Golf club head with textured faceplate and methods of manufacturing the same

Embodiments of a golf club head with a textured strikeface and methods to form said club head through laser shock treatment are generally described herein. The golf club head can comprise a body and a strikeface. The strikeface has a textured front surface, with an array of indentions. Each indention can have a footprint area of between 0.01 μm2 (1×10−8 mm2) to 250,000 μm2 (0.25 mm2). The textured front surface can affect the spin imparted to a golf ball upon impact. Other embodiments may be described and claimed.

FIELD

The present disclosure relates generally to golf equipment, and more particularly, to golf club heads with textured strikefaces. The surface texture or coefficient of friction of a strikeface can affect the characteristic time of the golf club head and the spin imparted to a golf ball upon impact. Certain surface textures can also increase the fatigue and wear resistance of the golf club head.

BACKGROUND

Laser shock peening (LSP) is a process that creates an array of laser shock impact zones. In the golf industry, this technology has been used only to treat a strikeface to increase the hardness of the striking face. Laser shock peening a strikeface creates forged indentions (or wells) in a front surface of the strikeface. During the laser shock treatment, a laser is shown through a confinement layer and into an absorptive layer, which lies on top of the strikeface that is being treated. The energy from the laser beam is absorbed by the absorptive layer, causing this layer to quickly turn into plasma. The quick production of plasma causes a shockwave that deforms the strikeface front surface like a hammer, creating indentions in the surface. The intensity of the laser affects the amount of plasma that is produced. In turn, the amount of plasma affects the strength of the shockwave, which corresponds to the indention depth (or well depth).

Laser shock peening (LSP) has been used to introduce residual compressive stress into certain portions of the strikeface, creating a stress gradient between the treated and untreated portions of the strikeface. Each laser pulse treats an area of greater than 4 mm2, which corresponds to the size of the laser beam. The art has only achieved treating strikeface regions sized 4 mm2or greater, which fails to sufficiently alter the coefficient of friction between the strikeface and a golf ball. There is a need in the art for a strikeface having a fine texture, (with indentions (or wells) that are smaller than 4 mm2) which exhibit a coefficient of friction that provides desired launch and spin rate characteristics at impact with a golf ball. There is also a need in the art for strikefaces with improved durability and resistance to fatigue and crack propagation.

All printed publications cited herein are incorporated herein by reference in the entireties, except for any definitions, subject matter disclaimers or disavowals, and except to the extent that the incorporated material is inconsistent with the express disclosure herein, in which case the language in this disclosure controls.

The invention described herein is a golf club head having a textured surface with a plurality of indentions. The textured surface can be a strikeface front surface, a strikeface rear surface, or a body surface, such as a sole surface. In some embodiments, multiple surfaces are textured. The strikeface front surface, strikeface rear surface, and/or the sole surface can be textured through a laser shock surface patterning (LSSP), treating, or texturing process that resembles but distinctly differs from a laser shock peening (LSP) process. The instant LSSP process is different from the existing LSP process because the LSSP process results in a higher coefficient of friction between a treated surface and a golf ball. The instant laser shock surface patterning process creates forged indentions that are significantly smaller (i.e. having a footprint area of 0.01 μm2(1×10−8mm2) to 250,000 μm2(0.25 mm2)), than the prior art indentions (i.e. having a footprint area of 4,000,000 μm2(4 mm2) or greater), which are created with a previous LSP process. The herein described laser shock surface patterning (LSSP) process also creates well-defined boundaries to the forged indentations (or wells). The textured surface, described herein, can comprise a higher coefficient of friction than a surface lacking a LSSP texture. For embodiments with a textured strikeface front surface, the plurality of indentions can improve shot performance, especially under wet conditions. In particular, texturing the strikeface using a LSSP process can lower launch angle, increase ball spin, and maintain ball speed.

The indentions created using LSSP have well-defined boundaries that control the resulting coefficient of friction between a strikeface and a golf ball. For low-lofted club heads, the spin rate and ball flight trajectory, such as launch angle, of an impacted golf ball can be improved by an increased coefficient of friction, especially under wet conditions. Treating at least one surface of the strikeface using LSSP can create a finer grain structure and introduce compressive residual stress, improving fatigue resistance, durability, and energy storage mechanics. The herein described LSSP process can also be used to relieve stress within weld zones and can create more aerodynamic surfaces.

Definitions

The golf club head described herein can have a loft angle, measured as the angle between the ground plane and a plane tangent to a centerpoint of the strikeface. In general, driver-type club heads comprise lower loft angles than iron or wedge-type club heads.

“Low-lofted” as used herein, can refer to a golf club head having a loft angle of less than 18 degrees. “High-lofted” as used herein, can refer to a golf club head having a loft angle of 18 degrees or greater. However, for some designs the cutoff value of 18 degrees can shift by up to plus or minus 4 degrees, based on the desired performance goals of particular golf club heads.

“Laser shock peening,” abbreviated “LSP,” as used herein, is a process of treating a surface by forging indentions that are equal to the spot size of a laser beam used during the process. The laser beam spot size (and a resulting indention footprint size) is equal to or greater than 4 mm2or equal to or greater than 5 mm2. A LSP process can comprise placing an absorptive layer on top of the surface being treated, placing a confinement layer on top of the absorptive layer, shining a laser through the confinement layer to cause the absorptive layer to turn into plasma. The creation of plasma causes a shockwave that deforms or forges the surface underneath the absorptive layer, creating indentions that match the spot size of the laser beam.

“Laser shock surface patterning,” abbreviated “LSSP,” as used herein, is a process of treating a surface, to give it texture, by forging at least one plurality of indentions (multiple indentions) that each have a footprint area between 0.01 μm2(1×10−8mm2) to 250,000 μm2(0.25 mm2). In other words, each indention has a footprint area that is significantly smaller than a spot size of a laser beam used during the LSSP process. The LSSP process uses a mask layer (also called a mesh) to block the laser beam from affecting certain regions of the surface being treated. In this way, the mask layer enables the creation of many miniature indentions with each single laser shock. A LSSP process can comprise placing a mask layer (mesh) on top of the surface being treated, placing an absorptive layer on top of the mask layer, placing a confinement layer on top of the absorptive layer, shining a laser through the confinement layer to cause the absorptive layer to turn into plasma. The creation of plasma causes a shockwave that move through apertures of the mask layer to deform or forge the surface underneath the apertures, creating indentions that match the aperture size of the mask layer. The parts of the surface covered by the material of the mask (mesh) are protected from the shockwave and therefore remain unforged.

“Golf ball” as used herein, refers to a urethane covered golf ball. The coefficients of friction described below were measured between a metallic strikeface and a urethane covered golf ball.

“Treated surface” as used herein, can be understood to include a treated surface layer and adjacent material layers that are affected during surface treatment. In other words, “treated surface” can refer to any material that exhibits an altered grain structure after the LSSP process. When used in the context of a coefficient of friction discussion, “treated surface” can refer to only the exposed surface layer. In these instances, the “treated surface” can have a measurable coefficient of friction with respect to an outside object, such as a golf ball.

“Launch angle” as used herein, refers to an angle between the ground plane and an average trajectory of a golf ball, at or shortly after an impact between the golf ball and a golf club head.

“Dry conditions” as used herein, can refer to a state where the strikeface does not have visible moisture on its front surface. “Dry conditions” can also refer to weather conditions devoid of rain, dew, condensation, or other forms of moisture that would interfere with the contact between a golf ball and the strikeface of a golf club head.

“Wet conditions” as used herein, can refer to a state where the strikeface has visible moisture on its front surface. “Wet conditions” as used herein, can also refer to weather conditions including rain, dew, condensation, or other forms of moisture that would interfere with the contact between a golf ball and the strikeface of a golf club head. Taking a shot from tall grass is also considered a wet condition.

“Flat” or “level” surfaces, as used herein, can refer to surfaces having an Ra value that is at or below approximately 1 μm (1000 nm). In some embodiments, “flat” or “level” surfaces can have Ra values of less than 0.02 μm (20 nm).

DETAILED DESCRIPTION

The herein described textured strikeface surfaces and/or the textured body surfaces comprise an array of forged indentions. The forged indentions (or wells) each have a surface footprint area and a maximum depth. The footprint area of each indention ranges between 0.01 μm2to 250,000 μm2. The depth of each forged indention ranges between 0.1 μm to 15 μm. In addition to altering the surface texture, the laser shock surface patterning (LSSP) process compresses the material grain structure of the treated surface. Indention texturing controls the coefficient of friction of the treated surface, with respect to a golf ball surface. When the strikeface is the treated surface, the coefficient of friction increases, which can improve shot performance by lowering launch angle, increasing ball spin, and maintaining ball speed. Indention texturing can also control the residual stresses (related to the compressed/forged configuration of the material) and the aerodynamic properties of the treated surface. Additional benefits of indention texturing can include, but are not limited to, a slowing of crack propagation, a reduction in material fatigue, and/or an increase in energy storage during impact.

The golf club head10described herein can comprise a body24and a strikeface12. The body24defines a front, a rear opposite the front, a top rail30, a sole36opposite the top rail30, a sole leading edge40at a junction of the strikeface12and the sole36, a toe end42, a heel end44opposite the toe end42, and a hosel46connected to the heel end44. When the golf club is in an address position, the top rail30forms a top of the club head10, and the sole36forms a bottom of the club head10. The strikeface12comprises a geometric center14. The strikeface12forms a striking surface for impacting a golf ball. In some embodiments, the strikeface12is formed by a faceplate, which fits into an indention in the front of the body24.

The strikeface12can comprise a front surface16and a rear surface (not illustrated) opposite the front surface16. The sole36can comprise a sole surface. At least a portion of the sole surface can be configured to engage the turf or ground when a golfer uses the golf club. The top rail30can comprise a top rail surface. The golf club head can be a driver, a fairway wood, a hybrid, or an iron type golf club head. Driver, fairway wood, and hybrid type club heads can comprise a crown rather than a top rail.

The golf club head10can be textured with one or more indention arrays50, spread across one or more of the strikeface front surface16, the strikeface rear surface, and/or the sole surface. Any indention array50can also be called a plurality of indentions, a textured array, a surface texturing, and/or a frictional geometry. The texture on the strikeface front surface16, the strikeface rear surface, and/or the sole surface can be formed using a laser shock surface patterning (LSSP) process. As described below, the strikeface rear surface and/or the sole surface can be textured similar to the strikeface front surface16. In some embodiments, only the strikeface front surface16is textured with indention array50. In some embodiments, only the strikeface rear surface is textured with an indention array50. In some embodiments, only the sole surface is textured with an indention array50.

In other embodiments, the strikeface front surface16can have one or more pluralities of indentions50. For example, the strikeface front surface16can be textured with a first plurality of indentions50(a first array) and the strikeface rear surface can be textured with a second plurality of indentions (a second array). In yet other embodiments, the strikeface front surface16can be textured with a first plurality of indentions50(a first array) and the sole surface can be textured with a second plurality of indentions (a second array). Alternately, the strikeface front surface16can be textured with a first plurality of indentions50(a first array), the strikeface rear surface can be textured with a second plurality of indentions (a second array), and the sole surface is textured with a third plurality of indentions (a third array). In some embodiments, a single textured surface can comprise multiple indention arrays50.

The golf club head can be formed from a metal material. In some embodiments, the strikeface12can be formed from a different metal than the remainder of the club head10. Examples of metals may include, for example, but not limited to, steel, steel alloy, stainless steel, stainless steel alloy, C300, C350, Ni (Nickel)—Co(Cobalt)—Cr(Chromium)—Steel Alloy, 8620 alloy steel, S25C steel, 303 SS, 17-4 SS, carbon steel, maraging steel, 565 Steel, AISI type 304 or AISI type 630 stainless steel, titanium alloy, Ti-6-4, Ti-3-8-6-4-4, Ti-10-2-3, Ti 15-3-3-3, Ti 15-5-3, Ti185, Ti 6-6-2, Ti-7s, Ti-9s, Ti-92, or Ti-8-1-1 Titanium alloy, amorphous metal alloy, or other similar metals. The material of the golf club head can affect the laser intensity needed to attain certain indention parameters, such as the maximum indention depths described below.

Strikeface Front Surface Texturing

Referring toFIGS. 2-5, the strikeface front surface16comprises a textured region48. The textured region48can have a surface roughness that is different than the surface roughness of the remainder of the strikeface front surface16. The different surface roughness of the textured region48can be created by applying a laser shock surface patterning (LSSP) process to the textured region48to create a plurality of indentions50. The textured region48can cover between 20% and 100% of the strikeface front surface16. In the embodiment ofFIG. 2, the textured region48covers the entire front surface16(approximately 100% of the front surface16). In some embodiments, the textured region48can cover between 20%-30%, 30%-40%, 40%-50%, 50%-60%, 60%-70%, 70%-80%, 80%-90%, or 90%-100% of the front surface16. In some embodiments, the textured region48covers 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% of the front surface16.

In some embodiments, such as the embodiment ofFIG. 3, the textured region48can be located within only a portion of the strikeface12that also comprises conventional grooves130. In other embodiments, a majority of the textured region48can be located in a low region20of the strikeface12. The low region20can be any part of strikeface12below a horizontal reference axis72that extends through the geometric center14of the strikeface. In other embodiments, a majority of the textured region48can be located in a high region22of the strikeface12. The high region22can be any part of strikeface12above the horizontal reference axis72. In some embodiments, the textured region48can comprise a height58, measured from the sole36to the top rail30, greater than 0.2 inch, greater than 0.4 inch, greater than 0.6 inch, greater than 0.8 inch, greater than 1.0 inch, greater than 1.2 inch, greater than 1.4 inch, greater than 1.6 inch, greater than 1.8 inch, or greater than 2 inch. Positioning the textured region48primarily within the low region20or the high region22of the strikeface12can alter the spin imparted to the golf ball on low or high hits, respectively. In some embodiments, the strikeface front surface16can be selectively textured in certain regions to make a strikeface12that responds with roughly equivalent spin regardless of where the golf ball impacts the strikeface12. Selectively texturing one or more portions of the strikeface front surface16can also alter the residual (internal) stress of the strikeface, changing the durability, the deformation characteristics, and the energy storage mechanics of the strikeface.

As illustrated in the closeup perspective views ofFIGS. 4 and 5, the textured region48comprises a plurality of indentions50that give texture to the front surface16. The plurality of indentions50can also be called an indention array. The plurality of indentions50can be positioned in a pattern throughout the textured region48and across at least a portion of the strikeface front surface16. The plurality of indentions50can cover between 20% and 100% of the strikeface front surface16, similar to the coverage of the textured region50. In some embodiments, the plurality of indentions50can cover 20%-30%, 30%-40%, 40%-50%, 50%-60%, 60%-70%, 70%-80%, 80%-90%, or 90%-100% of the front surface16. In some embodiments, the plurality of indentions50can cover 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% of the front surface.

Referring toFIGS. 2, 4, and 5, the plurality of indentions50(indention array) can comprise multiple individual indentions100(also called “wells”). The plurality of indentions50can be arranged in any pattern and oriented in any direction across the club head. The layout of the plurality of indentions50can differ between embodiments. In some embodiments, the plurality of indentions50can be arranged in a pattern of rows. The plurality of indentions50can be further arranged in columns. The rows of indentions can be linearly oriented. An indention array orientation can be defined as a direction parallel to the linear orientation of the rows. The indention array orientation can be symbolized by an array axis70. In some embodiments, the plurality of indentions50(indention array) can be horizontally oriented. Referring toFIG. 2, a horizontal reference axis72is shown extending through the geometric center14of the strikeface12from the heel end44to the toe end42of the club head10. The array axis70(signifying the indention array orientation) can be offset by an angle of plus or minus 0 degrees to 90 degrees from the horizontal reference axis72. In some embodiments, the array axis70is offset from the horizontal reference axis72by +/−10 degrees, +/−20 degrees, +/−30 degrees, +/−40 degrees+/−45 degrees, +/−50 degrees, +/−60 degrees, +/−70 degrees, +/−80 degrees, or +/−90 degrees.

In some embodiments, the rows of indentions can be arcuate or curved. The rows of indentions can be concave with respect to the sole36, concave with respect to the top rail30, concave with respect to the heel end44, concave with respect to the toe end42, concave with respect to an upper toe end, concave with respect to an upper heel end, concave with respect to a lower toe end, or concave with respect to a lower heel end of the club head. In some embodiments, the plurality of indentions can extend radially from the geometric center14of the strikeface12. The plurality of indentions can form circular rows of increasing diameter about the geometric center14of the strikeface. Alternately, the plurality of indentions can form oval, elliptical, oblong, square, rectangular, triangular, or any other suitably shaped rows about the geometric center14of the strikeface12. In some embodiments, the plurality of indentions is centered about a point offset from the geometric center14of the strikeface12.

The plurality of indentions50can comprise an indention density of approximately 3,040 to 75,950 indentions per cm2(approximately 19,600 to 490,000 indentions per in2). In some embodiments, the indention density can be approximately 3,000 to 5,000, 5,000 to 10,000, 10,000 to 30,000, 30,000 to 60,000, or 45,000 to 75,950 indentions per cm2.

Referring toFIG. 3, in some embodiments, the textured region48can comprise multiple pocket regions62(also called laser spot regions/areas or laser covered regions/areas). Every pocket region62can correspond to the spot size of a laser beam used during the LSSP process. However, the LSSP process uses a mask layer (mesh) to protect portions of the surface being treated. Therefore, each pocket region62comprises a portion of masked (protected) surface area and a portion of exposed (unprotected) surface area. The exposed surface area becomes a plurality of indentions50. Creation of the plurality of indentions50occurs because parts of the pocket region62are exposed to a plasma shockwave through apertures of the mask layer during LSSP. Because of the mask layer (mesh), each pocket region62can comprise a plurality of indentions50. The pocket regions62can be circular, square, hexagonal, triangular, or any other suitable shape. The pocket regions62can be arranged in a pattern or array throughout the textured region48. The pocket regions62can be located next to one another to form rows. The pocket region62rows can be positioned between the grooves130, to texture the front surface16area between the grooves130.

In some embodiments, the pocket regions62correspond to the spot size (diameter) of a laser beam used in the LSSP process. For circular pocket regions62, each pocket region62can have a spot size (diameter) between 1 mm and 5 mm. In some embodiments, the spot size can be inclusively between 1 mm and 3 mm, 1.5 mm and 3.5 mm, 2 mm and 4 mm, 2.5 mm and 4.5 mm, 3 mm and 5 mm. For example, the spot size can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm. In some embodiments, the pocket regions62can be spaced apart from one another by approximately 0.1 mm (100 μm) or less.

Each pocket region62can comprise between 10 and 15,500 indentions. In some embodiments, each pocket region62can comprise between 10 and 100, 100 and 500, 500 and 1000, 1000 and 5000, 5000 and 10,000, 10,000 and 15,500 indentions, or any intermediate range of indentions. For example, for circular pocket regions62with a 1 mm diameter, each pocket region62can comprise between approximately 10 and 610 indentions. For circular pocket regions62with a 5 mm diameter, each pocket region62can comprise between approximately 500 and 15,500 indentions. The pluralities of indentions50within the pocket regions62give roughness to the textured region48, altering the resulting coefficient of friction between the textured region48and a golf ball.

Referring toFIGS. 4-6, each indention100of the plurality of indentions50comprises a footprint shape, as seen when viewed orthogonally from the strikeface front surface16. The footprint shape can be a parallelogram, a rectangle, a square, a diamond (or rhombus), a circle, a triangle, a pentagon, a hexagon, or any other suitable shape. In some embodiments, the footprint shape can be a shape having one continuous side, two arcuate sides, three sides, four sides, five sides, six sides, seven sides, eight sides, nine sides, or ten sides. Each indention100comprises sidewalls106, which extend into the front surface16to form the indention100. Within a plane coincident with the front surface16, the indention sidewalls106correspond to the sides of the footprint shape. In some embodiments, the plurality of indentions50can comprise indentions with different footprint shapes on the same strikeface. In some embodiments, one section of the strikeface12can have an array of a first indention shape and another section of the strikeface12can have an array of a second indention shape. For example, the first indention shape can be a hexagon, and the second indention shape can be a square. In some embodiments, a single array of indentions can comprise any combination of multiple footprint shapes. For example, a single array can comprise hexagons and triangles. For further example, a single array can comprise hexagons, squares, and triangles. For further example, a single array can comprise circles and squares. For further example, a single array can comprise rectangles and squares.

Referring toFIG. 4-8, each indention100of the plurality of indentions50on the strikeface front surface16can each comprise a bottom surface126and sidewalls106(also called sides or edges). Some indentions100can have a first sidewall108, a second sidewall110opposite the first sidewall108, an upper sidewall112, and a lower sidewall114. The sidewalls106can have a sharp, crisp geometry, compared to sidewalls formed by the conventional LSP process. Referring toFIGS. 8A and 8B, the sidewalls106connect roughly perpendicularly to the strikeface front surface16. The corner-like intersection between the sidewalls106and the strikeface front surface16can be slightly rounded.

The amount of curvature at the intersection between the sidewalls106and the front surface16can be characterized by a radius of curvature116of a reference circle that conforms to a cross-sectional outline of the intersection. The intersection's radius of curvature can also be called an exit radius. The radius of curvature116of the reference circle can be between 10 to 100 times less than a radius of curvature of an intersection of an indention formed by the LSP process. In some embodiments, the radius of curvature116can be 10 times, 20 times, 30 times, 40 times, 50 times, 60 times, 70 times, 80 times, 90 times, or 100 times less than a radius of curvature of an LSP-formed indention intersection (exit geometry). During an LSP process, each laser beam shock forms a single indention, without masking to block any part of the laser beam. The edges of the laser beam impart a mild forging action across a surface region that becomes the intersection or exit geometry of the indention. In other words, the LSP process creates indentions with sloped exit geometry rather than sharp exit geometry. Using the same laser intensity, the LSP process creates large, rounded indentions, whereas the LSSP process creates small, sharp indentions.

In the golf industry, media blasting is also used to texture surfaces. Media blasting relies on solid matter impacting the workpiece surface at high speeds to modify the morphology of the surface. Each particle of the solid matter can travel at unknown speeds and directions, leading to an overlapping of treatment, which flattens the surface. The peaks (any features higher than the starting elevation of the surface) and valleys (any feature lower than the starting elevation of the surface) can grow together, resulting in an undulating surface with sharp peaks. However, the repeated impact of the solid matter against the same surface areas and the size of the particles themselves, results in shallow valleys. Therefore, media blasting cannot provide both sharp edges and deep indentions for increased friction. In contrast, the LSSP process can provide indentions that are both deep and sharp (small radius of curvature at the intersection or exit edge).

Laser etching is another form of surface texturing used in the golf industry. Laser etching removes material from a surface by ablating the material into a vapor. The treated surface is transitioned from solid, to liquid, to gas, to liquid, and again to solid. As the metal re-solidifies, the metal is hardened. The morphology of a laser etched surface comprises shallow valleys and rounded peaks. The LSSP process can provide indentions that are both deep and sharp by using a mask layer (mesh) to guide and control a shockwave to create micro-features, referred to herein as indentions100. Neither the LSP process, nor media blasting, nor laser etching can discretely control indention parameters, such as position, spacing (separation distance), and edge sharpness (intersection radius of curvature).

The sidewalls106can connect roughly perpendicularly to the indention bottom surface126, similar to how they connect to the strikeface front surface16. In other words, the sidewalls106can form a sharp a radius of curvature with the indention bottom surface126.

Referring toFIGS. 6 and 7, in some embodiments, each indention100comprises a height122measured in a direction perpendicular to the array axis70of the indention array50. In some embodiments, the width122spans between the upper sidewall112and the lower sidewall114. For indention arrays50that are oriented horizontally, the indention height122can be measured along the strikeface front surface16in a direction from the sole leading edge40of the club head towards the top rail30. The indention height122can be the same as the indention width120, for some indentions100.

When the indentions100are formed by laser shock treatment (LSSP), the depth124of each indention100correlates to the intensity of the laser beam. The maximum indention depth124can vary slightly for different strikeface materials. For a polished carbon steel strikeface, the indention depths124described above can be achieved by a laser intensity ranging up to 2000 GW/cm2, up to 1500 GW/cm2, up to 1000 GW/cm2, up to 500 GW/cm2, up to 250 GW/cm2, up to 100 GW/cm2, up to 50 GW/cm2, up to 25 GW/cm2, up to 10 GW/cm2, up to 5 GW/cm2, or up to 1 GW/cm2. For some LSSP processes, the maximum indention depth for a given laser beam intensity can be approximated through the following equation:
y=0.0075x+0.5949
where “x” is the intensity of the laser beam and “y” is the approximate maximum indention depth124, resulting from the use of the given laser beam intensity in the LSSP process.

Each indention100comprises a bottom surface126. In some embodiments, the indention bottom surface126can have a non-uniform profile with ridges, valleys, and other complex geometries. In some embodiments, the indention bottom surface126can comprise a shockwave shape having curved contours. The shockwave shape and/or the non-uniform profile can be created through the laser shock surface patterning (LSSP) process described below. The contours of the bottom surface126can vary due to the grain structure at the indention site prior to treatment and/or due to the composition of the absorptive layer used in the LSSP process. For instance, if the absorptive layer comprises large particles, the power of the shockwave will be greater, which affects the shaping of the indention bottom surface126.

FIG. 9illustrates the results of an experiment recorded in the publication Mao, Bo & Siddaiah, Arpith & Menezes, Pradeep & Liao, Yiliang. (2018). ‘Surface Texturing by indirect laser shock surface patterning for manipulated friction coefficient,’Journal of Materials Processing Tech. vol. 257 (2018) pp. 227-233), which is incorporated herein in its entirety by reference. Since the graphs have not been modified from their original source, the “Height (μm)” vertical axes correspond to the herein defined “indention depth” measurement.FIG. 9illustrates four example surface profiles of surfaces each having a plurality of indentions. The first example surface profile (a) was created by laser shock surface patterning a polished carbon steel square plate with a laser intensity of 0.484 GW/cm2. The first surface profile (a) shows a pattern of indentions with consistent depths (roughly 0.2 μm) and widths. A bottom surface of each indention shows a slight protrusion in the center of each bottom surface. The second example surface profile (b) was created by laser shock surface treating a polished carbon steel square plate with a laser intensity of 0.554 GW/cm2. The second surface profile (b) has indentions with a greater depth (roughly 0.5 μm). The bottom surface of each indention is slightly more erratic than in the first surface profile (a).

The third example surface profile (c) was created by laser shock surface treating a polished carbon steel square plate with a laser intensity of 0.778 GW/cm2. The fourth example surface profile (d) was created by laser shock surface patterning a polished carbon steel square plate with a laser intensity of 0.890 GW/cm2. The third and fourth example surface profiles (c) and (d) comprise progressively greater depths than profiles (a) and (b). The third and fourth profiles (c) and (d) comprise peaks and erratic textures extending from the bottom surfaces. The effect of laser intensity on surface profile is further discussed below.

The plurality of indentions50of the treated region40can be characterized by an aspect ratio of indention depth124over indention width120. The aspect ratio can range between 3 and 150. In some embodiments, the aspect ratio can range between 3 and 5, 5 and 10, 10 and 20, 20 and 30, 30 and 40, 40 and 50, 50 and 60, 60 and 70, 70 and 80, 80 and 90, 90 and 100, 100 and 110, 110 and 120, 120 and 130, 130 and 140, 140 and 150, 3 and 25, 25 and 50, 50 and 75, 75 and 100, 100 and 125, 125 and 150, 3 and 50, 25 and 75, 50 and 100, 75 and 125, 100 and 150, 3 and 100, 25 and 125, or 50 and 150. A higher aspect ratio correlates to a rougher surface and a higher coefficient of friction. For aspect ratios greater than 6, “micro-effects” and “nano-effects” occur, causing the performance of the plurality of indentions50to be better than expected.

Referring again toFIG. 2, the plurality of indentions50(indention array) can be positioned in a pattern across the front surface16. The indention array50can comprise a length78, measured in a heel-to-toe direction. In some embodiments, the array length78is limited by the size of the strikeface12. In some embodiments, such as inFIG. 3, the array length78can be equal to a length of one or more face grooves130, described further below. The array length78can be between 1.5 inches and 2.5 inches. In some embodiments, the array length78is between 1.5 inches and 2.0 inches, 1.8 inches and 2.2 inches, or 2.0 inches and 2.5 inches. In some embodiments, the array length can be 1.5 inches, 1.6 inches, 1.7 inches, 1.8 inches, 1.9 inches, 2.0 inches, 2.1 inches, 2.2 inches, 2.3 inches, 2.4 inches, or 2.5 inches.

Multiple regions of the strikeface12can be treated to have indentions100with different sizes and/or depths to give regions of the strikeface different friction coefficients. Furthermore, the plurality of indentions50may be arranged or arrayed in various patterns, including similar or different shapes, to alter the coefficient of friction, the hardness, and/or the aerodynamic properties of the surface. For example, in some embodiments, the indentions100may be arrayed in a second pattern (second array) such that they are spaced apart more than in a first pattern (first array).

In addition to the indention array50, the strikeface front surface16can further comprise conventional grooves130. The grooves130can run in a heel-to-toe direction, generally horizontal when the club is in the address position. The grooves130can be spaced apart from each other in the crown-to-sole (or top rail-to-sole) direction. The grooves130can be spaced apart by a groove pitch132(distance of separation) between 2 millimeters (mm) and 3 mm (0.08 inch and 0.12 inch). In some embodiments, the groove pitch132is between 2 mm and 2.2 mm, 2.2 mm and 2.4 mm, 2.4 mm and 2.6 mm, 2.6 mm and 2.8 mm, or 2.8 mm and 3.0 mm. In some embodiments, the groove pitch132can be 2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, or 3.0 mm. The indention array50can fill or partially fill land areas between the grooves130. In some embodiments, the grooves130can have a constant width (measured crown-to-sole/top rail-to-sole) and constant land area between grooves130. In other embodiments, the grooves130can have a varying width and varying land area between grooves130.

Strikeface Rear Surface Texturing

As described above, one or more of the strikeface front surface16, the strikeface rear surface, and the sole surface can be textured. The strikeface rear surface can comprise at least one textured region, similar to the textured region48, described above. The textured region can comprise a plurality of indentions that give texture to the rear surface (not illustrated). The rear surface plurality of indentions can be similar to the front surface16plurality of indentions50. Similar to the textured front surface, the textured region on the rear surface can cover between 20% and 100% of the strikeface. In some embodiments, the textured region can cover 20%-30%, 30%-40%, 40%-50%, 50%-60%, 60%-70%, 70%-80%, 80%-90%, or 90%-100% of the rear surface. In some embodiments, the textured region can cover 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% of the rear surface. Selectively texturing one or more portions of the rear surface can alter the residual stress of rear surface, improving the durability, the deformation characteristics, and the energy storage mechanics of the strikeface16.

The plurality of indentions on the strikeface rear surface can comprise footprint shapes, footprint shape areas, indention widths, indention heights, and indention depths similar to the respective properties described above for the front surface indentions100. In some embodiments, the strikeface rear surface can have an array of a first indention shape and another section of the rear surface with an array of a second indention shape. In some embodiments with both a textured strikeface front surface and rear surface, the indention shape on the front surface can be different than the indention shape on the rear surface. In other embodiments with both a textured front and rear surface, the indention shape on the front and rear surface can be identical. Multiple regions of the rear surface can be treated to have indentions with different sizes and/or heights to give regions of the rear surface different grain structure, residual stress, and/or hardness.

As described above, the plurality of indentions can be positioned in an array or pattern across the rear surface in a manner similar to the array50on the front surface16. The rear surface array length and/or separation distance between indentions can be similar to those described above for the strikeface front surface16. The separation distance affects the density of indentions across the array and consequently changes the properties of the rear surface, such as the durability.

Sole Surface Texturing

In some embodiments, the sole surface comprises a plurality of indentions that give texture to the sole36. The sole surface can comprise at least one textured region, similar to the textured region48, described above. The textured region can comprise a plurality of indentions that give texture to the sole surface. The sole surface plurality of indentions (not illustrated) can be similar to the front surface and rear surface pluralities of indentions. Similar to the textured front surface and textured rear surface, the sole surface textured region can cover between 20% and 100% of the sole surface. In some embodiments, the sole textured region can cover 20%-30%, 30%-40%, 40%-50%, 50%-60%, 60%-70%, 70%-80%, 80%-90%, or 90%-100% of the sole surface. In some embodiments, the sole texture region can cover 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% of the sole surface. Selectively texturing one or more portions of the sole surface can alter the coefficient of friction, hardness, and/or aerodynamic properties of the sole surface. The altered coefficient of friction can improve turf interaction between the sole surface and the ground. The increased hardness of the sole surface can improve the durability of the sole. The altered aerodynamic properties can reduce drag and increase swing speed.

The plurality of indentions on the sole surface can comprise footprint shapes, footprint shape areas, indention widths, indention heights, and indention depths similar to the respective properties described above for the front and rear surface indentions. In some embodiments, the sole surface can have an array of a first indention shape and another section of the sole surface with an array of a second indention shape. In embodiments with both a textured strikeface and a textured sole, the strikeface indention shape can be different than or identical to the sole indention footprint shape. In some embodiments, multiple regions of the sole surface can be treated to have indentions with different sizes and/or depths to give regions of the sole surface different grain structure and/or different residual stress. The multiple treated regions of the sole surface can have different hardness values. The indention depth of the array on the sole surface can also affect the aerodynamic response and turf interaction of the sole surface.

As described above, the plurality of indentions can be positioned in an array or pattern across the sole36. The sole surface indention array can cover a portion of the sole or the entire sole36. The sole surface indention array can comprise a length, measured in a heel-to-toe direction. In some embodiments, the array length is limited by the size of the sole36. In some embodiments, the sole array length can be longer than the strikeface front or rear surface array length. The sole array length can be between 1.5 inches and 3.5 inches. In some embodiments, the array length is between 1.5 inches and 2.0 inches, 1.8 inches and 2.2 inches, 2.0 inches and 2.5 inches, 2.5 inches and 3.0 inches, or 3.0 inches and 3.5 inches. In some embodiments, the array length is 1.5 inches, 1.6 inches, 1.7 inches, 1.8 inches, 1.9 inches, 2.0 inches, 2.1 inches, 2.2 inches, 2.3 inches, 2.4 inches, 2.5 inches, 2.6 inches, 2.7 inches, 2.8 inches, 2.9 inches, 3.0 inches, 3.1 inches, 3.2 inches, 3.3 inches, 3.4 inches, or 3.5 inches.

The indentions of the plurality of indentions may be spaced apart from each other by a separation distance to create the sole surface indention array. The sole surface plurality of indentions can be spaced apart by a separation distance similar to the separation distance80described above for the strikeface front surface indention array50. The separation distance affects the density of indentions across the array and consequently changes the properties of the sole surface, such as the durability, aerodynamics, and/or turf interaction.

Alternate Embodiments with Crown Surface Texturing

Properties, Characteristics, and Performance

The textured or treated surfaces of the golf club head can exhibit coefficients of friction, roughness, hardness, material grain structures, and/or residual stresses unlike untreated surfaces. One or more of these parameters can affect spin rate, launch angle, and/or ball speed. Further advantages can include efficient and speedy manufacturability, increased material fatigue resistance, and/or increased wear resistance.

The size and shape of the indentions on the front surface16, the rear surface, and/or the sole surface can determine coefficient of friction for each of these surfaces. The coefficient of friction between a urethane covered golf ball and the textured front surface, the textured rear surface, and/or the textured sole surface can range between 0.05 and 0.95. In some embodiments, the textured surface coefficient of friction between a urethane covered golf ball and the textured surface can range between 0.10 and 0.30, 0.40 and 0.95, 0.40 and 0.50, 0.50 and 0.60, 0.60 and 0.70, 0.70 and 0.80, 0.80 and 0.90, or 0.85 and 0.95. In some embodiments, the textured surface coefficient of friction can be 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, or 0.95. In some embodiments, the textured surface coefficient of friction can be less than 0.1, less than 0.2, less than 0.3, less than 0.4, less than 0.5, less than 0.6, less than 0.7, less than 0.8, less than 0.9, or less than 0.95.

In some embodiments, the treated strikeface front surface16and/or sole surface comprises a higher coefficient of friction than an untreated strikeface and/or sole, respectively. In other embodiments, the treated strikeface front surface16and/or sole surface comprises a lower coefficient of friction than an untreated strikeface and/or sole, respectively. In embodiments where the indentions are formed by laser shock surface treatment (LSSP), the coefficient of friction of the textured surface is determined by the laser intensity used during manufacturing. The strikeface coefficient of friction controls the spin imparted to a golf ball upon impact. The sole coefficient of friction affects the turf interaction between the sole surface and the ground.

The coefficient of friction between the ball and the strikeface12controls the spin rate imparted to a golf ball at impact. The loft angle of the club head10can change the relationship of the strikeface coefficient of friction and the golf ball spin rate. In low-lofted clubs, a higher coefficient of friction can lead to a lower spin rate imparted to the ball, whereas in high-lofted clubs, a higher coefficient of friction can lead to a higher spin rate imparted to the ball. In most low-lofted club heads, a lower spin is desirable because it can lead to a longer carry distance. For example, lower spin increases the carry distance for a driver-type club and allows the golf ball to roll forward after landing. However, for high-lofted clubs, a higher spin rate lengthens ball flight. A higher spin rate can also causes the ball to sit or roll slightly backward upon landing, which increases shot precision.

In addition to the loft angle affecting the relationship between the coefficient of friction and the spin rate, the conditions under which the shot is taken can also affect the relationship between the coefficient of friction and the spin rate. In particular, for high-lofted club heads under dry conditions, the imparted ball spin rate can be unaffected by adding texture to the strikeface front surface. However, in wet conditions, the imparted ball spin rate can be increased by texturing the strikeface front surface16. The added texture can increase the spin rate by up to 2000 revolutions per minute (rpm). In some embodiments, the texture described herein can increase the spin rate under wet conditions by between 500 rpm to 2000 rpm, 500 rpm to 700 rpm, 700 rpm to 900 rpm, 900 rpm to 1100 rpm, 1100 rpm to 1300 rpm, 1300 rpm to 1500 rpm, 1500 rpm to 1700 rpm, 1700 rpm to 1900 rpm, or 1800 rpm to 2000 rpm. In some embodiments, under wet conditions, the added texture can increase the spin rate by between 5% and 30%, more specifically between 5% and 10%, 10% and 15%, 15% and 20%, or 20% and 30%. In some embodiments, the added texture can increase the spin rate by approximately 13.5%. Since dew or other moisture often settles and remains on grass, wet conditions tend to be more commonly encountered during golf. Therefore, improving the spin rate and other performance parameters under wet conditions is especially important to a golfer.

The increased ball spin improves shot accuracy by helping the golf ball to stick close to the location where it impacts the ground, rather than rolling forward. Furthermore, strikefaces lacking the herein described texture tend to induce lower spin rates under wet conditions than under dry conditions. For a club head with the herein described texture, the induced spin rate can be roughly equivalent under wet and dry conditions. The similarity in spin rate between wet and dry conditions can improve a golfer's ability to predict their shot distance.

Texturing the strikeface front surface16can also decrease the launch angle of a golf ball under wet conditions. In wet conditions, the strikeface front surface texture can decrease the launch angle by between 1 to 3 degrees, compared to a strikeface lacking the herein described texture. In some embodiments, the strikeface front surface texture can decrease launch angle by between approximately 1 to 1.5 degrees, 1.5 degrees to 2.0 degrees, 2.5 degrees to 3.0 degrees. Reducing the launch angle can improve shot performance for a wedge or iron type club head. Texturing the strikeface front surface16can also increase the potential ball speed imparted to a golf ball under wet conditions. On average, the strikeface front surface texture does not negatively affect ball speed.

In some embodiments, textured or treated surfaces can comprise a Vickers hardness (HV) from 70 to 90, 70 to 75, 75 to 80, 80 to 85, 85 to 90, or 75 to 85. The textured or treated surfaces can have a Vickers hardness (HV) that is 10 to 20 points greater than the hardness of an untreated surface. In some embodiments, the hardness and the fine grain structure of the plurality of indentions can reduce crack initiation and slow crack propagation on the strikeface front surface. In other words, the potential ball speed achievable by an untextured strikeface is maintained after texturing the strikeface front surface16.

As described above, the textured or treated surfaces of the golf club head can exhibit coefficients of friction, material grain structures, hardness, and/or residual stresses different than untreated surfaces. One or more of the front surface, the rear surface, and/or the sole surface (i.e. the treated surface(s)) can comprise a fine grain structure. The laser shock surface patterning process that creates the indentions on the treated surface can alter the grain structures of the material. When the treated surface undergoes a micro-forging process, the dislocations or voids at the grain boundaries are permanently compressed. This creates a finer grain structure than the original grain structure. The fine grain structure causes the treated surface to resist crack initiation and propagation because the voids at the grain boundaries are compressed. In other words, forging indentions in the strikeface can increase the fatigue resistance of the face, causing the club head to endure a greater number of impacts with a golf ball before failure.

The textured or treated surface can comprise compressive residual stress. In embodiments with a treated strikeface rear surface, compressive stress, created by the micro-forged indentions, can offset tension stress imparted to the rear surface during impact. This offset of tension stress can make the strikeface more durable and better able to store impact energy.

Employing the LSSP process can also relieve stress within weld zones. Strikefaces are often welded into a club head body to create a full golf club head. The resulting weld zones or heat-affected zones (HAZ) comprise stressed metal material that is more prone to failure than adjacent metal components. Treating the weld zones or HAZ with LSSP can improve durability by relieving stress within the welded metal material. The laser shock surface patterning process micro-forges the treated surface, which alters the texture, hardness, and material grain structure of the surface.

Finally, texturing one or more surfaces of a golf club head using LSSP can improve the aerodynamic properties of the treated surfaces. The use of texturing for aerodynamic benefit is especially useful for the crown surface and/or the sole surface. The altered surface structure created by LSSP can improve laminar flow of air over the surface. By improving laminar flow over the crown and/or sole surface, the overall drag on the club head can be reduced, increasing swing speed and resultant ball speed.

Method

Referring toFIG. 9, a method of manufacturing the strikeface, described above, comprises: providing a golf club head with a strikeface, which in some embodiments is a strikeface (step150), placing a mask layer on the strikeface front surface, and applying an absorptive layer (or ablative layer) over the mask layer (step152), placing a confinement layer over the absorptive layer (step154), concentrating a laser beam over a spot on the strikeface to forge an array or a portion of an array of indentions by laser shocking the absorptive layer (step156), aiming the laser at an untreated spot of the strikeface and repeating steps154and156until the desired portion of the strikeface front surface is treated, removing the confinement layer and the mask layer (step158), and cleaning the strikeface, if necessary. For the sake of the following discussion, the reference numerals used above for golf club head10are also used in this method description. However, the method of manufacturing the strikeface is not limited to the specific wedge-type golf club head10.

In step150of the process, providing the strikeface12can comprise casting, forging, stamping, 3D printing, or otherwise forming a strikeface12. The laser shock surface patterning (LSSP) process requires that the treated portion of the front surface be flat or level. Therefore, step100can further comprise grinding, polishing, lapping, or otherwise forming at least one flat region on the front surface16. For some golf club heads, the entire strikeface front surface16is ground, polished, lapped, or otherwise formed to be flat or level. The LSSP process is more efficient on flatter surfaces.

In step152, a mask layer140is placed over the strikeface front surface16. In some embodiments, the mask layer140can be a mesh, such as a metal mesh or wire cloth. The mask layer140can also be called a protective mold layer or mesh layer. The mask layer140can comprise apertures that correspond to the desired footprint shape of the indentions100that are created by the laser shock forging (LSSP) process. The mask layer140can be rated by the number of apertures per linear inch. The mask140can be a 400 mesh, with 400 equally-spaced apertures per inch. In other embodiments, the mask140can be a 200 mesh, 225 mesh, 250 mesh, 275 mesh, 300 mesh, 325 mesh, 350 mesh, 375 mesh, 400 mesh, 425 mesh, 450 mesh, 475 mesh, 500 mesh, 525 mesh, 550 mesh, 575 mesh, 600 mesh, 625 mesh, 650 mesh, 675 mesh, or 700 mesh. In some embodiments, several separate mask layers are used to form different indention patterns on different portions of the strikeface12.

In step154, an absorptive layer142is applied over the mask layer140. The absorptive layer142can also be called a plasma generation layer or an ablative layer. The material that forms the absorptive layer142must be carbon-based, black or very dark in color. In some embodiments, the absorptive layer material is graphite, graphene, or any other suitable carbon-based material. In some embodiments, the absorptive layer142can be a tape. The absorptive layer142can be taped, sprayed, painted, poured, laid, or otherwise applied to the mask layer140. In some embodiments with a tape-type absorptive layer142, the tape can be used to secure the mask layer140in place. The absorptive layer142absorbs energy from the laser beam146, causing the material of the absorptive layer142to turn into a plasma state. The color of the carbon-based material causes the material to absorb the energy transferred by the laser beam146applied in step156.

In embodiments that use graphene as the absorptive layer142material, the uniform geometry of the graphene platelets can absorb the laser energy more efficiently than other carbon materials. Due to its structure, graphene can have a greater surface area that is exposed to the laser beam156, compared to other carbon materials. In some embodiments, the absorptive material is a spray (or sticky paint), but in other embodiments the material is a powder. The absorptive layer142material can be provided as particles of various sizes. The size of the absorptive layer particles can affect the power of the resulting shockwave. For example, larger particles can generate more plasma, resulting is a higher power shockwave, while smaller particles result in a lower power shockwave. The absorptive layer142can further comprise air or other trace elements that are trapped within the main material of the layer.

In step154, a confinement layer144is placed over the absorptive layer142. The confinement layer144is formed from a transparent and airtight material. In some embodiments, the confinement layer144is water. In other embodiments, the confinement layer144is a sheet of glass. The sheet of glass must be flat to ensure an airtight seal against the absorptive material142. When the confinement layer144is water, the absorptive material142can be a spray, tape, or sticky paint that will not be washed away (a powder would be susceptible to being washed away). When the confinement layer144is a glass sheet, the confinement layer144is preferably a powder.

In step156, a laser beam146is concentrated over a spot on the strikeface front surface16. The energy from the laser beam146is transferred through the transparent confinement layer144(in this example water) and into the absorptive layer142. When the laser146strikes the absorptive layer142, the absorptive layer is ablated and then ionized. The laser shock converts the absorptive layer142into a plasma state. This creates a shock wave148that impacts the surfaces underneath it. The shockwave148exhibits a rapid change in pressure, temperature and density of the absorptive layer142. The mask layer140prevents the plasma from affecting the mesh-covered portions of the strikeface front surface16. However, the apertures in the mask layer140allow the plasma shock wave148to reach miniature surface portions that are exposed through the apertures. The shock wave148forges these exposed miniature surface portions into indentions100. A single pulse of the laser146can forge multiple indentions100through the plasma generation caused by the shockwave148.

The size of the laser beam146does not determine the size of the indentions100. Instead, the mask layer140determines the size of the indentions100. The indentions100correspond to the size of the apertures in the mask layer140. Using the mask layer140allows the indention size to be tailored to the desired size to create the desired texture or roughness on the strikeface front surface16. The texture of the front surface16in turn determines the coefficient of the strikeface12.

As described above, the intensity of the laser beam146can affect the coefficient of friction. In some embodiments, an increase in the intensity of the laser beam146can increase the friction coefficient. However, in some embodiments, the friction coefficient can also be initially lowered compared to an untreated strikeface. The intensity of the laser beam146can also affect the hardness of the strikeface. In some embodiments and for some strikeface materials, the hardness of the strikeface12can increase with higher laser beam intensity.

The process of laser shocking treating (LSSP) the surface can be repeated until the laser shock treatment has been applied to any areas of the strikeface12where texturing is desired. In some embodiments, the entire striking surface16is textured. In some embodiments, only a portion of the strikeface front surface16is textured. The repeating of the process is necessary because the size of the laser beam146is small in comparison to the strikeface12. In some embodiments of the method, step156of laser shocking a small surface region can be repeated between 300 to 400 times to texture the entire strikeface front surface16.

Each laser shock148, covering roughly a 3×3 mm grid (covering an area of 0.09 cm2), can be completed in between 3 and 25 nanoseconds. When further accounting for the time needed to apply the confinement layer144, the absorptive layer142, and the mask layer140, each indention100can be created in between 0.4 microseconds and 0.8 microseconds. In some embodiments, each indention can be created in 0.6 microseconds. The high speed of the forging of the indentions100, compared to slower methods lacking the mask layer140, allows the strikeface12to be manufactured quickly.

In some embodiments, the surface being treated is a curved surface. The laser shock surface patterning (LSSP) process requires a level surface across at least a local treatment region. Thus, a curved surface can be treated by dividing it into a plurality of locally flat surface regions. These flat regions enable local application of a plurality of indentions through the laser shock surface patterning process.

In step158the confinement layer144and the mask layer140are removed from on top of the strikeface12. In some embodiments, this requires draining water off from on top of the absorptive layer142. The treated surface can be cleaned after the laser shock treatment (LSSP) is complete. Any residue left from the obliteration of the absorptive layer142can be wiped off or otherwise removed from the strikeface12.

The above-describe method can be called an indirect laser shock treatment (or indirect laser shock surface patterning). In some embodiments, a method of producing the golf club head described herein comprises a direct laser shock treatment method. In a direct laser shock treatment method, the mask layer140is placed on top of the absorptive layer142, shielding the absorptive layer142from the laser beam146. In alternate embodiments of the method of forming the strikeface disclosed herein, the laser shock treatment (LSSP) can be applied to a sheet metal piece before the strikeface12is cut out of the sheet metal piece.

A method of manufacturing a strikeface rear surface, a sole surface, and/or a crown surface comprise steps similar to the steps for treating the strikeface front surface16. The manufacturing method for producing a golf club head with one or more treated surfaces can comprise: providing a golf club head body and providing a strikeface, placing a mask layer on the surface to be treated, applying an absorptive layer over the mask layer, placing a confinement layer over the absorptive layer, concentrating a laser beam over a spot on the surface to be treated to forge an indention array or a portion of an indention array by laser shocking the absorptive layer, aiming the laser at an untreated spot of the surface and repeating the laser shocking process until the desired portion of the surface is treated, removing the confinement layer and the mold layer, and cleaning the surface, if necessary. This method can be applied to a strikeface rear surface, a sole surface, and/or a crown surface. In some embodiments, one or more of the strikeface front surface, the strikeface rear surface, the sole surface, and/or the crown surface are treated according to this manufacturing method more than once. Treating a surface more than once can alter the shape of the indentions, increase the hardness of the surface, and/or alter the depth of the indentions.

Production Apparatus

Manufacturing the strikeface12having the herein described texture can require a production apparatus. Typically, the production apparatus includes a means of securing a strikeface12, a crown insert, a sole insert, and/or a golf club head body comprising a crown and sole. The production apparatus further includes a casing that secures and/or bounds the mask layer140, the absorptive layer142, and the confinement layer144.

In some manufacturing scenarios, sourcing a mask layer (or mesh) that is the size of the strikeface can be costly for producing indentions with a width of 1.2 μm or less. Therefore, to cut down production costs, small meshes, commonly known as TEM grids, can be used in place of a strikeface-sized mask layer. TEM grids are readily available on the market and affordable because they are commonly used in transmission electron microscopy.

In some embodiments, the production apparatus can comprise a foundation plate that holds the club head, a frame, and a plurality of pins (not shown) to releasably secure the frame to the foundation plate. The frame can slide when the plurality of pins is not in place.FIGS. 12 and 13illustrate a production apparatus200lacking a means of holding a club head, but operates in the same manner as a production apparatus with a means of holding a club head. The frame230sits on top of the foundation plate210. The frame230houses the TEM grids. The frame230is secured in either a first position or a second position relative to the foundation plate210.FIG. 13shows the frame230in the second position. In the first position, the frame230can be located slightly above where it would be in the second position. Since the frame230determines where the laser shock surface treatment is given, the position of the frame230controls what areas of the strikeface are treated.

Referring toFIGS. 13 and 14, the foundation plate210comprises a top surface212, a bottom surface (not shown), a means of clamping a golf club head (not shown), a plurality of bores for receiving fastening members218, and a plurality of pin holes222,228for receiving pins. In some embodiments, a cavity (not shown) is formed in the top surface212. The cavity is shaped to hold a golf club head with the strikeface facing upwards. The strikeface can be positioned parallel to the top surface212.

The foundation plate210itself can be secured to a laser table via the plurality of bores218and fastening members (not shown). In some embodiments, clamps or other fastening mechanisms are used to hold the golf club head in the cavity. In some embodiments, the top surface212of the foundation plate210comprises two tracks228which engage the frame230, allowing it to slide from the first position to the second position. In other embodiments, the foundation plate top surface212lacks the tracks228. In these embodiments, the frame230can be lifted and moved from the first position to the second position.

The frame230comprises a top surface232and a bottom surface (not shown). Typically, the frame230is formed from a thick sheet of metal. The frame230comprises a plurality of apertures238, sized to receive the TEM grids. The plurality of apertures238is arrayed across the frame230. Each aperture extends through the frame230from the top surface232to the bottom surface. Each aperture can comprise a diameter. The apertures238can be spaced apart by a distance less than the diameter of an aperture. The plurality of apertures238can comprise between 40 to 80 apertures. In some embodiments, the plurality of apertures238comprises 40, 45, 50, 55, 60, 65, 70, 75, or 80 apertures.

The frame230further comprises clamp tabs236. The clamp tabs236extend out from two or more sides of the frame230. The clamp tabs236allow the frame230to be secured to the work table and/or the foundation plate210. Securing the frame230is important for maintaining a watertight seal between the foundation plate210and the frame230. The watertight seal is necessary because deionized water is often used as the confinement layer.

The frame230further comprises a plurality of pin holes240for receiving pins. With the frame230in the first position, at least one of the foundation plate pin holes222,224corresponds to at least one of the frame pin holes240. When the frame230is placed in the second position, different foundation plate pin holes222,224correspond to different frame pin holes240. In this way, a first set of pin holes222are only used when the frame is in the first position, and a second set of pin holes224are only used in the second position. This allows an operator to easily identify what position the frame is in. At least one pin is placed through at least one pin hole to properly align and hold the frame230in either the first or second position.

One example method using the production apparatus200can comprise first bolting the foundation plate210onto a laser table. The golf club head is secured to the foundation plate210. The frame230is aligned over the foundation plate210and the club head strikeface. The frame230is aligned in a first position with the foundation plate210. The frame230is clamped down onto the foundation plate210and the strikeface. A plurality of TEM grids (acting as the mask layer) are inserted into the plurality of apertures238of the frame230. A carbon powder or graphene powder (acting as an absorptive layer) is tamped into the plurality of apertures238to cover the TEM grids. The plurality of apertures238is further filled with a deionized water (acting as a confinement layer). A Nd-YAG laser is shot through each aperture of the plurality of apertures238to peen (or forge) the portions of the strikeface underneath each aperture.

The frame230is removed and cleaned. The frame230is placed onto the foundation plate210in the second position. The process of preparing and treating the face is repeated at the second location. Because the frame230has been shifted, new areas of the face are treated. In this way, a majority of the strikeface surface area can be treated in a time-efficient and cost-effective manner.

EXAMPLES

Example 1—Robot Test

A comparison was done between an exemplary golf club head having a textured strikeface front surface and a control golf club head having a strikeface front surface lacking said texture. The exemplary golf club head was a wedge-type golf club head, having a loft angle of 58 degrees. The exemplary golf club head comprised a strikeface and a body, similar to golf club head10, describe above. The exemplary golf club head was formed from 8620 alloy steel. The strikeface comprised a front surface having a plurality of indentions.

In the exemplary club head, the indentions on the strikeface front surface were square-shaped. Each indention of the plurality of indentions had a footprint area of approximately 1369 μm2(0.00000225 in2), a width of approximately 37 μm (0.0015 inch), a height of approximately 37 μm (0.0015 inch), and a maximum depth of approximately 600 μm (0.0232 inch). The plurality of indentions was organized into rows of indentions. The rows were oriented horizontally (heel-to-toe) when the golf club head was at address position. Each indention was spaced apart from each adjacent indention by a separation distance of approximately 37 μm (0.0015 inch). The plurality of indentions was formed into the strikeface of the exemplary golf club head using a LSSP process. The control golf club head was identical to the exemplary golf club head, except the control lacked a plurality of indentions on the strikeface front surface.

The plurality of indentions was applied in groups, where each group of indentions was organized in a circle with a 2 mm diameter (similar to the pocket regions62, described above). Each group of indentions was made with a single laser pulse, which had a duration of 7 ns, and an energy density of 1 GW/cm{circumflex over ( )}2. The groups of indentions were placed adjacent to one another, with approximately 0.1 mm distance between the edge of each 2 mm diameter circle in the heel-to-toe direction. Overlapping groups of indentions is not possible. Therefore, achieving a minimum separation distance between groups is critical to covering the surface with the LSSP texture/indentions.

Three performance parameters were tested: launch angle, ball speed, and ball spin. Each parameter was tested under both dry and wet conditions. In the wet condition test, both the ball and the club head were exposed to moisture prior to each test shot. The comparison was done using a robot, which was programmed to swing the golf club in an identical manner for each shot. Fifteen shots were taken under dry conditions and fifteen shots were taken under wet conditions. The data is presented below as averages of these fifteen shot sets. A statistical area corresponding to where the shots settled was also measured for both clubs, to illustrate each test club's potential shot precision.

As illustrated in the graph ofFIG. 15, under dry conditions, the launch angle of the exemplary club head was roughly comparable to the launch angle of the control club head. In this test, the launch angle was approximately 31.5 degrees for the control and approximately 31.4 degrees for the exemplary club head, with error bars of roughly 0.2 degrees. However, under wet conditions, the launch angle of the exemplary club head was approximately 2.2 degrees less than the launch angle of the control club head, with error bars of approximately 0.7 degrees. The launch angle was approximately 33.1 degrees for the control and approximately 30.9 for the exemplary club head. The lower launch angle of the exemplary club head can cause the ball to travel a more precise distance. Since wind intensity increases at higher distances above the ground, when the launch angle is lower, the golf ball will spend less time in elevated wind conditions. As seen in the aforementioned data, the exemplary club head exhibited a wet condition launch angle close to its dry condition launch angle. This performance similarity across conditions creates more consistency for the golfer, allowing him or her to better predict shot performance.

As illustrated in the graph ofFIG. 16, under dry conditions, the spin rate imparted to a golf ball by the exemplary club head was comparable to the spin rate imparted by the control club head. In this test, the average spin rates under dry conditions were approximately 10,222 rpm for the control and 10,206 rpm for the exemplary club head, with error bars between 100 to 300 rpm. Under wet conditions, the spin rate imparted by the exemplary club head was significantly higher than the spin rate imparted by the control club head. Under wet conditions, the exemplary club head imparted an average spin rate of approximately 10,578 rpm, with an error bar of approximately 500 rpm. Under wet conditions, the control club head imparted an average spin rate of approximately 9,316 rpm. Therefore, under wet conditions, the exemplary club head imparted a spin rate that was approximately 13.5% faster than the spin rate imparted by the control club head. This faster spin rate helps the golf ball to settle close to where the shot first impacts the ground. Reducing the spin rate can reduce rolling of the ball after it lands, which improves shot accuracy.

The spin rate data also shows that the exemplary club head has a more consistent spin rate across dry and wet conditions than the control club head. For the control club head, the average spin differs by approximately 906 rpm between dry and wet conditions. For the exemplary club head, the average spin rate differs by approximately 372 rpm between dry and wet conditions. Therefore, since the average spin rate differs less between dry and wet conditions for the exemplary club head, a golfer will better be able to predict shot performance with the exemplary club head.

As illustrated in the graph ofFIG. 17, the ball speed imparted by the exemplary club head was slightly lower under dry conditions and slightly higher under wet conditions, compared to the control club head. Therefore, the ball speed was more consistent across conditions. Under dry conditions, the ball speed imparted by the control club head was approximately 76.2 mph, with an error bar of approximately 0.3 mph. The ball speed imparted by the exemplary club head, under dry conditions, was approximately 75.8 mph, with an error bar of approximately 0.3 mph. Under wet conditions, the ball speed of the exemplary club head was approximately 75.1 mph, with an error bar of approximately 0.4 mph. The ball speed of the control club head was approximately 74.8 mph, with an error bar of approximately 0.6 mph. This data shows that the texture on the strikeface of the exemplary club head does not greatly affect ball speed either negatively or positively, when the overall performance of the club head is considered.

The plot ofFIG. 18shows a statistical area determined by the location at which the test shots landed. Shots taken with the exemplary club head were about more than twice as precise as shots taken with the control club head. The statistical area for the control club head was approximately 18 square yards, whereas the statistical area for the exemplary club head was approximately 7 square yards. Shots taken with the control club head carried from approximately 85 yards to 92 yards, a variance of approximately 7 yards downline. Shots taken with the exemplary club head carried from approximately 87 yards to 90 yards, a variance of approximately 3 yards downline. Additionally, the exemplary club head also exhibited less offline (left or right) variance than the control club head.

This comparison test further showed that the coefficient of friction between the strikeface front surface and a urethane golf ball increased by approximately 40-45%, under wet conditions, when the strikeface was textured by an LSSP process. In other words, the exemplary club head strikeface showed a coefficient of friction that was 40-45% higher than the coefficient of friction of the control club head strikeface.

In summary, the exemplary club head exhibited a lower launch angle, a higher spin rate, and a greater golf ball-to-strikeface coefficient of friction than the control club head. These factors give a golfer greater precision in his or her shots. The test further verified this increase in shot precision through statistical area plots.

Example 2—Prospective Player Test

A prospective player test comparison will be done between an exemplary golf club head having a textured strikeface front surface and a control golf club head having a strikeface front surface lacking said texture. For this comparison test, fifteen to twenty golfers will take shots with the test golf clubs. The exemplary golf club head will be a wedge-type golf club head identical to the exemplary golf club head of Example 1, above. In short, the exemplary golf club head will comprise a strikeface front surface having a plurality of square-shaped indentions, each with a footprint area of approximately 1369 μm2(0.00000225 in2) and a maximum depth of approximately 600 μm (0.0232 inch). The plurality of indentions will be formed through an LSSP process. The control golf club head will be identical to the exemplary golf club head, except the control will lack a plurality of indentions on the strikeface front surface.

Three performance parameters will be tested: launch angle, ball speed, and ball spin. Each parameter will be tested under real-world, wet conditions. The shots will be taken from grass turf that is maintained to match fairway conditions on a golf course. Each golfer will take a total of ten shots with each golf club, alternating every five shots between the golf club with the exemplary head and the golf club with the control head. A statistical area corresponding to where the shots settle will also be measured for both clubs, to illustrate each test club's potential shot precision. A coefficient of friction between the strikefaces and a urethane golf ball will be calculated from the launch angle and ball spin results.

It is expected that the launch angle of the exemplary club head will be approximately 2 degrees less than the launch angle of the control club head. The lower launch angle of the exemplary club head is expected to cause the ball to travel a more precise distance.

It is expected that the spin rate imparted by the exemplary club head will be significantly higher than the spin rate imparted by the control club head. The exemplary club head is expected to impart an average spin rate that is approximately 1,000 rpm higher than the control club head. The exemplary club head is expected to impart a spin rate that is approximately 10-20% faster than the spin rate imparted by the control club head. This faster spin rate will help the golf ball to settle close to where the shot first impacts the ground, improving shot accuracy.

It is expected that the ball speed will be between 70 and 80 mph. The ball speed imparted by the exemplary club head, is expected to be approximately 0.5 mph higher than the ball speed imparted by the control club head. A statistical area will be determined by the location at which the test shots land. Shots taken with the exemplary club head are expected to be more than twice as precise as shots taken with the control club head. Additionally, the exemplary club head is expected to exhibit less offline (left or right) variance than the control club head.

Furthermore, the exemplary club head strikeface is expected to show a coefficient of friction (with respect to a urethan covered golf ball) that is 40-45% higher than the coefficient of friction of the control club head strikeface. In summary, the exemplary club head is expected to exhibit a lower launch angle, a higher spin rate, and a greater golf ball-to-strikeface coefficient of friction than the control club head. This test is further expected to verify that texturing the strikeface using LSSP increases shot precision.

Example 3—Laser Intensity to Indention Depth

A prospective experiment will be done to show the correlation between laser intensity and indention depth. Table I, below, shows some expected maximum indention depths of the certain laser intensities.

It is expected that treating a strikeface with an LSSP process that uses a laser intensity of approximately 0.484 GW/cm2will result in a maximum indention depth of approximately 0.2 μm. It is expected that treating a strikeface with an LSSP process that uses a laser intensity of approximately 0.554 GW/cm2will result in a maximum indention depth of approximately 0.5 μm. It is expected that treating a strikeface with an LSSP process that uses a laser intensity of approximately 0.778 GW/cm2will result in a maximum indention depth of approximately 0.8 μm. It is expected that treating a strikeface with an LSSP process that uses a laser intensity of approximately 0.890 GW/cm2will result in a maximum indention depth of approximately 0.9 μm. It is expected that treating a strikeface with an LSSP process that uses a laser intensity of approximately 575 GW/cm2will result in a maximum indention depth of approximately 4.9 μm. It is expected that treating a strikeface with an LSSP process that uses a laser intensity of approximately 1920 GW/cm2will result in a maximum indention depth of approximately 15 μm. As outlined by these prospective results, this experiment is expected to show that increasing the laser intensity will also increase the maximum indention depth.

The results of this prospective experiment are expected to resemble the results of an experiment recorded in the publication Mao, Bo & Siddaiah, Arpith & Menezes, Pradeep & Liao, Yiliang. (2018). ‘Surface Texturing by indirect laser shock surface patterning for manipulated friction coefficient,’Journal of Materials Processing Tech. vol. 257 (2018) pp. 227-233). The Mao, et al. publication teaches that a higher laser intensity can result in a greater indention depth. In the Mao et al. experiment, as the laser intensity increases from approximately 0.5 GW/cm2to approximately 0.9 GW/cm2, the indention depth increases from approximately 0.2 μm to approximately 0.9 μm.

As the rules to golf may change from time to time (e.g., new regulations may be adopted or old rules may be eliminated or modified by golf standard organizations and/or governing bodies), golf equipment related to the methods, apparatus, and/or articles of manufacture described herein may be conforming or non-conforming to the rules of golf at any particular time. Accordingly, golf equipment related to the methods, apparatus, and/or articles of manufacture described herein may be advertised, offered for sale, and/or sold as conforming or non-conforming golf equipment. The methods, apparatus, and/or articles of manufacture described herein are not limited in this regard.

Although a particular order of actions is described above, these actions may be performed in other temporal sequences. For example, two or more actions described above may be performed sequentially, concurrently, or simultaneously. Alternatively, two or more actions may be performed in reversed order. Further, one or more actions described above may not be performed at all. The apparatus, methods, and articles of manufacture described herein are not limited in this regard.

Clause 1: A golf club head comprising: a body comprising a heel end and a toe end; a strikeface comprising a geometric center; wherein: the strikeface comprises a front surface; the front surface comprises a plurality of indentions; each indention of the plurality of indentions comprises a center point, one or more sidewalls, and a bottom surface; each indention has a footprint area measured as the area bounded by the sidewalls within a plane coincident with the front surface; the footprint area is between 0.01 μm2and 250,000 μm2; each indention has a maximum depth measured orthogonal to the front surface, from the bottom surface to a plane coincident with the front surface; the maximum depth is between 0.1 μm to 15 μm; each indention has a width measured in a heel-to-toe direction through the center point of the indention; and the width is between 0.1 μm and 500 μm.

Clause 2: The golf club head of clause 1, wherein: each indention has a height measured in a sole-to-top rail direction through the center point of the indention; and the height is between 0.1 μm and 500 μm.

Clause 3. The golf club head of clause 1, wherein a coefficient of friction between the front surface and a urethane covered golf ball is between 0.05 and 0.95.

Clause 4: The golf club head of clause 1, wherein each indention's footprint area has a shape selected from the group consisting of: a square shape, a triangular shape, a rectangular shape, a circular shape, and a hexagonal shape.

Clause 5: The golf club head of clause 1, wherein the one or more sidewalls comprises a number of sidewalls selected from the group consisting of: one sidewall, two sidewalls, three sidewalls, four sidewalls, five sidewalls, six sidewalls, seven sidewalls, eight sidewalls, nine sidewalls, and ten sidewalls.

Clause 6: The golf club head of clause 1, wherein the plurality of indentions covers between 30% to 60% of the front surface.

Clause 7: The golf club head of clause 1, wherein the plurality of indentions covers between 60% to 100% of the front surface.

Clause 8: The golf club head of clause 1, wherein the footprint area is between 500 μm2and 100,000 μm2.

Clause 9: The golf club head of clause 1, wherein every indention of the plurality of indentions is spaced apart from adjacent indentions by a separation distance of between 1 μm and 250 μm (approximately 3.9×10−5 inch and approximately 0.0098 inch).

Clause 10: The golf club head of claim1, wherein the plurality of indentions increase golf ball spin rate by 5% to 30%, under wet conditions.

Clause 11: The golf club head of claim1, wherein the plurality of indentions increase launch angle by 1-3 degrees, under wet conditions.

Clause 12: A golf club head comprising: a body comprising a heel end and a toe end; a strikeface comprising a geometric center; wherein: the strikeface comprises a front surface; the front surface comprises an indention array, having multiple indention rows aligned parallel to an array axis; each indention comprises a center point, one or more sidewalls, and a bottom surface; each indention has a footprint area measured as the area bounded by the sidewalls within a plane coincident with the front surface; the footprint area is between 0.01 μm2and 250,000 μm2; each indention has a maximum depth measured orthogonal to the front surface, from the bottom surface to a plane coincident with the front surface; the maximum depth is between 0.1 μm to 15 μm; each indention has a width measured parallel to the array axis through the center point of the indention; and the width is between 0.1 μm and 500 μm.

Clause 13: The golf club head of clause 12, wherein: the golf club head further comprises a horizontal reference axis, which extends through the geometric center of the strikeface from the heel end to the toe end; and the indention array is angled such that the array axis intersects the horizontal reference axis at an angle of plus or minus 0 to 90 degrees.

Clause 14: The golf club head of clause 13, wherein: the indention array is angled such that the array axis intersects the horizontal reference axis at an angle selected from the group consisting of: plus or minus 10 degrees, plus or minus 20 degrees, plus or minus 30 degrees, plus or minus 40 degrees, plus or minus 45 degrees, plus or minus 50 degrees, plus or minus 60 degrees, plus or minus 70 degrees, plus or minus 80 degrees, and 90 degrees.

Clause 15: The golf club head of clause 12, wherein: the golf club head further comprises a horizontal reference axis, a low region, and a high region; the horizontal reference axis extends through the geometric center of the strikeface from the heel end to the toe end; the low region is below the horizontal reference axis; the high region is above the horizontal reference axis; and a majority of the indention array is located within the low region.

Clause 16: The golf club head of clause 12, wherein a coefficient of friction between the front surface and a urethane covered golf ball is between 0.05 and 0.95.

Clause 17: The golf club head of clause 12, wherein: the indention array comprises an array length, measured in a direction from the heel end to the toe end; and the array length is between 1.5 inch and 2.5 inches.

Clause 18: A golf club head comprising: a body; a strikeface; wherein: the strikeface comprises a front surface; the front surface comprises an indention array, having multiple indention rows aligned parallel to an array axis; each indention comprises a center point, one or more sidewalls, and a bottom surface; each indention has a footprint area measured as the area bounded by the sidewalls within a plane coincident with the front surface; the footprint area is between 0.01 μm2and 250,000 μm2; each indention has a maximum depth measured orthogonal to the front surface, from the bottom surface to a plane coincident with the front surface; each indention has a width measured parallel to the array axis through the center point of the indention; each indention comprises an aspect ratio, which equals the maximum depth over the width; the aspect ratio is between 3 and 150.

Clause 19: The golf club head of clause 18, wherein the aspect ratio is between 75 and 125.

Clause 20: The golf club head of clause 18, wherein the aspect ratio is between 50 and 100.