GB2124911A

GB2124911A - A wood-type golf club

Info

Publication number: GB2124911A
Application number: GB08320458A
Authority: GB
Inventors: Akiteru Fujimura
Original assignee: Sumitomo Rubber Industries Ltd
Current assignee: Sumitomo Rubber Industries Ltd
Priority date: 1982-07-31
Filing date: 1983-07-29
Publication date: 1984-02-29
Also published as: GB2124911B; JPS5925766A; GB8320458D0; JPS631866B2

Abstract

A wood-type golf club comprises a reinforcing fade plate or insert (11) embedded in a recess (12) formed in an impact front face (13) of a wooden club head block (14), which insert (11) is made of vulcanized fibre and formed in such a configuration as to include a substantially horizontally extending upper edge (19) and a pair of side edges (20, 21). The fibres contained in said insert (11) are orientated laterally in substantially the same direction as the upper edge (19). <IMAGE>

Description

SPECIFICATION Awood-type golf club This invention relates to an improvement in a golf culb, and more particularly to a face plate arrangement in a club head of a "wood-type" golf club.

It is generally known that a wood-type golf club has a reinforcing face plate (hereinafter called "insert") embedded in and permanently attached by adhesive or other to an appropriate recess formed in the center of an impact front face of the wooden club head block, in such a manner that an external face of the inert lies substantially flush with the impact front face of the club head block.

The insert may generally be made of ABS resin, vulcanized fibre, light alloy or other suitable material. Among these materials for the inserts, vulcanized fibre is now widely used because of its good mechanical strength and dimensional stability in addition to inexpensiveness. The present invention is specifically directed to the particular arrangement of the insert that is made of vulcanized fibre sheet.

The background of the invention will now be described hereinbelow with reference to Figures 1 to 3 of the accompanying drawings, which illustrate the conventional face plate arrangement in a wood-type golf club head H and the conventional method for producing the face plate or insert I from known vulcanized fibre sheet S.

As particularly shown in Figure 3, the vulcanized fibre made insert I may generally be formed in such a conventional configuration, e.g., substantailly trapezoidal or other, as including a relatively narrow upper edge 1 and a pair of diverging side edges 2,3 joined at their lower ends by a bottom edge 4. On the other hand, a recess R formed in the wooden club head block H, in which the insert I is embedded, has such a configuration as substantially corresponding to that of the insert and including a pair of side edges 5, 6, each of which interfaces the aforesaid side edges 2, 3, respectively, as illustrated in Figure 1.

In the conventional wood-type golf club head with a vulcanized fibre made insert embedded therein, it is observed that undesirable interface separation is likely to occur between the aforesaid edges 2,3 of the insert land the opposing edges 5, 6 of the recess R, thereby to produce narrow but visible gaps G of about 0.1 to 0.3mm thickness therebetween, as shown in Figure 1.

As a matter of course, such visible separation gaps G mar the glub head appearance, with the result that the commercial value of the club is more or less reduced.

In order to clear up the cause or reason why the narrow gaps G in question are developed between the interfacing side edges 2, 3, and 5, 6, the Inventor conducted the repeated experiments with respect to the method of producing the golf club head, in particular, with respect to dimensional changes in the insert and the wooden club head block, due to variations in degrees of moisture content; and carefully analyzed the obtained results.

The typical experiments were carried out with the following particulars Vulcanized fibre sheet S as material, in which the fibres contained therein were orientated longitudinally of the sheet as indicated by an arrow L (Figure 2), was unrolled from a roll Tin the axial direction Y, i.e., in the direction of an arrow A, as shown in Figure 2.

In the course of unrolling, the material sheet S was predried so as to have 7 to 9% of moisture content.

A number of inserts I of substantially trapezoidal configuration were produced by known punchingout technique from the sheet S, in such a conventional manner that the upper and the bottom edges 1, 4 of each of the inerts I extended crosswise of the longitudinal axis of the sheet S, so that the longitudinal axis y of each of the produced inserts I was brought in line with the longitudinal axis y' of the sheet S, as shown in Figures 2 and 3. Accordingly, the three-dimensional axes x, y, z, of each of the produced inserts I corresponded to the axes x', y', z' of the material sheet S. As a result, the fibres contained in each of the inerts thus produced were oriented longitudinally of the insert so that the axis of each of the fibres was directed in the direction of the arrow L (Figures 1 to 3).

Each of the produced inserts I had 7 to 9 % of moisture content, while each of the wooden club head blocks (persimmon) H was predried to present about 8 % of moisture content.

Then, the predried inserts I together with the predried wooden club head blocks H were dried at 70 0coin a hot air drier for 40 hours, 60 hours, 80 hours and 150 hours, respectively. Weight change rate as well as dimensional change rate in the inserts I and also those in the wooden blocks H were measured after drying for 40 hours, 60 hours, 80 hours and 150 hours, respectively.

The obtained results are shown in Polygons (I), (II), (III), (IV) of Figure 4, wherein the solid polygonal lines indicate the weight or the dimensional changes in the inserts I while the dotted lines w indicate the weight or dimensional changes in the wooden club head blocks H.

More particularly, Polygon (I) of Figure 4 comparatively indicates the increasing loss in weight of the inserts I and that of the wooden blocks H, on drying for 40 hours, 60, hours, 80 hours, and 150 hours, respectively.

Polygon (Il) comparatively indicates the increasing contraction rate in x-axis direction of the inserts I and that of the wooden blocks H on the same drying.

Polygon (III) comparatively indicates the increasing contraction rate in y-axis direction of the inserts I and that of the wooden blocks H on the same drying.

Polygon (IV) comparatively indicates the increasing contraction rates in z-axis direction of the inserts I and that of the wooden blocks H on the same drying.

From the obtained data as described and shown in the graphs (I) to (IV) in Figure 4, it has been proved that the vulcanized fibre made insert has such a particular anisotropic character that its contraction rate in the direction of y-axis is relatively smaller than that in the direction of x-axis. This means that the vulcanized fibre made insert is less contracted in the direction of its fibre orientation (i.e. direction L of fibre axis as indicated by the arrow L) than in the direction transverse to the fibre axis (i.e., direction as indicated by an arrow M in Figure 3).

Further, it has also been proved that the x-axis directional contraction rate of the vulcanized fibre made inserts I is generally greater in measured value than that of the wooden club head blocks H.

However, the measured values relating to the difference in the contraction rates between the inserts I and the wooden blocks H may vary in dependence upon different natural characteristics of different wooden materials. Even when the club head blocks are made of the same kind of wood, for example persimmon, the contraction rate thereof may more or less vary in dependence upon the particular property inherent to a particular individual club head block. Such non-uniformity in material should often be accepted when natural material such as wood is employed.

As will be easily comprehensible from the above analysis of the obtained data, it has been cleared up that the undesirable development of the above discussed gaps G between the interfacing edges 2, 3 and 5, 6 are primarily caused by the considerable difference in the x-axis directional contraction rates between the vulcanized fibre made insert and the wooden club head block.

It is, therefore, an object of the present invention to substantially reduce the above-discussed problem with respect to the club head appearance which causes decrease in the commercial value of the club.

Another object of the invention is to provide an improved wood-type golf club wherein arrangement is made to substantially reduce undesirable development of separation between the side edges of a vulcanized fibre made insert and those of a recess formed in an impact front face of a wooden club head block for embedding the insert therein.

According to the present invention, there is provided a wood-type golf club including a wooden club head block with a vulcanized fibre made insert embedded in a recess formed in an impact front face of the club head block, wherein fibres contained in the insert are orientated crosswise of the longitudinal (vertical) axis of the insert so that each axis of the contained fibres is directed substantially laterally.

The invention is based on analysis of the data obtained from the experiments described in detail in the foregoing.

The invention will now be further described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a perspective view illustrating a conventional wood-type club head having a vulcanized fibre made insert embedded in a recess formed in its front club face; Figure 2 is a reduced schematic perspective view showing a conventional method for producing the vulcanized fibre made inserts; Figure 3 is a perspective view illustrating a typical example of vulcanized fibre made insert produced by the method as shown in Figure 2; Figure 4are four graphs comparatively indicating weight and dimensional changes on drying of the vulcanized fibre made inserts and the wooden club head blocks; FigureS is a similar view to Figure 1, but illustrating a wood-type club head according to the present invention;; Figure 6 is a similar view to Figure 2, but showing a method for producing the vulcanized fibre made inserts according to the present invention; Figure 7 is a similar view to Figure 3 showing a typical example of the vulcanized fibre made inserts according to the present invention ; and Figure 8 is a graph comaparatively indicating the increasing contraction rate of vulcanized fibre made inserts in the direction of x-axis and that of wooden club head blocks according the present invention.

Referring now back to the accompanying drawings, in particular, to Figures 5 to 8, a wood-type golf club head 10 is illustrated as having a reinforcing face plate or insert 11 conventionally embedded in and permanently attached to an appropriate recess 12 formed substantially in the center of a front impact face 13 of a club head block 14 made of persimmon or other suitable hard wood. The external face of the insert 11 lies substantially flush with the front face 13 of the club head block 14, conventionally.

The recess 12 may be formed in such a conventional configuration, e.g., substantially trapezoidal or other, as including a relatively narrow opening upper edge 15 and a pair of diverging side edges 16, 17 joined at their lower ends by a bottom edge 18.

While, the vulcanized fibre made insert 11 should be formed in such a configuration as substantially identical to that of the recess 12, so that the insert 11 can be tightly fit into the recess 12, with its three edges 20, 21, 22, being in tight contact with the interfacing edges 16, 17, 18, respectively, as illustrated in Figure 5.

The inserts I may, for instance, be produced by known punching-out technique from vulcanized fibre sheet material S which is unrolled from a roll T in the direction of its longitudinal axis y', i.e., in the direction of the arrow A, as illustrated in Figure 6.

The fibres contained in the sheet S are orientated in the same direction as the longitudinal axis y' of the sheet S, so that the axis of each of those fibres is directed in the direction of the arrow Las shown in Figure 6.

Each of the inserts 11 of substantially trapezoidal configuration is punched out of the sheet S in such a manner that the upper and the bottom edges 19, 22 of each insert I extend substantially in parallel with the longitudinal axis y' of the sheet S, that is, in the axial direction L in which the fibres contained in the material sheet S are oriented, as particularly illustrated in Figure 6. Accordingly, the axes x, y of each insert I are angularly turned by 90 with respect to the axes x', y' of the sheet S, as will be apparent from Figures 5 and 6. Thus, in each of the produced inserts 11, the contained fibres are directed in the x-axis direction, as shown in Figure 5.

As having been proved by the described experiments and shown in Polygons (II) and (III) of Figure 4, the contraction rate of the insert in the axial direction L of the contained fibres is relatively smaller than that in the cross direction M transverse to said axial direction L. Therefore, the vulcanized fibre made inserts 11 according to the present invention are less contracted in its x-axis direction, as compared to the conventional vulcanized fibre made inserts I having the contained fibres directed in y-axis direction as shown in Figure 1.

Further, as a resu It of the experiments with respect to the vulcanized fibre made insert 11 according to the present invention, it has been proved that the contraction rate in its x-axis direction is always smaller than that of the club head block 14 made of wood (persimmon). The result of the experiments is shown in Figure 8.

Thus, when the vulcanized fibre made insert 11 according to the present invention is embedded in the recess 12 formed in the impact front face 13 of the wooden club head block 14, it is possible to substantially reduce the undesirable development of separation or gaps between one side edge 20 of the insert 11 and the interfacing side edges 16 of the recess, and/or between the other side edge 21 of the insert 11 and the interfacing side edge 17 of the recess.

On the other hand, it is considered that the contraction rate of the insert 11 in its y-axis direction is greater than that of the contentional insert I.

However, this will not invite any substantial disadvantages in the club head appearance and function of the golf club.

The vulcanized fibre made inserts according to the present invention can be produced without any substantial change or modification in the conventional manufacturing equipments as already installed in the golf club industries.

Claims

1. Awood-type golf club comprising a reinforcing face plate or insert (11) embedded in and permanently attached to a recess (12) formed in an impact front face (13) of a wooden club head block (14), in which said insert (11) is made of vulcanized fibre and formed in such a configuration as including a substantially horizontally extending upper edge (19) and a pair of substantially vertically extending side edges (20, 21), characterized in that fibres contained in said insert (11) are oriented laterally in such a direction substantially same as a direction in which said upper edge (19) extends.

2. A wood-type golf club substantially as hereinbefore particularly described with reference to, and as illustrated in Figures 5 to 7 of the accompanying drawings.