GB2293570A

GB2293570A - A stonecutting tool

Info

Publication number: GB2293570A
Application number: GB9419450A
Authority: GB
Inventors: Brian George Baker
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-09-27
Filing date: 1994-09-27
Publication date: 1996-04-03
Also published as: GB9419450D0; DK105895A

Abstract

A stonecutting tool comprises a disc shaped member 1 of a composite material with a cutting edge 2. The major part of the tool is made from a base material 3 of metal ore e.g. a nickel or cobalt alloy. Located within the composite material are areas 4 of hard metal grams of wolfram carbide, which surface at the cutting edge 2 and stand proud of the base material 3. Also located within the composite disc 1 are segments 5 of a relatively hard alloy interspersed with diamond grains 6 measuring 0.1 to 0.5 mm in outside dimension. During wear of the disc 1 the diamond grains become exposed at the tool cutting edge 2. The stonecutting tool may be manufactured utilizing diamond grains recovered from scrap diamond tipped sawblades. <IMAGE>

Description

AN IMPROVED STONECUTTING TOOL AND A METHOD OF MANUFACTURING SAME This invention relates to an improved stonecutting tool and to a method of manufacturing same.

More particularly the tool is used for the facing, cutting and milling of natural stone.

Conventional tools for the cutting and milling of natural stone are made of a base material in which natural or synthetic diamonds are included to carry out the stonecutting process. The base material is normally a metal ore, e.g. a nickel or cobalt alloy and the diamond content is relatively small, i.e. between 1 to 10%.

When the tool wears, new diamonds are presented to the workpiece. To obtain a longer working life of the tool, it is of importance that the exposed diamonds are not torn out of the base material.

An aim of the present invention is to provide an improved tool construction leading to a longer life of the tool, and to a method of utilising worn diamond tips from sawblades to manufacture the improved tool.

According to one aspect of the present invention there is provided a stonecutting tool comprising a base material of metal ore with areas of hard metal grains arranged to project from the tool cutting edge and a series of base material segments of a relatively hard alloy interspersed with diamond grains which are exposed at the tool cutting edge, wherein the areas of hard metal grains project from the tool cutting edge to stand proud of the base material but less than the outer edge of the diamond grains.

Conveniently, the metal ore of the base material is a nickel or a cobalt alloy.

Preferably, the areas of hard metal grains are wolfram carbide.

In a preferred construction the diamond grains are recovered from the diamond tips of used sawblades.

According to a second aspect of the present invention there is provided a method of recovering diamond tips from worn sawblades by crushing the diamond tips to a size between 2 to 8mm, mixing them with 10 to 20% wolfram carbide grains measuring,between 1 to 3mm, filling the spaces between the diamond grains with a silver alloy and incorporating the mixture of diamond grains, wolfram carbide grains and silver alloy in the cutting edge of a stonecutting tool.

In the preferred method the silver alloy is that used for brazing metals.

An embodiment of an improved stonecutting tool, according to the invention will now be described, by way of example only, together with a method of manufacturing the tool, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side elevation of a stone cutting tool, and Figure 2 is an enlarged fragmentary view of the Part A ringed in Figure 1.

The improved stonecutting tool is in the form of a disc shaped member 1 of a composite material with a cutting edge 2. The major part of the tool is made from a base material 3 of metal ore, e.g. a nickel or cobalt alloy. Located within the composite material are areas 4 of hard metal grains of wolfram carbide, which surface at the cutting edge 2 and stand proud of the base material 3, as shown in the enlarged fragmentary view of Figure 2.

Also located within the composite disc 1 are segments 5 of a relatively hard alloy interspersed with diamond grains 6 measuring 0.1 to 0.5mm in outside dimension. During wear of the disc 1 the diamond grains become exposed at the tool cutting edge 2.

In operation, as the tool is rotated the base material 3 is removed when abrading against the stone workpiece (not shown). The wolfram carbide grains of the areas 4 are exposed at the tool cutting edge 2 and are abraded by the stone workpiece but because the wolfram carbide is harder than the base material, which is made of a softer silver alloy, the wolfram carbide grains will protrude above the surface of the base material but below the exposed cutting diamonds. In this way the wolfram carbide grains form a support for the tool because they carry a portion, approximately 5%, of the applied force on the tool.

If too great a feed is applied to the cutting tool when using conventional tools, or the tool spindle vibrates, which is often the case, the diamond grains can easily be torn out of the base material and lost. With the improved tool of the present invention, the wolfram carbide grains support the tool, thus protecting the diamond grains from excessive loads and preventing them from being torn from the hard alloy base in which they are set.

Because the wolfram carbide grains are more than ten times larger than the diamond grains, they can withstand any overloading. Tools made according to the invention have a greater life and are capable of removing more material than conventially made tools.

The invention also includes a method of utilizing diamond grains from scrap diamond tipped saw blades. When diamond tipped saw blades become worn, the segments containing the diamonds are replaced while there are still 2 to 3mm of the segments left. New diamond segments, measuring e.g. 8x26x30mm when they are brazed on the tips of a large circular saw blade, are used for cutting slabs of stone.

When the segments are due to be replaced they usually measure only a few millimeters thick. These worn segments can be purchased relatively cheaply and are manufactured for use in the stonecutting tool of the present invention by crushing them into grains measuring 2 to 8mm in outside dimensions and mixing them with 10 to 20% of wolfram carbide grains measuring between 1 to 3mm in outside dimensions. The spaces between the grains are filled with a metal alloy, e.g. a silver alloy normally used for brazing metal.

The use of the manufactured crushed diamond segments has the following advantages, The base material of the segments is relatively hard e.g., nickel or cobalt alloy, while the base material of the tool is a much softer material and is therefore easily abraded by the sludge and the particles of stone from the workpiece. Thus there is more room for the passage of water for cooling the tool cutting edge and workpiece a well as transportation of the sludge between the tool and workpiece.

Claims

1. A stonecutting tool comprising a base material of metal ore with areas of hard metal grains arranged to project from the tool cutting edge and a series of base material segments of a relatively hard alloy interspersed with diamond grains which are exposed at the tool cutting edge, wherein the areas of hard metal grains project from the tool cutting edge to stand proud of the base material but less than the outer edge of the diamond grains.

2. A stonecutting tool as claimed in claim 1, wherein the metal ore of the base material is a nickel alloy.

3. A stonecutting tool as claimed in Claim 1, wherein the metal ore of the base material is a cobalt alloy.

4. A stonecutting tool as claimed in any preceding claim, wherein the areas of hard metal grains are wolfram carbide.

5. A method of recovering diamond tips from worn sawblades by crushing the diamond tips to a size between 2 to 8mm, mixing them with 10 to 20% wolfram carbide grains measuring between 1 to 3mm and filling the spaces between the diamond grains with a silver alloy and incorporating the mixture of diamond grains, wolfram carbide grains and silver alloy in the cutting edge of a stonecutting tool.

6. A method as claimed in claim 5, wherein the silver alloy is that used for brazing metals.

7. A stonecutting tool substantially as hereinbefore described with reference to and as shown in the accompanying drawing.

8. A method of manufacturing a stonecutting tool substantially as hereinbefore described with reference to and as shown in the accompanying drawing.

8. A method of recovering diamond tips from worn sawblades substantially as hereinbefore described with reference to and as shown in the accompanying drawing.

Amendments to the claims have been filed as follows 1. A stonecutting tool comprising a base material of metal ore with areas of hard metal grains arranged to project from the tool cutting edge and a series of base material segments of a relatively hard alloy interspersed with diamond grains which are exposed at the tool cutting edge, wherein the areas of hard metal grains project from the tool cutting edge to stand proud of the base material but less than the outer edge of the diamond grains.

5. A method of manufacturing a stonecutting tool as claimed in any preceding claim, wherein diamond tips are recovered from worn sawblades by crushing the diamond tips to a size between 2 to 8mm, mixing them with 10 to 20% wolfram carbide grains measuring between 1 to 3mm and filling the spaces between the diamond grains with a silver alloy and incorporating the mixture of diamond grains, wolfram carbide grains and silver alloy in the cutting edge of a stonecutting tool.