US3166798A

US3166798A - Textile drafting arrangement

Info

Publication number: US3166798A
Application number: US173212A
Authority: US
Inventors: William P Warthen; Bobby L Pitts
Original assignee: Milliken Research Corp
Current assignee: Deering Milliken Research Corp; Milliken Research Corp
Priority date: 1962-02-14
Filing date: 1962-02-14
Publication date: 1965-01-26
Anticipated expiration: 1982-01-26
Also published as: NL288863A; BE628362A; FR1353111A; CH418192A; GB1017303A; ES285093A1

Description

Jan. 26, 1965 w. P. WARTHEN ETAL 3,166,793

TEXTILE DRAFTING ARRANGEMENT Filed Feb. 14, 1962 3 Sheets-Sheet l INVEN .S WILLIA WAR EN BOBBY .PITTS ATTORNEY Jan. 26, 1965 w. P. WARTHEN ETAL 3,166,798

. TEXTILE DRAFTING ARRANGEMENT I 1 Filed Feb. 14, 1962 3 Sheets-Sheet 2 INVENTORS WILLIA M P. WARTHEN ATTORNEY Jan. 26, 1965 w P, WARTHEN ETAL 3,156,793

TEXTILE DRAFTING ARRANGEMENT 3 Sheets-Sheet 3 Filed Feb. 14, 1962 INVENTORS WILLIA M P. WA RTHEN BOBBY L PITTS ATTOR NE United States Patent 3,166,798 TEXTILE DRAFTING ARRANGEMENT William P. Warthen and Bobby L. Pitts, Spartanhurg,

S.C., assignors to Deering Milliken Research Corporation, Spartanhurg, S.C., a corporation of Delaware Filed Feb. 14, 1962., Ser. No. 173,212 15 Claims. (Cl. 19-245) This invention relates to a textile fiber handling arrangement, and more particularly to an improved apronand-roll-cleaning and fiber-control arrangement employing a single apron in conjunction with a stationary backing element which serves not only to guide the apron and a fiber mass but also as a roll clearing or cleaning means.

According to the present invention, an improved aprontype drafting arrangement is provided which has a number of important advantages and features. Among these advantages and features are included the clearing or cleaning of the apron-supporting roll periphery and the interior of the apron passing about the roll, as well as the clearing or cleaning of the outer surface of the apron and the guiding and controlling of the apron and the fiber mass passing along the fiber-control run of the apron. The embodiments according to this invention may include an apron on either the lower or the upper of two nip rolls in a drafting system, it being preferred that the apron be provided on the upper roll, with the lower roll being engaged only by the fiber-guiding and apron-and-rollcleaning element, in order to provide for more facile assembly and disassembly of the apparatus, inasmuch as the lower roll is normally the drive roll and is fixed in place, whereas the upper roll is a driven roll and is easily removable.

The apparatus according to this invention requires only one apron-and-fiber-control element while providing for both interior and exterior cleaning or clearing and guiding of the apron, as well as clearing or cleaning of both of the associated nip rolls of the drafting assembly. Also, according to the preferred embodiment of the invention, self-threading is eifected through the entire drafting assembly incorporating the invention.

Still other features and attendant advantages will become apparent to those skilled in the art from a reading of the following detailed description of several physical embodiments constructed therewith, taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a fragmentary perspective view of a drafting assembly incorporating one physical embodiment constructed according to the invention.

' FIGURE 2 is a schematic illustration in longitudinal section of the embodiment of FIGURE 1, the fluting on some of the nip rolls being omitted for purposes of clarity of illustration.

FIGURE 3 is an exploded view in perspective of the middle roll and apron section of the embodiment of FIG- URES l and 2.

FIGURE 4 is an inverted view in perspective of the clearing and guiding element associated with the top middle roll of the arrangement of FIGURE 1.

FIGURE 5 is a fragmentary longitudinal section view in enlarged proportion, illustrating the fiber-flow path portion of the middle roll section of the drafting arrangement of FIGURE 1, without a fiber mass therein.

FIGURE 6 is a fragmentary longitudinal section view similar to FIGURE 5, illustrating the passage of a fiber mass between the middle rolls and associated apron and clearing and guiding elements.

FIGURE 7 is a schematic longitudinal section view of an alternative embodiment of a drafting arrangement incorporating the invention.

FIGURE 8 is a fragmentary perspective view of the middle roll and apron portion of the drafting arrangement of FIGURE 7.

FIGURE 9 is a fragmentary longitudinal section view of the middle roll portion of the drafting arrangement of FIGURE 7, showing in enlarged and more detailed view the passage of a fiber mass through this portion of the apparatus.

FIGURE 10 is an exploded View in perspective of the middle roll and associated apron and clearing and guiding elements of the arrangement of FIGURE 7.

Referring now in detail to the figures of the drawings, in the embodiment of FIGURES l-6, the invention is illustrated as applied to a drafting assembly having back nip rolls 11, 13,

middle rolls

15, 17, and

front rolls

19, 21, each of the succeeding pairs of rolls being driven at increasing speeds, as by application of a drive force through gearing or the like (not shown) to one roll of each of the pairs of rolls, as for

instance rolls

13, 17, and 21, in order to provide the desired degree of drafting of a fiber mass F (see FIGURE 2). As in the conventional spinning frames, the fiber mass may be twisted and formed into a yarn after exit from between the

rolls

19, 21 or if more drafting is desired, a further drafting assembly may be employed, either duplicating the illustrated arrangement or otherwise as may be desired.

According to the present invention, the

middle roll pair

15, 17 has associated therewith a single apron 23 which may pass about either of the

rolls

15 or 17, such being illustrated in the embodiment of FIGURES 1-6 as being guided about and driven by the bottom roll 17. In lieu of the conventional nose bar which is normally disposed at a spaced position between the middle roll 17 and the front roll 21 for the purpose of guiding the apron through a reduced radius curvature, the present invention utilizes a combination function element 27 which serves not only 1 to guide the apron through a reduced radius reversed cleaning or clearing the contacted apron-carrying pcripheral surface of the roll 17. To this end, the clearing and guiding element 27 preferably is formed of a single block of material having a roll-engaging concave curvature 27 preferably substantially complementary to the curvature of boss 17a of the roll 17 and is tapered therefrom to a reduced radius nose end 27c about which the apron passes to formits tapered radius nose path of travel. Along the fiber-control path 23b of the apron between the roll 17 and the nose end 27c of the element 27, the clearing and guiding element is provided with an apron-guiding surface which materially aids in the control function of the apron along this path, particularly by reducing the tendency of the apron to buckle in this zone and by aiding in guiding the apron in a predetermined path of travel along this fiber-control zone. This apron-guiding surface 27d is illustrated as substantially straight, butmay be curved either convexly or coneavely in some instances. Not only does the guide surface 27d of the element 27 serve to guide and aid in the control of the apron on the fiber mass passing thereby, but also this surface serves in conjunction with the tapered nose end 27c and return surface 27r to keep the interior surface of the apron substantially clean of lint, both by the rubbing action of the apron thereover and by the substantial tendency to prevent lint from entering the zone within the apron. Any lint or other foreign matter which may in some manner 5 get inside the apron periphery will quickly be rubbed off and will either fall out of the system or be ground to a very fine and insignificant dust between the roil 1? and the adjacent concave surface 27, of the element 27 during the normal rotational movement of the roll 17. As a matter of fact, the grinding of some fibers to a fine dust in this manner is believed to be beneficial to the passage of-the apron about the element 27 and roll 17, due perhaps to the lubricating qualities of the ground particles. Such ground dust particles are, however, prevented from being built up on the interior surface of the apron through the rub-cleaning action of the element 27011 the apron interior as the apron passes along its various runs in engagement therewith.

Serving in conjunction with the single apron 23 and its associated clearing and guiding element 27 is a further clearing and guiding element 25 about which no apron passes, but which element 25 engages with both the middle roll 15 and the exterior surface of the fibercontrol run 23b of the apron 23. This additional element 25 is connected to the element 27, preferably removably, as through the medium of a removable connecting pin 29 which may pass through complementary openings 2% and ears 25a formed on opposite lateral sides of the element 25, and a complementary bore 2% extending laterally through the element 27. in order to obviate any tendency of the movement of the single apron 23 to imparta clockwise movement of the

elements

25 and 27 about the axis of roll 17 vdue to the unbalanced torque exerted on the

elements

25 and 27 by the movement of the apron 23, there is provided in this embodiment an anchor wire 31 which has an arm 31a removably extending through a complementary bore 251' formed in the element 25, and a hook or bend 311) which extends removably in anchored relation over one of the fixed cross back bar elements 41 of the support frame of the spinning machine or the like and holds the rod under tension tohold the element 25 in compression against the roll 15.

Lateral stabilization of the

elements

25 and 27 may be effected-as by providing side lips or shoulders on one or

bothofthe elements

25 and 27 for engagement with the opposite-endsof the boss portion of the respectively-engaged

rolls

15 and 17. In the illustrated embodiment the elcment'27 is provided with such concave shoulders 27a (see FIGURE 3) which loosely fit about the opposite longitudinal-ends of the knurled raised boss portion 17a of the drive roll 17 so as to provide the desired degree of lateral stability .to the system.

Referring again to the external cleaning and guiding element 25, we have found it most desirable that this element be formed with a chamfered or curved back surface 25h adjacent its respective roll 15, particularly in order'to permit the passage of fiber mass variations between this surface and the adjacent outer peripheral surface of the apron 23, as shown more particularly in FIG- URES 4-6. Also, it has been found that in order to afford the normally desired high degree ofsuccess in selfthreadup of'the fiber mass F as it passes through this portion of-the drafting apparatus it is desirable to form the element '25 with an undercut 25i so as to provide a clear space of approximately .010" to .030" depth and A1"- A' arc length between the periphery of roll 15 and the element 25 at the zone of fiber exit from the roll 15 and entry between the element 25 and apron 23. The exact mode of operation of this undercut 25a is not known, however it is of considerable aid in increasing the percentage of self-feedthrough of fibers between the apron and guide element 25. One theory of its operation is the prevention of entrapment of fibers between the roll 15 and the element 25, particularly at the time of threadup when the free feeding end of the fiber mass F may have a tendency to bunch up at the entrance to the zone be tween element 25 and apron 23.

Further, in order to accommodate the passage of the fiber mass through the zone between the element 25 and d .pron 23 it is, of course, necessary that the

interfacing uriaces

25g and 27d of the two

elements

25 and 27 be sufiiciently spaced apart to accommodate the passage of the fiber mass between the apron and the guide surface of element 25, as shown particularly in FlGURES 5 and 6.

it wili be appreciated that the clearing or cleaning and guiding element 25 not only serves to clear or clean the peripheral surface of the roll 15, but also serves in conjunction with the apron 2:3 and the element 27 to guide and control the passage of the fiber mass in the zone between the

rolls

15, 17 and

front rolls

19, 21, and the additional function of clearing the outer surface of the apron 23 by the rubbing contact of the apron with the fibercontrol run engaging surface 25g.

Tiers is shown a preferred modification of a single apron clearing and guiding arrangement according to the invention in FIGURES 7-10. in this embodiment, as in FIGURES 16, the single apron 123 and associated clearing and guiding

elements

125, 127 are illustrated as applied to the

middle roll pair

15, 17 of a three-pair drafting assembly. However, in this preferred embodiment the apron 123 passes about the top roll 15, rather than the bottom roll 1'7, and this provides an important practical advantage in that the top rolls are normally arranged in removable pairs for each two side-by side drafting positions, whereas the bottom roll serves as the drive roll and extends over the entire length of the frame. Thus, in this embodiment the element 125 corresponds to the element 27 o FIGURES 1-6 in overall general function and the element 127 corresponds to the element 25 of FIGURES l-6 in overall general function.

Thus, in this modified embodiment the element 127 is provided with a fiber-control and apron-clearing surface 127a which is chamfered or curved back as indicated at 1271 1. at the beginning end thereof. Also, this element 12'? is formed with an undercut 1271 providing a small clearance space between the roll 17 and the element 127 of a distance of from approximately /8 to /4 inch adjacent the entry point of the fiber mass between the element 127 and the apron 123.

The two

elements

125 and 27 are removably secured together and positioned with respect to one another through the medium of cars 125a formed on the element 125 and which have detent-receiving recesses 125m formed on the interfaces thereof, with the element 127 having complementary raised detents or nodules 127k formed on each of its opposite lateral sides for removable interengagement with the recesses 125m. The element 127 preferably has shoulders 127t formed thereon for engagement with the rear surfaces 125t of the ears 125a as a further aid to establish the relative positions of the two

elements

125 and 127 and to prevent any material undesired rocking of one or both of the elements about the pivot formed by the detent and recess connection 127k, 125m.

In this embodiment lateral stability is provided for the two

elements

125 and 127, and thereby for the apron 123, through the medium of lateral shoulders 127a which engage in a loose fit about the opposite longitudinal ends of the raised, preferably smooth-surfaced boss portion 17a of the roll 17.

Torsional stability is imparted to the

elements

125, 127 in this embodiment by forming a concave extension 127 on the element 127, which extension extends through an extent of greater than about the roll 17, thereby providing a snap action fit of the element 127 onto the boss 17:: of the roll 17. By thus anchoring the element 127 to the roll 17 a sufiicient resistance is provided to prevent the torsion imparted to the system by the movement of the apron 123 from rotating the

elements

125 and 127 counterclockwise with the apron and about the axis of roll 15. Also, by providing this cup-type snap action fit of the extension 127j on element 127 it will be appreciated that the element 127 need not be held as tightly against the roll 17 as may in some occasions be exerted by the element 25 on the roll when employing a stabilizing wire 31 as in the first-described embodiment. In this embodiment of FIGURES 7-10 the entire concave surface 127s thus not only serves to clear or clean the peripheral surface 170 of the roll 17, but also serves to secure the element 127 onto the roll in snap-action removable manner. Various materials may be employed to permit such snap-action operation, it being preferred to form both of the

elements

125 and 127, as well as elements .25 and 27 of FIGURES 16 of plastic material, such as Delrin, nylon, Teflon, etc., due particularly to the low cost of forming and provision of the more desirable qualities of stability, resilience, and relatively low coeflicient of friction. However, various other materials, such as wood, metal, Micarta, Bakelite, may be employed in some instances, if desired.

While the invention has been described with respect to two physical embodiments constructed in accordance therewith, it will be understood by those skilled in the art that various modifications may be made therein without departing from the scope and spirit of the invention. Accordingly, it is to be understood that the invention is not to be limited by these specific illustrative embodiments, but only by the scope of the appended claims.

That which is claimed is:

1. A drafting arrangement comprising a pair of closely adjacent draft rolls forming a nip zone therebetween and a single fiber-guiding apron passing over one roll of said pair of rolls and being of materially larger circumference than said one roll of said pair of rolls, a combination roll-and-apron-clearing and apron-supportingaand-guiding element engaging the apron-carrying periphery of said one roll of said pair of rolls and the interior surface of said apron, and a second roll-engaging element engaging a portion of the periphery of said other roll of said pair of rolls, said two elements each having a fiber-guiding surface facing one another and extending away from the nip zone of said rolls, said apron being carried about said roll-and-apron-clearing and apron-supporting-and-guiding element and said one roll of said pair of rolls and between the respective two said fiber-guiding surfaces on said two elements, said apron being engageable with and guided by each of said two fiber-guiding surfaces for guiding and controlling the passage of a fiber mass passing between and in engagement with said apron on the one hand and the other roll of said pair of rolls and said fiber-engaging surface formed on said second roll-engaging element on the other hand, said second roll-engaging element being spaced from said roll periphery at the entry zone of the fiber mass between said second element and said apron along at least the central fiber-flow-path portion of said second element, for aid in passage of fibers between said second element and said apron through minimizing of lap up on said other roll of said pair of rolls.

2. A drafting arrangement according to claim 1 wherein one of said elements has shoulder means formed thereon and engageable with longitudinally spaced portions on one of said rolls for restricting lateral movement of said element along the longitudinal extent of said rolls and thereby establishing the operating position of said said one element with relation .to the longitudinal extent of said rolls.

3. A drafting arrangement according to claim 1, wherein said one roll of said pair of rolls and associated rolland-apron-clearing and apron-supporting-and-guiding element is disposed beneath the other roll of said pair of rolls and said second roll-engaging element.

4. A drafting arrangement according to claim 1, said other roll of said pair of rolls being a common drive roll for several side-by-side spinning positions, said one roll of said pair of rolls and associated roll-and-apron-clearing and apron-supportingaand-guiding element being disposed above the other roll of said pair of rolls and said second roll-engaging element, to facilitate ease of assembly and 6 disassembly of said apron and said clearer elements in relation to said rolls and to eliminate necessity for removal of said apron from said drive roll.

5. A drafting arrangement comprising a pair of closely adjacent draft rolls forming a nip zone therebetween and a single fiber-guiding apron passing over one roll of said pair of rolls and being of materially larger circumference than said one roll of said pair of rolls, a combination roll-and-apron-clearing and apron-supporting-and-guiding element engaging the apron-carrying periphery of said one roll of said pair of rolls and the interior surface of said apron, and a second roll-engaging element engaging the periphery of said other roll of said pair of rolls, said two elements each having a fiber-guiding surface facing one another and extending away from the nip zone of said pair of rolls, said apron being carried about said roll-and-apron-clearing and apron-supporting-and-guiding element and said one roll of said pair of rolls and between the respective two said fiber-guiding surfaces on said two elements, said apron being engageable with and guided by each of said two fiber-guiding surfaces for guiding and controlling the passage of a fiber mass passing between and in engagement with said apron on the one hand and the other roll of said pair of rolls and said fiber-engaging surface formed on said second roll-engaging element on the other hand, and means for holding said second rollengaging element in engagement with the periphery of said other roll of said pair of rolls.

6. A drafting arrangement according to claim :5 wherein said holding means includes a rod connected between said second roll-engaging element and a support spaced from the connecting point of said rod to said second roll-engaging element.

7. A drafting arrangement according to claim 6 wherein said other roll of pair of rolls is disposed between said second roll-engaging element and said support.

8. A drafting arrangement according to claim 7 wherein said support is a stationary back bar, said rod including a bend which passes over said back bar and maintains said rod under tension to thereby hold said second roll-engaging element under compression against its associated said roll.

9. A drafting arrangement according to claim 5 wherein said holding means includes a roll-engaging extension on said second roll-engaging element and being adapted to wrap around said other roll of said pair of rolls to the rear-most side thereof opposite to the side on which the fiber-engaging surface thereof is disposed.

10. A drafting arrangement according to claim 9, said extension is integral with said second roll-engaging element, said extension having at opposite lateral sides thereof a pair of shoulders for engagement with said other roll of said pair of rolls to aid in lateral positioning of said second roll-engaging element, said two elements being interconnected and restrained against material relative movement along a lateral direction extending along the longitudinal extent of said rolls whereby both of said elements are laterally positioned by said shoulders.

11. A drafting arrangement comprising a pair of closely adjacent draft rolls forming a nip zone therebetween and a single fiber-guiding apron passing over one roll of said pair of rolls and being of materially larger circumference than said one roll of said pair of rolls, a combination rolland-apron-clearing and apron-supporting-and-guiding element engaging the apron-carrying periphery of said one roll of said pair of rolls and the interior surface of said apron, and a second roll-engaging element engaging the periphery of said other roll of said pair of rolls, said two elements each having a fiber-guiding surface facing one another and extending away from the nip zone of said rolls, said apron being carried about said roll-and-apronclearing and apron-supporting-and-guiding element and said one roll of said pair of rolls and between the respective two said fiber-guiding surfaces on said two elements, said apron being engageable with and guided by each of saidtwo 'fibersguiding surfaces for guiding and controllingathe passage of a fiber mass passing between and in engagement with said apron on the one hand and the other roll ofsaid'pair of-rolls and said fiber-engaging surface .forrned on said second roll-engaging element on the other hand, said fiber-guiding surface on said second rolengaging element is formed with a convex bend of its fiber-guiding surface adjacent said other roll of said pair of rolls-to aid-in guiding a running length of fibers toward and along'said apron, said fiber-guiding surfaces formin a fiber-and apron-guiding throat zone which is most open at its tiber'inputend'for aid in fiber passage and control.

12. A drafting arrangement comprising a pair of nipforrning'rolls, a single apron about only one roll of said pair- 0f rolls and'having a fiber-niass-engaging-andguiding run, an apron-guiding element having a nose portion spaced from one of said rolls of said pair of rolls and engaging the interior surface of said apron, at an apron path'reversal 'zone'and a roll-engaging element disposed exteriorly of said apron and engaging the other roll of said :pair of rolls, said roll-engaging element having a fiber-mass-engaging-and-guiding surface disposed adjacentxand facing said fiher-mass-engaging-and-guiding run ot'said apron, said roll-engagingelement engaging a portion oftheperiphery of the other roll of said pair of rolls and is spaced r'rorn the periphery of the other roll of said pair of rolls at the entry zone of the fiber rnass along at least the central fiber-floW-path portion of said rollengaging element, for aid in passage of fibers between said roll engaging element and said apron through minimizing of lap up on said other roll of said pair of rolls.

13. A drafting arrangement comprising a pair of nipforniing rolls, a single apron engaged by and passing between both of said rolls and about one roil of said pair of rolls, an apron-Vand-roll-engaging-and-clearing element disposed Within said apron and engaging in clearing relation with both the periphery of said one roll of said pair of rolls and the interior surface of said apron and an apron-clearing second element engaging with the outer surface of said apron for guiding of fibers passing along said apron outer surface and for c earing of said apron outer surface, said apron-clearing second element engaging in clearing reiation With both the external surface of said apron and the fiber engaging periphery of the other roll of said pair of rolls.

14. A drafting arrangement according to claim 13 including an interconnection between said two clearing elements, said interconnection serving to space the apronengaging portions of said elements apart for passage of apron and fibers to be drafted therebetween, means for holding said apron-clearing second element in engagement with the other roll of said pair of rolls, and said interconnected clearing elements themselves form a cradle for said apron, without necessity for a further exte ri cradle support.

i A drafting arrangement comprising a pair of nipforming rolls, a single apron about only one roll of said pair of rolls and having a fiber-mass-engaging-and-guiding run, a first apron-guiding element having a nose portion spaced from said one roll of said pair of rolls and engaging the interior surface of said apron at an apron path revcrsal zone, and a roll-engaging clement disposed exteriorly or" said apron and engaging the other roll of said pair of rolls, said roll-engaging element having a fiber-1nass-engaging-andguiding surface disposed adjacent and facing said fibe--massengaging-and-guiding run of said apron, said roll-engaging element having an un' erczrt portion spaced from said other ro'il of said pair of rolls at the fiber input end thereof and contiguous to said fiher-niassengaging-and-guiding surface thereof, said other roll of said pair of rolls having a smooth surfaced apron-and-fiber-engaging periphery.

liieierences Qited in the file of this patent UNITED STATES PATENTS 1,254,390 Casablancas clan 22, l9l8 1,448,19i Butler Mar. 13, 1923

Claims

1. A DRAFTING ARRANGEMENT COMPRISING A PAIR OF CLOSELY ADJACENT DRAFT ROLLS FORMING A NIP ZONE THEREBTWEEN AND A SINGLE FIBER-GUIDING APRON PASSING OVER ONE ROLL OF SAID PAIR OF ROLLS AND BEING OF MATERIALLY LARGER CIRCUMFERNCE THAN SAID ONE ROLL OF SAID PAIR OF ROLLS, A COMBINATION ROLL-AND-APRON-CLEARING AND APRON-SUPPORTING-AND-GUIDING ELEMENT ENGAGING THE ARPON-CARRYING PERIPHERY OF SAID ONE ROLL OF SAID PAIR OF ROLLS AND THE INTERIOR SURFACE OF SAID APRON, AND A SECOND ROLL-ENGAGING ELEMENT ENGAGING A PORTION OF THE PERIPHERY OF SAID OTHER ROLL OF SAID PAIR OF ROLLS, SAID TWO ELEMENTS EACH HAVING A FIBER-GUIDING SURFACE FACING ONE ANOTHER AND EXTENDING AWAY FROM THE NIP ZONE OF SAID ROLLS, SAID APRON BEING CARRIED ABOUT SAID ROLL-AND-APRON-CLEARING AND APRON-SUPPORTING-AND-GUIDING ELEMENT AND SAID ONE ROLL OF SAID OF ROLLS AND BETWEEN THE RESPECTIVE TWO SAID RIBER-GUIDING SURFACES ON SAID TWO ELEMENTS, SAID APRON BEING ENGAGEABLE WITH AND GUIDED BY EACH OF SAID TWO FIBER-GUDING SURFACES FOR GUIDING AND CONTROLLING THE PASSAGE OF A FIBER MASS PASSING BETWEEN AND IN ENGAGEMENT WITH SAID APRON ON THE ONE HAND AND THE OTHER ROLL OF SAID PAIR OF ROLLS AND SAID FIBER-ENGAGING SURFACE FORMED ON SAID SECOND ROLL-ENGAGING ELEMENT ON THE OTHER HAND, SAID SECOND ROLL-ENGAGING ELEMENT BEING SPACED FROM SAID ROLL PERIPHERY AT THE ENTRY ZONE OF THE FIBER MASS BETWEEN SAID SECOND ELEMENT AND SAID APRON ALONG AT LEAST THE CENTRAL FIBER-FLOW-PATH PORTION OF SAID SECOND ELEMENT, FOR AID IN PASSAGE OF FIBERS BETWEEN SAID SECOND ELEMENT AND SAID APRON THROUGH MINIMIZING OF LAP UP ON SAID ROLL OF SAID PAIR OF ROLLS.