WO1994015677A1

WO1994015677A1 - Golf club head with striking face covered with a material having different modulus

Info

Publication number: WO1994015677A1
Application number: PCT/FR1993/001288
Authority: WO
Inventors: Benoît VINCENT; Jean-Pierre Rigal
Original assignee: Taylor Made Golf Company, Inc.
Priority date: 1993-01-15
Filing date: 1993-12-22
Publication date: 1994-07-21
Also published as: FR2700475A1

Abstract

The invention relates to a golf club head comprising a body (1) and an impact face (2) limited by an upper edge (20), a lower edge (21) and two side edges (22, 23); in the center of the face (2) is fictively defined the impact center (O) which is the origin of a fictive orthogonal mark defined by a horizontal axis (I, I') and a vertical axis (J, J'); the intersection of the axis (I, I') with the side edges (22, 23) define the width (L) of the face (2) and the intersection of the axis (J, J') with the lower (21) and upper (20) edges define the height (H) of the face. The impact face (2) is divided into two distinct surfaces (S1) and (S2); the surface (S1) is covered with a material having a high Young modulus, higher than 15 GPa, preferably higher than 100 GPa; said surface extends horizontally on either side of (I, I') throughout a width (l) comprised between 20 and 40 % of (L); and vertically from the lower edge (21) up to beyond the axis (I, I') throughout a height (h) comprised between 65 and 85 % of (H); the surface (S2) is covered with a low Young modulus material, lower than 15 GPa, preferably comprised between 0.1 and 10 GPa; said surface (S2) extends on the remainder of the face.

Description

Club head with striking face covered with a material of different modules.

The present invention relates to a golf club head. It relates more particularly to an improvement concerning its striking face.

The striking faces of current golf clubs are generally made from materials with a high modulus of elasticity for various reasons. On the one hand, the impact face must resist the impact of the bullet and not collapse. On the other hand, the modulus of the material influences the starting speed of the ball. When the module is too low (below 0.1 GPa) the speed drops considerably. In addition, the Applicant has found that the high modules tend to provide less "retro" effect to the ball (called "back spin"). The association of the two components; high speed and low back spin rate; has the effect of increasing the distance traveled by the ball. The materials used are generally metals (steel, aluminum or others), ceramics or composite materials based on epoxy resin loaded with carbon fibers, for example.

The Applicant has nonetheless found that these types of face were not very tolerant during off-center hits on the lateral parts of the face. In other words, the meshing effect is weak so the rotation of the ball also ("side spin") and leads to a significant dispersion of the balls on arrival. For heads of the "wood" type, the graining effect can be partly corrected by the horizontal curvature of the face (called "bulge"), but this solution is still not satisfactory because it is difficult to control and industrially respect this geometrical parameter on the heads "wood metal" in particular. In addition, the heads of the type "iron" are generally flat and the correction by the "bulge" is not possible.

Finally, during strikes on the upper part of the face, that is to say above the center of percussion of the face, the "retro" effect (back spin) is considerably reduced. The use of high modulus materials leads to reducing the "retro" effect in a proportion such that the ball no longer flies correctly and the flight distance is greatly shortened.

Conversely, document FR-A-2 550 457 describes a golf club head comprising a front plate constituting part or all of the front impact face and produced in an ionomer resin including the Young's compression module is weak ; on the order of 0.2 to 0.5 GPa. This document aims to demonstrate that the use of ionomers in the defined value range allows a gain in bullet speed (or coefficient of restitution) compared to steels, for example. The gain is in fact low and of the order of 0.5 to 1 m / s approximately. On the other hand, the values of "back spin" with this type of material are large and tend to brake the ball when it comes into contact with the ground. Ultimately, the gain in distance traveled by the ball is zero, or even negative, compared to the use of steels.

The present invention aims to improve the known heads and provide the best distance / tolerance compromise regardless of where the impact is made on the face.

To this end, the golf club head according to the invention comprises a body and an impact face bounded by a lower edge, an upper edge and two lateral edges; in the center of the face is fictitiously defined the center of percussion (O) which is at the origin of a fictitious orthogonal coordinate system defined by a horizontal axis (I, r) and a vertical axis (J, J '); the intersection of the axis (I, r) with the lateral edges define the width (L) of the face and the intersection of the axis (J, r) with the lower and upper edges define the height (H) of the face. The impact face is divided into two distinct surfaces (S1) and (S2);

- the surface (S1) is covered with a material with a high Young's modulus; greater than 15 GPa; preferably greater than 100 GPa and said surface (S1) extends horizontally on either side of the axis (J, J ') over a width (I) between 20 and 40% of the width (L) , and vertically, from the vicinity of the lower edge, to beyond the axis (I, r) over a height (h) between 65 and 85% of (H);

- the surface (S2) is covered with a material with a low Young's modulus; less than 15 GPa, preferably between 0.1 and 10 GPa; said surface (S2) extending over substantially the remaining surface of the impact face.

Advantageously, the material of the surface (S1) is chosen from metallic materials; such as aluminum, titanium, steel, bronze and tungsten. It can also be chosen from; high modulus rubber, ceramics, composite materials with thermosetting matrix loaded with fibers and composite materials with high modulus thermoplastic matrix highly charged with fibers.

The surface material (S2) is chosen from thermoplastics based on polyamides, ABS, Polyethylenes, ionomers and derivatives. The invention will be better understood on reading the following detailed description and with reference to the accompanying drawings which show by way of examples particular modes of the invention:

- Figure 1 is a front view of a golf club head according to the invention;

- Figure 2 is a perspective view of the head of Figure 1;

- Figure 3 is a sectional view along (A, A ') of the head of Figure

1;

- Figures 4 and 5 illustrate two comparative graphs during off-center firing on the tip side ("toe") with a traditional head (Figure 4) and a head according to the invention (Figure 5);

- Figure 6 is a view of a particular assembly of a head according to an embodiment of the invention;

- Figure 7 is a view of a variant of Figure 6;

- Figure 8 is another variant;

- Figure 9 is a view of a head of the "iron" type.

The head according to the invention, as illustrated without limitation in FIG. 1, can be of the "wood" type and comprises a body (1) comprising an impact face (2) and extends laterally and towards the high by a neck (3) intended to receive the club handle. The impact face is limited by an upper edge (20), lower edge (21) and two lateral edges (22, 23). The center of the face, also called the percussion center, is fictitiously represented by the point (O). It defines the origin of a fictitious orthogonal coordinate system consisting of a horizontal axis (I, r), parallel to the ground, and a vertical axis (J, J ') perpendicular to (I, I') - The surface and the shape of the impact face generally vary appreciably from one head to another and it is therefore difficult to define benchmarks comparable from one head to another. This is why, in the present case, it is considered that the width (L) of the head corresponds to the distance of the points of intersection of the lateral edges (22, 23) with the axis (I, r). Similarly, the height (H) corresponds to the distance from the points of intersection of the upper (20, 21) and lower edges with the axis (J, J ').

Thus identified, the face (2) according to the invention is divided into two distinct surfaces (S1) and (S2). The first surface (S1) extends on the one hand in a horizontal direction on either side of the axis (J, J '), symmetrically over a width (I) of between 20 and 40% of the width (L) of the face defined above. This first surface (S1) extends on the other hand, in a vertical direction, from the vicinity from the lower edge (21) to beyond the axis (I, r) over a height between 65 and 85% of the height (H) of the face.

The surface (S1) is made of a material with a high Young modulus. According to the invention, the module is greater than 15 GPa, preferably greater than 100 GPa.

In Figure 1, there is illustrated in a dotted circle (C), the impact limit of a ball around the center (O), for a perfectly centered shot. The circle (C) has a diameter of about 18 (± 1 mm) and fits entirely into the surface (S1). In other words, for centered shots, the bullet comes into contact with a high modulus material only. So the ball speed is excellent; the "back spin" effect is weak but sufficient to allow the ball to fly properly. The speed / back spin compromise is therefore perfectly optimized to obtain a maximum distance.

The circle (C1) represents the impact limit of the ball during an off-center hit at the bottom of the face. In this case, the ball undergoes no lateral deflection; on the other hand, the retrograde rotation of the ball ("back spin") is more important at this point than at the center face (O). (C1) fits entirely into the surface (S1) of material with high Young modulus; the back spin is considerably limited and the distance traveled by the ball is thus increased.

Among the materials which may be suitable for (S1), one can choose metallic materials such as aluminum (70 GPa), titanium (100-150 GPa), steel (170-210 GPa), bronze (60 GPa), tungsten (400 GPa). It is also possible to use certain high modulus rubbers (75 GPa), ceramics (600 GPa), composite materials with thermosetting matrix such as epoxy or other charged with carbon fibers, glass, metals or others (graphite ≡100 GPa), and certain composite materials with a high modulus thermoplastic matrix loaded with glass fibers (20 GPa).

The second surface (S2) extends over substantially the entire remaining surface of the impact face. In other words, it occupies the lateral regions of the face as well as the upper region. The surface (S2) is made of a material with a low Young's modulus. According to the characteristic of the invention, the module is less than 15 GPa, preferably between 0.1 and 10 GPa. Below 0.1 GPa, the Applicant has found that the speed of the ball drops to values less than 50 m / s; whereas the values reached beyond are of the order of 60-70 m / s for a head speed between 40 m / s and 50 m / s. During off-center shots on the heel side ("heel") or toe side ("toe"), the impact of the bullet is inscribed, at least in part, in the surface (S2) with low Young modulus, thus providing a strong side spin effect on the ball, which has the positive effect of refocusing the ball in relation to an ideal rectilinear trajectory.

Figures 4 and 5 show a comparative test for 10 off-center "toe" shots 20 mm from the center face (O). The scale on the abscissa is the relative lateral deviation in meters relative to a rectilinear trajectory identified at point (O). The ordinate scale is the distance traveled by the ball in meters.

FIG. 4 relates to a head whose surface (S2) is made of steel, therefore with a high modulus. FIG. 5 relates to a head whose surface (S2) is made of plastic material with a low Young's modulus.

During shots off-center at the top, the impact of the bullet is at least partly inscribed in the surface (S2). Due to the low modulus of the material, the back spin effect is increased to a value sufficient to allow the ball to fly properly. As mentioned above, below a given "back spin" rate, the ball distance drops sharply, hence the need to ensure a minimum "back spin" value in this region.

Among the materials that can be used to cover the surface (S2), there may be mentioned thermoplastics without load (0.1-2 GPa), such as polyamides, ABS, polyethylenes, ionomers and derivatives. Mention may also be made of plastic materials loaded with fibers (1 -15 GPa).

As shown in the example of FIG. 3, the body (1) of the head comprises a hollow shell which may be metallic or made of any other resistant material such as composite or injected plastic.

The shell includes an upper (10), lower (11) wall, a peripheral wall (12) and a front wall (13). These different walls form a closed internal cavity (4) advantageously filled with a foam, such as a polyurethane foam. On the front wall (13) is provided a housing (130) in which is fitted an insert (6) in two parts (60, 61) of materials with different Young's modulus. Both parts can be brought back at the same time or separately in the accommodation. Preferably, the housing (130) has substantially a height close to the height (H) of the impact face. In particular, the edge (131) of the housing has a small thickness (e) of the order of only 1-2 mm. FIG. 6 illustrates a particular embodiment of a "wood" type head provided with a housing (130) whose shape is complementary to that of an attached part (6). The part (6) comprises two parts (60, 61); a part (60) of material with high Young modulus, corresponding to the impact surface (S1) and a second part of material with low modulus (61) corresponding to the surface (S2). The part (6) can be fixed in the housing by any suitable means such as gluing, screwing, riveting or the like.

FIG. 7 illustrates a variant in which the housing (130) of the body (1) is limited to the surface (S2). The insert (61) has a shape complementary to that of the housing and is therefore made of the same material with a low Young's modulus. The body (1) comprises a front part (131) in relief, corresponding to the surface (S1). Its surface reaches flush with the surface of the insert (61). Advantageously, the body (1) is made of metal such as steel, titanium or aluminum by molding. The insert (6) can be made of plastic separately and then glued and / or screwed inside the housing.

FIG. 8 illustrates another variant according to which, the housing is limited to the surface (S1) only and receives an insert (60) of complementary shape made of material with a high modulus. The body (1) is made of plastic material loaded or not with low modulus. Advantageously, it is obtained by injection.

FIG. 9 illustrates an exemplary embodiment of the invention for a head of the "iron" type. The particular shape of the surface (S1) is not limited. Advantageously, it is trapezoidal in shape, the large base of which is located in the vicinity of the lower edge (21) of the face. However, other forms can be provided without departing from the scope of the invention.

Claims

1) Golf club head comprising a body (1) and an impact face (2) bounded by an upper edge (20), lower edge (21) and two lateral edges (22, 23); in the center of the face is fictitiously defined the center of percussion (O) which is the origin of a fictitious orthogonal coordinate system defined by a horizontal axis (I, r) and a vertical axis (J, J '); the intersection of the axis (I, r) with the lateral edges (22, 23) define the width (L) of the face and the intersection of the axis (J, P) with the lower edges (21) and upper (20) define the height (H) of the face; characterized in that said impact face (2) is divided into two distinct surfaces (S1) and (S2):

the surface (S1) being covered with a material with a high Young's modulus, greater than 15 GPa, preferably greater than 100 GPa; said surface (S1), extending horizontally on either side of the axis (I, r) over a width (I) of between 20 and 40% of (L); and vertically from the lower edge (21), beyond the axis (I, r) over a height (h) of between 65 and 85% of (H);

the surface (S2) being covered with a material with a low Young's modulus, less than 15 GPa, preferably between 0.1 and 10 GPa; said surface (S2) extending over the rest of the face.

2) Golf club head according to claim 1, characterized in that the material of the surface (S1) is chosen from metallic materials, such as aluminum, titanium, bronze, steel and tungsten.

3) Club head according to claim 1, characterized in that the surface material (S1) is chosen from high modulus rubber, ceramic, composite materials with thermosetting matrix loaded with fibers, and composite materials with matrix high modulus thermoplastic with high fiber content.

4) Club head according to claim 1, 2, or 3, characterized in that the surface material (S2) is chosen from thermoplastic materials based on polyamides, ABS, polyethylenes, ionomers and derivatives.

5) Club head according to claim 4, characterized in that the plastic materials are loaded with short fibers.

6) Club head according to any one of the preceding claims, characterized in that the body (1) is provided with a housing (130) in which is inserted an insert (6) in two parts (60, 61) corresponding to the two distinct surfaces (S1) and (S2). 7) Club head according to any one of claims 1 to 5, characterized in that the body (1) is provided with a housing (130) limited to the surface (S2) and receives an insert (61) of complementary form; said body comprising a front part (131) in relief corresponding to the surface (S1).

8) Club head according to any one of claims 1 to 5, characterized in that the body (1) is provided with a housing (130) limited to the surface (S1) only and receives an insert (60) of complementary shape.

9) Club head according to any one of the preceding claims, characterized in that the shape of the surface (S1) is trapezoidal, the large base of which is located in the vicinity of the lower edge (21).

10) Golf club head according to any one of the preceding claims, characterized in that it is a head of the "wood" type.

11) Golf club head according to any one of the preceding claims, characterized in that it is a head of the "iron" type.