US2423765A

US2423765A - Archery bow

Info

Publication number: US2423765A
Application number: US582026A
Authority: US
Inventors: William M Folberth; Parmelee Paul
Original assignee: FOLBERTH
Current assignee: FOLBERTH
Priority date: 1945-03-10
Filing date: 1945-03-10
Publication date: 1947-07-08
Anticipated expiration: 1964-07-08

Description

INVENToRs W/L/AM /V- FOLBEETH Affare/viva a? PAUL PAPMELEE W. M. FOLBERTH ET AL ARCHERY BOW Filed March 10, 1945 July 8, 1947.

Patented July 8, 1947 UNITED STATES. PATENT OFFICE ARCHERY BOW William M. Folberth, Cleveland, and Paul Parmelee, Cuyahoga Falls, Ohio; said Parmelee assignor to said Folberth Application March 10, -1945, Serial No. 582,02

14 Claims.

This invention relates to archery bows and more particularly to bows of laminated or built up construction.

A general object of the invention is to provide an improved bow of laminated construction which will be eicient and powerful and able to resist the severe strains encountered in service without breaking. Another object is to provide a bow having these desirable characteristics and which will be relatively easy and economical to manufacture.

As is well understood by those skilled in the art, tlie back of a bow, i. e., thatJ portion away from the user, is subject to tension, while the front or belly of the bow, i. e., the string side, which is toward the user, is subject to compression when the bow is bent. Because of this fact, for centuries, high gradel bows have been made of yew, for the heart wood of yew is strong in compression, while th'e sap wood is resilient and strong in tension. The wood of the yew thus combines in a single piece the two different, characteristics required in bows, and it has been the practice to make bows of yew with the sap wood toward the back and the heart wood toward the front. This has been an expensive and laborious process, :for it is necessary to carve the wood very carefully properly to follow the grain and to obtain the correct thicknesses of heart wood and sap wood throughout the bow.

Because of the scarcity of yew and the expense of manufacturing yew bows, modern bows have been made of laminations of different woods glued together in order to obtain the same sort of characteristics found in a single piece of yew. The laminations ordinarily are relatively thin, and in order to increase the strength and rigidity of the central portion of the bow andto provide a grip of convenient size and shape, it has been customary to glue additional central laminations to the lamination making up the belly of the bow.

This arrangement has necessitated tapering the additional laminations to exposed feather edges; the glued joints at the feather edges of the added laminations inevitably are regions of weakness in the completed structure. The central portion of a bow is placed under great compressive stresses when the bow is bent or drawn, which compressive stresses must be resisted by the glued joints between the additional laminations and the main laminations. Also, when an arrow is released, the tips of the bow may bend away from the user far enough momentarily to imPOSe severe tensile and shearing stresses on the glued joints of the additional laminations. This is particularly apt to occur if the bow string should break, for then there is nothing to restrain the movement of the tips of the bow under th'e influence of their own inertia, except the structure of the bow itself. Thus, in the event of breakage of the bow string of an ordinary laminated bow, failure is apt to occur at the glued joints near the central portion of the bow and particularly at the feathered end portions of the additional lamination or laminations. Furthermore, the glued joints necessary to secure the laminations are difficult to make, and the laminations must be feathered accurately and assembled carefully, with the result that the manufacturing operations are rath'er expensive.

According to the present invention, the difculties heretofore encountered with laminated bows are eliminated by extending the lamination on the front face or belly of the bow either continuously throughout that face, or from the ends of the bow to a point at or near the center of the bow where substantially no deflection takes place; and in order to obtain the requisite strength and stiffness in the central portion as well as to provide a convenient h'and grip, a iiller block is interposed between the front and rear laminations, spacing them a substantial distance apart at the center of the bow.

A bow made according to a preferred form of the invention is illustrated in the drawings wherein Figure 1 is a side elevation of a bow embodying the invention, the bow being made up or strung; Figure 2 is a similar elevation showing the shape of the bow when unstrung; Fig. 3 is a back elevation of a bow embodying our invention; and Figure 4 is a longitudinal sectional view on an enlarged scale, through the central portion of the bow.

In Figure 1 the bow indicated generally at I0 is sh'own in solid lines in its strung condition, the dotted lines to the right indicating the shape of the bow when it is drawn or bent. In Figure 2, the bow is not strung, and the dotted lines to the left indicate the position the tips II and limbs I2 of the bow may take momentarily if the bow string I4 should break as an arrow is discharged. As shown particularly in Figure 3, the invention is illustrated herein as adapted to a bow having a sighting window or recess l5 in the central portion I6 thereof, the window and the arrow rest II being immediately above the grip I8. The central portion I6 is thickened as shown to provide the requisite strength and stiiiness and to furnish a convenient grip. The thickness is reduced gradually in both directions, and the limbs I2 of the bow are of substantially uniform thickness and of uniformly decreasing width from the regions I9 to th'e tips. The bow preferably is provided with a. sight 20, adjustable laterally on a slide 2| mounted on track 22.

YIn order to obtain the desired characteristics in the bow, we preferably employ a laminated construction such as shown best in Figure 4. The bow is preferably built up of four laminations, the back lamination 23 being composed of a resilient wood which is strong in tension, such as hickory or bamboo, or other materials having the desired elastic qualities; the front lamination 2l, which is subject principally to compressive stresses, is preferably composed of a strong dense wood such as Osage orange or of other material having similar characteristics. 'I'he

intermediate laminations

25 and 23 are employed principally for the purpose of spacing the front and back laminations a slight distance away from the neutral axis of the bow in order to give the bow greater power with the use of the same amount of material. Thus, the intermediate laminations may be made of any reasonably strong wood, but a heavy wood should not be employed, for it is desirable to make the bow as light as possible. We have found the heart wood of yew or red cedar to be very satisfactory for this purpose.

While only the central portion is shown on an enlarged scale ir. Figure 4, it will be understood that the

laminations

23, 24, 25 and 26 are each of substantially uniform thickness throughout the bow, and the increasing flexibility of the limbs of the bow is obtained by gradually reducing the width of the limbs from the regions I3 to the tips. 'I'he necessity of providing the grip portion I8, which may be bound with twine or other suitable material as shown in the drawings, requires that the width of the central portion be reduced. It is desirable to discharge the arrow from a point as near the lateral center line of the bow as possible, and the provision of the sighting window I5 and the arrow rest I'I necessitates a furtherV reduction in the width of the central portion of the bow. If the laminations were extended through the narrow central portion of the bow with the same spacing and thickness they have in the limbs of the bow, the bow would be extremely weak at its center. Accordingly, we secure the required strength and rigidity at the central portion of the bow in spite of its reduced thickness, and also provide a convenient grip, by interposing between the intermediate laminations 25 and 26 a reinforcing or spacer member 28. This member, which is preferably composed of a strong, dense wood, which is close grained so that it will not split easily, such as walnut or beefwood, is tapered from its greatest thickness at the center of the bow to knife edges at its ends as indicated at 29. In the central Dortion the reinforcing member may have a. thickness several times as great as the thickness of the combined laminations, although those skilled in the art will appreciate that the thickness of the laminations and the thickness of the reinforcing member may be varied within reasonably wide limits. depending upon the size and strength or weight of the bow.

'I'he several laminations and the reinforcing member are glued or otherwise suitably bonded together throughout their entire contacting areas. Preferably synthetic resin glues are employed- It will be noted that while the reinforcing member tapers down to knife or feather edges at its ends, the thin and necessarily relatively weak end portions of the reinforcing member are disposed at or very near the neutral axis of the bow so that they are not subject to great stresses. Furthermore, the ends of the glued joints between the reinforcing member and the laminations are not exposed. The laminations themselves are preferably continuous either from tip to tip of the bow or from the tips toa po' t or points in the central portion of the bow here no substantial deilection takes place when the bow is in use. For example, the laminations may be broken in the grip portion of the bow so that the joints between the ends of the laminations will be covered by the binding on the grip.

With this construction, the required rigidity of the center portion of the bow is obtained by the use of a single spacing .or reinforcing member which may be glued into place securely because vit is disposed -between the laminations.

All parts of the reinforcing member are nearer the neutral axis of the bow than the laminations, for the reinforcing member extends substantially equal distances toward the back and the front of the bow, from the center line of the limbs of the bow at their juncture with the reinforcing member. Thus. the liber stresses in thereinforcing member are always less than those in the laminations with the result that there is very little likelihood of breaking the thinned ends of the reinforcing member or of destroying the bond between the reinforcing member and the laminations.

It will be noted that the surface 30 of the reinforcing member toward the back of the bow is curved in an arc such that when the bow is fully drawn the curve in the reinforced central part of the bow corresponds to the arc of the bow. Thus, as shown in the broken lines in Figure 1, when the bow is fully drawn and under greatest stress, the laminations on the back of the bow extend in continuous curves throughout the limbs and central portion of the bow with the result that there are no regions where the stresses are excessive or unusually great. The reinforcing member 23 has a straight section as at 3| on the front or belly side of the bow, and this straight portion merges into curved portions 32 which are preferably reversely curved, i. e., concave, as at 33 near the ends of the reinforcing member. The reverse curves insure that the laminations on the belly side of the bow will also be smoothly curved from the tips of the bow to the central straight portion, again as shown in broken lines in Figure 1. composed of materials especially selected to enable them to withstand the stresses to which they are subjected, and as the laminations are continuous from the tips of the bow to the thickened central portion where no substantial deflection takes place, there are no glued joints at the ends of the laminations which are subject to any great stresses. For these reasons, the likelihood of failure is minimized.

Because of their advantageous construction, bows embodying our invention are durable and not subject to failure even in the event of breakage of the bow string. Our bows can be made with the desired characteristics by the selection of the proper woods and of the proper thicknesses and by proportioning the materials in manners understood by those skilled in the art. The reinforcing or spacer member interposed between the The laminations are y laminations gives the requisite strength and rigidity to the center section of the bow even though the center section is greatly reduced in 'width in o-rder to provide a sighting window. As

the center section extends both forward and backward from the center line of the bow, the arrow rest I1 may be disposed on or close to the frontand-back center line of the bow which makes for accuracy in shooting. These advantages are coupled with economy'of manufacture, for the laminations may be of substantially uniform thickness throughout, the reinforcing member may be of one piece and there are no exposed gluedjoints or feathered edges. All of these factors contribute to thelease with which bows embodying our invention may be manufactured.

Those skilled in Athe art will appreciate that various changes and modifications may be made in the preferred form of bow described herein without departing from the spirit and scope of the invention. .It is therefore to be understood that our patent is not limited to the preferred vform described herein or in any manner other than by the. scope of the appended claims.

We `claim:

1. An archery bow comprising a plurality of laminations including a back lamination composed of an elastic wood adapted to resist stresses in tension, a front lamination composed of a strong, dense wood adapted to resist stresses in compression and two intermediate laminations composed of a wood less dense than the Iwood of which the front lamination is composed, the laminations being continuous from the tips to at least the central portion of the bow, and a wooden reinforcing member interposed between said intermediate laminations in the central portion of the bow, the reinforcing member increasing in thickness from substantially knife edges at its ends to an intermediate thickness great enough to provide a convenient grip and to substantially increase the strength and rigidity of the central portion of the bow, said laminations and said reinforcing member being glued together throughout substantially all of their contacting areas.

2. A bow according to claim 1 wherein the back lamination is hickory` the front lamination is Osage orange,`the intermediate laminations are yew and the reinforcing member is walnut.

3. An archery bow comprising a plurality of laminations including a back lamination composed of an elastic wood adapted to resist stresses in tension, a front lamination composed of a strong, dense wood adapted to resist stresses in compression and two intermediate laminations composed of a-wood less dense than the wood of which the front lamination is composed, the front and back laminations being continuous from the tips to at leastthe central portion 0f the bow, and a wooden reinforcing member interposed between said intermediate laminations in the central portion of the bow, the reinforcing member increasing in thickness from substantially knife edges at its ends to an intermediate thickness great enough, substantially to increase the strength and rigidity of the central portion of the bow.

4. An archery bow comprising a plurality of laminations including a back lamination composed of an elastic wood adapted to resist Stresses in tension and a front lamination composed of a strong, dense wood adapted to resist stresses in compression, and a reinforcing member interposed between said intermediate laminations in the central portion of the bow, the reinforcing member having an intermediate thickness great enough substantially to increase the strength and rigidityA of the central portion of the bow.

5. An archery bow comprising a plurality of laminations, the laminations making up the limbs of the bow being continuous from the tips thereof at least to points in the central portion of the bow where no substantial deflection takes placey and a member disposed between the front and back laminations in the central portion of the bow for increasing the strength and rigidity of the central portion and providing a convenient grip, said member having a thickness at the center of the bow substantially greater than the total thickness of the laminations and tapering to feather edges at its ends. the limbs of the bow eing of substantially uniform thickness and de reasing width from the ends of member to the ti s of the bow, said laminations and said member being glued together throughout substantially all of their contacting areas.

6. An archery bow comprising a. plurality of laminations, the laminations making up the limbs of the bow being continuous from the tips thereof at least to points in the central portion of the bow Where no substantial deflection takes place, and a member disposed between the front and back laminations in the central portion of the bow for increasing the strength and rigidity of the central portion and providing a convenient grip, said member having a thickness at the center of the bow substantially greater than the total thickness of the laminations and tapering to feather edges at its ends, the limbs of the bow being of substantially uniform thickness, said laminations and said member being glued together throughout substantially all of their contacting areas.

7. An archery bow comprising a plurality of laminations, each lamination being of substantially uniform thickness throughout and a member disposed between the front and back laminations in the central portion of the bow for increasing the strength and rigidity of the central portion and providing a convenient grip, the limbs of the bow increasing in width from the tips to regions adjacent the ends of said member and the central portion being reduced in width and cut away on one side to provide a. sighting window and an arrow rest, the thickness of the limbs of the bow being substantially uniform from the tips to regions adjacent the ends of said member, the thickness of the central portion being increased by said member, and said front and back laminations being continuous from the tips of the bow at least to regions of said central portion where no substantial deflection occurs.

8. An archery bow comprising a plurality of laminations, each lamination being of substantially uniform thickness throughout and a member disposed between the front and back laminations in the central portion of the bow for increasing the strength and rigidity of the central portion, the central portion being reduced in width and cut away on one side to provide a sighting window and an arrow rest, the thickness of the limbs of the bow bein-g substantially uniform from the tips to reg-ions adjacent the ends of said member, the thickness of the central portion being increased by said member, and said front and back laminations being continuous from the tips of the bow at least to regions of said central portion where no substantial deflection occurs.

9. An archery bow comprising a plurality of laminations and a member disposed between the front and back laminations in the central portion rest, the thickness of the central portion being increased by said member. and said front and back laminations being continuous from the tips of the bow at least to regions 0f said central portion where no substantial deflection occurs.

10. An archery bow comprising a front lamination and a back lamination, the laminations being continuous from the tips of the bow at least to points adjacent the center of the lbow and a. central reinforcing member disposed between said laminations and spacing them apart, the reinforcing member extending only through the central portion of the bow where no substantial deflection occurs and tapering in both directions from a relatively thick center to very thin edges at its ends, the said thin edges being disposed substantially on the neutral axis of the bow.

11. A bow according to claim 10 wherein the back lamination is hickory and the front lamination is Osage orange.

12. A bow according to claim 10 wherein the 8 reinforcing member extends substantially equal distances toward the front and back of the bow from the center line of the limbs of the bow at their Junctures with said reinforcing member.

13. A bow according to claim 10 wherein the back surface of the reinforcing member is continuously curved substantially to correspond to the curve of the bow when fully drawn.

14. A bow according to claim 10 wherein the back. surface of the reinforcing member is continuously curved to substantially correspond to the curve of the bow when fully drawn, and wherein the front surface of the reinforcing member is concave adjacent its ends.

The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Hill Sept. 23, 1941 Number