GB2503752A

GB2503752A - Split colour manufacture of lawn bowling balls

Info

Publication number: GB2503752A
Application number: GB201215690A
Authority: GB
Inventors: Walter Benjamin Jacobs
Original assignee: MIDPIT Pty Ltd
Current assignee: MIDPIT Pty Ltd
Priority date: 2012-07-05
Filing date: 2012-09-03
Publication date: 2014-01-08
Also published as: ZA201206587B; GB201215690D0; NZ602210A; AU2012216568A1

Abstract

A method for manufacturing a lawn bowling ball with multiple distinct colours or finishes, comprising adding raw materials 130, 140 to a single cavity compression mould 100 divided by one or more separators 150, removing the separators 150, and stamping the raw materials 130, 140 using a plunger 120 to form a tablet 200. The method may further comprise preheating the tablet 200 to a doughy consistency, compression moulding the preheated tablet 200 to form a blank (200', fig 4), and machining the blank to form a finished lawn bowling ball (200", fig 5). Preferably the separators 150 can be removed from the mould 100 with minimal disruption to the raw materials to maintain a relatively sharp distinction between multiple colours or finishes. The separator 150 may be a planar, rigid sheet shaped to conform to the profile of the single cavity compression mould 100.

Description

SPLIT COLOUR MANUFACTURE OF LAWN BOWLING BALLS

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to co-pending patent applications having common inventor Walter Benjamin Jacobs and entitled "Precision Manufacture of Lawn Bowling Balls", and "Improved Lawn Bowling BaUs", the contents of both of which are hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to the manufacture of lawn bowling balls, aLso referred to as lawn bowls, or bowls.

BACKGROUND OF THE INVENTION

Lawn bowls are currently manufactured by heating powdered or granular rnelamine material, which is preheated to a putty-like or doughy texture. The preheated material is subjected to a compression load using a press (for example, a 150 ton press), which compresses the material, and excludes any excess gas and liquid from the mould. A blank results, which is machined to form the finished bowl.

Traditionally, lawn bowLs have been black in colour. Recent years have seen a trend towards coloured bowls, and more recently, speckled finishes have also been used. Furthermore, the use of various relief features -in addition to traditional grip rings -are also increasingly popular, and give bowls a distinctive and pleasing appearance. Typically, for example, a bowler's name, and perhaps team or other significant indicia are formed in relief in the surface of a bowl, and can be specified when ordering a set of bowls.

Consequently, there is a range of distinctive and personalised features that may be adopted when ordering a new set of bowls. A range of options are available in contrast to plain black bowls, which were the only option until quite recently.

Details of existing manufacturing techniques can be viewed in an episode of the How It's Made series, which is a product by the Science Channel, which is produced by Discovery Communications, LLC. How It's Made: Lawn Bowling Ball was published online 9 April 2010 by Discovery Communications, [C.

There is, n light of the foregoing, a need for a yet stiLl greater range of alternatives for distinctive appearing bowls, beyond the options presently available to bowlers.

SUMMARY OF THE INVENTION

The inventive concept resides in a recognition that a distinctive split-colour bowl can advantageously be manufactured using raw materials of different colours that, in the finished bowl, comprise opposing sides or halves of the bowl, by forming a tablet by compression moulding, in which raw materials of different colours are added to respective compartments temporarily defined within a single cavity compression mould, using one or more separator assemblies within the single cavity compression mouLd.

A blank for a lawn bowling ball is formed by subsequently preheating and compression moulding the tablet, which can then be suitably machined to form a finished lawn bowling ball.

Raw materials added to the cavity mould are arranged such that they are divided between separate compartments temporary defined within the cavity mould by one or more separator assemblies1 which are removed from the cavity mould prior to stamping the raw materials within to form the tablet. Removal of the temporary separator assembly preferably disrupts the raw materials but minimally, so that the contrast between the different colours or finishes is relatively clear.

For a simple spilt-colour pattern along the running surface of the bowl, the separator assembly is preferably a simple separator or divider of planar construction, shaped and adapted to the cavity mould. In this case, the separator or divider element that evenly divides the raw materials of different respective colours into opposed sides of the resulting tablet.

A simple split-colour pattern is adopted as this pattern is appealing and distinctive in appearance. A number of alternative patterns could of course be adopted using the same principles, using more and/or differently oriented compartments separating the single cavity compression mould. Separator assemblies of suitable configuration are thus designed to achieve an intended aesthetic result that is intended for the finished lawn bowling ball, and is thus limited only by imagination.

BRIEF DESCRIPTION OF DRAWINGS

Fig. I is a flowchart of steps involved in forming a blank for forming a lawn bowling ball having a split-colour pattern.

Figs. 2A and 2B are schematic representations (in cross-sectional and pLan views) of a compression moulding arrangement used to form a tablet of different colours.

Fig. 3 is a representation of a tablet having two distinctive colours, formed following stamping in a single cavity compression mould! schematica]ly represented in Figs. 2A and 2B.

Fig. 4 is a representation of a blank for a lawn bowling ball formed following compression moulding the tablet of Fig. 3.

Fig. 5 is a finished lawn bowling ball formed following machining operations on the blank of Fig. 4.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As referred to herein, raw materials in the form of melamine-based coloured granular materials are used, as supplied and widely available. Melamine is a thermosetting plastic compound, supplied in a raw granular state with a distribution of particle sLzes. Chemical additives are used to achieve different colours.

Lawn bowling can be manufactured, as referred to herein, with speckled finishes, typically in which a primary or dominant colour is flecked through with a secondary, and perhaps even a tertiary colour. Owing to the range of colours available, a large number of speckled finishes are available as determined by the ratios in which different coloured melamine raw materials are combined. The speckled finish is a consequence of the granular nature of the raw material. For the sake of expediency, speckled colour combinations are referred to herein as simply "colours" in the context of a split-colour pattern of a lawn bowling ball blank produced in accordance with the techniques described herein.

A process for producing a split-colour blank which is used for forming a lawn bowling ball following suitable machining operations is outlined in overview with reference to Fig. I. Desirably, the resulting blank is of close to a uniform density and is substantially free of internal cracks or fissures within the bulk of the blank.

First, raw materials are mixed, if need be, in step 10. This is desirabLe where a specked finish of the type described below forms one of the colours of the split-colour bowl.

Following any required mixing operations, raw materials are added to a single cavity compression mould in step 20. Raw materials of different colours are divided between separate compartments temporarily defined within the single cavity compression mould, as described in further detail below. The raw materials are then stamped within the single cavity compression mould into a tablet form, in step 30. The tablet so formed is preheated in step 40, prior to compression moulding proper. Compression moulding is performed in step 50, using the preheated tablets, to thus form lawn bowling ball blanks. Finally, the blanks can be suitably machined to form a finished lawn bowling ball in step 60.

The initial step 10 of mixing the raw materials is performed if one of the colours of the split colour bowl is to have a speckLed finish. Melamine granules are used as raw materials, and a desired ratio by weight of differently coloured melamine granules can be used to achieve different speckled appearances.

Mixing helps ensure a relatively uniform and random distribution of the differently coloured granules, which is aesthetically desirable. Mixing is of course unnecessary where a solid colour is used instead of a speckled finish.

Following any mixing operations that may be required, raw materials are added to a single cavity compression mould in step 20. Raw materials added to the single cavity compression mould are divided between separate compartments temporary defined within the single cavity compression mould by one or more separator assemblies, which are removed from the single cavity compression mouLd prior to stamping the raw materials within to form the tablet. For a simple split-colour pattern, a simple planar separator element can be used.

Figs. 2A and 2B depicts a suitable arrangement in schematic form. A cavity mould 100 has an internal space which defines the shape of the resulting tablet form. Compression moulding is performed by actuating a high pressure via a plunger 120, which is shaped to clear the profile of the cavity mould 100. Fig. 2A is a cross-section view, and Fig. 2B is a plan view, in which the plunger is removed from view.

This separator 150 may comprise a sheet of preferably rigid material, appropriately shaped and dimensioned to the cavity mould 100. when located in place, the raw materials can be added to the separate compartments defined within the mould by the separator 150. The separator 150, as the name implies, acts to separate the raw materials of different colours (indicated as 130, 140 either side of the separator 150), when added in granular form to the cavity mou]d 100.

Once the raw materials 130, 140 are added to these temporary separate compartments, the separator 150 is removed from the cavity mould lOt Preferably, the separator 150 is lifted vertically to disrupt the granular raw materiaLs in the single cavity compression mould only minimally, and ideally not at all, though this is not essential. Indeed, it may be desirable to retain an indistinct and ill-defined separation between adjacent colours to achieve different effects, achieved by disruption to the raw materials 130, 140 as the separator 150 is removed.

Once the separator 150 is removed, the raw materials can be subjected to a compression load of, for example, SOT, by the plunger 120 to thus form a tablet 200. The tablet 200 takes the form of the cavity mould 100.

The separator 150 is removed to assist thermosetting via crosslinking between the raw materials of different colours, which occurs subsequently to the tablet 200 being formed by application of heat and pressure, as described below in further detail.

Fig. 3 is a schematic representation of a tablet 200 formed of two contrasting colours evenly split between its two colours along a line of vertical orientation about its middle. The contrasting colours 130', 140' are the raw materias 130, 140, The tablet 200 has an elongate tablet or lozenge shape, characterised as having a generally elongate rectangular prismatic form, with soft rounded ends, as depicted in Fig. 4. Various alternative forms may be adopted with success.

The tablet 200, having being formed by compression load, is a solid mass.

The table 200 does not crumble upon light manual handling, but cannot tolerate rough handling.

The tablet 200 is then subjected to a preheating step 40, prior to compression moulding proper. As melamine is a thermosetting material, preheating is an appropriate step prior to compression moulding. The tablet 200 is preheated using any suitable technique, though radio frequency heating is preferred. A radio frequency heater of any suitable construction can be used.

Preheating helps to remove residual moisture that may be present in the tablet following formation, and desirably provides a substantially uniform temperature throughout the tablet 200. Temperatures of approximately 100°C to 110°C are found to be suitable for preheating, though temperatures outside this range can also yield satisfactory results.

Preheated tablets 200 are transferred while heated to a compression mould, and moulded under pressure (for example, 150T) to form a blank 200', as depicted in Fig. 4, and having multiple colours 130', 140" corresponding with raw materials 130, 140. Bowls are supplied in sets of four, and for expediency and efficiency, a set of four preheated tablets 200 are transferred in rapid succession to respective cavities of a four-way compression mould, which are then compressed. Following compression moulding, the blanks 200' are removed, and any excess flash removed. The fresh blanks 200' are placed preferably in an insulating environment that encourages the blanks 200' to maintain their stored heat for an extended period. This facilitates curing of the blank 200', namely thermosetting via crosslinking.

The blanks 200', as depicted have a spigot which assists in machining operations, which are not further described herein. Machining operations result in a finished bowl 200", as depicted in Fig. 5, having multiple colours 130", 140".

The contrast between the split colours is desirably crisp and clear. The granular nature of the raw materials, however, means that the split may not be necessarily be sharply defined. The split colours mix to some extent, owing to a number of factors.

First, following removal of the separator, there is some minimal amount of disruption to the raw materials occurs within the cavity mould. Second, the compression load compresses the raw materials, and inevitably moves the raw materials to some extent beyond the boundaries or divisions created by the separator. Third, the thermosetting curing process brought about by the application of heat and pressure Needs the colours into each other to some extent.

The above factors notwithstanding, the contrast between the split colours is relatively defined at its edges, but may comprise some jagged edge definition and/or tonal graduation. A split between colours is however achieved.

While a split colour pattern as described and depicted is preferred, a range of other patterns may be adopted. For example, a two tone bowl may be configured such that the contrasting colours are split in a different orientatiort Similarly, a tripartite or striped pattern may be adopted, in which the running surface is a first colour, and the lateral sides of the bowl are a second colour, or second or third colours. Patterns of this type can be used to depict national or team colours. Such patterns require, of course, three separate temporary compartments defined by the separator assembly or assemblies.

Furthermore, a variety of other multiple colour configurations can be adopted as required. A range of separator assemblies may be experimented with to achieve a broad variety of different effects. Beyond relatively simple, geometric patterns, more arbitrary patterns with less sharply defined demarcations between colours may also be developed.

Claims

CLAIMS: 1. A method for forming a tablet suitable for preparing a blank for a lawn bowling ball having multiple distinct colours or finishes, the method comprising: adding raw materials to a single cavity compression mould, divided between separate compartments temporary defined within the single cavity compression mould by one or more separator assemblies; and stamping the raw materials within the single cavity compression mould to form a tablet suitable for forming a blank for a lawn bowling ball, following removal of the one or more separator assemblies prior to stamping.
2. A method according to claim 1, wherein the one or more separator assemblies can be removed from the single cavity compression mould, once raw materials are added to the mould, with minimal disruption to the raw materials thereby maintaining a relatively sham distinction between the multiple colours or finishes.
3. A method according to any one of claims 1 or 2, wherein the one or more separator assemblies is a sheet of planar, rigid construction shaped to substantially conform to the profile of the single cavity compression mould across the mould.
4. A method according to any one of claims 1 to 3, wherein the single cavity compression mould is of elongate form and having rounded ends.
5. A method according to any one of claims 1 to 4, further comprising preheating the tablet formed by use of the single cavity compression mould; compression moulding the preheated tablet to form a blank for a lawn bowling ball; and machining the blank to form the lawn bowling ball.
6. A tablet suitable for preparing a blank for a lawn bowling ball having multiple distinct colours or finishes, formed according to the method of any one of the claims ito 5.
7. A blank for a lawn bDwling ball having multiple distinct colours or finishes according to the method of any one of the claims ito 5.
8. A lawn bowling ball having multiple distinct colours or finishes according to the method of any one of the claims 1 to 5.