IES20050499A2 - Method of forming small stone articles and the articles formed by the method - Google Patents

Abstract

The invention concerns a method of forming beads of stone suitable for linking together to form rosary beads or the like, the method including forming longitudinal channels in thin stone blocks, wherein the distance between the cutting surface and the cutting blade during the channel formation may be adjusted by the insertion of thin sheets below the cutting surface at regular intervals during cutting so that the depth of the channels made in the blocks will remain constant during a production period.

Description

This invention relates to a method of forming small 5 stone articles and to the articles formed by the method. In particular, it relates to a method of forming stone beads which can be linked together to form rosary beads, necklaces, bracelets or the like.

The conventional method of forming stone beads suitable for linking together involves cutting stone slabs into thin blocks and forming longitudinal channels in two opposing phases of each block using a continuous rim diamond blade, and then cutting the channelled blocks into beads. When the channels are being cut, the diameter of the blade is fractionally reduced with each cut due to the abrasive nature of the process.

Accordingly, over a period of time, the depth of the channels being cut is also fractionally reduced to the same extent. The depth of the channels is critical. If they are too shallow, a linking chain cannot be held therein, and if they are too deep, the finished beads are likely to crack easily. At the current time, the cutting apparatus must be manually adjusted approximately every hour to compensate for the gradual reduction in the channel depth. However, it is very time-consuming to make an accurate adjustment that will ensure a constant channel depth with a consequent 11...... reduction in output.

It is an object of the invention to overcome the disadvantages of the prior art. ητα CL Ατδ Ζ i/ec IE 0 5 04 9 9 According to a first aspect of the invention, there is provided a method of forming small stone articles, especially beads suitable for linking together to form rosary beads or the like, the method comprising: (a) cutting a stone slab into thin blocks having at least two opposing faces; (b) placing the blocks on a cutting table comprising a cutting surface and a base; (c) forming a longitudinal channel in each of two opposing faces of each block using a cutting blade; and (d) cutting the channelled blocks obtained in step (c) into beads of the desired size; characterised in that for the channel formation in step (c) at least one sheet of material is inserted below the base of the cutting table at predetermined intervals so as to raise the height of the cutting surface and maintain the desired distance between the cutting blade and the cutting surface in use.

The stone slab used in the present invention preferably comprises marble, more preferably Connemara or Kilkenny marble, especially Connemara marble.

Preferably, from 1 to 6 sheets are inserted below the base of the cutting table at intervals of from 1 to 4 hours. More preferably, 2 sheets are inserted every hour during a production period. The sheets may be formed from any suitable material, preferably a plastics material such as polycarbonate or polyethylene terephthalate (PET). The sheets preferably have a thickness of from 50 to 100 μτη, preferably 75 μτη.

The thin blocks used in the present invention are preferably rectangular in cross-section, and more preferably square in cross-section. Each block preferably has a length of from about 75 mm to 200 mm, preferably about 100 mm. The cross-sectional area is preferably from about 7 mm x 7 mm to 9 mm x 9 mm, more preferably about 7.5 mm x 7.5 mm.

The channels are conveniently formed in the thin blocks using a continuous rim diamond blade. The depth of each channel is preferably from about 1 mm to 2 mm, more preferably about 1.5 mm.

The channelled blocks are cut into beads preferably having dimensions of 7.5 mm x 7.5 mm x 8 mm. The beads may be readily linked together by placing a chain or the like along the channels formed therein.

In a second aspect, the invention provides rosary beads or the like comprising beads of stone formed by the method of the invention.

The continuous rim diamond blade used in the present invention is preferably a 200 mm blade which rotates at approximately 3000 rpm. The cutting table is movable between an extended and retracted position and the cutting surface of the table is disposed below the blade in the retracted position. The blade is arranged IE 0 5 0499 to contact the block so that a channel of the desired depth, preferably about 1.5 mm, may be formed in the uppermost face of the block. The block is placed on the cutting surface when the table is in the extended position. The cutting surface is then moved in the direction of the blade by moving the table to the retracted position so that a channel may be formed in the block. The cutting table is returned to the extended position and the block is then turned over so that a channel may be formed in like manner in the opposing face thereof.

The depth of the channels cut in the thin blocks is critical. If they are too shallow, they cannot support a linking chain and if they are too deep, the finished beads will be weakened. Since the diameter of the cutting blade is fractionally reduced as each channel cut is made, the channel depth is correspondingly reduced. In accordance with the present invention and to overcome this problem, at least one sheet of material is placed below the base of the cutting table at regular intervals during the channel forming procedure so as to maintain a constant distance between the cutting surface and the cutting blade and, consequently, a constant depth of the channels being cut in the blocks. In this manner, the height of the cutting surface can be readily adjusted several times during a working shift so that the distance between the cutting surface and the blade remains constant throughout the working shift despite the ablation of the blade. Thus, a veneer of sheets is built up during a working shift. At the beginning of the each new working shift, the sheets may be removed and the blade height reset to the desired level.

The invention is illustrated in the following Example.

Example: Large blacks of Connemara marble were sawed into manageable pieces using a 1,200 mm wet diamond saw rotating at 1,000 rpm. These pieces were subsequently cut into smaller rectangular blocks using a 400 mm segmented diamond blade rotating at 2,000 rpm. The rectangular blocks were cut into slabs having a depth of 7.5 mm and a length of 100 mm. The slabs were then cut into thin blocks, each having a cross-sectional area of 7.5 mm x 7.5 mm. Each block was placed on a cutting table comprising a cutting surface and a base and movable between an extended and retracted position. In the latter position, the cutting surface is disposed directly below a 200 mm continuous rim diamond blade. Each block was placed on the cutting surface in the extended position. The cutting table was then retracted thereby bringing the block into contact with the cutting blade, the blade being arranged to contact the block so that a channel of 1.5 mm could be formed in the uppermost face of the block. The cutting table was returned to the extended position, the block was turned over and a channel was formed in the same manner in the opposing face of the block.

The 200 mm continuous rim diamond blade rotated at 3,000 rpm during the channel cutting. After every hour of cutting, two sheets (150 mm x 100 mm) formed from polyethylene terephthalate and having a thickness of 75 μτη were inserted below the base of the cutting table, thereby raising the height of the cutting surface by 1.5 mm during a ten-hour shift. In this manner, the distance between the cutting blade and cutting surface was maintained at a constant level throughout the cutting period and, consequently, the depth of the channels being cut also remained constant.

At the end of each working shift, the sheets were removed and the cutting blade was reset.

After cutting, the channelled blocks were then cut into beads having the dimensions 7.5 mm x 7.5 mm x 8 mm.

Such beads may be readily linked together by placing a suitable linking means, such as a chain, around the channelled beads.

The invention is not limited to the embodiment described herein which may be modified or varied without departing from the scope of the invention. ι?|Ε; IR ίΐι ·/; (/ (/, dts y v 4 & <4

Claims (5)

1. A method of forming small stone articles, especially beads suitable for linking together to form rosary beads or the like, the method comprising: (a) cutting a stone slab into thin blocks having at least two opposing faces; (b) placing the blocks on a cutting table comprising a cutting surface and a base; (c) forming a longitudinal channel in each of two opposing faces of each block using a cutting blade; and (d) cutting the channelled blocks obtained in step (c) into beads of the desired size; characterised in that for the channel formation in step (c) at least one sheet of material is inserted below the base of the cutting table at predetermined intervals so as to raise the height of the cutting surface and maintain the desired distance between the cutting blade and the cutting surface in use.

2. A method according to claim 1, wherein the stone slab comprises marble, especially Connemara or Kilkenny marble; and/or wherein from 1 to 6 sheets of a plastics material are inserted below the base of the cutting table at intervals of from 1 to 4 hours, preferably 2 sheets every hour, during a production period; and/or wherein each sheet has a thickness of from 50 gm to 100 gm, preferably 75 gm. . ,. IE 0 5 049 9

3. A method according to claim 1 or 2, wherein the thin blocks are rectangular in cross-section, each block having a length of from about 75 mm to 200 mm, preferably about 100 mm, the cross-sectional area being 5 from about 7 mm x 7 mm to 9 mm x 9 mm, preferably about 7.5 mm x 7.5 mm; and/or wherein the depth of each channel formed in the blocks is from about 1 mm to 2 mm, preferably about 1.5 mm; and/or wherein the channels are formed using a 200 mm continuous rim 10 diamond blade; and/or wherein each channelled block is cut into beads having dimensions of 7.5 mm x 7.5 mm x 8 mm.

4. A method according to claim 1, substantially as 15 herein described with particular reference to the accompanying Example.

5. Rosary beads or the like comprising stone beads formed by the method of any preceding claim.