Golf club faces with multiple durometer hardness levels

Abstract

This specification describes embodiments of a putter-type clubhead featuring a face insert having multiple durometer hardnesses. The face insert achieves a durometer hardness variation profile through three or more discrete regions or zones, with the central zone having the lowest hardness and the consecutive outer zones having higher hardness than the adjacent inner zones. The face insert normalizes the smash factor across the entire face by strategically reducing the smash factor in the center of the face, making it easier to predict the ball's roll distance on mishits.

Description

【Technical Field】 【0001】 (Cross-reference related to priority) This application claims the benefit of U.S. Provisional Application No. 63 / 506,014, filed Jun. 2, 2023, the entire contents of which are incorporated herein by reference. 【0002】 The present disclosure generally relates to golf club heads, and more particularly to putter-type golf club heads having a face insert. Background Art 【0003】 Typically, golfers attempt to make a consistent swing, so the same part of the club hits the ball with each swing. This tendency is particularly pronounced in putts where accuracy is important. Depending on the location on the putter-type club head that strikes the golf ball, the amount of energy transmitted from the putter head to the golf ball at the first contact can vary. Specifically, variations in the position on the striking face can cause variations in the ball speed on the striking face, potentially resulting in an unexpected distance for the putt. Conventional putter-type golf clubs do not provide sufficient compensation for off-center hits. 【0004】 To facilitate the description of the embodiments, the following drawings are provided. 【Brief Description of the Drawings】 【0005】 [Figure 1] Front perspective view of a putter having a face insert according to an aspect of the present invention. [Figure 2] Exploded assembly view of the putter of FIG. 1. [Figure 3] Top cross-sectional view of the face insert of the putter of FIG. 1. [Figure 4] Another top cross-sectional view of the face insert of the putter of FIG. 1. [Figure 5]Figure 1 is a front view of the putter, with the faceplate of the face insert removed. [Figure 6] This is a front view of another embodiment of a golf club equipped with a face insert according to an aspect of the present invention, with the face plate of the face insert removed. [Figure 7] This is a front view of another embodiment of a golf club equipped with a face insert according to an aspect of the present invention, with the face plate of the face insert removed. [Figure 8] This is a front view of another embodiment of a golf club equipped with a face insert according to an aspect of the present invention, with the face plate of the face insert removed. [Figure 9] This is a front view of another embodiment of a golf club equipped with a face insert according to an aspect of the present invention, with the face plate of the face insert removed. [Figure 10] This is a front view of another embodiment of a golf club equipped with a face insert according to an aspect of the present invention, with the face plate of the face insert removed. [Figure 11] This is a front view of another embodiment of a golf club equipped with a face insert according to an aspect of the present invention, with the face plate of the face insert removed. [Figure 12] This is a front view of another embodiment of a golf club equipped with a face insert according to an aspect of the present invention, with the face plate of the face insert removed. [Figure 13] This is a front view of another embodiment of a golf club equipped with a face insert according to an aspect of the present invention, with the face plate of the face insert removed. [Figure 14] This graph shows the relationship between the smash factor and the impact position of a putter equipped with the face insert according to the present invention. [Figure 15]This graph shows the relationship between the smash factor and the impact position of a putter equipped with the face insert according to the present invention. [Modes for carrying out the invention] 【0006】 This specification describes a putter face that ensures consistent ball velocity across the entire face when striking a golf ball in a putting stroke. The putter face exhibits relatively low energy transfer near the center, with gradually increasing energy transfer as you move away from the center. This results in uniform ball velocity across the entire face, making distance easier to predict and reducing mishits. The putter face achieves consistent ball velocity by utilizing a face insert with multiple durometer hardness levels. 【0007】 (definition) To ensure conciseness and clarity of explanation, the figures show the general configuration of the structure, and descriptions and details of well-known features and technologies may be omitted to avoid unnecessarily complicating the invention. In addition, elements in the figures are not necessarily drawn to actual size. For example, to facilitate understanding of embodiments of the invention, the dimensions of some elements in the figures may be drawn larger than those of others. The same reference numerals in different figures indicate the same element. 【0008】 Where terms such as “first,” “second,” “third,” and “fourth” are used in this specification and in the claims, these terms are used to distinguish similar elements and do not necessarily represent a specific order or chronological order. It should be understood that such terms are interchangeable under appropriate circumstances, for example, when the embodiments described herein can operate in an order other than that shown herein or otherwise described. Furthermore, the terms “includes” and “possesses,” and their variations, are intended to cover non-exclusive inclusion, and a process, method, system, article, device, or apparatus comprising a list of elements is not necessarily limited to those elements and may include elements not explicitly enumerated, or other elements inherent to such process, method, system, article, device, or apparatus. 【0009】 Where terms such as “left,” “right,” “front,” “rear,” “up,” “down,” “above,” and “below” are used in this specification and in the claims, these terms are used for explanatory purposes and are not necessarily intended to describe permanent relative positions. It should be understood that these terms are interchangeable in appropriate circumstances where embodiments of the present invention described herein can operate in orientations other than those illustrated or otherwise described herein. 【0010】 The terms "to connect," "connected," "linked," and "connected" should be interpreted broadly and refer to the electrical, mechanical, and / or otherwise connected relationship between two or more elements or signals. 【0011】 As used herein, the term "striking face" refers to the front surface of the club head configured to strike a golf ball. The term "striking face" is interchangeable with the term "face." 【0012】 As used herein, the terms “geometric center point” or “geometric center” may refer to the geometric center point of the outer perimeter of the striking face, and the midpoint of the face height of the striking face. In the same or different examples, the geometric center point may be the center of the engineered impact zone that can be formed by the groove region on the striking face. Alternatively, the location of the geometric center point of the striking face may be determined according to the definition of a golf governing body such as the United States Golf Association (USGA). 【0013】 As used herein, the term “ground surface” may refer to a reference surface related to the surface on which the golf ball is placed. The ground surface may be a horizontal surface in contact with the sole of the club at the address position. 【0014】 As used herein, the term "loft plane" may refer to a reference plane tangent to the geometric center point of the striking face. 【0015】 As used herein, the term "loft angle" may refer to the angle measured between the loft plane and the XY plane perpendicular to the ground plane and extending in the heel-toe direction. 【0016】 In some embodiments, the term “putter” may refer to a putter-type clubhead with a loft angle of less than 10 degrees. In many embodiments, the loft angle of a putter may be 0–5 degrees, 0–6 degrees, 0–7 degrees, or 0–8 degrees. For example, the loft angle of a clubhead may be less than 10 degrees, less than 9 degrees, less than 8 degrees, less than 7 degrees, less than 6 degrees, or less than 5 degrees. Furthermore, for example, the loft angle of a clubhead may be 0 degrees, 1 degree, 2 degrees, 3 degrees, 4 degrees, 5 degrees, 6 degrees, 7 degrees, 8 degrees, 9 degrees, or 10 degrees. A putter-type golf clubhead may be a blade putter, a mid-mallet putter, or a mallet putter. 【0017】 The putter described herein includes a face insert having a plurality of durometer hardnesses, and the face insert has regions of different hardnesses. These regions are strategically arranged on the striking face so that the ball speed is stable. When the hardness of the striking face is high, the rolling distance is longer compared to the case of low hardness. Therefore, in the striking face according to an aspect of the present invention, by providing a low-hardness region near the center portion, energy transfer is reduced (or the center impact is "blunted"), and a region with gradually increasing hardness is provided toward the end / peripheral region of the striking face to equalize the energy loss during an off-center hit. With the plurality of durometer hardness / hardness profiles, the ball speed is stabilized across the entire face, making it easier to predict the ball rolling distance during a mis-hit. 【0018】 The face insert has a plurality of regions or zones that form the striking face or a sub-striking face in order to provide a durometer hardness change profile to the putter. Each region of the plurality of regions has a hardness value different from that of an adjacent region. Specifically, the hardness of a region located at or near the center is lower than the hardness of a region away from the geometric center. The hardness profile can vary in the heel-to-toe direction, the vertical direction, or both. The number of regions forming the striking face or the sub-striking face can be any of 3 to 20, and by doing so, the hardness of the insert changes and the ball speed is stabilized across the entire face. Various embodiments of the face insert forming a durometer hardness change profile are described herein. 【0019】 (I. Overview of the Putter) An exemplary putter-type clubhead 100 with a face insert having a plurality of durometer hardnesses according to an aspect of the present invention is shown in FIGS. 1 and 2. The putter-type clubhead 100 includes a body 101, a toe end 102, a heel end 104 opposite the toe end 102, a front end portion 106, a rear end portion 108 opposite the front end portion 106, an upper portion 110, a lower portion 112 opposite the upper portion 110, and a front face 114. A leading edge 117 extends along at least a portion of the outer periphery of the front end portion 106, and an inner side wall 119 extends from the leading edge 117 to a sunken front wall 118 facing forward. The leading edge 117, the inner side wall 119, and the sunken front wall 118 together define a front recess 116 that extends from the front face 114 toward the rear end portion 108. As best shown in FIG. 3, the clubhead 100 further includes a face insert 120 disposed in the front recess 116 and having a geometric center 5 (hereinafter "GC"). 【0020】 The clubhead 100 of FIGS. 1 and 2 resembles a blade-type putter. In other embodiments, the clubhead 100 may be a mid-mallet-type putter or a mallet-type putter. The face insert having a plurality of durometer hardnesses described herein can be used in any desired style of putter and enables a stable roll speed. 【0021】 The putter-type clubhead has a loft angle of less than 10 degrees and has a flat or planar striking face. The putter-type clubhead has a generally rectangular front face, the height of the front face measured in the vertical direction is typically less than 1.25 inches, and the width of the front face measured in the heel-to-toe direction exceeds 3.25 inches. The upper and lower edges of the striking face may be substantially horizontal (i.e., parallel to the ground surface). 【0022】 The mass of the putter-type clubhead may be between 275 and 375 grams. In some embodiments, the mass of the putter-type clubhead may be between 275 and 300 grams, between 300 and 325 grams, between 325 and 350 grams, or between 350 and 375 grams. 【0023】 (II. Embodiment of the insert) An exemplary face insert 120 having a durometer hardness change profile according to an aspect of the present invention is shown in Figures 3 to 5. In this embodiment, the face insert 120 has a three-layer structure comprising a face plate 122, an intermediate layer 124, and an adhesive layer 126. The face plate 122 is the outer layer, and the adhesive layer 126 is the inner layer. The face plate 122 forms part of the front surface 114 of the club head 100 and is configured to collide with the golf ball during a putting stroke. The adhesive layer 126 is the innermost layer and is configured to connect the face insert 120 to the recessed front wall 118 of the body 101. The intermediate layer 124 is located between the adhesive layer 126 and the face plate 122. In other embodiments, the face insert 120 may have a single-layer structure in which the intermediate layer 124 is co-molded with the club head 100, or it may have a two-layer structure without a face plate 122, in which the intermediate layer 124 forms part of the outer surface and the front surface 114. 【0024】 The thickness of the faceplate 122 may be between 0.005 inches and 0.075 inches. In some embodiments, the thickness of the faceplate is between 0.005 and 0.010 inches, 0.010 and 0.020 inches, 0.020 and 0.030 inches, 0.030 and 0.040 inches, 0.040 and 0.050 inches, 0.050 and 0.060 inches, or 0.060 and 0.075 inches. In some embodiments, the thickness of the faceplate 122 may be less than 0.075 inches, less than 0.070 inches, less than 0.065 inches, less than 0.060 inches, less than 0.055 inches, less than 0.050 inches, or less than 0.045 inches. The thickness of the faceplate 122 may be adjusted so that the sound and feel of the putter are as desired. 【0025】 The intermediate layer 124 comprises multiple regions or zones having varying hardnesses so as to form a durometer hardness change profile. In the embodiments shown in Figures 3 to 5, the intermediate layer 124 comprises a central zone 130, a first toe zone 140, a first heel zone 145, a second toe zone 150, a second heel zone 155, a third toe zone 160, and a third heel zone 165. The first toe zone 140 is located between the central zone 130 and the toe end 102. The first heel zone 145 is located between the central zone 130 and the heel end 104. The second toe zone 150 is located between the first toe zone 140 and the toe end 102. The second heel zone 155 is located between the first heel zone 145 and the heel end 104. The third toe zone 160 is located between the second toe zone 150 and the toe end 102. The third heel zone 165 is located between the second heel zone 155 and the heel end 104. 【0026】 The central zone 130 comprises a central zone toe surface 132, a central zone heel surface 134, and a central zone midline 136 located midway (equally distanced) between the central zone heel surface 134 and the central zone toe surface 132. In some embodiments, the central zone midline 136 intersects the geometric center 5 or lies coplanar with the GC midline 10. In other embodiments, the central zone midline 136 may be offset to the toe end or heel end relative to the GC midline 10. The central zone 130 is formed of a central zone material having a central zone hardness of 10 to 35 on the Shore D hardness scale. The central zone 130 influences energy transfer to a center-hit ball. Therefore, by having the lowest durometer hardness among the multiple zones, the central zone 130 strategically blunts center impacts, thus equalizing the smash factor across the entire hitting face. The central zone 130 forms the portion of the intermediate layer that includes the geometric center 5. 【0027】 The first toe zone 140 comprises a first toe zone outer surface 141, a first toe zone inner surface 142, and a first toe zone midline 143 located midway (equally distanced) between the first toe zone inner surface 142 and the first toe zone outer surface 141. The first toe zone outer surface 141 is located on the toe side of the first toe zone midline 143. The first toe zone inner surface 142 is located on the heel side of the first toe zone midline 143. The first toe zone inner surface 142 is configured to abut against or be adjacent to the central zone toe surface 132. The first toe zone 140 is formed of a first toe zone material having a first toe zone hardness of 15 to 40 on the Shore D hardness scale. The hardness of the first toe zone (140) is greater than that of the center zone (130), but less than that of the second toe zone (150) and the third toe zone (160). The first toe zone (140) affects energy transfer to off-center hits that occur closer to the toe than the center zone (130) and closer to the heel than the second toe zone (150). 【0028】 The first heel zone 145 comprises a first heel zone outer surface 146, a first heel zone inner surface 147, and a first heel zone midline 148 located midway (equally distanced) between the first heel zone inner surface 147 and the first heel zone outer surface 146. The first heel zone outer surface 146 is located on the heel side of the first heel zone midline 148. The first heel zone inner surface 147 is located on the toe side of the first heel zone midline 148. The first heel zone inner surface 147 is in contact with the central zone heel surface 134. The first heel zone 145 is formed of a first heel zone material having a first heel zone hardness of 15 to 40 on the Shore D hardness scale. The hardness of the first heel zone 145 is greater than the hardness of the central zone 130, but less than the hardness of the second heel zone 155 and the third heel zone 165. 【0029】 The second toe zone 150 comprises a second toe zone outer surface 151, a second toe zone inner surface 152, and a second toe zone midline 153 located midway (equally distanced) between the second toe zone inner surface 152 and the second toe zone outer surface 151. The second toe zone outer surface 151 is located toe-side from the second toe zone midline 153. The second toe zone inner surface 152 is located heel-side from the second toe zone midline 153. The second toe zone inner surface 152 is in contact with the first toe zone outer surface 141. The second toe zone 150 is formed of a second toe zone material having a second toe zone hardness of 20 to 45 on the Shore D hardness scale. Since the hardness of the second toe zone is greater than that of the first toe zone, the ball roll distance and smash factor are uniform in these zones. The second toe zone 150 affects energy transfer during off-center hits in the area between the central zone 130 and the toe end 102. 【0030】 The second heel zone 155 comprises a second heel zone outer surface 156, a second heel zone inner surface 157, and a second heel zone midline 158 located midway (equally distanced) between the second heel zone inner surface 157 and the second heel zone outer surface 156. The second heel zone outer surface 156 is located on the heel side of the second heel zone midline 158. The second heel zone inner surface 157 is located on the toe side of the second heel zone midline 158. The second heel zone inner surface 157 is in contact with the first heel zone outer surface 146. The second heel zone 155 is formed of a second heel zone material having a second heel zone hardness of 20 to 45 on the Shore D hardness scale. Since the hardness of the second heel zone is greater than the hardness of the first heel zone and the central zone, the ball roll distance and smash factor are made uniform across the entire face. The second heel zone 155 affects energy transfer during off-center hits in the area between the first heel zone 145 and the heel end 104. 【0031】 The third toe zone 160 comprises a third toe zone outer surface 161, a third toe zone inner surface 162, and a third toe zone midline 163 located midway (equally distanced) between the third toe zone outer surface 161 and the third toe zone inner surface 162. The third toe zone outer surface 161 is located to the toe side of the third toe zone midline 163. The third toe zone inner surface 162 is located heel side of the third toe zone midline 163. The third toe zone inner surface 162 is in contact with the second toe zone outer surface 151. The third toe zone 160 is formed of a third toe zone material having a third toe zone hardness of 25 to 55 on the Shore D hardness scale. The hardness of the third toe zone is greater than that of the second toe zone, the first toe zone, and the center zone, resulting in a more uniform ball roll distance and smash factor across the entire face. The third toe zone 160 affects energy transfer during off-center hits in the area between the second toe zone 150 and the toe edge 102. 【0032】 The third heel zone 165 comprises a third heel zone outer surface 166, a third heel zone inner surface 167, and a third heel zone midline 168 located midway (equally distanced) between the third heel zone outer surface 166 and the third heel zone inner surface 167. The third heel zone outer surface 166 is located on the heel side of the third heel zone midline 168. The third heel zone inner surface 167 is located on the toe side of the third heel zone midline 168. The third heel zone inner surface 167 is in contact with the second heel zone outer surface 156. The third heel zone 165 is formed of a third heel zone material having a third heel zone hardness of 25 to 55 on the Shore D hardness scale. Since the third heel zone hardness is greater than the second heel zone hardness, the first heel zone hardness, and the central zone hardness, the ball roll distance and smash factor are uniform across the entire face. The third heel zone 165 affects energy transfer during off-center hits in the area between the second heel zone 155 and the heel end 104. 【0033】 The position of each zone relative to the GC midface 10 may be selected so that the putter is given a desired durometer hardness change profile. In some embodiments, the central zone midline 136 may coincide with the GC midface 10. In other embodiments, the central zone midline 136 may be offset towards the heel or toe by a distance of 0.01 to 0.25 inches. For example, in some embodiments, the central zone midline 136 may be offset from the GC midface 10 by a distance of 0.01 to 0.075 inches, 0.075 to 0.10 inches, 0.10 to 0.15 inches, 0.15 to 0.20 inches, or 0.20 to 0.25 inches. The offset distance of the central zone midline 136 may be adjusted so that the central zone material is positioned at any desired location. The offset distance of the central zone midline 136 may be adjusted by changing the position of the central zone toe face 132 and the central zone heel face 134 relative to the GC midface 10. 【0034】 Similarly, the central zone hardness may be selected to strategically blunt the center impact while obtaining a desired smash factor in the central zone. As described above, the central zone hardness may be 10–35 on the Shore D hardness scale. For example, in some embodiments, the central zone hardness may be 10–15, 15–20, 20–25, 25–30, or 30–35 on the Shore D hardness scale. In some embodiments, the central zone hardness may be less than 35, less than 30, less than 25, less than 20, or less than 15 on the Shore D hardness scale. The central zone hardness is lower than the first toe zone hardness and the first heel zone hardness. 【0035】 In some embodiments, the first toe zone centerline 143 may be located at a distance of 0.10 to 0.50 inches from the GC center plane 10 toward the toe. For example, in some embodiments, the first toe zone centerline 143 may be located at a distance of 0.10 to 0.20 inches, 0.20 to 0.30 inches, 0.30 to 0.40 inches, or 0.40 to 0.50 inches from the GC center plane 10. In some embodiments, the first toe zone centerline 143 may be located at a distance of less than 0.50 inches, less than 0.45 inches, less than 0.40 inches, less than 0.35 inches, less than 0.30 inches, less than 0.25 inches, less than 0.20 inches, or less than 0.15 inches from the GC center plane 10. The position and distance of the first toe zone midline 143 relative to the GC midface 10 may be adjusted so as to obtain a desired durometer hardness profile, that is, so as to obtain a desired smash factor in the first toe zone 140. 【0036】 Similarly, the first toe zone hardness may be selected such that a desired smash factor is obtained in the first toe zone 140. As described above, the first toe zone hardness may be 15 to 40 on the Shore D hardness scale. For example, in some embodiments, the first toe zone hardness may be 15 to 20, 20 to 25, 25 to 30, 30 to 35, or 35 to 40 on the Shore D hardness scale. In some embodiments, the first toe zone hardness may 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 on the Shore D hardness scale. The first toe zone hardness is greater than the mid-zone hardness. The hardness of the first toe zone may be adjusted according to the size and position of the first toe zone 140. 【0037】 In some embodiments, the first heel zone midline 148 may be located at a distance of 0.10 to 0.50 inches from the GC midface 10 toward the heel. For example, in some embodiments, the first heel zone midline 148 may be located at a distance of 0.10 to 0.20 inches, 0.20 to 0.30 inches, 0.30 to 0.40 inches, or 0.40 to 0.50 inches from the GC midface 10. In some embodiments, the first heel zone midline 148 may be located at a distance of less than 0.50 inches, less than 0.45 inches, less than 0.40 inches, less than 0.35 inches, less than 0.30 inches, less than 0.25 inches, less than 0.20 inches, or less than 0.15 inches from the GC midface 10. The position and offset distance of the first heel zone midline 148 relative to the CG midface 10 may be adjusted by changing the arrangement of the first heel zone outer surface 146 and the first heel zone inner surface 147. These positions and offset distances may be adjusted to obtain a desired smash factor in the first heel zone 145 and to ensure that the smash factor is uniform across the entire striking surface. 【0038】 Similarly, the first heel zone hardness may be selected such that a desired smash factor is obtained in the first heel zone 145. As described above, the first heel zone hardness may be 15 to 40 on the Shore D hardness scale. For example, in some embodiments, the first heel zone hardness may be 15 to 20, 20 to 25, 25 to 30, 30 to 35, or 35 to 40 on the Shore D hardness scale. In some embodiments, the first heel zone hardness may 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 on the Shore D hardness scale. The first heel zone hardness is greater than the mid-zone hardness. In some embodiments, the first heel zone hardness is equal to the first toe zone hardness. In other embodiments, the hardness of the first heel zone is less than the hardness of the first toe zone. In other embodiments, the hardness of the first heel zone is greater than the hardness of the first toe zone. For example, in one embodiment, the hardness of the first heel zone may be 31 on the Shore D hardness scale, and the hardness of the first toe zone may be 37 on the Shore D hardness scale. The hardness of the first heel zone may be adjusted according to the size and position of the first heel zone 145. 【0039】 The second toe zone centerline 153 may be located at a distance of 0.15 to 0.75 inches from the GC center plane 10 toward the toe. For example, in some embodiments, the second toe zone centerline 153 may be located at a distance of 0.15 to 0.20 inches, 0.20 to 0.30 inches, 0.30 to 0.40 inches, 0.40 to 0.50 inches, 0.50 to 0.60 inches, or 0.60 to 0.75 inches from the GC center plane 10. In some embodiments, the second toe zone centerline 153 may be located at a distance of less than 0.50 inches, less than 0.45 inches, less than 0.40 inches, less than 0.35 inches, less than 0.30 inches, less than 0.25 inches, less than 0.20 inches, or less than 0.15 inches from the GC center plane 10. The position and offset distance of the second toe zone center line 153 relative to the GC center surface 10 may be adjusted by changing the arrangement of the second toe zone outer surface 151 and the second toe zone inner surface 152. These positions and offset distances may be adjusted to obtain a desired smash factor in the second toe zone 150 and to ensure that the smash factor is uniform across the entire striking surface. 【0040】 Similarly, the hardness of the second toe zone may be adjusted so that a desired smash factor is obtained in the second toe zone 150. As described above, the hardness of the second toe zone may be 20 to 45 on the Shore D hardness scale. For example, in some embodiments, the hardness of the second toe zone may be 20 to 25, 25 to 30, 30 to 35, 35 to 40, or 40 to 45 on the Shore D hardness scale. In some embodiments, the hardness of the second toe zone may be 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, or 45. The hardness of the second toe zone is greater than the hardness of the central zone and the hardness of the first toe zone. The hardness of the second toe zone may be adjusted according to the size and position of the second toe zone 150. 【0041】 The second heel zone midline 158 may be located at a distance of 0.15 to 0.75 inches from the GC midplane 10 toward the heel. For example, in some embodiments, the second heel zone midline 158 may be located at a distance of 0.15 to 0.20 inches, 0.20 to 0.30 inches, 0.30 to 0.40 inches, 0.40 to 0.50 inches, 0.50 to 0.60 inches, or 0.60 to 0.75 inches from the GC midplane 10. In some embodiments, the second heel zone midline 158 may be located at a distance of less than 0.50 inches, less than 0.45 inches, less than 0.40 inches, less than 0.35 inches, less than 0.30 inches, less than 0.25 inches, less than 0.20 inches, or less than 0.15 inches from the GC midplane 10. The position and offset distance of the second heel zone center line 158 relative to the GC center surface 10 may be adjusted by changing the arrangement of the second heel zone outer surface 156 and the second heel zone inner surface 157. These positions and offset distances may be adjusted to obtain a desired smash factor in the second heel zone 155 and to ensure that the smash factor is uniform across the entire striking surface. 【0042】 Similarly, the hardness of the second heel zone may be selected such that a desired smash factor is obtained in the second heel zone 155. As described above, the hardness of the second heel zone may be 20 to 45 on the Shore D hardness scale. For example, in some embodiments, the hardness of the second heel zone may be 20 to 25, 25 to 30, 30 to 35, 35 to 40, or 40 to 45 on the Shore D hardness scale. In some embodiments, the hardness of the second heel zone may be 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, or 45 on the Shore D hardness scale. The hardness of the second heel zone is greater than the hardness of the central zone and the hardness of the first heel zone. In some embodiments, the hardness of the second heel zone is equal to the hardness of the second toe zone. In other embodiments, the hardness of the second heel zone is less than the hardness of the second toe zone. In other embodiments, the hardness of the second heel zone is greater than the hardness of the second toe zone. For example, in one embodiment, the hardness of the second heel zone may be 38 on the Shore D hardness scale, and the hardness of the second toe zone may be 41 on the Shore D hardness scale. The hardness of the second heel zone may be adjusted as appropriate depending on the size and position of the second heel zone 155. 【0043】 The third toe zone centerline 163 is located at a distance of 0.20 to 1.5 inches from the GC center face 10 toward the toe. For example, the third toe zone centerline 163 may be located at a distance of 0.20 to 0.30 inches, 0.30 to 0.40 inches, 0.40 to 0.50 inches, 0.50 to 0.60 inches, 0.60 to 0.70 inches, 0.70 to 0.80 inches, 0.80 to 0.90 inches, 0.90 to 1.00 inches, 1.0 to 1.1 inches, 1.1 to 1.2 inches, 1.2 to 1.3 inches, 1.3 to 1.4 inches, or 1.4 to 1.5 inches from the GC center face 10. In some embodiments, the third toe zone centerline 163 may be located at a distance of less than 1.5 inches, less than 1.4 inches, less than 1.3 inches, less than 1.2 inches, less than 1.1 inches, less than 1.0 inch, less than 0.9 inches, or less than 0.8 inches from the GC center surface 10. The position and offset distance of the third toe zone centerline 163 relative to the GC center surface 10 may be adjusted by changing the arrangement of the third toe zone outer surface 161 and the third toe zone inner surface 162. These positions and offset distances may be adjusted to obtain a desired smash factor in the third toe zone 160 and to ensure that the smash factor is uniform across the entire striking surface. 【0044】 Similarly, the third toe zone hardness may be selected such that a desired smash factor is obtained in the third toe zone 160. As described above, the third toe zone hardness may be 25 to 50 on the Shore D hardness scale. For example, in some embodiments, the third toe zone hardness may be 20 to 25, 25 to 30, 30 to 35, 35 to 40, or 40 to 45 on the Shore D hardness scale. In some embodiments, the third toe zone hardness may be 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, or 45 on the Shore D hardness scale. The third toe zone hardness is greater than the central zone hardness, the first toe zone hardness, and the second toe zone hardness. The hardness of the third toe zone may be adjusted according to the size and position of the third toe zone 160. 【0045】 The third heel zone midline 168 may be located at a distance of 0.20 to 1.5 inches from the GC midplane 10 toward the heel. For example, in some embodiments, the third heel zone midline 168 may be located at a distance of 0.20 to 0.30 inches, 0.30 to 0.40 inches, 0.40 to 0.50 inches, 0.50 to 0.60 inches, 0.60 to 0.70 inches, 0.70 to 0.80 inches, 0.80 to 0.90 inches, 0.90 to 1.00 inches, 1.0 to 1.1 inches, 1.1 to 1.2 inches, 1.2 to 1.3 inches, 1.3 to 1.4 inches, or 1.4 to 1.5 inches from the GC midplane 10. In some embodiments, the third heel zone centerline 168 may be located at a distance of less than 1.5 inches, less than 1.4 inches, less than 1.3 inches, less than 1.2 inches, less than 1.1 inches, less than 1.0 inches, less than 0.9 inches, or less than 0.8 inches from the GC center surface 10. The position and offset distance of the third heel zone centerline 168 relative to the GC center surface 10 may be adjusted by changing the arrangement of the third heel zone outer surface 166 and the third heel zone inner surface 167. These positions and offset distances may be adjusted to obtain a desired smash factor in the third heel zone 165 and to equalize the smash factor across the entire striking surface. 【0046】 The median lines 143, 148, 153, 158, 163, and 168 may be symmetrical or asymmetrical with respect to the GC median 10. In some embodiments, the first toe zone median 143 and the first heel zone median 148 are equidistant from the GC median 10, the second toe zone median 153 and the second heel zone median 158 are equidistant from the GC median 10, and / or the third toe zone median 163 and the third heel zone median 168 are equidistant from the GC median 10. In other embodiments, the first toe zone median 143 and the first heel zone median 148 are at different distances from the GC median 10, the second toe zone median 153 and the second heel zone median 158 are at different distances from the GC median 10, and / or the third toe zone median 163 and the third heel zone median 168 are at different distances from the GC median 10. 【0047】 The thickness of the intermediate layer 124 may be between 0.025 inches and 0.75 inches. For example, the thickness of the intermediate layer 124 may be between 0.025 and 0.10 inches, 0.10 and 0.20 inches, 0.20 and 0.30 inches, 0.30 and 0.40 inches, 0.40 and 0.50 inches, 0.50 and 0.60 inches, or 0.60 and 0.75 inches. In some embodiments, the thickness of the intermediate layer 124 may be less than 0.75 inches, less than 0.70 inches, less than 0.65 inches, less than 0.60 inches, less than 0.55 inches, or less than 0.50 inches. In other embodiments, the thickness of the intermediate layer 124 may be greater than 0.025 inches, greater than 0.050 inches, greater than 0.075 inches, greater than 0.10 inches, greater than 0.15 inches, greater than 0.20 inches, or greater than 0.25 inches. 【0048】 The size, shape, number, and position of the zones may be modified according to the embodiments of the invention so that the smash factor and ball speed at a desired position on the face are adjusted by a desired durometer hardness profile. For example, lowering the durometer hardness of a zone lowers the smash factor, and raising the durometer hardness of a zone raises the smash factor. Similarly, positioning the zones near the GC midface 10 raises the smash factor, and positioning the zones farther from the GC midface 10 lowers the smash factor. The number of zones may be increased or decreased depending on the desired smash factor profile at a particular position on the face. The zones may be positioned so that the smash factor profile is adjusted in the heel-toe direction and / or vertical direction. Figures 6 to 13 show various exemplary embodiments of putter face inserts with a durometer hardness variation profile. 【0049】 Figure 6 shows another exemplary putter-type club head 200 having a durometer hardness change profile shifted towards the toe. The club head 200 comprises a toe end 202, a heel end 204, and a face insert 220 that forms part of the front surface 214. The face insert 220 of this embodiment is similar to the face insert 120 described above in that it has a durometer hardness change profile having a central zone 230, a first toe zone 240, a first heel zone 245, a second toe zone 250, a second heel zone 255, a third toe zone 260, and a third heel zone 265. The face insert 220 differs from the face insert 120 in that the central zone midline 236 of the central zone 230 is offset towards the toe from the GC middle surface 10. In other words, the central zone midline 236 does not coincide with the GC middle surface 10. Similarly, the first toe zone midline 243, the first heel zone midline 248, the second toe zone midline 253, the second heel zone midline 258, the third toe zone midline 263, and the third heel zone midline 268 are also offset toward the toe from the GC midface 10, resulting in an asymmetric durometer hardness profile with respect to the GC midface 10. The first toe zone midline 243, the second toe zone midline 253, and the third toe zone midline 263 are located further from the GC midface 10 than the first heel zone midline 248, the second heel zone midline 258, and the third heel zone midline 268, respectively. 【0050】 Figure 7 shows another exemplary putter-type club head 300 having a durometer hardness variation profile with zones of different widths. The club head 300 comprises a toe end 302, a heel end 304, and a face insert 320 that forms part of the front surface 314. The face insert 320 is similar to the face inserts 120 and 220 described above in that it comprises multiple zones that form the durometer hardness variation profile. The face insert 320 differs from the face inserts 120 and 220 described above in that the face 320 comprises zones of different shapes, has no central zone, and includes two additional zones at both the heel end 304 and the toe end 302. In this embodiment, the GC middle surface 10 is located at the junction of the first toe zone 340 and the first heel zone 345, and there is no central zone. In this embodiment, with the exception of the fifth toe zone 380 and the fifth heel zone 385, the outer zones have a smaller width than the adjacent inner zones. Therefore, the width of the fourth toe zone 370 and the width of the fourth heel zone 375 are smaller than the width of the third toe zone 360 ​​and the width of the third heel zone 365, respectively. Furthermore, the width of the third toe zone 360 ​​and the width of the third heel zone 365 are smaller than the width of the second toe zone 350 and the width of the second heel zone 355, respectively. The width of the second toe zone 350 and the width of the second heel zone 355 are smaller than the width of the first toe zone 340 and the width of the first heel zone 345, respectively. 【0051】 Figure 8 shows another exemplary putter-type club head 400 having a durometer hardness change profile with a large central zone and a small peripheral zone. The club head 400 comprises a toe end 402, a heel end 404, and a face insert 420 that forms part of the front 414. The face insert 420 is similar to the face inserts 120, 220, and 320 described above in that it comprises multiple zones that form the durometer hardness change profile. The face insert 420 differs from the face inserts 120, 220, and 320 described above in that it has zones of different sizes. Specifically, the face insert 420 comprises four or five outer zones, each of which has the same minimum width. The face insert 420 comprises a third toe zone 460, a fourth toe zone 470, a fifth toe zone 480, and a sixth toe zone 490, all of which have the same width. The widths of zones 460, 470, 480, and 490 are smaller than the widths of the second toe zone 450 and the first toe zone 440. Similarly, the third heel zone 465, the fourth heel zone 475, the fifth heel zone 485, and the sixth heel zone 495 all have the same width. The widths of zones 465, 475, 485, and 495 are smaller than the widths of the second heel zone 455 and the first heel zone 445. 【0052】 Figure 9 shows another exemplary putter-type club head 500 having a durometer hardness variation profile with a chevron pattern. The club head 500 comprises a toe end 502, a heel end 504, and a face insert 520 that forms part of the front surface 514. The face insert 520 is similar to the face inserts 120, 220, 320, and 420 described above in that it has multiple zones that form the durometer hardness variation profile. The face insert 520 differs from the face inserts 120, 220, 320, and 420 described above in that it has zones of different shapes. Specifically, the face insert 520 has multiple V-shaped zones or sloping zones, rather than vertical columnar zones. The face insert 520 comprises a central zone 530, a first toe zone 540, a first heel zone 545, a second toe zone 550, a second heel zone 555, a third toe zone 560, and a third heel zone 565. The central zone has a diamond shape, and the width of the central zone decreases towards the top and bottom of the face. The first toe zone 540, the second toe zone 550, and the third toe zone 560 are V-shaped, with the upper and lower ends of each zone inclined toward the GC middle surface 10. Similarly, the first heel zone 545, the second heel zone 555, and the third heel zone 565 are also V-shaped, with the upper and lower ends of each zone inclined toward the GC middle surface 10. The V-shape of the zones creates a durometer hardness change profile in both the vertical and heel-toe directions. 【0053】 Figure 10 shows another exemplary putter-type club head 600 having a durometer hardness change profile with arc-shaped zones. The club head 600 comprises a toe end 602, a heel end 604, and a face insert 620 that forms part of the front 614. The face insert 620 is similar to the face inserts 120, 220, 320, 420, and 520 described above in that it has multiple zones that form a durometer hardness change profile. The face insert 620 differs from the face inserts 120, 220, 320, 420, and 520 described above in that it has zones of different shapes. Instead of the V-shaped zones seen in face insert 520, the face insert 620 has curved or arc-shaped zones. 【0054】 Figure 11 shows another exemplary putter-type club head 700 having a durometer hardness change profile with zones of less slope. The club head 700 comprises a toe end 702, a heel end 704, and a face insert 720 that forms part of the front 714. The face insert 720 is similar to the face inserts 120, 220, 320, 420, 520, and 620 described above in that it has multiple zones that form the durometer hardness change profile. The face insert 720 differs from the face inserts 120, 220, 320, 420, 520, and 620 described above in that it has zones of different shapes. Instead of the vertical columnar zones seen in the face inserts 120, 220, 320, and 420, the face insert 720 has sloped zones. Specifically, the upper part of the zone is located closer to the toe than the lower part of the zone. 【0055】 Figure 12 shows another exemplary putter-type club head 800 having a durometer hardness change profile with zones of greater inclination. The club head 800 comprises a toe end 802, a heel end 804, and a face insert 820 that forms part of the front surface 814. The face insert 820 is similar to the face insert 720 described above in that it has multiple inclined zones that form a durometer hardness change profile. The face insert 820 differs from the face insert 720 in that the inclination angles of the zones of the face insert 820 are greater. 【0056】 Figure 13 shows another exemplary putter-type club head 900 having a durometer hardness variation profile with horizontal zones. The club head 900 comprises a toe end 902, a heel end 904, and a face insert 920 that forms part of the front 914. The face insert 920 is similar to the face inserts 120, 220, 320, 420, 520, and 620 described above in that it has multiple zones that form the durometer hardness variation profile. The face insert 920 differs from the face inserts 120, 220, 320, 420, 520, and 620 in that it has zones of different shapes. Instead of the vertical columnar zones found in the face inserts 120, 220, 320, and 420, the face insert 920 has inclined zones. Specifically, the upper part of the zone is located closer to the toe than the lower part of the zone. 【0057】 In some embodiments, transition zones are provided between zones having a constant durometer hardness, where the durometer hardness gradually changes, so that the overall durometer hardness profile of the face insert does not change abruptly but gradually. For example, the transition zone may consist of two or more microzones, and since the difference in durometer hardness between these microzones is relatively small, the hardness changes gradually between the two durometer hardness regions. In one embodiment, a transition zone located between a zone with a Shore D hardness of 30 and another zone with a Shore D hardness of 35 may consist of four microzones with hardnesses of 31, 32, 33, and 34 on the Shore D hardness scale, thereby making the change between the zone with a Shore D hardness of 30 and the zone with a Shore D hardness of 35 more gradual. 【0058】 (III. Materials) The faceplate 122 may be formed from any of the following materials: aluminum, stainless steel, copper, thermoplastic copolyester elastomer (TPC), thermoplastic elastomer (TPE), thermoplastic urethane (TPU), steel, nickel, TPU / aluminum, TPE / aluminum, plastic / metal screen insert, polyethylene, polypropylene, polytetrafluoroethylene, polyisobutylene, polyvinyl chloride, PEBAX®, and any other desired material. The outer layer material may be selected to obtain desired sound and / or feel characteristics. The faceplate may further have grooves to improve grip and spin, if necessary. The faceplate is configured to cover an intermediate layer having varying durometer hardnesses, resulting in a uniform striking surface made of a single material. 【0059】 The intermediate layer may be formed of PEBAX® material. PEBAX® is a polyether block amide, a thermoplastic elastomer composed of a flexible polyether and a rigid polyamide. The rigid polyamide may include nylon. PEBAX® may contain various compounds corresponding to different Shore D hardness values, polyether proportions, and / or polyamide proportions. The smash factor profile may be adjusted by varying the hardness by changing the chemical composition of PEBAX® between zones of the intermediate layer. 【0060】 In many embodiments, PEBAX® in different zones may include PEBAX® 4033 (Arkema, Paris, France) or PEBAX® 6333 (Arkema, Paris, France). PEBAX® 4033 (Arkema, Paris, France) contains tetramethylene oxide (53 wt%) and nylon 12. PEBAX® 6333 (Arkema, Paris, France) contains nylon 11. 【0061】 PEBAX® may contain a proportion of polyether by volume. In some embodiments, PEBAX® may contain 0% to 10%, 10% to 20%, 15% to 30%, 20% to 30%, 30% to 40%, 30% to 50%, 30% to 60%, 40% to 50%, 40% to 60%, 50% to 60%, or 60% to 70% by volume. For example, PEBAX® may contain 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70% by volume. In some embodiments, PEBAX® may contain 0% to 10%, 10% to 20%, 15% to 30%, 20% to 30%, 30% to 40%, 40% to 50%, 40% to 60%, 50% to 60%, or 60% to 70% by volume. For example, PEBAX® may contain 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70% by volume. The higher the proportion of polyether, the lower the hardness of PEBAX®. The higher the proportion of polyamide, the higher the hardness of PEBAX®. For example, PEBAX® 4033 (Arkema, Paris, France) may contain 40% to 60% polyether and 15% to 30% polyamide by volume. For example, PEBAX® 6333 (Arkema, Paris, France) may contain 15% to 30% polyether and 40% to 60% polyamide by volume. 【0062】 In many embodiments, the hardness of PEBAX® may be Shore 15D to Shore 75D. In some embodiments, the hardness of PEBAX® may be Shore 15D to Shore 25D, Shore 25D to Shore 35D, Shore 35D to Shore 45D, Shore 36D to Shore 44D, Shore 38D to Shore 42D, Shore 45D to Shore 55D, Shore 55D to Shore 65D, Shore 56D to Shore 64D, Shore 60D to Shore 65D, or Shore 65D to Shore 75D. For example, the hardness of PEBAX® may be Shore D 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70. 【0063】 In many embodiments, the hardness of PEBAX® 4033 (Arkema, Paris, France) may be lower than that of PEBAX® 6333 (Arkema, Paris, France). In many embodiments, the hardness of PEBAX® 4033 (Arkema, Paris, France) may be Shore 15D to Shore 55D. In some embodiments, the hardness of PEBAX® 4033 (Arkema, Paris, France) may be Shore 38D to Shore 42D, or Shore 39D to Shore 41D. For example, the hardness of PEBAX® 4033 (Arkema, Paris, France) may be Shore D 40. In many embodiments, the hardness of PEBAX® 6333 (Arkema, Paris, France) may be Shore 50D to Shore 75D. In some embodiments, the hardness of PEBAX® 6333 (Arkema, Paris, France) may be Shore 55D to Shore 70D, or Shore 60D to Shore 65D. For example, the hardness of PEBAX® 6333 (Arkema, Paris, France) may be 63 on the Shore D scale. 【0064】 In many embodiments, the hardness of PEBAX® 4033 (Arkema, Paris, France) may be lower than that of PEBAX® 6333 (Arkema, Paris, France). In many embodiments, the hardness of PEBAX® 4033 (Arkema, Paris, France) may be Shore 35D to Shore 55D. In some embodiments, the hardness of PEBAX® 4033 (Arkema, Paris, France) may be Shore 38D to Shore 42D, or Shore 39D to Shore 41D. For example, the hardness of PEBAX® 4033 (Arkema, Paris, France) may be Shore D 40. In many embodiments, the hardness of PEBAX® 6333 (Arkema, Paris, France) may be Shore 50D to Shore 75D. In some embodiments, the hardness of PEBAX® 6333 (Arkema, Paris, France) may be Shore 55D to Shore 70D, or Shore 60D to Shore 65D. For example, the hardness of PEBAX® 6333 (Arkema, Paris, France) may be 63 on the Shore D scale. 【0065】 In other embodiments, the intermediate layer having various durometer hardnesses is made of thermoplastic copolyester elastomer (TPC), thermoplastic elastomer (TPE), thermoplastic urethane (TPU), steel, nickel, TPU / aluminum, TPE / aluminum, plastic / metal screen insert, polyethylene, polypropylene, polytetrafluoroethylene, polyisobutylene, polyvinyl chloride, polycarbonate (PC), polyester (PBT), polyphenylene sulfide (PPS), polyamide (PA) (e.g., polyamide 6 (PA6), polyamide 6-6 (PA66), polyamide-12 (PA12), polyamide-612 (PA612), polyamide-11 (PA11)), thermoplastic polyurethane (TPU), polyphthalamide (PPA), acrylonitrile butadiene styrene (ABS), polybutylene terephthalate (PBT), polyvinylidene chloride (PVDF), polyethylene (PE), polyphenylene ether / oxide (PPE), polyoxymethyl It may be formed from any combination of ethylene (POM), polypropylene (PP), styrene acrylonitrile (SAN), polymethylpentene (PMP), polyethylene terephthalate (PET), acrylonitrile styrene acrylate (ASA), polyetherimide (PEI), polyvinylidene chloride (PVDF), polymethyl methacrylate (PMMA), polyetheretherketone (PEEK), polyetherketone (PEK), polyetherimide (PEI), polyethersulfone (PES), polyphenylene oxide (PPO), polystyrene (PS), polysulfone (PSU), polyvinyl chloride (PVC), liquid crystal polymer (LCP), thermoplastic elastomer (TPE), ultra-high molecular weight polyethylene (UHMWPE), and alloys of the above thermoplastic materials (e.g., alloys of acrylonitrile butadiene styrene (ABS) and polycarbonate (PC), alloys of acrylonitrile butadiene styrene (ABS) and polyamide (PA), etc.). 【0066】 (IV. Structure) In some embodiments, an intermediate layer is formed by joining together zones that have been formed individually. For example, a zone with a desired shape may be cut from a larger material having a desired durometer hardness. Another zone may be cut from another material having a different durometer hardness. At least a portion of the intermediate layer may then be formed by joining these two zones together. For example, the central zone toe face of the central zone may be connected to the inner surface of the first toe zone by adhesive or epoxy. More zones may be formed separately and attached as desired. In other embodiments, multiple zones may be formed integrally by a co-forming process or a multi-material injection molding process that forms two or more materials into a single part. Similarly, the faceplate may be formed separately and then attached, or it may be co-formed with the intermediate layer. 【0067】 The intermediate layer is secured to the club head body via an adhesive layer. The adhesive layer may be VHB tape, epoxy, or other similar adhesive material that securely fastens the intermediate layer to the body. In other embodiments, the intermediate layer may be attached to the club head body by co-molding, mechanical fasteners, press-fitting, or other fastening means. 【0068】 The face insert described herein achieves a consistent smash factor across the entire face by forming a central region or zone with the lowest durometer hardness material and increasing the durometer hardness of each outer zone in the heel-toe direction. By increasing the durometer hardness of the outer zones, energy loss to spin is offset, and a smash factor equivalent to that of a ball struck in the central zone can be obtained. The durometer hardness of the outer regions may be adjusted according to the distance from the geometric center so that the durometer hardness is increased. Thus, each zone of the face insert results in a change of less than 1.25% in the overall smash factor of the face, making the ball roll distance more predictable. 【0069】 (Section 1) A putter-type club head comprising: a body having a toe end, a heel end opposite to the toe end, a front end, a rear end opposite to the front end, an upper part, and a lower part opposite to the upper part; a front surface of the front end, and a front recess extending from the front surface toward the rear end; and a face insert positioned in the front recess and having a geometric center, wherein the face insert comprises a face plate, an intermediate layer, and an adhesive layer, and the intermediate layer comprises a central zone formed of a central zone material having a central zone hardness of 28 to 32 on the Shore D hardness scale, a first toe zone located between the central zone and the toe end and formed of a first toe zone material having a first toe zone hardness of 33 to 37 on the Shore D hardness scale, and a first heel zone located between the central zone and the heel end and formed of a first heel zone material having a first heel zone hardness of 30 to 35 on the Shore D hardness scale. 【0070】 (Section 2) A putter-type club head according to item 1, comprising a second toe zone located between the first toe zone and the toe end, a second heel zone located between the first heel zone and the heel end, wherein the first toe zone is adjacent to the central zone, and the first heel zone is adjacent to the central zone. 【0071】 (Section 3) The putter-type club head according to item 2, wherein the second toe zone is formed of a second toe zone material having a second toe zone hardness of 35 to 42 on the Shore D hardness scale, and the second heel zone is formed of a second heel zone material having a second heel zone hardness of 35 to 42 on the Shore D hardness scale. 【0072】 (Section 4) The putter-type club head according to item 3, wherein the intermediate layer is formed of PEBAX® material and the face plate is formed of aluminum material. 【0073】 (Section 5) The putter-type club head according to item 3, wherein the face plate has a thickness of less than 0.050 inches, and the intermediate layer has a thickness of 0.10 to 0.25 inches. 【0074】 (Section 6) A putter-type club head comprising a body having a toe end, a heel end opposite to the toe end, a front end, a rear end opposite to the front end, an upper part, and a lower part opposite to the upper part, and a face insert having a front surface, a front recess located on the front surface, and a geometric center, wherein the face insert comprises a face plate, an intermediate layer, and an adhesive layer, the face plate being made of a metal material, and any of the intermediate layer and the adhesive layer when the intermediate layer and the adhesive layer are located within the front recess The intermediate layer and the adhesive layer are completely covered so that no part is visible, and the faceplate forms a continuous front surface which is configured to form part of the front surface and collide with the golf ball, the intermediate layer comprises a central zone, a first toe zone, a first heel zone, a second toe zone, and a second heel zone, the central zone comprises a central zone toe surface and a central zone heel surface, the first toe zone comprises a first toe zone outer surface and a first toe zone inner surface, and the first heel zone comprises a first heel zone The toe zone comprises an outer surface and an inner surface of the first heel zone, the second toe zone comprises an outer surface and an inner surface of the second toe zone, the second heel zone comprises an outer surface and an inner surface of the second heel zone, the central zone toe surface abuts against the inner surface of the first toe zone, the central zone heel surface abuts against the inner surface of the first heel zone, the outer surface of the first heel zone abuts against the inner surface of the second heel zone, the outer surface of the first toe zone abuts against the inner surface of the second toe zone, and the central zone A putter-type club head having a central durometer hardness of 28-32 on the Shore D hardness scale, a first toe zone having a first toe zone durometer hardness of 33-37 on the Shore D hardness scale, a first heel zone having a first heel zone durometer hardness of 30-35 on the Shore D hardness scale, a second toe zone having a second toe zone durometer hardness of 35-42 on the Shore D hardness scale, and a second heel zone having a second heel zone durometer hardness of 35-42 on the Shore D hardness scale. 【0075】 (Section 7) The putter-type club head according to item 6, wherein the intermediate layer comprises a third heel zone and a third toe zone, the third heel zone comprises an outer surface of the third heel zone and an inner surface of the third heel zone, the third toe zone comprises an outer surface of the third toe zone and an inner surface of the third toe zone, the inner surface of the third heel zone abuts against the outer surface of the second heel zone, the inner surface of the third toe zone abuts against the outer surface of the second toe zone, the third heel zone has a third heel zone durometer hardness of 38 to 47 on the Shore D hardness scale, and the third toe zone has a third toe zone durometer hardness of 38 to 47 on the Shore D hardness scale. 【0076】 (Section 8) The body has a virtual insert midplane perpendicular to the ground plane and passing through the geometric center, the central zone has a central zone midline perpendicular to the front and equidistant from the inner surface of the first toe zone and the inner surface of the first heel zone and extending perpendicular to the front, the first heel zone has a first heel zone midline perpendicular to the front and equidistant from the outer surface of the first heel zone and the inner surface of the first heel zone, the second toe zone has a second toe midline perpendicular to the front and equidistant from the outer surface of the second toe zone and the inner surface of the second toe zone, the second heel zone has a second heel zone midline perpendicular to the front and equidistant from the outer surface of the second heel zone and the inner surface of the second heel zone, the third toe zone has a third toe zone midline perpendicular to the front and equidistant from the outer surface of the third toe zone and the inner surface of the third toe zone, and the third heel zone has a third heel The third heel zone has a third heel zone midline equidistant from the outer surface of the zone and the inner surface of the third heel zone, the third toe zone has a third toe zone midline perpendicular to the front surface and equidistant from the outer surface of the third toe zone and the inner surface of the third toe zone, the central zone midline is coplane with the middle surface of the virtual insert, the first heel zone midline is 0.20 to 0.30 inches away from the middle surface of the virtual insert, and the second toe zone midline is 0 inches away from the middle surface of the virtual insert The putter-type club head according to item 7, wherein the second heel zone midline is 0.45 to 0.55 inches away from the virtual insert midplane, the third toe zone midline is 0.45 to 0.55 inches away from the virtual insert midplane, the third heel zone midline is 0.65 to 0.75 inches away from the virtual insert midplane, and the third toe zone midline is 0.65 to 0.75 inches away from the virtual insert midplane. 【0077】 (Section 9) The putter-type club head according to item 7, wherein the face plate has a thickness of 0.005 to 0.050 inches, and the intermediate layer has a thickness of 0.025 to 0.25 inches. 【0078】 (Section 10) The putter-type club head according to item 9, wherein the front surface forms a loft angle of 0 to 8 degrees, the body has a weight of 345 to 380 grams, and the front surface has a maximum height of less than 1.25 inches. 【0079】 (Section 11) The putter-type club head according to item 8, wherein the face plate comprises a plurality of horizontal grooves extending in the heel-toe direction. 【0080】 (Section 12) A putter-type club head comprising: a body having a toe end, a heel end opposite to the toe end, a front end, a rear end opposite to the front end, an upper part, and a lower part opposite to the upper part; a face insert having a front surface, a front recess located on the front surface, and a geometric center; and a middle surface perpendicular to the ground plane and passing through the geometric center, wherein the face insert comprises a face plate, an intermediate layer, and an adhesive layer, wherein the face plate is located on the outside, the adhesive layer is located on the inside, and the intermediate layer is located between the face plate and the adhesive layer; and the face insert further comprises a first heel point, a first toe point, a first heel zone point, and a second toe point, wherein the first heel point is located 0.25 inches horizontally towards the heel from the middle surface, and the first toe A putter-type club head, wherein the first heel zone point is located 0.25 inches horizontally towards the toe from the middle surface, the second toe point is located 0.50 inches horizontally towards the heel from the middle surface, the intermediate layer has a central durometer hardness of less than 30 shore at the geometric center, the intermediate layer has a first heel durometer hardness of 30 to 35 shore at the first heel point, the intermediate layer has a first toe durometer hardness of 35 to 40 shore at the first toe point, the intermediate layer has a first heel zone durometer hardness of 35 to 40 at the first heel zone point, and the intermediate layer has a second toe durometer hardness of 40 to 45 shore at the second toe point. 【0081】 (example) (Example 1: Pendulum test: Example club head vs. control club head) A pendulum test was conducted to compare a putter-type club head of an embodiment of the present invention with a control club head. The test was designed to compare the change in smash factor of a putter having a face insert with multiple durometer hardness according to an embodiment of the present invention with a putter face having a single durometer hardness. The embodiment putter had a face insert with multiple durometer hardness, similar to the face inserts in Figures 1 to 5, and had five discrete zones of different hardness. The embodiment putter had a central zone and a first toe zone and a first heel zone located to the toe and heel sides of the central zone. The embodiment putter further had a second toe zone and a second heel zone located to the toe side of the first toe zone and heel side of the first heel zone. The hardness of the central zone was the lowest, Shore 60A. The hardness of the first toe zone and first heel zone was Shore 55D. The hardness of the second toe zone and second heel zone was the highest, Shore 63D. The control club head had a solid metal structure, and its strike face had a single durometer hardness constant profile. 【0082】 The example putter and the control putter were struck at two distances. At each distance, each putter struck the ball five times at five different positions on its striking face. The smash factor was recorded for each strike, and the smash factor was averaged at each of the five positions to obtain a smash factor profile for each of the two distances. Figure 14 shows the smash factor profiles of the example clubhead and the control clubhead for shots struck at a first distance of 10 feet. Figure 15 shows the smash factor profiles of the example clubhead and the control clubhead for shots struck at a second distance of 20 feet. The smash factor profile includes five points: the center point of impact, a point 0.5 inches to the toe (from the center), a point 0.5 inches to the heel (from the center), a point 1.25 inches to the toe (from the center), and a point 1.25 inches to the heel (from the center). Each putter was struck five times at each point. The results of the five shots were averaged to obtain one numerical value for each of the five points. The five points hit correspond to the five discrete zones in the exemplary embodiment described above. 【0083】 As shown in Figures 14 and 15, the example putter had a lower smash factor in center hits for both 10-foot and 20-foot putts compared to the control putter. Furthermore, the example putter had a higher smash factor for hits 1.25 inches to the toe and 1.25 inches to the heel. The example putter showed a more uniform distribution of the smash factor across the entire face compared to the control clubhead, which makes it easier to predict the ball roll distance on mishits. 【0084】 (Example 2: Comparison of a simulated club head with an actual control club head) Comparative tests were conducted to compare the club head of the embodiment according to an embodiment of the present invention with a control club head. In the tests, the smash factor at five different positions on the face of the embodiment club head was mathematically modeled and compared with the smash factor of the control club head measured in a pendulum test. The test results are shown as the percentage decrease in smash factor relative to the central smash factor. The embodiment putter had a face insert having multiple durometer hardnesses, similar to the face inserts in Figures 1 to 5, and had five discrete zones with different hardnesses. The embodiment putter had a central zone and a first toe zone and a first heel zone located on the toe and heel sides of the central zone. The embodiment putter further had a second toe zone and a second heel zone located on the toe side of the first toe zone and on the heel side of the first heel zone. The hardness of the central zone was 30 on the Shore D hardness scale. The hardness of the first toe zone was 37 on the Shore D hardness scale. The hardness of the first heel zone was 31 on the Shore D hardness scale. The hardness of the second toe zone was 41 on the Shore D hardness scale. The hardness of the second heel zone was 38 on the Shore D hardness scale. The control club head had a solid metal structure, and its striking face had a single durometer hardness constant profile. 【0085】 The smash factor of each club head was mathematically predicted at five positions: the center (GC), 0.25 inches to the toe from the center, 0.25 inches to the heel from the center, 0.5 inches to the toe from the center, and 0.5 inches to the heel from the center. These smash factor positions correspond to the stiffness zones mentioned above. 【0086】 As shown in Table 1 below, the example club head demonstrated a more stable smash factor across the entire face compared to the control club head. Therefore, the example club head with an insert having multiple durometer hardness according to an embodiment of the present invention provides more stable ball speed and makes the roll distance more predictable compared to a club head without an insert having multiple durometer hardness. 【0087】 [Table 1]

Claims

[Claim 1] It is a putter-type club head, A body having a toe end, a heel end opposite to the toe end, a front end, a rear end opposite to the front end, an upper part, and a lower part opposite to the upper part, The front surface of the front end, and the front recess extending from the front surface toward the rear end, The front recess is positioned and includes a face insert having a geometric center, The face insert comprises a face plate, an intermediate layer, and an adhesive layer. The aforementioned intermediate layer is The central zone is formed of a central zone material having a central zone hardness of 28-32 on the Shore D hardness scale, A first toe zone is located between the central zone and the toe end and is formed of a first toe zone material having a first toe zone hardness of 33 to 37 on the Shore D hardness scale, A putter-type club head comprising: a first heel zone located between the central zone and the heel end, and formed of a first heel zone material having a first heel zone hardness of 30 to 35 on the Shore D hardness scale. [Claim 2] A second toe zone located between the first toe zone and the toe end, A second heel zone located between the first heel zone and the heel end, The first toe zone is adjacent to the central zone, The putter-type club head according to claim 1, wherein the first heel zone is adjacent to the central zone. [Claim 3] The second toe zone is formed of a second toe zone material having a second toe zone hardness of 35 to 42 on the Shore D hardness scale. The putter-type club head according to claim 2, wherein the second heel zone is formed of a second heel zone material having a second heel zone hardness of 35 to 42 on the Shore D hardness scale. [Claim 4] The aforementioned intermediate layer is formed of PEBAX® material. The putter-type club head according to claim 3, wherein the face plate is formed of an aluminum material. [Claim 5] The faceplate has a thickness of less than 0.050 inches. The putter-type club head according to claim 3, wherein the intermediate layer has a thickness of 0.10 to 0.25 inches. [Claim 6] It is a putter-type club head, A body having a toe end, a heel end opposite to the toe end, a front end, a rear end opposite to the front end, an upper part, and a lower part opposite to the upper part, The front surface, and the front recess located on the front surface, A face insert having a geometric center, The face insert comprises a face plate, an intermediate layer, and an adhesive layer. The faceplate is made of a metal material and completely covers the intermediate layer and the adhesive layer so that no portion of the intermediate layer and the adhesive layer is visible when the intermediate layer and the adhesive layer are located within the front recess. The faceplate forms a continuous front surface which is configured to form a part of the front surface and to collide with the golf ball. The aforementioned intermediate layer comprises a central zone, a first toe zone, a first heel zone, a second toe zone, and a second heel zone. The central zone comprises a central zone toe surface and a central zone heel surface, The first toe zone comprises an outer surface of the first toe zone and an inner surface of the first toe zone, The first heel zone comprises an outer surface of the first heel zone and an inner surface of the first heel zone, The second toe zone comprises an outer surface of the second toe zone and an inner surface of the second toe zone, The second heel zone comprises an outer surface of the second heel zone and an inner surface of the second heel zone, The central zone toe surface abuts against the inner surface of the first toe zone, and the central zone heel surface abuts against the inner surface of the first heel zone. The outer surface of the first heel zone abuts against the inner surface of the second heel zone, and the outer surface of the first toe zone abuts against the inner surface of the second toe zone. The aforementioned central zone has a central durometer hardness of 28 to 32 on the Shore D hardness scale. The first toe zone has a first toe zone durometer hardness of 33 to 37 on the Shore D hardness scale. The first heel zone has a first heel zone durometer hardness of 30 to 35 on the Shore D hardness scale. The second toe zone has a second toe zone durometer hardness of 35 to 42 on the Shore D hardness scale, The second heel zone is a putter-type club head having a second heel zone durometer hardness of 35 to 42 on the Shore D hardness scale. [Claim 7] The aforementioned intermediate layer comprises a third heel zone and a third toe zone, The third heel zone comprises an outer surface of the third heel zone and an inner surface of the third heel zone, The third toe zone comprises an outer surface of the third toe zone and an inner surface of the third toe zone, The inner surface of the third heel zone is in contact with the outer surface of the second heel zone, The inner surface of the third toe zone is in contact with the outer surface of the second toe zone, The third heel zone has a third heel zone durometer hardness of 38 to 47 on the Shore D hardness scale. The putter-type club head according to claim 6, wherein the third toe zone has a third toe zone durometer hardness of 38 to 47 on the Shore D hardness scale. [Claim 8] The body comprises a virtual insert midplane perpendicular to the ground plane and passing through the geometric center, The central zone is perpendicular to the front surface, equidistant from the inner surface of the first toe zone and the inner surface of the first heel zone, and includes a central zone centerline extending perpendicular to the front surface. The first heel zone includes a first heel zone centerline that is perpendicular to the front surface and equidistant from the outer surface and inner surface of the first heel zone, The second toe zone includes a second toe centerline that is perpendicular to the front surface and equidistant from the outer surface and inner surface of the second toe zone, The second heel zone includes a second heel zone centerline that is perpendicular to the front surface and equidistant from the outer surface and inner surface of the second heel zone, The third toe zone includes a third toe zone centerline that is perpendicular to the front surface and equidistant from the outer surface and inner surface of the third toe zone, The third heel zone comprises a third heel zone centerline that is perpendicular to the front surface and equidistant from the outer surface and inner surface of the third heel zone, The third toe zone includes a third toe zone centerline that is perpendicular to the front surface and equidistant from the outer surface and inner surface of the third toe zone, The aforementioned central zone center line lies on the same plane as the virtual insert middle surface. The first heel zone midline is 0.20 to 0.30 inches away from the virtual insert midplane. The second tow midline is 0.20 to 0.30 inches away from the virtual insert midplane. The second heel zone midline is 0.45 to 0.55 inches away from the virtual insert midplane. The third toe zone centerline is 0.45 to 0.55 inches away from the virtual insert center surface. The third heel zone midline is 0.65 to 0.75 inches away from the virtual insert midplane. The putter-type club head according to claim 7, wherein the third toe zone midline is 0.65 to 0.75 inches away from the virtual insert midline. [Claim 9] The faceplate has a thickness of 0.005 to 0.050 inches. The putter-type club head according to claim 7, wherein the intermediate layer has a thickness of 0.025 to 0.25 inches. [Claim 10] The aforementioned front surface forms a loft angle of 0 to 8 degrees. The aforementioned body has a weight of 345 to 380 grams. The putter-type club head according to claim 9, wherein the front surface has a maximum height of less than 1.25 inches. [Claim 11] The putter-type club head according to claim 8, wherein the face plate comprises a plurality of horizontal grooves extending in the heel-toe direction. [Claim 12] It is a putter-type club head, A body having a toe end, a heel end opposite to the toe end, a front end, a rear end opposite to the front end, an upper part, and a lower part opposite to the upper part, The front surface, and the front recess located on the front surface, A face insert having a geometric center, It comprises a middle surface perpendicular to the ground surface and passing through the geometric center, The face insert comprises a face plate, an intermediate layer, and an adhesive layer. The faceplate is located on the outside, the adhesive layer is located on the inside, and the intermediate layer is located between the faceplate and the adhesive layer. The face insert further comprises a first heel point, a first toe point, a first heel zone point, and a second toe point. The first heel point is located 0.25 inches horizontally towards the heel from the middle surface. The first toe point is located 0.25 inches horizontally toward the toe from the middle surface. The first heel zone point is located 0.50 inches horizontally towards the heel from the middle surface. The second toe point is located 0.50 inches horizontally toward the toe from the middle surface. The intermediate layer has a central durometer hardness of less than 30 Shore at the geometric center. The intermediate layer has a first heel durometer hardness of 30 to 35 Shore at the first heel point. The intermediate layer has a first toe durometer hardness of 35 to 40 Shore at the first toe point. The intermediate layer has a first heel zone durometer hardness of 35 to 40 at the first heel zone point. The intermediate layer has a second toe durometer hardness of 40 to 45 shore at the second toe point, forming a putter-type club head.

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