US2840860A - Drafting slivers of fibrous materials - Google Patents

Description

y 1958 G. F. RAPER DRAFTING SLIVERS OF FIBROUS MATERIALS Y Filed March 20, 1953 3 Sheets-Sheet 1 FIG.1

iN VENTOR 2a T I r ql I ATTORNEYS July 1, 1958 s. F. RAPER 2,840,860

DRAF TING SLIVERS 0F FIBRQUS MATERIALS Filed March 20, 1953 3 Sheets-Sheet 2 FIG. 5

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ATTORNEYS July 1, 1958 G. F. RAPER DRAFTING SLIVERS OF FIBROUS MATERIALS 3 Sheets-Sheet 3 Filed March 20, 1953 FIG ll FIG. l3

FIGJZ FIG l5 (M-L. Em

ATTORNEYS DRAFTHNG SLIVERS F FERDUS MATERIALS George F. Raper, Masham, near Ripon, England Application March 20, 1953, Serial No. 343,549

Claims. (Cl. 19a-13ll) The invention relates to the drafting or drawing of slivers of fibrous materials by apparatus commonly re ferred to as roller drafting apparatus comprising retaining rollers, followed by drawing rollers revolving with a higher surface speed than the retaining rollers In many such arrangements, mechanisms have been employed or proposed between retaining and drawing rollers to control in a determined way, the forward movement of the fibres in the sliver undergoing draft, such mechanisms taking the form of additional rollers, or fallers or push bars or porcupines or aprons and so forth whose function is either partially to grip the fibres, or to retain twist in a twisted sliver with the same object. In general, such rotating or travelling means are open torthe objections that they are expensive to construct and maintain, that they limit the amount of draft which can be applied and that they lap or pick up fibres and need periodical cleaning.

To overcome these objections and to adhieve simplicity, l dispense with all such means between retaining and drawing rollers and substitute instead thereof a device which is by itself the only piece of apparatus situated between the retaining and drawing rollers. My device is stationary, except for the usual slow lateral traverse imparted to it, along with the sliver, across the face of the rollers for the purpose of distributing wear. The device does not rotate to twist the sliver, nor does it reciprocate to feed the sliver, and it employs no rotating or travelling members such as rollers or aprons. By its unique action on the sliver, to be described later, it obviates the need for such rollers or aprons, hitherto required to feed the sliver forward to the drawing rollers.

The invention is based on the fact that the fibres held by the drawing rollers (and known as the fast fibres) can be made to pull forward the fibres held by, or under the influence of, the retaining rollers (and known as slow fibres) by generating sufiicient inter-fibre frictional forces between them. These forces are a product of the interfibre coefficient of friction and the normal forces, i. e. forces perpendicular to the fibre axes, at any point, I therefore generate the drag between the fast and the slow fibres by applying pressure to the sliver by means of smooth stationary surfaces in the region where the fast fibres and the slow fibres have their maximum interaction, which region is in fact an area near the drawing rollers and defined precisely by the fibre-length distribution of the material.

Since, however, a large proportion of the slow fibres consists of floating fibres or fibres not actually gripped by the retaining rollers, there is a danger that the. drag generated as above described may cause these floating fibres to change prematurely from slow to fast speed and cause thereby thickness variations in the outgoing sliver. I prevent this by applying pressure in a second region, namely, that in which the interaction between these slow floating fibres actually gripped by the retaining rollers is at a maximum, this region being again. found, by calculation base on the fibre-length distribution of the material.

2,840,8fid Patented July 1,, 1958 There is a further danger that this second application of pressure by stationary surfaces might retard the slow fibres and cause rupture of the sliver due to the frictional force between the sliver and the pressure-applying surfaces. I guard against this danger by applying still fur ther pressure in the region near the drawing rollers to generate a sufficiently high total drafting force to overcome the retarding frictional forces of the pressurenpplying surfaces. A further advantage of the facility for thus regulating the total drafting force is that there is an optimum total drafting force for any sliver, to keep thickness variations to a minimum, and the method 1 cmploy for regulating this force is described below.

In practice, the two pressure zones or regions referred to above, merge, and the required result is obtainable by a certain distribution of pressure on the sliver from the retaining rollers to the drawing rollers. This dis tribution can be found by calculation from the ascertained fibre-length distribution of the material, and the ratio of the ingoing and outgoing sliver thickness. The normal forces in a sliver at any point are proportional to sliver thickness at that point divided by the cross-sectional area to which the sliver is constricted at that point. Sliver thickness at any point is ascertained by calculation from the fibre-length distribution of the material, and the ratio of the ingoing and outgoing sliver thicllnesses. Hence I arrive at the required change of crosssectional area to which the sliver must be const icted at all points between the retaining and the drawing rollers.

My invention consists therefore essentially in proiding a passageway for the sliver extending from retaining to drawing rollers, which passageway has a determined cross-sectional area from point to point calculated as above described. To achieve this I employ either separately or in combination two methods:

(1) A passageway for the sliver having internal surfaces which are fixed, whilst drafting is taking place, in such a position that the sliver is compressed to less than its natural or free cross-sectional area at any or all points.

(2) A passageway for the sliver having internal surfaces which are expanded or contracted by the thickness variations in the sliver.

In the first method, the passageway may be of preformed construction having suitably curved or sloping internal surfaces, different passageways being used for different sliver thicknesses, or it may have adjustable internal surfaces which can be pro-set for distance from, and angle of inclination to, the sliver centre-line, such surfaces being curved, if necessary, in addition to being made adjustable to secure to the required change in cross-sectional area of the passageway.

In the second method of obtaining correct pressure distribution, I cause one or more of the internal surfaces to be free to move in a direction perpendicular to the sliver axis and urged by suitable yielding means toward the sliver centre-line so that variations in sliver thickness alter the cross-sectional area of the passageway. In this arrangement the movable surface or surfaces may pivot about some point which is fixed though adjust ole, or which itself may be yielding. The pivot may be positioned in such a way that, for example, a thick place in the entering sliver expands the surfaces on entry and by contracting the exit surfaces applies more pressure on the fast fibres hence momentarily increasing the drag. The load on the yielding surfaces may be constant as for instance by weight and lever, so that the pressure on the sliver is independent of sliver thickness; or it may be produced by negatively-acting weights, springs and levers which decrease the pressure on the sliver as thickness increases and vice versa.

It will be appreciated that the particular method of pressure application used, ranging from the simplest preformed passageway to the most complicated arrangement of movable surfaces and loading, will probably be decided by the permissible cost and the degree of control of thickness variation required.

I have found in all cases that thickness variations in the sliver are produced if the sliver centre-line is out of alignment with the line joining the nip-points of the retaining and drawing rollers, that is to say the shortest path between these points. I therefore position the passageway so that the sliver is not forced out of the line it would assume if drawn merely between retaining and drawing rollers; and although the internal surface or surfaces of the passageway may be curved as above described to obtain change of cross-sectional area, the sliver centre-line remains on the shortest path between the roller nip-points.

it will be apparent from the foregoing that the invention is characterised by the provision of a method of drafting a fibrous sliver or slivers without the use of rotating or travelling means between retaining and drawing rollers according to which there is employed, in combination with retaining and drawing rollers, a passageway which extends as nearly as practicable from the one to the other, and which is formed by adjustable or movable surfaces which constrict the sliver to less than its normal cross-sectional area at any or all points, said passageway being so positioned that the sliver-centre line is aligned with a straight line between the nip-points of the retaining and drawing rollers.

In one embodiment of the invention I form a pre-set adjustable passageway by two sideplates which extend as nearly as is practicable from the retaining to the drawing rollers. Top and bottom members fit closely inside these plates and the distance from, and angle of inclination to, the sliver centre-line of either or both of the top and bottom members can be adjusted by screws, cams or the like. Alternatively, for convenience, one side and the bottom member may be integral and movable as one member, whilst the top member is held to the other side member and both are adjustable as one side member. In this case, the top member, though rigidly held to a side member in action, can be freed and slid up an elongation of the side member to open the passageway to facilitate threading of the sliver.

in another embodiment of the invention I may form a passageway which is expansible or contractible in a direction perpendicular to the sliver line by thickness-variations, by means of two sideplates which extend as nearly as is practicable from the retaining to the drawing rollers, and between which top and bottom members are closely but slidably mounted. One or both of the top and bottom members may be loaded at each end. Alternatively, either or each may be held in a fixed but adjustable pivot at one end or at some position intermediate its ends, and be loaded at some other point. Loading may be effected by weights, springs or levers or by a combination of such means. To secure a similar yielding effect, the slivercontacting surfaces of the passage-way may be formed of flexible material such as, for example, strips of phosphor bronze or other metal or material which will yield to thickness-variations in the sliver.

In some cases it may not be desirable to form the top or bottom members in one continuous piece, but to make them in two or more sections capable of independent presetting or of an independent yielding movement.

A further refinement may deal with thickness variations across the width of the sliver as for example a sliver which is naturally thicker down the centre-line than at its outer edges. This may be compensated for either by forming a slight curve on the sliver-contacting surfaces of the top and bottom members or by splitting these members lengthwise into two or more sections free to ride independently on transverse thickness-variations in the sliver.

With a view to controlling further the drafting action exerted on the fibres the front or drawing rollers may be in the form of what may be termed intersecting rollers, rollers, that is to say, one or more of such rollers, usually the bottom roller or rollers may be formed with a relatively narrow, peripheral, parallel-sided or substantially parallel-sided annular groove of suitable depth and the co-operating top roller or rollers be arranged to fit closely into this groove.

The width of this groove is made suitably less than the natural width of the entering sliver, that is to say, the natural width the sliver would assume if the drafting rollers were, as usual, plain-surfaced. The sliver being drafted is led into the nip thus formed between cooperating upper and lower rollers and is compressed thereby by four accurate surfaces, the sides of the groove confining the sliver laterally so that its ratio of thickness to width is considerably greater than is possible with plainsurfaced rollers. The result of thus confining the material into a relatively narrow, thick ribbon is that its thickness varies little across its width and in most cases the necessity for the provision of compressible covers or aprons is avoided. Advantages afforded by the proposed front or drawing roller construction are firstly, that a steady nip position is ensured with consequent less irregularity in the thickness of the outgoing sliver; secondly, the need is avoided for providing any sliver traversing means between the retaining rollers and the drawing rollers; and thirdly, that there are no straying fibres at the edges of the sliver to lap on to the rollers. Moreover, the confinement of the material so that the fibres have much more contact with each other and with the quadrilateral surrounding surface, accelerates the dispersal of static electricity, with the consequence that the drafting can be performed at much higher speeds than before without the necessity for employing anti-static precautions.

Still further, it is known that top and bottom drafting rollers have been inter-connected by gears to drive one from the other but difiiculty has been experienced, when using compressible roller coverings or endless aprons or leathers, in meshing the gears correctly. My proposed front roller construction overcomes this difficulty.

In the accompanying more or less diagrammatic drawings:

Figs. 1 and 2 are, respectively, a side and sectional elevation of one arrangement in which fixed side plates and movable top and bottom plates are employed, with means for pre-setting the top and bottom plates for distance from, and angle of inclination to, the longitudinal centre-line of the sliver;

Figs. 3 and 4 are similar views of one arrangement in which fixed side plates are employed in conjunction with a fixed but removable top plate and a bottom plate which is yieldingly urged, under pressure which may be adjustable, towards the top plate; and

Figs. 5 to 9 illustrate permissible alterations in detail which may be employed and which are hereinafter described.

Fig. 10 is a front view, and Fig. 11, a sectional end view on the line 11-11 in Fig. 10, of one front roller arrangement which may be employed; and Figs. 12 to 16 illustrate details hereinafter referred to:

Referring firstly to Figs. 1 and 2 of the drawings, a, a represent a pair of retaining rollers and b, b a pair of drawing rollers. Between the two pairs of rollers there are disposed a pair of laterally spaced side plates 0, c, of suitable depth and of such length and so fashioned at their ends as to extend substantially from the nip of the retaining rollers to that of the drawing rollers. Sideplate c is extended upwards to carry top plate a in the open position. Integral with the side plate 0 is a bottom plate d, and above the sliver and fitting slidably between the side plates is a removable top plate e. This top plate is slidably held to sideplate c when in the open position for threading and is locked to c in the working position by assas spring plungers. Sideplate c has openings in which engage eccentrics g cut on a sleeve which is rotatable on a fixed spindle It. On the same sleeve there are also fast eccentrics g, g which are set at 180 to the eccentrics g and which engage in openings in the side plates c and bottom plate d. By rotation of the eccentrics g, g by means of setting discs such as h fast with the sleeve carrying them, the side plate carrying locked on to it the top plate e may be moved towards or away from the bottom plate d which is integral with side plate 0' and the angle of inclination towards one another and also to the longitudinal centre-line of the sliver can be varied.

In the arrangement shown in Figs. 3 and 4, the side plates c, spaced laterally as in the previously described arrangement, are fixed and the top plate e is shown as being fixedly, but detachably held between them. The bottom plate a is, in this instance, slidable freely between the plates and is yieldingly pressed upwardly against the sliver by means of weight or spring loaded levers h, h pivoted at i, i. If desired, means may be provided for locking either of the levers h or h in a determined position, so that its extremity which bears against the plate a! will form a pivot about which the plate may move angularly when its other end is moved up or down against the action of the lever acting thereon. The arrangement shown in Figs. 1 and 2 may be made yielding in character by replacing the eccentrics g, g, by suitably loaded levers as in Figs. 3 and 4.

Fig. 5 is a longitudinal section showing how the slivercontacting surfaces of the members forming the constricting channel along which the sliver is caused to pass between the nip of the retaining rollers and that of the drawing rollers may be curved or otherwise suitably shaped to obtain the required change of crossasectional area of the sliver determined by the fibre-length distribution in the sliver, the frictional co-efficient of the material being processed, the thickness or diameter of the sliver as it enters and as it leaves the drafting zone and so forth. Fig. 6 is an end view showing how such sliver-contacting surfaces may also be curved or hollowed in cross-section to obtain uniform pressure on the sliver.

If found desirable or advantageous the material constituting the inner face of any of the members employed to form the constricting passage-way may be made flexible to assist in affording the desired fibre control.

Fig. 7 is a side view showing how either the top or the bottom plate, in this instance the top plate may be made in sections longitudinally and if so constructed or arranged each such section may be separately acted upon by pressure-applying means. The two pivots j, i, may be adjustable as to position, and the two sections may be pre-set or they may be capable of displacement by thickness-variations in the sliver.

Fig. 8 is an end view showing how the bottom plate d may be split into sections capable of movement independently to allow for thickness-variations in the sliver. The sections are shown as resting on a common bed k of compressible material, but alternatively separate loading means may be provided for the sections.

The width of the channel formed by the side plates c, c, may be constant along its length or it may increase or decrease.

Fig. 9 shows an arrangement in which the bottomplate is capable of tilting within limits in a transverse direction.

It will be understood that if necessary or desirable for constructional reasons the whole structure constituting the controlling passageway may be turned through 90, so that what I have termed the side plates may be above and below the sliver and what I have referred to as top and bottom plates be on either side of the sliver.

Reference to the sliver is intended to include a plurality of slivers.

If desired, provision may be made for reciprocating the 6 members constituting the constricting passageway laterally across the width of the retaining rollers and drawing rollers. Further the movement of any of yielding members constitutin'g the passageway due to variations in sliver thickness may be arranged to initiate changes in the surface speed and for setting relative to each other of either the retaining rollers or of the drawing rollers.

It will be understood that any of the constructional variations described and illustrated may be combined with each other, not necessarily as shown separately to form one or more embodiments of the invention.

Referring now to Figs. 10 and 11 of the drawings, a represents a bottom front or drawing roller driven by any usual means from the driving mechanism of the machine. In the roller a there is formed a peripheral groove a into which fits a co-operating top roller b, in this case a single wheel on a shaft m carried in the hearings in a frame of 'U-shape, the legs 12, n,- of which are pivoted on fixed studs p whilst the ends of the leg remote from the pivots are connected by a bridge piece n. Fast on the shaft of the roller a is a toothed pinion r the pitch circle diameter of which is substantially equal to the diameter of the base a of the groove in the said roller. With the pinion r there meshes a pinion s fast on the the shaft m, the pitch circle diameter of which pinion is substantially equal to the diameter of the roller b. The frame carrying the shaft in and roller b is loaded towards the roller a by a spindle t having a collar 1' on which there bears a spring a confined between the said collar and the upper end of a spring box v on a frame w pivotal on the studs p. The lower end of the spindle t bears on the bridge member 11' and its action tends to force the roller b downwardly into the groove a in the roller a.

The end of the frame w remote from the pivots p is secured by screws y to a fixed part z. Removal of these screws y permits the roller b to be moved upwardly away from the roller a for cleaning purposes. The sliver is indicated by the broken line 4. The side pieces or checks such as 5, 5, shown as being constituted by downward extensions below the bridge piece n guide the sliver into the groove a.

Scrapers or felt pads 6 and 7 may be provided to keep the rollers a and b respectively free from loose fibres.

In Fig. 12 there is shown an arrangement in which a grooved roller a has two rollers such as b co-operating with it, and in Fig. 13 an arrangement is shown in which a single roller 8 co-operates with two grooved rollers g In Fig. 14 there is shown an arrangement in which both the base of the groove a in the roller a and the surface of the roller b are made concave instead of being flat as in Figs. 10 and 11. Fig. 15 shows one arrangement in which the roller 11 is so mounted on its shaft as to be capable of tilting through a small angle in either direction from its central position. Fig. 16 shows an alternative arrangement to Fig. 15, the roller b being in this case mounted on a bush w of resilient material such as rubber.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

. 1. Means for drafting a fibrous sliver without the use of rotating or travelling means between retaining and drawing rollers, comprising plain top and bottom surfaces which are relatively movable substantially perpendicularly to the sliver axis, and two plain side surfaces equidistant from each other throughout the length of said top and bottom surfaces, said four surfaces forming an uninterrupted passageway which extends as nearly as practicable from thenip of the retaining rollers to the nip of the drawing rollers, and all of said surfaces during drafting being stationary in the direction of travel of the sliver and being in constricting contact with the sliver to act to constrict it to less than its natural cross-sectional area, and said passageway being so positioned that the sliver center-line forms a straight line between the nip-points of the retaining and drawing rollers.

2. Means as defined in claim 1, wherein said surfaces are formed by members which provide a passageway which is closed at any point in its length and produces inter-fibre pressure in the sliver undergoing draft therethrough in a continuous manner from the nip of the retaining rollers to the nip of the drawing rollers, and said surfaces being preset in relation to each other to constrict the sliver to cross-sectional area determinedly less than normal.

3. Means as defined in claim 2, wherein said members comprise a side plate on each side of said passageway and a top and a bottom plate fitting between said side plates, all of said plates cooperating to constrict the sliver to a determined cross-sectional area at all points in its travel from the retaining rollers to the drawing rollers.

4. Means as defined in claim 2, wherein said members comprise a side plate on each side of said passageway and a top plate and a bottom plate fitting between said side plates, and said top plate is adjustable to vary its distance from the longitudinal center of the sliver.

5. Means as defined in claim 2, wherein said members comprise a side plate on each side of said passageway and a top plate and a bottom plate fitting between said side plates, and said top plate is inclined to the longitudinal centerline of the sliver at an angle which is adjustable.

6. Means as defined in claim 2, wherein said members comprise a side plate on each side of said passageway and a top plate and a bottom plate fitting between said side plates, and said bottom plate is adjustable to vary its distance from the longitudinal center-line of the sliver.

7. Means as defined in claim 2, wherein said members comprise a side plate on each side of said passageway and a top plate and a bottom plate fitting between said side plates, and said bottom plate is adjustable to vary its angle to the longitudinal center-line of the sliver.

8. Means as defined in claim 2, wherein said members comprise a side plate on each side of said passageway and a top plate and a bottom plate fitting between said side plates, and the surface of said top plate in contact with the sliver is curved in longitudinal section to change the cross-sectional area from point to point along the length of said passageway.

9. Means as defined in claim 2, wherein said members comprise a side plate on each side of said passageway and a top plate and a bottom plate fitting between said side plates, and the surface of said top plate in contact with the sliver is straight in longitudinal cross-section.

10. Means as defined in claim 2, wherein said members comprise a side plate on each side of said passageway and a top plate and a bottom plate fitting between said side plates, and the sliver-contacting surface of said bottom plate is curved in longitudinal section to change the cross-sectional area from point to point along the length of said passageway.

11. Means as defined in claim 2, wherein said members comprise a side plate on each side of said passageway and a top plate and a bottom plate fitting between said side plates, and the sliver-contacting surface of said bottom plate is straight in longitudinal cross-section.

12. Means as defined in claim 2, wherein said members comprise a side plate on each side of said passageway and a top plate and a bottom plate fitting between said side plates, and the sliver-contacting surfaces of both said top plate and bottom plate are curved in longitudinal section to change the cross-sectional area from point to point along the length of said passageway.

13. Means as defined in claim 2, wherein said members comprise a side plate on each side of said passageway and-a top plate and a bottom plate fitting between said side plates, and the sliver-contacting surfaces of both said top plate and bottom plate are straight in longitudinal cross-section.

14. Means as defined in claim 1, wherein said top and bottom surfaces are formed on members at least one of which is pressed yieldingly against the sliver and is movable by thickness variations in the sliver in a direction substantially perpendicular to the axis of the sliver.

15. Means as defined in claim 1, wherein said top and bottom surfaces are formed on top and bottom members which fit between said side surfaces and at least one of said members is pressed yieldingly against the sliver and is movable by thickness variations in the sliver in a direction substantially perpendicular to the axis of the sliver, said yieldingly pressed member being displaceable by increase in thickness of the sliver at any point along its length and causing increased pressure to be applied to the sliver at such points.

16. Means as defined in claim 1, wherein said top and bottom surfaces are formed on top and bottom members which are composed of adjustable sections and said members are pre-set in relation to each other so as to constrict the sliver to a cross-sectional area determinedly less than normal and to produce inter-fibre pressure in the sliver undergoing draft in a continuous manner from the nip of the retaining rollers to that of the drawing rollers, said surfaces closing said passageway at least partially along its length and extending from the retaining rollers to the drawing rollers.

17. Means as defined in claim 1, wherein said top and bottom surfaces are formed on top and bottom members, one of said members being pivoted on a longitudinal axis which permits said member to rock slightly in response to any transverse variation in sliver thickness across said passageway, said surfaces closing said passageway at least partially along its length and extending from the retaining rollers to the drawing rollers and being pre-set in relation to one another so as to constrict the sliver to cross-sectional area determinedly less than normal and to produce inter-fibre pressure in the sliver undergoing draft in a continuous manner from the nip of the retaining rollers to that of the drawing rollers.

18. Means as defined in claim 1, wherein said top and bottom surfaces are formed on top and bottom members, one of said members having the surface thereof in contact with the sliver concave in transverse cross-section, said top and bottom surfaces and side surfaces closing said passageway partially at least along its length and extending from the retaining rollers to the drawing rollers and being preset in relation to each other so as to constrict the sliver to a cross-sectional area determined less than normal and to product inter-fibre pressure in the sliver in a continuous manner from the nip of the retaining rollers to that of the drawing rollers.

19. Means as defined in claim 18, wherein the surface References Cited in the file of this patent UNITED STATES PATENTS 874,714 Westcott Dec. 24, 1907 1,102,298 Schofield July 7, 1914 Kettley June 3, 1941 (Other references on following page) 9 UNITED STATES PATENTS Killars, Jr. Oct. 28, 1941 Gwaltney et a1. June 22, 1943 Richardson Sept. 3, 1946 Fraser Feb. 21, 1950 5 10 Jackson, Jr. May 6, 1952 Ambler June 9, 1953 Ambler May 18, 1954 FOREIGN PATENTS Great Britain May 7, 1952

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