Process for cutting stone blocks in stone quarries, and machine using the method

Abstract

 According to the invention:

• a diamond wire cutting machine (M) is provided, with a structure essentially in the form of a gantry, astride a block (B) to be cut;
• the said cutting machine (M) is freely movable under its own power and advances in a step-by-step sequence along the said block (B);
• at each step, and with the machine (M) stationary, a diamond cutting wire wound in a closed loop around a plurality of pulleys supported by the gantry structure of the machine (M) is made to run in a essentially vertical plane, engaging the block (B) from above with its lower run, and makes a through cut in the block (B), forming a corresponding "slice" (S) from it;
• subsequently, in order to cut each "slice" (S), the cutting machine (M) is positioned astride the "slice" and is made to operate according to the same cutting sequence as that described above, to cut the "slice" (S) into a plurality of essentially parallelepipedal pieces.

Description

[0001] The present invention relates to a process for cutting blocks in stone quarries and the like, and to the machine for the application of this process.

[0002] In stone quarries and the like, large blocks are obtained directly from the rock deposit by means of explosive and/or special machines, which make what is known as a "primary cut" of the block, so that it can be removed from the quarry face.

[0003] The block which has been obtained can then be subjected, in the quarry and by means of suitable machines, to further cutting operations, called the "secondary cut", to divide it into blocks which are smaller but not yet suitable for transporting out of the quarry.

[0004] However, these blocks must be cut again in the quarry into a plurality of parallelepipedal pieces or the like, of relatively small size, so that they can be prepared for transporting out of the quarry.

[0005] The blocks of stone are cut into parallelepipedal pieces by means of known cutting machines, comprising a carriage structure in which powered wheels cause the machine to advance or withdraw along fixed straight tracks during the stages of positioning and working. The carriage supports a flywheel carrier unit, in which traversing and rotation through 360° are carried out by electric motors. A diamond cutting wire, having a length of several tens of metres for example, is partially wound in a closed loop on the flywheel, and is guided by means of idle pulleys which are fixed with respect to the carriage and have axes parallel to that of the flywheel, while it is made to pass through suitable holes into the material to be cut, essentially in a "noose" configuration. Thus the stone is cut in a plane, for example a vertical plane, which contains the loop of diamond wire. During the working stage, while the diamond wire is made to run around the flywheel and execute the cut, the carriage withdraws along the track, to provide a constant tensioning of the wire, whose excess length is thus progressively taken up in accordance with the depth of the cut which is made.

[0006] There is also a known method of carrying out the aforesaid cutting by using in combination, for example, two cutting machines of the specified type, whose corresponding tracks are made to face two adjacent sides of the block, in two essentially orthogonal directions, in such a way that one of the two machines divides the block into "slices", along vertical planes parallel to its direction of travel, while the other cuts the "slices" of material thus formed into parallelepipedal pieces, by making through cuts along planes which are essentially vertical and orthogonal to the planes along which the block is divided into "slices".

[0007] This arrangement of cutting machines for cutting blocks of stone in a quarry is particularly cumbersome and also requires long periods of time for setting up for operation and for dismantling (arranging and removing the tracks).

[0008] Furthermore, this arrangement does not allow the cutting operations to be controlled in a flexible way, owing to the presence of predetermined structural constraints, such as the tracks for the cutters.

[0009] Moreover, the known diamond wire cutters used for cutting have the following major drawbacks:

• in order to operate, they require a travel path, consisting of fixed tracks, with a length at least equal to half the length of the diamond wire to be taken up during the cut;
• their diamond wires have a poor grip on the flywheel during the cut;
• on starting, the diamond wire exerts excessive pressure on the material to be cut;
• at least one through hole must be provided, by other means, in the material to be cut, to allow the diamond wire to be inserted;
• a preliminary operation is required to join together the two ends of the diamond wire, which must be separated again at the end of the operation;
• the configuration of the diamond wire essentially in the form of a "noose" during the cut increases the wear on it;
• the diamond wire, which during the cutting operation is essentially "noose"-shaped, is not guided, and therefore makes cuts which are imprecise and frequently faulty.

[0010] The present invention arises from the consideration of these shortcomings and is intended to remedy them.

[0011] The main object of the present invention is therefore to provide a process for cutting blocks in stone quarries and the like, by which the overall dimensions of the cutting machines in the quarry can be limited, the idle time of the machines due to setting up and dismantling is eliminated, and the cutting operations can be controlled in a flexible way, without structural constraints due to any arrangement of the fixed installations of the cutting machines.

[0012] The object of the invention is also to provide a machine for cutting blocks in stone quarries and the like, for the application of the aforesaid process, which does not require a predetermined travel path, can provide a correct and constant pressure of the diamond wire on the material to be cut, does not require any preliminary preparatory work either on the stone to be cut or on the diamond cutting wire, and which reduces the wear on the wire and provides correct tension.

[0013] A further object is to provide a cutting machine as specified, which can be used to make a better quality of cut.

[0014] With these objects in view, the present invention provides a process for cutting blocks in stone quarries and the like, whose principal characteristic forms the subject of Claim 1.

[0015] The invention also provides a machine for cutting blocks in stone quarries and the like, for the application of the aforesaid process, the essential characteristic of this machine being the subject of Claim 5.

[0016] Further advantageous characteristics will be made clear in the dependent claims.

[0017] The aforesaid claims are considered to be incorporated in full herein.

[0018] The present invention will be made clearer by the following detailed description which refers to the attached drawings, provided solely by way of example and without restrictive intent, in which:

• Fig: 1 is a schematic perspective view illustrating an arrangement of known means (drilling and diamond wire cutting machines) for the extraction of blocks of stone in a quarry and for the subsequent cutting into a plurality of parallelepipedal pieces, as explained in the introductory part of the present description;
• Fig. 2 is a view which is essentially similar to that of Fig. 1, but which illustrates, in addition to machines for the primary and secondary cutting of blocks of stone (according to the object of patent application No. TO99A 000820 of 24,09,99 in the name of the present applicant), the process for cutting blocks in stone quarries and the like and the corresponding machine for the application of the process, to which the present invention relates;
• Figures 3 and 4 show in greater detail, in a front and side elevation respectively, the machine according to the invention for the application of the aforesaid process.

[0019] With reference initially to Fig. 2 of the drawings, the letter B indicates a block of stone cut directly from the rock deposit by a diamond wire cutting machine, according to the subject of the aforesaid patent application No. TO99A 000820 of 24.09.99 in the name of the present applicant, to which reference should be made for further description.

[0020] As shown in the said Fig. 2, the block B is obtained from the deposit by means of what is known as the "primary cut", but could also be produced by the dividing of a larger block by "secondary cut" operations, again carried out by the same cutting machine.

[0021] For cutting into smaller pieces suitable for transporting out of the quarry, the said block B of stone is first cut into "slices" S, by through cuts executed along essentially vertical flat planes parallel to each other and orientated in a specified direction, after which each of the "slices" S of stone produced in this way is divided into a plurality of parallelepipedal pieces by other through cuts, executed along other planes which are essentially vertical and essentially orthogonal to the said first vertical planes.

[0022] For this purpose, according to the invention, use is made of a diamond wire cutting machine M, having essentially a gantry structure with two uprights and a connecting cross-piece, positioned astride the block of stone B to be cut. The said cutting machine is movable freely under its own power, by means of a powered carriage at the base of each upright, and advances in a step-by-step sequence along the said block B, in steps whose length is essentially equal to the width of each "slice" S to be cut from the block. At each step and with the machine M stationary, a diamond cutting wire wound in a closed loop around a plurality of pulleys supported by the gantry structure of the machine M is made to run in an essentially vertical plane which is essentially parallel to the median vertical plane intersecting the uprights and cross-piece of the gantry, engaging the block B from above with its lower run, which is kept under tension by the additional assistance of a pair of tensioning pulleys, one for each upright, which return the said lower run of the cutting wire at a level (an essentially horizontal plane) lying below the lower base of the said block B, which is supported for example by an embankment, in such a way that the said lower run of the cutting wire executes a through cut in the block B along the said vertical plane (the cutting plane), thus forming a corresponding "slice" S of stone from the block.

[0023] Subsequently, in order to cut each "slice" S of stone which has been cut from the block B in this way, a diamond wire cutting machine M is provided; this machine is freely movable under its own power and has the same structure as the cutting machine M described above, and is positioned astride the "slice". The said machine M advances in a step-by-step sequence along the said "slice", operating at each step and in the stationary state according to the same cutting sequence as that described with reference to the cutting of the block B, in such a way that the "slice" S of stone is cut into a plurality of essentially parallelepipedal pieces.

[0024] The constant and correct tensioning of the diamond cutting wire in the said cutting machine M is achieved by forming, in the cutting plane, a loop of the wire, which is run around a tensioning pulley which is positioned movably between two other pulleys which are preferably stationary. During the cut, the said tensioning pulley is made to run in a direction essentially parallel to the longitudinal direction of the cross-piece of the gantry structure of the cutting machine M, in such a way that the excess length of the cutting wire is taken up in the said loop of wire according to the depth of the cut which is made. After the cut has been made, the tensioning pulley runs back to return to the initial position, thus reducing the said loop of wire and making available the length of cutting wire required for starting a new cutting operation.

[0025] Advantageously, as shown in Fig. 2, there are two identical cutting machines M which operate in conjunction, one dividing a block of stone B into "slices" S and the other cutting each "slice" S into essentially parallelepipedal pieces.

[0026] To make it possible to cut a block of stone B into "slices" S and also to cut a "slice" S of stone into parallelepipedal pieces, the cutting machine M, having a gantry structure, comprises a telescopically extendible and retractable cross-piece and operates, during the cutting of the block B, with its cross-piece telescopically extended according to the width of the block, and, in the cutting of each "slice" formed from the block B, with its cross-piece telescopically retracted according to the width of the "slice".

[0027] With particular reference to Figures 3 and 4, a description will now be given of a diamond wire cutting machine, indicated by M, for the application of the process described above.

[0028] The said machine M comprises a gantry structure with two column uprights 9 and a connecting cross-piece 14.

[0029] The said cross-piece 14 has a structure which is telescopically extendible and retractable, as are the columns 9, to adapt the machine M to the overall dimensions of the material to be cut, particularly, in this example, a block of stone 19 resting on a supporting embankment.

[0030] At its base, each Column 9 is supported on a corresponding remotely controlled powered tracked carriage 12. The number 2 indicates the motor of each tracked carriage.

[0031] In particular, at least one powered tracked carriage 12 is provided with steering means (for example, two tracks driven independently) and is connected to the corresponding column 9 by a pivot, which allows it to rotate about the axis of the column. The two tracked carriages 12 can therefore have two operating configurations: one in which they are positioned parallel to each other, permitting the movement of the machine M in a predetermined direction, and the other in which they are positioned essentially orthogonally to each other, permitting the telescopic extension or retraction of the cross-piece 14 of the machine M.

[0032] The columns 9 are telescopically extended and retracted by hydraulic jack means (which are known and are not illustrated).

[0033] The cutting plane of the machine M is vertical and parallel to the vertical median plane intersection both the columns 9 and the cross-piece 14. A diamond cutting wire 13, wound in a closed loop around a plurality of pulleys 17, 4, 18 and 5 with axes orthogonal to the cutting plane, is made to run in the said vertical cutting plane.

[0034] In particular, a column 9 supports a fixed return pulley 17 at its top, above the cross-piece 14, while it also supports a powered pulley 4 which drives the diamond cutting wire 13 and is located below the said cross-piece 14. The said powered pulley 4 is made to rotate by a unit consisting of a motor 7 and reduction gear 8.

[0035] The other column 9 supports a fixed return pulley which is essentially at the same position as the cross-piece 14.

[0036] In the proximity of the base of each column 9 there is a corresponding tensioning pulley 18, supported at one end of a corresponding oscillating arm, extended within the gantry and pivoted at its other end with respect to the said column 9 so that it can oscillate about a fixed hinge axis which is orthogonal to the cutting plane. A hydraulic cylinder 3, connected to the column 9 so that it can oscillate about an axis orthogonal to the cutting plane, is connected by its rod to the said oscillating arm, to make the arm oscillate, according to the extension or retraction of its rod, about the hinge axis of the arm, thus enabling the height of the corresponding pulley 18 to be adjusted and also enabling the pulley to be positioned with its axis at a level below the base of the said column 9.

[0037] By means of this arrangement, during the cutting operation, the said tensioning pulleys 18 return the lower run of the cutting wire 13 at a level below the lower base of the said block 19, which is, for example, supported on an embankment, in such a way that the said lower run of the cutting wire 13 executes a through cut of the block 19 along the said vertical cutting plane.

[0038] Additionally, a tensioning pulley 5 is supported so that it can be moved along the cross-piece 14 by means of a corresponding carriage 16 which can run on longitudinal guides housed in the cross-piece. For this purpose, the shaft of the said powered pulley 5 is supported by the said carriage 16 and extends through a corresponding longitudinal aperture 15 provided in the cross-piece 14. The structure of the tensioning pulley 5 with the corresponding carriage 16 which is movable on guides with respect to the cross-piece 14 is, for example, known from the international application of the present applicant published under No. WO 98/35802. The said reversible gearmotor means 6 drive the said carriage 16 along the corresponding guides.

[0039] By means of this arrangement, a loop of the cutting wire is formed in the said cutting plane, the cutting wire being run around the said tensioning pulley 5, placed so that it is movable along the cross-piece 14 between two adjacent fixed pulleys, the lower powered pulley 4, and the upper return pulley 17 supported on the column 9 next to the said tensioning pulley. During the cut, the said tensioning pulley 5 is made to run by means of the corresponding carriage 16 along the longitudinal guides provided in the cross-piece 14, in such a way that the excess length of the cutting wire is taken up in the said loop of wire according to the depth of the cut which is made.

[0040] It should be noted that the length of the operating travel of the carriage 16 is essentially equal to half of the length of the diamond wire which is taken up in the course of cutting.

[0041] After the cut has been made, the tensioning pulley runs back to return to the initial position, reducing the said loop of wire and thus making available the length of cutting wire required for starting a new cutting operation,

[0042] The travel of the carriage 16 along the corresponding guides is controlled directly by an operator, or by automatic control means, according to the depth of the cut which is progressively made by the diamond wire 13.

[0043] The columns 9 are pivoted at their bases on tracked carriages 12, so that they oscillate about an axis 11, essentially horizontal and parallel to the cutting plane, while they are supported with respect to the carriages by means of corresponding hydraulic jacks 10 which are positioned in the form of struts between the columns and the corresponding carriages. The oscillation of the gantry structure about the axis 11 is therefore determined by adjustment of the extension of the rods of the said jacks 10. Thus it is possible to adjust the condition of verticality of the gantry, and therefore of the corresponding cutting plane, as required by the conformation of the ground on which the machine M moves.

[0044] The number 1 indicates an oil hydraulic control- unit for controlling the functions of the hydraulic members of the machine M.

Advantages of the invention:

[0045] The present invention provides a process for cutting blocks in stone quarries and the like, which can limit the overall dimensions of the cutting machines in the quarry and eliminate the idle time of the machines due to setting up and dismantling, and which also enables the cutting operations to be controlled in a flexible way, without structural constraints due to any arrangement of the fixed installations of the cutting machines.

[0046] The invention also provides a machine for cutting blocks in stone quarries and the like, for the application of the aforesaid process, which has a high degree of operating stability, does not require a predetermined travel path, can provide a correct and constant pressure (adhesion) of the diamond wire on the material to be cut (thus preventing the slipping of the wire), does not require any preliminary preparatory work either on the stone to be cut or on the diamond cutting wire, and which also reduces the wear on the wire.

[0047] A further advantage of the invention is that it provides a cutting machine as specified, which can provide a cut of better quality, by operating with a cutting wire which is not arranged in a noose but in the form of a closed loop with a cutting run which engages the material to be cut in the form of an open arc, guided by means of a plurality of pulleys positioned in the cutting plane.

Claims

1. Process for cutting blocks in stone quarries and the like, in which a block (B) of stone is initially cut into "slices" (S) by through cuts executed along first, essentially vertical planes which are essentially parallel to each other and are orientated in a specified direction, after which each of the "slices" (S) of stone produced in this way is divided into a plurality of parallelepipedal pieces by other through cuts, executed along other planes which are essentially vertical and essentially orthogonal to the said first vertical planes,
characterized in that

- use is made of a diamond wire cutting machine M, having essentially a gantry structure with two uprights and a connecting cross-piece, positioned astride the block of stone B to be cut;

- the said cutting machine is movable freely under its own power, by means of a powered carriage at the base of each upright, and advances in a step-by-step sequence along the said block (B), in steps whose length is essentially equal to the width of each "slice" (S) to be cut from the block;

- at each step and with the machine (M) stationary, a diamond cutting wire wound in a closed loop around a plurality of pulleys supported by the gantry structure of the machine (M) is made to run in an essentially vertical plane which is essentially parallel to the median vertical plane intersecting the uprights and cross-piece of the gantry, engaging the block (B) from above with its lower run, which is kept under tension by tensioning pulleys, which return the said lower run of the cutting wire at a level (an essentially horizontal plane) lying below the lower base of the said block (B), which is supported for example by an embankment, in such a way that the said lower run of the cutting wire executes a through cut in the block (B) along the said vertical plane (the cutting plane), thus forming a corresponding "slice" (S) of stone from the block,
and in that

- subsequently, in order to cut each "slice" (S) of stone which has been cut from the block (B) in this way, a diamond wire cutting machine (M) is provided; this machine is freely movable under its own power and has the same structure as the cutting machine (M) described above, and is positioned astride the "slice";

- the said machine (M) advances in a step-by-step sequence along the said "slice" (S), operating at each step and in the stationary state according to the same cutting sequence as that described with reference to the cutting of the block (B), in such a way that the "slice" (S) of stone is cut into a plurality of essentially parallelepipedal pieces.

2. Process according to Claim 1, characterized in that the constant and correct tensioning of the diamond cutting wire in the said cutting machine (M) is provided by forming in the cutting plane a loop of the wire, which is run around a tensioning pulley positioned movably between two other pulleys which are preferably stationary; during the cut, the said tensioning pulley is made to run in a direction essentially parallel to the longitudinal direction of the cross-piece of the gantry structure of the cutting machine (M), in such a way that the excess length or the cutting wire is taken up in the said loop of wire according to the depth of the cut which is made; and, after the cut has been made, the tensioning pulley is made to run back to return to the initial position, reducing the said loop of wire and thus making available the length of cutting wire required for starting a new cutting operation.

3. Process according to Claim 1, characterized in that two identical cutting machines (M) are provided and operate in conjunction, one dividing a block of stone (B) into "slices" (S) and the other cutting each "slice" (S) into essentially parallelepipedal pieces.

4. Process according to Claim 1, characterized in that the said cutting machine (M), having a gantry structure, comprises a telescopically extendible and retractable cross-piece and operates, during the cutting of the block (B), with its cross-piece telescopically extended according to the width of the block, and, in the cutting of each "slice" (S) formed from the block (B), with its cross-piece telescopically retracted according to the width of the "slice".

5. Machine for cutting blocks in stone quarries and the like, for the application of the process according to one or more of Claims 1 to 4, characterized in that it comprises:

- a gantry structure with two column uprights (9) and a connecting cross-piece (14), this structure being placed astride a block (B) or "slice" (S) of stone to be cut,

- a powered carriage (12) provided at the base of each column (9) of the said gantry structure, to support it, in such a way as to make the said machine freely movable under its own power, for movements including movement along the said block (B) or the said "slice" (S) of stone to be cut;

- a diamond cutting wire (13), wound in a closed loop on a plurality of pulleys (17, 4, 18 and 5), of which one (4) is powered, supported by the said gantry structure with their axes orthogonal to a cutting plane in which the said cutting wire (13) is made to run and which is essentially vertical and parallel to the vertical median plane intersecting both the columns (9) and the cross-piece (14) of the gantry;

- at least two of the said pulleys (18) being positioned to act as tensioning pulleys, each in the proximity of the base of a different one of the said columns (9),

   in such a way that the said machine (M) moves step-by-step along the said block (B) or the said "slice" (S) to be cut and, in a stationary position at each step, engages from above the block (B) or the "slice" (S) with the lower run of the said running cutting wire (13) which is kept under tension by the said tensioning pulleys (18), which return the said lower run of the cutting wire (13) at a level (an essentially horizontal plane) below the lower base of the said block (B) or of the said "slice" (S), in such a way that a through cut is made along the said vertical plane (cutting plane).

6. Machine according to Claim 5, characterized in that the said cross-piece (14) has a telescopically extendible and retractable structure, as have the said columns (9), to adapt the gantry structure of the machine (M) to the overall dimensions of the material to be cut (B, S),

7. Machine according to Claim 5 or 6, characterized in that at least one powered carriage (12) is provided with steering means and is connected to the corresponding column (9) by pivot means, which allow it to rotate about the axis of the column, in such a way as to enable the machine (M) to move in a predetermined direction and to cause the telescopic extension or retraction of the cross-piece (14) of the machine (M).

8. Machine according to Claim 5 or 6, characterized in that the said powered carriages (12) are tracked.

9. Machine according to any one of the preceding claims, characterized in that one column (9) of the said gantry structure supports a fixed return pulley (17) and the said powered pulley (4), one in a position above the said cross-piece (14) and the other in a position below it, and in that a tensioning pulley (5) is supported so that it is movable along the said cross-piece (14) by means of a corresponding carriage (16) which can run on longitudinal guides housed in the cross-piece under the control of reversible drive means (6), in such a way that a loop of the cutting wire is formed in the said cutting plane, the wire being run around the said tensioning pulley (5) which is positioned movably along the said cross-piece (14) between the said two adjacent pulleys (4, 17), one below and one above, and in that, following the reversible run of the said carriage (16) with the tensioning pulley (5) during the cut, the excess length of the cutting wire (13) is taken up in the said loop of wire according to the depth of the cut which is made, while, after the cut has been made, the said loop of wire is reduced in such a way that the length of wire required for starting a new cutting operation is made available.

10. Machine according to any one of the preceding claims, characterized in that there is provided, in the proximity of the base of each column (9) of the gantry structure, a corresponding tensioning pulley (18), supported at one end of a corresponding oscillating arm which extends into the gantry and is pivoted at its other end with respect to the said column (9) to oscillate about a hinge axis which is fixed to the said column and is orthogonal with respect to the cutting plane, while a hydraulic cylinder (3), connected to the column (9) in an oscillating way about an axis orthogonal to the cutting plane, is connected by its rod to the said oscillating arm, to make the arm oscillate - according to the extension or retraction of its rod - about its hinge axis, thus enabling the height of the corresponding pulley (18) to be adjusted and to position the pulley with its axis at a level below the base of the said column (9).

11. Machine according to any one of the preceding claims, characterized in that the columns (9) of the said gantry structure are pivoted at their bases on the tracked carriages (12), to oscillate about an axis (11) which is essentially horizontal and parallel to the cutting plane, while they are supported with respect to the carriages by means of corresponding hydraulic jacks (10) positioned in the form of struts between the columns and the corresponding carriages, in such a way that the oscillation of the gantry structure with respect to the axis (11) is determined by adjusting the extension of the rods of the said jacks (10), to adjust the verticality of the gantry and of the corresponding cutting plane.

Drawing