NZ242859A

NZ242859A - Set of golf club irons; geometric centre of each club head face coincides with centre of mass of the club head

Info

Publication number: NZ242859A
Application number: NZ242859A
Authority: NZ
Inventors: John B Hoeflich
Original assignee: Acushnet Co
Priority date: 1991-06-06
Filing date: 1992-05-22
Publication date: 1995-02-24
Also published as: EP0517487B1; EP0517487A1; AU652640B2; AU1801792A; JPH05154221A; CA2070565A1; DE69204358T2; DE69204358D1; ZA924115B

Description

242859 rrio.it, :.<uovW: .kk\?! Cuiii^lete Specificcticn Filed: Class: J9ft.

Publication Dei;: ..2AfEfU?95 P.O. Jovrnc', i: :■: /.«?*.? NEW ZEALAND PATENTS ACT, 1953 No.: Date: COMPLETE SPECIFICATION GOLF CLUB IRONS We, ACUSHNET COMPANY, a corporation of Delaware, United States of America, of New Bedford, MA 02745, United States of America, hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- (followed by page la) 28 A-166 GOLF CLUB IRONS This invention relates to golf clubs and, more particularly, to irons having a back cavity where the perimeter outside the back cavity is varied such that the geometric center of the face of the club head coincides with the center of mass of the club head.

Golf clubs comprise a shaft and a club head and are generally classified into three categories: woods, irons and putters. Irons are classified by loft angle. Irons with low loft angles, e.g. 20u-30°, are classified as long irons while irons with large loft angles, e.g. 40u-50u, are classified as short irons. Typically, irons are numbered from long to short, i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, PW (pitching wedge), SW (sand wedge), and LW (lob wedge).

The club head of an iron has a face, for hittin the golf ball, and a back. The back may have either a cavity or a smooth surface. Each face has an area referred to as a sweet spot. The sweet spot is that area on the face of a club head which, when it impacts a golf ball, provides the most favorable results. Cavity back irons have larger sweet spots than solid back irons. There have -ltL 242858 oeen suggestions to vary the size and position of the back cavity; see U.S. Patent Nos. 4,715,601 issued December 29, 1987 and 4,848,747 issued July 18, 1989. However, none of these references teach 5 the achieving of aligning the geometric center of the face of an iron with the center of gravity of the club head by varying the perimeter weight of the back of the club head.

It has now been discovered that an exceptionally 10 playable cavity back iron can be made by adjusting the perimeter weighting outside the cavity in the back of the iron so that the center of gravity of the club head and the geometric center of the face of the club head coincide.

According to the present invention it is important that the weight adjustment be in the perimeter of the club head and not in the cavity itself.

This achieves better heel-toe balance than can be achieved by adjusting the weight in the cavity 20 itself. It is especially desirable to maintain a flat cavity bottom. This can be achieved by maintaining a constant distance between the face and the cavity bottom throughout a substantial portion of the cavity.

In addition to adjusting the perimeter weight in the back of the club head, the hosel length of the irons is maintained at substantially the same length, preferably within ±.01 inch and most 5 preferably +.005 inch, while the ratio of the overall percentage of the club weight in the toe and sole is greater in the short irons than in the long irons.

The geometric center of the face is located by finding the mid-point of the blade length along 10 the sole and moving upward a distance about equal to the radius of a golf ball, from about H inch to about 1 inch (about 1.3 to about 2.5 cm). More preferably, the geometric center of the face is located about 0.8-0.9 inch (about 2.0-2.3 cm) up 15 from the mid-point of the blade as measured along the sole.

In order to produce an iron in accordance with the present invention, it is preferred that the offset of the club heads be greater in the 20 long irons than in the short irons, preferably decreasing progressively from long irons to short irons. As is well known to those in the art, offset is the distance from a plane tangent to the front of the hosel parallel to the leading edge of the 25 club to the leading edge. The progression of offset from the long to the short irons contributes to the performance of the iron. In long irons the larger offset helps keep the players' hands ahead of the ball at impact and promotes a steep angle of attack to get the ball airborne more quickly.

The bounce angle is also preferably varied.

As is well known to those in the art, bounce angle is the arcuate distance between the ground and the line which connects the leading edge of the sole with the trailing, or effective trailing, edge of the sole. Preferably, the longer irons have a negative 10 bounce angle while the middle irons have a neutral bounce angle and the shorter irons have a positive bounce angle. The bounce angle helps improve playability, launch angle and spin rate.

These and other aspects of the present invention 15 may be more fully understood by reference to the following drawings: Fig. 1 is a preferred iron in accordance with the present invention; Fig. 2 is a side view of a preferred club 20 head in accordance with the present invention; Fig. 3 is a front view of a preferred club head in accordance with the present invention; Fig. 4 is a bottom view of a preferred club head in accordance with the present invention; 25 Fig. 5 is a back view of a club head as embodied in a 2 iron; Fig. 6 is a section view of Fig. 5 of a club head as embodied in a 2 iron; Fig. 7 is a back view of a club head as embodied in an 8 iron; Fig. 8 is a section view of Fig. 7 of a club head as embodied in an 8 iron; Fig. 9 is a back view of a club head as embodied in a pitching wedge; and Fig. 10 is a section view of Fig. 9 of a club 10 head as embodied in a pitching wedge.

Fig. 1 illustrates iron 10. Iron 10 comprises shaft 12 with grip 14 and head 16. Head 16 is connected by hosel 18 to shaft 12 in conventional manner. Similarly, grip 14 is attached to shaft 15 12 in conventional manner. Head 16 comprises toe 20, heel 22, sole 24 and top 26. Finished club height 28 is also illustrated. Finished club height 28 progressively decreases from long irons to short irons as is conventional. Front face 32 is suitably 20 scored with grooves in conventional manner.

Fig. 2 illustrates a side view of a club head. Loft angle 30 is the angle between the center line of the hosel 18 and the club head face 32. Top line thickness 34 is the thickness of the top of 25 the club head from the face to the back of the club head. Preferably, top line thickness is uniform across the top of the club head for each of the 242859 clubs. Offset 36 is the parallel distance from the plane 37 tangent to the front of hosel 18 to the leading edge 39 of face 32. Preferably, the offset progressively decreases from the long irons to the short irons. Bounce angle 38 is also depicted. It is also preferred that the bounce angle increases from long irons to short irons.

Fig. 3 illustrates the front of a club head which has not been scored. Lie angle 40 is shown, along with hosel length 42, par height 44, toe height 46, and blade length 48. Mid-point 50 of blade length 48 is also shown. Although not necessarily to scale, the location of the geometric center of the club head face is shown as 52. The geometric center is about a golf ball's radius up from sole 24. Preferably, geometric center 52 is about 1.0 to about 0.5 inches (2.5 to 1.3 cm) measured vertically from sole 24 with the hosel held in a vertical plane as shown in Figures 5 to 10. More preferably, it is about 0.9 inches (2.3 cm) from sole 24.

Fig. 4 illustrates sole 24 of a club head with heel sole width 60 and toe sole width 62.

Cavity 70 is shown in the back of the club head.

Fig. 5 illustrates the cavity back of a number 5 iron, while Fig. 7 illustrates the cavity back of a number 8 iron, and Fig. 9 illustrates the cavity back of a pitching wedge (PW). Figs. 6, 8 and 10 are side views of the respective irons illustrated in Figs. 5, 7 and 9 along the center lines as shown. In each of Figs. 5-10, cavity 70 is illustrated. The longest dimension 72 of the cavity is also shown.

For a preferred set of irons made in accordance with the present invention, the following dimensions are provided ; TABLE A-l Elements (30) (40) (36) (38) (42) ( 48 ) Loft Lie Bounce Hosel Blade Angle Angle Offset Angle Length Length Iron (deg) (deg) (in) (deg) (in) (in) 1 16 56 . 386 -3 2.65 3.0 2 18 57 . 363 -3 2.67 3.0 3 21 58 .330 -2 2. 66 3.0 4 24.5 59 .293 -2 2.67 3.0 28 60 .257 -1 2. 67 3.0 6 32 61 .218 -1 2. 72 3.0 7 36 61.5 .181 0 2.72 3.0 8 40 62 .144 + 1 2.70 3.0 9 44 62.5 .109 + 2 2.70 3.0 PW 48 63 .095 + 4 2. 75 3.0 W 52 63 .095 + 4 2.75 3.0 sw 56 63 + .010 + 10 2.72 3.0 LW 60 63 + .010 + 8 2.70 3.0 242859 TABLE A-2 Elements (34) (62) (60) (28 ) Toe Heel Top Line Sole Sole Head Finished Thickness Width Width Weight Club Length Iron ( in) (in) ( in) (gram) (in) 1 0.27 .885 . 590 235 39 . 5 2 0.27 .910 . 605 242 39 3 0.27 .910 . 605 247 38.5 4 0 .27 .920 . 640 253 38 0.27 .925 . 640 260 37.5 6 0.27 .925 . 650 267 37 7 0 .27 .940 . 680 274 36.5 8 0.27 .940 . 680 282 36 9 0.27 .990 .695 286 .625 PW 0.27 1.040 . 725 289 .5 W 0.27 1.040 .730 293 .5 SW 0.27 1.060 .810 292 .5 LW 0.27 1.060 .800 291 . 5 TABLE A-3 Elements (72) Cavity % Club Weight in Iron Volume (in J) Combined Toe and Sole 1 0.6 50 • 2 0.65 52 3 0.55 50 4 0.58 52 0.28 53 6 0.44 56 7 0.4 56 8 0.47 57 9 0.35 57 PW 0.35 57 W — 57 SW 0.32 57 LW — 57 The toe and sole weight were measured by physically cutting each club along the line marked 71 in Fig. 5. The line 71 is a continuation of the toe line and the sole line of each cavity 70. The cavity volume 5 was measured by placing each club with the back horizontal, filling the cavity with sand, levelling the sand to be even with the back of the club head, measuring the weight of the sand and calculating the volume from the measured weight.

The irons can be made of any desired metal.

Best results have been obtained using stainless steel that has been heat treated to obtain a Rockwell hardness of C18-C22.

Any conventional shaft and grip can be used 15 with the club heads of the present invention.

Best results have been obtained with True Temper shaft MS-209 and Golf Pride Victory half cord grip.

It will be understood that the claims are intended to cover all changes and modifications 20 of the preferred embodiment of the invention herein chosen for the purpose of illustration which do not constitute a departure from the invention.

E N jT Gh i'v .2 r-.J \ "4A

Claims

i 1 A 7 F £cm JL» L What we claim is:

1. A set of irons each of which has a club head, and a shaft, each said club head having a front playing face and a back, said back having a cavity therein, said front playing face having a geometric center as hereinbefore defined and the perimeter weighting of the club head outside the cavity being adjusted such that each said club head has a center of mass which coincides with said geometric center of said playing face.

2. The set of irons of claim 1 wherein each club head has an offset as hereinbefore defined and said offset progressively decreases from long irons to short irons.

3. The set of irons of claim 1 wherein there are included long irons, medium irons and short irons and wherein the long irons have a negative bounce angle, the medium irons have a neutral bounce angle, and the short irons have a positve bounce angle.

4. The set of irons of claim 1 wherein said cavity has a volume and said volume is greater in the long irons than in the short irons. r 10 7 A ? Q R <&» ^

5. The set of irons of claim 1 wherein said club head has a hosel length and said hosel length remains substantially constant.

6. The set of irons of claim 1 wherein said club head has an overall weight, a sole weight and a toe weight as hereinbefore defined and the ratio of combined toe weight and sole weight to said overall weight is greater in the short irons than in the long irons.

7. A set of irons having a plurality of irons within said set, each iron within said set comprising a club head and a shaft; each club head comprising a hosel for attachment of said club head to said shaft, the hosel length being substantially the same for each club head in the said set, a face for striking a golf ball, and a back having a cavity therein; each iron within said set having a geometric center of said face of said club head as hereinbefore defined and a center of mass of said club head; each of said irons within said set having said cavity within said back varyinq in volume, with long irons having a greater volume than short irons and the perimeter weighting of each club head outside the cavity being such that said geometric center coincides with said center of mass for each of said irons in said set. -11-

8. The set of irons of claim 7 wherein each iron within said set has substantially identical hosel lengths.

9. A set of irons substantially as hereinbefore described with reference to any of the accompanying drawings. -12-