GB2295326A

GB2295326A - Golf CLUB HEAD

Info

Publication number: GB2295326A
Application number: GB9423557A
Authority: GB
Inventors: Fergus Johnathan Ardern
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-11-22
Filing date: 1994-11-22
Publication date: 1996-05-29
Also published as: GB9423557D0

Abstract

A golf club head which, in vertical cross section at its intended ball-centre-striking plane, (1) contains a convex ball-striking curve B, (2) below that curve is either substantially flat or contains a curvature which extends that of the top-half ball-striking curve B, and (3) the curved part of the face defines less than a complete semi-circle and is other than semi-circular in profile. <IMAGE>

Description

GOLF CLUB HEAD Field Of The Invention The invention relates to golf club heads, and to golf clubs incorporating such heads, and is particularly applicable to putter heads and putters.

Review Of Art Currently Known To The Applicant The design of golf club heads varies enormously and very many proposals have previously been put forward. The weighting, shaping, balance and proportioning of the head have all receive diverse attention in the past. In particular the design of golf putters is forever trying to be improved because putting is one aspect of the game that can make a crucial difference between winning and losing, and when a golfer loses his confidence in this area, it can notoriously take a long time to regain.

Conventional putters have a substantially flat ball-striking face. They may incorporate relatively elaborate shaping and weighting profiles over the putter head as a whole, as shown for example in United States patent number 4 527 799 (Solheim) which describes and illustrates the well-known PING putter head. But even such a relatively complex head design as this one does not show anything other than an essentially flat ball-striking face. The design effort is concentrated in other areas of the head.

A more advanced state of the art design is the so-called RHOLER putter which is currently marketed in the United Kingdom by Rholer Sports Products Limited of Bideford, Devon, UK This consists of an essentially circular-cylindrical head which, when swung into contact with the golf ball, is said to roll the ball forward from the outset of the contact and hence to prevent any initial tendency of the ball to skid off the putter face. With putting, as is self-evident, the essence of success is control rather than length of shot. And any initial skidding movement of the ball off the putter face, however short-lived, will undermine the directional control that the golfer seeks to exert.

The RHOLER putter has had some commercial success but in the view of the present applicant it still has drawbacks. Chief amongst these is an inevitable tendency to yaw, as the head is swung into contact with the ball, and this tendency will be exacerbated at the moment the head does strike the ball, because of the way the head is shaped as a circular cylinder throughout its entire length. It will also be made worse by the way the head is fixed to, and balanced overall as part of, the club shaft in the current commercial RHOLER designs. But the yawing tendency is an inherent function of the head design irrespective of where the head is balanced in relation to the shaft.

The present invention takes the RHOLER design as its starting point and seeks to incorporates its ball-striking advantages whilst overcoming this inherent drawback.

Summarv Of The Invention According to the invention in its broadest aspect, a golf club head, when stood upright and viewed in cross-section at its intended ball-centre-striking plane, is characterised by the features that the top half of the ball-contacting face contains a convex ball-striking curve; that the rest of the face, below that curve, is either substantially flat or contains a curvature which extends that of the top-half ball-striking curve; and that the curved part of the face defines less than, a complete semi-circle and is other than semi-circular in profile.

Such a face profile will tend to the virtual elimination of an initial skid of the ball off the face as the ball is struck by the head, even if the club is lofted as is commonly the case, whilst giving a much better balanced feel to the head than the constant-radius circular-cylindrical RHOLER design.

The top-half ball-striking curve may be a convex curve of substantially constant radius and in such a case the radius of this curve preferably occupies the range of from 2.5 to 2.75 times the height of the face at its intended ballcentre-striking plane; and is preferably approximately 2.6 times the said height.

The head, again when stood upright and viewed in cross-section at its central ball-striking plane, may be substantially symmetrical about a notional upright centre line. Club heads are by no means necessarily symmetrical, as the previously mentioned PING patented design illustrates very well. It is therefore a non-evident feature to make the present invention of symmetrical aspect and it has been found that, with the broad-aspect inventive feature in place, the head is maximally balanced and effective if a symmetrical design is adopted.

The invention includes within its scope a golf club head, in particular a putter head, substantially as described herein with reference to and as illustrated in any appropriate combination of the accompanying drawings.

The invention also includes within its scope a golf club, in particular a putter, incorporating a head in accordance with any of the preceding aspects defined as embodying the invention. In this particular context it is advantageous, and again non-evident, to join the club shaft to the head such that the acute angle defined between them lies within the range of from approximately 65" to 75" and, particularly advantageously, is approximately 70". This range, and this particular approximate angle, respectively, are thought currently to give best balance and feel to the head-shaft club combination when a head embodying the invention is incorporated into a putter.

Reference was made earlier to the difficulties with the RHOLER design being exacerbated by the way the shaft joins the head in the commercially available forms of that design. The RHOLER club shaft enters the head at one end of the circular-cylindrical head. Although the shaft is actually fixed to the other end of the cylinder, this one-end-located feature does tend to unbalance the head and promote the yawing disadvantage outlined above.

In a further advantageous development of the present invention, therefore, and when the invention is embodied in a club comprising a head and a shaft, preferably the shaft enters the head in the region of the ball-striking plane and such that, when the head is stood upright, and viewed face-onwards, the shaft - or a notional projection of the shaft boundaries - is disposed approximately symmetrically about a notional horizontal plane passing through the intended ball-striking spot.

In the case just outlined, preferably the shaft does physically continue down into the head rather than terminating at its juncture with the head surface, again for reasons of better overall balance and feel.

Brief Description Of The Accompanying Drawings In the drawings: Figure 1 shows the club head region of a putter embodying the invention, drawn in perspective; Figure 2 shows the club head region in cross-section when the head is stood upright and viewed on the central ball-striking plane; Figure 2A shows a modification of Figure 2; Figure 3 shows the club head region, again with the head stood upright but this time viewed face-on; and Figures 4 and 5 show respectively modified versions of the club head, each viewed face-on.

Description Of The Preferred Embodiments The illustrated putter comprises a shaft S and head H, the shaft being elongate, straight, formed of suitably solid circular-cylindrical metal and terminating in a grip region (not shown) none of which is crucial to the present invention and can be settled by the intended skilled addressee of this specification.

The shaft S enters the head H at an acute angle of between 68" and 72", i.e approximately 20 in this instance.

To join the shaft to the head, the head is drilled, in this instance to within 1 millimetre of its foot F. The drill hole does not go all the way through the head, although it could do, with or without any subsequent filling-in because the shaft as will be seen stops 1 millimetre short of the foot F of the head.

As Figure 3 shows, the shaft enters the head approximately at the mid-length plane P1 of the head. The intended optimum ball-striking spot of the ballstriking face B of the head is, again as shown in Figure 3, the intersection of this plane P1 with a horizontal plane P2 (which is horizontal when the head is stood upright and viewed face-on as in Figure 3) which runs along the head at the level where a standard-diameter golf ball would ideally contact the ballstriking face B of the head if the club were swung to address the ball with the club foot F brushing the ground at the moment of contact with the ball.

The length L of the head H is 110 millimetres. The radius R from which its continuously curved foot F is struck is 150 millimetres. The top surface T of the head H is parallel with the bottom foot surface F when viewed as in Figure 2 and the circular solid shaft S is 10 millimetres in diameter.

Each opposite end face E of the head H extends down from the top surface T of the head at right angles and is 8 millimetres long to the point at which it intersects the curve of the foot F of the head.

Referring now to Figure 2 in particular, the overall height referenced 11 of the head is 21 millimetres. Within the top half of this height 11 the ballstriking face B describes a constant-radius curve which extends from the top surface T of the head for a distance D of 11 millimetres. The radius reference 14 of this curve is 54 millimetres. The width referenced 13 of the top surface T of the head is 18 millimetres. The width 12 of the bottom foot surface F of the head is 21 millimetres.

The remaining 10 millimetre depth of the head H is substantially flat. But in this particular embodiment it is not precisely vertical when viewed as in Figure 2. Instead, as will be seen, the flat section of the ball-striking face B in this 10 millimetre drop from the end of the 54 millimetre radius curve depth D is angled very slightly outwards by an angle A of approximately 2" from the notional vertical.

The head H is symmetrical about the plane P1 when viewed as in Figure 2 and the shaft, when similarly so viewed, is symmetrically distributed about the P1 plane as well.

In use with a standard sized golf ball whose diameter is just over 42 millimetres the ball-contacting plane P2 will, when the club is ideally swung, strike the ball just below the mid-height plane of the ball. The curved section of the ball-striking face will tend to roll the ball off the putter face B without any inherent tendency for the ball initially to skid. The particular shape and symmetry of the head illustrated gives an optimum balance and feel to the putter in use.

InFigure 4 the end faces E of the head do not extend down at right angles to the top surface T but form an angle to it. The reflex angle is approximately 135". In Figure 4 each end face E is a flat face like the flat face of the Figure 1 and Figure 3 embodiment. In Figure 5 it is a symmetrical V-shaped face.

In Figure 2A, the curved top half and substantially bottom part of the face B are replaced by a single top-to-bottom constant-radius curve of approximately 54 millimetres; and this would be repeated as a mirror-image for the back (not shown in this Figure) of the club head. As with the Figure 2 embodiment, this curve is struck from a notional horizontal line 11 millimetres down from the top surface T of the club head (i.e 10 millimetres up from the foot F) at the head's mid-plane.

Claims

1. A golf club head which in cross-section at its intended ball-centre-striking plane is characterised in that: - the top half of the ball-contacting face contains a convex ball-striking curve - the rest of the face below that curve is either substantially flat or contains a curvature which extends that of the top half ball-striking curve; and - the curved part of the face defines less than a complete semi-circle and is other than semi-circular in profile.

2. A golf club head as claimed in claim 1 in which the top half ball-striking curve is a convex curve of a substantially constant radius in the range of from 2.5 to 2.75 times the height of the face at its intended ball-centre-striking plane.

3. A golf dub head as daimed in daim 2, in which the radius of the curve is approximately 2.6 times the said height.

4. A golf dub head as claimed in any of the preceding claims, which is substantially symmetrical about 8 notional upright centre line.

5. A golf club head, in particular a putter head, substantially as described herein with reference to and as illustrated in any appropriate combination of the accompanying drawings.

6. A golf dub incorporating a golf dub head as daimed in any of the preceding daims.

7. A golf dub as claimed in daim 6, in the form of a putter.

8. A golf club as daimed in daim 6 or daim 7, in which the dub shaft is joined to the head in such a manner that the acute angle defined between them lies within the range of from approximately 65 degrees to 75 degrees.

9. A golf club as daimed in daim 8, in which that acute angle is approximately 70 degrees.

10. A golf dub as daimed in any of daims 6 to 9, in which the shaft enters the head in the region of the ball-striking plane and (when the head is stood upright, and viewed faceonwards ) the shaft or a notional projection of the shaft boundaries is disposed approximately symmetrically about a notional horizontal plane passing through the intended ball-striking spot.

11. A golf club as claimed in any of claims 6 to 10, and substantially as herein described and shown in the accompanying drawings.

11. A golf club as claimed in any of daims 6 to 10, in which the shaft physically continues down into the head rather than terminating at its juncture with the head surface.

12. A golf club as claimed in any of claims 6 to 11, and substantially as herein described and shown in either of figures 1 and 3 of the accompanying drawings.

Amendments to the claims have been filed as follows 1. A golf club head in which the ball-contacting face in cross-section at its intended ball-centre-striking plane is a convex ball-striking curve of a substantially constant radius less than a complete semi-circle.

2. A golf club head as claimed in claim 1 in which the convex ball-striking curve has a radius in the range of from 2.5 to 2.75 times the overall height of the face in its intended ball-centre-striking plane.

3. A golf club head as claimed in claim 2, in which the radius of the convex curve is approximately 2.6 times the said height.

4. A golf club head as claimed in any of the preceding claims, which is substantially symmetrical about a notional upright centre line.

5. A golf putter head substantially as described herein with reference to and as illustrated in the accompanying drawings.

6. A golf club incorporating a putter head as claimed in any of the preceding claims.

7. A golf club as claimed in claim 6, in which the club shaft is joined to the head in an inclined manner such than the acute angle defined between them lies within the range of from approximately 650 to 750.

8. A golf club as claimed in claim 7, in which that acute angle is approximately 700.

9. A golf club as claimed in any of claims 6 to 8, in which the shaft enters the head in the region of the ballstriking plane and (when the head is stood upright, and viewed face-onwards) the shaft or a notional projection of the shaft boundaries is disposed approximately symmetrically about a notional horizontal plane passing through the intended ball-striking spot.

10. A golf club as claimed in any of claims 6 to 9, in which the shaft physically continues down into the head rather than terminating at its juncture with the head surface.