Fishing rod stock and method of manufacturing same

Fishing rod stock is manufactured by winding three prepreg sheets around a mandrel to form three resin layers including high strength fibers. The first resin layer is formed over an entire axial length of the fishing rod stock. The second resin layer is formed on a rearward portion of the fishing rod stock. The third resin layer is smaller than the second resin layer and formed on a rearward region of the fishing rod stock. The high strength fiber of the second resin layer has a higher modulus of elasticity than the high strength fiber of the first resin layer. The high strength fiber of the third resin layer has a higher modulus of elasticity than the high strength fiber of the second resin layer. The high strength fibers of the second and third resin layers progressively increase in quantity toward a rear end of the fishing rod stock.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to fishing rod stock and a method of 
manufacturing the rod stock. More particularly, the invention relates to a 
method of manufacturing tubular rod stock by winding, around a gently 
tapered mandrel, prepreg formed of high strength fiber impregnated with a 
thermosetting resin, and allowing the resin to harden. Specifically, the 
invention relates to a technique of determining condition of fishing rods. 
2. Description of the Related Art 
A conventional technique of determining condition of fishing rods is 
disclosed in Japanese Patent Publication Kokai No. 62-292422, for example. 
According to the conventional technique, a mandrel having a sharply 
tapered intermediate portion is used in manufacturing fishing rod stock. 
Completed fishing rod stock has varied bending strengths based on a 
difference in diameter between a tip end portion and a butt end portion 
thereof. 
Where, as in the prior art, the mandrel used includes a sharply tapered 
intermediate portion, a desired condition of fishing rods is achieved 
relatively reliably. However, a single sheet of prepreg may be creased in 
a region corresponding to the intermediate portion of the mandrel. It is 
difficult to apply a suitable pressure uniformly over the prepreg being 
wound. The prior art method has room for improvement with respect to 
manufacturing efficiency. 
On the other hand, a fishing rod used for catching relatively large fish 
should be flexed in arcuate form with a bending force distributed 
throughout the rod when drawing a fish. This allows the angler to draw and 
land a fish with ease by using elasticity of the rod. However, a fishing 
rod formed of the rod stock having varied diameters as noted above 
includes an intermediate position presenting a change in the modulus of 
elasticity (or a change in the modulus of section) of the rod. This 
results in local bending of the fishing rod, making it difficult to flex 
the entire rod in a large arcuate form. 
Fishing rod stock may be manufactured easily by winding prepreg around a 
gently tapered mandrel. However, a rear end region of this fishing rod 
stock has insufficient flexural rigidity compared with a tip end region 
thereof. A fishing rod formed of prepreg having a uniform modulus of 
elasticity has the inconvenience of tending to bend greatly in a rear end 
region thereof. There is room for improvement in this respect also. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide fishing rod stock flexible 
in a large arcuate form to distribute a bending force throughout, and an 
improved method of manufacturing fishing rod stock which realizes a 
desired condition of fishing rods in a simple operation. 
The above object is fulfilled, according to the present invention, by 
fishing rod stock comprising a first resin layer including high strength 
fiber and formed over an entire axial length of the fishing rod stock, and 
a second resin layer including high strength fiber having a higher modulus 
of elasticity than the high strength fiber of the first resin layer, and 
formed on a rearward portion of the fishing rod stock less than the entire 
length thereof, the high strength fiber of the second resin layer 
progressively increasing in quantity toward a rear end of the fishing rod 
stock. 
This fishing rod stock has the following functions and effects. 
The above features may be arranged as shown in FIGS. 1 through 4, for 
example. The rod stock R includes a tip end portion having only a first 
resin layer 1 formed thereon. A rear portion of the rod stock R has also a 
second resin layer 2 with high strength fiber S2 progressively increasing 
in quantity toward a rear end of the rod stock R. Thus, curvature of the 
rod stock R occurring under a bending force is the smaller toward the rear 
end thereof. In addition, this rod stock R is free from marked local 
bending. 
The rod stock R according to the present invention is not formed of a high 
strength fiber having a fixed characteristic, but is formed of at least 
two types of high strength fibers S1 and S2 having different moduli of 
elasticity. Moreover, the high strength fibers are distributed in 
predetermined quantities to realize a fishing rod flexible in a large 
arcuate form in an actual fishing situation, to distribute a bending force 
throughout the rod. 
It should be noted that these drawings do not depict the variation in the 
quantity of high strength fiber S2 in the second resin layer 2. 
In a further aspect of the invention, a method of manufacturing fishing rod 
stock is provided which comprises the steps of winding around a mandrel a 
first prepreg sheet including a high strength fiber impregnated with a 
thermosetting resin, and a second prepreg sheet including a high strength 
fiber having a higher modulus of elasticity than the high strength fiber 
of the first prepreg sheet and impregnated with the thermosetting resin, 
with ends of the respective prepreg sheets placed at a large diameter 
position of the mandrel, the second prepreg sheet having a smaller size 
axially of the mandrel than the first prepreg sheet, and the other end 
thereof opposed to a small diameter end of the mandrel lying at an angle 
to an axis of the mandrel; and baking the first and second prepreg sheets 
to allow the sheets to harden into a tubular stock shape. 
This method has the following functions and effects. 
The above features may be arranged as shown in FIGS. 5 and 6, for example. 
At least two types of prepreg sheets P1 and P2 are used. The first prepreg 
sheet P1 (first resin layer 1), after baking, forms a tip end portion 
(small diameter portion) of rod stock R, with high strength fiber S1 
having a strength resistive to a bending force as in the prior art. A 
rearward portion (large diameter portion) of the rod stock R has the first 
prepreg sheet P1 and second prepreg sheet P2 (second resin layer 2) with 
the high strength fibers S1 and S2 presenting a stronger resistance to a 
bending force than in the prior art. In addition, since the high strength 
fiber S2 of the second resin layer 2 progressively increases in quantity 
toward the rear end, the resistance to a bending force is the stronger 
toward the rear end. 
That is, the present invention uses a mandrel having an approximately 
straight shape as often used heretofore, for winding the first prepreg 
sheet P1. Then, the second prepreg sheet P2 having a predetermined shape 
is wound around the first prepreg sheet P1 (though the second prepreg 
sheet P2 may be placed under the first prepreg sheet P1). This realizes 
fishing rod stock R having a desired condition, with a modulus of 
elasticity progressively increasing toward the rear end. 
The foregoing and other objects, features and advantages of the invention 
will be apparent from the following more particular description of 
preferred embodiments of the invention, as illustrated in the accompanying 
drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Fishing rod stock and a method of manufacturing the rod stock according to 
the present invention will be described in detail hereinafter with 
reference to the drawings. 
Fishing rod stock R has a construction as shown in FIGS. 1 through 4. 
The rod stock R includes a first resin layer 1 formed over an entire length 
along an axis X thereof, a second resin layer 2 formed on a rearward 
portion shorter than the entire length of the rod stock R, and a third 
resin layer 3 formed on a rearward portion smaller than the second resin 
layer 2. 
The first, second and third resin layers include high strength, carbon 
fibers. The high strength fiber S2 of the second resin layer 2 has a 
higher modulus of elasticity than the high strength fiber S1 of the first 
resin layer 1. The high strength fiber S3 of the third resin layer 3 has a 
higher modulus of elasticity than the high strength fiber S2 of the second 
resin layer 2. The second and third resin layers 2 and 3 have the high 
strength fibers S2 and S3 in quantities, as seen circumferentially, 
progressively increasing toward rear ends thereof (i.e. the resin layers 2 
and 3 being formed progressively thicker toward the rear ends). A fishing 
rod formed of this rod stock R, when drawing a fish, is flexible in a 
large arcuate form to distribute a bending force throughout an entire 
length thereof. 
Although the drawings depict the respective resin layers 1, 2 and 3 to be 
discrete, the rod stock R is in fact an integral body having the resin 
layers 1, 2 and 3 rigidly fused together. The high strength fiber S1 of 
the first resin layer 1 has a modulus of elasticity set to 24 
tons/mm.sup.2. The high strength fiber S2 of the second resin layer 2 has 
a modulus of elasticity set to 30 tons/mm.sup.2. The high strength fiber 
S3 of the third resin layer 3 has a modulus of elasticity set to 40 
tons/mm.sup.2. 
The rod stock R is manufactured in the following sequence. 
As shown in FIG. 5, a first prepreg sheet P1 is wound around a gently 
tapered mandrel 4 first. This prepreg sheet P1 forms the first resin layer 
1 after baking. 
Next, a second prepreg sheet P2, which forms the second resin layer 2 after 
baking, is wound around a large diameter portion (rearward portion) of the 
first prepreg sheet P1. In winding the second prepreg sheet P2, a position 
(tip end portion) E2 thereof opposed to a tip end portion or small 
diameter portion of the mandrel 4 is placed at an angle to an axis Y of 
the mandrel 4. 
Next, a third prepreg sheet P3, which forms the third resin layer 3 after 
baking, is wound around a large diameter portion (rearward portion) of the 
second prepreg sheet P2. In winding the third prepreg sheet P3, a position 
(tip end portion) E3 thereof opposed to the tip end portion or small 
diameter portion of the mandrel 4 is placed at an angle relative to the 
axis Y of the mandrel 4. 
The high strength fibers S1, S2 and S3 of the prepreg sheets P1, P2 and P3 
are paralleled carbon fibers impregnated with an epoxy resin. The edges E2 
and E3 of the second and third prepreg sheets P2 and P3 are inclined so 
that, after baking, the high strength fibers S2 and S3 are in quantities, 
as seen circumferentially of the rod stock R, progressively increasing 
toward the rear end. After the above sheet winding steps, a heat 
contractible tape 5 is wound as shown in FIG. 6. Then, the product is 
baked at a predetermined temperature, whereby the prepreg sheets P1, P2 
and P3 are fused together to form a tubular object. Subsequently, the 
mandrel 4 is removed, and opposite ends of the tubular object are cut, and 
a predetermined surface treatment is carried out to complete the fishing 
rod stock. 
The present invention may be modified as follows: 
(a) Two, three or more resin layers may be formed. The second resin layer 
may be formed under the first resin layer. 
Where three or more resin layers are formed, a resin layer may be formed 
under the first resin layer or over the second resin layer, or between the 
first resin layer and second resin layer. 
(b) In manufacturing the rod stock, the first resin layer may be wound 
around an outer surface of the second resin layer. 
(c) Two, three or more types of prepreg having different moduli of 
elasticity may be used. 
(d) The prepreg sheets may be wound around the mandrel independently of 
each other. 
(e) The thickness of prepreg may be adjusted to increase the high strength 
fiber of the second resin layer toward the rear end. Alternatively, the 
density of the high strength fiber in the prepreg may be adjusted for this 
purpose. 
(f) Glass fiber may be used for the first resin layer, while carbon fiber 
is used as high strength fiber for the second resin layer. 
(g) Boron fiber may be used as high strength fiber for the second resin 
layer, while carbon fiber is used for the first resin layer.