GOLF CLUB HEAD COMPRISING A STRIKE FACE WITH A HARDNESS SUITABLE FOR THE HARDNESS OF A GOLF BALL

Abstract

A golf club head comprising a substantially flat strike face configured to strike a golf ball. The head has a body having a front face, at least one cavity opening on the front face, at least one ballast made of a second dense material, positioned in the at least one cavity and secured to the body, a front layer that has a first face forming the strike face and a second face opposite the first face, the second face of the front layer being in contact with the body and secured thereto, at least over the entire periphery of the front face, the front layer being made of a first material that has a Shore A hardness of less than 35.

Description

FIELD OF THE INVENTION

The present application relates to a head for a golf club of the putter type, comprising a striking face with a hardness adapted to the hardness of a golf ball in order to limit the occurrence of vibrational phenomena.

BACKGROUND OF THE INVENTION

A putter is a golf club used to make a golf ball roll on a green so as to make it enter a hole. It comprises a shaft, which at a first end has a handle for gripping it and at a second end has a head for striking a golf ball.

This head comprises an approximately planar striking face for striking a golf ball and a volume with a center of gravity which is set depending on the desired features.

According to one embodiment, the head of the putter is metallic and has a hardness very much greater than that of the golf ball. This difference in hardness leads to the occurrence of vibrational phenomena, this being detrimental to the accuracy of the shot.

US3.211.44 describes a golf club of the putter type which has a metallic body and a striking face made of rubber with a Shore A hardness of between 65 and 85. This solution does not make it possible to optimally reduce vibrations.

US2004/0242342 describes a golf club head which comprises a shell and various layers positioned in the shell, including a front layer forming the striking face and at least one intermediate damping layer between the striking layer and the shell. According to one embodiment, the front layer is metallic or made of a composite material and has a Shore A hardness greater than or equal to 90. As above, this solution does not make it possible to optimally reduce vibrations.

US8.900.071 also describes a golf club head which comprises a shell and an insert positioned in the shell. This insert comprises three layers, including a front layer forming the striking face, an intermediate layer and a rear layer. According to this document, the front layer has a hardness h1 and a modulus of elasticity r1, the intermediate layer has a hardness h2 and a modulus of elasticity r2, and the rear layer has a hardness h3 and a modulus of elasticity r3, with the hardnesses and the moduli of elasticity being chosen such that h1>h2, h3>h2, r1>r2 and r3>r2.

According to one embodiment, the front layer has a Shore D hardness of between 35 and 65, that is to say equivalent to a Shore A hardness of greater than 80. As above, this solution does not make it possible to optimally reduce vibrations.

U.S. Pat. No. 5,458,332 describes a golf club head having a striking face provided with an insert made of polyurethane with a hardness of between 25 Shore A and 80 Shore D.

US2008096682 describes a golf club head having a striking face provided with an insert with a hardness of between 20 and 100 Shore A.

US2002016219 describes a golf club head having a striking face provided with an insert with a hardness of 15 Shore A.

None of these embodiments make it possible to obtain a balanced golf club head with optimum damping of vibrations.

The present invention seeks to overcome all or some of the drawbacks of the prior art.

SUMMARY OF THE INVENTION

To that end, the invention relates to a golf club head comprising a substantially planar striking face configured to strike a golf ball, characterized in that the head comprises:

• • a body having a front face and at least one cavity opening into the front face,
  • at least one ballast weight which is made of a dense second material, is positioned in at least one cavity and is secured to the body,
  • a front layer, which has a first face forming the striking face and a second face opposite the first face, the second face of the front layer being in contact with the body and secured to the latter, at least over the entire periphery of the front face, said front layer being made from a first material which has a Shore A hardness less than 35.

Since the material of the striking surface and that of the golf ball have similar hardnesses, the occurrence of vibrational phenomena is limited. In addition, the presence of cavities and ballast weights makes it possible to obtain a balanced head.

According to other features taken individually or in combination:

• • the first material is wood with a Janka hardness greater than or equal to 1500 lbf and less than 4000 lbf;
  • the front layer has a thickness of between 3 and 8 mm;
  • at least one ballast weight is spaced apart from the front layer to obtain an intermediate zone delimited by the ballast weight, the front layer and the body;
  • the intermediate zone is completely filled with at least one third material chosen to dampen noise;
  • the first, second and third materials are chosen such that the first material has a hardness less than the hardness of the third material, which is itself less than the hardness of the second material;
  • the body comprises multiple cavities distributed on either side of a fastening system configured to connect the head to a shaft;
  • since the fastening system is off-center, the body comprises a cavity on a first side of the fastening system and multiple cavities on a second side of the fastening system;
  • the body comprises multiple cavities all having the same cross section in a plane parallel to the front face;
  • the body comprises a filler material interposed between the ballast weight and the cavity, the filler material having a low density which is considerably less than that of the ballast weight.

Another subject of the invention is a golf club of the putter type comprising a head according to one of the above features.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages will become apparent from the following description of the invention, which description is given solely by way of example, with reference to the appended drawings in which:

FIG. 1 is a perspective view of a golf club of the putter type, illustrating one embodiment of the invention,

FIG. 2 is a perspective view from a first viewing angle of a golf club head, illustrating one embodiment of the invention,

FIG. 3 is a perspective view from a second viewing angle of the golf club head which is visible in FIG. 2,

FIG. 4 is a perspective view illustrating the various parts of the golf club head which is visible in FIG. 2,

FIG. 5 is a perspective view of a shell of a golf club head, illustrating one embodiment of the invention,

FIG. 6 is a top view of the shell which is visible in FIG. 5,

FIG. 7 is a schematic representation of a golf club head, illustrating one embodiment of the invention,

FIG. 8 is a perspective view of part of a golf club shaft, illustrating one embodiment of the invention,

FIG. 9 is a cross section through the golf club shaft which is visible in FIG. 8,

FIG. 10 is a perspective view of a golf club head, illustrating another embodiment of the invention,

FIG. 11 is a section, along the plane P11, of the golf club head which is visible in FIG. 10,

FIG. 12 is a perspective view of the body of the golf club head which is visible in FIG. 10,

FIG. 13 is a perspective view of a core of a curved junction portion of a golf club shaft, illustrating one embodiment of the invention,

FIG. 14 is a perspective view of a sleeve of reinforcing fibers, illustrating one embodiment of the invention, and

FIG. 15 is a cross section through a core of a curved junction portion of a golf club shaft, illustrating one embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to an embodiment which is visible in FIG. 1, a golf club 10 of the putter type comprises a shaft 12, a handle 14 at a first end 12.1 of the shaft 12, and a head 16 which is connected to a second end 12.2 of the shaft 12 and is configured to strike a golf ball 18.

According to one manufacturing method, the golf ball 18 comprises a solid core covered with multiple layers, of which the last layer is made of Surlyn™ or balata, for example. The golf ball 18 has a low surface hardness.

The shaft 12 may be metallic, made of composite material or made of any other material. Apart from its ends, the shaft 12 has a cylindrical shape and has an axis of revolution A12. In a variant, the shaft 12 may be cylindrical at its two ends and slightly conical between them. This shaft 12 is rectilinear. It may comprise a curved junction portion 19, referred to as “hosel”, at its second end 12.2.

According to one configuration, the shaft 12 comprises two separate parts: the junction portion 19 and the rest of the shaft 12. According to one configuration, the junction portion 19 and the rest of the shaft 12 are connected by a dismountable connection system, like a ferrule.

The head 16 comprises a substantially planar striking face 20 and a fastening system 22 for fastening the shaft 12. According to one configuration, the fastening system 22 comprises a blind hole in which the second end 12.2 of the shaft 12 is fitted. Other solutions could be envisaged for connecting the shaft 12 and the head 16.

The handle 14, the shaft 12 and the fastening system 22 are not described in more detail because they are known to those skilled in the art.

For the remainder of the description, a longitudinal direction DL is substantially perpendicular to the striking face 20. A transverse plane is perpendicular to the longitudinal direction DL.

According to one embodiment, which is visible in FIGS. 2, 3, 10 and 11, the head 16 comprises a body 24 and a front layer 26, which has a first face 26.1 forming the striking face 20 and a second face 26.2 which is opposite the first face 26.1 and is oriented toward the body 24. As a result, the front layer 26 is pressed against the body 24 in a joining plane 28 (visible in FIGS. 7 and 11). According to one configuration, this front layer 26 has a substantially constant thickness and has a substantially constant cross section equal to that of the body 24 in the joining plane 28.

According to one embodiment, the front layer 26 is made from a first material which has a hardness lower than that of the golf ball 18 plus 20%. Since the front layer 26 and the golf ball 18 have similar hardnesses, the occurrence of vibrational phenomena is limited.

The first material should have a hardness greater than that of the golf ball 18 in order to ensure an optimum transfer of energy between the head 16 and the golf ball 18 when it is struck. This hardness greater than that of the golf ball 18 also makes it possible to avoid premature wear of the striking face 20. The front layer 26 thus has a Shore A hardness greater than or equal to that of the golf ball 18 plus 5%.

This front layer 26 has a thickness (distance separating the first and second faces 26.1, 26.2) of between 3 and 8 mm.

In a variant, all or virtually all of the head 16 is made from a first material which has a hardness lower than that of the golf ball 18 plus 20%. The first material has a hardness greater than that of the golf ball 18.

Irrespective of the embodiment, the head 16 is made, at least partially over a certain thickness starting from the striking face 20, of a first material which has a Shore A hardness less than 35 or less than that of the golf ball 18 plus 20%. The first material has a hardness greater than that of the golf ball 18.

According to one embodiment, the first material is wood with a Janka hardness greater than or equal to 1500 lbf. The hardest woods have a Janka hardness less than 4000 lbf, equivalent to less than a Shore A hardness of 35.

By way of example, the wood chosen is ebony. Of course, the invention is not limited to this core concept. In addition, the invention is not limited to wood. Thus, other materials having hardnesses within the range indicated above may be suitable. However, wood contributes to reducing the vibrational phenomena.

According to one embodiment, the body 24 may be made of a single material or comprise a combination of materials, as illustrated in FIGS. 4 and 7. The body 24 may comprise a single element or multiple assembled elements.

According to one configuration, the body 24 is made from wood and comprises at least one insert serving as ballast weight.

According to other configurations, which are visible in FIGS. 4 and 7, the body 24 comprises a shell 30 which has a front face 30F against which the second face 26.2 of the front layer 26 is pressed, and at least one cavity 32 opening into the front face 30F. This shell 30 may be made of wood, of composite material or of any other material.

For each cavity 32, the body 24 comprises at least one ballast weight 34 positioned in the cavity 32. This ballast weight 34 is made of a dense second material, such as lead, tungsten or others.

Each ballast weight 34 is secured to the shell 30 by adhesive bonding or any other similar technique. According to one embodiment, which is visible in FIG. 11, a filler material 35, having a low density which is considerably less than that of the ballast weight, is interposed between the cavity 32 and the ballast weight 34, the filler material 35 providing the join between the bottom of the cavity 32 and the ballast weight 34. By way of example, the filler material 35 is a resin.

According to another feature, the front layer 26 is in contact with the shell 30 and is secured to the latter, at least over its entire periphery, by adhesive bonding or any other similar technique.

As a result, the force and inertia acquired by the shell 30 and the ballast weight 34 when the golf club is moving are transferred via peripheral surface contact to the front layer 26 upon impact with the golf ball 18 and, in so doing, are directly transmitted to the latter.

Taking account of the hardness of the front layer 26 or of the head 16, the collision with the golf ball 18 is fully absorbed, thereby limiting the occurrence of vibrational phenomena.

According to one embodiment, at least one ballast weight 34 is spaced apart from the front layer 26. As a result, the head 16 comprises an intermediate zone 36 delimited by the ballast weight 34, the front layer 26 and the shell 30. This intermediate zone 36 may be empty or completely filled with at least one third material chosen to dampen noise. By way of example, the third material is balsa or a foam made of plastics material.

This intermediate zone 36 is positioned in the body 24, in a recess provided in the second face 26.2 of the front layer 26 or on either side of the joining plane 28.

According to another particular feature, the first material of the front layer 26 has a hardness h26, the second material of the ballast weight 34 has a second hardness h34, the third material of the intermediate zone 36 has a third hardness h36; the first, second and third materials being chosen such that the first hardness h26 is less than the third hardness h36, which is itself less than the second hardness h34.

The number, the dimensions, the shapes and the arrangement of the cavities and the shapes and dimensions of the body are determined depending on the features desired for the head 16.

According to another particular feature, which is visible in FIG. 11, the body 24 comprises multiple cavities 32 distributed on either side of the fastening system 22.

According to one configuration, since the fastening system 22 is off-center, the body 24 comprises a cavity on a first side of the fastening system and multiple cavities, notably four cavities, on a second side of the fastening system 22. This distribution of the cavities 32 combined with the fact that a filler material 35 may be interposed between the ballast weight 34 and the bottom of each cavity 32 makes it possible to optimize the distribution of the masses and to balance the head 16, which can be adapted to each golfer. Each cavity 32 has a depth (dimension measured parallel to the direction DL) greater than or equal to 5 mm.

According to one configuration, the cavities 32 have the same cross section in a plane parallel to the front face F30. This solution makes it possible to simplify the manufacture and management of the ballast weights 34. The cavities thus have a cylindrical shape and have the same diameter.

It goes without saying that the invention is not limited to this number of cavities and to this arrangement of the cavities.

Irrespective of the embodiment, the body 24 comprises at least one cavity 32 which leads into its front face 30F, against which the front layer 26 is pressed. The latter is thus connected by adhesive bonding to the body 24 all around the cavities 32, at least over the peripheral zone of the front face 30F. This configuration contributes to reducing the vibrational phenomena.

The golf club 10 comprises at least one indicator promoting the positioning and/or orientation of the striking face 20 with respect to the golf ball 18 and/or to the desired trajectory of the golf ball 18. By way of example, the head 16 comprises a reference 38 making it easier to align the impact zone with the golf ball.

According to one embodiment, which is visible in FIGS. 8 and 9, the shaft 12 comprises a visual reference 40 making it easier to orient the striking face 20. This visual reference 40 provides a visual contrast with the rest of the shaft 12.

According to a particular feature, the visual reference 40 is a strip of material with a thickness e protruding from the surface of the shaft 12 and extends between a rectilinear first lateral edge 40.1 and a rectilinear second lateral edge 40.2, the first and second lateral edges 40.1, 40.2 being parallel to one another and parallel to the axis of revolution A12 of the shaft 12.

The shaft 12 has a median alignment plane PMA which must be correctly oriented in order that the striking face 20 is correctly oriented in relation to the desired trajectory of the golf ball 18. The first and second edges 40.1, 40.2 are positioned in relation to the median alignment plane PMA such that the visual reference 40 is not visible by or located in a field of view 44 of a golfer when they are preparing a shot and positioning the striking face 20 close to the ball 18, or such that a zone 42 of the shaft 12 that is not covered by the visual reference 40 and is located at the same height as the latter is not visible by or located in the field of view 44 of the golfer when they are preparing a shot and positioning the striking face 20 close to the ball 18. Taking account of the thickness e of the visual reference 40, the first and second lateral edges 40.1, 40.2 are spaced apart from the median alignment plane PMA. As a result, the straight line passing through the first lateral edge 40.1 and the center O of the shaft 12 forms, with the median alignment plane PMA, an angle α identical to that formed between the median alignment plane PMA and the straight line passing through the second lateral edge 40.2 and the center O of the shaft 12. This angle α is between 1° and 27°, preferably between 10° and 27°, for a visual reference 40 having a thickness of about several tenths of a millimeter to 0.5 mm. This angle will vary essentially depending on the thickness e of the strip of material and on the length of the shaft 12. As a result, the angle α is substantially equal to 11∪ for a visual reference 40 having a thickness e of about several tenths of a millimeter. It is substantially equal to 26° for a visual reference 40 having a thickness e of about 0.5 mm.

According to a first configuration, the distance between each of the first and second lateral edges 40.1, 40.2 and the median alignment plane PMA depends on the thickness e of the visual reference 40 and is set such that there is only a single angular orientation of the shaft 12 about its axis of revolution A12 for which the visual reference 40 is no longer in the field of view 44 of the golfer preparing a shot.

As long as part of the visual reference 40 is in the field of view 44 of the golfer, the shaft 12 is not correctly oriented. Once it is no longer visible, the shaft 12 and the striking face 20 are correctly oriented.

According to a second configuration, the distance between each of the first and second lateral edges 40.1, 40.2 and the median alignment plane PMA is set such that there is only a single angular orientation of the shaft 12 about its axis of revolution A12 for which that zone 42 of the shaft 12 that is not covered by the visual reference 40 and is located at the same height as the latter is no longer in the field of view 44 of the golfer preparing a shot.

As long as part of that zone 42 of the shaft 12 that is not covered by the visual reference 40 is in the field of view 44 of the golfer, the shaft 12 is not correctly oriented. Once that zone 42 of the shaft 12 that is not covered by the visual reference 40 is no longer visible, the shaft 12 and the striking face 20 are correctly oriented.

The junction zone is generally not rectilinear. It comprises at least two rectilinear end portions connected by at least one curved portion. According to one configuration, the junction zone 19 comprises two end portions, an intermediate portion and curved portions connecting the various portions. The junction zone 19 has a geometry adapted to each golfer depending notably on their morphology and the characteristics of their game. There are methods for determining the geometry of this junction zone 19.

A method for manufacturing a junction zone 19 comprises a step of determining a virtual shape of the junction zone 19, a step of manufacturing a core 46 (visible in FIG. 13) using an additive manufacturing technique on the basis of the virtual shape of the junction zone 19, a step of positioning at least one flexible ply 48 of reinforcing fibers (visible in FIG. 14) around the core 46, and a step of hardening the flexible sleeve 48 around the core 46 by a polymerization or consolidation technique. The core 46 may be hollow or solid. According to one procedure, the core 46 is made by a three-dimensional printing technique. According to one embodiment, the core 46 is based on a synthetic polymer of the polyamide type, such as a material sold under the name of nylon, for example. This synthetic polymer of the polyamide type may be reinforced by reinforcing fibers, such as carbon fibers, for example.

According to one embodiment, the flexible ply 48 takes the form of a sleeve threaded around the core 46. The junction zone 19 may be obtained from 2 to 3 layers of reinforcing fibers. The flexible plies 48 of reinforcing fibers may be pre-impregnated.

According to one procedure, the core 46 has an overlength at each of its ends in relation to the junction zone 19 to be obtained. In this case, the manufacturing method comprises, after the hardening step, a step of eliminating the overlength provided at each end of the core 46 in order to obtain the junction zone 19.

To ensure greater stability during the additive manufacturing step, the core 46 comprises a tripod shape 50 at one of its ends.

After the hardening step, the manufacturing method comprises at least one lacquering step and/or at least one step of applying a protective layer and/or at least one marking step.

The manufacturing method makes it possible to economically obtain a customized and strong junction zone 19.

Although it has been described as applying to a putter, the invention is not limited to this type of golf club. As a result, the head 16, the junction zone 19 and the visual reference 40 may be used on various types of golf club.

While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.

Claims

1.-11. (canceled)

12. A golf club head comprising: a planar striking face configured to strike a golf ball,a body having a front face and at least one cavity opening into the front face,at least one ballast weight which is made of a dense material and positioned in the at least one cavity and is secured to the body,a front layer which has a first face forming the striking face and a second face opposite the first face, the second face of the front layer being in contact with the body and secured to the body, at least over an entire periphery of the front face, said front layer being made from a first material which has a Shore A hardness less than 35.

13. The golf club head as claimed in claim 12, wherein the first material is wood with a Janka hardness greater than or equal to 1500 lbf and less than 4000 lbf.

14. The golf club head as claimed in claim 12, wherein the front layer has a thickness of between 3 and 8 mm.

15. The golf club head as claimed in claim 12, wherein the at least one ballast weight is spaced apart from the front layer to obtain an intermediate zone delimited by the ballast weight, the front layer, and the body.

16. The golf club head as claimed in claim 15, wherein the intermediate zone is completely filled with at least one third material configured to dampen noise.

17. The golf club head as claimed in claim 16, wherein the first material, the dense material, and the third material are arranged such that the first material has a hardness less than the hardness of the third material, which is less than the hardness of the dense material.

18. The golf club head as claimed in claim 12, wherein the body comprises multiple cavities distributed on either side of a fastening system configured to connect the head to a shaft.

19. The golf club head as claimed in claim 18, wherein the fastening system is off-center and in that the body comprises a cavity on a first side of the fastening system and multiple cavities on a second side of the fastening system.

20. The golf club head as claimed in claim 12, wherein the body comprises multiple cavities all having a cross section that is the same in a plane parallel to the front face.

21. The golf club head as claimed in claim 12, wherein the body comprises a filler material interposed between the ballast weight and the at least one cavity, the filler material having a density which is lower than that of the ballast weight.

22. A golf club comprising: the head as claimed in claim 12.