US2769439A - Bow string - Google Patents

Description

C. L. LAYER Nov. 6, 1955 Bow STRING Filed April 28, 1954 NVENTOR 7am/ice BY ya.

ATTORN EY United States Patent O 2,769,439 Bow STRING Y Clarence Layer, Downers Grove, Ill. Application April 28, 1954, Serial No. 426,090

4 Claims. (Cl. 1724-30) The present invention relates to improvements in bow strings, being particularly concerned with endless strand bow strings and the reinforcement of the strand against abrasion and unequal stresses.

It has been the practice in the past to reinforce the end loops and service portions of the bow string by spirally winding a reinforcing strand upon the bundle of strand sections making up the bow string. This practice has certain disadvantages among them being the tendency for the reinforcing strand to be displaced to expose the endless strand of the bow string. Also, where reinforcement is provided by a spirally wound strand, the individual strand sections of the endless strand may not be able to adjust themselves to equally distribute the stresses upon the bow string to each individual strand section, with the result that certain strand sections may be over stressed and ruptured and progressive breakdown of the bow string will result.

It is the object of the invention to provide an improved endless strand type of bow string in which the reinforcement of the endless strand is provided by exible material forming a tube within which the endless strand is protected from abrasion and has freedom of adjustment to equalize the stresses upon the individual strand sections. In one form, this tube is provided by wrapping a relatively wide band of thin sheet material upon itself. Another form of the invention contemplates a tube of a single ply of material either pre-formed or formed on the bow string at the time of assembly. A third form proposes to form the tube by coating or dipping the bow stn'ng in a suitable plastic followed by curing.

In the drawings,

Fig. l is an enlarged side elevational view, shown broken, of a bow string embodying the present invention,

Fig. 2 is a View similar to Fig. 1 of the entire bow string upon a smaller scale,

Fig. 3 is a diagrammatic elevational View showing the the method of manufacture,

Fig. 4 is a side view similar to Fig. 3 of a later stage of manufacture,

Fig. 5 is a fragmentary perspective view showing the manner in which the end of the sheet material is applied,

Fig. 6 is a cross-sectional view taken on section line VI--VI of Fig. 3,

Fig. 7 is a view similar to Fig. 6 taken on section line VII-VII of Fig. 4, and

Figs. 8 and 9 are views similar to Fig. 6 of modified forms of the invention.

Referring to Figs. l and 2, the finished bow string 10 is shown having tubular encased end loops 12 formed from unbundled portions of the endless strand, tubular reinforcements overlapping portions of the end loops 12 and encasing portions of the bundled endless strand adjacent the end loops 12 and a tubular encased service portion 16 which reacts against the end of the arrow.

'I'he method of making my improved bow string comprises the steps of coiling a single strand of suitable material back and forth between the hooks 18 a plurality of ,y 2,769,439 Patented Nov. 6, 1956 ICC times and then connecting the ends of the strand as indicated by the knot 20' to provide an endless strand having individual strand sections 20 collectively forming multistrand unbundled portions 22 and 24.

In Fig. 3, a relatively wide sheet 26 of extremely thin material is shown in the process of being coiled upon itself over the strand portion 22 to form a tube of reinforcement. The completed tube 28 is shown in Fig. 6 with the inner end of the sheet 26 being at 30 and the outer end at 32. In practice, the end 30 is preferably started between the individual strand sections andithen coiled upon the strand group of the portion 22 with the end 32 being heat sealed, or otherwise secured, in position to the outermost ply of the tube 28 upon which it is disposed.

Upon completion of the tube fabricated as shown in Fig. 3, the partially formed bowv string is shifted upon the hooks 18 to dispose the tubes 28 at the ends of the bow string to form the reinforced end loops 12, as shown in Fig. 4. At the right end of Fig. 4, the looped tube 28 is shown before the tubular reinforcement 14 on the left end has been applied.

In Fig. 7 the tubular reinforcement 14 is shown in section with the juxtaposed ends 'of the tube 28 being shown wrapped together with a sheet of material preferably corresponding to the sheet 26, one end of the sheet being at 36 and the other and outer end being at 38 and heat sealed, or otherwise attached to the outer ply of the resulting tubular reinforcement in the manner of the end 32.

To complete the fabrication of the bow string 10, all the strand elements 20 are bundled and wrapped together as a single group of strands to form the servicing portion 16 by coiling the thin sheet, preferably corresponding to the sheet 26, to form a reinforcing tubular construction upon that portion of the bow string with which the arrows engage. In cross-section the portion 16 will appear as shown in Fig. 6 with the exception that twice the number of strand elements 20 will be disposed within the coiled sheet material.

In practice, the same sheet material is preferably used to provide the tubular reinforcements 14, 16 and 28. The strand elements 20 are free to adjust themselves withing these tubular reinforcements so that the stresses placed upon the bow string 10 are equally distributed between the strand elements 20. Each tubular reinforcement is formed by wrapping a sheet of material, from 3" to 6 in width and in the order of .003 thick, around the gathered strand elements 20 from eight to ten times. The sheet material should be pliable and resistant to abrasion. It may be of numerous compositions. Polyethylene is suitable and has the desired property of head sealing. Polyvinyl chloride is another of the thermoplastics of the vinyl resins group of which many may be employed to form the sheet material 26.

As shown in Fig. 8, in lieu of a tubular reinforcement made up from many plies of material, a single ply encasement 40 is shown as a sleeve longitudinally split at 42 and heat sealed, or otherwise cemented, to form a solid tube having a substantially greater thickness than the sheet 26 but which may be of similar composition and function. In Fig. 9, the reinforcing tubular structure 44 is applied to the strand elements 20 as a plastic coating and then cured into an encasing sleeve corresponding to the structure 14, 16 and 28 of the form of the invention of Figs. l and 7, inclusive. 'lhe plastic employed would be selected and so applied as to avoid binding with the strand elements 20 as this would restrict their individual action and their ability to equalize the stresses.

Having thus described my invention what I claim is new and Idesire to protect by Letters Patent is:v

l. An archery bow string having a mnltistrand endless string body with a portion of the body subjected to abra- Sion in ruse'xand having a ,reinforcing tubular: structure" reirissasing thesame witlioutmtenference will; ille relative longitudinal movement of theV strands to equally distribute stresses to which the bow ystring is subjected in use.

.2.- .Amarehepybow .string as siened Ainclarn il :wherein -terial of substantial vWidth wrapped upon :itself to 'form a multiply tube.

string to form loops, elongated tubular reinforcements encasing `Said 199m .as ,vi/ell as the nndnidedsstlle indy asijacent said loops Vand lin theA area of the servicing portion of said bow string, the string portions making up said body having individuallongitudinal movement Within said reinforcement to equalize the stresses.

References Citeduthejle of this patent UNITEDv ,51A-BBS ,BATENTS 396,130 Willoughby `J an. 15, 1889 v 2,271,173 'Lay L Ilan'. 27,1942 2,398,876 ,Bailey .Apr.;23, 1946 2,401,291 S Is!1 i i1l1 m May 28, 1946 2,508,521 Lay May 23, 1950 ik lY i

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