BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a golf club head with a polymer insert. More specifically, the present invention relates to a golf club head with a laser welded polymer insert.  
         [0003]     2. Description of the Related Art  
         [0004]     Throughout the history of golf, which dates back to as early as 1457, various techniques have been used to enhance the hitting characteristics of golf club heads. Golf club heads having inserts for the striking portion have been used at least as far back as 1880&#39;s when leather face irons were manufactured in Scotland. Golfer&#39;s in the 1890&#39;s were able to purchase putters with faces composed of gutta percha. More recently, inserts composed of various materials and shapes have been put forth by the creative geniuses of the golf industry to provide golfers with better feel and control of the golf ball.  
         [0005]     One example is an ODYSSEY® putter having a STRONOMIC® insert that is disclosed in Magerman et al., U.S. Pat. No. 5,575,472 for a Golf Putter Head Having Face Insert And Method Of Forming The Same. The Magerman et al. Patent discloses a putter head with a recess into which is poured or inserted a resinous material which cures and is subsequently milled to produce the putter.  
         [0006]     Another example is Pond, U.S. Pat. No. 5,524,331 for a Method For Manufacturing Golf Club Head With Integral Inserts that discloses a method for casting a graphite-epoxy composite insert within a recess of a face of a metal club head. The golf club head of the Pond Patent is directed at displacing the weight away from the center and increasing the moment of inertia.  
         [0007]     Another example is Schmidt et al., U.S. Pat. No. 5,485,997, for a Golf Putter Head With Face Plate Insert Having Heightened Medial Portion, that discloses a putter head with a face plate composed of a non-metallic material such as an elastomer. The overall construction of the putter head of the Schmidt et al. Patent is directed at enlarging the sweet spot and improving the peripheral weighting.  
         [0008]     Yet another example is found in Baker et al., U.S. Pat. No. 5,931,743 for a Putter Having Club Head With A Golf-Ball Engagement Insert And A Shaft Rearwardly Of The Insert which discloses a putter with a center shaft and an insert composed of a thermoplastic polyurethane. Another example is Jepson et al., U.S. Pat. No. 3,937,474 for a Golf Club With Polyurethane Insert, which discloses a wood having an insert on its striking face that is composed of a polyurethane formed from a tolylene diisocyanate polyether terminated prepolymer and a curing agent. The hardness of this insert varies from 40 to 75 Shore D, and a Bayshore Resiliometer of 17 or above. The polyurethane insert is claimed to impart additional energy to the golf ball during a golf hit.  
         [0009]     Chen et al., U.S. Pat. No. 5,743,813 for a Golf Club Head discloses a wood composed of stainless steel with a three layer face having a first stainless steel layer, an elastic layer and a second stainless steel layer. The three-layer face does not absorb the hitting force when a golf ball is hit.  
         [0010]     Fisher, U.S. Pat. No. 5,458,332, for a Golf Putter Head With A Cushioning Face, discloses a set of golf putters, each having an insert composed of polyurethane with a hardness in the range of 70 Shore A to about 80 Shore D. The rebound factor of each of the inserts is in the range of 12.5% to 50%, and the inserts are formulated to affect a reproducible direct linear relationship between the rebound factor and the distance of the putt.  
         [0011]     Yet another example is McGeeney et al, European Patent Application Number 0891790 for a Multiple Density Golf Club Head And Method Of Manufacturing which discloses a putter with a central segment composed of a thermoplastic elastomer or a thermoset polymer. Possible thermoplastic elastomers include styrene co-polymers, co-polyesters, polyurethanes, polyamides, olefins and vulcanates. Possible thermoset polymers include epoxides, polyimides and polyester resins. The central segment has a minimum durometer hardness of Shore D 50. The central segment is bounded by metallic heel and to portions. However, the use of inserts is restrained in order to maintain the integrity of the game of golf.  
         [0012]     In this regard, the Rules of Golf, established and interpreted by the United States Golf Association (“USGA”) and The Royal and Ancient Golf Club of Saint Andrews, sets forth certain requirements for a golf club head. The requirements for a golf club head are found in Rule 4 and appendix II. A complete description of the Rules of Golf are available on the USGA web page at www.usga.org. Although the Rules of Golf do not expressly state specific parameters for an insert for a putter, the Rules of Golf have been interpreted to establish that an insert for a putter should have a Shore A hardness greater than 87±2%, have a constant thickness, have a thickness of at least 0.125 inches, and not act like a spring.  
         [0013]     The prior art is absent a golf club head that has an insert composed of a material that is soft, but above the USGA requirements, and has a sufficient Bayshore rebound to provide a golf ball with the necessary distance to reach the hole.  
       BRIEF SUMMARY OF THE INVENTION  
       [0014]     The present invention is directed at a method for manufacturing a golf club head with an insert using laser welding. The use of laser welding allows for a base insert to have an indicia that is visible through a transparent polymer insert.  
         [0015]     Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE INVENTION  
       [0016]      FIG. 1  is a perspective view of one embodiment of the golf club head of the present invention without an insert in the recess of the club head body.  
         [0017]      FIG. 1A  is a front view of the club head of  FIG. 1  with the insert placed therein.  
         [0018]      FIG. 1B  is a side view of the club head of  FIG. 1 .  
         [0019]      FIG. 1B  is a rear view of the club head of  FIG. 1 .  
         [0020]      FIG. 1D  is a top view of the club head of  FIG. 1 .  
         [0021]      FIG. 2  is a front view of the club head of  FIG. 1 .  
         [0022]      FIG. 3  is a front view of a club head with an insert having an indicia thereon.  
         [0023]      FIG. 4  is a cross-section view of the club head of  FIG. 2  along line  4 - 4 .  
         [0024]      FIG. 5  is an exploded view of a club head with two inserts.  
         [0025]      FIG. 6  is an isolated enlarged view of the transition region between the two inserts of a club head.  
         [0026]      FIG. 7  is an exploded cross-section view of a club head with two inserts.  
         [0027]      FIG. 8  is a side view of a precursor club head undergoing laser welding.  
         [0028]      FIG. 9  is a flow chart of a general method of laser welding.  
         [0029]      FIG. 10  is a front view of a wood club head with an insert.  
         [0030]      FIG. 11  is a front view of an iron club head with an insert.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]     As shown in  FIGS. 1 through 1 D, a putter is generally designated  50 . The putter  50  includes a club head  52  having a body  54  with a front face  56  with a recess  58  therein. The club head  52  also includes a transparent polymer insert  60  disposed within the recess  56 . The transparent polymer insert  60  preferably extends along most of the face  56  from a heel  62  of the club head  52  to a toe  64  of the club head  52 , and from a sole  66  of the club head  52  to a crown  68  of the club head  52 . The club head  52  also preferably has a hosel  70  for connection to a shaft  72 . Opposite of the front face  56  of the club head  52  is a rear  74  of the club head  52 .  
         [0032]     The body  54  of the club head  52  is preferably composed of a metallic material such as titanium, titanium alloy, amorphous metals, brass, carbon steel, or stainless steel. However, those skilled in the pertinent art will recognize that the body  54  may be composed of other materials without departing from the scope and spirit of the present invention. Further, the non-insert portion of the face  56  may be smooth or textured to provide a consistent or non-consistent surface with the exterior surface of the insert. Additionally, the body  54  may be specifically weighted to provide a specific center of gravity for the putter  50 .  
         [0033]     The putter  50  illustrated in  FIGS. 1-1D  is flanged blade putter, however, those skilled in the pertinent art will recognize that other similar putter designs such as a mallet or semi-mallet may be utilized without departing from the scope and spirit of the present invention.  
         [0034]     Referring specifically to  FIG. 1 , the recess  58  of the body  54  is defined by a recess face wall  80  which is substantially parallel with the transparent polymer insert  60 , and a recess edge wall  82  which is substantially perpendicular to the recess face wall  80 . The recess face wall  80  defines the depth of the recess  58 . The recess edge wall  82 , as shown in  FIG. 1 , is composed of a bottom recess edge wall  82   a , a heel recess edge wall  82   b , a top recess edge wall  82   c  and a toe recess edge wall  82   d . The recess edge wall  82  defines the shape of the recess  58 , and the length of the recess edge wall  82  is determined by the depth of the recess  58 .  
         [0035]     The putter  50  of  FIGS. 1-1D  is a flanged blade style putter. The rear  74  of the club head  52  has a rear wall  75  and a flanged portion  77 . The transparent polymer insert  60  preferably occupies more than 80% of the area of the face  56  of the club head  52 . The transparent polymer insert  60  varies in shape and thickness depending on the design of the putter  50 . A preferred shape of the transparent polymer insert  60  is a trapezoidal shape with curved corners. An alternative shape is a trapezoidal shape with a panhandle, not shown.  
         [0036]     As shown in  FIGS. 2-5  and  7 , a preferred embodiment of the club head  52  has a base insert  61  that is preferably adhered to the recess face wall  82 . The base insert  61  preferably has a thickness that ranges from 1.0 millimeter to 10 millimeters, more preferably from 1.5 millimeters to 7 millimeters, and even more preferably 2.0 millimeters to 5.0 millimeters, and most preferably 3.0 millimeters. The transparent polymer insert  60  preferably has a thickness that ranges from 1.0 millimeter to 10 millimeters, more preferably from 1.5 millimeters to 7 millimeters, and even more preferably 2.0 millimeters to 5.0 millimeters, and most preferably 3.0 millimeters. In a preferred embodiment, the thickness of both the base insert  61  and the transparent polymer insert  60  defines the depth of the recess  58 .  
         [0037]     The base insert  61  is preferably colored, as opposed to transparent. In a preferred embodiment, the base insert  61  has a heat absorbing color. Most preferably the color is selected from the group of black, blue (navy, royal, marine, light), brown, purple, red, orange, grey, green or other similar colors.  
         [0038]     The polymer material for the transparent polymer insert  60  and the base insert  61  is preferably a thermoplastic polyurethane material. Alternative polymer materials that may be utilized for the transparent polymer insert  60  and the base insert  61  include: polymers from Bayer Corporation sold under the TEXIN brand such as TEXIN 4215, TEXIN 4210, TEXIN 270, TEXIN 4210 T2, TEXIN 270 T2, TEXIN 4215 T2 and TEXIN 4215 T3, which are thermoplastic polyurethanes and thermoplastic polyurethane and polycarbonate blends; polymers from BASF corporation such as TERLURAN EGP-7, TERLURAN HI-10, TERLURAN GP-22, which are ABS polymers, ULTRAMID A3HG5, LURANS 778 T1 and LURAN S 778 T/TE T2, which are ABS and polyamide blends, and TRIAX 1120, which is an ABS and polyamide blend; polymers from Du Pont Chemicals such as HYTREL 7246 thermoplastic polyester elastomer and HYLENE 58D polymer and SURLYN ionomers; polymers from GE Polymers such as NORYL PPX/PPX7115 polyphenylene ether and polystryene blend, LEXAN EXL 1330 T2, LEXAN EXL 1330 T3, LEXAN ML 6143/C1000, LEXAN 1330/ML6143, LEXAN ML6143H and LEXAN 1330, which are amorphous thermoplastic polymers, CYCOLOY C1000HF T1, CYCOLOY C1000HF T2, CYCOLOY C1000HF T3, CYCOLOY C1000HF T4 AND CYCOLOY C1000HF T5, which are ABS and polycarbonate blends; polymers from Atofina corporation sold under the brands ATOFINA 3429, ATOFINA 3467 and ATOFINA 7823 MZ; polymers from BP Chemical sold under the brand BAREX 210, which is an E acrylonitrile-methyl acrylate copolymer; polymers from Chevron corporation sold under the brands BK-12, KR03 and BK10/NAS90 blend; polymers from Exxon Mobil chemical sold under the brands PP1024E4, PP1043N, PP7033N, PP7032E2T1, PP7032KN and PP7032E2T2; polymers from Huntsman Chemical sold under the brand IROGRAN 113557; polymers from RTP corporation sold under the brands 1299-A 80D w/glass, 1299-B 80D without glass, RTP 4085 and Nylon 6 with nano; polymers from Uniroyal sold under the brand AN2501750 blend T1, AN2501750 blend T2 and LF750D; and LUMOGEN IR 788 and LUMOGEN IR 765 from BASF.  
         [0039]     The Shore D hardness of the polymer material for the insert  60  preferably ranges from 40 to 70 Shore D, more preferably from 50 to 65 Shore D, and is most preferably approximately 60 Shore D. The base insert  61  preferably has a similar Shore D hardness.  
         [0040]     As shown in  FIG. 3 , a front surface  63  of the base insert  61  has an indicia  77  thereon. The indicia  77  is visible through the transparent polymer insert  60  and is protected during use from deterioration by the transparent polymer insert  60 . The indicia  77  is preferably a corporate logo, name of the golfer, greeting, or slogan. The indicia  77  is preferably printed on the front surface  63  of the base insert  61 . Alternatively, the indicia  77  is embossed of the front surface  63  of the base insert  61 .  
         [0041]     A general method of laser welding is generally designated  100 , as shown in  FIG. 9 . In a preferred embodiment, the method  100  involves laser welding the transparent polymer insert  60  to the base insert  61 . Laser welding involves passing laser light through the transparent polymer insert  60  (laser transparent polymer insert) onto the base insert  61  (laser absorbent polymer insert). The absorbed laser energy softens and melts the transparent polymer insert  60  and the base insert  61 . More precisely, the laser energy absorbed by the base insert  61  heats the base insert  61  which softens and melts a transition region  71  which includes the front surface  63  of the base insert  61  and an interior surface  65  of the transparent polymer insert  60 , as shown in  FIG. 6 . Upon cooling, the transparent polymer insert  60  is adhered to the base insert  61 .  
         [0042]     Returning the flow chart of  FIG. 9 , at step  102 , the base insert  61  is adhered to the recess face wall  82  of the recess  58  of the club head  52 . The base insert  61  is preferably adhered using an adhesive such as an epoxy. However, the base insert  61  alternatively may be mechanically adhered using bolts, press-fitting or other well-known methods. Next, at step  104 , the transparent polymer insert  60  is placed onto the front surface  63  of the base insert  61  and thereby fitted within the recess  58 . At step  106 , the transparent polymer insert  60  is irradiated with laser energy  91  from a laser device  90 , as shown in  FIG. 8 . The irradiation of laser energy is performed for a time period preferably ranging from 0.1 second to 10 minutes, and more preferably from 1.0 seconds to 1 minute. The irradiation period will depend on the materials utilized, the power of the laser and the thickness of the materials.  
         [0043]     The laser device is preferably an infrared laser having a wavelength ranging from 800 nanometers to 950 nanometers. A preferred laser device is a Nd-YAG diode laser. A preferred laser welding system is available from Dukane Company of St. Charles, Ill. Other laser welding systems commercially available include a POLYSCAN system, a STARWELD DIODE system and a STARSHAPE C system, all of which are available from Rofin-Sinar Technologies of Hamburg Germany.  
         [0044]     In an alternative embodiment, a laser absorbent polymer layer  61 ′ (not shown) is adhered to the recess face wall  82  as a substitute for the base insert  61 . In such an embodiment, the laser absorbent polymer layer  61 ′ absorbs the laser energy to melt the transparent polymer insert  60  for adherence thereto. The laser absorbent polymer layer  61 ′ has a thickness preferably ranging from 0.5 millimeters to 5 millimeters, and preferably has a heat absorbing color as discussed above.  
         [0045]      FIG. 10  is illustrates yet another utilization of the transparent polymer insert  60   a  and base insert  61 ′ (not shown) in a wood club head  52   a . The transparent polymer insert  60   a  occupies most of the face  56   a , from the heel  62   a  to the toe  64   a , and from the sole  66   a  to the crown  68   a . The body  54   a  of the club head  52   a  may be hollow, unlike the putters  50  of the previous embodiments. Further, the recess face wall, not shown, of the recess  58   a  will not abut the rear wall, not shown, unlike the putters  50  of the previous embodiments. The body  54   a  may be composed of titanium, or steel.  FIG. 11  illustrates a further embodiment where the transparent polymer insert  60   b  and base insert  61 ′ are used on the face  56   b  of an iron club head  52   b.    
         [0046]     From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes, modifications and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claims. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.
A method for laser welding a polymer insert within a recess of a golf club head is disclosed herein. Also disclosed is a golf club head having a laser welded polymer insert. The invention comprises laser welding a transparent polymer insert to a base polymer insert that has a heat absorbing color such as black or blue. The base polymer insert may also have an indicia thereon which is visible after laser welding the transparent polymer insert.