WO2014041481A1

WO2014041481A1 - Diamond wire for cutting blocks of stone material

Info

Publication number: WO2014041481A1
Application number: PCT/IB2013/058430
Authority: WO
Inventors: Carlo RUARO
Original assignee: Boart & Wire Srl
Priority date: 2012-09-14
Filing date: 2013-09-10
Publication date: 2014-03-20
Also published as: ITTV20120176A1

Abstract

A diamond wire (10) for cutting blocks of stone material and the like comprises a support cable (22) on which diamond beads (12) are present at intervals. A coaxial support element (16) is arranged between the cable and each bead (12). First fixing means (20) are provided between the support element (16) and bead (12) and second fixing means (24) are provided between the support element (16) and cable (22). The support element (16) has a helical form around the cable. This element may be advantageously formed by means of a spirally wound metallic wire. A manufacturing method is also described.

Description

DIAMOND WIRE FOR CUTTING BLOCKS OF STONE MATERIAL

The present invention relates to a diamond wire for cutting blocks of stone material and the like.

In the art, diamond wires composed of a cable (usually made of steel) having, mounted on its surface, mutually spaced sintered diamond beads or rings are known.

The manufacture of a diamond wire according to the prior art is complex and comprises the following steps.

First of all the sintered diamond beads or rings which have a hollow cylindrical shape are made. The beads may have a length for example of 3-11 mm, outer diameter for example of 4- 8 mm and inner diameter for example of 3-9 mm.

A metal bush is inserted inside each diamond bead, said bush having an outer diameter slighdy smaller than the inner diameter of the diamond bead so that there is a small amount of play between the bead and bush.

The bush has an inner diameter slighdy smaller than the outer diameter and therefore has a small wall thickness and has a length slighdy greater than the length of the bead (for example 7-14 mm). The bush is internally threaded over its whole length for the reason which will be illustrated below.

The bush is inserted inside the cavity of the bead so that the bead is centred axially with respect to the bush, and this is followed by the step where the two parts are fixed together permanendy.

One of the methods frequendy used to fix the bead to the bush is brazing or braze welding by means of which the bead is firmly welded to the bush.

A plurality of groups or bead elements formed by a bead with bush is then mounted on a metallic cable so as to form the diamond wire. The cable has a diameter slighdy smaller than the inner diameter of the bush and is formed by thin metal wires interKvined in strand form.

The cable is joined at the two ends so as to form a ring which will be wound around the pulleys of the cutting machines.

The bead with bush groups are suitably spaced (for example the interaxial distance between one bead and the next one may be between 10 and 30 mm) and the interspace between the beads is lined with a polymer material which covers completely the steel cable. For this purpose injection moulds are used where polymeric material is injected so as to cover the steel cable and penetrate deeply into the interstice formed between cable and bushes, normally with thickness of 0.05-0.5 mm so as to permanendy fix the beads to the steel cable. Owing to the fact that the inner surface of the bush is threaded and the steel cable is in turn formed by intertwined steel wires, the fluid polymeric material which penetrates internally between steel cable and bushes stably fixes the bush to the cable. In this way, during cutting with the diamond wire, the beads are prevented from rotating about the cable or sliding thereon.

The prior art, although widely established, is not without drawbacks.

In fact, as described above, the formation of a diamond wire is relatively complex and cosdy since it is required to manufacture different parts which must be then assembled together in various successive steps.

In particular, it is necessary to manufacture numerous bushes, each of which must be threaded on the inner surface, this operation having a negative effect on the production time and on the final cost of the bush.

Moreover, considering that the diamond wires are relatively long (in some cases even several tens of metres long), it is necessary to use a very large number of bushes and corresponding diamond beads so that the diamond wire obtained is relatively cosdy.

A further drawback is that the rigidity of the steel bushes may be decisive in causing possible breakage of cable and therefore of the diamond wire during cutting.

The object of the present invention is therefore that of overcoming, at least pardy, the drawbacks of the prior art.

A first task of the present invention is to provide diamond wires which require fewer machining operations and the use of parts which are less cosdy so as to reduce both the production time and the final cost.

Moreover, a second task of the present invention is to provide bushes and bead elements which are less rigid and which increase the working life of the diamond wire.

In view of these objects, according to the invention it has been thought to provide a diamond wire for cutting blocks of stone material and like, comprising a support cable on which diamond beads are present at intervals, a coaxial support element being arranged between the cable and each bead, first fixing means being provided between the support element and bead and second fixing means being provided between the support element and cable, characterized in that said support element has a helical form around the cable.

Also in view of these objects, according to the invention it has been thought to provide a method for manufacturing a diamond wire for cutting stone material and the like comprising the steps of forming diamond beads and helical support elements, inserting each bead on a helical support element and fixing them together by means of a first fixing process for obtaining a bead and support group, inserting in a spaced manner the bead and support groups on a cable and fixing the groups to the cable by means of a second fixing process.

Also according to the invention, it has been thought to provide a diamond bead element for forming cutting wires, comprising a diamond bead inside which a coaxial support element is fixed, characterized in that said support element has a helical form.

The characteristic features and advantages of the present invention will emerge more clearly from the description, provided hereinbelow, of a number of non-limiting examples of embodiment, with reference to the accompanying drawings in which:

Fig. 1 shows a schematic and longitudinally sectioned view of a diamond wire according to the present invention;

Fig. 2 shows a schematic and longitudinally sectioned view of a number of components of the diamond wire according to the present invention during a first assembly step;

Fig. 3 shows a schematic and longitudinally sectioned view of a number of components of the diamond wire according to the present invention during a second assembly step;

Fig. 4 shows a schematic and longitudinally sectioned view of a number of components of the diamond wire according to the present invention during a third assembly step; and

Figs. 5-7 shows a longitudinally sectioned view of three different embodiments of a component of the diamond wire according to the present invention.

With reference to the figures, Figure 1 shows a section of diamond wire for cutting blocks of stone according to the present invention, indicated overall by the reference number 10.

The diamond wire 10 comprises a plurality of diamond beads or rings 2 arranged at intervals on a support cable 22, advantageously of intertwined or twisted steel wires, with the arrangement of a support element 16 in between. For this purpose, each bead 12 has a through-hole 14 and is coaxially mounted and fixed onto a respective support element 16 so as to form a bead element. Advantageously, fixing is performed by means of first fixing means 20. The support element 16 is in turn fixed to the cable 22 by means of second fixing means 24, as will become clear below.

The sintered diamond beads rings or 12, known per se, have a substantially cylindrical form. Advantageously, the diamond beads 12 may have a length of between 3 and 10 mm, outer diameter of between 4 and 18 mm and inner diameter of between 3 and 9 mm. The exact dimensions will be chosen depending on the desired characteristics of the cutting wire. The diameter of the cable will also depend on the desired characteristics and the diameter chosen for the beads.

As can be clearly seen in the figures, each support element 16 is made with a helical form. In particular, said helical element may be advantageously obtained by means of a spirally wound metaUic wire 26. The number of turns used may vary, for example depending on the diameter of the wire and the length of the bead to be supported. In general, it has been found to be advantageous if the helical element 16 has a number of turns ranging between fifteen and twenty five and, preferably, in the region of twenty.

The material of the metallic wire which forms the helical element is preferably steel and, in particular, preferably galvanized steel.

The diameter of the spiral element will depend on the diameter of the cable 22 so that this element may be fitted easily onto the cable, as will be clarified below, after being inserted and fixed in the associated bead. Usually the diameter of the cable may vary between 2 and 5 mm depending on the specific use.

The wire 26 may be of various cross-section.

For example, in accordance with a possible embodiment of the present invention the metal wire 26 has a circular cross-section. Advantageously the diameter of the metallic wire 26 with a circular cross-section may range between 0.2 and 1.5 mm and, preferably, between 0.2 and 0.8 mm.

According to an alternative embodiment of the present invention the metallic wire 26 may have a cross-section which is not circular, for example oval or elliptical, rectangular or square. Figure 7 shows for example a particular embodiment of the support element 16 according to the present invention in which the spirally wound metallic wire 26 has a rectangular cross-section. Advantageously, the rectangular or square cross-section may have dimensions of between 0.1 and 5 mm, in keeping with the dimensions of the cable and the beads which are to be used. The edges of the rectangular or square cross-section may also be more or less chamfered.

If a thin diamond wire is desired, it is possible to use for example a 2 mm cable, with rriinimum radial play of 0.1 mm between cable and support element, turn thickness of 0.2 mm and radial play of 0.1 mm between the support element and inner hole of the diamond ring.

If, on the contrary, a diamond wire of greater thickness is desired, it is possible to use for example a 5 mm cable, with minimum radial play of 1 mm between cable and support element, turn thickness of 5 mm and radial play of 1 mm between support element and inner hole of the diamond ring.

In both cases, the wall thickness of the bead may be designed with the necessary dimensions for withstanding the working forces, as will be evident to the person skilled in the art.

According to a possible embodiment, the turns of the support element in operating conditions are compacted against each other (as shown in Figure 2). The term "compacted" is understood as meaning that the turns are positioned substantially adjacent to each other. Apart from the particular case of turns with a rectangular cross-section, compaction nevertheless leaves a surface discontinuity of the support element which is useful for fixing. In the case where it is wished to have a surface discontinuity (or a greater discontinuity, for example in the case of turns with a, for example, circular form), the turns may be separated from each other, also in a non-uniform manner, as will be clarified below.

In accordance with a first alternative embodiment, shown in Figure 5, the turns of a central part 161 of the element 16 are not compacted, but spaced from each other, while the turns in the vicinity of the ends 162, 163 are compacted. Advantageously, the turns in the central part 161 may be spaced from each other by an amount ranging between 0.1 and 10.0 mm.

According to a second alternative embodiment, shown in Figure 6, the turns at the two ends 162, 163 of the element 16 are spaced from each other, while the turns of the central part 161 are compacted. Advantageously, the turns in the vicinity of the ends 162, 163 may be spaced from each other by an amount ranging between 0.1 and 6.0 mm.

In both cases, the amount of the spacing may be chosen also depending on whether the support element is to occupy the entire length of the bead used.

For example, in the case of a rectangular cross-section 2 x 0.2 with a single wound turn it is possible to have a spacing of 10 mm so as to obtain a support element which is 14 mm long, such that it projects from the diamond ring which is 8 mm long. The ring will thus be welded onto a spiral band which is 2 mm wide.

Advantageously, as can be clearly seen in the various figures, during operation the ends of the helical element 16 project at the ends of the diamond bead 12.

As can be seen for example in Figure 2, the helical element 16 is inserted and centred in the associated bead 12 so that they may then be fixed together using suitable fixing means.

In accordance with a possible advantageous embodiment of the present invention, the first means 20 for fixing the diamond bead 12 to the element 16 may consist of a brazing or braze welding.

The braze welding may be performed in a manner known per se, as described above.

The diamond bead 12 is thus firmly fixed to the element 16 (as shown in Figure 3), thus forming a bead element according to the invention.

The fixing between the element 16 and bead is more effective than the fixing which can be obtained with conventional bushes which have a smooth outer surface, since the outer surface 164 of the element 16 has a helical groove defined by the turns of the metallic wire 26. Therefore, the fixing material (for example, the braze welding metal), by penetrating between the turns of the metallic wire 26 (or in any case along a superficial helical groove), results in more effective fixing between the diamond bead 12 and support element 16.

As shown in Figure 4, the cable 22 is passed inside the group formed by the support element and bead. The cable 22 is advantageously made of steel and may consist, in a manner known per se, of a plurality of steel wires wound to form the cable. The group composed of the element 16 and the diamond bead 12 is fixed to the cable 22 by means of second fixing means 24, as indicated above.

Before and afterwards, the cable 22 is joined at the two ends so as to form a ring intended to be subsequendy would around the pulleys of the cutting machines (not shown).

The groups of diamond bead 12 with element 16 are suitably spaced from each other along the cable 22 and the second fixing means, advantageously formed by means of a polymeric material, are applied. Advantageously, the polymeric material may extend along whole of the interspace between the beads which is thus lined with polymeric material which covers completely the exposed parts of the cable 22 and the support elements. As mentioned above, it is possible to use the known injection-moulding technology, using a polymeric material, performing several moulding operations in order to cover the entire length of the cable 22.

The polymeric material advantageously penetrates deeply into the spirally wound interspace formed between cable 22 and the helical support elements 16 so as to fix permanendy the diamond beads 12 to the cable 22. In fact, the injected polymeric material manages to penetrate at least superficially between the single metallic wires which form the steel cable 22 and also manages to penetrate between the various turns and/or into the superficial helical groove of the helical element 16 also in the case where the turns are adjacent to each other.

Therefore, the bond between the element 16 and the cable 22 is very strong, not only because the inner surface 165 of the helical element 16 is grooved, but also and in particular because the polymeric material manages to penetrate easily between the various turns.

The element 16 thus configured results in a greater elasticity of the system during winding onto the pulleys of the machine, said elasticity being increased by the damping effect generated by the plastic material which penetrates between the steel cable 22 and the helical element itself.

It has been found that joining together of cable 22 and helical element 16, for example performed by means of the polymeric material, is more effective where the turns of the metallic wire 26 are spaced from each other since the plastic penetrates more fully between the turns and is therefore indissolubly attached to the helical element, fixing it permanendy to the cable 22. Moreover, it has also been found that, for a stronger bond between helical element 16 and diamond bead 12, the turns are preferably adjacent to each other. In fact, it must considered that the helical element must be welded on the outside of the diamond bead and that, for a more effective weld, a broader contact surface between helical element and bead is required.

Therefore, on the one hand, for a stronger bond between cable 22 and element 16, it is preferable for all die turns to be spaced from each other, while on the other hand for better fixing together of the element and bead the turns are preferably compact.

The solution shown in Figure 6, where the turns spaced from each other are those at the two ends 162, 163 of the element 16, has therefore been found to be particularly advantageous, since the turns at the ends 162, 163 are also lined externally with the plastic material and, moreover, since they are pardy outside the diamond bead 12, the joining surface with the diamond bead 12 is not reduced significantly.

The advantages which can be obtained are thus evident. On the one hand, owing to the constructional simplicity of the helical support element 16 and therefore the constructional simplicity of the diamond wire, it is possible to obtain a diamond wire with savings in terms of time and cost.

Moreover, better bonding of the element 16 both to the diamond bead and to the steel cable is obtained, while maintaining a certain elasticity of the element 16 which ensures a longer working life of the diamond bead compared to the prior art.

It should also be noted that a helical element with a much smaller thickness may be used (in particular when made with wires having a much smaller cross-section, even in the region of 0.2 mm), so as to obtain support elements having an outer diameter smaller than in the prior art (where the need to produce an inner thread requires a certain wall thickness), for the same inner diameter (defined based on the diameter of the steel cable).

Therefore, die diameter of the beads may be reduced, with a consequent reduction in the cutting thickness of the diamond wire. Consequendy, during cutting, the amount of waste material is reduced, so that a greater number of slabs may be obtained from cutting a block of stone material.

For example, with the present invention the outer diameter of the diamond wire may be reduced to as little as 4 mm, thus resulting in a gain of 1 mm of material for each cut compared to the prior art, while leaving unchanged the diameter of the cable and therefore its strength.

Assuming for example that a block of 2 m width must be cut to produce 3 cm slabs, performing cuts with a thickness of 5 mm, the maximum number of slabs which can be obtained would be 2,000 / 35 = 57.14, i.e. 57 slabs. If instead the cutting thickness is 4 mm, as may achieved with a wire made in accordance with the present invention, the maximum number of slabs which can be obtained is 2,000 / 34 = 58.8 namely about 58 slabs and therefore one more.

With regard to the embodiments described above, the person skilled in the art may, in order to satisfy specific requirements, make modifications to and/or replace elements described with equivalent elements, without thereby departing from the scope of the accompanying claims.

For example, for each bead, each support element may also comprise several helical elements arranged alongside each other on the cable.

Claims

1. Diamond wire (10) for cutting blocks of stone material and the like, comprising a support cable (22) on which diamond beads (12) are present at intervals, a coaxial support element (16) being arranged between the cable and each bead (12), first fixing means (20) being provided between the support element (16) and bead (12) and second fixing means (24) being provided between the support element (16) and cable (22), characterized in that said support element (16) has a helical form around the cable.

2. Diamond wire according to claim 1 , characterized in that said support element is formed by a spirally wound metallic wire (26).

3. Diamond wire according to claim 1 , characterized in that the support element protrudes from the ends of the corresponding bead.

4. Diamond wire according to claim 1 , characterized in that the first fixing means consist of a braze welding (20).

5. Diamond wire according to claim 1 , characterized in that the second fixing means comprise a layer of polymeric material (24).

6. Diamond wire according to claim 5, characterized in that the layer of polymeric material also covers the space between adjacent beads.

7. Diamond wire according to claim 1 , characterized in that the helical element has turns in an intermediate segment (161) thereof differendy spaced from those in its end segments (162, 163).

8. Diamond wire according to claim 7, characterized in that the end segments (162, 163) have turns more gready spaced than those in the intermediate segment (161).

9. Diamond wire according to claim 2, characterized in that the metallic wire (26) has a circular cross-section.

10. Diamond wire according to claim 2, characterized in that the material of the metallic wire (26) is steel, preferably galvanized steel.

11. Method for manufacturing a diamond wire for cutting stone material and the like comprising the steps of forming diamond beads (12) and helical support elements (16), inserting each bead (12) on a helical support element (16) and fixing them together by means of a first fixing process for obtaining a bead and support group, inserting in a spaced manner the bead and support groups on a cable (22) and fixing the groups to the cable by means of a second fixing process.

12. Method according to claim 1 1 , wherein the helical element (16) is obtained by means of spiral winding of a metallic wire.

13. Method according to claim 1 1 , wherein the first fixing process is a braze welding process.

14. Method according to claim 11 , wherein the second fixing process consists of an injection of polymeric material.

15. Method according to claim 14, wherein the injection of polymeric material covers the spaces between adjacent beads (12) on the cable.

16. Method according to claim 12, wherein the turns of die helical element (16) are more gready spaced in the end segments of the helical element than in the intermediate segment thereof.

17. Method according to claim 12, wherein the material of the helical element (16) is steel, preferably galvanized steel.

18. Diamond bead element for forming cutting wires, comprising a diamond bead inside which a coaxial support element (16) is fixed, characterized in that said support element (16) has a helical form.

19. Bead element according to claim 18, characterized in that the coaxial support element is formed by a spirally wound metallic wire (26).

20. Bead element according to claim 18, characterized in that the support element protrudes from the ends of the corresponding bead.

21. Bead element according to claim 18, characterized in that the helical element has turns in an intermediate segment (161) thereof differendy spaced from those in its end segments (162, 163).