Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – With internal application of fluid pressure
Patent
1991-10-25
1994-01-11
Woo, Jay H.
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
With internal application of fluid pressure
273 80R, 273167H, 2642711, 26432818, B29C 4500, A63B 5310
Patent
active
052778665
DESCRIPTION:
BRIEF SUMMARY
This is a national stage application of PCT application number PCT/GB 90/00631.
FIELD OF THE INVENTION
This invention concerns improvements in or relating to golf clubs and particularly but not exclusively to a method of manufacturing a golf club with an integral head and shaft.
SUMMARY OF THE INVENTION
According to the present invention there is provided a method of manufacturing a golf club by injection molding, the method comprising introducing a required volume of polymer into a correspondingly shaped mold, introducing a required volume of pressurised fluid such that the fluid urges the polymer to line the walls of the mold, and maintaining the fluid under pressure for a predetermined period of time to allow the hollow club thus formed to cool, the polymer being fed into the mold such that the wall thickness of the shaft of the club increases towards the head of the club.
The fluid is preferably introduced into the mold simultaneously with the polymer after a first portion of the polymer has already been introduced thereinto.
The fluid and polymer may be introduced into the mold at substantially the same location. Alternatively the fluid may be introduced into the mold downstream of introduction of the polymer.
Preferably the polymer includes reinforcing fibers which may be of the long grade type. The polymer may be nylon or acetal, and the fibers may be glass, aramid, or carbon.
A sole plate and/or other items may be positioned in the mold prior to molding, to be incorporated into the club head.
The mold may be shaped such that openings are formed extending in to the club head which can subsequently be filled with a relatively dense material to weight the club.
A filler may be provided in the polymer such as talcum powder.
After molding the club may be filled with a curable material which may be resinous.
Also according to the present invention there is provided a golf club manufactured by a method according to any of the preceding eight paragraphs.
Examples of how the invention may be carried out will now be described by way of example only with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic plan view of a mold usable with the invention;
FIG. 2 is a cross-sectional side view of the mold of FIG. 1; and
FIG. 3 is a diagrammatic plan view of apparatus usable with the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A golf club may be formed by feeding a predetermined weight of aramid reinforced nylon thermoplastics material from the screw of an injection molding system into the handle end of a suitably shaped mold. After an initial portion of the thermoplastic has passed into the mold a stream of a predetermined volume of nitrogen under pressure is introduced into the center of the thermoplastic feed to urge the thermoplastic against the inner walls of the mold to form a hollow club. When the feed and stream into the mold have been completed, the mold is maintained under pressure for a period of time, e.g. twenty seconds, to allow the thermoplastic to set. The nitrogen is then released and the mold opened to release the club.
The aramid fibers are of the long grade type and will be typically 10 mm long as opposed to 0.2-0.4 mm for short grade type fibers. This length of fibers gives a relatively stiff shaft.
If required a sole plate can be positioned in the mold prior to molding which will adhere to the thermoplastic to provide weight in the required position on the base of the club's head and also protection against abrasion from rubbing on the ground. The sole plate can be made from any suitable material such as brass. The sole plate can be aligned in the mold such that the club being formed adopts the correct lie for a particular player. For example a taller player holds any one club at a greater angle to the vertical than a shorter player holds the same club, but preferably the base of the club should still be parallel to the ground for both players.
The polymer is fed into the mold such that the shaft thickness increases towards the
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Adams, III W. Thad
Davis Robert B.
Oakbray Investment Company, Ltd.
Woo Jay H.
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