Method of manufacture of a lawn bowl

Abstract

A method of manufacturing a lawn bowl 10 includes the steps of placing cold melamine moulding compound granules into a pre-mould in layers 11, 12, 13, 14, 15 of different colours and / or textures, sha

Description

This invention relates to the manufacturing of lawn bowls. Background to the invention The sport of lawn bowling is popular around the world. A lawn bowl is a ball of solid material which is designed to be bowled along a vector. The vector is transverse to the axis of the lawn bowl, which axis is normally indicated on the ball with a spot or small ring. The centre of gravity is offset to the axis, called a bias, which causes the trajectory or path of the bowl to be curved relative to the bowling direction. The location of the centre of gravity varies within a set of bowls. One or preferably two grip rings are normally provided to help a bowler to locate his hand correctly and consistently on the ball and to provide some grip when launching and releasing the bowl. The applicant is aware of the technique of moulding bowls from melamine compound. Typically the melamine moulding compound in the form of granules is preheated in a container into a putty and the container shaped putty is then placed in a ball shaped mould and then hydraulically pressed into a ball shaped blank. Typical pressures used to press preheated is 150 tons. The moulding compound often includes pigments to give colour to the bowl. The blank is then machined on a CNC combined Milling machine into its final lawn bowl shape. Different coloured granules can be placed in the mould to produce a lawn bowl with different colours. It is an object of the invention to provide a bowl with improved and variable colour aesthetics. General description of the invention According to the invention there is provided a method of manufacturing a lawn bowl, which includes the steps of: placing cold melamine moulding compound granules into a pre-mould in layers of different colours and / or textures; shaping one or more layers along the contact surface of the granules and wall of the mould to produce the desired design; pressing, at about about 150 ton, the moulding compound layers in the pre-mould the layers to form a pre-shaped block; placing the block into a pre-heater at about 85 to 95 degrees Celsius for 80 to 100 seconds; placing the pre-heated block into the final 4 cavity mould, heated to about 145 degrees Celsius and pressing the block at 180 tons or higher to form a lawn bowl blank; and machining the blank to form a lawn bowl wherein the shape of the layers are represented along the surface of the lawn bowl. Moulding compound granule texture may include granule size, granule size distribution, mixed colour granules and the like. The layers may preferably be orientated transverse to the axis of the lawn bowl. The layers may be shaped, for example, into swirl, wave, zig zag or similar shapes. The layers may be carefully shaped into custom shapes. A shaping tool may be used to shape the layers or the interface between layers. The tool may be of a flat sheet and flexible to allow it to curve along the surface of the mould and provided with a shape along one edge thereof. The tool may be configured to press, scrape, keep or otherwise shape the granules, surface of the granules or interface between layers of granules. The granules may be ground to a finer coarseness before use to provide a fine sharp line between different colours. The invention also extends to lawn bowls manufactured by the method described above. The invention is to be applied to lawn bowls in sizes 000,00,0,0.5,0,1,1.5,2,2.5,3,3.5,4,4.5 and 5. Detailed description of the invention The invention is now described by way of example with reference to the accompanying drawings. In the drawings: Figure 1 shows a front view of a bowl, in accordance with the invention; and Figure 2 shows a number of embodiments using different base and swirl layer colours and texture variations, in accordance with the invention. Referring now to the drawings, the bowl, in accordance with the invention, is generally indicated by reference numeral 10. In this example, the bowl 10 is manufactured from Melamine. The bowls are moulded and then machined on a lathe combined / milling machine. The method of manufacturing the lawn bowl 10 includes the step of placing cold melamine moulding compound granules into a pre-mould in layers of different colours and / or textures mould to be preformed in a pre moulding press in 5 layers 11, 12, 13, 14, 15 of different colours. After the first layer 11 is placed in the mould, it is shaped with a flat flexible sheet tool (not shown), with a zig zag shape along one edge 20 thereof, along the contact surface of the granules and wall of the mould (not shown). The next layer 12 is placed onto the first layer 11 and the layer 12 is shaped with the tool and so on up to the fourth layer 14 and the final layer 15 is placed on top. The moulding compound layers in the premould the layers are pressed to form a pre-shaped block. The block is placed into a pre-heater at 90 degrees Celsius for between 90 and 97 seconds depending on the colour mix. The pre-heated block is placed into the final 4 cavity mould and the block is pressed at 200 tons at 145 degrees Celcius to form a lawn bowl blank (not shown) and the blank is machined to form a lawn bowl 10 wherein the shape of the layers 11, 12, 13, 14 and 15 are transverse to the axis and are represented along the surface of the lawn bowl 10. Material Melamine Weight 1.85 KGS to make the blank Pre Heating the pre form for the moulding to 90 degrees Temp 145 Celsius is moulding temp Curing / Cycle time 10 mins Pressure 200 ton using a 4 cavity mould Cooling in a controlled environment 48 hours This process is the complete Blank which then goes to the Robots as per the video on our website to make the complete bowl in the various sizes and grips. Figure 2 shoes a number of lawn bowls wherein the colour and texture of the swirls shaped layers are varied to give the different aesthetically pleasing patterns on the surface of the lawn bowl. It shall be understood that the example is provided for illustrating the invention further and to assist a person skilled in the art with understanding the invention and is not meant to be construed as unduly limiting the reasonable scope of the invention. It is to be understood that there are numerous variations and designs possible within the scope of the invention.

Claims

1. A method of manufacturing a lawn bowl, which includes the stepsof:placing cold melamine moulding compound granules into a pre-mould in layers of different colours and / or textures;shaping one or more layers along the contact surface of the granules and wall of the mould to produce the desired design;pressing, at 140 to 160 ton, the moulding compound layers in the pre-mould the layers to form a pre-shaped block;placing the block into a pre-heater at about 85 to 95 degrees Celsius for 80 to 100 seconds;placing the pre-heated block into the final 4 cavity mould, heated to 140 to 150 degrees Celsius and pressing the block at between 170 to 190 tons or higher to form a lawn bowl blank; andmachining the blank to form a lawn bowl wherein the shape of the layers are represented along the surface of the lawn bowl.

2. A method as claimed in claim 1, wherein the moulding compound granule texture is selected from one or more of granule size, granule size distribution, and mixed colour granules.

3. A method as claimed in claim 1 or claim 2, wherein the layers are orientated transverse to the axis of the lawn bowl.

4. A method as claimed in any one of claims 1 to 3, wherein the layers are shaped into swirl, wave, zig zag or similar shapes.

5. A method as claimed in any one of claims 1 to 3, wherein the layers are carefully shaped into custom shapes.

6. A method as claimed in any one of claims 1 to 3, wherein a shaping tool is used to shape the layers or the interface between layers.

7. A method as claimed in claim 6, wherein the tool is of a flat sheet and flexible to allow it to curve along the surface of the mould and provided with a shape along one edge thereof.5 8. A method as claimed in claim 6, wherein the tool is configured to press,scrape, keep or otherwise shape the granules, surface of the granules or interface between layers of granules.

9. A method as claimed in any one of claims 1 to 8, wherein the granules are 10 ground to a finer coarseness before use to provide a fine sharp line between different colours.

10. A lawn bowl manufactured by the method as claimed in any one of claims 1 to 9, which includes a pattern or shape on the surface of the bowl.15

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