US2771910A

US2771910A - Shuttle spring

Info

Publication number: US2771910A
Application number: US406680A
Authority: US
Inventors: Willard W Taft
Original assignee: Draper Corp
Current assignee: Draper Corp
Priority date: 1954-01-28
Filing date: 1954-01-28
Publication date: 1956-11-27
Anticipated expiration: 1973-11-27

Description

Nov. 27, 1956 Filed Jan. 28, 1954 INVEN TOR. WILLARD W. TAFT ATTORNEY United States Patent "ice SHUTTLE SPRING Willard W. Taft, Hopedale, Mass., assignor to Draper Corporation, Hopedale, Mass., a corporation of Maine Application January 28, 1954, Serial No. 406,680

4 Claims. (Cl. 139-207) This invention relates to bobbin holding springs for shuttles.

It is a general object of the invention to devise a bobbin holding spring for shuttles the life of which shall be greatly increased and which shall also serve betterto hold the bobbin in proper alignment.

It is a more specific object of the invention to devise a spring of the type described which actually comprises inner and outer spring means one of which holds the bobbin directly and the other of which serves to reinforce the holding power of the first and to damp its vibrations.

It is a further object of the invention to provide a spring combination which shall serve to prevent the usual opening of the bobbin holding spring jaws after a short period of use.

Other objects of the invention will become apparent from the following disclosure.

Shuttles, especially those employed in automatic, bobbin-changing looms, are equipped with a spring fixed securely in a recess at one end of the shuttle and having spring jaws grooved internally at their ends to receive and hold a filling bobbin in a known manner. Desired characteristics of such a spring are that it shall be simple, light, easily made and that it shall hold the bobbin rigidly in desired alignment yet permit ready ejectionof that bobbin when empty of filling along with entry of the next full bobbin under the action of the replenishing means. It should also have a useful life at least equal to the longest life to be expected from the shuttle itself, but that is not always the case. In fact, many springs, although of fine steel and subjected to shot peening, do not last anywhere near as long as the shuttle. replacement is expensive, time-consuming, and breakage may result in other troubles which are obviously to be avoided if possible.

One other characteristicof the springs now utilized is that after a short period of use, the bobbin holding spring jaws thereof open or spread for perhaps to of an inch. This means that with an initial dimension which permits easy entrance and exit of a bobbin and proper holding, a loosening and misalignment is to be expected after a short period of operation. This is a fault which is more important than might appear at first thought since the grooves in which the bobbin rings seat are subject to fairly rapid wear anyway. Thus these two factors are additive and it may not be long before a spring will hold its bobbin so loosely as to permit a considerable amount of free movement of the bobbin tip along with the weaving problems attendant thereon.

According to the instant invention the life of a spring of the type described is greatly lengthened by cutting down its harmonic vibrations, especially those of higher frequency. A spring of more or less the usual design is employed in conjunction with a second damping or keeper spring which is of similar contour and also of about the same general dimensions in length and width although preferably of diiferent and lesser thickness. At least the supplementary or keeper spring should have aidiiferent vibrational frequency so.as. to interrupt .and

Their 2,771,910 Patented Nov. 27, 1956 damp the vibrations of the main spring. In actual practice it has been found that the use of a supplementary spring fitted around and having frictional, pressure engagement with the main or holder spring results in much less spring failure and thus longer life. 'In tests springs thus devised have stood up under repeated transfer cycles far beyond any life expectancy heretofore possible with the conventional single spring.

Along with this increase in life of the spring it has been found that, with use, the combined holder spring and supplementary or keeper spring, instead of opening at the jaws after a period of use, actually close slightly. The complete reason for this is not known at present, although, apparently, the frictional, pressure engagement actually effects a sort of cold working the metal, and, of course, the fatigue characteristics are markedly different.

In carrying the invention into practice the supplementary damping spring is formed with its free ends or jaws spaced a distance considerably less than the spacing of the bobbin holding spring. The former is then snapped over the latter and, when the assembly is clamped in position in a shuttle, the spring jaws of the outer member press inwardly against those of the inner and there is an area of contact established between the two the ex- 7 tent of which depends upon the contours of the parts.

In some instances it may be desirable to provide more surface contact or frictional damping in conjunction with periodic interruption of the vibrations and vice versa.

The invention will be described in greater detail by reference to certain preferred embodiments thereof as illustrated in the accompanying figures ofdrawing where- Fig. 1 is a plan view of a shuttle and bobbin with the invention applied.

Fig. 2 is a detail view of an inner and outer spring showing respective contours of each prior to assembly.

Fig. 3 is a view showing the outer spring snapped over the inner, but not clamped in final form as it will be when both are assembled in a shuttle.

Fig. 4 shows such final form and an outer spring of such contour that contact is made adjacent the jaw ends only.

Fig. 5 is a side view of the assembled springs.

Fig. 6 is a similar view showing a modification in which contact is much more extended.

Fig. 7 shows still another modification in which contact is substantially complete.

Now referring to Fig. 1, a loom shuttle 10 is shown having the usual bobbin cavity at one end of which the shuttle is further recessed for the reception of a shuttle spring generally indicated by numeral 11 and a spring cover 12. The latter may be of conventional construction.

Spring 11 is held in place in the shuttle material, wood, plastic, etc., bythe usual cross bolt (not shown) and by the cover 12 held down by a screw or bolt 13. A block 14 of wood, steel or other material may be used to fillthe space between the relatively rigid, U- shaped clamping portions 15 of the spring and the upper and lower cover plates and to resist the clamping forces as the bolts or screws are tightened.

A bobbin 16 having a filling wound package (not shown) is held in position by the spring means, the rings 17 at the bobbin butt being engaged within grooves at the inner parts of the spring jaws as is the usual practice with automatic loom shuttles. v

The spring 11 is actually comprised as a multiple part member having an inner spring the jaws 18 of which are grooved and'the rigid, U-shaped portion 19 of which serves as the major clamping or retaining means. This spring is of about the same general shape and thickness as conventional springs, although it may be made slightly thinner. It" is so fofmed that its jaws converge to a spacing slightly less than theldiameter of the bobbin rings, e. g., for rings of 1%; inches outside. diameter ,the. jaws should permit passage of a gauge 75 of ,an inch wide. Now in the case :of springs as heretofore employed, a shuttle after. a few. days use would, .if its spring were gauged again, show an opening of the jaws of perhaps 1K]; of an .inch. As these springs may well open to 4 of aninch later, alongwith. wear .of the ring :grooves, it has been the exerience of many mills that their weaving problemshave been increased since the bobbins are held loosely, and. in improper alignment.

It hasbeen found that the difficulty above noted and also. the spring failure due. toufatigue of the metal are both cut toan amount far lessthan heretofore believed possible by supplementing the innerspring with ,an outer spring member 20 which maybe called a keeper spring ordamping spring. This outer spring is preferably of about the same general shape and extent as the inner, but of thinner stock. Its vibrational frequency should be materially different from that of the .inner and, as shown in Fig. 2,'.it hasits free ends converged to a much greater extent than the ends of spring jaws 18. This Fig. 2 shows the parts not in assembled relationship, but with .the damping spring 20 (full lines) superimposed upon the inner spring (dot-and-dash'lines).

.In Fig. 3, the outer spring has been snapped over the inner andtakes ashape such that there is contact at the .bend of the U-portions and at the tips of the jaws. However, when this spring assembly is clamped in the recess provided for it in a shuttle and in which it fits rather closely, the shape taken by the parts is that of Fig'. 6. The outer spring then conforms more closely to the contour of the inner so that there is substantially complete contact of the U-shaped clamping portions and considerable contact along the jaws and bent parts. The amount of contact at these latter areas. may be varied depending upon whether more or less frictional damping is desired. 7

In Fig. 6 contact along the entire straight part of the jaws is provided, while in Fig. 4 there is contact adjacent the ends only, that is, about as far from the ends as the grooves extend, e. g., /2 to A of an inch.-

In Fig. 7 contact is provided insofar as is practicable over the entire extent of the intermediate surfaces. Of course, these extents or limits may vary as required and in order:to.get best results, dimensions and contact may be varied with material, speed and forces applied at transfer of .the bobbins, weight of-bobbins, original spring jaw separation, and other factors.

In Fig. a side view of the spring assembly shows a preferred form of parts which-may be advantageously utilized,

Tempered spring steel-of fine quality is to be used and preferably the parts should be shot peened as the fatigue resistance is thereby greatly improved. In use, spring breakage due. to fatigueof metal, is reduced to a negligible, percentage, and. along with that, the effect of the outer keeper or damping spring member is one which prevents opening or spreading of the jaws with use; in fact, tests show theopposite takes place.

4 cept may be carried out in a number of ways This invention is, therefore, not to be limited to the precise details described, but is intended to embrace all variations and modifications thereof falling within the spirit of the invention and the scope of the claims.

I claim:

1. For a loom shuttle, filling bobbin holding means which comprises spring gripping jaws adapted to be retainedinone end of a :shuttle, said jaws'comprisingan inner jaw-.mernber-having a rigid clamping portion and extending therefrom opposed, flexing jaw members having curved portions terminating in relatively straight end portions with meansuadjacentzsaidrend portions for holding a bobbin, an outer member comprising a leaf spring of substantially the same general contour as the inner spring, of substantially the. same .extentandhaving pressure and frictional engagement with the relatively straight end portions only. of said spring jaws.

2.'For a loom shuttle, a filling bobbin holding, means which comprises spring .gripping jaws adapted to be retained in one end of a shuttle, said jaws-comprising a rigid clamping portion and extending therefrom, opposed flexing jawv members with means defining grooves adjacent their ends for holding a bobbin, and means for reinforcing the holding power of said spring gripping jaws and .for damping the vibrations thereof which comprises a leaf spring means of substantially the same length assaid spring. gripping jaws and having substantial pressure and frictionalengagement withthe end portions only of said spring jaws.

3. For a loom shuttle, a filling bobbin holding means which comprises spring gripping jaws adapted to be retained in one end of a shuttle, .said jaws comprising a rigid clamping portion and extending therefrom, opposed flexing jaw.members having curved portions terminating in:.relatively-straight end portions with means defining grooves adjacent said end portions for holding a bobbin, andmeans for reinforcing the holding power of said spring gripping, jaws and for damping the vibrations thereof which comprises other leaf spring means having a vi.- brational frequency different from that of said spring gripping jaws, said means having its free ends terminating at substantially the ends of said spring gripping jaws and having substantial pressure and frictional engagement with:the relatively straight end portions only of said spring jaws.

I 4. For a loom shuttle, a filling bobbin holding means which comprises spring gripping jaws adapted to be retainedin one end of a shauttle, said jaws comprising While it ispreferred that the inner spring be of thicker stock than the outer, these as well as other dimensions may be varied within rather wide limits. The thickness of the springs may be increased'as required to hold lighter or heavier packages. Heretofore very heavy packages have been hard to use because, with the dimensions permissible, a single spring of suitable strength a rigid clamping portion and extending therefrom, opposed fiexing jaw members having curved portions terminating in relatively straight end-portions with means defining grooves adjacent said endportions for holding-a bobbin, and means for reinforcing the holding power of said spring gripping jaws and for damping the vibrations thereof whichcomprises other leaf spring means having a vibrational frequency different from that of said. spring gripping jaws, said means before assembly havinga greater contraction of its free ends than the contraction of the said jaw ends, thereby to develop initial pressure against the jaw ends when assembled, said leaf spring means being substantially coextensive with the gripping jaws and having pressure and frictional engagement with the relatively straight end portions. only of said spring jaws.

References Cited in the file of this patent UNITED STATES PATENTS 1,017,782 McCaslin Feb. 20, 1912 2,138,221 Turner Nov. 29, 1938 2,270,821 Kaufmann Jan. 20, 1942 V FOREIGN PATENTS 313,153 Italy Dec. 16;, 1933 336,894 Italy Feb. 24, 1936 461,371 France Och-27,1913