AU6411000A - Method for making a bat - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "METHOD FOR MAKING A BAT" The following statement is a full description of this invention, including the best method of performing it known to me:

TITLE

"METHOD FOR MAKING A BAT" FIELD OF THE INVENTION THIS INVENTION relates to a method for making a sports bat and, in particular, externally reinforcing a wooden core to produce a baseball bat, softball bat or similar.

BACKGROUND ART Traditionally, bats for games have been made from wood.

With improved technology, other materials and methods have been used 10 for producing sports bats. Aluminium, rubber and synthetic resins have been used to produce bats. These materials have, at times, overcome deficiencies in the wooden bats, such as excess weight and tendency to breakage. Construction methods, such as laminating have also been used in an attempt to produce a lighter, stronger bat. However, wooden bats have never been entirely displaced and, in some aspects, retain advantages over other material.

This is particularly the case in baseball, wherein the application of modern technology, particularly in the form of aluminium bats, has led to a distribution of advantage between a pitcher and a batter which tends to favour the latter. Improved weight distribution, shock absorption and energy transfer has meant that the modern aluminium baseball bat allows a batter to propel a struck ball faster and further. This also has a serious safety effect in that the time from when a baseball leaves a pitcher's hand until its return to the pitcher, if struck in his or her direction is faster than human reaction time. This means the pitcher is vulnerable to high speed impact from the ball without being able to use any defensive reflexes. As a result, various baseball governing bodies have introduced laws that bats must be predominantly of wooden construction.

This has highlighted the problems of bats breaking, particularly in baseball where the shape of the bat demands a narrowed handle with resulting potential fracture points below the barrel or hitting region of the baseball bat. Wooden bats are prone, therefore, to 10 breakage in use and are also reasonably expensive to purchase.

o oo *US Patent No 5,904,803 discloses a method of reinforcing a wooden core with a continuous sleeve of high-strength fibres which are ooo* resin bonded to substantially the whole of the core's outer surface. The •ooo method is based on a heat shrinking heater capable of moving along a preformed bat assembly to shrink thermoplastic tubing into a mould for the bat. Subsequently, resin is forced, under pressure, to wet fibreglass sleeve layers in the preformed bat assembly while encapsulated in the heat shrunk plastic mould. Finally, the mould is removed once the resin has cured. This method involves relatively complex steps to ensure close apposition between a fibreglass sleeve and a wooden bat core. It also requires expensive and mechanically complex equipment, such as moving heaters and pressure devices.

OBJECT OF THE INVENTION It is an object of the invention to provide a useful alternative to known methods for applying external reinforcement when making a bat.

SUMMARY OF THE INVENTION In one form,. the invention resides in a method of making a bat, said method comprising the steps of: forming a bat by applying a fibrous material and a curable resin to substantially the whole of the exterior surface of a core; inverting a resilient tube over the bat, thereby compressively enveloping the bat in the tube; allowing the resin to cure; and •oooo 10 removing the resilient tube.

oooo The bat may be a baseball bat.

Preferably, the fibrous material is a braided material.

Suitably, the braided material is a fibreglass material. Preferably, the fibrous material is a sleeve. The curable resin is preferably an epoxy resin.

"The core may suitably comprise wood. Alternatively, the core may comprise a synthetic material.

The resilient tube may comprise rubber or latex. The resilient tube may be configured as an elongate balloon. The resilient tube may have an aperture in its wall. The aperture may have a resiliently reinforced periphery. The aperture may be dimensioned so as to require stretching to slide along the baseball bat, thereby providing a compressive force.

The method preferably includes the step of: inflating the resilient tube prior to inverting it over the bat.

Inflating the resilient tube may suitably be accomplished by introducing pressurized air into an internal cavity of the tube.

Alternatively or additionally, liquid may be introduced into the internal cavity. Air of fluid may be introduced into the resilient tube through the aperture.

The method may further include the step of: releasing pressure in the tube by releasing air or liquid from the internal cavity of the tube when air or liquid is displaced during the oo•°• 10 inversion of the resilient tube over the bat.

oooo ~BRIEF DESCRIPTION OF THE DRAWINGS o FIG. 1 is a side sectional view of an arrangement at the starting point of the method of the invention.

FIG. 2 is a side sectional view of the arrangement of FIG. 1 00 with the method further advanced.

gong FIG. 3 is a side sectional view of the arrangement of FIGS.

1 and 2 wherein the method of the invention is yet further advanced.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to FIG. 1, a shaped baseball bat 10 (in production) comprises a wooden core 11 and at least one outer layer 12 formed from a sleeve of fibrous, conforming material. The material is preferably fibreglass and is in a braided form with strands generally perpendicular to each other and at approximately 450 angle to the longitudinal axis of the wooden core 11.

6 The baseball bat 10 has a barrel region 13 and handle region 14. The wooden core 11 may be slightly less than the required dimensions of the finished bat 10 to allow for the thickening effect of the outer layer 12. The inventor has found that a suitable undersize of the wooden core is approximately 2 mm on all surfaces.

Prior to applying the material sleeve, the wooden core 11 may be wetted with epoxy resin. Preferably, the epoxy resin is of a high grade quality, such as aircraft grade. An example of such a product is Araldite LC3600, produced by Ciba. This is a specifically formulated ooooo low viscosity Di-Functional Resin which is used with a hardener, preferably a formulated Polyamine Adduct. The epoxy resin may be :::applied with a brush. The braided material is preferably located over a hollow tube (not shown) whose inner diameter is slightly larger than that of the barrel region 14 of the wooden core and whose length is preferably ooooo longer than bat 10. The wooden core 11 may then be located inside the tube which is then removed from contact with the braided sleeve. While removing the tube, the braided sleeve can be fed off one end of the tube and into contact with the wooden core 11. The braided tube may then be manually shaped to conform to the wooden core 11. The braided sleeve is preferably then wetted again with resin which is applied with a brush.

The braided material sleeve preferably has a diameter slightly less than that of the barrel region 13. The sleeve is applied over the full length of the wooden core 11. The sleeve may stretch slightly to conform to the barrel region 13 and may then be moulded into close conformation in the handle region 14. This moulding may be done manually. In the process of moulding, the angle between strands of the fibrous material may change so that the strands are more longitudinally oriented in relation to a central longitudinal axis of the bat whereas the angle between strands in the barrel region 13 is substantially unchanged.

The baseball bat 10 is preferably supported on a spike located in a resin collecting vessel 16 so that any excess resin from the procedure is collected in the resin collecting vessel 16 for subsequent use.

10 A resilient tube 17 may be inflated with air 18 and brought o into contact with the handle end 19 of baseball bat 10. Although the S•resilient tube 17 is described as inflated with air, it may be distended by any suitable means. For example, the resilient tube 17 may be inflated with liquid, such as water. Further alternatively, the resilient tube may not be inflated at all but may simply be stretched onto the baseball bat 10 by outward and downward directed pressure.

FIG. 2 shows the process continuing in that the resilient tube 17 has been forced further down the baseball bat 10 and, in the process, is creating a close-fitting, pressurised skin 20 closely adjacent the outer layer 12 of baseball bat 10. Excess resin 21 is forced ahead of the anterior curve 22 of resilient tube 17. The resilient tube 17 is inverted or turned inside out, at least in part, by the process of application so that its initial external surface 23 becomes internalised by the invagination 24 formed as the bat 10 is enveloped by the resilient tube 17.

8 FIG. 3 shows the baseball bat 10 fully encapsulated in resilient tube 17 with exterior skin 20 closely adjacent virtually all the exterior surface of baseball bat 10 other than at the point of contact between spike 15 and baseball bat 10. Excess resin 21 has been captured in resin collecting vessel 16. It is possible to recycle the resin before it cures to a point of being unworkable. The air 18 may be released from resilient tube 17 through aperture 25 as the baseball bat is enveloped during the procedure in order to avoid excessive pressure on the bat or rendering the process unwieldy. The resilient tube 17 may 10 be left as a double layer on the baseball bat 10 or, alternatively, may be **fed over the baseball bat 10 so that only a single layer of the resilient material is left in contact with the outer layer 12 of the baseball bat 10. In this process, a resiliently reinforced periphery 26 of aperture 25 may be slid over the bat. The periphery 26 is preferably dimensioned to require stretching while it is slid over the bat.

The baseball bat with covering skin 20 is set aside for an appropriate curing time for the epoxy resin used. The outer skin formed by resilient tube 17 is then removed to leave an outer layer of cured, epoxy resin-impregnated material bonded to the central wooden core 11 to produce an externally reinforced baseball bat.

The resilient tube 17 may suitably be made of latex. The shape of the resilient tube 17 may be in the form of an elongate balloon.

The air inlet aperture may have a reinforcing ring of resilient rubber. If so, the reinforcing ring may be rolled down the baseball bat 10 as a final 9 pressurising constriction during complete inversion of the balloon-like resilient tube 17. The increased pressure of this passage may cause any further excess resin to be expelled.

In a further embodiment, the invention may reside in a method of making a bat wherein an elongate tube is inverted by rolling it down the bat without prior inflation. The bat may be brought into contact with the tube and the tube may then be advanced with a rolling action which will invert the tube or turn it inside out as it is advanced.

The inventor has found that thermoset epoxy resins which Goo$*: a self-cure at or near room temperature are most suitable for this 0...00 procedure. It is clear to a skilled addressee that the curable resin must be chosen for its adhesive qualities as well as fracture and impact #Goo resistance and ability to dissipate energy. A range of suitable products too* will be known to such an addressee. The epoxy resin chosen is

S..

preferably clear to highlight the wooden core 11 of the baseball bat although this is not essential. The wooden core may be made from Northern White Ash timber.

The braided material may suitably be a fibreglass braid and formed as a sleeve on a continuous roll for easy use during production.

An end of the sleeve may be neatly finished on the handled end 19 prior to application of the resilient tube 17. Finishing of the barrel end 27 will occur as a result of the movement of resilient tube 17 past the barrel end 27. Although the method has been described as commencing at the handle end 19 and proceeding to the barrel end 27, it may be performed in the reverse direction.

Although the bat has been described as a baseball bat, it is clear that the technique may be applied to other types of bats, such as softball bats, cricket bats or other suitable types of bats. Although the core has been described as wood, it is clear that other materials, such as rubber or synthetic substances like plastics or Styrofoam may form the core.

From the foregoing description, it should be apparent that the invention encompasses an advantageous advance in the art. Further, ooooo 10 it should be clear that the invention may be embodied in other specific forms without departing from the spirit of the essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

oooe• ooo

Claims (8)

1. A method of making a sports bat comprising the steps of: forming a bat by applying a fibrous material and a curable resin to the exterior surface of a core; inverting a resilient tube over the bat, thereby compressively enveloping the bat in the tube; allowing the resin to cure; and removing the resilient tube.

2. The method of claim 1 further including the step of inflating 10 the resilient tube prior to inverting it over the bat. ooooo

3. The method of claim 2 further including the step of releasing pressure in the tube during inversion of the tuber over the bat.

4. The method of claim 1, wherein the fibrous material is a S°braided fibreglass material.

5. The method of claim 1, wherein the curable resin is an epoxy resin.

6. The method of claim 1 including the step of applying a compressive force to the bat by sliding an aperture of the resilient tube along the bat.

7. A bat when made according to any one of the methods of claims 1 to 6.

8. A method of making a bat substantially as herein described with reference to the figures. DATED this Ninth day of October 2000. PAUL HANSON By his Patent Attorneys FISHER ADAMS KELLY