Steel golf shaft with a composite pivot area

Abstract

A golf club shaft having an upper hollow portion with a handle end and a lower hollow portion with a head end and an intermediate flex portion therebetween. The upper portion has a lower end with a joining region extending into the flex portion. The lower portion has an upper end with a joining region extending into the flex portion. A connector in the flex portion has a central enlarged cylindrical section with a diameter extending outwardly to a diameter essentially equal to the exterior surface of the adjacent shaft portions, the connector also having an upper cylindrical section with a reduced diameter in interference contact with the interior surface at the lower end of the upper portion, the connector also having a lower cylindrical section with a reduced diameter in interference contact with the interior surface at the upper end of the lower portion of the shaft.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a steel golf shaft with a composite pivot area and more particularly pertains to tailoring the playing characteristics of golf clubs through an intermediate pivot area in the shaft.

[0003] 2. Description of the Prior Art

[0004] The use of golf shafts with variable playing characteristics of various designs and configurations is known in the prior art. More specifically, golf shafts with variable characteristics of various designs and configurations heretofore devised and utilized for the purpose of tailoring the playing characteristics of golf clubs through various methods and apparatus are known to consist basically of familiar, expected, and obvious structural configurations, notwithstanding the myriad of designs encompassed by the crowded prior art which has been developed for the fulfillment of countless objectives and requirements.

[0005] By way of example, note U.S. Pat. No. 5,439,219 to Vincent, U.S. Pat. No. 5,308,062 to Hogan and U.S. Pat. No. 5,467,984 to Veux.

[0006] While these devices fulfill their respective, particular objectives and requirements, the aforementioned patents do not describe a golf shaft with a composite or plastic pivot area that allows tailoring the playing characteristics of golf clubs through an intermediate pivot area in the shaft.

[0007] In this respect, the golf shaft with a composite pivot area according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of tailoring the playing characteristics of golf clubs through an intermediate pivot area in the shaft.

[0008] Therefore, it can be appreciated that there exists a continuing need for a new and improved golf shaft with a composite pivot area which can be used for tailoring the playing characteristics of golf clubs through an intermediate pivot area in the shaft. In this regard, the present invention substantially fulfills this need.

SUMMARY OF THE INVENTION

[0009] In view of the foregoing disadvantages inherent in the known types of golf shafts with variable playing characteristics of various designs and configurations now present in the prior art, the present invention provides an improved golf shaft with a composite pivot area. As such, the general purpose of the present invention, which will be described subsequently in greater detail, is to provide a new and improved a golf shaft with a composite pivot area and method which has all the advantages of the prior art and none of the disadvantages.

[0010] To attain this, the present invention essentially comprises a new and improved golf club comprising a shaft having a handle end with a grip thereon and a head end with a head thereon and an intermediate flex portion therebetween. One embodiment of the shaft is for a driver and would include an upper hollow steel portion about 26 inches in length constituting between about 55 and 65 percent, preferably 59.6 percent, of the length of the shaft. Also included in the shaft is a lower hollow steel portion about 12.5 inches in length constituting between about 25 and 33 percent, preferably 28.8 percent of the length of the shaft. An intermediate flex portion about 9 inches in length with about 2 inches at each end is positioned within the upper and lower portions leaving about 5 inches therebetween constituting between 9 and 14 percent, preferably 11.6 percent, of the length of the shaft. The lower end of the upper portion of the shaft remote from the handle having an exterior undercut region extending into the intermediate flex portion with the upper end of the lower portion of the shaft remote from the head having an exteriorly undercut region extending into the intermediate flex portion. A cylindrical sleeve is formed of a plurality of layers of an overwrap of a composite material having an upper and lower radial abutment in contact with the lower end of the upper portion of the shaft and the upper end of the lower portion of the shaft and having an upper end of a reduced diameter in contact with the undercut region of the lower end of the upper portion of the shaft and a lower end of a reduced diameter in contact with the undercut region of the upper end of the lower portion of shaft, and with the exterior surface of the cylindrical sleeve between the upper and lower portion of the shaft forming a smooth continuation of the shaft through the intermediate flex portion with the sleeve forming a region of greater flexibility than the portions of the shaft thereabove and therebelow for tailoring the playing characteristics of the golf clubs.

[0011] There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto.

[0012] In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.

[0013] As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for calling out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

[0014] It is therefore an object of the present invention to provide a new and improved golf shaft with a composite pivot area which has all of the advantages of the prior art golf shafts with variable playing characteristics of various designs and configurations and none of the disadvantages.

[0015] It is another object of the present invention to provide a new and improved golf shaft with a composite pivot area which may be easily and efficiently manufactured and marketed.

[0016] It is a further object of the present invention to provide a new and improved golf shaft with a composite pivot area which is of durable and reliable constructions.

[0017] An even further object of the present invention is to provide a new and improved golf shaft with a composite pivot area which is susceptible of a low cost of manufacture with regard to both materials and labor, and which accordingly is then susceptible of low prices of sale to the consuming public, thereby making such golf shaft with a composite pivot area economically available to the buying public.

[0018] Even still another object of the present invention is to provide a golf shaft with a composite pivot area for tailoring the playing characteristics of golf clubs through an intermediate pivot area in the shaft.

[0019] Lastly, it is an object of the present invention to provide a new and improved golf club shaft having an upper hollow portion with a handle end and a lower hollow portion with a head end and an intermediate flex portion therebetween. The upper portion has a lower end with a joining region extending into the flex portion. The lower portion has an upper end with a joining region extending into the flex portion. A connector is provided in the flex portion having a central enlarged cylindrical section with a diameter extending outwardly to a diameter essentially equal to the exterior surface of the adjacent shaft portions, the connector also having an upper cylindrical section with a reduced diameter in interference contact with the interior surface at the lower end of the upper portion, the connector also having a lower cylindrical section with a reduced diameter in interference contact with the interior surface at the upper end of the lower portion of the shaft.

[0020] These together with other objects of the invention, along with the various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

[0022] FIG. 1 is a perspective view of the preferred embodiment of a golf club employing a shaft with a composite pivot area constructed in accordance with the principles of the present invention.

[0023] FIGS. 1a, 1b, and 1c illustrate alternate embodiments of the invention wherein the insert is of varying lengths.

[0024] FIG. 2 is perspective showing of the shaft employed in a golf club of FIG. 1.

[0025] FIG. 3 is an enlarged showing of the intermediate flex region of the golf club shaft taken at circle 3 of FIG. 2.

[0026] FIG. 4 is a cross sectional view taken along line 4 of FIG. 3.

[0027] FIG. 5 is a side elevational view taken at line 5-5 of FIG. 4.

[0028] FIG. 6 is a cross sectional view similar to FIG. 3 but illustrating an alternate embodiment of the invention.

[0029] The same reference numerals refer to the same parts through the various Figures.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0030] With reference now to the drawings, and in particular to FIG. 1 thereof, the preferred embodiment of the new and improved golf shaft with a composite pivot area embodying the principles and concepts of the present invention and generally designated by the reference numeral 10 will be described.

[0031] The present invention, the golf shaft with a composite pivot area, is comprised of a plurality of components. Such components in their broadest context include a shaft with a metal upper portion and a metal lower portion and with a non-metallic flex portion therebetween. Such components are individually configured and correlated with respect to each other so as to attain the desired objective.

[0032] The primary component of the present invention is a shaft 12. Such shaft has a handle end 14 with a grip 16 thereon. It also has a head end 18 with a head 20 formed thereon. In addition, the shaft includes an intermediate flex portion 22 between the upper and lower ends.

[0033] In the preferred embodiment of FIG. 1, there is shown the invention including a shaft about 44 inches in length, a normal shaft length for a driver. Such shaft has an upper hollow steel portion 24 about 26 inches in length and constitutes between about 55 and 65 percent, preferably 59.6 percent, of the length of the shaft. The shaft also has a lower hollow steel portion 26 about 12.5 inches in length and constitutes between about 25 and 33 percent, preferably 28.8 percent, of the length of the shaft. The shaft also has an intermediate flex portion 22 about 9 inches in length with about 2 inches at each end within the upper and lower portions. This leaves about 5 inches therebetween constituting between 9 and 14 percent, preferably 11.6 percent, of the length of the shaft.

[0034] The lower end of the upper portion of the shaft remote from the handle has an undercut or joining region 32 which extends into the intermediate flex portion. The upper end of the lower portion of the shaft remote from the head has an undercut or joining region 34 extending into the intermediate flex portion.

[0035] A cylindrical sleeve 38 is formed of a plurality of layers of a composite material. The sleeve has an upper and lower radial abutment surface 40, 42 in contact with the lower end of the upper portion of the shaft and the upper end of the lower portion of the shaft.

[0036] The sleeve has an upper end 44 of a reduced diameter in contact with the undercut region of the lower end of the upper portion of the shaft. The sleeve also has a lower end 46 of a reduced diameter in contact with the undercut region of the upper end of the lower portion of shaft. The exterior surface of the cylindrical sleeve between the upper and lower portion of the shaft forms a smooth continuation of the shaft through the intermediate flex portion with the sleeve forming a region of greater flexibility than the portions of the shaft thereabove and therebelow. This allows for tailoring the playing characteristics of the golf clubs. It should be noted that the preferred embodiment illustrates the intermediate portion as having undercut ends for the accommodation of the adjacent portions of the upper and lower portions. It should be understood, that an inverted relationship could be utilized with the intermediate portion being tubular of a common diameter throughout its length and with the adjacent ends of the upper and lower portions being of a reduced diameter thereadjacent to fit within the hollow interior of the intermediate section.

[0037] The preferred materials for the sleeve include any conventional matrix material for the binder and with essentially inextensible strands therethrough as of graphite, carbon, glass, and other known materials for its intended purpose. The strands may be axially aligned with the shaft or at any angle, preferably up to 45 degrees to assist in varying the flex characteristics of the shaft. This arrangement forms a region of greater flex than the portions of the shaft thereabove and therebelow for tailoring the playing characteristics of the golf clubs as a function of the materials of the components, the angle of the strands, in combination with the size and positioning of the connector and sleeve with respect to the shaft portions.

[0038] In the preferred embodiment, the connector is fabricated as a composite hollow cylinder with a plurality of layers. Each layer includes aligned strands of inextensible fibers such as graphite, carbon, glass or any of the conventional materials utilized conventionally in composite materials. The strands are held in position by a flexible polymer functioning as the matrix binder material. Such matrix binder material may be of any of the conventional binder materials normally used in composite technology. The fibers in the preferred embodiment are aligned at any desired angle. They are shown in FIG. 5 as extending at about forty-five degrees from the axis of the shaft. They may be placed at any angle preferably lower down to zero degrees, at an orientation parallel with the axis of the shaft. The angular orientation will vary the flux of the connector in the one flex portion of the club.

[0039] Note is taken that the shaft above and below the connector are the stiffest portion of the shaft. The portion of the connector between the shaft is the region of greatest flex. The regions under the adjacent ends of the shaft which are undercut and provided with composite material of a lesser thickness are of an intermediate flexibility.

[0040] The current preferred embodiment of the invention for a driver shaft utilizes a composite connector between two steel tubes. The butt section of the steel is 26 inches in length. The tip portion of the steel shaft is 12.5 inches in length. The hollow composite section is 9 inches in length. Two inches at either end of the composite pieces slide into the steel portions of the shaft to which they are adhesively bonded. Thus, the total active length of the shaft is 43.5 inches. The composite tube is produced via a bladder molding operation. It has a wall thickness of about 0.040 inches and is composed of approximately 7 layers of graphite epoxy material. The fibers are oriented at angles that range from 0 degrees, along the length of the shaft, to 45 degrees. The exact fiber orientation is varied from shaft to shaft depending on the desired amount of flexibility.

[0041] In the FIG. 6 embodiment, the connector 50 is fabricated of plastic in a hollow configuration. This embodiment has a cross-section of a connector similar to that of the primary embodiment described above. Such connector provides further cost advantages over that of the primary embodiment.

[0042] FIGS. 1a, 1b, and 1c show alternate inserts where the flex portions are of varying lengths. In the FIG. 1a embodiment, the intermediate flex portion is of a length less than that of the primary embodiment; in the embodiment of FIG. 1b, the intermediate flex portion is of a length greater than that of the primary embodiment but less than half the length of the shaft.

[0043] In the embodiment of FIG. 1c, the intermediate flex portion is of a length greater than 50 percent of the length of the shaft, preferably about 65 percent of the total length of the shaft. A low cost version of the shaft would be to use a small middle section, from between about five and nine inches in length, and steel upper and lower portions. This would tend to be a fairly heavy shaft when compared to an all-composite shaft. A more expensive, and higher performance version of this shaft, would incorporate a much larger middle section composed of composite materials, preferably graphite fibers in an epoxy matrix. The composite section in this case could, as mentioned above, account for up to 65 percent of the total length of the shaft.

[0044] It should also be understood that, although the primary embodiment discloses the upper and lower portions of the shaft as being of steel tubes, other metals could be utilized. The other metals that could be utilized include metals selected from the class of metals including aluminum, titanium and other metal alloys.

[0045] The major benefit to this type of shaft would be to offer a controlled kick point in a shaft. By varying the stiffness of the composite region only, shafts of significantly different performance can be produced. The shaft should also transmit less shock and vibration to players hands when compared to traditional steel shafts, but may offer more feedback than an all graphite shaft. By utilizing steel in the tip portion and a composite mid section, it should be possible to produce a durable, low torque shaft, that still adds club head speed due to its localized flex point.

[0046] As to the manner of usage and operation of the present invention, the same should be apparent from the above description. Accordingly, no further discussion relating to the manner of usage and operation will be provided.

[0047] With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.

[0048] Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Claims

What is claimed as being new and desired to be protected by Letters Patent of the United States is as follows:

1. A new and improved golf club comprising a shaft having a handle end with a grip thereon and a head end with a head thereon and an intermediate flex portion therebetween comprising, in combination: a shaft including an upper hollow steel portion about 26 inches in length constituting between about 55 and 65 percent, preferably 59.6 percent, of the length of the shaft and a lower hollow steel portion about 12.5 inches in length constituting between about 25 and 33 percent, preferably 28.8 percent of the length of the shaft with an intermediate flex portion about 9 inches in length with about 2 inches at each end within the upper and lower portions leaving about 5 inches therebetween constituting between 9 and 14 percent, preferably 11.6 percent, of the length of the shaft, the lower end of the upper portion of shaft remote from the handle having an undercut region extending into the intermediate flex portion with the upper end of the lower portion of the shaft remote from the head having an undercut region extending into the intermediate flex portion; and a cylindrical sleeve formed of a plurality of layers of a composite material having an upper and lower radial abutment surface in contact with the lower end of the upper portion of the shaft and the upper end of the lower portion of the shaft and having an upper end of a reduced diameter in contact with the undercut region of the lower end of the upper portion of the shaft and a lower end of a reduced diameter in contact with the undercut region of the upper end of the lower portion of shaft, and with the exterior surface of the cylindrical sleeve between the upper and lower portion of the shaft forming a smooth continuation of the shaft through the intermediate flex portion with the sleeve forming a region of greater flexibility than the portions of the shaft thereabove and therebelow for tailoring the playing characteristics of the golf clubs.

2. A golf club shaft having an upper hollow portion with a handle end and a lower hollow portion with a head end and an intermediate flex portion therebetween comprising: the upper portion having a lower end with a joining region extending into the flex portion, the lower portion having an upper end with a joining region extending into the flex portion; and a connector in the flex portion having a central enlarged cylindrical section with a diameter extending outwardly to a diameter essentially equal to the exterior surface of the adjacent shaft portions, the connector also having an upper cylindrical section in interference contact with the lower end of the upper portion, the connector also having a lower cylindrical section in interference contact with the upper end of the lower portion of the shaft.

3. The shaft as set forth in claim 2 wherein the upper and lower portions of the shaft are fabricated of steel.

4. The shaft as set forth in claim 2 wherein the upper portion of the shaft constitutes between about 55 and 65 percent of the length of the shaft.

5. The shaft as set forth in claim 2 wherein the intermediate flex portion constitutes between about 9 and 14 percent of the length of the shaft.

6. The shaft as set forth in claim 2 wherein the intermediate flex portion constitutes up to about 65 percent of the total shaft length.

7. The shaft as set forth in claim 2 wherein the lower portion of the shaft constitutes between about 9 and 14 percent of the length of the shaft.

8. The shaft as set forth in claim 2 wherein the connector is formed of a non-metallic material.

9. The shaft as set forth in claim 2 wherein the connector is formed of a composite material with inextensible strands from between about 0 degrees and 45 degrees with respect to the axis of the shaft.

10. The shaft as set forth in claim 2 wherein the connector is formed of plastic.

11. The shaft as set forth in claim 2 wherein the upper end and lower end are selected from the class of metals including aluminum, titanium and other metal alloys.