US2891798A - Winding mandrel for packaging glass strands - Google Patents

Description

June 23, 1959 x R. E. SMITH 2,891,798

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WINDING MANDRELFOR PACKAGING GLASS STRANDS I Filed Nov. 13, 1956 2 Sheets-Sheet z INVENTOR;

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United States Patent WINDING MANDREL FOR PACKAGIN GLASS STRANDS Roy E. Smith, Anderson, S.C., assignor to Owens-Coming Fiberglas Corporation, a corporation of Delaware Application November 13, 1956, Serial No. 621,785

5 Claims. (Cl. 279-2) The present invention relates generally to mechanism for drawing and winding a glass thread or strand of the type formed by gathering together a large number of attenuated glass filaments. More specifically the invention pertains to a mandrel for holding an expansible, resilient tube upon which a glass strand is wound into a package.

Because of the inherent greater strength of a glass strand and the speed with which it has been customarily wound upon spools or tubes, a greater compression force is developed in the winding operation than accompanies that of other fibers of natural and synthetic origin.

This high compression force has the objectionable elfect of constricting the commonly used plastic forming tube, preferred because of its light weight and wearing qualities, into a smaller diameter, which makes it difficult to remove the tube from the mandrel. It also is inclined to bind the turns of the glass strand so tightly together around the tube that the unwinding operation for subsequent use or treatment, such as twisting and plying, is jerky and uneven.

During the first production of glass strands these difiiculties were encountered and in efforts to overcome them special mandrels for holding the winding tubes were developed. A typical design and one successfully used in modified form for many years is shown in US. Patent No. 2,274,681 granted to Fletcher on March 3, 1942. In this device and variations thereof, there are long narrow fingers, loosely carried by the mandrel, which are thrust outwardly against the interior surface of the forming tube by the centrifugal force developed by the rotation of the mandrel in the winding process. This centrifugal force neutralized the constricting effect of the strand winding upon the tube, leaving the tube loose enough upon the mandrel to be easily removed. Also the centrifugal force slightly expanded the tube during rotation of the mandrel; and the return of the tube to its original size at the termination of the rotation sufficiently reduced the binding between turns of the thread that subsequent unwinding of the thread or strand from the tube was smoothly accomplished.

While mandrels of a design typified by the showing of the Fletcher patent served quite efficiently for many years, recently, under the more demanding requirements arising in an expanding industry, their performance has proved inadequate.

Constantly growing uses and sales have called for ever increasing production. This demand was satisfied through the adoption of improved glass compositions, and glass melting and feeding equipment, developed by vigorous research, which made it feasible to draw and wind glass filaments into strands at considerably greater speeds. Winding tubes are now frequently rotated at or in excess of ten thousand revolutions per minute. The compression force upon the tube developed by the winding operation has increased accordingly and to a degree that the Fletcher type mandrels have difficulty in withstanding. Failure has been encountered most frequently when an elongated mandrel and tube were utilized for receiving two separate strands to form two packages of wound strands on the single tube.

Investigation by applicant has led him to conclude that the fingers of the established mandrel design possessed insutficient mass to create the correct centrifugal force to properly counteract the constricting force of the winding operation, and that the comparatively thin finger retaining structure of the mandrel likely deformed or bulged outwardly under higher speeds and in their elongated form required for double packages. Then, too, the fingers were spaced quite a distance apart and their separated lines of thrust could effect an out-of-round expansion of the tube.

Additionally, applicant observed that the number and arrangement of parts of the previously used mandrel made the mandrel rather expensive to build and the parts diflicult to align and assemble. It was also noted that the outer section of the wound strand in the final package was more inclined to be under too great a tension for easy unwinding.

The principal object of this invention is broadly to provide a winding mandrel that will function efiiciently in supporting an expansible, resilient tube upon which either one or two glass strands are very rapidly wound and to produce packages of glass strands so formed that are fully satisfactory in subsequent use.

More specifically, a prime object of this invention is to provide centrifugally propelled elements adapted to embrace the major portion of the inner surface of a winding tube mounted on the mandrel.

Another object is the provision of a mandrel which expands the resilient winding tube in a manner that results in no serious binding between the courses of the glass strand wound in a package around the tube.

A further object is to provide a mandrel having a minimum number of parts which can be economically produced and easily assembled.

Other objects and advantages are also secured through the novel features of the invention of which the following are considered of special pertinence.

Instead of spaced narrow fingers for engaging the inner circumference of the winding tube, the mandrel of this invention has segments of T cross section with outer surfaces contacting the major portion of the interior of a tube mounted on it.

A single piece, solid core constitutes the main body member of a mandrel embodying the invention. The core has an axial bore for receiving a driving spindle and outer grooves acting as retaining sockets for the segments.

The core and the segments have cross sections of uniform dimensions throughout their lengths.

The weight of the segments is proportioned in respect to the developed winding compression to permit gradual contraction of the expanded tube during the last portion of the package formation.

Attention will be directed to other features of the invention in the following description and by reference to I the drawings.

In the drawings,

Figure l is a diagrammatic illustration of a conventional process for glass strand forming and winding into packages;

Figure 2 is a longitudinal section, taken on line 2--2 of Figure 3, of a mandrel and tube embodying the invention;

Figure 3 is a partial end view and cross section of the mandrel of Figure 2, the section being taken on the line 3-3 of Figure 2;

Figure 4 is a perspective view of one of the segments; and

Figure is an enlarged broken section comparable to the section of Figure 3 showing the segments depressed during the last part of the winding operation.

Referring to the drawings in more detail, in Figure l is depicted, diagrammatically, a glass melting furnace 6 and a multiple-nozzle bushing 7 from which streams of glass 8 are discharged and attenuated into continuous filaments. The individual filaments, which usually number from one to two hundred, are gathered together into a single thread or strand 9 by a device such as hook 10.

A sizing coat is generally applied to the filaments adjacent the gathering device by some means such as a spray nozzle or by being passed over a pad saturated with a sizing liquid. The strand 9 is then drawn down and wound into a package 13 upon the spool or tube 12. A traversing device as indicated at M guides the strand back and forth over tube 12. The traversing mecha nism 14 is a figurative showing of that disclosed in the patent to Fletcher No. 2,377,771 dated June 5, 1945. This mechanism may, of course, be of any conventional design capable of functioning at the high speed required.

A bracket 15 supporting spindle 16 on which the tube mandrel 18 is mounted extends upwardly from the housing (not shown) containing the motor and driving mecha nism for rotating the spindle through belt 19 running over pulley 29. More details of spindle it: and mandrel 18 may be observed in the subsequent figures of the drawing, with attention first directed to Figure 2. As seen in this view a bearing assembly 21, one of a pair Within the bracket 15, supports the spindle close to the position of the mandrel on the spindle. The core 24, constituting the main body of the mandrel 18, is held on the spindle against the tapered enlargement 26 of the spindle by a lock nut 27.

In the disclosed embodiment, the core 24 has twelve grooves 39 running longitudinally in the outer face of the core for the full length thereof. The grooves are similarly dimensioned and symmetrically positioned. They are dovetail in cross section, being wider at their bases.

Above the flat bottom of each groove is a shallow section with straight sides. From this section the sides converge upwardly. The converging part 31 of the groove terminates in a narrow straight-sided top portion 32.

Locked within each groove and extending the full length thereof is a tube contacting segment 34. The segment has a T cross section with a flaring base 35 conforming in contour with the converging part 31 of the groove. The portion of the segment, forming the top of the T section, is disposed exteriorly of the core and has an outer surface curved to fit the inner circumference of the winding tube positioned on the mandrel. The segment has a short straight-sided neck 37 joining the top of the segment with the flaring base 35.

The ribs 38, lying between the grooves, are slightly peaked. Each flat half of the peak shape is below the flat underside of one side of the T portion of the adjacent segment.

The segments 34 are inserted into the grooves from the exposed end of the core before the head piece is fastened by bolts 41 upon the outer end of the core. The segments are then retained within the grooves between head piece dt? and the collar 43 bolted against the other end of the core.

In each groove beneath the base 35 of the segment is a generally fiat spring 46 extending in a slight are between the ends of the groove. These springs incline the segments to their outermost positions when there is no tube over the mandrel, as illustrated in Figure 3.

In the use of the mandrel of this invention, the wind ing tube 12 is first placed over the mandrel. depress the segments 34 against the light tension of the springs 46. The outer ends of the segments are tapered to facilitate depression of the segments by the tube. The

springs have sufficient strength to retain the tube in place without impeding its easy removal. While the tubes are generally conventional in shape and in their plastic composition, for purposes of this invention it is very desirable that their resilience and dimensions be uniform.

Before the winding drive is actuated to turn the mandrel with the tube mounted on it, the starting end of the glass strand is manually tied around the tube. With the glass strand thus secured to the tube the Winding drive is set in operation. This may be accomplished through release of a clutch which has been held in drive-disengaging position by the foot of the operator while he placed the tube on the mandrel and fastened the leading end of the glass strand around the tube. As the tube acceleretes to its selected speed (which may be ten thousand or more revolutions per minute) the segments are pro polled by centrifugal force from their retracted positions upon the springs outwardly against the interior of the tube.

The outward movement of the segments is radially guided by sliding contact between the straight sides of the narrow part 32 of the grooves and the necks 37 of the segments. With the uniform cross section throughout their lengths the segments apply pressure evenly against the inner wall of the tube.

The initial outward thrust of the segments moves them as far as their loose retention within the grooves permits. This brings the flaring base 35 of each segment against the complementarily converging portion 31 of the groove, as illustrated in Figure 3. Upon the tube now expanded to its maximum diameter, the glass thread is Wound with the turns distributed back and forth across the tube by the action of the traversing mechanism 14.

With the strength of the current glass compositions and at the new high speeds of rotation, considerable constricting force upon the tube is developed by the winding operation. The mass of the segments, however, is such that enough counter pressure is exerted to hold the tube in its fully enlarged form until a substantial portion of the package of giass strand is wound upon the tube.

As the diameter of the wound package becomes larger the centripetal winding pressure increases. This is due, not only to the faster drawing of the strand required to supply the longer length to circumscribe the growing package during each revolution, but also to the slight stretching of the glass strand as it is wound. While the elastic property is limited to a maximum elongation of three percent, it is sufficient to produce a build up of the inwardly directed pressure as the layers of the strand accumulate.

Of those elements contributing to the development of the opposed forces, those subject to control are preselected in order to permit the increasing centripetal winding pressure to slowly overcome the centrifugal pressure of the segments during the finishing portion of the package forming operation. The mass of the segments is one of the most governable elements and its modification is the principal means of attaining the desired relationship between the opposed forces.

The sturdy, solid construction of the core resists any deformation due to centrifugal force and therefore does not adversely influence the shape of the tube. The segments also are built with sufiicient cross section that they remain fully rigid, and cooperate in applying an expanding pressure uniformly against substantially the full inner surface of the forming tube. The non-deflecting character of the core and segments enable them to be utilized in elongated form to receive and properly wind two strands into separate packages upon a tube of a length suitable for double packaging.

The core and the segments constituting the main parts of the mandrel, and there being no intermediate elements, the mandrel is more easily produced and assembled. No alignment problem is involved.

The tapered contact area between the segments and the converging sides of the grooves, when the segments are in their most expanded positions, is most effective in firmly retaining the segments in place. This design makes both the core and the segments stronger than they would be with more severe undercutting to provide fiat contact between these elements.

The tapered surfaces of the grooves not only oppose the outward thrust of the segments but are also adapted to receive lateral pressure from the segments when they tend to move tangentially during the periods of acceleration and deceleration. This reduces the wear from such side thrust to which the straight radially guiding sides of the groove and the necks of the segments would otherwise be subjected.

It should be observed that the core and the segments together constitute a substantially solid, symmetrical, cylindrical mass with the exterior portions of the segments completing the cylinder in which the polyhedral core is inscribed. There is, accordingly, no area in the assembly where weight is concentrated which in rotation might cause a whipping or twisting effect.

While the disclosed embodiment of the invention is a preferred form various modifications may be resorted to within the scope of the invention and without too detrimental effects.

For instance, square instead of angled shoulders may be utilized for retaining the segments Without seriously jeopardizing the advantages gained through other features of the invention. Also, a mandrel having wider spacing between tube contacting faces of adjoining segments would serve satisfactorily in many cases. The particular number and shape of the segments selected for disclosure herein may, of course, be moderately altered without loss in their overall efiectiveness.

I claim:

1. A rotatable mandrel for holding an expansible, resilient tube upon which a glass strand or the like is wound to form a package, which comprises as integral, cylindrical body member with an axial bore for receiving a driving spindle, and segmental elements of T cross section carried by the body member and extending the full length thereof, said elements being movable by centrifugal force, upon rotation of the mandrel, radially and outwardly from the body member, both said body member and said segmental elements being solidly formed with a substantially uniform cross section throughout their lengths, whereby under rotation of the mandrel they are not deformed by centrifugal force and the elements are moved outwardly with equal longitudinally distributed force.

2. A rotatable mandrel for holding an expansible, resilient tube upon which a package of glass strand is wound, including an elongated, generally cylindrical body, substantially solid and uniform in cross section; gripping members, outwardly movable by centrifugal force, carried by the body and extending the full length thereof, said members being of uniform T shape in cross section; guiding means on the body comprising longitudinal grooves therein directing the members in radial paths, and limiting means comprising shoulders of lateral recesses in the grooves, restricting the outward centrifugal movement of the members.

3. A rotatable mandrel for holding an expansible, resilient tube upon which a glass strand is wound to form a package, which comprises an integral body member of generally cylindrical form having an axial bore for reception of a driving spindle and with exterior longitudinal grooves extending the full length of the body member; elongated segmental elements carried by the body member and movable by centrifugal force radially and outwardly therefrom, inner leg portions of the segmental elements projecting into the grooves and radially guided thereby, exterior portions of the segmental elements being laterally broadened; and elongated springs lyin-g lengthwise in the grooves and arranged to impel the segmental elements outwardly; said body member, segmental elements and springs being of approximately equal length, whereby they all contribute to the uniform distribution of the weight of'the mandrel.

4. A rotatable mandrel for holding an expansible, resilient tube upon which a glass strand is wound into a package, which comprises an integral body member having an axial bore for reception of a driving spindle and exterior grooves of dovetail cross section extending longitudinally of the body member, and segmental elements carried by the body member and movable by centrifugal force radially and outwardly therefrom, inner portions of the segmental elements projecting into the grooves and having lateral enlargements disposed beneath the angled shoulders of the dovetail configuration of the grooves, whereby outward movement of each segmental element caused by centrifugal force developed by rotation of the mandrel, is limited by the abutment of the lateral enlargements of the element against the angled shoulders of the associated groove.

5. A rotatable mandrel for holding an expansible, resilient tube upon which a package of a glass strand is wound, which comprises a body member having exterior grooves running longitudinally thereof, said grooves being roughly dovetail in cross section, broadened at their bases with sides converging from the bases to upper narrow sections of the grooves, said narrow sections being bounded by straight parallel extensions of the sides; segmental elements of T section carried by the body member and movable upon rotation of the mandrel by centrifugal force radially and outwardly therefrom, and legs on the segmental elements, constituting the upright portion of the T section, extending into the grooves, said legs having a lower flaring section and an upper generally straight portion, the grooves and the legs being so arranged that the narrow sections of the grooves guide the segmental elements in their radial movement by contact with the upper, generally straight portions of the legs, and the converging sides of the grooves limit the outward movement of the segmental elements by intercepting the lower flaring sections of the legs.

References Cited in the file of this patent UNITED STATES PATENTS 16,748 Reynolds Mar. 3, 1857 1,870,649 Rawson Aug. 9, 1932 2,128,980 Anderton Sept. 6, 1938 2,274,681 Fletcher Mar. 3, 1942 2,690,914 Bryant Oct. 5, 1954 2,738,980 Spahn Mar. 20, 1956

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