WO1997045173A2

WO1997045173A2 - Composite golf club shaft and method for its manufacture

Info

Publication number: WO1997045173A2
Application number: PCT/US1997/009022
Authority: WO
Inventors: Al Jackson
Original assignee: Al Jackson
Priority date: 1996-05-31
Filing date: 1997-05-30
Publication date: 1997-12-04
Also published as: JP2002503977A; WO1997045173A3; AU3216397A; JP3370341B2

Abstract

An improved composite golf club shaft (10) and method for its manufacture, and an improved club incorporating the shaft (10). The shaft includes a first elongate segment (40) for mounting the golf club head (80) and a second elongate frustoconical segment (52) for gripping. The first segment (40) is formed by wrapping sheet material around a substantially cylindrical mandrel (100), and the second elongate frustoconical segment (52) is formed therearound to produce a smoothly tapering exterior surface of the shaft (10) having an abrupt interior region of joinder (68) between the segments (40, 52). Such joinder (68) preferably is approximately one-third of the way between the gripping end and the head-mounting end of the shaft. The shaft (10) tapers such that its head-mounting end is less than approximately one-third the diameter of the gripping end. Greatly improved torque and drive distance are achievable with a club made with the shaft (10). The shaft is also lighter and capable of being used without the addition of a grip. As a result, the balance point of the club is much closer to the head of the club than before possible, further improving the performance characteristics of the club.

Description

COMPOSITE GOLF CLUB SHAFT

AND METHOD FOR ITS MANUFACTURE

Cross-Reference to Related Applications

This application claims priority from U.S. provisional patent

applications Serial No. 60/018,882, entitled "Composite Golf Club Shaft and

Method for Its Manufacture," filed on May 31 , 1996 and Serial No.

60/023,488, entitled "Composite Golf Club Shaft and Method for Its

Manufacture," filed on August 9, 1996, and U.S. non-provisional patent

application Serial No. 08/709,269, entitled "Composite Golf Club Shaft and

Method for Its Manufacture," filed on September 6. 1996. Each of these

applications is incorporated herein by reference.

Background and Summary of the Invention

This invention relates generally to golf club shafts. More particularly,

it concerns an improved composite shaft and a method for its manufacture,

and a club made with such a shaft.

Recent advances in golf shaft manufacture involve the use of carbon-

or boron-based resin-impregnated sheet material in a wrapped laminar

structure. The structure forms a thin-walled but very strong, slightly

frustoconical, but substantially cylindrical shaft. It has been found that such a

shaft delivers excellent torque transmission from the hands of a golfer holding

the shaft at one end to a golf club head mounted on the other end, when the

shaft is gripped and swung. Such golf shaft structure and method are described and illustrated in U.S. Patent Application Serial No. 08/366,965,

filed December 30, 1994, now U.S. Patent No. 5,569,099, entitled GOLF

CLUB SHAFT AND LAMINAR STRUCTURAL ELEMENT AND

METHOD FOR ITS MANUFACTURE, incorporated herein by reference.

Briefly, the invented golf club shaft includes a first elongate segment

for mounting to a golf club head, formed by wrapping sheet material around a

substantially cylindrical, very slightly tapered and thus slightly frustoconical

mandrel, and a second elongate approximately frustoconical segment for

gripping by a golfer. The second segment is formed around the first segment

and mandrel to produce a smoothly tapering exterior surface of the shaft. The

shaft thus has a bugle or horn shape with a curvilinear flare at its gripping

end, and an abrupt interior region of joinder between the segments. The

joinder between the segments preferably is approximately one-third of the

way from the gripping end of the shaft. The shaft tapers such that its head-

mounting end is less than approximately one-third the diameter of its gripping

end. Greatly improved torque transmission and drive distance are achievable

due to the structure of the shaft, even over that described in the above-

referenced US Patent No. 5,569,099.

The shaft also appears to exhibit shock-dampening properties, and

includes an ergonomically designed gripping end, both properties allowing

the shaft to be used without the conventional addition of a grip. The

elimination of the grip, which usually is made of an elastomer, significantly lightens the gripping end, dramatically changing the balance of a club made

with the invented shaft. The balance point of a club made with the invented

shaft is very close to the club head, even when the club head is quite

lightweight. The elimination of the grip also improves the torque

characteristics by eliminating the elastomeric grip flexing between the shaft

and the golfer's hand. The shape and smooth, hard surface of the gripping

end allows for a great variety of performance enhancing techniques, by

applying padding, adhesives and lubricants to selected portions of a golfer's

hands.

These and additional objects and advantages of the present invention

will be understood more readily after a consideration of the drawings and the

detailed description of the preferred embodiment.

Brief Description of the Drawings

Fig. 1 is an isometric view of a golf club, including a shaft made in

accordance with the preferred embodiment and a golf club head attached to

the shaft.

Fig. 2 is an enlarged, fragmentary, cross-sectional view of the shaft

taken generally along line 2-2 in Fig. 1.

Fig. 3 is a greatly enlarged cross-sectional view of the shaft taken

generally along line 3-3 in Fig. 1 , also shown without the head.

Fig. 4 is a front view of a partially completed golf club shaft made in

accordance with its preferred embodiment, shown before the application of an exterior coating, enlarged relative to Fig. 1, and with slightly different

dimensional proportions from the shaft shown in Fig. 1.

Fig. 5A is a front view similar to that shown in Fig. 4, illustrating the

preferred method of manufacturing the invented golf club shaft.

Fig. 5B is a front view similar to that shown in Fig. 5A, illustrating

alternative methods of manufacturing the invented golf club shaft.

Fig. 6 is an enlarged cross-sectional view of an end cap for use in the

shaft, viewed similarly to Fig. 4, and further enlarged.

Fig. 7 is a fragmentary front view of a golf club similar to the club

shown in Fig. 1 , greatly enlarged, with a portion of the shaft omitted as

indicated.

Detailed Description of the Preferred Embodiment

Referring first to Figs. 1 , 2 and 4, the invented golf club shaft is

indicated generally at 10 in the form of an elongate, hollow, horn-shaped,

curvilinearly flared but generally cylindrical body. Shaft 10 is defined by a

first end 12 that serves as a head-mounting end 12, a second end 14 that

serves as a gripping end or end region 14, and an exterior surface 16. Exterior

surface 16 preferably is a hard glossy surface smoothly tapering from a

head-mounting end outer diameter 18 to a gripping end outer diameter 20.

An intermediate outer diameter 22 is indicated between head-mounting end

12 and gripping end 14. Shaft 10 is formed with a thin wall indicated in Fig. 2 at 24, having a wall thickness 26 (see Fig. 2) and an overall axial length 28

(see Fig. 4).

Turning to Figs. 3 through 5 A, shaft 10 preferably is made of a

composite material including a plurality of laminar sheet material-type plies

(identified below). The composite material preferably is formed of flexible

fibers based on a chemical element selected from a group including boron,

tungsten, iron, and carbon. When the chemical element includes carbon, the

carbon is typically hexagonally crystallized, and is known as graphite. For

example, the material may comprise graphite-based, binder-containing, heat-

settable fibers formed into a sheet with a predefined, uniform orientation of

the fibers in the sheet. Such a sheet optimally may be oriented relative to the

long axis of shaft 10 to orient the fibers contained in the sheet to provide the

desired structural characteristics for shaft 10.

The selective orientation of the fibers in the material in the preferred

embodiment is best understood with reference to Fig. 5 A, showing the

material in layered sheets or plies, before it is formed into the shaft shape of

shaft 10. It will be seen that the plies are grouped into two discrete segments.

The plies may be characterized by the orientation or bias of the fibers in the

plies, relative to the longitudinal axis of the plies. Those plies in which the

fibers are aligned with the longitudinal axis are referred to herein as

longitudinally oriented plies, and those plies in which the fibers extend at an angle to the longitudinal axis are referred to as angularly oπented or biased

plies.

Preferably, the plies alternate between angularly biased plies and

longitudinally oriented (unbiased) plies. For example, in a first segment 30,

shown in the lower portion of Fig. 5 A, the plies include an angularly biased

ply 31 , an adjacent longitudinally oriented ply 32, another angularly biased

ply 33 adjacent ply 32, and finally another longitudinally oπented ply 34. It

will be seen that the fibers in angularly biased plies 31 and 33 are shown at

mirrored angles to each other. The preferred angle of the fibers in plies 31

and 33 is approximately 45-degrees to the longitudinal axes of the plies,

which also means that the fibers in ply 31 are perpendicular to the fibers in

ply 33.

A similar fiber arrangement is found in a second segment 35. Thus,

the plies include an angularly biased ply 36, a longitudinally oriented ply 37,

another angularly biased ply 38, and another longitudinally oriented ply 39.

Longitudinally oriented ply 37 is immediately intermediate angularly biased

plies 36 and 38. The fibers in angularly biased plies 36 and 38 are mirrored

similar to plies 31 and 33, but the angular bias is such that the fibers are

oriented at approximately a 60-degree angle to the longitudinal axes of the

plies. This means that the fibers in plies 31 and 33 are closer to alignment

with the longitudinal axes of the plies than are the fibers in plies 36 and 38.

When the plies are formed into a finished shaft, as described below, it will be seen that the longitudinal axes of the plies are axially oriented relative to the

shaft.

By dividing all of the plies of the composite material into two discrete

segments of substantially continuous fibers, as opposed to continuous fibers

running substantially the entire length of shaft 10, it has been found that the

resulting club made with shaft 10 is much more responsive than a

conventional club. It is believed that shaft 10 better resists both flexure and

torsion.

The laminar structure of an alternative embodiment is demonstrated in

Fig. 5B. A single overlapping ply with substantially continuous fiber,

extending the entire length of shaft 10 is indicated at 134, replacing

longitudinally oriented plies 34 and 39 in segments 30 and 35, respectively.

Yet another alternative embodiment, not shown, would incorporate plies 34

and 39 of segments 30 and 35 in addition to overlapping ply 134.

Overlapping ply 134 adds substantially continuous fibers extending the entire

length of the alternative shaft, and thus changes the dynamics of shaft 10 so

that it is somewhat less responsive. However, this alternative shaft also is

more forgiving, and thus offers some desirable characteristics for some

players and situations.

In Figs. 1, 2, and 4, shaft 10 will be seen to have several segments or

portions that correspond to changes in the taper or contour of exterior sur ^"

16, and correspond to the segments of plies of the composite material, just described. A first elongate segment, or portion 40, is shown in Fig. 1 as

having a first frustoconical contour defined by very small (less than 0.5-

degrees) first angle of taper indicated at 42 in Fig. 4. Given the small degree

of taper of first segment 40, it will be referred to herein occasionally as

substantially cylindrical, despite the fact that it is actually slightly

frustoconical. This provides a convenient way to describe first segment 40

relative to other more highly tapered segments of shaft 10, described below.

First segment 40 has an axial length 44 (see Fig. 4), at one end of which is a

smaller annular edge region 46, and at the other end of which is a larger

annular edge region 48. Edge region 46 corresponds to outer diameter 18,

shown in Fig. 1. For reference, a final inner diameter 50 is indicated in Fig. 2,

corresponding to edge region 48 of segment 40.

A second elongate segment or portion of shaft 10 is indicated at 52 in

Fig. 1. Second segment 52 includes a second frustoconical contour

substantially defined by a second angle of taper 54 of approximately 0.5

degrees, shown in Fig. 4. Second segment 52 has an overall axial length 56,

and further includes a subsegment or subportion 58 (see Fig. 1) that forms an

annular edge region of second segment 52. Similarly, subsegment 58 has a

third contour defined by a third angle of taper 60 of approximately 2 degrees,

and an axial length indicated at 62. The third contour renders shaft 10

somewhat bugle or horn shaped. For reference, an initial inner diameter 64 is

indicated in Fig. 2 for second segment 52, and an intermediate outer diameter 66 is indicated in Fig. 1. Intermediate outer diameter 66 corresponds to the

beginning of subsegment 58. The end of subsegment 58 corresponds to

gripping end outer diameter 20, discussed above.

Referring collectively to Figs. 1 and 5A, it will be seen that first

segment 40 corresponds to plies 31 through 35 , and second segment 52

corresponds to plies 36 through 39, with some overlap of first segment 40 by

second segment 52. The change in contour from segment 40 to segment 52 is

believed to complement the discrete segments of fibers, making shaft 10 even

more responsive, and to isolate a golfer holding end 14 from vibrations

generated at end 12. A transition region 68 is indicated in Fig. 1 by the

joinder of first segment 40 and second segment 52, and is in the form of a

smoothly tapering blended joint, when viewed from the exterior of shaft 10.

Thus, transition region 68 corresponds to the joint between the plies of first

segment 40 and second segment 52. Transition region 68 includes an interior

region of joinder with an abrupt step increase in inner diameter, indicated at

70 in Fig. 2. The axial length of transition region 68 is indicated in Fig. 4 at

72.

Annular edge region 58 of second segment 52 may be capped with an

end cap 74, formed from cork or other resilient material. As shown in Fig. 6,

end cap 74 preferably has an axial length indicated at 76 and a hollow core

78. For reference, a golf club head 80 is shown in Figs. 1 and 7, and

includes a bottom surface indicated at 82. A center of mass for head 80 is

indicated at 80a in Fig. 7. Shaft 10 and head 80 together form a finished golf

club 84. A center of mass 84a for finished golf club 84 is indicated in Fig. 7.

The shock-isolating feature of shaft 10 eliminates the need for a

conventional grip. This improves the responsiveness of club 84 by

eliminating the flexure and torsion that is found in the elastomeric grips of

conventional clubs. It also eliminates the weight of a grip, which

conventionally is at the gripping end of club 84, making the club much lighter

than a conventional club and moving the balance point of club 84 much closer

to the head (and thus lower to the ground when club 84 is in use) than in a

conventional club. This is the case even when head 80 is much lighter than

normal. It has been found that lighter clubs with lower balance points,

measured relative to a ground plane in normal playing position, often perform

better than clubs with higher balance points.

Furthermore, the above-discussed aspects of second segment 52,

including the changes in contour and smooth-glossy surface 16 allow for the

use of numerous performance-enhancing compounds and articles other than a

shaft-mounted grip. For example, a golfer may find that wearing a glove on

one hand, while applying some lubricant to the other hand allows the gloved

hand to exert the majority of the control over the club. Similar results might

be achieved by using an adhesive on one hand, and not on the other. Further fine-tuning might include the use of adhesive or lubricant just on one portion

of a hand.

A more detailed explanation of the dimensions of shaft 10 and the

relationship of shaft 10 to club head 80 in finished golf club 84 is aided by the

following identifications, as shown best in Fig. 7. A longitudinal axis 86 is

indicated for shaft 10, and a ground plane 88, based on the normal playing

orientation of club 84, is shown, with ground plane 88 being approximately

tangential to a portion of bottom surface 82. A ground-based balance point

distance 90 is defined from club center of mass 84a to bottom surface 82,

taken perpendicularly from ground plane 88, as shown by the dimension

callout lines in Fig. 7. An overall length of club 84 is indicated at 92,

measured from the top of shaft 10 to bottom surface 82, taken along

longitudinal axis 86 by projection, also shown by dimension callout lines in

Fig. 7. An alternative measurement of the balance point is indicated in Fig. 7,

showing an axial balance point distance 94 measured by projection of both

center of mass 84a and bottom surface 82 onto axis 86, and measuring the

axial distance between these projected points, as shown. Finally, a gripping

region is indicated at 96, corresponding generally to the region of shaft 10

having a frustoconical contour defined by second angle of taper 54. A

midpoint of gripping region 96 is indicated at 98.

Thus, club 84 could be described as follows. Club 84 includes a shaft

10 and a golf head 80. Shaft 10 has a longitudinal axis 86. Head 80 includes a bottom surface 82 opposite from shaft 10, bottom surface 82 defining a

ground plane 88 approximately contacting bottom surface 82 and extending at

an angle 88a of approximately 50-degrees from longitudinal axis 86. A

ground-based balance point distance 90 is defined between club center of

mass 84a and bottom surface 82, measured along a line projecting

perpendicularly to ground plane 88, as indicated by dimensional line 90.

Alternatively, an axial balance point distance 94 is defined between center of

mass 84a and bottom surface 82, measured along longitudinal axis 86 by

perpendicular projection, as shown by dimensional line 94.

Preferably, club 84 has an overall weight of less than approximately

400-grams and an overall length of at least 42-inches. Shaft 10 has a shaft

weight and head 80 has a head weight and the ratio of the head weight to the

shaft weight is more than approximately 3-to-l . More specifics on the

weights of shaft 10, head 80, and club 84 are given in the tables below.

The above-defined axial length, inner and outer diameters, angles of

taper and choice of fibers may be varied to produce various shafts 10 for use

in different-purpose golf clubs. For example, a smaller diameter shaft might

be used by players with smaller hands. Conversely, a larger diameter shaft

might be used by players with large hands or with arthritis. In general, first

segment 40 is approximately two-thirds of overall shaft length 28 of shaft 10,

and second segment 52 is approximately one-third of overall shaft length 28. Second segment 52 ranges from approximately 10.5-inches to 16-inches in

length. The following table lists more specific dimensions for selected clubs.

The following table lists results from robotic tests of two clubs made from

the invented shaft (New "Firm" and New "Strong"), as well as two clubs made

from other shafts (B.B. UL "Firm" and A.J. Tech(tm) 2590 XKD). Each club

was swung with the same force, hitting a ball with the center of the face of the

head, and the results show selected measurements from a series of 8 hits with

each club. The average value is listed, as indicated by "avg.," and standard

deviation is listed for distance and velocity, indicated by "s/d." Dispersion

measures the amount of variation from straight-line travel of the ball, whether

airborne or total. The airborne distance is the point-to-point distance from the tee

to the first landing of the ball. Swing weight is a standardized measurement for

golf clubs, reflecting the "feeling" of the club by measuring the static balance

leverage of the club.

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Given the above identification of the various aspects of a golf club,

different embodiments of the invention may be described. For example, one

embodiment may be described as a shaft 10 having two distinct elongate

segments 40 and 52. First segment 40 is substantially cylindrical and extends

from a first end 12 for mounting of a golf club head 80, to a second end 48.

Second segment 52 is substantially frustoconical and extends coaxially with first

segment 40. A first end of second segment 52 is joined with second end 48 of

first segment 40. A second end 14 of second segment 52 is provided for manual

gripping by a user.

First segment 40 preferably is approximately twice as long as second

segment 52, although the ratio of the two segments 40 and 52 may vary

somewhat within the spirit and scope of the invention, as shown in the

differences between Figs. 1 and 4. First segment 40 and second segment 52 meet

in a region of joinder 68. Inner diameters 50 and 64 of segments 40 and 52 are

substantially different, as shown in Fig. 2. Segments 40 and 52 have

substantially identical outer diameters in region 68.

A different embodiment may be described as a shaft 10 for attachment at

a first end 12 to a golf club head 80, wherein shaft 10 is defined by an exterior

surface 16 having a first contour over a first portion 40 of shaft 10 adjacent first

end 12 and a second contour over a second portion 52 of shaft 10 distant from first end 12, wherein the contour of second portion 52 flares relative to the

contour of first portion 40.

Preferred Method of Manufacturing the Preferred Embodiment

The preferred method for manufacturing shaft 10 includes steps to create

a laminated first segment 40 for shaft 10. These include the steps of selecting

graphite-based oriented fiber sheet material, cutting from the sheet material a first

elongate rectangular biased ply 31 (one in which the ply is cut from the sheet

material relative to the fiber orientation in the sheet material so that the fibers in

the resulting ply extend at an angle to the long axis of the rectangle defined by

the ply), cutting from the sheet material an elongate rectangular intermediate

longitudinally oriented ply 32 (one in which the fibers extend parallel to the long

axis of the rectangle defined by the ply), and cutting from the sheet material a

second elongate rectangular biased ply 33 . Intermediate ply 32 is sandwiched

between first biased ply 31 and second biased ply 33 and the fibers in first ply 31

are oriented to extend at an angle approximately perpendicular to the fibers in

second biased ply 33. The fibers in plies 31 and 33 are oriented to define an

angle of approximately 45-degrees to the long axis of the rectangular plies.

Preferably, an outer longitudinally oriented ply 34 similar to intermediate ply 32

is applied to second biased ply 33. The sandwiched plies preferably are tacked

together by applying heat at selected regions. The preferred method further includes steps to create a laminated second

segment 52 attached to first segment 40. For example, the method includes the

steps of selecting boron-based oriented fiber sheet material, and cutting from the

sheet material plies similar to those defined for use in forming first segment 40.

A first elongate rectangular biased ply 36 is cut, an elongate rectangular

intermediate ply 37 is cut, and a second elongate rectangular biased ply 38 is cut.

Preferably, the fibers in biased plies 36 and 38 are oriented to be closer to

alignment with the short sides of the rectangular ply than to its long sides,

defining an angle of approximately 60-degrees to the long axis of the rectangular

ply, as shown in Fig. 5 A. The fibers in first ply 36 are oriented approximately

opposite (or mirrored) to the fibers in second ply 38. In Fig. 5B, the angles of

plies 36 and 38 are shown at an alternative angle of 30-degrees to the long axis of

shaft 10.

The long axes of rectangular plies 36, 37 and 38 will be aligned with

longitudinal axis 86 in the finished shaft 10. Intermediate ply 37 is sandwiched

between first ply 36 and second ply 38. Preferably, an outer longitudinally

oriented ply 39 similar to intermediate ply 37 is applied to second ply 38. The

sandwiched plies preferably are tacked together by applying heat at selected

regions.

The method further includes the step of interposing a portion of

boron-based first ply 36 between graphite-based intermediate ply 32 and second ply 33. The boron-based plies are tacked to the graphite-based plies by applying

heat to selective regions of overlap between the plies. The regions of overlap

increase the structural integrity of the joint between first segment 40 and second

segment 52, while maintaining the discrete segments of plies, discussed above.

A mandrel 100 is formed having predefined regions of a first taper, a

second taper greater than the first taper, and a third taper greater than the second

taper, and the graphite-based sheet material is rolled onto mandrel 100 to form

substantially first segment 40. Further rolling of the sheet material onto mandrel

100 rolls the boron-based sheet material around mandrel 100, thus lapping first

segment 40 with additional sheet material to form substantially second segment

52. The preferred alignment of the fibers in plies 31, 33, 36, and 38 results in a

shaft 10 having angularly biased plies in first segment 40 and second segment 52,

with fibers in first segment 40 being closer to axial alignment than the fibers in

second segment 52. The rolled and overlapped sheet material, including plies 31,

32, 33, 34, 36, 37, 38, and 39 are set or cured in a vacuum autoclave as will be

understood by those having skill in the art. The resulting shaft preferably is

coated with any suitable coating 16a (see Fig. 3) to define smoothly tapering

exterior surface 16 and to produce an integral shaft 10.

The preferred method may be varied in numerous ways to produce an

alternative embodiment of shaft 10, each embodiment having the geometry

defined above and incorporating material properties as desired. For example, the sheet material may be selected having fibers based on compounds other than

graphite or boron, such as glass or tungsten. The grouping of graphite- and

boron-based fibers described above may be altered so that segment 40 is boron-

based and segment 52 is graphite-based. Further, each ply in the sheet material

may be selected to include fibers based on compounds different from the fibers in

any other ply in shaft 10. Still further, the selection of oriented fiber ply may be

replaced or augmented by helical or longitudinal winding of fibers about or along

mandrel 100, as is understood by those having skill in the art. Yet further, an

alternative method may include the steps of cutting from the graphite-based sheet

material an elongate rectangular overlapping ply 134 in which the fibers are

longitudinally oriented, and rolling overlapping ply 134 around first segment 40,

second segment 52, and mandrel 100 to overlap first segment 40 and second

segment 52. In yet another alternative embodiment, the step involving

overlapping ply 134 may replace the steps involving plies 34 and 39.

Described differently, a method for manufacturing a golf club shaft

includes rolling laminar sheet material, such as plies 31 , 32, and 33, onto a

mandrel 100 to produce a first shaft segment 40 that is substantially cylindrical

and slightly tapered throughout its length. Shaft segment 40 terminates on either

end in an annular edge region, 12 and 48. Slightly smaller annular edge region

12 is adaptable to mount a golf club head 80. First shaft segment 40 is lapped in slightly larger annular edge region 48

with additional laminar sheet material, such as plies 36, 37, and 38, to produce a

second shaft segment 52 that is substantially frustoconical. Second shaft

segment 52 extends axially with first shaft segment 40 and to a predetermined

length therebeyond. The lapping is performed in such manner that there is a

smoothly tapering transition region 68 along the exterior surfaces of first and

second shaft segments, 40 and 52.

The predetermined length is formed by rolling the additional sheet

material onto mandrel 100. The predetermined length terminates in an annular

edge region having a diameter that is substantially greater than annular edge

region 46 of first shaft segment 40. The sheet material of first and second shaft

segments 40 and 52 is set or cured to produce an integral shaft 10 of determined

length.

While the present invention has been shown and described with reference

to the preferred embodiment, it will be apparent to those skilled in the art that

other changes in form and detail may be made therein without departing from the

spirit and scope of the invention as defined in the appended claims.

Claims

I CLAIM:

1. A shaft for a golf club, the shaft comprising:

two overlapped elongate segments,

with a first of the two segments being slightly frustoconical and extending

from a first end of said first segment for mounting of a golf club head to a second

end of said first segment,

with a second of the two segments being slightly more frustoconical than said

first segment and extending approximately coaxially with said first segment, with a

first end of said second segment being joined with said second end of said first

segment, a second end of said second segment defining a region for manual gripping

by a user,

said first segment being approximately twice as long as said second segment,

said first and said second segments in a region of their joinder with one

another having different inner diameters and having substantially identical outer

diameters.

2. The shaft of claim 1, wherein said shaft is formed first by forming said

first segment and second by forming said second segment around said first segment

in the region of said second end of said first segment.

3. The shaft of claim 1 , wherein said shaft at said second end of said

second segment has an outer diameter between approximately three and four times

an outer diameter of said first end of said first segment.

4. The shaft of claim 1, wherein said shaft at said second end of said

second segment has an outer diameter between approximately one-and-one-half and

two-and-one-half times an outer diameter of said first end of said first segment.

5. The shaft of claim 1 , wherein said shaft in said region of joinder has

an abrupt step increase in inner diameter and a smooth transitional increase in outer

diameter.

6. The shaft of claim 1 , wherein said shaft has substantially uniform wall

thickness throughout its substantial length.

7. The shaft of claim 6, wherein said wall thickness is approximately 1.0

millimeter.

8. The shaft of claim 1 which is formed by a laminating process.

9. The shaft of claim 8, wherein said first and said second shaft segments

are formed around one or more mandrels.

10. The shaft of claim 8 which is formed of plural fiber plies.

11. The shaft of claim 10, wherein said plural plies include oppositely

angularly biased fiber plies having interposed therebetween a longitudinally oriented

fiber ply.

12. The shaft of claim 10, wherein said plural plies include an angularly

biased fiber ply in the first segment and another angularly biased fiber ply in the

second segment, and the fibers in the ply in the first segment are closer to axial

alignment than the fibers in the ply in the second segment.

13. The shaft of claim 10, wherein said plural plies include a

longitudinally oriented fiber ply substantially overlapping both the first and second

segments.

14. The shaft of claim 10, wherein said plies are of substantially planar

flexible binder-containing sheet material.

15. The shaft of claim 14, wherein said sheet material is formed from

substantially continuous fiber material based on a chemical element selected from a

group including boron, tungsten, iron and carbon.

16. The shaft of claim 10, wherein said plural plies in the first segment

include substantially continuous fiber material based on a group including boron,

tungsten and iron, and said plural plies in the second segment include substantially

continuous-fiber material based on carbon.

17. A shaft for attachment at a first end to a golf club head, wherein the

shaft is defined by an exterior surface having a first contour over a first portion of the

shaft adjacent the first end and a second contour over a second portion of the shaft

distant from the first end, wherein the contour of the second portion flares relative to

the contour of the first portion.

18. The shaft according to claim 17, wherein the second portion has an

axial length that is approximately one-third the axial length of the shaft.

19. The shaft according to claim 17, wherein the shaft is formed from

fiber plies.

20. The shaft according to claim 17, wherein the shaft is formed with

laminar material.

21. The shaft according to claim 17, wherein the shaft is formed with

multiple plies of laminar material.

22. The shaft according to claim 17, wherein the first portion tapers at a

first angle, and the second portion tapers at a second angle greater than the first

angle.

23. The shaft according to claim 17, wherein the second portion is layered

on top of the first portion to form a blended joint, smoothly transitioning the exterior

surface from the first portion to the second portion.

24. The shaft according to claim 23, wherein the joint has an axial length

that is between approximately one-tenth and one- fifth the axial length of the second

portion.

25. The shaft according to claim 17. wherein the second portion includes a

subportion at a second end of the shaft, the subportion having a third contour that

tapers relative to the contour of the second portion.

26. The shaft according to claim 25, wherein the subportion has an axial

length that is approximately one-tenth the axial length of the second portion.

27. A method for manufacturing a golf club shaft, the method comprising the

steps of: rolling laminar sheet material onto a mandrel to produce a first shaft segment

that is substantially cylindrical and slightly tapered throughout its length and

terminates on either end in an annular edge region, wherein a first of the annular

edge regions is adaptable to mount a golf club head;

lapping said first shaft segment in a second of the annular edge regions with

laminar sheet material to produce a second shaft segment that is substantially

frustoconical and that extends axially with the first shaft segment and to a

predetermined length therebeyond, said lapping being performed in such manner that

there is a smoothly tapering transition region along the exterior surfaces of the first

and second shaft segments, said predetermined length being formed by rolling the

sheet material onto a mandrel, said predetermined length terminating in an annular

edge region having a diameter that is substantially greater than the first annular edge

region of the first shaft segment; and

setting the sheet material of the first and second shaft segments to produce an

integral shaft of determined length.

28. The method of claim 27, further comprising the step of impregnating

the laminar sheet material with a resin that is flowable and curable by the application

of heat, wherein the setting step is performed by applying heat after the impregnating

step.

29. The method of claim 27, further comprising the step of overlapping

substantially said first and second segments with a contiguous laminar sheet material

by rolling the overlapping sheet material onto the first and second segments

approximately simultaneously.

30. A golf club comprising a shaft and a club head, wherein:

the shaft has a longitudinal axis;

the club head includes a bottom surface opposite from the shaft, the bottom surface

defining a ground plane approximately contacting the bottom surface and

extending at an angle of approximately 50-degrees from the longitudinal axis

of the shaft;

the golf club has an overall length and a center of mass;

a first distance is defined between the center of mass and the bottom surface of the

club head, measured along a line projecting perpendicularly to the ground

plane; and

the ratio of the first distance to the overall length is less than approximately 1 to 13.

31. The golf club according to claim 30, wherein the club has an overall

weight of less than approximately 400-grams, and an overall length of at least 42-

inches.

32. The golf club according to claim 30, wherein the shaft has a shaft

weight, the head has a head weight, and the ratio of the head weight to the shaft

weight is more than approximately 3 to 1.

33. A golf club comprising a shaft and a club head, wherein:

the shaft has a longitudinal axis;

the club head includes a bottom surface opposite from the shaft;

the golf club has an overall length and a center of mass;

club head, measured along the longitudinal axis of the shaft by perpendicular

projection; and

the ratio of the first distance to the overall length is less than approximately 1 to 10.

34. The golf club according to claim 33, wherein the club has an overall

eight of less than approximately 400-grams, and an overall length of at least 42-

inches.

35. The golf club according to claim 33, wherein the shaft has a shaft

weight is more than approximately 3 to 1.

97/45173 PCI7US97/09022

36. A golf club comprising a shaft and a club head attached to the shaft,

wherein the shaft has a shaft weight, the head has a head weight, and the ratio of the

head weight to the shaft weight is more than approximately 3 to 1.

37. The golf club according to claim 36, wherein the club has an overall

inches.

38. A non-grip-element-requiring elongate shaft for a golf club

comprising:

an elongate body;

a user-direct-grippable gripping end formed by said body; and

a club-head mounting end formed in said body remote from said gripping end.

39. The shaft according to claim 38, wherein said body has a mass

which, under circumstances with a head mounted on said mounting end to form an

overall assemblage, the overall assemblage has a center of mass substantially

immediately adjacent where said head is mounted on said mounting end.

40. A golf club having a shaft with a gripping end and a remote

club head mounting end receiving a club head, said club being characterized in a

region which makes up the gripping end by a mass which is solely contributed by

material which forms the gripping end.

41. A shaft for a golf club, the shaft comprising:

two overlapped elongate segments,

with a first of the two segments being slightly frustoconical about an axis and

extending from a first end of said first segment for mounting of a golf club head to a

second end of said first segment,

with a second of the two segments being slightly more frustoconical than said

first segment and extending approximately coaxially along said axis with said first

segment, with a first end of said second segment being joined with said second end

of said first segment, a second end of said second segment defining a region for

manual gripping by a user,

said first segment being approximately twice as long as said second segment,

and

said first and said second segments each being formed of one or more plies

having plural oriented fibers, the one or more plies including angularly biased fibers

in the first segment and angularly biased fibers in the second segment, with the

angularly biased fibers in the first segment being closer to axial alignment along said

axis than the angularly biased fibers in the second segment.

42. The shaft of claim 41, wherein said one or more plies include

oppositely angularly biased fiber plies having inteφosed therebetween an axially

oriented fiber ply.

43. The shaft of claim 41, wherein said one or more plies include an

axially oriented fiber ply substantially overlapping both the first and second

segments.

44. The shaft of claim 41, wherein said one or more plies are of

substantially planar flexible binder-containing sheet material.

45. The shaft of claim 41 , wherein plural fibers in the first segment

are made from material based on a group including boron, tungsten and iron, and

plural fibers in the second segment are made from material based on graphite.

46. A shaft for attachment at a first end to a golf club head, wherein the

the contour of the first portion, the first and second portions each have an axis

extending along the shaft and said first and said second portions each are formed of

one or more plies having oriented fibers, said one or more plies including angularly

biased fibers in the first portion and differently angularly biased fibers in the second

portion, with the fibers in the first portion being closer to axial alignment with the

axis of the first portion than the fibers in the second portion are to the axis of the

second portion.

47. A method for manufacturing a golf club shaft, the method comprising the

steps of: rolling plural fiber ply laminar sheet material onto a mandrel to produce a

first shaft segment that is substantially cylindrical and slightly tapered throughout its

length along a first axis and terminates on either end in an annular edge region,

wherein a first of the annular edge regions is adaptable to mount a golf club head,

and wherein the fibers in the sheet material in the first shaft segment are angularly

biased;

lapping said first shaft segment in a second of the annular edge regions with

plural fiber ply laminar sheet material to produce a second shaft segment that is

substantially frustoconical and that extends axially with the first shaft segment and to

a predetermined length therebeyond along a second axis, said lapping being

performed in such manner that there is a smoothly tapering transition region along

the exterior surfaces of the first and second shaft segments, said predetermined

length being formed by rolling the sheet material onto a mandrel, said predetermined

length terminating in an annular edge region having a diameter that is substantially

greater than the first annular edge region of the first shaft segment, and wherein the

fibers in the sheet material in the second shaft segment are angularly biased, with the

fibers in the ply in the first shaft segment being closer to axial alignment with the

first axis than the fibers in the ply in the second shaft segment are to the second axis;

and setting the sheet material of the first and second shaft segments

to produce an integral shaft of determined length.