ZA984831B - Wire saw - Google Patents

Description

i : 184831

BACKGROUND OF THE INVENTION

This invention relates to a wire saw such as that used for cutting stone, concrete and the like.

Wire saws are known in the art and comprise a wire rope having a plurality of spaced sleeves located on the rope and bonded thereto. The sleeves generally comprise a metal or like matrix having a mass of abrasive particles such as diamond or cubic boron nitride uniformly dispersed therein. Fach abrasive sleeve presents an abrasive cutting edge.

EP 0 317,963 discloses such a wire saw which includes, in addition, a layer of elastic material of rubber which surrounds the wire rope between the : abrasive sleeves. This elastic material of rubber is bonded by vulcanisation to the rope.

In use, the wire saw is formed into a closed loop and rotated and advanced into a substrate being cut.

SUMMARY OF THE INVENTION

According to the invention, there is provided a wire saw comprising a rope having a layer of elastomeric material surrounding the rope and bonded to it, a plurality of spaced abrasive sleeves secured to the rope through the elastomeric layer, each abrasive sleeve presenting a cutting surface proud of the layer, and a single spiral made of elastomeric material surrounding the layer and presenting an elongate surface between successive sleeves.

Further according to the invention, the cutting surface on each abrasive sleeve and the elongate surface on the spiral are both at substantially the same height relative to the elastomeric layer.

Further according to the invention, the spiral is a right-hand spiral in the direction of rotation of the saw, in use.

Still further according to the invention, the spiral has side surfaces and a top surface and the side surfaces together form a tapered configuration from the elastomeric layer to the top surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of a portion of an embodiment of a wire saw of the invention, :

Figure 2 is a section along the line 2-2 of Figure 1, and

Figure 3 is a section along the line 3-3 of Figure 1.

DESCRIPTION OF EMBODIMENTS

The rope of the wire saw may be any suitable metal such as steel.

The abrasive sleeves will generally comprise a mass of abrasive particles such as diamond or cubic boron nitride uniformly dispersed in a metal matrix. Suitable metal matrices are well known in the art and include alloys such as bronze and alloys of cobalt and iron. Each sleeve will present at least one circumferential cutting surface.

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The elastomeric material will generally be a rubber which may be bonded by vulcanisation to the wire rope in the manner described in EP 0 317 965.

An embodiment of the invention will now be described with reference to the accompanying drawings. Referring to these drawings, there is shown a wire saw comprising a wire rope 10 surrounded by, and encased in, a layer 12 of an elastomeric rubber material.

The wire saw has a plurality of abrasive sleeves 14 uniformly spaced along the rope. Each abrasive sleeve 14 is carried on a cylindrical mount 16 which is embedded in the layer 12. In this way bonding of the sleeves 14 to the wire rope 10 is achieved.

Each abrasive sleeve 14 comprises a mass of abrasive particles uniformly dispersed in a bonding metal matrix. Each sleeve has a cutting surface 15 with a leading circumferential edge 18 and a rear circumferential edge 20.

The surface 15 stands proud of the outer surface 22 of the layer 12.

The wire saw is further provided with a spiral 24 also made of an elastomeric material and generally the same elastomeric material as that of the layer 12. A single spiral is provided and it bas the following features: 1. The spiral is right-hand in the sense that it spirals clockwise in the direction 26, which is the direction of rotation of the wire saw, in use.

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- 2. The spiral has a rib-like structure with side surfaces 28 and a top surface 30. The side surfaces 28 together form a tapered configuration from the layer 12 to the top surface 30. 3. The width of the spiral rib is substantially less and typically about one tenth of the circumference of the edge 18 of the cutting surface 15. This, it has been found, leaves sufficient space for cuttings and flushing water in the rubber recesses between successive sleeves 14.

Further, a spiral rib of such a width, it has been found, does not affect adversely the stiffness of the wire saw to any significant degree. 4. The top surface 30 of the spiral stands proud of the top surface 22 of the elastomeric layer to the same extent as the surface 15 of the sleeve 14. Thus, the top surface 30 wears as the abrasive sleeves 14 wear. 5. The pitch of the spiral is four sleeve spacings long.

It has been found that the wire saw of the invention provides very effective cutting of hard material such as concrete and stone such as marble, granite and slate. These excellent results are attributable, at least in part, to the use of a single spiral. It is believed that the spiral provides extra material and stiffening to one side of the sleeve and the spiral rib is in a different position for successive sleeves. Thus, an asymmetrical arrangement is provided which leads to dynamic instability as the wire passes around pulleys and through the cut. This instability causes the wire to move rotationally when it bends around a pulley or around corners of the cut.

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The rotational movement presents a fresh part of the abrasive sleeve to the substrate being cut and this results in even wear of the abrasive sleeve around the circumference. Such is not achievable with a multi-spiral which destroys the asymmetry.

Further, the spiral stands proud of the layer 12 and its top surface 30 is flush with the circumferential edges 18, 20 of the abrasive sleeve. The spiral thus is in contact with the material being cut. The portion of the abrasive cutting surface 15 between the spiral rib will not cut freely as it is "protected" by the spiral on either side. The next sleeve is "protected" in a different position rotationally. Thus, it is believed that this "protected" . irregularity that moves from sleeve to sleeve in a spiral form causes the wire to move rotationally, resulting in even wear of the abrasive sleeves.

The spiral will be in contact with the contact face on the drive pulley and other rigging pulleys. These pulleys are never perfectly aligned in practice so it is believed that these pulleys impart a rotational movement to the wire as the spiral rib section climbs up the side of a pulley "V" due to the greater contact friction at the rib together with its spiral form.

It is also believed that the spiral could act as an auger to pump out cuttings and thus prevent them being re-ground.

Claims (14)

i CLAIMS

1. A wire saw comprising a rope having a layer of elastomeric material surrounding the rope and bonded to it, a plurality of spaced abrasive sleeves secured to the rope through the elastomeric layer, each abrasive sleeve presenting a cutting surface proud of the layer, and a single spiral made of elastomeric material surrounding the layer and presenting an elongate surface between successive sleeves.

2. A wire saw according to claim 1 wherein the cutting surface on each abrasive sleeve and the elongate surface on the spiral are at substantially the same height relative to the elastomeric layer.

3. A wire saw according to claim 1 or claim 2 wherein the spiral is a right- hand spiral in the direction of rotation of the saw, in use.

4. A wire saw according to any one of the preceding claims wherein the spiral : has side surfaces and a top surface and the side surfaces together form a tapered configuration from the elastomeric layer to the top surface.

5. A wire saw according to any one of the preceding claims wherein the width of the spiral is substantially less than the width of the cutting surface of the abrasive sleeves.

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6. A wire saw according to claim 5 wherein the width of the spiral is about one tenth the circumference of the cutting surface of the abrasive sleeves.

7. A wire saw according to any one of the preceding claims wherein the pitch of the spiral is four sleeve spacings long.

8. A wire saw according to any one of the preceding claims Wherein the rope is made of a metal.

9. A wire saw according to claim 8 wherein the metal is steel.

10. A wire saw according to any one of the preceding claims wherein each “abrasive sleeve comprises a mass of abrasive particles uniformly dispersed in a metal matrix.

11. A wire saw according to claim 10 wherein the abrasive particles are diamond or cubic boron nitride particles.

12. A wire saw according to claim 10 or claim 11 wherein the metal matrix is bronze or an alloy of cobalt and iron.

\ A wire saw according to any one of the preceding claims wherein the elastomeric material of the layer is rubber.

14. A wire saw according to any one of the preceding claims wherein the elastomeric material of the spiral is rubber.

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A wire saw substantially as herein described with reference to any one of Figures 1 to 3 of the accompanying drawings.

DATED THIS 4TH DAY OF JUNE 1998 i re SPOOR AND FISHER APPLICANTS PATENT ATTORNEYS

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