Patent Publication Number: US-9895581-B2

Title: Golf club head

Description:
The present application claims priority on Patent Application No. 2014-072622 filed in JAPAN on Mar. 31, 2014, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a golf club head. 
     Description of the Related Art 
     A wood type, iron type, hybrid type, utility type, and putter type golf club heads or the like are known as a golf club head. A variation in a hit point is inevitably generated in the heads of all the types. A head having high rebound performance at all the hit point positions is preferable. 
     In a head disclosed in Japanese Patent Application Laid-Open No. 2012-5679 (US2011/0319190), a face part includes a thick part located in a middle, and an outer peripheral part located at an outer periphery of the thick part. The thick part includes a central part having the greatest thickness, a first ridge surrounding the central part, and a first valley located between the central part and the first ridge. An object of the invention of the gazette is to provide a head in which a CT value in a hit point other than a sweet spot is almost equal to a CT value in the sweet spot. 
     Japanese Patent Application Laid-Open No. 2010-279847 discloses a hollow golf club head including a face part and a head main part. The head main part includes a fold-like part bent in an approximately U-shaped section. The fold-like part forms a groove-like part in an outer surface of the head. The fold-like part extends to a crown part, a side part, and a sole part along a peripheral edge of a face surface. The fold-like part can decrease the rigidity of the whole head to achieve high rebound performance. 
     Japanese Unexamined Patent Application Publication No. 2013-527008 (US2011/0294599) discloses a hollow head having a stress reduction feature (SRF). The SRF includes a crown side SRF and a sole side SRF. 
     A head structure intended so that a face part is deflected in a well-balanced manner is disclosed in Japanese Patent Application Laid-Open No. 11-114102. In the head, a tangent of a face surface is S 1 ; a face side tangent of a crown face is S 2 ; a face side tangent of a sole surface is S 3 ; an angle between the tangent S 1  and the tangent S 2  is α; an angle between the tangent S 1  and the tangent S 3  is β; and a supplementary angle of the angle β in the tangent S 3  is γ. In the head, α and β are almost equal to each other, or α and γ are almost equal to each other. 
     Japanese Patent Application Laid-Open No. 10-263118 discloses a hollow head including a deformation promoting part. The deformation promoting part increases the deflection of a face part, or increases the relative displacement of the face part to the head. As the deformation promoting part, a thin-walled groove or a penetration groove provided in the face part is disclosed. 
     U.S. Pat. No. 7,582,024 discloses a head including a main body and a face insert. A slot is provided around the main body near the face insert. 
     Japanese Patent Application Laid-Open No. 2003-325709 discloses a golf club head in which a plurality of joint pieces connecting a face wall part and a back face wall part to each other, and a void located between the joint pieces are formed. 
     SUMMARY OF THE INVENTION 
     There is room for an improvement in rebound performance in a peripheral edge part of a face. 
     It is an object of the present invention to provide a golf club head having excellent rebound performance. 
     A preferable first golf club head includes a head body; a face part; and a connecting part. The face part includes a face surface and a face back surface. The connecting part connects the head body and the face part to each other. A peripheral edge of the face back surface is separated from the head body. 
     A preferable second golf club head includes a head body; a face part; and a connecting part. The face part includes a face surface and a face back surface. The connecting part connects the face back surface and the head body to each other. The connecting part is provided at a position separated from a peripheral edge of the face back surface. 
     Preferably, the head body includes a cavity part and a front part disposed in front of the cavity part. Preferably, the connecting part connects the front part and the face back surface to each other. 
     Preferably, the whole peripheral edge of the face back surface is separated from the head body. 
     A preferable third golf club head includes a head body; a face part; and a connecting part. The head body includes a cavity part and a front part disposed in front of the cavity part. The front part connects an upper part of the head body and a lower part of the head body to each other. The connecting part connects the front part and the face part to each other. A peripheral edge of the face part is separated from the head body. 
     Preferably, the whole peripheral edge of the face part is separated from the head body. 
     Preferably, the face part includes a face middle region and a face peripheral region; and the connecting part is provided only in the face middle region. 
     Preferably, an average CT value in the face peripheral region is greater than an average CT value in the face middle region. 
     Preferably, a CT value in a face center is 160 μs or greater and 257 μs or less. 
     Preferably, a head volume is 100 cc or greater and less than 300 cc. 
     Preferably, a CT value in a face center is 160 μs or greater and 257 μs or less. Preferably, a head volume is 100 cc or greater and less than 300 cc. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a golf club head according to a first embodiment; 
         FIG. 2  is a front view of the head of  FIG. 1 , and describes a face surface in a planar view together; 
         FIG. 3  is a top view of the head of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view taken along line F 4 -F 4  of  FIG. 2 ; 
         FIG. 5  is a cross-sectional view taken along line F 5 -F 5  of  FIG. 2 ; 
         FIG. 6  is a perspective view of a head body used for the head of  FIG. 1 ; 
         FIG. 7  is a perspective view of a face part used for the head of  FIG. 1 ; 
         FIG. 8  is a front view of a head according to a second embodiment; 
         FIG. 9  is a perspective view of a face part used for the head of  FIG. 8 ; 
         FIG. 10  is a front view of a head according to a third embodiment; 
         FIG. 11  is a perspective view of a face part used for the head of  FIG. 10 ; 
         FIG. 12  is a cross-sectional view taken along line F 12 -F 12  of  FIG. 10 ; 
         FIG. 13  is a front view of a head according to a fourth embodiment; 
         FIG. 14  is a cross-sectional view taken along line F 14 -F 14  of  FIG. 13 ; 
         FIG. 15  is a cross-sectional view taken along line F 15 -F 15  of  FIG. 13 ; 
         FIG. 16  is an exploded perspective view of a head according to a fifth embodiment; 
         FIG. 17  is a front view of a head according to a sixth embodiment; 
         FIG. 18  is a front view of a head according to a seventh embodiment; 
         FIG. 19  is a front view of a head according to an eighth embodiment; 
         FIG. 20  is a front view of a head according to a ninth embodiment; 
         FIG. 21  is a front view of a head according to a tenth embodiment; 
         FIG. 22  is a front view of a head according to an eleventh embodiment; 
         FIG. 23  is a front view of a head according to a twelfth embodiment; 
         FIG. 24  is a front view of a head according to a thirteenth embodiment; 
         FIG. 25  is an exploded perspective view of the head of  FIG. 24 ; 
         FIG. 26  is a cross-sectional view taken along line F 26 -F 26  of  FIG. 24 ; 
         FIG. 27  is an exploded perspective view of a head according to a fourteenth embodiment; 
         FIG. 28  is a cross-sectional view of a head according to a fifteenth embodiment; 
         FIG. 29  is a front view of a head according to a sixteenth embodiment; 
         FIG. 30  is a front view showing a backup region and a nonbackup region; 
         FIG. 31  shows an image of an FE model showing a perspective view of a head according to Example 1; 
         FIG. 32  shows an image of an FE model showing a face part and a connecting part of Example 1; 
         FIG. 33  shows an image of an FE model showing a head body and a connecting part of Example 1; 
         FIG. 34  shows an image of an FE model showing a top view of a head according to Example 1; 
         FIG. 35  shows an image of an FE model showing a cross-sectional view taken along line F 35 -F 35  of  FIG. 34 ; 
         FIG. 36  shows an image of an FE model showing a perspective view of a head according to Example 2; 
         FIG. 37  shows an image of an FE model showing a head body and a connecting part of Example 2; 
         FIG. 38  shows an image of an FE model showing a perspective view of a head according to Example 3; 
         FIG. 39  shows an image of an FE model showing a face part and a connecting part of Example 3; 
         FIG. 40  shows an image of an FE model showing a head body and a connecting part of Example 3; 
         FIG. 41  shows an image of an FE model showing a top view of a head according to Example 3; 
         FIG. 42  shows an image of an FE model showing a cross-sectional view taken along line F 42 -F 42  of  FIG. 41 ; and 
         FIGS. 43A and 43B  show a simulation image showing a state where the head of Example 3 and a ball collide with each other. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described below in detail based on preferred embodiments with appropriate reference to the drawings. 
       FIG. 1  is a perspective view of a golf club head  2  according to one embodiment of the present invention.  FIG. 2  is a front view of the head  2 . In addition to the front view of the head  2 , a border line BL of a face surface f 1  in a planar view is described in  FIG. 2 .  FIG. 3  is a top view of the head  2 .  FIG. 4  is a cross-sectional view taken along line F 4 -F 4  of  FIG. 2 .  FIG. 5  is a cross-sectional view taken along line F 5 -F 5  of  FIG. 2 .  FIG. 6  is a perspective view of a head body h 1 .  FIG. 6  includes a part of a connecting part Cn 1 .  FIG. 7  is a perspective view of a face part Fp 1 .  FIG. 7  includes a part of the connecting part Cn 1 . 
     The head  2  is a wood type head. The head  2  is a driver head. As described below, the head  2  may be a utility type (hybrid type) head, an iron type head, or a putter type head. 
     The head  2  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The face part Fp 1  includes a peripheral edge f 20 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . 
     The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . As shown in  FIGS. 3 and 6 , the hosel  8  includes a hosel hole  10 . 
     The inside of the head body h 1  is a space. In other words, as shown in  FIGS. 5 and 6 , the head body h 1  includes a cavity part k 1 . The cavity part k 1  is a hollow part. The head  2  is a hollow head. In the present application, the “cavity part” is a concept including a hollow part and a recess part. The cavity part may be a closed space. The cavity part may be an opened space. 
     The head body h 1  includes a front part Fb 1  (see  FIGS. 4, 5, and 6 ). The front part Fb 1  is disposed in front of the cavity part k 1 . The cavity part k 1  is present behind the front part Fb 1 . The front part Fb 1  shields at least a part of a front of the cavity part k 1 . As shown in  FIG. 6 , in the head  2 , the front part Fb 1  blocks the whole front of the cavity part k 1 . The front part Fb 1  is located behind the face part Fp 1 . 
     As in the head  2 , the front part Fb 1  may be located at a foremost position of the head body h 1 . Meanwhile, the front part Fb 1  may not be located at the foremost position of the head body h 1 . For example, the front part Fb 1  may be located behind a forward edge of the head body h 1 . 
     The front part Fb 1  connects an upper part of the head body h 1  and a lower part of the head body h 1  to each other. In the present embodiment, the upper part of the head body h 1  is the crown  4 . In the embodiment, the lower part of the head body h 1  is the sole  6 . The face part Fp 1  is connected to the front part Fb 1  by only the connecting part Cn 1 . 
     The connecting part Cn 1  is integrally molded with the face part Fp 1  and the front part Fb 1 . The integral molding method is lost-wax casting. The connecting part Cn 1  may be joined to the face part Fp 1 . The connecting part Cn 1  may be joined to the front part Fb 1 . In respect of a strength, the joining method is preferably welding. 
     The front part Fb 1  includes a front surface b 1  and a back surface b 2 . The back surface b 2  faces the cavity part k 1 . The connecting part Cn 1  connects the front surface b 1  and the face part Fp 1  to each other. 
     The face part Fp 1  includes a face surface f 1  and a face back surface f 2 . The face surface f 1  is a hitting surface. The face back surface f 2  is opposed to the front surface b 1 . 
     The face part Fp 1  is wholly plate-like. A clearance g 1  is provided between the face part Fp 1  and the front part Fb 1  (see  FIGS. 4 and 5 ). 
     A plurality of score line grooves are formed in the face surface f 1 . These score line grooves are abbreviated in the drawings. 
     The face surface f 1  is a curved surface. The face surface f 1  is a three-dimensional curved surface convexed to the outer side. As in a general wood type head, the face surface f 1  includes a bulge and a roll. 
     In the present embodiment, the face back surface f 2  is a plane. The face back surface f 2  may be a curved surface. For example, the face back surface f 2  may be a curved surface along the face surface f 1 . In Examples to be described below, the face back surface f 2  is a curved surface along the face surface f 1 . 
     The connecting part Cn 1  connects the face back surface f 2  and the front surface b 1  to each other. Except for a portion in which the connecting part Cn 1  is present, the clearance g 1  is present between the face back surface f 2  and the front surface b 1 . 
     As shown in  FIGS. 4 and 5 , the connecting part Cn 1  is solid. The connecting part Cn 1  may be hollow. 
     DEFINITIONS OF TERMS 
     The following terms are defined in the present application. 
     [Base State, Base Perpendicular Plane] 
     A plane VP 1  perpendicular to a level surface H is set (abbreviated in the drawings). A state where a center axis line Z 1  of a shaft hole is included in the plane VP 1  and a head is placed at a specified lie angle and real loft angle on the level surface H is defined as a base state (abbreviated in the drawings). The plane VP 1  is defined as a base perpendicular plane. The specified lie angle and real loft angle are described in, for example, a product catalog. 
     [Toe-Heel Direction] 
     A toe-heel direction is a direction of an intersection line between the base perpendicular plane VP 1  and the level surface H. 
     [Face-Back Direction] 
     A face-back direction is a direction perpendicular to the toe-heel direction and parallel to the level surface H. 
     [Vertical Direction] 
     A vertical direction is a direction perpendicular to the level surface H. 
     [Face Projection Plane] 
     A face projection plane is a plane perpendicular to a face normal line. The face normal line is a straight line passing through a face center Fc and being perpendicular to the face surface f 1 . If the face surface f 1  is a curved surface, a tangent plane in the face center Fc is considered. That is, the face normal line is a straight line being perpendicular to the tangent plane and passing through the face center Fc. 
     [Planar View] 
     A projection image to the face projection plane is defined as a planar view. A face border view described on a lower side in  FIG. 2  is the planar view. In the projection to the face projection plane, the projection direction is the direction of the face normal line. 
     [Up-Down Direction] 
     A straight line extending in the vertical direction is projected on the face projection plane. A direction of the projected straight line is defined as an up-down direction. 
     Therefore, the up-down direction is parallel to the face projection plane. 
     [Face Center Fc] 
     In  FIG. 2 , a border view (face border view) of the face surface f 1  in the planar view is described with the front view of the head  2 . As shown in  FIG. 2 , in the face surface f 1 , a maximum width Wx in the toe-heel direction is determined. Furthermore, a middle position Px of the maximum width Wx in the toe-heel direction is determined. At the position Px, a width Wy of the face surface f 1  in the up-down direction is determined, and a center position Py of the width Wy in the up-down direction is determined. A point at which a position in the toe-heel direction is Px and a position in the up-down direction is Py is defined as a face center Fc. The face center Fc is estimated in the planar view. 
     [Face Middle Region R 1 ] 
     In the face surface f 1  in the planar view, an ellipse A having its center at the face center Fc is defined (see the face border view in  FIG. 2 ). A major axis of the ellipse A is half the width Wx. A minor axis of the ellipse A is half the width Wy. An inner side region of the ellipse A is a face middle region R 1 . The region R 1  is determined in the planar view. 
     [Face Peripheral Region R 2 ] 
     A region other than the face middle region R 1  is a face peripheral region R 2 . The face peripheral region R 2  is located around the face middle region R 1 . The ellipse A divides the face surface f 1  into the face middle region R 1  and the face peripheral region R 2 . An outer edge of the face peripheral region R 2  is the border line BL of the face surface f 1 . The region R 2  is determined in the planar view. 
     [Middle Inner Side Region R 3 ] 
     In the face surface f 1  in the planar view, an ellipse B having its center at the face center Fc is defined (see the face border view in  FIG. 2 ). A major axis of the ellipse B is ¼ of the width Wx. A minor axis of the ellipse B is ¼ of the width Wy. An inner side region of the ellipse B is a middle inner side region R 3 . The region R 3  is determined in the planar view. 
     [Middle Outer Side Region R 4 ] 
     A region located between the ellipse A and the ellipse B is a middle outer side region R 4 . In other words, the middle outer side region R 4  is a portion excluding the middle inner side region R 3  in the face middle region R 1 . The ellipse B divides the face middle region R 1  into the middle inner side region R 3  and the middle outer side region R 4 . The region R 4  is determined in the planar view. 
     [Peripheral Inner Side Region R 5 ] 
     In the face surface f 1  in the planar view, an ellipse C having its center at the face center Fc is defined (see the face border view in  FIG. 2 ). A major axis of the ellipse C is ¾ of the width Wx. A minor axis of the ellipse C is ¾ of the width Wy. A region located between the ellipse C and the ellipse A is a peripheral inner side region R 5 . The region R 5  is determined in the planar view. 
     [Peripheral Outer Side Region R 6 ] 
     A region located outside the ellipse C is a peripheral outer side region R 6 . In other words, the peripheral outer side region R 6  is a portion excluding the peripheral inner side region R 5  in the face peripheral region R 2 . An outer edge of the peripheral outer side region R 6  is the border line BL of the face surface f 1 . The region R 6  is determined in the planar view. 
     [CT Value] 
     A CT value is well known to a person skilled in the art. A characteristic time of the head is referred to as the CT value. The CT value is measured based on the existing Pendulum Test of USGA. The Pendulum Test is described in detail in “Technical Description of the Pendulum Test” attached to “Notice To Manufacturers” issued by USGA on Feb. 24, 2003. The unit of the CT value is μs. Rebound performance tends to be higher as the CT value is larger. 
     [Average CT Value] 
     A two-dimensional xy-coordinate system is defined in the face surface f 1  in the planar view (see the face border view in  FIG. 2 ). A y-axis of the xy-coordinate system is parallel to the up-down direction. An x-axis of the xy-coordinate system is perpendicular to the y-axis. An origin of the xy-coordinate system is the face center Fc. The plus side of an x-coordinate is a heel side. The minus side of the x-coordinate is a toe side. The plus side of a y-coordinate is an upper side. The minus side of the y-coordinate is a lower side (sole side). 
     Measurement points of the CT value are set in the xy-coordinate system. These measurement points are intersection points of lattice lines drawn at intervals of 5 mm (abbreviated in the drawings). The measurement points are determined based on the x-coordinate and the y-coordinate. The measurement points are set at intervals of 5 mm in each of the x-coordinate and the y-coordinate. The x-coordinates (mm) of the measurement points are 5N. N is all integers. The y-coordinates (mm) of the measurement points are 5M. M is all integers. The coordinates (x, y) of the measurement points are (5N, 5M). In each of the x-coordinate and the y-coordinate, the measurement points are set at intervals of 5 mm. For example, if the y-coordinate is 0, the coordinates (x, y) of the measurement points are (0, 0), (5, 0), (10, 0), (15, 0), (20, 0), (−5, 0), (−10, 0), (−15, 0), and (−20, 0) or the like. For example, if the y-coordinate is 5, the coordinates (x, y) of the measurement points are (0, 5), (5, 5), (10, 5), (15, 5), (20, 5), (−5, 5), (−10, 5), (−15, 5), and (−20, 5) or the like. The measurement points are set over the whole range of the face surface f 1 . The CT values are measured in all the measurement points as long as the CT values can be measured. 
     The average CT value is an average value of the CT values in all the measurement points. For example, an average CT value in the face middle region R 1  is an average of the CT values measured in all the measurement points which are present in the face middle region R 1 . 
     An average CT value in the face middle region R 1  is defined as CT 1 . An average CT value in the face peripheral region R 2  is defined as CT 2 . An average CT value in the middle inner side region R 3  is defined as CT 3 . An average CT value in the middle outer side region R 4  is defined as CT 4 . An average CT value in the peripheral inner side region R 5  is defined as CT 5 . An average CT value in the peripheral outer side region R 6  is defined as CT 6 . 
     [Toe Region] 
     A toe region is defined in the face surface f 1  in the planar view. The toe region is a region located on a toe side with respect to the face center Fc. In the face border view of  FIG. 2 , the left side of the y-axis is the toe region. 
     [Heel Region] 
     A heel region is defined in the face surface f 1  in the planar view. The heel region is a region located on a heel side with respect to the face center Fc. In the face border view of  FIG. 2 , the right side of the y-axis is the heel region. 
     [Upper Region] 
     An upper region is defined in the face surface f 1  in the planar view. The upper region is a region located on an upper side with respect to the face center Fc. In the face border view of  FIG. 2 , the upper side of the x-axis is the upper region. 
     [Lower Region] 
     A lower region is defined in the face surface f 1  in the planar view. The lower region is a region located on a lower side with respect to the face center Fc. In the face border view of  FIG. 2 , the lower side of the x-axis is the lower region. 
     As described above, the face part Fp 1  includes the face surface f 1  and the face back surface f 2 . As shown in  FIG. 7 , the face back surface f 2  includes a peripheral edge f 21 . In the present embodiment, the peripheral edge f 21  of the face back surface f 2  is also the peripheral edge f 20  of the face part Fp 1 . The peripheral edge f 21  and the peripheral edge f 20  may not coincide with each other depending on the shape of the peripheral edge of the face part Fp 1 . As shown in  FIG. 7 , the connecting part Cn 1  is provided at a position separated from the peripheral edge f 21 . As shown in  FIG. 7 , the connecting part Cn 1  is provided at a position separated from the peripheral edge f 20 . 
     In the present embodiment, the shape of the connecting part Cn 1  in the planar view is a rectangle. In more detail, the shape of the connecting part Cn 1  in the planar view is a square. 
     As shown in  FIG. 7 , in the head  2 , the whole peripheral edge f 20  is separated from the connecting part Cn 1 . In the head  2 , the whole peripheral edge f 21  of the face back surface f 2  is separated from the connecting part Cn 1 . A part of the peripheral edge f 21  (peripheral edge f 20 ) may be separated from the connecting part Cn 1 . In other words, the connecting part Cn 1  may be joined to a part of the peripheral edge f 21  (peripheral edge f 20 ). In respect of the rebound performance of a face peripheral edge part, 50% or greater of the peripheral edge f 21  (peripheral edge f 20 ) is preferably separated from the connecting part Cn 1 ; 70% or greater of the peripheral edge f 21  (peripheral edge f 20 ) is more preferably separated from the connecting part Cn 1 ; 90% or greater of the peripheral edge f 21  (peripheral edge f 20 ) is still more preferably separated from the connecting part Cn 1 ; and 100% of the peripheral edge f 21  (peripheral edge f 20 ) is yet still more preferably separated from the connecting part Cn 1 . In the head  2 , 100% of the peripheral edge f 21  (peripheral edge f 20 ) is separated from the connecting part Cn 1 . 
     The connecting part Cn 1  is located on the face center Fc side with respect to the peripheral edge f 21 . The connecting part Cn 1  is located in the face middle region R 1 . The whole connecting part Cn 1  is located in the face middle region R 1 . A backup region B 1  (described below) includes the face center Fc. At least a part of the connecting part Cn 1  is located in the middle inner side region R 3 . 
     As described above, the front part Fb 1  of the head body h 1  includes the front surface b 1 . As shown in  FIG. 6 , the front surface b 1  includes a peripheral edge b 11 . 
     As shown in  FIG. 6 , in the head  2 , the peripheral edge b 11  is separated from the connecting part Cn 1 . The whole peripheral edge b 11  is separated from the connecting part Cn 1 . 
     A part of the peripheral edge b 11  may be separated from the connecting part Cn 1 . In other words, the connecting part Cn 1  may be disposed on a part of the peripheral edge b 11 . 
     As shown in  FIG. 5 , the peripheral edge f 21  (peripheral edge f 20 ) is separated from the head body h 1 . The whole peripheral edge f 21  (peripheral edge f 20 ) is separated from the head body h 1 . The peripheral edge f 21  (peripheral edge f 20 ) is separated from the front part Fb 1 . A space is provided behind the peripheral edge f 21  (peripheral edge f 20 ). The space is not connected to the hollow part of the head body h 1 . The space provided behind the peripheral edge f 21  (peripheral edge f 20 ), and the hollow part of the head body h 1  are divided by the front part Fb 1 . The space forms the clearance g 1 . The clearance g 1  is present between the peripheral edge f 21  and the head body h 1 . In the whole peripheral edge f 21 , the clearance g 1  is present between the peripheral edge f 21  and the head body h 1 . The clearance g 1  easily causes the displacement of the peripheral edge f 21 . The face surface f 1  is easily deformed in hitting. A peripheral edge part of the face part Fp 1  has a high degree of freedom of deformation. The peripheral edge part of the face part Fp 1  is once displaced backward by the deformation, and then returned to the front. Since the peripheral edge f 21  is separated from the head body h 1 , the peripheral edge part is easily displaced backward. The deformation of the face part Fp 1  increases rebound performance. In the head  2 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     In respect of the rebound performance of the face peripheral edge part, 50% or greater of the peripheral edge f 21  (peripheral edge f 20 ) is preferably separated from the head body h 1 ; 70% or greater of the peripheral edge f 21  (peripheral edge f 20 ) is more preferably separated from the head body h 1 ; 90% or greater of the peripheral edge f 21  (peripheral edge f 20 ) is still more preferably separated from the head body h 1 ; and 100% of the peripheral edge f 21  (peripheral edge f 20 ) is yet still more preferably separated from the head body h 1 . In the head  2 , 100% of the peripheral edge f 21  (peripheral edge f 20 ) is separated from the head body h 1 . 
     In the head  2 , the connecting part Cn 1  is provided only in the face middle region R 1 . The connecting part Cn 1  is not present in the face peripheral region R 2 . The whole face peripheral region R 2  is not backed up. In the whole face peripheral region R 2 , the clearance g 1  is present on the back side of the face part Fp 1 . Therefore, the face peripheral region R 2  has high rebound performance. 
     As shown in  FIGS. 4 and 5 , the face part Fp 1  is solid. Even if the face part Fp 1  is thin, the solid face part Fp 1  has an excellent strength. The solid face part Fp 1  has an excellent strength even if the backup region B 1  is small. The backup region B 1  will be described below. 
     As shown in  FIGS. 4 and 5 , the face peripheral region R 2  of the face part Fp 1  is solid. Even if the face peripheral region R 2  is thin, the solid face peripheral region R 2  has an excellent strength. The solid face peripheral region R 2  has excellent durability. The face peripheral region R 2  has excellent durability against large deformation. 
     In the head  2 , an average CT value (CT 2 ) in the face peripheral region R 2  is greater than an average CT value (CT 1 ) in the face middle region R 1 . That is, the following relational formula (1) is realized. In the head  2 , the peripheral edge part of the face surface f 1  has excellent rebound performance.
 
CT2&gt;CT1  (1)
 
     In the head  2 , an average CT value (CT 4 ) in the middle outer side region R 4  is greater than an average CT value (CT 3 ) in the middle inner side region R 3 . That is, the following relational formula (2) is realized. A sweet spot of the head  2  is large.
 
CT4&gt;CT3  (2)
 
     In the head  2 , an average CT value (CT 5 ) in the peripheral inner side region R 5  is greater than an average CT value (CT 4 ) in the middle outer side region R 4 . That is, the following relational formula (3) is realized. The sweet spot of the head  2  is large. In the head  2 , the peripheral edge part has excellent rebound performance.
 
CT5&gt;CT4  (3)
 
     In the head  2 , an average CT value (CT 6 ) in the peripheral outer side region R 6  is greater than an average CT value (CT 5 ) in the peripheral inner side region R 5 . That is, the following relational formula (4) is realized. In the head  2 , the peripheral edge part has excellent rebound performance.
 
CT6&gt;CT5  (4)
 
     As described above, in the head  2 , the clearance g 1  is provided between the whole peripheral edge f 21  and the head body h 1 . Therefore, the high rebound performance is achieved in the whole peripheral edge part of the face surface f 1 . 
     As shown in  FIGS. 4 and 5 , the average thickness of the face peripheral region R 2  is smaller than the average thickness of the face middle region R 1 . The thin face peripheral region R 2  facilitates the deformation of the face peripheral region R 2 . The thin face peripheral region R 2  increases the rebound performance of a face peripheral part. 
     [Second Embodiment] 
       FIG. 8  is a front view of a head  20  according to a second embodiment.  FIG. 9  is a perspective view of a face part Fp 1  used for the head  20 .  FIG. 9  is a perspective view of the face part Fp 1  viewed from a back side. A connecting part Cn 1  connected to the face part Fp 1  is also shown in  FIG. 9 . 
     The head  20  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The inside of the head body h 1  is a space. The head  20  is a hollow head. 
     In the head  20 , a peripheral edge f 21  (peripheral edge f 20 ) is separated from the head body h 1 . The whole peripheral edge f 21  (peripheral edge f 20 ) is separated from the head body h 1 . The peripheral edge f 21  (peripheral edge f 20 ) is separated from a front part Fb 1 . A clearance is present between the peripheral edge f 21  (peripheral edge f 20 ) and the head body h 1 . In the whole peripheral edge f 21  (peripheral edge f 20 ), the clearance is present between the peripheral edge f 21  and the head body h 1 . The clearance easily causes the displacement of the peripheral edge f 21 . The clearance easily causes the deformation of a face surface f 1  in hitting. A peripheral edge part of the face part Fp 1  has a high degree of freedom of deformation. The peripheral edge part of the face part Fp 1  is once displaced backward by the deformation, and then returned to the front. The deformation of the face part Fp 1  increases rebound performance. In the head  20 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     The difference between the above-mentioned head  2  and the head  20  is only the connecting part Cn 1 . 
     The connecting part Cn 1  is disposed substantially at the middle of the face part Fp 1 . In the planar view, the center of gravity of the connecting part Cn 1  is located in a face middle region R 1 . In the planar view, the center of gravity of the connecting part Cn 1  is located in a middle inner side region R 3 . In the planar view, the presence region of the connecting part Cn 1  includes a face center Fc. 
     In the head  20 , the connecting part Cn 1  has an oblong shape. The length of the connecting part Cn 1  in a toe-heel direction is greater than the length of the connecting part Cn 1  in an up-down direction. The connecting part Cn 1  which is longer in the toe-heel direction stably supports the face part Fp 1 . 
     The connecting part Cn 1  does not inhibit the rebound performance on the lower side of the face surface f 1 . In the head  20 , the rebound performance on the lower side of the face surface f 1  is high. The connecting part Cn 1  does not inhibit the rebound performance on the upper side of the face surface f 1 . In the head  20 , the rebound performance on the upper side of the face surface f 1  is high. 
     [Third Embodiment] 
       FIG. 10  is a front view of a head  30  according to a third embodiment.  FIG. 11  is a perspective view of a face part Fp 1  used for the head  30 .  FIG. 12  is a cross-sectional view taken along line F 12 -F 12  of  FIG. 10 . 
     The head  30  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The inside of the head body h 1  is a space. As shown in  FIG. 12 , the head body h 1  includes a cavity part k 1 . The head  30  is a hollow head. 
     In the head  30 , a peripheral edge f 21  of a face back surface f 2  is separated from the head body h 1 . The whole peripheral edge f 21  is separated from the head body h 1 . The peripheral edge f 21  is separated from a front part Fb 1 . A clearance g 1  is present between the peripheral edge f 21  and the head body h 1 . In the whole peripheral edge f 21 , the clearance g 1  is present between the peripheral edge f 21  and the head body h 1 . The clearance g 1  easily causes the displacement of the peripheral edge f 21 . A face surface f 1  is easily deformed in hitting. A peripheral edge part of the face part Fp 1  has a high degree of freedom of deformation. In the head  30 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     The difference between the above-mentioned head  2  and the head  30  is only the connecting part Cn 1 . 
     The connecting part Cn 1  is disposed on the upper side of the face part Fp 1 . In the planar view, the presence region of the connecting part Cn 1  does not include a face center Fc. In the planar view, the center of gravity of the connecting part Cn 1  is located in the upper region. In the planar view, the center of gravity of the connecting part Cn 1  is located in a face peripheral region R 2 . In the planar view, the center of gravity of the connecting part Cn 1  is located in the peripheral inner side region R 5 . In the planar view, the upper region includes the whole connecting part Cn 1 . 
     In the head  30 , the connecting part Cn 1  has an oblong shape. The length of the connecting part Cn 1  in a toe-heel direction is greater than the length of the connecting part Cn 1  in an up-down direction. The strength of the connecting part Cn 1  is improved by increasing the length of the connecting part Cn 1  in the toe-heel direction. 
     Since the connecting part Cn 1  is disposed on the upper side, the displacement on the lower side of the face surface f 1  is large. That is, the connecting part Cn 1  disposed on the upper side allows large displacement on the lower side of the face surface f 1 . The connecting part Cn 1  can effectively increase rebound performance on the lower side of the face surface f 1 . In the head  30 , the rebound performance on the lower side of the face surface f 1  is high. 
     The disposal of the connecting part Cn 1  is not limited. For example, contrary to the head  30 , the connecting part Cn 1  may be disposed on the lower side. For example, the whole connecting part Cn 1  may be disposed in the lower region. The connecting part Cn 1  disposed on the lower side allows large displacement on the upper side of the face surface f 1 . The connecting part Cn 1  can effectively increase rebound performance on the upper side of the face surface f 1 . The large displacement on the upper side of the face surface f 1  increases a loft angle. Therefore, a high launch angle can be achieved. The high launch angle contributes to an increase in a flight distance. 
     [Fourth Embodiment] 
       FIG. 13  is a front view of a head  40  according to a fourth embodiment.  FIG. 14  is a cross-sectional view taken along line F 14 -F 14  of  FIG. 13 .  FIG. 15  is a cross-sectional view taken along line F 15 -F 15  of  FIG. 13 . 
     The head  40  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The hosel  8  includes a hosel hole  10 . The inside of the head body h 1  is a space. As shown in  FIGS. 14 and 15 , the head body h 1  includes a cavity part k 1 . The head  40  is a hollow head. 
     In the head  40 , a peripheral edge f 21  of a face back surface f 2  is separated from the head body h 1 . The whole peripheral edge f 21  is separated from the head body h 1 . The peripheral edge f 21  is separated from a front part Fb 1 . A clearance g 1  is present between the peripheral edge f 21  and the head body h 1 . In the whole peripheral edge f 21 , the clearance g 1  is present between the peripheral edge f 21  and the head body h 1 . The clearance g 1  easily causes the displacement of the peripheral edge f 21 . A face surface f 1  is easily deformed in hitting. A peripheral edge part of the face part Fp 1  has a high degree of freedom of deformation. The deformation of the face part Fp 1  increases rebound performance. In the head  40 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     The difference between the above-mentioned head  2  and the head  40  is only the thickness of the front part Fb 1 . In the head  40 , the front part Fb 1  is thin. 
     In hitting, in addition to the face part Fp 1 , the front part Fb 1  can also be deformed. That is, in hitting, the front part Fb 1  is deflected. The thin front part Fb 1  can be easily deformed. In hitting, a middle part of the front part Fb 1  is once displaced backward, and then returned to the front. The deformation of the front part Fb 1  contributes to an improvement in rebound performance. 
     On the face surface f 1 , displacement A caused by the separation of the face surface f 1  from the head body h 1  and displacement B caused by the deformation of the front part Fb 1  are generated. A synergistic effect is exhibited by the displacement A and the displacement B. The synergistic effect increases the rebound performance. The synergistic effect achieves both the rebound performance of a face middle region R 1  and the rebound performance of a face peripheral region R 2 . The synergistic effect can increase the rebound performance of the whole face surface f 1 . 
     Although the displacement A is not generated in a portion backed up by the connecting part Cn 1 , the displacement B is generated. The displacement B increases the rebound performance of a backup region B 1  (described below). 
     The connecting part Cn 1  is disposed substantially at the middle of the face part Fp 1 . In the planar view, the center of gravity of the connecting part Cn 1  is located in the face middle region R 1 . In the planar view, the center of gravity of the connecting part Cn 1  is located in a middle inner side region R 3 . In the planar view, the presence region of the connecting part Cn 1  includes a face center Fc. 
     The deformation of the front part Fb 1  compensates the decrease in the rebound performance caused by the absence of the clearance g 1 . The rebound performance of a region in which the connecting part Cn 1  is present is increased by the deformation of the front part Fb 1 . 
     In respect of increasing the rebound performance, the thickness of the front part Fb 1  is preferably equal to or less than 5 mm, more preferably equal to or less than 4 mm, still more preferably equal to or less than 3 mm, yet still more preferably equal to or less than 2.8 mm, even yet still more preferably equal to or less than 2.6 mm, even yet still more preferably equal to or less than 2.4 mm, even yet still more preferably equal to or less than 2.2 mm, and even yet still more preferably equal to or less than 2 mm. In respect of a strength, the thickness of the front part Fb 1  is preferably equal to or greater than 1 mm, more preferably equal to or greater than 1.2 mm, still more preferably equal to or greater than 1.5 mm, yet still more preferably equal to or greater than 1.7 mm, and even yet still more preferably equal to or greater than 1.9 mm. 
     The front part Fb 1  includes a middle part in which an amount of displacement can be large. In respect of the rebound performance, the connecting part Cn 1  is preferably located in the middle part of the front part Fb 1 . In respect of increasing the displacement B, the connecting part Cn 1  is preferably located in the middle part. For example, in the planar view, the center of gravity of the connecting part Cn 1  is preferably located in the face middle region R 1 . In the planar view, the center of gravity of the connecting part Cn 1  is more preferably located in the middle inner side region R 3 . In light of the deformation of the front part Fb 1 , the whole connecting part Cn 1  is preferably included in the face middle region R 1  in the planar view. 
     [Fifth Embodiment] 
       FIG. 16  is an exploded perspective view of a head  50  according to a fifth embodiment. 
     The head  50  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The hosel  8  includes a hosel hole  10 . The inside of the head body h 1  is a space. The space is not closed. 
     In the head  50 , a peripheral edge f 21  of a face back surface f 2  is separated from the head body h 1 . The whole peripheral edge f 21  is separated from the head body h 1 . The peripheral edge f 21  is separated from a front part Fb 1 . A clearance is present between the peripheral edge f 21  and the head body h 1 . In the whole peripheral edge f 21 , the clearance is present between the peripheral edge f 21  and the head body h 1 . The clearance easily causes the displacement of the peripheral edge f 21 . A face surface f 1  is easily deformed in hitting. The deformation of the face part Fp 1  increases rebound performance. In the head  50 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     The connecting part Cn 1  of the head  50  is the same as the connecting part Cn 1  of the above-mentioned head  20 . The difference between the head  50  and the head  20  exists in the front part Fb 1 . In the head  20 , the front part Fb 1  blocks the whole front of a cavity part k 1 . Meanwhile, in the head  50 , the front part Fb 1  shields a part of a front of the cavity part k 1 . As shown in  FIG. 16 , an opening  52  is formed in the head body h 1 . A portion in which the front part Fb 1  is not present forms the opening  52 . The opening  52  is formed by the lack of the front part Fb 1 . In  FIG. 16 , under the presence of the opening  52 , the inside of the head body h 1  is viewable. 
     Thus, the front part Fb 1  of the head  50  is a partial front part Fb 2  shielding a part of a front of the cavity part of the head body h 1 . The partial front part Fb 2  connects an upper part (crown  4 ) of the head body h 1  and a lower part (sole  6 ) of the head body h 1  to each other. The partial front part Fb 2  is not connected to a toe portion of the head body h 1 . The partial front part Fb 2  is not connected to a heel portion of the head body h 1 . The cavity part k 1  is present behind the partial front part Fb 2 . The partial front part Fb 2  is easily deformed. In hitting, the amount of deformation of the partial front part Fb 2  is large. The partial front part Fb 2  contributes to an improvement in rebound performance. 
     The partial front part Fb 2  connects the crown  4  and the sole  6  to each other. The partial front part Fb 2  extends to the sole  6  from the crown  4 . The crown  4  is comparatively thin. For example, the thickness of the crown  4  is 0.5 mm or greater and 2.0 mm or less. The thin crown  4  is likely to be deformed. For this reason, the deformability of the partial front part Fb 2  is further increased. 
     The head  50  includes a first opening  52  provided on the toe side of the front part Fb 1  and a second opening  52  provided on the heel side of the front part Fb 1 . These openings  52  decrease the restraint to the front part Fb 1 . The front part Fb 1  is easily deformed. In the head  50 , a face middle region R 1  also has high rebound performance. 
     [Sixth to Twelfth Embodiments: Fairway Woods] 
       FIG. 17  is a front view of a head  60  according to a sixth embodiment. The head  60  is a fairway wood. 
     The head  60  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The hosel  8  includes a hosel hole. The head body h 1  includes a cavity part. The head  60  is a hollow head. The head body h 1  includes a front part disposed in front of the cavity part. 
     In the head  60 , a peripheral edge of a face back surface is separated from the head body h 1 . The whole peripheral edge of the face back surface is separated from the head body h 1 . The peripheral edge is separated from the front part. A clearance is present between the peripheral edge and the head body h 1 . The clearance can easily cause the displacement of the peripheral edge of the face back surface. A face surface f 1  is easily deformed in hitting. The deformation of the face part Fp 1  increases rebound performance. In the head  60 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     The connecting part Cn 1  is disposed substantially at the middle of the face part Fp 1 . In the planar view, the center of gravity of the connecting part Cn 1  is located in a face middle region R 1 . In the planar view, the center of gravity of the connecting part Cn 1  is located in a middle inner side region R 3 . In the planar view, the presence region of the connecting part Cn 1  includes a face center Fc. 
     As in the above-mentioned head  2 , the head  60  satisfies the following formula (1). In the head  60 , a peripheral edge part of the face surface f 1  has excellent rebound performance.
 
CT2&gt;CT1  (1)
 
     As in the above-mentioned head  2 , the head  60  satisfies the following relational formula (2). A sweet spot of the head  60  is large.
 
CT4&gt;CT3  (2)
 
     As in the above-mentioned head  2 , the head  60  satisfies the following relational formula (3). A sweet spot of the head  2  is large. In the head  60 , the peripheral edge part has excellent rebound performance.
 
CT5&gt;CT4  (3)
 
     As in the above-mentioned head  2 , the head  60  satisfies the following relational formula (4). In the head  60 , the peripheral edge part has excellent rebound performance.
 
CT6&gt;CT5  (4)
 
     A ball which is not teed up is often hit by the fairway wood. In the fairway wood, a ball is often hit on the lower side of the face surface f 1 . The clearance easily causes the displacement of the lower edge of the face surface f 1  in the head  60 . In the head  60 , the lower edge part of the face surface f 1  has high rebound performance. The structure of the head  60  is suitable for the fairway wood. The structure of the head  60  is suitable for a utility wood. The structure of the head  60  is suitable for a hybrid wood. 
       FIG. 18  is a front view of a head  70  according to a seventh embodiment. The head  70  is a fairway wood. 
     The head  70  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The hosel  8  includes a hosel hole. The head body h 1  includes a cavity part. The head  70  is a hollow head. The head body h 1  includes a front part disposed in front of the cavity part. 
     In the head  70 , a peripheral edge of a face back surface is separated from the head body h 1 . The whole peripheral edge of the face back surface is separated from the head body h 1 . The peripheral edge is separated from the front part. A clearance is present between the peripheral edge and the head body h 1 . The clearance can easily cause the displacement of the peripheral edge of the face back surface. The clearance easily causes the deformation of a face surface f 1  in hitting. 
     The connecting part Cn 1  is disposed on the upper side of the face part Fp 1 . In the planar view, the whole connecting part Cn 1  is included in the upper side region. In the planar view, the presence region of the connecting part Cn 1  does not include a face center Fc. 
     As in the above-mentioned head  30 , in the head  70 , a lower edge part of the face surface f 1  can be largely displaced. In the head  70 , the lower edge part of the face surface f 1  has particularly high rebound performance. The structure of the head  70  is particularly suitable for the fairway wood. Similarly, the structure of the head  70  is suitable also for a utility wood and a hybrid wood. 
       FIG. 19  is a front view of a head  80  according to an eighth embodiment. The head  80  is a fairway wood. 
     The head  80  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The hosel  8  includes a hosel hole. The head body h 1  includes a cavity part. The head  80  is a hollow head. The head body h 1  includes a front part disposed in front of the cavity part. 
     In the head  80 , a peripheral edge of a face back surface is separated from the head body h 1 . The whole peripheral edge of the face back surface is separated from the head body h 1 . The peripheral edge is separated from the front part. A clearance is present between the peripheral edge and the head body h 1 . The clearance can easily cause the displacement of the peripheral edge of the face back surface. The clearance easily causes the deformation of a face surface f 1  in hitting. A peripheral edge part of the face part Fp 1  has a high degree of freedom of deformation. In the head  80 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     The connecting part Cn 1  is disposed on the upper side of the face part Fp 1 . In the planar view, the whole connecting part Cn 1  is included in the upper side region. In the planar view, the presence region of the connecting part Cn 1  does not include a face center Fc. 
     As in the above-mentioned head  30 , in the head  80 , a lower edge part of the face surface f 1  can be largely displaced. In the head  80 , the lower edge part of the face surface f 1  has particularly high rebound performance. The structure of the head  80  is particularly suitable for the fairway wood. Similarly, the structure of the head  80  is suitable also for a utility wood and a hybrid wood. 
     In the head  80 , the connecting part Cn 1  extends in a curved state. In the planar view, the curve is convexed to the upper side. A distance in an up-down direction between the lower edge of the face back surface and the connecting part Cn 1  is shown by a double-headed arrow D 1  in  FIG. 19 . The curve can cause an increase in the distance D 1  in a middle part of the face surface f 1 . Therefore, the rebound performance of the middle part of the face surface f 1  can be improved. 
       FIG. 20  is a front view of a head  90  according to a ninth embodiment. The head  90  is a fairway wood. 
     The head  90  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . A plurality of connecting parts Cn 1  are provided. The two connecting parts Cn 1  connect the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only these connecting parts Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The hosel  8  includes a hosel hole. The head body h 1  includes a cavity part. The head  90  is a hollow head. The head body h 1  includes a front part disposed in front of the cavity part. 
     In the head  90 , a peripheral edge of a face back surface is separated from the head body h 1 . The whole peripheral edge of the face back surface is separated from the head body h 1 . The peripheral edge is separated from the front part. A clearance is present between the peripheral edge and the head body h 1 . The clearance can easily cause the displacement of the peripheral edge of the face back surface. The clearance easily causes the deformation of a face surface f 1  in hitting. A peripheral edge part of the face part Fp 1  has a high degree of freedom of deformation. 
     A first connecting part Cn 1  is disposed in a toe region. A second connecting part Cn 1  is disposed in a heel region. The plurality of connecting parts Cn 1  can stably support the face part Fp 1 . If the number of the connecting parts Cn 1  is plural, the size of each connecting part Cn 1  can be reduced. Therefore, a nonbackup region N 1  (described below) can be increased. Furthermore, if the number of the connecting parts Cn 1  is plural, the degree of freedom of disposal of the connecting parts Cn 1  is increased. Therefore, the durability of the head can be increased while a backup region B 1  (described below) is suppressed. 
       FIG. 21  is a front view of a head  100  according to a tenth embodiment. The head  100  is a fairway wood. 
     The head  100  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The hosel  8  includes a hosel hole. The head body h 1  includes a cavity part. The head  100  is a hollow head. The head body h 1  includes a front part disposed in front of the cavity part. 
     In the head  100 , a peripheral edge of a face back surface is separated from the head body h 1 . The whole peripheral edge of the face back surface is separated from the head body h 1 . The peripheral edge is separated from the front part. A clearance is present between the peripheral edge and the head body h 1 . The clearance can easily cause the displacement of the peripheral edge of the face back surface. A face surface f 1  is easily deformed in hitting. A peripheral edge part of the face part Fp 1  has a high degree of freedom of deformation. In the head  100 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     In the planar view, the connecting part Cn 1  has an elliptical shape. In the planar view, the border line of the connecting part Cn 1  is constituted by only a curve. The border constituted by the curve can mitigate stress concentration in the border. The mitigation can contribute to an improvement in durability. The size of the connecting part Cn 1  in a toe-heel direction is greater than the size of the connecting part Cn 1  in an up-down direction. Therefore, the face surface f 1  can be stably supported. 
       FIG. 22  is a front view of a head  110  according to an eleventh embodiment. The head  110  is a fairway wood. 
     The head  110  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The hosel  8  includes a hosel hole. The head body h 1  includes a cavity part. The head  110  is a hollow head. The head body h 1  includes a front part disposed in front of the cavity part. 
     In the head  110 , a peripheral edge of a face back surface is separated from the head body h 1 . The whole peripheral edge of the face back surface is separated from the head body h 1 . The peripheral edge is separated from the front part. A clearance is present between the peripheral edge and the head body h 1 . The clearance can easily cause the displacement of the peripheral edge of the face back surface. A face surface f 1  is easily deformed in hitting. A peripheral edge part of the face part Fp 1  has a high degree of freedom of deformation. In the head  110 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     In the planar view, the connecting part Cn 1  has an X character shape. The connecting part Cn 1  includes a first extending part Cn 11  inclined so that it go to an upper side toward a toe side, and a second extending part Cn 12  inclined so that it go to an upper side toward a heel side. The first extending part Cn 11  and the second extending part Cn 12  cross each other. The connecting part Cn 1  can stably support the face part Fp 1 . The connecting part Cn 1  has an excellent balance between a large high restitution region and high durability. 
       FIG. 23  is a front view of a head  120  according to a twelfth embodiment. The head  120  is a fairway wood. 
     The head  120  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . A plurality of connecting parts Cn 1  are provided. The two connecting parts Cn 1  connect the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only these connecting parts Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The hosel  8  includes a hosel hole. The head body h 1  includes a cavity part. The head  120  is a hollow head. The head body h 1  includes a front part disposed in front of the cavity part. 
     In the head  120 , a peripheral edge of a face back surface is separated from the head body h 1 . The whole peripheral edge of the face back surface is separated from the head body h 1 . The peripheral edge is separated from the front part. A clearance is present between the peripheral edge and the head body h 1 . The clearance can easily cause the displacement of the peripheral edge of the face back surface. A face surface f 1  is easily deformed in hitting. A peripheral edge part of the face part Fp 1  has a high degree of freedom of deformation. In the head  120 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     A first connecting part Cn 11  is disposed in a toe region. A second connecting part Cn 12  is disposed in a heel region. The plurality of connecting parts Cn 1  can stably support the face part Fp 1 . If the number of the connecting parts all is plural, the size of each connecting part Cn 1  can be reduced. Therefore, the region in which the clearance is present can be increased. Furthermore, if the number of the connecting parts ail is plural, the degree of freedom of disposal of the connecting parts Cn 1  is increased. Therefore, both a large high restitution region and high durability can be achieved. 
     In the planar view, the first connecting part Cn 11  is curved. The curve is convexed to a toe side. The second connecting part Cn 12  is curved in the planar view. The curve is convexed to a heel side. A distance in a toe-heel direction between the first connecting part Cn 11  and the second connecting part Cn 12  is shown by a double-headed arrow D 2  in  FIG. 23 . The curve can cause an increase in the distance D 2  in a middle part of the face surface f 1 . Therefore, the rebound performance of the middle part of the face surface f 1  can be improved. 
     [Thirteenth and Fourteenth Embodiments: Irons] 
       FIG. 24  is a front view of a head  130  according to a thirteenth embodiment. The head  130  is an iron head.  FIG. 25  is an exploded perspective view of the head  130 .  FIG. 26  is a cross-sectional view taken along line F 26 -F 26  of  FIG. 24 . 
     The head  130  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . 
     The head body h 1  includes a top part  11 , a sole  12 , and a hosel  14 . The hosel  14  includes a hosel hole  16 . 
     The head  130  is a so-called cavity back iron. As shown in  FIG. 26 , the head body h 1  includes a cavity part k 1 . The cavity part k 1  is a recess part. The cavity part k 1  in the present embodiment is a cavity part of the cavity back iron. 
     The head body h 1  includes a front part Fb 1  (see  FIGS. 25 and 26 ). The front part Fb 1  is disposed in front of the cavity part k 1 . The front part Fb 1  shields at least a part of a front of the cavity part k 1 . The front part Fb 1  connects an upper part of the head body h 1 , and a lower part of the head body h 1  to each other. In the present embodiment, the upper part of the head body h 1  is the top part  11 . In the embodiment, the lower part of the head body h 1  is the sole  12 . As shown in  FIG. 25 , in the head  130 , the front part Fb 1  covers the whole front of the cavity part k 1 . The front part Fb 1  is located behind the face part Fp 1 . The front part Fb 1  forms a bottom surface of the cavity part. 
     The connecting part Cn 1  is integrally molded with the face part Fp 1 . The connecting part Cn 1  is joined to the head body h 1  (front part Fb 1 ). The joining is welding. 
     The front part Fb 1  includes a front surface b 1  and a back surface b 2 . The front surface b 1  is a plane. The back surface b 2  is a plane. The back surface b 2  faces the cavity part k 1 . The back surface b 2  forms the bottom surface of the cavity part. The connecting part Cn 1  connects the front surface b 1  and the face part Fp 1  to each other. 
     The face part Fp 1  includes a face surface f 1  and a face back surface f 2 . The face surface f 1  is a hitting surface. The face back surface f 2  is opposed to the front surface b 1 . A plurality of score line grooves  18  are formed in the face surface f 1 . Except for the score line grooves  18 , the face surface f 1  is a plane. The face back surface f 2  is a plane. The score line grooves  18  are abbreviated in the cross-sectional view of  FIG. 26 . 
     The face part Fp 1  is plate-like as a whole. A clearance g 1  is provided between the face part Fp 1  and the front part Fb 1  (see  FIG. 26 ). 
     The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The head body h 1  and the face part Fp 1  are connected to each other by only the connecting part Cn 1 . The connecting part Cn 1  connects the face back surface f 2  and the front surface b 1  to each other. Except for a portion at which the connecting part Cn 1  is present, the clearance g 1  is present between the face back surface f 2  and the front surface b 1 . 
     As shown in  FIG. 26 , the connecting part Cn 1  is solid. The connecting part Cn 1  may be hollow. 
     As described above, the face part Fp 1  includes the face surface f 1  and the face back surface f 2 . The face back surface f 2  includes a peripheral edge f 21 . The connecting part Cn 1  is provided at a position separated from the peripheral edge f 21 . 
     As shown in  FIG. 24 , the shape of the connecting part Cn 1  in the planar view is a rectangle. In more detail, the shape of the connecting part Cn 1  in the planar view is a square. 
     In the head  130 , the whole peripheral edge f 21  is separated from the connecting part Cn 1 . A part of the peripheral edge f 21  may be separated from the connecting part Cn 1 . In other words, the connecting part Cn 1  may be connected to a part of the peripheral edge f 21 . 
     The connecting part Cn 1  is located on a face center Fc side with respect to the peripheral edge f 21 . In the planar view, the center of gravity of the connecting part Cn 1  is located in a face middle region R 1 . In the planar view, the whole connecting part Cn 1  is included in the face middle region R 1 . A backup region B 1  (described below) includes a face center Fc. 
     As described above, the front part Fb 1  of the head body h 1  includes the front surface b 1 . The front surface b 1  includes a peripheral edge b 11 . 
     In the head  130 , the peripheral edge b 11  is separated from the connecting part Cn 1 . The whole peripheral edge b 11  is separated from the connecting part Cn 1 . A part of the peripheral edge b 11  may be separated from the connecting part Cn 1 . In other words, the connecting part Cn 1  may be disposed on a part of the peripheral edge b 11 . 
     The peripheral edge f 21  is separated from the head body h 1 . The whole peripheral edge f 21  is separated from the head body h 1 . The peripheral edge f 21  is separated from the front part Fb 1 . The clearance g 1  is present between the peripheral edge f 21  and the head body h 1 . In the whole peripheral edge f 21 , the clearance g 1  is present between the peripheral edge f 21  and the head body h 1 . The peripheral edge f 21  is easily displaced. The clearance g 1  easily causes the deformation of the face surface f 1  in hitting. A peripheral edge part of the face part Fp 1  has a high degree of freedom of deformation. The deformation of the face part Fp 1  increases rebound performance. In the head  130 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     In the head  130 , the connecting part Cn 1  is provided only in the face middle region R 1 . The connecting part Cn 1  is not present in a face peripheral region R 2 . The whole face peripheral region R 2  is not backed up. The face peripheral region R 2  does not include the backup region B 1 . The whole face peripheral region R 2  is a nonbackup region N 1 . The whole backup region B 1  is included in the face middle region R 1 . In the whole face peripheral region R 2 , the clearance g 1  is present on the back side of the face part Fp 1 . The face peripheral region R 2  has high deformability. The face peripheral region R 2  has high rebound performance. The backup region B 1  and the nonbackup region N 1  will be described below in detail. 
       FIG. 27  is an exploded perspective view of a head  140  according to a fourteenth embodiment. 
     The head  140  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only the connecting part Cn 1 . 
     The head body h 1  includes a sole  12  and a hosel  14 . The hosel  14  includes a hosel hole  16 . 
     The head  140  is a so-called cavity back iron. The head body h 1  includes a cavity part k 1  on a back side. The cavity part k 1  is a recess part. The cavity part k 1  in the present embodiment is a cavity part of the cavity back iron. 
     The head body h 1  includes a front part Fb 1 . The front part Fb 1  is located in front of the cavity part k 1 . The front part Fb 1  shields a part of a front of the cavity part k 1 . 
     The connecting part Cn 1  is integrally molded with the face part Fp 1 . The connecting part Cn 1  is joined to the head body h 1  (front part Fb 1 ). The joining is welding. 
     The front part Fb 1  includes a front surface b 1  and a back surface b 2 . The front surface b 1  is a plane. The back surface b 2  is a plane. The back surface b 2  faces the cavity part k 1 . The back surface b 2  forms a bottom surface of the cavity part. The connecting part Cn 1  connects the front surface b 1  and the face part Fp 1  to each other. 
     The face part Fp 1  includes a face surface f 1  and a face back surface. The face surface f 1  is a hitting surface. The face back surface is opposed to the front surface b 1 . A plurality of score line grooves  18  are formed in the face surface f 1 . Except for the score line grooves  18 , the face surface f 1  is a plane. The face back surface is a plane. 
     The face part Fp 1  is plate-like as a whole. A clearance is provided between the face part Fp 1  and the front part Fb 1 . 
     The connecting part Cn 1  connects the head body h 1  and the face part Fp 1  to each other. The head body h 1  and the face part Fp 1  are connected to each other by only the connecting part Cn 1 . The connecting part Cn 1  connects the face back surface and the front surface b 1  to each other. Except for a portion at which the connecting part Cn 1  is present, a clearance is present between the face back surface f 2  and the front surface b 1 . 
     The face back surface includes a peripheral edge f 21 . The connecting part Cn 1  is provided at a position separated from the peripheral edge f 21 . In the head  140 , the whole peripheral edge f 21  is separated from the connecting part Cn 1 . A part of the peripheral edge f 21  may be separated from the connecting part Cn 1 . In other words, the connecting part Cn 1  may be connected to a part of the peripheral edge f 21 . 
     The connecting part Cn 1  is located on a face center Fc side with respect to the peripheral edge f 21 . In the planar view, the center of gravity of the connecting part Cn 1  is located in a face middle region R 1 . In the planar view, the whole connecting part Cn 1  is included in the face middle region R 1 . A backup region B 1  (described below) includes a face center Fc. 
     The front part Fb 1  of the head body h 1  includes the front surface b 1 . The front surface b 1  has a peripheral edge b 11 . 
     The peripheral edge b 11  is separated from the connecting part Cn 1 . The whole peripheral edge b 11  is separated from the connecting part Cn 1 . A part of the peripheral edge b 11  may be separated from the connecting part Cn 1 . In other words, the connecting part Cn 1  may be disposed on a part of the peripheral edge b 11 . 
     The peripheral edge f 21  is separated from the head body h 1 . The whole peripheral edge f 21  is separated from the head body h 1 . The peripheral edge f 21  is separated from the front part Fb 1 . A clearance is present between the peripheral edge f 21  and the head body h 1 . In the whole peripheral edge f 21 , the clearance is present between the peripheral edge f 21  and the head body h 1 . The clearance easily causes the displacement of the peripheral edge f 21 . A face surface f 1  is easily deformed in hitting. A peripheral edge part of the face part Fp 1  has a high degree of freedom of deformation. The deformation of the face part Fp 1  increases rebound performance. In the head  140 , a peripheral edge part of the face surface f 1  has excellent rebound performance. 
     The connecting part Cn 1  of the head  140  is the same as the connecting part Cn 1  of the above-mentioned head  130 . The difference between the head  140  and the head  130  exists in the front part Fb 1 . In the head  130 , the front part Fb 1  blocks the whole front of the cavity part k 1  of the head body h 1 . Meanwhile, in the head  140 , the front part Fb 1  shields a part of a front of the cavity part k 1  of the head body h 1 . As shown in  FIG. 27 , an opening  142  is formed in the head body h 1 . A portion at which the front part Fb 1  is not present forms the opening  142 . The opening  142  is formed by the lack of the front part Fb 1 . In  FIG. 27 , under the presence of the opening  142 , the cavity part of the head body h 1  is viewable. 
     Thus, the front part Fb 1  of the head  140  is a partial front part Fb 2  blocking a part of the front of the cavity part k 1  of the head body h 1 . The opening  142  is formed so as to be adjacent to the partial front part Fb 2 . A first opening  142  is formed on the toe side of the partial front part Fb 2 . A second opening  142  is formed on the heel side of the partial front part Fb 2 . The partial front part Fb 2  is likely to be deformed. In hitting, the amount of deformation of the partial front part Fb 2  is large. The partial front part Fb 2  contributes to an improvement in rebound performance. 
     The head  140  includes the first opening  142  provided on the toe side of the front part Fb 1  and the second opening  142  provided on the heel side of the front part Fb 1 . Therefore, the front part Fb 1  is easily deformed. Large deformation is generated in a middle part of the front part Fb 1 . In the head  140 , the face middle region R 1  has high rebound performance. 
       FIG. 28  is a cross-sectional view of a head  150  according to a fifteenth embodiment. The head  150  includes an interposition member  152 . The clearance g 1  is filled with the interposition member  152 . The interposition member  152  is disposed between a face part Fp 1  and a front part Fb 1 . A space located between the face part Fp 1  and the front part Fb 1  is partially filled with the interposition member  152 . The space located between the face part Fp 1  and the front part Fb 1  may be wholly filled with the interposition member  152 . The interposition member  152  can prevent the intrusion of a foreign substance into the clearance g 1 . The interposition member  152  can increase appearance properties or designability. The head  150  is the same as the above-mentioned head  2  except for presence of the interposition member  152 . 
     In respect of rebound performance, it is preferable that the interposition member  152  does not inhibit the deformation of the face part Fp 1 . In respect of the rebound performance, the interposition member  152  is preferably flexible. In this respect, the material of the interposition member  152  is preferably a polymer. Examples of the polymer include a rubber and a resin. The resin is preferably a synthetic resin. In respect of the rebound performance, the Young&#39;s modulus of the interposition member  152  is preferably equal to or less than 1 GPa, more preferably equal to or less than 500 MPa, and still more preferably equal to or less than 100 MPa. In respect of preventing disengagement, the Young&#39;s modulus of the interposition member  152  is preferably equal to or greater than 0.1 MPa. 
     Thus, in respect of the rebound performance, it is preferable that a space is provided behind a peripheral edge f 20  of the face part Fp 1 , or the interposition member is disposed behind a peripheral edge f 20  of the face part Fp 1 . 
       FIG. 29  is a cross-sectional view of a head  160  according to a sixteenth embodiment. The head  160  is a fairway wood. 
     The head  160  includes a head body h 1 , a face part Fp 1 , and a connecting part Cn 1 . A plurality of (two) connecting parts Cn 1  are provided. The two connecting parts Cn 1  connect the head body h 1  and the face part Fp 1  to each other. The face part Fp 1  is connected to the head body h 1  by only these connecting parts Cn 1 . The head body h 1  includes a crown  4 , a sole  6 , and a hosel  8 . The hosel  8  includes a hosel hole. The head body h 1  includes a cavity part. The head  160  is a hollow head. The head body h 1  includes a front part disposed in front of the cavity part. 
     A first connecting part Cn 11  is disposed on a toe region. A second connecting part Cn 12  is disposed on a heel region. The plurality of (two) connecting parts Cn 1  stably support the face part Fp 1 . 
     The difference between the head  160  and the above-mentioned head  120  is only the connecting part Cn 1 . As compared with the head  120 , in the head  160 , the first connecting part Cn 11  is located on a further toe side, and the second connecting part Cn 12  is located on a further heel side. 
     A clearance between the face part Fp 1  and the head body h 1  penetrates from the crown  4  to the sole  6  between the connecting part Cn 11  and the connecting part Cn 12 . The clearance between the face part Fp 1  and the head body h 1  penetrates the head  160  in an up-down direction. The face part Fp 1  has a high degree of freedom of deformation between the connecting part Cn 11  and the connecting part Cn 12 . 
     The first connecting part Cn 11  is disposed on the most toe side. For this reason, an outer edge E 1  of the connecting part Cn 11  includes a common part E 21  shared with a peripheral edge f 21  of a face back surface f 2 . The second connecting part Cn 12  is disposed on the most heel side. For this reason, an outer edge E 2  of the connecting part Cn 12  includes the common part E 21 . In the head  160 , a distance in a toe-heel direction between the first connecting part Cn 11  and the second connecting part Cn 12  is large. For this reason, a face region which is not backed up by the connecting part Cn 1  is broadened. The face region is likely to be deformed by hitting, and has excellent rebound performance. 
     In the head  160 , the connecting part Cn 1  is not provided at a position separated from the peripheral edge of the face back surface. However, in the head  160 , the peripheral edge of the face back surface is separated from the head body h 1 . That is, in a nonbackup region N 1 , the peripheral edge of the face back surface is separated from the head body h 1 . Therefore, the rebound performance of a middle part of a face surface f 1  in the toe-heel direction is high. In the middle part in the toe-heel direction, all of the upper part, the middle part, and the lower part of the face surface f 1  are the nonbackup region N 1 . Therefore, all of the upper part, the middle part, and the lower part have high rebound performance. 
     A backup region B 1  and a nonbackup region N 1  are shown with the head  160  as an example in  FIG. 30 . A region backed up by the connecting part Cn 1  in the face surface f 1  is the backup region B 1 . A region which is not backed up by the connecting part Cn 1  in the face surface f 1  is the nonbackup region N 1 . The backup region B 1  and the nonbackup region N 1  are estimated in the planar view. In  FIG. 30 , the backup region B 1  is shown by dashed line hatching, and the nonbackup region N 1  is shown by solid line hatching. In the nonbackup region N 1 , a space (clearance g 1 ) is present on the back side of the face part Fp 1 . In the nonbackup region N 1 , an interposition member  152  may be present on the back side of the face part Fp 1  (see  FIG. 28 ). 
     The area of the backup region B 1  is defined as Sb. The area of the nonbackup region N 1  is defined as Sn. In the embodiment of  FIG. 30 , the total of the areas of the two backup regions B 1  is Sb. In respect of the rebound performance, a ratio [Sb/Sn] is preferably equal to or less than 0.5, more preferably equal to or less than 0.4, still more preferably equal to or less than 0.3, and yet still more preferably equal to or less than 0.25. In respect of a strength, the ratio [Sb/Sn] is preferably equal to or greater than 0.05, and more preferably equal to or greater than 0.1. 
     In respect of the rebound performance, a CT value in a face center Fc is preferably equal to or greater than 160 μs, more preferably equal to or greater than 170 μs, still more preferably equal to or greater than 180 μs, and yet still more preferably equal to or greater than 190 μs. In respect of the golf rule, the CT value in the face center Fc is preferably equal to or less than 257 μs. 
     Usually, the face area of the fairway wood is smaller than the face area of a driver. For this reason, in the fairway wood, the deformation of the face in hitting may not be sufficiently obtained. This point is the same also in a utility type club, a hybrid type club, and an iron type club. By the above-mentioned technique, the rebound performance can be improved also in a head having a small face area. In this respect, a head volume is preferably equal to or less than 300 cc, more preferably less than 300 cc, still more preferably equal to or less than 280 cc, and yet still more preferably equal to or less than 260 cc. In the wood type club, the utility type club, and the hybrid type club (including a hollow iron), the rebound performance and the flight distance are considered to be particularly important. If the point is also considered, the head volume is preferably equal to or greater than 100 cc. 
     In respect of the rebound performance, the thickness of the face part Fp 1  is preferably equal to or less than 5 mm, and more preferably equal to or less than 4 mm. In respect of the strength, the thickness of the face part Fp 1  is preferably equal to or greater than 1.0 mm, more preferably equal to or greater than 1.5 mm, still more preferably equal to or greater than 1.8 mm, and yet still more preferably equal to or greater than 2 mm. The thickness of the face part Fp 1  may be uniform or non-uniform. In Examples to be described below, the thickness of the face part Fp 1  is non-uniform. In Examples, the thickness of the face part Fp 1  near the middle of the face part Fp 1  is 4 mm, and the thickness of the face part Fp 1  in the peripheral edge is 2 mm. 
     A distance between the face back surface f 2  and the front surface b 1  is shown by a double-headed arrow v 1  in  FIG. 4 . In respect of allowing the deformation of the face part Fp 1 , the distance v 1  is preferably equal to or greater than 0.2 mm, more preferably equal to or greater than 0.5 mm, and still more preferably equal to or greater than 1.0 mm. In respect of good appearance, and in respect of suppressing the intrusion of a foreign substance, the distance v 1  is preferably equal to or less than 20 mm, more preferably equal to or less than 10 mm, and still more preferably equal to or less than 8 mm. The distance v 1  is measured along a face-back direction. The distance v 1  may be uniform or non-uniform. 
     The material of the head body h 1  is not limited. Examples of the material of the head body h 1  include a metal and CFRP (carbon fiber reinforced plastic). Examples of the metal include one or more kinds selected from soft iron, pure titanium, a titanium alloy, stainless steel, maraging steel, an aluminium alloy, a magnesium alloy, and a tungsten-nickel alloy. Examples of the stainless steel include SUS630 and SUS304. Specific examples of the titanium alloy include 6-4 titanium (Ti-6Al-4V), Ti-15V-3Cr-3Sn-3Al, and Ti-6-22-22S. The soft iron means low carbon steel having a carbon content of less than 0.3 wt %. The material of the head body h 1  can be preferably welded to the connecting part Cn 1 . The material of the head body h 1  may be the same as the material of the connecting part Cn 1 . 
     The material of the face part Fp 1  is not limited. Examples of the material of the face part Fp 1  include a metal and CFRP (carbon fiber reinforced plastic) or the like. Examples of the metal include one or more kinds selected from soft iron, pure titanium, a titanium alloy, stainless steel, maraging steel, an aluminium alloy, a magnesium alloy, and a tungsten-nickel alloy. Examples of the stainless steel include SUS630 and SUS304. Specific examples of the titanium alloy include 6-4 titanium (Ti-6Al-4V), Ti-15V-3Cr-3Sn-3Al, and Ti-6-22-22S or the like. The material of the face part Fp 1  can be preferably welded to the connecting part Cn 1 . The material of the face part Fp 1  may be the same as the material of the connecting part Cn 1 . 
     The face part Fp 1  may be made of a rolled material. The rolled material has few defects, and has an excellent strength. The face part Fp 1  may be made of a forging material. The forging material has few defects, and has an excellent strength. The face part Fp 1  having an excellent strength can exhibit high durability while allowing large deformation. 
     As described above, the face surface f 1  is a three-dimensional curved surface having the bulge and the roll. In respect of applying the bulge and the roll, the face part Fp 1  may be formed by bending work. 
     A preferable example of the head is a driver head. The driver means a number  1  wood (W# 1 ). High flight distance performance is required for the driver. Therefore, the present invention is preferably applied. Usually, the driver head has the following constitution. 
     (1a) curved face surface 
     (1b) cavity part 
     (1c) volume of 300 cc or greater and 460 cc or less 
     (1d) real loft of 7 degrees or greater and 14 degrees or less 
     Another preferable example of the head is a fairway wood head. Examples of the fairway wood include a number  3  wood (W# 3 ), a number  4  wood (W# 4 ), a number  5  wood (W# 5 ), a number  7  wood (W# 7 ), a number  9  wood (W# 9 ), a number  11  wood (W# 11 ), and a number  13  wood (W# 13 ). Usually, the fairway wood head has the following constitution. 
     (2a) curved face surface 
     (2b) cavity part 
     (2c) volume of 100 cc or greater and less than 300 cc 
     (2d) real loft of greater than 14 degrees and 33 degrees or less 
     More preferably, the volume of the fairway wood head is 100 cc or greater and 200 cc or less. 
     The head of the fairway wood is smaller than the head of the driver. A smaller head includes a face surface having a smaller area. The conventional structure makes it difficult to increase the rebound performance of the smaller face surface. The above-mentioned structure is effective for increasing the rebound performance of the smaller face surface. 
     A ball placed on a ground (lawn) is often hit by the fairway wood. In other words, a ball which is not teed up is often hit by the fairway wood. Therefore, in the fairway wood, a hit point tends to be located on the lower side of the face surface. In the conventional structure, the deflection of a lower edge part of a face surface is small. The conventional structure makes it difficult to increase the rebound performance of the lower edge part of the face surface. The above-mentioned structure can solve the problem. 
     Still another preferable example of the head is a utility type head (hybrid type head). Usually, the utility type head (hybrid type head) has the following constitution. 
     (3a) curved face surface 
     (3b) cavity part 
     (3c) volume of 100 cc or greater and 200 cc or less 
     (3d) real loft of 15 degrees or greater and 33 degrees or less 
     More preferably, the volume of the utility type head (hybrid type head) is 100 cc or greater and 150 cc or less. 
     The head of the utility type club (hybrid type club) is smaller than the head of the driver. In the conventional structure, the amount of deflection of the smaller face surface is smaller. The above-mentioned structure is effective for increasing the rebound performance of the smaller face surface. 
     A ball placed on a ground (lawn) is often hit by the utility club (hybrid club). In other words, a ball which is not teed up is often hit by the utility club (hybrid club). Therefore, in the utility club (hybrid club), a hit point tends to be located on the lower side of the face surface. In the conventional structure, the deflection of a lower edge part of a face surface is smaller. The conventional structure makes it difficult to increase the rebound performance of the lower edge part of the face surface. In the above-mentioned head, the deflection of the lower edge part of the face surface is large. The above-mentioned structure can increase the rebound performance of the lower edge part of the face surface. 
     EXAMPLES 
     Hereinafter, the effects of the present invention will be clarified by Examples. However, the present invention should not be interpreted in a limited way based on the description of Examples. 
     Comparative Example 
     A number  3  wood of XXIO PRIME manufactured by Dunlop Sports Co., Ltd. (launched on 2013) was used as a reference head. Three-dimensional data of the reference head was subjected to element breakdown to obtain head data of Comparative Example. The physical properties of each portion of the head were set so as to close as possible to an actual head. The specifications of Comparative Example are shown in the following Table 1. 
     Example 1 
     A face part of the head data of Comparative Example was removed to form an opening, and a plate-like front part was provided so as to block the opening. Furthermore, a connecting part Cn 1  and a face part Fp 1  were provided on a front surface b 1  of the front part, to obtain head data of Example 1. The structure of Example 1 is the same as the structure of the above-mentioned head  60 . 
       FIGS. 31 to 35  show an image of an FE model (finite element model) of a head  170  according to Example 1.  FIG. 31  is a perspective view of the head  170 .  FIG. 32  is a perspective view of a face part Fp 1  of the head  170  viewed from a back side.  FIG. 33  is a perspective view of a head body h 1  of the head  170 .  FIG. 34  is a top view of the head  170 .  FIG. 35  is a cross-sectional view taken along line F 35 -F 35  of  FIG. 34 . Hatching showing a section is abbreviated in the cross-sectional view. 
     As a result of performing simulation for making a ball collide with Example 1, the displacement of a peripheral edge part of the face part Fp 1  was confirmed to be greater than the displacement of Comparative Example. 
     Example 2 
     Head data of Example 2 was obtained in the same manner as in Example 1 except that a toe part and a heel part of a front part were removed, and a connecting part Cn 1  had a rectangle shape which was longer in a toe-heel direction. The structure of Example 2 is the same as the structure of the above-mentioned head  50 . 
       FIGS. 36 and 37  show an image of an FE model of a head  180  according to Example 2.  FIG. 36  is a perspective view of the head  180 .  FIG. 37  is a perspective view of a head body h 1  of the head  180 . As a result of performing simulation for making a ball collide with Example 2, an upper edge part and a lower edge part of a face part Fp 1  were confirmed to be displaced more largely than the upper edge part and the lower edge part of the face part Fp 1  of Example 1. The large displacement was caused by the deformation of a front part Fb 1  (partial front part Fb 2 ). 
     Example 3 
     Head data of Example 3 was obtained in the same manner as in Example 1 except that a connecting part Cn 1  had a rectangle shape which was longer in a toe-heel direction, and was moved to an upper side. The structure of Example 3 is the same as the structure of the above-mentioned head  70 . 
       FIGS. 38 to 42  show an image of an FE model of a head  190  according to Example 3.  FIG. 38  is a perspective view of the head  190 .  FIG. 39  is a perspective view of a face part Fp 1  of the head  190  viewed from a back side.  FIG. 40  is a perspective view of a head body h 1  of the head  190 .  FIG. 41  is a top view of the head  190 .  FIG. 42  is a cross-sectional view taken along line F 42 -F 42  of  FIG. 41 . Hatching is not applied to the cross-sectional view. 
     The specifications of Example 3 and Comparative Example are shown in the following Table 1. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Specifications of Example and Comparative Example 
               
            
           
           
               
               
               
               
            
               
                   
                   
                 Comparative 
                   
               
               
                   
                 Unit 
                 Example 
                 Example 3 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                 Face part 
                 Assumed material 
                 — 
                 6-22-22S 
                 6-22-22S 
               
               
                   
                   
                   
                 titanium 
                 titanium 
               
               
                   
                 Elastic modulus 
                 GPa 
                 120 
                 120 
               
               
                   
                 Density 
                 g/cm 3   
                 4.6 
                 2.0 
               
               
                   
                 Weight 
                 g 
                 30.6 
                 15.3 
               
               
                 Head body 
                 Assumed material 
                 — 
                 Maraging 
                 Maraging 
               
               
                 (excluding 
                   
                   
                 steel 
                 steel 
               
               
                 sole and 
                 Elastic modulus 
                 GPa 
                 210 
                 210 
               
               
                 front part) 
                 Density 
                 g/cm 3   
                 7.8 
                 7.8 
               
               
                   
                 Weight 
                 g 
                 119.7 
                 119.7 
               
               
                 Sole 
                 Assumed material 
                 — 
                 W—Ni alloy 
                 W—Ni alloy 
               
               
                   
                 Elastic modulus 
                 GPa 
                 530 
                 530 
               
               
                   
                 Density 
                 g/cm 3   
                 8.3 
                 8.3 
               
               
                   
                 Weight 
                 g 
                 40.4 
                 40.4 
               
               
                 Front part 
                 Assumed material 
                 — 
                 — 
                 6-22-22S 
               
               
                   
                   
                   
                   
                 titanium 
               
               
                   
                 Elastic modulus 
                 GPa 
                 — 
                 120 
               
               
                   
                 Density 
                 g/cm 3   
                 — 
                 2.0 
               
               
                   
                 Weight 
                 g 
                 — 
                 10.3 
               
               
                 Connecting 
                 Assumed material 
                 — 
                 — 
                 6-22-22S 
               
               
                 part 
                   
                   
                   
                 titanium 
               
               
                   
                 Elastic modulus 
                 GPa 
                 — 
                 120 
               
               
                   
                 Density 
                 g/cm 3   
                 — 
                 2.0 
               
               
                   
                 Weight 
                 g 
                 — 
                 5.0 
               
            
           
           
               
               
               
               
            
               
                 Total number of elements of 
                 Piece 
                 45008 
                 54135 
               
               
                 head 
               
               
                 Head weight 
                 g 
                 190.7 
                 190.7 
               
               
                 X-coordinate of sweet spot 
                 mm 
                 2.0 
                 1.8 
               
               
                 Y-coordinate of sweet spot 
                 mm 
                 6.3 
                 6.7 
               
               
                 X-coordinate of center of 
                 mm 
                 27.6 
                 27.8 
               
               
                 gravity of head 
               
               
                 Y-coordinate of center of 
                 mm 
                 −1.9 
                 −1.7 
               
               
                 gravity of head 
               
               
                 Z-coordinate of center of 
                 mm 
                 16.2 
                 16.1 
               
               
                 gravity of head 
               
               
                 Head inertia moment A 
                 g · cm 2   
                 2712 
                 2669 
               
               
                 Head inertia moment B 
                 g · cm 2   
                 1157 
                 1128 
               
               
                   
               
            
           
         
       
     
     Coordinate values of an XYZ coordinate system are described in Table 1. In the XYZ coordinate system, a Y-axis direction is a toe-heel direction; a Z-axis direction is an up-down direction; and an X-axis direction is a direction perpendicular to the Y-axis and the Z-axis. 
     In respect of exact evaluation, the specific gravities of the face part, the front part, and the connecting part were adjusted so that a position of a center of gravity and a head weight of Examples 3 coincide with a position of a center of gravity and a head weight of Comparative Example. Specifically, as shown in Table 1, the specific gravity of each part was set to 2.0. By the adjustment, the positions of the center of gravity and the sweet spot of Example 3 mostly coincided with the positions of the center of gravity and the sweet spot of Comparative Example. Furthermore, the head weight of Example 3 coincided with the head weight of Comparative Example. Therefore, an effect based on the structure could be correctly evaluated. The difference between the coefficients of restitution of Example 3 and Comparative Example is considered to be caused by the difference between the structures of Example 3 and Comparative Example. 
     Simulation for making a ball collide with the heads of Example 3 and Comparative Example was carried out. The ball was made to collide with a stationary head at a speed 48.77 m/s in a state where a face surface of the head was set to be perpendicular to the direction of movement of the ball. Hit points were set to the following three places. 
     (1) standard hit point Hp 
     (2) 5 mm lower from standard hit point Hp 
     (3) 10 mm lower from standard hit point Hp 
     In Example 3 and Comparative Example, a distance in an up-down direction between the standard hit point Hp and a leading edge was 16 mm. A ball placed on a ground (lawn) is often hit by a fairway wood. For this reason, a point hit at a comparatively high frequency is near the standard hit point Hp. In the cases of Example 3 and Comparative Example, a face center Fc was located 3 mm lower from the standard hit point Hp. 
       FIGS. 43A and 43B  show a simulation image in Example 3.  FIG. 43A  shows a state where a golf ball gb 1  collides with the standard hit point Hp.  FIG. 43B  shows a state where the golf ball gb 1  collides with a point located 10 mm lower from the standard hit point Hp. 
     As a result of the simulation, the coefficients of restitution were as follows. 
     (1) hit point: standard hit point Hp
         coefficient of restitution of Example: 0.8644   coefficient of restitution of Comparative Example: 0.8659       

     (2) hit point: 5 mm lower from standard hit point Hp
         coefficient of restitution of Example: 0.8473   coefficient of restitution of Comparative Example: 0.8227       

     (3) hit point: 10 mm lower from standard hit point Hp
         coefficient of restitution of Example: 0.8320   coefficient of restitution of Comparative Example: 0.7908       

     If the hit point was the standard hit point Hp, coefficients of restitution of both Example and Comparative Example mostly coincided with each other. Meanwhile, if the hit point was located lower than the standard hit point Hp, the coefficient of restitution of Example was improved as compared with the coefficient of restitution of Comparative Example. Furthermore, the improvement rate of the coefficient of restitution was larger as the hit point was located on a lower side. That is, while the improvement rate when the hit point was located 5 mm lower was 3.0%, the improvement rate when the hit point was located 10 mm lower was 5.2%. Thus, the structure of Example was confirmed to cause the improvement in the coefficient of restitution of the lower edge part of the face. The advantages of the present invention are apparent. 
     The invention can be applied to all golf club heads such as a wood type, utility type, hybrid type, iron type, and putter type golf club heads. 
     The above description is only illustrative and various changes can be made without departing from the scope of the present invention.