WO1996019266A1

WO1996019266A1 - Sportings grips

Info

Publication number: WO1996019266A1
Application number: PCT/AU1995/000861
Authority: WO
Inventors: Richard Lance Clarke
Original assignee: Richard Lance Clarke
Priority date: 1994-12-21
Filing date: 1995-12-19
Publication date: 1996-06-27
Also published as: AUPN018894A0

Abstract

A grip for handles of sporting articles such as golf clubs, hocket sticks, cricket bats, tennis racquets and the like comprises a generally tubular body (67) of elastomeric material, the tubular body including a parallel sided shaft receiving recess and a contoured outer surface simulating a helically wound tape, the simulated helical tape winding extending in a clockwise direction from a closed end (68) to an open end (69) with a pitch of from 17 mm to 22 mm and a pitch angle between 10° and 20°.

Description

TITLE SPORTING GRIPS

FIELD OF INVENTION This invention relates to hand grips for articles and particularly, although not exclusively, with hand grips for sporting articles such as tennis racquets, squash racquets, cricket bats, hockey sticks, lacrosse sticks, golf clubs and similar articles which require a handle or shaft. BACKGROUND OF THE INVENTION In view of the great variety of handle and shaft lengths as well as cross-sectional shapes and sizes, it is common practice to spirally wrap the handle or shaft of a sporting article with a moisture absorbent leather or fabric tape to obtain a non-slip grip. However, a particular disadvantage of such hand grips is the need for frequent replacement due to excessive wear or soiling through constant use. Another disadvantage of such hand grips is that unless the spirally wound grip is attached to the shaft or handle by bonding agent or adhesive the grips can loosen and/or stretch and therefore move on the handle or shaft thereby providing an uneven or uncomfortable hand grip. Traditionally, leather or fabric tape grips were wound helically in a counterclockwise direction about the shaft or handle of sporting articles from the butt end towards the end of the grip region intermediate the length of the sporting article.

In order to overcome the problems with spirally wound leather or fabric tapes, elastomeric coating compositions or moulded elastomeric grips have been proposed. These grips often include surface textures, projections or contours in an endeavour to improve grip comfort and to reduce slippage.

U.S. patent No. 3972528 describes a grip for a base ball bat having of a neoprene rubber coating with a "tackifier" comprised of zinc oxide, flocked silica and rosin. The coating has an open pore structure and the silica particles provide a sandpaper-like feel. It is claimed that this coated grip increases in tackiness as a user's hands get hotter and sweatier

Australian Patent Application No 42836/89 describes a moulded elastomeric grip for golf clubs This grip comprises an elongate generally frusto conical body having a parallel sided cylindrical shaft receiving recess therein The grip surface has moulded therein a pattern of shallow, narrow grooves comprising spaced curved axial grooves extending over a lower sur ace of the grip and spaced radial grooves extending over the upper surface of the grip U S Patent No 3606326 describes a golf club grip formed from an elastomeric sponge having a shore A hardness in the range 5-40, the sponge grip body being covered with a solid layer of elastomeric material The end cup of the grip includes an aperture to facilitate fitting of the grip to a shaft under fluid pressure internally applied via the aperture International Patent Application No PCT/US91/04237 describes an improved method for the manufacture of moulded rubber golf club grips The grips posses a conventional external shape in that they are generally frusto conical and taper from a closed butt end of larger diameter to an open end of smaller diameter In contrast to earlier moulded grips of this type the shaft receiving aperture formed in the grip is tapered from a larger diameter adjacent the open end of the grip towards a smaller diameter adjacent the butt end of the grip This reverse taper feature facilitates removal of the mould core pin without damaging

This reference also describes a rubber material for the grips which retains "tackiness" for a longer period than conventional rubber grips but there is no disclosure of the means for achieving this

Australian Patent Application 14426/83 describes a moulded elastomeric grip for a variety of sporting articles and hand tools The grip is compression moulded in a die assembly having a smooth surfaced female mould and a contoured mould core pin to form a grip having a smooth outer surface and a ridged, grooved, protuberant or indented inner surface

When applied to the shaft of a sporting article such as a golf club, the engagement between the sharp protuberant portions or ridges on the inner surface of the grip produces smooth undulating distortions in the outer surface of the grip corresponding to the inner contours

This invention is exemplified by frusto conically shaped golf club grips tapering from a closed enlarged end to a narrow open end, the wall thickness of the grip also reducing progressively towards the narrow end of the grip The grip, when applied to a golf club shaft produces a smoothly insulating contour simulating a spiral tape wrap extending in a clockwise fashion starting from the butt end

While the primary purpose of this grip configuration is stated to achieve ease and economics in the manufacture of female mould/male core pin assemblies, there are substantial disadvantages associated with this moulding process and the grips so produced

As highlighted in prior art reference PCT/US91/04237 referred to above, the removal of even a smooth parallel sided cylindrical core pin can distort and damage a soft elastomeric moulding It is considered that in the case of the contoured core pin of Australian Patent No 14426/83, it would be virtually impossible to remove the core pin without serious damage or distortion to a freshly moulded soft elastomeric grip Certainly, an internal lubricant/mould release agent such as a stearate would be required to assist in this regard but this would also give rise to a stearate coating on the outer surface of the grip thus negating any non slip properties imparted by contouring

Although the drawings illustrate a simulated clockwise helical wrap starting from the butt end, it is stated that "the distortions imposed on the grip when it is forced upon the handle can be arranged to correspond, at least in general terms, to those experienced by a natural material strip when it is wound, further increasing the behavioural similarity achieved" It is clear from the statement that the significance of the direction of helical wrap whether clockwise or anticlockwise was not apparent to that inventor as investigations have shown that the traditional direction of spiral wrap for sporting articles is always counterclockwise starting from the butt end

Moreover, the pitch angle of the helix of this reference is shown as 30° and for a "standard" 25cm (10 inches) golf club grip, the spacing between adjacent zenith or nadirs in the resultant contoured outer surface is about 2 5cm (1 inch) This combination of pitch angle and spacing does not correspond to the average spacing and angularity of a user's fingers when gripping a sporting article Thus, apart from being uncomfortable in use, such grips give rise to uneven finger gripping pressure about the grip which exacerbates the tendency of slipping or rotation in a user's hand or hands

A further disadvantage of grips of this kind is that when secured to a parallel sided shaft of a sporting article, only a very small proportion of the inner surface of the grip actually contacts the shaft As such, it is very difficult to achieve a secure grip between the grip and shaft either by fπctioπal engagement or adhesive without slippage of the grip relative to the shaft

Yet another disadvantage of the grips of this type arises from the combination of regularly spaced internal contours and the progressive change in wall thickness between the butt end and the open end of the grip When applied to a parallel sided shaft, this gives rise to substantial variation in the flexibility of the grip between a relatively firm butt end and an unduly soft and spongy feel towards the narrow end The moulding method chosen to produce moulded elastomeric sporting grips can have a substantial bearing on the economics of manufacture and the freedom of choice of structural features of the moulded grips

In Australian Patent Specification 80514/91 a prior art the "book" mould assembly was described as being a horizontal mould assembly comprising a lower section and upper section which was hinged to the lower section The core pin was of uniform diameter and the moulded hand grip formed by the horizontal mould assembly also had a uniform bore of uniform diameter The inventive aspect of Australian Specification 80514/91 is directed to a vertical mould assembly comprising a core pin which tapered outwardly from a free end or butt end thereof to a base part to produce a tubular hand grip of complementary shape

However the use of injection moulding processes for the use of hand grips is a very expensive proposition because of the large cost associated with production of the mould assembly comprising a core pin and a surrounding mould cavity which were usually formed from brass as well as the production of the injection head or nozzle This cost is exacerbated when it is desired to produce a hand grip having a spiral groove, spiral ridge or other form of surface pattern or indentation In this latter context production of mould cavities having a spiral groove, spiral ridge or other form of surface pattern or indentation is more expensive than production of mould cavities having a substantially plain internal surface and this is also the case in regard to production of core pins having a similar surface pattern or indentation in the case where the internal surface of the hand grip requires a corresponding surface pattern or indentation as in the case of the hand grip described in Australian Patent Specification 14426/83 Because of the great variation in the number of hand grips in regard to handle or shaft widths and lengths as well as cross-sectional shapes which are required for the different sports referred to above it will be appreciated that use of injection moulding processes for manufacture of hand grips for different sports would be a very expensive proposition because of the necessity of having different mould assemblies for hand grips for each sport as well as different injection heads or nozzles

SUMMARY OF THE INVENTION It is an aim of the invention to overcome or alleviate at least some of the problems associated with prior art moulded elastomeric sporting grips and methods for their manufacture

According to one aspect of the invention there is provided a moulded elastomeric sporting grip, said grip comprising - a generally tubular body having an opening at one end and a closure member at an opposite end, said tubular body including a parallel sided shaft receiving recess extending from said opening to adjacent said closure member, said grip characterised by the provision of a helically contoured outer surface simulating a helically wound tape extending in a clockwise direction from said closure member towards said opening, said helically contoured outer surface having a pitch of from 17mm to 22m and a pitch angle between 10° and 20°

Suitably the grip may comprise a cylindrical body with generally parallel sided outer wall surface

Alternatively said grip may comprise a frusto-conical body with an outer wall surface tapering from an enlarged butt end towards said opening

Preferably said pitch is from 18mm to 20mm, most preferably 19mm

Preferably said pitch angle is from 12° to 20°, most preferably 15°

Preferably the tackifier comprises a bleedable tackifier material Suitably the diametric difference between an adjacent zenith and nadir of said helically contoured surface is between 1 mm and 3mm

Preferably the diametric difference between said zenith and nadir

If required the elastomeric grip includes a tackifier material The elastomeric material suitably includes polymers selected from natural or synthetic rubber, co-polymers of natural and synthetic rubbers or thermoplastic resins

Natural rubbers have good tear strength, better resistance to heat accumulation and temperature fluctuation as well as good oil permeability Synthetic rubbers however are resistant to abrasion, oil and chemicals, and are easily tailored to a selected hardness Accordingly copolymers developed from a mixture of natural and synthetic rubbers to obtain the combined benefits of the natural and synthetic polymers

Natural rubbers and synthetic rubbers may be used at a volume ratio of 100% 0%, 75% 25%, 50% 50%, 75% 25% or 0% 100%, giving the grips made thereof desired softness and sponginess Hand grips made in accordance with the invention may also be resistant to abrasion and to oil and chemicals

A low cost filler may be incorporated into a polymer or a copolymer to increase the bulk and weight without changing the physical and structural characteristics of the said polymer or copolymer For example, carbon black may be used as a filler when the products must be black If the products must not be black, alternative fillers such as calcium carbonate, infusorial earth, clays, wood, flour, or magnesium carbonate may be used

Suitably said fillers may be used at rates of 10% to 50% of the total moulding material

A suitable plasticiser/tackifier may be incorporated into a polymer or copolymer The tackifier may impart tackiness so that the hand grips, when being fitted on a handle or shaft without use of any adhesives, will stick by fπctional engagement to the said hand grips or shaft and will not move Preferably however an adhesive is used to secure the grip to the shaft The tackifier may comprise a selectively bleedable plasticiser having a relatively low molecular weight and/or a simple molecular structure which permits controlled bleeding through the polymer matrix For example aliphatic petroleum oil may be used both as a plasticiser and as a tackifier at 10% to 15% of the filler loading Other suitable plasticisers and/or tackifiers may include mineral oils, tars, resins as well as mercaptobenzothiazole, dι(2-benzothιazolyl) disulphide or benzothiazole sulphonamide Vegetable oils including certain partially ozidizable vegetable oils such as castor oil, linseed oil and the like may also be used as a combination plasticiser/tackifier

A cross linking agent may be used to toughen a polymer or copolymer making the said polymer or copolymer more elastic without changing the softness and sponginess of the said polymer

For rubber polymers, the cross linking agents may be sulphur which may be used at 1 % to 2%, or zinc oxide which may be used at 0 75% A foaming or blowing agent may also be incorporated into the elastomer to obtain a cellular structure when cured

Pigments may be mixed into a polymer or a copolymer so that the said hand gπps may be produced in any colours so desired The said pigments may be fluorescent or non-fluorescent BRIEF DESCRIPTION OF THE DRAWINGS

Reference may be made to a preferred embodiment of the invention as shown on the attached drawings wherein

FIG 1 is an exploded perspective view of a mould assembly used in manufacture of grips according to the invention, FIG 2 is a perspective view of a bottom mould component utilised in the mould assembly of FIG 1 ,

FIG 3 is a schematic elevation of a compression press which may be utilised in the manufacture of the grips according to the invention,

FIG 5-7 show side elevational views of one embodiment of the invention adapted for use respectively as grips for a cricket bat, a hockey stick or lacrosse racquet and a table tennis bat

FIGS 8-10 show other embodiments of the invention adapted respectively for use with a golf club, a tennis racquet and a squash racquet FIG 11 illustrates a method of attaching hand grips of the invention to a handle or shaft of a sporting article

DETAILED DESCRIPTION OF THE DRAWINGS

In FIGS 1 -2 there is shown mould assembly 10 incorporating opposed mould members 11 and 12 each having opposed channelled recesses 13 and 14 In lower mould member 12 there are also incorporated core pins 15 wherein each core pin 15 is located concentrically in a corresponding mould cavity formed by recesses 13 and 14 Mould members 1 1 and 12 also have location or attachment apertures 16 for attachment to clamping plates (not shown) of supporting platens (not shown) of a compression press or transfer moulding press

In FIG 2 lower mould component 12 includes an attachment flange or ledge 17 (shown in phantom in FIG 1 ) which includes a plurality of attachment sockets or recesses 18 for retention of a corresponding tapered end 19 of core pins 15 Tapered ends 19 of core pins 15 may be releasably accommodated within sockets 18 by an interference fit or by screw threaded engagement Mould member 11 also includes ribs 20 which bound an associated arcuate groove 13 whereby each rib 20 includes an abutment surface 21 for abutment with corresponding abutment surfaces 22 of ribs 23 of mould component 12 which each bound an associated recess 14 Upper mould member 11 also includes a flange member 17a as shown in FIG 1 Flange member 17a forms a closure to the ends of the mould cavities formed by recesses 13, 14 when the mould is closed

The inner surfaces of recesses 13, 14 are contoured with a continuous spiral projection (not shown) to produce a hand grip simulating a continuous spiral tape wrap It will be appreciated from FIGS 1-2 that core pins 15 may be releasably attached from their associated mould member 11 to facilitate interchange with other core pins (not shown) to vary the wall thickness or change the cross sectional shape of the shaft recess in the hand grips so formed Similarly, inserts (not shown) may be used in conjunction with appropriate core pins to vary the length of the grip Contoured recesses

(not shown) in flange 17a permit the formation of end caps of complementary shape on the ends of the grips

FIG 3 shows a schematic elevation of a conventional compression press 24 used in compression moulding which may include a top housing 25 which may form a hydraulic reservoir, hydraulic piston 26, movable platen 27 and fixed platen 28 attached to base 29a Mould members 11 and 12 are clamped to respective platens 27, 28 Fixed uprights or mould pillars 29 provide guidance for movable platen 27

FIG 4 shows in elevation a schematic view of a transfer moulding press 30 which may be employed in association with the invention

Press 30 comprises an upper frame or bolster 32 fixed to upright frame members 36 and a lower frame or bolster 45 Slidably mounted on frame members 36 are an intermediate platen member 35 and a lower platen member 43 connected to hydraulic ram 44

Mounted on upper frame or bolster 32 is a top platen 33 having a plunger head 34 attached thereto Intermediate platen 35 includes a transfer chamber 37 with an orifice 37a in fluid communication with runner channels 38 formed in upper mould member 50, the channels 38 in turn in fluid communication with channelled recess 40 in which are located core pins 41 Lower mould member 51 includes corresponding recesses 42 which define the mould cavities when the mould assembly is closed With a mass of heated elastomer located in chamber 37, ram 44 is actuated and as it rises it first brings mould members 50, 51 together to close the mould assembly and as it continues upwards, plunger 34 enters chamber 37 to compress the elastomeric mass and force it into the mould cavities via runners 38 FIGS 5-7 show sporting grips formed in accordance with one aspect of the invention

FIG 5 illustrates a grip 60 for a cricket bat, FIG 6 illustrates a grip

61 for a hockey stick, lacrosse racquet or the like and FIG 7 shows a grip

62 for a table tennis bat In each case the grips are formed from a natural or synthetic rubber elastomer or copolymeπc mixture thereof and preferably include a lower molecular weight plasticiser such as di-octyl phthalate or di-isooctyl phthalate or a bleedable oil plasticiser which provides a slight tackiness to the surface of the grip Aliphatic and aromatic hydrocarbon products as well as vegetable oils may be used as plasticisers/tackifiers Castor oil, linseed oil and the like or modified vegetable oils will bleed for prolonged periods to provide a constantly tacky surface to the sporting grips whether made from natural or synthetic elastomers

The grips are generally cylindrical in shape and each includes a parallel sided smooth internal shaft receiving recess (not shown) An aperture 63 is provided in the end wall 64 of each grip to facilitate attachment to a shaft or handle of a sporting article

The outer surface of each grip 60, 61 , 62 is contoured to simulate a helically wrapped gripping tape typically applied to such sporting articles Significantly however, the direction of the simulated helical wrap is clockwise (starting from the butt end) as compared with all tape wrapped handles or shafts which extend counterclockwise (from the butt end)

Another significant departure from prior art tape wrappings is the pitch and pitch angle of the helix As shown in FIG 5 the pitch angle B is about 20° whereas that of

FIG 7 is about 18° Typically, the helical wrap, albeit in the opposite direction of golf clubs, tennis racquets and other sporting articles is around 30°

Yet another significant departure from prior art actual and simulated tape wrapping helices is the pitch of the helix Typically a fabric wrapping tape is about 40mm wide and is wrapped with a 30-40% overlap to give a pitch of between 25-30mm Simulated tape wrappings of moulded sporting grips have a similar pitch

It has been found that the combination of (a) helix direction

(b) pitch angle, and

(c) pitch of an actual or simulated helically wrapped tape grip is crucial to optimising grip comfort with a "natural" feel and resistance to axial and rotational slip

Trials conducted with cricketers, golfers, hockey players and tennis players have revealed that for optimum comfort and resistance to slip, a sporting grip should have a clockwise helical wrap simulation (when started from the butt end), a pitch angle of between 10° and 20° (preferably 5°) and a pitch of between 17mm and 22mm (preferably 19- 20mm) All players reported a remarkably "natural" feel to the grip without the sensation of a "knobbly" feel experienced with other non-slip grips

The grips possessed a "tacky" feel which enhanced the grip with a player's hand or hands even when hot and sweaty or in wet playing conditions This tacky feel persists for up to a year, even with constant use of the sporting article Other factors which affect a comfortable non slip grip are the cross section shape of the grip and the variation in thickness of the grip wall between the zenith 65 of a "wrap" and its adjacent nadir 66 simulating an overlap between adjacent wraps In practice, this difference is desirably in the range of 1 mm to 3mm, preferably 1 5mm As far as cross section is concerned, the grips of FIGS 5-7, while initially circular in cross section, adapt readily to the cross sectional shape of non-circular shafts or handles of sporting articles and also accommodate shafts or handles of non constant cross section in an axial direction FIGS 8-10 show variations of the embodiments illustrated in FIGS

5-7

FIG 8 illustrates a side elevation of a golf club grip having a body 67 closed butt end 68 and an open end 69 of smaller diameter Although the grip tapers outwardly towards butt end 68, the shaft receiving recess (not shown) is a parallel sided smooth bore cylindrical recess An aperture 70 is provided in the butt end 68 to facilitate attachment of the grip to a shaft (not shown)

FIG 9 is an end perspective view of a tennis racquet grip having a shaft receiving recess (not shown) with an octagonal cross section and parallel smooth inner walls

The body 71 has a smoothly contoured simulated helical wrap 72 with a generally octagonal cross section with a smooth transition between octagonal "faces" 73. The butt end 74 has a moulded octagonal shape and includes a fitting aperture 75.

FIG 10 is an end perspective view of a squash racquet grip having both an inner shaft receiving recess and an outer wall of generally oval cross sectional shape. For the sake of clarity FIG 10 employs the same reference numerals as FIG 9.

In all cases, the grips of FIGS 8-10 employ an external configuration of simulated tape wrapping in the same ranges described with reference to FIGS 5-7. In attaching the grips according to the invention to a parallel sided shaft or handle, it is generally sufficient to apply a small quantity of liquid adhesive around the butt end of the shaft or handle and then simply push the grip on firmly. The adhesive while wet acts as an adhesive and the aperture in the butt end of the grip allows air to escape therethrough. FIG 8 shows schematically the attachment of the hockey stick grip

80 of FIG 6 to the handle 81 of a hockey stick 82.

As the handle 82 is not of constant cross section along its length, a fine nozzle 83, attached to a hose 84, providing a source of compressed air, is inserted in the aperture 85 in the butt end 86 of the grip 80. As pressure is applied while holding the end 87 of grip 80 over the end 88 of the handle 81 , the grip 80 inflates and expands to accommodate the enlarged end 88 of the handle while the grip 80 is pushed axially thereover.

It will be readily apparent to a skilled addressee that many modifications and variations may be made to the invention without departing from the spirit and scope thereof.

For example, the outer surface of the grips may include projections or indentations to provide a textured surface to enhance either or both of appearance and non slip properties. During the moulding process, the butt end may include an end portion or indicia of a contrasting colour for advertising or identification purposes.

Claims

1 A moulded elastomeric sporting grip, said grip comprising - a generally tubular body having an opening at one end and a closure member at an opposite end, said tubular body including a parallel sided shaft receiving recess extending from said opening to adjacent said closure member, said grip characterised by the provision of a helically contoured outer surface simulating a helically wound tape extending in a clockwise direction from said closure member towards said opening, said helically contoured outer surface having a pitch of from 17mm to 22m and a pitch angle between 10° and 20°

2 A sporting grip as claimed in claim 1 wherein the grip comprises a cylindrical body with generally parallel sided outer wall surface

3 A sporting grip as claimed in claim 1 wherein the grip comprises a frusto-conical body with an outer wall surface tapering from enlarged butt end towards said opening

4 A sporting grip as claimed in any one of claims 1 to 3 wherein said pitch is from 18mm to 20mm

5 A sporting grip as claimed in claim 4 wherein said pitch is 19mm 6 A sporting grip as claimed in any preceding claim wherein said pitch angle is from 12° to 20°

7 A sporting grip as claimed in claim 6 wherein the pitch angle is 15°

8 A sporting grip as claimed in any preceding claim wherein the diametric difference between an adjacent zenith and nadir of said helically contoured surface is between 1 mm and 3mm

9 A sporting grip as claimed in claim 8 wherein the diametric difference between said zenith and nadir is 1 5mm

10 A sporting grip as claimed in any preceding claim wherein the elastomeric grip includes a tackifier material 11 A sporting grip as claimed in claim 10 wherein the tackifier comprises a bleedable tackifier material 12 A sporting grip as claimed in any preceding claim wherein the elastomeric material comprises polymers selected from natural or synthetic rubber, co-polymers of natural and synthetic rubbers or thermoplastic elastomeric plastics resins 13 A golf club grip according to any preceding claim 14 A tennis racquet grip according to any one of claims 1 to 12

15 A cricket bat grip according to any one of claims 1 to 12

16 A hockey stick grip according to any one of claims 1 to 12

17 A squash racquet grip according to any one of claims 1 to 12

18 A table tennis bat grip according to any one of claims 1 to 12