Golf Club With Unit-cell Head Construction

Abstract

A golf club having a head wherein there is disposed a relatively strong but lightweight unit-cell structure portion between the head's toe and heel portions and immediately behind its generally planar impact face so that the weight of the head is concentrated at the toe, the toe and heel, or the toe, heel and sole portions in order to provide a relatively stiff and wider effective hitting area along with a relatively lower center of gravity, the unit-cell structure in an iron configuration, for example, including a plurality of parallel tubular elements extending generally perpendicular to the plane of the impact face. BACKGROUND OF THE INVENTION The background of the invention will be set forth in two parts. 1. Field of the Invention The present invention pertains generally to the field of sporting equipment, and more particularly to golf clubs, both woods and irons. 2. Description of the Prior Art Over the years there have been developed literally hundreds of schemes striving to provide golf clubs having better distance and accuracy characteristics. Some of these schemes dealt with the use of metallic inserts in a club head's golf ball striking surface, while others stressed the use of inserts having what were considered materials with better resilience than metals, under compressive stresses. Another technique has been to hollow out the head of a club and provide a plurality of relatively small openings in the striking face and one or more larger openings in the head, all communicating with the head cavity so as to reduce air resistance and thereby overcome air drag which may tend to throw the club out of its desired path of travel. In a more recent line of effort, techniques have been proposed which are designed to broaden the "sweet spot" of a golf club head, which is widely known as the area on a club face which should come into contact with a golf ball in order to give the greatest and straightest flight to the ball and the best handling feeling. In conventional configurations, the weight of the club head is concentrated just behind the sweet spot in order to provide the above-mentioned desired characteristics. With the weight so concentrated, the sweet spot tends to be relatively small. This made it rather difficult for most golfers to consistently cause the sweet spot to come into contact with the ball. Missing the sweet spot usually causes the ball to travel a considerably lesser distance and often contributes to the tendency to "hook" or "slice" the ball. The techniques to broaden the sweet spot generally provide a means to concentrate the weight of the club head in the heel and the toe rather than directly behind the sweet spot. In one particular design, the head is fabricated of a relatively light material and inserts of denser material are provided in the area of the heel and toe of the club head. In another design, the portion of the club head directly behind the club's ball-striking face is removed so that the weight is necessarily located in other portions of the head, namely the toe and heel portions. In both of these designs the sweet spot is indeed broadened, however, the striking face of each of these clubs would lack the stiffness needed to advantageously utilize the elastic energy generated in the golf ball if it is not made thick enough. This stiffness is needed in order to preclude any deformation of the face, under impact, that would tend to increase the area of contact between the face of the ball and thus dissipate energy in the club head instead of imparting it to the ball. SUMMARY OF THE INVENTION In view of the foregoing factors and conditions characteristic of the prior art, it is a primary object of the present invention to provide a new and improved golf club that has a broadened sweet spot and a relatively stiff ball striking face. It is another object of the present invention to provide a golf club that includes means for concentrating the weight of the head in the toe, the toe and heel, or the toe, heel and sole regions and not behind the central portion of the club's ball striking face. It is still another object of the present invention to provide an economical-to-fabricate golf club that includes a unit-cell portion immediately behind its striking face, which cell portion enhances the stiffness of the face while allowing the weight of the head to be concentrated in more advantageous locations. It is yet another object of the present invention to provide a golf club in the form of an iron which incorporates a unit-cell structure immediately behind the striking face. It is yet a further object of the present invention to provide a wood or driver having a unit-cell structure immediately behind the club's striking face. According to the present invention, a golf club is provided which includes an elongated shaft having a lower end and also a head having a hosel in an upper portion thereof wherein the lower end of the shaft is fixedly disposed. The head also includes a toe portion and a heel portion and a generally planar impact face between these portions and hollow unit-cell structure means disposed immediately behind the impact face for broadening the effective hitting area of the impact face while reinforcing and enhancing its stiffness. The club may be in the form of either an iron or a wood and the unit-cell structure means may take the form of a honeycomb construction or simply a plurality of unit cells, of any desired shape, bored or cast or otherwise provided in the head directly behind the impact face of the club.

Description

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be understood by making reference to the following description taken in conjunction with the accompanying drawing in which like reference characters refer to like elements in the several views.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of an embodiment of the invention in the form of an iron incorporating a unit-cell structure in accordance with the present invention;

FIG. 2 is a sectional representation of the iron of FIG. 1;

FIG. 3 is an elevational view of the embodiment of the invention in the form of a wood or driver;

FIG. 4 is a sectional view of the driver of FIG. 3, taken along line 4-4;

FIG. 4A is a partial sectional view illustrating another embodiment of the invention shown in FIG. 3;

FIG. 5 is a bottom plan view of the club of FIG. 3; and

FIGS. 6-10 illustrate exemplary configurations of unit-cell constructions incorporated in golf club heads in accordance with the present invention.

DESCRIPTION OF THE INVENTION

Referring now to the drawing and more particularly to FIGS. 1 and 2, there is shown a golf club in the form of an iron 11 having a shaft 13 (shown broken away) with a lower end 15 fixedly mounted in a hosel portion 17 of a head 19. The head 19 includes a toe portion 21 and a heel portion 23 and a generally planar ball striking or impact face 25 located between the toe and heel portions. Also, a unit-cell structure 27 is disposed immediately behind and is an integral part of a rear surface 29 of the impact face 25.

In this embodiment, the unit-cell structure 27 is in the form of a honeycomb core having a hexagonal cross-sectional pattern, the opposite side walls 31 of which lie in parallel planes in a direction generally perpendicular to the impact face 25. As shown in FIG. 2, for example, the structure 27 of the head 19 is located in a rear cavity portion 33 which also extends generally between the toe and heel portions 21 and 23, respectively, and above a sole portion 35. The honeycomb structure 27 acts as a very strong but lightweight backup support or reinforcement for the relatively thin impact face 25 so that the latter will not deform under impact loads caused by the face striking a golf ball.

As noted above, the structure 27 is located in a rear cavity of the head. This configuration allows the weight of the head to be concentrated mostly in the toe or toe and heel, or the toe, heel and sole portions of the head instead of behind the striking surface in order to provide a considerably greater sweet spot area without sacrificing stiffness in the face 25.

The unit-cell construction thus allows the material of the club behind the striking face to be thinner (without giving up the desired stiffness) than prior art head constructions wherein material behind the striking face was removed in order to broaden the effective striking area. For example, the striking face of an iron constructed in accordance with the present invention may be as thin as 0.030 inch, thus allowing the material normally required to provide the necessary face stiffness to be more advantageously located elsewhere.

The unit-cell construction may be analogized in many respects to a T-beam construction arrangement wherein the interconnected side walls 31 of the unit-cell structure 27 act as a T-beam web construction to reinforce the flange (striking face) portion.

The novel and extremely advantageous unit-cell construction of the present invention may be provided by any conventional process such as casting it as an integral part of the head, machining it into a forged or cast head, or brazing a honeycomb core into the cavity 35 provided in a forged or cast head.

It can thus be seen that the unique construction of the golf club iron 11 affords the stiffness that is required in the hitting face of an iron cast head with only a small fraction of the weight that would be in the same central area in a conventional forged head. It should be evident therefore that in the unit-cell iron head construction 11, the weight distribution is such that a wider sweet spot is provided along with better balance and a desirable lower center of gravity.

Unit-cell constructions may also be used effectively in woods. Woods are conventionally made from laminated wood structures or from composites of wood and plastics. Both wood and plastic materials have very little moduli of elasticity as compared to metals and are also much lighter than metals, which is the primary reason that these materials are employed in all conventional designs. However, unit-cell constructions in accordance with the present invention may be employed behind a high modulus (high unit weight) ball hitting surface in a wood because the higher weight at the face can be tolerated since a large portion of the weight normally located behind the ball striking surface is not present. As in the case of irons, the weight saved behind the ball hitting surface may be used to improve the club by concentrating the weight of the club at the toe portion, the toe and heel portions, or at the toe, heel and sole portion of the club.

FIGS. 3-5 illustrate such an embodiment of the present invention. Here, a wood or driver 51 is shown to include a shaft 53 attached to a hosel portion 55 of a wood or wood/plastic head 57. The head 57 also includes what are generally defined as a toe portion 59, a heel portion 61, a sole portion 63 and a high modulus, rigid ball striking or hitting face 65. Within the head 57 is disposed a unit-cell configuration 69 having a plurality of elongated hollow cells, the longitudinal axis of which are parallel and, in this embodiment, are generally at a relatively small angle with respect to a normal to the face 65.

The unit-cell configuration 69 may consist of a plurality of parallel bores of any desired cross-sectional shape (as, for example, shown in FIGS. 7 and 10) in the wood or wood/plastic head 57. The hollow bores extend rearwardly immediately behind a metal plate 71 of high modulus material, for example, and terminate in a plane defining an end wall 73, the metal plate 71, the end wall 73 and the hollow bore configuration therebetween generally defining a sandwich honeycomb structure.

Also in accordance with the present invention, the unit-cell configuration 69 may comprise a prefabricated honeycomb core 75 having relatively thin walls 77 of any suitable lightweight but strong material such as brass or aluminum or certain plastics, for example. The core 75 is disposed in a cavity 79 formed or milled in the head 57, the longitudinal axis of the core 75, like the previously mentioned bores, generally being at a relatively small angle with respect to a normal to the face 65. Again, the metal plate 71 and the rear walls 73 of the cavity 79 constitute planar facings bonded to the ends of the honeycomb core 75 to define an extremely strong lightweight hollow honeycomb sandwich configuration.

The face plate 71 may also be a hard plastic material that is disposed by any conventional technique in the forward end of the honeycomb core 75' to a depth limited by a thin barrier wall 81, as illustrated in the fragmentary view of FIG. 4A, for example. In this embodiment, as in the one shown in FIG. 4, the core does not extend to the face 65, although in the last referred to embodiment it may virtually do so depending on design requirements and desires. Where the plastic material is transparent, the cross-sectional configuration, which may be of any desired shape or arrangement such as any of those shown in FIGS. 6-10, will be visible through the face 65.

With a considerable portion of the relatively heavy material normally located behind the face plate of the wood club being removed and substituted therefor by the lightweight but strong sandwich honeycomb structure, the weight so displaced may be advantageously located in more desirable locations such as, for example, in a relatively heavy metal sole plate 83 attached by conventional flat head screws 85 to the head's sole portion 63.

Like the T-beam analogy of the unit-cell structure for irons, the unit-cell structure utilized in accordance with the present invention as to woods may be considered analogous or at least best compared to I-beams. The unit-cell structure in the wood embodiments is similar to a honeycomb sandwich with its characteristics of high strength-to-weight ratio; resistance to vibration; use of nearly any structural material; and ease of fabrication. The honeycomb structure is basically composed of a core sandwiched between a pair of facings. The latter correspond to I-beam flanges where the high density, high strength material is placed as far from the neutral axis as possible to thus increase the section modulus. The core may be compared to the web of an I-beam which supports the flanges and allows them to act as a unit. The honeycomb, like the web, carries the shear stresses, except that it maintains continuous support for the facings, allowing the facings to be worked up to or above their yield strength without crimping or buckling. To obtain these advantages, of course, the honeycomb core must be bonded to the facings so that the latter will be capable of transmitting shear loads between the two components to thus make the entire structure an integral unit. In this regard, any conventional bonding technique suitable for the materials encountered may be utilized.

As the sandwich structure is loaded as a beam, the multi-unit cell core and the bond resist shear loads while the facings resist the moments due to bending forces, and thus carry the tensile or compressive load. When the structure is loaded as a column, only the facings act to resist the column forces and the core stabilizes the facings to prevent buckling.

Actually, honeycomb sandwich structures are more efficient than I-beams in that the combination of high density facings and low density cores provide a much higher section modulus per unit density than any other known construction method.

Theoretically, any thin, bondable material with high tensile or compressive strength-to-weight ratio is a potential facing material for honeycomb sandwich structures. Of course, the loads, their orientations and the overall configuration of the structure will determine the type of stresses that must be resisted, e.g., compression, tension, shear, etc.

It has been found that the same formulas used to calculate stresses in I-beams may be used to determine the stresses developed in honeycomb sandwich structures, however, special considerations must be applied where high concentrated imact loads, such as encountered in a golf club head, are encountered. Thus, although a very thin facing material will generally satisfy all tensile and compressive requirements, a thicker facing is required to resist impact, in that it is capable of better distributing the impact load over a wider area to thus reduce the stresses on the core. However, even this thicker facing, in the case of a metal plate, may be much thinner and lighter than conventional golf balls face plates for the same stiffness.

As evident from the figures, especially FIGS. 1 and 3, the boundary cell walls 31 and 77 respectively, have a cross sectional thickness substantially less than the average of the largest and smallest cross sectional dimension of the bounded unit cell.

It should therefore be evident from the foregoing that there has herein been described novel and highly useful golf club constructions that broaden a club's sweet spot without weakening its ball striking surface while allowing the weight of the head to be located in the most advantageous location.

It should also be understood that the material used in construction of the various embodiments of the invention is not critical and that any material having the desired strength, weight and modulus characteristics may be substituted for those materials specifically names. Accordingly, it should be clear that the invention is susceptible to variations and embodiments, beyond those herein disclosed in detail, well within the scope of competence by those skilled in the art.

Claims

What is claimed is:

1. A golf club, comprising:

an elongated shaft having a lower end; and

a head having a hosel in an upper portion thereof, said lower end of said shaft being fixedly disposed in said hosel, said head also having a toe portion and a heel portion and a generally planar high modulus impact face between said toe and heel portions, said head portion having hollow unit-cell structure means disposed therein immediately behind said impact face for broadening the effective hitting area of said impact face while reinforcing and enhancing the stiffness of said impact face, said unit-cell structure means including a plurality of interconnected elongated unit-cells encapsulated by other interconnected elongated unit-cells, each of the unit-cells being defined by boundary cell walls, each boundary cell wall having a cross sectional thickness substantially less than the average of the largest and smallest external cross sectional dimension of the bounded unit cell, said boundary cell walls extending generally rearwardly from and generally perpendicularly to the plane of said impact face.

2. The golf club according to claim 1, wherein said unit-cell structure means is disposed in a hollowed out cavity portion of said head.

3. The golf club according to claim 1, wherein said club is an iron and said unit-cell structure means is disposed in a rearward exposed cavity section, said means extending from a rear surface situated immediately behind said impact face, said impact face and said rear surface defining a relatively thin impact wall therebetween.

4. The golf club according to claim 3, wherein said boundary cell walls define a honeycomb core structure.

5. The golf club according to claim 4, wherein said boundary cell walls of said honeycomb core structure have a hexagonal cross section.

6. The golf club according to claim 4, wherein said boundary cell walls of said honeycomb core structure have a rectangular cross section.

7. The golf club according to claim 4, wherein said boundary cell walls of said honeycomb core structure have a triangular cross section.

8. The golf club according to claim 4, wherein said boundary cell walls of said honeycomb core structure have a circular cross section.

9. The golf club according to claim 1, wherein said club is a wood and the unit-cells define a plurality of elongated hollow bores in said head extending rearwardly from a forwardly disposed impact plate, said impact face being the outer surface of said impact plate.

10. The golf club according to claim 9, wherein said bores terminate at their rearward end in a common plane defining a rearward wall of said unit-cell structure means, and wherein said impact plate, said rearward wall and the bore configuration in said head define a sandwich honeycomb structure.

11. The golf club according to claim 9, wherein said hollow bores have a generally circular cross section.

12. The golf club according to claim 9, wherein said hollow bores have a generally ellipsoid cross section.

13. The golf club according to claim 9, wherein said bores have differing cross sectional dimensions.

14. The golf club according to claim 1, wherein said club is a wood and said head includes a cavity therein, said unit-cell structure means being at least partially disposed therein.

15. The golf club according to claim 14, wherein said unit-cell structure means includes a face plate and wherein the unit-cells of said unit-cell structure means define a prefabricated honeycomb core structure disposed in said cavity the rearward end of which being bonded to the rearward wall of said cavity and the forward end of which being bonded to the inner wall of said face plate to define a sandwich honeycomb structure.

16. The golf club according to claim 15, wherein said boundary cell walls of the unit-cells define in cross section a curved geometric pattern.

17. The club according to claim 15, wherein said boundary cell walls of the unit-cells define in cross section a multiple straight sided geometric pattern.

18. The golf club according to claim 14, wherein the unit-cells of said unit cell structure means define a prefabricated honeycomb core structure disposed in said cavity the rearward end of which being bonded to the rear wall of said cavity and the forward end of said core structure being spaced from and behind said impact face, said core structure including a barrier wall disposed transversely to the longitudinal axis of said core structure and spaced a relatively short distance behind said forward end of said core structure, said impact face being of a relatively hard plastic material that extends into said core structure only to said barrier wall.