MACHINE FOR THE CUTTING OF GRANITE BLOCK OR OF STONE MATERIALS INTO SLABS

Abstract: According to the invention a machine is obtained, which is particularly suited for the cutting of blocks of granite (42), wherein the chain-guiding blade (13) with its corresponding chain (75) and a block of granite (42) which is to be cut into slabs roll in a relative motion without skidding. The place described by the centers of instantaneous rotation (41) is a horizontal line coinciding with the cutting profile (100). The relative non-skidding rolling motion is conveyed to the chain-­ guiding blade (13) in one embodiment, while in another embodiment it is conveyed to the block of granite (42) which is being cut. In order to convey the motion to the chain-guiding blade (13) or to the block of granite (42), there are mechanical driving means with a template (26) matching a counter-template (6, 81), or hydraulic devices using cylinders (19, 21) with a control device (97), comprising directional valves and proportional valves, or electro-mechanical means using electric motors with variable speed (63,64) and racks (51, 52).

Description: The invention concerns a machine for the cutting of granite blocks or stone materials into slabs. Some machines are known, exploiting different methods to cut granite into slabs. A known type of machine uses a frame consisting of a variable number of vertically arranged steel blades, which are parallel to one another and spaced from one another at a distance corresponding to the thickness of the slab to be obtained. Said blades are transversally connected with each other at their ends, so as to form a rigid structure. The frame is driven so as to have a horizontal pendular working motion and a vertical descending sliding motion during which a paste consisting of iron or cast-iron grit mixed with water and lime is introduced at the contact point between the granite and the blade, so that it exerts its abrasive action. This solution presents the inconvenience of causing considerable wear of the blades and of allowing very low feeding speeds in the range of 2 cm/h on a cutting width of approx. 3,5 m. Another known method, which allows higher feeding speeds, performs the cutting action by means of a large steel disc with a diameter of up to 3,5 m. on the periphery of which some diamond bits are attached. The disc, which is driven by a powerful motor, performs a working motion by rotating around its axis and a horizontal feeding motion in the direction of the length of the cut to be made. Although this cutting method allows good feeding speeds in the range of 20 cm/h, it presents some inconveniences. A first inconvenience arises from the costs of the disc and of the driving assembly which are remarkably high. Another inconvenience is that the maximum height of the cut that can be made corresponds to the radius of the diamond disc minus the radial dimension of the flange for the attachment of the driving assembly. Another cutting method uses a steel wire covered with an elastic diamond mixture. The wire is made to slide on a vertical plane by means of a motor and two pulleys which rotate around horizontal axes and which are parallel to each other, one pulley being connected with the motor, while the other is idle and functions as a transmission. Thus the working motion is transmitted to the diamond wire, while suitable means transmit to the pulleys a vertical downward motion, so as to impress to the diamond wire the feeding motion, too. The adjustment of the distance between the pulleys allows the adjustment of the width of the cut to be made. This method also presents some inconveniences, such as the high stress exerted by the wire on the granite, since, during the working process, it slides on the entire cutting length. Moreover, said wire does not wear out evenly on the entire periphery, but only in the area which comes into contact with the granite to be cut. In any case, the main inconvenience is represented by the side skid of the diamond wire from the vertical plane during its downward feeding motion, which causes a poor superficial quality of the cut granite slabs. Yet another machine is known, by means of which the above-mentioned inconveniences are eliminated. Said machine consists of a portal-shaped structure on which there is a chain-guiding blade, supporting a chain with diamond bits. The chain-guiding blade performs a downward vertical feeding motion, during which it also performs a series of pendular motions, while maintaining the co-planarity with the descending vertical plane. The chain with diamond bits, on the other hand, is driven so as to perform the working motion, consisting of a continuous rotation around the chain-support, which acts as a guide. However, an inconvenience presented by this type of machine arises from the fact that the line of the cut is not straight. The present invention has the purpose of eliminating all above-mentioned inconveniences. The BE-A-518164 discloses a machine for cutting stone material provided with a horizontal chain driven by two trucks moved desmodromically up and down along two vertical columns but, due to the fact that the chain is not guided along its length, the cut line may not be always straight. The main proposed purpose is to obtain a machine wherein the cutting line is straight and horizontal during the entire working phase. Another proposed purpose is to obtain a machine wherein the relative motion between the chain-guiding blade and the block to be cut is pendular. Not the least proposed purpose is to obtain a machine according to the invention costing remarkably less than the machines of the known types. All the above-listed purposes and others, which will be better explained hereafter are reached by means of a machine for the cutting of granite or stone materials in general into slabs, which, in accordance with the claims, includes a portal-shaped structure, at the top of which there is a chain, preferably with diamond bits, supported by a chain-guiding blade, around which it is stretched, following the same profile, said chain-guiding blade presenting at each end a thereaded lead nut connected with a vertical thereaded shaft, which is rigidly mounted on the post of the portal, said machine being characterized in that the chain-guiding blade with its corresponding chain and the cut surface of the granite block which is being cut roll with a relative motion without skidding, since the space described by the centers of instantaneous rotation is a line coinciding with the profile of the cut. According to an embodiment of the present invention, the relative rolling between the chain-guiding blade and the block of granite is achieved by driving the chain-guiding blade. The driving motion of the chain-guiding blade occurs by means of the vertical threaded shafts connected with the lead nuts, which are at the ends of the chain-guiding blade and which are driven vertically and alternatively upwards and downwards by means of hydraulic pistons, connected with a template which rolls on a counter-template. Another embodiment realizes the conveyance of the alternatively upwards and downwards vertical motion of the threaded shafts by means of a hydraulic pistons complete with proportional valves and directional ones. Another embodiment reaches the conveyance of the alternate upwards and downwards vertical motion of the threaded shafts by means of electric motors with variable speed and with a rack-and-pinion coupling at the ends of the threaded shafts. According to a varied embodiment of the same inventive idea, the relative rolling motion between the chain-guiding blade with its chain and the block of granite, which is being cut, is achieved by conveying the motion to the block of granite. In this case, the block of granite is loaded on an oscillating structure consisting of a mobile template rolling on a fixed counter-template, wherein the mobile template at the same time functions as a support for the block of granite which is being cut. Said mobile template and fixed counter-template are mounted on a trolley with wheels which rolls on tracks in order to make it easier to position the block of granite under the cutting blade. Advantageously, according to the invention, both the chain with the chain-guiding blade and the block of granite have a continuous relative pendular motion from right to left and from left to right, so that, instant by instant, only a few teeth of the chain are engaged with the block to be cut. Thus, by limiting to a rather short stretchthe contact area between the chain and the block, it is possible to build machines with lighter structures and requiring less installed power, the specific power conveyed to the material to be cut remaining the same. A consequence of what has been said, is the further advantage of building machines at decreased manufacturing and operation costs. Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter and from the enclosed drawings. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. The drawings show: Fig. 1: a front view of the machine according to the invention; Fig. 2: another embodiment according to the same inventive idea represented in Fig. 1; Fig. 3: another embodiment according to the same inventive idea represented in Fig. 1; Fig. 4: another embodiment according to the same inventive idea represented in Fig. 1. With reference to the mentioned figures, the machine, which is indicated as a whole with 1 in Fig. 1, consists of a portal 2, comprising the posts 4 and 5, which are joined together in their upper part by the horizontal beam 6. Within the posts 4 and 5 there are the vertical, threaded, grooved shafts 7 and 8 which are made to rotate by the geared motor 9 through the transmission shaft 10, which causes the rotation of the angular trasmission gears 11 and 12, which are respectively connected at the ends of the thereaded, grooved shafts 7 and 8. The angular transmission gear 11 consists of a bevel-gear pair (not represented in the drawing), wherein the bevel gear receiving the motion from the transmission shaft 10 engages the second bevel gear, which, in turn, is connected with the threaded grooved shaft 8 by means of a key. Thus, a fixed sliding connection is obtained between the transmission gear 11 and the threaded, grooved shaft 8, wherein the latter receives its rotating motion from the transmission gear 11 and, at the same time, it can slide vertically within the same. An analogous situation occurs for the vertical, threaded, grooved shaft 7 and its corresponding transmission gear 12. The chain-guiding blade 13, supporting chain 75, has at its ends the lead nuts 14 and 15, which are connected with the threaded shafts 7 and 8 respectively. Therefore, during their rotation, the threaded shafts 7 and 8 rigidly pull the chain-guiding blade 13 upwards or downwards according to the direction of rotation conveyed to them by the geared motor 9. Moreover, in correspondence with the lead nut 14 there is the geared motor 76, which is connected with chain 75 and which conveys to it the working motion, consisting of its rotation around the chain-guiding blade 13. The upper ends of the threaded shafts 7 and 8 present each a ball-and-socket joint 16 and 17 respectively, by means of which each is connected with a hydraulic piston. More specifically the ball-and-socket joint 16 connects the threaded shaft 7 with the piston 18 having a double shaft-protrusion, which slides vertically within the hydraulic cylinder 19, while the ball-and-socket joint 17 connects shaft 8 with piston 20, having a double shaft-protrusion, which slides vertically within the hydraulic cylinder 21. The ball-and-socket joints 16 and 17 have the task of conveying to the pistons 18 and 19, which are connected with them, only the vertical upward or downward movement of the shafts 7 and 8, but not their rotation movement. The upper protruding ends 22 and 23 of the pistons 18 and 20 respectively are connected throught the bars 24 and 25 with the ends of template 26, presenting a profile 27 having the shape of an arch of a circle and it rolls without skidding on the flat horizontal surface 28 of beam 6, which also functions as a counter-template. The operation of machine 1, represented in Fig. 1, occurs by sending oil under pressure into the cylinders 19 and 21 according to pre-established cyclic sequences, which are controlled by the pumping and controlling hydraulic power pack, which also in Fig. 1 has been sketchily represented and indicated with 95. Said pumping hydraulic power pack 95 sets under pressure the oil contained in the ducts 31 and 32 and, through the control of some suitable valves inserted in the circuit and not represented in Fig.1, it sends it, for instance, into chamber 44, through duct 34 and into chamber 45 through duct 35. The pushing action of the oil under pressure on piston 20 causes bar 25 to move downwards, while the action of piston 18 causes bar 24 to move upwards, so that template 26 rolls in the direction indicated with arrow 29. In order for this to occur, the electronic control system of the hydraulic power pack 95 must open the outlet openings 48 of chamber 46 and 47 of chamber 43, thus allowing the outpour of the oil contained therein, which flows back into the tank of the hydraulic power pack 95. When the pistons 20 and 18 have reached the end of their stroke, the electronic control device which is present in the hydraulic power pack 95 inverts the flows, so as to set under pressure the chambers 43 through duct 33 and 46 through duct 36, obviously offer shutting off the outlet openings 47 and 48 and opening the outlet openings 49 and 50. By doing this, template 26 moves in the direction opposite to the preceding one, i.e. it rolls in the direction opposite to arrow 29, performing a non-skidding rolling motion on the flat horizontal surface 28 of the counter-template 6. Since template 26 is connected through the bars 24 and 25 with the ends 22 and 23 of the pistons 18 and 20, and these in turn are connected through the ball-and-socket joints 16 and 17 with the thereaded shafts 7 and 8, for each displacement of template 26 there will be a corresponding vertical displacement of the threaded shafts 7 and 8 and, as a consequence, a rigid displacement of the chain-guiding blade 13. As has already been pointed out, the latter is in fact equipped at its ends with the lead-nuts 14 and 15 connected with the threads of the shafts 7 and 8. The chain-guiding blade 13 presents a profile 30, which is the same as the profile 27 of template 26 and corresponds to an arch of a circle having the same radius. Since template 26 performs a non-skidding rotation on the horizontal surface 28 of the counter-template 6, the geometric space formed by its centers of istantaneous rotation 40 is a horizontal straight line lying on the horizontal surface 28 of the counter-template 6, which, therefore, constitutes the fixed polar. As a consequence thereof, since profile 30 of the chain-supporting blade 13 is equal to profile 27 of template 26 and since the chain-guiding blade 13 and template 26 are rigidly joined together, and perform a rigid motion, even profile 30 of the chain-guiding blade 13 performs a non-skidding rolling motion on the granite block 42. Its centers of instantaneous rotation 41 describe, therefore, a geometric place of the points, which on the block of granite 42, which is being cut, constitutes the horizontal cutting line 100. In order for the cut of the block of granite 42 to be made, it is necessary that together with the vertical upward and downward pendular motions, also the continuous downward vertical feeding motion be conveyed to the chain-guiding blade 13 by means of the geared motor 9 and the threaded shafts 7 and 8. Moreover, chain 75 is driven by the action of the geared motor 76 to perform its working motion consisting of its rotation around the chain-guiding blade 13. Another embodiment of the same inventive idea is represented in Fig. 2, which differs from the preceding one represented in Fig. 1, because there is no template 26 connected with the pistons 18 and 20. In fact, in this embodiment the non-skidding rolling motion of profile 30 of the chain-guiding blade 13 on the block of granite 42 which is being cut, is completely driven by a hydraulic system. In fact said embodiment reaches a control device 97 which through some directional valves and some proportional valves (not represented in the drawing) conveyes the flow of the liquid under pressure from the hydraulic power pack 95 to the cylinder chambers 19 and 21 so that it causes the alternate lifting and lowering of the thereaded shafts 7 and 8. It is interesting to observe the substantial difference between the method of performance of this embodiment as compared to the method of performance of the previously described embodiment. In fact, in the previously described method it was sufficient to alternatively introduce the oil under pressure into the chambers of the cylinders 19 and 21, since it was the task of template 26 to copy the non-skidding rolling motion of its profile 27 with the matching profile 28 of its counter-template 6 and to transmit it to the chain-guiding blade 13, so that the latter could reproduce it in the block of granite 42 to be cut, in order to generate the horizontal cutting line 100. In the present embodiment, on the contrary, it is the task of the control device 97, by means of same directional valves and of some proportional valves, to adequately convey the flow of oil entering into and going out of the chambers of the cylinders 19 and 21, so as to directly cause on the chain-guiding blade 13 the non-skidding rolling motion of its profile 30 on the block of granite 42 to be cut,in order to produce the same result, i.e. a horizontal cutting line 100. Another embodiment of the same inventive idea is represented in fig. 3, wherein, in this case, too, the non-skidding rolling motion of profile 30 of the chain-supporting blade 13 on the block of granite 42 is obtained without the use of template 26. In this embodiment, in fact, the upper ends of the threaded shafts 7 and 8 consist of the racks 51 and 52, each of which is connected with the corresponding threaded shaft by means of a ball-and-socket joint 16 and 17 respectively. The lifting and lowering of the threaded shaft 7 occurs by means of the trasmission assembly 61, consisting of a pinion (not represented in the drawing) which engages rack 51 and is driven by motor 63. Similarly, the lifting and lowering of the threaded shaft 8 occurs by means of the transmission assembly 62 engaging rack 52 and driven by motor 64. The motors 63 and 64 have variable speeds and the variation of their number of revolutions is controlled by an electronic adjusting system, sketchily represented by assembly 65. In this embodiment, too, the assembly 65 must adjust the tensions conveyed to the motors 63 and 64 so as to convey - through the lifting and lowering of the racks 51 and 52 - the non-skidding rolling motion directly to the profile 30 on the block of granite 42, so as to make it possible to obtain the same result, i.e. the horizontal cutting line 100. An embodiment of the same inventive idea, differing from the just described one, realizes the conveyance of the vertical pendular motion to the block of granite 42 which is being cut, rather than to the chain-guiding blade 13, so that, in this case, it is surface 70 of the block of granite 42, which rolls without skidding on the surface of profile 30 of the chain-guiding blade 13. In this embodiment represented in Fig. 4, the block of granite 42, which is to be cut, is loaded on a structure 80 consisting of a frame 90, which supports the fixed counter-template 81 and the mobile template 26. The block of granite 42 is placed on the flat surface 83 of the mobile template 26, whose rounded profile 27 rolls without skidding on the flat surface 89 of the counter-template 81. In this case, too, profile 27 is a profile in the shape of an arch of a circle having a radius which is equal to the radius of profile 30 of the chain-guiding blade 13. The block of granite 42 being cut, undergoes a series of pendular motions in the directions indicated by arrow 86 which progressively bring its surface 70 under the cutting action of chain 75, applied on the chain-guiding blade 13. In this case the place of the centers of instantaneous rotation of the block of granite 42 is the horizontal, straight-line profile of surface 89. Since profile 30 of blade 13 is equal to profile 27 of template 26, it follows that the cutting profile 100 obtained on surface 70 of the block of granite, which matches it, is also horizontal and in a straight line. In order to make the machine loading and unloading operations easier, the assembly 80, which has the task of supporting and rocking the block of granite 42, can conveniently be mounted on the wheels 92, sliding on the tracks 91. On the basis of what has been described, it can be understood that with the machine according to the invention all the proposed goals have been reached. First of all, the main purpose, i.e. to obtain on the block of granite 42 a straight and horizontal cut 100, has been reached. The purpose of obtaining a machine, wherein the relative pendular motion between the chain-guiding blade 13 and the block of granite 42 has also been reached, thus allowing the construction of less costly machines. In fact, since by exploiting the pendular motion of the blade or of the block of granite, which limits to a rather short stretch the contct area between the chain and the granite to be cut, it is possible to build machines with lighter structures and requiring less istalled power, the specific power transmitted to the material to be cut remaining the same. Moreover, the reduced installed power also entrains the advantage of a reduction of the operating costs. During the manufacturing phase the invention can acquire embodiments differing from the described ones. For instance, the machine may also consist of a plurality of blades and chains arranged parallel with each other, so as to perform several cuts on the block of granite. Variations of a constructive nature may also be applied, which will, however, not exceed the scope of the claims. It is obvious that the machine according to the invention, which has been described as particularly suited for the cutting of blocks of granite, can be even more advantageously used for the cutting of other stone materials, such as marble, stones or concrete.

Claims: A machine, for the cutting of blocks of granite (42) or of other stone material, comprising a structure in the shape of a portal (2), at the top of which there is a chain (75) preferally complete with diamond bits, which is supported by a chain-guiding blade (13), around which it is streached and wherein said chain-guiding blade (13) presents at each of its ends a threaded lead nut (14, 15) connected with a vertical threaded shaft (7, 8), rigidly mounted on the vertical post (4, 5) of the portal (2), characterized in that the chain-guiding blade (13) with its chain (75) and the surface to be cut (70) of the block of granite (42) which is being cut roll with a relative motion without skidding, since the place described by the centers of instantaneous rotation (41) is a line coinciding with the cutting profile (100). A machine according to claim 1, characterized in that the place described by the centers of instantaneous rotation (41) is a straight line. A machine according to claim 2, characterized in that the place described by the centers of instantaneous rotation (41) is a horizontal line. A machine according to claim 1, or 2, or 3, characterized in that the relative rolling motion between the block of granite (42) which is being cut, and the chain-guiding blade (13) with its corresponding chain (75) is obtained by conveying the rolling motion to the chain-guiding blade (13) through adequate driving means. A machine according to claim 1, or 2, or 3, characterized in that the relative rolling motion between the block of granite (42), which is being cut, and the chain-guiding blade (13) with its corresponding chain (75) is obtained by conveying the rolling motion to the block of granite (42) through adequate driving means. A machine according to claim 4, characterized in that the rolling motion is conveyed to the chain-guiding blade (13) by means of a kinematically rigid connection of the chain-guiding blade (13) with a template (26) which rolls without skidding on the surface (28) of a counter-template (6), wherein the kinematically rigid connection between the chain-guiding blade (13) and the template (26) is obtained by means of two thereaded shafts (7, 8), which are connected with the lead nuts (14, 15) at the ends of the chain-guiding blade (13), suitable means being present for the driving of the chain-guiding blade (13) and of the template (26). A machine according to claim 6, characterized in that the notion of the chain-guiding blade (13) and of the template (26) is obtained by means of two hydraulic cylinders (19, 21) which connect the ends of the template (26) with the ends (22, 23) of the vertical thereaded shafts (7, 8), connected with the lead nuts (14, 15). A machine according to claim 4, characterized in that the rolling motion is conveyed to the chain-guiding blade (13) by means of hydraulic cylinders (19, 21) which drive the threaded shafts (7, 8) performing alternate movements, by means of a control device (97) having directional valves and proportional valves. A machine according to claim 4, characterized in that the rolling motion is conveyed to the chain-guiding blade (13) by means of electric motors (63, 64) with variable speed, which are connected with transmission assemblies (61, 62) complete with racks (51, 52), which move with alternate motions. A machine according to claim 5, characterized in that the rolling motion is conveyed to the block of granite (42) which is being cut, by the rolling without skidding of the template (26) on which it rests, on the surface (89) of the fixed counter-template (81). A machine according to claim 10, characterized in that the motion of the block of granite is driven by hydraulic pistons (84, 85) which are connected with the template (26) supporting the block of granite (42). A machine according to claim 6, or 10, characterized in that the profile (27) of the template (26) is an arch of a circle which is equal to the arch of a circle constituting the profile (30) of the chain-guiding blade (13), said chain-guiding blade (13) thus performing a horizontal straight-line cut (100). A machine according to claim 10, characterized in that the assembly (80) for the support of and the conveyance of the pendular motion to the block of granite (42) is mounted on a frame (90) which slides on tracks (91) by means of wheels (92).

Inventors: LOVATO, DIONIGIO
Applicants: LOVATO, DIONIGIO
Application year: 1989
Main classification: B28D1
IPC codes: B28D7, B28D1