Blade for sawing stone material DESCRIPTION

The invention relates to a blade for sawing stone material . As is well known, the cutting of blocks of stone material such as marble, granite or the like has remained practically unchanged for decades and is performed by means of blades - usually made of steel - which are mounted in a special frame performing an oscillating movement.

It is also known that the blades in reality do not have a sharpened cutting edge nor do they have teeth; in fact the cutting effect is not obtained by means of their direct action, but as a result of friction produced by the pressure of the blade on abrasive particles which are conveyed by a viscous fluid between the bottom edge and the block to be cut. Usually, sawing is performed on a block of stone material engaged by the frame which supports a plurality of blades (usually no less than fifty in number) , the frame having tensioning members for "the individual blades and being kept moving with a to-and-fro motion of the pendulum type, for example by means of motorized operating means of the connecting rod and crank type. At the same time, as the depth of the groove or cut increases, the support frame is displaced downwards and the degree of this displacement per unit of time is referred to as the cutting speed.

The blades are normally formed with grooves on the two sides, which extend vertically and are perpendicular or inclined with respect to the cutting edge, so as to facilitate introduction of the abrasive

slurry towards the latter. However, sawing of the stone material under the conditions described is possible only at a low cutting speed ranging between about 1.5 and 7 cm/h. The cut is performed by means of abrasion of the underlying stone and the blade acts with the cutting edge alone on the abrasive slurry while performing a to-and-fro pendular movement which is produced by the motorized operating means.

Moreover, the abrasive material used does not wear away only the stone material, but also the blade itself which must therefore be replaced in order to ensure an acceptable cutting efficiency.

The effect of abrasion on the blade is moreover not uniform; in fact, the latter is subject to a greater degree of wear in the vicinity of its centre axis and to a lesser degree at its ends.

The object of the present invention is to provide a blade for sawing stone material which has structural and functional characteristics such as to improve the cutting efficiency thereof.

This object is achieved by means of a blade for sawing stone material, characterized in that -it comprises recesses on at least one of its surfaces, suitable for receiving abrasive material . In the preferred embodiment of the invention, the blade for sawing stone material comprises recesses with a substantially circular shape on the two sides.

The characteristic features and advantages of the invention will emerge from the description, given below, of an example of embodiment thereof provided by way of a non-limiting illustration with reference to the accompanying drawings .

- Figure 1 is a front view of a blade for sawing stone material in the preferred embodiment of the present invention.

- Figure 2a is a perspective view of the blade according to Figure 1.

Figure 2b is another perspective view of a variant of the blade .

- Figure 3 is a further front view of a blade for sawing stone material according to a second embodiment . - Figure 4 is a cross-sectional view of the blade in Figure 1 during a sawing operation.

- Figures 5 and 6 are further front views of sawing blades, according to further embodiments.

With reference to these figures, a sawing blade 1, shown in Figure 1, has through-holes 2a and 2b at its ends, by means of which two tie-rods 3a, 3b are pivotably mounted, said tie-rods being necessary for fixing the blade 1 to a frame (not shown in the figure) ; the blade comprises a cutting edge 4 and two sides 5, only one of which can be seen in the figure.

The blade 1 has a thickness varying between 2 and 12 mm and preferably between 4 and 5.2 mm. • ..

Advantageously, according to a preferred embodiment, the blade 1 has recesses 10 which do not pass all the way through and therefore have a blind bottom, said recesses being distributed over the entire surface of both the sides 5. Alternatively, the abovementioned blade may have recesses 10 on only one side 5; in a further variant, the recesses 10 may be present only in some portions of the sides 5.

The distances between the recesses 10 and consequently the number of recesses 10 present on the

sides 5 may be varied during the design stage depending on the characteristic parameters of the material to be cut, such as the hardness and the width of the cut to be performed. The abrasive material is composed of fine granules of a varying nature and size depending on the hardness of the material to be cut.

The use of an adhesive, where necessary, facilitates the adhesion of the fine granules of abrasive material inside the recesses 10; the adhesive usually forms an adhesive film which lines the bottom of the recess.

Alternatively, the recesses 10 may be filled with an abrasive paste which solidifies inside them; as a result of the gradual wear of the blade the recesses are uncovered and the blade assumes a "tooth" profile which allows an increase in the cutting speed.

Advantageously, additional recesses 11 are also present, being provided on the cutting edge 4 of the blade 5; the size of these additional recesses 11 may be different from that of the recesses 10 present on the sides 5 since they will be intended to allow only the start of the sawing procedure in a more efficient manner than with a flat cutting edge 4, as is normally, used.

The recesses 10 on the sides 5 and the additional recesses 11 on the cutting edge 4 are of a number and size such as to prevent excessive weakening of the blade 1 (which usually has a length, depending on the frame used, variable from 4 to 6 metres) , therefore allowing the blade to work under strength and safety conditions similar to those of blades without recesses.

In the preferred embodiment, the recesses 10 have a circular cross-section and have dimensions of between

0.3 and 1.7 mm, preferably close to 1 mm; their depth varies between 0.5 and 3 mm, preferably between 0.8 and 1.5 mm.

The additional recesses 11 preferably have a circular cross-section and have dimensions which are comparable with the dimensions of the recesses 10 formed on the sides 5. Figure 2a shows a perspective view of the blade 1 in its preferred embodiment; as can be easily noted, the recesses 10 do not pass all the way through and cover the surfaces of both sides 5, or portions thereof; alternatively, they may occupy the entire surface of one side 5.

Figure 2b, on the other hand, shows a variant of the preferred embodiment where the blade 8 also has additional recesses 11 which modify the profile of the cutting edge 4, allowing the fine granules being conveyed to be retained right from the start of the sawing operation.

Figure 3 shows a second embodiment of the present- invention in which, in order to identify identical or similar parts present in Figure 1, the same reference numbers as those already used in Figure 1 are employed," while the modified parts are indicated by reference numbers incremented by 100.

A blade 2 in Figure 3 differs from the blade 1 in Figure 1 owing to the presence of grooves 100 on one or both the sides 5; these grooves extend vertically in the direction perpendicular to the cutting edge 4 in order to help transport the fine granules towards it.

In an alternative not shown in the figures, these grooves 100 may extend also in a direction inclined with respect to the cutting edge 4.

The same comments made in connection with the preferred embodiment shown in Figure 1 are applicable to the arrangement and the characteristics of the recesses 10 and the additional recesses 11 also present in this second embodiment.

Figure 4 shows a cross-sectional view of the blade 1 in Figure 1 during cutting of a block of stone 15. As in Figure 1, the blade 1 has recesses 10 formed, in this case, on both the sides 5. Advantageously according to the invention these recesses 10 receive fine granules of abrasive material 12 fed between the cutting edge 4 of the blade 1 and the block of stone 15; in the case where the blade has already started to wear away the stone 15, the fine granules of abrasive material 12 are fed between walls 14 of a cut 13 being formed in the stone 15. Moreover they also fill the zone underneath the cutting edge 4.

In the illustration, the granules and the recesses are shown on a larger scale than that of the blade and the cut formed in the block.

The diameter of the fine granules, in the case where they have a form similar to that of spheres., may vary between 0.3 and 1.7 mm, and preferably a diameter of between 0.9 and 1.2 mm is chosen. Since, in reality, the fine granules 12 essentially have an irregular shape, the volume of each of them may be equated in the first instance to the volume of a small sphere with the diameters specified.

The operating principle of the blade according to

the invention will now be described with reference to the components shown in the figures already mentioned.

As already mentioned, the motorized means move, with a to-and-fro pendulum-like motion, a frame on which the blades 1 are tensioned by means of tie-rods 3a and 3b; these are pivotably mounted on the abovementioned blades 1 by means of through-holes 2a and 2b.

The fine granules 12 are conveyed onto the upper surface of the stone 15 and penetrate between walls 14 of the cut 13 being formed in the stone 15 and the side faces 5 of the blade, collecting on the bottom of the groove or cut 14.

The pendular motion of the blades on the fine abrasive granules 12 produces gradual wearing of the stone 15 and gradual formation of a cut 13 therein.

Advantageously, according to the invention, the presence of recesses 10 on one or both sides 5 of the blade 1, containing fine granules of abrasive material 12, results in initial abrasion of the walls 14 of the cut 13 which facilitates the flow of the fine granules 12 onto the bottom of the aforementioned cut, allowing a subsequent more rapid abrasion of the surface of the stone 15 underneath the cutting edge 4 of the blade 1. The abrasion in the vicinity of the cutting edge 4, together with the abrasion on the side walls 14 by means of the fine granules 12 present on the sides 5, makes the cutting operation less difficult.

Advantageously, according to the invention, the blade 1 results in a greater cutting speed because it improves conveying of the fine abrasive granules 12 used which are retained inside the recesses 10 and are

forced to rub against the stone 15 with a movement which is all the greater the greater the pendular movement of the blade 1, resulting in an abrasive action which is far superior to that of a conventional abrasive which is arranged on one side without recesses and normally does not follow the blade during its complete movement, being partly impeded by the roughness of the walls 14 of the cut 13.

According to the invention, conveying is advantageous both on the sides 5 and on the cutting edge 4 as wear gradually occurs; the recesses 10 open towards the cut 13, incorporating and retaining a greater quantity of fine abrasive granules 12 and increasing the abrasive performance during the pendular movement of the blade.

In the variant of the blade 8 according to Figure 2b, the blade is already provided beforehand with additional recesses 11 on the cutting edge 4.

Advantageously, according to the invention, this allows rapid initial sawing of the stone which is notoriously more difficult when the abrasive material does not have a seat inside which it can be fed and is liable to lateral displacement from the cutting edge of the blade, resulting in a reduced efficiency of the sawing operation.

Further embodiments of the blade for sawing stone material according to the invention will now be described.

Figure 5 shows a second embodiment of the blade according to the present invention in which the same reference numbers already used will be used to indicate parts identical or similar to those present in Figure 1

and reference numbers incremented by 200 will be used to identify modified parts.

In this figure, the blade 200 has recesses 210 which have an elliptical cross-section; the same comments made in connection with the blade of the preferred embodiment shown in Figure 1 are applicable to the size of the recesses and their distribution over the sides and/or on the cutting edge of the blade 200.

Figure 6 shows a third embodiment of the blade according to the present invention in which, in order to identify parts identical or similar to those present in Figure 1, the same reference numbers already used will be employed and in order to indicate modified parts reference numbers incremented by 300 will be used.

In this figure, the blade 300 has recesses 310 which have an irregular polygonal - in particular rectangular - cross-section; the same comments made in connection with the blade of the preferred embodiment shown in Figure 1 are applicable to the size of the recesses and their distribution over the sides and/or on the cutting edge of the blade 300. Alternatively, the recesses 310 may also have a regular polygonal cross-section. A further embodiment not shown in the Figures envisages the presence of recesses with different shapes on the same side, and/or on different sides, or on portions thereof, and/or on the cutting edge of the blade .