Patent Grant
10207162
The present invention relates generally to a co-forged golf club head formed from two or more materials and the method of manufacture for such a golf club head. More specifically, the present invention relates to the creation of an iron type golf club head from a pre-form billet that already contains two or more materials before the actual forging process; resulting in a multi-material golf club head that doesn't require any post manufacturing operations such as machining, welding, swaging, gluing, and the like.
Golf is hard! When your average golfer swings a golf club, he or she may have dramatic variations in his or her golf swing, resulting in numerous off-center hits, which result in diminished performance when compared to a direct center hit. However, in an attempt to make this very difficult game more enjoyable for the average golfer, golf club designers have come up with unique golf club designs that will mitigate the harsh realities of a less than perfect golf swing.
In one early example, U.S. Pat. No. 4,523,759 to Igarashi discloses a perimeter weighted hollow golfing iron having a foam core with an effective hitting area concentrated toward the center of moment in an attempt to help make the game of golf easier. Distributing the weight of a golf club to the perimeter allow the moment of inertia (MOI) of a golf club head to be increased, reducing the undesirable twisting a golf club as it impacts a golf ball.
U.S. Pat. No. 4,809,977 to Doran et al. shows another example of an attempt to increase the moment of inertia of a golf club head by placing additional weights at the heel and toe portion of the golf club head. This increase in the moment of inertia of the golf club head achievable by increased heel and toe weighting could further prevent the golf club from twisting in a heel and toe direction, which mitigates the undesirable effect of sending a golf ball off the intended trajectory.
Although the initial attempts at increasing the forgiveness and playability of a golf club for an average golfer are admirable, it does not take advantage of the extreme forgiveness that can be achievable by utilizing different materials to form different portions of the golf club head. In one example, U.S. Pat. No. 5,885,170 to Takeda shows the advantage of using multi-materials to create more extreme adjustment of the mass properties. More specifically, U.S. Pat. No. 5,885,170 teaches a body having a face formed of one material while a hosel is formed from another material having different specific gravity from that of the head body. U.S. Pat. No. 6,434,811 to Helmstetter et al. shows another example of utilization of multiple materials to improve the performance of a golf club head by providing a golf club head with a weighting system that is incorporated after the entirety of the golf club head has been formed.
More recently, the improvements in incorporating multi-materials into a golf club head have matured significantly by incorporating numerous multiple materials of different characteristics by machining cavities into the golf club head. More specifically, U.S. Pat. No. 7,938,739 to Cole et al. discloses a golf club head with a cavity integral with the golf club head, wherein the cavity extends from the heel region to the toe region; extending along a lower portion of the back face of the golf club head; extends approximately parallel to the strike face; and is approximately symmetrical about a centerline that bisects the golf club head between the heel region and the toe region.
However, as multiple materials are introduced into the golf club after the body has been completed, the tolerances of the interfaces between the different materials could potentially cause undesirable side effects of altering the feel of the golf club head. U.S. Pat. No. 6,095,931 to Hettinger et al. identifies this specific undesirable side effect of sacrifice in the feel by the usage of multiple different components. U.S. Pat. No. 6,095,931 addresses this issue by providing an isolation layer between the golf club head and the main body portion that comprises the striking front section.
U.S. Pat. No. 7,828,674 to Kubota recognizes the severity of this problem by stating that hollow golf club heads having viscoelastic element feels light and hollow to the better golfer, hence they do not prefer such a golf club. U.S. Pat. No. 7,828,674 address the deficiencies of such a multi-material golf club by incorporating a block of magnesium to be embedded and or press-fitted into the recess formed in the metal only to be sealed with a metallic cover.
Despite all of the above attempts to improve the performance of a golf club head all while trying to minimize the sacrifice in feel of a golf club, all of the methodologies require a significant amount of post manufacturing operation that creates cavities and recesses in the club head for the secondary material to be incorporated. These types of secondary operations are not only expensive, but the ability to maintain tight enough tolerances and bonds between the various components makes it very difficult to maintain the solid feel generally associated with an unitarily formed golf club head.
Hence, it can be seen from above, despite all of the development in creating a golf club head that's more forgiving without sacrificing the feel associated with a conventional club head, the current art is incapable of creating such a club without utilizing severe post manufacturing machining that causes bad feel.
In one aspect of the present invention, a forged golf club head comprising a body portion having a striking surface made out of a first material, and at least one weight adjustment portion made out of a second material encased within the body portion; wherein the at least one weight adjustment portion is encased monolithically within the body portion of the golf club head without any secondary attachment operations.
In another aspect of the present invention, a method of forging a golf club head comprising the steps of creating a cylindrical billet out of a first material, machining one or more cavities within the cylindrical billet, partially filling the one or more cavities with a second material to create a weight adjustment portion, filling the remaining volume of the one or more cavities with the first material to encase the weight adjustment portion, and forging the cylindrical billet to create a body portion of the golf club head; wherein the body portion monolithically encases the weight adjustment portion within a body of the golf club head without any secondary attachment operations.
In another aspect of the present invention is a forged golf club head comprising a body portion having a striking surface made out of first material, and at least one weight adjustment portion made out of a second material encased within the body portion; wherein the at least one weight adjustment portion is encased monolithically within the body portion without any secondary attachment operations. The first material has a first flow stress at a first forging temperature and the second material has a second flow stress at a second forging temperature, wherein the first flow stress and the second flow stress are substantially similar to one another, and the first forging temperature and the second forging temperature are substantially similar to one another. The first material has a first thermal expansion coefficient and the second material has a second thermal expansion coefficient, wherein the first thermal expansion coefficient is greater than or equal to the second thermal expansion coefficient.
These and other features, aspects and advantages of the present invention will become better understood with references to the following drawings, description and claims.
The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.
The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Various inventive features are described below that can each be used independently of one another or in combination with other features. However, any single inventive feature may not address any or all of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below.
Before moving onto subsequent figures, it is worthwhile here to emphasize that the current golf club head 100 is created using a forging process and the weights are incorporated without any post finish machining operations. This is an important distinction to establish because the same result of a monolithically encasing a weight adjustment portion is extremely difficult to achieve using alternative manufacturing processes such as casting. “Monolithically encased”, as referred to in the current patent application, may generally be defined as a having a specific internal component placed inside a separate external component without joints or seams in the finished product. With respect to the current invention, having weight adjustment portions “monolithically encased” within the body portion 102 of the golf club head 100 may generally refer to the ability to have weight adjustment portions placed inside the body portion 102 of the golf club head without joints or seams that are generally required by post manufacturing processes such as milling, welding, brazing, gluing, or swaging. In examples, the encasement technology herein results in a single material exterior of a clubface, which also allows for more uniform surface conditioning processes, such as chrome plating. For instance, chrome plating a single material is more feasible than attempting to chrome plate two different materials. While individual materials can be chrome plated, the different materials are generally required to be plated in separate operations. Other surface conditioning processes, such as physical vapor deposition (PVD) coating and texturing, also benefit from having a uniform exterior of a club face.
It should also be noted here that a weight that is “monolithically encased” within the current definition of the present invention could potentially have certain aspect of the internal weights exposed in the finish product to illustrate the existence of a weight adjustment portion without departing from the scope and content of the present invention. More specifically, “monolithically encased” refers to the methodology used to create the ultimate product as described above, and may not necessarily be limited to visually concealing the weight adjustment member.
Moving onto
Finally,
Although the above discussion regarding the forging of golf clubs incorporated by reference do a good job describing the actual forging process, it fails to address the additional concerns with the co-forging process of the current invention wherein two different materials are involved in this forging process. More specifically, because a weight adjustment portion 215 is made out of a second material that could be different from the first material used to create remainder of the pre-form billet 201, special care must be taken to ensure that the different materials can be forged together to form a golf club head 200. Hence, in order to select two cohesive materials that are capable of being co-forged together, the first material and the second material may generally have to have very specific material properties requirements with respect to their flow stress and their thermal expansion coefficient. Although it is most preferential for the two materials to have identical material properties yielding consistency in forging, the usage of identical materials may not offer any weight adjustment benefits required for the basis of the current invention.
First off, in order for metallic materials to have the capabilities of being co-forged together, the respective flow stress of each of the materials needs to be properly considered. Flow stress of a material, may generally be defined as the instantaneous value of stress require for continued deforming of the material (i.e. to keep the metal flowing); and the creation of a cohesive forged component from two different materials will require them to flow at relatively the same speed when subjected to the stresses of the forging process. It is commonly known that the flow stress of a material is generally a function of the yield strength, the flow stress of a material may generally be summed up by Eq. (1) below.
Yf=Ken Eq. (1)
wherein
Yf=Flow Stress (MPa)
K=Strain Coefficient (MPa)
n=Strain Hardening Exponent
In addition to the above equation, it is worthwhile to mention here that the flow stress of a material may not be construed in vacuum, but rather, it is a function of the forging temperature of the material as well. Hence, in a current exemplary embodiment of the present invention, a first flow stress of the first material at its first forging temperature is substantially similar but not identical to the second flow stress of the second material at its second forging temperature; with the first forging temperature and the second forging temperature being substantially similar. More specifically, in a more detailed embodiment, the first material may be 1025 steel having a first flow stress of about 10 ksi (kilo-pound per square inch) at a forging temperature of about 1,200° C., while the second material may comprise a Niobium material having a second flow stress of also about 12 ksi at a forging temperature of about 1,100° C.
Although in the exemplary embodiment of the present invention described above, the first material may be a 1025 steel and the second material may be a Niobium material, various other materials may also be used without departing from the scope and content of the present invention so long as their flow stresses are similar at a similar forging temperature. Alternatively speaking, any two materials may be used in the current co-forging process so long as the second flow stress is no more than 20% greater or no less than 20% lesser than the first flow stress.
As mentioned before, other than flow stress, the thermal expansion coefficient of the first and second materials are also important to the proper co-forging of two distinct materials. More specifically, a first thermal expansion coefficient of the first material may generally need to be greater than or at least equal to the second thermal expansion coefficient of the second material. Because the thermal expansion coefficient also relates to the shrinkage of the material after forging, it is important that the first material that monolithically encases the second material have a higher thermal expansion coefficient to prevent gaps from forming at the interface portion of the materials. In a more detailed embodiment of the present invention, the first material may be 1025 steel having a thermal expansion coefficient of about 8.0 μin/in° F., while the second material may be Niobium having a second thermal expansion coefficient of about 3.94 μin/in° F.
It should be noted that although in the above exemplary embodiment the second thermal expansion coefficient is smaller than the first thermal expansion coefficient, the numbers can be identical to achieve perfect mating of the two materials without departing from the scope and content of the present invention. In fact, in one exemplary embodiment of the present invention, it may be preferred for the first material and the second material to have the same thermal expansion coefficient, as excessive shrinkage of the outer material upon the inner material could potentially create additional stresses at the interface portions of the two materials.
Alternatively, in an attempt to provide different weighting characteristics, the second material could be made out of a 6-4 Titanium material to reduce the weight of the weight adjustment portion 215. The Titanium material may generally have a flow stress of about 10 ksi at a forging temperature of about 1,100° C. and a thermal expansion coefficient of about 6.1 μin/in° F.
Now that the forging process, and the specific concerns involving the co-forging of different materials have been discussed,
Before moving onto a discussion regarding different embodiments of the present invention, it is worthwhile here to note that the exact placement of the weight adjustment portion 215 within the body portion 202 of the golf club head 200 is slightly different in every single different club head, this is the outcome of the current inventive co-forging process involves different materials. More specifically, the exact placement of the weight adjustment portion 215 may differ with each single golf club 200, as the flow stress of the first material and the second material will help determine the final location of the weight adjustment portion 215. In addition to the above, it should be noted that the interface between the weight adjustment portion 215 and the body portion 202 of the golf club head 200 may generally be an irregular interface, with the boundaries jagged to indicate that the entire golf club head 200 has been co-forged. This is dramatically different from a cavity created via a post machining secondary operations such as milling and drilling; which generally have clean bifurcation lines of the two different materials.
Similar to the methodology described above, the co-forging of the third material within the cavity created within the first material, the third material may generally need to have a third flow stress that is similar with the first flow stress of the first material and a third thermal expansion coefficient less than the first thermal expansion coefficient of the first material. More specifically, in one exemplary embodiment of the present invention, the third material may be a 6-4 Titanium material having a third flow stress of about 10 ksi at a forging temperature of about 1,100° C. and a third thermal expansion coefficient of about 6.1 μin/in° F.
Although
More specifically
It is worth noting here that in this current exemplary embodiment, the hosel portion 504 of the golf club head 500 is deliberately made from the conventional first material, as the bending characteristics of the second material used to form the weight adjustment portion 514 may generally not be suitable for the bending requirements of an iron type golf club head 500. More specifically, the third material used to form the weight adjustment portion 514 could be a lightweight iron-aluminum material having a density of less than about 7.10 g/cc, more preferably less than about 7.05 g/cc, and most preferably less than about 7.00 g/cc, all without departing from the scope and content of the present invention. However, numerous other materials can also be used as the third material used to form the weight adjustment portion 514 without departing from the scope and content of the present invention so long as the third material has a density within the range described above.
The materials in a pre-formed billet may also be selected to modify additional properties of a golf club head other than the weight and weight distribution thereof. For example, materials may be selected to adjust the coefficient of restitution (COR) of a golf club head or, more specifically, a striking face of a golf club head. A higher COR for a striking face is generally desired as a higher COR generally corresponds to a higher velocity of a golf ball when struck by the golf club. The COR of a golf club may be increased by increasing the compliance of the striking face portion of the golf club. One way to increase the compliance is to decrease the thickness of the striking face. Reducing the thickness of the striking face, however, often reduces the durability of the face. Due in part to that disadvantage, another way to increase the compliance of the striking face is provided herein. By selecting materials having lower values for their respective Young's Modulus in a pre-formed billet, the striking face may be forged to have a higher compliance and COR than a standard striking face made of a single material.
To increase the compliance of a striking face forged from the pre-formed billet 600A, the materials of the continuous outer layer 601A and the inner layer 615A are selected to have different elastic properties, such as different values for their respective Young's Modulus. In an example, the inner layer 615A has a lower Young's Modulus than the continuous outer layer 601A. In examples, the continuous outer layer 601A material may have a Young's Modulus greater than about 130 GPa, 150 GPa, or 170 GPa. In examples, the inner layer 615A material may have a Young's Modulus below about 130 GPa, 115 GPA, 95 GPa, 90 GPa, or 80 GPa. For instance, the continuous outer layer 601A may be made from a steel and the inner layer 615A may be made from titanium, titanium alloys, beta titanium alloys, copper and copper alloys including brasses and bronzes, vanadium and vanadium alloys, zirconium and zirconium alloys, silicon and silicon alloys, hafnium and hafnium alloys, niobium and niobium alloys, scandium and scandium alloys, manganese and manganese alloys, yttrium and yttrium alloys, along with some rare earths and other similar materials having a lower Young's Modulus than the steel or other material forming the continuous outer layer 601A. These materials may also form one or more of other portions of a golf club head, such as a crown or sole of the golf club head. Other considerations for selecting the inner layer 615A material include the desirability for strength properties to accommodate the high stress associated with use. For instance, the inner layer 615A material may have a yield strength of greater than about 500 MPa, 600 MPa, 700 MPa, 750 MPa, 850 MPa, or 950 MPa, depending on the particular application. The inner layer 615A material may also be selected such that it bonds well with the continuous outer layer 601A material. The flow stresses and thermal expansion coefficients may also be considered in selecting materials, as discussed above. In a specific example, the continuous outer layer 601A may be made of a 17-4PH steel having a Young's Modulus of about 200 GPa and a beta titanium alloy Ti-15-3-3-3 having a Young's Modulus of about 80 GPa. In that example, the Young's Modulus of the striking face formed from the pre-formed billet 600A may be about 140 GPa if the continuous outer layer 601A and the inner layer 615A have approximately equal thicknesses. To further lower the Young's Modulus of the striking face, the amount of titanium alloy included in the pre-formed billet 600A may be increased.
The material for the continuous outer layer 601A may also be selected depending on how the forged striking face is to be attached to the remainder of the golf club head, such as a crown and a sole of golf club. For example, where the striking face is to be attached to the remainder of the golf club head via welding, the welding process forms a stronger bond when the two materials being joined are of the same class, e.g., a plain carbon steel with a plain carbon steel, a stainless steel with a stainless steel, a titanium alloy with a titanium alloy, and so forth. Accordingly, the material for the continuous outer layer 601A may be selected to be in the same class as the material of the club head to which the continuous outer layer 601A will be attached after forging.
In some examples, such as with drivers or fairway metals, the remainder of the club face to which the continuous outer layer 601A is to be attached is made of a titanium material. For instance, a crown and a sole of a driver, to which a striking face is to be welded, may be made of a titanium material. In such examples, the continuous outer layer 601A may also be made of a titanium material to facilitate a stronger weld. Further, the inner layer 615A incorporated into the striking face may then be made of a material having a higher Young's Modulus than the titanium material of the continuous outer layer.
In examples, the inner layer 615A is substantially centered within the continuous outer layer 601A. As such, during forging, the inner layer 615A may be substantially centered on the striking face. Once the pre-formed billet 600A is forged into a striking face of a golf club head, the inner layer 615A may be substantially centered between a top portion of the golf club head and a bottom portion of the golf club head, similar to the forged placement of the weight adjustment portion 514 in
In some examples, the pre-formed billet 600A may be forged in forging direction 605, resulting in a forged face 600B having a forged continuous outer later 601B and a forged inner layer 615B, as shown in
As discussed above, the forged face 600B may incorporated as a striking face 702 of a driver 700, as shown in
In some examples, the pre-formed billet 900A may be forged in forging direction 905, resulting in a forged face 900B having a forged continuous outer later 901B, a forged continuous middle layer 910B, and a forged inner layer 915B, as shown in
Other than in the operating example, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, moment of inertias, center of gravity locations, loft, draft angles, various performance ratios, and others in the aforementioned portions of the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear in the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the preceding specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used. Further, the shapes depicted herein may be substituted for additional geometric shapes depending on the requirements or needs of a particular application. For instance, while the pre-formed billets have generally been depicted as cylindrical throughout the present disclosure, the billets may have a different shape, such as an extruded oval, a rectangular prism, a pentagonal prism, a hexagonal prism, or any other multi-sided prism.
The drawings provided herein have not necessarily been drawn to scale and it should be appreciated that different dimensions, sizes, and relative thicknesses of layers may vary depending on particular applications.
It should be understood, of course, that the foregoing relates to exemplary embodiments of the present invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
The present application is a Continuation-In-Part of U.S. patent application Ser. No. 14/589,079, filed on Jan. 5, 2015, which is a divisional of U.S. patent application Ser. No. 13/305,087, filed on Nov. 28, 2011, now U.S. Pat. No. 8,926,451, the disclosures of which are incorporated by reference in their entireties. To the extent appropriate, a claim of priority is made to each of the above-referenced applications.
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| Child | 14963070 | US |
