Field of application

The invention relates to: a multi-wire machine for cutting blocks of natural or artificial stone, i.e. , a machine which obtains the cutting with a multitude of diamond wires, which are arranged to slide in the known way, on a block of stone for the cutting thereof into slabs, simultaneously of all or part of the block itself, and comprising a new device for controlling the reciprocal spacing of the closed loop wires, which in the return path, after cutting the block stone, can undergo lateral oscillations of the contiguous loops. Furthermore, the specific device for positioning the wire spacer means on the multi-wire cutting machine is also comprised, simplifying the assembly and maintenance operations.

Background Art

The state of the art comprises types of stone block cutting machines with multiple diamond wires where the closed loop wires run parallel inside the stone block to be cut into thin slabs, so as to make sufficiently precise planar surfaces of the slabs thus cut. Various embodiments of these machines are known wherein the individual wires are tensioned individually and are penetrated into the stone block which is cut by a precise guide upstream and downstream of the block itself being processed.

In the production technique of natural stone slabs, it is currently possible to cut slabs with a thickness of 12 and 15 millimetres which involves a centre distance between the wires provided with cutting diamond inserts of at least 20-22 millimetres.

In the art, diamond inserts with a diameter reduced to just over 5 millimetres are also made so as to allow the cutting of slabs from a block of stone with a thickness limited to about 10 millimetres, this allows to cut very thin slabs and a larger surface of stone slabs is cut for end use from the same volume of stone block. Thus, the necessary centre distance between the contiguous diamond wires is reduced to 15 millimetres, i.e., with the distance between the contiguous diamond wire inserts being reduced to 10 millimetres. The diamond wire loops also run contiguous in the path made with the wheels and rollers of the multi-wire machine on which they are mounted. Furthermore, thin slabs are more appreciated and, compatible with increased stone consumption, are cut from the block with diamond inserts on the wire with a diameter greater than 6-7 millimetres, so as to consume more energy and pulverize more material. In multi wire cutting machines the stroke speed of the wires is high, from 25 to 40 m/sec., i.e. , the wires can be subject to oscillations and vibrations while in the time of 1 second or less they travel the entire closed path of the loop on the machine, vertical and horizontal oscillations which can lead to contact between contiguous wires.

In fact, the aforementioned technical limit known in the art is related to the path of the multitude of diamond wires when they are free and are not engaged on support, tensioning or return rollers or pulleys or even immersed in the block during the cutting.

In the art a multi-wire machine with diamond insert wire loops is known from W02017056009A1 which in the loop section with the return path of the wires has tensioning devices of each wire so as to interrupt the free path section of the wire from one side of the multi-wire machine to the other: the free wire section remains about half of the complete distance of the wire in the return path.

The construction of multi-wire machines with the tensioning device of each wire on one side of the machine leaves a very long stretch in the upper return stretch of the diamond cutting wires where the wires run parallel and, obviously at the not low cutting speed, from one side of the machine to the other in just under ½ second. This operating condition, already in itself requires the control of the tension of the wires, all the more so if combined with a reduction in the pitch between contiguous diamond wires, necessary to be able to cut the slabs to 10 millimetres, which leads to make vertical and/or lateral oscillations of the wires themselves possible, with the danger of coming into contact with each other and damaging the wires themselves and the material of the stone block being cut.

Finally, to overcome this drawback, and in any case to cut stone slabs from a block with a thin thickness of 10 millimetres, a thin slab cutting machine from a stone block is known in the art where the cutting wires in the block are led to make the cut in the block even in the return path of the wire. This condition eliminates the problem of the presence of a long return stretch in the path of the diamond wires, but, contrary to expectations, generates considerable problems in conjunction with the start of the machine before beginning to perform the cutting of the wires themselves in the stone block; in fact, the two cutting sections of the same diamond wire are guided on paths with opposite directions to each other at a short distance in the cutting of the block stone, but when they are introduced into the block the wires are suspended in air and travel very close to each other at a double relative speed than that at which they are brought to perform the cutting, when immersed in the stone block. That is, the reciprocal relative speed of the contiguous wires in the cutting is 60 m/sec. and more with evident safety problems in avoiding interference between said contiguous wires and in the guide thereof at the moment of starting the cutting.

Therefore, in the state of the art, support and/or tensioning and rotation devices are known which are positioned in the return section of the diamond wires and it is also known to use said return section of the path of the diamond wires to also cut the slabs in the block.

However, it is known that multi-wire cutting machines of slabs from stone blocks have the best efficiency, reduced costs and tool life, that is, of the closed loop wire and provided with diamond inserts, if in the path thereof it has a fewer number of path deviations and contacts with pulleys or rollers which guide the position thereof or deviate the path. This condition is in contrast with the cutting of slabs with contiguous wires with opposite cutting directions, since the wires with diamond inserts have to be guided while closed in a loop during the cutting at very close heights and on slightly different cutting surfaces.

Furthermore, the construction and maintenance cost factor influences the choices of customers and users who want to cut sheets with a minimum thickness of 10 millimetres from a block of stone; and, since these multi-wire cutting machines are intended for almost continuous processing, the factor of maintenance stops is decisive in the construction of a multi-wire machine capable of cutting even sheets with a smaller thickness economically. Moreover, the current multi-wire machines for cutting stone blocks into slabs must present new cutting edges of the inserts at the entrance to the cutting in the stone block; this rotation of the cutting edge is obtained by adjusting the wire guide rollers upstream and downstream of the stone block being cut; the wire performs a rotation on itself and has new cutting edges in the block. Moreover, a more effective manner, and not concentrated near the stone block, of impressing rotation on the wire with diamond inserts is also necessary for the current multi wire machines.

Therefore, the creation of a multi-wire stone block cutting machine, which has low costs and allows to cut slabs of thin thickness from a stone block, is a technical problem not easily solved with the constructional solutions known in the art described above, therefore, the creation of a multi-wire machine which is economical to produce, to maintain and also allows the maximum exploitation of the life of the cutting wires with diamond inserts, is expected and not yet obtained in the art.

This state of the art is susceptible to considerable improvements with regard to the possibility of overcoming the drawbacks described above and creating a multi-wire machine for cutting blocks of natural or artificial stone which economically and easily cuts thin slabs.

The technical problem, therefore, underlying the present invention is to create a cutting machine with a multitude of diamond wires wherein the constitution of the parts, in particular the support, guide and tensioning of the closed loop wires, has a realization of a wire guide in the return section, while maintaining a maintenance simplicity and cost-effectiveness in the life of the machine, so as to reduce maintenance operations to short stops of the machine, but at the same time allow a precise guide of the wires in the return section, in the extension length of the closed loop diamond wire, so as not to divert the diamond wires in the return path thereof, imparting the rotation necessary to revive the cutting edge of the inserts.

A further and not last object of the present invention is to provide a contact between the diamond wires and a roller which maintains the correct distance between the wires themselves in the return path, limiting the contact of the wires and the deviation thereof.

Furthermore, a non-secondary part of the technical problem concerns the creation of the wire spacer roller and the durability thereof over time, given the abrasion effect which the diamond inserts have in the guide grooves of the spacer roller.

Finally, a further part of the technical problem described above concerns the possibility of adjusting the correct position of the rotation axis of the diamond wire spacer roller with respect to the support structure of the multi-wire cutting machine.

Summary of the Invention

This technical problem is solved, according to the present invention, by a multi-wire machine for cutting natural or artificial stone blocks, comprising: wire loops with diamond inserts of almost identical length; a motor drum for driving the cutting motion of the wires with diamond inserts; a single tensioning device of each wire loop with diamond inserts; at least one wire guide roller upstream and one downstream of the stone block being cut; characterized in that it has in the return section of the path of the wire loops with diamond inserts an assembly with spacer roller between the wires with contiguous diamond inserts, provided with grooves for inserting the contiguous wires, and mounted on the structure of the multi-wire machine; the adjustment of the rotation axis of the spacer roller performed at an angle other than a right angle, so as to impress a rotation motion thereon to the single wire with diamond inserts supported in the groove thereof; moreover, the spacer roller is provided with grooves obtained by mechanical processing over a layer of elastic-plastic material provided on the cylindrical outer surface of the spacer roller.

Moreover, in a preferred form: the outer coating of the spacer roller is obtained by hot casting said provided elastic-plastic material and subsequent mechanical processing of the grooves.

Furthermore, in an improved embodiment: around the spacer roller a perimeter frame is placed of which at least half is fed with washing water and provided with jets of water directed towards the surface of the grooves of the spacer roller.

Moreover, in a preferred embodiment: said perimeter frame is associated with an outer and lower mantle to collect the washing water falling from the spacer roller.

Furthermore, in a further embodiment: the outer and lower mantle has a shelf end protruded in the motion direction of the wires with diamond inserts, or also the outer and lower mantle has an ear-shaped end protruded towards the spacer roller from the upstream part thereof in the motion direction of the wires with diamond inserts.

Moreover, in a specific embodiment: the adjustment angle of the axis of the spacer roller is made adjustable by means of separate vertical and horizontal adjustment means on at least one of the two rotating supports of the spacer roller; the connection of the horizontal or vertical adjustment means of each rotating support allows fixing the rotation axis of the spacer roller in the desired position.

Moreover, an improved embodiment provides: the connection, between the structure of the multi-wire machine and said adjustment means, it occurs by means of a short beam on which the adjustment means are applied to perform the horizontal adjustment or the vertical adjustment.

Furthermore, in a preferred embodiment variant: the vertical or horizontal adjustment means comprise adjustment screws.

Moreover, in a further variant the adjustment means in the vertical direction or those in the horizontal direction have a double adjustment screw in at least one of the different adjustment directions, clearly on the same rotating support as the axis of the spacer roller.

Finally, in a specific embodiment: a wire spacer roller assembly with closed loop diamond inserts for a multi-wire machine for cutting stone blocks, comprising: a rotating roller on an axis transverse to the motion direction of the wires and grooves for inserting the contiguous wires; characterized in that it is mounted on the structure of the multi-wire machine existing in the upper section of the path of the wire loop; the adjustment of the rotation axis of the spacer roller is carried out at an angle other than a right angle, so as to impress a rotation motion thereon to the single wire with diamond inserts supported in the groove thereof; moreover, the spacer roller is provided with grooves obtained on a layer of elastic- plastic material provided on the cylindrical outer surface of the spacer roller.

The features and advantages of the present invention, in the realization of a multi-wire machine for cutting blocks of natural or artificial stone, provided with a wire spacer device for cutting the stone block into thin slabs, are given by way of non-limiting example, with reference to the five accompanying drawings.

Brief description of the drawings

Figure 1 is an overall schematic perspective view of a spacer roller of the diamond wires running parallel in the return stretch of the path of the diamond wire loops present in a multi-wire machine according to the invention;

Figure 2 is a schematic view from above of the spacer roller and the structure for connecting and supporting the roller to the multi-wire machine;

Figure 3 is a schematic side view of the stone block cutting machine with a multitude of diamond wire loops with inserts; in this Figure the rotating parts supporting, tensioning and guiding the diamond wire loops are visible, the stone block being processed is not shown; in the Figure the spacer roller located in the return section of the wire loops with diamond inserts is also visible;

Figure 4 is a schematic side view analogous to Figure 3 above showing only the path of the wire loops with diamond inserts and the position of the spacer roller in the return section of the loops, as evidenced by the direction of the cutting motion thereof;

Figure 5 is a schematic side view of the spacer roller and the mounting, adjustment and rotation support members on the structure of the multi-wire machine;

Figure 6 is a schematic view from above of the spacer roller as mounted on the multi-wire machine and the wires with diamond inserts guided thereon;

Figure 7 is a perspective schematic view of the spacer roller of contiguous wire loops seen from below the installation position on the machine support structure; the guided wires are visible above the spacer roller in the multi wire cutting machine;

Figure 8 is a perspective schematic view of the spacer roller of contiguous wire loops seen from above the installation position with the wires visible and present in the multi-wire cutting machine.

Detailed description of a preferred embodiment

In the Figures, the spacer roller 1 is visible, rotating around an axis A which is placed with a direction transverse to the path of the wires 2 with diamond inserts; the spacer roller has rotating supports 3 housed on a short beam 4, parallel to the direction D of the movement of the wires 2; the contact between the wire and the spacer roller 1 occurs in grooves 5 obtained by mechanical processing over a layer of elastic-plastic material 6 provided on the cylindrical outer surface of the spacer roller 1 The short beam 4 is connected with the rotating support 3 thereof by means of adjustment screws 7 in a direction parallel to the direction D of the wires with diamond inserts, i.e. , in a horizontal direction; these screws form the horizontal adjustment means of the spacer roller; while the support itself has locking screws 8 between the support and the short beam 4 which, when loosened, allow the sliding in the thrust direction of said horizontal adjustment screws; the short beam 4 is also connected near the ends 9 thereof with an adjustment screw 10, each in a direction normal to the previous ones, i.e., in a vertical direction; these screws form the vertical adjustment means of the spacer roller; these latter vertical adjustment screws 10 connect and firmly fix each respective end 9 of the short beam 4 to a bracket 11 which is fixed to the structure 12 of the multi-wire cutting machine, by means of usual fixing screws 13. Thereby, the assembly 14 forming the upper spacer roller is mounted halfway along the return stretch 15 of the cutting wires 2 provided in the multi-wire machine.

The spacer roller 1 also has an external fixed mantle 16 to wrap the roller itself below and fixed, by means of a perimeter frame 17, to said rotating supports 3. One side of said perimeter frame is advantageously hollow and has a feed with washing water, usual in multi-wire machines, by means of water connections 18. The water in the perimeter frame feeds jets, not shown, facing the surface of the grooves 5 of the roller, which wet the roller itself and by dragging also the diamond wires 2 which come into contact therewith. The excess water falls into the inner part of the mantle 16 and then onto the block being processed, while that ejected by centrifugation is collected, precisely, by an ear 20 upstream of the roller and by a shelf 19 downstream of the roller in the direction D. The shelf 19 and the ear 20 limit the spraying of centrifuged water by the motion of the wires 2 and the spacer roller 1.

Figures 3 and 4 show the other parts of the multi-wire machine which interact with said upper spacer roller assembly 14, i.e. , the wire guide rollers 21, upstream and downstream of the cut stone block not shown here, a motor drum 22, which gives the multitude of wires 2 with diamond inserts the cutting motion D, a single tensioning device 23 for each wire loop with diamond inserts and, as visible therefrom, the halfway position between the motor drum 22 and the tensioning device 23 in which the upper spacer roller assembly 14 is positioned which, as seen in the two Figures, deviates by a few tenths of a degree the path of the wires 2 with diamond inserts, i.e., without significantly influencing the winding of the wires which, as is known, tends to affect the life of wires with diamond inserts.

Figure 6 shows the angle B at which the axis A of the spacer roller 1 is adjusted with respect to the motion direction D of the wires 2 with diamond inserts. This angle is slightly greater than a right angle to allow contact between the wires 2 and the grooves 5 of the spacer roller and allow, in addition to the dragging of the roller, which thus rotates freely, also a rotation effect on the axis thereof of the single wire 2 with diamond inserts which facilitates and imprints the rotation on the wire, so as to gradually present at the entrance of the cut in the stone block below the cut a part of the cutting edge of the diamond insert which is different in the subsequent cutting steps, thus reviving the cut.

Finally, the structure 12 of the multi-wire machine is provided with multiple threaded seats 24 to accommodate the fixing screws 13 and allow for step positioning in relation to the cutting needs of the user which may differ according to the material, natural stone, which is cut. The operation of the assembly 14 with the spacer roller 1, according to the invention, takes place as described below. The wire 2 with diamond inserts wound in a loop is mounted on the rotating parts of the multi-wire machine. It is provided with a motor drum 22, a tensioning device 23 and wire guide rollers 21 with a distance between the grooves 5 equal to the distance between the wires 2 during the stone block cutting. The spacer roller has said grooves 5 at the same distance so as to keep the path of the wire loop 2 with diamond inserts aligned throughout the closed path of the loop in the multi-wire machine. The upper spacer roller assembly 14 may be mounted on existing multi-wire cutting machines in order to rotate the wire 2 with diamond inserts in the return stretch 15 of the wires. The rotation effect is more effective since the return stretch is much longer and with lower wire tension than the cutting stretch in the lower path where in use the wire guide rollers 21 impart said rotation on the wires with diamond inserts. In use it has been verified that the most advantageous condition is obtained with the angle B, of adjustment of the axis A of the spacer roller 1 , adjusted to a value of 90° +/- 1°.

The grooves 5 of the spacer roller 1 are obtained by mechanical processing from the surface of provided elastic-plastic material, realized in the most advantageous manner with hot casting in a special shape, on the cylindrical outer surface of the spacer roller 1. Such processing, although expensive, allows to obtain a certain dimensional precision of the grooves 5 and greater abrasion resistance in contact with the diamond inserts of the wire.

The spacer roller 1 is mounted on the structure 12 of the multi-wire machine, positioning the brackets 11 with the fixing screws 13 in the threaded seats 24 on said structure. As can be seen, a series of multiple threaded seats 24 allows the assembly 14 to be positioned with the spacer roller 1 in the intermediate position of the return stretch 15 of the path of the wire loop 2 most suited to the needs of the user for the material being cut. The spacer roller 1 is then adjusted so that the axis of rotation A thereof has an adjustment angle B slightly less than a right angle. The operation is made possible by the manoeuvring of the vertical adjustment screws 10 and the horizontal adjustment screws 7, so that each of the two rotating supports 3 of the spacer roller 1 are positioned on the structure 12 to align the grooves 5 of the spacer roller with the wires 2 with diamond inserts stretched on the multi-wire machine as provided with angle B. At the end of the adjustment of the axis A of the spacer roller 1 the horizontal adjustment screws 7, the vertical adjustment screws 10 and the locking screws 8 are tightened so as to hold the spacer roller in place.

Moreover, the upper spacer roller assembly 14 can be mounted in a fixed position i.e. , not provided with vertical or horizontal direction adjustments of the rotating supports of the spacer roller 1. This fixed position is prior to the manufacture of the machine at a precise adjustment angle of the axis A, both with a higher and lower value than a right angle, thus preventing inexperienced users from abnormally correcting said adjustment angle.

Furthermore, while rotating the spacer roller 1 is wetted by the washing water both on the grooves 5 and for a bit of dragging on the same wires 2 with diamond inserts so as to keep the grooves clean. Thus the water centrifuged by the rotation of the grooves 5 and the stroke of the wires 2 is collected by the outer mantle 16, the shelf 19 and the ear 20.

The advantages of the multi-wire stone block cutting machine with wire distance control device described above are summarized by the minimal influence that the spacer roller has in disturbing the normal use of the cutting wires with diamond inserts. That is, the wires 2 are not damaged by further windings on pulleys or rollers as already implemented in the prior art. Moreover, that small contact between the grooves 5 of the spacer roller and the respective wire 2 with diamond inserts, imparts, due to the particular inclination B of the axis A of the spacer roller, the rotation of the wire 2 thereon so as to force the wire to have an additional cutting edge in the diamond insert at each subsequent cut made.

In addition, the long return stretch 15 of the wire 2 with diamond inserts is divided into two parts of much shorter length so as to cause a brake on possible vibrations and oscillations vertically, but especially horizontally, avoiding that the wires 2, which run parallel, can accidentally touch, damaging the machine and the stone block being processed. Clearly, in the creation of a multi-wire machine for cutting stone blocks and wire distance control device, as described above, a person skilled in the art may apply the features described with the variants deemed appropriate, but all included in the appended claims. In fact, said adjustment means in the vertical direction i.e. , screw(s) 10 or horizontal screw(s) 7 may be present on a single end 9 of the short beam 4. Furthermore, said vertical or horizontal direction adjustment means can also be for connection and direct fixing between each rotating support of the axis A of the spacer roller 1 and the structure 12 of the multi-wire machine without the adoption of the short beam 4. Moreover, the means for adjusting the axis A can be present on only one of the two rotating supports 3 of the spacer roller 1. Thus also, although less advantageously, the adjustment means can be made with slots or a succession of holes with fixed pitch, and locking screws of the fixing members of said rotating supports 3 of the axis A of the spacer roller. Moreover, the coating of the cylindrical surface of the spacer roller can also be realized, still less advantageously, with elastic-plastic material provided with strips fixed to said cylindrical surface or also with rings of elastic-plastic material, with the grooves 5 previously formed thereon. Finally, the mantle 16, the shelf 19 and the ear 20 may not be present.