken on an enlarged scale;

Figure 6 is a view similar to Figure 3, illustrating means for weighting the upper holding or restraining roll; and,

Figure 7 is a view similar to Figure 4, showing a modified form of cradle for supporting the guides.

Referring to the drawings in detail which show a draft section of a spinning machine, or other device for the attenuation of textile fibers, a plurality of roll stands 1 is shown in which are mounted three lower drawing rolls 2, 3, and 4. There are also upper drawing rolls 2', 3, and 4 rotatably mounted at their ends in cap plates 15 pivoted at 16 in a conventional manner. The roll pairs are mounted in the usual manner, with the upper or pressure rolls slightly offset with respect to the lower driven rolls. Rolls 4 and 4", which initially receive the strand, rotate slightly slower than do rolls 3 and 3', but no appreciable drawing is done between these pairs of rolls. Rolls 2 and 2', however, rotate at a greatly increased rate over rolls 3 and 3 and do the actual drafting. The rolls 2 and 2 will be referred to herein as the terminal rolls, and rolls 3 and 3 as the restraining rolls.

It will be noted that the upper roller 3' is comparatively small in diameter and light in weight to permit some slippage between the rolls 3 and 3, as is well known in the art. It has been found that when making high-er drafts, such as from 36 to 70, for example, it is necessary to add a little weight to the top restraining roll 3'. A one pound weight upon the roll has been found satifsactory with an average 50 draft. It will be understood that rolls 3 and 3 exercise a restraining force upon the strand and rolls 2 and 2' a pulling force. Thus, the contacts of the rolls 2 and 2' and 3 and 3 with the strand, establish the points between which control of the drawing is effected. The bottom rolls 2, 3 and 4 are of metal, and may have their bosses finished either by fluting or knurling. The top rolls 2' and '3' may be metal or composition, and also may be fluted or knurled. This much of the apparatus is conventional.

With this in mind, the present invention contemplates a method of drawing a fiber strand S, by which the strand and the fibers which make up the strand are successively subjected to three distinct operations: First, to bring stray fibers back to the strand, next to straighten the fibers to extend them to their full lengths and at the same time lead the forward ends toward the nip so that the actual draft is begun, and then while holding the fibers straight complete the draft. This is accomplished by first brushing the strand lightly in the direction of strand travel to lead the stray fibers forward and toward the strand. The strand is then enclosed, the enclosing pressure being gradually applied so that the leading ends of the fibers are gently pulled forward while the rear ends of the fibers are restrained, so that they will be completely straightened. As the enclosing pressure is increased, its action on the fibers will be increased so that the fibers will begin to move forward. This will continue until the leading ends of the fibers are gripped by the drawing force and the draft will be completed. Thus, the fibers will be extended to full length before the actual draft, and the fibers will be in movement before they are positively gripped by the drawing force. This will result in a more uniform feeding of short and longer fibers giving a more uniform distribution of the fibers in the finished product. It will result in a stronger product because of this more even distribution and because all of the fibers are extended to their full lengths.

To carry out this method, certain mechanism is employed. It was previously mentioned that the upper terminal, or drawing, roll 2' is offset with respect to the lower roll. This roll 2' is positioned forwardly (in the direction of strand travel) of a plane normal to the path of the strand, and passing through the axis of the lower roll. A guide bar is mounted, in a manner to be described, between the roll pairs 2, 2', 3 and 3, and an endless belt is put around the upper roll 2' and the guide bar, with its lower flight adapted to contact the strand. The guide bar 5 is provided with a rail 7 which is positioned transversely of the path of the strand. The rail has its back top and bottom edges rounded to form a smooth surface about which the belt may turn with little friction; and the belt, in running around the bar, exerts a pulling force upon the bar which serves to pull the bar down into operative position. The rearward inclination of the guide aids in achieving this result. The guide bar 5 is so positioned that its rail 7 will hold the belt, as it begins its bottom flight, slightly above the strand. The angle of the bottom flight of the belt, with respect to the strand and the bottom roll 2, is such that the belt makes actual contact with the body of the strand as the strand lands upon the periphery of the lower roll 2. Due to the fact that the upper roll 2 is ofiset forwardly, this initial actual contact of the belt with the strand is behind the nip between the rolls 2 and 2'. In oher words, the strand lands upon the periphery of the lower roll and is therefore backed by the roll, as the belt contacts the strand. Thus, the strand is brought between two surfaces, the surface of the lower roll and the bottom of the belt, which surfaces are moving faster than the body of the strand but at equal speed to one another. The lower roll and belt enclose the strand between them with a gradually increasing pressure as the nip of the rolls is approached. The flexibility of the belt permits some yielding of the belt so that the grip upon the leading ends of the fibers in the strand is not a positive one, and not sufficient to draw the trailing ends of the fibers from between the iii] (iii

restraining rolls, but it is sufficient to exert a pull upon the r leading ends of fibers not yet engaged by the nip of the rolls to pull these fibers to their full lengths. In other words, the pull will extend the individual fibers until they are absolutely straight. As the nip of the rolls is appreached, the pressure exerted upon the strand between v;

the belt and lower roll will increase to the point that some actual bodily movement of these fibers will take place to the end that these fibers will be in motion relative to the other fibers of the strand when they enter the nip of the rolls. Of course, when the leading ends of the fibrs enter the nip of the drawing rolls, these fibers then move at the speed of the drawing rolls, so that fibers, rolls, and belt are moving at the same speed. Thus, it will be seen that the belt will first brush the stray fibers forwardly toward the body of the strand from the point where the belt turns about the guide rail until the strand lands upon the lower roll, whereupon the belt actually contacts the body of the strand and the strand is subjected to a gradually increasing pressure to straighten the fibers, and then the fibers enter the nip of the drawing rolls and the drawing is completed.

A conventional section of rolls is shown in Figures 1, 3 and 6 to accommodate but two strands S, but it will be understood that there will be a belt 6 and its component guide bar for each spindle of the complete machine. For simplicity of construction the guide bar is made to accommodate two belts so that each bar may fit between a pair of cap plates. The guide bar is provided with a pair of fingers 8 and 8 of any suitable form to lightly contact the inner edges of the respective belts to prevent the belts from sliding laterally. The fingers 8 and 8' are shown spaced to permit the usual saddle stirrup to pass between them. The saddle bears upon the upper rolls 2' and 4 as shown in Figure 6 and is connected to a weight lever by means of the stirrup. The guide bar 7 is also provided at its ends with uprising guiding portions 9 and 9' which serve the same function insofar as the outer edges of the belts are concerned, but these guiding portions 9 and 9 are made somewhat wider than the guide bar fingers 8 and 8' so that they may also serve to fit in supports mounted on the cap plates which support the upper rolls 2 and 3, to maintain the guide bar in proper alignment, said supports to be presently described.

Although it has been found that the guide bar will work quite well while simply floating, it may be desirable to provide means for vertical adjustment to prevent it from moving downward beyond a predetermined level. To this end, two forms of cradle have been shown. In Figures 1, 2, 3 and 4, there is illustrated an adjustable cradle 17 of any suitable resilient material having a notch 18 therein to coincide with the conventional notch 19 in the cap plate through which the top rolls 3 are passed for installation and removal. The adjustable cradle 17 has a slot 20 therein loosely penetrated by a screw 21 which is threaded in the cap plate. The cradle 17 also has a set screw 22 threadably mounted therein which engages the top of the cap plate and whereby the free end of the adjustable cradle 17 may be adjusted vertically. The adjustable cradle 17 has a downwardly depending hook portion 23 into which the guiding portion 9 on the end of the guide bar 7 loosely fits. The adjustable cradle 1'. and associated parts are identical to adjustable cradle 17 and associated parts, except the adjustable cradle 17' is opposite hand, and like reference characters with the prime notation will apply.

A modified form of cradle is shown in Figure 7 and indicated as 24. This cradle has some advantages over that previously described, as it lies wholly above the space in which the rolls operate and is adapted to support the adjacent ends of a pair of guide brackets. The cradle is formed from a single sheet of spring material and is cut so as to form a head portion 25 and a pair of legs 26 extending from the head portion. The material which is cut away in forming the head and reduced width legs is turned upwardly to form a pair of seats 27 to receive the ends of the guide. The head of the plates is provided with a slot 28 and the plate is clamped to the frame of the machine by means of the screw 29 which passes through the slot 28. The plate can be moved backward or forward as desired and held in positions of adjustment by tightening the screw 29. Each of the legs has at its forward end a set screw 30 which is threaded through 5 the material of the leg. By adjustment of these screws which pass through the legs and rest upon the-frame, the spring material of the leg may be flexed to raise or lower the seat 27 which is carried by that le Lock nuts 31 are provided for each of the screws 30 to hold them in positions of adjustment.

The provision of the belt, asdescribed, changes the shape of the throat leading to the nip of the terminal rolls. Instead of the relatively wide angle formed by the converging arcs of the peripheries of the rolls making up the pair, the throat is now formed by the arc of the lower roller and the relatively fiat surface of the bottom flight of the belt. This narrows the angle of the throat by substantially half, and thus provides for a more gradual gripping of the strand over a greater are of the lower roll. The position of the guide bar will depend upon the length of fiber in the strand, and it is positioned farther from the terminal rolls as the fiber is proportionately longer, so that initial contact with the strand may be made at proportionately increasing distances from the terminal rolls as the fiber length increases.

The results obtained through the practice of the present invention are due to a number of factors. In the first place, the strand is initially acted upon well back of the terminal rolls while the strand is still consolidated, and consolidation is maintained by continuous contact up to and through the nip of the terminal rolls. By employing the belt, and reducing the angle of the throat, there is no sudden gripping of the fibers by the terminal rolls but the hold upon the fibers is progressively gained by the walls of the throat which are moving in the direction of travel of the strand, thereby resulting in a straightening of the fibers and more uniform feed of short and long fibers to the terminal rolls.

The resulting product, having straight fibers and a more uniform distribution of short and long fibers, has considerable more tensile strength than the product made by ordinary methods. Tests have shown it to be smoother, and to have a breaking point far in excess of that made by other methods.

It might be stated that the guide bar 5 with its rail 7 is shown in the drawings in an exaggerated position somewhat higher than it would occupy in actual practice. It would be so positioned that the rear end of the lower flight of the belt would engage the strand very lightly to exert a slight brushing effect on the strand, which contact would increase gradually until contact is made with the lower terminal roll. Although the belts and associated apparatus are shown above the strand, it is to be understood that it could be located on the lower side of the strand instead, in which event, the upper drawing roll 2 would have to be positioned to the rear of a plane passing through the axis of the lower roll and normal to the path of the strand.

As previously mentioned, it may be desirable at times to provide extra Weight upon the restraining roll, so as to give more complete control over the strand at this point. This is particularly desirable when making high drafts. It has been found that a dead weight upon the upper slip roll will not give the desired result. Often in the spinning of yarn a pair of rovings will be fed simultaneously through the drawing frame; and, from this pair of rovings, a single yarn will be spun. Although all roving is round in cross-section when it is made, the winding of the roving upon the bobbin will cause it to flatten slightly and when it is unwound and fed to the spinning machine it passes through the drawing rolls in this flattened condition. It is impossible to feed these rovings to the drafting rolls without the yarn rotating to some extent and there are times when one of these flattened rovings will be passing between the restraining rolls presenting its thinner dimension to the pressure of the rolls while the other roving may be presenting its thicker dimension to the pressure of the rolls. It is absolutely essential that the pressure on the two he uni- 6. form, and yet the upper restraining roll must becap'able'oi yielding to this thicker dimension as it is 'first presented to the roll. By providing a resilient weighting, any en largement of the strand will cause the upper restraining roll to lift and in so doing will increase the weighting of the roll. This additional weighting will tend to draw the roll back to its original positionand reduce the enlargement to the normal size .of the strand. In other words, the roll may yield to irregularities of t e strand, and its weighting will be variable so that where there are few fibers in the strand the weighting will be light and as the number of fibers in the strand increases the weight will be increased to maintain the uniform control over all of the fibers. One means for accomplishing this result has been shown in Figure 6, wherein a hook-like link 32 is hooked over the reduced center portion of the upper restraining roller 3 and an elastic band 33 is connected to the lower end of the link and passes around the usual Weight lever 34. A number of holes 35 may be drilled in the Weight lever and a pin 36 provided, so that the elastic band may be moved various distances from the fulcrum of the lever to increase its pull upon the restraining roll and maintained in this'position by slipping the pin 36 through the desired opening 35. It will, of course, be evident that a light spring could be substituted for the elastic band.

While in the above, the methodof the present invention and one practical embodiment of the method have been disclosed, it will be understood that changes may be made from the precise structure shown without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. Means for drafting a fiber strand comprising, pairs of rolls spaced apart, one pair being restraining rolls and the other terminal drafting rolls adapted to elongate a strand passing between the roll pairs, a guide bar positioned between the roll pairs having a rail lying substantially in a plane parallel to the tops of the bottom rolls of the roll pairs and having upwardly extending spaced guide fingers, and a belt surrounding and driven by one of said terminal rolls and passing around the rail and between the guide fingers of said guide bar, the lower flight of the belt having its end disposed around the rail at a slightly higher elevation with respect to the strand than the end of the flight contacting the terminal rolls whereby light initial contact is made with the strand and maintained with the strand at gradually increasing pressure at the speed of the terminal rolls over an appreciable distance within the drafting zone up to and including the nip between the terminal rolls.

2. In drafting means as claimed in claim 1, said roll pairs being mounted in a frame, adjustable cradles each provided with a hook to form a seat for the guide bar and mounted in said frame between said roll mountings, said guide bar having side fingers to fit in said hooks, and means carried by said adjustable cradles to adjust the position of said guide bar relative to said rolls.

3. Means for drafting a fiber strand comprising, spaced pairs of rolls, one pair being restraining rolls and the other terminal drafting rolls adapted to elongate a strand passing between them, the axis of rotation of the top terminal roll being disposed forwardly of a plane which includes the axis of the lower terminal roll and is normal to the path of the strand, a guide bar positioned between the roll pairs having a rail, a belt passing around one of said terminal rolls and the rail of said guide, said guide bar being so positioned that the bottom flight of said belt when it passes around the rail will be slightly removed from the body of said strand but said belt will contact the body of said strand substantially at the point that said strand contacts the other of said drafting rolls, whereby said belt will first brush stray fibers forwardly and toward the body of the strand and then the belt with said other drafting roll will exert a gradually increasing enclosing References Cited in the file of this patent UNITED STATES PATENTS Thompson Oct. 27, 1891 Calvert Feb. 16, 1937 10 Reynolds Apr. 15, 1941 8 Jones et al. Apr. 22, 1941 Cobb Dec. 15, 1942 Piron Jan. 27, 1948 Klein June 16, 1953 FOREIGN PATENTS Great Britain Nov. 22, 1917 France Dec. 2, 1920 France Nov. 15, 1946

Claims (1)

1. MEANS FOR DRAFTING A FIBER STRAND COMPRISING, PAIRS OF ROLLS SPACED APART, ONE PAIR BEING RESTRAINING ROLLS AND THE OTHER TERMINAL DRAFTING ROLLS ADAPTED TO ELONGATE A STRAND PASSING BETWEEN THE ROLL PAIRS, A GUIDE BAR POSITIONED BETWEEN THE ROLL PAIRS HAVING A RAIL LYING SUBSTANTIALLY IN A PLANE PARALLEL TO THE TOPS OF THE BOTTOM ROLLS OF THE ROLL PAIRS AND HAVING UPWARDLY EXTENDING SPACED GUIDE FINGERS, AND A BELT SURROUNDING AND DRIVEN BY ONE OF SAID TERMINAL ROLLS AND PASSING AROUND THE RAIL AND BETWEEN THE GUIDE FINGERS OF SAID GUIDE BAR, THE LOWER FLIGHT OF THE BELT HAVING ITS END DISPOSED AROUND THE RAIL AT A SLIGHTLY HIGHER ELEVATION WITH RESPECT TO THE STRAND THAN THE END OF THE FLIGHT CONTACTING THE TERMINAL ROLLS WHEREBY LIGHT INITIAL CONTACT IS MAKE WITH THE STRAND AND MAINTAINED WITH THE STRAND AT GRADUALLY INCREASING PRESSURE AT THE SPEED OF THE TERMINAL ROLLS OVER AN APPRECIABLE DISTANCE WITHIN THE DRAFTING ZONE UP TO AND INCLUDING THE NIP BETWEEN THE TERMINAL ROLLS.

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