# Patent

## Title
Golf club head

## Abstract

An iron-type golf club head includes a striking face; a base surface opposite the striking face; and a perimeter weighting element surrounding the base surface and including a top-line portion, a sole portion, a heel portion, and a toe portion. A first auxiliary cavity is delimited by the perimeter weighting element and a first perimeter wall, the first perimeter wall coupled to the sole portion and to the heel portion of the perimeter weighting element. A second auxiliary cavity is delimited by the perimeter weighting element and a second perimeter wall, the second perimeter wall coupled to the sole portion and to the toe portion of the perimeter weighting element. A central cavity is at least partially delimited by the base surface, the perimeter weighting element, the first perimeter wall, and the second perimeter wall, and an insert is within the central cavity.

## Background
RELATED U.S. APPLICATION DATA
This is a Continuation Application of application Ser. No. 14/105,991 filed on Dec. 13, 2013, which is in turn a Continuation of application Ser. No. 13/728,036 filed on Dec. 27, 2012, which in turn is a Continuation of application Ser. No. 13/464,100 filed on May 4, 2012, which is a Continuation of application Ser. No. 12/837,806 filed Jul. 16, 2010, which is a Continuation of application Ser. No. 12/071,132 filed Feb. 15, 2008 (now U.S. Pat. No. 7,789,771). The prior applications, including the specifications, drawings and abstracts are incorporated herein by reference in their entirety.


The disclosure below may be subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the documents containing this disclosure, as they appear in the Patent and Trademark Office records, but otherwise reserves all applicable copyrights.
BACKGROUND
Iron-type golf club heads may generally be classified into “blade” and “perimeter-weighted” categories. Perimeter-weighted iron-type golf club heads may have a substantial concentration of mass distributed behind the striking surface in the form of at least one peripheral wall, sometimes called the perimeter-weighting element. A perimeter-weighted iron-type golf club head may also be referred to as a “cavity-back” iron head, or simply a “cavity-back”, because the perimeter-weighting element thereof generally delimits a cavity in the rear portion of the club head opposite the striking face.
Perimeter-weighted irons are typically more “forgiving” than those of the blade type because the elevated moment of inertia generally associated with perimeter-weighted designs results in decreased head rotation when a ball is mishit, or struck away from the point of orthogonal projection of the club head's center of gravity onto the striking surface of the iron. Diminished rotation of the club head at impact may increase the accuracy and distance of such mishit shots. Thus, perimeter-weighted irons may substantially benefit less skilled golfers, who are likely to mishit the ball.
Various improvements for cavity-back iron heads, such as localized mass concentrations along the perimeter-weighting element, have been proposed. For example, it is well known that lowering the club head's center of gravity generally increases ball-launch angle at impact, thus facilitating shots from a variety of lies. Accordingly, sole-weighted cavity-back iron heads help improve ball-launch conditions.
In addition to mass-distribution improvements, a variety of vibration-attenuation technologies have been proposed for cavity-back irons. Some examples comprise a constrained-layer damper positioned behind the striking face within the rear cavity. Others include a resilient insert centrally disposed in the rear cavity. Typically, such inserts are made from materials having vibration-damping characteristics and low density.
However, club heads comprising a resilient insert located in the rear cavity may lack sufficient tactile feedback for a player to distinguish a well-made shot from a mediocre one. In addition, even though club heads fitted with constrained-layer dampers provide abatement of undesirable dynamic-excitation-response modes for a range of mishit shots, unfavorable dynamic-excitation-response modes associated with, e.g., extreme heel and toe mishits for such club heads remain problematic.
SUMMARY
The present invention, in one or more aspects thereof, may advantageously comprise a golf club head having improved forgiveness on mishit shots, enhanced tactile feedback, increased structural integrity, and reduced hook/slice tendencies.
In one example, a golf club head according to one or more aspects of the present invention may include a base surface located rearward of the striking surface and an insert associated with the base surface. The insert includes at least two contact elements and a bridge member disposed therebetween. At least a portion of each contact element of the insert may be associated with the base surface of the club head, whereas the bridge member of the insert may be dissociated from the base surface.
In another example, a golf club head according to one or more aspects of the present invention may include an insert and a main cavity comprising a first auxiliary cavity and a second auxiliary cavity. One portion of the insert may be disposed in the first auxiliary cavity and another portion of the insert may be disposed in the second auxiliary cavity.
In another example, a golf club head according to one or more aspects of the present invention may include a rear surface and a main cavity formed in the rear surface. The main cavity may comprise a base surface having an organic coating disposed on less than about 50% of the base surface. Additionally, an insert may be coupled to the base surface by an adhesive.
In yet another example, a golf club head according to one or more aspects of the present invention may be manufactured by providing a semi-finished club head with a rear surface comprising a main cavity including a base surface; placing a masking material on at least about 50% of the base surface; applying an organic to at least a portion of the base surface devoid of the masking material; removing the masking material; and bonding an insert to at least a portion of the base surface.
These and other features and advantages of the golf club head according to the invention in its various aspects as provided by one or more of the examples described in detail below will become apparent after consideration of the ensuing description, the accompanying drawings, and the appended claims. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the present invention.



BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary implementations of the present invention will now be described with reference to the accompanying drawings, wherein:
FIG. 1a is a front perspective view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 1b is another front perspective view of the golf club head of FIG. 1a. 
FIG. 1c is a rear perspective view of the golf club head of FIG. 1a. 
FIG. 1d is another rear perspective view of the golf club head of FIG. 1a. 
FIG. 1e is another rear perspective view of the golf club head of FIG. 1a. 
FIG. 2 is a rear perspective view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 3 is a rear perspective view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 4 is a rear perspective view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 5 is a rear perspective view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 6 is a rear perspective view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 7a is a rear elevational view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 7b is a cross-sectional view taken along the lines VIIb-VIIb of FIG. 7a. 
FIG. 8 is an exploded rear perspective view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 8a is a cross-sectional view of a vibration-attenuating feature taken along the lines VIIIa-VIIIa of FIG. 8.
FIGS. 8b and 8c are cross-sectional views of exemplary vibration-attenuating features of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 9 is an exploded rear perspective view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 10a is an exploded rear perspective view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 10b is another rear perspective view of the golf club head of FIG. 10a. 
FIG. 11 is a front perspective view of an insert for a golf club head in accordance with one or more aspects of the present invention.
FIG. 12 is a rear elevational view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 13 is a front perspective view of an insert for a golf club head in accordance with one or more aspects of the present invention.
FIG. 14 is a rear perspective view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 15 is an exploded rear perspective view of an exemplary golf club head in accordance with one or more aspects of the present invention.
FIG. 16 is an exploded rear elevational view of an exemplary golf club head in accordance with one or more aspects of the present invention.



DETAILED DESCRIPTION
Referring to FIGS. 1a and 1b, an iron-type golf club head 100, according to one or more aspects of the present invention, may generally comprise a front surface 102 that may be substantially planar over a majority of its area and delimited by a top line 104, a toe 106, a heel 108, and a sole 110. The heel 108 may generally comprise a heel surface 107 and the sole 110 may comprise a sole surface 109. The head 100 may further comprise a hose 112 for attaching a shaft (not shown) to the head. Referring again to FIG. 1a, the top line 104 may comprise a top line surface 103 and the toe 106 may comprise a toe surface 105.
With reference to FIGS. 1c and 1d, the head 100 may further comprise a rear surface 120 having a main cavity 130. The rear surface 120 may be bounded at its outer extent by the top line surface 103, the toe surface 105, the heel surface 107, and the sole surface 109. The main cavity 130 includes a base surface 132, surrounded, at least in part, by a perimeter surface 134, extending from the base surface 132 to the rear surface 120. The club head 100 may also comprise a perimeter weighting element 140, defined by the volume of material bounded by the perimeter surface 134, the rear surface 120, the top line surface 103, the toe surface 105, the heel surface 107, and the sole surface 109.
With reference to FIG. 1e, the main cavity 130 of the exemplary golf club head 100 may further comprise at least one auxiliary cavity, e.g., auxiliary cavities 150a and 150b. Each auxiliary cavity may be delimited by a perimeter wall, e.g., the perimeter walls 154a and 154b, a perimeter surface 134, and a base surface 132. While the auxiliary cavities are shown generally opposite the sole surface 109, these cavities may be located opposite any portion of the top line surface 103, the toe surface 105, the heel surface 107, and/or the sole surface 109.
As shown in FIG. 2, an exemplary golf club head 200, according to one or more aspects of the present invention, may comprise a main cavity 230 bounded by a base surface 232 and a perimeter surface 234. At least one auxiliary cavity, e.g., auxiliary cavities 250a and 250b, may be disposed in the perimeter surface 234. The auxiliary cavities 250a and 250b may be bounded by side walls 255a and 255b, respectively, and bottom surfaces 257a and 257b, respectively. Although the cavities are shown to be disposed generally opposite a sole surface 209, the cavities may be located opposite any portion of a top line surface 203, a toe surface 205, a heel surface 207, and/or the sole surface 209. As illustrated in FIG. 3, auxiliary cavities, e.g., cavities 350a and 350b, may be bounded by side walls 355a and 355b, respectively, bottom surfaces 357a and 357b, respectively, and portions of a base surface 332.
Referring to FIG. 4, an exemplary golf club head 400, according to one or more aspects of the present invention, may comprise a main cavity 430 bounded by a base surface 432 and a perimeter surface 434. At least one auxiliary cavity, e.g., auxiliary cavities 450a and 450b, may be bounded by side walls 455a and 455b, respectively, perimeter walls 454a and 454b, respectively, bottom surfaces 457a and 457b, respectively, and portions of a base surface 432. Although the auxiliary cavities are shown to be disposed generally opposite a sole surface 409, the cavities may be located opposite any portion of a top line surface 403, a toe surface 405, a heel surface 407, and/or the sole surface 409.
With reference to FIG. 5, an exemplary golf club head 500, according to one or more aspects of the present invention, may comprise a main cavity 530 having a single auxiliary cavity 550. The cavity 550 may be bounded by a perimeter wall 554, a perimeter surface 534, and a base surface 532. Although the auxiliary cavity is shown to be disposed generally opposite a sole surface 509, the cavity may be located opposite any portion of a top line surface 503, a toe surface 505, a heel surface 507, and/or the sole surface 509.
As shown in FIG. 6, a golf club head 600, according to one or more aspects of the present invention, may comprise a main cavity 630 having at least one auxiliary cavity, e.g., auxiliary cavities 650a and 650b. The cavities 650a and 650b may be bounded by a perimeter surface 634, portions of a base surface 632, and perimeter walls 654a and 654b, respectively, having a shared portion 668. Although the auxiliary cavities are shown to be disposed generally opposite a top line surface 603, the cavities may be located opposite any portion of a sole surface 609, a toe surface 605, a heel surface 607, and/or the top line surface 603.
As shown in FIGS. 7a and 7b, a golf club head 700, according to one or more aspects of the present invention, may comprise a main cavity 730 having three or more auxiliary cavities, e.g., auxiliary cavities 750a-d. Each auxiliary cavity may be bounded by a base surface 732, a perimeter surface 734, and a perimeter wall, e.g., one of auxiliary perimeter walls 754a-d. The reinforcement of the base surface 732 provided by the perimeter walls of the auxiliary cavities may deliver improved dynamic-excitation response of the club head at ball impact. As described in detail below, additional elements may be incorporated into the club head to further enhance the dynamic-excitation response thereof.
Referring to FIG. 8, a golf club head 800, according to one or more aspects of the present invention, may comprise a main cavity 830 having at least one auxiliary cavity, e.g., auxiliary cavities 850a-d. To improve the dynamic-excitation response of the head at ball impact, at least one vibration-attenuating feature may be disposed in at least one of the main cavity and the auxiliary cavities. For example, the vibration-attenuating feature may be a constrained-layer damper 880a that conforms to the shape of the main cavity 830. Examples of constrained-layer dampers are described in U.S. Pat. No. 5,316,298, which is hereby incorporated by reference.
The constrained-layer damper 880a is provided to improve the dynamic-excitation response of a golf club head at ball impact. Referring to FIG. 8a, damper 880a may include at least one constraining member 882a and a visco-elastic layer 884a. The layer 884a may comprise a visco-elastic stratum having, e.g., 3MTM VHBTM Adhesive Transfer Tape 9469. The damper 880a may be attached to the base surface 832 (FIG. 8) via the adhesive surface of the visco-elastic layer 884a. 
Referring to FIGS. 8b and 8c, constrained-layer dampers having a three-dimensional topography are illustrated. As shown in FIG. 8b, a damper 880b may comprise a non-planar constraining member 882b, a variable-thickness intermediate layer 886b, and a visco-elastic layer 884b. The intermediate layer 886b may include a non-planar surface 888b, complementing the corresponding mating surface of the constraining member, and an opposing substantially flat surface 890b. The intermediate layer 886b may be co-molded with the constraining member 882b or may be attached thereto, e.g., by an adhesive. The intermediate layer 886b may be a polymer, e.g., a two-part polyurethane such as MF440 resin activated by DK124HV hardener, or any other suitable material. The visco-elastic layer 884b may comprise, e.g., 3MTM VHBTM Adhesive Transfer Tape 9469.
In another example, a constrained-layer damper 880c, shown in FIG. 8c, may comprise a variable-thickness constraining member 882c and a visco-elastic layer 884c having adhesive surfaces. The constraining member may include a non-planar exterior surface 892c and an opposing substantially flat surface 890c. The constraining member 882c may be manufactured from a variety of materials including, but not limited to, plastics, metals, and composites.
The club head, according to one or more aspects of the invention, may be provided with additional features to improve the dynamic-excitation response for mishit shots. As shown in FIG. 9, an exemplary golf club head 900 may comprise a main cavity 930 having at least one auxiliary cavity, e.g., auxiliary cavities 950a-c. An insert 920, disposed in the auxiliary cavity 950a, may abut a base surface 932, a perimeter surface 934, and/or a perimeter wall 954. The insert 920 is provided, at least in part, for abatement of unfavorable vibrations, associated, e.g., with mishit shots. A secondary vibration-attenuating feature, e.g., a constrained-layer damper 980, may also be introduced to further improve the damping properties of the club head 900.
In another example, a golf club head 1000, shown in FIGS. 10a and 10b, may comprise a main cavity 1030 having at least two auxiliary cavities, e.g., auxiliary cavities 1050a-d. The club head 1000 may further comprise an insert 1020 having at least two contact elements, e.g., toe element 1022 and heel element 1023, and a bridge member 1024 disposed therebetween. Referring to FIG. 10b, the insert 1020 may be at least partially disposed in at least two auxiliary cavities, e.g., the auxiliary cavities 1050a and 1050b. For example, the heel element 1023 may be positioned in the auxiliary cavity 1050a and the toe element 1022 may be positioned in the auxiliary cavity 1050b. Preferably, the at least two contact elements abut a base surface 1032 of the main cavity. The bridge member 1024 may be dissociated from the base surface 1032 for the purposes of tuning the dynamic-excitation response of the club head, particularly for mishit shots. A secondary vibration-attenuating feature, e.g., constrained layer damper 1080, may also be provided to further improve the damping properties of the club head.
The insert 1020 may be made from a resilient material having a Shore hardness from about 50 A to about 75 D to provide a soft tactile sensation. In another example, the resilient material may have a Shore hardness from about 60 A to about 80 A. The tactilely perceptible softness of the insert may communicate to the golfer an improvement in the dynamic-response characteristics of the golf club head at ball impact, thus promoting increased player confidence in the equipment. Examples of the resilient materials suitable for fabricating the insert 1020 may include polyurethane, silicone, ABS, Nylon, polycarbonate (PC), polypropylene (PP), polyethylene (PE), thermoplastic rubber (TPR), thermoplastic vulcanizate (TPV), thermoplastic elastomers (TPE), and natural rubber. In another example, the insert 1020 may be made from thermoplastic polyurethane (TPU) having a Shore hardness between about 65 A and about 75 A. The specific gravity of the insert may depend on the material selected and may generally be between about 0.8 and about 2.0. Alternatively, the material selected may be densified by blending the resilient material with a higher-density powdered material, e.g., tungsten, prior to the formation of the insert 1020. The specific gravity of the densified insert may be in a range from about 0.8 to about 15. The insert may therefore be used to alter the weight distribution of the club head.
Referring again to FIGS. 10a and 10b, the insert 1020 may be bonded to the head 1000 using, e.g., an epoxy-type adhesive. The adhesive may be applied to the base surface 1032, the perimeter surface 1034, and the interior surfaces of two perimeter walls 1054a and 1054b. 
Referring to FIG. 11, an insert, according to one or more aspects of the present invention, e.g., an insert 1120, may comprise one or more ridges 1128 on at least one of the at least two contact elements, e.g., a toe element 1122 and a heel element 1123. The gaps between the ridges may help reduce adhesive “squish-out” when fitting the insert to the club head during assembly. Moreover, the ridges 1128 may promote a stronger bond between the club head and the insert by increasing the area of the bonding interface. As shown in FIG. 11, the ridges 1128 may be disposed on the insert in any desired orientation.
In another aspect of the present invention, a golf club head 1200, shown in FIG. 12, may comprise a main cavity 1230, having at least three auxiliary cavities, e.g., auxiliary cavities 1250a-d, and a central cavity 1250e. The auxiliary cavities 1250a-d may serve as examples of first through fourth cavities or partitions, and the central cavity 1250e may serve as an example of a fifth cavity or partition. The club head 1200 may further comprise an insert 1220, having at least three contact elements, e.g., toe elements 1222a, 1222b and heel elements 1223a, 1223b, with a bridge member 1224 disposed therebetween. As shown in FIG. 12, the insert 1220, illustrated by hatching, may be at least partially disposed in at least three auxiliary cavities. For example, the heel elements 1223a and 1223b may be positioned in the auxiliary cavities 1250a and 1250c, respectively, and the toe elements 1222a and 1222b may be positioned in the auxiliary cavities 1250b and 1250d, respectively. Preferably, the at least three contact elements are in contact with a base surface 1232 of the main cavity. As shown in FIG. 12, the heel elements 1223a, 1223b and the toe elements 1222a, 1222b of the insert 1220 may cover, or span, the entire base surface 1232 of the auxiliary cavities 1250a-d. The bridge member 1224 may be dissociated, or separate, from the base surface 1232 for the purposes of tuning the dynamic-excitation response of the club head, particularly on mishit shots.
According to the USGA Rules, all parts of a golf club head must be fixed. In other words, no part of a golf club head may exhibit movement relative to any other part thereof when subject to an external force. Absent additional underpinnings, the bridge members of the exemplary inserts, described above with reference to FIGS. 10a-12, may deflect when subjected to external forces. For example, referring to FIG. 10h, the bridge member 1024 may deflect toward the base surface 1032 when a force is applied to the bridge member in the direction of the base surface. As shown in FIGS. 13-15, auxiliary elements may be incorporated into the club head and/or the insert to substantially inhibit movement of the insert relative the club head.
With reference to FIG. 13, an insert 1320, according to one or more aspects of the present invention, may comprise at least two contact elements, e.g., heel element 1322 and toe element 1323, with a bridge member 1324 disposed therebetween. The insert 1320 may further comprise a stiffening member 1326 extending, e.g., from the heel element 1322 to the toe element 1323 along the bridge member 1324. The stiffening member 1326 may be flush with the insert 1320, at least in part, recessed, at least in part, and/or salient, at least in part. Regardless of the configuration, the stiffening member 1326 is provided to prevent the insert 1320 from deflecting, e.g., more than about 1 mm (0.040 in.) relative to the club head with the application of about 45 N (10 lb) of force. The applied force should generally correspond to the typical force delivered by the thumb of a golfer or a golf official who may wish to test the head for conformance with the applicable rules of golf.
Referring again to FIG. 13, the stiffening member 1326 may be formed from a polymeric material, such as ABS, Nylon, PVC, Polystyrene, Polypropylene, High Density Polyethylene, glass- or carbon-fiber-reinforced plastic, or the like. Metallic materials, e.g., aluminum, steel, magnesium, titanium, or the like, may also be used. In general, the material selected should provide sufficient stiffness to realize the deflection criteria discussed above. In one example, the stiffening member 1326 may be attached to the insert 1320, e.g., by adhesive bonding or other known methods. Alternatively, the parts of the insert may be integrally co-molded.
In another example, shown in FIG. 14, a golf club head 1400, according to one or more aspects of the present invention, may comprise a main cavity 1430, having a perimeter surface 1434 and a stiffening member 1426 disposed on the perimeter surface. As shown in FIG. 14, the stiffening member 1426 may have an arch-like configuration for buttressing the bridge member of any exemplary insert described with reference to FIGS. 10a, 10b, 11, 12, and 13 above. Such a construction may sufficiently stiffen such an insert to conform to the rules of golf. The stiffening member may be formed separately from the head 1400 and may be attached thereto, e.g., by adhesive bonding, welding, or other joining techniques. Alternatively, the stiffening member may be cast integrally with the head. Adhesives may be employed at the interface between the insert and the stiffening member 1426 to further stabilize and anchor the insert to the club head.
With reference to FIG. 15, a golf club head 1500, according to one or more aspects of the present invention, may comprise an insert 1520 and a perimeter surface 1534 having a stiffening member 1526. The stiffening member 1526 may protrude from the perimeter surface 1534 for engagement with a complementary opening 1527 formed in the insert 1520. Engagement of the insert 1520 with the stiffening member 1526 substantially vitiates the deflection of the insert relative to the club head. As shown in FIG. 15, the stiffening member 1526 and the complimentary opening 1527 may, for example, comprise generally rectangular shapes. As described above, adhesives may be employed at the interface between the insert 1520 and the stiffening member 1526 to further stabilize and anchor the insert to the club head.
It may also be desirable to enhance the cosmetic appeal of the club head, according to one or more aspects of the present invention, with the use of organic surface coatings, e.g., paint or the like. However, the application of such coatings to the club head may lead to a weak bond between the club head and any supplementary vibration-attenuation components, such as those described above. Thus, specific preparation of the club head surface is necessary for the durability of any adhesive bond between the club head and its bonded components. Such surface preparation may include cleaning the head with solvents or other chemicals and subsequently treating any surfaces that will have an adhesive and/or coating applied thereto with an abrasive medium. Organic surface coatings should be applied to the head prior to the attachment of any supplementary components to avoid staining the supplementary components with the coating.
Referring to FIG. 16, a golf club head 1600, according to one or more aspects of the present invention, may comprise a main cavity 1630 having a base surface 1632 and at least one auxiliary cavity, e.g., auxiliary cavities 1650a-d. Subsequent to any desired surface preparation step, such as the exemplary steps described above, one or more sections of a masking material 1611 may be applied to at least a portion of one or more regions of the main cavity 1630, where at least one supplementary component will subsequently be adhesively bonded. The masking material 1611 may be configured to cover at least about 50% of one or more regions of the base surface 1632 where at least one supplementary component will be attached. In other examples, the masking material may cover at least about 60% of one or more of the above-mentioned regions or at least about 80% of the above-mentioned regions. The organic surface coating 1652 is then applied to the portion of the club head that is devoid of the masking material 1611. Following the application of the organic coating, the masking material is removed. The supplementary components, such as inserts and/or constrained-layer dampers, are then coupled to the desired regions of the base surface 1632 having areas devoid of the organic coating, thus promoting a durable bond between the club head and any such supplementary component.
In the foregoing specification, the invention has been described with reference to specific exemplary aspects thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

## Claims

1. An iron-type golf club head comprising:
a striking face;
a base surface opposite the striking face;
a perimeter weighting element surrounding the base surface and including a top-line portion, a sole portion, a heel portion, and a toe portion;
a first auxiliary cavity delimited by the perimeter weighting element and a first perimeter wall, the first perimeter wall coupled to the sole portion and to the heel portion of the perimeter weighting element and distal to the top-line portion and the toe portion,
a second auxiliary cavity delimited by the perimeter weighting element and a second perimeter wall, the second perimeter wall coupled to the sole portion and to the toe portion of the perimeter weighting element and distal to the top-line portion and the heel portion,
a central cavity at least partially delimited by the base surface, the perimeter weighting element, the first perimeter wall, and the second perimeter wall; and
an insert within the central cavity.

2. The iron-type golf club head of claim 1, wherein the insert includes a constrained-layer damper.

3. The iron-type golf club head of claim 1, wherein the insert comprises a durometer hardness between about 60 Shore A and about 80 Shore A.

4. The iron-type golf club head of claim 1, wherein the insert comprises a specific gravity between about 0.8 and about 2.0.

5. The iron-type golf club head of claim 1, wherein the insert is recessed inwardly toward the base surface relative to a rear surface of the perimeter weighting element.

6. The iron-type golf club head of claim 1, wherein the insert is adhesively coupled to the base surface.

7. The iron-type golf club head of claim 1, wherein the insert spans at least the distance between the first auxiliary cavity to the second auxiliary cavity in a heel to toe direction.

8. The iron-type golf club of claim 1, wherein the first auxiliary cavity has a smaller heel to toe length than the second auxiliary cavity.

9. The iron-type golf club of claim 1, wherein the insert extends substantially along the entirety of the base surface of the central cavity.

10. The iron-type golf club of claim 1, wherein the first and second auxiliary cavities are visually exposed.

11. An iron-type golf club head comprising:
a striking face;
a base surface opposite the striking face;
a perimeter weighting element surrounding the base surface and including a top-line portion, a sole portion, a heel portion, and a toe portion;
a first auxiliary cavity delimited by the perimeter weighting element and a first perimeter wall, the first perimeter wall coupled to the sole portion and to the heel portion of the perimeter weighting element,
a second auxiliary cavity delimited by the perimeter weighting element and a second perimeter wall, the second perimeter wall coupled to the sole portion and to the toe portion of the perimeter weighting element,
a third auxiliary cavity delimited by the base surface, the top-line portion of the perimeter weighting element, the heel portion of the perimeter weighting element, and a third perimeter wall;
a fourth auxiliary cavity delimited by the base surface, the top-line portion of the perimeter weighting element, the toe portion of the perimeter weighting element, and a fourth perimeter wall;
a central cavity delimited by the base surface, the perimeter weighting element, the first perimeter wall, the second perimeter wall, the third perimeter wall, and the fourth perimeter wall; and
an insert within the central cavity.

12. The iron-type golf club head of claim 11, wherein the insert includes a constrained-layer damper.

13. The iron-type golf club head of claim 11, wherein the insert comprises a durometer hardness between about 60 Shore A and about 80 Shore A.

14. The iron-type golf club head of claim 11, wherein the insert comprises a specific gravity between about 0.8 and about 2.0.

15. The iron-type golf club head of claim 11, wherein the insert is recessed inwardly toward the base surface relative to a rear surface of the perimeter weighting element.

16. The iron-type golf club head of claim 11, wherein the insert is adhesively coupled to the base surface.

17. The iron-type golf club head of claim 11, wherein the insert spans at least the distance between the first auxiliary cavity to the second auxiliary cavity in a heel to toe direction.

18. The iron-type golf club of claim 11, wherein the first auxiliary cavity has a smaller heel to toe length than the second auxiliary cavity.

19. The iron-type golf club of claim 11, wherein the insert extends substantially along the entirety of the base surface of the central cavity.

20. The iron-type golf club of claim 11, wherein the first and second auxiliary cavities are visually exposed.

21. The iron-type golf club of claim 11, wherein the third and fourth perimeter walls are part of a unitary structure.