Golf club

Abstract

Conventional technology only vaguely claims that it can generate good backspin even when wet, but it does not provide any concrete experimental data to support the idea that the number, arrangement, and shape of the protrusions affect the amount of backspin and distance compared to when the ball is dry. Therefore, it does not clearly state any objective and specific effects based on such experimental data. [Solution] To provide a golf club with grooves or bumps on the face that are shaped in such a way that there is virtually no difference in the amount of backspin whether the surface is dry or wet.

Description

Technical Field

[0001] The present invention relates to a golf club used in a sports competition in which, according to the golf rules (R&A), a ball is hit with a golf club starting from the teeing area and a single hole is defined as the process until the ball is put into the hole (cup) on the green, and the competition is to complete a plurality of holes (usually 18 holes) with as few strokes as possible. In this specification, for the sake of convenience of explanation, the description is based on the premise that a right-handed golfer uses a right-handed golf club. However, basically, even when a left-handed golfer uses a left-handed golf club, the same configuration can be adopted and the same effects can be enjoyed.

Background Art

[0002] Generally, on the face surface of the club head of a golf club, a plurality of score line grooves and fine irregularities may be provided on the surface portion other than the score line grooves. These score line grooves and fine irregularities are caused by the frictional resistance generated between the face surface of the club head and the ball when the golfer holds the golf club and swings, and impacts the ball at the tip of the golf shaft. By applying spin to the ball, particularly backspin, which is the spin in the opposite direction to the flying direction of the ball, it is possible to control the flying distance and launch angle of the ball.

[0003] Also, generally, golf clubs are classified into types such as drivers, fairway woods, irons, wedges, putters, etc. according to their uses. Among these, for the golf club called a wedge, there are four types: PW (pitching wedge), GW (gap wedge (also called AW: approach wedge)), SW (sand wedge), and LW (lob wedge), depending on the loft angle and flying distance of the club head. Typically, golfers select and use golf clubs that they deem appropriate, taking into account various conditions such as weather (sunny, rainy, etc.) and course conditions (dry, wet, etc.).

[0004] In other words, applying scorelines or fine irregularities to the face of the club head to impart backspin to the ball upon impact has been a long-standing practice.

[0005] Furthermore, the amount of backspin is greatly affected by weather and humidity. Specifically, even if the exact same swing is used, in rainy weather, compared to sunny weather, water gets between the clubhead face and the ball at impact, reducing friction and thus significantly decreasing the amount of backspin. Also, even in sunny weather, for example, the golf course may be damp in the morning due to condensation (wet conditions), while it may be dry by the afternoon as the moisture evaporates (dry conditions). In such cases, even if the exact same swing is used, a significant difference in the amount of backspin will occur.

[0006] Therefore, conventionally, the shape of the club head face has been designed to allow for control of backspin to a level similar to that of a dry golf course, even when the course is wet.

[0007] One example of such a golf club is the invention described in Patent Document 1. Figure 7 shows an example of the prior art. Figure 8 shows an example of a magnified view of the prior art. Patent Document 1 describes a club head in which recesses 10B are formed on the lower half of the face surface 2 of the club head by a pulsed laser, and the remaining protrusions 10A are arranged in a staggered pattern, as shown in Figure 7. Furthermore, as shown in Figure 8, Patent Document 1 claims that the gaps between the remaining protrusions on the face surface 2 of the club head prevent water from being trapped in the recesses, thus allowing for good backspin even in wet conditions. In addition, Patent Document 1 suggests that the shape of the protrusions be approximately square, approximately circular, approximately regular pentagon, approximately triangular, and approximately hexagonal, and that good backspin can be applied in wet conditions in any of these shapes. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2018-102446 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, this conventional technology only abstractly claims that it can generate good backspin even when wet, and it has a major problem in that it does not provide any concrete experimental data to support how much the amount of backspin and distance are the same as when wet, depending on the number, arrangement, and shape of the protrusions, and does not clearly state objective and specific effects based on such experimental data.

[0010] It is said that as golfers, both professionals and amateurs, become more skilled, they can reproduce the same swing when aiming for the same spot on the green. Therefore, for golfers, a golf club that allows them to hit the ball to the same spot regardless of whether the green is dry or wet would be extremely convenient, as it would improve reproducibility, increase the probability of getting the ball close to the pin (cup) on the green, and eliminate the need to change their swing technique. In other words, there is a desire for golf clubs with grooves or ridges on the face that result in virtually no difference in backspin regardless of whether the green is dry or wet. [Means for solving the problem]

[0011] Based on the problems described above, the present invention aims to provide a golf club with grooves or irregularities on the face surface that result in virtually no difference in backspin, whether the surface is dry or wet.

[0012] Specifically, the first invention provides a golf club having more than 2,000 protrusions arranged in a roughly regular hexagonal shape on its face.

[0013] Furthermore, the second invention provides a golf club in which, in addition to the above features, the convex portion is frustoconical in shape.

[0014] Furthermore, the third invention provides a golf club that, in addition to the above features, has a frustoconical base with a diameter in the range of 0.3 mm to 0.5 mm and a frustoconical apex with a diameter in the range of 0.16 mm to 0.22 mm.

[0015] Furthermore, the fourth invention provides a golf club in which, in addition to the above features, the distance between adjacent frustums of cones is in the range of 0.35 millimeters to 0.75 millimeters between the centers of the apex faces.

[0016] Further, the fifth invention provides a golf club in which, in addition to the above characteristics, the height of the frustum of a cone is in the range of 0.020 millimeters to 0.025 millimeters.

[0017] Further, the sixth invention provides a golf club in which, in addition to the above characteristics, the material of the face surface is metal.

Effect of the Invention

[0018] From the above, in the present invention, it is possible to provide a golf club having grooves or irregularities on the face surface in a shape such that there is almost no difference in the amount of backspin in both dry and wet conditions.

Brief Description of the Drawings

[0019] [Figure 1] A diagram showing an example of the shape of the golf club of Embodiment 1 [Figure 2] A diagram showing an example of the ratio of the width of the face surface to the width of the uneven processing area of the golf club of Embodiment 1 [Figure 3] A vertical cross-sectional view showing an example of the shape of the convex portion of the golf club of Embodiment 1 [Figure 4] A diagram showing an example in which a round shape occurs between the top surface and the side surface of the frustum of a cone convex portion of the golf club of Embodiment 1 [Figure 5] A diagram showing an enlarged view and a cross-sectional view of the shape of the golf club of Embodiment 2 [Figure 6] A diagram showing an example of the distance between adjacent frustums of a cone in the golf club of Embodiment 2 [Figure 7] A diagram showing an example of the prior art [Figure 8] A diagram showing an enlarged view of an example of the prior art [Figure 9] A diagram showing the golf clubs (4 types) used for verification [Figure 10] A diagram showing the front view and side view of the test hitting machine manufactured for verification [Figure 11] An enlarged view of the side view of the test hitting machine manufactured for verification [Figure 12] A diagram showing an example of how to view the verification data [Figure 13] A schematic diagram illustrating the verification data "(1) Ball speed (m / s)". [Figure 14] This diagram shows a comparison of four types of golf clubs in dry and wet conditions, based on the verification data "(1) Ball Speed ​​(m / s)". [Figure 15] The diagram shows a comparison of dry and wet conditions for four different types of golf clubs, using the verification data "(1) Ball Speed ​​(m / s)". [Figure 16] This diagram schematically illustrates the verification data "(2) Launch Angle (deg)". [Figure 17] This diagram shows a comparison of four types of golf clubs in dry and wet conditions, based on the verification data "(2) Launch Angle (deg)". [Figure 18] The diagram shows a comparison of the launch angle (deg) for each of the four types of golf clubs, comparing dry and wet conditions, which is the verification data. [Figure 19] A schematic diagram illustrating the verification data "(3) Launch direction (deg)". [Figure 20] This diagram shows a comparison of four types of golf clubs in dry and wet conditions for the verification data "(3) Launch direction (deg)". [Figure 21] The diagram shows a comparison of dry and wet conditions for each of the four types of golf clubs used in the verification data "(3) Launch direction (deg)". [Figure 22] This diagram schematically illustrates the verification data "(4) Spin amount (rpm)". [Figure 23] This diagram shows a comparison of four types of golf clubs in dry and wet conditions, based on the verification data "(4) Spin rate (rpm)". [Figure 24] The diagram shows a comparison of dry and wet conditions for each of the four types of golf clubs, using the verification data "(4) Spin rate (rpm)". [Figure 25] This diagram schematically illustrates the verification data, "(5) Highest point reached (m)". [Figure 26]This diagram shows a comparison of four types of golf clubs in dry and wet conditions for the verification data "(5) Maximum reach (m)". [Figure 27] The diagram shows a comparison of dry and wet conditions for each of the four types of golf clubs, specifically for the verification data "(5) Maximum reach (m)". [Figure 28] A schematic diagram illustrating the verification data "(6) Carry distance (yd)". [Figure 29] This diagram shows a comparison of four types of golf clubs in dry and wet conditions for the verification data "(6) Carry distance (yd)". [Figure 30] The diagram shows a comparison of dry and wet conditions for each of the four types of golf clubs, using the verification data "(6) Carry distance (yd)". [Modes for carrying out the invention]

[0020] The embodiments of the present invention will be described below with reference to the attached drawings. The relationship between the embodiments and the claims is as follows: The description of Embodiment 1 mainly relates to claims 1 and 2, the description of Embodiment 2 relates to claims 3, 4 and 5, and the description of Embodiment 3 relates to claims 6 and 7. The present invention is not limited in any way to these embodiments and can be implemented in various forms without departing from its essence.

[0021] <Embodiment 1 (mainly corresponding to claims 1 and 2)> <Overview of Embodiment 1>

[0022] The invention of this embodiment is a golf club having 2,000 or more protrusions arranged in a substantially regular hexagonal shape on its face. Furthermore, the invention of this embodiment is a golf club in which the shape of the protrusions is a frustoconical shape. <Configuration of Embodiment 1>

[0023] <Embodiment 1 Configuration: Main Part Configuration>

[0024] Figure 1 shows an example of the shape of the golf club of this embodiment. The golf club of this embodiment has more than 2000 protrusions arranged in a roughly regular hexagonal shape on the face surface 0101 of the club head 0100. Here, Figure 1(a) shows an example of the overall shape of the face surface. Figure 1(b) is an enlarged view of the area enclosed by the rectangle 0102 in Figure 1(a). Although not clearly shown in Figure 1(a), as clearly shown in Figure 1(b), multiple protrusions 0103 are arranged on the face surface 0101 in a roughly regular hexagonal shape. In Figure 1(b), the area enclosed by the circle 0104 is the part that forms a roughly regular hexagon, and is formed by a total of 7 protrusions: 6 protrusions that make up the vertices of the roughly regular hexagon and 1 protrusion located in the center of these. Figure 1(c) shows the area enclosed by the circle 0104 in Figure 1(b), which consists of multiple protrusions arranged in a roughly regular hexagon. It can be seen that the roughly regular hexagon is formed by a total of seven protrusions: six protrusions that make up the vertices and one protrusion located in the center. The number 2000 or more refers to the number of protrusions that form this roughly regular hexagon, counted as one.

[0025] <Embodiment 1 Configuration: Regarding the number of protrusions>

[0026] The reason for having more than 2000 protrusions is as follows: In order to make it easier to impart spin to the ball when struck, it is necessary to create friction between the ball and the protrusions on the clubface at impact. To achieve this, it is necessary to increase the contact area between the ball and the clubface by providing a considerable number of protrusions. Based on the verification results described later, 2000 protrusions are the minimum number required to create adequate friction between the ball and the protrusions on the clubface at impact, and it becomes difficult to create adequate friction with fewer than 2000 protrusions.

[0027] However, more protrusions are not always better. In order to achieve the same spin rate in wet conditions as in dry conditions, it is necessary to ensure a certain amount of surface area in the recesses for drainage, and therefore, it is necessary to maintain a certain distance between adjacent protrusions. If too many protrusions are placed on the limited surface area of ​​the clubface, it becomes difficult to maintain this distance between adjacent protrusions. Therefore, from this perspective, it can be said that there is a certain upper limit to the optimal number of protrusions.

[0028] Based on the above and taking into account the verification results described later, the number of protrusions provided on the face surface of the club head of the golf club in this embodiment is preferably 2,000 to 4,500, more preferably 3,000 to 4,000, and even more preferably around 3,300. If there are fewer than 2,000 protrusions, the contact area between the ball and the face surface cannot be sufficiently secured, leading to a decrease in frictional force. On the other hand, if there are more than 4,500 protrusions, it becomes difficult to sufficiently secure the spacing between adjacent protrusions, resulting in poor drainage performance.

[0029] Furthermore, as shown in Figure 1(d), it is important to note that one of the protrusions is formed in the shape of a frustocone, with a base surface 0105, a top surface 0106, and a side surface 0107 connecting the base and top surfaces. Details will be described later.

[0030] <Embodiment 1 Configuration: Ratio of the total surface area to the area of ​​the textured region>

[0031] Figure 2 shows an example of the ratio of the total face area to the area of ​​the textured region in this embodiment. As shown in this figure, the face 0201 of a typical club head is approximately 45-55 millimeters vertically and 55-60 millimeters horizontally. In other words, the area is estimated to be around 2500-3000 square millimeters. On the other hand, the textured region 0202 has scoreline grooves that extend to about 80% of the face width. This is in compliance with the Rules of Golf (R&A). In other words, according to the Rules of Golf (R&A), a "smooth area (area where processing is prohibited)" is required at the upper and lower ends of the face, so there is a margin of several millimeters (smooth area) at the upper and lower ends of the face of the golf club indicated by the dotted rectangle. Furthermore, according to the Rules of Golf (R&A), it is also restricted from providing a textured region at the edges of the face (toe side and heel side). Therefore, even when considering the scoreline grooves and textured areas together, they are thought to occupy only about 60-75% of the total face surface area. In other words, by placing the appropriate number of protrusions in the appropriate arrangement within this area, it becomes possible to apply the appropriate amount of backspin.

[0032] <Embodiment 1: Configuration: Convex portions aligned in a roughly regular hexagonal shape>

[0033] The distinctive feature of this invention lies in the arrangement of protrusions in a roughly regular hexagon. A key characteristic of the regular hexagon is that the spacing between all protrusions is the same, and that the hexagon possesses not only point symmetry but also rotational symmetry at 60-degree intervals. These characteristics result in a nearly identical contact state between the protrusions and the golf ball at impact, regardless of the angle of contact with the ball. This uniform spacing between all protrusions, preventing anisotropy in ball contact at impact, is unique to the arrangement of the protrusions in a regular hexagon. Furthermore, by maintaining an appropriate distance between the protrusions, it is possible to adjust the moisture content in the ball contact area on the clubface. Additionally, since moisture detaches evenly in all directions, the residual moisture is uniform across the entire clubface, achieving uniformity in contact between the ball and the clubface from the perspective of the effects of residual moisture (see Figure 1(c)). This is further evident from the verification results described later.

[0034] <Embodiment 1 Configuration: Shape of the protrusion>

[0035] There are no particular limitations on the shape of the protrusion of the golf club in this embodiment. For example, the shapes of the protrusion of the golf club in this embodiment may include cylindrical, truncated cone, triangular prism, truncated triangular pyramid, square prism, truncated square pyramid, pentagonal prism, truncated pentagon, hexagonal prism, truncated hexagon, other polygonal prisms, truncated polygonal pyramids, star prisms, truncated star pyramids, hemispheres, dome shapes, etc.

[0036] However, based on the verification results described later, the shape that most suitably achieves the objective of the present invention is a frustoconical shape. The convex portion shown in Figure 1(c) also represents a frustoconical shape with a circular base and apex.

[0037] Figure 3 is a vertical cross-sectional view showing an example of the shape of the convex portion 0301 on the face of the golf club of this embodiment, and shows an example of the shape when the convex portion is frustoconical. Note that the current Rules of Golf (R&A) have detailed regulations regarding the shape of the convex portion, such as not having sharp edges or raised edges. These Rules of Golf (R&A) apply to official matches all over the world, including Japan, regardless of whether they are professional or amateur, and it is desirable that the shape of the convex portion of the golf club according to the present invention conforms to these rules, and the frustoconical shape of the convex portion conforms to these rules.

[0038] <Embodiment 1 Configuration: Dimensions of the protrusion>

[0039] The dimensions of the protrusions are designed to allow for the arrangement of 2000 or more protrusions at appropriate intervals on the face of the club head (for example, the average surface area of ​​a wedge face is said to be approximately 23 to 28 square centimeters). Furthermore, they are appropriately designed to achieve the objective of the present invention, which is to make the spin rate similar in wet and dry conditions. The preferred dimensions of the protrusions will be described in Embodiment 2 below.

[0040] <Embodiment 1: Configuration: Material of the protruding part>

[0041] There are no particular limitations on the material of the protrusions. Generally, the protrusions are formed on the face of the club head by milling or laser milling, so naturally they are made of the same material as the face of the club head. In this embodiment, as described below, it is assumed that the protrusions are formed by laser milling, so in this case as well, they are made of the same material as the face. Here, the material of the face is often selected based on the characteristics required of the golf club. For example, in the case of a driver, a high-strength, high-rebound material is required, so titanium alloys, forged titanium, maraging steel, and carbon composite materials can be used. In the case of a fairway wood, since it is often hit from the grass on the fairway, a balance between a thin face and strength is important, so maraging steel, stainless steel, and titanium can be used. In the case of an iron, precision is important, and the material is selected considering the feel and spin performance, so soft iron (forged), stainless steel, and maraging steel can be used. Furthermore, in the case of wedges, spin performance and feel are considered important, and accuracy and ball contact are generally prioritized, so materials such as soft iron (forged), carbon steel, and stainless steel can be used.

[0042] <Embodiment 1: Configuration: Method for processing the protruding portion>

[0043] Since even slight differences in the shape and arrangement of the protrusions can affect the amount of spin and make it difficult to achieve the objectives of the present invention, the protrusions must be processed using a method that allows for high-precision machining. There are no particular limitations on the specific machining method, but in this embodiment, laser milling is extremely preferred as a method for machining the protrusions and their arrangement.

[0044] Laser milling allows for the creation of fine surface textures on a fixed workpiece by applying a laser beam to the material, causing it to melt or evaporate. Because the laser beam can be controlled with extreme precision, highly accurate processing is possible. The golf club used in the verification results described later was also laser-milled. Here, the diameter of the laser beam used in laser milling is 0.07 millimeters, and the laser output wattage is 100 watts.

[0045] Another method, for example, is cutting milling. Cutting milling is a method of cutting a fixed workpiece by applying a rotary cutting tool such as a milling cutter or end mill to it, and it is possible to create fine grooves and irregularities on the surface of the material. However, with cutting milling, it takes several to more than 10 times longer to create a nice frustoconical shape compared to simple vertical cutting, which may result in a higher cost. In contrast, laser milling can create a nice frustoconical shape without significantly changing the time. In other words, in this embodiment, laser milling is the most suitable method. Another example is sandblasting. This method involves using compressed air to rapidly blast abrasive materials (such as sand, alumina, or glass beads) onto the surface of metal or other materials, creating fine irregularities on the surface. Another example is dry etching. This method uses a gas (such as plasma, reactive gas, or ion beam) to remove material such as metal, creating fine irregularities on the surface. However, these are merely examples and not the only methods that can be used.

[0046] <Embodiment 1 Configuration: Radius of curvature of the cross-sectional portion of the convex shape of the frustoconical shape>

[0047] Incidentally, even when using high-precision machining methods such as laser milling, the boundary between the apex and the side surface of the convex part of a frustoconical shape is usually not a perfectly edge shape due to machining limitations, but rather a somewhat rounded shape. Figure 4 shows an example in which a rounded shape 0403 is formed between the apex 0402a and the side surface 0402b of the frustoconical convex portion 0401. In this case, the preferred range for the cross-sectional radius of curvature r is 0.005 millimeters or less. The cross-sectional radius of curvature of the frustoconical convex portion used in the verification results described later is also 0.005 millimeters or less. For example, if the cross-sectional radius of curvature r exceeds 0.005 millimeters, the shape of the convex portion will approach a semi-convex lens shape rather than a frustoconical shape, and there is a risk that it will not be possible to guarantee that a suitable amount of spin can be obtained by making the convex portion shape a frustoconical shape.

[0048] <Effect of Embodiment 1>

[0049] Based on the above, the present invention provides a golf club with grooves or irregularities on the face surface that result in virtually no difference in backspin amount, regardless of whether the club is dry or wet.

[0050] <Embodiment 2 (mainly corresponding to claims 3, 4, and 5)>

[0051] <Overview of Embodiment 2>

[0052] The golf club of this embodiment is based on the configuration of the golf club of Embodiment 1, but the shape of the convex portion of the face is a frustoconical shape, and its dimensions are within a predetermined range.

[0053] <Embodiment 2 Configuration: Dimensions of the convex part of the frustoconical shape>

[0054] The configuration of the golf club in this embodiment is basically the same as that of the golf club in Embodiment 1. That is, the shape of the convex portion on the face of the golf club head in this embodiment is the same frustoconical shape as in Embodiment 1. Furthermore, the diameter of the base of the frustoconical shape, the diameter of the apex, the distance between adjacent frustoconical shapes, and the height of the frustoconical shape are of suitable dimensions.

[0055] An example of the shape of the convex part of a frustoconical shape has already been shown in Figures 1 to 4.

[0056] Figure 5 shows an example of an enlarged view and a cross-sectional view of the shape of the golf club according to this embodiment.

[0057] <Embodiment 2 Configuration: Dimensions of the convex part of the frustoconical shape, Diameter of the base>

[0058] As shown in Figure 5(a), the diameter d1 of the base surface 0501a of the frustoconical convex portion 0501 is in the range of 0.3 mm to 0.5 mm, and more preferably in the range of 0.35 mm to 0.45 mm. This value is based on the verification results described later, and the same applies to the other dimensions described below.

[0059] <Embodiment 2 Configuration: Dimensions of the convex part of the frustoconical shape, diameter of the apex>

[0060] Similarly, as shown in Figure 5(a), the diameter d2 of the apex 0502b of the frustoconical convex portion 0502 ranges from 0.16 millimeters to 0.22 millimeters.

[0061] <Embodiment 2 Configuration: Dimensions of the convex part of the frustum of a cone, distance between adjacent frustums of cones>

[0062] Figure 6 shows an example of the adjacent frustum of cone distance in the golf club of this embodiment. The adjacent frustum of cone distance is between the centers c1 and c2 of the apex of adjacent frustums of cones, and is in the range of 0.35 millimeters to 0.75 millimeters, more preferably in the range of 0.45 millimeters to 0.65 meters. This is because if the adjacent frustum of cone distance is too narrow, the drainage effect decreases, and conversely, if it is too wide, the number of frustums and the area of ​​the flat portion decrease, resulting in a decrease in frictional force.

[0063] <Embodiment 2 Configuration: Dimensions of the convex part of the frustoconical shape: height>

[0064] Furthermore, as shown in Figure 5(b), the height h of the frustoconical protrusion 0503 is in the range of 0.020 mm to 0.025 mm. This is because the Rules of Golf (R&A) stipulate that the unevenness of the flat area between a scoreline groove and an adjacent scoreline groove must be 0.025 mm or less, so the range of 0.020 mm to 0.025 mm was chosen to maximize the drainage effect.

[0065] <Effects of Embodiment 2>

[0066] Based on the above, the present invention provides a golf club with grooves and irregularities on the face surface that have a shape that results in virtually no difference in spin rate whether the club is dry or wet, and with more suitably designed protrusions. ?

[0067] <Embodiment 3 (mainly corresponding to claim 6)>

[0068] <Overview of Embodiment 3>

[0069] The golf club of this embodiment is based on the configuration of the golf club of Embodiment 1 or Embodiment 2, but the face material is made of metal.

[0070] <Embodiment 3 Configuration: Face Material>

[0071] The configuration of the golf club in this embodiment is basically the same as that of the golf club in Embodiment 1 or Embodiment 2. However, the golf club in this embodiment has a metal face for the club head.

[0072] As already mentioned in Embodiment 1, metal is often used as the material for the face of a golf club head. One reason for this is that it is easy to form precise and fine grooves and irregularities using laser milling and other processes. In addition, due to the characteristics of golf clubs, high strength, high rebound, precision, feel, and spin performance are important, so metal is often used as the material for the face.

[0073] Examples of metals that can be used include titanium alloys, forged titanium, maraging steel, carbon composite materials, stainless steel, titanium, soft iron (forged), and carbon steel. For example, titanium alloys (e.g., Ti-6A1-4V) are the most commonly used metals, being lightweight, strong, and allowing for a thinner face to improve rebound performance. For example, forged titanium (e.g., β-titanium) has even greater strength and responsiveness than usual, and has the characteristic of widening the sweet spot on the club head face. For example, maraging steel is heavier than titanium, but it is cheaper and provides a moderate rebound feel, so it is often used in entry-level models and some small-headed clubs. For example, carbon composite materials have the characteristics of being lightweight and offering a high degree of design flexibility. For example, stainless steel (e.g., 17-4 stainless steel) offers good cost performance and has a slightly harder feel, but it is often used in mid-range to entry-level models. For example, titanium is often used in higher-end models, allowing for larger heads and higher rebound. For example, soft iron (e.g., S20C, S25C, etc.) is a staple for forged irons, and it can improve the feel of the ball and spin performance. Furthermore, 8620 carbon steel offers a soft feel and strong spin performance. It is also easy to process, allowing for precise milling and grooving of the clubface. While some club faces are plated to prevent corrosion and scratches, this process increases the hardness of the clubface. Therefore, players who prefer a softer feel (especially professionals or advanced amateurs) tend to prefer clubs without plating. However, this is not limited to these examples.

[0074] Thus, in this embodiment, by using metal as the material for the face of the club head, it is possible to perform precise and fine processing, ensure a more stable spin rate, and thereby more favorably achieve the objective of the present invention.

[0075] <Embodiment 3 Effects>

[0076] Based on the above, the present invention provides a golf club with grooves or irregularities on the face surface that result in virtually no difference in spin rate whether the club is dry or wet, using a more suitable metal material.

[0077] <Regarding the verification results>

[0078] The applicant conducted actual verifications on several items (perspectives) to demonstrate that a golf club that can maintain virtually the same spin rate in both dry and wet conditions is preferable, specifically one with more than 2000 convex portions arranged in a roughly regular hexagonal shape on the face, where the convex portions are frustoconical. The results of these verifications are described below.

[0079] <Preparing for verification>

[0080] <Preparation for verification: Making a test golf club>

[0081] To conduct this test, we created four different types of golf clubs. Figure 9 shows the types of golf clubs used in the verification. As shown in Figure 9(a), a gap wedge (GW) was chosen as a representative example of a golf club, and the overall shape, dimensions, and material of the club head 0901 of the gap wedge (GW) were all made identical. In addition, the number of scoreline grooves 0903 provided on the club head 0901, the groove width, and groove depth were all made identical in accordance with the Rules of Golf (R&A). Then, four types of golf clubs were manufactured in total: one type with no protrusions formed in the land area 0904, which represents the smooth area between a scoreline groove and an adjacent scoreline groove on the face, and three types with protrusions formed by laser milling or other processes. Figures 9(b) through (e) are enlarged views of the area enclosed by the rectangle 0902 in Figure 9(a), that is, the region where the land portion 0904 is the central part and scoreline grooves exist on both sides of it. Here, Figure 9(b) shows a golf club in which no protrusions have been machined onto the land portion 0904 of the face (hereinafter referred to as "unmachined"). Furthermore, Figure 9(c) shows a golf club (hereinafter referred to as "PTG1") in which a truncated pentagon shape is arranged in a regular pattern as a convex portion on the land portion 0904 of the face. Furthermore, Figure 9(d) shows a golf club (hereinafter referred to as "PTG2") in which frustum pentagonal shapes are arranged in a staggered pattern as protrusions on the land portion 0904 of the face. Furthermore, Figure 9(e) shows a golf club (hereinafter referred to as "WCF") in which frustoconical shapes are arranged in a staggered pattern as protrusions on the land portion 0904 of the face.

[0082] <Preparation for verification: Creation of a test machine>

[0083] Furthermore, I created a test machine to measure various parameters, namely (1) ball speed, (2) launch angle, (3) launch direction, (4) spin rate, (5) maximum height, and (6) carry distance, by actually hitting balls with the four types of golf clubs mentioned above. This is because it is practically extremely difficult for a human golfer to repeatedly perform test swings with the same conditions accurately and without fatigue each time.

[0084] <Preparation for verification: Specific examples of test machines>

[0085] Figure 10 shows the front and side views of the test machine that I made myself for this verification. Figure 10(a) shows a front view when facing the test machine 1000, showing the shaft 1002 swinging up to an angle of approximately 160 degrees around the central axis A1001. This indicates that the test will be conducted with a so-called half swing (half shot), not a full swing (full shot). The golf club head 0901 shown in Figure 9(a) (omitted in Figure 10) will be attached to the tip of this shaft. The shaft material can be steel (e.g., carbon steel or stainless steel), carbon (e.g., carbon fiber molded with resin), or composite material (e.g., a hybrid structure combining steel and carbon). While any material shaft can be selected, for this verification, we decided to use a steel shaft because it is compatible with gap wedges (GW), generates a lot of spin, is easy to control, has a stable trajectory, and is highly durable. Generally, the shaft length of a gap wedge (GW) is around 90 centimeters, so we decided to use a shaft of that length for this verification. Furthermore, it is equipped with a swing angle adjustment plate 1003, which guides the shaft 1002 to be swung from its lowest point of 0 degrees to a maximum of 160 degrees. In addition, it is equipped with a height adjustment function 1004 so that it can be set according to the length of the shaft. Generally, the driver has the longest shaft, the shafts of irons get shorter as the club number increases, and the shafts of wedges also get shorter from PW to LW, so the height adjustment function 1004 is necessary to compensate for that difference. Figure 10(b) shows the left side view of the demo unit 1000, that is, the view from the direction from which the ball is coming. The demo unit 1000 also employs the forward tilt angle adjustment function 1108 to match the angle between the vertical direction and the shaft when a human golfer actually holds a golf club and swings it. In other words, the angle between the center line of the golf club shaft and the ground is called the "lie angle," and generally, the lie angle increases as the number of the golf club increases (as the club gets shorter). Therefore, the forward tilt angle adjustment function 1108 is adopted so that the lie angle can be adjusted for each golf club being used. It should be noted, and this is a repetition, that in Figure 10, the club head is shown with a dotted line and is omitted from the illustration.

[0086] In addition to the aforementioned test machines, a portable ball flight measurement device (Garmin® "Approach R10") was used to measure ball speed, launch angle, launch direction, spin rate, maximum height, and carry distance.

[0087] Furthermore, we will explain a practical example of its use (in the case of a wedge shot). Regarding installation, for radar-type measuring devices, the main unit should be placed 2-3 meters behind the batting cage and aligned straight with the direction of the hit. On the other hand, for camera-type measuring devices, the main unit should be placed to the side or diagonally in front of the ball, and the ball should be placed in the sensor area. For calibration (initial setup), you will need to input wind speed and altitude if using it outdoors. If using it indoors, you may also need to input the distance to the screen or net. For hitting a wedge shot, the ball's trajectory is measured from immediately after impact. Radar-type measuring devices track the entire ball as it flies. On the other hand, camera-type measuring devices simulate the trajectory from various data immediately after impact (speed, launch angle, launch direction, spin rate, etc.). Regarding data display, the measuring device's monitor and smartphone app instantly display information such as "ball speed, launch angle, launch direction, spin rate, carry distance, and highest point reached."

[0088] Figure 11 is an enlarged side view of the test machine shown in Figure 10(b). As can be seen from this diagram, the demo machine 1100 consists of an electromagnet 1101 attached to the aluminum frame 117 of the demo machine body, a steel plate 1102 attached to a rotatable pole on the golf club side opposite to the electromagnet, and a golf club consisting of a shaft 1103 and a club head 1104. Here, an "electromagnet" refers to a device that generates a magnetic field by passing an electric current through a conductive coil, and the magnetic flux density can be increased by using a magnetic material (iron core). The magnetic force can be generated (ON) and extinguished (OFF) by controlling the current, and it refers to devices that are widely used for controlling moving parts and operating electrical equipment. Furthermore, the operation of the demo unit 1100 will be explained as follows. Firstly, by passing an electric current through the electromagnet 1101 attached to the aluminum frame side of the test machine, a magnetic field is generated, causing it to function as a magnet. Secondly, the iron plate 1102 opposite the electromagnet 1101 is attracted to it and comes into contact with it. Thirdly, while the electromagnet 1101 and the iron plate 1102 remain in contact, the golf club, consisting of the shaft 1103 and the club head 1104, is lifted and rotated from 0 degrees, which is vertically downward from the test machine, to a predetermined swing angle (approximately 160 degrees in this case), and then held in that position. Fourthly, by stopping the current flowing through the electromagnet 1101, the magnetic field of the electromagnet 1101 disappears, the iron plate 1102, which was previously in contact with the electromagnet 1101, separates from the electromagnet 1101, and the golf club, consisting of the shaft 1103 and club head 1104, falls under its own weight. In other words, the golf club is swung with the central axis A1001 in Figure 10(a) as the axis of rotation. At that time, the total value of the shaft 1103, club head 1104, iron plate 1102, and the weight 1106 (in this case, 1 kg) attached to the lower end of a pole-shaped structure with the iron plate attached to the upper end becomes the load. Fifth, the golf club is swung, and the club head 1104 launches the ball 1105, which is placed vertically below the test machine 1100. The golf ball used here is a TaylorMade (trademark) BURNER (distance type 2-piece ball). At this time, the values ​​of the above items are recorded and accumulated using the measuring instrument described above, and these values ​​are compiled into a curve graph and displayed on a screen or similar device for evaluation. Each golf club was tested 100 times. This was because we believe that a sufficient number of tests are necessary to clearly see the differences between each club.

[0089] <Preparing for verification: An example of how to interpret verification data>

[0090] Figure 12 shows an example of how to interpret the verification data. In this verification, as mentioned above, we measured and recorded the values ​​for six items: (1) ball speed, (2) launch angle, (3) launch direction, (4) spin rate, (5) highest point reached, and (6) carry distance. We also verified whether the measured values ​​were stable and consistent. In other words, we graphed the distribution of the measured values ​​for each item to check for any variation and made an evaluation. Specifically, as shown in Figure 12(a), if the measured values ​​show only one peak and no other peaks appear in the curve graph, it can be said that the golf club is very stable, with little to no variation, meaning it has good repeatability and reproducibility. On the other hand, as shown in Figure 12(b), if the curve graph shows peaks not just in one place but in multiple places, it can be said that the golf club is very unstable and has a large variability, meaning it is a golf club with poor repeatability and reproducibility. From this point forward, in Figures 13 to 30 (excluding Figures 13, 16, 19, 22, 25, and 28), when the measured values ​​of each golf club are plotted on a curve graph for comparison, the vertical axis represents the launch angle (deg), and the horizontal axis represents the measured value of that item. Furthermore, in this verification, the "evaluation score" was determined as follows: a score of "2" was given if there was no characteristic difference in the curve graph between dry and wet conditions (they appeared to be almost the same), meaning that the club was stable, had little to no variation, and good repeatability and reproducibility; a score of "1" was given if there was a slight difference in the curve graph between dry and wet conditions, meaning that the club was relatively stable, had little variation, and had relatively good repeatability and reproducibility; and a score of "0" was given if there was a clear characteristic difference in the curve graph between dry and wet conditions, meaning that the club was very unstable, had a lot of variation, and had poor repeatability and reproducibility. Finally, the golf club with the highest cumulative score was evaluated as the optimal golf club.

[0091] <Verification Results (1) Specific Examples of Ball Speed ​​(m / s)>

[0092] Figure 13 schematically illustrates the verification data, "(1) Ball Speed ​​(m / s)". In other words, the initial velocity of the launched ball is measured as ball speed.

[0093] Figure 14 shows a comparison of four types of golf clubs in dry and wet conditions, based on the verification data "(1) Ball Speed ​​(m / s)". As can be seen from this diagram, the three types other than "WCF"—namely "unprocessed," "PTG1," and "PTG2"—show clearly different waveforms in dry and wet conditions. In other words, these three types of golf clubs are unstable and have a large degree of variability. On the other hand, "WCF" shows almost the same waveform in both dry and wet conditions, indicating that it is stable and has little to no variation.

[0094] Figure 15 shows a comparison of the verification data, "(1) Ball Speed ​​(m / s)," for each of the four types of golf clubs, comparing dry and wet conditions. As can be seen from this diagram, all four types of golf clubs show relatively stable performance when dry. However, when wet, the three types of golf clubs other than "WCF"—namely "unprocessed," "PTG1," and "PTG2"—all show two peaks, indicating instability and high variability. On the other hand, for "WCF," there is only one peak in both dry and wet conditions, indicating stability and little to no variation. More specifically, the ball speed of "WCF" is stable in the range of approximately 6.5 to 7.5 m / s in dry conditions and stable in the range of approximately 6.0 to 7.0 m / s in wet conditions. In other words, "WCF" is the most stable and least varied (or has little to no variation) in terms of ball speed, meaning it has excellent repeatability and reproducibility. Based on the above results, the evaluation scores were set as follows: "WCF" received 2 points, while "No Processing," "PTG1," and "PTG2" received 0 points.

[0095] <Verification Results (2) Specific Examples of Launch Angle (deg)>

[0096] Figure 16 schematically illustrates the verification data, "(2) Launch Angle (deg)". In other words, the launch angle is measured as the angle between the initial trajectory of the launched ball and the ground.

[0097] Figure 17 shows a comparison of four types of golf clubs in dry and wet conditions for the verification data "(2) Launch angle (deg)". As can be seen from this diagram, the two types other than "WCF" and "unprocessed," namely "PTG1" and "PTG2," show clearly different waveforms in dry and wet conditions. In other words, these two types of golf clubs are unstable and have a large degree of variability. On the other hand, for "WCF" and "unprocessed," the waveforms are almost identical in both dry and wet conditions, indicating stability and minimal (or no) variation.

[0098] Figure 18 shows a comparison of the verification data, "(2) Launch Angle (deg)," for each of the four types of golf clubs, comparing dry and wet conditions. As can be seen from this figure, all four types of golf clubs show stable performance when dry, but when wet, the two types of golf clubs other than "WCF" and "unprocessed," namely "PTG1" and "PTG2," both show a significant drop in performance. Furthermore, the peak values ​​tend to be significantly lower compared to the case of "WCF," indicating instability and high variability. In contrast, for the "no processing" case, the waveform of the curve graph is almost the same for both dry and wet conditions, but the peak value tends to be lower than that of "WCF". On the other hand, the waveform of the "WCF" is almost the same whether dry or wet, and it can be said to be stable and have little to no variation compared to other golf clubs. More specifically, the launch angle of the "WCF" is stable in the range of 20 to 25 degrees when dry, and also stable in the range of 20 to 25 degrees when wet. In other words, the "WCF" was found to be the most stable and has little to no variation in terms of launch angle, meaning it has excellent repeatability and reproducibility. Based on the above results, the evaluation scores were set as follows: "WCF" = 2 points, "No processing" = 1 point, and "PTG1" and "PTG2" = 0 points.

[0099] <Verification Results (3) Specific Examples of Launch Direction (deg)>

[0100] Figure 19 is a schematic diagram illustrating the verification data "(3) Launch direction (deg)". As shown in this figure, the target line (launch direction) is set to 0 degrees, and the measurement is taken as "-○○ degrees" when the launched ball flies in a slice (right) direction, and as "+△△ degrees" when the launched ball flies in a hook (left) direction. As mentioned earlier in this specification, this explanation is given because the present invention assumes that a right-handed golfer is using a right-handed golf club. If a left-handed golfer is using a left-handed golf club, it should be noted that the launch direction will be reversed left and right.

[0101] Figure 20 shows a comparison of four types of golf clubs in dry and wet conditions for the verification data "(2) Launch direction (deg)". As shown in this figure, the "no processing" waveform is slightly hooked (to the left) in both dry and wet conditions, but shows almost the same waveform, indicating stability and little to no variation. On the other hand, the "PTG1," "PTG2," and "WCF" clubs exhibit clearly different waveforms, with the launch direction fluctuating left and right between dry and wet conditions. In other words, these three types of golf clubs are unstable and exhibit a large degree of variability.

[0102] Figure 21 shows a comparison of dry and wet conditions for each of the four types of golf clubs, specifically for the verification data "(3) Launch direction (deg)". As shown in this figure, the "no processing" case shows a slight bias towards the hook (left) direction (around +5) in both dry and wet conditions, but since it exhibits almost the same waveform, it can be said to be stable and have little to no variation. On the other hand, "PTG1," "PTG2," and "WCF" show a bias towards a slice (right) direction (around -5 degrees to 0 degrees) when dry, and a bias towards a hook (left) direction (around 0 degrees to +5 degrees) when wet. Therefore, overall, they can be said to be unstable and have a large degree of variability. In other words, it was found that "no processing" was the most stable and had little to no variation in terms of the punching direction, meaning it had excellent repeatability and reproducibility. Based on the above results, the evaluation scores were set as follows: "No processing" received 2 points, while "PTG1", "PTG2", and "WCF" received 0 points.

[0103] <Verification Results (4) Specific Examples of Spin Rate (rpm)>

[0104] Figure 22 is a schematic diagram illustrating the verification data "(4) Spin Amount". As shown in this diagram, when the club head face and the ball collide, the frictional resistance between them causes spin in the opposite direction to the ball's flight path, so-called backspin, and the initial number of rotations of this backspin is measured as "Spin Amount (rpm)".

[0105] Figure 23 shows a comparison of four types of golf clubs in dry and wet conditions, based on the verification data "(4) Spin rate (rpm)". As shown in this figure, the waveforms for "No Processing," "PTG1," and "PTG2" (excluding "WCF") differ between dry and wet conditions. In particular, the waveforms in the wet conditions are significantly distorted, indicating instability and high variability. On the other hand, while there are slight differences in the waveform between dry and wet conditions for "WCF," overall it can be said to be stable and have little to no variation.

[0106] Figure 24 shows a comparison of the verification data "(4) Spin rate (rpm)" for each of the four types of golf clubs, comparing dry and wet conditions. As shown in this diagram, there are significant differences in the waveforms of "PTG1" and "PTG2" between dry and wet conditions, indicating that the amount of ball spin is significantly lower in wet conditions than in dry conditions. In other words, "PTG1" and "PTG2" are unstable and highly variable. On the other hand, for the "unprocessed" sample, there are slight differences in the waveform between dry and wet conditions, and there are also slight differences in the spin rate between dry and wet conditions, but it can be seen that the absolute value of the spin rate is lower compared to the "WCF" sample. In other words, although there are some differences compared to the "WCF" sample, the "unprocessed" sample is relatively stable and has little to no variation. In contrast, while there are slight differences in the waveform between dry and wet conditions for "WCF," and slight differences in spin rate between dry and wet conditions (a phenomenon where the spin rate is lower in wet conditions compared to dry conditions can be observed), the absolute value of the spin rate is the highest, indicating stability and little (or no) variation. More specifically, it can be seen that it is stable in the range of approximately 3300-3400 rpm in dry conditions and approximately 3100-3400 rpm in wet conditions. In other words, "WCF" was found to be the most stable and consistent (or with little to no variation) in terms of spin rate, meaning it exhibited excellent repeatability and reproducibility. Based on the above results, the evaluation scores were set as follows: "WCF" = 2 points, "No processing" = 1 point, and "PTG1" and "PTG2" = 0 points.

[0107] <Verification Results (5) Specific Examples of Maximum Reach (m)>

[0108] Figure 25 schematically illustrates the verification data, "(5) Highest point reached (m)". In other words, the highest point reached is calculated as the point at which the ball reaches its highest point from the time it is launched from a stationary position at a predetermined speed and launch angle until it eventually falls to the ground.

[0109] Figure 26 shows a comparison of four types of golf clubs in dry and wet conditions for the verification data "(5) Maximum reach (m)". As shown in this diagram, the waveforms for each golf club are more concentrated in one place when wet than when dry, indicating greater stability. Of these, the "WCF" waveform is particularly high and stable, with little to no variation, suggesting good repeatability and reproducibility.

[0110] Figure 27 shows a comparison of the verification data "(5) Maximum reach (m)" for each of the four types of golf clubs in dry and wet conditions. As shown in this figure, the waveform of "PTG2" is almost the same shape in both dry and wet conditions, and there is little difference in the peak peak between the dry and wet conditions. In other words, "PTG2" can be said to be stable and has little to no variation. On the other hand, "WCF" exhibits slightly different waveforms in dry and wet conditions, a slightly larger difference in the maximum height reached in dry and wet conditions compared to "PTG2," and a greater launch angle in wet conditions than in dry conditions. In other words, "WCF" is the second most stable and least variable after "PTG2." More specifically, the maximum height reached by "WCF" is approximately 3.5-4.5m in dry conditions and approximately 0.30-0.35m in wet conditions, indicating that it is slightly lower in wet conditions than in dry conditions. In contrast, while there is almost no difference in the highest point reached in the dry and wet conditions for "No Processing" and "PTG1," the waveforms differ significantly between the dry and wet conditions, and the launch angle in the wet condition is significantly lower than in the dry condition. In other words, "No Processing" and "PTG1" show a large difference in waveforms between the dry and wet conditions, indicating that they are unstable and have high variability. In other words, "PTG2" was found to be the most stable and least varied (or with minimal variation) in the highest performance category, meaning it had excellent repeatability and reproducibility. Based on the above results, the evaluation scores were set as follows: "PTG2" received 2 points, "WCF" received 1 point, and "No Processing" and "PTG1" received 0 points.

[0111] <Verification Results (6) Specific Examples of Carry Distance (yd)>

[0112] Figure 28 schematically illustrates the verification data, "(6) Carry distance (yd)". In other words, it calculates the carry distance (excluding the ball's roll, etc.) from the position where the ball was stationary until it hit the ground.

[0113] Figure 29 shows a comparison of four types of golf clubs in dry and wet conditions for the verification data "(6) Carry distance (yd)". As shown in this figure, "WCF" shows almost no difference between the dry and wet waveforms, and there is no significant difference, indicating stability and little (or no) variation, meaning it has good repeatability and reproducibility. On the other hand, "No Processing," "PTG1," and "PTG2" all show differences between the dry and wet waveforms, and the differences are large, indicating instability and high variation.

[0114] Figure 30 shows a comparison of the verification data "(6) Carry distance (yd)" for each of the four types of golf clubs, comparing dry and wet conditions. As shown in this diagram, the waveform of "PTG1" is almost the same shape in both dry and wet conditions, and there is also almost no difference in carry distance between dry and wet conditions. In other words, "PTG1" can be said to be stable and has little to no variation. On the other hand, the "WCF" exhibits almost the same waveform shape in both dry and wet conditions, and although there is a slight difference in carry distance between dry and wet conditions, it is the second most stable after the "PTG1," and can be said to have little to no variation. More specifically, the carry distance of the "WCF" is approximately 3.5 to 4.5 yards in dry conditions and approximately 3.0 to 4.0 yards in wet conditions, indicating that it has the characteristic of being slightly shorter in wet conditions than in dry conditions. In contrast, the "unprocessed" and "PTG2" models exhibit significantly different waveforms in dry and wet conditions, and the difference in carry distance between dry and wet conditions is also larger compared to the "WCF" model. Therefore, they can be considered unstable and highly inconsistent. In other words, the "PTG1" proved to be the most stable and consistent (or with little to no variation) in terms of carry distance, meaning it had excellent repeatability and reproducibility. Based on the above results, the evaluation scores were set as follows: "PTG1" was 2 points, "WCF" was 1 point, and "No Processing" and "PTG2" were 0 points.

[0115] <Verification Results: Overall Evaluation>

[0116] Finally, adding up the evaluation values ​​for each of the above items, the overall evaluation is as follows. "WCF" = 8 points "No processing" = 4 points "PTG1" = 2 points "PTG2" = 2 points In other words, of the four types of golf clubs tested, the "WCF" (which has more than 2000 convex parts arranged in a roughly hexagonal shape on the face, and the convex parts are frustoconical) was clearly the most stable and had no (or very little) variation, meaning it had excellent repeatability and reproducibility. Therefore, based on the objective and specific verification data shown in the above verification results, the present invention provides a golf club with grooves and irregularities on the face surface that result in virtually no difference in backspin amount, regardless of whether the club is dry or wet, thus achieving an objective and remarkable effect.

[0117] While the verification results were measured using a GW (gap wedge) as a representative example, the present invention can also be applied to other wedges such as PW (pitching wedge), SW (sand wedge), and LW (lob wedge). This makes it possible to reliably aim for the pin on the green and stop the ball from close distances around the green, regardless of whether the green is dry or wet, which can be a major factor in improving your score. [Explanation of Symbols]

[0118] Club head 0100 Face surface 0101 Rectangle 0102 Convex part 0103 Circular 0104 Base of the convex part when it is shaped like a truncated cone 0105 The top surface when the convex part is shaped like a truncated cone 0106 Side view when the convex part is frustoconical 0107

Claims

1. A wedge with over 2,000 protrusions arranged in a roughly hexagonal pattern on its face.

2. The wedge according to claim 1, wherein the convex portion is frustoconical.

3. The wedge according to claim 2, wherein the base of the frustum of the cone has a diameter in the range of 0.3 mm to 0.5 mm, and the apex of the frustum of the cone has a diameter in the range of 0.16 mm to 0.22 mm.

4. The wedge according to claim 3, wherein the distance between adjacent frustums of cones is in the range of 0.35 mm to 0.75 mm between the centers of the apex faces.

5. The wedge according to any one of claims 2 to 4, wherein the height of the frustoconical shape is in the range of 0.020 mm to 0.025 mm.

6. The wedge according to any one of claims 1 to 4, wherein the material of the face surface is metal.

7. The wedge according to claim 5, wherein the material of the face surface is metal.

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