US3141451A - Archer's bow - Google Patents

Description

July 21, 1964 R. v. WALKER ARCHER'S BOW Filed sept. 1e, lseo mm, QN um. QNV Nm SW7 N@ m h\ m fm www NW wmv L mg Q United States Patent O 3,141,451 ARCHERS EGW Richard V. Walker, Glen Ellyn, and Robert W. De Land, Wheaton, Ill. (both of 838 Duane, Glen Ellyn, Ill.) Filed Sept. 16, 1960, Ser. No. 56,447 Claims. (Cl. 124-24) The present invention relates to archers bows.

The principal object of this invention is to provide a novel bow which has greatly improved characteristics as compared with other high quality bows currently available.

An additional object is to provide a novel material to be used in bow construction and a novel arrangement for making use of this material.

More specifically, it is an object to provide an improved bow which, as compared with other high quality bows, has among others the following advantageous characteristics. It is much less subject to breakage, delamination or other structural damage, and, in general, has a much longer, useful life. It does not readily get out of tiller-that is, twisted-and if it does, tiller can easily be restored. The force required to draw the bow is considerably more constant throughout the useful range. In archery parlance, the bow is thus said to have much less stack Other objects and advantages will become apparent from the following description of a preferred embodiment of our invention which is illustrated in the accompanying drawings.

In the drawings, in which similar characters of reference indicate similar parts throughout the several views,

FIG. 1 is a side view of a bow in which the present invention is embodied;

FIG. 2 is a back view of the bow as is indicated by the arrows along the line 2 2 of FIG. l;

FIG. 3 is an enlarged view of the central portion of the bow taken from the side;

FIG. 4 is a fractional side view of a material used in the bow construction;

FIG. 5 is an edge view of one of the bow limbs at an intermediate position as indicated by the arrows along the line 5-5 of FIG. 2;

FIG. 6 is a back view of one of the ends of the bow as indicated by the arrows along the line 6-6 of FIG. l;

FIG. 7 is an edge view of one of the ends of the bow as indicated by the arrows along the line 7-7 of FIG. 2; and

FIG. 8 is an edge view, similar to FIG. 5, but showing an alternative structural arrangement.

As background for this invention, it seems worthwhile to explain the general characteristics of bows of the high quality type in almost universal use at the present. Almost all such bows have a thick, stiff, central portion which serves as the hand grip, this portion usually being notched out at one side above the hand position to provide a ledge against which the arrow is rested. The limbs of the bow extend outwardly from the central portion, and usually take the form of what is known as the Turkish bow; that is, the limbs curve backwardly slightly as they extend outwardly, excepting that near the ends the limbs are recurved so as to extend slightly forwardly. The ends of the limbs are connected by the bow string which usually consists of a number of parallel cord strands bound together and reenforced by spiral wrapping at the center.

Because of the relatively recent availability of certain.

new materials, almost all quality bows have limbs of laminated construction of the following type. The forward and rearward faces of the limbs are formed of dense plastic bonded layers of woven fiberglass fabric. Although several sources are available for this material, one

lCe

source which specializes in this and other archery supplies is Bear Archery Corporation, Graling, Michigan. These fiberglass layers are glued to the opposite faces of a strip of hard maple using a glue having the following characteristics. It should form a good bond, be waterproof, have a long life, and be hard when set so as to have high physical strength. Suitable glues are supplied by several manufacturers and dealers including the above source and also by Roddis Plywood Corporation, Chicago, Illinois, as their URAC 185.

Although bows of the above type are generally considered to have the best characteristics, they are well understood to have serious limitations which, in general, it is the principal object of this invention largely to eliminate. Among the known disadvantages are the following.

Such bows have considerable stack, that is, they draw easily at the beginning, but become progressively stiffer as the drawstring is pulled rearwardly. Ideally, the drawing force should be relatively constant so as to give a uniform rate of acceleration to the arrow when the bow- String is released. Stated differently, as a specic example, if a person uses a forty pound bow it usually is because he cannot conveniently apply an appreciably greater force to the bowstring. When the bowstring is released, this forty pound force is applied to the arrow only briefly, and thereafter becomes less and less. If the drawing force were constant, the force of approximately forty pounds would be applied during the'entire time of recovery of the bow, thereby producing a much higher arrow velocity. The present invention greatly improves this situation and thus provides considerably higher arrow velocities without increasing the bow poundage. The action is also smoother and less shock is produced, which tends to improve accuracy.

Another problem which is frequent is that laminated bows are comparatively easily broken. Interestingly, breakage occurs in the maple strip, almost never in either of the glass layers. It is because of such breakage that maple is usually used, since its resistance to breakage is greater than almost any known wood which is generally available.

Such bows also frequently become delaminated through failure of the glue bond or because of thin surface layers of the maple being torn loose from the body portion. An additional problem is loss of tiller-that is, the limbs become twisted-because of warpage of the maple. Once it occurs, loss of tiller is almost always impossible to eradicate and results in a permanently defective bow.

The bow of our invention resulted from an investigation which disclosed that ordinary bows of the type discussed above present most of the difficulties mentioned because of what appears lto be a fundamental lack of appreciation of the forces involved. As the bow is drawn, the exure of the limbs generally causes the forward glass layer to be placed in tension, whereas the rearward layer is largely under the influence of compressive forces. The distribution of forces is, however, not uniform, but, as is generally said, the forward and backward layers work against each other. This produces forces in the maple intermediate layer which are compressive throughout the central portion of the limbs, but which tend to produce tensional separating effects toward the limb ends.

It is apparent, therefore, that the maple strip must resist compressive forces, which it does satisfactorily, and that the maple including the glue bond must also resist the rather strong tensional forces. This it does not do so well, although theoretically the strength would appear to be adequate.

There is an additional stress, however, that affects the above in a pronounced manner which is caused by the tendency of one of the glass layers to slip longitudinally relative to the other as the limbs are bent. This tendency toward relative slip is not constant and in fact, because of the recurved bow ends, may be in one direction throughout a portion of the bow, in the opposite direction at a different portion and have no effect at an intermediate portion. Because of the very slight amount of slipping or creeping movement thus produced, and the large lever arm which is effective,4 these forces are very large as compared with the compressive and tensional forces acting between the forward and rearward glass layers.

Inasmuch as the maple core Very strongly resists any tendency of one of its surfaces to slip relative to the other locally, the forces tending to tear loose fibers or break the glue bond, or wring the maple strip apart are more than these materials can resist under some circumstances. Furthermore, it is this effect which leads to stack, since with progressive bending of the bow the stiffening effect of the maple core becomes enormously greater because of its resistance to relative slip as between its faces.

The present invention overcomes all of these difficulties by making use of a material prepared by us which bonds extremely well to glue, which is extremely resistant in compression and tension, but which has a great ability to absorb forces producing relative slip between its faces within the limited range encountered in an archers bow.

The forward and rearward glass layers of the bow thus continue to work against each other as before, are always substantially uniformly spaced, and can slip slightly without producing excessive stresses upon or within the core material or the glue bond.

Referring to the drawings, the central portion of the bow to be grasped in the left hand is indicated by the numeral 10, and, for the purpose of describing this invention, may be considered as essentially conventional. This central portion has an arrow notch 11 and is secured to the limbs 12 which are of Turkish bow pattern, the ends being connected by a bow string 14. As in the previously discussed current conventional bow, the limbs are comprised of a forward plastic bonded liber glass layer 16 glued to a liller strip 18, glued in turn to a rearward plastic bonded Fiberglas layer 20. The Fiberglas layers and the glue may be considered to be the conventional materials previously described as in common use. The intermediate filler strip 18, however, has characteristics which are entirely different from hard maple or any other material with which we are familiar. It is constructed by us in the following manner.

A multiplicity of layers of leather-we prefer oak tanned cowhide-are stacked with glue layers between each leather layer. This stack is placed under compression until the glue has set, the resulting stack being as thick as the length of the bow limbs 12. The glue is of the type previously described which is waterproof, sets hard, has a long life, good physical strength, and which forms a good bond. Because of the fibrous nature of the leather, obtaining a good bond is no problem. In stacking the leather, we prefer to place the hair side of one hide against the inside of the next, but tests indicate that this is of no particular importance, excepting that it gives a more uniform appearing product.

This stack is then sliced by parallel cuts across the glue lines so as to produce strips from about l/s to 3/6" thick. These strips appear as in FIG. 4 where the leather pieces are shown at 22 and the glue planes at 24.

These strips are then used in place of the conventional wood layer as at 18 between the customary forward and rearward plastic bonded glass fabric strips 16 and 20. The glue 26 used for the assembly is the same as that previously described. In addition to the properties set forth above for suitable glues for bow construction, the glue should bond well with itself. All of the bow glues with which we are familiar, including those previously mentioned, have this property, but it is mentioned here as a required characteristic, since practicers of this invention may with to substitute other glues which have the desired properties.

After assembly, which can be accomplished in the usual manner, the edges of the bow are shaped and finished according to conventional practice.

A bow constructed in the described manner has properties which are a great improvement over bows of the usual laminated type. This is because the hard glue planes 24, which are closely spaced and parallel, are bonded by glue 26 to the glass strips and act as struts both in tension and in compression to maintain proper spacing between the glass layers 16 and 20. These glue struts are maintained against buckling by the leather strips 22 bonded on each side and to the glass strips, the leather strips also supplying some strength in tension and compression. Furthermore, since the leather elements are slightly pliable, local longitudinal relative movement of a small order is possible between the inner and outer faces of the composite glue and leather strip without subjecting this filler element to racking forces of a high order as is true with wood strips are explained above.

Since the two glass layers can work against each other without interference from the filler strip, the bow has much less stack and a considerably faster recovery. Also, the composite leather and glue ller has very little resistance to bending and is dead in its action, so there is essentially no rebound or vibration when the bow string snaps tight. It will be appreciated also that the filler cannot warp and twist the bow limbs. Bows incorporating this invention therefore remain in tiller even with pronounced changes in humidity over long periods. If tiller does become lost, it can easily be restored by notching the end of the limb affected slightly deeper on one side so as to shift the center of action of the end of the bow string to the left or right as required.

For very powerful bows, commonly called flight bows,

a minor variation is useful. This variation is illustrated in FIG. 8, and consists of the use of thin supporting struts 28 having glue 30 on each side in place of the glue struts 24 alone between leather strips 32. The compressive and tensional forces that can be resisted by the filler strip are therefore higher. Such a filler strip may be formed by stacking leather hides with interleaved glue and hard maple strips of the order of 1&4 to 1/32" thick and then slicing off filler strips across the glue lines in the manner previously described.

' In both these embodiments there is the essential feature that there are closely spaced thin, strong, parallel, transverse struts each of which lies in a plane normal to the forward and rearward bow faces, and that these struts are well bonded to the glass forward and rearward bow elements and to the somewhat pliable fibrous leather strips which reenforce the structure and limit the movement of the struts and prevent their collapse or breakage.

Under some conditions, it is desirable to stiften the bow ends somewhat. This can be accomplished by inserting and gluing in place a very thin tapered maple wedge 34 at the extreme end of each limb between the outer glass layer 16 and the filler strip 1S. Such a wedge is shown in FIG. 7. Whether it is needed depends largely upon how much the limb ends are reduced in width and thus weakened relative to more inwardly portions of the limbs.

From the above description of a preferred embodiment of our invention it will be apparent that certain modifications may be made in the structure without departing from the scope or spirit of the invention, and that the scope of this invention is to be determined from the scope of the following claims.

Having described our invention, what we claim as new and useful and desire to secure by Letters Patent of the United States is:

l. An archers bow comprising, means providing a central hand grip portion, a pair of limbs extending outwardly from said central portion, each of said limbs including a major portion comprised of a thin forward layer formed of a hard, dense, springy material having substantially the physical characteristics cf glass fiber reinforced plastic, a thin rearward layer having substantially the characteristics of the forward layer, a multiplicity of parallel stil struts lying between said layers and extending transversely of the limbs, a multiplicity of slightly resilient members comprised of strips of leather lling the spaces between said struts, said layers, said struts and said filling members being bonded together into a unitary structure.

2. An archers bow comprising, means providing a central hand grip portion, a pair of limbs extending outwardly from said central portion, each of said limbs including a major portion comprised of a forward layer of plastic reenforced glass liber material, a rearward layer of plastic reenforced glass liber material and an intermediate layer of filler material, said layer of liller material being glue bonded to both said glass fiber layers, said layer of liller material comprising a multiplicity of strips of leather extending transversely of said limbs, said leather strips being glue bonded together and the glue providing all of said bonds having the characteristics of setting to form a hard, structurally strong lilm, being waterproof, and providing good adhesion to itself, to leather, to the reenforced glass fiber material, and to the material of said central portion.

3. An archers bow comprising, means providing a central hand grip portion, a pair of limbs extending outwardly from said central portion, each of said limbs including a major portion comprised of a forward layer of plastic reenforced glass liber material, a rearward layer of plastic reenforced glass liber material and an intermediate layer of liller material, said layer of liller material being glue bonded to both said glass fiber layers, said layer of liller material comprising a multiplicity of strips of leather extending transversely of said limbs interleaved with hard structurally strong strips glue bonded to the leather strips, said hard strips being thin as cornpared with the leather strips, the glue providing all of said bonds having the characteristics of setting t0 form a hard, structurally strong lilm, being waterproof, and providing good adhesion to itself and to the contiguous materials, said hard strips constituting struts maintaining the spacing between said forward and rearward glass layers, and the leather strips supporting and maintaining the positions of the hard strips.

4. An archers bow comprising, means providing a central hand grip portion, a pair of limbs extending outwardly from said central portion, each of said limbs including a major portion comprised of a forward thin layer of plastic reenforced glass fiber material, a rearward thin layer of plastic reenforced glass liber material and an intermediate layer of filler material Which is thicker than said glass layers, said layer of liller material being glue bonded to both said glass fiber layers, said layer of liller material comprising a multiplicity of strips of leather extending transversely of said limbs, said leather strips having a Width equivalent to the leather thickness and being glue bonded together, and the glue providing all of said bonds having the characteristics of setting to form a hard, structurally strong iilm, being waterproof, and providing good adhesion to itself, to leather, to the reenforced glass liber material, and to the material of said central portion.

5. An archers bow comprising, means providing a central hand grip portion, a pair of limbs extending outwardly from said central portion, each of said limbs including a major portion comprised of a forward thin layer of plastic reenforced glass liber material, a rearward thin layer of plastic reenforced glass liber material and an intermediate layer of liller material which is thicker than said glass layers, said layer of liller material being glue bonded to 'both said glass liber layers, said layer of liller material comprising a multiplicity of strips of leather extending transversely of said limbs interleaved with dense strong wood strips glue bonded to the leather strips, said wood strips being of the order of 1/64, to 1/32 thick and thin as compared with the leather strips, the glue providing all of said bonds having the characteristics of setting to form a hard, structurally strong film, being waterproof, and providing good adhesion to itself and to the contiguous material, said wood strips constituting struts maintaining the spacing between said forward and rearward glass layers, and the leather strips supporting and maintaining the positions of the wood strips.

References Cited in the lile of this patent UNITED STATES PATENTS 1,756,993 Rahr May 6, 1930 2,361,527 Bacon Oct. 31, 1944 2,730,367 Bublik Jan. 10, 1956 2,894,503 Pierson v July 14, 1959 2,945,488 Cravotta July 19, 1960

Claims (1)

1. AN ARCHER''S BOW COMPRISING, MEANS PROVIDING A CENTRAL HAND GRIP PORTION, A PAIR OF LIMBS EXTENDING OUTWARDLY FROM SAID CENTRAL PORTION, EACH OF SAID LIMBS INCLUDING A MAJOR PORTION COMPRISED OF A THIN FORWARD LAYER FORMED OF A HARD, DENSE, SPRINGY MATERIAL HAVING SUBSTANTIALLY THE PHYSICAL CHARACTERISTICS OF GLASS FIBER REINFORCED PLASTIC, A THIN REARWARD LAYER HAVING SUBSTANTIALLY THE CHARACTERISTICS OF THE FORWARD LAYER, A MULTIPLICITY OF PARALLEL STIFF STRUTS LYING BETWEEN SAID LAYERS AND EXTENDING TRANSVERSELY OF THE LIMBS, A MULTIPLICITY OF SLIGHTLY RESILIENT MEMBERS COMPRISED OF STRIPS OF LEATHER FILLING THE SPACES BETWEEN SAID STRUTS, SAID LAYERS, SAID STRUTS AND SAID FILLING MEMBERS BEING BONDED TOGETHER INTO A UNITARY STRUCTURE.

Images