Weight-balanced Golfing Iron

Abstract

The heads of a set of golfing irons are provided with weight balancing plugs and metal powder, during their production, to provide an accurately matched set. Two plugs are located in bore means in the head; one plug is elongated and less dense than the head metal; another plug is short and located at the heel end of the bore means; and the metal powder particles are confined between the plugs and have greater density than the head metal.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to golfing irons, and more particularly concerns the construction and rapid production of such golf clubs in a manner to facilitate balancing of different irons in a set, thereby to form a matched set.

There is a need for a rapid and inexpensive method to produce accurately matched sets of golfing irons, and particularly irons the heads of which are further characterized by lightweight construction. No way has been known, to my knowledge, to produce irons having the unusually advantageous features of construction as are characterized by the present invention, and as facilitated by the method of fabrication to be described.

SUMMARY OF THE INVENTION

It is a major object of the invention to meet the above need through provision of golfing iron capable of rapid and accurate balancing, and a method for accomplishing same. Basically, in accordance with the invention, the head of the iron is provided with an elongated opening extending within a base portion between the toe and heel; an elongated balancing plug extending within that opening; a relatively short plug also extends within the opening and is spaced from the elongated plug, and a selected amount of weighting material is received or placed in that space during the final balancing step. Such material may, for example, consist of a heavy metal powder such as tungsten, and the elongated balancing plug may consist of a metal substantially less dence than the head metal, as for example aluminum. Further, the retainer plug may retain the elongated plug in a counterbore and against a counterbore shoulder, and the short plug may be received in a bore near the heel of the head, so that the weighting material or powder is also located near the heel, as will be seen.

The method of producing the balanced iron typically involves the steps of forming a wax replica of the head and embedding a ceramic core in the base portion of the replica, that core having the configuration of the described bore and counterbore; forming a ceramic mold about the replica and curing same at elevated temperature to also melt out the wax; pouring molten head metal into the mold cavity and removing the mold after cooling of the metal head; removing the core from the head, as by acid etching; introducing an elongated lightweight metal balancing plug and a heavy metal powder into different interior portions of the opening and plugging the opening at its opposite ends. Different length balancing plugs may be used for different irons of a set to match or equalize their weights, and "fine" or accurate balance may be achieved by controlled introduction of the heavy metal powder, during the balancing procedure.

These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following description and drawings, in which:

DRAWING DESCRIPTION

FIG. 1 is a rear side elevation of the head of a golfing iron embodying the invention;

FIG. 2 is a toe end elevation of the FIG. 1 head;

FIG. 3 is a front side elevation of the FIG. 1 head, the lower portion of which is cut away to show interior structure;

FIG. 4 is a section taken on lines 4--4 of FIG. 1;

FIG. 5 is a section taken on lines 5--5 of FIG. 1;

FIG. 6 is a view like FIG. 3 but showing the head at a stage during its manufacture;

FIG. 7 is a toe end elevation of the FIG. 6 head;

FIG. 8 is a block diagram showing a sequence of steps in the club head fabrication process; and

FIG. 9 is an elevation showing balancing of the club.

DETAILED DESCRIPTION

Referring first to FIGS. 1-5 the metallic head 10 of an upright golf club iron 9 includes a hosel 11, toe 12 and heel 13, a front face 14 to strike a golf ball, a rear side 15 recessed at 16, and a base portion 17 the bottom 17a of which is flat in the lateral direction viewed in FIG. 4, and longitudinally convex, downwardly. Front face 14 has an inclination .alpha. from a vertical plane which may vary as required for the intended use of the iron; thus, the illustrated iron is intended to represent any of the irons that a golfer might use, and including Nos. 1 to 9, wedge, putter, etc.

In accordance with an important aspect of the invention, an elongated through opening extends generally longitudinally within the base portion 17 between the heel and toe, that opening defined by a relatively short bore 18 proximate the heel and a relatively long counterbore 19. The latter may typically extend between the bore 18 and the toe 12, as best seen in FIG. 3. An elongated plug 20 extends within the counterbore 19 to provide balancing, different length plugs being used for different irons in a set, to provide "coarse" equalization of weight. Plug 20 is held in place abutting the counterbore shoulder 21 by a short retainer plug 22 having threaded connection with a tapped section 19a of the counterbore, and a suitable hardenable fill material 23 fills the counterbore space between plug 22 and the curvature at which the toe 12 merges with the base lower face 17a. Material 23 may consist of metal powder in a hardenable carrier resin such as an epoxide, or an equivalent substance. Plug 20 may be of a material (as for example aluminum) substantially less dense than the steel metal of the club head.

A relatively short plug 24 is threaded into a tapped section 18a of the bore 18, and sealed in position by hardenable fill material 25 (of a composition similar to that of material 23, for example). The space 26 formed in the bore 18 between plugs 20 and 24 is of a predetermined size, and is adapted to receive an amount of heavy metal powder 27 (as for example tungsten) for "fine" weight balancing purposes, as will appear. A precise amount of such powder, as determined by balancing the club after completion of fabrication, is inserted into space 26 prior to insertion of the plug 24 and fill material 23. Space 26 is of a length substantially less than the length of plug 20, and has a volume such that it is normally only partly filled with sufficient weighting material 27 needed for balancing. Accordingly, the coarse and fine balancing means 20 and 27 also serve to lighten the weight of the club head as well as to enable accurate and rapid balancing as required to "match" a set of irons. Note that the recess 16, which contributes to the light weight characteristics of the head, is directly above the base portion 17 that contains the plug 20. The inner wall 16a of the recess and the front face 14 define therebetween a relatively thin plate 28 which receives the direct impact developed when the head strikes the golf ball.

Hosel 11 includes an elongated stem 11a which contains an elongated bore 29, the latter also contributing to reduction of head weight. The stem is attached to the club shaft 30 as by a telescopic interfit of the shaft end over the stem, at 30a in FIG. 1.

The head 10 may be fabricated, with unusual advantage, in accordance with steps outlined in FIGS. 6-8, described as follows: initially, a wax impression 35 of the head is made as seen in FIG. 6, the bore and counterbore 36 and 37 (corresponding to bore 18 and counterbore 19) are formed in the wax, and a ceramic insert or core 38 is implaced to extend in the bore and counterbore 36 and 37. One suitable ceramic consists of fused silica (94 percent by weight) and alumina (6 percent by weight), a product of American Lava, and of Fibeco. Inc. These steps are indicated at 39 in FIG. 8. Next, a ceramic mold is formed about the wax impression, as indicated at 40 in FIG. 8. This may be done by dipping the wax impression into a thick, liquid ceramic mix (as for example waterglass) applying "stuccoing" particles to the ceramic coat, (as for example powdered fused silica, or walnut shell particles) and repeating these steps to build up a reinforced liquid ceramic coat of about one fourth inch thickness on the wax impression.

The coating is then baked at between 1,500.degree. and 2,000.degree.F to melt the wax and cure the ceramic coating, leaving a cavity of the outline form of the wax impression in FIG. 6, but with the plug 38 still in place. This step is indicated at 41 in FIG. 8. Next, as indicated by step 42, molten steel is poured into the mold cavity, as via the entrance formed by wax protrusion 43, the steel enveloping the plug 38. After cooling, the mold is broken off and the plug is removed as by an etch, a suitable etchant being sodium hydroxide applied at about 1,100.degree.F for about 1 hour. This final step is indicated at 44 in FIG. 8.

After removal of the steel protrusions corresponding to the wax protrusions 43 and 45, the bores 18 and 19 are tapped and the plugs fitted in position as previously described.

FIG. 9 illustrates balancing of the club as by supporting it at the handle, as by the bracket 46 and on a fulchrum 47, and at the head end at 48. Metal powder is poured at 49 into the space 26 until a plunger on a pre-set scales 50 is deflected downwardly, indicating that balance in relation to other irons has been achieved.

Claims

I claim:

1. In a golf iron,

a. a metallic club head having a toe and heel, a front face to strike a golf ball, a rear side, the head having an elongated base portion extending between the toe and heel,

b. there being an elongated through opening extending within the base portion between the heel and toe,

c. an elongated balancing plug extending within the opening, and

d. a relatively short plug extending within the opening and spaced from the elongated plug for reception therebetween of a selected amount of weighting material in the form of metal particles having a density substantially greater than the density of the head metal, said elongated plug consisting of a metal substantially less dense than the head metal,

e. said opening defined by bore means one portion of which receives the short plug at the heel end of the head, and the elongated plug retained in another portion of the bore means.

2. In a golf iron,

a. a metallic club head having a toe and heel, a front face to strike a golf ball, a rear side, the head having an elongated base portion extending between the toe and heel,

b. there being an elongated through opening extending within the base portion between the heel and the toe,

c. an elongated balancing plug extending within the opening, and

d. a relatively short plug extending within the opening and spaced from the elongated plug for reception therebetween of a selected amount of weighting material in the form of metal powder having a density substantially greater than the density of the head metal, said elongated plug consisting of a metal substantially less dense than the density of the head metal,

e. said opening being defined by a bore receiving the short plug at the heel end of the head, and a counterbore receiving the elongated plug.

3. The golf iron of claim 2 including a retainer plug in the counterbore retaining the elongated plug in end-to-end relation with a counterbore shoulder formed between the bore and counterbore.

4. The golf iron of claim 2 wherein the base portion has a lower face which merges with the toe along a convexly curved surface intercepted by said counterbore.

5. The golf iron of claim 1 wherein the head rear face is inwardly recessed directly above said base portion containing said through opening.

6. The golf iron of claim 5 wherein the hosel includes an elongated stem to be attached to a club shaft, the stem containing a bore.

7. The golf iron of claim 2 including hardenable material filling the bore and counterbore at the ends thereof adjacent the toe and heel of the head.