Patent Application
20240157204
This disclosure relates generally to a golf club head and a methods for heat treating the outer surface of the golf club head in order to increase the surface hardness and corrosion resistance of the golf club head outer surface. The method described herein can be related to golf equipment, and more particularly, to materials for faceplates and golf club bodies, and methods to manufacture and heat treat.
The golf club head can be manipulated to change the physical and mechanical characteristics of the club head. Golf club heads undergo several manufacturing processes to arrive at a final product having desired physical specifications. For example, after the fabrication of the golf club head by casting or forging, a variety of surface treatments can be applied to obtain the desired mechanical and physical properties. Subsequent to surface treatment, the loft angle and/or lie angle of the golf club head can be manipulated.
Both the loft angle and lie angle directly affect the club head's ability to accurately direct the golf ball down the desired target line, at the desired launch angle. The loft angle (also referred to as “the loft”) of the golf club head refers to the angle formed between the club face and the ground plane when the golf club is held at an address position. The loft affects the trajectory and spin rate of the golf ball. The lie angle (also referred to as “the lie”) of the golf club head refers to the angle formed between the shaft and the ground plane when the golf club is held at an address position. Without the proper lie angle, the player will lose their ability to consistently and accurately advance the golf ball down the desired target line at the desired launch angle. Therefore, it is necessary to adjust the loft and lie angle after the club head is formed to ensure the desired loft and lie angle are achieved.
During such bending operations, the club head may develop cosmetic flaws such as stress marks and/or structural failure. More specifically, tension forces may cause cracks to form on the outer surface of the club head. Conventional surface treatment methods, such as known quench-polish-quench processes, results in harnesses and material structures that are prone to surface cracks during bending or other physical manipulation during manufacturing. Therefore, there is a need in the art for a manufacturing process that provides the desired surface hardness of a golf club head while minimizing the presence of surface face cracks on the hosel.
To facilitate further description of the embodiments, the following drawings are provided in which:
For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements.
Described herein is a golf club head comprising uniform nitride and oxide layers. The formation of a flat and uniform nitride layer that binds to the actual metal of the golf club head greatly improves bonding with the oxide layer, as well as helping to form oxide layers with more uniform thicknesses. The improved bonding and uniformity reduce porosity caused by agitation of the applied oxide layers. While some porosity, associated with porosity grades 1-3, near the surface is anticipated and considered acceptable; porosity deeper below the surface is undesirable and mitigated by the QPQ method described herein. Specifically, porosity, associated with porosity grades 4-5 and seen in traditional QPQ methods, below the surface promotes cracks that are highly visible to the user and reduce stability of the material, thereby increasing risk of deformation or failure. Therefore, the uniformity of the layers, which generates a porosity grade of 3 or better thereby limiting both the formation and growth of cracks, resulting in fewer cracks that are smaller and therefore less visible to the user. These uniform layers can be achieved by an improved quench-polish-quench method, as discussed in detail below.
The terms “first,” “second,” “third,” “fourth,” and the like as used herein, for distinguish between similar elements and do not necessarily describe a particular sequential or chronological order. It is to be understood that the terms used are interchangeable under appropriate circumstances such that the embodiments described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “include,” and “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, device, or apparatus that comprises a list of elements is not necessarily limited to those elements but may include other elements not expressly listed or inherent to such process, method, system, article, device, or apparatus.
The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like as used herein, are for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.
The terms “couple,” “coupled,” “couples,” “coupling,” and the like, as used herein, should be broadly understood and refer to connecting two or more elements or signals, electrically, mechanically and/or otherwise.
The term “composition,” as used herein, is defined as the kinds and relative count of elements in a material. For alloyed materials, the composition describes the weight percent of each alloying element within the material.
The term “tensile strength,” as used herein, is defined as the maximum strength under a tensile, or pulling load that a material can absorb without failure. Here, failure is experienced when fracture, snapping, or breakage occurs.
The term “brittleness,” as used herein, is defined as the failure by sudden fracture, without plastic deformation. Brittleness is further defined as the absence of ductility.
The “modulus of elasticity,” or “Young's Modulus,” as used herein, is the ratio of stress to strain and is the slope (E) of the stress-strain curve in the elastic region. The modulus is used to describe a material's stiffness.
The term “yield strength” or “proportional limit,” as used herein, is defined as the point on the stress strain curve wherein the material is loaded in tension to the point of permanent, or plastic deformation, such that the deformation remains when the load has been removed.
The term “elongation” or “minimum elongation,” as used herein, is a measure of the amount of stretch or elongation the material can withstand before it starts to permanently deform.
The term “quench,” as used herein, is defined as the process of rapidly cooling a metal to obtain certain material properties. The rapid cooling can be achieved by applying a quench media for a predetermined exposure time, and at a predetermined temperature. The quench media can include caustics, oils, molten salt, and gas. The cooling rate and quenching media determine the mechanical properties of the metal directly after quenching.
The term “quench polish quench,” as used herein, is defined as a thermochemical process in which nitrogen and carbon are simultaneously diffused into the material surface in the presence of a salt bath.
The term “aging,” as used herein, is defined as a form heat treatment, wherein the material is allowed to slowly cool to room temperature, in order to increase strength.
The term “pit furnace,” as used herein, defines a type of furnace used for metallurgical processes, which typically require lower temperatures. The pit furnace described herein can comprise a cylindrical shape and can further comprise an opening at the top of the furnace through which a holding fixture can be inserted. The pit furnace manipulates the atmosphere in which the golf clubhead is immersed. This can include, but is not limited, to manipulating the temperature and pressure.
The term “metallurgical processes,” as used herein, defines a process for extracting metals into purer forms.
The term “nitriding,” as used herein, is defined as a diffusion-related surface treatment with the ability to increase surface hardness. Nitriding can further enhance the following mechanical properties: resistance to wear, minimize deformation, resistance to tempering, improve fatigue life, and reduction in notch sensitivity.
The term “compound layer,” as used herein, is defined as the coating formed atop the material surface, directly resultant from the QPQ process. The compound layer can comprise multiple layers—including all applicable nitride and oxide layers formed by the QPQ process.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” and “having,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. All weight percent (wt %) numbers described below are a total weight percent.
The general terms used to describe the material properties associated with the disclosed material are provided herein. These definitions are regarded as the industry standard and are provided by the professional society of material scientists and material engineers, ASM International.
The term “geometric centerpoint,” or “geometric center” of the strike face, as used herein, can refer to a geometric centerpoint of the strikeface perimeter, and at a midpoint of the face height of the strike face. In the same or other examples, the geometric centerpoint also can be centered with respect to an engineered impact zone, which can be defined by a region of grooves on the strike face. As another approach, the geometric centerpoint of the strikeface can be located in accordance with the definition of a golf governing body such as the United States Golf Association (USGA).
The term “ground plane,” as used herein, can refer to a reference plane associated with the surface on which a golf ball is placed. The ground plane can be a horizontal plane tangent to the sole at an address position.
The term “loft plane,” as used herein, can refer to a reference plane that is tangent to the geometric centerpoint of the strike face.
The term “loft angle,” as used herein, can refer to an angle measured between the loft plane and the XY plane (defined below).
The term “face height,” as used herein, can refer to a distance measured parallel to loft plane between the top end of the strikeface perimeter and a bottom end of the strikeface perimeter.
The term “lie angle,” as used herein, can refer to an angle between a hosel axis, extending through the hosel, and the ground plane. The lie angle is measured from the front view.
The “geometric center height” of the fairway-type golf club head, as used herein, is a height measured perpendicular from the ground plane to the geometric centerpoint of the golf club head.
The “leading edge” of the club head, as used herein, can be identified as the most sole-ward portion of the strikeface perimeter.
Described herein are golf club heads and various methods for treating a golf club head, in a series of steps completed post-fabrication, to strengthen the metallic golf club head outer surface (hereafter alternately referred to as “the outer surface”) by providing a more uniform black coating or finish. The uniform finish greatly improves bonding ability of layers within the coating, as well as uniformity, resiliency, and appearance. The improved bonding and uniformity prevent the occurrence of porosity caused by agitation of the black finish. As mentioned above, while porosity near the surface is anticipated and considered acceptable, porosity beyond the region nearest the surface is undesirable, as porosity beyond the surface results in undesirable deep cracks that are highly visible to the user and reduce stability of the material, increasing risk of deformation or failure. These deep cracks extend downward into the second oxide layer and primary nitride layer when the nitride layer, first oxide layer, and second oxide layer are not uniform. Therefore, the uniformity of the finish can limit both the formation and growth of the cracks, ensuring less cracks and less cracks that are valuable to the user. This uniform coating can be achieved by an improved quench-polish-quench (hereafter referred to as “QPQ”) method, as discussed in detail below.
The QPQ method can create a more uniform surface hardness and improve corrosion resistance of the outer surface by applying a QPQ finish to the golf club head 100 after it is formed. The improved uniformity in surface hardness and increase in corrosion resistance can be attributed to a plurality of blasting steps used during the QPQ process. The plurality of blasting steps forms the QPQ finish with layers having more uniform thicknesses. The QPQ finish can include a nitride layer 230, a first oxide layer 120, and a second oxide layer 122. The method described above can result in a golf club head with a QPQ finish having uniform nitride and oxide layers. The plurality of blasting steps forms a more uniform nitride layer, followed by a more uniform first oxide layer 120, followed by a more uniform second oxide layer 122 on the outer surface of the golf club head 100, as shown in
As mentioned above, the aforementioned QPQ method can be applied to a golf club 100. The golf club can comprise a golf club head 100, a shaft, and a grip. The golf club head 100 can comprise a body having a strikeface 104, a top rail 110 opposite a sole 106, a toe opposite a heel, a hosel 102 coupled to the club body and having a first end proximate the heel and a second end opposite the first end. The golf club head 100 can further comprise an outer surface. The QPQ method can be applied to a portion of the golf club head 100 or the entire golf club head 100. The golf club head 100 as described herein, being treated with the QPQ method, increases the degree to which the loft and lie may be adjusted while reducing surface deformation and increasing durability.
Surface hardness and corrosion resistance are improved by applying the following QPQ method during the manufacturing process. The QPQ method can include the steps described below and illustrated in
More specifically, the first step can comprise aging the golf club head 100 in the nitriding salt bath (hereafter alternate refer to as “the salt bath) within the first furnace for a predetermined amount of time (hereafter referred to as “the aging time”) at a predetermined temperature (hereafter referred to as “the aging temperature”). The salt bath can comprise a chemical composition, such as NaCNO, KCNO, Na2CO3, K2CO3, KCI, Li2CO3, and Na2SO4. The salt bath can include a combination of compounds, wherein the amount of each compound used in the salt bath is characterized by a percentage indicating a proportion of the salt bath attributed to that compound. The percentage of each of the compounds can affect how the golf club head outer surface reacts with the salt bath, and more specifically can influence how the nitride layer 230, the first oxide layer 120, and the second oxide layer 122 are formed.
In some embodiments, the salt bath includes 30-60% NaCNO. In some embodiments, the percentage of NaCNO can range from 30% to 35%, 35% to 40%, 40% to 45%, 45% to 50%, 50% to 55%, or 55% to 60%. In some embodiments, the percentage of NaCNO can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59% and 60%. In one embodiment, the percentage of NaCNO ranges from 35% to 55%.
In some embodiments, the salt bath includes 0.01% to 25% KCNO. In some embodiments, the percentage of KCNO can range from 0.01% to 5%, 5% to 10%, 10% to 15%, 15% to 20%, or 20% to 25%. In some embodiments, the percentage of KCNO can be 0.01%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 21%, 22%, 23%, 24% or 25%. In one embodiment, the percentage of KCNO ranges from 0% to 20%. In some embodiments, the percentage of KCNO in the salt bath can be less than 5%, less than 10%, less than 15%, less than 20%, or less than 25%.
In some embodiments, the salt bath includes 3% to 13% Na2CO3. In some embodiments, the percentage of Na2CO3 can range from 3% to 5%, 5% to 7%, 7% to 9%, 9% to 11%, or 11% to 13%. In some embodiments, the percentage of Na2CO3 can be 3%. 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12% or 13%. In one embodiment, the percentage of Na2CO3 ranges from 5% to 10%.
In some embodiments, the salt bath includes 15% to 40% K2CO3. In some embodiments, the percentage of K2CO3 can range from 15% to 20%, 20% to 25%, 25% to 30%, 30% to 35%, or 35% to 40%. In some embodiments, the percentage of K2CO3 can be 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%. In one embodiment, the percentage of K2CO3 ranges from 20% to 35%.
In some embodiments, the salt bath includes 0.01% to 20% KCI. In some embodiments, the percentage of KCI can range from 0.01% to 5%, 5% to 10%, 10% to 15%, or 15% to 20%. In some embodiments, the percentage of KCI can be 0.01%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%. In some embodiments, the percentage of KCI in the salt bath can be less than 5%, less than 10%, less than 15%, or less than 20%. In one embodiment, the percentage of KCI ranges from 0.01% to 15%.
In some embodiments, the salt bath includes 0.01% to 15% Li2CO3. In some embodiments, the percentage of Li2CO3 can range from 0.01% to 5%, 5% to 10%, or 10% to 15%. In some embodiments, the percentage of Li2CO3 can be 0.01%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%. In some embodiments, the percentage of Li2CO3 in the salt bath can be less than 5%, less than 10%, or less than 15%. In one embodiment, the percentage of Li2CO3 ranges from 0.01% to 10%.
In some embodiments, the salt bath includes 0.01% to 5% Na2SO4. In some embodiments, the percentage of Na2SO4 can range from 0.01% to 1%, 1% to 2%, 2% to 3%, 3% to 4%, or 4% to 5%. In some embodiments, the percentage of Na2SO4 can be 0.01%, 1%, 2%, 3%, 4% or 5%. In some embodiments, the percentage of Na2SO4 in the salt bath can be less than 1%, less than 2%, less than 3%, less than 4%, or less than 5%. In one embodiment, the percentage of Na2SO4 ranges from 0% to 2%. As discussed above, the percentage of the compounds can affect how the surface of the outer surface reacts with the salt bath. More specifically, the percentages of the compounds can affect the formation of the nitride layer 230 and first oxide layer 120, affecting the surface hardness and corrosion resistance of the outer surface.
As discussed above, the salt bath can be aged by heating the salt bath up to the aging temperature for the aging time. The aging time can be between 5.00 hours and 7.00 hours. The aging time can be between 5.00 hours and 5.25 hours, 5.25 hours and 5.50 hours, 5.50 hours and 5.75 hours, 5.75 hours and 6.00 hours, 6.00 hours and 6.25 hours, 6.25 hours and 6.50 hours, 6.50 hours and 6.75 hours, or 6.75 hours and 7.00 hours. In one embodiment, the aging time is 6.00 hours.
The aging temperature can be between 525° C. and 605° C. The aging temperature can be between 525° C. and 535° C., 535° C. and 545° C., 545° C. and 555° C., 555° C. and 565° C., 565° C. and 575° C., 575° C. and 585° C., 585° C. and 595° C., or 595° C. and 605° C. The aging temperature can be 525° C., 526° C., 527° C., 528° C., 529° C., 530° C., 531° C., 532° C., 533° C., 534° C., 535° C., 536° C., 537° C., 538° C., 539° C., 540° C., 541° C., 542° C., 543° C., 544° C., 545° C., 546° C., 547° C., 548° C., 549° C., 550° C., 551° C., 552° C., 553° C., 554° C., 555° C., 556° C., 557° C., 558° C., 559° C., 560° C., 561° C., 562° C., 563° C., 564° C., 565° C., 566° C., 567° C., 568° C., 569° C., 570° C., 571° C., 572° C., 573° C., 574° C., 575° C., 576° C., 577° C., 578° C., 579° C., 580° C., 581° C., 582° C., 583° C., 584° C., 585° C., 586° C., 587° C., 588° C., 589° C., 590° C., 591° C., 592° C., 593° C., 594° C., 595° C., 596° C., 597° C., 598° C., 599° C., 600° C., 601° C., 602° C., 603° C., 604° C. or 605° C. In one embodiment, the aging temperature is 565° C.
Aging the salt bath at the specified time and temperature ensures the CNO concentration is between 28% and 36%. In some embodiments, the CNO concentration is between 28% and 29%, 29% and 30%, 30% and 31%, 31% and 32%, 32% and 33%, 33% and 34%, or 35% and 36%. As shown in
The second step can include blasting the outer surface. This step can involve blasting the golf club with a medium selected from the group consisting of: glass beads, sand, water, aluminum oxide, silicon carbide, steel shot, and any other suitable form of grit. The grit size can be between #60 grit and #320 grit. The grit size can be between #60 grit and #80 grit, #80 grit and #100 grit, #100 grit and #120 grit, #120 grit and #140 grit, #140 grit and #160 grit, #160 grit and #180 grit, #180 grit and #200 grit, #200 grit and #220 grit, #220 grit and #240 grit, #240 grit and #260 grit, #260 grit and #280 grit, #280 grit and #300 grit, or #300 grit and #320 grit. In one embodiment, the medium can be glass beads comprising a #80 grit. In one embodiment, the medium can be glass beads comprising a #220 grit.
Further, the blasting can be performed at a pressure. The pressure can be between 1 and 5 kg/cm2. In some embodiments, the pressure can be between 1 kg/cm2 and 2 kg/cm2, 2 kg/cm2 and 3 kg/cm2, 3 kg/cm2 and 4 kg/cm2 or 4 kg/cm2 and 5 kg/cm2. The pressure can be 1 kg/cm2, 2 kg/cm2, 3 kg/cm2, 4 kg/cm2 or 5 kg/cm2. In one embodiment, the blasting is performed at a pressure of 2 kg/cm2. In some embodiments, the second step can involve first blasting the outer surface with first medium comprising a first grit size at a first pressure and then blasting the outer surface with a second medium comprising a second grit size at a second pressure. The blasting can ensure the outer surface is uniform by reducing localized areas of excess buildup of the outer layer. A uniform outer surface at this point in the process can allow for greater uniformity in the formation of the nitride layer 230 and the first oxide layer 120, which are subsequently grown from this surface in.
In some embodiments, the second step can further include loading the golf club head 100 into the holding fixture. In one exemplary embodiment, the holding fixture can consist of a tree fixture. The tree fixture can allow for the treatment of numerous golf club heads at any given time.
The third step can involve placing the holding fixture into a second heating furnace and heating the second furnace to a predetermined temperature for a predetermined amount of time. The time and temperature can be selected to ensure little to no moisture is left on or in the golf club head 100. The predetermined temperature can be between 325° C. and 375° C. In one embodiment the predetermined temperature may be between 325° C. and 330° C., 330° C. and 335° C., 335° C. and 340° C., 340° C. and 345° C., 345° C. and 350° C., 350° C. and 355° C., 355° C. and 360° C., 360° C. and 365° C., 365° C. and 370° C., or 370° C. and 375° C. In one example, the predetermined temperature may be 350° C. The predetermined time of heating can be between 25 minutes and 35 minutes. The predetermined time can be between 25 minutes and 26 minutes, 26 minutes and 27 minutes, 27 minutes and 28 minutes, 28 minutes and 29 minutes, 29 minutes and 30 minutes, 30 minutes and 31 minutes, 31 minutes and 32 minutes, 32 minutes and 33 minutes, 33 minutes and 34 minutes, or 34 minutes and 35 minutes. The time and temperature are selected to allow the atmosphere of the pit furnace to reach an equilibrium. This step can ensure little to no moisture is on or in the golf club head 100, improving the bonding ability of the second oxide layer 122, as discussed in depth below.
The fourth step can involve moving the holding fixture from the second furnace to the first furnace, submerging the holding fixture in the salt bath, and allowing the holding fixture to remain in the first furnace for a predetermined amount of time. The predetermined time can be long enough to allow for the formation of a nitride layer 230 on the golf club head outer surface.
The predetermined temperature, used in the fourth step, can be between 500° C. and 650° C. In one embodiment, the predetermined temperature may be between 500° C. and 525° C., 525° C. and 550° C., 550° C. and 575° C., 575° C. and 600° C., 600° C. and 625° C., or 625° C. and 650° C. In one example, the predetermined temperature may be 580° C. The predetermined time, used in the fourth step, can be between 35 minutes and 55 minutes. In some embodiments, the predetermined time may be between 35 minutes and 40 minutes, 40 minutes and 45 minutes, 45 minutes and 50 minutes, or 50 minutes and 55 minutes. The time and temperature are selected to allow for the complete formation of the nitride layer 230.
The nitride layer 230 forms from a chemical reaction between the salt bath and the outer surface. The chemical equation can be seen in
The nitride layer 230 can comprise both mechanical and physical properties that can affect the durability and performance of the finished golf club head 100. Such mechanical properties can include, but are not limited to, the hardness and the uniformity of the nitride layer 230 (hereafter alternately referred to as “the nitride uniformity”). The uniformity can refer to the thickness of the layer being substantially the same throughout the layer. The uniformity can be quantified by being equal to the difference between a maximum nitride thickness and a minimum nitride thickness. Such physical properties can include but are not limited to a nitride thickness, the maximum nitride thickness, and the minimum nitride thickness.
The nitride thickness can be defined as the distance from the point where the nitride layer 230 meets the core 110 to the point where the nitride layer 230 meets the first oxide layer 120. The nitride thickness can be between 0.00025 inches and 0.00060 inches. The nitride thickness can be between 0.00025 inches and 0.00030 inches, 0.00030 inches and 0.00035 inches, 0.00035 inches and 0.00040 inches, 0.00040 inches and 0.00045 inches, 0.00045 inches and 0.00050 inches, 0.00050 inches and 0.00055 inches, 0.00055 inches and 0.00060 inches, or 0.00060 inches and 0.00065 inches. As discussed above, the nitride thickness can affect the durability and performance of the QPQ finish. More specifically, a nitride thickness that is too large can increase the force necessary to adjust the loft and lie. The increase in force could lead to overstressing the QPQ finish, increasing the cracking caused during the loft/lie adjustment process. Further, a nitride thickness that is too thin may not be sufficiently strong, and therefore can crack in response to forces applied during the loft/lie adjustment process. Additionally, QPQ finishes tend to be brittle finish, and therefore, as the nitride layer 230 increases in thickness, so does the possibility of larger cracks 108 and the ease at which these cracks 108 form.
The nitride layer 230 can further comprise a nitride maximum thickness and a nitride minimum thickness. The nitride maximum thickness can be defined as the largest distance from a point where the nitride layer 230 meets the core 110 to a point where the nitride layer 230 meets the first oxide layer 120. The nitride maximum thickness can be measured in a direction perpendicular to the nitride layer 230 at the point the measurement is taken. The nitride maximum thickness can be between 0.00025 inches and 0.00045 inches.
The nitride minimum thickness can be defined as the smallest distance from a point where the nitride layer 230 meets the core 110 to a point where the nitride layer 230 meets the first oxide layer 120. The nitride minimum thickness can be measured in a direction perpendicular to the nitride layer 230 at the point the measurement is taken. The nitride minimum thickness can be between 0.00045 inches and 0.00060 inches.
The nitride layer 230 can further comprise a nitride uniformity, herein defined as the ratio between the maximum thickness and the minimum thickness. The uniformity can be between 1.00 and 1.25. The uniformity can be between 1.00 and 1.05, 1.05 and 1.10, 1.10 and 1.15, 1.15 and 1.20, or 1.20 and 1.25. The uniformity can be less than 1.25, less than 1.20, less than 1.15, or less than 1.10. The closer the uniformity is to 1 the more uniform the nitride thickness is. The nitride uniformity can further ensure the uniformity of the first oxide layer 120 by providing the first oxide layer 120 with a consistent and uniform surface to grow from. Any uniformity or lack thereof of the nitride layer 230 can translate directly into the uniformity of the first oxide layer 120.
The fifth step can involve lowering the temperature of the furnace to a predetermined temperature for a predetermined about of time, to allow for the formation of a first oxide layer 120 on top of the nitride layer 230, as discussed above. The predetermined temperature can be between 345° C. and 415° C. In some embodiments, the predetermined temperature may be between 345° C. and 350° C., 350° C. and 355° C., 355° C. and 360° C., 360° C. and 365° C., 365° C. and 370° C., 370° C. and 375° C., 375° C. and 380° C., 380° C. and 385° C., 385° C. and 390° C., 390° C. and 395° C., 395° C. and 400° C., 400° C. and 405° C., or 405° C. and 410° C. The predetermined temperature can be 345° C., 346° C., 347° C., 348° C., 349° C., 350° C., 351° C., 352° C., 353° C., 354° C., 355° C., 356° C., 357° C., 358° C., 359° C., 360° C., 361° C., 362° C., 363° C., 364° C., 365° C., 366° C., 367° C., 368° C., 369° C., 370° C., 371° C., 372° C., 373° C., 374° C., 375° C., 376° C., 377° C., 378° C., 379° C., 380° C., 381° C., 382° C., 383° C., 384° C., 385° C., 386° C., 387° C., 388° C., 389° C., 390° C., 391° C., 392° C., 393° C., 394° C., 395° C., 396° C., 397° C., 398° C., 399° C., 400° C., 401° C., 402° C., 403° C., 404° C., 405° C., 406° C., 407° C., 408° C., 409° C., 410° C., 411° C., 412° C., 413° C., 414° C. or 415° C. In one embodiment, the predetermined temperature can be 410° C. In another embodiment, the predetermined temperature can be 350° C. The predetermined time can be between 25 minutes and 35 minutes. The predetermined time may be between 25 minutes and 26 minutes, 26 minutes and 27 minutes, 27 minutes and 28 minutes, 28 minutes and 29 minutes, 29 minutes and 30 minutes, 30 minutes and 31 minutes, 31 minutes and 32 minutes, 32 minutes and 33 minutes, 33 minutes and 34 minutes, or 34 minutes and 35 minutes. In one embodiment, the predetermined time is 30 minutes. The time and temperature are selected to completely form a first oxide layer 120. A chemical reaction can occur such that the first oxide layer 120 can form on the club head outer surface, on top of the nitride layer 230, as mentioned above. The associated chemical reaction can be seen in
The first oxide layer 120 can comprise both mechanical and physical properties that can affect the durability and performance of the finished golf club head 100. Such mechanical properties can include but are not limited to the hardness and uniformity of the first oxide layer 120. Such physical properties can include but are not limited to the first oxide maximum thickness, the first oxide minimum thickness, and the uniformity of the first oxide layer 120 (hereafter alternately referred to as “the first oxide uniformity”).
The first oxide thickness can be defined as the distance from a point where the first oxide layer 120 meets the nitride layer 230 to a point where the first oxide layer 120 meets the second oxide layer 122. The first oxide thickness can be between 0.000045 inches and 0.000115 inches. The first oxide thickness can be between 0.000045 inches and 0.000055 inches, 0.000055 inches and 0.000065 inches, 0.000065 inches and 0.000075 inches, 0.000075 inches and 0.000085 inches, 0.000085 inches and 0.000095 inches 0.000095 inches and 0.000105 inches, or 0.000105 inches and 0.000115 inches. The first oxide thickness can be less than 0.000115 inches, less than 0.000105, less than 0.000105 inches, less than 0.000095, less than 0.000085, less than 0.00075, or less than 0.000065.
The first oxide maximum thickness can be defined as the largest distance from the point where the first oxide layer 120 meets the nitride layer 230 to the point where the first oxide layer 120 meets the second oxide layer 122. The first oxide maximum thickness can be measured in a direction perpendicular to the nitride layer 230 at the point the measurement is taken. The first oxide maximum thickness can be between 0.000075 inches and 0.000115 inches.
The first oxide minimum thickness can be defined as the smallest distance from the point where the first oxide layer 120 meets the nitride layer 230 to the point where the first oxide layer 120 meets the second oxide layer 122. The first oxide minimum thickness can be measured in a direction perpendicular to the nitride layer 230 at the point the measurement is taken. The first oxide maximum thickness can be between 0.000050 inches and 0.000075 inches.
The first oxide uniformity can refer to the thickness of the layer being substantially the same throughout the layer. The first oxide uniformity can be quantified by being equal to the difference between the first oxide maximum thickness and the first oxide minimum thickness. The uniformity can be between 1.00 and 1.85. The uniformity can be between 1.00 and 1.15, 1.15 and 1.30, 1.30 and 1.45, 1.45 and 1.60, 1.60 and 1.65, 1.65 and 1.80, or 1.80 and 1.95. The uniformity can be less than 1.95, less than 1.80, less than 1.65, or less than 1.50. The closer the uniformity is to 1 the more uniform the first oxide thickness is.
The sixth step can involve removing the holding fixture from the first furnace and cooling the club head 100 to a predetermined temperature. In some embodiments, cooling can be accomplished by allowing the club head 100 to air cool. In other embodiments, the club head 100 can be cooled by partially or fully submerging the club head 100 in a medium. The medium can be a gas or a liquid. In one embodiment the medium is an inert gas. The predetermined temperature can be between 60° C. and 100° C. In some embodiments, the predetermined temperature can be between 60° C. and 65° C., 65° C. and 70° C., 70° C. and 75° C., 75° C. and 80° C., 80° C. and 85° C., 90° C. and 95° C., or 95° C. and 100° C.
The club head 100 can be cooled over a specified period of time. The period of time can range from 20 minutes to 40 minutes. In some embodiments, the cooling can be performed over a period of time ranging from 20 minutes to 25 minutes, 25 minutes to 30 minutes, 30 minutes to 35 minutes, or 35 minutes to 40 minutes. Once the club head 100 is cooled, the club head 100 can be rinsed with water and then unloaded from the holding fixture.
The seventh step can involve blasting the outer surface to ensure uniformity throughout the first oxide layer 120. This step can involve blasting the golf club with a medium selected from the group consisting of: glass beads, sand, aluminum oxide, silicon carbide, steel shot and any other suitable form of grit. The medium can further comprise a grit size. The grit size can be between #60 grit and #320 grit. The grit size can be between #60 grit and #80 grit, #80 grit and #100 grit, #100 grit and #120 grit, #120 grit and #140 grit, #140 grit and #160 grit, #160 grit and #180 grit, #180 grit and #200 grit, #200 grit and #220 grit, #220 grit and #240 grit, #240 grit and #260 grit, #260 grit and #280 grit, #280 grit and #300 grit, or #300 grit and #320 grit. In one exemplary embodiment, the medium can be glass beads comprising a #80 grit. In one exemplary embodiment, the medium can be glass beads comprising a #220 grit.
Further, the blasting can be performed at a specified pressure. The pressure can be between 1 and 5 kg/cm2. In some embodiments, the pressure can be between 1 kg/cm2 and 2 kg/cm2, 2 kg/cm2 and 3 kg/cm2, 3 kg/cm2 and 4 kg/cm2 or 4 kg/cm2 and 5 kg/cm2. In one exemplary embodiment, the blasting is performed at a pressure of 2.5 kg/cm2. In some embodiments, the eighth step can involve first blasting the outer surface with first medium comprising a first grit size at a first pressure and then blasting the outer surface with a second medium comprising a second grit size at a second pressure. In one exemplary embodiment, the eighth step can involve blasting the outer surface with #80 grit glass beads at a pressure of 2.5 kg/cm2 and then blasting the outer surface with #220 grit glass beads at a pressure of 2.5 kg/cm2. As discussed above, the blasting ensures the first oxide layer 120 is uniform. A uniform first oxide layer 120 can allow for greater uniformity in the formation of the second oxide layer 122, thereby ensuring uniform strength throughout the golf club head outer surface.
The seventh step can further involve visually inspecting the golf club head 100 to ensure uniformity. As discussed above, ensuring uniformity in this step can further ensure the formation of the second oxide layer 122 is more uniform, therefore ensuring uniform strength throughout the golf club head outer surface. Each layer (nitride, first oxide, and second oxide) can have this step to ensure uniformity (near 1) to ensure each work in conjunction with each other to mitigate crack migration.
In some embodiments, the seventh step can further involve loading the golf club head 100 into the holding fixture. In one exemplary embodiment, the holding fixture can consist of a tree fixture. As previously discussed, the tree fixture can all for the ability to treat numerous golf club heads at any given time.
The eighth step can involve placing the holding fixture into a second heating furnace and heating the second furnace to a predetermined temperature for a predetermined amount of time. The time and temperature can be selected to ensure no moisture is left on or in the golf club head 100. The predetermined temperature can be between 325° C. and 375° C. In one embodiment the predetermined temperature may be between 325° C. and 330° C., 330° C. and 335° C., 335° C. and 340° C., 340° C. and 345° C., 345° C. and 350° C., 350° C. and 355° C., 355° C. and 360° C., 360° C. and 365° C., 365° C. and 370° C., or 370° C. and 375° C. In one example, the predetermined temperature may be 350° C. The predetermined time can be between 25 minutes and 35 minutes. In one embodiment the predetermined time may be between 25 minutes and 26 minutes, 26 minutes and 27 minutes, 27 minutes and 28 minutes, 28 minutes and 29 minutes, 29 minutes and 30 minutes, 30 minutes and 31 minutes, 31 minutes and 32 minutes, 32 minutes and 33 minutes, 33 minutes and 34 minutes, or 34 minutes and 35 minutes. The time and temperature are selected to allow the atmosphere of the pit furnace to reach an equilibrium. This step can ensure little to no moisture is on or in the golf club head 100, improving the bonding ability of the second oxide layer 122, as discussed in depth below.
The ninth step can involve moving the holding fixture from the second furnace to the first furnace and allowing the holding fixture to remain in the second furnace for a predetermined amount of time. The predetermined time can be long enough to allow for the formation of a second oxide layer 122 on the golf club head outer surface. The chemical equations that display the chemical reaction that occurs during this step can be seen in
The second oxide layer 122 can comprise both mechanical and physical properties that can affect the durability and performance of the finished golf club head 100. This layer is exposed to the elements and provides the visual aesthetics of the QPQ finish on the golf club head 100. Such mechanical properties can include but are not limited to the hardness and thickness of the second oxide layer 122. Such physical properties can include but are not limited to the second oxide maximum thickness, the second oxide minimum thickness, and the uniformity of the second oxide layer 122 (hereafter alternately referred to “the second oxide uniformity”). The second oxide uniformity can refer to the thickness of the layer being substantially the same throughout the layer. The second oxide uniformity can be quantified by being equal to the difference between the second oxide maximum thickness and the second oxide minimum thickness.
The second oxide layer 122 can comprise both mechanical and physical properties that can affect the durability and performance of the finished golf club head 100. Such mechanical properties can include but are not limited to the hardness and the uniformity of the second oxide layer 122 (hereafter alternately referred to “the second oxide uniformity”). The second oxide uniformity can refer to the thickness of the layer being substantially the same throughout the layer. The second oxide uniformity can be quantified by being equal to the difference between a second oxide maximum thickness and a second oxide minimum thickness. Such physical properties can include but are not limited to the second oxide thickness, the second oxide maximum thickness, and the second oxide minimum thickness.
The second oxide thickness can be defined as the distance from a point where the second oxide layer 122 meets the first oxide layer 120 to a point where the second oxide layer 122 meets the outer surface. The second oxide thickness can be between 0.000045 inches and 0.000115 inches. The second oxide thickness can be between 0.000045 inches and 0.000055 inches, 0.000055 inches and 0.000065 inches, 0.000065 inches and 0.000075 inches, 0.000075 inches and 0.000085 inches, 0.000085 inches and 0.000095 inches 0.000095 inches and 0.000105 inches, or 0.000105 inches and 0.000115 inches. The first oxide thickness can be less than 0.000115 inches, less than 0.000105, less than 0.000105 inches, less than 0.000095, less than 0.000085, less than 0.00075, or less than 0.000065.
The second oxide maximum thickness can be defined as the largest distance from the point where the second oxide layer 122 meets the first oxide layer 120 to the point where the second oxide layer 122 meets the outer surface. The second oxide maximum thickness can be measured in a direction perpendicular to the second oxide layer 122 at the point measurement was taken. The second oxide maximum thickness can be between 0.000075 inches and 0.000115 inches.
The second oxide minimum thickness can be defined as the smallest distance from the point where the second oxide layer 122 meets the first oxide layer 120 to the point where the second oxide layer 122 meets the outer surface. The second oxide minimum thickness can be measured in a direction perpendicular to the nitride layer 230 at the point measurement was taken. The second oxide minimum thickness can be between 0.000050 inches and 0.000075 inches.
As previously mentioned, the second oxide layer 122 comprises the second oxide uniformity. The second oxide uniformity can be defined as the ratio between the second oxide maximum thickness and the second oxide minimum thickness. The uniformity can be between 1.00 and 1.65. The uniformity can be between 1.00 and 1.15, 1.15 and 1.30, 1.30 and 1.45, 1.45 and 1.60, or 1.60 and 1.65. The uniformity can be less than 1.65, less than 1.50, less than 1.45, or less than 1.30. The closer the uniformity is to 1 the more uniform the second oxide thickness is.
The tenth step can involve removing the holding fixture from the first furnace and cooling the club head 100 to a predetermined temperature. In some embodiments, the cooling can be accomplished by allowing the club head 100 to air cool. In other embodiments the club head 100 can be cooled by partially or fully submerging the club head 100 in a medium. The predetermined temperature can be between 60° C. and 100° C. In some embodiments, the predetermined temperature may be between 60° C. and 65° C., 65° C. and 70° C., 70° C. and 75° C., 80° C. and 85° C., 90° C. and 95° C., or 95° C. and 100° C.
The club head 100 can be cooled over a period of time. The period of time can range from 20 minutes to 40 minutes. In some embodiments, the cooling can be performed over a period of time ranging from 20 minutes to 25 minutes, 25 minutes to 30 minutes, 30 minutes to 35 minutes, or 35 minutes to 40 minutes. Once the club head 100 is cooled, the club head 100 can be rinsed with water and then unloaded from the holding fixture.
In some embodiments, the tenth step can further involve allowing the club head 100 to air dry. The club head 100 can be allowed to air dry until it reaches room temperature. In some embodiments, the room temperature can be between 20° C. and 35° C. In some embodiments, the room temperature can be between 20° C. and 25° C., 25° C. and 30° C., or 30° C. and 35° C.
The eleventh step can involve blasting the outer surface to ensure uniformity throughout the second oxide layer 122. This step can involve blasting the golf club with a medium selected from the group consisting of: glass beads, sand, aluminum oxide, silicon carbide, steel shot, and any other suitable form of grit. The grit size can be between #60 grit and #320 grit. The grit size can be between #60 grit and #80 grit, #80 grit and #100 grit, #100 grit and #120 grit, #120 grit and #140 grit, #140 grit and #160 grit, #160 grit and #180 grit, #180 grit and #200 grit, #200 grit and #220 grit, #220 grit and #240 grit, #240 grit and #260 grit, #260 grit and #280 grit, #280 grit and #300 grit, or #300 grit and #320 grit. In one exemplary embodiment, the medium can be glass beads comprising a #220 grit.
Further, the blasting can be performed at a pressure. The pressure can be between 1 and 5 kg/cm2. In one embodiment the pressure can be between 1 kg/cm2 and 2 kg/cm2, 2 kg/cm2 and 3 kg/cm2, 3 kg/cm2 and 4 kg/cm2 or 4 kg/cm2 and 5 kg/cm2. In one exemplary embodiment, the blasting is performed at a pressure of 2 kg/cm2. In another exemplary embodiment, the blasting can be performed at a pressure of 3 kg/cm2. In some embodiments, the fifteenth step can involve first blasting the outer surface with first medium comprising a first grit size at a first pressure and then blasting the outer surface with a second medium comprising a second grit size at a second pressure. As discussed above, the blasting can ensure uniformity throughout the second oxide layer 122, therefore ensuring uniform strength throughout the golf club head outer surface.
In some embodiments, the eleventh step can further include visually inspecting each golf club head 100 to ensure uniformity, similar to the ninth step. The uniformity of the second oxide layer 122 can ensure the surface hardness is uniform, eliminating or minimizing the formation of the cracks 108 formed during the loft/lie adjustment.
An embodiment of the method is as follows: 1) aging the nitriding salt to a temperature of 565° C. for 6 hours, 2) blasting the outer surface of the golf club head, 3) placing the golf club head into a holding fixture, 4) placing the holding fixture in a second furnace and heating the second furnace to 350° C. for a 30 minutes, 5) moving the holding fixture from the second furnace to the first furnace and holding the furnace at 580° C. for 45 minutes to form a nitride layer 6) lowering the temperature of the furnace to 410° C. and holding it there for a 30 minutes to form a first oxide layer on top of the nitride layer, 7) removing the holding fixture from the first furnace, cooling the club head to a temperature, cleaning the club head, and unloading the club head from the holding fixture, 8) blasting the outer surface of the golf club head, 9) visually inspecting the golf club head to ensure uniformity of the outer surface, 10) reloading the golf club head into the holding fixture, 11) placing the holding fixture in the second furnace and heating the second furnace at 410° C. for a 45 minutes to form a second oxide layer, 12) moving the holding fixture from the second furnace to the first furnace and allowing the holding fixture to remain in the first furnace for a predetermined amount of time, 13) removing the holding fixture from the first furnace, cooling the club heads to a predetermined temperature, and cleaning the club heads, 14) allowing the golf club heads to air dry, 15) blasting the outer surface of the golf club head, and 16) visually inspecting the golf club head to ensure uniformity of the outer surface.
The method described above can ensure increased uniformity in the formation of each of the nitride layer 230, first oxide layer 120, and second oxide layer 122. The increased uniformity of the aforementioned layers, and more specifically in the uniformity in the thickness of the layers, can allow for an increase in the integrity of the layers leading to an increase in the mechanical properties of golf club head outer surface.
The increased uniformity in the formation of the nitride layer 230, first oxide layer 120, and second oxide 122 layer yield an improvement in the uniformity of the hardness of the QPQ finish. The hardness of the QPQ finish can be between 55 HRC and 65 HRC. The hardness of the QPQ finish can be between 55 HRC and 60 HRC, or 60 HRC and 65 HRC. The hardness can be 55 HRC, 56 HRC, 57 HRC, 58 HRC, 59 HRC, 60 HRC, 61 HRC, 62 HRC, 63 HRC, 64 HRC, or 65 HRC. The QPQ finish as describe herein can yield a 27% increase in hardness. The QPQ finish as described herein can yield up to a 36% improvement in variation the hardness, improving the uniformity of the hardness throughout the QPQ finish.
The method described above can yield a golf club head having a compound layer or layer with a grade. The compound layer grade or layer grade can refer to the QPQ finish and more specifically to the nitride layer 230, and the first oxide layer 120, and second oxide layer 122. The compound layer grade describes the extent and distribution of porosity within the compound layer. Grades 1, 2, and 3 are considered within an acceptable range of porosity. Grades 4 and 5 are considered to comprise too much porosity to reliably prevent undesirable surface deformation. Specifically, Grades 1 and 2 describe compound layers that are dense and have little to no micropores on the surface. Grade 3 refers to compound layers that are dense with micropores that gradually decrease from the upper layer into the material. Grades 4 and 5 describe compound layers wherein more than ⅔ of the compound layer is occupied by the micropores. In some examples, the golf club head as described herein can comprise a grade 3 compound layer. In some examples, the golf club head as described herein can comprise a grade 2 compound layer. In some examples, the golf club head as described herein can comprise a grade 1 compound layer. The golf club head as described herein can comprise a grade 1, grade 2 or grade 3 compound layer. The golf club head as described herein does not comprise a grade 4 or grade 5 compound layer.
The grade of the compound layer can be affected by the level of porosity in an upper half of the compound layer (at least partially including the first oxide layer 120 and the second oxide layer 122) and the level of porosity in a lower half of the compound layer (at least partially including the nitride layer 130). The high porosity level exhibited at and near the surface is an expected effect of the QPQ process, and allows for surface deformation, including the formation of micro-cracks. Notable differences in the severity of surface deformation and cracking beyond micro-cracking result from significant differences in porosity deeper into the compound layer, below the upper half.
Porosity within the compound layer lower half can create gaps that allow for micro-cracks formed at the surface to extend deeper into the material. Therefore, it can be desirable to have little to no porosity within the compound layer lower half. The percentage of porosity in the compound layer lower half can be between 0% and 5%. The percentage of porosity in the compound layer lower half can be between 0% and 1%, 1% and 2%, 2% and 3%, 3% and 4%, or 4% and 5%. The percentage of porosity in the compound layer lower half can be less than 5%, less than 3%, less than 2%, less than 1%. The low porosity percentage in the compound layer lower half results in a very minimal chance that a micro-crack formed in the upper half will connect with any of the few gaps formed by porosity in the lower half, thereby rendering it very unlikely that a crack will deepen to extend into the lower half and become visible to the eye at arm's length.
The percentage of porosity in the compound upper half can be between 40% and 65%. The percentage of porosity in the compound layer upper half can be between 40% and 45%, 45% and 55%, 55% and 60%, or 60% and 65%. Even though the high porosity level exhibited in the compound layer upper half is an expected effect of the QPQ process, and allows for surface deformation, including the formation of micro-cracks, but prevents the micro-cracks from expanding and deepening into the lower half of the compound layer.
The application of the method described herein can improve hardness uniformity and wear resistance of golf club head outer surface, while still allowing the core 110 to remain softer and more ductile. This is extremely important for golf club heads, in order to maintain flexibility for loft/lie adjustable, as well as desirable feel and sound characteristics. The application of this QPQ method can allow for a golf club head 100 comprising an outer surface with the ability to withstand the forces applied at impact and during the loft/lie adjustment process without impacting the feel of the golf club head 100 at impact.
Heat treatment of metals increases hardness, while also increasing porosity. Porosity increases the likelihood of cracks 108 by creating gaps in the material. Porosity near the surface allows for the creation of micro-cracks. The existence of greater porosity in regions deeper beneath the surface of the material, however, allows for cracks to propagate further into the material, resulting in longer and wider cracks. Specifically, micro-cracks that connect with gaps resultant from porosity gain volume (depth and width) from the gaps. These longer and wider cracks are more likely to combine or interconnect to stretch further along the surface, thereby increasing visibility and decreasing integrity. A greater porosity percentage beyond the surface region results in an increased frequency of deep cracks due to the increased frequency of gaps within the material. A low porosity percentage may result in the occurrence of cracks that extend to the same maximum depth as those of a material with a greater porosity percentage, but will exhibit significantly fewer deep cracks, thereby maintaining durability.
A typical QPQ method results in the hardened surface, including the region of increased porosity, extending deeper into the material. The QPQ method described above results in a desirably hardened surface, while retaining the high porosity that results in the increased hardness very near to the surface. As a result, the cracks are desirably less likely to extend deep beneath the surface or far across the surface. Upon bending, the QPQ-treated surface is more likely to exhibit a series of micro-cracks than thick, deep cracks, thereby retaining resiliency, while providing the hardness resultant from the QPQ process.
Described herein is a comparison of the physical properties of a control golf club head produced using the traditional QPQ method detailed in Table 2, below, and an exemplary golf club head produced using the QPQ method detailed in Table 3, below. More specifically, this example displays the difference in the thicknesses and uniformity of the nitride layers, the first oxide layer and the second oxide layer.
As shown in
As shown above in Table 4, the exemplary golf club head yielded a 34.99% improvement in the uniformity of the Nitride layer over the control golf club head. The uniformity of the nitride layer further ensures the uniformity of the first and second oxide layer by providing the first oxide layer a consistent surface for expansion and growth. Any uniformity of the nitride layer can translate directly into the first oxide layer and then to the second oxide layer. Further, the exemplary golf club head yielded a 67.83% improvement in the standard deviation of the nitride layer thickness over the control golf club head. The drastic improvement in the standard deviation of nitride layer thickness further displays the uniformity in the thickness of the nitride layer thickness, as the standard deviation measures the amount of variation in the thickness.
As shown above in Table 5, the exemplary golf club head yielded a 1.93% decrease in the uniformity of the first oxide layer. However, the exemplary golf club head did yield a 40.23% improvement in the standard deviation of the first oxide layer thickness over the control golf club head. The decrease in uniformity was considered to be negligible due to the drastic improvement in the standard deviation of the first oxide layer thickness over the control golf club head. As previously mentioned, the standard deviation of the first oxide layer thickness displays the uniformity in the thickness of the first oxide layer thickness, as the standard deviation measures the amount of variation in the thickness.
Further as shown above in Table 5, the average thickness of exemplary first oxide layer is much smaller than the control first oxide layer. The smaller average thickness provides a thinner first oxide layer that is less brittle and less prone to large cracks.
As shown above in Table 6, the Exemplary Golf Club Head yielded a 12.08% improvement in the uniformity of the second oxide layer. Further, the Exemplary Golf Club Head yielded a 19.05% improvement in the standard deviation of the second oxide layer thickness over the Control Club Head. The drastic improvement in the standard deviation of the first oxide layer thickness over the control golf club head further displays the uniformity in the thickness of the second oxide layer thickness, as the standard deviation measures the amount of variation in the thickness.
Further as shown above in Table 6, the average thickness of exemplary second oxide layer is much smaller than the control second oxide layer. The smaller average thickness provides a thinner second oxide layer that is less brittle and less prone to large cracks.
In conclusion, the additional blasting steps of the QPQ method described herein were shown to increase uniformity of each of the nitride layer, first oxide layer, and second oxide layer. This increased uniformity promotes bonding of each layer, reducing porosity and increasing hardness, as detailed in Examples II and V, below. Specifically, the smooth surface resulting from the blasting steps prevents the formation of imperfections between layers within the compound layer, thereby reducing the frequency of deep crack formation, as detailed in Examples III and IV, below.
Example II provides a comparison of degree and depth of porosity within the compound or finish layer applied to the surface of a golf club head using the methods described herein and traditional QPQ methods. Described herein are two samples of a single exemplary embodiment of a golf club head (hereafter referred to as “Exemplary Club Head 1” and “Exemplary Club Head 2”) with an integral hosel structure that was made of an 8620 steel alloy which received a post-fabrication QPQ treatment, as described above and in the steps detailed in
The depth and degree of high porosity of Exemplary Club Head 1 and Exemplary Club Head 2 were compared with that of two samples of a similar golf club head (hereafter referred to as “Control Club Head 1” and “Control Club Head 2”), which received a traditional QPQ treatment. The traditional QPQ treatment consists of the steps described in Table 2 in Example I, above.
Referring to Table 7, above, Control Club Head 1 and Control Club Head 2 show a high level of porosity in an upper half of the compound layer—39% and 47%, respectively. Exemplary Club Head 1 and Exemplary Club Head 2 similarly show a high level of porosity in the upper half of the compound layer—59% and 45%, respectively. The high porosity level exhibited at and near the surface is an expected effect of either QPQ process, and allows for surface deformation, including the formation of micro-cracks. Notable differences in the severity of surface deformation and cracking beyond micro-cracking result from significant differences in porosity deeper into the compound layer, below the upper half.
Again referring to Table 7, Control Club Head 1 and Control club head 2 shows a moderate level of porosity in a lower half of the compound layer—15% and 13%, respectively. Exemplary Club Head 1 and Exemplary Club Head 2 show a very low level of porosity in the lower half of the compound layer—1% and <1%, which is significantly lower than the lower half of the compound layer of Control Club Head 1 and Control Club Head 2. Porosity within the compound layer lower half creates gaps that allow for micro-cracks formed at the surface to extend deeper into the material. Because of the similarly high porosity seen in all of the tested club heads, micro-cracks are expected to form at the surface, but have no noticeable effect on the strength of the coating, and are not clearly visible to the user. The extremely low porosity of Exemplary Club Head 1 and Exemplary Club Head 2 results in a more resilient compound layer that resists surface deformation and prevents the formation of deep cracks.
Each sample was graded based on the extent of porosity exhibited within the compound layer, hereafter referred to as the “oxidation loose layer grade” or “compound layer grade”. Referring to Table 1, Grades 1, 2, and 3 are considered within an acceptable range of porosity. Grades 4 and 5 are considered to comprise too much porosity to reliably prevent undesirable surface deformation. Specifically, Grades 1 and 2 describe compound layers that are dense and have little to no micropores on the surface to enable the micro-cracks to expand or deepen. Grade 3 refers to compound layers that are dense with micropores that gradually degrease from the upper layer into the material. Grades 4 and 5 describe compound layers wherein more than ⅔ of the compound layer is occupied by the micropores, and lead to visible cracks at arm's length. As shown above in Table 7, both Control Club Head 1 and Control Club Head 2 received a failing compound layer grade of 4, while Exemplary Club Head 1 and Exemplary Club Head 2 received an acceptable compound layer grade of 3. Therefore, the traditional QPQ method was unable to provide the material with a coating that contained an acceptable level of porosity. The QPQ method described herein produced a material coating that fell within an acceptable porosity level while comprising the desirable hardened surface, providing the user with the resiliency required to prevent surface deformation upon bending.
Example III discusses the occurrence of substantial visible surface deformation resulting from stress on a club head treated with the QPQ method described herein. Specifically, Example 5 considers test data related to bending the hosel to adjust loft angle and lie angle and the formation of visible cracks in the bending region.
Described herein are samples of a single exemplary embodiment of a golf club head (hereafter referred to as “Exemplary Club Heads”) with an integral hosel structure that was made of an 8620 steel alloy and received a post-fabrication QPQ treatment, as described above and in the steps detailed in
When a club head hosel is forcibly bent following manufacturing, the applied force produces visible marks at the bend site due to material deformation. The amount of material surface deformation following bending was analyzed and recorded on a qualitative feedback scale. Eighteen Exemplary Club Heads were forcibly bent at the hosel to a degree ranging between 3° and 5° from neutral starting position. The Exemplary Club Heads were measured in this way for upright and flattened lie adjustments as well as open and closed loft adjustments. Table 8 below details the degree of bending attempted and resultant surface deformation rating.
The values recorded in the table indicate the change in loft angle achieved before surface deformation became substantially noticeable at arm's length. Minor variance in degree bent was due to human error within the bending process and is overall negligible, as the bending of the loft and lie angles on a post-manufactured club head can be imprecise. As shown in Table 8, the Exemplary Club Heads were all able to be bent to a satisfactory degree of greater than 3 degrees without easily noticeable evidence of surface deformation at arm's length. The Exemplary Club Heads remained visibly unaffected by the applied force, while maintaining the ability to be successfully bent to desirable degrees without failure.
Example IV provides a qualitative comparison (i.e. crack development and surface characteristics) illustrating the effect of applying the QPQ method described herein on crack development and surface characteristics. Specifically, Example IV provides a comparison of images taken following bending of the hosel, which depict surface deformation in the region of the hosel.
Visibility, frequency, and size of cracks were observed and analyzed qualitatively for an exemplary club head treated with the QPQ method described herein, as well as for a control club head which received a typical QPQ treatment. The exemplary club head treated with the QPQ method described herein (hereafter referred to as the “Exemplary Club Head”) comprised an integral hosel structure that was made of an 8620 steel alloy which received a post-fabrication QPQ treatment, as described above and in the steps detailed in
The extent of cracking seen on the surface of the Exemplary Club Head was compared with that of a similar golf club head (hereafter referred to as the “Control Club Head”) which received a traditional QPQ treatment. The traditional QPQ treatment consisted of the steps described in Table 2 in Example I, above. Images of the surface deformation exhibited by the Exemplary Club Head, following hosel bending, are shown in
The compound layer, and each individual layer (nitride and oxide layers) that make up the compound layer, appear significantly smoother and more even, with fewer impurities when the base material is treated with the QPQ method described herein, in comparison with a base material treated by a traditional QPQ method. Frequency and severity of cracks visible by the naked eye, when viewed at arm's length, or in magnified images, is greatly reduced when the QPQ treatment described herein is applied to the material surface, when compared with a surface treated with a traditional QPQ treatment method.
Example V provides a comparison of hardness measurements recorded on the coating surface of a golf club head treated. Described herein are two samples of a single exemplary embodiment of a golf club head (hereafter referred to as “Exemplary Club Head 1” and “Exemplary Club Head 2”) with an integral hosel structure that was made of an 8620 steel alloy which received a post-fabrication QPQ treatment, as described above and in the steps detailed in
The hardness of Exemplary Club Head 1 and Exemplary Club Head 2 were compared with that of two samples of a similar golf club head (hereafter referred to as “Control Club Head 1” and “Control Club Head 2”) which received a traditional QPQ treatment. The traditional QPQ treatment consists of the steps described in Table 2 in Example I, above.
Referring to Table 9 and Table 10, above, the hardness of the QPQ coating was analyzed on the HRC Rockwell Scale for each of the Control Club Head samples and Exemplary Club Head samples. Data was collected from five readings at different points on the surface, and averaged to determine an average hardness across the surface. The hardness is substantially greater in Exemplary Club Head 1 and Exemplary Club Head 2, when compared with Control Club Head 1 and Control Club Head 2. Specifically, the hardness of the coating formed by the QPQ method described herein of Exemplary Club Head 1 and Exemplary Club Head 2, was 27% greater than the hardness of the coating formed by the traditional QPQ method of Control Club Head 1 and Control Club Head 2.
The hardness values recorded in each of the five readings can indicate uniformity of the hardness across the surface. A span of hardness values collected in the five readings was reduced by 36.7%-54.5% in the Exemplary Club Heads which were treated with the QPQ method described herein, when compared with the Control Club Heads treated with the traditional QPQ method. On average, the QPQ method described herein reduced variation in surface hardness values measured in Exemplary Club Head 1 and Exemplary Club Head 2 by more than 46%.
A greatest deviation from the mean was found to be substantially lower in Exemplary Club Head 1 and Exemplary Club Head 2 than Control Club Head 1 and Control Club Head 2. Hardness readings deviated 1.85%-2.25% and 1.59%-1.72% from the mean in Exemplary Club Head 1 and Exemplary Club Head 2, respectively. Hardness readings deviated 4.74%-4.94% and 4.96%-5.95% from the mean in Control Club Head 1 and Control Club Head 2, respectively. The improvement in hardness and hardness uniformity, improve the wear resistance of golf club head outer surface, while still allowing the core 110 to remain softer and more ductile.
Replacement of one or more claimed elements constitutes reconstruction and not repair. Additionally, benefits, other advantages, and solutions to problems have been described with regard to specific embodiments. The benefits, advantages, solutions to problems, and any element or elements that may cause any benefit, advantage, or solution to occur or become more pronounced, however, are not to be construed as critical, required, or essential features or elements of any or all of the claims, unless such benefits, advantages, solutions, or elements are expressly stated in such claims.
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 such as the United States Golf Association (USGA), the Royal and Ancient Golf Club of St. Andrews (R&A), etc.), golf equipment related to the apparatus, methods, and 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 apparatus, methods, and articles of manufacture described herein may be advertised, offered for sale, and/or sold as conforming or non-conforming golf equipment. The apparatus, methods, and articles of manufacture described herein are not limited in this regard.
While the above examples may be described in connection with a iron-type golf club, the apparatus, methods, and articles of manufacture described herein may be applicable to other types of golf club such as a driver wood-type golf club, a fairway wood-type golf club, a hybrid-type golf club, an iron-type golf club, a wedge-type golf club, or a putter-type golf club. Alternatively, the apparatus, methods, and articles of manufacture described herein may be applicable to other types of sports equipment such as a hockey stick, a tennis racket, a fishing pole, a ski pole, etc.
Moreover, embodiments and limitations disclosed herein are not dedicated to the public under the doctrine of dedication if the embodiments and/or limitations: (1) are not expressly claimed in the claims; and (2) are or are potentially equivalents of express elements and/or limitations in the claims under the doctrine of equivalents.
Various features and advantages of the disclosure are set forth in the following clauses and claims.
Clause 1. A method for treating a golf club head, the method comprising: aging a nitriding salt in a first furnace for a predetermined amount of time; blasting an outer surface of the golf club head; placing a holding fixture in a second furnace and heating the second furnace to a predetermined temperature for a predetermined amount of time; moving the holding fixture from the second furnace to the first furnace and allowing the holding fixture to remain in the first furnace for a predetermined amount of time, wherein a nitride layer is formed on the outer surface; lowering the temperature of the first furnace to a predetermined temperature for a predetermined amount of time, wherein a first oxide layer grows on top of the nitride layer; removing the holding fixture from the first furnace, cooling the golf club head to a predetermined temperature, cleaning the golf club head, and unloading the golf club head from the holding fixture; blasting the outer surface of the golf club head; placing the holding fixture in the second furnace and heating the second furnace to a predetermined temperature for a predetermined amount of time; moving the holding fixture from the second furnace to the first furnace and allowing the holding fixture to remain in the first furnace for a predetermined amount of time, wherein a second oxide layer grows on the first oxide layer; removing the holding fixture from the first furnace, cooling the golf club head to a predetermined temperature, and cleaning the golf club head; and blasting the outer surface of the golf club head, wherein the nitride layer, the first oxide layer and the second oxide layer are uniform.
Clause 2. The method of claim 1, wherein the nitriding salt comprises a CNO concentration between 28% and 36%.
Clause 3. The method of claim 1, wherein the blasting of step (b) is performed with a 220#grit glass bead.
Clause 4. The method of claim 1, wherein the nitride layer comprises a nitride thickness between 0.00025 inches and 0.00060 inches.
Clause 5. The method of claim 4, wherein the nitride layer comprises a nitride max thickness and nitride min thickness; wherein the nitride max thickness is between 0.00025 inches and 0.00045 inches, and the nitride min thickness is between 0.00045 inches and 0.00060 inches.
Clause 6. The method of claim 5, wherein the nitride layer comprises a nitride uniformity that is less than 1.25.
Clause 7. The method of claim 1, wherein the first oxide layer comprises a first oxide thickness is less than 0.000115 inches.
Clause 8. The method of claim 7, wherein the first oxide layer comprises a first oxide max thickness and first oxide min thickness; wherein the first oxide max thickness is between 0.000075 inches and 0.000115 inches, and the first oxide min thickness is between 0.000050 inches and 0.000075 inches.
Clause 9. The method of claim 8, wherein the first oxide layer comprises a first oxide uniformity that is less than 1.85.
Clause 10. The method of claim 1, wherein the second oxide layer comprises a second oxide thickness is less than 0.000115.
Clause 11. The method of claim 10, wherein the second oxide layer comprises a second oxide max thickness and second oxide min thickness; wherein the second oxide max thickness is between 0.000075 inches and 0.000115 inches, and the second oxide min thickness is between 0.000050 inches and 0.000075 inches.
Clause 12. The method of claim 11, wherein the second oxide layer comprises a first oxide uniformity that is less than 1.65.
Clause 13. A golf club head comprising: a body having a top rail opposite a sole, a toe opposite a heel; a hosel coupled to the club body and having a first end proximate the heel and a second end opposite the first end; an outer surface comprising a QPQ finish; wherein the QPQ finish comprise a nitride layer, a first oxide layer, and a second oxide layer; wherein the outer surface comprises a grade 3 QPQ finish; wherein the nitride layer comprises a nitride uniformity between 1.00 and 1.25; wherein the first oxide layer comprises a first oxide uniformity between 1.00 and 1.25; and wherein the second oxide layer comprises a second oxide uniformity between 1.00 and 1.25.
Clause 14. The golf club head of claim 13, where the QPQ finish has a hardness between 55 HRC and 65 HRC.
Clause 15. The golf club head of claim 13, wherein the nitride layer comprises a nitride thickness between 0.00025 inches and 0.00060 inches.
Clause 16. The golf club head of claim 13, wherein the nitride layer comprises a nitride max thickness and nitride min thickness; and wherein the nitride max thickness is between 0.00025 inches and 0.00045 inches and the nitride min thickness is between 0.00045 inches and 0.00060 inches.
Clause 17. The golf club head of claim 13, wherein the first oxide layer comprises a first oxide thickness is less than 0.000115 inches.
Clause 18. The golf club head of claim 13, wherein the first oxide layer comprises a first oxide max thickness and first oxide min thickness, wherein the first oxide max thickness is between 0.000075 inches and 0.000115 inches, and the first oxide min thickness is between 0.000050 inches and 0.000075 inches.
Clause 19. The golf club head of claim 13, wherein the second oxide layer comprises a second oxide thickness is less than 0.000115.
Clause 20. The golf club head of claim 13, wherein the second oxide layer comprises a second oxide max thickness and second oxide min thickness; wherein the second oxide max thickness is between 0.000075 inches and 0.000115 inches, and the second oxide min thickness is between 0.000050 inches and 0.000075 inches.
This claims the benefit of prior-filed U.S. Provisional Application No. 63/383,234 filed Nov. 10, 2022, the contents of which are fully incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63383234 | Nov 2022 | US |
