Patent Publication Number: US-9889352-B2

Title: Progressive iron set

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 14/626,526, filed on Feb. 19, 2015, currently pending, which is a continuation-in-part of U.S. patent application Ser. No. 13/887,701, to Ines et al., filed on May 6, 2013 and issued as U.S. Pat. No. 8,998,742, the disclosure of which are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention generally relates to sets of iron golf clubs, and more particularly, to sets of iron golf clubs that provide a progressive center of gravity allocation. 
     BACKGROUND OF THE INVENTION 
     In conventional sets of “iron” golf clubs, each golf club includes a shaft with a club head attached to one end and a grip attached to the other end. The club head includes a face for striking a golf ball. The angle between the face and a vertical plane is called “loft.” In general, the greater the loft is of the golf club in a set, the greater the launch angle and the less distance the golf ball is hit. 
     A set of irons generally includes individual irons that are designated as number 3 through number 9, and a pitching wedge. The iron set is generally complimented by a series of wedges, such as a lob wedge, a gap wedge, and/or a sand wedge. Sets can also include a 1 iron and a 2 iron, but these golf clubs are generally sold separately from the set. Each iron has a shaft length that usually decreases through the set as the loft for each golf club head increases, from the long irons to the short irons. The length of the club, along with the club head loft and center of gravity impart various performance characteristics to the ball&#39;s launch conditions upon impact. The initial trajectory of the ball generally extends between the impact point and the apex or peak of the trajectory. In general, the ball&#39;s trajectory for long irons, like the 3 iron, is a more penetrating, lower trajectory due to the lower launch angle and the increased ball speed off of the club. Short irons, like the 8 iron or pitching wedge, produce a trajectory that is substantially steeper and less penetrating than the trajectory of balls struck by long irons. The highest point of the long iron&#39;s ball flight is generally lower than the highest point for the short iron&#39;s ball flight. The mid irons, such as the 5 iron, produce an initial trajectory that is between those exhibited by balls hit with the long and short irons. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a set of golf clubs comprising long irons, mid-irons and short irons. The long irons are defined as having aloft angle (LA1) of between 15 and 25 degrees and have a first center of gravity positioned horizontally from the face center by a first distance. The mid-irons are defined as having loft angle (LA2) of between 26 and 36 degrees and have a second center of gravity positioned horizontally from the face center by a second distance. The short irons are defined as having a loft angle (LA3) of between 37 and 47 degrees and have a third center of gravity positioned horizontally from the face center by a third distance. The first distance and the second distance are preferably similar and the third distance is at least about 30% greater than the first and second distances. Preferably, the first and second distances are between about 1 mm and 3 mm and the third distance is between about 3 mm and 4 mm. Moreover, it is preferred that the third distance is greater than about 15% of the vertical distance of the center of gravity position from the ground. 
     Another aspect of the present invention is having at least 2 long irons, at least 2 mid-irons and at least 2 short irons, wherein each of the long irons has a center of gravity positioned horizontally from the face center that is between about 0 mm and 2.5 mm, each of the mid-irons has a center of gravity positioned horizontally from the face center that is between about 0 mm and 2.5 mm and each of the short irons has a center of gravity positioned horizontally from the face center by about 3 mm to 4 mm. Within this set, it is preferred that the long irons and mid-irons all contain heel and toe weights that are spaced from each other by at least 75% of the blade length and have weight center of gravities that are below the center of gravity for the iron itself. Further it is preferred that at least one of the short irons contains a weight member that has a weight center of gravity that is located above the center of gravity of the iron. Furthermore, the short iron weight member is preferably located on the heel side of the iron, and most preferably, within the hosel of the iron. 
     Another aspect of the present invention is a set of golf clubs comprising a long iron, a mid-iron and a short iron, wherein the center of gravity location for the short irons are greater than the values defined by the line CG−Xfc=0.02(LA)+2, where CG−Xfc is the distance of the center of gravity from the face center in the horizontal direction toward the hosel and LA is loft angle. 
     Still yet another aspect of the present invention is a set of golf clubs comprising at least a long iron, a mid-iron and a short iron, wherein the short iron has a moment of inertia about the shaft axis that falls below the line defined by the linear equation MOI−SA=4.6(LA)+400, wherein MOI−SA is the moment of inertia about the shaft axis and LA is the loft angle. Preferably, the set also includes a very short iron having a moment of inertia about the shaft axis of between 575 kg*mm2 and 600 kg*mm2. It is also preferred that the short iron has a center of gravity height CG−Yg and the CG−Xfc is greater than about 15% of the CG−Yg. 
     Still yet another aspect of the present invention is a set of golf clubs comprising at least a long iron, a mid-iron and a short iron, wherein blade length throughout the set is approximately constant and the CG−Xfc is progressively increasing from the long iron to the short iron. The set preferably has a constant blade length that is between about 70 and 85 mm, and more preferably, about 75 to 80 mm. In a preferred embodiment, the CG−Xfc increases from less than 2 mm in the long iron to about 3 mm in the short iron. Preferably, the toe height is progressively increasing through the set such that the toe height for the long iron is less than the mid iron, which is less than the short iron. Preferably, the toe height increases through the set from less than about 51 mm to greater than about 55 mm. 
     The present invention is also directed to a set of golf clubs that have a substantially constant blade length through the set, but scoreline width progressively decreases through the set. Thus, the scoreline width for the long iron is greater than the scoreline width for the mid iron, which is greater than the scoreline width for the short iron. Also, within this set, the scoreline to toe width progressively increases through the set. Thus, the scoreline to toe width for the long iron is less than scoreline to toe width for the mid iron, which is less than the scoreline to toe width for the short iron. 
     Another aspect of the present invention is to create a set of irons that have hosels that are easy to bend at the bottom section thereof. More particularly, the hosels have a bottom hosel section having a bending force that is less than 75% of the bending force for the upper hosel portion. This can be achieved by including a hollow section at the bottom of the hosel having a larger diameter than the hosel bore or through a local annealing process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a back view of a long iron according to the present invention; 
         FIG. 2  is a back view of a mid-iron according to the present invention; 
         FIG. 3  is a back view of a short iron according to the present invention; 
         FIG. 4  is a back view of another embodiment of a short iron according to the present invention; 
         FIG. 5  is a graph depicting the center of gravity of a set of irons according to the present invention; 
         FIG. 6  is a graph depicting the moment of inertia about the shaft axis for a set of irons according to the present invention; 
         FIG. 7  is a back view of another embodiment of a short iron according to the present invention; 
         FIG. 8  is an exploded view of a long iron construction according to the present invention; 
         FIG. 9  is an exploded view on a short iron according to the present invention; 
         FIG. 10  is a close up view of a hosel of a short iron according to another embodiment of the present invention; 
         FIG. 11  is a portion of a long iron according to another embodiment of the present invention; 
         FIG. 12  is a portion of a mid-iron according to another embodiment of the present invention; 
         FIG. 13  is a portion of a long iron according to another embodiment of the present invention; 
         FIG. 14  is a portion of a long iron according to another embodiment of the present invention; 
         FIG. 15  is a portion of a long iron according to another embodiment of the present invention; 
         FIG. 16  is a perspective view of a long iron according to another embodiment of the present invention; 
         FIG. 17  is an insert for a long iron according the embodiment set forth in  FIG. 16 ; 
         FIG. 18  is a front view of a long iron according to another embodiment of the present invention; 
         FIG. 19  is a back view of an iron according to another embodiment of the present invention; and 
         FIG. 20  is a back view of an iron according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As illustrated in the accompanying drawings and discussed in detail below, the present invention is directed to an improved set of iron-type golf clubs, wherein the golf clubs have a center of gravity distribution that enables the player to hit more precise shots than conventional golf clubs. 
     Referring to  FIG. 1 , a long iron club in the set includes a club head  10  attached to a shaft (not shown) in any manner known in the art, at a hosel  20 . The long irons of the present invention have a loft of between about 15 and 25 degrees as is well known in the art. Club head  10  includes, generally, the hosel  20 , a striking or hitting face and a back portion that can be cavity backed or muscle backed as is well known in the art. The club head also has a heel  12 , a toe  14 , a top line  22  and a sole  24 . As is well know in the art, the club head  10  and hosel  20  are designed such that the club has a center of gravity CG that is located between the toe  14  and heel  12  and between the top line  22  and the sole  24 , which will be discussed in more detail below. 
     In an embodiment of the present invention, the long iron shown in  FIG. 1  also includes a plurality of weight members  32  and  34 . The weight members may be embedded into a lower chamber or cavity as set forth in detail in U.S. Pat. No. 8,157,673, which is incorporated by reference in its entirety since the patent is entirely directed to the weight members used in the preferred type of construction, as set forth in FIGS. 1-13 and 25-40, and the frequencies of the preferred irons that can be made thereby, as set forth in FIGS. 14-24. Also, as shown in  FIG. 1  herein, the heel weight  34  can be preferably inserted into an aperture machined into the sole  24  adjacent the heel  12 . As shown, the weight aperture can be formed to be coextensive with the shaft axis such that the weight  34  is located such that it is intersected by shaft axis SA. Alternatively, the weight aperture can be formed into the heel  12  adjacent the sole  24 , but would still be intersected by the shaft axis SA. In the preferred embodiment, the weight members  32  and  34  have a greater density than the material used to form the iron head  10  and preferably a density of greater than 2 times the density of the iron head  10 . Most preferably the weight members  32  and  34  have a density of about 17 g/cc. 
     In the iron head construction, the weight members  32  and  34  are sized and positioned to optimize the irons moment of inertia (MOI) about the vertical axis (VA) and the MOI about the shaft axis (SA). Preferably, the long iron weight members  32  and  34  are each between about 10 g and 40 g. Combined, the weight members  32  and  34  should comprise greater than about 10% of the total body weight. Preferably, the weight members  32  and  34  for the long irons are located such that the weight CGw is located below the club CG in the vertical direction. More preferably, the weight members  32  and  34  each have a CGw1 and CGw2, respectively, that is between about 30% and 75% of the CG−Yg of the club. Still further, the CGw1 and CGw2 are preferably located a distance apart that is greater than 50% of the blade length of the club. More preferably, the CGw1 and CGw2 are located at least about 75% of the blade length away from each other to maximize MOI−Y. The iron head  10 , including the weight members  32  and  34 , is constructed such that the CG is also allocated in an optimal position relative to the face center and the shaft axis. The details of the CG locations of the irons within the set will be discussed in more detail below. 
     As shown in  FIG. 2 , a mid-iron  110  according to the present invention has a loft of between about 26 and 36 degrees and includes, generally, the hosel  120 , a striking or hitting face and a back portion that can be cavity backed or muscle backed as is well known in the art. The club head also has a heel  112 , a toe  114 , a top line  122  and a sole  124 . As is well known in the art, the club head  110  and hosel  120  are designed such that the club has a center of gravity CG that is located between the toe  114  and heel  112  and between the top line  122  and the sole  124 , which will be discussed in more detail below. 
     In an embodiment of the present invention, the mid-iron shown in  FIG. 2  also includes a plurality of weight members  132  and  134 . The weight members may be embedded into a lower chamber or cavity as set forth in detail in U.S. Pat. No. 8,157,673, which is incorporated by reference in its entirety since the patent is entirely directed to the weight members used in the preferred type of construction, as set forth in FIGS. 1-13 and 25-40, and the frequencies of the preferred irons that can be made thereby, as set forth in FIGS. 14-24. Also, as shown in  FIG. 2  herein, the heel weight  134  can be preferably inserted into an aperture machined into the sole  124  adjacent the heel  112 . As shown, the weight aperture can be formed to be coextensive with the shaft axis such that the weight  134  is located in a location where it is intersected by shaft axis SA. Alternatively, the weight aperture can be formed into the heel  112  adjacent the sole  124 , but would still be intersected by the shaft axis SA. In the preferred embodiment, the weight members  132  and  134  have a greater density than the material used to form the iron head  110  and preferably a density of greater than 2 times the density of the iron head  110 . More preferably the weight members  132  and  134  have a density of about 14 to 17 g/cc. Most preferably the weight members  132  and  134  have different densities, wherein the density of the heel weight  134  is less than the density of the toe weight  132 . Preferably, the density of the heel weight  134  and the density of the toe weight  132  are about 14 g/cc and 17 g/cc, respectively. 
     In the iron head construction, the weight members  132  and  134  are sized and positioned to optimize the iron&#39;s moment of inertia (MOI) about the vertical axis (VA) and the MOI about the shaft axis (SA). Preferably, the mid-iron weight members  132  and  134  are each between about 20 g and 50 g. Combined, the weight members  132  and  134  should comprise greater than about 15% of the total body weight. Preferably, the weight members  132  and  134  for the mid-irons are located such that at least one of the weight CGw is located below the club CG in the vertical direction. More preferably, the weight member  132  preferably has a CGw3 that is between about 50% and 90% of the CG−Yg of the club and the weight member  134  has a CGw4 that is approximate or greater than CG−Yg. Still further, the CGw3 and CGw4 are preferably located a distance apart that is greater than 50% of the blade length of the club. More preferably, the CGw3 and CGw4 are located at least about 50% and less than 80% of the blade length away from each other to optimize MOI−Y. The iron head  110 , including the weight members  132  and  134 , is constructed such that the CG is allocated in an optimal position relative to the face center and the shaft axis. The details of the CG locations of the irons within the set will be discussed in more detail below. 
       FIGS. 3 and 4  depict alternate embodiments of short irons according to the present invention  210  and  310 , respectively. The iron short iron according to the present invention has a loft of between 37 and 47 degrees. The iron  210  includes a hosel  220 , toe  214 , heel  212 , topline  222  and sole  224 . The iron  210  is constructed such that it has a center of gravity CG as discussed in more detail below. The iron  310  includes a hosel  320 , toe  314 , heel  312 , topline  322  and sole  324 . The iron  310  may have a heel weight member  334  located in the bottom portion of the hosel  320  such that it is intersected by the shaft axis SA. Preferably, the heel weight  334  has a specific gravity greater than the iron material, and more preferably, greater than about 2 times the specific gravity of the iron material. Preferably, the density of the heel weight is about 17 g/cc. Still further, the weight member  334  has a center of gravity CGw5 that is located approximate or above the club CG in the vertical direction and is located a distance from the club CG that is greater than about 40% of the club blade length. Also, it is preferred that there is only a single high density weight member or no high density weight members such that the short irons  210  and  310  are constructed in a manner that they have a center of gravity CG as discussed in more detail below. 
     In accordance with an aspect of the present invention, the inventive iron golf clubs are designed to have progressive centers of gravity as set forth in  FIG. 5 , for example and which is merely illustrative of a preferred embodiment of the present invention set of golf clubs, and is not to be construed as limiting the invention, the scope of which is defined by the appended claims. Each inventive iron golf club is designed to hit golf balls a prescribed distance in the air, and to stop on the green or fairway in a predictable manner. 
     Tables I and II provides exemplary, non-limiting dimensions for the various measurements of golf clubs according to the prior art and to the Example of the invention, respectively. It is fully intended that all of the dimensions set forth below can be adjusted such that the overall objective of the individual irons in met. As a non-limiting example, a 3 iron according to the invention can be made with a loft of 20-22 degrees to adjust the angle of descent and remain within the scope of the present invention. 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
               
             
               
                 TABLE I 
               
               
                   
               
               
                 Club Number 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
                 P 
                 W 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 loft 
                 19 
                 21 
                 24 
                 27 
                 31 
                 35 
                 39 
                 43 
                 47 
                 51 
               
               
                 CG-Yg 
                 19.4 
                 18.9 
                 18.6 
                 18.5 
                 18.3 
                 18.2 
                 18.3 
                 18.1 
                 18.0 
                 17.8 
               
               
                 CG-Bsa 
                 36.0 
                 35.9 
                 35.7 
                 35.7 
                 35.6 
                 35.7 
                 35.4 
                 35.4 
                 35.4 
                 35.0 
               
               
                 CG-Zth 
                 −7.8 
                 −7.6 
                 −8.0 
                 −8.2 
                 −8.9 
                 −9.8 
                 −9.9 
                 −10.6 
                 −12.0 
                 −12.9 
               
               
                 CG-Xfc 
                 2.49 
                 2.40 
                 2.38 
                 2.30 
                 2.20 
                 2.25 
                 2.46 
                 2.31 
                 2.30 
                 2.5 
               
               
                 MOI-X 
                 46 
                 47 
                 49 
                 50 
                 51 
                 54 
                 66 
                 68 
                 71 
                 73 
               
               
                 MOI-Y 
                 231 
                 233 
                 238 
                 242 
                 248 
                 262 
                 270 
                 276 
                 293 
                 296 
               
               
                 MOI-Z 
                 262 
                 265 
                 268 
                 271 
                 274 
                 284 
                 298 
                 300 
                 310 
                 306 
               
               
                 MOI-SA 
                 491 
                 493 
                 505 
                 522 
                 547 
                 562 
                 570 
                 588 
                 622 
                 634 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
               
               
             
               
                 TABLE II 
               
               
                   
               
               
                 Club Number 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
                 P 
                 W 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 loft 
                 21 
                 24 
                 27 
                 30 
                 34 
                 38 
                 42 
                 46 
                 50 
               
               
                 CG-Yg 
                 18.7 
                 18.5 
                 18.6 
                 18.6 
                 18.6 
                 19.4 
                 19.2 
                 19.1 
                 18.7 
               
               
                 CG-Bsa 
                 35.7 
                 35.6 
                 35.6 
                 35.6 
                 35.3 
                 35.1 
                 35.3 
                 34.2 
                 34.1 
               
               
                 CG-Zth 
                 −7.5 
                 −7.8 
                 −8.2 
                 −8.5 
                 −9.1 
                 −9.9 
                 −10.8 
                 −11.3 
                 −12.1 
               
               
                 CG-Xfc 
                 2.4 
                 2.5 
                 2.4 
                 2.4 
                 2.7 
                 3.3 
                 3.0 
                 4.1 
                 4.0 
               
               
                 MOI-X 
                 46.2 
                 47.8 
                 49.3 
                 49.8 
                 51.9 
                 62.4 
                 66.0 
                 69.3 
                 73.0 
               
               
                 MOI-Y 
                 238.3 
                 239.7 
                 243.2 
                 252.6 
                 263.5 
                 253.3 
                 258.4 
                 273.5 
                 279.5 
               
               
                 MOI-Z 
                 268.1 
                 269.2 
                 271.7 
                 278.6 
                 286.2 
                 279.7 
                 280.7 
                 290.0 
                 290.3 
               
               
                 MOI-SA 
                 492.7 
                 504.3 
                 521.8 
                 539.6 
                 556.0 
                 555.7 
                 580.1 
                 578.4 
                 590.3 
               
               
                   
               
            
           
         
       
     
     Referring to the data above and the graph in  FIG. 5 , it is clear that in the irons according to the present invention the center of gravity is located a distance away from the face center CG−Xfc in a manner that is significantly different than with the prior art golf clubs. The face center is defined as the location that is in the middle of the scorelines and half way between the leading edge and the topline of the club. In the prior art golf clubs, the CG−Xfc remains substantially constant through the set. In general, the CG−Xfc in the prior art golf clubs is located between about 2 to 2.5 mm away from the face center towards the heel of the golf club (about 0.1 inch). In the irons according to the present invention, the CG−Xfc for the short irons range from about 40% to 60% further away from the face center than the long irons. More particularly, in the inventive example above and as shown in  FIG. 5 , the CG−Xfc remains approximately constant at about 2.4 mm from the face center through the long irons and the mid-irons. All of the long irons (3 and 4) have a CG−Xfc that is within 15% of each other. All of the mid-irons (5, 6, and 7) have a CG−Xfc that is within 15% of each other. Further, all of the long irons (3 and 4) have a CG−Xfc that is within 15% of all of the mid-irons (5, 6, and 7). However, the short irons (8-W) have CGs that are substantially closer to the hosel or, in other words, substantially further away from the face center in the x (horizontal) direction. In fact, all of the example short irons have a CG−Xfc that is at least 40% greater than the CG−Xfc for the long irons. Preferably, all of the short irons according to the invention have a CG−Xfc that is at least 30% greater than the long irons and the mid-irons. More preferably, all of the short irons of the present invention have a CG−Xfc that is between 35% and 70% greater than the long irons and the mid-irons. 
     Moreover, as shown in  FIG. 5 , the CG−Xfc of the irons according to the present invention varies through the set according to an exponential curve when plotted versus loft angle. As shown, in the irons according to the prior art, the CG−Xfc remains substantially constant, and thus, the CG−Xfc is substantially linear with no slope. Conversely, in the irons according to the present invention, the CG−Xfc remains substantially constant for long irons and mid-irons and then significantly increases for the short irons. Thus, the best fit equation to describe the relationship of the CG−Xfc according to loft is a second order polynomial. Preferably, the irons according to the present invention have a CG−Xfc for the short irons that are greater than the values defined by the line CG−Xfc=0.02(LA)+2. 
     Still further, the distance of the center of gravity to the ground CG−Yg remains similar for the golf clubs in the prior art and in the set according to the present invention. However, for the example set according to the present invention, the CG−Xfc is greater than 15% of CG−Yg for the short irons. For this example, the CG−Xfc ranges from about 15% to 20% of the CG−Yg for the short irons. Thus, the relationship of CG−Xfc to CG−Yg is substantially different than in the prior art golf clubs. 
     Referring to Table I and Table II above, the relationship of the moment of inertia about the shaft axis (MOI−SA) is substantially different between the prior art and the inventive golf clubs. In the very short irons, irons having a loft of between 45 and 52 degrees, the MOI−SA in the prior art is greater than 600 kg*mm2 and closer to about 625 kg*mm2. However, in the inventive irons set forth herein, the MOI−SA for the very short irons is less than 600 kg*mm2 and more preferably between 575 kg*mm2 and 600 kg*mm2. As set forth in  FIG. 6 , the MOI−SA for the prior art is best represented by a linear equation which is approximately MOI−SA=4.6LA+400. On the other hand, the MOI−Sa for the irons according to the present invention are best represented by a second degree polynomial equation. As shown, the MOI−SA for the short irons, including the very short irons, all fall below the linear equation of the prior art. 
     As set forth in Table II, the center of gravity distance from the ground CG−Yg within the set should be set to assist with the creation of the preferred flight paths. Options can include, for example, lowering the center of gravity of the long irons through the use of inserts formed from a material having a specific gravity of greater than 10 g/cc such as tungsten or a tungsten alloy. Additionally, the hosel of the long irons can be comprised of a material having a specific gravity of less than 7 g/cc such as titanium, aluminum or alloys thereof. Conversely, high specific gravity materials may be employed within the topline portion of the short irons to raise the center of gravity. 
     Referring to  FIG. 7 , the short irons  310  according to the present invention, may employ a heel weight member  334  located in the bottom portion of the hosel  320  that is threaded in using a threaded section  336 , such that it is intersected by the shaft axis SA. Preferably, the heel weight  334  has a specific gravity greater than the iron material, and more preferably, greater than about 2 times the specific gravity of the iron material. Preferably, the density of the heel weight is about 17 g/cc. The iron  310  may also include a low weight insert  332  or an aperture that is formed from the toe section  314  so that the CG−Xfc is formed closer to the shaft axis. Preferably, the low weight insert  332  would have a specific gravity of less than the specific gravity of the iron material, and more preferably, about half of the specific gravity of the iron material or less. The low weight insert may be formed from a low specific gravity metal such as aluminum or an elastomeric material. 
       FIG. 8  is an exploded view of the components forming the long iron  10  as shown in  FIG. 1 . The long iron can be formed by forging the body  10 , including a weight pocket  18  adjacent the toe section  14 . After the body  10  is formed, an aperture can be formed in the sole  24 , near the heel  12 , such that a weight insert  32  can be securely fastened therein by a press fit, welding or adhesive. After the toe weight  32  is attached in the weight pocket  18 , a back panel  16  can be secured to the body  10 . Preferably, the back panel and the body are formed from the same materials such that they can be welded together. 
     Referring to  FIGS. 9 and 10 , the short irons according to the present invention may be formed by forging the body  310 . The body may include a back panel welded to the body as set forth in  FIG. 8 , but may be solid. The weight member  334  is preferably formed with a threaded portion  336  and is threaded into the bottom of the hosel  320 . Alternatively, as shown in  FIG. 10 , a weight member  334  may be inserted into the hosel  320  and then a compressive force can be applied to the perimeter of the hosel  320  to form a crimped section  338  that retains the weight member securely in the hosel  320 . The diameter of the crimped section  338  of the hosel  320  should be greater than 80% of the hosel diameter and more preferably between 90% and 95% of the hosel diameter. 
     Referring to  FIG. 11 , in an alternate embodiment of the present invention, the club head  10  can be formed by forging the body with weight pads  32 . Thus, in this embodiment, the weight members  32  are integrally formed with and attached to the back portion of the face. The back panel  16  as set forth above can then be welded over the weight member  32 . This construction method may be preferred for the long irons, mid irons or short irons of the present invention. However, referring to  FIGS. 11 and 12 , if the long irons and mid irons are formed according to this method, it is preferred that the weigh member  32  for the mid irons is located adjacent the face stabilizing bar  38  for the mid-irons and adjacent the sole  24  for the long irons. In this manner, the CG−Yg is designed to be relatively lower in the long irons than in the mid-irons. Also, as shown in  FIG. 12 , the weight member  32  can be formed into multiple portions  32 A and  32 B that are preferably located on opposite sides of the CG to provide a relatively high MOI−Y. The CG location through the set can also be adjusted by providing for a variable face thickness above the stabilizing bar  38 . The upper back wall  48  can be designed a depth from the front face such that the upper face thickness through the set increases with loft. For example, the long irons can be designed with an upper face thickness of about 2.1 mm, the mid irons can have an upper face thickness of about 2.4 mm to 2.7 mm and the short irons can have an upper face thickness of about 2.7 mm to 3.5 mm. The perimeter of the upper face  50  can be about 0.05 mm to 0.25 mm thicker that the center portion  48 . Preferably, the upper face thickness is as thick as or thicker than the next club in the set with a lower loft and the upper face thickness of a short iron is at least 50% greater than the upper face thickness of a long iron. 
     Yet another way to design an iron having the CG according to the present invention is to from a body  10  as shown in  FIG. 13 . The head body  10  can be formed by forging the body with a topline  22 , sole portion  24 , toe portion  14 , heel portion  12 , a weigh pocket  18  and a face stabilizing bar  38 . If the member is forged, an aperture  40  can be formed in the face stabilizing bar  38  prior to the attachment of the back panel  16 . Preferably, the aperture is machined into at least a portion of the face stabilizing bar  38 . If the body is cast, the aperture  40  can be formed in the casting and machining can be avoided. Referring to  FIG. 14 , more than one aperture  40  may be desired. Thus, the club  10  may include one or more apertures formed into the face stabilizing bar  38 . Preferably, the apertures are located on the sole side of the face stabilizing bar  38  and are covered by a back panel  16 . In yet another embodiment of the present invention as set forth in  FIG. 15 , the aperture  40  can extend longitudinally from the heel  12  to the toe  14  a distance of greater than about 25% and less than about 50% of the length of the face stabilizing bar  38 . Preferably, the aperture  40  extends through the face stabilizing bar  38  toward the topline by about 50% to about 90%. By forming the aperture  40  such that is extends on both sides of the CG as shown in  FIG. 15 , the MOI−Y can be optimized. Although not shown, similar apertures can be formed in the bottom surface of the topline  22 . 
     Another way to accomplish the progression of the center of gravity CG−Yg through the set according to the present invention is to employ a low weight face insert as shown in  FIGS. 16 and 17 . Referring to  FIG. 16 , the face  16  can be made of different materials throughout the set. For example, the long irons could employ a titanium alloy insert such as Ti 6-4, which has a specific gravity of 4.4 g/cc and the mid-irons and short irons could employ steel faces having a specific gravity of about 7.9 g/cc. By using higher strength steel in the mid-irons, such as 17-4 stainless steel, the faces can be designed thin to reduce weight and by using a softer steel, such as 431 stainless steel, in the short irons, the feel of the short irons can be improved. Also, as shown in  FIG. 17 , a composite insert  42  comprised of multiple layers of prepreg layups  44  may be used. Preferably, a face insert  42  can be located in a thin cavity behind the face material  16  that can be the same material as the body  10 . The insert  42  should extend longitudinally at least about 50% between the heel  12  and the toe  14 . The height of the insert can be varied, but is preferably between at least 10% and 90% of the height of the iron between the sole  24  and the topline  22 . 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
             
               
                 TABLE III 
               
               
                   
               
               
                 Club Number 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
                 P 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 loft 
                 18 
                 21 
                 24 
                 27 
                 31 
                 35 
                 39 
                 43 
                 47 
               
               
                 Blade Length (mm) 
                 76.2 
                 76.2 
                 76.2 
                 76.2 
                 76.2 
                 76.2 
                 76.2 
                 76.2 
                 76.2 
               
               
                 Toe Height (mm) 
                 50.3 
                 50.6 
                 51.0 
                 51.4 
                 51.9 
                 52.4 
                 53.5 
                 54.6 
                 55.9 
               
               
                 Scoreline Width (mm) 
                 52.4 
                 52.2 
                 52.1 
                 52.0 
                 51.8 
                 51.6 
                 51.3 
                 50.9 
                 50.4 
               
               
                 Scoreline to Toe (mm) 
                 17.3 
                 17.4 
                 17.5 
                 17.7 
                 17.9 
                 18.0 
                 18.4 
                 18.8 
                 19.2 
               
               
                 CG-Xfc (mm) 
                 1.9 
                 1.95 
                 1.9 
                 2.2 
                 2.5 
                 2.5 
                 2.5 
                 3.0 
                 3.0 
               
               
                   
               
            
           
         
       
     
     As shown in  FIG. 18  and set forth in Table III above, another embodiment of the present invention includes a set of irons that have a substantially constant Blade Length (BL) throughout the set. The BL is defined at the length from the hosel axis (HA) intersection with the ground plane to the end of the toe. However in this set, the Toe Height (TH) progressively increases through the set. Thus, the TH of the mid iron is greater than the TH of the long iron and the TH of the short iron is greater than the TH of the mid iron and the long iron. The TH is defined as the maximum length from the leading edge to the top of the toe in the plane parallel to the face plane and perpendicular to the scorelines. Preferably, the TH increases by about at least 0.3 mm per club, and most preferably at least 0.4 mm per club. Also, the TH preferably increases at least 1 mm per club (or about 4 degrees of loft) for the short irons and only 0.3-0.6 mm per club for the long and mid irons. 
     Furthermore, even though the BL remains substantially constant through the set, the scoreline width (SLW) progressively decreases through the set and the scoreline to toe width (SLTW) progressively increases through the set. More particularly, the SLW decreases by at least about 0.1 mm per club (or per 4 degrees of loft). Thus, the SLW for the long iron is greater than the SLW for the mid iron and the SLW for the mid iron is greater than the SLW for the short iron. Moreover, because the SLTW progressively increases through the set, the non-grooved toe area increases throughout the set. 
     Still further, in this preferred embodiment of the present invention, the distance of the center of gravity from the face center progressively increases through the set. Thus, CG−Xfc progressively increases from less than 2 mm from the face center in the long irons to about 3 mm from the face center towards the hosel in the short irons. 
     Another aspect of the present invention is to have a bendable hosel by having a localized bend location at the bottom portion of the hosel. Referring to  FIGS. 19 and 20 , an iron  210  according to the present invention includes a hosel  220 , toe  214 , heel  212 , topline  222  and sole  224 . As shown in  FIG. 19 , the hosel  220  includes a bore having a diameter D1 that is substantially the same size as the diameter of the shaft tip to be inserted into the hosel. This section is the upper hosel portion. Preferably, the iron also includes a hollow section in the bottom section of the hosel that has a diameter D2 that is greater than D1. Preferably, D2 is between 5% and 10% greater than D1 such that the hosel is bendable in the bottom section because the wall thickness is less around the bottom section. More particularly, the bending force required to bend the hosel at the bottom section is less than 75% of the bending force required to bend the hosel at upper hosel section. More preferably, the iron  210  has a hosel having a length of about 30 to 50 mm, and the bottom section of the hosel has a length of about 3 to 10 mm. The bottom section with the larger diameter D2 is preferably only about 5% to 20% of the hosel length and the upper hosel section is 80% to 95% of the hosel length. 
     In another embodiment of the present invention, the iron can be hollow or at least partially hollow as shown in  FIG. 20 . In this embodiment, the hosel bore can be open and in fluid communication to the hollow section of the iron. Like in  FIG. 19 , preferably, the hollow section at the bottom of the hosel has a greater diameter than the hosel bore such that the iron hosel is bendable in this section. 
     In yet another embodiment of the present invention, the bottom section of the hosel, i.e. the bottom 5% to 20% of the hosel, is subject to a localized annealing process. The annealing process alters the physical and sometimes chemical properties of a material to increase the ductility of the bottom section of the hosel to make it more workable. Preferably, the annealed section has a bending force that is less than 75% of the bending force of the upper hosel section. The annealing process involves heating the localized area of the hosel to above its glass transition temperature, maintaining a suitable temperature, and then cooling. The hosel annealing process preferably uses an induction heating coil that goes around the bottom section of the hosel. The temperature of the bottom section is increased to about 500° C. to 1000° C., and more preferably to about 800° C. to 850° C. Preferably, once the bottom section of the hosel is heated, it is held at the elevated temperature for about 5 to 20 seconds, and more preferably, for about 10 seconds. Then the iron is cooled. 
     Another aspect of the preferred embodiment of the present invention is to have a consistent feel within the set. Thus, the swing weights of the irons may be constant through the set. Furthermore, the distance from the center of gravity to the shaft axis can be approximately constant through the set or progress through the set inversely to the loft. 
     While it is apparent that the illustrative embodiments of the present invention disclosed herein fulfill the objectives stated above, it is appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Therefore, it will be understood that the appended claims are intended to cover all modifications and embodiments which would come within the spirit and scope of the present invention.