US3878997A

US3878997A - Doffable bobbin assemblies

Info

Publication number: US3878997A
Application number: US460065A
Authority: US
Inventors: Samuel F Adams; Robert J Guerin
Original assignee: AMERICAN PAPER TUBE CO
Current assignee: AMERICAN PAPER TUBE CO
Priority date: 1974-04-11
Filing date: 1974-04-11
Publication date: 1975-04-22
Anticipated expiration: 1992-04-22

Abstract

In the high-speed winding of textile yarns and the like, high levels of driving torque, and accurate maintenance of bobbin positions after prolonged use, and mechanical freedoms which promote ease of doffing, are all promoted by bobbin structure wherein an internal seat near the upper end of the bobbin has a degree of taper about one-third greater than that of a cooperating spindle tip on which it is to be suspended and driven, and wherein that taper of the internal bobbin seat does not extend beyond a prescribed very small distance below the site at which the bobbin and spindle tapers meet.

Description

United States Patent Adams et al.

[ 1 Apr. 22, 1975 1 DOFFABLE BOBBIN ASSEMBLIES 3.167.262 l/l965 Adams et al. 242/4621 7 [75] Inventors: Samuel F. Adams, Greenville; Jr.: 24324232617 Robe" J Guerin, Providence. both .7 of Primary E.\'aminer-Stanley N. Gilreath [73] Assignee: American Paper Tube Company, Attorney, Agent. or Firm-James E. Mrose Woonsocket, R1.

[22] Filed: Apr. ll, 1974 [57] ABSTRACT [21] App]. No.: 460,065 In the high-speed winding of textile yarns and the like,

high. levels of driving torque, and accurate mainte- 7 nance of bobbin positions after prolonged use, and C I llllllllll 242/4621 hzgfl l 'i mechanical freedoms which promote ease of doffing. [58] Fie'ld 46 2 46 3 are all promoted by bobbin structure wherein an inter- 242/46 4 1 l8 3 1 nal seat near the upper end of the bobbin has a degree 1 6 of taper about one-third greater than that of a cooperating spindle tip on which it is to be suspended and [56] Rderenccs Cited driven, and wherein that taper of the internal bobbin seat does not extend beyond a prescribed very small UNITED STATES PATENTS distance below the site at which the bobbin and spin- Z.497.834 2/1950 Kennedy 242/4611 dle tapers mee[ 2.615.650 l0/l952 Bctner et al...... 242/4621 X 2.922.274 l/ I960 Sacchini 242/462]. X 8 Claims, 3 Drawing Figures 5 |0 lb! 2' 1 ,IS

l a e 3 I e l 22 l DOFFABLE BOBBIN ASSEMBLIES BACKGROUND OF THE INVENTION The present invention relates to improvements in supports, for textile yarn and like materials, which are to be wound at high speeds with adequate driving torque while remaining well seated and lending themselves to automatic or manual doffing with relatively light force, and, in one particular aspect, to novel and improved assemblies of the type wherein a lightweight tubular bobbin is intended to be rotated by a spindle having a small external taper near its upper end, the bobbin being provided with a cooperating internal seat the mating surfaces of which have about a one-third greater taper than that of the spindle tip and which fully clear the spindle crown to avoid force components which would cause rising, and the internal bobbin seat surfaces extending no more than a predetermined short distance below the site at which the spindle tip makes engagement with them.

As is well known in the textile machinery art, packages of yarn or other textile threads are commonly collected upon spindle-mounted tubular cores or bobbins for further processing and dispensing, it being important that such bobbins be of predetermined external dimensions and have smooth surface characteristics, that they be of relatively light weight and inexpensive, and that they lend themselves to rotation and collection of yarn at very high speeds without attendant yarn breakages, slippage. shifts in position, or excessive seat wear. The bobbin and spindle assemblies which have evolved over the course of many years in this well-developed art have assumed a variety of structural forms and have been fabricated of many different materials; however the type of assembly to which the present invention is particularly directed involves a generally tubular bobbin which is mated rather loosely with an associated upright spindle over substantially its full length and is slipfitted in a frictionally driven relationship with the spindle near its upper end. Commonly, such bobbins are slightly tapered, or conically sloped, and may be made of impregnated paper, wood or plastic. Large numbers of these are dropped empty, onto numerous upstanding spindles of a winding machine, after a few turns of yarn have first been wrapped manually or automatically around the base or acorn position of each of the spindles, and the spindles are then rapidly accelerated to the very high rotational speeds which are modernly required for heightened productivity. Package build-up on each bobbin is conventionally regulated by a surrounding movable ring-traveller, which is designed to have the yarn pulled through it at an optimum angle. In certain prior designs, the bobbin drive by the rotating spindle mechanism has been mechanically positive, through clutching, and spring-clamping or interfitting clutch projections and slots have been resorted to in efforts to prevent slippage. However, such positive-drive mechanisms quickly tend to accumulate lint and other contaminants which not only require frequent cleaning but also interfere with proper seating and doffing, and such mechanisms also tend to be undesirably costly and complex. For such reasons, simple friction-drive mechanisms have gained widespread acceptance, even though these can also lead to certain problems such as those associated with rapid wear, drive-slippage, seatjamming, hard doffing, and rising or jumping-up of the bobbins at high speeds. In one common arrangement of the friction-drive type, a tapered spindle tip mates securely with a corresponding tapered seat on the interior of the bobbin; in another, the jamming tendencies of such taper-to-taper fits are avoided through use of a universal-type joint in which the rounded tip of the spindle cooperates with a bobbin seat making a substantially line-contact engagement with the spindle tip. The latter form ofline-contacting drive advantageously avoids locking or freezing which can impede doffing, but is subject to slippage and is particularly susceptible to wear which then allows the bobbin to drop further down upon the spindle than it should for optimum operation. Small-area contacting likewise tends to develop intense localized heating which quickly deteriorates the bobbin seat and therefore prevents successful use of heat-susceptible plastics and the like.

SUMMARY In accordance with the present teachings, difficulties of the aforesaid character can be significantly reduced through-critical and yet relatively simple and inexpensive structural innovations in the seating provisions for bobbins of the type which are to mate with tapered spindle tips, and, in particular, low-force doffing is promoted. These innovations are in part concerned with efficient drive and support of a bobbin by way of internal seating which has a taper which is a prescribed amount greater than that of the spindle tip with which it mates, and which has prescribed axial lengths; collaterally, the provisions of close-fitting guide and shoulder surfaces below the bobbin seat aids in regulating optimum seating upon the spindle.

It is one of the objects of the present invention, therefore, to provide novel and improved internally driven textile bobbins of low-cost and uncomplicated construction which are proportioned to fit with drive spindles for efficient reception of drive torques and yet which are readily doffable.

A further object is to provide unique textile bobbins of the internally driven type intended for use with tapered-tip spindles and which are effectively protected against doff-resisting jamming by certain controlled restraints imposed by internal seat surface and brought into play during donning operations.

By way of a summary account of practice of this invention in one of its aspects, an elongated tubular paper bobbin member of generally conventional exter nal configuration is adapted to seat with and be driven efficiently at high speeds by the slightly tapered conical outer surfaces near the tip of an upstanding spindle. On its interior, near its upper end, the bobbin surfaces are tapered conically also, the taper, in inches per inch of axial length, being substantially one-third greater than that of the spindle tip in the same direction, such that the tapered internal bobbin surfaces engage with the tapered spindle tip surfaces while remaining completely out of engagement with crown surfaces of the spindle. lmportantly, the axial length or span" of the aforementioned internally-tapered bobbin seating surfaces extends only for an unusually short distance below the crowned tip of the mated spindle, a distance of only up to about 9/32 inch being typical for the improved bobbin, in relation to a conventional 1 H16 inch length for the tapered tip of the cooperating spindle. This short effective length of the bobbin seat serves to avoid undue frictional drag on the bobbon as it is donned onto the close-fitting spindle. thereby also avoiding imperfect seating of the bobbin onto the spindle, and it also prevents the close taper-to-taper fit between the bobbin seat and spindle tip from deteriorating into an undesirably broad-area and tight fit as wear occurs. Above the site where the bobbin seat engages the tapering end surfaces of the spindle, the internal bobbin surfaces are everywhere well removed from the crown surfaces of the spindle, even when the seated bobbin is tipped or skewed slightly due to rocking or vibrational movements such as occur during highspeed rotation; for the latter purposes, the bobbin seat taper angle is kept larger than the angles of tangents to the crown surfaces, such that the crown and bobbin-seat surfaces cannot engage one another even under the worst conditions. Absenting such engagements, the normal impacting or vibration of the bobbin in relation to the lower part of the spindle has a desirably lessened tendency to cause the bobbin to rise or jump up from its properly seated relationship with the spindle due to fulcruming effects. Our US. Pat. No. 3,l67,262 is concerned with the desirable results obtainable through controlled or limited vibrations, which in turn aid in suppressing larger and more harmful vibrations, and the present improvements further contribute to stable operation while nevertheless allowing the desired pivoting actions and low-level vibrations to take place. Spindle tips having relatively large tapers (i.e., in excess of about 0.066 inch per inch) tend to seat tightly with the bobbin seats having the one-third greater taper prescribed herein, because the bobbins need only move a short axial distance to bind securely with the spindles, and, in such instances, the aforementioned short-light bobbin seat is caused to exhibit a shoulder, at its lower end, serving to engage the spindle crown and halt excessively hard seating as the bobbin is dropped onto the spindle during donning operations. Similarly, or in conjunction with such shouldering, relatively close-fitting interior lining surfaces may be provided below the bobbin seat and will serve to interface with excessively forceful seating, for the same reason. On donning of the bobbin, the spindle cannot as a practical matter avoid hitting against the shoulder and/or scaping against the lining surfaces and thereby restraining the dropped bobbin from lodging itself in a jammed seated condi tion which would impede later efforts to doff the bobbin. These lining surfaces, below the seat, are also of sufficiently larger diameter than the seat surfaces to preclude the possibility that the spindle tip would accidentally and improperly seat upon them.

BRIEF DESCRIPTION OF THE DRAWING Although the features of this invention which are considered to be novel are set forth in the appended claims, further details as to preferred practices of the invention, as well as the further objects and disadvan tages thereof, may be most readily comprehended through reference to the following description taken in connection with the accompanying drawings, wherein:

FIG. I is a partly cross-sectioned side view ofa mated high-speed bobbin and spindle assembly incorporating improvements of the present invention;

FIG. 2 represents enlarged fragments of the assembly of FIG. I, at the upper site of seating and at the lower site of a vibration-suppression insert; and

FIG. 3 graphically portrays the optimum relationships between cooperating tapers of bobbin seats and spindle tips.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus appearing in FIG. 1 includes a spindle structure ofa known type wherein a substantially cylindrical elongated metal spindle shaft 5 is rotated about a vertical axis 6-6 on support bearings (not shown) carried upon the usual textile spinning frame with which such spindles are customarily associated. Near its lower end, the spindle is driven at high speeds by way of a whorl 7, and, at its upper end or tip, the rotatable spindle has a tapered frustro-conical seating portion 8 capped by a rounded crown portion 9. Seating portion 9 forms a surface onto which may be fitted the inner seating surface of a bobbin 10, the latter being a laminated resin-impregnated tubular paper bobbin, for example, and including the usual metal end caps 11 and I2. Ordinarily, the internal seating surface of the bobbin would perhaps have a configuration generally complementing that of the spindle seat 8, such that there would be a substantially true taper-to taper or ball-andsocket type fit, with resulting optimum coupling of drive torques from the spindle to the bobbin. Because such taper-to-taper fitting unfortunately tends to cause the bobbin to lock there with the spindle, and thus impair subsequent doffing, the spindle tip would at least be rounded and the bobbin inner seat would be shaped to make an essentially line-type small-area contact with the spindle tip. In the latter type of construction, the relatively sharp seat edge needed to form a line contact is highly troublesome because it wears quickly and because it necessarily allows slippage and consequent generation of heat. Even a relatively small amount of wear, on the bobbin seat or on the spindle itself, will cause the bobbin to rest lower on the spindle than is intended for proper yarn-package build-up, and the tendency toward generation of localized high temperatures make the use of plastics impractical. Moreover, line-contacting assemblies evidence a notorious tendency to reject or raise the bobbins from their seats. By way of important distinction, the bobbin 10 has an internal tapered seat 13, part of which has a frustoconical configuration over the dimensioned distance 14 (FIGS. 1 and 2), the slope or taper being such that the seat narrows inwardly in the upward direction. The upper part of the internal bobbin seat 13 necessarily is of an inner diameter 15 which is less than the upper outer diameter of the spindle seat 8, such that the two seats will necessarily engage near the tip of the spindle seat. However, the bobbin seat has the aforementioned inward narrowing in the upward direction, and critically, the taper or magnitude of such narrowing is selected to be substantially one third greater, in inches per inch, than that of the spindle seat 8. This different taper-totaper relationship results in some minute tapering space 16 (FIG. 2) appearing betwen the two seats below their site of engagement. In preferred improved internal seat constructions for bobbins twelve inches long overall, the internal tapering from bottom to top over the length 14 of the internal bobbin seat 13, has been 0.272 inch/inch, for use with an ll/l6 inch long spindle tip seat 8 having an internal tapering of 0.200 inch/inch, from bottom to top. That particular difference in tapers, which is substantially one-third greater for the bobbin seat-taper, results in a desired optimum area of contacting between the mated surfaces of the spindle seat and the bobbin seat, and, at the same time, leaves lower clearance 16 which promotes easy doffing by off-setting tendencies of the seats to jam or lock together. When the tapered bobbin seat surface has the aforesaid one-third greater taper than that of the mating spindle seat, the area of contacting turns out to be highly satisfactory in terms of the resulting clutching and driving actions and also wearresistance and susceptibility to overheating. Although it is likewise true that a commonplace full taper-totaper fit would offer similar advantages, such a fit proves to be seriously deficient in other respects. and particularly because of locking or sticking actions which interfere with ease of doffing the bobbins once they have been fitted and driven.

In determining the aforementioned important relationship between bobbin-seat and spindle tapers (specifically, the former being substantially one-third greater than the latter), three factors were dominant, and all three were required to be well satisfied before needs of the intended users could be said to be met properly. The first of these concerned the aforementioned degree ofjamming or sticking between the bobbin and the spindle; this factor affects the speed, rhythm and ease with which manual or reliable automatic doffing can be achieved, inasmuch as some automatic doffing equipment may afford no more than about four pounds of lift force and because much higher lifting forces can be expected to induce strain and fatigue of human attendants. For purposes of related evaluations, bobbins were dropped onto stationary spindles from a fixed height of about 4-to-5 inches, and the resulting break-away" forces needed to unset the bobbins from the spindles were considered to be totally unacceptable if found to be twenty or more pounds, as measured by a spring scale. A 6-pound break-away force was considered preferable. The second test factor involved evaluations related to seat driving torques, which are of course significant in that the bobbins must be positively driven smoothly and without excessive slippage if they are to collect yarns rapidly and without breakage and without generating excessive heat at the sites of their seats. For purposes of these evaluations, the bobbins were similarly dropped onto free spindles and then lifted by their tips to determine whether the 3-to-4 pounds spindle structures would be held by the bobbins; if not so held, experience indicates that the drive torque could be expected to be insufficient. Thirdly, the extent to which donned bobbins will seat and settle to a desired level or height in relation to the spindles is important to proper package buildup and automatic doffing, among other things. Accordingly, a so-called bobbin line or prescribed level for the bottom ends of the bobbins in relation to the spindles was established, and deviations in excess of H16 inch above or below that level were taken to signify that the seatings of the bobbin on the spindle were not within a desirable tolerance.

Common spindletip tapers were matched with cooperating bobbin-seat tapers to account satisfactorily for all three of the factors just described. For desired operation with a spindle-tip taper of 0.025 inch/inch, which is that discussed in connection with tip 8 and which is in perhaps the most wide-spread usage, the bobbin-seat taper was determined as about 0.032 inch/inch, and

representing an increase of 0.007 inch/inch, plus or minus a practical tolerance of 0.002 inch/inch, or an increase in bobbin taper of about 28 percent. The said tolerance of plus or minus 0.002 inch/inch is about what one can realistically expect to achieve in forming the internal bobbin seat surfaces by reaming or pressing. With a spindle-tip taper of 0.080 inch/inch, the bobbin-seat taper was established at about 0.105 inch/inch, representing an increase of 0.025 inch/inch, or 31 percent. With a spindle tip taper of 0.100 inch/inch, it was found the bobbin-seat taper should be about 0.132 inch/inch, representing an increase of 0.032 inch/inch, or 32 percent. With a spindle-tip taper of 0.150 inch/inch, the bobbin-seat taper should be about 0.204 inch/inch, representing an increase of 0.054 inch/inch, or 36 percent. And, with a spindle-tip taper of 0.200 inch/inch, the bobbin-seat taper should be about 0.272 inch/inch, representing an increase of 0.072 inch/inch, or 36 percent. In FIG. 3, these critical increases in bobbin-seat taper, in inch/inch, appear along the axis of the ordinate, and the spindle-tip tapers appear along the axis of the abscissa; the resulting plotted curve 17 does not deviate significantly from linearity, and the prescribed increase in taper in accordance with these teachings can be said to be about one-third.

The tapered internal seating surface of the bobbin is preferably formed within a bushing-type seat insert 13, preferably made of substantially the same material as that of the bobbin tube 10, although in other instances the bobbin interior surfaces may be reamed or otherwise formed directly into the the desired shapes with the desired dimensions and tapering. Similarly, the insert may be ofa material, such as plastic, different from that of the bobbin tube. Below the level 18 at which the spindle tip engages the tapered interior bobbin seat, the axial length 19 of the tapered bobbin seat surfaces is intentionally kept very short, preferably of the order of A inch (9/32 inch being selected for the bobbin seat illustrated in FIG. 2), and less than the diameter of the spindle tip at level 18 but not less than about A; inch. This short effective length over which the relatively close tapered surfaces of the spindle and bobbin can abrade while being mated avoids undue frictional drag which could otherwise prevent the bobbin from seating itself rapidly and solidly as it is donned. Further, as wear occurs, the spindle tip and bobbin seat cannot then develop a broad-area excessively tight fit.

Rounded crown 9 of the spindle tip should not be allowed to bear against any bobbin surfaces once the bobbin has been seated on the spindle tip, else the resultant forces can cause the bobbin to lift, to lose drive torque, and even to jump up from the spindle at high speeds of 10,000 to 15,000 rpm. Such tendencies are particularly prevalent when the lower end of the bobbin is dimensioned to make a close fit with the spindle, for the aforementioned vibration-suppression purposes, as by way of the illustrated bushing-type insert 20. In that connection, the described greater taper or slope of the internal bobbin seat surfaces is advantageous in that it is nevertheless less than the slope of line tangents to the surfaces of crown 9, and, although the bobbin seat surfaces extend upwardly beyond the crown, no undesired contacting can occur.

It is self-evident, of course, that the tapering spindle tip and cooperating tapering bobbin seat surfaces must be of diameters permitting the improved fit to be realized. Accordingly, for purposes of completeness, it is noted that the construction FIG. 2 involves a diameter 35 for the upper interior of bobbin seat 13 which is 0.450 inch, and that the diameter of the spindle tip 8 at the upper end where it merges with crown 9 is 0.475 0.480 inch, the spindle diameter below the tip being 0.678 0.680 inch. Overall, the axial length 21 of the bobbin seat insert is l3/l6 inch in the specific example under discussion.

The improved one-third greater tapering of bobbin seats and short seat length. as described above, serve to avoid major doffing difficulties. but. inasmuch as bobbins are sometimes dropped onto the spindles. or donned. with substantial force; the latter action can tend to jam the seats together with excessive locking or sticking effects. and thereby make mechanical doffing difficult nevertheless. As has been said. the problems can be severe when spindle-tip taper exceeds 0.066 inch/ineh. in this connection. the bobbin is constructed to develop automatic drag or breaking actions with the spindle as it is donned. For those purposes, the bobbin H is provided with a further tubular bushing or insert 22., just below the seat insert 13, which has an internal diameter only slightly greater than the external diame ter of the spindle below the tip (example: about 0.012 0.014 inch greater) but of lesser internal diameter, nevertheless, than that of the lower end of the bobbin seat 13. This relationship assures the presence of an exposed shoulder" 23 at the lower inner edge of insert 13, against which the spindle tip crown will be somewhat stopped if the bobbin is being donned too rapidly and forcefully. Insert 22., which is preferably about an inch in axial length, serves to frictionally engage the spindle tip under similar circumstances. to prevent the bobbin from dropping too swiftly, as well as preventing undue vibration and looseness of the bobbin in relation to the spindle when full seating is not effected.

It should be understood that the embodiments and practices described and portrayed herein have been presented by way of disclosure, rather than limitation, and that various modifications, substitutions and combinations may be carried out by those skilled in the art without departure from the spirit and scope of this invention in its broader aspects and as set forth in the accompanying claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. A readily doffable high-speed bobbin structure for mounting in combination with an elongated rotatable upright spindle having a frusto-conical external seat tapering toward an upper end thereof, comprising an elongated tubular bobbin proportioned to be donned in mated relationship about the spindle, said bobbin having an internal seat near an upper end thereof which is frusto conical and tapered toward said upper end. the taper of said bobbin seat extending above and below a position at which the diameter of said internal seat substantially matches a diameter of the external spindle seat near the upper end of the spindle, said taper of said internal bobbin seat being substantially one-third greater than that of the external spindle seat, the surfaces of said bobbin seat above said position having slope sufficiently different from slopes of the spindle surfaces above said position to avoid contact with said spindle surfaces under all conditions of permissible displacements between said bobbin and spindle, and the axial length of said tapered bobbin seat below said position being relatively short and smaller than the diameter of said spindle seat at said position. whereby said bobbin may be donned and doffed readily and the bobbin may be driven efficiently at high speeds by the spindle without undue raising, lowering or vibration.

2. A readily-doffable high-speed bobbin for mounting in combination with an elongated rotatable upright spindle as set forth in claim 1 wherein the lower end of said internal bobbin seat projects inwardly from ad a cent inner surfaces of said bobbin therebelow and forms a shoulder which may engage the tip of said spindle during donning and thereby suppresses excessively forcefull seating of the bobbin on the spindle.

3. A readily doffable high-speed bobbin for mounting in combination with an elongated rotatable upright spindle as set forth in claim 2 further including internal surfaces of said bobbin immediately below said bobbin seat which are of lesser diameter than said shoulder and of only slightly greater diameter than juxtaposed exterior surfaces of the mated spindle, said further internal surface extending axially for a distance which promotes sufficient scraping of the spindle tip thereagainst during donning to decelerate the bobbin and prevent jamming of said seats.

4. A readily-doffable high-speed bobbin for mounting in combination with an elongated rotatable upright spindle as set forth in claim I wherein said taper ofsaid spindle seat is between about 0.025 and 0.200 inch per inch, and wherein the related taper of said bobbin seat is substantially linearly related thereto over the range between about 0.032 and 0.272 inch per inch.

5. A readily doffable high-speed bobbin for mounting in combination with an elongated rotatable upright spindle as set forth in claim 4 said bobbin is about twelve inches in length, wherein said tapered bobbin seat extends for an axial distance of about inch. and wherein the spindle seat at said position has a diameter of about /2 inch.

6. A readily-doffable high-speed bobbin for mounting in combination with an elongated rotatable upright spindle as set forth in claim 4? wherein said axial length of said tapered bobbin seat below said position is be tween about Vs inch and A inch.

7. A readily doffable high-speed bobbin for mounting in combination with an elongated rotatable upright spindle as set forth in claim 1 wherein said internal tapered bobbin seat comprises surfaces of a tubular insert affixed within said bobbin near said upper end thereof, and wherein said bobbin has a further tubular insert near the lower end thereof having an inner diameter just slightly greater than that of juxtaposed external surfaces of a spindle mated with said bobbin.

8. A readily doffable high speed bobbin for mounting in combination with an elongated rotatable upright spindle as set forth in claim 3 wherein said tapered bobbin seat and said further internal surfaces comprise inner surfaces of at least one tubular insert affixed within said bobbin near said upper end, and wherein said distance is about 1 inch.

Claims

1. A readily doffable high-speed bobbin structure for mounting in combination with an elongated rotatable upright spindle having a frusto-conical external seat tapering toward an upper end thereof, comprising an elongated tubular bobbin proportioned to be donned in mated relationship about the spindle, said bobbin having an internal seat near an upper end thereof which is frusto conical and tapered toward said upper end, the taper of said bobbin seat extending above and below a position at which the diameter of said internal seat substantially matches a diameter of the external spindle seat near the upper end of the spindle, said taper of said internal bobbin seat being substantially onethird greater than that of the external spindle seat, the surfaces of said bobbin seat above said position having slope sufficiently different from slopes of the spindle surfaces above said position to avoid contact with said spindle surfaces under all conditions of permissible displacements between said bobbin and spindle, and the axial length of said tapered bobbin seat below said position being relatively short and smaller than the diameter of said spindle seat at said position, whereby said bobbin may be donned and doffed readily and the bobbin may be driven efficiently at high speeds by the spindle without undue raising, lowering or vibration.

1. A readily doffable high-speed bobbin structure for mounting in combination with an elongated rotatable upright spindle having a frusto-conical external seat tapering toward an upper end thereof, comprising an elongated tubular bobbin proportioned to be donned in mated relationship about the spindle, said bobbin having an internal seat near an upper end thereof which is frusto conical and tapered toward said upper end, the taper of said bobbin seat extending above and below a position at which the diameter of said internal seat substantially matches a diameter of the external spindle seat near the upper end of the spindle, said taper of said internal bobbin seat being substantially one-third greater than that of the external spindle seat, the surfaces of said bobbin seat above said position having slope sufficiently different from slopes of the spindle surfaces above said position to avoid contact with said spindle surfaces under all conditions of permissible displacements between said bobbin and spindle, and the axial length of said tapered bobbin seat below said position being relatively short and smaller than the diameter of said spindle seat at said position, whereby said bobbin may be donned and doffed readily and the bobbin may be driven efficiently at high speeds by the spindle without undue raising, lowering or vibration.

2. A readily-doffable high-speed bobbin for mounting in combination with an elongated rotatable upright spindle as set forth in claim 1 wherein the lower end of said internal bobbin seat projects inwardly from adjacent inner surfaces of said bobbin therebelow and forms a shoulder which may engage the tip of said spindle during donning and thereby suppresses excessively forcefull seating of the bobbin on the spindle.

4. A readily-doffable high-speed bobbin for mounting in combination with an elongated rotatable upright spindle as set forth in claim 1 wherein said taper of said spindle seat is between about 0.025 and 0.200 inch per inch, and wherein the related taper of said bobbin seat is substantially linearly related thereto over the range between about 0.032 and 0.272 inch per inch.

5. A readily doffable high-speed bobbin for mounting in combination with an elongated rotatable upright spindle as set forth in claim 4 said bobbin is about twelve inches in length, wherein said tapered bobbin seat extends for an axial distance of about 3/8 inch, and wherein the spindle seat at said position hAs a diameter of about 1/2 inch.

6. A readily-doffable high-speed bobbin for mounting in combination with an elongated rotatable upright spindle as set forth in claim 4 wherein said axial length of said tapered bobbin seat below said position is between about 1/8 inch and 1/4 inch.