GB2364511A

GB2364511A - Process for manufacturing a golf club shaft

Info

Publication number: GB2364511A
Application number: GB0109848A
Authority: GB
Inventors: Kuo-Pin Yu
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-06-07
Filing date: 2001-04-23
Publication date: 2002-01-30
Also published as: GB0109848D0; AU4207701A; DE10122347A1; CN1333069A

Abstract

A process for manufacturing a golf club shaft comprising the following steps of; preparing a flexible, impermeable elongated bladder 26 with hollow interior, the cross section tapering off from the first open end to the second closed end; inserting a mandrel into the bladder 26, the mandrel being similar in tapered conical shape to the bladder 26, the mandrel 30 having an axial bore 36 as a recess in the first end, at least one bore passage 37 connecting the axial bore 36 to the periphery of the mandrel 30 and at least one groove 38 extending from the bore passage 37 to the thin end of the mandrel 30; preparing a piece of fibre sheet 40 impregnated with thermosetting resin; dressing the impregnated fibre sheet 40 on the bladder 26 and the mandrel 30; inserting the mandrel 30 along with the bladder 26 and the fibre sheet 40 into a cavity of a mould and injecting fluid through the axial bore 36 and into the groove 38 to fill up and bloat the bladder 26 so as to press the fibre sheet 40 against the inner wall of the cavity of the mould to form a golf club shaft.

Description

2364511 PROCESS FOR MANUFACTURING A GOLF CLUB SHAFT

FIELD OF THE INVENTION

The invention relates to a golf club, in particular a process for manufacturing a golf club shaft by applying a fiber sheet to producing diversified forms with uniformed shaft quality and high yield rate in production.

BACKGROUND OF THE INVENTION

Nowadays, the golf clubs available in the market are in general made of two materials, metal or fiber. The fiber club shafts, for the merit of better flexibility and light weight, have attained the dominion, and is increasingly taking the place of the metal club. The well known practice to make the golf club shaft is to prepare a elongate conical bladder with an opening at one end, which has a large cross section and taper off to a point at the other end. The bladder is implanted with a mandrel and dressed peripherally with an epoxy impregnated fiber sheet. All of three are inserted in a mold, and injected with air to bloat said bladder in a manner such that said fiber sheet will be forced to closely contact the inner wall of cavity of said mold. This is the cavity where the golf club shaft is hereby formed.

This process is in the position to produce a club shaft in diverse shapes with uniform characteristic. However, the air is being injected from the large diameter opening, in most cases, the air injected fails to reach the tip of the tail end of said bladder, in other words, the pressure applied is usually not sufficient enough to expand said fiber sheet at the tail end in said mold cavity. If more air pressure is required, the manufacturer has to face the increase of production cost and the problem of operation safety. It has been long a bottleneck the manufacturers are trying hard to overcome in lifting the yield rate in the production of golf club shaft.

SUMMARY OF THE INVENTION

Viewing from the weaknesses encountered in the production of golf club shaft, the key object of the invention is to provide a novel process for not only manufacturing the golf club shaft with fiber sheet material in uniform quality with diversified shapes, but also effectively lifting the product yield rate and reducing the production cost.

I To attain the aforesaid object, the manufacturing process discovered in the invention mainly comprises the following steps: preparing an flexible, impermeable elongated bladder, with an open at the first end and a seal at the second. A mandrel is inserted into the bladder having a cross section of the first end tapering off at the second 2 end. The mandrel has an axial bore in the recess of the first end and at least a bore passage linking said axial bore to its periphery and at least a groove cut on the surface of the mandrel and extending to the second end. A piece of fiber sheet is dressed on the exterior of said bladder. All of three are placed in a cavity of a mold. A fluid is forced at a predetermined pressure into said axial bore and uniformly filled the interior of said bladder to be bloated which pushes said fiber sheet intimately contacting the inner wall cavity where the shaft is formed with high success and without requiring additional pressure for help the injection of the fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The special features of the invention is explained in greater detail with aid of some embodiments illustrated in the drawings.

Figures I and 2 show the schematic diagram of the golf club shaft manufactured according to the process of the invention.

Figure 3 illustrate the schematic diagram of embodiment of the template and the liquid container. I Figure 4 shows the. stereogram of the template and the bladder.

Figure 5 shows the stereogram of the mandrel.

Figures 6 and 7 display the stereograrn of the mandrel, bladder and 3 fiber sheet.

Figure 8 shows the section of template which is being placed in the mold.

Figure 9 shows the direction 9-9 of figure 8.

Figure 10 shows the schematic diagram of the bladder filled with air.

Figure 11 shows other mold of the invention.

Figures 12 and 13 show the embodiment of shafts in different models manufactured in accordance with the process of the invention.

DETAILED DESCRIPTION OF THE INVENTION

As shown in Figs. I and 2, a golf club (10) contains a head (12), a shaft (14) and a handle (18). When said head (12) of said club (10) strikes a golf ball, a shock wave will climb up from the small end (15) of said shaft (14) to the large end (16) of the handle (18). There are two designs for the shaft, one is that the cross section of the large end (16) tapers off section after section at the small end (15) as shown in Fig.1; the other is that area of the shaft (19) tapers progressively off as shown in Fig.2. In the former design, the shock wave is effectively blockaded to avert the potential injury imposed on the hand and wrist of the golfer. For this reason, this invention decisively adopts the former design for production.

4 Please refer to the Figs 3 through 10, the preferred embodiment of the production steps of making club shaft according to the invention:

First thing to do is to dip a conical template (20) into a container (24) full of liquid material (22) for example such as rubber. As shown in Fig. 3, after a elapse of time, said template is taken off the container, on the surface, said template is stuck with a film -of rubber at a predetermined thickness. As shown in Fig.4, peel the rubber film off the template (20) after dried up, this rubber film forms a flexible fine long conical bladder (26) the invention wants, it has an hollow interior with the first end (261) open and the second end (262) closed. The cross section of said first end (261) begins to contract in diameter to said second end (262). The liquid material can be of plastic solution, not rubber liquid alone, as long as it can form a film over the template after dried- The bladder (26) is impermeable.

The next step is to insert a mandrel (30) into said bladder (26) as shown in Fig. 6. In Fig. 5, said mandrel (30) has a shank (32) similar to the bladder (26), the cross section of the mandrel diminishes in diameter from the first end (321) to the second end (322). The head (34) of the mandrel (30), larger than the neck (33) in cross section, is the free end. An axial bore (36) extends inward as a, tecess, pas4ing said neck (33) and said first end (321). Three-way bore passage (37) will come out of said shank (32). Three grooves (38) is cut on the surface of the shank (32), beginning with said bore passage (37) and ending at said second end (322), of which, said bore passages (37) are spaced at 120', so do three grooves(38).

Followed is to prepare a fiber sheet (40). It can be woven with carbon fiber, glass fiber or other suitable fiber. The fiber sheet is submerged in the thermosetting resin such as epoxy resin to be fully impregnated in the fabric pores. The impregnated fiber sheet (40) is dressed along the bladder (26), then both in turn wrap the shank (32) of the mandrel (30) as shown in Figs. 6 and 7.

As shown in Figs. 8 and 9, said mandrel (30) along with said bladder (26) and said fiber sheet (40) is grafted into a mold (42). The mold (42) has a deep cavity (44) in the ladder structure with dimension reduced progressively from the first ladder end (44 1) to the second ladder end (442). Said cavity has an open (444) having a large diameter than said neck (33) of said mandrel (30) for easily housing said neck (33) of said mandrel (30) and said bladder (26). Said cavity further has a depression (446) at the end of the second ladder end (442) which permits said second end (322) of mandrel (30) and said bladder end (26) to settle in. Said shank (32) of said mandrel (30) is positioned in the center of said cavity (44) and there reserves a predetermined free space between the cavity wall (44) and said fiber sheet (40).

Now heat said mold (42), and in meantime, inject fluid such as air with a predetermined pressure into said axial bore (36) of said mandrel (30). Said injected fluid will flow through said bore passages (37) and said grooves (38) to disperse allover and to bloat said bladder (26) as well, under this circumstance, said fiber sheet is being propelled to intimately contact the inner wall of said cavity (44). As shown in Fig. 10, the epoxy resin is heated and hardened to form a golf club shaft within said cavity (44).

6 It is noted that said grooves (38) are designed to link with said bore passages (37) and said second end (322) on said shank (32) of said mandrel (3 0), permitting the fluid flow freely from said first end (26 1) to said second end (262) of said bladder (26) to eliminate the weak point which happens more than often in the conventional production where the injected fluid can never reach to the bladder tail, the fiber sheet is not being expanded completely, as result the product yield rate is very low. The key object of the invention is to improve such a weakness.

In the embodiment of the invention, the shaft is the ladder diminishing type for taking as an example purpose. The manufacturing principles described in the invention can be applied to production of the shaft in any shape or form, even complicated ones without hurting the supremacy of the mechanical function. As shown in Fig. 2, the cross section of the shaft (19) is diminishing regularly. The process for manufacturing said shaft (19) is the same with preceding embodiment of the invention, only the shape of the cavity (72) of the mold (70) is modified to taper off from the first end (74) to the second end (76), as shown in Fig. 11. Example of irregular shape of shaft is shown in Fig. 12. The shaft (50) has a diminished cross section at point (52), and in Fig. 13, the shaft (60) the diminished cross section takes place on points 62 and 64.

7

Claims

WHAT IS CLAIMED IS:

1. Process for manufacturing a golf club shaft comprising the following steps of (a) preparing a flexible, impermeable elongated bladder with hollow interior, having a first end open and a second end closed, the cross section tapers off from said first end to said second end; (b) inserting a mandrel into said bladder, said mandrel is similar in conical shape to said bladder and the cross section tapers off from the first end to the second end, said mandrel has an axial bore as a recess in said first end,, at least one bore passage connected said axial bore to periphery, and at least one groove lining from said bore passage to said second end; (c) preparing a piece of fiber sheet impregnated with thermosetting resin;

(d) dressing said impregnated fiber sheet on said bladder and said mandrel; (e) inserting said mandrel along with said bladder and said fiber sheet into a cavity of a mold; (f) injecting with a predetermined pressure a fluid through said axial bore and said groove to fill up and bloat said bladder so as to press said fiber sheet closed against the inner wall of said cavity of said mold, there a designed shaft is formed.

2. The manufacturing process as defined in claim 1, wherein a conical template is used to be dipped with a film of liquid material in a predetermined thickness, after drying up, said film constitutes said bladder.

3. The manufacturing process as defined in claim 2, wherein a film of liquid material formed and dried on said template is the plastic solution.

4. The manufacturing process as defined in claim 2, wherein said liquid material is liquid rubber.

5. The manufacturing process according to any one of the preceding claim, wherein preferably there are three bore passages.

6. The manufacturing process as defined in claim 5, wherein said bore passages are spaced at 1200 one another.

7. The manufacturing process according to any one of the preceding claims, wherein preferably there are three grooves.

8. The manufacturing process as defined in claim 7, wherein said grooves are spaced at 1200 one another.

9. The manufacturing process according to any one of the preceding claims, wherein said fluid is air.

IO.The manufacturing process according to any one of the preceding claims, wherein at least part of the interior of said cavity appears in ladder 9 type, and its cross section diminishes progressively from one end to the other end.

I I.The manufacturing process as claimed in any one of claims I to 9, wherein at least part of internal cross section of said cavity tapers off progressively firom one end to the other end.

12.A manufacturing process substantially as hereinbefore described with reference to Figures I and 3 to 10, Figures 2 to 7 and 11, Figures 3 to 7 and 12, and/or Figures 3 to 7 and 13 of the accompanying drawings.