FR2717701A1 - Head of golf club with shock absorber - Google Patents

Abstract

The head (3) of the golf club has a front hitting surface (5) and a sole (6) which extends backwards. A shock absorber (10) is fixed to the inner surface of the back part of the sole (5). It has an annular rigid plate (11) with is fixed to the surface by a layer of visco-elastic material (12). The plate has a Young's modulus which is greater than 10,000 Mpa and its thickness is less than 1 mm. Its coefficient of absorption is between 0.4 and 1.2. The plate is held in a cavity (7) in the surface.

Description

IMPROVED GOLF CLUB HEAD
Technical area
An improved golf club head is provided; it relates in particular to golf irons equipped with such a head.

Prior art
As is known, a golf club head called "iron" is either forged or molded, and is intended to be connected to a handle. This head has at the front a flat striking face, below a sole which extends on the bottom and towards the rear of the striking face, and a rear face arranged at the back of the striking face. According to the manufacturers, according to the desired results, and according to the manufacturing techniques used, this rear face can have the most diverse shapes. Increasingly, this rear face is hollowed out and has a cavity.

 In document WO 93/20 904, the Applicant has described a golf club head, in which the rear face also has a shock absorber assembly consisting of a stress plate connected to the rear face by a layer of viscoelastic material . In this way, the vibrations caused during the impact of the bullet are greatly attenuated. In addition to improving the technical characteristics of the club in terms of comfort and precision, this device reduces the phenomena of resonance. Such clubs are moreover successfully marketed under the name "VAS 792".

Statement of the invention
The invention is an improvement in clubs of the type in question.

 According to the invention, the characteristic damping element follows a generally annular shape.

 In other words, the invention is distinguished from the state of the art by the fact that the damping element is no longer full, but marries a peripheral annular shape, which allows not only to obtain the effect sought to attenuate vibrations and improve sensations, but also to improve the peripheral distribution of the weight of the club head, which is always sought to obtain better impact tolerance, especially with average players or less experienced.

Advantageously, in practice
- As already said in the document WO 93/20 904 of the Applicant cited in the preamble, the stress plate is an annular rigid plate having a Young's modulus greater than 10,000 MPa and a thickness of between 0.07 and 2.0 mm, and the layer of viscoelastic material has a thickness of less than 3 mm and has an intrinsic damping coefficient (tangent delta) of between 0.4 and 1.2
the rear face has a cavity disposed above the sole and the bottom of which is parallel to the striking face, the characteristic annular damping element then being placed in this cavity, the edge of which it follows
- The ratio between the surface of the characteristic annular damping element and the hollow center of this annular element is between 0.1 and 0.9, preferably around 0.5;
- The stress plate is flat and the viscoelastic layer has a uniform thickness;
- the stress plate is concave or convex.

 In an alternative embodiment, the viscoelastic sheet can be constituted by a stack of several elementary viscoelastic sheets, with different characteristics. The damping properties of each of them are offset in temperature for a given vibration frequency, or are offset in frequency for a given temperature.

 According to another variant, the visco-elastic sheet is constituted by a juxtaposition in the main plane of elementary zones each having optimal damping properties, also shifted in frequency and in temperature.

 As already said, the invention also relates to so-called "iron" golf clubs, the head of which is equipped with such an annular damping element.

 The manner in which the invention can be implemented and the advantages which ensue therefrom will emerge more clearly from the embodiment which follows, supported by the appended figures.

Brief description of the drawings
FIG. 1 is a summary perspective view of a golf club called "iron", the head of which is shown in rear view in FIG. 2.

 FIG. 3 is a head according to the invention also shown in rear view and FIG. 4 is a section along the axis IV-IV 'of FIG. 3.

 FIG. 5 is a detailed sectional view of the vibration damper assembly characteristic of the invention, shown in summary perspective in FIG. 6.

 Figures 7 to 10 schematically illustrate alternative embodiments of the invention.

 Referring to Figures 1 to 6, a traditional golf iron (molded iron) according to the invention comprises a handle (1), for example of metal or reinforced plastic, terminated at its upper free end by a handle ( 2), and connected at its other lower end by means of a fitting (4) to a head designated by the general reference (3), the weight and shape of which vary according to the number of the iron. This head (3) which has an approximate section in the shape of an L, comprises respectively on the front, constituting the large branch of the L, a wall of five millimeters thick having an external planar striking face, designated by the reference (5 ), striated, and a sole (6), forming the small branch of the L. In known manner, the head (3) has on the rear a recess (7) forming a cavity, the shape of which varies according to the manufacturer and desired results. This recess (7) follows a generally elliptical shape (20) rounded, 60 and 30 millimeters along the two main axes.

According to the invention, part of this planar recess (7) receives an annular damping assembly, designated by the general reference (10), located protruding at its center G. This annular assembly (10) follows a general shape also elliptical in dimensions outside 40 and 20 millimeters along the main axes and provides a hollowed-out central part, also elliptical in shape. This shock absorber assembly (10) is formed on top of a plate (11) of aluminum or aluminum-zinc-magnesium alloy, marketed by CEGEDUR PECHINEY under the brand "ZICRAL", having a modulus of elasticity of 70 000
MPa, has a thickness of one millimeter, and weighs a few grams.

 This rigid annular plate (11) of constraints is associated with a visco-elastic sheet (12) with high damping coefficient, the two internal and external faces of which have been previously coated with a thin adhesive layer, so as to favor the connection between the visco-elastic sheet (12) and on the one hand the rigid plate (11) and on the other hand the rear face of the head (3), and more precisely of the recess (7). This visco-elastic sheet (12), for example made of butyl rubber 1.0 mm thick, has a damping coefficient at 25 "C whose delta tangent is between 0.4 and 1.2, preferably between 0.6 and 0.8.

 The characteristic annular damper assembly (10) is arranged on the rear face (7), centered on the center of gravity G of the head, that is to say in alignment with the ideal point of impact, and matches as already said the contours of the edge of the cavity (20).

Ways to realize the invention
In a practical embodiment, as already said, the ratio between the surface of the characteristic annular damping element (10) and the hollow center (15) of this annular element, is between 0.1 and 0.9 and is preferably close to 0.5.

 It has been observed that with a molded iron produced according to FIGS. 3, 4 and 5, the vibrations on impact are reduced by about one third, and that the most harmful vibrations are absorbed more quickly (on average six seconds against sixteen seconds with the same iron not equipped in accordance with the invention).

 In addition, thanks to the annular arrangement of the characteristic damping element (10), the distribution of mass is transported even more towards the periphery of the head without changing the position of the center of gravity of the head. The club thus becomes much more tolerant insofar as it makes it possible to minimize the defects due to the offset of the impact. Finally, the club also becomes more comfortable due to the attenuation of the vibrations transmitted in the user's arm, as well as the significant reduction in the resonance phenomena.

 In the variant embodiment shown diagrammatically in FIG. 7, the inner (30) and outer (32) edges of the annular damping element (10) have different centers (31, 33).

 In the variant shown schematically in FIG. 8, specific to "iron" type clubs, the stress plate (11) is not parallel to the rear face (7) and therefore the layer of visco-elastic material (12 ) has a thickness varying linearly from (12a) the sole (6) to (12b) the upper edge (8).

 In the variant embodiments illustrated in FIGS. 9 and 10, the thickness of the annular damper assembly (10) varies between the interior edge (30) and the exterior edge (32) of the characteristic ring.

Claims (13)

 1 / Head (3) of golf club, including:  a striking front face (5);  a sole (6) extending on the bottom and towards the rear of the face of  strike (5);  a shock absorber assembly (10) arranged at least on another face  that the striking face (5) formed of a stress plate (11)  connected to this face by a layer of viscoelastic material  (12), characterized in that the damping element (10) follows a generally annular shape.  2 / club head according to claim 1, characterized in that the stress plate (11) is a rigid annular plate having a Young's modulus greater than 10,000 MPa, and a thickness of between 0.07 and 2 mm, and in that the layer (12) of viscoelastic material has a thickness of less than one millimeter and has an intrinsic damping coefficient (tangent delta) of between 0.4 and 1.2.  3 / club head according to one of claims 1 and 2, characterized in that the rear face (7) has a cavity disposed above the sole (6), and the bottom of which is parallel to the striking face (5), characterized in that the annular damping element (10) is disposed in this cavity and is centered around the center of gravity G of the head.  4 / club head according to one of claims 1 to 3, characterized in that the ratio between the surface of the annular damping element (10) and the hollow center (15) of this annular element, is between 0, 1 and 0.9.  5 / club head according to one of claims 1 to 4, characterized in that the stress plate (11) is planar and in that the layer of viscoelastic material has a uniform thickness.  6 / club head according to one of claims 1 to 4, characterized in that the stress plate (11) is concave.  7 / club head according to one of claims 1 to 4, characterized in that the stress plate (11) is convex.  8 / "Iron" type golf club, equipped with a head according to one of claims 1 to 7.  9 / club head according to one of claims 1 to 3, characterized in that the inner (30) and outer (32) edges of the annular damping element (10) have different centers (31,33).  10 / golf iron head according to one of claims 1 to 3, having a rear face (7) disposed on the back of the striking face (5) characterized in that the stress plate (11) is not parallel to the rear face (7) and the thickness of the layer of visco-elastic material (12) varies.  11 / dub head according to one of claims 1 to 3, characterized in that the annular damping element (10) has between its inner (30) and outer (32) edges a thickness which varies.  12 / Club head according to one of claims 1 to 3, characterized in that the visco-elastic layer (12) of the annular damping element (10) consists of a stack of several visco-elastic elementary sheets, of different characteristics.  13 / dub head according to one of claims 1 to 3, characterized in that the visco-elastic layer (12) of the annular damping element (10) consists of a juxtaposition in the main plane of visco- elementary areas elastic, of different characteristics.